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Relief Valve For Thumb

Discussion in 'Excavators' started by Danny Steel, Oct 14, 2010.

  1. Danny Steel

    Danny Steel Well-Known Member

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    I would like to fab a thumb for my 3 ton X

    My problem Is understanding where to put the relief valve
    And also what kind of relief valve to use.:beatsme:)

    Thanks
    Danny
     
  2. Harry Dart

    Harry Dart Member

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    I normally fit a 5 port crossline relief valve, teed into the A & B lines, anywhere between the valve and the cylinder. It relieves from port A to B and from B to A. The 5th port goes back to tank, this stops pressure intensification when the cylinder is forced in, and acts as a make-up to stop cavitation when the cylinder is forced out.
     
  3. Danny Steel

    Danny Steel Well-Known Member

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    Sounds like It should be plunbed In near the pump then

    I thought that there could be a valve that got plumbed right at the thumb cyd. ports
     
  4. watglen

    watglen Senior Member

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    My machine already had a aux circuit with the relief valve built in. Perhaps yours is the same.
     
  5. willie59

    willie59 Super Moderator

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    When you say you would like to fab a thumb, I assume your machine already has an auxilliary circuit on the boom? Or are you going to have to add that as well?
     
  6. Danny Steel

    Danny Steel Well-Known Member

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    They tell me up here, That any Kubota mini x That came from the US
    Needs a reliel valve in stalled, The Kubotas bought here In CA, have them built In
     
  7. Danny Steel

    Danny Steel Well-Known Member

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    Correct....It has the 2 pipes with 1/2" plugs In them, on the stick:)
     
  8. Danny Steel

    Danny Steel Well-Known Member

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    Here's my digger:)
     

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  9. willie59

    willie59 Super Moderator

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    On most machines like that, there are ports on the auxilliary control valve to install relief valves, they may just have port plugs installed in the ports which blocks the internal port to tank. If so, simply remove the port plugs and install proper relief valves, that's the easiest fix for your problem. :)
     
  10. Hendrik

    Hendrik Senior Member

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    The auxillary circuit has a relief valve to prevent damage, however it may not be set to the correct pressure for thumb application, which from memory should be 75% of the pressure in the bucket ram.
    BTW that trench is a little crooked:)
     
  11. Harry Dart

    Harry Dart Member

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    Our local and jap imported KX 41/61/72's have all had port reliefs fitted in the auxiliaries, 2500psi down from 3500 main. Put a gauge in one of the pipes and see what you've got.

    2500psi for a thumb sounds about right, as long as the bucket will just push it back.
     
  12. Digger Dan

    Digger Dan Well-Known Member

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    I just put a thumb on my Kubota 2010 model which was plumbed for auxiliary but it did not come with the relief valve fitted, strange IMO...
     
  13. Danny Steel

    Danny Steel Well-Known Member

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    The wind was blowen hard that day...LOL:drinkup

    Guys, where Is tis relief valve located?:beatsme


    One other thing, Not sure If It aplies here but,......... On the Digital panel
    I hear that you can adjust the auxiliary pressure. If that's the case, Why do we need a relief valve?:beatsme
     
  14. Harry Dart

    Harry Dart Member

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    Factory reliefs will be one on either side of the auxiliary spool in the main valve. Follow the hoses back from the boom piping.
    Panel adjustment would probably be for flow, not pressure, but I'm not sure on your model. :beatsme

    What model is yours?, I'll see if I can find a pic
     
    Last edited: Oct 16, 2010
  15. Danny Steel

    Danny Steel Well-Known Member

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    kx71-3:)