ABS – or anti-lock braking system – has been a mandatory safety feature on cars for over a decade, but what is ABS and how does it work?
How does ABS work?
On cars without ABS, slamming on the brakes in the event of an emergency can cause the wheels to ‘lock’ and the car to skid. The force the brakes apply to a car’s wheels under emergency braking can be greater than tyres’ grip on the road, so if the brakes are applied too suddenly – or if conditions are very wet and slippery – the tyres can skid along the surface of the road, instead of gripping it as they’re designed to. A car that loses grip with the road is technically out of control, and if this happens you won’t be able to steer properly, either.
Professional racing drivers have long practised something called ‘cadence braking’ in emergency-stop scenarios and when conditions are slippery. Cadence braking involves quickly and repeatedly ‘pumping’ the brake pedal, applying and releasing the brakes rapidly. This allows the tyres to regain grip on the tarmac and also makes steering more effective.
Anti-lock brakes work on the same principle, but they release and re-apply the brakes much faster. Clever electronic sensors monitor each wheel individually and – if they detect a wheel is close to ‘locking up’ and losing grip – they apply and release the brakes on that wheel (and any other wheel that needs it) up to 15 times a second – much faster than a human could.
How can I tell if my ABS is working?
Because anti-lock braking systems only come into play when your car loses grip, you can’t tell they’re working by pressing the brake in normal conditions. There’s no need to worry, though: if there’s any problem with your ABS, a warning light will appear on the dashboard. If this comes up, get your car checked out at a garage as soon as possible. Note that an illuminated ABS warning light will cause your car to automatically fail its MoT.
One way you’ll definitely be able to tell your car’s ABS is working is if the system activates under heavy braking or in an emergency-stop scenario. If this happens, you’ll feel the brake pedal ‘pulse’ as the brakes are released and re-applied repeatedly. This can be slightly unnerving, but you don’t need to do anything: just keep applying the brakes and let the system work as intended.
Modern cars come with more and more standard safety equipment each year. And with technological developments like autonomous braking and electronic stability control becoming increasingly popular, it’s easy to overlook the impact ABS has had over the years. One thing’s for sure, though: anti-lock-brakes are so effective that not only are they now compulsory for new cars, the principle on which they work has been helping save lives for over 40 years.