A vehicle height adjustment apparatus includes a control device. The control device controls the opening degree of the solenoid valve to allow a movement amount of the support member to reach a movement amount target value that corresponds to the vehicle height set in advance, in accordance with the weight applied to the vehicle. The control device controls the opening degree of the solenoid valve to change the movement amount of the support member based on a difference between a value based on the information related to the vehicle height and a vehicle height-related target value, on condition that the movement amount of the support member reaches the movement amount target value and the value based on the information related to the vehicle height obtained by the information obtaining device does not reach the vehicle height-related target value that corresponds to the vehicle height set in advance.

An air spring for a heavy-duty vehicle includes a bellows chamber, a piston chamber, and at least one opening. The piston chamber is operatively connected to the bellows chamber. The at least one opening is in fluid communication with the bellows chamber and the piston chamber to provide fluid communication between the bellows chamber and the piston chamber. An orifice assembly is disposed adjacent the at least one opening for variably changing the size of the opening. The air spring provides damping to the heavy-duty vehicle.

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 vehicle height adjustment apparatus includes: vehicle height adjustment units respectively provided to correspond to wheels of a vehicle body, and adjusting a vehicle height in response to the supply and discharge of a working fluid; a pressure tank storing the working fluid; a compressor pressure-feeding the working fluid; a valve body block formed by opening and closing valves, and interposed between the pressure tank and the compressor, and the vehicle height adjustment units; and a control unit adjusting a vehicle height by controlling the valve body block, wherein the valve body block is connected to the pressure tank, and working fluid outlet and inlet of the compressor, and upon the completion of the pressure feed of the working fluid, the control unit controls such that the working fluid outlet and inlet are communicated with each other.

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 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 method for pivoting a travel unit on a machine frame of a road milling machine between an outer end position and an inner end position offset toward a center of the machine relative to the outer end position, the road milling machine having a travel mechanism with multiple travel units, of which at least one travel unit is height-adjustable via a lifting column, comprising the steps of positioning a support foot mounted on the machine frame in a ground contact position to support the machine frame, lifting the travel unit, pivoting the travel unit between the outer end position and the inner end position, lowering the travel unit, and positioning the support foot in a stowed position.

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 suspension system for a vehicle includes a knuckle defining a bore therethrough. The suspension system includes a wheel hub rotatably mounted on the knuckle. Further, the suspension system includes an axle at least partially received within the bore of the knuckle and operatively coupled to the wheel hub. The suspension system includes a pump driven by the axle and configured to generate pressurized fluid. The suspension system includes an actuator receiving pressurized fluid from the pump.

An air suspension system includes an air supply system block including one or more air spring valves, where the one or more air spring valves are disposed within the air supply system block, the air supply system block having a valve block housing. The system further includes the air supply system block pneumatically coupled with one or more air springs, and at least one reservoir coupled with the air supply system block, at least one motor and pump disposed within the air supply system block. The air suspension further includes fast down leveling valves disposed within the air supply system block.

A hydraulic drop frame trailer for a tow vehicle, the hydraulic drop frame trailer including a trailer frame having two sides and a hitch, a pair of wheels, a first and second frame bracket, a trailer bed mounted over the trailer frame, a first and second pivoting hydraulic cylinder, a plurality of hydraulic hoses, a first and second pivoting arm, an operating station connected to a power supply, a first and second axle-less wheel mount with independent suspension mechanism mounted to the first and second pivoting arm, and a plurality of safety locks, each securing an arm to the trailer frame for locking each rotating arm to the trailer bed during transport.