Patent ID: 8128386

Claim:
A variable displacement pump and pump control system therefor to pump a fluid at selected pump output flow rates in a range of pump output flow rates, the system comprising: a variable displacement pump having a rotor shaft with which to rotate a pump rotating member about an axis of rotation to force fluid that has entered a pump inlet to a pump outlet, and a fluid volume displacement selection controller to select a volume of fluid to be forced from the pump inlet to the pump outlet by the rotating member during a rotation thereof, a movable lead screw coupled to directly transmit force to the displacement selection controller so as to alter the position thereof as a result of selected motion of the movable lead screw, and a lead screw positioner for selectively moving, or preventing the moving of, the movable lead screw by extending and retracting the movable lead screw through a threaded opening, wherein the lead screw positioner comprises an electrically powered motor, and wherein the lead screw positioner extends and retracts the movable lead screw by rotating the movable lead screw.