Broken Wheelchair part, need help

[aaxiss]

Looking for someone in SoCal that may be able to help me with as I don't have the knowledge nor the tools. Today I sheared the key on my axle and it really did a number on the key way as well as the axle. The key way on the axle now has tapered sides and the new key wobbles in the slot not to mention the bit in there acted as an abrasive and galled up the axle pretty bad.

The axle used to be a machine fit and now wobbles and the loose key way allows the wheel to rotate on the axle about 10 deg or so. I am disabled ( Paraplegic ) with some LeftBrachial plexus nerve damage to my left shoulder which make a manual ( push ) chair only viable for in the house. The inside bore of the wheel was damaged also but dosen't seem too bad, the key way is ok as far as I can tell.

I really depend on my power wheelchair like you guys depend on your legs, and Sunrise Medical only sell motor and gearbox combos $ 1250

Here is what I am talking about, you can see how the new key stock has gaps on ths sides which is allowing it to roll side to side. Any thoughts ( on the cheap ) would be appreciated. The Wheelchair is a quickie 626 btw. If you happen to know of anyone who might have a donor

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[ScratchStart]

how hard is it to remove that shaft? it could probably be built back up and machined back down... if it comes out...
i'd be leary of welding it up with it in the motor, could damage seals and stuff.

good luck man

[dirtyfarmer]

Another option would be to look into some kind of Loctite product or other dedicated epoxy/metal-filled (Metalset?) product designed to make permanent repairs on worn shafts/hubs. I know there are products out there to do exactly what you need. You'll have to do some research.

[sportbike]

Can you post up the mating part? Is it the actual wheel? Also, do you have calipers or an other way to measure the diameter of the shaft? Also a measurement of the length of the shaft (just the full diameter portion, not the reduced threaded end) woudl be beneficial.

John

[sportbike]

Looks like folks use the parts for battle bots and some are avaialble on Ebay:

http://cgi.ebay.com/QUICKIE-MOTORS-P...32637481416200

http://cgi.ebay.com/QUICKIE-MOTORS-P...33307495721081

http://cgi.ebay.com/Quickie-Rythm-Po...34249732430859

[sportbike]

This appears to be the manufacturer of the gearbox for the drive. Looks liek they may be able to sell just the spindle as well:

http://www.fracmo.com/english/sparesform.htm

[performance]

Of course, this is a welding site, and the welding option would be first, though it may not be practicaly for you. If you can pull the shaft and weld it up, a new key way can be cut. But, a more practical solution is to use a high strength epoxy, like JB weld to fill in the shoulders. I know it sounds amateurish, but there are legitimate applications for JB, and in situations like this, properly done, it will last a long time. A small dremel can be used deftly to smooth it out to fit into the female housing. I don't think you will have a great problem when it is finished, since the very bottom of the groove will keep it mostly secure. I believe it would be a sound solution. Most likely, even though the sides are wobbled out, the new key won't move much. I'd be more concerned about figuring out why it sheared, unless it was being used for drag racing.
If you can figure out why it wobbled back and forth (probably from a partially sheared key) and fix that cause, it may not give any more problems.

[worntorn]

Why not get some larger key stock and make a key to fit tight in the slot? The keyway looks as though it has plenty of shape left to do the job.

Key stock is easy to shape with a grinder and then file for finish. Of course the part of the key that sticks up above the axle would be filed to fit tight in the wheel keyway, so there might be a little notch one side or other (or half on each side) on that part of the key, depending on how much wear is in that part. You could leave enough height on the key that the wheel is a drive(tap) fit onto the axle, this would tighten things up nicely.


If you were close to my location I'd be glad to help with it.

[Rivets]

Hey Aaxiss,

+ 1 on what Worntorn said. I would add that you could remachine the keyway to square the bottom with the shoulders.
Then a new key as mentioned. I had this done before, and the machinist called it a "step key".

Cheers,
rivets

[jakeru]

Wish I could help you but I'm not local.

In addition to what has been said previously, having the key brazed into the keyway is yet one more option to take some "slop" out of the key. It is possible the keyway in the wheel bore has similar wear and may need attention as well.

Whatever key slot restoration idea you go with, when it comes times to reassemble, make sure you torque the nut that retains the wheel to the axle to its *full* torque specs. It is likely IMO, that an undertorqued wheel nut caused this key wear. Also, make sure to first clean away any oils/lubricants away from the axle to wheel mating surfaces prior to reassembly; they should be completely dry and unlubricated. Even roughening up the faces of the mating surfaces with some sandpaper (the surface ones that "clamp" against each other when the nut is tightened) wouldn't be a bad idea to increase wheel holding friction. I also like the idea of a little low-strength threadlocker (like loctite 242) to add a little extra friction, and help prevent water from ever getting in there, which might act as an unwanted lubricant.

In summary, the nut and the mating surfaces that clamp the wheel to the shaft will ideally be able to provide enough friction so that the wheel will not slip on the shaft, IE: even if the woodruff key were completely left out during assembly, the wheel would not slip. If they are doing their job right, the woodruff key is just an insurance policy, to prevent a complete loss of control if slippage does occur.

[aaxiss]

thanks all for your suggestions and offers, here's what I have decided to do. With motors and gearboxes being so plentiful on Ebay I have decided for now to go the JB Weld route and hope that holds untill I can buy a set of used motors and gearboxes. then I will remake the motor/gearbox carrier on my wheelchair to accept the new motors and gearboxes.

