The present invention is a pulse valve which imparts a force to a piston means for a limited duration of time or over a given distance. This pulse valve can be incorporated into a manual control valve. The manual control valve is particularly useful in an air parking brake control system for an air parking brake system.

Disclosed is a positive-pressure air brake system for a highway tractor and trailer combination in which the conventional mode of tractor-to-trailer control line connection is avoided and supplanted by a sub-system in which the trailer control line pressures are developed from the tractor supply line rather than its control line through a valve assembly which responds to tractor control line pressures in relay fashion to dispense brake-operating pressures to the control line of the trailer. This...

A pneumatic brake system employing dual-diaphragm, spring-actuated, air-released brake actuators is provided with an inversion valve which, in the event of a brake system failure, prevents the brakes from being automatically applied while permitting controlled brake application by releasing compressed air from each actuator's spring chamber in an inverse ratio to that normally supplied from the system by the operator applied brake valve thus permitting a controlled spring brake application. The ...

An exhaust valve assembly includes a housing having a plurality of ports and a flexible diaphragm movable between opposite positions for selectively connecting the ports. A central elongated stem on the diaphragm extends tightly through a hole in the housing for minimizing vibration of the diaphragm.

A vehicle air brake system includes spring set air released parking brakes to which air is supplied through a pressure holding valve which maintains the air chambers of the parking brakes at a predetermined pressure even though the air brake system may be at operating pressures substantially lower than the predetermined pressure. When the air pressure in the air brake system falls below operational levels, the pressure holding valve responds to release the air from the parking brake chambers. Th...

An air brake system for a vehicle having front service and parking brakes, and rear service and parking brakes, includes separate front service, rear service and parking air systems. In the event of a failure in either service air system, normal operation of the service brake control will automatically operate the parking brakes associated with the failed service brakes.

A vehicle air brake system includes spring set air released parking brakes to which air is supplied through a pressure holding valve which maintains the air chambers of the parking brakes at a predetermined pressure even though the air brake system may be at operating pressures substantially lower than the predetermined pressure. When the air pressure in the air brake system falls below operational levels, the pressure holding valve responds to release the air from the parking brake chambers.

A pneumatic brake system employing dual-diaphragm, spring-actuated, air-released brake actuators is provided with an inversion valve which, in the event of a brake system failure, prevents the brakes from being automatically applied while permitting controlled brake application by releasing compressed air from each actuator's spring chamber in an inverse ratio to that normally supplied from the system by the operator applied brake valve thus permitting a controlled spring brake application. The ...

Disclosed below is a valve constructed with an electrical circuit extending through separable flow-control elements of the valve whereby the circuit may be opened by actual parting of the separable elements. For specific uses, the valve is characterized by structure permitting instant opening to full flow, high flow capacity, self-opening action, and latching mechanism for locking it in closed position.

A pneumatic brake system is provided for tractor-trailer vehicles which permits air to be supplied to the trailer while both tractor and trailer brakes remain set when the rig is parked thereby permitting associated pneumatic devices to be operated with the rig braked. The system includes a park valve which, by itself, is operable to always set the tractor-trailer brakes when the vehicle is parked and release same when the vehicle is to be driven. A control valve is provided in the system which,...