Angular Contact: Face-to-Face vs. Back-to-Back 2

[RefineryRR]

What is the impact (or consequence) of installing a pair of angular contact bearings (e.g. 7310BG) in a Face-to-Face orientation, vs. a Back-to-Back orientation?
Similarly, what are the benefits & disadvantages of each configuration?

 

[AidanMc]

Bearing companies should have this kind of information in their catalogs, for example NHBB has this information in the catalog for their HiTech division (page 48 of 70 in my copy):

http://nhbb.com/reference/catalogs.aspx

The biggest reason to use a back to back configuration is that it will have better resistance to moments in the shaft. On the other hand, that means that a face to face orientation can tolerate a bit more misalignment.

Aidan McAllister
Metallurgical Engineer

 

[Tmoose]

Is your arrangement spring or rigidly preloaded?

If rigidly preloaded, and If speeds are very high at all or the rotor shaft gets warm ( electric motor ) then DB / back-to-back / "O" arrangement is less susceptible to thermal preload increase.

If uniform temperature is assumed ( highly improbable in reality ) there may be a bearing spacing that introduces no thermal preload increase

 

[chammany]

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 centers makes this arrangement particularly well suited to support moment loads.

Face-to-face arrangement:
In a face-to-face 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 shorter span between effective bearing centers makes face-to-face arrangements less suitable to support moment loads compared to bearings in a back-to-back arrangement.
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.