replacing 5 valve bank with a three valve and a 2 valve bank connected

quietrangr · Aug 7, 2015

Hello, folks.
I've been here lots of times, but have just joined. I have at least one bad spool on a Gresen valve bank, and probably more. The bad spool is the swing on a log loader, and has a nick in it. It drifts horribly. It's old, so want to replace it with a three and two valve banks hooked together. They are about one third the price of the sectional bank. The machine is a John Deere 440C log skidder converted to a forwarder. From all I can gather, it's a closed center system. I know I would need a power beyond from the first to second valve bank, but then I would probably also need a closed center plug. Where do I put that plug? The current bank has both the main feed inlet and outlet at one end, but the other banks have inlet and outlet on opposite ends. On an open center system, I think the inlet comes in, then goes out the power beyond, to the next valve bank, but I'm puzzled as to where the outlet back to the reservoir is for the closed system. I've never worked with closed center before. Is there any help for me?

J_J · Aug 7, 2015

Closed center system do not use the PB port.

All closed center valves are in parallel.

A closed center plug goes in the PB port, closing off pump flow through the valve until needed.

The OUT ports from all valves go to tank.

Tx Jim · Aug 7, 2015

Welcome to TBN
I'll 2nd that closed center hyd systems require power beyond to be blocked off & all out ports go to tank.

quietrangr · Aug 8, 2015

Thanks for the replies. I would put the main feed in from the pump to the inlet, then the out port from the first control valve (will have three levers), goes to the tank, and the PB is blocked with a closed center plug? The second valve bank will have its own separate feed in from the pump, and will not be fed from the power beyond of the first valve bank? The second valve bank will have outlet going separately to the tank, and PB plugged with a closed center plug like the first valve bank? I will check back in tonight. Thanks.

J_J · Aug 8, 2015

Yes, that is correct.

quietrangr · Aug 8, 2015

Ok, thanks guys. Now I have another question. The current sectional swing valve and the main lift valve have relief valves with 1000 stamped onto them. This seems low, especially for main lift, but I should probably stay with that setting. The valves I'm looking at buying have adjustable reliefs 1500 to 2500, I think. So I guess I will need a lower relief setting. I've seen the inline relief valves at Surplus Center, different types. What would be best to install, and do both work lines need a relief valve?

Tx Jim · Aug 9, 2015

My knowledge of industrial equipment is very limited but 1000 psi setting on a relief valve seems to low to me on a system that should build pressure to about 2400 psi. It would be interesting to see what the JD tech manual lists for correct relief valve setting.

quietrangr · Aug 9, 2015

The machine is a pole skidder converted to a forwarder, so the tech manual will not say the setting for the added log loader, a Barko 40. (Ison Equipment, a regional JD dealer converted a number of pole skidders to forwarders in the 1980s.) The loader parts book says "relief setting stamped on valve," so that doesn't help either. I maybe should call Barko and see if somebody knows anything about a loader that ancient, or hook up a pressure gauge.

J_J · Aug 9, 2015

quietrangr said:
Ok, thanks guys. Now I have another question. The current sectional swing valve and the main lift valve have relief valves with 1000 stamped onto them. This seems low, especially for main lift, but I should probably stay with that setting. The valves I'm looking at buying have adjustable reliefs 1500 to 2500, I think. So I guess I will need a lower relief setting. I've seen the inline relief valves at Surplus Center, different types. What would be best to install, and do both work lines need a relief valve?

That stamped valve number might be the pressure limitation for the mechanical configuration for the machine for safety reasons.

Who is the manufacturer of the valves and the model number. Perhaps we can look up and see if there are different relief .

I believe both work ports need a relief valve as you might have a load on raise or lower.

You really need the valve specs, as some valves come with non adjustable reliefs set to your specs when you order the valve. The company might offer adjustable relief for that valve.

If you ordered stack valves, you could get work port relief in the spool assembly.

My BH has about 10 relief valves. Main relief and work port reliefs.