NES 305 Requirements for Gearing - Main Propulsion

Requirements for Gearing-Main Propulsion

Ministry of Defence Defence Standard 02-305

Issue 2 Publication Date 13 January 2003

Category 2

AMENDMENTS ISSUED SINCE PUBLICATION

AMD NO DATE OFISSUE

TEXT AFFECTED SIGNATURE &DATE

Revision Note

This Issue of this Standard has been prepared to incorporate changes to text and presentation.The technical content has been updated in line with current practice.

Historical Record

Def Stan 02-305 Issue 1 1 April 2000NES 305 DRAFT Issue 5 May 1998NES 305 Issue 4

1

DEFENCE STANDARD 02305 (NES 305)

REQUIREMENTS FOR GEARING MAIN PROPULSION

ISSUE 2

This Defence Standard is

authorized for use in MOD contracts

by the Defence Procurement Agency and

the Defence Logistics Organization

Published by:

UK Defence StandardizationDefence Procurement AgencyAn Executive Agency of The Ministry of DefenceKentigern House65 Brown StreetGlasgow G2 8EX

DEF STAN 02305 / ISSUE 2(NES 305 )

2

SCOPE

1. This Defence Standard (DEF STAN) 02-305, in conjunction with the documents referred toherein, specifies the minimum requirements which must be met by the Main Gearing Contractorand other authorities, during the design, manufacture, installation and commissioning of a MainPropulsion Gearbox intended for use in Vessels for the Royal Navy.

2. This Standard will be called into use by the contract placed on the Main Gearing Contractor todesign and/or manufacture a Gearbox. As this Standard also places responsibility on PrimeContractors or other manufacturing/installation authorities, it will also be called into use bycontracts concerned with the building of Vessels and Shore Test Facilities (STF).

3. The extent of the equipment covered by this Standard is as follows:

a. The Main Gearing, which comprises:

(1) The gearcase, and all gears, shafts (main and lay), oil seals, dipsticks, clutches, brakes,couplings and bearings contained therein;

(2) The input flexible coupling including control of the interface with prime mover outputflange and its satisfactory performance where applicable;

(3) The Gearbox output flange(s) and Main Shaft Flexible Coupling where applicable;

(4) The responsibility for the successful installation and commissioning of the high speedline(s), including balancing.

b. The lubricating system internal to the Gearbox downstream from the Gearbox supplypoint(s) (to be defined). For futher information and guidance refer to DEF STAN 02-303.

c. Gearbox Atmospheric Control:

(1) Venting;

(2) Dehumidification.

d. All local controls and surveillance instrumentation associated with the Main Gearing,including the local Plant Control Unit (PCU), if specified.

e. Auxiliary drives required by the System Requirement Document (SRD) as follows:

(1) For gear driven units mounted on the Gearcase or, when integral on the Drain Tank;

(2) For driven units mounted remotely, e.g. on the Vessels structure.

f. The Main Thrust Bearing, only if stated in the SRD. Requirements relating to the designand manufacture of Main Thrust Bearings are given in DEF STAN 02-304.

g. All other Gearbox auxiliaries (e.g. Turning Gear, Dehumidifier, etc.) required by thisStandard or by the SRD.

h. The electrotechnical equipment associated with the Gearbox (e.g. control and surveillanceinstrumentation) and with those items mounted directly on the Gearcase (e.g. Turning Gear)or, when integral, on the Drain Tank (e.g. Motor Driven Lubricating Oil (LO) pumps). Theterm Electrotechnical is formally defined in DEF STAN 08-107; it includes all items suchas motors, starters, junction boxes, cable conduit and wiring.

i. Gearbox seating arrangements.


3

FOREWORD

Sponsorship

1. This Defence Standard is sponsored by the Warship Support Agency (WSA), Ministry of Defence(MOD).

2. Any user of this Standard either within MOD or in industry may propose an amendment to it.Proposals for amendments that are not directly applicable to a particular contract are to be madeto the publishing authority identified on Page 1, and those directly applicable to a particularcontract are to be dealt with using contract procedures.

3. If it is found to be unsuitable for any particular requirement MOD is to be informed in writing ofthe circumstances.

4. No alteration is to be made to this Standard except by the issue of an authorized amendment.

5. Unless otherwise stated, reference in this Standard to approval, approved, authorized and similarterms, means by the MOD in writing.

6. Any significant amendments that may be made to this Standard at a later date will be indicated bya vertical sideline. Deletions will be indicated by 000 appearing at the end of the line interval.

7. This standard has been reissued to reflect changes in Departmental Nomenclature due to MODreorganization and the changes to technical requirements.

Conditions of Release

General

8. This Defence Standard has been devised solely for the use of the MOD, and its contractors in theexecution of contracts for the MOD. To the extent permitted by law, the MOD hereby excludes allliability whatsoever and howsoever arising (including but without limitation, liability resultingfrom negligence) for any loss or damage however caused when the Standard is used for any otherpurpose.

9. This document is Crown Copyright and the information herein may be subject to Crown or thirdparty rights. It is not to be released, reproduced or published without written permission of theMOD.

10. The Crown reserves the right to amend or modify the contents of this Standard without consultingor informing any holder.

MOD Tender or Contract Process

11. This Standard is the property of the Crown. Unless otherwise authorized in writing by the MODmust be returned on completion of the contract, or submission of the tender, in connection withwhich it is issued.

12. When this Standard is used in connection with a MOD tender or contract, the user is to ensure thathe is in possession of the appropriate version of each document, including related documents,relevant to each particular tender or contract. Enquiries in this connection may be made to theauthority named in the tender or contract.

13. When Defence Standards are incorporated into MOD contracts, users are responsible for theircorrect application and for complying with contractual and other statutory requirements.Compliance with a Defence Standard does not of itself confer immunity from legal obligations.


4

Categories of Defence Standard

14. The Category of this Standard has been determined using the following criteria:

a. Category 1. If not applied may have a Critical affect on the following:

Safety of the vessel, its complement or third parties.

Operational performance of the vessel, its systems or equipment.

b. Category 2. If not applied may have a Significant affect on the following:

Safety of the vessel, its complement or third parties.

Operational performance of the vessel, its systems or equipment.

Through life costs and support.

c. Category 3. If not applied may have a Minor affect on the following:

MOD best practice and fleet commonality.

Corporate experience and knowledge.

Current support practice.

Related Documents

15. In the tender and procurement processes the related documents listed in each section and AnnexA can be obtained as follows:

a. British Standards British Standards Institution,389 Chiswick High Road,London, W4 4AL

b. Defence Standards UK Defence StandardizationDefence Procurement AgencyAn Executive Agency of the Ministry of DefenceKentigern House65 Brown StreetGlasgow, G2 8EX.

c. Other documents Tender or Contract Sponsor to advise.

16. All applications to the MOD for related documents are to quote the relevant MOD Invitation toTender or Contract number and date, together with the sponsoring Directorate and the Tender orContract Sponsor.

17. Prime Contractors are responsible for supplying their subcontractors with relevant documentation,including specifications, standards and drawings.

Health and Safety

Warning

18. This Defence Standard may call for the use of processes, substances and/or procedures that areinjurious to health if adequate precautions are not taken. It refers only to technical suitability andin no way absolves either the supplier or the user from statutory obligations relating to health andsafety at any stage of manufacture or use. Where attention is drawn to hazards, those quoted maynot necessarily be exhaustive.

19. This Standard has been written and is to be used taking into account the policy stipulated in JSP430: MOD Ship Safety Management System Handbook.

Additional Information

20. (There is no relevant information included.)


5

CONTENTSPage No

TITLE PAGE 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SCOPE 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

FOREWORD 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Sponsorship 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Conditions of Release 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Categories of Defence Standard 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Related Documents 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Health and Safety 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Additional Information 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CONTENTS 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 1. PERFORMANCE SPECIFICATION 8. . . . . . . . . . . . . . . 1.1 Basic Requirements 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1.1 Design Objectives 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1.2 Design Basis 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 2. NATIONAL/INTERNATIONAL REGULATIONS 11. . . .

