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ABS
Thanks very much to all who responded to my original posting, both in
the digest and direct to me by email. Everyone's reply was courteous,
which was better than I expected considering the tone of the original
posting. I was in a bugged mood the day I sent it, and didn't intend
it to be as harsh as it turned out. Hopefully this posting won't turn
out nastier than I intend. Sometimes I get a bit steamed about things.
I have been answering the responses directly, but I think I can make
the points I have been making in the individual responses by answering
one in the digest.
Tom....
>Why ABS? Because, when you are not on a track under controlled
>conditions, it offers many advantages to human-only control:
I think the idea that it is desirable when you are NOT ON A TRACK is an
interesting point.....
What is the difference between when you are on a track and when you are
not?
When you are on a track, you want the car to do exactly what YOU want
it to do, to slide if you want it to, to fishtail if (for reasons best
known to yourself) you want it to, etc.
You dont want any of your decisions to be overridden by someone else's
idea of what should be happening under those particular circumstances.
WHY WOULDNT YOU WANT THE SAME CONTROL OFF THE TRACK?
>1) ABS can pump the brakes 15 times a second. A human can't.
>2) ABS can respond in milliseconds. A typical human has a reaction time
>of 1/2 a second to a panic stop lock up if he/she is very good. At 60
>Mph, that's 44 feet.
Believe me that I am not trying to be a holier than thou type when I
make this point, but a "PANIC" stop means that what stopped first was
not the wheels but the brain of the driver.
I'm sure others can do it, but I can't think of any circumstances where
if you had not fallen asleep, and you were aware of your surroundings
(traffic conditions, road conditions, atmospheric conditions) you would
need to make a PANIC stop.
If you leave sufficient space between the car in front of you and your
car, there is no reason you should ever have to be so out-of-control
when stopping that it takes a computer to stop you. If you are
tailgating, not ABS or anything else will save you from rear-ending the
car in front if it stops suddenly. Your reaction time to press the
brake wont be fast enough.
Someone responded to my original posting about ABS by telling me about
how ABS saved him from crashing into a truck that was going by an
intersection where the stop sign was obscured by a tree.
I took drivers education way back when, and they taught a few "guiding
principles"....
I was taught to treat ALL intersections as if there were either a yield
or a stop sign there.
I'm glad that ABS saved him from hitting the truck, but if he had
slowed down when coming to the intersection, he wouldn't have needed
ABS to stop in time.
"Drive as though all the other drivers are passed-out-drunks, and you
will never be caught by surprise". Assume the other guy is going to run
the stop sign or the red light, or cross the double line into your
lane, etc.
Know where your escape route is. That means if you are on a highway,
be aware of whether the shoulder is clear. Then if something is coming
at you or appears in front of you (like a truck, or a deer), or if
somebody suddenly stops in front of you or cuts you off... you can duck
onto the shoulder, or into the other lane, or wherever you know there
is space because you are aware. No panic stops needed.
The point I am trying to make with all this is that if you pay
attention to what you are doing, and to the conditions around you, you
should never be caught by surprise and need something like ABS to save
your bacon. If there is black ice on the road, what the h--- are you
doing driving on it?, or if you have no choice, you should be going
slowly enough with enough space around you to allow room for a
coast-to-a-stop if needed. If it's raining and the road is wet
(another point many people who responded to me made), maybe you should
be going a few mph slower????? Then you wouldn't hydroplane, and you
could stop normally. etc. etc.
I have been driving since 1967, and the last time I slid into another
car or anything else because of locked wheels was 1969, so please
understand that I'm not just shooting off my mouth with this issue.
ABS is used by many people (hopefully not digest participants, whom I
credit with being much better drivers than the usual mob of morons you
find on the road) to save them from the consequences of poor judgement
and inattention.
>3) ABS can respond to and optimize braking to each wheel under
>left-right split mu and front-rear apportioning situations. A human has
>only one control input.
That's the only point where I have to concede ABS has it over
do-it-yourself braking.
I had a BMW 1600 in 1970 which had manual brakes, and I developed a
very good feel for the brake pressure required on that car to achieve
various levels of stopping power. I now have a 2002 tii, which has
power brakes, but I have gotten the "feel" of the braking system on it,
and can apply pressure to almost but not quite lock the wheels (without
pumping them), to lock only the back wheels so I can still use the
front ones to steer, or to lock all of them as in "when in a spin, both
feet in". MY CHOICE, not a computer's.
>Personally, I would never consider buying any vehicle that did not have
>ABS.
What I would like is an on/off switch for ABS, so if you want to use
it, you can, and if you don't want it, you can shut it off.
Thanks for the bandwidth.
Ira