Extending slide room causes air bags to deflate

[FIRE UP]

Well Gang,
As I've always stated, I'm always learning things on this site. In the OPs original first post, he's mentioning at least two issues. One, he's talking of "movement" as the coach settles. He didn't really stipulate between "body or, wheel movement". He's also talking about air "escaping" as he moves a slide out and, so much so that, eventually in a short amount of time, the coach has settled to the axles, without the use of the "dump" valve, in the HWY operational panel. Hmmmm.

Well, in reading many of your posts, I've now learned something. In the design of some of these suspensions, it appears that there is some geometry and force that takes place, as the coach changes from a normal ride height, to a settled, parked position. And, it appears that there is much more "body" movement in some, than others.

As stated, we have an '04 Itasca Horizon 36GD with the C-7 330 CAT. To date, we've (both the wife and I) have witnessed it drop, several dozen times during the leveling procedure, (both being out of the coach while the HWH system is on "auto-pilot") and while I've not really placed any type of proximity gauge to the front or rear bumpers to actually "gauge" any forward or rearward movement, neither one of us has ever noted any of that type of movement during the release of air, from the air bags, prior to the starting of the jack system. All we've ever noticed is, the coach goes straight down or, when airing the bags back up, the coach move straight up.


Now, if some of your coaches move as much as "6 inches" during that operation, to me that's amazing. Apparently it's all normal to you since you say it's been doing it for ever. Now, whenever the operation of leveling is brought up or, talked about on here and people have issues, many times people tell folks to make sure the parking brake IS SET, prior to operating the leveling system. Well, on the HWH system we have, the HWH panel will not initiate anything UNTIL the PARKING BRAKE IS SET.

There is a an interlock built into that system. And, if by chance, the parking brake is released prematurely, that HWH system automatically goes into the "Store" mode which, will air up the bags and, retract the jacks.

Now, I'm still interested in why his slide vs Air system is having its dilemma.

[Ray,IN]

This afternoon I was perusing the Winnebago forum and discovered an Oct. post(since lost the link) from a guy that stated that same settling when extending the slide, so apparently my MH is not weird.
The movement I spoke of is coach movement,ie: rolls a few inches. I'm really curious how that happens when the parking brake is set???? Although it is not unique to Winnebago, since my friends Newmar Essex on Spartan K3 chassis does it (he's the one who told me to watch for it).
Apparently it's time for me to phone both Winnebago and Spartan with this "rolling a few inches" question.

[palehorse89]

Ray, the rear air suspension does not go straight up and down, with the rear axle being mounded solid to the frame in the front and in the rear nothing but air bags and shocks, so when it airs up it does not rise at 90 deg. to the chassis, hench wanting to move the chassis a bit forward and it can because the front wheels can move.
Here is some reading on this: http://www.myrvparks.com/forums/showthread.php?t=833

[jerichorick]

Originally Posted by palehorse89

On the Spartan chassis when you pull the air brake truttle valve it "only" sets the brake chambers on the rear axle, not the rear and front wheels! If anyone has been setup in a unlevel site and your front wheels are off the ground a bit, it makes it easy to clean them as you can turn the wheel!
The front wheels are able to move and roll. Iam not sure about other chassis mfg's but just like on semi's, brakes set(rear axles on tractor) and the trailer wheels, not the steer axle wheels.

Yeap. Front wheels will move in that case. But I don't want that coach if any portion of the chassis moves forward or backward of back (locked) wheels! I never heard of a tandem coach.

[jerichorick]

Originally Posted by Ray,IN

This afternoon I was perusing the Winnebago forum and discovered an Oct. post(since lost the link) from a guy that stated that same settling when extending the slide, so apparently my MH is not weird.
The movement I spoke of is coach movement,ie: rolls a few inches. I'm really curious how that happens when the parking brake is set???? Although it is not unique to Winnebago, since my friends Newmar Essex on Spartan K3 chassis does it (he's the one who told me to watch for it).
Apparently it's time for me to phone both Winnebago and Spartan with this "rolling a few inches" question.

