US1646262A - schwartz - Google Patents

Description

oa. 1s, 1927. 1,646,262

M.' scHwAR'rz AUTOMATIC TELEPHONE SYSTEM Original Filed Dec. 16, 1922 6 Sheets-Sheet l v 1,646,262 M. SCHWARTZ AUTOMATIC TELEPHONE SYSTEM Original Filed Dec. 16, 1922 6 Shee M. SCHWARTZ AUTOMATIC TEIJEPHONE SYSTEM e sheets-sheet s Original Filed Dec. 16, 1922 oct 1s. 1927-. V1,646,262

M. SCHWARTZ AUTOMATIC' TELEPHONE SYS TEM Original Filed Dec. 16, 1922 OOOOOOOOOOOOOOOOOO FQ un un w Q 'u fr hgz Enh-MEE .Z MHT oct. 18 1927. 1 6262 M. SCHWARTZ AUTOMATIC TELEPHONE SYSTEM Original Filed Dec. 16. 1922 6 Sheets-Sheet 5 -Imrenur M1 haal Enhwarz Oct. 18,l 927 M. SCHWARTZ- AUTOMATIC TELEPHONE SYSTEM original Fi1ed'Deo.'1e, 1922 6 Sheets-Sheet s Patented Oct. 18, 1927.

UNITED STATES 1,646,262 PATENT OFFICE.

MICHAEL SCHWARTZ, F CHICAGO, 1ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRIC INC., 0F CHICAGO,ILLINOIS,' A CORPORATION 0F DELAWARE.

AUTOMATIC TELEPHONE SYSTEM.

Application filed December 16, 1922Sera1 o. 607,270. Renewed January 22,

The present invention relates in general to automatic telephone systems, but more especially to multi-office automatic telephone systems; and the object oi". the invention is 5 to produce a new and improved director, or registering, translating, Y and sending apparatus for controlling the automatic switches, and new and improved trunking arrangements controlled by said director.

The present invention may be considered an improvement on or a modification ot the director systems disclosed in British patents: 193,964 (complete accepted March 1, 1923), 194,580 (complete accepted March 15, 1923),` 200.484 (complete accepted Aug. 1, 1924), 194,427 (complete accepted March 15, 1923), which patents correspond, respec-` tively, to the United States applications: Serial No. 538,551, tiled Feb. 23, 1922, Serial No. 547,866, filed March 29, 1922. Serial No. 573,175, tiled July 6, 1922, Serial No. 598,u 239; filed Nov. i, 1922. f

In the said application, Serial No. 538,551, filed February 23, 1922,'an apparatus'ot the above character is illustrated and described. The director shown .in `that application is comlnon to a large number ot subscribers and is adapted to be connected to a tirst selector trunk when such trunk is taken tor use by a calling subscriber, whereupon registering devices in the director respond to the impulses from the subscribers calling device and record the various characters, letters or digits, constituting the called telephone number. As soon as the irst three characters, or letters are registered, a sending device is setv in motion` andtransmits series of impulses in accordance with a code derived by translation `trom these letters. The code impulses operate a series oi selector switches to trunk the call to the desired oiiice. and kthe sending device then transmits the registered digits in the called telephone number to the selected office without translation to operate other selectors anda connector to complete the connection to the called line. Means is provided whereby the transmission ot yany series ot impulses, eX-

cept. .the first` is made contingent upon the con'ipletion of the trunk hunting movement in the selector which responds to the preceding series ot impulses. f

Inthe said application, Serial No.. 547.866. tiled March29, 1922. an apparatus ot similar character isillustrated `and described,

the principal feature of improvement being that the directors are divided into groups, and .director selectors are inserted between the first selector trunks and the directors. This arrangement reduced the number ot different calls handled by each director to approximately one-tenth of the total number, whereas in the former system the director had to be capable of handling all calls.. The construction of the second director was, therefore, much less complicated and its cost was correspondingly reduced. One saving in particular, which may be mentioned. was brought about by the use of only one two-motion Strowger switch per director, instead ot the nine which were formerly required. A second feature in connection with the second director was the elimination of the revertive control of the sending switch by means of which the starting of the sending switch to operate any selector was made contingent on the completion oi the trunk hunting movement of the preceding selector.y Instead of the revertive control, a standard time interval of approximately one-third of a second was inserted between successive series of impulses, this time interval being slightly longer than the maximum hunting time .ot' a Strowger se-V lector switch. i

The -director forming the subject-matter ot' the presentfinvention resembles the one last referred to and operates according to the same general. principles. For the sake of simplicity, the present invention is shown in connection with a multi-ottice telephone system, .such as may be found in exchange areas ot. `moderate size, where there Will never be more than one hundred ottices and, for `this reason, the director selectors may be eliminated. .The director, as shown, as common to a large number of subscribers and is adapted to be seized by a director selecting line switch associated with a trunk, when such trunk is taken for use by a calling subscriber. It is to be understood that the invention is not limited to the Specific structure shown, but is equally as applicable when applied to telephone systems of larger size.

According to the principal feature of improvement, director controlled switching line switches are inserted between the trunk equipment vand the first selectors. In general, the function of the `switching line switch is merely that of'selecting an idle first selector, after which the connection is set up by lthe director in the usual manner.. In the special case represented by a .connection to acalle'd substationv located within the same office as thecalling substation, the director, as soon as'the critical character has been received, willl cause associated switching line switch to release .the iirst selector and at Ithe saine time select 'an idle local third selectorl in the ordinating office. The director ,isy Athen releasel` and becomes available to Aother director -select-ing line switches. The Afurther operation of t" we dial at the calling lsubstation serves to directly g operate the switches in `the local office, thus completing the connection to the called iine. From the foregoing, it vvvill oe :seen that the invention provid-es 4means whereby, on caille between stations in the -same oice, the connectiornl may be trunked ydirectly from ai switching linegswitc'h to a local third selector, thus releasing the first selector' A'previously seized, as a res-ult 'of which 'this 'switch diagrams of a vcomplete director.

Fignre '6 isa trunking diagram of the Lsystern which is shown in detail in Figs. l to 5, inclusive. .4

Figure 7 is ia fron-t 'View of the subscribers calling `devi-ce showing vthe numbering of the dial. s

Figure 8' isV a layout showing how sheets i to '5,' inclusive, should be joined together.

JIt 'will beadvi-sable first to consider the tunking layout, `Fig. "6, as an understanding of 'this will assist in the explanation of `the rest off the drawings. It may be a't the'outsetwtli at the illustration of `the trnnk ing is only fragmentary. Each olicein the system lis provided `with uand second selectors 4for handling 'the interolice trunk-v ing, and in any `given oiice the trunk lines extending tothe other oiiices are, in general, taken from the banks .of the second selectors. Assumingthat a group of interolioe :trunk lines 'is teiten for a .second :selector level, these trunk lines would entend by way of rrepeaters to incoming third seiectors at fthe terminating office, and .connections would Vbe completed at .that oilice by 1means rolf the incoming third selectors, fourth selectors, Vand connectors.` An @arrangement similar to is' shown diagrammatically in Fig. (5. The subscriber at isubstation A in Bryant ottico 'may set up ,a lconnection with the subscriber at substation A" in the Sunnyside foflice by means of the primary andyoecondcry line switches C and C2, a director selecting line switch C3 and a director, which director is lcapable .et registering thecalled. number '.SUnnyside 234.5 and operating the switch` ing line switch C4, the first and second .sclaedoons E and E2 in the originating oiice, and the incoming third selector E3, the

