The first chapter of Rolling Bearing Analysis by Tedric Harris is entitled Rolling Bearing Types. It describes different types of rolling element bearings and their strengths and weaknesses. The bearings fit into three different categories: ball bearings, roller bearings and linear motion bearings.
Ball Bearings
- Radial Ball Bearings
The single-row deep-groove conrad assembly bearing is the most popular type of roller bearing. It is best for carrying radial loads; however, it can withstand combined radial and axial loading. It readily accepts shields or seals.
There are several modified versions of this basic design. One is using a filling-slot assembly which allows more balls to be added increasing the load carrying capacity. Another is using a double row of balls which looks similar to two bearings mounted side by side.
Instrument ball bearings are a special version of this type which are smaller and thinner. These are manufactured to more stringent standards and assembled in clean rooms because their small size means even small particles or dimensional deviations will cause serious problems. - Angular Contact Ball Bearings
This type of bearing can support combined radial and thrust loading or high levels of thrust load because of their large contact angles. Typically these bearings are mounted in pairs or a double row bearing is used. Double bearings can be mounted face-to-face or back-to-back so that an axial load from either side can be supported. Alternatively they can be tandem mounted in which case both bearings support a load from the same direction. - Thrust Ball Bearings
Thrust bearings support thrust loads and typically have a contact angle of 90 degrees although any contact angle over 45 degrees is classified as a thrust bearing. These bearings can achieve high speeds and are often mounted on spherical seats to be externally aligning.
Roller Bearings
In comparison to ball bearings roller bearings have a large load carrying capacity, have longer fatigue lives, are harder to align, are more difficult to install, and cost more.
- Radial Roller Bearings
These bearings are capable of high speeds and have low torque friction, but they are not suitable for axial loads. Frequently a double row of bearings is used to increase the load capacity.
One subset of this category is needle roller bearings. These have very small diameter rollers in relation to their length. This gives them greater friction and makes it harder for them to be manufactured to tight tolerances. Sometimes these bearings do not have a cage. - Tapered Roller Bearings
This type of bearing can carry combined radial and thrust loading. Loading forces the rollers against the flange guide increasing friction, so these bearings are not suitable for high speed applications. Tapered roller bearings can also be made in two and four row varieties. - Spherical Roller Bearings
Spherical roller bearings have a raceway which is a portion of a sphere. The crown radii on the rollers are consequently very large as well. Because of the close osculation of the roller and raceway, these bearings have a large amount of friction but also a high load capacity. - Thrust Roller Bearings
Thrust roller bearings can be made using cylindrical, spherical, tapered, or needle rollers. All of these roller types will have limited speeds. The spherical rollers have high load capacity, can support radial and thrust bearings and are self aligning. Using cylindrical rollers will result in a large amount of sliding. The loads on needle rollers need to be kept small.
Linear Motion Bearings
- Ball bushings can be used to allow linear motion instead of sliding lubricated motion. These bearings reduce friction and dimensional changes due to wear of the sliding components.
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