Quote Originally Posted by dreamchasers View Post
Jon,

My 95, on a 94 chassis, dumps the tag axle on loss of aux air. I have traced the pneumatic drawings for my coach and think I know the reason.

On the passenger side-rear, accessible through the access door in front of the chassis battery access door, a pneumatic cluster in located. This manifold is sourced by the aux air system. Through a 24 volt relay I think (Have not checked out that portion of the logic yet) is controlled by the Allison Transmission (After obtaining a speed of 15 or greater, the 24 volt relay is activated, routing supply air to the Norgren), air is routed to the supply of a Norgren that controls the tag release. When air pressure is loss on the aux system, supply is lost to the Norgren controlling the tag, and air is released from the tag through the loss of aux pressure, via the Norgren supply. I have looked at this in detail and this could be worthy of a seminar. It is so simple it is complicated.


Your statement that pilot air is de-energized (with the key off) to the Norgrens is correct for the front and rear duals. It get tricky on the tag axle logic.

The tag axle dump upon loss of aux air will happen on a 94 chassis (It does on mine.)


Hector
If I am correct, that is the system that is tied into the stabilizators to prevent the tag from lifting above a certain speed.

If that is the case there are very few of us who have that system still enabled. To the best of my knowledge you, Jim C and I have that system. Prevost has been disabling the system.