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Hydraulic piston repair- piston rings?

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  • Hydraulic piston repair- piston rings?

    Howdy Folks!

    Problem for today is the rebuilding of steering cylinder for my '57 Case 310 Backhoe/loader... I made a new piston rod for it over the weekend (to replace the badly scored and slightly bent original) and just welded the piston to the new rod (the original setup).

    Unfortunately while inserting the piston into the bore of the cylinder one of the two (presumably cast iron) piston rings snapped. The cylinder bore is 1.625", so I assume finding a replacement would be possible, but I have a suitable o-ring sitting right here.... Any particular reason I can't substitute an o-ring for it?

  • #2
    Oh, I should probably mention it's a welded cylinder, which means I'd really not want to have to cut it apart again if an oring won't hold up. Steering pump runs ~900 psi.

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    • #3
      A regular round crossection O-rings will work,but may also spiral and roll in the groove.You can get quad land O-rings from McMaster which are better.

      See Dual Seal O-rings

      http://www.mcmaster.com/#o-rings/=mc19t3

      Then there are also proper lip seals for hydraulic cylinders-

      See O-ring loaded lip seals

      http://www.mcmaster.com/#rotary-seals/=mc1cg6
      Last edited by wierdscience; 04-15-2013, 01:38 PM.
      I just need one more tool,just one!

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      • #4
        Thanks Weirdsience! Just got home (where my McMaster catalog is) and am now flipping through it. Grainger had a seal, but the 3 day delivery is no good. McMaster's 1/8" lip seals don't go up big enough, but will give them a call to see if they can get them. If not, I'll go with double seal o-rings.

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        • #5
          Here's another source: http://www.hastingsmfg.com/

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          • #6
            Originally posted by adatesman View Post
            Thanks Weirdsience! Just got home (where my McMaster catalog is) and am now flipping through it. Grainger had a seal, but the 3 day delivery is no good. McMaster's 1/8" lip seals don't go up big enough, but will give them a call to see if they can get them. If not, I'll go with double seal o-rings.
            Gee, I would think Philadelphia would have outfits stocking seals with expertise about what type seals would work as replacements. Have you tried an hydraulic repair shop for ideas, that would be my first stop?

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            • #7
              Originally posted by DR View Post
              Gee, I would think Philadelphia would have outfits stocking seals with expertise about what type seals would work as replacements. Have you tried an hydraulic repair shop for ideas, that would be my first stop?
              Exactly.
              Just did one last year on a case 580. Picked up a proper piston seal kit for under ten bucks at the Case dealership.
              Just had a quick look, there's five case dealers in your area. I'm sure there's at least that many hydraulic cylinder repair shops. Both of these would be an excellent source for parts and info, give 'em a call.
              Personally I would not use a standard "O" ring.
              Home, down in the valley behind the Red Angus
              Bad Decisions Make Good Stories

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              • #8
                I just went through this thought process a few months back when I had the digging power chain drive hydraulic pump apart on a ditch witch and the damn little pistons kept falling out onto the ground and I had to keep putting them back in,
                well - one of the rings broke in the process,,,, really bummed me out because im usually pretty good at stuff like this but this thing was very foreign to me and it was a heavy part that I was trying to get back on...

                anyways - there were about 8 pistons and the planetary looking swash plate had 9 lobes I think so the thing was always under power,,,
                the pistons were hardened steel and so were the bores and there wasn't anything for clearance - so with no real varying expansion ratio (like with an engine) I don't think a whole lot could get by the piston anyways and then a single ring with its exposed end-gap and all is going to stop the rest...

                so --- I thought about using an AC O-ring as there really good quality,

                then I was worried about it breaking down and potentially jamming the piston under pressure,,,

                so - long story short is I assembled the unit without the ring,
                it's been out digging since and so far so good - the only problem I could see in this particular set up is if the piston leak (along with all the others) exceeds the scavenger line that takes care of all the excess fluids that get by and the line can't handle it the system will build up too much internal pressure and blow a low pressure seal right next to the chain... we shall see I guess...

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                • #9
                  Strangely, none of the local hydraulic shops I've called stock cylinder components. They seem to only want to sell hoses, pumps, complete cylinders or fittings. And Case is no help, as they pretty much stopped supporting this backhoe decades ago (aside from the usual consumables, pretty much parts are NLA).

                  Going to make some more calls, but it's looking like the double seal o-rings I ordered are the only solution.

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                  • #10
                    Sorry for a bit of a bum steer, (no pun intended).
                    Hard to believe you could not get any help from your local shops, must be a local market attitude I guess.
                    I've always had very good service from the local shops in this regard. Most shops here have an excellent parts source network that they have cultivated into an almost no-fail system for NLA or NOS parts.

                    As a consolation prize I can give you a page that leads to not only a good source of hydraulic seals but is also quite educational in regards to differing seal types. Check out some of the other links that lead from there as well.
                    http://www.oringsusa.com/html/hydraulic_seals.html

                    Good luck.
                    Home, down in the valley behind the Red Angus
                    Bad Decisions Make Good Stories

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