Hydraulic device

Claim 1

IN AN OVERCENTER MOTOR-PUMP UNIT OF THE ROTARY CYLINDER BARREL, LONGITUDINALLY RECIPROCATING PISTON TYPE HAVING A HOUSING CONTAINING HIGH AND LOW PRESSURE PORTS, AND IN WHICH THE PISTONS ARE MOVED ON THEIR DISCHARGE STROKES BY A CAM PLATE WHICH IS ANGULARLY SHIFTABLE BETWEEN FIRST AND SECOND MAXIMUM DISPLACEMENT POSITIONS ON OPPOSITE SIDES OF A ZERO DISPLACEMENT POSITION, THE IMPROVEMENT WHICH COMPRISES (A) A FIRST PISTON MOTOR INCLUDING A WORKING CHAMBER AND FIRST AND SECOND RELATIVELY MOVABLE MEMBERS, ONE MEMBER BEING A PISTON AND THE OTHER BEING A CYLINDER, THE FIRST MEMBER BEING IN OPERATIVE ENGAGEMENT WITH THE CAM PLATE AND THE MOTOR BEING ARRANGED TO SHIFT THE CAM PLATE IN THE DIRECTION OF THE FIRST MAXIMUM DISPLACEMENT POSITION; (B) A PAIR OF OPPOSED SPRING SEATS, ONE CARRIED BY EACH OF SAID MEMBERS OF THE FIRST PISTON MOTOR; (C) A COIL COMPRESSION SPRING REACTING BETWEEN THE SPRING SEATS AND ACTING THROUGH THE FIRST MEMBER OF THE FIRST PISTON MOTOR TO URGE THE CAM PLATE IN THE DIRECTION OF THE FIRST MAXIMUM DISPLACEMENT POSITION; (D) A SECOND PISTON MOTOR INCLUDING A WORKING CHAMBER AND FIRST AND SECOND MEMBERS, ONE MEMBER BEING A PISTON AND THE OTHER BEING A CYLINDER, THE FIRST MEMBER BEING STATIONARY AND FIXED TO THE HOUSING AND THE SECOND BEING CONNECTED WITH THE SECOND MEMBER OF THE FIRST PISTON MOTOR AND MOVABLE BETWEEN FIRST AND SECOND POSITIONS IN A DIRECTION THAT CAUSES THE FIRST PISTON MOTOR TO SHIFT THE CAM PLATE IN THE DIRECTION OF THE FIRST MAXIMUM DISPLACEMENT POSITION;