138 SCIENCE OF SUCCESSFUL THRESHING. 



Adjustment of Concaves. In the left side of the "iron- 

 sides," or cylinder side castings, of the wood 12 bar sep- 

 arator, there are thumbscrews, which press against the con- 

 cave circle and take up the end play of the concaves. The 

 steel and 20 bar wood machines have set screws in both 

 ironsides. When it is desired to change the concaves, raise 

 them up and drop them down a few times to jar out the 

 dust and dirt which has become lodged between concave 

 circles and ironsides, wedging them tight. With concaves 

 in their lowest position, place a stick of wood, the tooth 

 straightener, or anything else that may be handy, between 

 concave and cylinder teeth and raise the concaves so that 

 the teeth cannot pass. Then roll the cylinder backward, 

 striking the concaves several times with the momentum of 

 the cylinder if necessary, until they are jarred loose and come 

 up with the cylinder, as it is rolled backward by hand. The 

 thumb-screws mentioned above may be loosened if necessary, 

 but if they be, it should be done on one side only so as not 

 to disturb the adjustment. 



Caution. When the separator is belted to an engine one 

 should make sure that the engineer has closed the throttle 

 and opened the cylinder cocks before changing concaves, 

 fixing teeth or otherwise handling the separator cylinder. 



The Beater. In threshing very heavy, tough grain, if the 

 straw be inclined to wrap the beater or if it tends to follow 

 the cylinder around too far, the beater may be raised by tak- 

 ing out the blocks from between the beater boxes and the 



