Copy 3 ,DE PARTMENT FIELD MANUAL

'i l

- CSERVICE

OF SEACOASTSEARCHLIGHT

DSEMINATtON OF RESTRICTED MATTER

ISSEMINATION OF .i ade or poliston to

N eo T of l ctItd sole o ¥ by vi:rto o .o e o. ti s 0. s Oo

Ientrusted ony to a regraph 23bs AR 380'

s MarU S 1944)

WAR DEPARTMENT * 30 AUGUST 1945

WAR DEPARTMENT FIELD MANUAL

FM 4-29

SERVICE

OF SEACOAST

SEARCHLIGHT

WAR DEPARTMENT a 30 AUGUST 1945

I MDISSEMINATION OF RESTRICTEDATTER. No person is entitled solely by virtue of his

grade or position to knowledge or possession of classifiedmatter. Such matter is entrusted only to those individualswhose official duties require such knowledge or possession.

(See also paragraph 23b, AR 380-5, 15 March 1944.)

Arnmy Field Printing Plant, CAS

Fort Monroe, Va.-1945

WAR DEPARTMENTWASHINGTON 25, D.C., 30 August 1945

FM 4-29, Service of Seacoast Searchlight, is pub-lished for the information and guidance of all con-cerned.

[AG 300.7 (27 Jun 45)1

BY ORDER OF THE SECRETARY OF WAR:

OFFICIAL: G. C. MARSHALLEDWARD F. WITSELL Chief of StaffBrigadier GeneralActing The Adjutant General

DISTRIBUTION:

AAF (10); AGF(40); ASF(2); T of Opns(5);Arm & Sv Bd (1); Def Comd (5); Tech Sv 5 (5);HD(2); R 4(2); Bn 4(2); C 4(2), except T/O& E 4-68 (15); 4-77 (5); 4-156(10). SpecialDistribution.

For explanation of distribution formula, seeFM 21-6.

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CONTENTS

Paragraphs Page

CHAPTER 1. GENERAL ........... ... 1-4 1

CHAPTER 2. ORGANIZATION ANDEQUIPMENT.

Section I. Organization ............ 5-8 3II. Equipment ............ .. 9-16 4

CHAPTER 3. EMPLOYMENT OF SEA-COAST SEARCH-LIGHTS ............... 17-18 20

CHAPTER 4. DUTIES OF PERSONNEL 19-29 26

CHAPTER 5. NOTES ON SERVICE OFTHE SEARCHLIGHT.

Section I. Operation .......... .. 30-34 . 30II. Spread-beam lenses ...... 35-36 39

III. Power plant operation ... 37-45 44IV. Safety precautions ...... 46 47

CHAPTER 6. FIELD OPERATIONS ... 47-50 49

CHAPTER 7. CARE AND ADJ U S T -MENT OF MATERIEL 51-53 56

CHAPTER 8. DESTRUCTION OFSEARCHLIGHTEQUIPMENT .......... 54-63 57

APPENDIX I. LIST OF REFERENCES ....... 61

II. TECHNICAL DATA .......... 63

III. DRILL TABLE ............... 69

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CHAPTER 1

GENERAL

1. SCOPE. This manual is a guide for the batterycommanders, platoon commanders, section leaders,and light commanders of seacoast artillery search-light units in harbor defenses or in the field in train-ing searchlight squads in the orderly, efficient opera-tion of seacoast searchlights. It covers organizationand equipment, searchlight employment, duties ofpersonnel, service of the searchlight, field operations,care and adjustment of materiel, and destruction ofequipment.

2. REFERENCES. This manual is intended for usein conjunction with existing field and technicalmanuals on searchlights and associated subjects.Appropriate manuals are listed in appendix I.

3. DEFINITIONS. The following is a brief glossaryof terms used in searchlight operation:'

Barrier light. A searchlight used to place an un-moving beam across a channel or a harbor entrance.

Control station. Element of searchlight equipmentused to move the searchlight in azimuth and elevationby distant electric control.

Designation. Each searchlight is designated forcommand purposes by the number of the position itoccupies. For example, the command TWO, COVER FOURorders the searchlight designated as No. 2 to cover

'For definitions of military terms not contained in thismanual, see TM 20-205, and for a complete list of availabletraining publications, see FM 21-6.

the target illumhi_ hlight designatedas No. 4.

Detector. A radar set (SCR-268 or AN/TPL-1)used for searchlight control. This set is not usuallyavailable to seacoast artillery searchlight units.

Distant electric control (DEC). Control of thesearchlight from a flank station located not morethan 500 feet from the searchlight.

Extended hand controller. Device used to operatethe searchlight manually (used in the event of failureof distant electric control).

Illuminating light. A searchlight used to illumi-nate hostile vessels so that they may be tracked andfired on.

Normal beam. The 11/4° beam projected by a prop-erly adjusted searchlight when spread-beam equip-ment is not used.

Searching light. A searchlight used to searchwater areas for the purpose of detecting hostilevessels.

Searchlight set. This term is used to designateone searchlight and the associated equipment re-quired to operate it (control station, power plant,etc.).

Spread beam. The 10° beam obtainable by the useof spread-beam lenses.

STAND BY. The command at which the designatedlight is kept ready to go into action immediately. Ifthe position of the target is known, the light is kepttrained on it.

4. COMMANDS. Commands used in searchlightoperation and control are listed in FM 4-5.

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CHAPTER g2

ORGANIZATION AND EQUIPMENT

Section I. ORGANIZATION

5. GENERAL. Each seacoast searchlight is operatedby a squad comprising a light commander, a controlstation operator, a power plant operator, and a search-light operator. Larger searchlight units consist of 'anumber of squads augmented by necessary adminis-trative and repair personnel, organized into sections,platoons, and, in the case of T/O&E 4-68, into a bat-tery. In mobile organizations, the searchlight squadalso includes truck drivers and machine gunners.

6. HARBOR DEFENSE SEARCHLIGHTS. Seacoastsearchlights in a harbor defense are operated by theseacoast platoon of the searchlight battery (T/O&E4-68).. This platoon comprises four to twelve search-light squads grouped in two, three, or four sections.Each section operates two or three searchlights.Each platoon includes communications personnel anda searchlight electrician.

7. SEARCHLIGHTS FOR ANTIMOTOR TORPEDOBOAT DEFENSE. Each 90-mm AMTB battery(T/O&E 4-77) is assigned one searchlight and per-sonnel comprising one searchlight squad to man it.

8. SEARCHLIGHTS WITH MOBILE ARTILLERY.A searchlight platoon is included in the headquartersbattery of each 155-mm gun battalion (T/O&E 4-156).This platoon consists. of a platoon headquarters andtwo sections of four searchlight squads each and in-

3

eludes a searchlight electr:ician, truck drivers, andmachine gunners.

Section II. EQUIPMENT

9. GENERAL. a. The searchlight sets authorizedfor issue to seacoast artillery units include the 60-inch mobile searchlight, the distant electric controlstation, the extended hand controller, the power

1. Arc switch handle. 8. Junction box.2. Elevation control box. 9. Azimuth amplidyne motor-3. Lamp mechanism box. generator.

4. VentiigDrum. fan housing. 10. Elevation amplidyne motor-5. Ventilating fan housing.nerator.6. Elevation control trans- ge

former. 3.1. Azimuth circle.7. Elevation amplifier box. 12. Azimuth control box.

Figure 1. General Electric searchlight M1942 (with spread-beam lenses).

4

plant, and interconnecting cables. Transportation isauthorized separately on T/O&E.

b. Searchlight equipment now in service includescomponents of two types and several models. Thetypes are General Electric and Sperry, the names ofthe manufacturers producing the equipment. Eachmanufacturer produced a new model each year be-tween 1939 and 1942, designated by the number ofthe year (M1940, M1941, etc.), and each manufacturer

1. Azimuth drive housing. 7. Elevation drive housing.2. Arc switch box. 8. Extended hand controller3. Meter box. socket.4. Lamp operating mechanism

box. 9. Elevation amplifier housing.5. Blower hood. 10. Azimuth motor-amplidyne6. Drum, generator.

Figure 2. Sperry searchlight M1942 (operating position).

also produced two special models (M1941A andM1942A). Some earlier Sperry models, dating asearly as 1934, may still be in service. All of theseitems of equipment were originally designed for anti-aircraft use but all of them. can readily be used forseacoast artillery missions.

c. When issued, searchlight sets usually consist ofelements of the same type and model. However, withthe exception of searchlights M1942 and M1942A,equipments made by the same manufacturer in dif-ferent years. differ so little as to be widely inter-

1. A-frame. 6. Azimuth scale.2. Elevation control box. 7. Chassis.3. Beam-spread handwheel. 8. Azimuth control box.4. Elevation amplifier box. 9. Elevation amplidyne gen-5. Azimuth amplidyne genera- erator.

tor. 10. Elevation stowing spring.

Figure 3. General Electric searchlight M1942 (transporta-tion position).

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changeable. Control stations, extended hand con-trollers, and control cables of Sperry searchlightsM1939, M1940, M1941, and M1941A may be used inany combination to operate any Sperry searchlightof any of those models. Control stations, extendedhand controllers, and control cables of General Elec-tric searchlights M1940, M1941, and M1941A may beused in any combination to' operate any GeneralElectric searchlight of any of those models. GeneralElectric and Sperry power equipment (power plants

1. Arc switch box. 8. Steering bar.2. Meter box. 9. Chassis.3. Beam-spread handwheel. 10. Azimuth drive housing.4. Elevation drive housing.5. Extended hand controller 11. Elevation amplidyne gen-

socket. erator.6. Elevation amplifier housing. 12. E 1 e v a t o n transportation7. A-frames. lock bars.

Figure 4. Sperry searchlight M1942 (transportationposition). S

and power cables) for 60-inch searchlights can beused interchangeably with either type of search-light of any model since 1936. Because of a modifi-cation in azimuth and elevation drive equipment,1942 models of either type cannot be used withcontrol equipment of earlier models, but all com-ponents of General Electric and Sperry 1942 equip-ment are interchangeable except for the extendedhand controllers.

d. This manual includes summarized descriptivedata on the 1942 models of both types (figs. 1 to 4).For more complete information, appropriate techni-cal manuals should be consulted. (See references,app. I.)

10. SEARCHLIGHTS. a. Components. The search-light consists of the chassis, the base, the turntable(mounting the trunnion arms), and the drum. Eachof these components is discussed briefly below.

(1) Chassis. The chassis, carried on four rubber-tired wheels, is primarily a frame for mounting thesearchlight. Four jacks, one at each corner of theframe, support the equipment during operation andprovide a means for leveling the chassis. A towingbar is provided for use when it is necessary to movethe searchlight by hand. (The searchlight shouldnot be towed by truck except when mounted in thesearchlight trailer.) The following electrical andmechanical elements of the equipment are mountedon the chassis: the dyna:motor, which converts aportion of the d.c. supply into power for the a.c. ele-ments of the equipment; the junction box, whichcontains receptacles for interconnecting cables (par.14); a ballast resistor, which compensates for varyinglengths of power cable; and elements of the azimuthcontrol system (varying in detail with differentsearchlight models).

(2) Base. The base assembly has two functions:to support the turntable and to transfer arc and con-trol voltages to other elements of the searchlightduring operation. A central pivot and heavy-duty

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annular ball bearings support the turntable. A slip-ring subassembly transmits the required voltagesfrom the junction box to brushes mounted on theturntable. An azimuth scale encircles the base. (Asissued, searchlight azimuth circles are graduated inmils. Circles graduated in degrees have been dis-tributed to some harbor defenses. Similar scales forall seacoast searchlights now in service will beissued.) Some elements of the azimuth control anddrive systems are mounted on the base (varying indetail with different searchlight models).

