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A textbook on mechanical and electrical engineering
Paged continuously Another edition published having title: The elements of mechanical and electrical engineering v. 1. Arithmetic, Algebra, Logarithms, Geometry and Trigonometry, Elementary Mechanics, Hydromechanics, Pneumatics, Heat, with practica

A textbook on mechanical and electrical engineering
Paged continuously Another edition published having title: The elements of mechanical and electrical engineering v. 1. Arithmetic, Algebra, Logarithms, Geometry and Trigonometry, Elementary Mechanics, Hydromechanics, Pneumatics, Heat, with practica

^ 4>-'^ o s 3&

of

WORKS OF JOHN

S.

REID

PUBLISHED BY

JOHN WILEY & SONS.

A

Course

in

8vo. viil

Mechanical Drawing.

+ 186 pages,

Mechanical Drawing

168 figures.

and

Cloth, $2.00.

Elementary

Machine

Design.

By John

8. Reid, Professor of

Mechanical Draw-

Institute of Technology, and David Reid, formerly Instructor in Mechanical Drawing, Sibley College, Cornell University. 8vo.xii-f 439

ing,

Armour

pages, 301 figures.

Cloth, $3.00

A TEXT-BOOK OF

MECHANICAL

JQefcAWING

ELEME

MACHINE DESIGN. BY

JOHN

S.

Professor of Mechanical

Armour

Member

of the

Drawing and Designing, Institute;

American Society of Mechanical Engineers;

AND

DAVID REID, Formerly Instructor in Mechanical Drawing and Designing, Sibley College, Cornell University, Ithaca,

N. Y.

SECOND EDITION, REVISED AND ENLARGED. TOTAL ISSUE, SEVEN THOUSAND...,

NEW YORK:

JOHN WILEY & SONS. LONDON: CHAPMAN & HALL, LIMITED. 1908.

Engineering Library '

K

Copyright, 1900, 1908

BY

jfOhN

S.

AND

DAVID REID.

Rnbrrt Driunnuutft

anil (Sompattg

'

PREFACE TO THE SECOND EDITION.

THE

increasing use of this

book

for students of all kinds of

machine

drawing and elementary machine design, and the changes which have naturally occurred in

engineering,

since the

first

teaching

edition

was published, have made a

revision

and

the following additions both necessary and desirable.

Course II has been prepared for students

in

machine drawing

and elementary machine design who have completed the full course given in "A Course in Mechanical Drawing," by John S. Reid,

&

published by John Wiley

Sons,

New

York, or

its

equivalent.

The number selected

to

notes, bill

of

problems, their scale and

properly

of material,

size,

have been

a certain size of sheet, together with

fill

and

New

title.

illustrating bills of mateiial

and

titles,

cuts have been introduced

with dimensions for con-

struction.

A the

decidedly

minimum

directions

Instructors

from

in

new

feature has been introduced here in giving

time allowed for finishing each plate according to the

and should be

text,

when determining

their students

in

the

amount

any given term.

finish the different plates

much of

The

appreciated

work

to

by

require

time allowed to

has been carefully determined, and any

262658

PREFACE.

IV

student of fair intelligence

who

will honestly try

can finish any

of the plates in the time given.

The

Course

students

in Lettering

who have

.course in

not had

has been added for the benefit of its

equivalent in their preparatory

mechanical drawing.

Course III

a short course which has been added here as a

is

supplement to Course the

sketching,

making

II,

of

and consists of practical machine working drawings from sketches,

isometrical drawing of a lay-out of piping,

and machine design.

The

report on the "Present Practice in Drafting Methods," which will be found at the end cf the book,

new, and

will interest Instructors

and enable them

system in their drawing courses that

may

closely

to

Room is

also

adopt a

approximate

the best practice in the leading and most progressive drafting

rooms

in the

United States.

The thanks

of the authors are

extended to those

who have used

due and are most cordially book in the past and have

this

encouraged and assisted them by gracious words and timely suggestions.

JOHN

S.

D. REID. ARMOUR INSTITUTE OF TECHNOLOGY, Chicago,

111.,

September, 1908.

REID.

PREFACE.

To design

properly prepare it

students

for

advanced machine

has been found necessary to introduce a course

designed to apply the principles of mechanical drawing to the solution of practical problems in machine construction and to

arrangement and proportions of the most important machines and their details recognized by competent engineers to be the best practice of the present familiarize the student with the

time. It

is

essential to

intelligent

study and an economical

expenditure of time and labor that, before attempting to design a new machine or improve an old one, the student should post himself with

all

possible information concerning

what has already been done in the same direction. To this end the present work has been prepared.

In

it

we have attempted to show what is the best United States practice in the design and construction of various machines and

details of machines, using rules

feasible in

and formulae whenever

working out practical problems.

In addition to this will be found the latest and most

approved drafting-room methods in use in this country, without which most drawings would be practically useless. Up to the present time no text-book that

we know

of has been

VI

PREFACE

-

published in the United States that could in the best the need as explained above.

Books

of a

somewhat

tice,

same need has been

These books, modified to

have been used to some extent

fill

have been published

similar nature

in Great Britain, showing that the

there as here.

way

in this

felt

American prac-

suit

country because

they were the best to be had, but are not by any means that can be desired for our purpose in their present form.

While preparing

this course for the

all

sophomore students

in

Sibley College the authors endeavored to secure samples of

the actual machines or parts of machines as collateral in

illus-

trating the exercises given in the book, with a result that in

our drafting-rooms we have many examples of modern machine construction placed convenient to the students' hands, so that they itself

may examine and handle

the actual thing

while solving the problems in drawing and designing.

This we believe of great importance in the study of machine design and construction, because few are able to describe a

machine even with the assistance of a drawing so well as to enable the student to conceive

The

it

in his

mind

as

it

is.

actually

preparation necessary for the proper understanding

and execution of the problems contained

in this

book

is

as

follows: use of instruments, instrumental drawings applied to

drawing geometrical problems

knowledge

that

John

is

and

ink,

of the conventional lines, hatch-lining

for sections, mechanical

projection

in pencil

in

and free-hand

lettering, orthographic

the third angle, isometrical drawing

contained in

"

A

S. Reid, published

Course

in

thorough and colors

in brief all

Mechanical Drawing," by

by John Wiley

&

Sons,

New

In the preparation of the drawings for this work

York.

we

are

PREFA CE.

v ii

many of the leading engineering firms of this and States, who have kindly supplied us with drawings and

indebted to other

Our

samples of the latest and best practice of the day.

due to the Dodge Manufacturing Company, the Detroit Screw Works, the Buckeye Engine Co., the United States Metallic Packing Co., the National Tube thanks are especially

Works, the Ridgeway Dynamo

&

Engine Co., the Murray

Gun Works, Henry R. Worthington, Robt. Pool &

Sons,

the Baldwin Locomotive Works, the Schenectady Locomotive

Works, the American Pulley Co., the Hyatt Roller Bearing Co., the Macintosh and Seymour Engine Co., and many others.

Our acknowledgments

due to many of the best authorities on the different subjects treated, among which " may be mentioned Thurston's Materials of Construction,"

A.

W.

are also

Smith's "Machine

Design,"

Klein's

"Machine

" Machine " Boilers and Design," Barr's Design," Unwin's Furnaces," Peabody and Miller's "Steam Boilers," Low " and Bevis's Drawing and Designing," John H. Barr's " Steam " Thurston's Kinematics,"

Boilers,"

Reuleaux's

" Constructor," the Proceedings of the American Railway Master Mechanics' Association," etc., etc.

"

J. S.

D. R.

R,

CONTENTS.

INTRODUCTORY INSTRUCTIONS. J. S.

R.

PAGE

MECHANICAL DRAWING COMPLETE OUTFIT USE OF INSTRUMENTS SHADE-LINES AND SHADING WORKING DRAWINGS LETTERING

i

2 y

15

17 ig

FIGURING

19

STANDARD CONVENTIONS

20

CROSS-SECTIONS

26

CONSTRUCTIONS

26

ELEMENTARY MACHINE DESIGN MATERIALS OF CONSTRUCTION STRENGTH OF MATERIALS USEFUL TABLES, ETC.

29

30 36

41

CHAPTER

I.

D. R.

SCREWS, NUTS, AND BOLTS

48

CHAPTER

II.

D. R.

KEYS, COTTERS, AND GIBS

109

CHAPTER J. S.

III.

R.

RIVETS AND RIVETED JOINTS

125

CHAPTER J. S.

IV.

R.

SHAFTING AND SHAFT-COUPLINGS

157 ix

CONTENTS.

X

CHAPTER

V.

J. S. R.

PIPES AND PIPE-COUPLINGS

189

CHAPTER

VI.

D. R.

BEARINGS, SOLE-PLATES, AND

WALL BOX-FRAMES

CHAPTER

.

206

VII.

J. S. R.

BELT GEARING

238

CHAPTER J. S.

VIII.

R.

TOOTHED GEARING

262

CHAPTER

IX.

J. S. R.

VALVES, COCKS, AND OIL-CUPS

278

CHAPTER J. S.

R.

&

X.

D. R.

ENGINE DETAILS

ELEMENTARY MACHINE DRAWING (Course

305

II)

(Course III)

38i 39}

PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS AND METHODS IN

MAKING PRACTICAL WORKING DRAWINGS

419

SUGGESTED COURSES. FALL TERM. Ex.

1.

i, 3, 4,

5.6,

7, 10, 12, 13, 15,

19, 22, 24,

26, 29, 30, 32, 34, 38, 40,

-46, Si-

Ex.

2.

2, 3, 4,

5, 6,

n,

8, 10,

14, 16, 18, 20, 24, 27, 29, 31, 33, 35, 39, 41,

47, 51-

Ex.

3.

i,

3,

4,

5,

6,

8, 9, 12, 13, 17, 19, 22, 23, 25, 29, 30, 32,

34, 38, 42,

48, 5i. 4.

Ex.

2,

3,

4,

5,

6, 7,

9,

n,

14,

15, 18, 21, 24, 28, 29, 31, 33, 36, 38,

43,

49, 5i. 5.

Ex.

i, 3, 4,

5, 6, 8, 10, 12,

13, 16, 19,

22, 23,

26, 29, 30, 32, 34, 38, 44,

50, 52. 6.

Ex.

2, 3, 4, 5, 6, 7, 9,

",

*4, 17, 18, 21, 24,

27, 29, 31, 33, 37, 39, 45,

50, 52.

FALL TERM CONTINUED. 1.

Ex.

52, 54, 59, 64, 68, 73, 77, 86, 89, 90, 93.

2.

52, 55, 60, 65, 70, 74, 84, 87, 90, 92, 94.

3.

Ex. Ex.

4.

Ex.

52, 56, 62, 67, 70, 76, 84, 86, 90, 92, 94.

5.

Ex.

53, 57, 63, 68, 71, 77, 85, 87, 90, 91, 93.

6.

Ex.

53, 58, 64, 69, 72, 76, 84, 88, 90, 92, 94.

1.

Ex. 95, 97, 99, lor, 103, 106, 108, in, 113, 117, 119, 121, 124, 130,

52, 54, 61, 66, 71, 75, 85, 88, 90, 91, 93.

WINTER TERM. 136, 139, !42, 145, 147, 1492.

Ex. 96, 98, 100, 102, 104, 105, 107, 112, 114, Il8, 120, 122, 12$, 131,

.137, 140, 143, 146, 148, 149. 3.

Ex. 95, 97, 99, 101, 104, 107, no, 112,

115, 117, 121, 123, 126,

132,

138, 139, 142, 145, 147, 140. 4.

Ex. 96, 98, 100, 102, 103, 106, 108, in, 113, 116, 119, 122, 127, 133,

136, 138, 144, i%6, 148, 149. 5.

Ex. 95, 97, 99, 101, 104, 105, 108, in, 113, 116, 120, 121, 128, 134,

137, 140, 142, 145, 147, 149. 6.

Ex. 96, 98, 100, 102, 106, 107, no, 112, 115, 117, 119, 122, 129, 135,

136, 138, 143, 146, 148, 149.

DRAWING AND DESIGNING. INTRODUCTORY INSTRUCTIONS. MECHANICAL drawing

as applied to

machine drawing and

design consists of the application of descriptive geometry or

orthographic projection to the delineation of machines and parts of machines (modified tions) generally recognized It

sometimes by certain conven-

by experienced draftsmen.

comparatively a simple matter for any person of

is

average intelligence to acquire the ability of making a accurate mechanical drawing sions, but

it is

of a machine, given the

fairly

dimen-

altogether a different and more difficult prob-

lem to determine those dimensions that

will give the best

form and proportion to the different parts of the machine as will enable them to properly perform the functions for which they are intended

accordance with the strength of the

in

material of which they

A

mere copy

of a

may

be made.

drawing unaccompanied by some means

for compelling the student to study (i) the form and propor-

tions given and reasons for

some

principle

moment problem

in the

in

same or

(2) the

connected with projection

illustrations of

is

not

of

study of machine drawing and design.

drawing and design

illustrated

by

much But a

a drawing of

the object, representing the best modern practice and requiring the calculation of the proportions o{ the different parts

DRAWING AND DESIGNING.

2

from rules and formulae,

will

induce the student to think, and

tend to develop any natural ability he may have in this direcIt has been the aim of the authors in the arrangement tion. of

problems to accomplish

this

purpose

in the highest

degree

possible.

The

following notes on the complete outfit of instruments

and materials should be consulted before buying, because is

it

very essential to the best results that a good outfit be

secured.

The is

outfit for students in

mechanical and machine drawing

as follows: (i)

THE DRAWING-BOARD the

same

i6"X2i"Xj", The material should be

for

academy and freshman work

is

that

used for free-hand drawing.

soft pine

2nd constructed as shown by

as

Fig. i.

FIG.

SCRIBBLING PENCIL with rubber

(2)

i

(3)

PENCILS, one

(4)

The T-SQUARE;

head

is all

(5)

that

is

6H

tip.

and one 4!! Koh-i-noor or Faber. a plain pearwood T-square with a fixed

Length 21". "Pocket Book" Set, shown by Fig.

necessary.

INSTRUMENTS.

recommended It

i.

2,

as a first-class medium-priced set of instruments.

contains

A COMPASS,

5^" long, with fixed needle-point, pencil, pen

INTRODUCTORY INSTRUCTIONS. and

lengthening

Bow

SPRING

a

bar;

PEN, 3" long;

DRAWING-PENS, medium and

PENCIL,

Bow

a SPRING

FIG.

2

Bow

SPRING

3

3" long;

a

SPACER, 3" long;

2.

small,

HAIR-SPRING DIVIDER,

i

5" long; a nickel-plated box with leads.

FIG. 3.

(6)

A TRIANGULAR BOXWOOD

4" and (7)

2", i

i

SCALE graduated 3" and ij", i" and.*", f" and f", T

TRIANGLE "

3oX6o,

celluluid,

45

No.

(8) (9)

EMERY PENCIL POINTER.

Fig. 5.

13.

(10)

INK, black waterproof.

(i i)

INK ERASER, Faber's Typewriter.

Fig.

7.

No.

y and ^".

Fig. 4.

7"

,

IRREGULAR CURVE.

i

10" long.

"

"

as follows:

104.

DRAWING AND DESIGNING. (12)

PENCIL ERASER, "Emerald" No. 211.

(13)

SPONGE RUBBER or CUBE OF "ARTGUM."

Fig. 9. Figs. 10,

u.

FIG. 4.

FIG.

5.

FIG. 6.

(14)

small

TACKS, a small carton of

thumb

(15)

(16) (17)

i oz.

copper tacks, and

i

doz.

tacks.

ARKANSAS OIL STONE. PROTRACTOR, German " SCALE GUARD,

2

//

//

XJ XiV

silver,

/ .

about 5" diam.

" Fig. 13.

Fig. 12.

INTRODUCTORY INSTRUCTIONS,

FIG. 7

FIG. 8.

FIG. 10.

FIG. ii.

FIG. 9.

DRAWING AND DESIGNING. (18)

2 sheets of

(19)2

l<

"CREAM" DRAWING PAPER.

" IMPERIAL TRACING CLOTH.

(20)

i

CROSS-SECTION PAD.

(21)

i

SCRIBBLING PAD.

i5"X2o'

i5"X2o"

8"Xio".

FIG. 13.

FIG. 12.

(22)

i

ERASING SHIELD,

(23)

2

(24)

2

(25)

2

LETTERING PENS, "Gillott" No. 303. " " "Ball Point/' No. 506. " " " " No.

(26)

i

TWO-FOOT RULE.

nickel plated.

516.

;

IN TROD UCTOR Y INS TR UCTIONS.

INSTRUMENTS. IT

is

a

common

belief

among

students that any kind of

cheap instrument will do with which to learn mechanical drawing, and not until they have acquired the proper use of the instruments should they spend

made.

Many

buying a

in

first-

one of the greatest mistakes that can be a student has been discouraged and disgusted

This

class set.

money

is

because, try as he would, he could not using a set of instruments with which

make

it

a

good drawing, would be difficult for

even an experienced draftsman to make a creditable showing. If it is necessary to economize in this direction it is better

and easier to get along with a fewer number, and have them of the best, than it is to have an elaborate outfit of questionable quality.

The price,

instruments shown in Fig. 2 are well

and with care and attention

will give

made good

of a moderate

satisfaction for

a long time.

USE OF INSTRUMENTS. The Pencil. in pencil

first,

Designs of all kinds are usually worked out and if to be finished and kept they are inked in

and sometimes colored and shaded; but to be finished in pencil, then

center, and dimension

all

if

the drawing

is

only

the lines except construction,

lines should

be made broad and dark,

DRA WING AND DESIGNING.

8

so that the drawing will stand out clear and distinct.

be noticed that this first

a thin, even

calls

than pencil, not less

for

two kinds

made with

line

6H

(either

It will

of pencil-lines, the

a hard, fine-grained lead-

Koh-i-noor or Faber's), and

sharpened to a knife-edge in the following manner: The lead should be carefully bared of the wood with a knife for about ^", and the

wood

neatly tapered back from that point

lay the lead

upon

the emery-paper sharpener illustrated in the

;

then

and carefully rub to and fro until the pencil assumes a long taper from the wood to the point now turn it over and do the same with the other side, using toward the last a outfit,

;

slightly oscillating

motion on both sides

assumed a sharp,

thin, knife-edge

until the point has

endwise and an

elliptical

contour the other way. This point should then be polished on a piece of scrap drawing-paper until the rough burr left by the emery-paper is

removed, leaving a smooth, keen, ideal pencil-point

for draw-

ing straight lines.

With such

a point but

little

pressure

is

required in the

hands of the draftsman to draw the most desirable

line,

one

when necessary and inked in to advantage than if the line had been made with a because, when the pencil-point is blunt the incli-

that can be easily erased

much

better

blunt point, nation

is

to press hard

forms a groove

in the

draw an even inked

pencil, say

;

it

4H, and

it

line.

The second kind explained above

when drawing a line. This paper which makes it very difficult to upon

of

a pencil-line

is

the broad

line,

as

should be drawn with a somewhat softer a thicker point.

All lines not necessary to explain the drawing should be

INTRODUCTORY INSTRUCTIONS.


erased before inking or broadening the pencil-lines, so as

make

a

minimum

of erasing

and cleaning

after the

drawing

to> is;

finished.

When plane

drawing pencil-lines, the pencil should be held

passing

in a.

through the edge of the T-square perpenmaking an angle with:

dicular to the plane of the paper and

the plane of the paper equal to about

60.

Lines should always be drawn from

left to right.

A

soft

conical-pointed pencil should be used for lettering, figuring, and all free-hand work.

The Drawing-pen. is

that

shown

in

The

Fig. 14.

best form, in the writer's opinion,

The

spring on the upper blade

FIG. 15.

spreads the blades sufficiently apart to allow for thorough

The hinged

cleaning and

sharpening.

unnecessary.

The pen should be

blade

held in a

is

therefore

plane passing-

through the edge of the T-square at right angles to the plane and making an angle with the plane of the

of the paper,

paper ranging from 60 to 90.

The point,

best of drawing-pens will in time wear dull on the

and

until the student has learned

from a competent

DRA WING AND DESIGNING.

13 teacher

how

to sharpen his pens

Ihem sharpened by It is difficult to

it

would be better to have

the manufacturer.

explain the

method

of sharpening a draw-

ing-pen.

one blade has worn shorter than the other, the blades

If

rshould be brought together

by means

of the thumb-screw,

and

pen in an upright position draw the point to and on the oil-stone in a plane perpendicular to it, raising and .lowering the handle of the pen at the same time, to give the

:placing the -fro

proper curve to the point. The Arkansas oil-stones (No. 21 of " The Complete Outfit ") are best for this purpose.

The "the

pen

blades should next be opened slightly, and holding in the right

hand

in a nearly horizontal position, place

the lower blade on the stone and .slightly turning the

.handle a

little at

Jower blade a tthe .of

move

it

fro,

pen with the fingers and elevating the

the end of each stroke.

little,

quickly to and

Having ground the

turn the pen completely over and grind

upper blade in a similar manner for about the same length then clean the blades and examine the extreme time ;

points, and

if

there are

still

bright spots to be seen continue

grinding until they entirely disappear,

-the

and

finish

the

.sharpening by polishing on a piece of smooth leather.

The blades should not be too paper.

sharp, or they will cut the

The grinding should be continued only

as long as the

bright spots show on the points of the blades.

When

inking, the pen should be held in about the

position as described for holding the pencil.

men

hold the pen vertically.

The

with good results as the pen wears.

pen should only be drawn from

position

Many may be

same

drafts-

varied

Lines made with the

left to right.

INTRODUCTORY INSTRUCTIONS.

II

THE TRIANGLES. " The Complete Outfit ") are 10" and 7" long respectively, and are made of transparent The black rubber triangles sometimes used are but celluloid.

The

triangles

shown

at Fig.

4

(in

cheaper (about 10 cents) and soon become dirty when in use the rubber is brittle and more easily broken than

very

little

;

the celluloid.

Angles of 15, 75, 30, 45, 60, and 90 can readily be Lines parallel to triangles and T-square.

drawn with the

oblique lines on the drawing can be drawn with the triangles

by placing the edge representing the height so as to coincide with the given resenting

the

hypotenuse

of

line,

the

of

one of them,

then place the edge repother against the corre-

first, and by sliding the upper on the sponding edge lower when holding the lower firmly with the left hand any number of lines may be drawn parallel to the given line.

of the

The methods

and making the triangles and T-

of drawing perpendicular lines

angles with other lines within the scope of

square are so evident that further explanation

is

unnecessary.

THE T-SQUARE. The

use of the T-square

is

very simple, and

plished by holding the head firmly with the

left

is

accom-

hand against

the left-hand end of the drawing-board, leaving the right hand free to use the pen or pencil in drawing the required lines.

THE DRAWING-BOARD. If the left-hand edge of the drawing-board is straight and the T-square, then Horizontal lines parallel to the upper edge

and perpendicular to the left-hand edge may be drawn with the T-square, and lines perpendicular to these of the paper

can be made by means of the triangles, or are

sometimes

called.

set squares^ as

they

DRAWING AND DESIGNING.

12

THE TRIANGULAR This fit

"),

was

It

are

and f"

in

Fig.

arranged to suit the

drawing.

edges

illustrated

scale,

=

I

graduated as follows; I ft., i" and i" ft.,

=

i

"The Complete Out-

(in

needs of the students

triangular and made

is

=

4" and 2"

3

SCALE.

of

machine

in

boxwood.

-fa" or full size,

3" and

ij" =

I

The

six

-fa",

|"

and

ft.,

ft.

Drawings of very small objects are generally shown ene.g., if it is determined to make a drawing twice the larged an object, then where the object measures one inch the drawing would be made 2" etc. full size of

',

Larger objects or small machine parts are often size

ing

i.e., is

the same size as the object really

said to

be made

2"

=

i

ft.,

e.g.,

full

and the draw-

to the scale of full size.

Large machines and large reduced scale

is

drawn

if

details are usually

a drawing

is

to be

made

made

to a

to the scale of

then 2" measured by the standard rule would be

divided into 12 equal parts

and each part would represent

i".

THE SCALE GUARD. This instrument Outfit

").

It is

is

shown

employed

edge

No. 17

(in

"The Complete

to prevent the scale

so that the draftsman can use tee particular

in

it

from turning,

without having to look for

he needs every time he wants to lay

off

a measurement.

THE COMPASSES.

When

about to draw a

circle

or an arc of a circle, take

hold of the compass at the joint with the fingers,

thumb and two

first

guide the needle-point into the center and set the

pencil or pen leg to the required radius, then

move

and forefinger up to the small handle provided

the

thumb

at the top of

INTRODUCTORY INSTRUMENTS.

13.

the instrument, and beginning at the lowest point draw the The weight of the compass will be the only line clockwise.

down pressure required. The sharpening of the

lead for the compasses

is

a very im-

portant matter, and cannot be emphasized too much. Before commencing a drawing it pays well to take time to properly

sharpen the pencil and the lead for compasses and to keep

them always

in

good condition.

FIG. 16.

The

directions for sharpening the

compass leads are the

s?tne as has already been given for the sharpening of the straight-line pencil.

THE DIVIDERS OR SPACERS. This instrument should be held scribed for the compass.

in the

very useful

It is

To

distances on straight lines or circles. into is

any number

same manner as dein

laying off equal

divide a given line

of equal parts with the dividers, say 12,

best to divide the line into three or four parts

and then when one rately into

it

will

say 4,

been subdivided accu-

of these parts has

three equal parts,

first,

it

be a simple matter to

step off these latter divisions on the remaining three-fourths of the given line.

Care should be taken not to make holes

the paper with the spacers, as

it is

difficult to

in

ink over them

without blotting.

THE SPRING BOWS. These instruments cles

and arcs

are valuable for

of circles.

small arcs, such as

fillets,

It is

drawing the small

very important that

round corners,

etc.

,

all

cir-

the

should be care-

fully pencilled in before beginning to ink a drawing.

Many

DRAWING AND DESIGNING.

14

good drawings

are spoiled because of the bad joints between

small arcs and straight

lines.

When commencing

to ink a drawing,

small circles should be inked circles,

and the straight

first,

lines last.

all

small arcs and

then the larger arcs and

This

best, because

is

it is

FIG. 17.

much

easier to

know where

the straight line tangent to

to stop the arc line, it,

and to draw

than vice versa.

IRREGULAR CURVES. The

irregular curve

shown

in

Fig. 5

is

useful for

drawing

irregular curves through points that have already been found by

construction, such as ellipses, cycloids, epicyloids, etc., as in ths

cases of gear-teeth,

When

cam

outlines, rotary

pump

wheels, etc.

using these curves, that curve should be selected

that will coincide with the greatest line required.

number

of points on the

INTRODUCTORY INSTRUCTIONS.

15

THE PROTRACTOR. This instrument It is

shown

an angle

:

in

is

for

Fig. 12.

It

measuring and constructing angles. is used as follows when measuring

Place the lower straight edge on the straight line

which torms one

of the sides of

the angle, with the nick

exactly on the point of the angle to be measured.

number the

left;

of degrees contained in

the angle

may

Then the

be read from

clockwise.

In constructing an angle, place the nick at the point from

which

it is

desired to draw the angle, and on the outer circum-

ference of the protractor, find the figure corresponding to the

and mark a point on the paper as close as possible to the figure on the protractor; after removing the protractor, draw a line through this point

number

of degrees in the required angle,

to the nick,

which

will give the required angle.

SHADE LINES AND SHADING. Shade Lines are quite generally used on engineering workthey give a relieving appearance to the projecting parts, improve the looks of the drawing and make it easier ing drawings

to read,

;

and are quickly and

The Shading

of*

easily applied.

the curved surfaces of machine parts

is

sometimes practiced on specially finished drawings, but on working drawings most employers will not allow shading because it takes too much time, and is not essential to a quick

and correct reading of a drawing, especially shade lines is used.

The Source

of

Light

is

if

a system of

considered to be at an infinite dis-

tance from the object, therefore the Rays of Light will be represented by parallel

The Source

lines.

of Light

is

considered to be fixed, and the Point

of Sight situated in front of the object

and at an

infinite dis-

DRAWING AND DESIGNING.

i6

tance from

it,

so that the Visual

Rays are

one

parallel to

another and per. to the plane of projection.

Shade Lines divide illuminated surfaces from dark surfaces.

Dark

surfaces are not necessarily to be defined by those are darkened by the shadow cast by another which surfaces

part of the object, but

by reason

of their location in relation

to the rays of light.

the general practice to shade-line the different pro-

It is

jections of an object as

plane

e.g.,

if

each projection was

suppose a cube, Fig.

18, situated in

third angle, the point of sight in front of

FIG. 18.

it,

in the

space

same in

the

and the direction

FIG. 19.

of the rays of light coinciding with the diagonal of the cube, as

shown by

lines,

Fig. 19.

Then the edges

affi*,

b

v

c" will

be shade

because they are the edges which separate the illumi-

nated faces (the faces upon which

fall

the rays of light) from

the shaded faces, as shown by Fig. 19.

Now

the source of light being fixed, let the point of sight

INTRODUCTORY INSTRUCTIONS. remain

in

I/

the same position, and conceive the object to be re-

volved through the angle of 90 about a hor. axis so that a plan at the top of the object is shown above the elevation, and as the projected rays of light falling in the direction

diagonal of a cube

make

the use of the 45

angles of 45

triangle

we can

the

of

with the hor., then with

easily determine that the

lower and right-hand edges of the plan as well as of the

ele-

vation should be shade lines.

This practice then will be followed in this work, viz. Shade lines shall be applied to all projections of an object, :

considering the rays of light to

fall

upon each

of them, from

the same direction.

Shade

have a width equal to 3 times that of Broken lines should never be shade lines.

lines should

the other outlines.

The

outlines of surfaces of revolution should not be shade

The

lines.

shade-lined figures which follow will assist in

lustrating the above principles

;

il-

they should be studied until

understood.

WORKING DRAWINGS. Working drawings paper

in

are

sometimes made on brown

detail-

pencil, traced on tracing-paper or cloth, and then

blue printed.

The The

latter process

tracing

is

is

accomplished as follows

placed face

down on

ing-frame, and the prepared paper

the sensitized surface

in contact

is

:

the glass in the print-

placed behind

it,

with

with the back of the tracing.

In printing from a negative the sensitized surface of the

prepared paper

is

placed

negative, and the face

is

in

contact with the film side of the

exposed to the

light.

DRAWING AND DESIGNING.

*

The

blue-print system

working drawings has many-

for

drawbacks, e.g., the sectional parts of the drawing requires to

be hatch-lined, using the standard conventions already reThis takes a great deal ferred to for the different materials. of time.

The

although

this

print has usually to be is

mounted on cardboard,

not always done, and unless

it

is

the frequent handling with dirty, oily ringers soon

varnished

makes

it

unfit for use.

Changes can be made on the prints with soda-water, it is true, but they seldom look well, and when many changes or additions require to be

made

new

print.

tracing and take a

favorable to quick printing.

best to

is

it

And

make them on the

the sunlight

is

not always-

So taking everything

into con-

making working drawings directly on It is the cards and varnishing them is probably the best. system used by the Schenectady Locomotive Works and sideration the system of

engineering establishments.

many

other large

cards

are

made

of thick pasteboard

made 9" X

The drawings

paper.

12", 12"

X

18"', 18"

mounted with

X

In size the

24"; they are

Irish linen record-

are pencilled and inked on these cards-

way, and the sections are tinted with the conventional colors, which are much quicker applied than hatchin the usual

The

lines.

face of the drawing

is

protected with two coats of

white shellac varnish, while the back of the card

is

usually-

given a coat of orange shellac.

The white alcohol,

nished

it

varnish can easily be removed with a

and changes made on the drawing, and when revaris

again ready for the shop.

In the hands of an

drawing

little

is

experienced workman a working

intended to convey to him

all

the necessary

INTRODUCTORY INSTRUCTIONS. information as to shape,

material, and

size,

able him to properly construct

This means that

structions.

it

19 to

finish

en-

it without any additional inmust have a sufficient num-

ber of elevations, sections, and plans to thoroughly explain

and describe the object

in

And

every particular.

these views

The

should be completely and conveniently dimensioned.

dimensions on the drawing must of course give the sizes to which the object is to be made, without reference to the scale to which

it

may

The

be drawn.

title of

a working drawing

should be as brief as possible, and not very large plain, free-hand printed letter

is

best for this purpose.

Finished parts are usually indicated by the letter if it is all

to be finished, then below the title

" finished to write or print

number

all

a neat,

it is

'*

f,"

and

customary

over."

drawing may be placed at the upper left-hand corner, and the initials of the draftsman immediT4ie

ately below

of the

it.

Lettering.

All lettering on mechanical drawings should

be plain and legible, but the letters in a title or the figures on a drawing should never be so large as to make them appear more prominent than the drawing itself. The best form of letter for practical use is that which gives the neatest appearance with a

maximum

of legibility

quires the least amount of time and labor in

Figuring.

Great care should be taken

its

and

re-

construction.

in figuring or di-

mensioning a mechanical drawing, and especially a working drawing.

To have is

a drawing accurately, legibly, and neatly figured

considered by practical

of a

working drawing.

men

to be the

most important part

DRA WING AND DESIGNING.

20

There should be absolutely no doubt whatever about the character of a number representing a dimension on a drawing.

Many

mistakes have been made, incurring loss in time,

and money through a wrong reading of a dimension. Drawings should be so fully dimensioned that there will

labor,

be no need for the pattern-maker or machinist to measure any Indeed, means are taken to prevent him from part of them.

doing

so,

liability of the

because of the

mistakes, so drawings are often ficult to measure with a

made

common

workman

to

make

to scales which are dif-

rule,

such as 2 "and 4"

=

ft.

I

STANDARD CONVENTIONAL SECTION

LINES.

Conventional section lines are placed on drawings to distinguish the different kinds of materials used when such drawings are to be finished in pencil, or traced for blue printing, or to ;

:

used for a reproduction of any kind. Water-colors are nearly always used for finished drawings

and sometimes

The

for tracings

and pencil drawings.

color tints can be applied in

takes to hatch-line a drawing.

much

less

So that the

time than

color

it

method

should be used whenever possible.

To apply the

color tint.

Great care should be taken

in de-

termining the depth of the tint to be used; when only the section parts are to be colored the tints should be quite light because

it is

and more

much

easier to obtain an even

artistic effect.

wash and a

softer

Before applying the color the draw-

ing board should be cleared of drawing instruments, etc., so

that

it

may be

easily turned to enable the student to

keep

INTRODUCTORY INSTRUCTIONS.

and keeping the such position that the color just touches the bound-

the bounding color line always to his

brush

21

in

left,

ing line transfer the color to the drawing with long sweeps of

the brush until the surface

remaining

is

Press out

covered.

all

color

the brush with the fingers and apply the brush

in

again to the

puddles remaining on the paper. The back into itself and leave an even tint all

little

brush will draw

it

over the section.

This figure shows a collection of hatch-lined sections that is now die almost universal practice among FlG. 20.

draftsmen

in this

and other countries, and may be considered

standard.

No.

To

i.

the right

When

rocks.

is

shown a

section of a wall

used without color, as

made

of

in tracing for printing,

the rocks are simply shaded with India ink and a 175 Gillott

For a colored drawing the ground work is made To the left is the conventional of gamboge or burnt umber. For colored drawings representation of water for tracings. steel

pen.

a blended wash of Prussian blue

No.

Convention

2.

whole section

is

for

is

added.

When

Marble.

made thoroughly wet and each

colored,

stone

is

the

then

streaked with Payne's gray.

No.

Convention

3.

ground wash

umber

is

of

used.

separate dish,

The

form a

No.

little

4.

little

equal quantities and

sufficient contrast to the

ground

General Convention for Wood.

ground work should be made with a

colored,

a

crimson lake and burnt

colors for graining should be

burnt umber with a in

When

Chestnut.

gamboge with a

crimson lake added to

for

light

mixed

in a

Payne's gray and

made dark enough color.

When

wash

colored the

of burnt sienna.

22

DRAWING AND DESIGNING.

INTRODUCTORY INSTRUCTIONS. The

2$

graining should be done with a writing-pen and a dark

mixture of burnt sienna and

No.

5.

modicum

a

Convention for Black

of India ink.

A

Walnut.

mixture of

Payne's gray, burnt umber and crimson lake in equal quantiThe same mixture is used ties is used for the ground color. for graining

No.

make

color ,

6.

when made dark by adding more burnt umber.

Hard

Convention for a light

wash

of crimson lake

and burnt umber.

color

is

Convention

a light

wash

ground umbei, and

For graining use a darker mixture

parts.

7.

For the

of crimson lake, burnt

gamboge, equal No.

Pine.

for

The

ground

and the shade

lines are

Building-stone.

of Payne's gray

of

added mechanically with the drawing-pen or free-hand with the writing-pen.

No.-

8.

and neutral

Ground

Convention for Earth.

The

tint.

irregular lines to

color, India ink

be added with a writ-

ing-pen and India ink.

No.

When

9.

Section Lining for

the drawing

is

to

be

Wrought or Malleable Iron.

tinted, the color used

is

Prussian

blue.

No.

10.

These section

Cast Iron.

equidistant, not very far apart lines of the drawing.

No.

The

:

lines

i.

The

should be drawn

and narrower than the body

tint is

This section

Steel.

lines

Payne's gray.

is

used for

all

kinds of steel.

should be of the same width as those used forf-

iron

and the spaces between the double and single

be uniform.

The

son lake added to

No.

12..

color tint

make

Brass.

a

is

lines

ca'st,--.,.,

-

r

should

Prussian blue with enough crim-

warm

purple.

This section

is

generally used

for

all

kinds of composition brass, such as gun-metal, yellow metal.

<

DRA

24

AND DESIGNING.

WING.

bronze metal, Muntz metal,

dash is

etc.

The width

all

be uniform.

and spaces should wash of gamboge.

lines

a light

Nos. 1320.

The

of the full lines,

The

color tint

section lines and color tints for these

numbers

are so plainly given in the figure that further in-

struction

would seem

to

Sometimes draftsmen

be superfluous. will Crosshatch all the sectional parts

with a uniform space and ilne

mark

like that

used for cast iron and

the names of the different materials or their

initials in

some convenient place on the parts themselves. This does not look as well nor is it any more convenient to experienced

men

than the other method.

CONVENTIONAL LINES. There are four kinds:

FlG. 21. (i)

The Hidden Line.

This

line

should be

made

of short

dashes of uniform length and width, both depending some-

what on the be slightly V1

'

*p"~~~

size of

less

""

~~

the drawing.

The width should always

than the body lines of the drawing, and the ""

-

-

-

_

_____

(2

FIG. 21.

length

of the

never exceed

dash should

between the dashes should

all

".

The

spaces

be uniform, quite small, never

This line is always inked in with black ink. exceeding TV'. This line is used to indicate Motion. (2) The Line of be made shorter than those of point paths. The dashes should the hidden

line, just

a

trifle

longer than

should of course be short and uniform.

dots.

The

spaces

INTRO D UCTOR Y INS TR UCTIONS. Center Lines.

(3)

Most drawings

of

machines and parts

When of machines are symmetrical about their center lines. a drawing these lines may be drawn continuous and penciling

on drawings for reproductions the blackshould be a long narrow dash and two short ones

as fine as possible, but

inked line alternately.

When

colored inks are used the center line should

be made a continuous red line and as

make

it is

possible to

it.

(4)

are

fine as

Dimension Lines and Line of Section.

made

in

alternately.

These

lines

black with a fine long dash and one short dash

In color they should be continuous blue lines.

Colored lines should be used wherever feasible, because they are so quickly

a

much

drawn and when made

neater appearance than

lines are used.

they give the drawing

when the conventional black

Colored lines should never be broken.

.

FlG. 22.

fine

CONVENTIONAL BREAKS. drawings sometimes to indiactually longer than it is drawn, some-

Breaks are used

cate that the thing

is

in

FIG. 22.

DRAWING AND DESIGNING.

26

times to show the shape of the cross-section and the kind of material.

Those given

22 show the usual practice.

in Fig.

CROSS-SECTIONS. FlG. 23.

When

other similar object

a cross-section of a pulley, gear-wheel or is

required and the cutting-plane passes

through one of the spokes or arms, then only the rim and hub should be sectioned, as shown at xx No. I and zz No. 2, and the arm or spoke simply outlined.

may

be made as shown at

AA

gear-wheels only the number

need be drawn lines, e.g.,

;

the balance

No.

Cross-sections of the arms

In working drawings of of teeth included in one quadrant is

2.

usually

the pitch line the same

shown by conventional

as a center line, viz., a long

FIG. 23.

dash and two very short ones alternately or a red

fine

continuous

line.

The addendum same

line (d)

and the root or bottom

line (b)

the

one long dash and one short The end elecontinuous blue line.

as a dimension line, viz.,

dash alternately or a

fine

made by

vation of the gear-teeth should be

No.

projecting only

the points of the teeth, as shown Other conventions will be referred to in the text conat

2.

nected with the figures in which they are illustrated. To draw the curve of intersection that Constructions.

formed by a plane cutting an irregular surface

is

of revolution.

INTRODUCTORY INSTRUCTIONS.

2J

24 and 25 show examples of engine connectingthe curve 7 is formed by the intersection of ends where rod Figs.

FIG. 24.

the

flat

stub end with the surface of revolution of the turned

part of the rod.

FIG. 25.

Divide the

line

AB,

Figs.

of equal parts and through

center line CD.

with

CD

24 and 25, into any number

them describe

Through the

draw horizontals

arcs cutting the

intersections

of

these

to intersect the curve or

arcs

fillet

G.

DRA WING AND DESIGNING.

28

intersections on

Through the

from the divisions on

draw perpendiculars and

draw horizontals

to intersect the

these latter intersections are points in the

perpendiculars;

curve

AB

G

/.

The curve

E

can be found in a similar

way

as

shown by

the figure.

D

B

FIG. 26.

To draw

FIG. 27.

the projections of a V-threaded screw and

its

nut

of 3" diam. and |" pitch.

Begin by drawing the center line C, Fig. 26, and lay off on each side of it the radius of the screw ij". Draw A B

and 6D. off

Draw A6

the pitch

=

the bottom of the screw, and on

f", beginning at the point

A.

AB

step

INTRODUCTORY INSTRUCTIONS. On pitch

line

=

6D from

the point 6 lay

because when

",

pleted half a revolution distance

=

From

desired.

coma

the point

triangle

O

on

6D

step off as

these into any

number

number

many

pitches as

the points of the threads just found,

line

and T-square the V of the threads the bottom of the threads. b

.

.

.

A6

.

draw two semicircles with

the top and bottom of the thread

the same

half the

have risen perpendicularly

will

it

intersecting at the points b

At

=

half the pitch, viz,, f".

draw with the 30

=

a distance

the point of the thread has

.Then from the point 6" on

may be

off

29

of equal parts

of equal parts.

respectively.

and

also the pitch

Through these

radii

Divide

Pinto

divisions

draw hors. and pers. intersecting each other in the points as shown by Fig. 26, which shows an elevation partly in section and a section of a nut to of intersection

No.

fit

the screw.

draw the curves

3 of the "Sibley College

Through the points

of the helices shown, using

Set"

of Irregular Curves.

ELEMENTARY MACHINE DESIGN. "

A

a machine, according to Prof. John H. Barr, is combination of resistant bodies for modifying energy and

doing work, the members of which are so arranged that, in operation, the motion of any member involves definite, relative, constrained

motion of the others."

In order to obtain the most desirable results in designing

such a structure

composing

it

it

is

necessary to give the several bodies

such form and proportion as will enable them to

perform their functions

in

the best possible

same time present a pleasing appearance

way and

at the

to the experienced

DRAWING AND DESIGNING.

30

must not be forgotten that these should be sought with a due regard to economy

And, moreover,

eye.

desired results of material

it

and construction.

The form

of a

machine

will

probably depend largely upon

the designer's experience and his natural ability or intuition.

The

may be calculated if many cases these forces

proportion of the several parts

the opposing forces are known, but in cannot be accurately determined and the designer must rely upon the most approved practice of the past had under similar conditions.

MATERIALS USED The

IN

MACHINE CONSTRUCTION.

principal materials used in

be divided into three heads, Metals, and

machine construction may

viz.:

Cast Metals,

Wrought

Wood. CAST METALS.

Among

the cast metals the

construction are cast iron, brass,

copper-bronze

or

more important

in

malleable cast iron,

gun-metal,

machine

cast steel,

phosphor-bronze, and

aluminum.

Cast Iron. gray are

The

used

Three kinds of white

whitest iron

is

cast iron

and three of

ways

in

machine construction.

very hard and

is

used like the others of

different

in

making wrought iron. The gray irons do not melt as readily as the white, but The grayest irons are the are more fluid when melted. its class for

weakest and are used only for mixing with others cupola.

in

the

IN TROD UCTOR Y INS TR UCTIONS.

in

.

3

I

Ordinary cast iron contains from 3$ to 5$ of carbon, which the white iron is fully combined with the iron, while only

.6$ to 1.5$

shows

combined

is

in

the gray iron and 2.9$ to 3.7$

as graphite crystals.

made from

Iron castings of machine-parts are

These patterns are made

of

wood, usually

The

exactly like the castings desired.

make moulds

in

sand

poured the molten

in

patterns.

soft pine, in

form

patterns are used to

the foundry and into these moulds

is

iron.

Cast iron after solidifying in the moulds contracts while cooling about J" per foot of length.

To

allow for this con-

traction pattern-makers use a special rule called a shrink-rule for

measuring patterns;

standard

it

is

-J"

per foot longer than the

rule.

Sharp corners the metal, but possible sJiarp

in

patterns do not cast sharp and square in

come out ragged and edges should be

blunt, so that

rounded and sharp concave

corners filleted or partially filled in; the result

and better-looking

To cooling

whenever

is

a stronger

casting.

avoid irregular internal strains in iron castings

when

necessary that the section of the casting be

made

it is

as uniform as possible, so that the metal

may

contract uni-

formly throughout.

Melted gray cast iron if cooled quickly chemical combination a large amount of carbon

Chilled Castings. retains

in

which otherwise would be separated from the casting. The result is a white hard iron called chilled cast iron. To secure this quick cooling the mould into which the metal cast

is

made

of thick cast iron,

the molten metal in

much

less

is

which draws the heat from

time than does the sand mould.

DRAWING AND DESIGNING,

32

Malleable Castings are made by putting a gray-iron casting in a suitable box and covering it with powdered red hematite, which is an oxide of iron, and keeping it in a furnace at a bright-red heat for from two to thirty hours or

even longer, depending upon the

size of the casting;

such

castings are valuable for small light parts of machines, because

they are tough and strong. like

wrought

Cast Steel steel in

but

iron,

will

Malleable castings can be worked not weld.

made by melting broken

is

pieces of blister-

a closed crucible and casting into ingots.

Brass

is

much

very

used, because

it

is

easy to work,

The

usual

of zinc, with

some-

cheap, strong, and tough, and of a good cdor.

composition of brass times a

little

2 of .copper to

I

lead added.

Muntz Metal 2 of zinc.

is

It

is

a brass composition of 3 parts copper to

can be rolled or forged when hot and

used

is

the shape of bolts and nuts, sheets for sheathing vessels,

and often takes the place

its ability

is

in

wooden

of iron or steel because of

to withstand the corrosive action of water.

Copper. Pure copper with a small addition of phosphorus makes fairly good castings, but it is difficult to obtain sound castings from copper alone. Copper has a reddish-

brown color and

is

very malleable and ductile when pure.

It

can be hammered, rolled, and forged when hot or cold; joints The can be united by brazing, but welding is difficult. annealing of iron and steel

is

effected

by heating and slow

cooling, while copper can only be annealed by heating and

quick cooling.

Bronze or Gun-metal. 9 parts of copper to

I

The

of tin.

best composition

is

made

For bearings designed

of

to sus-

INTRODUCTORY INSTRUCTIONS. tain great pressure very hard

the proportion of tin

is

bronze

is

33

often used, in which

increased to 14 parts with 86 parts of

copper.

This alloy

Phosphor-bronze. to

2%

many

4$ of phosphorus to the

is

common

made by adding from bronze.

used for

It is

things in place of iron and steel, such as pump-rods,

ship-propellers, etc. tive axle.-bearings

also used quite largely for

it is

;

and shows excellent wearing This

Babbitt Metal.

quite largely for lining

is

locomo-

qualities.

a soft white metal that Its

shaft-bearings.

is

used

composition

is

melted copper 4 parts, antimony this is and before melted with an addiusing alloy together, tion of twice its weight of tin and applied to the bearings usually as follows:

So the

while molten. 4,

antimony

and

8,

Aluminum. and

A

ductile,

8, tin 24,

real

composition of the lining

is

copper

tin 96.

This

is

a very light metal, soft, malleable,

and of a silvery-white color with a bluish

tint.

it with comparative cheapness was and since then its production has been 1890,

process for producing

discovered

in

It is

rapidly increasing.

thoroughly non-corrosive

e

WROUGHT METALS. These consist

Wrought easily

of

wrought

iron

and

steel of various qualities.

Iron or Malleable Iron

melted and

is

is

a white metal not

very strong and tough.

It is

made from

the white cast irons by abstracting the most of the latter's car-

bon

in a puddling-furnace.

It is

taken from this furnace in

large spongy masses called blooms, and shingled by repeated

squeezing and hammering and rolled into what is known as puddled bars. The puddled bars are then cut into short

DRAWING AND DESIGNING.

34

pieces and piled into faggots; these are heated again and rolled into

what

ties of

known

The

best quali-

iron are piled together, reheated,

and rolled

is

as

merchant

bars.

wrought same way many times, giving the which makes it so tough and strong.

in the

iron its fibrous nature

A

valuable property

wrought iron is that it can be welded at a temperature of from 1500 to 1600 Fahr.

of

This

Case-hardening.

is

a hardening of the surface of

finished parts of machines, such as the links, guides, etc

steam-engines, so that their wearing qualities are very It is effected as follows:

increased.

hardened

is

,

of

much

the piece to be case-

placed in a suitable receptacle and surrounded by

bone-dust, horn-shavings, yellow prussiate of potash, or any

such substance that red heat,

when the wrought

carbon surrounding

it

is

ways

of

some

steel,

of

the

which can

in water.

made from wrought

by adding a little carbon by extracting some of its carbon. There

or from cast iron are three

iron will absorb

and be converted into

be hardened by immersing Steel

carbon, and heated to about a

rich in

is

doing

iron

this: the

Bessemer, Siemens-Martin,

and cementation processes. Bessemer Steel

is

made by pouring melted

converter through which a blast of

way

the carbon in the cast iron

pure

iron.

which

is

To

is

cast iron into a

forced.

In this

burnt out, leaving almost

added a certain quantity of spiegeleisen, a compound of iron, carbon, and manganese, and this

is

then the molten metal

cast into steel ingots'.

is

Siemens- Martin Steel

and

is

air

cast iron,

or

cast

is

iron

made by melting wrought

iron

and certain kinds of iron ore

together on the hearth of a reverberatory gas-furnace.

s

INTRODUCTORY INSTRUCTIONS. The Cementation wrought iron placed

The

in

Process consists of

powdered charcoal

35

embedding bars

in a fire-clay

of

trough and

a furnace for several days at a high temperature.

in

combines with portions of the carbon and forms blister-steel, so called from the blisters found on its surface. iron

Bars of blister-steel about 18" long are then bound together

by strong

steel

hammered and

and heated to a welding heat, then

wire

rolled into bars called shear-steel.

WOODS.

The woods used pine,

fir,

in

machine construction are principally

beech, boxwood, ash, elm, hornbeam, lignum-vitae,

mahogany, oak, and teak. Pine and Fir are strong, cheap, and easy to work, and are largely used for a variety of purposes.

much used

White and Yellow Pine are

Beech

is

pattern-making.

used for the cogs of mortise-wheels;

smooth surface and

Boxwood

is

is

it

takes a

very close-grained.

much used

It takes a

bearings.

in

for sheaves of pulley-blocks

smooth

surface,

is

and

hard, heavy, and of

a bright-yellow color.

Elm

is

very durable in water, and

paddle-wheel

is

therefore used for

floats, piles, etc.

Hornbeam

is

often used for cogs of mortise-wheels.

This is a very hard wood of great Lignum-vitae. For these reasons it is strength and durability under water. used for bearings under water and other purposes requiring hardness and strength. Its specific gravity is 1.33; i.e., i-J times the weight of the same volume of water.

Mahogany

is

a favorite for

making small patterns.

It is

DRA W'ING AND DESIGNING.

36

.

straight-grained, strong, and durable, and does not as readily

change

form when seasoning as most other woods.

its

Oak

tough and straight-grained, very durable, whether It is used for machine-framing and used dry or in water. is.

supports.

Teak little

a strong, tough, durable wood.

is

when

seasoning, and

Bolts passing through it

it

is

It

shrinks very

very valuable on that account.

are prevented from rusting

by the

oil

contains.

STRENGTH OF MATERIALS. DEFINITIONS.

The

Load.

load on any

member

of the external forces acting on

load which the

member

is

it.

of a

machine

The

useful load

a total is

the

designed to carry outside of itself;

on the springs of a railway-car

e.g., the useful load

is

is

the load

which may be placed upon the car in addition to the load A live load is a arising from the weight of the car itself.

and removed continuously. A dead load or constant load is that which has an unvarying and variable load

applied

continuous straining action.

Strain and Stress.

duced by the action

Strain

of a load.

is

If

the change of form prothe load does not exceed

the elastic limit of the material the strain will disappear

the load

is

removed.

Machine-members should be designed

strong enough to resist permanent set under Stress

is

the force which causes strain.

kinds of stress are

:

when

maximum The

load.

different

tensile stress or pull, compressive stress or

IN TROD UCTOR Y INS TR UCTIONS.

37

thrust, shearing stress or cross-cutting, bending or

combined

thrust and pull, and torsional or twisting stress.

Resistance of metal to change of form inherent cohesive force of Elasticity or spring

is

its

is

due to the

molecules.

the inherent property in a material

of regaining original form

after an external load has

been

removed.

The

Elastic Limit.

elastic limit

is

the limit of extension

or compression to which a material can be subjected without

permanent

set.

Within the

elastic limit strain

and

stress are

proportional.

Modulus

of Elasticity.

Dr.

Thomas Young

of

the

Royal Society propounded the following formula for " the modulus of elasticity (E) in 1826, known as Young's " Modulus British

:

E=

stress per sq. in. in Ibs. :

:

.

f

.

the elastic limit). r (within v

strain per inch of length

TABLE

1.

ELASTIC MODULI.

Material.

DRAWING AND DESIGNING. The Proof Strength cause permanent set;

The Factor of a

member

actual

The

nearly equal to the load that will

i.e., to the

of Safety

to the

load.

is

is

maximum

the ratio of the ultimate strength

working load, or the breaking load to the factor

of

safety

materials and for different uses of the of course

much

elastic resistance.

changes

same

for

different

material.

It is

greater under live loads than under constant

dead loads.

The

following table gives the ordinary factors of safety in

general use:

TABLE

2.

FACTORS OF SAFETY.

Material.

INTRODUCTORY INSTRUCTIONS. Strength of

Wrought

The

Iron.

wrought iron is usually over bars and plates will show an

39

elastic

half its ultimate strength; elastic limit of

of

strength

good

about 26,000

Ibs.

In ascertaining the strength of a particular piece of wrought iron

will

it

know

be necessary to

the elongation per cent of

The elongation is greater for short than for long The usual length of specimens for tensile test specimens. specimen.

is

8".

Wrought

of strength

is

iron loses

its

strength in forging; this loss

The

equal to about 20$.

difference

between

the strength of wrought iron when pulled against the grain

and

in

the direction of the grain

is

from 3000 to 9000

Ibs.

per

the strength in the direction of the grain being the

sq. in.,

greater.

The

tensile strength of

40,000 to 60,000

Ibs.

per sq.

Strength of Steel.

The

wrought iron

varies

from

in.

steel cast

from

blister-steel

is

the strongest, having a tensile strength of from 100,000 to

130,000

Ibs.

per sq.

in.,

but

it

elongation of only about 5$. constructive purposes.

A

is

It

hard and is

brittle,

with an

therefore unsuitable for

good plate

steel for steam-boilers

has a tensile strength of from 55,000 to 60,000

Ibs.,

with an

elongation of about 20$ in a length of 8".

The various

worth,

following authorities;

etc.

tables e.g.,

were

compiled

after

consulting

Thurston, Unwin, Kent,

Moles-

DRAWING AND DESIGNING.

40

TABLE

3.

AVERAGE ULTIMATE AND ELASTIC STRENGTH OF VARIOUS MATERIALS AND MODULI OF ELASTICITY IN POUNDS PER SQUARE INCH.

Material.

USEFUL TABLES AND MISCELLANEOUS INFORMATION. WEIGHTS AND MEASURES. AVOIRDUPOIS OR COMMERCIAL WEIGHT. 16 drach'ms 16 ounces 14 28

....

ounce.

SQUARE MEASURE. 144 square inches

pound. stone.

pounds "

4 quarters 2240 pounds

.

I

.

quarter. cwt. ton.

feet

9

I

square foot.

.

.

i

.

.

i

yard. rod.

.

'

30^ 40

'

'

4 '

640

yards rods roods

.

.

i

rood.

.

.

i

acres

.

.

i

acre. mile.

MEASURE OF VOLUME, A cubic foot has An ale gallon has

A A

A A A A A A A

1728 cubic inches. 282

standard or wine gallon has dry gallon has bushel has cord of wood has perch of stone has ton of round timber has "

box igf " i2\l 8i

" "

A A A An

"

hewn

7

6T ,

'

4iff

X X X X X

231 268.8

2150.4 128

40

"

50

. 19! inches, 19! inches deep, contains . " " " " .... I2^f " i2^| " 8 . . 8| " 6 T^ . . 6/g ,

4iV

4yff

feet.

24.75

acre contains 209 feet long by 209 feet broad

.

. .

is

i

barrel.

i

bushel. peck. "

i

i i

quart.

4840 square yards. I

acre.

TABLE OF DISTANCE.

A A A A A A A A

mile

is

... ...

knot is league is fathom is metre is nearly .

hand palm

is

span

is

is

... ... ...

5280 feet or 1760 yards. 6086 feet. 3 miles. 6 feet.

3 feet 3! inches.

4 inches.

