3rd function valve

[J_J]

Are you sure you can operate a valve downstream if the loader valve is using all the fluid for cyl extension?

My thoughts here is that while the loader is extending at full flow, the rod side fluid is going to tank. There is no fluid to go downstream. However if the loader is only using half flow to extend the cyl, fluid will flow out the PB port for downstream operation.

The loader cyl do not use that fluid very long as the pump flow is diverted to the cyl. This only takes seconds, but during that time, the cyl expended fluid goes to tank, and if you go to relief, that fluid also goes to tank. No flow past the loader for a short period. When you let the lever go back to neutral, the flow path is restored.

For you in dis-believers, put a flow meter in the circuit and see for yourself. Is it not logical that there will be zero flow for a short time.

Ask yourself what would happen if you were running a hyd motor from the rear remotes and you used all the pump flow for the loader. Would the hyd motor stop or slow down?

A lot of you will not want to agree with me, but that is OK. I have been wrong before, and I know you don't want to be wrong either. .

 

[kennyd]

Kubota:



JD:

 

[kennyd]

Well I don't think we are going to find a definition written down anywhere. BUT In my pea brain, I always though the 3rd function was a description that related to a loader only as the loader has 2 functions, and when you need an auxiliary source of hydraulic power on that loader then you added a "3rd function". Now your loader has 3 functions.

And when people started getting this third function by various methods, people started saying things like "True" 3rd function to refer to the valve in the power beyond flow path so that the "3rd function" could operate at the same time as the other two functions of the loader. Example loader boom lowering, grapple dumping and opening the jaws all at the same time.
Which you could not do with a diverter valve for instance, where you switch the curl/dump valve on the loader between two paths with an electric over hydraulic valve and subplate controlled by an electric switch.

So this is not a "true" 3rd function, although it is a 3rd function. Not that it makes much difference as most of our CUTS may not have enough flow rate from the pump to really operate those 3 functions all at the same time anyway with much speed. Now as for the 3 mechanically operated spools for the loader.. no problem, still a 3rd function setup, and if the 3rd spool is in the power beyond circuit, it is a true 3rd function.

It does not matter that the "true" 3rd function is mechanically operated by a lever or whether it is electric over hydraulic. The point is it is giving you a 3rd function to the loader.
Same for the way I am operating my grapple with a downstream Selective Control Valve that is providing fluid to a remote on the back of the tractor and is plumbed to go to the loader.. it is a "true" 3rd function because it is in the power beyond loop and could be operated while the other two functions are in operation. Again it is mostly wishful thinking with CUT flow rates. I guess you could think of the diverter valve setup as a 2 1/2 function if you like

In my opinion this is rather academic and does not make much difference, and lots of people's opinions will differ on this. You have heard me ramble on now, lets hear what you all think.

Well said sir :thumbsup:

 

[k0ua]

Let me ask you a question that I am not sure of. When you operate a loader spool, which in my case you have: Prime mover, Pump, Loader control valve, Power Beyond port on the loader valve, to SCV (rear remote), 3pt valve, Tank. Now when you operate lets say the lift valve spool fully, now your loader arms are going up, is there any fluid flow path to the Power Beyond port or is it cut off? That is my question.

 

[k0ua]

I am going to answer my own question, in what I THINK from experience. I believe there is some flow to the PB port even if the loader valve is operated fully open to say raise the lift.. But it will be pretty slow, with the flow rates we see on CUTS. That is what I think.

 

[MtnViewRanch]

Kubota:
View attachment 364300


JD:
View attachment 364301

Thanks for the picture Kenny,:thumbsup: I don't know why my link doesn't work. :ashamed:

 

[J_J]

Let me ask you a question that I am not sure of. When you operate a loader spool, which in my case you have: Prime mover, Pump, Loader control valve, Power Beyond port on the loader valve, to SCV (rear remote), 3pt valve, Tank. Now when you operate lets say the lift valve spool fully, now your loader arms are going up, is there any fluid flow path to the Power Beyond port or is it cut off? That is my question.

My thoughts are:

When you fully engage, say the lift spool, you are blocking flow downstream and redirecting allthe flow to the cyl for a few seconds. If your two loader spools are series parrallel, you can use both spools and the flow will divide between the two spools. and nothing downstream for a few seconds.

If you only use part flow to the cyl, then you have some fluid downstream.

Everything coming out of the cyl is going to tank.

 

[J_J]

Thanks for the picture Kenny,:thumbsup: I don't know why my link doesn't work. :ashamed:

All that link tells me is that there is a 3rd function kit available. Do you think it might/could be used for something else.

If the solenoid and subplate kit is not used for the loader, do you still call it a true 3rd function.

I use the 3rd function term just to indicate there is a solenoid valve on a sub plate perhaps making it a true 3rd function kit.

There must be a problem with the terminology if one has to describe a valve as a true 3rd valve. What is an untrue 3rd valve.

This does not have to go further unless you all want to.

Perhaps someone will find the true definition of 3rd function.

I thought all my facts were fairly accurate. I know if they are not, you guys will surely set me straight. Don't beat me up to much.

 

[the old grind]

Not to hijack, guys, just trying to put out an example of what this er' friendly discourse applies to, and .. perhaps related later as to its control attributes .. with a grapple. :salute:

My lift & curl cylinders don't work well at the same time unless I'm dumping a load, so I can't guess whether they're series-parallel. Well, my 6 GPM pump is no great shakes, so I don't expect many things to happen all at once, and k0ua, I think I'm with you about o'all flow.

J_J thanks for the link to II! What appears to be the difference between the types offered is product title and fittings included more than what they can do, but the valve block for the 'true' kit doesn't look like a 6-port.

I wish I could compare similar valves s x s to see which is more compact, since I'll pro'ly need a shoehorn, splitting wedges, and moly grease to squeeze one onto my very compact tractor/FEL. Out of harms way and out of my way could mean on the far loader arm.

Is a the place to ask, what's the guess how much of my mere 6 GPM will be lost to adding re-plumbing a dozen connections with 90s or 45s?

 

[J_J]

You should not lose any GPM, maybe a few psi.

If you have 6 GPM, and try and use the lift and curl spools at the same time, the flow will be split and provide 3 GPM to each spool.

A true 3rd function single valve and subplate will probably have 4 ports. P,T, A,B.

The diverter valve will have 6 ports. Two lines in, Two lines for the grapple, and two lines for the curl cyl.