Air Shift PTO

Yes, that is exactly what it does, and at 4 degrees (like this morning) just turning the pump puts a noticeable load on the engine. Hence I have been leaving the clutch in until adequate air is built up to allow disengagement.

 

Well, when you first turn the key on and the air pressure is low, the PTO is engaged, and the warning light on the dash is lit. After the air builds to about 60 psi the PTO will disengage and the dash light goes off. The load on the truck is noticeable as it turns the hydraulic pump. It is not a tremendous load as the pump is just cycling oil at this point, but it is noticeable.

Here are a couple of pictures of the air shift mechanism attached to the PTO.
There is a cap on each end; one of which contains the fitting to receive the air line. I am wondering if I can swap the caps from end to end, and probably reverse an internal spring, to get it to function so that it requires air pressure in the line to engage it. I am not sure what I will find inside, and also not sure if I will have to drain the trans fluid to do this. I don't think so as it should be separated by the PTO.

 

Normally we don't hold the clutch in after the engine starts. But once it gets down around 0 degrees I really like the engine to run freely for a bit before turning the PTO pump. Temperatures above freezing I do as you suggest.

 

Thanks gentlemen, I believe I'll try that. I should be able to remove those caps without the transmission oil coming out, correct? (I know you two have a sense of humor, perhaps I should ask someone else?)

Thanks for everyone's help!