Bucket Un-Curls by Itself

[LD1]

I'm on the hunt for cylinders all the time for various projects. I've gotten many out of the salvage yard from scrapped equipment or just throw aways. The first thing I do is move the piston to center, fill both ends with oil then plug the ports. I use the shop press to do a push-pull test. (I have a pull-back ram also.) You can tell right away if a piston seal is bad. Just watch the pressure gauge so the press doesn't go over 2K psi.

You can accomplishing the same test with the cylinder mounted on the tractor with a load in/on the bucket.

IF the cylinder is 100% full, trying to compress it would do nothing at all. Only doing the extension test will tell you if the piston seals are bad.

 

[wdchyd]

Thanks for all the good info guys! I have the piston rebuild kits somewhere in the garage, if I can find them :duh: .

Look and see if the piston seals are just oring and backups, they can be upgraded to a better urethane seal

 

[wdchyd]

I was leaning towards the control valve because I would imagine that both pistons would have to be internally leaking in order to see unwanted curling...

If either cylinder is bypassing internally they will both not hold a load

 

[arlen4720]

It actually will work on the curl cylinders if drift is the problem.

If it has quick couplers, put the loader on the ground to take pressure off and unhook the curl cylinders. Raise the loader BUT NOT THE CURL. wait and watch for drift. Put the loader back on the ground to relieve pressure to hook hoses back up.

With a capped cylinder, you absolutly cannot compress the cylinder, regardless of the seals. Because the rod tries to displace fluid.

But it dont work that way trying to extend the cylinder. Extending the cylinder if the seals are bad can draw a vacuum. Vacuum acts more like air, IE: compressable or uncompressable. IF the seals are good, you are trying to compress the fluid in the rod side, and it wont compress so it wont move. IF the seals are shot, fluid can bypass to the base end. But since you are creating more space than the oil needs, you create a vacuum

I have found that even with healthy rod seals, that they cannot hold a vacuum and easily pull air in to fill the space from the extending rod. That is of course when you have bad piston seals.

 

[muddstopper]

Here is a pretty good utube vid I found that actually talks about trouble shooting valves and cyl. The part about capping cyl and testing seals starts at about the 35min mark, section 7, https://www.youtube.com/watch?v=WEHD-1Hac5E, but there is plenty of good info before that part that I found really helpful.