Also known as ABS anti-lock braking system), this article will only give a brief overview of how it works. We will not go into too much details and will not use technical jargon.
In order the understand how ABS works, you need to understand how your cars brakes actually function, read the article How do brakes work.
Contrary to popular belief ABS brakes will not stop your car faster.
It will however, stop the wheels of the car locking up.
If your wheels lock during heavy braking and you start to skid, your stopping distance will be more than if you had braked less aggressively and did not skid.
ABS brakes 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.
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 the valves 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.
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.
Now watch this video, it really does show how worthwhile it is to get a car with ABS ;