"

3

9

MEASURE OF LENGTH. 12 incnes 3 feet , 2

4 rods

i

foot,

i

yard.

yards

I

fathom,

8

feet

i

rod.

3 miles

I

.

10 chains

.

i

furlongs

i

i

chain, furlong mile.

league. 41

DRAWING AND DESIGNING. Each nominal horse-power of boilers requires i cubic foot of water per hour. In calculating horse-power of steam-boilers consider for Tubular boilers 15 sq. ft. of heating-surface equivalent to I horse-power. Flue boilers 12 sq. ft. of heating-surface equivalent to i horse-power. Cylinder boilers 10 sq. ft. of heating-surface equivalent to i horse-power. To find the area of a piston square the diameter and multiply by .7854. To find the pressure in pounds per square inch of a column of water, multiply the height of the column in feet by .434. A horse-power in machinery is estimated at 33,000 pounds raised one foot high in a minute, or one pound raised 33,000 feet high in a minute. Iron under the influence of the hammer and of constant use gradually ,

assumes, by repeated vibration, a different texture from that the piece was new. The metal becomes crystalline, loses

and becomes

it

its

had when tenacity,

brittle.

WEIGHT OF WATER. =

At 62 F. cubic foot at 39.1 F. = 62.425 Ibs., at 212 F. 59.833. the weight varies from 62.291 to 62.360. The figure generally believed to

One

be the most accurate

is

62.355.

Weight

of

i

gallon at 39.2

=

8.3389 Ibs.

WEIGHTS OF CAST-IRON WATER-PIPES. IN POUNDS PER FOOT RUN, INCLUDING BELLS

Diameter.

AND SPIGOTS.

USEFUL TABLES AND MISCELLANEOUS INFORMATION. 43 THICKNESS OF CAST-IRON WATER-PIPE. The following formula, adapted from

Neville, is believed to be a safe equation for the thickness of cast-iron pipe for public water-supply: -

where

t

= d=

h

-32,

thickness of pipe in inches, head or pressure in feet,

diameter of pipe in inches, =, the tensile strength of metal in tons of 2000 pounas. What should be the thickness of a 2O-inch water-main subject to a

S

maximum

pressure of 150 pounds per square inch, or 150 pounds tensile strength

feet head, with cast-iron of 18,000

/

/346.2 9 f =X .ooi6( + -^j-

What should same metal

=

The speed " "

4

41

4^

Speed

~-

at

X

+

.ooW^- +

X

.32

=

"

"

"

"

"

346.2

.9757'-

is

180

.

.

of bolting-reels " conveyers for flour

"

1.6313"

230 to 250 revolutions per minute. 200 .

*'

+ .32 =

40

loj

which millstones should be run

"

41

"

20

=

be the thickness of 4O-inch pipe for same service and of

3-feet stones

3i

" "

X

2.308

?

/

For

"1

\

loj

X ?

"

160

30 to 35 '

.

wheat

.

.

.

.

.

35 to 40

"

"

"

" " "

""

.451050

" " "

elevators

30 to 35 " smut-machines from 550 to 700 revolutions per minute, accord-

ing to size of machine.

For merchant mills allow 20 horse-power to a pair of burrs (4 feet), and the necessary machinery for cleaning and bolting; and for country mills about 10 horse-power to a pair of burrs. For a single upright saw allow 10 horse-power, speed about 150 revolutions per minute. For circular saws the best average working speed is 650 to 700 rev. per min. for 36-in. saw. " " " " " " 60010650 40 " " " " " " 55010600 42 " " " "

500 to 525 lev. per min. for 48-in.saw.

47510500 40010450

52510550 44 A 6o-saw gin requires 6 horse-power

A

to gin 500

sumac-mill requires 15 horse-power.

"

"

"

pounds of

"

"

54 60 "

lint in 2

" "

hours.

DRAWING AND DESIGNING.

44

To reduce for round cores and core-prints, multiply the square of the diameter by the length of the core in inches, and the product by 0.017 i* the weight of the pine core, to be deducted for the weight of the pattern.

SHRINKAGE OF CASTINGS. Pattern-maker's rule should be for

of an inch longer per linear foot.

PROPERTIES OF THE CIRCLE. Diameter X 3.14159 = circumference. Diameter X .8862 = side of an equal square. Diameter X .7071 = side of an inscribed square. Diameter 2 X -7854 = area of circle. Radius X 6.28318 = circumference. Circumference -5- 3.14159 = diameter.

WROUGHT-IRON WELDED TUBES FOR STEAM, WATER. Nominal Diameter.

GAS,

OR

USEFUL TABLES AND MISCELLANEOUS INFORMATION. DIFFERENT COLORS OF IRON CAUSED BY HEAT. Cent.

Fahr.

2IO

410

221

430

256 26l

493

370

680

500

.932

502

(POUILLET.)

Color.

Pale yellow. Dull yellow.

Crimson. )

\

Violet, purple, and dull blue; between 261 C. and 370 C. it passes to bright blue, to sea-

green, and then disappears. to be covered with a light coating of oxide; loses a good deal of its

Commences

much more impressible hammer, and can be twisted with

hardness, becomes to the

ease.

525

977

700 800

1292

Becomes nascent Sombre red.

1472

Nascent cherry.

1657

I4OO

2552

Cherry. Bright cherry. Dull orange. Bright orange. White. Brilliant white

1500 1600

2732

Dazzling white.

QOO 1000 IIOO

1832 2012

1200

2192

1300

2372

red.

welding heat*

2912

TABLE OF DECIMAL EQUIVALENTS OF ONE INCH. 1/64

45

46

DRAWING AND DESIGNING. MELTING-POINT OF METALS, ETC-

Names. Platina

459

Antimony Bismuth Tin.

Lead Zinc

Cast iron

Names.

Fahr.

.

Wrought

Fahr.

iron

2900

842

Steel

487

Copper

2500 2000

475 620

Glass

2377

700 2100

Beeswax

151

Sulphur Tallow

239

TABLE

92

5.

WEIGHT OF VARIOUS SUBSTANCES. RULE. Divide the specific gravity of the substance by 16 and the quotient will give the weight of a cubic foot of it in pounds.

USEFUL TABLES AND MISCELLANEOUS INFORMATION.

47

CIRCUMFERENCES AND AREAS OF CIRCLES ADVANCING BY EIGHTHS. Diam.

DRAWING AND DESIGNING.

47' Number.

USEFUL TABLES AND MISCELLANEOUS INFORMATION. Number!

Square.

47*

47

5

Numbe-

DRAWING AND DESIGNING.

USEFUL TABLES AND MISCELLANEOUS INFORMATION. Number

47

5

Number

DRAWING AND DESIGNING.

USEFUL TABLES AND MISCELLANEOUS INFORMATION. Numbe.

-

4/

DRAWING AND DESIGNING.

47' Number

USEFUL TABLES AND MISCELLANEOUS INFORMATION. Numbe

4 7*

DJRAWING AND DESIGNING.

47' Number

USEFUL TABLES AND MISCELLANEOUS INFORMATION. Number

DRAWING

47'

JNumberj

Square.

AJfD DESIGNING.

USEFUL TABLES AND MISCELLANEOUS INFORMATION. 47 Number

1

47 Number

DRAWING AND DESIGNING.

USEFUL TABLES AND MISCELLANEOUS INFORMATION. 4/ Number,!

Square.

1

47

15

Numbe

DRA WING AND DESIGNING.

USEFUL TABLES AND MISCELLANEOUS INFORMATION. Number

DKA WING AND DESIGNING.

47' Numbe

USEFUL TABLES AND MISCELLANEOUS INFORMATION. Number

N[iiar
4/

47' Number

DRAWING AND DESIGNING.

USEFUL TABLES AND MISCELLANEOUS INFORMATION. Number

47'

DRAWING AND DESIGNING. WIRE AND SHEET-METAL GAUGES COMPARED.

ll IS

K

CHAPTER

I.*

SCREWS, NUTS, AND BOLTS.

A

Screw

is

cylinder and

is

a helical projection or thread forrned upon a

the most

common

device used in mechanical

FIG. 28.

combinations. chinery

for

It is

employed

producing

pressure *

in the construction

contact

and

of

ma-

transmitting

Copyright. 48

AND

SCREWS, NUTS,

When

motion.

the

into

fit

BOLTS.

49

the thread of an external screw

hollow

corresponding

an

of

made

is

screw

internal

latter is termed its nut. (Fig. 28) the The Pitch of a Screw-thread is the lineal distance

nut would advance along the axis in one turn. threaded screw the pitch of

in'

a

its

In a single-

the distance between the centres

is

two consecutive threads measured

axis,

to

screw

double-threaded

in the direction of

it

the

the distance from

is

centre to centre of every alternate thread, and in a triple-

threaded screw

it is

a distance that will embrace three threads.

For screw-fastenings, instead of threads per inch of screw

of giving the pitch the is

for

given

number

example, a bolt

of \" diameter has generally 8 threads per inch; this

wound around

that the bolt has a single thread

every inch of

its

it

means

8 times for

length.

Screws

Right- and Left-handed Screws.

are

made

and left-handed, of which the right-handed are the more common and are distinguished by their nuts advancing right-

along the screws when turned in the direction in which the hands of a watch revolve. On a drawing the right-handed

by the threads

screws are distinguished

towards the

right

position,

as

thread

shown

nut

is

is

in

hand when

When

Fig. 28. in section

inclining

the screws

are in

upwards a vertical

a nut with a right-handed

the direction of the threads in the

the opposite to the threads on the screw.

The Nominal Diameter the tops of the threads and

of a is

cylinder upon which the thread

nominal diameter that shearing strength.

is

Screw

is

the diameter over

equal to the diameter of the is

cut.

considered

It is

the area of the

when estimating the

DKA WING AND DESIGNING.

5O

The

Effective Diameter

of the thread and

nut before

is

the diameter at the bottom

equal to the diameter of the hole in the

Unless when the bolts are

threads are cut.

its

subjected to a shearing stress,

diameter that

is

it

the area of the effective

is

considered in estimating their strength.

is

The Depth

of the

Thread

is

the distance measured

perpendicularly to the axis of the screw from the top to the

bottom

of the thread.

NOTATION.

d= nominal

diameter of bolt;

d^=- effective diameter of bolt;

6

=

depth of thread


p

=

The Forms

V;

pitch of thread

number

n

;

;

of threads per inch.

of Screw-threads in general use in machine

construction are represented in Figs. 29-33. is

adopted on

all

The

V

thread

screw-fastenings because of the shearing

strength of the threads and frictional holding power, which is

due to the normal pressure on the thread being inclined

k

P

H

FIG. 29

to the axis of the screw.

may be

This normal force N, Fig. 29,

resolved into two components, one

L

parallel to the

SCREWS, NUTS, axis of the

L

screw,

AND

BOLTS.

R

and the other

at

5

angles to

right

represents the load carried by the thread and

tending to burst the nut

V

the

of

the

R

1

it.

the force

therefore the greater the angle

;

greater will

be

the

normal

component or

bursting force, and, the friction being proportional to the

normal

V

the forms of

common'use

The which

is

will increase

it

force,

with the angle of the V.

Of

threads shown two (Figs. 29 and 33) are in

in the

United States

for bolts

and nuts.

Sellers or United States Standard, a section of

shown

in

Fig. 29, has been adopted

by the U.

S.

Government, the Railway Master Mechanics' Association, the Master Car-builders' Association, and many of the principal manufactories

in

this

The

country.

of

sides

this

thread

of #, short of form an angle of 60 with each other, and are meeting at a sharp point at the tops and bottoms, which -J-

makes the pitch,

sides of the thread in

length equal to f of the

and the depth of thread d

will

be expressed by the

formula

d

The

effective

relation

sin

60

=

0.65^

(i)

diameter will then be d,

The

=fX/

= d-2d

=d-

i.$p

=d

^.

between the pitch and the diameter

.

will

.

(2)

be ex-

pressed by the formula

p

The number

0.24 1/^_|_ 0.625

of threads per inch

0.175.

(3)

is

I

-

24

Vd

+ 0.625

(4)

0.175

DRAWING AND DESIGNING.

52

of proportions on page 70 has been deduced from the preceding formulae. A difference, however, may be found

The

table

between the formulae and the table

in the

number

of threads

per inch, as the table has been modified to avoid as far as practicable troublesome combinations in the gears of screw-

cutting machines. Exercise

Draw 6

i.

threads in sectional outline, of the

Sellers thread (Fig. 29), suitable for a screw 6"

Scale three times full

diameter.

in

size.

Begin by drawing a horizontal line in the " upper left-hand corner of the paper f down from the border" in from the left-hand borderline, and a vertical line about Construction.

line.

Then

find the pitch

where the two

lines

with the scale on

/ by

you have

the formula

just

drawn

the horizontal line 6

apart equal to the pitch as found these points with the 30

and cut

off

mark

off

points a distance

the formula.

by triangle draw the Vs.

one division

and from

intersect

the pencilling by dividing the depth of the divisions,

(3),

at the top

V

Through Complete

into 8 equal

and bottom of

each thread.

The Sharp V Thread, shown

in

Fig. 30,

is

one of the

FIG. 30.

forms

of threads that

were

in use

before the Sellers thread

AND

SCREWS, NU7"S,

.BOLTS.

53

was adopted as the U. S. standard, and is still used, although condemned by all progressive engineers. This thread is the

same meet

made

as the Sellers thread except that the sides are at a sharp point at

to

the top and bottom, which makes

the sides of the thread equal in length to the pitch/, and of the thread tf, will be expressed by the formula the

depth

d

The

effective

l

=/ sin

=

60

0.866/.

diameter of the bolt

(
.

.

.

.

.

(5)

will

then be expressed

d

1.732.

by the formula

^=d Now, comparing

X

2

o.866/

=

the effective diameters,

.

(6)

:

= di.^p.

U. S. threads

d

V threads

d^ =.

v

we have

.

d

i

(2)

.7 $2p

(6)

This serves to show that with an equal pitch the effective diameter of the screw having a U. S. standard thread is greater than one with a sharp

V

thread.

While the

latter

form

of thread materially diminishes the strength of the bolt, the

sharp point adds very

little

strength to the thread.

ther objection to this form of thread

is

A

fur-

the variation in depth

of the threads due to the wear of the sharp points on the taps dies used in producing them.

and

The Whitworth is

shown

adopted on tion.

It

V

Thread, an outline

section of which

in Fig. 31, is the British standard, all

screw-fastenings in British

has the sides of the

V

to

-J-

of the total

is

generally

machine construc-

inclined to each other at an

angle of 55, and has an amount rounded

bottom equal

and

depth

of the

off at

V.

the top and

The

table oj

DRAWING AND DESIGNING.

54

dimensions for Whitworth screws (page

from the following formulae.

= 0.5

,

The

total

=

cot 27i

7)

nas been deduced

depth of the

o.96/.

V

.

.

.

.

.

.

,

.

(7)

FIG. 31.

The depth

of the finished thread

8

The pitch Number of

=|x

0.96^

= 0.640.

/= 0.08^ + 0.04.

(8)

(9)

threads per inch

=

,

and

p The diameter

at the

p= *

n

bottom of the thread

be given by

will

the formula

^=^

Draw 6

Exercise 2.

thread (F\g.

31).

Construction.

of the Sellers

2

X

= ^- H-.

threads of the

Pitch i".

At a

o.64/

.

.

Whitworth form of

Scale three times full size.

suitable distance below the drawing

thread draw two horizontal lines parallel to

each other and a distance apart equal to 0.96^.

upper

line

mark

(11)

.

off

a distance ab equal to the pitch.

On

the

Bisect

AND

SCXEWS, NUTS,

BOLTS.

55

ab and draw the bisecting line to cut the lower parallel line at the point c.

Join ca and

which

cb,

Mark

other at an angle of 55.

off

will

be inclined to each

the pitch from b along

the upper line, and from c along the lower

required

number

rounding

off

Screw-thread.

The form

invariably called the square thread

is

of thread

to

However,

0.5^.

make

it

is

and

On

made

pitch

of

enough

is

V

one with a

has to

resist

bottom

of the thread that the

As

the shearing action of the load.

usually

thread

;

amount

therefore the square thread will have only half the of material at the

width

screws of the

drawing. square upon same diameter the pitch of a square-threaded screw equal to twice the

its

usual and accurate

the

it

which

a rectangle,

really

the depth of the thread being equal to 0.485^ equal to

to give the

the sharp points of the V.

The Square is

line,

Complete the pencilling by

of threads.

V

thread

the bearing-

surfaces of this screw are perpendicular to the axis, and the force applied parallel

to

it,

there will be no bursting force

upon the nut and as the reaction is nearly equal to the load on the square-threaded screw, there will be less friction than ;

there

is

under the same conditions with a

quently the square thread

is

or

thread

;

conse-

best adapted for transmitting

motion when the load has to be moved

The Knuckle

V

in opposite directions.

Rounded Screw-thread

is

a modifica-

tion of the square thread in which the top and bottom of each

thread are

made

of thread

is

in

semicircular, as

shown

in Fig. 32.

This form

used for rough work and can be readily thrown

and out of gear with a portion of a nut. The Buttress Screw-thread is a combination of the

and square threads, one

side being perpendicular,

V

and the

DRAWING AND DESIGNING. other inclined at an angle of 45

to the axis of the screw,

and has an amount cut from the top and bottom

of each

FIG. 32.

of the total depth of the thread, as shown This form of thread can be used only when the on that side of the thread which is at right angles

thread equal to in Fig. 33.

pressure

is

to the axis of the screw.

FIG. 33.

Exercise

knuckle, and Pitch i".

Draw

3.

the

buttress

sectional

outline of the square,

threads shown in

32 and 33.

Figs.

Scale twice full size.

Pipe-threads

Previous to the year 1862 no

common

system had been agreed upon for the form or proportions that time, owing to the

of pipe-threads.

Since

the late Robert

Briggs, C.E.,

tables for the dimensions of pipes

who proposed

efforts

of

formulae and

and pipe-threads, a standard

SCREWS, NUTS,

AND

BOLTS.

57

TABLE 1. STANDARD DIMENSIONS OF WROUGHT-IRON WELDED TUBES. (BRIGGS STANDARD.) Diameter of Tube.

DRAWING AND DESIGNING.

5*>

n be the number of threads per inch. For the length of tube-end throughout which the screw-thread continues if

perfect the empirical formula used

where out

D

its

is

T=

(o.SD

-j-

4.8)

X

the actual external diameter of the tube through-

is

parallel length,

and

is

expressed

in

inches.

Further

come two having the same the bottom, but imperfect at the top. The remain-

back, beyond the perfect threads, taper at

ing imperfect portion of the screw-thread, furthest back from the extremity of the tube,

system of joint

and

;

its

is

not essential in any

imperfection

is

way

to this

simply incidental to

the process of cutting the thread at a single operation. Exercise

4.

Draw

a section of a pipe-screw (Fig. 34) for

a wrought-iron pipe 8" in diameter.

Scale five times full size.

FIG. 34.

Draw two

Construction.

lines parallel

to each other at

a distance apart equal to the thickness of metal as given the table

;

of the pipe, and from 2 along the line

to T.

Taper I

to

every

32

at

the

pitch,

in

32 means an

units in length.

required

intersects 2

in

then draw the vertical line 2 to represent the end

mark

mark

off 3, 4,

equal

of I unit in height From the point 4 draw the line 5

inclination. off

I

inclination

On

the line

5

from where

it

points at a distance apart equal to the

and through these points with the 30 triangle draw the

AND

SCREWS, NUTS, threads.

The bottoms

of the last

bottom

drawing a line from the full at is

BOLTS.

59

4 threads are cut

of the

last

off

by

thread that

is

the bottom to a point on the surface of the pipe which

beyond the screwed part equal to the pitch. Screw-thread Conventions. The method of drawing

a distance

form

screws to represent their true

but

it

man

is

quite obvious that

it

is

is

shown

in

28,

Fig.

unnecessary for the drafts-

lengthy geometrical construction to perform indicate each screwed piece upon the drawing. Instead he adopts some convention suitable to the class of drawto

ing he

this

is

making that can be quickly drawn and

understood to represent a screw-thread.

Fig.

is

generally

35,

No.

I,

rti

FIG. 35.

shows a convention

V

thread; No.

left-hand

V

thread; No.

3,

for a

a

thread; 6,

any

any thread of very

double

V

thread; No. 2, a single

single square thread;

No.

V

5,

a

No.

4,

double right-hand

thread of small

small diameter.

diameter;

a single

square

No.

7,

The method adopted shown at No. 7. The

on rough drawings and sketches is dotted lines indicate the bottom of the thread, and the distance they extend along

the

piece

the length

of

the

DRAWING AND DESIGNING.

60 screwed

At Nos.

part.

4 are shown

2,

I,

conventions

adopted upon finished drawings to represent threaded screws There are various ways of a large diameter and wide pitch. the appearance

of improving

by shading the lower lines of each 37, and another method is to fill the

side of

shown

thread, as

convention

of this

shown

shown

thread, as

in

is

in Fig.

completely the under

in

Fig.

At No.

39.

method adopted on working drawings

a

one

:

6

is

to represent

screw-threads upon pieces of a small diameter or large screws

drawn to a small top and

When

wide

the

Here the narrow

scale.

lines

the

bottom

lines indicate

of the

the

screw-thread.

a very long screw has to be represented upon a draw-

ing, as

is

often the case with the square-threaded screw, a

few threads are drawn

and the length

at the

of the screw

is

beginning of the screwed part, indicated

by dotted

lines

drawn

from the bottoms of the threads.

The

The most common

Nut.

for producing contact pressure

is

application of the screw

the bolt, used in conjunction

with a nut, of which there are different forms.

most

in use is

The standard

proportions for hexagonal nuts are

H= height = diameter of bolt F= D=

The form

the hexagonal (Fig. 37).

distance across the

flats

=

distance across the corners

:

(d).

it^/+ i

=

(ij^

of an inch.

+

-g-")

1.155.

Fig. 35 shows the true form of the curves when the end of the nut is machined to form a part of a sphere or cone.

This rounding or bevelling fering. 2
The

and the angle a

the nut.

off of the corners is called

radius r of the chamfering

When

is

made from 60

is

to 45

representing nuts upon a

cham-

made from i^d

to

with the axis of

drawing they should

SCREWS, NUTS, always be drawn

to

show

AND

61

BOLTS.

the distance across the angles, as in

Fig. 40

Exercise 5.

Draw

a bolt 6" in diameter

the true curves of a hexagonal nut for

when the top

of the nut

is

chamfered

FIG. 36.

form a part of a sphere with a radius r = I J times the diameter of the bolt (d), and when the chamfering is a part off to

DRA WING AND DESIGNING.

62

makes an angle

of a cone the side of which

shown

axis-of the nut, as

Begin with the plan, first locating the cenas a centre and a radius equal to %d draw

Construction. tre

c,

and with

with the

of 45

in Fig. 36.

c

the quadrant representing the hole in the nut, and from the

same centre and a radius equal to half the distance across the flats "F draw the quadrant Q, and on this quadrant circumhexagon with the 30

scribe a part of a

as

shown

in

37.

Fig.

views, and with r

.

Draw

as a radius

triangle

T square,

and

the part elevations and end

and the centre on the centre

which represents the spherical chamfer, and on the lower elevation draw the angle a. Divide eb into line

draw the

any number

arc 5,

of

Where

perpendicular lines

the arc

5 and

12,

13,

draw

line

L

and with

arcs,

at points

divisions, say 6,

draw the horizontal

c as a centre

and

4,

3,

5^.

intersect

lines 7, 8, 9, 10,

radii ci, c2,

draw

c^,

1

1,

^4, c%

vertical lines to intersect the lines 7, 8,

These points of intersection

9, 10, etc.

To

face will be an arc of a circle.

view draw a

line

1

left

through the points

of the

14 and line

;

15

15

curve of the front

find the curves

on the side

I,

2, 3,

perpendicular line

14

half

end view; where the arcs drawn etc.,

inclined face of the nut in plan sect the line 14

be points of the

say i" below and parallel to the lower

5

face of the nut in plan, and a

an inch to the

will

The

curve on the side face of the nut.

on to the

2,

and from where these arcs intersect the inclined-

face of the nut

lines

I,

drawn through these points

from the centre

draw horizontal

and with a centre

c cut the

lines to inter-

at the intersection of the

revolve the lines 17, 18, 19, 20, 21, 22, 23

and draw perpendicular

points of intersection.

The

lines

line 17 revolved will

through the be the cen-

SCJ!tTS, NUTS, tre of the

AND

BOLTS.

63

nut face on the end view, and the intersection of

the lines 17, 18, 19, 20, 21, 22, 23 with the horizontal lines 7, 8, 9,

10,

n,

quired curve.

12, 13 will

be points on one half of the

To complete

re-

the curve, with a centre at the

and the top of the nut mark with the compasses corresponding points on the other side of the intersection of the line 17

line

17-.

FIG. 37.

A

Conventional Method of representing large nuts on In this representation the drawings is shown in Fig. 37. curves of the nut

chamfered

off at

are arcs of

an angle of 45

circles

and the corners are

to the axis of the nut.

DRAWING AND DESIGNING. Draw

Exercise 6.

diameter.

bolt

3"

in

flats

circle

\\d-\-

equal in di"

on this

;

with the set-square circumscribe a hexagon, and find

the centre of the side faces in the elevation and end view of the

With

a

Begin, as in the last exercise, by drawing

Locate the centre and draw a

ameter to the distance across the circle

for

Scale full size.

Construction.

the plan.

views

three

the

centre a and radius

r'

manner shown.

Draw the

hexagon without the curves.

equal to

w

draw the arc

of the

middle face tangent to the top of the nut, and with centre b> and radius r equal to d draw the arcs 3 to intersect the lines I

and

2.

These points

the arcs of the side face. of the curves ing.

of intersection will be the centres of

The method

on the end view

is

of finding the centres,

clearly

shown on the draw-

Through the points where the outside diameter the

bolt intersects

draw the

top

of

the

nut with a radius

arc representing the bolt-point.

/

FIG. 38.

of the r*

=d

SCREWS, NUTS,

When

BOLTS.

65

representing small nuts or nuts drawn to a small is

it

scale,

AND

usual to

make the

distance across

the angles

= 2d.

This method does not give the correct proportions and should only be used on nuts and bolt-heads when d is than i" in diameter when drawn to scale.

less

are chamfered

on the upper side only,

it

When

nuts

usual to cut

is

the cprners parallel to the axis, thus leaving a cylindrical projection on the under side, which bears on the piece the

nut

is

shown

holding, as

in Fig. 39.

FIG. 39.

The diameter

of the cylindrical projection

distance across the Exercise 7

flats

Draw

(\\d-\-

is

equal to the

").

a hexagonal nut for a bolt J" in diam-

eter chamfered on the upper side and finished on the side

as

angles

shown

=

Fig. 38.

in

Fig.

39.

Make

under

the distance across

the

2d, and draw the curves by the method shown in

Scale full size.

Construction.

Draw

the semicircle

i,

2

and divide

it

into

DRAWING AND

66

DESIGNING.

three equal divisions at the points

i,

2, 3, 4;

through these

points draw perpendicular lines to intersect the top of the

The method

nut.

of finding the centres of the arcs of the

side faces will be clearly understood from Fig. 38, where r

each case

is in

=

d.

Machine fastenings are most commonly effected by means of bolts, keys, or rivets. When two or more pieces have to be held together with the intention of disconnecting them again, a bolt or key

the connection

used; the rivet being used only

is

to be permanent.

is

when

The most common form

FIG. 40.

01 oolt used in general machine construction

headed

bolt

shown

Exercise 8.

is

Draw

a hexagonal headed

in

diameter.

Construction.

Make

First

should be clear of the

be

at least

-J".

in

the bolt

Scale full size.

draw the

thickness of the pipe and flanges.

lialf

and nut

bolt

position on a cast-iron pipe-flange (Fig. 41).

y

the hexagonal,

in Fig. 40.

fillet

about

J-"

lines

The

representing

angles of the nut

and the radius

Therefore, the distance

(b) will

the distance across the angles of the nut

give the flange a proper

finish,

the

-\-

the distance (a)

(r)

should

be equal to

^" is

-\- r.

To

made

frorr,

SCREWS, NUTS,

AND

BOLTS.

O/

J" to J" greater than half the distance across the angles of the nut. The number of threads per inch will be found in Table 8.

FIG. 41.

The Square-headed than the hexagonal and

Bolt. is

Fig. 42

is

a cheaper

make

generally used in structures

of

rough iron. It is sometimes, however, adopted in machineand engine-construction generally when the head is let into a recess, as

shown

in Fig. 42.

It

is

used

in

this instance in

preference to the hexagonal head, because

make the square shown give

in

a

recess

in

the pattern.

it

is

easier to

In Fig. 42,

it

is

combination with a square nut, the sides of which

better

gripping surface

for

the

wrench than the

hexagonal, but the latter can be screwed up in a more confined position, as

angle of

two

60

parallel

it is

only necessary to turn

it through art wrench or spanner on to the next while the square nut has to be turned

to get the faces;

through an angle of 90 under the same conditions.

DRAWING AND DESIGNING.

68

TABLE UNITED STATES STANDARD OF Screw-threads.

Diameter of

Screw.

SCREWS, NUTS,

AND

BOLTS.

69

8.

SCREW-THREADS, BOLTS, AND NUTS. Heads.

Nuts.

M. ---

X

X

5/i6

37/64

19/32 11/16 25/32

7/16

X

7/10 10/12 *

5/16

7/16

64

%

i

31/32

9/16

Dn!l.

FM

-1

63/64 9/10

Tap

19/64 11/32 25/64 7/16 31/64 17/32

23/64 13/32 15/32 17/32

23/32 13/16 29/32

27/32 31/32

311

I

311

2tf

3

2

J/

2X 2X

$

3X

4H Mi

4ff

2X 2X 2X

5}i

\y.

2||

3X

3X 4

3 TV

4X 4X

4X

3X

4X

3H

7M

Ix

8

!ft

%

4H

sX

6

sizes are:

4 3 4T T

Tiff

6

/f=^-

sS

DRA WING AND DESIGNING. Exercise

shown full

in

9.

Fig.

Draw a bolt with a square Make the bolt i'' in 42.

diameter.

Scale

size.

The proportions

Construction.

heads and nuts 8.

head, and nut, as

The

will

radius (r)

and tangent

be found is

in

of

Table

made equal

to

F

to the top of the nut or

head.

A

Stud-bolt

screwed at

of

consists

a

bar

both ends (Fig. 43), one

end being screwed into the piece upon is made. The

which the connection other piece

is

then passed

studs and secured by a nut. the nut

make

to

length of the

always be

body

less

a

tight

over the

To

allow

than the thickness of

the piece into which

it

passes.

Studs are used only when impossible,

the

joint,

or plain part must

it

is

or at least very inconve-

nient, to use an ordinary bolt.

When

FlG

-

42.

studs are screwed into cast material, the screwed part should

extend into the metal at

least

ij times their diameter,

and

FIG. 43.

should never

be allowed to bear on the bottoms of the shows a stud used to secure the cylinder-cover Fig. 44

holes. (c)

to

SCREWS, NUTS.

AND

BOLTS.

DR FIG. 44.

DRAWING AND

72

DESIGNING.

Studs are preferred to bolts for this purpose because the flanges can be made very much smaller, and the

the cylinder.

cover can be removed and replaced without disturbing the

A

cylinder-lagging.

stud should not be placed nearer to the

measured

edge of the metal than a distance equal to (d)

from the centre of the stud, and usual to

make the

in steam-tight joints

distance (a) equal to \\d, as

it

shown

is

in

Fig. 44-

the form of stud in general use.

Fig. 43 shows

made

The

and equal in diameter As the weakest part of the to the diameter of the screw. stud is at the change of section, the form of stud shown in

body

of this stud

Fig. 44,

if

is

cylindrical

subjected to a greater stress than

stand, would break

off,

it

could with-

leaving the screwed part in the metal,

but by cutting a semicircular groove of a depth = the depth of the thread on the end of the body that comes in contact with the piece into which the stud is screwed, as in Fig. 43, this part is strengthened and the stud would then break

where the upper screwed part joins the body. The broken stud can then be easily removed by means of a pipe-wrench.

FIG. 45.

In Fig. 45, the stud has a square body which serves as a shoulder, against which the stud

menrs

of a

may be

screwed up tight by

wrench applied to the square

part.

Studs with

round bodies are screwed into position by means of a tool

SCREWS. NUTS,

this consists of a

called a stud-nut;

internal screw, as

AND

shown

in Fig.

BOLTS. long nut

To

46.

73 fitted

with an

avoid damaging the

FIG. 46.

point of the stud, the bottom of the screw in the stud-nut lined with copper.

By applying

is

a wrench to the stud-nut,

the stud can be screwed into the tapped hole in the metal

The

by the plain portion on the stud. nut can then be removed by a quick turn back. until stopped

Exercise flange,

head

a section

it

of a steam-cylinder end-

of securing the cylinder-cover or

to the cylinder (Fig. 44).

When ing

Draw

showing the method

(c)

which

10.

a bolt-head

is

of

Scale full size.

such form, or in a position in

cannot be held with a wrench to keep

when screwing up the

stud-

nut, the bolt

is

it

from revolv-

provided with some

DR

FIG. 48.

FIG. 47.

The

device in the body to overcome the difficulty. or button-headed bolt,

shown

in Fig. 47, is

square part under the head, which hole

in the material

through which

fits it

spherical

provided with a

into a corresponding passes.

Another de-

DRA WING AND DESIGNING.

74

same purpose is shown in Fig. 48 this is and consists of one or two projections forged on the neck of the bolt and made to fit a correspondingly sign used for the

;

called a snug,

shaped hole

in

the metal.

Fig. 49 shows a bolt with a countersunk head and nut.

The

bolt

kept from revolving by a pin

is

into a hole drilled in the

body

The

projecting part of the pin

it.

The nut

is

used in screwing half the

amount

(/),

which

driven

is

of the bolt close to the head. fits

into a recess cut to receive

provided with holes to receive the spanner up, and

it

of metal

may be made

equal in diameter to

between the bottoms of the threads

FIG. 49.

and the outside of the nut.

made

.2$ of

the pin (/) pin (/) lost

is

when

The depth of the nut. The

the holes

may be

H, the height of projecting part of made and The usually equal to .25^. square

is

sometimes screwed into the bolt to avoid the bolt

is

The T-headed

its

being

withdrawn.

Bolt shown in Fig. 50 has the sides of

the head level with the square neck or body of the bolt, and is

used where there

is

not sufficient room to use bolts of the

A

hexagonal or square-headed form. this form of bolt is shown in Fig. 50.

common

application of

SCREWS, NUTS,

The Tap-bolt shown out the use of a nut.

AND

bolt

75

makes a fastening with-

in Fig. 51

The

BOLTS.

is

screwed into a tapped

hole in one of the pieces to be connected, while the head

FIG. 50.

FIG. 51.

presses on the other piece.

This form of bolt

is

used

place of a stud where the piece to be connected could not,

in if

studs were used, be passed over the projecting studs, as in a pipe-fastening where two of the faces are at an angle to each other.

There

is

no standard

for the

foregoing bolt-heads and

nuts, but the following proportions are in general use:

h Exercise

= n.

.7d,

H=d,

Draw

n

=

.6d,

I

=

\\d.

a spherical or button-headed bolt with.

a square neck; and a head with a snug on the neck, as shown A countersunk- headed bolt with a counterin Figs. 47 and 48. sunk nut as shown

in Fig. 49, a

T-headed

bolt

with a square

DRA WING AND DESIGNING.

76

neck,

shown

as

in

Make d

Fig. 51.

Hook-bolt.

in

Fig.

50,

each case

and a

=

tap-bolt,

shown

in

Scale full size.

i".

This form of bolt

as

used where

is

it

is

im-

possible or undesirable to have bolt-holes through one of the connected pieces. A common application of this bolt is

fastening pieces (such as hangers) to flanged beams, as in Fig.

To keep

52.

shown

the bolt from turning, the body

is

DR

FIG. 52.

made square

in cross-section

and passes into a correspond*

ingly shaped hole in the connected piece.

the screw

is

The diameter

of

equal to the square body.

Exercise 12.

Draw an ELEVATION

of a hook-bolt, fasten-

ing a piece to a flanged beam, as shown in Fig. 52, and

PLAN full

of the bolt only, looking

size.

down on

the bolt head.

Scale

,

Tapered Bolts

AND

NUl'S,

BOLTS.

77

where

are used to facilitate fitting

necessary that the bolt should be a perfect that Fig. 53 shows a tapered bolt

is

fit

it

is

in the hole.

common use in the As coupling-

in

of steamships.

couplings of propeller-shafts bolts have only to resist the shearing force, caused by the

on the

strain

twisting

on the

the diameter

shaft,

diameter of the bolt

the

is

where the two flanges come to-

line

Ttd*

gether, and

As

its

f

equal to

s

.

the screwed part of the bolt has only to resist the

tension due to

screwing up,

diameter than practice,

the

small

this part

end

diameter of the

the

made equal

y to

is

strength

to

of

made

is

the

smaller in

tapered

screwed

part

part.

is

In

generally

and the height of the nut from

,

J" less than the diameter of the screw.

The advan-

tages gained by using tapered instead of parallel bolts for

couplings are:

they can be made a perfect

which

that

insures

the

different

easier withdrawn,

better alignment, are

diameter of the screw being eter at

much

the junction of the shafts

can be eter), the flanges Exercise

13.

lengths

Draw

made

fit

of

in

the hole,

shaft

are

in

and, owing to the

smaller than the diam(i.e.,

the effective diam-

smaller.

a tapered bolt

for

a

marine shaft-

DRAWING AND DESIGNING.

78

coupling, showing a part of the shaft-flanges, to the dimenScale half size.

sions given in Fig. 53.

Draw

Construction.

the centre line of the bolt, then the

showing the junction of the mark off the diameter of the bolt.

line

and on

flanges,

From

this line

the point (a) draw

the line ab 12 inches long and parallel to the axis of the bolt,

and from b draw

be perpendicular to ab

and T3^- // long,

which makes the required taper. The radius equal to the diameter of the bolt at the large end.

join ac

Exercise

Draw

14.

3

is

a tapered bolt as in the preceding

and making the

exercise, leaving off the parts of the shafts,

diameter of the bolt

(r)

inches, and the length of the body

Scale half size.

equal to 8 inches.

Foundation-bolts.

This class of bolts

is

for

employed

fastening engine- and machine-frames to stone, brick, or concrete foundations.

The

Rag-bolt (Fig. 54). This form of bolt is fastened to stone by cutting a Lewis hole, which increases in size as it

The

descends.

small end of the hole

is

made from J"

\" larger than the large end of the bolt-head. bolt-head

is

placed in the hole, the space between

sides of the hole

is

filled

to

After the it

and the

with molten lead or sulphur, thus

securing the bolt firmly in position.

The frame

a projecting foot through which a hole

is

cored.

is

cast with

This foot

passes over the foundation-bolt and the engine- or machine-

frame is held in position by the pressure of the nut. d -\- \" diameter of the hole through the foot is .

diameter of the washer ness

3

washer

of d. -\- -f".

The

The

w

is

equal to 2d

distance a

is

=

-f-

The The

\" and the thick-

half the

,

diameter

section of the bolt-head

is

of the

oblong and

SCREWS, NUTS,

FIG. 54-

4ND

BOLTS.

79

DRAWING AND DESIGNING.

8O purposely

made rough and

jagged, which obviously increases

the resistance the bolt offers against being withdrawn from

The

the hole.

length

L

of the

head

(h)

is

usually

made

6d and has a taper = \^" per foot. Exercise 15. Draw a rag-bolt in elevation and plan with a cast-iron of engine-frame as shown in Fig. 54, part

equal to

a

making (d)

i-J-"

in

diameter.

Draw

Construction.

Scale full size.

the centre line and the line repre-

senting the top of the stone foundation, then

mark

off to (b)

the distance which the beginning of the head is below the level of the top of the foundation, and from the point (b) find the taper on one side of the axis in the same manner as

Make the top of the hole de J" greater than of the end the large bolt-head, and through (e) draw a line parallel to the side of the bolt-head be, which will represent in

Exercise 13.

To complete

the edge of the hole.

the other side of the

bolt-head mark off with the dividers equal distances on the other side of the centre

The Lewis

Bolt,

line.

shown

in

cases, in preference to the rag-bolt,

more

easily

the key K.

removed, which

The

is

55,

Fig.

is

because

in

some

can be

much

used, it

accomplished by withdrawing

side be of the bolt-head

(Ji)

has a taper of

Ij" per foot, while the opposite side is parallel to the axis The length L of the head may be made as in of the bolt.

the design of the rag-bolt, equal to 6d. In Fig. 55, the bolt

shown

in

through laterally.

the last

is

shown holding down the pedestal

Fig. 54, page 79. is

rectangular,

to

The allow

hole that the bolt passes

the

The proportions of the washer The thickness (t) of

exercise.

to

pedestal are the

same

the key

is

move as in

made

SCREWS, NUTS,

AND

BOLTS.

3i

D.R. FIG. 55.

DRAWING AND DESIGNING.

82

to allow the

end of the bolt-head to pass through the small end of the hole i" f r clearance, and " should from to \" up from the bottom of the point stop sufficient

large

+

the hole.

and

its

The

thickness equal to

Exercise

ing the

length of the key-head

method

to 2/,

t.

Draw an ELEVATION

1 6.

made equal

is

of securing

it

of a

Lewis bolt show-

to the foundation, a section of

PLAN showing the shape of the hole bolt Draw also an which the passes, as in Fig. 55through END VIEW of the bolt leaving out the foundation-stone and

pedestal-base and a

Make d = 2"

pedestal-base. Construction.

previous exercise.

Proceed

The

in

diameter.

manner

the same

in

distance

longitudinal

+

".

e= -+2

Make

movement, r

as

(a) in this case

+ the

equal to the diameter of the washer (w) a f'

movement

Scale half size.

the

longitudinal

/=^+

t

in

should be

half

the

"W

=

\-

J"'.

Anchor-bolts passing through the foundation are recommended in preference to the rag or Lewis bolts wherever it is

The heads

possible to use them.

are

made removable,

so

that the bolts can be inserted from the top, and are either

under the foundation or

The

in a recess

on the

simplest form of removable head

is

a nut upon the lower end

after the bolt

driving a split pin through

it

The

to keep

it

side, as in Fig. 56.

made by screwing is

objection to this form of head, however,

cannot be removed without difficulty after place long enough to rust.

form of removable head

The

in position

and

from working loose. is it

that the nut

has been in

usual and most suitable

for this class of foundation-bolt is

SCREWS, NUTS,

FIG. 56.

AND

BOLTS.

DRA WING AND DESIGNING.

84

shown

in

square

in section,

cotter

nut

C

Fig,

is

In this design the head end

56.

fitted.

being screwed up by the square end

is

from working out of place

As

it

is

the strength of a bolt in tension

The

this extent

a

C

provided with gib-heads at

area at the bottom of the thread, the

be reduced to

into

the cotter

fitting

To keep

corresponding hole in the washer W.

the ends.

made

is

and has a rectangular hole into which the The bolt is kept from turning when the

body

without reducing

proportions of the cotter

is

due

to the

of the bolt

its

may

strength.

and the bolt-end through

which the cotter passes are

b l for shear would

=

,

but owing to the uncertainty of the

longitudinal shearing resistance of the material, practice to

The and

make

it is

equal S, which insures ample strength.

it

length / of the cotter should not be less than is

usually

the washer square.

made

When

=

25+ J"

3^, which gives a better support to

The washer

W.

usual in

W

is

usually

made round

or

round, D, the diameter, will be found by the

formula

D =
from which

The

value

of

f

c

factor of safety of 20.

may

be

+S + 1".

-J*.

taken

=

Take the value

4 tons and allow a

of

f

t

in this case

=

7

AND

SCREWS, A UTS, 7

tons per square inch.

from

The

BOLTS.

8$

thickness T'oi the washer

is

made

d^ to \\d.

Draw an ELEVATION

Exercise 17

of an anchor-bolt for

securing an engine-frame to a stone foundation showing the

frame-foot and stonework in section; the top stone of sand-

stone and the under part of brick.

Make

END VIEW Make d ij-",

also an

of the bolt-head with the cotter in section.

L=

a

= d + i", e =

2d

+f

Scale half size. forms of which are shown Cap-screws, the different 6' o",

are

57

Fig-

employed

" is

reason for the

name "

cap-

that they are used for fastening on caps or covers

on machinery, such

The Length head,

The

in

screwing two

like the tap-bolt for

or more pieces together.

screws

.

as the caps of journal-bearings, etc.

of a cap-screw

is

the distance under the

excepting the flat-headed form, which

thickness of the head in the length.

The

includes the

angle of the cone

about 76, the sides making angles of 52 with the top, but it is usual to represent the heads on the drawings with the sides making an angle of 60 with the

of the flat-headed screw

is

top.

The

height of the flat-headed screw

is

=

.7 of the

screw

The height of the button-headed screw = .6 of The width of the saw-cuts on the heads screw diameter. = .2 of the screw diameter. The other proportions are

diameter. the are

given

in

Table

9.

Collar-screws are used for the same purpose as capscrews.

The

collar

bearing-surface

through diameter.

the

for

under the head, Fig. 58, gives a larger the head and is used where the hole

connected

piece

is

larger

than

the

screw

.DRAWING AAD DESIGNING.

86

TABLE

9.

CAP-SCREWS. (WORCESTER SCREW

Co.}

Hexagon and Square Heads. Diameter of screw

f

Threads

|

\

to inch f

SCREWS, NUTS,

AND

BOLTS.

CAP SCREWS.

FIG. 58.

Set-screws are employed to hold parts of machines in place by setting the point of the screw against the object to be held.

DRAWING AND DESIGNING.

88

The Holding Power by G. Lansa, A.S.M.E.)

of Set-screws.

In

tests

(made

of the holding

power of set-screws shafts means steel of wrought-iron to for securing pulleys by screws with points of the form shown at Nos. I, 2, and 3 (Fig. 59). It was found that the round-pointed form (No. i), with the radius of the point equal to about the diameter of the screw, had the greatest holding power.

The cup-point

which was case-hardened, held well while the edges were sharp, but the holding power decreased after the first (No.

2),

because of the edges becoming flat. This serves to show that to get good results with this form of point the

test

screw must be piece is

it

is

of a harder material than that of the

holding, and should not be used where the point

subjected to excessive wear.

The length is

made

of the

to the diameter of the screw.

equal

the round and

diameter point

=

head and the distance across the

at the

flat

pivot-points (No.

bottom

from >%d to

set-points

is

d.

usually 45

Strength of Bolts.

8)

flats

The diameters

of

are equal to the

and the length of The angle of the cone and hanger of the threads,

or

60.

In an ordinary bolt with a

V

thread

two or more pieces together by the employed pressure due to the screwing up of the nut, the bolt would yield (i) by tension combined with a torsional stress due to for holding

the friction between the threads of the nut and those of the bolt.

This combination of tension and torsion causes the

bolt to part where the thread ends,

change of section

;

because of the rapid (2) by shearing off the threads; (3) by

shearing off the bolt-head.

Comparing

(i)

with (2)

it

will

found that the shearing strength of the thread on the nut

be is

AND

SCREWS, NUTS,

BOLTS.

II

FIG. 59.

SET-SCREWS. "No. 44

I.

Regular round point,

2.

Cup

1

Flat

4. 5.

Cup Round

6.

Cone

* 4

44

point, set.

5. 44

Diameter of screw

Threads to inch

1

f

j

|

set.

"

"

headless. point, headless.

No. 41

7.

8.

" 9. 44 44

10.

ii.

Flat, pivot point.

" Round, " Hanger, set Cone point. Necked style.

89

DRA WING AND DESIGNING.

90

equal to about twice the strength of the section at the bottom of the thread, but in practice it is found that when the

depth of the nut

is

made

less

diameter, the threads are injured. face-joints

than

of the

.7

on vessels subjected to internal pressure, depend

upon the care exercised by the workman

to leave sufficient

strength to withstand the pressure after the bolt up.

As

bolt

Bolts or studs used for

the

amount

of

strength left

is

is

screwed

an unknown and

uncertain quantity, the stress upon the bolts calculated from

the internal pressure should be kept very low, and no facejoints, unless very small ones, in

diameter.

should have bolts

less

than

-f"

In permanent joints the stress thus calculated

per square inch of section of bolt at the bottom of thread

should not exceed 6000

broken the

Ibs.

stress should

;

and

for bolts in joints frequently

be as low as 2000

Ibs.

Thus


,

the diameter at the bottom of the thread, to withstand the required pressure, will be found by the formula

= area of exposed surface in square / = the pressure per square inch; n = the number of bolts; f = the strain per square inch; a

inches;

t

Unwin's formula

for cylinder-bolts or studs

is

AND

SCREWS, NUTS,

D = the

BOLTS.

9$

diameter of the cylinder;

= the pressure per square inch; n = the number of bolts. f = the strain per square inch = 2000 /

diameter of the cylinder

4000

is

Ibs.

10" or

when the less,

and

when above.

Ibs.

Cylinder-cover and steam-chest cover-bolts should be of soft steel.

Bolts of Uniform Strength. When a bolt in tension is subjected to irregular strains and heavy vibrations, it is made

and stronger by making the area of the cross-section of the unscrewed part equal to that of the screwed part at lighter

This

the bottom of the threads.

down

obtained by turning

the bolt-body to the same diameter as the screwed part

at the fit

is

bottom

of the threads, leaving a part at each

end to

the hole, as shown in Fig. 60.

FIG. 60.

Another method adopted where bolt .should

fill

the hole

it

is

fitted

it

is

into,

necessary that the is

to drill a hole

through the centre of the bolt from the head up to where the screw ends, as shown

The diameter

in

Fig. 61.

of the hole

is

found by the formula

* = ^' -

4".

05)

DRA WING AND DESIGNING.

92

where

= diameter of the bolt; d = outside diameter of the bolt-body; d = the diameter at the bottom of the thread, d.

v

D.R. FIG. 61.

The

Nut-locking Devices.

pitch of the threads on screw

such that nuts subjected to constant pressure will not slack back because of the frictional holding power fastenings

is

between the threads of the nut and those

of the bolt

com-

bined with the friction between the bearing-surface of the nut and the piece it is fastening. If, however, the pressure is intermittent and there is much vibration, the nut will slack

back when the load on

it

has been sufficiently reduced to

allow the vibrations to overcome the friction which opposes

Consequently, wherever a screw is vibration and a varying load, the nut will

the turning of the nut.

subjected to

much

gradually slack back and allow the connection to unless

some locking device

is

work loose

used to keep the nut from

rotating backward.

A Jam-nut device.

down on

This

is

the simplest and most frequently employed

is

simply a second nut

the top of the lower nut

L

N

(Fig. 62) screwed

as tightly as possible,

and the lower nut turned back to cause the threads nut

N to press

upon the under

side of the threads

bolt, while the threads in the nut

L

in

the

on the

press upon the upper

SCREWS, NUTS, of

side

the

AND

Hence

bolt-threads.

BOLTS. slack

all

threads of the bolt and those of the nuts

is

93

between the

taken up and the

nuts will have a frictional holding power independent of the

FIG. 62.

By this arrangement the load on the on the bolt carried upper nut, which should be the larger. In practice, however, the thin nut is often put on the top tension on the bolt. is

because when screwed to turn

it

down

first it

without disturbing the upper nut, the ordinary

spanner or wrench being too thick.

make

many

requires a special spanner

The

general rule

is

to

the thin nut equal to half the diameter of the bolt, but engineers

use two

ordinary

nuts,

thus making the

height of the nuts equal to twice the diameter of the screw. Others again make a compromise between these methods and

make the height of each nut equal to J of the screw diameter. We recommend the latter method and have used these proThis method of portions wherever jam-nuts are shown.

DRA WING AND DESIGNING.

94 locking

too cumbersome to be used on large-sized nuts.

is

employed on nuts over

It is rarely

by

is

reduced.

It

j."

in

diameter.

This consists of a single

Spring-washer Nut-lock.

NL, Fig. 63, which keeps the nut

of a steel spring,

slacking back,

i

its

is

elasticity,

when the

TV"

coil

from

tension on the bolt

employed quite extensively

in

railway-

engineering practice for securing nuts subjected to the heavy

common

vibrations in Fig. 63

and

is

is

that

employed

made by

home

inclined

is

the

to secure the nuts

manufactured by them.

washer

The form shown American Brake Beam Co.,

to this class of work.

^

on the bogie frames,

etc.,

In the cross-section the top of the

of an inch,

and when the nut

is

screwed

under side conforms to the part of the washer

its

contact with

it.

The

in

following proportions agree approxi-

mately with the washers manufactured by the afore-mentioned

company The outside diameter :

the nut

+ TV".

= F the

distance across the

flats of

SCREWS,

NUTS AND t

BOLTS.

95

The inside diameter = d the diameter of the bolt -fThe mean thickness / is equal to the width w. Exercise 18. Draw an elevation of a spring-washer lock before the nut

Make d

=

is

screwed down, as shown

i" diameter.

half

way

across.

nut-

Fig. 63.

Scale twice full size.

Wiles's Nut-lock, shown

sawn

in

-J-".

in

Fig. 64,

After the nut

is

is

an ordinary nut

screwed

home

the

FIG. 64.

opening

is

partly closed

by the screw

5,

which causes the

threads in the upper part of the nut to clamp the correspondThe thickness t of the clamping ing threads of the bolt.

DRA WING AND DESIGNING.

c> part of the nut

may

be

made

equal to twice the pitch of the Z7*

threads.

F=

The diameter

distance across the

diameter of bolt.

under i"

As

of

flat

there

the

screw

sides of the nut, is

^/

5

,

and

*/

where

nominal

not sufficient room on nuts

diameter to use a set-screw, they are locked by partly closing the saw-cut with a hammer blow before the nut is put upon its screw. in

FIG. 65.

Nuts Locked by Means of Set-screws. The ments shown in Fig. 65 are used on quick-moving

arrangeparts of

AND

SCREWS, NUTS, machines.

when

ive

They

subjected to the worst conditions.

which

fits

97

are neat in appearance, simple,

lower part of the nut tion

BOLTS.

is

and

effect-

In Fig. 65 the

turned to form a cylindrical projec-

into a corresponding counterbore in one of the

pieces connected

by the

Through the

bolt.

latter passes

a

set-screw S, the point of which presses on the bottom of the

groove cut upon the cylindrical projection, to keep the burs raised by the set-screw from interfering with the nut being

removed.

The

= 5=

//"

d -\-

5;

=

d\

G= diameter

J"; ''

\d -f

F= /

follov/ing proportions agree with general practice:

of set screw at

the bottom of the threads ;

;

= if -f'; r = half the distance

across

the angles of the nut-J--J".

In addition to the locking device

on quickmoving parts, to extend the bolt beyond the nut. This it

is

usual,

extension E, called a pin-point, has the threads cut hole drilled through

it

into

which

is

fitted

off

and a

a split pin SP.

This renders the nut secure against coming off, but does not necessarily prevent its slacking. The diameter of the split

pin

SPis .05^+

split pin,

method

of

d

l

=

drawing

Exercise 19.

.13,

/=

2j times the diameter of the

diameter at the bottom of the threads. split pins

Draw

is

shown

A

in Fig. 69.

a plan, front elevation and end eleva-

tion of the locking arrangement,

shown

in

Fig. 65, showing

the application of the arrangement on a connecting-rod end of the form shown in Fig. 66. Make d Scale half 4^".

=

size.

DRA WING AND DESIGNING.

98

Locate the centre

Construction.

draw the hexagon

lines,

and the part of the connecting-rod end in plan. far as

we can proceed without

This

Draw

the elevation.

is

as

the part

connecting-rod in front elevation and complete the

of the

locking arrangement, projecting the parts already drawn in

Taking our measurements from the plan, and projecting from the front elevation, we can complete the end We can now complete the plan from the front elevation. the plan view.

by projecting the

elevation

The method

view.

the

of

parts not already

to allow the nut to bear

fillet

drawn

upon a

flat

surface, will be

understood by fol.lowing the construction lines In drawing office practice this curve

5, 6.

by an arc of a

circle

made

to

3,

4,

drawn

usually

in inches.

undesirable to counterbore the piece upon which

it is

the nut bears, as is

is

2,

I,

passing through the limiting points.

All parts are dimensioned

When

in that

drawing the curve formed by cutting

in

Fig. 65, the cylindrical portion of the nut

into the collar C,

fit

Fig. 66, which

is

carried

upon the outer surface of the connected piece, and kept from The nut is secured by the rotating by means of the pin P. set-screw

bottom

5

passing through the collar and pressing on the

of the

of the nut.

In

some

is

cut upon the cylindrical part

P is

cases the pin

connected piece, but

in the it is

groove which

in

the example

screwed into the piece to avoid the

the nut and collar are removed.

The

are the same as in the last exercise. are

D=

+ Ty. which

fits

2d, c

The

=

28

length

= \d + of P =

into the collar.

fitted

|". 2

into the hole

shown

risk of losing

it

66

when

proportions of the nut

The

collar proportions

The diameter times

in Fig.

its

of

P=

\d

diameter, half of

SCREWS, NUTS, Exercise 20.

ment shown

Draw an

in Fig. 66.

AND

BOLTS.

99

elevation of the locking arrange-

Make

d=

Scale full size.

2".

x FIG. 66.

Circular Nut-locking Device.

arrangement shown

The nut and

its

locking

67 are used for securing the form shown in Fig. 67. On of the a cross-head piston-rod to the outer surface of the nut N, longitudinal grooves are cut, into which

screwing

it

in

Fig.

the projections on up,

fit.

The

the spanner,

locking-plate

for

employed

LP consists

of a plate

shaped to suit the curvature of the nut, and has a projection

which

fits

into one of the spanner grooves.

screwed into the surface upon which the

The stud 5

n'ut is carried,

ing through the groove in the locking-plate (LP) and

vented

from

unscrewing by making

the

part

is

pass-

is

pre-

within

the

IOO

\DRAWING AND DESIGNING. The method

luare.

