[Richard]

Ok, here goes. It is all about twisting the frame. In the travel mode, the coach is actually suspended on a triangle. How so? There are only three height contol valves. One for each rear, and one only for the front. The right and left air bags for the front suspension are tied together pneumatically when in travel, so that the front is free to float side to side. The side to side movement while in travel mode is completely dictated by the rear height control valves.

Now when you put in level, each air bag is isolated by the six pack solenoids. The front air bags are no longer tied together. They are now separate. Even though the leveling computer is supposed to only level side to side, or front to back at a time. It is entirely possible when you level the coach to impart some level of twist to the frame.

Think of it in this totally oversimplified way. If you have a three legged stool, no matter how uneven the ground it is sitting on, each leg will touch and have equal weight. If you have a four legged stool, it is completely possible to have one leg not touching, and easy to see that one leg is not equally loaded. Imagine for a second that the top of the stool is not solid but somewhat flexy. On a four leg stool on uneven ground, the top would flex until all four legs had equal weighting. That is what I am trying to explain when I talk about the difference in coach air bags when in travel vs level. The key is the front air bags are connected in air pressure when in travel. Air pressure being what it is results in equal force on both sides of the chassis. When the air bags are isolated in level mode, then it is possible to have different air bag pressure side to side in the front.

[Chester Stone]

Perhaps this observation will help explain why. When in travel mode, the front of the coach utilizes one height adjustment valve thus keeping the frame from flexing or twisting. When in level mode, the front of the coach utilizes two height adjustment valves thus allowing the air bags to level the coach from four corners. In the level mode there may be slight twisting and the slides should not be moved until the frame is not flexed. Otherwise, the slides may be damaged.

[Junior Guru]

Larry,
Your routine is very similar to mine. Except mine follows with grab lawn chair and pop a cold beer! I'm usually need a few minutes of down time after driving several hours

Richard - is there a rule of thumb for how level the coach should be on grade/ground in travel mode before it's safe to put slides out?

Jason

[Richard]

Jason, unless the terrain is extreme, the three points for the HCV should put the frame in a relatively non twisted state. My rule of thumb would be if the ground looks like it has the coach in an awkward position, then I am either moving or leaving the slides in.

[Junior Guru]

Thanks Richard!

Makes total sense.

[lbrachfe]

Jason,
My wife won't let me put out the chairs until the bus is in living position.lolololol

[Yachts]

A note on mine is I always pull the sewer hose from the fuel tank bay before slides are extended because that door is a bus door and will not open all the way with number 2 slide extended

[arcticdude]

I would have thought having the frame level would be better for slide operation. While I understand the front hcv system, any irregularities in the ground will put a twisting stress on the frame, as the air pressures are equal- not the ground pressures. That being said, I would certainly go with what the factory says! If they tell you to dump the black tank and not the gray, put the left turn signal on and leave it in reverse when you move the slides, so be it!


Of course it may come down to air leveling versus hydraulic leveling. That would make a difference.

[Yachts]

Please don't put false information on the board.. Use the right blinker not the left !! Sheesh

[77newell]

Richard: Thanks for the clarity. I completely forgot about the single front HCV. I still have trouble wrapping my mind around all the variables, but I do trust the factory.