FELL Bucket curls back very slow

[lzicc]

I posted a thread about this in another part of the forums. My dealer will be picking up the Kubota at the end of the month, but I want to try one more time to fix it myself. Here is a quick rundown of the issue.

I had my forks on the tractor. I was facing downhill with the bucket fully curled forward and the forks were partially in the ground. The tractor lurched forward and one of the metal lines that are located inside the FEL frame burst. I went to order a new line and they are backordered at Kubota, so I went to a hydraulic shop and had one made. They did a very good job of replicating the bends of the line. I replaced the line, but now the bucket curls back really slow. Everything else works fine. I disconnected and reconnected the quick disconnects and also disconnected and reconnected the rear hydraulic hose for the BH.I also crack open the lines that go to the piston for the curl and let some fluid leak out although this system doesn't need to be bled of what Kubota told me. I topped off the SUDT and have been operating the curl quite a few times to see if it would works it way out. Is it possibly that the seals in the curl pistons failed when this happened? There is only 179 hours on the machine.

The one thing I did notice, if I curl the bucket fully forward and put the edge on the ground and curl back, it will raise push the tractor back, so it still has the strength, it is just VERY slow curling back.

I'm out of ideas. I don't want to send it in for service if it is something I can fix. Any ideas? Thanks.

 

[RNeumann]

Sounds like a seal in the cylinder. I think you will need to rebuild it.

Bypass testing a hydraulic cylinder - YouTube

 

[lzicc]

I am thinking the same thing, but if it was leaking, would it have the strength to push the tractor back when I curl the bucket back under pressure?

Sounds like a seal in the cylinder. I think you will need to rebuild it.

Bypass testing a hydraulic cylinder - YouTube

 

[lzicc]

I found a dealer that has the line in stock. I ordered it. The part is $52 and shipping is $85. It's in a large box. I am going to try to replace the line that the hydraulic shop made with the OEM from Kubota and see what happens. I'm out of idea's at this point. That is the only difference.

 

[RNeumann]

The “only” difference is you over pressured the system so severely you split a steel hydraulic line.
I’d test the cylinders........

 

[lzicc]

I'm going to test them. I'm wondering if Kubota would cover this under warranty if I do let the dealer look at it? It is still under warranty until August 2019. Those steel lines are so thin walled. When I had the new line made, even the guy at the hydraulic shop said that they were very thin walled. I still want to get the OEM line on it so the dealer doesn't blame the manufactured line.

On the testing procedure, what would be a good way to cap off the line going to the cylinder I would be testing?

The ç™»nly difference is you over pressured the system so severely you split a steel hydraulic line.
I壇 test the cylinders........

 

[RNeumann]

Call your hydraulic guy who made the hose. He will have caps. But by the time you fiddle around with isolating one cylinder it may be faster to just pull them both and have them bench tested. Or use your machine to “bench test” them once they are removed.

 

[crashz]

Not sure if its covered under warranty. But it sounds to me that you had the fork tips in the ground, with the forks vertical. Any forward or reverse movement puts incredible stress on the loader and cylinders. Likely if the tractor lurched the other way, you might be replacing two bent cylinders.

If there was enough pressure to pop a metal line, there could be internal damage to the cylinders (likely) but also to your loader valve.

Best of luck.

 

[lzicc]

In a nutshell, that is exactly what happened.

Could I switch the hydraulic lines so that the raise and lower lines could operate the bucket curl just to test the cylinders? I swapped the the top 2 lines which go to the curl cylinders with the 2 lower lines that go to the raise cylinders, but didn't get the results I was looking for. Is that even possible? That may be a good test to see if the curl cylinders seals were damaged.

Not sure if its covered under warranty. But it sounds to me that you had the fork tips in the ground, with the forks vertical. Any forward or reverse movement puts incredible stress on the loader and cylinders. Likely if the tractor lurched the other way, you might be replacing two bent cylinders.

If there was enough pressure to pop a metal line, there could be internal damage to the cylinders (likely) but also to your loader valve.

Best of luck.

 

[Fallon]

In a nutshell, that is exactly what happened.

Could I switch the hydraulic lines so that the raise and lower lines could operate the bucket curl just to test the cylinders? I swapped the the top 2 lines which go to the curl cylinders with the 2 lower lines that go to the raise cylinders, but didn't get the results I was looking for. Is that even possible? That may be a good test to see if the curl cylinders seals were damaged.

Probably not. Most machines have regen or fast dump on the curl circuit. It applies full pressure to both sides of the cylinder. As the rod end is smaller than the cylinder end (the rod takes up space) the cylinder end overpowers the rod end & it extends. The extra fluid from the rod end makes the cylinder operate faster than it could otherwise. As you really dont need much power to dump thanks to gravity the power loss doesnt matter. It also keeps both ends of the cylinder pressurized so it doesnt suck in air. There are plenty of posts on TBN about floppy bucket syndrome, which is caused by sucking in air.

My old Kubota L3200 only had regen dump. My new L4060 has regen dump & then a power dump if you move the joystick all the way over. Surprisingly I rarely use or need power dump.

Because of regen you cant swap hoses. You can put a diverter on the curl circuit, but it wont run a hydraulic motor or single action cylinders, such as the 2 opposed ones on most snow plows. As the cylinders are the same size regen cant overpower one over the other. The plow will only sngle 1 way & you cant get it to ever move back the other way.

If your loader valve has power dump you could use that to test with, but you need to find out if its regen only or not.

 

[wagne223]

My guess would be you are looking at more the seal damage. Likely the rod is bent, or the piston is damaged, or both.

If that is the case, those items are probably dragging on the bore causing the slow movement.

