An air brake control system for use in truck trailers having at each axle compressed-air brakes including spring brakes and service brakes, and each trailer being coupled to receive compressed air through an emergency (supply) gladhand and to receive service brake signals through a service (control) gladhand, the invention comprising an integrated brake valve system for each axle of each trailer, including a common valve housing; a spring brake valve cluster having a non-return check valve connected to receive and pass air pressure from the emergency gladhand and to deliver it directly to the spring brakes and an air pressure responsive shuttle operative to open the check valve whenever the emergency line pressure falls below a predetermined spring brake isolation pressure above which the spring brake holding pressure is not affected by fluctuations of the emergency gladhand pressure; and including an air tank supply valve cluster connected between the emergency gladhand and the tank and operative to sense pressure in the emergency gladhand and to open at a tank-filling threshold pressure above the predetermined spring brake isolation pressure to pass air to the tank and having a tank protecting check valve to prevent backflow of air from the tank; and including a pressure amplifying service brake relay valve cluster connected between the tank and the service brakes to supply and modulate air to the latter responsive to variations in the service gladhand pressure.
An air brake control system for use in truck trailers, including tandem trailers, having at each axle compressed-air spring brakes and service brakes with each trailer being coupled to receive compressed air through an emergency (supply) gladhand and to receive service brake signals through a service (control) gladhand and which includes an integrated brake valve system for each trailer within a common valve housing. Each integrated brake control valve includes a spring brake valve cluster having a non-return check valve connected to receive and pass air pressure from the emergency supply and deliver it to the spring brakes and an air pressure responsive shuttle operative to open the check valve whenever the emergency supply line pressure falls below a predetermined spring brake isolation pressure above which the spring brake holding pressure is not affected by fluctuations of the emergency supply pressure; an air tank supply valve cluster connected between the emergency supply and a reservoir and operative to sense pressure in the emergency supply and to open at a spring brake threshold pressure above the predetermined spring brake isolation pressure to pass air to the reservoir and to close air passage to the reservoir to prevent supply line pressures from dropping below the threshold level during failure of the system elements; and a non-compounding valve cluster for releasing service brake pressure to atmosphere whenever, due to a loss of pressure in the emergency supply lines, the spring brakes have been activated.
A servo-brake-auto-modulator of the kind for use in a trailer provided with a pneumatic braking system is modified so as to enable also the achievement of the functions of an anti-overload valve. To that end a discharge passage (26) which communicates with the atmosphere is formed in an inlet chamber (22) of the body (51) of the servo-brake-auto-modulator (20) in such a position that a control member (47) in one of its working positions, causes a control chamber (33) to be connected to said discharge passage (26), preventing overloading of the parking-brake members (6).
A valve assembly for use in conjunction with spring applied, air release parking brakes of the character found in heavy-duty truck-trailers which, in a single valve housing provides system pressure protection, prevents compounding application of the brakes and performs the parking brake release function in an expedicious and highly reliable manner.
Control valve assemblies for regulating the parking/emergency spring brakes of a tractor trailer air brake system which include valve components for insuring that the spring brakes are not released until pressurization of the system's service reservoir is achieved and which components are operable to exhaust the spring brakes to atmosphere upon the failure of the supply pressures within the system to thereby automatically apply the spring brakes. In one embodiment, the valve components permit pressure to be supplied to release the spring brakes under circumstances when it is not possible to pressurize the service reservoir.
A simplified integrated full-function valve for heavy duty brake systems comprising a valve body having individual ports for fluid communication with spring brake chambers, service brake chambers, pressurized-air reservoir and exhaust and for receiving pressurized control and supply air from respective sources thereof; internal passageways within the valve body providing selected fluid communication with the various ports; a plurality of valve modules within the valve body comprising a spring brake valve module, a relay valve module and a biased one-way pressure protection valve module, and disposed to selectively determine the fluid communications within the internal passageways and ports responsive to the respective positions of the valve modules; the port and related internal passageways for the spring brake chambers being fluid-communicatively-isolated from the reservoir, the service brake chambers and the control air, whereby the number of the internal passageways within the valve body is minimized; the simplified design lending itself to functional flexibility.
