Add a Double Pilot Check valve to Side Link Cylinder?

[MtnViewRanch]

Thanks for all the input. Let me fill you in on where I've been and where I'm trying to go.
My lane is 3/4 miles up and down along a river. Constant maintenance required. I had a Kubota L3600 with a single factory rear remote and a Monroe 7' HD backblade with a cylinder to rotate it(HEAVY). I added a 3 solenoid valve block plumbed off of the single rear remote. Initially used one position to operate an hydraulic top link and a second one to rotate the backblade. Bought an hydraulic side link through the dealer to allow me to tilt the blade for ditching along and crowning the lane. The cylinder would drop 3 or 4 inches in 10 minutes. Assuming the problem was the cylinder, they dealer gave me a replacement. Still leaked down so I gave up and abandoned it.




I've since replaced the tractor with a Kubota L5240 HSTC equipped with 2 rear remotes so I can operate the top link and blade rotation. Decided to try the side link (kept it when I sold the first tractor--not intensionally--forgot it). Turns out the L5240 has a smaller pin in the upper end of the side link, so I need to determine the right size and replace the upper ball end on the cylinder before I can determine if it can hold up the blade using the remotes on the newer tractor. Does anyone know a source for a new weld on ball end and the correct size for this 5240? The L3600 used a 7/8" pin, but the L5240's pin is smaller and uses locking nuts rather than a pin as a retainer.
Reading through all your responses leads me to conclude that the problem with the original setup was in either the remote on the L3600 or the solenoid diverter block. I want to confirm that the side link will perform satisfactorily through the L5240's remotes. If so, there'd be no need to add a check valve to the cylinder. If I can make this work I may spend the horrendous $ Kubota wants for the kit to add the 3rd remote.
Thanks again for your help. Now I need to find a source for the correct ball end for my cylinder.

Easiest thing to do is to just bush it down in size. I think that you will find that if your side link was the right size working length for your L3600, it is not the right working length for your L5240. Not saying that it won't work, just that it will not be right. You probably can make up the difference by using different pin locations in the lower clevis and use the manual adjust on the left side and dial it in that way.

 

[ovrszd]

Brian , good job of defending your position with logic concerning valve leakage versus cylinder leakage. They dogpiled you for awhile but you prevailed. Heheheh.

 

[kcoburn]

Brian,
Thanks for the suggestion.
You are correct. It's not perfect choice for this tractor, but the dimensions are adequate to work for my purposes. I had the cylinder on the tractor last fall. The difference in pin size is so small that I don't think I can find a bushing thin enough. Do you happen to know the O.D. of the pin used on my tractor L5240HSTC? Still have my snow removing armor on the tractor including the back blade or I'd pull it out and measure. Feel like a real deadbeat asking this of a man who makes and sells sidelink kits and I'm trying to cobble up one I already have.

 

[MtnViewRanch]

Brian,
Thanks for the suggestion.
You are correct. It's not perfect choice for this tractor, but the dimensions are adequate to work for my purposes. I had the cylinder on the tractor last fall. The difference in pin size is so small that I don't think I can find a bushing thin enough. Do you happen to know the O.D. of the pin used on my tractor L5240HSTC? Still have my snow removing armor on the tractor including the back blade or I'd pull it out and measure. Feel like a real deadbeat asking this of a man who makes and sells sidelink kits and I'm trying to cobble up one I already have.

You should be able to get a bronze bushing that goes from 7/8" down to 3/4". Honestly, my guess is that the L3600 had a 3/4" pin also. Your dealer probably bought a Tisco unit and that is what size pin hole it came with. They just put it on and thought you were good to go. But that is all just supposition. Kubota jumps up to the 7/8" pin size with the M models.

 

[J_J]

Brian , good job of defending your position with logic concerning valve leakage versus cylinder leakage. They dogpiled you for awhile but you prevailed. Heheheh.

Oh, you really think so. You assume to much. He He.

So you think they make hyd valves inferior to cyl and charge more for the valves on purpose.

It 's not about someone getting something over anybody else, it is about what one knows and have seen.

