2699_245_A (1).pdf

REV

TECHNICAL PUBLICATION

DATE: CURRENT VERSION:

TP: 2699

HULL, MECHANICAL, & ELECTRICAL

CONTROLLABLE PITCH PROPELLER SYSTEM

MULTIPLE MANUFACTURERS

SWBS 245

DISTRIBUTION STATEMENT D - Distribution authorized to DHS, USCG, DoD and their contractors to protect publications required for official use or for administrative or operational purposes only; determined on 15 JUL 1985.

Other requests for this document shall be referred to Commander, USCG Surface Forces Logistics Center, ESD –Tech Info Mgmt Br, 2401 Hawkins Point Road, M/S 25, Baltimore, MD 21226.

WARNING - This document contains technical data whose export is restricted by the Arms Export Control Act (Title22, U.S.C., Sec 2751, et seq.) or the Export Administration Act of 1979, as amended, Title 50, U.S.C., App.

2401et seq. Violations of these export laws are subject to severe criminal penalties. Disseminate in accordance with provisions of DoD Directive 5230.25.

DESTRUCTION NOTICE - For unclassified, limited documents, destroy by any method that will prevent disclosure of contents or reconstruction of the document.

PUBLISHED UNDER AUTHORITY OF THE U.S. COAST GUARD

15 JUL 1985 01 JAN 2023

FULL EXPORT-CONTROL WARNING STATEMENT

NOTICE TO ACCOMPANY THE DISSEMINATION OF EXPORT-CONTROLLED

TECHNICAL DATA

Export of the attached information which includes, in some circumstances, release to foreign nationals within the United States, without first obtaining approval or license from the Department of State for items controlled by the International Traffic in Arms Regulations (ITAR) or the Department of Commerce for controlled by the Export Administration Regulations (EAR), may constitute a violation of the law.

Under 22 U.S.C. 2778, the penalty for unlawful export of items or information controlled under the ITAR is up to 20 years imprisonment, or a fine of $1,000,000 or both. Under 50 U.S.C., Appendix 2410, the penalty for unlawful export of items or information controlled under the EAR is a fine of up to $1,000,000, or five times the value of the exports, whichever is greater, or for an individual, imprisonment of up to 10 years, or a fine of up to $250,000, or both.

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United States Coast Guard Surface Forces Logistics Center

2401 Hawkins Point Road Baltimore, MD 21226 Phone: (410) 582-4725 Fax: (410) 762-6898

26 FEB 2018

MEMORANDUM

From: Mitch Frid, Branch Chief

SFLC-ESD-TIMB

Reply to Attn of:

SFLC-ESD-TIMB-PPDS

R. Infantino

To: Distribution

Subj: Coast Guard Amendment No. 5 for Technical Publication 2699

Ref: (a) SFLC Central Activity 25571, dated 13 DEC 2017

1. PURPOSE. IAW ref (a), this memorandum amends Technical Publication 2699, Controllable Pitch Propeller System, by updating information. This technical publication is applicable to the 270‘ WMEC (A) Class Cutters.

2. PUBLICATION AFFECTED. Technical Publication 2699

3. ACTION.

a. Technical Publication 2699 is being amended to update heat exchanger information and adding zinc drawing. This technical publication is affected by updating part numbers on the Hydraulic Oil Cooler Drawing and adding Protector Rod Assembly Drawing in Appendix F.

b. Remove and insert pages as indicated below:

REMOVE INSERT

Cover Page Cover Page Technical Manual Deficiency/Evaluation

Report Technical Manual Deficiency/Evaluation

Report Individual Manual Application Sheet Individual Manual Application Sheet Appendix F - DWG 5 126 04 036 002, Hydraulic Oil Cooler Appendix F - DWG 5 126 04 036 002, Hydraulic Oil Cooler DWG 4 590 06 001 005, Protector Rod

Assembly (After Appendix F - DWG 5 126 04 036 002, Hydraulic Oil Cooler)

4. DISTRIBUTION. No paper distribution of this amended technical publication will be provided. An electronic amended master technical publication is maintained by SFLC-ESD-TIMB and is located in the Coast Guard Logistics Information Management System – Surface Technical Information Portal (CGLIMS-STIP) at http://oscls-lims-ap04.osc.uscg.mil:7002/NETIMS/. Additionally, the amendment package is available for viewing in CGLIMS-STIP by selecting the Amendments tab in the Technical Publication Detail page; it may be printed to update any hard copy. Annual distribution of all technical data will be distributed via DVD format to each associated unit; the Distribution Schedule is located under the View tab in CGLIMS-STIP. Additional DVDs and hard copies can be ordered via CGLIMS-STIP using the Document Ordering System.

FRID.MITCHELL.1043294772

Digitally signed by FRID.MITCHELL.1043294772 DN: c=US, o=U.S. Government, ou=DoD, ou=PKI, ou=USCG, cn=FRID.MITCHELL.1043294772 Reason: I am approving this document Date: 2018.02.26 14:15:29 -05'00'

Subj: Coast Guard Amendment No. 5 for Technical Publication 2699 9086

26 FEB 2018

5. REQUEST FOR CHANGES. The technical publication includes a Technical Manual Deficiency/Evaluation Report which links to the CG-22 process. Please use this form to report any discrepancies to the Product Line. All approved changes will be provided by the Product Line for inclusion in the technical publication.

6. REQUEST FOR FEEDBACK. The Surface Forces Logistics Center is very interested in your thoughts regarding this technical information package. Please take a few moments, using the link to the Customer Survey Form below, to let us know your thoughts. Every survey will be reviewed with the intention of making our products and services a valuable resource for your future use.

SFLC Customer Survey and Suggestion Form

DISTRIBUTION – SDL No. 167 a b c d e f g h i j k l m n o p q r s t u v w x y z A X B X C X X D E F G H

25 March 2016

CONTROLLABLE PITCH PROPELLER SYSTEM

SWBS GROUP(S) 245

UNITED STATES COAST GUARD

270’ WMEC (A) CLASS CUTTERS

Coast Guard Amendment No. 4 for Technical Publication 2699

1. PURPOSE: The purpose of this Amendment is to update information contained in Technical Publication 2699, Controllable Pitch Propeller System.

