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Heather Mills - Amputee Forum
Ally

3R60 Tech question

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Hello everyone

I have 2 x 3R60 knees that are no longer working. I believe it is due to an hydraulic fluid leak.

It is not feasable to send these knees to OttoB in Germany to be repaired - they are not under warranty and the costs would be ludicrous.

Now, I have been looking at these units, and wondering "how hard can it be to fix?" No really..............!!!!!

Surely you just just unscrew them, take out the hydraulic fluid canister thingey, find the leak, see if you can repair/replace the seal (if that's what it has), refill the fluid and put it back together?

Or do you have to be a rocket scientist..........?

For obvious reasons, OttoB will not disclose to my CP what kind of fluid these knees use or any other kind of tech information on them.

Any ideas? It's surely worth a try, otherwise these units are useless to man or beast here in Africa.

I have an engineer friend who is willing to give it a bash. If we can get this right, and do repairs to our own old knees, wow - what a winning streak we'd be on here!

Your thoughts?

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Ally, hope your friend can help u out....reason for company not giving out that info to ur cp is MONEY `HONEY` MONEY. I would imagine he will be able to test fluid so he can help you. So glad ur back. :biggrin::rolleyes::laugh:

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Thanks :)

I want to know if anyone here on the forum knows what kind of fluid we need for these hydraulic knee units. And if I can give you the models, how much fluid we need to put in.....

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id say your best bet is to tear the hydraulic down and test the fluid. id say its a synthetic fluid

my old 3r60 is suffering the same issue and ive considered the same thing, ive even considered reverse engineering and making my own but ive never devoted the time and or research i know about pneumatic cylinder but hydraulic cylinder not as much.

i guess i could unpack my books re-install cad unpack my tools and hit the grind stone it be just like my old job

but you gotta be careful when dealing with patented parts

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I hear you Mr Gimp - but the way I'm thinking - we have absolutely nothing to lose mucking around with these "patented parts". They belong to me now. No warranty. And no assistance in the way of cost-effective repairs. I shall do what I like with them, me thinks. :tongue:

We're not changing them, or re-arranging them. Or trying to re-invent them (now there's a thought).

Testing the fluid could be quite expensive. Surely, come now SURELY there must be someone out there who will whisper in my ear what this fluid is, and how much each canister needs........I refuse to believe that this information holds international-security levels. Does it?

Sigh.......always such a darn fight.

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Patent laws only cover commercial interests so believe it or not its totally OK to manufacture your own parts even if they are patent protected but they MUST be for YOUR use.

Might be worth looking for a motorcycle suspension specialist, most knee units are very similar internally. If you find a friendly one then they MIGHT be willing to help you out.

Not sure which manufacturers have distributers near you but you want to look for names like Ohlins, Maxton, Showa they're all good manufacturers and a national distributer will have factory trained technicians who deal with high performance suspension systems all day long. They'll probably be able to tell you in seconds the type of fluid you need and will no doubt laugh when they see how little of it you need.

The only issue you might have is finding replacement seals as these could well be custom sizes.

Either way, good luck and keep us posted.

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Thanks Grum, I think I might try that. As for the amount of fluid - I suppose we have to hope that it must be full? (What the heck do I know about anything remotely hydraulic...) Because that would be a total guess if we don't get the specs from OttoB.

As for the seals - my CP also said that we may not find these, but he said "how hard could it be to try and make one of those little things?" Well, I'm holding onto that. How hard can it be? I suggested silicone, he said probably not a good idea. There I was thinking all those years that duct tape and silicone were the answer to all life's technical problems LOL!

Onward and forward.....any other people who may know, or could find out from OttoB....I'd be grateful if you could try and find out.

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Good luck to you, Ally...I hope you find some talented and cooperative hydraulic specialists along the way! :wink:

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Hi Ally, long tome no see but i am still around hehehehe..aboutt he knees you must first go to a store that sells hydrolic stuff and they should be able to help big time. They can no doubt tell what kind of fluid is it in to. Bring one of ur knees espically if one of them is leaking, they can look at the fluid and no doubt determine what kind it is. Dont forget to adk how much fluid is in any type od cylinder and ask if its proper to fill it completely. You might not have to do so..Heck they might even help you out in refilling it.

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Hi there, Stinker! Wow...it's "old faces" time here! I'm glad you turned up for this one...you're just about as determined as they come with keeping things going "on the cheap." If you, Grum, and Ally can't figure this question out together, then I assume that it just can't be done. Good luck and keep us all posted...even though I don't need an artificial knee, this is an interesting conversation!

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Diane!!! Blast from the past - trust you're good!

I got a very quick "hydraulics for dummies" lesson. Apprently in most hydraulic units, there are two compartments. One is empty, and the other is full. As you walk (or as any hydraulic unit walks, or pumps or whatever it does), the fluid will move from one compartment to the other as it goes along. Or something like that.....

So.....we are just going to fill up one compartment and see how it goes.

Another thing I learned from my "lesson" is that the seal could be a problem - they are precision made and we probably won't be able to make one up. We will have to try and find one somewhere that is the same. Unlikely, but worth a bash.

There I was thinking it was like a seal on a tap, a rubber thing. But no, not that simple, and certainly not those little rubber ring things LOL!

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can you post a pic of the seal if you have access to a shop you should be able to make one

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Hehehehe, we have to try and open the knee unit first - have asked someone with fancy schmancy tools to try - will keep you updated.

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I have the R360 knee and I've heard plunging noises from it lately. I think I'll be in the same boat as you. Mine is 5 years old this fall so I'll be able to get a new leg soon. I agree that the seals would be the hard part of a rebuild and the fluid not so much. I'd make a strong plea to Otto for some new seals.

I'm tempted to get another 360 on my new leg but I've got to watch costs and might go with a simpler knee. I am WAY AK and don't need or want to run. I think I've fallen more with the R360 than any of my old legs, since 1967. That stance flex whatever trips me up on occasion around the house. It's great when I'm motoring down the road with somewhere to go but short little steps forward and back etc screw me up 6 or 7 times a year. I'm an expert at falling but starting to get a little long in the tooth for hitting the floor.

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Hi there - I took a hellava tumble the other day on my 3R60 too. It was first thing in the morning, I guess I hadn't completely sunk into the socket, and yes, small steps around the dining room table - not good! I'm trying to be more "aware" first thing in the morning, and when ambling gently.

I wonder if there are any 3R60's around where something else broke, not the seal. Then we could take the thing apart and hijack a good seal.......

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I know someone who bought two knees (Totals I think) on E-Bay. She's thrilled with them - one for her, and one for her brother. I'm a bit wary of buying arty bits online though, probably because I'm always so far away from where they would come from.....

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Ally

I have had hydraulic mechanics take apart a hydraulic knee (Catech) before and they are very complicated. Both my mechanics could not figure out workings without blueprints (which of course are not availble). So I hope you can find someone that might be able to help, but wouldn't hold my breath.

Jeff

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