[Floridian]

Typically, Allison transmissions are wired to NOT allow the diesel engine to shutdown if the transmission is an another other than Neutral. Sounds like that is what happened to you. The linkage control for the transmission is on the passenger side of the coach on the side of the transmission. When the linkage is fully extended, it is in reverse, one notch forward is neutral, then drive, etc. Do you have the Stone Bennett Air Shifter on yours? (toggle switch to change gears rather than a transmission level). Those do need air pressure to shift gears.

When the tanks have been depleted of air from sitting for an extended period, it is always a good idea to wait until you build up pressure (preferably the full 120 psi) before trying to shift gears.  With less than 60 psi the drive axle brakes will be engaged and you won't be able to move the coach anyway, that is the reason you couldn't get the coach to move. That is a required safety feature since otherwise you would have driven off with NO brakes at all.

You mentioned that it took 10 minutes to reach 60 psi. It does take a number of minutes for the tank to air up, especially if the brake tanks are depleted and the suspension air bags are down.

I prefer to wait until I hear the air blow-off valve actuate prior to putting attempting to put the coach in gear. I also visually verify that the rear fenders are lifted off the drive axle tires to prevent the fenders from cutting into the tires. Typically by the time the air blow-off valve dumps, the fenders are well off the tires but the thought of tearing up a perfectly good pair of expensive tires because I didn't wait long enough is plenty of incentive for me to do a walk around before shifting into gear. That may not be an issue on the pre-1990 Newells but it certainly is no mine.

I do have one of those Stone Bennett air shifter, PO (Ron) mentioned he changed something in it (can't remember exactly, it was too much information in one sitting).

I did have the airbags deflated and didn't walk around before moving the coach but that is a great thing to do as a general check (added to my list). 

By the way I was told that I shouldn't have the engine idling for more than 5 minutes, that is not good for the engine (oil pressure) so I don't know how to do this without having the engine running. I do have a small air pump right behind the little motor that provides air for the generator, but haven't found how to turn it on yet (I guess it is 110v) will that little compressor build up pressure for the Brakes and the rest of the different systems?

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Floridian, You can see the lever about midway just above the pan. This one appears to have a shift cable end attached to it.

Thank you so much for taking the time to share that picture! I'll take a look at it tomorrow and see if I can reach that from the engine compartment just to be aware of what I'm dealing with in case something like no air situation happens.

Again, thank you!

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My '87 shifter is in reverse when fully retracted. It bolts on using the transmission oil pan bolts & is mounted horizontal.
The 'neutral only shutdown' is in the Stone Bennett shifter wiring at the driver.

A friend's '87 uses an electric actuator to shut down the engine, mine needs air. . .

I'll take a look at it tomorrow and see if I can move that with something and have that something in one of my storage bays in case of an emergency.