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Folks,

Dummy Log Speed Transmitter and Dummy Log Distance Transmitter, I.C. Instruction Book No. 703, 1944, documents the dummy log. The dummy log was used to provide the speed and distance information use by navigation and fire control instruments aboard ship when the pit sword log was not available (i.e. shallow water or damaged.)

In this online version of the manual we have attempted to keep the flavor of the original layout while taking advantage of the Web's universal accessibility. Different browsers and fonts will cause the text to move, but the text will remain roughly where it is in the original manual. In addition to errors we have attempted to preserve from the original, this text was captured by a combination of optical character recognition and human typist. Each method creates errors that are compounded while encoding for the Web. Please report any typos, or particularly annoying layout issues to the Mail Feedback Form for correction.

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RESTRICTED
DUMMY LOG SPEED TRANSMITTER
AND
DUMMY LOG DISTANCE TRANSMITTER
I. C. INSTRUCTION BOOK NO. 703
MANUFACTURED FOR THE BUREAU OF SHIPS OF THE U. S. NAVY DEPARTMENT
BY
FRIEZ INSTRUMENT DIVISION BENDIX AVIATION CORPORATION
BALTIMORE MARYLAND
FRIEZ I.B. #87
August, 1944
CONTRACT NOS.  DATE
NOBs 12433 Jan. 4, 1944
NOBs 13011 Feb. 12, 1944
NOBs 16601 Sept. 4, 1944
NOBs 16473 Sept. 4, 1944



ERRATA SHEET
FOR
I.C. INSTRUCTION BOOK NO. 703

Drawing V-40255 - Sheet 2 - Page IV

Under notes - note one: Change "two coats of gray alkyd resin base paint" to "one coat of gray alkyd resin base paint".

Drawing V-40256 - Sheet 1 - Page V

Terminal Marker Plate (39) at upper left of illustration, circuit designations from top to bottom should read Y, YY, Y1, Y2, Y3.

Same drawing in reference to: reversible motor (15). A thrust screw (59) with lock nut (148), not shown, has been added at the right end of this motor to control the thrust of the shaft.

Drawing V-40256 - Sheet 2 - Page VI

The thrust screw (59) and lock nut (148) mentioned above appear incorrectly in the upper right hand view. This screw, square headed and slotted, will be behind the center of the three terminals of the suppressor and will not be visible in this view.

Drawing V-40256 - Sheet 3 - Page VII

Item 59 should read: Screw, thrust, 1 req'd., brass, 5-40 thd., Drawing #501816

Item 148 should read: Nut, 1 req'd., brass, 5-40 thd., Drawing #500735-14

Same drawing - note 1: Change "two coats of gray alkyd resin base paint" to "one coat of gray alkyd resin base paint".



RESTRICTED

This instruction book is furnished for the information of commissioned, warranted, enlisted and civil personnel of the Navy, whose duties involve design, instruction, operation, and installation of inter-communication equipment. The word "restricted" as applied to this instruction book signifies that this instruction book is to be read only by the above personnel and that the contents of it should not be made known to persons not connected with the Navy.



GUARANTEE

The contractor guarantees that the equipment will perform the duties specified during the one-year period of operation following installation. In case the equipment fails to meet the specifications for performance during this period and the failure is not promptly rectified by the contractor at his expense, the equipment will be returned to the contractor and the contract price shall be refunded to the Government. The transportation charges for the return of the instrument to the works of the contractor shall be at his expense.

FRIEZ INSTRUMENT DIVISION
BENDIX AVIATION CORPORATION

It is suggested that a thorough study of the instructions be made before attempting to install and use the equipment.



TABLE OF CONTENTS

Page No.
I. DESCRIPTION OF THE INSTRUMENTS
1. GENERAL 1
1-1 Dummy Log Speed Transmitter 1
1-2 Dummy Log Distance Transmitter 1
2. DUMMY LOG SPEED TRANSMITTER (DRAWINGS V-40255 & BW-00223) 1
2-1 The Transmitter Assembly 1
2-2 Speed Transmitter Dials 2
2-3 Speed Transmitter Case 3
2-4 Spare Parts 4
3. DUMMY LOG DISTANCE TRANSMITTER (DRAWINGS V-40256 & BW-00224) 4
3-1 The Receiving Unit 4
3-2 The Reversible Motor Unit 4
3-3 The Synchronous Motor Disc and Roller Mechanism 5
  3-3-1 Micro-Switches 5
3-4 The Transmitter Generator Drive Mechanism and Generator 6
3-5 Internal Wiring 6
3-6 The Dummy Log Distance Transmitter Case 7
3-7 Spare Parts 7
II. THEORY OF OPERATION
1. DUMMY LOG SPEED TRANSMITTER (DRAWINGS V-40255 & BW-00223) 8
2. DUMMY LOG DISTANCE TRANSMITTER (DRAWINGS V-40256 & BW-00224) 8
2-1 The Receiving Motor Unit 9
2-2 The Reversible Motor Unit 9
2-3 The Synchronous Motor, Disc and Roller Mechanism 10
  2-3-1 Micro-Switches 11
2-4 The Distance Transmitter Generator Drive Mechanism and Generator 11
  2-4-1 The Differential 12
  2-4-2 The Follow-Up Motor and Rheostat 12
  2-4-3 The Transmitter Generator 12
3. SECURING AND STARTING THE DUMMY LOG SYSTEM 12
III. INSTALLATION
1. GENERAL 14
2. DUMMY LOG SPEED TRANSMITTER (DRAWING V-40255) & XS-46426 14
3. DUMMY LOG DISTANCE TRANSMITTER (DRAWING V-40256) & XS-46426 14



 
Page No.
IV. MAINTENANCE
1. GENERAL-COMPLETE SYSTEM 16
2. TYPE OF LUBRICANT TO BE USED FOR LUBRICATION 17
3. DUMMY LOG SPEED TRANSMITTER (DRAWING V-40255) 17
4. DUMMY LOG DISTANCE TRANSMITTER (DRAWING V-40256) 18
5. REPLACING GEARS AND SHAFTS CONTAINING SCREW PINS 19
V. TESTING AND ADJUSTING
1. GENERAL 20
2. DUMMY LOG SPEED TRANSMITTER (DRAWING V-40255) 20
3. DUMMY LOG DISTANCE TRANSMITTER (DRAWING V-40256) 21
3-1 The Receiving Motor 21
3-2 Setting Stop Switches 22
3-3 Adjusting Cam and Brush Ring Assembly 22
3-4 The Reversible Motor Unit 22
3-5 The Synchronous Motor and Carriage 22
3-6 The Differential, Follow-Up Motor and Rheostat 23
3-7 The Distance Transmitter Generator 23
VI. SELF-SYNCHRONOUS GENERATORS AND MOTORS
1. GENERAL DESCRIPTION 24
2. THEORY OF OPERATION 24
3. MAINTENANCE 25
4. DISASSEMBLY 25
5. SETTING THE SELF-SYNCHRONOUS GENERATOR OR MOTOR TO ELECTRICAL ZERO 26

LIST OF DRAWINGS

Mfgr's. Drawing No. Title Page No.
BW-00223 Dummy Log Speed Transmitter
Exploded Isometric View
I
BW-00224 Dummy Log Distance Transmitter
Exploded Isometric View
II
V-40255 Dummy Log Speed Transmitter
Sheet 1 - Assembly and Details
III


LIST OF DRAWINGS (CONT'D.)

Mfgr's. Drawing No. Title Page No.
V-40255 Dummy Log Speed Transmitter
Sheet 2 - Parts List
IV
V-40256 Dummy Log Distance Transmitter
Sheet 1 - Assembly and Details
V
V-40256 Dummy Log Distance Transmitter
Sheet 2 - Assembly-Section Views
VI
V-40256 Dummy Log Distance Transmitter
Sheet 3 - Parts List
VII
S-502023 Dummy Log Distance Transmitter
Schematic Wiring Diagram
VIII
S-502681 Dummy Log Speed Transmitter
Lubrication Diagram
IX
S-502682 Dummy Log Distance Transmitter
Lubrication Diagram
X
XS-46426 Interconnection Wiring Diagram
for Dummy Log Speed and Distance
Transmitters
XI


1
 

I. DESCRIPTION OF THE INSTRUMENTS

1. GENERAL

The Dummy Log Speed Transmitter, Drawing V-40255 and BW-00223, and the Dummy Log Distance Transmitter, Drawing V-40256 and BW-00224, are separate units comprising a ship's Dummy Log System. Generally, the Speed Transmitter is located in a position convenient to the shaft revolution indicator and the Distance Transmitter in the Interior-Communications Room. The Dummy Log System may be used for any of the following purposes: (1) in case of damage to the Underwater Log System, (2) to simulate an Underwater Log System for training purposes, and (3) for use aboard ships which are not equipped with Underwater Log Systems.

