The oil temperature of the ZQA500-31.5-7CA gear reducer exceeded 85°C during trial operation, which was an abnormally high temperature. It was necessary to stop the machine immediately for inspection and take systematic measures to control the temperature to avoid equipment damage. Combining the working conditions characteristics of this model and multi-source technical data, the treatment should be carried out step by step from emergency treatment, cause investigation to long-term optimization.
1. Immediate shutdown and safe cooling (emergency treatment)
Stop the machine immediately and cut off the power supply, and hang warning signs to prevent accidental startup.
Use an infrared thermometer to detect the temperature distribution on the surface of the box, focusing on monitoring the bearing seat, output shaft end and other parts. If the local temperature is close to or exceeds 90°C, wait for at least 30 minutes to naturally cool down before operating to avoid burns.
It is forbidden to spray water directly to cool down to prevent sudden cooling deformation of metal or seal failure.
An axial flow fan can be used to blow air onto the casing to assist in heat dissipation and improve cooling efficiency.
2. Systemic troubleshooting (locating the root cause)
1. Check the lubrication system
(1) Whether the oil level is appropriate: Check through the oil level mirror after stopping the machine for 10 minutes. The oil level should be near the center line. Too high will increase the stirring heat, and too low will result in insufficient lubrication.
(2) Whether the lubricating oil Selection matches:
It is recommended to use PAO synthetic gear oil or ester synthetic oil (such as L-CKD320/460) for ZQ series reducers under high temperature and high load. The viscosity index is >140 and the flash point is >260°C, which can effectively maintain high temperature oil film stability.
If mineral oil is used, it is prone to oxidation and deterioration at >80°C and needs to be replaced.
(3) Oil quality inspection: Observe whether it is black, turbid, precipitated or sour.
2. Check the heat dissipation conditions
(1) Ventilation environment: Ensure that there is no obstruction of ≥30cm around the reducer and a top space of ≥0.5m. If installed in a closed cabinet, a forced ventilation system must be installed (air changes ≥ 10 times/hour).
(2) Effectiveness of cooling device:
If air cooling is configured, check whether the fan is operating normally and whether the air duct is blocked by dust;
If it is water-cooled, check the temperature difference between the inlet and outlet water (normally 3–5°C) and whether the pipes are scaled or leaking.
(3) Case Cleaning: Clean the dust on the heat sink to improve the passive heat dissipation capability.
3. Load and operating status analysis
(1) During trial operation, the load should be controlled within the rated value. For every 10℃ increase, the load-bearing capacity decreases by 5%-8%, and long-term overloading will aggravate heating.
(2) To avoid frequent starts and stops or sudden load addition, it is recommended to use variable frequency soft start to extend the acceleration time to 15-20 seconds to reduce impact heat.
(3) No-load test: Disconnect the load operation, if the no-load oil temperature still rises rapidly, it means that the problem lies in the internal friction or heat dissipation system.
4. Mechanical condition inspection
(1) Bearing status: Turn the input shaft by hand to check whether there is any jamming or abnormal noise. A vibration meter can be used to detect the vibration speed. If it exceeds 4.5mm/s, further disassembly and inspection are required.
(2) Gear meshing accuracy: Measure the tooth backlash. If it is too small, it will cause 'tight meshing' heating.
(3) Use a laser alignment tool to check the radial deviation of the coupling. If it exceeds 0.1mm, it needs to be re-aligned.
