ABS (Anti-lock Braking System)

Anti-lock braking system (ABS of the English Anti-lock Braking System) is one of the essential elements of active vehicle safety. ABS prevents wheel lock during braking. The wheel ABS is still rolls and thus prevents the loss of adhesion between wheel and road. Rolling the wheel makes it possible to maintain the stability, manageability and controllability of the vehicle in extreme situations (such as hard braking or when braking on slippery roads). Locked wheel is not transfer any lateral force and does not allow spin.

avoidance maneuver vehicles and vehicles with ABS without ABS

Principle:
The system prevents the wheels from locking during braking by automatically regulates the braking force in the stirrups to avoid locking the wheels. When blocking wheels losing grip and the vehicle would become unmanageable, it would not be allowed to drive change by turning the steering wheel.

Each wheel has a speed sensor, control unit which gives information about the speed of each wheel. If the control unit receives a signal that the wheel is blocked, briefly reduces the pressure in the brake system, thereby indicating wheel moving again. ABS wheel can release 12 - 16 × per second, and the system still provides relatively wheels turning and maneuverability of the vehicle (see note controllability wagon Kammova circle ). Under heavy braking system ABS braking force to maintain the adhesion, it occurs when the wheel lock and the subsequent release of rounds in rapid succession until the vehicle stops.

essential part of the ABS

Each wheel is equipped with an inductive encoder, the picture above the text is yellow sensor for the brake disc. The control unit gives information about the wheel. The control unit (gray box) and evaluate the situation using the control valve (brown in the upper part of the picture) or reduces brake pressure to the wheel moving again.

wheel speed sensor

History:
ABS was developed by Bosch in 1978. But history goes back even further. By the early 20th century, there were considerations about how to avoid locking the wheels under heavy braking. Bosch has already announced a 1936 patent for a "device to avoid strong braking wheels of a motor vehicle." But only with the advent of electronic engineers to develop anti-lock braking system, which was sufficiently fast and robust for use in motor vehicles. Found the first commercial application of the ABS as an optional extra Mercedes-Benz S-Class and shortly afterwards also in the BMW 7 Series

development and miniaturization of the ABS
1 - Generation; 2 - weight; 3 - number of parts, 4 - memory capacity

Bosch ABS system, however, developed further. As a result of further development of the systems ASR (protiprokluzovací system that prevents wheel spin when starting off), electronic stability program ESP . In recent years, appeared ABS with EBV (Electronic brake force distribution).

What You Did not Know:

How do you know the activity of the ABS system?
During heavy braking on the adhesion can hear intermittent braking on a wet road. Interruptions caused by its activities, ABS just, forgiving when the pressure in the brake system. This reduces the braking force and wheel is unlocked. Pedal of this activity, like kicking and braking for longer drops to the floor. Few experienced driver could balk and allow the brake pedal, it would be a mistake!

The stopping distance
On dry roads the vehicle without ABS shorter braking distances . The wet ground has already settled the differences and the icy surface of a vehicle with ABS shorter braking distances. An important advantage, however, remains above the possibility to control the vehicle during braking.

Text: John Sajdl
Photo: www.whnet.com, www.bosch.cz, archive Skoda Auto, www.musclecarclub.com
Keywords: Anti-lock Braking System, ABS, active safety, braking distance, braking, abrupt braking, ASR, ESP, EBV