Variable displacement check valve pump

Claim 1

IN A PUMP HAVING A HOUSING PROVIDED WITH AN INLET AND AN OUTLET, MEANS DEFINING A PLURALITY OF CIRCUMFERENTIALLY SPACED CYLINDRICAL BORES IN SAID HOUSING, A PISTON MOUNTED FOR RECIPROCATION IN EACH OF SAID BORES, A ROTARY DRIVE SHAFT, A CAM MOUNTED ON SAID DRIVE SHAFT FOR RECIPROCATING SAID PISTONS, ACTUATOR MEANS RESPONSIVE TO OUTPUT PRESSURE FOR ROTATING SAID CAM TO A POSITION IN WHICH THE EFFECTIVE STROKE OF SAID PISTONS IS VARIED AS REQUIRED, A THRUST MEMBER CARRIED BY SAID DRIVE SHAFT AND BEING ANGULARLY DISPOSED WITH RESPECT TO THE AXIS OF SAID DRIVE SHAFT, SAID CAM MOUNTED FOR ROTATION WITH SAID THRUST MEMBER, AND INCLUDING A SURFACE OPERATIVELY ASSOCIATED WITH SAID PISTONS, SAID CAM BEING OF WEDGE CROSS SECTION AND BEING RELATIVELY ROTATABLE WITH RESPECT TO SAID THRUST MEMBER SO AS TO PRESENT SAID SURFACE ANGULARLY DISPOSED WITH RESPECT TO SAID DRIVE SHAFT OR PERPENDICULAR TO SAID DRIVE SHAFT, AND SAID ACTUATOR MEANS EFFECTING ROTATION OF SAID CAM WITH RESPECT TO SAID DRIVE SHAFT IN RESPONSE TO OUTPUT PRESSURE FROM SAID PUMP.