Different types of bearings possess distinct characteristics due to their unique designs. Given the diversity and complexity of their specific installation positions and application scenarios, there is no fixed pattern for selecting bearing types. To ensure a bearing is suitable for the specific installation position and operating conditions of a host machine, it is recommended to comprehensively consider the following key factors:

I. Installation Space

In mechanical design, the dimensions of the shaft are usually determined first, and then bearings are selected based on the shaft dimensions. Generally speaking:

- Ball bearings are preferred for small shafts;

- For large shafts, cylindrical roller bearings, spherical roller bearings, and tapered roller bearings can be selected (ball bearings may also be used in some cases).

If the radial space at the bearing installation position is limited, bearings with a small radial cross-sectional height should be chosen, such as needle roller bearings, certain series of deep groove ball bearings, angular contact ball bearings, cylindrical roller bearings, spherical roller bearings, and thin-walled bearings; if the axial space is limited, bearings with a small width should be selected.

II. Load Conditions

The magnitude of the load is usually the key factor determining the bearing size:

- Under the same external dimensions, roller bearings have better load-carrying capacity than ball bearings;

- Ball bearings are suitable for light or medium-load conditions, while roller bearings are more suitable for withstanding heavy loads.

From the perspective of load types:

- For pure radial loads: Deep groove ball bearings or cylindrical roller bearings can be selected;

- For pure axial loads: Thrust ball bearings or thrust cylindrical roller bearings can be selected;

- For combined radial and axial loads: Angular contact ball bearings or tapered roller bearings are generally selected;

- If the radial load is large and the axial load is small: Deep groove ball bearings, or cylindrical roller bearings with flanges on the inner and outer rings, can be selected;

- If there is significant deformation of the shaft or housing, or poor installation alignment: Self-aligning ball bearings or spherical roller bearings can be selected;

- If the axial load is large and the radial load is small: Thrust angular contact ball bearings or four-point contact ball bearings can be selected; if self-aligning performance is also required, thrust spherical roller bearings should be chosen.

III. Operating Speed

The operating speed of rolling bearings mainly depends on their allowable operating temperature. Bearings with low friction resistance and minimal internal heat generation are more suitable for high-speed operation:

- When only subjected to radial loads: Deep groove ball bearings and cylindrical roller bearings can achieve relatively high speeds;

- When subjected to combined loads: Angular contact ball bearings should be selected; high-precision angular contact ball bearings with special designs can achieve extremely high speeds;

- The speed of all types of thrust bearings is lower than that of radial bearings.

IV. Rotational Accuracy

For most mechanical equipment, bearings with Class 0 tolerance can already meet the requirements of the host machine; however, when strict requirements are imposed on the rotational accuracy of the shaft (such as machine tool spindles, precision mechanical equipment, and instruments), bearings with higher tolerance classes should be selected, such as deep groove ball bearings, angular contact ball bearings, tapered roller bearings, cylindrical roller bearings, and thrust angular contact ball bearings.

V. Stiffness Requirements

The stiffness of rolling bearings is determined by their elastic deformation under load, which is usually small and negligible. However, in some equipment (such as machine tool spindle systems), the static stiffness and dynamic stiffness of bearings have a significant impact on system characteristics:

- Generally speaking, the stiffness of roller bearings is higher than that of ball bearings;

- The stiffness of various types of bearings can be improved to varying degrees through reasonable "preloading".

VI. Vibration and Noise

The inherent noise and vibration of bearings are usually low, but for small and medium-sized motors, office machinery, household appliances, and instruments with special requirements for noise and operational stability, low-noise bearings should be selected.

VII. Axial Displacement Compensation

The most common configuration of bearings is to install a set of axially positioned "fixed bearings" at one end of the shaft and a set of axially movable "floating bearings" at the other end to prevent the shaft from seizing due to thermal expansion and contraction.

Commonly used "floating bearings" are cylindrical roller bearings without flanges on the inner or outer ring; in this case, an interference fit can be adopted for the fit between the inner ring and the shaft, or between the outer ring and the housing bore;

Sometimes, non-separable deep groove ball bearings or spherical roller bearings can also be used as floating bearings, but during installation, a clearance fit should be adopted between the inner ring and the shaft, or between the outer ring and the housing bore to ensure sufficient axial movement freedom of the inner ring or outer ring.

VIII. Friction Torque

- The friction resistance of ball bearings is smaller than that of roller bearings;

- Under pure radial loads: Radial contact bearings have small friction resistance; under pure axial loads: Axial contact bearings have small friction resistance; under combined loads: Angular contact bearings whose contact angle is close to the load angle have the minimum friction resistance;

- Instruments and mechanical equipment with low requirements for friction torque are more suitable for selecting ball bearings or cylindrical roller bearings;

- In addition, low-friction torque bearings should avoid the use of contact seals, and it is recommended to adopt oil drop lubrication, oil-air lubrication, or other lubrication methods that help reduce wear.

IX. Installation and Disassembly

For mechanical equipment that requires frequent installation and disassembly, bearings with a cylindrical inner bore should be selected, with priority given to separable angular contact ball bearings, tapered roller bearings, separable cylindrical roller bearings, needle roller bearings, and thrust bearings;

Bearings with a tapered inner bore can be directly installed on a tapered journal, or installed on a cylindrical journal with the help of a locking sleeve or withdrawal sleeve, making installation and disassembly more convenient.