US1603267A - Telephone system - Google Patents

Description

Oct. 19 1926.

' 1,603,267 4 H. B. BROWN TELEPHONE SYSTEM 10 Sheets- Sheet 1 Filed June 13, 1924 Mi an/0r."

Oct. 19,1926. 4 1,603,267"

H. B. BROWN TELEPHONE SYSTEM Filed June 13, .1924 10 Sheets-Sheet 2 Oct. 19, 1926. 1,603,267

H.B. BROWN i TELEPHONE SYSTEM Filed June 13. 9 10 SheetS-Sheefi 4 fie ry 53 Brown.

Oct. 19, 1926;

H. B. BROWN TELEPHONE SYSTEM File d Jun 13, 1924 Oct- 19 1926. 1,603,267

' H. B. BROWN TELEPHONE SYSTEM Filed June 13, 1924 10 Sheets-Sheet 6 Oct. 19,1926; 1,603,267

H. B BROWN TELEPHONE SYSTEM I Filed June 13, 1924 10 sheets-sheet '2 V y r Affy.

Oct- 19 1926. 1,603,267

- B; BROWN TELEPHONE. SYSTEM Filed June 13, 1924 10 Sheets-Shet' a Wye/#0}.- Henry 5. Brown. i

3w a? 4 r v 6K e Qv v 9? n. in l.I-\l all. m Nmnmm Emm mu lnnlw P w R .2 sfi Hi1 PM R Q \1 3st;

Oct. 19, 1926.

1,603,267 H. B. BROWN TELEPHONE SYSTEM.

Filed June 13. 1924 10 Sheets-Sheet 9 AffK/ "Oct. 19 1926 1,603,267 H. B. BROWN TELEPHONE SYSTEM .Filed June 13, 1924 l0 Sheets-Sheet 10 I /m/e/7/0/ flew/y E Brawn.

Patented a. '19,?1926.

- INCORPORATED, oFnEw YORK, .N. lY.,-=A' oonroim'r on or I NEW YORK.

Application i d June 13, se a it 719,750?

This inventionrelates' to telephone systems, and more particularly, to' a system wherein connections are established by means 1 of automatic switching apparatus.

of ten keys nuinbered from 0 to 9.

in accordance with this invention each operator in a manual telephone ofiice s, provided with a group-of ten keysone 'forieach any distant office "T he digits thus of the digits 0 to '9, and a group of oifice keys one forv each office to which she has access. To reach anyjjfline in proper 'oflice key and then proceeds to write up in succession upon the ten; keys,

the digits comprising the nun lo'erfl of 1 the, called line. writen up are recorded by a register sender. Depressing the ofiicekey',

causes one of a group of circuits','cal'ledlink the operator.

; digits comprising circuits, to simultaneouslyhunt for and seize the calling operators po sition,'a'n idle: trunk to the desired'oflice, and fanidle register sender. V j" When an idle trunk s fo'und,the number of the seized trunk is visibly indicated. to 1 The registers in the sender:

are set succession in accordance with .the

.line, and fter the second digit has 'been recorded in the register "sender and an idle trunk circuit has beenfound, the first digit is transmitted over the trunk circuit in the form of mpulses and? one of a train of switches at the distant mechanical. foifice is set. When thethi'rd digit has been recorded the second digit is transmittedgover ,fthe

trunk circuit, and so on. WYhen the last digit is recorded,Ythe' plug of a cord isiinserted T in the jackof the trunk circuit, and

the digit; last'recordediis then transmitted over the trunkcircuit. "The' calledline', if

idle, is seized, and

spending" conversation' takes place -in "the. 'VVhen the last digit is is signaled, and uponreordinary' manner. 7

recorded, the position equipment is dis cherged, and when tli'e last1d' g1t 1s trans fmitted, the reg ster sender iSQalso disc'harged to,,,whi ch she has'f'access' the operator .,-1nerely" depresses c the Fig. 2 represents the number of the called j when the fc'over'sauon tmtie ta disconnect. signals {are given "to [the operator,

and disconnection takes place intheordinary way.

.A vfeature of invention airin s.

ment whereby the operator may at will'call any line, consisting of'any n-urnberof digits, asdesiredp v Q I.

iernother feature of this, invention is the arrangement.whereby thedigits are recorded :and the proper selectionsini' accordance therewith take place 'si1nultaneously one diginhowever, always being held in reserve have been recorded.

drawings comprising ten sheets nu nhered Figsfl to 11 which are placdasindicated, r .in Fig. 11, the invention is schematically set- I,

forth.

until the operatorindicates thatall digits;

Fig. 1 .represents a callingsubscribers -h'nej1nfa manual; oflice andaa typicalcord Qther features-will appear [from thjde tailed description] whichyfoll ows' z In" the 1 5 circuit commonly'used in establishing a conand any. called-line.

nection between thecallin' 'lline' as indicated allottin g an idle link circuit such as is disclosed inIFigs-A and 5;

shown, which' isused in 'routinga connec- 'tion'to a trunkifinderswitch "such asthe'one shown in the center; of Fig. 8, or at the right oiIFig LZQ J' m, Fig. i 5 :2; 'pe'siedn gfincii i switch ands sender jselectoi'fswitohi are'a'lso shown. The Q 7 trunk: finder switch ,i(l ig. '3jor 45), position 9 .iinderlswitch (Figs) and sender selector switch (Fig. 5);.areallQcontrolled 'by' the the 'allottercircuit At .the left, Grie a steering sweet is linkcircuit (Figs; 4128161 15,) so thatas-soon as a call is initiated, the link circuit functions causingqthe jtrunk "finder-switch, position finder switch andSender selector switch tdr'opsatesimultaneously to findfrespec: 1-1

Fig. 7 'the fposition. indicatingf'equipin'ent, which fis iisedit'o indicate to the op;-

erator' the number lot the trunk? seized-f Zby tively, the first idle truiik, oalliiig posi the trunk finder -I't "she mi-t understood i the? es 91 s efli e ey simi ar-M1 key;

610, for each distant mechanical ofiice to which the operator has access.

