Home brew 3rd function questions

   / Home brew 3rd function questions #1  


Super Member
Nov 25, 2016
Santa Cruz Mountains CA, Southern OR
Branson 3725H Deere 5105
I'm going to get a grapple for my Branson 3725 and will probably make the 3rd function setup myself. It's looking like the loader's torque tube may be the best bet for locating the solenoid valve. The other possible locations are under oil filters or block access to the fuel filter and engine dipstick. The disadvantages that I can see are that it's more likely to get damaged, and I have to run long hoses out to it and those will carry pressure all the time as they're P and T lines. The valve would be in line between the dealer installed rear aux valve and the factory rear aux valves whose T line goes to the 3pt. The 3725 puts out 10.3 GPM. The charts I've looked at would indicate 1/2" hose for 10gpm. But the dealer installed 3rd rear valve has 3/8 between it and the loader valve. Should I use 1/2" to my 3rd function valve? Should I replace the dealer installed lines with 1/2"?

I realize that putting the valve on the torque tube puts it out in harms way, I will probably make a guard to keep branches from poking it.

The P and T lines to the 3rd function valve will have couplers roughly where the loader valve couplers are for removing the loader. I will make them so that they can be connected together to bypass the 3rd function. I'm a little worried that I or someone else (future owner) would disconnect the loader and forget to connect the bypass. Which would make the system deadhead. Does deadheadding for a few minutes until you figure out what's wrong hurt anything? If so are there connectors that would automatically make that bypass when disconnected?

One more dumb question. There's two kinds of solenoid valves I see- one central box for the electric connections like this:
or two separate boxes like this:

What's the difference? Is there anything in those boxes?

BTW thanks to guys like N2Dfire and aerojunkie who have posted their home brew third function process and everyone who helped them out.
   / Home brew 3rd function questions #2  
I have no experience with this, but from what I have read I think you need this kind: Hydraulic solenoid operated selector diverter valve 12 volt DC - Fremont Industrial Supply

   / Home brew 3rd function questions #3  
The pieces that you have mentioned in your post are electrically operated hydraulic control valves when activated you will get full flow instantly
and be slamming your grapple shut and open with no ability to modulate it and gently close or open it, the seconds posting is more like what most
people would use the two supply ports would be plumbed to your existing usually bucket curl lines with the two normally open ports piped to your
bucket curl and the other two normally closed ports to your grapple, to use it you would activate your switch to operate the valve then using
your curl valve operate your grapple releasing the switch to go back to your bucket curl function.
   / Home brew 3rd function questions
  • Thread Starter
People use both 3rd function and diverters for grapples. At 10 gpm it'll take about half a second to open or close the grapple If I did the math right. It's probably less than the 10gpm the pump produces at that point but I don't know how much less. I was figuring that I could put adjustable one way restrictors in the A and B lines to slow the grapple's response if it is fast.

The ergonomics for the diverter seem like they'd be weird to me. Also you can't curl the grapple and close it at the same time.

If I went with a diverter most of my questions are moot as it's not in the main circuit.

I could be fancy and get a porportional control valve along with the appropriate switch and control board. It's probably expensive though.
   / Home brew 3rd function questions #5  
   / Home brew 3rd function questions #6  
I have no experience with this, but from what I have read I think you need this kind: Hydraulic solenoid operated selector diverter valve 12 volt DC - Fremont Industrial Supply

View attachment 524037
This style valve is what I have to operate my grapple and auger on the front loader. I also have a similar setup running the thumb on my 15,000 pound excavator. Plumb the lines into the bucket curl and dump lines. Then you only have to move your finger or thumb on and off the loader's joystick button to move the grapple. Moving one function at a time is no problem. Plumb the grapple lids to close with the same curl movement of the joystick and open the lids with the same movement to dump, you only have to move your finger on and off the button to close the grapple lids or tilt the grapple up. I've been using my grapple for 5 years this way and there second nature with no learning curve when I run my thumb on my excavator.

Also, grapples only need 1/4 inch lines to operate a grapple. 3/8 inch lines at most.
hugs, Brandi
   / Home brew 3rd function questions #7  
My opinion FWIW is that a true 3rd function valve should be mounted on the tractor, not up on the torque tube of the loader since the P and T lines are flowing constantly. Yes, deadheading the system for “a few minutes” can damage the system if the PRV (pressure relief valve) is not working 100% and the fluid may overheat as well.
   / Home brew 3rd function questions #8  
Hey Eric,

Thanks for the props already. I'm just glad the information has been helpful to others.

For your situation as far as mounting location if you're thinking Diverter then the torque tube might not be *that* bad just be sure to mount it as protected as you can (a guard is a great idea). If you're going 3rd function then I would try to find somewhere much closer to the "core" of the tractor (and more protected) - I have even seen some set-ups where the valve was mounted on the rear of the tractor (near the top link mounts) and some under the hood just behind the "firewall" The biggest issue is being able to route the hoses.

As you probably already read, I used 1/2" for the P & T lines between the loader valve, 3rd function valve, and 3pt on the tractor & then 3/8" lines to the torque tube for the grapple. This restriction will slow the operation of the grapple down some by itself. You can also add flow restrictors if more reduction is needed.

As to your question about the different valve wiring - I used the top single box style and there's nothing inside there except the screw terminal for ground and the two positive terminals (one for each coil) - the only real advantage I can see is not having to run a separate ground wire to each coil on the dual connector style (and possibly any size / orientation issues)

As the old saying - to each their own but personally I would not make the 3rd function "bypass-able" - I would plumb it in series somewhere between the loader valve and the 3pt like the other aux valves are already. I would put disconnect on the lines to the torque tube where ever your factory loader disconnect valves are.

The only other advice I can offer is design it over and over on paper & in your head before you start. Measure everything twice & then measure it again. Make sure you have all the little fittings to go between everything. You'll still run into some gotcha somewhere but hopefully with good planning it will be minor.

Best of luck and don't be afraid to ask questions.
   / Home brew 3rd function questions
  • Thread Starter
Thanks! I learned a lot from your writeup. I agree that the tractor's the best place for the valve but I'm having a hard time finding room where it's not in the way of something or under an oil filter. Last night I figured out a really clean way to do a diverter by breaking into the curl circuit's hard pipe tees out on the loader. But after reviewing a couple threads about diverter vs true third function I'm still thinking the true 3rd would suit me more.