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Shop made hydraulic seals?

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  • Shop made hydraulic seals?

    Hi all,
    I need some seals for an underbody hydraulic hoist. The hoist supplier says he has run out of stock and the replacements are on a ship in Italy, at least 3 months away!! Of course he would be happy to sell me a new multstage hoist to get me out of a spot. (would anybody buy equipment from a supplier who runs out of basic spare parts??)
    Question... is it possible to make the seals by turning them on a lathe out of solid rod. If so, what material. The old ones seem to be a moderately pliable plastic material. Any advice appreciated.
    The seals are 110mm diameter, 4mm by 7mm trapezoid section, with a groove cut into the pressurised edge.

  • #2
    Look in the phone book for local hydraulic parts houses bet they could match the seal or make one up. Have you tried caling the mfg. of the lift to see if they can ship you one or locate a dealer that has the part.

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    • #3
      One of the big questions is why did they fail. Chicago rawhide make all kinds of seals you may be able to find one that will work in your application.

      Dave

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      • #4
        try:

        http://www.metric-seals.com/?gclid=C...FQRM5QodiHZOow
        please visit my webpage:
        http://motorworks88.webs.com/

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        • #5
          These guys have nearly everything-

          http://www.zatkoff.com/
          I just need one more tool,just one!

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          • #6
            Thanks for those responses.
            The problem is that the manufacturer is located in Italy, the dealer in Australia (where I am) is out of spares, and the local seal manufacturers want an arm and a leg ($A60 each) to make one off replacements. That's why I am thinking about turning the seals myself.

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            • #7
              if theyre white then PTFE sheet is the usual suspect
              mark

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              • #8
                Directly answering your question
                Yes you can turn your own seals.
                There are many questions need answering as to design.
                The lip itself must be sharp, smooth, and continuous.
                NO knicks, No chatter, NO string burrs, No nuttin.
                Support suitable for pressure applied

                The seal material assuming some resilient plasticy stuff needs to be supported = jigs
                The cutting tool needs to be RAZOR sharp and lapped edge.
                Look at it under at least 10x magnification better 30 - 50x
                Tool rake adjusted for what you are cutting
                Negative rake pushes material away
                Too much positive will suck material in
                Just enough positive to balance cut pressure push to make material behave.

                I have done such myself with Nylon 11 and TFE
                Good results once you practice.

                Hth Ag

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                • #9
                  yea you can machine a polypack. Hell iv seen bulldozers with leather seals.

                  call your plasic man and see what he got. what choice do you have other than to make it.

                  If all else fail braze it all up with brass and its a piston once you machine it.

                  you can fix it.

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                  • #10
                    I guess the choice of material is going to determine how you machine it to a good extent. I've made seals from medium and high density poly sheet in 1/4 inch thickness, using a sharp cutter in a circle cutting tool. I adjusted the tool several times til the od and/or id became right with the first plunge of the cutter. No trimming to size in the lathe. This leaves the ring with a very smooth edge. Once the ring is cut out, I turned a piece of mdf on a faceplate so the rings could press onto that for cutting the groove. I plunged in a thread cutting tool, so the groove ended up with 60 degree sides.

                    For the rings I made, the id was where the lip seal had to be, so I positioned the cutter so it would cut that edge to a sharp lip. This actually expanded the thin edge of the lip inwards slightly, so it became a seal right away. The main body of the rings was cut to be a close fit, but not requiring expanding to fit onto the rod.

                    I suppose the first question should be what material is going to be compatable with the hydraulic fluid. Next might be what are the safety issues if this homemade seal fails. Then can you tolerate a short life span for the home brew seal, because chances are it won't last nearly as long as the right one.

                    It's unlikely that the material you use will scratch up the cylinder it's in, but you would want to consider that as well.
                    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                    • #11
                      Hydraulic seal

                      About 40 years or so I was a brand new Mechanical Engineer hired at the Saginaw Steering Gear GM division in the new product division. A dream job,
                      I was designing a hydraulic assist for power brakes using the power steering pump. I came up with and designed and had built a servo system with an O ring sealing the piston. It worked but the O ring suffered the stick-slip problem.
                      Teflon products were comming into use and I thought of putting a thin band of teflon under the O ring and it stoped the stick-slip problem and worked beautifully in test and in a GM car. Could not sell it to my boss but later 2 GM patent people were very interested.
                      Today this is called a slipper ring and just about every seal company has similar products.
                      Teflon is so ductile that kept in an enclosed place conforms to it. Even today I have machined teflon for seal purposes that works well.
                      So its an easy fix for situations like yours.
                      Walt
                      toolman

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                      • #12
                        Worth atry?

                        http://www.epm.com/

                        http://www.applerubber.com/

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                        • #13
                          This company is worth talking to.They machine from solid.
                          http://www.sealjet.com.au/

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                          • #14
                            If the seal groove has a rectangular / square cross section, you can make an energized teflon or ptfe type of seal using a standard o-ring for the crush. The teflon or ptfe works as the wear surface. Works GREAT! They sell em like this. Just have to do the calculations. Pretty basic.

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                            • #15
                              Originally posted by Mark McGrath
                              This company is worth talking to.They machine from solid.
                              http://www.sealjet.com.au/
                              That is a very helpful and interesting site, thanks Mark. .. John

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