In the upper right-hand corner of Fig. 3f

and in 'Fig. "'8 are shown two trunk circuits, such as" are used in establishing a connection to the distant mechanical oflice (F1g4 8);

Fi'gs.-i9- and IO-show the register senderequipmenhficonsisting "eta group of registers which are set in Various combinations under control of the numerical keys (Figl fii to operate the counting relays (Fig loiwhich count off the number ofimpulsestransmitted over thetrunk circuit to the distant mechanical 'ofiice for setting the automatic switches therea t. Aninterrupter "shown at theupper right hand corner of Fig; 9 is used for producing the impulses. required. The sender also provided, as indicated at T.

'S. with a "timing switch fo'rlmeasurin'g off a definitetime interval between each trainrof impulses transmitted to the distant 'oiiice', to permit "the switch at the distantoiiice to-have sutlicient time to trunk hunt before another series of impulses is transmittec ly'a "recording switch which advances one step "for each digit recorded by the operator to transfer the register leads from one group of registers to 'the next succeeding group; and a sending switch which is operated by t he interrupter to control the 'transmi'ssiono'fimpulses to' thetdistant me- Answering call.

WVhen the receiver is removed from the switch-hook at the substation #1, (Fig. 1) the line relay- 2 operates over an obvious circuit including the substation loop, and the line ilanrp=3 isulighlted. The plug of the cord-6 is inserted in the jacl' 5 opera'tingthe cut-oil relay 4, thereby opening the circuit through the line relay 2 which releases eX- assume'to be. the substation tinguishing the line ilainp '3. The supervlisory' relay 18 is operated thereby preventing supervisorylamp 17 from lighting. Listeninglrey 8 is operated, connecting the operatorsa telephone set to the calling substation l. The 'cailfling substation-J1 givesthe number of the 'clesiretl :line which we 'wil l a distant -central office :of a full mechanitcal-step-by-step system.

N p 7 I Operatifl'lz'nlc circuit. V I The key 610 i 6'), which is designated by a code corresponding to the centraloflice icsja easans er? to ground, The

depressed by't-he operator, closing .a' circu t to operate relays 613 and-619 as 'follows: battery, armature 633 of relay 618,j63 t,urightl winding of relay 619, 635, left-winding of relay 613, 636, 637 co-ground. Relays619 and 613 operatedv lock by way 'oi' H V 7 7 operation of the ofiice key 610, also closes an obvious circuit to operate relay 612. When the otiice key 610 is released, relay 611 operates in series with the winding of relay'612 and relays 61-1 and" 612 =lock'in s eriesto ground at armature 669 of relay 619. j

There is a group of link circuits for each trunk "route to 'which the' eperaitor :has access, and an idle-link circui t is always preselected by the selector switch of the allotter circuitso that thebrushes 230 to 235 inclusive oftlie selector switch in Fig. 2 are nor- :mally resting uponthe terminals. of an idle link circuit, whichwe will assume tobe the link circuit shown in;Figs. 5. Under these circumstances the operati'onpt relay 613 will'close acircuit to'opera'te relay2D0 (Fig. 2) as follows: battery, armature 638 I of 'rela'yfile, 639, 625, "501,-2%,"resistance 201 in parallel with the winding ofre lay' 200 resistance 202 in series, "to ground. Relay 200 operated operates "relay 205 'as follows: battery, 206, 207,208, winding or relay 205, 209, 210to ground. Relay 205 operated locks by way 'o f' its armature 239 to ground and (i'pe'rates relay 24-6 over an'oh VlOUS CIICHlt,

associated with the bridge '236 fthereby' 'preventing relay 288 from operating thus rendering brid'ge236 ineffective, until "the first ela 24r6opera'tedopens 210 the ground to the winding of relay 238V bridge 250 I we performed its function, after relay 246're1eases,

'iVhenf the interrupter 251 is closed relay 247 operates over the'following circuit r battery, armatureaee of rela 2 11, winding-cf interrupter. 251 247 operated connects relay 247,249, 259, ground. tRelay ground byway creams the winding of re 251 is opened, relay alarm signal unless relay {211 hasoperated in the meantime .as;hereii1aft2r described.

' Relay'508 operated lo clrslby way oitih,

5 86 and 589 to ground,v-and closes acirc'uit to operate relay 509 as follows:Qbattery,

511,512, 513 to L to operate relay 11-7 as winding of Irelay 5019, 510, ground; and a circuit follows: battery, left winding =of relay 1 1?,

5116, 5915, 510., 511. 512, 513, to ground; The function ofirelay 117 will be hereinafteiideoperatecl-locks;as follows: battery, winding of relay 509, 59.61

scribed. Relay 5 09 52 4 0; a p a-t e 513 to'ground. Relay 509'foperateii con way of 203, 500,

- overthe following circuit: batter-y,

C: Cl

to'that shown in Fig;

i i ,7 to operate nect s battery to the networkconsisting of resistances201 and202 and 'the winding of relay 200 asfollowszbattery, armature 519 of relay 588, 518, 517, "516, 515, 514, ,500, V

' this manner, an idle link circuit if available is always preselected by the allotter circuit,

203, 202 to ground.

it Will be recalled that a circuit was closed when relay 6l3;operate'd byway of. 625- and 20410 operate relay 200. When relay 509 operates as previously. described,

thecircuit including the resistance 202v by etc, balances the circuit including the resistance 201 by Way of 1, 501, 625, etcJa'ndthus the potential at 255 1 and 256- is substantially the same; hence re-v lay'200 releases, opening at 206 the circuit through-relay 205 which also releases.

operate relayv 523, asfollows; battery winding'ofre1ay523, 524, 525, 526, 527, 4100,

;.401,402,403. -101,-52s,529,.,512, 513 to ground. Relay 523 operated locks by; way of "537,"512 and 513 to ground.

The stepping magnet 227 now operates windingof theqstepping magnet 227, 226, 217,

218, 219, 228, 229. brush 230, 210,520, 521,

' :522 to ground: :Relay 2l1. operates in paral lel withsthe stepping magnet227, and opens u= at 248- the circuit through relays 247 and 258 which release.-

. takeplace; ing properly before interrupter251 is again 'These operations all only incase the call is progressclosed so'thatr'elay'252 willnot ordinarily h'ave a'chance to operate and by i0pBIat1ng relay 261 start the trouble .;alarm 253.

