Thumb Converting Woods BH90x thumb from mechanical to hydraulic

[IslandTractor]

This will start a new thread on the topic.

A couple of weeks ago I was chatting with another TBN member Charlesaf3 about the Woods BH and he commented that it might be possible to convert the factory mechanical thumb to hydraulic as most of the hardware and weldments were identical. For those who have not priced factory thumbs from Woods, there is about a $1200-1500 price differential or something close to that between the mechanical and hydraulic factory thumbs. If, as suspected, the only real differences are 1) a hydraulic cylinder, 2) hydraulic lines and fittings and 3) a control valve, then it should be fairly easy to convert the mechanical thumb to hydraulic. I will be looking into this over the fall and am starting the thread over so that others can offer insights, warnings etc as well a perhaps do the same thing.

By way of background, it is pretty clear that the thumb itself is identical in both factory versions. The weldments and bushings on the bucket arm are also pretty clearly the same. The mechanical thumb is controlled by a simple tube within a tube lengthening rod. The hydraulic thumb version appears to simply replace that mechanical lengthening device with a standard hydraulic cylinder (anyone know the exact size???) along with appropriate lines and control valve. If I recall correctly it draws power from the left stabilizer circuit.

The hydraulic lines are nicely led back to the operator station in the factory version and control of the thumb is via a foot operated "treadle" switch. Of note the operator station on the standard BH and the mechanical thumb version have the cut outs on the left foot platform for this treadle controlled valve. I have not seen such a treadle controlled or foot controlled valve in my perusing of the Surplus Supply site so I was thinking of just using a standard two way spool valve and mounting it someplace convenient near the other BH controls. I learned today however that dfkrug used an electric over hydraulic valve set up on the thumb he installed so there are other options for controls than what Woods offers. It would be nice to find a source for the Woods supplied valve. I imagine if no primary source is found that Woods would be able to supply that as a repair/replacement item.

Bottom line at the paper planning stage is that it appears possible to convert the factory mechanical to a hydraulic thumb for considerably less than $400-500 (guessing $100-150 for cylinder, $50-150 for hoses/fittings and ?$100 for a control valve). I would be interested in doing that.

Let's use this thread to explore options, costs and issues.

[nickel plate]

I don't know if the manufactured year will make any difference but I am willing to supply any measurements you may need from my BH90-X w/hydraulic thumb. The only problem with that may be if the unit needs to be attached to the tractor for full open/full close measurements so I would hope a few other BH90-X owners would also be available if the need arises.
Woods has an installation manual for the hydraulic thumb on a tractor mounted BH90-X. The manual number is 1020085 and is also designated MAN540 (Rev. 12/14/2007) and is more than likely available in PDF on the Woods website.

[Charles Billings]

Yes, the manual is available in pdf. Go to http://www.woodsequipment.com/WorkAr...nt.aspx?id=185. The hydraulic cylinder is a 2.5 x 1.5 x 16.75.

[J_J]

Why not use an electric valve, and put the toggle switch on the hand control. You don't need any feathering action, as the bucket will provide that. All I see, is an electric valve, cylinder, and switch, and of course hose and wire. Go for it.

[Charlesaf3]

obviously I think it makes sense On the hydro cylinder, I'd measure the pin diameters, and the cylinder length with the thumb at both extreme positions, and then look for a cylinder that came close. Seems like a pretty standard sizing.

One possible issue is that on hydraulic thumbs that are built in, thumb relief is set lower than bucket relief. I wouldn't worry too much about that personally, but not having different reliefs probably increases the chance of bending the thumb cylinder rod. Maybe that could be finessed by using a thicker rod?

I was going to do something similar on my bh80, though I was just going to run the hoses to my remote on the 3030. Unfortunately, the remotes on the kioti are a bit awkward to run from a backhoe seat, but still might be able to use them with an intermediate control of some sort

[kennyd]

I think I would would use a electric diverter on one of the stabilizer circuits if I where doing it. Seems simpler than adding a new spool valve and having to plumb into the main supply/return lines.

[IslandTractor]

The electric diverter option does seem to be the simpliest way to go at this point. I'll check out surplus supply.

The Woods installation manual pretty much confirms most of my assumptions regarding how to do the conversion. The main decision seems to be the valve. I do like the Woods foot control but that would be difficult to duplicate given the custom hardware involved.

[kennyd]

The 9-5117-A would be a great choice.

[Charlesaf3]

foot control is nice, but I don't think its a big deal. I rarely, if ever, move both hands and the thumb at the same time - I'd have no hesitation mounting a simple lever control or the like

[ElDorado]

Guys, you are way ahead of me. I am thinking about a BH80 with a thumb. I was appauled that Woods would price the hydraulic thumb so much more than the mechanical version. I am able to rationalize the mechanical version but there is NO way I can rationalize the price they are talking for the hydraulic. This also got me thinking about getting the mechanical and then converting to hydraulic myself.

So has any more developed on this issue? Any "kit" that is available or list of parts and suppliers?

Matt