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Hydraulic Controlled Joystick Issue - Left - Boom/Arm Slow

Discussion in 'Excavators' started by CSS, Jan 20, 2022.

  1. CSS

    CSS New Member

    Joined:
    Apr 28, 2020
    Messages:
    2
    Location:
    Brisbane, Australia
    Hi,
    I have searched for a few hours to find possible causes/fixes for my issue, however I thought I would ask the experts first before I start my trouble-shooting on an old excavator I have bought for farm use.
    Machine - 2002 Thomas (NAGANO) TS45-S 4.5 Tonne Excavator, Isuzu motor and Nachi hydraulics. 7500Hrs. (boom, arm and bucket cylinders are good)
    Issue: Left Joystick ARM/Boom (Forward <--> Back) weak hydraulics - slow to move. All other hydraulics operate as they should. Switching the joystick controls from ISO to SAE moves the problem from the ARM to the Boom, so I think the issue (low pressure) is in the Pilot line/circuit which goes through the left joystick.

    I am thinking I'll test in this order to find the cause:
    1. Measure the pilot pump output pressure first and adjust if needed,
    2. Measure the pressure coming out of the joystick,
    3. Clean the strainer in the pilot line that goes into the joysticks to check,
    4. Test the joystick itself ie weak internal springs by swapping the joysticks over to test. (my parts book says the joysticks are the same part number)
    5. Change all the hyraulic fluid and filters, or should I do this first?

    Am I on the right track, let me know your thoughts, advice etc. thanks in advance

    Cheers.
     
    funwithfuel likes this.
  2. uffex

    uffex Senior Member

    Joined:
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    Location:
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    Good day
    No1 low pressure would effect all circuits otherwise you are right on track, compliments on the diagnostics.
    Kind regards
    Uffex
     
    funwithfuel likes this.
  3. funwithfuel

    funwithfuel Senior Member

    Joined:
    Mar 7, 2017
    Messages:
    4,329
    Occupation:
    Mechanic
    Location:
    Will county Illinois
    #3 would be my guess. Going one step further, I would check the hose from your pilot manifold to the RCV to make sure you don't have a flapper on the inside. I believe, on most equipment, the pattern change valve is after the RCVs soI don't think your issue is further down the line.
    #2 the pressure only matters if you're Teed into the pilot out. Don't deadhead into a gauge, that will yield false information.
    Good luck and be careful
     
    mg2361 and uffex like this.
  4. Coy Lancaster

    Coy Lancaster Senior Member

    Joined:
    Dec 19, 2014
    Messages:
    1,624
    Occupation:
    service tech
    Location:
    Arkansas
    If like you say the problem is in just that one function of the joystick I would also check for a collapsed or pinched line.
     
  5. uffex

    uffex Senior Member

    Joined:
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    Occupation:
    Admin
    Location:
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    Good day
    You may find the attached helpful.
    Kind regards
    Uffex
     

    Attached Files:

    Coy Lancaster likes this.
  6. CSS

    CSS New Member

    Joined:
    Apr 28, 2020
    Messages:
    2
    Location:
    Brisbane, Australia
    Thanks all for the advice, it's appreciated. I'll be investigating it at the end of the week hopefully, and will update accordingly.
    Cheers.
    Chris