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Speeds
Lubrication
Despite using high quality roller bearing steel and using the most modern finish techniques, a roller bearing has a
finite service life.
This can be increased, under compliance with the optimum operating conditions, from the nominal service life up to
the extended modified service life. Since the service life calculations according to DIN ISO 281 in principle only take
the fatigue of the materials into consideration, as a consequence of design or technologically related deviations on
the relevant machine, e.g. owing to assembly errors or through wear of the parts, like seals, a premature limitation
of the functionality of the bearing can be expected. The end of operability is termed as the length of use
We recommend first to make an estimate of the heat balance at the bearing position and then to select a suitable lubrication
system. You may use grease or oil lubrication, but also solid lubrication is possible for special applications
The lubrication decisively influences the service life of the roller bearing. The relationships depicted with the standpoint
of the extended modified service life lead to the conclusion that with a proper selection and care of the lubricant,
if required, by choosing special additives, at least the length of use can be significantly increased as compared
with nominal service life. Especially with large bearings, which the speeds are low in owing to design limitations,
high-quality lubricants allow overloads up to the static load capacity.
The selection criteria for the lubricant are depicted in the Table Lubricants criteria - Selection criteria dargestellt.
A first indication of a lubricant‘s performance may be the lubrication factor d m · n. This factor is mainly used to characterize
the operating conditions in combination with the load ratio C/P. On this basis, e.g. the grease type may
be selected.
We recommend to consult with the vendors of lubricant brands, especially if additives are to be used. .
Lubricants criteria - Selection criteria
Vital design parameters Examples (alternatives and others)
Bearing type and design Cylindrical roller bearings with cage
Mounting position Horizontal (vertical)
Seals Labyrinth seal (contact seal)
Lubrication system Central lubrication (grease, expected lubrication life)
Vital design parameters
Load type Static, (dynamic, constant, impact type)
Ratio to the load rating
Type of motion Constant after start up (intermittently)
Speed Rotating inner ring with n = 1 rpm
Temperature Self-heating to approx. °C (external heating,
cooling by lubricant necessary)
Environment Splash water
Corroding media
Special criteria Noise
Safety regulations
To select the lubrication type, not only the place and position of the roller bearings to be installed are important, but
also the expected operating temperature. Operating temperature means mainly the temperature measurable on the
outer ring after a sufficiently long running time of the unit or machine (inertia temperature).
The expected operating temperature of selected installation cases is depicted in the Table Operating bearing temperatures
with selected applications.
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