(3) Turntable (trunnion arms). The turntablesupports the drum at the trunnions and containsgearing which meshes with other gears on the baseand the drum to drive the searchlight in azimuth andelevation. All elevation control and drive mech-anisms are mounted on the trunnion arms assembly.The arc voltmeter, the arc ammeter, and the zeroreading meters are also mounted on the trunnionarms.

(4) Drum. The drum is a large cylinder of alumi-num alloy (or sheet steel, in some later models),consisting of front and rear sections joined to form aunit. It houses the lamp and the mirror. The lampconsists of a high-intensity carbon arc and the neces-sary electrical and mechanical connections to main-tain a high current flow through the carbons and tokeep the gap separating them at a constant value.The composition of the carbons is such that the pas-sage of a high current through them and across thearc causes a small, brightly burning globule of in-candescent gas to form at the tip of the positive car-bon. This luminous ball of vapor is the light sourcefor the searchlight. The 60-inch parabolic mirrorfocuses light rays from the arc into a narrow (104° )

beam having an intensity of 800,000,000 candlepower.A ventilating fan, mounted on top of the drum, coolsthe lamp elements and exhaust vapors given off bythe arc, preventing discoloration of the mirror or theglass drum doors. Other control elements mounted

9

on the outside of the drum include: the lamp controlmechanism, which controls operation of the arc(par. 31); the peep sights and ground-glass finderused to view the arc during operation; the elevationrack, which engages the elevation drive gearing onthe right trunnion arm; and a peep sight, used inorientation (mounted on the left side of the drum).The recarboning lamp, mounted inside the drum,provides light when it is necessary to change carbonsduring operation. An elevation scale is mounted onthe elevation rack.

b. Spread-beam modification. (1) The n o r m a 1(11/4° ) beam of the searchlight is unsatisfactory fortracking maneuverable, h:igh-speed targets (such as

Figure 5. Searchlight with spread-beam lenses (normal-beam position).

10

motor torpedo boats) at short ranges. Most mobilesearchlights now in service have been modified topermit spreading the beam to a width of 15 ° by de-focusing the light. (See FM 44-6 and FM 44-75.)However, this modification is not considered suitablefor seacoast searchlights, and a special modificationhas been authorized for use by seacoast artilleryunits.

(2) The seacoast artillery spread-beam equipmentconsists of four lenses mounted in front of the glassdoor of the drum (figs. 5 and 6). When these lensesare locked in the open position (fig. 5), the searchlightprojects the normal beam. When the lenses are

Figure 6. Searchlight with spread-beam lenses (spread-beam position).

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closed (fig. 6), the beam is spread to 10 ° in the hori-zontal dimension but the vertical dimension of thebeam is virtually unchanged. (The convolutions ofthe lens must be vertical to achieve this effect.)

(3) The spread-beam modification kit for use withSperry searchlights later than model 1934 and Gen-eral Electric searchlights later than model 1940 maybe obtained by requisition through channels to theChief of Engineers. The kit includes the following:six 24-inch molded glass lenses (four for use, two forspares), five of them complete with lens-holdingrings; hinge-type mounting brackets; a counter-weight assembly (used to adjust the balance of thedrum after installation of the lenses); and necessaryinstallation hardware. Instructions for installing themodification on any standard light accompany eachkit. (Note. In addition to the adjustments describedin the installation manual, the counterweight assem-bly should also be adjusted to compensate for thecondition in which two of the lenses are open andthe other two are closed.)

11. CONTROL STATIONS. It is difficult for an ob-server stationed at or near the searchlight to tracka target illuminated by the beam. In order to do so,he must observe the target through the searchlightbeam. The range at which he is effectively able todo so is considerably reduced by the effect of illumi-nated particles in his line of sight. The farther theobserver can be displaced from the light (consistentwith technical considerations of control), the betterare the results which can be obtained. The distantelectric control station is a solution to this problem.Equipment now in use permits visual tracking ofan illuminated target from a station 300 to 500 feetdistant from the searchlight. Angular movement ofthe control station handwheels is transmitted elec-trically to the searchlight and transformed intomechanical energy causing a corresponding angularmovement of the searchlight. When the two elements

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are properly oriented and synchronized, the search-light automatically follows a target held in the fieldof the observer's binocular at the control station.

a. Components. The three principal componentsof the control station are the tripod, the control unit,and the binocular mount. Each is described brieflybelow.

(1) Tripod. The main function of the tripod is toprovide support for the other components of thecontrol station. Tripod equipment includes jack-screws for leveling the station. Sperry tripodsinclude a receptacle for the control cable, and sliprings, brushes, and contacts for the transmission ofelectrical energy from the fixed base to the rotatingcontrol unit. The General Electric tripod containsno electrical equipment.

(2) Control unit (controller). Four handwheelsand two zero-reading meters are the outstandingfeatures of the control unit. Of these, only the twoobserver's handwheels (fig. 7) are used in normalseacoast operation. The other handwheels and thezero-reading meters are used only when a radar de-tector is a part of the searchlight system (except asnoted in par. 33). Movement of the observer's azi-muth handwheel rotates the control unit (a selectorpermits choice of two speeds of control unit rotation)and generates a control voltage which is transmittedto the searchlight. Movement of the observer's ele-vation handwheel moves the binocular mount inelevation and generates a control voltage which istransmitted to the searchlight. The unit is equippedwith slip clutches which permit slewing of the con-trol unit in azimuth independently of the search-light. The General Electric controller is set on afixed base which contains a receptacle for connectingthe control cable and contacts through which poweris transmitted to the searchlight.

(3) Binocular mount. The binocular mount sup-ports the observer's binocular (or open sight) at aheight which can be adjusted to conform to the

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1. Daylight sight. 7. Azimuth circle.2. Binocular. 8. Tripod leg.3. Elevation linkage. 9. Leveling Jack.4. Binocular mount adjustment 10. Carrying handle.

handles.5. Elevation zero reader hand- 11. Azimuth zero reader hand-

wheel. wheel.6. Observer's elevation hand- 12. Observer's azimuth hand-

wheel. wheel.

Figure 7. Control station.

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height of the observer. A system of gearing andlinkage permits movement in elevation correspond-ing to the movement of the searchlight. Slip clutchesand control handles permit slewing of the binocularindependently of the control unit and the searchlight.This adjustment compensates for any error whichmay be introduced by parallax between the controlstation and the searchlight. This component is notessential for seacoast searchlight operation.

b. Modifications. Control stations as issued haveno azimuth scales. Azimuth circles graduated indegrees are issued separately for control stationsused by Coast Artillery units (fig. 7). Pending re-ceipt of these scales, azimuth circles must be im-provised.

12. EXTENDED HAND CONTROLLER. The ex-tended hand controller is a device for driving thesearchlight manually in elevation and azimuth inthe event that the distant electric control systemfails. It consists of an outer sleeve, approximately10 feet long, and a concentric shaft terminating in ahandwheel. The sleeve is inserted in a socket onone of the trunnion arms (the left trunnion arm ofthe Sperry M1942 searchlight; the right trunnion armon the General Electric 1942 model) and clampedinto place. A key on the concentric shaft engagesthe elevation gearing on the searchlight so that thesearchlight can be moved in elevation by rotation ofthe handwheel on the extended hand controller. Thesleeve is used as a lever to move the searchlight inazimuth. (Azimuth and elevation clutches must bemanipulated to disengage power drive gearing beforehand control may be used.) This system permitsemergency pointing of the searchlight and providessufficient displacement for the observer to reduceslightly the undesirable effects of observation throughthe searchlight beam.

13. POWER PLANT. The searchlight power plant(fig. 8) is a gasoline-engine-driven generator with a

15

rated output of approximately 160 amperes (d.c.) at100 volts. The control panel includes motor metersand controls similar to those on an automobile dash-board; a main power switch; a power ammeter; apower voltmeter; and a field rheostat used to controloutput current and voltage. Power plants of differentmodels vary considerably in detail but are sufficientlyalike in performance to be used interchangeably withany model since 1936 of either type of searchlight.

1. Side access doors. 3. Generator.2. Control panel. 4. Engine.

Figure 8. Power plant.

14. INTERCONNECTING CABLES. Three cablesare required to connect elements of the searchlightsystem. These are two power cables, one positiveand one negative, each 200 feet long, and a controlcable 300 or 500 feet long (depending on the equip-ment model being used). The power cables are

16

connected between the main power receptacles atthe power plant and the yellow-painted receptacleson the junction box at the searchlight. The 15-con-ductor control cable is connected from the receptacleon the tripod of the control station to the red-paintedreceptacle on the junction box at the searchlight.The blue receptacles on the searchlight junction box(there may be one or two, depending on the model)are not used in normal seacoast searchlight opera-tion. Later model searchlights have no color codingof receptacles, but construction of the plugs preventswrong connections.

15. TRANSPORTATION. A completely m o b i l esearchlight unit (AA) is equipped with two 21/2-toncargo trucks and a searchlight trailer M1 Head-quarters battery of the 155-mm gun battalion, whichis designated as semimobile, is authorized one 2Y-ton truck and one searchlight trailer for each twosearchlights. Each harbor defense is authorized onesearchlight trailer for such movement of search-lights as may be necessary.

a. The searchlight trailer M1 (figs. 9 and 10) is afour-wheel, pneumatic-tired tilting trailer with aload capacity of 4,000 pounds. It is equipped with ahand-operated winch used for loading the searchlightand with four turnbuckles which engage hold-downdevices on the searchlight chassis to lock it in placeduring transportation. Access doors in the front ofthe trailer permit reaching the front turnbuckles.It has hand brakes, used when the trailer is parked,and four-wheel electric brakes which can be oper-ated from the cab of the towing truck. A jumpercable provides power for the brakes and for tail andstop lights on the trailer. A breakaway chain setsthe brakes in the event that the trailer breaks loosefrom the towing truck.

b. The power plant is transported over smoothroads by towing behind a 2Y2-ton truck. Over badroads, it is advisable to load the power plant in a

17

searchlight trailer or a 21/2-ton truck if it is to betransported for a long distance. If the power plantis loaded in a vehicle, it must be securely chockedand wired in place.

16. SPARE PARTS. A complete list of organiza-tional spare parts for 1942 searchlights is containedin Army Service Forces catalogs ENG 7-S53 (Sperry)'and ENG 7-S55 (General Electric). These catalogsalso serve as authority for the requisition of replace-ment parts.

1. Blackout, stop, and taillight. 4. Access doors.2. Removable bows. 5. Turnbuckles.3. Corner jacks. 6. Winch chain.

7. Tailgate (ramp for loading).

Figure 9. Searchlight trailer Ml, tilted for loading.

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Figure 10. Searchlight trailer Ml, loaded (cover removed).

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CHAPTER 3

EMPLOYMENT OF SEACOAST SEARCHLIGHTS

17. SEACOAST ARTILLERY ROLE. a. Missions.Seacoast artillery searchlights are employed pri-marily as a surveillance aid for Coast Artillery bat-teries and associated beach defense detachments.Searchlights employed in this way are used to-

(1) Search water areas (searching lights).(2) Illuminate hostile naval vessels (illuminating

lights).(3) Place a barrier beam across a channel or other

confined approach to a defended area (barrier lights).These lights are used only in exceptional cases(FM 4-5).

