Selection of bearing type
Selection of bearing type
When selecting bearings, the main considerations are as follows:
The magnitude, direction and nature of the load on the bearing are the main factors for bearing selection.
When choosing the bearing according to the size of the load, compared with the point contact of the ball bearing, the main components in the roller bearing are line contact, which are easily used to bear the load, and the deformation after the bearing is small.
When bearings are chosen according to the load direction, thrust bearings are generally chosen for pure axial loads. The larger axial force is chosen for the thrust roller bearing. The smaller axial force chooses the thrust ball bearing. For pure radial loads, deep groove ball bearings, cylindrical roller bearings or needle roller bearings are usually selected. The deep groove ball bearing or tapered roller bearing can be chosen when the radial load is subjected to a small axial load, and the angular contact ball bearing or the tapered roller bearing can be selected when the axial load is larger. 
Rotating speed of bearing
In general, the rotation speed will not affect the selection of bearing type, but when the speed is larger, the speed should be included in the standard of bearing selection.
(1) compared with roller bearings, ball bearings have a higher limit speed, so the ball bearings should be given priority when the speed is high.
(2) in the case of the same inner diameter, the smaller the outer diameter, the smaller the rolling body, so the smaller the centrifugal force of the rolling body is added to the outer ring, so it is more suitable for working in the state of high speed. According to the properties given in Table 1, needle roller bearings are more suitable for working at high rotational speeds. 
The heart performance of the bearing
When the center line of the axle does not coincide with the center line of the bearing seat and has angle error, or when the axis is bending or tilting because of the force, the axis of the inner and outer ring of the bearing will be skewed. At this time, a self aligning bearing or an outer spherical spherical bearing with a certain centring function should be used.
Roller bearings are most sensitive to the deflection of bearings, and the bearing capacity of these bearings under skewed condition may be lower than that of ball bearings. Therefore, when the shaft stiffness and bearing hole support stiffness are low, or larger deflection torque, we should avoid using such bearings as far as possible. 
Bearing installation and disassembly
When the bearing seat has no dissection and must be installed and dismantled along the axis, the internal and external bearings (such as N0000, NA0000, 30000) should be preferred.
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