Self-leveling rear suspension components
1 – hydraulic pump; 2 – reservoir; 3 – control unit; 4 – pressure accumulator; 5 – shock absorbers
On the station wagon models with self-leveling rear suspension, the rear shock absorbers have reservoirs with hydraulic fluid. When transporting heavy loads, this fluid, acting on the shock absorbers together with the cylindrical springs of the rear suspension, maintains the required ground clearance of the car. The fluid is supplied to the reservoirs by an electric pump through the control unit and pressure accumulators, which are located in the rear of the car (see picture).
The self-leveling 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 vehicle's load based on the position of the bar.
When the engine is running, the hydraulic pump of the self-leveling rear suspension system supplies pressurized fluid to the system through the control valve. When the vehicle is not loaded, the control valve is closed and the fluid returns to the reservoir located in the engine compartment. In this case, the self-leveling rear suspension system does not have any effect on the operation of the rear suspension, and only the coil springs work.
As the vehicle load increases, the control valve opens and the fluid from the pressure accumulator is supplied under pressure 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 vehicle. After raising the rear of the vehicle to the required height, the control valve returns the fluid to the pressure accumulator. Thus, the control unit maintains the rear of the vehicle at the required level regardless of the vehicle load.
Pressure accumulators have two chambers separated by a rubber diaphragm. One of the chambers is filled with gas under pressure. When the shock absorber is compressed, the fluid from the shock absorber moves into the pressure accumulator, moving the diaphragm and further compressing the gas in the second chamber. If the shock absorber rod comes out of the shock absorber while the car is moving, the fluid under gas pressure moves from the pressure accumulator into the shock absorber.
Checking and repairing the self-leveling rear suspension system must be carried out at a service station using special equipment.
Article based on data from the website: MercedesMan.ru