(4) Illuminate or search beaches.b. Communications. A telephone net suitable for

use by both harbor defense units and mobile organi-zations is shown in figure 11. (This installation maybe modified to place the searchlight officer and thesearchlight switchboard in the radar station in situa-tions where this is practicable. However, it is offirst importance for the searchlight officer to have anuninterrupted view of the water area covered bysearchlights under his control.) The circuit fromthe searchlight switchboard to the telephones atsearchlight and controller should be operated as a"hot loop," that is, one or both of the telephonesshould be manned at all times except when the com-mand REST has been given. When the searchlightsquad is at rest, one ,or more members of the squadshould be near enough to the telephone at all timesto hear the ringing signal. When the tactical situa-tion requires that control of any searchlight or search-

20

lights be turned over to the commander of a firingbattery, the battery CP and the searchlight or search-lights should be connected through the searchlightswitchboard as indicated. This net may be readilymodified in situations requiring additional lines (asin the case of a 155-mm battalion operating as fourtwo-gun firing units). The searchlight officer's tele-phone may be eliminated (in this case the officerrelays his commands to the searchlight squadsthrough the telephone operator). The trunks be-tween command post switchboard and searchlightswitchboard may be eliminated if the two switch-boards are close enough together to permit direct oralrelay of intelligence between the two switchboards.Two or more searchlights may be connected on asingle line (in this case, searchlights sited to illumi-nate the field of fire of a particular battery or firingunit should be connected on the same line to facilitatesearchlight control by the battery commander). Ifnecessary, the battery searchlight control line may beconnected through the command post switchboard(in this case, trunks connecting the command postswitchboard and the searchlight switchboard willbe necessary).

c. Assignment and pickup of targets. When thesearchlight officer desires to illuminate a target lo-cated by surveillance radar or other means, he tele-phones a relocated azimuth (allowing for travelduring 20 seconds of dead time) to the searchlight orsearchlights best able to illuminate the area. If thetarget is not illuminated when the searchlight isturned on and is not detected in the 100 sector ofsearch (par. 33b), the searchlight officer gives theorders necessary to place the searchlight beam ontarget. He commands: RAISE (LOWER) if it is evi-dent that the range of the illuminated area is widelydifferent from the range of the target. If it is ap-parent that an error has been made in azimuth, hecommands: SEARCH RIGHT (LEFT). If one search-light of several assigned to a target picks it up, the

21

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searchlight officer commands: COVER, thus indicat-ing that the other lights are to cover the illuminatedtarget. If the nature of the error is doubtful, heorders one searchlight to search the area in whichthe target is believed to be. He directs at the othersearchlights the command: OUT, prior to the investi-gation of the error. When the target has been pickedup, the searchlights assigned to it track in accordancewith principles set forth in FM 4-5.

d. Assignment and pickup of motor torpedo boattargets. During the searching phase, the searchlightassigned to the AMTB battery may be controlledby the searchlight officer in the manner outlined insubparagraph c. When a particular target is to beengaged by the AMTB battery, control of the AMTBsearchlight is exercised by the battery commander.

(1) Position data for pointing the AMTB search-light will be obtained initially from higher head-quarters (surveillance radar). If control is relin-quished to the battery commander before the lightis put in action, position data will be determinedduring the interval by the radar set assigned to thebattery.

(2) Because of the speed and maneuverability tobe expected of motor torpedo boats, elapsed timebetween the assignment of targets and the turningon of the searchlight must be kept to a minimum.Whenever motor torpedo boats are detected in thearea covered by the harbor defense radar, the AMTBsearchlight is ordered to STAND BY with power on andthe DEC system oriented and synchronized. Whenit becomes apparent that a target being tracked byradar is following a course which may bring it intothe battery's field of fire, azimuths determined byradar and relocated on a board in the BC stationshould be relayed to the searchlight at frequentintervals. Each time, the searchlight should be trav-ersed to the indicated azimuth by distant electriccontrol. The light commander should check eachtime to see that the proper reading appears on the

23

azimuth scale at the searchlight. When it is desiredto place the light in action, the battery commandercommands: IN, AZIMUTH (relocated azimuth withno allowance for dead time).

(3) The searchlight beam will be spread at theorder of the battery commander for illumination ofmotor torpedo boat targets at ranges less than 5,000yards. In addition to facilitating the task of trackinghigh-speed, maneuvering targets, the added beamwidth compensates for errors in radar azimuth dataand for any possible delay in relaying data fromthe radar station to the searchlight.

e. Employment of spread-beam lenses. (1) Thesearchlight beam is spread whenever a high-speed,maneuvering target is to be tracked at a range lessthan 5,000 yards. (Use of the spread-beam lensesreduces the maximum expectable range of thesearchlight about 35 percent.) The increased widthof the beam reduces the possibility of a target escap-ing illumination by maneuvering and facilitatesspotting of the fall of shots.

(2) Searchlights equipped with spread-beam lensesmay also be used for rapid searching of close-in waterareas and illumination of beach defense areas.

(3) The change from normal to spread beam orfrom spread to normal beam is made at the commandof the officer exercising searchlight control, whocommands: (Searchlight number) SPREAD (CON-TRACT) when he desires that the change be made.The command SPREAD may be combined with the com-mand STAND BY or the command IN (Searchlight num-ber, SPREAD, IN), if it is apparent that the target to beilluminated will be at a range less than 5,000 yardsfrom the searchlight when the searchlight is placedin action.

(4) Modified spread-bea:m performance (longerranges with a narrower beam) may be achieved byclosing two of the four spread-beam lenses. Thetwo-lens combinations likely to be useful are thetwo lower lenses, the two upper lenses, or two diag-

24

onally opposite lenses. If spread-beam operation isdesired at extreme ranges, the usable range ofspread-beam searchlights can be further increasedby directing two or more spread beams on the samearea. The decision to employ any of these expedientsdepends on the local situation. Circumstances inwhich two-lens operation will be used and designa-tion of the lenses to be employed should be part oflocal SOP. The appropriate command for two-lensoperation is SPREAD ONE-HALF.

f. References. The employment of seacoast artil-lery searchlights is discussed in detail in FM 4-5.

18. EMERGENCY ANTIAIRCRAFT ARTILLERYROLE. a. Missions. Seacoast artillery searchlightshave the equipment necessary to act as-

(1) Carry lights in the local antiaircraft searchlightdefense.

(2) Carry lights or control point markers in anantiaircraft belt defense of a coastal frontier.

(3) Pickup lights where assigned to AMTB batter-ies equipped with SCR-268 or radar set AN/TPL-1.

b. References. For particulars of searchlight em-ployment in the missions mentioned above, seeFM 44-6 and FM 4-5.

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CHAPTER 4

DUTIES OF PERSONNEL

19. PLATOON COMMANDER. The platoon com-mander is responsible for-

a. Training of personnel. He is charged withseeing that personnel receive thorough training inthe operation of materiel, its care and maintenance,and destruction. He must assure himself that thechiefs of section and light commanders under hiscommand are thoroughly conversant with the tacticsand technique of searchlight operation.

b. Emplacement and maintenance of equipment.He will supervise the emplacement of searchlights,searchlight equipment, and machine guns on sitesselected by higher authority, or will himself selectsites satisfactory for the performance of missionsassigned by higher authority. He will assure him-self, by frequent inspection, that equipment underhis control is properly serviced and maintained bysearchlight personnel.

c. Camouflage of equipment. Within the limita-tions prescribed by higher headquarters, he willselect sites suitable for camouflage. He will pre-scribe the type of camouflage to be used, and willassure himself, by frequent inspections, that camou-flage discipline is being observed.

d. Tactical efficiency of the searchlight squadsunder his command. At every opportunity, he willcheck the ability of the searchlight personnel toorient and synchronize their instruments, and theirability to detect and track targets. He will directand supervise training to correct deficiencies dis-covered by these checks.

26

e. Administrative duties with regard to mess,supply, transportation, reports, and medical care.

f. Maintenance of high morale among personnel.

20. PLATOON SERGEANT. The platoon sergeant-a. Assists the platoon commander in the per-

formance of his duties.b. Takes command of the platoon in the absence

of the platoon commander.

21. CHIEF OF SECTION (SECTION LEADER). Thechief of section-

a. Receives and passes on commands of the platooncommander and the platoon sergeant relative to hissection.

b. Assumes responsibility for the tactical andtechnical performance of men assigned to his sectionunder circumstances which remove him from thedirect supervision of the platoon commander andthe platoon sergeant.

c. Supervises, under the direction of the platooncommander, the occupation and organization ofpositions by searchlight squads assigned to his sec-tion.

d. Assists the platoon commander in trainingoperating personnel.

e. Supervises first echelon maintenance of trans-portation assigned to his section.

22. LIGHT COMMANDER. The light commander-a. Has direct control of the searchlight squad

during tactical operation.b. Is responsible for the proper execution of the

commands of the searchlight officer.c. Supervises orientation and synchronization of

the searchlight system daily at nightfall and directschecks on orientation at frequent intervals (orien-tation should be checked each time power is turnedon if power is turned off after initial daily orien-tation).

27

d. Reports failure of the distant electric controlsystem and regroups his squad for extended handcontrol operation.

e. Acts as an observer during operation underextended hand control, taking station 50 to 100 feetto the flank of the searchlight. From this position,he directs the extended hand control operator byvoice command during detection and tracking oftargets. (An observer displaced from the light inthis manner can see targets more clearly than theoperator at the extended hand controller.)

f. Supervises first echelon maintenance of thesearchlight, control station, and power plant.

23. CONTROL STATION OPERATOR. The controlstation operator-

a. Mans the control station during tactical oper-ation using distant electric control.

b. Mans the extended hand controller in the eventof failure of the distant electric control system.

c. Orients the control station on a selected orientingpoint when directed to do so.

d. Performs first echelon maintenance of the con-trol station.

24. POWER PLANT OPERATOR. The power plantoperator-

a. Starts and stops the power plant when directedto do so and supervises its operation while it is run-ning.

b. Manipulates the power plant controls to main-tain proper readings on the meters.

c. Operates the power plant manually in the eventof failure of the automatic controls.

d. Performs first echelon maintenance on thepower plant.

25. SEARCHLIGHT OPERATOR. The searchlightoperator-

a. Observes the arc continually during operationand makes necessary adjustments.

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b. Places the light in operating condition immedi-ately upon occupation of a position.

c. Observes the searchlight arc meters continuallyduring operation and makes adjustments necessaryto maintain the arc current at 150 amperes and thearc voltage at 78 volts.

d. Orients the searchlight on a selected orientingpoint whenever directed to do so.

e. Performs first echelon maintenance on thesearchlight.26. ELECTRICIAN. The searchlight electrician-

a. Performs second echelon maintenance on search-light and control station equipment.

b. Performs second echelon maintenance on theelectrical system of the power plant.27. COMMUNICATIONS SECTION. a. The com-munications section of a harbor defense searchlightplatoon-

(1) Installs and maintains any field telephonelines operated by the platoon.

(2) Aids in maintaining tactical lines as may bedirected by the searchlight battery commander.

b. The communications section of headquartersbattery of a 155-mm gun battalion installs communi-cations for the searchlight platoon of headquartersbattery.28. TRUCK DRIVERS. Truck drivers assigned tosearchlight sections in mobile artillery organizations-

a. Perform first echelon maintenance on trucksand trailers assigned to the section.

b. Drive trucks assigned to the section as required.29. MACHINE GUNNERS. Machine gunners as-signed to local protection of seacoast searchlights-

a. Site their machine guns as directed by theplatoon commander.

b. Clean and lubricate their machine guns daily.c. Check head space daily.d. Open fire on enemy aircraft, boats, or ground

targets if attacked or when directed to do so by theplatoon leader.

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CHAPTER 5

NOTES ON SERVICE OF' THE SEARCHLIGHT

Section I. OPERATION

30. GENERAL. The principal technical problems ofsearchlight operation are lamp control, synchroniza-tion and orientation of the set, operation of the DECsystem, and extended hand control. These problems,although basic to operation of seacoast searchlights,vary somewhat with different searchlight modelsand will be discussed only generally here. Each iscovered in detail in the technical manual describingthe searchlight model concerned. The manipulationof spread-beam lenses, a problem peculiar to seacoastartillery searchlight equipment, is discussed in detailherein.