V .Presleoting a nfic lle The stepping magnet 227 operated, opens at 226 its own operating circuit, thus releasing and stepping the brushes 230 to ,235

, inclusive'one step in an anti-clockwise dilink circuit similar to which the brushes 230; to 235" inclusive are "now connected is busy,*the relay; corresponding, to relay" 523 rection. If the nextwill be operated 'and'ground will be conits lead corresponding to lead 240 to:th'e 'brush" 230 "andxthe' circuit the stepping magnetf227 will agairi be closed causing itto' operate and; V again release {and rotate the 235 inclusive nected 'by way ofanother step. This cycleaof operations continues until the next idlelink circuit is' such Jlink circuit corresponding to. jrelay' 523 found; in which case 1 the relay in will n ot be operated, hence groundiwillnot itslead. corresponding to be"; connected to 11 M210,- and the circuit to operate the; step "ping; magnet 227 "being open; the magnet will.riotf re'operate, "and relay 211 will, re- "lease. As long jasthe stepping magnet 227 is" operating and releasing,

freinoving 1 ground 55212 from: brushes; or 231f2LS'tl1Q case may be-prevents the re;

. Relay 509 operated also closes a circuit to of relay to be very 589 to ground.

releasing,

,Iclockwise direction.

positon finder. jswitch1 brushes 230 to to relays 508' or 598 from perating until an idlel ink circuit allotter circuit Fig. 2 is again/normal. In

408 "as follows: battery, winding of relay408, 476, 521, 522, to ground, The function of relay 4:08Whichis designed 7 slow to operate, ishereinafte'r more fully described. Relay 53.8 operated closes'a has been found and the,

v to groundfltelayalsocloses a circ'uitto start the operation lays i'n-the preselected' li'nk corresponding 'right-windingof relay.538,54c7,'548, 519, a559, .brush 540, 59.6, .513

circuitfto' operate. relay, 539 as \follow's':

battery, left winding of relay 5 39, 569', 579,

ltelay 539 operated locks as follows: battery, right winding of relay 539, 5010, 521,522 to groundI,,A lcirc'uit is now closedtooperate'the stepping mag. net 536 of the position findergflswltch. as "follows: battery, windingof the stepping magnet 536. 558, 568,578, 569,- 579,"58 9 to ground.

The stepping. magnet 536 operated opens at 5155'its own operating circuit thereby: 7

5 15 inclusive to rotateron'estep in an anti- The function offlthe ping magnet 536 is attempting to Relay 613 of every. operators position and causing the brushes 540 to i K with which the stepe 1 associated isito" theparticular'position whose operator is establish. a. connection with the step-by-step central oflice shown 1111 except the position we are seeking will be normal hence, groundzwill be connected to every terminal in the are 530 except the terminalto which lead 502 is, connected whicl'i 1 willibe econnected by way off626, .657, left winding of: relay 614:, and 633' to battery, I

The relay 538, will remainlocked. over bridgsing brush 5 10 to groun-clontheyariousten -min'a ls'i the arc ntilbrush5l10 comes to rest upon the terminal to which lead 5021s connected when relay 538 releases, open-; 'ingiat 579thecircuithofthe stepper mag i net 536. whose brushes 540m .545 inclusiye now remain .atfrest upon the terminals as 1 sociated with the:.operatorsl,position sliown. i

in Fig.6-

I Relay 538"released closes a icir.-- @1111; to operate relays A105 andv 614- .as fol 1 lows battery, armature 633 of relay 618, left ,windin'gofrelay 61 4, 657, 649,626,502, 5410,

5'56," 406 winding operate relay 538 as follows: battery, flet'tz i Cit .tors position to test busy to all other-positionfinder switcheswhich may be hunting at this time or at any time while this call is progressing.

' Relay 405 operated closes a'circuit to operate relay 58.8 as follows: battery, winding of relay 558, 599, 409, 418, 419, 402, 403,- 404,

528, 529, "512, to ground. ,Relay 614 operated locks through its right winding byway of 648 and 647 to ground and opens at .638 the battery supplied by way'ot 625 and 204 to t'heresistance 201 of the bridge network'(Fig '2). The operation of relay 614 opens at 648 the holding circuit through the left winding of relay 613 but the latter relay remains looked over. the following circuit: battery armature 63.3 of relay 618, 634, left winding of relay 619, right winding of relay 613, e57, 649, 626, 502, 540, 559, 540, 548, 547, 55 7, 556, 406, winding of relay 405, 407, 567, 577., 587 to ground. Relay 588 operated, opens at 519 the batterysupplied by way of 500 and 203, to the resistance 202 o'f the bridge network (Fig. 2), and closes the following circuit to operate relay 575: battery, '519, winding of relay 575, 525, 526, 52 7, 400,401, 402, s, 404, 528, 529, 512, 513, toground. The function of relay 575 will be described in detail under selecting an idle sender. Battery is removed-from leads 625 and 204 under control of relay 614 slightly in advance of the removal of 'batteryfrom leads 500 and 203' by the operation ofrelay 588.]. This precaution is taken to prevent the unbalancing of the bridge .in'etwork from momentarily reoperating re- *1a 20.0. I It Should bejobserved that only the posi- .tion finder switch associated with the step ping magnet 536 is used at this time. There are five postion finder switches of .which three are omitted from the drawing (Fig. 5) only the first and last switches being shown.

I Since each switch has a capacity of twenty 7 group of 20 operators will only function =5). when an operator in that group is seeking 1 operatorsthe total capacity of all. five switches'is operatorsythe last position finder switch. being associated with the last to establish a call "tothe otlice shown in 8 In case the operator initiating the call is in the .last group, the lead corresponding to v625 associated with the last bridge network (it should be observed-that there is atotal of 5 leads similar to' the lead 625, one tor each. group 01620 operatorslwi ll unbalance thelas't bridge'netwoik 236 in which case relay 237' will operate in turn operating relay'238. Relay 238 operated will close a circuit tooperate relay 598 as follows: "battery, winding of relay 598, 241, 231, 254,260,213,

212, to ground. Relay*598 operated, will. function in general in the. same Inanneras relay tog-whose functions have already been nest. 5.44,4114.15444455 44; A circu t jsertsthe plug 10 ofthe-cord-circuit (:Fig.

in the trunk jack 807- ("filsas finder switch associated with the stepping magnet 536.

