[1]Patented Dec. 18, 1951 219'578@6,66 UNITED STATES PATENT OFFICE .2,578,666 GUN CONTP.OL AP.PAP.A-TUS Joseph L. Borden, Jr., Philadelphia, Pa. AppUcation January 31, 1946, $c@ri4l No. @644.648 23 Claims. (Cl. 89-41) (Granted under the act of March 3, 1883, as amended April 3'0, 1928; 370 @0.,G. 757.) Tlae invention described herein may be manufactured and used b.Y or,for the Government for governmei,tal purposes, with.out the payment to me of any royal'ty thereon. Lhis inventioii relates to a method of, and apparatus for airi'ling one or more guns to move them in train and eleva@.ion in 'Lhe,rranner necessary to continuously engage a moviiig tgrget w-hich may be vis4lble or invisible from the ggn location. 10 At the present time, guns of large caliber are ai-rr-ed at moving targets such as aircraft or surface shias, on the basis of data supp'lied by a gun fire di_- rector or coniputer. Such directors are consbru@- ted to re@.eive various in]yat datla @such 15 as the present range, angul@a@@- rates of,mover@ient of the target i@'i a7,:lmut-h and elevation, altitude, etc., and to supply as outputs, the coy-itinuously chan@ing azimuthan' elevation angles and fuse settin@s to which thegun or guns and projectiles 20 should be adjusted in order to hit t@ie target. The guns Pre usually located at some di-stance from t@lie director and it is customaiy to supply the director outputs or computed data to the gidns by telepho-4ie or,by t@-loriietric transmission 25 systc-,-ns. case 'tlie necessary inforrnation is conveyed by tele-o' ioiie, tl-,ere is an appreciable time lag of ap.oroxi.r4iately 1.5 sep-on.@s betveen the time the iii,lormat ,ion is receive' at tl,.e.guris.aiid the time 30 sui3h informa,,,tlo-.-@ can be set into the guns :and the guns fred. Furl@4-iermore, su@,h syster@is @involve the s.-rious possibilily of. errors caused by i.neorre,,,t,r e:3etitio-Li of ei-rector values.by the:persor.nel at tl--,e d4.rector, or misunderstanding on 35 th-= part. of the persoimel at the @guns. in even-t the data are suopl-.ed by telemetric. tre,nsini ssion syste-.-ns, the values of.elevation,and azimuth Pre read oi-i on repeaters at the @guns nents and used P-s ti-.e for m-qnual adjustr 40 of the .-uns. !'.his may be .Ione,by conventional "inatch th,-: sy-,,teriis wh6rein the gun trainer, for exai---P",e, operates the @trainin- handwheel of b@s guii until-a pointer controlled thereby matches, or is in a predeterir-.ined position 45 wi-t-l-i respect to, a poi-nter @)ctuated by the@trail'i repeater. Or, i-n other systems, @the train and elevat4.oii repeater , s -at eac-h gun ma@j directly conl,,rc,l a so-arr@e of power, @throu.ah well-knmvii servo-motor or follow-ups, to auto-rnatically cause 50 the gun to be elevated-and tr,-.ined in accordance wit'-ri computat-ior,.s supplieci 'oy t',he director. In such systems, there -is eithei, the pos@ibility of a lag @iiitroduced @betweeri-,d-ie -ti@ile@@the; p-ointer and trainer notice a inc--veinent @on the @'directorcon- 55 .2 trolled pointers and the time they are able to match said movement by actuation of their respective hand wheels; or a time lag is introduced by -mechanical and electrical adiiistments and inertia of the fo.Uow-up controls. The output values of angles ol t,.he director are, of course, @-@vith reference to a predetermined Plane and reference line. T-hat is to say, for example, its oukout elevation angle will be with reference to a horizontal plane and its output azimuth angle -v@ill be with reference to a horizontal line @having apreselected direction such as north-south. In order that the gun may be Properly aimed, the angular values@of elevation pnd train @im arted thereto @p must be measured from a plane and a hne that are parallel to those,-of the director. T-his.,requires that, prior to the commencement of firing, the gun and its director be coordinated@- -On the other hand, any subsidence settling or @shifting @of @the gun during fir-iiig, will, alter the-reference plane @and/or ref erence line of -the gun with relation to the director so, that, as a result, the, gun will not - be correctly aimed when -subsidence takes place with th.elprior art.systems just discussed. It is.therefore :an @object of my invention to provide, a system: of training @and elevating a gun or guns by information supplied by @a remote director and wherein the foregoing drawbacks and:possibilities.of error are obviated. object @is @to --orovide a method of and apparatus .@for correctly aiming a gun wherein the gun is smoothly and continuously moved in train and,-eleva;ion -so -as to at all times remain in substantia@lly correct firing position and may continuously enga@e the target. Another -object is to provide a method of, and apnaretus @ for @ainiing a gun - whe@-ein the tiine between s'nots may be very appreciably reduced over @that required by present comparable systems, Nvhile at the sariie time, effecting a very I substant,,al increase in accuracy and percentage of hitslpon the moving target. A :Still:further object is @to -provide a method of, and apparatus - for @giming a glii or gvns i wherein the @possibility of -er-rors that in'ght otherwise be caused by settling or displace.-nent of the gun-di-le to its o-%vnweight, recoil in firing, 6te., is avoicled and t-lie,giin is, at all times, si.,ioothly and cor-r-ertly aimed solely:uoon the bas"s of dt'a supplied by the director. A further object is @to provide an iniproved system of gun aiming wherein the gun is -continuously trained to retain a silght carried -t'-qereby
[2]3 with its line of sight directed upon a fixed reference stake or dummy target as the line of sight is auto,-natically moved in azimuth relatively to the gun at a rate automatically effected and controlled by the director. Another object is to provide a system of aiming a gun where4.n the elevation quadrant is smoothly and automatically pivoted relatively to the gun so that the correct elevation may be obtained by the simple act of continuously i o changing the elevation of the gun and quadrant as a unit, to maintain centered, the bubble or other indicating element of a longitudinal level carried by said quadrant. A still further object is to provide an alterna- ) 5 tive and satisfactory means for training the gun when, for any reason, the fixed reference stake becomes obscured. Another object is to provide improved elevation and azimuth receivers whereby increased 20 accuracy of reception of signals from the director is assured. Other objects and advantages of the invention will become apparent as the description proceeds. 25 In the drawings: Figure I is a plan view shbwing diagrammatically a typical arrangement of gun, director, aiming point and target. Mgure 2 is an elevation of the right-hand side 30 of the gun showing the. manner in which the elevation quadrant and gun are rotated in opposite directions to maintain the gun continuously at proper elevation. Figure 3 is a schematic view of a portion of the 35 electrical connections between the various units utilized in my invention and showing how a battery of four guns may be simultaneously controlled from a single director. Figure 4 is a perspective view of a portion of 40 the left side of a 155 mm. gun equipped for control by apparatus and in accordance with the method of my invention and showing more particularly the azimuth or train control. Mgure 5 is a perspective view showing a por45 tion of the right hand or elevation side of a 155 ram. gun equipped for control in accordance with the apparatus and method forming the subject matter of my invention. 