Rolling bearings are machine elements found in a wide field
of applications. They are reliable even under the toughest conditions
and premature failure is very rare.
The first sign of rolling bearing damage is primarily unusual
operating behaviour of the bearings. The examination of
damaged bearings reveals a wide and varied range of phenomena.
Inspection of the bearings alone is normally not enough to
pinpoint the cause of damage, but rather the inspection of the
mating parts, lubrication, and sealing as well as the operating
and environmental conditions.
Moving parts in machinery involve relative sliding or rolling motion. Examples
of relative motion are linear sliding motion, such as in machine tools, and rotation
motion, such as in motor vehicle wheels. Most bearings are used to support
rotating shafts in machines. Rubbing of two bodies that are loaded by a normal
force (in the direction normal to the contact area) generates energy losses by
friction and wear. Appropriate bearing design can minimize friction and wear as
well as early failure of machinery...
Finally, electromagnetic bearings involve complex design problems to ensure that the heavy spindle, with its high inertia, does not fall and damage the magnetic bearing when power is shut off or momentarily discontinued. Therefore, a noninterrupted power supply is required to operate the magnetic bearing, even at no load or at shutdown conditions of the system. In order to secure safe operation in case of accidental power failure or support of the rotor during shutdown of the machine, an auxiliary bearing is required. Rolling-element bearings with large clearance are commonly used.