Dual pressure relief valve with shock damping

Claim 1

A DUAL PRESSURE RELIEF VALVE HAVING PRESSURE MODULATION FOR USE IN HYDRAULIC CIRCUITS WITH DUAL RELIEF PRESSURE REQUIREMENTS COMPRISING: A VALVE BODY HAVING A PORT THEREIN WHICH DRAINS TO RESERVOIR, SAID PORT BEING IN FLUID COMMUNICATION WITH A SOURCE OF PRESSURE FLUID; A DUMP SPOOL RECIPROCALLY MOUNTED IN A BALANCE CHAMBER IN SAID VALVE BODY AND OPERABLE TO CLOSE SUCH PORT TO PREVENT FLUID FLOW THERETHROUGH FROM SAID SOURCE OF PRESSURE FLUID TO RESERVOIR, SAID DUMP SPOOL HAVING AN ORIFICE THERETHROUGH WHEREBY PRESSURE FLUID MAY ENTER SUCH BALANCE CHAMBER TO COUNTERBALANCE FLUID PRESSURES ON SAID DUMP SPOOL FROM SAID SOURCE OF PRESSURE FLUID; A BIASING MEANS LOCATED IN SUCH BALANCE CHAMBER OPERABLE TO DIRECTIONALLY URGE SAID DUMP SPOOL TO CLOSE SUCH PORT; A DRAIN TO RESERVOIR LOCATED IN SUCH BALANCE CHAMBER; A SPRING BIASED POPPET MEANS CLOSING SAID DRAIN UNTIL PRESSURE IN SUCH BALANCE CHAMBER EXCEEDS THE BIAS; A PRESSURE RESPONSIVE MEMBER IN CONTACT WITH THE SPRING BIAS OPERABLE TO INCREASE SUCH BIAS WHEN SUBJECT TO PRESSURE FLUID; A PASSAGE FROM SUCH BALANCE CHAMBER TO SAID PRESSURE RESPONSIVE MEMBER WHEREBY PRESSURES IN SUCH BALANCE CHAMBER ARE REFLECTED AS SPRING BIAS ON SAID SPRING BIASED POPPET MEANS; AND SHUTTLE VALVE MEANS LOCATED IN SAID VALVE BODY OPERABLE TO CLOSE OFF SAID PASSAGE AND DUMP FLUID PRESSURE REFLECTED TO SAID PRESSURE RESPONSIVE MEMBER THROUGH SAID PASSAGE TO RESERVOIR CAUSING SAID RELIEF PRESSURE OF THE VALVE TO BE REDUCED.