1-1 Dummy Log Speed Transmitter: The Speed Transmitter is a manually operable self-synchronous generator type instrument. The instrument is designed to transmit, by angular displacement of the generator rotor, ship speed indications to the receiving motor of the Dummy Log Distance Transmitter, underwater log indicators and other instruments requiring ship speed indications or inputs. The capacity of the type "B" generator is sufficient to operate a total of 12 type "M" indicator motors.

1-2 Dummy Log Distance Transmitter: The Distance Transmitter is an instrument designed to receive angular speed inputs from the Speed Transmitter and to transmit rotary motion, at a rate proportional to the setting of the Speed Transmitter. The ship speed indications are received by the self-synchronous receiving motor in the Distance Transmitter. The rotor of the motor is displaced angularly, the amount of displacement being dependent upon the speed setting of the Speed Transmitter. This angular displacement is converted by electromechanical means into rotary motion, at a rate of 360 revolutions for each nautical mile of the Speed Transmitter. The rotary motion is transmitted, by a type "B" self-synchronous generator in continuous rotation, for any given setting of the Speed Transmitter, to the Dead Reckoning Analyzer.

A 115 volt 60 cycle single phase supply is necessary to operate the system.

NOTE: A complete description of the theory and operation of self-synchronous transmitting generators and receiving motors will be found in Section VI.

2. DUMMY LOG SPEED TRANSMITTER, DRAWINGS #V-40255 AND BW-00223

This unit consists of a type "B" self-synchronous generator geared to a dial graduated in knots. The unit is housed in a watertight case with a hand crank in the case cover to rotate the generator.

2-1 The Transmitter Assembly: The transmitting generator (1) with a worm wheel (79) attached to its shaft and held in brackets (34) is mounted on the rear surface of a common mounting plate, the spider (2). On the front surface, the dial mounting disc (45), worm wheel (46) and the drive worm (19) are mounted. An air damping mechanism geared to the dial worm shaft (19) is also mounted on the front surface of the mounting plate.



2
 
Parts attached to the mounting plate (2) such as the generator brackets (34), the air damping mechanism, bearing bracket (78), and the dial pointer, mount (44) are doweled to the mounting plate in addition to being held by mounting screws. These dowels prevent shifting of the parts under shock or vibration.

One end of the dial mounting disc drive worm shaft (19) and the generator drive worm shaft (29) is assembled in the bearing bracket (78) attached to the mounting plate (2). On one end of each shaft is a miter gear (76) which is rotated by a third miter gear (76) attached to the main drive shaft (27). These three gears bear a 1:1 ratio and cause the generator and dial mounting disc to turn simultaneously. The worms (19 and 29), in mesh with worm wheels (46 and 79), rotate the dial mounting disc and the generator in a 42:1 ratio causing each to rotate at the same speed.

A stop (28) is incorporated in the bearing bracket (78). This stop prevents the dial (71) and generator (1) from being turned below the zero speed indication when the transmitter speed output is being reduced and limits the dial and generator rotation to 360°. The threaded collar (28) travels back and forth on the threaded worm gear shaft (29) as the shaft is turned. Pins (94) in opposite sides of the collar (28) stop against a pin (77) at each end of its travel, preventing further rotation. A screw (61) in the outside of the collar engaging a slot in the side of the bearing bracket (78) prevents the collar from rotating.

The terminal strip (4) with five terminals, is mounted on the mounting plate for connecting the primary and secondary leads of the generator. The terminals on the strip are marked Y, YY, denoting the stator (primary) leads and Y1, Y2, Y3, denoting the rotor (secondary) leads. The leads from the generator have metal tabs attached. Stator leads are marked S1, S2, and the rotor leads R1, R2, R3. All are connected to the terminal strip as shown in the wiring diagram (62), on Drawing #V-40255, sheet 1.

The transmitting generator (1) is set to electrical zero when the stop collar (28) is stopped by the pin (77) at the forward end of the travel. With the generator set in this position, the speed dial (71) is assembled on the dial mounting disc (45) with the zero mark directly under the dial pointer (41)

A light socket (53) with a 115 v. Navy type (C.S. 5/17) clear glass lamp (55) for dial illumination is attached to the mounting plate. The lamp leads are attached to the Y and YY terminals on the terminal board as shown on the wiring diagram (62).

A reference line is provided, in the form of a shadow, cast on the back of the dial by a wire (40) held in the pointer mount (44) between the dial and the lamp (55).

Lifting handles (95) are attached to the mounting plate (2) for removing the mechanism from the case.

2-2 Speed Transmitter Dials: All dials are white translucent plastic with knot and 0.2 knot graduations, indicated by black markings. Dials furnished with the Speed Transmitters accompanied by Distance Transmitters have speed ranges listed below as type DL-40 or DL-25. All Speed Transmitters not accompanied by Distance Transmitters have dials with speed ranges listed



3
 
as type DL-35, BDL-35, BDL-25 or DL-30. These Speed Transmitters not accompanied by Distance Transmitters can be identified by the suffix "A" after the serial number on the nameplate.

The units furnished will be equipped with one of the dials listed below.

TYPE OUTPUT
SPEED RANGE
SCALE
CHARACTERISTICS
DEGREES PER KNOT
DL-40 0-40K Linear 9.00
DL-35 0-35K 0-3 Knots (10.43 Degrees) Non-Linear
3-35 Knots Linear 10.43
BDL-35 0-35K Non-Linear Non-Linear
DL-30 0-30K 0-2 Knots (12 Degrees) Non-Linear
2-30 Knots Linear 12.00
DL-25 0-25K Linear 14.40
BDL-25 0-25K Non-Linear Non-Linear

2-3 Dummy Log Speed Transmitter Case: The case (8) and cover (9) are machined aluminum castings. Four lugs cast integral with the rear outside corners of the case contain bolt holes for attaching the transmitter to a bulkhead. Two lugs are provided in opposite inside corners for attaching the mounting plate 2) which is held in position by the four screws (65). Two 1-1/4" (I.P.S.) tapped holes (closed by plugs (60) during shipment), one located in the top and one in the bottom, are provided for attaching the terminal tube fitting through which the connecting wiring is introduced. The wedge shaped bead on the cover engages a rubber gasket (12) in the case (8) forming a watertight seal when the cover is bolted in place. The cover is held on the case by four cover bolts (11) engaging threaded steel inserts (10). A seat screw (58) in the bottom of the case provides means of draining moisture caused by condensation, when necessary.

Assembled with the cover is a hand crank (80) and key shaft (26) for rotating the transmitter mechanism. The shaft opening through the cover is made watertight by two washers (25) on the shaft. One washer is held against the shaft key and the other against a shoulder in the cover bushing (22) by a spring (23). When the cover (9) is bolted in place on the case, the key shaft engages a slot in the main drive shaft (27) providing a positive drive. The mounting plate (2) is doweled to the lugs inside of the case (8) and the cover (9) is also doweled to the case. Dowel pins (74) are used in both.

At the top of the cover (9) is the dial window made watertight by a rubber gasket (37) between the tempered glass window (38) and the window retainer (39).

The nameplate (20) is attached to a boss on the cover by four machine screws.

NOTE: Three warnings are engraved on the nameplate.

To Secure: Set Speed Transmitter Dial at 1/2 scale. Allow 2-1/2 minutes before opening supply circuit.



4
 
To Start: Set dial to 1/2 scale before closing supply circuit.

Do not rotate this dial faster than 8 knots per minute.

For proper operation of the Dummy Log System and to prevent improper operation of the Distance Transmitter, these warnings must be adhered to.

A schematic wiring diagram (62) showing the internal connections is placed inside the cover of the case.

2-4 Spare Parts: A list of the spare parts furnished with the Dummy Log Speed Transmitter is shown on Drawing #V-40255, sheet 2.

3. DUMMY LOG DISTANCE TRANSMITTER, DRAWING #V-40256 AND BW-00224

The Distance Transmitter consists of four units, (1) the receiving unit, (2) the reversible motor, (3) the synchronous motor, disc and roller mechanism and (4) the transmitting generator drive mechanism and transmitting generator. All units are mounted on a common mounting plate (base plate-87) and are doweled to prevent shifting of the parts under shock and vibration. The mechanism is enclosed in a dripproof case designed for bulkhead mounting.

3-1 The Receiving Unit: This unit consists of the type "M" self-synchronous receiving motor (1), the cam disc and roller arm assembly (11), and the heart-shaped cam (117) and its integral stop support (144).

