What Is ABS?

10 Jan 2020 by Lisa Simm

Many people know their car has ABS but don’t know what it actually does or is for. In essence, it is an electronically controlled system which helps to stop a car’s wheels from locking up by automatically releasing the brakes fractionally.

ABS stands for anti-locking braking system. The system is designed to prevent the car’s wheels from locking up and help maintain grip under hard braking conditions. This system is important as if your wheels do lock up, you are left with virtually no control over the car’s steering and are at a high risk of skidding.

Anti-locking braking systems were first used as anti-skid systems for aircraft. It wasn’t until the 1970s that manufacturers such as Ford and Chrysler proved that it could also be used in cars. It soon started to become mainstream as the safety benefits of such a system became clear.

Since 2004, it has been a standard safety feature of all modern cars sold in Europe.

close-up of car wheel

How does it work?

The ABS is part of a cars overall stability control system, which is known as electronic stability control (ESC). The ABS specifically monitors the car wheels and will only react under heavy braking.

Each car wheel has an ABS sensor attached to it which can detect if a wheel is about to lock up and stop moving.

If the sensors detect a wheel locking, it will send a message to the engine control unit (ECU). This triggers the ECU to momentarily release the brake on that wheel. The ECU intermittently releases the brakes on each wheel, hundreds of times a second, until the wheel is no longer at risk of locking up.

When the anti-locking brake system is active, you may feel a pulsation from the brake pedal when you press it.

When are anti-lock brakes most effective?

ABS is most effective when you brake promptly and firmly. This is because ABS has been designed to kick in when the wheel has started to lock up and skid. At this point, the car cannot be steered and the driver has no control over the car.

The quick-release of the brake prevents the wheel from locking up to help you keep control of the vehicle. It stops the car from skidding and allows the driver to remain to keep control of the steering, which means the driver should still manage to avoid the obstacle that they braked for in the first instance.

However, it is also worth remembering that ABS works best on stable surfaces. Icy, snowy or gravel surfaces can reduce the effectiveness of ABS. In fact, some ardent off-roaders will purposefully switch off the ABS as it can reduce the wheels ability to grip on more rugged terrain.

close up of man with hands on steering wheel

What to do if your car doesn’t have ABS?

If your car doesn’t have ABS or your ABS is not working unexpectedly, you can mimic its function by quickly applying and releasing the brake repeatedly as quickly as you can. This is known as ‘pumping the brakes’. Bear in mind, that this is nowhere near as effective as correctly functioning ABS and that by using your brake pedal, you cannot control a specific wheel.

Benefits of ABS

  • Decreases the chances of a frontal collision on both wet and dry roads
  • Cars less likely to be involved in fatal crashes
  • Cars with ABS fitted less likely to stray from the road

Car manufacturers are now using anti-locking braking systems to help make cornering safer at quicker speeds. Using the same sensors, the car wheels detect when a car is in danger of losing control on a corner and will apply the brakes in the same quick and repetitive way to bring the car back under control.

Limitations of ABS

  • Not as effective in icy or snowy conditions or on gravel surfaces
  • Can increase stopping distances

There is a common misconception that ABS can help reduce your stopping distance, although, the opposite is true. As the car is effectively applying and releasing the brake in quick succession, it can take fractionally longer for the car to come to a stop.

close up of brakes demonstrating ABS

What if your ABS is faulty?

It is perfectly normal for your ABS light to come on when you first switch on the engine, however, if the light stays on, it indicates that there is probably a fault with your ABS. This should not be ignored as it is a vital safety feature of your car.

Don’t panic though, we’ve got you covered. You can find out more about what could be causing the problem over on our blog ‘ABS Light (What To Do When It Comes On)’.

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