yfourth selector E5, and the conncctor H in manner: The subscriber at substation A may set vup the connection by means of the pri# mary and secondary linee switches C and C, a directo-r selecting line switch 03, and a director, which director is capable of registering the called number BRyan't 2W5A=and Y giet-ung for the ytime being inermi-Chius line switch C, operating thetirst and second selectors E and E2, 'the `local ltlhird selector E, the 'curth seiector E7', and the foonnec tor H2 to complete the connection. The

cults in the release of the irst selector EE, ,Y

thus .making it available @for use in ertabiislr ing other connections.V

n Fig. 6 a trunk is shown extending 'fumi the bank of the secondary rotary line switch `to a switching iine'switch C". A relay equipment, indicated by A.the reference charmater D, vis included .in the trunk which is Vnormally' open at this point.v From therelay equipment D tlie incoming and outgoing sections off the trunk exnd vto ithe .director selecting line switch C3.. When the calling subscriber seines the twink line, the director selecting line switch C is operated to'select an idle director. Whenthis 'is accomplished, the incoming and outgoing sections of the trunk are extended to the :selector di rector.. The director' then causes the :switch-ing line switch C to 'select an idle iinst selector. The `director is nonl .in ridiness to register the letters and :digits of the called number, and to rovide for the transmissionfof the requin series of impulses, by the director to .operate the train of :switches by means of which the connection is completed;

apparatus in Figs. l to 5, inclusive, may now be explained more in detail. Fig. l shows the detailed circuit arrangements of the relay. equipment D, s'witchin :line

switch-G4 and the :first selector trunk w'iich is lis depicted in Fig. 6 together with the director selecting line switch C3. The trunk conductors 13, 14, and 15 extend from multiple sets ot contacts in the banks ot secondary rotary line switches such as the line switch C2, one of which set of contacts is indicated by reference characters 10, 11, and 12, by way of the relay equipment D to the switching lineswitch C4. The relay equipment D comprises three relays, and the line conductors of the trunk are normally open at the contacts of one of these relays, both the incoming and outgoing sections of the trunk being indirectly extended to the director selecting line switch C, which is located below the trunk relay equipment D.`

The director selecting line switch C3 is a step-by-step rotary switch of the type in which the wipers move in a forward direction only. In further explanation, it should be stated that this switch is ot the type in which the wipers are advanced when the stepping magnet retracts its armature, rather than when the stepping magnet is energized. The trunk conductors 172, 173, 174, and 175 extend from multiple sets of contacts in the banks of director selecting line switches such as the line switch C3, one of which set of contacts is indicated by the contacts 168, 169, 170, and 171, tothe director indicated in Figs. 2, 3, 4, and 5.

The switching line switch C4 is a step-bystep rotary switch of thetype in4 which the wipers move in a forward direction only. In this connection, it may be. stated that this switch is of the type in which the wipers are advanced when the stepping magnet retracts its armature, rather than when the stepping magnet is energized. In further explanation, it should be stated that the stepping magnet operates a single shaft to which mounted a primary set of wipers indicated by the reference numbers 75, 76 andv77 and a secondary set of wipers indicated. by the reference numbers 117, 118, and 119, each set of wipersvbeing designed to engage the contacts in an associated multiple bank. One set or the other of these wipers will be connected to the trunkconductors 47, 48, and 49 of the switching line switch C4, depending upon the energization or deenergization of relay 02. The trunk conductors 104, 105, and 106fextend from multiple sets of contacts in the primary banks of switching line switches such as the line switch C4, one of which set of contacts is indicated by reference characters 101., 102, and 103, to the first selector E. The trunk conductors 123, 124, and 125 extend from multiple. `Sets of contacts in the secondary banks of switching line switches such as the line switch C", one ot' which eet of contacts is indicated by reference characters 120, 121, and 122, to the local third selector E6.

The first selector E and the local third selector E6 are vertical and rotary switches of the Strowger type, and each has access to 100 sets of contacts arranged in ten horizontal rows or levels. The circuit of these switches is a standard two-wire circuit of well-known type and for that reason has been shown only in part.

One of the directors is shown complete in Figs. 2 to 5,-inclusive, and comprises the master digit controller M, Fig. 2; the B and C impulses register J, Fig. 4; a thousands register M', a hundreds register M2, a tens register M3, a units register M4, all of which are shown in Fig. 2; an impulse sending switch S, Fig. 3; a sequence switch S', Fig. 5; and an intermediate distributing frame I. D. F., Fig. 4.

The master digit controller M and the four digit registers M to M4, inclusive, are simple ten-point step-by-step switches, each ot which are provided with an operating magnet, a release magnet, and a set of off normal springs which are operated when the switch wipers are advanced out of their normal position.

'Ilhe B and C impulse register J is a Strowger switch oit the vertical and rotary type having 100 sets ot' contacts arranged in ten horizontal rows or levels. The operating and release magnets of the switch J are controlled over conductors coming from the master digit controller M, Fig. 2, and, consequently, the switch requires no relays. Four wipers, indicated by the. reference characters 306 to 309, inclusive, are shown to the right of the operating magnets in Fig. 4, which also shows the first tive sets of contacts in the third level of the. bank tov which these wipers have access. All of the contact sets in the bank which corre pond to working exchanges, of which correspond to exchanges which it is anticipated will be installed, are wired to terminal sets on the leithand side of the I. D. F., as shown in the case of the second and iith contact sets.

The right-hand side of the intermediate distributing trame consists of fifteen or more bus-bars, each having a plurality of terminals in order to provide facilities for crossconnecting any terminal on the left-hand side of the I. D. F. with any bus-bar. The iirst nine bus-bars correspond to the nine digits, 1 to 9, inclusive, and are so marked in the drawing. These busebars are connected in multiple with the banks of the register switches M to M", inclusive, and withy the bank of the sending switch S, as is shownin Figs. 2 and 3. Bus-bars X, Y, and Z provide for automatically advancing the sequence switch S` on oiiice codes which have less than the maximum number ofseries of impulses; bus-bar SlV is a sliecialswitching bus-bar used to control the 4switching through at the trunk test contact with which the test wiper 76 is in engagement, theswitching relay 57 will be short circuited, Qand'the stepping magnet 68 will be operated to advance the switch wipers into engagement with the next trunk. If the next trunk line is busy, the same operation will be repeated and the stepping magnet 68 `will continue to operate in the manner of a buzzer to advance the switch wipers step by step ,untill an idle trunk line is encountered. However, if the trunk line with which the wipers of the line switch are associated is idle, there will be no ground potential on the test Contact engaged by the test wiper 76, and the switching relay 57will not be short circuited, but will be immediately energized in series with the stepping magnet 68, thesaid magnet remainingkinoperative due to the high resistance o1 the switching relay. Assuming that when the line relay is energized in the present case, the first selector E is idle, then switching relay 57 will be immediately operated when its circuit is completed by the a said line relay, as pointed out under the second alternative above. On attracting its armature 56, theswitching relay disconnects the test wiper 76 from armature 64 of the line relay and connects it instead to its own upper terminal, the ground potential which is thus placed upon the test contact 102 being effective 4to render the trunk line busy to other calls. In addition to the foregoing, relay 57 at armatures 54 and 49 disconnects the line conductors 50 and 53 from the line relay 61 and ground, respectively, and extends them by way of armatures 69 and 71 ot relay 62, Wipers and 77, bank contacts 101 and 103, conductors 104 and 106, and armatures 135 and 136 of relay 137 to the upper and lower windings of the line relay 107 ot the first selector 'FC l/V hen the trunk isextended to the line relay 107 as previously explained, this relay is energized and at armature 138 closes acircuit for `the slow-acting release relay 108.V

Upon energizing, relay 108 connects ground to the release trunk conductor 105 at armature 109,'thereby closing a holding circuit ior the switching line switch C4, which extends by way of the said conductor 105, test contact 102, test wiper 76, resting contact and armature 70, armature 56 and its vworking contact, windingof the switching relay 57 and the winding of the stepping magnet 68 to battery. This hold ing circuit is established before the slowacting line relay 61 has had time to deenergize, and is effective to retain the line switch C4 in operated position throughout the connection. It will be seen that the holding groundisextended rto conductor 51 by the operation/oi armature 55.

