Adding Valve to Closed Center Post Pounder

[cwbwi]

Hello All!
I'm working on a custom hydraulic shift on my Shaver post pounder. I would like to add an additional 2 valve bank to the existing 3 valve system to power some additional hydraulic rams. The current valve is closed center and powers 3 rams, the final ram on the pounder is one way, so the return line dumps to the tank on the tractor, not back to the SCV.

My question is how to plumb in the new valve into this system. Am I correct in assuming that I should tee off the line from the tractor SCV and tee the return line to the tank because this is closed center? The shaver dealer is telling me I can put an open center valve with power beyond before the closed center valve, that doesn't seem right to me. Attached is a picture of what I'm working with.

The post pounder is on a John Deere 2555 tractor (closed center, 23 gpm, 2320 psi). Also, am I correct in assuming that I should turn the relief valve pressure setting on both these valves all the way up since the tractor has its own relief valve?

I'm considering purchasing this valve, the handles can be positioned similar to the existing valve and the specs seem to fit. It comes with a closed center plug and is reasonable at $112. What are your thoughts?


Thank you for your help!

 

[ptsg]

Yes you can add the second valve with two ways to do it.

One is to get a closed center plug for the new valve, mount it on the port that would be the power beyond port on a open center system. Then you tee the pressure lines of both valves and also tee the two tank lines together.

The other way is like the dealer said. You get a power beyond adapter, and tee the pressure lines, then the tank lines. But the new valve with the power beyond needs to be placed before the shaver valve, so the closed center plug on the second valve can still be effective.

I wouldn't adjust the pressure relief valves on the valves yet. They usually come preset at around 2600 PSI, or at least the ones sold here are that way. As you said, the pressure on the tractor is 2320 PSI.

 

[RickB]

Do it the way you have outlined. Tee the supply and returns, use the valve you have selected and buy and use the closed center plug in the added valve.
I would not adjust the PRVs.

 

[Tx Jim]

Do it the way you have outlined. Tee the supply and returns, use the valve you have selected and buy and use the closed center plug in the added valve.
I would not adjust the PRVs.

I'll disagree with RickB because a closed center control valve utilized on a JD 2555 needs the PRV closed completely or at least set above 2320 psi or frt hyd pump will most likely cavitate. JD closed center hyd control valves utilized on that model tractors don't require a relief valve & definitely will not operate correctly with an open center valve attached to closed center hyd system

 

[RickB]

I'll disagree with RickB because a closed center control valve utilized on a JD 2555 needs the PRV closed completely or at least set above 2320 psi or frt hyd pump will most likely cavitate.

Once again you are correct, my friend.

 

[WranglerX]

I would follow dealers advice as he probably has had a ton more experience than any single contributor on page.... And the logic is correct....

Dale

 

[Tx Jim]

I would follow dealers advice as he probably has had a ton more experience than any single contributor on page.... And the logic is correct....

Dale

Dale
If Shaver dealer states to install an open center valve on a tractor with closed center hyd system such as a JD 2555 then the dealer needs to attend a hyd school as he's giving incorrect hyd information. No I'm not a dealer BUT I was employed at a JD dealership for over 21 yrs with 13 of those yrs I served as dealer service manager. Closed center hyd's will not function as designed with an open center valve installed!!

 

[RickB]

I would follow dealers advice as he probably has had a ton more experience than any single contributor on page.... And the logic is correct....

Dale

22 years of dealership experience here and I have been around Deere closed center systems and Shaver drivers since the 1970s.

Some dealers have a wholesale supplier with a catalog of short line stuff that is available for retail sale. This dealer may never have seen a Shaver driver in person or set one up. Theoretically an open center PB capable valve upstream of a CC valve will work, but it is a needlessly complex installation.

 

[Tx Jim]

RickB
Would you please explain how to connect an open center valve on a closed center hyd system so CC hyd pump won't cavitate.
Thanks,Jim

 

[aczlan]

RickB
Would you please explain how to connect an open center valve on a closed center hyd system so CC hyd pump won't cavitate.
Thanks,Jim

It would have to be a Open Center Power Beyond valve. Just a Open Center valve wouldn't work.
You would take the line off the pump running into inlet of the valve, run the Power Beyond line out a Closed Center valve, then run the tank line into the Tank circuit.
As was said, needlessly complicated and it would just be easier to put in a closed center conversion plug to plug the power beyond port.

