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The anti-lock brake system works off ABS wheel speed sensors. When
the ABS sensor detects that a wheel is rotating slower than the rest
of the vehicle because it is locked, it reduces brake pressure until
the wheel is rotating again, and then reapplies it until a wheel
slows down again. The tires never completely stop spinning, but they
slide on the road slightly each time the ABS pulses. If you look at
the road where a car was braking using ABS you see a checkered
pattern with a black mark for each ABS pulse/vibration. A skilled
driver can hold the car close to the traction limit without pulsing
back and forth, and spend more time utilizing the static traction of
the tires (which is greater than the dynamic or sliding traction).
ABS could do this if it only used a single pulse to determine how
much traction you had, but that would be dangerous because it
wouldn't know if that single pulse was an anomaly such as a piece of
gravel under the tire. A single pulse ABS would brake as good as an
expert driver under ideal conditions, but it would be dangerous.
If ABS reduced stopping distance, professional race cars would have
them, and they do not. They use "threshold braking." There are
numerous articles and studies out there that compare identical
vehicles with ABS to vehicles without, and stopping distance is
always shorter without if the driver is skilled. If you want I can
search and send you some links....
Tyler
On Dec 5, 2006, at 7:25 PM, Peter Frederick wrote:
My tires have NEVER slid with the antilocks, this isn't 1977 --
lots of
groans and some pedal vibration, but no tire slip at all.
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