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Contact stiffness (Cɣ) in gear.

  1. Feb 18, 2014 #1

    When I discuss about gears NVH, the term contact stiffness(Cɣ) comes across very often. It is given with a nominal mean value with its upper and lower fluctuation. I can thus understand that the stiffness varies from the start of mesh till end of mesh reaching the mean value at it's pitch point.

    Now my doubt is how do the mean value of stiffness and fluctuation limit influence in gear vibration behavior. Generally what is the range kept for an automobile transmission? If I want to increase / decrease the mean value and fluctuation of stiffness what are the main gear parameters that I should play with?

  2. jcsd
  3. Feb 19, 2014 #2


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    I have no idea about gear vibration dependency on stiffness, or the stiffness range expected...

    To increase gear tooth stiffness I would consider the following;

    1. Increase the contact angle so teeth are more stubby.
    2. Use less but bigger teeth.
    3. Widen the gear.
    4. Adjust base circle to pitch circle ratio.
    5. Use helical gear to average the stiffness over contacts.
    6. Increase contact ratio. Consider an internal gear.
    7. Change material selection. Use steel, cast iron, or carbide.
  4. Feb 19, 2014 #3
    Thanks, Baluncore.
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