ABS

[Darrell Norquay]

At 10:34 AM 1/29/97 -0600, John Hess wrote:

> This is why ABS is generally found to be ineffective on ice.

Tell you what, non-ABS brakes are sure as hell ineffective on ice as well!
Any amount of divine intervention is usually welcome under these circumstances.

There must be something other than the differential speed algorithm involved
in the ABS control.  If a 4 wheel lockup occurred, and the VSS reading went
from 20MPH to 0 in, say, half a second, the ABS controller should know
something is fishy.  As soon as the ABS cuts in, the wheels will start
turning, and the differential speed thingie starts working again.  However,
the ABS system has to cut out below some minimum wheel speed, otherwise the
brakes wouldn't work at all when the vehicle is not moving.  Not a safe
situation, to say the least. 

Also, I would think that ABS systems work in pairs, ie front wheels on one
modulator, and rear on another modulator.  It would be prohibitively
expensive to have a separate master cylinder connection and modulator valve
for each wheel.  They may still have sensors on each wheel, but controlling
them in pairs is (IMHO) much safer (and cheaper) than modulating each wheel
individually.

regards
dn
dnorquay at iul-ccs.com