Guides, Slides or Posts. Alaskan Pop-up Camper shell construction question.

[Ted60]

I sure hope I'm in the right place.

I am in the planning stages of building a hard side, telescoping top camper shell on the M105 trailer bed that I've installed on my bobbed M35A2 deuce and a half.

I will be using bits of the steel bows that the trucks tarps now lays on as a frame work to lay on a steel roof. This roof portion will lift about a foot to give me 6 feet between the floor and the overhead. My wife and I are a bit on the short side and don't need much room.

My questions have to do with the guides, slides or posts that mount to the fixed hard walls and allow the top to "telescope" up and down straight and true. I can see that this guide/support/lock system has to be RIGHT, or it will be the bane of my existance.

I'm estimating that the total weight of the roof will be about 200 to 250 pounds. Being steel it should be rather ridged and strong. As I said, the total lift will be about 12 inches. Whatever I use, I don't much care if the guides contain a part or the total of the actual lifting mechanism. I can build in just about any thing to "lift" the top ... I need something that will guide it and supported it once lifted.

What method and materials do the Alaskan pop-up camper use? I've looked at a bunch of pictures and can only see things that look like drawer slides mounted on the left and right sides and the rear of the Alaskan's shell.

I have a couple ideas how to do this, but I would like to see what else has been done, or what might be available commercially so I don't have to totally re-invent the wheel.

Below is my old army mule, Henry. I did the bobbing on him about 3+ years ago. He's my daily driver and I've put over 15K on him. His primary mission will remain the same, medium duty, multi-fuel cargo hauler, but I would like to add "and semi-comfortable camper" to his MOS.

 

[Ted60]

I am also curious to know if the Alaskan type pop-up/telescope campers can be driven on the road with the top extended to full height. I would think that any camper with cloth sides could not.

 

[fluffyprinceton]

I can see that this guide/support/lock system has to be RIGHT, or it will be the bane of my existence.

What method and materials do the Alaskan pop-up camper use?

The Alaskan uses 4 hydraulic cylinders to lift the top, the lift section of the cylinders has a hole in it - you put a pin into it, release the lift pump & the top stays up resting on the pins as they settle on the top of the lower cylinder. The Alaskan guides are 4 simple steel male/female interlocking pieces. Too simple to describe...just two sections that capture each other. No bearings, not like drawer slides. They are mounted on the front & back bulkheads and keep the lift in line side to side - they work well. The front to back lift is more of a function problem as it's difficult to get the front & back cylinders to lift at the same rate due to the different hydraulic tube lengths and friction loads (one corner hangs up for some reason...) that are unpredictable. Alaskan has used (not at the same time) both flow valves and keeping all the tubes runs the same length to deal with the problem and both work OK.

The Alaskan uses a neoprene? rubberized fabric? strap seal that allows the top to lower section to have maybe a 1/2 inch of clearance. The point is the fit is loose & the Alaskan rarely hangs up - but the seal isn't very good & doesn't last more than a few years. SO...if you follow the Alaskan design, keep the top to bottom fit loose & simple guides will work fine - just copy their seal system. If you go to a more robust seal system with tighter clearances you should think long & hard about how to improve on the Alaskan.
I highly recommend finding an Alaskan & checking out their lift/seal system.

You shouldn't drive an Alaskan in the raised position at high speed without first trying it at a very slow speed...Another way of saying "NO WAY, but hey give it a try let us know what happened..." Moe

 

[Ted60]

Thanks for the kind reply Moe.

The Alaskan uses 4 hydraulic cylinders to lift the top, the lift section of the cylinders has a hole in it - you put a pin into it, release the lift pump & the top stays up resting on the pins as they settle on the top of the lower cylinder. The front to back lift is more of a function problem as it's difficult to get the front & back cylinders to lift at the same rate due to the different hydraulic tube lengths and friction loads (one corner hangs up for some reason...) that are unpredictable. Alaskan has used (not at the same time) both flow valves and keeping all the tubes runs the same length to deal with the problem and both work OK.

From my reading, I have learned that there are a number of lifting methods. They all seem to have difficulties from uneven lifting. I think I may have come up with a mechanical/pneumatic system that is simple and strong. My truck has a built in air compressor and storage tanks and its system is such that I can add to it if needed. But I know there are gods and gremilins watching over me that are laughing right out loud even as I type this, so I am keeping an open mind and open eyes to the problem of lift.

The Alaskan guides are 4 simple steel male/female interlocking pieces. Too simple to describe...just two sections that capture each other. No bearings, not like drawer slides. They are mounted on the front & back bulkheads and keep the lift in line side to side - they work well.

... The point is the fit is loose & the Alaskan rarely hangs up.

SO...if you follow the Alaskan design, keep the top to bottom fit loose & simple guides will work fine - just copy their seal system.

I was pretty sure that the Alaskan top to bottom fit would be pretty loose. Thanks for confirming this. If the fit was too tight any problems of flex or racking due to uneven lift would be a nightmare of jams and hangups.

I'm hopeing that someone could post a picture or pictures of the slides from the Alaskan design. Your discription makes it it sound like something I could replicate and build fairly simply and cheaply.