The receiving motor (1) is electrically connected to the Dummy Log Speed Transmitter generator. The cam disc and roller arm assembly (11) is attached to the receiving motor shaft and turns with the rotor. The roller (76) in the arm assembly is held against the outside edge of the heart-shaped cam (117) by the tension of the cam roller arm spring (78). The heart-shaped cam (117) with its integral stop support (144), the contact finger (142) and contacts (141) are free floating on the shaft (130). The shaft (130) is centered at one end in the hub of the cam disc (11) and held at the other end by setscrews in a bushing (129).

3-2 The Reversible Motor Unit: This unit consists of the contact arm assembly (131, 139, 79), brush rings (134, 135, 136), brush springs (152), worm wheel (128), reversible motor (15), suppressor (153), and the reducing gear train consisting of the motor pinion (115) and gears (40, 194, 150, 75, 80, 193, 10, 73). The reducing gear train connects the reversible motor (15) to the brush ring and contact arm assembly and the jack screw (159).

Pressed on a sleeve (137) are the contact arm assembly (79, 131, 139), brush rings (134, 135, 136) with insulating washers (124, 127) and worm wheel (128), (see drawing #V-40256, Sheet 1, Cam Disc and Contact Detail). This sleeve with the assembled parts is mounted on and is free to turn on the shaft (130). The position of the sleeve on the shaft (130) is such that the contacts (141) on the stop support (144) lie between the contact arms (79) and contacts (139) on the sleeve (137) forming a single-pole



5
 
double-throw switch which is electrically connected through the brush rings (134, 135, 136) and brush springs (152) to the shading coil circuits of the reversible motor (15).

The reversible motor (15) is mounted on a bracket (18) by four mounting screws (206). The pinion (115) on the shaft of the motor engages the spur gear of the gear and worm assembly (40). The worm (40) engages the worm wheel (194) on the cross shaft (150) causing a speed reduction between the motor pinion (115) and worm wheel (128) on the sleeve (137).

The worm on the cross shaft (150) meshing with the worm wheel (128) turns the brush rings (134, 135, 136), the contacts (139, 141) and the heart-shaped cam assembly (117). The pinion (75) on the end of the cross shaft (150) meshes with pinion (80) driving the jack screw through the pinion (193), idler gear (10) and the jack screw gear (73). These gears are mounted on the roller mounting bracket (48).

3-3 The Synchronous Motor, Disc and Roller Mechanism: This unit consists of the synchronous motor (41) and roller disc (64) mounted on a carriage. The roller shaft (49) mounted in bracket (48) comprises the balance of the unit.

The carriage consists of the motor mounting bracket (28) on the under side of which are attached two slide rods (157, 158) which are free to slide back and forth in oilite bushings (94) in the opposite sides of the mounting bracket (48). Between the slide rods (157, 158) is the jack screw nut in a lug cast integral with the motor mounting bracket (28). The nut is threaded and engages the threads of the jack screw (159). The shaft end of the jack screw (159) is supported by an oilite bushing in the bracket (48). The jack screw driving gear (73) is attached to the shaft end of the jack screw. The jack screw (159) drives the carriage backward or forward as the screw is rotated through the reducing gear train by the reversible motor. Mounted on the top of the carriage (bracket-28) is the synchronous motor (41) and capacitor (198). The synchronous motor (41) drives the disc shaft (65) at right angles to it through the miter gears (88) on the shaft of the synchronous motor and the disc shaft (65).

The disc shaft (65) is contained in a housing cast integral with the carriage (28). Two ball bearings (62) fitted into the housing, support the disc shaft. The disc spring (69) on the shaft between the retaining washers (67) maintains a constant pressure on the shaft pressing it toward the roller shaft (49). The disc plate (66) is mounted on the end of the disc shaft (65) and the roller disc (64) is attached to the disc plate (66) by three disc studs (63).

Mounted in each end of the bracket (48) are two ball bearings (62) supporting the roller shaft (49). The axis of the roller shaft (49) is parallel to the plane of rotation of the roller disc (64) from which the roller shaft receives rotary motion.

3-3-1 Micro-Switches: Three micro-switches (19) are mounted on the mounting plate (87). One switch is mounted singly and two are paired, one above the other.



6
 
The singly mounted switch is connected in the counterclockwise rotation circuit of the reversible motor (15). This switch is operated by an adjustable trip screw (83) in the end of slide rod (157), pressing against the switch button. The top switch of the two mounted one above the other is connected in the clockwise rotation circuit of the reversible motor (15) and the bottom switch is connected in the circuit of the synchronous motor (41). These two switches are opened by the two adjustable trip screws (24) in the trip arm (22) mounted on the end of slide rod (158).

3-4 The Transmitter Generator Drive Mechanism and Generator: The generator drive mechanism consists of a differential (43, 57, 42, 71, 72), the rheostat (45), the follow-up motor (56) and the generator (162).

The differential, shown in the isometric drawing #BW-00224, connects the roller shaft (49) to the shaft of the generator (162). This differential consists of the two sun gears (43, 57) and the casing. The casing is an assembly composed of four identical planetary pinions (42-a-b), the plate gear (71) and the plate (72) with four posts attached.

One sun gear (43) is mounted on the roller shaft (49). The other sun gear (57), part of an assembly (57) composed of the sun gear, the hub and the large gear (57), is mounted on the shaft of the generator (162). The plate (72) with posts is mounted on the hub of the sun gear (43). The plate gear (71) is mounted on the hub of the sun gear (57). The plate and plate gear are free to turn on the hubs of their respective gears. The planetary pinions (a-b) are mounted in bearings in the plate and plate gear. The plate gear and plate with the pinions are held together by the screws (165) in the posts.

The planetary pinions (a-b) are free to rotate in their bearings. The pinions (a) mesh with the sun gear (43) and are also in mesh with pinions (b). Planetary pinions (b) mesh with the sun gear (57), forming an indirect coupling between the roller shaft (49) and the generator (162).

The plate gear (71) meshes with the rheostat gear (9) turning the shaft and contact arm of the rheostat (45). The rheostat is connected in series with the field coil of the follow-up motor (56).

A follow-up motor (56) is geared to the generator through pinion (86) on the motor shaft and the large gear of the assembly (57) attached to the shaft of the generator (162). The follow-up motor bracket (53) attached to the generator brackets (38) 60) serves as a mounting for the follow-up motor. A fan is attached to the free end of the motor shaft to provide cooling of the motor. The generator (162) is mounted in the two mounting brackets (38, 60) and held to the mounting plate (87) by the four bracket bolts (37).

3-5 Internal Wiring: Internal wiring connections are shown in the Schematic Wiring Diagram (155), which is attached to the inside of the cover (89). A master wiring diagram drawing #502023 showing the various units of the Distance Transmitter in their proper relationship is also included with the drawings. The internal wiring is connected to two terminal strips (31, 47) mounted on the base plate (87).



7
 
One, a terminal strip (31) with five terminals is placed at the left side near the receiving motor (1). Five receiving motor (1) leads are marked with metal tabs; S-1 and S-2 denote the stator leads, and R1, R2, and R3 the rotor leads. These five leads are connected to terminal strip (31); S-1 and S-2 to the 115 v. primary terminals marked Y and YY and R1, R2, and R3 to the secondary terminals marked Y1, Y2, and Y3.

The other, a terminal strip (47) with seven terminals, is attached to the base plate at the lower right-hand corner. The leads of the transmitting generator (162) are marked with metal tabs with the same symbols as the receiving motor (1). The stator leads S-1 and S-2 are connected to the primary 115 v. terminals marked 2Y and 2YY and the rotor leads marked R1, R2, and R3 are connected to the secondary terminals marked 2Y-1, 2Y-2, 2Y-3. The leads of the synchronous motor (41) are connected to terminals Y-10 and YY-10 on this terminal strip.

3-6 The Dummy Log Distance Transmitter Case: The case (33) and cover (89) are machined aluminum castings. Four external lugs cast integral with the rear of the case contain bolt holes for mounting the instrument. The mounting plate (87) on Which the mechanism is mounted is doweled and bolted to four interior bosses, one in each corner. Four dowel legs (174) screwed into the corners of the base plate engage a hole in each boss. When the mechanism is being replaced in the case after removal for inspection or servicing, the dowels guide and help hold the plate in position until the base bolts (35) have been inserted and tightened. Two handles (166) are attached to the mounting plate to facilitate removing the mechanism from the case.

The cover (89) is held on the case by ten cover bolts (90). Ventilation of the case is provided through two openings with ventilating shields (147) in the top and three holes covered by screens (182) in the bottom. A nameplate (97) is attached to the front of the cover by four screws (96).

