Design-your-own 3rd Function

[aeblank]

So my dad would really like a 3rd function on his tractor, but the $600+ ($1,000 even) is hard-ish to justify. Though one guy sells them on ebay for $485, and maybe that's a great price.
I've always thought a roll-your-own would be doable, it is just a hydraulic solenoid afterall.
I feel like I've read enough to be dangerous/know what I would need to spec.
I've never seen anyone post, specifically, what they used. I thought I'd try.
I do know some about hydraulics, but it's more difficult when you don't fully know the system you're tying into.

So anyway, I think I know what I want:
2 spool
open center (allows flow through when neither spool is active)
10GPM capacity
1/2"-ish ports (?)
Standard JIC fittings/pressure (is it 3,000 or 3,500, I can't remember?)
Not sure what it's called, but you want the valve to hold the cylinder when not active.

So basically after the loader valving, there is the return to tank, and it is at pressure. The new valve is in series with that. As such, it has flow available, when the solenoid is active but otherwise the fluid goes back to tank, just through a longer path. The hose that goes to tank gets pulled off and goes on the new valve, and the old tank port is now the feed for the new valve. The outputs of the new solenoid go to the front of the tractor to be hooked to a cylinder, or whatever else. I'd need to sit down to actually draw out the solenoid path functionality (in order to let the fluid out of the non-pressure side of the cylinder).

Sound right-ish?

A quick search (not going back to any of my hydraulic suppliers of old) shows a valve and suggest a block. Seems like a reasonable combo:

12 VDC 10 GPM CC DA SOLENOID VALVE
1 STATION DO3 PARALLEL CC SUBPLATE

From there it is custom hoses, a little wiring, and a switch. True?

I do understand that the hoses/fittings could probably cost another $100 without a whole lot of difficulty. The switch probably wouldn't be as nice as the pre-molded handles either, but I don't think I'd like those anyway, so some stalk-mount switch would have to be made/spec'd.
Even so, that's maybe $250-300 vs well over twice that for a kit.

Anyway, curious what MFG / PNs people have used, or what the kits include for a little reverse engineering.

 

[J_J]

Is your tractor a closed center tractor?

 

[kennyd]

Sure, you can build a home brew setup for less as many do, but I think you estimate is quite low. Getting custom hoses made then adding in fittings/QD's will be a lot more that $100.

The valve you linked is for CC (closed center) hydraulic systems, and since you didn't mention what machine your father has we can't say if that is the correct valve or not. Also don't forget the two special Hirschmann connectors needed for the EL hookup.

 

[roadhunter]

You will probably find that there is not nearly as much markup as you originally thought once you buy all the stuff you need and spend the time to make it all work.

 

[J_J]

12 VDC 10 GPM OC DA SOLENOID VALVE

1 STATION DO3 SUBPLATE OPEN CENTER

HIRSCHMANN CONNECTOR

Some hoses and fittings.

 

[MtnViewRanch]

Is your dad paying for this? Maybe ask him what he actually wants instead of spending all your time trying to do it cheap and that isn't even what he wants.

Does he really want a true 3rd function, or would a diverter 3rd function workout just as well for him, maybe even better?

All things to consider.

 

[J_J]

What is the tractor brand and model?

 

[aeblank]

Dad has a Kubota L3710, and I have an L3940.
As much as anything, this is me learning about the hydraulic system on my tractor. I'm an engineer, what can I say?
So, for instance, how do I know if it's an open center, or closed center?

Maybe the kits are a "good deal", but some thing I want to prove to myself. It's easy to find the guy who says "just pay the professionals to do it". Those guys are boring and must have more disposable income than me. I built my own house, own garage, installed my own (awesome) heating system, put in an auto-lift, and designed any number of automotive, military, and industrial products. I know what *every* component in my heating system does and why. I'm not a hack, and I enjoy learning/knowing/doing it myself.

No diverter, thanks. I suppose it could work, but it seems that it's also a solenoid valve, so it seems the cost would be similar. I guess you mount those on the FEL, so you save some hose $$ ?

Pretty entertaining, I said open center in my post and posted close center products. DOH.

So, from your post/links J.J. (thanks!)
open center.
work ports blocked in neutral (that must be the term I was looking for)
Spring centering, also seems logical and important.

3/8" ports Seems fine. Match hose size to source. hoses to FEL can be 3/8.

Further thoughts?

 

[MinnesotaEric]

So my dad would really like a 3rd function on his tractor, but the $600+ ($1,000 even) is hard-ish to justify. Though one guy sells them on ebay for $485, and maybe that's a great price.
I've always thought a roll-your-own would be doable, it is just a hydraulic solenoid afterall.
I feel like I've read enough to be dangerous/know what I would need to spec.
I've never seen anyone post, specifically, what they used. I thought I'd try.
I do know some about hydraulics, but it's more difficult when you don't fully know the system you're tying into.

So anyway, I think I know what I want:
2 spool
open center (allows flow through when neither spool is active)
10GPM capacity
1/2"-ish ports (?)
Standard JIC fittings/pressure (is it 3,000 or 3,500, I can't remember?)
Not sure what it's called, but you want the valve to hold the cylinder when not active.

So basically after the loader valving, there is the return to tank, and it is at pressure. The new valve is in series with that. As such, it has flow available, when the solenoid is active but otherwise the fluid goes back to tank, just through a longer path. The hose that goes to tank gets pulled off and goes on the new valve, and the old tank port is now the feed for the new valve. The outputs of the new solenoid go to the front of the tractor to be hooked to a cylinder, or whatever else. I'd need to sit down to actually draw out the solenoid path functionality (in order to let the fluid out of the non-pressure side of the cylinder).

Sound right-ish?

A quick search (not going back to any of my hydraulic suppliers of old) shows a valve and suggest a block. Seems like a reasonable combo:

12 VDC 10 GPM CC DA SOLENOID VALVE
1 STATION DO3 PARALLEL CC SUBPLATE

From there it is custom hoses, a little wiring, and a switch. True?

I do understand that the hoses/fittings could probably cost another $100 without a whole lot of difficulty. The switch probably wouldn't be as nice as the pre-molded handles either, but I don't think I'd like those anyway, so some stalk-mount switch would have to be made/spec'd.
Even so, that's maybe $250-300 vs well over twice that for a kit.

Anyway, curious what MFG / PNs people have used, or what the kits include for a little reverse engineering.

Presuming you have an open center pump, you want this D03 valve and subplate with SAE #6 and fun, little LED lights in your electrical connectors so you know if you have power to the solenoids. The DIN style valve also allows you to spin the solenoids sideways 90 degrees if you have clearance issues.

FWIW, joysticks cost about $150.00 unless you make your own. The sub plate at the link I provided with require a total of (4) SAE #6 to 3/8 NPT (or whatever you want to have on the ends of your hoses to screw on). Plan on spending an additional $25.00 for those adaptors. Your local custom hose guy very likely has the adaptors but if not, surplus hydraulics does and they sell on ebay as well.

Hoses can be inexpensive or major bucks depending on their quality. Also you want two sets of QDs so if you remove the loader, you can detach your 3rd function.

 

[aeblank]

Presuming you have an open center pump

How does one know such things? What does that even mean?

Your local custom hose guy very likely has the adaptors but if not, surplus hydraulics does and they sell on ebay as well.

Parker store 2 minutes away from work. Not the cheapest, but good stuff. Though, they've started making their fittings in China too. Grrr. If I wanted that, I could buy the cheap brands.