2. PUBLICATION(S) AFFECTED: Technical Publication 2699

3. INFORMATION: Technical Publication 2699 is amended to add information for relief valves and refer users to Coast Guard Logistic Information Management System – Surface Technical Information Portal (CGLIMS- STIP) for applicable Coast Guard Drawings. This technical publication is affected by adding Appendix J, Relief Valves, and removing the Foldout Coast Guard Drawings. This information is applicable to the 270’ WMEC (A) Class Cutters.

4. ACTION:

a. Remove and insert pages as indicated below:

REMOVE INSERT

Cover Page Cover Page Technical Manual Deficiency/Evaluation

Report Technical Manual Deficiency/Evaluation

Report Individual Manual Application Sheet Individual Manual Application Sheet Original Equipment Manufacturer (OEM)

Title Page OEM Title Page

Page III Page III Shafting Arrangement, USCG Dwg. No.

905-WMEC-243-001 (FO-1, 2 sheets)

Blade and Palm, USCG Dwg. No.

905-WMEC-245-004 (FO-2, 5 sheets)

Shaft Coupling Assemblies, USCG Dwg.

No. 905-WMEC-243-007 (FO-3, 4 sheets)

Propeller Hub Assembly, USCG Dwg.

No. 905-WMEC-245-003 (FO-4)

Commander

2401 Hawkins Point Road Baltimore, Maryland 21226 Staff Symbol: ESD – Tech Info Mgmt Br Phone: (410 )762-6814 Fax: (410 )762-6898

Coast Guard Amendment No. 6 for Technical Publication 2699

Actuating Unit, USCG Dwg.

No. 905-WMEC-245-008 (FO-5)

CPCH Prop HYD System Diagram, USCG Dwg. Nos. 905-WMEC-245-001 (FO-6, 2 sheets) and 905-WMEC-245- 009 (FO-6, 2 sheets)

Special Tools, USCG Dwg. No.

905-WMEC-245-007 (FO-7)

Appendix J, Relief Valves (entire Appendix)

b. PLEASE NOTE: Distribution for Amendments to Technical Publications has been modified.

Distribution now includes one “paper” copy of Amendment 4 to TP 2699 and a compact disc (CD) with electronic files enclosed. These files include the Amendment as a separate and distinct file and also a Technical Publication file with the Amendment merged. Either may be printed for duplication, as required.

c. Check this publication to ensure that it is complete. Report any discrepancies to this command, with attention to ESD – TIMB. Please provide a brief description of the discrepancy, and recommended remedy, such as marked up pages or copies of new sections to be added. Please continue to submit corrections to this publication as they are identified. Your personal efforts to update technical publications will help to ensure that both maintenance and support personnel remain vigilant in sustaining our engineering systems and equipment.

d. The Surface Forces Logistics Center is very interested in your thoughts regarding this technical information package. If you would please take a few moments, using the link to the Customer Satisfaction Survey below, to let us know your thoughts. Every survey will be reviewed with the intention of making our products and services a valuable resource for your future use:

SFLC Customer Survey and Suggestion Form

M. FRID

By direction

Enclosure: (1) Change pages to TP 2699

CONTROLLABLE PITCH PROPELLER SYSTEM

SWBS 245

270’ WMEC “A” CLASS CUTTERS

Coast Guard Amendment No. 3 for Technical Publication 2699

1. PURPOSE: The purpose of this Amendment is to update Pressure Filter information for the Controllable Pitch

Propeller System.

2. PUBLICATION AFFECTED: Technical Publication 2699

3. INFORMATION: Updating Pressure Filter service information for the Controllable Pitch Propeller System in

Technical Publication 2699, applicable to the 270’ WMEC “A” Class Cutters.

a. Remove and insert pages as indicated below:

Platform Applicability Sheet

SWBS 245-A

Pages D-2 thru D-4, “Series Ordering Information”

Pages D-2 thru D4A, “Service Instructions” and Spare Parts List

b. PLEASE NOTE: Distribution for Amendments to Technical Publications has been modified.

Distribution now includes one “paper” copy of Amendment 3 to TP 2699 and a compact disc (CD) with electronic files enclosed. These files include the Amendment as a separate and distinct file and also a Technical Publication file with the Amendment merged. Either may be printed for duplication, as required.

c. Check this publication to ensure that it is complete. Report any discrepancies to this command, with attention to ESD – Tech Info Mgmt Br. Please provide a brief description of the discrepancy, and recommended remedy, such as marked up pages or copies of new sections to be added. Please continue to submit corrections to this publication as they are identified. Your personal efforts to update technical publications will help to ensure that both maintenance and support personnel remain vigilant in sustaining our engineering systems and equipment.

Commander

2401 Hawkins Point Road Baltimore, Maryland 21226 Staff Symbol: ESD – Tech Info Mgmt Br Phone: (410 )762-6646 Fax: (410 )762-6898

7 March 2013

d. The Surface Forces Logistics Center is very interested in your thoughts regarding this technical information package. If you would please take a few moments, using the link to the Customer Satisfaction Survey below, to let us know your thoughts. Every survey will be reviewed with the intention of making our products and services a valuable resource for your future use:

http://elccentral.uscg.mil/forums/elc/dispatch.cgi/survey/newDocForm/fol/100001/cmd456387057

Enclosure: (1) Change pages to 2699

Distribution: (See page 3)

DISTRIBUTION:

AM # 3 to TP-2699

UNIT COPIES OPFAC

SFLC-MECPL-ENG-SES – NO DISTRIBUTION - 52000

NESU PORTSMOUTH – ANNUAL ONLY (1) 51257

NESU WAT PORTSMOUTH – ANNUAL ONLY (1) 51257

USCGC BEAR (1) 11501

USCGC HARRIET LANE (1) 11503

USCGS NORTHLAND (1) 11504

USCGC TAMPA (1) 11502

ESD MAYPORT (1) 54430

MANUFACTURER’S INSTRUCTION BOOK –

SWBS GROUP(S) 245

270’ “A” CLASS MEDIUM ENDURANCE CUTTER

Coast Guard Amendment No. 2 for Technical Publication 2699 (Amendment Stock # 7610-01-f06-0849)

1. PURPOSE: To update information for the Type 200 Duplex Strainers, applicable to hull 901 thru 904.

2. PUBLICATION AFFECTED: Technical Publication 2699 (TP Stock # 7610-01-P02-8670)

3. INFORMATION: During a Maintenance Effectiveness Program Review on CGC HARRIET LANE, updated information was found to replace information for the Type 200 Duplex Strainers. This information is applicable to all 270’ “A” Class WMEC.

a. Remove old pages and insert new pages as indicated below:

Remove Insert

Platform Applicability Page

SWBS 245A

Individual Manual Application Page, immediately in front of CPP Manual

APPENDIX A

Duplex Series Manual for DD and DC Series Duplex Filters Service Model 200-D # 2308-M-1 and Maintenance Instructions, # 2308 S-M-I

b. Make the appropriate addition to the publication’s record of changes.

c. Place this amendment cover letter in the front of the publication.

d. PLEASE NOTE: Distribution for Amendments to Technical Publications has been modified.

