Antilock Brake Systems or ABS is a automobile
technology that has been incorporated since 1985
in passenger cars and according to the Fatal
Accident Reporting System, fatal crashes were
reduced by 24 percent, and nonfatal crashes by
14 percent.
However, ABS was introduced as standard
equipment most of the cars during 1991-92 inthe
US.
The fundamental safety problem addressed by ABS
is that drivers are able to optimize the
pressure they apply on the brake pedal, given an
sudden emergency situation or a slippery surface
like a wet road or gravel.
With excessive braking,the wheels lock and the
vehicle can yaw out of the driver's control
(rear-wheel lockup), or go straight ahead,
impossible to steer (front-wheel lockup).
On most road surfaces, a skidding vehicle needs
longer distance to stop than a vehicle with the
brakes applied and wheels still rolling. The
objective of ABS is to take over the
optimization task from the driver. A four-wheel
system is intended to keep all the wheels
rolling during panic braking, to prevent yawing,
to allow steering throughout the emergency and,
on many surfaces, to shorten the stopping
distance.
Multivehicle crashes on wet roads,striking
another vehicle in the rear, or striking a
stopped vehicle is considerably reduced by ABS.
However, studies show dry road crashes are no
way helped by ABS. Also, running off the road,
rollovers are a common ABS problem.
Ideally ABS help prevent lock up. Also, at an
emergency high speed braking, the brake pedal
starts pulsing violently (Experienced this in a
VIVA-Accent). The ideal thing to do is grit your
teeth and brake hard.
In a non ABS car, the ideal way to stop in
emergency is to pump the pedal. In an ABS car do
not do so as this will take longer in an ABS car
to stop.
How does an ABS work? I assume most of us know
and if we do not we can always check it on How
Stuff Works? or the Internet.
The basic principle is that when a wheel is
about to lock up, the speed sensors that is
located in each wheel sends a signal to the
computer and it effectively assigns the correct
pressure to each wheel to conversely affect a
non skid situation.
There are 3 kinds of ABS-
1) Four-channel, four-sensor ABS - this has a
speed sensor on all wheels and the controller
controls each wheel. Most common and ideal
setup.
2) Three-channel, three-sensor ABS - mostly
found on pickup trucks, front wheels have
individual system and the rear has a single
system.
3) One-channel, one-sensor ABS - also found on
trucks, which controls only rear wheels.
**Dates and percentages and sources from
Insurance Institute for Highway Safety** |