A full function valve incorporating a proportioning valve module that initially directs supply air pressure during initial system charging to the spring brake chambers to prepare the spring brakes for prompt release when there is sufficient system supply air pressure to operate the service brakes. The proportioning valve module then opens to increase supply air pressure to the reservoir, while charging of the spring brake chambers continues, until the service brakes become operable and the spring brakes disengage.
The invention relates to a level control arrangement for vehicles having air springs (6a) to (6d) and a pneumatically controllable directional valve (26). A residual pressure holding function and an overpressure function are integrated into the directional valve (26). The directional valve (26) is controlled by the air pressure in the air springs (6a) to (6d). The air pressure can be applied via a control line (20) to a control input (24) of the directional valve (26). The air from the air springs (6a) to (6d) is released with the aid of the venting line (28). The venting line (28) is guided separately from the control line (20) through the directional valve (26). In this way, a large air flow can be conducted through the venting line (28) without the static air pressure in the control space (50) of the directional valve (26) being reduced. The venting line is blocked by a stepped piston (44) of the directional valve when no air is to be released from the air springs.
A braking system control requires that a first or service braking system be actuated before a second or parking braking system can be released to prevent unexpected movements. A sensor senses that the service brakes are engaged and controls a device to release the parking brakes. A latch ensures that the parking brakes remain released. For example, a piston and check valve form the sensor and latch. Service brake pressure works against the piston. Above a threshold level, service brake pressure drives the piston to open a valve that provides pressurized air to a parking brake release system. Once released, the check valve directs parking brake release pressure to the piston to keep the valve open.
The present invention relates to a brake assembly for a vehicle having an air spring wherein a brake signal operates a brake cylinder of the vehicle. A proportioning valve, having its load responsive element disabled and being responsive to the brake signal, provides a proportioned brake signal to the brake cylinder. A switch, responsive to an air spring pressure signal selectively connects the brake signal to the brake cylinder. The present invention further relates to a method for retrofitting a brake system by disabling the load sensing element of a proportioning valve and inserting a switch in parallel with the proportioning valve.
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 valve assembly for an air pressure system includes an inlet valve, a first control valve, and a second control valve. The inlet valve includes an inlet port, an outlet port and a control port. The inlet valve inlet port communicates with the inlet valve outlet port when the inlet valve control port is above a threshold pressure. The first control valve includes an inlet port, an outlet port, an exhaust port, and a control member. The first control valve inlet port communicates with the inlet valve outlet port. The first control valve outlet port communicates with one of the first control valve inlet port and the first control valve exhaust port as a function of a position of the first control valve control member. The second control valve includes an inlet port, an outlet port, an exhaust port, and a control member. The second control valve inlet port communicates with the inlet valve outlet port. The second control valve outlet port communicates with one of the second control valve inlet port and the second control valve exhaust port as a function of a position of the second control valve control member.
