Credit: Chris828

Ever wondered what is orange ABS logo that lights up each time you start your car?

ABS stands for Anti-lock Braking System(ABS). It prevents the wheels from locking up. Allowing drivers to safely steer away from obstacles.

Imagine driving on an expressway and the roads are wet after rain. What do you do in a situation when you have to brake suddenly. Without the ABS, the wheels of your cars will lock up and stop spinning and the car will begin to start skidding. Once you lose control of the car, the results can be fatal.

A car without ABS does not have directional steering ability

ABS allows drivers to steer the car safely out of the obstacle without skidding towards it. Even professional drivers can’t stop as quickly without ABS as an average driver can with ABS.

How does it work?

A car with ABS allows the driver to steer away from obstacle

The modern ABS system 4 major components. Mainly the speed sensor, valves, electronic control unit and the hydraulic control unit.

Speed Sensor

The speed sensor checks the speed of each wheel and compares it to the database to ensure that it matches the characteristics of the vehicle acceleration and deceleration.


The vales regulate the air pressure provided to the brakes during the braking action. In each brake line, there is a valve that is controlled by the ABS.

First, the brake valve opens allowing the pressure from the master cylinder to be transferred to the brakes.

Next, the brake valve remains closed and the pressure from the master cylinder is limited.

Finally, the valve releases some of the pressure on the brakes. The cycle repeats until the car comes to a complete stop.

The resistance that you feel on the brake pedal is actaully the brake valves controlling the pressure that is transferred directly to the brakes from the master cylinder.

Electronic Control Unit (ECU)

The ECU receives all the data from each wheel speed sensor and computes the required braking pressure base on the database.

Hydraulic Control Unit

The Hydraulic Control Unit receives the signal from the ECU to control the application of the brakes by increasing the hydraulic pressure or bypass the brake pedal force to reduce braking power.

Seeing it in action

When a vehicle is braking and a wheel lock up is anticipated, the ECU commands the HCU to release the brake pressure. Allowing the wheel to increase it’s velocity so that it does not slip.

After the wheel increases it’s speed, the ECU reapplies brake pressure to restrict the wheel slip to a certain degree. When the braking action is initiated, the tire tends to slip which makes the speed of the vehicle different from the tire.

This difference in speed allows the ECU to determine the required brake pressure in each wheel cylinder based on the inputs from the system sensor.

As a result, this allows the speed to be controlled and the process is repeated for the next braking operation.

Current research shows that cars equipped with ABS are far less likely to be involved in multi-car accidents because they are still able to steer the car away from danger.

However, we must note that the braking distance does not reduce due to ABS and it allows the driver to steer away from danger safely.

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