l62 SCIENCE OF SUCCESSFUL THRESHING 



special clover concaves are necessary. Information con- 

 cerning them is given elsewhere in this book. 



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

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

 arator, there are screws, which press against the concave 

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

 and 2O-bar wood machines have 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 straight- 

 ener, 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 cyl- 

 inder if necessary, until they are jarred loose and come 

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

 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 Concerning the Cylinder. When the separa- 

 tor is belted to an engine, one should make sure that the 

 engineer has closed the throttle, opened the cylinder cocks, 

 and (if the engine be a traction) that the reverse-lever 

 is in the center notch before changing concaves, fixing 

 teeth or otherwise handling the separator cylinder. 