1,0 Figure 6 is a schematic view of the electrical , connections for azimuth control between the di-id gun and showing the mechanical rector aT drive from the servo-motor to the revoluble head of the azimuth sight and the rotor of the re,@ i) ceiver at the gun. This figure also shows the ' indicator which may be used for training when the aiming stake becomes obscured. 14gure 6A is a schematic view of the electrical connections from the director to the elevation (,o side of the gun and showing the manner in which the servo-motor is mechanically connected to drive the elevation quadrant of the gun and the elevation receiver. F-igure 7 is a wiring diagram showing one of b5 . the hook-ups by which a transmitter at the director controls a respective servo-motor at the gun. Figure 8 is a perspective view showing the synchronizer of the azimuth control which acts to 70 prevent ambiguity in the angular values repeated by the fine azimuth receiver and servomotor controlled thereby. Figure 9 is a detail view of the contacts of the synchronizer.. 7@@, 2,578,666 Principles of operation Referring to Figure 1, the numeral I identifies a gun emplacement or base on which a rotatable gun carriage or platform 2 is rotatable about a central vertical axis normal to the plane of the paper. Teeth 3 are formed on the periphery of platform 2 and with which a worm 4 is adapted to mesh. The worm is journaled on base I on a horizontal axis, by means of a shaft 5 and bearing 6. A handwheel 7 is secured to shaft 5 and is in a position such that it may be turned by an operator while looking into the eye-piece 8 of azimuth telescope 9. This telescope is of the well-known panoramic type including an objective I I rotatable relatively to the gun about a normal vertical axis and having optical parts by which the image of objects in the line of sight determi-ned by said objective, is deflected to a horizontally-positioned ocular. A gear 10 is connected to rotate objective I I about its vertical axis. As it is so rotated, to an observer looking in ocular 8, objects appear to move laterally across the field of view in a direction depending upon the direction of rotation of objective II. A worm 12 is in mesh with gear I 0 and is adapted to be driven by a servo-motor IS that is electrically connected with, and controlled by, a director 14, through electrical circuit connections 15. This director has means such as sights or radar, for determining a line IO between director 14 and target T which is assumed to be traveling in the direction indicated by the arrow. The gun 17 is journaled for elevation about a normally horizontal axis, by trunnions I a supported in bearings in standards 19 fixed to platform 2. See Figure 2. Elevation is effected by an arcuate rack 20 attached to the gun cradle 21 and in mesh with a worm 22 journaled in standards 19 and adapted for actuation by a handwheel 23. A servomotor 24 similar to inotor 13, is carried by cradle 21 and is connected to, and controlled by, director 14, through electrical cable 25. This motor has a worm 26 on its shaft, in mesh with the arcuate rack of an elevation quadrant 27 having a bubble tube level 28, or other level indicating means supported thereon. Quadrant 27 is supported on cradle 21 for pivotal moveinent about an axis parallel to the axis of trunnions 18. In operation, a dummy target or reference stake 29 is provided at any convenient position, eas4ly observable from the gun, and the director and gun are coordinated so that the director output or predicted angle in azimuth, will be with reference to a base line that is parallel to the line of sight form telescope 9 to stake 29, while the director output or predicted angle in elevation, as well as the angle of gun elevation, will be with reference to a horizontal plane. Electrical connectibns are made between the gun and director, and, when a target is sighted, the director is so moved as to maintain line 16 directed thereon, either by direct sighting, radar, sound locators, or other known means. Other required values such as range, are introduced into tlie director which then supplies data in the form of predicted elevation and azimuth angles at which the gun should be adjusted in order to hit the target. It is assumed that the target is moving, so that the aforesaid output angles are continuously changing in accordance with the target's speed and heading. Signals proportional to director output or prediction angle in azimuth are transmitteo over cables I 5 to motor 13 so that the
[3]latter is operated ih accordance with the, rate of change of said prediction angle. The motor then acts to rotate abjective 9 about its vertical axis in accordance with the aforesaid rate of change in the direction opposite to the direction in which 5 the gun must be moved. To the gun trainer, looking into ocular 8, stake 29 appears to move laterally away from the vertical cross hair of tl-ie telescope. He then egntinuously adjusts hand wheel 7 to maiiita,@,,i 'the cross hair s,,,,perposed@ 10 over a selected -point of the target ancl, in -so doing, causes the gun to -be'traversed at the-proper rate predicted by the director. At the same time, signals proportional to predicted elevation aiigle are transmit'-ed from di- 15 rector 14, over cable 25, to dtive motor 24 iii accordance with such signais. The motor is operated in a direction such that sector 27 will be rotated in the direction opposi-te to the nece-@sary direction of elevation or depression of the gun- 20 Thus, for example, -if the elevation of gun 17 should increase, sector 27 will be rotated clockwise as seen in F-igil-re 2. The gun pointer, noting the bubble of level 28 to move off center to the left, will rotate his hand-wheel 23 to keep the 25 bubble at all times centered. In this manner the gun is continuously properly aimed so that it may be fired at any time. Furthermore, shifting or subsidence of the gun itself has no effec@t, upon the accuracy of fire since all 30 angles are measured wi-th reference to a line and a plane that are fixed with reference to space external of the gun and its support. For example, suppose that the gun shifts about a vertical axis or subsides in a vertical plane through the gun 35 bore. Opcration of hand @vheel 1 i-n the zran,.ier necessary to restore the line oi: si-.ht '@-o the stake, and of hand wheel 23 to centralize the bubble, completely corrects for the errors in airn that would otherwise have been introduced. These 40 errors would have remained uncorrected in prior art systems where the gun is moved simply to match one pointer with another, controlled in position by the director. Director-gun ezectrical connections 4 At Figure 3, I have shown a schematic layout of the connections between the director and the gun or guns. In this figure, the director or predictor 14 is coupled to a inain junction box 30 by r, t, cable connectors 31 and 32, one of which supplies current to the predictor 14 from a generator