What does the Dump rocker switch on dash control - HWH 6-pack or diff solenoid?

[Mike Shumack]

I'm having a problem with my front air bags. They wont deflate (which is probably why my front end is so bouncy on rough roads).

I started working on this because the front ride height was a high so I tried to adjust the front Ride Height Control Valve and discovered air will not exhaust when I rotate the valve body downward.  So, I ordered a new RHC valve and installed it today to find that its doing the same thing.

Then I removed the line coming "out" of the RHV going "to the front air bags" and no air is coming out. I believe there should be a straight path from the RHV through the HWH Travel solenoids to the Air Bags. I checked the Travel solenoids (16 ohms) and they get magnetic when energized (so they are working). Maybe something inside the HWH body is blocked.

But air is going into the bags. I can manually deflate the bags using the HWH lower" button, and the bags deflate. Putting HWH into Travel mode and the air bags inflate.

So why can't I get any air on the line at the RHV coming from the air bags?

There is a Dump rocker switch on the dash. I'm not sure if this goes to the HWH manifold to dumpo air (the HWH control panel has a Dump button already) or if there is a dump solenoid somewhere in the front end - maybe between the RHV and the HWH 6-pack. I cant find anything (but view is limited).

Any ideas?

[Fred Brooks]

    Mike, Is there a dedicated dump switch for the tag axle only? They installed it for tight maneuvers so the tag would not scuff so bad on sharp low speed turns. Not sure if this applies to your coach.
   Not sure why the front axle is not returning to travel height. Gerald is real good at this stuff, give him a call. Fred

[Mike Shumack]

I think I got this fixed.
I removed the two Travel valve solenoids and brass valves from the HWH 6-pack. I had a couple of the brass valves left over from when I rebuilt the rear 6-packs so I installed those (used the same coils). It looks like the brass valves were not allowing air to pass threw even though the electrical part (the coils) where working. I'm still not sure how the air bags were filling - but at least the RHV is letting the air out as needed now.

On the Dump Switch. It is not the same switch as the Tag Lift. I never used it before but it seems that when you hold the Dump rocker switch down all the air bags deflate. I can do the same thing using the HWH Lower button, so this switch is redundant. Maybe Beaver installed this button in case one didn't have the HWH air leveling.

[Fred Brooks]

   Another consideration concerning solenoid valve and height valve failure is dirty air. Most of us fail to drain our primary and secondary air tanks to remove accumulated moisture. Even though the engine dryer does a pretty good job addressing this issue, some moisture still ends up in the tanks. The last thing to air up when you start your coach is the suspension. This usually happens once the air reaches 100 psi. Once water and rust get into your height control valves and leveling solenoids stuff starts to work slower and eventually plug up. Hope this helps, Fred

[Mike Shumack]

Ride Height Valve is working now. I can manually rotate the valve body and add/remove air - but I noticed the passenger side air bags are about 3/4 to 1" lower than the drivers side (measuring from top plate to bottom plate). I don't know if it has always been like this. The last (only) time I checked ride height on only checked at one of the front air bags.

The bags should all be getting the same air pressure (it's a single line from the RHV). And I don't see any leaning of the coach.
Could different weights on each side of the front axle (say 7,000 lbs on passenger side front tire and 7500 on drivers side tire) cause the airbags to have different heights?

[Fred Brooks]

   Mike, Have you ever had each wheel weighed independently? The Escapee's RV club used to conduct rally's and offer the service. Not sure if FMCA offers it at their rally's.
  Coach leveling is controlled by the rear height control valves. If the driver's rear was a little higher it would compress the right front a little. Perhaps if you could have the coach on known level ground and air it up, then go around and take measurements from the center of the wheel opening to the ground and see what it says. (that's how I have done it after changing a height control valve for a customer). Fred

[Mike Shumack]

I had the Smart Weigh (Escapees) done last year.

On my trip last week, I got another weighing on a CAT scale (Pilot/Flying-J truck stop). It was pretty close to the Smart Weigh (15,520 front axle, 22,120 drive, 5760 tag; 43400 total). I don't think the CAT scale is as accurate since you have to position the rig on the scales just right (the drive and tag are on separate scales but the tag is on scale sized for a trailer so the weight is just at the tip of the platform). According the CAT weights I'm over on the Steering and Drive axles, and under on the Tag.

[Fred Brooks]

    Not sure what the remedy is. Perhaps someone with more chassis experience could chime in. When I had mine weighed by Escapees they showed me where my drivers side drive axle was over-weight. I can't remove the radiator or the bedroom slide-out. I'm reasonably sure that Rockwell has plenty of redundancy in there specs. (hopefully). Fred

[Mike Shumack]

   
  Coach leveling is controlled by the rear height control valves. If the driver's rear was a little higher it would compress the right front a little. Perhaps if you could have the coach on known level ground and air it up, then go around and take measurements from the center of the wheel opening to the ground and see what it says. (that's how I have done it after changing a height control valve for a customer). Fred

That's a good suggestion Fred.
I'll check the rear air bags heights. Possibly one side RHV out of adjustment a little and that's putting additional weight on the front-right causing those air bags to squat a little lower.

[Fred Brooks]

   Thanks, Getting back to your original question about the dump switch on the dash board reminds of a customer that said he used it to get under his carport. He said all he needed was 2" to clear his air conditioners so he held the switch down as he backed in. Not a good idea if you forgot when you left.....LOL Fred