2. Falling body rolling sound
In general, this noise mostly occurs in large bearings at low speeds and bearing radial loads. When the bearing is running under radial load, the bearing's internal load area and non-load area, if the bearing has a certain radial clearance, the rolling body in the non-load area does not contact the inner raceway, but due to the effect of centrifugal force, For this reason, at low speeds, when the centrifugal force is less than the weight of the rolling body, the rolling body will fall and collide with the inner raceway or cage and excite the inherent vibration and noise of the bearing, and have the following characteristics:
a. It is easy to produce when grease lubricating, but not easy to produce when oil lubricating. It is more likely to occur when using inferior grease.
b. Winter often occurs.
c. It is also easy to occur when only radial load is applied and the radial clearance is large.
d. It will also be produced in a certain range and the speed range of different size bearings is also different.
e. May be continuous or intermittent.
f. The forced vibration often excites the second- and third-order bending natural vibrations of the outer ring, thereby emitting the noise. This noise can be effectively reduced by using the preload method, and the radial bearing clearance of the bearing after installation can be reduced. It can also be improved by using a good lubricant. Some foreign companies use light rolling elements such as ceramic rollers or hollow rollers. To prevent this kind of noise.