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  • CLASSIFICATION NOTES

    NO. 41.2

    CALCULATION OF GEAR RATING FOR MARINE TRANSMISSIONS

    MAY2003

    DET NORSKE VERITAS Veritasveien l, N-1322 H0vik, Norway Tel.: +47 67 57 99 00 Fax: +47 67 57 99 l l

  • FOREWORD DET NORSKE VERJT AS is an autonomous and independent Fom1dation with the objective of safeguarding life, property and the environment at sea and ashore.

    DET NORSKE VERITAS AS is a fu1ly owned subsidiary Society of the Foundation. Tt undertakes classification and certifica-tion of ships, mobile offshore units, fixed offshore structures, facilities and systems for shipping and other industries. The So-ciety also carries out research and development associated with these functions.

    DET NORSKE VERTTAS operates a worldwide network of survey stations and is authorised by more than 120 national ad-ministrations to carry out surveys and, in most cases, issue certificates on their behalf.

    Classification Notes

    Classification Notes arc publications that give practical information on classification of ships and other objects. Examples of design solutions, calculation methods, specifications of test procedures, as well as acceptable repair methods for some compo-nents are given as interpretations of the more general rule requirements.

    A list of Classification Notes is found in the latest edition of the Introduction booklets to the "Rules for Classification of Ships", and the "Rules for Classification oflligh Speed, Light Craft and Naval Surface Craft". In "Rules for Classification of Fixed Offshore Installations", only those Classi lication Notes that are relevant for this type of structure, have been listed.

    The list of Classification Notes is also included in the current "Classification Services - Publications" issued by the Society, which is available on request. All publications may be ordered from lite Society's Web site http://cxchange.dnv.com.

    Provisions

    1t is assumed that the execution of the provisions of this Classification Note is entrusted to appropriately qualified and experienced people, fo r whose use it has been prepared.

    Det Norske Veritas 2003

    Data processed and typeset by Det Norskc Vcritas

    Printed in Norway 13/0812003 2:20 PM - CN4 I .2.doc If any peroon suffers loss or damage which is proved to have been caused by any oegrigenl act or omission of Del Norske Verilas. Lhen Det Norske Veritas shan pay compensation to such pen;on !C>r his proved direct loss or damage. However, the compensation shall not exceed an amount eQual to ten times the fee charged for the s&rvice in question. pn;vided that the maximum compensation shall never exceed USO 2 million. In this provision "Del Norske Veritas" shall mean the Foundation Det Norske Veritas as well as all ils subsidiaries, directors, officers, employees. agents and any olher acting on behalf of Del Norske Veritas.

  • CONTENTS

    1. 1.1 1.2 l.3 1.4

    1.5 1.6 1.6. l 1.6.2 1.6.3 1.7 1.7.1 1.7.2 1.8 1.8. l l.8.2 l.9 l.9.1 1.9.2 1.9.3 1.9 .4 1.9.5 1.9.6 1.9.7 1.9.8 1.9.9 1.10 1.11 1.12 2. 2.1 2.2 2.2.l 2.2.2 2.3 2.3. l 2.3.2 2.3.3 2.3.4 2.4 2.5 2.6 2.7 2.8

