Anti-lock braking system
Overview
 
An anti-lock braking system (ABS, from German: ) is a safety system that allows the wheel
Wheel
A wheel is a device that allows heavy objects to be moved easily through rotating on an axle through its center, facilitating movement or transportation while supporting a load, or performing labor in machines. Common examples found in transport applications. A wheel, together with an axle,...

s on a motor vehicle
Motor vehicle
A motor vehicle or road vehicle is a self-propelled wheeled vehicle that does not operate on rails, such as trains or trolleys. The vehicle propulsion is provided by an engine or motor, usually by an internal combustion engine, or an electric motor, or some combination of the two, such as hybrid...

 to continue interacting tractively
Traction (engineering)
Traction refers to the maximum frictional force that can be produced between surfaces without slipping.The units of traction are those of force, or if expressed as a coefficient of traction a ratio.-Traction:...

 with the road surface as directed by driver steering inputs while braking
Brake
A brake is a mechanical device which inhibits motion. Its opposite component is a clutch. The rest of this article is dedicated to various types of vehicular brakes....

, preventing the wheels from locking up (that is, ceasing rotation) and therefore avoiding skidding
Skid mark
A skid mark is the mark a tire makes when a vehicle wheel stops rolling and slides or spins on the surface of the road. More generally, any solid which moves against another can cause visible marks, and is an important aspect of trace evidence analysis in forensic science and forensic engineering...

.

An ABS generally offers improved vehicle control and decreases stopping distances on dry and slippery surfaces for many drivers; however, on loose surfaces like gravel or snow-covered pavement, an ABS can significantly increase braking distance, although still improving vehicle control.

Since initial widespread use in production cars, anti-lock braking systems have evolved considerably.
 
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