Machinery in supporting parts, plane needle roller bearings in radial, axial and circumferential (tangential) three directional position fixed by the different requirements. Under normal circumstances, FAG bearings axial axial fixation is used closed or sector realizes with the radial tight fit, institutions supporting the free side of the bearing on the shaft is not fixed, to compensate for the system to install the axis or in the process of expansion and contraction of the size changes.
　　1. support high precision, not working, and reliable.
　　2. under the environment of high temperature, cryogenic and vacuum operation.
　　3. the complex structure of requirements provided harsh environment magnetic interference, but not other forms of pollution.
　　4. friction small, low power consumption, ultra high-speed operation.
　　5. Gage-bearing only is active (active).
　　6. permanent magnetic-bearing-only passive (passive) and SKF bearings are not impossible in 3 directions, at least 1 source should be used.
　　7. repulsion of magnetic bearings, magnetic low utilization, a suction-type complex structure, rarely used.
　　8. pure magnetite-bearing-NSK bearings can only be 5 degrees of freedom control, volume, mass and power consumption are relatively large.