3Pt hydraulics question

[puckgrinder85]

We have a EX3200 with a backblade and an added on valve to control a bucket "thumb" i guess you could call it. There is a "out" hydraulic port near the 3pt hook up as well as a return. The "out" runs to the added on valve and obviously the return runs back through to the return line and port at the rear of the tractor. The problem we have is with this valve in here, lifting the 3 pt hitch basically moves the add on valve and much exhaust pressure, enough to where the 3 point wont lift at all. We can manually hold the lever for the add on valve in a certain spot to get the 3pt to move but obviously is a pain in the ***** and we cant be very precise with what we need to do. Is there any simple means of getting this under control? We do have a hydraulics guy in town but we have yet to get any time to consult. Would like an idea of whats involved however..

 

[beenthere]

Are you trying to operate the back blade on the 3 ph the same time as the thumb on the bucket?

A pic would be helpful, but from the description, I don't follow. :confused3:

 

[J_J]

If someone plumbed the open center valves correctly, and with the valves in neutral, the fluid should flow from pump, through all the valves to tank. The 3pt should work normally. All the valves should be in series. The last valve should be the 3pt.

 

[puckgrinder85]

Well the valve is centered but as soon as you apply any lever to lift the three point hitch the valve moves over and in turn operates the thumb unless i forcefully hold the valve centered, in which the three point wil then raise. Why it moves is beyond me. I'll try to get a picture if i can. One more thing to note is the add on valve has a lock which will kick out after the thumb completely closes. Probabyl not of importance but thought i'd mention it.

 

[Leejohn]

sounds like the hoses are crossed on one of the valves, and I would guess it's the one that the handle is moving.

 

[J_J]

I agree, check those hoses. Appears to be hooked up wrong.

 

[puckgrinder85]

Just before i look, the feed and return hoses are on the top and bottom of the valve assembly respectively and the lines that actually run to the "thumb" are on the side of the valve body which seems correct to me, but i'll look at it closer for any markings at all. I even disconnected teh thumbs' hydraulic lines after the valve and operating the 3pt still moves the valve. I wonder if the valve has some sort of pilot thats causing this movement (remember i said it will kick out automatically after it closes fully).

 

[J_J]

Actually, most valves have pressure and return on the side, and the work ports off the top.

Look on the valve for some lettering, like IN or P
T or PB. work port may have A , B .

 

[KubotaSam]

I had the exact same symptoms of a valve moving itself by the internal hydraulic pressure years ago when I added a hydraulic boom to the rear of a Terratrac bulldozer. I had used the "return" from the blade valve to the "in" of the new boom valve (the valves in series). When I would push the handle to the boom valve as soon as it started to pick up a load (devolope pressure) the blade valve would move itself from the internal pressure on the spool of the valve. As you say if I held the blade valve in its center position the boom would operate as intended. I solved the problem by changing the blade vale (the valve closest to the pump) to a power beyond valve. This power beyond valve is designed to handle the pressure of another hydraulic system beyond it.
I think you need to change you new valve to a power beyond type.

 

[J_J]

puckgrinder85,

How about some pictures of your valve top, sides, and bottom.