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8/2/2019 Anty Lock Braking System (for Seminar)
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ANTI-LOCK BRAKE
SYSTEM
AJAY SINGH10/FET/EE(L)/2001
6TH SEM, EEE, 2ND SHIFT
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Presentation Outline
Introduction (ABS)
History of ABS
Theory ABS Components
Type of ABS
Disadvantages
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INTRODUCTION
An anti-lock braking system (ABS) is a safety systemon motor vehicles which prevents the wheels fromlocking while braking.
The Anti-lock Braking System is designed to
maintain vehicle control, directional stability andoptimum deceleration under severe brakingconditions on most road surfaces
It does so by monitoring the rotational speed of eachwheel and controlling the brake line pressure to eachwheel during braking. This prevents the wheels fromlocking up.
A rotating road wheel allows the driver to maintainsteering control under heavy braking
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HISTORY
1929 Anti-lock braking systems were first developed for aircraft.
1975Ford also introduced ABS
1978Bosch and Mercedes-Benz introduced the first completely
electronic 4-wheel multi-channel ABS system.
1988BMW became the world's first motorcycle with ABS
1997Suzuki launched its GSF1200SA (Bandit) with ABS
Today ABS has become a standard equipment even for small cars
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IMPORTANCE
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THEORY
When the car brakes (normally ) wheels exert a forward forceon the street which less than maximum static sliding friction
If the driver brakes very hard it can occur that the maximum
static friction is surpassed and the wheels lose their grip and begin
sliding
The amount of traction which can be obtained for an auto tire
is determined by the coefficient of static friction between the tire
and the road. If the wheel is locked and sliding, the force of
friction is determined by the coefficient of kinetic friction
A tire that is just on the verge of slipping produces morefriction with respect to the road than one which is locked and
skidding . So locked wheels are less effective in stopping on a road
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Physics 101: StaticFriction is Greater thanMoving Friction
ABS IS Computer
Controlled Brake PedalPumping
ABS Allows the Driver
To Maintain ControlDuring Hard Braking
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With out ABS
With ABS
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Wheel Speed Sensor
The wheel speed sensor pickup has a magnetic
core surrounded by coil consist of a magnetic
pickup and a toothed sensor ring.
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ABS ModuleThe ABS control module is a microprocessor and
uses input from its sensors to regulate hydraulicpressure during braking to prevent wheel lockup
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Hydraulic Motor
The hydraulic modulator or actuator unit
contains the ABS solenoid valves for each
brake circuit
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Pump Motor and Accumulator
A high pressure electric pump is used in some ABS systems to
generate power assist for normal braking as well as the reapplication
of brake pressure during ABS braking
The fluid pressure that is generated by the pump is stored in the
"accumulator."
The accumulator on ABS systems where the hydraulic modulator is part
of the master cylinder assembly consists of a pressure storage chamber
filled with nitrogen gas.
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Types of ABS Systems
By the number of channels-
Four-channel, four-sensor
Three-channel, three-sensor ABS
one channel one sensor
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Disadvantages
Increased braking distances under some limitedcircumstances (snow, gravel, "soft" surfaces),
Creation of a "false sense of security" among drivers
who do not understand the operation, and limitations ofABS.
The anti-lock brakes are more sensitive on thedamper condition. The influence of the worn components
on the performance of the vehicle with anti-lock brakes ismore significant than without anti-lock brakes, thestopping distance with defective shocks is by meterslonger for the presented simulation scenario
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