1. Lubrication Methods and Applications
Gear reducers use either splash lubrication from an oil sump or forced circulation. Horizontal units at moderate speed usually rely on splash, with the rotating gears carrying oil to the mesh and bearings. High-power, vertical or high-speed units are better served by a pump-fed circuit with an oil cooler. The oil level line changes with mounting position, so fill according to the actual installation orientation.
2. Oil Selection and Fill Level
- Choose the viscosity grade of industrial gear oil by ambient temperature and tooth contact stress; use a lower grade in cold conditions.
- Fill to the centre of the sight glass: overfilling causes churning and oil loss through the breather, underfilling starves the mesh.
- Change oil after the first 200 to 300 hours, then set the interval by running hours and oil analysis.
3. Troubleshooting Abnormal Oil Temperature
If oil temperature stays above 80 degrees Celsius, first verify oil level and grade, then check the cooler for scaling or a blocked air path, and finally confirm that load has not exceeded the rating or that starting frequency is excessive. If temperature rise is accompanied by abnormal noise, stop the unit and inspect tooth contact pattern and bearing clearance to avoid scoring.
4. Routine Inspection Items
Observe the sight glass and breather every shift; check split faces and oil seals for seepage weekly; log oil temperature and vibration monthly; and sample oil periodically for water, viscosity and particle count. Seepage at the split face usually means aged sealant or uneven bolt torque; re-seal and tighten diagonally.
5. Practices That Extend Service Life
Keep the oil clean, avoid overload and maintain cooling and ventilation. For units on long standby, bar the shaft over periodically so that gears and bearings keep an oil film and start-up runs without dry friction.
6. Notes on Oil Changes
Drain while the unit is stopped but the oil is still warm, so suspended contamination leaves with the old oil. Clean the drain plug and magnetic plug and check for metallic particles. Fill through a filter cart or strainer to keep packaging debris out of the housing.
After refilling, run at no load for a short period and observe level, temperature and seepage before applying load. On vertical or inclined units, use the sight glass that corresponds to that mounting position rather than the horizontal reference value.
7. Three Routine Oil Analysis Indicators
Viscosity change indicates oxidation or contamination with another fluid; water content above limit destroys the oil film and promotes corrosion; rising particle count indicates increased wear or ingress of contamination. Record all three to distinguish an oil that has reached end of life from a machine fault.
- Change oil when viscosity falls outside the specified range and trace any mixing of grades.
- Investigate water content through cooler leakage and breather condition.
- Shorten the interval and inspect teeth and bearings when particle count keeps rising.
References
- GB/T 10095.1-2008 Cylindrical gears — ISO system of flank tolerance classification — Part 1: Definitions and allowable values of deviations
- GB/T 6404.1-2005 Acceptance code for gear units — Part 1: Test code for airborne sound
- GB/T 3480.1-2019 Calculation of load capacity of spur and helical gears — Part 1: Basic principles, introduction and general influence factors
- GB/T 7631.7-1995 Lubricants and related products (class L) — Classification — Part 7: Family C (gears)
