THE HYDRAULIC PRESS 



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The opening of the auxiliary valve thus leads indirectly to the opening 

 of the corresponding main valve. During the idle part of the down 

 stroke both auxiliary valves are closed, a partial vacuum is produced 



above the exhaust valve, which opens, and water is drawn from the 

 exhaust into the cylinder. When pressure is required, a quarter-turn of 

 the operating lever raises the valve V\ and thus the pressure valve, and 

 admits pressure water through the passage PI to the cylinder. On the 

 working stroke being completed, a half turn of the lever closes V l and 



