TOOTHED wants 



0*7 M-Awfe-ln --. .1 wheels the pitch surtax** are part* 

 of cones. Bevil wheels are used to connect shaft* which an- 

 one another, whereas spur wheels are used to connect 

 parallel shafts. In fig. 46 is shown a pair of bevil wheels in 

 gear, oneof them being a mortise wh ) is a separate 



drawing, to a smaller scale, of the pitch cooes. TV 

 cones are shown on the drawing of the complete wheels by 

 dotted lines. 



diameters of bevil wheels are the diameters of the bases 

 t<li 



ucuuc 46 : /Mir of tori Week. -Draw the sectional eleva- 

 tion of the bevil wheels shown in gear in fig. 46. Commence by 

 drawing the centre lines of the shafts, which in tin* eiample are at 

 right angles to one another ; then draw the pitch eonee shown by 

 dotted lines. Next put in the teeth which eome into the plane of 

 the section, then complete the sections of the wheels. The pinion 

 or smaller wheel has 25 teeth, and the wheel has 50 teeth, which 

 makes the pitch a little over 8 inches. Each tooth of the mortise 

 wheel is secured as shown by an iron pin ,* inch diameter. Scale 

 .; bob - la i t si 



''HANKS ANh OH T8. 



The most important application of the crank is in the 

 steam-engine, where the reciprocating rectilineal motion of 

 is converted into tbe rotary motion of the crank- 

 .ihuft by means of the crank and connecting rod. 



steam-engine cranks were largely made of 

 cast ir hey are always made of wrought iron or steel. 



The crank is either forged in one piece with the shaft, ... it in 



liUk.lr x,.|,.ir.lt.-l\ .mil tin Ii '..< \.-l bQ N 



Ovtrkuny CrtinJi: Fig. 47 sliowi a wrought hung 



crank. A is the crank -shaft, 11 tin- crank arm, provided at 

 one end with a boss ('. * huh is bored out to fit the shaft ; at 

 the other end of the crank arm is a boss D, which is bored out 

 to receive the crank-pin . <rks in one end of the 



connecting rod. The crank is in-cured to the abaft by the 



