Anti Lock Braking System (ABS): Definition, Principle, Diagram, Construction, Working, Advantages, Applications [with Pdf]

What is anti-lock braking system (abs)?

  • Anti lock Braking System is system which is used to avoid skidding of wheel by Rapid Braking action.
  • Generally, When Driver press the Brake Pedal,‌ Due to Braking, Wheel gets lock. Hence Wheel skidds on the Road.
  • Without ABS, If Suddenly Big Rock comes in front of vehicle, Driver Press the Brake Pedal & Then Due to Skidding of Wheel, Driver losts control over the Vehicle.
  • By ABS, If Suddenly Big Rock comes in front of vehicle, Then with ABS, Driver Can Easily Reduce the Vehicle Speed and Also Change the Direction of Vehicle.
  • In Easy Language, ABC helps to Stop Constant locking of vehicle wheel, Hence Results in Vehicle stops without the skidding of wheel.

Anti-lock braking system diagram:

Anti Lock Braking System


ABS System Consists of the following Components:-

  1. Master cylinder
  2. Hydraulic control unit
  3. Electronic control unit (ECU)
  4. Tooth wheel & speed sensor

1) Master cylinder:- It is Device which is used to Pump the Brake Fluid & It is consists of Piston, Brake Fluid, Return spring.

The Piston Rod is Connected to the Brake Pedal Hence When Driver press the Brake Pedal, Piston Presses the Brake fluid inside the Master Cylinder.

Oil Reservoir is Connected to the Master Cylinder, which maintains the oil quantity inside system.   Outlet of the Master Cylinder is Connected to the hydraulic Control Unit.

2) Hydraulic control unit (HCU):-  It is a Control Unit which Works as per Signals receives from Electronic Control Unit (ECU) to Apply or Release the Brake to Prevents Wheel from Constant locking During Braking.

HCU Consists of the following components:-

  • i) Pump
  • ii) Accumulator
  • iii) Solenoid Valves

i) Pump :- Inlet of pump is Connected to the Master Cylinder & Outlet is Connected to the Accumulator. Pump pressurises the Brake Fluid Receives from the Master Cylinder & Sends to the Accumulator.

ii) Accumulator :- It is a storage device, which is used to store the Pressurise Brake Fluid. The outlet of the Accumulator is Connected to the Solenoid Valves.

iii) Solenoid valves :- Solenoid Valves works as per Signal receives from the ECU to –  i) Supply Pressurise Brake Fluid to Apply Brake ii) Stop supply of Brake Fluid iii) Return flow of Brake Fluid to Release Brake Force on Wheel.

3) Electronic control unit (ECU) :- It is Control Unit, Which receives signals from Components & Sends Signals to Components to Perform Operation.

ECU Connected to the Speed Sensor, Pump, Master Cylinder.

4) Tooth wheel & speed sensor :-  This Devices helps to ECU to know about the Wheel Speed.   Tooth wheel is Connected to the Wheel & Rotates with Wheel.

Speed Sensor is also located behind the tooth wheel. It senses the Rotation of tooth wheel & Sends signal to the ECV.

How does anti lock braking system (abs) work?

Anti-lock Braking System works in the Following Steps:-

STEP-1:- When Driver press the Brake Pedal, Piston presses the Brake Fluid & Then ECU Sends signal to Solenoid Valve & Pump.


STEP-2:- When Wheel stops due to Brake, Speed Sensor sends signal to ECU. ECU Sends signal to Pump & Solenoid Valve to Stop Brake Fluid flow & Release Pressure on Wheel (By Return the Brake Fluid through the Return line).

WHEEL DRUM-> SOLENOID VALVE -> ACCUMULATOR   Therefore Wheel again starts to Rotate.

STEP-3:- Again Speed Sensor sends Signal to the ECU about wheel Speed. Again ECU Sends signal to Solenoid Valve & Pump to Start Flow , Hence Again Brake Fluid flows from –   PUMP -> ACCUMULATOR -> SOLENOID VALVE -> WHEEL DRUM

This Steps occurs Rapidly till Vehicle Speed Reduces or Vehicle Stops Without Skidding.

Advantages of anti-lock braking system:

The advantages of using the Anti Lock Braking System are as follows:

  1. Less Braking Distance
  2. Steering Control, So vehicle can turn in Desired Direction
  3. Avoids Accidents


The Anti Lock Braking System has the following applications:

  1. Bike
  2. Car

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