US1691269A - Wire chief's test circuits for telephone systems - Google Patents

Description

Nov. 13, 1928. 1,691,269

- '1'. F. CROCKER WIRE CHIEFS TEST CIRCUITS FOR TELEPHONE SYSTEMS Filed Dec. 9, Sheets-Sheet l -In1 r.en or Thames Fljrmckar Ndv. 13, 1928.

T. F. CROCKER WIRE CHIEFS TEST CIRCUITS FOR HE'ILEPHONE SYSTEMS Filed Dec. 9, 1925 4 Sheets-Sheet 2 Iuuen :1: Thames Fi rmnksr Nov. 13, 1928. 1,691,269

T. F. CROCKER WIRE CHIEFS TEST CIRCUITS FOR TELEPHONE SYSTEMS Filed Dec. 9, 1925 4 Sheets-Sheet 3 Nov. 13, 1928. 1,691,269

T. F. CROCKER WIRE CHIEFS TEST CIRCUITS FOR TELEPHONE SYSTEMS Filed Dec. 9, 1925 4 Sheets-Sheet 4 --Inuan or Thames Ffrucksr ing circuits especially adapted for use in Patented Nov. 13,1928.

THOMAS F. cnocnnit; or CHiCAGO, ILLI noIs, Assienoit, BY MEsnn nssrenmnnrsfro AUTOMATIC nrnornrc nc, or cnrcaeoimmors, A CORPORATION or DELA- wrnncninr s TEST cinoui rs iron TELEPHONE SYSTEMS." I

-' Application filed Decem b'er 9,1925.- SeriaI N o. 74,231;

This invention relates in general to wire ch efs test circuits for telephone systems, I but isconcerned more particularly with testautomatic telephone systems. Theobject of this invention, comprehensively stated, is the provision of revised and mproved testing circuits for the wire cliiefs position; winch facilitate and oromotespeed and accuracy in the performance of the various tests to be made by'the wire chief. I 3 j The performance of the regular'routine tests of the subscrb'ers lines is one of the principal duties of the wire chiefs In the performance or" these tests, the operation of keys is a considerable part of thelabor'that must be performed by the wire chief in making the various tests or in establishing testing connections to subscribers lines. To

establish a connection with a suhsc'ribers.

line or with a secondsnbscribens line after the completion o'f the testing oi the first sub-- scribers l ne, it has been necessary tor the wire chief to operate Et-(llttll ngihey bei'ore the necessary digits toesta'blish the'firstor the seccndconncction could be dialled A0 combine to special feat-ureo't this connec tion, the number of key operations that inustf be performed to make the required tests on lines has been reduced by eliminating the necessi by" of operating a dialliim key when a new connection is desired. In this new test cord," the preparation oi the c1 "cults tor "dialliii 'is automat cally performed by relay operations, which are initiated by the move:

ment of the calling cleyice t'rom its normal position. 7 v

V Another featureofthis'new testing circuit relates to a busy tone and-the superv sion which is given tothe wire chief when he has" may be extended by thefwirechief to another 95 established a connection with a busy? sub scribers line. The-circuits areso designed:

that the busy tone is heard by'the wire chief and asupervisory lamp is lighted when a" supervisory lamp is extinguished and the described with the aid busy tone is removed when the listening key in the test cord is throwm ma'lrmqiupossible for the wire chief to then'listim to the conversation of. the busy subscribers and verify the busy condition of the 11116.-

by a connection having been established either with a subscribers substation or with a trouble man on asubscribeflsline will not be released y the removal of the-test cord c plug from the outgo'ng trunlrjack, super-- VlSlOll being had by means of a superyisoiyfl lamp individual to the outgoingtrunkz With such an arrangement, the wire chief mayi'set up connections with several troublekmen or subscribers lines, each lover 'a diii erent out-1i go ng trunk from the wire chiefs position, and may then perform the requiredtests on any line as is desired or requested by trouble meniwho may bemaking adjustments out on a the lines; The connection of thetest cord" may be shifted from one established connec' tion to another by merely transferring the test plugfrom onetrunkjack to the'other' trunk jack. 4 1 i- "a" Another minor feature of this invention relates to the dual function of a certa n relay in a trunk circuit of the trunkiter nin'ating': at the wire chiefs position for general in-: coming and outgoing service forthe wirev chief. Thisirelay operates in series with a condenserres'ponsive to ringing current to signalth'e wire chief on incoming calls and is included i'n the holding bridge independent of these condensers onoutgoing calls.

