ABS

Thu Jan 30 07:33:34 GMT 1997

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John Hess wrote:
>
> Unfortunately, on very slick surfaces such as icd, all four wheels
> lock up at once.  Generally the ABS systems work on a speed
> differential algorithm.  If a wheel is going appreciably slower than
> another (the others), then that wheel is considered locked and the
> brake system is modulated.  If all four are locked at the same time
> (at least at very slow vehicle speeds), the system sees the vehicle as
> stopped and is not activated.  This is why ABS is generally found to
> be ineffective on ice.

Aha!, It is the ice which is ineffective, not the ABS.
What they do is Pulse the wheels independantly. That way if the computer
"tests" a wheel by applying braking, then releasing. It can tell the
wheels' propensity to lock up, and try a lower braking value next time,
until It doesn't lock up.
I have tested this in slick mud, and it is quite amazing. However, if
there simply isn't anything to stop you, the ABS doesn't throw out any
grappling hooks. :)

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<DT>John Hess wrote:<BR>
&gt;&nbsp;<BR>
&gt; Unfortunately, on very slick surfaces such as icd, all four wheels<BR>
&gt; lock up at once.&nbsp; Generally the ABS systems work on a speed<BR>
&gt; differential algorithm.&nbsp; If a wheel is going appreciably slower
than<BR>
&gt; another (the others), then that wheel is considered locked and the<BR>
&gt; brake system is modulated.&nbsp; If all four are locked at the same
time<BR>
&gt; (at least at very slow vehicle speeds), the system sees the vehicle
as<BR>
&gt; stopped and is not activated.&nbsp; This is why ABS is generally found
to<BR>
&gt; be ineffective on ice.<BR>
&nbsp;</DT>

<DT>Aha!, It is the ice which is ineffective, not the ABS.</DT>

<DT>What they do is Pulse the wheels independantly. That way if the computer
&quot;tests&quot;&nbsp;a wheel by applying braking, then releasing. It
can tell the wheels' propensity to lock up, and try a lower braking value
next time, until It doesn't lock up.</DT>

<DT>I&nbsp;have tested this in slick mud, and it is quite amazing. However,
if there simply isn't anything to stop you, the ABS doesn't throw out any
grappling hooks. :)</DT>

<DT>&nbsp;</DT>

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