CORN MACHINERY 223 



teeth called splitters may be attached to split the ends of 

 the stalk before they are cut off. 



The second type of cutter head is the one which carries 

 a spiral knife. The cutting edge is always the same dis- 

 tance from the shaft (Fig. 169). The knife may be pro- 

 vided with saw teeth for handling dry feed to better 

 advantage. 



306. The feeding table is provided on the larger power 

 machines with an end- 

 less apron to carry the 



fodder to the feed rolls. 

 The speed of the feed 

 rolls and the apron is 

 capable of adjustment FIG. 169 A SPIRAL KNIFE CUTTER HEAD 



for various rates of feed and coarseness of cutting. 



307. Elevators are of two general types : double-chain 

 conveyor or web-carrier elevator, and the pneumatic. 

 The carrier elevator is satisfactory except for very high 

 lifts. The long webs are a source of trouble. It is eco- 

 nomical to build silos high; hence the use of pneumatic 

 or wind elevators. It is necessary to keep the elevator 

 pipe almost perpendicular, or the silage will settle to one 

 side and not be carried up by the air blast. 



308.. Selection. All bearings, especially those con- 

 nected with the cutting knives and feed rollers, should 

 be very long. The shaft should be strong, and the gears 

 heavy enough to stand a variable load. It is well to have 

 the feed rollers so arranged that should more feed go in 

 one side than on the other, that side could expand, yet 

 grip the feed firmly. Since the cutter head should have 

 a capacity of from 600 to 1,000 revolutions a minute, the 

 frame should be made exceptionally strong and stiff. 

 Provision should be made so the bearings cannot wind, 

 as this causes much more friction and thus will require 



