Custom hydraulic backhoe thumb

[avc8130]

I like this for the switch:

Cpi Weatherproof Switch, Push Button B7151-516 | Zoro.com

Zip-tied to the handle so you can hit it with your thumb is very ergonomic. I have 2 on my Kubota. One for the thumb on the hoe and one for the diverter up front.

ac

 

[bumperm]

Zip-tied to the handle so you can hit it with your thumb is very ergonomic. I have 2 on my Kubota. One for the thumb on the hoe and one for the diverter up front.

ac

Good find!

That looks quite weatherproof. The switch I and Racerwannabe used doesn't look so, but is also waterproof according to the description on Amazon:

Amazon.com: Alpinetech 19mm 3/4" Waterproof Momentary Stainless Steel Metal Push Button Switch Screw Terminal Extended Button Normally Open 1NO: Automotive

The downside of the switch we used is "some assembly required", in that a mount of some sort needs to be fabricated - that may also be a plus, as one can build a mount to suit (though it took me two tries).

As you said, the rubberized switch lends itself to an easier zip-tie installation and there's significant appeal in that. I suffer from the, "I can make that!" syndrome - a sickness, but one that has served me well :c).

 

[Racerwannabe]

Good find indeed!

I'm going to look into that

 

[Racerwannabe]

I have 2 on my Kubota. One for the thumb on the hoe and one for the diverter up front.

AVC: Could I trouble you for a photo of both switch installs? Anything you would do differently? A bucket grapple may be in my future too.

I spent three hours on the machine yesterday pulling rocks and stumps on the snowmobile trails. That hydraulic thumb is AWESOME and really speeds up the work. What a great mod!

 

[Racerwannabe]

Thumb switch 2.0



Mounting block slips over shaft and stays there with two set screws. Zip ties best thing I could come up with to keep the switch on the block

Mo' betta :thumbsup:

 

[BukitCase]

Racer, it's hard to tell from the pic so if you've done this, ignore me :laughing: BUT, if that's gonna be your PERMANENT temporary fix (and a nice one), you might wanna use one of these

Irwin Tools 1877715 Countersink Drill Bit, 3/8-Inch, Black Oxide - - Amazon.com

in each hole, your zip ties will probably last about 3-4 times as long... Steve

 

[avc8130]

Thumb switch 2.0

View attachment 452479

Mounting block slips over shaft and stays there with two set screws. Zip ties best thing I could come up with to keep the switch on the block

Mo' betta :thumbsup:

I guess you don't need that pic any more .

I'm so sorry for not posting one. I just never remembered when I was out by the machine.

ac

 

[Racerwannabe]

Racer, it's hard to tell from the pic so if you've done this, ignore me :laughing: BUT, if that's gonna be your PERMANENT temporary fix (and a nice one), you might wanna use one of these

Irwin Tools 1877715 Countersink Drill Bit, 3/8-Inch, Black Oxide - - Amazon.com

in each hole, your zip ties will probably last about 3-4 times as long... Steve

Great idea. Have one of those, just didn't think to break the corners of the holes. Will get 'er done!

 

[Racerwannabe]

I guess you don't need that pic any more .

I'm so sorry for not posting one. I just never remembered when I was out by the machine.

ac

No worries ac. Part of the fun is coming up with the design on your own. In this case, I was very constrained by the size of the scrap of aluminum bar stock that I had kicking around in the shop. That block has some tooling marks on the other side that I couldn't avoid. If my OCD really kicks in this spring, I might have to butter them with Bondo and paint the thing. Right now just having a ton of fun playing with the thumb to rip out stumps and rocks before the ground freezes (which will likely be tonight!)

 

[arkydog]

boy, i hope i can get someone to help. i get confused easily an have read this thread probably 10 times and have figured out that the diverter valve for my bh77 mechanical thumb needs a sv08-24-t6-n-12ds. i can't figure out which hydraulic cylinder with the least amount of re-work i should order. a part number and from where would be greatly appreciated. my stroke and healed broken rt. ankle has me limited getting on and off the backhoe to change the thumb setting. i can get a neighbor to do some welding for me which is a help. i would appreciate any information. even a pm would be great.

thanks rob

 

[dfkrug]

i can't figure out which hydraulic cylinder with the least amount of re-work
i should order. a part number and from where would be greatly appreciated.

To get it to work right, you will need to customize a cylinder, or the thumb. Since you have welding
help, which do you prefer?

 

[cic317]

Great thread!
Have a Yanmar CLB-40 and have wanted to add a thumb, this looks to be the perfect solution.Lot's of great info here, thanks to all for sharing!
Don't have the time to fabricate thumb set up from scratch, has anyone used a standard off the shelf hydraulic thumb for this project? If so any in put would be appreciated.
Thanks

 

[dfkrug]

...has anyone used a standard off the shelf hydraulic thumb for this
project?

