Antilock Braking System: Diagram, Parts and Operation [PDF] (2023)

In this article, you will learnWhat is the anti-lock braking system?That isdiagram Parts,operation, types, advantages,midisadvantageseverything is explained with pictures.

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What is the anti-lock braking system?

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ABS are anti-lock braking systems that prevent vehicles from skidding or skidding. These systems are commonly found on aircraft and on ground vehicles such as buses,cars,motorcyclesand trucks.

ABS prevents the wheels from locking up under braking, thus maintaining traction on the road. This allows the driver to maintain greater control over the vehicle. ABS basically works on the principles of limit braking and cadence braking.

The ABS system works at a much higher speed and works much more efficiently than other systems.types of brake systems. ABS was introduced to production vehicles over a decade ago, but today it is more sophisticated and effective than ever.

In modern ABS models, the bias from front to rear can be adjusted and wheel lock is prevented. ABS comes in a variety of configurations, including Electronic Brake-force Distribution (EBFD), Traction Control System (TCS), Emergency Brake Assist (EBA), and Electronic Stability Control (ESC). Let's analyze the components of the ABS system.

(Video) ABS [Anti-lock Braking System & Components]

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Anti-Lock Brake System Parts

The following are the important parts of the anti-lock braking system:

  1. speed sensors
  2. Bomba
  3. valves
  4. controllers

Speed ​​Sensors #1

The anti-lock braking system needs to know when a wheel is about to lock up, so it uses a speed sensor. Speed ​​sensors are located at each wheel, or in some cases, in the differential. To generate a signal, these sensors use a magnet, ahall effect sensor, or a toothed wheel and a coil ofelectromagnetic energy.

#2 Valves

Every ABS controlled brake has a valve in its brake line. Some systems have three valve positions:

  • Position one has the valve open; EITHERmaster cylinderthe pressure goes directly to the brake.
  • In position two, the valve blocks the line, separating the brake from the master cylinder. As a result, if the driver presses the brake pedal harder, the pressure will no longer increase.
  • During position three, the valve releases some of the brake pressure.

#3 bomba

In ABS, the pump is used to restore pressure to the hydraulic brake after the valves are released. A signal from the controller will release the valve upon sensing wheel slip. Using thebomba, the brake system is restored to the desired pressure level after the valve releases the pressure supplied by the user.

#4 Controllers

Each wheel speed sensor sends information to the controller, which is a type of ECU unit. The controller receives a signal when a wheel loses traction. The controller will then limit the brake force (EBD) and activate the ABS modulator, which turns the brake valve on and off.

Also read:Important parts of the automobile wheel assembly and their function [PDF]

How does the anti-lock braking system work?

Antilock Braking System: Diagram, Parts and Operation [PDF] (1)

As you already know, the anti-lock brake system has four main components: speed sensor, valves, pump, and controller. The speed sensor controls the speed of rotation of the wheels. Valves allow you to lock and release pressure to the brakes.

The bombs are full ofhydraulic brakesfluid and apply pressure to the brake drums as necessary. A controller is the electronic control unit (ECU) is the brain of an ABS and uses data from sensors to determine whether or not to pump the brakes.

(Video) Understanding Anti-lock Braking System (ABS) !

Sensors located in the wheels monitor the speed of each wheel. When the sensors detect that your car's tires are locking, the ECU reads the signal from each sensor and sends it to the respective wheel valves.

The valves then automatically activate and quickly release the brake to prevent the vehicle's wheels from spinning and help maintain driver control of the vehicle. If the speed sensors detect that the speed of one of the wheels is drastically decreasing in relation to the others, the ECU sends the signal to the valves of the respective wheel to reduce brake pressure and the valves close.

After that, the wheels start accelerating again and the signal is sent to the ECU once again, which in turn sends the signal to open the valve and increase the brake pressure, thereby applying the brakes.

The cycle repeats until the application of the brakes becomes normal. Basically, ABS works in three stages:

  1. The brake pedal is depressed.
  2. While the sensor detects skidding or stalling.
  3. ABS pumps the brakes.

Also read:Disc brake vs drum brake: what is the difference?

