BH77 - has anyone considered converting mechanical thumb to hydraulic?

[briandantz]

I was out stacking wood... thinking.... " I bet I am going to see some Photos from Bump"!
1) Two inches extra really pushed the thumb around.
2) I see you added your spacer, very nice. The side port is out from behind the bracket now too (if you ever need to get to it) and the thumb is plenty clear of the cylinder.
3) i still haven't installed my solenoid cover yet. No good reason why, just busy.
4) Nice ripper, heavier duty than I expected. Real nice.
5) See the wear mark on the thumb about two inches down from the wrist pin (about halfway between the pins)? Another Kubota free feature. I think the base of the thumb hits the bucket when you go closed before the tips touch. I have the same problem starting. I will mark mine with a Sharpee marker tomorrow and show you where the interference is. This is a Kubota design error and has nothing to do with the Hydro addition. They hit with the Manual linkage too.

I have to start using Photobucket . Your photos post so much better. I also owe you some photos of my new Android App Mini Mill DRO i just built. "DRO on the Cheap".

 

[briandantz]

Hey Bump,
How is the ripper working for you? I haven't been on here for a bit.
My thumb has been great. so handy.

 

[bumperm]

Brian,

The Bro-Tek ripper works very well, allows the hoe to pull out roots with more authority than with my 10" bucket. That said, there is a minor problem when combined with the thumb. While the thumb comes up into the 10" bucket nicely, as grabs saplings and roots when you want to pull them out with the swing or by extending or retracting boom, the pincer action of the ripper with the thumb has a problem - the ripper has a curved cutting edge while the thumb is essentially flat. There's a crescent shaped opening that's almost 4" at its widest, and it's right in the center roots and such slide right out.

The fix!

I just bought some 1/2 plate to make an anvil that will bolt onto the thumb (4 bolt holes). The anvil will have a curved surface to mate against the ripper cutting edge - I'll probably leave a 1/8 gap or so. Since the ripper (or bucket) and thumb both pivot on the same pin, the mate up is always the same, so the anvil can't damage the ripper.

In use, besides grabbing something "easy" to pull or tear, it should also be able to cut through stuff with one heck of a lot of force (Bwaa, haa, haa!).

It's winter so this project isn't at the top of my retirement to do list. I should get 'er done within a couple of months though. Bro-Tek should offer the anvil as an option. Rich, are you listening :c).

The Gap:

 

[JustBilly]

I got mine up and running last night and a quick test this afternoon. Woo Frickin Hoo! :cool2: Worth every bit of the time and $$.

2 x 10 cyl, 27' of 1/4" hose, some fittings and hose protector, all told, I'm into it for $250. All parts other than the QD's were from Princess Auto. I'd ordered extra male QD's when I did the remote install so I would have them available.

I cheaped out and ran them off one of my other pairs of rear QD's rather than a valve mounted on the BH itself. If I get fed up with having 4 hoses to connect and have an extra $500 burning a hole in my pocket I might switch but for now, I'm up and running. The only mods I've done that aren't easily reversible is to weld 2 mounts on for the hose clamps. If I ever needed to it would take me about 10 min max to remove this and put the mechanical linkage back on.

This is the cyl that will be replacing the mechanical linkage.
View attachment 330338

I have to cut the base mount off the cyl, turn it 90 deg and weld it back on and also narrow the head mount from 2" to 1.5". The base mount needs to be turned so the ports are on the side.
View attachment 330339

The ram was mounted and welded in place to ensure that the pin boss was perfectly in line with the cyl body.
View attachment 330340

The head mount needed to be narrowed to fit in the space of the old linkage
View attachment 330341

Lines were run on the outside of the stick and then go down inside the hole in the top of the boom
View attachment 330342

The width of the thumb actually provides some protection for the head port. Lines were plumbed direct to the ram, no QD's at this end as I never plan to use an auger etc.
View attachment 330343

The lines were fished thru the existing hose protector at the base of the main boom
View attachment 330344

I've got a 4 spool valve for remotes (3 rear, 1 future front) The BH is run off one pair with 3/8 couplers, the thumb is on the top 1/4" pair, easy to reach with my right hand by my left elbow.
View attachment 330345

Everything tucks in nice and tight from the operator's seat
View attachment 330346

If I leave the valve activated for the BH, I can still run the thumb but it is slow (flow is split between 2 open ports). If I neutral the valve powering the BH, the ram works nice and quick. This will give me incentive to order replacement detent kit that I lost the spring out of during install and have been using a cedar shim to hold open for now.

Can you send me the part number for the cylinder please?

 

[JustBilly]

I just got an email from the company that I've been speaking with after asking about the relief setup. I got this reply:

We don't usually do a cross-over relief system on the smaller backhoes (usually just on the larger excavators and backhoes), but I can definately look into pulling one together for you with pricing if you would like. On the smaller backhoes we size the hydraulic cylinder so that the column load of the cylinder can handle the breakout force of the bucket to avoid buckling.

The delay has been that they haven't been able to get their hands on a BH77 to get actual measurements off of. A while back, I offered to assist with getting them the dimensions if they had difficulty getting ahold of a BH77 at their local dealer, so they will be sending some dimension sheets for me to fill out and take pictures of my BH77 so they can get to working on a thumb kit for it.

I'll update this thread as I hear how things are progressing.

Pm sent

 

[bandit67]

Nearly 10 years after my original post looking for a hydraulic thumb conversion option, I finally ended up doing my own thanks to a couple of TBN members posting info on their custom built setup. I can't believe I waited so long to do the modification. It's been great having the hydraulic thumb for the last year and a half. I put a parts list together with links and photos if anyone still wants to do their own conversion - send me a PM with your email address. Short video of it in operation attached:

Kubota BH77 Hydraulic Thumb

Hydraulic thumb plumbing is split between bucket and thumb, tapped into bucket curl cylinder. It is activated using an electric solenoid valve. Much easier than running 2 additional hydraulic lines al

rumble.com

 

[Carl_NH]

HI Bandit,

Yes I am interested in the parts list to add this to my B21 - I have a modified mechanical Brotek thumb now - added 1/2" side plates and it has 1" pins now. What's been holding me back is the valving needed (adding valves to the internal stack) but with this setup it runs off the bucket cylinder.

I read the whole thread and Bumper, Brian and CDN have done a good job explaining the pros/cons and how they did it but if you can share the consolidated list that would be great,

This is a Gannon 16" bucket which I think is the same as the BH 77 - just need to get a new thumb. and hyd.

 

[Carl_NH]

Can you provide measurements from the bucket pivot point to the teeth on the BH 77 then the thumb length center of the pivot pin to end of the thumb fingers?

My B21 is 19" from the center of the bucket pivot pin to the end of the bucket teeth, and the teeth spacing is 4.5". I want to ensure the thumb is long enough and the thumb tines fit between the bucket teeth.

Thanks in advance!