Anti-lock Braking System allow you to maintain steering during emergency braking.
ABS is a braking system that automatically pumps the brakes for you, preventing wheel lock-up, which in turn allows you to maintain steering under emergency braking. Before ABS, if you slammed on the brakes, your wheels would lock and you would eventually come to a screeching halt. To prevent you from skidding out of control, people were taught to pump their brakes. This prevented wheel lock up.
Today, we don’t need to pump the brakes because ABS does that for us. A typical ABS system will pump the brakes about 15 times per second, far faster than any driver.
How do anti-lock brakes work?
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.
Anti-lock brakes make a distinct noise when operating and you can feel it through the brake pedal.
ABS was not designed to reduce braking distance. It was designed to allow a driver to steer while under heavy braking. In certain situations ABS can slightly increase your braking distance.
Unlike non-ABS equipped vehicles, anti-lock brakes give you control so that you can swerve around an obstacle instead of hitting it.
How do I use ABS?
The beauty of anti-lock brakes is that it requires nothing from the driver. You just slam on the brakes and stay on them. Never pump ABS because it is already doing that for you. Pumping ABS will dramatically reduce the effectiveness of the system.
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.
Most new vehicles come equipped with anti-lock brakes as standard equipment. If you find a vehicle that doesn’t have it as standard equipment, it’s well worth the money to get it. Hopefully you’ll never have to use it but if you do it can save your life.