CHAPTER II 

 THE CYLINDER, CONCAVES AND BEATER 



IT is the function of the cylinder and concaves to loosen 

 the kernels of grain from the straw on which they 

 grew. The ends of the cylinder teeth travel about a 

 mile a minute so that the grain in going through meets 

 the concave teeth with considerable force. The concave 

 teeth engage with the cylinder teeth in such a way that 

 the grain heads cannot pass through without being broken 

 and the kernels knocked out although the straw is in contact 

 with the cylinder but a fraction of a second. If the teeth 

 be in good condition and a sufficient number of rows of 

 concave teeth be used to suit the work, practically all of 

 the grain will be knocked out. 



Cylinder Teeth. When the cylinder is new or newly 

 refilled, care should be taken to keep the teeth tight until 

 they become fitted to their holes and firmly seated. The 

 cylinder should be gone over two or three times during the 

 first week, and each tooth driven in hard with a heavy 

 hammer and the nuts tightened. Afterwards they should 

 be gone over often enough to be sure that they are tight 

 and will not bother while threshing. A light tap with the 

 hammer on the side of the tooth will produce a sound which 

 will easily reveal whether or not it is tight At the factory, 



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