Expedition 4WD V8-281 4.6L SOHC (1998)
Air Spring: Description and Operation
Rear Air Spring
The 4WAS vehicles use a pneumatic spring in the rear. The pneumatic spring is essentially a column of gas confined in a container, utilizing the pressure
of the gas as the force medium of the spring. The ability of the gas to compress provides the desired elasticity for the spring. The air suspension system
regulates the pressure in each air spring by compressing and venting system air. Increasing air pressure (compressing) raises the vehicle; decreasing air
pressure (venting) lowers the vehicle. Vehicle height is maintained by the addition and removal of air in each air spring through an integral solenoid
assembled to the upper spring cap and energized through the control module command.
The air spring assemblies are mounted between the axle spring seats and the frame upper spring seats.
The air springs replace the conventional coil springs.
