The suspension system of the present invention includes an elongated spring having one end attached to the vehicle frame and having a second end. A pneumatic bag includes an upper end which is attached to the vehicle frame and a lower end. A securing bracket attaches the lower end of the bag and the second end of the elongated spring to the axle so that the weight of the vehicle frame above the axle is supported in combination by the spring and the air bag. A pneumatic control system is in communication with the bag for selectively introducing air to the bag so as to control the pressure within the bag and thereby control the height that the bag supports the vehicle frame above the axle. A stabilizer bar is pivotally connected at one end of the vehicle frame and at the other end to the axle so as to cause the vehicle frame to be centered over the axle while at the same time permitting the vehicle frame to move vertically with respect to the axle. The control means includes both manual controls and automatic photo-electric sensors for controlling the height of the frame above the axle.
