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ABS Presentation1

The document introduces anti-lock braking systems (ABS). ABS prevents wheels from locking up under heavy braking through the use of electronic sensors and hydraulic valves. It helps drivers maintain control of their vehicle on slippery surfaces. ABS monitors wheel speed and modulates brake pressure to each wheel individually to prevent skidding. When extreme braking is detected, ABS pulses the brakes faster than the driver can to keep tires rolling and steerability intact. Most modern cars, performance vehicles, commercial vehicles, and some motorcycles have ABS.

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Enoch Mwesigwa
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146 views11 pages

ABS Presentation1

The document introduces anti-lock braking systems (ABS). ABS prevents wheels from locking up under heavy braking through the use of electronic sensors and hydraulic valves. It helps drivers maintain control of their vehicle on slippery surfaces. ABS monitors wheel speed and modulates brake pressure to each wheel individually to prevent skidding. When extreme braking is detected, ABS pulses the brakes faster than the driver can to keep tires rolling and steerability intact. Most modern cars, performance vehicles, commercial vehicles, and some motorcycles have ABS.

Uploaded by

Enoch Mwesigwa
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PPT, PDF, TXT or read online on Scribd
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An introduction to A.B.S.

A.B.S. --- What is it?


 A.B.S. = Anti-lock Braking System.
 A form of braking system, designed to stop the
vehicle’s wheels locking up under extreme
braking conditions.
 Examples of ‘extreme conditions’:
 Emergency braking.
 Snow, ice or water covered road.
 Gravel, grit, leaves or sand.
 Road surface contaminated with oil, diesel, etc.
Why do we need it?
 To help maintain control of vehicle under
adverse conditions.
 To reduce accidents.
Which vehicles have A.B.S?
• Most modern cars.
• Virtually all high performance cars.
• Many coaches and other P.S.Vs.
• Newer H.G.Vs.
• Some motorcycles/scooters.
• No bicycles or prams!
What are the A.B.S. major components?

 Modulator/valve assembly: works


with ABS pump and ECU to control brake
fluid pressure to individual wheels

ABS pump: used to restore brake fluid


pressure after modulator/valve assembly
has released the fluid pressure to
wheel(s).
More ABS components!
 E.C.U. (electronic control unit): senses
when each wheel speed, and when the
wheel is locked or about to lock (depending
on system). It also controls opening/closing
of the valves in the modulator/valve
assembly, often fitted to the valve body.

 The wheel speed sensor (usually inductive) has a


magnet with a winding, which works in conjunction
with a reluctor (toothed ring) which is fitted to the
hub & turns at wheel speed. This produces a square
wave signal which is sent to the ECU.
The whole picture!
 Below is shown a simple schematic of a typical 4-channel ABS.
 In this type, the pump and modulator/valve units are integrated

 What do you think makes a 4-channel system?


The BIG picture!
 This schematic shows component interconnections
What’s happening?
Scenario: Icy road, driver braked too hard!
1. Wheel sensors send signal to ABS ECU
2. ECU compares each wheel speed (counts pulses)
3. ECU decides which wheel(s) are locked/locking
4. ECU tells modulator to open/close valves to reduce brake fluid
pressure to required wheel(s)
5. Locked/locking wheel(s) start to rotate, sending signals back to
ECU
6. Pump supplies pressurised fluid to those modulated brakes
7. Cycle continues until ECU decides all wheels are not losing
traction (by about 10/20%). Normal system restored. EASY!
Let’s see some action!
 http://www.youtube.com/watch?feature=
player_embedded&v=XxQYNEq_h_M
Think it’s all over?

• Now answer these questions:


1. What is ABS?

2. What does it do?

3. Name 3 major ABS components

4. Briefly, how does it work?

Professor Severe says:


5. How many did you get right? Congratulations!

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