Have you seen data backing up either theory, as to whether the cyl is giving the most problem or the valve.

It would really pi** the manufactures/dealers off to be replacing a lot hyd valves.

Maybe one can correlate the ability for a loader to raise and keep the bucket up for weeks or months to either the cyl or the valve.

It is real easy to test the valve by installing a shutoff valve in the work port to the base end of the cyl.

Raise the attachment , shut off the valve and see what happens. If the cyl retracts, then you know it is the cyl.

If the cyl does not retract, then the cyl is presumed good. Now, open the valve and wait, and see if the loader will descend, and if it does, then the valve is leaking.

You can either test using the faulted hyd components you have or use known good parts.

There are other ways to test, and people should fully trouble shoot before jumping to conclusions.

 

[ovrszd]

Oh, you really think so. You assume to much. He He.

So you think they make hyd valves inferior to cyl and charge more for the valves on purpose.

It 's not about someone getting something over anybody else, it is about what one knows and have seen.

Have you seen data backing up either theory, as to whether the cyl is giving the most problem or the valve.

It would really pi** the manufactures/dealers off to be replacing a lot hyd valves.

Maybe one can correlate the ability for a loader to raise and keep the bucket up for weeks or months to either the cyl or the valve.

It is real easy to test the valve by installing a shutoff valve in the work port to the base end of the cyl.

Raise the attachment , shut off the valve and see what happens. If the cyl retracts, then you know it is the cyl.

If the cyl does not retract, then the cyl is presumed good. Now, open the valve and wait, and see if the loader will descend, and if it does, then the valve is leaking.

You can either test using the faulted hyd components you have or use know good parts.

There are other ways to test, and people should fully trouble shoot before jumping to conclusions.

JJ it's much easier to test the cylinder which was repeatedly explained by Brian. Maybe you didn't hear him because of the commotion during the dogpile. Heheheh.

No manufacturer wants to admkt the factory valve is to blame versus the aftermarket cylinder.......

 

[oldnslo]

A basic fact of life is that ALL spool valves leak unless they are equipped with check valves. The amount of leakage varies depending on several variables some of which are: roundness of the spool bore, roundness of the spool, diametrical clearance between spool and bore, overlap of spool land on the valve body, oil viscosity, pressure, etc.

I have found very few valve manufacturer's that document valve leakage.

The reason valves are rarely replaced is they are hardened parts that typically don't get damaged or scarred unless some large debris gets caught in them where as seals are wearing components designed to sacrifice themselves to seal. Rubber seals by deforming into or conforming to the mating surface, I.e. cylinder bore which even when honed is not smooth. Typical worst case seal wear is at break away under load. This is when the seal is sitting static under load (pressure) and has conformed to all the minor irregularities in the bore. When first movement occurs there is a chance for very small fragments of the seal to be torn off.

JJ & Others

With a load on an extended cylinder and the blind end port blocked, & if there is NO leakage path out the rod end you can remove the piston seals and the cylinder won't retract. Some times suggested tests are solving the problem either.

 

[kcoburn]

I've ordered a bushing so I can hang this side link on the newer tractor. When I get to it, I'll install it and see if it still leaks down quickly. If it does, I'll see if I can determine if the valve or cylinder is at fault and report back. We can't leave this discussion just "hanging out there".
Thanks for all the help.

 

[oldnslo]

KCOburn,
If it leaks down please measure the actual cylinder drift over time not the implement movement. due to the geometry of the 3 point hitch arms in relation to implement width a a 1/4" of cylinder drift could be inches of implement movement.

good luck

 

[ovrszd]

We can't leave this discussion just "hanging out there".
Thanks for all the help.

That's a good one!!!! Glad to see you have a sense of humor about it!!!

