Joseph Gwinn wrote:
...
Which led to US patent 4,111,027 (to Bottomley), for the Magnabend
itself. Note that 4,513,475 says that the original hinge design of the
magnabend was not satisfactory, but does not say why.

I just read the MagnaBend patent* and found it very straight-forward,
especially compared to the complexity of the hinge. The original hinges
seem like a good idea: they aren't end mounted, so multiples could be
used, and they don't project into the axis of rotation.

I wonder how they were inadequate. The only shortcoming that occurs to
me is that during rotation there is an area near the front edge of the
bed that is opened up, leaving the material unsupported. It's a small
area, but maybe it's enough to allow distortion in the material.

I'd really like to know, 'cause those hinges would be so much simpler to
build.

Bob

* - reading patents is so much easier with 2 monitors. My big one has
the drawings, full screen, and the smaller one the description text. No
scrolling up and down 'tween text & drawings.