Guidance needed. Mech thumb to hyd thumb

   / Guidance needed. Mech thumb to hyd thumb #1  
I

IXLR8

Veteran Member
Joined
Aug 21, 2007
Messages
2,025
Location
Eastern Shore- Virginia
Tractor
Kioti DK-40SE
Hi folks,
I have a mechanical thumb on my BH, I am getting tired of moving it between mounting pins for the different things I am doing with it. I also think it was welded on too far from the bucket and it would pick up better if it was closer. Sooo I was thinking about converting it to a hydraulic thumb. Biggest question is how big a hydraulic cylinder I should get. My concern is if I get one with too small of a shaft.. I could bend it with the force of the bucket. I have worked out most of the other issues, pin size, cylinder length and throw, just not sure on sizes of piston and shafts. I was thinking of getting a cylinder like the C&C top links with the valving to lock it in place. I have an extra rear remote that I could use to drive it. Still sorting out control valving... so any suggestions would be appreciated.

TIA
 
   / Guidance needed. Mech thumb to hyd thumb #2  
A 2-1/2" to 3" dia should give all the clamping pressure you would ever need. Find out what pressure you need then look for a cyl that has the largest dia rod.
 
   / Guidance needed. Mech thumb to hyd thumb #3  
Without knowing what brand of thumb you have, or seeing pictures of it-it's going to be real hard to recommend anything specific. Pictures and measurements of the stationary link would be very helpful
 
   / Guidance needed. Mech thumb to hyd thumb
  • Thread Starter
#4  
   / Guidance needed. Mech thumb to hyd thumb #5  
Are you wanting it mainly for repositioning or will you be actually using it to close against the bucket?
Main difference is that if it's for repositioning, you could go with a stout cylinder and rod since it will act like a regular thumb...like a backstop and using a DPOCV is a good idea for that.
If you're going to use it to close onto the bucket, I'd be sure it was no stronger than the hoe cylinder.
 
   / Guidance needed. Mech thumb to hyd thumb #6  
theoretically if all the pivot points were equal in the both of them then the same size as your bucket cylinder would work

tommu
 
   / Guidance needed. Mech thumb to hyd thumb
  • Thread Starter
#7  
3RRL said:
Are you wanting it mainly for repositioning or will you be actually using it to close against the bucket?
Click to expand...
Mainly for repositioning. I have only used it a few times... already tired of getting on and off the tractor to position it where I want it... or get it out of the way. Guess I am getting lazy in my old age... or just figure since I have the hydraulics available... why not use them. :)
 
   / Guidance needed. Mech thumb to hyd thumb #8  
IXLR8 said:
Mainly for repositioning. I have only used it a few times... already tired of getting on and off the tractor to position it where I want it... or get it out of the way. Guess I am getting lazy in my old age... or just figure since I have the hydraulics available... why not use them. :)
Click to expand...

There is a fine line between lazy and efficient.

Check out my post that I just completed tonight. My thumb cyl has a
1 1/16" rod, while my bkt cyl is 1.25. I don't like the separate spool
valve controls I have seen for thumbs, so I elected to use a solenoid
valve on one side of the thumb cyl.

http://www.tractorbynet.com/forums/showthread.php?p=1450192#post1450192
 
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