Why does a gearbox make noise

The gearbox is one of the key components in mechanical equipment. It transmits power through the meshing of gears. However, during the operation of the gearbox, the noise problem is a common phenomenon, especially after long-term use or when certain parts are worn. Noise not only affects the operation quality of the equipment but may also be a warning signal for certain potential failures. So, what are the reasons for the noise emitted by the gearbox? Next, we will provide a detailed interpretation from several common perspectives.

1.Gear wear or damage
Gears are the most core transmission components in a gearbox. They transmit power through mutual meshing. As time goes by, the tooth surfaces of gears will wear and even be damaged due to friction. This kind of wear will lead to unsteady meshing between gears, thereby causing vibration and noise.

Noise characteristics: The noise generated by gear wear is usually manifested as a periodic buzzing sound or a sharp friction sound, and the noise will increase as the speed of the gearbox increases.

Cause analysis: Gears are subject to continuous friction and impact during long-term use, which may lead to problems such as tooth profile wear and broken teeth; insufficient or improper lubrication will also exacerbate wear.

Solution:
①Check the wear condition of the gears and replace severely worn gears if necessary.
②Ensure there is sufficient lubrication inside the gearbox and replace the lubricating oil on time.

2.Bearing damage or aging
Bearings play a role in supporting the rotating shaft in the gearbox and reducing friction between gears. If the bearing is damaged or aged, the wear of the rolling elements or inner and outer rings will lead to instability inside the gearbox and generate abnormal vibrations, thereby causing noise.

Noise characteristics: When the bearing is damaged, the noise is often manifested as a metal friction sound or rolling sound, and sometimes accompanied by a sense of vibration.

Cause analysis: Bearings may be worn, stuck, or have balls fall off due to improper lubrication, overload, or long-term use, thus generating noise.

Solution:
①Regularly check and replace aged or damaged bearings.

②Ensure good lubrication of the bearings and avoid long-term operation under high temperature and high load.

3.Poor gear meshing
The meshing quality of gears directly affects the running smoothness of the gearbox. If the meshing angle between the gears is incorrect, or the meshing clearance is too large or too small, abnormal noise may occur when the gearbox is running.

Noise characteristics: Gears with poor meshing usually emit a sound similar to “buzzing” or “knocking”, and this sound is particularly obvious when the load is large.

Cause analysis: It may be due to improper installation of internal parts of the gearbox, deformation of the gearbox housing, or improper adjustment of the gear clearance.

Solution:
①Adjust the meshing clearance of the gears to ensure that it meets technical requirements.
②Regularly check and adjust the assembly state of the gearbox to avoid the influence of housing deformation on gear meshing.

4.Lubricating oil issues
The role of lubricating oil is to reduce friction between gears, reduce wear and take away heat. If there is insufficient lubricating oil, deteriorated lubricating oil or improper selection of lubricating oil type in the gearbox, excessive friction will occur during the operation of the gearbox, and then noise will be generated.

Noise characteristics: When the lubrication is poor, the noise is often a harsh friction sound, and the temperature of the gearbox will increase.

Cause analysis: Expired lubricating oil, containing impurities or insufficient oil quantity will cause direct contact between gears and bearings, aggravate wear and generate noise.

Solution:
①Regularly check the state of the lubricating oil and replace deteriorated or contaminated lubricating oil in time.
②Ensure sufficient oil quantity of the lubricating oil and select the lubricating oil type suitable for the working conditions of the gearbox.

5.Loose bolts or improper tightening
The parts inside the gearbox are fastened by bolts. If the bolts are loose, the internal parts will vibrate during operation and cause noise. At the same time, the loosening of structural parts such as the housing and fixed brackets may also cause vibration and noise.

Noise characteristics: The noise caused by loose bolts is usually manifested as vibration sound or knocking sound, and this noise may become more obvious when the equipment accelerates.

Cause analysis: Bolts become loose due to vibration or long-term use, causing the positions of parts such as gears and bearings to shift during operation, and then abnormal noise is generated.

Solution:
①Regularly check and tighten all bolts to ensure that the gearbox parts are stable and reliable.
②Use a torque wrench to tighten according to the specified torque to avoid being too loose or too tight.

6.Deformed or damaged housing
The housing of the gearbox not only plays a protective role but also provides stable structural support for internal parts. If the housing is deformed or damaged, the internal parts may lose the correct alignment state, resulting in increased friction between gears and bearings and emitting noise.

Noise characteristics: The noise caused by housing deformation is usually manifested as a low vibration sound or a similar “buzzing” noise, especially more obvious when the gearbox accelerates or decelerates.

Cause analysis: The housing is deformed due to external impact or long-term load-bearing, affecting the alignment and assembly accuracy of the internal parts of the gearbox.

Solution:
①Check whether the gearbox housing has obvious deformation or cracks. If it is damaged, replace it in time.
②Regularly check the fixing condition of the housing to ensure its firmness.

The noise problem of the gearbox is often a sign of some potential failure. From gear wear and bearing damage to lubricating oil problems and improper assembly, all can cause noise. Through regular maintenance, inspection and timely handling, we can prevent these noise problems and ensure the smoothness and safety of the gearbox during operation.