>tud

S

is

of locking the nut

is

as

screwed into the metal at the proper

FIG. 67.

distance from the centre of the nut

A

7 ",

forming an angle with

the radial line which passes through the centre of the projec-

SCREWS, NUTS,

AND

on the locking-plate equal to between two of the spanner slots. tion

be locked

in

any

LP, with

position, the locking-plate

IOI

half the angular distance

This allows the nut to

N

After the nut

position.

one of the grooves,

HOLTS.

is

projection fitting into

its

passed over the stud until

is

screwed into

it

rests

upon

The nut can then be

the piece fastened by the nut N.

locked securely by clamping the locking-plate LP, by screwing

The nut

down N.

under side which

upon which nut

it

N has

into a corresponding recess in the piece

fits

This insures that the outside of the

bears.

concentric with the

is

a cylindrical projection on the

arc which

passes

through the

It also gives a greater

centre of the locking-plate.

length of

nut without increasing the distance which the nut projects

from the piece

The

it is

fastening.

proportions of the nut and

follows:

"-.

D= F=

locking device are as

its

f

diameter across the angles of the hexagon; diameter across the

the hexagon;

flats of

H=d+ i"; t

=

W= Make

.04^

+ .13.

the diameter d' of the stud

2" or under, and f"

for all nuts over

width of the groove eter of the stud

Exercise 21.

its

J" when nut

2"

diameter.

in

N

is

The

in the locking-plate equal to the diam-

+ TV'.

the stud =.d' and

5=

The width

length

Draw

a

=

/

fluted

of the square

body on

".

circular

nut and

locking

DRAWING AND DESIGNING.

102

arrangement, as shown

in Fig. 67.

Make d =

6".

Scale 8"

to the foot.

Locate the centre

Construction.

lines,

draw the

circle

F=

ij^+i"- Tangent to the circle making the diameter draw the line 2 to make an angle of 30 with the horizontal. Determine the radius r of the arc passing through the centre of

the

nut-lock

and complete the plan of the nut-lock.

Determine the centres of the spanner grooves by circumscribing on the half of the circle I, three sides of a hexagon, as in Fig, 67.

The

sides of the groove are parallel to the radial

which bisect the angles formed by the sides of the Projecting from the plan complete the elevation. hexagon. lines

Construction lines are not to be inked

in.

shown a nut-locking device used ing the piston-rod to the piston shown in Fig. 66. In Fig. 68

N in

is

this case

is

under side which

piston.

The

through is

cut.

this

into a corresponding recess in the lock-

fits

LP, which

The nut

and has a projection on the

of cast steel

ing-plate

for secur-

in turn

fits

into a circular recess

locking-plate has a tapped hole through

tapped

on the it,

and

hole, at right angles to its axis, the ring its

locking-plate has been screwed

P is

inserted into the tapped hole.

After the nut with

into place a tapered plug

This opens the saw-cut and forces the locking-plate against the sides of the circular recess on the piston.

The nut

is

thus securely locked by the friction caused by the pressure of the locking-plate against the sides of the recess. The following proportions plate

d

=

may be used

:

nominal diameter of screw;

F= distance across the

flats

J";

for the nut

and locking-

SCKEWS, NUTS,

AND

BOLTS.

103

DRAWING AND DESIGNING.

=

t

threads per inch

.09^/4-

The f"

size

of

;

H = d + thickness of locking-plate T

number

thickness of standard nut having the same

;

.7.

the pipe-tap

of

pipe-tap.

The

projection

is

=

on

\d, but need not exceed

under

the

side

of

the

=7"+ ^V to allow the nut to bear upon the piston. = W twice the diameter of the tapped hole at the small end.

nut '

Draw

Exercise 22. in Fig. 68,

d=

the nut-locking arrangement

shown

showing part of the piston and piston-rod.

Make

3" and having

5

To

Construction.

threads per inch.

hexagon turn to Table of a nut having

5

Scale full

size.

find the distance across the flats of the 8,

page 72, and

find the thickness

threads per inch by subtracting the radius

of the screw from half the distance across the flats.

To

find

the diameter of the tapped hole at the small end, turn to the table of Wrought-iron Pipes on page 57.

actual outside diameter

is

i" of

its

length.

number

size of the

the diameter of the tapped hole at

the large end, and the hole

dimensions

The

is

-fa" less in

diameter for every

Complete the drawing, substituting the

in inches for

the reference letters, and give the

of threads per inch

on the piston-rod screw and the

nominal diameter of the pipe-tap. Pins connect pieces by their Pin and Pin-joints. ance to shearing at one or two cross-sections. Split Pins, of a

when made

of a uniform diameter

resist-

from wire

semicircular cross-section and provided with a head,

used for preventing pieces from separating, while allowing a slight motion in the direction of

as

in

Fig.

69, are

the axis of the piece that they pass through, as

in

Fig. 67.

SCREWS, NUTS,

The method of drawing split The diameter of the pin, in

AND

pins

is

BOLTS.

clearly

105

shown

in Fig. 69.

proportion to the diameter

d of

D.R.

FIG. 69.

the piece

it

passes through,

nearest size in

Taper

may be

=

.05^+

.13, taking the

-fa".

Pins, shown in Fig. 70, are used for securing one

shown

in Fig. 71.

are sometimes split at the small end, and

opened out

piece to another in

a-

fixed position, as

FIG. 70.

They in

the same manner as the ordinary split pin, to prevent

slacking back.

The diameter

of the tapered pin at the large

end, in proportion to the diameter (d} of the piece through

which

it

passes,

may be made

nearest size from Table 10.

=

.o6^/+ .13 and taking the

io6

DRAWING AND DESIGNING. TABLE

10.

STANDARD STEEL TAPER-PINS. Taper one-quarter inch Number

to the foot.

SCREWS, NUTS, which

fits

The

into the fork.

and fork are either

left

AND

BOLTS.

107

parts of the rods near the tye

square or have the corners taken

for a distance,

which makes a part of the rod octagonal

cross-section.

In the arrangement

P

is

allowed

which

is

to

turn and

is

kept

secured to the turning-pin

shown

in Fig. 71,

off

in

the pin

in

place by the collar C,

P

by driving

a taper-pin

W

of the collar should through it and the collar. The width not be less than 2j times the diameter of the taper-pin.

Another method pin in place

shown

in

is

Fig.

in

common

to use a loose

washer

In Fig. 73,

72.

use for holding the turning-

(W) and

the pin

P

is

split pin, as

held against

FIG. 73.

turning by a taper-pin/ driven transversely through one of

arrangement

all

the eye of the rod bush.

R

and partly into the pin P. By this the wear, due to the turning motion, is on

the eyes on the rod

R' which t

is

fitted

with a steel or bronze

DRAWING AND DESIGNING.

IO8

The

Proportions given

in

joint stronger than the solid rod. for

Figs.

72

This

is

and 73 make the necessary to allow

bending stresses produced when the pin becomes worn.

Unit of proportions d. Exercise 23 Draw a PLAN, ELEVATION, and of the joint

shown

in Fig. 71,

END VIEW

showing the method of holding

the pin in place by means of a split pin and washer.

d

\"

Make

Scale full size.

Draw a PLAN partly in section, an ELEVATION and SECTIONAL END VIEW (the plane of section passing Exercise 24

through the rod Fig. 73.

Make

at the line ab) of the

d=

ij".

Scale full

knuckle joint shown in size.

CHAPTER KEYS, COTTERS,

Keys

are

employed

to

II.

AND

GIBS.

connect wheels, cranks, cams,

motion by rotation. They are generally made of wrought iron or steel, and are commonly The form of rectangular, square, or round in cross-section. etc,, to shafting transmitting

in

key

general use

is

made

slightly tapered

and

into the key-way, offering a fractional holding

the keyed piece moving along the shaft.

fits

accurately

power against

The groove

or part

where the key fits on the shaft, and the groove into which it fits on the piece it is holding is called the key-bed, key-

way

For square or rectangular keys, when the stationary on the shaft, the bottom of the

or key-seat.

keyed piece is groove on the shaft groove

is

in the piece

parallel to the axis, while that of the

it

is

securing

is

deeper at the one end

than the other to accommodate the taper of the key. Keys may be divided into three classes: I. Concave or saddle key;

2.

flat

Saddle Key. slightly tapered

in

sunk key. This form of key has key;

3.

thickness and

side to suit the shaft, as

power depends

entirely

shown

upon the

is

but

parallel sides,

is

concaved on the under

in Fig. 74.

As

the holding

frictional resistance,

the pressure of the key on the shaft, the saddle key

due to is

109

only

no

DRAWING AND DESIGNING.

adapted for securing pieces subjected to a light this

is

key

usually

used for securing a piece permanently, the taper

made

I

in

in

i

64

to allow the

saddle key in that

by

increased

easily loosened.

This form of key, Fig. 75,

Flat Key.

It

key to be more

is

FIG. 75-

FIG. 74-

shaft.

is

96, but when employed on a piece requir-

ing to be adjusted, such as an eccentric, the taper to

When

strain.

it

makes a

rests

on a

flat

differs

surface filed

but as

fairly efficient fastening,

resisting the turning of the shaft

under

it,

there

from the

upon the it

is

drives

a tend-

ency to burst the keyed-on piece.

TABLE

11.

DIMENSIONS OF SADDLE AND FLAT KEYS.

3

5

7/16

3/i6

Sunk Keys shaft

5/i6

7/16

5/i6

9/16

are so called because they are sunk into the

and the keyed-on piece, Fig. 76, which entirely preFor engine construction they are usually

vents slipping.

rectangular in cross-section and all

sides

When

made

to

fit

the key-seat on

subjected to strains suddenly applied, and

AND

KEYS, COTTERS,

Ill

GIBS.

DJt.

FIG. 76.

in

one direction,

they are

placed

to

drive

a

as

strut,

diagonally, as in Fig. 77.

FIG. 78.

FIG. 77-

The

from

following table, taken

Richards's

"

Machine

Construction," agrees approximately with average practice:

TABLE DIMENSIONS

D B T

OP'

RECTANGULAR SUNK KEYS.

2

5/i6 5/32 3/i6

7/16 9/32 5/i6

12.

3 5/8

7/i 6

4

112

DRAWING AND DESIGNING.

than breadth.

For machine

in cross-section.

used by

Wm.

The

Sellers

tools they are generally square

following table gives the sizes of keys

&

Co. both for shafting and machine

tools:

TABLE

13.

KEYS, COTTERS,

AND

GIBS.

1*3

J.

-L__j

1

~

_SHAFT

FIG. 79.

Sliding Feather Key.

FIG. So.

This system of keying secures

the piece to the shaft, to transmit motion of rotation, and at

the same time allows the keyed-on piece to

move along

the

DRAWING AND DESIGNING.

114

the work being thrown out of true by badly fitted keys, and, in

being deep

the shaft,

cannot turn

it

in

the key seat.

FIG. 820.

When

Key-heads.

the point of a key cannot be con-

veniently reached for the purpose of driving

formed on one end, as shown proportions and method '*

in Fig. 76,

it

keys on

flits

They

accuracy.

are

is

Which shows the RlCHARDS'S

to

(i)

to

as

when

fastening

general rule, however, conditions,

all

is

power transmitted and

power transmitted by the eccentrics,

etc.

the

amount

exceedingly great

breadth of key;

L=

length of key;

=

As

a

keys are proportioned to suit the

B=

2

crushing

crank-shaft couplings,

in

of

power

trans-

comparison with

that taken off at the keyed-on piece.

Let

keys

transmit the whole of the

pulleys,

unless where

mitted by the shaft

"the

shearing

shaft, as in

or (2) only a part of the

shaft,

first

where

subjected

power transmitted by the etc.,

of saddle

small.

and are required

strain?,

is

cannot be calculated with any degree of are used only

by the keyed on piece

Sunk Keys

head

of construction given in

MACHINE CONSTRUCTION." Strength of Keys. The driving power

or

out, a

radius at which key offers a resistance;

AND

KEYS, COTTERS,

a

.igod /s

=

11$

the material which

the shearing of

iron

for

GIBS.

wrought modulus of the

and

1

section

is

=

9000

1,000 for steel. of

shaft

for

torsion

\j2od* for wrought-iron and 2i82*/

3

for

steel shafts;

R=

the radius of arm through which P, the power, is

Under the

transmitted.

conditions the strength of a tight key

first

would be found by the formula

......

(16)

and under the second conditions by the formula

f.BL^=PR ........

(17)

In the system of sliding keys the crushing action on the

key is greater than when the key is a tight fit in the key- way, and keys of this type should be proportioned to have the

moment moment

of shaft

of

torsion

key crushing.

=

the

moment

of

key shearing

Then

-,

and

B

if

is

we take fe

=

2/

s

,

=

T=

then

B.

.

.

.

(18)

In practice, however,

generally greater than T.

Length

of Key.

From

the foregoing formulae

seen that the strength of the key (L) the length.

To

is

find the length

it

will

be

directly proportional to

L when

the

full

power

of

DRAWING AND DESIGNING.

Il6 the

shaft

formula No.

From

be transmitted through the key.

to

is 1

noooBL- =

2i82<2",

-

,

5500

substituting the value of

B

from Table 12

2182^

L=

5500

Hence when the the

be

length less

>

X

=

in

I

.

terms of

oa.

.

shaft and the key are of the

(L) of

the

common key

When

than i.6d.

d

same

material,

(Table 12) should not

the hub of the keyed-on piece

so short that one key has not sufficient strength, two or

keys are used.

Where two keys

is

more

are used they should be

placed at right angles to each other.

arrangement the held upon three points, which prevents it

By

this

keyed-on piece is from rocking upon the shaft when the shaft in

is

not a tight

fit

the hole.

are keys

to tensile

employed to connect pieces which are subjected and compressive forces. They are driven trans-

versely through one or both of

transmit sections.

section,

power by

The

a resistance

cotters are usually

and the ends rounded,

The cotter-way adopted, as

it is

with

easier to

as

the connected pieces and to shearing at

made shown

two

cross-

rectangular in crossin Fig. 83.

rounding ends is generally make, which is done by drilling two the

KEYS, COTTEXS,

AND

GIBS.

1

1/

holes of a diameter equal to the thickness of the cotter and

cutting out the metal between them.

Again, this form of

cotter-way does not weaken the cottered pieces to quite the same extent as when the corners are left sharp. The cotters,

however, are not so easily

cotter-ways with round

fitted into

some engineers make the

ends, and for that reason

rectangular cross-section,

into

fitted

cotters of

corresponding cotter*

ways.

FIG. 83.

Taper means

of Cotters.

When

cotters

are

employed as

a

of adjusting the length of the connected pieces, or for

drawing them together, they are made tapered in Fig. 83,

width, as

but when used as a holding-piece only, the sides

are parallel, as in Fig.

upon the

in

friction

56.

between

When

tapered cotters depend

their bearing-surfaces for retaining

DRAWING AND DESIGNING.

Il8

them

P er

(i"

more than

position the taper should not be

in

holding the cotter against slacking, the taper as great as I in 6 (2" per foot).

Forms and Proportions fastening

is

subjected

shown

in Fig.

means

of a cotter.

rods,

R

joint

is

and

in

24

but where special means are employed for

ot )'

f

I

84

R

',

made by

is

to

may be made

of Cotter-joints.

tension

the

only,

When

the

arrangement

used for securing two pieces together by Fig. 83

shows a method

of fastening

together to resist thrust and tension. fitting

the end of the rod

R

two

The

into a socket

^

formed on the end of the rod R', and through the socket and rod end driving a cotter until the collar C bears against the socket end.

As

a cotter-joint

is

proportioned to withstand the greatest

longitudinal force transmitted by the rod,

all

parts will there-

fore be proportional to the diameter d^ of the rod, unless

where the dimensions ness.

The

of the rod are increased to insure

stiff-

following proportions are in accordance with good

practice:

= 1.3^,; thickness of cotter = .3^; ^d, diameter of pierced rod = b

t

breadth of cotter

t,

D, diameter

1.2^;

=

of socket in front of cotter

/},

,

diameter of socket behind cotter

Z> 3

,

diameter of collar on rod

=

R = i.5<^, R J^;

2.4^ or

2^.

2^,; ;

t,

thickness of collar on rod

/,

the length of the rod and socket beyond the cotter

=

from

KEYS, COTTERS,

When d The

is

known

AND

GIBS.

the diameter of the solid rod (d^

clearance c

may be made

The

".

cotter

=

need

not extend beyond the greatest diameter of the socket more than

"

when driven home. shows an arrangement often used

Fig. 84

engine piston-rod to the piston. collar 'on

the rod

R

to

resist

for securing

an

Here, instead of having a the thrust, the rod-end is

tapered.

FIG. 85.

FIG. 84.

In Fig. 85, the pierced part of the rod has a smaller

Such a condition

diameter than the solid rod.

when its

the diameter of the rod

having

is

is

possible

increased in consequence of

The

to resist buckling stresses.

joint being sub-

jected only to tension and compression, the rod would under

these conditions be excessively strong

diameter of the solid

rod.

We

if

proportioned to the

must therefore

the

find

(d,) and proportion the joint independently of the actual rod diameter, d, is found by the formula

diameter

(19)

from which

d. =: ~

-

V

Where

P

is

/

-

the pull on the rod.

j ~tj

i

.

For

steel

taken at 7000 and -5000 for wrought iron.

rods/,

The

may

be

taper of the

DRAWING AND DESIGNING.

I2O

may be made from J" to i" per foot of length, in 24. The diameter d on the tapered in 12 to

rod-end

from

end

I

I

when

taken,

is

the cotter-way

where the curve begins, cotter-way when

the cotter-way

Draw

is

curved

is

as in Fig. 84,

and

i.e.,

rod-

the end,

at

end of the

at the

rectangular.

SECTIONAL ELEVATION, a HALF HALF and SECTIONAL PLAN of the cotter-joint shown PLAN, Exercise

25

a

Make ^=2".

in Fig. 83.

Scale full size.

Exercise 26.

Design cotter-joints suitable for fastening a steel piston-rod to the piston and cross-head, as shown in Make the diameter of the rod d9 = 2f" and Figs. 84 and 85.

assume that the rod

is

subjected to a load of 9000

rod-ends having a taper of

I

The

Ibs.

Scale full size.

in 12.

Construction. Having determined the diameter (d) of a rod suitable for resisting tensile stresses, then from ^find the

other proportions of the joints, as the distances

off

/

in

Measure

Exercise 25.

and b along the centre

line

and mark

off

the

diameter (d) at the proper point according to the shape of the cotter in cross-section, then in the manner given in the construction in connection with

end the

to

the

taper

filling

given

taper.

Exercise

The

need not be inked

13

construction

in.

for

finding

Complete the drawing,

the actual dimensions and leaving

in

draw the rod-

off all

reference

letters.

COTTER AND

When a

thin

one of the

strap,

as

in

pieces Fig.

GIB.

connected

86,

a

second

by the cotter cotter,

called

is

a

is used. The gib is provided with a head at the ends which project over the strap S, thus preventing it

gib,

KEYS, COTTERS,

AND

(tne strap) from being forced open

and the cotter

and 89 show

as the latter

by the

friction

between

it

Figs. 86

driven into place.

the application of gib and cotter to strap-end

connecting-rods, where

two gibs

is

121

GIBS.

R

is

the rod and

5

the strap.

When

are used, as in Fig. 88, the sliding surface on each

side of the cotter

Instead of having both gibs one of them may be parallel Fig. 88, on one side of the cotter. The strength of is

shown

tapered, as

and the taper all the gib and cotter

the same.

in

in

combination

FIG. 86.

is

made

FIG. 87.

the same as the

FIG. 88.

and should be proportional to the strap S. The working strength of the strap at the thinnest part is found by

single cotter

the equation

from which

where

P is

(20)

the

maximum

pull

on the

re-*,

T the

thickness,

DRAWING AND DESIGNING.

122

and

B

are to have the is

t

Then

the breadth of the strap.

equal to, or a

may be made

same strength little

as the single cotter,

greater than

d

and as

B

(the diameter of the rod).

equal to ,2$B and

T', the thickness of the strap

should not be less than to the end of the cotter to the end of

not be less than

and cottrr

as the gib

c'

where

it is

the distance from the gib

/',

1.32".

pierced by the cotter,

= 2 T. strap, the rod, = 1.5 T.

/,

the distance from the c,

the clearance, should

between the widest part of

(the difference

the cotter and the width of the cotter at the top of the gibhead).

The method

Fig. 87,

where h the height

of constructing gib-heads

y

of the gib-head,

A

Cotter-locking Arrangements.

one that

is

used

in

all

nearly

cases,

=

is i

shown

in

\t.

simple method, and where possible, is to

screw one or two set-screws through the rod until the point

To keep

or points press against the cotter.

the burs, raised

by the point of the screw, from

interfering with the motion

of the cotter, the set-screw bears

on the bottom of a shallow

groove cut on the side of the cotter, as shown in Fig= 89. The diameter of the set-screw need not exceed f". The length of the groove

is

equal to the travel of the

+ the diameter of the set-screw.

The

cotter

travel of the cotter

the distance from the top of the gib (or where no gib

is

is

used

r

from the top of the piece into which the cotter passes) to the top of the cotter when the cotter

The width

of the groove

j

s

set-screw point, and the depth

just in place.

is

equal to the diameter of the

=

1

T ^-".

KEYS, COTTERS, In Fig. 90 the cotter

is

AND

GIBS.

123

locked by an upper and lower nut

upon a screwed extension of the gib, which passes through a head formed on the cotter. This arrangement is used for fastening

in,

and may be used

for forcing the cotter into,

oosition. d, the /z,

As

diameter of the screw

the height of the head

the axis of the locking-screw

side of the cotter that

is

in

is

=

=

/;

\\d.

not parallel with the

contact with the gib, the hole in

the cotter head through which the screw passes

is

elongated

D.B.

u FIG.

to an amount equal to the taper of the cotter travel

1

-f-

T ^"

/

FIG. go.

length of

in its

for clearance.

Exercise 27

Draw

a

SECTIONAL ELEVATION and

SECTIONAL PLAN, a PLAN, and SECTIONAL END VIEW and

cotter- joint to resist a tension of 12,000 Ibs.

diameter (d) of the rod

=

2".

The

a of

HALF n

Make

gib-

the

cotter to have an adjust-

DRAWING AND DESIGNING.

124

ment

of

\" with a taper

=

i

in

8.

Show

locking the cotter by means of a set-screw.

Draw

Exercise 28. of a double gib-

a

proportioned to

resist

have an adjustment diameter of the rod

of

SECTIONAL ELEVATION AND PLAN

shown

in

Fig. 90.

in Fig. 88,

The

with

joint to

be

a tension of 33,000 Ibs., the cotter to

of

=

method

Scale full size.

and cotter-joint as shown

the locking arrangement

the

f" and a taper of

3''

'.

Scale full size.

I

in 10.

Take the

CHAPTER

III.

RIVETS AND RIVETED JOINTS. RIVETS

are

made from round

bars of steel, wrought iron,

copper, or brass, and are used to fasten two or

permanently together. The plates to be riveted are either

drilled or

more

plates

punched with

holes TV' larger in diameter than that of the rivet-shank.

When

the rivet

placed in position through the plates

is

a sufficient length of shank projects beyond the plates to pro-

vide for forming the rivet-point head either by

by machine-pressure

(see

Fig. 92).

Unwin

hammering calls

or

a riveted

" simplest permanent fastening." joint the Rivets are

made by being

pressed into shape while red-hot

with rivet-making machines using dies of suitable size and form.

The names and 92 to

96

will

The end up

is

proportions of rivet-heads shown by Figs.

be given

later.

of the rivet opposite to the

called the point

head before riveting

and after riveting the point-head. is heated red-hot and when

Just before using the rivet

placed in position for hand-riveting a large

hammer

is

held there by means of

with a long handle fulcrumed at a convenient

distance from the rivet and a man's weight applied at the end,

made by two riveters either in the form head by hammers only or the snap head (Fig.

while the point-head of the steeple

92)

by using

is

a cup-shaped die called a snap. 125

DRAWING AND DESIGNING.

126

In machine-riveting the point-head

by

suitable dies, the motive

hydraulic,

or

the rivet and

the hole

either a lever, steam,

power being

pneumatic pressure. fills

much

pressed into shape

is

Machine-riveting upsets

better than hand-riveting, be-

cause the steady even pressure of the former

formly through the whole of the is

Hydraulic riveting

is

exerted uni-

rivet.

preferred to steam-riveting, because

the pressure from the former can be gradually applied, while the force from the latter generally comes upon the rivet with

such rapid blows that sufficient time rivet to properly

Rivet-holes

fill

is

not allowed for the

the hole.

punched through

rigid

steel

plates should

always be annealed after punching, because the punching injures the material surrounding the hole to such a dangerous extent that the elasticity of the plate

destroyed, and

is

subjected to strain the stress

the joint

is

tributed

between the

punched holes

is

is

not uniformly dis-

Another

rivet-holes.

difficulty

with

the imperfect spacing of the rivet-holes.

Drilled holes are usually

more expensive than punched

holes and the sharp square edge

is

not as favorable to the re-

sistance of the rivet to shearing, but they are size

when

and spacing, and

more accurate

in

the resistance of the rivet to shearing

can be increased by slightly rounding the edges of the holes.

Calking.

No

This

without calking. of

the

is

is

ever perfectly steam-tight

a process by which a narrow strip

bevelled edge of one plate

contact with

At

riveted joint

he plate beneath

#, Fig. 91, is

in hand-calking,

patented bv Mr.

and J.

is

brought into forcible

it.

shown the calking-tool commonly used at b

an improved form of calking-tool

W. Connery

of Philadelphia

and known as

RIVETS AND RIVETED JOINTS.

127

the concave calking-tool from the concave finish -aven to the

This

calked edge oT the plate.

is

a favorite style of calking

with locomotive-builders for high-pressure boilers.

FIG. 91.

Calking

with

quite general in

pneumatic calking-hammers has become most first-class boiler-shops. Peabody and

Miller in their " Steam-boilers" describe a pneumatic caik-

ing-machine as follows:

" In general

principle

it

resembles a rock-drill and consists

of a cylinder in which works a piston and rod on the end. of

DRAWING AND

128

which

is

Air

the calking-tool.

supplied for working the

is

piston at a pressure of 50 or 60 Ibs. through a flexible tube. It

makes about 1500 working strokes a minute T3/'

calker which

over

seam

all, is

is

about 2^"

held by a

in

The edges show a

it

presses

of the tool

as not to injure the lower plate. as rapidly with the

The

diameter outside and 15" long

workman who

The edge

to be calked.

long.

Work

is

slowly along the well rounded, so

can be done four times

pneumatic calker as by hand."

when they some of the

of rivet-heads are not calked except

leak during the process of testing.

largest boiler-shops an inspector

when

In

employed part

is

of

whose

examining a boiler to discover

if any of the done by placing a finger on the under side of the suspected rivet and tapping the top of it with a

duty

it

is

rivets are loose.

small

This

hammer made

is

for the

purpose

;

if

the rivet

is

not per-

be easily detected by the finger; in such a fectly tight case the loose rivet is cut out and replaced by a new one. it

will

The Forms

of Rivets.

in general use are:

(i)

The

the button

T"

FIG. 92.

standard

forms of rivets

head (Fig. 92);

(2)

the

RIVETS AND RIVETED JOINTS.

I2 o

conical head (Fig.

93); (3) the steeple head (b) (Fig. 94); the head (4) steeple (d) (Fig. 95) (5) the countersunk head ;

(Fig. 96).

The head,

is

The

button head, or, as usually

made with

conical'^ also a

it is

sometimes named, the snap

a machine-riveter.

machine-formed head and

used' with a button point-head or tail

steeple point.

FIG. 94.

is

commonly

and sometimes with a

DRAWING AND DESIGNING.

130

The

steeple

point-head

is

the form mostly used in hand-

riveting.

The

countersunk point-head

sufficient

room

used unless

it

for is

is

only used

there

is

not

one of the other forms and should never be

impossible to avoid

than, and not as strong

as,

It

it.

is

more

costly

the other forms.

FIG. 96.

FIG. 95.

the

when

Proportions of Rivet-heads. The proportions given in figures in terms of the diameter d are those used by

Champion Rivet Co. and agree

the

closely

with general

practice.

Length

The

length

and

of Rivet-shank.

L

(Fig. 92) for countersunk point-head

id

2 plates.

For countersunk point-head and 3 plates For steeple point-head For steeple point-head, large, machine-driven For button point-head The above proportions are good for ordinary but, since the holes are

^"

larger than the

id +i"

boiler-plates,

rivet,

the shank

RIVETS AND RIVETED JOINTS.

l^l

should be increased in length for thick plates to properly the additional annular space.

The

rivet-shank

is

usually about

^"

fill

smaller in diameter

than the hole and has a slight taper toward the point. Make a drawing of each style of riveting Exercise 29.

shown

in

Figs, 92 to 96,

from Table

14,

/

making

" equal to f and selecting

page 135, the diameter

ventions see page 22.

There are

Riveted Joints.

97);

(Fig.

spacing (Fig. spacing

rivet.

common

in

different styles of riveted joints, viz.

joint

of

For con-

Scale full size.

:

use at least five

the single-riveted lap-

the double-riveted lap-joint with staggered

98)

;

(Fig. 99)

;

the double-riveted lap-joint with

chain

the single-riveted butt-joint with

chain

spacing (Fig. 100); the double-riveted butt-joint; the multiple-riveted lap-joint in

the lap

;

which has more than two rows

of rivets

the multiple-riveted butt-joint which has

more

than two rows of rivets on each side of the line where the plates butt together (Fig. 103).

NOTATION.

d

=

the diameter of the rivet-hole or of rivet

/

=

the pitch of the rivets,

when

riveted

up.

tre of

row

one

i.e.,

the distance from the cen-

rivet to the centre of the

next in the same

(Fig. 97).

the distance from the centre of rivet-hole to edge of

/

plate (Fig. 97).

r fi

= =

the distance between the rows on double-riveted joints. the distance between joints with welt-strip

outside rows of rivets

and

butt-joints.

on lap-

DRAWING AND DESIGNING.

132

m=

the least distance between the edge of rivet-hole and

edge of plate

= = = = = ft f =

=

margin

(Figs.

97 to

103).

the thickness of plate.

i

/i

thickness of outside welt-strips for butt-joint.

/,

thickness of inside welt-strips for butt-joint.

/'

thickness of inside welt-strips for lap-joint.

the tensile strength per square inch of the plate in Ibs.

the shearing strength per square inch of the rivet in

f

Ibs.

=

the shearing strength per square inch of the plate in

f =

the compressive or crushing strength per square inch of

ft

Ibs. c

the plate in '/?

=

Ibs.

the radius of boiler in inches on the outside of course of smallest diameter.

= K= P=

the width of narrowest welt-strip.

./>

outside diameter of boiler-shell

the width of widest welt-strip.

ft

working pressure

in Ibs.

per square inch. at course of smallest

diameter.

F= E= T= a =

factor of safety. efficiency of riveted joint. total tensile stress.

area of rivet-hole

=

.7854^*.

There are five differStrength of Single-riveted Joint in a which ent ways single-riveted lap-joint may give way :

(1) Shearing the rivet, as (2)

shown

at

Tearing plate along the centre

I

in Fig. 91.

line of rivets,

shown

2, 2. (3)

Tearing the plate through the margin, shown at

3.

at

RIVETS AND RIVETED JOINTS. rivet or the plate in front of the rivet

Crushing the

(4) (4, 4).

Shearing the plate

(5)

The

in front of the rivet (5, 5).

shearing strength of the rivet

nd*

= The

X

X/,=

4

resistance of plate to tearing

.ft

The

resistance

made

practice,

the

it

will

enough when

3

(2)

has been

the distance

this

resistance of the plate at

X d X fe

work.

4

is

......

.

(3)

resistance to shearing the plate in front of the rivet

as shown at

5,

5.

= if

the joint

is

2t

made

X

/

.....

X //

.

(4)

strong enough to resist shearing

the rivet or tearing the margin resist

line of rivet

.......

be maintained throughout

t

But

(i)

equal to i^d, and, as this rule agrees with general

The compressive

The

on centre

plate to tearing at

experiment to be great

found by /is

of

...

38,000.

it

will

be strong enough to

shearing or crushing the plate in front of the rivet, so

that the latter

The

may

generally be disregarded.

thickness of the boiler-plate

PX XX F The

value for

/

teenths of an inch.

is

PR

should be taken as the nearest even six-

Take

E=

.70.

DRAWING AND DESIGNING.

134

The

thickness of

may be

dome-sheet

calculated

by the

same formula. In locomotive-boilers the thickness of tube-sheets for f" shells

and over should be \" to

When

shells are less

than f

-jV'.

"

thick

thickness of tube-sheets equal to

The

throat-sheet

is

/ -f-

make the

\

n '.

made

usually

usual to

it is

thicker than

-J-"

the

shell to allow for extra flanging.

V

In thick shells, f" or over, T

When

the back tube-sheet

separated from the fire-box

is

made

throat-sheet the latter should be

the fire-box side sheets,

The

viz.,

fire-box crown-sheet

and door sheets

thicker will be sufficient.

the same thickness as

5

y /'is

usually

made " and

the side

$" thick.

Diameter d of Rivet-hole. ing riveted joints to obtain

It is

very desirable in design-

the highest efficiency and

still

maintain a proper tightness by using a pitch not too long for calking.

In determining the diameter that

it

d

of the rivet

should be strong enough to

crushing.

Now

the resistance to shearing

while that of crushing

necessary

is

,

latter increases as the

former as the square of the diameter. tain such a relation

is

is

dtfc

which shows that the

it

both shearing and

resist

diameter and the

So that

if

we can ob-

between the length of the pitch and the

RIVETS AND RIVETED JOINTS. diameter of the rivet-hole as

135

will give the highest efficiency

consistent with tightness the crushing strength of the rivet

or the plate in front of the rivet need not be considered.

To

our knowledge the

maximum

limit for the length of

pitch that will insure perfect tightness of the joint has never

been ascertained by experiment or

test, so that

we have

depend largely on existing practice in determining the between d and /. Mr. Wm. M. Barr in his " Boilers and Furnaces"

to

ratio

gives

the following ratios between the thickness of the plate and the diameter of the rivet for single-riveted lap-joints, using

the nearest even sixteenths of an inch, for steel plates and steel rivets (tensile strength of plates

strength of rivets 44,625

Ibs.

55,000

Ibs.

per square inch):

TABLE

14.

and shearing

1

DRAWING AND DESIGNING.

36

TABLE t

15.

RIVETS AND RIVETED JOINTS. Determine diameter d of

(2)

rivet

137

from the mean

ratio

in Table 15.

Calculate the pitch/ by formula 6, page 136.

(3)

===i Section at SS. FIG. 97.

Make complete drawings tual dimensions

as

Single-riveted lap-joints are ential

shown

in Fig. 97, giving ac-

in place of letters.

commonly used

for circumfer-

seams of steam-boilers.

To

determine whether a circumferential seam should be

single- or double-riveted let us take the following

example

:

Diameter of boiler 48". Steam-pressure per square inch 148

Diameter of Pitch

^ 2".

Thickness of plate

The

=

total force will

.7854>

The

Ibs.

rivet = .875".

a

P=

resistance

.375".

be

1809.6

due to the

X

148

= 267,820.8

Ibs.

.

(7)

rivets

^.

(8)

DRAWING AND DESIGNING.

138

n

= the

number

of rivets in the circumferential seam.

F= the factor of safety = 6. Therefore, substituting,

we have

= 285,475 and, subtracting the force from the resistance,

we have

a dif-

ference of 17,654.2 Ibs. in favor of the rivets.

The d)

(/>

total resistance of the plate

X

*

Xft X

F

n

_

1.125

X

is

.375

X

'

55>QQQ

X

75

= 288,750

x

(9>

6 Ibs.,

and, subtracting the total force, 267,820 there remains a difference of 20,929

Ibs.,

Ibs. in

from 288,750,

favor of the plate,

which shows that a single-riveted lap-joint is strong enough for the circumferential seams of a boiler of the above dimensions.

Prof. his ""

"

Lanza

referring to the efficiency of riveted joints in

Applied Mechanics" says:

A

riveted joint of

maximum

efficiency should fracture

the plate along the line of rivets, for

it

is

clear that

if

failure

occurs in any other manner, as by shearing the rivets or tear-

ing out the rivet-holes, there remains an excess of strength

along the line of riveting, section of plate

if

in a

or, in

other words, along the net

single-riveted joint

which has not

been made use of; but when fracture occurs along the net section an excess of strength in other directions is immaterial.

RIVETS AND RIVETED JOINTS. "

If the. strength

constant

139

per unit of metal of the net section

is

would be a very simple matter to compute the of any joint, as it would be merely the ratio of the

it

efficiency

net to the gross areas of the plate.

" The tenacity of the net section, however, varies and variation extends over wide limits." This being longer than

is

so,

the pitch in the last example

98

The

riveting.

slightly

necessary.

Double-riveted Lap-joints rivets in Fig.

is

this

is

The arrangement and

called chain riveting

double-riveted

is

joint

in

of

the

Fig. 99 zigzag

than

stronger

the

single-riveted joint because of the greater net section of plate

and smaller diameter of in steam-boilers

plates and iron

All longitudinal seams

rivet-holes.

should be

at

double-riveted.

least

Steel

rivets are considered the safer practice because

of the danger of overheating the steel rivets.

Wm.

M. Barr

in his

" Boilers and Furnaces" referring to

the heating of steel rivets says: "It rivets be uniformly heated

merely, as

is

the ordinary

important that steel

is

throughout, and not the points

method

of heating iron rivets;

neither should they be heated as highly as iron rivets, and

should never exceed a bright cherry-red. should be given to the thickness of the

" if

If

excluded from free oxygen steel cannot be burned; is high enough it can be melted but burn-

the temperature

ing

is

Particular attention

fire.

impossible in a thick fire

;

with moderate draft."

Chain riveting with rivets of the same pitch has been found by experiment to be stronger than the zigzag riveting. See Barr's " Boilers and Furnaces," page 85, where it states that the lap

is

wider for chain riveting,

"and no doubt

the

fric-

DRAWING AND DESIGNING.

140

tion of this wider joint contributes towards the observed in-

crease in strength," but the late D. L. Barnes and others

have tested riveted joints state that the plates

friction

who

between the

cannot be considered, because long before the

ulti-

mate strength of the lap is reached the plates are so far apart that " you can stick a knife-blade between them." The zigzag riveting

is

preferred in locomotive-boiler seams, because

the joints are tighter under the high pressures carried than

they would be with the wider lap of the chain riveting.

25'

Section atSS. FIG. 98.

Exercise 31.

Make

the drawings for a double-riveted lap-

joint, chain riveting, like Fig. 98,

except that the actual

di-

mensions should be given instead of the letters shown. Steel Thickness of plate = -|", / = 3 T5^ plates and iron rivets. Scale 6" = i ft, if, t= \%d, r' = 2d+ I", R = 30". '

',

d=

Calking need not be shown now. Calculate the efficiency of this joint in comparison with the strength of the plate.

RIVETS AND RIVETED JOINTS. at

Taking/,

55,000

strength of solid plate

/X The

t

Xft

shearing

(for 2

net is

at

38,000 as before, the total

is

3-3 I2 5

X

.625

X 55,000=

strength of the net section of plate

(/-<*)(//

The

=

and/

=(3-3125-

rivets)

section" of

1.

125). 625

strength of the rivets

=

141

110,000

Ibs.

is

X .

55.000

=

75,735.

7854^' X 38,000

X2

75,544, nearly equal to the strength of the

the plate.

Therefore the efficiency of the joint

equal to

E= The

75,544 110,000

= 69

following ratios of

d

per cent nearly.

to

/

for double-riveted joints

were calculated from the report of a committee on riveted joints to the

Am. Ry. M. M.

Association in 1895

TABLE /

16.

:

DRAWING AND DESIGNING.

142

Prof.

Kennedy

for the diagonal pitch,

gives

r

may

be found graphically or calculated by formula T

r"~-

Table 17 gives the distances (r) calculated by

formula

this

for the different sizes of rivets.

Make drawings

Exercise 32

as per Fig.

riveted lap-joint, zigzag riveting.

t

=

99 of a double-

", ratio of

d to

t

=

Sectioa at SS. FIG. 99. 1. 80,

R=

30".

/

=

Find r by formula Exercise 33.

\\d

in

II.

^cale 6"

even TV".

Find/ by formula

Make drawings

i foot.

10.

similar to those in Fig. 100

showing the junction of a double zigzag-riveted longitudina' seam with a single-riveted circumferential seam for a steamboiler,

/

t

= TV'> d calculated

from the mean

ratio in

Table

to be determined from formula 10, /' from Table 14,

29", r

may be

calculated from formula

1

1.

Scale 6"

~

16,

R=

i foot.

Actual dimensions to be placed on drawing where letters

RIVETS AND RIVETED JOINTS. show

in

Steel plates and iron rivets.

figure.

143

Finish sheet

according to directions given on pages 19 and 20. Lap-joints with Inside Welt-strip. This style of riveting,

shown

in

Fig. 101,

is

used for both single- and double-

Section a/SS i'IG.

riveting and possesses

of the features of the butt-

ana

In the single-riveted joint of this kind the middle

lap-joint.

row

some

IOO.

of rivets

which

rivet the three thicknesses of plate should

be spaced according to the

rule

given for

p

in

the single-

riveted lap-joints on page 136 and the spacing of the outer

rows

=

2/>.

These

joints are better than the simple lap-joint, but are

Uiore expensive, and are not

{Fig. 102),

which

is

any better than the butt-joint and less expensive. simpler

DRA WING AND DESIGNING.

144

The may

double-riveted lap-joint with inside welt (Fig. 101)

any one

fail in

(1)

By

of the following

By

:

shearing the rivets holding plate

Resistance against shearing (2)

ways

=

^a

X

(a).

Sa

f,

X

38,000.

(12)

tearing plate (a) along the outside row of rivets.

Resistance against tearing plate as above

= (3)

By

(2/

-

d)t

Xf =

(2p

t

-

a)t

X

55,000.

.

(13)

.

tearing plate (a) along the intermediate row

-f-

the

shearing of one rivet.

Resistance

=

(2p

2a)t

Strength of solid plate

=

X

55,ooo.

2p

X

t

.

Xf

t

.

(14) (16)

-

least resistance

~

*

strength of solid plate Exercise 34. lap-joint

with

Make complete drawings inside welt,

sectional view of this figure tion.

of a double-riveted

zigzag spacing, is

Fig. 101.

The

wrongly projected with inten-

Student must make correct projection.

Take the remaining dimensions from the following

TABLE

17.

DOUBLE-RIVETED LAP-JOINTS WITH INSIDE WELTS. <

-*

table

:

RIVETS AND RI VEILED JOINTS.

145

tudinal seams of steam-boilers with plates f" thick and over.

As shown by

Fig. 102, the boiler-shell

rolled to a perfect

is

cylinder and the two edges of the plate which butt together

FIG. 101.

are held

by two

welt-strips riveted 'to each other

and to the

ends of the plate.

=

In a repeating section of the plate rivets in

double shear and two half rivets

From experiments made by others is

it

has been demonstrated that

this to

in single shear.

the English Admiralty and

equal to 2 rivets in single shear.

assume

2p there are two

I

rivet in

double shear

For convenience we

be so at present, although

it is

will

quite usual for

designers of steam-boilers to use a value of from

1.

75 to 1.90

DRAWING AND DESIGNING,

146

for rivets in double shear; and, as the latter values agree

nearly with general practice for butt-joints,

it

will

more

be neces-

sary for us to modify our proportions in this regard, as will

appear later. Therefore to prevent the plate a pulling out from between the welt-strips the resistance to shearing will be

X

5

X /,

a

,

there being two rivets in double shear and two half rivets in single shear

=

areas in single shear.

5

Resistance to tearing the net section of plate at the outer

row

is

(2p-d)tf

t

.

Resistance to tearing the plate between the inner row of rivets

and shearing

rivets in outer

(2/

-

X

2.
row

/<

+

is

i*/,.

Resistance to crushing the plate in front of 3 rivets

fe

may be

taken

and 90,000

at

for steel rivets.

Strength of whole plate equal

2/

Draw

Exercise 35. riveted

102, given If

we

=

9

T T ",

X

/

elevation

butt-joint with /

per square inch for iron

Ibs.

80,000

is

d=

in

width to 2p

is

Xf

t .

and

cross-section of a double-

outer and inner welts similar to Fig. i.g2t.

consider the resistance to tearing equal to the

resist-

ance to shearing, then

iii

v= -^jf -'+* s

i

('*>

but this makes the pitch too long, because of the excess of strength in the rivets against shearing.

A

better proportion

RIVETS AND RIVETED JOINTS. and one that conforms to good practice

.85(909

2/=/,

and

/a

are usually equal to

'47

is

d.

tf but occasionally

/,

tl

will

be

FIG. 102.

The Hartford Steam-boiler Infound TV' thicker than t. spection & Insurance Company give all welt-strips ^" less in thickness

than

/.

For the remaining dimensions see the following table

TABLE

18.

For double-riveted butt-joints with outer and inner welt-strips.

t

:

DRA WING AND DESIGNING.

148

Triple-riveted Butt-joint with Outer and inner WeltThis joint has three rows of rivets on each Strips (Fig. 103). of the butt. One row passes through the boiler-plate and two rows pass through the sheet and one and welt-strip

side

two

welts.

The

resistance to tearing along line

-

d)tf

xx

is

09)

t

FIG. 103.

The

resistance to pulling the plate out from

welt-strips

is

9X

a

X/, X

.85.

between the

K1VETS AND A/FETED JOINTS. The on xx is

resistance to tearing

on

line

149

yy and shearing

rivets

A

glance at the figure will show that this joint cannot fail along the line zz, because there are two rivets in double shear and one rivet in single shear in addition to the net section of

which

plate,

is

equal to the net section on yy.

Exercise 36.

Make

joint like

Fig. 103.

d=

Scale

ij".

4!'

the drawings for a triple-riveted butt-

Steel plates and iron rivets.

=

The

I foot.

taken from the following table

:

TABLE t

19.

other dimensions

/

=

may

-|",

be

DRA WING AND DESIGNING.

150

Draw

Exercise 37. riveted

with a single-riveted circumferential lap-

butt-joint

/

joint (Fig. 104).

sions

may be

the junction of a longitudinal double-

=

f",

d=

\y

.

taken from Tables 18 and

The remaining dimen14.

Scale 6"

=

I foot.

FIG. 104.

Make drawings

Exercise 38.

of the staying for the back-

head and fire-box crown-sheet of a locomotive-boiler as shown

by Fig.

Scale

'

105.

3"

=

i foot. v"

This

is

an example of what

staying for locomotive-boilers.

engine with cylinders 19" square inch, and

is

X

is known as The design is

the croivn-bar suitable for an

24", steam-pressure 180 Ibs. per

similar to that used in the

Empire State Ex-

press locomotive designed by Wm. Buchannan, Supt. of Motive A A shows a cross-section Power of the N. Y. C. R. R.

and a

partial elevation of

one crown-bar which consists of two-

RIVETS AND RIVETED JOINTS.

\^\

X

f" thick and welded together " The fire-box crown-sheet is supported by at the ends. b and between the rivets, which, passing through a washer

wrought-iron plates 5" deep

plates

A

and through thimble G, is riveted on the the crown-sheet as shown. These rivets are placed

of the bar

under side of

from 4" to 4^" apart, and as many as the crown-bars will accommodate at these centres, the end bolts being placed about As seen from 4" from the inside of the fire-box side sheets. the figure, the crown-bars are placed in a transverse position

DRAWING AND DESIGNING.

152 '

on the crown-sheet, and

as

as the longitudinal length of

many

the sheet will allow, with equal spacing, about 4%' apart. Should these bars be insufficient to support the crown-sheet against the downv/ard pressure of the steam, which to the area of the crown-sheet

then what

inch,

from the outer

and

pins,

X

is

equal

the steam-pressure per square

remains

shell

is held up by .$-/z'#--stays hung and fastened to the crown-bars by links

one link of which

shown

is

at

d

in the transverse

cross-section.

The

upper part of the back-head, which has no staybolts passing through it like those which bind the fire-box and flat

outer shell together, as shown at D,

f" thick, the shape of which transverse section, and to of 3"

X

shown by dotted

is

"

To the

To

between. I

j-" in

lines

many

can be placed on the

irons are bolted longitudinal stay-rods

shown

stiffened with a liner

this liner are riveted as

3" angle-iron as

clearance-space of only about

to that

is

on the lengths

liner,

with a

these angle-

diameter similar

in Fig. 106.

support that curved part of the outside shell just above

fire-box

transverse

stay-rods

C

are

between

carried

each crown-bar, screwed through the shell on each side, and riveted over on the outside.

The body

of the rod

is

\\" in

diameter and the screwed ends ij" diameter.

The

D are

screwed through both box and outer shell and riveted over outside and inside. fire-box stay-bolts

fire-

It

be seen that while the screwed part of the bolt is-J" diameter the body is turned down to J", which reduces its stiffness will

and allows

it

to give

the fire-box and outer

somewhat

to the unequal expansion of

shell of the boiler.

In certain places

the stay-bolts are more liable to break than in others

;

in

such

RIVETS AND RIVETED JOINTS. places hollow stay-bolts are used, so that

may be

easily

Hollow

153

when broken they

and quickly detected.

stay-bolts

have an

-J"

hole

drilled

through from fire-box to the outside of the outer

completely shell, so that"

DRAWING AND DESIGNING.

154 if

one should break the escaping steam and water

will

soon

inform the engineer.

A

detail

view of one of the crown-bar thimbles

is

shown

at G.

Draw

Construction.

the perpendicular centre line 6' 6"

from the left-hand margin, and the longitudinal centre line then draw the transverse and 4' 6" from the upper margin ;

FIG. 107.

longitudinal cross-sections

of

the boiler and

construct the

crown-bars and other staying as shown. It will

be seen

in

the figure that where the plates should

come together they have been left slightly apart this is a convention followed by draftsmen to facilitate inking without ;

blots and to improve the appearance of the drawing.

Exercise 39.

Fig. 106 gives an example of a longitudinal

stay-rod with details and a crow-foot for a locomotive-boiler. / foot. Make the drawings to a scale of 6"

=

RIVETS AND RIVETED JOINTS. Exercise 40.

show examples of box ring (sometimes

Figs. 107 and 108

the corner of a locomotive

fire

155

riveting called a

FIG. 108.

145

:rm

FIG. 109.

and outer shell of mud-ring) to the bottom of the fire-box diameter the boiler. Fig. 108 is that of a large boiler 58"

DRAWING AND DESIGNING.

156

and

carrying

Fig. 107

Make

180

Ibs.

steam-pressure per square inch, and

for a smaller boiler

is

of

48" diameter

at waist.

drawings of both figures as shown to a scale 0/4!'

=

/

foot.

Fig. 109 shows the setting of a tube in the

Exercise 41.

front and back tube-sheets of a fire-tube boiler for a locomo-

Both ends show the tubes swedged, rolled, and beaded, and with copper ferrules between the tubes and the sheets.

tive.

Make full

a drawing like that

shown by the

figure to the scale

of

size.

Fig.

no

is

a section of a locomotive-boiler dome,

ring

C and

steel

and formed

The base and

dome-base B. in dies

by hydraulic

Make half

Fxercise 42

ring are

made

domeof soft

pressure.

sectional elevation, half outside view and plan. Also show the curves of intersection between the dome-base and boiler,

elevation with

Scale 2"

=

transverse

I foot.

CHAPTER

IV.

SHAFTING AND SHAFT-COUPLINGS.

UNDER and

the term shafting

may

be included

line

shafting

axles.

Line Shafting.

This name

is

given to the long line of

rotating, cylindrical or square shafting used' in workshops and

power or twisting moments from the prime movers. They are in some ways an extension of the prime mover. Such shafting is subjected to torsional factories for transmitting turning

and bending stresses, the latter being due to the pull of belts and the weight of pulleys, gears, levers, etc. "It is usual to make line shafting of uniform diameter throughout, as shown in

Fig. ill, enlarged ends being^ only used occasionally for

FIG.

exceptional purposes. of carbon

Steel of a grade containing .3 to .\%

now used almost

is

ence to iron

in

this

in.

country.

entirely for shafting in prefer-

The commercial

shafting for ordinary diameters, as from 1

6

ft.

to 30

ft.,

transportation,

2".

lengths of

to 3". run

from

the shorter lengths being more convenient for for

replacing pulleys,

gears,

etc.

But the

DRAWING AND DESIGNING.

158

when

longer lengths are frequently used arise from these considerations." *

objections do not

Torsional or Twisting Moment. Figs. 112 and 113 a lever, a gear wheel and pinion keyed to their respec-

show

tive shafts; of the gear

R

is

the radius of the lever and the pitch circle

through which the power

force P produces a twisting action on uct RP is called the torsional moment

FIG. 112.

So

R

1

14

P is

multiplied

moment on

torsional

is

transmitted.

(T) on the

R

in

force

is

P

i.e.,

7",

,

and the

again equal to the

is

The

the shaft.

inches

.

FIG. 114.

usually expressed in inch-pounds, into the radius

shaft.

equal to the tension T,

by the

This

the shaft, and the prod-

FIG. 113.

in Fig.

radius

P

torsional

the force

moment

P

in

equal to the torsional

is

pounds

moment

in inch-pounds.

The moment is

of resistance to torsion of a cylindrical shaft

equal to the greatest stress multiplied by the modulus of

the section.

Let

F

t

be the greatest shearing

stress

and

Z

t

the modulus

;

then

T=F Z s

* A.

&

P.

t

Roberts Company.

(I)

SHAFTING AND SHAFT-CQUPL-1NGS.

Z =

and

t

rf'=. 19635^

!

so for cylindrical shafts

T=. 19635^ and

(2)

for square shafts (3)

^=

diameter of the cylindrical shaft and length of side of square shaft

= T=

f,

in inches;

shearing strength in pounds per square inch; torsional

To Shaft.

Find If

we

moment

in

inch-pounds.

Diameter

the

of a

or

Wrought -iron

Steel

take the resistance to shearing for iron equal

to 40,000 Ibs. per square inch and for soft steel at 50,000 Ibs.,

and using a factor of safety of 4^, we have: For cylindrical iron shafts T = I72O
For

cylindrical steel shafts

For square iron shafts

For square

steel shafts

;

T=

2i&2d

T= T=

1849^";

3 ;

231 \d*.

Then for cylindrical iron shafts;

.

.

(4)

1720 for square iron shafts;

...

(5)

1849 A

/2

y

1

82

-

for cylindrical steel shafts;

for square steel shafts.

.

(6)

(7)

DRAWING AND DESIGNING.

l6o

Let the pitch diameter of a spur gear on an iron shaft be 60", and the total pressure on the teeth at the

Example

I.

What would be

pitch line 2500 Ibs.

the diameter

and the horse-power transmitted by the wheel the rate of 140 revolutions per minute ?

shaft at

From

equation

(4)

of

the

running

we get 2500

d=

for the

if

X

3

horse-power transmitted by the wheel.

Let H.P.

=

horse-power

=

number

=

X

33,000

12

=

396,000

inch-

pounds;

n

of revolutions per

minute;

then

H.P.

__

-

-X ^X

6.28

n

=

- -396,000

_

396,000

6.28

X 75>oo X

140

396,000

In terms of the H.P.,

...;-:

r=

63.057 H.P. n

......

and

Besides the twisting stresses on shafts which we have alone

taken account of in the above formulae, there

bending moment

to

be considered.

is

usually a

Let a shaft be subjected

SHAFTING AND SHAFT-COUPLINGS. to a torsional

B\

moment T and

moment moment

supporting a bending

these two stresses will be equal to a twisting

T =+i/(3*+T'). called the equivalent twisting

is

T

be used in place of jected

and

combined torsion

to

stresses

in figuring the

.

.

t

7",

l6l

.^.

moment, and should

diameter of a shaft sub-

The bending

bending.

revolving shafts are continually changing

in

(ii)

from

tension to compression and from compression to tension, so that for combined bending and twisting the factor of safety

4i given

for twisting alone should be increased in the follow-

ing ratio:

When B

is

more than

the factor of safety should be

5

.3

T and

Example

2.

not more than

when over

and when greater than

than T, 5J;

shaft

'

.6

T and

not more

T, 6.

Determine the diameter of a wrought-iron

which has to

resist a torsional

moment

of

400,000 inch-

pounds and a bending moment of 200,000 inch-pounds. formula (11) the equivalent twisting

=200,000+

3

4/20p,ooo +400,ooo

)

-

*'/647,213.5

3~V j.

sional moment. 8

ft.

is

;

When

A

the bending

- 7t

moment exceeds

non-continuous steel shaft has

apart and carries a pulley of 50" diameter

the pulley

in.-lbs.

(4)

r

Example

By

moment

= 200,000+447,213. 5=647, 2 13. 5 and by equation

.67",

its

the

tor-

bearings

at its centre;

driven by a 10" belt, the effective weight and

1

DRAWING AND DESIGNING.

62

belt-pull being 500

and 800

be the diameter of the shaft

What

Ibs. respectively.

should

?

In this case the factor of safety will be 6 and equation (4)

becomes "

+

B =

800

=

800

=

31,200+

7;

X

25

'634

96

=

X

500

= t'3

r.

./

V

(12)

31,200 mch-lbs.

20,000 inch-lbs.

1,

200'

;

;

+ 20,000' = 68,230;

and 68,230

=3 *

,

nearly>

A maximum

Deflection of Shafting.

deflection of

of an inch per foot of length /for continuous shafting

of bare shafting

allowing 40 belts,

Ibs.

=

X

/

=

W, and

loaded

for

given

shafts,

per inch of width for the vertical pull of the

W = i$d*l.

modulus

a

2.-6*/

is

The weight

as good practice by the Pencoyd Iron Works.

Then

for

bending

stress alone, taking the

of transverse elasticity at 26,000,000,

from authoritative formulae the

maximum

we

can derive

length between

bearings

/=

^873^* for bare

/= Vi/5^

3

shafts;

....

for loaded shafts.

.

.

.

(13)

(14)

SHAFTING AND SHAFT-COUPLINGS. For

line-shafting hangers 8

163

apart Thurston gives

ft.

^ d*n

8

H.P. = --3d

H.P.

-

d

=

Hollow Shafts.

is

the

V

**/

shafts,

least

to torsion

resistance

f

for

wrought iron;

weight the hollow shafts are

because the portion of material

effective in

r

for cold-rolled iron.

*

-Weight

stronger than solid

removed

/oo H.P.

\/

in

and a hollow shaft


and

will

Let d

be equal when the moduli of the sections are equal. be the diameter of a solid shaft, and

The

torsion.

resisting

a solid shaft

d^ the internal

and

Then

external diameters respectively of a hollow shaft.

