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ISO 281-1

1st Edition, March 15, 1977

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Rolling bearings - Dynamic load ratings and rating life - Part I: Calculation methods

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Superseded By: ISO 281

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This International Standard sets out methods of calculating the basic dynamic load rating and rating life of rolling bearings within the size ranges shown in the relevant IS0 publications, manufactured from good quality, hardened steel in accordance with good manufacturing practice and basically of conventional design as regards the shape of rolling contact surfaces.

This International Standard also specifies methods of calculating adjusted rating life to take into account various reliabilities, materials and operating conditions.

The present state of the art does not permit the inclusion in this International Standard of specifications such as, for example, that of the characteristics of good quality, hardened steel (analysis, inclusions, structure, hardness, etc.), or the inclusion of specific values of life adjustment factors for material and operating conditions. Revisions of this International Standard will therefore be required from time to time as the result of new developments or in the light of new information concerning specific bearing types.

Calculations according to this International Standard do not yield satisfactory results for bearings subjected to such application conditions and/or of such internal design which result in considerable truncation of the area of contact between the rolling elements and the ring raceways. Unmodified calculation results are thus not applicable, for example, to groove ball bearings with filling slots which project substantially into the ballhaceway contact area when the bearing is subjected to load in the application.

Calculations according to this International Standard do not yield satisfactory results for bearings subjected to such application conditions which cause deviations from a normal load distribution in the bearing, for example misalignment, housing or shaft deflection, rolling element centrifugal forces or other high speed effects, and preload or extra large clearance in radial bearings. Where there is reason to assume that such conditions prevail, the user should consult the bearing manufacturer for recommendations and evaluation of equivalent load and life.

This International Standard is not applicable to designs where the rolling elements operate directly on a shaft or housing surface, unless that surface is equivalent in all respects to the bearing ring (or washer) raceway it replaces.

Double row radial bearings and double direction thrust bearings are, when referred to in this International Standard, presumed to be symmetrical.

Further limitations concerning particular types of bearings are included in the relevant clauses.
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