A vehicle height control system includes a fluid feeder and a vehicle height control unit. The vehicle height control unit includes a communication control unit. In a first communication state, a high-pressure source and a common passage are made to communicate with each other via the first passage and the second passage. In a second communication state, the first passage is shut off and the high-pressure source and the common passage are made to communicate with each other via the second passage. The communication control unit selects one from among the plurality of communication states based on at least one of a content of a start condition, a target vehicle height of a height increasing control and a number of wheels to be controlled in the height increasing control, when the start condition of the height increasing control is satisfied.

A vehicle suspension connects a vehicle body to a plurality of wheels and allows relative motion between the vehicle body and the wheels. The suspension system includes a plurality of telescoping multi-stage hydraulic cylinder assemblies arranged to selectively lift the vehicle body relative to the wheels when extended and to lower the vehicle body relative to the wheels when contracted. A control valve is used to adjust a volume of hydraulic fluid in the hydraulic cylinder assemblies to change a height of the vehicle. External spring packs are in fluid connection with the hydraulic cylinder assemblies to maintain spring forces on the suspension system over a range of telescopic movement of the hydraulic cylinder assemblies. Fluid damping valves are provided for damping telescopic movement of the hydraulic cylinder assemblies by restricting fluid flow between the hydraulic cylinder assemblies and the spring packs.

A vehicle-height adjustment system includes: a vehicle-height adjustment actuator provided so as to correspond to a wheel; and a pressure-medium supply and discharge device configured to supply and discharge a pressure medium to and from the vehicle-height adjustment actuator. The pressure-medium supply and discharge device includes a tank configured to store the pressure medium. The vehicle-height adjustment system includes a tank-pressure controller configured to control a tank pressure based on at least one of a vehicle height for the wheel and an inside temperature. The tank pressure is a pressure of the pressure medium stored in the tank, and the inside temperature is a temperature in the vehicle-height adjustment system.

A reciprocating-piston machine includes at least one first cylinder and at least one first piston assigned to the first cylinder as well as at least one second cylinder and at least one second piston assigned to the second cylinder. During operation, the first piston and the second piston are deflected in a respective cylinder displacement chamber of the respective first cylinder and the second cylinder. The reciprocating-piston machine further includes a crankshaft which, during operation, can be driven and which has an eccentric crankshaft journal and a drive shaft coupling designed for the coupling of a drive shaft of a drive motor for driving the crankshaft. Additionally, the reciprocating-piston machine includes a first connecting rod configured to deflect the first piston, a second connecting rod configured to deflect the second piston, and a bearing pin about which the first and second connecting rod are rotationally movable.

A plurality of traveling wheels are supported via expandable/contractible tubular support members to a vehicle body frame. A hydraulic operation type vehicle height adjustment mechanism is provided for each one of the traveling wheels, the vehicle height adjustment mechanism being capable of switching a relative height of the traveling wheel relative to the vehicle body frame within a predetermined length range by expanding/contracting the support member by a hydraulic cylinder. There are provided a hydraulic control valve capable of controlling feeding state of work oil to each one of the plurality of hydraulic cylinders, a controlling section for controlling an operation of the hydraulic control valve to bring the vehicle body to a target state via vehicle height adjustment by the hydraulic cylinder in response to a change in the posture of the vehicle body and a plurality of accumulators connected oil chambers of the respective plurality of hydraulic cylinders.

A mechanically actuated level control valve device for a commercial vehicle with an air suspension system is a level control valve and comprises a drive element that can be mechanically coupled to a vehicle wheel or axle. A valve element and a counter valve element have a first relative position, wherein the port for the air suspension bellow is closed, a second relative position, wherein the port for the air suspension bellow is connected to the port for the aeration device, and a third relative position, wherein the port for the air suspension bellow is connected to the port for the deaeration device. The valve element is coupled to a rotatable driveshaft of the level control valve by a drive mechanism. An integrated actuator changes the relative position of the valve element and the drive element or the relative position of the counter valve element and a valve housing.

An air suspension system of a commercial vehicle comprises an electronic control device with a level control valve device. A valve element is coupled to a drive element mechanically coupled to a vehicle wheel or axle. In a first relative position of the valve element and a counter valve element, a port for an air suspension bellow is blocked. In a second relative position, the port for the air suspension bellow is connected to a port for an aeration device. In a third relative position, the port for the air suspension bellow is connected to a port for a deaeration device. Control logic generates a control signal for an actuator which, when a level change is set by an operator, correspondingly changes the relative position of the valve element and the counter valve element or the relative position of the counter valve element and a valve housing.

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).

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 vehicle includes an outside sensor configured to acquire information on an outside circumstance of the vehicle, a vehicle height adjusting device configured to adjust a vehicle height, and a control device configured to control the vehicle. The control device is configured to control the vehicle height adjusting device such that the vehicle height becomes a vehicle height corresponding to a platform condition at a predetermined stop position when the vehicle stops at the predetermined stop position. The control device is configured to control the vehicle height adjusting device based on a height of an obstacle such that the obstacle does not interfere with the vehicle when the obstacle is detected at the predetermined stop position by the outside sensor.