Depressurizing and blocking valve means for variable displacement pump

Claim 1

DEPRESSURIZING AND BLOCKING VALVE MEANS FOR A VARIABLE DISPLACEMENT PUMP OF THE TYPE HAVING A FLUID MOTOR FOR CHANGING THE DISPLACEMENT THEREOF, COMPRISING, A BODY HAVING A PRESSURE INLET AND A PRESSURE OUTLET, A PISTON COOPERABLE WITH A VALVE SEAT BETWEEN SAID INLET AND OUTLET TO FORM A VALVE, MEANS FOR APPLYING PRESSURE FLUID FROM SAID INLET TO SAID PISTON TO MOVE SAID PISTON TOWARD SAID SEAT AND CLOSE SAID VALVE, SAID MEANS INCLUDING A SELECTIVELY OPERABLE CONTROL VALVE AND A FLOW RESTRICTING PASSAGE DEFINED BY AND BETWEEN SAID PISTON AND BODY WHEN SIAD PISTON APPROACHES SAID SEAT, FIRST PASSAGE MEANS FOR APPLYING PRESSURE FLUID FROM SIAD INLET TO SAID FLUID MOTOR INCLUDING A PORTION WITHIN SAID PISTON, A SPOOL MOVABLE IN THE PORTION OF SAID FIRST PASSAGE MEANS WITHIN SIAD PISTON AND PRESENTING A FIRST TRANSVERSE SURFACE FORMING A FIRST VALVE WITH SAID PISTON IN SAID PASSAGE MEANS FOR CONTROLLING THE APPLICATION OF FLUID THERETHROUGH TO SAID MOTOR, SAID FIRST TRANSVERSE SURFACE BEING ACTED UPON AT ALL TIMES BY PRESSURE FLUID IN SAID PASSAGE MEANS FROM SAID INLET, SECOND PASSAGE MEANS FOR RELEASING FLUID FROM SAID MOTOR INCLUDING A PORTION WITHIN SAID PISTON, SAID SPOOL ALSO PRESENTING A SECOND TRANSVERSE SURFACE FORMING A SECOND VALVE WITH SAID PISTON IN SAID SECOND PASSAGE MEANS FOR CONTROLLING THE RELEASE OF FLUID THERETHROUGH FROM SAID MOTOR, A SPRING HAVING ONE END FIXED WITH RESPECT TO SAID BODY AND URGING SAID SPOOL IN A DIRECTION AGAINST THE FORCE OF SAID PRESSURE FLUID ON SAID FIRST TRANSVERSE SURFACE AND TENDING TO CLOSE SAID FIRST VALVE AND OPEN SAID SECOND VALVE, THE FORCE APPLIED BY SAID SPRING TO SAID SPOOL BEING INDEPENDENT OF THE POSTION OF SAID PISTON BUT THE PRESSURE REQUIRED TO OPEN SAID FIRST VALVE DIMINISHING AS SAID PISTON APPROACHES SAID SEAT, AND MEANS FOR ADJUSTING THE FORCE OF SAID SPRING.