What is the anti-lock brake system (ABS); Its working principle and various components (with PDF and FAQ) | learn mechanics (2023)

An anti-lock braking system is a system used to prevent the wheels from skidding under hard braking.

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In general, vehicles without ABS lock the wheels as soon as the driver applies the brake and presses the brake pedal. Therefore, the wheels slide on the road. In this case, if a large rock suddenly appears in front of the vehicle when the driver presses the brake pedal, the wheels will slip and the driver will lose control of the vehicle.

What is the anti-lock brake system (ABS); Its working principle and various components (with PDF and FAQ) | learn mechanics (1)

Thus, the driver with ABS can easily brake the vehicle and even change the direction of the vehicle if a large rock suddenly appears in front of the vehicle. Simply put, ABS prevents your vehicle's wheels from locking at all times and helps bring your vehicle to a stop without wheel spin.


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

working principlevonAntiblockiersystem

It works on the principles of cadence braking and limit braking. Cadence braking and limit braking are techniques in which the driver applies and releases the brakes before locking the wheels, or applies and releases the brakes before locking. This process of braking and releasing the wheels is done in a pulsating manner to prevent the vehicle from locking and skidding. Drivers practice this technique to gain better control of the vehicle by braking quickly and preventing the vehicle from skidding. The ABS system performs this braking rhythm automatically to prevent the wheels from locking or the vehicle skidding when braking.

because isAntiblockiersystemimportant?

To better understand this, consider an incident. When you are driving a car on a highway and suddenly an obstacle appears in front of you and you suddenly apply the brakes. This locks the car's wheels and causes the car to skid on the road. In addition, when skidding, you cannot hold the steering wheel and move the car in the desired direction. Eventually you will encounter this obstacle and face an accident.

Imagine a different situation. You are currently driving a car with ABS braking system. When you hit an obstacle on the road and brake suddenly. But this time, the car's ABS system prevents the wheels from locking and skidding. At this point you can control the steering to avoid the car hitting obstacles. In this way, the ABS system prevents the vehicle from skidding and provides more control over the vehicle to avoid accidents.

What components are used in an anti-lock braking system?

What is the anti-lock brake system (ABS); Its working principle and various components (with PDF and FAQ) | learn mechanics (2)

Quelle: Encyclopedia Britannica, Inc

electrical control unit

The controller used in the ABS system is of the ECU type. Its main function is to get information from each wheel speed sensor. If the wheel loses traction, a signal is sent to the controller, which limits brake force (EBD) and triggers the ABS modulator. An activated ABS modulator controls the activation and deactivation of brakes and valves and varies the pressure on the brakes.

speed sensors

Used to calculate wheel acceleration and deceleration. It consists of a gear and an electromagnetic coil or magnet and Hall Effect sensor to generate a signal. When the vehicle's wheels or differential rotate, a magnetic field is induced around the sensor. This fluctuation in the magnetic field generates a voltage at the sensor. This generated voltage sends a signal to the controller. Using voltage, the controller reads the acceleration and deceleration of the wheel.

Hydraulic control unit

A control unit that operates by receiving signals from an electronic control unit (ECU). The Hydraulic Control Unit (HCU) directs brake fluid into the input line, stopping the flow or withdrawing brake fluid from the return line to apply or release the brake depending on signals from the ECU, thereby preventing constant wheel lockup.

The HCU consists of the following components:-

i) Bomba
ii) Accumulator
iii) Solenoid valves

Pump: The pump is used to repair the tension in the hydraulic brakes after the valve releases the tension. When the controller detects wheel slip, it sends alerts to activate the valve. After the valve releases the driver-supplied voltage, it corrects a desired amount of voltage in the braking system. The controller modulates (adjusts) the popularity of the pump with the intention of delivering a preferred amount of tension and reducing wheel slip.

Accumulator: It is a workshop device used to store pressurized brake fluid. The storage outlet is connected to the solenoid valves.

Magnet valves: Solenoid valves work on the signal detected by the ECU to - supply pressurized brake fluid to use the brake to prevent brake fluid leakage to take brake fluid backflow to apply brake pressure to the wheel.

Lehrer cylinder: A device for pumping brake fluid, consisting of a piston, brake fluid and a return spring.

(Video) Anti Lock Braking System (ABS)(हिन्दी )

The piston rod is connected to the brake pedal. So when the driver steps on the brake pedal, the piston pushes brake fluid into the master cylinder.

The oil reservoir is connected to the master cylinder, which maintains the amount of oil in the system. The output of the master cylinder is connected to the hydraulic control unit.

Types of anti-lock braking systems.

Non-integrated anti-lock braking systems

Non-integrated systems include a vacuum-assisted booster and master cylinder. The control unit is also separate.

There are independent hydraulic units and pumps, motors and accumulators. A solenoid valve may be provided to control the hydraulic pressure at the wheels.

two-wheel system

These systems only have pressure regulation on the rear wheels. When braking, pressure is transmitted through the valve. The control unit monitors the speed sensor signal.

