Relieving pressure on hydraulic cylinder

[BeezFun]

A single acting cylinder on my lift is squirting oil out the vent, so I assume the cylinder seal is bad. The check valve has 4 lines coming into it, I assume because it's synchronized with the leveling cylinder on the basket. My question is what is the safe way to relieve the pressure on the cylinder so I can remove it?
Here's a stick figure of the lift, I need to rebuild cylinder B:


The lift is in the rest position, so I can't see there being any mechanical forces on the cylinder shown by red arrow:



Here's the whole lift:

 

[oldnslo]

With lift fully lowered is that bucket arm sitting on a mechanical stop? Looks like it is in picture but not sure. If on mechanical stop there should just be little to no pressure in that line to the cylinder.

 

[BeezFun]

Yes, the bottom of the cage rests on a rubber pad, and the frame at the opposite end also rests in a cradle pointed to in photo below. I would feel better if that cylinder flopped around a little when I try to move it. It feels like it's being held very tight and I won't know for sure until I drive one of those pins out. Is there any reason to take that check valve off the cylinder when I rebuild it?

 

[oldnslo]

Is there some way that you can slightly lift that boom segment with an overhead chain hoist or a jack underneath to relieve the tension on the cylinder pins. Not sure how close to end of stroke that cylinder is when sitting on stop.

You should not have to remove the check assembly to rebuild the cylinder.

 

[BeezFun]

Is there some way that you can slightly lift that boom segment with an overhead chain hoist or a jack underneath to relieve the tension on the cylinder pins. Not sure how close to end of stroke that cylinder is when sitting on stop.

You should not have to remove the check assembly to rebuild the cylinder.

Yes, that's a good idea. Surprisingly I did find a brief description in the manual about removing the two main cylinders. It says the one I'm working on can be removed without any additional support. The other cylinder requires a forklift or something to support the upper boom while the cylinder is removed. I know what I'm doing tomorrow...
tnx

 

[BeezFun]

You should not have to remove the check assembly to rebuild the cylinder.

In your experience is it better to remove the 4 hose fittings from the check valve, or remove the check valve and leave hoses attached? I'm thinking it terms of the likelihood of having leaks or issues putting it back together.

 

[oldnslo]

Do you have some way of covering or protecting the check block mounting surface? If yes that could be an easier solution since less risk of connecting hoses wrong or a fitting leaking. There will be a seal between the valve body and cylinder. I would expect a simple o-ring but not 100% certain. I can’t tell on picture how that block is mounted.

Protect the mounting face on the cylinder also since a nick on that surface could cause a leak also.

 

[BeezFun]

Do you have some way of covering or protecting the check block mounting surface? If yes that could be an easier solution since less risk of connecting hoses wrong or a fitting leaking. There will be a seal between the valve body and cylinder. I would expect a simple o-ring but not 100% certain. I can’t tell on picture how that block is mounted.

Protect the mounting face on the cylinder also since a nick on that surface could cause a leak also.

I don't have any way to protect the surface, other than some painters tape. The seal between the valve body and cylinder is shown in the parts manual as a "dowty washer" which is some British thing, and a Banjo bolt with what looks like two crush washers. I'm thinking I'll take the hose fittings off and not mess with the check valve.
tnx

 

[BeezFun]

Got it all apart, what is the purpose of the diagonally machined slot in the retaining nut on this rod? All it looks like it does is make the nut weaker.



Seals were cracked from age but the cylinder and rod look like brand new. This cylinder was taken apart before I owned it, so the seals are at least 10 years old. I was pleasantly surprised that the OEM seal kit was $35 and they had it in stock. That saves me taking it to the local hydraulic shop to get after market seals.

 

[oldnslo]

No clue on that slot in the nut unless it was meant to bent in to act like lock nut once assembled but that is 100% pure guess.