Angular contact bearings are designed such that there is an angle between the races and the balls when the bearing is in operation. An axial load passes in a straight line through the bearing, whereas a radial load takes an oblique path that tends to want to separate the races axially. So the angle of contact on the inner race is the same as that on the outer race. Angular contact bearings are typically assembled with a thrust load or preload. The preload creates a contact angle between the inner race, the ball and the outer race. The preload can be done while manufacturing the bearing or it can be done when the bearing is inserted into an application.
The contact angle is measured relative to a line running perpendicular to the bearing axis. Angular contact bearings are capable of withstanding heavy thrust loads and moderate radial loads. The larger the contact angle (typically in the range 10 to 45 degrees), the higher the axial load supported, but the lower the radial load. In high speed applications, such as turbines, jet engines, dentistry equipment, the centrifugal forces generated by the balls will change the contact angle at the inner and outer race.