Here I'm discussing about ABS , why we use it, its components and working and how ECU control the vehicle with collaboration of Modulation unit , Hydraulic unit , pumps , master cylinder and wheel speed sensor. Comparison between Non ABS and ABS vehicle. Pros and corns of system using some visual clips.

1. Adnan Aslam
B.Sc Mechanical Engineering
HITEC University Taxila, Pakistan

2.  What is ABS?
 Why we need it?
 Block Diagram
 Components of ABS
 Types of ABS Systems
 How does it Works
 Comparison of ABS Vs. Non ABS Vehicle(video)
 Pros and Cons
 Conclusion

3. Antilock braking systems are electronic systems that monitor and control
wheel slip during vehicle braking.
ABSs can improve vehicle control during braking, and reduce
stopping distances.
Reducing wheel slip improves vehicle stability and control
during braking.
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http://www.a1autothreebroscarrepair.com/services.asp?service=1232

4. Under hard braking, an ideal braking system should
provide:
The shortest stopping distances on all surfaces
Maintain vehicle stability and steer-ability
 Anti-lock braking systems were developed to best
meet these needs.
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http://www.slideshare.net/haithamshehata/anti-lock-abs-show-35862387

7.  Wheel Speed Sensors (up to 4)
 Electronic Control Unit (ECU)
 Brake Master Cylinder, Hydraulic
Modulator Unit with Pump and
Valves
 Vehicle’s Physical Brakes
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http://aermech.com/anti-lock-braking-system-abs-working/

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9. It is mounted near the toothed ring.
Teeth on the sensor ring rotate past the
magnetic sensor, causing a reversal of the
magnetic field polarity, resulting in a signal
with frequency related to the angular velocity
of the axle.
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http://www.aa1car.com/library/diagnosing_abs_wheels_speed_sensors.htm

10.  The hydraulic modulator unit
contains the ABS pump as well as
solenoid valves for each brake line.
 The fifth line - far right - is from the
brake master cylinder, which is
connected to the brake pedal.
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http://www.aa1car.com/library/abs_bleeding.htm

11. The valves modulate the brake pressure up to
20 times per second, effectively realizing the
ideal tire slip percentage.
ABS ‘pumps’ the brakes much faster than
any driver could.
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http://autorepair.about.com/cs/generalinfo/l/bldef_001.htm

12. Four channel, four sensor ABS:
This is the best scheme, there is speed sensor
on all four wheels 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 valve and one sensor 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.
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13. 4 SENSORS 3 SENSORS 1 SENSOR
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14. Sensors at each of the four wheels  Sense the rotation of the wheel.
Too much brake application  Wheel stop rotating
Sensors  ECU  Releases brake line pressure  Wheel turns
again.
Then ECU applies pressure again  Stops the rotation of the wheel
releases it again and so on
 This releasing and re-application or pulsing of brake pressure
happens 20-30 times per second or more.
This keeps the wheel just at the limit before locking up and
skidding no matter
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16. It can be used for reducing the stopping
distance.
It enables to steer while the brakes are
firmly applied.
It allows braking firmly on surfaces with
different level of grips.
Safe & Effective
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17. Drivers may take more risks when driving with vehicles
fitted with ABS.
People who are inexperienced in using ABS may respond
inappropriately when they activate the system.
Maintenance of a Car equipped with ABS is required more.
Very Costly
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18.  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.
 You have to understand that ABS does not raise the speed limits of your vehicle. It only
helps you stay within the limits. ABS does not allow you to drive faster, brake later.
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