. single ending cord circuit especially designed 1 y i for use in conjunction w th the telephone set ofjthe wire chiefs. testinghequipmenh by; which an incoming call from one subscriber desired subscribers line.v

i i v. I: These various features and other features, not spec allymentioned, will be described more in detail in the following specification in'connectionwith the explanation of theoperation ofthe various c'ircuitswhich areofthe accompanying drawings. i a

Referring now to the drawings comprise ing Figs; 17, inclusive, there is shown by means of theusual oircu it'diagramathe testins; equipment, the trunk ClI'Cu' tSQOf the 'various kinds of trunks terminating at the.

the transmitter T, receiver R, calling device S, and certain relays having special fun c-.

isuchas I scr1bers7 hnesflztor general routine testing are 424, terminating in the jack; J Fig. 4, is;

wire chiefs position, and sufli'cient auxiliary" apparatus that is brought into play in making various tests to clearly describe the features and utility of the lIlVQIlLlQIl. The drawingsare to. be placed with their correspondingvlines in alignment, in the order shown in the diagram, Fig. 7. In Fig; 1, are shown the test circuits proper and the necessary auxiliary apparatus associated therewith. In Figs. 2, 4, and?) are shown three trunks with their, individual trunk circuits terminating at the wire ch'iefs position. Fig.

3 :shows 2 the circuits of three automatic switches, known, respect1v ely,-. as a test dis- ,tributor, a test-connector, and airotary line switch, which isindivid-ual to the subscri bers line to the automatic substation A. In

individual primary line switch. I Individual,

Fig. 6 is shown the special singleending cord to be used in connection with the wire chiefs telephone set shown in "1. Atrunkterminating' at'the wire chlefs. position with which the single ending cordSC is; to be used, is also. shown in Fig. 6. I j

The wire chiefs testing equipment proper consists of a telephone set TS and the test cord C, Fig. l. The telephone set includes tions that will be described subsequently. Thetest cord is equipped with the usual keys which, in being operated,lperform functions or prepare the circuitsfor making the var- I ious tests, as 1s known'toitho'se skllled 1n the; art. Several special relay's asociat'ed with is oneof; a group of trunks terminating at the wire chiefsposition, each of which is permanently connectedv to a tQStdlSlZllbUtOI,

: TD, Fig. 3'. Connections to the subest'ablished overthis trunk or a similar The trunk'compri'sing conductors 423 and permanently connected to an individual line switch,iqwhich maybe similar: to the line switch,LS, shown ln' Fig. This trunk s also accessible 1n the connector bank contacts 433 i and 434" or multiples. thereof. This trunk is individual to the wire-chiefsposi-j tionand is used for general incoming or outgoing service to or. from the wire chief.

'The'trunk comprism'g conductors. 523525,

inclusive, terminating at the wire chiefsf position inthe jack J ,.Fig. 5,.is one of several trunk lines accesible in a certain level of bank contacts of a certain group of selectors. The code number for establishing a connection over this trunk isnot listed in the general'directory, this trunk being reserved for use by trouble men: who may be'out inthe field testing the subscribers lines andwho wish to establish communication with the type, having ten horizontal rowsor levels of bank contacts, and is responsiveto two digits remove its wlpers 1n averticaland in a rotary mot1on. The test connectorTC' also is mechanically of a'St'rowger step-by-st-ep vertical and rotary type, functioningin response to twodigitsdialled by the wire chief to raise its wipers andthen rotate them into engagement with the corresponding bank contacts atwhich a subscribers line such as the line comprising conductors 391 and 392 terminates.

Each subscribers line terminates in an to the subscribers line'to substation A is the line switch LS which is of the rotary type whose wipers have no normal position and having, the usual talking instrumentalitics and the calling device S. c

The single ending cord SC, shown in'Fig. 6. is permanently associated with the wire chiefs telephone set'TS by the conductors 21"'24,inclusive, 2 6 and 27. Thiscord terminates at one end in the answering plug P and is permanently connected to an individual line switchwhich also may be of the rotary type similar to the line switch LS shown in Fig. 3. This cord is provided with a dialling key and a talking key and special relays,

having functions that will be vdescribed later.

The trunk, comprising conductors 671-67 3,

inclusive, and terminating at the wire chiefs position in-the ack J, is one of a group of similar, trunks accessible in the bank contacts ofa certain group. of selectors. The code number for establishing a connection to the wire chief over this trunk is listed in the general di ectory and maybe used by the local subscriber'for establishing connections to the wire chiefs position for such special" service, as may be assigned.

A detailed description of the trunking between the test "switches is thought to be unnecessary. From the foregoing, however, it is evident that a 10,000 line capacity sys tem requiring the dialling of four'digits to establish, a connection has been assumed.

. There .will .be 100 *groups of connector switches, and as a tester connector is provided in each of these groups, there will be 100 test connectors. Furthermore, since the test distributors have 100 contact sets and are" directively controlled in both their vertical and rotary movements, all of these test 7 connectors may be reached by way of the. test distributors without any intervening switches.

