Two-stage air powered pump

Abstract

A two-stage air powered hydraulic pump has a portion of the air pressure that operates the pump diverted directly to the reservoir. The air pressure on the reservoir presses hydraulic fluid in the reservoir out of the reservoir, through the pumping chamber and to the load to quickly advance the load under low load conditions and to pre-charge the pumping chamber.

1 . In an air powered hydraulic pump of the type having an air pressure input port, a hydraulic pressure port and a reservoir of hydraulic fluid, the improvement wherein a portion of the pressurized air input to the pump is diverted to the reservoir so as to pressurize the fluid in the reservoir and press it out of the pump through the hydraulic pressure output port. 
   
   
       2 . The improvement of  claim 1 , wherein hydraulic fluid is pressed into a pumping chamber of the pump by air pressure that is diverted to the reservoir. 
   
   
       3 . The improvement of  claim 1 , wherein an air valve is provided to turn the pump on and off. 
   
   
       4 . The improvement of  claim 3 , wherein the air valve also turns off the air pressure to the reservoir when it is off. 
   
   
       5 . The improvement of  claim 1 , wherein a valve is provided to enable adjustment of the air pressure on the reservoir without affecting the air pressure supplied to the pump. 
   
   
       6 . The improvement of  claim 5 , wherein the valve can be operated to turn off the air pressure on the reservoir.