Anti-Lock Brakes

Default

ANTI-LOCK BRAKES

Why does the data indicate that ABS fails to reduce accidents? Safety experts have determined that people do not know how to use ABS effectively when confronted with an emergency situation. Most of the driving populace learned accident-avoidance techniques before ABS was developed. Drivers learned to pump their brakes to keep the wheels from skidding, and years of experience behind the wheel has taught drivers what the pedal should feel like, in emergency as well as non-emergency situations. The brake pedal of an ABS-equipped car behaves quite differently when ABS is engaged.

Anti-lock brakes are controlled by a computer chip which senses when a wheel is locked up, or is about to lock up. When this occurs, the computer tells brake sensors to apply intermittent brake pressure, which prevents the wheel from locking. Essentially, the computer and brake sensors do exactly the same thing drivers would do if they pumped the brakes. The only difference is that the computer-controlled sensors can pump the brakes much quicker than any person can.

When ABS engages, a loud grating sound and rapid brake pedal pulsation often accompanies the pumping action. When this occurs, insurance companies and safety experts theorize, drivers assume that something has gone wrong with their brakes, and they begin to pump the pedal or simply lift off the brake pedal, which defeats the system.

Some drivers forget that ABS allows them to continue steering the car, since the front wheels aren't locked up. Often, drivers successfully avoid an obstacle in the road by yanking on the steering wheel, but to their surprise the car actually responds, and the turn of the steering wheel that avoids the obstacle in the road ends up putting the vehicle off the road, where it sometimes crashes.

Experts and insurance representatives appear to be evenly split on whether drivers or ABS engineers are to blame, according to the Arizona Republic article. Edmund's lays blame squarely on drivers who own cars with ABS systems. "Anti-lock brakes are one of the most important automotive safety advances in recent history," says Christian Wardlaw, automotive editor for Edmund Publications. "People who buy vehicles equipped with these systems need to re-educate themselves and lose those old ingrained habits. They need to go to a vacant parking lot on a wet or snowy day, and practice using ABS so they know what to expect when an emergency situation presents itself."

Volvo Cars of North America, Inc. included a press release about ABS, and the insurance industry study, in its 1996 media press kit. Titled "Don't be Mystified by ABS Brakes," the release explains the proper use of ABS. Jim Nordmann, Volvo's manager of technical services, says it will take a lot of unlearning on the part of the driving public to use anti-lock brake systems effectively. "Apply constant pressure to the brake pedal in a car with ABS... and steer around any obstacles that might be in the roadway. You want to stay on the brakes until you clear whatever obstacle is in your path."

Manufacturers of anti-lock braking systems agree. They don't believe drivers are well-educated, if at all, about the use of ABS. Several brake suppliers have formed the ABS Education Alliance in Washington, D.C. to educate drivers about the system.

What About Rear Wheel Anti-Lock?
Known as "RWAL" this system prevents the rear end from skidding, or fish-tailing out of control, by never locking up the rear wheels. Usually, the car will continue on a straight path if the front wheels are locked up.