Aaron Z

 

[RickB]

RickB
Would you please explain how to connect an open center valve on a closed center hyd system so CC hyd pump won't cavitate.
Thanks,Jim

Exactly as described in the OP. Accepting flow from the tractor and using the PB flow from the O C valve to power the original CC pounder valve. The CC valve would stop the flow through the OC valve except when any valve spool was stroked.

 

[Tx Jim]

Aaron & Rick
Thanks for your reply. I'm not from the "show me state" BUT I'D HAVE TO WITNESS THIS FEAT to believe CC hyd pump won't cavitate with an OC valve with or without PBY attached to it. I've witnessed CC hyd system hyd pump cavitate when CC plug blew seal which is similar to valve with PBY plug. I guess I can't see the forest for the trees but I've spent many,many diagnosing CC hyd failures.

 

[RickB]

Aaron & Rick
Thanks for your reply. I'm not from the "show me state" BUT I'D HAVE TO WITNESS THIS FEAT to believe CC hyd pump won't cavitate with an OC valve with or without PBY attached to it. I've witnessed CC hyd system hyd pump cavitate when CC plug blew seal which is similar to valve with PBY plug. I guess I can't see the forest for the trees but I've spent many,many diagnosing CC hyd failures.

The downstream closed center valve blocks the flow from the Power Beyond port of the open center valve. That makes it function exactly as if that same OC valve had a closed center plug installed. Not ideal, but it would be fully functional and not compromise the CC system.

 

[aczlan]

The downstream closed center valve blocks the flow from the Power Beyond port of the open center valve. That makes it function exactly as if that same OC valve had a closed center plug installed. Not ideal, but it would be fully functional and not compromise the CC system.

Here is a flow diagram:

A and B are work ports
T is low pressure return to tank
P is high pressure in from the pump
PB is high pressure Power Beyond

Aaron Z

 

[WranglerX]

Here is a flow diagram:

A and B are work ports
T is low pressure return to tank
P is high pressure in from the pump
PB is high pressure Power Beyond

Aaron Z

This is my understanding how it should work....

Dale

 

[Tx Jim]

Although I've never seen or heard of this method of attaching open center control valve to closed center hyd system I can envision that returning oil to ""ported hyd filter cover"" could help keep CC pump from caviatating BUT returning simply to TANK I'd have to see it operate correctly to believe it. Can someone explain how returning oil to tank via the posted schematic is any different than blowing seal on CC plug on FEL valve which will return oil to tank will cause frt pump to cavitate??

IMHO JD engineers failed to install a high enough GPM trans pump from the beginning then when an internal leak to sump occurs frt pump runs out of oil too fast.

Has anyone witnessed 1st hand the system outlined in schematic operating on a JD CC hyd system??
Thanks,Jim

 

[Tx Jim]

The downstream closed center valve blocks the flow from the Power Beyond port of the open center valve.

Please explain this part of schematic because I can't determine how a CC valve is blocking the OC valve. Plus I'm not buying into the return oil(green line) will be low pressure. I've never measured it but when one sends 2250 psi to return line I think it won't be low pressure in return line.

Another fallacy to that schematic not functioning on a JD closed center hyd system is the blue arrow(suction) because JD piston pumps are incapable of sucking oil & requires oil to be supplied to them via a charge pump. The blue suction might be fine IF large hyd reservoir was mounted above CC pump but it won't operate correctly with smaller reservoir because many JD tractors have a smaller reservoir & had hyd problems

 

[RickB]

It will work. The flow characteristics will not differ from the original CC valve only installation. The diagram is functionally accurate except the detail of the missing charge pump and does not account for the woefully inadequate charge pumps used by Deere for decades.
If we cannot make you believe or understand that is OK.

 

[Tx Jim]

It will work.
If we cannot make you believe or understand that is OK.

Rick
I'm just attempting to determine how it's designed to work. I'm still attempting to understand how CC valve can block oil to the added OC valve. I suppose from what you stated that you have actually seen this type of setup utilized on a JD CC hyd system.
Thanks,Jim

 

[ptsg]

Rick
I'm just attempting to determine how it's designed to work. I'm still attempting to understand how CC valve can block oil to the added OC valve. I suppose from what you stated that you have actually seen this type of setup utilized on a JD CC hyd system.
Thanks,Jim

First valve will have a PB plug feeding the second valve. The second valve will then have a Closed center plug, therefore making both valves closed center. The pressure side will be blocked no matter how many valves are behind the last one (fitted with a CC plug).