A unitary full-function valve is used to control the operation of a service brake system and a spring brake system. The valve includes a valve body that has multiple ports, including separate ports for providing fluid communication to a spring brake chamber, a service brake chamber, a fluid reservoir and an exhaust port. The valve body also has ports for receiving pressurized supply fluid and control fluid. The supply fluid inhibits the activation of the spring brakes so that the spring brakes are activated when no supply fluid is present. The control fluid is used to activate the service brakes on demand. A biased one-way pressure protection valve is disposed in the valve body to isolate fluid in the service brake system from fluid in the spring brake system when the pressure in the service brake system falls below a variable pressure level. A passageway within the valve body connects the fluid in the spring brake system with the biased pressure protection valve to increase the variable pressure level in proportion to the pressure level in the spring brake system.
A compressed-air supply system for goods vehicles, comprising an air-suspension system and a brake system, wherein the brake system is dimensioned to operate at a lower air pressure than the air-suspension system, and wherein the compressed-air supply system comprises at least one compressed-air tank (43, 51) for supplying the brake system with compressed air. The compressed-air tank (43, 44) is dimensioned for an air pressure which is greater than or equal to the air pressure which is demanded in the air-suspension system and, further, the compressed-air tank is connected to both the air-suspension system and the brake system and comprises compressed-air conduits (40, 40'; 52, 52') through which compressed air can pass by way of one or more outlets in the compressed-air tank (43, 51) to the brake system and the air-suspension system, respectively, wherein a pressure-limiting valve (44, 55) is arranged downstream of the outlet to the compressed-air conduit(s) connecting the compressed-air tank (43, 51) with the brake system.
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.
A braking system is improved by addition of a spring brake pressure protection valve, to prohibit pressurization of the spring brakes prior to the build up of sufficient pressure to insure complete release of the spring brakes. This prevents the significant problems associated with known systems that permit operation of a tractor trailer with partially released spring brakes, which will cause unnecessary wear and reduced fuel economy. The spring brake pressure protection valve is located between the reservoir and the spring brakes, most preferably between the spring brake quick release valve and the spring brakes, or alternately, between the reservoir and the spring brake quick release valve.
A pneumatic valve (10) for selectively controlling fluid flow through a pneumatic system of a vehicle is disclosed. The valve (10) includes a housing (12) having a cavity (28). The cavity includes an inlet (16) and an outlet (18). A flow controller (40) is disposed within the housing (12) for selectively controlling fluid flow through the housing (12). The flow controller (40) is actuatable to an open position, where the inlet (16) is in fluid communication with the cavity (28) and the outlet (18) is in fluid communication with a pneumatically operated device. The flow controller (40) is also actuatable to a closed position, where the flow controller (40) substantially impedes fluid from flowing through the housing (12). The flow controller (40) is actuatable between the open and closed positions in response to a predetermined fluid pressure within the pneumatic system.
