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Gear box drifting


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  • Gear box drifting


    I have a gearbox that is drifting very badly. They are the old slow style, I think National. This thing is on a sweep and man is it loose. I know there have been some threads about this before but I forgot what alll I can do.

    Thanks in advance for any help

  • #2
    Re: Gear box drifting



    • #3
      Re: Gear box drifting

      I believe Chad was referring to the carbon brushes #785-502 020. If the brake disc #785-502-003 is pitted or scored new brushes will only slightly improve braking. It is best to have the disc turned at a machine shop for $5-$10. The disc’s used to cost ~$50 but don’t show up in AMF’s or Vantage’s 2004 price book. Stahls shows them in their book, but don’t know if still available.

      If problem persists with reconditioned disc and new brushes, most likely gearbox needs re-shimmed or you have something electrical (chassis contacts, capacitors, centrifugal mechanism…ect.) can cause coasting.



      • #4
        Re: Gear box drifting

        Oops, right you are. Two off.


        • #5
          Re: Gear box drifting

          Severe or "uncorrectable" drift is caused by a worn gearbox... if you can't shim the motor or put enough tension on the carbon brushes to stop the drift, it's time for a gearbox rebuild.
          Overshimming or putting extra tension on the motor isn't recommended... it'll cause a lot of unnecessary heat and wear on the motor, and will eventually burn it out.

          You can cheat with gearboxes... when they get too 'loose' to hold the table from drifting, they can be moved to a sweep position, where they will usually run several more years just fine. When the sweep starts drifting, the gearbox has to be worked over. Always PERMANENTLY mark (no masking tape... paint marker or attached tag) a gearbox that was moved from table to sweep due to drifting... it'll eliminate a lot of confusion down the road when the drift starts on the sweep and everyone is scrambling to figure out why.
          <span style="font-style: italic">Educatio est omnium efficacissima forma rebellionis</span>


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