Suspension Control ( Automatic - Electronic ): Description and Operation

Ride Leveling





The Nivomat ride levelling system improves ride quality by allowing the use of softer road springs, while controlling the effects on the suspension of a fully laden vehicle. The system uses special rear dampers in place of the normal units. There are no other components in the system. The ride levelling system is completely automatic, requiring no input from the driver.

Ride levelling may be specified as an option on certain models; it is not available in north American markets. Ride levelling and adaptive damping are mutually exclusive options.

The Nivomat damper:
^ Supplements the load-carrying capacity of the road springs at high vehicle loads.
^ Uses road inputs to the suspension to power the levelling function.
^ Detects suspension height directly from road wheel travel.
^ Provides load-dependent spring rates; the accumulator gas pressure increases with load.
^ Provides load-dependent damping; the fluid pressure increases with load.


Operation
Following an increase in vehicle loading, the dampers adapt to maintain the height of the vehicle within its design range. The system uses road inputs to the suspension to power the levelling action, and requires up to approximately two kilometers of travel, following a change in load, to complete the process.

Normal movement of the suspension causes a pumping action to occur within the damper, as a result of extension and compression of the pump rod in the pump chamber. Hydraulic fluid is pumped from the pump chamber into a high pressure gas accumulator. The increase in gas pressure augments the force developed between the vehicle axle and the body, thereby providing lift.

A control orifice in the pump rod determines the levelling height. When the damper is compressed, this orifice is covered. When the damper extends, the control orifice is uncovered, pressure is released to the low pressure oil reservoir and the system ceases to rise. When the vehicle is high after unloading, the opened control orifice allows fluid to be returned to the low pressure oil reservoir, and the suspension returns to its normal unladen height.