Grapple problems

[Nc995]

Can anyone help with a grapple on my L4802?

I’ve used grapples pretty extensively on skid steers but never ran into the problems I am having here.

The grapple will function flawlessly while I am sitting, but when I go to close on a load it will open violently and smash into the cylinders on my loader. It’s also opening much wider than normal when it does this. Back off the load (and replace busted fittings and etc) and it works fine again…until it doesn’t. The grapple goes out of synch, too where attempting to close opens one and closes the other and vice versa.

I’m pulling my hair out here trying to figure out what’s wrong.

 

[bradley martin]

Is this a new setup or a new development on an existing machine? Factory or your own mounting and hydraulic tie in. With the information given, my thought would be it is tapped into an incorrect hydraulic circuit.

 

[Jim.ME]

Can anyone help with a grapple on my L4802?

I’ve used grapples pretty extensively on skid steers but never ran into the problems I am having here.

The grapple will function flawlessly while I am sitting, but when I go to close on a load it will open violently and smash into the cylinders on my loader. It’s also opening much wider than normal when it does this. Back off the load (and replace busted fittings and etc) and it works fine again…until it doesn’t. The grapple goes out of synch, too where attempting to close opens one and closes the other and vice versa.

I’m pulling my hair out here trying to figure out what’s wrong.

L4802 is 2022 or newer isn't it? Electric valve or separate third function spool? Dealer installed, OEM set up? If so, it might be time to talk to the dealer.

 

[Nc995]

Is this a new setup or a new development on an existing machine? Factory or your own mounting and hydraulic tie in. With the information given, my thought would be it is tapped into an incorrect hydraulic circuit.

The tractor is brand new. Dealer installed third function.

 

[Nc995]

L4802 is 2022 or newer isn't it? Electric valve or separate third function spool? Dealer installed, OEM set up? If so, it might be time to talk to the dealer.

Electric valve, dealer installed.

 

[Jim.ME]

The tractor is brand new. Dealer installed third function.

Brand new tractor, with dealer installed option. I would suggest talking to the dealer and see what can be worked out., before asking for ideas on a forum to avoid the risk of losing a warranty claim.

 

[Nc995]

Brand new tractor, with dealer installed option. I would suggest talking to the dealer and see what can be worked out., before asking for ideas on a forum to avoid the risk of losing a warranty claim.

The grapple isn’t from the dealer and why I wanted to see if anyone had ideas.

 

[Jim.ME]

The grapple isn’t from the dealer and why I wanted to see if anyone had ideas.

The grapple isn’t from the dealer and why I wanted to see if anyone had ideas.

Ok, that was a bit of info that would have been good to have in your first post.

What type of grapple is this? Is the grapple a quick attach mount type, which mounts in place of the bucket, that matches your loader, then you just hook up the two hoses for the open and close cylinder(s)? Or is it a grapple and cylinders that you installed on the loader's bucket? Erratic operation can be air in the system. Have fully cycled the grapple a number of times to clear all air and checked the oil reservoir level of the tractor? The dealer didn't install the grapple but did install the third function valve and controls, is this correct? If so, the problem sounds like it could be in the third function, which you say the dealer installed. Still sounds like you should talk to the dealer and see what they say, before tearing into anything they installed.

If the design of the grapple (of either type) is such that if it can hit your tractor cylinders and hoses when it fully opens, that sounds like a design or mounting issue with the grapple or a mismatch between that model grapple and the tractor/bucket. I can see if the grapple tips way back when fully open, you might have roll back enough on the bucket cylinders that the back side of the open grapple might contact the loader.

 

[farmersamm]

Built a grapple years ago, and ran into something somewhat similar. Violent cylinder movement.

You probably need a flow restrictor on those lines. It slows it down.

Chances are.........you'll need to fine tune the orifice. I drilled mine out a bit to allow more flow.

As far as both cylinders not reacting at the same time. It's normal. Unless all lines are equal length(and sometimes that doesn't really work well), like diesel injector lines. it will never operate in tandem. Or.....you can spend a ton of money to do it with flow control.........which isn't necessary.

 

[Nc995]

Ok, that was a bit of info that would have been good to have in your first post.

What type of grapple is this? Is the grapple a quick attach mount type, which mounts in place of the bucket, that matches your loader, then you just hook up the two hoses for the open and close cylinder(s)? Or is it a grapple and cylinders that you installed on the loader's bucket? Erratic operation can be air in the system. Have fully cycled the grapple a number of times to clear all air and checked the oil reservoir level of the tractor? The dealer didn't install the grapple but did install the third function valve and controls, is this correct? If so, the problem sounds like it could be in the third function, which you say the dealer installed. Still sounds like you should talk to the dealer and see what they say, before tearing into anything they installed.

