Excavator slewing bearings are critical components, responsible for supporting the upper structure and transferring operational loads. Due to their constant exposure to heavy loads and harsh working environments, they are prone to failure, with abnormal noise being a frequent symptom. Identifying the root cause of such noise is essential for effective troubleshooting.

While a uniform rolling sound from new bearings is normal, and minor initial noises may disappear after a run-in period, pronounced or unusual sounds require immediate attention. The primary causes and corresponding solutions are outlined below:

1. Improper Installation: Irregular mounting surfaces or loose bolts can induce negative clearance in the raceway, leading to noise and potential gear tooth fracture. Regular inspection and proper bolt tightening to specified torque are necessary.

2. Contamination: The presence of foreign particles like sand or metal chips inside the bearing causes irregular vibration and stiffness. Thorough cleaning of all components during assembly and using clean, high-quality grease are vital preventive measures.

3. Lubrication Issues: Inadequate, uneven, or degraded grease, as well as incorrect lubricant type, are common culprits. The solution lies in using the correct specification of grease and adhering to a strict, timely regreasing and replacement schedule.

4. Seal Damage: Worn or damaged seals fail to retain grease and allow contaminants entry. Inspecting seal integrity and ensuring the material is resistant to aging and lubricants is crucial for prevention.

5. Surface Damage: Cracks, indentations, or corrosion on rolling contact surfaces can create a periodic, knocking noise. Careful handling during installation to avoid impact and using higher viscosity lubricants can mitigate this issue.

6. Severe Wear: Significant wear of the raceway and rolling elements inevitably generates operational noise, often indicating that bearing repair or replacement is required.

Proactive maintenance focused on correct installation, contamination control, and proper lubrication is key to minimizing slewing bearing failures and ensuring excavator reliability.