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Old 11-25-2015, 09:25 AM   #21
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Originally Posted by Oaklevel View Post
Just level then put the slides out It will be close enough to level for government work...... do not have to over think this thing.


Just.....
My thoughts too.
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Old 11-25-2015, 10:59 AM   #22
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Originally Posted by Papa GLS View Post
If you level unit & put down stab. jacks before putting slides out, shouldn't it remain fairly level? Just depends on how much sag is in the slides.
Not if the ground is soft. Those slides weigh quite a bit. Especially if you have 2 or 3 on one side.
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Old 11-25-2015, 11:17 AM   #23
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Not if the ground is soft. Those slides weigh quite a bit. Especially if you have 2 or 3 on one side.
How does the mass change from being inside the camper and then being extended for the slide? If you do a free body diagram of the mass involved you would see there is no change in the total mass of the unit. Now the bending moment is different on the frame but not on the stabilizer legs and jacks. you still have the same downward component on the legs and stabilizer jacks.

Now when setting up a trailer/motorhome on a soft site or hard site consisting of gravel/concert pad; I would always recommend pads 1x12x12 plastic or wood blocks of similar size under the stabilizer and jack legs. This way you will spread the downward component (load) of the mass in the trailer over a larger area.

I use two 4X4x12 inch wooden blocks under each 8" round pad on my unit when setting up. I have seen the blocks sink a little bit but the load is spread over a larger area. I also place the trailer tires on two 2X8X6' long boards when I am on dirt or grass. I have never seen the blocks sink any farther when the slides are extended.
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Old 11-25-2015, 11:25 AM   #24
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Originally Posted by Iwritecode View Post
Not if the ground is soft. Those slides weigh quite a bit. Especially if you have 2 or 3 on one side.
Yep.
If all you ever camp on is a concrete pad or a very hard packed gravel/stone site, then the unit likely will stay pretty much level after putting out the slides.

But just as Iwritecode said, if you do any boondocking or get a grassy sod site and have a rig with two big slides on just one side, it will change a full bubble out of level when you put the slides out. (unless you compensate to begin with)

I don't think that is overthinking anything. Pure common sense.
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Old 11-25-2015, 11:38 AM   #25
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How does the mass change from being inside the camper and then being extended for the slide? If you do a free body diagram of the mass involved you would see there is no change in the total mass of the unit. Now the bending moment is different on the frame but not on the stabilizer legs and jacks. you still have the same downward component on the legs and stabilizer jacks.
I'm not an engineer but I don't think mass has anything to do with it. It's simple physics. Hold an 8' board straight up on the air vertically. Easy right? Now hold that same board straight out horizontally. It will pull downward. It's the same with the trailer slides. The fact that the slides are no longer directly over the stabilizers causes more downward pressure to be applied to them. In essence, the slide becomes a lever with the edge of the trailer being the fulcrum.

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I also place the trailer tires on two 2X8X6' long boards when I am on dirt or grass. I have never seen the blocks sink any farther when the slides are extended.
I have. Just a month ago I had to help jack up a trailer and put another board underneath it because it was leveled before the slides were put out.
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Old 11-25-2015, 11:57 AM   #26
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Originally Posted by Jim34RL View Post
How does the mass change from being inside the camper and then being extended for the slide? If you do a free body diagram of the mass involved you would see there is no change in the total mass of the unit. Now the bending moment is different on the frame but not on the stabilizer legs and jacks. you still have the same downward component on the legs and stabilizer jacks.

Now when setting up a trailer/motorhome on a soft site or hard site consisting of gravel/concert pad; I would always recommend pads 1x12x12 plastic or wood blocks of similar size under the stabilizer and jack legs. This way you will spread the downward component (load) of the mass in the trailer over a larger area.

I use two 4X4x12 inch wooden blocks under each 8" round pad on my unit when setting up. I have seen the blocks sink a little bit but the load is spread over a larger area. I also place the trailer tires on two 2X8X6' long boards when I am on dirt or grass. I have never seen the blocks sink any farther when the slides are extended.

The mass doesn't change, Just the amount of force where the mass is supported when the slides are extended. (leverage point)

When the slides are all in and the stabilizers are all extended, the mass is pretty evenly supported by all 4 stabilizers because the mass in pretty much centered. When you extend the slides (again we are talking mostly about a rig with just slides on one side) the force applied to the stabilizers on the slide side increases and the force on the stabilizers on the non-slide side is decreased.

Think of it this way... climb in a shopping cart/buggy and sit in the basket.
All your weight is supported evenly on the four wheels and you don't tip over.
Now... climb back out and hang off one side of the cart and see what happens. Same mass, different leverage point.
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Old 11-25-2015, 04:00 PM   #27
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I'm not an engineer but I don't think mass has anything to do with it. It's simple physics. Hold an 8' board straight up on the air vertically. Easy right? Now hold that same board straight out horizontally. It will pull downward. It's the same with the trailer slides. The fact that the slides are no longer directly over the stabilizers causes more downward pressure to be applied to them. In essence, the slide becomes a lever with the edge of the trailer being the fulcrum.


"Mass is weight in engineering terms". That's called bending, the load is still transferred to the legs/stablizers.


I have. Just a month ago I had to help jack up a trailer and put another board underneath it because it was leveled before the slides were put out.

And I bet there was frame twisting going on also.
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Old 11-25-2015, 04:20 PM   #28
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The Cedar Creek in my signature is our third 5er and I have never in all of the time we have camped been out of level; when the slides have been extended. Before this we had pop-ups.


Our first 5er; a 2006 AMERI CAMP had one full length slide on the Driver Side. This was equipped with a wheel master level indicator. We would extended the legs/stabilizers and boards under the wheels. Blocks where used under all legs and stabilizers. Bubbles where never off fore aft or side to side when the one full length slide was extended.


Are other 5er was a Cougar with three slides this to was level before extending the slides. In fact the owners manual indicated that the unit should be leveled and stabilizers extended before the slides were extended to prevent frame twist.


Now our Cedar Creek has to have all six legs extended and the trailer leveled before the slides our extended. With this unit the trailer will self level with just a touch of a button. When the trailer goes through the self leveling procedure the trailer will dip and extended to achieve level. The slides can not be extended at all during this process or the frame will twist and bend.


So in my humble opinion if the trailer goes out of level due to slide extension. Than the unit is not balance correctly and is over loaded on one side. Because you are causing frame twisting by jacking up after the slide is extended.
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