Abnormal noise from generator set bearings is a common mechanical failure, which may be caused by poor lubrication, wear, improper installation, or foreign object intrusion. The following are the maintenance steps and precautions for bearing abnormal noise:

 Fault diagnosis and inspection

Identification of abnormal noise characteristics

Metal friction sound: Dry friction may be caused by insufficient lubrication or deterioration of oil quality.

Regular knocking sound: wear and peeling of bearing raceway or rolling elements.

Sharp whistling: Insufficient clearance or improper installation of bearings (such as too tight).

Intermittent abnormal noise: may contain foreign objects (such as sand particles, metal shavings, etc.).

Shutdown inspection

Manual turning: Check whether the bearing rotates smoothly, whether there is any jamming or resistance.

Temperature detection: Use an infrared thermometer to check the bearing temperature. Abnormal high temperatures (over 80 ℃) may indicate lubrication or wear issues.

Visual inspection: After disassembly, observe whether the inner and outer rings, rolling elements, and cage of the bearing are damaged, corroded, or deformed.

Clearance measurement: Use a feeler gauge or micrometer to check the radial/axial clearance of the bearing, and compare it with the standard value to determine if it exceeds the limit.

Common causes and solutions

1. Poor lubrication

Symptoms: High bearing temperature, abnormal noise accompanied by burnt smell.

Handle:

Clean old grease and thoroughly clean bearings and oil passages with kerosene or specialized cleaning agents.

Replace the lubricating grease that meets the specifications (such as lithium based grease, high-temperature lubricating grease), with a grease injection amount of 1/3 to 1/2 of the bearing chamber.

Check if the lubrication system (such as the automatic oiler) is blocked or malfunctioning.

2. Bearing wear or damage

Symptoms: Peeling and pitting of rolling elements or raceway surfaces, and fracture of retaining frames.

Handle:

Replace with a new bearing of the same model (pay attention to the brand accuracy level, such as SKF, NSK).

Check the dimensional tolerances of the journal and bearing seat to avoid secondary damage caused by improper fit.

When using the hot installation method, the heating temperature should not exceed 120 ℃ (to avoid bearing annealing).

3. Installation issues

Symptoms: Abnormal bearing clearance (too tight or too loose), excessive axial/radial runout.

Handle:

Reinstall, ensure that the shaft is concentric with the bearing seat, and use hydraulic tools or copper rods to strike evenly.

Check if the shoulder and locking nut are in place to prevent axial movement.

Leave appropriate thermal expansion clearance for non positioning end bearings.

4. Foreign object intrusion

Symptoms: Particles can be seen inside the bearing, and there are obvious scratches on the raceway.

Handle:

Clean the sealing structure of the bearing seat and replace any failed oil seals or labyrinth seals.

Check the intake filtration system of the unit to prevent dust from entering (especially suitable for outdoor or dusty environments).

5. Abnormal load

Symptom: Abnormal bearing wear is concentrated locally, accompanied by excessive vibration of the unit.

Handle:

Check the alignment error of the coupling (laser alignment instrument calibration, deviation ≤ 0.05mm).

Check whether the generator load exceeds the limit or there is unbalanced current.

Check if the foundation bolts are loose and if the equipment base is level.

Post repair testing

No load test run: Monitor whether the abnormal noise disappears after starting, and monitor the bearing temperature (≤ 70 ℃ is normal).

Vibration detection: Use a vibration analyzer to detect the vibration value of the bearing part (ISO 10816 standard).

Load test: Gradually increase the load to the rated value and observe the stability of operation.

Preventive measures

Regular maintenance: Replace lubricating grease according to the manual cycle (usually every 2000-5000 hours of operation).

Condition monitoring: Use online vibration monitoring system or regularly collect oil samples for iron spectrum analysis.

Environmental control: Keep the computer room clean and dry, avoid moisture or corrosive gases.

Spare parts management: Use original or high-precision replacement bearings to avoid inferior parts.

precautions

When disassembling bearings, direct hammering is prohibited and a specialized puller must be used.

If the bearing is adhered to the journal, heating method (induction heater) can be used to assist in disassembly.

For large generator sets (such as marine or power plant units), it is recommended to contact a professional maintenance team for handling.

Through system troubleshooting and standardized maintenance, the problem of bearing abnormal noise can be effectively solved, and the service life of the unit can be extended. If abnormal noise occurs repeatedly, further check the dynamic balance of the generator rotor or the matching of the transmission system.

Source: Shenzhen Huanyutong Motor Maintenance

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