SEEDING MACHINERY 



125 



each cell until the cam passes and the arm drops, closing 

 the valve. Thus the length of this cam determines the 

 length of time the valve is open, thereby controlling the 

 number of kernels in the hill. Several lengths of cams 

 are furnished with each planter. It is claimed in opposi- 

 tion to the claim set forth for the intermittent movement 

 that the cells are more apt to be filled, for they are in con- 

 tinuous motion and travel a greater distance under the 

 corn. 



171. The clutch. In the early planters the plate was 

 driven entirely by the check wire. With each button the plate 



Top View 



FIG. 92 THE SEED-SHAFT CLUTCH WHICH IS THROWN IN GEAR BY THE 



CHECK WIRE. THE POWER TO DRIVE THE SEED SHAFT THEN 



COMES FROM THE MAIN AXLE, NOT THE CHECK WIRE 



was moved just far enough to deposit one hill in the seed 

 tube. When the cumulative drop was developed, a means 

 had to be provided to rotate the plate long enough to 

 count out the hill. To arrange for this, the button was 