The Alaskan uses a neoprene? rubberized fabric? strap seal that allows the top to lower section to have maybe a 1/2 inch of clearance. The point is the fit is loose & the Alaskan rarely hangs up - but the seal isn't very good & doesn't last more than a few years. SO...if you follow the Alaskan design, keep the top to bottom fit loose & simple guides will work fine - just copy their seal system. If you go to a more robust seal system with tighter clearances you should think long & hard about how to improve on the Alaskan.
I highly recommend finding an Alaskan & checking out their lift/seal system.

I will ... and I'll be paying attention! The best seal might just be something that DOSEN'T seal or touch ANYTHING until the top is fully raised and locked in place. Something to think about.


Considering the lock pins, does the top portion of the Alaskan lock firmly against the bottom when its fully raised, or is it still kinda loose? I was planning to come up with a way to lock it tight for a number of reasons including allowing me to drive the truck short distances without having to to lower and re-raise the top ... like going to a store for supplies etc. ... and not destroying my camper.

On another note, Does anybody know the reason that the Alaskan Company built tops in this way?

I'm doing it to keep drag on the road to a minimum for better MPG's and stability in cross winds. Also for storage considerations.

 

[ripperj]

The Alaskan has thin pins that go thru the piston and rest on top of the cylinder in the full up position.
The Alaskan slides are simple but insanely expensive, I am rebuilding an old one and wanted to replace the slides ( more of a want than need) Alaskan quoted $600 for the 4 slides, this is not the hydraulics, just the drawer slide things. I would have never guessed they were that much. The original email from them said $150, and I thought that was even high, but it turned out to be $150 each.
The uneven raising and lowering is kicking my butt. My roof is no longer balanced because it's missing the windows and stuff, so it goes up and down really uneven, so it takes two people, one to pump the jack, the other to apply a load to the light end.

I would go with electric jack screws if starting from scratch ( upside down happyjac???)

Sent from my Z10 using Tapatalk 2

 

[fluffyprinceton]

On another note, Does anybody know the reason that the Alaskan Company built tops in this way?

It's an approach that was a pretty good idea in 1958...It's a better idea today due to the much improved sealants available. But the bulkhead with stringers sheathed with ply inside & aluminum outside design is unchanged & heavy for it's strength & you can't put a load on the roof (except by running full length bars supported by the bulkheads). A composite cored structure would be many times better...I really don't know why they've stuck with the design except they have a small market & get a decent price so why change? Give the basic Alaskan design to any competent boatbuilder and they'd come up with a vastly stronger & lighter camper...now at what price I don't know...
The lower section with all that rot prone 3/4 ply held together like kitchen cabinets...well don't get me started but it's more of the same (if they've changed their construction methods recently somebody should share that info as my direct experience is several years past)

When lifted the top is just kept from dropping by the small pins - the top can still move around & I wouldn't want to apply a up & down load on those small pins so that's why the Alaskan needs to be dropped for any real road travel. Also the cylinders would be stressed side to side so that might be a problem. I do think the "drive to the store when lifted" is not a real world problem, it's just not a big deal to lift & drop - but yes it might come in handy...

The beauty with the Alaskan system is it's simple & hard to screw up. In a 8ft camper even an obvious back to front slant when lifting isn't a problem - mine never really lifted straight & sometimes when lifting on uneven ground it would bind a bit. The solution was to push up on the lowest corner - not as hard as it sounds since you are just evening out the hydraulics not actually lifting the top, anyway I always got it up & always got it down over my 18 year ownership and the camper was about 16 years old when I bought it and no work was ever done to the lift system...You could as of 8 years or so ago buy the lift system from Alaskan but it wasn't cheap.

The problem with the Alaskan system are the seals - they just aren't very good in my experience - both in longevity and the mosquitoes getting in around the seal edges where they are cut to allow the lift guides. Any solid seals would make for a tighter fit & demand a better lift synchronization Under All Conditions because it's that one off camber camp in the snow that will be a stuck top nightmare. I always thought brush seals would be better than the straps but I never tried that approach. Moe

Here's a shot of the "female" guide, the "male" guide is in the upper section. The female edges form a 1/2 round - the male section edges are captured within the 1/2 round. The male section has some sort of offset from the camper body so it rides cleanly - I don't remember the clearances or how the offset was arranged...

 

[Ted60]

Thanks for the foto, Moe.

Your discription combined with the picture make the Females look almost like the tracks used to guide a horizontal-sectioned garage door, remembering that the wheels on the door ride on the inside of the track.

Very interesting.

On another note ... BRUSHES. Why not? Sounds like a pretty good soloution.

Thanks again.

T

 

[dwh]

For quick and cheap and strong, check out how westyss did his:

http://www.expeditionportal.com/forum/threads/48351-out-with-the-old-in-with-the-new

He used short screw jacks, wired with a control box with 4 switches. His top fit is fairly tight, but with a bit of slack, and he can manually slant the top this way or that to make the rain run off the way he wants.

There are few things in the world stronger than screw jacks. If you used solidly mounted jacks with both a push and pull rating, you would be able to leave the top in whatever position you want and drive around with it like that, since whenever the jack isn't turning - it's locked in position.

FYI: most of your swing gate screw jack "gate operators" for electric gates run on 12v DC. They run from a battery so they'll work even when the power is out. The battery just has a trickle charger on it that keeps it topped off. If you look at regular web sites like Home Depot, they charge outrageous prices for gate operators - and they usually only sell complete kits. Check around your area - there is always a gate supply shop that the electric gate guys buy from. They'll usually have some decent 12v screw jacks for a decent price.