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#p948916Binding problem is described in this append
http://www.tnttt.com/viewtopic.php?f=55&t=46804&start=270#p958950If I'm not mistaken, BUB was the first foam/fiberglass build on this site (as well as one of the earliest telescope pop ups).