DUAL BRAKE VALVE WITH BRAKE PROPORTIONING

摘要

A dual circuit brake valve for an articulated vehicle is responsive to a pressure signal provided by the system tractor protection valve to provide a full brake application in both the primary and secondary braking circuits actuating the front and rear wheel brakes of the vehicle respectively when the portions of the articulated vehicle are connected for movement together. A proportioning piston is responsive to the pressure signal to proportion braking pressure in the secondary when the towing portion of the vehicle is operated in the "bobtail" mode without the towed portion of the vehicle. The brake valve includes mechanism for mechanically actuating the secondary circuit valve to provide a full brake application under emergency conditions during operation of the vehicle in the bobtail node.