Pressure control valve for hydraulic fastener applying tools

Claim 1

IN A FLUID MOTOR WHICH INCLUDES A BODY DEFINING A BORE, A PISTON MOUNTED FOR RECIPROCATION IN SAID BORE MEANS IN SAID BODY DEFINING A FLUID INLET PASSAGEWAY COMMUNICATING WITH SAID BORE FOR DELIVERING FLUID HAVING A PRESELECTED PRESSURE TO THE BORE FOR DRIVING THE PISTON IN A FIRST DIRECTION, A VALVE HOUSING CONNECTED TO SAID BODY AND HAVING A FIRST FLUID PASSAGE THEREIN CONNECTED TO SAID INLET PASSAGEWAY AND A SECOND FLUID RETURN PASSAGE, VALVE MEANS MOUNTED IN SAID VALVE HOUSING AND SELECTIVELY OPERABLE IN ONE POSITION TO ESTABLISH A FLUID PATH FROM SAID FIRST PASSAGE TO SAID RETURN PASSAGE FOR DIVERTING A PORTION OF THE FLUID FROM SAID INLET PASSAGE FOR THEREBY CONTROLLING SAID PRESELECTED PRESSURE OF FLUID ENTERING SAID INLET PASSAGEWAY FROM SAID FIRST PASSAGE FOR DRIVING THE PISTON IN SAID FIRST DIRECTION UNDER A DIFFERENT FLUID PRESSURE, AND ADJUSTABLE RELIEF VALVE MEANS IN SAID FLUID PATH SELECTIVELY ADJUSTABLE FOR DIVERTING SELECTED PORTIONS OF THE FLUID FROM SAID FIRST PASSAGE, SAID RELIEF VALVE MEANS INCLUDING A VALVE MEMBER ACTUABLE RESPONSIVELY TO THE FLUID PRESSURE IN SAID FIRST PASSAGE FOR DIVERTING SELECTED PORTIONS OF THE FLUID FROM SAID FIRST PASSAGE AND ADJUSTABLE BIASING MEANS SELECTIVELY MOVABLE TO A PLURALITY OF POSITIONS FOR SELECTIVELY VARIABLY BIASING SAID VALVE MEMBER AND FOR SELECTIVELY VARYING THE PRESSURE AT WHICH SAID VALVE MEMBER IS ACTUABLE.