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What Is ABS(Anti-Lock Braking System)|How It Is Working?

Anti Lock Braking System

ABS System

What is the Anti-Lock Braking System?

To avoid skidding on a slippery road while sudden braking ABS(Anti-lock Braking System) was designed, it is available in both car and bike. With the help of ABS, the driver can maintain the balance in two-wheelers and steering control in four-wheelers.

Four main component of ABS

  • Speed sensor
  • Valves
  • Pump
  • Controller

Speed sensor

It monitors the speed of each wheel and determines the acceleration and de-acceleration of the wheels. when the vehicle wheel rotates it generates a magnetic field around the sensor. An irregular rising and falling in this magnetic field generated a voltage in the sensor. This voltage produce sends signals to the controller. The acceleration and deceleration read by the controller with the help of the voltage.


A valve is situated in each brake line which is controlled by the ABS. The valve has three position-

In position one–  The valve kept open; pressure passed right through to the break from the master cylinder.

In position two– the valve blocks the line, detach that brake from the master cylinder and This averts the pressure from rising further because the driver may push the brake pedal harder.

In position three– By the valve, the pressure from the brake is released.


After the valves have released the pump in the ABS is used to restore the pressure to the hydraulic brakes. The detection of wheel slip, a signal from the controller will release the valve. the pump is used to restore the desired amount of pressure to the braking system after the valve releases the pressure supplied from the user. The controller will adjust the pump’s status in order to provide the required amount of pressure and decrease slipping.


The controller is an ECU(Electronic control module) type unit in which it receives information from each individual wheel speed sensor. If a wheel loses grip, the signal is sent to the controller. The controller will then limit the brake force (EBD) and activate the ABS modulator which operates the braking valves on and off.

Anti Lock Braking System

ABS System


Types Of Brakes

  • Four-channel, Four-Sensor ABS

This is best abs brake system, in this type the speed sensor on all four wheels and a separate valve for all four -wheels. with this setup, the controller can checks each wheel individually to make sure that it is reaching maximum braking force.

  • Three-channel, four sensor ABS

This type mostly we found in older vehicles with four-wheel ABS. In each wheel, there is a speed sensor and a separate valve for each of the front wheels but there is only one valve for both of the rear wheels.

  • Three-channel, Three-sensor ABS

It is commonly found on pickup trucks with four-wheel ABS. it has a speed sensor and a valve for each of the front wheels along with one valve and one sensor for both rear wheels.

  • Two-channel, Four sensor ABS

It is commonly found on passenger cars from the late 80s-mid 90s, it uses a speed sensor in each wheel and for each front and rear wheels there is one control valve. if the speed sensor sense locks up at any individual wheel, the control module pulses the valve for both wheels.

  • One-channel,one-sensor ABS

This is commonly found on pickup trucks, SUVs, and vans with rear-wheel ABS.for controlling both rear wheels there is one valve and one-speed sensor, located in the rear axle. In this system, it is also possible that one of the rear wheels will lock, decreasing brake effectiveness.

How does the ABS work?

ABS unit uses speed sensors on wheels to define wheel speed, as well as sensors to define when a wheel is about to lock. The maximum braking force a vehicle is able to achieve lies at a point just prior to lockup. Due to hard braking on slippery road condition if the wheels are about to lock then ABS unit reduces the brake pressure applied by the rider in a pulsing manner so that the wheels sustained to spin. This will helps the driver to control the vehicle and slow down securely as the wheels never lock. During non-emergency braking situation a driver never notices that but can be assured that in an emergency he/she can apply full brake force.


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