PPT on Anti Lock Braking System With Full description

1. Submitted By:
Maneesh Kumar Shukla

2. INTRODUCTION
 An anti-lock braking system or anti-skid braking system is an
automatic safety system that allows wheels to maintain tractive
contact while braking the wheels from locking up (ceasing rotation)
and avoiding uncontrolled skidding.
 ABSs can improve vehicle control during braking, and reduce
stopping distances on slippery road surfaces by limiting wheel slip
and minimizing lockup.
 It is an automated system that uses the principles of Threshold
braking which were practiced by skillful drivers with previous
generation braking systems.

3. COMPONENTS
There are four main component of ABS;
• A Speed Sensor is used to determine the acceleration or
deceleration of the wheel. These sensors use a magnet and
a Hall Effect Sensor or a toothed wheel and an electromagnetic
coil to generate a signal. The rotation of the wheel or
differential induces a magnetic field around the sensor.
Hall Effect is a transducer that varies
its output voltage in response to a
magnetic field

4. There is a VALVE in the brake line of each brake controlled by
the ABS. On some systems, the valve has three positions:
 In position one :the valve is open; pressure from the master
cylinder is passed right through to the brake.
 In position two: the valve blocks the line, isolating that brake
from the master cylinder. This prevents the pressure from rising
further should the driver push the brake pedal harder.
 In position three: the valve releases some of the pressure from
the brake.

5.  PUMP in the ABS is used to restore the pressure to the
hydraulic brakes after the valves have released it. A signal from
the controller will release the valve at the detection of wheel
slip. The controller will modulate the pumps status in order to
provide the desired amount of pressure and reduce slipping.
 CONTROLLER is an ECU type unit in the car which receives
information from each individual wheel speed sensor, in turn if
a wheel loses traction the signal is sent to
the controller, the controller will then
limit the brake force (EBD) and
activate the ABS modulator
which actuates the braking
valves on and off.

6. APPLICATION
 The controller monitors the speed sensors at all times. It might
take a car five seconds to stop from 60 mph (96.6 km/h) under
ideal conditions, but a wheel that locks up could stop spinning
in less than a second.
 This gives the system maximum braking power.
 When the ABS is in operation the driver will feel a pulsing in
the brake pedal; this comes from the rapid opening and closing
of the valves. This pulsing also tells the driver that the ABS has
been triggered . cycle time is 16time/sec.

7. TYPES
They can be differentiated by the number of channels: that is,
how many valves that are individually controlled.
1. Four-channel:- Four channel systems control the brake force on
each wheel independently . In three channel systems, although
both rear wheels are monitored by sensors, if wheel lock if
detected on a single wheel the hydraulic braking pressure is
reduced equally on both wheels. This does not provide the level
of control of a four channel system, and thus three channel versions
are compromised and usually only fitted
to cars to save on cost. Most modern
cars now use a four channel ABS
systems which provide greater safety
in emergency braking conditions.

8. 2. Three-Channel:- Three channel systems control the braking
pressure on both front wheels independently, but control the
rear wheels together as a single unit.
3. One Channel:- This system is commonly found on pickup
trucks, SUVs, and vans with rear-wheel ABS. It has one
valve, which controls both rear wheels, and one speed sensor,
located in the rear axle. This system operates the same as the
rear end of a three-channel system.

9. WORKING
ABS uses wheel speed
sensors to determine if
one or more wheels are
trying to lock up during
braking. If a wheel tries
to lock up, a series of
hydraulic valves limit
or reduce the braking
on that wheel. This
prevents skidding and
allows you to maintain
steering control.

10. ADVANTAGES
 ABS maintains vehicle
steerability and stability
during panic braking.
 It reduces braking distance
by up to 10% or more
especially on wet surfaces.
DISADVANTAGES
the only disadvantage of ABS is
its higher cost.However, this
higher cost is completely offset
by the improved safety this
system provides. Also, auto
industry is working on
developing a low cost version of
antilock braking system.

11. CONCLUSION
 The rate of fatal motorcycle crashes per 10,000 registered
vehicle years was 37 percent lower for ABS models than for
their non-ABS versions.
 ABS appears to be highly effective in preventing fatal
motorcycle crashes based on some early adopters of
motorcycle ABS technology.

12. ANY QUESTION ?