NES 304 Part 2 Shafting Systems and Propulsors

Shafting Systems and Propulsors

Part 2Design Requirements for Main Propulsion

Shafting Auxiliaries

Ministry of Defence Defence Standard 02-304 Part 2

Issue 2 Publication Date 19 August 2002

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 02-304 Part 2 Issue 1 1 April 2000NES 304 Part 2, Issue 2 October 1989NES 304 Part 2, Issue 1GMES 65 (PART)GMES 5 (PART)GMES 2 (PART)GMES 1 (PART)

1DEFENCE STANDARD 02304

SHAFTING SYSTEMS AND PROPULSORS

PART 2 ISSUE 2

DESIGN REQUIREMENTS FORMAIN PROPULSION SHAFTING AUXILIARIES

This Defence Standard is

authorized for use in MOD contracts

by the Defence Procurement Agency and

the Defence Logistics Organisation

Published by:

Defence Procurement Agency,An Executive Agency of The Ministry of Defence,UK Defence Standardization,Kentigern House,65 Brown Street,Glasgow, G2 8EX.

DEF STAN 02304 Part 2/ Issue 2(NES 304 Part 2)

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SCOPE1. Defence Standard (Def Stan) 304 Part 2 specifies the design requirements for shafting

auxiliaries fitted in HM Surface Ships and Submarines. It also defines the environmentalconditions under which shafting auxiliaries must operate and remain fully functional.


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FOREWORD

Sponsorship

1. This Defence Standard (Def Stan) is sponsored by the Defence Logistics Organisation (DLO),Ministry of Defence (MOD).

2. It is to be applied as required by any DLO contract for Main Propulsion ShaftingAuxiliariesbearings, brakes, glands, seals, etc.

3. The complete Def Stan 02304:

Shafting Systems and Propulsors comprises:

Part 1: Design Requirements for Main Propulsion Shafting;

Part 2: Design Requirements for Main Propulsion Shafting Auxiliaries;

Part 3: Manufacturing and Detail Design Requirements for Propulsors;

Part 4: Requirements for Repair of Main Propulson Shafting;

Part 5: Requirements for the Handling, Maintenance and Repair of Propellers for HMSurface Ships.

4. 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 existing departmental procedures.

5. If it is found to be unsuitable for any particular requirement, MOD is to be informed in writingof the circumstances.

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

7. Unless otherwise stated, reference in this Def Stan to approval, approved, authorized and similarterms means by the MOD in writing.

8. 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.

9. This standard has been reissued because of technical update.

Conditions of Release

General

10. This standard has been devised solely for the use of the MOD, and its contractors in the executionof contracts for the MOD. To the extent permitted by law, the MOD hereby excludes all liabilitywhatsoever and howsoever arising (including but without limitation, liability resulting fromnegligence) for any loss or damage however caused when the standard is used for any otherpurpose.

11. 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.

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


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MOD Tender or Contract Process13. This Defence Standard is the property of the Crown. Unless otherwise authorized in writing by

the MOD it must be returned on completion of the contract, or submission of the tender, inconnection with which it is issued.

14. 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.

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

16. The Category of this Def Stan 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 Documents17. In the tender and procurement processes the related documents listed in each section and Annex

A can be obtained as follows:a. British Standards British Standards Institution,

389 Chiswick High Road,London, W4 4AL.

b. Defence Standards, Defence Procurement Agency,An Executive Agency of The Ministry of Defence,UK Defence Standardization,Kentigern House,65 Brown Street,Glasgow, G2 8EX.

c. Other documents Tender or Contract Sponsor to advise.18. All applications to Ministry Establishments for related documents are to quote the relevant MOD

Invitation to Tender or Contract number and date, together with the sponsoring Directorate andthe Tender or Contract Sponsor.

19. Prime Contractors are responsible for supplying their subcontractors with relevantdocumentation, including specifications, standards and drawings.


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Health and SafetyWarning

20. This standard may call for the use of processes, substances and/or procedures that may be injuriousto health if adequate precautions are not taken. It refers only to technical suitability and in no wayabsolves either the supplier or the user from statutory obligations relating to health and safety atany stage of manufacture or use. Where attention is drawn to hazards, those quoted may notnecessarily be exhaustive.

21. This standard has been written, and is to be used, taking into account the policy stipulated inJSP 430 MOD Ship Safety Management System Handbook.Additional Information(There is no relevant information included)


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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 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Additional Information 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CONTENTS 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SECTION 1. PERFORMANCE SPECIFICATION 8. . . . . . . . . . . . . . . . . . . SECTION 2. NATIONAL/INTERNATIONAL REGULATIONS 8. . . . . . . . SECTION 3. MILITARY STANDARDS/REQUIREMENTS 8. . . . . . . . . . . .

3.1 Environmental Conditions 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 Drawings 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Materials 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 Manufacture, Installation and Trials 8. . . . . . . . . . . . . . . . . . . 3.4.1 General 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.2 Welding 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.3 Seating 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.4 Limits and Fits 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.5 Finish 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.6 Marking 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.7 Testing 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.8 Installation 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.9 Trials 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 4. DESIGN REQUIREMENTS/GUIDANCE 10. . . . . . . . . . . . . . 4.1 Main Shaft Bearings 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.1 General 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.2 Stern Tube and Bracket Bearing Barrels 10. . . . . . . . . . . . . . . . 4.1.3 Stern Tube and Bracket Bearing Bushes 10. . . . . . . . . . . . . . . . 4.1.4 Stern Tube and Bracket Bearings -

Preferred Types and Materials 11. . . . . . . . . . . . . . . . . . . . . . . . 4.1.5 Alternative Bearing Materials 12. . . . . . . . . . . . . . . . . . . . . . . . . 4.1.6 Bearing Length/Diameter Ratio 12. . . . . . . . . . . . . . . . . . . . . . . Table 4.1 Length to Diameter Ratio 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.7 Bearing Pressures 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Table 4.2 Bearing Pressures 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.8 Bearing Clearance 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.9 Lubrication 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.10 Plummer Bearings General 13. . . . . . . . . . . . . . . . . . . . . . . . .


