Hands are getting too shakey for doing this much anymore:

[Rob]

This is kind of what I'm up against with the cylinder lift. The lift cylinder resides in the center of the machine between the strengthening ribs. In front of the cylinder base is the rotary coupler which allows hydraulic fluid flow to the steering, drive wheels, and axle spreading cylinders. The cross tube you see in the photo(s) disallows the lift cylinder to be tilted very far so it must be pulled out almost completely vertical:

I'm thinking if I can attach a cinch strap around the mid upper portion of the lift cylinder body and pull it straight vertical, a helper can rotate the complete cylinder assembly towards the horizontal plane as the height increases clearing that horizontal tube. I could then back straight out with the skid steer. I did find a couple of square tubes in the shop I could use for weldments to secure the boom in an upright position. These would be cut off after the rebuilt cylinder is reinstalled.

Little hard to say for sure as I'm still in the thinking stage of the game.

[mrsmackpaul]

Do you need to remove the cylinder to change the seal ?

 

Paul 

[Rob]

1 hour ago, mrsmackpaul said:

Do you need to remove the cylinder to change the seal ?

 

Paul 

I am not 100% sure if I could leave the barrel in place or not. However I'm going to replace the hydraulic hoses at the same time and it looks much easier to do this if the cylinder is out of the way. The upper portion of the cylinder rod is a "T" and I've looked at it as a welded assembly. However viewing the diagram below, the cylinder rod could be threaded on the end with the cross tube forming the "T" and secured by a set screw, (#27) to prevent loosening. This setup is not apparently obvious from the vantage point I've had to this point. I will look later this morning when out to the shop.

[mrsmackpaul]

If you could unbolt the ram once the boom is propped and slide the base towards were you took those photos from and maybe work on it then 

This maybe a lot easier than yanking it out as getting it back in side the tight hole might be more of a challenge than the rest of the job 

If I was fairly sure I couldn't tackle this then inside the machine I would just yank it and deal with what ever head aches turn up

And yes I would also guess the T piece is welded to the rod

Perhaps find some bloles that fix these boom lifts and just have a yarn to them about how they tackle this ram, they may well give you some good pointers, the worst that will happen is they tell you to bugger off

 

Paul

[Rob]

Hi Paul and thanks. The bottom is just about two inches from the rotary coupler so no real room there to move around. However, the bottom mount is a trunion with a cap as shown here with #'s 19-20:

What I plan to do is to elevate the boom as much as possible, secure it in the upright position, remove the bottom trunion mount caps and loosen the upper pivot pin shown here in #'s 17-24:

Then retract the cylinder as in dropping the boom which will pull it up and out of it's cavity. I can then secure it to the lifting apparatus, remove the upper pin, and massage the cylinder clear. If measurements are correct, I shouldn't be too far off and it will come out fairly easy.

Thanks for your suggestion of contacting people whom do this work. I was able to speak with JLG technical support and to a gent whom actually worked on these when they were current. They did almost what I'm proposing but had a special clamping and rotating "jig" they used to lift the cylinders which clamped onto a forklift tine. I could make something similar and will look into this further.

Thanks,

Rob

Edited March 6, 2021 by Rob

[Rob]

Welded at the top:

Top seal pushed out:

 

[mrsmackpaul]

That top seal is only a dust whiper, probably just got dry and cracked

This then allowed the dirt to enter

 

Paul

[Rob]

Yes, I would think you are correct. It is a polyurethane material and exposure cracked in several places around the interior periphery. Given this only seems to leak profusely on the retraction stroke, (boom down) I would wager the sealing rings on the piston are still operating satisfactorily. It really sprays on the retraction stroke, yet is a restrained leak on the extension stroke.