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CAT 307 boom crashes to the ground

Discussion in 'Excavators' started by CJLennon, Jul 21, 2011.

  1. CJLennon

    CJLennon Well-Known Member

    Joined:
    Jul 24, 2009
    Messages:
    62
    Location:
    Chapel Hill, NC
    Hey Folks,
    Let me start this post like I do all my other ones. Thanks to all for making me look smart in front of the boss! I have a grey market CAT 307 excavator who's hydraulics work great except for one thing. When you lower the boom, it drops in one speed only - FAST! When you lower the boom, it comes crashing to the ground with no resistance. Has any one ever experienced this on any CAT machine? Some one told me that there is a valve called a drift reduction valve that could have a problem. Did any one ever hear of this valve? If so, can you tell me where it is in the valve body? I've got a parts book for this machine but not a service manual.
    As always, thank for the education!:notworthy

    Chris
     
  2. Per Eriksson

    Per Eriksson Senior Member

    Joined:
    Oct 24, 2007
    Messages:
    643
    Location:
    Sweden
    It could be the pilot control valve that sticks or have a broken spring, try shifting the boom outputs with the bucket and see if it still freefall or measure the pilot pressure from it so it follows the movement of the joystick smoothly.
     
  3. CJLennon

    CJLennon Well-Known Member

    Joined:
    Jul 24, 2009
    Messages:
    62
    Location:
    Chapel Hill, NC
    Eriksson, thanks for the quick reply and the insight. Sounds like a good plan and we'll give it a go this weekend. Appreciate the help!

    Chris