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Estimating the frictional moment

Under certain conditions, the frictional moment can be estimated with sufficient accuracy using a constant coefficient of friction μ. The conditions are:
  • bearing load P ≈ 0,1 C
  • good lubrication
  • normal operating conditions
The frictional moment under these conditions can be estimated using
M = 0,5 μ P d

For radial needle roller bearings, use F or Fw instead of d.

=frictional moment [Nmm]
=constant coefficient of friction for the bearing (table 1)
=equivalent dynamic bearing load [N]
=bearing bore diameter [mm]
=inner ring raceway diameter [mm]
Fw =diameter under the rollers [mm]
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