What You Should Know About ABS and Why You Need It

Anti-lock brakes are the most important active safety system available in an automobile today.

The History of ABS Like many things in the auto industry, ABS comes from the aviation industry. The first system available on cars was introduced by Bosch and equipped on the Mercedes-Benz S-Class in 1978. Over the last 2 decades, ABS has marched down market and is now available on virtually every vehicle sold in North America. Each successive generation has become more efficient and quicker to react in emergency situations.

How it works Speed sensors are located at each wheel. When these sensors 'sense' that a tire has stopped moving (the wheel is locked under braking) the sensor sends a message to the controller that in turn regulates the brake pressure to reduce lock-up. It 'pumps' the brakes over a dozen times per second by increasing brake pressure and reducing it, over and over again. Since the wheels are not locked up, a driver can swerve to avoid an obstacle while under hard braking.

Types of Anti-lock Braking Systems There are two system designs, four-wheel ABS and rear-wheel ABS. Rear-wheel systems were offered on pick-ups and some SUV's in the early and mid nineties. They only pumped the rear wheels.

Today it is difficult to find this system. Four-wheel ABS is now the mainstream. But there are two variations of four-wheel ABS. There are four-channel anti-lock braking systems and three-channel.

Both systems have speed sensors at each wheel but a three-channel system pumps the rear brakes at the same speed and the two front wheels pump individually.

A four-channel system pumps all four brakes individually as they may be on different surfaces such as ice, gravel, pavement or grass. A three-channel system is cheaper to produce and is typically offered on less expensive cars. The four-channel system is a better, more precise system, though a three channel system is still far better than no ABS at all.

The misconception ABS is not designed to reduce your vehicles braking distance. In fact depending on the road surface, it can slightly increase your braking distance. ABS is designed to give the driver full control in an emergency situation. Since the wheels won't lock, you have full control of steering so that you can avoid an obstacle. On slippery surfaces, ABS pays dividends as you can now steer away from an obstacle instead of sliding right into it.

Using ABS When ABS is automatically activated in an emergency braking situation it makes a sound and pulses through the brake pedal. This is normal. Do not pump the brakes. This will render the system useless and will cause dramatically increased braking distances. The system will do its job but you have to be confident and get on the brakes as hard as possible. Get on'em, and stay on'em!!

ABS pays for itself time and time again. Think about it. ABS costs about $500. How much does just a small fender bender cost? ABS pays for itself by helping you avoid an accident and it gives you piece of mind when driving on slippery surfaces.

Peter Johnson is the chief writer for all-about-car-selection.com. For more automotive safety information click here