Repacking hydraulic cylinders

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SmokinM

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Got a few here on the farm that are starting to be more than an annoying drip or seep. How hard are they to repack and is it worth tackling myself or just head to the hydraulic shop. Any suggestions on where to buy seals etc. if I do tackle them. Any tips that make it easier? Thanks.
 
if they're on a branded piece of equipment the manufacturer should have the kits, otherwise you should be able to get most kits from a hydraulic supply.. Some are hard to do, others are pretty easy
 
Get estimates if you take them to a shop. On a MF loader I use to have one of the cylinders had to be turned and rechromed (had rust on it)then a kit put in, not cheap. Some you can get by with a new O ring.
 
If you do it yourself you always have the option of just replacing the seals in the cap where the rod goes through. I am a cheap arse and do that all the time if the piston seals look good. If paying someone to do it you just replace the lot.

Ken
 
I'm a heavy duty mechanic and I've done quite a few. Depending on the style of the head some require special tools to get apart but most don't. They're generally all the same inside. If they're small it's good to have the little tool that bends the seals that go inside the piston - big ones I just use a screwdriver to get them down there. Pay close attention when you take things apart and replicate but the main things to know are if a seal has a lip on one side that lip needs to point towards the direction you want to keep oil in. If an o-ring has a little flat ring (backing ring) in the same groove it needs to be on the outward side of where you want to keep the oil.

Cheapest way to get seals is to take them all out and to a hydraulic place to match up. Least pain in the butt (usually) way is to get OEM from the manufacturer.
 
If you do it yourself you always have the option of just replacing the seals in the cap where the rod goes through. I am a cheap arse and do that all the time if the piston seals look good. If paying someone to do it you just replace the lot.

Ken
That'll work at least 80% of the time. You can marginally up that by changing the internal lip ring in the piston. Sometimes the rod seal leaks because the oil is travelling between the inside of the piston and the rod. It's almost never the external piston seal. Ever taken apart a post pounder cylinder? The ones I've seen don't even have seals and the pistons are notched out.
 
I'm a heavy duty mechanic and I've done quite a few. Depending on the style of the head some require special tools to get apart but most don't. They're generally all the same inside. If they're small it's good to have the little tool that bends the seals that go inside the piston - big ones I just use a screwdriver to get them down there. Pay close attention when you take things apart and replicate but the main things to know are if a seal has a lip on one side that lip needs to point towards the direction you want to keep oil in. If an o-ring has a little flat ring (backing ring) in the same groove it needs to be on the outward side of where you want to keep the oil.

Cheapest way to get seals is to take them all out and to a hydraulic place to match up. Least pain in the butt (usually) way is to get OEM from the manufacturer.
You are way more skilled mechanically than I am. Thank you for explaining this.
 
I've got a Shaver pounder.... no piston seals, kind of a star piston, like a sprocket. They're built that way so that the cylinder rod can drop fast/freefall when you let off the pressure at the valve. Piston and rod just fall down THROUGH the oil in the cylinder then, instead of all of the oil having to be evacuated out of the cylinder. Not much oil actually moving through the cylinder then, just pressure, pressure relief. It's pure "pressure" in the entire cylinder length then that drives the rod back up, not a "sealed chamber" on the bottom side of the piston head. Don't need alot of volume of oil, but pressure is important.
 
I've got a Shaver pounder.... no piston seals, kind of a star piston, like a sprocket. They're built that way so that the cylinder rod can drop fast/freefall when you let off the pressure at the valve. Piston and rod just fall down THROUGH the oil in the cylinder then, instead of all of the oil having to be evacuated out of the cylinder. Not much oil actually moving through the cylinder then, just pressure, pressure relief. It's pure "pressure" in the entire cylinder length then that drives the rod back up, not a "sealed chamber" on the bottom side of the piston head. Don't need alot of volume of oil, but pressure is important.
Yes exactly. I was a little confused the first time I took one apart. The notched piston gave it away, helped me realize they were cheating to get the hammer to drop faster.
 
Done hundreds over the years. The hardest part is usually getting the head nut off, often the threaded ones are rusted and crusted in place.

Usually the easiest are the 2 snap ring style cap which requires nothing more then a couple of picks to remove.
 
Thanks for the feedback. I have 2 on a CAT 4in1 bucket I may try. I know they can get me all the right parts and fix anything I screw up.
 
You're welcome to pop them off and bring them to the house, I do all of my own. I'll show you everything I know, and after that 30 second class we can drink beer and goof off.

I agree with the folks above, best bet on kits is OEM. I've ordered kits from various aftermarket places (Baum comes to mind) and on occasion I've gotten seals that don't jive. Did the one on my round bale unroller last week (an antique 2.5"x1.125" Chief cylinder) and 75% of the seals were wrong type even though multiple online retailers spec'd that particular kit.
 
Got a few here on the farm that are starting to be more than an annoying drip or seep. How hard are they to repack and is it worth tackling myself or just head to the hydraulic shop. Any suggestions on where to buy seals etc. if I do tackle them. Any tips that make it easier? Thanks.
Labor charges can be extreme at a shop.
 
You're welcome to pop them off and bring them to the house, I do all of my own. I'll show you everything I know, and after that 30 second class we can drink beer and goof off.

I agree with the folks above, best bet on kits is OEM. I've ordered kits from various aftermarket places (Baum comes to mind) and on occasion I've gotten seals that don't jive. Did the one on my round bale unroller last week (an antique 2.5"x1.125" Chief cylinder) and 75% of the seals were wrong type even though multiple online retailers spec'd that particular kit.
Now that's a plan, I am really good at goofing off and a fair to middling beer drinker. I will pick some seal kits up at Carter this week and maybe if you got a day next week while the weather looks shaky we can get together. If not just let me know what works I am flexible. Jason is going to do the steer cylinders on my old tractor while he fixes some other stuff so if I can get these other 2 done that will be the worst of them. Thanks
 
Depending on the cylinder size, the kits may be close to the entire cylinder replacement cost when you can find them at discount online suppliers. Try Surplus Center for prices.
 
A few years ago I rebuilt 4 cylinders on my old round baler, never done one before. Pulled them apart and took pictures with cell phone. I always take pictures to make sure things go back together the way they came apart. Seal kits were about $30 for each. New cylinders would have been $200-300 each. My unskilled labor is free. All went back together with no major problems. Baler functioned much better afterward. As previously stated taking them apart is the biggest challenge, threaded the hardest, snap rings the easiest. Ones on the baler had the snap rings. Since then I have done a couple threaded ones which took lots of patience and brute force to get apart. Once that's done the hard part is over.
 
Since then I have done a couple threaded ones which took lots of patience and brute force to get apart. Once that's done the hard part is over.
I bought a huge Rigid chain wrench (36" or 48", maybe) just for that, add an 8' stick of pipe and sh*t gets real.
 
That or a big pipe wrench and a pipe. The one's w notches around the outside there's special wrenches and they lend themselves to being hit with a big hammer which loosens them fairly easy.
 

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