hinging folding bed couch mechanism idea

[baliboy]

Greetings,
I am fitting a 1983 Toyota Coaster bus with beds for 6 and a few other items. I will be using stainless steel and wood. I am looking ideas, photos, diagrams, or keywords that detail how a bed frame could be raised and lowered above another lower bed frame. I plan to use gas shocks, as found on the rear hatch of automobiles for lift assistance, but am boggled with how the hinging/folding/lever/slide/scissor mechanisms would work to keep the upper bed horizontal as it raises and lowers. My concern is that the upper bed will catch on the walls if it isn't perfectly horizontal as it is lowered/raised.

Here is an animation showing the beds moving from sleeping position to sitting and back for one potential bed configuration on the interior of the bus. http://youtu.be/XLcv57sUZUI

Will post earlier conversion photos of the bus if there is interest.

[beemerphile1]

HappiJac makes bed lifts. You could buy or maybe just look at them and get some ideas.

[baliboy]

This would work, but would either have to sit in the middle on each side of the upper bed AND be wide enough to support the 2 meter long bed, or have 1 at each corner thus adding a lot of weight.

[baliboy]

DrewE thank you for your reply. This is what I'm looking to find, interesting ideas that are different from what I am imagining. I do know what you're talking about on drafting boards. Thank you for taking the time to sketch and upload. I can visualize a cable solution.

The lead screw system would be great as it is powerful, thus able to lift with a person or gear on the bed, and I like the idea of a switch that would toggle the bed position, but am concerned about safety. So with lead screws there would have to be torque/pressure sensors to prevent an accident, and most all of these items are very hard to find here in Bali unfortunately.

One more thing is that I must use wood or 316 stainless steel to prevent costly maintenance, as this bus will be at the beach its entire life.

[DrewE]

One approach would be to use an aircraft cable at each corner vertically, and cris-cross them in upper (sliding) bed to the diagonally opposite corner using pulleys/rollers.

Here's a very quick, rough diagram of one of the four cables; repeat at all the corners for the others. Some care in cable routing needs to be done at the middle so they don't all rub and chafe too much; either offsetting them by clever pulley angles/cable positions or routing them through a tube of some sort would probably be practical.




Similar arrangements are (were) used on manual drafting boards with built-in traveling straightedges, and probably in many other applications. You would want some sort of turnbuckle or other means for adjusting the tension in the cables and, indirectly, the level of the platform. It's not necessary to have them under tremendous tension.

I'm sure there are many other solutions that would also work. For power operation, a scheme of interconnected lead screws seems to me fairly straightforward and practical.