unit 33 connected to box 30 by a connecto-r 34. Box 30 is provided with outlets for connectors 35 and 36. Connector 35 leads to an extension junction 5r) box 37 having receptacles for a.pair of connectors 38 and 39, each of which may lead to a respective gun junction box, only one of which, 40, is shown upon the figure. It will beunderstood that consimilar to 37 so that from one to four guns, as desired, rnay be controlled from a single director. Box 4D has a 19-hole receptacle for a connector 41, leading to an azimuth amplifier 43 which, in turn, is connected by cable 44 to the aziinuth synchro-transformer and servo-motor represented at 65 45. These parts will be subsequently described in detail. For the present, it is sufficient to explain that the azimuth servo-motor is connected, through reduc'tion gearing, to drive the rotatable 7( head of the panoramic telescope carried by the gun for movement in train therewith. Likewise box 40 has a multi-pole receptacle for a,connector 42 extending to an elevatibn am@lifier 46 which is connected by cable 47 to the cgsing U'for thd elevation quadfaiit syhe, ro- rans6@ former and servo-M otoi. -The box:40, connectors 41 alnd 42 and amplifiers 43 and 46, are all carr@ed by the @gu,.i, while extension junct@on boxes 37, con--aectors 35, 3 , 8, init 33 and main junction box 30, may be mouiited upon a power slipply unit such as a truck or trailer. The connectors 33, 39, etc., may have ELny length up to about 400 yards. By the connections described one director and generathr unit may supply data and power to control four relatively remotely positioned guns. T h e o n - c a r i i a g e m o u n t i n g Figures 4 and 5 show the invention as applied to a standard 155 mm. gun or howitzer. Referring to Figure 4, the gun is mounted upon a bottom carriage to which a traversing are 50 is secured. A top carriage assembly 51 is mounted upon the bottom carriage, for,pivotal movement a.bout a normally vertical axis with which are 5P, i,,, boncentric. Top carri.age assembly 51 includes bearings 52 within which trunnions are held by bearing caps 54. The trunnion bearings are he'id iii place by plates 53. These caps 54 have integral upward extensions 55 to which the rear ends of respective equilibrators 56 are pivoted at 57'. The purpose of the equilibrators is to balance the weight of the gun so that it can be elevated witliout difficulty. The gun barrel 57 is mouw@ed for sliding movement in a direction parallel to its bore, upcn a crad!eandrecoilmechanism,69. SaidmecharLism is, i-n turn, fixed to and:supported by truniiions 1.@S. Training of the gun is effected by a trainer sitting in seat 58 and turning hand wheels @59 and 60 by means of handl-'s 61 and 62. Turning of these handles effects rota-Lion of a pinion 63, in i-nesh with arcuate rack 50, through a mechanical drive shown clearly at Figure 6, and comprising bevel,pinions 105, shaft 106, bevel gears 107, shaft 1 08, worm IO 9, gear I IO, and shaft I I I to which traverse pinion 03 is keyed. This drive is e-nclosed within housings 64, 65 and 66, connected by tubular conneciions 67 and 68, as shown in Figure 4. The panoramic sight is indicated generally at 70 and is carried upon a mount 71 havi-ng a collar 72.journaled upon an inner collar 73 which, in turn, is carried by a support 74 in alignraent v%7-."t'-q the tmin4@oii @.,xis of tlyc- gun ard defliing an axis that is adadted.to be maintained parallel to the bore of the-gun. Cross-leveling mechanism 75 is provided -L-o rotate the inount 71 about the aforesaid axis to effect corrections for errors in aim otherwise introduced by tilt of the trunnion axis in the -manner well known in the art. The mou7-it 71 has an upstgfldi.-Lig socket TO to receive and @support the sight proper. This sight consists of a vertical tube 77 received within the so,-,ket 76, an eye-piece or ocular 77' projecting an or p-?,n.ora.-gic port@on 79 inounted at the top of tube 77,for rotatioii through 360' of angular rqovement about a normally vertical axis. Rotation of objective 79,is effected by a shaft 80 which, in accordance wi,@h *ell known construction, carries a worm in mesh wi4uh a gear attached ta objective 7 0. A casing 81 is fixedly mounted upon a bracket 82 carried by the gun trunnion support and, as shol@vri scheiratically in lligure 6 ' has a shaft 83 in alignment with shaft 80 and adjustably connected -Lhereto through a coupling@84. By rotation@ of knobs 86 of this coupling, r6lative rotation betv,7een shdfts 80 aiid 83 may be effected. c asing: @81 -iias-windowi@'86 and;185-through'whiell nector 36 may lead to an extension junction box 6(1; fror@i tube 77 through a-slot -78 in socket @76, and
[4]17 indicator dials 87, 88 and 89, Figure 6, may be observed. The purpose of these dials will be subsequently described. Covers for receptacles for the various electrical connections, are indicated at 90 and 91. The azimuth servo amplifier 43 is g mounted on top carriage 51. See Figure 4. A milliammeter 163, Figure 6, may be observed througli a window 94 at the top of the amplifier. An azimuth indica,bor is identified at 93. Cable 49 effects electrical connection between amplifier'lu 4 3 and servo-motor casing 8 1. Turning now to the right hand, or elevation side o@4 the gun, an elevation hand wheel 95 (Figure 5) is keyed to a shaft 96' journaled in the top carriage asse @mbly. Reduction gearing is 1,,3 inounted within a casing 96 and has its input geared to shaft 96' and its output keyed to a pinion, not shown, in mesh with elevation are 97. Are 9 7 is bolted to the lower surface of cradle assembly 69 and is, of course, concentric of the 20 t-runnion axis 6o that the gun may be elevated or depressed by turning of hand wheel 95 in the direction in which it is desired to rotate the gun. The trails for steadying and stabilizing the gun when in firing position, are identified at 98 and 99. 25 The elevation quadrant, synchro-transformer and elevation servo 48 are mounted within a casing carried by top carriage assembly 5 1. A level in the form of a bubble tube IO i is carried by a shaft, not shown projecting from casing 100. 3,) This shaft is parallel to the 'Lrunnion axis of the gun and level IO 1 is normal thereto so that the longitudinal axis of the bubble tube lies in a vertical plane parallel to a vertical plane through the axis of the gun bore. As the elevation servo- -,5 n@ otor is rotated under the control of signals from the director, level iOl is turned in the aforesaid vertical plane at a rate equal and opposite to the rate of gun elevation necessary to keep the gun cont4,n,,iously correctly elevated. The operator 4,) then ' ,uriis hand wheel 95 to maintain the bubble of level I 0 1 centered, and in so doing contiiiuously maintains the gun at the elevation computed by the director. A micromeiler scale and actuating knob are 45 identified at 103 for hand operation of level when desired or when the dir6ctor is out of operation. Numeral 104 indicates the removable cover for a ready signal lamp. The elevation amplifier 46 is fixed to the top carriage 51 and is electrically con- 50 nected with the elevation quadrant 48 by cable 47, as described in connection with Figure 3. '@'he azimuth sight cont?