If the design of the grapple (of either type) is such that if it can hit your tractor cylinders and hoses when it fully opens, that sounds like a design or mounting issue with the grapple or a mismatch between that model grapple and the tractor/bucket. I can see if the grapple tips way back when fully open, you might have roll back enough on the bucket cylinders that the back side of the open grapple might contact the loader.

It’s a skid steer mount with QA hoses. Have cycled open and closed several times, and tractor is up on oil.

As far as hitting the tractor, it’s only when it gets crazy on me. It doesn’t normally open near far enough to come near the tractor. Its those random slam wide open moments when it’s supposed to be closing that cause a problem.

Very frustrating.

I found the install instructions for the third function buried in my papers. I think I’ll give it a peek tomorrow and see if anything stands out. I don’t plan to tear into anything, just never seen symptoms like this and was wondering if I could be missing something.

 

[Nc995]

Built a grapple years ago, and ran into something somewhat similar. Violent cylinder movement.

View attachment 83853

You probably need a flow restrictor on those lines. It slows it down.

View attachment 83854

Chances are.........you'll need to fine tune the orifice. I drilled mine out a bit to allow more flow.

As far as both cylinders not reacting at the same time. It's normal. Unless all lines are equal length(and sometimes that doesn't really work well), like diesel injector lines. it will never operate in tandem. Or.....you can spend a ton of money to do it with flow control.........which isn't necessary.

Useful info on the flow restrictor. I’m not accustomed to push buttons other than on/off of hydraulic brush cutters and such.

As for the grapple not being in synch, it’s not a matter of them not closing in time with one another - which I’d agree is normal - but of one closing and the other slamming violently open at the same time. That’s the part that doesn’t make me think it’s the tractors third function causing it.

 

[Jim.ME]

This doesn't answer why it is violent at times, however it does not make sense that it only hits the loader when the cylinders react violently. It the grapple cannot reach the loader if you fully run the cylinders to full stroke when under control, not being stopped by you before the grapple reaches the loader because you have control, it should not hit the loader when it is violent (unless there is a lot of pin slop). Having cylinder stroke enough to let the grapple hit the loader and damage hose and fittings is a design issue whether functioning correctly or violently.

How about a couple pictures. If the grapple is one piece for both cylinders to act on, the cylinders should stay in sync. If you decide to try restricting it, you may want to look into adjustable flow restrictors. That way you can change flow rates without disassembling lines and redrilling orifices inside fittings.

What type of thrid function set up is it? Just an electric valve that puts system flow (all or nothing) to the third function or one that diverts the flow from the bucket cylinder valve to the grapple, so you have feathering control with the bucket valve lever?

 

[Nc995]

This doesn't answer why it is violent at times, however it does not make sense that it only hits the loader when the cylinders react violently. It the grapple cannot reach the loader if you fully run the cylinders to full stroke when under control, not being stopped by you before the grapple reaches the loader because you have control, it should not hit the loader when it is violent (unless there is a lot of pin slop). Having cylinder stroke enough to let the grapple hit the loader and damage hose and fittings is a design issue whether functioning correctly or violently.

How about a couple pictures. If the grapple is one piece for both cylinders to act on, the cylinders should stay in sync. If you decide to try restricting it, you may want to look into adjustable flow restrictors. That way you can change flow rates without disassembling lines and redrilling orifices inside fittings.

What type of thrid function set up is it? Just an electric valve that puts system flow (all or nothing) to the third function or one that diverts the flow from the bucket cylinder valve to the grapple, so you have feathering control with the bucket valve lever?

I cannot make it hit the loader under normal operation.

When it springs open violently on CLOSE, it’s not only doing so much further than normal operation and with some slop in the pins, but also when impossible to anticipate because it is random and unpredictable.

But yeah - I understand grapples shouldn’t hit the loader.

 

[flying belgian]

The tractor is brand new. Dealer installed third function.

If the dealer installed it I wouldn't touch anything. take it back to dealer.

 

[Nc995]

If the dealer installed it I wouldn't touch anything. take it back to dealer

I think you all have satisfactorily hammered home the point of not tearing apart a 3 day old fully warranteed tractor.

The grapple is not from a dealer, not under warranty, and they aren’t going to troubleshoot or repair it.

 

[Jim.ME]

I think you all have satisfactorily hammered home the point of not tearing apart a 3 day old fully warranteed tractor.

The grapple is not from a dealer, not under warranty, and they aren’t going to troubleshoot or repair it.

The grapple is not powered, its movements are controlled and powered the tractor valve.

