The Challenge: Complex Gearbox Degradation
A critical multi-stage gearbox began exhibiting severe vibration issues, indicative of deteriorating performance. Unusual noise patterns and increasing vibration trends were detected across multiple measurement points, signaling a complex problem affecting several internal components.
Diagnostic Approach: Multi-Technique Vibration Analysis
Our advanced vibration analysis team deployed a comprehensive suite of diagnostic techniques to precisely identify the root causes of the degradation:
- Spectrum Analysis: Identified outer race defects on multiple shafts (bearing 23260, 22248CC).
- PeakVue Analysis: Confirmed bearing defects specifically on output shaft bearings.
- Time Waveform Analysis: Revealed clear impact signatures, directly pointing to gear damage.
- Frequency Domain Analysis: Pinpointed abnormalities in gear meshing frequencies.
Technical Analysis: Pinpointing Core Faults
Our in-depth analysis revealed a combination of critical issues:
Primary Faults Identified:
- Bottom output shaft (C) bearing 23260: Significant outer race defect (0.4G amplitude).
- Intermediate shaft bearing NNU 4164: Clear signs of bearing deterioration.
- Input shaft bearing 22248CC: A minor inner race defect.
- Intermediate shaft pinion: Severe gear tooth damage.
Advanced Diagnostic Indicators:
- Meshing frequency sidebands confirmed severe pinion wear.
- Time waveform impacts correlated with shaft rotational frequency.
- Frequency transmission throughout the entire gearbox structure confirmed widespread issues.
Solution Implementation: Comprehensive Rectification
Based on our precise diagnostics, a comprehensive rectification plan was executed:
- Complete Dismantling: The entire gearbox was fully dismantled for thorough inspection and assessment of all components.
- Component Replacement: All affected bearings on the C and D shafts were completely replaced.
- Gear Train Renewal: The entire intermediate gear shaft (B), including the severely damaged pinion, was replaced.
- Quality Verification: Post-repair vibration analysis was performed to validate the effectiveness of the rectification and ensure optimal performance.
Results Achieved: Significant Performance Improvement
The targeted intervention led to dramatic improvements in gearbox performance and stability:
Output shaft vibration (from 7.1mm/s to 2.4mm/s)
Bottom shaft bearing vibration (from 0.5G to 0.07G)
Gear meshing frequency abnormalities
Normal operational sound levels
Business Value: Extended Life & Prevented Downtime
This comprehensive repair yielded substantial business value:
- Extended Asset Life: Gearbox life extended by an estimated 10-15 years.
- Cost Avoidance: Representing a significant $500,000 in replacement cost avoidance.
- Prevented Catastrophic Failure: The predictive approach prevented a complete breakdown that could have resulted in 2-3 weeks of unplanned downtime, saving significant production losses.