Re: Automatic Wheelchair Turntable

[nobody@xxxxxxxxxxxx (Dave Houston)]

I think your biggest problem will be to devise a thin turntable with a
bearing that can handle the weight. A zillion (± a few slew) marbles
sandwiched between two flat metal surfaces might work. For the drive,
bicycle chain (industrial chain comes in a multitude of sizes) fastened to
1/2 the circumference should be simple to work with.

How is the chair secured when the van is in motion?

"Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:

>I just got my Dad a wheelchair van with an electric ramp but we've hit a
>snag.  There's not enough room to turn the wheelchair around inside the van.
>If he goes in forward, he has to come out backwards.
>
>I toyed with some automatic guidance systems to make sure the backup
>procedure didn't run him off the ramp, but I don't think that's a wise
>solution.
>
>I decided that since there's almost a 4X4 foot flat area inside the van, I
>would take a 4x4 sheet of 3/4" plywood and make a turntable on the van
>floor.  When he transfers to the driver's seat, I want the turntable to
>automatically rotate 180 degrees to position the powerchair so that it will
>go down the ramp front first.
>
>I'm not sure how I would contstruct and power the turntable, however.  It's
>got to be as thin as practical - there's very little extra headroom in these
>types of vans and it's got to have some sort of autodetection of exactly 180
>degrees - probably some sort of limit switch.
>
>Should I rout a channel in the outside of the circular-cut plywood panel to
>run a belt?  That why I could mount a motor in the corner and still have a
>pretty low overall height.  Sort of how some belt-driven record turntables
>are designed.  I could also cover the ends of the belt that are likely to
>drag loose seat belts into the works pretty thoroughly with a motor mounted
>in the corner.
>
>Does anyone know if they make commerical turntables for this purpose?  As
>much research as we did on vans, lifts, ramps and options, it kind of floors
>me that we didn't realize there would be a "wrong way out" problem.  Just a
>reminder to always model things, even if they seem trivial.
>
>Well, any suggestions, inputs, discussion or ideas where to post for good
>feedback will be appreciated!
>
>(posted to:  comp.home.automation & alt.support.wheelchairs)