FEL control valve flow rate

TimBuck2 · Mar 2, 2015

I have a Kubota L4310 with a 7.8 GPM hydraulic system.

I am considering replacing my 2 spool FEL valve with a 3 spool valve as I want to add a separate set of hydraulic lines for remote hydraulics on the FEL.

The selection of 3 spool valves in the 8 GPM range seems to be a limited.

There are a lot of 3 spool valves to choose from in the 25 GPM range.

Is using a valve with a much higher flow capacity a problem?

I am thinking I will I loose SPEED control over my boom and curl if I use a valve with maximum flow rates significantly greater than 7.8 GPM?

BTW I need a float dentent replacement kit for my Kubota / Husco control valve.

The little kit is $133.35 plus shipping.

Add $120 or more for a separate one spool control valve, fittings etc. and I am thinking a new 3 spool valve might be had for not much more than the dentent kit and new one spool.

Thanks,

Tim

pmsmechanic · Mar 2, 2015

I could be wrong but I believe that the gpm rating is the maximum flow that the hydraulic spool will handle without being overly restrictive. So with a 25 gpm valve you could run the combined flow from three of your L4310 hydraulic pumps.

Leejohn · Mar 2, 2015

The 7.8gpm is at wide open speed I think. Do you think your joy stick well work on another valve
If it was me I would rather have the 8gpm valve over the 25gpm, 25gpm valve are big.

J_J · Mar 2, 2015

This valve will replace your FEL valve.

2 SPOOL COMPACT 10 GPM JOYSTICK CONTROL VALVE

A diverter valve will give you that extra function.

TimBuck2 · Mar 3, 2015

My concern would be that with a ca. 25 gpm valve, the entire 7.8 gpm would be "dumped" to the cylinder with just a small movement of the valve (I guess about 1/3 of the throw distance). So, it would be hard to control piston speed

However, I believe my loader valve is a variant of HUSCO 9210 (my tag fell off so can't be sure). Those have a max flow rate rating of 20GPM, so I probably would not feel the difference.

Leejohn, my loader valve joystick is built into the bracket that holds the valve. I think I could have a 3 spool valve made up that would work with the joystick (e.g., a BRAND TS model valve). However, looking this morning I see that I would have to cut away some of the bracket the supports the joystick so that the lever for the 3rd spool is accessible inside the cab. Alternatively, I would have to cut the whole top of the bracket off an use a valve with it's own joystick (similar to that suggested by JJ).

In the end, I don't want to cut up the loader just to reduce the hydraulic plumbing by a bit, so I am going to use a separate one spool valve for the third function.

Thanks for the input gents.

Tim

J_J · Mar 3, 2015

That one spool valve will have to have a PB port.

It could be lever or solenoid.

But why not use a diverter valve, or a 3rd function.

This is what most people use. The valves cost about the same.

TimBuck2 · Mar 3, 2015

JJ I have explained before, the hydraulic lines on my FEL boom are essentially all steel tubing, so a diverter would need to be at the cab, and I would need to run additionial lines out to the "end" of the
FEL boom anyhow.

I am going to do that with an additional position control valve in the cab, and use a diverter on that new circuit to get a 4th function on the FEL.

TimBuck2 · Mar 3, 2015

JJ, with your advice in previous posts I relize the third valve will be plumbed to the PB port on the existing FEL valve, then the PB port on the new valve will be plumbed to the hydraulic block which feeds the 3pt and the rear remotes.

The OUT port for the new valve will need to be tee'd to the OUT port (return to tank line) from the existing FEL valve.

Thanks

J_J · Mar 4, 2015

That is true if you use a lever valve.

If you use a 3rd function valve, the OUT port will go back to the hyd block.

Can you show a picture of your loader cross bar where the hyd lines change to hose.

TimBuck2 · Mar 4, 2015

JJ, I will post a picture of the FEL plumbing tonight, or in the AM.

TimBuck2 · Mar 5, 2015

J_J, here is how my FEL is plumbed. Using existing fittings on the boom, I cold only tap into half of the curl circuit with a diverter valve (right or left) leaving the other half as part of the second function circuit.

The only place to do it would be up near the cab.

J_J · Mar 5, 2015

I know what I would do. I see several good places.

However it is not my tractor.