I would have had both those cylinders torn down prior to replacing that pipe.

I recommend you do that now.

 

[lzicc]

These are my thoughts and I could be totally off. If it was bent, it would curl slow both ways. It only curls slow when I curl back. I tested the curl back under load and even though it is slow, it hasn't lost any strength or does it leak down, so that is why I am questioning the seals being bad. I seems like there is a blockage somewhere and it's got getting the fluid fast enough when curling back.

The OEM steel line will be delivered today. I want to get that on so I can get that out of the way. When the hydraulic place made the line, they had to use elbow fittings for the tight corner bend. Sometimes I wonder if that fitting is a bottleneck for the flow of fluid since it would reduce the inside diameter of the line at the elbow. I know, I am reaching.

If you look at the picture below, line 50 is the one that burst and was made by the hydraulic shop. If you look at my arrow, it points to a 90 degree bend. They could not make that bend because the fitting next to it was too close, so they used an elbow to make that bend.

 

[BukitCase]

Your comments about swapping hoses leads me to think you may have quick disconnects on your FEL lines - if so, the symptoms MIGHT indicate a broken spring inside one of the QD's - if this happens in a QD pair, they can start acting like a 1-way CHECK VALVE (albeit a "leaky" one, therefore slow instead of stop)

BTW, this is NOT "internet fact", I've personally had it happen on two different occasions in the past 10-12 years; so, not "common", but possible...

If that's what happened, it could either have been CAUSED by the overpressure (aided by faulty materials in the spring) or it could be entirely COINCIDENTAL. ("stuff happens")

You may be able to check this fairly easily by powering down, wiggling all levers multiple times, and separating the QD's one pair at a time, then pushing on the center (ball or poppet) - do NOT do this with a body part, even a powered down hydraulic system can inject fluid into your body - use a small nut driver or similar.

Once any pressure is relieved, if the ball or poppet moves without quite a bit of force (or at least DIFFERENT than its mate) you might have found your problem.

I personally am NOT a fan of REGEN, my opinion (at least for non-commercial operators) is that it's more of a PITA than a help (especially if you wanna add a diverter to that circuit). If ya can't wait a couple more SECONDS for a bucket to dump, try using a pick and shovel instead - I bet you'd change your mind pretty quick

Anyway, it's another (cheaper) thing to check that may help, definitely worth the time it takes to check it out... Steve

 

[lzicc]

I disconnect both rams from the bucket and cycled them back and forth. Both rams were both very slow moving back. What are the chances that the seals in both cylinders blew? I wonder if the issue could be in another part of the system. I did remove the QD's and was able to push the ball on both and they both reacted the same. I also visually looked at both cylinders and they both look true and straight.

 

[BukitCase]

If you can (and haven't already) swap your QD's so "curl" = "dump" (assuming regen doesn't keep that from working) - and see if "extend" becomes the slow one - this might tell you more about what/where the problem is. I've seen things come loose in hydraulic systems that can ALSO act like a check valve, and your mishap could possibly dislodged something that's been in there since manufacture, either in the control valves, an inline fitting, or??!?.

It does seem a little odd that BOTH cyls would've failed at the same time; usually the weakest link gets hammered first, but anything is possible. Remember, troubleshooting is almost ALWAYS just "finding out all the things it's NOT"... Steve

 

[oldnslo]

Iz
Have you tried feathering the curl function to see if the cylinders retract smoothly. Try slowly increasing the retract speed to see if you can or see a change in speed or in the hoses that would indicate pressure building. If yes then I would also suspect a failing quick disconnect half. Either half can fail.

Sometimes they will work at lower flows and then act like a restriction at higher flows

Seriously doubt new tune is the problem since the Dump function works correctly

 

[lzicc]

I did swap the 2 QD. Once I did that, no matter which way I pushed the lever, it would dump. Weird. I'm tempted to remove one of the lift cylinders and replace one of the curl cylinders with a lift cylinder and see if it goes back slow also. I wouldn't connect it to the bucket, just the actual hydraulic lines. I want to try to pinpoint where the issue lies. If the lift cylinder acts the same way, then I know that the curl cylinders are good and the problem lies further back in the system. In my opinion, it seems like there is blockage somewhere in the hydraulic system only for that circuit. I did check the UDT fluid level again and it is full.

If you can (and haven't already) swap your QD's so "curl" = "dump" (assuming regen doesn't keep that from working) - and see if "extend" becomes the slow one - this might tell you more about what/where the problem is. I've seen things come loose in hydraulic systems that can ALSO act like a check valve, and your mishap could possibly dislodged something that's been in there since manufacture, either in the control valves, an inline fitting, or??!?.

It does seem a little odd that BOTH cyls would've failed at the same time; usually the weakest link gets hammered first, but anything is possible. Remember, troubleshooting is almost ALWAYS just "finding out all the things it's NOT"... Steve

 

[lzicc]

I can try that tonight.The cylinder does move smooth, it's just very slow.

Iz
Have you tried feathering the curl function to see if the cylinders retract smoothly. Try slowly increasing the retract speed to see if you can or see a change in speed or in the hoses that would indicate pressure building. If yes then I would also suspect a failing quick disconnect half. Either half can fail.

Sometimes they will work at lower flows and then act like a restriction at higher flows

Seriously doubt new tune is the problem since the Dump function works correctly

 

[ruffdog]

I did swap the 2 QD.

Have you tried switching the loader lift QD's with the loader curl QD's? It might tell you if the problem is the valve end or the bucket end.

 

[lzicc]

I tried that too and it didn't work right so I could not tell.

Have you tried switching the loader lift QD's with the loader curl QD's? It might tell you if the problem is the valve end or the bucket end.