TRACTION ENGINES 44! 



travel is allowed to revolve in the bearings instead of the 

 wheels revolving upon the axle. By having the axle re- 

 volve in this manner the wear is all in a straight line and 

 on the top of the boxing, hence there is no reason for the 

 wheels to become wobbly and cut the transmission gear- 



FIG. 321 REAR-MOUNTED ENGINE 



ing unevenly. By referring to Fig. 322 it will be seen 

 that the use of springs becomes impossible on a rear- 

 mounted engine as shown in Fig. 321. Assuming that 

 there are springs in this type of mounting, and that the 