There are no real standards when it comes to thumbs. There are some mechanical thumbs that
you can bolt on, but you really need to customize a thumb for the tractor, esp a hydraulic thumb.

That said, what a fine industrial tractor, the Yanmar CBL40. Does it have an extra valve on the
hoe, for an added function (thumb, auger, breaker, etc)? What is the system hydraulic pressure?
My guess is it runs at about 3000psi for the FEL and hoe.

Finally, what are the extra 2 holes in the dipper for?

 

[arkydog]

i have the kubota mechanical thumb installed already on my bh77 backhoe, but i 'm i guess not smart enough, to figure out the hydraulic cylinder that i need. i wa hoping that someone that had already built one with same configuration wouldn't mind telling the part # and and what kind of cylinder brand to buy. thanks ahead of time.

 

[cic317]

There are no real standards when it comes to thumbs. There are some mechanical thumbs that
you can bolt on, but you really need to customize a thumb for the tractor, esp a hydraulic thumb.

That said, what a fine industrial tractor, the Yanmar CBL40. Does it have an extra valve on the
hoe, for an added function (thumb, auger, breaker, etc)? What is the system hydraulic pressure?
My guess is it runs at about 3000psi for the FEL and hoe.

Finally, what are the extra 2 holes in the dipper for?

Been happy with the machine, Basically a stripped down version of the JD 110 TLB, 2nd owner mostly used on my property but has been dug a few small foundations already. I don't believe a bolt on would work for me, I tend to work my equipment a little hard. I have welding set up so that wouldn't be a problem. Unfortunately the machine is bare bones, No aux. hydraulic set up. That's why I was thrilled to find your posts, seems it would be a good set up for me without becoming a major project, time is scarce lately.So That is why I hoped to use an prefab hyd. thumb and then add your hyd. setup to it.

According to manual the backhoe runs between 3400-3675 psi, FEL is 2350-3000 psi. Didn't realize till now it has 3 separate hyd. pumps.

As to the extra holes, couldn't tell you, mine doesn't have them.

Wouldn't mind any additional input- Thanks!

 

[dfkrug]

...Basically a stripped down version of the JD 110 TLB...

Although it has a similar Yanmar engine as does the JD110, I don't see anything else it
might share with the Deere. It did compete in the same segment, smaller industrial TLBs.

AUX valves were optional, as I recall.

I knew the CBL40 has HST drive, and a 2-pump hoe, but doesn't the implement hyd pump
that powers the FEL also power the hoe?

I am not a fan of bolted-on thumbs, and esp not a hyd one with all that force at your
command.

As I pointed out near the beginning of this thread, I would get a welded cyl of the same
diameter as your bkt cyl, and design the thumb around it. That way, you do not have
to modify the cyl, and you can decide where to put the thumb pivot to achieve
the open/closed geometry you need. You have to fabricate a thumb anyway.

On that machine, I would use pivot pins of 1.5" diameter and 1/2" plate steel.

 

[arkydog]

it would be easier to modify the hydraulic cylinder than the thumb. i'm can't figure out the "coding" of the hydraulic cylinders to get one that can be ordered to modify. any help would be appreciated. if measurements are needed i can get them off of the factory thumb and backhoe.

 

[dfkrug]

it would be easier to modify the hydraulic cylinder than the thumb.

Ya think? Based on your above posts, you seem to think you can just buy a cylinder, and maybe
customize the ends on it. Not so. If you already have a mechanical thumb and hope to use its
existing pivot holes, you will have to not only adapt the cylinder's ends, but you will have to
shorten the cylinder and rod of a longer off-the-shelf cylinder.

In CIC's case above, there is no mechanical thumb to adapt, so making a thumb to work
with an off-the-shelf cylinder is the way to go. Making the thumb from scratch to be a
mechanical one or a hyd one is the same work.

 

[arkydog]

maybe your not understanding me or I'm not understanding what you are trying to say.... i already have the bh77 back hoe with the factory kubota mechanical thumb installed on the backhoe. I'm wanting to convert the mechanical thumb to a hydraulic thumb and am wanting some help figuring out which hydraulic cylinder to get to convert to hydraulic. i just can't figure what hydraulic cylinder to start with. does that make more sense.

 

[Ron50]

I have the Ansung model BH76 which is similar size to kb77 I think. From info I got here, I ordered from Surplus Center one that measures out to work to convert my thumb from manual to hydraulic. Item # 9-8760, '2.5x13.25x1.25 DA Hydraulic Cylinder' 159041 XHo411. Price was $70.