I purchased some new spacers that are about .050 thinner so that will allow enough of the shaft to come through the wheel so another spacer can capture the shaft and help center the wheel. the spacer I have for the top is thick enough to allow the shaft about 3/4 the way into it without allowing the nut to bottom out on the threads.

BTW the keyway is kinda rounded over in the wheel also but there is not much I can do about that, machinists want good money for their time so I wont even think about that route,

Heres the pictures

Attachment 1382Attachment 1384Attachment 1385Attachment 1383

[sportbike]

I am not sure what you are showing in the last two pictures?

If you don't need to remove the wheel often, you could put some JB weld on the shaft and keyway and then install the wheel. The JB weld should fill the gaps to take out the slop/wear from the wheel moving. After putting the JB weld on, install and torque the wheel and leave it sit for at least 24 hrs. If you will need to remove it later, you can rud some candle wax on the stub shaft, then sort of polish it in with your fingers to get only a thin coat. Then put the JB weld in the hub and install. The JB weld will stick "less" on the waxed portion, often allowing the part to be removed.

I once put JB weld on each side of a v6 Buick engine block that had split badly from freezing. I normally would not recommend doing that, but they didn't have alot of money and had no other real choice. I bought two of the small packs and used one full pack on each side, added some masking tape, and let it sit for almost 2 days. Removed the tape and filled the cooling system with water and left the cap off. Started the engine and let it idle for about 45 minutes to make sure the JB weld was cured. Once I ran it with the cap on and saw that it was sealed, I drained some and added antifreeze.
I spent about $20 total on the repair. I didn't charge them a dime and they drove the car for 2 years afterwards, never having an issue at all!

John

[aaxiss]

last 2 pictures are the mount showing where the motor and gearbox go. the last picture towards the top of the bracket yo will see a radius the motor clears that by only about 1/16" which right now limits me to a direct replacement. I will be making another bracket like that one in the future to accept any motors I buy to replace the damaged one I have now.

[Robert s]

I realize that I am not in your area, but if your repair does not go as planned….. I would be willing to do the repair and machining free of charge. This offer also goes too any used unit you may order on e-bay that may need some repair.

I think that the repair plan that you have will work, but if not just let me know if you need any help.

[Oleg]

I realize that I am not in your area, but if your repair does not go as planned….. I would be willing to do the repair and machining free of charge. This offer also goes too any used unit you may order on e-bay that may need some repair.

I think that the repair plan that you have will work, but if not just let me know if you need any help.

Robert , if you can do the labor. Everlast will cover the shipping both ways.

I don't mind helping Don

[worntorn]

that sounds like a plan.

If for some reason it doesn't work out, please ship the unit to me in Lynden Wa.
I can fix it either with an oversize key or by milling new slots.

If Don is put in the crate with the chair he can get a trip out of it and give my Egli build a close up inspection!

[Robert s]

Robert , if you can do the labor. Everlast will cover the shipping both ways.

I don't mind helping Don

That is a deal just let me know and I will get you the info.

[aaxiss]

Robert If this doesn't work I will pull the gearbox apart and contact you on the forum. But what I am trying to do is get myself mobile in the shortest amount of time. Problem with your fix is that it takes care of the axles but not the keyway inside the bore of the wheel, but a set of wheels on ebay definitely doable for $100 or less. Also extending the keyway longer toward the gearbox would help too, that would add another 6mm as the slot in the wheel is full length.

Oleg I appreciate the offer of shipping also but 2 axles should cost no more than a few dollars each way Hopefully this holds Till I can buy some motors/gearboxes off ebay and then build a new swing arm and gearbox mount. Swing arm?, yes my wheelchair has suspension .... 2" rear travel or 1/2" with me in it LOL

here is what the key way in the wheel looks like BTW

Thanks again Guys

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[Robert s]

Robert If this doesn't work I will pull the gearbox apart and contact you on the forum. But what I am trying to do is get myself mobile in the shortest amount of time. Problem with your fix is that it takes care of the axles but not the keyway inside the bore of the wheel, but a set of wheels on ebay definitely doable for $100 or less. Also extending the keyway longer toward the gearbox would help too, that would add another 6mm as the slot in the wheel is full length.

Oleg I appreciate the offer of shipping also but 2 axles should cost no more than a few dollars each way Hopefully this holds Till I can buy some motors/gearboxes off ebay and then build a new swing arm and gearbox mount. Swing arm?, yes my wheelchair has suspension .... 2" rear travel or 1/2" with me in it LOL

here is what the key way in the wheel looks like BTW

Thanks again Guys

Attachment 1386Attachment 1387

I understand you need it quick but let me know if you need help. I always have time for projects like this. Just let me know.

[aaxiss]

First of all I wish to extend a heartfelt thank you to all who responded and offered their advise or help ..... Means a lot to me. My wheelchair is once again back up and running like a champ again. The JB weld seems to be working but one thing I noticed is that the key stock I had in there wasn't going but half way up into the key way on the wheel so I cut down an old band saw blade and wet sanded it till it was a light pressure fit into the gap between the top of the key and the wheel key way. put the axle washer on and a bid of blue locktite on the threads and torqued it to specs and Just got back from a 7 mile round trip with no hint of anything amiss.

First picture shows shim I put in key way, Other just show my reassembled chair and the suspension that someone asked about

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you guys rock, thanks again

Don