Dual control valve for vehicle brake systems

Claim 1

A DUAL CONTROL VALVE FOR A VEHICLE BRAKING SYSTEM THAT COMPRISES AN ACTUATOR ADAPTED TO BE SELECTIVELY CONTROLLED BY THE OPERATOR AND AT LEAST TWO INDEPENDENT SETS OF WHEEL BRAKES, COMPRISING A HOUSING HAVING TOW SEPARATE INLETS ADAPTED TO BE CONNECTED TO INDEPENDENT SOURCES OF FLUID P RESSURE, AND TWO SEPARATE OUTLETS ADAPTED TO BE CONNECTED TO THE INDIVIDUAL WHEEL BRAKE SETS, A PRIMARY PISTON SLIDABLY MOUNTED IN SAID HOUSING, A SECONDARY PISTON ASSEMBLY SLIDABLY MOUNTED IN SAID HOUSING COAXIALLY WITHE THE PRIMARY PISTON, MEANS PROVIDING A FIRST PASSAGE FROM ONE OF SAID INLETS THROUGH SAID SECONDARY PRISTON ASSEMBLY TO ONE SAID INLETS, A FIRST TUBULAR VALVE ELEMENT SLIDABLY MOUNTED ON SAID SECONDARY PISTON ASSEMBLY AND NORMALLY CLOSING SAID FIRST PASSAGE, MEANS PROVIDING A SECOND PASSAGE IN SAID FIRST PASSAGE, MEANS PROVIDING A TO THE OTHER OF SAID OUTLETS, A SECOND TUBULAR VALVE ELEMENT SLIDABLY MOUNTED IN SAID HOUSING AND SEATED FOR NORNALLY CLOSING SAID SECOND PASSAGE, MEANS PROVIDING AN OPERATIVE CONNECTION BETWEEN SAID ACTUATOR AND SAID PRIMARY PISTON WHEREBY WHEN THE OPERATOR SHIFTS SAID ACTUACTOR THE PRIMARY PISTON IS DISPLACED TO ENGAGE AND MOVE SAID FIRST VALVE ELEMENT TO OPEN SAID FIRST PASSAGE, MEANS RESPONSIVE TO SAID DIPLACEMENT OF THE PRIMARY PISTON FOR DISPLACING SAID SECONDARY PISTON ASSEMBLY TO ENGAGE AND MOVE SAID SECOND VALVE ELEMENT TO OPEN SAID SECOND PASSAGE, SAID SECONDARY PISTON ASSEMBLY COMPRISING TWO AXIALLY SEPARATE STRUCTURALLY DISTINCT COMPONENTS WITH SAID FIRST PASSAGE BEING FORMED THROUGH THAT ONE OF SAID COMPONENTS WHICH CARRIES SAID FIRST VALVE ELEMENT, AND THE OTHER OF SAID COMPONENTS BEING ADAPTED TO ENGAGE AND MOVE SAID SECOND VALVE ELEMENT, SURFACE MEANS IN SAID HOUSING, SAID SECONDARY PISTON ASSEMBLY AND AND SECOND VALVE ELEMENT DEFINING AN EXHAUST PASSAGE EXTENDING THROUGH SAID SECONDARY PISTON ASSEMBLY AND BOTHT OF SAID TUBULAR VALVE ELEMENTS, MEANS IN SAID HOUSING DEFINING AN EXHAUST PORT AT ONE END OF SAID EXHAUST PASSAGE FOR DISCHARGING FLUID FROM SAID EXHAUST PASSAGE, SAID EXHAUST PASSAGE BEING NORMALLY IN FLUID COMMUNICATION WITH SAID OUTLETS WHEN SAID VALVE ELEMENTS ARE IN PASSAGE CLOSED POSITION, SAID PRIMARY PISTON COOPERATING WITH SAID FIRST VALVE ELEMENT TO CLOSE COMMUNICATION BETWEEN SAID FIRST OUTLET AND SAID EXHAUST PASSAGE WHEN SAID FIRST PASSAGE IS OPENED TO ADMIT FLUID PRESSURE TO SAID FIRST OUTLET, AND SAID SECONDARY PISTON ASSEMBLY COOPERATING WITH SAID SECOND VALVE ELEMENT TO CLOSE COMMUNICATION BETWEEN SAID SECOND OUTLET AND SAID EXHAUST PASSAGE WHEN SAID SECOND PASSAGE IS OPENED TO ADMIT FLUID PRESSURE TO SAID SECOND OUTLET.