Custom hydraulic backhoe thumb

[avc8130]

If those valves are the correct function, then try them. When I was looking, most of the solenoid valves on eBay
required a manifold or were poppet-type valves, not spool-type. The L45 is a bigger CUT and has bigger cyls,
allowing for more mounting space.

I like that custom hardline you made.

As long as it shows up and is the actual PN they claim, it has the proper function. I think the only differences between it and what you chose are the GPM rating and I believe it is NC and yours was NO. So basically the electrical function is opposite but that shouldn't matter.

Custom hardline? That is 100% Kubota there.

ac

 

[dfkrug]

I think the only differences between it and what you chose are the GPM rating and I
believe it is NC and yours was NO. So basically the electrical function is opposite but that shouldn't matter.

Mine is NC (normally closed), but either will work. Since the thumb is not used more than half the time, I
designed for OFF or NC. Since these solenoids have 100% duty cycle, it is OK to have them ON most of the
time, then OFF for when you want to use the thumb/grapple.

HydraForce has a very nice PDF catalog that shows all the models and codes.

 

[IslandTractor]

I am wondering about whether it would be possible to rig a simple system that would permit the bucket and thumb independently. If two of these on/off valves were stacked in series, would it be possible to rig 1) bucket only, 2) thumb only and 3) simultaneous operation. I cannot quite envision how this might work but wonder if some of you with more experience could figure out how to plumb that using the simple valves we have been discussing.

 

[avc8130]

Mine is NC (normally closed), but either will work. Since the thumb is not used more than half the time, I
designed for OFF or NC. Since these solenoids have 100% duty cycle, it is OK to have them ON most of the
time, then OFF for when you want to use the thumb/grapple.

HydraForce has a very nice PDF catalog that shows all the models and codes.

Mine is normally closed also. It must have been the other guy with the BH77 that used a normally open.

I don't think it really matters in the long run.

ac

 

[avc8130]

I am wondering about whether it would be possible to rig a simple system that would permit the bucket and thumb independently. If two of these on/off valves were stacked in series, would it be possible to rig 1) bucket only, 2) thumb only and 3) simultaneous operation. I cannot quite envision how this might work but wonder if some of you with more experience could figure out how to plumb that using the simple valves we have been discussing.

Of course it IS possible, you'd need another valve on the curl to isolate it "off". I don't think it would gain you much.

You can isolate with the proposed setups to use the bucket any time you'd like. You can also "place" the thumb by locking the valve and it should hold any position you'd like. I'm not sure what advantage being able to move the thumb 100% separately would truly provide, but maybe something will come up in practice.

From what I can tell, and I haven't done it yet myself so my opinion is just theory based, this is a very cheap way to get a functional thumb. If it has limitations, I'll probably be more than willing to live with them knowing I saved $1500 on the hydraulics alone. I can and will use those savings to buy another implement.

ac

ac

 

[IslandTractor]

Of course it IS possible, you'd need another valve on the curl to isolate it "off". I don't think it would gain you much.

You can isolate with the proposed setups to use the bucket any time you'd like. You can also "place" the thumb by locking the valve and it should hold any position you'd like. I'm not sure what advantage being able to move the thumb 100% separately would truly provide, but maybe something will come up in practice.

From what I can tell, and I haven't done it yet myself so my opinion is just theory based, this is a very cheap way to get a functional thumb. If it has limitations, I'll probably be more than willing to live with them knowing I saved $1500 on the hydraulics alone. I can and will use those savings to buy another implement.

ac

ac

I certainly agree this is a great bang for the buck solution. I guess I was just wondering what it would take to make it more flexible.

Why move the thumb independently? Well, when picking up some items it might be desirable to accurately place the bucket and then close the thumb. Let's say you were dismantling a stone wall and wanted to pick stones off rather than pull the wall over. If you use the standard method, whichever steel hits the wall first is going to push it. If however you could accurately place the bucket just behind a stone and then close the thumb on it to secure, it would work better. Kind of like being able to accurately "pick up sticks".

I honestly don't know if having independent thumb control would be a big advantage or not. Certainly the cheap and dirty dual movement is WAY better than manual control. I'm exploring possibilities, not complaining.

 

[dfkrug]

I honestly don't know if having independent thumb control would be a big advantage or not.

