US1623320A - Telephone system - Google Patents

Description

April 5 1927. 1,623,326

A. B. SMITH TELEPHONE SYSTEM Original Filed April '7, 1922 9 Sheets- Sheet 1 r Bessay:f 1

April 5, 1927.

B. SMITH TELEPHONE SYSTEM:

Original Filed April 7. 1922 9 Sheets-Sheet 2 llAlL Allll lllll 'I'VV ur Bessay ETITITI'L I A ril 5 192 V 7 A. B. SMITH TELEPHONE sxswsm Original Filed April 7. 1922 9 sheets-Sheet 4.

fiffhur BESSEH SmTfh- A. B. SMITH TELEPHONE SYSTEM Original Filed April 7. 1922. 9 Sheets-Sheet a I F 1 v u 7146i) TZUER DI April 5, 1927. '1',623,320 A. B. SMITH v TELEPHONE SYSTEM Originai Filed April 7. .1922 9 Sheets-Sheet s A- B. SMITH 'rsmrnoum SY STEM Original Filed April 7, 1922 9 Sheets-Sheet 7 --'-ImTmE- 27 A. vB. SMITH,

TELEPHONE "SYST-EM I Original Filed April 7. 1922 e'sneets-snet a Apia 5, 1927.

A. B. SMITH TELEPHONE SYSTEM Original Filed April 7. 1922 9 sheets-sheet 9 fifThur B55553 fa'ffh Patented Apr. 5, 1 927.

UNITE TENT OFFICE.

ARTHUR BESSEY SMITH, F EVANSTON, ILLINOIS, ASSIGNOR, B Y ASSIGN- MENTS, TO AUTOMATIC ELECTRIC INC., OIE CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE.

TELEPHONE SYSTEM. 7

Application filed April 7, 1922,Seria1 No. 550,451. Renewed. Au 'nstiaiesae.

ing part of a Strowger trunking system, which is a system 111 which the oflice names or numbers are related to geographical districts, to be associated with a diiiere nt district withoutchanging its name or number, and consequently topermit a name of number which, according to the Strowger plan would be assignedto an office in one geographical district, to be assigned to an oflice in a different geographical district. The foregoing objects are accomplished by pro viding new and improved trunking arrangements for multi-oflice systems, whereby one or .more routes toward a called-subscriber may be employed tentatively and the proper route definitely chosen subsequently.

Anotherobject is the production of a new device which will be called hereinafter a universal switcher.

Other objects which have to do with the detailed workings ofa complete system will be pointed out and explained fully hereinafter, reference being had to the accompanyfing drawings comprising Figs. l11, in-

clusive, in which Figs. 1-7, inclusive, show by means of the usual circuit diagrams a sulficientamount of the apparatus in a sys tem embodying the principles of the invention to enable the same to be understood; Fig. 8 is a map showing a section of the territory in which the system is located; Fig. '9 is a trunking diagramshowing how calls may be trunked between certain of the ofiices shown in Fig. 8; Fig. 10 is a layout otcertainof the sheets of drawings showing how F igs. 1 7, inclusive, join together; and Fig. 11 shows the front part ofa calling device with which each subscriber s.telephone .in the system isto be equipped.

Of the equipment shownin Figs. 1 -7, in-

clusive, the equipment shown in Figs. 1 and 2 is assumed to .be located in the 6000 branch of Akard, Figs; 8 and 9; the-equipment shown in Figs. 3, 4 and 5, is assumed to be in Akard; the equipment shown in Fig.

6, is assumed to be'in Ghent; and the equip- -ment shown in Fig. 7 is assumed to be in -Ma1n.

The automatic substations A'A?, elusive, Fig. 9, of which the substationsA and A? are shown by means of the usual cir- I cult diagrams, Flgs. 1 and 7, respectively, are substations of the usual automatic type, v

having the usual talking, signalling, and

switch controlling instrumentalities. 'i

The individual line switches associated with thesubstations are of the well-known rotary type in which the wipers have no 5 normalpositionand move in a forward direction only. The circuits of the line switches G and C are shown in full Figs. 1 and 7, respectively," and will be described fully hereinafter.

The universal switcher US, Figs. 1 and 9,

comprises the group of relays shown and 'a" 7 recording device, which device mechanically isa so-called minor swltch. This m nor switch is of'a well-known and simple 0011f struct1on, havmg a single w per which is operated step by step by an operating mag net to pick out aparticular bank contact,

altered slightly so as to prevent the switch ing relay from operating prematurely, 1 grounded before or at the'same' time'thata when the release trunk conductor of these universal bridge is closed across line conductors" thereof, upon the switch being seized. The operation of these switches fully hereinafter.

p The repeaters R-j-R", inclusive, Fig of i which the repeaters R R inclusive, R R ,an'dR l, are shown in Figs. 2,5, and 6, may

be. of any suitable two wire type, and each,

as shown, comprises a repeatingcoil and-a line and a release relay. The circuits of the will be explained repeaters shown in I YigsP-Q, 3, and 6', are" shown in full and will be described h6I]Il'-' after. I i

' selectors E andE; F-F, inclusive, G e-G inclusive; "and H, H H- 1nolulr s1ye,. and I''l$,.-1nclus1ve,-F1g. 9, are 1116- I ch'anica'lly of the well known vertical'and rotary-jtype,and accordingly their bank con .tacts Garey arranged in Thori'zontal rows or levels; The circuitsof all the selectors are,

identical-With eachother'; withthe exception s that those which arepe'rin'anently associatedwith an inter-office trunk do not have release 7 trunk conductors, whereas the local selectors have; The circuitssof the selectors I. :md E,

' which arezra localf and: an incoming selector,

7 respectively. are shown inifull in'Figs Q and and -will be explained fully hereinafter. aThe connectors JJ ',inclusive,\Fig. 9, are

:7 an( l .will be described" fully hereinafter. Ihe', connectors J and J f, it will be under- 7 stood, are each identicalfw-i-th; the connector J,{withctli'e usual exceptionthat, since they are incoming switches; thelr release trunk conductors .are' not carriedback with the i f 'line conductors. Y

whie I 'te'rritory which the present. system Covers,

the entire systemis assumed to comprise approximatelyw200 o'lfices, which are grouped "together in. groups of ten, making in all twenty groups. -Each of these groups forms I 1 x acompletenetwork, there being direct trunks 4O fromeach oiiiceltoevery other office in-the samegroup. 'Only a few. of the trunks however iare shown; the others being 'oinitted' to avoid. complicatingthe drawing. In each N p of tlie main offices of the system, there are as installed first and second. selectors, and trunks to each of the twenty groups of offices are accessible to th e second selectors; )The trunks from any office to any group of ofii'ces terminate in third or oflice selectors at the.

