Anti-lock Braking System (ABS) – Working Principle, Main Components with Advantages and Disadvantages

What is Anti-lock Braking System?

Anti-lock braking system known as the anti-skid braking scheme (ABS) is an automotive safety system that avoids wheel locking during braking and avoids uncontrolled skidding. The contemporary abs system enables for braking steering, which in case of sudden braking provides more control over the car.

The primary benefits of using ABS in vehicles is that it offers better car control and reduces stopping distance on dry and slippery surfaces. Since the possibility of skidding is very small in ABS assembled car, it offers better control of the engine during braking. Even a skilled driver may fail to avoid the car from skidding on dry and slippery surfaces during sudden braking without an ABS scheme. With ABS scheme, however, a normal person can quickly stop the car from skidding and get better control of the steering during braking. 


Principle of Working

It operates on the threshold braking principle and the cadence braking principle. Cadence braking and threshold braking is a method in which the brakes are applied and released by a driver before the wheel is locked and then the brakes are applied and released before locking. This method of applying and releasing the brakes on the wheel is pulse-shaped to avoid the car from locking and stopping skidding. This method is practiced by the driver to accomplish better car control during instant braking and prevent the vehicle's skidding. This cadence braking is automatically performed by the ABS scheme to avoid wheel locking and car skidding when braking is applied. To better comprehend this allows us to take an event. When you drive your vehicle on a highway and suddenly there is an barrier in front of you and you use full-powered brake. This will lock your car's tires and your vehicle will begin skidding on the highway as well as losing your steering control while skidding and being unable to move the vehicle in the required direction. You're finally hitting that barrier and facing an accident.

Why Anti-lock Braking System (ABS) is essential in vehicles?

 To better comprehend this allows us to take an event. When you drive your vehicle on a highway and suddenly there is an barrier in front of you and you use full-powered brake. This will lock your car's tires and your vehicle will begin skidding on the highway as well as losing your steering control while skidding and being unable to move the vehicle in the required direction. You're finally hitting that barrier and facing an accident.

Let's take another scenario, now you're driving a vehicle with anti-lock braking system. When you meet an obstacle on the highway and apply the brakes suddenly. But this time your car's ABS system prevents the wheel from being locked and avoids skidding. You can regulate your steering at this moment and stop the barrier from hitting your vehicle. This is how the abs system prevents the car from skidding and gives it higher control and avoids accidents.

Main Components of ABS System

It has four main components
1. speed sensors
2. Valves
3. Pump
4. Controller

1. Speed Sensors



It is used to calculate the wheel's speed and deceleration. It comprises of a toothed wheel and an electromagnetic coil or a signal generating magnet and a Hall Effect sensor. When the vehicle's wheel or differentials rotate, it induces the sensor's magnetic field. The fluctuation in the sensor produces voltage in this magnetic field. The produced voltage sends the controller signals. The controller reads the wheel's speed and deceleration with the assistance of voltage.

2. Valves


Each ABS-controlled brake line has a valve. The valve operates on three positions in some systems.

  • The valve stays open in place one; and pressure passed through it from the master cylinder to the brake.
  • The valve blocks the line in place two, separating the brake from the master cylinder. And this stops the stress on the brakes from rising further. When the rider applies the brake harder, the valve works in the second place.
  • In position three, the valve releases some of the brake stress.

Valve clogging is the biggest issue in ABS. When the valve is clogged, opening, closing or changing position becomes hard for the valve. It protects the system shape from modulating the valves and regulating pressure on the brakes when the valve is in inoperable condition.

3. Pump

When the valve releases the pressure, the pump is used to return the pressure to the hydraulic brakes. When the wheel slip is detected by the controller, the valve is released by sending signals. It restores a required quantity of pressure to the braking system after the valve releases the pressure provided from the driver. The controller modulates (adjusts) the pump status to provide required pressure and decrease wheel slipping.

4. Controller



The controller used is ECU type in the ABS scheme. Its primary role is to receive data from each individual wheel speed sensor and if a wheel loses traction with the floor, a signal is sent to the controller, the controller limits the brake force (EBD) and the ABS modulator is activated. The ABS modulator activated actuates on and off the braking valves and changes the pressure on the brakes. The controller reads the signal from each of the wheel's speed sensors (ECU-Electronic Control Unit).
This makes the wheel decelerate at a quicker pace as the brakes are suddenly applied by the driver and can cause the wheel to lock.
As the ECU reads the signal indicating the fast reduction in wheel velocity, it sends a signal to the valve that closes the valve and decreases the stress on the brake pad, preventing the wheel from locking.

Working of Anti-lock Braking System (ABS)

  • The controller reads the signal from each of the wheel's speed sensors (ECU-Electronic Control Unit).
  • This makes the wheel decelerate at a quicker pace as the brakes are suddenly applied by the driver and can cause the wheel to lock.
  • As the ECU reads the signal indicating the fast reduction in wheel velocity, it sends a signal to the valve that closes the valve and decreases the stress on the brake pad, preventing the wheel from locking.
  • The wheel again starts to accelerate, again the signal sends to the controller, this time the valve is opened, the pressure on the brake pad is increased and the brakes are applied, this again reduces the wheel speed and attempts to stop it.
  • This brake application and release method occurs 15 times in a second when the brake is suddenly applied by a driver. This prevents wheel locking and eliminates the vehicle's skidding. The driver can guide the car during braking with the ABS scheme and reduce the likelihood of vehicle collision.

Advantages

  • It protects the wheel from closing and therefore eliminates the possibility of skidding. The vehicle's skidding is totally deleted, resulting in great braking command? 
  • The ABS scheme provides stronger steering power. 
  • It decreases crash chances by 30%.

Disadvantages

An ABS-equipped car (Anti-lock Braking System) is more expensive than an ABS-free car.

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