31. LAMP CONTROL. a. Lamp control requiresthe correct positioning of the positive and negativecarbons with respect to each other and with respectto the lamp head (fig. 12). When the lamp controlmechanism is functioning properly, the carbons arepositioned automatically. In the event of failure ofthe automatic control system, semiautomatic ormanual control (app. II) may be used. Wheneverthe searchlight is in operation, the searchlight oper-ator must monitor the arc continually, using thepeep sights and the ground-glass finder for thepurpose.

b. The carbons must be positioned so that-(1) The positive carbon protrudes 11/16 inch from

the positive nose cap (Sperry). Protrusion of asmuch as 3/4 to 7/8 inch is permissible on General Elec-

30

tric searchlights. This is checked by viewing thepositive carbon through the ground-glass finder. Thetip of the carbon should be at the black line on thefinder. It must never be permitted to burn back tothe red DANGER line on the finder.

CARBON CARBON

Figure 12. Lamp (equipped with AA spread-beamdevice).

(2) The tip of the positive carbon is maintainedat the focal center of the mirror. The tip of thepositive carbon is the actual light source of the

31

searchlight. If it is displaced only 3/s inch from thefocal center of the mirror, the beam candlepower ofthe searchlight is reduced 40 percent, which reducesthe effective range by 20 percent. The proper posi-tion of the positive carbon tip is marked by the blackline on the ground-glass finder. If it is off this linebecause of insufficient protrusion from the positivenose cap, adjust the positive feed mechanism. Ifpositive carbon protrusion (viewed through the peepsight) is correct, adjust the focusing knob or thespread-beam handwheel to bring the carbon to theproper position.

(3) The correct arc length (distance between thepositive and negative carbons) is maintained. Thisis determined by the readings of the arc voltmeterand the arc ammeter on the trunnion arms of thesearchlight. When the arc length is correct, arc cur-rent is 150 amperes and arc voltage is 78 volts.

c. When the lamp is turned on (by closing the arcswitch), the negative carbon must feed forward untilit touches the positive carbon and then retract at onceto the proper arc length. This is known as strikingthe arc. It is usually accomplished automaticallywhenever the arc switch is closed. In the event offailure of the automatic mechanism, it can be accom-plished manually by feeding the negative carbonuntil contact has been made and immediately re-tracting the negative carbon until the proper currentand voltage values are read on the arc meters.

d. The useful life of a pair of carbons is about 12hours of operation. Whenever the lamp is turnedoff, and at frequent intervals during operation, thecarbons should be inspected (through the peep sights)to make sure that they are sufficiently long. Whenthe blunt end of either carbon is seen to be within2 inches of the lamp head, the carbon should be re-placed. Recarboning is accomplished as follows:

(1) Enter the drum. MIake sure that the DECsystem is deenergized or disconnected from thesearchlight. (Methods of disconnecting the DEC

32

system differ with different searchlight models. Seeappropriate technical manuals.) If recarboning isbeing done at night, the recarboning lamp should belighted.

(2) Remove used carbon stubs, using recarboningtongs to handle the stubs (if the lamp has just beenin operation, they will be extremely hot). The car-bon stubs may be disengaged by manipulation of thepositive and negative carbon release levers (nomen-clature of these levers differs with different search-light models). If necessary, the carbon stub maybe dislodged by inserting the new carbon behind itbetween the feed rollers and pushing forward untilthe stub can be grasped by recarboning tongs. Donot drop carbon stubs or new carbons on the mirror.

(3) Insert new carbons between the feed rollers.Full-length, unused carbons should always be used forrecarboning and both carbons should always be re-placed at the same time. Adjust the protrusion ofthe positive carbon beyond the positive nose cap (par.31b). Position the negative carbon so that its tip isfairly close (14 to 1/2 inch) to the tip of the positivecarbon (this adjustment is not critical).

(4) As each carbon is inserted, engage it with thefeed rollers by restoring the release lever to its oper-ating position. Do not allow the release lever to snapback into place as this may break the carbon.

(5) Leave the drum, close drum doors tightly,turn out the recarboning lamp, and reengage theDEC system.

(6) Reorient the light with the control station.The searchlight is now ready for operation.

e. Details of semiautomatic and manual operationof the Sperry and General Electric M1942 search-lights, with appropriate nomenclature for the twomodels, will be found in appendix II. For earliermodels of either type, see appropriate technicalmanuals (app. I).

32. SYNCHRONIZATION AND ORIENTATION.a. General. Operation of the searchlight by distant

33

electric control is possible only after the DEC sys-tem has been actuated, synchronized (so that anangular movement of the control unit causes anequal angular movement of the searchlight in thesame direction), and oriented (so that azimuth circleson both searchlight and control station read the cor-rect azimuth of the searchlight beam at all times).

b. Actuating the DEC system. A number of con-trols must be operated in order to actuate the DECsystem of a searchlight. The nomenclature of thecontrols operated and the operations performed varysomewhat for different searchlight models. Thisparagraph outlines the necessary procedures forM1942 searchlights of both types. For other search-light models, see appropriate technical manuals.

(1) The DEC system of the Sperry M1942 search-light is actuated when the power is on, the cables areconnected, all drum doors are closed, the DEC trans-fer switch (at the control station) is set at MANUAL,the dynamotor switch (in the junction box) is set atDYNAMOTOR, the azimuth clutch lever is set atOPER, the elevation clutch handle is set to MOTORDRIVE, the elevation lock handle is set at OPER, andthe DC switch (on the junction box) is ON.

(2) The DEC system of the General Electric M1942searchlight is actuated when the power is on, thecables are connected, the DEC transfer switch is setat MANUAL, the AC selector switch is set at DYNA-MOTOR, the azimuth and elevation clutch levers areset at DEC, the elevation brake is OFF, and the azi-muth and elevation amplidyne switches are ON.

c. Synchronization. Model 1942 searchlights aresynchronized as follows: Adjust the controls for DECoperation (subpar. b above), but do not turn ON theDC switch (Sperry) or the azimuth and elevationamplidyne switches (General Electric). (If any ofthese switches is ON, injury to personnel or damageto materiel may result.) Now rotate the observer'sazimuth handwheel at the control station until theneedle on the azimuth zero reader at the searchlight

34

is on the zero index. (Check to see that clockwisemovement of the control unit causes a right deflectionof the zero reader needle.) Rotate the observer'selevation handwheel at the control station until theneedle on the elevation zero reader at the searchlightis on the zero index. (Visual signals,-hand by dayor flashlight by night-are used by the light com-mander to indicate to the control station operator theamount and direction of the necessary movement ofthe handwheels.) Turn ON the DC switch (Sperry)or the azimuth and elevation amplidyne switches(General Electric). The searchlight may jumpslightly. The searchlight and control station are nowsynchronized. (Note. Synchronization is the onlypurpose for which zero readers are used in seacoastsearchlight operation. This is possible on M1942searchlights because the zero readers at the search-light indicate the position of the searchlight withrespect to the control station. .On earlier searchlightmodels, the zero readers at the searchlight indicatethe position of the searchlight with respect to thedetector.)

d. Orientation. For seacoast artillery purposes,the searchlight and control station must be orientedin azimuth (to the nearest degree) on a distant datumpoint. Model 1942 materiel is oriented as follows:Aim the searchlight manually at the orienting point,using the orientation sight. Synchronize searchlightand control station (subpar. c above). If the search-light line of sight jumps off the orienting point whenthe azimuth and elevation drive subsystems areenergized (by closing the DC or amplidyne switches),use the azimuth synchronizing crank (Sperry) or theazimuth corrector knob (General Electric) to movethe line of sight back to the orienting point. Slipthe azimuth scale of the searchlight to read the azi-muth of the datum point. Slew the control unituntil the azimuth circle at the control station readsthe azimuth (from the searchlight) of the orientingpoint. When these steps have been carried out, thesearchlight and control station are oriented.

35

e. Checks of synchronization and orientation. Thesearchlight set is synchronized and oriented dailyjust before dark. The synchronization and orienta-tion of the set must be checked each time power isapplied (if power is turned off after the initial syn-chronization and orientation). At the commandSTAND BY, the light commander of a squad operatingM1942 equipment supervises the setting of the con-trols for DEC operation. Before the DC switch(amplidyne switches) is turned ON, he checks to seethat the zero readers at the searchlight are centered.If they are not, he commands: (Searchlight number),CONTROLLER, SYNCHRONIZE over the telephoneand then uses visual signals to indicate to the controlstation operator the amount and direction of move-ment necessary. When the readers are centered, hereports, "(Searchlight number), azimuth (readingof searchlight azimuth scale)." The control stationoperator then slews the control unit (if necessary)to read the azimuth indicated, and the system isoriented and synchronized.

33. DISTANT ELECTRIC CONTROL. a. General.The searchlight beam can be moved to any point inthe area it covers by movement of the observer'sazimuth and elevation handwheels, when the DECsystem has been actuated, synchronized, and oriented(par. 32). In operation, the searchlight is initiallyset to a point in elevation (determined by experi-mentation) which affords maximum illumination ofthe water area to be covered. An initial azimuth isordered by the officer exercising searchlight control.When a target is picked up, the searchlight is elevatedor depressed until illumination of the water areabetween the searchlight and target is reduced to aminimum, and moved in azimuth as necessary toprovide maximum visibility for observers (FM 4-5).The target is tracked by moving the azimuth andelevation handwheels at the control station as neces-sary to keep the target in the searchlight beam. If

36

the control station operator is following the targetthrough a binocular mounted on the control station,he slews the binocular mount independent of thecontrol station as necessary in order to keep thetarget in view.

b. Illumination of targets. (1) When a target isassigned by the searchlight Qfficer (par. 17c), thecontrol station operator moves the control unit, bymeans of the observer's azimuth handwheel, to theazimuth directed and acknowledges the commandby reporting over the telephone, "(Searchlight num-ber), controller, (azimuth directed)." (If more thanone searchlight is concerned, control station opera-tors report in order of the searchlight numbers-light 1 before light 2, etc.) The searchlight operatorchecks to see that the azimuth scale on the search-light reads the proper azimuth. If it does, the search-light operator reports, "(Searchlight number), inorder," and the searchlight officer commands:(Searchlight number), IN. If the searchlight azi-muth scale reads incorrectly, the searchlight opera-tor reports, "(Searchlight number), DEC out oforder," and the control station operator and lightcommander take posts for extended hand control(par. 34).

(2) Examples. (a) The searchlight officer de-sires to illuminate a target, crossing right to left withrespect to the searchlight, which is being trackedby surveillance radar. The relocated azimuth fromsearchlight 4 to the target is 270, and the plottedcourse of the target indicates that it will travel about1°, with respect to the searchlight position, during 20seconds [this need not be accurate, due to the beamwidth of the searchlight and the 10° sector of searchspecified in par. 33b (3)]. The searchlight officercommands: FOUR, AZIMUTH TWO SIX NINE.The control station operator at searchlight 4 traversesthe control unit until its azimuth circle reads 269,and reports, "Four, azimuth two six nine." Thesearchlight operator observes that the azimuth scale

37

on the searchlight reads 2:69 (any reading between268 and 270 is satisfactorily accurate), and reports,"Four, in order." The searchlight officer commands:FOUR, IN.

(b) If the reading of the azimuth scale at thesearchlight is incorrect, the searchlight operatorreports, "Four, DEC out of order." The light com-mander and control station operator take posts forextended hand control (par. 34), and the searchlightoperator reports, "Four, hand control in order." Thesearchlight officer then commands: FOUR, IN, AZI-MUTH TWO SIX ZERO (giving a relocated azimuthwith no allowance for dead time). The searchlightis moved manually to the azimuth directed, and thesearchlight operator turns on the lamp. [The targetis then picked up as prescribed in paragraphs 17cand 33b (3).] As soon as the tactical situation per-mits, the searchlight is turned off and the DEC ischecked to determine the cause of the malfunction.