3-7 Spare Parts: A list of all spare parts furnished with each Dummy Log Distance Transmitter is shown on Drawing #V-40256, sheet 3.



8
 

II. THEORY OF OPERATION

1. DUMMY LOG SPEED TRANSMITTER, DRAWINGS #V-40255 AND BW-00223

Since a ship's speed is indicated in knots, (nautical miles per hour) the speed dials are graduated, through 360 degrees, from 0-25 knots in a 25 knot Dummy Log System and from 0-40 knots in a 40 knot system.

The self-synchronous generator (1) is set to electrical zero when .the stop collar (28) is stopped at the forward end of its travel by the stop pin (77). The speed dial (71) is attached to the dial mounting disc (45) so that the zero speed indication is directly under the dial pointer when the generator is in the electrical zero position.

The hand crank (80, 83) is geared to the dial mounting disc (45) and the generator (1) by their respective worms (19; 29) and worm wheels (46, 79). This worm and worm wheel arrangement forms an effective lock between the two members preventing the generator from being turned by any reaction from the receiver motors.

The dial and the generator are rotated by the hand crank in a 1:1 ratio. As the transmitter dial is rotated from zero to various speed indications the rotor of the generator is displaced angularly. The angular displacement of the generator corresponds to the various dial speed indications through 3600. Any angular position of the generator (1) is repeated by the receiving motor of the Distance Transmitter to which it is electrically connected and by any other receiving motor connected in circuit.

Where the ship has a speed acceleration and deceleration curve, all personnel concerned with the operation of the Dummy Log System should familiarize themselves with the proper operation of the Speed Transmitter and the use of this curve,- When a ship is changing speed, either increasing or decreasing, the speed dial (71) should not be rotated faster or slower than the actual speed changes. If the dial is rotated in this manner the operation of the system will approximately duplicate the actual changing conditions.

The air damping mechanism is incorporated in the Speed Transmitter to help prevent rapid rotation of the speed dial and generator. When the system is in operation, the speed dial must not be turned faster than 8 knots per minute. The reason for this is given in paragraph 2 of this section.

2. DUMMY LOG DISTANCE TRANSMITTER, DRAWINGS #V-40256 AND BW-00224

The purpose of the Distance Transmitter is to convert the angular output of the Speed Transmitter into rotary motion at the rate of 360 revolutions per nautical mile. Therefore, if the speed indication is one knot (one nautical mile per hour), the output of the Distance Transmitter in a 40 knot system will be 360 revolutions per nautical mile or dividing by 60 minutes, 6 R.P.M. Similarly, if the speed indication is 40 knots, the output of the Distance Transmitter would be 6 R.P.M. times 40 or 240 R.P.M. If this speed were held constant for one hour, the total revolutions would be 240 R.P.M. times 60 minutes or 14,400 (i.e. 360 revolutions x 40 knots).



9
 
Likewise, in the 25 knot system, the output of the Distance Transmitter with a 25 knot speed indication, will be 6 R.P.M. times 25 or 150 R.P.M. If this speed were held constant for one hour the total revolutions would be 150 R.P.M. times 60 minutes or 9000 (i.e. 360 x 25).

Varying the output of the Distance Transmitter is accomplished by the disc (64) and roller (49) mechanism. The disc (64) is rotated at a constant speed by the synchronous motor (41) through the miter gears (88). Roller and Shaft (49) are rotated by the disc (64). The disc (64) and the synchronous motor are moved back and forth in linear motion. When the roller (49) is in the center of the disc (64), it receives no motion and does not rotate. As the center of the disc is moved away from the roller (49), the rate of rotation of the roller increases. When the disc has reached the end of its travel and the roller is near the edge of the disc, the rate of rotation of the roller is maximum.

The theory of the Distance Transmitter is described in the same sequence as the description (Section I), that is (1) the Receiving Unit (2) the Reversible Motor, (3) the Synchronous Motor, Disc and Roller. Mechanism and (4) the Transmitting Generator Drive Mechanism and the Transmitting Generator.

2-1 The Receiving Motor Unit: The rotor of the self-synchronous receiving motor (1), cam disc (11) and the cam roller arm (see Exploded Isometric Drawing BW-00224) turn and assume the angular position dictated by the transmitting generator in the Dummy Log Speed Transmitter. As the roller (76) in the roller arm turns on the edge of the heart-shaped cam (117), it moves the cam and its integral stop support (144) which is free floating on the shaft (130), but this movement is restricted by the stop support (144) and its contacts (141) which lie between the two contacts (139) in the contact arm assembly (139, 79, 131). These three contacts (141, 139) form the single-pole double-throw switch mentioned in Section I.

2-2 The Reversible Motor Unit: This single-pole double-throw switch being electrically connected through the brush rings (134, 135, 136), the brush springs (152) and plug (109) to the shading coils of the reversing motor (15), controls the direction of rotation of the motor. The direction of rotation of this motor depends on which side of the switch is closed by the contact (141) as the heart-shaped cam (117) is moved by the can arm roller assembly (11) in response to the motion of the receiving motor (1). If the receiving motor (1) is turning in response to a speed increase of the Speed Transmitter, the roller (76) displaces the heart-shaped cam in a direction to close the counterclockwise rotation circuit of the reversible motor (15). If the receiving motor (1) is turning in response to a speed decrease, the action of the roller is opposite and the clockwise rotation circuit is closed. When the receiving motor is at rest and the speed indication is constant, the roller (76) is in the low position on the heart-shaped cam. In this position, the contacts are open and both the clockwise and counterclockwise circuits are de-energized.

The reversible motor (15) serves two purposes. First, through the reducing gear train consisting of the pinion on the shaft of the reversible motor (15) and the gears (40, 194, 150, 128), it turns the sleeve (137) on Which



10
 
are assembled the brush rings (134, 135, 136) and the contact arm assembly (139, 131, 79). This sleeve turns on the shaft (130) and causes the heart-shaped cam (117) with its integral stop support (144) and contacts (141) which are free floating on shaft (130) to turn. The turning of these units is always in a direction to cause the single-pole double-throw switch to follow slightly behind the cam disc roller (76) as it is turned by the receiving motor (1). When the rotor of the receiving motor (1) comes to rest, the heart-shaped cam (117) continues to turn until the low position is brought directly under the roller (76). The contacts of the single-pole double-throw switch then open and rotation of the reversible motor (15) ceases.

The gear reduction between the reversible motor (15) and the single-pole double-throw switch is such that the switch and the heart-shaped cam (117) cannot follow the cam arm roller (76) faster than 8 knots per minute. For this reason the notation is placed on the nameplate of the Speed Transmitter not to rotate the dial faster than 8 knots per minute. If the speed dial of the Speed Transmitter is rotated faster, the can arm roller (76) will be driven over the high point of the heart-shaped cam (117). This will cause the moving contact (141, 142) to close the other side of the single-pole double-throw switch and the rotation of the reversible motor (15) will change to the opposite direction.

Secondly, the reversible motor (15) through the reducing gear train consisting of the motor pinion and gears (40, 194, 75, 80, 193, 10, 73) rotates the jack screw (159) which moves the synchronous motor carriage (motor mounting bracket 48) back and forth. Therefore, the turning of the single-pole double-throw switch and the rotation of the jack screw is simultaneous. When the contacts of the switch are open and the reversible motor is at rest, the jack screw is also at rest. The gear reduction between the reversible motor (15) and the jack screw (159) is such that the screw is rotated in direct relation to the turning of the single-pole double-throw switch.

A suppressor (153) is connected to the reversible motor terminals as Shown in the wiring diagram (155) (see drawing #V-40256 sheet 2) to reduce arcing of the switch contacts.

2-3 The Synchronous Motor, Disc and Roller Mechanism: The disc shaft (65) and the disc (64) are rotated by the synchronous motor (41) at a constant speed, 60 R.P.M. The speed of the synchronous motor (41) and the disc shaft (65) are equal, as the miter gears (88) bear a 1:1 ratio. This speed is held constant by connecting the motor to a 115 volt 60 cycle controlled frequency supply circuit which does not vary more than ± 1/10%. A capacitor (198) is connected in the synchronous motor circuit to provide quick and even starting. The synchronous motor (41) is in constant rotation as long as the switch in the main 115 v. supply circuit and the contacts of the micro-switch (19) are closed.

The receiving motor (1) is set to electrical zero when the jack screw (159) has positioned the synchronous motor carriage (28) so that the center of the disc (64) is directly over the center line of the roller (49) (see drawing #V-40256 sheet 1). In this position the roller (49) receives no motion from



11
 
the disc (64). As the receiving motor (1) is turned from 0 to higher speed indication by the speed transmitter generator, the reversible motor (15) rotates the jack screw (159) and drives the carriage (28) in a straight line so that the center of the disc (64) moves away from the roller (49). Friction between the disc (64) and the roller (49) causes the roller to rotate. As the center of the disc (64) moves away from the roller (49) the speed of the roller increases. When the carriage (28) and disc (64) in a 0-40 knot system has moved 1.25 inches the speed of the roller is 240 R.P.M.

