Question on JCB swing cylinders

[BukitCase]

Oops, just re-read your last - you're right, leaving the cylinder BODIES in place and pulling the guts MIGHT be easier - it kinda depends on how hard those glands (end caps) are to get out. If THAT part is doable, I certainly would NOT take the entire assembly (cylinders, lower plate, etc) apart. Not only would it be a major PITA, putting it all BACK could be even more fun (got a couple EXTRA arms to hold everything lined up while you wrestle 300 pounds of parts back in line with 4 studs and 4 trunnion sockets??!?)

Good to know what your options are though, not to mention the fact that learning new stuff is almost always good... Steve

 

[Billrog]

Until getting the proper gland wrench I've taken them apart with a pipe wrench, or 2 punches in the holes and a bar to turn with very awkward but yours looks like it has a nut on it I've seen where shops have taken them off with a hammer and cold chisel but I wouldn't recommend it. One seal requires patience you have to turn it like a butter fly to get it on. As far as the backing seals for the O rings go I never replace them ( and have never had a leak) . Once the piston is off you can slip the rod out and replace the seal and wiper on the gland end. For reassembly you have to disconnect the hydraulic hose on the back end of the gland grease or oil everything up take your time and it will go back in without a lot of effort. Once together you hook it up and can use the hydraulics to center the I for getting the pin back in or just leave the hose of and use a lining bar . Best of luck and have fun.

 

[Richard]

The floor jack is mine. Don't have a transmission jack. Called the local hydro shop....she said if I pulled the guts and brought them in, they'd do it for me and hand the guts back.

Now, all I need to do is figure out how to get them out. I don't see myself paying $800 for that fancy wrench. I could probably call the dealer and have them come to my home, remove them.....and come back after they've been fixed to replace them for that much cash!

 

[Richard]

I like all the encouragement on having fun.

Why do I fear when the channel changes over to watching me actually in process of doing this, I'll be making every sailor around blush with my language?

Everyone agree that a huge pipe wrench might be my best bet? (that and perhaps a cheater bar slipped onto its end)

If it doesn't rain, I'll try to pressure wash the parts this weekend to at least get that part out of the way. (supposed to rain tonight and for a day or so)

 

[skyhook]

The two cylinders and bottom plate probably weigh around 80 to 90 pounds, I don't see a problem for the weight that your worried about.
Usually on JCB's, there is an allen key screw in there somewhere, so keep an eye out for this if you tackle it yourself.
If your that worried about the weight or braking a finger nail, call in a mechanic.

 

[crashz]

So you can't pull the plate separately? Floor jack will be fine with some guidance.

I'd pull the pins on the boom, disconnect the hydraulic hoses (label and diagram to make it easier) and drop the whole show. Then separate each cylinder from the plate and send them to a hydraulic shop to be rebuilt.

If removing the cylinders are a task for you (as the would be for any home mechanic) then rebuilding them will be much more difficult. We rebuilt the dump cylinders on our CAT IT12 and without some expert help, would have never got them right. Special wrenches, heating seals with boiling water, timing, placement and brute force were all needed. I supplied the brute force and willingness to learn.

 

[Richard]

I'll be doing this fix "in the field". Meaning, my driveway is gravel. I don't want the oil (which is sure to be spilled to some degree) in the driveway. Coming off the driveway is a dirt area (on a mild slope) where I park the machine.

I anticipate doing the work in this dirt area. Regardless of where I do anythying, I just see issues with whatever I do. It looks like if I remove the cylinders, they both come down at once. That strikes me as the easy part.

Getting them balanced and somewhat level so they can be lifted back up, while I'm using a 2 1/2 ton floor jack in the dirt, on a slope (in between tread marks in the dirt, making the dirt itself uneven).... I just see putting it back together as a real PITA. So, if I can simply pull the guts out, although that might also be a PITA, it might be less of one.

I'm thinking if I can pull the guts out, it will be an interesting experience. Perhaps one I later on, never want to repeat!!

Just yesterday, I bought a huge pipe wrench to see if it will work. If not, I've talked to a machine shop who will make a 3/4" thick wrench to fit the gland nuts for something like $175. I figure one of those two & a breaker bar should keep me in the fight towards success.

to clarify one of your second points... I don't personally plan to rebuild the ram (or whatever the guts are called)

Although I'm 100% confident in my abilities.... I'd rather just drop it off to someone who does that for a living and let them do it so I know it's done right from the git-go. (I'd prefer to take them the whole cylinder to be honest)

 

[BukitCase]

Some thoughts, mostly based on experience -

"a dirt area (on a mild slope)" - when you're dealing with heavy and/or awkward things on dirt, there's no such thing as a "mild" slope - BTDT - I would find/get a piece of scrap plywood at least 3/4" thick and a few 2x4's and make a LEVEL "runway" for your floor jack if at all possible.

"they both come down at once." - True - sometimes gravity CAN be useful :laughing:

" I just see putting it back together as a real PITA. " - Maybe, but if the trunnions/sockets on your cylinders are like mine, it might be easier than you think. It's possible that the sockets on that bottom plate are deep enough to keep both cyl's fairly well aligned while you jack the plate/cyl's back up into position, with just some minor guiding to line up bolt holes and upper trunnion sockets.

