HAYING MACHINERY 189 



of the team. Various devices or mechanisms are used to 

 obtain power for the compression. It is desired that the 

 motion be fast at the beginning of the stroke, while the 

 hay is loose, and slow while the hay is compressed during 

 the latter part of the stroke. The cam is the most com- 

 mon device to secure this; however, gear wheels with a 



FIG. 144 A HAY PRESS FOR ENGINE POWER AND EQUIPPED WITH A CON- 

 DENSER TO THRUST THE HAY INTO THE HOPPER 



cam shape are often used. The rebound aided by a spring 

 is usually depended upon to return the plunger for a new 

 stroke ; but a cam motion may be made use of to return 

 the plunger. It is to be noted that some machines use a 

 stiff pitman and push away from the power, while others 

 use a chain and rod and pull the pitman toward the power 

 or reverse the direction of travel of the plunger. A horse- 

 power machine has an average capacity of about 18 tons 

 a day. A cubic foot of hay before baling weighs 4 or 5 

 pounds when stored in the mow or stack. A baling press 

 increases its density to 16 or 30 pounds a cubic foot. 

 Specially designed presses for compressing hay for export 

 secure as high as 40 pounds of hay a cubic foot. 



265. Power presses make use of several variable-speed 

 devices and a flywheel to store energy for compression. 

 Power machines are often provided with a condenser to 



