Power brake booster control valve mechanism

Claim 1

IN A FORCE PRODUCING DEVICE, A FLUID PRESSURE OPERATED MOTOR INCLUDING A CASING HAVING A PRESSURE DIFFERENTIAL RESPONSIVE MOVABLE WALL OPERABLE THEREIN, A FOLLOW-UP CONTROL VALVE MECHANISM CARRIED BY SAID WALL HAVING ONE POSITION TO ESTABLISH EQUIVALENT PRESSURES ON OPPOSITE SIDES OF THE WALL TO RENDER THE SAME INACTIVE AND A SECOND POSITION TO ESTABLISH DIFFERENTIAL PRESSURES ON OPPOSITE SIDES OF THE WALL TO RENDER THE SAME ACTIVE TO EFFECT A FORCE APPLYING STROKE THEREBY; SAID CONTROL VALVE MECHANISM INCLUDING, A FIRST ANNULAR VALVE ELEMENT, A SECOND ANNUALAR VALVE ELEMENT ON A MEMBER MOVABLE RELATIVE TO SAID FIRST VALVE ELEMENT, AND A RESILIENT ANNULUS OF ROUNDED CROSSSECTION FORMING A VALVE SEAT MEMBER MOVABLE WITH RESPECT TO ONE OF THE VALVE ELEMENTS, AND THE OTHER OF THE VALVE ELEMENTS AND THE MEMBER ON WHICH THE OTHER VALVE ELEMENT IS CARRIED BEING MOVABLE WITH RESPECT TO SAID VALVE SEAT MEMBER, SAID VALVE SEAT MEMBER BEING ENGAGEABLE WITH BOTH SAID VALVE ELEMENTS FOR ANNULAR SEATING THEREON, AND SPRING MEANS URGING SAID SEAT MEMBER TOWARD SEATING ON THE RESPECTIVE VALVE ELEMENT ENGAGED THEREBY.