TRACTION ENGINES 



451 



in a curve without slipping, a compensating gear is in- 

 serted in the chain of transmission. 



589. Compensating gears. Fig. 335 shows a simple, 

 very effective compensating gear. The large pinion A 

 carries the small pinions CCC. The shaft F is connected 

 to the flywheel on the opposite side of the engine by 

 means of a small pinion. The pinion G is connected to the 

 other main gear. The power is transmitted from the en- 

 gine shaft to the pinion A. As pinion A revolves in the di- 

 rection of the arrow, pinions CCC will be driven, and they 



in turn will propel the drive 

 wheels. But if the drive 

 wheel attached to pinion G 

 happens to travel faster than 

 that attached to shaft F the 

 pinion C will revolve and 

 still the pinion A will propel 

 the gearing. Often there are 

 some very severe jerks on 

 the transmission gearing of 

 an engine and some com- 

 panies are now inserting in 

 their compensating gears a 

 set of springs which take this jar off the gearing. 



590. Traction. Any traction engine has power enough 

 to propel itself over the road and through the fields pro- 

 vided the drive wheels do not slip. Consequently the 

 matter of the wheels adhering to the ground is an im- 

 portant part. Where the road surface is firm there is no 

 difficulty ; but in a soft field great trouble is experienced 

 due to the fact that the lugs of the drive wheels tear up 

 the earth and allow the drive wheels to move without 

 moving the engine. It is a common belief that the drive 

 wheel which has the sharpest lug is the one which will 



FIG. 335 COMPENSATING GEARS 