Tmmk sition finder switch was huntingfor thezpartic-niar calling position, the sender selector and trunk finder-switches were respectively himting for an idle sender and an idle outtrunk in the mamier hereinatter ide .It should be observed that whi:le.:the:po-

outgoing trunk similar to necting ground by wa of 808, and-43.1.t0

the associated terminal of the are. 411, .or; the relay corresponding to relay 438 will beeperated to connect" ground to the brush corresponding to brush .421. In either. case if brush is resting uponthe ltenniinal. eta busy trunk there will be ground 10.11 the corresponding terminal of the M0411. An (JP- crating circuit for the stepping magnet426 is now closed as tollowszbattery, winding of stepping magnet 426, 427, .428, 328, 307,

420, 434, 435, 436,322,- are, 346,317.,

437 421 to ground on.thehuntinmterminal i ("J b of the trunk upon whichthe :brush 4216s new resting. The ground on .this lulntir gv terminal short-circuits. irelay 3438] whose winding is also connected tog-ground at contact 439 of 'relay'417 thus preventing relay 438 trom operating atthis. time. ",Thestepping magnet 426 in operating opens at .427 3 its own'o'perating circuit and releases, thus steppingitsfbrushes 410 to 4-15 inclusive {onestep to the terminals of the. next trunkin the group. This cyclewo f operations conti nues until an idle trunk. is found at; which time the hunting lead corresponding to lead 431. will be free from ground. W/Vhen an idle trunk, which we will assume to be the one shownin. Fig. 81's toun(l,ithe groundwvhich previously short-circuited relay 4438 ;is removed permitting this-relay to toperatevin series with. the stepping magnet 426, but the stepping magnet 426 will not reoperatefldue to the'high resistancerof the winding-of .re.-

lay 438 in series with it. ltelay-438operated' conn cts ground .at 435 byyway otg436, 322,

312, 316,317, 437, 421, to 431,'c1a.using=the t'runk selected to test busy. to all other. trunk finders in the group. .It 5 is necessary j to i connect this g'roundto the. lead 431 to cause the trunk to test busy because the busy ;.ground on the lead 809 under control of relay ,806 will not be supplied until'th'e operator iner lainpsbeing lighted toindicate the trunk from 0 to 159. Each first group and ground.

to ground. 1

- atz'ag the trunk Y After the trunk and the positionhaveibeen found it .is necessaryto designate tothe jop': erator the number of fthej trunkfselected. This is accomplished by meansof' agroupoi number. 7 I, I 1

It has been determined that160'j trunks between oiiices is a reasonable number to allow under the worst traflic cond tions be -tiveen busy 0tfices,hence this circuit is ar-" ranged to indicate the number of any trunk trunk finderswit'ch 1s exceeding '20 trunks,

traffic conditions. eight trunk selector switches would be required in order'to. obtain a maximum of 160 trunks. For the purpose ofillustration only two trunk finders having a maximum of trunks havebeen shown, but the explanation which follows applies to any number of groups comprisingfrorn'l to 160 trunks as required, the only difference beingin the amount ofequiprnent used.

'Assuming that the trunk picked is in the is trunk No. 10 asjshown' by the position of the trunk leads in Fig. 4

' of the drawing, it will be necessary to indicate' to the operator that trunk No. "10 has been selected. to 315 of the steering switch w1ll be resting .upoi 1 the fourthterminal of their respective arcs, in which position the, first trunk finder switch is used. 'lheoperation of *relayJ474 connects leads 7 22 and 721 of the trunk number indicator (Fig. 7) by way'of leads 622 and'621, 545 01 the position finder switch, leads 590 4114591, 490 and491, 492 and 493, 494 and 495, 324 and 325 to'brushes 314 and'315 of the steering switch. In this casebrush314 resting. on. the fourth terminal of the steerencounters an open. clrcuit c'onmg switch dition andlead622 remains open. Acircuit is closed, however, over lead 621 as follows: ground throughthe left winding (high resistance.) of relay 480, brush 315, 325, 495,

4.010, 491, '591, brush 545, 507, 21, 721,

'. 7 32, right winding of relay 709, right wind 725, 720, 620, 630,- 631, w

ing of. relay 713, I battery. Relays480 (Fig. 4) 709 .(F1g'. 7) operate but relay 713 being marginal does not operate due to the highresistance of the winding of relay-480 in series with it.

,Ptelay 709. operated, looks through. its left winding by way of 745, 724, 624, and'647 to Nith relay 709 operated, acircuit is closed to operate relay 704 whichis designed to be slow to operate and which operrelay' 7 Relay 703 In this-case the brushes 310 I ates relay leads 506 and 507, brushes 544 and ates and, closes an obviouscircuit to operate is'likewise designed to I -Belay"703,- operated, transfers the leads 722 and 721 to the wind be slow. to operate."

ings of relays 710 and7'14, and of 7 11 'respec-' tively.1fRelays 703 .andl704are niade slow tooperate sothatwhen relay '709 -operates 721'a11d722, the t'ransferjofthe register closinglthe operating circuits forrelays703 and 704 in succession -to 'transfer the" leads relays; will bedelayeduntil after relays 480 and 481 in the link circuit (Fig. 4) are lay 482 'whi'chwilloperat later to transfer the leads'492 and 493' 4) to the next .iiully operated" preparing the "circuit for re succeeding resistance network of the register control combination." Bytransferring the register leads 721 and 722 firstfno dif v p p .ficultyis experienced because each transfer arranged to hunt over a'trunk group of not hence under the worst;

in the; register circuit (Fig. 7 changes the circuit'condition from battery to ground or. from ground to .batteryfas the case maybe,

