So, 644e started a fast drip of oil out of the boom cyl on the right side, closer inspection shows its not coming around the shaft but what looks like the cylinder rod guide, so there looks like a few o-rings in there. R98669 backup ring and H88900 o-ring look like the culprit, being the only other seal that's not the outer rod seal. My question is, I'm familiar with small hydraulics up to the CK580, they have the piston held with a big honkin bolt with a large amount of foot poundage, all I can see on the JD parts explosion is a snap ring? Does a snap ring hold back a bazillion pounds of force when putting down pressure on the hydraulics? It might be nutless as its using a woodruff key from keeping any rotation to a minimum, not even sure how to pick the boom cylinder up to work on it!
I won't swear to this but I think the piston itself is threaded, you screw it up tight, back it off until the key fits in and locks it from turning and then the snap ring keeps the key from sliding out. It's a guess based on the parts picture and a failing memory of having heard it described some years ago.
I'd almost totally agree to that esp seeing a thread seal but would normally expect to see a square key versus a woodruff, I was expecting to have to go find a 2 inch air gun or a 50 foot long pipe extension but there's not much there in the pictures.
Yup, that does make one ponder... could be it is actually a square key, or I'm totally off base, lol.
Yeah, I guess either the internet will provide, Or, hell, I'll just tear it apart sunday, it sure looks like it weighs a lot.
If it was easy, anybody could do it, lol
Well, not that its hard, rebuilding a power shuttle on the CK580 wasn't hard but there were a lot of pieces Any opinions on OEM versus aftermarket seals? OEM is pretty pricey, north of $150 for the 'rod rebuild kit' I'll be saving the old parts to see what failed. Its probably one bad o-ring
I have not tried them, but several people on here have recommended https://www.herculesus.com/ and the web site looks good. After looking up your machine it seems their prices are no better than the dealer though. You might as well buy the piston seals as well, if the piston seals are bypassing the rod gland pressure goes up until the load stops or a port relief opens. Oddly enough in a twin cylinder setup it can be either piston that's leaking by, the pressure increases in both cylinders.
yeah, maybe just keep al the old ones and see about matching, there's a wear ring in the kit that looks pretty special. Wondering if a 3000 pound chain puller will be enough to coax the piston out.
Should be, of course you can always add a hundred pounds of shop air on the backside, though don't stand in front of it....
So indeed, its nutless! it has an o-ring and backup ring and the piston threads onto the rod, then where the picture shows a woodruff key, there's a 3/8x5/8x1 inch rectangle key held by a spiral snap ring, pretty basic, save that some of the piston rings are completely mangled!! more parts to order on Monday. Oh and someone put the main bolts in at about 1400 ft/lb where at best guess they should only be about 500 ft/lb will check the book later, gotta take it all apart again. Once I loosened up a few hose fittings, it didn't take much more than 100lb of force to move the piston in and out, came right out without much fuss.
That is when they made the cylinders so a tech could rebuild them on the bumper. They were simple then, and now days they torque the piston nut to the moon.
My Case backhoe boom cyl is something around 1000 ft/lb as most of the 580 ones, all the pistons are pretty high torque on that. The deere is much more agreeable on the huge stuff.
Trained Seals! I looked over the seals from herculesus and sure enough, they are about 10% savings from Deere, but wait, there's more, I bought a piston bore kit from ebay, reliableaftermarket and the bore kit was around $50, lo and behold what arrives is a kit from Bulldog, drop shipped from Hercules. Has made in usa stamped on it as well, maybe that's just the box. Aside from not being mangled, they look the same as what I have now.