Double row slewing bearing noise fault how to troubleshoot

Double-row slewing bearings are crucial components in many heavy-duty machines, and noise can be a significant indicator of an underlying problem. Troubleshooting the noise involves a systematic approach to identify the cause and implement the correct solution.

Double row slewing bearing noise troubleshooting

1. Identify the Type of Noise and When it Occurs:

Normal Sounds: A new slewing bearing might produce a soft, uniform rolling sound of steel balls. This is usually normal and may fade after some rotation.

Abnormal Loud Noise: This indicates a problem and requires attention.

Grinding, Popping, Clicking, or Cracking: These are strong indicators of issues.

When does it occur?

New Bearing (before/after installation): Could be slight deformation from transport or improper installation.

Bearing in Service (after some use): Likely wear, lubrication issues, contamination, or loose components.

Under Load vs. No Load: Helps differentiate between issues related to stress and more general problems.

2. Initial Checks (General Troubleshooting):

Confirm the Source: Is the noise definitely coming from the slewing bearing? Sometimes, noises from other steel structures or components can be mistaken for bearing noise. Try stopping the slewing ring's rotation while other components continue to work to isolate the sound.

Lubrication: This is often the first and easiest thing to check.

Lack of Grease: Insufficient or aged grease can cause rolling elements and separators to rub, creating noise. Timely greasing (every 100-250 hours of operation, or more frequently in harsh conditions) can often eliminate this.

Inspect Purged Grease: When you pump new grease into the bearing, observe the old grease that is purged out. If you see grit, metal particles, or flakes, it indicates wear or contamination.

Incorrect Lubricant: Using the wrong type of grease or one with unsuitable viscosity can also lead to poor lubrication and noise.

Oil Leakage: Check for signs of oil leakage, which can indicate damage to seals or improper lubrication practices.

3. Installation-Related Issues:

Mounting Surface Flatness: An uneven mounting surface can cause negative clearance in the raceway, leading to noise.

Solution: Re-machine the mounting surface to meet specifications or use shims/washers to achieve standard flatness.

Loose Mounting Bolts: Loose bolts can cause elastic deformation of the slewing bearing and create negative clearance in the deformed areas, resulting in noise.

Solution: Immediately check and tighten all mounting bolts to the specified torque.

Gear Meshing (if applicable):

Poor Meshing or Foreign Objects: Check the meshing of the slewing ring gear with the pinion. Poor alignment, excessive backlash, or foreign objects (like broken teeth) can cause noise.

Solution: Adjust gear backlash, remove foreign objects, and ensure proper alignment.

4. Internal Bearing Issues / Wear:

Contaminants in Raceway: Sand, dirt, burrs, or other foreign objects inside the raceway can cause grinding noises and difficult rotation. This is often accompanied by damaged seals.

Solution: Clean the bearing thoroughly. If seals are damaged, replace them to prevent further contamination.

Raceway/Rolling Element Damage:

Cracks, Indentations, Rust: These can cause periodic vibrations and clicking/popping noises. The noise might vary with installation and lubrication conditions.

Severe Wear: Worn raceways and rolling elements (balls or rollers) can lead to increased clearance, wobbling/rocking motion, and loud popping/cracking sounds, especially under load.

Uneven Wear: Can cause increased torque or binding, indicating uneven load distribution.

Solution: If significant damage or wear is confirmed (e.g., through lubricant analysis showing metal particles, or visual inspection if possible), the bearing may need to be repaired (remanufactured) or replaced.

Excessive Clearance (Play): A new bearing has a specific clearance, but excessive wear can increase it dramatically. This can manifest as a lack of "stiffness" in an extended boom, causing it to rock.

Measurement: Use a dial indicator to measure the amount of tilt when the boom is loaded.

Solution: If clearance is too high due to wear, the bearing likely needs repair or replacement.

5. Other Potential Causes:

Design/Selection Issues: In some rare cases, the initial bearing design or selection might be inadequate for the actual load, leading to premature wear and noise.

Host Machine Issues: Sometimes, the noise isn't from the bearing itself but from other components of the host machine (e.g., motor vibration, frame resonance). Isolate the bearing to rule this out.

Spacer Block Issues: Deformed, crushed, or improperly assembled spacer blocks can cause rolling elements to become blocked or produce abnormal sounds.

Troubleshooting Steps Summary:

Listen and Observe: Characterize the noise (type, intensity, periodicity) and when it occurs (idle, loaded, specific rotation angles).

Check Lubrication: Grease the bearing thoroughly, inspect purged grease for contaminants.

Inspect Mounting: Verify flatness of mounting surfaces and tightness of all bolts.

Check Seals: Look for damage that could allow contaminants in or grease out.

Examine Gear Meshing: If applicable, check for proper alignment, backlash, and foreign objects.

Assess Clearance: If possible, measure bearing play/clearance.

Consider Internal Damage: If external checks yield no results, internal wear or damage to raceways/rolling elements is likely. This often requires professional inspection or disassembly.

Consult Supplier/Manufacturer: If the problem persists after basic troubleshooting, contact the bearing supplier or manufacturer for expert advice, potential repair, or replacement.

Important Considerations:

Safety First: Always follow safety procedures when inspecting or working on heavy machinery.

Documentation: Keep records of maintenance, lubrication, and any observed issues. This helps in tracking trends and diagnosing problems.

Preventive Maintenance: Regular greasing and visual inspections are key to preventing many slewing bearing problems and extending their lifespan. Avoid consistently lifting heavy loads in the same position to distribute wear.