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CAT 130G 9Y Series Transmission Won't Shift

Discussion in 'Motor Graders' started by andy.jobcorps, Apr 25, 2018.

  1. andy.jobcorps

    andy.jobcorps Member

    Joined:
    Apr 24, 2018
    Messages:
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    Location:
    White Swan, WA
    Hello all, I've got a 1978 CAT 130G 9Y series grader with the 3304 engine that will not shift into either forward or reverse at any speed. Main Hydraulics work fine. So far I have checked:
    Transmission Oil - Full
    Transmission Filter - Replaced
    Transmission pump pressure - low 250 PSI, added another spacer to relief valve group, now 300 psi
    Shift cable - connected at both ends
    Manual Modulation Cable - connected at both ends
    Forward/Reverse Cable - connected at both ends

    Any ideas you have would be appreciated. Thanks.
     
  2. r20d12

    r20d12 Well-Known Member

    Joined:
    Nov 29, 2009
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    Occupation:
    heavy equipment field tech
    Location:
    oklahoma
    If the modulation pedal is malfunctioning. It will not let clutches engage. Make sure everything moves free. Actually take the cable loose on both ends and slide it back and forth by hand and make sure pedal is all the way up. Then check clutch pressures.

    Hope this helps
     
  3. Nige

    Nige Senior Member

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    Did you take a look inside the old filter or in the suction screen to see if there were any clutch material paritcles in there..?
     
  4. 20/80

    20/80 Well-Known Member

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    nova scotia canada
    What were you doing when you lost your gears? did this happen while grading or working your machine? or was the machine sitting for awhile and now your gears don't work?
     
  5. andy.jobcorps

    andy.jobcorps Member

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    Location:
    White Swan, WA
    Operator reported that it came to stop on its own while grading, put it in reverse where it sluggishly rolled a bit then was dead in the water.
     
  6. r20d12

    r20d12 Well-Known Member

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    Location:
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    Sounds like you need to check pressures and then inspect the magnetic screen.
     
  7. andy.jobcorps

    andy.jobcorps Member

    Joined:
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    Messages:
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    Location:
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    Ok, we think we figured it out. it appears the pilot pressure tap plug at the top of the XMSN valve bank fell out in operation and is allowing the pressure to dump out of the valve.

    Troubleshooting steps to date:
    -Oil level checked - full
    -XMSN Filter changed - old filter relatively clean
    -checked all pressure taps except pilot pressure tap (difficult to access)
    -Pressures - see table
    -drained oil and dragged a magnet through it - clean
    -the tap P2 for the direction clutch was 0 psi when it should have been approx. 200-250 psi (our pressure gauges had 30 psi error) that led us to valve level three to check the differential, safety and check valve - everything was fine
    -since we had it out we disassembled and inspected the entire valve bank. - everything was fine
    -at this point we were running out of easy checks and took another look at the book. forgot to check the debris screens.
    -bottom debris screen had the plug for the pilot tap in it as shown in pics below - should have checked debris screen first.

    it also looks like the speed clutch is starting to wear out as there were a number of bronze flakes in the screen as well.
    We're still putting it back together and have yet to test it; should know tomorrow. Thanks for the help everyone.
    130G XMSN Pressure Readings.JPG
    IMG_5975[1].JPG IMG_5976[1].JPG IMG_5977[1].JPG
     
  8. Nige

    Nige Senior Member

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    Can you post some better photos of the brass particles that came out of the magnetic screen..?
     
  9. andy.jobcorps

    andy.jobcorps Member

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    Location:
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    The plug fixed the problem! It moves in all gears and directions.
     
  10. andy.jobcorps

    andy.jobcorps Member

    Joined:
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    Location:
    White Swan, WA
    Here you go.
    IMG_5984[1].JPG IMG_5991[1].JPG
     
  11. Nige

    Nige Senior Member

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    The dark pieces appear to be clutch material. Not sure about the source of the brass ones though. Could even be differential. Just to be clear, on this machine there are two identical screens, one (upper) for the differential & bevel gear compartment, the other (lower) for the transmission. Which of the two did these particles come from..?

    Maybe run the machine for a while and pull the screens again to see what has accumulated.
     
    Last edited: Jun 14, 2018 at 8:09 PM
  12. d9gdon

    d9gdon Senior Member

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    central texas
    That's great. I can never get that lucky on a breakdown!