(.fl

A

10" hollow shaft with hollow 4" diameter

less

2.56$

than the solid 10" shaft, but

less.

If

strength only 4.25$

shafts

is

relation

less

than that of the solid shaft, and the

between the weights of

as follows

W

solid shaft

solid

and hollow

:

weight of hollow shaft, ;

weigh

be only

less.

'

Let

will

strength will

the hole were increased to 5" diameter the

weight would be 25$

The

its

and

W

l

=

weight of

then

W

d:

-d d*

(i6)

the weight of the hollow shaft in per cent of the weight of the solid shaft.

DRAWING AND DESIGNING.

164

And

the difference in strength

Let

S=

solid shaft

d*

=

strength of

then

;

=

given as follows:

strength of hollow shaft, and 5,

5

When

is

d? the

d?

weight; and when

=

d*

d

-d

solid

and hollow shafts are of equal

74

74

-

-

-

f

the solid and hollow shafts

are of equal strength.

A

hollow shaft

is

this

is

than a solid shaft of the same

does not yield to bending as an objection under some conditions, as in the

resistance to torsion,

readily;

stiffer i.e., it

case of a steamship's propeller-shaft, where

advantage

if

the shaft would give a

little

it

would be an

to the straining

action of the ship in a storm.

The smaller

larger .hollow shafts are usually forged hollow, but the shafts

are

forged

or

rolled

solid

and then bored

hollow.

SHAFT-COUPLINGS.

We

have seen that shafting is made only in short lengths of about 16 ft. to 30 ft. long, so it is necessary in long lines of shafting to couple

what

is

known

these

lengths together by

as shaft-couplings.

divisions of shaft- couplings, viz., couplings.

on the

means

of

There are three principal rigid, flexible, and clutch

All couplings should be placed close to bearings

side farthest

from the driving-point.

Rigid Couplings.

When two

shafts

coupling that can only be removed

are

joined

by a

by loosening keys or

SHAFTING AND ^HAF7 -COUPLINGS. unscrewing bolts, such a coupling

is

1

65

said to be a rigid or fast

coupling.

Box

or Muff Couplings.

It is

shaft-coupling (Fig. 115). for the shaft

out to is

fit

is

This

cored small

in

the simplest kind of a

is

made

The

of cast iron.

hole

the casting and afterwards bored

The coupling

the finished diameter of the shaft.

secured to the shaft by means of a wrought-iron or steel

sunk key about equal in length to the coupling itself, or by two keys each about half as long as the coupling. The latter

method

the best, because then

;

keyway

keyway

is

shafts

used

not so necessary

in

slacked easier than one long key.

two

it is

both shafts should be exactly the same moreover, the two keys can be driven tighter and

that the

depth

is

the shaft and

cut in

Half the depth of the

half in the coupling.

clearance space should be

a

When two

butt together at the ends.

The

keys are

between them when

left

driven home, to insure an equal tightness of both keys, as

diown

at 5, Fig.

Exercise 43.

115.

Make

a complete working drawing of a muff

coupling like Fig, 115 for a 2\" shaft.

Scale

The dimensions may be found from

full

size.

the following propor-

tions:

=

d

diameter of shaft

= / =

thickness of metal in coupling

t

length of

muff

D= d+2t.

2%'

= 2d +

;

2"

=

.4^

+ J"

;

;

For proportions and taper of key see page in. In some positions of the coupling on the shaft the key should have a gib head, as shown at h

in

Fig. 117,

when

it

is

difficult to

DRAWING AND DESIGNING.

SHAFTING AND SHAFT-COUPLINGS. obtain access to the small end for the purpose of slacking up.

When

the coupling is situated close to the bearing it be necessary to make the length of the keyway to the

of

the

to

equal

coupling

that

half

the

of

will left

corresponding

key. Fig. 116 shows a form of coup-

Split-muff Couplings.

two parts and bolted together on the

ling divided into

shaft,

It is keyed to the sometimes called a compression coupling. shaft with a straight parallel key which fits only at its sides.

The

may be %"

length of the key

and the keyway the same length

as the key.

Make working drawings

Exercise 44

coupling shown

longer than the coupling

in Fig.

1

16 for a 3" shaft.

of the split-muff

Scale 6"

/ foot.

In finishing this coupling the inside faces of the two halves are planed

and the bolt-holes

of sheet tin

the hole

is

Now

drilled.

placing a piece

between the halves and bolting them together, bored for the shaft, making it equal in diameter

to the finished shaft.

The

sheet tin

is

then removed, and the

coupling when bolted on the ends of two shafts clamps them The ease with which the split coupvery tightly together. ling can be

removed and replaced gives

it

a great advantage

over the solid-muff coupling.

Flange or Plate Coupling.

made by

coupling

parts, of cast iron,

tion of the in

key

the other.

key and the holes if

in

desired.

keyed to

the

Fig.

Dodge Mfg. Co.

117 It

shows a plate is made in two

and keyed to the two shaft ends, the posithe one shaft being at right angles to the

The

bolts are turned and carefully fitted,

template so that they can be duplicated Each coupling should be faced after it has been drilled to

its shaft,

so as to obtain perfect alignment.

i68

DRAWING AND DESIGNING.

SHAfTING AND SHAFT-COUPLINGS.

169

DRAWING AND DESIGNING. Exercise 45.

Make drawings

of Fig. 117 as shown, ex-

cept that the upper half of the end elevation shall be a sec-

XX.

tional view through

D = diameter of shaft = 2" Unit = z> + 4"; n = number of bolts = 3

Let

\

(18)

-|

Taking the nearest even number,

d=

diameter of bolt

=

.

n

j

.

.

4

.

(19)

FIG. 118.

The remaining dimensions can be found from tions given in the figure in

terms of

d, the

the propor-

diameter of the

bolt.

The

taper of the

The iron,

but

hub may be made equal to j-" in 12". figure is shown sectioned for wrought

shaft in this

the drawing required

in

it

may be

sectioned with

steel color.

Figs.

1 1

8

and

Clutch Company.

1

19

show

plate couplings

made by

the Hill

SHAFTING AND SHAFT-COUPLINGS. Exercise 46.

of a " Hill for

A

and

"

Make drawings

as required for Exercise 45

plate coupling for a 4J" shaft.

B

to be taken from Table 20.

TABLE

The dimensions The number of

20.

DIMENSIONS FOR THE "HILL" PLATE COUPLINGS. Diameter Shaft.

171

DRAWING AND DESIGNING. drical

form on the outside, but has a double conical section

Two

inside.

sleeves

conical

FIG.

bushes turned to

or

the

120.

inside of the muff and bored out to

together by three bolts.

fit

The

fit

the shafts are pulled

sleeves are split on one side

through one of the bolt-holes, so that the more the bolts are screwed up, the tighter the sleeves clamp the shafts and bind them firmly together. Keys are also used to further prevent slipping.

Exercise 47, Sellers

Make

Scale full size.

clamp coupling.

The

the drawings shown in Fig. 121 of a

taper of the conical sleeve

on the diameter ; e.g.,

if

2%' per foot of length the sleeve was 6" long and the large is

diameter measured 4", the small diameter would measure

For the dimensions

of

the

Sellers

2-f-".

clamp coupling for

various diameters of shaft, use the following table.

SHAFTING AND SHAFT-COUPLINGS.

-r-J

173

DRA WING AND DESIGNING.

174

TABLE

21.

SELLERS CLAMP COUPLINGS.

D

.

SHAFTING AND SHAFT-COUPLINGS.

DRAWING AND DESIGNING.

176

The

outside diameter of the nut. position by means

pieces which

The the

fit

may be made J"

taper of the conical bushes

The

diameter.

lock-nuts are screwed into

wrench having projecting into the recesses shown in end elevation, of a spanner

marked with small

faces

f

in

are

12" on to

be

finished.

The

principal proportions of this coupling are as follows:

d = diameter

of shaft;

D = diameter of muff L = length of muff = Stuart's 123, differs

Clamp Coupling.

2.2$d\ \d.

This coupling, shown

from the Sellers coupling

in

in Fig.

having tapered

FIG. 123.

wedges instead

of conical sleeves; these tapered

wedges and

opposite halves of each end of the muff are bored to the size of

Studs and nuts hold the wedges

the shaft.

in

place,

making, on the whole, a cheap and effective coupling without the us? of keys. Exercise 49.

shown

in Fig.

Make drawings

124 for a

if

shaft.

of a Stuart's coupling cu

Scale

= full size.

SHAFTING AND SHAFT-COUPLINGS.

177

DRAWING AND DESIGNING.

178

The

dimensions of this coupling for various

principal

diameters of shaft are given in the following proportions:

Let d

=

diameter of shaft;

D

diameter of muff;

L= Then

length of muff.

for shafts

from

for shafts

from 2f

D=

I

J" to 2f" diameter

"

up

Flanged Shaft-coupling. shaft coupling in

them on the

L=

^d.

Fig.

125 shows a propeller-

3
which the flanges are formed by forging

shaft.

Make working drawings of the flange coupFig. 125. Assume the external diameter of the

Exercise 50.

shown

ling

in

shaft to be

18" and the internal diameter 10", and take an

equivalent solid shaft as the unit for the proportions.

2

"

=

Scale

T foot.

Let D, and

D

y

be the internal and the external diameter,

respectively, of the hollow shaft; then from equation (15)

we

have

=

=

diameter of an equivalent solid shaft

d=

diameter of bolt;

n

number

R=

of bolts

=

radius of bolt circle

Resistance to shearing of bolts shaft divided

.2$D

by R.

-|-

2

=

unit.

;

.

2

=

resistance to torsion of

SHAFTING AND SHAPT-COUPLINGS.

179

DRAWING AND DESIGNING.

l8Q

From

equation

(2),

>'/,;

and taking f,

at

:

=0

mine

d and

is

d.

evident that

The

-

55

5,

we have (21)

\/5

we must

find

R

following table, by D. A.

before

Low,

n for solid shafts:

TABLE

22.

FLANGED SHAFT-COUPLINGS.

D

.0(20)

50,000 for the steel shaft and 40,000 for the

wrought-iron bolts, and using a factor of safety of

It

.

we can

deter-

gives values of

SHAFTING AND SHAfT-COUPUMGS. While the shearing

C

diameter avoid

the

secure a

C should

bolt,

in

of bolt, yet to

the flanges, and

of tightness in the coupling, the diameter

be made as small as

it is

convenient to

=

thickness of flange

=

F*=

diameter of flange

=-/?

e=D diameter

same diameter

of material

unnecessary use

/

When

resistance of the bolts increases as the

increases with the

maximum

l8l

t

-\".

make

it.

.3/^1 -f- 3;.9
/=4-..

cylindrical heads are

used in tapered bolts their

be J" larger than the largest diameter of the

may

and the height equal to |^.

FIG. 126.

Clutch Coupling. This coupling, shown in Figs. 126 and 127, is such that one half may be, geared with or disgeared from the other half at will, and for slow-moving shafts

Jaw

this

arrangement

is

simple and effective.

Make drawings as shown in Fig. 127 for a diameter. The other dimensions may be taken

Exercise 51. steel shaft 3"

from Table 23. Spiral-jaw Coupling.

This form of coupling, shown in

Figs. 128 and 129, has axial engagement and

is

the

commonest

182

DRAWING AND DESIGNING.

SHAFTING AND SHAFT-COUPLINGS. TABLE

23.

JAW CLUTCH COUPLINGS. (Dimensions are

d

in inches.)

183

1

84

AND

DESIGNING.

SHAFTING AND SHAFT-COUPLINGS. Make drawings

Exercise 52.

of a spiral-jaw coupling for

a 2\" shaft, as shown in Fig. 129.

The flexible

Scale 6"

Joint, the

best

is

couplings

"If not the

:

known

i foot.

common

Hooke's

as

of

coupling.

original inventor of the Universal

Cardan was the

Italian

=

This most

Universal-joint Coupling.

Reuleaux says

185.

to describe

first

it

(1501the Hooke and first Englishman 1576), (1635-1702) applied for the transmission of rotary motion." it The practical value of this form of coupling

that

is

it

can be used to con-

nect two shafts whose axes intersect, and the angle between

the shafts

be varied during rotation

may

makes

it

flexure

due to the

;

this latter feature

suitable for ship propeller-shafts, to allow for the elasticity of the hull of the vessel.

The coupling shown

in

Fig. 130

is

called a double-joint

coupling because of the intermediate piece shown at S, and is

such that two shafts

angles with

in

uniform angular velocity.

Dodge Mfg.

This coupling

nut

coupling,

is

Md.

wrought

Exercise 54.

designed

The steel.

by the

made by

with the

and

as

shown

in Fig.

Campbell

The

design

Make drawings

(2 i)

&

Zell

Co.,

material of the coupling and coupling-

that the diameter of the bolts

will

rotate

is

Fig. 131 shows a. propeller-

is

neat, compact, compara-

tively inexpensive, and has given good

tions (20)

will

I foot.

Propeller-shaft Coupling.

Baltimore,

(S)

Make complete drawings

=

Scale 6"

shaft

piece

Co., Mishawaka, Indiana.

Exercise 53 130.

the same plane and making equal

intermediate

the

satisfaction.

of Fig. 131 as shown, except is

to be calculated

by equa-

(so that the resistance to shearing of bolts

be equal to resistance

to torsion of shaft

divided by R).

1

86

DRAWING AND DESIGNING.

SHAFTING AND SHAfT-COUf'LINGS.

I8 7

1

DRAWING AND DESIGNING.

88

and make the diameter of the bolt-centre diameter of the coupling to In equation (20) use

D

suit.

circle

Scale 6"

equal to the

=

and the outer

i foot.

mean diameter

of the

tapered part of the shaft, and from the result of equation bolt diameter found in (21) take the nearest commercial

Table

8.

CHAPTER PIPES Pipes are

V.

AND PIPE-COUPLINGS. made

of cast iron,

wrought iron, steel, and used to convey steam, water, or gas. Copper pipes are used most largely in marine work, and brass Pipes.

copper, and

brass,

pipes or tubes are used to

some extent

in

Europe

for the fire-

tube boilers of locomotives and for other purposes. Thickness of Pipes to Resist Internal Pressure.

Let

D=

internal diameter of pipe or

mean diameter

for

very thick pipes; /

=

length of pipe in inches, inside of flanges;

P= internal pressure

in

pounds per square inch;

thickness of pipe in inches;

/

f= t

safe

stress

tensile

in

material

in

pounds per

square inch.

Then the shell

the total force tending to separate two sections of

=PX D X

nesses of the shell

X

/,

which

is

by the two

resisted

the length of the pipe

X

thick-

the pressure

per square inch, or 2 (/(/<); from this we get

*

= PD Tf

.

.

.

.

This formula gives a thickness somewhat

... less

than

.

-co

is

used

in practice. 189

DRAWING AND DESIGNING.

190

D. A.

Low

gives

_PD +C ,

k

and the values of k and

c as follows:

TABLE

24.

'

'

(2)

PIPES

= C= d

= w= n

W=

AND

PIPE-COUPLINGS.

igl

+ 4.25; 1.092/7 + 2.566; o.on/7 + 0.73; 1.125/7

number weight

"

= 0.78/7+ 2.56; of pipe per foot = 0.24/7* + 3/7; flange = .ooi/7 + o.i/7 + /7 + of bolts

8

ll

This joint has the flanges faced

2

all

over,

pressures up to 75 Ibs. per square inch (170

and

ft.

is

2.

used for

of head); for

FIG. 131.

higher pressures the joint may be made with a string smeared with red lead between the flanges or a lead, india-rubber, or gutta-percha ring. Exercise 56.

Make drawings

coupling, Fig. 132.

of a cast-iron-pipe

flange

Inside diameter of pipe to be 9", other

dimensions to be taken from Table 25.

Scale 6"

=

I foot.

DRAWING AND DESIGNING.

FIG

132.

TABLE

25.

STANDARD CAST-IRON FLANGES. (.Dimensions are in inches.)

PIPES

AND

PIPE-LOUPLINGS.

I3>

Spigot-and-socket Joint. This is the usual joint for pipes that have to be embedded in the earth for conveying water or gas.

Fig. 143 shows a joint of this kind.

About

between the spigot and socket is first filled' with rope gasket and into the remaining half is poured molten* lead, which when it cools is calked tightly into the socket half of the space

with a

hammer and round-nosed

FIG

Exercise 56^.. ling for

tool.

133.

Make drawings

of a spigot-and-socket

coup-

an 8" cast-iron pipe carrying a pressure of 100

per square inch (Fig. 133).

Same

elevations

and

Scale 6"

I foot.

Calculate the

Ex. 55.

sections as in

dimensions from the following proportions:

D= t

=

internal diameter of pipe;

thickness of pipe

= PD ft

' .

f-

Ibs.

c

from equation

(2)

;

DRAWING AND DESIGNING.

194

C= /==

.

i";

.

Make working drawings

Exercise 57.

for the spigot-and-

socket cast-iron pipe-coupling shown in Fig. 134.

diameter of pipe

Ex. 55.

10".

Scale 6"

=

Elevations,

and

'sections

Internal similar

to

i foot.

FIG. 134.

The dimensions

for this

the proportions given part

E is made with

Exercise 58.

Ex.

55.

problem are to be calculated from Ex. 56. The turned and fitted

a taper of f" in 12"'.

Make working drawings

pipe flange coupling as in

for

like

Scale 6"

Fig. 135.

of

an 8" cast-iron-

Elevations and sections

i foot.

Dimensions to be taken from Table 25.

PIPES

AND

PIPE-COUPLINGS.

'95

These pipe-ends and flanges are strengthened with ribs drawn at an angle of 45 with the axis of the pipe, and the

FIG. 135-

joint

equal

is

in

made by means

of fitting- strips cast

width to the thickness of the pipe.

on the flanges

The

faces of

these strips are finished perfectly square with the axes of the pipes, and before bolting

Exercise 59. for a

up are smeared with red

Make drawings

copper pipe shown

pipe 8".

Scale 6"

This joint

is

=

in

lead.

of the loose flange coupling

Fig. 136.

Inside diameter of

/ foot.

the invention of Mr. R. B. Pope of

FIG. 136.

Dumbar-

DRA WING AND DESIGNING.

196 ton, Scotland,

rings

may

or cast

and

is

Low

given by

The

and Bevis.

be made of cast iron, wrought iron, wrought

steel;

the latter

is

It

preferred.

is

flange steel,

evident from

Fig. 136 that the rings must be placed on the pipes before

the ends are flanged.

These

joints

exhaust-pipes from

have ij-"

been

used

for

feed-,

and

to 36" diameter.

The dimensions may be taken from TABLE

the following table:

26.

POPE'S PIPE COUPLINGS. (Dimensions are

D

steam-,

in inches.)

PIPES

AND

PIPE-COUPLINGS.

197

FIG. 137.

The " Converse"

joint for wrought-iron

and

steel pipes is

manufactured by the National Tube Works, McKeesport, Pa. This joint consists of a cast-iron there are also sleeve with a space for lead at each end

shown

at Fig.

138.

It is

;

internal

recesses plainly

shown

in Fig.

138, into which are

FIG. 138.

inserted rivet-heads on the ends of the pipes, and of the pipes the flanges

become locked

in position.

by a turn Molten

poured into these recesses around the rivet-heads and tightly calked at the ends of the sleeves, as shown in Fig. 139. lead

is

DRAWING AND DESIGNING.

198 Exercise 61.

Make drawings

of the Converse joint for a

7" wrought-iron pipe, according to the dimensions given in Elevations and cross-sections same as in Ex. 55.

Fig. 139.

=

Scale 6"

i foot.

FIG. 139.

Screwed flange Pipe -coupling. Fig. 140 shows a wrought-iron pipe-joint made by screwing cast-iron flanges on the ends of the pipes and held together by bolts. It is

used by the Philadelphia

The

their steam-pipes.

are

made according

& Reading

Coal and Iron Co. for

threads of the screws on the pipes

to the Briggs standard.

The

lugs

in the figure on the right-hand flange are cast on,

their inner surfaces finished to

on

the other flange.

of

gum

are

The

ring

fit

in lengths of

Exercise 62.

shown between the

from 16 to 20

Draw

and have

the cylindrical fitting-piece

rubber and makes the joint steam-tight.

made

shown

flanges

The

is

pipes

ft.

a screwed-flange

pipe-coupling like

=

Scale 6" i foot. Fig. 140 for an 8" wrought-iron pipe. Dimensions may be taken from the following table :

PIPES

AND

PIPE-COUPLINGS.

199

200

DRAWING AND DESIGNING. TABLE

27.

NNECTIONS OF PHILA. & READING COAL AND IRON CO. (Dimensions are *o

i^

in inches.)

PIPES

AND

PIPE-COUPLINGS.

201

which conducts the steam from the dome and drypipe to the steam-chests of the cylinders on each side of the engine. The pipes are of cast iron, and the spherical joint-ring pipe

(b)

is of brass.

tion

and

The

ball joint allows for

for the pipe

to

expansion and contracbe set at various angles with the

perpendicular and horizontal.

DRAWING AND DESIGNING.

2O2 Exercise 64.

Make

drawings, as shown by Fig. 142, of a

locomotive steam-pipe ball joint to dimensions given. 6" i foot.

=

Scale

PIPES

AND

PIPE-COUPLINGS.

Wrought-iron Flange Pipe-coupling. a pipe-coupling made with angle-iron for a angle-iron pipes.

is

rolled

7/hese

203

Fig.

143

shows

steel pipe.

The

and welded into rings and riveted to the are

flanges

used for either wrought iron or

T

FIG. 143-

steel

pipes.

The

is

joint

made

steam-tight by means of a

lead ring inserted between the flanges as shown.

Exercise 65.

Make drawings

of a steel pipe with

iron flange coupling like Fig. 143.

diameter.

Nominal

wrought 8"

size of pipe

Elevations and sections like Ex. 55.

Scale 6"

=

I

foot.

Couplings for Brass and Copper Pipes. The coupling shown in Fig. 144 is used on locomotive-boiler feed-pipes, injector-pipes, etc.

The

sleeves (a) and (b] are brazed to the

pipes, and a thin copper gasket placed between the ends

the sleeves makes the joint thoroughly tight

up with the

fluted nut

Exercise 66.

of

when screwed

(c).

Make

drawings, as shown in Fig. 144, of a

brass pipe-coupling, outside diameter to be 2\" size.

The dimensions may be taken from Table

28.

.

Scale full

DRAWING AND DESIGNING.

204

a

TABLE

28.

COUPLINGS FOR BRASS, COPPER, AND (Dimensions are

d

WROUGHT IRON

in inches.)

PIPES.

PIPES

AND

PIPE-COUPLINGS.

TABLE

__JL

7854AB .0982BA

29.

205

CHAPTER

VI.

BEARINGS, SOLE-PLATES, AND

ALL pieces employed

in

WALL BOX-FRAMES.

the transmission of power, rotating

about a geometrical axis,

must be supported

as to allow free rotation.

The supports

name

in

such a manner

receive the general

of bearings, the various types being designated accord-

When

ing to the direction of the pressure acting upon them.

the pressure

is

perpendicular to the axis of the shaft they are

when bearings of this type and the framework connected with them are independent parts of a machine, they are indiscriminately called Plummer Blocks, Pillow

journal-bearings, and

Blocks, or Pedestals.

When

the pressure

is

parallel to the axis of the shaft

and

the shaft terminates at the bearing surface, Fig. 164, the bearing

is

a pivot-bearing.

When

this

type of bearing

for supporting the weight of a vertical shaft,

step- or footstep-bearing.

When

the pressure

the axis of the shaft and the shaft bearing, the latter

Wnen

pivot- or

is

it

is

is

employed

is

termed a

is

parallel to

continued through the

termed a collar-bearing. collar-bearings

are

used

on horizontal

shafts they are called thrust-bearings.

Journals are the parts of the shafts or axles that revolve on

the

bearings.

spherical, of

They

are

made

which the cylindrical

is

cylindrical,

the most

conical,

common 206

or

form.

AND WALL

BEARINGS, SOLE-PLATES,

To

BOX-FRAMES. 2O/

motion of journals the shafts are turned down or have collars forged upon them to form limit the longitudinal

come

shoulders which

with the faces of the bear-

in contact

When

upon which the journals revolve.

ings

practicable the

length of journals should be about one per cent greater than that of their bearings.

The' Area of a Bearing is the width of the chord of the arc in contact with the journal, multiplied by the length of the bearing. area, because

on

a

to

DX

is

The

.

4

D

is

sometimes called the projected

is

the area of the contact surface projected

plane perpendicular to

Thus the

sure.

164,

is

it

This

area of a cylindrical journal-bearing, Fig.

The

L.

area of a pivot- bearing, Fig. 278,

area of a collar-bearing

the diameter of the shaft

collars

and

N the number of

is

made by

D

is

4

is l

/V) N.

(D*

is

Where

the outside diameter of

collars.

Solid Journal-bearings.

bearing

the direction of the pres-

The

drilling a hole

simplest form of journal-

through the frame of the

machine, and to provide sufficient bearing surface the length of the bearing is increased by casting projections, which are

termed bosses, upon the frame, as in Fig. 145. In this form of bearing there is no provision for wear, and the shaft can be returned to

its initial

by renewing that part

position only

of the frame that carries the shaft, or, oval, reboring the bearing sufficiently to cal sleeve or bush, as in

Fig. 146.

when the fit it

Such

hole wears

with a cylindri-

a bearing

may be

provided with a

bush or lined with

be restored to

original condition by renewing the bush or

lining.

its

The end movement

soft

of the shaft

metal, and can

may be

limited

DRAWING AND DESIGNING.

208

by making the diameter

of one of the journals less than the

diameter of the shaft, thereby forming a shoulder which limits the end

movement

in

one direc-

tion, and securing a separate collar to the shaft, by means

of a set-screw or taper-pin, in

such a position as to limit the

end movement

shown

direction, as

Another method the

shaft

the

in

other

in Fig. 145.

to

is

make

uniform section

of its

throughout length, limiting its end motion by means of

two separate

collars

be arranged

in

which may

three different

positions.

Exercise

Draw two

67.

solid journal-bearings support-

ing a shaft 2" in diameter, mak-

ing the area of the bearing surface 6 square inches,

and show

an arrangement for limiting the

end movement

in either direc-

by means collar, as shown

tion

of

one loose

in Fig.

145.

Draw also one bearing if" in diameter with a brass bush or sleeve,

Make

/

equal

.to o.-id

+ iV'-

as

shown

in Fig.

146.

Parts dimensioned in decimal

BEARINGS, SOLE-PLATES, are

fractions

AND WALL BOX-FRAMES.

proportional to d.

Complete and

in

the

Scale full size.

actual dimensions to the nearest sixteenth.

As

fill

209

the shafts supported by solid journal-bearings cast with

the machine-frame have to pass through one bearing to the other, this form of bearing cannot be used

A

projections on the shaft.

when

there are

can be used, how-

solid bearing

upon which there are projections, by making the bearings independent parts and securing them to the machine-frame by means of bolts. By this arrangeever, for supporting a shaft

ment the

Fig.

turned

is

down on

and one of the bearings

journals,

before

shaft

is

it

147,

is

the ends to form the

placed on

its

journal

This form of bearing,

secured to the frame.

consists of a hollow cylinder cast

upon a base

through which bolts are passed into the machine-frame or supporting bracket. Fig. 147 shows a design of a solid journal-bearing used for

supporting the valve-gear reversing-shaft of a locomotive. Such a bearing can be used for this purpose because it is subjected to a comparatively light load, while the journal has

The

a slow and intermittent movement. of the bearing in this design are

length and shape

determined by

local condi-

tions, the bearing being carried forward further on one side

of the base than on the other to suit the shaft.

of the base

and

is

is

The width

determined by the thickness of the frame,

provided with

strips

on the under side to

facilitate

fitting.

Exercise 68.

Draw

an

journal-bearing of the form

2^" and

L=

2d.

The

are proportional to d.

elevation and

shown

plan of a solid

in Fig. 147,

parts dimensioned

Scale full size.

in

making d

=

decimal fractions

DRA WING AND DESIGNING.

210

Construction.

First

draw the centre

the cylindrical part of the bearing.

and complete Make the distance a lines

equal to the outside radius of the cylindrical part

-\- r,

the

FIG. 147.

radius of the

fillet,

which we

will

make equal

half the distance across the angles of the nut

ance.

The

distance b can be

across the angles of the nut

Divided Bearings

made

to, say,

-f- -J"

J"

-j-

for clear-

equal to half the distance

+'.

Where

the conditions are such that

the shaft cannot be placed upon

its

bearings endwise, the

bearings are parted and the parts fastened together by means The division is generally made on the of bolts or screws. line

normal to the resultant pressures on the bearing.

BEARINGS, SOLE-PLATES, III

Fig, 148

bearing. is

is

shown what

It consists of

AND WALL

211

generally termed a two-part

is

the block P, upon which the^jodrnal

supported, and the cap C, which

the bolts CB.

BOX-FRAMES.

is

secured to the block by

In this design the journal

lubricated with semi-liquid grease which

is is

intended to be passed through

The bearing is lined with Babbitt metal, The holes through which the holdingthick. pass are made oblong to horizontally adjust the

the opening O. .c3Z>

+ Ty

down

bolts

pedestal.

Wall Box-frames

are built into the wall for the purpose

which passes from one Fig. 149 shows a wall box-

of supporting a bearing for shafting

room

or building to another.

frame with an arched top to support the wall above

On

it.

FIG. 149.

the sides are cast projecting webs

keep the frame from base

is

W which

moving endwise.

fit

provided with raised machined strips

the pedestal rests, as

shown

in Fig. 150,

into the wall to

The upper and

side of the

FS upon

at each

which

end of

this

surface are projections S, on the sides of the frame, which are also

machined.

wooden keys the surface

To

adjust

the

pedestal

of the necessary thickness are

5 and

the pedestal base.

The

horizontally,

fitted

height

H

between is

equal

DRAWING AND DESIGNING.

212

to the highest point of the pedestal cap

CB -f-

the cap-bolts

The

the cap. the

amount

when

raised clear of

about 6" to allow the engineer to remove

length

/,

is

equal to

/,

the length of the base,

+

of horizontal adjustment allowed on the pedestal

?

FIG. 150.

-f-

y

The width

f

wall,

.

which

is

w

is

made

to suit the thickness of the

usually built to average from 8" to I2

proportioning of such a piece

is

r> '.

The

largely a matter of experi-

none of the parts being calculated for strength. Draw a pedestal and wall box-frame Exercise 69.

ence,

of the

designs shown in Figs. 148 and 150, placing the pedestal in position on the wall box-frame, to which

square-headed bolts

Make

base.

length 8".

L

secured by two

the pedestal to suit a shaft 2\" in diameter, the

equal to $D, and the width

Show

it is

the heads of which project below the

w

of the frame equal to

a half-elevation and half-sectional elevation of

the pedestal, and an elevation of the wall box-frame, also a

plan view of the pedestal with half of the cap removed, and in combination with this view show a section of the wall box-

frame at the

line

AB.

Make

also an

end view

of the pedestal

BEARINGS, SOLE-PLATES, and a sectional end view

AND WALL BOX-FRAMES.

of the wall box-frame.

the pedestal are proportional to the diameter Fill in all

dimensions omitted.

Draw

Construction.

213

All parts of

D of the journal*

Scale full size.

the vertical

and horizontal centre

then determine the distances from centre

lines of the journal,

by drawing the the cap-flange, and the arc

which represents which represents the

to centre of the bolts

line

the top of

2,

I

The centres of now be determined by making the corners

top of the cap at the centre of the bearing. the cap-bolts can of the nuts from lines

i

and

^"

It is

2.

which joins the obvious that the bolts may be brought to

\" clear of the

fillet

nearer together by either increasing the thickness of the capflange or cutting out the curve 2 around the nut, but on small

pedestals for line shafting this is

made

-j-

i"

is

The

unnecessary.

radius r

equal to half the distance across the angles of the nut

for finish.

holding-down

The

bolts

is

distance from centre to centre of the

equal to the distance b

-f-

the horizon-

diameter of adjustment (equal to the length of the hole bolt) -)- the diameter of the washer-)- the radii of the fillets,, tal

which may be made equal to about J". Determine the radius r of the arched top of the wall box-frame by making e

V, the versed sine of the arc, equal to

>

Half the elevation

method employed with the shaft,

is

.

4 sectioned, to show more

clearly the

keep the Babbitt lining from turning the form of head on the cap-bolts, and also to

through which the cap-bolts The plan view is^ pass is greater than the bolt diameter. shown with the cover removed from one side of the bearing, that the diameter of the holes

to

show the form

of that part of the bearing through which.

DRAWING AND DESIGNING.

214

The

the shaft passes.

fitting-strips

base are of the same proportions as

When

it

practicable

the bearing

is

on the under side of the in

the previous exercise.

usual to provide the piece to which

fastened with fitting-strips also, as in Fig. 150.

is

Post Bearings.

When

a vertical surface, the base

the bearing has to be secured to cast

is

on the

In the design shown in Fig. 152

Fig. 151.

shown

side, as it is

in

necessary to

provide the cap with four bolts because of the webs W, which

way cf the bolts being placed on the centre as The bearing is arranged in this case for two 148.

are in the in Fig.

grease-cups, which are screwed on to the cap at the tapped

The

holes O.

cap-bolts are kept from turning

are being screwed

down by

when the nuts

projections h cast on the under

side of the box.

Exercise 70. section, as

shown

Draw

the elevation and an end view half in

Draw

in Fig. 152.

from

top projected

Make D.

D

view

also a plan

2f ", and

Parts not

of the

the elevation.

L=

three times

dimensioned are

the same proportion to

in

as in the

Scale half size.

preceding exercise. Construction.

D

Draw

the centre

lines of the bearing, taking care t6

leave sufficient space to plan.

Mark

off

draw the

the distance that

the bearing projects from the post, then determine the length and width FIG. 151.

bolts

PB

should be

of the washer

+ i"

of the base.

The

centres

of

the

in a distance at least equal to the radius

from the ends of the base.

BEARINGS, SOLE-PLATES,

AND WALL BOX-FRAMES.

FIG. 148.

FIG. 152.

21$

DRAWING AND DESIGNING.

216

adjustment a is made equal to ij". As the " greater than the oblong holes are cored, the width e is the bolts. diameter of

The

vertical

Wall Brackets

are

to carry pedestals

employed

which

support a horizontal shaft running parallel and near to a wall. The bracket, Fig. 153, is fastened to the wall by means of three bolts which pass through

it

and the

The

wall.

pedestal

f BOLTS.

FIG. 153-

is

secured to the upper surface by square- or T-headed bolts

which

slide

in

the

.Z

-shaped slot

5 which

runs the whole

length of the bracket. By this arrangement the distance that the pedestal is from the wall can be adjusted.

Draw a wall bracket to the Make the slot 5 suitable for a

Exercise 71 in Fig, 153. bolt.

JJraw also

a section,

through the bracket at the

line

proportions given J-"

square-headed

the plane of section passing

AB.

Scale half

size.

BEARINGS, SOLE-PLATES,

AND WALL BOX-FRAMES.

SELF-ADJUSTING BEARINGS. Bearings for supporting line shafting

two

classes,

Rigid and

may be

When

Self-adjusting.

divided into shafting

is

supported upon a number of rigid bearings it is essential that they all be in line, one with another, in order that the pressure be distributed over the entire surface of each.

This is " " with of the form bearings rigid possible having compara-

tively long boxes

when they

when

are rigidly supported, but

supported upon insecure foundations, which are liable to sink, the bearing will assume such a position in relation to journal as

is

shown

in Fig. 154,

where the entire load

is

its

carried

DR.

FIG. ISA-

upon a small portion of the bearing. also

Such a condition

where the distance between the bearings

is

exists

great in

com-

parison with the shaft diameter, owing to the lateral deflection

by the gearing. Under such conditions the oil is forced out from between the rubbing surfaces, causing the

of the shaft

metals to heat and seize by metallic contact.

To

avoid this localization of

ball-and-socket

joint

are used,

pressure,

which

to

bearings a

limited

with a extent

adjust themselves to the various positions of the shaft, so that

DRAWING AND DESIGNING.

2l8

the axis of the bearing will always coincide with that of the journal.

This form of bearing makes

it

practical to use a long box,

thus keeping the pressure between the journal and bearing

enough

light

unbroken

to retain an

the rubbing surfaces.

With these conditions the boxes may

be made of cast-iron, which the

cated,

between

film of lubricant

is

the cheapest and,

most desirable metal

for

the

if

well lubri-

purpose.

Many

engineers, however, prefer to line these boxes with a white metal which rapidly wears and adjusts itself to any irregularities

on the journal, making a perfect bearing more rapidly Again, with

than would be the case with a harder material. the cast-iron box, should the lubricant

come

and the metals

contact^ they will adhere and destroy the journal,

in

while,

fail

under the same conditions, the babbitt metal would

melt without materially injuring the shaft.

When

Drop Hanger-frame. head and

is

a shaft

Two

forms are used, the

bearing on both sides, as shown braces one side only.

The

objection to the

difficulty

in

supported over-

not near a wall the bearings are carried upon a

frame, called a hanger frame, which girders.

is

U

is

U

secured to the ceiling

form, which braces the

in Fig.

155,

and the

J,

which

form as commonly made is the in and out of the hanger.

getting the shafts

This has been

overcome

to

some extent by making the

hangers open at the bottom of the U, as

it

were, and connect-

ing the sides with bolts.

The

J

form has the advantage of

and dismounting of the

shaft, but

made comparatively heavy.

facilitating the

is

mounting

liable to vibrate unless

BEARINGS, SOLE-PLATES,

AND WALL

Fig. 156 shows a hanger

made by

the

BOX-FRAMES.

Dodge Manufac-

turing Co. which combines the advantages of

This

is

attained

both forms.

by making the hanger open on one tl

2 19

side

and

which are

split, and by providing bolts LB, drawn together upon taper cones C, cast on the it

with detachable links L,

FIG. 155-

hanger frames F, which match corresponding recesses in the These links are thus drawn up to a positive parts of the links. bearing and form a connection which is virtually solid, and yet they are easily removed and replaced." Fig. 1 56 shows a shaft with an is carried between which hanger adjustable bearing B,

P

and P', called the plungers. These plungers are screwed into the frame F and serve a double purthe adjusting screws

pose;

first,

they are a means of obtaining a vertical adjust-

DRA WING AND DESIGNING.

220

they provide the sockets, with which the spherical surfaces on the box engage, to form the ball-andThe plungers are locked in position by the setsocket joint.

ment

;

second,

The

screws S.

bearings are lubricated 8f

by

filling

the cups

-

T

FIG. 156.

O

and O' with grease, or cotton saturated with oil. The drippings of waste oil from the box are caught in the oil dish

OD

attached to the frame by hooking the head over the pin

P, which

is

cast

Exercise 72.

on the frame.

Draw

the front and

end elevations

partly in

BEARINGS, SOLE-PLATES, section, as

shown

in

AND WALL BOX-FRAMES.

Fig. 156, a half plan

plan of the side to the right,

through the hanger

Draw

and

221

a half-sectional

the plane of section passing

at the centre line.

Scale half

size.

also full-size sections of the frame, the plane of sec-

tion passing through the hanger at the lines

AB, CD, and EF.

Fig. 157 shows Sellers method of forming the ball-andThe plungers socket joint on adjustable hanger bearings. P and P' have shallow threads which extend along a portion of the plungers, while the threads in the boss are cut the entire

The

length of the boss.

plungers are locked in position by

the set-screws S, the points of which are the plain

part

the

of

plungers

them with cotton saturated with conditions,

ings

O

to press against

below the threads.

and are used

plungers are cast hollow,

made

oil,

as lubricators

and O' are

filled

filling

which, under ordinary

sufficient to lubricate the journal.

is

by

The

with tallow which

is

The open-

solid at ordinary

temperatures but melts should the bearing become heated.

The

outer end of the

plungers has

a

hexagonal hole to receive a key by means of which the screw is turned when

adjusting the bearing. Exercise 73.

the

Design a hanger- frame and bearing, altering

frame shown

in

Fig.

156 to suit the arrangement of

plungers and bearing shown in Fig. 157, and design a method of fastening a drip-catcher to the frame, other than that

shown

Figs. 155 and 156, which must be so arranged that it can be easily removed and replaced. Show a complete FRONT in

ELEVATION, SECTIONAL END VIEW, and PLAN projected from the front elevation.

Make

D=

proportions

is

2\" and length of bearing

1.4

,

D

-f- .2.

Scale half size.

=

4 D.

Unit oj

222

DRAWING AND DESIGNING.

FiG. 157

BEARINGS, SOLE-PLATES,

AND WALL BOX-FRAMES.

223

Wall- or Post-hanger is employed to serve the same purpose as the Wall bracket with its separate pedestal. The frames of these hangers are designed on the same -

FIG. 158.

general lines and principles as the drop hanger-frames

shown

This hanger is shown in Fig. 158, with and without the double brace links, fitted with chain lubricatingin

Fig. 156,

bearings of the design shown in Fig. 160.

Draw FRONT ELEVATION and two END shown in Fig. 159, and a PLAN VIEW projected from

Exercise 74

VIEWS

as

the front elevation.

Scale 8" to the foot.

Show

also full-

sized sections, the plane of section passing through the frame at the lines

AB, CD, and EF.

DKA WING AND DESIGNING.

FIG. 160.

AND WALL BOX-FRAMES.

BEARINGS, SOLE-PLATES,

22$

Chain Lubricating-bearing. This type of bearing is designed to be lubricated by means of endless chains C which hang over the

shaft,

and

passing through the each end of the box.

C

chain

revolves the chains revolve with

in

the reservoirs

formed

oil

at

which

adheres by capillary attraction,

carried to the shaft, spreading through the channels

is

O C to

all

parts of the bearing.

All surplus

the oil reservoirs, to be used again until dirty,

OR

consists of a series of parallel links

form surfaces to which the and

it

oil

it,

The

as

and

is

then drawn

off

it

oil falls

back into

becomes thick or

by removing the plugs

5.

Draw the chain lubricating-bearing shown in showing a HALF ELEVATION and HALF SECTIONAL

Exercise 75. 161,

,Fig.

ELEVATION; an END VIEW projected from the right HALF SECTIONAL END VIEWS projected from the left-hand end, the plane of section passing through the bearing at the lines

AB

and CD, and a PLAN with half of the upper box reScale full size. Draw also an ELEVATION AND

moved.

PLAN

of a part of the lubricating chain as

shown

in Fig.

163.

Scale four times full size.

shows a method of finding the the chain represented in the end-view in position

Construction.

centres of

on the

shaft.

Fig.

162

In this construction the centres

on the curve unless from the points is

small.

At

I

to 2,

may be taken

where the radius

this part step off chords equal in length to the

pitch of the chain, and,

parallel

to the chords,

draw

lines

The intersection of the tangent lines tangent to the arcs. the of the chain at that part. as centres taken be may

226

DRAWING AND DESIGNING.

AND WALL BOX-FRAMES.

BEARINGS, SOLE-PLATES,

22J

Bushes, Steps, or Brasses are names given indiscriminately to the bearings proper,

i.e.,

the brass or bronze parts,

that are in contact with and support the journal.

a

means

of taking

up the

lost

They

afford

motion due to wear, thus

insur-

will have the reing that the journal with which they engage They must be made of quired motion about the given axis.

a material that will allow the journal to run

with a

minimum amount

of friction,

without wearing the journal.

yielding.

When

will

They must

strength to resist the stresses that

undue

and

in

also

contact with

it

withstand wear

have

sufficient

come upon them, without

supporting a wrought-iron or steel

shaft, gun-metal, to a limited extent, fulfils all these require-

ments.

Other metals possess some of these qualities

higher degree without having them all. " White metals, such as babbitt's or '

*

* '

in

a

"

magnolia

metals,

and their surfaces may be destroyed without injuring the surface of the journal (as would be the case with the bronzes), but they are too soft to be offer less frictional resistance,

used alone unless subjected to an exceptionally light load.

The

position of the bush in

the supporting frame depends

upon the direction of the pressure. ings the resultant pressures are all lost

parts.

in

In the majority of bear-

one or two directions, and

motion can be taken up by making the bearings

The

in

two

ordinary forms of two-part bearings are shown

The forms shown in Figs. 164 and 165 n Figs. 164 to 167. are turned, and the supporting frame is bored with a cylinwhich the bearings are fitted. To prevent these forms from rotating with the shaft they are provided drical hole

into

with rectangular lugs L, as in Fig. 165, or with steady pins P, as in "Fig. 164.

DRAW1-NG AND DESIGNING.

s

AND WALL BOX-FRAMES.

BEARINGS, SOLE-PLATES,

The

may

pins

The forms shown octagonal and

be either cast with the bush or driven Figs. 166

in

planed to

it

become hot

and 167 are

The square form

it is

To

unequal distribution of metal.

machining on bearings,

cast square or

is

the cheaper, but

be distorted, owing to the

liable to

facilitate fitting,

and reduce

them

usual to support

is

it

in.

correspondingly shaped surfaces in

fit

the supporting frames.

should

229

at their

ends only, by forming projecting faces F S at each end. This may be done successfully on small bearings subjected to a steady load, but on crank-shaft bearings

The

support them over their length.

is

it

advisable to

bearings should be

divided on a line normal to the resultant pressures and, as

they will wear very

little

at that

part, they

thinner than at the part where the pressure

keep the bearings from

fits,

shown

as

brickwork

is

it

in Fig.

When

Sole-plates.

is

made

be

To

greatest.

laterally along the shaft they between which the supporting

moving

are provided with flanges F,

frame

may

169.

a pedestal

is

secured to masonry or

necessary to spread the pressure upon the

journal over a large surface.

For

this

purpose a Sole- or

These usually consist of a flat castiron plate with a bevelled surface upon which the pedestal can be adjusted horizontally by means of the wood keys K, which Base-plate

are driven

is

employed.

in

between the joggles

pedestal base, as

shown

in

J

Fig. 169.

and the ends

The

pedestal

of the is

fast-

ened to the sole-plate by the bolts P B, which pass through The sole-plate is secured to it and the base of the pedestal. the foundation by the bolts

F B.

The width

plate should be equal to (a) width of

amount

of

movement

(b)

of the sole-

pedestal base

of pedestal along shaft

-f-

say

".

-f-

the

DRAWING AND DESIGNING.

23O

Adjustable Base-plates are used for adjusting bearings The vertical adjustment is made vertically and horizontally.

by

sliding

wedges which may be arranged either

in Fig. 168) or longitudinally.

The

laterally (as

horizontal adjustment

is

FIG. 168.

by means of set-screws which take the place wooden keys shown in Fig 169. effected

of the

Pedestal or Pillow-block Bearings are used where it is necessary to have a bearing that is rigid and yet adjustable. Fig. 169 shows the ordinary form of pedestal bearing em-

ployed for supporting shafting from 3" to 8"

The

inner surfaces of the block

P and

suit the outer surface of the bushes.

cap

When

pared by hand-work to receive the bushes fitting strips

FS

to facilitate fitting, but

planing, the strips are unnecessary.

C

the block

it is

is

pre-

provided with

when prepared by engineers make

Some

the bushes that they do not touch each other is in position,

in diameter.

are formed to

when

the shaft

and as the bushes wear, a space being

left

be-

tween the cap and the pedestal, they are brought nearer together by screwing down the cap C by means of the bolts

C B.

To keep

the cap from being screwed

down too

far,

causing the bushes to bind the journal, the space between the

cap and the pedestal is sometimes filled with hard wood and the wear is taken up by filing down the hard-wood distance-

BRAKINGS, SOLE-PLATES,

AND WALL BOX-FRAMES. down

pieces, thus allowing the cap to be screwed

Others make the bushes

distance.

as in Fig. 169,

when

become worn they for the wear.

the bushes

are filed

When

fit

down

in contact

each other and no distance-piece

be provided with double nuts.

is

a limited

with each other,

the shaft, and sufficiently to

the bushes do not

231

come

when they compensate

in contact with,

used, the cap-bolts should

After the pedestal has been

FIG. 169.

adjusted to suit the shaft,

P B.

The

the bolts

it

is

held in position by the bolts

holes in the base- and sole-plate through which

PB

pass are

made oblong

to aljow the pedestal

be moved along the shaft or transversely to

To which

facilitate the fitting of the pedestal to the piece it

is

carried, the

base

is

to-

it.

upon

provided with fitting-strips

around the edges and across the centre.

The

oil-cup

is

usually

DRAWING AND DESIGNING.

232

cast with the cap C, or screwed into the tapped hole O, Fig.

On

169.

pedestals having journals less than 3" in diameter

O may

be made to receive an oil-cup with a J" pipe tapand when over 3", with a f" pipe tap-shank. shank,

Draw

Exercise 76.

a general

arrangement of a pedestal and sole-plate, Fig. 169, substituting the form of bearing

shown

in

164.

Fig.

Show

HALF ELEVATION and HALF

a

SECTIONAL ELEVATION, the plane the centre of the block

;

also a

of section passing

through

HALF PLAN and HALF SEC-

TIONAL PLAN, the plane of section passing transversely through the centre of the journal. From the elevation project a HALF END-ELEVATION and HALF SECTIONAL END-ELEVATION, the plane of section passing through the centre of the pedestal. Make the length of the holes through the sole-plate and pedestal-base sufficient to allow the pedestal to

Make

direction.

Construction.

terms of

D (the

D = 4"

and

L=

2D.

move J"

Scale half

either

in

size.

All parts dimensioned in decimals are in

diameter of the journal).

inches are constant.

Any

Parts

marked

in

parts not dimensioned can be de-

termined by the student from knowledge derived from previous exercises. A method of drawing the joggles^ is shown at

Fig.

169,

which

will

be readily

understood from the

drawing.

SELF-LUBRICATING PEDESTAL. In this design, Fig. 170, an

the under

oil

side of the bearing, in

reservoir

OR

is

formed on

which loose rings

R

arc

revolved by their friction on the journal, thereby raising a c ^ntinuous supply of oil to the upper side of the ber.nng,

keeping the journal thoroughly lubricated and

not

BEARINGS, SOLE-PLATES,

AND WALL

BOX-FRAMES. 233

DRAWING AND DESIGNING.

234

wasteful, as the surplus oil that flows out of the bearing is

chambers

in the

caught

CC

and carried back to the reservoir

OR,

As

the same

oil, in

repeatedly, after a time useless.

this it

form of lubricator,

being used

becomes dirty and thick and

removing the screws

By

is

5

the old

oil is

is

then

drained

off,

and the reservoir can then be replenished by pouring new oil These openings are made into the openings in the cover. can see

large, so that the engineer

This pedestal

designed for

if

the rings are revolving.

down

pressure,

and as there

wear on the upper bush it is cast with the The lower bush B is a separate piece, as shown by

be very

will

is

cap C.

little

To

the sketch, Fig. 171.

reduce the machining

vided with projecting faces

MS,

it

is

pro-

called

machining strips, upon corresponding projections on the pedestal,, and are made concentric with the shaft, so that to remove the which

bush

fit

it

when

not necessary to withdraw the shaft, as the bush

is

relieved from the load can be turned to the upper side

of the journal.

arrangement the pedestal is practically independent of wear, as the bushes can be removed and re-babbitted

By

with

this

little

trouble or expense.

To keep cast at each

the bush from moving laterally, flanges

end which

on the pedestal. The lower bush piece

DP, which

down too

far

is

also

fit

end machining

inside of the

F

are

strips

kept from turning by the distance

keeps the cap from being screwed

and -clamping the

shaft.

of the bushes, the distance pieces

cap go further into the pedestal.

To

DP are To

take up the wear

planed to

let

the

allow this, a space

AND WALL BOX-FRAMES.

BEARINGS, SOLE-PLATES,

A

is left

between the pedestal and the cover.

This space

need not be greater than the thickness of the babbitt " thick. which should be from f" to

The cap

is

made

to

fit

into

235

lining,

the pedestal so as to

sit

squarely upon the journal, and does not depend upon the

cap bolts to prevent

The cap

is

lateral

movement.

down by two

usually held

large bolts in the larger sizes of pedestals

The

practice to use four. in section,

and have

The

the pedestal.

T

but to avoid

bolts, it is

quite

made square

bolts in this case are

heads which

pedestal

is

common

into recesses cast in

fit

held in the proper position

by

the bolts PB, which pass through oblong holes in the pedestal to

allow

for

longitudinal

This form of pedestal

is

suitable

either

in

adjustment

for journals

direction.

from 5"

in

diameter up.

Length of Bearings. surface of the journal

The

to allow the heat to radiate as fast as will

the

converts the mechanical energy into

heat, and, unless the area of the journal

temperature

resistance at

frictional

become great enough

cant, allowing the rubbing surfaces to

is

sufficiently large

generated, the

it is

to destroy the lubri-

come

in

contact and

adhere to each other. The radiating surface would be enlarged by increasing the diameter of the journal, but the velocity of the rubbing surfaces would also be increased; therefore the

which ,o r.t

it

frictional

resistance "and

acts would be greater.

Thus

the it

space through

will

be seen that

add to the radiating surface without increasing the work the surface of the journal we must increase the length of

the bearing. In a paper read before the Manchester (England) Associa-

DRAWING AND DESIGNING.

236

tion of Engineers, Professor

is

stated that the area

be such that not more than one thermal

of a bearing should

unit of heat

Goodman

generated per square inch of bearing surface

per minute.

P

Let

total pressure in

pounds;

= coefficient of friction; = .S speed of circumference /t

minute

= --

of journal in

feet

per

TtDN 12

;

N'= number of revolutions per minute; A =

area of bearing in square inches, eter

WX

i.e.,

the diam-

the length L\

D = diameter of journal in inches; L = length of journal in inches;

W= width of the chord Foot-pounds

of

in contact, in inches.

work done per minute at the circumfer= PpS. The thermal units per minute

ence of the journal

P^SW A = 77 8)

and

With

j

steel

f

from which running

journals

in

L=

may

in

ju,

the coefficient of

be taken at .0056.

Exercise 77.

6"

in inches.

bronze or white-metal

bearings, having continuous lubrication, friction

^,

fDesjgn a^^^lubricating pedestal for a shaft

diameter, of the

>

^^wn

in

Fig. 170, to carry a

load of 35,000 pounds, ancFrun at a speed of 300 revolutions

per minute.

Show

a

HALF ELE.VATION, HALF-SECTIONAL ELEVATION,

the plane of section passing through the centre of one of the lubricators, a

HALF END ELEVATION and HALF TRANSVERSE

SECTION, the plane of section passing through the pede/.tal

HALF PLAN of the left-hand side of the pedesQUARTER PLAN with the cover (C) removed, a QUAR-

at the centre, a tal,

a

BEARINGS, SOLE-PLATES,

AND WALL BOX-FRAMES.

TER-SECTIONAL PLAN, the plane the centre of the shaft.

of section passing through

Scale 3" to the foot.

Make also full-size drawings of the lower bush, showing a HALF ELEVATION and HALF-SECTIONAL ELEVATION, a HALF END VIEW, and a HALF TRANSVERSE SECTION, and a plan and elevation

of the ring-joint as

shown.

All points are proportional to the diameter (D) of the journal, except those parts

of various sizes.

which are constant for journals

CHAPTER

VII.

BELT GEARING. Among

Belts for

the

belting are leather,

canvas,

bands,

camel-hair, flat

different kinds of material used

many

cotton, flat

catgut,

gutta-percha, India-rubber,

wire

or

hemp

steel

rope,

chains, etc.

The most common

general practice are leather and

in

cotton, the latter often found coated with India-rubber and

known

as

gum

Leather

is

belts.

more durable than gum under most conditions,

but for main driving the latter

which

is

is

superior, having an adhesion

claimed to be one third greater ihan the former.

Transmission of Motion by Belts.

Motion

may be

transmitted from one pulley to another with uniform linear velocity

by means

of a belt, provided there

the belt on the pulley;

every part of

it

will

i.e.,

no slipping of

is

regarding the belt as inextensible

have the same velocity as the outside

rim of the pulley. Referring to Fig. 171,

let

d and l

d^

be the diameter

driver and driven pulleys respectively, and let N^ and their revolutions per

The speed

minute and P'the velocity of the

ci

the

N

be

belt.

of the rim of the driver

=


* N,

= V

.

.

.

.

.

.

238

(i)

BEL7' GEARING.

B

FIG. 171.

and the speed

of the rim of the driven

=

d,

n N,

= V

(2)

therefore

d n N, t

=

d.

N,

or

rf.JV,

=

djft

or

=

.

(3)

ratio of belting questions concerning the velocity the pulley diameters should be taken to the centre of the belt

In

all

DRAWING AND DESIGNING.

240

thickness; thus the virtual diameter of the pulley would be

For

the nominal diameter plus one thickness of the belt.

other calculations the

may

The

much

be neglected without

Example there

thickness of

is

the belt

A

so small

it

error.

In the draughting-room at Sibley College

i.

a valve-motion model driven

shaft

is

motor

of the

by an

electric

i"

carries a pulley

motor.

diameter from

which passes a belt to a 15" pulley on a counter-shaft B. This shaft carries another pulley 6" in diameter connected by diameter on the

a belt to the driving-wheel pulley of 30'

valve-motion model axle.

The speed

of the

of the valve-motion

From formula

motor

model

(3)

we

N,_d

N~ t

Substituting

we

d,

1450 R. P. M.

is

in

Find the speed

R. P. M., Fig. 171.

get

d._

15

3

o_

6"

d,~^l

get

Some Practical

Rules.

The width

of

belts

should

be

about 25 per cent less than the face of the pulley. It has been demonstrated by experience that large pulleys and fast running belts are much more economical than small pulleys and slow-speed belts.

All pulleys should be carefully

centred and balanced on the shaft.

Driving-pulleys carrying

shifting-belts should have a perfectly flat surface.

pulleys should

when curved

have a convexity of

-J"

to

All other

12" of width;

the chord of the arc should be the same.

For

BELT GEARING.

