Flat towing Humvee with 40,000 lb military tow bar

[Mogman]

This probably has no association with flat towing a HMMWV, but I remember decades ago that I was told that you should never flat tow an automobile or truck with an automatic transmission if the transmission didn't have a rear oil pump. If you towed a vehicle without a rear oil pump, the spinning driveshaft didn't provide lubrication for the rear bearings in the transmission and the transmission would fail, regardless of whether the transmission was in neutral. I was told that if a rear oil pump wasn't present that the drive shaft had to be removed prior to towing, regardless of the distance towed. I don't know HMMWVs and don't know if they have a rear oil pump in the transmission or not.

If you have the trans in park then that is not an issue as the rear transmission shaft is not turning,

 

[HUMMER H1]

I can only speak from experience and don’t care what TM says,

Transmission in neutral, transfer case in neutral,

I towed humvees and H1 behind other vehicles,
and will keep doing the same if I need to again.

 

[Ls3rx7]

Might be a stupid question but how do you lock the steering to keep it from turning the wheels

 

[Coug]

Might be a stupid question but how do you lock the steering to keep it from turning the wheels

For towing you don't. The wheels will follow the path of least resistance, which is just following the tow vehicle. That is why a good quality tow bar hooked up properly is important, as it doesn't just pull the vehicle forward, it also forces it sideways when turning.

 

[HUMMER H1]

The centrifugal force will keep towed vehicle wheels in line with towing vehicle,

 

[Mogman]

I can only speak from experience and don’t care what TM says,

Transmission in neutral, transfer case in neutral,

I towed humvees and H1 behind other vehicles,
and will keep doing the same if I need to again.

You definitely do not want the transmission shaft turning as that will damage the transmission, this is why it is recommended to tow with TC neutral trans park.
Having said that the trans shaft is not too likely to turn with the TC in neutral but I would not risk it.

This would also insure the TC was in fact in neutral, if not the trans being in neutral could give you a false indication and the TC could still be in gear which would be a disaster.