1. Autos
Send to a Friend via Email

Your suggestion is on its way!

An email with a link to:

http://cartech.about.com/od/Safety/a/Anti-Lock-Brakes.htm

was emailed to:

Thanks for sharing About.com with others!

Car Safety 101: Anti-Lock Brakes

By

ABS can prevent a skid.

When a vehicle enters a skid, it can be very difficult to control.

Photo © DavidHT
What are Anti-Lock Brakes?

If you've ever noticed a slight pulsation in your brake pedal on a rainy day, you may have felt your anti-lock brake system (ABS) 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 effectively allows you to maintain better control over your vehicle. According to one study performed by the Australian Monash University, vehicles with ABS are 35% less likely to be involved in certain types of accidents than vehicles that don't have ABS.

How Do Anti-Lock Brakes Work?

Anti-lock brakes work by sensing the motion of each wheel. If you depress your brake pedal and the wheel sensors detect a skid condition, the ABS will jump into action. You were probably taught to pump your brake pedal in a panic stop situation, and that is essentially 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 a brake pedal can be pumped 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 essentially 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 whenever 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 run off the road or strike another vehicle.

Anti-lock brakes are sometimes also 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 will typically result 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 dramatically increased on loose road surfaces. That is due to the fact that skidding wheels can cause a wedge of snow, gravel or sand to build up and rob a vehicle of momentum.

How Do I Get the Best Use Out of Anti-Lock Brakes?

The best way to make use of anti-lock brakes is to simply depress your 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 the 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 will stick open, but the brakes will 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 significantly 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 (ESC) and traction control systems (TCS). 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.

  1. About.com
  2. Autos
  3. Car Tech
  4. Safety Tech
  5. Anti-Lock Brakes

©2014 About.com. All rights reserved.