Why flat tow in "Park"?

Why flat tow in "Park"? I have read all the posts for flat towing. Transfer case in neutral, OK...I get that but Auto trans in "Park" I don't get that. If the transfer case should bump into engagement the A/T is junk. Why not just put the A/T in neutral? Any body who is smarter than me got a thought?
gregg

http://www.naxja.org/forum/showthread.php?t=971880&highlight=flat+towing


http://www.naxja.org/forum/showthread.php?t=966111


http://www.naxja.org/forum/showthread.php?t=967313

tgregg said:

Why flat tow in "Park"?

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I have never seen a good explanation why the trans should be in Park but if the owner's manual says to do it, I would and do.
Here is my take. The AW4 does not self lubricate if the engine is off and the output shaft is turning. Keeping it in Park prevents any damage due to lack of lubrication.

I know many who tow Jeeps and have never heard of a problem with the transfer case jumping out of neutral into gear.
Jeeps are one of the most popular tow vehicles because they are so easy to tow.
My XJ has been towed a minimum of 30,000 miles behind our motor home without a problem using the Owner's Manual instructions.
Biggest problem with flat towing is that most states require brakes if the tow vehicle is over 1500 lbs.
Most vehicles used to tow also have similar restrictions listed in the Owner's Manual.

There is a simple explaination. Even with a tcase in neutral, there is enough viscus drag in the tcase to turn the input shaft if it is left to freewheel. The input shaft of the tcase is connected to the output shaft of the auto. For many decades now, autos have not had a pump that runs off of the output shaft. That leaves the output turning with no source of lubrication. The thought is that it will cause wear due to running the bearings dry.

Also by putting the auto in park, you can be assured that the tcase will be in neutral, otherwise you will know it immediately. If you left the auto in neutral and the tcase in gear, you would definately be turning the tranny with no lube.