Abstract: A tractor protection valve includes a trailer service brake portion, a trailer parking brake portion, and a stability control portion that are each formed within a common valve body. In one example, the trailer service brake portion includes three inlets that can be used to apply a trailer service brake. The three inlets cooperate with a service brake blocking piston, a service brake relay piston, and double check valves to apply the trailer service brakes as needed. The stability control portion includes a solenoid that can direct air to apply the trailer service brakes in response to a stability control signal. The trailer parking brake portion also includes multiple ports that cooperate with a parking brake piston and valve to control application and release of the trailer parking brakes.

Abstract: A combination quick release and service relay brake valve assembly is used to consolidate multiple valve functions within a common valve assembly, which reduces cost and overall complexity in an associated vehicle brake system. The combination quick release and service relay brake valve assembly includes a valve body with a quick release portion that has a parking brake port and a service brake control port, which is in fluid communication with an anti-compounding passage. The valve body also includes a service relay portion that has a supply port fluidly connected to a service brake air reservoir and a delivery port fluidly connected to a brake actuator that generates service brake requests.

Abstract: A tractor protection valve includes a trailer service brake portion, a trailer parking brake portion, and a stability control portion that are each formed within a common valve body. In one example, the trailer service brake portion includes three inlets that can be used to apply a trailer service brake. The three inlets cooperate with a service brake blocking piston, a service brake relay piston, and double check valves to apply the trailer service brakes as needed. The stability control portion includes a solenoid that can direct air to apply the trailer service brakes in response to a stability control signal. The trailer parking brake portion also includes multiple ports that cooperate with a parking brake piston and valve to control application and release of the trailer parking brakes.

Abstract: A brake system for a tractor-trailer vehicle includes a service brake system and a park brake system. The service and park brake systems are used to brake both a tractor and a trailer towed by the tractor. A trailer hand control valve is actuated by a vehicle operator to brake the trailer. The park brake system includes a park brake control valve that receives input commands from the vehicle operator to apply and release park brakes on the tractor and the trailer. An interlock valve assembly fluidly connects the park brake control valve to primary and secondary air supplies. The trailer hand control valve is also fluidly connected to the interlock valve assembly. The interlock valve assembly includes an outlet port that supplies an air signal to the trailer from one of the primary air source, secondary air source, or trailer hand control valve via a single connection line.

Abstract: A combination valve assembly provides dual functionality within a single valve housing. In one example, the valve operates as a combination inversion valve and quick release valve. In another example, the combination valve operates as an inversion valve and a relay valve. The valve is particularly useful for controlling the operation of a spring applied, air release brake actuator in a heavy vehicle braking arrangement. A valve designed according to this invention preferably also provides anti-compounding features.

Abstract: A combination valve assembly provides dual functionality within a single valve housing. In one example, the valve operates as a combination inversion valve and quick release valve. In another example, the combination valve operates as an inversion valve and a relay valve. The valve is particularly useful for controlling the operation of a spring applied, air release brake actuator in a heavy vehicle braking arrangement. A valve designed according to this invention preferably also provides anti-compounding features.

Abstract: A piston assembly including a piston having a work surface, a sidewall extending from the work surface, and ports in the sidewall. The piston assembly also includes a flexible lubricant-scraping ring clamped to the piston between the work surface and the ports, with the lubricant-scraping ring having an outer edge extending outwardly beyond the sidewall.

Abstract: An isolation valve is provided for use in a pneumatic system having an air compressor operable in normal and unloading modes, an air dryer, a reservoir of charged air, and a governor. The isolation valve includes a housing provided with an internal cavity and having a first port to the cavity communicating with a first port of the compressor, a second port to the cavity communicating with an inlet port of the dryer, and a third port to the cavity communicating with a port of the governor. A pneumatically responsive primary valve member is mounted within the cavity for movement between open and closed positions with respect to the housing second port. The primary valve member is provided with an internal passage having one end in communication with the housing third port and a second end in communication with the housing cavity. A pneumatically responsive secondary valve member is mounted within the passage for movement between blocking and unblocking positions.

Abstract: A gas charged accumulator includes a gas chamber and a hydraulic reservoir on opposite sides of a movable member. A fill passage for pressurizing the gas chamber includes a movable operating device for operating an indicator when the accumulator is substantially discharged. Gas flows directly past the indicator operating device when the gas chamber is pressurized through the fill passage. A normally closed switch assembly is mounted in the fill opening outwardly of the indicator operating device subsequent to pressurization of the gas chamber. The indicator operating device holds the switch assembly in an open position when the accumulator is charged and provides closing of the switch when the accumulator is substantially discharged.

Abstract: A combined hydraulic and vacuum booster includes hydraulic and vacuum boosters coaxially mounted in series and having a common force output member. The combined booster includes common operating means for energizing the boosters in sequence for first applying substantially the full force of the hydraulic booster to the output member while the vacuum booster is substantially inoperative, and then applying the force of the vacuum booster to the output member.