-ol Referring now to Figure 6, dotted line 14a indi- 5 ;3 cates the azimuth portion of director 14. This director may be a standard instrument such as t',ie Army's l%jl8N or M8P. It is sufficient to explain, therefore, that the final predicted azimuth output of the director results in the rotation of 6., @) the rotor I 1 2 of a coarse transmitter I 1 3 and t-he proportional rotation of rotor If 4 of a fine transmitter 115. These transmitters are conventional "Selsyns" or "Autosyns.1' The rotors are mechanically connected in a 36:1 ratio such that (15 114 makes 36 rotatioiis for each rotation of 112. Graduated dials 116 and 117 are connected to the respective rotors to indicate the rotations thereof. Rotors If 2 and 1 14 as well as all others subsequently described, are supplied over con- 7(@ ductors 34 with standard 115 volt, 60 cycle A. C. current from unit 33. Transmitter 113 has field coils 118 Y-connected over the cables in ;connectors 31, 35, 38, 4 i and 44, Figure 3, to the field coils 121 of coarse repeater.120, having a rotor 75 2,5783666 8 winding 122 mounted upon a shaft 123. Dial 89 is secured to this shaft. Similarly, the field coils 119 of transmitter 115 arey-connectedtothefieid coils 125 of fine repeater 124. The rotor 126 of repeater 124 is :connected to shaft 83, previously mentioned. In an ordinary Selsyn hook-up, rotation of rotor 114, for example, would cause a like rotation of the field induced in field coils 119. This field rotation would be repeated by receiver coils 125 to thereby effect a rotation of repeater rotor 126 until the field thereof is parallel to the new position of the resultant field of coils 125. In my invention, the repeater rotors 122 and 126 are rotated Ln synchronism with their respective transmitter rotors I 1 2 and I i 4, by a motor 121 having one phase 128 continuously energized from source 33, by way of connections subsequently traced, and a second phase 129 adapted to be energized by and upon rotation of the resultant field of field coils 125, relatively to rotor 126. Motor 127 therefore rotates only during such times as its phase 129 is energized; and its rotation ceases as soon as rotor 126 is aligned with the new position of the field of coils 125. The manner in which precise energization of phase 129 is effected will be subsequently described in connection with Figure 7. Rotation of rotor 130 of motor 127 drives shaft 83 and fine repeater rotor 126, through a 250:1 reduction gear train indicated generally by the numeral 13 1. At 2400 R. P. M. for motor 127, a maximum tracking rate of 1.6'/see. is provided. The final drive of train 131 is a gear 132 fixed to shaft 83. This shaft also has fixed thereon, a pinion 133 and a gear 134. Gear 134 meshes with a gear 135 on shaft 136. Fine indicator dial 88 is fixed to shaft 136. Since 134 and 135 are of equal diameter, while shaft 83 rotates 36 times for each 3601 rotation of telescope head or objective 79, dial 88 rotates once for each 10' rotation of the line of sight. A 36:1 reduction gearing is indicated at 137, between fine dial 88 and coarse dial 87 so that the latter rotates once for each 360, rotation of the telescope head. As previously explained, dials 87 and 08 are observable through window 185 in casing 8 1. The azimuth and elevation synchronz'zers The two synchronizers are essentially alike and differ only in the gear ratios by which they are connected to the respective fine repeaters. Hence a description of the azimuth synchronizer, -as illustrated in Figures 6, 7 and 8, will suffice. It has previously been explained tha the azimuth repeater shaft 83 rotates 36 tirnes for each 360' rotation of telescope head. This reduced ratio provides a high degree of accuracy but, standing alone, might introduce ambiguity because of 36 possible positions in which shaft 83 and rotor 126 would be in step with transmitter 114. The coarse transmitter 113 and its repeater 120 are provided to avoid this ambiguity. As previously stated, rotors II 4 and I i 2 in the director, are connected in 36:1 relation by mechanism not shown. iiikewise shaft 83 is connected with shaft 200 of the synchronizer bY a 1:36 reducing connection that includes pinion 133 meshing with gear 201 fixed with pinion 203 on countershaft 202. Pinion 203 meshes with a gear 204 on shaft 200. As more clearly shown at Figure 8, shaft 200 has thereon a sleeve 208 attached thereto, and on which are mounted slip rings 2 5, an The sleev,e also has a radially and axially-extend-
[5]2,b78,P,66 ; 9 ing arm 209 on which are mounted a Pair of coiitacts 210 and 211 spaced in a plane normal to, and circumferentially of, the axis of shaft 209 and shaft 123 coaxial with shaft 200. A suitable @earing support, not shown, is provided for tlie 5 end of shaft 193, remote from repeater 120. Rotor 122 of coarse azimuth receiver 120, is connected with shaft 123. A contact elem. ent 213 is journaled in a bearing 214, coaxially of shafts 290 and 123. This eleni,-.iit coii'lorises a disc hav10 ing an i-.qternal heart-shaped cain 2 1 5 and a projection 216 having contacts 217 and 218 interposed between and adapted to engage contacts 2 1 0 and 21 1, for respectively opposite directions of relative rotation between element 213 and 15 shaft 200. The proportions ore such that a rotation of elertiert 213 about 3' i-n e.-Lther direction relptivel7l, to shelft 20n., restil't's in i-,he clof,!,,ire of a r6spective pair of contacts. A yiel.ding, self-centrp..@izing connection is, af20 forded between shaft 123 and element 213 by the cam 210, in conjunction with a roller 219 urged radial-iy outwardly into contact with +@he cam surface by a sl,3ring 220. This yielding connectiot-i has been omitted upon Figure 6 to a7,roid 25 confusion. Conductors 221 and 222 lead from contacts 210 and 211 to sli-o rings 205 and 206, respectively, ivhile a third conductor 223 connects both contacts 2 1 7 and 2 18 with slip ring 2 0 7. By the foregoing construction, contact is made at 2 1 0 30 or 211 whenever shaft 123, under the control of coarse repeater 120, rotates relatively to shaft 200 by a mini-mum of 3' in either di.rection. Thus shaft 2 0 0 rotates in 1: I ratio with telescope head or objective 79. The contacts 210 and 211 act 35 to control the ampli--ier 43 and, hence, motor 127, through connections that will be subsequently traced. Si-nee contact is made at 210 or 211 whenever the coarse repeater is out of step by a minrqum o-f 31, any ambiguity that might other40 ,@&,ise be present in the position of shaft 83, is avoided aiid said shaft is kept within the 10' sector necessary to accuratejy reproduce the predicted azimuth of the director. The elevation Sy-Tichronizer Ls identified by the numerals 297 to 45 3L'3, inclusive, Fi.@Lire 6A, and in view of the -'act that it i-s identical in construction and operation vzith the azimuth synchronizer, it is deemed unnecessary to describe it in detail. The azignitth indicator 50 Occasiors arise in combat @v'-here it is necessary to lositio-, the guns ).n azimuth without the ise o,-'@ tbe az@@Miith telescope. For use in such situations I have provided an azimuth i-ndicator shown scherr@a'tically in IN-'gure 6, v.7here it will be r@o'ued that a repeater or synchronous transformer i38, has field co;@ls 139 Y-conn.ected over cable 141, with the correspolid,iiig coils of tr,,tns60 initter 115. The rotor 140 of repeater 138 is iroi,ip-ted upon a shaft 142 having thereon a gear 143 aild a fine di-al 144. A 36 to I redliction gearing, indi-cated at 146, is interrosed between fine dial il-q P,,D-d a coarse dial 145. Since the 65 ,ield e-f --oilc- ! 