Anti-lock Braking System (ABS)

Anti-lock Braking System

Here is the complete guide about Anti-lock Braking System (ABS). Here we provide to Anti-lock Braking System working principle, different types, Advantages and Disadvantages ect.

An anti-lock braking system is a safety device designed for the automotive system to prevent the wheels from locking up under emergency or harsh braking conditions. Almost all modern vehicles including four and two-wheelers now feature the system due to the latest safety regulations.

What is Anti-lock Braking System?

Anti-lock Braking System also known as anti-skid braking system (ABS) is an vehicle protection device which prevents the locking of wheels during braking and keep away from out of control skidding. The modern abs device allows steering during braking which gives more control over the car in case of sudden braking.

The fundamental benefits of the usage of ABS device in vehicle is that it gives better control over the vehicle and decreases stopping distance on dry and slippery surfaces. Since in ABS installed vehicle the risk of skidding may be very much less and as a result it gives a better steering control during braking. Without ABS device, even a professional driver can fail to prevent the skidding of the car on dry and slippery surfaces during sudden braking. But with ABS device, a regular person can effortlessly prevent the skidding of the vehicle and get better steering control during braking.

Working principle of Anti-lock Braking System

The working of an anti-lock braking system is less complex and can be easily understood. Though a lot has been mentioned while explaining the various types and the components of the system. but live focus as I enlighten more on the way it works.

An anti-lock braking system works with the ordinary braking system as it automatically pumps them. It’s done manually through drivers in vehicles that aren’t equipped with the system, which prevents wheel lockup. In vehicles equipped with ABS, the driver’s foot should be firmly placed on the brake pedal, even as ABS pump the brake automatically. This allows the driver to concentrate on steering safely.

The actuation of the ABS causes the brake pedal to pulse noticeably as a few unexperienced drivers suppose that’s brake failure. Some system is additionally designed to monitor the rate of acceleration released or time among accelerator release and brake application. The machine will then automatically increase the braking force where enough pressure is required.

Just as earlier mentioned, the anti-force braking system monitors the wheels under heavy braking. it’s generally known as electronic stability control, which allows to achieve the monitoring. Depending at the type, every wheel has a sensor, which detects when a wheel is about to lock up and forestall moving. The machine will then launch the brake, permitting it to move. The ABS constantly follow most effective braking strain to every wheel, permitting a degree of braking to arise and now no longer to absolutely lock the wheels.

With this effect, the risk of skidding is decreased even when excessive evasive maneuvers happen. This is why the driver must know the braking distance may increase. This approach the car might not stop immediately while driving in an obstructed road.

Main Components of ABS System

It has four main components

  • speed sensors
  • Valves
  • Pump
  • Controller

Speed Sensors

It is used to calculate the acceleration and deceleration of the wheel. It consists of a toothed wheel and an electromagnetic coil or a magnet and a Hall Effect sensor to generate signal. When the wheel or differentials of the automobile rotates, it induces magnetic field around the sensor. The fluctuation on this magnetic field generates voltage in the sensor. This voltage generated sends signals to the controller. With the assist of the voltage the controller reads the acceleration and deceleration of the wheel.


Each brake line that’s controlled with the aid of using the ABS has a valve. In a number of the systems, the valve works on 3 positions.

  1. In position one, the valve stays open; and pressure from the master cylinder passed through it to the brake.
  2. In position two, the valve blocks the line and separates the brake from the master cylinder. And this prevents the in addition upward push of the pressure to the brakes. Valve operates in second position when the driver applies the brake harder.
  3. In position three, a number of the pressure from the brake is released by the valve.

The clogging of the valve is the major problem in ABS. When the valve is clogged, it will become tough for the valve to open, close or change position. When the valve is in inoperable condition, it prevents the system form modulating the valves and controlling pressure to the brakes.


Pump is used to restore the pressure to the hydraulic brakes after the valve releases the pressure. When the controller detects wheel slip, it sends signals to release the valve. After the valve releases the pressure supplied from the driver, it restore a desired amount of pressure to the braking system. The controller modulates (adjust) the status of the pump so as to provide desired amount of pressure and reduce slipping of the wheel.