Returning now to the-circuit changes produced' in the director-by the operation of the switching relay 157 of the director selecting line switch C3, it may be said that ground potential is placed on holding conductor 172 and, since this conductor is connected by way of normally closed contacts at karmatures 525 and 527, Fig. 3, it follows that relays 510 and 511, Fig. `3, will be energized.` Relay 511, on energizing, removes Vground from the` upper bank ot' the sequence ing line switch G3, is the preparation of an impulsing or control circuit for the vertical magnet 303 of the B and C impulse registery J, Fig. 4, which may be traced as follows: from ground atthe resting contact ot armature 24, Fig. 1, by way of the working contact of armature 160, wiper 166, bank contact 170, conductor 173, armature 538 and its resting contact, conductor 202, the winding of they low resistance slow-acting series relay 207, Wiper 218 of the master digit controller M in irstposition, conductor 301, and the winding of the vertical magnet 303 'to battery. The preparation ot this circuit places the B and C impulse register J in condition to receive the firsttwo series of impulses from the calling line.

As a further result. of the energization of the switching relay `157, the conductor 52 associated with the switching line switch C4 is extended at armature 158 to wiper 164 and is thus connected by way of bank contact 168 with conductor 175; this operation is without effect at this time.

When the calling subscriber operates his calling device for the first letter in the called number, or the letter S, three interruptions will be produced in his line circuit and the line relay 23 in the trunk relay group D will be deenergized three times. Accordingly, the line relay 23 will transmit a series of three impulses over the previously traced operating circuit to the vertical magnet 303 of the B and C impulse register J. In response to these impulses, the magnet` 303 operates to raise the wipers 306 to 309, inclusive, step by step `until they stand opposite the third level of bank contacts.

The slow-actingrelay 207 in the master digit controller M isenergized in series with the vertical magnet 303 of switch J, and re- .tains itsarmature 215 in operated position throughout the series of impulsesl At the working contact of armature 215 a circuit is completedfor :relay 208 which is thus maintained also. At the end ofthe series of impulses, relay 207 `falls back and breaks the ei`renit of relay 208,V whereupon the lat; ter" relay clveenergizes also.l Sinee, relay 208 vis slowlaeting, however, it will net be clee-Iflergizecl-V until an instantl after yrelayv 207 hasretracted its armature ancla momentary impulse of 'ein-rent will be ytransmitted to ste-pping'rnagnet 2'12 of' the master digit eontmller M from ground by Wayfo'l' armap tureand its`v resting eontaet, armature 216V zzn-dits Working Contact, and the Winding of the'stepping magnet 2l2'to battery.

vBy the operation of ythe stepping-magnet 2.12, Wipers 218 antlf219 second positien.-

l Then the eall'ng subscriber' dials the next letter in the .called number', or the letter U, five interruptions will be produced"t his are' advanced into n line eirenit, and' the line relays23 of the trunk relaygroup D vvillv be' ldeenergized five times.- This relay, aeeorrlmgly, trans# mits liveimpulses of' current over-the previonsly traced operating Circuit, and now,

sinee the Wiper 218- or" themaster digit eontrnller standing in second position,

these eircuit impulses-Will? pass over con- Vvcluetor 30291161 through the rotary magnet 304i By the resulting operation of the rotary magnet` Wipers 30S-to 309, inclusive,

Vare atlvaneecl liv'e'stepsl in arotary (lireel' tion and are brought to rest in engagement with the fifthl set oflz' @onta-ets in the third level.'`

i During'the rotary movement of the BandAVV C impulse register J, the slew-acting series' relay 2070154 theinaster cli-gift'controller` M is energized the same as-it wasdinfingthe vertical mevemenand completes a' Circuit for the slow-acting relay 208;.'v At' the end of theV rotary movement,l these twoV relays' 4cleenergiz'e instant apart an thus eooper# ate in .transmitting an nnpnl'se oit current to the stepping magnet 212 ofthe master digit controller M, the- Wipers of which accordthe rotary maglie/tf off the' and vimpulse ingly advanee to vthirel position; At Wiper 2118i the opera-ting oir-control Cirenilt4 @om-ing froml the director; seleeting linev siviteh over Conductors' 17 and 202 is 'shifted' fromv "register J to the stepping nifagiiet-227` of the thousanelsfregister M-, While 'atWiper 219L afgronncl is plaeetl onstarting concluen torino; -v

Responsive to' the grouncling oit the start xviire400, the sending Vswitch 'Sfbegins Vto transmit' impnlsesfmf accordance withn the OllieeI eodewhieli has been el'eterminedon by the'dialling ofthe first three letters oftthe .called number, Alon-ty ift isathouglit best te defer the explanation of these operationsV in( order tol 4permit anA` explanation ofthe operation VOf theregister switches M tofMiinelusive,`

in registering the four digit-sof the' called' numbers. fWhen lthe eallingsubseriber 0p-y eravtes his callingclevrce in aeeorclancegwith digit' 23 off the ealleet nmnher, the? line lattract ,rl

relay 2301? the trunk relay'equipment responds in the usual manner and transmits @magnet 227 of A tino impulses to the steppin thethonsands register M'. ythe operation ofthe stepping magnet 22.7', Wiper" 244 is acl-l vanoetl'two steps into engagement with the seeonel Contact-in' its assoeiated'v bank, When the lswitch leaves its normal. position, the. off normal springs are shrftedand spring' byy engagingnits Workingfeontaetr pre# staterl, eneifrizeil: in series with the stepping magnet 227 and holclfs itsffarmature 2355 (turing the stepping' movement of the register sivnh inorder to' prevent',v the ,tor 4210 from being grounded until Y the registration of the digit' is completedy f The sloW-aeting series relay 207 is falso energized in. series with the stepping1 mag-v net' 22%Y Vand inv 'conjunction with relay operates. te fansmit another impulseof veurgmng magnet 212* of the njas;r

rent to the st ter @Eight een verliere-luy wipersl 218 and' 2191129 advanced troller at the' proper time;k

tothefonrth. pesi: VWiper 2148', inshift-L ingfw-inr thi. i control 4eirrnit from; the stepping' magnet 2211oftlieregster switeh M tothe stepping..

magnet 22Go 'the hunch-eds register switch M2; No eiren-itehanges are broughtabout bythe: gtnrtlier mevemfent of Wiper 219,! since' y .cantante 3l to 10, inelu'sive, in`r` the bank assoeiateelr-With y this. Wiper aremnltiplecl to! getherfv lt may be stated that Wiper`219 should. preferably be so constructed that When'aellvaneecl from` eontaetfto: Contact! it will engage a neny eon-taeteach time bef-ore' it clisengages the preceding one;