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Page No4.1.11 Seatings 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.12 Plummer Bearing Types 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.13 Design Requirements 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 Design Requirements Bulkhead Glands 15. . . . . . . . . . . . . . . 4.2.1 General 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.2 HM Surface Ships 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.3 Submarines 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 Stern Seals 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.1 General 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3.2 General Design Requirements 16. . . . . . . . . . . . . . . . . . . . . . . . . 4.3.3 Design Requirements for HM Surface Ship Stern Seals 17. . . . 4.3.4 Design Requirements for Submarine Stern Seals 17. . . . . . . . . 4.3.5 Design Requirements for Soft Packed Glands 17. . . . . . . . . . . . 4.4 Shaft Brake and Locking Gear 18. . . . . . . . . . . . . . . . . . . . . . . . 4.4.1 Shaft Brake General 18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.2 Design Requirements 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4.3 Shaft Locking Gear - General 19. . . . . . . . . . . . . . . . . . . . . . . . . 4.4.4 Design Requirements 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 Thrust Block Bearings 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.1 General 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.2 Seatings 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.3 Design Requirements 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.4 Thrustmeter/Resonance Changer 21. . . . . . . . . . . . . . . . . . . . . 4.5.5 Trailing Thrust Bearing 21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6 Thrustmeters 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7 Resonance Changers 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7.1 General 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7.2 Design Procedure 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8 Shaft Earthing and Cathodic Protection Devices 23. . . . . . . . 4.8.1 General 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.8.2 Interface Requirements 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9 Shaft Interface for Shaft Driven Auxiliaries 24. . . . . . . . . . . . 4.9.1 General 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9.2 Design Requirements 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SECTION 5. CORPORATE KNOWLEDGE AND EXPERIENCE 24. . . . . 5.1 Special Service Air Transfer Box 24. . . . . . . . . . . . . . . . . . . . . . 5.1.1 General 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.2 Design Requirements 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.3 Design Information 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ANNEX A. RELATED DOCUMENTS 27. . . . . . . . . . . . . . . . . . . . . . . . . . .

ANNEX B. ABBREVIATIONS AND DEFINITIONS 29. . . . . . . . . . . . . . .

ANNEX C. PROCUREMENT CHECK LIST 30. . . . . . . . . . . . . . . . . . . . . .

ALPHABETICAL INDEX 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


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1. PERFORMANCE SPECIFICATIONThis Defence Standard contains no Performance Specification information.

2. NATIONAL/INTERNATIONAL REGULATIONSThis Defence Standard contains no national/International Regulations information.

3. MILITARY STANDARDS/REQUIREMENTSRelated Documents: BS EN 20286 Parts 1 and 2; BS EN 1563; BS 1134; BS 1916;Def Stan 02352; Def Stan 02362; Def Stan 02722; Def Stan 02723; Def Stan02745; Def Stan 02772; Def Stan 02863; Def Stan 08123; EN-GJS-350-22; see alsoAnnex A.

3.1 Environmental Conditions

a . For HM Surface Ships the conditions in which the equipment must operate aredefined in Def Stan 08123.

3.2 Drawings

a . Drawings are to be prepared in accordance with Def Stan 02722.b . In addition to the Datum Pack drawings the Contractor is to supply one

as made process master of equipment drawings specified by DefenceProcurement Agency (DPA).

3.3 Materials

a . Where specific materials are required they are specified in the relevant equipmentsection. Where materials are not specified, then the material chosen by the designeris to meet all requirements of this standard.

b . When a material is specified it is not intended to preclude the use of an alternative,or the introduction of a new material which is equally or more suitable, but anychange requires DPA approval.

c . Ferrous and non-ferrous castings of components are to conform to the requirementsof Def Stan 02745 and Def Stan 02863. Cast iron is not to be used for anyequipment or fittings, except that nodular cast iron to BS EN 1563 andEN-GJS-350-22 may be used where approved by MOD(N).

d . Materials which constitute a fire hazard or can emit toxic fumes are not to be used inmachinery spaces.

e . The Contractor is normally to supply all materials and components needed for themanufacture including NATO codified items. Any component ancillaryassemblies, which it is proposed to supply for embodiment in the equipment, willbe stated in the contract documents.

3.4 Manufacture, Installation and Trials

3.4.1 General

a . All materials are to be in accordance with the relevant approved MaterialSpecifications. The standard of inspection throughout the construction of the


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equipment and its component parts shall ensure that the specified material,accuracy, finish and cleanliness are achieved. Any process which is the subject of aprocess specification is to conform to it.

3.4.2 Welding

a . Welding is to conform to Def Stan 02772.

3.4.3 Seating

a . Support surfaces of seatings are to be machined to suit the feet of the equipmentafter the seating has been permanently installed in the ship.

3.4.4 Limits and Fits

a . All machinery is to be manufactured to the tolerances specified on the drawing.Tolerances are to conform to BS 1916 using the hole basis with unilateraltolerancing and using the preferred fits given in BS EN 20286 Parts 1 and 2.

3.4.5 Finish

a . All exposed fittings and surfaces must resist the accumulation of dirt and water andare to be polished or treated to require the minimum of attention.

b . All bright machine parts are to be of corrosion resistant material or suitably rustproofed.

c . Surface finish is to be specified in accordance with BS 1134.

d . Where the surface finish of mating parts is important, as with rotary oil seals, therequired finish must be given on the drawings of both mating components. (See BS1134).

3.4.6 Marking

a . Each equipment and, where stipulated, its associated assemblies andsub-assemblies, are to be fitted with identification and modification platesconforming to Def Stan 02723.

3.4.7 Testing

a . Testing of equipment covered by this Defence Standard is to be in accordance withDef Stan 02362.

3.4.8 Installation

a . The shipbuilder is responsible for the satisfactory installation and alignment of allequipment covered by this standard.

3.4.9 Trials

a . Shipboard and sea trials are to be conducted in accordance with Def Stan 02352.


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4. DESIGN REQUIREMENTS/GUIDANCERelated Documents: BS EN 20286 Part 2; BS 1134; Def Stan 02304 Part 1; Def Stan02704; Def Stan 02747; Def Stan 02791; Def Stan 02839; Def Stan 02849; see alsoAnnex A.

4.1 Main Shaft Bearings

4.1.1 General

a . The function of propeller shaft bearings is to support and align the main shaft. Thefollowing bearing arrangements may be used:

(1) Bracket bearings outboard, plummer bearings inboard;(2) As (1) with a stern tube bearing in way of the hull penetration;(3) As (2) with the stern tube extended to include the bracket bearing or bearings.

b . Each bearing is to be capable of refit by replacement with the shaft and propulsorin-situ.

4.1.2 Stern Tube and Bracket Bearing Barrels

a . The design of bracket bearing barrels is the responsibility of the ship designer andmust meet the following requirements:

(1) The position of bracket barrels is to be in accordance with the shaft alignmentrequirements designed in Def Stan 02304 Part 1;(2) The size of the barrels, the position of their support arms, rope guards orfairing pieces fitted on the bracket ends, are to give an acceptable water flow intothe propeller and through the bracket bearings;(3) The barrel bore diameter is to be compatible with the outer diameters of thebearing bush and the shaft withdrawal arrangements;

(4) Barrels are to be slope bored unless the product of bearing length and shaftslope is small compared to the bearing radial clearance;(5) Barrel bores are to be machined to BS EN 20286 Part 2 grade H9 with asurface finish to BS 1134 grade N6;(6) The barrel is to be fitted with a poker-type weardown gauge which can beused when the ship is afloat if necessary by a diver;(7) Arrangements are to be made for filling the spaces between the lands of thebearing bushes and the stern tube or bracket barrel, with a preservative to excludewater and prevent corrosion.

b . Stern tube barrels are built into the ship structure and are to be supportedlongitudinally along the length containing the bearing bush or bushes. The designof stern tube barrels is the responsibility of the ship designer.

4.1.3 Stern Tube and Bracket Bearing Bushes

a . For outboard bracket bearings the bearing bush is to extend the full length of thebearing barrel, while for stern tube bearings, the bush need only be long enough toprovide the required bearing surface.


