The ABC system from Mercedes Benz

Function and mode of operation of the ABC chassis

Active Body Control (ABC) is the Mercedes-Benz brand name used to describe the fully active suspension that controls vehicle body movements and virtually eliminates rolling away in many driving situations, including cornering, accelerating and braking.

Technical drawing of the ABC chassis
Technical drawing of the ABC chassis (source: Mercedes Benz)

In the ABC system, a control unit detects the movement of the body using sensors located throughout the vehicle and controls the action of the active suspension using hydraulic servomechanisms.

Mercedes control unit
Mercedes control unit

The hydraulic pressure to the shock absorbers is supplied by a high pressure radial piston hydraulic pump. A total of 13 sensors continuously monitor the movement of the body and the vehicle position and supply the ABC control unit with new data every ten milliseconds.

ABC pump servo pump A0034662301 Mercedes S Class W220 400 CDI V8 biturbo diesel
Mercedes hydraulic pump

Four level sensors, one on each wheel, measure the driving level of the vehicle, three accelerometers measure the vertical body acceleration, one acceleration sensor measures the longitudinal and one sensor the transverse body acceleration. A pressure sensor monitors the hydraulic pressure on each hydraulic cylinder. While the ABC control unit receives and processes data, it operates four hydraulic servos, each of which is mounted in a row next to each wheel on a spring strut. Almost immediately, the servo-controlled suspension generates counter-forces against leaning, diving and kneeling of the vehicle during the various driving maneuvers.

Mercedes shock absorbers
Mercedes shock absorbers

A suspension strut, consisting of a steel coil spring and a shock absorber, which are connected in parallel, as well as a hydraulically controlled actuating cylinder are arranged between the vehicle body and the wheel. These components are prone to failure and dangerous if they fail. The system also has height-adjustable suspension, which in this case lowers the vehicle by up to 60 mm between speeds of 160 and 11 km / h in order to improve aerodynamics, fuel consumption and handling.