THRESHING MACHINERY 



219 



speeds. The two cylinders are necessary owing to the 

 fact that these crops can never be cured uniformly. When 

 the pods are dry the seeds are readily separated from the 

 pods, and if threshed violently the seeds will split. On the 

 other hand, when the pods are not dry the seeds cannot 

 be separated readily and are not inclined to split. Thus 

 in the special bean thresher the vines and pods are fed 

 through a cylinder run at a low speed, which threshes out 

 the dry pods. The threshed seeds are screened out, and 

 the remaining material passes to a cylinder run at a 

 higher speed to have the damp and greener pods 



FIG. 165 J SECTION OF A PEA AND BEAN THRESHER WITH TWO CYLINDERS 



threshed. The bean thresher is often provided with a re- 

 cleaner and clod crusher to remove the dirt. The size 

 of the bean and pea threshers is indicated by the width 

 of cylinder and the width of the separator or machine 

 proper. Machines are usually built in the 16 X 28-, 

 26 X 44-, and 36 X 44-inch sizes. The larger sizes have 

 a capacity up to 100 bushels of clean seed an hour. 



303. Clover hullers resemble threshing machines very 

 much, but differ in being provided with an additional 

 hulling cylinder. In passing the threshing cylinder the 

 heads are removed from the stems and the seed from the 

 heads to some extent. The heads are separated from the 



