Antilock Braking System

A Presentation on ANTI-LOCK BRAKING SYSTEM An Advance Braking Technology…

Presented By:-Shashank Shekhar,Mechanical Engg.-3rd yr,GIFT, BBSR.

GANDHI INSTITUTE FOR TECHNOLOGY, BHUBANESWAR

INTRODUCTION TO ABSAntilock braking systems (ABSs) are electronic

systems that monitor and control wheel slip during vehicle braking.

ABSs can improve vehicle control during braking, and reduce stopping distances on slippery road surfaces by limiting wheel slip and minimizing lockup.

Reducing wheel slip improves vehicle stability and control during braking, since stability increases as wheel slip decreases.

HISTORY OF ABS… ABS was first developed for AirCrafts in1929 by French Automobile & Aircraft Pioneer Gabriel Voisin.

The German Companies BOSCH & Mercedes-Benz pioneered the first electronic version for use on Mercedes-Benz Cars in1936.

In 1960 A fully mechanical system used in the Ferguson P99 racing car, the Jensen FF and the Ford Zodiac, but saw no further use; the system proved expensive and, in automobile use, somewhat unreliable.

In 1975 Ford also introduced ABS on the Lincoln Continental Mark III and the Ford LTD station wagon, called “Sure Trak”.

HISTORY OF ABS Contd… In 1978 Bosch And Mercedes-Benz Introduced the first completely Electronic 4-Wheel Multi-Channel ABS system in trucks and the Mercedes-Benz S-Class.

In 1988 BMW became the world's first motorcycle manufacturer to introduce an electronic/hydraulic ABS system, this on their BMW K100.

In 1992 Honda launched its first ABS system  this on the ST1100 Pan European.

Comparison…Wheel lockup during

braking causes skidding which in turn cause a loss of traction and vehicle control.

This reduces the steering ability to change direction. So the car slides out of control.

With ABS system, the driver can brake hard, take the evasive action and still be in control of the vehicle in any road condition at any speed and under any load.

WORKING PRINCIPLE OF ABS system consists of a central (ECU) Electronic

Control Unit and four wheel speed sensors connected to each wheel and two hydraulic valves.

There is a valve in the brake line of each brake controlled by the ABS.the valve has three positions:

1st- The valve is open; pressure from the  master cylinder is passed right through to the brake. 2nd- The valve blocks the line, isolating that brake from the master cylinder.

III. In position three, the valve releases some of the pressure from the brake. When the ECU finds that any wheel is turning

faster than the other wheel, automatically brake hydraulic pressure to the affected wheel is increased by the ABS system so that braking force is reapplied and the wheel slows down.

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.

WORKING PRINCIPLE OF ABS Contd…

ABS components

ABS Components Hydraulic Components:- 1.Accumulator:-

It is used to store hydraulic fluid to maintain high pressure.2.Antilock hydraulic control valve assembly :-

It controls the release and application of the brake system pressure.3.Booster pump:-

It is used to provide pressurized hydraulic fluid.4.Booster/Master cylinder assembly:-

It is needed to modulate hydraulic pressure in the wheel circuit.

5.Fluid accumulator:-It temporarily stores brake fluid that is

removed from the wheel brake.6.Main Valve:-

This is a two position valve and is open only in the ABS mode.7.Modulator unit:-

It controls the flow of pressurized brake fluid to the individual wheel circuits.8.Solenoid valves:-

It is located in the modulator unit and are electrically operated by signals from the control module.

Electrical / Electronic components

1.ABS control module:-It monitors system operation and controls antilock function when needed.2.Brake pedal sensor:-Its function is to switch on the brake lights to alert other vehicles that the car is slowing down and/or is going to stop.3.Wheel speed sensor:-These are generally used for sensing the wheel speed.

Types Of Anti-Lock Braking System Four channel, four sensor ABS:- This is the best

scheme, there is speed sensor and a separate valve for all the four wheels.

Three channel, three sensor ABS:- This scheme is commonly found on pick up trucks with four wheels ABS, has a speed sensor and a valve for each of the front wheels, with one for both rear wheels.

One channel, one sensor ABS:- it has one valve ,which controls both rear wheels , and one speed sensor, located in the rear axle.

FEATURES AND BENEFITS OF ABS Features

Benefits

Control of steering

Fail-safe electrical/electronic system

Traction control

ABS Indicator Lamp

Increases steering ability and vehicle stability during braking

If the electrical/electronic system fails, the ABS is shut off

It is an optional feature that controls excessive wheel spin during acceleration

Informs the driver or technician that an ABS fault has occured

ADVANTAGES… It allows the driver to maintain directional

stability and control over steering during braking.

Safe and effective. Automatically changes the brake fluid pressure

at each wheel to maintain optimum brake performance.

ABS absorbs the unwanted turbulence shock waves and modulates the pulses thus permitting the wheel to continue turning.

DISADVANTAGES… It is very costly. Maintenance cost of a car equipped with

ABS is more.

CONCLUSIONStatistics show that approximately 40 % of

automobile accidents are due to skidding. These problems commonly occur on vehicle

with conventional brake system which can be avoided by adding devices called ABS.

If there is an ABS failure, the system will revert to normal brake operation. Normally the ABS warning light will turn on and let the driver know there is a fault.

REFERENCES…

1.www.Google.com2.www.Images.google.com3.www.Wikipedia.org4.Antilock Brakes, Traction, and Stability

Control.(chapter 59) Delmar cengage learning, 2012.

5.www.Slideshare.net6.www.autorepair.about.com/od/glossary/a/

def_ABS.htm

QUESTIONS??