What is ABS?
9 Feb 2017What is ABS?
By Hugo Griffiths from Car Buyer
Like the seatbelt, the anti-lock braking system (ABS) is one of the first safety features ever fitted to cars. It's been saving motorists' lives since the 1960s, and all mass-market cars sold in the EU since 2004 must have it, by law. But how does ABS work, and why is it so effective?
Why is ABS important?
It might sound obvious, but the only physical contact your car has with the road is through its tyres. The ‘contact patch’ between tyre and road is only roughly the size of a human hand and, if this is compromised by a loss of grip, the driver won’t have full control of the car. ABS is intended to stop the wheels from locking up and skidding during heavy braking, or when slowing in slippery conditions.
The benefits of this are twofold. Firstly, if the tyres lose grip and skid, stopping distances (as well as the likelihood and seriousness of any potential collision) vastly increase. Secondly, because a car’s wheels must be rotating for steering to be possible, if the front tyres lock up and stop spinning you won’t be able to steer around any obstacle, or direct the car along a safer path.
How does ABS work?
If you brake very heavily, suddenly or in slippery conditions, the forces exerted by the brakes can be powerful enough to cause the tyres to break traction with the road; the wheels will stop spinning and lock up, even though the car’s momentum will cause it to continue moving.
An anti-lock braking system comprises a series of sensors that monitor how fast each wheel is rotating. If these detect a wheel has suddenly stopped spinning when heavy pressure is applied to the brake pedal, the system is automatically activated to prevent the wheels from locking up.
When triggered, ABS releases and reapplies the brakes rapidly – around 15 times a second. This prevents the wheels from locking up, helping maintain grip and, consequently, control. If this happens, you’ll be able to tell fairly easily: the brake pedal will judder or pulse rapidly under your foot.
How can I tell if my ABS is working?
In a perfect world, you wouldn’t really need to know it’s there; it’s meant to be a safety net, just in case you need it. But, because ABS only really comes into play if you’re beginning to lose control of the vehicle, it’s difficult to tell whether or not it’s working in normal driving conditions. However, as long as the ABS light (similar to the main image at the top of this article) isn’t lit up, then there shouldn’t be an issue with the system.
It may flash off and on if the system activates – another warning that you’re close to the edge of grip – but it’ll go out again immediately afterwards. If, however, the light comes on and stays on, then this could mean there’s an issue with the ABS. If this happens, we recommend you take your car to a garage to get it looked at.
With the ever-greater amount of standard safety kit you get on modern cars, it’s easy to overlook the vital role that ABS has played in automotive safety over the last four decades or so. If you’d like to know more about all the systems that keep you safe on the road, read our guide to car safety for more information.
This article was written by Hugo Griffiths from Car BuyerOpens in new window and was legally licensed through the NewsCred publisher network.
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