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b . The bush is to:

(1) Be made from Nickel Aluminium Bronze (Ni Al Br) to Def Stan 02747 -AB2;

(2) Be made in halves with the longitudinal joint inclined 1 in 200 to the axis ofthe shaft to facilitate withdrawal. The joint should be inclined downwards towardsthe direction of withdrawal (flanged end of bush);(3) Be provided with fixings for temporary bolts to hold the bearing halvestogether during machining;

(4) Be flanged at one end. This flange is to embody bearing location andsecuring holes and suitable screwed holes to assist bearing withdrawal. It is also tobe stamp-marked TOP and BOTTOM on the respective halves and on the tophalf with the legend TOP HALF TO BE WITHDRAWN FIRST;

(5) Be bored concentric with the outside diameter;(6) Have the outer diameter machined in a series of constant steps which are to besize gauged from the mating barrel bore to give a sliding fit. The length of thesesteps is to have an aggregate contact with the barrel of at least one third of the barrelbore surface area;

(7) Be provided with suitable lifting holes. The holes should be spot faced toaccept collar eye-bolts and stamped locally with the thread diameter and pitch;

(8) Be drilled for a poker-type weardown gauge. In the case of the forward sterntube bearings, if access to a poker gauge in the bearing bush is not feasible, thedrilling should be located as near to the bearing as possible, e.g. in the stern sealhousing;

(9) Be provided with longitudinal dovetailed grooves for the circumferentiallocation of the bearing staves or pads unless dovetailed keeper plates are used. Aswould be the case with the modified bearing segment profile where the woods arein two halves for extended bearing life and improved slow speed runningcharacteristics;

(10) Be provided with split locking rings, one at each end, for the axial location ofthe bearing staves or pads.

4.1.4 Stern Tube and Bracket Bearings - Preferred Types and Materials

a . The preferred types of stern tube and bracket bearing are:

(1) Multiple rubber stave type;(2) Reinforced phenolic resin segmented pad type.

NOTE 1. Reinforced Phenolic Resin (RPR) materials containing asbestos are not to be usedwithout the express authorization of DPA.

2. Where significant use in shallow waters/sandy conditions is expected, RPR pads areto be used. Use of rubber, however in these conditions will cause high journal wear.


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b . The number and spacing of rubber bearing staves are to be based on manufacturersstandard widths and on the lubrication requirements. The total length is to be madeup from standard lengths or cut from standard strips after allowance has been madefor expansion of the rubber under load. The segments should be inserted so that thebutts in adjacent rows are offset. The manufacturer is to provide a specification ofhis product sufficiently detailed to fully define materials and properties whichaffect bearing performance.

c . The number, subtended angles and spacing of RPR bearing pads are to be based onthe lubrication requirements and on the requirements of length to diameter ratio andbearing pressure specified in Clauses 4.1.6a and 4.1.7a . The total length of thebearing material may be built up from standard lengths as supplied by themanufacturer. The end length is to be cut, as necessary, after allowance has beenmade for expansion of the pad material when immersed in water.

4.1.5 Alternative Bearing Materials

a . Oil lubricated white metal stern tube bearings may be used if the lead shipbuilderhas evidence of improved suitability for the specified duty. Oil lubricated whitemetal stern tube bearings are to conform with all the requirements of Clause 4.1.3b except that:

(1) The bush material is to be cast steel to Def Stan 02849 and the white metal inthe bush bore is to be to Def Stan 02839;

(2) Seals are to be provided fore and aft of the bearing to prevent ingress of waterand loss of lubricant. Consideration should be given to provision of back-upseals to ensure that oil is not lost to sea in order to comply with current pollutionregulations.

4.1.6 Bearing Length/Diameter Ratio

a . The bearing length to diameter (L/D) ratio is to be kept to a minimum and shouldnot exceed those in Table 4.1.

b . Before exceeding the ratios in Table 4.1 to keep bearing pressures within theirprescribed limits, consideration is to be given to increasing the shaft diameterwithin the bearing. The effect of this increase must however, be acceptable to theoverall shaft design.

Bearing LocationMaximum L/D Ratio

Bearing LocationRPR White Metal Rubber

Main A Bracket 2 - 4

Inter A and P Bracket 1.5 - 3

Stern Tube with no A/P Bracket 2 2 4

Stern Tube with A/P Bracket 1.5 2 3

Table 4.1 Length to Diameter Ratio

4.1.7 Bearing Pressures

a . Bearing pressures are to be calculated by dividing the shaft load within the bearingsby the projected area of the bearing surface. Due account is to be taken of dynamic


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loading and alignment when considering bearing pressures. The pressures are notto exceed those given in Table 4.2.

RPR 5.5 bar

Oil Lubricated White Metal 2.8 bar

Rubber 2.6 bar

Table 4.2 Bearing Pressures

4.1.8 Bearing Clearance

a . The bearing design diametral clearance, the maximum allowable clearance and theminimum permissible thickness of material remaining after wear are to be inaccordance with the manufacturers recommendations. For water lubricatedbearings the diametral clearance achieved during initial assembly must include themanufacturers recommended allowance for swelling after immersion. Reducedclearances are permissible where authorised by DPA.

4.1.9 Lubrication

a . Hydrodynamic lubrication is a function of shaft surface velocity (V) and bearingpressure (p) related to the bearing material and geometry. It is desirable that it isachieved and maintained throughout the shaft speed range and the bearingmanufacturer should provide information to establish the minimum hydrodynamicvelocity/pressure (V/p) ratio.

b . At low shaft speeds consideration may have to be given to reducing bearingpressures and/or increasing shaft rubbing speeds by increasing the bearingdiameter locally. This however, will depend upon the overall shaft design.

c . Rubber and reinforced phenolic resin stern tube bearings are to be lubricated with asea water supply taken from the sea water main or from a circulating pump at thepressure, flow and cleanliness parameters defined in the SRD.

4.1.10 Plummer Bearings General

a . Plummer bearings can be either bulkhead-mounted or of the pedestal type and mustbe positioned in accordance with the requirements of Def Stan 02304 Part 1.

b . Bulkhead bearings are to be attached by a circular spigotted flange to a seat built outfrom the bulkhead. Pedestal bearings are to be base or centre supported on a shipstructure seat.

c . Plummer bearing assemblies may incorporate a moveable spherical housing toaccommodate initial shaft operational misalignment and shock.

d . Plummer bearings are to be able to operate normally when submerged in sea waterto a depth of 5 m for at least 48 hours or as required in the SRD.

4.1.11 Seatings

a . The design of plummer bearing seatings is the responsibility of the ship designerwho is to take account of the shaft designers requirements.


14

b . Bulkhead-mounted bearings are to be mounted normal to the longitudinal axis ofthe shaft, as close to the supporting bulkhead as possible, and in such a way as toform an acceptable bulkhead seal.

c . Arrangements are to be provided for temporary shaft support during bearing refit,and for seating(s) in way of each plummer bearing for the hydraulic jack(s) used inmeasuring bearing loads.

d . All seatings and bearing securing arrangements are to conform to the shockrequirements specified in the SRD.