Distribution now includes one “paper” copy of Amendment 2 to TP 2699 and a compact disc (CD) with electronic files enclosed. These files include the Amendment as a separate and distinct file and also a Technical Publication file with the Amendment merged. Either may be printed for duplication, as required.

e. In addition to the Amendment and the Technical Publication found on the CD, new auto-run tutorials with screenshots are provided. These tutorials provide instruction on “How to Print from NE-TIMS” and “How to Install your Technical Documentation on a Shared Drive”. Both are provided in order to answer commonly asked questions. Technical Publication 2699 and Amendment 2 to TP 2699 may also be accessed and printed from NE-TIMS at http://10.38.16.120:1088/NE-Tims/index.html.

f. Check this publication to ensure that it is complete. Report any discrepancies to this command, attention (ELC-05T). Please provide a brief description of the discrepancy, and recommended remedy, such as marked up pages or copies of new sections to be added. Please continue to submit corrections to this

Commanding Officer

Engineering Logistics Center

2401 Hawkins Point Road Baltimore, Maryland 21226 Staff Symbol: (05T) Phone: ( 410 )762-6265 Fax: ( 410 )762-6898

28 March 2006

Amendment 2 to TP 2699 (Continued) publication as they are identified. Your personal efforts to update technical publications help both maintenance and support personnel to do a better job of maintaining our engineering systems and equipment.

Enclosure: (1) Change Pages to TP 2699

Distribution: (See Page 3)

DISTRIBUTION:

Amendment to Technical Publication ACN

Amendment 2 to TP-2699 7610-01-F06-0849

UNIT PROJECT CODE COPIES OPFAC

MLCLANT (vad) (1) (75130)

NESU PORTSMOUTH (1) (51257)

USCGC BEAR (1) (11501)

USCGC TAMPA (1) (11502)

USCGC HARRIET LANE (1) (11503)

USCGC NORTHLAND (1) (11504)

RES TRA CEN (nct) (1) (63100) RES TRA CEN (tew) (1) (63100)

USCG YARD (IND) (1) (31800)

TECHNICAL MANUAL

DEFICIENCY / EVALUATION

REPORT

ANY DEFICIENCIES DETECTED

WITHIN THIS PUBLICATION SHOULD

BE REPORTED BY SUBMITTING A

CG-22 Maintenance/Publication Feedback.

http://sflccentral.uscg.mil/ssf/a/do?

p_name=ss_forum&p_action=1&entryType=8aa6c087485af90c01485b00ef233c71&binderId=130&action=add_folder_entry&vibeonprem_url=1

Maintenance/Publication Feedback (CG-22) Process Guide https://cg.portal.uscg.mil/units/sflc/SFLCDirectivesLibrary/CGTO_PG-85-00-20-G.pdf

IN THE EVENT OF LOSS IN CONNECTIVITY, CALL SFLC-ESD-TIMB (410-582-4725)

https://cg.portal.uscg.mil/units/sflc/SFLCDirectivesLibrary/CGTO_PG-85-00-20-G.pdf https://sflccentral.uscg.mil/ssf/a/do?p_name=ss_forum&p_action=1&entryType=8aa6c087485af90c01485b00da8a3c53&binderId=116&action=add_folder_entry&vibeonprem_url=1

RECORD OF CHANGES

TP NO. 2699

DATE AMEND. NO. NAME SIGNATURE EFFECTIVE DATE

1 10/16/91

3/29/06 2 M. Miltner 3/28/06 3/7/13 3 S. Fischbach 3/7/13 3/31/16 4 D. Rose 3/25/16 2/27/18 5 R. Durham 2/26/18

REVISION

NUMBER DATE SUMMARY OF CHANGES NAME

REV - 01-Jan-2023

This Technical Publication was revised by the Coast Guard to update Appendix D in the following ways: to change part number HH9650-K-16UTSBP to HC9650FRT8Z on page D-1 (PDF page 189), to remove "Ultipor" from page header on page D-2 (PDF page 191), and to remove Buna Seal information from page D-4A (PDF page 194). Pages are identified by a Rev- at the bottom of the page. Tech Pub has been updated to the new revision standard.

K. Priest

DRAWING REFERRAL PAGE

FOLDOUTS TITLE USCG DRAWING NO.

FO-1 SHAFTING ARRANGEMENT 905-WMEC-243-001

FO-2 BLADE AND PALM 905-WMEC-245-004 (5 Sheets) FO-3 SHAFT COUPLING ASSEMBLIES 905-WMEC-243-007 (3 Sheets)

FO-4 PROPELLER HUB ASSEMBLY 905-WMEC-245-003

FO-5 ACTUATOR UNIT 905-WMEC-245-008

FO-6 CPCH PROP HYD SYSTEM DIAGRAM 905-WMEC-245-001 (2 Sheets) &

905-WMEC-245-009

FO-7 SPECIAL TOOLS 905-WMEC-245-007

8-39

REFER TO THE COAST GUARD LOGISTICS INFORMATION

MANAGEMENT SYSTEM – SURFACE TECHNICAL

INFORMATION PORTAL

(CGLIMS-STIP)

TO ENSURE YOU ARE VIEWING THE LATEST REVISION

OF THE CG DRAWING

http://cgweb.netims.uscg.mil:7012/STIP/STIP_EE/login.xhtml#!

