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.

 

[J_J]

How does one know about hyd, you say, manuals, books, DVD's, hyd courses, YouTube videos and you can learn a lot on forums like TBN.

Also, just your questions here and someone should be able to answer.

Your manual should tell you about your hyd system.

But anyway, you and your dad's tractors are open center hyd systems, where the pump is pumping all the time the engine is running.

All valves are in series.

The pumped fluid passes through all valves to tank when the levers are in neutral.

When you move the levers, you re-route the fluid to the hyd component be it a cyl or hyd motor.

Some of the hyd valves are for convenience. You select the type valve/spool to accomplish the task.

If you want float, select a spool that has float.

If you want to control a hyd motor, you select a motor spool.

If you want regen, you select a valve with a regen spool.

A lever type valve will let you feather the valve for slow and precise work.

A solenoid valve works fine in some situations, and is usually full flow.

The GPM's pumped is dictated by the engine rpm.

You can probably get everything from here.

Surplus Center

http://www.baileynet.com/categories

 

[MinnesotaEric]

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

Closed center is like the water system in your house: always under pressure and fluid does not move till the valve is opened. Open center is like a spray pump where the water goes round and round the system till it is needed, then diverted off in another direction by a valve.

 

[kennyd]

Closed center is like the water system in your house: always under pressure and fluid does not move till the valve is opened. Open center is like a spray pump where the water goes round and round the system till it is needed, then diverted off in another direction by a valve.

:thumbsup: Great explanation Eric!

 

[aeblank]

Closed center is like the water system in your house: always under pressure and fluid does not move till the valve is opened. Open center is like a spray pump where the water goes round and round the system till it is needed, then diverted off in another direction by a valve.

Are any variable pumps, or all fixed displacement?

The above seems like constant pressure for the first, and constant flow for the second...... Or they're fixed displacement. =)

 

[J_J]

Excerpts:

Open center circuits use pumps which supply a continuous flow. The flow is returned to tank through the control valve's open center; that is, when the control valve is centered, it provides an open return path to tank and the fluid is not pumped to a high pressure

Closed center valve type, where the pump flow is blocked when valve spool is in neutral. When LS-valves are used combined with fixed displacement pumps, a special valve is incorporated in the inlet section of the the valve block to unload the pump, making the system work as an "open center" but the valves are still closed centers in neutral.

Variable speed pumps are used in hydrostatic transmissions.

NO flow or pressure through the pump in neutral except the charge flow, which is about 10% of total flow.

 

[Rocky Hoffler]

I put one on a 3700 Kubota had a 3 stack valve took two of the sections off and used only one had a hard time finding a control so I uased a pendant from a winch there is a very good info video on you tube just search third function valve usaed bosch relays to control the solenolds as my pendant was not real heavy duty I believe the valve was a Do5 its what I had but a smaller Do3 is what must folks use had a little problem with mounting it out of the way so as not to interfere with brake pedals my tractor was hydrostactic so who uses brakes any way

 

[J_J]

The L3700 attachment pump had a flow of 6.8 gpm.

D05 was over kill, besides more expensive.

 

[MinnesotaEric]

Excerpts:

Open center circuits use pumps which supply a continuous flow. The flow is returned to tank through the control valve's open center; that is, when the control valve is centered, it provides an open return path to tank and the fluid is not pumped to a high pressure

Closed center valve type, where the pump flow is blocked when valve spool is in neutral. When LS-valves are used combined with fixed displacement pumps, a special valve is incorporated in the inlet section of the the valve block to unload the pump, making the system work as an "open center" but the valves are still closed centers in neutral.

Variable speed pumps are used in hydrostatic transmissions.

NO flow or pressure through the pump except the charge flow, which is about 10% of total flow.

That is an excellent description. Way better than the slurpy machine at the 7-11 I had been thinking of using.

 

[Rocky Hoffler]

the d05 valve was more expensive buy I guess I didn't mention it was free cheap is good but free is better

 

[oldnslo]

Some things to consider when using electric operated valves like D03 or D05:
1) Will the "tank" port be pressurized? If yes confirm that the valve you selecting is rated for working pressure in the tank port.
2) Solenoid operated valves provide no metering for slow controlled load movement. They are on or off like a light switch. if you want the ability infinite speed control these are NOT the valves of choice.
3) Coil termination: Hirschman connectors are very common but corrode over time in wet environments. Pre-molded cables reduce this problem. Deustch connectors are sealed much better but usually require special tools to assemble the wire ends or purchasing pre-made cables. Deustch are also less common on industrial style D0* style valves.
4) Spool type Vs pressure drop: Typically the tandem center spool (P to T, A & B blocked) has the highest pressure drop and lowest flow rating of any spool in a given valve size. In open center series circuits the fluid is always flowing so pressure drop = energy loss and heat generation.