Tapping off Hydraulic line for thumb

[racerboy832]

Without getting all technical can someone tell me if this is feasible. Kelly B30 Backhoe with it's own pump. I was thinking I would T the main pressure line coming into the stock lever body. Off the T I would run hydraulic line to a wood splitter type valve and connect it to the thumb cylinder, Then return line would get taped into the return line after lever body block. There are 3/8 lines running from the pump to the backhoe valve body. I was only planning on using 1/4 for the thumb. I'm sure I could go electric but I want it all self contained. I'm sure I could add a lever to the block but I don't want to split it open.

 

[KubotaSam]

Putting a T in the line will not work. All the hydraulic pressure will pass through the valve you are not using at any given moment and you will not have any force on the cylinder. Ex. If you are trying to operate the thumb all the oil will pass through the Hoe controlls. If you are trying to operate the hoe all the pressure will pass through the thumb controll. You need to hook a power beyond valve in series with the line from the pump to the hoe control.

 

[racerboy832]

I'm getting myself confused already. All I can tell so far. I have Power from the pump line going into the block with the 4 levers on it and then a return line back to the tank. There is a pressure gauge. I don't see any room to add another lever to the mix on the block. Where can I tap off the block for this PB thingy?

 

[countrybumpkin]

you can also use a diverter valve on one of the outriggers and select between the two. flip it one way and use the outrigger, then flip it the other and the lever for the outrigger then operates the thumb.

 

[mrmikey]

Where can I tap off the block for this PB thingy?

It replaces the outlet in a valve to allow you to get hydraulic pressure downstream to another valve without putting pressure on the return side of the first valve. It's usually called a power beyond plug.
What you'll end up with is two hydraulic valves plumbed in series, pressure in>1ST VALVE out>in 2ND VALVE>out to tank....Mike

 

[J_J]

If your valve has only 6 hoses, it does not have PB, or the PB outlet is not being used. . How about some pictures of the top and both sides.

 

[dfkrug]

I don't see any room to add another lever to the mix on the block. Where can I tap off the block for this PB thingy?

You are not going to tap into the existing valve stack to power the thumb.
It does not have Power Beyond.

That means you will have to buy a 1-spool valve with PB, and connect
it in series BEFORE the stack valve. That means pump Out goes to Thumb
valve In, and Thumb Valve PB goes to stack valve In. Thumb valve
Out (aka T) can be Teed into the stack valve Out. You will have to find
a suitable place to mount the valve.

Note: you have to get technical to do this right.

 

[kennyd]

You are not going to tap into the existing valve stack to power the thumb.
It does not have Power Beyond.

That means you will have to buy a 1-spool valve with PB, and connect
it in series BEFORE the stack valve. That means pump Out goes to Thumb
valve In, and Thumb Valve PB goes to stack valve In. Thumb valve
Out (aka T) can be Teed into the stack valve Out. You will have to find
a suitable place to mount the valve.

Note: you have to get technical to do this right.

Exactly correct.

 

[J_J]

Using a single valve before main valve could cause some problems, and that being when you use all the hyd flow through the valve to control the thumb, you can not use the other functions. You could perhaps use some of the fluid for the thumb, and the rest would be available for the other valve. Is that a problem, maybe not, it would depend on how you use the machine. There are also other ways, to split the flow, with part of the flow going to the thumb, and the rest going to the main valve. This splitter valve is not cheap though, but neither is the other valve with PB. This splitter valve also has a relief set at 1500 psi, and this would prevent the thumb from over powering the bucket cyl. . Just something to think about.

You would connect the thumb circuit to the 1.5 GPM port.

https://www.surpluscenter.com/item.asp?item=9-4158-15&catname=hydraulic

https://www.surpluscenter.com/Instruct/I9-4158-15.pdf

 

[dfkrug]

Using a single valve before main valve could cause some problems, and that being when you use all the hyd flow through the valve to control the thumb, you can not use the other functions.

This is true of all the valves on most hoe attachments: the only way
to use more than one valve simultaneously is by feathering the control
levers. But usually only one valve is working at a time. This is a
limitation of a one-pump system, surely, but you don't generally see
flow dividers here.

A separate monoblock valve before the stack valves will not cause any
problems....it would be just like any other valve in the stack.