f nearest or one ofithe nearest oflices in that group and froin thence the incoming traffic I merges with; the 'inter oiiice traiiicdocalI-to i iand which'is the switchin center for that Y groupof offices for callscmnmgfrom Akard. A fter-fa connection has been extended from fAkard to Ghent, thenext turnofthe 'calling theigrou'p. prior example, in Fig. 8, the group "o'fitrunks froni Al'rard to the group-ofoflices in '-whicl1"' Ghent is located terininatey as shown", at Ghent, which; is the nearest} office,

1 deyice' causes a third cor-10mm selector in c to o'pe'ratel and "piclirout' the desired= ofiic'ein' tlie"usualiinanner; Q I Itf'mayfbef stated at this time'that accord 'ing tocommon practice for systems of this Referring {now particularly to Fig. as' beforestatemjshows a part of the 7' size, the'lettersof the alphabet appear on the cal-ling device (Fig. 11) and the oflices are listed in the directory before the subscribers? numbers; for example, MAIn l926. Vlhen a subscriber calls this number, Main is reached by dialing the first threev letters l\i[-,Al-I, or the letters that are capitalized; I p

and the subscribersnumber which comprises foi'ir'digits is called after the ofiice has been selected. The various oflices in the group in which Ghent is located are' reached throu gh one common group oftrunks by inultipling,

together the correct levels of the second selectors, gas will? be hereinafter explained;

The one condition, however. is that the third letter in the otiice name 'cannot'be the same for any two ofiices in the same group" nor can it be in the samehole in the calling device, which amounts to practically the same thing. Vi hen such a'conflictarises; the two conflicting" offices occupy the same level in the third selector'ban'lmnnd a separategroup oftrunlts is required; @The names offt'lie offices in the district for which Ghent is th'e switching center have been chosen-so that the third letter" does not come in the same hole of'tlie' calling device," showir in' Fig. 1'1,

for any'two of 'them. Inor derto show more clearly which ofi'ice names are numerically similaig'the numerical equivalent of. the first three letters of each o'fliceis written in 'pa V rentheses;

- It will lee-noted that there are only seven oiii'ces shown inthe group 'in whi'ch Ghent is located. There are three other office names Mia-clay, TopaZ,'and-Maliope, however, which, according totheirfir'st three l-etteii's'woiil'd ordinarily not have been assigned: or if assigne dy would have been assign-ed to oiiic'es in the Ghentdistrict. It is assumed that these names belonged tothe oiii'ces towhich they are ass gned while the system was n ia-nifialiy operated andtliat the subscribers would v not readily consent w a change of the oiiice names'whfenthe system was changed to autoa iiiatic-o Ie'r'ation: That being t hecase; these three'o 'ce names remain unchanged;- which means that ,Macey, M aliope, and Topaz, are a remotely'situatedpart; of the groupof offices. V in which: Ghent-is located, 'Th iscondition makes it necessary; when calling Main, to 1' take a ti'unk to TopaZ a't the sain-etiine a trunk is selected" to Ghenhbecause the first two letters, M-+A, oft lain are the first tivo. letters ffil a-hope. When the next digit is dial-ed one of the two inter-oiiicetrunks is V freed, and' the calli'is completed over nit t r.- v Southern or Topaz is callcdgithe first letters thereof appearing in the sa-me'hole on the 1 calling deyice,'Fig; 11*, and thesecond letter Obeing co nmonto the twoi'- When ia'cey' is being" called from Akard,

the'callingpf thefirstf-two letters, M'-A-, re 130 sults in a'trun-kto Topaz beingseized'and' The 'sani e thing occurs when either also atrunk to Ghent. It is assumed, however, that Macey, Which is much nearer Akard than Topaz is, is near enough, and that the trafficto it from Akard is heavy enough, to warrant a, separate group of trunks to it from Akard. Consequently, upon the calling ofthe next'letter C, the trunk to Ghent and also the trunk to Topaz isfreed and a direct trunk is taken from Akard'to Macey.

Another situation wherein the universal switcher is used to an advantage arises in connection with the completion 01' local calls inthe 6000 branch of'Akard, and in com 7 Akard desires to call the subscriber at sub plet'ing calls from the 6000 branch ofAkard to the 9700 branch of Akard. 11', when a call originates in the 6000 branch of Akard,

the letters A, K and A of Akard are dialed and the first digit is 6, a universal switcher in the calling branch ofiic e operates to restore the trunk to Akard to common use and the callv is completed through local switches. Similarly ifthe first three letters A, Icand A of Akard are called and the lirsttwo digits are 9 and 7, thetrunk to Akard is freed and a direct trunk to the nearby 9700 branch is connected up and the call is completed thereover.

It will beunderstoodthat other and simi lar problems are connected with each of the other: districts in the system and that there may or may not be branch 'oflices associated with each-oflice, and that the examples given are chosen merely as beingt ypical ones.

Referring now particularly to Fig. 9,

.whichis .a trunking diagram showing how station Atin Main, therotary line's'witch C operates to pick out afirst selector, the selector E forexaniple, upon the removal of; the receiver at the substation A, and

when the calling device is turned inv accord-- ance with the firstletter M, which letter appears in the fifth hole of the calling de-, vice, Fig. 11, the: said first selector E raises its wipers to the fifthlevel and selects an idle trunk, the trunk extending to the selector F for example.

When the calling subscriber operates his calling device in accordance with the'second letter A of the oflice name, which letter appears in the first hole of the, calling device,

the second selector F 3 raises its wipers to the first level and selects-an idle universal switcher, the universal switcher US for example. When this occurs, the universal .switcherUS connects up the rotary secondary switches D and D whereupon they operate to select trunks to Topaz and to Ghent, respectively, the trunks extending by way of the repeaters R and R for example. Upon the calling device beingturned in accordance with the third letter I, the oflice selector G" in Topaz and theoflice selector G? in Ghent raise their wipers to the first level and proceed to search for idle trunks.-

The first level of the selector Gin Topaz is dead, and accordingly its trunk selecting operation. is of no avail at this time. The first level of the selector G in. Ghent is connected with rotary secondary switches which have access to trunks to Main and, assuming that the rotary secondary switch D is the one selected, the rotary switch D operates to select an idle trunk to Main, the

trunk extending by way of the repeater R? and teri'nmatmg 1n the selector 1-1 for example. Y Y