`It Will be unnecessar'yto rleseribein Vrni-l Y nnte detail how the other 'three register f 'Y switerhfe's Ml?, Mqand M are operated yresponsive to the[clialling of" thegremaining three fllrgitserf' the mifmber.'` It willv be s'f- .to fourth position., shifts the" will transmit three impulses :ofj 'eurrvent` tl'irongh relaysl 207 and 230, and through'the )pingv magnet226l in series,` Wherebythef v saidlstepping magnet isoperated to `advance Y VWiper' 245 into .engagement with the, third,-

eontaet in its bank. At the enel of theV step4 ping ,moyemen tpffielay i 230, Whioh f holds' upf4 itsarmature 234 "during the operation 'of the 'register-"sfwrteh, cleen.eiggfizes' and' connects gronndl to conilluetor422'. At the Same' time, v

theslowacting relays 20'? aucl 208 transmitV annnrplrlse to the steppinfgmagnet 2120115 the masterdigit controller inorrleroto advalreep the wip-'ers 2218i and? to fifth vposition. In a ,manner similar tothe Vabovp-,rrV

when calling. subscriber VVVdial's theV tens dhfgit 4 and the: units digit-5, as series; of kforni memes4 impulses is Afirst transmitted to the stepping magnet 225 oi the tens register M3, and a series of live ,iinpulsesis then transmitted t0 the stepping magnet 224 of the units regis-- ter M1, it lieii'ig understood, of course, that the control circuit shifted from magnet to magnet 224 at the proper time py wiper 218 oi the master digit controller i lViiier 246 oit register switch h43 is accord-- letters of the number has been `dialled, the

actual starting of the sending switch being accoinplishedby the grounding of the starting wire 400 when the wiper 219.. oi the master digit vcontroller M arrives in third position. The code in accordance with which the call is trunked to the S-Unnyside oiiice is (5S, as may `be perceived from an inspection oi the trunking diagram, Fig. 6, and accordingly, the fifth set of contacts in the third level of switch J, which set oil contacts is selected by dialling the letters SU, is so cross-connected at the intermediate distributing trame as to cause the transf mission oic two series ot' impulses, the first series comprising siX interruptions and the second series comprising three interruptions. Mlorc in detail, terminal is cross-connected to bus-bar No. 6, terminal 332 is lcrois-connected to bus-bar No. 3, terminal 831 is cross-connected to bus-bar Y, and terminal 330 cross-coiinected to bus-bar XL These cross-connections will ncause the required series oi. impulses to be transmitted by the :',eiiding switch kS, as Will be understood shortly. A c.

Conductor 400 extends to the sequence switch S, Fig. 5, where it is connected to wiper 40,4 and to the first four contacts in` with bus-bar No. 6, andthence by Wayof conductoivBGG to the No. 6 contact in the bank of stop wiper 514 of the sending svvitcli. At the same time that the above circuit is completed, a circuit is completed tor the impulsing relay 507 of the sending switch over the following path: from the grounded conductor 400 by way of wiper 405 in Atirst position, conductor 425, resting contact of armature 519 and the said armature, resting contact of armature 540 and the `Said armature, winding of the impulsing relay 507, and through the interrupter I to battery. The interrupter I is continuously driven and consists ot any suitable cam arrangement for intermittently connecting battery to the relays such as relay 507 at the rate ot about` ten times per second. lVlien this circuit is closed, there'lore, or shortly afterwards, depending upon the position of the interrupter I, relay 507 is energized and opens the impulsing contact at armature 5223, this opera-V tion being of iio effect, however, due to the fact that the contact at armature 523 is short-c-ircuited at armature 520 of relay 50G. Relay 507 also closes the circuit of stepping magnet 515 at armature524, and the said magnet is energized. lVhen the circuit ot relay 507 is broken bythe interrupter I an instant later, the relay falls back and again closes its impulsing contact at armature 523, and breaks the circuit of the stepping magnet 515, which thereupon retracts its armature and advances the wipers and 514 one step. A circuit is now completed for relay 506 by wiper 513, and this relay, upon energizingremoves the short-circuit from the impulsing contact 523 at arii'iatur-e 520, prepares a locking circuit for stop relay 505, at armature 521, and at armature 522 connects ground to conductor 426, thus conipleting a circuit for the stepyriing magnet 402 of sequence switch S. Magnet 402 is accordingly energized, but without aifecting the position of its wipers, which like the wipers of the sending switch are advanced when the magnet retracts its armature. The second time the` circuit oi relay 507`is closed VJ\, by interrupter I, the said relay close the circuit of the stepping magnet 515 as be,- fore and also, since relay is now energized, it momentarily opens the circuit oi'f relay 27 of the trunk relay equipnieiit I) at impulsing contact 523. Then the circuit ot relay 27 is broken, it in turn dceiiergzes and momentarily opens the circuit ot line relay 107 of the first selector E. lil/*lien the circuit of relay 507 is broken by the interrupter. it deenergizes and breaks the circuit of the stepping magnet 515, which retracts its arm ature and advances ite;y wipers 513 and 514 one 'more step, thus bringing the stop wiper 514 into engagement with the No. 1 contact in its bank.V It will be seen that the se riding switch S is caused to make an initial or false step before it` actually begins transmitting impulses, and this, it may be stated,

lui)

izo

isfdone in orde-r to insure that the first im pulse transmitted ywill of the standard length.

The energizations and deenergizntions Voit relay 507 continue in quicksuccession under control of the interruptor I. Alter the second deenergization, which terminates the Iii-st impulse or interruption oiy the control! circuit, the stop Vwiper 514 is advanced into engagement with. its No. y1 Contact, stated, after" the third .dcenergization wiper 514 isadvanced into engagement witli its No'. 2 contact, and so 011,. until finally after the sixth interruption has been produced', the" stop wiper is advanced into engagement with the No, 6 contact. digit in the' interet-lice code is- 6, therequired number olf' impulses have now been transmitted to the iirst selector E by nie-ans' of the' relay 27 of the trunk relay equipment D. As previously explained, the No/(S fcontact in the lower ban-lr oi the ser-Kline,r`

' the stop relay '5105.

switch isggrounded at Vthis time, and when the stop wipe-r 514 comes into engagement`l tary circuit, the stepping magnet 515 oper-VY ates as a buzzer and advances the wipers of ,the sending switch to normal position. n

As a further result oi the energlzationof n theY stop relay 505, the circuit of the stepping magnet' 402 oi the vsequence switch S is broken at armature-.518, andV the said magnet is deenerg'ized, thus advancinfrtlie sequence switch wipers Vtosecond position.. As aV result of' the ino-vement oi sequence switch wiper 404y from iirst to second positio-n, ground'is removed from the No. v6

Vcontact tliebanl of the stop-f wiper 5M and is connected tothe No'. 3 contact, the

new circuit being traceable' from the ground,- ed startingl conducto-r 400 by way of wiper 404 second position, conductor 412, wipe-r V307 of regis-ter switch-J and the contacten- Vraged'by said wiper, terminal 332 a jumper connectingV this terminal with' bus-'bar No, 3,

= and conductor 365 tothe No. S'icontact in the bank off''he stop wiper. Thea-nomment of the; 'other' sequenceswitcli wipers is with! out particularl effect at this tiine. Y

The operation of thel iirst selector Since, the first f ll. Fig.' l, in response tothe first series of code irn-V V'pulses Vinayfnow be briefly explained. Asf described inthe foregoing, the circuit oi the Y' vline relay 107 ofl selector E isl interrupted six-times at the armature 26 of'vrelay V27 annees of the trunk relay equipmentl), the`v circuit of the latter relay havin beenv interrupted six times at the inpusing Contact in the sendingswit'ch S.V As a result ofV the-six interruptions, the line relay 107 will cause six impulses of.` current toibe transmit.-

ted to the vertical' magnets (not shown.)A

which operate to raise the wipers 11,4, 115,

and 1210 step by' step' until they arrive at the sixth level of contacts.V At the end wellllznown huntingoperation takes place. When an idle trunk is reached, which it will' be assumed :isthe one indicated in the drawing, the testiwiper 115 fails to find ground on the test contact 111 and the rotary nim/"enrent-v of the switch yis arrested..

