In a back-to-back bearing arrangement (fig. 1
), the load lines diverge along the bearing axis. Axial loads acting in both directions can be accommodated, but only by one bearing or bearing set in each direction.
Bearings mounted back-to-back provide a relatively rigid bearing arrangement. The wide span between bearing effective centres makes this arrangement particularly well suited to support moment loads.
In a face-to-face bearing arrangement (fig. 2
), the load lines converge along the bearing axis. Axial loads acting in both directions can be accommodated, but only by one bearing or bearing set in each direction.
The short span between effective bearing centres makes face-to-face arrangements less suitable to support moment loads.
The use of a tandem arrangement provides increased axial and radial load carrying capacity compared to a single bearing. In a tandem arrangement (fig. 3
), the load lines are parallel so that radial and axial loads are shared.
The bearing set can only accommodate axial loads acting in one direction. If axial loads act in both directions, or if combined loads are present, additional bearing(s) adjusted against the tandem arrangement must be added.
Universally matchable bearings and matched bearing sets can be arranged in various ways depending on the stiffness and load requirements of the application. The possible arrangements are shown in fig 4
, including the designation suffixes applicable to matched bearing sets.
To decrease inventories and improve parts availability, SKF recommends using universally matchable bearings whenever possible. With universally matchable bearings, a multitude of different bearing sets can be obtained.