30.Magnetic bearings are used in applications where noise and vibration are important
considerations or where lubricants are not acceptable. Like the hydrostatic bearings they
do not require shaft rotation to generate bearing support forces. The rotor is floated in the
space and levitated by magnetic forces, which are generated within the bearing by
magnets. Therefore,
(A)the air is necessary to be used as the lubricant to provide the film pressure for magnetic
bearings.
(B)the air is necessary to be used as the lubricant to reduce the noise and vibration for
magnetic bearings.
(C)the shaft rotation is important for generating the supporting forces for the magnetic
bearings.
(D)the magnetic forces are generated in the magnetic bearing to support the load of
bearing.