TECHNICAL MANUAL

FOR

CONTROLLABLE PITCH

PROPELLER

HULLS

WMEC 270

TBC PURCHASE ORDER

31107

TABLE OF CONTENTS

CHAPTER/PARAGRAPH PAGE

1 GENERAL INFORMATION AND SAFETY PRECAUTIONS

1-1 Introduction 1 - 1 1-2 Safety Precautions 1 - 1 1-3 Equipment Description 1 - 3 1-4 Relationship of Major Units 1 - 3 1-5 CPP Reference Data 1 - 4 1-6 Equipment and Accessories Supplied 1 - 4

2 OPERATION

2-1 Introduction 2 - 1 2-2 CPP Controls and Indicators 2 - 1 2-3 MPCMS Interface 2 - 1

3 FUNCTIONAL DESCRIPTION

3-1 Relationship of Components 3 - 1 3-2 Propeller Hub Assembly 3 - 1 3-3 Propeller Thrust and Intermediate Shafts with Couplings 3 - 2 3-4 Actuating Unit 3 - 3 3-5 Hydraulic System Piping and Component Functions 3 - 5 3-6 Mechanical Pitch-Locking Device 3 - 8 3-7 Hydraulic Pump Drive Assemblies 3 - 9 3-8 Pressure Indicating Gauges 3 - 9

4 SCHEDULED MINTENANCE

4-1 Introduction 4 - 1 4-2 General Maintenance Precautions 4 - 1 4-3 Scheduled Shipboard Maintenance 4 - 2 4-4 Daily Preventive Maintenance Action 4 - 2 4-5 Monthly Preventive Maintenance Action 4 - 4 4-6 Quarterly Preventive Maintenance Action 4 - 4 4-7 Six Month Maintenance Requirements Action 4 - 5 4-8 Annual Preventive Maintenance Action 4 - 6 4-9 Maintenance Action Requiring Drydock 4 -10 4-10 Four Year Maintenance Requirements

{Drydock Required) 4 -11

5 TROUBLESHOOTING

5-1 General 5 - 1 5-2 Types of Malfunctions 5 - 1 5-3 Troubleshooting Guide 5 - 2

6 CORRECTIVE MAINTENANCE

6-1 Introduction 6 - 1 6-2 Impact Damage 6 - 1 6-3 Removal of Damaged Components for Repair 6 - 1 6-4 Blade Repair 6 - l_ .· 6-5 Hub Repair 6 - 7 .. -·. · 6-6 Shaft Corrective Maintenance 6 - 7.;

I

TABLE OF CONTENTS

(Continued)

CHAPTER/PARAGRAPH

PARTS LIST

7-1 Introduction 7-2 List of Major Components 7-3 Parts List

REMOVAL/INSTALLATION

8-1 Introduction 8-2 Actuating Unit 8-3 Propeller Blades 8-4 Thrust Shaft 8-5 Propeller Shaft and Hub 8-6 Intermediate Shaft

II

PAGE

7 - 1 7 - 1 7 - 1

8 - 1 8 - 1 8 -14 8 -16 8 -24 8 -34

LIST OF TABLES

TABLE TITLE PAGE

1-1 CPP Reference Data 1 - 5 1-2 Equipment and Accessories Supplied 1 - 6 5-1 Detailed Troubleshooting Guide 5 - 3 6-1 Recommended Welding Process 6 - 4 6-2 Recommended Straightening Procedure 6 - 5 6-3 Propeller Hub Clearance 6 - 9 7-1 Major Components 7 - 2 8-1 Installation Equipment 8 - 2

FOLDOUT REFERRAL

FOLDOUTS TITLE USCG DRAWING NO.

*FO-1 Shafting Arrangement 905-WMEC-243-001 (2 Sheets) *FO-2 Blade and Palm 905-WMEC-245-004 (8 Sheets) *FO-3 Shaft Coupling Assemblies 905-WMEC-243-007 (4 Sheets) *FO-4 Propeller Hub Assembly 905-WMEC-245-003 *FO-5 Actuator Unit 905-WMEC-245-008 *FO-6 CPCH PROP HYD System Diagram 905-WMEC-245-001 (2 Sheets) and

905-WMEC-245-009 (2 Sheets) *FO-7 Special Tools 905-WMEC-245-007

*REFER TO COAST GUARD LOGISTIC INFORMATION MANAGEMENT SYSTEM –

SURFACE TECHNICAL INFORMATION PORTAL (CGLIMS-STIP) TO ENSURE YOU

ARE VIEWING THE LATEST REVISION

CGLIMS-STIP

APPENDICES

A Suction Filter/Strainer B Main Hydraulic Pumps C Head Tank Pump D Pressure Filter Manifold E Hydraulic Control Manifold F Heat Exchanger G Sump Heater H Sight Flow Indicators I Temperature Control Valve J Relief Valves

III

http://cgweb.netims.uscg.mil:7012/STIP/STIP_EE/#!

CHAPTER 1

GENERAL INFORMATION AND SAFETY PRECAUTIONS

1-1. INTRODUCTION

This manual covers the operation, functional description, maintenance, troubleshooting, parts listing, and installation for the Escher Wyss controllable-pitch propeller. F0-1 shows the arrangement of the main components of one shaft line of the twin screw propeller system. F0-6 shows the hydraulic piping diagram.

1-2. SAFETY PRECAUTIONS

safety precautions necessary for the protection of These are recommended precautions that personnel during all phases of operation and maintenance.

A. ALL MANUALLY OPERATED CPP VALVES SHALL BE LOCKED IN THE

NORMAL OPERATING POSITION iaw 901 WMEC 505-001

B. EMERGENCY ENGAGEMENT OF PITCH-LOCKING DEVICE

1. The propeller shaft and the ship must be stationary.

2. Hydraulic pumps must be shut down .

3. The shutoff valve in the discharge line downstream of the pump check valves must be closed.

C. GENERAL MAINTENANCE PRECAUTIONS

1. During maintenance or repair work on actuating unit or propeller shafting, the ship, propeller shaft, and hydraulic pumps must be shut down . .

2. Extreme cleanliness must be observed during work on all hydraulic equipment. Impurities in the hydraulic oil or equipment can affect operation, or damage equipment.

3. When maintenance or repair becomes necessary for any component of the hydraulic system, the component should be isolated from the system and any residual hydraulic pressure must be bled off.

CAUTION

Keep hydraulic system purged of air. Air in the oil can cause loss of precise pitch-control and greatly reduces component life.

1-1

53-00/0la 7-22-83

CAUTION

To prevent damage to hydraulic oil cooler inner tubes, do not use metallic bristle brushes when cleaning.

CAUTION

Even small dents, nicks or scratches on leading edges of propeller blades can cause cavitation hazard. Insure there are no damaged blade areas •.

CAUTION

When draining sump tanks for cleaning operations, monitor oil level to prevent dry-running of pumps.

CAUTION

When removing propeller hub assembly from propeller shaft, ensure hub is properly supported with chain hoist and slings.

CAUTION

During disassembly of propeller hub assembly, use extra caution not to damage piston or piston slide rings during removal.

