Lift Axle Sucks! (air)

Well I'd say you have a small leak somewhere. And i don't understand why it should drop the air pressure when you pull the brake knob out. Doing so doesn't exhaust all the air from your tanks. You could install a one way check valve in line to the air bags that lift the axle and that would prevent air pressure from bleeding back. But overall I'd just say to have some small leaks to look for. Or just take it back and have them set it up differently

 

What did they install for a lift valve? Lift bags get constant 120 psi from the air tank when the bags are lifted. Sounds like they have it plumbed wrong. Sounds like it's plumbed to either your emergency or service line.

 

Does your trailer have a dump valve that when you set the parking brakes it dumps the airbags? My trailer works that way.

If they tied it into the other airbags like they should have then they will dump with the parking brake.

As far as leaving it charged and you lose air you have an air leak someplace.

 

The valve, provided it's correct, it will either be normally open or normally closed. It should have a constant air supply from the tank, then a line or to lift and one to the down bags. The down bags supply had to come from the supply in the top of another bag so that the down bags have the same pressure as the other axle. Should be 4 lines into the valve minimum. The constant from the air tank is for the lift bags, do not regulate them. They are designed to work with 120 psi.