241

pulleys smaller than 12" wide, from f" to J" per foot of width

should be used. Pulley diameters should be as large as can be used pro-

vided the belt speed

which

kept within 5000 feet per minute,

is

held to be the limit of speed for belt economy.

is

With regard

to the position of idle pulleys in relation to

the .driving-pulley Taylor

when

satisfactorily

says,

" Idle pulleys work most

located on the slack side of the belt about

one quarter away from the driving-pulley." Transmission of Power by Belts. Let two pulleys A and B be connected by a belt with a tension equal to 7,. Until force

at

A

A

applied at

is

7

pulleys, the tension

t

7!,

the rim of the pulley; the

slipping, == efa, or 7,

-f-

7

be equal; but as the force

By -f-

=

logarithms 7,

- fa

Example 1450 R. P.

2.

M

A

resistance to rotation at

when the

Where

e

is

is

at the point of

be a

maximum and

belt

7, will

the base of the Naperian

/is the coefficient of friction

a

in

we

log. e

= P ==

7, to

efa.

2

n measure and

i.e.,

of

ratio

system of logarithms,

7,

will

increases the tension in 7, will increase, and that in 7,

will decrease until 7,

in

tending to produce rotation of the

and 7,

=

degrees

find

X

that

=

.3,

a

is

0.0174. 7,

7,

=

efa

=

log.

.4343/^-

H.P. dynamo is to have a speed of and has a 6" pulley on its shaft. Power is obsix

tained from an engine fly-wheel running at 58 revolutions per

minute.

To

obtain the required velocity ratio between the

engine and dynamo, the diameter of the fly-wheel to be 25 times that of the

tion it

;

will

dynamo

will

have

pulley with direct connec-

but such a diameter would be practically impossible, so

be necessary to

install a counter-shaft.

Let 18" be the

DRAWING AND DESIGNING.

242

most suitable diameter

for the largest pulley

on the counter-

shaft, then the necessary speed of the counter-shaft will

=

1450

=

X 1

8

483 R.

P.

M.

be

Between the engine and

=

counter-shaft the pulley diameter ratio

8.32.

Let

58

the diameter of the fly-wheel be 50" then

pulley on the counter-shaft will be 8.32

.

To

determine the

dynamo with

J

1

of

,

=

size

connecting-

6" nearly.

of belt necessary to connect

the counter-shaft

to the

=

its

we

will

the

have to find the value

working pull on the lower side of the

belt.

FIG. 172.

First

find

198,000

foot-lbs. per

6x runs at

the work done by the

X

shaft

6

X

33,ooo

minute; the rim of the dynamo pulley

1450

198000

dynamo

=

= 87

2277 Ibs.

and counter-shaft be

feet

per

minute;

therefore

Let the centres of the dynamo

15 feet apart, then (see Fig. 172)

BELT GEARING.

=R

tan.

trig,

a

=

I

functions

0.0174

we

20

180

=

V=

Q" <-

T -

/

3.05.

oO

and from a table of natural

.04,

=

find that tan. .04

=

a

175.75,

Then

log.

7\

in

+

2.25.

number

=

n measure

T,

=

.3974; from a table of logarithms we log. of the

243

.4343 find

X

.3

175.75

X

X

=

that .3974

3.05

the

is

2.50, therefore

T^

7;

=

2.50.

Combining these equations thus: 2.50 T,

-

1.50 j;

allowing 70

Ibs.

2.

so

87

a

217.5,

we

X

find

2.5",

217.5

- 2. so T, = o,

T, -5-

=

1-50

J

ar"i

45>

per inch width of belt, then 145

Some

r =

-T-

70

=

2.06, say 2j".

Practical Rules for the Transmission of Power.

Richards gives the following rule for the size of driving-belts, which he says is near enough for all cases that arise in ordinary practice.

H.P.=^. Where

V=

.

...

.

(4)

the velocity of the belt in feet per minute.

W=

the width of the belt in feet.

A =

the area given to suit different conditions in the following table

TABLE LEATHER BELTS SINGLE THICKNESS. i

On smooth iron pulleys On wooden pulleys On covered pulleys

:

;

30.

-"

GUM BELTS AVERAGE THICKNESS.

H. P

80 65 50

ft. ft.

ft.

i

On smooth On wooden On covered

H.P.

iron pulleys pulleys.

60

ft.

50

ft.

pulleys

35

ft.

DRAWING AND DESIGNING.

244

Belts should be

made

as

wide as possible

they are often

;

too narrow, but never too wide.

Thickness of

Belts.

As

belts

increase

in

width their

thickness should also increase.

Double

on pulleys over 12" diameter.

Large belts running at very have slots punched

belts should be used

high speeds, as in electrical work, should

through them

in

such manner and position as to prevent air

cushion.

The

following proportions for thickness of belt and cor-

responding working tension, based on a safe working stress of

320

Ibs.

per sq.

in. for

laced joints, are given

TABLE

31.

by Unwin

:

BELT GEARING.

245

246

DRAWING AND DESIGNING.

BELT GEARING-

d = l

diameter of set-screw

247

in solid pulley

=

\d

+ iV'-

(6)

= diam. of bolt in split pulley at rim and hub = eq. d^ = set- screw for key = .2$d. d^ D = diameter of pulley. E = centre of rim bolt from inside of rim = d^ + t -f i"

(6)

(7)

t

V

f =

radius at end of arms

g

width of arm at rim

h

-

width of arm

=-

=

\Ii.

at centre of pulley

BD

8

6 337A/~

sin g le belt

-

(Unwin.) .

.798

n

= = =

p

=

k /

v

thickness of

-

by

2

of

=

arm

length of hub

number

=

arms

=

to B. ^

+ 4.

The

thickness of rib surrounding

/,

thickness of rim

w=

.

nearest

see Table 31.

=

.6/

+

inside taper of pulley rim .

thickness of

hub

hub between arms

14

-

/,

-r-

2.

VlBD

+

i for single

\

radius of pulley crown

Exercise 84.

A

=

from

=

.31 d.

....

OO 5 D-

=

fi-'t

R =

number divisible

should be taken.

thickness of belt

=

h -

%B

t

/,

(8)

/BD

double

.

belt.

"

(9)

(10)

(u)

3 to 5 b.

fan revolving with a speed of 1800 rev.

on its shaft. per min. develops 8 H.P. and has an 8" pulley Power is obtained from an engine fly-wheel running at 75

=

Determine the Diam. of fly-wheel 5 feet. per min. proper diameters of the intermediate pulleys and make a suitrev.

DRAWING AND DESIGNING.

248

able working drawing of the largest of them, similar to Fig. Scale 6"

173 or Fig. 174.

See Example

I foot.

241.

2, p.

Wood-split Pulley

(Fig.

The Committee on

175).

the Franklin Institute,

Science and the Arts of

in

report

ing on the Dodge Wood-split Pulley with wooden bushings, stated that in most cases wood-split pulleys are better than iron pulleys. (1)

on the (2)

Some

They

of the reasons given for this are as follows

are lighter than iron pulleys, lessening the weight

and bearings and reducing

line shaft

The compression

iron or steel shafts with

on the shaft quite (3)

The

friction.

wooden pulley on

fastening of the

wooden bushings

will

hold the pulley

firmly, dispensing with the use of keys.

grip of a belt

on a wooden pulley exceeds that on

an iron pulley to an amount equal to (4)

The method

at least 33 per cent.

wooden pulley

of fastening the

shaft neither mars nor

weakens the

shaft,

of poplar.

The two

air-dried,

then

shafts

are

the case

halves of the pulley

The bushings

are secured to the shaft with bolts. different-sized

is

segments, the

They

made

to the

and prevents any

tendency to throw the pulley out of balance, as when keys and set-screws are used. " are built of wooden Construction. face being

:

made

bored and

of

to

fit

hard wood, thoroughly

kiln-dried

;

then each bush

is

counterbored to exact size of shaft, then carefully turned on the outside to fit the bore of the pulley. They are then cut transversely in halves."

Make complete working drawings of

Exercise 85. split loose pulley

be the same

as

14" diam., shaft 2" diam.

shown

in Fig.

175.

Scale 9"

a

wooden

Projections to

=

i foot.

BELT GEARING.

249

DRAWING AND DESIGNING.

250

All-wrought-steel factured

Pulley.

by the Am. Pulley Co.

This is

as

pulley

shown

in Fig.

176.

manuIn a

paper on the subject by Mr. E. G. Budd before the Franklin Institute in June 1897, the following advantages are claimed for the all wrought- steel pulley: (1)

They can be used

in

the heaviest service, clamped to

the shaft without keys or set-screws, and never show a sign of slipping. (2)

There

is

no machining required.

The

rims and arms

FIG. 176.

are cut with shears pressure.

and pressed into shape with hydraulic

BELT GEARING. Economy

(3)

of material

2$ I

and symmetry of form, requiring

no counterbalance. (4) it

is

Being

fully as

made

of

light

as

the

the

and strongest material, pulley, and much more

best

wood

durable. Construction.

the rim

is

Referring to Fig. 176

made up

of four segments.

The rim edges

It

means

rim at the centre of the face give a

be seen that

may

The

transversely and once longitudinally.

the arms.

it

is

divided once

on the

flanges

of fastening

to

it

are rolled, giving a neat appearance

and preventing the scraping of the

belt in

throwing

it

off

or

and

is

on.

The hub

made

is

of half cylinders of

heavy

steel,

connected to the rim by a spider divided into four parts, two

The

parts to each half of the pulley.

spider arms are

flat

and have the edges lying in the direction of rotation. The manner of fastening the arms to the hub and rim, and their

A

make them

ex-

a true working drawing of the

all-

corrugated section, as shown at

in Fig. 177,

ceptionally strong for their purpose.

Make

Exercise 86.

pulley shown in Fig.

wrought-steel given.

Scale

= 4."

Cone-pulleys

177 to the dimensions

/ foot.

In operating machine

necessary to change power and speed.

tools

This

is

it

is

often

accomplished

by means of cone-pulleys. The driven pulley has a series of steps whose diameters are proportioned so that the belt shall fit all pairs of steps with an equal tension, and most

when

easily

the belt

is

shifted from one pair of steps to another

the velocity ratio will be changed.

252

DRAWING AND DESIGNING.

BELT GEARING. Length of Belts

L =

Let

D= d= /= .

U

2$ 3

(Fig. 178).

length of belt;

diam. of large pulley; diam. of small pulley; distance becween centres of pulleys:

= angle whose

sine

D-d for 2l

=

open

FIG.

-.

fo-r

crossed belts and

belts.

178.

a table of sines find the angle 6 in degrees and

From COS0.

Then

for a crossed belt:

.

and

for an

(12)

jpen belt 7f

L = -(D +

d)

+ B(D - d) + 2l cos

('3,

DRAWING AND DESIGNING.

2 54

The

length of the crossed belt

/ are constant

is

constant

D+d and

when

therefore in designing a pair of cone-pulleys so that the crossed belt will have equal tension on all it is ;

pairs,

only necessary to use a pair of equal and similar cones tapering opposite ways.

To

a

design

AAAA

Let

of

pair

and

cone-pulleys

d.d^d^

leys (Fig. 179).

And

Mr. C. A. Smith

in the

=

diameters

of

S.

M.

suppose the following data to be

open

beltr

opposite

pul-

method given by

using the graphical

A.

an

for

E., vol. 10, p. 296, let us

known

:

Diameters of D.D^D.D^ and d,. /= distance between centres.

(1)

(2)

Then

let

C and l

be required to find the diameters of

c are the centres of the

Around draw d

it

centre

C draw

d& and d^

opposite cones.

circles

AAAA

and

at centre c

to the diameters given.

Draw tangent A^i

E and erect a perpendicular EF. EF = .314! found by experiment.

Bisect Cc in the point

Make the distance With centTe F draw arc tangent to arc

A

will

A

be a

All lines drawn

tangent to Z>X-

common

tangent to a pair of cone

steps giving the same belt-length as that of the given pair.

So

to find the diameters of the steps d^d^

and

necessary to draw tangents to D^ and arc A,

A and

arc

A, and with centre

c

and

radii =

d<

it

A and cd^

,

is

only

arc

cd and z

A

y

cd^

This respectively, draw the circles of the required steps. method is an approximation, but close enough for all practical purposes. Exercise 87 eters

A=

18",

Referring to Fig. 179: First, assume diam-

A=

14",

A = 10" and A and

d,

= 6",

and

BELT GEARING.

255

find the corresponding diameters of the opposite steps accord-

ing to Smith's graphical

method

just explained in connection

with Fig. 179.

Second, make complete working drawings of one of the cone-pulleys, showing half longitudinal cross-section and half side elevation

Fig.

1

combined, and also a half end elevation

Scale 6"

80.

=

like

i foot.

PROPORTIONS OF CONE PULLEY. Let

= thickness of edge of rim = a-, h = thickness of hub = 14 V'BD + J" from eq. /

.

H length of hub = R = ^ce radius = B.

1

l

(10)

.

f

The remaining dimensions may be ing table.

TABLE (Dimensions

b

32.

in inches.)

taken from the follow

;

2 S6

DRAWING AND DESIGNING.

BELT GEARING.

FOLLOWER FIG. 180.

257

DRAWING AND DESIGNING.

258

rope pulley measured to the centre of the rope should not be less

than that given by the following rule

D = (loD + l

D

1

=. the smallest

D = the As

1

6)

A

:

where

diameter of the pulley;

diameter of the rope.

in the case of belt gearing, the slack side of the

rope should be on top wherever possible, so as to increase the arc

between the rope and the pulley. This is the form of groove long used Fig. 181.

of contact

Britain.

to

It

has

Great

in

sides inclined to each other at from 45

flat

60.

The

general practice in America

groove shown

in Fig.

than

it

does

making

it

last

the

longer

the flat-sided groove.

Exercise 88.

Make

a drawing of the section of the rim of

a rope pulley with five grooves, as of rope to be if".

Scale full

shown

in

Fig. 181.

Diam.

size.

Take the other dimensions from the following

TABLE

33.

(Dimensions in inches.)

D

This

in the groove, distributing

entire surface of the rope,

in

to use the form of

182, where the sides are curved.

form allows the rope to rotate

wear over the

is

table.

BEL 7 GEARING.

*- G

>j

DKA WING AND DESIGNING.

BELT GEARING. Make a drawing of 182. Diam of rope

Exercise 89.

shown

in Fig.

Remaining dimensions

may

(Dimensions

D

the rope pulley rim section

to be ij" Scale full be taken from Table 34.

TABLE

26 1

34.

in inches.)

size.

CHAPTER

VIII.

TOOTHED GEARING. PROPORTIONS OF IRON TEETH.

Fig. 183.

= k VP\ = circular pitch p' = diametral pitch (p X /) = 3- 1416; = T -- p' D = pitch diameter = D X/ T = number of teeth = .3/; / = addendum of tooth = .35^ to .4^; /' = flank of tooth = = / thickness of tooth .48^ for cast-iron teeth, = .5/ for cut teeth; k = .04 for hand-wheels, = .05 for ordinary mill gears, = .06 for wheels of high velocity and mortise gearing; P = the total force transmitted by one wheel to another /

\

;

through a corner of the tooth

V=

X

63020^-^.;

.

12

R

y

the velocity of the pitch line in feet per second 2

N H

=

X

=

60

-00873^;

the radius of the pitch circle in inches;

the

number

of revolutions of the wheel per

minute;

the horse-power transmitted by the wheel. 262

TOOTHED GEARING.

WOOD TEETH

or cogs for mortise wheels are usually

thicker than for the iron teeth of the meshing wheel, t'

=

thickness of iron teeth to

/

=

thickness of

Exercise 90.

gear of

15

=

wood cog

teeth

and

Draw

.6/.

rack, p'

Involute system, angle of action

,;

mesh with mortise wheel

To construct the

(Fig. 183.)

jg

made

or

teeth

for a spur

diametral pitch

=

2.5.1.

=15.

the centre line C, and compute the diameter of the

by dividing the number of teeth by/'. At the point a where the pitch circle cuts C draw

pitch circle

making an angle of 15 with the horizontal pitch draw the base circle tangent to L.

FIG.

To

find /: will

quotient

may

be laid

Divide 360

by the number

with a protractor.

Or

in

:

and

of teeth:

the

the arc/, which

divide the

inches in the circumference of the pitch circle of teeth

line,

183.

be the number of degrees off

L,

line

the quotient will be the pitch.

number

of

by the number

Or divide

a

quadrant

DRAWING AND DESIGNING.

264

of the pitch circle with the hair-spring divider into 15 equal

and from the point a mark every fourth division for the point where the outline of a tooth intersects the pitch

parts,

Next

circle.

lay off the thickness of the tooth equal to half

the pitch on the pitch circle of the wheel and the pitch line of the rack.

Draw

The

dum

addendum

the

root line of the rack

line

of

line

is

the wheel

drawn tangent to the adden-

and the root

of the wheel,

with a radius

of the wheel is

line

tangent to the addendum line of the rack. To describe the involute curve of the wheel-tooth: Take a piece of tracing-paper or thin celluloid, and trace upon

it

the

and make a small puncture at the point a with Now at the point where line L is tangent to the

straight line L,

a needle.

base line stick a needle, and rotate line clockwise until

it

intersects the base line;

L

about

base line at the second needle in the tracing, with a

mark

4H

;

counter-

at the point of in-

tersection stick another needle, and, removing the

adjust the tracing until the line

it

L becomes

first

needle,

tangent to the

then through the puncture a

pencil sharpened to a conical point

a point on the drawing-paper: this will be a point on

Continue to

the curve.

number has been found It

will

be seen

forming the

find similar points until a sufficient

to form the

by the

addendum

figure

addendum

of the tooth extends

line to the base line; this part of the curve

similar

way

generating

to the part line

L must

above the pitch be rotated

in

of the tooth.

that the involute curve

line,

below the pitch

is

generated

in

a

except that the

the opposite direction.

TOOTHED GEARING. The addendum

lines

26 5

of the other teeth

may be

traced

from the one just found.

The rim be

less

of the rack, according to

than d

in

thickness,

=

.^.p -f-

Reuleaux, should not .125.

Unwin

gives

Low & Bevis give -47/. Use Unwin's proportion. When the curves have been carefully pencilled as above,

.48/1

they

may

be inked

in

with arcs of circles computed by means

following odontograph table, taken from Geo. " Handbook on the Teeth of Gears" Grant's of

the

:

ODONTOGRAPH TABLE INVOLUTE TEETH. CORRECTED FOR INTERFERENCE, INTERCHANGEABLE

Teeth.

SET.

B.

DRAWING AND DESIGNING.

266

For any intermediate number

of

teeth

proportionally

intermediate values can easily be found by calculation.

A

Example.

number the

of teeth in the table

number

=

radius

The with a

A

to be divided

whose radius

special

to line

is

by/

31

;

=

then

7

(1.25),

5.06,

making the true

face

4^" nearly.

flank of the tooth

fillet

and one

gear-wheel has 30 teeth, and the nearest

rule

is

;

radial,

and

it is

joined to the rim.

equal to the clearance.

provided for the rack-teeth: the flank

a straight line drawn at right anglesthe other half of the face is a circular-arc centre

half .the face

L

is

is

is

on the pitch line and a radius found by dividing 2.10" by/'. This rounding of the point of the rack-tooth is necessary

when

it is

The ing the

to

mesh with

a pinion having less than

28

teeth.

following tables will be found convenient for compar-

diametral

pitch with

the

from Grant's "Teeth of Gears": Cir.

Pitch.

circular pitch

;

they are

TOOTHED GEARING. Exercise 91.

spur-gear wheel 12 teeth.

/'

=

(Fig.

184.)

and pinion 2.10.

;

267

To construct the

for a wheel to have 40 and the pinion teeth

Walker system, non-interchangeable.

FIG. 184.

The

curves of the teeth are epicycloids and epitrochoids,

and are found by rolling the pitch circles on each other follows: For the addendum of the wheel-teeth draw arc on a piece of tracing-paper or celluloid, and place

as.

A

over the-

it

drawing tangent to arc B at the point a. Through the point a on the celluloid make a puncture with a needle, and while

holding the needle at a rotate the celluloid a small'

distance to the right until arc

A

intersects arc B.

At the

point of intersection place another needle, and, removing the first

needle, adjust the celluloid so as to

B

to arc

mark

a

at

the second

way

For the

A

arc

tangent

needle, and through the puncture

point with the pencil

curve of the face edge. similar

make

;

this will

Other points

be a point

maybe

in

found

the in a

to complete the curves required.

face edge of the pinion-tooth roll arc

and the point a

will describe the

curve ab.

B

on arc A*

DRAWING AND DESIGNING.

268

To draw the celluloid celluloid

the

The

lett

the flank of the wheel-tooth: is

tangent to arc

B

b\

then

A

on

on the

roll arc

A

to

will describe the flank of the tooth.

flank of the pinion-tooth

on arc A, when the point

arc

at a, trace curve ab

and make a puncture through

on 8, and point b

When

is

b' will

then found by rolling arc describe the curve.

B

TOO 7 HED GEARING. Exercise 92.

(Fig.

Draw

185.)

the

269

HALF ELEVATION,

HALF PLAN, and HALF SKCTIONAL PLAN of a spur-gear wheel and pinion ; the wheel to have 60 and the pinion 15 teeth.

/=

2.5-

Draw

all

involute

the

system.

teeth

in

Fig

185

one quadrant of the elevation, the drawing of

is

wheel 'made by Messrs. Robert Poole

Md., and presented to Sibley College

&

a spur-gear

Sons of Baltimore,

for use as

a model

in

the drafting-room.

Draw ELEVATION,

CROSS-SEC-

TION, and PLAN of a bevel-gear wheel and pinion.

The axes

Exercise 93.

(Fig. 186.)

are to be at right angles to each other, and the wheel

have 50 and the pinion 24 teeth,

p'

=

is

to

Radial flank

2.10.

system, non-interchangeable.

Draw

centre lines

C and

C' at right angles to each other,

find the radii of the pitch circles,

proper

distance

from the axes.

and draw

Draw

E

D and

D'

and E'

at the

at right

F

and F' are the developed pitch on which the teeth are drawn, the same as if they were to

angles circles

each

for spur gears.

A

circles

and

B

other.

And

since the flanks are radial, the rolling

used to generate the face curves of the teeth

are equal in diameter to the radius

R

and R' of the developed

pitch circles of the pinion and wheel respectively.

A

model

of this

wheel

will

be found

in the

drafting-room

for use in connection with this problem.

Exercise 94.

worm ; drawn will

(Fig.

187.)

Construct a worm-wheel

and

the wheel to have 50 teeth, and the worm-teeth to be like those of the involute rack

;

that

is.

be drawn at right angles to line L, when

the face edge line

L makes

DRAWING AND DESIGNING.

2/0 the angle of 15

with the horizontal pitch line H, as shown

by the longitudinal

The

cross-section in Fig. 187.

teeth of the wheel are

made by

a cutter similar to

the worm, except that grooves are cut in the threads parallel to the axis, itself is

wrought

and the material

usually

made

is

hardened

of cast iron,

iron or malleable cast iron.

but

is

steel.

The worm

sometimes made

of

TOOTHED GEARING. The

271

horizontal pitch line should be so placed as to bisect

the cross-sectional area of the wheel-tooth at a\ the proportions of the teeth for

may be

otherwise

the same as those used

wheel and rack.

FIG. 187.

Design a cast-iron gear-wheel given the pitch-circle diameter 51", revolutions per minute 90, Exercise 95.

(Fig. 188.)

horse-power transmitted 280. First find the

= P=

:L

jr~i

(

whole pressure of one wheel on the other

find the circular pitch

The number

=

v =p

=

:

_

X

25.5

X

90

then

.0447

of teeth can

the diameter of the pitch circle

p __

.00873

now be found by multiplying

DX

3.

1416, and dividing by

t^e nearest even number.

DRAWING AND DESIGNING.

FIG. 188.

Let

T

represent the

of the pitch line

may be

number

of teeth

;

then the velocity

expressed as follows:

pTN X

12

and the pressure on the teeth

550

X

12

X

pTN

60

1

6'

is

X

H- =

H 396000

TOO-THED GEARING. Taking the width

= = = h = t

of the teeth into consideration, let

when worn, wood teeth when worn

.$6p for iron teeth .45/ for

.6p for

wood

=

and

teeth; then

.O46#//for iron teeth,

.o84#//for wood teeth;

= ^\/5 ^ ^ w ^ en ^ = width

=

of tooth

from 2 to 4/,

in practice

ki

When

b

=

= .0707 = .0848

2.5/,

The dimensions

for iron wheels, for mortise wheels.

Unwin gives/

Low & of

Bevis give/

the teeth

the proportions already given

=

;

.Jp for iron teeth,

P=

and /

2?$

:

=

.0447

VP

= \f ^r.

may be determined from b

=

the

breadth of face

2.5/, etc.

As

the shaft for this wheel would probably have to resist

a combined twisting and bending action, we can assume the diameter of the shaft to be 6", and the wheel fit 7".

The width and rim,

breadth of the arms, the thickness of the

and the thickness and length

easily

pages.

of the hub, etc.,

determined by the proportions given

in

can be

the following

DRAWING AND DESIGNING.

274

Arms

Gear Wheels. The shown in Figs. 189 to

sections are

arm

usual shapes of

of

189

cross-

is

mostly used for pulleys and light wheels; Fig, 192.

Fig.

shows another section that

191

monly used

com-

spur wheels, that

in

192 for heavy spur gears, and that

Fig.

189 for bevel gears.

in Fig.

When the

in light

is

=

a

=

.

Unwin

teeth,

the

gives

thickness 7

=

//

Vn

measured

at

the

Taper J"

in

12" on each side

the rim.

n

=

the

centre

VbR,

the wheel.

of

number

toward

R=

of arms;

the radius of the wheel; b

of

__

58

=

the width

of the cross-feathers, which

may be

the breadth of the teeth as

shown

in Fig. 193,

measured

or

f-

=

at b

the breadth of the teeth

at the centre of the shaft

and

from f to |f at the rim.

The ribs or feathers much to the resistance bending

in

B

do not add

of

the arms to

the direction of the driving

force, but they are necessary to give lateral stiffness to the

Unwin

arms.

gives

B

tapered to facilitate the

.3^).

The

feathers

should

be

removal of the pattern from the

sand.

To

determine the number of arms

give -^ taken.

+ 4.

The

nearest

number

in a wheel,

divisible

Low &

by

2

Bevis

should be

TOOTHED GEA KING. Unwin

gives

four

arms

for

275

wheels not over 4

diameter, six arms for wheels of from 4 to 8

and eight arms for wheels from

Rims shown is

of

Gear Wheels.

in Figs.

193 to 204.

used

in light

8 to

1

edge

=

on the subject: .48^

.

ft.

in

ft.

in

in

diameter,

diameter.

The usual rim sections The section shown in Fig.

are

193

wheels.

commonly The following proportions agree

thorities

6

ft.

d=

The other

closely with

most au-

the thickness of the rim at the are

proportions

shown

in

the

figures.

In the rims for bevel gears shown in Figs. 198 to 2OO

the thickest part of the rim should be %d. Figs.

20 1 and 202 show examples of mortise gears for

FIG. 198.

FIG. 197.

FIG. 199.

spur and bevel wheels respectively; fixed either

round given

iron in

by wood keys pins as shown

the mortise teeth are

as

shown

in

Fig. 202.

in

Fig.

201,

or

by

The proportions

the figures agree closely with good practice.

DRAWING AND DESIGNING. Shrouding. When the rim of a wheel is wider than the teeth and extends towards the point so. as to form an annular ring uniting the ends of the teeth, the teeth are said to be

shrouded.

Figs. 203

and 204 give two examples

By shrouding out

teeth.

to the

of

pitch circle as

shrouded

shown

in

Fig. 203, teeth which are no thicker at the root than at the

pitch circle can be strengthened about 100 per cent.

pinion of a pair of gear wheels the shrouding

In the

may extend

to

the points of the teeth as shown in Fig. 204; this compensates for the

weak form

of the teeth in very small wheels,

and

prevents their failure from excessive wear. FIG. 201.

FIG. 200.

-f-

FIG. 203

Hubs examples

shown

Gear Wheels.

of of

FIG. 204.

and 207 give the examples of arms

Figs. 205, 206,

hubs to correspond to 189, 191, and 192, respectively.

in Figs.

The

thickness of metal surrounding the bore of a gear

TOOTHED GEARING.

277

=w=

.4^ -f- .4" (when h = the width of the arm measured at the centre of the wheel). The keyway should be cut the full length of the hub, and the

wheel

metal

is

given by Reuleaux

reinforced

over the

keyway

if

the

wheel

is

in-

In large wheels the hubs are tended for heavy duty. sometknes strengthened by wrought-iron rings shrunk on

both ends; the thickness

made

is

the metal under the rings

=W b

is

=

,

and the thickness

width of teeth.

FIG. 207.

FIG. 206.

FIG. 205.

In heavy wheels with a large ing the bore, the

hub

the arms to give

relief

is

amount

of metal surround-

sometimes slotted across between

from

initial strains

contraction in cooling; these slots are then strips,

of

and the divided hub

is

due filled

to

unequal

with metal

held firmly together by the iron

or steel ring referred to above.

CHAPTER VALVES, COCKS,

A

Valves. fluid

valve

is

IX.

AND

OIL-CUPS.

a device for regulating the flow of a

through an opening.

Prof.

Unwin

divides valves into three classes:

valves, or those

which open with a hinge;

those which

perpendicularly to the seat;

rise

or those which

move

The

parallel to seat.

part of the valve in contact with its seat

Foot-valve and Strainer.

Flap-

(i)

(2) lift-valves, or (3) slide-valves,

valve-face

when

is

that

closed.

Foot-valves are used to hold

the water in long suction-pipes; otherwise the

pump would

have to be charged every time before starting. The strainer protects the valve from being choked with stones or other

made of two

solids.

The most common

foot-valves are

cast-iron boxes, called the valve-box

and

strainer,

bolted together by flanges, and having a leather clack-valve

between them.

The lower box

holes J" to \" diameter, and piece.

is

is

perforated with circular

called the strainer or snore-

In small foot-valves the suction

is

generally screwed

into the top of the valve-box.

Fig. 207 shows a vertical section and three half plans of a

foot-valve for a 9" suction-pipe. strainer,

A

is

the valve-seat,

B

VB

main

is

the valve-box,

valve,

and

C

5

the

an auxiliary 2/8

VALVES, COCKS,

AND

FIG. 207.

OIL-CUPS.

2 79

DRAWING AND DESIGNING.

280

This style of clack

valve on top of B.

is

called a relief or

Mr. Henry Teague, of Lincoln, England,

break clack.

in

a

paper read before the Inst. of M. E. of England, in 1887, reported having used a 15" main clack with a 5" supple-

mentary clack for the purpose of reducing the very great concussion which was had by using the 15" clack alone, with the result that even when the hand or the ear was placed on the clack-box hardly a tremor or a sound was perceptible.

D is

the entrance to the suction-pipe.

This double-valve feature gives almost complete freedom

from shocks even

in large

pumps, and therefore works very

quietly.

The main

valve,

made

of

J" leather, forms the joint be-

tween the valve-box and the strainer.

E

is

the top and

F

is

the bottom valve-plate, riveted together with f-inch rivets,

and an opening

equal to an area of about one

one third that of the main opening.

half or

opening It

in the centre

is

fitted

an

has

with the clack-valve

upper and a

with the bolt

H

C

This auxiliary

referred to above.

lower valve-plate, held together

and fastened to the main valve with two

screws at X, in plan and sectional elevation.

The

laps

L

should be

made one tenth

of the diameter of

the respective valve-openings. Exercise 96.

shown

in Fig.

box and

Make drawings

of foot- valve

and strainer

207, and also an outside elevation of the valve-

strainer.

Scale

3"

=

i foot.

This valve (Fig. 208) consists of an india-rubber disk D, a brass grating or seat s, and a perfoIndia-rubber Valve.

rated brass guard.

The rubber guard and

to the grating by a stud-bolt B.

valve are attached

The purpose

of the guard

VALVES, COCKS,

<

AND

j

FIG. 208.

OIL-CUPS.

251

282

DRAWING AND DESIGNING.

FTG. 200.

VALVES, COCKS, is

in

AND

OIL-CUPS.

The

to prevent the valve from rising too high.

the grating should

such that when the valve

The i.e.,

Ibs.

perforations

not be large enough to cause

The

flexure of the rubber disk.

ceed 40

283

is

much

area of the grating should be

closed the pressure does not ex-

per square inch.

thickness of the india-rubber disk for large valves

valves over 6" in

diameter

in

condensers and

pumps

India-rubber valves are not good for

should be f" to f ".

pressures over 100 Ibs. per square inch.

Exercise 97.

shown

valve as

Make

a complete drawing of the india-rubber

in Fig. 208.

Scale full size.

of the perforations in the conical guard

The

is

The

shown

projection

in Fig. 209.

Use

following proportions represent good practice.

the nearest TV".

Unit =

.19 \/^~

= diameter of india rubber disk =15.5 of unit. " b = thickness of the india-rubber disk = 1.6 " =: c = thickness of the grating-lip 1.75 d= diameter of the valve. = 2.75 " e = depth of seat-body a

/= diameter of

=

stud-body

g

diameter of stud

= k =

diameter of holding-down bolt

h

I =.

= = = = = =

depth of grating thickness of grating-rib

m = width of seat-lip n = diameter of guard Exercise 98.-

Make

2.75 1.75 1.25

2.50 .65 .75

12.00

"

" " lc

" " "

a complete drawing of an india-rubber

disk-valve similar to Fig. 208.

d

io

/r .

Scale 9"

=

I foot.

284

DRA WING AND DESIGNING.

FIG. 210.

VALVES, COCKS, Lift-

AND

OIL-CUPS.

These valves are usu-

or Wing-valves (Fig. 210).

ally

made

and

seat.

The

of brass.

essential' features are a circular disk

The edges between

the disk and seat are bevelled

45, and are easily

to the angle of

and ground together.

fitted

Springs or rods are used to close these valves sary to place

them

new

wings are curved arbitrary, and

slightly, as

The is

shown

when

To

in a horizontal position.

a partial rotation and provide a

it is

neces-

give the valve

seating at each stroke the

at Fig. 21

The curving

1.

be projected as shown

may

is

28$

in

the figure.

outside of the seat has usually a taper of J" in 12"', but

sometimes driven

the valve

straight.

.

The amount

of

the

lift

of

be determined as follows:

may

Let

= d = L=

lift

a

.7854^' and

a

area of opening in seat

diameter of opening

;

in seat;

of valve.

Then

Taking a

unit of proportion

=

L=

.....

.35^.

(l)

.2 4/

= thickness of disk = 1.3 / = length of wings = 8 at t = thickness of seat =

;

;

I

Exercise 99.

Draw

shown

shown

in Fig.

210 to the

Scale full size.

dimensions given. Exercise 100.

the valve as

small end.

Make drawing

in Fig. 211.

of the curved wing-valve as

Scale full size.

These valves are guided cenSpindle-valves (Fig. 212). and bridge otherwise they .are trally by means of a spindle ;

286

DRAWING AND DESIGNING.

\

*

\

VALVES, COCKS,

AND

FIG. 212.

OIL-CUPS.

28;

DRAWING AND DESIGNING.

288

work

similar to the wing-valve, but used for light

The wing-valve and a

and a leather face and

seat

flat

the spindle-valve are sometimes

in

pumps.

made with

also used for light

duty

in

pumps, but have no advantage over the bevelled metal edges. Let W(Fig.2 io) = the width of the bearing-edges measured perpendicularly to the axis of the valve,

p

= the maximum

ference of pressure on the two sides of the valve

;

then

dif-

~r =

nd yy

r

the crushing pressure per square inch on the narrow bevelled

edges of the valve and

The

greatest safe pressure per square inch for phosphor-

bronze

1000

for gun-metal, 2000 3000 Ibs. and leather and india-rubber, 700

is

Ibs.

;

;

Exercise 101.

shown

seat.

in

F

i

(

.

Make drawings

212.

Ibs.

;

cast

iron,

Ibs.

of the spindle

and valve as

Scale full size.

Ball-valves (Fig. 213).

These valves are much used

in

deep well-pumps and small fast-running pumps. To guide the lift of the ball it is surrounded by a cage with three or

The

be as narrow as safety will permit, so as not to interfere with the free flow of the fluid above four ribs.

the valve-seat.

To

lighten

The

ribs should

Gun-metal

is

the best material for the balls.

them they should be made hollow.

usual

for

proportions

the

ball-valves

are

given

below:

Unit

=

.2

Vd.

= 1.34^. = diameter of ball b = inside diameter of seat-casing = \.\2d. = .9 times c = thickness of ball-guide = e distance between guides ss^-f-^.".

a

unit.

VALVES, COCKS,

.

AND

FIG. 213.

OIL-CUPS.

289

DRAWING AND DESIGNING.

= = =

f= length of seat-shank g=

thickness of seat-flange

h

times unit,

3 i

1.2

k

= / =

I

lift

of valve

= 1.2

thickness of ball-shell

These valves work best with a small says that the

lift

Make drawings

Exercise 102. Fig. 213.

d

lift.

William M. Barr

of ball-valves should not exceed J".

\y

.

similar to those

shown

in

Scale i% full size.

Fig. 2 14 shows an ordi-

Flat India-rubber Disk-valves. of valve

nary example of this style valve-seat and spindle are cast

in

for cold

one piece.

water.

The

The

spindle

is

turned and polished, and the hole in the india-rubber disk is This allows free larger than the diameter of the spindle. T

V

action of the valve.

The

valve-seat

a pitch of eight threads to the inch, for all sizes

up

to 4^'' diameter.

is

screwed into place with

which

Mr.

maybe maintained W. M; Barr gives the

following dimensions for india-rubber valves:

TABLE Diameter.

35.

VALVES, COCKS,

AND

29 1

OIL-CUPS.

1 FIG. 214.

DRAWING AND DESIGNING. and No. spring

The

4" and 4^ valves.

8 for

may be

outside diameter of the

.5 that of the valve-disk.

Five to six coils

will give a suitable elasticity.

Make drawings

Exercise 103. valve, as

full

shown

Fig. 214, to the dimensions given.

in

Scale

size.

These valves are opened and closed by

Globe -valves. hand. is

for the india-rubber flat-disk

The

valve in Fig. 2 14

is

for steam.

used for cold water the valve-face

india-rubbei, and when

for hot

is

When such made

a valve

of leather or

water the india-rubber

is

mixed with graphite.

The

construction of the valve

is

so plainly

shown

in Fig.

215 that a description seems unnecessary. Exercise 104.

Make drawings

of globe-valve as

Fig. 215, and also a right-end elevation.

This

Stop-valve (Fig. 216). controlled by hand. is

The

is

shown

Scale full

in

size.

another style of lift-valve

particular valve

shown

in the figure

used as a throttle-valve by the Ball Engine Co.,

who kindly

sent drawings.

Let

= thickness of casing / = pressure in Ibs. per t

d

;

square inch; diameter of the sphere in inches;

/= safe Take 2000

bursting strength of material.

for cast iron

use a factor of safety

and about 2200

8,

and 17,500 for yellow brass, and which gives 2500 for the former

for the latter;

then

VALVES, COCKS,

FIG. 215.

AND

OIL-CUPS.

293

2 94

DRAWING AND DESIGNING.

P-'H FIG. 216

AND

VALVES, COCKS,

The for

of the valve

lift

winged

lift-valves.

OIL-CUPS.

2$$

may be determined by formula (i) The valve and its seat must pass

through the valve-chest, so the opening should be made about outside diameter of the valve-seat. J-" larger than the length of the thread on the valve-stem

The

the length of the nut Exercise 105. in Fig.

216.

Make

+

lift

of valve

Make drawings

Scale

4."

=

+

is

equal to

J" for clearance.

of the stop-valve as

shown

i foot.

the diameter of the inlet 6f" to the root of the

shown

thread, instead of 6" as

Boiler Check-valve.

the figure.

in

Fig. 2

1

7

shows working drawings of

the Foster Safety Boiler-check.

Make drawing

Fxercise 106. as

shown

of the Foster Boiler-check

Scale, full size.

in Fig. 217.

Cocks. Cocks are valves which operate with a rotary The most common style of cock is that which conmotion. sists of

a plug

made

in a seat of the

In Fig. 218

O is

in

the form of a truncated cone rotating

same shape

P is the

cast

on a pipe.

plug, and

C the casing or

the opening through the plug.

By

one direction the openings are brought

A

and outlet

cock will

is

B

of the pipe or casing.

conical seat.

rotating the plug in in line

with the inlet

In this position the

open. Further rotation through 90

in either direction

bring the openings in the plug opposite the solid parts of

the casing and close the valve. Exercise 107. in Fig. 218,

and

Make drawings in

of the blow-off cook

addition to the views given

make

shown a half

and half sectional end view. Scale, full size. In Fig. 219 is shown a blow-off cock which is really a wing-valve, opened and closed by a piston which in turn is op-

sectional plan

296

DRAWING AND DESIGNING.

VALVES, COCKS,

AND

OIL-CUPS.

29

;

298

DRAWING AND DESIGNING.

VALVES, COCKS, crated

on

its

by means seat

pressed air

P the

of

compressed

AND air.

by the steam-pressure is

piston

OIL-CUPS.

The wing-valve Fis held

in the boiler.

introduced into the cylinder

is

299

C

When

com-

through the pipe it and allow*

pushed against the valve, opening

ing the contents of the boiler to blow through the cock into the discharge-pipe D. Exercise 108.

219.

Make complete drawings

as

shown

in Fig.

Scale, full size.

Oil-cups.

There are many forms

of oil-cups.

Figs.

220

DRAWING AND DESIGNING. ow

the construction of some of the oil-cups es of the

Lehigh Valley Railway.

ne of the simplest forms of oil-cups. ,

voir

is

filled

cast in

one piece.

with waste and

oil.

When

The

charged, the reser-

This cup

is

used on the

link-hanger. Fig. 221 shows another simple form of oil-cup, used to oil

the rocker-box and cross-head.

VALVES, COCKS,

;

OIL-CUPS.

301

drawing of the oil-cup for the main rod, front cross-wires prevent the waste from being thrown out.

Fig. 222

end

AND

is

a

Fig. 223 shows another form of

The

stem.

flow of the oil

is

oil-

cup used on the valve

regulated by the spindle S, and

167mS.

W BEBRAZED

FIG. 223.

the duty of the spring of

.jig."

brass wire

Fig.

J-"

is

to hold

it

in position.

This

is

made

long when unloaded.

224 gives a form

of oil-cup for the front

end of the

302

DRAWING AND DESIGNING.

r

FIG. 224.

VALVES, COCKS,

AND

OIL-CUPS.

MILLS,

WTHDS.

FIG. 225.

303

DRAWING AND DESIGNING.

304

main rod on cross-head. flow of the

oil is also

Fig. 225 of the oil

is

is

It will

be seen that

in this case

the

mechanically controlled.

a form of cup used on the guides.

in this case also

The

flow

regulated by the raising or the

lowering of the spindle by hand. Exercise 109. structor, of

220

to 225

ing-paper.

Make

one or more of the

when

it is

as

drawings,

desired to

Scale, full size.

oil-

fill

directed

by the

in-

cups illustrated in Figs.

unoccupied space on draw-

CHAPTER

X.

ENGINE DETAILS.

The

The

Plain Slide-valve

construction of

all slide-

valves must be such as to satisfactorily meet the following re-

quirements: 1. To admit steam to one end only of the cylinder at a

time

;

2.

end

To

allow the steam in the cylinder to escape from one

at least as 3.

To

soon as steam

is

admitted at the other end

;

prevent steam from entering the exhaust-port from

the steam-chest.

pal its

During one revolution of the crank there are four principoints reached and passed by the valve in the course of travel 1.

:

^^ point of admission, when

cylinder. 2.

(See Fig. 236, Plate

The

cylinder. 4.

I.)

The point of cut-off, when steam

tering the cylinder. 3.

steam begins to enter the

The

prevented from en-

is

(See Fig. 233, Plate

point of exhaust, (Fig. 235, Plate

when steam

I.)

is

released from the

I.)

point of compression,

when the exhaust

is

closed.

(Fig. 234, Plate I.) 305

DRAWING AND DESIGNING.

3 o6

In Fig. 226 valve, is

given a longitudinal section of a plane slide-

and also of the valve-seat

shown

and

is

exhaust-port.

The

F= is

The

valve

Kare the steam-ports

valve-face

the valve with a length equal to

Outside Lap, or simply lap

of the cylinder.

X and

in its central position,

Z the

S

7J"

is

the under side of

+ 2L.

the darkened portion

L

of

when the valve

is

in

FIG. 226.

the valve which overlaps the steam-port its

central position.

exhaust, but

it

Lap has no

shortens the time the port Inside Lap, laps the

effect

on compression or

hastens the cut-off, prolongs expansion, and is

open.

the smaller darkened portion / which over-

bridge between the steam- and exhaust-ports, pro-

longs expansion, hastens and increases compression, retards

ENGINE DETAILS.

307

the exhaust, but does not affect the admission or point of cut-off.

The Travel of the valve tance if

it

moves from

its

is

equal to twice the total dis-

central position in either direction

or

;

the arms of the rocker are of equal lengths, then the travel of

the valve

is

equal to twice the eccentricity of the eccentric.

" Eccentric and It is also equal to twice the Straps.") (See sum of the width of the steam-port and lap plus the overtravel

if

any.

The Lead Angle

is

the angle

made by

the centre-line of

the crank with the centre-line of motion of the engine the crank

is

at the point of admission.

The Lead

is

the

To

I.)

I.)

amount which the valve has opened the

steam-port at the beginning of the stroke. Plate

when

(See Fig. 236, Plate

(See Fig. 231,

obtain smooth running, increased speed should

have increased lead, and when the lead operation of the valve

is

is

increased every

quickened.

The Angle of Advance of the eccentric is the number of degrees which the centre-line of the eccentric is over 90 ahead of the centre-line of the crank without a rocker, and with a rocker the crank.

the

it is

The

first

number

of degrees short of

90 behind

case

illustrated in the

diagram

Plate II, as follows: Let a line 90

Then

ahead of

COE

is

it,

and

is

AO be OE

AO

the angle over 90

the angle is

ahead of the crank, and

For the case with

be the centre of the crank as before, and

90 behind

it,

and

DOF

is

in

CO

the centre-line of the eccentric.

therefore the angle of advance. let

the centre of the crank,

OF the centre-line

a rocker

OD

of the eccentric.

the angle short of 90

therefore the angle of advance.

is

a line

Then

behind the crank, and

DRAWING AND DESIGNING.

308

Inside Clearance

the

is

opposite of inside lap, instead

of the valve overlapping the bridge

shown

at / in Fig. 226,

it

when on the

centre;

shows a clearance between the

as-

in-

and the bridge. Inside clearance hastens exhaust, delays compression, but has no effect on the side edge of the valve

cut-off or admission.

Overtravel

is

travels after fully

Plate

I.

It

the distance the steam edge of the valve

opening the port, as shown

in

Fig. 232,

increases the sharpness of the cut-off, retards

compression, and gives a later release. Cylinder Clearance

all

is

the piston and the valve

that space between the faces of

when

the piston

is

at the

beginning

of the stroke.

Piston Clearance

the cylinder-head.

the distance between the piston and

is

This clearance

is

to prevent the piston

from striking either cylinder-head when the brasses on the connecting-rod wear and cause lost motion. Point of Cut-off

is

the point on the crank-circle which

the centre of the crank reaches live

when the

valve cuts off the

steam from the cylinder, and for the remainder of the

stroke utilizes the expansive power of the steam.

233, Plate

(See Fig.

I.)

Compression of the steam follows the closing of the exThis is haust before the piston has completed its stroke.

done to obtain a yielding cushion for the reciprocating parts to come to a full stop without shock before beginning the return stroke.

Expansion begins to the point

w

at the point of cut-off

of exhaust.

(See Figs. 233

and continues

to 235 in Plate

ENGINE DETAILS. During

309

this period the valve travels a distance equal to the

outside lap plus the inside lap.

The Allen-Richardson

This

Balance-valve

the most popular combination slide-valves and

is

locomotives, stationary and large marine engines. clearly

shows the

this valve.

is

one of

used on Fig. 227

different parts used in the construction of

The balance

is

effected

by means

of four rect-

FIG 227.

angular packing-strips

5

fitted into

grooves on the top of the to hold the packing-

valve. Semi-elliptic springs Z are used strips against the pressure-plate P when

the chest, but

when steam

is

there

is

no steam

admitted to the chest

it

irk

forces

the strips against the pressure-plate and sides of the grooves,

forming a steam-tight joint and preventing the steam from acting on that part of the top of the valve enclosed by the four packing-strips.

DRAWING AND DESIGNING.

3IO Exercise

Make drawings

no.

Scale 8"

also a half plan of the top.

The shown

as

Allen feature of this valve

at

A

just

is

shown

=

I

in Fig. 227, foot.

the supplementary port

By means

above the exhaust-arch.

additional port steam

is

and

of this

admitted to the same steam-port

in

the cylinder from both sides of the valve at the same time,

thereby increasing the steam-supply with short cut-offs.

advantages of this valve over the plain slide-valve objections to

it

The

and the

are discussed in the proceedings of the fol-

lowing societies:

A.

S.

M.

E.,

vol.

May

20,

1899;

The

Western Railway Club, March, 1897; Am. Railway M. M. " " Locomotive Association, 1896; and in the up to Date by Chas. McShane. *

The American Balance

The American

Slide-valve.

It consists of Balance is applied to any type of slide-valve. a steam-tight joint being formed between the valve and the under side of the steam-chest cover, thus excluding live-steam

pressure from a given area.

(See Fig. 228.)

This joint

is

formed by a bevelled snap-ring which, when in place, is The cone or cones are either slightly expanded over a cone. cast with the valves or bolted to

The mechanical

it,

as circumstances require.

construction of the balance

is:

First, the

cone or two cones, where necessity requires, are either bolted The snap-rings, which are bevelled

to or cast with the valve.

on

their inner side to a corresponding degree with that of the

cone, are bored smaller in diameter than their required work-

ing diameter so that, by their being forced

by

down on

the cone

the placing of the steam-chest cover in position, the rings

* The above description was furnished by Mr. Manager of The American Balance Slide-valve Co.

J.

T. Wilson, GeneraX

ENGINE DETAILS. themselves are under tension and their

own

elasticity

311

are

thus supported by

The steam when

when not under steam.

admitted to the steam-chest exerts a pressv-re on the entire circumference of the ring, which has a tendency to close decrease

its

diameter, and owing to

its

it

or

bevelled face and the

taper of the cone the steam also acts to

lift

it.

careful

By

FIG. 228.

consideration of the operation of this ring,

now being

held by

the steam-pressure tightly against the face of the cone, at

once be seen that

moves

all lateral

wear

is

is

shut

drift, as in

off

It will

absolutely compelled to assume

ing position by the pressure on

its

will

avoided, and the ring

as a part of the cone or valve itself.

noted that the ring

steam

is

it

circumference.

also its

be

work-

When

from the engine and the engine allowed to

locomotives, the valve

is

free to leave its seat until

DRAWING AND DESIGNING.

312

This affords per-

the cone comes in contact with the cover.

and ample relief of the air which the piston is forcing from one end of the cylinder, and also a direct communication

fect

with the other end of the cylinder, being formed.

The

which a vacuum

is

cylinders are therefore perfectly relieved

by allowing the valve

The

in

to

lift

\"

off its seat.

bevelled feature in the ring renders the ring self-sup-

FIG. 229.

when not under steam, and supported by the steampressure when under steam, automatic adjustment for the porting

wear, positive action under the steam-joint.

It

renders

rings of respective size

Owing

all it

conditions, and self-maintaining possible also to duplicate the

in repairs.

to the absence of lateral

wear on the cones new

The

rings can be duplicated at any future time.

of balance can be secured affected

by back or upward

by

this design,

pressure.

greatest area

because

The

it

is

least

valve in order to

ENGINE DETAILS. leave

its

must

seat

first

3'3

expand the taper ring against the

chest-pressure acting on its circumference. The features enumerated all depend Fig. 228 tives. is

upon the taper. a double-cone balance-valve used on locomo-

is

The improved T

clearly

Fig.

shown 229

is

ring, the invention of

J.

T. Wilson,

a single-cone balance-valve for use

on com-

A

double-cone valve of this kind on the Japanese cruiser " Chtose," the rings of which

pound stationary engines. is in use

Mr.

in the figure.

FIG. 230.

are three feet ten inches in diameter, while that in Fig. is

229

only twenty inches diameter.

in

Exercise

Scale

6''

=

i

Make drawings

of

Fig.

230 as shown.

the

many diagrams

foot.

The Bilgram Diagram.

Among

devised to determine quickly and accurately the position of

the valve for any position of the crank, that due to Mr.

Hugo Bilgram

is

one of the simplest and best.

DRAWING AND DESIGNING.

ENGINE DETAILS. In Plate

AB

I let

ameter to the

$15

represent the valve circle, equal in di-

and LI the centre-line

travel of the valve,

From At

the crank rotating in the direction of the arrow. oft"

lay

the angle

EOB,

of

equal to the angle of advance.

B E

describe the arc bgk with a radius equal to the inside lap,

and

afd with a radius equal to the outside lap. Crank positions drawn tangent to these arcs at a, b, k, and d will give the points of cut-off, compression, release, and adalso the arc

mission respectively, as indicated in the figure.

Let us follow the crank through one revolution, beginning with the dead-point A. In this position de is equal to the outside lead, and the valve has

Ee equal to clearly shown in

moved from

its

central posi-

tion a distance

the lap plus the lead.

relations are

Fig. 231.

which the valve has travelled from

X the left-hand steam-port

c gives the distance

central position,

its

shown open

is

These

to steam an

and

at

amount

equal to the lead when the piston

is

forward stroke, and the eccentric

connected directly to the

valve,

i.e.,

When

OE

is

at the

the crank reaches the position L* perpendicular to

the valve will have travelled from

EO.

This

is

ing of the port t

As when

X to steam

its

central position a

the extreme position of

equal to Of, and the overtravel

is

the actual width of the steam-port being

the crank leaves the crank

central position

is

is

the

=

Om.

the valve begins to return, and

at L* the distance of the valve

equal to the lap ab.

to steam, and cut-off

When

D

crank

is

is

accomplished at

its

The maximum open-

xorward travel, as shown in Fig. 232.

mf

its

without a rocker.

distance equal to

to

beginning of

L

1

the

as

Port

X

shown

is

from

now

its

closed

in Fig. 233.

right-hand steam-port

is

DRAWING AND DESIGNING. closed to exhaust, and compression begins as

shown

at

F,

Fig. 234.

When

U

on the point of opening port X, Fig. 235, to release the steam which was under compression during the time the crank moved from

U to L

l

the crank reaches

At crank

the valve

L we

find, as

is

shown

in

Fig 236, on the point of admitting steam to port F, and at B the backward stroke of the piston begins, the valve having opened the port an amount equal to the lead de, equal .

position

that the valve

is

to the opening

shown

At crank shown

its

in Fig.

X

r

position

valve has attained to that

at

in Fig.

maximum At

232.

steam from port F, and

231.

and valve position Fig. 237 the

A

at

travel in the opposite direction 3

/

the

,

Fig. 238, the valve cuts off

new forward

stroke begins.

r

FIG. 239.

Exercise 112

(Fig. 239.) Given.

Travel

= = Cut-off = Compression Width of steam-port =

Angle

Required

Outside

5". of advance.

.

.

30.

8o# of stroke. Outside

90$ i

lap.

Inside lap. lead.

of stroke. Inside lead.

J''.

Maximum Overt ravel.

port opening.

ENGINE DETAILS.

AB

Draw

CO

and

scribe the valve-circle arc

ACB

with a radius equal to half

=

the travel or eccentricity of the eccentric of twice

From

size.

full

the angle of advance

A

and from

Let

AB

E

this

;

is

the crank

Ea

equal to

represent the stroke,

Draw OL* through

/'.

position at the point of cut-off.

With

OL* draw Ea.

perpendicular to

EOB

80$ of a stroke of 24", and erect a

perpendicular to cut the valve circle in

r

2\" to the scale

the angle

lay off

30.

Al

lay off

B

De-

one another.

right angles to

at

From A

describe the lap circle afd.

Through

centre

E and

radius

lay off

A2

=

90$ of

the stroke, and erect a perpendicular to cut the valve circle at b.

Through

draw OL*, which

b

With

point of compression.

E

describe the inside lap circle.

point

the crank position at the

as centre

Draw

OU

and Eb as radius tangent to bgk at

k.

At O with Then Ea

h.

is

=

a radius

the port opening describe the arc

Eb the maximum

the required lap,

is

lead, ke the inside lead, (9/the

inside lap, de the

port-opening, and

///the overtravel. Exercise 113.

(Fig. 240.)

Given.

= = =

Cut-off

Lap Lead

Draw

I

\"

.

Travel of the valve.

Angle

2 parallel to

of advance.

i"

'.

to a scale equal to twice full size

Draw OL\

angles. line

Required.

8o# of stroke.

AB and CO at right

the position of crank at cut-off.

AB

at a distance

above

it

Draw

equal to the

4 parallel to AB at a distance equal to With a radius equal to the the lap plus the lead above it. lead ed.

Draw

line 3

DRAWING AND DESIGNING. given lap find by lap

circle

and

d.

trial

a centre on the line 3 4, and draw the

afd tangent

Then through

E

to OL*, and line

with centre

O

2 at the points a

i

describe the valve circle

ACB.

AB is

the travel of the valve, and

EOB

the angle of aa-

vance.

FIG. 241.

Exercise 114

(Fig. 241.) Given.

= 8o# of the stroke. = 90$ of the stroke. Admission Maximum port-opening = Of (Fig. 240).

Cut-off

Required.

Travel of the valve

Lead.

Angle Lap.

of

Advance.

ENGINE DETAILS.

AB

Draw

and

CO

Draw OL, the posiDraw OL*, the admission.

at right angles.

tion of the crank at the point of

crank position given

maximum

the line

Through

/

circle

draw fa

AB

is

LOD

with

OU, and make fn = fin. nm, and aE parallel to mf.

perpendicular to to

parallel

ACB, and draw

Then

Bisect the angle

centre of the lap-circle will be on this

the centre of lap

is

and arc /with a radius equal to the

port-opening.

The

OE.

Draw fm

line.

E

at cut-off,

circle.

Through

the line

Ee

E

describe the valve

at right angles to

the travel of the valve,

Ea

AB.

the lap,

BOE

the angle of advance, and de the lead.

Exercise 115.

(Fig. 242.) Given.

= =

Cut-off

Lead

Maximum Draw

Draw

OL*

AB

parallel to

.