3, @3 :otites i-n synchroni-.tm with that of fine transmi'tter I 13, rotation of rotor 140 to maintain its coil in alignm,--@it v@ith the resultant i9-eld olf co4.ls 139 will resu,t in synchronous rotatio,ii of dials 1,1@ and f45 witl, those of dials 1'0 08 at-id 87, respectively. Gear I @;3 is co-nnected to one side 148 of a di,'-Perential 147 having its center cot-inected to a shaft fr,,g conliected with g(@.qr flig, and hence, 10 gear ratios are such that the gun is traversed or trained through lo' for each rotation of dial 144 and in 1:1 ratio w-Lth dial 145. '3'he second side f@.9 of the differeritial Is adapted to be operal@ed by i knob l@7,1 throiigh a connection including shafb 352, recluc,@ioii geors 153, shaft 154 and reduction gears i 51.@ and 155. '@@he overall rediiction ratio may be 1: 12 so that fine knob 151. is rotated twelve times for each rotation of gear 156, Gear 156 is mounted upon a sbaft 157 to which a coarse knob 158 is attached whereby the angular adjustments effectled by knob 151 may be determiiied. Shaft 152@ is norrrally lo.-ked ,igiinst rotation by a releasable detent 159 of any suit@tble construction. Rotor 14 0 is connected by conductors IC 0, with a phase detectinv circuit 161 haii-@ng an output 162 connected to co--,,itrol an error meter or i--(iilliammeter 163. T"ie connections are such that when director rot@,,r 114 is rotated throti.-h a certain angle, t-he field induced by coils 139 i-s corr,-spondingly rotated and moved from its previous position of alignment with tlie electrical axis of rotor 140. As a result of this lack of alignment, an alternating potential is induced in rotor 140 whose phase clepends upon the direction of rotation of rotor 114. This 1)otential is then detected as to phase in circuit 161 and the out-,out applied to meter 163 to deilect indicator 184 in one direction or the other, depending up-on the d;@rection of rotation of rotor II 4. Thus any deflection of indi-cator 104 info@ms the trainer tl-iat the guri is not at the proper a7imuth angle predicted by the director, and he may briiig about agreement by operating his hand wheels 59 and 60 until pointer 164 is returned to null or zero position. The connections are such that a deflection of 164 to the right requ,ires a training movement of the gun to the right. Circuit 161 is mounted withi-yi amplifter housing 43 ., Figure 4, and meter 163 is positioned to be viewed through window 94. In i-iorm,,tl operation, the trainer observes the aiming point 19 through sight 7e and effects the training movement indicated thereby. , Sbould the point 29 become obscured, he has only to shift h,'-,'3 eye to rneter 163 and continue training in accordance with the indicatiotis thereof. The use of meter 163, is essentially less accurate than sightiiig on aiming point 29 since its accuracy depends upon the stability of the gun carriage and does iiot correct for azimuth errors introdiiced by shiftirl-g of the gup.. it does, however, provide a means for eff-ecting satisfactory training under more or less emergency conditions. The drive to side 149 of differeiitial 147 from knob 151 is normally locked by detent 159 so that the drive from htnd wheels 59 and 60 to rotor 140, proceeds directly through the differential. When the trails 98 and 99 of the gun are shi'Lted to cover a different sector of fire, a new horizonta), base or ref.erence line is, in eftect, estaLIished. Thus, after the gun and director are a,-@Jji@sted i,,,ith their base or@,eference li.nes in r,,,arallelisni, liand @64 %,ill ordin rily not be centered. Centralization caii then be effected by releasing detent 15R and turniiig knob 158 @intil substantial centralizat@on of hand 164 is Produced,. ExpQt centralization can then be eff ected by adju@t,.,iient through -Fl-,ie knob 15 1, after which shaft 152 is agoin lo-,ked by detent I 59. Aitf-Ir tbis ad ,justme@- it the meter 163 inay @e used for control of the azimutl-ial position of with, shaft Ill and traversing p-inipxx 63. The @'5 the qun in the new sectoy.
[6]The elevation qitadrant control Referring more p,articularly to Mgure 6A, the elevation portion of the director is indicated by the dotted lines 14b'and includes a fine transmitter 165 having a rotor 166 and field coils 167 together with an indicator dial I 6 8 connected f o; rotation with rotor 166. A coarse elevation transmitter is indicated at 169 and includes a rotor 170, field coils 171 and an indicator 172 connected for rotation with the rotor 170. Both rotors 166 and 170 are supplied with alternating potential from source 33. The fine elevation receiver is indicated ,3,t 175 and includes rotor 173 and field coils 174 Yconnected with transmitter coils 167 in the @onven'L,ioiial manner. The coarse r,- peater 176 eludes a rotor 177 and fleld coils 178 The rotor of fine repeater 175, is connected 'for rotatioxi with a shaft 179. An adjustable couplin- 180 connects shaft i79 to a shaft 181, whi@h, in turn, drives elevation quadrant 48 through gearing 182. Access to this coupling may be had by removing cap 295, Flgure 5. It may be adjusted to effect relative rotation betweeii shafts 179 and 18 1, or to entirely disconnect s,,iid shafts. When disconnected, data may be introduced manually into the quadrant. A two-phase motor 183 has one phase 104 continuously energized and a second phase 183 connected for energization under the control of amplifier 46 whenever the field of rotor 173 and the resultant field of coils 175 are out of parallelism so that a potential is induced in the coils of rotor 173. Motor 183,drives shaft 179 through a reduction gear train 188 having a final gear 189 fixed to said shaft. The over-all ratio may be such that rotor 187 rotates about 1300 times for each rotation of shaft 179 and rotor 173. Shaft 179 also has secured thereto a pinion ISO constituting a part of the synchronizer, subsequently to be described, and a gear 191 in mesh with a gear 192 mounted upon shaft 193. A fine elevation indicator drum 194 is fixed to shaft 193. A 16:1 reduction gearing is identified at 195 through which a coarse elevation indicator drum 196 is driven. In the installation disclosed, these drums are located at the lower left of quadrant 48, as viewed in Figure 5. The over-all gear ratios are such that the elevation quadrant rotates 100 mils per revolution of drum 194 and 1600 mils per revolution of drum 196. Director rotors 166 and 170 are connected by mechanism not shown, for rota-tion in 16:1 relation. When rotor 166 is moved by the director mechanism in accordance with predicted values of gun elevation, the resulting rotation of field induced in coils 167 is repeated by coils 174. The resultant field of coils 174 now induces a potential in rotor 173 which is amplified in amdlifier 46 and applied to phase 186 of motor 183 which now turns at high speed to drive shaft 179 and rotor 173 until the latter is in its previous relation with the field of coils 174. V,7hen this relation is restored, no potential is induced in the coils of