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580C can't fit rebuilt ram into cylinder

L

LN Pipeline

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Joined
Feb 21, 2019
Messages
155
Location
Montana, USA
The lift rams on my JCB had a sharp 90 degree ledge where it transitioned from the bore to the threads. So sharp that if I slid my thumb along it with pressure, I probably could have drew blood.

I had to take emery cloth and smooth off the ledge before I could get the piston back in. I don’t know how the factory got them in without destroying the seals.
 
T

Tinkerer

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The shore of the illinois river USA
I looked at the cylinder in the parts book.
The cylinder is simply a plain ole Case cylinder. I am still wondering if the piston rings (seals) are stacked correctly and in the correct direction. It is crucial that the soft seal is in the proper location and not backwards on the piston.
There is no reference to a seal guide.
I need to reseal the boom cylinder on my own backhoe. If I have time tomorrow I will start on it and maybe see if it also has a ledge in the barrel. It won't be the first time for it either !
 
S

sled dog

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Apr 6, 2014
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342
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Hartdford City, In.
One time, years ago I had one that didn't want to go past the bevel. I wrapped the piston and seals with a sheet of VERY thin shim stock. The stock allowed the piston to slip past the bevel, then just gently pulled the stock out.
 
Swetz

Swetz

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Brass shim stock has worked for me in the past as well. I have also used the same shim stock around the seals with worm clamps (radiator style clamps). As soon as the seals are on, and still warm, I wrap them and tighten for about a half hour. Once removing the clamp, immediately install before the seals expand again. You may need a combination of the above.
 
geminijo

geminijo

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Jul 19, 2018
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46
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minnesota
Putting the rod/piston in the freezer overnight may also help.Just make sure you don't get any hydraulic oil on your frozen burger!:)
 
M

melben

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Williamsport, Pa
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Retired 50 Yrs with Case dealership
Just me but if that rough step is the issue, I would take a 1 inch ball on a die grinder and take that ledge out, the cylinder should have a taper to aid in starting the packing and it looks to me somehow it got roughed up. If you take my advice pack the cylinder with clean rags and after grinding make sure every bit of the grindings are out of the barrel and threads, one piece of grinding in the gland threads will ruin the barrel and gland. you will not be affecting where the packings seal in operation.
 
Coy Lancaster

Coy Lancaster

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I always take a screw clamp and put on piston seal to squeeze seal so it will install easier, when you install seal put clamp on it and tighten down until you get ready to put into tube then take clamp off and grease the heck out of it.
 
B

Bigdigger

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Joined
Nov 4, 2009
Messages
5
Location
Connecticut
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Test Operator
silverstr8p said:
Yeah, that's a lip, it's where the threads end and the beginning of the smooth section where the seals normally slide back and forth in the main part of the cylinder.

The ram slides in a bit, but then kind of binds on what looks to be about halfway through the first seal. It doesn't rip it or anything, just kind of jams, so that it seems if it was slightly compressed it would just slide right in.

I can't really see any pitting or rust of anything on that ledge, but it's just a tight fit. It's kind of hard to get a super straight shot since the cylinder is still in the end of the extendahoe box tubing, and I have a 3 foot piece of steel holding the end of the boom up off the ground so I could pull the ram out. That means the whole thing is kind of angling down.
Click to expand...
Use a ring compressor to squeeze the seals on the piston side then get some dry ice and immerse the piston and compressor in the ice for 30 minutes this will make the seals contract. Once you are ready to install take compressor off and use plenty of grease and it should slide in and then the seals will re-expand as they warm up. I do this alot in the aircraft industry in order to get seals to go into bores that are super tight tolerances. Its calles sizing the seals.
 
O

old and slow

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May 31, 2019
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Satellite beach
silverstr8p said:
I lost the seals in the 580C extendahoe ram, so took it all apart, pulled out ram from cylinder, put new seals on it, but now it won't slide it back in the cylinder. It came out hard too, unlike the bucket cylinder, which also was leaking so I rebuilt that too.

Here's a picture of the cylinder, all gooped up with grease to hopefully help. There looks to be sort of a "ledge" at the end of the threads that kind of catches on the endmost seal piece, is there something I can do to make it slide in without damaging the seal?

580C_extendahoe_cyl.jpg


I'm imagining some kind of tool/process like sticking a piston in a cylinder on a car where you have that clamp thing that holds the rings in tight?

Or maybe taking a little Dremel tool and sanding/grinding a radius on the ledge at the back end of the threads? What should I be doing here?
Click to expand...
Dremel tool it, also you are always better off honing a cylinder to break the glaze. Brush research flex hones work well 320 grit you can make extensions as needed, hone it and wash it good. The piston ring on my case 580d was a expandable type. I put them on then put the piston in the cooler for awhile. The material goes back from where you stretch it. The rod and piston require some force to get started. I also have ran into problems with replacement seals that where not exactly right. If your piston seal is a split pst seal put it on with whetherstrip adhesive hold it tight till it sets,a few minutes, then eat lunch and come back and assemble. The cranes i have done all have split piston seals and gluing them is the best bet.
 
silverstr8p

silverstr8p

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Oct 29, 2017
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Oregon
Thanks @moonlight , that piston compressor clamp thing worked! I put it on then waited a day for the seals to shrink down a bit, then put it in. I still had to whack it with a hammer to get it to slide in, but it clearly had less resistance than before. I pulled it out after inserting it a little bit to see if it was deforming the seals and it wasn't so I re-inserted and gave it some taps with a hammer, but it went in. Here's a picture of what I have.
580C_extendahoe_ram.jpg


It works and doesn't seem to leak. Now I'll put the bucket assembly on and see if it bleeds off over time, but it seems okay so far. Thanks for all the help!
 
O

old and slow

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Joined
May 31, 2019
Messages
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Satellite beach
silverstr8p said:
Thanks @moonlight , that piston compressor clamp thing worked! I put it on then waited a day for the seals to shrink down a bit, then put it in. I still had to whack it with a hammer to get it to slide in, but it clearly had less resistance than before. I pulled it out after inserting it a little bit to see if it was deforming the seals and it wasn't so I re-inserted and gave it some taps with a hammer, but it went in. Here's a picture of what I have.
580C_extendahoe_ram.jpg


It works and doesn't seem to leak. Now I'll put the bucket assembly on and see if it bleeds off over time, but it seems okay so far. Thanks for all the help!
Click to expand...
 
O

old and slow

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Glad you got it, on my 580D all the cylinders had a nice taper machined in them, one of the Grove cranes I have on the boom cylinder there is a machined out grove before the seal gets in the barrel, terrible design. I think it was for clearance for cutting the thread. We ended up filling it with wax, Gulf wax. We packed it in gave a surface for the seal to go over. ths cylinder was 8 inch diameter, so it was easy to work in the barrel
 
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