ISO INTERNATIONAL STANDARD 281 Second edition 2007-02-15 Rolling bearings Dynamic load ratings and rating life Roulements Charges dynamiques de base et duree nominale Reference number ISO 281:2007(E) @ ISO 2007 by IHS under lic Not for Resale ISO 281:2007(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF fle can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by IsO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. ?ISO2007 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, IsO's member body in the country of the requester. ISO copyright office Case postale 56. CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail [email protected] Web www.iso.org Published in Switzerland @ ISO 2007 - All rights reserved ted without licensefrom IHS Not for Resale ISO 281:2007(E) Contents Page Foreword. Introduction 1 Scope 2 Normative references 3 Terms and definitions. 4 Symbols. 5 Radial ball bearings .... 5.1 Basic dynamic radial load rating. 5.2 Dynamic equivalent radial load .. 9 5.3 Basic rating life ... 10 6 Thrust ball bearings... 10 6.1 Basic dynamic axial load rating, 10 6.2 Dynamic equivalent axial load.. 12 6.3 Basic rating life ..... 13 L Radial roller bearings .... 13 7.1 Basic dynamic radial load rating... 13 7.2 Dynamic equivalent radial load .... 15 7.3 Basic rating life ... 16 8 Thrustrollerbearings. 16 8.1 Basic dynamic axial load rating . 16 8.2 Dynamic equivalent axial load.. 19 8.3 Basic rating life .... 19 9 Modified rating life. .20 9.1 General.. 20 9.2 Life modification factor for reliability .... 9.3 Life modification factor for systems approach .21 Annex A (informative) Detailed method for estimating the contamination factor ... Annex B (informative) Calculation of the fatigue load limit ... Annex C (informative) Discontinuities in the calculation of basic dynamic load ratings.. Bibliography. Copyright International Organization for Standardizalon ghts reserved ii Not for Resale ISO 281:2007(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO member bodies). The work of preparing International Standards is normally carried out through ISO technicalcommittees.Eachmemberbodyinterestedinasubjectforwhichatechnicalcommitteehasbeer established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with isO, also take part in the work. IsO collaborates closely with the InternationalElectrotechnicalCommission(lEC)onallmattersofelectrotechnicalstandardization. International Standards are drafted in accordance with the rules given in the ISO/lEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. IsO shall not be held responsible for identifying any or all such patent rights. andlife. ISo 2007 - All rights reservec ional Organization for Standardizatior ISO 281:2007(E) Introduction thesuitability.Areliablelif