You guys are confusing me. All the backhoe thumbs I know about do
not use hydraulics, they are just a fixed "fork". You curl the
bucket to shove a rock or stump into the thumb so it doesn't
continue to fall out of the bucket.


(top posted for your convenience)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Keep the whole world singing . . . .
DanG (remove the sevens)




"Shawn" shawn_75ATcomcastDOTnet wrote in message
...

"Eric R Snow" wrote in message
...
I need to make a thumb for the 580CK Case tractor backhoe.
The bucket on the front of the machine will keep the same angle
as it
is raised and lowered. So, for example, if the operator tilts
the
bucket to a ten degree angle with one lever it will keep that
angle as
the bucket is raised or lowered with the other lever. I want to
plumb
the thumb to work the same way. It appears to me that it may be
valving that makes the front bucket behave this way. Anybody
know how
this is done?
Thanks,
Eric R Snow

If this is the machine I am thinking of, there is a level
compensating slave
cylinder on the right side of the machine. This adds or
subtracts fluid
from the bucket tilt cylinder as appropriate. The hoses to this
cylinder
don't go back to the valve body, just across the bucket tilt
lines. It is a
fairly common method to accomplish this action.

Shawn