Just Discovered that Pump Out and Power Beyond hoses to Loader Reversed at Block ???

Gordon Gould · Nov 27, 2020

3 years ago I bought a used Kubota M5640 with 700 hrs on it. Since then I have added another 450 hrs. It has a L1002 Loader, a (WR Long ?) 3rd function valve, and a single Rear Remote. All part of the original package according to the seller. I am planning on adding some hydraulics and was out tracing the hoses to see what what was what. In the process I discovered the PO and PB hoses are reversed on the hydraulic block. Brings lots of questions to my mind to say the least. But I have had no problems at all. I need some input or advise from someone with more knowledge than me.

This is the way it is plumbed following the fluid flow path. Pump Out from the block goes to the Out port on the 3rd function valve. Power In on 3rd func goes to Loader valve Power Beyond. Power In on Loader valve goes back to the Power Beyond on the hydraulic block. So the flow thru the valves is reversed from what it should be. The Tank port on the Loader valve is OK. Is this plumbing OK ?? If not why is all good after over 1000 hrs. Should I switch the block lines. Has any unseen damage occurred ?? Thanks.

gg

ptsg · Nov 27, 2020

Would have to see an hydraulic diagram for that tractor to be 100% sure, but I think what saved you, is that most manufacturers will put a safety relief valve right at the hydraulic block on the flow path straight from the pump. Otherwise, once you used the third function valve, it would dead end the circuit and most likely crack the hydraulic pump or shear the shaft of the pump.

Gordon Gould · Nov 27, 2020

OK Thanks - if I understand, this is what you are saying - because the 3rd function valve is first the pressure relief in the loader valve does not fire and the relief pressure is controlled by the pump relief valve. Another question - if there was no loader valve, as it is an option, would the pump pressure relief valve be used to protect the system or are there other relief valves in the 3ph or rear remotes ??
In other words is it bad relying on the pump relief valve like I am now ??

gg

ptsg · Nov 27, 2020

So most systems are setup like this: Pump -> Hydraulic block -> loader valve -> 3rd function (if fitted) -> remotes > 3pt valve. Some tractors may vary, so don't take it 100% for granted.

The hydraulic block, loader valve, remote valve, 3pt valve will have a safety relief valve. Basically one per component. The 3rd function, depending on what valve they used, may or may not have a relief valve. Usually the solenoid operated 3rd function valves, don't have a relief valves.

The 3 pt system actually have two relief valves. One for the valve that limits the max pressure and another one connected directly to the cylinders, so if you hit a bump hard with a heavy implement in the back, the relief valve gives before something breaks.

It's always a good thing having all the relief valves able to work, in case one or another get stuck or something weird happens.

One way or another, I believe I answer your questions. Hopefully I wrote that in an understandable way.

I would fix your system. Put the loader valve first, then 3rd function, and the rest is already good to go.

Gordon Gould · Nov 27, 2020

Thank you for taking the time for a teaching session ptsg. That was a very clear and helpful explanation. And I will be changing it around like it should be.

gg

Gordon Gould · Nov 28, 2020

Thinking about this and trying to get it all straight in my head how hydraulic valves work I have another question - If the flow thru the Loader valve is reversed does that put the loader valve relief down stream of the work ports so that the loader components are not protected by it ?? If so their relief would come from the pump relief valve also. Or does the Loader relief valve see pressure any where in the valve body so it would still be protecting the loader components ??

gg

Rustyiron · Nov 28, 2020

Gordon I wonder (if I understand your description properly) that if you're 3rd function is fed first, and reversed, if it's as simple as your control buttons are reversed in their operation?

Gordon Gould · Nov 28, 2020

That's the thing - nothing is obviously wrong. Every thing seems to works as it should. I'm just wondering out loud here about what might actually be happening to make it seem like nothing is wrong. If the weather co-operates tomorrow I am going to take some pressure measurements and then change the plumbing around to the way it should be and see what changes.

gg

ptsg · Nov 28, 2020

If you could find a workshop manual with the hydraulic diagrams would be awesome to make sure of the order of the components.

Dave M7040 · Nov 28, 2020

What are you calling a hydraulic block? I do not see one listed on parts illustrations.

It is easy to get confused when hydraulic components are connected together.

One valve's IN is fed by another component's OUT.

I have been told by Cross Manufacturing's tech specialist if that if the P (Pump out) and PB hoses are swapped the valve will not operate properly.

