THRESHING 71 



a strong draft produced by a rotating fan situated 

 below the grain board. This draft blows the chaffy 

 material to the back part of the machine into the 

 stacker. Some of the grains which have not been 

 entirely freed of the glumes (chaff) will not pass 

 through the sieve and are also too heavy to be 

 blown into the stacker. To avoid losing these, a 

 trough is provided which catches and discharges 

 them into a tailings elevator by which they are 

 carried to the front end of the machine and are 

 sent through a second time. The grain, rid of 

 impurities by sifting and fanning, is collected into 

 a trough and discharged into an elevator. This 

 elevator carries it to a weigher at the top of the 

 machine which weighs and registers, then dumps 

 it into wagons or bags. The stacker, which was 

 mentioned as the device which carries the straw 

 from the machine, may be a belt elevator. It is 

 more usually, however, a ' blower ' or wind 

 stacker, a tube through which the straw is blown 

 by a strong current of air produced by a fan at 

 the base. Where the blower is used, it can be so 

 swung about from time to time that the straw can 

 be built into fairly good stack? without manual 

 labor on the straw stack. Where the belt elevator 

 is used, two or more men are needed to take care 

 of the straw. The larger machines now use the 

 blower almost exclusively. 



The sizes and capacities of threshers vary in 