Y 75. otlv the vertical movement of the writelnA theY Switching relay 137 is now` energized'ilry the usiialvinianner, places ground on vthe test wiper' 115 in order to malte vthe selected trunk busyT and extends 'the trunk 'conductors 104 and 106 by way of armatures 135 Y and 13.6, wipersflI/l and 116,! bank contacts.y

and' 1391` Trunk conductors 137, *138,` and .1559, it may be stated,- extend to and termi.-v

113, to the trunk conductors .137 i l Y nate in the second selectinV E2, thecircuits i which are not shown, but Which-.is slicrvlfnV diagranziniatically in Fig. 6. On thefexte'H-- sion oft the trunk to the second selector:r E@ the line and release relays of this switch: are.

es i

energized in the usual manner, the 'switchV Y is prepared for itsV vertical operation', and a ground is placed upon the release trunk conductor 138'. v n f 'Y Y Y Y Retumingnow to the sending switch S,

when the: switch reaches its normal position! after the transmission of the frrstseriesj of code impulses, W1per513 will engage .an ungr'ound'ed contact and the circuit of relay 50 will be broken. 0n deenergizing,V rel-ay 506 again closesthe shunt aroundY the iin-v pulsing' contact 523 at armature 520,V and armature 5211 breaks the locking'l Circuit 'ofY the .st-op `relay `llielatter relay, deenergizing, again-closes. the circuit of the iinpul'sing relay 507 at armaturel 519 and L the transmission ofthesecond series of code impulses is started. As indicated in .the

drawing,- relays 505 and 506-are insideslowY acting-ni order" to introduce a. brief time int'erval between the transmission of successivek Y series of impulses, thus giving the selector switches `time for their automatic trunk huntingoperations.. The second 'series of' codeiinpulses is now transmitted/similar toV Y thel manner in which v`thefiirst series was? transmitted. Y When the circuit of the zirn pulsing-'relay 507 Vis completed at armatureV 1f 5.19 by the deenergization of stoprelay 505,

the said impulsing relay begins tofoperate 'Y intermittently under the control ofV the inter-f rupter I, and 'advances Vthe sending `switch step'bystep through the medium of the stepping-inagnet- 515. the stepof-the switch, relay 506 is energized, removes the shunt from the impulsing contact 523 at armature 520, prepares "a locking circuit for the stop relay at armature 521, and closes the circuit of the sequence switch magnet 402 at armature 522. On the second energization ot the impulsing rela-y 507 and on the succeeding energizations thereof, impulses will be transmitted overA the switch control circuit comprising conductors 173 and 33 in the manner described in the toregoing, and by the time the stop wiper 514 arrives at the No. 3 contact in its bank, a series of three impulses will have been trans` mitted. The No. B contact in the bank ot the stop wiper 514 is vnow grounded and, accordingly, the stop relay 505 is again energized, a locking circuit being established at armature 517 as before. Relay 505 also breaks the circuit of impulsing relayf507 at armature 519, closes the automatic rotary circuit at arlnature 51.0, and at armature 518 breaks the circuit ot the sequence switch magnet 402. On deenergizing, the sequence switch magnet advances the wipers to third position, whereupon ground vis removed from the No. 3 contact in the bank ot the stop wiper 514. y

Since there are only two series ot impulses in the oilice code, .the sequence switch S' must now be advanced automatically through its third and fourth positions `in order to prepare the. circuits tor the transmission of the thousands digit as soon as the sending switch S hasrestored to normal. This is accompiished automatically due to the tact that that terminal 331 is crossconnected to bus-bar Y at the I. D. F. instead oi to any ol the bus-bars which are associated with the bank of the sending switch. When the sequence switchv wiper 404arrives in third position, a circuit is completed for the` stepping magnet 402 which extends tromthe grounded conductor 400 by way of wiper 404 in third position, conductor 413, wiper 308 of register switch J and the contact engaged thereby, terminal 331, a jumper connecting this terminal with bus-bar Y, conductor 371, wiper 408 in third position, and through the interruptor contact and the winding of stepping magnetY 402 to battery. Upon the closure of .the foregoing circuit, the stepping magnet 402 energized momentarily and the vsequence switch wipersI are advanced to fourth position, whereupon a similar circuit is immediately completed which extends trom the grounded co1'iductor400 by way of Viper 404 in fourth position, conductor 414, wiper 309 of register switch J and the contactlengaged thereby, terminal 330, a jumper connecting this terminal with 1 bus-bar X, conductor 370 wiper 403 in fourth position, and through the interruptor contactand the winding of the stepping magnet 402 to battery. Upon the closure of the foregoing circuit, the stepping magnet `402 is energized momentarily and the sequence switch wipers are advanced to fifth or thousands position.

The two series of code impulses have now been transmitted and the director is in readiness to start the transmission of the impulses which correspond to the registered digits. In orderV that the progress of the call may be kept in. mind, it may be stated that in response to the second series of impulses, the wipers of the selector E2, Fig. 6, Vare raised to the third level, whereupon a trunk line is selected extending to the Sunnyside otiice, the trunk taken for use -being assumed. tobe t-he one which extends by way of the `repeater R to the selector vE3. The repeater- R is of the standard type and includes means such as a repeating coil by means ot which the trunk is divided into two inductively connected sections. It includes also a line relay operated over the incoming section to repeat impulses into the outgoing section, and a slow-acting release relay for grounding the extended release trunk conductor 138.

Then the sequence switch S is automatically advanced to the ifth or thousands position, wiper 404 `places ground on the wiper 244 of the thousands register M', and wiper 405 leaves the multip'led contacts which are connected with the grounded conductor 400 and engages its No. 5 contact to which is connected conductor 421 coming from the thousands register switch. Asa result ot the latter circuit change, when the sending switch S returns to normal after having transmitted the last series of code impulses, the transmission of the series of impulses which corresponds to the thousands digit ot the number is not started unless this digit has been registered, for unless the register switch Mf `has completed its operation, there will be no ground on conductor 421. In the present caselet it be assumed that the calling subscriber has completed the dialling 'ofthe thousands digit before the sending switchhas completed the transmission of the series oit cede impulses. klvhen the sending switch S arrives in normal positioniafter the transmission of the final series of code impulses, theideenergization of the stop relay 505 will be effective to again close the circuit of the impulsing relay 507. Since, the thou.- sands digit in the number is digit 2, the wiper 244 ofthe thousands lregister M is -now standing on the second contact in its bank, and since the wiper 244 is now grounded'by way ot' the wiper 404 of theV sequence switch S,-tliere vwill be ground yon the No. 2 contact in the bank of the stop wiper 514. lt follows that in the next operation of the sendingfswitch S, two interruptions will be produced in the impulsing circuit, similar to the manner .in Whh the several series of foo t cond (interruptions were produced.Y` These interruptmonstdr impulses, reldyedby relay 27, "are received the repeaterk R, Fig.y 6, and are repeated oi'er'the interofliee trunk line to' tli'efneoining selector E3 in the Sunnyside office, which operates to raise its wipers'fopposite the second level, whereupon ani Vidle Atrunl is Iselected extending to fourth 'selector which we will assume is' the selector E5. y