SECTION 3. MILITARY STANDARDS/REQUIREMENTS 11. . . . . . . . 3.1 Design Justification, Drawings and

Information Required 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.1 General 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.2 Design Justification Process 12. . . . . . . . . . . . . . . . . . . . . . . 3.1.2.1 Information Required 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.3 Drawings and Information Required in Support of a

Gearbox Tender 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.3.1 Information Required 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.4 Quality and Format 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.5 Drawings and Information Required for a

Design Contract or Gearbox Order 15. . . . . . . . . . . . . . . . . 3.1.5.1 Preliminary Design Information Required 15. . . . . . . . . . . Table 3.1 Information to be Supplied by Prime Contractor in

Support of a Design Contract 16. . . . . . . . . . . . . . . . . . . . . . 3.1.6 Final Design 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.6.1 Design Justification and Drawing Standards 17. . . . . . . . . 3.1.6.2 Information Required 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.6.3 Additional Information 193.1.6.4 Quality Assurance of the Design 20. . . . . . . . . . . . . . . . . . . . 3.2 Materials 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.1 Wheels and Pinions 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.2 Gearcases 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.3 Bearings 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


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3.2.4 Lubrication Suction, Delivery and Drain Pipework 21. . . . 3.2.5 Electrical Equipment 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.6 Rubber O Rings 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.7 Shafts and Couplings 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Gear Tooth Design 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.1 Helix Angle 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.2 Tooth Form 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.3 Tooth Load Distribution 22. . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.4 Tooth Loading Analysis 23. . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.5 Gear Element Safety Factors 23. . . . . . . . . . . . . . . . . . . . . . 3.3.6 Scuffing 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 Gear Construction 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.1 General 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.2 Gear Element Construction 24. . . . . . . . . . . . . . . . . . . . . . . 3.4.3 Accuracy 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.4 Identification 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 Gear Case Design 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5.1 General 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6 Lubrication and Venting 27. . . . . . . . . . . . . . . . . . . . . . . . . . 3.6.1 General 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.6.2 Lubrication 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7 Bearings 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.1 General 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.2 Steel Backings 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.3 White Metal Lining 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.4 Bearing Design and Analysis 29. . . . . . . . . . . . . . . . . . . . . . . 3.7.5 Oil Inlets 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.6 Housing 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.7 Fitting 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.8 Caps 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.9 Vibration Measurement 31. . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.10 Temperature Measurement 31. . . . . . . . . . . . . . . . . . . . . . . . 3.8 Turning Gear 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8.1 General 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9 Shafts and Couplings 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9.1 General 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9.2 Loose Couplings 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9.3 Oil Injections Loose Couplings 33. . . . . . . . . . . . . . . . . . . . . 3.9.4 Keyed Loose Couplings 34. . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9.5 Involute Splined Couplings 34. . . . . . . . . . . . . . . . . . . . . . . . 3.9.6 Justification of Alternative Designs 35. . . . . . . . . . . . . . . . . 3.9.7 Power Transmission 35. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9.8 Information to be Provided 35. . . . . . . . . . . . . . . . . . . . . . . . 3.10 Clutches 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11 Fasteners 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.11.1 Threaded Fasteners 37. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


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3.11.2 Non-Threaded Fasteners 38. . . . . . . . . . . . . . . . . . . . . . . . . . 3.12 Instrumentation 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.12.1 General 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.12.2 Local Control and Surveillance 40. . . . . . . . . . . . . . . . . . . . 3.12.3 Remote Control and Surveillance 40. . . . . . . . . . . . . . . . . . . 3.12.4 Design Constraints 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.13 Gearcase Manufacture 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.13.1 General 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.14 Balancing and Vibration 42. . . . . . . . . . . . . . . . . . . . . . . . . . 3.14.1 Balancing 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.14.2 Vibrations 43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.15 Inspection 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.15.1 General 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.15.2 Acceptance Standards 45. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.16 Shop Flushing 46. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.16.1 General 46. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.17 Cleanliness and Preservation 46. . . . . . . . . . . . . . . . . . . . . . 3.17.1 During Manufacture 46. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.17.2 After Shop Trials 46. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.17.3 Cleanliness and Preservation After Delivery 47. . . . . . . . . . 3.17.4 Cleanliness During Installation 47. . . . . . . . . . . . . . . . . . . . . 3.17.5 Preservation and Cleanliness up to Acceptance 48. . . . . . . 3.17.6 Preservation During Setting to Work 48. . . . . . . . . . . . . . 3.18 Testing 48. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.18.1 Shop Testing 48. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.18.2 Performance Testing of a New Gearbox Design 48. . . . . . . 3.18.3 Production Test 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.18.4 Post Test Inspections 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.18.5 Records Required During Tests 50. . . . . . . . . . . . . . . . . . . . 3.19 Contractor Sea Trials 51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.19.1 General 51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.19.2 Alignment 52. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.19.3 Records Required During Contractor Sea Trials 52. . . . . . 3.20 Records 52. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.20.1 General 52. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.20.2 Distribution 53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 4. DESIGN REQUIREMENTS/GUIDANCE 53. . . . . . . . . . .

SECTION 5. CORPORATE EXPERIENCE & KNOWLEDGE 53. . . . .

ANNEX A RELATED DOCUMENTS 54. . . . . . . . . . . . . . . . . . . . . . . .

ANNEX B ABBREVIATIONS AND DEFINITIONS 58. . . . . . . . . . . .

ANNEX C PROCUREMENT CHECK LIST 59. . . . . . . . . . . . . . . . . . .

ALPHABETICAL INDEX 61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


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1. PERFORMANCE SPECIFICATION

Related Documents: DEF STAN 02-304 Part 1; DEF STAN 08-123; BR 8470;see also Annex A.

1.1 Basic Requirements

1.1.1 Design Objectives

a. The design shall be based upon the following principles:

(1) Reliability: The achievement of adequate reliability is of overridingimportance in the design of Naval Gearboxes and no compromise of thisprinciple shall be made with any other requirement. As Main PropulsionGearing is not amenable to reliability prediction techniques a numericalreliability target will not be specified. However, a full reliability assessmentshall be required during the design as described in Clause 3.1. The Gearboxcontrols may be subject to a numerate reliability target which will be derivedfrom an assessment of the complete propulsion Plant Control System (PCS).The Gearbox manufacturer may be required to participate in suchassessments but will not normally be expected to lead them. Specificrequirements and targets shall be defined in the System RequirementDocument (SRD). Wherever possible reliability shall be obtained bydesigning equipment which is robust and simple;

(2) Maintainability: The Gearbox shall be designed for minimum maintenanceand for ease of such essential maintenance as is required. Experience hasshown that Gearbox reliability is often lowered rather than improved bymaintenance activities. The design should therefore incorporate facilities toease visual inspection so that the internal components are not disturbedexcept when faults are evident. The provisions made for maintenance shallbe reviewed throughout the design process as explained in Clause 3.1 and themanufacturer shall be required to co-operate in a Maintenance Evaluationexercise, which shall be conducted by Naval personnel on the first Gearboxproduced. The likely periodicity of major maintenance periods shall bedetailed in the SRD;

(3) Operation: The Gearbox shall be simple to operate and the controls shall bearranged so that no modes of operation can be achieved other than thoseintended by the designer. The Gearbox shall be suitable for both local andremote control and the siting of control levers, handwheels, instruments andgauges shall be such as to permit local operation by the minimum number ofpersonnel;

(4) Noise: Airborne and structure borne noise shall be minimized by adherenceto the specified accuracies and by designing the gear meshes for minimumtransmission error. Where specific noise and vibration targets have to be metthese shall be detailed in the SRD;

(5) Shock: This aspect shall be considered in both the layout and mounting ofcomponents and in the detailed design. (See Clause 1.1.2b(11)). Therequirements for resistance to underwater shock shall be detailed in the SRD;


9

(6) Accessibility:

(a) The design shall be within space limitations and provide the maximumaccessibility to gear parts which require routine examination,maintenance and repairs;

(b) Arrangements shall be made for access for examination andmaintenance without the necessity for disconnecting associatedpipework cables or any major components or assembly from theauxiliary unit. Pipes shall not be led through covers and doors;

(7) Standardization: The Gearbox shall be subject to refit/repair/overhaul byan upkeep by exchange policy. It is therefore essential that interchangeabilityis complete for all assemblies and components without the need for handfitting or machining or rearranging of electrical connections;

(8) Weight and Space: Specific limitations on weight and size shall be given inthe SRD. If no specific instructions pertain, weight and space shall be kept tothe minimum consistent with other requirements herein. The space requiredfor maintenance of the equipment shall also be minimized;

(9) Efficiency: Power losses shall be minimized for the normal operating range;

(10) Safety: Gearing designs shall embody the following safety features toprevent injury to operating and maintenance personnel in both normal andaction damage conditions:

(a) Moving parts of gearing such as Clutches, Brakes, Couplings, Gearelements, other than the main output shaft, shall be enclosed;

(b) Hand operating gear shall be interlocked or arranged to disengagewhen there is a possibility of power operation;

(c) Initial loads on spring assemblies shall be fully released before thespring is freed for dismantling.