4.1.12 Plummer Bearing Types

a . The preferred type of bearing is the hydrodynamic, oil lubricated type.Alternatively a rolling contact type of bearing may be used if required by a specialduty.

4.1.13 Design Requirements

a . Hydrodynamic bearings are to:

(1) Be white metal lined to Def Stan 02839, either plain journal or pivot padtype;

(2) Be built of a number of identical segments arranged symmetrically about thevertical plane;

(3) Have a self-contained lubrication system unless specified otherwise;(4) Have adequate sealing against loss of lubricant;(5) Be provided with a dipstick to measure the static and running oil levels;(6) Be provided with a thermometer pocket for an approved glass bulbthermometer for local observations;

(7) Be provided with at least one bearing pad with a thermocouple to allowcontinuous monitoring of pad temperature by the ships in-built monitoringsystem;

(8) Have suitable connections and passageways for sea water cooling;(9) Be provided with a hole in the top bearing casing for fitting a temporarymicrometer poker-type weardown gauge. This hole will normally be plugged;

(10) Be long enough to ensure hydrodynamic lubrication at and above minimumservice speed subject to a maximum bearing pressure of 10 bar and a maximum L/Dratio of 1:1;

(11) Plummer bearing casings are to be either steel castings to Def Stan 02849 orfabricated from steel to Def Stan 02791.

b . Rolling contact bearings are to be:

(1) Of the fully floating expansion type;


15

(2) Supplied as a self-contained units;(3) Assembled with the inner race firmly clamped to the shaft and positionedcentrally in the outer race which is to be attached rigidly to the ships structure;

(4) Grease lubricated with adequate sealing against loss of lubricant;(5) Fitted with a spring loaded, micrometer graduated, bearing positionindicator, to monitor bearing axial drift.

4.2 Design Requirements Bulkhead Glands

4.2.1 General

a . The function of a bulkhead gland is to provide a water seal where the main shaftpasses through a main bulkhead. It is fitted where the bulkhead seal is not formedby a bulkhead mounted plummer bearing.

4.2.2 HM Surface Ships

a . The type of bulkhead gland to be fitted in HM Surface Ships will be decided by thelead shipbuilder to meet the SRD.

4.2.3 Submarines

a . In Submarines the bulkhead gland is to be a soft packed or lip seal gland type whichis to be watertight up to the design pressure of the bulkhead.

b . The design is to allow for the gland to be removed for refit with the shaft in-situ andthe size of the remaining bulkhead aperature is to be in accord with the shaftwithdrawal arrangements.

4.3 Stern Seals

4.3.1 General

a . The function of the stern seal is to eliminate or reduce to a minimum the ingress ofwater into the vessel where the propeller shaft penetrates the hull.

b . Stern seals generally comprise:

(1) A stationary housing attached to the hull and surrounding the propeller shaft;(2) An inner annulus, usually the shaft sleeve, attached to and rotating with theshaft;

(3) Sealing elements interposed between the housing and the inner annulus.c . Stern seals are to be of the axially directed face type. Soft packed glands are to be

used only when specified in the SRD.

d . In cases where a manually operated soft packed gland is specified in conjunctionwith a face type seal, the soft packed gland is for emergency use only, but its designis to conform to the requirements of this standard.


16

4.3.2 General Design Requirements

a . Stern seals are to be designed to limit the ingress of sea water to 25 litres/hour. Thisleakage rate is to be achieved under the most adverse conditions with the shaftrotating in either direction at any speed between zero and the maximum speedspecified in the SRD. If the leakage rate reaches 10 times the design leakage rate theseal is to be considered to have failed.

b . Each stern seal assembly is to incorporate an air-operated inflatable seal at its aftend to allow maintenance and repair to be carried out without the need for dockingthe vessel. Permanent facilities are to be provided for inflation of this seal and itsdesign is to be such that it is clear of the shaft when not in use. The required airpressure for operation of the inflatable seal is to be specified by the seal designer.

c . Stern seals must function under all specified shaft misalignments including thoseencountered between new and fully worn outboard bearings.

d . Stern seals are to be designed to allow refit of the sealing and other wearingelements with the shaft in place.

e . Secondary sealing by O rings or other elastomeric means is to be provided at allcircumferential and radial joints and interfaces which may constitute a leakagepath.

f . Where elastomeric seals are fitted with loose ends to comply with therequirements of Clause 4.3.2d the loose ends are to be bonded together afterfitting to form an unsplit seal.

g . Where the seal housing assembly includes both radial and longitudinal joints, thelongitudinal joints of adjacent housing components are to be displaced from oneanother to eliminate a direct leakage path.

h . Stern seals are to be designed to accommodate all axial, transverse and angularshaft movements during normal operation and under shock conditions, as definedin the SRD without damage or loss in efficiency.

i . Where the rotating components of face-type seals are fitted to the shaft sleeve withpositive means of axial location, such as by grooves machined in the sleeve, meansare to be provided for adjusting the relative axial positions of the rotating andnon-rotating components during assembly.

j . The shaft sleeve is to extend axially forward and aft of the complete seal housingassembly including the soft packaged gland housing and splashguard where fitted.The shaft sleeve is to extend far enough forward to allow visual inspection of theshaft/sleeve interface at any time. A thrower ring may be fitted to the sleeve toprevent leakage water reaching this interface.

k . A supply of filtered sea water is to be arranged for lubrication and cooling of therubbing surfaces. The seal design is to be such that it is to be capable of operationwith an unfiltered supply of sea water direct from the sea on failure of the filteredsupply.

l . The materials used for the construction of stern seals are to be selected to minimizecorrosion and wear and in particular to minimize crevice corrosion in the region ofsecondary sealing arrangements.


17

4.3.3 Design Requirements for HM Surface Ship Stern Seals

a . Stern seals for HM Surface Ships are to be of the mechanical face type or of theelastomeric face type. Unless otherwise specified, only a single sealing face isrequired.

b . Where the seal is of the elastomeric face type the seal housing is to incorporate aspare sealing element not in use.

c . Stern seals for HM Surface Ships are to be designed to operate with a cooling watersupply pressure of 1.4 bar. The required flow and standard of filtration are to bestated by the seal designer.

4.3.4 Design Requirements for Submarine Stern Seals

a . Stern seals for Submarines are to incorporate two sealing elements of the partiallybalanced mechanical face type in tandem, one working and one idling. The forwardseal will be working in normal operation. The design is to be such that the aftelement can be brought into use as the working element when required. Other typesof seal will be considered if they can be proved to provide the same degree ofintegrity, e.g. shock and duty.

b . Stern seals for Submarines are to be designed to operate with a cooling water supplypressure equal to the Depth Dependent Systems Test Pressure (DDSTP) as definedin the SRD. The required flow and standard of filtration are to be specified by theseal designer.

c . The seal designer is to submit calculations to demonstrate that the elastic behaviourof the mechanical face type seal components, when subjected to any sea waterpressure up to the DDSTP as defined in the SRD, is such as to achieve satisfactoryface control throughout the operational range of the Submarine.

d . The inflatable seal in Submarine stern seals is to operate effectively when the seal isimmersed to a depth of 10 m.

e . Stern seals for Submarines are to incorporate a manually operated soft packedgland, capable of the duty specified in the SRD, in addition to and forward of themechanical face type seals for use in emergency on failure of the mechanical facetype seals.

f . The housings for Submarine mechanical face type stern seals are to be designedwith no horizontal joint and are to meet the requirements, including shock duty, ofcomponents attached to the Submarine pressure hull as defined in the SRD.

