Back-to-back arrangement
In back to back arrangement a gap is provided between inner
races and when installed, this gap is closed and producing a preload on the
bearings. 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. Back to Back bearing
arrangement is a type of duplex bearing arrangement where the two half are
placed so that contact angle lines of the bearing diverge inwardly.
DB (Back-to-Back) arrangement has higher moment stiffness
than the DF (Face-to -Face) arrangement. Under the same preload, DB and DF have
identical radial and axial stiffness. 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
Face to face bearing arrangement (DF arrangement) is a type
of duplex bearing arrangement where the two half are placed so that contact
angle lines of the bearing converge inwardly. 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.
In face to face arrangement a gap is provided between outer
races and when installed, this gap is closed and producing a preload on the
bearings. DF (Face to face bearing) arrangement has lower moment stiffness, so they must be spaced
sufficiently to provide resistance to moment load.
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. This arrangement makes a very heavy duty thrust bearing arrangement,
but it will not carry any radial load and accepts thrust loading in only one
direction.
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.