Replacing hydraulic oil seal

My old JCB digger is leaking too much oil from one or two rams so Im going to have to replace the seals. As this isnt something Ive done before I thought you guys could give me a few pointers. The first one Im planning to do is shown on the second picture. Am I best doing in on the machine or removing it and taking into the shop to work on. I know its not exactly the same set up as the machines you folks have but Im guessing the same general approach would be the same.
Thanks
Bill
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A guess would be to loosen the end cap where the ram comes out, while it is on the hoe. It looks to me like a pim hook spanner is to be used in the visible hole to unscrew it. (a Guess). It is far more stable where it is for getting a grip on the cap. Jim
 
Loosen gland nut while on machine. Disconnect hoses pull pins. Get in big vise pull rod/gland out. Take big nut off that holds piston on slide gland of to replace seals. Side shift hoes arnt real plentyfull in USA
 
Loosening the gland can be the hardest part sometimes as they rust in hard depending on design and material. Never seize it when reassembling. I often take them off and clamp to a stout bench or forklift then push the wrench with my backhoe or other machine. Heat may be needed as well
 
One like that is best left on the machine. As another post said, use a pin spanner, if available, to take the gland nut off. If no spanner available, use a big pipe wrench. Give it some love taps with a hammer before trying to break it loose, and as it comes off. The love taps will usually help it break free if it's rusted, which I'm sure it is.

Once you have it loose, loosen the hoses so the air and oil in the cylinder has somewhere to go as you pull the rod from the barrel, and as you put it back in.

With a cylinder as accessible as that one, I usually leave the barrel attached, and just remove the rod. Once the rod is out, either hold the end of the rod with the hole in a vice, or put the hole around a rod to keep it from turning as you take the nut off the other end. Check the nut for any kind of lock as there is often a set screw, etc used as a keeper.

Once the nut is off remove the piston from the rod, and then slip the gland off the end also.

With it off you should be able to see the rod seal/s, a rod bushing if used, and then the part you can see from the outside, which is the wiper.

Take the seals, O-rings, etc all out of the gland, remove the seals from the piston, and get them matched up.

Once you have the new parts, put them all back in their respective spots. Just make sure the rod seal is installed the right way or it won't seal. Some piston seals will work either way, some only one way, so insure it's right also.

Once all the seals are in, simply reverse the disassembly process to put it all back together.

This is somewhat generic in nature as there are many different cylinder designs. If you run into any issues, holler back. Good luck.
 
good luck,like they say, them things can get growed on. had one on a 416 cat that a 6 foot pipe wrench and cheater wouldn't budge. ended up taking it to cat. dealer to have repaired...
 
Bill,
I'm always working on my hydraulic cylinders. I find mine leak because of nicks on the chrome rod or cracked welds. I came up with a way to polish the nicks out using a 1 inch sanding belt, 120g and turning it inside out. Made up a device to use on drill to power belt. Then I made a belt using emery cloth and stapled the ends together. Puts a mirror like finish on the chrome. Short off spending a lot of money to have rod re-chromed, this works for me. I can't tell you how many cylinders I've worked on, have two backhoes. Checks for any scratches or nicks on rod. geo.
Link to previous post
 
FIRST, before applying a Spanner or Pipe-wrench to the Gland Cap, check the Gland Cap carefully for any SET-SCREWS ( there may be more than one ) . It's a real pain in the arse to find after you've removed the Gland Cap, that you've buggered the cylinder threads because you missed finding a set-screw. BTDT!


Doc
 
Bill,
I leave my cylinder on tractor, remove the end cap. Then I run motor at an idle and use hyd pressure to remove the piston and rod. Sometimes mine gets hung up inside cylinder. Be careful, point the cylinder away from everything. One time my rod went flying 20 ft before it landed and missed my truck by inches. Then I use a brake hone on a drill to clean the rust off the inside of the cylinder where the O-ring on end cap goes. Not sure if yours is like mine. Biggest trick is removing the end cap. Then my local hydraulic shop sells me the parts I need to repair the end. Mine are so easy to take apart, I only put piston parts on if needed. I also cover the cylinder pointing up with rags, sometimes plastic to keep rain water out. I find rain water and the fine dirt eat the O-ring causes it to leak. I store mine under roof when not in use. geo.
 

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