Troubleshooting Common Issues with Slewing Bearings

Lack of Flexibility in Slewing Bearing Rotation

Slewing bearings undergo rigorous inspection and trial operation before leaving the factory, ensuring their qualification as reliable products. If stiffness is observed, the following methods can be employed for troubleshooting:

Newly Purchased Product with Limited Rotational Flexibility:

Check the production date of the slewing bearing. If it has been in storage for an extended period (over six months) in cold climates, the lubricating grease inside the raceway may become viscous, leading to operational stiffness, especially in colder regions during winter.

Resolution: Apply additional force during rotation. If smooth rotation is achieved without abnormalities, normal usage can proceed. If accompanied by abnormal noises, inspect for severe damage during transportation and provide feedback to our company's sales and service department for further handling.

Post-Installation Operational Stiffness:

Re-machine the main machine mounting surface to meet specifications or use the shimming method for adjustment.

Adjust the clearance between the large and small gears according to specifications, paying special attention to minimizing gear backlash.

Verify that there are no foreign objects inside the gear meshing positions.

Poor meshing of large and small gears.

Foreign objects lodged inside the large and small gears.

Poor alignment between the main machine mounting surface and the slewing bearing mounting surface may result in the inability to compensate for axial clearances after installation. This could place the slewing bearing in a negative clearance state, making rotation difficult (sometimes accompanied by abnormal noises).

Potential Causes:

Resolution:

Operational Stiffness During Use:

Refill lubricating grease according to specifications.

Inspect and replace damaged sealing strips.

Verify the meshing conditions of the large and small gears, ensuring there are no foreign objects or broken teeth.

Insufficient lubricating grease; fill as required.

Damaged sealing strip, allowing foreign objects to enter the raceway, especially in harsh operating conditions with dust intrusion.

Check the meshing conditions of the large and small gears for the presence of foreign objects or broken teeth.

Possible Causes:

Resolution:

If the slewing bearing still fails to rotate after taking the above measures, there may be internal faults in the raceway.

Unusual Noises 

Slight Abnormal Noises during Idle Rotation of New Products:

Slight abnormal noises during idle rotation are normal and typically disappear naturally after several dozen rotations. If persistent, it may result from slight deformation during transportation. However, if the rotation is flexible and normal, installation can proceed with confidence. The abnormal noises should naturally diminish after some usage. If the sounds remain prominent or persist after a certain period (usually 2-4 months), prompt contact with our company's after-sales service department is recommended.

Abnormal Noises During Trial Operation after Assembly:

Check whether the mounting surface is flat and meets requirements. Surface roughness not meeting specifications can cause negative clearance in the raceway, resulting in abnormal noises. The resolution is similar to that of "Post-Installation Operational Stiffness."

Poor meshing of large and small gears, with intermittent tightness and looseness causing abnormal noises during maximum gear backlash.

Abnormal Noises During Usage:

Insufficient lubricating grease in the raceway, resulting in collision sounds between rolling elements and separators. This can be resolved by timely oil replenishment.

Presence of foreign objects in the raceway, such as sand particles or iron debris. This condition is often accompanied by difficult rotation, especially in harsh operating environments. Check for damage to the sealing strip.

Loose installation bolts causing elastic deformation in the slewing bearing, leading to negative clearance. Address these issues promptly.

Initially, confirm if the sounds are indeed emanating from the slewing bearing. Some sounds from steel structures or other components might be mistakenly attributed to the slewing bearing. To distinguish the source, stop the rotation of the slewing bearing while allowing other components to operate normally.

Possible Causes:

These measures aim to identify and resolve abnormal noises in slewing bearings, ensuring their optimal performance and longevity.

Swinging

After the slewing bearing is loaded, the clearance is approximately 3-5 times that of the factory inspection (three-point inspection method). Within this range, it can continue to be used.

(1) Loose installation bolts causing swinging during operation. Please immediately check all inner and outer ring installation bolts and tighten them according to specifications.

(2) Insufficient rigidity in the steel structure supporting the slewing bearing, causing elastic deformation during loading and resulting in overall swinging of the slewing bearing. Increase the strength of the steel structure supporting the slewing bearing.

(3) Check for overloading operations and strictly follow the procedures.

(4) Prolonged overloading operations leading to roller path crushing and excessive clearance.

Tooth Breakage

In the event of tooth breakage in the slewing bearing, the site should be secured, and immediate notification to our company's after-sales service department for analysis and resolution is required.

(1) Installation-Related Causes:

Inadequate adjustment of the clearance during the installation of the large and small gears, not meeting requirements, resulting in poor meshing during operation and leading to tooth breakage.

Adjust the clearance strictly according to specifications.

Failure to adjust the meshing clearance between the large and small gears at the maximum tooth jump position as required, causing the small gear to jam and result in tooth breakage during operation.

Perform meshing adjustment at the position marked with green paint on the small gear and conduct a trial run after proper adjustment.

Non-parallel alignment of the axes of the large and small gears, leading to poor meshing after installation and causing tooth breakage.

Ensure parallel alignment of the axes of the two gears.

Loose installation bolts of the slewing bearing causing poor meshing of the large and small gears and resulting in tooth breakage.

Tighten the bolts according to specifications.

(2) Usage-Related Causes:

Violation of operational procedures, overloading, forced rotation, and collision with obstacles by the main engine.

Operate strictly in accordance with the prescribed procedures.

Foreign objects getting stuck in the meshing area between the slewing bearing and the small gear during operation.

Ensure cleanliness of the large and small gears and conduct regular inspections.