1.1.2 Design Basis

a. The design shall be based on the following requirements unless specificinstructions to the contrary are provided in the SRD.

b. To Specifying Authority: It is essential that the requirements listed below, whichare based on typical past practice, are carefully examined for relevance to theparticular application for which this Standard is being used and that the PrimeContractor is informed of any changes considered necessary:

(1) Life: The design shall be based on the concept of infinite life with respect tofatigue stresses. Design shall be based on life expectancy of typically over150,000 hours of operation (this represents 25 years of life at 70 per centutilization per year). This shall include 5,000 hours at design Full Power and50,000 hours between 50 per cent and 100 per cent of design Full Power or asspecified in the SRD;

(2) Design Full Power: The power rating of the Gears shall be specified as themaximum continuous power requirement at the Gearbox input coupling(s);


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(3) Shaft Speeds and Gear Ratio: The required speed of the input and outputshaft shall be specified at the design Full Power condition with Vessels hulldeep and dirty. If, in selecting the number of teeth, it proves impractical toexactly match both speeds, the gear ratio may be varied by not more than onehalf per cent. The specified input speed and the actual Gear ratio shall then beused to define the design output shaft speed. The gear unit shall be capable ofcontinuously transmitting design Full Power at speeds up to 105 per cent ofthe specified input speed;

(4) Maximum Full Power Torque: The maximum full power torque is thatdeveloped when transmitting design Full Power at the specified input speed;

(5) Basis for Stress Calculations: Calculations of transmission loadings andstresses shall be based upon the specified input speed. Full Power centrifugalloadings and stresses, and calculations on whirling speeds shall be based on105 per cent specified input speed;

(6) Astern Operation: The Gearing shall be capable of transmitting 30 per centdesign Full Power in the astern direction at speeds up to 105 per cent of thespecified Full Power astern rpm;

(7) Thrusts: The Gearing shall be capable of withstanding such thrusts andmovements as are likely to be imposed by the Main Shafting. Thrust bearingdesign requirements are specified in DEF STAN 02-304 Part 1;

(8) Overload Capability: The design shall be capable of accepting thefollowing overloads without risk of damage:

(a) Torque: A non-transient ahead torque overload (duration of more thanthree seconds) of 125 per cent maximum Full Power torque in Steamand Diesel Installations and of 150 per cent maximum Full Powertorque in Gas Turbine installations. Torques up to these levels shalloccur during high power turns and rapid accelerations up to a total offive hours during the Ships life. Gears and shafts shall also be capableof withstanding 200 per cent of full power statically as might occur ifthe Propeller/Propulsor becomes jammed;

(b) Thrust: See DEF STAN 02-304 Part 1;

(c) Speed: An overspeed 15 per cent above the specified input speed;

(9) Manoeuvring:

(a) Reversing Gearboxes the frequency and times allowed for anynecessary manoeuvres shall be defined in the SRD;

(b) Non-reversing Gearboxes (i.e. those associated with ControllablePitch Propeller (CPP) or reversing prime movers) restrictions on thefrequency or timing of changes in the level or direction of torque andspeed would not normally be acceptable;

(10) Emergency Operation: The requirements for operation in other thannormal ahead and astern modes shall be specified separately;

(11) Shock Loads: All Naval Gearing shall be designed to withstand NavalShock Standard I, using procedure 1 of BR 8470;


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(12) Environmental Conditions: The gearing shall meet the requirements ofDEF STAN 08-123. The Gearing shall achieve the specified duty when theShip is in Extreme Tropical and Sub-Arctic (Winterization) conditions andshall be capable of safe continuous operation up to 70 per cent Full Powerunder Arctic conditions and under Closed Down conditions (ambienttemperatures may be derived from DEF STAN 08-123);

(13) Submersibility: Gearboxes shall be capable of operation in sea water for aspecified minimum duration and depth as quoted in the SRD;

(14) Cold Start: The Gearing shall be capable of transmitting up to 20 per centdesign Full Power with a Lubricating Oil (LO) inlet temperature of 5Celsiusand of transmitting 70 per cent design Full Power with a LO inlet temperatureof 20Celsius.

2. NATIONAL/INTERNATIONAL REGULATIONS

(No relevant information included)

3. MILITARY STANDARDS/REQUIREMENTS

See Annex A for a full list of all Related Documents.

3.1 Design Justification, Drawings and Information Required

3.1.1 General

a. This section describes the process by which the Prime Contractor shall control thedesign of the main gearing and identifies the programmes, drawings and otherdocumentation which shall be supplied. This section incorporates the followingsub-headings:

(1) Design Justification Process:

(a) Information Required (see Clauses 3.1.2.1a. 3.1.2.1d.);

(2) Drawings and Information Required in Support of a Gearbox Tender:

(a) Information Required (see Clause 3.1.3.1a.);

(b) Quality and Format (see Clause 3.1.4a.);

(3) Drawings and Information Required for a Design Contract or GearboxOrder:

(a) Preliminary Design:

(i) Information Required (see Clause 3.1.5.1(a);

(b) Final Design:

(i) Design Justification and Drawings Standards(see Clause 3.1.6.1);

(ii) Information Required (see Clause 3.1.6.2);


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(iii) Additional Information (see Clause 3.1.6.3);

(iv) Quality Assurance of the Design (see Clause 3.1.6.4).

3.1.2 Design Justification Process

3.1.2.1 Information Required

a. The Prime Contractor shall provide a design justification to demonstrate that allnecessary work has been undertaken during the design process to ensure that:

(1) All the requirements of the SRD and of this Standard have been or shall bemet;

(2) All potential sources of unreliability have been identified and their optimumelimination means determined;

(3) Proper account has been taken of the need to operate, maintain and supportthe Main Gearing throughout its working life at the lowest through-life cost.

b. As the first step is providing the assurance required by Clause 3.1.2.1a., the PrimeContractor shall establish a formal system to control the design process. Thissystem shall include the following elements:

(1) A formal record of the loads and movements assumed to be applied to theGearbox by its service environment, taking account of the most adverseconditions likely to occur;

(2) A means of defining the Gearbox in terms of assemblies, sub-assemblies andcomponents and for identifying the interfaces between them. (This mayconveniently be accomplished by means of the Functional Block Diagram(see Clause 3.1.6.2a.(5));

(3) A comprehensive list of possible failure modes considered for eachcomponent, assembly and sub-assembly;

(4) A formal assessment of these failure modes to determine and record whatassurance shall be provided against them. The form of assurance selectedshould take account of the risk and significance of the failure and the effortrequired to provide such assurance;

(5) A statement of the calculation method and acceptance criteria used for eachfailure mode to be checked by calculation;

(6) Methods for calculating or estimating the forces and/or movements likely tobe encountered by each component, sub-assembly and assembly within theGearbox;

(7) A means for recording that calculated and allowable values have beencompared and found acceptable;

(8) A means for ensuring that appropriate calculations are repeated if anychanges are made to the design or to external conditions.

c. Objective evidence of the systems effectiveness shall be provided by:

(1) Describing the system to be applied to each design;


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(2) Requiring the gear manufacturer to justify the list derived from Clauses3.1.2.1b. (1), (2), (3), (4) and (5);

(3) Conducting a series of formal Design Reviews which shall progressivelyapprove the design. The number and timing of these reviews may vary fromone design to another and a specific Design Justification Programme shall beagreed during the preliminary design phase.

d. The Prime Contractor shall submit a plan, prepared in accordance withDEF STAN 00-40 Part 1, showing which activities shall be undertaken to ensurethat the proposed design meets the requirements of DEF STAN 08-141Parts 1 and 2. Arrangements for monitoring these activities shall be included in theDesign Justification Programme.

3.1.3 Drawings and Information Required in Support of a Gearbox Tender


a. The Prime Contractor shall supply the following in respect of each gearing designsubmitted for consideration by the MOD:(1) General Arrangement of the machinery and/or system including sufficient

cross-sectional drawings to give an appreciation of the design andconstruction;

(2) An outline sectional arrangement of the Gear trains;(3) A statement giving Gearing particulars, including numbers of teeth,

reference circle, addendum and root circle diameters, pressure and helixangles, modules, face widths, strengths and pitting load rating calculationsusing BS ISO 6336-1, BS ISO 6336-2, BS ISO 6336-3 and/or BS ISO6336-5; as applicable. An assessment statement of the likelihood of damagedue to scuffing (using at least two different methods) and stating the methodsused shall also be submitted;NOTE For calculations using BS 436-3 it is acceptable at the tendering

stages to use estimates for load correction factors, however, theestimated values used shall be stated.