If it recognizes that the deceleration that has occurred is so great that the wheels can lock, it activates the blocking valve. This avoids pressure on the rear wheel and further deceleration. If this does not prevent a delay, the control module activates the dump valve. This continues until the wheel and vehicle decelerations are equal.

When the brake pedal is released, the control module deactivates the isolation valve. This allows fluid to flow back into the master cylinder.

The control module also controls the solenoid valves. The control module also detects system errors. Wheel speed sensors continuously provide wheel speed to the control module.


The system has four channels, one for each wheel, and the hydraulic control unit has two solenoid valves for each wheel.

Normal braking is assisted by the vacuum braking system. Another variant has three channels, one for the front wheels and one for the rear wheels.

The system has two solenoid valves on each channel. Better steering control is available with these systems.

The pressure regulation made on the four wheels allows the brakes to work very safely and bring the car to a standstill in the shortest possible way.

The ECU closes the intake solenoid valve when it detects that deceleration could cause the wheels to lock. This prevents more liquid from entering the circuit.

If the wheel is still decelerating and stalling is possible, the ECU will open the exhaust solenoid valve. After the brake is released, the control module returns the intake and exhaust solenoid valves to their original positions.

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The ECU also calculates the slip rate for each wheel using wheel speed sensors. When the slip rate is high, it sends a control signal to the modulator.


The integrated system combines the master brake cylinder, hydraulic booster and their circuitry into one unit.


When the brakes are applied, the deceleration of each wheel is monitored by the control module. If the deceleration is too high, a signal is sent to the hydraulic unit and the wheels could lock.

The hydraulic unit must initially keep the fluid pressure in the wheel constant and must not increase. If the deceleration is still large, decrease the fluid pressure.

This is achieved by the control module sending a signal to a solenoid valve which activates the hydraulic unit. This prevents the wheels from locking when braking.

On the other hand, if the braking force is insufficient, the control module sends a signal to the hydraulic unit to increase the hydraulic pressure and increase the braking force.

This control cycle is repeated many times depending on the braking requirement.

As soon as the brake pedal is released, the piston in the master cylinder returns and fluid from the booster chamber returns to the reservoir. When braking under normal conditions, the push rod actuates the lever. This moves the control valve and closes the gap between the booster chamber and the reservoir. It also partially opens the battery door. Fluid moves from the accumulator into the booster chamber under high pressure.

The fluid pushes the piston forward, increasing the thrust on the rod. If the control unit detects a wheel lock, the valve opens. The valves supply fluid to the chambers between the master cylinder pistons and between the retraction sleeve and the first master cylinder pistons.

High pressure fluid in the recoil sleeve pushes back on the push rod and brake pedal. The high pressure fluid is actually supplied by the accumulator, not by depressing the brake pedal.

Control valves also open and close solenoid valves to control wheel braking. When the solenoid valve opens, the piston in the master cylinder supplies fluid to the front wheels and the booster chamber to the rear wheels.

Closing the brake master cylinder and booster chamber shuts it down. The liquid returns from the wheel to the reservoir.

Braking takes place in corners and the anti-lock braking system should work differently in this situation.

work theFAnti-lock braking system (ABS)

The controller (ECU-Electronic Control Unit) reads the signal from the speed sensor of each wheel.

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If the driver brakes hard, the wheels will decelerate more quickly and may lock.

When the ECU reads a signal indicating a sudden drop in wheel speed, it sends a signal to the valve to close it and relieve brake pad pressure to prevent the wheels from locking.

The wheel starts accelerating again and sends the signal to the controller again. Now open the valve and increase the pressure on the pads to apply the brakes. This causes the wheel to slow down again and try to stop.

When a driver brakes hard, this braking and releasing process occurs 15 times per second. This will prevent the wheels from locking and the vehicle from skidding. Braking with the ABS system allows the driver to steer the vehicle and reduces the risk of a vehicle collision.

How do you know that theAntiblockiersystemis it working?

When the ABS is working, the driver can feel it through the pulsing of the brake pedal; This happens due to the rapid opening and closing of the valves. The pulsating action of the pedal informs the driver that the ABS system is operational. Any fault in the ABS system will be displayed on the vehicle's instrument panel and will work when the fault is fully resolved.

What are the advantages of aAntiblockiersystem?

Prevents wheels from locking and eliminates the possibility of skidding.

Vehicle skidding is completely eliminated for superior braking control.

The ABS system provides better steering control.

Reduces the chance of collision by 30%.

What disadvantagesAntiblockiersystem?

Vehicles with ABS (anti-lock braking system) are more expensive than vehicles without ABS.

frequently asked questions: Frequently Asked Questions

What is an anti-lock braking system (ABS)?

An anti-lock braking system is a vehicle safety feature that uses speed sensors to prevent the wheels from locking when the vehicle brakes. It is an essential element to prevent the car from skidding on slippery roads, which can be difficult to control.

