BH77 Hydraulic Thumb

[Reddivrbob]

I'm looking to add a hydraulic thumb to my BH77 on my L3301. Any kits out there? Or suggestions on Fabrication components? Cylinders, valves, switches, etc.?
I don't want to do any welding on the booms, so would like to use existing mounting for cylinder. I have installed 2 remotes for Top & Tilt, so hydraulics are already there.

 

[Chanceywd]

I made my own system using this cylinder, https://www.ebay.com/itm/232166517902 because of length etc.
But I see it is back ordered now seeing where they come from it is no surprise.

I teed my summit 3rd funtion grapple outputs to the back and teed switch to make it work with a switch from surplus center. Also put a relief valve back to tank on the base side of cylinder out of caution of not wanting to overpower the hydraulic circuit in the valve with the bh77 bucket curl.

It has worked quite well. I can add some more info and pictures if you are interested.

Bill

 

[Reddivrbob]

I made my own system using this cylinder, https://www.ebay.com/itm/232166517902 because of length etc.
But I see it is back ordered now seeing where they come from it is no surprise.

I teed my summit 3rd funtion grapple outputs to the back and teed switch to make it work with a switch from surplus center. Also put a relief valve back to tank on the base side of cylinder out of caution of not wanting to overpower the hydraulic circuit in the valve with the bh77 bucket curl.

It has worked quite well. I can add some more info and pictures if you are interested.

Bill

I would appreciate any pics and other parts links.
Thanks

 

[Chanceywd]

Well to start with I picked that tang style cylinder because of it's dimensions. It is 19" closed and 29" extended with 1" pin holes. The hydraulic ports are on the side so I positioned it with them on the left for me. The rod end is 1-1/2 wide and that fit where my manual thumb linkage was. I put that end in and positioned the base end in line with the mount hole. I see then it was off (as I remember) about 3/8".

I cut a piece of 1" shaft and welded in to plug the base hole. Then I determined where to bore the hole again by holding it up and marking. I bored the hole and then welded on a 1"shaft collar on each side and then milled about an 1/8" off each side so the base end was centered in the dipper arm bracket. This allowed me to tuck the cylinder and thumb as close as possible up to the dipper arm when not using.

As I posted earlier the cylinder I used was the WTG2x10 and it isn't available right now. I did see the WTG2.5x10 is and it looks like it would fit in there too. It might have the thumb down just a little due to the small difference in dia when the thumb is up.

I was able to snake 2, 1/4"hoses thru in the same path as all the other hoses and that wasn't too had considering I did it by myself. I used the NPT 180" from surplus center 916-14180. They were long enough to come thru up by the right fender where I installed the coupling fittings teed from my 3rd function valve.

The switch I paralleled to the 3rd function switch was from surplus center and is 2 NO push buttons with about a 20 cord and magnets on the back. It is PSN=020-M20 11-2201-20 if I have that number right. I figured I wouldn't be using the grapple at the same time as the backhoe. In use I wasn't sure where I would want the switch and found so far it is handy stuck on the right ROPS.

I added the relief valve to the side feeding the base of the thumb cylinder as I said earlier as I was concerned about the backhoe bucket overpowering the 3rd function when pushing back on it. The relief is a Prince RV H4 9-6135-50-H again from surplus center. I made a bracket and installed that under the loader valve and teed the tank port into the loaded valve tank port.

I did add a ball valve in the base end side of the line on the tractor side before the hydraulic coupling so I could lock the thumb up as I find it leaks down sitting or in use. I assume it has to do with the 3rd function valve but that works so I haven't looked further. I got that idea from other threads here about doing that for top and tilt circuits without the locking circuit on the cylinder.

Bill