CAUTION

When refitting propeller blades to the hub assembly, special care must be taken to prevent damage to blade surface, blade palm, blade trunnion and blade seal surface area.

CAUTION

When repairing propeller blades by welding buildup, avoid welding in the blade root area (10 inches outward from the blade root radius) •

1-2

CAUTION

When installing shafting, ensure the 12 bolt holes and bolt heads are number matched at each coupling point.

1-3. EQUIPMENT DESCRIPTION

A. BLADE PITCH CHANGES

B.

The twin propeller system includes an arrangement of hub-mounted controllable-pitch blades. The system permits varying degrees of propeller blade pitch while monitoring constant engine RPM until the engine is producing optimum power at idle speed, at which time the engine speed and propeller blade pitch are increased together to maintain n:iaximum efficiency of the engine and drive train. The propeller blades may be pitched in either the ahead or astern position as desired.

PROPELLER CONTROL AND PITCH INDICATION

Comnand signals are sent by remote control from the pilot house or from the ECC (Engineering Control Center) console to the electronic pitch-setter mounted on the actuating unit. In response to a signal received by the pitch-setter, the propeller pitch is changed to a set position' by electrical and mechanical means. An electrical actual-pitch transmitter on the actuating unit transmits the actual blade pitch to indicators on the bridge and on the ECC consoles.

1-4. RELATIONSHIP OF MAJOR UNITS

The controllable-pitch propeller (CPP) installation includes two inboard-rotating controllable-pitch propeller systems. Each system has four removable propeller blades mounted on a hub assembly. Each hub assembly is connected by a hollow-bored shaft line to the main reduction gear. An actuating unit mounted on the forward end of each reduction gear directs oi 1, under pressure, through either of two oi 1 tubes in the hollow shaft line. Depending on whether the control signal is for ahead or astern pitch change, the oil is directed through the tubes to either side of the servomotor piston in the prope 11 er hub. The forward or aft movement of the servomotor piston will then change the propeller pitch. There are four hydraulic pumps in each CPP system. Three of the pumps are driven by electric motors located in the vicinity of the reduction gears. The remaining pump is driven by the reduction gear. F0-1 shows the arrangement of the major components of one shaft line of the twin screw system. F0-6 shows th!

53-00/0la

1-3 hydraulic piping for the starboard propeller system. Except for location of hydraulic system components t port and starboard systems are identical.

1-5. CPP REFERENCE DATA

CPP equipment and their specifictions are listed in Table 1-1.

1-6 EQUIPMENT AND ACCESSORIES SUPPLIED

Equipment and accessories supplied for the CPP system are listed in Table 1-2 •

53-00/0la

1-4

TABLE 1-1 CPP REFERENCE DATA

EQUIPMENT

Propulsion Diesels Manufacturer:

Model:

Speed:

(2 per ship, 1 per shaft)

ALCO

B-251-F

1025 RPM

Power:

Reduction Gear Box (2 per ship, 1 Manufacturer:

Model:

Design Maximum Input Speed:

Design Maximum Input Power:

Reduction Ratio:

Propeller Assembly (2 per ship) Manufacturer:

53-00/0la 7-22-83

Model:

Maximum Speed:

Pounds Thrust Per Propeller:

Design Ahead:

3650 Horsepower per shaft) English Electric Corporation R42H 1,025 3650 Horsepower 3.94:1

Tacoma Boatbuilding Co.

260 RPM

40,350

10.150 ft@ the .700 radius

1-5

Qty Per Ship Item Name

4 Propeller Blade Starboard

4 Propeller Blade Port

2 Hub Assembly, RH and LH

2 Propeller Shaft

2 Intermediate Shaft

2 Thrust Shaft

2 Actuating Unit

2 Thrust Bearing

1 Oil Injector

1 Pump Set

53-00/0la 7-22-83

TABLE 1-2

EQUIPMENT AND ACCESSORIES

SUPPLIED, CPP SYSTEM

Approx Drawing Weight No. or in Pounds Model Overall Dimensions {Each}

EW No. 8 4@ 61.6" X 29" X 4" 625 350 255 (Propeller

Assy = 8,650)

EW No. 8 4@ 61.6" X 29" X 4" 625 350 254 (Propeller

Assy = 8,650)

8-349-950 33.4"(dia.) X 42.8" 6,150

MD-850

901-WMEC-243-004 10.55"(dia) X 54'0" 15,700

901-WMEC-243-004 8.92"(dia) X i6'1.2" 2,535

901-WMEC-243-004 9"(�ia) X 8 1 8.8" 1,600

901-WMEC-245-008 2l"(dia) X 25" 535

901-WMEC-244-001 1,527

SKF 226400

SKF 729122

1-6

2-1. INTRODUCTION

CHAPTER 2

OPERATION

The controllable-pitch twin propeller system is controlled from either the Pilot House or the Engineering Control Center (ECC). Each propeller hydraulic system receives its oil pressure from one of its three hydraulic pumps. Under normal conditions, only one pump (that driven by the reduction gear) need be in operation. Pressurized oil from the pump is piped to the actuating units for each propeller. When a pitch change signal is received from the Pilot House or ECC, the actuating unit selects directional flow through either of two oil tubes in the hollow bore of the shaft. Pressurized oil will then be directed to either side of the servopiston located in the hub assembly and increase or decrease the pitch of the blades as required.

2-2. CPP CONTROLS AND INDICATORS

Normally, propeller pitch changes and propulsion diesel engine RPM are controlled remotely from the Pilot House or from ECC. Monitoring of the CPP system is performed at the ECC operating console and Local Operating Stations (LOS) 5 and 6. If remote control of pitch change fails, manual control by Morse Cable from the ECCC is available; failing that, local manual control from the electrical-mechanical actuator adjacent to the o.o .

box may be employed. Should all the fore�oing methods of pitch control fail, the propeller blades can be mechanically fixed in the "Design Ahead" position enabling the vessel to continue until repairs can be effected.

Blade pitch is locked in a set position at the aft flange of the thrust shafts in Refrigerated Dry Stores, 4-169-0-A. Refer to paragraph 2-3C for emergency manual pitch-lock procedures.

Alarm and indicating devices for the complete CPP system are located at Local operating Stations or at equipment locations in the engine room.

Alarm devices for low oil pressures, low oil levels and high oil temperatures are also activated at the main control console in ECC.