(4) A statement on the manufacturing and measuring techniques that shall beadopted for all Gear elements in order to satisfy the requirements stated in theSRD;

(5) A mass elastic diagram giving details of Gearbox inertia stiffness;(6) Details of any brake including the capacity of the unit in terms of total

absorbed energy, peak energy input rate, static holding torque and dynamicbraking torque compared with the maximum duty estimated for the particularapplication;

(7) Details of any Clutches, including power requirements, control signals andmaximum torque capabilities;

(8) Details of the Flexible Couplings, including Main Shaft Couplings, whereapplicable, shall include the misalignment capability under continuousrunning and shock. The anticipated misalignment shall be quoted;

(9) A control diagram showing the method of control proposed for the Brakes,Clutches, Couplings and Turning Gear and the interlocks between them;

(10) Position and size of mountings;(11) Estimated dry weight of all equipment covered by the tender. Estimated

weight of fluids in the unit at the normal working level;


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(12) Diagram of LO distribution arrangement including the calculated design oilflow and the corresponding bulk oil temperature rise at Full Power. Thesecalculations shall be based on normal running conditions;

(13) A statement of Gearing efficiency at maximum Full Power;(14) Main unit Journal Bearing loads and directions and a statement giving

principal bearing particulars, which shall include length, diameter, specificbearing pressure, rubbing speed, minimum oil film thickness, maximum oiltemperatures, oil temperature rise through the Bearing and bearing powerlosses. If rolling contact bearings are proposed, then a statement is requiredgiving the manufacturer, his serial number, a notation of where specialbearings are specified, the maximum loads, static and dynamic capacity,maximum speed and L10 life calculated for a specific power spectrum. ForThrust Bearings the information required by Clauses 3.7.4b, c. and d.inclusive shall be submitted;

(15) A statement on the maintenance requirements including services andmaintenance envelope of the Gearbox and, if appropriate, a description andsketch of the methods proposed for repair by replacement;

(16) A statement on the methods that shall be used for inspecting all Gearingelements, components and Bearings;

(17) A statement on the Running-in requirements for the Gearbox;(18) A programme and procedures for both shop testing and Contractor Sea Trials

(CST);(19) A list of spare parts or whole assemblies which shall be retained by the

manufacturer during build;(20) A detailed statement on the design philosophy used to minimize noise,

including such justification as does exist for any claims made about therelative noise performance of different design features, e.g. single versusdouble Helical Gears;

(21) A functional block diagram, identifying the functional arrangements andsignal flow paths inside the Gearbox and showing all external services orsignals entering or leaving the Gearbox. The diagram shall be presented as aleft-to-right flow diagram;

(22) A preliminary reliability assessment explaining how it is intended todemonstrate design-for-life aspects and reliability;

(23) The following estimates of timescales are required:(a) Time required from receipt of contract to the delivery of the first

Gearbox to the Vessel or Shore Test Facility (STF);(b) Maximum rate of production of subsequent Gearboxes;(c) A programme for the detailed design and manufacture of the STF

and/or first Vessel Gearboxes. Programme to include order dates for alllong lead items.

3.1.4 Quality and Format

a. Quality and Format requirements are that:(1) The tender submission should normally be in the form required by the tender

document;

(2) Drawings submitted with the tender shall meet the requirements ofDEF STAN 02-722.


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3.1.5 Drawings and Information Required for a Design Contract or Gearbox Order

3.1.5.1 Preliminary Design Information Required

a. The information required to be supplied as part of the design contract is listed inTable 3.1. The following paragraphs define the requirements in more detail anddefine the standards to which the work shall be carried out.

b. On receipt of the contract, the Prime Contractor shall prepare or revise the technicalportion of the submission report (see Clause 3.1.2b.) in accordance with the latestschedule or SRD. The prime Contractor shall supply the following information forreview by the MOD:

(1) An estimate of the polar moment of inertia and flexibility characteristics ofall rotating elements in the transmission;

(2) The calculation sheets relating to the design of all shafts and shaftconnections in the main transmission path showing allowable and actualmaterial stresses;

(3) A tabular statement on the safety factors under shock, relative to thepermissible shock stresses, in all shafts, shaft bolts, Bearing Cap bolts, and inthe Gearcase structure. Attention should be drawn to any items which haverequired additional strengthening to meet the shock duty;

(4) A detailed summary of the logistic requirements of the design such as LO andHydraulic Oil types quoting the various tank maximum and working levels;

(5) A schedule of the active electrotechnical equipment, with parameters thatshall be monitored and signalled, shall be proposed by the manufacture type,number etc., (e.g. pressure transducer, amplifier for speed probe, stateswitch, solenoid, motor, starter, etc.).

NOTE The Prime Contractor shall ensure that the requirements ofDEF STAN 02-54 shall be invoked at this stage.

c. The Gear manufacturer shall submit the following information:

(1) A preliminary Functional Block Diagram showing functional relationshipswithin the Gearbox and between the Gearbox and the rest of the Vessel. Thediagram shall indicate the limits of supply under the terms of the designcontract;

(2) A set of preliminary drawings showing the basis for design. If any of thesepreliminary drawings shall be updated to final design drawings, therequirements of DEF STAN 02-722 shall be observed;

(3) A detailed design programme showing the expected delivery dates for all theitems of design information listed in Table 3.1, Sections 2 and 3;

(4) A Reliability and Maintainability programme plan showing the activitieswhich shall be undertaken during the design and in accordance withDEF STAN 00-40 Part 1;

(5) A draft Design Justification Programme proposing dates for the FormalDesign Reviews and Design progress monitoring meetings;

(6) A list of all assemblies, sub-assemblies and components to assist the PrimeContractor in specifying the Upkeep Codes (see DEF STAN 07-200).


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LineNo

DescriptionReference

Clause

1 PRELIMINARY DESIGNThe following items shall be submitted for Project Authority approval beforestarting detail design. The date by which submission is required shall bespecified in the Design Contract:

1.1 Updated Tender Report; 3.1.5.1b.

1.2 Preliminary Functional Block Diagram; 3.1.5.1c.(1)

1.3 Additional drawings; 3.1.5.1c.(2)

1.4 A design programme showing the expected delivery dates of the informationlisted at 2 and 3 below;

3.1.5.1c.(3)

2 DESIGN DRAWINGS AND INFORMATIONThe following items shall be submitted to the Prime Contractor in accordancewith an agreed programme:

2.1 A suitably indexed Comprehensive Drawing Schedule; 3.1.6.2a.(1)

2.2 A twoway crossreferencing index between Manufacturer's Drawing Numbersand Service Drawing Numbers;

3.1.6.2a.(3)

2.3 One copy of all drawings required to manufacture the Gearbox, in a format tobe agreed with the MOD (e.g. microfilm/CD ROM);

3.1.6.2a.(4)

2.4 A full functional block diagram; 3.1.6.2a.(5)

2.5 A full set of physical interface drawings; 3.1.6.2a.(6)

2.6 A full set of signal/interface specification sheets identifying all signals and theirrelevant interfaces with the rest of the Vessel;

3.1.6.2a.(7)

2.7 A list of all external services required by the Gearbox; 3.1.6.2a.(8)

2.8 A list of and drawing of all jigs, fixtures, special tools and equipment requiredto install and maintain the Gearbox;

3.1.6.2a.(9)

2.9 A statement on the operating limitations for the Gearbox, covering all modesof operation;

2.10 A comprehensive Maintenance Schedule for the Gearbox; 3.1.6.2a.(10)

2.11 A detailed set of Maintenance Envelope drawings; 3.1.6.2a.(11)

2.12 Production Backup Spares; 3.1.6.2a.(12)

2.13 Spares Recommendation; 3.1.6.2a.(13)

2.14 A tabular statement on external loads and movements; 3.1.6.2a.(14)

2.15 A Reliability and Maintainability Report. 3.1.6.2a.(16)

3 ADDITIONAL DRAWINGS AND INFORMATIONThe following additional items shall be supplied to the Project Authority inaccordance with an agreed Schedule:

3.1 One `As Made' process master of each Datum Pack Drawing; 3.1.6.3a.(1)

3.2 One `As Made' process master of specified additional drawings required by thePrime Contractor;

3.1.6.3a.(2)

3.3 A loose leaf report containing all information required by the Shipbuilder orSTF Authority;

3.1.6.3a.(3)

3.4 Where called for in the contract, copies of all drawings, specifications, etc.,necessary for an alternative contractor to manufacture the Gearbox.

3.1.6.3a.(5)

Table 3.1 Information to be Supplied by Prime Contractor in Support of a Design Contract


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3.1.6 Final Design

3.1.6.1 Design Justification and Drawing Standards

a. Work on the final design of the Gearbox shall not commence until the basis for thedesign has been reviewed by the MOD in the form of the Preliminary DesignInformation as listed in Table 3.1.

b. All manufacturing drawings, electrical drawings, Datum Pack and other ProcessMasters shall conform to the requirements of DEF STAN 02-722.


a. The Prime Contractor shall supply the following information on the final design ofthe Gearbox:

(1) Comprehensive Drawing Schedule and Index: A suitably indexedComprehensive Drawing Schedule shall be provided to the MOD. Thisdocument shall itemize all the production drawings required to manufacturethe Gearbox plus all the drawings in the Datum Pack which are notproduction drawings. It shall be presented in assembly and sub-assemblygroups. The document will finally be used as a comprehensive accessdocument to the production prints held by the MOD;

(2) Although no attempt is made to quantify the mechanical equipment drawingsrequired to manufacture the Gearbox, in the case of electrotechnicalequipment in the Gearbox the following drawings shall be provided:

(a) Circuit Diagram;

(b) Wiring Diagram;

(c) Topographical drawing of the electrotechnical equipment inside andoutside the Gearbox;

(d) Schedule of all electrotechnical equipment active, as in Clause3.1.5.1b.(5), and passive (e.g. junction boxes, solid conduit, flexibleconduit, cable, etc.);

(e) Connection Diagram for all junction boxes, control panels, etc.;

(3) Drawing Number Cross-Reference: A two-way cross-referencing indexbetween gear Manufacturers Drawing Numbers and Service DrawingNumbers;

