Question About Hydraulic Cylinder Inner Seal Installation

[Strangerover]

Hi. I was wondering what is the proper technique for installing the inner seals in the hydraulic swing cylinders (or any cylinders like this) for my Deere 46 backhoe. It's fitted on a 2520 and had been dripping a little fluid for some time. Well, the drip became a stream (under load) and I ordered the seal kit for this cylinder from my local Deere dealer, removed the cylinder from the machine, disassembled it and learned of the inner seal that sweeps against the chrome piston. I suppose this may be old hat to some of you, but this was my 1st hydraulic repair. I'm an auto mechanic, so I've seen plenty of wheel cylinders and master/slave cylinders and feel I have a decent grasp of the tractor hydraulics. I wasn't ready for the super-tight fitting seal in the bore, however. I got the old one out with my seal/o-ring removal tools (small, spoon-like picks designed not to cut or scratch), and I learned that it is a 2-piece seal. It's not that different than the cup/piston in an automotive wheel cylinder, I suppose. I lubed up the new seal pair and attempted several times to work it into the square-cut grove in which it lives, but the seals kept separating and twisting or not sitting in there right, etc. I finally got it in there using my pick spoons, but I certainly had to work and tuck the seals way more that I figured I should be. I had given the thing up for hopelessly kinked or cut/scratched, but it was sitting in there and felt ok when I ran my lubed-up finger around in there, so I assembled the cylinder. The square-cut rigid yellow seal in the kit was also a ***** to fit to the piston, and once on, it seemed stretched pretty badly. I put a hose clamp around it and gently tightened it down, then relaxed it and that seemed to improve the size of the seal. it was still stretched, but not as badly. The entire thing went back together with no leftover parts from the kit. I refitted it to the machine, fired it up and it seems to be working fine and dry, with only a little assembly lube on the piston on the 1st sweep. So far, so good, but should I be concerned about the beating the seals took going in, and is there a better way to fit these things on the future?

 

[Harry in Ky]

I"ve used the hose clamp trick for years on that type piston seal. After stretching the seal over the piston, I wrap the seal with a strip of emory paper with the back side against the seal. Then add the hose clamp and tighten as tight as I can get it. The paper is tough enough not to tear, and protects the seal from the hose clamp's notches. I do the piston seal first, so the clamp is in place while the rest of the job is in progress. Leave the clamp on as long as possible(I leave it overnight if I have the time) As for the shaft seals; Larger diameter shafts, 1 1/2" or larger, can usually be worked in with the fingertips, sometimes with the aid of a blunt screwdriver or some sort of tool. The smaller sizes can be a pain. I have a couple different sizes of a tool called a hydraulic rod seal installer. An internet search will bring up a dozen or so suppliers. The tool folds the seal into a smaller profile allowing it to fit through the bore in a sort of compressed state, then be released into the groove with little effort and no damage. They aren't cheap, but if one does a few cylinders in a year, the expense is well worth it. The tool can cost about the same as many seal kits, so one damaged shaft seal, the cost of a second kit and there you are.

 

[Strangerover]

Much appreciated!! I'll check out that tool, also.