In a 0-25 knot system the linear distance traveled by the carriage (28) and roller disc (64) is 25/40 of 1.25 inches or .781 inches and the speed of the roller is 25/40 of 240 R.P.M. or 150 R.P.M. Reducing the travel from 1.25 inches to .781 inches in a 0-25 knot instrument is accomplished by replacing gears 75 and 80 with two gears of different ratio (identical to the miter gears (88).

When the speed indications of the Speed Transmitter are being reduced, the rotation of the reversible motor (15) and the jack screw (159) is in the opposite direction and the center of the disc (64) is moved toward the roller (49) and the speed of the roller is reduced.

End play between the hub of the jack screw drive gear (73) and the jack screw bushing is held to the minimum which will allow the jack screw (159) to rotate freely. This end play must not be more than .006 of an inch as the accuracy of the speed output by the Distance Transmitter will be affected (see Maintenance Section IV paragraph 4).

2-3-1 Micro-Switches: The three micro-switches (19) are safety devices, their contacts being normally closed. The stop screw (83) in the slide rod (157) is adjusted to open the singly mounted micro-switch connected in the counterclockwise rotation circuit of the reversible motor (15). This switch opens when the dial of the Speed Transmitter is set at 24.6 knots in a 0-25 knot system and at 39.6 knots in a 0-40 knot system. At these dial settings the speed of the roller (49) is approximately 150 and 240 R.P.M. respectively.

The two trip screws (24) in the trip arm (22) attached to slide rod (158) are adjusted to open the paired micro-switches (19) successively. The top micro-switch (19) of this pair, in the clockwise rotation circuit of the reversible motor, is set to open the switch when the speed transmitter dial is set between 0.6 and 0.8 knots, stopping the reversible motor (15) and the carriage (28) before the speed transmitter dial reaches the zero position.

The bottom switch (19), in the synchronous motor circuit opens just before the top switch, stopping the motor to prevent unnecessary wear between the roller disc (64) and the roller (49).

2-4 The Distance Transmitter Generator Drive Mechanism and Generator: The transmitting generator (162) is rotated by the disc and roller mechanism (64, 49) through a spur gear differential. Since the power output of the disc and roller is not great enough to drive the generator plus its external load, the necessary additional torque is supplied by the follow-up motor (56).



12
 
The object of transmitting the rotary motion of the roller (49) through 1 the differential gearing (43, 42, 57) is to vary the position of a rheostat controlling the power output of the follow-up motor (56) so that the generator will always be driven at the speed of the roller.

2-4-1 The Differential: The principal of the mechanical movement of the differential may be better understood by referring to the drawing BW-00224. The roller shaft (49) rotates the sun gear (43) attached to it causing the two pinions (a) meshing with the sun gear to rotate. These pinions (a) also mesh with and drive the two pinions (b) meshing with and driving the other sun gear (57). It will be noted by following the direction arrows on the pinions and gears that the direction of rotation of the sun gear (57) attached to the shaft of the generator (162) is opposite to that of the driving sun gear (43). When the speed of the sun gears is equal and opposite the differential casing (42, 71, 72) remains at rest.

When the speed of the sun gears tends to become unequal; that is, the generator sun gear (57) attempts to lead or lag behind the driving sun gear (43) or vice versa, this unequal speed condition causes the rotating pinions to roll around the sun gears causing the casing (42, 71, 72) to turn. This turning of the differential casing gear (71), which is in mesh with the rheostat gear (9), applies a torque, turning the shaft and contact arm of the rheostat (45).

2-4-2 The Follow-Up Motor and Rheostat: This motor (56) is an induction type, the field coil being connected in series with the rheostat (45) which varies the torque of this motor. The field coil and rheostat are permanently connected across the 115 volt primary circuit as shown in the wiring diagram (155) (see drawing #V-40256, sheet 2). Speed output of the follow-up motor is varied from zero to 2400 R.P.M. maximum by increasing or decreasing the resistance in the field coil circuit.

As it becomes necessary for the follow-up motor to deliver more power to drive the generator (162) at the same speed as the roller (49), the turning action of the differential case causes the rheostat shaft and arm to turn in the direction to decrease the resistance in the field coil circuit. When less power is required, the turning notion of the casing is in the opposite direction increasing the resistance and causing the follow-up motor to deliver less power.

Therefore, at all speeds of the roller (49) the power output of the follow-up motor is that required to drive the generator (162) at the speed of the roller.

2-4-3 The Transmitter Generator: Being in continuous rotation the generator (162) is not set to the electrical zero position. The R.P.M. speed output of this generator (162) is transmitted to the self-synchronous receiving motor located in the Dead Reckoning Analyzer of the Dead Reckoning Tracer, which is also in continuous rotation.

3. SECURING AND STARTING THE DUMMY LOG SYSTEM

IT IS MOST IMPORTANT WHEN CLOSING DOWN THE DUMMY LOG SYSTEM TO PROCEED AS FOLLOWS: BEFORE OPENING THE 115 V. SUPPLY CIRCUITS IN EITHER INSTRUMENT, THE SPEED DIAL OF THE SPEED


13
 
TRANSMITTER MUST BE SET TO THE HALF SCALE INDICATION (12.5 KNOTS OR 20 KNOTS). AFTER ALLOWING AT LEAST 2-1/2 MINUTES FOR THE DISTANCE TRANSMITTER TO FOLLOW THE SPEED TRANSMITTER, THE POWER SUPPLY MAY BE DISCONNECTED.

UPON STARTING THE SYSTEM AGAIN, THE SPEED TRANSMITTER DIAL SHOULD BE SET TO HALF SCALE BEFORE ENERGIZING THE CIRCUITS. CLOSE THE 115 V. SUPPLY CIRCUIT. THE SPEED TRANSMITTER DIAL MAY THEN BE ROTATED TO ANY DESIRED POSITION AND THE DISTANCE TRANSMITTER WILL FOLLOW.

THESE INSTRUCTIONS ARE CONTAINED ON THE NAMEPLATE OF THE DISTANCE TRANSMITTER AND MUST BE FOLLOWED FOR THE PROPER OPERATION OF THE DUMMY LOG SYSTEM.

Failure to comply with these instructions will cause the Distance Transmitter to become 180° out of phase with the Speed Transmitter. Should this condition exist, rotate the speed transmitter dial above half scale and allow 2-1/2 minutes to elapse so that the Distance Transmitter will come in phase with the Speed Transmitter. The system may then be operated in the usual manner.



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III. INSTALLATION

1. GENERAL

Experience has shown that in many cases where trouble is encountered in Interior-Communications Systems, it can be traced to mishandling during the initial installation. For this reason, it is extremely important that great care be exercised in handling the instruments and that instructions be followed carefully.

When unpacking the instruments give each a visual inspection to see that they have not been damaged during shipment.

In selecting a location on a bulkhead to mount the instruments, the space selected should not be adjacent to a source of heat. Abnormal heating of the instruments may cause severe damage. The location should also be determined by convenience for wiring and servicing.

Since the equipment may have been stored before being installed, it is advisable to oil each instrument in accordance with instructions under Maintenance Section IV. It should be remembered that accurate operation of the Dummy Log System depends upon freedom from friction between all moving parts.

2. DUMMY LOG SPEED TRANSMITTER, DRAWING #V-40255 and XS-46426

It will be more convenient to remove the Speed Transmitter mechanism from the case (8) while it is being mounted on the bulkhead and the connecting wiring is being introduced into the case. First remove the cover bolts (11) and the cover (9). Unscrew the four machine screws (11) holding the mechanism in the case, and carefully remove the mechanism using the lifting handles (95) so that no damage is caused to the assembled parts. Mount the case in the location selected on the bulkhead, using four 9/16" bolts.

To wire the Speed Transmitter to the Distance Transmitter and any other receiving motor:, refer to the Interconnection Wiring Diagram XS-46426. First remove the pipe plug (60) in the top or bottom of the case whichever is more convenient. Attach the terminal tube fitting through which the necessary wires are introduced into the case (8). Leave enough wire so that connections may be made to the terminal strip on the front of the spider. Replace the mechanism in the case and the four machine screws (11) holding it in place. Connect the respective wires to the marked terminals on the terminal strip (4). Clean all dirt and chips from the case and lubricate the mechanism in accordance with the instructions given under Maintenance Section IV. Attach the cover (9) with the four cover bolts (11) making sure the key on the end of the hand crank shaft (26) engages the slot in the main drive shaft (27).

