Dual direction relief or sequence type valve

Claim 1

IN A VALVE OF THE TYPE DESCRIBED WHICH INCLUDES MEANS FORMING A VALVE BETWEEN A FIRST PORT AND A SECOND PORT, SAID VALVE MEANS INCLUDING A MOVABLE ELEMENT THE POSITION OF WHICH CONTROLS THE FLOW OF FLUID BETWEEN SAID PORTS, MEANS FORMING A CONTROL PRESSURE CHAMBER THE PRESSURE IN WHICH ACTS TO URGE SAID MOVABLE ELEMENT IN ONE DIRECTION, MEANS PRESENTING A SURFACE SUBJECTED TO FLUID PRESSURE AT SAID FIRST PORT FOR URGING SAID MOVABLE ELEMENT IN THE OPPOSITE DIRECTION, ORIFICE MEANS THROUGH WHICH FLUID MUST FLOW TO ENTER SAID CONTROL CHAMBER, AND PILOT VALVE MEANS FOR CONTROLLING THE MAXIMUM PRESSURE IN SAID CONTROL CHAMBER, THE IMPROVEMENT WHICH MAKES THE VALVE RESPONSIVE TO THE HIGHER OF THE PRESSURES IN SAID FIRST AND SECOND PORTS WHICH COMPRISES A MOVABLE DIFFERENTIAL PRESSURE OPERATED PISTON MEANS HAVING OPPOSITE SURFACES DISPOSED TO BE ACTED UPON RESPECTIVELY BY THE FLUID PRESSURES AT SAID FIRST PORT AND AT SAID SECOND PORT AND ARRANGED TO COOPERATE WITH SAID SURFACE PRESENTING MEANS FOR URGING SAID MOVABLE ELEMENT IN SAID OPPOSITE DIRECTION WHEN THE PRESSURE AT SAID SECOND PORT IS GREATER THAN THE PRESSURE AT SAID FIRST PORT, AND VALVE MEANS OPERATED BY SAID MOVABLE PISTON MEANS FOR CONNECTING SAID ORIFICE MEANS WITH WHICHEVER OF SAID PORTS CONTAINS THE HIGHER PRESSURE WHILE ISOLATING SAID ORIFICE MEANS FROM THAT PORT WHICH CONTAINS THE LOWER PRESSURE.