The CDC (continuous damping control) shock absorbers, similar to those that Audi already uses on the luxury Audi Q7 SUV with air suspension, are twin-tube, gas-filled hydraulic units with an additional external valve and connecting pipe. Their operation can be continuously varied.
An electromagnetically energized, proportional-action valve regulates the flow of hydraulic fluid between the inner and outer damper tubes. A smaller flow cross-section makes the damping characteristic firmer, a larger one makes it softer.
The control unit applies adaptive operating characteristics within the mode the driver has chosen via Audi drive select. It adapts to match the driver’s driving style and the road conditions. Even from the comfort mode, the shock absorbers can be switched in an instant to a firm setting if desired, though not to the absolute limit. They are fitted in conjunction with sports suspension springs, which still provide a good level of ride comfort, even off-road.
The control unit selects the optimum damping force for the current driving situation, for instance firmer damping to prevent body roll and pitch when cornering fast or braking, or lower damping force where the surface under the wheels is hard and uneven.