Custom hydraulic backhoe thumb

[slicktierney]

Dave;
I called valve mfg direct, they had no problem shipping one to me. I emailed for a quote first, they are in Ct.

 

[dfkrug]

I called valve mfg direct, they had no problem shipping one to me. I emailed for a quote first, they are in Ct.

Direct from Hydraforce?! That's great news! They told me I had to go to
one of their distis. I would MUCH prefer to go manuf-direct. What did you
pay for this valve, assuming you used the same one I did?

 

[dfkrug]

How is everything holding up? Are the function and use as designed working just as you thought?

It has worked so well that I used the same approach (and same valve) on
my 4-in-1 bucket. Notice that there are very few added hoses....I just
hate to snag hoses.

As for wear and breakdown....lets just say that I am glad I went to 1 inch
pins (I used 3/4" in my prototype). Many times I grab a rock and it breaks
in half, due to the pressure and the sharp hard "rock share" thumb tip I
used.

Thx, Rob!

 

[slicktierney]

I first emailed them for a price quote. They told me $45. +shipping and 3 weeks to get it. I called the guy tues 24th and he said they would make it from parts and send it much sooner. I'm in no rush anyways, thats 3 projects away.

 

[slicktierney]

Dave;
Pm'd you for 25 mm pin p/n's Thanks

 

[bumperm]

This is an old thread, but I have a newer tractor, and one with a mechanical thumb on a BH77. Giving Dave credit, I shamelessly copied his idea on paralleling the curl cylinder. Works great! (thanks Dave). Here's some pictures and notes:



I used this 2 X 20 cylinder as it has adjustable port positions which I thought good in this app. http://www.baileynet.com/product/19560



Close up of Hydraforce solenoid valve. Had to special order from one of their distributors - they wouldn't sell direct. I had to use two fittings to attach it to cylinder as the SAE 8 to 6 90* was out of stock - When I get it, I'll remount and also install a bracket for the valve - it is probably sturdy enough if you don't bonk it.





Taken before wiring Solenoid.



I wanted the waterproof push button switch on the joystick. Switch from Amazon, aluminum bracket from my little machine shop.



Finished switch install, shrink wrap on joystick shaft to keep it clean.



I used a Powerlet jack and plug (also referred to as Bosch or BMW plugs - and may be still sold by JD dealers) to plug into the tractor's 12VDC. One neat "happy" was that Kubota, on the B50 series, supplies a wired plug end at the left rear of the tractor AND the plug is a match for the Powerlet waterproof outlet - - how cool is that?!

http://www.powerlet.com/shop-by-product/plugs-sockets-wire-more/PWRDIST



One little "oops" occurred at the rod end of the cylinder. I needed about .360 more width, so made two .180" spacers. However, once installed, the ram end didn't end up on the pin centered - - took both spacers on one side (shown) to fit up nicely - guess this is due to a slight misalignment on the dipper stick bracket from the factory.

There was probably enough slack between the 25mm pins and the 1 inch cylinder end holes so the ram would have centered, but I used .012" brass shim stock to make bushings which took most all the slop out.

Tested it picking up a big rock - works great! And no more having to get off the tractor to deploy or put away the thumb.

bumper

 

[dfkrug]

This is an old thread, but I have a newer tractor, and one with a mechanical thumb
on a BH77. Giving Dave credit, I shamelessly copied his idea on paralleling the curl cylinder. Works great!

Nice pix, BUMP.

I don't know why a lot more folks don't do it this way. I posted primarily to show another way to do it, and for
people to copy at will.

Let's see what kind of protection you add to the valve. That is certainly a vulnerablity. Mine has never been
hit, fortunately.

 

[bumperm]

The 2 X 20 cylinder I used, while having the correct stroke (10") for my app, is overall about 2" too short on the BH77, which has a welded on bracket for the manual thumb. i.e. with thumb fully retracted there's a couple of inches or rod still extended. And with ram extended fully, thumb is extended, certainly a usable amount, but not quite all the way (probably could go another 2". Works, but it could be better.

So, when I get the time, I plan to saw off the upper cylinder tube and weld in a spacer. It'll also give me the opportunity to correct the ram positioning issue (both spacers now on one side of ram as upper bracket is apparently not quite square with dipper). I'll weld the spacer to the cylinder first, then tack weld the spacer to its tube with cylinder mounted on the hoe - so I can get the alignment right.

bumper

 

[MEA]

The 2 X 20 cylinder I used, while having the correct stroke (10") for my app, is overall about 2" too short on the BH77, which has a welded on bracket for the manual thumb. i.e. with thumb fully retracted there's a couple of inches or rod still extended. And with ram extended fully, thumb is extended, certainly a usable amount, but not quite all the way (probably could go another 2". Works, but it could be better.

So, when I get the time, I plan to saw off the upper cylinder tube and weld in a spacer. It'll also give me the opportunity to correct the ram positioning issue (both spacers now on one side of ram as upper bracket is apparently not quite square with dipper). I'll weld the spacer to the cylinder first, then tack weld the spacer to its tube with cylinder mounted on the hoe - so I can get the alignment right.

bumper

Bumper-

I have a new BH77 and I am following your build here. Would you mind sharing the part number and supplier of that switch and valve? I will search amazon for the switch once you narrow it down for me and I'm not sure where you ended up getting the valve. Feel free to ping me directly if you would rather. I can't thank you and Dave enough for sharing this set up.
-MEA

 

[bumperm]

MEA,

The valve is a Hydraforce SV08-24-6T-N-12DS

As mentioned earlier, I tried to order direct from Hydraforce, but no joy. They referred me to one of their dealers Hydraulic Controls in the S.F. Bay area 510-658-8300, who referred me to their branch in Yuba City, CA (closer to me). Called them and it wasn't in stock, 3 week wait and I flew over to Sutter County airport and they met me there with the parts!

Hydraulic Controls, I think, has outlets all over, so you might could find one close to you.

I used two 3/8 JIC female 1/4 inch hoses, one 24" and one 18" (stock lengths) from surpluscenter.com/Hydraulics/

I bought all the hydraulic fittings from Discount Hydraulic Hose

One particular part, the SAE 8 O-ring to SAE 6 O-ring 90 degree, I could only find at discount hydraulic hose:

O-Ring Boss (ORB) Union 90° Elbow part 6807-08-06

This goes from the cylinder (assuming you use the same one I am using, as it has SAE 8 O-ring flush ports) and the hydraforce valve has SAE6 ports. This fitting allows the valve to fit nice and snug (snugger than what I've shown in my pics - as this particular fitting was out of stock so I used two fittings to "get there"). I have the right one now and will install it when I lengthen my cylinder a little. (OCD . . . the cylinder works as is, I just can't leave good enough alone - it's a sickness :c).

BTW, you will be replacing the 3/8 JIC male to 1/4 NPT 90's on the BH77 cylinder with street T's 3/8 JIC 1/4 NPT

Plumbing is a piece of cake.

Oh, the switch I used is this'n: Amazon.com: Alpinetech 19mm 3/4" Waterproof Momentary Stainless Steel Metal Push Button Switch Screw Terminal Extended Button Normally Open 1NO: Automotive

bumper