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Moving Eccentric Adjustment


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  • Moving Eccentric Adjustment

    I have a machine... factory (Jap) A-2 on which I can't seem to nail the eccentric adjustment. I have set according "to the book" and things work fine for a few days and then the son of gun goes down on a spare with the deck lowering hook disengaged... thump! and resets the spare with a loud thunk! It also drops to new pins level when detecting a strike!
    I know to adjust the eccentric (1/32" clearance) but for some reason this adjustment won't stay put on this machine! I would liek your thoughts on why the eccentric ring adjustment won't lock in on this machine? Overtightening the bolts perhaps? Is this a sign that I need to replace the eccentric ring?
    Several months ago on this machine the eccentric cam bolts backed out causing a real mess and we had to replace the 1-1 gear (took the assembly to a machine shop that had a press capable of removing the gear and installing the replacement).
    The adjustment is easy enough but I would like to know why is isn't staying put!

  • #2
    Re: Moving Eccentric Adjustment

    Hop to deck lift shaft adj, first. Make certain machine is over playing surface as it should be. As its a japper, it should be a scotch yoke lowering link, set the deck pinsetting height, then set deck lowering hook to eight and one half inches, deck hieght at strike, 90 degrees.
    Ensure eccentric ring is well lubricated, (most important) and tighten U bolt nuts securely, then when going down to set a new rack, watch eccecntric to make sure it rides two to one and does not try to flip up as two to one rotates, otherwise you will break end of hook off as it tries to clear frame pipe, if it rotates, you have U bolt too tight, keep the U bolt as tight as you can without encuring this problem , again lubrication on the brass ring is critical.
    Hope of some help


    • #3
      Re: Moving Eccentric Adjustment

      As an aside, scotch yokers also have a tendency to break welds at the adj. point on the end of the yoke, and also at the weldment where the c meets the deck lift shaft.
      This usually first manifests itself in a failure to go to first ball, owing to the fact mch. cannot get a strike signal on the deck holding hook, second ball, 90 degrees.
      Don't think thats your problem, but in these situations, one is best advised to check everything related to deck lift shaft, including main and secondary deck lift shaft bearings


      • #4
        Re: Moving Eccentric Adjustment

        Roger...had this problem on a few machines. Found the surface of the 2:1 that the eccentric ring rides on was chewed up causing friction when the machine first starts to cycle. Was probably caused from lack of lubrication over the years. Take the ring off and look at the 2:1. Takes 5 minues to take it off...not so quick to fix though if thats the problem.

        Good luck with this one.

        TSM & TSM Training Development
        Main Event Entertainment
        480-620-6758 for help or information


        • #5
          Re: Moving Eccentric Adjustment

          I agree that lubrication on the eccentric ring could be the culprit.
          The ones I saw mushroomed the eccentric ring causing it to bind up.
          I was able to take the ring off and file down the mushrooming.


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