1n the universal switcher US a di it recording device (not shown in this drawing) disconnects the rotary secondary switch D, thereby freeing the trunk to Topaz. In response to the calling of the digits in the desired, number, the selectors H and I and the connector J operate in the usual manner to extend the connection-to the substation Assuming now that the subscriber at sub station A desires to converse with a subscriber whose lin-eterminates in the Topaz ofli'ce, the line switch C. operates in the usual. manner tofind" an idle first selector,

the selector E for example, when the re?"- ceiver is removedatthe calling substation, and when the calling device is turned in accordance with the first letter T, which letter appears in the seventh hole of the calling device, shown in Fig. 11, the selector E raises its wipers to the seventh level and picks out an idle second selector, the selector 7 4 F 4 for example. When the calling device is Iturnedlin accordance with the second letter O," the se lector F raises itswipers to the tenth level V and plcks out an idle'univ'ersal switcher, the universal switcher US for example. lVhen this occurs the rotary secondary switches, D and D are connected up, whereupon they seize trunks to Topazand to. Ghent,"

respectively, which trunks it will be assumed are the ones shown in the drawing.

When the'calling device'is turned in accordance with the thirdletter P, the selector G and G raise their wipers to=the sixth level and rotate them in .search'ofidle trunks. The trunk selecting operation '01:

the selector G in this' case is of'no avail,

oflice' raises itsv wipers the siicth level being: dead. The selector G,

' fll'OWBVEIglDl'CkSOutfain' idle selector the select'or H- tor'I'eX-ample,

l n th'e universal switcher US the digit 'frcordirig device, uponoperating in accordancew-itlr the-third digit of the number,- dis- 7 'connectsthe rotary switch;-D whereupon V the-trunk to- Ghent is freed.

The call-ing subscriber now operates his callihgdevice in accordance with the remaininglpart of the number, whereupon the usual selectors andconnectors are. operatedto eX tendlthe connection to -the desired line in the usual manner;

'aniple calling. a subscriber in Southern in-V st'ea'd 03f Topaz, would have stepped up 'i t-reedathe trunki'to trunk to;Gl1ent.-

picks: out an idle second selector the Se;

ffso.

-the first level;

selector, theJselector H for V V at substation A in the 25. V office, he removes switch whio "0 k rd; which is.

i-Ijt' wil l 'be'und'erstood that it the calling subscriber had been, in the preceding ex? the. switches G and {G toth'e eighth level and the universal switcher US wouldha-ve Topaz instead of the Assuminginow. that the callingsubscriber 6000 branch 0t Akard desires to call some subscriber the [universal switcher US for example: .Whcn secondary switch-D versal switcher Us operates to pick out. an idle trunk 'to Akard=, .the trunle'extending' by oh the repeater It. for example, there y being: no first; selectors inthebranch ofiice.

' The rotary switches D and D however, are.

not connected. 1113- for the. time being.

When the callingdevice is turned in accordance withthe first letter A, which letterappears inthe first hole in the calling device, the first selector E. in the Aikard to the first level" and lector-F for example;

response to the calling: of the second hole' of the calling device,

selector; G for example, the calling. of: the third example. 7 i

If the-nextdigit called isi any digit 'eX-;

.ceptlti' theselector H, upon operatingin re- 7 7 sponse too-f the digit;- seizesa local fifth. se-

lector. :I-Iowever,izt' the neXt digit; is 6,,the selector: raises itswipers to the sixth. level and picks out an ldlB, rotary secondary to the 6000 branch hasaccess the branch in which the "call originated, the rotary secondary switch D ?or X I P r. theun'iversal switcher'Us' n i l W hen this occurs,howevcr,

branch. otfice,-,- havingrecorded. the digits 7 calls the: digit 9 after t e y and A, the connection is extended to a local fifth selector, the selector I'flforthe usual manner.

in the A -kard his receiver, whereupon the" 1' 'rotary'line switch picks-outidle unii ver s'ali switcher,

thisoccurs, the rotary associated with the uni:

dialed, disconnects the rotary switch D and connects up the rotary secondaryswitch whereupon the trunkto Akard" is freed; the switches in Aka-rd are released; and the trunk from Akard back to the originating" branch ofiice is freed. secondary switch D? In r sponse. to the n being conn t d umafi V idle selectoris seized, the selector 1'1 for 7 example. l he' calling subscriber now' the three remaining digitstof the numberin the usual manner, whereuponthe call-is completed locally withouttieing up any inter-ofiice trunks.

calls 7 "Assuming now, that the, 'call'ing'subscriberI having dialed the let ters A, K

example." It the next "digit 'called' is any digit other than'Z, a local conn'ector'is seized r 7 and thecalling of the remaining digits eX'- tends the connection to the desired line in- Hot'vever, i-fthe digit is 7, thewipers are raised to the'seventhlevel, and an outgoing rotary secondary-switch, the switch D for example, isiseizedl That being the case, the switch. D seizes a trul'ik' thus tar dialed, disconnectsflthe trunlt to Akard, whereupon. the" connecti-on; established to Akar'd is"released; The

to the 9700 branch of Akard', which s a" branch oflice containing only '1 00.l'ines.

lVhen' this occurs, however, the 'unive'lsa'l switcher- US, having recorded all the digits switcher US also connects up the r'otary' secondary switch D; whereupon a; direct trunkifr'o n' the 6000 branch to the 9700 branch isseized and the connection is completed thereover in response to the calling. of the we remain-- 'ingjdigit's in the desiredj number;

having" been described ,7

The apparatus, more-or less in general',' will now bedescribed in connection with a detailed [description, of its operation. pose, it willbe assumed that the subscriber at substjation A, Figs. 1' and 9;,desires to :converse"with theisubscriber" at substation For this: pun- A Figs. .7 and 9, and whose number is VVhenitlie receiver 1s-removedhttlie s' b. f

station A, acircuit is completed over line;

conductors 2 and 3, tor line relayG, of the line switch C. Upon energizing; line relay 61 places ground-upon private normalcom ductor 4 atarm'ature 12', thereby making the calling line busy innnediatelyin' the banks of the connectors which have access: toit; The placing ot ground upon private normal coiiductore also closes a: circuit forswitcli- 1.

relay 5", and stepping magnet'lO, in i As a; further result of the energiz s: I tion of line relay 6, it connects: the test wiper series.

