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201221 Jun

abs system

Sudden braking of a car on slippery roads can be a very challenging and nerve wrecking task. And if your wheels lock up on wet and slippery roads or during a panic stop, then you may lose traction and control, causing your vehicle to spin, leading to fatal accidents. Anti-lock Braking System (ABS) keep your wheels from locking up, so that your car maintains directional control during those sudden emergency braking.


The ABS System

The theory behind anti-lock brakes is simple - a skidding wheel has less traction than a non-skidding wheel. By keeping the wheels from skidding while you brake on a slippery and wet surface, anti-lock brakes benefit you in two ways - you will stop faster, and you will be able to steer and maintain directional control while you stop.


There are four main components to an ABS system:

Speed Sensors - The anti-lock braking system needs some way of knowing when a wheel is about to lock up. The speed sensors, which are located at each wheel, or in some cases in the differential, provide this information.

Valves - There is a valve in the brake line of each brake controlled by the ABS. On some systems, the valve has three positions: In position one, the valve is open; pressure from the master cylinder is passed right through to the brake. In position two, the valve blocks the line, isolating that brake from the master cylinder. This prevents the pressure from rising further should the driver push the brake pedal harder. And in position three, the valve releases some of the pressure from the brake.

Pump - Since the valve is able to release pressure from the brakes, there has to be some way to put that pressure back. That is what the pump does; when a valve reduces the pressure in a line, the pump is there to get the pressure back up.

Controller - The controller is a computer in the car. It watches the speed sensors and controls the valves.


ABS works along with your regular braking system by automatically pumping them. In vehicles not equipped with ABS, the driver has to manually pump the brakes to prevent wheel lockup. In vehicles equipped with ABS, your foot should remain firmly planted on the brake pedal, while ABS pumps the brakes for you so you can concentrate on steering to safety. More specifically, ABS automatically changes the brake fluid pressure at each wheel to maintain optimum brake performance just short of locking up the wheels. There is an electronic control unit that regulates the brake fluid pressure in response to changing road conditions or impending wheel lockup.


When ABS is activated, you may experience a slight vibration or a rapid pulsation of the brake pedal, almost as if the brakes are pushing back at you. At times, you will feel the pedal suddenly drop. The valves in the ABS unit may make a grinding, scraping or buzzing noise. This means your ABS is working. Continue to apply firm pressure and steer. Do not take your foot off the brake pedal.


Nowadays, a lot of vehicles offer ABS as either standard or cost option. To find out whether your car has an anti-lock braking system, and what type, read your owner’s manual. You can also check your instrument panel for a yellow ABS indicator light after you turn on the ignition. And when you buy, lease or rent a vehicle, always enquire if it comes equipped with ABS. Always, remember, when applied properly, ABS can work wonders in ensuring effective braking and safety.




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