Precise wheel location and extremely effective anti-roll control are the major advantages of the newly developed rear axle. These two attributes make their presence felt even more strongly in an innovative vehicle concept such as the A-Class, whose particular centre of gravity would normally require a fairly stiff chassis setting. However, this special axle technology allows a more comfortable setting for the springs and damping – without detracting from the outstanding road-holding characteristics of the new Mercedes compact car. The camber angle of the wheels remains constant regardless of the driving situation, allowing higher lateral forces to be transferred be-tween the tyres and the road surface – particularly through corners – than is possible with a conventional link axle. This effect also influences the car’s tendency to under-steer, an important factor in the A-Class’ high level of active safety. Thanks to the innovative axle technology, the new model’s handling remains stable, sporty and pre-cise even when the car is carrying a load or operating at the limit.

A key attribute of the spherical parabolic- spring rear axle is the raised momentary centre of rotation – i.e. the pivot point around which the body leans to the side through corners. The distance between the momentary centre of rotation and the vehicle’s centre of gravity above it results in the lever arm, which influences the extent of the rolling motion. With the Mercedes rear axle, the momentary centre of rotation lies 280 millimetres above the road and therefore closer to the vehicle’s centre of gravity. The short lever arm prevents the rolling motion caused by vehicle lean.

The momentary centre of rotation remains constant in any situation out on the road. Even when the A-Class is fully loaded, this pivot point is only lowered by some 48 mil-limetres.

Due to the high momentary centre of rotation of the car’s rear axle and the low posi-tioning of the front axle, the roll axis of the new A-Class rises to the rear. This results in reduced body movement – a positive development which really comes into its own if the driver switches to a more dynamic driving style.

This innovative axle technology allows comfortable spring and damper ratios. The rear axle of the new A-Class features coil springs, single-tube shock absorbers and an anti-roll bar. The springs and dampers are positioned separately. The large elastomer central bearing, which links the axle housing with the car body, also ensures good structure-borne soundproofing and minimises vibrations.