re: Air Bag Problems

[gpatom]

Hey fellas I need some information on a problem I have ran into with my air system. My 1986 Neoplan metroliner has 4 air tanks. The main air tank supplies air to the 2 brake tanks thru check valves and to an auxiliary tank thru a pressure protection valve which supplies air to the air bags thru 2 check valves, 1 for the front and the other for the rear.At present I maintain a hundred to a 130 pounds of air in the main and the brake tanks, but have zero air in the auxiliary tank and air bags. Has anyone of you a suggestion as to where I should begin to look to solve this problem. I believe it is in the pressure control valve but not really sure. Also could it be something else.

[RTS/Daytona]

The purpose of the "protection valve" is to prevent a big suspension air leak from totally depleting the other tanks

The protection valve works by not allowing air into the suspension tank UNLESS the main tanks are above about 60 lbs

conversely - if you have a suspension failure the suspension tanks can bleed thru the leak to 0 lbs but the main tanks will stop supply air to feed the suspension tank at 60 lbs

soo sounds like the protection valve is stuck - not opening at approx 60 lbs

[gpatom]

Thanks RTS, I'll take the control valve apart and check it out. Hopefully that is the problem. If not will do another post.

[gpatom]

  I have taken the pressure protection valve off the bus and it is a Borg Warner, can anyone tell me if a Bendix 65 psi will work or what the cross ref. # is for a Bendix. I have two Neoplan books. The maintenance book says the valve is set at 65 psi and the parts book calls for a PR-4 and the truck parts people tell me that the PR-4 valve is a 85 psi valve. They also tell me that the PR-2 is a standard valve and will work. HELP!!