Self-levelling rear suspension elements
1 - hydraulic pump; 2 - tank; 3 - control unit; 4 - pressure accumulator; 5 - shock absorbers
On Wagon models with self-leveling rear suspension, the rear shock absorbers have hydraulic fluid reservoirs. When transporting heavy loads, this fluid, acting on the shock absorbers, together with the coil springs of the rear suspension, maintains the required vehicle clearance. Liquid is supplied to the tanks by an electric pump through the control unit and pressure accumulators, which are located at the rear of the vehicle (see picture).
The self-levelling rear suspension system is controlled by a unit mounted on the bottom of the vehicle. The control unit is connected to the rear anti-roll bar and determines the amount of vehicle loading by the position of the stabilizer.
When the engine is running, the self-levelling rear suspension system's hydraulic pump supplies pressurized fluid to the system through the control valve. If the car is not loaded, the control valve is closed and the fluid returns to a reservoir located in the engine compartment. In this case, the self-levelling rear suspension system has no effect on the operation of the rear suspension, and only the coil springs work.
As the vehicle load increases, the control valve opens and pressurized fluid from the pressure accumulator is supplied to the shock absorber reservoirs. As a result, the pressure in the shock absorbers increases and the shock absorber rod, leaving the shock absorber, lifts the rear of the car. After raising the rear of the vehicle to the required height, the control valve returns fluid to the pressure accumulator. Thus, the control unit maintains the rear of the car at the required level, regardless of the load on the car.
Pressure accumulators have two chambers separated by a rubber diaphragm. One of the chambers is filled with pressurized gas. When the shock absorber is compressed, the fluid from the shock absorber moves into the pressure accumulator, moving the diaphragm and additionally compressing the gas in the second chamber. If the shock absorber rod comes out of the shock absorber when the vehicle is moving, the fluid under gas pressure moves from the pressure accumulator to the shock absorber.
Checking and repair of the self-leveling rear suspension system must be carried out at a service station using special equipment.