Ray, I understand the post Scott gave about the way the brakes work. I just don't understand the wheel movement you are describing on your Spartan chassis. Yes, we are just as confused and concerned as you. I just can't wait to hear the answer. The only thing I can think of is that the "slack adjuster" is not adjusted correctly on your brakes. Let's see what the experts have to say.

Rick

[Ray,IN]

Thanks Rick, I have read, then forgot the automatic slack-adjuster rods must be lubed when the chassis is lubed. Perhaps they are hanging-up from lack of lubrication.

[AFChap]

It would be interesting to hear a detailed explanation from Spartan, but I don't see any reason for the kind of concern expressed by Rick. The coach is not actually rolling. As palehorse pointed out, the chassis does not drop straight down due to the way the rear axle is fastened to the chassis. As also pointed out earlier, when the brakes are locked, the rear wheels are locked in place relative to the brake drum and the axle ...they are NOT LOCKED IN PLACE RELATIVE TO THE GROUND. Therefore, when the axle rotates slightly as the suspension drops, the wheels MUST move relative to the ground. The taller the wheel is, the more noticeable the movement will be. Try it with a toy axle ...lock the wheels on the axle and then rotate the axle. You will see the wheels turn in spite of the fact that the "brakes" are locked.

[jerichorick]

Originally Posted by AFChap

It would be interesting to hear a detailed explanation from Spartan, but I don't see any reason for the kind of concern expressed by Rick. The coach is not actually rolling. As palehorse pointed out, the chassis does not drop straight down due to the way the rear axle is fastened to the chassis. As also pointed out earlier, when the brakes are locked, the rear wheels are locked in place relative to the brake drum and the axle ...they are NOT LOCKED IN PLACE RELATIVE TO THE GROUND. Therefore, when the axle rotates slightly as the suspension drops, the wheels MUST move relative to the ground. The taller the wheel is, the more noticeable the movement will be. Try it with a toy axle ...lock the wheels on the axle and then rotate the axle. You will see the wheels turn in spite of the fact that the "brakes" are locked.

This is not my "concern" but a response to the original post. A 2" movement of the wheels is too much. If the back air brake locking brakes are allowing those wheels to move something is not right. The front wheels could move a little as the tension changes on the suspension with leveling and room extensions, true. But it can't be much. If the coach moves 2" after the jacks are set they could get damaged. That is a lot of movement for the length of the tubes.

If everything is working correctly all of this may simply be a misinterpretation of what is being observed and of no concern. It is better to ask than assume, even if the question is stated wrongly. With help from some friends things will come into focus.

I hope you now understand my comments better.

Happy trails,
Rick

[AFChap]

Yes, I understand your concern now. The movement is as the air dumps, BEFORE the jacks start down. There is no movement forward or back after the air is dumped.

[jerichorick]

Originally Posted by AFChap

Yes, I understand your concern now. The movement is as the air dumps, BEFORE the jacks start down. There is no movement forward or back after the air is dumped.

Have you called Winnebago about this? I take it this is something new? I can't see what you have at the moment. Is your chassis Freightliner?

In any case, I would use chocks under the rear tires when setting up. It would be tough to use boards to help level is a real bad spot.

I have never observed the type of movement you are having. I will definitely mark the parking spot before I dump air next time I set up. If I recall correctly I did read a caution in the owners manual about the potential for movement. Two inches may be within accepted parameters.(?)

PS: What is a "UA 40e"?

[palehorse89]

Just another thing here to ponder .......the drive shaft splined slip joint and what it does as the air suspension is raised and lowered, when the suspension is completely down the slip joint is completely retracted (factory travel specs.)and when aired up the joint extends, the transmission is not moving nor the rear end(except for raising the Chassis upward).......so what makes the spline slip joint move........Check it out..........

[AFChap]

Have you called Winnebago about this? I take it this is something new?

No, and No. It is somewhat new to the op, Ray, as he has not had his Ultimate very long. Mine has operated like this since new. We are talking about a Spartan Mountain Master GT/Winnebago semi-monocoque chassis. The front and rear members were delivered to Winnebago, and they inserted custom chassis members between the two ends. But the "movement" does not appear to be unique to the Winnebago version as pointed out by palehorse who also has a MM chassis under his Newmar.