(4) Manufacturing Drawings and Setting to Work Procedures: One copy ofall drawings required to manufacture the Gearbox in a format to be agreedwith the MOD (e.g. microfilm, CD-ROM, etc.) and any information requiredto set the Gearbox to work (e.g. alignment or balancing procedures, boltingdown and levelling procedures);

(5) Functional Block Diagram: The preliminary Functional Block Diagramprovided under Clause 3.1.5.1c.(1) as expanded and updated by the designapproval process shall be redrawn to the datum pack standard (see Clause3.1.6.1b.);

(6) Physical Interface Drawings: A General Arrangement of the Gearbox,marked up to show the position of all physical interfaces shall be provided;


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(7) Signal Interface Specification Sheets: The physical and functionalproperties of each interface between the Gearbox and the rest of the Vesselshall be defined on a Signal Interface Specification Sheet. Each signalinterface shall be identified with regard to the Functional Block Diagramand/or Physical Interface Drawings. The Specification sheet shall provide across-reference to the manufacturers own detailed drawings of the interfaceand to any drawings produced by other contractors which are known to theGearbox manufacturer. It shall also show the limit of Gearboxmanufacturers supply;

(8) External Services: A list of external services required by the Gearbox. Theitems shall be cross-referenced with Clause 3.1.6.2a.(7);

(9) Jigs and Special Equipment: A list and drawings of all jigs, fixtures,special tools and equipment required to install and maintain the Gearbox;

(10) Maintenance Schedule: A Maintenance Schedule indicating the degree andperiodicity of maintenance required during the following periods:(a) In store prior to installation;(b) Installed in a vessel prior to Setting to Work (STW);(c) Operational;(d) During refitting;

(11) Maintenance Envelope: A drawing or drawings to meet the requirements ofDEF STAN 02-302 Part 1 and/or DEF STAN 08-103 Part 2, as applicable,which show and identifies the purpose of individual portions of theenvelopes, as follows:(a) The overall dimensions and chain dotted outline of the maintenance

envelope;(b) The operational area of the envelope. This area shall be highlighted;(c) Areas where access is only required for painting and preservation;(d) All withdrawal spaces for sub-assemblies, etc.;(e) Space required for access by lifting gear, transport devices, etc.;

(12) Production Back-up Spares: A list of parts or whole assemblies which areretained by the manufacturer during build;

(13) Spares Recommendation: A recommendation for general spares supportcovering the following:(a) On-board spare (First Category Spares);(b) Back-up spares for two-year period (Second Category Spares);(c) Spares for reconditioning equipment (Third Category Spares);(d) Spares for shelf-life maintenance, etc.;NOTE Method of initiating action on spares is contained in DEF STAN

02-54.(14) External Loads and Movements: A tabular statement on the loads and

movements assumed to be imposed on the Gearing from external sources;(15) Thrust Block: (Where fitted within the Gearbox). The righting moment,

running misalignment curve based on the expected maximum thrust and themaximum allowable righting moment based on the highest loaded padpressure;

(16) Reliability and Maintainability (R and M) Report: The report shall showthe results of the R and M plan agreed during the preliminary design stage(see Clause 3.1.5.1c.);


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(17) Dynamic Analysis of the High Speed Line(s): Details of the vibrationcharacteristics of the input lines, including the Prime Mover.

3.1.6.3 Additional Information

a. Certain additional information as listed in Table 3.1 shall be supplied before thefirst equipment is delivered. The detailed requirements are as follows:

(1) Datum Pack: The Datum Pack is a comprehensive set of drawings whichdefine the mandatory aspects of the Vessels design. It is used to control thebuild of follow-on Vessels and a microfilm copy, at the relevant state ofamendment, shall be supplied with each Vessel as a record of the design towhich it was built. It shall be progressively updated as significant changesare made to the class or to individual Vessel. After discussion with the PrimeContractor, the manufacturer shall submit a proposed list of drawings forinclusion in the Datum Pack. One As Made process master of each DatumPack drawing shall be supplied to the MOD at least one month before the firstVessels Gearbox is delivered. Datum Pack drawings shall conform fully tothe requirements of DEF STAN 02-722;

(2) Additional Process Masters: In addition to the Datum Pack, themanufacturer shall submit one As Made process master of additional majordrawings required by the Prime Contractor. A list of such drawings shall beprovided when the Datum Pack contents are approved. These drawings shallbe of the same quality and format as the Datum Pack drawings;

(3) Information to Prime Contractor: The Gearbox manufacturer shallprovide the Prime Contractor with a loose leaf report in respect of eachGearbox containing all the information required by the shipbuilder to install,set to work, operate and maintain the Gearbox. This report shall be passed tothe Prime Contractor at the time of the delivery of each Gearbox to theshipyard. The report shall contain at least the following items of information:

(a) Detailed definition of terminal points and interfaces (see Note 1);

(b) Requirements for and terminal points of all services;

(c) A list of special tools, facilities and equipment required to lift, transportand install the Gearbox;

(d) Installation instructions, including limitations relating to input andoutput shaft alignment (see Note 2) and the following information:

(i) Detailed drawing of the Main Wheel Shaft;

(ii) Detailed drawing of the Main Wheel;

(iii) Weights of the Main Wheel and Shaft;

(iv) Clearances at the Main Wheel Bearings;

(v) Thermal growth of the Gearbox;

(vi) Shaft attitude in Bearings;

(vii) Axial clearances of input and output Shafts;

(viii) Direction of load on Main Wheel;

(e) A list of precautions and/or special requirements that shall be met whenSTW;


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(f) A statement on the operating limitations which shall apply up toacceptance;

(g) A statement on the Gearbox maintenance required up to completion ofthe Basin Trial (see Note 3);

(h) A statement on which items of work the Gearbox manufacturer wouldrequire to perform himself during the guarantee period;

NOTE 1. This and subsequent requirements may be met by cross-reference tothe appropriate Gearbox, Prime Contractors drawing or otherauthorized document. It is essential that the date and issue numberof the relevant document is quoted.

2. The Prime Contractor is responsible for writing the installationinstructions and alignment procedures. The Gearbox manufactureris responsible for defining any limitations or constraints which shallbe observed and for approving the target tolerances and methodsproposed by the alignment procedure. The minimum requirementfor this report shall be a detailed cross-reference to the PrimeContractors installation and alignment procedures which have beenaccepted by the Gearbox manufacturer. Issue numbers shall bequoted.

3. After the basin trial the Prime Contractor shall maintain the Gearboxin accordance with the Maintenance Schedule referred to at Clause3.1.6.2a.(10).

4. Each page of the report shall be marked with a date and issue number.The status of each page (e.g. Original, Amendment 1, 2 or 3, etc.)shall be shown at the front of the report.

(4) Control of Design Changes:(a) Alteration State Zero: At the end of the detailed design stage the

manufacturer shall propose Alteration State Zero definition. Anysubsequent changes shall be termed Alterations and shall besequentially numbered and recorded for approval by the PrimeContractor;

(b) Modification State Zero: One month before the first VesselsGearbox is delivered, Modification State Zero shall be declared. Anysubsequent changes shall be termed Modifications and shall beconsidered for action under the Sea System Controllerate EquipmentModification Procedure. Proposals for such design changes shall besubmitted to the Prime Contractor;

(5) Alternative Manufacture: Where called for in the contract, copies of alldrawings, specifications, etc., necessary for an alternative contractor tomanufacture the Gearbox.

3.1.6.4 Quality Assurance of the Design

a. Conformance to Technical Requirements: During the preliminary approvalprocess any items covered by the SRD, which cannot be demonstrably met becauseof the preliminary nature of the information available, shall be listed. The itemslisted shall be subject to progressive design approval as the design proceeds.Drawings covering such items shall not be used for manufacture until designapproval has been obtained from the Prime Contractor.


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b. Quality of Drawings: Drawings submitted by the manufacturer shall be sampledat prescribed intervals to ensure that they conform to the requirements of Clause3.1.6.1b. The DPA will require the contractor to amend any errors found and tocertify that other drawings likely to contain similar errors have been examined andare correct.

3.2 Materials3.2.1 Wheels and Pinions

a. Materials, heat treatment processes and testing requirements, etc., for all gearingelements shall be in accordance with DEF STAN 02-381.

b. Wheel Shafts, Quill Shafts and Torque Tubes shall be of Forged Steel, and shallmeet the requirements of DEF STAN 02-848 Part 1 and/or Part 2 as applicable.

3.2.2 Gearcasesa. Main Propulsion Gearboxes shall be of fabricated Steel to the requirements of BS

EN 10028-1, BS EN 10028-2, BS EN 10028-3, BS EN 10028-4, BS EN 10028-5,BS EN 10028-6, BS EN 10028-7 and/or BS EN 10029, as applicable.

b. All welding shall meet the requirements of DG Ships/PS/9023.c. Proposed methods for the protection of Gearcases internal surfaces from the risk of

corrosion shall be submitted to the MOD. Phosphate Coating of any surfaces shallbe in accordance with DEF STAN 03-11.

d. Paint used on external surfaces of the Gearbox shall conform to BS 4800 colourcode 00A01 and DEF STAN 02-737.

