Need grapple hydraulic help

[fixitman123]

I have a single lid grapple attached to my tractor. I used the rear hydraulic hookup to operate the grapple lid. Worked fine first couple days of use. When I was about through working the other day when I noticed that the lid was closing slowly. I switched hoses on the rear hookup and it still does the same just the controls are reversed. This tells me it's not the tractor. I removed hoses from the cylinder and worked it in and out to check for an obstruction and it seemed to work ok. Took front hoses apart and blew them and the connections out with compressed air and everything was clear. Put everything back together and still does same thing. Lid will close slowly but you can lift it open by hand (no hydraulic pressure holding it closed.). Is this a problem with the cylinder? If so how do you disassemble and repair? Thanks for any help.

 

[PHPaul]

My first guess would be air in the lines. If that's the case, it should work it's way out after a few cycles of the cylinder.

Also, check the hydraulic fluid level in your tractor. It's possible that filling the lines and the cylinder dropped your level in the tractor far enough to be an issue.

 

[RNeumann]

Is The control valve in the neutral/closed/center position when you are able to lift the grapple manually? Do you have anything else to hook the hydraulic lines to-log splitter or anything else to test the tractor hydraulics? With the grapple open and at 90° to the ground and the tractor off does the grapple drift down- drifting down would indicate a valve problem.
Start with the basics listed above and then move through these questions.

 

[fixitman123]

My first guess would be air in the lines. If that's the case, it should work it's way out after a few cycles of the cylinder.

Also, check the hydraulic fluid level in your tractor. It's possible that filling the lines and the cylinder dropped your level in the tractor far enough to be an issue.

It worked fine for most of a day then started acting up. Fluid level is ok.

 

[fixitman123]

Is The control valve in the neutral/closed/center position when you are able to lift the grapple manually? Do you have anything else to hook the hydraulic lines to-log splitter or anything else to test the tractor hydraulics? With the grapple open and at 90° to the ground and the tractor off does the grapple drift down- drifting down would indicate a valve problem.
Start with the basics listed above and then move through these questions.

Yes the lever is in the center position. When grapple is open and lever is centered I can't close it by hand. I'll have to see if it drifts down tomorrow.
I don't have anything with a cylinder I can test with.

 

[kennyd]

Sounds like the seals are blown in the cylinder, or the piston came off the rod. You'll have to post pics of the cylinder before we can advise how to disassemble and fix it.

Where you pushing with the lid maybe? That can put incredible stress on the cylinder and lines.

 

[fixitman123]

Sounds like the seals are blown in the cylinder, or the piston came off the rod. You'll have to post pics of the cylinder before we can advise how to disassemble and fix it.

Where you pushing with the lid maybe? That can put incredible stress on the cylinder and lines.

No I wasn't pushing with the lid. The grapple had only been used for a couple days when it started acting up. I'll post pics of the cylinder tomorrow. Thanks

 

[kennyd]

Is it new? If so contact the maker.

 

[ovrszd]

Open the Grapple. Then unplug the hoses. See if it drifts closed.
This will separate the cylinder from the tractor valves and will give you a better idea where the problem might be.

Another test, if the couplers are the same, would be to unplug the FEL Curl function hoses and plug your Grapple into that circuit. Test operation. This again would indicate cylinder problem or valve problem.

 

[RNeumann]

Sounds like the seals are blown in the cylinder, or the piston came off the rod. You'll have to post pics of the cylinder before we can advise how to disassemble and fix it.

Where you pushing with the lid maybe? That can put incredible stress on the cylinder and lines.

Ditto regarding seals

Good idea to see if FEL and Grapple quick connects are the same- that would make for an easy test

BTW isolating the cylinder from the valve won't tell if the cylinder is bad. Because of the rod, even if the piston had no seals, you can't add "rod" to a full cylinder- their is no room. Read up and learned this one a few weeks ago.

Lifting the grapple to 90° and seeing if it drifted down quickly could indicate a bad valve.

Testing the cylinder involves installing valves and pressure gauges on either side of the piston and reading the pressure difference over time.

 

[ovrszd]

Ditto regarding seals

BTW isolating the cylinder from the valve won't tell if the cylinder is bad. Because of the rod, even if the piston had no seals, you can't add "rod" to a full cylinder- their is no room. Read up and learned this one a few weeks ago.

Lifting the grapple to 90° and seeing if it drifted down quickly could indicate a bad valve.

Testing the cylinder involves installing valves and pressure gauges on either side of the piston and reading the pressure difference over time.

His drift is pulling the rod out of the cylinder.

 

[RNeumann]

His drift is pulling the rod out of the cylinder.

Ok I'm about to learn something new- please expand

 

[ovrszd]

On a Grapple the cylinder extends to close. Collapses to open. His drift is toward closing. So rod is moving out of cylinder barrel rather than into. It's possible for that to happen.

 

[fixitman123]

Open the Grapple. Then unplug the hoses. See if it drifts closed.
This will separate the cylinder from the tractor valves and will give you a better idea where the problem might be.

Another test, if the couplers are the same, would be to unplug the FEL Curl function hoses and plug your Grapple into that circuit. Test operation. This again would indicate cylinder problem or valve problem.[/QUOTE


Can only get one line to disconnect with pressure on the line. FEL connects are different.

 

[fixitman123]

With lever actuated to close lid it closes real slow but can be closed faster using my hands. Only with the lever actuated. Can't close by hand without the lever actuated. Would really like to isolate it to the cylinder before trying to tear it apart.

 

[RNeumann]

So it sounds like the valve is good. Without being able to move/switch hydraulic hoses it is difficult to give a definitive answer but everything is pointing toward the cylinder from what you describe.
Bench testing a cylinder requires a couple of gauges and shutoff valves. But removing the cylinder from the grapple shouldn't be too hard and someone around you I'm assuming can help if you don't want to open it up.

To get pressure off everything to disconnect lower everything to the ground and shut off tractor. Then run the valves in all directions this should release the pressure enough to disconnect.

 

[ch1ch2]

I had similar problems with my grapple.
I have 3 rear remotes. I moved the connection a round several times, trying to find which one worked the best. Ended up getting longer hoses for my hydraulic top link. The movement of the top link was moving the grapple hoses to the point of causing them to disconnect.
I am sure that is not your problem, but thought it might be worth mentioning in case it is something your over looking.
You have some very knowledgeable help already helping you.
Listen to them and you will be able to work it out.

 

[RNeumann]

Got it regarding closed is extended. I should have stated "add or subtract"

The Root Cause of Hydraulic Cylinder Drift

 

[ovrszd]

So it sounds like the valve is good. Without being able to move/switch hydraulic hoses it is difficult to give a definitive answer but everything is pointing toward the cylinder from what you describe.
Bench testing a cylinder requires a couple of gauges and shutoff valves. But removing the cylinder from the grapple shouldn't be too hard and someone around you I'm assuming can help if you don't want to open it up.

To get pressure off everything to disconnect lower everything to the ground and shut off tractor. Then run the valves in all directions this should release the pressure enough to disconnect.

Sounds like you've got this so I'll step out.

 

[RNeumann]

Sounds like you've got this so I'll step out.

I just read up on this a few weeks ago so it's new to me. Only thing I have is an ability to repeat stuff.....haha

Actually your idea about the FEL quick connects is what I'd do to test it- even if he has to unthread a few fittings.