2-3 MCPMS INTERFACE (SEE TANO MPMCS DOCLKNTS FOR A DETAILED DESCRIPTION)

An adjustment of ship speed at any point in the full engine and shaft speed range is possible by changing propeller pitch. To provide economic and effective operation of the ship, a combination function is provided.

The controlling station's throttle lever position signal will be input to the pitch function generator to produce an adjustable, progranmed pitch signal. The function generator will be calibrated so that the pitc� position will be acceptable at the particular demanded engine speed. _- Jhe pitch signal will be input to a slew rate controller so that the pitch

53-00/0lb

2-1 demand to the pitch actuator will change at an acceptable rate, independent of the speed at which the operator moves the throttle lever.

The slew rate controller will control the normal increasing and decreasing pitch rate in the ahead or astern direction. This normal rate will be in effect when the lever is in either the ahead or astern position. There is a separate provision to decrease pitch more rapidly in the cases where the pitch position is ahead and the lever is moved to astern or the pitch posi tion is astern and the lever is moved to ahead. If the pitch position is ahead and the lever is rapidly moved to an astern position the pitch will decrease to neutral at the fast rate and then increase in the astern direc tion at the normal rate. For the extreme case of a crash astern manuever, a third rate is provided. This rate will be in effect when the lever is moved full astern.

The pitch demand voltage from the slew rate controller controls the pitch actuator. The pitch actuator maintains the pitch at the demanded position.

In the event that the signal from the control electronics is disconnected from the actuator (Speed/Pitch Emergency Manual or Vital Alarms) the actua tor will cause the pitch to move to its neutral position. In the Speed/ Pitch Emergency Manual mode the pitch may be controlled by a mechanically linked Manual Pitch Lever.

A.

53-00/0lb 7-22.:.s3

SPEED/PITCH MODE SELECTION

Speed/pitch control has three modes of operation: ECC Automatic, Pilothouse Automatic and Emergency Manual. A three-position selector switch at the ECC will ;,select the mode of operation, only one of which can be in effect at any given time.

1. ECC Mode

Transfer of control to the ECC automatic mode is accom plished by placing the Speed/Pitch mode switch in the ECC position. Transfer will not be allowed if the manual speed lever is not at its neutral position. Indicating lights at the ECC and Bridge Console will illuminate, indicating that ECC has control.

2. Pilothouse Mode

Transfer of control to the Pilothouse is accomplished by p 1 acing the mode switch in the PL THS position. Transfer will be allowed provided both the ECC and Bridge Console (BC) throttle levers are in the STOP position and the manual speed lever is at Neutral. Indicating lights at the ECC and BC will illuminate, indicating Pilothouse has control •

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3. Emergency Manual Mode

The Emergency Manual mode may be selected at any time by placing the mode switch in Emergency Manual. In this mode the pitch signals from the electronics will be disconnected so that the pitch may be positioned by the manual lever con nected to the pitch mechanisms. An indicating light at the ECC will illuminate, indicating the operating mode is in Emergency Manual. At the BC, the ECC control indicating light will be illuminated.

a. Manual Control

Manual control of propeller pitch is accomplished through a mechanical transfer mechanism located between the pitch actuator and the conmand input shaft on the Escher Wyss oil distribution unit. The transfer mechanism wi-11 be operated, via push-pull cable, by a control mounted on the ECCC next to the manual pitch control lever. When this control is operated, a steel key will shift in the transfer mechanism disengaging the pitch actuator and engaging the mechanical pitch control. The actual transfer will not occur until the mechanical pitch control is moved to a position that matches the pitch commanded by the pitch actuator.

4. Pitch Failures

The pitch failures described below will result in a Pitch Control Failure in the Speed/Pitch automatic (either ECC or Pilothouse) mode. This will cause an automatic shift to Emergency Manual mode.

a. Pitch Position Fail

An excessive error is found when the actual pitch posi tion is compared to the demand signal from the s 1 ew rate controller.

b. Pitch limit Error c.

The actual pitch position and the demand signal will be monitored to prevent the pitch travelling beyond speci fied limits or the demand output exceeding the limits.

This error will result in a Pitch Control Failure.

Wrong Pitch Directi�n

The actual pitch position signal will be differentiated in order to determine the direction in which the p-ttch angle is changing. If the pitch travel is not i�"th� correct direction a Pitch Failure will result.

2-3

5.

d. Neutral Pitch Error

Setpoints will detect neutral pitch position. If the controlling throttle lever is at stop, or the system is forced into the Speed/Pitch Emergency Manual mode and after a short time delay the pitch is not at its neutral position {or travelling toward neutral) a Pitch Control Failure will result. This error will result in power to the actuator being removed, which prevents an actuator failure from increasing pitch while the system is in Emergency Manual or the lever is at stop. When the system is placed back in the automatic mode power will be restored to the actuator.

e. Actuator Failure

Following any system failure the demand output from the control system to the actuator wil be disconnected causing the actuator to move the pitch to neutral. If, after a short time delay, the pitch does not move toward neutral, the power will be removed from the actuator.

Neutral Pitch Demand

The following conditions will �lectronically disconnect the pitch actuator causing the p.'iu:h to travel to its neutral position:

a. Speed/Pitch Emergency Manual

b. Reduction Gear L.O. Press Low/Low Vital Alarm

c. Clutch Air Press Low/Low Vital Alarm

d. Engine L.O. Press Low/Low Vital Alarm

B. NORMAL START-UP

53-00/0lb 7-22-83

Before propulsion engine start-up, the following steps must be taken to ready the controllable-pitch propeller system.

1. Insure electrical power is avai 1 able to operate TANO controls and for hydraulic pump motors (for pumps B, C).

2. Verify proper valve alignment of the CPP Hydraulic System (Refer F0-6) •

2-4

CAUTION

Do not alter relief valve settings prior to CPP hydraulic system startup.

3. Position motor contra 11 er for Pump B into the "ON" mode and motor controller for Pump C in the 1

1AUTO" mode. Both pumps should start. Verify headtank make-up pump motor controller is in 11AUT0 11 model.

4. Monitor CPP Hydraulic System pressures and temperatures for proper readings (See paragraphs 3-5 and 3-8). Monitor pres sure filter differential pressure gauge for filter condition. Change filter if necessary. (Important: Check suction strainer visual indicator for strainer condition.)

5. Perform functiona-1 check pitching blades from design ahead to astern, and back (20 seconds each direction) at all control stations.

