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Bearing modulus

From Wikipedia, the free encyclopedia

Bearing modulus is a modulus used in journal bearing design. It is a dimensionless number.[1]

Formula

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Bearing Modulus (C) is C = (Zn/p) where

  • Z = oil viscosity
  • n = speed of rotation (rpm)
  • p = bearing pressure(N/MM2)

For any given bearing, there is a value for indicated by C, for which the coefficient of friction is at a minimum. The bearing should not be operated at this value of bearing modulus, since a slight decrease in speed or a slight increase in pressure will make the part of a shaft or axle that rests on bearings operate in partial lubrication state resulting in high friction, heating and wear.

To prevent this, the average value of Bearing modulus should be

  • Zn/p >= 3C

or for large fluctuations and heavy impact loads

  • Zn/p = 15C (approx)

References

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  1. ^ Karwa, Rajendra (2002). A Text Book of Machine Design. Firewall Media. ISBN 978-81-7008-833-2. Retrieved 2 January 2012.