ithithisgeneral description "of the telephone system which hasbeen chosen for olescribing the utility and the oper'ation'of the various features of the invention,- the opera" tion of the circuits may now be explained in detail. For thispurpose, it will first assumed that the Wire chief wishes to establish a connection With the line of substation A for the purpose ofperforniing the usual routine tests on this line. The Wire chief first inserts the plug P of the test cord G into the jack of a trunk to an idle test distributor. For the sake'ofsimplicity, asinigle position Wire chiefs test desk hasbeen assumed and it has also been assumcdthat the distributors accessible at the wire chiefs desk are individual thereto. r hen the plug P isinserted into the jack J assuming the trunk terminating in this 1 ack is idle and isthe one selected for use bythe wire chief, contacts 218 are closed, thereby closing a circuit which may be traced from ground'hy Way of the closed springs 218, through the winding of relay through the resistance 21'? to battery. Rei lay operates andprepares a point in the operating circuit for operating succeeding switches at armature 214, and prepares holding circuit for itself WillCl'l includes the Winding-of relay 203 at armature 215. Re lay'203 is not operated at this time by reason of the ground on both ends of its irinding. Another'result of the insertion of plug P into ack J2,1S the SttbllSll1nGnhOf a circuit which may be traced from ground by Way of armature 38 and the restingcontact, resistance 41 closed contactsf55, closed contacts 57, closed contacts ,52," sleeve oi plug P, sleeve ofja'ckd through the Wind ing of relay 201, through the upper Windlng of relay 202 to battery. Due to there sistance 41, iiecurrenuflow at this time through re1ay202 is insuflicient to cause its operation. Relay 201 is energized, however and by the operation of its- arniatures 206 and 208, the tip and ring conductors connectedto the jack Ji are disconnected from the operating circuit at the normally closed springs controlled. by these arinatures, and are connected to the testingconductors 223 and 224- the Working contacts" of these armatures; respectively. A "point in the supervisory circuit of the lamp L is also opened at the resting contact of armature 206. At armature 207' and its Workingcontact. a bridgeis placed across the operating conductors 221 and 222'. by closed for the linev relays 302 and 303 of the test distributorTD which may be traced from ground through the'winding of the line relay 802, normally controlled by armature 315, conductor 221,

armature 20? and its Working coutectynor inallycl osed springs controlled by Zl'llittll' 210, working contact andarn1ature214, con- 1 establishing a circuit springs, through the winding oi the slow-s acting relay 4- to battery. i l'lelay loperates" and closes a circuit for relay 32in the test conductor, thereby openin relay 201, and silt the Work-in arinz-iture a circuit s clos h g its ,iu' natures ductor222, normally closedsprings controlled by armature 316, through the Winding of the line relayBOS to battery. Relay 305 operatesand closes a circuit for the release relay 30a at-arin-rture 819, and prepares the impulse repeating circuit, to be described later at arm ure e20; Relay 302 operates and closesan alternate circuitfor The therelease" relay 3O 1 a't armature 318. operation of armature 317 has no utility at this time Release relay 30-1- operates and 1 prepares the'circuit for theoperating],

magnets 01 the switch at its working contact, and gizing circuits for relays 2307 described 1 later, Working contact. I i i i The foregoingoperations all take place responsive to the insertion oi the plug; Pf into the jack 3 The circuits are now pre pared to receive the impulses produced by the IDOVGIHGHtOf the calling. device S, when the Wire chief dials the proper' digits.

arnia-turc 321 and andE-OS), to be When the calling device S is moved ironi its normal position by the setting operation or the dial, springs 19 are closed, thereby irom ground at these cord circuit from ground by "Way offthe Working cont ct at armature 1 1 through the Winding oi slow acting relay 32 to battery. The operations of arm tureslg' and'lo performsno function at this time provided the talking key'in" the cord circuit C is not Relay 32 op'{- circuit by bridging the calling deviceia and the polarand ring c0115 'urcs 37 and 39. ,Atthe resting contact oi arnntture 38,

operated, as will be assumed crates and" prepares a (118i ized relay across the tip ductors ofthe test corc at arn i ground potential is removed our the sic-eye -ontaetof I the slow acting relay 31, the; i

contactsiiS. Relay 31 operates resting contacts of ar-matures disconnects the springs .and' at the 35 and 38 of the reversing'key,

.ning apand'ring conductors oi' 'the i and the Working contacts of ti aiidSi), sub

7 1' er mature .34'has no utility. The purpose the resistance 42 is to prevent thelighting or the lamp L 'at this time; I

As soon as the ci" opened, this relay de the purpose of'whi'ch Will he ex and by 1 206 and 208 the t and r ng conductors of the} lacs? are a a connected to the operatingconductors 221 prepares the enera at armature and its t l the circuit for t inclu-din in the tip contacts 339. and operates its armature .323 The next and 222, respectively. The release ot'arinature 207 opens the initial bridge across the operating conductors 221 and 222, so that thecircuit for the line relays 302 and303 now includes normall closed contacts controlled by armatures 200 and 208, tip and ring oi jack J tip and ring or plug P, contacts 51 and 52, arinatures 37 and 39,-and their workingcontacts in multiple with armatures 35and 36. andtheir working contacts, respectively, polarized relay 5 shuntedby the resistance 18, and the calling device S. The, direction. of the current flow in the polarized relay 5 at this time, however, is in such a direction as not to cause its operation.