14 to a point in thecir'cuit between stepping magnet 10, and switching relay 5, at arm-a3 ture 11. From thispoint' the op'erat'ion d'eipends upon whether ornot the trunk, upon switching relay is short circuited, and

stepping magnet 10, which interrupts its own circuit, operates in the manner of a buzzer to advance its wipers step by step in search of an idle trunk. Then an idle trunkis reached, which trunk it will be as sumed is the one terminating in bank contacts 1618, inclusive, switching relay 5,

being no longer short circuited, energizes in series with rotary magnet 10. Rotary magnet 10, however, does not energize at this time, on account of the high resistance or switching relay 5. As a result of the ener'-- gization of switchingrelay 5, armature 8 opens the test circuit and prepares the holding circuit, thereby placing ground upon test contact 17, which makes the seized trunk busy immediately. As a further result of the energization of switching relay 5, it'disconnects the line conductors 2 and 3 from ground and from the winding of line relay 6, respectively, at armatures 7 and 9, and extends them by Way of the working contactsof these armatures, wipers 13 and 15, bank contacts 16 and 18, and armatures 4E5 and 47 to the upper and lower windings of line relay 26 of the universal switcher US.

QUpon energizing over the calling subs-cribers loop, line relay 26 closes a circuit for release relay 27 at'armature 49. Release relay 27, upon energizing, prepares a locking circuit for relays 3033, inclusive, at armature prepares a circuit for operating Jnagnet 90 at armature 51 and at armature v 52 places ground upon release trunk conductor 20, thereby establishing the usual holcL ing circuit for the line switch C, by way of bank contact 17, wiper 14, and armature 8 and its working contact, before the-slow acting line relay 6 has'had time to deenergize. Asa further result of the energization of line relay 26, it closes a circuit for impulse relay 36 at armature 48. Impulse relay 36, upon energizing, closes a bridge across conductors 1.08 and 110, whereupon line relay 171 of the secondary switch D, upon energizing, places ground upon release trunk conductor 109 at armature 179; connects switching relay 170 in series with stepping magnet 172 at armature 178; and at armature 177 connects test wiper 181 to the above circuit at a point between switching relay 170 and stepping magnet 172. The switch now operates in the same manner as explained hereinbefore for the rotary line switch C to advance to wipers ISO- 182, inelusive, into engagement with an idle trunk, and assuming the trunkcomprismg conduc-' tors 183185, inclusive, to be the first one energizing, opens the test circuit'and 'pre pares the-holding circuit at armature 17 5;

places a shunt around armature 178 and working contact at armature 174; and-at armatures173 and 176'dis0onnects themcoming trunk conductors 108 and 110 from line relay 171 and from ground, respectively,'and extends them by way of wipers 180 and 182, trunk conductors 183 and 185, and the left hand windings of the repeating coil of the repeater R, to the upper and lower windings of line relay 186 of the repeater R. Line relay 7186, upon energizing,"closes a circuit for release relay 187 at armature 188, and release relay 187, upon energizing, places ground upon release trunk conductor 18 1, thereby" establishing the usual holding circuit for switching relay 170 of the switch D. As a'further result of the energization of line relay 186 of the repeater R,'it closes a bridge across the conductors 191 and 192 at armature 189, whereupon line relay 210 of the distant selector E'in' Akard energizes, thereby closing a circuit for release relay 2 11. at armature 220. Release relay 211, upon energizing, prepares a circuittlor switching relay 214 at armature 221,and at armature 222 opens a pointIin the circuit of release magnet 215and-prepares'af circuit for vertical magnet 219. v

The calling subscriber now operates his calling device in accordance W-ltll the first letter M of the desired office, thereby producing five interruptions in the circuitof line relay 26 of the universal switcher US,

Fig. 1. Each time line relay 26deenergizes in response to one of these interruptions, it opens the circuit of impulse relay 36 at armature 48, and each time impulse relay 36 deencrgizes, it opens the circuit of line relay 186 of the repeater R, and each time line relay 186 of the repeater R deenergizes,

it opens the circuit of line relay 210 of the selector E. Each time line relay 210 deenergizes in response to one of the five interruptions produced in itscircuit, it closes the following circuit for vertical magnet 219: From ground by way of theresting contact of armature 228 and said armature,

a locking circuit for itself at armature 224:,

and at armature 225 prepares a circuit for rotary Inagnet 217; Upon the termination "of the vertical niovernent, slow acting ree 5'l1-y ;21,2 itdeenergizes, thereby completing {the circuit of notary magnet 2 17. Rotary Qmgagnet 217,1upon energizing, advances the r w pers 230 232,,:inclusive, into engagement ;.withe the tirst,set'oif'bank contacts atthe same Ftirne eo'pe'ning the circuitlof stepping relay :213 at interrupter contacts 233. Stepping :nelaay, 2313, upon deenergizing, 7 opens the .cir-

:cnit 10f r-rotaryniagnet 217;, at armature 225,

' 1- and r tary. mag e 2. 1119011 e f i e fleloses-tts interrupter contactsg233 again.

Ere; this point, ith e' operation depends pjon Whether or; not the trunk terminating -in ethe iirst set of contacts is busy. If it is idle, switching relay ,Qltenengizes immeately and, if it is busy',switchingrelay 21 ishort sircuited by the ground potential which is present on .the'test contact thereof,

' stepping relay 213 energizes again,

, #whereltpon rotarymagnet 217 energizes also,

thereby 'advancingthe Wipers into engage- I Janent with-the second set of bank contacts.

21, ha il is alternate,operationlof stepping relay and rotary magnet". 2L7 continues ;a;n'1idle-tr-unk is reached. l/Nhen an flgielle trn nk ii s reached, which trunk it will opens the test cir- 'a;r;mature 220 ofline relay 210 at armature -nects the incoming trunk conductors 1-91 and 192 from the windingsof line relay 210 and c' en endsith m byway f W p 23 9133, th9' fhi\];1l contacts with Which these wlpers are rengagenient and theassociated trunk conductors to the upper andlower windings "Fort theline relay (not shown) ofthe selector F When thisnceurs, the selector F is preresponseto theienergization. of-its-line repa r-ed tor operation the usual manner in 111 9 J {Inthe universal switches US, line relay f2 6 upon deenergizing in response to each oi the interruptions produced in its circuit the calling device at the callingsubstation, in i addition to opening the circuit of inngpu-lse relay 36 at armature 48', closes the ,following circuit for stepping magnet 90:

from ground byway of the restingcontact jot armature 46 and sald armature, armature f49and'its resting contactfarmature .51 and e 1 V itsavorkingcontact, relay 28, and stepping ,magnet 90 to battery. By the operationot the steppingmagnet 90,-Wljll0h receives five impulses over ,thislcircult, w per 99 1s ad- Named-"step bystep u-ntil it .cornes to rest upon the fifth zassociated bank contact .95.

