1. Description of the problem and scope of application
Increased noise and abnormal vibration are critical indicators of degradation of the internal components of the gearbox (gears, bearings, shafts). This manual is intended for the diagnosis of cylindrical, bevel and planetary industrial gearboxes. Timely detection of the causes allows to avoid the catastrophic destruction of the node and downtime of production lines.
Severity classification: Critical (if accompanied by a sudden increase in temperature or metallic knocking), Major (stable, but higher than normal level of vibration).
2. Safety measures
WARNING: Follow all procedures according to LOTO (Lockout/Tagout) protocol. De-energize the drive and block the mechanical energy. Before opening the case or taking oil samples, make sure the gearbox has cooled down (surface temperature below 40°C) to avoid burns. Always use PPE: safety glasses, oil-resistant gloves, special shoes.
3. Necessary tools
| Tool | Specification | Purpose |
|---|---|---|
| Vibroanalyzer | FFT analyzer, 0-10 kHz | Detection of spectral frequencies of vibration |
| Mechanical stethoscope | Industrial type | Localization of the noise source |
| Infrared camera | Resolution ≥160x120 | Monitoring of temperature gradients |
| Clock type indicator | Accuracy 0.01 mm | Measurement of axial and radial backlash |
| Oil analysis kit | Field test | Assessment of contamination and wear of metals |
4. Initial assessment checklist
| Parameter | What to check |
|---|---|
| The load | Does the noise change depending on the load? |
| Frequency | Is the noise constant or cyclical? |
| Last service | Has work been carried out in the last 1000 hours? |
| History of accidents | Were there any sudden stops or overloads? |
| Oil condition | Are there visual signs of chipping or clouding? |
5. Systematic diagnostic algorithm
- Localization of the noise:
- IF noise in the bearing unit → CHECK radial backlash → IF backlash > limit → PROBABLE CAUSE: bearing wear.
- IF noise in the area of engagement of the teeth → CHECK the contact spot → IF spots are uneven → PROBABLE CAUSE: inconsistency of the interaxial distance or misalignment.
- Vibration frequency analysis:
- IF frequency corresponds to shaft revolutions → CHECK coupling alignment.
- IF frequency corresponds to tooth rolling frequency (GMF) → CHECK tooth wear or breakage.
6. Malfunction matrix
| Symptom | Probable reasons | Diagnostic test | Expected result |
|---|---|---|---|
| High frequency squeal | Oil starvation/teeth wear | Checking oil level/pressure | Low level |
| Dull knock (low frequency) | Tooth breakage/bearing wear | Vibration Analysis (FFT) | Peak on harmonics |
| Hum (constant) | Misalignment of the shafts | Laser centering | Deviation > 0.05 mm |
7. Deep analysis of the reasons
7.1. Gear wear
Occurs due to fatigue destruction of the surface (pitting) or abrasive wear due to oil contamination. If not eliminated, it leads to a change in the profile of the tooth, an increase in dynamic loads and a chain destruction of other teeth.
7.2. Degradation of bearings
Most often, it is caused by incorrect installation or a violation of lubrication. Wear of raceways or rolling elements leads to increased internal play and overheating.
8. Step-by-step elimination procedures
- Gear adjustment:
- Measure the actual backlash using a dial indicator. Compare with technical documentation (for example, 0.15-0.25 mm for module 5).
- Adjust the position of the shafts with the help of adjusting washers.
- Bearing replacement:
- Perform disassembly using specialized pullers. CAUTION: Do not apply shock loads to the new bearings during installation. Use the induction heating method (up to 90°C) to fit the inner ring onto the shaft.
9. Preventive measures
| The reason | Strategy | Method | Periodicity |
|---|---|---|---|
| Oil contamination | Filtration | Analysis by ISO 4406 | Quarterly |
| Overheating | Monitoring | Thermal imager | Every month |
| Uncenteredness | Centering | Laser tool | With every repair |
10. Spare parts
To order components, use the UNITEC-D E-Catalog:
| Description of the part | Specification | When to replace | Category UNITEC |
|---|---|---|---|
| Bearing | SKF/FAG are standardized | After 20,000 hours | Reducers-Bearings |
| Shaft seal | FKM (Viton) | When a leak is detected | Sealing |
| Olive | ISO VG 220 | Every 5,000 hours | Lubricating materials |
The full range is available at https://www.unitecd.com/e-catalog/
11. Links
- ISO 10816: Mechanical vibration - evaluation of the condition of machines.
- ISO 4406: Methods of coding the purity of working fluids.
- Technical documentation of the gearbox manufacturer (OEM).
