An anti-lock braking system (ABS) is a system on motor vehicles which prevents the wheels from locking while braking. The purpose of this is to allow the driver to maintain steering control under heavy braking and, in some situations, to shorten braking distances (by allowing the driver to hit the brake fully without the fear of skidding or loss of control). Disadvantages of the system include increased braking distances under certain conditions and the creation of a "false sense of security" among drivers who do not understand the operation and limitations of ABS.
Since it came into widespread use in production cars (with "version 2" in 1978), ABS has made considerable progress. Recent versions not only handle the ABS function itself (i.e. preventing wheel locking) but also traction control, brake assist, and electronic stability control, amongst others. Not only that, but its version 8.0 system now weighs less than 1.5 kilograms, compared with 6.3 kg of version 2.0 in 1978.
Anti-lock braking systems were first developed for aircraft in 1929 by the French automobile and aircraft pioneer Gabriel Voisin, as threshold braking an airplane is nearly impossible. An early system was Dunlop's Maxaret system, introduced in the 1950s and still in use on some aircraft models, in 1936 the German Companies Bosch and Mercedes-Benz pioneered the first electronic version for use on Mercedes Benz cars. This version which was made of more than 1000 analogue electronic parts was still fairly slow.
A fully mechanical system saw limited automobile use in the 1960s in the Ferguson P99 racing car, the Jensen FF and the experimental all wheel drive Ford Zodiac, but saw no further use; the system proved expensive and, in automobile use, somewhat unreliable. However, a limited form of anti-lock braking, utilizing a valve which could adjust brake pads, front to rear brake force distribution when a wheel locked, was fitted to the 1964 Austin 1800.
The first true electronic 4-wheel multi-channel ABS was co-developed by Chrysler and Bendix for the 1971 Imperial. Called Sure Brake, it was available for several years and had a satisfactory performance and reliability record. Ford also introduced anti lock brakes on the Lincoln Continental Mark III brake rotors and the Ford LTD station wagon, called Sure Trak. The German firms Bosch and Mercedes-Benz had been co-developing anti-lock braking technology since the 1930s; They first appeared in trucks and the Mercedes-Benz S-Class. ABS Systems were later introduced on other cars and motorcycles.