:11e1ay28 1s energized 'in' series with stepping magnet and, being-slow actlng, retains relay 2 5,

its armature attracted throughout the series of impulses. At the end of the series off-impulses, slow acting relay ,28 :deenergi zes,

thereby closing .at-armature 53 a circuit for release magnet 91,by. Way 0'1 ofi" normal eon tacts 93. It Will 'benoted tha't \a'branch of this circuit extendsby Wayof armature '92 of release magnet 91 and its resting contact, lower Winding of relay 29, and wiper 99, to

bank contact 95. Relay 29, however, ,does not energize at this time forthe reason that bank contact 95 is not connected up so aslto I 7 complete the circuit. Release magnet 91, upon'energmmg in response to the clos ngof its circuit, closes the following circuit for seizing relay 35 From ground by way o'f the restingzcontact of armature 53 a11d said armature, off normal contacts 9.3., armature 92 and its Working contact, nesting contact-of armature 55 .and said armature, and the up- .per'windingof relay 35 gto battery. Asy'a further result of the ,energization of release magnet 91, it restores the Wiper 99 :to normal, its own circuit, and the circuit of the upper inding of relay 35., being opened at .ofi normal contacts 93 when, the W'lP-6rI99 reaches normal position. As a result of the momentary closing of the circuit of the upper win-dnig, Winch Winding is of low resistance and efficientandconsequently has-a vstrong pull, armature ,7 6, which is adjusted 1 to operate easily and to operate before the other armatureshaye moved, is brought into V engagement Wlth its Working ontact, them- Q r D to release trunk conductor 20." jRe-lay 35," upon renerglzlng fully, extends release'trunk conductor 20 through to releasetlflunk conby locking the associated loWerayinding ,ductor 109, of the secondary switch D" at] armature 7.7 extends tlietrn'nk conductors 1 9 and 21, to trunk conductors "1,08 c at arlnatures' (MC-and 78; and at armature T5 closes a circuit for cut ofi' relay 25,. f Cutofii' upon energizing, 7 ground from armature 4-9 of line relay 26 at armature 4E6, and at armature 45 and 47 disconnects trunk conductors 19 and 21irorn'the windings of line relay 26. Line relay "26, upon deenergizing, opens the circuit of in1- pulse relay 36 at armature 458, and impulse 1 V relay 36, upon deenergizing, removes the lodisconnects;

cal bridge from across conductors 108 and 110 atarlnature 7 9, therebyleaving line relay 186 of the repeater Rf underjthe direct control of the calling device atsubstation A. 4

Release relay 2:7, upon-(leenergizing in response to the ground being removed from 'armaturel -9 of linerelay 26 at armature 46' of relay 25, disconnects'ground from release trunk conductor 20 at arlnature 52,leaving the saidconductor grounded by Way of the holdingcircuit which extends back from armature 1'90 .ofrelease relay 187: of the irepeat-er R. p I

The first letter in the desired number havuse ' ing been dialed, the net result so far accomsince thatletter determined definitely that the'call is not intended for a subscriber that may be reached by way of one of the alternate paths, has definitely seized the trunk to Akard and has disconnected its own line relay and consequently will not respond to the calling of the remaining part of the number.

" Then the calling subscriber operates his callin device in accordance with the second letter A of the desired-office, a single interruption is produced in the circuit of line relay 186, of the repeater R, which interrup- "tion is relayed bythe line. relay of the re peater R to the line relay (not shown) of the selector F Fig. 3. The selector F now raises its wipers to the first level, rotates them, and picks out an idle trunk, which trunk it will be assumed is the one extend- P to the seizure of the switcher by the selector E closes at armature255 a circuit for rering to the universal switcher US. That be ing the case, line relay 244 of the universal switcher US, upon energizing in response lease relay 2 15. Release relay 245, upon energizing, prepares a circuit for stepping magnet 247 at armature 257, and at armature 250 places ground upon release trunk conductor 2 11, thereby establishing the usual holding circuit for the switching relay (not shown) of the selector F and the switching relay 214 of the selector E. As a further result of the energization of the relay line I 24 1, it closes at armature 254 a circuit for impulse relays 266 and 269 in multiple. Re-

I lay 266, upon energizing, closes a local bridge across the conductors 285 and 287 of the rotary secondary switch D whereupon line relay 302 energizes and the switch proceeds-to select an idle trunk in the hereinbefore described inanner. Assuming that the trunk extending to the repeater-R and comprising conductors 303-305, inclusive, to be the one selected, switching relay 301, upon energiz ing at the end of the trunk selecting operation','extends trunk ,cOnduct01's'285 and 287 to the line relay ofthe repeater R and prepares the holding circuit. Line relay 315 of the repeater R upon energizing inresponse 'tothe seizure of the said repeater, closes av circuit for release relay316 at armature 317. Relay 316, uponenergizing, places ground upon release trunk conductor 304 at armature 319, thereby'establishing the usual holding circuit for switching relay 301 of the switch D As a further result of the energization of line relay 315 of the repeater R it closes a. bridge across the conductors 325 and 326 at armature 318. lVhen this occurs,

- the line and release relays (not shown) of the selector G in Ghent, energize, thereby preparing the switch usual manner.

In the universal relay 269,-upon energizing in multiple with conductors 291 and 293 at armature 284, whereupon thesecondary switch D selects .an idle trunk in the usual manner, which trunk it will be assumed is the one extending to the repeater R -That being the-case, the line and release relays of the repeater for operation in the I switcher US, impulse V impulse relay 266, closes a local bridge across? R energize, thereby closing abridge acrossthe associated out-going trunk conductors and establishing the usualholding circuit for the switching relay of the secondary switch D. In response to the closing of the bridge across the conductors of the trunk] outgoing from the repeater R*, the line land release relays of the associated incomingselector G in Topaz, Fig. 9, energize, thereby preparing the switch for operation in the usual manner.

