Car Safety 101: Anti-Lock Brakes

How anti-lock brakes work and why you should know about them

If you've ever felt a slight pulsation in your brake pedal on a rainy day, you may have felt your anti-lock brake system in action. The pulsation is caused by an ABS actuator rapidly activating the brakes, which can prevent a vehicle from skidding.

By helping you avoid skid conditions, ABS allows you to maintain better control over your vehicle. According to a study performed by Monash University, vehicles with ABS are 35 percent less likely to be involved in certain types of accidents than vehicles that do not have ABS.

Rear-view of a car putting on its breaks at a stoplight

Lifewire / Luyi Wang

How Do Anti-Lock Brakes Work?

Anti-lock brakes work by sensing the motion of each wheel. If you depress the brake pedal and the wheel sensors detect a skid condition, the ABS jumps into action.

You may have been taught to pump the brake pedal in a panic stop situation, and that is what ABS actuators are designed to do. These actuators are capable of pulsing the brakes hundreds of times per second, which is much faster than pumping the brake pedal manually.

What Is the Point of Anti-Lock Brakes?

The main point of ABS is to help you maintain control of your vehicle during panic stops and other adverse driving conditions. By rapidly pulsing the brakes, an anti-lock braking system prevents the wheels from locking in place. This allows the tires to retain traction, which can prevent a vehicle from entering a skid.

A skid is what happens when a vehicle loses traction because the locked-up wheels are able to slide freely over the surface of a road. It can be exceedingly difficult to retain control of a vehicle under those conditions. In the worst-case scenario, a skidding car may flip, run off the road, or strike another vehicle.

Anti-lock brakes are sometimes capable of reducing the stopping distance of a vehicle, but that is not the main purpose of ABS. If a road surface is wet or icy, a functional anti-lock brake system typically results in a reduced stopping distance.

These systems can result in a slightly increased stopping distance if the road surface is dry, and the stopping distance may be increased on loose road surfaces. That is because skidding wheels can cause a wedge of snow, gravel, or sand to build up and rob a vehicle of momentum.

How to Get the Most Out of Anti-Lock Brakes

The best way to make use of anti-lock brakes is to depress the brake pedal firmly when you need to stop. If you find yourself in a panic stop situation, you may also need to steer around obstacles. Since the point of ABS is to prevent a skid, you should be able to retain control of the vehicle.

It is also essential to be aware of road conditions. Since anti-lock braking systems can cause increased stopping distances on loose road surfaces, you may need to allow yourself more distance to stop.

What Happens When Anti-Lock Brakes Fail?

Most anti-lock brake systems are designed to switch off if any of the components fail. There are rare instances when a valve stays open, but the brakes usually continue to work normally.

If the pedal doesn't fade or sink, that typically means the vehicle is safe to drive. You will have to pump the brakes if you find yourself in a panic stop situation, so it's crucial to remain vigilant if your ABS quits working.

How Have Anti-Lock Brake Systems Changed Over the Years?

Anti-lock brake systems have evolved continuously since they were first introduced in the 1970s. The basic concept has stayed the same, but they have become more efficient.

Many anti-lock brake systems are capable of pulsing the brakes on individual wheels, which lead to the development of electronic stability control and traction control systems. These systems use ABS equipment to shift the braking power between different wheels, which can allow you to retain greater control of your vehicle in adverse driving conditions.

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