The relay operations described in the im-.

mediate foregoing paragraphs talze' place responsive to the setting operation of the calling device. After the setting operation, the calling device is allowedto return to, normal, thereby producing circuit llllZGll'tlP-' tions or impulses, the number of such 1111* pulses corresponding to the digit at which the calling device was set, thus causing corresponding'number ot' d energizations of the relays 302 and 303 in the test distributor. The first time the line relay 303 deenergize, a circuit is closed which may be traced from groundat the armature 319 and its resting contact, armature 321 and its working contact, normally closed springs 339 through the winding of the slow acting series relay 305, through the Winding of the vertical magnet 311. to battery. Vertical magnet 311 operates and raises the wipers 3 1L346, inclusive, opposite the first level of bankcontact-s, at the same time permitting the closure of the on normal contacts 339, and' opening the Series relay 305 energizes time the line relay 303 deenergize's, impulses of current are received by the vert cal magnet over a circuit similar to the initial cir-' cuit,'except thatit now includes closed con.-

tacts 339 and armature 323 and itsworking contact, excluding contacts 339. Due. to the slow acting characteristic of seriesv relay 305, this relay remains operated during the sending of the remaining impulses of thisdigit. Each time the vertical magnet re ceives an impulse. it operates to raise the switch w pers opposite the next level. In;

this manner, the wipers 3e1*346 are ele- --vated step by step until they stand'o oposite 1' .the level of bank contacts corresponding to the first digit dialled by the wireschiel'. At tlietermination of the impulses oi the first digit, relay 305 deenergizes and prepares a circuit for the rotary magnet312at armature '323 and its resting contact.

hen the calling device returns to normal after the dialling of the first digit, springs 19 are again opened, thereby opening the circuit of the slow acting relay Relay deenergizes and by releasing its armature 14 opens the-- circuit for the slow acting relay 32. vEelay32 (lGGDGIglZGS By releasing its armatures' 37 and 39, thepoints at which thecalling device was initially brid ed across the tiaand rino' conductors I k t) 1 o oi'the test cord are opened.

bridge consisting otthe calling device and the relay 5 and resistance :18 in parallel is. still maintained across" the tip and ring conductor at. ai'inatures 35 and 36. By the release of armature38, ground'is replaced on the sleeve conductor at'the resting contact, 'and the-circuit of the slow actin relay 31 is opened at the working Contact of this armature. Relay 201 is energized and again places the holding bridge across the operat ing conductors 221 and222 at armature 207,

and again connects the tip and ring of acl-:.

2 tothe test conductors 223 and 22lat armatures 200 and 208, respectively.

Shortly after the deenergization oi' wrelay- 32, which opens the circuit of the slow ac s ing relay 31, relay 31. deenergizos and opens the bridge including. the calling device-S across the tip and ring conductors of the test cordC at armatures 35- and 36. By

However, thereason of the slow acting characteristic otf relay'31, this bridge is notopened, however, until afteri'elay 201 has operated to replace the holding bridge across the operating conductor at armature 207, and maintain the.

om ground by "way of armature 319 and its resting con tact, armature 321 and its working contact, springs 339, armatures 323i and its resting contact, resting contact and armature 331, armature 334 audits resting contact, through the winding of the rotary magnet to battery. In response to the impulses of current transmitted to the rotary magnet 312,

switch Wipers3l-1-36, inclusive, arei'otated step by step into engagement with the set of banlrcontacts corresponding to the digit dialled. The slowacting relay 306 energizes in multiple with the rotary magnet 312 and is 'niaintained ener ized due, to the slow acting characteristics throughout 'the entire rotary vmovement. In operating, relay 306 closes a circuit for the slow actingrelay 30!, which may be traced from ground by way of the working contact and armature" 322, resting contact and armature 333, armature 325 andlts worlnng'contact, through the @windin of rela 307 to batter Rela c Y y y 2t over a cir- 1,691,269 307 operates and prepares the initial energizized relay 5, causing this relay to operate. ing' circuit for-the switching relay 309 at As aresult oftheoperation'ofirelayr5,;;the armature 328, and disconnects the: heavy busy tone circuit-isclosedat armature lfi and i, i' testing conductors 223 -a11d= 224 from the' the'iWorking contact Whichniay be traced Wipers 341 and 346 at armat-ures 326 an'difrom the busyhmachine B,working contact 330, respectively. Armature 32 1 of'relay' and armature 16 through the. uppermost I 306 and armature 327 0i3relay 307 have Windingofthe induction coil M, throughgl'x, no utility at present Whenrthe dial S- the receiver R, resting contact and, armaagain returns to normalfat thetermination ture '15; it being. remembered the relayg of the sending of the impulses of thesecdeenergizes when the calling;devicereturns 0nd digit, the OPQIiLtlQDS"OOIICGTlTlDg relay to normal,- resting contactuandarmature 12, -15

4, relay 32, relay 31, and-relay 201 take place condenser 29, armature Qand thelresting con-' i as described hereinbefore, and theline re-wtactvto groundj 4 At m-imauetlt :and -.the

lays 302 and 303' are againmaintained en- Working contactaholdingcircuit is closedergized. c 'Ai' tenan ntervalyrela-y 306 defor relayi 32 which includes contacts 59, 130

energizes andreleases its armatures. vItmay working contact and armature Mpandzre-j v be assumed that other operatorshave access sistance 42. The deenergization 0151613). 32,-;