During the operation 'ol" the sending switch in transmitting vthe thousandsjdigit of the number, thestepping magnet 4:02 ol the se-` quence 'swvitehjS4 is venergized and deeneigized in therusuelvmenner and advancesthe seqii'ence'switeh wipers to the sixth vorhun- 'dredspositionm The inoyernenthiof sequence switchMwipe'r discom'ifects ground `from the wiper'244V of the', thousands register M tconnedtsff'rouiidto the wiper 245 of the hundreds i* ter by of conductor 416. .s'sufining'fthat calling subseriber h alredy 'dittlld the hundreds digit 3,' the ii'lctor '422 `will nowhsye a 4,gfro'und on it, Causingl the sending switch eto res'tartimrne.-

diatelywhen the lstoprely 5.05 falls bafcl.{. V Sinfc'e, 'the hundrieds `digit in the number v1s th'edi'git, tlierewill'now be "a ground on c the; No: 3 1c'oi'i'tct fin the bank of the stop i Y quen'ee 'switcl Y baille 5c nt''ets.

yif'i'p'er l5141i ottliefwiper -2l5 of the hiin'dr'eds register, and the sending switch Will'OIete to transmit a series of three impulses. vThese impulses, iteliyed by rel'ziy 27,*eie repeated by the-re'peter R, Fig. G, to the fourth select-or E in the 'Sunnyside olliife wliieli raises itstvipe'rs to the third level and selects en idle 'trunk ektending to a conn'eetor sfwitcligwliieh 'we "will assume to be therconnector H. f

.D'ui'inlj'y the 'operation oit tli'esending switch in ttrnsmtting theliundreds ,digit the sequence switch magnet numb ini the 4502 'isi'energyized end clenergiz'ed in Vthe* usual manner `in vorder to advance the se- 'ififvlpers to the seventh-orteils position! Assuming now tll'zit' the eztlli'ng subscriber hasec''nopletedV vthe 'diallingu of the te'isV digit,` conductor L123 will be grounded and wilpei" 2&6 will be stzfir'i'di'n'g; on LAthe No. l 'coi'itt'et in its bunk, thus extending a ground tot'l'le No. l Contact in tl'ie'lizinl 'of the sending switeli SL wA seriesbf'lour im- Yioulises is :iecidingly transmitted by the switeh,V thesevinipnlses, relayed by ifelay 27, 'are repeated bythe rep'eter R toV the Coni'iector H in the Sunnyside olli-ee,

when,faemrdingiy;mises ifs wipers in the,

'tlieiipu les Co responding tothe tens digit, Y

adv 'fe'sthe sequence' switeh 'wipers to the e l1 oifuvn'ijts position with the result that Wiper `104: places e ground on Wiper ino' relay i9 of tlieti'unk 247 of the'f'un'its register M4. I`Assu'min`g that 'the i'rial digit jbeen dialled 1by tlre calling subscriber, conductor 4124 will new be grounded; the 'sending switch S will be startedr ony its linal operation`` and `silice wiper 247 is vin'enggenoeiit 'witlithe No.v "5

,Contact in itsbank, a series of live impulses Vthe calling' subscriber hzisali'eady; coi'npleteld the dialling and. registration offtlie 'nektl succeeding digit.`V It will be understood-,ot 4Coursejwthat` in case there any on' the pztrt of the calling si'ibsci'iber, the send-A him und thatinsucha ease, `the rest v"",t'ig of the sending siifitchvwill lie4 postponedrun til another-digit has been registered. y vThe eneV izgitioii *and deenergizztion oil the sequence s'ivitch iniig'net 402 during the transmission of the llniil seiiestol"impulses czlfusesthe sequence sw'iteh wipers Vtolle ad-.f viucetl to the ninth` ior'swit: .ling position,l wliei"ou} on ,the folloiifingT eiieuit is' estilifV lished lior the j switching relay 512: lz'oin lground `byvwa'y ot sequence isxfi'iteh" wipe:-

IlOG ifn switchingl ,"position,V c( idl'lctioia i120,"

contacts Controlled' by nrmatuife), and4 the switching through operation. The relay should be so `adjusted that the springs represented by armature levers 15 and engage their working contacts betore any break contacts are operated, as a result of which the calling subscribers line Vwill be connected to the line relay ot' the repeater R in multiple with the relay 23 of trunk relay equipment D. The resistance 6 pre-- vents the short-circuiting of the subscribers line and the objectionable noise in the receiver which would occur il' short-circuiting should take place. Following the engagen ment of the above mentioned springs, the adjustment is such that armatures 17 and 21 will operate toremove relay 23 from the energize. At armature trunk, after which the complete operation of armatures 16 'and 22 will result in the removal of the resistance 6 from across theA trunk. The trunk is now clear of all bridges at the trunk relay equipment D. The operation ot' armature 20 results in the extension of the grounded release trunk conductor 51 to conductor 14.-.in order that the preceding switches may be maintained inlan operated position after the deenergization o'l" the line relay 150 of the director selecting line switch C".

`When the line relay 23 is disconnected from the truuk by the operation ot switching relay 19, it deenergizes and breaks the circuit ot the slow-acting line relay 150 `ot switch C3, which deenergizes in turn and opens the circuit of the switching relay 157. Relay 157, upon deenergizing,` dissociates the director selecting line switch C3 and the director, notwithstanding' the tact that the associated wipers are still standing on bank terminals 168 to 171, inclusive. rlhe breaking of the contact at armature 159 causes the deencrgization oi" relay L17 of the relay trunk eqiiipn'ient D, this is Without ell'ect, however, as the bridge has already been removed from the trunk by the operation'of relay 19. A further result of the deenergization of relay 157 to disconnect ground from conductor 173 and troni holding conductor 172, as a result oit which relays 510 andk 51.1 in the director will dceiiergize. On deenergizing, relay 511 connects ground tothe upperliank olI the sequence switch at its armatures 533 in order to advance the sequence switch wipers to their normal position. .At the saine time, at the upper armature 553V the locking circuit ol switching relay 512 is broken and this relay is permitted to de- 532, relay 511 connects wiper 513 of the sending switch S with the `stepping magnet 515 through its interruptor contact. This operation, however, is of no particular importance, ordinarily, owing to thetact that the sendingV switch is restored automatically by the completion of the same circuit at armature 516 of the stop relay. Relay 510, on deeiiergizing, connects Vrem ain grounded.

ground to release conductor 204 at armature 530', thus completing parallel energizing circuits for the release magnet 211 of' the master digit controller M, the release magnet 805 ofthe register switch J, and the release magnets 220, 221, 222, and 223 of registers M to Mt, inclusive. rlhe several switches mentioned are accordingly restored to normal position in the well-known manner, each switch opening the circuit of 'its associated release magnet at its oil-normal springs as soon as it is fully restored. The low resistance relay 508 is included in series with conductor Q04, and, on`enei", 0izing,` disconnects the holding conductor 172 from the local holding conductor 203 and connects the forinerconductor to ground. This operation places aground on the test Contact 171 and its multiples in the banks ot the direc* tor selecting line switches such as the switch C, and prevents seizure of the director while the register switches thereof are returning to normal position. Relay 510, on deenergizing, also connects up the high resi tance relay 509, the upper winding which is connected to wiper 513 ot the sending switch while the lower winding is con nectcd to wiper 103 o1 thesequence switch. l/Vhen relay 510 falls back, therefore, relay 509 will be energized, since the sequence switch S and possibly also the sending switch S are out of normal position, and at armature 527 will prepare a ground for the holding conductor 172. It follows that when the relay 508 fallsbacli on the complete restoration of all the register switches, if the sending and sequence switches are not yet fully restored, the conductor 172will It may be stated that ordinarily the sending and sequence switches will arrive at normal position at approxi mately the same time as the register switches are restored, and the relay 509 is provided. chiefly to guard against some defect in these switches by which they might be prevented troinrestoring i at all. It' one of these switches should get out oit adjustment, for instance, and fail to restore, it would render the dii'ect-or completely inoperative, but in such a case relay V509 would be maintained energized in order to keepthe trunk extending to the director in busy condition. Vhen either relay 508 `or 509 is energizcd,a ground is placed on conductor 198 which may be used to operate some kind of alarm to signal a switchboard attendant. Y

