Air Bag Question

jtharley · 11-03-2008, 07:40 AM

Here's the scoop...

I just took the motorhome to the pole barn to store it for 2 months. When I got her in I dumped the air and noticed the front air needle went down but the rear air needle stayed over 100 psi.

Went back the next day to finish winterizing and started the coach. Everything was normal, the air pressure built up and both front and rear air guages where normal. When I went outside the coach I notice the rear end did not "lift" like it normally does. Dumped the air and started the coach again........checked the rear tires and they did not seem to lift up but the front did and both guages read over 110 psi.

I'm going to take the coach out for a ride later in the week to see if the rear lifts up. If not is there any suggestions? Could it be a stuck valve? Why would the guage read over 110psi when I know the rear of the coach is not filling up.

I don't want to wait till January when we leave for Florida and have a problem on a day when it is 10 below zero and delay our trip.

I have a 2006 Winnebago Vectra on a freightliner custom chassis.

jtharley · 11-03-2008, 07:40 AM

Here's the scoop...

I just took the motorhome to the pole barn to store it for 2 months. When I got her in I dumped the air and noticed the front air needle went down but the rear air needle stayed over 100 psi.

Went back the next day to finish winterizing and started the coach. Everything was normal, the air pressure built up and both front and rear air guages where normal. When I went outside the coach I notice the rear end did not "lift" like it normally does. Dumped the air and started the coach again........checked the rear tires and they did not seem to lift up but the front did and both guages read over 110 psi.

I'm going to take the coach out for a ride later in the week to see if the rear lifts up. If not is there any suggestions? Could it be a stuck valve? Why would the guage read over 110psi when I know the rear of the coach is not filling up.

I don't want to wait till January when we leave for Florida and have a problem on a day when it is 10 below zero and delay our trip.

I have a 2006 Winnebago Vectra on a freightliner custom chassis.

jtharley · 11-03-2008, 09:58 AM

All is well again.

Went and started the coach and released the air brake. Moved it out of the pole barn and noticed the air bags all filled up. Took it for a ride and dumped the air........restarted the coach again and the bags filled like normal.

Yea.......

jimandsue60 · 11-03-2008, 10:08 AM

I am glad I can help

Jim

AA4WP · 11-04-2008, 03:58 PM

JTHarley: A common cause for air bags not filling is their not responding to the electrical impulse initiated by pressing the "store" button (for the levelers). I spent about 1K bux in Tolleson, AZ this past winter because none of the air bags would fill. They ordered and installed the main air bag fill valve; if I had known then what I now know, I would have punched the store button more than the one time one usually punches it to store the levelers. There are some other posts on this forum regarding this phenomenon. By the way, my air bags have not filled since the air valve replacement a couple of times; the first time they would not fill (after that repair) I sought help here and found the cure. I believe that the valve either has a front and a rear valve, or that there are two discrete valves for front and rear. In any event a second press of the button should help. I should have known of this possibility to solve the problem since the tech at Freightliner could not get the bags to fail to inflate. I thought I was being prudent to have the "offending" valve replaced. Live and learn.

Wendell

SargeW · 11-05-2008, 03:05 PM

I have just finished a "Camp Freightliner" class in Gaffney where I learned an interesting tid bit of information. The two air pressure gauges we have in the dash panel have different functions. The rear air pressure gauge is dedicated to operating your air brakes. The front gauge is operating your air bags. In an emergency situation like the tank for the rear gauge fails, it will bleed pressure from the front tank to work your brakes.

So the fact that your rear needle stayed over a 100 psi is a GOOD thing. I never knew that either until I attended the class. Relax, all is working as planned!

Sarge

jtharley · 11-05-2008, 03:09 PM

This is what I love about the RV forums....so much to learn even after 8 years of owning motorhomes....thanks all.

JT

wagonmaster2 · 11-05-2008, 06:20 PM

SargeW -- Appreciated your response. I've always wondered (I've only had a DP for 4 years) why after dumping the bags that the front gauge was always below 60 lbs but the rear was generally above 100 lbs. Always thought the front gauge was for the front bags and the rear gauge was for the rear bags. Never entered my mind that something had to be applied to the brakes. Being used to gas engines and hydraulic brakes for 50 years, don't know what I'd have done without this forum. Keep the great information coming.
Wagonmaster2
2004 Meridian 36G

cbeierl · 11-05-2008, 08:25 PM

Actually, I believe that you'll find that the front air tank serves the front brakes and the air suspension while the rear air tank serves the rear brakes.

SargeW · 11-06-2008, 07:06 AM

Well, I'm not the expert on air systems, just relaying what Mike (the instructor) told us at Freightliner. I tend to believe him.

I thought the same thing Wagonmaster. Actually I "assumed" that was how they worked. The Freightliner school taught me several things that I didn't know, and verified some that I did. Great school.

AA4WP · 11-06-2008, 08:41 AM

SargeW:

While on this sub-topic, I am amazed at how much there is to learn about the DP chassis. What I would like to see is an on-line version of the "Camp Freightliner". My first impulse is to just take the the operation of a typical DP chassis on faith, but I am regretfully beginning to realize that one does need to understand the various hidden components of these remarkable chassis(s). (is there a plural form for chassis?).

I have tried to use the Freightliner web site to find info about the XC chassis, similar to the prints one can receive from the Winnebago site. I cannot even figure how to register successfully. Anyway, nice to know what those two guages are representing. I "assumed" front and rear brakes. Just didn't move until the buzzer went off.

Wendell