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Discussion Starter · #1 ·
I bought this directional control valve, it came open center and I need it to be closed center. It says in the booklet I need a closed center plug, but it’s not clear on where to put it. Attached are photos of how I have it hooked up now, open center.
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Not easy to see but left. side under quick connect is the pump side and right is tank side, do I have to move the tank side to the top and plug the one it’s in? Here is the valve model:
Thanks!
 

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Welcome to MTF!

What make and model of tractor?

I'm not so sure that there is a provision for a closed center plug on that valve set. We need a link to wherever you purchased the valve set.
 

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Discussion Starter · #3 ·
Welcome to MTF!

What make and model of tractor?

I'm not so sure that there is a provision for a closed center plug on that valve set. We need a link to wherever you purchased the valve set.
I included a link to the valve, it says in the specs that it can be converted to closed center. The tractor is a kubota L3450 from 1993
 

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Discussion Starter · #4 ·
Welcome to MTF!

What make and model of tractor?

I'm not so sure that there is a provision for a closed center plug on that valve set. We need a link to wherever you purchased the valve set.
As far as I can tell the manufacturers say to put the tank side line on the top right beside where it is now and to plug the one it’s currently in.
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According to the information that I have access to, the Kubota L3450 uses an open center hydraulic system. The closed center plug will cause problems in an open center system.
 
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Discussion Starter · #6 ·
According to the information that I have access to, the Kubota L3450 uses an open center hydraulic system. The closed center plug will cause problems in an open center system.
Will it? I have it hooked up now open center, so basically it’s running double open center and has no power to either remotes or bucket. However, when I disconnect the bucket quick connects I have good power to remotes. As far as I understand, the reason I have no power to either is because the fluid would rather flow through the open center of the opposite valve than lift bucket or whatever. Path of least resistance and all that. I was told that if I made the remotes closed center I would have power to the bucket because it can no longer just flow through the valve, and if I add an inline valve to shut off hydraulics to the bucket I will have power to the remotes. Not both at the same time though which is fine with me, I just need to have one at a time. This is literally my first time doing this. I did some research as well as my brother has significant experience on hydraulics, he told me this was the right way to do it. Please explain why it would be problematic to make it closed center, I want to do this the right way
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Discussion Starter · #7 ·
Will it? I have it hooked up now open center, so basically it’s running double open center and has no power to either remotes or bucket. However, when I disconnect the bucket quick connects I have good power to remotes. As far as I understand, the reason I have no power to either is because the fluid would rather flow through the open center of the opposite valve than lift bucket or whatever. Path of least resistance and all that. I was told that if I made the remotes closed center I would have power to the bucket because it can no longer just flow through the valve, and if I add an inline valve to shut off hydraulics to the bucket I will have power to the remotes. Not both at the same time though which is fine with me, I just need to have one at a time. This is literally my first time doing this. I did some research as well as my brother has significant experience on hydraulics, he told me this was the right way to do it. Please explain why it would be problematic to make it closed center, I want to do this the right way
Thanks!
I T’d it off from before it goes to the valve of the bucket like so
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According to the information that I have access to, the Kubota L3450 uses an open center hydraulic system. The closed center plug will cause problems in an open center system.
Teeing open center control valve inlet/outlet WILL NOT ALLOW control valve to operate correctly such as a L3450. I agree with TUDOR closed center valve will not operate correctly on open center hyd system. Open center hyd control valve needs to have supply oil flowing through valve housing when pump gears are rotating.
 

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Discussion Starter · #9 ·
Teeing open center control valve inlet/outlet WILL NOT ALLOW control valve to operate correctly such as a L3450. I agree with TUDOR closed center valve will not operate correctly on open center hyd system. Open center hyd control valve needs to have supply oil flowing through valve housing when pump gears are rotating.
But I’m confused, the original hydraulics will stay open center, I don’t get how making a closed center remote will affect that. The gear pump will still be able to constantly pump oil through the open center of the original valve
 

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But I’m confused, the original hydraulics will stay open center, I don’t get how making a closed center remote will affect that. The gear pump will still be able to constantly pump oil through the open center of the original valve
What part of ""closed center control valve"" wasn't designed to operate on an ""open center hyd system"" do you not understand?? Also open center control valve should be attached to hyd system in ""series not teed into system"? Hyd oil in hyd system will take the path of least resistance which will be the ""TEE"". On closed center hyd valve the oil flow terminates at the control valve until control lever is moved allowing hyd oil to continue on it's path.
 

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You need a power beyond kit for the first valve set of the system after the pump, not a closed center plug for the second valve set of the system. Lose the Tee fittings so that the power beyond port can be daisy chained directly to the supply side of the valve set in question and your issues will be solved.

Note that things like closed center plugs and power beyond kits are specific to the valve set in question and are not universal. From your description, the valve set on your tractor does not appear to already have a power beyond kit installed and you will need to go either to the Kubota dealer or a hydraulics shop (with the make and model number) to get one to install yourself. The Tee fittings are allowing alternative paths of least resistance through the open center of the tractor's valve set or the open center of the auxiliary valve set at any time that the other valve is selected.

Correct the plumbing as indicated above.

From the first pic that you posted, it appears that the added valve set is used to control a one way cylinder, and is plumbed incorrectly for even that task. The supply line connects to the unused quick connect and the ports in line with the valve handle are for the cylinder port(s). As plumbed, it won't work for 2-way cylinders. Valve sets made for one way cylinders do not necessarily have the second work port drilled and tapped but they often do since it is the valve spool that determines the usage and there are several different spools for various purposes which can be used in a particular valve body.
 