3. DUMMY LOG DISTANCE TRANSMITTER, DRAWING #V-40256 AND XS-46426

It will also be more convenient to remove the Distance Transmitter mechanism from the case (33) while it is being mounted on the bulkhead and the



15
 
incoming wiring is being introduced into the case. First, remove the 10 cover bolts (90) and the cover (89). Unscrew the four mounting bolts (35) and lift the mechanism from the case using the lifting handles (166). Protect the mechanism from damage and from any dirt or chips falling into it while it is removed.

Mount the case on the bulkhead using four 5/8" bolts, with the ventilator shields on top. Remove the pipe plug (12) in the top or bottom whichever is most convenient. Attach the terminal tube fitting through which the necessary wires are introduced into the case (33). Leave enough wire to make the necessary connections to the terminal strips (31, 47) located on the front of the base plate. Replace the mechanism in the case and the four machine screws (35) holding it in place. Connect the respective wires to the marked terminals on the terminal strips (31, 47). Oil the mechanism of the Distance Transmitter in accordance with the instructions given under Maintenance Section IV. Remove all dirt and chips from the case and replace the cover and cover bolts.

Drill four mounting holes in the bulkhead in accordance with the dimensions shown in drawing #V-40256. Mount the case using four 5/8" volts, placing the ventilator shields on top.



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IV. MAINTENANCE

1. GENERAL, COMPLETE SYSTEM

Possible causes of trouble in the system may be avoided by careful maintenance. Improper operation often may be eliminated by proper cleaning and lubricating the various units. Causes of excessive friction such as tight gear mesh in any of the units, dirty electrical contacts and abnormal wear between parts may be located during a routine maintenance inspection.

The Speed Transmitter should be removed from the case periodically for inspection, cleaning and oiling according to the lubrication instructions below.

The Distance Transmitter must be inspected, cleaned and lubricated at closer intervals.

Some of the possible trouble indications other than from mechanical sources are given below. Possible mechanical sources of error are indicated under the particular unit.

Failure of the Dummy Log System to Function: Check the primary terminals on the terminal board of the Speed Transmitter and the three supply circuits of the Distance Transmitter to see that the 115 volt power circuits are energized. Should the system still fail to function, one of the self-synchronous generators or the motor may be at fault (see Self-Synchronous Generators and Motors, Section VI). The reversible motor (15) in the Distance Transmitter may not be functioning properly or its single-pole double-throw switch contacts may need cleaning. To check the reversible motor, first hold a screw driver against the frame laminations. Failure to feel vibrations will indicate that the motor is not being energized by the 115 v. supply current. If the motor is found to be energized, the switch contacts and the slip rings should be examined and any dirty spots removed with crocus cloth. The direction of the motor depends upon which of the two shading coils is energized; therefore, a break in one coil would be indicated by the failure of the motor to reverse its direction of rotation when the single-pole double-throw switch functioned. Should excessive arcing occur at the contacts (139, 141), a capacitor or resistor in the suppressor (153) may be at fault.

Should the disc (64) and roller (49) in the Distance Transmitter Unit not rotate, check for failure of the synchronous motor (41) or its capacitor. If the transmitting generator (162) in the Distance Transmitter does not rotate or give the proper speed output, check for failure of the follow-up motor (56) and rheostat (45).

Should the receiving motor (1) in the Distance Transmitter turn opposite to the speed transmitter generator, reverse leads Y-1 and Y-3.



17
 
2. TYPE OF LUBRICANT TO BE USED FOR LUBRICATION

Good quality machine oil, Navy Symbol 2110, and Norma Hoffmann Ball Bearing Grease #66 (Navy Specs. 14-L-3, Grade 2; Standard Stock No. 14-L-125) should be used to lubricate the instruments as described in this section paragraphs 3 and 4. In general, oil should be used for all bearings and grease for the gear teeth.

A drop of oil is defined as that amount which will drop freely from a #16 gauge bare wire.

3. DUMMY LOG SPEED TRANSMITTER, DRAWING #V-40255

Proper operation of the Speed Transmitter depends upon all moving parts being free from friction. To insure this, the mechanism should be removed from the case for inspection and oiling every six months.

Remove the cover bolts (11) and lift off the cover (9). Remove the four mounting plate bolts (65) and lift the mechanism from the case (8) by means of the lifting handles (95). Care should be exercised in this removal so that parts of the mechanism will not be damaged.

Make a visual inspection all gears, worms, and rotating parts to see that unnecessary wear between meshing gears and other parts is not present. See that all screw pins holding gears to shafts are tight. Wipe off any condensed moisture which might have accumulated on the mechanism. Before applying the lubricant see that all parts are clean.

Oil and grease of the type mentioned above and in the quantities indicated below should be applied to the following points.

All Shaft Bearings 1 drop of oil each
Damper Gear Train *NH66 grease
1 drop of oil each bearing
Stop Screw & Bearings 3 drops distributed uniformly over screw
Miter Gears, Worm Wheels and Worms *NH66 grease

* Where NH66 grease is specified, Navy Grade 2, under NDS-14-L-3 (Std. Stock No. 14-L-125) may be used. A small amount should be spread evenly over the gear teeth or the bearing surface.

Wipe off any excess oil and grease which has run over surfaces not requiring lubrication.

To replace the dial lamp (55), the dial (71) should be rotated to the zero position. Remove the cover (9) and the three screws (49) holding the



18
 
dial oh the mounting disc. Renew the lamp and replace the dial on the mounting disc making sure the zero mark is directly under the dial pointer (41). When replacing speed transmitter dials the zero mark should be placed as directed above.

After removal of the mechanism from the case and before replacement, remove any chips or dirt and make sure that the inside of the case is dry. Before replacing the mechanism in the case, rotate the dial and generator by placing a screw driver in the slot in the main drive shaft to check for freedom of the moving parts.

4. DUMMY LOG DISTANCE TRANSMITTER, DRAWING #V-40256

The Distance Transmitter case should be opened every three months for inspection and lubrication according to instructions given in this paragraph. Remove the cover bolts (90), the cover (89). Proper operation of the Distance Transmitter depends upon freedom from excessive friction; all moving parts must be examined for such indications. All electrical contacts should be carefully cleaned with crocus cloth at the time of inspection and lubricating.

Particular care must be taken that the heart-shaped cam (117) and the stop support (144) are free to turn on brush ring shaft (130) so that the slightest displacement of the cam arm roller (76) from the law point of the heart-shaped cam (117) will cause a contact to be made between the contacts (141) and contacts (139) on the contact arm assembly (79, 131, 139).

Oil and grease of the grade mentioned previously in this section should be used for lubricating the Distance Transmitter. Quantities indicated below shall be applied to the following points:

Cam and stop support arm bearing (117) 1 drop
Cam disc, arm and roller bearings (11) 1 drop
All gears in each gear train *NH66 grease
Bearings, reversible motor (15) fill each bearing cap with oil
Miter gears on roller disc shaft (88) *NH66 grease
Disc and roller (64, 49) 3 drops applied to the surface of disc and roller spread uniformly with finger
Synchronous motor (41) Remove round head screws in motor case and fill each oil hole
Synchronous motor and disc carriage slide rods (157, 158) 3 drops distributed uniformly
Roller shaft ball-bearings (62) 1 drop each bearing


19
 
Differential assembly (43,57,42,71,72) *NH66 grease
1 drop of oil each pivot bearing
Rheostat shaft bearing *NH66 grease
Follow-up motor pinion (86) *NH66 grease
Reversible motor pinion and worms (40,150) *NH66 grease

* Where NH66 grease is specified, Navy Grade 2, under NDS-14-L-3 (Std. Stock No. 14-L-125) may be used. A small amount should be spread evenly over the gear teeth or the bearing surface.

In addition to the above points, a drop of oil should be applied to each gear bearing and all shaft bearings when possible. In all cases, any excess oil, grease, dirt and chips which have accumulated since the previous lubrication must be removed.

Parts which have been removed from the base plate for disassembly and repair may be washed in a solvent. Before replacing the parts on the base plate, all solvent must be cleaned off and the parts lubricated according to the above instructions.

For lubrication of the ball bearings in the self-synchronous generators and the motor refer to Section VI, describing these units in detail.

Place the cover on the case with the ventilating covers on the top.

5. REPLACING GEARS AND SHAFTS CONTAINING SCREW PINS

Each gear is held on its respective shaft by a screw pin. The screw pin consists of a straight portion and a threaded section concentric with it. It is screwed into place and will not be loosened by vibration.