When the calling subscriber turns his railing devicein accordance with the third letter i m the name or the (lQSIIGd OfllCB, one

interruption is produced in the circuit o': t line relay 186 in the repeater R, and the said line relay 186, upon decnergizing in response to this interruption, produces an interrup tion in the circuit of line relay 2% of the universal switcher US. Line relay 2%,

upon deenergizing, opens the circuit of impulse relays 266 and 269 at armature 254,;

whereupon these relays deenergize also, thereby momentarily open ng the associated bridges at armatures'283 and 284;, In re sponse to the opening of the bridge across conductors 285 and 287, line relay 3150f the repeater R deenergizes momentarily,thereby producing an interruption in the circuit or the line relay oi the selector G in Ghent. \Vhen this occurs, tlle'seleotor G raises its wipers to the first level and rotates them in search of an idle trunk. Assuming the trunk extending to the secondary switch D to be the one selected by the selector G the said switch D operates inthe. usual manner to select an idle trunk, which trunk it will be assumed is the one extendingto the repeater It. That being the case, the line andrelease relays of the repeater R? energize, the former closing a bridge across the conductors of the associated inter-oiiicetrunk, which extends to Main, and. the latter establishing the.

the switch for operation in the usual manner.

By identical operation, the momentary .deenergizat-ion of impulse relay 269v of the universal switcher US, Fig. 3, produces a i the: 1 associated selector gamer Blow-acting relay momentaryinterruption in the "circuit f the il-in' relayio repeater iii-which relay iii-turn repeats the interruption to the hinelrelay of y 7 Gr :in llopaz, Fig. 9. sflvhen thisocours, the selector-G. raises its wipers-to the first level and rotates them in searchpof an id le itrunkf- It will be noted, -howeveraithat the :lirst level of the. selector is -deadand,' consequently, ithe trumk selecting operation of the said selector G OGS HOLPGDfOIHi-MIY useful at'unction'at this f tii m'fl" y i in the universal -switcherUS.,-line relay *%l4,' -upon deenergizing in response :to the f previously mentioned momentary interruption pied-need in itscircuit, not only opens *i the circuit of'inipulse relays 266 and 269,

7 asiexplained but also closes .the iollowing circuit for stepping magnet 2&7: vFrom ground by" way or resting contact of varmature 253 and --Sflltl ZH'H1&EL1IG,- armature "and its resting contact, armature its Working contact, relay magnet-247 130 -ba'ttery. By the operation "single im'pulse'atthis time, wiper 249 :ad-

' Val-16851; into engagement with the first bank 2&6 is en 'ergized in series "with stepping magnet 24? E I -and retains-itsarmature attracted While the ewi per isheing advanced; Uponthe termination of theinipu lse, slow acting relay 246 *deenergizes, thereby closing at armature 258 the circuit of release nagnet 24.8, by way of nor-mal contacts 250', avhich contacts heca neclosed'-.when Wiper QEQE'HIOVGd 10111. ;'-Re=lease inagnet 24 8,

its; normal 1 positii ni.

-which Elias aconapa ratively heavy armature and also 'a stifiyspning adjustment, ,is not 94 able; to energize immediately and hesitates sn iil l traction of a second. It will he noted' that a loranch of the-circuit of release Qf :--1n'agnet 248-extends hy ay-of armature 262 its resting con- 1-of releaseinagnet Q48 and associated ba-nk tact; wiper 249, the first contact 9/59,;and seizing relay 265 toloa 'tery; Release/magnet 248,11pon energizing,

of an idle trunk. Assuming that the :tnunk reaches normalposition. Tl-l9 tiine that Q ela'pses, het-Ween'the closing o f the circuit of L "release'rnagnet248;:and the circuitof relayand at armatures at garinat-ure 271'. Gut ofi relay 24B, upon eneng zing, removes ;grounc l- {of stepping magnet 247,: Which receives a" switcher US, upon deenerigizing in response I restoresitto norinal, its circuit being opened a Lo'fi' normailfcontacts 250- \vlien Wr1'3e1'249' 4 in the .desired'nuniher, the selectoril raises response to 213l1eSBiZUre10tfl7l1e switch by the selector I3, and closes .a circuit roi release of-thesecondary switch D at armature 234e,. 270 and 273 extends trunlr conductors 24c and 242 i130 the itriink iconductors 1285 and 28? of the-switch gD -As a further :result of the energizationof seizing relay 26:3,it closes a circuit for cutoff relay from arn1atu=re255 of l nelrelay at armature V 253, thereby opening the CllCL11t of release relay 245, and pat armatures 251 and disconnects line relay 24A from .line con .7 duotors 240 and 2&2. Line relay 24%.,a1 p0n dee'nergizing, opens the cireuitoii iinpnlse relays 266 and 269 at armature 25 i. -.Lnipu lse relay 266, upon deenergizing,j removes. the local :bridge .ironi across trunk conductors 2-8.5 and 287 at iar-inature28ii, thereby leavv ng the line relay 315 of the repeater R under the direct control of line relay 186 of the repeater R", Fig.2. Impulse relay :269 of the universal switcher US, upon dcenergizing in response to the deenergization 257 and 2&6, "and stepping of line relay 24A, removes the local -bridge from across conductors .291 and 29.3 at .arinatnr'e 28.4,, whereupon the-connection ito Topaz is released .and'the repeater R and asso- :ciated trunk reverts to common nse'inzthe usual manner. j

Release relay 24:5,

I of the universal to the energiz-ation :oi-cut-o'fi' relay 24:3,.re:

'inoves ground from Release .tru-nk conductor 24H at armature 25E), aleavlnjgth-e'said con-V ductor grounded by way of the holdingcircult which extends back from armature 219 of release .zrelay .316 of the repeater R Fig. 5. 1 1 r w The.callin 'lsuhscriber non turns his call ing device in accordance with the fir-stdigit' IQO 9 in the desired nuinher, whereupon. nine inyCBII'UPtlOllS are producedi-n the-circuit of the line relay of the repeater R :and are iI'Q- ilayed to therepeater-B and f-roln thence t0 the incoming selector H, Fig. i7, :byiway of the repeater R", Fig. .6. In response to the nine interruptions proctncedin :the circuit of its line relay, the selector H raises its wipers to the ninth level, and rotates them in search its wipers to :the fourth thein in searchof an idle connector.

suini ngt-he connector J to be the first one l oundao she idle, line'relay 561 energizes in relay 503 at armature 514.. Release zrelay v503, aipon ienergizing opens :a point-in the circuit of the release magnet 510 and prepares a cinouit for vertical magnet 50.9 at

armature 517, places ground upon armature 522 of busy relay 506 at armature516; and at armature 515 places ground upon release trunk conductor/198, thereby establishing the usual holding circuit for the selectors H and 1?.