'to the test connectors byway of test diswhich wouldordinarily takelplacepa ashort f tributors similar ,to :test distributors @intime after the'ireleasesof relay 4,*is thereby a dividual-to the-Wire chiefandthaving their prevented: The operation of armature-1745 bank contacts? multiplied thereto, If the alsoicloses a circuit for-the lamp L ,,Which T51! e3 test connector TC is busy at this time, i; e., includesuiormally fclosed contactsr59 Their-2a is inuse'in some other connection by some lighting of the lamp L iand ther-busytoneni other operator, ground potential will "be heard in the Wire chiefs receiver indicates 11 05" a presenton the bank contact 353, since relays the-wire chief that the test ConneotoIiTC, in-ov 361 and 362' will be in anoperatedposition dividual to'the group terminating thegline; so

Then, after the release of relay 306, a-'-cir- I to substation A is. busy.- 5:2, 2r cuit is closed, extendingfromflthe ground While'itis possible'forathe'Wire chief to, b raytof ki o t t and armature Wait-on the line untiltheltestconnectoriTCw 36S, bankcontact353, private test Wiper 343, becomes idle,-he Willin all probability re armature 336' and resting" contact, Winding move the'plug P from the jack J? and re-;

V of busy relay 308, and through the -Windinsert theplugwin oi ej k1 n r ing of the. slow acting relay-307 tobattery. trunk in preparation: for, testing lines: in- WVhen relay 306 is in an operated position, some other hundreds group.) Whentheplug ground potential is maintained on both -P isriemoved from the 'jack J direction terminals 01' the Winding of relay 308. Busy ground is removed from the upper terminal-1 relay 308 is preventedfronroperating*unt-il "of the Winding of relay 204: by }the separw 5. the release of slow actingqfrelay 306 but tion of contacts 1218, thereby permittinglthe, operates before relay'32in -the testcord has operation-ofre1ay203 over a ,circuitffrom had time to fall hack. 1 By the release of slow ground through the winding "of" relayi acting relay 306 this groundpotential is 2 3,-W0rking,Gontactf and armature" 215,1

removed from the upper terminal of relay through the Winding of relay. 204,-resist- 308. Relay 308 is then permitted to energize ance 217 .to battery, at: "the same ,timei;

over the previously traced-circuit, assuming maintaining relaym20tT- operated. :Relaym the test connector TC is busy, at the same 203 energizes and places a holdingbridge 1 0 time maintaining'relay,307 in an operated "across the operating conductorse222 and;:221w

position. it In 0p'erating,relay 308 opens a at armature 211. Theioperation of arma-ia point in the initial energizing circuit ofgretures2l2and=2l3 'performszno useful funca-uw lay 309 at armature 333, opens the circuit tioniaat' this time." Removingtheplu oi the rotary magnet 312 at armature 331, from the jack J also opens theueircuitfofiiw and closes a circuitfor the reversing relay relay' 20li Relay 201 releases cand 'restoresi 301 at armature 332. -Any further actuation i its armatures to normal, removingthe ini.v of the calling device would not effect further tialbridge at-armaturew207 i. operations since the 'circuit 01"- the rotary At a later time the Wire: chief mayremagnet is open-at armature 331. Relay 306 sume thetestin of linesin the first one bun-11 2 would be energized, operatingits armature dred group and he :mayreinserttlie plug P )v 325, but since ar1nature333 is operated, reinto the jack J 1 By the olosureqofspringsfl lay 308 isnot short circuited. Tl1us,;as'long 218 direct ground is again; placed onwitheiy, as ground remains on the contact 353, busy: upperiterminal ofrelay 204' again short cir- 1;,

relay 308 will be'maintained operated. r cuiting relay 203. Relayw203 deenergizesw Relay 301 energizes over the previously and opens thefholding :bridge at armature 5;; traced circuit, and by the operation ofl'its 211.v Relay 201 again energizes and-, eloses armatures 315 and 316 reverses the directhe bridge at armature2207andagaino errtion of current flow over the operating conates armatures r206 and.208 Due to the s 0ft? ductors 221 and 222; and through the polar-v circuit-inggofrelay atzthisa'timeathis 're-Lw130 lay ssumes a slow actingicharacteristic and tliereforedoes not deenergize and open the bridge at armature 3211 until the initial bridge has been closed at armature 207. When the test connector becomes idle,

which may have taken place before, or-Inay.

take place after the plug P is reinserted into the jack J from the test contact 353., The removal of groundfrom test-contact 353 opens the circult forre'lay308 and .relay 307 Relay 308 de-energizes and opens a circuit for. the reversing relay301 at armature 332, causing relay 301 to deenergize,-and' closes the initialenergizing circuit for the wiper switching relay 309 at armature 333 and the rest-:

ing contact, which .may be traced from ground by way of the working contact and armature 322, resting contact and armature 333, arinature 325 and'the resting contact, armature 328* and the working contact, through the winding of relay 309 to battery. Relay 309 operates and'open's another point in the circuit of therotary-niagnetat armature 334, establishing a locking circuit for itself at armature 337 independent of armatures 333,- 325, and: 328; prepares the circuit for'testing the subscribers line for the busy.

