What is ABS and How Does it Work in Cars?

No ABS? Your car is prone to skidding, no kidding. And while this is happening, you lose control over your vehicle and the story is not likely to end well. Thank goodness for the anti-locking braking system and the fact that most, if not all, modern cars come fitted with it.

The ABS springs into action when sudden pressure is applied on the brakes and sensors detect that the wheels are about to lock, it keeps this from happening. Only for a moment, though, and intermittently applies brake pressure – just enough to prevent the wheels from locking, the car from skidding, and an accident from happening.

Facts About ABS

  • Reduces Stopping Distance

The impact of ABS on the brakes results in a shorter stopping distance. This greatly reduces the risk of accidents and saves lives. For this reason, every driver should be quick to have the anti-lock system checked out from time to time or when there is a warning light signalling a malfunction. Of course, you can drive with a faulty ABS but at what cost. This is not something anyone should compromise.

  • Helps the Driver Stay in Control of the Vehicle

Without ABS: Slamming on the brakes will trigger the brake pad to press against the wheel discs which will then stop the rotation of the wheels. At this point, steering the vehicle won’t be possible and can lead to an accident. With ABS: The driver still retains control of the car even while the brakes are pressed. This is because the wheels are prevented from locking and brake pressure is still being applied. 

  • ABS Reduces Risk of Collisions

When you’re making an emergency stop to avoid running into an object, the reduced stopping distance ABS offers will prevent a frontal collision. Also, while braking, the tires maintain traction on the ground which keeps the wheels from skidding and the driver still able to steer the vehicle. 

  • ABS is Not Activated Every Time

The ABS is only triggered when you press the brake pedal hard in emergencies. It is not needed when, for instance, you slow down for a turn or red light. Those conditions are different and will not lock your wheels. The anti-lock brake system only gets to work when the sensors detect the tires are about to lock. 

Components of the Anti-lock Braking System

  • Speed Sensors

All 4 components of the ABS play diverse roles to affect the anti-braking system. The Speed sensor is responsible for monitoring speed levels of each wheel. The process: As the wheels of the car rotates, a magnetic field is formed around the sensor. This magnetic field continues to fluctuate as the car is in motion and the fluctuation creates an electromotive force. This force or voltage travels to the controller which deciphers acceleration and deceleration of each wheel. ABS speed sensors comprise an electromagnetic coil and a toothed wheel.

  • Valves

Without the valves to regulate pressure supplied to the brakes, the result would be devastating. Depending on the amount of force a driver applies to the brake pedal, the valve would either step in to limit it or allow it to flow through the brake. The valve assumes 3 positions depending on the amount of pressure supplied.

The open position: Otherwise called the first position. In this case, the pressure mounted on the brake master cylinder is allowed passage directly to the brake. 

The block position: This second position of the valve limits the extra pressure that comes from pressing hard on the brake by keeping the master cylinder and brake apart.

The release position: In the third position, the valve eases the pressure on the brakes thereby keeping the wheels from locking as a result of sudden pressure.

  • Electronic Control Unit

This unit collects data or information from each wheel sensor which details rotational speed and acceleration. The moment pressure is applied to the brake and tires lose traction on the ground, the ECU will receive a signal. This signal informs the ECU to limit the brake force followed by other predetermined safety measures.

  • Hydraulic Control Unit

This is where direct action is taken on the brakes. The hydraulic unit affects the brakes by either increasing the hydraulic pressure or ignoring the pressure on the brakes.

How ABS Works (step by step)

The ABS is programmed to get into action as soon as the driver slams on the brakes, and the following happens in a second:

  • The electronic control unit, otherwise called The Controller, constantly monitors the signal provided by the sensors on each wheel. If there is no sudden exertion of pressure on the brakes, the ABS will remain unchanged.
  • As soon as the brakes are suddenly pressed hard by the driver, the wheels will decelerate very quickly and this will potentially make the wheels to lock.
  • The ECU will immediately pick up on this sudden and speedy decline in speed and send a signal to the valve which then closes to limit the pressure to the brake pad. This is the second position of the valve. At this point, the wheels will stay unlocked.
  • When the wheels pick up acceleration again, another signal is sent to the ECU and then to the valve to increase pressure on the brake pad. The brakes are applied and the wheels slow down. All of this happens repeatedly until the driver takes his foot off the pedal and danger is avoided. 


Most modern cars have the ABS as a standard feature but these cars are more expensive than models without it. After reading this piece, it should be obvious that the ABS is not just another car feature, it is a necessity. It is a safety system every driver can’t afford to ignore because it can save you from unpleasant situations. Just as it is a good idea to use winter tires during the harsh conditions of the winter season, it is best to only drive cars with ABS. If not for anything, for the fact that collisions are generally reduced by 30% with ABS.

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