Bypass valve with limited reset

Claim 1

A PRESSURE REGULATING SYSTEM CONTROLLING THE PRESSURE DROP PA-PB ACROSS AN ORIFICE LOCATED IN A CONDUIT OF A HYDRAULIC CIRCUIT WHEREIN PA IS THE PRESSURE IN THE CONDUIT UPSTREAM OF THE ORIFICE AND PB IS THE PRESSURE IN THE CONDUIT DOWNSTREAM OF THE ORIFICE, SAID PRESSURE REGULATING SYSTEM COMPRISING A BYPASS VALVE ASSEMBLY INCLUDING A MOVABLE BYPASS VALVE ADAPTED TO BE CONNECTED AT ONE SIDE TO THE PRESSURE PA IN THE CONDUIT, A HOUSING, A MOVABLE WALL FORMING A RESETTABLE SPRING SEAT SPANNING THE INTERIOR OF SAID HOUSING AND DIVIDING SAID HOUSING INTO A PAIR OF COMPARTMENTS, A SPRING IN ONE OF SAID COMPARTMENTS ENGAGEABLE WITH SAID SPRING SEAT AND THE OTHER SIDE OF SAID BYPASS VALVE AND ACTING IN A DIRECTION TO CLOSE SAID VALVE, A SERVO VALVE ASSEMBLY INCLUDING A HOUSING HAVING A MOVABLE WALL THEREIN WHICH DIVIDES SAID HOUSING INTO A PAIR OF CHAMBERS, A VALVE PORT IN SAID LASTMENTIONED HOUSING IN FLUID COMMUNICATION WITH ONE OF SAID CHAMBERS, FIRST PASSAGE MEANS ADAPTED TO CONNECT THE PRESSURE PB TO THE OTHER OF SAID CHAMBERS AND ALSO TO SAID ONE COMPARTMENT TENDING TO CAUSE MOVEMENT OF SAID SPRING SEAT IN A DIRECTION TO DECREASE THE EFFECTIVENESS OF SAID SPRING, SECOND PASSAGE MEANS ADAPTED TO CONNECT THE PRESSURE PA TO SAID ONE CHAMBER, THIRD PASSAGE MEANS CONNECTED TO SAID VALVE PORT AND HAVING A FIXED RESTRIC-