(3) When the searchlight is turned on, the controlstation operator looks for a target in the beam. Ifnone is visible, he immediately searches through 50on either side of the azimuth at which the light wasordered IN. If no target is detected in the 10° sectorof search, the searchlight squad awaits further ordersfrom the searchlight officer (par. 17c), meanwhilecontinuing a systematic search in the 10° sector.

34. EXTENDED HAND CONTROL. Extended handcontrol is used only when distant electric controlfails (par. 33). After reporting "DEC out of order,"the searchlight operator sets the controls for ex-tended hand control (app. II). The light commanderand searchlight operator place the extended handcontroller in its socket, mesh it with the elevationgearing, and check its operation. The searchlight isthen operated by hand control as specified in para-graph 33, with the light commander operating theextended hand controller and the searchlight opera-tor performing his usual task of monitoring the per-

38

formance of the searchlight. The control stationoperator comes from the control station to the search-light as rapidly as possible. When the control stationoperator arrives, the light commander turns over theextended hand controller to him and takes post ap-proximately 50 feet to the flank, as an observer. Per-sonnel continue to perform these tasks as long asextended hand control is necessary.

Section II. SPREAD-BEAM LENSES

35. MANIPULATION. a. General. The searchlightoperator changes the spread-beam lenses from thenormal (or spread) beam to the spread- (or normal-)beam position, as outlined in subparagraphs b and cfollowing, at the command of the officer exercisingsearchlight control (subpars. 17d and 17e). Theoperations necessary to change the position of thelenses are simple and are readily apparent from aninspection of the hinge construction. (See details ofhinge construction in figs. 13 and 14.) It is desirable,however, to establish and practice a standard pro-cedure in order to attain speed and dexterity. Thefollowing paragraphs outline a suggested procedurefor changing the position of the lenses.

b. Changing from normal to spread beam. (1) Re-lease the holding hooks on the upper and lowerlenses. Standing to the right of the light (fig. 15),grasp the bottom of the lower lens with the righthand and the top of the lens with the left hand. Liftthe lens from the locking slot, rotate it until its planeis parallel to the beam of the light, then push thetop of the lens with the left hand and allow the hold-ing rod to move down the slotted track of the upperbracket to the end of the slot. Next, close the lensinto the spread-beam position, and lower it into thelocking slot.

(2) To move the upper lens, grasp it with bothhands and lift it from the locking slot. Close thelens into the spread-beam position and lower it intothe locking slot.

39

(3) Move across the front of the light to left sideand repeat the same series of operations for the lowerand then the upper lens, with the positions of theright and left hands interchanged.

Caution: Do not look directly into the arc flame ofthe lamp or the reflection of the arc in the mirror.

Figure 13. Mounting of spread-beam lenses (Lower lens).

(4) Note that the holding hooks are not reengagedas a part of the procedure above. Under service con-ditions, the holding hooks should be reengaged assoon as possible after the beam has been spread(contracted) and the searchlight is again following

40

the target smoothly. In training, the holding hooksshould be reengaged as soon as all four lenses havebeen opened or closed. The searchlight should neverbe operated for any length of time with the holdinghooks disengaged, as there is always a chance of thelens slipping from the locking slot and damaging theequipment.

Figure 14. Mounting of spread-beam lenses (upper lens).

c. Changing from spread beam to normal beam.Reverse the operations listed under a preceding, beingsure to open the upper lens first and then the lowerlens, first ori one side and then the other.

d. Priority of operations. When the searchlight isnot in use, or during periods when the squad is at

41

REST, the lenses are kept in the spread-beam position.At the command STAND BY, the lenses are opened,unless otherwise ordered by the searchlight officer orotherwise specified in local. SOP. When the commandSPREAD (CONTRACT) is combined with another com-mand (par. 17e), the searchlight operator manipulatesthe lenses only after performing all other actionsdirected by the command (i.e., after the DEC systemhas been synchronized and oriented at the commandSTAND BY or after the lamp has been turned on atthe command IN).

CENTER LINE OFSEARCHLIGHT

ROTATE

I a LOWER

PUSHDOWNTRACK - ROAT

ROTATE

L FT

Figure 15. Manipulation of spread-beam lenses.

36. TRANSPORTATION. When the searchlight isto be transported by truck, trailer, or shipped fromone place to another, the spread-beam lenses (withholdings rings), the lens-holding rods, and the coun-

42

terweights must be removed and packed in the car-rying case provided for the purpose. The mountingbrackets and the counterweight holding frame andcrank need not be removed from the searchlight.

a. Removing spread-beam equipment. (1) Set thesearchlight drum at an elevation of 0 mils and lockthe elevation brake.

(2) Remove the upper lenses. Each lens is re-moved by taking the cotter pin out of the holding rodand withdrawing the holding rod. (Hold the lenssecurely to prevent it from falling.) Then removethe lens and holding ring and place them in a safeplace near the carrying case.

(3) Remove the lower lenses. The lower lensesare removed in the same manner as the upper lenses(subpar. (2) preceding).

(4) Release the counterweights by turning theholding crank counterclockwise. Remove the coun-terweights from the holder and turn the holdingcrank clockwise as far as it will go without damagingthe searchlight drum. Care should be taken to pro-tect the counterweight assembly against any jarringblows as the assembly may be dislodged from thedrum.

b. Packing spread-beam equipment. (1) Removeall accessories from the lens carrying case and thenpack the equipment in the carrying case in the fol-lowing order:

(a) Counterweights.(b) Lens-holding rods.(c) Lens holder shelf.(d) Spare lens (place flat on holder shelf).(e) Wooden blocks.(f) Lenses.(2) To pack the lenses, proceed as follows:(a) Place one wooden block in each corner of the

case, with the cut-out portion on the bottom and thehole in the block fitting over the wood dowel in theshelf. Match the color of the dots on the block andthe case.

43

(b) Place one lens, complete with holding ring, onthe four corner blocks.

(c) Pack the remaining lenses, using corner blocksto separate each lens from the others. (Corner blocksfor each lens are placed as in (a) above.)

(d) Place one block in each corner of the case ontop of the last lens packed. This is necessary be-cause the springs mounted on the lid must engagethese blocks to keep the lenses in place.

(e) Close the top carefully.c. Reassembly of spread-beam equipment. (1)

Set the searchlight drum at an elevation of 0 mils andlock elevation brake.

(2). The procedure for unpacking and reassemblingspread-beam equipment is essentially the reverseof the procedures outlined in a and b above. Cornerblocks, spare lenses, and lens holder shelf are re-placed in the carrying case after other equipment hasbeen unpacked.

Section III. POWER PLANT OPERATION

37. GENERAL. a. Operation of the searchlight pow-er plant is essentially the same as operation of anyportable power plant. After starting the power plantand making cable connections necessary to supplypower to the searchlight, the power plant operatorstands by the plant, watching for malfunction of theequipment and making such control settings as arenecessary to supply proper control and arc power tothe searchlight.

b. The following paragraphs outline proceduresfor power plant operation.. For detailed procedures,see the appropriate technical manuals (listed inapp. I).

38. STARTING THE POWER PLANT. a. The pow-er plant is started in the same manner as an auto-mobile engine; by turning on the ignition, adjustingchoke and throttle controls, and manipulating the44

starter until the engine catches. The front door ofthe power plant should be open to provide a flow ofair for the cooling system. If the electric startingsystem should fail, the power plant can be started byusing the crank supplied with the equipment. Whenthe engine is running, the choke is adjusted asnecessary for smooth operation. After a few minutesof smooth running, the throttle is pulled to the wide-open position. Engine speed, as indicated on thetachometer, should approximate the no-load valuefor the power plant being used. (See table, par. 42.)If the tachometer reading with the throttle wideopen is considerably more than the no-load value,the power plant must be operated manually. Beforestarting the power plant, the operator should checkto make sure that the main power switch is OFF.This switch must never be turned ON until all cableshave been connected and power is to be supplied tothe searchlight.

b. Whenever the power plant is started, it shouldbe run long enough to bring the engine up to oper-ating temperature before being stopped.

39, CABLE CONNECTIONS. The two power cablesare connected from the output receptacles on thepower plant to input receptacles on the junction boxof the searchlight. The cables may be connectedeither before or after the power plant has beenstarted.

40. CONTROL-LOAD OPERATION. After the pow-er plant has been started and adjusted to no-loadoperating speed and the cables have been connected,output voltage of the power plant should be adjustedto a preliminary voltage (listed under no-load valuesin the table, par. 42). The main power switchis turned ON when ordered by the light commander.(The arc switch at the searchlight should be OFFwhen the main power switch is first turned ON.)The operator checks to see that the output meters

45

read control-load values, adjusting the rheostat.ifnecessary.

41. ARC-LOAD OPERATION. After control oper-ation of the power plant and the DEC system havebeen checked, the arc should be struck. Output volt-age and engine speed at the power plant will decreasewhen the lamp is turned on. The field rheostatshould be adjusted to obtain the arc-load reading(see table, par. 42) on the power plant voltmeter.The governor should adjust engine speed automati-cally to the proper value.

42. OPERATING VALUES. a. The following tablelists approximate values of voltage, current, andengine speed for different operating conditions forthe 1942 models of both types of searchlights:

Power plant Power plant Searchlight Searchlightvoltmeter ammeter voltmeter ammeter

(volts) (amperes) (r.p.m.) (volts) (amperes)

Sperry G.E. Sperry G.E. Sperry G.E. Sperry G.E. Sperry G.E.No-load values ..... 105 110 0 1, 150 1, 250 0 0 0 0Control-load values. 105 110 15 15 1, 150 1, 250 105 110 0 -0Are-load values .... 100 100 165 165 1, 100 1, 190 78 78 150 150

b. If it is impossible to obtain the readings listedabove on all meters during arc-load operation, thepower plant output should be adjusted as necessaryto obtain the proper readings on the searchlight volt-age and current meters. Arc voltage must be main-tained at 78 + 2 volts and arc current must be main-tained at 150 amperes for efficient operation.

c. Engine meters on the control panel of the powerplant should read within the following limits: waterthermometer, 160°-180°; oil pressure, 15-25 pounds.The charging ammeter may read between +5 and+15 amperes (Sperry) or between 0 and +25 am-peres (General Electric), depending on the state ofcharge of the battery.

46

43. MANUAL OPERATION. If governor control ofengine speed should fail, the governor should beblocked or tied in its wide-open position and enginespeed maintained at proper values by adjustment ofthe throttle control.

Note. When the power plant is operated manually, theoperator must push in the throttle quickly when changingfrom arc-load to control-load operation (whenever thelamp is turned off). Failure to do this will cause the en-gine to overspeed, generating a high voltage which willburn out motors and lamps.

44. STOPPING THE POWER PLANT. The follow-ing procedure should be followed in shutting downthe power plant:

a. Turn off the main power switch.b. Push in the throttle and allow the engine to idle

for 10 to 15 minutes.c. Turn off the ignition switch.d. Turn off panel lights and close engine and con-

trol panel doors.e. Disconnect power cables and cover receptacles.

45. TRANSPORTATION. The power plant shouldbe prepared for transportation by turning off all con-trol panel switches, closing and latching or lockingall doors on the unit, and closing and latching thetool box. Tire pressure should be checked. (Theproper tire pressure is 32 pounds.)