The contact springs represented by armature 532 and its resting contact are added to relay 511 in order to insure that the sending switch S will be advanced to normal position in case the'callingsubscriber should hang up his receiver while the sending switch is operating, and betere the stop relay 505 is energized. For example, if the calling subscriber should hang up while the director lill is in use, the linev relay 23 of the trunlrrelay equipment D will fall -rback and cause thedissociation of the 'director selecting lineY switch C3 and the director, whereupon all the register switches in the director will be restored vto normal. It the circuit of the `irnpulsing relay 507 should be broken by the removal offground from a conductor such as L100er 4121 while the said impulsing relay is operating to transmit impulses before VtheV stop relay 505 is energized, the movement or the `sending switch would be stopped and it would remain in an oit-normal position.

' However, the provision ofthe Contact springs mentioned preventssuch an occurrence, for

whenever the director is released, relay 511 is deenergized andv the said contact springs are effective to connect the wiper 513 to the stepping magnet 515, with the result that the sending switch 'S is always advanced to normalaposition no matter whetherV the 'calling subscriber Ihangs up prematurely or not.

As described in the foregoing, the connection is switched through and the director is released as soon as theiinal series of impulses hasbeentransniitted. The director is thus used only during the actual setting up ot the Y connection andisrendered,accessible to other the called subscriber answers,'thecalling Vcalled lparties will converse as subscribers as soon as the connection is conipleted. After the connection has been switched through, it vis the saine in all essenvtial particulars -as any ordinary automatic connection, such vas foundv in ordinary automatic telephone systems which do not employ directors and is controlled by the calling subscriber in the usual' way.y lVlien and will Vreplace their receivers` wlicn the conversation-is Vfinished.` The release ofthe connection controlled by the callingsul'iscribeif.v .Vihcn thereceiveris replaced the calling station, the line and release relays Y ot therepeater R are deenergized, with the `up and, releasing a typical connection, will be desirableynow to consider the special'- *caserepresented by a connection `to a called substation located within the same oiiice las 'the callingsubstation. Forthis purpose, it will be assumed thatthe subscriber at station V.eL-'desires to entend a connectionto thesubber is BRyant 2375. Topioceed with thees-4r tablishment oi the connection, whenjthej cal-1K;V ing subscriber vremoves his receiver, his line iied, p and is exten-ded topa iirst selectorv trunk aspreviously pointed out, 'and lit Willbe assumed.

that the rst selector trunk illustratedin F ig. 1 is the one taken for use, it being also assunied that the director taken for use is the one illustrated in the drawings. calling subscriber will nowL dialjthe `letters B and R of the called number, as `al resuli of which the register equipment in the director operates to register the Yabove `letters in pre-` cisely the same manner as ,was described in the preceding easel The register switchv J, Fig, 4, iscontrolledby the line relay 23 of the `trunk relay equipment lD and receives two lseries of impulses, one comprising three impulses andthe other comprising two impulses, in accordance with which its wipers raised three steps lto the third level, and' are then rotated two steps into engagei ment with the second set of contacts. At

the. end of the rotary movement of switch J, relays 207 and^208, Fig. 2,- deenergize an' instant apart and thus cooperate in jtransniitting an impulse Vofv current to the stepping magnet 212 of th'e master digit controller M, the wipersof which'accord-f inglyadvance 'from second to .third.position.V As a result ot theabove action, agroundis ilaced'on starting conductorv 400 by wiper 219, and a circuity maybe traced from the ygrounded conductor 400 by way offwiper 4.04, conductor 411, wiper 306,"of register switch J and the contact now'engaged thereby, terminal. 3111 on the lett-hand side'oitlie I. D. F.a Juniper` connecting this terminal with bus-barSV, and 'thence by way of conductor '5G/l, .through the upper ni'indiiig of relay 512 to battery On energizing, 4relay 512'estab'lishcs a lookin` Y l winding at armature 539.;

When the relay 512 becomes energized, ,a number ot circuit cl'iari-csare brought about, for convenience of explanationthe circuit established at armature 537 Wi'll'lirstlbe considercd.

g circuit 'for itsv lower' In this connection, circuit is` traceable from "grounded .conductor VV564,

working 'contact and armature 537, conductor 175, banlrcontactlGS, wiper 164W`orling? contact and armature ,158, conductor 52,

armature 63 and resting contact, restingV contact and armatureqGO, through stepping l magnet 68 tobattery. ,The stepping magnet GSwil'l energize 'over the above traced cirf cuit, but will not cause a movement of kthe wipers 75, 7 G, and 77. The stepping magnet, uponfenergizing, opens the circuit ot switchingrelay `57 at arniatureiv67, whereupon the switching relayv deenerg-izesfand again connects yfthe slow-acting line relay v61 land ground to the ,trunkconductors Oiand 5??, at Y armatures 5 4 and 497" -iespectively.v Line relay 61 innnecliately-jenergizjes and )laces ground uponthe release trunkpconfv sector 51- by .Way-.0f .armatures 15.9,-ana46. 1 A further .resultfof 4'the denengizatvignl Qf 'Y relay 57 is the closing of a circuit traceable from grounded conductor 52, resting contact and armature 58, rest-ing Contact and armature65, winding of switching relay 62 to battery. Relay 62, upon energizing, :forms a locking circuit for itselt by way ot armatures 65, 60, and 59, breaks its initial energizing circuit at the same time, and disconnects the trunk conductors 49, 48, and 47 from the primary wipers 75, 76, and 77, and connects them to the secondary wipers 117, 118, and 119, respectively, at armatures 69, 70, and 71., The line relay 61, upon energizing, removes the grounded conductor 52 from the stepping magnet 68, thereby causing it to advance all the wipers one step, the wipers 117 118, and 119 now engaging bank contacts 120, 121, and 122 respectively. The line relay 61 also closes a circuit for the switching relay 57 in series with the stepping magnet 68 at armatures 60 and 59, and at armatures 64 connects the test wiper 118 to the above circuit at a point between the winding of the switching relay and the winding ot' the steppinginagnet. If the local third selector trunk with which the.

secondary wipers 117, 118, and 119 of the switch C* are now associated is busy, there will be a ground on the test contact with which the test wiper 118 is in engagement, the switching relay57 will be short-circuited, and the stepping magnet 68 will be operated to advance' the switch wipers into engagementwith the next trunk line. It thenext trunk line is busy, thesame operation will be repeated and the stepping magnet 68 will continue to operate in the manner local third selector E is idle, then switching relay 57 will be immediately operated when fii its circuit is completed by the said line relay, as pointed out under the second alternative above. Upon attracting its armature 56, relay 57 connects ground to lthe test wiper 118, and thus makes the trunk line extendingv to selector EG busy. In addition to the foregoing, at armatures 54, 55, and 49 conductors 50, 51, and 53 are extended kby way of armatures 69, 70, and 71 to wipers 117,

118, and 119, respectively, and thence by way of hanlc contacts 120, 121, and 122 to conductors 123, 124, and 125, respectively, which extendV to selectorEi. Zhen the trunk is extended to the line relay 126 of selector E", the said relay is energized and in turny closes the circuit of the release relay 127. Upon energizing, relay 127 connects ground to the release trunk conductor 124 at armature 128, thereby closing a holding circuit for the switching line switch Gt, which extends by way et the said conductor 124, test contact 121, wiper 118, armature 70 and its working contact, armature 56 and its working contact, winding of the switching ralay 57, and the winding of the stepping4 magnet 68 to battery. A branch of the above circuit is traceable from armature 56 and its working contact, working contact and armature 65, winding oi' relay 62 to battery. This holding circuit is established before the slowacting line relay 61 has had time to deenergize, and is elilective to hold the line switch C* in an operated position lthroughout the connection. Relay 61, upon deenergizing, doesnot again close the circuit of the stepping magnet 68 because ot' the open circuit Vat armature 66.

