This document provides an overview of anti-lock braking systems (ABS) including their construction, basic working, and advantages and disadvantages. It describes how ABS uses wheel speed sensors and electronic control units to monitor wheel speeds during braking and regulate hydraulic pressure to prevent wheel lockup, allowing the driver to steer and maintain vehicle control. While ABS provides safety benefits like reduced skidding, it also has some disadvantages such as longer stopping distances if the system malfunctions and requiring regular maintenance.

1. APracticeSchoolMid-SemesterReport
NakulPandya 2012A4PS154U

2. Introduction to ABS
Construction
Basic Working
Advantages & Disadvantages
2
Contents

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Wheel lockup during braking causes skidding which in turn cause a loss
of traction and vehicle control.
Reduces steering ability to change direction, thereby resulting in sliding
the vehicle out of control.
With an Anti-Locking Braking System ;
Allows driver to brake hard
Take evasive action
Control of vehicle under any road
condition, any speed and any load
Introduction to Anti- Locking Braking System

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Construction of Anti- Locking Braking System
A – Wheel Speed Sensors
B – ABS Control Module
C – Pressure Release Valves
D – Brake Calipers

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Working of Anti- Locking Braking System
Made up of Central Electronic Control Unit (ECU) with 4 wheel speed
sensors connected to each wheel & 2 hydraulic valves located in brake
hydraulics.
ECU regulates & monitors the rpm of all 4 wheels on a constant basis.
ABS causes valves to constantly reduce hydraulic pressure to brakes of the
lowered speed wheel, causing reduction of braking force on the affected
wheel.
Consequently, lower speed wheel starts turning faster than other three
wheels.

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Working of Anti- Locking Braking System
ECU finds that the wheel is turning faster than the others.
Brake hydraulic pressure to the affected wheel increased automatically.
Braking force reapplied and wheel slows down again.
This complete process performed by the ABS is repeated continuously
throughout the drive on mostly uneven roads and can be easily detected by
the driver of the car with the help of brake pedal pulsation.

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Working of Anti- Locking Braking System

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Advantages and Disadvantages of ABS
• Greatly reduce the possibility
of brake lock up.
• Provide better chance of
steering.
• Highly adaptable to every
surface.
• Greatly reduces the possibility
of vehicle skidding.
• Completely Electronic &
Computer controlled & hence
faster reactions to situations.
• Longer stopping distances due
to system errors.
• Delicate system, easy to harm
& damage.
• Expensive repairs & high cost
of operation.
• Requires complete overhaul
on damage of few parts.
• Requires regular check ups &
maintenance of sensors, valves
and brake fluid.

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