4.3.5 Design Requirements for Soft Packed Glands

a . Soft packed glands are to consist of a stuffing box and gland ring. Lantern rings areto be provided, where necessary, for the admission of lubricant.

b . A choke ring type emergency seal should be fitted between the packed gland andforward main shaft seal if specified in the SRD.

c . The dimensions of soft packed glands are to permit the use of metric naval storestandard packings wherever possible.


18

d . Gland studs are not to be screwed into blind tapped holes. The gland is to beprovided with adjusting nuts by which the axial position of the gland ring can beadjusted to tighten or loosen the gland packing. The gland is to be provided withstops to prevent excessive withdrawal of the gland ring in service. The gland is to becapable of adjustment with the shaft rotating or stationary.

e . Where a manually operated soft packed gland is specified as the principal stern seal,it is to be provided with an adjusting mechanism to ensure equal and simultaneousrotation of the gland ring adjusting nuts by means of worm or tooth drives. Theadjusting mechanism is to be designed to tighten the gland by clockwise rotation ofthe manual drive input.

f . Adequate clearance is to be provided adjacent to each gland to allow the gland ringto be withdrawn completely over the gland bolts to allow access for the extractionof packing from the bottom of the gland.

g . Where a soft packed gland is specified for emergency use only, it is to be designedto enable the clearance between the gland packing and the shaft sleeve to bechecked when the gland is not is use, and to avoid fouling the shaft under normalshaft movement, e.g. bearing weardown, etc.

4.4 Shaft Brake and Locking Gear

4.4.1 Shaft Brake General

a . The function of the shaft brake is to slow down and restrain the shaft whilst the shipis being manoeuvred at slow speed and to hold the shaft while the shaft locking gearis being engaged.

b . The shaft brake is to be of the disc caliper type. This is to have a rotating disc fittedeither between adjacent shaft flanges or on the forward end of the main gear wheelshaft. Friction pads are to be arranged in pairs, one on either side of the disc, andthese are to be held in caliper assemblies supported from the ships structure. Thebrake is to be operated by pneumatic or hydraulic pressure which forces the captivepads against the rotating disc. There is to be no resultant movement of the shaftwhen the brake is applied, i.e. movement of the pads is to be symmetrical.

c . The following information must be supplied to the brake manufacturer:

(1) Maximum shaft speed at which brake will be applied;(2) Maximum stopping time required;(3) Inertia torque of the rotating system;(4) Engine drive torque during application;(5) Trailing propeller torque;(6) Expected frequency of application;(7) Relative displacement between disc and pads due to shaft movements duringnormal operation and during underwater shock.


19


a . The shaft brake is to be:

(1) Easy to operate;(2) Designed with automatic pad wear adjustment;(3) Provided with primary and secondary operating air or hydraulic services;(4) Provided with controls to prevent misuse and to keep torque build-up, torquedecay and energy dissipation within the design limits;

(5) Able to operate normally in a depth of sea water of 5 m;(6) Designed so that in the event of a controls failure the brake is OFF;(7) Designed for refit by replacement with the shaft in-situ.

b . In installations where the brake duties are moderate, drum brakes or hand operatedband brakes may be used subject to the approval of DPA.

4.4.3 Shaft Locking Gear - General

a . The function of the propeller shaft locking gear is to immobilize the shaft whilst theship is underway - either powered by its remaining shaft(s) or being towed - andduring shaft maintenance or inspection.

b . The locking gear is to be made integral with the main turning gear or incorporatedin the shaft brake housing but it must be capable of independent operation.

c . If locking the shaft through the turning gear involves risk to the gearing, especiallywhen the ship is underway, then an alternative locking arrangement is to be made byproviding a mechanical tie between the shaft and the ships structure.


a . The locking gear is to be easy to apply with the shaft in any position and must holdthe shaft and gearing stationary against at least 50 per cent of the full power aheadtorque.

4.5 Thrust Block Bearings

4.5.1 General

a . The function of a thrust block is to transmit propeller thrust to the hull of the shipand to control shaft axial movement.

b . The thrust block may be integral with the main gearbox of propulsion machinery orindependently mounted on the ships structure.

c . Independently mounted thrust blocks may incorporate a main shaft bearing of theplain or pivoted pad type. This bearing is to satisfy all the plummer bearingrequirements specified in Clause 4.1.


20

d . Temporary support of the thrust shaft is needed during assembly, transport andstorage and shaft alignment where the thrust block has only one or no journalbearings.

e . Any thrust block positioned adjacent to a flexible main shaft coupling is to have ajournal bearing fitted forward of the thrust collar.

4.5.2 Seatings

a . Thrust block seatings are the responsibility of the ship designer who must takeaccount of the requirements of the shaft designer and thrust block manufacturer forrigidity and securing arrangements.

b . The ship designer is to supply the thrust block manufacturer with the followinginformation:

(1) Conditions of axial thrust and associated shaft speeds;(2) An indication of whether the axial thrust condition is continuous or transient;(3) Preferred grade of lubricating oil to be used in the block;(4) Any other relevant information such as shaft rake and type of mountingrequired.

c . The ship designer will then obtain from the thrust block manufacturer:

(1) A graph of righting moment versus running misalignment between collarand pads. Righting moment is defined as being that moment developed by thehydrodynamic oil film generated at the tilting thrust pads and resisting a bendingmoment applied at the thrust collar;

(2) The maximum allowable running misalignment between collar and padsmeasured across the collar diameter;

(3) An estimate of the rotation which occurs within the casing of the thrust block.d . The ship designer is to calculate the thrust collar rotational stiffness for the shaft

configuration and using the righting moment (obtained from graph described inClause 4.5.2c (1)) is then to calculate thrust collar rotation. Thrust collar rotation isdefined as the misalignment of the thrust collar relative to the shaft centre-linewhen subject to a moment about an axis perpendicular to the shaft axis.

e . The resultant misalignment of the thrust collar relative to the thrust pads, which isthe algebraic sum of the thrust collar rotation and the deflection of the seating andcasing, must not exceed the maximum running misalignment as defined in Clause4.5.2c (2).


a . The thrust block is to:

(1) Be lubricated from the ships main machinery lubrication system unlessspecified otherwise in the SRD. Where the thrust block is lubricated from the main


21

forced lubrication system, the supply is to enter at the bottom of the casing and exitfrom the top of the casing then be led via a closed sight flow indicator to the draintank;

(2) Operate normally when submerged to a depth of 5 m of sea water for at least48 hours or as may be required in the SRD;

