Presented By:Shrishant PatilM.E. Automotive TechnologyRoll no. : 13AM014

Guided By:Prof. S V ChaitanyaHOD, Mechanical Dept

Contents

1. INTRODUCTION

2. LOCATION OF ANTI-LOCK BRAKE COMPONENTS

3. OPERATION PRINCIPLE OF ABS

4. STRUCTURE AND OPERATION OF ABS

5. TERMINOLOGY OF ABS

6. ABS AND WINTER CONDITIONS

7. FOUR TYPES ABS

8. ADVANTAGES & DISADVANTAGES OF ABS

9. DEVELOPMENT & FUTURE IMPLEMENTATION OF ABS

10. CONCLUSION

INTRODUCTION

• In the last decade there has been tremendous growth and expansion of braking system in terms of technology, design, implementation etc. In recent years, brakes have changed greatly in design

• Disc brakes, used for years for front wheel application, are fast replacing drum brakes on the rear wheel of modern cars.

• Anti-lock braking system, originally developed for aircrafts braking system, reduce wear and tear on aircrafts tyres after landing, caused by flat spot. When a driver of a vehicle hits conventional brakes hard, the wheels may lock causing the vehicle to skid, especially on wet and slippery roads.

• ABS provides the capability for shorter stopping distances and the ability to steer and to maintain control during hard braking, especially on wet and slippery surfaces.

• ABS technology now allows some system to prevent wheel spin when accelerating on wet or slippery surface. This capability is known as Traction Control .Some of these systems also provides addition control when cornering or changing.

LOCATION OF ANTI-LOCK BRAKE COMPONENTS

OPERATION PRINCIPLE OF ABS

• The basic operation principle of ABS is “limiting the pressure to any wheel which decelerates too rapidly”. This allows maximum stopping force to be applied without brake lock up (skidding). If standard brakes are applied too hard, the wheels “lock” or skid, which prevent them from giving directional control. If directional control (steering) is lost, the vehicle skids in a straight line wherever it is going. ABS allows the driver to steer during hard braking, which allows controlling the car much better.

• An Anti-lock Braking System consists of speed sensors located at each wheel and a central computer. The speed sensor measures how fast each wheel is turning, and sends that information back to the computer. The computer constantly evaluates the speed of the vehicle and the speed of the wheels. When the brake pedal is depressed and the speed of the wheel reaches or gets close to locking –up, the ABS computer will then modulate the amount of brake pressure (or “ pump” the brake )as fast as fifteen times per seconds, on that wheel.

STRUCTURE AND OPERATION OF ABS

TERMINOLOGY OF ABS

1) ABS Actuator :

The work horse of ABS system, it is the piece that actually releases the pressure in the ABS channel to modulate the brakes.

2) ABS Channel:

The channel is the hydraulic line from the ABS actuator to the wheel. ABS channel can consist of one or two wheels that will pulse /modulate when the ABS actuator performs its work.

3) ABS Sensor:

The ABS system need some way of knowing a wheel which is about to lock-up. The speed sensors, which are located at each wheel or in some cases in the differential, provide this information. It measures the speed of the wheel.

4) ABS Valves:

There is a valve in the brake line of each brake controlled by the ABS.

5) ABS Pumps:

Since the wall is able to release pressure from brakes, there has to be some way to put that pressure back. That is what the pump does; when a wall reduces the pressure in a line, the pump is there to get the pressure back up.

ABS AND WINTER CONDITIONS

• Some cars have an ABS override switch, whereby the driver could turn the system off. There are two reasons for this – one being that an experienced driver might want to eke out a bit more braking performance on a track day and the other being driving on a snow covered road. This is because snow building up in front of a locked wheel improves braking performance. Of course, with ABS this does not happen since the wheel is not locked for long enough!

FOUR TYPES of ABS1) 1 or 2 channel 2-wheel (Rear ABS):

• This ABS is usually prevalent on trucks .It consists of 2 ABS sensors on the rear wheels and one or two ABS channels to pulse the rear wheel together (1 channel) or separately (2 channel).

2) 2 channel 4- wheel Criss Cross

It consists of 4 ABS sensors (one on each wheel) and 2 ABS channels arranged in a Criss-Cross(left front & right rear, right front & left rear).When the right rear wheels lock up, the left front wheel & right rear wheel are pulsed together.

3) 3 channel 4-wheel

This is the more common ABS system in cars. It consists of 4 wheel sensors and 2 channels in the front (LF, RF) and one channel for the rear wheels .When one of the front wheels lock up, it pulses independently of the other wheels. When one of the rear wheels lock up, it is pulsed together with the other rear wheel, similar to a very fast pulling and releasing of the emergency brake.

4) 4 channel 4-wheel

It consists of 4 ABS sensors and 4 ABS channels. All wheels pulse independently of each other.

ADVANTAGES OF ABS

1. In some situations, ABS can reduce stopping distances. This is because the system can achieve and maintain maximum braking better than many drivers can.

2. It enables to steer while the brakes are firmly applied.

3. It allows braking firmly on surfaces with different levels of grips.

4. It can review and adjust the driver’s driving.

DISADVANTAGES

1. Drivers may take more risks when driving vehicles fitted with ABS .

2. In exceptional circumstances, some drivers have the skill to stop in a shorter distance than that achieved by an ABS-equipped vehicle .

3. On some loose gravel surfaces and fresh snow, ABS may activate before the tyres have had a chance to “bite down” into the true road surface. In this case, braking distance for an ABS equipped vehicle may be better than a non-ABS vehicle.

4. People, who are inexperienced in using ABS, may respond inappropriately when they activate the system.

DEVELOPMENT & FUTURE IMPLEMENTATION OF ABS

1)TRACTION CONTROL SYSTEM (TCS) A series of solenoid-driven valves, and a pump-motor subsystem which can be

actuated to Typical systems consist of 3-4 wheel speed sensors.2)STABILITY CONTROL SYSTEM (SCS) The design intent of stability control is to keep the vehicle going in the direction the

driver is steering the car. To do this, the brakes are applied on one wheel to help steer the car in the correct direction.

3)ELECTRO STABILITY PROGRAM (ESP) An electro-mechanical control system designed to monitor and influence wheel

dynamics, and ultimately vehicle dynamics during any vehicle state (braking, accelerating, or coasting).

4)ELECTRONIC BRAKE FORCE DISTRIBUTION (EBD) The EBD utilizes the ABS hardware to function as an "intelligent brake

proportioning valve.

CONCLUSION

• Braking System is responsible for bring a vehicle to a complete halt. The traditional disc and drum brakes have now been replaced by ant-lock braking system .The advent of Traction Control System and Stability Control System has provided better control on the braking of a vehicle. With the traffic norms getting stringent by the day anti-lock braking system would, one day, become mandatory on all vehicles.

REFERENCES • 1).William H. Crouse and Donald L. Anglin, Automotive

Mechanics, 10th edition,Tata Mc-Graw Hill Publishing Limited,pp: 729-748.

• 2). K. Newton, W. Steeds and T.K. Garrett, The Motor Vehicle, 11th edition ,Butterworth International Editions, pp: 730-749.

• 3).Erich J. Schulz, Diesel Equipment-I, 3rd print 1988, pp: 206-234.

• 4).The journals of Society of Automotive Engineers India (SAE India).

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