What your Anti-Lock Breaking System (abs) EXPLAINED

I have always noticed that many people who drive cars especially the latest models don’t know the meaning of the ABS light that comes on in the dash board. I usually ask a driver randomly to tell me or explain to me what ABS means and believe me none of them was able to tell me what that light meant. Weird, right?

Very many people drive these cars fitted with such new technology like the anti-lock braking system but don’t know how or what it is or even know how it works! By you knowing how such systems in your car operate helps you reduce on maintenance costs and not to mention avoid fatal accidents that might occur due failure of these systems.

What ABS really means, let’s explain

An anti-lock braking system (ABS) is an automobile safety system that allows the wheels on a motor vehicle to maintain tractive contact with the road surface according to driver inputs while braking, preventing the wheels from locking up (ceasing rotation) and avoiding uncontrolled skidding.

It is an automated system that uses the principles of threshold and cadence braking which were practiced by skillful drivers with previous generation braking systems. It does this at a much faster rate and with better control than a driver could manage.
ABS generally offers improved vehicle control and decreases stopping distances on dry and slippery surfaces; however, on loose gravel or snow-covered surfaces, ABS can significantly increase braking distance, although still improving vehicle control.

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The different names that your car ABS could have

Since initial widespread use in production cars, anti-lock braking systems have been improved considerably. Recent versions not only prevent wheel lock under braking, but also electronically control the front-to-rear brake bias. This function, depending on its specific capabilities and implementation, is known as electronic brake force distribution (EBD), traction control system, emergency brake assist, or electronic stability control (ESC).

How you can to tell that your car has ABS

There are two ways to tell whether you have ABS brakes. There will be a light on your dash when you start your car up and then it goes out and if you brake really hard you will feel a pulsation from the brake pedal.

If the light is permanently on the dash that means there is a problem with one of the sensors and should be looked at. Your brakes still work but your ABS is not.

How your ABS really works when driving

ABS allows you to brake and steer at the same time, provided you look where you want to go! It allows you to do this by pulsating the brakes. Essentially it is locking and unlocking the brakes therefore helping the tires to rotate rather than locking up like in the “old” days.

How ABS differs from your ordinary car breaking system

Conventional hydraulic brakes work by using a cylinder (actuator), which squeezes brake calipers together around the wheel's rotor when the brake petal is depressed.

Difficulties arise with these conventional brakes if the road is slick and the driver executes a panic stop. Under these conditions the wheels may lock up and the tires run the risk of losing their grip. When tires lose their grip of the road, there is a good chance that the car may go into an uncontrolled spin. This is why drivers in older vehicles have been taught in the past to pump brakes when on highly slippery roads.

How does the ABS operation coordinated when you're driving?

The anti-lock brake controller is also known as the CAB (Controller Anti-lock Brake).

Typically ABS includes a central electronic control unit (ECU), four wheel speed sensors, and at least two hydraulic valves within the brake hydraulics. The ECU constantly monitors the rotational speed of each wheel; if it detects a wheel rotating significantly slower than the others, a condition indicative of impending wheel lock, it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel; the wheel then turns faster.

Conversely, if the ECU detects a wheel turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied, slowing down the wheel. This process is repeated continuously and can be detected by the driver via brake pedal pulsation. Some anti-lock systems can apply or release braking pressure 15 times per second. Because of this, the wheels of cars equipped with ABS are practically impossible to lock even during panic braking in extreme conditions.

The ECU is programmed to disregard differences in wheel rotative speed below a critical threshold, because when the car is turning, the two wheels towards the center of the curve turn slower than the outer two. For this same reason, a differential is used in virtually all road going vehicles.

How to detect faults in your ABS

If a fault develops in any part of the ABS, a warning light will usually be illuminated on the vehicle instrument panel, and the ABS will be disabled until the fault is rectified.

Modern ABS applies individual brake pressure to all four wheels through a control system of hub-mounted sensors and a dedicated micro-controller. ABS is offered or comes standard on most road vehicles produced today and is the foundation for electronic stability control systems, which are rapidly increasing in popularity due to the vast reduction in price of vehicle electronics over the years.

So, where else is ABS being applied?

Modern electronic stability control systems are an evolution of the ABS concept. Here, a minimum of two additional sensors are added to help the system work: these are a steering wheel angle sensor, and a gyroscopic sensor.

The theory of operation is simple: when the gyroscopic sensor detects that the direction taken by the car does not coincide with what the steering wheel sensor reports, the ESC software will brake the necessary individual wheel(s) (up to three with the most sophisticated systems), so that the vehicle goes the way the driver intends. The steering wheel sensor also helps in the operation of Cornering Brake Control (CBC), since this will tell the ABS that wheels on the inside of the curve should brake more than wheels on the outside, and by how much.

ABS equipment may also be used to implement a traction control system (TCS) on acceleration of the vehicle. If, when accelerating, the tire loses traction, the ABS controller can detect the situation and take suitable action so that traction is regained.

More sophisticated versions of this can also control throttle levels and brakes simultaneously.
The speed sensors of ABS are sometimes used in indirect tire pressure monitoring system (TPMS), which can detect under-inflation of tire(s) by difference in rotational speed of wheels.

So, how effective is your Car with ABS on African Roads

Research has shown that on high-traction surfaces such as bitumen, or concrete, many (though not all) ABS-equipped cars are able to attain braking distances better (i.e. shorter) than those that would be possible without the benefit of ABS.

In real world conditions, even an alert and experienced driver without ABS would find it difficult to match or improve on the performance of a typical driver with a modern Anti-lock Braking System-equipped vehicle. ABS reduces chances of crashing, and/or the severity of impact. The recommended technique for non-expert drivers in an ABS-equipped car, in a typical full-braking emergency, is to press the brake pedal as firmly as possible and, where appropriate, to steer around obstructions. In such situations, ABS will significantly reduce the chances of a skid and subsequent loss of control.

In gravel and sand, ABS tends to increase braking distances. On these surfaces, locked wheels dig in and stop the vehicle more quickly. ABS prevents this from occurring. Some ABS calibrations reduce this problem by slowing the cycling time, thus letting the wheels repeatedly briefly lock and unlock.

Some vehicle manufacturers provide an "off-road" button to turn ABS function off. The primary benefit of ABS on such surfaces is to increase the ability of the driver to maintain control of the car rather than go into a skid, though loss of control remains more likely on soft surfaces such as gravel or on slippery surfaces such as snow or ice.

On a very slippery surface such as sheet ice or gravel, it is possible to lock multiple wheels at once, and this can defeat ABS (which relies on comparing all four wheels and detecting individual wheels skidding). Availability of ABS relieves most drivers from learning threshold braking.

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