IfAntiblockiersystemedo you work on a motorbike

On motorcycles, anti-lock braking systems prevent the wheels of a two-wheeler from locking when braking. Based on information from wheel speed sensors, the ABS unit adjusts brake fluid pressure to maintain traction during deceleration and avoid accidents.

when was the firstAntiblockiersysteminvented?

The first fully electronic anti-lock braking system was developed for Concorde aircraft in the late 1960s. The modern ABS system was invented by Mario Palazzetti (known as "Mr. ABS") at the Fiat research center and is now standard on all cars.

What is the function of the brake pump in theAntiblockiersystem?

The ABS pump is used to return pressure to the hydraulic brakes after the valve opens. The controller changes the state of the pump to produce the desired pressure and reduce slip. In a hydraulic brake fluid system, brake fluid is the primary application for the brakes.

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What is the principle of anti-lock braking system? ›

ABS operates by preventing the wheels from locking up during braking, thereby maintaining tractive contact with the road surface and allowing the driver to maintain more control over the vehicle.

What is ABS system and how it works? ›

The anti-lock braking system means the system that prevents the wheels from locking when the brakes are applied in a moving car. With ABS, as you apply the brakes, the speed sensors track the decreasing rotation of the wheels and when rotation is about to stop, they send a signal to the electric control unit (ECU).

What are the principles of ABS? ›

ABS is an electronic brake control system that works in principle like cadence braking, only it's much more effective. This advanced driving technique is useful on non-ABS equipped cars, as the driver pumps the brake pedal to regain steering control while also providing maximum braking.

What are the components of anti-lock brake system? ›

Components of an automatic braking system

ABS is made up of five major parts: an ABS speed sensor, valves, a siphon, braking fluids, and a regulator.

What are the 3 modes of ABS? ›

ABS types. There are three basic types of anti-lock braking systems: four-channel/four-sensor, three-channel/three-sensor and one-channel/one-sensor. The best option is the four-channel system because it can micromanage brake action in a skid by pulsing only the affected wheel or wheels.

What are 3 benefits of ABS braking systems? ›

Reduces halting distances on dry and some smooth surfaces on loose gravel or snow-covered surfaces. It steers out dangerous scenarios. Highly adaptable to different kinds of surfaces. Greatly lessens the chance of vehicle skidding while braking the vehicle.

What are the two main types of ABS used? ›

ABS comes in two types: two-wheel and four-wheel. Some light trucks and vans have a two-wheel anti-lock braking system on the rear wheels that maintains directional stability. Although the front wheels can still lock up, the vehicle continues to move in a straight line.

What is ABS and how does the system work quizlet? ›

What is anti-lock brake system(ABS)? Anti-lock brake system(ABS) prevents skidding and allows drivers to steer during an emergency braking situation. ABS can help improve vehicle stability, steering ability, and stopping capability.

What are the 5 major components of braking system in a modern vehicle? ›

The components of the brake system include:
  • Brake pedal - Used by driver to slow car.
  • Master cylinder - Leads network of pipes through which brake fluid flows.
  • Fluid reservoir - Stores hydraulic brake fluid.
  • Disc brakes - Consist of disc, piston and caliper with brake pads.

What is anti-lock braking system and why is it safer? ›

“An anti-lock braking system (ABS) prevents wheels from locking up and cars from skidding when the brake is harshly applied, especially on slippery road conditions, guaranteeing safer driving.”

What is anti-lock braking quizlet? ›

What is anti-lock brake system(ABS)? Anti-lock brake system(ABS) prevents skidding and allows drivers to steer during an emergency braking situation. ABS can help improve vehicle stability, steering ability, and stopping capability.

Can I drive my car with a broken ABS sensor? ›

If your ABS sensor goes bad, can you still drive your car? The answer is yes, but it's not ideal. ABS sensors are important for keeping your car stable and stopping properly in difficult conditions.

Can I drive my car when ABS light is on? ›

If your ABS light comes on individually, you are safe to drive your car to your destination, as your normal brakes will still work. You will, of course, have to be more careful as your ABS will not respond in case of an emergency.

Can you drive without ABS brakes? ›

Without ABS, a rapid, hard brake application could cause wheel lockup and loss of vehicle steering control, if the driver does not pump the brakes correctly or limit the brake pedal force to prevent wheel lockup. Therefore, more driver skill is needed to obtain short stops without ABS.”

What are the two types of ABS sensors? ›

Types of ABS Sensors

The two basic types are active and passive ABS Sensors. Active sensors need an external energy source to operate and are designed for toothed/magnetic encoder wheels. There are also two types of active sensors, Hall sensors and Magneto Resistive sensors.

What does antilock braking system ABS allow the driver to do _______________? ›

Essentially, the ABS is a system that modulates brake pressure in an emergency stop to keep the wheels from locking up. This allows the driver to maintain control of the steering wheel and stop the car as quickly as possible.

How many types of anti lock braking systems are there? ›

There are two main types of modern ABS systems: three and four channel. Three channel systems control the braking pressure on both front wheels independently, but control the rear wheels together as a single unit.


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