rotor 173 phase 186 is de-energized and rotation of motor 183 ceases. The amplifters Closure of the azimuth synchronizer circuits through contacts 2 1 0 or 2 1 1, results in the application of a relatively large voltage to the input of the amplifier. The phase of the voltage thus applied varies according to whether contact is made at 2 1 0 or 21 1. Referring to Figures 6 and 7, 225 and 226 represent input conductor co 4 2,578,666 nected to generator unit 33 shown at Figure 6, and supplying the prim. ary 228 of transformer 2 2 7 having secondary windings including 2 2 9 and 230. Either of windings 229 and 230 is adapted to supply the priinary 232 of synchronizer transformer 231 depending upon whether contact is closed at 2 1 0 or 2 i 1. Normally, that is, Nvith con'acts 210 and 211 open, primary 232 of amplifier transformer 231, lo is supplied from fine transmitter rotor 126 over conductors 234 and 235, the former having therein a resistor 242 of I K. and 10 watts power capacity. Should the relative rotation between shafts 123 and 200 exceed 3' in one direction, contact is 15 made in the synchronizer at 2 1 0 and the eirei-lit then proceeds by conductor 221 transformer secondary 229, conductor 233, primary 232, and return line @23 to the synchronizer. In case contact is made at 2 i I the circuit proceeds by way 2( of conductor 222, transformer secondary 230, conductor 233, primary 232, and return 223, to the synchronizer. In both cases, a signal of approximately 20 volts is applied to primary 232. This voltage while 25 modulated by the voltage induced in rotor 126, is sufficiently large so that an error signal will always be applied to -Drimary 232 irrespective of whether or not the signal from rotbr 126 is in or <)ut of phase with the signal from transformer 227. The secondary 236 of transformer 231 is cotinected over lines 23T and 238 to the grids of Et dual triode 239, which may be a 6SL7 or similar type of tube. Connection is made through capacitors 240 and 241 of 0.03 mf. each. The plates of tube 239 are connected with the p@-imary 243 of a transformer 244, through a fixed resistor 245 having a value of 10 K. and a variable resistor 246 having a maximum value of 20 X,, '@l The center tap of primary 243 is grounded through a capacitor 292 of 0.25 mf. and a resistor 293 of 25 K. Resistor 246 is @-nade variable because it is difficult to find a dual triode tube whose eleci@rical characteristics are ide@itical in botli '15 sections. Any diff eren-.e bet@,veen tlie tvio seotions, as well as other possible unsymitettical circuit constants, can be balanced out by adjustment of this resistor until the voltage drop, across@ the mid-point of winding 243 and the t,@vo plate terminals, are equal. A 350-volt winding 250 of transformer 227, supplies plate voltage for tube 239 over connections that will subsequetitly be traced a@nd that include a resistor 251 of 20 K. connected in line 252 leading from one terrningl of winding 260 to the common cathode terminett 253 of tube 239. Resistor 251 provides a, voltage drop giving an additional component of grid biag to thus afford wide pulses of plate current without grid current. A capacitor 247 of 0.02 mf. is con'@1) nected between the plate terminals. Now consider a condition in which there is no error signal applied to winding 232. During that h,@llf of the cycle when the plates of tube 239 are positive with respect to the cathodes equal f, 5 plate currents will flow in the tube sections and the resulting voltage drops across the two halves of the transformer winding 243 will be equal at each instant so that the net drop across the winding will be zero and no current will flow., 70 Consider that an error signal is applied to primary winding 232 of transformer 231, through. closure of contacts in the synchronizer and that' the phase of this error signal is such that the. induced voltage in the left half of secondary 75 236, as vi wed in Figure 7, is in phase with the,
[7]plate voltage. That is when the grid voltage is positive, the plate vol@age is: also positive-. The positive grid voltage causes a large plate current to flow in the corresponding section of tube 239 which results in a large voltage drop across the corresponding half of primary 243. Since, under the same conditions, the right hand terrninal of secondary 236 is neggtive, the resulting voltage a-,oplied to the grid of the other half of tr@be 239 results in a reduced plate current tl-lerein with a consequent reduced voltage drop across the other balf of primary 243 and the not voltage across said primary is equal to the difference betnveen the voltages applied to the two halves. The voltage drop across the left half of windiiig 243, being greater than that across the right half, terminal 253 is more ne.-ative with respect to ground than terminal 254 and the resulta,nt voltage between terminals 253 and 254 will be in phase opposibion to that across the terminals of secondary 236. Again, consider the efi'ect when the phase of t,he error signal aaplied to primary 232 is reversed frorr. that assun,-ed in the preceding paragraph. In this case, the left terminal of sec- 25 ondary 2.16 and its grid of t,-lbe 239, are negative when the plates of the tube are positive so that a reduced current flows in the corresponding tube section. Since the grid of the right half of tube 239 wil-I now be positive when its plate is 30 positive ' a large plate current will flow in this half of the tube and the voltage drop across the corresponding section of transformer winding 243 will be greater than that across the other or left half. Terminal 234 is now more negative with respect to ground than 253 and the resiilting voltage.between 253 and 254 will be in phase with thst across the terminals of secondary 236. A capacitor 249 of 0.02 mf. is connected across the grid terminals to ttine the c'ircuit to 60 cycles -tO and thereby reduce harr@ionics of 60 cycles in the error signal supplied to the griets which har@nonics would cause one of the tube sections to have a r-,ltich lower gain than the other. Thus a volta.ae appears between ter@minals 253 and 45 254 whenever an error Sig-nal is applied to winding 232 of transformer 231. This voltage has a polarity dedendent upon whetlier contact is made at 2 1 0 or 21 1. While the description h-as been, and will be made wit-'ta respect to the rela- 5( tively large voltage applied to transformer primary 232 LTion closvre of contacts in the synchronizer, it will be understood that the same effects are produced when the field induced in coils 125 rotates relatively to rotor I f'6 and thus r'5 indlices a potential i-p- the primary 232. Any difference is one of degree only. As has been previously stalled, phase 128 of two-phase motor 12.7 is continuously energized frorn winding 229 of transformer 227, over con- 041 di,icto.-s 255 and 256 as will be ol@,,vious from inspection of Figure 7. In order that rotation of motor 127 may be effected and in the proper direction, the phase of the voltage in 129 must be caused to lag or lead the phase of the voltage '05 applied to 128, by 90'. This phase shifting is effected by connect,-,Ons wherein ter.