A further result of the energization of the switching rela-y is the opening of the circuit of the line relay 107 of the tirst selector E', with the vresult that this switch again becomes available :tor use in setting up other connections.

Returning to a further consideration ot the switching relay 512; it may be said that the switching relay 19 in the trunk relay equipment D is operated as previously eX- plained, the calling line switched through,

and the director released in the usual manner. In actual practice, it is very likely that the switching through by relay 19 will take place before the trunk is extended to an idle third selectoigthis introduces `no complications, however, as the switch C4 maintains a. ground upon the release trunk conductor 51 until such time as a holding ground is returned from the first selector.

Since the connection has been switched through, it is now the same in all essential ijfartirailars as anyv ordinary auton'latic connection, sucl as is iiound in ordinary auto-- matic telephone systei'ns which do not employ directors, and is controlled by the call-- ing subscriber in the usual way. Assuming that the calling subscriber now dials the Athousands digit 2; two interruptions will be produced, inl the line circuit as a result of which the local third selector E6 will operate to raise its wipers opposite the second level, whereupon an idle trunk is selected extending to a fourth selector which we will assume is the selector E. Assuming that the callingysubscriber now dials the hundreds digit 3; three interruptions `will be produced in the line circuit as a result' ot which the fourth selector E7 will operate to raise its wipers opposite the third level, whereupon an idle trunk is selected extendfir 10er ofte @da plurality IQf @they .Orages the fQr.A werden@therewith meses L fer asserting --erlfflle drretfrrI Wltlr, e Cellule '111146, rrd

ing tov-a5 eenrreeter erhielt We will assume .is

the, connector II?. Assiirning that the calllrg subscriberfnew. dials the tens digit 7..;

SeYentetrLrpt-pns willi be Produced in the.

line crleuit as.V a` resultof*i 'wliicliftlie connector fHxwJll operate to raiselts vWipers oppositetheseyentli level. Aslsuniingtliatthe f rllrle', subscrberlrrrewdials. the uiits digit 5 dre interruptions will; be; produced. in. the lnextrutasetresultof:Whichtheeonrreeter H12; WillT operate to retate tswpers into. conf metier with?` the lite extending to vthe. Sta,- tionl Uponwthenconipletion of the con,- reQiQnf-tQ-.tbe .Called line, a Signalling @ir-f Cuitis esteblhsd int the Connector 1n .the ilsuffrllrlelllrer.and;the 'bell at the Called station is opcrated,to notify tlie` siilescriber Y thath 4is Wanted?. r

sjdeSQribed ,inf the .fQregQirra the @0er rreetfions Switheltlirorreh re @leealtleirfl Sel d ,tliedirector releasedas soon, as

cr1t1cal'cliaractzer is dial-led.l which de?v 'die @eine..5rrbsefion'. the une @des off the; connector H?-Y are.,A deenergi'zed,

with; thatt 'the holding circuit ,for

the, autornatic switches is'j broken, Itl follows tha described, Wliat: is 'considered ,toI ybe newgand it lis desired. to l1a51eprotec i dliy 'Letterslatent Will be pointedoul Indre specifically in` the` appended. claims.'

1, xnlltiolflce. telephone system, a local office anda plurality of other oliices, directors in fthe.local`- otlilce fon register-.zing "i'grits infrallerl;teleeheee. numbers and .control,ling, r autornaticv switches in merrlsrfetiferr. caserme/Called? line-,s in Qelpreeor.rrereedretely-rfrsrorrngthe dire ori Ato,common Y use jas soon as suliiclent 'drets-"ere l registered? te. determine the. destidirectersT iltthe. leert slice, for: registering the. .d-gite rr Calledtelepheneinumberwnd "forf cxrciutrollir),g,v antoniatic,V switches. kin awerdrrrrrethererrrth, vruterrrrtlc- Semelle-5.111

the, saidA other Noflices `cont-rolled from Said 100M @T106 only vthrough the. rrnediurrlv 0f' said directors, and. automatic switches Vin' said local oice vdirectivelyl controlled dif( rectly lojy1 calling'` subscribers therein Without 1 the intervention of thedirector-s.

3. In al nnilti-oflicetelephone system,a1i f f ol'lice selector, a local selector, a divided trunk having two branchesl extending.y to said selectors,` respectlvely,

really cenrretert means for: connecting 'e calling linewitlisaid trunk line, a directorandy nieans for associating itwith said trunk line responsive to the call, said; dire'c-v tor comprising registering devices `for recording vthe digits inthe called number, en@ means responsive. t0 the registration-0f the olilice digits in the called ,-nnnilier. for @erecting the Meel branch and :ferr discenr Destins the other bralrelrofsed trunk-:line in case suclidigits determine Vthat thecalled partyisinthe.localoflice. c

l. In al multifoilice .telephone system,

switch having two seatsi ot Wipers for con-v the. breech extending tosald oiiice selector being ,nerf` f necting withe said office andl local selectors, i

respectively-*a trunk line-terminating, in said .hunting switch, means for connecting a` calling line With',saidtrunk-line, a directoi; `means for associating it with said trunk line responsive to the call, saididirector comprisingl registers for.y recording the r digits in the callednuniber, means tenantematically operating; said hunting, switchlto. extend` said trunk lineito an*v idle oilce .selec-l tor, an d meansl responsiveI to the vregistration Of the @Hice digits in. the elledfnrrmberfor causingsaid hunting switch. to disconnect from the rselectedzA olic'e` Selector and select Aan idle local selector in case SuChfdigits determine that the calledfparty is inthe local olfice. o l

5. In a telephone system, a trunk line terlninatingin an automatic switch, means a4 calling line to, said trunk line, a director and means for 'connecting it to said trunk linea'esponsive. to` the'call, said director including registering mecha- .nisni rset- Vby the subscriber-on Asaid line,

means in the director. for Operating.l said switch, and means in said director effective contingent. on a particularl setting offsaid registering mechanism, Yfor releasing; said switch Wliile maintaining the n, callingmline and trunk line connected. 6.; In., a, telephone, system, trunk liney f terminating 11,1. en entfernen@.swiittl,v means lfor Connecting a, Calling-line t0 Sadtrunk line,v a. direct/er rrrd means. lvforicorrrlectngdt to Said 'trunk line 'responsive Sto; thecall,

n Said director including registering mechenisnll set by the suloschrilier-on said., line, second and; tliird trunk lines-accessible to Srdswith, means for Operating Said swth'

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