A vehicle-height control system including a tank, a compressor, an actuator, and a valve between the tank and the compressor. The valve is closed to a state of a pressure medium supplier to the compressor-pressure supply state when a tank pressure has reached a threshold in a tank-pressure supply state in which the tank pressure is supplied to the actuator. In the compressor-pressure supply state, the tank pressure is kept at the threshold, and a pressure in the actuator is greater than the tank pressure. The threshold makes it difficult for a pressure differential in the valve to become greater than a valve-opening pressure differential, making it difficult for the valve to be opened in the compressor-pressure supply state. This system enables good supply of a pressure medium from the compressor to the actuator, avoiding a longer time for vehicle height control and achieving a shorter compressor operation time.

An axle/suspension system for a heavy-duty vehicle including a wheel and a sensor. The sensor is operatively connected to an air spring mounted on the axle/suspension system and is capable of detecting a condition of a road or the heavy-duty vehicle. The air spring has a stiffness capable of being altered in response to the sensor and to reduce resonant load variation on the wheel.

A housing includes an air introduction flow passage, an air discharge flow passage, and a desiccant agent accommodated in the housing. One end portion of the housing is at a lower side of the housing in a vertical direction aligned with the axial direction. An air-liquid separation chamber is formed at a bottom portion of the housing, and includes an air supply passage supplying air to the desiccant agent at an upper housing surface, and is communicated with the air introduction flow passage and the air discharge flow passage to separate moisture in the air introduced from the air introduction flow passage. An adsorption member is accommodated in the air-liquid separation chamber to adsorb moisture separated in the air-liquid separation chamber. Air introduced from the air introduction flow passage is supplied to an air suspension device through the adsorption member and the desiccant agent.

A shock absorber includes a gas spring cylinder containing a piston moveable between an extended position and a compressed position within the gas spring cylinder. A mechanical actuator is arranged whereby a bleed port is automatically closed when the gas spring is compressed to a predetermined position corresponding to a desired sag setting. In one embodiment, the position corresponds to a predetermined sag setting whereby the gas spring is partially compressed. In another embodiment, a proper sag setting is determined through the use of a processor and sensor that in one instance measure a position of shock absorber components to dictate a proper sag setting and in another instance calculate a pressure corresponding to a preferred sag setting.

A spring-absorber system for a wheel suspension of a motor vehicle includes a suspension spring with a spring constant k.sub.T and an absorber filled with a fluid and mounted in parallel to the suspension spring. The spring-absorber system also includes at least two additional spring modules via which a total spring constant k.sub.G of the spring-absorber system can be varied.

A vehicle is provided with a vehicle frame or sub-frame structure and at least one of a body structure and engine structure or a plurality of suspension components mounted to the vehicle frame or sub-frame structure and a plurality of fluid-controlled spring/dampers supporting the least one of a body structure and engine structure or a plurality of suspension components to the vehicle frame of sub-frame structure, the plurality of fluid-controlled spring/dampers being connected to a single central pump.

A compressed-air supply system for operating a pneumatic installation includes a reservoir, a number of bellows, a pressure-air feed to which a charging assembly having a compressor is connected on a pressure-medium feed side, a pressure-air connection to the pneumatic installation, a venting connection to the environment, a pneumatic main line between the pressure-air feed and the pressure-air connection, a vent line between the pressure-air feed and the venting connection and a changeover valve associated with the pressure-air feed and configured to be controlled by pressure air in such a way that the pressure-air feed is open or can be opened via the changeover valve to the main line. A flow pressure at the pressure-air feed can be generated by the charging assembly to the main line.

An air management system and method are provided. The system includes a pressurized air source. A manifold block is coupled to the pressurized air source and includes a plurality of suspension valves in fluid communication with the pressurized air source for controlling air flow to and from a plurality of air springs. An accumulator is coupled to the manifold block for storing air. An accumulator valve is in fluid communication with the plurality of suspension valves and the accumulator to allow exhausted air from the plurality of air springs into the accumulator. An electronic control unit is electrically coupled to the plurality of suspension valves and the accumulator valve for controlling a sequence of operating the accumulator valve and the plurality of suspension valves to provide enhanced exhaust flow from the plurality of air springs to maintain the vehicle in a level orientation while lowering the vehicle.

A leveling valve (101) for discharging and supplying air from and to a plurality of utilization elements (205a, b), in particular pneumatic suspension bellows, includes a valve arrangement (103) for directing air between a source (207) of pressurized air, an exhaust port (3) and the utilization elements, a supply port (1) in fluid communication with the valve arrangement (103) and the source (207) of pressurized air, and an exhaust port (3) having an exhaust air channel (a) for discharging exhaust air. The exhaust port (3) includes at least one air-permeable damping element, which is at least partly positioned within the exhaust air channel (a).

A leveling valve (101) for discharging and supplying air from and to a plurality of utilization elements (205a,b), in particular pneumatic suspension bellows, includes a valve arrangement (103) for directing air between a source (207) of pressurized air, an exhaust port (3) and the utilization elements (205a,b), and a supply port (1) in fluid communication with the valve arrangement (103) and the source (207) of pressurized air. A check valve (5) is mounted upstream of the valve arrangement (103) and is configured to allow fluid flow from the supply port (1) towards the valve arrangement (103) and to block fluid flow from the valve arrangement (103) through the supply port (1).