Control valve for hydraulic lift truck

Claim 1

FOR USE IS A TRUCK OF THE CLASS DESCRIBED, A PRESSURE RELIEF VALVE FOR CONTROLLING FLUID PRESSURE THAT IS APPLIED BETWEEN A PUMP AND A LIFTING RAM, SAID VALVE COMPRISING A BODY HAVING A BORE IN COMMUNICATION WITH A SOURCE OF FLUID PRESSURE. A VALVE SEAT FORMED ABOUT SAID BORE ON THE VALVE BODY, A VALVE MOVABLE RELATIVELY TO SAID SEAT FOR DISCHARGING PRESSURE FROM THE BORE IN SAID VALVE BODY, A CONTROL MEMBER MOUNTED FOR MOVEMENT IN ALIGNED RELATION TO SAID VALVE AND VALVE SEAT, A SPRING HAVING ONE END ENGAGED WITH SAID CONTROL MEMBER AND AN OPPOSED END EXTENDING TOWARD THE VALVE, MEANS FOR APPLYING SAID OPPOSED END OF SAID SPRING TO THE VALVE AND ENGAGEABLE WITH THE CONTROL MEMBER TO LIMIT THE EXTENSION OF THE SPRING WHILE HOLDING SAID SPRING ASSEMBLED RELATIVELY TO THE CONTROL MEMBER, MOVABLE HOLDING MEANS FOR HOLDING SAID CONTROL MEMBER IN A POSITION IN WHICH THE PRESSURE OF THE SPRING PRESSES THE VALVE AGAINST ITS SEAT, SAID SPRING YIELDING TO EFFECT PREDETERMINED RELIEF OF THE FLUID PRESSURE, AND MEANS FOR MOVING SAID HOLDING MEANS FOR EFFECTING A MOVEMENT OF SAID CONTROL MEMBER AWAY FROM SAID POSITION, SAID SPRING BY ITS ASSEMBLY TO THE CONTROL MEMBER THEN MOVING BODILY WITH THE CONTROL MEMBER AND FREEING THE VALVE FROM THE YIELDING SPRING PRESSURE TO ALLOW A PROMPT DISCHARGE OF FLUID PRESSURE PAST SAID VALVE.