I. Functions

1. Supporting the Journal

   • Ensures smooth rotation of the shaft in its designated position, critical for high-speed equipment like engines and motors.

   • Provides precise axial positioning, preventing misalignment and mechanical failure.

2. Load-Bearing Capacity

   • Withstands both radial loads (perpendicular to the shaft) and axial loads (along the shaft), making it ideal for heavy-duty applications such as mining and metallurgical machinery.

   • Distributes loads to the machine’s foundation, enhancing stability and reliability.

3. Reducing Friction and Wear

   • A lubricating film (e.g., oil film) separates the journal from the bearing surface, minimizing direct contact and extending component lifespan.

   • Commonly used in industrial equipment requiring long-term operation.

4. Damping and Vibration Absorption

   • Absorbs shock energy and reduces vibration transmission. For example, plain bearings in automotive engines decrease cabin vibrations, improving ride comfort.

II. Advantages

1. Simple and Compact Design

   • No rolling elements or cages, reducing manufacturing costs and fitting space-constrained applications (e.g., small motors, precision instruments).

2. High Load Capacity

   • Continuous surface contact (vs. point/line contact in rolling bearings) makes it suitable for heavy-load scenarios like ship propulsion and industrial machinery.

3. Smooth and Quiet Operation

   • Sliding friction generates less noise than rolling-element bearings, ideal for medical equipment and precision devices requiring silent operation.

4. Excellent Vibration Damping

   • The elastic properties of the lubricating film dissipate vibration energy, enhancing reliability and machining accuracy (e.g., machine tool spindles).

5. Adaptability to Harsh Environments

   • Custom materials (e.g., ceramics, self-lubricating composites) and lubrication methods (e.g., solid lubrication, oil mist) enable performance in extreme conditions (e.g., high temperature, corrosion, humidity), such as in chemical pumps and turbines.

Application Examples

Conclusion

Plain bearings, with their simplified design, superior load-bearing and vibration-damping capabilities, play a vital role in industries such as manufacturing, transportation, and precision engineering. Their flexibility and adaptability make them indispensable in high-load, low-noise, and harsh-environment applications.