Patent ID: 8459019

Claim:
A two-stage, high-pressure, pumping system comprising: a low-pressure pump having an output configured to deliver a hydraulic fluid under a low-pressure at a high-volume to drive a tool associated with the two-stage, high-pressure, pumping system under low load conditions; a high-pressure pump having an output configured to deliver the hydraulic fluid under a high-pressure at a low-volume to drive the tool under high load conditions; a pilot-operated device configured to selectively drive the tool from at least one of the output of the low-pressure pump and the output of the high-pressure pump, the pilot-operated device having at least one pilot port that is pressurized by a pilot pressure to actuate the pilot-operated device; and wherein the pilot pressure to actuate the pilot-operated device is provided only by the output of the low-pressure pump to control selectively driving the tool from one of the output of the low-pressure pump and the output of the high-pressure pump.