--i-nals 253 and 254 of transformer ivindi-llg 243, are connee't,ed to the control grids of a pair of beam power amplifier tubes 257 and 258 stich as the 7f) 6V6, over conductors 259 aiid 260 havidg resistors 261 and 262 of 2i',IP each, and capacitors 263 and 264 of 0.03 mf. each, Capacitors 265 and 266 of 0.01 ing. each a-re cross-connected between conductors 259 and 260, as shown to provide 5 10 15 20 14 the necessary, 1:)hasa qhift with a MinimUM of attenuation. The, grid bias for tubes 257 and 258 is provided by the IR, drop aeross a resistor 267 having values, of 2500 and 10 watts. A resistor 26,8 of 1 K.. and 2 watts, is connected as shown betvreen: the screen grids- of ttibes 257 and 258, Eind the plate supply voltagefrom a secondary winding@ 269 of transformer 227, and acts to drop t-lie plate voltage to a value suitable for the screen grids. Capacitors 270- and 271' of 0.02 mf. are connected as shown between output transformer 272 and ground to make it resonant at 60 cycles and reduced harmonies in the output. The plate valtage supply for the outplit stage is obtained by a f Lill- wave rectifier tube 273 such as a 5Y3-G Vtth@ condenser-input filter 274 of 3 mf. and conneeted to, 350- valt winding 250 in a manner obviol,,s from inspection of Figure 7. The ce,@iter tap of secondary winding 236 is connected by- conducto-r, 275- to a common terminal of voltage dividers. 276@ and 277 of 50 K. @and 170 K.., respectively, to provide an additional compoiient of A. C. grid bias voltage and aid in effecting wide pul@,es@ of Plate current in tlibe 239 without grid currerit. This A. C. bias swings the grids in the Positive direction with respect to the cathodes during the time that the pl-ates are positixte with respect to the cathodes. Because of the combined effect of the degenerative action of the cat].,-ode resistor 251 and the aforesaid A. C. bias, the Plate curreiit is held fairly constant during the time tllat the plates are positive with respect to the cathode, and plate current is provided in relatively wide pulses so that motor 127 may develop maximum torque for a given average plate@ current. Heater filament current is supplied from winding 278 of tronsformer 227. Regeneration is effected to increase the plate currents in tube 239 by connecting the plate of one section through series,-connected resistors 279 and '280 of 5MO and I.5MO, respectively, to the grid of the other section. Likewise, the iiiate of the second section, is connected through se-riesconnected resistors 281 and 282 of 5Mq and 1.5MO, respectively. A twin diode 283, stich as 6H6 or 6H6G, has its p'Aq-tes eg,@inected to the terrninals of the secondary 248 of tra-,,isfoi.--7iier !Pei In order to prevent hunting, secondary 248 is so wound that the voltages at terminals 253 and 234 are in phase as are those at terminals 254 and 285. Cross connections between the plates of tube 239 and the cathodes of diode 283, are completed through capacitors 286 and 287 of 0.05 mf. each. The Preceding description has been made in connection with azimuth amplifier 43., It will be understood that elevation amplifier 46 is essentially the @same in construction and operation. How-ever,. in the azilnuth amplifier, the gear ratio between motor 127 and shaft 83, is 250:1 while in the elevation.amplifier, the corresponding ratio is abo-ut 1300:1. This difference in ratios makes the azimuth sectiori of the system inore rapid in action than the elevation section and, as a result the time constant of the anti-hunting circuit in the azimuth section must be of less duration than that in the elevation section. To provide tl-i:Ts time differen!@el additioral i@es.-stors 2,18 and 289 of 5MO, are placed in series with resistors 280 and 282, respectively when the amplifier is used for elevation control, and are shorted otil,-, bY contact blades 2 9 0 and 2 9 1, when the amplitier is to be used for azimuth control. The operation of the regenerative circuit will be obvious@ to those skilled in. the art and may be
[8]2,578,666 briefly described as follows. Assume that the error signal voltage at the terminals of secondary 236 is in phase with the plate supply voltage, thot is, that the grid of the left section of triode 239 is being swung more Positive with respect to its cathode. Under this condition, terminal 253 is more negative with respect to ground than if no error signal were being applied to transformer 2 3 1. At this instant the grid of the right hand triode section is being swung more negative with respect to the cathode. The additional negative voltage component from the plate of the left triode section will be added to the error signal through resistors 281, 282 (when used), to the grid of the right section to drive it still more negative with respect to its cathode and further reduce the plate current in said section. The reduction in plate current will reduce the voltage drop betv7eei-i termina, 25A a@.id g,.-ound and cause the terminal to become more positive with respect to ground. As a result, the normal ne@ative component fed from the plate of the right section of tube 239 is further reduced. The grid of the left section is therefore rnade more positive with respect to the ground thereby acting to reinforce the error signal and causing the plate current to increase still further. Thus the voltage drop across primary '243 is much greater than with straight amplification. Because of the symmetry of the circuit, similar regeneration will occur when the phase of the error signal is shifted 1801. Resistance and capacitance in the circuit act to delay regeneration slightly. As an example of how the foregoing regeneration adds to the accuracy and sensitiveness of the sysr,-,m, supp-ose that repeal-ler shaft 83 is displaced from its zeroerror position, that is, alignment of the electrical axis of rotor 126 with the resultant field of coils 125. If simple non-regenerative amplification alone were employed the amplifier could cause the motor 127 to drive the shaft 83 toward zero-error position but the torque developed by the motor would decrease with the resulting decrease in the error signal. Since friction in the mechanical part isunavoidable, the motor would come to a stop when its developed torque becomes equal to the resistance due to friction, thus leaving a considerable error lag of shaft 83 form true no-error position. The regei-ierative feature prevents such errors. If a small error signal persists for a period of time, the regenerative feed-back circuit causes the motor torque to build up relatively slowly, to full or maximum value. 