The main characteristic of a spherical bearing is its capability to align itself with the shaft, since it can act as a swivel. A spherical bearing is assembled by pressing the equatorial diameter against the housing with a spring or a serclip. The assembly pressure must allow the bearing to swivel, but must also support the bearing when it is not working. This double characteristic is represented as the swiveling moment tolerance. The ideal situation is shown in the next figure: the optimal swiveling moment is located between the two limit lines, and it changes depending on the product between the bearing inner diameter and the bearing length.

Swiveling moment of spherical bearings