BH77 - has anyone considered converting mechanical thumb to hydraulic?

[jim_wilson]

I've got the BH77 WSM in pdf that I can email to you

Is that easy enough for you??

Yes it is!

Sent you a PM with my email address.

 

[Teikas Dad]

Subscribed

 

[jim_wilson]

I haven't forgotten about this - I've just been diverted by some other projects (tractor projects) for the last week or so. The next thing I need to do is finalize what size cylinder is needed for the thumb - and talk to a couple of places about what it would take/cost to get a custom cylinder made to fit the existing manual thumb.

The proper valve to use to work the whole thing is still up in the air too - but I've gotten some answers that might be helpful - I've just got to get the tables cleared off so I can get back to working on figuring this out.

 

[larma]

Please correct me if I'm wrong, but isn't the non-foot pedal control simply an electric solenoid? And IF that's correct, doesn't that leave you with ZERO FEATHERING ABILITY on the thumb?

Momentary Switch

FTFY

 

[jim_wilson]

Please correct me if I'm wrong, but isn't the non-foot pedal control simply an electric solenoid? And IF that's correct, doesn't that leave you with ZERO FEATHERING ABILITY on the thumb?

Momentary Switch

FTFY

I think that's what they were thinking of - the electric solenoid thing that is.

I'm honestly not sure what kind of feathering ability there is - or isn't with a valve controlled by a solenoid. There may be an ability to feather if the right kind of valve solenoid combination is used.

I've got a five simultaneous projects going on right now so I haven't been able to spend any time on the manual-to-hydraulic thumb project in the last couple of weeks. I found at least one place I should be able to get a custom hydraulic cylinder produced - and I have feasible plan to add a foot pedal and valve to control the whole thing - my last major sticking point is which valve to use - and how it would be hooked up (tie in with the 2 lines feed the hoe now - or is a separate tank return line needed)

I would rather stay "mechanical" for the thumb control (use a foot pedal instead of a solenoid) - because I think it would be more reliable long term. But that's just my personal preference.

 

[1savoy]

"I'm honestly not sure what kind of feathering ability there is - or isn't with a valve controlled by a solenoid. There may be an ability to feather if the right kind of valve solenoid combination is used. "

If using a solenoid valve, a flow restrictor (small orifice) fitting in one of the lines will slow down the speed and help with feathering. I used one on the grapple I built and it helped a bunch. They can be picked up at TSC, but I can not find it on there website. Here is a link to one on greens-machine website. The solenoid valves are a nice way to go and many handles are available with buttons incorporated.

Thumb hydraulic Flow restrictor

 

[ptgdigger]

When using an electric solenoid valve that is usually plumbed into another backhoe circuit like boom raise and lower or left right swing, so the effect is splitting that circuit , no button press is normal function , button pressed - thumb function. So even though a solenoid valve has no feathering ability itself you have the feathering ability of the backhoe valve function that you subbed the thumb on.

Usually the thumb is subbed off a function on the left joystick and the right joystick controls bucket curl so you can use the thumb and bucket like "pincers" without removing your hands from the sticks. Plumbed this way you also retain the protection of the main relief on the backhoe valve , also some backhoes use cushioned or restricted swing circuits which may offer an advantage if you sub off of them "beyond" the restrictor or cushion valve.


Ray

 

[CDN Farm Boy]

When using an electric solenoid valve that is usually plumbed into another backhoe circuit like boom raise and lower or left right swing, so the effect is splitting that circuit , no button press is normal function , button pressed - thumb function. So even though a solenoid valve has no feathering ability itself you have the feathering ability of the backhoe valve function that you subbed the thumb on.

What he said

 

[jim_wilson]

Unfortunately lately I've been massively side-tracked by other projects - but I'm still actively (slowly) -pursuing this.

I got some of the parts in a week or so ago for one of the initial modifications I'm going to make - which is to add a Stucchi block in for the hydraulic connections to the back of the tractor. We're getting a ton of rain this week - so maybe I'll have the time to mock up the brackets I need to get this mounted so I can get something off to the plasma cutting service.

 

[Gundawg]

I am new here and I recently found this thread by doing a search. I recently bought a B3300SU with a BH77 backhoe and loader I got the factory mechanical thumb and I plan to convert the thumb to hydraulic operation. I have been weighing out the options of how to do this. I have some experience with hydraulic system as a forklift mechanic years ago but my experience is in repair and not design. My first thought were to T into the pressure and return lines with a double acting open center electric solenoid type valve relying on the existing bypass valve but I am not sure this will work. The cylinder and hoses for me is the easy part plumbing it correctly is what I need to research better.

I have posted on several forums about doing this and have done many searches on the subject. The best thread I have found is this one and the one on here with the link posted earlier by the guy who did a DYI conversion on the BX25. One of the methods suggested using a diverter valve and I am considering doing that but I would rather keep all other hydraulic operation while operating the thumb my plan was to mount a switch to operate the thumb on the bucket curl lever.

Mike