Closed center valve availability

[UncleBuck1]

The loader valve on my Deere 4020 is showing its age and starting to leak at the pistons. The valve is probably 35-40 years old, so its ready for replacement.

Are there any 2-spool valves that are manufactured as closed center on the market? Maybe I'm not looking hard enough, but it seems that all of the available valves are open center designs that are "converted" to closed center by installing a CC plug.

Or am I creating a difference where none exists- is a "converted" closed center valve any less reliable than one that was built that way?

 

[RickB]

There is no downside to an open center valve that is converted to CC. Pretty likely the valve on your 4020 is a Gresen valve that has both OC and CC capabilities. If CC valves were more popular than OC, valves would be sold as CC valves that could be converted to OC.

 

[Tx Jim]

True CC spool valves have no built in relief valve as no relief valve is needed. I agree with Rick that number of tractors with OC hyd's far out number the tractors with CC hyd's. It's highly possible Uncle Bucks hyd valve is CC only as many were used back when 4020's were new. Valve in photo is a strictly CC valve from a JD 148 loader with no relief valve or orifice for CC plug.

 

[J_J]

A closed center valve is just that.

It is designed to hold the fluid until needed.

It does not matter if the valve was made for closed center or a valve that can be modified to closed center. They both do the same job.

If you don't want the relief on the valve , screw it down till closed or replace it with a plug that blocks the relief discharge path.

A replacement valve from some place like Surplus will also be less expensive. Just match up the GPM's.

 

[UncleBuck1]

Thanks for the info guys. My loader is a JD710 (originally for an industrial tractor) and the valve is CC only; replacing it with a regular open center valve with a converter plug will simplify my shopping and save some cash.

Flow rating isn't much of an issue as I currently run the loader off the remotes (7gpm, I think); at some point I do plan to re-route the lines and tap into the rockshaft circuit which operates at full system flow of 21gpm, but I will probably install a flow restrictor to tone it down.

 

[Tx Jim]

It does not matter if the valve was made for closed center or a valve that can be modified to closed center. They both do the same job.

J_J
I agree but the 1st convertible hyd valve I encountered back in the '70's or '80's took me several hours of diagnosing hyd problems on a CC system on a JD before I realized that the seal on the CC plug had blown causing the hyd pump to run out of oil and cavitate. That several hours of wasted diagnostics time was etched in my memory.

 

[Tx Jim]

I think); at some point I do plan to re-route the lines and tap into the rockshaft circuit which operates at full system flow of 21gpm, but I will probably install a flow restrictor to tone it down.

Here's you some photos for attaching a loader valve on a 4020

 

[UncleBuck1]

True CC spool valves have no built in relief valve as no relief valve is needed.

If you don't want the relief on the valve , screw it down till closed or replace it with a plug that blocks the relief discharge path.

As has probably become clear, hyraulics is not my thing....

I realize that the relief valve is not needed, but does it present any problems on a converted CC valve? In other words, do I plug it or just ignore it??

 

[J_J]

You can't ignore it as the CC pump has its own relief valve. You either plug the relief port or set the relief valve pressure above the pump relief.

You only need one relief valve in the CC system, unless you want work port relief valves.