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Cat 311 Broken Thumb

Mike007 · 2019-08-04 20:44

Hi, while using my 1996 Cat 311 today with hydraulic thumb, moved a small log and shortly thereafter the thumb won’t close/retract. Didn’t jam or hit anything. If I push thumb closed with the bucket it falls back open. The open function seems to still operate fine. Trying to operate the closed function there is slight movement and then nothing. Seems like it is trying to move fluid as hose flexes. Any ideas? Thanks

Replies4
  1. #1Theweldor2019-08-04 21:46

    I would check the hydraulic cylinder first. Sounds like the piston came loose.

  2. #2Mike0072019-08-04 22:17

    Thanks what is the best way to check this

  3. #3uffex2019-08-05 01:41

    Good day If you plug the lines with gauges and get full pressure when you operate the thumb then for sure your issue is in the cylinder. Kind regards Uffex

  4. #4Mike0072019-08-18 19:03

    Ended up being, I don’t know what.. There was a bolt loose on the cylinder (bolt that secures the cylinder) and I cleaned about an inch and a half of dirt out from under the floor mat. I don’t think the dirt was the issue, not sure about the bolt.