Ball Bearings are probably the most common type of bearing. In a ball bearing, the load is transmitted from the outer race to the ball, and from the ball to the inner race. Since the ball is a sphere, it only contacts the inner and outer race at a very small point, which helps it spin very smoothly. But it also means that there is not very much contact area holding that load, so if the bearing is overloaded, the balls can deform or squish, ruining the bearing.
In these bearings, the roller is a cylinder, so the contact between the inner and outer race is not a point but a line. This spreads the load out over a larger area, allowing the bearing to handle much greater loads than a ball bearing. However, this type of bearing is not designed to handle much thrust loading.
A variation of this type of bearing, called a needle bearing, uses cylinders with a very small diameter. This allows the bearing to fit into tight places.
Ball Thrust Bearings
Ball thrust bearings are mostly used for low-speed applications and cannot handle much radial load. Barstools and Lazy Susan turntables use this type of bearing.
Roller Thrust Bearings
Roller thrust bearings can support large thrust loads. They are often found in gearsets like car transmissions between gears, and between the housing and the rotating shafts. The helical gears used in most transmissions have angled teeth -- this causes a thrust load that must be supported by a bearing.
Tapered Roller Bearings
Tapered roller bearings can support large radial and large thrust loads. They are usually mounted in pairs facing opposite directions so that they can handle thrust in both directions.
Mounted (Pillow Block-Flanged) Bearings
Pillow blocks, the most commonly used type of mounted units, are designed to provide shaft support where the mounting surface is parallel to the shaft axis. The bolt holes are usually slotted for adjustment during mounting. Pillow blocks are supplied in a variety of configurations. Pressed steel pillow block bearings are also available for light-duty applications.
Linear Bearings and Shafts
A linear-motion bearing or linear slide is a bearing designed to provide free motion in one dimension. All linear slides provide linear motion based on bearings, whether they are ball bearings, dovetail bearings or linear roller bearings. XY Tables, linear stages, machine slides and other advanced slides use linear motion bearings to provide movement along both X and Y multiple axis.
Cutaway view of (left) a spherical roller thrust bearing and (right) a radial tapered roller bearing.