Section IV. SAFETY PRECAUTIONS

46. GENERAL. a. The same precautions should beobserved in operating searchlight equipment as areobserved with any high-current apparatus. Theequipment is designed for a maximum of safety, butconstant checks must be made on the condition ofthe wiring system and the protective systems toforestall short circuits or mechanical malfunctionswhich might cause injury to personnel or damage toequipment.

47

b. In addition to the specific precautions men-tioned elsewhere in this manual, the following safetymeasures should be observed scrupulously:

(1) Keep clear of the searchlight when it is beingmoved by distant electric control. The azimuth andelevation drive mechanisms have sufficient powerto cause serious injury to anyone struck by the drumwhen it is moving rapidly. The duties of the search-light operator may require him to approach the drumwhile it is being traversed electrically, but he shoulddo so with caution.

(2) Keep clear of exposed electrical apparatus. Ifthe searchlight is being operated with one or moreof its control elements uncovered, points of danger-ously high voltage may be exposed. Voltages ashigh as 440 volts develop in azimuth and elevationcontrol and drive elements of a 1942 searchlightwhen the searchlight is moving rapidly.

48

CHAPTER 6

FIELD OPERATIONS

47. SELECTION OF POSITIONS. a. Tactical con-siderations. For tactical considerations affecting thesiting of Coast Artillery searchlights, see FM 4-5.

b. Positions for other elements of the searchlightset. After a position satisfying tactical requirementshas been selected for the searchlight, positions shouldbe chosen for other elements of the searchlight (fig.16). The control station should be located on eitherflank of the searchlight as far from the searchlightas the control cable permits and at a height approxi-mately 20 feet lower than the searchlight. The con-trol station may be located in a base-end station ifconvenient. The power plant should be sited in adirection away from the shore line as far from thesearchlight as the power cables permit. (Additional200-foot lengths of power cable may be added to theissue cables up to a total length of 600 feet. Theballast resistor must be adjusted for operation with400 or 600 feet of cable.) Power plant and controlstation sites should be widely separated. The ma-chine gun assigned for local defense of the search-light should be sited 50 to 100 yards from the search-light in a position affording good fields of fire againstlow-flying aircraft, motor torpedo boats, and groundavenues of approach. If no single position fulfillingthese requirements can be found, supplementarypositions should be designated. Alternate positionsfor primary and supplementary positions should bedesignated. The platoon commander, in his groundreconnaissance, should also designate bivouac areasfor searchlight personnel.

49

2a

I~~~~~~~~~~~~~~IW W ~ ~ ~ ~ ~ 4,

o

W~~~~~

20

oo

I'~~~~~ (~ -.:.0~i

.

! I

50'-

co~ ~ ~ ~~~o

so~~~~~~~~~

w~~ w )C~I 0.Co I..

~~ia~!

50~~~~~

48. OCCUPATION AND ORGANIZATION OFPOSITION. a. Following the selection of a site bythe platoon commander, detailed information as tothe sites selected for the elements of the searchlightset should be passed on to section leaders and lightcommanders. Movement into position will be di-rected by section leaders and light commanders,supervised by the platoon commander and theplatoon sergeant.

b. Members of the searchlight squad should betrained in a standing operating procedure for speedyoccupation of field positions. This is particularlyimportant in the case of semimobile organizationswhere the scarcity of transportation requires a highdegree of efficiency in its use. A suggested SOP formovement into position follows:

(1) Equipment should be loaded as follows: ex-tended hand control and spare carbons in the search-light trailer; control station (including binocularmount), telephones, control cable, and power cablesin the truck towing the searchlight; machine gun andammunition chests in the truck towing the powerplant. (See FM 44-75.) If strafing or low-levelbombing attack is considered likely en route to theposition, the machine gun should be carried in firingposition, manned and ready, throughout the move-ment. If the move is to be a long one over roughroads, it may be necessary to carry the power plantin the truck rather than tow it. It will not be possi-ble to carry the power plant and mount the machinegun in the same truck.

(2) Personnel should be carried as follows: lightcommander, searchlight operator, and control stationoperator in the truck towing the searchlight; machinegunners and the power plant operator in the trucktowing the power plant. The section leader shouldride with the first squad of his section to move intoposition. The platoon leader and the platoon ser-geant should have the use of one of the batteryadministrative vehicles during movement into posi-tion.

51

(3) The truck towing the searchlight proceeds tothe searchlight position (or as near to it as terrainand camouflage discipline will permit). The traileris uncoupled and the searchlight and a telephoneare unloaded and prepared for operation. The search-light operator remains with the searchlight. Thetruck proceeds to the position selected for the controlstation, unreeling the control cable and telephonewire as it goes. At the selected site, the controlstation and the other telephone are unloaded andset up. The control station operator remains withthe control station. The truck then returns to thesearchlight position and moves from there to thepower plant position, unreeling the power cables.

(4) The power plant truck proceeds to the powerplant position, where the power plant is uncoupled(or unloaded). The truck then proceeds to the siteselected for the machine gun and the machine gunis unloaded and set up. The truck then moves tothe searchlight position and picks up the searchlighttrailer.

(5) After completing the movements outlined in(3) and (4) preceding, the trucks return to the batterymotor pool or some other designated point to pickup personnel and equipment of another searchlightsquad. If necessary, the searchlight truck may beused to lay telephone wire from the searchlight posi-tion to the battalion command post. The powerplant truck, towing the searchlight trailer, shouldreturn to the designated point at once to make thetrailer available for loading.

(6) All personnel present assist if heavy work isrequired to place the searchlight, control station, orpower plant in position. (If the searchlight, powerplant, or control station must be manhandled forsome distance over difficult terrain, additional per-sonnel from other searchlight squads should be pro-vided.) Adjustments (leveling, removing transpor-tation accessories, etc.) to the searchlight, controlstation, or power plant are performed by the appro-

52

priate operator after the truck has moved on. Eachoperator checks the operation of his instrument andconnects the cables to the proper receptacles as soonas the cables are laid. The searchlight operator andthe control station operator connect their telephonesto the wire laid between their respective positions.The power plant operator starts the power plant andchecks its performance but does not turn on themain switch until the light commander has checkedto see that the proper connections have been madeat searchlight and control station.

(7) As soon as the readiness of the searchlight sethas been verified by the light commander, the poweris turned on and the set is oriented and synchronized.

(8) When the searchlight set is ready for action,personnel trenches are dug, tents are pitched in thebivouac area, and straddle trenches are dug. Assoon as possible, the searchlight, power plant, controlstation, and machine gun (in the order mentioned)are dug in (FM 5-15) and camouflaged (FM 5-20 andFM 5-20F). All interconnecting cables should beburied. (If the ground at the site is normally frozenduring the winter months, the cables should be buriedin ducts large enough to permit them to be easilywithdrawn. When freezing of the ground is believedto be imminent, the cables should be withdrawn fromthe ducts and strung above ground on pegs highenough to support them above the level of normalsnowfall.)

(9) Telephone lines from the searchlight positionsto the battalion command post should be laid at once,normally by the battery communications section.The searchlight line to the battalion command postmay be connected to the searchlight telephoneseither at the control station or the searchlight, which-ever is more convenient. If the searchlight squadhas only one telephone, it should be installed at thecontrol station.

c. The instructions in subparagraph b assume asituation in which the searchlights must be emplaced

53

and ready for operation without delay. If somedelay is permissible, the searchlight positions shouldbe developed as much as possible (by the construc-tion of searchlight towers; shelters for searchlight,control station, and power plant; personnel shelters;etc.) before occupying the position. Although search-light equipment can be operated in the open, itshould be sheltered if facilities are available and thetactical situation will permit.

49. PROTECTIVE MEASURES. The searchlightposition should be organized for local defense, withdefensive obstacles surrounding the entire area oc-cupied by the searchlight and associated equipment.All elements should be dug in or revetted stronglyenough to provide protection from small-arms fireand bomb and shell fragments (FM 5-15). If possi-ble, the various elements of the system should beconnected by covered routes, and defensive positionsshould be prepared which will permit the searchlightsquad to cover the obstacles and deliver effective fireagainst enemy ground troops. (The weapons nor-mally available to the squad consist of one .50 caliberAA machine gun, which is the primary weapon; one.30 caliber automatic rifle; and four .30 caliber rifles.The grenade launcher M' or the rocket launcher.M9A1 may be made available to the squad at thediscretion of the headquarters battery commander.)The defense is coordinated with the local defensesof other nearby elements.

Note. For further information on local defense ofsearchlight positions and coordination of their defense withother elements of a 155-mm battalion, see FM 4-5. For adetailed discussion of defense against chemical attack, seeFM 21-40. Methods of decontamination of materiel andinfected ground areas are explained in TM 3-220.

50. WITHDRAWAL FROM POSITION. A suggestedSOP for withdrawal from position is as follows:

a. The searchlight truck, towing the searchlighttrailer, proceeds to the searchlight position. The

54

searchlight trailer is uncoupled, and the light com-mander, the searchlight operator, and the controlstation operator load the searchlight into the trailer.The truck proceeds to the power plant position andthen returns to the searchlight, reeling in the powercable as it moves. The power plant operator assistsin reeling in the cable. Back at the searchlight thesearchlight telephone is loaded into the truck andthe control station operator mounts the truck. Thetruck proceeds to the control station. The controlstation telephone is loaded into the truck. Thecontrol station is dismantled and loaded into thetruck by the control station operator and the truckdriver. The truck then returns to the searchlight,reeling in the control cable on the way. The loadedsearchlight trailer is coupled to the truck. The lightcommander, the control station operator, and thesearchlight operator mount the truck which thenmoves to its assigned place in the battery marchcolumn.

b. The power plant truck proceeds to the machine-gun position. The machine gun, water chest, andammunition chests are loaded on the power planttruck. (The gun is mounted in firing position if airattack en route is considered likely.) The machinegunners mount the truck which proceeds to thepower plant. The power plant is coupled to thetruck, the power plant operator mounts the truck,and the truck proceeds to its place in the batterymarch column.

55

CHAPTER 7

CARE AND ADJUSTMENT OF MATERIEL

51. GENERAL. a. Searchlight equipment requiresthe same careful cleaning, lubrication, and adjust-ment as any other complicated machinery. Theequipment is sturdy and should not require frequentadjustment if operated properly.

b. First and second echelon maintenance proce-dures for periodic cleaning, lubrication, and adjust-ment of searchlight equipment and power plants arelisted in FM 44-75. Detailed maintenance procedureswill be found in technical manuals describing specifictypes and models of equipment (app. I).

52. RESPONSIBILITY FOR MAINTENANCE. a.First echelon maintenance of searchlights and as-sociated materiel is the responsibility of the operatingpersonnel.

b. Second echelon maintenance of electromechan-ical systems associated directly with the search-light system (with the exception of the power plantengine) is the responsibility of the searchlight elec-trician. Second echelon motor maintenance (includ-ing trucks, trailers, and the engine of the powerplant) will be performed by mechanics assigned tothe battery, battalion, or harbor defense.

c. Third, fourth, and fifth echelon maintenance ofsearchlight equipment (except trucks) will be per-formed by the Corps of Engineers. Third, fourth,and fifth echelon maintenance of trucks is a respon-sibility of the Ordnance Department.

53. MAINTENANCE PROCEDURES. For mainte-nance charts and procedures, see FM 44-75 and ap-propriate technical manuals (app. I).

