A control valve for use in conjunction of the brake and a combination of the control valve assembly of pneumatic brake of tractor and trailer pneumatic brake set

摘要

A failsafe, foolproof control valve for a tractor-trailer air brake system which, among its other features, permits the tractor brakes to remain in a parked position while the trailer system is being pressurized. The control valve includes four ports, two of which communicate with a first valve chamber and the other two communicate with a second valve chamber. A spring biased first plunger is disposed within the first chamber and a manually operable second plunger extends within the second chamber. Movement of the second plunger establishes several operating modes of the valve to provide various fluid flow paths between the ports in a predetermined manner. At least one of these modes automatically repositions the second plunger to its normal operating mode after the trailer system has been optionally pressurized by actuation of a conventional park valve.