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140m sluggish(hesitating) lift

Discussion in 'Motor Graders' started by JOHN140, Mar 24, 2020.

  1. JOHN140

    JOHN140 Active Member

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    Hello all. Need some help with a problem on 140m b9d1908. Lift functions hesitate and don’t seem consistent anymore. I’ve noticed if I hold the ripper switch open while operating lift works perfectly. Do u guys know what would cause this. Thanks for any help.
     
  2. Paul Council

    Paul Council Senior Member

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    Sounds like resolver issues.
     
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  3. Nige

    Nige Senior Member

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    Classic symptoms.
     
  4. Mark250

    Mark250 Senior Member

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    Hi, As above but I would check for the latest software first and calibrate the controls
    but also check the resolver balls and seats and the lift valve compensator spools especially the seats as they pond out and I have had to get them repaired

    upload_2020-3-25_20-58-57.png
    upload_2020-3-25_21-5-29.png
     
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  5. Nige

    Nige Senior Member

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    Good point on software by Mark.
    Please post up what is in every ECM in the machine right now. I recall at one time software upgrades on early M-Series were made multiple times a yesr. This machine B9D01902 came from that same era, built December 2008. I was working with early 16M B9H-prefix machines at that same time period - same comments apply.
     
  6. JOHN140

    JOHN140 Active Member

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    Thanks guys. I’ll check all that out and let u know.
     
  7. JOHN140

    JOHN140 Active Member

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    About the compensator spoils and resolved balls. Is there a way to pinpoint the faulty valve or could it be any of them?
     
  8. JOHN140

    JOHN140 Active Member

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    Software is all the latest versions. Cat updated everything thing a couple of months ago when we had a new turbo put on it.
     
  9. 92U 3406

    92U 3406 Senior Member

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    I'd look at a schematic and follow the oil flow in the resolver network. Depending on which functions you cycle along with the lift circuit, you can control the position of the resolvers and that will allow you to pinpoint which resolver is sticky or leaking.
     
  10. Nige

    Nige Senior Member

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    Did Cat do all the calibrations in the hydraulic system at the same time..?
    Also did they leave you a copy of the Product Status Report.? If not can they supply one.? For your machine it'll be an Adobe pdf file of about 20 pages.
    You could then post it up here and we could take a look at what it has, along with all the Diagnostic issues it had generated.

    Here's a curve ball from left field. Did it start playing up right after the turbo was replaced and the software updated..?
     
  11. Nige

    Nige Senior Member

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    IIRC the latest software versions allow for programmable changes for different grades/viscosities of hydraulic oil.
    I wonder if what's programmed into the Config screen is the same grade as what the customer is actually using.? Again, a PSR would tell the tale.
     
  12. Mark250

    Mark250 Senior Member

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    hi this block diaghram doesn't show the ripper however the ripper section is usually before the articulation section and then the lift sections

    upload_2020-3-26_7-59-32.png

    upload_2020-3-26_8-15-19.png
    upload_2020-3-26_8-16-20.png
     
    Last edited: Mar 25, 2020
  13. Mark250

    Mark250 Senior Member

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    The signal circuit is a parallel control circuit that allows the highest load signal to up stroke the pump
    A signal (resolver valve) valve that is leaking will stop or slow the pump upstroke. Because the valves are in parallel. all the functions will be affected to some degree.
    To test it is best to operate and hold the function that is not working correctly and then in turn operate all other functions and see if one function makes a difference. That is usually the problem valve
    If it is only the lift functions affected I would suggest that the lift compensators valves and or there seats are suspect
    Also don't forget to operate the steering as it also has a resolver valve and has been updated quite often over time

    upload_2020-3-26_8-18-33.png
     
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  14. Mark250

    Mark250 Senior Member

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    In the early days there were a few problems with these valves and they were updated
     

    Attached Files:

  15. JOHN140

    JOHN140 Active Member

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    Thanks for all the help. I’ve been really busy on a Txdot job and not much time to be on here. We are going to get into this pretty soon and will let you guys know what I find out.
     
  16. JOHN140

    JOHN140 Active Member

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    When it comes to showing cat this problem and getting it fixed. Do you agree it shouldn’t make any difference in the response of the lift cylinders whether I’m using the ripper function or not. In other words the lift response should be the same regardless. Right?
     
  17. JOHN140

    JOHN140 Active Member

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    What would be the best way to show them this problem so they can get it fixed. A lot of the time the mechanics seem like they are clueless as to how a machine is supposed to operate. Some have the opinion if it moves that means nothing is wrong with it.
     
  18. Nige

    Nige Senior Member

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    No, it should not. In fact the opposite should be true. If you try to use multiple functions (like lift and ripper) at the same time the active functions should all slow down, not speed up. Reason - only a certain amount of oil flow coming from the pump. If you spilt the available flow from the pump between various functions each one of them has to move slower. Basic physics.
    Show them how the lift function works when used on its own.
    Then show them what happens if you operate the ripper and the lift at the same time.
    Then look them in the eye - "This can't be right, right...?"

    While you're still down see if you can't get a copy of the PSR from when the dealer came out to it before.
     
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