744 



HYDRAULICS AND ITS APPLICATIONS 



Thus if a = 2 feet per second per second, while F = 10 per cent, of 

 the total force on ram, we have 



4,480 



area of ram 



750 



4,480 

 = 1*17 X 7r() - = = 7 square inches. 



In practice it is usual to make allowance for friction and acceleration 



From LOW Pressure \ 



To Lif 't Cylinder 



From High Pressure Supply 

 'D 



FIG. 361. Balance Cylinder for Hydraulic Lift. 



by making calculations for a load about 25 per cent, in excess of the 

 nominal. 



If the area of the ram be increased, the working pressure must be 

 reduced to suit, and for this purpose some form of pressure reducer in 

 effect a reversed intensifier is used. Also, since the weight of ram and 

 cage forms a large proportion of the whole load to be lifted, this must be 

 balanced for efficient working. 



