Bearing Selection

The selection of bearings is consists of the following steps which are described in further detail on this page;

1. Select bearing type suitable for load condition

2. Select bearing arrangement suitable for load condition

3. Dimension bearings

4. Select bearing housing design

Selection of bearing type

The table below shows level of suitability of different bearing types for different conditions.

Selection of bearing arrangement

There are three basic bearing arrangements:

1. Face to face

2. Back to back

3. Tandem

These arrangements can also be combined.

Back-to-back arrangement

In a back-to-back arrangement, 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."

Face-to-face arrangement

In a face-to-face arrangement, 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 shorter span between effective bearing centres makes face-to-face arrangements less suitable to support moment loads compared to bearings in a back-to-back arrangement."

Tandem arrangement

The use of a tandem arrangement provides increased axial and radial load carrying capacity compared to a single bearing. In a tandem arrangement, 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."

Examples

Universally matchable single direction bearings can be arranged in various ways depending on the stiffness and load requirements of the application. The possible arrangements are shown in the image, including the applicable designation suffixes for matched sets. If misalignment cannot be avoided between the bearing positions, face-to-face bearing arrangements are recommended. They are less sensitive to misalignment than back-to-back bearing arrangements. Combinations of tandem arrangements with back-to-back or face-to-face arrangements are usually selected to maximize the stiffness or load carrying capacity of a bearing set in a particular direction. This is the case, for example, when extended, preloaded, vertical or overhung screw drives must be supported."