Types of anti-lock braking systems

The following are the main types of anti-lock braking system:

  1. four channels. four-sensor ABS
  2. three channels. four-sensor ABS
  3. Three-channel, three-sensor ABS
  4. Two-channel, four-sensor ABS
  5. ABS of a channel and a sensor

#1 Four-Channel, Four-Sensor ABS

As its name suggests, this type of ABS has a four-wheel speed sensor and a separate valve at each wheel. Four-channel, four-sensor ABS is considered the best system among other types. The reason for this is that it monitors each wheel individually to ensure the highest possible braking force.

#2 Three-Channel, Four-Sensor ABS

Using this setup, all four wheels are equipped with speed sensors, and each front wheel has a separate valve. A valve was installed for both rear wheels. Due to this arrangement, they are commonly found on older vehicles.

#3 Three-channel, three-sensor ABS

This type of ABS offers both front wheels with individual valve and speed sensor. The rear wheels, however, must share a speed sensor and valve, located on therear axle. Three-channel, three-sensor ABS is widely used in four-wheel-drive trucks.

The downside to this system is that the rear wheels share a valve and a speed sensor. Both the valve and the sensor are monitored simultaneously, so both wheels must be locked for ABS to activate. The effectiveness of a brake will be reduced if only one rear wheel locks up. Also, the system is easy to recognize since there are no individual speed sensors for the rear wheels.

(Video) How Anti-Lock Brake System (ABS) Works ?

No. 4 Two-channel, four-sensor ABS

This ABS has a speed sensor on each wheel and a control valve for each front and rear wheel as a pair. If the speed sensor detects any wheel lockup, the control module pulses both valves at that end of the vehicle. Passenger cars built in the late 1980s and early 1990s often used this system.

Nº 5 ABS of a channel and a sensor

As its name suggests, this type of ABS is equipped with a valve and a speed sensor to control all four wheels. It works similar to 3-channel ABS and is usually located on the rear axle. Also, with this ABS, a rear wheel can lock up, which reduces braking effectiveness.

This system is very easy to recognize on a vehicle as there are no individual speed sensors for any of the wheels. Because one valve controls both rear wheels, single-channel ABS systems are commonly found on trucks, vans, and SUVs.

Also read:Types of differential systems in the car [understand them now]

Why is an anti-lock braking system essential in your car?

To understand the requirement for the ABS system on all vehicles, let's consider an example. If you are driving on the highway, then unexpectedly an obstacle appears in front of you and you need to hit the brakes with full force.

This locks the wheels and your car will skid on the road. When you skid, you lose steering control and are unable to steer the car in the desired direction. Eventually, you hit that obstacle and have an accident.

Antilock Braking System: Diagram, Parts and Operation [PDF] (2)

Let's look at another situation where you are driving a car equipped with an anti-lock braking system. When driving, when you encounter an obstacle on the road and suddenly apply the brakes with full force.

Now this time your car's ABS prevents the wheel from locking and prevents you from skidding. At the same time, you can drive your car properly and avoid hitting the obstacle. Thus, the ABS system prevents the vehicle from skidding, provides more control and prevents accidents.

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(Video) Brake System Components Categories


  1. The anti-lock braking system helps reduce stopping distance since the wheel does not waste skid distance.
  2. This prevents the wheel from locking and thus enables precise braking on wet gray surfaces.
  3. ABS allows the car to avoid objects, while keeping the wheels under heavy braking.
  4. As it is a safety device with a history of effectiveness, insurers usually grant specific discounts to customers who have ABS in their vehicle.
  5. The traction control system has the greatest potential in ABS.
  6. Take better advantage of brake pads and discs.


  1. The cost of ABS brakes is high as it adds to the overall cost of a vehicle.
  2. Maintenance costs are also high because the sensors on each wheel are expensive.
  3. Since the ABS system uses foot brakes, this results in inconsistent stopping distances on different surfaces in different conditions.
  4. Experienced drivers can manually brake more frequently than ABS brakes.
  5. ABS involves the use of an additional sensor and controller, making the system complex.

wrapping it

In conclusion, the anti-lock braking system (ABS) restores traction to your tires in emergency situations. In slippery and dry conditions it offers advanced vehicle control, while in loose and snowy conditions it offers better stopping distance.

Is that. Thank you for reading. I hope I have covered everything about the "Anti-lock brake system.If I missed anything, or if you have any questions, please let me know in the comments. If you liked this article, share it with your friends.

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