Custom hydraulic backhoe thumb

[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.