How do i size a Aux loader valve? Putting it in series.

[rScotty]

Heres the valve I think I will use.

Prince MB21BB5C1 Directional Control Valve, Monoblock, Cast Iron, 2 Spool, 4 Ways, 3 Positions, Double Acting Cylinder Spool, Spring Center, Straight Handle, 35 psi, 8 gpm, In/Out: #8 SAE, Work #8 SAE: Hydraulic Directional Control Valves: Amazon.com: Industrial & Scientific

Looks good. I see that others also have the same popular small tractor loader valve. Here is one similar or maybe even the same that comes with a PBY plug and has a dimensional diagram online so you can see how it will fit up.
2 Spool 8 GPM Prince MB21BB5C1 DA Valve | Directional Control Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com
rScotty

 

[ericm979]

The maximum tank port pressure on that valve is 500psi per Prince specs for MB valves. When you lift something significant on the 3pt you will exceed that. That can damage the valve or worse. You need to use the power beyond port to feed the 3pt.

 

[Burns331]

The maximum tank port pressure on that valve is 500psi per Prince specs for MB valves. When you lift something significant on the 3pt you will exceed that. That can damage the valve or worse. You need to use the power beyond port to feed the 3pt.

What does the 3pt have to do with this loop? The tank port line is the one going back to the tank right? Im planning on tie that into the drain for the hydro.

 

[aczlan]

What does the 3pt have to do with this loop? The tank port line is the one going back to the tank right? Im planning on tie that into the drain for the hydro.

The flow goes from the pump, to your loader valve, to your new valve, then to the 3 point hitch valve.
when you lift the 3 point hitch valve and pressurizes everything upstream all the way back up to the pump. As such if it takes 2000 PSI to lift the attachment on the three-point then everything up to the pump has to be able to handle 2000 PSI.
That is where the Open Center Power Beyond is useful because the tank Port does not get pressurized, just the inlet and power beyond ports.

Aaron Z

 

[rScotty]

The flow goes from the pump, to your loader valve, to your new valve, then to the 3 point hitch valve.
when you lift the 3 point hitch valve and pressurizes everything upstream all the way back up to the pump. As such if it takes 2000 PSI to lift the attachment on the three-point then everything up to the pump has to be able to handle 2000 PSI.
That is where the Open Center Power Beyond is useful because the tank Port does not get pressurized, just the inlet and power beyond ports.
Aaron Z

Aaron, which way are we running the plumbing here? Are you and the the OP saying different things?
Back in post #1, the OP wrote, "I want to add a 2 lever aux valve to my EX3200 Yanmar. I know the routing of the system. I will be interrupting the circuit going from the pump to the loader valve."

If he does it that way, I think he will need for the new 2 lever aux valve to have a PBY port to feed the next valve in the series - which he intends to be the original loader valve. I don't see why that wouldn't work. The new valve simply interrupts the flow to the existing loader valve and will add an additional 2 functions.Of couse, the new valve will also need its own return to tank line to service fluid returning when he uses those 2 new functions.

As I see it, the rest of the system including the 3pt hitch will work just as everything did before. The only downside to how the OP wants to plumb the system is that his loader will either not work or will work very slowly whenever he is using one of the new valve's additional 2 functions. But while he is not using the additional functions all should be as before....maybe a little slower due to the slightly reduced flow from friction, but no major difference.

I do not see why plumbing an open center system in the way explained above should add any addional pressure from the 3pt lift.
I do agree that it is critical that the new valve have a PBY port with the proper PBY sleeve in it so that he can feed the old loader valve.
And of course the additional return to the tank line that I mentioned.

What am I missing here?
rScotty

 

[ptsg]

So im just going to skip putting PYB on. Im just going to go inline from the pump out to the new aux valve and then to the rock valve like the OEM. Which brings me back to what sizing. I think my OEM pump on my tractor is 5.6 GPM. So do i just get a dual stick that flows that much?

What am I missing here?
rScotty

This is the post #28. Then he said the tank line would go right to to the tank, which is right, but skipping the PB means he won't have loader, remotes or 3pt. That's why Aaron explained the need for the PB.

 

[aczlan]

This is the post #28. Then he said the tank line would go right to to the tank, which is right, but skipping the PB means he won't have loader, remotes or 3pt. That's why Aaron explained the need for the PB.

Exactly, I mixed up the order of the loader valve and the new valve.
The valve in question has a limit of 500 PSI unless you're using it as a power beyond valve.
As such, if the OP does not use power beyond, when they go to lift the loader or the three-point they have a good chance of exploding the new valve.

Aaron Z

 

[rScotty]

Exactly, I mixed up the order of the loader valve and the new valve.
The valve in question has a limit of 500 PSI unless you're using it as a power beyond valve.
As such, if the OP does not use power beyond, when they go to lift the loader or the three-point they have a good chance of exploding the new valve.
Aaron Z

OK, thanks to Aaron and ptsg for straightening this out. In think that because in my own posts I kept saying that an active PBY port is a necessity, I simply assumed that the OP was going to plumb that way - and maybe he is. Luckily the Prince MB21BB5C1 valve he has chosen normally comes with a PBY port and the optional sleeve. So he should be OK.

And as a lesson to myself, I think it's a good time to learn how to post hand-drawn sketches here on TBN.
rScotty

 

[electrycmonk]

Question folks. I'm not want to hyjack thread, mearly point out a similar unit with similar price and more options.
https://www.amazon.com/dp/B013WYP1P...olid=22IIJHGGP1VTE&psc=1&ref_=lv_ov_lig_dp_it

As both of our CUT have about the same GPM flow, wouldn't this be an equal option for him as well? Given that it also has extra ports for future add-ons? IT also allows for PBY or switching to a "Closed" system as they advertise it as default "Open" system.

Or is this a bad idea for him overall?

 

[ericm979]

It's common to be able to switch a valve between closed and open system use. But you can't run a closed valve on an open system. Pretty much all modern CUTS are open system. It's cheaper and works well enough.

If you're already making mounts and running hoses you might as well get a valve that has more spools than you think you need now.

If you are not using the PB port and are running all the valve's output out the tank port, you need a valve whose tank port is rated for full system pressure. Because no matter where you put it in the chain there will be at least one valve (the 3pt) after it. When you raise the 3pt ALL the valves in the system see that pressure on their in and PB or tank ports.