ABS System Parts

An anti-lock braking system (commonly known as ABS, from the German name "Antiblockiersystem" given to it by its inventors at Bosch) is a system on motor vehicles which prevents the wheels from locking while braking. more...

The purpose of this is twofold: to allow the driver to maintain steering control and to shorten braking distances (by allowing the driver to fully hit the brake without the fear for skidding or the loss of control; the system itself does not contain miracle wonder technology to improve the tire quality).

History

The German firm of Bosch had been developing anti-lock braking technology since the 1930s, but the first production cars using Bosch's electronic system became available in 1978. They first appeared in trucks and German limousines from Mercedes-Benz. ABS Systems were later introduced on motorcycles.

Anti-lock braking systems were first developed for aircraft. An early system was Dunlop's Maxaret system, introduced in the 1950s and still in use on some aircraft models. This was a fully mechanical system. It 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. The first car (worldwide) to have ABS fitted as standard (across the entire range) was the Ford Granada Mk 3 (of 1985).

Operation

The anti-lock brake controller is also known as the CAB (Controller Anti-lock Brake).

A typical ABS is composed of a central electronic unit, four speed sensors (one for each wheel), and two or more hydraulic valves on the brake circuit. The electronic unit constantly monitors the rotation speed of each wheel. When it senses that any number of wheels are rotating considerably slower than the others (a condition that will bring it to lock¹) it moves the valves to decrease the pressure on the braking circuit, effectively reducing the braking force on that wheel and causing a characteristic pulsing feel through the brake pedal.

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