3.2.3 Bearings

a. White metal to BS 3332 Type A shall be used for Journal and Thrust Bearings.

3.2.4 Lubrication Suction, Delivery and Drain Pipework

a. Guidance on LO is given in DEF STAN 02-303.3.2.5 Electrical Equipment

a. The materials of Electrotechnical equipment fitted to the Gearbox shall conform toDEF STAN 07-224.

3.2.6 Rubber O Rings

a. Elastomeric Toroidal Sealing Rings (O Rings) shall conform toDEF STAN 02-337 Part 1.

3.2.7 Shafts and Couplings

a. For oil operation Loose Couplings, hubs shall be made from Forged Steel having aYield Stress of not less than 750 N/mm2. The Shaft, unless forming part of the Gearelements, shall be made from Forged Steel having a minimum Ultimate TensileStrength (UTS) of 850 N/mm2.

b. For keyed Loose Couplings, unless forming part of the Gear elements, allcomponents shall be made from Forged Steel having the following minimumvalues of UTS:

(1) Hub and Shaft 850 N/mm2;

(2) Keys 550 N/mm2.

c. For involute Splined Couplings, both the Hub and the Shaft, unless forming part ofthe Gear elements, shall be made from Forged Steel having a minimum UTS of 850N/mm2.


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3.3 Gear Tooth Design

3.3.1 Helix Angle

a. Tooth pitches shall be minimized, consistent with Gear Tooth loadings and stresses.

b. The helix angle shall be as large as possible within the following constraints:

(1) For Single Reduction, Single Helical Gears, the desirability of keeping axialthrusts to a minimum shall be taken into account;

(2) For Double Reduction, Single Helical Gears, the first and second reductionhelix angles shall be arranged so that, taking account of end reliefs, thenumber of overlaps is as high as possible consistent with satisfactory thrustarrangements and, in the case of the second reduction, shall be at least two.

c. The unbalanced thrust in the intermediate shaft shall be a minimum, (consistentwith providing adequate location) taking into account the possible need to avoidheavy thrust on the high speed shaft.

3.3.2 Tooth Form

a. Wheel and Pinion Teeth shall be of involute profile. A normal pressure angle ofMain Propulsion Gears shall be 20. Other pressure angles may be adopted whenjustified to be of advantage.

b. The tip radius on the Gear cutting tool shall be not less than 0.08 of the normal pitch.

c. The ends of pinion and wheel teeth shall be rounded-off or chamfered and the edgesat the ends of the teeth shall be well radiused.

d. Justified proposals for Profile Modification (tip, root and end relief) shall beprovided for consideration by the MOD.

e. The Gear Tooth root fillets of ground Gears shall be undercut and the transitionfrom ground tooth flank to unground root fillet shall be free from significant stressraisers.

f. The Gear Teeth shall be finished ground.

g. If steps are formed in the root and fillet section, the concession application shallinclude evidence of the effect on the total bending stress and any other penalties.This shall be supported by projections of casts of tooth sections of at least 20magnifications. Grinding of the root and fillet section to remove steps shall not becarried out without Prime Contractor approval. This does not apply to steps formeddeliberately as part of the normal manufacturing process (e.g. Protuberancehobbing). No handwork shall be done without Prime Contractor approval. Allsuch concessions shall be forwarded for consideration by the MOD.

3.3.3 Tooth Load Distribution

a. If it is necessary to obtain even distribution of load by correction of the pinionhelices, the calculations shall be submitted for agreement by the MOD.

b. With Single Helical Gears, misalignment shall be taken into account whencalculating tooth load distribution. Consideration shall be given to correcting toothload distribution in the ahead load condition by incorporating an adjustablebearing.


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3.3.4 Tooth Loading Analysis

a. An analysis of the gear elements shall be provided to the MOD using BS 436-3 andthe Newcastle University Design Unit analysis program KHBTEN, DUGATESor an equivalent accurate analytical mesh model.

b. Gear elements shall be analyzed using BS 436-3, with the following additions:

(1) The face load factor for contact stress (KH) shall be calculated usingNewcastle University Design Unit analysis program KHBTEN or anequivalent accurate analytical mesh model. This value shall be used in placeof the KH given by BS 436-3;

(2) In practice, the same results could be achieved by adjusting safety factorsagainst surface failure calculated using original BS 436-3 methods (oranalysis programme) by the ratio of square roots of the KH values calculatedusing both original BS 436-3 and KHBTEN, i.e.:Actual safety factor against surface failure, SH:

SH SHBS436

*K

HBS436

KH

KHBTEN

(3) The face load factor for bending stress (KF shall be calculated in

accordance with BS 436-3 equation 108 using the KH value calculated fromthe analysis program KHBTEN or an equivalent analytical mesh model.This value shall be used in place KH given by simple application of BS436-3.

(4) In practice, the same result could be achieved by adjusting safety factorsagainst bending failure calculated using original BS 436-3 methods (oranalysis programme) by the ratio of KF calculated using the originalBS 436-3 programme to that KF calculated using KH from KHBTEN, i.e.:Actual safety factor against surface failure, SF:

SF SFBS436

*K

FBS436

KF

KHBTEN

NOTE Safety factors derived from this agreed stress analysis procedure shall only beused for comparing the gears of similar design and should not be used as anabsolute measure of safety margins.

c. For those BS 436-3 stress and load modification factors where there is a choice, thePrime Contractor shall demonstrate that achievement of the design safety factors isobtained for a credible range of values.

3.3.5 Gear Element Safety Factors

a. The Gearbox shall exceed the minimum safety factors as detailed in the table belowwhen rated in accordance with the above.

Minimum Safety Factor

Surface Stress (SH) Bending Stress (SF)

Primary Gears 1.3 1.6

Secondary Gears 1.3 1.6


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3.3.6 Scuffing

a. The ability of the Gearing to operate without scuffing at loads up to and includingthe maximum specified transient overload shall be demonstrated to the MOD usingat least two different methods. The assessment shall take full account of predictedtransverse load distribution. The results of the assessment, together with the inputdata and details on the methods used, shall be forwarded for consideration by theMOD.

3.4 Gear Construction

3.4.1 General

a. Where possible, rotating elements shall not to be handed.

b. The drive to the Primary Reduction Pinions shall be taken though FlexibleCouplings of an approved design. See Clause 3.9.

3.4.2 Gear Element Construction

a. Pinions shall be forged integrally with their Shafts. A built-up design with the GearTooth portion shrunk on or keyed to the shaft may be considered when the sizewarrants this.

b. Where possible, Gear Wheels shall have Forged Steel, Cast Steel, or high-duty Ironcentres. However, fabricated, i.e. bolted or welded construction, may be usedwhere appropriate.

3.4.3 Accuracy

a. The accuracy of all Main Propulsion Gears transmitting more than 750 kW shallcomply with BS 436-4 and/or BS 436-5, as applicable, subject to the additionalrequirements described in Clauses 3.4.3d to 3.4.3i. The accuracy shall be verifiedby use of the procedures described in the BGA Codes of Practice DUCOP.03.

b. The terminology and symbols used on drawings and in all associateddocumentation shall be in accordance with BS ISO 701 and BS ISO 1122.

c. Notice shall be taken of the recommendations regarding drawing information andGear specification in BGA Codes of Practice DUCOP.01 and DUCOP.02.

d. The tolerances on runout of functional mounting surfaces given in BGA Codes ofPractice DUCOP.02 shall apply to the peripheries of all Coupling Flanges. Theyshall also apply to the Thrust Faces, the outside diameter of the Thrust Collar beingused in the formula.

e. Undulations are cyclic variations in the shape of the flanks of the teeth which areorientated such as to produce sinusoidal (pure tone) variations in transmissionerror. This variation leads to the generation during running of phantom tones whichnot only increase the general noise level but also give a distinctive and oftenunacceptable pattern to the noise quality.

f. Because of the difficulties in measuring undulations to sufficient accuracy andbecause insufficient work has been done to quantify the effect, specific tolerancescannot be given. Therefore, the aim should be to minimize the effect.

g. As a guide, the magnitude of the relevant component of the transmission error shallbe no more than 1 m and preferably less than 0.5 m.

h. The surface texture of the Tooth flank shall be no worse than 0.6 m Ra and in theroots no worse than 2.0 m Ra.


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i. If Double Helical Gears are used, the differences between the cumulative pitcherrors on the helices over corresponding arc lengths Lm shall not exceed:

0.35 Lm 9.5

NOTE Lm is defined as to the number of base pitches.

j. The surface roughness of journals measured in the axial direction shall not exceed2.0 m Ra.

3.4.4 Identification

a. Each Gear element shall be uniquely and indelibly marked to show the following:

(1) The Manufacturers Drawing Number with issue status to which the Gearwas made;

(2) A unique identification number which can relate each Gear to its inspectionrecords;

(3) A reference tooth and the identification of the ahead or loaded flank. Thismark shall be positioned to be visible when the Gear is installed in theGearbox and viewed through a convenient inspection plate.