The controller used in the ABS system is of ECU type. Its main function is to receives information from each individual wheel speed sensors and if a wheel loses its traction with the ground, a signal is sent to the controller, the controller than limit the brake force (EBD) and activate the ABS modulator. The activated ABS modulator actuates the braking valves on and off and varies the pressure to the brakes.

Types of anti-lock braking system

Anti-lock braking systems work with various schemes depending on the types of brake employed. Below are the types of anti-lock braking system in automotive vehicles:

Four-channel, four-sensor ABS

These types of ABS contain a speed sensor at the 4 wheels and a separate valve for all 4 wheels. This setup allows the controller to monitors each wheel individually, ensuring maximum braking force is achieved.

Three-channel, four-sensor ABS

This anti-lock braking system setup contains a speed sensor on all 4-wheel and a separate valve for every of the the front wheels. One valve is employed for each wheels on the rear. These types of ABS are used on older automobiles with 4-wheel.

Three-channel, three-sensor ABS

This system carries a speed sensor and a valve for every of the the front wheels. The rear wheels feature one valve and one sensor for each wheels. This scheme is usually observed on pickup vans with 4-wheel ABS. In this system, individual control is furnished in the front wheels, in order that most braking pressure may be obtained. The rear wheels have to start to lock up before the ABS will activate on the rear. However, the wheels are monitored together.

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In these types of anti-lock brake systems, there is a possibility that one of the rear wheels will lock during a stop. This will reduce brake effectiveness. Well, the system is easy to identify since there are no individual speed sensors for the rear wheels.

Two-channel, four-sensor ABS

This system is commonly found on passenger cars that exist from the late ’80s via the mid-90s. It works with a speed sensor at every wheel and one control valve for every of the the front and rear wheels as a pair. If any lock-up is detected via way of means of the velocity sensor in any individual wheel, the control module pulses the valve for both wheels on that end of the car.

One-channel, one-sensor ABS

This system is generally used on pickup trucks, vans, and SUVs as it consists of one valve that controls each rear wheels. It also has a one-speed sensor, located in the rear axle. Its running is just like the rear end of a three-channel system. The rear wheels are monitored together and they have to lock up before the ABS actuates. In this system, there is also a possibility that one of the rear wheels will lock, which reduces brake effectiveness. and the system is easy to identify, as there are no individual speed sensors for any of the wheels.

Why Anti-lock Braking System (ABS) is essential in vehicles?

To apprehend this in a better way lets us take an incident. When you are driving your automobile on a highway and suddenly an obstacle comes in the front of you and you apply brake with full power. This will locks wheels of your automobile and your automobile will start skidding on the road and also during skidding you lost your steering control and unable to move the automobile in desired direction in which you want. Finally you hit that obstacle and meet an accident.

Let’s us take another situation, now you are driving a car which is equipped with anti-lock braking system. When you encounter with an obstacle on the road and suddenly apply the brakes. But this time the ABS system of your car prevent the locking of the wheel and avoid skidding. At this time you can control your steering and can stops your car hitting from the obstacle. This is how the abs system prevents the skidding of the vehicle and provides greater control over it and prevents accidents.


Below are the benefits of an anti-lock braking system:

  • ABS prevent lockups and skidding, even in slippery conditions like stopping on ice, oily or wet road. The system is assured to save a life in such a condition, giving the driver perfect control of the vehicle.
  • Due to the effectiveness of the device, it’s now mandatory by law for all vehicles to feature them. This makes it easy for drivers to purchase devices that carry the system at low insurance costs.
  • Modern ABS is designed to have a traction control system, which allows all-wheel has traction on the road. This makes it easy for manufacturers to have both features done in the factory.
  • Cars or trucks feature with anti-lock brake system have higher resale value as the system continue to raise.


  • The system is delicate. it’s easy for the system to cause problems to the brakes such as disorientation of the ABS, where the vehicle is caused to shudder because of the brake sensors.
  • An anti-lock brake can be expensive to maintain depending on the car model. Sensors on each wheel can cost much to fix when they develop a fault. This is the reason why most people don’t ABS on their vehicles.
  • ABS ensures ideal braking in slippery conditions, but some users complain of inconsistent stop time. That is, the stopping distances for regular conditions are lengthened by their ABS. This is caused by an error in the system.


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