(3) Be provided with seals to prevent ingress of water and loss of lubricant. Theseals selected are to be of a type which will cause minimum wear on the shaft;

(4) Accept at full power, athwartship and vertical shaft movements as defined inthe SRD;

(5) Be designed for refit by replacement with the shaft in-situ;(6) Be provided with local and remote temperature surveillance equipment;(7) If a journal bearing is fitted to the thrust block the top casing is to be providedwith a suitable plugged hole to accommodate a temporary, poker type, micrometerweardown gauge.

b . In HM Surface Ships, the thrust block is to be designed to withstand 150 per centfull power thrust as a steady load in both directions and between 150 per cent and200 per cent for periods up to 15 seconds or as defined in the SRD.

c . In Submarines, the thrust block is to be designed to withstand the axial componentof shaft and propulsor weight at all permissible angles of trim, when added to thethrust caused by any of the following conditions:

(1) Hydrostatic thrust at Deep Diving Depth (DDD) plus 180 per cent of fullahead power propulsive thrust;

(2) The full astern power propulsive thrust when surfaced;(3) The resultant of the hydrostatic and propulsive thrusts caused by rotation ofthe shaft in either direction at Minimum Collapse Depth (MCD) at any shaftspeed between zero and the shaft speed specified in the SRD. The manufacturer isto state if jacking oil is required in these conditions.

4.5.4 Thrustmeter/Resonance Changer

a . The thrust block is to incorporate internal seats, cylinders and oil routes as requiredfor the installation of a thrust meter and resonance changing equipment.

4.5.5 Trailing Thrust Bearing

a . Where there is a requirement to trail a shaft that is disconnected from the drive unitand, for geographical reasons, the break can only be made downstream of the thrustblock, a separate trailing thrust bearing is to be provided. This is to be made integralwith a pedestal plummer bearing in the form of a ring of small thrust pads fitted atthe forward end which work against a trailing thrust collar on the shaft. Bearingclearances are to be sufficient to render the bearing inoperable during normalrunning while ensuring that, in the trailing condition, the axial drift of the shaftingis still acceptable.


22

4.6 Thrustmeters

a . Unless otherwise specified, the thrust blocks in the first ship of any class, are to beprovided with a thrustmeter. Provision is to be made for other ships in the class to befitted with a thrustmeter if required.

b . The thrustmeter is to be capable of measuring continuously the actual thrust of theshaft when running ahead or astern.

4.7 Resonance Changers

4.7.1 General

a . Resonance changers are to be fitted to those ships which are fitted withthrustmeters. Other ships are to be fitted for, but not with, resonance changers.

b . The function of the resonance changer is to vary the stiffness of the thrust bearing toattenuate unacceptable vibrations which can occur when the natural frequency ofthe propeller shaft coincides with the frequency of the propeller pulsations.

c . The resonance changer is to consist of a number of oil filled pressure vesselsconnected via regulating valves and tuning pipe(s) to the supply line between thethrust block and a hydraulic control panel.

d . The control panel is to incorporate a power driven pump which maintains acontinuous oil flow from the reservoir, through the thrustmeter and back, via a shaftmovement limit valve.

e . The control panel is to be fitted with a hand operated pump to act as backup in theevent of failure of the power driven pump.

f . The compressive modulus of the oil contained in the pressure vessels provides acushion to reduce the thrust bearing effective housing stiffness. The regulatingvalves allow the stiffness to be varied to suit all operating conditions.

4.7.2 Design Procedure

a . The following simplified design procedure is to be followed when selectingresonance changing equipment:

Let Ao = Total area of thrust pistons (m2)B = Bulk modulus of oil (Ns/m2)p = Density of oil (kg/m3)q = Ratio of shaft stiffness to oil in resonance changer bottles (0.3) = Dynamic viscosity of oil (Ns/m2)Ko = Combined stiffness of shaft and thrust block (N/m)Wc = Natural axial frequency of shaft (rad/s)Vmin = Minimum volume of oil vessel (m3)


23

V = Volume of actual selected oil vessel (m3)L = Length of tuning pipe (m)d = Pipe bore diameter (m)dm = Minimum diameter of pipe bore (m)

NOTE: These symbols are used in the following analysis:

(1) Evaluate the minimum oil vessel (standard air bottle) volume fromVmin Ao

2Bq

Ko

whereq 0.3

(2) Select the largest practical size standard air bottle V such that V Vmin.

(3) Determine a value for Ld2

for selected volume V from

Ld2

B

4Wc2pV

(4) Choose a convenient Length L and diameter d consistent with the value ofLd2

determined above whilst still satisfying

d dm 82

Wcp q(6 q 8q q2)or

d dm 81.3

Wcp ifq 0.3asrecommended

If this is not practical repeat with a revised value of V.

4.8 Shaft Earthing and Cathodic Protection Devices

4.8.1 General

a . The design of shaft earthing and cathodic protection devices is to conform to DefStan 02704.

b . Shaft earthing and cathodic protection devices are to be fitted only when specifiedin the SRD or when requested by DPA.

4.8.2 Interface Requirements

a . The shaft interface unit is to be designed:

(1) For refit by replacement with the shaft in-situ;


24

(2) To withstand fore aft and angular shaft movements defined in the SRD;(3) So that no special setting up or alignment is required;(4) To prevent any shaft wear or scuffing at the interface;(5) To be submerged in water without causing electrical short circuit;(6) So that radiated noise does not interfere with active or passive sonar system;(7) So that it will not compromise the integrity of the tailshaft inboard protectivecoating.

4.9 Shaft Interface for Shaft Driven Auxiliaries

4.9.1 General

a . Shaft driven auxiliaries are only to be fitted when specified in the SRD or with thewritten approval of DPA.

b . The propeller shaft auxiliary drive is that equipment which attaches around theshaft to provide the power transfer to the auxiliary machine.

c . The drive can be gear, chain sprocket or friction belt, and is preferably to beattached to a shaft flange coupling.


a . The auxiliary drive shaft interface unit is to be designed:

(1) For refit by replacement with the shaft in-situ;(2) To withstand fore and aft and angular shaft movements defined in the STR;(3) So that no special setting up or alignment is required;(4) To prevent any shaft wear or damage;(5) With a fail-safe device to prevent shaft or gearbox damage in the event ofauxiliary machinery seizure.

5. CORPORATE KNOWLEDGE AND EXPERIENCERelated Documents: There are no Related Documents in this section.

5.1 Special Service Air Transfer Box

5.1.1 General

a . Where special service air (Agouti) is required the supply of compressed air is to beled down the shaft bore to passageways in the propeller hub leading to the propellerblades. Alternatively the air supply may be taken directly into the propeller hub viaa pipe led down the A-bracket support arm.