56

CHAPTER 8

DESTRUCTION OF SEARCHLIGHT EQUIPMENT

54. GENERAL. Tactical situations may arise whenlack of time and transportation will make it impossi-ble to evacuate seacoast materiel. In such a situation,all materiel which cannot be evacuated must bedestroyed to prevent its use by the enemy againstour own and allied forces. Such destruction shouldbe carried out only by order of the sector or highercommand. The working principles to be followedare as follows:

a. The methods used must be adequate, uniform,and easily followed in the field.

b. If thorough destruction of all parts cannot becompleted, the most important parts should be de-stroyed or removed. The same essential parts mustbe destroyed or removed on all like units to preventthe enemy from constructing one or more completeunits from the damaged ones.

c. The searchlight battery or platoon commandershould prepare plans for the destruction of materielin the event of imminent capture. Such plans shouldmake allowance for variations in available time,equipment, and personnel.

d. All searchlight personnel should be trained inmethods of destruction of the materiel which theyoperate. However, the training should not involvethe actual destruction of materiel.

e. Destruction should be accomplished in the fol-lowing priority:

(1) Searchlights.(2) Small arms.(3) Tires.(4) fVehicles.

57

(5) Communications equipment.(6) Control stations.(7) Power plants.(8) Cables.f. Destruction by any of the methods listed in the

following paragraphs should be accomplished in thesequence indicated. Uniformity of destruction canbe obtained in this way whether or not the methodis carried to completion. Where an alternate methodis indicated, it is not to be used unless the primarymethod is impracticable.

g. Certain of the methods outlined require specialfacilities, such as TNT and incendiary grenades,which may not be regular items of issue. The issueof such special facilities, and the conditions underwhich issued, are command decisions in each caseand depend on the tactical situation.

55. SEARCHLIGHT. a. Use an ax or sledge to smashall external mechanical and electrical equipment,such as the lamp control mechanism, the arc switchassembly, the azimuth and elevation drive and con-trol mechanisms, power meters and zero-reader in-dicators, resistors, and cable receptacles.

b. Break the drum door glass and throw a handgrenade into the drum. If grenades or other explo-sives are not available, shatter the glass in everysegment of the drum door and use an ax, a sledge,or a concentrated burst of .50 caliber machine-gunfire to demolish internal elements of the drum. Makesure that the lamp head is destroyed and that themirror is thoroughly distorted and perforated.

c. If incendiary grenades are available, ignite oneunder each tire. If they are not available, fire aconcentrated burst with a .50 caliber machine guninto each tire and/or douse with gasoline and ignite.

d. Douse the remnants of the searchlight withgasoline and ignite.

56. SMALL ARMS. Methods for destruction ofsmall arms are listed in appropriate field manuals.

58

57. TIRES. a. General. Whenever it appears likelythat vehicles, searchlights, power plants, or otherwheeled equipment may be captured by the enemy,it is essential to destroy the tires even though timedoes not permit destruction of the equipment ofwhich the tires are a part. However, it will usuallybe possible to destroy tires at the same time as theequipment on which they are used.

b. Primary method. Ignite an incendiary grenadeM14 under each tire. If TNT is being used to destroyother elements of the equipment of which the tiresare a part, wait until the incendiary fires are wellstarted before detonating the TNT.

c. Alternate method. Damage the tires with anax, pick, or heavy machine-gun fire. (Deflate tiresfirst, if possible.) Pour gasoline on the tires, dousingeach one, and ignite.

58. VEHICLES. a. General. If explosive chargesare prepared beforehand and carried in vehicles,keep caps and fuzes separated from the charges untilthey are to be used. If possible, detach and evacuateall machine guns mounted in the vehicles beforedestroying the vehicles.

b. Primary method. Remove and empty portablefire extinguishers. Puncture the fuel tanks. Place2-pound charges of TNT on top of the clutch housingof trucks and as low as possible on the left side ofthe engine. Place a 2-pound TNT charge over theaxle inside each wheel of trailers. Insert tetryl non-electric caps with at least 5 feet of safety fuze ineach charge. Ignite the fuzes and take cover.

c. Alternate method. Remove and empty theportable fire extinguishers. Puncture the fuel tanks.Smash all vital elements (such as distributor, car-buretor, radiator, engine block, air and oil cleaners,generator, control levers, crankcase, and transmis-sion) with a heavy ax, pick, or sledge. Pour gasoline,oil, or distillate on entire unit and ignite.

59

59. COMMUNICATIONS EQUIPMENT. a. Tele-phone equipment. Destroy handsets, headsets, chestsets, terminal strips, and battery cases by hammering.Destroy field wire by cutting and burning.

b. Radio equipment (if possessed by the unit).Destroy by smashing all units with an ax, pick, orsledge. Pour gasoline on the remnants and ignite.

60. CONTROL STATION.. a. Remove the coverfrom the control unit and destroy all electrical equip-ment with an ax or sledge!. Pour gasoline into theunit and ignite.

b. Remove the binoculars. If possible, evacuatethem; otherwise, smash them with an ax or sledge.

61. POWER PLANT. For destruction of the tiresand motor elements of the power plant, follow themethods outlined in paragraphs 57 and 58. Place2-pound TNT charges in the generator unit and atthe control panel and detonate with the cap and fuzecombination prescribed for demolition of vehicles.If TNT is not available, smash the generator unit andthe control panel with an ax or sledge. Douse entireunit with gasoline and ignite.

62. CABLES. Smash plugs. Heap cables in a pile,douse'with gasoline, and ignite. If time permits, cutcables-into short lengths before burning.

63. MISCELLANEOUS. Any equipment which hasescaped destruction (including parts which may havebeen thrown clear by the bursting of demolitioncharges) should be piled together with some inflam-mable material such as wood or sawdust. Douse thepile with gasoline, oil, or distillate and ignite.

60

APPENDIX I

REFERENCES

1. FIELD AND TECHNICAL MANUALS.FM 4-5 TacticsFM 5-15 Field FortificationsFM 5-20 Camouflage, Basic PrinciplesFM 5-20A Camouflage of Individuals and Infantry

WeaponsFM 5-20B Camouflage of VehiclesFM 5-20F Camouflage of Antiaircraft ArtilleryFM 5-20G Camouflage of Rear Areas and Fixed

FortificationsFM 21-40 Defense Against Chemical AttackFM 44-6 Employment of Antiaircraft Artillery

SearchlightsFM 44-75 Service of the Antiaircraft SearchlightTM 3-220 DecontaminationTM 4-210 Seacoast Artillery WeaponsTM 5-575 Searchlight, 60-inch, Model 1941 (General

Electric)TM 5-1721 Searchlight, 60-inch, Model 1942 and

Control Station (Maintenance Manual,Sperry)

TM 5-1722 Searchlight, 60-inch, Model 1942 andControl Station. (Parts Catalog, Sperry)

TM 5-1723 Searchlight, 60-inch, Model 1942 andControl Station (Operating InstructionsManual, Sperry)

TM 5-2721 Portable Power Plant for Searchlight, 60-inch, Model 1942 (Maintenance Manual,Sperry)

TM 5-2722 Portable Power Plant for Searchlight, 60-inch, Model 1942 (Parts Catalog, Sperry)

61

TM 5-2723 Portable Power Plant for Searchlight, 60-inch, Model 1942 (Operating InstructionsManual, Sperry)

TM 5-7040 Searchlight, 60-inch, Models 1941 and1941A (General Electric)

TM 5-7044 Searchlight Trailer, Model 1131 Special[Ml]

TM 5-7045 Searchlight, 60-inch, Model 1942 andControl Station (Operating InstructionsManual, General Electric)

TM 5-7046 Searchlight, 60-inch, Model 1942 andControl Station (Parts and Price Lists,General Electric)

TM 5-7047 Searchlight, 60-inch, Model 1942 andControl Station (Maintenance Manual,General Electric)

TM 5-7048 Portable Power Plant for Searchlight, 60-inch, Model 1942 (Parts and Price Lists,General Electric)

TM 5-7049 Portable Power Plant for Searchlight, 60-inch, Model 1942 (Operating Instruc-tions Manual, General Electric)

TM 5-7051 Portable Power Plant for Searchlight, 60-inch, Model 1942 (Maintenance Manual,General Electric)

TM 5-7100 Sixty-inch Antiaircraft Searchlight Equip-ment, Model 1941 (Sperry)

TM 5-7138 Sixty-inch Antiaircraft Searchlight, Model194C (Sperry)

TM 5-7140 Sixty-inch Antiaircraft Searchlight, Model1941A (Sperry) Searchlight, 60-inch,Model 1940 (General Electric)

TM 9-2810 'Motor Vehicle Inspections and PreventiveMaintenance Services

2. SUPPLY CATALOGS.

ASF Catalog ENG 7-S53 Searchlight, 60-inch, withExtended Hand Con-trol, Sperry, M1942

ASF Catalog ENG 7-S55 Searchlight, 6 0 - i nch,General Electric Com-pany, with ExtendedHand Control, Models1942 and 1942A

62

APPENDIX II

TECHNICAL DATA

1. COMPARISON OF GENERAL ELECTRIC ANDSPERRY SEARCHLIGHTS MODEL 1942. a. Ingeneral, the basic operating principles of the GeneralElectric and Sperry searchlights are the same.Within the general operating specifications pre-scribed by the Army, the two manufacturers havedevised specific electrical and mechanical systems,each using the system best adapted to its own manu-facturing facilities.

b. The following table compares the main featuresof the Sperry and General Electric searchlightsM1942. (Words and abbreviations appearing incapital letters indicate exact labeling appearing onthe equipment.)

SPERRY M1942 GENERAL ELECTrRIC M1942

Power plant:

Motive power ........... Six-cylinder Hercules JXD Six-cylinder Hercules JXDgasoline engine. gasoline engine.

Governor .... .......... Centrifugal (Pierce) single- Centrifugal (Pierce) single-speed setting. speed setting.

Speed ................. 1,100 r.p.m ................. 1,200 r.p.m.

Radiator position ......... At front end of power plant... In center of power plant.

Radiator fan ........... D.C. electric-motor-driven.... Engine-belt-driven.

Generator .............. D.C ............... 16.2 kw. D.C ............ 16 kw.

63

SPeRnY M1942 GENnRAL ELECTRIC M1942

Power plant-(contd.).

Current (arc load) ........ 1................ 162 amps. .................. 160 amps.'

Voltage (arc load) ......................... 100 volts .................. 100 volts

Power cables ............ The single-conductor power The single-conductor power

cables, one positive and one cables, one positive and one

negative, each 200 feet long, negative, each 200 feet long,

transmit d.c. power to the transmit d.c. power to thesearchlight. searchlight.

Arc circuit:

Source of illumination..... Direct current, flowing Directcurrent, flowingthrough

through the high-intensity . the high-intensity carbons,

carbons, creates an ex- creates an extremely hottremely hot are and forms arc and forms a globule of

a globule of incandescent incandescent gas in thegas in the cratered tip of cratered tip of the positivethe positive carbon. The carbon. The incandescent

incandescent gas is the gas is the source of illumi-source of illumination. nation.

Positive carbon ......... 22" long x .633" (16 mm) 22" long x .633" (16 mm)diameter. diameter.

Negative carbon ......... 12" long x .434" (11 mm) 12" long x .434" (11 mm)

diameter. diameter.

Burning time ........... 1 hours (approx.) .......... 11 hours (approx.).

Arc current ............ 150 amps., d.c ............... 150 amps., d.c.

Arc voltage ........... 78 volts, d.ce................. 78 volts, d.c.

Lamp control mechanism:

Automatic control motive Feed motor .................. Mechanism motor.power.

Positive carbon.

Optical function ..... To maintain the crater of the To maintain the crater of the

positive carbon at the focal positive carbon at the focalcenter of the mirror by center of the mirror bymeans of the thermostat means of the thermostatcontrol, control.

64

SPERRY M1942 GENERAL ELECrRIC M1942

Lamp control mechanism-(contd.).

