Help? -- to reassemble hydraulic cylinder

   / Help? -- to reassemble hydraulic cylinder #1  

Sodo

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Cascade Mtns of WA state
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Kubota B-series & Mini Excavator
Trying to reassemble a 'repaired' leaking cylinder. Proper repair of the cylinder (ram rechrome + $100 seal kit from mfr, +labor) was estimated to be $1,000+, and a new cylinder assy is $974. I was inclined to try to fix it, as the pitted part of the cylinder can be avoided most of the time if I'm careful using it. The bore is 2 1/2".

I removed the rod, put it on a "roller bearing contraption", and polished it with an air grinder and polishing pads from Harbor Freight. The HF grinder finished the job. The pits are still there, but much 'softer', it's a vast improvement over the 1st pic below.

I bought new packing $13.49, and now with $35 of HF tools I'm into it for $50 plus my time. Putting it back together now and I'm wondering if I need a special tool to insert the ram packing? The cylinder is nicely chamfered, but the packing seal is pretty stiff, the same size as the chamfer, and won't go in. Is there a "technique"? Or do I need a special tool? :confused::confused: Thx for tips!!

crown_pitted.JPGcrown_chamfer.JPGcrown_ram_packing.JPG
 
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   / Help? -- to reassemble hydraulic cylinder #2  
Lubricate them with grease or hydrualic fluid?

Aaron Z
 
   / Help? -- to reassemble hydraulic cylinder #3  
Not sure from the pix, but if the bore is in the right range, you could use a piston ring compressor as used in engine rebuilding - if not, maybe a large stainless hose clamp carefully tightened around the packing, leaving just enough packing protruding toward the open mouth of the cylinder to get it started - once it's started, move the hose clamp a bit further away from the mouth of the cylinder and push some more. (AS mentioned, a bit of hydraulic oil probably won't hurt)

Barrel mounted in a large vise, maybe a comealong thru the pin end of the rod and back to the far end of the barrel for a bit more "persuasion" - The whole thing looks a bit large for a hammer to work, that's why I brought up the comealong idea.

Best of luck... Steve
 
   / Help? -- to reassemble hydraulic cylinder #4  
Line it up as straight as possible and use a feeler gauge blade or rounded awl to get the ring started in the bore. Careful to not rip the edge. Once it is started and in the bore a ways you can just slam it home.
 
   / Help? -- to reassemble hydraulic cylinder #5  
Take a 2 litre pop bottle, cut it open, make it into a circle, lube with oil. Wrap it around the seal and stick it slightly in cylinder and push it in.
 
   / Help? -- to reassemble hydraulic cylinder #6  
Take a 2 litre pop bottle, cut it open, make it into a circle, lube with oil. Wrap it around the seal and stick it slightly in cylinder and push it in.

That works good, or I have used thin brass sheet stock also.
 
   / Help? -- to reassemble hydraulic cylinder
  • Thread Starter
#7  
Thanx very much for the ideas. I would have used a thin sheet or a ring compressor if I had one, dangit.:rolleyes: I've used hose clamps for piston rings, but it seems the screw-drive 'chunk' would get in the way. GREAT idea on the pop bottle, that seems feasible (and plentiful too). I'll measure the diameters and see what clearance is available. I think sheet might be "thinner" just need to find where to get some.

Yes, go round and round with a round awl, that seems feasible too but the seal has to go past two chamfers, at the top, and a second slot about 1/8" further in (for the gland retaining ring).

It just occurred to me to try a hoseclamp to compress the seal real tight, then take it off quickly, and quickly shove it in the hole before it rebounds?

Anyway, tomorrow I'm gonna try some of these ideas, thanx a million!

How does a hydraulics shop do it?
 
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   / Help? -- to reassemble hydraulic cylinder
  • Thread Starter
#8  
Here's some more pics, before and after, the polishing tool and the 'spinner' for the ram. I was happy that the ram was not bent in the slightest.
At this point still have not reassembled the cylinder but will try next week using some of the suggestions given.
 

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   / Help? -- to reassemble hydraulic cylinder #9  
   / Help? -- to reassemble hydraulic cylinder
  • Thread Starter
#10  
Good suggestion thanks! I've seen those little rolls of aluminum at Home Depot. I'd be suprised if it was quite a bit thinner but will definitely check the thickness if the pop bottle doesn't work. A beercan comes to mind as well, it might be about 2.5" Or a steel can might work too.

The cylinder has a one-inch 'plug' at both ends (no clevis) as in the pic. A gravity force at each end holds the 'plug' in its hole. I don't know why the cylinder is double acting, it only 'pushes'. and it cannot 'pull' or the plugs would just come out of their hole. Might be something to do with safety, or overhead use, maybe it needs measure the fluid speed both ways.

I could probably cut the ends off the 36" from surpluscenter and weld pegs on. That looks easy - thanks very much for the link. If my 'fix' doesn't last long enough to satisfy I will get that one you suggested. Haven't measured the stroke but the cylinder is 42" long so 36 is a good guess.
 

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