An air suspension system includes air suspensions (1, 2) performing vehicle height adjustment in response to supply and discharge of air, a compressor (3) compressing air, a tank (4) storing compressed air, a first passage (6) connecting between the delivery side of the compressor and the tank, and a second passage (7) connecting between the delivery side of the compressor and the air suspensions. A first dryer (10) is provided in the middle of the first passage to dry air flowing through the first passage. A second dryer (11) is provided in the middle of the second passage to dry air flowing through the second passage. Thus, compressed air generated from ambient air sucked in by the compressor can be dried by the second dryer and supplied directly into the air chambers of the air suspensions.

An air management system for a vehicle having a first pneumatic circuit and a second pneumatic circuit, in which the first and second pneumatic circuits are pneumatically connected in a neutral position via a cross-flow mechanism. The first pneumatic circuit includes a first leveling valve configured to adjust independently the height of a first side of the vehicle. The second pneumatic circuit includes a second leveling valve configured to adjust independently the height of a second side of the vehicle. The first and second leveling valves are configured to establish pneumatic communication between the first and second pneumatic circuits when the first leveling valve is not independently adjusting the height of the first side of the vehicle and the second leveling valve is not independently adjusting the height of the second side of the vehicle.

A compressed air supply installation for operating a pneumatic installation, especially an air suspension installation of a vehicle, includes a compressed air supply unit, a compressed air port towards the pneumatic installation, a venting port towards the surroundings, a first pneumatic connection between the compressed air supply and the compressed air port, the first pneumatic connection having an air drier and a shut-off valve, and a second pneumatic connection between the compressed air port and the venting port. The shut-off valve is a pneumatically pilot-controlled check valve.

This lift axle device comprises: a first air spring which corresponds to a first axle; a second air spring which corresponds to a second axle that reciprocates between a down position and lift position; an air bellows; a pneumatic circuit which has a solenoid valve; and a control circuit. The control circuit controls the supply of electric power to the solenoid valve. If the pressure transitions to less than a first pressure, the second axle is placed in the lift position. If the pressure transitions to at least a second pressure, the second axle is placed in the down position. If the pressure transitions to at least the first pressure and less than the second pressure, the second axle is caused to maintain the position thereof.

An air suspension system includes a tank, a tank-side open/close valve, an air suspension-side open/close valve, a system portion, and the like. The system portion includes a compressor, an air drier, and a first passage and a second passage provided between the tank-side open/close valve and the air suspension-side open/close valve in parallel, a discharge valve, a tank-side control valve, an air suspension-side control valve, and the like. Due to this configuration, the air suspension system regenerates the air drier by opening the discharge valve to thus cause the air in the second passage to flow from an opposite side toward one side of the air drier when no power is supplied to the tank-side control valve and the air suspension-side control valve.

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 air management system for a vehicle having a supply tank, a system controller integrated with the supply tank, a first pneumatic circuit pneumatically connected to the system controller, and a second pneumatic circuit pneumatically connected to the system controller. The system controller adjusts independently air pressure of the first pneumatic circuit and the second pneumatic circuit without establishing pneumatic communication between the first and second pneumatic circuits. The system controller establishes pneumatic communication between the first and second pneumatic circuits when the system controller is not adjusting independently the air pressure of the first pneumatic circuit and the second pneumatic circuit.

A compressed-air feed system for operating a pneumatic system includes a compressed-air supply, a compressed-air connection to the pneumatic system, a ventilation connection to surroundings, and a pneumatic main line between the compressed-air supply and the compressed-air connection. The pneumatic main line has an air dryer and a regeneration throttle. The compressed-air feed system further includes a ventilation line between the pneumatic main line and the ventilation connection. The ventilation line has a ventilation valve and a ventilation throttle. The compressed-air feed system further includes a bypass line between the compressed-air connection and the air dryer. The bypass line has a bypass valve formed as a 2/2 directional valve configured to permit an air flow conducted via the air dryer, and bypassing the regeneration throttle, for filling and ventilating the pneumatic system.

A towable vehicle including a chassis, at least two wheels and a suspension assembly supporting each wheel. The suspension assembly includes a swing arm pivotally mounted to the chassis, an axle mounted proximate an end of the swing arm, the wheel being mounted on the axle, at least one shock absorber extending from the chassis to the swing arm, an airbag swing arm mounting pivotally coupled to the swing arm, an airbag chassis mounting coupled to the chassis, an airbag coupled to the airbag swing arm and airbag chassis mountings so that inflation of the airbag allows a suspension height to be adjusted over an operating range and a pivot arm pivotally mounted to the chassis and the airbag swing arm mounting to maintain an orientation of the airbag swing arm mounting over the operating range.

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).