Thev calling subscriber now operates his. calhng device in accordance with the next I the following circuit: From ground byway of armature 514Iand its resting contact, armature 517 and its working contact, resting contact of oftnormal spring 513 and said spring, relay 504, and vertical magnet 509 to battery. By theoperation of vertical n'iagnet 509, which receives nine impulses of current at this time, the shaft and wipers oi the connector J va-re raised step by step until the latter come to rest opposite the ninth,

level of ,bank contacts, which level is the one in whichthe line of substation A terminates. Relay is energized inseries with vertical magnet 509, and being slow acting retains its armature attracted throughout the vertical movement, thereby maintaining 1ts own circult and that of vertical magnet 509, at armature 518, intact after the oil normal springs have shifted, as they do upon the first vertical step. At the end ofthe vertical movement, SlOW fflCting relay 505 deenergizes, and transfers the impulse circuit from vertical magnet 509, to rotary magnet 511. V

The calling subscriber now operates 111s calling device in accordance with thedigit six, which is the next and last digit in the desired number, whereupon six interruptions are produced in the circuit of line relay 501. Each time line relay 501 deenergizesin response to one of these interruptions, it closes a circuitfor rotary magnet 511 as follows: Fromground by way of armature 514 and its resting contact, armature 517 and its working contact, normally open contacts controlled by ofl' normal spring 513, armature .518 and its resting contact, resting contactv of armature 523 and said armature, armature 530 and its resting contact, and rotary magnet 511 to battery. By the operation of rotary magnet 511, the switch wipers 532-4335, inclusive, arevrotat-ed step by step until they 'come in engagement with bank contacts 535-537, inclusive. Relay 507 is energized in multiple with rotary magnet 511 and, being slow acting, retains its armat-ure attracted throughout the rotary movement. Upon energizing, relay 507 disconnects test wiper 533 from switching relay 508 and connects it, with busy relay 506, and

t m u e 6, pl a sheet arQenia ture 5 23 and tsresting contact, so as to maintain 1ts own circuit and that of rotary magnet 511 intact, in case busy relay506 energizes while test wiper 533 is passing over busy contacts. i I

Assuming first that the line of substation A? is busy, in which case there is a ground potential upon test contact'536, busy relay 506 is energized at the, end of the rotary movement and slow acting relay 507, upon deenergizing, completes the following lock ing circuit for busy relay 506: From ground by way of armature 516 and its working contact, armature 522 and its working; contact,

normally closed contacts controlled by arm'a ture 525, and busy relay 506 to battery; In, 'ca-se, armature 523 of busy relay 506 having been operated, as a-turther-rd sult of the deenergization of slow acting're lay 507, it disconnects itself androtary magnet 511'from the impulse circuit at "annature 5 26, The switching relay 506 cannon energize, even though the callingline should become idle, and busy relay 506, being locked througha local circuit, cannot deenergize as long as release relay 503 is energized. As a further result of the energization of busy relay 506, it connects at armature 524 a lead from the right hand winding of the transformer associated with the'busy machine T c with the loweritalking conductor, therebv sending back a busy tone to the calling sul'i scriber, which tone informs him that .he cannot obtain the desired connection for 'the time being. The 'subscriber, upon hearing this busy tone, replaces his receiver, where upon the connection is released in the usual manner. v V f Assuming now that the line o't substation A is idle; when the wipers of theconnector J arrive upon the bank contacts 535 537, inclusive, in which case there is no ground potential upon test contact 536 andbusy re lay 506 is not energized, slow acting relay 507, upon deenergizing upon the cessation of the operating impulses,closes at armature 525 the following circuit for switching relay 508 and switching relay 538, of the connector J andthe line switchC respectively, in series: From ground'byway of armature 516 and its working contact, armature 5 22 and its resting contact, upper winding of switching relay 508, resting contact of arrnature 525 and said armature, test wip er 533, bank contact 536, switching relay 538, and steppingmagnet 539 to battery. Switching relays 538 and 508- ene rgize in series over this circuit. Stepping magnet539, however, does not energize on account of the high re-- sistance of relay 538. Relay 588, upon en'e'r'- gizing, clears the called line of its normal battery and ground connections, but owingto aninterlocking device (not shown) be tween its armature, and that of. line relay ""5' lfthe' arin'ature of el'ziy 538 operates only about half way and consequently the ass eia'ted wipers arenotconnected' tip.

' In the nneemr J, re ay "'08, ii'p'on:'ei1erthe lightlyadjnsted armature 529; which arihatiire is steel so e to operate first;

disconnects rotary magnet 51'1 a I-idi ele'y 507 iii-emf the 'i'n pnlse circnitfet arinatiire so that any further operation of the calling device will he ieeeeeeve iniepermngeater magnetsl'l; places threc t' gi oiiiid on test 7 1 M533 at armat tile 528 ii n'd'ab a riiit biif s 521 and 531 connects up the line'i'vrpers' '532 and 584', whereupon ringingeurremnem the interrupted generator leadfis pit-ejected but oyei the celled line returning Way *cifthe testhe called stil efit'ly fin the iisnal {lVhen the'called subscriber i'espoii'jds to the ring'ing' of hisfbeltl removing his receive-i,

a direct eurrent bridge is placed -"a criess conductors of his line; Where'upon n u-t ore1ay-505 in the co energizes winding it the "lightly 'aclj' ust ed --ar1n'a'tiire 520, which armature is' i djnsted to" Se he fore arniatu-ies 51 9 and 521 br'eailtawey their esting eontects. Upon hilly energizcalled line-t0 the upper andlower windings V 'ofthe battery "feed impedance 502;

'The calling zindc'alled subscribers inaynow c onveise with each other in the visual man 1 5 neg-the t alkingcircui't 'beiiig oiit nec'l ley the "heavy" conductors. Talking battery is sup plied to transmitter ,of the Calling substa- .tion from the line -relay of the repeater HQ.

Fig-. 2, andato the transmitter of the called I 'siibstat'ion from battery feed impedance 502 of the conneotorJ 7.

' After the conversation is completed, the

two subscribers heplae'e their receivers. WVhenf'th'e receiVeris replaced at s-ulostation A, the circuit of'line relay 18'6- Of the re- .peater R" is opened, a ndthe said relay up} on dee'nergi'zing; opens the circiiitfo'f release relay 18 7 atlerinature 188, end at armature 189 opens the circuit or line relay 315 at gizing, opensthecireiiit ol' the associated re Returning nowto 7 elease relay l8 7,-upori deener'glz-mgre ov lease relay at'its ep erermaeer and its lower armature pens thefciietiit of line re lay 501; of the connector '5 Line relay 501, ,u en deei ergizing opens the cire'n it of ie-i leeserel'ay 508.

the repeater B, Fig; 2,

position;

from release trunk 'condlictb'r F184, whereupon switching relay 17001 the sec o'ndaiy switeh D, seizing relay 3'5 of-flhe universal 'switehe'r US, out 03 relay of the saine switcher, iiiid switching relay 5 of the line switch C deenergize. This restores c'ondi one in the line switch C- to nori'nal renders the *universal switcher US, the secondary switch D, and the repeater B ao- V ce'ss'ible for commo mse.

