SPRINGS. 71 



is taken up by a leather washer. On the outer side of the 

 collar another leather washer is placed. A short distance 

 from this point the axle arm bevels down to a smaller diameter 

 and continues in conical shape (diminishing one-eighth of 

 an inch to a foot) to the end. A thread is cut on the end of 

 the axle box and over it the oil cup is screwed. 



The wheel having been put on, a nib or projecting metal 

 point on the back of the hub fits into a hole in the moon 

 plate and retains the latter in a proper position to receive 

 the three iron bolts. On the outer face of the hub an iron 

 plate is placed over these bolts, and firmly held by nuts 

 which screw on to the projecting bolt ends. The other ends 

 of the bolt pass through the moon plate and are there fastened 

 as in front. The metal rim on the back of the hub extends 

 over the rim of the moon plate and thus protects the arm from 

 dust and dirt. The use of the Mail axle is chiefly confined 

 to certain types of sporting vehicles. (See Fig. 38.) 



SPRINGS. 



In the making of good springs skilled workmen are em- 

 ployed to draw the pieces to the required shape and dimen- 

 sions and in tempering and setting them. All this work 

 requires considerable experience and judgment in order to 

 render corresponding parts of the springs of equal resistance. 

 Upon the uniformity of one part with another in the matter 

 of elasticity depends the even resistance and balance of the 

 springs when acted upon by the weight of the body. The 

 best quality steel springs are only made stiff enough to with- 

 stand any strain that may reasonably be expected will be 

 brought to bear upon them. By this method almost the en- 

 tire range of elasticity in the spring is obtained under ordi- 



