CHAPTER IV. 



GRAIN CLEANING MEMBERS 



In separating the grain from the straw, a large 

 quantity of chaff and refuse passes out with the ker- 

 nels. This is disposed of by passing the uncleaned 

 grain over a series of sieves, through which a current 

 or blast of air is forced. The combination of sieves 

 and blast fan is called the cleaning mill or shoe, and 

 takes the place of the fanning blanket of the old 

 threshing floor or the fanning mill of recent years. 



There are three things to be considered in refer- 

 ence to the cleaning mill or shoe, on which its 

 successful working depends, namely, the sieves, the 

 blast, and the sieve motion. The sieves should be 

 adapted to the kind of grain to be threshed and as 

 few as will do the work should be used, a greater 

 number retarding the blast and catching straw and 

 sticks. The blast should be strong enough to flow 

 constantly through the sieves, even when the latter 

 are heavily loaded. The motion of the sieves should 

 be sufficient to insure movement of the chaff and 

 kernels on the sieve surface. 



THE SIEVES. 



The sieve comprises a frame, mainly of wood, and 

 a woven wire or sheet metal body. The best prac- 

 tice of to-day favors perforated or corrugated sheet 

 metal sieves, although the wire mesh is still used. 



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