SCIENCE OF THRESHING. 145 



is very severe. The ordinary traction engine weighs 

 from four to twelve tons and to set this great weight 

 in motion suddenly puts an enormous load on the 

 driving mechanism. 



The engine should be started slowly. The fric- 

 tion clutch may be then thrown in gradually until the 

 traction gearing is set in motion when the clutch may 

 be sent home and the throttle opened sufficiently 

 to give full speed to the engine. 



The friction shoes of the clutch should be just tight 

 enough to insure proper driving of the engine without 

 slipping; if too tight, there is undue strain and wear 

 on the parts which come in contact with the wheel. 



SETTING THE ENGINE. 



When setting the engine in line with the separator, 

 the flywheel of the engine and drive pulley of the 

 separator should be placed in line and near enough to 

 each other so that the drive belt, when placed thereon, 

 is not too loose. The engine is then started and the 

 friction clutch is thrown in for a moment, causing the 

 engine to travel backwards and tighten the belt 

 sufficiently to drive the separator. The engine is then 

 blocked to prevent it from moving ahead when the 

 clutch is released, as it would otherwise do, owing 

 to the tension of the drive belt. 



GEAR LOCK. 



If a gear lock is on the engine, it should be thrown 

 in before the engine is started backwards. 



The engine should be set nearly even or level for 

 threshing or other stationary work. The rear end 