UA is Ultimate Advantage. 40e is the floorplan. The Ultimate coaches (Advantage and Freedom) were Winnebago high end diesel models from 1999 -2004. There were built in a dedicated plant in Mason City IA not far from Forest City. I believe they converted the plant to Class C models after 2004.

[Shoptech]

The movement is because most air suspension systems use "trailing arms" to locate the axle,the axle moves in an arc front to rear as it travels up and down. with the parking brake engaged and the air is dumped the coach will move forward and back as the air is dumped or filled.the rear tires don't roll, the coach body moves and the front tires will "roll" as the coach body moves. I see it on a regular basis in the shop.

[dsbike]

Originally Posted by palehorse89

Just another thing here to ponder .......the drive shaft splined slip joint and what it does as the air suspension is raised and lowered, when the suspension is completely down the slip joint is completely retracted (factory travel specs.)and when aired up the joint extends, the transmission is not moving nor the rear end(except for raising the Chassis upward).......so what makes the spline slip joint move........Check it out..........

The slip joint extends or retracts due to the transmission raising or lowering & causing the distance between the 2 to change. This does not necessarily mean the wheels move. the Body is raising up higher but the rear axle is fixed at the same location as when lowered. There are other parts that come in to account here such as u-joints on each end of the drive shaft to allow the angle to change slightly. Hope this helps you understand the physics in play here.

[palehorse89]

Originally Posted by dsbike

The slip joint extends or retracts due to the transmission raising or lowering & causing the distance between the 2 to change. This does not necessarily mean the wheels move. the Body is raising up higher but the rear axle is fixed at the same location as when lowered. There are other parts that come in to account here such as u-joints on each end of the drive shaft to allow the angle to change slightly. Hope this helps you understand the physics in play here.

The "entire" chassis moves as posted.........

[jerichorick]

If I can sum this up. The movement is normal. As the chassis settles the wheels move.

Ok. I understand what you are saying. The history of the coach build is great information and helps me understand this some. But I am still not certain if the wheel movement is limited to the front axle, or do both axles see this movement? I just can not find it 'normal' for the back wheels to move. I have been confused about this point throughout this discussion. I may have missed the answer in one of the other posts.

Rick

[Ray,IN]

Rick I will ask tomorrow why this happens. We'll be at Camping World to have the step-cover repaired. The Technician assigned to our MH has 18 years experience and shares information freely, he's the one who replaced all the step-cover parts. The previous owner had removed all the working parts and simply installed a manual air valve to move the cover(caused cover to shoot out quickly), which could be dangerous to our grandchildren if they moved the switch while standing on the steps.

[jerichorick]

Originally Posted by Ray,IN

Rick I will ask tomorrow why this happens. We'll be at Camping World to have the step-cover repaired. The Technician assigned to our MH has 18 years experience and shares information freely, he's the one who replaced all the step-cover parts. The previous owner had removed all the working parts and simply installed a manual air valve to move the cover(caused cover to shoot out quickly), which could be dangerous to our grandchildren if they moved the switch while standing on the steps.

Thanks Ray. And protecting our grandchildren is a very good thing! We will spend Christmas in Seattle with ours. We are flying out of DWF. I pray we don't have another ice over.

It is of great interest to me what CW tells you about the movement. I just know this will come up in another discussion.

[dsbike]

Originally Posted by palehorse89

The "entire" chassis moves as posted.........

I understand the movement of the "Entire" chassis as posted. My reply was why the slip joint on the drive shaft goes in & out which in turn lengthens or shortens the drive shaft. As I also posted this may or may not be related to the movement of the vehicle. If the drive shaft is short enough you would never see the movement, but if it is a long shaft then in turn you will see movement in the vehicle.

There has been several posts here that explain the movement of the front wheels when the coach raises or lowers on the airbags. The rear axle swing arms are pivoting allowing the coach to move but the rear wheels stay in same position. After the previous explanations I agree & I understand how this is happening.

[Ray,IN]

No answer; the technician who I intended to ask about the coach moving arrived after we dropped off our MH and left for a Dr's. appt before we returned to pick up our MH. Sorry guys, I dropped the ball; and he does not work Saturdays, so I'll have to Phone him later.