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