Leans - HWH Issue?

[TerryM]

Thanks Jon,

I should clarify something on HWH system. It is not continuous adjustment, it activates every 30 minutes and checks and adjusts.

Most Norgren valves are less then 4 years old. Not sure on age of bags.

I will schedule a trip through CoachWorx on the way back down to Fort Myers.

Thanks

Terry

[Jon Wehrenberg]

You will be in good hands with the fellows at Coach Worx.

If the HWH is leveling with the key off think about this for a moment.

To lift your front end with the air bags I will bet is going to require more than 100PSI and I know some coaches that are fat in front can require as much as 120 PSI. So if your aux system cannot reach and maintain those pressures nothing is going to happen when the HWH asks for the front to be raised.

As to the rear.... We have had some nights in the coach when the wind was blowing we could actually feel the coach rocking. If the HWH is continuous or is sampling every 30 minutes it is at some point going to read an out of level situation due to the winds. If the wind is pushing the side and it compresses the lee side air bag while extending the windward side air bag it is going to call for the release of air in one side and a charge of air in the other, when in fact if left alone a good leak free system will not require anything so instead your aux air system is going to be asked every 30 minutes to make adustments. My rear air bags start to raise the coach at 70 PSI. I don't know their pressure when at ride height. My point is your rear air bag pressures may be within the compressor control switch range and even though HWH thinks air needs to be added (or depleted) the aux system isn't going to because the pressure isn't low enough to trigger the aux compressor.

When a non HWH coach is leveled, and the key is off the air is locked into the air bags. At least on a tight system. that means on a windy night you may feel motion, but not have to hear or have the aux air compresor work. Fix the leaks and you don't need to be monitoring the system for level or have a system on board that does.

[TerryM]

I called HWH today and talked to tech support. I told them the system worked great when the site was not level and not so great when site was level. They said the reason is that when the site is level the HWH automatic leveling sytem does not activate. Since it is not activated the auto-level is not working. I guess that is why it leans a little over time just like when it is in storage.

I have a HWH Series 680 system, not sure how other HWH systems work.

Terry

[Jon Wehrenberg]

Terry,

Take our advice and remarks with a grain of salt with respect to specifics on the air suspension system. The basics are somewhat the same for the Prevost level low system, but even then there are variations due to system changes over the years. What makes an internet analysis very difficult is modifications over and above what the Prevost system is, and to an extent to model year. There was a significant change to the logic on the Prevost level low system in the mid nineties and depending on how converters titled the coach, an early nineties shell can be treated by the owner's title as a later model. The best way for anyone to really know which system logic is employed is to look at the pneumatics based on the VIN number.

But to add to that difficulty one almost needs to know how the converter modified the Prevost suspension system. If your HWH functions with the key off, but some from the same converter will not function with the key off that is important. My Liberty suspension system is different from the Prevost system and it will not function withg the key off, yet on my previous bus, the automatic leveling function did function with the key off.

So the bottom line is while we can offer some basic information and advice, it has to be understood it can be wrong, or not complete.

But just to restate something I already have previously stated, an automatic leveling feature that operates with the key off had better have a constant supply of at least 120 PSI or it is likely to be useless in practical terms because most front ends, and especially heavy ones need to see that pressure to be able to raise the front through the full range. I don't know what it takes to raise a rear left or right at weights near the gross weight limits, but I suspect it also requires more pressure than the average aux air compressor is set to put out. The real key to avoiding the leans is not to have the system capable of leveling the coach with the key off, but to eleminate the leaks that lead to the leans.

[TerryM]

Thanks Jon,

My bus is right up to max GVWR so I'm sure you are right about the need for at least 120 psi of air. I read as much as I could find on the HWH system and my basic take-away was similar to what you pointed out - many different models, many different ways to do the same thing means an almost infinite number of possibilities.

I'm going to focus on the leaks and try to plug as many as I can find and see if that will get me mostly solved.

Thanks for your help. Just when I think I understand some piece of this I realize I know almost nothing. That's part of what makes it fun.

Terry

[Jon Wehrenberg]

Terry,

As you can imagine the coaches are complex. Problem solving, even for those professionally engaged in the business is made more difficult not only due to the number of Prevost design changes, but the wide variety of converters, and the number of design changes they also make over the years. As if that wasn't enough to frustrate almost anyone, there are the "upgrades" or owner requested changes over the years and the probability little of all of this is documented or easily accessed.

Any of us can guess, but until we are at the coach and can actually identify what we are dealing with (and even then) we have nothing but our educated guesses.