The use of ball bearings is to determine the relative position of two parts (usually the shaft and bearing seat) and to ensure their free rotation and transfer the load between them. At a high speed (for example, in a gyro ball bearing), this use can be extended to include free rotation and almost no wear in the bearing. In order to achieve this state, a layer of adhesive fluid, called an elastic fluid dynamic lubrication film, is used to separate the two parts of the bearing. Deng Hudson (1966) pointed out that not only in the load bearing on the shaft, and the bearing preload and the positioning accuracy and stability of the shaft does not exceed 1 inches or 1 inches of micro nano, can maintain the elastohydrodynamic lubrication film .
Ball bearings are used in various machines and equipment with revolving parts. Designers often have to decide that ball bearings or fluid film bearings should be used in specific applications. The following features make ball bearings more desirable in many situations than fluid film bearings.
1. the starting friction is small and the working friction is suitable.
2. It can bear radial and axial joint loads.
8. is not sensitive to the interruption of lubrication.
4. no self-excited instability.
5. it is easy to start at low temperature.
In a reasonable range, the change of load, speed and working temperature have little effect on the good performance of the ball bearing.
The following characteristics make the ball bearing less than the fluid film bearing.
1. the finite fatigue life changes greatly.
2. of the required radial space is larger.
3. the damping capacity is low.
The level of I. noise is high. A.
The 6. pairs are more stringent.
6. the cost is high.
According to the above characteristics, the piston engine usually uses a fluid film bearing, while the jet engine is almost only ball bearings. Various types of bearings have their unique advantages. In a given application, the most suitable type of bearing should be carefully chosen. The British Engineering Science Data Organization (ESDU 1965, 1967) has provided useful guidelines for the important issue of selecting bearings.
Related Industry Knowledge