air suspension system

Air suspension system is an air operated, microprocessor controlled, suspension system that replaces the conventional coil spring suspension and provides automatic front and rear load levelling.
OPERATION:
The air suspension system operates by adding or removing air in the air springs to maintain the level of the vehicle at a pre-determined front and rear suspension height. The pre determined distance is known as the vehicle trim height. The trim height is controlled by the height sensors. Distance of the body to the ground will change with tyre size and inflation pressure.
The height sensors are attached to the body and the suspension arm will lengthen or shorten with suspension travel. Normally three height sensors are used. One for the left front wheel, One for the right front wheel, and another will go to the rear wheels.
The system works in a manner that as the weight is added to the vehicle. The body will settle under the load. As the body lowers, the height sensors shorten creating a signal to the control module(ECU) that activates the air compressor(through a relay) and opens the air spring solenoid valves. As the body rises, the height sensors lenghthen . When the pre set trim height is reached the air compressor is turned "off" and the solenoid valves are closed by the control module.
A similar action takes place whenever weight is removed from the vehicle. As weight is removed, the body will rise, causing the height sensors to lengthen, generating a signal to the control module that opens the air compressor vent solenoid and opens the air spring solenoid valves. As the body lowers, The height sensors shorten and when the pre set trim height is reached, the air compressor vent solenoid is closed and the air spring solenoid valves are closed by the control module.
Air required for levelling the vehicle is distributed from the air compressor to each spring by four nylon lines that start at the compressor dryer and terminate at the individual springs. The dryer contains a desiccant(selica gel) that dries the compressed air before delivering the air to the air springs.