3.5 Gear Case Design

3.5.1 General

a. Importance is attached to the rigidity of the Gear supporting structure and that themeshing and alignment are maintained under load. Main Gearcases shall bedesigned to be supported on a limited area at three places to minimize thetransmission of distortion from the ships structure and to provide a datumcondition during manufacture and installation. The Gearcase should preferably bedesigned so that all the high speed (input) line bearing housings are integral and notcantilevered from the Main Gearcase. If a cantilevered bearing housing isunavoidable it shall be subjected to a thorough assessment of vibration modes at thedesign stage.

b. Reference surfaces shall be provided on the Gearcase structure to facilitatealignment/level checking equipment. These surfaces shall be positioned to enableany Gearcase distortion to be measured with the minimum of effort, i.e. no coversshall be removed.

c. The Gearcase shall be suitably subdivided to provide access to the Gears, Bearings,Couplings, Clutches and Thrust Blocks. Where Clutches are fitted, guards shall beprovided to prevent any debris ejected from the clutches from entering the Gearmeshes (see also Clause 3.10).

d. The design of the Gearcase shall ensure that it may be fully drained when required,i.e. without leaving pockets of oil trapped inside the Gearcase.

e. Gearcases shall be designed to provide the maximum access to the Gearboxinternals with the minimum dismantling of internal and external pipework andcabling. To this end consideration shall be given to the design of the Gearcasecovers and the routeing of pipework and cables. In particular the number ofpenetrations through the Gearcase shall be minimized and such penetrations shallbe located in covers or frames least likely to be disturbed.


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f. The Gearcase covers shall be of lightweight fabricated steel construction. Thecovers shall be subdivided for ease of handling. Separate covers shall be fitted toFlexible Couplings, so that the Couplings can be inspected, removed and replaced,without opening the Main Gearcase.

g. The arrangement of Primary Reduction Pinion input flanges shall permit alignmentbetween Prime Movers and Gears to be checked without lifting Gearcase maincovers. If necessary, temporary covers shall be provided for the Primary Pinioninput flanges to close the Gearbox against ingress of air during transport anderection.

h. Sufficient bearing housings shall be adjustable or fitted with intermediate liners sothat the alignment of all gear meshes can be corrected if required without recourseto handwork (e.g. scraping or filing).

i. If the Main Thrust Block is integral with the Gearcase, adequate space shall beprovided for access and dismantling. The surrounding structure shall be adequatelystiffened to prevent excessive distortion of the Gearcase by the thrust forces.

j. Sufficient inspection doors shall be provided to permit visual inspection of all Gearmeshes and LO sprays. Inspection plates shall be provided with starting screws andsecurity shall be achieved by the use of padlocks, the object being to prevent ordetect unauthorized access to the Gearbox. A diagrammatic sketch shall beproduced showing location of all locking devices.

k. The design of the Gearcase and covers shall be such that no leakage shall occurwhen the Gearbox is filled completely with oil with the shaft penetrations coveredby suitable blanks.

l. The whole of the electrical installation, inside and outside the Gearcase, shall be inaccordance with DEF STAN 02-502. Consideration shall be given to equipmentinside the Gearcase with regard to the oil-laden atmosphere, especially where oilsprays play directly on to electrotechnical equipment or cable fastenings. Allelectrical items shall be earthed to meet the limits stated in DEF STAN 02-502.

m. Cabling in rigid or flexible conduit or trunking shall be supported to preventchafing under vibration. Bushing shall be provided where there is a need to protectthe cabling. The minimum bending radii for cables shall be observed. The whole ofthe cabling shall be capable of being removed and replaced without disturbance ofthe Gearbox fittings, pipework, etc. Conversely, Gearbox fittings, pipework, etc.,shall be capable of removal without disturbance of cabling and conduit.Interference precautions shall be observed.

n. Junction Boxes and all cable terminals shall be in accordance withDEF STAN 02-514 (watertight to the degree required by Clause 1.1.2a.(13)) andshall be tested by immersion prior to installation. Gearboxes which have a Shipcabling interface shall be sited to enable direct installation of cabling by theShipbuilder. All fasteners on the Gearcase required for Shipbuilders cables shallbe provided by the Gearbox manufacturer.

o. Internal surfaces of Gearboxes shall be treated to prevent corrosion. The externalsurfaces of Gearboxes shall be painted (see Clause 3.2.2d.).

p. An Equipment Identification and Modification Plate shall be fixed to the Gearcasein a visible position. Additional plates shall be provided for each majorsub-assembly for which separate modification action is intended. The plates shall


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conform to DEF STAN 02-723 and shall also identify the screw thread series usedthroughout the design. A drawing of the plates shall be submitted for PrimeContractor approval.

q. Provision shall be made for earthing the Gearcase to the Ships structure inaccordance with DEF STAN 02-502.

r. Shaft oil seals shall be designed to fail safe, i.e. do not result in metal-to-metalcontact between moving parts.

3.6 Lubrication and Venting

3.6.1 General

a. The LO distribution and return arrangements within the Gearbox shall conform tothe requirements of DEF STAN 02-303.

b. The type of LO to be used in the Gearbox shall be specified in the SRD.

c. The LO supply to each Main Gearcase shall be by one connection from the Shipssystem to an external straight manifold secured to the Gearcase. For single gearboxinstallations, connections shall be provided to supply the common manifold fromeach side of a sided system. Non-return Valves shall be supplied at each end of themanifold to preserve integrity of the LO supply during a fault condition to one side.

d. LO supplies to Bearings, Sprayers, Thrust Block, etc., shall be taken from the top ofthis manifold.

e. LO supplies to Journal Bearings shall be grouped on a speed basis so that thesupplies to the various groups can be individually controlled. Sprayer suppliesshall be similarly controlled and grouped.

f. Plain Thrust Bearings may be lubricated by the LO flows from adjacent JournalBearings but Thrust Bearings of the pivoted pad type shall be provided withseparate oil supplies.

g. The control of each group shall be by suitable lockable control valves with aminimum opening. The maximum number of individual supplies in any one groupshall not to exceed four.

h. Internal oil passages for oil to the Bearings and Sprayers shall consist of lengths ofpiping or drilled holes through thick plate sections accessible for cleaning at eachend. Cast passages shall not be used. Pipe couplings of the olive or cone type musthave their nuts secured by a method approved by the Prime Contractor.

i. A flushing outlet shall be provided on each Bearing Housing in order that the oilsupply arrangements up to and including those in the housing may be flushedwithout the contaminated oil having to pass through the bearing clearance.

j. The requirement for a separate or integral Drain Tank shall be specified in the SRD.The design of integral drain tanks shall conform to DEF STAN 02303. If aseparate Drain Tank is specified, the Gear sump and drain pipework shall be ofsufficient size to ensure that none of the rotating elements come into contact withthe oil which collects in the base of the sump under normal operating conditions.


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k. The Gearbox shall be designed to minimize the ingress of air under all operatingconditions. System ventilation shall be provided from the drain tank in accordancewith DEF STAN 02303. No vents shall be fitted to the Gearcase other than aconnection to the Drain Tank if this is separate or to the Drain Tank Vent (see Clause3.6.1l.).

l. All Marine Gearboxes for military applications experience significantly longerperiods of shut-down when compared with commercial applications. This resultsin corrosion damage of the Gearcase internal elements. Therefore all Gearboxesfor military applications shall be fitted with a Dehumidifier to remove moist airfrom the Gearcase during periods of shut-down.

m. The dry air produced by the Dehumidifier shall have a relative humidity of no morethan 30 per cent at 15C. The dry air supply pipes shall lead from the Dehumidifierinto the upper area of the Gearbox so that the Gearbox is fully ventilated. The moistair shall be vented from the lower area of the Gearbox via pipe(s) leading to theDrain Tank or Drain Tank Vent pipe. These pipes shall be designed;

(1) to prevent condensate running back into the Gearbox;

(2) so that they do not become submerged by oil during Gearbox flushing.

n. All pipes going into or out of the Dehumidifier shall be fitted with lockable valvesthat can be locked shut when the Dehumidifier is not in use. Dehumidifier airintakes shall take air from the compartment and shall be fitted with mesh guards toprevent ingress of dirt. Instrumentation shall be fitted that will activate an alarm ifthe dry air from the Dehumidifier goes above 30 per cent RH at 15C. The electricsof the Dehumidifier and instrumentation shall be in accordance with DEF STAN02-625 and DEF STAN 59-36.

3.6.2 Lubrication

a. The SRD shall include a requirement that where any oils or greases are used orrequired for any purpose they shall wherever possible be specified from those listedin DEF STAN 01-5. If this is not possible it shall be brought to the attention of thePrinciple Contracts Officer and/or the Design Authority, as applicable forresolution.

