Also known as ABS, this article will give a brief overview of how it works.
We will not go into too much details and will not use technical jargon.
There are also videos at the end of this page for further explanation.

If your wheels lock during heavy braking and you start to skid,
your stopping distance will be longer than if you had
braked less aggressively and did not skid.

ABS braking will let you press on the brakes hard but
will stop the wheels from locking up.

Also if you prevent skidding, your steering control will not be affected meaning
that you have more chance of steering out of danger or around an obstacle.

ABS works alongside your normal braking system.
SO if your ABS fails, you will still have normal brakes.
An ABS failure will normally trigger an amber light on your dashboard
(check your owners manual).
 

How is it done

The ABS system is typically made of the following parts ;

1. Front and rear Anti-lock sensors.
There is one situated at each wheel to sense when the wheel is about to lock.

2. Anti-lock brake control module (controller)
This is the computer controller for the system. It gives the instructions to the HCU.

3. Hydraulic Control Unit (HCU).
Made up of valves and a pump. The computer switches these valves
very quickly to adjust brake pressure to locking wheels.
The pump is there to reapply the brake pressure.

The ABS system is constantly monitoring the speed of each wheel.

In order for the ABS to provide maximum braking power,
the controller will keep the wheels very close to the point of locking up.
It does this by switching on and off the brake pressure to each wheel individually many times per second. The controller tells the valves in the HCU to open and close, thus removing and reapplying brake pressure.

This is the bumping or vibrating sensation felt through the brake pedal when braking hard in an ABS equipped car. There is nothing wrong with the brake system.

Each wheel is monitored individually so if one wheel hits a slippery spot
on the road whilst braking heavily, only that wheel will be affected by the ABS system and all the other wheels will brake normally.

When you press on the brake hard and the ABS begins to work, you will feel the brake pedal pulsing rapidly as the cars electronics adjust the force being applied to the brakes. There may also be a scrapping or buzzing
sound, just continue to brake firmly and the ABS will assist you.

View the video clips below for further explanation ;

 


 
Anti-Lock Brakes (ABS) Safety Film