3 4,

and

E

line

the lead-line

it.

a radius equal to the the centre

Lap.

i".

port-opening = Of (Fig. 240). AB and CO at right angles.

position

and

Required.

80$ of the stroke. Angle of advance.

With

maximum

2.

Through

this

Locate the crank

2 at a distance de

O

from

describe arc 3 4 with

port-opening.

Find by

drawn tangent to centre draw OE.

of a circle that can be I

I

centre

Travel of valve.

OL

trial 9 ,

arc

DRAWING AND DESIGNING.

320

Then

OE

BOE

is

the angle of advance,

Ea

is

The Zeuner Valve Diagram

In Plate II

sent the stroke of the piston, the circle

the crank-pin, and

From C

OE

the lap, and twice

equal to the travel of the valve.

lay off

L

let

ACBD

AB

repre-

the path of

the centre-line of the crank.

OE

equal to the angle of advance, and on

as a diameter describe the valve circle equal to half the

when no

travel of the valve or eccentricity of the eccentric

rocker

is

From

used.

equal to the outside

At

centre

O

draw the

arcs abc

and gfk

and inside laps respectively.

the beginning of the forward stroke the true position

of the crank

would coincide with AO, and the centre-line of

the eccentric with OE.

Now

since the position of the point

eccentricity

and

if

is

circle

fixed for a given

E

will

always be

having

OE

as a diam-

and angle of advance, the point

found on the circumference of the eter;

E

the valve circle together with the crank be rotated

around the centre

O

in a direction

intersection with the line

OB

opposite to the arrow,

from

which the valve has travelled from the crank has

O

its

moved through any given

But instead

of rotating the crank

remain fixed and rotate the

line

OB

will

its

be the distance

central position after

angle.

and valve

circle let

them

as an imaginary crank in

the direction of the arrow, and the same results will be obtained in a

much

Draw OL,

simpler way.

the imaginary crank, through the point where

the lap arc abc intersects the valve circle at the point

c.

The

position of the valve will then be at the point of admission,

because the valve

will

have travelled from

a distance equal to Oc, equal to the lap.

its

central position

ENGINE DETAILS.

321

DRAWING AND DESIGNING.

322

This

is

/ of

port

X

When

The

in Fig. 243.

valve

the valve

is

is

on the point of admitting steam to the

just 'before the

beginning of the forward stroke.

the imaginary crank reaches the position

OB

have travelled a distance equal to Oc from

will

OB

position and,

travelling

and the steam

opposite to the imaginary crank,

in a direction

edge

shown

clearly

the valve

its

central

being a dead-centre, the valve will have

opened the port X to steam an amount equal to the lead, and

Y to

the port

When

exhaust an amount equal to pq, Fig. 244. the crank has reached the position OE the valve

will

then have attained the extreme position of

The

shaded part bk shows the

its

travel.

opening of the steam-port, and ke the amount of overtravel, and at the same time the

port

Y is

tion fjj

fully

open to exhaust, as shown by the shaded por-

JF is

and

full

the exhaust overtravel (Fig. 245).

The valve now returns and when the crank arrives at

until

cut-off takes place, as

When the valve

At

Og

the crank is in its

its

to exhau. ;t,

as

unt.il

begins to close port

L

n

shown

in

is

and the port

L

1

fully closed

OE

in Fig. 247.

the valve has travelled a distance

X

The

the port

is

is

about to open

port continues to

fully

tinues so until the crank reaches the position to close, and

y

in Fig. 246.

Fig. 248.

at the position

X

fully closed and

is

middle position, as shown

central position,

r

R

the position L* at right angles to

in

the crank position

from

open,

is

shown

at

L* the port

open and con-

9

L when

it

begins

when the crank reaches L\

Now

,

compression begins and continues through the angle L*OL.

At L

the valve has returned to the point of admission a

before the beginning of the

At crank

position L*

it

new forward

will

little

stroke.

be seen from Fig. 250 that the

ENGINE DETAILS.

323

X

the port fully open to exhaust, port Fis fully open to steam, extreme the and that the valve has reached position of its travel for the

tion

shown

just the opposite of the posi-

backward stroke

in Fig. 245.

C

FIG. 252.

Exercise 116. as in Ex.

1

Make

right angles.

crank-pin.

=

AB

From C 30,

the same conditions

Draw

Bilgram diagram.

stroke of the piston, and

advance

Assume

252).

(Fig.

12 for the

to let

any convenient

ACB

AB

and

CO

at

scale equal to the

represent the path of the

lay off angle

OE

equal to the angle of

with a scale equal to twice

full size.

On Ok

as a diameter, equal to half the travel of the valve, or 2 j-", de-

From

scribe the valve circle Oakc. of the stroke, arc in

Z

3 .

B

lay off

Bl equal

to 80$

and erect a perpendicular to cut the crank-pin

Draw OL*,

Through the point

a,

the position of the crank at cut-off.

where

OL

as centre describe the arc abc.

3

cuts the valve circle, with

From

B

lay off

B2 equal to 90$ Draw OL and

and erect a perpendicular to L*. the through point g, where OL intersects the valve of the stroke,

O

9

,

6

with

O

as centre describe the arc gfh.

From

i>

lay off bk

equal to the width of the steam-port, and with centre radius

Ok

describe the arc 3^4.

circle,

O

and

DRAWING AND DESIGNING.

324

Then Oa

the required lap,

is

lead, $t the inside or exhaust lead,

opening, and

KE the

the inside lap, de the

Og

OE

the

maximum

port-

overtravel.

C

O FIG. 253.

Exercise 117. as given in

Draw

(Fig. 253.)

Assume

AB

CO

and

intersect will

the crank

describe arc abc with a radius

equal to the lap, scale as before. Bisect

Draw OL\

at right angles.

From O

position at cut-off.

lead.

the same conditions

Ex. 113.

Lay

off

de equal to the

Oa and

Oc, and the point / where the bisectors be the centre of the valve circle which may now

be drawn through the points aOe.

Then is

OE

equal to half the travel of the valve, and

is

COE

the angle of advance. Exercise 118.

(Fig. 254.)

Given.

Point of cut-off.

.

.

Point of admission

Lead

Draw

AB

and

OL

and

OL\

tions

Required,

=

80$ of stroke.

Travel of valve.

= =

90$ of stroke.

Lap.

CO

".

at right angles,

Bisect the angle

Angle

Draw

LOL*

of advance.

the crank posi-

with the line OE.

On OE assume any point as g, and draw gf perpendicular to OB, and gh perpendicular to OL. With center O and radius Oh

describe the arc he.

ENGINE DETAILS.

Now

the angles

gOB

and

gOL

$2$

are constant for a given

admission and cut-off; therefore the lead will vary directly aa the eccentricity.

FIG. 254.

Let

Og be

an assumed eccentricity, then ef will bo

responding lead,

and the given lead

ef as the required eccentricity

is

is

to the

to the

its cor-

assumed lead

assumed eccentricity

Of.

Lay off Ol equal to the given lead, and O2 equal Draw 2g, and IE parallel to 2g. With a radius equal to Oe minus the given lead and

O

describe the arc abc.

On OE

to ef.

centre

as a diameter describe the

valve circle Oaec.

Then

COE

is

the required angle of advance,

centricity or half the travel of the valve, and

Exercise 119.

(Fig. 255.)

Assume

Oa

OE

the ec-

the lap.

the conditions as in

Ex. 115.

Draw

AB and CE at

right angles to each other.

Draw OL\

the crank position at cut-off, Oa, the given lead, and Ob, the

given bg.

maximum

port-opening.

Through a draw ad&t

At

b erect the perpendicular

right angles to

dee with the line Oc, and produce

it

OL\

Bisect the angle

to intersect

fg

at g.

Join

DRA WING AND- DESIGNING. draw cf 'describe

parallel to Ob.

arc/,

to

O A.

cutting ag in

O^

parallel to kc, cutting

With

in the

k.

point

and cf as and draw a O

c as centre

Join ck,

O

t

.

Draw

O^e parallel

\

t

Then Ock

is

the required angle of advance, O\a half the

required travel of the valve, and O^e the lap.

FIG. 255.

Engine Frame or Bed-plate. Frames This is engines are usually made of cast iron.

for horizontal

the most suit-

able material owing to the complicated sections found in

frames, and also because Figs. 256 to 258

type.

It is that

it

most

gives the necessary rigidity.

show an engine frame

of the "

"

Tangye

used by the Buckeye Engine Co. of Salem,

Mass. Exercise 120.

258.

Scale li"--

Make drawings I

foot.

as

shown

in

Figs.

256 to

ENGINE DETAILS.

327

23A WING

A*TD J

Steam-engine cylinders are almost always made of a tough, close-grained cast iron as hard as can be safely Cylinder.

worked.

Diameter of Cylinder, D.

Let

P=

the

mean

effective pressure of

square inch

L A=

=

M. E.

P.

length of stroke in feet

steam

;

area of piston in square inches

-

I.H.P. is

therefore

the absolute

boiler

=

ratio of

steam

Then

+

expansion

is

cut

D= u

5 Iks.

J

=

7%

r

l

ss

i.e.,

the

between

length of stroke in inches

by piston

--

in

inches

~

before

back-pressure.

t.

of

pounds; diameter of cylinder "

i

steam, f

off.

boiler-pressure

Whitham

be found from the

log. r

Thickness of Cylinder, l

A

=

and cylinder.

^ P= +- hyp.

Let P =

may

horse-power, and

pressure of

initial

distance travelled

i

D

;

:

gauge-pressure

r

so

P

effective pressure

following formula

=

33QOO ;

The mean

Let/

X

=

pounds per

;

N= number of strokes per minute. PL A N = I.H.P. or indicated Then A

in

steam per square inch

in

in inches.

recommends the following formula

for hor-

izontal or vertical cylinders of large or small diameter

where

ENGINE DETAILS. provision

is

made

idity are secured

for reboring

and

sufficient strength

and

rig-

:

/

=

0.03 V1\D.

The length of cylinder between Length of Cylinder. heads = Stroke -[- thickness of piston -|- the sum of the piston clearance at both ends.

The

Cylinder Head.

cylinder head or cover next to the

sometimes cast on the cylinder. The thickness of the cylinder head recommended by Prof. Seaton is crank

is

2OOO

The

thickness at the flange where the head

cylinder should be

Cylinder -head

-J-

greater than

studs in locomotives

is

bolted to the

this.

The diameter

Bolts.

is

of

cylinder-head

usually f ", and their pitch abour

4

times their diameter.

For stationary and marine

practice

"

"

Ripper

gives

4

= d= D

diameter of studs;

p

maximum

/=

4000

where n

number

diameter of cylinder; pressure of steam;

to 5000.

Steam-ports. fro. /i

of studs;

The steam-ports which conduct

the valve-chest to the cylinder should be as short and

direct as possible, but large

and

the steam

of easy curvature.

enough to prevent wire-drawing

DRAWING AND DESIGNING.

33

The

length of ports in locomotives

is

usually

i"

less

than the diameter of the cylinder. In other types the length

The

generally

area of the steam-port

as follows

A= v

made

given by

is

o. 8/7.

many

authorities

:

a

where

is

=.

AV ,

v

area of the piston in square inches

= velocity of steam

through the port

;

= 6000 feet per

minute;

V = velocity

of piston in feet per

minute (from 1000

to 1200);

a

= area of steam-port.

Figs. 259 to 262

show the working drawings

of a horizon-

made by the Buckeye Engine Co. shows a longitudinal section through the centre of Fig. 259 the cylinder, Fig. 260 a cross-section through the exhaustpassage, Fig. 261 a back-end view showing the opening for tal

a

steam-engine cylinder

valve-rod, and Fig. 262 a plan. Figs. 263 and

this cylinder.

264 are the heads and covers suitable

When

in position

of the cylinder, shown in Fig. 261, the frame shown in Fig. 261. Exercise 121.

Make drawings

in Figs. 259 to 262. Exercise 122.

that shown

(Scale i\"

Make

in Figs.

for

on the engine-frame the end is

bolted to the end of

of steam-cylinder as

=

shown

i foot.}

the design of a cylinder similar to

259 to 262 to develop 100 I.H.P. Stroke

30"; steam-pressure 90 Ibs. per square inch; cut-off of the stroke. Number of strokes per minute 22o.

at

ENGINE DETAILS.

331

DRAWING AND DESIGNING.

33 2

Make drawings

Exercise 123. in Figs.

263 and 264.

Pistons.

which

by

A

slides to

(Scale /J"

piston

and

of the cylinder

heads shown

= i foot.)

that part of an engine or

is

fro inside a

fluid pressure or acting

pump

hollow cylinder either driven

against fluid pressure they are

usually of circular section and are

made

of brass,

wrought

iron,

cast iron, or steel.

A

piston with valves which permit the fluid to pass from

one side to the other

is

and

called a bucket

is

used in

pump

cylinders.

A single-acting of the cylinder,

is

piston, guided called a plunger

Steam-pistons.

A

by the stuffing-box instead and

is

also used in

pumps.

steam-piston should be designed so

as to prevent the steam from passing from one side of the

piston to the other.

The inder

A

spring packing-rings should not press against the cyl-

more than

is

necessary for steam-tightness.

piston should

be no

heavier than

is

necessary

for

strength.

The weight

of the piston should be distributed so as to

prevent the excessive internal wear of the cylinder.

The

piston must be firmly connected to the piston-rod.

Many

different designs

have been adopted to secure the

above requirements. is a plain box piston, used by the Southwark Machine Foundry Company. It is cast in one piece; the core being removed by three holes, shown in the front, which are afterwards plugged up. The two small holes are for eye-

Fig. 265

&

bolts which are used to

when

necessary.

remove the piston from the cylinder

The packing consists of two

cast-iron spring

ENGINE DETAILS. rings cut as

into place

shown

The rod

in detail in the figure.

forced

is

by pressure and the ends riveted over.

Make drawings

Exercise 124.

shown

as

in

Fig. 265*

= I foot.)

(Scale 6"

Fig. 266.

This

is

another style of box pattern, used by

the Ball Engine Company.

method

333

The

style of packing

and the

shown

of securing the piston-rod are plainly

in the

figure.

FIG. 266.

Make drawings

Exercise 125. in addition

piston.

make

=

Fig. 267 shows a

and two

common

Fig.

267

Make drawings engine whose

Take dimensions from Table Fig. 268, a cast-iron

a

T

The rod

and held by nut over which the end an

and

built-up piston used largely in

cast-iron spring-rings.

for

in Fig. 266,

I foot.)

It consists of a spider, S,

Exercise 126.

shown

a half end section through the centre of the

(Scale 6"

locomotives.

as

36.

is

forced into place

of the rod

is

of a built-up

cylinder (Scale 6"

box piston used

Empire State Express locomotive. shown in the figure.

ring, a follower, F,

in

is

=

riveted.

piston 18''

X

like 24''.

I foot.)

the cylinder of the

Its construction is plainly

DRAWING AND DESIGNING.

334

Make drawings

Exercise 127

268.

(Scale 6"

Fig. 269

is

=

of the piston

shown

in Fig.

/ foot}

box pattern

a cast- steel

T

cast in

two parts and

' 3

7/ FIG. 267.

TABLE

15

16

36.

$

18

19

20 22

18

4i

81

t

ENGINE DETAILS.

FIG. 268.

335

336

DRA WING AND DESIGNING. \

ENGINE DETAILS.

337

This piston is made by the Baldwin " Vauclain " Locomotive Works for the compound locomo-

held together by rivets.

tive.

Make drawings

Exercise 128. (Scale 4" =

as

shown

in

Fig.

269.

i foot.)

270 shows the cast-iron pistons used stationary engines built by Mclntosh & Seymour.

in

Fig.

The packing

composed of cast-iron method shown in

is

kept in place by the

The arrangement

for securing the rod

tandem

spring-rings cut and detail in the figure.

is

shown

in detail in

Fig. 68, page 103.

Exercise 129. (Scale 3"

=

Make drawings

as

shown

in

Fig.

270,

i foot.) is

Fig. 271

a built r_up piston for the

engines made by

the Buckeye Engine Co.

Tangye It

stationary

consists of a

and adjusting-screws. There are no springs; the screws act on an uncut junk-ring, so can only be used for

spider, follower,

The

not for packing.

centring,

packing-rings are turned

so as to pack larger than the bore of the cylinder elasticity.

They may

or

thin where cut, and full If

made

eccentric,

(Scaled"

=

their

own

not be turned eccentric, that

may

is,

thickness opposite the cut.

it

is

for the reason that they will

more nearly round when sprung

be

into the cylinder.

Make drawings

Exercise 130.

by

as

shown

in

Fig.

271.

I foot.)

suitable for cylinders under Fig. 272 shows a water-piston

9" diameter.

The

piston-rod

is

fitted

to the head with a shoulder to

drive the piston, and the rod

The

follower

is

also held

by

is

secured in place by a nut.

a nut and lock-nut.

By

this

338

DRAWING AND DESIGNING.

ENGINE DETAILS.

339

means the follower and packing may be adjusted or renewed

The packing

at will.

is

made

of layers of cotton cloth

and

sheet rubber.

Make drawings

Exercise 131 in Fig.

of water-piston as

shown

(Scale full size.}

272.

In steam and other engines the con-

Connecting-rods.

necting-rod connects the rotating crank with the reciprocating cross-head.

There are many

and various

styles of connecting-rods,

methods are employed for taking up the wear of the brasses. Figs. 273 to 276 show good examples of rods used in stationary, locomotive, and marine engines of the most modern types. Fig. 273 their

"

is

the rod used by the Buckeye Engine Co. for "

Tangye

type of engine.

The

crank end

is solid,

brasses are lined with babbitt, and adjustment for wear

is

the

had

by means of a tapered steel block and screws. The crosshead end is called a strap end. The strap is firmly bound to the end of the rod with a cotter-key and gib, which also controls the

adjustment for wear.

.

274 has strap ends front and back. Keys are inbetween serted the straps and the rod to prevent the shear of Fig.

the strap-bolts.

The

construction of this rod and the

employed to take up the wear

The

Erie City Iron

Works

are plainly

shown

in

method

the figure.

use this rod on their stationary

engines.

Exercise 132.

(Scaled"

=

Make

the drawings as shown in Fig. 273.

Make

the drawings as shown in Fig. 274,

i foot.}

Exercise 133*

340

DRAWING AND DESIGNING.

ENGINE DETAILS.

34'

DRAWING AUD DESIGNING.

34 2

except that half of the plan i foot.} (Scale 6"

shall

be a section through

XX.

=

Fig. 275

Railroad

is

the connecting-rod used by the Pennsylvania

Company on

crank end of this rod

A.

is

an improved design invented by Mr.

Vogt, mechanical engineer of the company.

S.

improvements before, the back end of the rod

method ent,

.

He

ex-

as follows:

plains the

As

The

their fast passenger-locomotives.

of closing the

and the key

open end

for closing the

is

of the fork

forked, but the is

entirely differ-

main brasses has been moved

from the forward side of the brass to the rear, which has another good effect,

viz., as

the brasses in both front end and

back end of the rod wear and are closed up to meet that wear, the actual length of the rod changes but very little, for the reason that the keying of both ends

is

in the

same

direc-

form of the rod the keying was in tion, opposite directions, and as a matter of course the distance from centre of crank-pin to centre of crosshead pin increased whereas

The open end

gradually. first,

by

a

in the old

of the fork in this rod

U-shaped block, the detail of which

is

is

closed >

marked

A

on Fig. 275; next, by the key which is marked B\ and last of all by a combined key and bolt marked C', this bolt clamp-

A

and

forming an enclosed surface for the key to drive against.

To

ing the two

members

of the fork against the block

prevent the slacking up of the nut C, a keeper-block vided at the bottom of the lower

made with

a recess into

member

which the nut

of the fork.

fits

is

pro-

This

and a set-screw for

locking the nut.

The same keeper-block extends forward

the key B, which

is

It is quite

also blocked

evident that there

is

by a set-screw

much

less

is

to

in the block.

chance of shearing

ENGINE DETAILS.

343

DRAWING AND DESIGNING.

344

or offsetting of the bolt and the key in this than there was of

the bolt in the former design

which

but even

;

if it

should take place,

not very likely, the whole thing can readily be dis-

is

connected by,

B

driving the key

first,

out, unscrewing the

nut on the bolt and moving the whole bolt slightly forward,

when

it

can be lifted out at the top.

Make drawings

Exercise 134.

= i foot.} (Scale 6" This form of rod cause

it is

is

shown

as

called a marine

Fig.

275.

connecting-rod be-

often used on marine engines, but

used on stationary engines and

in

it

is

also largely

is

occasionally seen on loco-

is

usually forged solidly on

motives.

The

crank-pin

the rod, and

The

all

end or stub

but the sides

hole to receive the brasses arid

is

finished

by turning

the lathe.

in

sides are then planed and the bolt-holes drilled.

bottom

unless the top

of the brasses are to be thicker than the sides, in

which event the hole or top end

may now be bored

The

will

not be completed until after the cap

of the stub has

been slotted

off

and bolted on

again. It will

be seen that the bolts are turned down to a diam-

eter equal to the diameter at the

does not weaken the bolt, but

The

cross-head end of this rod

cross-head, but is

is

it

will

in

given

Exercise (Scale 2"

=

135.

of the threads.

more

made

This

elastic.

forked to suit the

the large end.

detail drav/ing of the bolt in Fig. 65,

is

it

be seen that each half of the forked end

constructed the same as

A

bottom

makes

and

its

locking arrangement

page 96.

Make drawings

i foot.}

as

shown

in

Fig.

276.

ENGINE DETAILS. Thrust of Connecting-rod. ing-rod let

is

Assuming

345 that a connect-

equal to a pillar rounded or jointed at both ends,

D=

diameter of piston

L=

length of stroke in inches

in inches; ;

2.= length of connecting-rod in inches;

P = maximum steam-pressure T = thrust of connecting-rod. When ing-rod

is

the crank-pin in line

is

per square inch;

on a dead-centre and the connect-

with the piston-rod, then

T=-D*P =

W,

4 the total load on the piston.

But

as the crank rotates the

connecting-rod becomes inclined to the centre line of motion,

T increases

and

until a is

as the angle of the connecting-rod increases

maximum

not cut

The

is

reached at half-stroke, provided the steam

off before.

value of

crank as follows

T may

be found for any position of the

:

Let AB, Fig. 277, be the connecting-rod, and crank.

The

forces acting

at A

are

on the

BC

the

W, the maximum pressure

piston, and R, the reaction of the guide on the crosshead, and T, the thrust along the connecting-rod.

From

the triangle of forces

T and

7-=

W= AC W

, VAE'-AC''

AB

DRA WING AND DESIGNING.

346

Diameter of Connecting-rod, Circular Section.

Thurs-

ton gives

d

where a

= a V Dl, VP + C

diameter at middle,

for fast engines, jo. 15 \

(o.<08 for

"

moderate speed

" for moderate speed /,

;

for fast engines, ;

length of connecting-rod in feet,

Seatons, Marks, and

Whitham

give

d= 0.0275 8

FIG. 277.

For the diameter 1. 08

at the

times the diameter at the cross

larger at the middle

Whitham gives head end. The rod is

crank-pin end

and tapers about

"

to the foot.

Sennett gives diameter at middle

" necks

= ^60

ENGINE DETAILS. Locomotive Connecting-rods.

The

347 sizes of rectangular

rods of uniformly tapered section are in practice as follows:

Depth of Main Rod. ameter or less the depth

'"

less

On

engines with cylinders 14" di-

of the rod at the crank

less.

Depth of main rod at cross-head end Cyl.

diam.

end

is

made

than the depth of the stub; over 14" diameter,

=

d^.

-J"

DRAWING AND DESIGNING. centrifugal force, will be distributed over the entire rubbing

The

obtained from

running the bearing in a bath of oil, as shown in Fig. 278, where the oilbasin surrounds the journal-box, which can be kept submerged surface.

in

oil,

best

results

are

thus insuring constant and efficient lubrication.

Fig. 278 the oil passes from the oil-basin

box through the hole

OB

to the journal-

and on to the under side

h,

In

of the shaft

ED. To insure a continuous grooves are made on the under

through the hole in the disk

flow

of oil through the holes,

side

and upon the upper side of the projection upon which the disk BD is carried. To prevent lateral motion the end of the shaft is turned to fit the journal-box J which of the journal-box,

t

is

provided with

a

brass

bush

The bush

(B).

is

secured

against turning with the shaft by the projections E, which

between lugs

The under rests

upon

cast

fit

on the inner surface of the journal-box.

side of the journal-box

a surface which

is

J is

slightly spherical

and This

also slightly spherical.

allows the journal-box to be tipped over for a limited dis-

5

tance by means of the set-screws

The down

with that of the shaft. carried

upon

BD, which

a steel disk

until

its

axis coincides

pressure, of the shaft also rests

upon

is

a slightly

spherical projection cast on the upper side of the journal-box

bottom, allowing the whole of the shaft end to remain tact with the disk although the

worn

bush

B

in

con-

has become sufficiently

to allow the shaft to have side motion, thus

making the

bearing adjustable, and capable of maintaining a perfect bearing over

its

ditions.

The

entire surface

disk

BD

is

under

all

ordinary working con-

longer than the shaft diameter, and

prevented from turning with the shaft by the flat sides comThe journal-box is hexagonal ing in contact with the lugs /. is

ENGINE DETAILS.

349

DRAWING AND DESIGNING.

35 in cross-section,

and

is

tapered towards the top to allow

it

to

tip the required distance without increasing the diameter of

^he oil-basin. set-screws

.S

It is

held against turning with the shaft by the

pressing against the

pivot or step bearing in

is

flat

faces.

This form of

suitable for journals from \\" to 3^"

diameter.

As

the velocity ot the bearing surface varies from zero at

the centre to a

maximum

friction increases

with the velocity, the wear will increase from

at the circumference,

Thus

the centre to the circumference.

the smaller the diameter

D of the journal,

it

will

and as the

be seen that

within limits deter-

mined by the pressure per square inch on the rubbing faces, the more will the tendency to wear be reduced.

D will

sur-

be found by the formula

_T

y

4~ from which

7854^ where

P=

intensity of pressure per square inch of projected area,

which with

continuously

7"=

form of bearing running be taken at 300 Ibs.

this

may

;

on the rubbing surface, which is the weight of the shaft and its attachments. Exercise 136Design a bearing of the form shown in Fig. total load

278, to carry a load of 1450 Ibs.

a HALF SECTIONAL ELEVATION, a

HALF ELEVATION, SECTIONAL END VIEW, the

Show

a

planes of section passing through the centre of the bearing, a HALF PLAN and a HALF SECTIONAL PLAN, the plane of sec-

ENGINE DE7 AILS*. rion passing

through the bearing at the

proportions

=D+

The

''.

and the bearing disk

at the centre

The parts dimensioned j

t

unit of

of the brass bush,

be made

may

The

line ab.

thickness

1

35

=

.o8Z>

-f-

y

T

'.

in inches are constant for all sizes of

Scale full size.

o u rnals.

Crank-shaft or Main Bearings.

The bearings

carrying

the crank-shaft of a vertical engine have the greatest pressure acting nearly vertically will

consequently the greatest wear

;

be above and below the shaft, and adjustment

is

effected

by

a two-part bearing, parted on the horizontal centre line,

as

in

170.

Fig.

The

crank-shaft

of

bearings

engines should be designed for horizontal

horizontal

adjustment to take

up the side wear caused by the pull and thrust transmitted along the

and

connecting-rod,

take

vertically to

up that

caused by downward pressure due to the weight of the etc.

wheels,

obtained, with a two-part bearing, at

by parting the bushing

nected

is

generally 'mad 2 at

with the

crank

45. The frame-work

bearings

on

horizontal

generally part of the engine frame, as in Figs.

Three-part Bearing is

shown

in Fig.

An example

up the adjusting-gibs

G

taken up by screwing

in

engines

is

2jg and 280. form of bearing is

taken up in

the screws A, which

move

The

down

In this design, as

and can only be returned to the babbitt strips.

con-

against the shaft.

the cap C.

the bearings wear, the shaft will be

is

of this

279, where the horizontal wear

one direction only, by screwing

is

The

an inclination with the direction of both pressures.

inclination

fly-

Vertical and horizontal adjustment can be

The cap

its is

wear

moved forward and down,

original position

made

also provided with projections

vertical

to

fit

which

fit

by renewing and

into the frame,

over the outside of

DRAWING AND DESIGNING.

352

the frame, thus insuring that nal.

To keep

it

will sit squarely

upon

its

j

)ur-

the cap (C) from being screwed too far aad

FIG. 279.

clamping the each corner.

The

lubricator

which the

These

shaft,

oil is

O

it is

provided with an adjusting-screw

consists of a pocket cast in the cap

conveyed

at

from

to the bearing through the holes //

are filled with cotton to

keep the

oil

from flowing into

the bearing too rapidly. This system of lubrication

is efficient,

ENGINE DETAILS. but very wasteful unless the surplus ing can be caught and used again.

by

casting a hollow projection

bearing, from which the

oil is

353

flowing from the bear-

oil

This

OC

is

done (Fig. 279)

on the frame under the

drained

by the pipe

off

OP to

the bottom of the engine frame.

This form of bearing (Fig. 280) is parted on each quarter of the journal, which allows the wear, caused by the thrust and pull on the connecting-rod, to be

Four-part Bearing.

side. This is effected by screwing down which the the bolts A, pull up tapered wedges W, moving the toward forward the To hold the bolts A C journal. gibs

taken up on either

against turning back, they are provided with a locking arrange-

ment, shown, drawn to an enlarged vertical

bolts

adjustment

The under

CB.

block LB, which ing

it

is

is

scale, in Fig. 281.

obtained by screwing side of the journal

allowed to

move

to adjust itself to the journal, but

the frame.

The top

bearing

down

the cap-

carried

upon a

transversely, thus allow-

longitudinally by projections which

Fon

is

The

fit

TB

is

held against

moving

over the raised part is

held. in position

by

the screws 5, which also serve to hold the gibs (G) in position

and keep the cap from being screwed down too tightly on the shaft.

The

or by filling

it

O may

be used for semi-liquid grease with cotton saturated with oil.

lubricator

Length of Crank Bearing. To calculate the length of a bearing it is. necessary that we should know the amount and The presdirection of the pressure to which it is subjected. sure on the crank-shaft bearings of a horizontal engine

uncertain in

amount and thrust and

amount and

direction.

We

can determine tne

direction of the resultant pressure caused pull of the connecting-rod

is

by the and that due to the

DRAWING AND DESIGNING.

354

weight of the: fly-wheels and shaft, but this pressure either

or

augmented

by the

relieved

may be

transmission of the

power.

A reliable this country,

rule, is

and one which

make

to

is

generally observed in

the length of the bearing equal to

TWICE THE DIAMETER OF THE SHAFT. The Cap. To relieve the cap as much is

from

up well around the bearing, The upward pres practically a ;at plate.

the stresses the frame

and the cap (C)

as possible

is

carried

sure of the cap caused by the angularity of the connecting-rod is

found by the formula

P r

This pressure

may

'~

be augmented by the gearing which

is

used to transmit the power, and, to insure that the cap and cap-studs will have sufficient strength under the worst conditions,

the value of

maximum

where

P= R

The

/

should be increased 100$.

pressure p' on the cap

total steam-pressure

on the piston

ratio of length of connecting-rod to

length of connecting-rod

6 times the throw of crank.

beam on which the

load

is

is

generally

The cap

is in

distributed over

Then the bending moment

is

o

,

is

r~f-

the

;

throw of crank.

made

equal to

the condition of a its

entire surface.

and the moment of

LT* s'stance to bending

Then

be found by the formala

will

Therefore

re-

ENGINE DETAILS.

355

from which

T -*' where

L=

length of cap

T=

thickness of cap;

=

p'

/=

f=

r

x

8

;

on cap;

total load

distance between cap-studs; strength of the material, which may be taken

5000

under side of the cap

The maximum

is

resisted

ft

bottom

at

of thread

= number of studs = strength of material =

pressure (/') on the

by the studs CB.

fore their effective area will be found

Area

at

Ibs.

Diameter of Studs.

where n

X/'

There-

by the formula P'

=

;

of area at

bottom

5000

Ibs.

per square inch

of threads.

Having found the area at the bottom of the threads, turn to Table No. 8, page 66, from which take the nearest diameter of

screw having the required area.

The diameter

of

the

adjusting-studs (A) and the set-screws (s) may be made -J" in diameter when the journal is 6" or less, and increased

J"

for

the

every inch

journal

is

increased

above 6"

in

diameter.

The their

Gibs.

thickness

The at

t

height of the gibs (G) should be

should

be equal

to

\,

of

the

f,

and

shaft

diameter. Instead of using three adjusting Adjusting-wedges. as in and screws, Fig. 280, another arrangement is to wedges

DRAWING AND DESIGNING. use one wedge and one adjusting-screw with two guide-pins, as in Fig. 282.

ports the gib and

The

In the latter arrangement the wedge supis

in contact

with the frame

its

entire length.

thickness of the wedges at the top should be

the diameter of the screw (A)

+ i",

I

and their width

.

J times

w when

282.

FIG. 280.

three are used should not be less than % the length of the

journal (L). in

6 to

I

in

The taper of The screw 8.

enter the wedge

wedge

is full

W

a.

the wedges

A

may

be made from

I

should be sufficiently long to

distance equal to

its

diameter when the

down.

Top and Bottom Blocks. The thickness t nest part of the bottom block should be equal

at the thin-

to .23,

that of the top block .15, of the journal diameter.

and

ENGINE. DETAILS.

Design a crank-shaft bearing of the form

Exercise 137.

shown

in

proportioned for a horizontal steam-

279,

Fig.

357

v-,

engine, having a cylinder 9" in diameter, stroke 10",

steam-pressure 200

Ibs.

initial

per square inch, and the diameter of

The bearing to have a vertical and horiShow a HALF ELEVATION, A HALF zontal adjustment SECTIONAL ELEVATION, a HALF END VIEW, a HALF SECTIONAL the journal (D) 4".

of f".

HALF PLAN, and a HALF SECTIONAL PLAN Scale 8" to the foot. right-hand side.

END VIEW, the

a

Exercise 138.

shown

in

Design a crank-shaft bearing of the form proportioned for a horizontal steam-

280,

Fig.

engine having a cylinder 18"

and an

The

in

diameter, stroke 30" long,

steam-pressure of 220

initial

Ibs.

per square inch.

bearing to have a horizontal adjustment of

direction and

of

a vertical

in either

J"

Make

adjustment of $".

D

the

diameter of the journal 9".

Show

an ELEVATION, PART PLAN, and PART SECTIONAL

PLAN, the plane of section journal.

Show

Scale

centre of

the foot.

drawing of the adjusting screws and Scale 8" to the foot. Fig. 281.

also a detail

wedges, as

in

Exercise

shown

4." to

the

passing through

Design a crank-shaft bearing

139

in Fig. 280, substituting the

ment shown

in

Fig. 282.

Make

form

adjusting-wedge arrangethe

for the conditions given in Exercise 138.

Ball Bearings

of the

proportions Scale

This device for reducing

4." to

suitable the foot.

friction consists

between the journal and the beartaking the place of the bush in supporting the

of perfect spheres placed

ing; the balls

shaft, thus substituting rolling for sliding friction.

As

the

bearing areas are only slightly flattened points, the wear will

DRAWING AND DESIGNING. be comparatively rapid so, to reduce the amount to a minimum, the balls and the surfaces upon which they roll ;

made of steel tempered as hard as possible. The different forms of ball bearings are designated ing to ;he number of points that the balls have in are

with the surfaces upon which they

points

contact

roll.

drawn through one

In a three-point bearing a line in

accord-

of the

the direction in which the load acts should pass

midway between bearing shown

the other two points.

in Fig.

283

will give

Thus the form

good

results only

the resultant of all the pressures acts at an angle of

45,

of

when other-

wise the balls will not revolve on a true axis, but will have a

screw motion and therefore a considerable amount of

The

design shown in Fig. 284

is

friction.

suitable for a pressure in a

In a four-point bearing a line drawn

vertical direction only.

through one of the points

in

the direction in which the pres-

sure acts should pass through a contact-point on the other side of the ball (as in Fig. 285), then the balls revolve on a true axis and sliding friction

Size of Balls.

is

entirely avoided.

Steel balls rolling under pressure

do not

by crushing, their period of usefulness depending upon both speed and pressure. This would seem to indicate that

fail

the balls should be as large as possible, thus reducing the

number

of revolutions in proportion to those of the shaft,

increasing their strength

owing

;

but there

is

and

a practical limit to this

to the fact that the larger the balls the fewer will be

the number, and therefore the fewer the number of bearing points.

The bearing would then

fail

upon which they

roll.

into the surfaces

by the balls crushing There is a great di-

versity of opinion as to the proper size of ball in relation to

ENGINE DETAILS. load and speed.

The

size

given in Table No. 37 gives a

359 fair

average proportion of the diameter of the ball to the diameter of shaft used in practice for horizontal bearings.

TABLE NO. Shaf* 'Jiam.

37.

DRAWING AND DESIGNING.

30-

No

supposing that formula increase D

l

4 gives n

to get in the next whole

Taking n

=

21,

we can

find

/>,=

=

we must

20.75, then

number

of balls.

D^ by the formula

d+e I

So

01

(5)

sin

Load on Bearings. bearing

is

As

already explained, the

a function of both speed and load. FIG. 283.

FIG. 284.

life

of a

Therefore

if

FIG. 286.

FIG. 285.

the speed

is

increased, the load

creased or the

life

must be corresponding!]/ de-

of the bearing will be shortened.

the proportion of ball to the shaft diameter given

in

Using Table

ENGINE DETAILS..

361

37, the safe load in relation to the speed

may be found by

the formula c X __f-

where*

L =

f = e

=

5

total load

N (6)

,

on the bearing;

strength of ball;

speed of the ball races in feet per minute

N=

number

of balls carrying the load

bearings =

i of the total

;

;

in horizontal

number.

Exercise 140

Design a lathe grinder of the form shown 286 in *Fig. Make provided with four-point ball bearings. the emery-wheel 6" in diameter xi" thick, belt drum ij" in diameter and length suitable for a ij" of the shaft

Show shown

The diameter

an ELEVATION with one of the bearings partly in

HALF END VIEW and

section, a

as

belt.

(D) = f ".

in Fig. 286.

a

HALF SECTIONAL END VIEW

Scale twice full size.

Thrust Bearings._The

difficulty

experienced with the

ordinary pivot or thrust bearing, due to the velocity increasing as the distance from the centre, is overcome by the application of balls to

this

type of bearing.

The

designs

Figs. 287 and 288 are made by the Boston Ball Bearing Co. and may be used on either vertical or horizontal

shown

shafts.

in

The

balls are held in place

by the cage

C, the use of

which, although tending to increase rather than diminish tion, facilitates the placing its

and by various distances from the

and removing of the

use the balls can be placed at

fric-

balls,

centre cf the shaft, thus increasing the time the bearing will *un before

wearing grooves

in

the plates

PB.

In Fig. 288

DRAWING AND DESIGNING.

362

the balls are arranged in spirals

;

thus every ball runs on a

separate path, and the tendency to wear grooves is reduced to The small cages are made in one piece, as in a minimum. Fig. 287, and the balls are put into position cage, while in the large cages the side,

The

by

top

is

by springing the

fastened to the under

288

rivets, after the balls are in position, as in Fig.

cages are

should not be

made from -y" less

to

"

thick.

The

the diameter of the

than

thickness

(t)

and the

ball,

DR

FIG. 287.

FIG. 288.

distance e should not be less than

The

of the ball diameter.

centres of the ball races are J of a ball diameter apart.

.The hub

H

is

screwed to the shaft by means of one or more

set-screws (5), the diameter of which

not greater than

D' or over.

2D when The

".

D

L= is

less

2t

-f-

may be made

.2D, but

3^, but not less than %D.

than 2", and

=

1.7

when

D

is

load and speed to which this type of bearing

subjected will determine the

number

of balls.

2" is

Taking the size

ENGINE DETAILS. of ball in proportion to the diameter of the shaft from

Table

No. 37, then from formula No. 6

Design a thrust bearing of the form shown Fig. '287 for a 4" shaft, to carry a load of 760 Ibs. and run a speed of 600 revolutions per minute. Scale full size. Exercise 141.

m at

Stuffing-boxes.

To

prevent

leakage,

through the walls of a chamber containing passed through a cavity

filled

when fluid,

rods

work

the rod

is

with an elastic material which

any irregularities on the surface of the Fig. 289 shows a stuffing-box suitable for a horizontal

will adjust itself to

rod.

DR FIG. 289.

steam-engine piston-rod, and Fig. 290 one arranged for a vertical steam-engine piston-rod.

The stuffing-box SB may be made a separate piece and bolted to the cylinder-head, as in Fig. 289, or cast with the cylinder-head, as in Fig. 290.

Part of the

box

SB

is

bored

DRAWING AND DESIGNING.

FIG. 290.

ENGINE DETAILS.,

365

PR, thus leaving

larger than the diameter of the piston-rod

space

S around

the rod which

is filled

with packing consisting

The

of a fibrous material saturated with oil or tallow.

ing

is

which

as

eter,

down

pressed against the rod by screwing is

generally in

made

a

of brass for rods

pack-

the gland G,

under 4"

in

diam-

Fig. 289, and of cast iron lined with brass for

the larger rods, as in Fig. 290.

The proportions

Proportions.

of

the

stuffing-box

generally decided by the conditions under which

thus the box

is

is

used

longer for a high than a

;

low

However, under any conditions, the longer the

pressure.

box the longer

The

generally

made

it

are

will the

last.

packing

following proportions are suitable for average pres-

sures and speeds, and could be used for high pressure, but

would require

to be repacked comparatively often

L = 2D for rods 2" or less in L = \\D for rods between 2" T

__ jl/}

L= D /,

=

C=

+

<<

<<

<<

.75^;

and 3"

//

T'= ^D

<<

A

ff

in

diameter;

''

4<

in nearest -fa;

=Z

\\D-\-2d;

= d' = /,

2D-,

Exercise 142. is

diameter;

\" for rods over 4" in diameter;

/=
R=

3

:

Draw

<*;

from f " to f'V

a stuffing-box, in which soft packing

to be used, for a horizontal-engine piston-rod (Fig. 289).

Make

D=

if" in diameter.

Exercise 143.

Draw

Scale full size.

a stuffing-box (Fig. 290), in which

DKAWING AND DESIGNING.

366 soft

packing

to be used, for the H.-P. cylinder of a vertical

is

D = 4".

Make

steam-engine.

Thickness of cylinder-covet

Scale 8" to the foot.

li".

Metallic Packing.

designs of metallic packings

Many

have been devised to replace the

most successful

A

Packing.

that

is

known

soft packings.

as the

One

of the

United States Metallic

design showing the application of this form of

packing suitable for high-pressure steam-engine piston-rods is shown in Fig. 291. This form is known as the ''double

packing" and

is

packing arranged is

shown

in

practically in

two

tandem.

sets of the ordinary

form of

In Fig. 291 the back packing

section and the front

partly in

section.

The

packing consists of babbitt-metal rings A, B, and C which are cut in halves and forced into the cup by the spiral

H

spring S.

On

the packing nearer the cylinder the spring

The

rings

A, B, and

C

are conical,

the correspondingly shaped cup //,

the

flat

face of

joint with is

turn

the ring R,

on the

free to slide is

free to rock

or preventer P'

flat

it

.

As

face of the ring R,

on the casing

binds the rod nor constrains

H rests

against

which forms a ball-and-socket

G

the outer casing

and being forced into the cup-rings close and

The cup

PR.

press against the piston-rod

H

S

be aided by the steam- pressure acting on the follower F.

will

in

G

the cup

which

in

or P', the packing never

any way.

The packing

is

prevented from drawing back with the rod (beyond a small movement) by the flange on the follower Scorning in contact with the preventer Exercise 144 Metallic Packing

P or P' Draw

shown

.

the

arrangement of United States

in Fig.

291.

Scale full size.

ENGINE DETAILS.

aims

367

A.

B&CMAOC.

IH HALVES

VtlTH

k

CUT OUT

SPRINGS 4-h OUTSIDE DUMB

4 COHS

D. R.

FIG. 291.

DRAWING AND DESIGNING.

3 68

When

Cross-heads and Guides.

the connecting-rod

inclined toward the direction in which the piston will exert

is

is

moving

it

an upward or downward pressure according to the

direction in which the engine

is

running, and, unless special

means are employed, would tend to bend the piston-rod or force

it

out of

its

straight path.

rence the piston-rod end

is

To

prevent such an occur-

provided with a cross-head which

R FIG. 292.

slides

on surfaces that are

parallel

with the piston-rod, called

guides.

Cross-head Blocks.

Assuming

that steam

not cut

is

off

before midstroke, then the thrust caused by the obliquity of the connecting-rod will reach a

maximum when

nearly at right angles with the Hne

Taking

BO

the crank

(Fig. 292).

L =

load on piston

R=

thrust of the connecting-rod;

;

/ '= steam-pressure per square inch; /'

=

'V= A =

intensity of pressure per square inch

velocity of cross-head in feet per

;

minute;

area of the bearing-surface in square inches,

then

L:R'.\BO:AO.

is

ENGINE DETA ILS. /vV

3&Q Jp

Therefore

= LX AO -7^ = L X BO~ Taking the length

of the crank

AO - AO

VBO*

OA

'

9

as the unit, then

nd*

where n

= ratio

of connecting-rod to crank.

Pressure on Rubbing-surfaces.

It varies,

from 22 to 500

ties,

*>'

40000

=

y

,

may

engines

diver-

great

according to the different authori-

Ibs.

and that

is

proper intensity of pressure on the

sity of opinion as to the

guide-blocks.

There

Thurston gives

per square inch.

this value

in

marine and stationary

be exceeded to the extent that p'

=

60000

-f-

V.

Then

,_ R

nd* -*>*r *v

40000 In

many on

cases

of

40000 (Vn*

ordinary

i)"

stationary-engine

practice,

having four-bar guides, the above formula would give a very short block, and as there is generespecially

ally

no

engines

difficulty in

providing large rubbing-surfaces,

we

find

the areas increased as large as

where V'= velocity stroke

X

The

twice the

of piston in feet per

number

minute

=

(length of

of revolutions per minute).

cross-head should always be designed

so that the

DRAWING IND DESIGNING.

37

resultant pressure (K) on the guides will have its point of resistance at the centre of the cross-head rubbing-surfaces, as

shown

in Fig. 292.

"Wrist-pin.

The connecting-rod

is

attached to the cross-

In this form of joint, as the head by the pin CP, Fig. 293. velocity is low and the pressure constantly changing in direction and magnitude, the allowable pressure per square inch is in

comparatively high, reaching

some designs

much

as

as

Seaton says that the pressure per square inch should never exceed 1200 Ibs. per square inch of Ibs.

1400

per square inch.

projected area (d

When

X

/)

the total load on the pin

load on the piston,

the

i.e.,

initial

piston, the length of the pin

d

to

i

.

is

is

taken as the

steam-pressure

generally

made

maximum

X

area of

to equal from

3
Taking the length

/

=

d,

then

-v? When

the length of the pin

is

made equal

to | of its diameter,

then -

fflfl

**i/. V P

:

Taking the value of/'

=

1200, then

d=. VL+-40

A pin

and

/= VL ~

30.

.

.

(10)

proportioned to either of the above formulae will be

amply strong

to resist bending.

Guide-bars.

When

the guiding-surfaces are part of the

frame the guides are bored and the bearing-surfaces on the This arrangement cross-head are turned as in Fig. 297.

ENGINE DETAILS.

37*

DRAWING AND DESIGNING.

372

reduces the number of parts, which designing, as

When made

liability to error in fitting up. flat,

T

of rect-

section (when of cast iron).

prevent the formation of ridges, due to the travel of

the cross-head varying as the wear on the joints

in

separate the bear-

and the guide-bars are generally

angular (when of steel) or

To

always a good point

not only decreases the labor but also the

it

ing-surfaces are

is

is

connecting-rod

taken up, grooves are cut across the bars over which

the ends of the cross-head blocks (CB) project at the end of

each stroke.

The

Strength of Guides. occurs

when

the cross-head r> T

bending moment

bending = fZ. Table No. 29. to the stroke

nearly at the centre.

Z

is

the modulus of section, given in

distance-pieces

the length of the block

which may be made Four-bar Guide.

=

the

and the moment of resistance to

of Guide-bars between

-f-

Then

f

= -^

Where

The Length

=

is

is

greatest pressure on the bars

-f-

is

end clearance,

i" at each end.

The arrangement shown

that used on the cycloidal engine (Atlas

in Fig.

293

is

Engine Works).

ENGINE DETAILS,

373

guide-bars G. The piston-rod PR is secured to the crosshead C by the arrangement shown in Fig. 294. To prevent t"ne

the piston-rod from exerting undue pressure on the stuffingboxes, should the axis of the piston-rod not coincide with that of the cross-head,

head

is

which

made

the hole through the shank of the crosspiston-rod,

means

adjustable and held in position by

is

of the set-

In this arrangement the breadth b of the bearing-

screws 5.

surfaces on each bar

The

the diameter of the

larger than

is

generally

made

area of the bearing-surfaces

formula No.

8.

equal to ^ their length.

be determined by

may

Then and

1'

=

.

b

4

The form

of guide-bar used in this design

may be made

of

cast iron or steel, and proportioned in the following manner: Having determined the breadth b and the length Z,

then calculating for a bar of rectangular section, secured at both ends and loaded at the centre, the height h of the bar at the centre will be found by the equation

from which

JR X L' X 6 b X/X 6' where

/ may

Take (h

x

b)

Then the web -T- 4#.

h'

be taken at 3000 for cast

=

.?$

h,

iron,

and 6000

for steel.

web

be

then the area of the

(h'Xb), and taking the thickness

height of the

web

t

of the

will

web

=

=

.4^.

at the centre will equal area of

DRAWING AND DESIGNING

374

The

B

greatest strain on the stud-bolts

guides to the engine-frame

=

be made

i

J"

is

due to screwing up.

To

diameter.

in

which secure the

They may

allow for any slight inac-

workmanship, the holes through the bars are made larger than the diameter of the bolts B, and the bars are

curacy of

y

T

adjusted laterally by the screw vertically is

screwed into

faces are lubricated

The

bars.

holes

O

oil

5'.

The

N, shown the guide-bar blocks GB.

by means

is

of the nut

by oil-cups screwed on

bars are adjusted in Fig.

295

>

which

The

rubbing-sur-

to the

upper guide-

transmitted to the lower bars through the

on the cross-head.

Draw

Exercise 145,

the four-bar guide and cross-head

arrangement shown in Fig. 293 suitable for an engine having a cylinder 12" in diameter X 15" stroke. Initial steam-pressure 75

per square inch.

Ibs.

Speed 300 revolutions per

minute, and a connecting-rod four times the length of the crank.

Scale 4" to the foot.

Draw

also details of the adjusting-nut TV

and the

cross-

head pin, and show the arrangement of fastening the pistonrod to the cross-head, taking the diameter of the piston-rod

=

2".

Scale full size.

Two-bar Guide.

When two

arranged either one above

guide-bars are used they are

and one below the piston-rod

this case a cross-head of the

type shown

or both guide-bars above the piston as

The

latter

arrangement

is

in Fig.

297

shown

in

one commonly used

in

is

(in

used)

Fig. 296.

locomotive

construction.

The pressure

on the upper guide, L7G, when the locomotive is running forward, and on the lower guide, LG, when running back and as the engine is generally run forward more ;

is

E1V&INE DETAILS.

375

DRAWING AND DESIGNING. than back, the bearing-surface on the lower bar

may

be made

smaller than that of the upper.

C is of

In this design the cross-head

SB

with a brass slide-block

To

top and bottom.

fit

which has

it is

down

the bolts

cured by driving a tapered cotter through

The The

O

it

CB

in

is

and

and the

se-

cross-

to allow for lubricating the cross-head pin.

is

GB

guide-blocks

are fastened to the cylinder at one

end and to a guide-bar frame

Draw the

Exercise 146.

Also

easily

^

hole

ment shown

metal

strips of babbitt

cut and, after .the rod

is

gripped by screwing

head .shank,

and provided

and remove the piston-rod

from the cross-head, the -shank position,

cast steel

in Fig.

of

details

296.

at the other.

cross-head and guide-bar arrange-

Scale

3"

to the foot.

the 'slide-blocks

cross-head pin CP, cotter C,

SB, guide-block GB, and washer W. Scale half size.

Adjustments to take up the wear or

Cross-heads.

for

original setting may be accomplished by moving the guidebars, as in Figs. 293 and 296, or the slide-blocks, as in Fig.

297. In this design the cross-head

C

is

hollowed to receive the

connecting-rod end, which works upon the pin CP. is

of case-hardened steel

and

is

The

pin

kept from turning by the

screw K. ^-inch square-headed

The

piston-rod

cured by the nut

screwed has

flat

PR

is

LN.

screwed into the cross-head and

The

socket into which the rod

surfaces on the top

and bottom to give

se-

PR

is

clear-

ance 'for the mit N.

The diameter

at the

end of the socket

is

equal to the

dis-

ENGINE DETAILS.

377

DRAWING AND DESIGNING.

3/'8

tance across the

flats,

and tapers back

j-

of an inch to the

larger diameter.

The

bearing-surfaces on the slide-blocks are turned, and

the corresponding surfaces on the frame, upon which they are bored to the

same

radius.

The

grooves on the under sides, which

fit,

blocks are provided with

over projections on the

fit

top of the cross-head, to prevent their lateral movement. To take up the wear, the slide-blocks move horizontally, on the inclined surfaces

upon the top and bottom

distance equal to

for a

of the cross-head,

the length of the holes minus the

diameter of the studs, and by this horizontal motion they

move

vertically T^ of an inch.

l)raw a cross-head of the form shown

Exercise 147.

in

showing a SIDE ELEVATION, END ELEVATION PARTLY IN SECTION, and a SECTIONAL PLAN, the plane of Fig.

297,

section passing

through the centre of the cross-head pin.

Scale full size.

To

Construction.

find the inclination necessary to give

the required vertical movement,

mark

off

ab the distance from the centre of the pin

and through

C draw

on the centre

CP to

line

the point C,

the line cd at right angles to ab and

equal to the horizontal motion of the slide-blocks, and through d draw de equal to the vertical movement.

The

line

drawn through the points

ce will

have the required

inclination.

Fig. 298 shows a form of cross-head used on the cruiser

In this design the wrist-pin

Olympia.

of the cross-head,

C by

S.

outside

and there are two bearing-surfaces on the

connecting-rod end. cross-head

CP is

U.

The

slide-blocks

the bolts B.

To

SB

are secured to the

allow the removal of the

ENGINE DETAILS. slide-blocks while the cross-head

jecting lips

L

the bolts B.

is

379

in position,

one of the pro-

removable and held

on each block

is

To

the removal of the Apiece Z,

'facilitate

in place

by

it is

provided with set-screws 5. The piston-rod PR is secured to the cross-head by the nut shown in Fig. 67, page 100. Fig. 299

is

an isometric sketch of the complete cross-

head. Fro. 299.

/2/faa

FIG. 298.

Exercise 148.

head shown PLAN, and a

Draw

a general arrangement of the cross-

Show a FRONT ELEVATION, a HALF HALF SECTIONAL PLAN of the top, the plane of

in Fig. 299.

section passing through the centre of the wrist-pin.

Scale

4.

inches to the foot.

Eccentrics.

The

the radius of crank-pin

eccentric is

is

a form of crank in which

greater than the

the crank and the shaft, as

shown

sum

in Fig.

of the radii of

300, where the

DRAWING AND DESIGNING.

380 crank

is

shown by dotted

lines,

and the eccentric by

full lines.

used for converting circular into reciprocating motion. It For this purpose its action is identical with that of a crank, is

and as the eccentric absorbs rnore power than the crank (owing to the greater leverage at which the friction acts) it is

used

in preference

only where the throw

is

comparatively

FIG. 300.

short.

The

eccentricity

or

throw of the eccentric

is

the

distance r from the centre of the shaft to the centre of the

sheave.

The

the eccentric Fig. 301

stroke of the reciprocating piece worked

is

by

equal to twice the throw.

represents an

slide-valve of a locomotive engine.

generally called the sheave

used

eccentric

o**

The

pulley.

passed on to position over the end of the

for

working the

eccentric proper

When

it

is

cannot be

shaft, the sheave

is

ENGINE DETAILS.

P and P

381

f

parted on a line passing through the centre of the shaft and at right angles to the horizontal

made

in

two

parts,

,

centre line of the eccentric, and held together by studs.

the strain

may come on

That

the stronger part, P', the key and set-

screws used in fastening the sheave to the shaft are placed on that part.

The

eccentric-rod

ER

is

secured to the strap

5 by

DRA WTNG AND DESIGNING.

382 the bolts

B,B^B

centre-bolt B^

when

,

is

Z

The

hole through

elongated that the rod

the

strap,

ER

may

the

sheave

the

for

be adjusted

setting the valve.

The

Proportions.

\D

",

then

will

.

with a

thickness

minimum

= D + 27- + 2t.

of \"

of

/

The diameter

.

The breadth

B of

may be

of the sheave

the sheave

may

be found by the formula

B= where

L= D'

p

=

load driven

x/

by the eccentric

allowable pressure per square inch of projected

t

which should have a

= iD. = ij times

Thickness of key

Breadth of key

maximum

of 100 Ibs.

.

size of the strap-bolts

resist the load

the thickness.

SB

should be proportioned to

driven by the eccentric.

~ X where

;

diameter of the sheave;

f = area,

The

L D'

2

X

/,

= diameter at the bottom of the threads L = load driven by the eccentric = safe strength of bolts, which may be taken ft

d

l

;

;

Ibs.

The

at

2000

per square inch.

size of the rod-bolts,

the two fitted bolts,

may

*.

assuming the load is resisted by be found by the formula

L

'

4

X2X/

ENGINE DETAILS.

f

may be

C between The

383

taken at 3000 for wrought iron.

centres

may be made

parts marked

=

The

distance

$d.

in

decimals are proportional to B, the

Draw

the arrangement of eccentric-sheave

breadth. Exercise 149.

and strap shown

2300 area

Ib's.,

=

50

in Fig. 301,

taking the pressure per square inch of projected Ibs.

