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

[Burns331]

I wan 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. I know the claimed flow rate of the hydraulic pump. I dont want to create a restriction in the system from additional line loss.

Say my pump is a 5 gpm pump, Is it okay to do a loader valve that is rated at 10 gpm to be on the safe side, or is there a negative to that?

I plan on running from the pump, to the new loader valve, then pass through to the old loader valve.

Thank you,

 

[ericm979]

When the valve is too much larger than the flow, the ability to 'feather' the valve for partial flow to the work ports is reduced. The feather zone becomes only a small part of the valve's total motion, and the low flow end of the range is cut off. When it's way too large the feather zone is so small that it's basically just on and off.

The text books recommend a valve that's about 25% more flow than the system. An 8 gpm valve would be a little better than the 10 but if 10 is what you can find go with it as it's probably not a huge difference. A 16 gpm valve on a 3 gpm system does not work too well.

Make sure your new valve's tank port is rated for full system pressure, or use a power beyond port to run the existing loader valve and tee the new valve's tank port into the old one.

 

[ptsg]

According to tractordata, your tractor have 5.6 GPM for the main pump and 4.3 GPM for the steering pump.

So I would say anything from 8 to 10 GPM valve, should be just fine. Don't forget the Power beyond sleeve for your new valve. :thumbsup:

 

[RNeumann]

Couple of side notes as your questions were covered well by the post above.

QDs can be choke point that restrict flow- size those if you use any in your circuit.

A lot of loader valves have the pressure regulator/reducer in them. I don’t know if that’s the case on this machine. If it is the case, adding a circuit before the loader valve would have unregulated pressure.

 

[Burns331]

What do you mean PBY sleeve? I was going to add a PBY circut infront of my new valve. And just have a short circut hose that will loop back into the system when im not using PBY.

 

[Burns331]

Also there is a nice 13GPM Dual stick valve for sale locally to me for $150 brand new. I cant see why having an oversized flow rate would hurt anything. Just having an undersized one.

 

[RickB]

Be aware of the location of your system relief valve in the current system. If it is located in the pump outlet you have no worries. If it is located in the existing control valve it is imperative that the valve you add has its own relief valve built in.

 

[BukitCase]

Please re-read RickB's warning above; if you ignore it, you'll likely need to add the cost of a NEW HYDRAULIC PUMP to your estimate. This is NOT "internet fact", this is a "man, I wish I'd figured this out FIRST" fact...

also, your new valve should be as close to the size of other components as possible. DEFINITELY no smaller when main flow will be going thru it, and pref. not much larger. If you use your tractor for as many different projects as I do, wanting that "feathering" ability will become obvious to you... Steve

 

[ptsg]

I'm with RickB. I would rather install the new valve after the loader valve. That way, you know for sure that there is a relief valve before everything else.

As pointed out above, a big valve it's very hard to feather the controls. This means, once you move the lever, it goes all or nothing, while on a close matched valve, you can feather the valve easily.

 

[old and tired]

....a short circuit hose that will loop back into the system when im not using PBY.

There is no "loop", everything is in series... one after another. Your tractor is always "using PBY" - high pressure flows through every valve until one of them needs it...