Hi Gary,

Try Nylacast I would recommend Aquanyl PA6/12 as it doesn't absorb water. No link to this company but I have used their material many times.

Good luck

Have you thought of fitting stainless ball bearings you can get 30 mm x 12 mm x 8 mm bearing for about £10.0 each from simply bearings

David

I'd just use Delrin on SS axles. It has very low water absorption and is dead easy to machine

How about lignum vitae as it is water lubricated.

I know a little bit about this 'cos I've been doing it since they gave me 12wks probation more than 30yrs ago.

The correct answer is to push the chair to poolside & tip the passenger into the pool whilst you both shout "BANZAI".

But, that is NOT the PC way to do it & definately NOT the way anyone other than the actual disabled person would want you to do it.

To answer your question in the closest way you would want it answering, the chair will be a pool specific one. Either as cheap as chips or a horribly expensive one (depending on the level of corruption in your local SS), so who cares about the lifespan of the wheelbearings? Certainly not the taxpayer, who doesn't get a say in such matters.

No need for lignum vitae or anything home-made. Try searching for 'Waterproof Bearings'. You can get plastic ball bearings specifically designed for low maintenance in wet environments. They're also resistant to most chemicals.

I like Mick's BANZAI suggestion, and you should take up his kind offer to be test-pilot. Please video his Kamikazi off the high-board so we can all improve by watching Charity in action.

Dave

Have a word with Igus, very helpful on material selection for their bushes and not expensive. Their catalogue is good if you can navigate your way through it.

Presumably Staimnless for the shafts and housings, and then a composite, (or could sealed , 2RS, ball races be used?

I liken the suggestion of lignum vitae. Water lubricated, has been used as a thrust bearing for ships propellor shafts for many years. Don't use it as a bouyancy aid, denser that water!

Howard

Dry bearings would be the way to go.
Because any kind of lubrication will upset risk assessment bods.oil or the hint of a risk of oil ib the pool .Even PTFE built into plastics .. would be called a lubricated solid..just avoid that discussion
So choose a self lubricated solid. Though avoid leaded bronze or similar…

Edited By jason udall on 05/10/2018 21:36:00

Lignum Vitae, very old lawn bowls, stick to the plastic bearings on 316 stainless shafts, make sure all metal parts are stainless or plastic, and probably best to over engineer the chair as they can have a rough time from some staff, or patients.

There was a Kiwi bloke Rob Buchanan  making low priced plastic wheel chairs that were suitable for being immersed in salt water. Ron set up a Charitable trust called MEND, I don't know if the e-mail address is still ok,

mend@voyager.co.nz

Ian S C

Edited By Ian S C on 06/10/2018 11:00:26

I'm sure you've thought of this, but make sure the tubing is open ended and can drain easily. You don't want it floating away but at the same time you don't want water sitting in it if it's left unused for a week or two.

Neil