Axles and tires for power wheelchair

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I've got a scooter that has a 11/16" keyed axle but most replacement wheels I can find on Ebay have a 13/16" hole. I seem to recall from machine shop in 1969 that a motor shaft can be fitting with a slip-on "collar" (not sure of the right word) that would add to the diameter of the shaft/axle and make the wheel/pulley with the larger opening fit more snuggly.
Any suggestions on where to find such a device or other means to use a slightly oversized wheel opening on the existing axle? From what I understand the manufacturer "heavied up" the axle by an 1/8" because they were getting bent. I've found a lot of replacement wheels (looking to replace the tube type that's on there now with foam filled puncture proof tires) and almost every wheel I've found on Ebay is the large hub size.
Thanks in advance for your input!
--
Bobby G.



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Robert Green posted for all of us...
And I know how to SNIP

The key in the axle is the problem. I suppose a machine shop could make a bushing with key-ways in it but economical feasible IDK.
--
Tekkie

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wheels

shop

sure

make

I've seen the item I am looking for. It's a springy tube with a channel cut down the entire center so that it clips onto the undersized axle/shaft. The channel gives the tube the ability to be undersized enough so that spreading the channel open slightly when installed makes it stay on pretty tightly. The channel also serves to allow keyways and setscrews to do their job. In fact, without the keyways/set screws, the add-on tube would just freewheel.
Now I just need a name/source for the slotted tube I am describing. We used to use them in machine shop when mounting pulleys on a shaft that was too small to mount it securely. In 1969. (-:
--
Bobby G.




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wheels

sure

make

http://www.skf.com/us/products/vehicle-aftermarket/automotive/specialty-parts-and-programs/speedi-sleeve-shaft-repair-kits/index.html
SH
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Robert Green wrote:

It's called a bushing .
--
Snag



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On 7/17/14, 2:58 PM, Robert Green wrote:

McMaster-Carr might have what you describe, but not in your size.
Check http://www.mcmaster.com/#standard-reducer-bushings/=svqshr
They also have an extensive list of wheels. Take a look for what you need
http://www.mcmaster.com/#wheels/=svqu2i
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wrote:

But what's wrong with finding the right wheel? The bushings generally wear quickly when pounded around on a power chair
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Wheels. It's cost. I got some new foam filled tires and rims for less than 1/5 the price of just new tires ones on Ebay. Factory original equipment for these items are outrageously priced because as "durable medical equipment" the list price is set super high to accommodate all the discounts they give to various insurers.
The chair doesn't get a lot of use so I'll take my chances with the bushings. If they fail, I'll go to plan B. (-: It looks like I can take a standard flanged bushing and cut a channel in it with a cut-off tool for the key. Since the drive force is mostly routed through the keyed slot I suspect bushing won't take too bad a hit in this instance.
Thanks for your input!
--
Bobby G.



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shop

http://www.skf.com/us/products/vehicle-aftermarket/automotive/specialty-parts-and-programs/speedi-sleeve-shaft-repair-kits/index.html

The adapters are more than I paid for the wheels! Gotta go with something a little cheaper. Might just try to find some 11/16" ID x 13/16" OD stainless steel tubing and make my own.
--
Bobby G.




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On Thu, 17 Jul 2014 21:32:17 -0400, "Robert Green"

I've worked on a few where even the original wheels got "hogged out". The chairs are heavy, and the whole power train is unsprung weight, so the bumps are taken up by the wheels and axles. I'd be likely to grab a couple of hubs and bolt on some trailer wheels. Get 3/4" hubs and bore them to fit broach the keyway, fit it up and then put a couple tig spots on it for good measure, and bolt on the rims.
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Robert Green wrote:

Maybe roll up a pair out of .062" stock ? You'll also want to increase the key height by that same amount , help prevent it from rolling in the keyway .
--
Snag



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On Thu, 17 Jul 2014 21:32:17 -0400, "Robert Green"

Birth control! I don't think that will help in your situation.
If bushing isn't exactly the word you want, call a real machine shop and ask them. Call 60 to 30 minutes before they close. That's when they may have finished their work for the day and have time to talk, although maybe that's more for office people.

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I've been noticing that all the fixes I've found are for much larger shafts.

I'm sort of stuck with what I've got now. )-:
I'm still going to look for the things we used in machine shop way back when that clipped onto the motor shaft and had a slot for keyways or set screws.
Thanks for your input!
--
Bobby G.



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On Friday, July 18, 2014 4:18:28 AM UTC-4, Robert Green wrote:

When I worked in a manufacturing plant, we didn't use keyways to attach gears.
The problem with a keyway is the gear can only go on the shaft in one position. Sometimes that is okay, but sometimes for timing or other purposes you need the gear at some other angle
So we would bore out the gear enough to get a Ringfeder in between shaft and gear.
http://www.ringfeder.com/en/International/Products/RINGFEDER/
I don't see why it wouldn't work for a wheel as well. They certainly handled all the torque a gear needed.
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<stuff snipped>

take a

the

Spoken like a man with access to a machine shop! (-: Wish I had access or even a Unimate mini lathe (which I've wanted since I took my first machine shop class in 196x.
The wheels are on their way. Once I get them I'll be able to better assess the situation. Right now I am hoping the seller measured wrong and they fit perfectly. If not, I'll find bushings somewhere. This is a very lightly used unit that mostly runs on paved parking lots and building floors when my knee's too blown out to walk.
If it was an ATV or even a bariatric wheelchair I'd be in 100% agreement with you. They take a pounding because of rough terrain in the first instance and substantial weight in the latter case.
I'm assuming "hogged out" means the hub hole gets worn unevenly and enlarged. Not a term I've heard before.
Thanks for your input!
--
Bobby G.



