Hydraulic cylinder dissasembly

[dblazer]

I need to replace the seals in the lift cylinder for a JLG 40F and need help getting the cylinder open. The JLG parts page says it is made by United Hydraulics. It has a "thread ring" with 3 screws, (2) 1/4" x 1-1/2" cap screws and a small hex head 1/4" bolt. It looks like the cylinder end has an internal thread and that thread ring should just unscrew. I've put a lot of torque on it. First try was a tool made to bolt on using 1/4" bolts which sheared. Now I've tacked on a plate and 10' of pipe and can exert a lot of torque but it does not turn. So this is a pause to see if there's something I'm missing - otherwise the next step would be to apply some heat to the outside and get a longer pipe.
Thanks

 

[JeremiahSr]

Can you post a pic of the gland to see how it is set up?

 

[dblazer]

Hi JeremiahSr
Here's a picture of the cylinder though it's partly obscured by the tool I've welded on.
http://www.robax.com/pix/CIMG0745_1024.JPG
- thanks

 

[JeremiahSr]

The little holes there is for a special tool you can use a 3/4" drive ratchet on. That tooling will work just the same though. They can get tight! First check around the canister really good for any lock. If you see a small hole around it filled with dirt, dig it out. May have an allen wrench plug locking it. Some people install them with loctite. Looks like your doing every thing right. Puttin some heat on it won't hurt. I have had a couple that the threads galded so bad I had to have a new gland and canister made at a hydraulic shop. Not alot more you can do about it though. If it happens it happens. Good luck!

 

[JeremiahSr]

This is the tool. Can't remember where i got it. Was probally 15 years ago.

 

[dblazer]

Thank you JeremiahSr for the encouragement and especially for showing me the picture of the tool. I don't believe that tool would loosen this one though. Yes, I've searched the perimeter for set screws too.
If you have a moment would you explain how you attached that picture.
Thanks

 

[JeremiahSr]

sure. instead of quick reply hit Go Advanced. Then look for the little paper clip...says attatchments when mouse over it, right beside yellow smile face thing. then when that is open (seperate window) look for add files. then look for "Basic uploader" then you can browse your computer and attatch it. then hit upload. click done. should be there. you can preview your post before you reply. if it doesn't work..the file may be too big. have to edit it. crop then change pixel rating. most digital cameras have a high pixel rating making the file too big too be uploaded. test it here. see if it works.

 

[Lee-online]

Read this thread for some helpful info

https://www.heavyequipmentforums.com/showthread.php?11396-Hoist-piston-end-cap-removal-question

 

[willie59]

The gland retainer plate on those cylinders are bad about getting stuck. It's simply a round threaded plate that screws into the end of the barrel and pushes the gland in the cylinder. The cylinder is mounted near straight up on the 40F. Over time, rainwater seeps into the threads of the retainer plate and the threads get rusty and stuck. Peen the end of the cylinder like shown in the thread link that Lee-online posted, keep spraying penetrant lube on it, might take a while, but it should come loose. BTW, you did remove those 3 capscrews?

 

[dblazer]

Nice to hear from you Atco. Yes the cap screws are out and your advice is appreciated. It'll soak with penetrant tonight - will keep all posted.

 

[dblazer]

Thanks Jeremiah, Lee and Atco. The threaded retainer plate finally turned. It took a 12' 2" pipe with an 80 lb weight on the end (I was uncomfortable pulling on that pipe - it had a lot of spring) and heat from a torch around the outside of the cylinder end. (That was about 1000 ft.lbs. of torque)

 

[willie59]

Sounds like you had fun dblazer. Before you re-assemble all the components, check that the threaded retainer plate screws in and out of the end of the cylinder can easily. I'm very uneasy with the effects of heat on cylinder components.

 

[dblazer]

That's very good advice Atco, thanks.

 

[tonyw]

National Series 500B Boom Cylinder

I need some help. I have a1991 National Series 500B and the Boom cylinder is leaking oil. I need some directions on removing the cylinder, replacing the seals and putting the cylinder back on. Can anyone point me in the right direction.

 

[dblazer]

1991 National 500B boom cylinder

Hi tonyw

I'm not familiar with this machine but am willing to try to help. First step is to figure out how you will lift the cylinder out and what angle you need the boom. Then make a strong steel prop and put it in position. Then bring the boom down and press hard to make sure it will hold. Let me know if this sort of advice is useful.

dblazer

I need some help. I have a1991 National Series 500B and the Boom cylinder is leaking oil. I need some directions on removing the cylinder, replacing the seals and putting the cylinder back on. Can anyone point me in the right direction.

 

[tonyw]

@dblazer - I sent you a message