or idle condition described lnore-indetailx.

later-at armature 335; opens the testconnector test circuit at armature 336; and closes the impulse repeating circuit for the test connector T6 at armature 338,-thiscir- I cuitincluding armatures 338and 320, wipers 3 14 11(1315; bank contacts 354% and 355, and

the upper and lower windings of the line relay 361; I Line-relay 361 operates, closing a circuit for the release relay 362 at armature .367. Relay 362 operates and places ground potential on the test contact 353 at armature 368 to guard this test connector againstbeing.

ating. conductors 221 and 222 is reversed.

back. to normal, therebycausingv the release of thepolarized relay 5, assuming that the test plug P is injack J 'Releaseof armature 16 disconnects thebusy tone. and the re-.

lease of armature 17 opens the holdirigcie" cuit for relay 32 and causes the extinguishing of the-lamp L Thedeenergization ofrelay 32causes the deenergization of relay 31,

both relays f releasing their armatures, with the result'as described previously. The removal ofnthe busy tone and the extinguishing of the lamp L gives the wire chief inground potential is removed dication that "the test connector has, been SB1ZGCliZEi'16l-lll13ll heinay resume dialling the" 7 :remaining digitsof the required number.

Responsive to the impulses. produced by] '70 dialling the third digit, the line relays and 303 again deenergize correspondingly.

Relays 306 and 307; are operated as pre-.

yiously described, but perform no, useful function at thistime. The circuit of the line relay 361, however, 1s opened each time the armature 320 falls back. Therefore, relay 361 decnergiz'es in synchronism' with the p deenergizations of the'line relay'303 The first-timerelay 3 61 deenergizes, an impulse of current is transmitted to the vertical magnet 365 over a circuit which maybe traced from, ground by way of armature 367 and, th'erestingcontact,armature 369 and the working contact normally closed springs "372 through the winding of the series relay 363, through the winding of the.

verticalinagnet365 to battery, In response to thisgenergization of the vertical magnet 365, w pers 3746-376 are raised opposite the first lev'el of bank contacts. At the same time contacts 372 are opened and'contacts 373, are permitted to close. The series relay 363 operates and prepares a clrcuit for the, remaining mpulses to the. vertical magnet;

at armature 370 andthe working contact. ,The remaining impulses to, the vertical unagnet now traverse a path-similar to the path of the initial impulse,,except that now contactsST 3 and armature 370 and the work ingcontact are included and contacts 342 are excluded. gacteristics, relay-363 remains in an operate viposition during the transmission of th seriesof impulses. In response to'these inipulses, the switch. wipers 374.37 6, inclusive, are raised step by step until they are opposite ,the level of'bank contacts corresponding to the third d1'g1td1alled-by the wire chief.

At theterniination of the diallingof the third digit, seriesfrelay 363 deenergizesand preparesfa circuit for the rotary magnet 366 at armature 3T0 and'the resting contact.

I The Wire chief may immediately dial the fourth digit or last digit of the number of the desired line. In response to the impulses Due-to its slow acting charproduced by the dialling ofthe fourth digit, 5

line relay 303 is againdeenergized a corresponding number of times. Each deenergization of relay 303 causes a deenergization of the line relay 361. Each time armature relea es, an impulse of current is transmitted from ground by way of the armature. 367s and the resting contact, armature and the working contact,- contacts 373, armature370 and the resting contact, through the i winding of the rotary magnet 366 to battery. In response thereto, the wipers 374F376 are rotated into engagement with the set ofbanh lcontacts terminating. the line to substation A. If the line to substation A is busy at to the Well known method of marking a busy line. As previously described, slow acting relays 306 and 307 are energized during the nnpuls ng periods.v

At armature 324 a point in the testingcircuit'of the subscribersline is held open and at armature 327 another point in this circuit is closed, The testing conductors 5323 and 324 are also maintained disconnected from the Wipers-341 and 8 16 at armaturcs 326 and 330, respectively, At

the termination of the impulses of the final digit, relay 306 deencrgizes and, assuming the line to substation A is busy, a circuit is closed from the ground potential on bank contact- 378, Wiper 375, bank contact 352, WiperSetfZ, armature 335 and the Working contact, Working contact and armature 8:27, armature 324 and i the resting contact, through the Winding of the reversing relay 301 to battery. Relay 3G1 operates and rererscs thedirection of current flow over the operating conductors 22l and 222, as

described. previously, and prepares a hold ing circuit for itself at ari'uatu-re 31 i and the Working contact. Shortly after the release of relay 306, relay 307 deenergizes and permits the closure of the contacts controlled by armature 327, thereby completi the holding; circuit for the rerersing' relay 301, which circuit-is similar to the initial circuit forthis relay except that it includes Lll11lture 314 and the Working" contact and excludes armatures 324i and 327.

