The outstanding advantage of a ball bearing over a sliding bearing is its low starting friction. If a bearing is rotating, but experiences heavy load that lasts shorter than one revolution, static max load must be used in computations, since the bearing does not rotate during the maximum load.
If the outer ring is not strong enough, or if it is not sufficiently braced by the supporting structure, the outer ring will deform into an oval shape from the sideways torque stress, until the gap is large enough for the rolling elements to escape. The balls are loosely restrained and separated by means of a retainer or cage.
A sideways torque on a radial bearing also applies pressure to the cage that holds the rolling elements at equal distances, due to the rolling elements trying to all slide together at the location of highest sideways torque.
That means that either the ID of the outer ring is large enough, or the OD of the inner ring is small enough, so as to reduce the area of contact between the balls and raceway.
For small bearings this is best done with a press because tapping with a hammer damages both bearing and shaft, while for large bearings the necessary forces are so great that there is no alternative to heating one part before fitting, so that thermal expansion allows a temporary sliding fit.
Use suitable assembly tools to ensure that no assembly forces can be transferred through the balls. One type of self-aligning bearing has two rows of balls and a spherical inner surface on the outer race.
There are three main parts in a ball bearing: two grooved, ringlike races, or tracks, and a number of hardened steel balls.