25

b . The function of the air transfer box is to provide a seal between the air supply pipeand the rotating shaft or hub.

c . The air transfer box can be arranged to fit over the shafting or at the forward end ofthe main gearwheel as appropriate.

d . The inboard air transfer box is attached around an appropriate shaft coupling flangewhich contains radially holes drilled through to the shaft bore. It consists of aninner sleeve bolted to, and rotating with the flange, and this is surrounded by astationary casing into which the compressed air is fed. Between casing and sleeveare water-lubricated seals which prevent the escape of air.

e . The outboard air-transfer box is positioned around the shaft between the mainA-bracket and the propeller hub. It consists of an inner sleeve with internal airpassages which is bolted to the propeller hub, and an outer casing anchored to theA-bracket barrel. Between casing and sleeve there are seals to contain the airbearings to support the casing.


a . The Agouti air transfer box is to be designed:

(1) To provide a seal such that the agouti air leakage does not exceed 1 per cent byvolume;

(2) For refit by replacement with the shaft in-situ;(3) To withstand the fore, aft and angular shaft movements defined in the SRD;(4) So that no serious shaft wear, scuffing or shaft damage can occur should the

rotating elements seize.

b . The air box design documentation is to specify all services required such as coolingwater - its supply pressure, flow and cleanliness - and these must be reflected in theSRD.

c . Services vital to the air box are to be:

(1) Interlocked with a control system to ensure availability when required;(2) Provided with system failed warning devices both local and remote as

necessary.

d . Inboard air boxes, in addition are to be:

(1) Designed so that the cooling water contamination of the Agouti air does notexceed 1 per cent by volume;

(2) Provided with emergency sealing arrangements to prevent flooding via theshaft when it is stationary.

5.1.3 Design Information

a . The following information is to be given to the Contractor when ordering the airbox:


26

(1) Maximum and minimum air pressures as supplied and when self-venting;(2) Maximum and minimum air flow and temperature;(3) Maximum ahead and astern shaft speed;(4) Shaft diameter and flange dimensions;(5) Shaft movements.

DEF STAN 02304 Part 2/Issue 2(NES 304 Part 2)

27

ANNEX A.

RELATED DOCUMENTSA1. The following documents and publications are referred to in this Defence Standard:

BS EN 1563 Founding, spheroidal graphite cast iron.

BS EN 1564 Founding, Austempered ductile cast irons.

BS EN 20286 ISO system of limits and fits:

Part 1: Bases of tolerances, deviations and fits;

Part 2: Tables of standard tolerances, grades and limitsdeviations for holes and shafts.

BS 1134 Assessment of Surface Texture:

Part 1: Methods and Instrumentation;

Part 2: Guidance and General Information.

BS 1916 Limits and Fits for Engineering:

Part 1: Limits and tolerances;

Part 2: Guide to the selection of fits in BS 1916: Part 1;

Part 3: Recommendations for Tolerances, Limits and Fits forlarge diameters.

BS 4500 ISO Limits and Fits:

Part 1: General Tolerenances and Deviations;

Part 4: Specification for system of cone (taper) fits for conesfrom C = 1:3 to 1:500, lengths from 6 mm to 630 mm;

Part 5: Specification for system of cone tolerances for conicalworkpieces from C = 1:3 to 1:500 and lengths from6 mm to 630 mm.

ENGJS35022

JSP 430 MOD Ship Safety Management System Handbook:

Volume 1: Policy and Guidance on MOD Ship and EquipmentSafety Management.

Def Stan 02-304

(NES 304)

Shafting Systems and Propulsors:

Part 1: Design Requirements for Main Propulsion Shafting.

Def Stan 02-352

(NES 352)

Second Machinery Inspection and Contractors Sea Trials ofPropulsion Machinery in HM Surface Ships.

Def Stan 02-362

(NES 362)

Type and Production Testing of Mechanical Equipment.

Def Stan 02-704

(NES 704)

Requirements for Cathodic Protection:

Part 1: Systems General;

Part 2: Impressed Current Cathodic Protection System;

Part 3: Sacrificial Anode or Selfenergised System;

Part 4: Ships Fitting Out, Ships in Refit or Laidup;

Part 5: General Information on BiMetallic Couples.

Def Stan 02-722

(NES 722)

Requirements for the Preperation, Identification andManagement of Drawings.


28

Def Stan 02-723

(NES 723)

Requirements for Marker Plates.

Def Stan 02-745

(NES 745)

Classification, Inspection Requirements and AcceptanceStandards for Castings:

Part 2: Steel Castings.

Def Stan 02-747

(NES 747)

Requirements for Nickel Aluminium Bronze Castings and Ingots:

Part 1: Nickel Aluminium Bronze Naval Alloy CentrifugallyCast;

Part 2: Nickel Aluminium Bronze Naval Alloy Ingots andSand Castings with Welding Permitted to the WettedSurface;

Part 3: Nickel Aluminium Bronze Commercial Alloys Ingotsand Sand Castings;

Part 4: Nickel Aluminium Bronze Naval Alloy Sand Castingswith Welding Restricted to the NoWetted Surface(Class 1 and 2) Castings only;

Part 5: Design and Manufacture of Nickel Aluminium BronzeSand Castings (RestrictedCommercial).

Def Stan 02-772

(NES 772)

Welding of Ferrous and Non Ferrous Metallic Materials.

Def Stan 02-791

(NES 791)

Requirements for Weldable Structural Steels:

Part 1: Mild SteelPlate Sections and Bars;

Part 2: Notch Tough Mild SteelPlate;

Part 3: B Quality Steel Plates and Sections;

Part 4: BX Quality Steel Plates.

Def Stan 02-839

(NES 839)

Requirements for White Metal Ingots.

Def Stan 02-849

(NES 849)

Steel Castings for Structural, Engineering and PressurePurposes.

Def Stan 02-863

(NES 863)

Requirements for the Classification, Dimensions, Tolerances andGeneral Standards of Acceptance for Copper and Nickel AlloyCastings.

Def Stan 08-123

(NES 1004)

Requirement for Design and Testing of Equipments to MeetEnvironmental Conditions (UK Restricted).


29

ANNEX B.

ABBREVIATIONS AND DEFINITIONS

B1. For the purpose of this Defence Standard the following abbreviations apply:

BR Book of Reference(s) (as the context requires)

BS British Standard(s) (as the context requires)

DDD Deep Diving Depth

DDSTP Depth Dependent Systems Test Pressure

DLO Defence Logistics Organisation

DPA Defence Procurement Agency

HM Her Majesty

ISO International Standards Orgasnisation

L/D length to diameter

m metre

mm millimetre

MCD Minimum Collapse Depth

MOD Ministry of Defence

MOD(N) Ministry of Defence (Navy)

Ni Al Br Nickel Aluminium Bronze

NATO North Atlantic Treaty Organisation

NES Naval Engineering Standard(s) (as the context requires)

p Pressure

RPR Reinforced Phenolic Resin

SRD System Requirement Document

SW Sea Water

V Velocity

V/p Velocity to pressure

B2. For the purpose of the Defence Standard the following definitions apply:

Machinery All propeller shafts, propulsors and shafting auxiliaries aftof the main gearing output flange. Equipments such asthrust blocks, which sometimes form part of the maingearbox, are also included.


30

ANNEX C.

PROCUREMENT CHECK LIST

Notes:

1. This Check List is to ensure that certain aspects of this Defence Standard are consulted

when preparing a procurement specification for a particular application.