 

[kcoburn]

I installed the cylinder on the L5240 using the factory remotes. Hung the big old back blade up in the air and measured the cylinder's rod position. Let it hang there for an hour. The rod pulled out roughly 9/16"--nothing like the drop I used to get using the cylinder on the older tractor with the remote through the 3 solenoid valve block. Disconnected the couplers from the valve and let the blade hang for another hour. Hard to tell for certain but the rod may have dropped another 1/16". Brian-you were right. The problem I had with the cylinder was largely a result of the cobbled up valving system, not the cylinder itself. Adding the check valve to the cylinder would have done little or nothing for me.
Thanks again for your help.

 

[bandaidmd]

"Adding the check valve to the cylinder would have done little or nothing for me."

9/16" drop at the cylinder is still a significant amount at the blade tip so its likely it still would have been worth the investment.

I will be adding one to mine at some point.

 

[kcoburn]

That 9/16" drop was over an hour. With my old setup I'd get that amount of drop in a minute or two. The fact that it dropped 1/16" or less with the hoses disconnected indicates the drop is almost all a result of valve leakage, not cylinder leakage. The check valve on the cylinder will do nothing for the remote valve leakage if I understand it correctly.

 

[MtnViewRanch]

That 9/16" drop was over an hour. With my old setup I'd get that amount of drop in a minute or two. The fact that it dropped 1/16" or less with the hoses disconnected indicates the drop is almost all a result of valve leakage, not cylinder leakage. The check valve on the cylinder will do nothing for the remote valve leakage if I understand it correctly.

Actually it is just the opposite. The check valve takes care of a faulty valve, because it isolates the valve problem from the cylinder. It will do nothing for a faulty cylinder. So it would have eliminated the drop and would still do so with your current set up. Do you have the float function with your current rear remotes? If so, the existing drop rate would be livable for me. Try a different set of rear remotes if you have them, just to see. I know that on my own tractors, all the valves do not hold the same.

 

[kcoburn]

Brian,
I can live with the little leakage that I get with the current setup.
I apparently misunderstood what the check valves on the cylinder does. I thought it prevented fluid internal leakage from one end of the cylinder to the other. If I understand what you're saying, it prevents movement of fluid from one end of the cylinder to the other that occurs back through the valve. Do I have that right?

 

[MtnViewRanch]

Brian,
I can live with the little leakage that I get with the current setup.
I apparently misunderstood what the check valves on the cylinder does. I thought it prevented fluid internal leakage from one end of the cylinder to the other. If I understand what you're saying, it prevents movement of fluid from one end of the cylinder to the other that occurs back through the valve. Do I have that right?

Actually what it does is stop any fluid from simply leaking through the valve back into the system, not just back into the cylinder. If you are good with that amount of drift, then you are GOOD TO GO. :thumbsup: If you use your setup mostly for grading, then you make adjustments often enough that it usually won't matter. If you are doing chores that require the same setting ALL DAY LONG, then it can be bothersome to some.

 

[ovrszd]

If you use your setup mostly for grading, then you make adjustments often enough that it usually won't matter. If you are doing chores that require the same setting ALL DAY LONG, then it can be bothersome to some.

Well stated. I never notice my drift until I put on the brush cutter. Then I have to correct periodically or leave an unlevel cut. If I'm using the brush cutter for long periods of time, day or more, I remove my tilt cylinder and install the factory link.

 

[MtnViewRanch]

Well stated. I never notice my drift until I put on the brush cutter. Then I have to correct periodically or leave an unlevel cut. If I'm using the brush cutter for long periods of time, day or more, I remove my tilt cylinder and install the factory link.

While this is probably the best thing to do, most likely all that you need to do is unplug the hoses and the side link would stay put.

 

[ovrszd]

While this is probably the best thing to do, most likely all that you need to do is unplug the hoses and the side link would stay put.

Yep, I agree. I'm a bit OCD about things like this and not sure I could live with looking at the hoses hanging...

I carry my factory link and it's pretty easy to swap out.

But, with all that said, I totally agree that the cylinder would mostly likely stay put if unplugged.

 

[MtnViewRanch]

Come on now, there has to be a place at the back of your tractor where you could nicely lay the hoses. :confused3: But then again, that is also why I agreed with you about just changing the links out. :thumbsup: Not really a good idea to have loose hoses about when mowing.