Inspection before gear operation is a critical step to ensure the safe and efficient operation of equipment, effectively preventing failures, extending service life, and reducing maintenance costs. Below is a detailed inspection procedure and key points for gear operation readiness:
1. Visual Inspection
1.1 Gear Components
Tooth Surface Condition: Check for cracks, spalling, pitting, wear, or adhesive wear (scoring) on the tooth surfaces. Minor wear can be recorded and monitored, while severe damage requires gear replacement.
Tooth Profile Deformation: Observe whether the tooth profile is uniform and free from local deformation or bending, which may cause poor meshing.
Gear Shaft: Inspect the shaft for bending, cracks, or keyway wear, ensuring a tight fit between the shaft and gear.
Lubrication: Confirm sufficient lubricating oil or grease on the tooth surfaces to prevent dry friction, which can lead to overheating or wear.
1.2 Installation and Connections
Bolt Tightness: Verify that all bolts on the gearbox housing, end covers, and bearing seats are properly tightened to prevent loosening, which could cause vibration or leakage.
Alignment Accuracy: Use a dial indicator or laser alignment tool to check the alignment of gear shafts, ensuring parallelism or coaxiality is within the allowable range (typically ≤0.05 mm).
Key Connections: Ensure the key fits tightly in the keyway without gaps or looseness to prevent transmission slippage.
1.3 Surrounding Environment
Cleanliness: Remove dust, oil, or debris from inside and outside the gearbox to prevent foreign particles from entering the meshing area.
Protective Devices: Confirm that safety guards, oil baffles, and other protective devices are properly installed to prevent personnel contact or oil splashing.
2. Lubrication System Inspection
2.1 Lubricating Oil/Grease
Oil Level: Check the oil level via the oil sight glass or gauge, ensuring it is within the normal range (typically above the midpoint of the gauge).
Oil Quality: Observe the oil’s color, clarity, and odor. If the oil appears black, cloudy, or has a burnt smell, it may be oxidized or contaminated and requires replacement.
Viscosity: Select lubricating oil with the appropriate viscosity based on operating conditions (e.g., low-viscosity oil for high-speed gears, high-viscosity oil for heavy-load gears).
2.2 Lubrication Devices
Oil Pump: Verify that the oil pump operates normally and maintains stable oil pressure (typically 0.1–0.3 MPa).
Oil Lines: Ensure oil pipes are free from blockages or leaks and that oil nozzles or troughs are properly aligned with the meshing area.
Cooling System: If the gearbox is equipped with a cooling system (e.g., water or air cooling), check for unobstructed coolant/airflow.
3. Electrical and Control System Inspection (for electric gearboxes)
3.1 Motor
Wiring: Check that motor connections are secure and that insulation resistance meets requirements (typically ≥0.5 MΩ).
Rotation Direction: Confirm that the motor rotates in the correct direction as required by the gearbox to avoid reverse operation, which could cause damage.
No-Load Test: Start the motor briefly to observe smooth operation without abnormal noise or vibration.
3.2 Sensors and Protective Devices
Temperature Sensors: Verify that temperature probes are correctly installed and that alarm thresholds are set reasonably (typically ≤80°C).
Vibration Sensors: Ensure vibration monitoring systems are functional and that threshold values are appropriate (typically ≤5 mm/s).
Interlock Protection: Check that overload, overvoltage, and undervoltage protection devices are sensitive and reliable.
4. No-Load Trial Run Inspection
4.1 Initial Startup
Inching Test: Briefly jog the gearbox to observe smooth startup without jamming or impact.
Low-Speed Operation: Run at the minimum speed for 10–15 minutes to check for uniform gear meshing and normal noise levels (typically ≤85 dB).
4.2 Monitoring Parameters
Temperature: Monitor bearing and gearbox temperatures, ensuring they do not exceed ambient temperature by more than 40°C.
Vibration: Use a vibration analyzer to measure axial and radial vibration values, ensuring they are within allowable limits.
Oil Pressure: Confirm stable lubricating oil pressure without fluctuations or drops.
4.3 Post-Shutdown Inspection
Leakage: Check for oil leaks at all seals on the gearbox.
Looseness: Reconfirm that all bolts remain tight after vibration.
Abnormal Noise: Listen for unusual metal friction sounds inside the gearbox after shutdown.
5. Loaded Trial Run Inspection
5.1 Gradual Loading
Operate at 25%, 50%, 75%, and 100% load in stages, with each stage lasting at least 30 minutes while monitoring parameter changes.
5.2 Key Indicators
Noise: Noise under load should not increase significantly (typically ≤90 dB).
Efficiency: Check the ratio of input to output power to confirm transmission efficiency meets design requirements.
Temperature Rise: Ensure temperature rise under load is stable and does not exceed design limits (typically ≤70°C).
6. Documentation and Records
Inspection Checklist: Complete detailed inspection records, including items checked, results, corrective actions, and responsible personnel.
Historical Data: Compare with past inspection data to analyze gear wear trends and develop preventive maintenance plans.
Operating Manual: Ensure operators are familiar with gearbox startup, operation, and shutdown procedures.
Key Precautions
Safety First: Always disconnect power and hang a "Do Not Energize" sign during inspections.
Professional Tools: Use laser alignment tools, vibration analyzers, and other professional equipment for accurate inspections.
Regular Calibration: Periodically calibrate temperature, vibration, and other sensors to ensure data accuracy.