Draw the views shown VIEW looking' towards the through the eccentric 3i"

X

proportioned to carry a load of

i".

in Fig.

301

;

also a

SECTIONAL END

right, the plane of section passing

at the line cd.

Scale half size.

Make

the eccentric-rod

COURSE

II.

ELEMENTARY MACHINE DRAWING INCLUDING

WORKING AND ASSEMBLY DRAWINGS, CONVENTIONS FOR DIMENSIONING, INDICATING FINISH, NOTES, BILL OF MATERIAL, TITLE, STYLE OF LETTERING, ETC.

DETAIL

Prerequisites

before Beginning Course

have completed Course I as contained

II.

Students must

in Reid's

Mechanical

Drawing, or an equivalent course consisting of Lettering, Geometrical Drawing, tersections,

Orthographic Projection, Developments, In-

Isometrical

Drawing and

W orking T

Drawing.

ELEMENTARY MACHINE DRAWING. MINIMUM NUMBER OF PLATES AND MAXIMUM NUMBER OF HOURS ALLOWED TO COMPLETE EACH DIVISION OF THE WORK. FIRST SEMESTER. PLATES

i

AND

Consisting of screws,

2.

and

bolts, rivets

riveting

must be completed and handed in on or before Friday, October 9, 1908. (26 hours.) PLATES 3, 4, AND 5. Consisting of anchor bolt and locking and

bolt fastenings,

devices, knuckle

and

be finished according to before Friday,

PLATES 6 AND

7.

and shaft couplings, must directions and handed in on or

cotter joints,

November

20, 1908.

(36 hours.)

Consisting of universal shaft coupling

and

pipe couplings, must be finished and handed in on or before Friday,

December

PLATES 8 AND

9.

18, 1908.

must be finished and handed uary

29, 1909.

(24 hours.)

Consisting of post bearing

and

in not later

pedestal bearing,

than Friday, Jan-

(24 hours.)

Students failing to finish any of the divisions of the work within

the time specified, because of excused absences,

make arrangements with

the Instructor to

work

in

may

one or more

extra periods.

Students doing more work than will,

is

required in the given time

other things being equal, receive a higher mark.

END OF

FIRST SEMESTER. 387

DRAWING AND DESIGNING.

388

NOTE. Registered Freshmen conditioned in Machine Drawing will be required to complete satisfactorily the following plates of this course in addition to the plate shown in Fig. 302 i, 2, 5, :

and

according to the directions given in the text. Conditioned students must work at least six hours per week. When the above plates are finished, work on the regular Freshman Machine Drawing may be commenced.

8, 10,

13,

SECOND SEMESTER. PLATE

10.

Consisting of pulley and spur gear, must be completed

and handed

in

on or before Friday,

February

19,

1909.

(15 hours.)

n

PLATES

AND

Consisting of disk valves and globe valve,

12.

must be finished and handed

13.

Consisting of marine cross-head, must be finished on

or before April

PLATES in

13

on or before Friday, March

(21 hours.)

19, 1909.

PLATE

in

AND

14.

on or before

9,

1909.

These

May

(18 hours.) plates

21, 1909.

must be finished and handed (36 hours.)

Students failing to complete any of the divisions of the work satisfactorily

within the time allowed

make arrangements with

(for

the Instructor to

good reasons) may in one or more

work

extra periods.

Students doing more than the required amount of work in the given time will receive a higher mark, other things being equal.

END OF SECOND SEMESTER.

ELEMENTARY MACHINE DRAWING.

STUDENTS' CONDUCT IN CLASS. Students will be expected to give

drawing work during the full time

//V

TWO /V;r />* ftAD//

fT MflK WCSS TO

B.

/NO/GATE O

By

G/^e\f //V /?

FT

/A/

/NCHES

strict

of each

/<

attention

their

to

drawing period.

THUS O/MEHS/OHS Of Z^T-SS 7^4/ ) THUS - A/Or THUS

COMPLETE 0/A

,k !r

<*1-

fcl

:#

/*r

^-Kr A r|^^

Materials and instruments must not be put away until the

warning

bell rings.

Nothing should be brought to the drawing table that needed for the drawing work in hand. If a student expects to

is

.not

be absent from the class he should

endeavor to get excused by the Instructor and make arrangements for making up the work.

DRAWING AND DESIGNING.

390

A

student coming late to class should report at once to the

he will be

otherwise

Instructor,

marked with an unexcused

absence.

A

report from the Instructor concerning the deportment of

each student in class

is

expected by the

Dean

two

every

months.

When

a student

is

absent from class through an unforeseen

cause, he should at the next regular period

fill

blank, giving date and cause of absence, sign

it,

out an absence

and hand

to the

Instructor.

The work ment with

PLATE

of

all

absent periods must be

made up by

arrange-

the Instructor. Fig. 35, Exs. 29,

i.

page 131, 32, page 142, and

4,

page 58. This plate should be laid out similarly to that shown on page 391. See Fig. 304 for standard bill of material. Dimensions for standard title are given in Fig. 304.

Use a 6 and draw

H

pencil sharpened to a long wedge-shaped point

the figures with fine light lines, beginning at the upper

left-hand corner of the sheet.

In planning the positions of the

different exercises take into account the space required for the title

and the

pleted

bill of

material.

in fine pencil lines

All the exercises should be

and submitted

approval, after which the drawing

is

be cleaned and

to

com-

to the Instructor for all

the

given and required lines are to be relined in strong lines with

a 4

H

pencil sharpened to a long conical point, not too sharp.

The dimension

lines

may now be

placed to the best advantage,

using a fine sharp line drawn with the 6

H

be taken when locating dimensions never of a line or even too near a line

when

it

pencil.

Care should

to place figures

can be avoided.

on top

The

dimensions should stand out on the clear paper to avoid con-

ELEMENTARY MACHINE DRAWING. fusion.

and

Great care should be taken in pencilling in the

bill of

material to see that

The above

it is

391 title

neatly and correctly lettered.

directions will apply to the pencilling of all draw-

ings in this course.

Plate

i

will

be a finished pencil drawing,

DRAWING AND DESIGNING.

39 2

and only the line are to

title

and

bill

be one thirty-second of an

PLATE plate

is

to

2.

Exs.

of material together with the border

The width

be inked.

9,

10,

of the inked border line should

inch.

n,

12,

and

13,

pages 70 to 77.

be finished in pencil as in Plate

i,

This

and when signed

ELEMENTARY MACHINE DRAWING. PLATE is

to

3.

Exs. 17 and 22,

be finished

in pencil

only.

393

pages 85 and 104.

Read

the

text

This plate

carefully, de-

scribing the different kinds of foundation bolts, viz., the rag

the Lewis

bolt,

and the anchor

bolt.

Study

also

the

bolt,

require-

DRAWING AND DESIGNING.

394

ments of the problems and the given data. the drawing for Ex.

Before commencing

student should study the text de-

22 the

Locate the

scribing the different styles of nut-locking devices.

drawing

for Ex. 22 in the

upper right-hand corner of the sheet

and use only half of the plan shown. In Ex. 17 assume D the diameter of the washer

draw

at

6J" and

to scale given.

PLATE

4.

Exs. 23, 24, and 26, pages 108 and 120.

Use only

made

Finish in

Fig. 84 of Ex. 26.

Joints to be

of

iron.

wrought

pencil.

PLATE

Exs. 44 and 50, pages

5.

place the longitudinal elevation at

left

167 and

end of sheet and the end

elevation to the right of the front elevation and

above the

In Ex. 44

178.

draw

latter, showing the upper half removed.

also a plan

Make

square

key J of the diameter of the shaft. In Ex. 50 assume

D

at 17^".

This plate

is

to

be finished in

pencil and traced.

Page 185. Make detail working drawAll the parts are to be separated and fully dimensioned.

PLATE ing.

Ex. 53.

6.

Finish in pencil.

PLATE

Exs. 56, 58, and 64, pages 191,

7.

In Exs. 56 and 58 elevations

and

Make

the inside diameter of pipe 6".

sections for all three problems the

Make

in Ex. 55.

make

and 202.

194,

finished pencil

drawing with

same

title

as given

and

bill of

material as usual.

PLATE

8.

Exs. 70 and 109, pages 214 and 304.

225 in the latter exercise. in

the

Make print.

text-book, finished

show a

pencil

Use

Fig.

In addition to the two views given plan

drawing

above

and

the

trace

main on

elevation.

cloth.

Blue

ELEMENTARY MACHINE DRAWING. PLATE all

9,

Make

Ex. 76, page 232.

detail

drawing showing

necessary views of each part of the problem. Scale

pencil drawing.

PLATE

4" = i

pulley 20", width of belt 3^".

Make

ft.

PLATE n.

Make

Diam.

Scale

finished

Exs. 99, 101,

:

In Ex. 84

of shaft 2"', diam. of

6" = i

In Ex. 92

ft.

make

pencil drawing and trace on cloth. and 103, pages 285, 288 and 292.

finished pencil drawings as directed.

PLATE

12.

on each.

detail

assembly views, half section

assembly draw-

and half elevation

Next take the valve apart and make working draw-

ings of each part.

PLATE

Make

Ex. 104, page 292.

Draw two

ing.

finished

ft.

assume the following dimensions

scale

Make

Exs. 84 and 92, pages 247 and 269.

10.

4" = !

395

13.

Scale as given.

Ex.

147,

page 378.

shown draw a longitudinal

In addition to the views

cross-section.

Finish in pencil and

trace.

PLATE

14.

Ex.

working drawing and

PLATE

15.

Ex.

trace.

133,

Make

page 338.

130,

a complete detail

Scale to suit.

Make

page 339.

assembly drawing

as directed, also details of each part fully dimensioned.

Finish

in pencil.

PLATE drawing.

15 A.

Ex.

149,

Finish in pencil.

page

383.

Scale to

suit.

Make

deta'il

working

COURSE

III.

ELEMENTARY MACHINE DRAWING FRESHMAN

In Mechanical Drawing, Course

PREREQUISITES. i

to

6

inclusive,

10,

u,

Machine Drawing, Course together with Plates will

be required of

Student

i, 2, 5,

all

Conduct

given on page 389,

YEAR.

14,

12,

II, the

8 and 10.

Class.

19,

I,

Plates

22.

In

drawing shown on page 389,

students before in

17,

and

21

The above,

or

its

equivalent,

commencing Course

Read

carefully

the

III.

directions

COURSE

III.

ELEMENTARY MACHINE DRAWING. MINIMUM NUMBER OF PLATES AND MAXIMUM NUMBER OF HOURS ALLOWED TO COMPLETE EACH DIVISION OF THE WORK. FIRST SEMESTER.

PLATES 1-6 INCLUSIVE.

Consisting of freehand lettering; must

be completed and handed in on or before October i6th. (26 hours.) All lettering in regular periods will then stop

work

PIATE

Machine Drawing will begin. Must be finished according to

7.

than October 3oth.

in not later

PLATES 8 AND later

Must be

9.

December 12

AND

13.

January i5th.

PLATE

14.

2Ojth.

To

and handed

(12 hours.)

and handed

in not

(12 hours.)

Must be handed

i8th.

directions

finished as directed

than November i3th.

PLATES 10 AND n.

PLATES

and the

in

in

completed on or before

(27 hours.)

To

be finished and handed in not later than

(12 hours.)

be finished and handed in on or before January

(12 hours.) 399

400

DRAWING AND DESIGNING. Lettering, Fig.

305, page 400.

Use the 4

H

rpened to a long conical point, not too sharp.

x

X'

It

Locate the lower point of the first guide-line 12 squares from top and 7 squares from left-hand edge of cross-section pad.

ELEMENTARY MACHINE DRAWING.

401

downward

Guide-lines should.be sketched lightly with a stroke and allowed to remain

&*J,

N X *

Q

^ s?^

.

iy

N X ? b k (^ ^ ^? O ^ > ?! ^i>^ S < rv-

si

^

C2


^

!ir*u$

-s


||^&y 3 ^

rr

xT

S


i?

a

tf

13

I So

until letters are approved.

^ O

^

<: kj k:

^ ^ in

S - ^ a

)

r'V

hi

K v .7!

Si rt

K

^

IH

5 k

I

Q

^

N

O

fa

^^K S$ K

^^5 P^ hMS

i?

5'

*'L

drawing the guide-lines for the curved letters, analyze the lines of each curved letter, as given on the chart After

on the blackboard before attempting

to

draw the curves

DRAWING AND DESIGNING.

402

A

on the pad. curved

as

letter

obtained

before

close

very it

on

appears

draw

to

attempting

second

the

first

be

should

chart

the

the

of

approximation

curved

letter.

Do not copy the letters or figures on form and proportions

correct

pages 400 and 404, the

for all the letters

must be obtained by a careful study The work on all the letters and

and

figures

of the chart. figures

must be

strictly

freehand.

Place at the bottom of each plate at the right-hand corner the following information:

Time taken

hours),

number, Section (days and plate, and Name, e.g., MON.

Plate

to finish

Time

The

Name.

and WED., 2-4, Plate

i.

height of

should be one square high and

these

letters

}

4

hours,

al

capitals.

PLATE

Freehand guide

2.

and

lines

figures higher than

until letters are

The same

must be drawn

to

-letters

approved.

care as to proportion

careful to balance letters

so that the

all

one square and allowed to remain

and form should be ob-

served in lettering this plate as in Plate

Be

for

same space

will

i.

and numbers on

all

plates

appear from both ends of

line

edge of pad.

The

small letters should be extended in width a

yond the proportion given

The open

letters

be-

for the larger letters.

should be spaced closely together and

words should have a squares.

little

liberal

space between them, say ij

ELEMENTARY MACHINE DRAWING.

403 *

l

k

| 5

K^'O

<

ll|

5 K

*lf *8< tafciu

>'**

l*lfvj ^t

*J^| \

x< < k ^

1

r&W**\A

lU^ ^ -j'

ij

|si|| ^ m .

SI

K SVS C

U? < > i 8U 8r \ %

S2S ^^

.41

Lit

iy

s8^ toUjiDrifl ? 1

UlK'g

jpo

I.

ft.

A ^\ ^fr ^^^xll^hi

^

i-ifl

ill

?J-

?>!"' Vs^U^ .v v'S b-

yi

vl Mlk IU^100^ SS

v

^

A*

to

!^S

i\ Q^J

Ij

N K ||

^

*$

HjR ^ T > NJ f

ft I,.

S ^S 1

Nl ff

^

<^ SSS^

^S Q:^

^ ^

5^

^^

* 5

,,J-

6 ^

r

i

^

i

"

X

^-i

^

P

I

-

fc

^^S

S^il i

M^?l| il^ ^V >^> lit Ux y-' |p |||ic 3j |p| |^ ^iOrs S^V h S g

fr

^^

111

fe

^

j^

in."

feft

^$r. s

^

>^ .1*

^|

.

';

Q-K^

^ U)

w Q:^^^^ | 1^5$: ^
*R

T

1^ x^

ca&K

8 US o
n

;

JK

'5

^L

8x <^S? ft^s

SI 5!<

IS ^\

HI

o,

404

DRAV/ING

AND

DESIGNING..

ftl

n

* x,'

,

^M^IHJ

^

K)

01 en Q,

>

*0 ^) Vj

to

^ to

,

C^m

^i^^SJ ^ j

Cyjfo^'^^a

^fo^^to^O) OQQQ K HI v\ Ch

vv

^

to

0) to

Q)

Q

h

00

ft)

^ ^ ^o to 9) Q > ^ to^O^ CHr ^V)^(oq) V)^ fNv v)Q\ A ) ^ 'o to ^) ^) M!

K

^

sm.

fK/^_

0) CM

^

C\t

fw

I

^^D^'Oto^^ ^ ^ ^0 (c Q ^ C\|

(V)

^

ro

C\i

)

01 oi

cu

^^ ^ ^ ^ ^ ^ ^ ^>

OQ

^

co

^

^0 Q)

ELEMENTARY MACHINE DRAWING.

405

Pencil three words only of the small letters at

first

and

submit for criticism before going on with the others.

for

PLATES

Use Ball pen, No. 506, to ink large small letters and figures.

3-6.

In the next three

letters

and No. 516

plates the directions for

letter

guide-lines, form, slope, spacing of letters,

and

for width of

small letters should be carefully observed.

PLATE drafting

6.*

rooms

While in the

a

substantial

majority

United States are

Capitals exclusively for notes and

titles,

there

using a combination of Gothic Capitals and

So

it is

deemed wise

to give the student

to introduce

of

the

leading

Gothic

in favor of using

are

number

a

Lower Case

one plate of Lower Case

some knowledge

letters.

letters

of their form, proportion

and construction. This plate should first be pencilled and after approval, inked. In addition to the "Ball" pen, No. 516, for large letters, the small letters should be inked with Gillott's No. 303.

when new should be "exercised" letter.

The form and

a

little

All pens

before beginning to

proportion of these letters as given by

the largest letters in Fig. 310,

on page 407, should be adhered

to as closely as possible.

In general these

letters

of a uniform pressure.

should be

The

made with down

strokes

only exceptions are the letters r

* All letters and figures should have uniform slope.

Letters

and

figures of

one square high should have a full half square slope. Each plate must be signed by Instructor in charge, jn ink

in pencil before inking and Plates not so signed will be rejected. plate is finished. plates are finished and signed they will be retained by the student until

when

When

on lettering are completed, binders and handed to the Instructor. the six plates

when they

are to be

bound with paper

DRAWING AND DESIGNING.

406

K

V*5

(0

\

q> 0)

.

*,*

*'<*

O^vLv

^ to ^

c$i

v O

v^ U

^

^

^

S'OKK

fX

ft\v

V\

i;

5

K.K IN

\Lw v Vv

(Krv\

N>

K

^^

^)

4)

1^.

K.

\Jfc

\{.

fX

MA

I

y

^

H)

M&

?

CQ |\^ f/v

">) ) ri

)

") l!l

5

^ KK KK

'fyw

^ Al ^\f^vj

x)

QQ

njft)

Qj

Or)

P)

QO)

^

")

CS)

"0 ") (*)

ft)

m

KK

KK KK

ELEMENTARY MACHINE DRAWING.

1

i

n '

**

407

3

^ 5

^

I

i

1 I *o

x?

^

i^ s

^ 45

^

I

f

1 t

fill

DRAWING AND DESIGNING.

408

and

u.

The curved

curved only

at the top.

*

I I ^

S

*

^ kju) <*:

*M

Vj

V)

0\

>

^

CQ

$ ^ > K

^

^S

$ Q

^

^ *

U

%

I <

v

N

U

^

r\

Or

(f\

111 ^ ^

Hj^

^^


X

..M

X $

v

0"

9 HI

^

J'

IV

^>$ '

T<0

trvi^^^N^MlU S S ^ i/ < Q 5 < Hi 2 S J L* a $ii oG

'M;iririfiP9 ^S :Sl^^io^^ ^r^s* 5 $

S^

s^u^Qr

*j-

*tt

x

^

^

Q

^^^

^

MUro

3

1 )

5

K

Ui


Hi

N

?

S

T

m

*

8 i ..?-*

i ^

f

fcS?

^ > ^ *

^>

$

KUib^S K ^ N ^

ij

^

I ^

IV

I & ^

<:

R

M

V

may be made with an up stroke The u is made with two down strokes

part of the r

Sp i .

i g

.

-Q-

^

N

^? ^li ^T io^^5 9S ^^^ ^S^S^^o^ioL N ^N>^< ^vsUiHjHi^S ?>;~

^

<&.

'(A

^^Q:

$

Hi

.^^^

^^ OC\^^

t

l

^^NlJ*

^IK^^I^^^^^^O^I!!

and the bottom curve

The m,

n,

filled in with a stroke to the right and upward. and h should be formed with nearly sharp upper curves.

ELEMENTARY MACHINE DRAWING. This plate

will

have

to

409

be repeated until the desired results

have been obtained.

PLATE 6A,

who may

students

This

Fig. 311.

an extra

is

lettering plate for those

finish the required plates

The

ahead of time.

extra plate will increase the grade mark.

PLATE Problem axle, as

Make working drawing

i.

shown

Problem

in Fig. 312,

shown

in Fig. 312,

right end view of bracket. Begin by laying off border

center lines of axle

as directed

drawings strengthen

Draw

all

on page

of all

Draw

are

Put

in

the drawing

by the Instructor, it Use the "dull" spring-bow pen.

is

will

title.

pencil,

H

sharpened

When

approved,

pencil, conical point.

all

and work down toward notes very carefully.

properly finished in pencil and signed

be ready

to

be traced on

cloth.

and begin tracing with the arcs of circles, circles and irregular

side of the cloth

Ink

all

any, before inking any straight lines.

curves

if

lines.

Ink arrow-heads and dimensions

in

Ink dimension

consecutive order,

thus: left-hand arrow-head, dimension, sign of inches,

hand arrow-head.

Locate

arrow-heads and dimensions,

Letter

the lower right-hand corner.

for

Project also

complete and

beginning at the upper left-hand corner

When

page 410.

fine, clear, clean cut lines.

and axle

lines.

top bracket for

for

line

the object lines with a 4

dimension

crank

automobile

and space and bracket. Use 6 H

8.

bracket

of

page 410.

Make working drawing

2.

planing machine as

all

7.

Ink hatch

For weight and character of

lines

and center

lines see

and

right-

lines last of all.

"Conventions," page 419.

4io

DRAWING AND DESIGNING.

ELEMENTARY MACHINE DRAWING

PLATE Problem

Make

i.

8.

a careful freehand sketch of either the

i|jj" drop hanger or the post hanger to be found room. Use orthographic projection and sketch on

H

411

in the drafting

8"X 10"

cross-

Use only one side of the paper. Sketch three views of body and detail of link. All dimensions notes, title, and finish marks must be neatly placed on sketch. section

.

pad with 4

pencil.

all

the center lines for the front

and end elevations and the plan.

Sketch center line for detail

Begin the sketch by drawing

Make

of link.

be

size of sketch to suit size of paper.

the lines

may

be strengthened.

measuring the object.

Put on

Sufficient

Lines should

and when sketch

sketched very lightly at first

all

dimension

is

approved

lines before

dimensions must be placed on

sketch to enable the draftsman to

make

a working drawing for

the pattern maker without having recourse to the object, after Sketch must be signed by the the drawing is commenced. Instructor. Callipers may be had at the office.

PLATE Problem

Make working drawing from the drop or post case may be, from the sketch made in Plate 8. = i foot. See Fig. 156, pencil drawing scale 6"

i.

hanger, as the

Make

9.

finished

page Z2Q, and Fig. 159, page 224, for similar hangers.

PLATE Problem steam

pump

i.

Make

10.

freehand sketch for water cylinder of

without the

adjacent

parts.

Make

longitudinal

section through the center of cylinder, plan of top, half cross-

DRAWING AND DESIGNING.

412

and half end view combined,

section,

also cross-section

through

supply and delivery ports. Scale about half size. Large circles may be drawn with compass. Follow directions given for Plate

8.

Problem

Make sketch of

2.

upper valve seat of water cylinder.

Show top and bottom views and turned Put on dimensions, notes,

finish

section through center.

marks, and

title

on

all

freehand

sketches unless otherwise directed.

Problem

Make

3.

freehand sketch of valve chest cover for

water cylinder, showing top and bottom views and turned section

through center.

Problem

Make

4.

freehand sketches of the following remain-

ing details of the water cylinder of steam

i,

pump:

1.

Piston and rod.

6.

Valve

2.

Stuffing-box.

7.

Valve disk.

3.

Gland.

8.

Valve spring.

4.

Ring.

9.

Valve cover.

5.

Air chamber.

2, 3,

sheet for 6,

4,

and

5

7, 8, 9,

plete as before.

10.

may be and

seat.

Valve spindle.

sketched on one sheet, using another

Make

10.

all

necessary views and com-

See sample sketch, Fig. 313, page 413.

PLATE n. Problem

Steam

i.

Make

Pump from

dimensions, notes, pencil drawing

assembly drawing for water cylinder for

sketches in Plate 10. title,

and

and trace on

bill

cloth.

Put on the principal

of material.

Scale 8" =

Make

i foot.

finished

ELEMENTARY MACHINE DRAWING.

413

DRAWING AND DESIGNING.

414

PLATE Problem

i.

Make

safety valve in detail 1.

freehand

12.

sketches

of

either

globe

or

on one sheet as follows:

Globe valve body, longitudinal section, half cross-section

and half end view combined. 2.

Valve stuffing box and bonnet, half elevation and half

section combined,

Problem

and plan.

2.

3.

Valve spindle, one view.

4.

Valve spindle nut, half elevation, half section and plan

.5. Hand

wheel, half elevation, half section, and plan.

6.

Valve, half elevation, half section, and plan.

7.

Valve nut, half elevation, half section, and plan.

8.

Stuffing

Problem 1.

box cap, half

elevation, half section,

and plan.

i.

Safety valve casing, half elevation, half section combined,

and plan. combined, and plan

2.

Valve

3.

Ring, half elevation, half section combined, and plan.

Problem

seat, half elevation, half section

2.

4.

Valve spring, elevation and plan.

5.

Valve spindle, one view.

6.

Adjusting screw, two views.

7.

Valve disk, two views.

8.

Spring washer, two views.

9.

Adjustable screw bushing, two views.

10.

Lock

nut,

two views.

ELEMENTARY MACHINE DRAWING.

PLATE Problem

i.

Make

detail

415

13.

assembly working drawing of either

the globe or safety valve from sketches

made

in Plate 12.

FIG. 314.

This drawing must be notes, to suit.

title,

and

bill of

fully

material.

dimensioned and contain Finish in pencil only.

all

Scale

DRAWING AND DESIGNING.

416

PLATE Problem

shown

i.

Make

in Fig. 314,

14.

iso metrical

drawing of layout of piping

page 415.

FIG. 315.

Samples of couplings and piping room.

will

be found

in the drafting

See Fig. 315 for sketch of J" globe valve.

Diameter

ELEMENTARY MACHINE DRAWING and thickness from Table Fig.

of pipes, length of screw, etc., can be obtained

page

7,

417

57.

316, page 416, shows the isometric layout of the center

lines of the piping.

space for

title

fully using

and

Arrange on sheet bill

of material.

to best advantage, allowing

Letter

all

notes very care-

Make

lower case letters and Gothic caps.

caps one

FIG. 316.

third

higher than small

pencil and

letters.

he

i

foot.

Finish in

trace.

PLATE If

Scale 4" =

15.

any student has time and desires

may make

to

increase his mark,

as an extra plate an assembly detail

ing of a chain oiling bearing similar to that

page 226, except that

it

shall

be designed

working draw-

shown for a

in Fig. 161,

ijf" shaft to

4 i8 suit either the

DRAWING AND DESIGNING. drop or post hanger of Plate

9.

Scale

= full

size.

Finish in pencil and trace on cloth, or a design for a donkey

pump, similar to that shown in Fig. 317, according and data to be given by the Instructor.

to directions

PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS AND METHODS IN MAKING PRACTICAL WORKING DRAWINGS.

SUMMARY REPORT OF AN INVESTIGATION MADE BY THE WRITER WITH THE AUTHORITY OF THE ARMOUR INSTITUTE OF TECHNOLOGY, CHICAGO, ILL.*, INTO THE PRESENT PRACTHE LEADING DRAFTSMEN IN THE UNITED STATES, THE USE OF STANDARD CONVENTIONS AND METHODS

TICE OF IN

WHEN MAKING COMMERCIAL WORKING DRAWINGS.

A

circular letter

accompanied by a

list

of thirty-five questions

was submitted to two hundred leading firms in the United States, embracing nearly all kinds of engineering practice. The returns have been exceedingly gratifying, and especially has been the spirit with which the " Questions" have been so received and answered.

Many

requests have been received from chief draftsmen for

a copy of the returns.

The

questions submitted and the answers received are given

somewhat

in detail below.

419

DRAWING AND DESIGNING.

420

Q.

i.

Do you

place complete information for the shop on the

pencil drawing, such as all dimensions, notes,

title,

bill

of

material, scale, etc. ?

Complete information

is

placed on drawing before tracing.

57

Complete information is placed on tracing only Principal dimensions and title only on pencil drawing

42

Draw

10

2

directly on bond paper Did not answer this question

10

Sometimes

7

Reasons given for making the pencil drawing complete:

To

made by Q.

2.

To save draftsman who makes

arrange notes. the

Do you

The

ime.

is

tracing

not usually

the pencil drawing.

ever ink the pencil drawing?

Never ink the pencil drawing

91

Generally ink the pencil drawing Sometimes ink the pencil drawing

7

8

Sometimes ink the pencil drawing and shellac Use bond paper

Make

Q.

lines of

Ink center

lines of pencil

Do

in

drawings

"

Vandyke

"

10 ..

2 i

red

prints for

Sometimes use paper drawings

Do

i

2

you trace on cloth and blue print?

Sometimes make

4.

shop use .

assembly drawing

Always trace on cloth and blue print Blue print from bond paper Blue print from bond paper occasionally

Q.

for

pencil drawings on dull side of tracing cloth

Ink center

3.

it

you use blue prints

Use blue

in

shop

102

10 .

.

for jigs

entirely in the

prints altogether in shop Sometimes use pencil drawings or sketch .

i

,

shop use

and

shop

i

fixtures.

i

?

105 21

PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS.

42!

Sometimes use sketches made with copying ink " Sometimes use prints from Vandyke "

Use white

Use blue

prints

prints

Use sketches

Q.

5.

When

i

mounted on cardboard

for rush

Ever use shade

i

work

i

uniform

use

wide

object

Never use shade

lines

100 21

on small details

Always use shade

lines?

lines ?

Use uniform, thick object lines. Sometimes use shade lines lines

i

mounted on cardboard and varnished

tracing do you

Use shade

i

5

lines

14

Experts in the use of shade lines

may do

so to

make drawings

clear

i

Shade rounded parts

Q.

6.

What kind

i

of a center line

Long dash, very narrow, and Long dash and two dots, Very

fine

continuous

Very

fine

dash

Long dash and dot Continuous fine red

dot, thus

in red, line,

7.

What

42 29 19

-

8

-

3

-

8

Long dash and three dots, Long dash and two dots, thus:

Q.

:

line,

long dashes,

line,

do you use ?

i -

i

kind of dimension line do you use ?

Continuous

broken only

fine line,

Fine long dash Fine long dash

-

line,

line

Fine continuous red

dot, -

52

-

13

4

line, -

line,

-

8

line,

Fine continuous green

dimension -

32

and

Fine continuous blue

for

i

DRAWING AND DESIGNING.

422

Same

character of line as center

Dotted

line,

Long dash and two Heavy broken lines, Q.

&.

What

,

line,

-

32

i

2

dots,

i

do you use ? Sloping ? Vertical ? All capitals of uniform height? or capitals

style of lettering

Free-hand?

and lower case ? Free-hand sloping

52

Free-hand

vertical

Free-hand

capitals, Gothic,

Free-hand

capitals,

. .

uniform height

and lower case

.

40

.

All caps, initials slightly higher

Lettering

left to

Mechanical

Not

5

option of draftsman

lettering, all

2

caps

.

particular, the neatest the

draftsman can make

3 free-

hand

4

Mechanical

lettering, all

Give great latitude

Roman, Large

Q.

9.

45 61

2

caps, sloping

in lettering,

only

insist

it

be bold and neat

i

caps and lower case, free hand

2

Aths, small ^\ds and Jth

2

letters

Are your

titles

and

bills of

material printed or lettered by

hand? Lettered by hand

Standard

titles

79

printed and

filled in

Bill of material table printed

and

by hand

lettered

by hand

Lettered by hand, contemplate having them printed B. of M. typewritten on separate sheet and blue printed. Titles partly printed

Use rubber stamp Standard

title,

cloth..

and

filled in

for standard

bill

of

12 i . .

by hand

title, fill

material

12

in

8

&

by hand

6

lithographed on tracing 8

PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS. Q.

10.

Do you

use a border line on drawings?

Always use border lines Never use border lines

Use border

No

lines

border lines

97 13

on foundation plans, on detail drawings

to

send out

i i

Intend to discontinue the use of border lines

i

used only on design drawings Only on drawings to be mounted on cardboard Only used for trimming blue print

i

Border

On

ii.

lines

i

2 i

assembly drawings only

Width Q.

423

of margins reported:

When

hatch-lining

i", J", f", i",

sections,

and J".

uniform

do you use

oi

symbolic hatch lines ? Standard symbolic

Uniform hatch Shade

lines

59

lines for all materials

section. part with

4H

pencil

44

and note name

of material

Symbolic hatch lines and add name of material Uniform hatch lines for metal only Uniform on details, symbolic on assembly drawings Pencil hatch on tracings

i 4

5

and note material other than

cast i

iron

Uniform hatch

No

lines,

sometimes solid shading

i

uniform system

i

Sections tinted with water colors representing the metals..

Q.

12. Is

4 3

the

pencil

stored or do you

drawing

make

"

preserved?

Vandyke"

Is

the

prints for storing

i

tracing

away?

Store tracings only

96

Pencil drawings preserved for a time

30

Pencil drawings preserved

13

White

prints

made and bound

Tracings kept in "

Vandyke

"

for reference

office for reference,

prints stored

blue prints stored

i

9 i

DRAWING AND DESIGNING.

424 Use

"

Vandyke

"

as

substitute for tracing

Arrangement drawings preserved, after job

is

detail

2

drawings destroyed

Pencil drawings used for gasket

completed.

i

paper Original pencil drawing inked

i

Assembly drawings and layouts preserved

4

Patent

i

Tried

Q.

and stored

13.

"

office

drawings preserved " Vandyke but found it unserviceable, tearing easily.

Do you

use

6H

i

grade of pencil for pencil drawings or

what?

6H

73

4H, mostly for

figures

and

letters

52

5H

16

Ranging from

Q.

14.

Do

2H

to

8H

53

you use plain orthographic projection for free-hand

sketches? sketches

Ever use perspective or isometrical drawing for

?

Plane orthographic 3d angle projection

99

Isometrical drawing for sketches

25

Perspective for sketches

i

.

Isometric for piping layouts and similar work

Perspective and isometric for catalogue work

2

Isometric sometimes

6

Never use free-hand sketches

6

One

"When we

says,

run into other than orthographic,

too timid and not sure of themselves.

work

Q.

8

is

15.

cylindrical,

What

9"Xi2"

workmen

get

sizes of sheets

mixed up on center

do you use

for

.w-v.;.,

men

In perspective drawings

are

when

lines.

drawings? 13

16

PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS. i8"X24". ...... .......... .......................... .........................................

There seems

to

be

little

make

20

..

19

uniformity in the sizes of shop drawings,

about 67 firms reporting different combinations. system but simply

425

A

few have no

the size of sheet to suit the object to be

drawn.

Q.

16.

Do you

use red ink on tracings?

Never use red ink on tracings ..........................

57

.............

2

Recently discarded the use of red ink .....

Use red ink

for pattern figures

Use red ink

for center

and dimension

Use red ink

for check

marks

Use red ink

for existing

.

......................... lines

i

...............

8

.......................

i

studies .................

i

Use red ink sometimes ........................... .....

2

.

Use red ink on occasions when in red

When

.

it is

desired to

show

old

work

and new work

Use carmine

Qs. 17 and

.

.

work on

for brick

27.

How

finished

all

in black (use carmine) ........... .................................

indicate finished

When

over?

planed, bored, drilled,

i i

surfaces on drawings? "file

finished,"

ground,

etc. ?

.................

65

Finished surfaces indicated as in Fig. 2 .................. Finished surfaces indicated as in Fig. 3 ..................

16

Finished surfaces indicated as in Fig. 4 ..................

2

Finished surfaces indicated as in Fig. 5 .................. Bound the surfaces with red lines ................. ......

2

Finished surfaces indicated as in Fig.

Bound

i

the surfaces with dotted lines ....................

Name the finish by note in full ........................ Do not specify machinery method ...................... .

(See drawing.)

8

2 2"

68 6

DRAWING AND DESIGNING.

426

Q.

18.

Do you

use horizontal or sloping lines for convention

in screw threads ?

Sloping

lines, see Fig.

Horizontal

6

94

lines, see Fig. 7

12

f/G. X

F/G.2.

j

r

_f

J

' .

Finish only third line from top

FIG.

FIG.

6.

Horizontal

FIG.

7.

lines, see Fig.

8

Both Neither, but as

8.

FIG,

9.

FIG. 10.

13 7

shown

in Fig. 9

Neither, but as shown in Fig. 10

i i

PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS. Q.

Ly.

When

a large surface

is

in

section

427

do you hatch-line

around the edges only ? 62

Hatch-line edges only .

Sometimes

3

section all over

Hatch

Do

-

54

shade the whole surface with

not use hatch lines;

4H 3

pencil line Usually show a broken surface

i

F/G.//. Q.

20.

Do you

lines

section

keyways

Section keyways as

shown

in Fig.

Show key way by invisible lines, Keyways in hubs left blank Q.

21.

hubs or show by

invisible

11

see Fig. 12

73

40 i

In dimensioning do you prefer to place the dimension

upon the

piece or outside of it?

Outside whenever possible

Upon

in

?

the piece

92 13

DRAWING AND DESIGNING.

428

Both, according to size and shape of part

No

i

Commenting on placing dimensions less confusion to workman."

outside

Q.

one says,

of piece

Another says:

"It entails

make

19

rule

"So

22.

Do

you use

feet

and inches over 24 inches?

Yes

69

Use

feet

Use

feet

and inches over 36" and inches over 24" on foundations and

Use

feet

and inches over 48"

4 outlines

.

.

21

For pulleys use inches up

to

48"

i

Inches up to 10 feet Start feet at

2

24" thus: 2-0"

2

Usually, but not always

2

Yes, except pitch diameters of gears, which are

all

given in

inches

2

Yes, except in boiler

Q.

Use

feet

and sheet iron work

and inches over

1

3

2"

6

Inches up to 100"

3

Inches up to 60"

i

23.

How

or thus

do you indicate

24.

feet

and inches?

Thus

2

ft.

4",

2-V ?

2-4" 97, 2 and 2-4"

Q.

2

6

All inches

,

as to

detail stand out."

Do you

4" i,

5, 2

FT.

2FT. 4 IN.

4"

2,

i, 2'

2ft.

4"

4"

8,

Both

13.

24^

2ft.

4"

i.

dimension the same part on more than one view?

One view : More than one view

;

:

as check

94 46

PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS. Q.

When

25.

several parts of a

429

drawing are identical would the

dimensioning of one part suffice for

or would you repeat

all,

the dimension on each part?

One part only Would repeat or .

" "

.

82

,

indicate by note " Left to judgment of draftsman

When

it is

Do you

26.

or DIA.

RAD DIA

Do Q.

.

.

..

write

'Would never

R

room

leave

RAD.

for radius or

for doubt.'"

?

D. for diameter

?

35

Rad

41

Dia

DIAM

....

.

.

.

.

i

.47

R

.... 32

D. ... 15 48 Diam. 3

rad.

d

.

.

. .

i

r

.

3

dia

.

diam

3 .

..

Do you always When you do how are

Only give number

i

number

they indicated

of threads

All others always indicate

A

give

of

threads

per inch?

?

when not standard

number

few of the different

4

5

not use R. or RAD., dimension only

28.

ways.

i

evident that several parts are identical the dimensioning

of one part would suffice,

Q.

39

67

of threads in a great variety of

styles of noting the threads are given

below:

J" .

10 Thr. 5THDS. PER i". Sthds. 4 threads per inch. Mach. Screw 10-24, il" XII, 16 P. RH. Vth. U. S. S. XVIII, r "-8U. S. S. i" TAP, 8 PITCH, 3 TH'D R. H. SQ. DOUBLE, 5"-i8

THDS.

J"

Q.

29.

R. H.

OWN

ST'D io thds. per inch.

For pipe tap thus,

P.T., etc., etc.

How

do you

"Mark"

a piece to indicate on the

bill of

material ?

Number

it

on drawing and put a

circle

around

it

34

DRAWING AND DESIGNING.

430

By name or letter By pattern number By symbol and number Castings,

Q.

I, II,

When

30.

35 2

14

III, Forgings, i, 2, 3.

a working drawing

is

For convenience

Check against Not necessary

of drafting

dimensioned why

fully

should the scale be placed on the drawing

?

room

25

errors

11

18

Scale not placed on shop drawings

For convenience

To

in calculations

18

and planimeter work

"

as to warrant leaving off the scale

"

i

give an idea of over-all dimensions when these are not " We never saw a drawing so fully dimensioned given. 2

If a drawing is to scale the scale should be on the drawing, whether needed or not."

it is

"

every one interested a better conception of the proportions of the piece, and there are frequently portions of a design which do It gives

shop to work to, and which it is from an engineering point of view." "To get approximate dimensions not given on drawing." "Impractical to dimension all measurements for all classes of

not require a dimension for the interesting to scale

work." "Scale

will

tell

at

a

glance,

dimensions

would

have

to

be

scaled."

"To

obtain an idea of relative size of parts without scaling the

drawings." "To sketch on clearance." erecting to

" "

measure

"To

In case a dimension has been

This

insist

on

is

it."

a question of opinion

"We

proportion

changes."

"When

over-all sizes." left off, ;

some

the scale will help out."

will

always give the scale."

not have the scale, others

PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS.

an immense help and time saver in the drawing room." Generally no reason. In our work we combine standard apparatus

"It "

is

'

by

431

and

'

fudge

tracing,

it is

know

convenient to

scale so all parts will

surely be to same scale."

"In discussing

know

venient to

alterations,

room.

in drafting

on with a reference

To

etc.,

it

is

con-

the scale instantly."

"For convenience scale "

additions, clearances,

We

often put an arbitrary

letter indicating scale to

draftsman."

give toolmaker an idea of the size of the finished piece."

"As an

aid to the eye in reading."

Above are some

of the reasons given for placing the scale

Below are given a few

drawing.

of the reasons

on the

why some do not

place the scale on the drawing. "

Scale should never be used in shop," says one.

Sometimes drawing is made out of scale." on account of workmen getting into the habit of advisable,

"Not

necessary.

"Not

to scale instead of to the figures."

working " " "

Know

of

Believe

no good reason

it

best to leave scale off."

Should not.

"Know

at all."

Drawing should never be scaled."

no good reason why it should be." "Should not be given on drawing." "

Do

Q. 31.

of

not object

Do you

if left off,

use the glazed or dull side of tracing cloth?

Glazed side. 32

Dull side ... 66

"Dull

side,

not needed."

because

it lies

flat

Both

4

better in drawers."

"

Dull side, so that changes which may be necessary while work under construction, can be made easily in pencil and later in ink." "

Dull side so tracings

may

is

be checked in pencil."

"It prevents curling." "

Both, although the glazed side

drawer."

when

traced on

lies

better in the

DRAWING AND DESIGNING.

432

"We use cloth glazed on both sides, work on convex side, so that shrinkage of ink will eliminate camber." " to

Dull, except for U. S. Government,

who

requires the glazed side

be used."

How

Q. 32.

Pattern

do you place pattern numbers on castings?

number with symbol or letter e.g., PATT.-D-478-C

is

placed on or near

the piece,

36

This question was not happily stated; most answers gave "raised letters cast

on," while the question like

How

Q. 33.

all

the others refers to the

of the drawing.

marking

do you note changes on a drawing?

On tracing with date New tracing and new number Put a it

17

and

figure

write

new

figure beside

8

with date

Make new Red

around old

circle

32

5

tracing

ink with date

8

.'

" Use rubberstamp Revised" with on record print

date,

and indicate changes 28

Use change card system

i

Change -made

Special forms for purpose.

New

date.

with draftsman's

Do you

Q. 34.

made

prints

initials

place

No

right

hand

.

..'

R

to

L

In place at

title

8

read

from bottom and

from bottom, or how ?

103

fixed rule

From

book with

and date

dimensions to

right hand, or all to read

Bottom and

to replace.

in a

From bottom

only

2 2

and bottom

to top

i

PRESENT PRACTICE IN DRAFTING ROOM CONVENTIONS. Q. 35.

Do you

material

always

table

contain

to

the

bill

of

?

Yes

49

Usually Bills

make a

433

.

No

Not always.

25 i

on general drawings only.

Use separate

On

details

bill

number

.

5

32 is

marked on

piece.

"No, but system."

it

is

advisable to

do so."

"Have abandoned

that

INDEX.

Aluminum,

Angle, Lead, 307

Area

of a bearing, 200

B Babbitt metal, 33 Ball bearings, 230 Base plates, Adjustable, 230 Bearing, Adjusting wedges for, 355 Bearing, Area of a, 206 Bearing, Cap of, 354 Bearing, Chain lubricating, 225 Bearing, Crank-shaft or main, 351 Bearing, Four-part, 353 Bearing, Gibs for, 355 Bearing, Length of, 235 Bearing, Load on ball, 360 Bearing, Pedestal or pillow-block, 230 Bearing, Pivot or step, 347 Bearing, Post, 214 Bearing, Solid journal, 207 Bearing, Self-adjusting, 217 Bearing, Three-part, 351 Bearing, Thrust, 361 Bearings, Blocks for, 356 Bearings, Diameter of studs for, 355 Bearings, Divided, 210 Belt gearing, 238

Belting, Rules for, 240 Belts,

Belts,

Length of, 253 Transmission of power by,

213

Bolt,

Anchor, 82

Bolt,

Hook,

%

76 Bolt, Lewis, 80 Bolt of uniform strength, 91 Bolt, Rag, 78 Bolt, Square-headed, 67

33

240,

Bolt, Stud, 68 Bolt, Tap, 75

Bolt, Tapered, 77

T-headed, 74 Brass, 32 Bronze or gun-metal, 32 Bushes, steps or brasses, 227

Bolt,

C Calking, 126 Case-hardening, 34 Castings, Malleable, 32 Castings, Shrinkage of, 44 Cast iron, 30 Cast iron, Specific gravity of, 40 Cast-iron water-pipe, Thickness 43

Cast steel, 32 Cementation process, 35 Chilled castings, 31 Clearance, Cylinder, 308 Clearance, Inside, 308 Clearance, Piston, 308

Compression, 308 Cock, Blow-off, 295 Cocks, 295 Connecting-rod, Thrust

of, 345

435

of,

INDEX. Cylinder flange fastenings, 69

Connecting-rods, 339 Connecting-rods, Buckeye

Engine Cylinder, Diameter of steam, 328 Co., 341 Cylinder, Length of steam, 329 Connecting-rods, Diameter of, 346 Cylinder, Steam, 328 Iron Cylinder, Thickness of steam, 328 Connecting-rods, Erie City

Works,

341

Connecting-rods, Marine, 344 Penn. Railroad Connecting-rods,

Cylinder head, 329 Cylinder steam-port, 329

D

Co.'s, 343

Connecting-rods, Proportions of locomotive, 347 Constructions, 26 Conventions, Standard, 20

Copper, 32 Cotter and gib, 120 Cotter locking arrangement, 122 Cotter,

Taper

of, 117

Eccentrics, 379 Eccentrics, Proportions of, 382 Eccentric, Throw of, 380 Elasticity, 37

Cotters, 116

Couplings, Couplings, Couplings, Couplings,

Design, Elementary machine, 29 Design of spur gear, 271

Box

Elasticit) Modulus of, 37 Elastic limit, 37 r

or muff, 165

,

Cast-iron pipe, 190 Converse pipe, 197

Flanged shaft, 178 Couplings for brass and copper pipes,

Engine details, 305 Engine-frame or bed-plate, 326 Expansion, 308

203

Couplings, Couplings, Couplings, Couplings, Couplings, Couplings, Couplings, Couplings, Couplings, Couplings, Couplings, Couplings, Couplings,

Frictional, 174 Hill plate, 171 Jaw clutch, 181

Pipe, 190

Propeller shaft, 185 Rigid, 164 Screwed flange pipe, 198 Screwed socket, 200 Sellers clamp, 171 Shaft, 164 Spiral jaw, 181

Spigot and socket

193

Couplings, Couplings, Couplings, Couplings,

Figuring, 19 Factor of safety, The, 38 Frame, Drop-hanger, 218

Loose flange, 195

Split muff, 167

Stuart's clamp, 176 Universal joint, 185

Wrought-iron and

pipe, 196

Cross-heads, 376 Cross-head blocks, 368 Cross-heads and guides, 368 Cross-sections, 26

Gearing, Belt, 238 Gearing, Toothed, 262 Gears, Bevel, 270 Gears, Involute toothed, 263 Gears, Spur-wheel and pinion, 268 pipe, Gears, Walker system of, 267 Gears, Worm, 271 Gear-wheels, Arms of, 274 Gear-wheels, Hubs of, 276 Gear-wheels, Rims of, 275 steel- Gear-wheels, Shrouding of, 276 Guide, Four-bar, 372 Guide, Two-bar, 374 Guide-bars, 370 Guide-bars, Length of, 372 Guides, Strength of, 372

INDEX.

Instructions, Introductory,

Instruments,

Nut, Jam, 92 Nut locking devices, 92

I

7

J Joint,

437

Forms and proportions

of cot-

Nut-lock, Circular, 99 Nut-lock, Spring washer, 94 Nut-lock, Wile's, 95 Nuts locked with set-screws, 96

ter, 118

Joint,

O

Knuckle, 106 Oil-cups, 299

Joint, Lap, -143 Joint,

Locomotive steam-pipe

ball,

200

Overtravel, 308

Joints, Riveted, 125

Journals, 206

K Key-heads, 114 Key, Flat, no Key, Round, 112 Key, Saddle, 109 Key, Sliding feather, 113 Key, Sunk, no Key, Woodruff, 113 Keys, 109 Keys, Fixed, 112 Keys, Strength of, 114

Lead, 307

Lead angle, 307 Lettering, 194 Load, 365

Locomotive Locomotive Locomotive Locomotive

dome

connection, 156

fire-box ring, 154

plain slide-valve, 305

tube-setting, 155

M Malleable castings 32 s

Materials, 30 Materials, Strength of, 36 Metallic packing, 366 Metallic packing, United States, 366 Muntz metal, 32

N Nut convention, 63 Nut, Hexagon, 60

Pedestal, Self-lubricating, 232 Pin-joint, Knuckle, 106

Pins and pin-joints, 104 Pins, Split, 104 Pins. Taper, 105

Pipes, 189 Pipes, Thickness of, 189 Piston, Ball Engine Company's, 333 Piston, Buckeye Engine Company's

338 Piston clearance, 308 Piston, Locomotive, 334 Piston, Macintosh & Seymour's, 336 Piston, Water, 340 Pistons, 332 Pistons, Steam, 332, 335 Point of cut-off, 308

Pressure on rubbing surfaces, 369 Projection of India-rubber valveguard, 282 Proportions of India-rubber valveguard, 283 Pulley, All wrought-steel, 250 Pulley, Cone, 251

Pulley, Rope, 255 Pulley, Wood split, 248 Pulleys, Proportions of, 244 Pulleys, Proportions of cone, 255

R Resistance, 37

Riveted Riveted Riveted Riveted

butt-joint,

Double, 144

butt-joint, Triple, 148 joint, Calculation of, 136

lap-joints, Double, 139

INDEX.

438 Rivet-head, Proportions of, 130 Rivet-heads, Form of, 128 Riveting, Chain, 139 Rivets and riveted joints, 125

Rivet-shank, Length

of,

130

Rivets, Pitch of, 136

Screw, Cap, 85 Screws, Collar, 85 Screws, Holding power of, 88 Screw-thread, Buttress, 55 Screw-thread, Knuckle, 55 Screw-thread, Seller's or U. S. stand ard, 51

Screw-thread, Square, 55 Screw-thread, Standard pipe, 56 Screw-thread, Whitworth, 53 Screw-threads, Conventions for, 59 Shade lines and shading, 15 Shaft, To find diameter of steel, 159 Shaft-couplings, 164 Shafting, Deflection Shafting, Line, 157 Shafts, Hollow, 163 Steel,

etc., 46

Table of the weight of various substances, 46

Table of the weight of timber, 46 Table of the circumferences and areas of circles, 47 Table of screw threads, 70 Table of saddle and flat keys, no Table of rectangular sunk keys, in Table of single-riveted joints, 135 Table of single-riveted joints, 136 Table of double-riveted joints, 141 Table of double-riveted lap-joints, 144 Table of double-riveted butt-joints, 147

Table

162

Bessemer, 34 Siemens-Martins, 34

Steps, 227

Stuffing-boxes, 363 Strain and stress, 36 Strength of cast iron, 38

Strength of steel, 39 Strength of wrought iron, 39 Strength, Proof, 38 Strength, Ultimate, 37

Table of ultimate and elastic strength, 40

Table of tenacities of metals, 40 Table of weights and measures, 41 Table of wrought iron welded tubes,

of

triple-riveted

butt-joints,

149 Table of Sellers clamp couplings, 174 Table of flanged shaft couplings, 180 Table of jaw clutch couplings, 183

Table of,

Sole-plates, 229 Steel,

Table of the melting-point of metals,

of

standard

cast-iron

pipe

flanges, 192 Table of Pope pipe couplings, 196 Table of steam-pipe connections, 206 Table for brass, copper, and wrought-

iron pipes, 204

Table of sections, 205 Table of thickness of belting, 243,244 Table of proportions of cone pulleys, 255

Table of proportion of rope pulleys, 258, 261

Table, Odontagraph, 265, 266 Table of India-rubber disk valves, 290 Table of locomotive-piston proportions, 334 Table of thickness of pipes, 189 Table of thickness of India-rubber valve disks, 283 Table of thickness of steam-cylinders, 328

44

Table of different colors of iron, 45 Table of decimal equivalents of one Valve, Allen-Richardson balance, 309 inch, 45

Valve, American balance,

3iv,

INDEX. Valve, Valve, Valve, Valve,

Angle of advance of

slide, 307

Ball, 288

Flat India-rubber disk, 290 foot and strainer, 278

Globe, 292 India-rubber, 280 Inside clearance of

Lead of

Valve, Point of compression of slide, 305

Boiler check, 295 Cocks and oil cup, 278

Valve diagram, The Bilgram, 313 Valve diagram, The Zeuner, 320 Valve, Valve, Valve, Valve, Valve, Valve,

439

slide, 308

slide, 307

Valve, Overtravel of slide, 308 Valve, Lift or wing, 285 Valve. Plain slide, 305 Valve, Point of admission of slide, 305 Valve, Point of cut off of slide, 308 Valve, Point of exhaust of slide, 305

Valve, spindle, 285 Valve, stop, 292 Valve, Travel of, 307

W Wall box frames, 211 Wall brackets, 216 Wall or post hanger, 223 Weights of cast-iron water-pipes, 42

Wooden teeth or cogs, 263 Woods used in construction, Working drawings,

35

17

Wrist-pin, 370 Wrought metals, 33

Wrought

iron, Specific gravity of s 40.

Wrought-iron welded tubes, 44

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at

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25

50 7 50 i 50

ARCHITECTURE. Baldwin's Steam Heating for Buildings I2mo, Berg's Buildings and Structures of American Railroads 4to, Birkmire's Architectural Iron and Steel ,8vo, Compound Riveted Girders as Applied in Buildings 8vo, Planning and Construction of American Theatres 8vo, Planning and Construction of High Office Buildings 8vo, Skeleton Construction in Buildings. 8vo, Briggs's Modern American School Buildings 8vo, Byrne's Inspection of Material and Wormanship Employed in Construction. Carpenter's Heating and Ventilating of Buildings * Corthell's Allowable Pressure on Deep Foundations

1

253 5 oo

3 50 2 oo 3 oo 3 50 3 oo

4 oo

i6mo,

3 oo

8vo,

4 oo

12010,

i

25

8vo

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50 50 50 50 oo 3 oo i 50 3 50 3 oo 6 oo

8vo, Sheep, 6 50 Law of Contracts 8vo, 3 oo Law of Operations Preliminary to Construction in Engineering and Architecture 8vo, 5 oo -

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Sheep, 5 50 Wilson's Air Conditioning. I2mo, i 5-' Worcester and Atkinson's Small Hospitals, Establishment and Maintenance, for Suggestions Hospital Architecture, with Plans for a Small Hospital.

i2mo,

ARMY AND

i

25

NAVY.

Bernadou's Smokeless Powder, Nitro-cellulose, and the Theory of the Cellulose Molecule i2mo, 2 50 Chase's Art of Pattern Making i2mo, 2 50 Screw Propellers and Marine Propulsion 8vo, 3 oo Cloke's Enlisted Specialist's Examiner. (In Press.) Gunner's Examiner T 50 8vo, Craig's Azimuth 4to , 3 50 Crehore and Squier's Polarizing Photo-chronograph 8vo, 3 oo * Davis's Elements of Law 8vo, 2 50 * Treatise on the Military Law of United States 8vo, 7 oo Sheep,

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50 5 oo

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Metcalf's Cost of Manufactures

And

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Vols.

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and

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8vo, the Administration of Workshops. .8vo,

Nixon's Adjutants' Manual Peabody's Naval Architecture.

4 oo 2 oo i oo

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* Phelps's Practical Marine Surveying 8vo, Putnam's Nautical Charts. (In Press.) i8mo, mor. i 50 Sharpe's Art of Subsisting Armies in War * Tupes and Poole's Manual of Bayonet Exercises and Musketry Fencing. 24mo, leather, 50 * Weaver's Military Explosives 8vo, 3 oo Woodhull's Notes on Military Hygiene i6rno, i 50

ASSAYING. Lead Refining by Electrolysis 8vo, Fletcher's Practical Instructions in Quantitative Assaying with the Blowpipe.

Betts's

i6mo, Furman's Manual of Practical Assaying Lodge's Notes on Assaying and Metallurgical Laboratory Experiments. Low's Technical Methods of Ore Analysis .

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mor.

50

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lamo, I2mo, i2mo, 8vo, 8vo, 8vo, 8vo,

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Cyanide Processes.

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3 oo 3 oo

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4 oo

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I

oo oo

2 50

2 oo

3 oo 4 oo 3 oo i i

50 50

ASTRONOMY. Comstock's Field Astronomy for Engineers Craig's Azimuth -Crandall's Text-book

on Geodesy and Least Squares

on Practical Astronomy Gore's Elements of Geodesy Hayford's Text-book of Geodetic Astronomy

Doolittle's Treatise

Merriman's Elements of Precise Surveying and Geodesy * Michie and Harlow's Practical Astronomy Rust's Ex-meridian Altitude, Azimuth and Star-Finding Tables. * White's Elementsiof Theoretical and Descriptive Astronomy 3

8vo, 4 to,

2 50

3 50 .8vo, 3 oo 8vo, 4 oo 8vo, 2 50 8vo, 3 oo 8vo,

2 50

8vo,

3 oo

(In Press.)

i2mo,

2 oo

CHEMISTRY. * Abderhalden's Physiological Chemistry in Thirty Lectures.