or ground jto a ground circuit as the'case may he, the'succeeding group of register relays {(Fig. 7 isnot Tafiected. It is'only' when the transfer is completed in the link circuit 4) that thefnext succeedinggroup 'of register relaysare capable of being operated. The operation 0r-re1 y4s0 in ithelink circuit closes an obvious circuit to operate relay 481'. which locks undercontrol of relay474. Vfhen' relay 703 finallypper- 480 releases, closing'a circuit to ne'registercircuit. before completing operate relay. 482 thus transferring leads 1492, and 93 in the linkcircuit (Fig.4) to brushes424. and 425' of the ,trunk '[inder switch, .Briishes 424and425 have taken the same setting as the bru'shes 410 to 418 inelusive, which in "this case will be the eleventh corresponds totrunk'10! terminal {or their.v respective are which 7 The. eleventh terminalof arc" 4141 4154 connected to the resistance IlJGtWOIlQflIBIlCE ilead remains open, preventing; either relay 710 orrelay 714 from operating. But a circuit is closed over'1ead621 to operate relays711 and 483 as follows: ground, winding of relay 711, 732, 721, 621, 507,; brush 545, 591, 491,

p v right-windingof relay 483 (high resistance), 484,485, 486, 487 .580, 581 to battery. Relay 711 operates and locks "and closes an obvious circuit to operate slow operate relay 707, which N in' turn operates slow operate relay 706. Relay 706 operated,

operates the slow, operate relay 705, thus 7 498,441, brush 425, eleventh i terminalof' arc vv415,

transferring leads 721, and722to the-leads 726 and 727' leading to the, relays 715, 716,

' 7 "to ground,

the 713i 13313 706, 3114707. are

designed 'to be slowto operate to permit relay 483 to operate before leads 721v and 722 are again transferred;

oiiereftiiig 3116331313 3. 11313 713 and 717 15 3434 switch'the main batteryfeed forliglitihgjt 1e tens lamps from the even to the odd lamps. The, zero hundreds l31hp700 willnew he lighted from battery at 765, 15111112700, 734 to ground. The tens lainp"(728 will now be light-ed from battie by, at 7111314113 728, 743, 744, 734 to ground. Tl 1eu'iiits 13111 729 will. now be lighted trofri'battei'y a t 778, 13111 729, 750,751, 734, Hence the lamps displayed will read 010 indicating tIlllllI number 10.

Assuiniiig that at the time of trunk ellth e triinks'connected to thearc of trunk finder switch (Fig.- 4) are busy, thenthe stepping niag'iiet 426 will continue to operate 3nd rotete the brushes 420 to 425 inclusive step-by-step until they sire resting upon the terininsl twenty-first 111 each of the 31 3 419 13 iiiolusive. At this time brush 421 will be resting uiion the teriiiiiizil 449 of the are 411 Mid as this terminal will 7 be connected toground the circuit to opertte the stepping magnet 426 (previously traced): Willbe. againv closed aiid the stepping m aghet 426 will reopera'te. The stepping magnet 426 will be prevented from re- 7 leasing; by the, closure ofthe following hold- III.

in}; circuit: battery, winding otthe steppj g' magnet 426, 443', 329, 311,. 321, 447,424,

446, 4:45 ground. A circuit is now closed operate the st pping i iag'net 306 of the steei ing switch F ig. as follows: battery, wihdihg ofthe stepping hiagnet 306, 308, 3,20,. 3 10, 327, 444, 443, 477, brush 425, 497, 440 to ground. Thestepping magnet 306 opens at 30 8 its own operating circuit and r'el eeises, thereby rotating the brushes 310 to 315 inclusive onestep in an anti-clockwise direction. When the brush 311 advances, the holding circuit for thesteppi'ng magnet 426 is opened, releasing the stepping mag- 114342'3 and rotatihgthe brushes 410 to 415 inclusiveof thetrunk finder switch one step in. an aiithclocliwise direction. In this po- 4) ,will be repeated.

siti'on' all" the b15111she's1 except brush 1 32 out i of Contact with any terminals" of their respective arcs; The are 411 has one ter niinal' more than the other arcs of the switch. Consequently, in this position, the brush 421 is resting upon the terminal 440 and is, therefore connected to gr'oundet that point. The brushes 410'to 415 incl t sive' will remain in this position and the trunk finder switch (F ig. 4) will not again beuseduntil all of thetrun'ks in all 01 the other' groups to the same distent 01-11 4 have beenhunted over, h V

1 The trunk fiiider switch associatedwith the stepping magnet 306 (Fig. has access to otl1ei-"groups' of trunks to the same other trunli tinder switch such as the one shown in F ig. 3 from its normal position and cause it'to seek an idle trunk in the fie tt group of trunks to which it has access; the normal position of the trunk fi der switch 311 the brushesexceit'the brush341 are out of engagement witl i' any of thefter} minals of their respectite er'cs'. The- 3111311 341,, however, Will be restihg upon the" t er inin all326 and as sooiies the stepping'nisg net 306 has advan cec'l iii, the; masher pfeviously d escrib eol t cireu'it'will'be clbsedto operate the steppiiig ine'gi'iet' 336' follows battery, winding of the stepping ihegnet 33 ,337,333, 313, 323, 429, 434; 435-, 433, 322, 312, 35 1, 341, 323 :3 ground. Stepping magnet 336 opens zit 337 its own'operetiug circuit and releases, thus rotating the brushes 340 to 345 inclusive one step an anti-clockwise direction to the terminals associated with the first trunk in the roup. The tr'uhlis under control-' of the ttunk findei switch ig. 3) are now tested in the i same generil' manner as were those trunks accessible to the trunlttinde'r switch (Fig. 4) arid the eyc'le'of operations (previously described) ofthe trunk finder switch (Fig. If all the trunks of this gro p 3. 76 busy the brushes 340' to 345 inclusive will rotate step b'ystep' until the last trunk in the group is passed and the twenty-first tern'iinzil in each arc is reached. In this position the stepping magnet will be prevented from releasing by the 'closure of the following holding circuit: bate tery, winding of the stepping magnet 339, 311, 321, terminal 346 iii thearc 334,

brush 344, 347, 473, 446, 445 to ground' A circuit is new closedto operate the step;- ping nieghet 306 as follows: balm- 7,13 134- iiig ,ojtthe steppiug magnet 306, 308 320, 310, 318,319, terminal 348 inthe are brush 345,. 349, 479, 497', 440 to ground. The stepping magnet 306 opens at 308 its own; operating circuit and releases, rotating its brushes 310 to 315 inclusive in ah anticlockwise direction and thus bringing into piay another trunk finder switch not shown with.

