72 



APPLIED SCIENCE 



Therefore, a pound pressure on the piston of the small cylinder 

 gives a total pressure of 100 Ibs. on the large cylinder. While the 



machine develops a cer- 

 tain amount of friction 

 at the stuffing box, 

 pins, etc., of the pump 

 or smaller cylinder, the 

 loss is probably only 

 5%. Therefore, as a 

 general rule, 95% of the 

 pressure applied to the 

 smaller cylinder is given 

 to or transmitted to the 

 water in the pump. 

 Figure 43 illustrates a 

 hydraulic press designed 

 to show a pressure up to 

 300 Ibs. to the square 



inch. The handle of 

 FIG. 43.-Hydraulic Press. the pump which com . 



presses the water in the small cylinder is seen on the left. 



71. Uses of Hydraulic Machinery. For the majority of 

 operations requiring very great force applied through a 

 comparatively short stroke, as in riveting, punching, shear- 

 ing, lifting, forging, flanging, and many other similar opera- 

 tions, there is no other machinery so efficient as hydraulic; 

 first, because there is absolutely no motion or power con- 

 sumed except in the act, and at the moment of performing 

 the desired operation at all other times everything is at 

 rest; secondly, because the water is carried or transmitted 

 in a small pipe from its reservoir or tank to the machine. 

 Under proper conditions, this transmission can be accom- 

 plished with an efficiency far surpassing that of the line-shaft, 

 electric wire, or air tube. All the energy which a steam pump 