Should it become necessary to replace any shaft in either instrument, the gear must be placed on the shaft and held in position. A pin hole must be drilled through the shaft .001 inch larger than the pin and concentric with the threaded screw pin hole in the gear hub. If the pin hole and the threads are not concentric, trouble will be encountered in inserting the screw pin into the hub. It is suggested that a drill jig be used.

Such a drill jig may be made by placing a piece of brass in a lathe and threading it with #5-40 threads 1/2 inch long. Drill a hole through the center of the threaded piece concentric with the threads, and just large enough to accommodate the pin hole drill. Leave enough stock on one end of the threads to form a head, which should be slotted for a screw driver.

The hub of each gear contains two #5-40 threaded setscrew holes. Place the gear on the shaft in the correct position. Insert a setscrew in one hole in the hub and tighten it against the shaft enough to hold the gear firmly in place. Insert the drill jig in the other setscrew hole and drill the pin hole through the shaft. A drill jig similar to the one described above is included in the spare parts box and is to be used when drilling any shaft for a screw pin.



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V. TESTING AND ADJUSTING

1. GENERAL

At the time of regular inspection and lubrication the Dummy Log System should be checked to determine whether the Distance Transmitter speed output in revolutions per minute is accurate over the full speed range.

With the system energized, set the speed transmitter dial to two knots and check against the distance indications at the Dead Reckoning Analyzer or the Dead Reckoning Tracer. Speed output should also be checked at three other points between the two knot indication and the highest dial reading; i.e., 25 or 40 knots. The speed output should not vary more than ± 1.2 R.P.M.

In the following paragraphs testing and adjusting the various units in the Speed Transmitter and Distance Transmitter are discussed in detail.

2. DUMMY LOG SPEED TRANSMITTER, DRAWING #V-40255

All adjustments necessary for free and easy operation of the mechanism are made at the factory before shipment. The transmitting generator (1) has been set to the electrical zero position and the worm wheel (79) pinned to the generator shaft when the stop collar (28) is stopped by the pin (77) at the front end of its travel. When the stop collar (28) is in this position, the zero mark on the dial (71) is set directly under the dial pointer (41). The three mounting holes in the dial are slotted to allow the dial to be shifted slightly.

Should the generator (1) and worm wheel (79) be removed from the brackets (34) for repair, they must be replaced in exactly the same position. Before removing the generator rotate the speed dial (71) to the zero speed setting. Note the two markings (scribed lines) on the generator case and the inside of the brackets (34). These marks must be directly in line. Also, note the mark on the generator shaft and the two marks on the generator worm wheel (79). The mark on the generator shaft is in line with the marks on the generator case and the bracket (34) when the generator is at electrical zero. The two marks on the generator worm wheel (79) denote the five teeth of the worm wheel which mesh with the worm (29) when the stop collar (28) is stopped by the pin (77). When so set, the worm wheel (79) is pinned to the generator shaft by a screw pin.

If these marks are not aligned exactly when the parts are reassembled, it can be seen that the electrical zero setting of the generator, and the zero speed indication on the dial will be out of phase.

Should it be necessary to install a new transmitting generator (1) the marks on generator case and shaft must be aligned with the mark on the generator bracket (34) as described in the above paragraph. Then connect the five leads of the generator across the 115 v. supply circuit as shown in the connection diagram on sheet 1, of the drawing #V-40255. Energize the motor allowing the rotor shaft to assume the electrical zero position.

Place the worm wheel (79) on the generator shaft meshing it with the driving worm (29). Place a drill jig in the screw pinhole in the hub of the worm



21
 
wheel (79), and tighten it against the shaft of the generator. Make sure the worm and worm wheel do not bind. Drill the hole through the generator shaft for the screw pin. Making this jig and drilling the hole was suggested and described under "Maintenance", (Section IV paragraph 5). Should a new worm wheel (79) be installed, the five teeth meshing with the worm (29) when the dial is in the zero position should be scribed on the gear after assembly.

Also, note the two identification marks on the worm wheel (46) of the dial mounting disc (45). These marks identify the five teeth of this worm wheel (46) which mesh with the driving worm (19) when the speed dial is set to zero. Should this worm wheel have to be removed for repair or replacement, it must be reassembled in the same position.

3. DUMMY LOG DISTANCE TRANSMITTER, DRAWING #V-40256

3-1 The Receiving Motor: The Distance Transmitter is so designed and adjusted, that when the self-synchronous receiving motor (1) is in the electrical zero position the roller (49) is in the center of the rotating disc (64) and receives no motion from the disc. Should it be necessary to replace the receiving motor (1), the rotor must be set to the electrical zero position as described in Section VI paragraph 5.

At the same time a preliminary setting between disc (64) and roller (49) must be made so that the roller is in the center of the disc. Loosen the setscrew in the hub of the bevel gear (80), withdraw the shaft and pinion (193) enough to disengage the pinion (193) and the idler gear (10). Rotate the idler gear (10) by hand until the roller (49) is directly in the center of the disc (64). Replace the pinion (193) to mesh with the idler gear (10) and the end of the pinion shaft to engage the bevel gear (80). Tighten the screw pin in the hub of the bevel gear (80).

The receiving motor (1) should then be properly connected to the speed transmitter generator and the distance transmitter generator to the Dead Reckoning Analyzer. Energize the system and rotate the Speed Transmitter from 2 knot speed indication to half scale (12.5 or 20 knots) approaching the setting slowly, being careful not to over run the half scale mark. Measure the speed of the receiving motor in the Dead Reckoning Analyzer. Rotate the Speed Transmitter back to the 2 knot speed indication and measure the speed of the receiving motor in the Dead Reckoning Analyzer.

Now adjust the position of the receiving motor (1) in the Distance Transmitter by loosening the three clamping bolts (5). Rotate the motor housing by hand until the setting error (R.P.M.) is the same when the speed transmitter dial is set to the 2 knot indication or half scale. The motor casing may have to be moved several times to have the error equal at each setting. This setting error must be within ± 1.2 R.P.M. of the speed indications corresponding to the settings used. When this setting error is equal, tighten the clamping bolts (5) holding the receiving motor in place.



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3-2 Setting Stop Switches: Connect the Distance Transmitter in circuit with the Speed Transmitter and set the speed transmitter dial to 24.6 knots for a 25 knot system or to 39.6 for the 40 knot system. At this time the Distance Transmitter will be rotating at approximately 150 or 240 R.P.M. With a small wrench, loosen the lock nut (82) on the trip screw (83) in the end of the synchronous motor carriage slide rod (157) and turn the screw until it presses against the micro-switch (19) button opening its contacts. Tighten the lock nut (82). Set the speed transmitter dial at a lower speed so that the stop-switch contacts will close and slowly turn the dial back toward the maximum speed indication checking to see that the switch functions properly at the dial setting noted above.

The stop-switch (19) in the synchronous motor (41) circuit and the switch (19) in the clockwise direction circuit of the reversible motor (15) should now be adjusted to open successively. The former should open the synchronous motor circuit between 0.4 and 0.8 knots and the latter should open the clockwise rotation circuit between 0 and 0.4 knots. Set the dial in the speed transmitter between 0.4 and 0.8 knots, loosen the lock nuts (23) in the trip arm (22) on the end of the slide rod (158), and adjust the bottom screw to open the bottom switch (19) at this dial setting.

Move the speed transmitter dial to between 0.4 and 0.8 knots and adjust the top screw (24) to open the top switch (19) at this dial setting. Rotate the Speed Transmitter to a higher speed and then back to check the setting of these switches. It is important that the rotation of the synchronous motor (41) stop before the reversible motor (15) stops.

3-3 Adjusting Cam and Brush Ring Assembly: The switch contacts (141, 139) controlling the direction of rotation of the reversible motor (15), should have a clearance of about .008 inch which is obtained by turning the contact adjusting screws (139). The brushes should make firm contact with the brush rings.

3-4 Reversible Motor (15): The gear train consisting of the gears (193, 10, 80, 75, 40) between the reversible motor and the jack screw (159) should have a minimum amount of backlash. An instrument designed for 25 knots speed output contains gear (60) and pinion (75) in the reversible motor gear train. In a 40 knot instrument, two miter gears, identical to the gears (88) on the synchronous motor and roller disc shafts, are substituted for gear (80) and pinion (75). Substituting gears (88) for gears (75, 80) and adjusting the trip screw (83) in the end of the slide rod (157) is the only mechanical difference between a 25 knot Distance Transmitter and one with 40 knot speed output.

