Patent ID: 8341955

Claim:
A hydraulic pumping system for distribution of process fluids: a process fluid pump for receiving a process fluid and pumping said process fluid from a pump outlet for distribution of said process fluid, said fluid pump discharging said process fluid from said pump outlet at an outlet pressure; a hydraulic motor which is drivingly connected to said fluid pump and receives a pressurized hydraulic system fluid to drive said fluid pump; a main pump having a pump output wherein said system fluid is discharged from said main pump at a system pressure defined by operation of said main pump, said main pump supplying said system fluid to said hydraulic motor, said main pump being a variable displacement hydraulic pump with said pump output being variable to vary said system pressure wherein changes to said system pressure effect corresponding changes to said outlet pressure of said process fluid, said main pump including a mechanical adjustment device to vary said system pressure by varying said pump output of said main pump; and a control system for adjusting said main pump comprising a hydraulic control actuator operatively connected to said mechanical adjustment device to vary said pump output, said control system including a charge pump which supplies a hydraulic charge fluid at a charge pressure to said control actuator, said control system further including, a pressure controller which receives said system fluid at said system pressure and includes a pressure adjustment device which is variable to set a maximum system pressure and which supplies hydraulic fluid at a control pressure to a first inlet of said control actuator wherein said control pressure corresponds to and varies with a maximum system pressure, said control actuator receiving said charge pressure and said control pressure in balancing relation to selectively adjust said mechanical adjustment device of said main pump to vary said system pressure from said pump output in correspondence to said control pressure and maintain said system pressure at said maximum system pressure.