Expedition 2WD V8-5.4L SOHC VIN L (1997)
Air Spring: Description and Operation
Rear Air Suspension
The RAS 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 rear of the vehicle
decreasing air pressure (venting) lowers the rear of 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 two air springs replace the conventional rear
coil springs. The air springs store compressed air from the air compressor and raise and lower the rear end of the vehicle by compressing air in the air
springs or releasing air from the air springs.