Maybe something like this.

http://www.tractorbynet.com/forums/...tl-loader-diverter-valve-fasse-finished-1-jpg

TimBuck2 · Mar 5, 2015

The best I can tell from that picture, seems that the steel lines to the dipper cylinders were disconnected, and replaced with hoses to and from the diverter?

I think my plan will involved about he same or less new plumbing, and have the advantage of adding two remote circuits to the FEL rather than one. I think I will stick to my plan (if I ever find the time).

Thanks for your interest and advice.

Tim

jasong123 · Mar 24, 2015

TimBuck2 said:
My concern would be that with a ca. 25 gpm valve, the entire 7.8 gpm would be "dumped" to the cylinder with just a small movement of the valve (I guess about 1/3 of the throw distance). So, it would be hard to control piston speed

However, I believe my loader valve is a variant of HUSCO 9210 (my tag fell off so can't be sure). Those have a max flow rate rating of 20GPM, so I probably would not feel the difference.

Leejohn, my loader valve joystick is built into the bracket that holds the valve. I think I could have a 3 spool valve made up that would work with the joystick (e.g., a BRAND TS model valve). However, looking this morning I see that I would have to cut away some of the bracket the supports the joystick so that the lever for the 3rd spool is accessible inside the cab. Alternatively, I would have to cut the whole top of the bracket off an use a valve with it's own joystick (similar to that suggested by JJ).

In the end, I don't want to cut up the loader just to reduce the hydraulic plumbing by a bit, so I am going to use a separate one spool valve for the third function.

Thanks for the input gents.

Tim

Tim,

it is actually the opposite away around, the flow down the open center of the valve is pinched off causing the system pressure to rise and overcome the load in your Workport (i.e. the load on your cylinders). With a small amount of flow going down the open center and a spool designed for a larger amount of flow you would have to stroke the spool further to generate enough pressure to overcome the load in the Workport. The HUSCO valve is rated for higher than the 8gpm but the spools are tuned to the lower flow rate.

Regards,
Jason

TimBuck2 · Mar 26, 2015

Jason, you have given me something to thing about, but it is too late for me to finish my thinking tonight.

I am getting that when you operate the valve, you are pinching the open center flow. Are you saying that the work port is always open, and that you just build more preassure to lift the load by pinching the open center flow?

It seems to me that when pinching the open center flow, you also must be opening flow to the work port you want, otherwise, the added preassure would want to go to both work ports (extend and retract in the case of a double acting cylinder set-up).

jasong123 · Mar 27, 2015

No, the WP are closed when the spool is in neutral but as you stroke the spool you close the open center, open the power Workport(WP) and open the other WP to tank. if you stroke the spool in the other direction the same happens to the center but the connection to power and the connection to tank are reversed. how all this happens, the timing and pressure gradient are the art of the hydraulic design engineer and can be the difference between a well tuned and nice feeling machine and something uncontrolable. HUSCO work closely with the OEM to make sure that the valves are tuned closely to the requirements of the machine.

Jason
(Director of AG Products - HUSCO)

J_J · Mar 27, 2015

My thinking is this, and to put it another way, a mismatch of the GPM flow of pump to valve will slow things down.

The open lands of the spool allow a certain amount of flow to go to the work ports, and the other part keeps flowing downstream.

What you have is two paths, work port and downstream.

To stop downstream flow, you have to fully stroke the spool, and then you shut off pump flow for any valve downstream for a short period.

No matter what the valves flow rate in GPM is, the full volume will only go to the work port when the lever is fully activated.

If you have a 25 GPM valve and your pump flow is say 8 GPM, then at half lever, I would say that 4 GPM would be going to the work port and 4 GPM going downstream.

You want the full 8 GPM to go to the work port, then fully stroke the spool and that will shut off the pump flow downstream.

If you had a flow meter, you could see the results of valve flow.

TimBuck2 · Mar 27, 2015

Thanks J_J and Jason for your the interest. I have owned my old Ford for 24 years, but never really needed to think about hydraulics until I acquired my Kubota a year ago, and started envisioning what I can do with the extra hydraulics. I think I am learning slowly but surely, and folks on this forum are a big help.

Now Jason, if you could have gotten me that handful of parts to rebuild my float detent for something south of $134.95 (plus shipping and handling), that would have been really appreciated!