Many vehicle systems on a conventional vehicle are negatively affected by the change in attitude coming from changes in load – specifically a heavy suspension system of a car pdf in the rear seat or luggage compartment. Most of the braking power is on the front wheels of a vehicle, which means you will have more effective braking when more weight is over the front wheels. When the rear end has a heavy load, the braking is not as effective. The weight is concentrated on the rear end of the vehicle, and the rear brakes need to do all of the work.
When braking quickly in this situation, the front brakes will be easier to lock up because of the lack of weight transfer to the front of the vehicle. Self-levelling suspension lifts the rear end of the vehicle up to spread out the weight more evenly. This puts the weight back onto the front end of the vehicle, which lets the brakes do their job more effectively. There is an inherent conflict in suspension design – if the springs are soft, the car will be comfortable but dramatically affected by load.
If the springs are hard, the car will be uncomfortable, but less affected by load. These cars maintain an exact height over the road when the engine is on – height control valves attached to the roll bars via linkages would open to add or drain fluid from the suspension, and when the desired height was reached the valve would automatically close due to its design. Later models would use electronic height sensors and motors so adjustment could be achieved with the engine off. Since then, millions of fairly inexpensive Citroën cars have been equipped with self-levelling as an unobtrusive, but integral design feature. Up until 1995 when they added “antisink” to the range when the engine was turned off, the suspension slowly lost pressure until the car rested on the bump stops.
When the engine was restarted it rose back to its pre-selected height. The addition of anti-sink added 2 non-return valves and an extra accumulator so that when hydraulic pressure was lost the valves would close and keep the remaining fluid in the system, and leaving the car resting at a normal height when parked. This early attempt was an important step on the road to self-leveling, even if a full load would cause the whole car to lower evenly, rather than maintain height. 1969 as it had been determined that the rear levelling did almost all the work. Rolls-Royce achieved a high degree of ride quality with this arrangement.
If these were kept soft to maintain comfort they would compress too much under a heavy payload, restricting axle travel when off-road and compromising handling. 1980s when these vehicles adopted the Range Rover’s coil spring suspension. This page was last edited on 7 November 2017, at 06:05. Please forward this error screen to 64. The first vehicle to feature KDSS, the Lexus GX 470. It optimally adjusts front and rear stabilizers based on a set of interconnected hydraulic cylinders. The interconnection is made up of hydraulic piping and a control cylinder which is located at the frame rail.