6. Move command lever to zero-thrust position before propulsion engine start-up.

7. CPP Hydraulic System is now in the in-port manuevering attitude. Steady state steamin� attitude involves position ing Pump B motor controller: .in the 11AUT0 11 position and Pump C motor controller in the 1

10FF 11 position.

C. EMERGENCY OPERATION

53-00/0lb 7-22-83

Four possible emergency situations, or combinations thereof, could occur.

1. Failure of hydraulic pump driven by the reduction gear.

(Pump A)

Use the electric motor driven hydraulic pumps to maintain system pressure. (Pumps B & C)

2. Failure of one (or both) electric motor driven hydraulic pumps. (Pumps B & C)

3.

Use the hydraulic pump driven by the reduction gear to main tain system pressure. (Pump A)

Failure of both the electric motor driven hydraulic pumps and the reduction gear driven hydraulic pumps. (Pumps A, � & C)

Install locking pins in the after coupling flange ot' the thrust shaft.

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8-4-83

a. Bring vessel and propeller shafts to a complete stop, disengage reduction gear clutch and secure diesel engine(s).

b. Engage the turning gear on the reduction gear assembly for the affected shaft and rotate the shaft until one of the four screw plugs (item No. 16, F0-3) on the after coupling flange of the thrust shaft is in the desired position for removal.

c. Stop the head tank make-up pump.

d. Open PHS-10 and shut PHS-9.

e. Start the head tank make-up pump and pitch the blades to 11DESIGN AHEAD".

f. Stop the head tank make-up pump.

g. Open PHS-9, shut PHS-10.

h. Shut PHS-8 (isolate system from head tank).

i. Open PHS-5 to bleed off static head pressure on system.

Shut PHS-5.

j. Carefully begin removing the screw plug from the coup ling flange. If there appears to be any residual pressure in the system, ,'replace screw plug and bleed off system again before proceeding any further. Remove screw plug.

k. Insert first locking pin (item No. 15, F0-3) into place with its flat side parallel to the flange face. If necessary, reposition the oil tube with the head tank pump as required. A rubber faced mallet may be used to tap the pin into position.

CAUTION

Do not force pin into position.

Rotating the pin slightly may help. A Ml2xl.75 bolt inserted into the threaded hole in the pin's end will facilitate pin rotation.

l. With the first locking pin fully inserted, replace the screw-plug renewing the "0-ring" if necessary •

2-6 m.

n.

o.

p.

q.

r.

s.

t.

u.

Install the remaining three locking pins in the same manner, rotating the shaft as necessary •

Open PHS-8.

Disconnect linkage between PHS-1, PHS-4 and PHS-7.

Open PHS-4, check PHS-1 open and PHS-7 shut.

Check hydrau 1 i c system lined up as shown on F0-6 (with the exception of PHS-4).

Disengage turning gear on affected reduction gear assembly.

Start head tank make-up pump.

Start main propulsion engines.

Engage reduction gear clutch on the shaft with the locking pins installed only when ahead way on the ship is desired.

v. The other propulsion shaft is operated in its normal mode.

Monitor oil level in head tank • Fi 11 by hand if,. ,, necessary.

Reduce engine RPM as required to keep oil temperature below 1450.

2-3.C.4 DISENGAGING PITCH-LOCKING PINS

After effecting hydraulic system repairs, remove the pitch-locking pins as follows:

53-00/0lb 8-4-83

a. Bring vessel and propeller shafts to a complete stop.

b. Disengage reduction gear clutch and secure main diesel engine.

c. With the turning gear, rotate shaft until one of the four screw-plugs is accessible. (Screw-plugs are located on the aft thrust shaft flange).

d. Shut valve PHS-8 {F0-6) to isolate shaft head-tank pressure •

2-7

f. Open PHS-5 to relieve remaining pressure on shaft.

Shut PHS-5.

g. Only after the shaft has definitely been de-pressured, remove the first screw-plug.

h. Install a slide hanmer in the end (Ml2xl.75) of the exposed locking pin.

i. Extract pin.

NOTE: If the pin cannot be removed, jar pin at eyebolt area and attempt extraction again. If the pin still will not move, move the oil tubes fore or aft slightly with the head tank make-up pump. See paragraph 2-3.C •• 3

j. Once the pin is removed, restore the screw-plug and 110-ring 11

k. Rotate the shaft to each of the three remaining pin positions and follow the above routine.

1 • Connect linkage between ,PHS-1, PHS-4 and PHS-7 and open

PHS-1.

m. Open valve PHS-8, check CPP Hydraulic System for proper alignment and start pump, B or c.

n. Disengage turning gear and start main diesel engine.

o. Put CPP control on normal operation position and engage reduction gear clutch.

p. The vessel may resume underway operation.

5. Failure of the Ship's Control System

Use any hydraulic pumps available and the emergency control cables provided to pitch the blades in the desired position •

2-8

CHAPTER 3

FUNCTIONAL DESCRIPTION

3-1. RELATIONSHIP OF CPP COMPONENTS

The propeller installation consists of two inboard-rotating controllable pitch propellers. Each propeller system includes: four blades mounted on a 33.4-inch diameter hub assembly; double oil tubes extending through the hollow-bore shafts; an actuating unit; hydraulic pumps and a GEC reduction gear. Each prope 11 er hydrau 1 i c system has the necessary hydrau 1 i c contra 1 valves, hydraulic system accessories and components to automatically or manually control and monitor propeller blade pitch in a range from full ahead to full astern.

3-2. PROPELLER HUB ASSEMBLY (F0-4)

The hub, which holds the four propeller blades, .is bolted to the aft flange of the propeller shaft. Around the edge and between the aft flange of the hub and the propeller shaft, six dowels are provided to transmit the torque from the propeller shaft to the hub and blade assembly. Major components of the hub assembly and their functions are described in the following paragraphs

A. SERVOMOTOR PISTON

The piston ( 7) is secured to the aft end of the actuating rod {15) by the actuating rod nut (4) and locking screw (5).

Pressurized oil moves the servomotor piston fore and aft within the propeller hub cap (1), which then acts as a servomotor cylinder. The propeller cap, which is bolted to the hub, forms the aft end of the propeller hub assembly. Four guide rods (30), supported in a guide flange (36), guide the piston assembly move ment. When the servomotor piston moves through its full stroke, the propeller blades change pitch from full ahead to full astern or vice versa.

