I agree -- about 60 pounds is where the "low air warning" light/buzzer comes on.
My bus conversion has 4 air tanks and 1 air gauge -- My Freightliner Class 8 Conversion has 3 air tanks and 2 gauges. The truck will show 100 pounds or more on each gauge, but the main tank can be empty of air (as checked by dumping air via manual dump valves). The bus will show zero air when I still have air in two of the tanks. Guess it depends on where the gauge is installed in the air system. On my bus, I can see the compressor cycle between 90 and 130 pounds; on the truck one gauge sits around 130 while the other is at 115 --- and they don't move very much unless I apply a LOT of brakes. (They go to zero when I drain the tanks fully)
Air bags on the bus -- tag axle will empty out in about 6 hours --- (no check valve in the tag axle air system). All other air bags take about a week to show the coach to be somewhat lower so I run the bus once a month to get back to level once again (they all have check valves).
Have not noticed the truck air bags going down, but I don't have any weight on it either until hooking up my little trailer.
Will your truck pass the normal "Air Brake Test" that you perform prior to starting out in the morning on a trip?
don
|