Pneumatic Camper lift build

[starleen2]

Interesting video of pneumatic cylinders at work to raise the roof of a small camper.

thinking of using the same system to create a small Hi -lo camper build?

[WizardOfOdds]

Thanks for posting an interesting find. Yeah, I see a pneumatic lift system being pretty simple to build. And it doesn’t take high pressure (only a bit over 20 psi in 1.25 inch diameter pistons should raise a hundred pound top). But I am concerned about one key issue: While a (properly working) cable/strut system lifts each corner the same DISTANCE, a pneumatic system applies equal lift FORCE to each of the corners. Lifting one corner or end/side more than the other leads to "binding". I have enough trouble getting the lid off a telescoping cheese box without the top binding, so I have to believe it is a major problem with a trailer. You see some of that in the video, and the tighter the fit, the bigger the problem. Seems to me that a bigger trailer that collected a lot of dirt and grime might be a more practical test. As I recall “Coalburner” (and “Bonnie” who purchased it later) both had this problem with “BUB” (“Big Ugly Box”)

http://www.tnttt.com/viewtopic.php?f=5&t=19227&hilit=coalburner
Some lift notes start here:
http://www.tnttt.com/viewtopic.php?f=55&t=46804&p=948916#p948916
Binding problem is described in this append
http://www.tnttt.com/viewtopic.php?f=55&t=46804&start=270#p958950

If I'm not mistaken, BUB was the first foam/fiberglass build on this site (as well as one of the earliest telescope pop ups).

[S. Heisley]

...Very interesting. Thanks for that, Scott.

The trailer itself doesn't look very big. I'm guessing it's a 3'x?'x4' high (until raised). Too bad that there isn't more information on it.

[TheOtherSean]

That's pretty cool, but I think the WizardOfOdds has put his finger on the major problem. Without even lifting there will be binding. I think a person could ultimately calibrate so it does lift evenly, but it would likely be quite a chore and require periodic recalibration.

[H.A.]

T.

[starleen2]

Here is another - it does appear to have some binding problems and equalization of lift rates

[WizardOfOdds]

In the 2nd video, notice the top has no telescoping sides. The binding that I worry about is when the height of the top is about the same as the height of the base. In the 1st video, he overcomes the binding by "jiggling" the top when it stalls. This might not be so easy with a bigger trailer, but may be a good answer as long as the pressure does not build up too fast. (Once the top binds, more pressure will just lock it harder and make it more difficult to free). The binding can probably be minimized by making the top "loose fit" and use a lip to form the top/base seal.

[WizardOfOdds]

For what it's worth, here are two (more recent) related videos
I inserted direct URL links should the videos not play in-place

Note the use of plastic air bags on this lift
https://www.youtube.com/watch?v=FVeWsECl_rU


This one uses gas struts placed inside the steel rectangular lift legs
https://youtu.be/Manb83SD4Mo


and on this, it looks like he locks the gas struts (a trick I've used with homemade PVC struts).
https://www.youtube.com/watch?v=0paspNnErbw

[dancam]

Here is another - it does appear to have some binding problems and equalization of lift rates

Well that was interesting. I will have to look into diy air cylinders. Didnt know you could make your own.
I built a pop up foamie with the intention of being able to lift the top myself. Not that heavy, but its 5x12 and very ackward to lift. I think i will need some sort of assist system.

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[WizardOfOdds]

Well that was interesting. I will have to look into diy air cylinders. Didnt know you could make your own.

Take a look at these two videos, they are for an air pump and check valve, but very well done and will give you the basics you need for making struts.
Video on pvc pump https://www.youtube.com/watch?v=vaho7JSVS1I

One way valves https://www.youtube.com/watch?v=DG6own141z0

I think you will need some type of "lock-up" to keep things up over night.

I built a pop up foamie with the intention of being able to lift the top myself. Not that heavy, but its 5x12 and very ackward to lift. I think i will need some sort of assist system.

Check my comments above, I think you will find binding (even lifting) to be the major challenge. Let us know how you make out.

[dancam]

Well that was interesting. I will have to look into diy air cylinders. Didnt know you could make your own.

Take a look at these two videos, they are for an air pump and check valve, but very well done and will give you the basics you need for making struts.
Video on pvc pump https://www.youtube.com/watch?v=vaho7JSVS1I

One way valves https://www.youtube.com/watch?v=DG6own141z0

I think you will need some type of "lock-up" to keep things up over night.

I built a pop up foamie with the intention of being able to lift the top myself. Not that heavy, but its 5x12 and very ackward to lift. I think i will need some sort of assist system.

Check my comments above, I think you will find binding (even lifting) to be the major challenge. Let us know how you make out.

Thanks for those 2 videos! I will watch them when i get to some wifi. With the binding i planned to lift it myself anyway, i dont really care how much i have to help it, as long as i can get the top half up. I was also planning to have wooden supports holding it up once its all the way up and ratchet straps to hold it down while its up so it doesnt blow away.
I was going to attach some uhmw plastic to the 8 sides on probly the upper half so it slides better but to avoid binding i may not make them very tight and just use wedges or something once its up and ratcheted down tight.

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[WizardOfOdds]

Ohhh, and a limitation to keep in mind:

Except for the “spider leg” video, it looks like the strut is mounted vertically between the floor and the ceiling, therefore the increase in head room is the same as the increase in the strut length between fully retracted and fully extended. The fully extended length of a two section telescoping strut is always less than twice the fully closed length - often quite a bit less. That's because there must be some overlap of the sections (even when fully open) and end connections do not nest.

So if you build a strut with (say) 80% extension, then your head room increase can not be more than 80% for this simple configuration. Getting around this limit tends to add a bit of complexity. For small increases, the strut could extend a few inches below the floor, but large increases are often not so simple, (the “spider leg” system is an example). Notice the cable driven mechanical struts used on many tent trailers use three sections to achieve more than 100% extension.

[WizardOfOdds]

dancam, you might want to look over and perhaps contact the builder of this
. He at least comments how much he likes his lifts in this
http://www.tnttt.com/viewtopic.php?f=5&t=20356

So what worked well I want to keep? The pnumatic lifts are dabomb. Top goes up/down without any effort. It's nice to have air available at the campsite for air matteresses, bike tires, etc..

. His struts appear to be simple two segment units and mounted externally (because they are too long to be internal).

[WizardOfOdds]

The video below contains a segment that shows a home made lift on a pickup truck telescoping camper. It uses dual iron pipe rails with PVC sliders pulled by a steel cable via a chain drive crank. The portion of the video to watch is in the 6-10 minute range of the time bar.

This is not a pneumatic lift, but I decided to post it here to illustrate one cable driven alternative.