(Hall and Defren)

8vo, * Abegg's

of Electrolytic Dissociation, (von Alexeyeff'c General Principles of Organic Syntheses'. Allen's Tables for iron Analysis

Theory

Ende) (Matthews)

5 oo

lamo,

i

25

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3 oo

8vo, Arnold's Compendium of Chemistry. (Mandel) Large i2mo, Association of State and National Food and Dairy Departments, Hartford,

3 oo 3 50

Meeting, 1906 8vo, Jcinestown Meeting, 1907 8vo, Austen's Notes for Chemical Students i2mo, Baskerville's Chemical Elements. (In Preparation.) Bernadou's Smokeless Powder. Nitro-cellulose, and Theory of the Cellulose Molecule lamo, * Blanchard's Synthetic Inorganic Chemistry i2mo, * Browning's Introduction to the Rarer Elements. 8vo, Brush and Penfield's Manual of Determinative Mineralogy 8vo, * Claassen's Beet-sugar Manufacture. (Hall and Rolfe) 8vo,

3 oo

Classen's Quantitative Chemical Analysis by Electrolysis. Cohn's Indicators and Test-papers

Tests and Reagents * Danneel's Electrochemistry.

(Merriam)

(Boltwood).

.8vo,

50

2

50 oo

i i

4

3

i2mo, 8vo,

3

I2mo,

(Burgess) 8vo, Eakle's Mineral Tables for the Determination of Minerals by their Physical Properties 8vo, Eissler's Modern High Explosives 8vo, Effront's Enzymes and their Applications. (Prescott) 8vo, Erdmann's Introduction to Chemical Preparations. (Dunlap) i2mo, * Fischer's Physiology of Alimentation Large i2mo, in Practical Instructions Fletcher's Quantitative Assaying with the Blowpipe.

I2mo, mor. i2mo,

Works Analyses

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3 2

.

Duhem's Thermodynamics and Chemistry.

Fowler's Sewage

3 oo

50 oo oo oo oo oo

i 25 4 oo

125 4 oo 3 oo i 25 2 oo

50 oo 5 oo 3 oo 8vo, 12 50 i

2

Manual of Qualitative Chemical Analysis. (Wells) 8vo, Manual of Qualitative Chemical Analysis. Part I. Descriptive. (Wells) 8vo,

Fresenius's

Quantitative Chemical Analysis. (Cohn) 2 vols When Sold Separately, Vol. I, $6. Vol. II, $8. Fuertes's Water and Public Health

i2mo, i 50 Furman's Manual of Practical Assaying 8vo, 3 oo * Getman's Exercises in Physical Chemistry i2mo, 2 oo Gill's Gas and Fuel Analysis for Engineers I2mo, i 25 * Gooch and Browning's Outlines of Qualitative Chemical Analysis. Large i2mo, i 25 Grotenfelt's Principles of Modern Dairy Practice. (Woll) i2mo, 2 oo Groth's Introduction to Chemical Crystallography (Marshall) i2mo, i 25 Hammarsten's Text-book of Physiological Chemistry. (Mandel) 8vo, 4 oo Hanausek's Microscopy of Technical Products. Winton) 5 oo 8vo, * Haskins and Macleod's Organic Chemistry i2mo, 2 oo Helm's Principles of Mathematical Chemistry. (Morgan) i2mo, i 50 Bering's Ready Reference Tables (Conversion Factors) * Herrick's Denatured or Industrial Alcohol Hinds's Inorganic Chemistry * Manual for Students

i6mo, mor. 8vo,

8vo,

Laboratory i2mo, * Holleman's Laboratory Manual of Organic Chemistry for Beginners. (Walker) I2m o, Text-book of Inorganic Chemistry. (Cooper) 8vo, Text-book of Organic Chemistry. (Walker and Mott) 8vo, Holley and Ladd's Analysis of Mixed Paints, Color Pigments, and Varnishes. Large 12 mo,

4

2 50 4 oo 3 oo i oo

i

2

oo 50

2 50 2

50

Hopkins's Oil-chemists' Handbook Rock Minerals

8vo, 8vo,

Iddings's

Jackson's Directions for Laboratory Work in Physiological Chemistry. .8vo, Johannsen's Determination of Rock -forming Minerals in Thin Sections. .8vo, (In Preparation.) Johnson's Chemical Analysis of Special Steels. 8vo, Keep's Cast Iron .

3 oo 5 oo i

25

4 oo

2 50 Ladd's Manual of Quantitative Chemical Analysis i2mo, i oo Landauer's Spectrum Analysis. (Tingle) 8vo, 3 oo * Langworthy and Austen's Occurrence of Aluminium in Vegetable Prod.8vo, - oo ucts, Animal Products, and Natural Waters Lassar-Cohn's Application of Some General Reactions to Investigations in i2mo, i oo (Tingle) Organic Chemistry. Leach's Inspection and Analysis of Food with Special Reference to State

Control

8vo,

Lob's Electrochemistry of Organic Compounds. (Lorenz) Lodge's Notes on Assaying and Metallurgical Laboratory Experiments

8vo, 8vo, 8vo,

Low's Technical Method of Ore Analysis Lunge's Techno-chemical Analysis. (Cohn).." *

McKay and Larsen's Principles and Practice Maire's Modem Pigments and their Vehicles

I2mo, of Butter- making

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i2mo, Mandel's Handbook for Bio-chemical Laboratory I2mo, * Martin's Laboratory Guide to Qualitative Analysis with the Blowpipe I2mo, Mason's Examination of Water. (Chemical and Bacteriological.). ..i2mo, Water-supply. (Considered Principally from a Sanitary Stan dpi .

7 50 3 oo 3 oo 3 oo i oo i 50 2 oo I

50 60

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25

.

.

8vo,

Matthews's Textile Fibres. 2d Edition, Rewritten * Meyer's Determination of Radicles in Carbon Compounds.

8vo,

(Tingle). ,i2mo, Cyanide Process i2mo, of Assaying i2mo, Minet's Production of Aluminum and its Industrial Use. (Waldo) i2mo, Mixter's Elementary Text-book of Chemistry I2mo, Morgan's Elements of Physical Chemistry i2mo, Outline of the Theory of Solutions and its Results i2mo, * for Electrical Chemistry Engineers Physical i2mo, Morse's Calculations used in Cane-sugar Factories i6mo, mor. * Muir's History of Chemical Theories and Laws 8vo, Mulliken's General Method for the Identification of Pure Organic Compounds. Vol. I Large 8vo, O'Driscoll's Notes on the Treatment of Gold Ores 8vo, Ostwald's Conversations on Chemistry. Part One. (Ramsey) i2mo, Part Two. (Turnbull) i2mo, * Palmer's Practical Test Book of Chemistry i2mo, * Pauli's Physical Chemistry in the Service of Medicine. (Fischer^ ..... i2mo, * Penfield's Notes on Determinative Mineralogy and Record of Mineral Tests. Miller's

Manual

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4 oo 4 oo i 25 i oo i oo 2 50 i 50 3 oo i

50 50 oo 4 i

5 oo 2 oo i 50 2 oo i i

8vo, paper, Tables of Minerals, Including the Use of Minerals and Statistics of Domestic Production 8vo, i Pictet's Alkaloids and their Chemical Constitution. (Biddle) 8vo, 5 Poole's Calorific Power of Fuels 8vo, 3 Prescott and Winslow's Elements of Water Bacteriology, with Special Reference to Sanitary Water Analysis i2mo, i * Reisig's Guide to Piece-dyeing 8vo, 25 Richards and Woodman's Air, Water, and Food from a Sanitary Standpoint..8vo, 2 Ricketts and Miller's Notes on Assaying 8vo, 3 Rideal's Disinfection and the Preservation of Food 8vo, 4 Sewage and the Bacterial Purification of Sewage 8vo, 4 Riggs's Elementary Manual for the Chemical Laboratory 8vo, i .

Robine and Lenglen's Cyanide Industry. (Le Clerc) Ruddiman's Incompatibilities in Prescriptions

Whys

in

Pharmacy

8vo, 8vo,

I2mo, 5

oo

i

OQ 25

50

oo oo oo

50 oo oo oo oo oo 25.

4 oo 2 oo i

oo

Ruer's Elements of Metallography. (Mathewson) (In Preparation.) Sabin's Industrial and Artistic Technology of Paints and Varnish Salkowski's Physiological and Pathological Chemistry. (Orndorff) Schimpf's Essentials of Volumetric Analysis

*

8vo,

3 oo 2 50

12 mo,

125

8vo,

25 50 2 50 3 oo 3 oo

8vo,

Qualitative Chemical Analysis

Text-book of Volumetric Analysis Smith's Lecture Notes on Chemistry for Dental Students Spencer's Handbook for Cane Sugar Manufacturers Handbook for Chemists of Beet-sugar Houses Stockbridge's Rocks and Soils * Tillman's Descriptive General Chemistry * Elementary Lessons in Heat

i2mo, .Svo

Biology.

(In Press.) Vol. I

Ware's Beet-sugar Manufacture and Refining.

Vol.11

Washington's Manual

of the

Chemical

Analysis of

8vo,

i2mo, 8vo

i 50 3 oo

Small 8vo, SmallSvo,

4 oo

8vo,

8vo> 8vo> 8vo>

,

Rocks

8vo,

* Weaver's Military Explosives 8vo, Wells's Laboratory Guide in Qualitative Chemical Analysis 8vo, Short Course in Inorganic Qualitative Chemical Analys's for Engineering Students I2mo, Text-book of Chemical Arithmetic i2mo,

Drinking-water Whipple's Microscopy Wilson's Chlorination Process of Vegetable

Foods

,

oo

3 oo i

50

I2mo, i2mo, 8vo,

7 50

8vo,

Cyanide Processes

500 2

50 25 3 50 i 50 i 50

of

Winton's Microscopy

2

50 3 oo i 50 3 oo 4 oo 5 oo

8vo,

Treadwell's Qualitative Analysis. (Hall) (Hall) Quantitative Analysis. Turneaure and Russell's Public Water-supplies Van Deventer's Physical Chemistry for Beginners. (Boltwood) Venable's Methods and Devices for Bacterial Treatment of Sewage

Ward and Whipple's Freshwater

v

i6mo, mor, i6mo, mor.

r

*

.

i i

CIVIL ENGINEERING.

BRIDGES AND ROOFS. ING.

HYDRAULICS. MATERIALS OF ENGINEERRAILWAY ENGINEERING.

Baker's Engineers' Surveying Instruments i2mo, Bixby's Graphical Computing Table Paper igV v 24! inches. Breed and Hosmer's Principles and Practice of Surveying. 2 Volumes. Vol. I. Elementary Surveying 8vo, Vol. II. Higher Surveying 8vo, * Burr's Ancient and Modern Engineering and the Isthmian Canal .... 8vo,

Comstock's Field Astronomy for Engineers * Corthell's Allowable Pressures on Deep Foundations Crandall's Text-book on Geodesy and Least Squares Davis's Elevation and Stadia Tables

8vo,

i2mo, 8vo, 8vo,

Engineering for Land Drainage Farm Drainage *Fiebeger's Treatise on Civil Engineering Flemer's Phototopographic Methods and Instruments Folwell's Sewerage. (Designing and Maintenance.) Elliott's

I2mo, i2mo,

Practical

.

2? 3 oo 2

50

3 50 2 50 i 25 3 oo i oo

.8vo,

8vo,

3 50

8vo,

2

Goodhue's Municipal Improvements i2mo, Gore's Elements of Geodesy 8vo, * Hauch's and Rice's Tables of Quantities for Preliminary Estimates izmo, Text-book of Geodetic 8vo, Hayford's Astronomy i6mo, mor. Bering's Ready Reference Tables. (Conversion Factors) Howe's Retaining Walls for Earth izmo, 6 .

oo

50 op 5 oo 5 oo 3 oo

8vo, 8vo,

Freitag's Architectural Engineering French and Ives's Stereotomy

3

i r

50 50 50 i 25 3 oo 2 50 i 25 i

2

i6mo, Bds. i6mo, mor.

* Ives's Adjustments of the Engineer's Transit and Level Ives and Hilts's Problems in Surveying of Surveying (J. B.) Theory and Practice

Small 8vo,

Johnson's Methods 8vo, Johnson's (L. J.) Statics by Algebraic and Graphic (In Preparation.) Kinnicutt, Winslow and Pratt's Purification of Sewage. and 'Truscott Emory) Laplace's Philosophical Essay on Probabilities.

25 50 4 oo 2 oo i

OO SO 5 oo 2 50 2 oo 3 SO

2

I2I11O,

8v o

Mahan's Descriptive Geometry (Wood) ( 1873.) Treatise on Civil Engineering. Merriman's Elements of Precise Surveying and Geodesy Merriman and Brooks's Handbook for Surveyors

Rideal's

Sewage and

Riemer's Shaft-sinking under Difficult Conditions.

8vo,

8vo,

i6mo, mor. 8vo,

Nugent's Plane Surveying (In Press.) Ogden's Sewer Construction. Sewer Design Parsons's Disposal of Municipal Refuse Patton's Treatise on Civil Engineering Reed's Topographical Drawing and Sketching the Bacterial Purification of

2

8vo,

2

7

4to,

5

8vo,

4

8vo,

3

Sewage (Corning and Peele).

Tracy's Plane Surveying * Trautwine's Civil Engineer's Pocket-book Venable's Garbage Crematories in America Methods and Devices for Bacterial Treatment of Sewage Wait's Engineering and Architectural Jurisprudence of Contracts of Operations Preliminary to Construction in

tecture.

^mo, 8vo, half leather,

Siebert and Biggin's Modern Stone-cutting and Masonry (McMillan) Smith's Manual of Topographical Drawing. Soper's Air and Ventilation of Subways

Law Law

J

.

8vo,

i

8vo,

2

Large i2mo, i6mo, mor. i6mo, mor.

2 3

5 2

8vo, 8vo,

3 6 6

8vo, Sheep,

8vo Engineering and Archi8vo

3

5 oo 5 So

Sheep, 8vo,

Warren's Stereotomy Problems in Stone-cutting * Waterbury's Vest-Pocket Hand-book of Mathematics for Engineers. a|X 5! inches, mor. Webb's Problems in the Use and Adjustment of Engineering Instruments. i6mo, mor. Wilson's (H. N.) Topographic Surveying Wilson's (W. L.) Elements of Railroad Track and Construction.

oo oo 50 oo oo oo 50 50 50 oo oo oo oo oo 50 oo

2

50

i

oo

i

25

3 50

8vo.

(In Press.)

BRIDGES AND ROOFS, on the Construction of Iron Highway Bridges 8vo, Burr and Balk's Design and Construction of Metallic Bridges .... .8vo, Influence Lines for Bridge and Roof Computations 8vo, Du Bois's Mechanics of Engineering. Vol. II Srrall 410, Foster's Treatise on Wooden Trestle Bridges 4 to, Boiler's Practical Treatise

Fowler's Ordinary Foundations

g vo>

French and Ives's Stereotomy gVOf Greene's Arches in Wood, Iron, and Stone 8vo, Bridge Trusses g vo> Roof Trusses gvo, Grimm's Secondary Stresses in Bridge Trusses 8vo, Heller's Stresses in Structures and the Accompanying Deformations gvo, Howe's Design of Simple Roof- trusses in Wood and Steel 8vo, Symmetrical Masonry Arches g vo> Treatise on Arches g vo Johnson, Bryan, and Turneaure's Theory and Practice in the Designing of

Modern Framed Structures

2

oo

5 oo 3 oo 10 oo '

5 oo 3 go 2 go 2

2

50 5O

I

25

2 50

3 oo 2

oo

2 so .

oo

Small 410, 10 oo

7

Merriman and Jacoby's Text-book on Roofs and Bridges Part Part

I.

II.

:

Stresses in Simple Trusses Graphic Statics

8vo,

2

8vo,

2

50 50 8vo, 2 50 8vo, 2 50 Oblong 4to, 10 oo

Part III. Bridge Design Part IV. Higher Structures Morison's Memphis Bridge Sondericker's Graphic Statics, with Applications to Trusses, Beams, and Arches. 8vo, WaddelTs De Pontibus, Pocket-book for Bridge Engineers. ..... i6mo, mor, * I2mo, Specifications for Steel Bridges

Waddell and Harrington's Bridge Engineering. (In Preparation.) Wright's Designing of Draw-spans. Two parts in one volume

2 oo 2 oo

50

8vo,

3 50

8vo,

3 oo

HYDRAULICS. Barnes's Ice Formation Bazin's Experiments

.

upon the Contraction

of the Liquid

Vein Issuing from

an Orifice. (Trautwine) Bovey's Treatise on Hydraulics Church's Diagrams of Mean Velocity of Water in Open Channels. Oblong Hydraulic Motors Mechanics of Engineering Coffin's Graphical Solution of Hydraulic Problems Flather's

Dynamometers, and the Measurement

of

Power

8vo,

2 oo

8vo,

5 oo

4to, paper,

8vo,

6 oo

i6mo, mor. i2mo,

3 oo

,

.

8vo,

Water-power Fuertes's Water and Public Health

8vo,

Frizell's

Works

Ganguillet and Kutter's General Formula for the Uniform Flow of Rivers and Other Channels. CHering and Trautwine)

Hazen's Clean Water and

How

to

Get

ft

50

2 oo

Folwell's Water-supply Engineering

Water-filtration

i

8vo,

i2mo, i2mo, Water in 8vo,

Large i2mo,

Filtration of Public Water-supplies Hazlehurst's Towers and Tanks for Water- works

8vo, 8vo,

2

50

4 oo 5 oo i 50 2 50

4 oo i

50

3 oo 2 50

Herschel's 115 Experiments on the Carrying Capacity of Large, Riveted, Metal

Conduits

8vo,

2

oo

Hoyt and Grover's River Discharge 8vo, 2 oo Hubbard and Kiersted's Water-works Management and Maintenance 8vo, 4 oo * Lyndon's .8vo, 3 oo Development and Electrical Distribution of Water Power. Mason's Water-supply. (Considered Principally from a Sanitary Standpoint.) .

.

8vo,

4 oo 5 oo

.8vo,

4 oo

Rvo,

2 oo

8vo,

Merriman's Treatise on Hydraulics * Michie's Elements of Analytical Mechanics * Molitor's Hydraulics of Rivers, Wefrs and Sluices Schuyler's Reservoirs for Irrigation, Water-power,

,.

.

and Domestic Water-

Large 8vo, 5 oo supply * Thomas and Watt's Improvement of Rivers 4to, 6 oo Turneaure and Russell's Public Water-supplies 8vo, 5 oo Wegmann's Design and Construction of Dams. 5th Ed., enlarged .... 4*0, 6 oo Water-supply of the City of New York from 1658 to 1895 4fo, 10 oo Large i2tno, i oo Whtpple's Value of Pure Water Williams and Hazen's Hydraulic Tables 8vo, i 50 .Small 8vo, 4 oo Wilson's Irrigation Engineering Wolff's Windmill as a Prime Mover 8vo, 3 oo Wood's Elements of Analytical Mechanics .8vo, 3 oo Turbines 8vo, 2 50 ;

8

MATERIALS OF ENGINEERING. Baker's Roads and Pavements Treatise on Masonry Construction. . . , Birkmire's Architectural Iron and Steel Compound Riveted Girders as Applied in Buildings Black's United States Public Works

8vo 8vo, 8vo.

3 50

Oblong 410,

5 oo

(In Preparation.) Bleininger's Manufacture of Hydraulic Cement. * Bovey's Strength of Materials and Theory of Structures

Workmanship Employed

2 oo

8vo, 8vo,

Burr's Elasticity and Resistance of the Materials of Engineering Byrne's Highway Construction

Inspection of the Materials and

5 oo 5 oo

8vo,

.

7.

8vo,

3 oo 6 oo

Small 4to,

7 50

i6mo, Church's Mechanics of Engineering Du Bois's Mechanics of Engineering. Vol. I. Kinematics, Statics, Kinetics

>.

50

7 50 5 oo

8vo, in Construction.

The Stresses in Framed Structures, Strength of Materials and Email 4to, 10 oo Theory of Flexures *Eckel's Cements, Limes, and Plasters 8vo, 6 oo Stone and Clay Products used in Engineering. (In Preparation.) Vol.

II.

'.

Fowler's Ordinary Foundations

8vo, 8vo,

.'

Graves's Forest Mensuration

Green's Principles of American Forestry * Greene's Structural Mechanics

3 50 4 oo

i2mo,

i

8vo,

2

50 50

Holly and Ladd's Analysis of Mixed Paints, Color Pigments and Varnishes Large i2mo, 2 50 Johnson's (C. M.) Chemical Analysis of Special Steels. (In Preparation.) Johnson's ( J. B.) Materials of Construction Large 8vo, 6 oo Keep's Cast Iron 8vo, 2 50 Kidder's Architects and Builders' Pocket-book i6mo, 5 oo Lanza's Applied Mechanics 8vo, 7 50 Maire's Modern Pigments and their Vehicles i2mo, 2 oo Martens's Handbook on Testing Materials. (Henning) 2 vols 8vo, 7 50 Maurer's Technical Mechanics 8vo, 4 oo Merrill's Stones for Building and Decoration 8vo, 5 oc Merriman's Mechanics of Materials 8vo, 5 oo * lamo, i oo Strength of Materials I2mo, 2 oo Metcalf's SteeL A Manual for Steel-users .

.

-

Morrison's Highway Engineering Patton's Practical Treatise on Foundations Rice's Concrete Block Manufacture

8vo,

2 50

8vo,

5 oo 2 oo

8vo,

8vo Richardson's Modern Asphalt Pavements lOmo, mor. Richey's Handbook for Superintendents of Construction * Ries's Clays: Their Occurrence, Properties, and Uses 8vo, 8vo, Sabin's Industrial and Artistic Technology of Paints and Varnish * Schwarz's Longleaf Pine in Virgin Forest.., Snow's Principal Species of Wood

Spalding's Hydraulic

Cement

a oo

4 oo 5 oo 3

oo

"mo,

I

25

8vo

3

5<>

I2mo

2

izmo, Text-book on Roads and Pavements .8vo, Plain and Reinforced. Taylor and Thompson's Treatise on Concrete, 8vo, Thurston's Materials of Engineering. In Three Parts 8vo, Parti. Non-metallic Materials of Engineering and Metallurgy 8vo, Part TI. Iron and Steel their Part III- A Treatise on Brasses, Bronzes, and Other Alloys and 8vo Constituents

2

8vo, Tilbon's Street Pavements and Paving Materials Turneaure and Maurer's Principles of Reinforced Concrete Construction.. .8vo, Waterbury's Manual of Instructions for the Use of Students in Cement Labora-

4 oo

.

.

.

.

>

tory Practice.

(.In

Press.)

9

5

8 oo 2 oo 3 50 2 SO 3

oo

Wood's (De V.) Treatise on the Resistance of Materials, and an Appendix on the Preservation of Timber 8vo, Wood's (M. P.) Rustless Coatings: Corrosion and Electrolysis of Iron and Steel

Svo,

2

oo

4 oo

RAILWAY ENGINEERING. Andrews's Handbook for Street Railway Engineers 3x5 inches, mor. .4to, Berg's Buildings and Structures of American Railroads Brooks's Handbook of Street Railroad Location i6mo, mor. Butt's Civil Engineer's Field-book i6mo, mor. Crandall's Railway and Other Earthwork Tables Svo, Transition Curve i6mo, mor. * Crockett's Methods for Earthwork Computations Svo, i6mo mor. Dawson's "Engineering" and Electric Traction Pocket-book .

.

i

25

5 oo

5 oo Dredge's History of the Pennsylvania Railroad: (1879) Paper, 5 oo Fisher's Table of Cubic Yards Cardboard, 25 Godwin's Railroad Engineers' Field-book and Explorers' Guide. i6mo, mor. 2 50 Hudson's Tables for Calculating the Cubic Contents of Excavations and Emr

.

.

bankments Svo, Ives and Hilts's Problems in Surveying, Railroad Surveying and Geodesy i6mo, mor. i6mo, i6mo, mor. i6mo, mor.

Manual for Resident Engineers Nagle's Field Manual for Railroad Engineers Philbrick's Field Manual for Engineers Raymond's Railroad Engineering. 3 volumes. Molitor and Beard's

Railroad Field Geometry. (In Preparation.) Elements of Railroad Engineering Vol. III. Railroad Engineer's Field Book. (In Preparation.) Vol.

I.

Vol.

II.

Searles's Field Engineering

Svo,

i6mo, mor.

Railroad Spiral i6mo, mor. Svo, Taylor's Prismoidal Formulae and Earthwork Field of Practice Out Circular *Trautwine's Curves for Railroads. Laying *

Method of Calculating the Cubic Contents ments by the Aid of Diagrams Webb's Economics of Railroad Construction

of

oo

50 oo 3 oo 3 oo i i

3

50

3 oo i i

50 50

I2mo. mor. Excavations and Embank-

2 50

Svo,

2 oo

Railroad Construction Wellington's Economic Theory

i

of the Location of Railways

Large 12 mo, i6mo, mor. Small Svo,

5 oo

Svo, Svo,

3 oo

2

50

5 oo

DRAWING. Barr's Kinematics of Machinery * Bartlett's

"

*

Mechanical Drawing Abridged Ed

Coolidge's

Manual

of

Drawing

Svo,

i

Svo, paper,

i

Coolidge and Freeman's Elements of General Drafting for Mechanical Engineers Oblong 4to, Durley's Kinematics of Machines Emch's Introduction to Projective Geometry and

Svo, its

Applications

Text-book on Shades and Shadows, and Perspective Jamison's Advanced Mechanical Drawing Elements of Mechanical Drawing

Hill's

Jones's

2 50

Svo,

Svo, Svo, Svo,

50 oo

2 50 4 oo 2 50 2 oo 2 oo

2 50

Machine Design:

Kinematics of Machinery Form, Strength, and Proportions of Parts MacCord's Elements of Descriptive Geometry. Kinematics; or, Practical Mechanism Mechanical Drawing Part Part

I.

II.

Velocity Diagrams

Svo, Svo, Svo, Svo, 4to , Svo,

10

i 50 3 oo 3 oc 5 oo

4 oo i 50

McLeod's Descriptive Geometry Large i2mo, * Mahan's Descriptive Geometry and Stone-cutting 8vo, Industrial Drawing. 8vo, (Thompson) 8vo, Moyer's Descriptive Geometry and Reed's Topographical Drawing 4to Sketching in Mechanical Course Reid's 8vo, Drawing Text-book of Mechanical Drawing and Elementary Machine Design. 8vo, Merrill's

*

(A.

2

5 2

8vo,

2 50

8vo, Oblong 8vo,

3 oo

(McMillan)

W.) and Marx's Machine Design Titsworth's Elements of Mechanical Drawing

Smith

3

50 50 50 oo oo oo oo oo oo

8vo, 8vo,

Elements of Mechanism

Smith's (R. S.) Manual of Topographical Drawing.

i

3 3 3

Robinson's Principles of Mechanism

Schwamb and

i

Warrgn's Drafting Instruments and Operations Elements of Descriptive Geometry, Shadows, and Perspective Elements of Machine Construction and Drawing Elements of Plane and Solid Free-hand Geometrical Drawing General Problems of Shades and Shadows Manual of Elementary Problems in the Linear Perspective of

i2mo, 8vo, 8vo,

i2mo, 8vo,

25 25 3 50 7 50 i oo 3 oo i

i

Form and oo

Shadow i2mo, Manual of Elementary Projection Drawing i2mo, Plane Problems in Elementary Geometry i2mo, 8vo, Problems, Theorems, and Examples in Descriptive Geometry (Hermann and Weisbach's Kinematics and Power of Transmission.

50 25 2 50 i i

8vo,

5 oo

8vo, 8vo,

3 50

8vo,

2 50

Large 8vo,

3 oo

Klein) Wilson's (H. M.) Topographic Surveying Wilson's (V. T.) Free-hand Lettering

Free-hand Perspective Woolf's Elementary Course in Descriptive Geometry

i

i

oo

ELECTRICITY AND PHYSICS. * Abegg's

i2mo, Theory of Electrolytic Dissociation, (von Ende) Andrews's Hand-Book for Street Railway Engineering ....3X5 inches, mor. Large i2mo, Anthony and Brackett's Text-book of Physics. (Magie) .I2mo, Anthony's Lecture-notes on the Theory of Electrical Measurements.

i

Benjamin's History of Electricity

8vo, 8vo,

3 3

8vo, (Boltwood). .8vo,

4

.

Voltaic Cell

Betts's Lead Refining and Electrolysis Classen's Quantitative Chemical Analysis by Electrolysis. * Collins's Manual of Wireless Telegraphy

Crehore and Squier's Polarizing Photo-chronograph * Danneel's Electrochemistry. (Merriam) Dawson's "Engineering" and Electric Traction Pocket-book

i2mo, Mor. 8vo, I2tno, .

.

Dolezalek's Theory of the Lead Accumulator (Storage Battery),

Duhem's Thermodynamics and Chemistry. (Burgess) Flather's Dynamometers, and the Measurement of Power Gilbert's De Magnete. (Mottelay) * Hanchett's Alternating Currents

Bering's Ready Reference Tables (Conversion Factors) * Hobart and Ellis's High-speed Dynamo Electric Machinery Holman's Precision of Measurements

Telescopic Mirror-scale Method, Adjustments, * Karapetoff's Experimental Electrical Engineering

.

.

.

i6ino, mor.

50

i

2 oo

3 oo i 25 5 oo

i2mo,

2 50

8vo, 121110,

4 oo 3 oo

.8vo,

2 50

I2mo, i6mo, mor.

2 50

8vo,

8vo,

I

oo

6 oo 2 oo

,

8vo, 8vo, 8vo,

Burgess). .i2mo, 8vo, (Lorenz) Lob's Electrochemistry of Organic Compounds. * London's Development and Electrical Distribution of Water Tower 8vo,

11

i

3

(von Ende)

and Tests .... Large 8vo

Kinzbrunner's Testing of Continuous-current Machines. Landauer's Spectrum Analysis. (Tingle) Le Chatelier's High-temperature Measurements. (Boudouard

3

25 25 oo oo oo oo oo oo

i

6

75 oo

2 oo

3 3 3 3

09 oo oo oo

* Lyons's Treatise on Electromagnetic Phenomena. Vols. I. and II. 8vo, each, * Michie's Elements of Wave Motion Relating to Sound and -Light 8vo, I2mo, Morgan's Outline of the Theory of Solution and its Results * I2mo, Physical Chemistry for Electrical Engineers

6 oo 4 oo I oo

50

i

(Fishback). .I2mo, 2 50 Niaudet's Elementary Treatise on Electric Batteries. * Norris's Introduction to the Study of Electrical Engineering 8vo, 2 50 * Parshall and Hobart's Electric Machine Design 4to, half mor. 12 50 New Edition. Reagan's Locomotives: Simple, Compound, and Electric. .

.

Large i2mo, 3 50 .8vo, 2 co

* Rosenberg's Electrical Engineering. (Haldane Gee Kinzbrunner). Ryan, Norris, and Hoxie's Electrical Machinery. Vol. 1

.

.

8vo,

2 50

i2mo, Swapper's Laboratory Guide for Students in Physical Chemistry * Tollman's Elementary Lessons in Heat 8vo, Large i2mo, Tory and Pitcher's Manual of Laboratory Physics. Ulke's Modern Electrolytic Copper Refining 8vo,

oo 50 2 oo 3 oo i

i

LAW. * Davis's Elements of Law * Treatise on the Military

,

Law

of United States

* * Dudley's Military Law and the Procedure of Courts- martial Manual for Courts-martial

.

.

.

2

8vo,

7 oo

Sheep, .Large 12 mo, i6mo, mor.

Wait's Engineering and Architectural Jurisprudence

Law Law

8vo,

8vo,

Sheep, of Contracts 8vo, of Operations Preliminary to Construction in Engineering and Archi-

8vo

tecture

Sheep,

50

7 50 2

50 50 6 oo 6 50 3 oo i

5 oo 5 50

MATHEMATICS. Baker's Elliptic Functions Briggs's Elements of Plane Analytic Geometry. (Bocher) *Buchanan's Plane and Spherical Trigonometry Byerley's Harmonic Functions Chandler's Elements of the Infinitesimal Calculus

Compton's Manual

of

8vo,

i

50

i2mo,

i

8vo,

i

oo oo

8vo,

Logarithmic Computations

i2mo,

50 50 i 25 2 50

8vo, size, paper,

100 copies, *

Mounted on heavy cardboard, 8 X 10 inches, 10 copies,

Johnson's (W. W.) Abridged Editions of Differential and Integral Calculus Large i2mo, i vol. Curve Tracing in Cartesian Co-ordinates I2mo, Differential Equations Elementary Treatise on Differential Calculus

*

'.

Elementary Treatise on the Integral Calculus Theoretical Mechanics Theory of Errors and the Method of Least Squares Treatise on Differential Calculus Treatise on the Integral Calculus Treatise on Ordinary and Partial Differential

12

.

oo oo

2

* Dickson's College Algebra Large i2mo, * Introduction to the Theory of Algebraic Equations Large i2mo, Emch's Introduction to Projective Geometry and its Applications 8vo, Fiske's Functions of a Complex Variable 8vo, Halsted's Elementary Synthetic Geometry 8vo, of Elements Geometry 8vo, * Rational Geometry i2mo,

Hyde's Grassmann's Space Analysis * Jonnson's (J- B.) Three-place Logarithmic Tables: Vest-pocket

i

i2mo,

i i

i i

i i

i

oo 50 75 50 oo

15 5 oo

25 2 oo 2 50

8vo,

i

oo oo

.*Large I2mo, Large I2mo,

I

50

I

50

I2mo, I2mo, Large i2mo, Large i2mo, Equations. Large I2mo, .

i

3 oo i

50

3 oo 3 oo 3 50

'

Laplace's Philosophical Essay on Probabilities. (Truscott and Emory). .12010, * Ludlow and Bass's Elements of Trigonometry and Logarithmic and Other 8vo, Tables Each, Trigonometry and Tables published separately * Ludlow's Logarithmic and Trigonometric Tables 8vo,

2

j oo 2 i

Macfarlane's Vector Analysis and Quaternions

8vo,

i

McMahon's Hyperbolic Functions Manning's Irrational Numbers and

8vo,

i

their Representation

Series

by Sequences and I2mo,

Mathematical Monographs. Edited by Mansfield Merriman and Robert Octavo, each S. Woodward No. i. History of Modern Mathematics, by David Eugene Smith. NQ. No.

2.

3.

oo

oo oo oo oo

i

25

i

oo

Synthetic Projective Geometry, by George Bruce Halsted. Determinants, by Laenas Gifford Weld. No. 4. Hyper-

No. 5. Harmonic FuncFunctions, by James McMahon. by William E. Byerly. No. 6. Grassmann's Space Analysis, by Edward W. Hyde. No. 7. Probability and Theory of Errors, by Robert S. Woodward. No. 8. Vector Analysis and Quaternions, by Alexander Macfarlane. No. 9. Differential Equations, by William Woolsey Johnson. No. 10. The Solution of Equations, by Mansfield Merriman. No. n. Functions of a Complex Variable, by Thomas S. Fiske. Maurer'a Technical Mechanics 8vo, 4 oo Merriman's Method of Least Squares 8vo, 2 oo Solution of Equations 8vo, i oo Rice and Johnson's Differential and Integral Calculus. 2 vols. in one. Large i2mo, i 50 Elementary Treatise on the Differential Calculus Large i2mo, 3 oo Smith's History of Modern Mathematics 8vo, i oo * Veblen and Lennes's Introduction to the Real Infinitesimal Analysis of One bolic

tions,

Variable * Waterbury's Vest Pocket

8vo,

Hand-Book

of Mathematics for Engine 2

Xst

inches, mor.

Weld's Determinations Wood's Elements of Co-ordinate Geometry Woodward's Probability and Theory of Errors

2

oo

rs.

8vo, 8vo, 8vo,

oo co 2 oo i oo i

i

MECHANICAL ENGINEERING. MATERIALS OF ENGINEERING, STEAM-ENGINES AND BOILERS. Bacon's Forge Practice Baldwin's Steam Heating for Buildings Bair's Kinematics of Machinery * Bartlett's Mechanical Drawing " " * Abridged Ed Benjamin's Wrinkles and Recipes * Burr's Ancient and Modern Engineering and the Isthmian Canal Carpenter's Experimental Engineering Heating and Ventilating Buildings

i2mo, i2mo,

50

8vo, 8vo,

3 oo

8vo,

i

50

i2mo,

2 oo

8vo,

3 50 6 oo

8vo, 8vo,

Gas and Oil Engine Large i2mo, Compton's First Lessons in Metal Working i2mo, Groodt's Lathe and De Speed Compton i2mo, Manual of Drawing Coolidge's 8vo, paper, Coolidge and Freeman's Elements of General Drafting for Mechanical Engineers Oblong 4to, Cromwell's Treatise on Belts and Pulleys i2mo, Treatise on Toothed Gearing i2mo, of Machines Kinematics Durley's 8vo, 13 Clerk's

i

2 50 2 50

4 oo 4 oo

;

50 So 50 4 oo

Dynamometers and Rope Driving

Flather's Gill's

the

Measurement

of

Power,

Gas and Fuel Analysis for Engineers Locomotive Sparks

Goss';}

Greene's Hering's

i2mo, i2mc, i2mo,

...

Hobart and Ellis's High Speed Dynamo Electric Machinery Button's Gas Engine Jamison's Advanced Mechanical Drawing Elements of Mechanical Drawing Jones's Machine Design: Part I. Kinematics of Machinery Part II. Form, Strength, and Proportions of Parts Kent's Mechanical Engineers' Pocket-book Kerr's Power and Power Transmission Leonard's Machine Shop Tools and Methods'

2 50

8vo.

6 oo

Svo,

Svo, 8vo, 8vo, 8vo,

.

.

.

8vo, 8vo, 4to,

8vo, 8vo, 8vo,

Small 4to, half leather, 8vo,

50 oo>

5 oo-

4 oo i 50 i 50 3 5012 50 3 oo 3 oo 3 oo

8vo,

2 oo 3 oo i 50 3 oo 3 oo 3 oo 3 oo

(Woodward and Preston) Large 12010,

3 oo

Robinson's Principles of Mechanism

8vo, 8vo,

Elements of Mechanism

Smith's (O.) Press- working of Metals

8vo,

Smith (A. W.) and Marx's Machine Design Combustion in Alcohol Engines .

i

3

2 oo 4 oo 4 oo

8vo, 8vo, 8vo, Text-book of Mechanical Drawing and Elementary Machine Design. 8vo, Richard's Compressed Air i2mo,

' Sorel s Carbureting and

50

8vo,

* Porter's Engineering Reminiscences, 1855 to 1882 Reid's Course in Mechanical Drawing

Merrill's

2

5 oo

Modern Refrigerating Machinery. (Pope, Haven, .and Dean) MacCord's Kinematics; or, Practical Mechanism Mechanical Drawing Velocity Diagrams

MacFarland's Standard Reduction Factors for Gases

5 co 2 oo

i6mo, mor. 8vo,

* Lorenz's

Schwamb and

25

oo

i6mo, mor.

*

Mahan's Industrial Drawing. (Thompson) * Parshall and Hobart's Electric Machine Design Peele's Compressed Air Plant for Mines Poole's Calorific Power of Fuels

i

2

8vo,

.

Pumping Machinery. (In Preparation.) Ready Reference Tables (Conversion Factors)

3 oo 2 oo

.

Thurston's Animal as a Machine and Prime Motor, and the Laws of Energetics.

i2mo, on Friction and Lost Work in Machinery and Mill Work... 8vo, Tillson's Complete Automobile Instructor i6mo, mor. * Titsworth's Elements of Mechanical Drawing Oblong 8vo, Warren's Elements of Machine Construction and Drawing 8vo, * Waterbury's Vest Pocket Hand Book of Mathematics for Engineers. Treatise

2|X Si Weisbach's

Kinematics

and the Power

of

Transmission.

inches, mor.

i

oo

3 oo 2

50 oo

i

25

i

7 50 i

oo

(Herrmann 8vo,

5 oo

Klein).. .8vo,

8vo,

5 oo 2 50

8vo,

7 50

8vo, 8vo,

7 50 6 oo

Svo, Holley and Ladd's Analysis of Mixed Paints, Color Pigments, and Varnishes.

2 50

Klein)

Machinery of Transmission and Governors. Wood's Turbines.

(Herrmann

MATERIALS OF ENGINEERING. *

Bovey's Strength of Materials and Theory of Structures Burr's Elasticity and Resistance of the Materials of Engineering

Church's Mechanics of Engineering * Greene's Structural Mechanics

Large i2mo, Johnson's Materials of Construction Keep's Cast Iron Lanza's Applied Mechanics

Svo, Svo, 8vo,

14

2

50 6 oo

2 50

7 50

Modern Pigments and their Vehicles Martens 's Handbook on Testing Materials. (Henning) Maurer's Technical Mechanics Merriman's Mechanics of Materials

12010,

*

I2mo, i2mo,

Maire's

Strength of Materials A Manual for Steel-users Metcalf 's Steel.

and Artistic Technology Smith's Materials of Machines Sabin's Industrial

of Paints

oo

7 50

8vo, 8vo,

4 oo 5 oo i oo 2 oo 3 oo i oo 8 oo 2 oo

and Varnish

8vo,

I2mo,

Thurston's Materials of Engineering 3 vols., 8vo, Part I. Non-metallic Materials of Engineering and Metallurgy. .8vo, Part II. Iron and Steel 8vo, Part III. A Treatise on Brasses, Bronzes, and Other Alloys and their Constituents 8vo, .

Wood's (De V.) Elements of Analytical Mechanics 8vo, Treatise on the Resistance of Materials and an Appendix on the Preservation of Timber 8vo, Wood's (M. P.) Rustless Coatings: Corrosion and Electrolysis of Iron and Steel

2

8vo,

3 50 2 50 3 oo

2 oo

8vo,

4 oo

i2ino,

25 50 2 50

STEAM-ENGINES AND BOILERS. Berry's Temperature-entropy Diagram Carnot's Reflections on the Motive Power of Heat. Chase's Art of Pattern Making

i2mo, I2mo,

(Thurston)

Creighton's Steam-engine and other Heat-motors Dawson's "Engineering" and Electric Traction Pocket-book Ford's Boiler Making for Boiler Makers Gebhardt's Steam Power Plant Engineering. (In Press.)

8vo,

500

i6mo, mor. i8mo,

5 oo

Goss's Locomotive Performance

Hemenway's Indicator

i

i

i

oo

8vo, 5 oo

Practice and Steam-engine

Economy

Button's Heat and Heat-engines Mechanical Engineering of Power Plants Kent's Steam boiler Economy Kneass's Practice and Theory of the Injector

i2mo,

2 oo

8vo,

5 oo

8vo, 8vo,

5 oo

8vo, 8vo,

4 oo i 50 2 oo

MacCord's Slide-valves Meyer's Modern Locomotive Construction 4to, 10 oc Moyer's Steam Turbines. (Tn Press.) Peabody's Manual of the Steam-engine Indicator i2mo, i 50 Tables of the Properties of Saturated Steam and Other Vapors 8vo, i oo Thermodynamics of the Steam-engine and Other Heat-engines 8vo, 5 oo Valve-gears for Steam-engines 8vo, 2 50 8vo, 4 oo Peabody and Miller's Steam-boilers Pray's Twenty Years with the Indicator Large 8vo, 2 50 Pupin's Thermodynamics of Reversible Cycles in Gases and Saturated Vapors. .

.i2mo,

(Osterberg)

Reagan's Locomotives: Simple, Compound, and Electric.

New

Locomotive Engine Running and Management Smart's Handbook of Engineering Laboratory Practice Snow's Steam-boiler Practice Spangler's Notes on Thermodynamics Sinclair's

,

Thomas's Steam-turbines Engine and Boiler Thurston's Handbook cator and the Prony Brake

Handy Manual

3 50 2 oo

i2mo,

2 50

8vo,

3 oo i oo 2 50 3 oo

,

8vo,

8vo, 8vo, Trials, and the Use of the Indi-

4 oo

8vo,

5 oo

:

o>

Tables

8vo,

of Steam-boilers, their resigns, Construction,

15

23

Large i2mo, i2mo,

i2mo,

Valve-gears Spangler, Greene, and Marshall's Elements o Steam-engineering

i

Edition.

and Operation..8vo,

i

50

5 oo

Thurston's Manual of the Steam-engine 2 vols., 8vo, 10 oo Part I. History, Structure, and Theory 6 oo 8v:>, Part II. Design, Construction, and Operation 8vo, 6 oo Steam-boiler Explosions in Theory and in Practice i2mo, i 50 Wehrenfenning's Analysis and Softening of Boiler Feed-water (Patterson) 8vo, 4 oo Weisbach's Heat, Steam, and Steam-engines. (Du Bois) 8vo, 5 oo

Whitham's Steam-engine Design Wood's Thermodynamics, Heat Motors, and Refrigerating Machines

8vo, 8vo,

5 oo 4 oo

Church's Mechanics of Engineering 8vo, Notes and Examples in Mechanics 8vo, Dana's Text-book of Elementary Mechanics for Colleges and Schools. .i2mo, Du Bois's Elementary Principles of Mechanics: I. Vol. Kinematics 8vo,

6 oo 2 oo

.

.

.

MECHANICS PURE AND APPLIED.

VoL

II.

Mechanics

Statics

8vo,

of Engineering.

Vol.

i

50

3 50

400

Small 4to, 7 50 Small 4to, 10 oo

I

Vol. II.

*Greene's Structural Mechanics 8vo, 2 50 James's Kinematics of a Point and the Rational Mechanics of a Particle. Large I2mo, 2 oo * Johnson's (W. W.) Theoretical Mechanics i2mo, 3 oo Lanza's Applied Mechanics 8vo, 7 So * Martin's Text Book on Mechanics, Vol. I, Statics i2mo, i 25 * Vol. 2, Kinematics and Kinetics .i2mo, 1 50 Maurer's Technical Mechanics 8vo, 4 oo * Merriman's Elements of Mechanics I2mo, i oo Mechanics of Materials 8vo, 5 oo * Michie's Elements of Analytical Mechanics 8vo, 4 oo of Mechanism Robinson's Principles 8vo, 3 oo Problems Sanborn's Mechanics Large I2mo, i 50 Schwamb and Merrill's Elements of Mechanism 8vo, 3 oo Wood's Elements of Analytical Mechanics 8vo, 3 oo lamo, i 25 Principles of Elementary Mechanics .

MEDICAL. * Abderhalden's Physiological Chemistry in Thirty Lectures.

(Hall and Defren)

8vo,

von Behring's Suppression * Bolduan's

Immune

of Tuberculosis.

i2mo, i2mo,

(Bolduan)...

Sera

5 oo i

oo 50

i

50

i

Davenport's Statistical Methods with Special Reference to Biological Varia-

i6mo, mor.

tions

Ehrlich's Collected Studies on Immunity. (Bolduan) 8vo, * Fischer's Physiology of Alimentation Large i2mo, cloth, de Fursac's Manual of Psychiatry. (Rosanoff and Collins) Large i2mo,

6 oo

* Pauli's Physical Chemistry in the Service of Medicine. (Fischer) * Pozzi-Escot's Toxins and Venoms and their Antibodies. (Cohn) Rostoski's Serum Diagnosis. (Bolduan).

25 oo i oo 2 oo i oo 2 50

2

oo

2

50 Hammarsten's Text-book on Physiological Chemistry. (Mandel) 8vo, 4 oo Jackson's Directions for Laboratory Work in Physiological Chemistry. ..8vo, i 25 Lassar-Cohn's Practical Urinary Analysis. i2mo, i oo (Lorenz) Mandel's Hand Book for the Bio-Chemical Laboratory I2mo, i 50

'.

Ruddiman's Incompatibilities

Whys

in

in Prescriptions

,

i2mo, i2mo, I2mo, 8vo,

I2mo,

Pharmacy

Salkowski's Physiological and Pathological Chemistry. (Orndorff) * Satterlee's Outlines of Human Embryology Smith's Lecture Notes on Chemistry for Dental Students

16

8vo,

I2mo, 8vo,

i i

i 25 2 50

Steel's Treatise on the Diseases of the * Whipple's Typhoid Fever Woodhull's Notes on Military Hygiene * Personal

Dog

8vo,

Large i2mo, i6mo, Hygiene i2mo, Small and Atkinson's Worcester Hospitals Establishment and Maintenance, for arid S ggestions Hospital Architecture, with Plans for a SmaU i2mo, Hospital

3 50 3 oo i

50 oo

i

25

i

METALLURGY. Betts's

Lead Refining by

Electrolysis Holland's Encyclopedia of Founding in the Practice of Moulding

8vo,

and Dictionary

Foundry Terms Used i2mo, Iron Founder i2mo, " " Supplement i2mo, Douglas's Untechnical Addresses on Technical Subjects i2mo, Goesel's Minerals and Metals: A Reference Book i6mo, mor. * Iles's Lead-smelting i2mo, Keep's Cast Iron Le Chatelier's High-temperature Measurements. (Boudouard Metcalf's Steel.

A Manual

4 oo

of

3 oo 2 50 2 50 i

oo

3 oo 2 50

8vo,

2 50

Burgess) 12010,

3 oo 2 oo

for Steel-users

Cyanide Process Minet's Production of Aluminium and itsjndustrial Use. (Waldo) Robine and Lenglen's Cyanide Industry. (Le Clerc) Ruer's Elements of Metallography. (Mathewson) (In Press.) Smith's Materials of Machines

i2mo, i2mo,

Miller's

.

.

.i2mo, 8vo,

i2mo,

Thurston's Materials of Engineering. In Three Parts 8vo, Part I. Non-metallic Materials of Engineering and Metallurgy 8vo, Part II. Iron and Steel 8vo, Part HI. A Treatise on Brasses, Bronzes, and Other Alloys and their Constituents 8vo, Ulke's Modern Electrolytic CopperRefining 8vo, West's American Foundry Practice ! i2mo, Moulder's Text Book i2mo, Wilson's Chlorination Process 12 mo, Cyanide Processes ramo, .

.

.

'.

i

oo

2

50 4 oo i oo 8 oo

2

oo

3 50 2 50

3 oo 2 50 2

'

i i

50 50 50

MINERALOGY. Barringer's Description of Minerals of Commercial Va!ue

Oblong, mor. Boyd's Resources of Southwest Virginia 8vo, .Pocket-book form. Boyd's Map of Southwest Virginia * Browning's Introduction to the Rarer Elements 8vo, Brush's Manual of Determinative Mineralogy. (Penfield) 8vo, Butler's Pocket Hand-Book of Minerals i6mo, mor. Chester's Catalogue of Minerals 8vo, paper, Cloth, * Crane's Gold and Silver

8vo,

2 50 3

oo

2

oo

i 50 4 oo 3 oo i oo

i

25

5 oo

"

Dana's First Appendix to Dana's New System of Mineralogy. ." .Large 8vo, i oo 2 oo zarno Manual of Mineralogy and Petrography i2mo, I 50 Minerals and How to Study Them Large 8vo, half leather, 12 50 System of Mineralogy 8vo, 4 oo Text-book of Mineralogy i2mo, i oo Douglas's Untechnical Addresses on Technical Subjects 8vo, i 25 Eakle's Mineral Tables ( In Preparation. ) Stone and Clay Products Used in Engineering .

.

Egleston's Catalogue of Minerals and Synonyms Goesel's Minerals and Metals : A Reference Book Groth's Introduction to Chemical Crystallography (Marshall)

17

8vo,

2 50

i6mo, mor. i2mo,

3 op i

25

* Iddings's Rock Minerals 8vo, 8vo, Johannsen's Determination of Rock-forming Minerals in Thin Sections * Martin's Laboratory Guide to Qualitative Analysis with the Blowpipe. 12010, Merrill's Non-metallic Minerals: Their Occurrence and Uses 8vo, Stones for Building and Decoration 8vo, * Penfield's Notes on Determinative Mineralogy and Record of Mineral Tests. 8vo, paper, Tables of Minerals, Including the Use of Minerals and Statistics of Domestic Production Svo, * Pirsson's Rocks and Rock Minerals I2mo, * Richards's Synopsis of Mineral Characters.. I2mo, mor. * Ries's Clays: Their Occurrence, Properties, and Uses 8vo, * Tillman's Text-book of Minerals and Rocks 8vo, Important

5 oo 4 oo 60

4 oo

500 50 i

oo

2

50 25 oo 5 2 oo i

MINING. * Beard's Mine Gases and Explosions Boyd's Map of Southwest Virginia. Resources of Southwest Virginia * Crane's Gold and Silver Douglas's Untechnical Addresses on Technical Subjects Eissler's Modern High Explosives A Reference Book , Goesel's Minerals and Metals :

.

.

Lar^e i2mo, Pocket-oook rorm 8vo, 8vo,

i2mo Svo,

i6mo, mor.

,

Ihlseng's Manual of Mining * Iles's Lead-smelting

8vo,

Cyanide Process O'Driscoll's Notes on the Treatment of Gold Ores Peele's Compressed Air Plant for Mines Riemer's Shaft Sinking Under Difficult Conditions. (Corning and Peele) Robine and Lenglen's Cyanide Industry. (Le Clerc) * Weaver's Military Explosives Wilson's Chlorination Process Miller's

.

'

2

oo

3 oo 5 oo r oo 4 oo 3 oo 5 oo

I2mo, i2mo,

2

so

i

Svo,

2

oo oo oo oo oo oo so 50 50 25

.

Cyanide Processes Hydraulic and Placer Mining. 2d edition, rewritten Treatise on Practical and Theoretical Mine Ventilation

3 oo

Svo,

3

.8vo,

3

Svo,

4

Svo,

3

izmo, i2mo, i2mo> 12 mo,

i

i

2 i

SANITARY SCIENCE. /

Association of State and National Food and Dairy Departments, Hartford Meeting,

1906

Svo,

,

Jamestown Meeting, 1907

Svo,

* Bashore's Outlines of Practical Sanitation

i2mo, i2mo, i2mo,

Sanitation of a Country House Sanitation of Recreation Camps and Parks

FolwelTs Sewerage. (Designing, Construction, and Maintenance) Water-supply Engineering Fowler's Sewage Works Analyses Fuertes's Water-filtration Works.. Water and Public Health

Gerhard's Guide to Sanitary House-inspection * Modern Baths and Bath Houses Sanitation of Public Buildings Hazen's Clean Water and How to Get It Filtration of Public Water-supplies

Svo, Svo,

i2mo, I2mo, i2mo, i6mo, Svo, 1 2mo,

Large i2mo,

Svo, Kinnicut, Winslow and Pratt's Purification of Sewage. (In Press.) Leach's Inspection and Analysis of Food with Special Reference to Stats Control Svo,

Mason's Examination of Water.

(Chemical and Bacteriological)

Water-supply. (Considered Principally from a Sanitary Standpoint)

18

3 oc 3 oo i 25 i oo i

oo

3 oo

4 oo 2

oo

2 50

50 oo 3 oo i 50 i 50 3 oo i i

i2mo,

7 oo i 25

Svo,

4 oo

.

.

* Merriman's Elements of Sanitary Engineering..

.

8vo,

.-

nmo, Ogden's Sewer Design Parsons's Disposal of Municipal Refuse 8vo, Prescott and Winslow's Elements of Water Bacteriology, with Special Reference to Sanitary Water Analysis i2mo, * Price's Handbook on Sanitation i2mo, Richards's Cost of Food. A Study in Dietaries 12 mo, Cost of Living as Modified by Sanitary Science 1 21110,

oo

2

2 oo

2 oo

50 50 oo

.

Cost of Shelter

oo oo

i2mo,

* Richards and Williams's Dietary Computer 8va, Richards and Woodman's Air, Wa^rj^aa^Food from a Sanitary Stand-

50

8vo,

oo oo

"

point

.

.

.

,.^<^\^. :vy. of the^nre^vatjojj Fjiod of and Sewage Bacteria'l^ifipdtw*r ^ettage

Rideal's Disinfection

and

Soper's Air and

8vo, 8vo,

Ventilatic^p SuawaJ*. -^/l Turneaure and Russell's Public 'vfQMTj&iptifa.ex. Venable's Garbage Crematjuges u^kmencaQ //. Method and Devices for Bkcte4al)rj^tment of Sewage Ward and Whipple's Freshvliater BiwteySr (In Press. ) .

.

DnnlnSg^ater Whipple's Microscopy * Typhod Fever Value of Pure Water Winslow's Bacterial Classification. (In Press.) Winton's Microscopy of Vegetable Foods

Large 12010, 8vo, 8vo,

8vo,

of

8vo,

Large i2mo, Large i2mo, 8vo,

4 oo 2 50 5 oo 2 oo 3 oo 3 50 3 oo i

oo

7 50

MISCELLANEOUS. Emmons's Geological Guide-book

Rocky Mountain Excursion

of the

International Congress of Geologists Ferrel's Popular Treatise on the Winds Fitzgerald's Boston Machinist Gannett's Statistical Abstract of the

8vo,

i8mo, 24mo, I2mo,

World

Haines's American Railway Management * Hanusek's The Microscopy of Technical Products.

New Testament

3 oo 2 oo 2 oo 2 25 2 oo

12010,

i6mo, 8vo, I2ir o,

i

50

x

23

TEXT-BOOKS.

Small 4to. half mor.

19

75 2 50

Large i2mo, Large 8vo,

Green's Elementary Hebrew Grammar i2tno, Gesenius's Hebrew and Chaldee Lexicon to the Old Testament Scr.ptures. (Tregelles)

50 4 oo i oo

5 oo

Standage's Decoration of Wood, Glass, Metal, etc Thome's Structural and Physiological Botany. (Bennett) Westermaier's Compendium of General Botany. (Schneider) Winslow's Elements of Applied Microscopy

HEBREW AND CHALDEE

i

8vo,

(Winton) Ricketts's History of Rensselaer Polytechnic Institute 1824-1894.

Rotherham's Emphasized

of the

Large 8vo,

5 oo

iff

1

t :

;.''

I

1

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