    2.9 2.10

    2.11 2.12 2.13 3. 3.1 3.2 3.2.1 3.2.2

    Basic Principles and General Influence Fact ors ... 4 Scope and Basic Principles ....... ................................ .4 Symbols, Nomenclature and Units .... ........................ 4 Geometrical Definitions ........ .... ........... .. .......... ....... ... 5 Bevel Gear Conversion Formulae and Specific Formulae ................................. ................................... 6 Nominal Tangential Load, F1, Fb Fmt and Fmhl .......... 6 Application Factors, KA and KAP ...... ......................... 7 KA ..................... ......................................................... 7 KAP ............................................................................. 7 Frequent overloads ...... ................ .. .... ... .... ...... .. ..... ..... 8 Load Sharing Factor, Ky ............................................ 8 General method ....... ... .. .. .... .. ......................... .......... ... 8 Simplified method ................ ..................................... 8 Dyna1nic Factor, Kv ...... .................................. ........... 8 Single resonance method ...... .. ........... ......... ........ ....... 8 Multi-resonance method .. ..................... ................ ... I 0 Face Load Factors, KHr1 and KFp ......................... ..... 10 Relations between KHri and Kt.-p ........................... ..... 10 Measurement of face load factors ................ ............ l 0 Theoretical determination of Ku11 ..... .... .................... l l Determination off.., .......................... ............ ........... 12 Determination offdefl ............ ...................... ........... 13 Dctcm1ination of fbe ................................................. 13 Determination of f.na ........ .... .... ................................ 13 Comments to various gear types ........................ .... .. 13 Determination ofKHp for bevel gears ...................... 13 Transversal Load Distribution Factors, K Hc. and Kpal4 Tooth Stiffness Constants, c' and Cy ............ .......... . . 14 Running-in Allowances ........................................... 15 Calculation of Surface Durability ......................... 17 Scope and General Remarks ... .. ........ ..... .. ..... ........... 17 Basic Equations ...................................... ................. 17 Contact stress ........................................................... 17 Permissible contact stress ......... ............. .................. 17 Zone Factors ZH, Zli,D and ZM .............................. .... 18 Zone factor ZH ............ ............ ..... ....... ......... ............ 18 Zone factors Za,l) ......................... ............................ I 8 Zone factor ZM ......................................................... 18 Inner contact point ................................................... 18 Elasticity Factor, Z ................................................. I 8 Contact Ratio Factor, Zc ........................................... 18 Helix Angle Factor, Zp ...................... ................ .. ..... 18 Bevel Gear Factor, ZK .... ......... ...... .. .... ........ ............. I 8 Values of Endurance Limit, crHiim and Static Strength, crH

    10s ,aH lO; ... ... .. ..... .. .. .. ........ . .. . . .. . .. ....... 18

    Life Factor, ZN .......................... .................. .......... ... 19 Influence Factors on Lubrication Film, ZL, Zv and ZR ........................................................ ... ..... ............. 19 Work Hardening Factor, Zw .................................... 20 Size Factor, Zx ............. ............................................ 20 Subsurface Fatigue ................................................... 20 Calculation of Tooth Strength .............................. 22 Scope and General Remarks .................................... 22 Tooth Root Stresses ............................. .................... 22 Local tooth root stress .. .... ................ ............. ....... .... 22 Permissible tooth root stress ......... .... ........ .... ....... .... 22

    3.3 3.3 .1 3.3 .2 3.4 3.5 3.6 3.7 3.8 3.8.1 3.8.2

    3.8.3

    3.8.4 3.8.5 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.15.1

    Tooth Form Factors Yr, Y Fa ........ .. ....... ... ......... .. ..... 23 Dctennination of parameters ................................... 23 Gearing with eun > 2 ................................................ 24 Stress Correction Factors Ys, Ys0 .. ............ .............. 24 Contact Ratio Factor Ye ........................................... 25 Helix Angle Factor Yp ............................................. 25 Values of Endurance Limit, PE ...... ........................ 25 Mean stress influence Factor, YM ............................ 26 for idlers, planets and PTO with ice class .............. 26 For gears with periodical change of rotational direction .................................................................. 26 For gears with shrinkage stresses and unidirectional load .. ............. ..... .. ... .. ..... ... ... .... ........... .......... .. ... ... ... 26 For shrink-fitted idlers and planets ........................ .. 26 Additional requirements for peak loads .................. 27 Life .factor, Y N ................................................. ..... .. 27 Relative Notch Sensitivity Factor, Yore\T ................. 28 Relative Surface Condition .factor, Y RreJT ............... 28 Size Factor, Y x ....................................... ................. 28 Case Depth Factor, Y c ............................................ 28 Thin rim factor Yu ................................................... 29 Slresses in Thin Rims .............................................. 29 General .................................................................... 29

    3 .15 .2 Stress concentration factors at the 7 5 tangents .. .... . 30 3.1 5.3 Nominal rim stresses ....................... ........................ 30 3. 15 .4 Root fillet stresses ........................................... ........ 30 3.16 Permissible Stresses in Thin Rims .......................... 31 3.16.1 General .................................................................... 31 3.16.2 For >3106 cycles ..................................................... 31 3.16.3 For S: 103 cycles ....................................................... 31 3.16.4 For l03

  • 4

    1. Basic Principles and General Intluence Factors

    t.l Scope and Basic Principles The gear rating procedures given in this Classi!ication Note arc mainly based on the IS0-6336 Part 1-5 (cylindrical gears), and partly on ISO 10300 Part 1-3 (bevel gears) and SO

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