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Topic: Air leveling question (Read 1688 times) previous topic - next topic

Re: Air leveling question

Reply #25 –
Quote from: saddlesore –
Question.... where is the sensor that tells the 12v air compressor to turn on and add air?
I can't say how your system works, because your coach is much newer than ours.  You need to determine what HWH leveling series is fitted to your coach, and then find the online documentation, which should answer your question.  Find your system here:

http://www.hwhcorp.com/ml17785_01_nom_pr_lesy.pdf  (Keep scrolling down - it is a long document)

On our coach, the HWH 600 Series control box looks at the 85 psi pressure switch that is mounted on the rear 6-pack manifold.  If system air pressure is less than 85 psi, and if the control box receives a call for any kind of "raise" function (either manually from the operator or from the auto leveling system), then the 12V aux compressor will run.  On our coach, the aux compressor does not try to fill any of the three pressure tanks - the output goes directly to the front and rear 6-pack manifolds, and from there to the appropriate air bags.

As I said, your system may operate differently.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Air leveling question

Reply #26 –
Good clear and concise explanation. Reading it made me wonder about the possibility of changing the 10 psi switches for a higher value, say 15 or 20psi. That may be enough to keep the tires clear of the skin above in most leveling situations. Better yet, an adjustable pressure switch so that you can tailor the low point to protect the wheel wells... One of these days, I may have time to investigate. In the mean time, rebuilding the six packs, replacing the tank check valves, and finding all the leaks I can, as well as putting in my new air dryer to make the system function closer to design specs comes first. All that was supposed to be done before this trip. Oh well, it gives me something to look forward to when we get back. Our coach loses level, usually sagging to driver's side rear over night. The usual way I find out is when the bedroom sliding door slowly creeps open in the middle of the night :o
Don
Quote from: Chuck & Jeannie –
If you prefer manual leveling (some members do) and are happy doing it that way, then that's all that matters.

BUT, for the benefit of our recent members who may be new to "auto leveling", I would like to point out that the HWH automatic leveling system is designed so it should not twist the frame or stress the windshield.  This assumes that the leveling system is working properly, and that the two 10 psi pressure switches on the front 6-pack manifold are functioning correctly.

IF the above assumptions are true, then the HWH auto leveling system will do the following:

1.  It will attempt to level the coach by releasing air from the appropriate bags until level.

2.  If releasing air from either of the front corners results in air pressure in the bags dipping below 10 psi, then air release from the opposite front corner bags will be inhibited.

3.  If at that point the coach is not level, then the system will add air (using the aux compressor if required) to the appropriate bags until level is achieved, or until it gives up and the "EXCESS SLOPE" light comes on.

Since the HWH system stops lowering the front of the coach as soon as one (front corner) air bag pair is almost empty (i.e. on the mechanical stops), the coach frame should never be subject to any twisting force, and the windshield panels (especially on the GVs) should not suffer from any undue stress.
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Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson

Re: Air leveling question

Reply #27 –
Quote from: Don & Tys (AKA acousticart) –
...made me wonder about the possibility of changing the 10 psi switches for a higher value, say 15 or 20psi.
HWH had the same idea!  For some reason, Foretravel elected to install lower pressure rated 10 psi switches, at least in my 600 Series system.  Don't know why...

See the .pdf excerpt below from the HWH Leveling Systems Text Book, right column, 2nd paragraph from the top:

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Air leveling question

Reply #28 –
Quote from: Don & Tys (AKA acousticart) –
Our coach loses level, usually sagging to driver's side rear over night.
Mine is similar; the passenger side stays up much longer.
 
I have discovered that if I lower the passenger side to keep it level, it will stay level after the air pressure is gone. If I forget to do that soon after parking, it seems to stay unlevel.
 
Trent

Trent and Jean Eyler
2000  U295  4003  WTFE  ISC  350
Build#5603 MC#17385

Re: Air leveling question

Reply #29 –
Quote from: saddlesore –
Question.... where is the sensor that tells the 12v air compressor to turn on and add air?
Once in a while the 12 v will add air to the whole system (sometimes it does but most times it does not), but not for leveling.

This could be a couple of things, a little more "observational behavior" can help with diagnosis (either here or some info you can share with HWH to get assistance):

Does the auto leveling work fine with the coach engine running and supplying air when raising a corner/side is needed?

With the engine off, does the auto leveling work as intended when it needs to exhaust air, but it just doesn't seem to work to add air/raise the coach? 

If you manually try to raise a side/end without the coach engine running, do you hear the raise solenoids click (someone needs to be outside, close to the coach to listen) and does the aux compressor come on?

Does the aux compressor come on (with the engine off) when you go to deflate the slide bladder(s)?

There are a couple of means that turn on the aux compressor, and it has 2 power supply lines.  One is fused inline with the compressor (usually), the other is a 12V breaker.  I've read of a few owners that have added a switch to kill all power to the aux compressor, but since both MOT and OTM have worked on your system, if one was there they should have seen it.  There is also the HWH controller which has to send the signal to the compressor that something needs to be raised and it's not going up, so aux compressor assistance is needed.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Air leveling question

Reply #30 –
Our coach stays level with the Aux compressor when the tanks are at zero PSI.

Remember that all systems have specs that are within tolerance.  The HWH leveling system may not put the bubble in the dead center of the bulls eye, but it can still be operating within HWH factors specs.  Here is the spec quoted from HWH's Air Leveling Textbook:

The sensing unit has an accuracy tolerance of +/- 3/4 degrees. This translates into approximately 1 inch from side to side and 5.4" from front to rear on a 36' vehicle when the sensing unit is mounted in the middle of the vehicle. The length of the vehicle and where the sensing unit is mounted can change these figures.

I've monitored our system with a bubble level that has degrees marked on it, and it remains within tolerance.  Sure the bubble may move from the 12 o'clock position on the level to the 3 o'clock position, but it's always within the specs.

Our air system leaks down at a rate of 3 PSI per hour, which is twice as good as the Foretravel standard published in the owners manual, and worlds better than the DOT standard.  So I don't worry about chasing down leaks to get it better.

Chris

Re: Air leveling question

Reply #31 –
For now will just wait until the NW rally in Astoria, OR. might get to pick some brains there & more eyes (and ears) the better to surmise the situation..
A little update...
 Got to looking and the tall relay that goes to the Thomas compressor has 2 terminals on top, well...seems that these studs are both loose in the housing(I can twist one of them and it makes/breaks connection) and the terminal nut that goes directly to the compressor was loose as well, now have the compressor running and cycling as I think it should....(Unless it breaks connection again).
 went online to HWH and ordered a replacement...
And then discovered a hyd leak on the slideout connections @ a junction manifold block...grrrr
If it ain't one thing gone bad it's three..
'02 40' U320t  4010WTFS Build 6036 1 slide
Motorcade # 17841
SKP 151920
Retired truck driver
 5 million miler
Still have itchy feet for travel