Comparing Stopping Capabiity of Cars with and without Antilock Braking Systems (ABS)

The increasing adoption of Antilock Braking Systems (ABS) has focussed attention on the stopping distances which can be achieved with such systems. At the same time, the efforts to “harmonise” the European and American braking regulations have highlighted the importance of the wheel-lock sequence and its effect on stopping distances.

This paper investigates the parameters which influence the stopping distance potential of passenger cars with and without antilock control, and describes two alternative methods of analyzing the stopping capability, viz. a computer calculation program and a graphical design procedure. Examples of both methods are presented to illustrate the influence of the tire-to-road adhesion, the brake-force distribution and the antilock control on the stopping capability of typical passenger cars. Finally, a simple summary diagram enables stopping distance comparisons to be understood correctly.