2?4 



AGRICULTURAL ENGINEERING 



fodder is fed directly into the cylinder. The third type of 

 machine has a large number of narrow, hook-shaped knives 

 arranged spirally around the main shaft, and may be desig- 

 nated as the spiral knife machine. These cut as well as split 

 the fodder as it is fed directly into the cylinder. 



Considering the relative merits of these various types of 

 machines, the radial knife certainly has the advantage in 

 simplicity. The fan blades are attached directly to the 

 main cutting wheel, and this single rotating part forms the 

 principal portion of the machine. All that is required in ad- 

 dition is the feeding mechanism. The knives of this machine 

 are more easily sharpened, as they are at least straight on 

 the flat side. As the knives are often supported their entire 

 length, they may be thinner, requiring less grinding in 

 sharpening. 



ITig. 175. Cutting heads of three types of ensilage cutters; 1 is the 

 radial knife, 2 the twisted knife, and 3 is the spiral knife. 



The twisted knife machine is capable of very rigid con- 

 struction and is safe against an explosion from overspeed. 

 The spiral knives may be sharpened by filing without being 

 removed from the machine. Most machines can be 



