Gearbox Noise Troubleshooting

1. There is a bump on the tooth surface of the gear, causing the noise.

Situation: The sound frequency is stable, there is abnormal sound in one direction, and there is no abnormal sound in reverse rotation. The specific location of the abnormal sound can be determined by calculating the frequency relationship between the rotational speed of the low-speed shaft and the abnormal sound.

Cause: A bump occurred during assembly. Due to the flaws in the test quality control by the manufacturer, such a problem may occur in a very small number of gearboxes.

Treatment: According to the analysis results, look for the bumps on the tooth surface of the relevant gear carefully, and wipe the oil on the tooth surface to avoid affecting the feel. Bumps mainly exist on both sides of the tooth crest and tooth profile.

2. Excessive gear pitch error

Condition: The sound frequency is stable, and the two-way rotation is abnormal.

Reason: abnormal noise caused by the excessive change of adjacent tooth pitches caused by gear processing. The gear test report of the problem gear can be found by the ratio relationship.

Treatment: Except for the high-speed shaft that can be taken out, others cannot be dealt with, and can only be replaced and repaired.

3. Friction interference

Condition: The problem is more likely to occur in the maintenance workshop, the cranking does not move or is difficult to crank, and there is a friction sound during the test drive. The reason for the occurrence of the wind field is generally the interference between the oil throwing ring and the end cover, accompanied by abnormal heating of the relevant parts.

Treatment: Find the parts that interfere with friction, and rework or tighten the parts.

4. Bearings

Situation: When the sound frequency is fast, but the tooth surface inspection is normal, and the gear ratio relationship is used to calculate that it is not a problem of the gear, then it is very likely that there is a problem with the bearing.

Reason: There are dents on the inner ring raceway or roller surface of the bearing, which will cause the bearing to run unevenly and cause abnormal noise.

Treatment: Carefully check the bearing raceways and rollers, and replace the bearing if there is a problem.

5. Rust caused by gears not working for a long time

Condition: There is a long strip of corrosion marks on each of the two gears of a pair of gear pairs, and the remaining teeth are intact.

Reason: The gear box is parked for a long time, which causes the tooth surface to corrode, and the operation is not stable and produces abnormal noise.

Treatment: The rust cannot be completely eliminated, it can only be polished with oilstone first, and then look at the later changes.

6. other reasons

Condition: The sound appears near the spindle at the low-speed end or the brake disc at the high-speed end. After inspection, the parts of the gearbox are in good condition but there is still abnormal noise, or the frequency of the sound is not proportional to the rotational speed.

Reason: There may be a hub or spindle bearing problem at the low-speed end, and the high-speed segment may be caused by the alignment deviation of the coupling or motor.

Treatment: If the gearbox is repeatedly searched to confirm that there is no problem with the gearbox, it can be judged that there is a problem with other parts, and the professional gear motor manufacturer can be asked to search for the parts that may have problems.

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