2. Clauses where a preference for an option is to be used or where specific data are to be added

are included in the Check List.

3. Each item is to be marked either:

= included

NA = not applicable

CheckNo. Check Clause No. or NA

1 Specify as made process masters to be supplied bycontractor.

3.2.b

2 List ancillary assemblies to be supplied by MOD. 3.3e

3 Define pressure flow and cleanliness parameters for seawater supply to sterntube bearings.

4.1.9c

4 Specify submergence requirement for plummer bearings. 4.1.10d

5 Specify shock requirements for plummer bearingseatings.

4.1.11d

6 Specify type of stern seal. 4.3.1c

7 Define shaft movements for stern seals. 4.3.2h

8 Specify No of sealing faces for HM Surface Ship sternseals.

4.3.3a

9 Define requirements for components attached tosubmarine pressure hull.

4.3.4f

10 Supply design information to shaft brake manufacturer. 4.4.1c

11 Specify thrust block lubrication arrangements. 4.5.3a

12 Specify maximum shaft speed for operation at MCD. 4.5.3c

13 Specify all services for air emission system air transferbox.

5.1.2b

14 Supply design information to contractor:

a. Air emission pressure and temperature;b. Air flow;c. Shaft speed;d. Shaft dimensions;e. Shaft movements.

5.1.3a

15 Specify whether shaft earthing or cathodic protectiondevices are required.

4.8.1b

16 Define shaft movements for shaft driven auxiliaries. 4.9.2a

17 Specify the extent of equipment and subassemblymarking.

3.4.6a


31

AAir box, design requirements, 25

Air transfer box, design requirements, 25

Air transfer box, general, 24, 25

BBearing, clearance, 13

Bearing, hydrodynamic design requirements,14

Bearing, length/dia ratio, 12

Bearing, plummer types, 14

Bearing, plummer, general, 13

Bearing, pressures, 12

Bearing, rolling contact, 14

Bearing, thrust blocks general, 19, 20

Bearing, thrust blocks, design requirements,20, 21

Bearing, trailing thrust, 21

DDrawings, preparation, 8

EEnvironmental conditions, 8

FFinish, 9

GGland bulkhead general, 15

Gland bulkhead submarines, 15

Gland bulkhead, surface ships, 15

Gland soft packed, design requirements, 17,18

IInstallation, 9

Installation and trials, manufacture, general,8

LLimits and fits, 9

Lubrication, 9, 13

MMain shaft bearings, general, 10

Marking, 9

Materials, 8

Materials, alternative, 12

RResonance changer, design procedure, 22

Resonance changer, general, 22

SScope, 2

Seals, stern, design requirements, 16

Seals, stern, general, 15

Seals, stern, submarine design requirements,17

Seals, stern, surface ships design requirements, 17

Seatings, 9, 13, 14, 20

Shaft brake and locking gear, general, 18

Shaft brake design requirements, 19

Shaft earthing and cathodic protection devices, general, 23

Shaft interface auxiliary drive, 24

Shaft interface for shaft driven auxiliary, general, 24

Shaft interface requirements, 23

Shaft locking gear, design requirements, 19

Shaft locking gear, general, 19

Stern tube and bracket bearing barrels, 10


32

Stern tube and bracket bearing bushes, 10,11

Stern tube and bracket bearings - preferredtypes and materials, 11, 12

TTesting, 9

Thrustmeter/resonance changer, 21

Thrustmeters, 22

Trials, 9

WWelding, 9

Inside Rear Cover

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Copying Only as Agreed with DStan

Defence Standards are Published by and Obtainable from:

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File Reference

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Revision of Defence Standards

Defence Standards are revised as necessary by up issue or amendment. It is important thatusers of Defence Standards should ascertain that they are in possession of the latest issue oramendment. Information on all Defence Standards is contained in Def Stan 00-00 Standardsfor Defence Part 3 , Index of Standards for Defence Procurement Section 4 Index of DefenceStandards and Defence Specifications published annually and supplemented regularly byStandards in Defence News (SID News). Any person who, when making use of a DefenceStandard encounters an inaccuracy or ambiguity is requested to notify the Directorate ofStandardization (DStan) without delay in order that the matter may be investigated andappropriate action taken.

CONTENTSTITLE PAGESCOPEFOREWORDSponsorshipConditions of ReleaseCategories of Defence StandardsRelated DocumentsHealth and SafetyAdditional Information

1. PERFORMANCE SPECIFICATION2. NATIONAL/INTERNATIONAL REGULATIONS3. MILITARY STANDARDS/REQUIREMENTS3.1 Environmental Conditions3.2 Drawings3.3 Materials3.4 Manufacture, Installation and Trials3.4.1 General3.4.2 Welding3.4.3 Seating3.4.4 Limits and Fits3.4.5 Finish3.4.6 Marking3.4.7 Testing3.4.8 Installation3.4.9 Trials

4. DESIGN REQUIREMENTS/GUIDANCE4.1 Main Shaft Bearings4.1.1 General4.1.2 Stern Tube and Bracket Bearing Barrels4.1.3 Stern Tube and Bracket Bearing Bushes4.1.4 Stern Tube and Bracket Bearings - Preferred Types and Materials4.1.5 Alternative Bearing Materials4.1.6 Bearing Length/Diameter RatioTable 4.1 Length to Diameter Ratio4.1.7 Bearing PressuresTable 4.2 Bearing Pressures4.1.8 Bearing Clearance4.1.9 Lubrication4.1.10 Plummer Bearings General4.1.11 Seatings4.1.12 Plummer Bearing Types4.1.13 Design Requirements

4.2 Design Requirements Bulkhead Glands4.2.1 General4.2.2 HM Surface Ships4.2.3 Submarines

4.3 Stern Seals4.3.1 General4.3.2 General Design Requirements4.3.3 Design Requirements for HM Surface Ship Stern Seals4.3.4 Design Requirements for Submarine Stern Seals4.3.5 Design Requirements for Soft Packed Glands

4.4 Shaft Brake and Locking Gear4.4.1 Shaft Brake General4.4.2 Design Requirements4.4.3 Shaft Locking Gear - General4.4.4 Design Requirements

4.5 Thrust Block Bearings4.5.1 General4.5.2 Seatings4.5.3 Design Requirements4.5.4 Thrustmeter/Resonance Changer4.5.5 Trailing Thrust Bearing

4.6 Thrustmeters4.7 Resonance Changers4.7.1 General4.7.2 Design Procedure

4.8 Shaft Earthing and Cathodic Protection Devices4.8.1 General4.8.2 Interface Requirements

4.9 Shaft Interface for Shaft Driven Auxiliaries4.9.1 General4.9.2 Design Requirements

5. CORPORATE KNOWLEDGE AND EXPERIENCE5.1 Special Service Air Transfer Box5.1.1 General5.1.2 Design Requirements5.1.3 Design Information

ANNEX A. RELATED DOCUMENTSANNEX B. ABBREVIATIONS AND DEFINITIONSANNEX C. PROCUREMENT CHECK LISTALPHABETICAL INDEX