Abnormal noise and loud noise in the reducer are usually early warning signals of failure from the equipment. In order to avoid blind disassembly leading to damage expansion or increased repair costs, it is recommended to follow the scientific process of "judge first, then dismantle". You can quickly locate the fault location by following the following four steps:
Step One: Preliminary Investigation and Downtime Protection
Once you find that the reducer is making non-smooth and abnormal noises, you should immediately stop the operation of the equipment to prevent further deterioration of the fault. After the equipment has cooled down, first observe the appearance and check whether there are traces of oil leakage at the joints of the casing, the shaft extension end or the oil drain port, and whether the external connecting bolts are loose.
Step 2: Identify the root cause of the fault through "listening"
Damage to different components will emit sounds with different characteristics. This is the most direct method of locating:
Continuous "buzzing" sound or low roar: mostly caused by excessive bearing clearance, ball wear, or deformation of the inner and outer rings; it may also be caused by gear eccentricity, tooth surface gluing, or excessive meshing clearance.
Sharp "squeaking" sound or scratching sound: It is most likely due to poor lubrication (lack of oil or oil deterioration), resulting in direct metal friction between the gear and the bearing.
Rhythmic "clicking" or "clunking" sound: usually indicates broken gear teeth, severe wear, pitting corrosion on the tooth surface, or loose coupling, metal debris and other foreign matter inside.
High-frequency whistling sound: generally related to improper gear backlash or poor installation alignment.
Step 3: Accurate detection with professional tools
If it is difficult to determine based on hearing alone, the following methods can be used to assist in judgment:
Stethoscope positioning: Run the equipment without load, put the stethoscope close to the reducer housing (such as the position of the planet carrier, worm gear box or bearing seat) to accurately determine the specific source of abnormal noise.
Vibration and thermal imaging analysis: Use a vibration analyzer to measure the amplitude (normally should be ≤0.08mm). If the amplitude is >0.1mm or the body temperature exceeds 80°C, it means there is serious imbalance, bearing jamming or lubrication failure. The infrared thermal imager can also be used to detect whether there is an abnormal temperature difference in the bearing seat (temperature difference >8°C indicates uneven load).
Step 4: Disassembly, inspection and symptomatic repair
After locking the general range, the protective cover or shell can be removed for in-depth inspection:
Check the lubrication system: confirm whether the amount of oil is sufficient, whether the oil circuit is smooth, and whether the oil has deteriorated or been mixed. If necessary, clean the oil passage and replace the special lubricating oil according to standards.
Check the status of the gear: Use a dial indicator to detect the radial runout of the gear (>0.05mm needs to be adjusted), and measure the tooth thickness wear (the wear exceeds 10% of the original tooth thickness and needs to be replaced). Minor scratches can be polished with fine sandpaper. Severe wear or broken teeth must be replaced.
Check the bearings and assembly: Confirm whether the bearing is stuck or the raceway is peeled off, and make sure the clearance is appropriate during installation. At the same time, check the assembly clearance of the gear pair, use a laser alignment tool to calibrate the coaxiality of the input/output shaft (the deviation should be ≤0.05mm/m), and clean up any metal shavings or dust that may remain inside.
Post-Repair Verification Tip: Do not operate at full load directly after repair and reassembly. A no-load test run (about 30 minutes) should be carried out first. After confirming that the abnormal noise is completely eliminated, the equipment should be gradually loaded to the rated load in stages to ensure that the equipment resumes smooth operation.
