Simple Adjustable Hinge Design

[ChrisDanger]

I'm looking to cheaply manufacture an adjustable hinge, to fix a wheelchair footplate upright to the main frame. Something like the Variloc hinge below looks great, but is expensive to buy, and is complicated to reproduce (with many small internal parts).

Does anyone know of some way to provide a similar level of adjustability with a simpler joint? I've spent some time looking around for inspiration but have not found anything really.

 

[natepiercy]

A slot with a bicycle seat clamp?

 

[rb1957]

could you make it work with maybe three parts ?

Maybe a triangular pin with different slots/cut-outs in the two arms so that they align at different angles ? A problem would be controlling the two arms with the pin out (to re-position the angle between the arms

another day in paradise, or is paradise one day closer ?

 

[EdStainless]

How often are you going to change it? If not very often then I favor a design that has mating teeth on the two surfaces. You could clamp it with a small quick release (like for bike seat posts) and it would then be adjustable in steps, depending on how many teeth there are.

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P.E. Metallurgy, Plymouth Tube

 

[ChrisDanger]

It's supposed to be for adjustability as well as folding the footrests away when getting out the chair. So it will see pretty constant use.

 

[rb1957]

what if there was a cable running from one leg out to a pin in the other leg ?

with a small spring it'd always be in tension, closing the two arms.

another day in paradise, or is paradise one day closer ?

 

[ornerynorsk]

Elesa just began manufacture of a toothed washer arrangement that would accomplish the same result, without the push button convenience however. Hans-Georg Pieper company in Germany also makes one similar to the variloc, much less expensive, that is used extensively in the DME world.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[ChrisDanger]

Excuse the ridiculous example image, but the hinge will replace the bend circled below. We're looking at folding the footrest back when getting out the chair (and for it to stay there when not in use) as well as allowing a range of positions for the user.

 

[ChrisDanger]

Hi ornerynorsk,

Do you have a link to that Elesa hinge? One of the latest concepts I put together also used a tooted element.

 

[rb1957]

simple cable ?



another day in paradise, or is paradise one day closer ?

 

[ChrisDanger]

Hi rb1957,

Sorry, I don't quite understand what you mean. Do you perhaps have an example?

 

[rb1957]

how about this ...

another day in paradise, or is paradise one day closer ?

 

[hendersdc]

The first thing that came to mind for me was a regular hinge with a retractable pin that mates to holes at preset angles. This kind of mechanism can be found on all sorts of exercise equipment, this picture shows an example with it in use in two places.

 

[ChrisDanger]

Hi rb1957, Thanks. Sorry, I didn't actually see the attachments until now. I'm not used to this site.

The footrest is likely to see all kinds of forces (there will be anti-tip wheels, and of course a body-weight force). I don't see how this concept will support the weight, unless I'm looking at it incorrectly.

 

[ChrisDanger]

Hi hendersdc, Thanks. Something like that was one of our first ideas. We were looking for something more compact, but it's good to get a reminder in any case.

 

[Sparweb]

I second Nate Piercy's suggestion. (the first reply).
Not only does the bike-seat-style clamp allow pivoting through a large angle, the tightening screw can be replaced with a lever-lock which allows adjustment with no tools (like removing the front wheel of a bicycle).
In fact, the quick-release bike seat is becoming common on bicycle seats now, as the seat, too, becomes an item to steal off the racks.

STF

 

[ornerynorsk]

Could not find those elements on Elesa's website. We got samples from our salsman. I'll try to find out some part numbers and such.

There's also these, but they may not take the moment force:

https://www.rockwestcomposites.com/accessories/other-joints?p=2

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[EdStainless]

Perhaps a ball detente design with a cam lock center bolt.

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P.E. Metallurgy, Plymouth Tube

 

[berkshire]

You might also look at the push button Adjustable hinge on the " Little giant" folding ladder .
B.E.

You are judged not by what you know, but by what you can do.

 

[ChrisDanger]

Great. Thanks for the responses I've drawn up a few more concepts from the ideas.