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The Practical Pumping Handbook .......... ::::::: --- ::::: .... :::: ---:::::::: ..... ::::: ...... :: ::::::::::::::

The double row, angular contact
bearing is a common option as a
thrust bearing and is essentially
two rows of beatings in a common
race. It has a substantial thrust
capacity in either direction, and a
higher radial capacity due to the
two rows of balls. Newer designs
and heavier duty pumps tend to
use the duplex arrangement of
single row angular contact
bearings instead of the double row
arrangement.
A single angular contact bearing is Figure 7.7: Double row bearing (Reproduced
designed to support a heavy thrust with permission of SKF USA Inc.)
load in one direction only. It can
also handle a moderate radial load.
The contact angle is achieved by a
high shoulder on the inner ring
and another high shoulder,
diametrally opposite, on the outer
ring. This design is usually used as
matched pairs of single row
bearings, but it must be noted that
these are usually matched in
production so that an even
distribution of the load can be
achieved without the use of shims.
Three alternative arrangements of
the double angular contact bear-
ings arc possible and the load lines Figure 7.8: Single angular contact bearing
must be properly arranged for the (Reproduced with permission of SKF USA
anticipated thrust loads. Inc.)
In the Tandem arrangement, the load lines are parallel and the pair can
accommodate axial loads in one direction only with the loading being
evenly divided between the two bearings. This arrangement is only used
when the design of the pump guarantees the resultant thrust in one
direction only.

In the Face to Face arrangement, the load lines converge as they
approach the bearing centcrline. This arrangement can accommodate
axial loads in both directions, but by only one bearing at a time.

It is interesting to note however that, in this arrangement, it is the
second bearing that transfer the load from the inner race, through the