The "classical" method of setting up a diverter valve to steal power from the bkt cyl is to use a 2-spool
solenoid valve. Then you have truly independent thumb control, or independent bkt control. Clearly,
there are some uses where independent thumb control is valuable, as you mentioned. Using this
same setup for independent JAW control on my 4-in-1 FEL bkt would also give me one capability I
do not have. Sometimes I want to open the upper jaw when the FEL is high and full of dirt.

The biggest reason I used a SINGLE spool valve was not to save money. It was so I could locate
the valve, which is tiny, up closer to the action and avoid routing long hoses. I get one capability
that the 2-spool diverter design does not have, and I lose one capability, too. A fair tradeoff,
given the hose advantage.

 

[IslandTractor]

Assuming I was comfortable running 1/4" lines from the operator station to the thumb cylinder, what "easy" options are there for installing a simple control valve that would permit independent operation of that cylinder? I wonder for example what it would take to parasitize one of the stabilizer lines (diverter valve?) that would leave the stabilizer in position while flow was diverted temporarily to the thumb. My understanding of hydraulic valving is really pretty naive so that might not be the reasonable approach. It seems however that there might be some home made solution intermediate between the now famous "dfkrug simultaneous operation" set up and the $1800 kit offered by Woods for independent control. Is a two spool solenoid valve necessary (seems to cost about $250 on surplus supply) or could a simple mechanical "solenoid" be used to divert flow to a separate control valve? As one would rarely adjust stabilizers once set, it seems plumbing something that would allow physically turning a valve from A to B at the operator station to divert flow might allow use of the stabilizer control itself to control the thumb. Is that nuts?

 

[avc8130]

Assuming I was comfortable running 1/4" lines from the operator station to the thumb cylinder, what "easy" options are there for installing a simple control valve that would permit independent operation of that cylinder? I wonder for example what it would take to parasitize one of the stabilizer lines (diverter valve?) that would leave the stabilizer in position while flow was diverted temporarily to the thumb. My understanding of hydraulic valving is really pretty naive so that might not be the reasonable approach. It seems however that there might be some home made solution intermediate between the now famous "dfkrug simultaneous operation" set up and the $1800 kit offered by Woods for independent control. Is a two spool solenoid valve necessary (seems to cost about $250 on surplus supply) or could a simple mechanical "solenoid" be used to divert flow to a separate control valve? As one would rarely adjust stabilizers once set, it seems plumbing something that would allow physically turning a valve from A to B at the operator station to divert flow might allow use of the stabilizer control itself to control the thumb. Is that nuts?

It's not nuts, it's possible. I don't see a lot of guys using mechanical valves around these parts, but I am sure it is possible.

You'd have to run the current stabilizer hoses to the new valve(s). Then hoses from that valve to the stabilizers. You'd also need hoses from the valve all the way to the thumb.

I have a feeling that the valve cost won't be the driving factor. By the time you buy the 2 long hoses I think hose cost will become quite significant.

My thought/plan is to install the single solenoid valve and have the thumb paralleled to start. This is SO much further ahead of the nothing I have now. I was about to hit the trigger for a mechanical thumb for $700. Then I saw this thread and realized a ~$50 valve would make the $1k hydraulic thumb possible. $1500 for the Kubota hydraulic valve/hoses was a complete show-stopper. $2500 for a hydraulic thumb was just never going to happen. I was so happy I could jump. (I might have.)

If this setup proves to be a "tease" and I want the full control, I'll worry about updating later. I'll have only sunk ~$50 in unrecoverable costs into the valves mentioned in this thread.

I'm really looking forward to the "pinch" thumb. My main use for the thumb will be picking up logs to cut for firewood. I have a rock retaining wall I want to relocate also. I have run through the operation in my head with this setup enough time to know I doubt I will miss the full control.

ac

 

[dfkrug]

I wonder for example what it would take to parasitize one of the stabilizer
lines (diverter valve?) that would leave the stabilizer in position while flow was diverted temporarily to the thumb.

It is completely feasible, IT.

You can get a 6-way, 2-circuit lever-operated diverter that would use flow from one outrigger. That WOULD reduce
your hoses along the boom to 2, and that's good.

I did a quick check and a manual diverter like this runs over $100, so it does not save much money vs. solenoid
diverters for the same task. If you put your solenoid diverters down near the operator, then you have more
flexibility re size and shape. I think you would get tired of manually switching whenever you had to move.

So....consider this valve, from the HydraForce catalog. One solenoid, six-way:
SV12-60 Spool-Type 2-Position, 6-Way Hydraulic Cartridge Valve

Not small in size, and I do not know what it would cost. You have to ask a disti.