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...

 

[Tx Jim]

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.

I think adding 13 GPM valve on a 5.6 GPM one will loose ability to feather a hyd cylinder. Back many yrs before PBY was introduced I installed several hyd spool control valves(less PBY) on tractors with low hyd GPM output that had no problems & hyd systems operated fine. I'll guess a hyd system with 5.6 GPM capacity doesn't require PBY to operate correctly.

 

[ptsg]

The PBY is not related to the GPM. A 1 GPM system will require a PBY, like a 10 GPM will also require.

It's there to provide flow for the valves ahead as about 90% of the valves can't handle system pressure on the Tank side of the valve. It can crack the body.

Feeding other valves through the tank port, will also cause the relief valve on the first valve to be irrelevant. The relief valve, relieves the excess pressure to the tank port, if the tank port is also under system pressure, there is no place for the relieved pressure to go.

 

[rScotty]

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.

Most 2 lever Aux hyd. valves (typical for loader control valves) will have a power beyond or PBY port....but not all do. In order to utilize the PBY port, many makes of valves require a special internal PBY sleeve while other makes do not. Usually the valves that require them will come with the sleeve, but not always.

It sounds to me like you are looking for a "2 spool loader control valve with a power beyond port". Be sure to also get that power beyond sleeve if the valve description says one is required to use the PBY port. There will also be options for each spool valve to have a float postion if wanted. Sometimes it will be noted that the spool valve has a center off position.

I don't understand what you mean by a "short circuit" or "looped circuit". The way you originally described the system you want to build, it sounds like the hydraulic pump would be feeding directly into the "IN" port of the aux. valve set. Then the properly sleeved Power Beyond (PBY) port would be connected directly to the "IN" port of your normal loader control valves. The PBY port on the normal loader control valve would not be used... it would be blocked off. Both valves setshave return ports which return the used flow back to the hydraulic sump.

Frankly, I wouldn't plumb it the way I have described above .... which is how I think you originally described it. Instead, I would feed the existing loader control valve first and then use use the loader control valve's PBY outlet to feed the accessory valve set. That way you get more loader flow and the advantage of a known relief valve. However, plumbing that way does require that the existing loader control valve has a blocked off PBY port and that can convert to a usable Power Beyond port with the right PBY sleeve that fits it - if required. When required, the PBY sleeves are specific for each different valve brand - you have to get the right one.
Good luck,
rScotty

 

[Tx Jim]

The PBY is not related to the GPM. A 1 GPM system will require a PBY, like a 10 GPM will also require.

It's there to provide flow for the valves ahead as about 90% of the valves can't handle system pressure on the Tank side of the valve. It can crack the body.

.

ptsg
Please explain how the hyd systems on older tractors built in the late 40-60's had external control valves added to their existing hyd systems without catastrophic valve failures before PBY came into existent? . I'm referring to hyd systems on tractors such as Farmall H &M & JD 420 that I witnessed the hyd systems operating fine with added remote control valve without the aid of PBY.
Thanks,Jim

 

[rScotty]

ptsg
Please explain how the hyd systems on older tractors built in the late 40-60's had external control valves added to their existing hyd systems without catastrophic valve failures before PBY came into existent? . I'm referring to hyd systems on tractors such as Farmall H &M & JD 420 that I witnessed the hyd systems operating fine with added remote control valve without the aid of PBY.
Thanks,Jim

I don't know if you are asking me or just generally. But the answer is easy. I've worked on a number of those old Farmalls, JDs, Fords, and Masseys from that era. In fact I still own one.

Before power beyond porting became popular we didn't string controls together in series. Instead, we used a flow selector valve that would direct the flow to whichever system that you wanted to power at the time. The system that was selected at the moment got full power and flow and the other system nothing. So it was real common to have to reach down and throw that lever to select between running the 3pt or running the hay loader.

That system put a premium on having cylinders that would stay up and not leak down....but those kind of cylinders were easy for manufacturers to make. Especially when they only had to stand up to the lower pressure & flow hydraulics at that time. 1250 psi was the norm, and 3 to 4 gpm typical. After all, even on a 50 hp tractor of the time the hydraulics were originally only there to run a 3pt hitch. That doesn't take much pressure or flow even with a draft control dump valve added.

Anyone can still plumb a tractor that way. It's still the cheapest and easiest way to run accessory hydraulics. Just switch the flow and you are done. The cylinders don't move real fast, and it can be a pain if you need to work both ends of the tractor at the same time....and even worse if you want power steering (pretty much impossible). But hey, it sure beats doing all the work by hand.
rScotty

 

[Tx Jim]

rScotty
I didn't address my question to you but anyone that replies is fine. One hyd system I had 1st hand experience with that didn't have PBY was a '57 JD 420 that had a spool valve installed in hyd line that supplied oil to the 3 pt hitch. Both 3 pt & a hyd cylinder connected to breakaway couplers operated fine without engaging any other lever.

 

[rScotty]

rScotty
I didn't address my question to you but anyone that replies is fine. One hyd system I had 1st hand experience with that didn't have PBY was a '57 JD 420 that had a spool valve installed in hyd line that supplied oil to the 3 pt hitch. Both 3 pt & a hyd cylinder connected to breakaway couplers operated fine without engaging any other lever.

Yes, that's yet another way to solve the problem of using one pump to supply multiple systems. I've never seen it done with a priority valve, but that might work as well. It's just that without PBY, the plumbing has to be done so the operator can decide which system gets the flow.
rScotty

 

[Tx Jim]

On the JD 420 I referred to the pump flow traveled through the spool valve housing to the 3 pt hitch. There was no priority valve. If one desired to control hyd cyl move handle on spool valve,if one desired to operate 3 pt one moved rockshaft control lever nothing else was involved.

 

[aczlan]

On the JD 420 I referred to the pump flow traveled through the spool valve housing to the 3 pt hitch. There was no priority valve. If one desired to control hyd cyl move handle on spool valve,if one desired to operate 3 pt one moved rockshaft control lever nothing else was involved.

That would be plain Open Center, not Open Center with Power Beyond.
The advantage of Power Beyond is that in an Open Center system, if the 3 point it trying to raise, the spool valve has to create enough pressure on the output side to raise the 3 point AND do whatever work the spool valve needs to do.
A Open Center system with Power Beyond lets the "spent" fluid from each valve return directly to the tank and does not force it to do whatever other work needs to be done further down the loop.

Aaron Z

 

[Tractor Seabee]

TX, take a look at the 8 GPM valves Surplus Center has in their online catalog at www/surplus center.com. Their tech desk will help you make the right selection and options.

Ron