ABS is designed to ensure drivers retain control of their car when they brake hard. But what is it and how does it work?
ABS, or the anti-lock brake system, sounds counterintuitive. Surely if you brake hard, you want the wheels to stop turning?
Well, in fact that is the last thing that should happen, as you have no longer have any control of the vehicle.
ABS is a safety feature designed to prevent your car’s wheels from seizing. With the car still moving on the same relatively small area of tyre, you’d lose traction.
This means the car would skid, regardless of where the wheels are facing.
What ABS does is prevent the wheels locking-up. This ensures you still have some control of the car.
The wheels will continue to rotate, and the car can move in whatever direction they’re facing.
The system itself was initially used back in the 1950s, where it was applied as an anti-skid solution for aircraft. It first appeared in cars two decades later thanks to Ford and Chrysler.
It’s been a standard feature on all new cars sold in the UK since 2004.
The ABS is part of the car’s electronic stability control (ESC).
The ESC also helps prevent problems such as oversteer or understeer and is linked to the engine control unit (ECU), which is effectively the car’s brain.
What the ABS does is constantly monitor the sensors on each of the car’s wheels.
If it detects a sudden and significant pressure on the brakes, the ABS intermittently relaxes the brakes to stop the wheels from locking.
This series of computer-controlled actions prevents the car from skidding, ensuring the driver retails control of the vehicle.
How effective are anti-lock brakes?
It doesn’t take a genius to conclude that if the aviation industry and car manufacturers swear by ABS, it’s probably a good thing. The fact that it’s a mandatory feature on all new cars sold indicates the faith the government and other regulators have in the system.
Here are four benefits of ABS:
Cars fitted with ABS are less likely to be involved in a fatal crash.
ABS decreases the chance of frontal collision on wet and dry roads
Cars with ABS rarely stray from the road ahead.
In an emergency, a car with ABS tends to stop in a far shorter distance than one would without ABS.
Problems with ABS
ABS works best on clean surfaces, such as a typical tarmac road. They tend to be less effective on surfaces that have loose gravel, mud or snow, which is worth remembering when driving in winter.
This is because the ABS system may interpret data from the sensors incorrectly and not respond in an optimum fashion.
So, in answer to the commonly-asked question ‘does ABS work on ice?’, the answer is ‘not to an extent that you would want to rely on it alone’.
Incidentally, the issue of loose or slippery road surfaces explains why off-road vehicles tend to switch off the ABS.
A locked wheel is likely to dig in to the road surface, effectively anchoring itself, when being raced off-road.