I'm not an engineer, and I certainly don't claim to know everything, but I
think I may understand how this can happen. Please, someone correct me if
I'm full of it, but on most cars is not the "set speed" of the cruise
control set to the pace of the NON-drive axle? Then if the vehicle
hydroplanes, the non-drive axle is actually slowing, while the drive axle,
which receives messages from the cruise control, accelerates to compensate,
causing the wheel spin?
I've never used CC on my 4WD truck, 'cuz I'm offroading when in 4WD, and I
don't think the manufacturer would recommend using CC in 4WD, so the above
theory makes sense to me. . . does it to anyone else?
Mark mjh
----- Original Message -----
From: "David Homstad" <dhomstad@xxxxxxxxxxx>
To: <L-FORWARDLOOK@xxxxxxxxxxxxx>
Sent: Tuesday, February 04, 2003 1:24 AM
Subject: Re: [FWDLK] Safe Driving and cruise
> Now maybe I am not understanding the physics here, but this does not make
> sense to me. The function of the cruise control is to MAINTAIN a constant
> speed of the vehicle. I see 4 possible situations here:
> 1. If traction is lost to the rear wheels due to hydroplaning and the
> vehicle is under cruise control, the wheels would spin faster, causing the
> cruise control to reduce the amount of throttle to slow the wheel speed
down
> to maintain the “set” speed. Not accelerate the vehicle. Reaction time of
> the cruise system to close the throttle is important here.
> 2. If the vehicle is under manual throttle control and the driver
does not
> react to a loss of traction and holds the throttle steady, then the rear
> wheels will spin even faster than the vehicle speed. Reaction time of the
> driver to close the throttle is important here.
> 3. If the vehicle is on cruise control and slowing down below the
“set”
> speed due to a loss of traction, the cruise would position the throttle to
> maintain the rear wheels at the “set” speed. This would also cause the
rear
> wheel to spin faster (at the set speed) than the vehicle speed (slower
than
> the set speed). This may be what the patrol officer meant in the story
> below.
> 4. I think the proper reaction of a vehicle under manual control is
to
> remove all throttle immediately and coast until steering control is felt
> again. Do NOT apply the brakes.
>
> All of the above applies to a rear drive vehicle, like our ForwardLooks,
as
> described in the original story below. Situations 1 to 3 could mean loss
of
> control and a spin. The bottom line of the patrol officer’s advice is
good,
> even if the “acceleration” of the vehicle idea is wrong. In slippery
> conditions, do not use cruise.
>
> Front wheel drive vehicles may react very differently. When taking your
foot
> off the throttle to coast, the engine will cause some engine braking on
the
> drive wheels. If the drive wheels are in front, the front drags while the
> rear coasts. While coasting in slippery conditions, the rear wheels want
to
> move faster (less drag) than the front wheels. When the rear wheels get
> ahead of the front wheels, you are in BIG trouble.
>
> Significantly worn or bald tires are a major cause of hydroplaning.
>
> Dave Homstad
> 56 Dodge D500
> Minnesota, Land of 10,000 Frozen Lakes
>
> -----Original Message-----
> From: Forward Look Mopar Discussion List
> [mailto:L-FORWARDLOOK@xxxxxxxxxxxxx]On Behalf Of Floyd D. Harper
> Sent: Monday, February 03, 2003 4:57 PM
> To: L-FORWARDLOOK@xxxxxxxxxxxxx
> Subject: [FWDLK] Safe Driving
>
> FYI Group:
> Got the following from a friend and wanted to pass it on for safety's
sake.
> I'd never heard this but it makes sense.
> Floyd D Harper
> 1960 Dodge Dart Pioneer 2 Door Hardtop
> = = = =
> An individual had a wreck a couple of weeks ago and totaled their Lincoln
> Town Car. She hydroplaned on Hwy. 135 between Gladewater & Kilgore, Texas.
> She was not hurt, just emotionally rattled!
> She learned a lesson I'd like to pass on to you. You may know this
> already--but the highway patrolman told her that you should NEVER drive in
> the rain with your cruise control on. He said if you did and hydroplaned
> (which she did) that when your tires were off the road your car would
> accelerate to a high rate of speed (which it did). You don't have much, if
> any control when you hydroplane, but you are totally in the hands of God
> when the car accelerates. She took off like she was in an airplane. She is
> so thankful she made it through that ordeal. Please pass the word around
> about not using cruise control when the pavement is wet or icy. The
highway
> patrolman said this should be on the sun-visor with the warning about
> airbags.
> The only person she found out who knew this (besides the patrolman) was a
> man who had a similar accident and totaled his car. This has made her
wonder
> if this is not why so many of our young people are dying in accidents.
> Be careful out there!
>
> Perform random acts of kindness every day.
>
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visit:
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>
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