8/6/2019 Baearing Lubrication
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Bearing Lubrication
Key Words: Bearings; Lubrication; Intervals; Period; Generator;
Hydrogenerator; Turbogenerator;Tachogenerator; Induction;
Synchronous; Direct CurrentClassification: Information
Grease - Lubricated Bearings
The purpose of this maintenance is to lengthen bearing life
time. Weg motors are normally supplied with grease -lubricated ball
or roller bearings. Bearings should be lubricated to avoid metallic
contact of the moving parts, andalso for protection against
corrosion and wear. Lubricant properties deteriorate in the course
of time and due tomechanical operation and, furthermore, all
lubricants are subject to contamination under working conditions.
Forthis reason, lubricants must be renewed or replaced from time to
time.
l Lubrication Intervals
Lubrication intervals depend on the size of the motor/generator,
speed, working conditions, type of grease
used and working temperature. The lubrication period and type of
bearings are indicated on the motorgenerator dimensional drawing
and/or Data Sheet.
Correct lubrication is important for proper bearing operation.
It means to say the grease must be appliedcorrectly and in
sufficient amount. On the other hand, insufficient or excessive
greasing are prejudicial.Excessive greasing causes overheating due
to high resistance encountered by the rotating parts and,
inparticular, by the compacting of the lubricant and its eventual
loss of lubricating qualities. This can causeleakage with the
grease penetrating into the motor winding, commutator rings or
brushes.
Important: Never mix greases with different base components.
Example: Lithium base grease should never be mixed with other
types having sodium or calcium base. It is notrecommended to mix
different types of grease before contacting the grease supplier or
WEG.
Oil - Lubricated Sleeve Bearing
The oil change of the bearings must be effected every 8000
operating hours, or every time the oil modifies itscharacteristics.
Viscosity and oil pH must be checked periodically. Oil level must
be checked daily which must bekept approximately at the center of
the oil level sight glass. The bearing must be filled with the
prescribed type ofoil through the oil port after removing the pipe
plug. All holes and threads not used are to be closed by pipe
plugs.Also check all connections for oil leaks. Filling the bearing
with lubricant beyond the middie of the oil sight glassdoes not
impair the function of the bearing, but there is a possibility that
excess oil may leak out through the shaft
seals.
In case of circulating oil lubrication, the outlet connection
should be screwed into the threaded hole of the oil sightglass.
Cares taken with bearing lubrication will determine the life for
such bearings as well as the assurance of motoroperation. For this
reason, it is essential to follow these recommendations:
- The oil selected must have a viscosity suitable for the
bearing operating temperature. This must be checkedduring eventual
oil change or during periodical maintenances.
- If the bearing is filled with oil below the required oil
level, or if the oil level is not checked periodically,insufficient
lubrication may lead to damage to the bearing liner. The minimum
oil level is reached when the oilcan just be seen in the oil sight
glass when the machine is not in operation.
Type of oil, amount of grease and bearing type for each
motor/generator are given on the dimensional drawingand/or data
sheet.