8. ACTUATING ROD

The actuating rod (15), which is attached to the servomotor piston, contains the hub oil tube {57). Pressurized control oil goes through the hub oi 1 tube into the aft servomotor space to move the servomotor piston in the ahead position. In the annular space between the actuating rod and the hub oil tube, oil runs to the hub cavity - the forward servomotor space. This oil pressure moves the servomotor piston to the astern position.

C. LINKS AND CRANK RINGS

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Four links with ball and socket joints (19 and 20) and eight.}ins (58 and 63), connect the actuating rod with the servomotor piston

3-1

D.

to four crank rings (52 and 53). The crank rin9s are mounted to the four blade trunnions by trunnion nuts (49). When oil pressure moves the servo piston fore or aft, rotary movement of the crank rings is transmitted to each of the trunnions and blades by means of two fitting pins (SO).

BLADE TRUNNIONS

Each blade trunnion (46 and 47) is supported by two bearings in the propeller hub body. One bearing is a blade trunnion bushing

(48) and the other is a collar bushing (51). Centrifugal forces of the prope 11 er blades are carried to the prope 11 er hub by the blade trunnion nuts (49), the crank rings (52 and 53), and the collars of the outer bushings.

E. HUB ASSEMBLY SEALING, VENTING AND DRAINING

The circular space between the actuating rod and the hub body, the forward space between the hub body and the aft flange of the propeller shaft, and the bore in the blade trunnion are all connected to the head tank. A space between the blade seals and the hub is also connected to the head tank. Head tank connections are made to the actuating unit and shafting.

1. Sea 1 i ng. The above arrangement re 1 i eves the b 1 ade sea 1 s from pressure in the astern pressure chamber of the hub cavity. When the ship is at r;-est the pressure in the seal space is always higher than 'the surrounding water pressure because the head tank is above the water 1 i ne. When the ship is underway, seal pressure is raised to meet the increased water pressure on the blade seals. Besides the blade seals, there are static 0-ring seals which prevent the intake of seawater and the loss of system hydraulic oil.

2. Screw Plugs. Four screw plugs (3) permit the hub servomotor spaces to be vented and drained.

3. Outer Shaft Hood. The ho 11 ow space between the aft flange of the propeller shaft and the outer shaft hood is filled with tallow.

3-3. PROPELLER, THRUST AND INTEIUEDIATE SHAFTS WITH COUPLINGS (F0-1)

The propeller, thrust and intermediate shafts are connected by flanged coup 1 i ngs. The shafts are ho 11 ow-bored to ho 1 d the doub 1 e oi 1 tubes that extend from the actuating unit to the hub assembly. The shaft assembly transmits the propulsion engine torque via the reduction gear to the propeller hub with the double oil tubes rotating with the shafts. At th� propeller hub, both tubes are connected to the forward end of the- .. �uts actuating rod. The actuating rod is rigidly connected to the servomotor

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3-2 piston providing a mechanical connection between the hub servomotor piston and the actuating unit mounted on the main reduction gear.

3-4. ACTUATING UNIT (F0-5)

The actuating unit housing is bolted to the forward face of the reduction gearbox. The control shaft (4) is mounted on the forward face of the gear shaft. The purpose of the actuating unit control shaft is to distribute the ahead and astern oil to the propeller hub. Movement of the servomotor piston changes propeller blade pitch. When a command signal is given, the actuating unit acts as a proportional amplifier allowing a precise setting of the propeller pitch by controlling movement of the servomotor piston with pressure oil.

NOTE: -The linkage clamp and command shaft should be secured with a taper pin to prevent the clamp from rotating around the control shaft, causing loss of pitch control. Drawings 901 WMEC 252-013 and 245-008 have been revised to reflect installation of the taper pin.

A. INTERNAL DESCRIPTION OF ACTUATING UNIT

The oil-filled casing of the actuating unit is sealed against the rotating control shaft by the sealing ring (58) and two oil retainer rings (60) in the seal cage. During operation, the sealing ring (58) allows the forward oil retainer ring (60) to be relieved of pressure through actuating connection D. The sealing ring (58), in effect, seals against the housing pressure. With the unit at standstill, connection Dis automatically closed, and the oil retainer ring (60) is then under head-tank pressure.

The aft oil retainer ring (60) prevents gearbox oil from entering.the system. Connection Hallows inspection of the seal condition. The non-revolving oil feed bushing

(54) is on the forward section of the control shaft (4).

Two retainer bushings (38), threaded into the oil feed bushing, secure its axial position. At the same time, the two retainer bushings provide a control-oil connection between the actuator valve assembly and the oil feed bushing.

B. ACTUATING UNIT VALVE ASSEMBLY

The complete valve housing assembly is mounted on the actuating unit housing. The valve housing contains the control bushing (14) with control piston (19) and pilot piston (17). The pilot piston is connected to the valve link (63) by a threaded rod (33). The valve link is moved by the command lever (34) and the feedback lever (81).

C. PITCH CHANGE WITHIN THE ACTUATING UNIT

To make a pitch change to the ahead direction, the command input shaft is rotated by a command signal from the remote control system. The movement of the command lever (34) changes the position of the valve link (63). The valve link pivots in the bearing (80) of the feedback lever (81).

The feedback lever is linked to the servopiston in the propeller hub through its

3-3

53-00/0lc connection to the oil tubes. At this point, the feedback lever is still stationary as no pitch change has as yet been effected.

Initial movement of the valve link (63) displaces the pilot piston (17) to the right or ahead position while the control piston (19) remains stationary. Oil pressure acting on the small area of the control piston is then allowed to flow to the large area of the control piston. The oil pressure now moves the control piston until the temporary port pressure of the pilot piston acting against the control piston is closed again. Thus, the control piston follows the movement of the pilot piston.

1. Follow-Up. The change of pitch at the hub assembly moves the oil tubes, and with them, the feedback lever (81) in the actuating unit. This, in turn, resets the valve link (63), which pivots around collar pin (25) to the position set by the convnand lever (34). The resetting motion of the valve link is transmitted to the pilot piston (17) and control piston (19) until the open control edges are closed again.

The oil flow through the ahead duct is now stopped, movement of the servo system is comp 1 eted, and the new prope 11 er blade pitch is set.

2. Ahead Pitch Change Cycle. The ahead displacement of the control piston causes the control edge at the supply pressure chamber downstream of actuating unit connection B to open. Pressurized supply, ofl then flows into the ahead duct and into the inner oil ,tube so that the servomotor piston in the propeller hub will move forward.