Seems like sticking with basics would be the key here. Maybe bells and whistles wouldn't be too hard to add later but I think it makes more sense to stick with what the bus has to begin with. In my case that does include kneel and rear raise but I think that's a side benefit at present.I don't think it has to be complex. Let's consider a simplest case, making some assumptions that may or may not be valid. First assumption: each air bag has a solenoid control valve that can pressurize and vent the bag. I know the air ride system is more complex than that but for now this works as a dividing line between old and new so everything I will suggest lies on the new side of this line. It will undoubtedly have to change as the exact characteristics of the old become apparent.So, here's where it gets really simple. Probably stupidly so but at least it is a starting point: For the autolevel, simple basic mercury switches. You can still buy those and they will handle solenoid level current with robust reliability. Various configurations are available, it should be possible to buy them in a 3 pole leveling switch which makes the rest of this dead easy. If not, two double pole units can be combined to make a leveling switch. We need at least two of those. Connect one to control the air solenoids across the main axle and you have side-to-side leveling. As a practical matter it may take two, wired opposite each other, one for each side. Then another switch connected to both front air solenoids for long axis leveling and a power switch to turn it on. I think that about does it. For the manual side double throw rocker switches to override the mercury switches should be about all that is needed. That's pretty simple and basic. As for justification, uh, to like, level the coach? Lots of places I'd expect to park will not be level, in fact I'd go so far as to say 90% will NOT be level, probably more than that. I built a tripod hydraulic system on my last RV and you can trust me when I say I feel deprived without it. That system had very long legs, far more than anything you are likely to see on an RV today but by damn I used them. I don't expect anything like that but it sure would be nice if the rig could sit level outside my shop without planks under the wheels.Jim
Go to the HWH site and look at the 'Air Level System" not the Active Air System just the plain old air leveling system and you can get good ideas using just a few solenoid valves it been used for years
I'll start:http://server51.hwhcorp.com/?page_id=64295#_3-1__WhatJim
Written by bus nuts, for but nuts.