Self-levelling suspension – composition (S.W.)

The BOGE Nivomat self-levelling units used on the Alfa 156 Sport Wagon consist of an outer shell containing two chambers:

the low-pressure chamber (1), located at the bottom, acts as the fluid reservoir and is partially filled with gas under pressure;

the high-pressure chamber (2), located at the top of the unit, is divided in two by a membrane (2); the external part contains the pressurized gas, while the inner part is filled with fluid.

Unladen, the pressure inside the two chambers is identical, about 25 bar; fully laden, the low-pressure chamber is at about 8 bar, while the high-pressure chamber reaches about 80 bar.

The outer casing contains the actual cylinder of the shock absorber (4), to the stem (5) of which is connected the piston (6) with the damping valves.

A perforated pumping stem (7), connected to the base of the unit, runs along the inside of the hollow piston, forming the fluid pump (8).

On the outer surface of the stem (7) there is a hole (9), which acts as a height sensor.

Hydraulic diagram of the Nivomat unit.

Cross-section of the Nivomat unit.