But, ours is a wood frame bed with a plywood support and two wood rails on the walls at the foot and head of one bed ( the one without storage above it..too bad would rather have had more storage...)
Well it turns out this is the earlier style bunk and was orderd for this trailer, as it is written on the original order form. Cost $52.00
It sits on the rails and latches to the ceiling when not in use.
No hinges were left on the rails and I puzzled over this.
I finally discovered it could work with a pivoting hinge, and headed off the HD to find some.
The only thing I found there were two brass hinged lifts that were small enough to fit on the rail, and let the bunk rotate up to be latched. Not wanting to order online I went ahead with the two hinges.
After some measurement and creative tool use involving a socket set and phillips bit, I was able to install them.
Side benefit!! the bed now will pull out a bit for latching and then slide back to sit on the rails for more evenly distirbuted support. Unlikely that any child will sleep in this on my watch, and it is rated for under 100 lbs anyway. But it looks cool as heck and will be great to throw stuff on (like my ever present guitar) when we park.
bunk up latched
bunk down for use
Brass lift hinge