Brake pressure control valves

A fluid pressure brake control valve comprising a housing having an inlet and an outlet;

• an internal valve set within said housing for controlling communication between said inlet and said outlet;
• a load conscious member for transmitting an external load to said valve set tending to hold it open, first fluid pressure responsive means exposed to pressure at said outlet and having an operative connection with said valve set tending to close it in response to pressure at said outlet in opposition to the external load transmitted thereto by said load conscious member, another movable valve part in said housing having an operative connection with said load conscious member enabling said other movable valve part and said load conscious member to move in unison or to move relatively with respect to each other, means operable in response to movement of said load conscious member in one direction relative to said other movable valve part to establish free fluid communication between said inlet and said outlet, means operable in response to movement of said load conscious member in unison with said other movable valve part for preventing said operable means from establishing said free communication between said inlet and said outlet so long as the external load acting on said member exceeds a predetermined value, and second fluid pressure responsive means exposed to pressure at said inlet and operatively connected to said load conscious member to move it in said one direction relative to said other movable valve part in response to pressure at said inlet when the external load acting on said member falls below a predetermined value thereby rendering said other movable value part operable to establish said free communication between said inlet and outlet.