Control valves for air braking systems

Claim 1

A FLUID CONTROL VALVE FOR FLUID PRESSURE ACTUATED VEHICLE BRAKING SYSTEMS INCORPORATING AT LEAST ONE BRAKE CYLINDER, A SUPPLY SOURCE OF FLUID AT CONSTANT PRESSURE, A CONTROL FLUID PRESSURE SOURCE AND BRAKE APPLYING MEANS CONTROLLING CONTROL FLUID PRESSURE COMPRISING A VALVE BODY IN WHICH IS FORMED AN INLET PASSAGE FOR CONNECTION TO SAID FLUID PRESSURE SOURCE, AN OUTLET PASSAGE FOR CONNECTION TO SAID BRAKE CYLINDER, A VALVE SEATING IN THE VALVE, BODY BETWEEN SAID INLET PASSAGE AND SAID OUTLET PASSAGE, A PISTON LOCATED IN A CHAMBER IN SAID VALVE BODY, AN EXHAUST PASSAGE IN SAID VALVE BODY CONNECTING SAID CHAMBER TO ATMOSPHERE, A VALVE MEMBER ADAPTED TO COOPERATE WITH SAID VALVE SEATING TO CONTROL COMMUNICATION BETWEEN SAID INLET PASSAGE AND SAID OUTLET PASSAGE, A FIRST DIAPHRAGM OF FIXED AREA CONNECTED BETWEEN SAID PISTON AND SAID VALVE BODY AND SUBJECTED ON ONE SIDE TO PRESSURE IN SAID OUTLET PASSAGE AND ON AN OPPOSITE SIDE TO PRESSURE IN SAID CHAMBER, A COTROL MEMBER IN SAID CHAMBER ADAPTED TO BE MOVABLE INTO AN OPERATING POSITION DICTATED BY VEHICLE LOADING, A SECOND DIAPHRAGM OF VARIABLE AREA CONNECTED AT ITS INNER AND OUTER EDGES BETWEEN THE LOWER END OF THE PISTON AND SAID CONTROL MEMBER, THE EFFECTIVE AREA OF SAID SECOND DIAPHRAGM BEING VARIABLE IN ACCORDANCE WITH THE POSITION OF THE CONTROL MEMBER, THE SECOND DIAPHRAGM AND THE CONTROL MEMBER DEFINING BETWEEN THEMSELVES A COMPARTMENT SUBJECTED TO SAID COMTROL FLUID PRESSURE WHICH IS CONTROLLED BY SAID BRAKE APPLYING MEANS, A STEM ON SAID PISTON CO-OPERATING WITH SAID VALVE MEMBER CONTROLLING COMMUNICATION BETWEEN SAID INLET PASSAGE AND SAID OUTLET PASSAGE, A FIRST DIACONTROL FLUID PRESSURE BEING SUPPLIED TO SAID COMPARTMENT SAID VALVE MEMBER IS MOVED AWAY FROM SAID VALVE SEATING TO PROVIDE COMMUNICATION BETWEEN SAID INLET PASSAGE AND SAID OUTLET PASSAGE, THE MOVEMENT OF THE VALVE MEMBER BEING CONTROLLED IN ACCORDANCE WITH DIFFERENTIAL PRESSURE BETWEEN THE CONTROL FLUID PRESSURE AND OUTLET PRESSURE WHICH SAID OUTLET PRESSURE IS AT ALL TIMES PROPORTIONAL TO THE LOADING ON THE VEHICLE, AND A FURTHER FLEXIBLE DIAPHRAGM COOPERATING WITH SAID CONTROL MEMBER OF WHICH THE DIAPHRAGM ON ONE SIDE IS SUBJECTED TO PRESSURE IN SAID OUTLET PASSAGE.