THE CYLINDER, CONCAVES AND BEATER. 139 



girt to which they are fastened on wood separators or by 

 moving the girts to the upper holes on steel machines. There 

 is also provision in the girts for moving the beater back to 

 give more room between beater and cross-piece, but it is 

 very seldom necessary to move it. The speed of the beater 

 is four hundred revolutions per minute and as its bearings 

 are provided with hard oil cups, a little attention will keep 

 them in good running order. 



The Grates. A large percentage of the grain is separated 

 from the straw by the grates through which it is thrown with 

 all the force acquired from the cylinder. The grate under 

 the beater is adjustable and should usually be kept as high 

 as possible for the separation is better when it is high. It 

 should never be lowered unless absolutely necessary. 



The Check Board should usually be kept quite low to pre- 

 vent the grain from being thrown to the rear of the machine 

 on top of the straw, where it might be carried out of the 

 machine without being separated. In damp grain 'and es- 

 pecially damp rye or oats the check board should be raised 

 to allow the straw to pass freely through the machine, for if 

 left down, it will retard the straw too much, and may cause 

 the cylinder to wind. 