The reversal of the direction of current flow over the operating conductors again causes the operation of the polarized relay 5, which functions to connect the busy tone to the receiver circuit and causes the lighting of the lamp L at thesame time preventing the release ofthe relays 32 and 31. The

lighting of the lamp L and the audible busy tone indicate to theWire chief thata lousy condition exists" on the linewith which he WiSlIQS connection. This busy condition may either be due to established connection between this substation and some othersubstation, or it may be a ialse busy condition caused by any one of several conditions, such as a short circuit on the line or the grounding of a conductor of the line. v

The next duty of the Wirechief, is to erify aiis lousy condition, i which he does by throwing the listening key, designated TALK, and listening for conversation. By

the, closure of contacts 58 andoG, conductors 21 and 23 are connected across thetip and ringconductors of the test cord C, respectively. The separation of springs 59 opens the holding circuit for relay 32, and also opens a circuit for the lamp L Relay .32 therefore deenergizes, opening; the circuit of relay 3 1 which in turn deenergizes shortly thereafter. By the closurefof springs 56,

through the slow which causes the separation of springs 755 a circuit is again established for rlayBOl,

which may be traced from 'ground by Way of armature 13 vand the resting contact,

acting relay 3, normally closed contacts controlled by armature 8, conductor 522, closed contacts 56, contacts 57,

contacts 52, sleeve of plug Pf, sleeve of jack J through the winding of: relay 201, and

through the upper Winding o'fxrelay 202" to battery. The resistance of the \vindingof relay 3 is approximately the'sa-nie as ,the value of the resistance 41. Again relay 202 is not operated, but relay 201is energized, opcrating its ari'natures 206 and 208, as pre 'viously described, andestablishinga holding bridge at armature -207, for maintaining the succeeding automatic switches, namely, the test distributor TD and test connector TC, in an operated position; The gdeener gization of relay- 1 which followedthe release ofrelay 32 disconnectsthe bridge including the calling); devices and relay 5.

Relay 3 operates over the abovetraced circuit and opens the receivercircuit at armature l2 and closes the circuit for relay 2 at armature llv RelayQ operates and closes a new circuit forrelay, 201 at armature 8 and the Working; contact by disconnecting the ground through the Winding of slow-acting relay 3 and substituting therefor ground through its own ,Wiriding The resistance of the inding ofrelayQ is substantially the same as the value of resistancey-H. Thus, the value of the current flow through the re lay 201 still is maintained insuliicient to cause the operation of relay 202, tures 7 and 9, the telephone set is connected across the conductors 21 and28, connected to the tip and ring conductors of the test cord C, respectively, the recei -Ier circuit fina y being closed when the slow acting relay 3 deenergizes and r i 12. 1 By" holding the remix er circuit open at armatur 12 a short time after the operation of relay2, condenser 29 isgiyen suihcicnt time to-beconicgcharged to the potential eigistr g :acuoss the lines so that when the cation, 1025. r a, r y r Since the telephone set is nowconnccted across the tip and ring conductors ofthe test cordC, the Wire chief will hear the talking of the subscribersengaged in conversation it the line is busy, due to, an established connection. It may be assumed that ,the Wire chief I hears conversation. The Wire chief may then either, Wait until the conversation has ceased and the subscrihersphave replaced thelr recelvcrs and thencommence the per;

7 At armae leases its armature r placed, the direct current bridge acrossthe line con uctors 391 and 392 to which the test conductors"223 and 22 1 are connected is opened, and the ground potential is removed from the private bank contact 378. As a result-, the circuit for the reversing relay 301 1 1 is opened. lielay 301 deenei glzes ano reverses the current supply COllllGCtlOIlS to conductors 221 and 222 back to normal and at armature 314: and the resting contact closes a circuit which may be traced from ground by way of the working contact and armature 317. restin contact and armature 314 1 b 7 springs controlled by armature 327, working contact and armature 335, wiper 342, private test contact 35-2, wiper 375, private test contact 378, through the winding of the bridge cut-off relay 382 of the line switch LS, interrupter springs 389, through the winding of magnet 383 to battery. 7 The re sistan'ceiof relay 382 is sufficiently high to prevent the operation of magnet 383st this time. Relay 382 operates, however, and, due to a mechanical interlocking arrangement between relay382 and relay 381, the arina tures of relay 382 are permitted to break contact with their resting contacts but are not permitted to make contact with their working contacts. Thus, the line cenduc tors 391 and 392 are disconnected from their normal battery and ground connections. Test contact 37 8, and the test contacts multiply connected thereto, are again at ground potential to prevent the line to substation A from being connected to by some other connector. When the wire chief is ready, he may commence the performance of the required tests on the subscribers line.

If theline to substation'Ahad been idle at the time the test connector'wipers 374% 376, inclusive, were rotated into engagement with the bank contacts 377-379, inclusive, the-reversing relay would not have been operated and relay 382 of the line switch LS would have operated immediately following the deenergization of relay 307 of the test distributor TD. The wire chief would have. received noobusy signals and would have then been able to commence the testingoperations immediately.

Had the wire chief heard no conversation after theilistening key had been thrown, having been given the busy signals, he would have assumed that the busy condition was false and would have proceeded to make the necessary tests to determine the nature of this false busy condition and then make the necessary report or send a trouble man out to locatethe trouble, according to the practice of the telephone company.

