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Thread: 955 12A main clutch issue

  1. #1
    Join Date
    Apr 2020
    Location
    Central Illinois
    Posts
    3

    Default 955 12A main clutch issue

    I a new owner of a 955 12a6303 traxcavator. It ran and operated when I hauled it home. I started by changing oils and filters. When I took it out to clear some brush, it worked fine for about 30mins but then i suspect the clutch began slipping. i barely made it back to shop. The main clutch fluid was very milky so i performed a kerosene rinse and replace with T04 SAE 30. It operated okay for a while but began slipping again once warm. I took it back up to shop to start adjustment procedure.

    If i am understanding the procedure, i loosened the two lock nuts and tried turning the adjuster ring with clutch disengaged. It needed some love with a ball peen and bar to move, not much force, just tapping. I was able to move about 1.5" but procedure says 3"? The lever will now no longer travel over center. Did I go too far or slip and hit something I shouldn't have or do I just need to spin it counterclockwise a bit to find the sweet spot? The clutch still works but have to hold the lever.

    After searching some old threads, I suspect the oil pump is not functioning as intended, which is why it fades when warm. I have acquired a service manual and pulling the clutch looks like a chore, while standing on my head. I think i have convinced myself it is not necessary yet and that i should pull the pump and start there. I plan on pulling it tonight so i can figure out what all i need to replace/rebuild. Google searched for the numbers listed in parts book haven't gotten me far so i am hoping local dealer can support this older machine.

    Also, based on my searches, my serial #12A6303 should be 57-58 with D315 and D6 undercarriage?

  2. #2
    Join Date
    Feb 2007
    Location
    Ste-Julie
    Posts
    1,141

    Default 12a

    When you changed the cluch oil did you check the oil suction screen if he was not pluged and when you adjusted the cluch you loosen the lock nut 2 turns and tap on the small plate to be sure it is free on stud and turn the adjusting ring approximatly 3 inchs and retighting the lock nut and you should have 30 lbs on cluch lever

  3. #3
    Join Date
    Apr 2020
    Location
    Central Illinois
    Posts
    3

    Default

    I did not. The oil was changed prior to removing the top cover. I acquired the service manual yesterday and it looks like there are two pickups? one is a tube and the other is around drain plug? I assume one is for splash and the other is to the clutch. I will drain the oil again tonight and see what I can come up with.

    I made sure the tabs were loose but couldn't much movement maybe ~1.5" out of the adjuster. the adjuster is pretty close to flush with the housing and I haven't located any specs but pictures show adjuster out ~1/8" so maybe it is out of adjustment. I will admit that while i was standing on my head, i think the bar slipped and i may have struck one of the pressure plate levers? I am not sure. The lever went from loose/easy pull to about half travel and no "over-center"

    Thanks for taking the time to respond. I will try for some pictures if it doesn't rain much tonight.

  4. #4
    Join Date
    Nov 2006
    Location
    Faunsdale, AL USA
    Posts
    4,393

    Default

    First step is to back the adjustment off until you hit the sweet spot where the clutch lever snaps in properly. It may be that the oil clutch pump and or itís pickup screen have problems that you will want to correct now rather than later, but get the clutch adjusted to the proper snap and test it before you decide itís shot.
    D2-5J's, D6-9U's, D318 and D333 power units, 12E-99E grader, 922B & 944A wheel loaders, D330C generator set, DW20 water tanker and a bunch of Jersey cows to take care of in my spare time

  5. #5
    Join Date
    Apr 2014
    Location
    georgia
    Posts
    171

    Default 955 12A main clutch issue

    Thumper79

    hi i have a cat 933 loader and have just gone threw this exact same issue . if you tap the plate with a 2lb hammer it will loosen the center ring so you can turn it , i also went to far and the clutch leaver would not snap over . i think i moved mine only about 4 inches clockwise .i turned it back counter clockwise until the clutch lever snapped over nicely. be advised the locking clamps are to be torqued to 30 fp so you dont strip out the threads if you need any more info on the procedure you can message me if needed.
    total movement on mine was about 3 inches
    good luck

    Charlie

  6. #6
    Join Date
    Apr 2020
    Location
    Central Illinois
    Posts
    3

    Default

    Thank you all for the feedback. I finally got back to it with the hope that it was I went too far clockwise with my initial adjustment and a plugged oil pickup. First i tried backing it off and checking but no change to the lever pull. I went a total of about four inches counter-clockwise and no change in the the lever. I have read the procedure a number of times and I swear I am doing what is stated. I confirmed the lock tabs would slide back on the dowel. Am i missing something silly like the clutch needs to be engaged?

    I did take a break from the adjustment process and pulled the pick up tube. there was some debris but the strainer was about 60% clear. The previous owner must have pulled the bolt in the bottom because mine was already missing. I read a few threads that say this is "ok" to keep tube from cracking. I then decided to pull the pump while I was at it. The pump appears to have suction when turning by hand. The drive gears look to be in good shape but there is a little fore/aft movement on the pump driven gear shaft. I plan to pull it apart to look things over.

    One thing I notices was the absence of wear on the clutch oil pump gears. I went back to messing with the clutch adjustment and noticed the oil pump drive gear appeared to slide forward when engaging the clutch? It appears to be enough movement to allow the gears not to mesh with oil pump. I think it is time to pull the whole assembly and go though it unless someone had some ideas on what else to look for. I have the service manual and it appears to be a job best done standing on my head.

  7. #7
    Join Date
    Apr 2007
    Location
    Pioneer Valley, Western MA
    Posts
    304

    Default

    1 thing that should be in the system IS the strainer in the flywheel side. It has a magnet to prevent chips, metal grindings etc. from going to the pump. I just did a late D4 that was locked up in pilot bearing and could not shift any gear. The shavings had seized the pump and twisted off the pump shaft. Also twisted the hubs in the clutch friction disks. it is a pain in the ass to stand on your head to do this job. There is a row of bolts that holds the clutch support use a 9/16 flex socket and 10 in extension. You can get your hand in there. Patience will be your reward.

    Good luck
    Herb
    USA M2 5E3562SP

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