V the ot trunks associated -there- This trunk, ail-(161 switchinot shown and the stepping magnet 306 will function in thelgeneral mannerpreviously described for I the-trunk finder switches (Figs. 4 and 3) and the steppingmagnet" 306 will operate and rotate'the brushes 310 to315 inclusive another step to the leads associated with i another trunk finder switch. This "cycle of operatlonscontinues until one of the trunk finderswitches locates an idle trunk to the distant officej shown in Fig. 8."

It should be observed-that when all the trunks to the dist-antofiice have been hunt ed over the trunk finder switch 4) will again come into play and the 'steppingmagnet 426 will advance the brushes 410 to 415 inclusive of the associated" switch to theterrepeated;

ininals as'sociated 'with the firsttrunk in its group and the "From'the foregoing description it is'evident that'when any trunk finder switch ad- ;vancestothe twenty-first po sition,"a c 1r- 'cuit is prepared for operating the stepping 'inagnet of the trunk finder switch. by way of either lead 329,01 339 etc., and the twenty-first terminal of either" are 414 (Fig. 4) or 334 '(Fig. 3); In this position of the trunk finderswitch a circuit is also prepared to operate-the stepping magnet 306 of the steering switch by way of either I ,7 lead 327 and the twenty-first terminal of are 415 (Fig; 4) or by way o'f'lead 318 and the I twenty-first terininalot are 335' (Fig; 3), 7

' It is necessary tot-make sure that the stepping magnet of th'e trunk finder switch is fully operated before the brushes of the V steering switch advance, that is, it-is' neces- V sary to insure the proper operation of the contacts is closed. As the contacts in question are adjustedv so that they donot close until thestepping magnet of thetrunk finder switch is fully operated, itrfollowsthat the steering switch vwill never be able to operate-in advance of theistepping magnet of the trunk finder switch. 7 p In order to insure the proper advance of thesteering switohthe holding circuit for the stepping magnet of the trunk finder switch is controlled by wayof brush .311 of the steering switch. 'J Accordingly the holding circuit 'forI'the stepping magnet of-the trunk finder switch is not opened until the steering switch'hasactually advanced. f So opened by the cycle of operations will be u the holding circuit for its stepping magnet switch,

' Selecting an idle s ender.

Vvhen relay 417 was operatedin thematilong asthe stepping magnet of the trunk. finder switch is operated the 'assooiated. "brushes cannot advance, hencefth'e" trunk I I finder switch cannot return to normaluntil advance of the steering her previously.described afoircuit was closed to operate relay" 455 as follows} battery,

right winding of relay 455, "457', 456 sto variousterminals in the; arcs 550 to 555 inclusive are connected to similarlyvvsituatedi term nals of the corresponding arcs of other. sender selector switches. W hen the sender is "busy-ground will beconnected to 'it's hunting terminal in the terminal are 555 in the following manner: any terminallin ground; It should be understood that the the are 555, common strapping, corresponding terminal in the are (sim-' .ilar to are 555) of the switch which brush is retaining the sender busy, corresponding to 565, leads corresponding to 592, 451, 452, 450, winding of relay corf responding to 460,461,462to ground. Due

to the low' resistance of the winding of re-, lay "460, the busy condition described will 565 is resting upon the hunting terminal associated with a busy sender, relay-455 (Fig. 4) -when operated in the manner previously described will lock over the following circuit: "battery, left"winding of relay 455, 452, 451,. 592, :brush 565, hunting terminal of the'busy sender to ground Re lay 455 operated closes an obvious circuit through the right winding of relay 454 causing the latter relay to operate and lock through its left winding by way of 457 and selector switch as follows: battery, stepping magnet 594, 593, 459, 458, .457, 456 to ground. The stepping magnet .594l'in operating opens its. operating "circuit at its own interrupter contact and. releases, rotating: the brushes not be affected. (Assuming thatthebrush 1 456 to ground, A circuit is now closed to. operate the stepping magnet594 of thesender J ranged to bridge adjacent terminals ofthe are 555 .whenthe brush is rotating, butv to makecontact with one terminal" only when the brush is centered. .Hence as :long,

as the brush 565 encounters a grounded ter-- ininal thefholding circuit for relay 455gwill' I I remain cljosed, and the stepping magnet 594 I will continue to operate-zand release, rotating the brushes 560 to 565' inclusive stepby-step until thebrush 565 is centered upon aterminal in the arc 555'associated with an idle sender. 'In this position the. holding circuit for relay 455 willbe 'openedreleasrelay 455, and opening at 458. the oper- 560 to 565 inclusive one step in an anti clockwise direction. The brush565is ar relay 463 and'the relay 91 closes an obvious circuit to operate relay 913'. Relay 463 operated connects ground by way of 465 and464 tothe winding ofrelay466, but the latter. relay will not operate at this time as'it is short circuited by the ground supplied at 467 by relay 460.. Relay 913 operated connects battery by way of 914,

and1090 to the. windings of the various register relays of the register circuit (Fig. for a purpose hereinafter more fully described.

Theoperation of relay 463 completes a circuit to operate relay 574 as follows: battery, winding of relay 574., 573-, 572, 468,

469, 456 to ground; Relay 5'74 operated extends the 'registrationdeads 627, 628 and 629 (Fig: 6") to the leads: 926,927-

, spectively of Fig. 9. It is desirable to keep these two sets of leads separated until" the calling operator s position and an idle sender I are linked togetherand accordingly relay 574 which,when=operated effects this pur pose", is prevented from operating until the callingioperators position and a'n idle sender 'haveboth been found by the link circuit.