1n the repeatei E, Fig. 5; release relay 5'16 iipon'dee'fi'ergiizing', removes ground froni et'iiiii'k'concltiotor304 M armatu re319, wee nioonre'lay 301 of the secondaryswiteh D "seizing relay 265ahd cut oil i'elay 243 I of the universal switcher US, the switching and the rel-1y (notsl'iowii) bf the selector F sit: relay 214 et the selector E deenei'giz y Y the secondary switch D and the uniyersal s itcher U-S'aie r stored to normal. In the selectors Eand 1*, the respective release me -nets ene'l' giz'eend restore thep'switdhes to I Whenthis *oceii'rs, conditions in normal, the'c'iiciiit of release magnet 215 of tlieselectoi' E being as follows From ground by Way of the resting contact of armature of switehing relay 214 .ancl said armature, a'rinat-ure 220 "and its resting Contact, annatfuie' 222 and its resting eontact 'ofinorn'iel contacts 216, and release 1nagnet215 to batter-y. When release ma net 1-215 energizes,

the shaft and wipers of the switch, are re stoi edto normal position in the usual nian- 116?, the circuit vof'rele'ase magnet 215 bep opened {it normal contacts 216 by thefsw it'ch shaft whent'he latter .iieaches norlln response tothe deene'igization of the release relay of the repeater li 6, the

ground petential is removed from associated release trunk conductor, whereupon l the switching relay of the switch D and the switchingreley'(not shown) of the selector G deenergi'ze; VV'hen' this occurs, the wipers ofthe selector G are fest-ored to normal position the-usual manner. 1 In the connector J, release relay 50?), upon deenergizing in response to the opening of its circuit by the deenergization of. the line relt-y '501, removes ground from armature 522 'et'arniatur'e 5'16 removes groundfrom release trunk conductor 4:98 at armature 415, whereupon. switching relay 508, ring cn-t "of? relay 5-05. a-hdthe switching relays (not-shown) of the selectors H9, andl deene rigi'z'e'. In'response to the deenergization oit switching relay 503, the biisy potential is removed from the test cont-act ofthe called line set armature 528, and in response to the '(leen ergizfation of the switching relays of the selectors H and I the two selectors are restored to normal position loy the operathe connector J, the following circuit is closed for release magnet 510: from ground by way of armature 514 and its resting contact, armature 517 and its resting contact,

voft normal contacts 512, and'release magnet and. A coincide with the first two letters of Main, but which, due to reasons hereinbefore given, is not reached through the same switching center as Main. That being the-case, the calling subscriber at'substation A, after having removed his receiver, dialsthe first two letters M and A with the previously described results, which are that a universal switcher in Akard, the universal switcher US for example, is seized. It will be assumed that the universal switcher US is seized at this time, as before, by way of the universal switcher US, secondary switch D, repeater R, and the selectors E and F It will be assumed further that the secondary switchD associated with the universal switcher US seizes the repeaterR with the consequent result that the selector G in Ghent, Fig. 6, is prepared for operation in the usual manner. It will be assumed still further that: the secondary switch D associated with the universal switcher US, seizes the repeaterRfl which results in the incoming selector associated therewith in Topaz being prepared for ru 'eration in the usual manner. 1

- W hen the calling subscriber operates his calling device. in. accordance with the next and third letterH in the name of the desired office, four interruptions are produced in the circuit of line relay 244 of the universal switcher US by the operation of'the line relay 186 of the repeater R, which line relay is controlled by the calling device at the calling substation, and upon each of the four momentary 'deenergizations, line relay 244 opens the circuit of impulse relays 266 and 269. Relay 266 in turn, upon deenergizing, interrupts the circuit of line relay 216 of the repeater R which in turn interrupts the circuit of the line relay (not shown) of the'selector G As a result, the wipers of the selector G are raised to the fourth level, and are then rotated in search of an idle trunk. Upon referring to Fig.

9, it will be noted that the fourth level of the selector G is dead, and consequently its trunk selecting operation is of no'utility at this time. i

Impulse I relay 269 of the universal switcher US, upondeenergizing in response to each of the interruptions produced in its circuit by line relay 244, interrupts the circuit of the line relay of the repeater-{R which line relay in turn interrupts the circuit of the line relay of the associated selec tor G, l ig. 9, in Topaz. As a result, the selector G raises its wipers to the fourth level, aid rotates them in search off an idle trunk. Assuming that the trunkextending to the secondary switch D is the first 'one found to be idle, the said switch D upon being seized, selects an idle"repeaterg' 'which.

repeater, it will be-assumed, is the'ropeater R That being the ca'se,'the incoming selector H in Mahope,is in the usual manner. I

In the universalswitcher-US, as a further result of each deenergization of line rela-y 244, it closes the usual circuit for stepping magnet 247,and as a res'ultfwiper249 is advanced into engagement with the fourth bankcontact 261. Series relay 246,upon

deenergizing at the end'of the series of 'impulses delivered to the stepping magnet, closes the usual circuit for release magnet 248. /Viper 249, being upon contact 261, extends the circuit to seizing relay 268. Seizing relay 268, upon energizing, closes prepared for operation the usual'locking circuit for itself at armature 280. Release magnet 248, upon energizeing, disconnects wiper249 at armature 262 and'restores it tonormal position in the usual manner, its circuitbei'ng opened at off normal contacts 250 when wiper-{249' reaches normal position. As a further re:

sult of the energization of seizing relay 268, it connects release trunk conductor 241 with release trunk conductor 292 of the switch D atarmature 281; closes a circuit for cut off relay 243 at armature 279; and at armatures 278 and'282 "connects: line conductors 240 andx242 with line conductors 291 and 293 of the switch'D"-. Cutoff relay 243,"

lay 266, upon deenergiz ing, opens the bridge across conductors 285and 287 at armature 283, whereupon the connection to Ghent is released in the usual manner. Impulse relay 269, upon -deenerg1z1n'g, opens the local bridge across conductors 291 and- 293 at Iarmatures 284, thereby leaving the control of the line relay of the repeater R with line'- relay 186' of the repeater R. Releaselrelay' 245, upon deenerglzlng, disconnects ground from i release trunk conduc'tor'241 at arma-

Images