THRESHING MACHINERY 213 



this manner. At the back of the chaffer is placed the 

 tailings auger, which catches the part heads and grains 

 with the outer hulls, to return them by way of the tail- 

 ings elevator to the cylinder to be rethreshed. Over the 

 tailings auger an adjustable conveyor extension is 

 usually placed to aid in stopping the unthreshed heads. 



293. The shoe. The shoe is the box in which the 

 sieves are mounted, and which has a tight, sloping bot- 

 tom to carry the threshed grain to the grain auger. The 

 shoe is always given a motion to shake the grain through 



FIG. l6l FAN, SHOE, AND CHAFFER 



it. If this motion be lengthwise with the machine, it is 

 said to have end shake; if across the machine, it is said 

 to have cross shake. The latter is used very little at 

 present. 



294. The sieves. The sieves consist of a wooden 

 frame covered with woven wire cloth or a perforated 

 sheet of metal. Adjustable sieves are constructed in 

 which the size of openings may be adjusted to suit the 

 work done. The openings in the sieve should be large 

 enough to permit the passage of the kernel downward; 



