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Cat 336 delayed response

Discussion in 'Excavators' started by tbone1471, Mar 29, 2022.

  1. tbone1471

    tbone1471 Well-Known Member

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    Location:
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    Cat 335fl
    Rkb10639

    When using the controls it seems like the hydraulics have a delayed response. It is the same when letting go of the joystick. The machine takes about 1 or 2 seconds to stop functioning.

    it makes it very difficult for delicate work.
    For example if I pull the control back to raise the boom it will linger for a second then start to raise. If I let off the boom may go up a few more inches. Any suggestions as to what may be the cause?
     
  2. aongheas.macask

    aongheas.macask Well-Known Member

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    Air in your Servo system most likely
     
  3. tbone1471

    tbone1471 Well-Known Member

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    Do you have a repair or inspection procedure available?
     
  4. tbone1471

    tbone1471 Well-Known Member

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    Any suggestions? This is driving me crazy
     
  5. uffex

    uffex Senior Member

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    Good day
    That suggests the RCV (Control lever) is taking its time to drain> possible cause blocked case drain filter or to heavy grade of hydraulic fluid.
    Kind regards
    Uffex
     
  6. tbone1471

    tbone1471 Well-Known Member

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    I thought these controls were electric over hydraulic? I'm would assume there is still a pilot system but it is controlled by solenoids not the joysticks directly?
     
  7. uffex

    uffex Senior Member

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    I have not checked if you have a hydraulic schematic, that will reveal which you have. You are correct if it has electric over hydraulic the same situation would apply
    KR
    Uffex
     
  8. uffex

    uffex Senior Member

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    In the spec. I have fails to mention other than "Electronic control of the main block" maybe Nige has the information.
    KR
    Uffex
     
  9. DEMLONE70

    DEMLONE70 Senior Member

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    Its pilot operated
    With a patern changer
     
  10. tbone1471

    tbone1471 Well-Known Member

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    I think that machine does have a pattern changer. But the controls are electric over hydraulic. So no pilot lines in the cab.
     
  11. DEMLONE70

    DEMLONE70 Senior Member

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    Its pilot operated for boom and stick
    Aux circuit its electric
     
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  12. DEMLONE70

    DEMLONE70 Senior Member

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    336.png
     
    uffex likes this.
  13. tbone1471

    tbone1471 Well-Known Member

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    I will have to get a look at the machine later this week. But I thought all the controls on the f series were electric pilot?
     
  14. Vetech63

    Vetech63 Senior Member

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    I'm not sure on your machine but in some there is an inline filter on the return circuit of the pilot system. I would start there if you have it. Slow nuetraling response is usually a restricted return circuit in the pilot hydraulics
     
    BigWrench55 and mg2361 like this.
  15. DEMLONE70

    DEMLONE70 Senior Member

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    F series are pilot
    Nex Gen are electric
     
  16. tbone1471

    tbone1471 Well-Known Member

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    Is anyone able to supply a hydraulic diagram so we can check for the filter?
     
  17. Nige

    Nige Senior Member

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    This is the setup of the pilot lines for the 4 main functions (not Aux) plus travel in the cab for your Serial Number. They go straight to the joysticks/foot pedals with no electrics in between.

    upload_2022-4-5_16-54-30.png
     
  18. Nige

    Nige Senior Member

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    Attached procedure for changing the implement pilot filter. Element P/N is 5I-8670.

    The pilot system on this machine has an accumulator. Has anyone checked that it is functioning correctly.? It is quite simple to do, see Steps 1 thru 5 of the "Preliminary test Procedure on Pages 2/3.
     

    Attached Files:

  19. John C.

    John C. Senior Member

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    Unless this is something different, the accumulator is used to lower the boom or stick if the engine is dead. It shouldn't have anything to do with the delay. It used to be one of my inspection checks but I found so many flat ones that I quit checking them.
     
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