' The operation of relay 463 also completes a": circuit for'the operation of relay470 by of 471 473V and 472 to ground. Relay 4520 operatedextends leads .432 and 433 of the 'outgeing-trunk circuit (Fig; 8) to the leads 920 and 921 respectively of the sender (Fig. .9) to close'in apart the fundamental circuit for a purpose hereinafter more fully described; It is desirable to prevent leads 432' and fro1n= being connected to the leads 920Iand 921 until after an idle trunk circuittand an idle sender have been found and the special function of relay 470is to keep these two sets of leads separated until th'elink cir'cuit'has found both anidle trunk and-an idle sender.

Relay463 also provides a holding circuit I for relay 417 as follows: battery, right winding of relay 417, 496, 469, 456, to ground: and a locking circuit for relay 588 as folloiwss. battery, windings of relays 588 and 5 85,.5011, 584, 489, 496, 469, 456, toground. Relay-.585 does not operate at this time, as it is' short-circuited by the operating circuit of relay 588 previously traced to ground at. 513. of relay 508.

1 Sender waiting.

' Having found the sender a circuit is closed from battery, contact 914 of relay 913 in the sender (Fig. 9), lead 1000 left windings 0r relays 10.121 and 10,11. in series, .1014, 947, brush 964, lead 927, brush .563, 5012, brush 54.1, 503,627, winding ofrelay 616, 640,.

641, 669 to ground operatingrel-ay 616 which loclrsby way of642, 630, 631, to batteryand e inguishesthe No sender lainp 632 ,as'

an indication to the operator that a sender is now attached and thatshe may proceed to register thenumerical digits of the called number. Relays:1011 and1912-donot operin to the thousands digit in which case. a

circuit will be closed as follows to] operate relays 1011 and 1012: solid ground atthe armature 64? ofrel ay 619 654, right1make contacts of key'Nor8', lead'627,=503, brush 501.2, brush563, 9 27, brush 964, 947, 1014, left winding of relay 1011, left winding of relay 1012, 1000,;914 to battery. Relay 1011 which is. sensitive operates whenever by a numerical key closure, av ground condition is connected tolead 927 but relay 1012 which is marginal only operates when sol-id groundis connectedto lead 927 by the closure of a numerical key. I operated looks overlead 10.00 to battery. A circuit is also closed tooperate relays and. 1010 as follows: ground on the armature 647 of relay 619, 654,674, left contact of key 608, 646, 645,-lead 628, 504, brush 542, 5013, 5003,. brush564, 928, winding of relay 922, 948, brush 963, 949, 1015,

right winding of relay. 1010, 1000, 914, to battery. Bela 1010 looks through its windingsin series. elay 1010 operates only'when solid'ground is connected to lead 928.; relay 92-2 is sensitive and operates whenever a ground-.condition'is connectedto lead 928 ire respective of the resistance of the ground condition. I,

It should be observed that whenever a ground condition is appliedtothe lead 926, relay 916isoperated.

Whenever the digit sent is higher than 5, it is necessary to operate one' of the relays 1013, 1023, 1033 or 1043, as the case may be, in order to add five counting relays to the circuit so as to transmittheproper number of impulses to the distant mechanical ollice (Fig.8);

Since the thousands digit is 8, it'is'necessary to operate relay 1013.. This is accomplished in the following manner: from battery on the make contact 9140f rela Relay 1011 Y y 913, over the common batterylead 1000,

locks under control of relay I 'eration of relay 922 also closes-at 966 an winding of may 1013, first tarnish of obvious circuit by way of lead 967 to operate the stepping magnet 956. So long as the "969, 977, 9 7. and 966 in parallel with the tact by "way of 9 key 608 is depressed, relay 922 remains op- "erated and the stepping-magnet 956 cannot release but as soon as key 608 is relay 922 releases. Y

Relay 917 also operated byway of 968,

released,

stepping magnet 956 to ground under con-,

trol of relay 922. Relay 917 operated locks by. way of 968,969, 977, 967, 978 to ground and connects ground through its make 0011- 78 and 967 to the winding of stepping magnet 956 to insure the step ping magnets proper operation though relay 922 only operated -momentarilv when the key 608 wasfdepressed. Re-

lay '91? cannot release. until the stepping magneti956 opens itsjinterrupter contact 977 at the end of its operating stroke thus insuring the proper operation of the stepping magnet 956 no matter how' short a spaceot-time the numerical key 608 is depressed by the operator. When the step ping magnet 956 opens its interrupter 0011- 1 tact 977 the loclring-circuit forrelay 917 is opened and this relay releases opening the holding; circuit for the stepping magnet 956. which likewise releases advancing its brushes 960 to 965, inclusive, one step in an anti-clockwise 'direction substituting at brush 963. relay 1020 for relay 1010; at brush 964 relays 1021 and 1022 for relays 1011a-nd 1012 and at brush 965 relay 1023 for relay "When key 608 is released, ground byway of lead 927, brush 964 and leads 947 and 1014 is removed from the left winding of relay 1011. and relay 1012 now looks v:trom battery on lead 1000, left winding of relay 1012,. left winding of relay 1011, 1014 and right winding ofrelay 1012 to ground.

Ni e are now ready to send the'hundreds digit which in this case is digit 1 and accordingly, numerical key 601 corresponding to the digit 1'is depressed, A circuit is now closed to "Operate relays 91.6 and 1020 as follows: ground at armature 647 of relay second terminal of are 953, 1090, right wind ing of relay 1020,1000, 914 to battery, Be

lay 1020 locks through its windings in series. Relay 91.6'operated closes a circuit to operate relay 917 as tollowsi battery, winding otrelay 917. 968. 969,977. 967, am ground. It alsocloses a circuit to operate winding of stepping magnet 956, 967, 959

Even I erating stroke," when 917- releases. 'This circuit arrangementinsure's the proper op- I eratlon of stepping magnet 956-1ncase the relay 9 16 isonly operated moment'arily by e the momentary depression of 'key 601.

