Saturday, August 30, 2008

Q: "Is it true ,that using"cruise control" in wet and slippery conditions will cause control loss of your car?"

2000 Jeep Grand Cherokee Laredo Steering WheelImage via Wikipedia (see original discussion)

Well, is it true? Let's think about that, and analyze the question properly. Diagram the assertion shows:

"using cruise control in wet and slippery conditions" --cause--> "control loss"


The problem here is a little tricky. Does the control loss come immediately? Some time after? Never, or only in certain circumstances?

The answer logically is "only in certain circumstances". Thus, logically, the answer to the original answer is FALSE. A certain SECONDARY condition must be met (such as one wheel spins and the other does not). You may just get lucky and never hit a bad patch and lose control. It's not a "given". Cruise control <> spin out.

Now let's analyze the actual situation itself.

Let's say you are driving in the rain, no cruise control, going straight, and one of your wheel is spinning empty (hydroplanes) while the other one has traction.

The following should happen:
* the side with traction PUSHES the car toward the side without traction
* driver hits the brakes and turns toward side with traction (opposite turn)
* the side-to-side weight transfer is balanced and neutralized
* due to braking, more weight went forward, reestablishing traction to both wheels
* driver regains control of vehicle

Let's revisit the scenario, but with cruise control this time

* side with traction pushes car toward side without traction
* driver hits the brakes (which disengages cruise control) and turns toward side with traction
* the side-to-side... hey, it's exactly the same thing!

See the problem?

I can hear you say now... But it's the TIMING! It takes TIME to lift the foot from the floor to the pedal! And the driver on cruise control is less likely to be alert! By the time brakes are applied he's already spun out!

But you just admitted what the problem really was... "Driver's lack of attention." It wasn't cruise control at all.

I rest my case.

P.S. At least one supposed mechanic ("I don't need to reference a website to know how cruise control works") claims that you will speed up uncontrollably if your wheel loses traction. Hah!

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