The rolling sound of falling objects usually occurs in large bearings that are subjected to radial loads at low speeds. When the bearing operates under radial load, the load zone and non load zone inside the bearing. If the bearing has a certain radial clearance, the rolling element in the non load zone does not contact the inner raceway, but may come into contact with the outer ring due to centrifugal force. At low speeds, when the centrifugal force is less than the weight of the rolling element, the rolling element falls and collides with the inner raceway or cage, stimulating the inherent vibration and noise of the bearing.

And it has the following characteristics: it is also prone to occur when only radial loads are applied and the radial clearance is large. Within a specific range, bearings of different sizes may also have different speed ranges. It is easy to produce when lubricated with grease, but not easy to produce when lubricated with oil. It is more likely to occur when using inferior lubricating grease. It may be a continuous sound or an intermittent sound. It often occurs in winter.

This forced vibration often excites the second-order and third-order bending natural vibrations of the outer ring, thereby emitting this noise. The use of preloading method can effectively reduce the noise, reduce the radial clearance of bearings after installation, and use good lubricants to improve it. Some foreign companies use lightweight rolling elements, such as ceramic rollers or hollow rollers, to prevent the generation of this noise. The rolling element vibrates, and when the bearing operates under radial load, only if one of the rolling elements bears the load, the spring support formed by the elastic contact with the ring causes periodic vibration of the rolling element through the radial load line. As a result, the center of the shaft will move vertically or horizontally, causing noise. This type of vibration is called rolling through vibration, especially when operating at low speeds, which is more pronounced. And its amplitude is related to the type of bearing, radial load, radial clearance, and number of rolling elements. Usually, the amplitude is small, and only when the amplitude is large can it cause harm. Therefore, reducing the radial clearance or applying appropriate preload is often used to reduce it. The sharp sound is a quite intense scream generated by sliding friction between metals. Although the temperature rise of the bearing is not high at this time, it does not have much impact on the bearing life and lubricating grease life, nor does it affect rotation. However, the unpleasant sound is unsettling, especially for large short cylindrical roller bearings that bear radial loads.

The noise of the cage is generated by the free vibration of the cage during the rotation of the bearing and its collision with the rolling element or ring. It may appear in various types of bearings, but its sound pressure level is not too high and it is low-frequency. Its characteristic is that both thin oil and grease lubrication will occur. Both stamped and plastic cages can be produced. It is prone to occur when the radial clearance is large. It is most likely to occur when the outer ring is subjected to bending moment.

Due to the inevitable existence of clearance between the cage pocket hole and the cage and the ring in the finished bearing, it is very difficult to completely eliminate the cage noise. However, it can be improved by reducing assembly errors, optimizing reasonable clearance and cage displacement. Another type of cage noise is caused by the self-excited vibration of the cage caused by friction between the cage and the guide surface of other bearing components. The stamped cage of deep groove ball bearings is relatively thin, with low bending stiffness in the radial and axial planes, and poor overall stability. When the bearing rotates at high speed, it will generate self-excited vibration due to bending deformation, causing a buzzing sound.

When the bearing is subjected to radial load and the grease performance is poor, a clicking and clicking noise will be heard during the initial operation. This is mainly due to the noise emitted by the rolling element suddenly accelerating and colliding with the cage after leaving the load zone. This impact sound is inevitable but will disappear after a period of operation. The measures to prevent cage noise are as follows: When the bearing rotates at high speed, the vibration amplitude of the cage with a large pocket clearance is much greater than that of the cage with a small pocket clearance, so the value of the pocket clearance is particularly important. To ensure stable rotation of the cage, it is advisable to use ring guiding method as much as possible and pay attention to providing sufficient lubrication to the guiding surface. The structure of tapered roller bearings under high-speed working conditions should be improved by changing the L-shaped cage guided by the roller to the Z-shaped cage guided by the ring edge guard.

Pay attention to minimizing radial clearance as much as possible. Efforts should be made to improve the manufacturing accuracy and surface quality of the cage, which is beneficial for reducing the noise generated by collisions or friction between the rolling element and the cage. Actively adopting advanced cleaning techniques to effectively and thoroughly clean spare parts and assembled products, improving the cleanliness of bearings.