The anti-lock braking system, or ABS system, is a safety system which prevents the wheels on a vehicle from locking up in a panic stop braking condition, or if you are on a slick surface.
The theory behind ABS brakes is simple. A skidding wheel has less traction than a non-skidding wheel. By keeping the wheels from skidding when you slow down, ABS brakes benefit you in two ways, you will stop faster and you will be able to steer while stopping.
There are four main components to an ABS system; the speeds sensors, the pump, the valves and the controller. The speeds sensors are located either at each wheel or in the differential, they provide the information that the wheel is about to lock up. The valves are located in each line at the brakes and they pass thru, stop and release the brake fluid from the master cylinder to activate the ABS system. The controller is the computer in the car. It watches the speed sensors and controls the valves.
When the ABS is at work you will feel a pulsing in the brake pedal, which comes from the rapid opening and closing of the valves. Some ABS systems can cycle up to 15 times per second. This equates to 60 up to 100 times of pumping action per wheel revolution.
Antilock brakes when used properly really do help you stop better. They prevent wheels from locking up and provide the shortest stopping distance on slippery surfaces. Properly operating the brakes is a definite factor though, you should not pump the brake pedal on a car with ABS. The ABS controller has the valves open and close while the pump adds pressure so that the brake pedal pumps for you.
There is really no maintenance or service that is needed with the ABS system. When the ABS light illuminates on your dash the ABS system has been disabled because there is an error in the system. We recommend having that diagnosed and repaired if that light comes on.
Being able to stop and steer your vehicle in a slippery or skidding situation is the main benefit of the ABS system.
Steve and Karen Johnston are owners of All About Automotive, providing auto repair and auto maintenance in Historic Downtown Gresham. If you have questions or comments, call them at 503-465-2926 or email them at [email protected].