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NC Wayne
12-15-2005 21:12:23
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Re: Trouble Rebuilding Hydraulic Cylinder in reply to Formerly PaMike, 12-15-2005 15:06:34
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Based on what your saying you've got the V (Chevron) packing in the head with the lips pointed in the proper direction (ie- the open part of the V points inward.) Like another post says there should also be a hard, formed bottom and a top piece that goes in the groove with the packing itself. Being Chevron packing the only thing that actually "loads" the seal is the pressure put on it by compressing it and putting in the snap ring. Typically these type seals are used in conjuction with a packing gland, that can be tightened periodically. This way as the seal starts to wear and weep the gland can be tighened to increase the load on the seals. I've never seen these type seals held in with a snap ring like your describing for this very reason. But you've got what you've got.... This being the case you can't simply leave a ring out in your application or It Will Leak because there will be no compression load on the seals. Now if the rod is tearing the packing going through there is most likely a square edge on the end where the piston bolts up. That edge isn't gonna go through the seals without causing problems. If that edge isn't tapered you need to take a grinder and put a slight taper on it. This ought to work and it isn't gonna hurt a thing when the cylinder is back together. If this doesn't work, and the the packing is wide enough to provide the needed clearances, the next thing to try is, of course, to leave them loose and not compress them til the rod is already in. In this case you can put the packing on the rod first, but in the future you can cut them at a diagonal to fit around the rod and replace them without totally diassembling the cylinder if need be. Basically all you need to do take a piece of pipe just a little larger in diameter than your rod but smaller than the OD of the retaining washer, and say 6 inches long, and cut it in half length wise to form a cuff. Slide all the packing down into the hole along with the washer. Now wrap the rod in masking tape, etc to protect the finish and put the length of pipe around the rod and clamp it looosly with hose clamps. Now, again providing the clearance is there, you now have way to push the packing down into the hole and still put the snap ring in place. If the eye end of the cylinder is shaped right you cshould be able let it hit the top of the pipe and use it to push the packing down in the gland and get the snap ring in the groove. If none of this wroks then the next thing I'd try, and personally I'd probably do this first anyway instead if using the Chevron packing, is to do what another of the posts suggests and find a "poly pak" urathane seal with the right ID, OD, and thickness to use in place of the Chevron. If there's enough room you may also be able to fit a piece piece of wear material in the gland to fill up any space the poly pak doesn't. Not knowing how much experience you've got with hydraulics I hope I've been clear enough in describing everything and haven't left anything important out, that I take knowing for granted, and made things more comfusing than the often are. If so please let me know and I'll do by best to clear things up. Good Luck. A good link to find just about any type of seal or wear band you might need is Hercules Hydraulics.
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