Axial clearance and fit are specified to allow NSK wheel bearings to operate within an optimal preload range (life, rigidity, creep, and heat generation).

Fit and preload

The preload must be pre-adjusted based on the fit with other components and nut clamping force, which reduces axial clearance.

For calculating tolerances, NSK has standard preload settings of zero to negative dearances using the 30 method and maximum preload of 9800N using the direct sum method.

Recommended fitting measurements

Note:
1) The dimensional tolerance of the diameter between inner rings and outer rings of NSK hub unit bearings is in compliance with JIS0.
2) Excessive fastening by fitting bearing inner rings may cause defects (high pressure, deformation of pressed surface, plastic deformation, cracking of inner rings). Check to see that the maximum stress on the inner rings does not exceed 147 MPa.

Fitting tests

when mounting NSK wheel bearings on vehicles, use actual components to confirm that the axial clearance is properly set and the preload is within the appropriate range as specified by the users.