Jim,

First a qualifier. I do not know if what I am describing below is standard on all shells, or if the converter has disabled the feature as I heard a certain large west coach converter did. Take the following with a grain of salt until you have verified it.

On 45 foot coaches that I have been beneath there is a device that is intended to prevent the rear of the coach from dropping when the tag air is dumped. Again, on the coaches I have seen from the underside, there is a switch that engages the tag axle air dump system when the steering wheel is turned to the extreme in either direction. When that occurs tag axle air is automatically dumped, and to prevent the rear from dropping air over hydraulic shock absorbers on the drive axle are brought into play, and they literally support the coach so it will not drop.

If you get under your coach, on the bulkhead forward of the drive axle will be a reservoir with a sight glass mounted in the middle. With the coach at the ride height, the reservoir should have the sight glass half full of Dextron III fluid. That is the hydraulic fluid which is forced into the hydraulic cylinders (which look like shock absorbers) that are mounted on the rear of the drive axle.

If you coach is dropping when the tag air is dumped, it could be because you do not have this system, the system is not functioning, or the system is low on hydraulic fluid.

Do not manually lift the tag as this may over-ride the operation of the system described above. There is insufficient information in my Prevost manuals to be able to say with certainty that what I am telling you is completely accurate.