Chapter III: =THE TEETH OF GEAR-WHEELS (Continued).=

=Gear Teeth=, revolving cutters for 37
Pantagraph engine for dressing the cutters for 38
Numbers of cutters used for a train of wheels 39
=Gear-Wheel Teeth.= Table of equidistant value of cutters 41
Depth of, in the Brown and Sharpe system 42
Cutting the teeth of worm-wheels 42
Finding the angle of the cutter for cutting worm-wheels 43
The construction of templates for rolling the tooth curves 43
Rolling the curves for gear teeth 43
Forms of templates for gear teeth 44
Pivoted arms for tooth templates 44
Marking the curves by hand 45
Former or Template of the Corliss bevel gear-wheel engine or
cutting machine 45
The use of extra circles in marking the curves with compasses 46
Finding the face curves by geometrical constructions 47
The Willis odontograph for finding the radius for striking the
curves by hand 47
The method of using the Willis odontograph 48
Professor Robinson's odontograph 49
Method of using Professor Robinson's odontograph 49
Application of Professor Robinson's odontograph for trains of
gearing 51
Tabular values and setting numbers for Professor Robinson's
odontograph 51
Walker's patent wheel scale for marking the curves of cast
teeth 51
The amount of side clearance in cast teeth 53
Filleting the roots of epicycloidal teeth with radial flanks 53
Scale of tooth proportions given by Professor Willis 54
The construction of a pattern for a spur-wheel that is to be
cast with the teeth on 54
Template for planing the tooth to shape 54
Method of marking the curves on teeth that are to be glued on 55
Method of getting out the teeth of 56
Spacing the teeth on the wheel rim 56
Methods of accurately spacing the pattern when it has an even
number of teeth 58
Method of spacing the wheel rim when it has an odd number of
teeth 58
=Gear-Wheels, Bevel Pinion=, drawings for 59
Getting out the body for a bevel-wheel 59
Template for marking the division lines on the face of the
wheel 59
Marking the lines of the division on the wheel 60
=Gear-Wheels, Pinion=, with dovetail teeth 60
Testing the angle of bevel-wheels while in the lathe 60
=Gear-Wheels, Skew Bevel.= Finding the line of contact 61
Marking the inclination of the teeth 61
=Gear-Wheels, Bevel=, drawing for built up 61
=Gear-Wheels, Worm=, or endless screw 62
Constructing a pattern from which the worm is to be cast 62
Tools for cutting the worm in a lathe 62
Cutting the teeth by hand 62
=Gear-Wheels, Mortise= or cogged 63
Methods of fastening cogs 63
Methods of getting out cogs for 63
=Gear-Wheel Teeth=, calculating the strength of epicycloidal 64
Factors of safety for 64
Tredgold's rule for calculating the strength of 65
Cut, calculating the strength of 65
=Gear-Wheel Teeth.= The strength of cogs 66
The thickness of cogs 66
The durability of cogs 66
Table for calculating the strength of different kinds of 67
The contact of cast teeth 67
Table for determining the relation between pitch diameter,
pitch, and number of teeth in gear-wheels 68
Examples of the use of the above table 68
With stepped teeth 69
Angular or helical teeth 69
End thrust of angular teeth 69
Herring-bone angular teeth 69
For transmitting motion at a right angle by means of angular or
helical teeth 69
Cutting helical teeth in the lathe 69
For wheels whose shaft axes are neither parallel nor meeting 70
Elliptical 70
Elliptical, marking the pitch lines of 70
Elliptical, drawing the teeth curves of 73
For variable motion 74
Form of worm to give a period of rest 74
Various applications of 74
=Gear-Wheels=, arrangement of, for periodically reversing
the direction of motion 75
Watt's sun and planet motion 75
Arrangements for the rapid multiplication of motion 75
Arrangement of, for the steering gear of steam fire-engines 75
Various forms of mangle gearing 79
=Gear-Wheel and Rack=, for reciprocating motion 77
=Friction Wheels.= 77
The material for 77
Paper 78
For the feed motion of machines 78
The unequal wear upon grooved 79
Form of, for relieving the journals of strain 79
=Cams=, for irregular motion 80
Finding the pitch line of 80
Finding the working face of 80
The effect the diameter roller has upon the motion produced by
a cam 80
Demonstration of the different motion produced by different
diameters of rollers upon the same cam 80
Diagram of motion produced from the same cam with different
diameters of rollers 81
Return or backing 82
Methods of finding the shape of return or backing 82
=Cam Motion=, for an engine slide valve without steam lap 83
For a slide valve with steam lap 83
=Groove Cams=, proper construction of 84
The wear of 84
Brady's improved groove cam with rolling motion and adjustment
for wear 84