'This function is effected, no matter how small the error signal and the only effect of the amplitude of the error signal is to determine the rate at which the motor torque builds up. That is, any persistent error signal, no matter how small, causes the regenerative feed-back to develop a torque in mbtor 127 tho,t increases as long as any error persists. In all cases, this torque becomes large enough to overcome friction and to drive the shaft 83 tb its true zeroerror position. Under some conditions the voltage built up by regeneration may continue after shaft 83 has reached zero-error position as determined by repeater 124 and thus cause the shaft to overshoot. As soon as the overshooting begins, however, the regenerative circuit receives a voltage of opposite phase which reduces the output of the ampli:fter so that simple amplification of the error signal develops a countertorque. As a result, the shaft 83 is moved to zero-error position, in spite of 16 friction, with not more than one overshoot, and usuallyaperiodically. Operation 5 In operation of the system, the gun and its director, generator unit and any other auxiliaries, are placed in the positions selected by the battery commander and interconnected by multi-conduit cable. The director is adjusted in the conven10 tional manner so that the elevation signals transmitted to the gun are with reference to a horizontal plane. A reference stalce is set at a point easily visible through panoramic sight 70 and the director is adjusted so that its azimuth out15 put signals are with reference to the projectioii upon a horizontal plane, of the line between the pivot center of the gun, that is, the intersection of its train and trunnion axes, and the aforesaid aiming stake or a horizontal line making a known 20 angle with such projection. The telescope mount is longitudinally leveled and crossleveled, and head 79 of telescope 70 is rotated in azimuth until the vertical cross hair in its line of sight intersects the aiming stake. The head may be turned 25 in elevation by its elevation ad,iustment if this is necessary to bring the stake into the field of view. The coarse and fine indicator dials 87 and 88 are adjusted independently of the shaft 83 by a releasable coupling, not shown, to read the 30 same as the corresponding dials of the director and again coupled to the shaft. Knob I 5 I is turned until the indicator 164 is centered. The Icnob is then locked. The director is then electrically coupled to the respective repeaters at the 35 gun, by the closure of appropriate switches. Assuming that the members of the crew are at their stations and that a target to be engaged is sighted or otherwise identified and designated by the battery commander, the director is trained 40 upon the selected target and begins to deliver azimuth output signals which appear at the gun as proportionate rotations of the fields of coarse and fine repeater coils 121 and 125. Assummg that motor 127 is at rest, with only phase 128 en45 ergized, as soon as rotation of the field of coils 125 takes place relatively to rotor 126, a potential is induced in the latter having a phase dependent upon the direction in which the relative rotation has taken place. This potential is applied over 50 conductors 234 and 235 to primary 232 of transformer 231 and, after amplification and phase shift, as explained in connection with the description of the amplifier, acts to energize phase 129 of motor 127, to cause a rotation of the motor 55 127 and shaft 83, in the direction necessary to restore alignment between the electrical a7,@is of rotor (26 and the field of its coils 125. It has been explained that shaft 83 is geared to rotate 36 times for each 360' rotation of the objective 60 79. Since the rotors of transr-qitters 113 and 115 are geared in 1:36 ratio in the director, repeater 120 prevents ambiguity by rotating shaft 123 in step with the rotations of rotor 112 and effecting closure of one or the other of contacts 65 210 or 211 when relative displacement of about 3' occurs between shafts 123 and 200. Thus shaft 83 is rotated in step with rotor 114 without the possibility of ambiguity. At the start of the encounter, the trainer, in 70 seat 58, looks into eyepiece 77 and, by operation of hand wheels 59 and 60, turns the gun and sight as a unit about the vertical or train axis, until the vertical cross wire of his telescope, appears to intersect the aiming point or reference stake. 75 The motor 127, under control of the director azi-
[9]17 muth signals, rotates objective 70 relatively to the gun, equally and oppositely to the rate at which the gun should be moved in azimuth to continuously engage the target and, as the trainer, through operation of his hand wheels maintains the telescope cross hairs upon the target by moving the gun and sight as a unit, the gun is continuously proi)erly aimed in azimuth in accordance with the predicted values of the director. Train rates of .005 to 1.5' per second are possible in the installation selected for illustration. Should the aiming point 29 be destroyed or obscured by smoke or fog, the trai-D-er simply shifts his glance to metor 163 alid continues to operate hand wheels 59 and 60 i-n the manner necessary to keep indicator 164 centered or at null reading. Tv,7o or more ai?ning points may be provided and shift from one to another MaY be made by disconnecti-,,ig counling 84 and rotating head -tC to direct the Iiiie of sight -'o the new point. The coupling is then closed and a4@ming may be resumed in the Us!'-al manner. Simultaneously with the training operation just 2,578,666 18 and pointer o,-casionally -lance at their respective cross-levels and efi-:ect ov-y adjustrnents of cross-levelin.- !,,nobs 7-3 and 296, nece,.zsary to centralize the resuective l@,vels. '-Tt will be understood that convet-itional mea,.-ls a7-e 1,,rovided for adjustir@g or rotating each of the rope-@-ters with respect to itstransmitter at the director alid for securin.- i-t in adjusted position so ti-iat, in all cases,,the re,-eiver dials may be adi4iisted to agree with the corresponding dials of the director. This may be do-,ie, for example, by nlounting each rer@eater so that it may b,- adjus'Lled bodily about its rotor axis and then locked in position. The coars(,, dial 89 is Provided so that the fine iepeater 138 may be ori,,@-,,ited @x7hen the rernainder of t-@le azimuti-i i-eceivc;- servo fails to function. There -is tli-iis provided a gun aiming system that is rapid in action, and Iliglily accurate ond -flox;@ble in operation. -viach Linit n,-lay include 20 f--ror-q o-.ie to four gj@-is and, during in en,@aaew-ent, the rate of fire of each gun is limlited only by the tirle ne-@essary for loading and firing. As a resalb, the concen@tration of acelirate fir-- fi-o@-n eacil battery equipped with the doscribed, predicted elevation. values are received 2i! inve ntion i8 assured. at the elevati-On amplifier 46 from coarse and Wliil e 1 have disclosed a preferred iorm oithe fine ele@,7atio@- transmitters 169 and 165 at the inve iitib,,.i as now known to riqe, nui-.qerous modidirec@uor. Pelative rotation between rotor 173 and ficat fo,@is and subs@@itutions of equivalents will the field of coils 174 energizes the phase 186 of re@ dily oectir to those skilled in the art of gun motor 183 and causes the motor to rotate and 30 fire cohtrol @vitilout alteration of the basic printo drive shaft 179 and quadrant 48. - Synchronicipl es upon which my invention operates. The zation is effected in the manner described in confore going disclosure is r@herefore to be taken in nection with +.he azimuth amplifier so that rno@.o,@@ a-n illustrati@ve, rather -@han a liriaiting sense; and 175 is at ail times in step with transmitter 165 it 4s iny desire and inter-tion to reserve all such and level fol is smoothly and conti.nuously piv- q5 changes, modifications and substi I t u t i o n s a s f a l l w i t h i @ n ' c h e s e o p e o f t h e s u b j o i n e d c l a i m s . -T-laving now ful-ly disclosed the invention, what I claiin and desire to secure by