No, it will not operate properly. When the spool is shifted the Power Byd is blocked.

Thanks, Jeff

I doubt you have circuits improperly connected. Only change them after great study. In hydraulics, expensive components are destroyed in fractions of a second. It is not a "Lets try and see what happens," world.

Dave M7040

WranglerX · Nov 28, 2020

In a open valve, series system its always after pump and first valve body "power in" (P), its usually then from "power beyond" (PB) port to next valve body "power in" (P) port and so on through each successive valve body till it gets to 3PH which is usually last hydraulic mechanism in system... At least this my understand of general hydraulics...

Dale

Gordon Gould · Nov 29, 2020

Dave M7040 said:
What are you calling a hydraulic block? I do not see one listed on parts illustrations.

It is easy to get confused when hydraulic components are connected together.

One valve's IN is fed by another component's OUT.

I have been told by Cross Manufacturing's tech specialist if that if the P (Pump out) and PB hoses are swapped the valve will not operate properly.

No, it will not operate properly. When the spool is shifted the Power Byd is blocked.

Thanks, Jeff

I doubt you have circuits improperly connected. Only change them after great study. In hydraulics, expensive components are destroyed in fractions of a second. It is not a "Lets try and see what happens," world.

Dave M7040

Thanks for the warning Dave. I looked at this long and hard before I came to the conclusion it was incorrect. I'm no expert but know the basics and have done several Hydraulic mods on tractors and dozers. I have a tractor op manual which shows and explains the hydraulic block and valve position when a loader is added and I have the loader installation manual. Both agree in illustrations and wording that the lines are swapped at the block.

Your statement about the blocked PB port just adds to the mystery. I am not going to do any thing I can't undo and I understand the potential for damage.

gg

K5lwq · Nov 29, 2020

Gordon, could you take some pictures of what you are seeing? I am not understanding how it has been fine reversed all this time.

Gordon Gould · Nov 29, 2020

If I am wrong now is the time for me to find out ! So I appreciate all the help.

OK here is a 2 minute video tracing the flow direction from pump out on the block to PB return to the block. I think it is reversed. Then there is the loader operating.

M5640 Hydraulics Reversed - YouTube

Here are some pics. Hydraulic Block - Green is pump out

3rd Function valve - Green into Power Out

In front line goes from Power in marked P on 3rd Func to Loader Valve PB out

Yellow on Loader valve is Power In and goes back to The hydraulic block Power Beyond in (see pic 1)

A couple from the two manuals

So what do you think ?????

gg

ptsg · Nov 29, 2020

Great video describing all the routing Gordon. Along with the pictures, it helped tremendously figuring this out.

From your description and following the hoses, it does indeed look like the green and yellow are swapped. The good thing is that the loader valve is hooked properly, it's just not on the right order. Should be loader valve then 3rd function.

The green line should go on the In port of the loader valve. The PB line from the loader valve will feed the P port of the 3rd function. The T/Out port of the 3rd function will go back to the PB port of the hydraulic block.

Regarding the functionality of the system. I don't think you won't notice anything after the changes but the system will be better protected this way. If anything, the 3rd function won't get flow until you have the loader valve lever in Neutral.

On a side note, the Tank hose on the loader valve (4rd picture) is rubbing very hard on the mount. You may want to loosen the 45 degree fitting and rotate the hose slightly so the mount doesn't cut the hose open.

Gordon Gould · Nov 29, 2020

Well I solved the mystery. It turned out to be the only thing that would make all the info and knowledge from you guys correct and me looking foolish.

I took off my small belly pan and cut all the tie wraps securing the hoses inside their sheath to the tractor bottom. I removed the Green hose from the hydraulic block then loosened the green hose at the 3rd func valve so I could rotate 180 for it's new connection point on the block. It wouldn't rotate. Started pulling on hoses. What the flip - The Green hose has Yellow tape on the other end and the Yellow has Green. The joke is on me. All I need to do is swap the tape on one end.

Thanks for the support and sorry to be a bother. In hind sight I should have taken the bottom off first and removed a hose end so I would be sure.

gg

K5lwq · Nov 29, 2020

Lol now it is making more sense. Don't feel bad, we all have done something like that before. :thumbsup:

Gordon Gould · Nov 29, 2020

Thanks ptsg, good eye on the tank hose. It had a pretty good notch started from that corner. Moved it away. So I gained something in this exercise.

gg