Flow control

[luscsmith]

I am going to install a flow control on my Kubota 7040 and I have a question.
How will I return my waste oil back to the sump?
Any ideas on making a return replacement for the filler cap?

Thanks, Scott

 

[kjung17]

Not sure I, fully, understand the question. A flow control valve is, generally, in-line on the work pressure port and needs no dedicated return. If a dedicated return is required, you could tee into an existing return line. The fill cap is, often, the location of the vent and should not be blocked.

 

[Localmotion]

As Kjung says, you shouldn't need a return from a flow control valve

What is it for?

If it is to control the flow rate to the link arms / loader then I can see that a return may be needed to avoid stess to the pump - in which case you should be able to T-into the main hydraulic feed line from the sump to the pump.

If yo are wanting to vary the flow to an implement, I'd suggest an inline control valve between the tractor spool outlet (where the implement connects to) and the implement - these don't normally require a return and are fitted to the implement hydraulic line. If you need to use the valve with more than one implement, make up a short "adaptor" which fits into the tractor spool outlet, with a quickfit for the different implements to then connect to (hope that makes sense)?!

Here is a photo of a typical flow valve suitable for an implement which requires no return line and is widely fitted to feeders, muckspreader etc etc...

Hope this helps a bit???

 

[luscsmith]

This is for a hydraulic motor and I will change the speed. When the motor is running slow the flow control will send the unused oil to the sump so that the pressure regulator will not be opened.

Thanks, Scott

 

[Andrewnewy]

Normally there is a pressure free flow return to the axle on most tractors this is just dictated by a blanking plug somewhere on the back of the rear axle so you would just plumb it to there. However on the kubotas this is usually hard to get to or non-existent so what we do is place a fitting into the fill port and go in there. This does make it a pain to fill with oil, but not really many other options.
The main thing you want to make sure of is it is a zero pressure return, this would be the same for the output side of the motor and the case drain. Any back pressure in the return line with motors just produces heat and will cook your pump in no time. Also make sure your return line is big, I.e if your main line is 3/8" the make the return 1/2" and so on if bigger.

 

[luscsmith]

So I should not return the oil from the motor to the remote?

Scott

 

[kjung17]

You might get by with going to the remote. This may also cause a small amount of back pressure, as Andrew pointed out. An unrestricted return to sump is best for a motor application.

 

[AKKAMAAN]

I think luscsmith is talking about a regular control valve, or an adjustable diverter valve....

 

[J_J]

You may need a motor spool valve, especially if you want to reverse the flow. It could be detent also.

This is what I have to control the flow for all my hyd motor attachments, and others use a solenoid valve for motor on/off.

https://www.surpluscenter.com/item.asp?item=9-064-50&catname=hydraulic

https://www.surpluscenter.com/adspecs/AS9-064-50.pdf

 

[oldnslo]

The OP is talking about a pressure compensated Priority flow control. These are three ported valves and by-pass the excess flow at what ever pressure your system is operating at. If you use the fill port you will aerate the oil since it will dumping above fluid level. (J.J. links show two of these)

Depending on the flow rate and style of motor you can possibly tee the return port of the motor and the by-pass port together and then run them through the QD on the tractors directional valve. Most Low Speed High Torque motors used on Ag have a high pressure shaft seal that will with stand back pressure of 200 - 300 PSI or more. I would check what your particular motors capability is.

Is this motor ever going to be reversed? If yes then you will have to make provisions for this. Some priority valves will allow reverse flow and some won't.

Roy

 

[luscsmith]

The flow control you linked to is the valve I am looking at. Can I run it off the remotes I currently have? Can I tee off the ports that operates my loader where there is pressure and return capabilities: I could run lines to the flow control and mount all of that permanent then install quick connects on the valve.

Thanks again, Scott

 

[J_J]

Look at this link again, toward the bottom, and it will show how to connect it.

https://www.surpluscenter.com/adspecs/AS9-064-50.pdf

 

[luscsmith]

I think I know how it is plumbed but where would be the best source for the oil pressure and the return?

Thanks. Scott

 

[J_J]

You could plug it into your remotes, or feed the input from the pump and use the excess for another valve down steam.

If you did get the fluid from the remotes, you will have to bungee the lever, and run the output of the hyd motor back to the reservoir.

 

[kjung17]

I knew JJ would show up and save the day.:thumbsup:

 

[luscsmith]

JJ, where would you tie into the pump? Could I tee into the loader lines for the pressure and return lines? If I returned to the sump via the fill plug would that aerate the fluid?

Thanks, Scott

 

[J_J]

You can not tee into pressure lines, only the return.

That valve could go before the loader valve, or after.

I believe I would use a motor spool valve, and the connections would be easier , and you would have reverse for the hyd motor.

It depends where you put the valve, as to how the rest of the hyd system will operate. If the source of the motor fluid is upstream, the hyd motor will use all or most of the hyd fluid, and the rest of the system will get none. If you add it after the loader valve, then the loader operation will decrease flow to the hyd motor when used. So it really depends on how important the hyd motor attachment is to the operation of the hyd system. .

One other thing, will the motor operate at max speed or do you have plans for varying the speed of the motor?

Does your loader have PB?

 

[luscsmith]

I will change speeds.
I was looking at the valve you referenced, is that a motor spool valve?

Scott

 

[J_J]

Scott,

This is an 8 GPM motor spool valve, with PB.

https://www.surpluscenter.com/item.asp?item=9-7860&catname=hydraulic

This is a 14 GPM motor spool valve.

https://www.surpluscenter.com/item.asp?item=9-7975&catname=hydraulic

This is a hyd speed control valve, which varies the flow by opening an orifice to limit flow. It has no reverse.

https://www.surpluscenter.com/item.asp?item=9-064-50&catname=hydraulic

 

[luscsmith]

JJ, what is the difference between a spool valve and a motor spool valve?
Do I need a motor spool valve and a flow control?
Where would be the best place to get and return the oil?

Scott