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Recent content by rewindr

  1. rewindr

    Motor Winding Predictive Testing

    Surge testing is not a good PM tool since it is potentially destructive and is far from foolproof to understand the results. I have personally failed many machines that I surge tested. It is essentially an AC hipot. I have also personally seen failed windings with large obvious coil failures and...
  2. rewindr

    Spark problem of DC motor

    A few reasons for sparking include; Low spring tension, poor brush seating, wrong brush grade, too lightly or too heavily loaded, shorted interpoles, off neutral brush location, commutator condition including roundness, film, undercutting and edge condition, vibration and poor quality DC power...
  3. rewindr

    measuring motor efficiency

    Binsfeld publishes accuracy but check with them. The device is self balancing as is consists of a battery and sending unit located on opposite sides of shaft. It includes a reciever that can be scaled in a fashion to make the conversion intuitive, such as 100 in-lbs / volt. There is no upper...
  4. rewindr

    measuring motor efficiency

    Binsfeld Engineering makes a shaft mounted battery operated strain gage torque measuring device I have used successfully to measure output torque of a round shaft. The equipment cost 3-4K. A watt meter can be used to measure input although we have used more sophistated instrumentation...
  5. rewindr

    sleeve bearing design

    Yes I am talking about the axial wedge that is usually in the lower half of the bearing. Typically I have seen it 1" wide on a 4" journal or so and is not quite as long as the bearing. Several times I have cured hot (160F) running bearings by making this groove a little deeper and a...
  6. rewindr

    sleeve bearing design

    I am interested in finding information on bearing designs. In particular I have found several cases where the oil wedge or side pocket in a sleeve bearing was inadequate and allowed the bearing to run hotter than normal. Making the wedge larger and deeper solved the problem. Are there any rules...
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