An Anti-lock Braking System prevents the whels from _______.

Explanation:

Anti-lock braking system (ABS):

• An anti-lock braking system (ABS) is a safety anti-skid braking system used on aircraft and on land vehicles, such as cars, motorcycles, trucks, and buses.
• ABS operates by preventing the wheels from locking up during braking, thereby maintaining tractive contact with the road surface and allowing the driver to maintain more control over the vehicle.
• ABS is an automated system that uses the principles of threshold braking and cadence braking, techniques that were once practiced by skillful drivers before ABS was widespread.
• ABS operates at a much faster rate and more effectively than most drivers could manage.
• Although ABS generally offers improved vehicle control and decreases stopping distances on dry and some slippery surfaces, on loose gravel or snow-covered surfaces ABS may significantly increase braking distance, while still improving steering control.
• Since ABS was introduced in production vehicles, such systems have become increasingly sophisticated and effective.
• Modern versions may not only prevent wheel lock under braking but may also alter the front-to-rear brake bias.
• This latter function, depending on its specific capabilities and implementation, is known variously as electronic brakeforce distribution, traction control system, emergency brake assist, or electronic stability control (ESC).
• Typically ABS includes a central electronic control unit (ECU), four-wheel speed sensors, and at least two hydraulic valves within the brake hydraulics.
• The ECU constantly monitors the rotational speed of each wheel; if it detects the wheel rotating significantly slower than the speed of the vehicle, a condition indicative of impending wheel lock, it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel.
• The wheel then turns faster.
• Conversely, if the ECU detects a wheel turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied, slowing down the wheel.
• This process is repeated continuously and can be detected by the driver via brake pedal pulsation.