Bearing Mounting and Fitting: Shoulder Design || Dynaroll Bearing Design Factors Part 2

When a bearing is located against a shoulder in a mating part, care must be taken that the rim of the shoulder clears the opposing ring. This is achieved when the diameter of the shoulder has clearance over the opposing race land diameter.

Maximum shaft shoulder diameter = Outer ring land diameter – Clearance*
Minimum housing diameter = Inner ring land diameter + Clearance*
*Clearance should be > 0.010 inch (0.25 mm) to allow for normal tolerances.

The corner radius of the shoulder (ra) should be less than the fillet radius (r) of the mating bearing to allow the bearing to fully seat against the shoulder. Bearing land diameters and the maximum shoulder corner fillet radii for bearings are given in bearing specifications in most bearing catalogs.

Preload Assembly Methods

Preload is the force applied between the races of a pair of bearings to remove the axial play and to further compress the bearings to provide both axial and radial stiffness. It is an important design parameter, affecting rotational performance and lifetime of a bearing assembly. After preload, the resulting ball contact angle a must be considered (see Part I – Bearing Geometry).

Standard preload - Inner rings pressed together	Outer rings pressed together (maximum stiffness)

Bearing Mounting and Fitting, Page 6: Bearing Preload in a Ball Bearing Pair