This radial play is necessary for proper operation, however, in most applications, it is also necessary to help reduce or eliminate the internal clearance to maintain correct functionality.
To remove this internal clearance, an axial load can be placed on a bearing race independently of the external load placed on it. This is called preloading, and it ensures constant contact – reducing or eliminating any play that may occur between components. This becomes a critical factor in most high-precision and high-speed applications.
There are two types of bearing preload: fixed and spring. In fixed bearing preload, the position of the inner and outer races of each bearing is mechanically fixed using either a dead weight (adhesive based) or through building in an axial adjustment that puts pressure on the bearings. Spring loading provides a constant load that can accommodate slight misalignments and is less expensive than fixed preloading.
Read the full article in the May issue of DPA