Brake Assist Systems

The dynamic handling control systems ABS and ESP assist the driver in critical situations. ESP assists the driver in extreme situations by trying to prevent the vehicle from skidding by controlled application of the brakes and intervention in the engine management. ABS keeps the vehicle steerable when braking hard so that the driver can steer around an obstacle, thus helping to avoid a collision. It is, of course, safer and better to come to a standstill in front of the obstacle. And this is where the Volkswagen brake assist systems come in, making an important contribution to safety.

 

Brake assist

The most common cause of a rear-end collision is that, although some drivers react quickly when emergency or panic braking, they do not press the brake pedal down hard enough. As a result, the vehicle is not decelerated with the maximum braking power, the braking distance is extended and the risk of a collision increases. In this case, the brake assist system from Volkswagen assists the driver by increasing braking power. The vehicle’s stopping distance can be reduced considerably as a result.

 

Based on the increased speed with which the brake pedal is actuated, the system recognises that the driver wishes to perform an emergency stop. For as long as the driver operates the brake pedal, the brake assist system increases braking pressure hydraulically via the ABS/ESP unit, up to the control range of the anti-lock brake system. When the brake pressure applied by the driver decreases, the system reduces brake pressure again to the actual level indicated by the driver. Thanks to its intelligent control strategy, the active system is hardly noticed by the driver.

Two-stage brake servo The two-stage brake servo ensures fast-action braking combined with short pedal travel, good controllability and reduced braking effort up to the point at which ABS is activated (full braking). Up to a brake pressure of about 45 bar, known as the comfort braking range, the brake servo operates with the standard factor 5 boost. This is approximately equivalent to normal braking, e.g. at a red light. If the driver brakes harder, if brake pressure exceeds 45 bar for example, brake assistance is increased to factor 10. The pedal force that has to be applied when braking is reduced significantly as a result.