3.7 Bearings

3.7.1 General

a. The preferred Bearing type for Gearboxes are White Metal lined, thin to mediumwalled Plain Bearings. Rolling element Bearings or Thrust Cones may be usedwhen demonstrated to be of advantage.

b. Bearing Shells shall be pre-finished, Steel backed, lined with White Metal made byan approved manufacturer. The Shells shall be of the thin to medium walled style(wall thickness less than 4 per cent of the bearing bore), but subject to a minimumwall thickness of 5 mm. Exceptionally, Main Wheel Bearings may be of thick wallconstruction other than of Steel if preferred by the Gear manufacturer.


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3.7.2 Steel Backings

a. Steel Bearing backings shall be manufactured from a low Carbon Steel (less than0.2 per cent Carbon).

b. Steel Bearing backings shall be produced by forging, bending or pressing platematerial. Forged Steel backing halves shall be normalized and stress relieved.Bearing backings bent or pressed from plate material a shall be stress relieved.Alternatively, for bearings up to 250 mm bore, Steel strip may be lined with whitemetal prior to forming and no stress relieving shall be required.

3.7.3 White Metal Lining

a. Chemical composition of White Metal shall conform to BS 3332 Type A.

b. The White Metal lining thickness depends on the bore diameter of the BearingShell. The following table shows the general rule for applying White Metalthickness:

Bearing bore diameter in mm White Metal thickness in mm

up to 250 1.0

251 to 500 1.5

501 and over 2.0

c. The variation of the White Metal thickness, in the operational area of eachindividual Bearing Shell shall not exceed 0.2 mm. However, 0.25 mmthickness variation is permitted within 20 of the Bearing butts to allow fordeformation during machining operations.

d. Casting of the White Metal lining onto preformed Shells shall be be carried outcentrifugally. The rotational speed shall be adjusted for each particular diameter tominimize segregation of the White Metal constituents.

e. Surface finish of the White Metal after final machining shall be in accordance withthe following the table:

Bearing bore diameter Surface finish to be better than

up to 400 mm 0.8 m Ra401 mm and over 1.6 m Ra

f. The White Metal of a pre-finished bearing shall not be scraped or finished by hand.

3.7.4 Bearing Design and Analysis

a. The maximum specific load (maximum Bearing load divided by projected area) forJournal Bearings shall be less than 34.5 bar for all Bearings, except Main WheelBearings, which shall have a maximum specific load of less than 24.5 bar. Loadingpressures other than those above shall be justified to the MOD.

b. For Thrust Bearings or Thrust Cones, the assumptions made in estimating the axialload shall be explicitly stated. Thrust Bearings or Thrust Cones associated with finetoothed Gear Couplings or Synchronous Self Shifting (SSS) Clutches shall be sizedto accept the maximum axial force which the sliding teeth could transmit at fullload, assuming a coefficient of friction of = 0.3.

c. Thrust Cones shall be designed using the Thrust Cone Design Aid packageavailable from the MOD.


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d. The Prime Contractor shall shall submit a Bearing design justification, presentingthe results of the Bearing analysis carried out for all the Gearbox Bearings (Journaland Thrust Bearings). The extremes of operating conditions within the specifiedduties shall be used. A minimum requirement, for the following list of Bearingoperating characteristics, shall be provided for each particular load caseconsidered:

(1) LO flow rates and temperatures;

(2) Positions (Journal Bearings only) and thickness of minimum LO films;

(3) Maximum Bearing surface temperature;

(4) Approximate threshold speeds of Journal Bearing instability (half-speedwhirl).

e. The mean temperature of the LO return from any individual Bearing shall notexceed 85C.

f. The maximum temperature recorded in service by the normal Bearing TemperatureMonitoring Equipment (see Clause 3.7.8a.) shall not exceed 115C under anyspecified operating condition. If this limit is exceeded during Shop Tests, ShoreTrials or Contractors Sea Trials (CST), the Prime Contractor shall be required to fitmodified Shells to the affected unit(s) and to replace or modify any spare Shellswhich have been purchased by the MOD or their agents, free of charge to the MOD.

3.7.5 Oil Inlets

a. For plain Journal Bearings, twin axial LO inlets positioned at the bearing butts shallbe used. When assembled in the Gearbox the butts shall be positioned at least 20away from the closest point of approach of the position of the calculated minimumLO film thickness under any operating condition. If this cannot be achieved acircumferential groove may be used. As there is a risk of cutting off the LOcompletely under shock or other abnormal load conditions single axial LO inletsare not preferred; they shall only be used where there is no practical alternative.

3.7.6 Housing

a. The Bearing and housing designs shall ensure that the Bearing is located uniquelyin its correct position, thus ensuring that incorrect assembly, resulting in restrictedLO supply or drainage, cannot occur.

b. Where offset pivoted pads are used for Thrust Bearings, provision shall be made inthe Bearing housing design to locate the pad uniquely to eliminate the possibility ofincorrect assembly.

c. During design, attention shall be drawn to the requirement to check that JournalBearing housings have sufficient stiffness and that their clamping systems havesufficient strength to enable the necessary clamping force (nip) to be applied to theBearing Shells.

3.7.7 Fitting

a. Each Bearing shall be so arranged that it can be turned out with the Journal in place;the necessary appliances being provided. Fittings independent of the hull structure,shall be provided to take the weight of the Main Gearwheel to facilitate thisoperation and similar fittings shall be provided for other Bearings if required.


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3.7.8 Caps

a. Separate Steel Bearing Caps shall be fitted for each Bearing. Provision shall bemade to prevent the Bearing rotating. The Bearing Caps shall be independent of theGearcase covers. Where liners are used, Bearing Caps shall be positively locatedrelative to the lower housing.NOTE Where the Bearing Shells are carried within a liner separate from the

Gearcase housing, the above requirements for nip location, etc., shallapply to the liner.

3.7.9 Vibration Measurement

a. Each Bearing Cap shall be drilled, tapped and seatings prepared to accept twotransducers to measure radial vibration, one in the vertical direction and one in thehorizontal direction. This shall be provided even if vibration instrumentation is notspecified for each Bearing Cap; this will allow instrumentation to be fitted for trialsif required.

3.7.10 Temperature Measurement

a. Arrangements for measuring Bearing temperatures shall be provided in accordancewith Clause 3.12. Two electrically powered thermosensing elements shall befitted to each Main Transmission Journal Bearing (one active, one spare).Additional sensors may be required on Bearings operating under a multiplicity ofattitudes.

3.8 Turning Gear

3.8.1 General

a. The Gearbox shall be provided with a means of turning the Prime Movers, Gearingand Propeller Shafting for inspection and maintenance purposes. The MainTurning Gear shall be designed to turn the Main Shaft continuously in the range of 5rpm to 10 rpm. Arrangements shall be provided to enable the Turning Gear to beoperated by hand.

b. The Turning Gear shall be capable of being engaged, disengaged, started andstopped by both local and remote operation.

c. Turning Gear engagement and disengagement indication shall be provided bothlocally and remotely.

d. The Turning Gear shall be capable of being stopped locally at all required angles ofrotation for inspection purposes and to lock the Shafting System.

e. Interlocks shall be provided as necessary to prevent inadvertent operation orpotentially dangerous states arising within the Gearbox and shall be simple,fail-safe and of high integrity. The following interlocks shall be provided:(1) To ensure that the Turning Gear cannot be engaged and operated at any stage

during normal running configurations;(2) A signal on the Turning Gear Clutch to inhibit starting of the Main Engines

when the Clutch is engaged;(3) An interlock on the Turning Gear motor/starter to prevent operation of the

motor if the Shaft Brake is pressurized, or the Hand Turning Gear engaged;(4) A signal on the Turning Gear motor to inhibit operation of the Shaft Brake

when the motor is running.


32

f. The arrangement of the Turning Gear and Engine Clutches shall be such that theTurning Gear is capable of rotating all transmission components, including thePrime Movers in both directions. An inching control shall be provided at least inthe ahead direction. The Turning Gear motor control shall be fitted with anextension lead of sufficient length to permit operation of the Turning Gear from aposition by any of the Gearbox inspection doors.

g. A Clutch, driving positively in both directions, shall be incorporated in the TurningGear drive. Arrangements shall be made whereby the Clutch can be positivelysecured in the engaged and in the disengaged positions.

h. A locking device shall be fitted in association with the Turning Gear, capable ofholding the Gearing and Shafting stationary against at least 50 per cent of the designFull Power ahead torque.

i. Electric Turning motors and equipment shall not be required to be watertight.However, the design of the Turning Gear for HM Surface Ship Gearboxes shallensure that no water can enter the Main Gearcase when submerged in sea water.(See Clause 1.1.2a.(13)). Motors shall generally be in accordance with DEFSTAN 02-627 and DEF STAN 07-244. Starting and control shall be in accordancewith DEF STAN 02-636.

3.9 Shafts and Couplings

3.9.1 General

a. The responsibility for the design of the input line Flexible Couplings, including thedetail design of the flange connections to the prime mover(s), shall ensure that theTorque Tube and associated flanges are such that an adequate standar