Thanks for the comments. I considered them carefully and here are a few additional thoughts...
“I think the images are computer renderings. It makes me wonder if the designer ever made a prototype.”
Fully agree, as I said "
It is not clear if the plans are for fabric or solid sides, or if the author actually built one.”
I surely wouldn't want to spend a night in an unvented box without windows. ...
Where do you suppose water will end up running down the walls?
Agreed, but again, it is not clear what his full plan is. The image is just part of an ad. I would want more detail before purchasing a plan, but $10 is pretty cheap.
If what you want is a canvas sided pop up, they are many good ones available ..... The types of lifting mechanisms you see in pop ups evolved because they work. If there was a simpler, cheaper, or more reliable way to do the job, I think you would see the commercial producers use is.
Yet interest in DIY solutions persist! What if you replace “canvas sided pop up” with “tear drop”? I suspect the list of reasons many of us choose DIY over commercial is pretty long.
The early tent trailers with solid tops that I remember used external bi-fold struts. Today, most are larger and use 4 hidden telescoping struts with three sections each. With all the struts, cables, shafts and cranks, the new ones are far more expensive. Can it be that commercial designs are largely driven by what justifies a bigger price tag (profit)?
Further, is the most appropriate solution for commercial production the most appropriate for DIY? Twenty-five years ago I built an experimental 3 section PVC portable antenna pole that used the same techniques as the expanding struts. I was actually surprised how well it worked, but rejected it because it depended on a tight cable to stay fully erected (it was difficult to lock the sections 10 & 20 ft up in the air). Frankly, I did not find it simple, cheap, or reliable. I have the same attitude toward using them for a trailer. If you find commercial struts at all, they are probably replacement parts with very limited size and load selection. And I doubt anyone will consider them cheap. Without access to special metal working tools, they are not simple to fabricate. And I question how reliable/maintainable they are. What do you do when the cable comes off a pulley wheel that’s internal to a strut which is internal to the trailer wall?? How easily can you “jerry-rig” a fix at the campground? How do you fix a bent strut (will the sections ever slide smoothly again?)?
“The ropes or cables they appear to use won't guarantee that the top won't tip side to side as its raised.”
Yes, unless he has sliders around the poles attached to the top (not clear in figure). For a trailer with fabric sides/ends, that is exactly what I anticipate. Going up I would expect the side near the crank to lead the other side. Going down might reverse the tilt. I can imaging at least 2 ways to limiting tilt, but why is that important?? The early commercial tent trailers were opened by fully raising one end first. A tilted roof during erection was “part of the plan”.
For a telescopic top, the top can not tilt much until it is nearly raised off the base, but it can bind (jam). That’s one reason I said “
...it might be a reasonable alternative for a tent-side solid-roof arrangement.” I didn’t intend that as a strong endorsement.
“It's easy to design things in CAD that don't work as well as you thought they would or are difficult or impossible to actually build. I'd really like to see a prototype constructed and used for a time to work the bugs out of the design.”
Yes, I fully agree. I would not have posted this for lack of information, but decided his unusual lift mechanism was adequately described by his CAD rendering. As such, I probably picked a poor title.
“I am a big fan of lifting tops! Travel small, camp tall!
I love seeing the different approaches.”
Fully agree, that’s what I see this thread as being all-about. I posted this because I found the lift mechanism “unusual” - not totally unique or one of great genius, but interesting. I tried to point out advantages, limitations, improvements, and issues some builders might want to consider.
BTW - Love the wrap-around screen. Great work!