Is there someone you know near you that has a tractor or skid steer you could try the grapple on? If the same symptoms occur with the grapple on the second unit there is a problem in the grapple, not the dealer's problem. If the grapple operates without acting up on on a different tractor, the issue is in your tractor hydraulics or valves, the dealer's to find.

Does your tractor have a set of remote couplers? You could try using those remotes to run the grapple and see how it works.

 

[Nc995]

The grapple is not powered, its movements are controlled and powered the tractor valve.

Is there someone you know near you that has a tractor or skid steer you could try the grapple on? If the same symptoms occur with the grapple on the second unit there is a problem in the grapple, not the dealer's problem. If the grapple operates without acting up on on a different tractor, the issue is in your tractor hydraulics or valves, the dealer's to find.

Does your tractor have a set of remote couplers? You could try using those remotes to run the grapple and see how it works.

I’ve used the grapple before on a different skid steers without issue, but it’s been a while.

My reason in posting is this was thinking that perhaps there may be an issue with bleeding. That’s what it seems like to me. My thoughts are that the cylinders are small and with a short stroke, and there’s fairly long lines between the cylinders and tractor, and again long lines down the loader.

What I didn’t anticipate is that from this question everyone would conclude from the model number that it must be returned to the dealer. I don’t actually think there’s anything dysfunctional with the third function. It’s for sure worth considering, but there’s just no malfunction that I can think of that might explain one arm closing while the other directly connected wildly flips open…only sometimes.

 

[Jim.ME]

I’ve used the grapple before on a different skid steers without issue, but it’s been a while.

My reason in posting is this was thinking that perhaps there may be an issue with bleeding. That’s what it seems like to me. My thoughts are that the cylinders are small and with a short stroke, and there’s fairly long lines between the cylinders and tractor, and again long lines down the loader.

What I didn’t anticipate is that from this question everyone would conclude from the model number that it must be returned to the dealer. I don’t actually think there’s anything dysfunctional with the third function. It’s for sure worth considering, but there’s just no malfunction that I can think of that might explain one arm closing while the other directly connected wildly flips open…only sometimes.

People conclude it needs to go back to the dealer given it is a new tractor. You said you have used grapples before on skid steers, you did not say you have used this grapple on skid steers before. What was written left me with the impression it was a new tractor with a third function and grapple, purchased as a unit, thus the first step would be to contact the dealer to protect the chance for a warranty claim.

If it was run on other units before, connected with quick couplers, one would expect the grapple cylinders would be already bled out so the only air would be in the loader/tractor side, which would be minimal and would have been purged after a few cycles. Even if you had drained the grapple hydraulic cylinders and hoses before installing it on your tractor, it should have self-bled after a few full stoke cycles, which should have been done before working it.

In your last post here, it sounds like you have two, or more, cylinders operating independent parts of the grapple. We can't see your set up. Post some pictures of the grapple and a sketch of how you have it plumbed. That may help.

 

[Nc995]

People conclude it needs to go back to the dealer given it is a new tractor. You said you have used grapples before on skid steers, you did not say you have used this grapple on skid steers before. What was written left me with the impression it was a new tractor with a third function and grapple, purchased as a unit, thus the first step would be to contact the dealer to protect the chance for a warranty claim.

If it was run on other units before, connected with quick couplers, one would expect the grapple cylinders would be already bled out so the only air would be in the loader/tractor side, which would be minimal and would have been purged after a few cycles. Even if you had drained the grapple hydraulic cylinders and hoses before installing it on your tractor, it should have self-bled after a few full stoke cycles, which should have been done before working it.

In your last post here, it sounds like you have two, or more, cylinders operating independent parts of the grapple. We can't see your set up. Post some pictures of the grapple and a sketch of how you have it plumbed. That may help.

The point of saying “grapples” was that I have operated many of them and never seen this behavior. I’ve torn lines, rebuilt cylinders, and never seen anything like this. Usually a couple strokes and it’s in business. This one has been cycled hundreds of times and still has totally random misbehavior.

The plumbing is about as simple as can be..a line from the QD to a T then to the bottom of each cylinder, and another from the QD to a T to the glad-end of each cylinder.

 

[used red MN]

Hello Nc995, welcome to YT! First I know nothing about Kubota hydraulics of at least things associated with You say the valve is electric are the other remote valves also electric? You took it to a dealer and they installed the 3rd valve. I assume they operated to grapple.
My guess is that they found that the cylinder was moving very fast so they has to adjust the flow of the remote valve. It seems like whatever system is supposed to regulate the flow out of that remote is failing or is inconsistent during operation. I think that Farmersamm by have your answer.