Advice on Hydraulic Circuit

[cycle_gator]

Good evening folks:

I am in the process of improving the hydraulics on my Kubota L4310. I am adding some degree of independence front and back, as well as a four section rear remote to power T & T plus two auxiliaries. I also have a backhoe currently on the machine. Hyd pump is about 7.5 GPM @ 2000 psi.

Below is a very crude diagram that shows the current hydraulic system in two different configurations with and without the backhoe and then two alternatives for the improvement. Note that the word "diverter valve" on the diagram should be more correctly labled as a "selector valve," still trying to get my terminology straight. The diagram is schematic and does not show relative position on the tractor, or spacing. It is just to work out the flow, relative position and spacing will come next. I am about to buy parts, so I want to be sure I am not buying things needlessly or getting into it and discover I should have bought somthing different or additional.

The rear remote valve will be a 4 section Prince monobloc Wolverine series with 8 gpm capacity, double acting, spring to center and power beyond as an option. Nothing fancy, but should do the job. The selector valve would be a manual valve like a Parker 24 GPM valve, push pull actuation. one In port, two out ports.

Here is what I am trying to achieve:

1.) Be able to run the backhoe when the FEL is not attached
2.) Add rear remotes
3.) No need to interconnect the FEL PB with Tank return when BH is not installed
4.) Add hard line from pump to rear of tractor for less damage exposure, no need to thread flex hoses from back to front when I install backhoe, not to mention laying on the ground to connect the QC's under the machine and secure the flex hoses.

Here are what I see as the pros and cons of my alternatives (feel free to disagree)

Alt. 1
1.) Minimizes any additional flow loss to BH potentially caused by the RR valve.
2.) Cannot run BH and RR's at the same time. At some point I may want to use the RR valves to run something attached to the BH, like a hyd thumb or ??.

Alt.2
1.) Allows BH and RR's to operate at the same time (that is somewhat relative, I realize given the 7 GPM flow.) The BH will swing and boom at the same time when running free, but that is about it.
2.) Eliminates one selector valve and all the associated fittings etc., less chances for leaks, lower cost for install.

Obviously I am leaning to alternative 2. Here are some questions I have:

1.) If I have the FEL removed, QC's disconnected, is there a problem if there is no flow to the LP return port on the pump? I honestly still do not understand the difference between the LP return port and the "tank" port on the pump.
2.) Is selector valve 1 sufficient to prevent backflow from the FEL PB port, when the valve is feeding port 2, that is will it maintain the series flow or allow a "short-curcuit" to occur? Same issue different component, When the FEL is disconnected will the QC be strong enough to prevent leakage when the selector valve is in position 1? This would be the QC just below the tee, immediately after the selector valve. Or should I add a manuel ball valve there to ensure no leakage?
3.) What am I missing here? I think I am beginning to understand all this hydraulic stuff, but some of the concepts are taking longer to sink in than others.
4.) Any recommendations on QC's, AG type like Parker 4200 series, or flush face units? I will be buying ten sets of them.

That is it. Thanks in advance for your help.

By the way AKKMAAN, if you read this situation with Ebay purchased valve was resolved, seller took it back. Manufacturer was of unknown orgin.

 

[kennyd]

I don't have time to get into detail now BUT:

For what you want, you do not need a diverter/selector valve.

You just need to plumb your new 4-spool valve into the PowerBeyond (PB) line from the existing FEL valve. The new 4-spool valve should be PB equipped so you can add QD's (quick disconnects) so you can "plug" your backhoe inline when needed.

You are over-complicating this, there are PLENTY of post's about adding rear remotes if you search some.

 

[cycle_gator]

KennyD:

Thanks for taking some time to respond. In my own defense what you see in the diagrams and questions is the result of researching at least two years worth of threads in the hydraulics forum and the Kubota owners forum on adding rear remotes. If it was not for that I would not even know where to start. I am just looking for some confirmation of where I am headed. Yes, I do tend to over-think things, professional hazard. So a couple easy and short questions:

1.) If I do not use a selector valve, I assume I would use a jumper hose from between the FEL HP QC and the FEL PB QC (both on the tractor side) when the FEL is removed and I still want to use the rear remotes? Alternately, I suppose I could plumb in a cross over on the back sides of the QC's between the same two lines with a suitable ball valve?
2.) This question from the original post is where I am most uncertain, even after looking at all the RR threads: "If I have the FEL removed, QC's disconnected, is there a problem if there is no flow to the LP return port on the pump? I honestly still do not understand the difference between the LP return port and the "tank" port on the pump."

Thanks again for the gracious offering of your time.

 

[kennyd]

KennyD:

Thanks for taking some time to respond. In my own defense what you see in the diagrams and questions is the result of researching at least two years worth of threads in the hydraulics forum and the Kubota owners forum on adding rear remotes. If it was not for that I would not even know where to start. I am just looking for some confirmation of where I am headed. Yes, I do tend to over-think things, professional hazard. So a couple easy and short questions:

1.) If I do not use a selector valve, I assume I would use a jumper hose from between the FEL HP QC and the FEL PB QC (both on the tractor side) when the FEL is removed and I still want to use the rear remotes? Alternately, I suppose I could plumb in a cross over on the back sides of the QC's between the same two lines with a suitable ball valve?
2.) This question from the original post is where I am most uncertain, even after looking at all the RR threads: "If I have the FEL removed, QC's disconnected, is there a problem if there is no flow to the LP return port on the pump? I honestly still do not understand the difference between the LP return port and the "tank" port on the pump."

Thanks again for the gracious offering of your time.

1. I guess your valve is removed with the loader frame? Then yes, the two lines would need to be connected together. The flow of oil CANNOT be interrupted!

2.The pump draws it oil from the tank(sump), through a filter. The T (tank) port (what you call LP) of the valve just carries waste oil from the work ports(cylinders), the main flow continues through the valve to the PB(power beyond-BYD) port the will feed the 3PH. If I am reading your question correctly, there is no difference between the LP and T ports.

Clear as mud?

 

[wdchyd]

1. I guess your valve is removed with the loader frame? Then yes, the two lines would need to be connected together. The flow of oil CANNOT be interrupted

I'm scared of QC's or diverter valves just beyond the pump without an extra relief valve added in between to protect the pump just in case....BANG!!!!:shocked:

 

[J_J]

The output from the last valve has to go to tank. The pump needs a continuous loop to supply the hydraulics. A closed QD in the flow path will cause the FEL valve to go into relief. All cylinders output has to go to tank. You could Tee into lines going to tank.