"I'd rather just drop it off to someone who does that for a living" - If you're going that route, I would DEFINITELY recommend dropping the whole shebang, taking the ENTIRE cylinders in, and having them REASSEMBLE for you. I can tell you firsthand, that even with the necessity of a come-along and a good external anchor point, those "guts" will come OUT much easier than they will go back IN - It's not a lot different than trying to install new pistons and rings in a newly bored out engine WITHOUT a real ring compresser and some experience...

Also - looking at your earlier pic, it appears that if the cyl's were resting on the plate with their LOWER trunnions sitting in the lower sockets, then the 4 studs that bottom plate attaches with, look to be long enough to start them into the holes in the plate BEFORE the upper trunnions would need to line up with their (upper) sockets -

If so, I would take the (rebuilt) cylinders (separately) and BALANCE them (by pushing the rod in a little bit at a time) til they will balance ON THEIR OWN on their lower trunnion - that way, you should be able to set them in their respective sockets (on the lower plate) - then, pick up that plate/cyl's and balance the ENTIRE thing on your floor jack (better if the jack can be raised just enough so it doesn't tilt the "load" by interfering with the jack's frame) - By balancing each cylinder FIRST, you will probably generate less "blue air" putting things back together since you'll have fewer things fighting you...

Next, (assuming you are working on your LEVEL scrap plywood) you should be able to roll the whole thing under the hoe and start lining up studs to holes - once it's raised just high enough to start into the stud holes, you can hopefully align the upper trunnions with their respective sockets - I've been known to hold two things in place while laying on my side and using my FEET to operate the floor jack, sounds like that might work for you unless you can conscript a HELPER

If you measure everything before you start, you may find that it's necessary to raise the hoe on the stabilizers and block it in place SOLIDLY - otherwise you may not have enough vertical room to manipulate the jack, plate, and cylinders without hitting the studs - (another comment from "blue air country" )

That's about all I have - hopefully a couple of these points will help the job go smoother for you - Oh, and you also might be able to get your money back on that pipe wrench :thumbsup: ...Steve

 

[Richard]

Finally able to speak with a JCB service guy today. He said they use a transmission type jack to raise/lower the cylinders. Said to be careful about the hoses...blah blah blah.... (get it)

He went on to say that the entire assembly would come down. I would not be able to loosen the bolts and slide the cylinders out of their mounts. Went on to say that in his opinion, the most simple way to do this without a proper shop setup would be to indeed, pull the guts out of the cylinders and leave the cylinders mounted.

He started giving me some tips on the actual rebuild.... I said no need. I didn't really want to do that part. I'll just get them to a shop. He gave a last tip about (what I think he called a key) under the first or second gasket on the piston. I think this key or pin is to keep the end nut locked (but am unsure until I see it)

I wouldn't have thought to look under a seal for something to release the end nut.

He said I might....or might not need a breaker bar on the wrench I have (24" pipe wrench). He felt the pipe wrench itself would be up to the job.

I went by a pawn shop yesterday looking. Found an old made in USA 24" for $20 out the door. Something handy to have around the house once in a blue moon so even if it doesn't work, I didn't really lose anything.

 

[BukitCase]

Can't tell a lot til I see it minus the crud, but it still looks to me like the lower plate comes off, probably with the cylinders but NOT including the upper trunnion sockets - so I'm not sure what he meant by the "whole thing" -

Problem with pulling the guts and just taking those in, is in putting them back. The piston with NEW seals is gonna be larger in diameter, the threads at the opening of the cylinder itself will have a tendency to either abrade the new seals or try to roll them out of the piston, and you're NOT gonna push the rod in by hand unless you're the Hulk's big brother -

I did that on my Case (rebuilt in place), ended up wrapping the newly ringed piston with .005" shim stock (wrapped slightly conical, with smaller end toward the hole) in order to get it past the threads - You definitely want the new piston/rings wetted with hydraulic oil - I then pulled the shim stock out as soon as all the rings were started into the actual bore - then with not too much effort (4 lb. dead blow hammer) I got the piston in far enough to START the threaded end cap (gland nut) - Screwing the gland nut back in will move the rod a bit further.

After doing this with BOTH cylinders I ran some tygon tubing down to the rear ports and refilled both back sides of the cyl's, then replaced all hyd. lines, tightened everything, started the engine and hit the swing pedals back and forth til most of the air was out (maybe 20-25 times)

All that with the rod pins NOT in place - you do NOT want to mess around with disposable body parts near hydraulics with air in the lines, they're too unpredictable since air compresses (so cylinders move unexpectedly) and (mostly) oil does NOT compress.

Once I had things bled, I stuck a large pin thru each cylinder rod in turn, and while SLOWLY actuating the cylinder I rotated the end til the pin in the hole was vertical, then moved the swing control til the pin holes lined up and replaced those pins and retaining rings.

I can't help you on the mysterious cap locking system, maybe if you could find an exploded view? Case (mine, anyway) just drills a small hole centered on the crack between gland and cylinder body, and drives a 6-32 screw in there.

Note - it actually sounds to me like the JCB guy was talking about the piston end of the rod - maybe a square key in a broached slot in piston and rod. I would think that would prevent the 400+ foot pound piston nut from wanting to loosen as easily.

If you can, post pix after it's clean, might shed some light on something new... Steve