THRESHING WITH REGULARLY EQUIPPED SEPARATOR 183 



work the machine is doing, what changes in the adjustment 

 or arrangement of concaves or in the speed, will improve 

 the work. For example, if the wheat be thoroughly 

 knocked out of the heads and there be an excessive amount 

 of chaff and chopped straw, it would be well to see if the 

 kernels could still be threshed clean from the straw if the 

 concaves were lowered a notch or two, or perhaps one filled 

 concave replaced by a blank or else the speed lowered 

 slightly. If any of these changes were made, the work of 

 the machine as a whole would be improved, for separation 

 and cleaning are made easier by reducing the amount of 

 chopped straw. 



With certain conditions of the straw, in which the 

 heads are easily broken off, it may be best to use a cast con- 

 cave in place of the wrought grate, if the first concave 

 breaks off the heads and they fall through the grate blank 

 before the second concave can get action on them. If 

 whole heads are found passing over the conveyor try an 

 unfilled concave in place of the wrought blank. 



The adjustable-chaffer, chaffer-extension and shoe- 

 sieve can be best adjusted while the machine is running, 

 the operator noting how much chaff each is handling, how 

 the wheat is cleaned and the amount of tailing being re- 

 turned, as explained in Chapter IV. The adjustable shoe- 

 sieve should be placed at, or very near, the top, at the fan 

 end and in the fourth hole from the top at the rear end. 



When the separator is equipped with common sieves, 