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Discussion Starter · #13 ·
You need a power beyond kit for the first valve set of the system after the pump, not a closed center plug for the second valve set of the system. Lose the Tee fittings so that the power beyond port can be daisy chained directly to the supply side of the valve set in question and your issues will be solved.

Note that things like closed center plugs and power beyond kits are specific to the valve set in question and are not universal. From your description, the valve set on your tractor does not appear to already have a power beyond kit installed and you will need to go either to the Kubota dealer or a hydraulics shop (with the make and model number) to get one to install yourself. The Tee fittings are allowing alternative paths of least resistance through the open center of the tractor's valve set or the open center of the auxiliary valve set at any time that the other valve is selected.

Correct the plumbing as indicated above.

From the first pic that you posted, it appears that the added valve set is used to control a one way cylinder, and is plumbed incorrectly for even that task. The supply line connects to the unused quick connect and the ports in line with the valve handle are for the cylinder port(s). As plumbed, it won't work for 2-way cylinders. Valve sets made for one way cylinders do not necessarily have the second work port drilled and tapped but they often do since it is the valve spool that determines the usage and there are several different spools for various purposes which can be used in a particular valve body.
So when you say the supply line do you mean the pump side? Would it be possible to take my photo and label on it where I went wrong? The remote is for a haybine with only one hydraulic line that is gravity returned. I’m just learning about all this so pls be patient as I don’t know the terminology

and how does the power beyond kit work? Is it replacing the tee, or is it separate from it? Is it just it’s own valve that sort of allows power to be split off to 2 different applications?

also, I get that the way I’m going with isn’t ideal, I just don’t get why it wouldn’t physically work. When I disconnected the pump side that goes to the bucket after the tee, I have full power to the remotes I installed but the only problem is the gravity return haybine drops immediately when not lifting, which I thought is because it’s open center ( or is the quick connect in the wrong hole on the valve?). The idea was to have the system a bit janky, as in put a solenoid valve inline after the pump side tee to effectively do the same thing as disconnecting it, so that would give me power to the remotes. What I don’t get is what you guys are saying about having the remotes I installed closed center, please explain how that wouldn’t effectively make it like it was before, as in the fluid just normally flows through the open center on the original valve until needed to move the bucket.
 

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Discussion Starter · #14 ·
The Tee fittings are allowing alternative paths of least resistance through the open center of the tractor's valve set or the open center of the auxiliary valve set at any time that the other valve is selected
I get this part, it’s what I was trying to explain myself earlier. That’s why I’m wondering, obviously I can’t have 2 open centers in the system, so why can’t I have one open center and one closed center with a shutoff button on the open center to give full power to the closed center
 

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Closed center & open center valves aren't designed to be attached to same hyd system PERIOD. You need to forget about attempting to install closed center valve on open center hyd system. You can have multiple open center valves attached IN SERIES NOT TEED INTO SYSTEM to an open center hyd system. Closed center valve attached on open center system can cause hyd pump to FAIL
 

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Discussion Starter · #16 ·
Closed center & open center valves aren't designed to be attached to same hyd system PERIOD. You need to forget about attempting to install closed center valve on open center hyd system. You can have multiple open center valves attached IN SERIES NOT TEED INTO SYSTEM to an open center hyd system. Closed center valve attached on open center system can cause hyd pump to FAIL
So am I understanding correctly that you’re saying I need to get a hydraulic place to make a custom valve block that has a power beyond kit to replace the original valve? And then run from that to my remotes?
 

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Discussion Starter · #18 ·
Ok I need someone to explain to me how it’s gonna wreck the hydraulic pump if the fluid always has somewhere to go…like you guys are explaining to me stuff I already made clear I knew in previous posts, but seemingly can’t give me an explanation beyond “it’ll wreck the pump”. Is it gonna wreck the pump because it’s preventing constant flow? Because I set it up that it will have a path to flow when not used, ie through the original open center valve
 

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Closed center valve when spool is in neutral blocks the flow of oil. Then when CC center valve spool is in neutral hyd pump flow has no avenue to return to tank so pump housing could or possibly will fail. Attaching hyd valve to tractor hyd system incorrectly & correctly are 2 totally different things.
 

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To expand a bit on what Jim is saying, if you make that valve set closed center, what do you suppose happens when the cylinders hit end of stroke where there is no path back to the reservoir for the fluid being pumped? It goes over the relief valve just like normal, as long as there is a power beyond kit plus a return line in the first valve set of the series. Oops, with no power beyond kit and the return line is being used to supply the second valve set, then there is no direct path for the relief valve to dump fluid into the reservoir, so the fixed displacement pump tries to cram an incompressible fluid into a dead ended system with every rotation and something is going to give. That is usually the rather expensive pump case.

Who said anything about a custom valve block? Power beyond kits, or plugs if you prefer, are usually available for those relatively modern valve sets that are made for that option, and a hydraulic shop can tell you if one is available for your tractor's valve body and order it for you.

Your system is currently not plumbed correctly. Sort out the plumbing as has been suggested, and it will work correctly.

> - Denotes hose.

Pump > Tractor's valve set Power beyond port > New valve set > Return to tank.
....................... " ........... " ..." ..... Return port > Relieved fluid return to tank

Sorry. Try as much as I can, I just can't make it any simpler.
 
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