Fluid system and relief valve assembly therefor

Claim 1

IN COMBINATION, A DIRECTIONAL CONTROL VALVE ASSEMBLY HAVING AN INLET PORT FOR FLUID COMMUNICATION WITH A PUMP AND PROVIDING TWO PRESSURE CIRCUITS FROM SAID INLET PORT FOR FLUID MOTOR ACTUATION; VALVE MEANS IN SAID ASSEMBLY SELECTING EITHER ONE OF SAID CIRCUITS FOR MOTOR ACTUATION; A RELIEF VALVE HAVING A RELIEF PORT IN FLUID COMMUNICATION WITH SAID INLET PORT AND A CONTROL PORT IN FLUID COMMUNICATION WITH BUT ONE PRESSURE CIRCUIT, SAID RELIEF VALVE COMPRISING A MOVABLE RELIEF VALVE MEMBER THEREIN, SPRING MEANS BIASING SAID RELIEF VALVE MEMBER TO A POSITION CLOSING SAID RELIEF PORT, AND A FLUID PRESSURE ACTUATED MEANS BEARING ON SAID SPRING MEANS IN A DIRECTION FOR YIELDABLY HOLDING SAID RELIEF VALVE MEMBER IN A POSITION CLOSING SAID RELIEF PORT, SAID FLUID PRESSURE ACTUATED MEANS BEING EXPOSED TO FLUID UNDER PRESSURE IN SAID CONTROL PORT AND MOVABLE THEREBY TO DECREASE THE SPRING BIAS ON SAID RELIEF VALVE MEMBER WHEREBY THE LATTER OPENS SAID RELIEF PORT TO SAID INLET PORT AT A LOWER FLUID PRESSURE WHEN SAID ONE CIRCUIT IS SELECTED FOR MOTOR ACTUATION THAN WHEN THE OTHER CIRCUIT IS SELECTED FOR MOTOR ACTUATION.