52 SCIENCE OF THRESHING. 



its working when the frame does a part of the 

 moving, which the mechanisms complete. 



There is another reason why the separator should 

 be made to stand still. When the engine is running, 

 one part of the drive belt is drawn tight while the 

 other is slack. The harder the engine is being driven, 

 the tighter will the belt be drawn; if the separator 

 is rocking on its trucks to and from the engine it will 

 take up some of the slack of the belt as it sways 

 toward the engine and when moving backward away 

 from the engine the belt will either have to stretch 

 or slip upon the pulley, as it cannot change the speed 

 of the cylinder. As the slack has already been taken 

 up it is very likely to slip, an action which is very 

 hard on the pulley lagging, and on the belt, and 

 which wastes a great deal of power. This slipping 

 and straining of the belt is greatly augmented if the 

 engine also moves upon its trucks, as the vibrations 

 of the two machines will not be the same, and when 

 one is rocking in one direction, and the other in the 

 opposite direction, there will be double the pull on 

 the belt. If a horse power is used, there is the same 

 need for the separator to stand still, as the strain 

 from the oscillations and vibrations are very severe 

 on the tumbling rods. 



If the separator fails to take the grain out of the 

 straw properly, it is usually because of one or more 

 of the following reasons, viz. : 



The separator is not standing still on its trucks; 

 it is not running at the proper speed; the cylinder 

 fails to thresh all the kernels out of the heads; the 



