It's called DENIAL!! I also don't understand the attitude. It is no big deal to to understand your system. When it comes to vehicle air systems there is no such thing as maintenance free. take your unit to a GOOD truck repair center and ask them if the air system is maintenance free. Better yet stop at a scale and ask the DOT officer! There are hundreds of feet of air brake lines with unions, governor, tees, check valves, regulators, air chambers and moving parts. The leveling system on your coach runs on air and it too can go south causing a loss of air. Do you know how to do a 6 pack? Have you ever done a leak down test?? The S cams on a drum brake system require greasing that involves removing the wheel and drum. The simple tests I mentioned can be done from the driver's seat by any lay person.
Moisheh