Operation .......... The positive carbon rotates The positive carbon rotatescontinuously and feeds for- continuously and feeds for-

ward when the ratchet is ward when the detent wheelheld stationary by the feed is held stationary by theplunger which is actuated positive detent which isby the positive feed magnet. actuated by the positive

This magnet is energized feed magnet. This magnet

by the thermostat contacts is energized by the thermo-or by the cam-operated stat contacts or by the semi-switch. automatic feed contacts.

The cam-operated switch is The semiautomatic feed con-

set for approximately one- tacts are set at MINIMUM.half the rate of burning.

Negative earbon.

Electrical function... To maintain the arc length To maintain the arce length

(distance between the tips (distance between the tips

of the positive carbon and of the positive carbon andthe negative carbon) at a the negative carbon) at aconstant value. Uses volt- constant value. Uses cur-

age control, Arc voltage rent control. Arc currentvaries directly as the are varies inversely as the are

length. length.

Operation ........... The negative feed magnet coil The are current regulator coil

is connected in parallel is connected in series with

with the are. The electro- the arc. The electromag-magnetic force in the coil, netic force in the coil, whichwhich is proportional to the is proportional to the arearc voltage, pulls the arma- current, pulls the armatureture in opposition to the in opposition to the arcarc length adjustment spring, current adjustment spring.This action positions the This action positions thenegative pawl guards, which current regulator contacts,control the forward or which in turn energize thebackward movement of the feed coil or the retract coilnegative carbon to main- of the negative drive clutch.tain a constant are voltage. The negative carbon is

moved backward or forwardby the action of this clutch,, maintaining. a constant arccurrent.

65

SPERRY M1942 GENERAL ELECrRIC M1942

Lamp control mechanism-

(contd.).

Semiautomatic control.... If the thermostat should fail, If the thermostat should fail,

adjust the- :am-operated adjust the positive semi-

switch by turning the semi- automatic feed contacts by

automatic positive feed screw turning the positive feed rate

134 turns toward SEMI to knob clockwise toward its

increase positive feed. If maximum feed position. Ifthis setting does not give this setting does not givecorrect rate, adjust to keep correct rate, adjust to keep

the positive carbon tip on the positive carbon tip on

the focal line of the ground- the focal line of the ground-

glas; finder. glass finder.

Manual control .......... Used in the event of the fail- Used in the event of the failure

ure of automatic control, of automatic control.

Positive carbon....... Rotate the positive carbon by Rotate the positive carbon by

rotating the positive rotation pushing in and rotating thehandwheel. Feed the posi- positive drive crank. Feedtive carbon forward and the positive carbon forwardmaintain thetipon the focal and maintain the tip on the

line of the ground-glass focal line of the ground-glass

finder by pushing the posi- finder by pushing in on posi-

live feed lever to-HAND tire feed button while theposition while the positive positive carbon is being

carbon is being rotated. rotated. Care should beCare should be taken not to taken not to overfeed the posi-

overfeed the' positive carbon tire carbon as it cannot be

as it cannot be retracted. retracted.

Negative carbon ........ Maintain the are voltage at Maintain the arc current at

78 volts, as read on the are 150 amperes, as read on the

voltmeter, by pushing the are ammeter, by pushingnegative feed lever to the in and turning the negative

HAND position and turn- drive crank in one direction

ing the negative feed knob or the other to feed or re-

one direction or the other tract the negative carbon.

to feed or retract the nega-tive carbon.

Dynamotor ............. .. Converts d.c. to a.c. for use Converts d.c. to a.c. for use

by all a.c. elements of the by all a.c. elements of the

searchlight equipment. searchlight equipment.

66

SPERRY M1942 GENERAL ELECTRIC M1942

Distant electric control (DEC):

Function............... I To provide a remote control To provide a remote control'

of the searchlight in azi- of the searchlight in azimuthmuth and elevation. and elevation.

Operation.

Automatic ........... i The DEC transfer switch offers The DEC transfer switch offersa choice between automatic a choice between automatic

and manual control. Auto- and manual control. Auto-

matic DEC is intended for matic DEC is intended fordirect control of the search- direct control of the search-light from a radar set, and light from a radar set, andis not normally used in sea- is not normally used in sea-coast artillery searchlight J coast artillery searchlight

operation. operation.

Manual . ....... . Manual DEC provides remote Manual DEC provides remote

control of the searchlight control of the searchlight

from the control station. from the control station.

DEC transnmitters WhentheDECtransferswitch When the DEC transfer switch

(control station). is set to MANUAL, azimuth is set to MANUAL, azimuth

and elevation synchro-trans- and elevation transmitters

formers (selsyns) located in (selsyns) located in the con-

the control unit are actu-' trol unit are actuated by the

ated by the control (ob- control (observer's) hand-server's) handwheels. They wheels. They are electri-

are electrically connected cally connected through thethrough the control cable control cable (300 feet long)

D E C r e c e i v e r e es (300 feet long) to azimuth to azimuth and elevation(searchlight). and elevation synchro-trans- control transformers. Two

formers. Two systems of systems of DEC transmitters

DEC transmitters and re- and receivers (33-speed and

ceivers (33-speed and 1- I-speed) are provided with

speed) are provided with the equipment. However,the equipment. However, only the 1-speed system is

only the 1-speed system is used in the manual DEC

used in the manual DEC system.system.

67

SPERRY Ml942 GENERAL ELECTRIC M11942

Distant electric control (DEC)-(contd.).

Power drive system... Displacement of the rotor of the DEC transmitter generates avoltage in the rotor of the DEC receiver. This error voltageis fed to the control grids of the vacuum tubes in the azimuthand eleration amplifiers. The output of the amplifiers excitesthe control fields of the desation and azimuth amplidynegenerators, which supply power to the drive motors whichmove the searchlight in azimuth and elevation. The rotorsof the DEC receivers are geared to the searchlight so thatmovement of the drum moves them an amount equal tothe movement of the transmitter rotors, restoring the systemto balance and eliminating error voltage.

Manual control:

Function ............... To point the searchlight if the To point the searchlight if theDEC system is inoperative. DEC system is inoperative.

Operation ............... Set the eleation drive clutch Put the devation dutch leverhandle to HAND DRIVE. and the azimuth clutch leverPlace the extended hand in the HAND position.controller in the socket on Place the extended handthe left trunnion arm next controller in the socket onto the elevation drive housing the right trunnion arm (partand engage it with the eie- of the elevation control box)vation gearing. The search- and engage it with the ele-light can be moved in vation gearing. The search-elevation by turning the light can be moved in ele-handwheel on the extended vation by turning the hand-hand controller. It can be wheel on the extended handmoved in azimuth by push- controller. It can be moveding on the extended hand in azimuth by pushing oncontroller in the direction the extended hand controllerin which it hi desired to in the direction in which itmove the searchlight. is desired to move the

searchlight.

Zero reader system .......... The zero reader system is designed for use in searchlight systemsusing a radar set for searchlight direction. It will notnormally be used by seacoast artillery searchlight installa-tions except a., a check on the operation of the DEC system.Seacoast units using radar for searchlight direction shouldrefer to technical manuals on searchlights and radar equip-ment for an explanation of the functioning of the zero readersystem.

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APPENDIX Ill--DRILL TABLE

SERVICE OF THE 60-INCH SEACOAST ARTILLERY SEARCHLIGHT

Details PREPARE FOR ACTION 1 EXAMINE EQIPMENr 2 REST STAND BY 4 SPREAD CONTRACT IN OUT

Light commander.... Supervises synchronizing and orient- When reports have been re- Checks with other members When other elements have .................................... Observes operation sf search- Checks that squad ising of searchlight set. Tests function- ceived from all members of the of the squad on the functioning reported ready, directs search- light and cheeks anyl evidence in "stand by" status.ing of DEC system. Checks communi- squad, reports to searchlight of elements of the searchlight light operator to report azimuth of improper functioning of anycation system. If light has been officer, "(Number of search- set. Makes sure that one or read from searchlight azimuth element. If extendedb hand con-removed from operating position as light) in order." both of the telephones is at- scale. Checks to see that DEC trol is being used, takes post 50a camouflage measure, supervises tended at all times, moves searchlight to azimuth of yards to the flank of the lightunloading and emplacement of light. target, if known. When squad and directs No. , by voice or

is ready, reports, "(Number of signal, in search and illumina-searchlight) standing by." tion of targets.

No. 1, control station Assists light commander in synchro- After checking performance Remains near the cootrol Takes post at azimuth and .................. .................. When searchlight s illumi- Uses DEC to keepoperator. nizing and orienting the searchlight of control station and DEC station, elevationhandwheels. Onorder nated, looks for a target in the light pointed at approx-

and control station. Tests functioning system, reports to light com- or signal from the light com- beam. If none is visile, tray- imate azimuth of targetof DEC by elevating and traversing mander, "Control station in mander, verifies that DEC crses 10 (5 either sie of as- (if known). Stands bythe light. If the light has been re- order." (Hand signal, "I am TRANSFER switch is at signed azimuth). If arget is for further orders.moved from operating position as a ready," may be used if eircunm- MANUAL and turns hasd- not picked up, waits fir orderscamouflage measure, assists in unload- stances pernmit.) wheels as directed to synehro- from searchlight officeq. Whening and emplacing light, nize light. Slews control unit target is illuminated, olls it

(if necessary) to azimuth re- necessary, keeping tie targetported by No. 2, then turns in the side of the beam next tolight by DEC to azimuth the using organization.of target (if known). If ex-

tended hand costrol is used,goes to searchlight to operatehand control.

No. 2, searchlight Assists light commander in synchro- After checking performance Turns off arc, if on. Closes Prepares searchlight for eper- Closes spread- Opens spread- When DEC has been hecked, Opens arc switch.operator. nizing and orienting searchlight and of searchlight circuits and spread-beam lenses, if open. ation. Before energizing DEC, beam lenses. beam lenses. closes ar switch. )bserves Stands by, ready to

control station. Checks electrical mechanisms, reports to light Remains in vicinity of the light. cheeks the synchronization of meters to make sure that proper strike arc on command.system at the searchlight. Inserts commander, "Searchlight in searchlight and control station voltage (78 vclts) and properfresh carbons in the lamp head and order." by observing the zero readers. current (150 ampn.) e beingverifies that spare carbons are avail- After checking synchronization, supplied to arc. Rec ons arcable. Verifies that extended hand reports, "Searchlight ready," at first break in opera on aftercontroller is available and ready for to light commander. When the positive earbon is halfuse. Tests light mechanism by strik- directed by the light com- burned (after about 45 minutesing arc.

5If light has been removed siander, reports, "(Number of of operation).

from operating position as a camnou- searchlight) azimuth (readingfiage measure, assists in unloadiig and of azimuth scale)." Opensemplaeing light. spread-beam lenses, unless

otherwise ordered.

No. 3, power plant Cheeks gasoline, oil, and water After checking gasoline, oil, Opens main power switch. Turns on power plant, ad- . ................................... Continues as at STND BY, Checks to see that

operator. supply, refilling if necessary. Starts and water supply, and testing Shuts down power plant and justs voltages to no-load value, checking to see that viltage is output voltage is atmotor and builds up voltage to re- the performance of the power renmains iii the imnlmediate vicil- closes main power switch, and at proper arc-load vue and proper control load

quired value. If light has been plant, reports, "Poweu plant is ity. reports or signals to light com- that amperage is corre value.removed from operating position as a order." mander, "Power plant ready."camouflage measure, assists in unload-ing and emplacing light.

£ This command alerts the squad at the beginning of a prot acted period of operation or drill. Usually given once daily, shortly before nightfall.-This command is usually given immediately following PsE RE POR ACTION.

If it is found that turning on the arc may reveal the sare light position to the enemy, the front of the light should be covered by a tarpaulin before turning on the are.

'This command is used to alert the squad when a target is nown or believed to be approaching the area assigned to the light. 158 Fort Monroe--31 Jul 45-4,100

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