A lot of people refer to the suspension on the current S-Class as “airbag suspension”, but that’s an inaccurate description. The Active Body Control(ABC) doesn’t employ an airbag at all.
Mercedes Benz deputed ABC on the 1999 CL-Class. But what exactly is it?
With the ABC system, the car sits on 4 fairly ordinary looking struts. Inside each of the struts, there is a big steel spring and a passive damper (so far, just like all struts). The top of each spring is mounted to the sleeve of a hydraulic servo plunger, which is constantly fed with oil at anything up to 200bar of pressure.
In normal driving conditions on untarnished, smooth roads, the spring operates at it’s fullest extension. Which allows the damper itself to work unrestrained. The “damper-alone” ride favours comfort, so you get a nice soft, comfortable ride.
If the car detects(through it’s myriad of sensors) any big movements in either yaw, pitch or roll, it pressurises the plungers independently. So if you corner hard, hit the skids, or hit a big bump, the steel springs inside the struts compress to an appropriate level to compensate.
The system is constantly variable and operates in thousandths of a second, so the car is always maintaining a balance between ride comfort and control in any driving conditions. As well, it allows for weight loading differences in different parts of the vehicle. So a heavier passenger in the back left seat or a big load of goods in the boot is taken into account in all the car’s calculations.
The system is essentially set up to maintain level ride-height between all four corners at all times.
Mercedes have also utilised secondary functionality of the system for the S-Class by allowing the system to analyse the upcoming road surface and raise the ride height automatically for upcoming obstacles (like speed bumps). It can also lower the car at higher speeds.
The way the ABC system functions means that the car feels comfortable without being wallowy and nausea-inducing like an airbag system. It has also allowed the company to get away without fitting any normal, physical anti-roll bars.
Michael Adams from World Car Reviews,
Article Originally Created for Infinite-Garage