45O FARM MOTORS 



traction wheel. The intermediate gears are generally 

 attached to the boiler by means of brackets as shown 

 in Fig. 322. If the engine were always to travel 

 straight ahead or straight backward the matter of trans- 

 mission gearing would be very simple, but since it has 

 to turn and often on a very small circle one wheel is 

 compelled to travel faster than the other; consequently 

 they cannot be both attached rigidly to the same shaft. 



FIG. 334 GEARS CONNECTING ENGINE WITH TRACTION WHEELS 



If one wheel were attached to the shaft and the other 

 were allowed to go free then one wheel would do all 

 of the traction work. This would not do, since the engine 

 would have only half of the tractive power and for road 

 work it is necessary that every pound possible of trac- 

 tive pull be developed. To arrange the drive wheels of 

 a traction engine so that both will pull when the engine 

 'is traveling in a straight line and also so they will travel 



