Patent ID: 6270168
Filing Date: 2001-08-07
Classification: B60T

Abstract:
A pneumatically-operated braking system for a tractor-trailer combination, in which a trailer control valve for providing braking pressure for the trailer is actuated by a pressure differential acting across it to limit the flow of air in a supply line when a leak is present in a trailer control line, the pressure differential being generated between the pressure in a trailer control line and pressure supply from a trailer/park pressure supply tank, the trailer control valve including a control piston subjected on one face to pressure in the control line which, when in operation, causes the control piston to cooperate with a brake-applying piston to isolate the trailer control line from atmosphere by closing a through bore in a brake-applying piston, further movement of the control piston in the same direction unseating the brake-applying piston from a valve seating to supply pressure to the trailer control line.