Download Bearing self study guide

The word “radial” means in the direction of a radius: moving from the
circumference inward, or the center outward. In this case it moves from
the outside in. A radial load pushes down, from the outer race inward to
the balls, cage and inner race at the center of the bearing. The load is at
right angles (90º) to the shaft on which it is being supported. (fig. 4).
Radial load
(fig. 4)
“Thrust” means a pressure or pushing force exerted by one part against a
touching part. Pressure is exerted sideways, pushing the shaft either right
or left. This shaft movement then pushes the inner race of the bearing in
the same sideways direction. The line of pressure, that is, the load, runs
parallel to the shaft (fig. 5).
An “angular” load is actually a combination of radial and thrust loads.
As the load moves at an angle toward the shaft, it pushes against the
corner of the inner race. Pressure is transmitted diagonally, through the
corner of the race, cage and rolling elements, to the opposite corner of the
outer race (fig. 6).
Guide moving parts
Thrust load
(fig. 5)
Angular load
(fig. 6)
The arrows above show how
a load is dispersed through
the balls or rollers of a
bearing.
8
The third function, to guide moving parts, is a result of the other two
functions. By supporting a load while reducing friction, a bearing guides
shaft operation. It assists the movement of crucial shafts, wheels and
pivots. Without a bearing, the rotating part could not continue operating
on a smooth, constant basis.