Tree spade hydraulic issues

[wes_k]

Hello,

I've got a bit of a problem with a tree spade, and am looking for help.

I've got a Vermeer TS-30 tree spade (tractor-mounted version) that I hook up to my Deere 4020. It's probably 50 or more years old.
The problem is that when I use it, the hydraulics on the tree spade act funny. I engage the hydraulic pump on the tractor, and then can use the tree spade with no issues. When I disengage the pump on the tractor, often the hydraulic valve levers on the tree spade start slowly moving on their own (causing the various spade functions to engage; the spades open, the tilt engages, etc.), AND I get a bunch of hydraulic fluid leaking from the valves and running everywhere. Obviously this is not ideal. This is not new behavior, it has always done this (I've just put up with the bad behavior, but I need to fix it).

I have recently discovered that the tree spade is set up for open-center hydraulics and my tractor is closed-center. There is a plug to convert from open-center to closed-center, but I don't have the plug, Vermeer doesn't sell it anymore, and the original hydraulic supplier ("Energy") hasn't made this valve block in 40 years. From what I can tell, the plugs made for this type of conversion aren't universal, so I can't make one from another hydraulic manufacturer work. Our local welding shop 3D printed a rubber plug for me to try, but when I used it today, it still had the bad behavior. I know the problem is with the tree spade, because the tractor hydraulics work fine on other implements.

My questions:
1) Is what I'm seeing (valve levers moving and leaking hydraulic fluid) consistent with running open center hydraulics on a closed-center tractor? Or is something else going on? If I fix that problem, will it be resolved, or am I chasing the wrong cause to my issue?
2) Long-shot... does anyone know where I can find the plug to convert this system to run on CC hydraulics?

Thanks in advance for the help!

 

[oldnslo]

How are you supplying oil to the valve bank on the tree spade?

Where is the oil leaking from on the tree spade valve? Between the valve sections, out ends around the spool, etc?

Do the levers all move the same direction? I.e. handle moves away from valve body pulling spool out of valve body.

 

[zrtext]

Hi. First thing I would try is reversing the oil flow through the valve body, if you are hooking to your rear tractor remote couplings. Either interchange the hoses in the couplers or just move your tractor hydralic lever the opposite direction. My backhoe acts dumb if i get the fluid flow in the direction .

 

[wes_k]

Thanks for the replies, and the questions about the hydraulic flow direction. To be honest, I've never given it a thought about if I had the hoses hooked up correctly or not. There is a single SCV hookup on this tractor; the right-hand outlet is hooked up to the valve bank inlet, and I always run it with the hydraulic control lever on the tractor console in the forward position... I've never thought to run it in reverse, or with the hoses swapped. I'm pretty sure that the cylinders always work in the direction that they're marked on the tree spade (when I push the lever in the direction of "spade down", it always moves down, so I've never questioned how I had it hooked up). I'll try running with the control lever in the down position... hopefully it's that easy of a fix... I'll check tomorrow or Monday.

Here is a diagram I found; based on the way I think the SCV outlets operate on the tractor (pressure vs return), I may have been running this backwards...


To answer "oldnslo's" other questions, there's a pan underneath the valves that keeps me from seeing where the oil is coming from, but it does look like it's coming from more than one (or all of them). I do think that the valve levers move all the same direction when they move on their own.

Thanks again for the help.

 

[oldnslo]

Wes,
What might be happening is back pressure from tank line is causing the valves to leak around the spools. On the end opposite lever connections is the centering spring assemblies and caps or covers over these assemblies. If the cap is not vented and leakage slowly fills that cover it could push the spool moving the handles. What I can’t answer is why this would happen if the valve on tractor supplying oil is in spring center / home position.

It has been 20 plus years since been around a 4020 so don’t remember if there is a return or tank connection that does not go through selective control valve. If there is a connection direct to tank I would suggest connecting the return - tank line from tree spade to that connection. Pressure can stay connected to tractor as is today.

 

[GrandpaSmurf825]

I would try zrtext's suggestion first. I have worked with a lot of valve stacks and they absolutely have a correct flow direction. Usually the inlet and outlet ports will have a P for pressure and a T for tank. Pressure on the return side will cause it to do odd things. Unless you have damaged seals or o-rings the leakage should stop if you correct this. This is going to be an issue even if the "closed center" conversion is going to work. A flow restriction would have the same effect on the valve but I don't think you have that.