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kubotaguy54
02-25-2017, 07:48 PM
Need help! I have a B2920 Kubota tractor with backhoe and manual thumb. I want to change it to a hydraulic thumb. I used a 1 spool log splitter valve and teed into the hydraulic lines going to the backhoe. I ran the other 2 ports on the wood splitter valve to the hydraulic cylinder that opens the thumb. Why won't this work? The backhoe won't work unless the control valve is pushed forward or backward and then the thumb still won't work.

Boostinjdm
02-25-2017, 08:12 PM
sounds like a closed center valve. That blocks all ports when in the center (neutral) position. You need an open center valve if you are going to tee into something like that. You didn't say where exactly you tied into the system. Was it before the control valves? Or in one of the work lines? If tied into one of the working lines like the boom or stick, then not only will you have to run two levers to make the thumb work, but what ever you tied into is going to move also.

duckman
02-25-2017, 09:44 PM
I also have a Kubota BX model and they state "DO NOT DISCONNECT BACK HOE HOSES WITH TRACTOR RUNNING" you can blow/rupture the pump, if you installed a close center valve you may have damaged the pump

kubotaguy54
02-25-2017, 10:17 PM
sounds like a closed center valve. That blocks all ports when in the center (neutral) position. You need an open center valve if you are going to tee into something like that. You didn't say where exactly you tied into the system. Was it before the control valves? Or in one of the work lines? If tied into one of the working lines like the boom or stick, then not only will you have to run two levers to make the thumb work, but what ever you tied into is going to move also.

Yes, I teed it in before it went back to the controls on the backhoe. As soon as it comes out of the tractor and got back to the controls on the backhoe.

true temper
02-25-2017, 11:03 PM
My guess is you have an open center valve, and you need to get a power beyond plug installed in it to make it work.

1-800miner
02-25-2017, 11:52 PM
My guess is you have an open center valve, and you need to get a power beyond plug installed in it to make it work.

I concur.

Black Forest
02-26-2017, 12:59 AM
Just think about the oil coming from the pump. It will take the easiest route of least resistance back to tank. So if the oil is just making a circuit back to tank and you have a tee going to your thumb control when you activate the valve for the thumb you are effectively just blocking the flow at the thumb no different than if you capped the Tee. The oil just flows through the straight part of the Tee and goes direct to tank.

Boostinjdm
02-26-2017, 02:57 AM
Nevermind, I can't seem to think this through at the moment.




ETA

A better way would be to look at the backhoe valve body. If it is a stacked type, add in another segment and everything will be like a factory job.

I'm not familiar with your specific equipment, but a power beyond option may be available as mentioned.

ETA2

Teed in may be the problem. The oil has to actually pass through the valve. Post pics. That will clear things up.

kubotaguy54
02-26-2017, 04:08 PM
:confused::confused:
Need help! I have a B2920 Kubota tractor with backhoe and manual thumb. I want to change it to a hydraulic thumb. I used a 1 spool log splitter valve and teed into the hydraulic lines going to the backhoe. I ran the other 2 ports on the wood splitter valve to the hydraulic cylinder that opens the thumb. Why won't this work? The backhoe won't work unless the control valve is pushed forward or backward and then the thumb still won't work.

O.K. Here are some pics of what I did. Hope you can tell something from these. Thanks for all the comments! Well, can't figure out how to get them from my computer picture files to here. Be patient with me, I'm new to this. Can't figure it out. Sorry!