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<stuff snipped>

Arf, arf!

I've gotten some pretty good leads on what I need. Today I found out the wheels are split-rims. That means I can transfer the tires from the new (possibly oversize) rims to the old ones without having to torture my arthritic hands dismounting a tire from the rim. I can remember doing that with full size tires before I saw how easy it was for a tire shop to do with their special machine with the rotating bar. I never did it by hand again after that!
If there's any lesson I learned from AHR and elsewhere it's that the right tool for the job is VERY important and many times it pays to rent something (like a ditch witch) rather than spend hours (days, weeks?) fussing with a post hole digger to run an underground wire.
My Harbor Freight multifunction tool was bought AFTER I stripped about 100 sq ft of glued down linoleum with a hand scraper. Boy was that a lesson in having the right tool. BTW, today I got a really nice Pittsburgh 25' tape measure free with coupon. Much better than the crappy flashlight or the Centek meters that read high, low and who knows?
So any potential solutions will wait until I can inspect the merchandise. The USPS says "shipping information has been received" - let's see a) when the seller actually gets it to the post office and b) when it gets here.
Ironically I was concerned about flats. The current tires have tubes and one has an as-yet unfound slow leak that started this process. I hadn't needed to use the scooter for a few months and when I rolled it out of the van, I heard the familiar thwup, thwup of a flat tire. I had to walk on my very bum knee to the X-ray center.
I decided then that I wanted to have a spare wheel with tire that I could carry on the scooter. Then I realized with foam filled tires (the new ones) I don't NEED a spare because they can't go flat. Ah, old age, where thinking things through becomes more and more challenging. So if the new rims don't fit, I'll take the old, worn tube tires off and put the new foam filled tires on the old rims and sell or junk the rims that are coming with the new tires. All predicated on the tires being dismountable. They could be glued onto the rims or not fit the old rims. It's always something.
Now the problem shifts to the nose wheel of the scooter which is a different size and is actually the most likely to get a flat because it's the leading wheel. I have been wondering if I can fill it with "fix a flat" goo and turn it into a foam-filled tire.
--
Bobby G.





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<stuff snipped>

gears.

position. Sometimes that is okay, but sometimes for timing or other purposes you need the gear at some other angle

and gear.

handled all the torque a gear needed.
You're another guy with a machine shop! (-: The ringfeder certainly is an interesting method of power transfer and I can see exactly why some applications might need it. I suspect in my case the key keeps the wheel from unscrewing itself - it's only held onto the axle with a single bolt and lock washer.
My wife has been saying "just call someone who does this sort of stuff" but I am still at the point where even if I did that, I would want to understand the dynamics of the problem. Eventually, old age will force me to delegate this sort of work, but not until they pry it from my gnarled arthritic hands! (-:
Thanks for your input!
--
Bobby G.




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On Friday, July 18, 2014 11:39:09 PM UTC-4, Robert Green wrote:

Actually I was thinking a ringfeder might be better for a less equipped person because it is self adjusting with only hand tools (hex wrenches) and has a fairly large adjustment range, and holds very securely. It's also easily removable.
What I hadn't thought about was that you'd probably have to bore out the hole in the wheel slightly, and yes that would need a lathe or broach and about five minutes work in a machine shop. Still, it might be worth paying to have that done for a set.
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On Fri, 18 Jul 2014 23:33:50 -0400, "Robert Green"

Those guys cheat.
In another thread, we talked a little about jackhammers. When I was in Managua, Nicaragua, in 1971, they were tearing up a sidewalk and using a a steel rod, maybe 1/2" diam. x 5'. That's all they were using. No jackhammer, no power at all. I was only inside for 15 minutes. I don't know how long it took them.

I love watching tracking on a package. It's like going to the horse races, but I always win.

I can see that time approaching. A friend who's only 55 bought a new house and I reminded her to get one-story. She'd already decided to.
How old are you?

I doubt that.

I don't think so. :-) There's a difference between goo and foam.
I've used fix-a-flat a lot**. Sometimes it only lasts long enough to get to the service station, which is still a good deal. But other times I drove on the tire for weeks or maybe months. I hear repairmen don't like it, because it makes fixing the tire on the inside a mess. I think the place where I buy tires has a sign warning people not to use it.
Until about 2 years ago, and for the previous 35 years, I carried 3 cans of the stuff. One can to use. One can so that when I had used the first can, I still had a can, and the third can so then when I used the first can I still had two cans and didn't have to go to the store right away. Why this sort of logic didn't cause me to carry 4 cans, I don't quite know. I'd have to think about to remember what I decided 30 years ago. But I hav so few flats here, I only carry one can now.
I also had a slow leak last year and I used a big can of Green Slime for that. It made it even slower. I've only needed air one time in 8 months.
I don't think goo or slime work with tube tires. I also don't think you can have a slow leak if the leak is in the tube (not counting the valve)
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On Fri, 18 Jul 2014 23:15:17 -0400, "Robert Green"

For most projects the Unimate is too small. I have a Myford Super 7 and it is more often than not too small. and too light for what I'd LIKE to do. Thankfully a good friend has a 10 inch heavy duty unit that is available for mr to use when necessary.

The average chair user is over 200 lbs. So is the average chair

You got it. If you are lucky it is only the wheel or hub that wears, and the axle lives to destroy another wheel. Quite often the keyway also wears. Then it's time to break out the torch and rebuild it with brass, and turn it down and re-broach it. Never as good as original, but usually good for another couple years if done right.

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