Most of us will be familiar with the term Antilock Brakes (ABS). However, many do not know much about the working and other details of this type of braking system. Below is a quick look at ABS and how they work.
Antilock Braking System
These are simply improved version of the ordinary brakes and are designed to prevent the normal brakes from locking up and skidding. These brakes are especially useful while braking hard, or while braking on slick and wet surfaces. These brakes can add a good level of safety by preventing dangerous skids, and letting the driver to have better steering control even while braking hard and trying to stop the car.
Experts say that ABS does not cut down the stopping distance, and might actually increase the distance on dry roads and pavements. However, on slick or wet roads, these brakes can reduce the braking distance by about 25%, which can be the distance between a safe stop and an accident.
There are many different varieties of antilock braking systems available these days, but one thing that all these braking systems have in common is the ability to control lockup of the wheels while braking real hard. This is important because once the wheel locks up; the vehicle will lose traction, reducing the friction between the tire and the road. This can lead to skidding of tires and the vehicle could take more time to stop.
The exception to the above situation is when the tire of the vehicle is on loose snow. While braking on snow, a locked tire will let snow build up in front of it as a small wedge and can help the vehicle to stop in a comparatively short distance. This is the reason why some vehicles are provided with an on/off switch to disable the antilock braking system while driving on snow.
The directional stability of the vehicle also depends on traction. As long as the tires of the vehicle are not skidding, it will roll in the direction that the vehicle is turning. However, if the tires are skidding, the vehicle will lose directional stability and will move out of control. ABS units will help to minimize loss of traction, and thereby, ensure directional stability and steering control of the vehicle.
In a nutshell, these braking systems are more of an add-on to the existing braking system of the vehicle. The system usually comes to play only when tractions conditions are marginal or when the driver tries to stop the vehicle suddenly by braking hard. ABS will not have any effect on normal braking or driving the rest of the time.
ABS units are also designed to be failsafe. If there are some issues or failure in the ABS control electronics of the vehicle, it will usually deactivate itself and the ABS warning light will be turned on. However, the vehicle will still have the normal braking mechanism. Disabling or deactivating the braking system will not make the car unsafe to ride, but the ABS system will not be available if needed in an emergency.
This means that you should never ignore the ABS warning light. It is especially important to take your vehicle to a good mechanic if the brake warning light is turned on as well, because it could be an indication of low brake fluid or loss of hydraulic pressure in the braking system. If you find that both the warning lights are turned on, you should take the vehicle to a mechanic right away and should not use it until the braking system is inspected and fixed.
Working of Antilock Brakes
All of the antilock braking systems control tire skid by monitoring the relative deceleration rates of the wheel while braking. If the sensors find that one of the wheels is slowing down at a faster rate when compared to the others, or a to a rate faster than how it is programmed into the control module, the ABS unit will understand that the wheel is starting to slip and skid and is in danger of locking up and losing traction. In such a situation, the antilock braking system will momentarily reduce the hydraulic pressure to the brake on the wheel that is starting to slip.
The braking system makes use of solenoid valves that are electrically operated to hold release and reengage the hydraulic pressure to the brakes. This can make a pulsating effect, which can be felt in the brake pedal while braking hard. You might also hear a chattering or buzzing noise from the hydraulic unit of the antilock braking system. The modulation of the brake pressure in the circuit reduces the load on the slipping wheel and lets the wheel to regain traction to prevent wheel lockup. The mechanism is the same as pumping the hydraulic brakes, except that ABS does the pumping automatically and at a much faster rate.