When key 601 is depressed, a circuit is also closed to operate 1021 as ,followsz I ground at armature 647 of relay 619, 654,

resistance 650 right contact of key 601, 680,

627, 503, brush 541, '5012, - brush 563, 927,

brush 964, second terminal; of are 954, 1eft windings of relays 1021 and 1022 inserie's,

1000, 914 to battery Relay1022 is margileases. pWith "relays 9'16 and 9:17 released, the holding circuit for thestepping magnal and'will not operate chietofthe high 're- I ;sistance of the resistance "650.111 series' 'with it butlrelay 1021 which is sensitive operates net 956 is opened andthe stepping magnet releases advancing the brushes 960 to 9.65,

, inclusive, another step in'an anticlockwise direction were third terminal 0f 'e' aoh of the-arcs 950 130 955 inclusive? '1 the thousands The operatorhaving I p and hundreds registration, the sender will now proceed {to transmit impulses representing the thousands digit overthe fundamental circuit to the distant mechanical 'oflice (Fig, 8) to set'the incoming selector (IS) thereat'. This operation will be hereinafter more fullydescribed-f The key 605corr'espond'ng to the d1git5 is now depressed in accordance with thetens digit of the desired number closing a. circuit to operate relay1031 as follows ground atarmature 647' of relay 619, 654, resistance 650, right contact of key 605, 680, 627, 503, brush. 541, 5012, brush 563,927, brush 964, third terminal of are 954, left windings of battery. Relay 1031 which is sensitive operates'hut relay 1032 which is marginal does not operate due to the high resistance of resistance 650 in series with it. Relay- 1031 operated, locks'through its right winding by wayof lead 1000 tobattery, With the'key 619, 654, 674. left contact of key 601, 644, 629, 505. brush 543. 5014, 5001, brush 562, 926Qwindina' of relay 916, 948, brushf963,

605 depressed, a circuit is"alsoclosed fto'opr crate relay 916'as. follows: ground at armature 647 of relay619, 654,resistance 651, left contact of key 605," 644, 629, 505, brush .543,

5014, 5001, brush 562, 9 26, winding jofp relay 916,-. 948, brush 963, third terminal of are 953, right winding ofjrelay 1030, .1000, to hattery.i- Relay 1030 which is marginal does not operate due' to the:jhighifresistance "of the coil .651 inserieswith it. Relay916 operated operates relay i917 and, stepping magnet 956 which functionsfin the manner .relays1031 and 1032in series, 1000, 914, to

previously described, and when relay 916 releases by the release of key 605 and relay 917 by the complete operation of stepping magnet 956, the circuit through the stepplng magnet is opened and it releases advancing I its brushes 960 to 965, inclusive, to the fourth terminal of each of the arcs 950 to 955, respectively...

We are now ready to. send the units digit which in this case is the digit zero and accordingly numerical key 600, corresponding to the digit zero, is depressed.

The key 600 depressed operates relay 1041 as follows: ground, armature 647 of relay 619, 654, resistance 650, right contact of key 600, 680, 627, 503', brush 541, 5012, brush 563, 927, brush 964, fourth terminal of are 954, left winding of relays 1041 and 1042 in series, 1016, 986, to battery. Relay 1041 which is sensitive operates but relay 1042 which is marginal does not operate due to the high resistance of resistance 650 in series withit. Acircuit is also closed to operate relay 922 as follows: from ground at armature 647 of relay 619, 654, resistance 651,

left contact of key 600, 645, 628, 504, brush 542, 5013, 5003,brush 564,928, winding of relay 922, 948, brush 963, fourth terminal of 953, right winding of relay 1040, 1000, 914 to battery. Relay-922 operates but relay 1040 which is marginal does not operate due to the high resistance of the resistance coil 651 in series with it. Relay 922 operated operates relay 917 and stepping magnet 956 in the manner previously described.

When key 600 is released, relay 922 releases. When the stepping magnet 956 is fully operated,-relay 917 releases and the holding circuit for the stepping magnet 956 is openedallowing the stepping magnet to release andadvance the brushes 960 to 965, inclusive, onev step in an anti-clockwise direction to the fifth terminal of each of the arcs 950 to 955, respectively.

Sending impulses.

- An important feature of this invention is that after two digits (the thousands and hundreds) have been registered, the sender will proceed to transmit the first digit and for each additional digit recorded, the sender will proceed to transmit impulses corresponding to the next succeeding digit over the fundamental circuit to the distant mechanical oflice (Fig. 8). One digit, however,

4 is always held-in reserve by the sender until all the digits have been registered by the operator.

When the operator inserts the plug of the cord 10 in the jack 807 in the manner hereinafter described, certain changes occur in the sender indicating that all the digits transmitted have been recorded whereupon the sender proceeds to transmit the digit which has been held in reserve up to that time. This will be hereinafter more fully described.

After the second digit (hundreds digit) was recorded, the brush 960 of the recording switch was advanced to the third terminal of the arc 950 closing an obvious circuit to operate relay 900 through its right winding to ground at the brush 960. Relay 900 operated looks through its left winding by way of lead 987, strap terminals of the arc 952 of the recording switch, brush 962 to ground. Under certain conditions, by way of lead 988 and the strap terminal of are 975 of the sending switch to ground at brush 985 in a manner hereinafter more fully described.

Thousands selection.

We are now ready to transmit impulses over the fundamental circuit to the distant office to set the selector. switches thereat providing the fundamental circuit is closed and, accordingly, we must now test the fundamental circuit before allowing any impulses to be transmitted thereover. A circuit is closed to operate relays 929 and 811 as follows: battery, right Winding of relay 811 (Fig. 8) trunk conductor 823, 432, 422, 498, 498, brush 561, 921, 989, winding of relay 929, 920, brush 560, 5015, 497, brush 433, trunk conductor 822, left winding of relay 811 to ground. Relays 929 and 811 operate after the circuit is properly closed. The function of relay 811 will be hereinafter more fully, described.

telay 929 tests the incoming selector (18) (Fig. 8) as soon as the trunk circuit and an idle sender circuit are found. Relay 900 operates after the second (hundreds) digit of the number of the called line has. been recorded in the sender and the brushes of the recordingswitch have advanced to the relay 900 may lock third terminal of each ofthe arcs 950 to ing circuit of the stepping magnet 976 is opened and the brushes 980 to 985 inclusive, accordingly remain atrest upon the second terminal of their respective arcs. A circuit is now closed to operate relay 946 under control of the interrupter 937 as follows: battery at the armature of relay 913, 986, 993, the second terminal or arc'971,

984 resting upon the

Images