Powering low flow motor from Kubota L3600 hydraulics

[JimS]

I am looking at driving a motor for a sickle bar that is rated at 4 gpm from my L3600. Rated flow for the tractor is 8 GPM. I have a Kubota loader and 1 factory valve in the back for 3 pt. tilt.

Basically have two questions:

How do I tap into the hydraulics to run the valves for lift cylinder and motor? I could remove the loader and use those ports but I leave the loader on all the time and another solution would be good. Would like to have quick disconnects on the added unit as it will be mounted only when being used.

I could use the quick disconnects from the tilt valve and make something to hold the valve open. The connections are near the point of use on the 3 point hitch.
Seems better to break the pressure return line (PB) from the loader valve (at the quick disconnect) and run that to the sickle bar valves. The return from the added valves would go to the other side of that quick disconnect. Then I need to hook the motor drain line somewhere. I think I could dump that into the 3rd line from the loader valve. Does that sound right?

How do I reduce the flow? Since power needed is low how well would just running at half engine speed work?

Is this a suitable flow regulator? http://www.northerntool.com/shop/tools/product_200339421_200339421

 

[J_J]

Your ideal situation would be to get a stacked valve for the remote with one spool for cyl and another spool for motor control.

The motor spool would let you provide a certain GPM for the motor.

You probably have a hyd block in the middle bottom.

The FEL valve PB would feed the remote valve.

The valve should have PB so it can be feed the 3pt.

Best option.

Could also use a flow control valve to provide 4 GPM CF/control flow to the sickle bar motor.

3/8 NPT HYD FLOW CONTROL VALVE W/RELIEF RDRS137-08

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Your motor drain can go to any return line or to filler cap.

Does your sickle bar mower have valves now? IF so, the flow control would provide the sickle bar valve with 4 GPM and the EF/excess flow flow would go to the 3pt.

Your FEL PB probably feeds the hyd blk, so you would remove the hyd blk line going to the 3pt, and connect it to the new control flow valve IN port.

4 GPM CF goes to sickle bar mower and 4 GPM EF goes to 3pt.

 

[JimS]

Mower already has valves. If I hook the 4 GPM CF to mower and 4 GPM EF to 3 pt. then 3 pt will only get the excess above 4 GPM. Seems like it would be better to run the output of the mower (PB port) to the 3 pt. That way if I am running at 3/4 trottle and only have 6 GPM available then I will have 4 GPM to 3 pt. (rather than 2 if hooked to EF port). Not worried about speed of 3pt. but if hooked to EF port and at low throttle I may not have 4 GPM total available and none will go to 3 pt. Or am I thinking of this wrong?

With the constant flow valve I have an extra line. Can I hook the EF line to the tank return along with the motor return line loader valve return line? That will probably put more flow in that line than it was intended for.

 

[J_J]

You can switch the flow any way you want.

How much speed do you need on the 3pt. GPM's determine the speed of operation.

You can connect all the return lines as the total flow is still the pumps 8 GPM. If you have to, you can upsize the return hose at the junction for all the hoses.

You can control motor speed by the engine rpm.

 

[JimS]

Maybe I am not using the proper terms for things. One of my concerns is what to do with the motor vent line. This is intended to return to the tank and (I think) can't tolerate much back pressure so may not want to be combined with other returns. The unit comes with a tapered rubber "cork" that is intended to go in the fill hole of the tank. That may be the best way to handle that although I will try to at least make a retainer of some sort so the line can't fall out of the fill hole.

I have always been confused by the 3 lines from the loader valve. In, out (returns to tank) and PB (which goes to 3pt). I guess the 'out' port is only needed for the float function so the cylinders can dump any fluid back to the tank without any back pressure? If that's the case is there any issue with hooking the motor vent line to the out line? When using the mower the 'out' line back to the tank will also have the EF flow from the flow regulator so may have a small amount pressure.

For the flow control valve you posted I think the EF port must not have restriction and be returned to the tank. Some other valves apparently allow pressure here such that the EF port could be combined with the output of the mower to get full flow to the 3 pt. In any case the speed of the 3 pt. is not a big issue so I am thinking:

PB from loader to input of flow control valve
Out from flow control to mower valves
Out (PB) from mower valves to 3 pt (where PB from loader previously attached)
EF from flow control to Out line of loader (return to tank - requires tee)
Mower motor vent line to fill hole of tank

 

[J_J]

Does your sickle bar mower have PB ports?

If so, you have everything you need to power the 3pt.

The hyd motor drain line should go to tank which every way you can do it.

It can go direct or go into a tee with a larger hose going to tank to help reduce back pressure. .

If you are curious about the back pressure, install a gage in the tank line and check on it.

 

[NoSoMo]

Flow is also determined by engine RPM. Do you need to run at full RPMs? Seems more beneficial to run at lower RPMs if that gives you the needed flow. Saves on Fuel.