Regulating car brake pressure to prevent critical wheel slippage

摘要

A first threshold value (S1) is provided for normal driving and a second threshold (S2) given for use when any one brake circuit is shown to have failed in order that this second value should enable the wheel to apply greater force to the road in the wheel travel sense. In one circuit the brakes serve the front axle wheels and the rear wheels in the second circuit. The first value (S1) is rated to ensure the wheels obtain sufficient lateral guidance even on low-friction roads. Thus, in the case of the optimal frictional connection between wheel and road then this second threshold value (S2) is used to retard the vehicle. Brake circuit dysfunction can be notified by redundant comparison-based controls or by direct sensors or again by a direct wheel travel speed contrast between wheels served by the two circuits.