The document discusses anti-lock braking systems (ABS). ABS uses sensors and computer control to prevent wheels from locking up during braking, allowing the driver to steer and maintain vehicle control. It works by rapidly pumping the brakes faster than the driver can to keep tires rolling slightly during braking. This allows for shorter stopping distances and easier steering control compared to regular brakes. The key components of ABS are speed sensors, a brake control module, and solenoid valves that regulate brake fluid pressure.

1. ANTI-LOCKANTI-LOCK
BRAKESBRAKES
ByBy
ANTI LOCK BRAKINGANTI LOCK BRAKING
SYSTEMSYSTEM
BY
UDDIPTA RANJAN SARMAH (0804104)
SYED JAVED IFTIKAR AHMED (0804113)
RITURAJ DHAR (0804116)

2. IntroductionIntroduction
 Wheel lockup during braking causes skiddingWheel lockup during braking causes skidding
which in turn cause a loss of traction andwhich in turn cause a loss of traction and
vehicle controlvehicle control
 This reduces the steering ability to changeThis reduces the steering ability to change
direction. So the car slides out of controldirection. So the car slides out of control
 With ABS system, the driver can brake hard,With ABS system, the driver can brake hard,
take the evasive action and still be in controltake the evasive action and still be in control
of the vehicle in any road condition at anyof the vehicle in any road condition at any
speed and under any load.speed and under any load.

3. Concept of ABSConcept of ABS
 AA skidding wheelskidding wheel (where the tire contact(where the tire contact
patch is sliding relative to the road) has lesspatch is sliding relative to the road) has less
tractiontraction than a non-skidding wheelthan a non-skidding wheel
 By keeping the wheels from skidding whileBy keeping the wheels from skidding while
you slow down, anti-lock brakes benefit you inyou slow down, anti-lock brakes benefit you in
two ways:two ways:
 You'll stop faster, and you'll be able to steerYou'll stop faster, and you'll be able to steer
while you stopwhile you stop

4. ComparisonComparison

5. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 Computerized ABS isComputerized ABS is
designed to keep thedesigned to keep the
wheels from locking aswheels from locking as
the brakes are applied.the brakes are applied.
 A locked wheelA locked wheel
provides very little orprovides very little or
no directional control.no directional control.

6. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 The following slides show the common ABSThe following slides show the common ABS
components.components.
 Some components are part of both theSome components are part of both the
conventional and ABS system.conventional and ABS system.

7. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 When operating a vehicle with ABS neverWhen operating a vehicle with ABS never
pump the brakes.pump the brakes.
 Doing so will make the ABS systemDoing so will make the ABS system
ineffective.ineffective.
 Always apply firm pressure.Always apply firm pressure.

8. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 Drivers may experience a pulsation in theDrivers may experience a pulsation in the
brake pedal, or pedal kick back during an ABSbrake pedal, or pedal kick back during an ABS
stop. This is normal and not to be confusedstop. This is normal and not to be confused
with a conventional brake pedal pulsationwith a conventional brake pedal pulsation

9. ANTI-LOCK BRAKESANTI-LOCK BRAKES
Anti-Lock
Brake Module
Speed
Sensor
Pressure
Valve Dump/Vent Valve
Master
Cylinder
Assembly
Anti Lock
12 V

10. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 Major components of the anti-lock brakeMajor components of the anti-lock brake
system consist of asystem consist of a
 Brake control module,Brake control module,
 Solenoid valve assembly,Solenoid valve assembly,
 Speed sensor'sSpeed sensor's
 Wiring, and the amber ABS brake warning light.Wiring, and the amber ABS brake warning light.

11. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 Brake Control ModuleBrake Control Module::
 The brake control module is a compute thatThe brake control module is a compute that
receives information from the speed sensorreceives information from the speed sensor
and compares it to the speed of other wheels.and compares it to the speed of other wheels.
 When one wheel is approaching lock-upWhen one wheel is approaching lock-up
pressure can be vented allowing the wheelpressure can be vented allowing the wheel
nearing lock-up to speed up.nearing lock-up to speed up.

12. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 If a wheel is to fast pressure can be increasedIf a wheel is to fast pressure can be increased
to slow down the wheel.to slow down the wheel.
 If both wheel are approximately the sameIf both wheel are approximately the same
speed the brake control module can enter aspeed the brake control module can enter a
pressure hold mode of operation.pressure hold mode of operation.

13. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 Solenoid Valve Assembly:Solenoid Valve Assembly:
Is a pair of valves that can:Is a pair of valves that can:
A.A. Increase pressureIncrease pressure
B.B. Hold pressure steadyHold pressure steady
C.C. Decrease pressureDecrease pressure

14. ANTI-LOCK BRAKESANTI-LOCK BRAKES
During pressure increase
mode of operation fluid is
allowed to flow through
both solenoids to the brake
caliper
Solenoid 1
Pressure increase
Solenoid 2
Pressure decrease/Vent
solenoid
Brake line under pressure
Brake fluid line not under pressure

15. ANTI-LOCK BRAKESANTI-LOCK BRAKES
During Pressure Hold
mode of operation both
solenoids are closed and
no additional fluid is
allowed to flow to brake
calipers.
Solenoid 1
Pressure increase
Solenoid 2
Pressure decrease/Vent

16. ANTI-LOCK BRAKESANTI-LOCK BRAKES
During Pressure Vent mode
the pressure increase solenoid
is closed. The Vent solenoid
opens allowing fluid to vent into
an accumulator chamber
Solenoid 1
Pressure increase
Solenoid 2
Pressure decrease/Vent

17. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 ABS system can maintain extremely highABS system can maintain extremely high
static pressure and must be disabled beforestatic pressure and must be disabled before
attempting repairs.attempting repairs.
 Normally pumping brake 20-30 times willNormally pumping brake 20-30 times will
release pressure.release pressure.

18. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 ABS brake system areABS brake system are
 IntegratedIntegrated
 NonintegratedNonintegrated

19. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 An integrated system has the master cylinderAn integrated system has the master cylinder
and control valve assembly made together.and control valve assembly made together.
 A nonintegrated has the master cylinder andA nonintegrated has the master cylinder and
control valve assembly made separate.control valve assembly made separate.

20. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 ABS operates using the same hydraulicABS operates using the same hydraulic
principal as conventional brakes.principal as conventional brakes.
 ABS system only operates when wheel lock-ABS system only operates when wheel lock-
up is emanate.up is emanate.
 A bussing noise and bakes pedal vibration isA bussing noise and bakes pedal vibration is
normal during ABS operation.normal during ABS operation.

21. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 To determine if wheelTo determine if wheel
lock-up is about tolock-up is about to
occur vehicles a wheeloccur vehicles a wheel
speed sensor.speed sensor.


22. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 There 3 ABSThere 3 ABS
configurationsconfigurations
 1. channel normally1. channel normally
RWAL (rear wheel anti-RWAL (rear wheel anti-
lock)lock)
 In a one channel RWALIn a one channel RWAL
system the rear wheelssystem the rear wheels
are controlled togetherare controlled together

23. ANTI-LOCK BRAKESANTI-LOCK BRAKES

24. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 ABS brakes are eitherABS brakes are either
 1. Channel1. Channel
 3 Channel3 Channel
 4 Channel4 Channel

25. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 1 channel ABS system controls the1 channel ABS system controls the rear wheelrear wheel
together.together.
 A 1 channel system only has 1 speed sensorA 1 channel system only has 1 speed sensor
and control valve assembly.and control valve assembly.

26. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 A three (3) channel ABS system control theA three (3) channel ABS system control the
rear wheel togetherrear wheel together and theand the frontfront
independentlyindependently..
 Three channel ABS system haveThree channel ABS system have 3 speed3 speed
sensor and one (1) control modulesensor and one (1) control module

27. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 Wheel SlippageWheel Slippage, is the wheel speed in relation, is the wheel speed in relation
to vehicle speed.to vehicle speed.
 If vehicle speed is faster than the wheel speedIf vehicle speed is faster than the wheel speed
slippage is negative. And the wheel mayslippage is negative. And the wheel may
become lock-upbecome lock-up

28. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 If vehicle speed is slower than wheel speed.If vehicle speed is slower than wheel speed.
Wheel slippage is positive.Wheel slippage is positive.
 Positive wheel slippage occurs when a wheelPositive wheel slippage occurs when a wheel
is spinning.is spinning.
 NOTE:NOTE: Late model vehicles use the sameLate model vehicles use the same
ABS components with traction control.ABS components with traction control.
Traction control prevent a vehicle fromTraction control prevent a vehicle from
spinning out of control.spinning out of control.

29. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 The best braking action occurs at between 10-The best braking action occurs at between 10-
20%.20%.
 If vehicle speed and wheel speed is the sameIf vehicle speed and wheel speed is the same
wheel slippage is 0%wheel slippage is 0%
 A lock-up wheel will have a wheel slippage ofA lock-up wheel will have a wheel slippage of
100%100%

30. ANTI-LOCK BRAKESANTI-LOCK BRAKES
 In a diagonally splitIn a diagonally split
system brake system thesystem brake system the
left frontleft front andand right rearright rear
brakes are controlledbrakes are controlled
together.together.
 Diagonally split systemsDiagonally split systems
offer an added safetyoffer an added safety
value.value.
Master
Cylinder

31. AdvantagesAdvantages
 It allows the driver to maintain directional stabilityIt allows the driver to maintain directional stability
and control over steering during brakingand control over steering during braking
 Safe and effectiveSafe and effective
 Automatically changes the brake fluid pressure atAutomatically changes the brake fluid pressure at
each wheel to maintain optimum brake performance.each wheel to maintain optimum brake performance.
 ABS absorbs the unwanted turbulence shock wavesABS absorbs the unwanted turbulence shock waves
and modulates the pulses thus permitting the wheel toand modulates the pulses thus permitting the wheel to
continue turning under maximum braking pressure.continue turning under maximum braking pressure.

32. DisadvantagesDisadvantages
 It is very costlyIt is very costly
 Maintenance cost of a car equipped with ABSMaintenance cost of a car equipped with ABS
is more.is more.

33. ConclusionConclusion
 Statistics show that approximately 40 % ofStatistics show that approximately 40 % of
automobile accidents are due to skidding.automobile accidents are due to skidding.
 These problems commonly occur on vehicleThese problems commonly occur on vehicle
with conventional brake system which can bewith conventional brake system which can be
avoided by adding devices called ABSavoided by adding devices called ABS
 If there is an ABS failure, the system willIf there is an ABS failure, the system will
revert to normal brake operation. Normally therevert to normal brake operation. Normally the
ABS warning light will turn on and let theABS warning light will turn on and let the
driver know there is a faultdriver know there is a fault