3-5 Synchronous Motor and Carriage: The synchronous motor (41) and carriage assembly must slide freely in the slide rod bushings (94) in the roller mounting bracket (48). If for any reason the carriage (28) or the jack-screw (159) are removed from the bracket (48), they must not bind at any point when reassembled. Binding of the parts will stall the reversible motor (15). End play between the jack-screw drive gear hub (73) and the jack-screw bushing (68) in bracket (48) should be between .003 and .006 inch. This end play between the two members can be removed by placing a shim washer of the necessary thickness on the jack-screw shaft between the gear hub and the flange of the bushing (68).



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The 115 volt 60 cycle single-phase power supply to the synchronous motor must not vary more than plus or minus 1/10 of 1 percent. Should the variation be greater, the speed output of the distance transmitting generator will be affected proportionally.

Wearing of the roller from the original diameter of .627 inch to one smaller will increase the speed output of the distance transmitting generator. Should the roller (49) wear to .620 inch, it should be replaced, as the R.P.M. output of the generator will be in error in an amount greater than the tolerance specified. A weak or broken roller disc spring (69) will cause too little friction between the roller disc (64) and roller (49). This will cause slipping between the disc and roller. Side play in the roller disc shaft (65) will cause the speed out of the generator (162) to vary more than the allowed tolerance.

The roller disc (64) is ground and lapped on both sides; if one side should became worn or rough, it should be turned over and the other side used.

3-6 Differential, Follow-Up Motor and Rheostat: The differential case (71, 42, 72) should turn freely on the hubs of the sun gears (43, 57). The planetary pinions (42) and sun gears should not bind.

Proper operation of the follow-up motor (56) and the control rheostat (45) can be checked while the instrument is in operation. The shaft of the transmitting generator should be stopped abruptly, which will rotate the rheostat contact arm to its extreme position. Release the shaft suddenly allowing the contact arm to swing back. The contact arm must assume its proper position in not more than 3 cycles of oscillation. Excessive oscillation of the rheostat will indicate a variable load on the type "B" generator or the Dead Reckoning Analyzer. The contact arm should press against the coil of the rheostat firmly. If this pressure is too little, the contact arm will oscillate excessively. Should the pressure be too great it will stall the roller shaft.

3-7 The Distance Transmitter Generator: This generator (162) is not set to electrical zero as it is in continuous rotation. Under proper operation the speed output between 6 to 1E0 or 6 to 240 R.P.M. shall not vary more than plus or minus 1.2 R.P.M. measured at the Dead Reckoning Analyzer.

Should the Distance Transmitter be disassembled for repairs, the speed output of the generator (162) should be checked at 4 different positions throughout the speed range, after assembling. The lowest speed shall not be less than 12 R.P.M., the equivalent of 2 knots.

To set and adjust the Distance Transmitter after reassembling, proceed as directed in paragraph 3-1 of this section.

For details of self-synchronous generators and motors refer to Section VI.



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VI. SELF-SYNCHRONOUS GENERATORS AND MOTORS

1. GENERAL DESCRIPTION

Self-synchronous units consist primarily of the following parts: Stator Assembly, Rotor Assembly, Front and Rear End Covers, Terminal Block Assembly, and Terminal Block Cover.

The stator consists of special magnetic steel laminations clamped together inside a steel shell by the spun-over ends and two field coils mounted on these Laminations. The coils are softened by heating and then formed to fit over pins. The leads from coils to terminal block pass through insulating bushings in the rear end cap.

The rotor consists of special magnetic steel laminations clamped together on the shaft by a collar. A three phase winding is distributed in the rotor slots and a molded collector ring assembly for the rotor leads is fitted onto the end of the shaft. The complete rotor assembly is statically balanced.

The terminal block assembly consists of a molded bakelite housing, two sets of side contact springs for two of the rotor leads, an end contact spring for the third rotor lead, brass plates for mounting the contact springs, bakelite plates for insulation and cover, and five external lead wires.

Special open-type ball bearings are mounted in the end caps for supporting the rotor. Dust guards are placed in front of the bearings. Bronze shims behind the bearings align the rotor and give the proper end play.

2. THEORY OF OPERATION

The single-phase stator windings of the transmitter generator and all receiving motors to be operated in circuit with the generator are connected to the 115 volt 50 cycle power circuit. The three-phase rotor windings of all these units are connected together electrically.

When the power circuit is closed, an A.C. voltage is impressed upon the connected stator windings. The single-phase current in the stator (primary circuit) of each unit induces voltages which vary with the position of the rotor in relation to the stator.

If the angular rotor positions of the receiving motors are not the same as the angular rotor position of the transmitting generator, the voltage induced in the three phases of the receiver rotors will not be equal to and balance the induced voltage in the corresponding three phases of the transmitter rotor. Due to the unbalanced induced voltages, currents will flow in these circuits, creating a torque between the rotor and stator of each receiver unit, which changes the angular rotor positions of the receiver motors to agree with the angular position of the transmitter rotor.



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When the transmitter rotor is manually operated and turned, and the rotors of the receiver motors are free to turn, the rotors of the receiver motors will follow the transmitter rotor at the same speed, and in the same direction. When the transmitter rotor is held in one position, the receiver rotors will be in exact agreement.

3. MAINTENANCE

Trouble indications listed below are in reference to the position or rotation of the receiving motor or the Distance Transmitter not functioning correctly. Such trouble will be shown by the speed output of the distance transmitter being in error. If the trouble is not localized in the receiving motor, the transmitting generators should be checked for electrical and mechanical defects.

Oscillating motion over a portion of the total (360 degrees) operating angle:-One of the rotor circuits may .be open due to a burned out or open coil, or to a brush or collector ring being corroded and not making proper contact.

False position of the receiving motor in the distance transmitter:- The rotor of the one receiving motor may be locked and not free to revolve. When this condition exists, there is likely to be a pronounced hum in the instrument.

Erratic movement of the receiving motor rotor sometimes making several revolutions and stopping at either of two positions, 180° apart:--Check for an open field winding in the stator coils.

Rotation opposite to the direction of the transmitting generator:-Two leads of the three coil rotor winding should be reversed (i.e., R-1 and R-3).

Definite wrong position varying somewhat as the transmitter rotor is rotated:-Check for a short circuit in one of the rotors.

Indication 180° away from correct position:-Check for an open feed wire to the speed transmitter generator.

Irregular motion:--The rotor bearings are probably corroded or dirty and should be cleaned and oiled.

No movement of any kind:-Check for power supply and open motor circuits.

4. DISASSEMBLY

Disassembly for inspection and replacement of various parts is described below:

Rotor: Remove the shaft end cap by loosening the four screws and the rear terminal block cover by loosening one screw. Care should be taken not



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to damage the brush contact springs or collector rings on the end of the shaft when a rotor is being removed or replaced through the shaft end of the stator. The rotor should have approximately .010 inch end play when the end caps are fastened in place. This is obtained by the use of shims back of both ball bearings. Any tendency to hum when the unit is assembled and the stator coils are energized is eliminated by varying the quantity of shims at both ends.

Stator Coils: Remove the shaft end cap, rotor, rear cover, terminal cover plate, terminal block assembly, and the rear end cap. When replacing the stator coils, they must be softened by heating before they can be removed. New coils must also be softened and then formed to fit the lamination assembly.

Ball Bearings: For access to the shaft end bearing, remove the shaft end cap and rotor. The inner bearing race makes a snug fit on the rotor Shaft and the outer race a light push fit on .the shaft end cover. The inner race of the bearing may be lifted off the shaft, while the outer race must be pressed out of the cover. To remove the rear bearing, take off the terminal cover, the terminal block and push the outer race from the cap by pushing pins through the holes in the rear end cap. When replacing bearings, clean them carefully with light instrument lubricating oil (heated, if necessary). Handle the bearings with tweezers; hot with the hands. Relubricate with Norma-Hoffmann grease #66, Navy Grade 2, under NDS-14-L-3 (Std. Stock No. 14-L-125). New ball bearings should have all anti-rust grease removed.

Contact Parts: Remove rear terminal block cover and plate.

5. SETTING THE SELF-SYNCHRONOUS GENERATOR OR MOTOR TO ELECTRICAL ZERO

Connect the stator lead, S-2, and the rotor leads, R-1 and R-3, to one side of the 115 volt 60 cycle single-phase supply circuit. To the other side of the circuit, connect the stator lead, S-1, and the rotor lead, R-2. Close the supply circuit and allow the rotor of the unit to come to rest in the electrical zero position. Tighten any parts to their respective shaft in proper relation to the balance of the mechanism the unit is assembled with.

Keep the power on no longer than necessary, as it will cause overheating of the motor windings. Proper connections to the supply circuit is shown on both assembly drawings V-40255 and V-40256 of the Speed Transmitter and the Distance Transmitter respectively.

 

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