In such a case, if he wishes, he may withdraw the plug'of the test cord from the ack without releasing the connection to the line in trouble. To describe the operations under such procedure, it will be assumed that the busy test was false, and'after testing the nature of the trouble in the well,

known manner, the wire chief removes the plug 1 from the ack J As previously described, withdrawing the plug P fromthe jack J permits relay 203 to operate in series with relay 20 1, and causes the deenergization of relay 201. By the operation of relay 203, a holding bridge is placed across the v operating conductors 221 and 222 at armature 211 and its working contact; ground potential is placed on the heavytesting conductor 223 at armature 212 and its working Contact; and battery is placed on the heavy testing conductor 2% at armature 213 and its working contact through the lower wind-' ing of relay 202. Since it has been assumed that the called line tested busy, the existing trouble must either be a shortfcircuit across the line conductors or a ground on the negative side. 'Relay 202, therefore, operates over its lower winding as soon as armatures 212 and 213 are operated. Relay 202, in operating, closes a circuit for the supervisor lam L which ma be traced from ground by way of armature 212 and its working contact, armature 206 and its resting contact, armature 209 and its working contact, through the lamp L to battery.

The operation of armature 210 performs no useful function at this-time. As long as the trouble on'the line of substation Acexists, lamp L will be lighted; During this time, the wire chief may test otherlines in some other hundred group or perform other duties as he chooses. a I

As soon as the trouble on the line is removed, thecircuit of relay 202 is opened. In deenergizing, relay 202 opens the circuit of lamp L The extinguishing of the lamp L? indicates to the wire chief that the trouble has been removed, whereupon he may resume the testing of the line when he is ready.

This invention is not particularly con cerned with the performance of any new tests. It is, therefore, thought that a cursory explanationof the various keys shown and their functions will suflice. Only a few ations open the circuit for the line relay;

303 of the test distributor TD which deenergizes and opens the circuit of the line relay 361 of the test connector TC at armature. 820. Relay 302 remains energized, however, over 'a circuit which may be traced from ground through the. Winding of relay 302, normally closed contacts controlled by armature 315, conductors 221, normally. closed contacts controlled by armature. 206, tip of jack J tip of plug P, closed contacts 60, through the resistance at the CONN ELSE key to battery. Relay 304- is maintained energized from ground by \VELY of the Working contact at armature 318, and the release circuit for the test distributor is maintained open at armature 321. The release of relay 361 opens the circuit of relay 362. :W'ith both relays 361 and 362 in a deenergized position, a circuit is closed for the release magnet 367, which operates to restore the test connector TO to normal. I

The ECO he is provided tocnable the wire chief to deenergize the bridge cut-off relay of the called line and permit thet ests ing of the said line in the direction of the automaticswitchboard. lVhen the RC0. key is operated, a point in the circuit for relay 31 is opened at. contacts 58 and alocking circuit is prepared for relay 32 at contact 61. llirect ground placed on the sleeve couductor at spring 62, at the same time discon; nectiug the ground connectionto the sleeve which includes the resistance 1-1 Direct ground on the sleeve conductor permits sufi t current to flow through relays 201 and ){L to Relay 202 by operating its armature places ground potential on the. opera conductor by Way of armature 212 the restingcontact, and opens a point in the lirithre across conductors 5221 and222' at the springs controlled by armature 210. The circuit of relay 3G2 isthus opened. Thisrelay dcenergizes and removes ground from the private test. conductor 393 at armatum @213 .llela y 303 is maintained opcrated from ound supplied to the oper n53, conductor a 3. By the removal of' und from the private test conductor the circuitfor the bri ge cut-oil relay 382is opened. Relay 382 then deenerg'izes and permits the subscribers line to be testedintlie direction of the automatic switchboard. fornor nai hitter and ground connections. A d alling t may also be made on the subscribfunction of the battery cause the operation of relay 202.

k device S returns to normal, relay 32 ocksover a circuit "from ground at arma-. ture 3S and the. working contact, closed springs 61, through its winding to battery. Relay- 31 notoperated since its circuit pened at springs 58, Restoringitlni BCO key opens the locking circuit of relay 3,2 and restores the relay to normal.

The talk ng and listening key, designated TALK, has. been described in connecti with the setting up of the connectionto the lineto substation A; The function of the ringi. key, designated and needs no further explanation. The cut-in key desig nated Btlluis to supplytalking current to the line and give supervision when a connection betwe the trouble man and the Wire chief has -.en established over a trunk, such as the trunk rern'iinatinfr in the jack JF". A. connection of this kind will be described subsequently. Y

To test the suljiscribers line for the pres once of foreign battery, the ground key. des

ig'nated GED, is operated. \Vith the GED l 'ev operated,groundis connected to one ride the volt meter V. The ring side of'thc line, remainsconnected to 'the other side of the volt meter- V. If a foreign battery potentiale its onthe ring; side of the line the volt meter V Will be deflected, To test the ide'of the line for foreign battery, the reversing key, designated REV. is thrown. in: addit on to the GED key. Throwing the REV keyreverses the tip and sing conductor connections With respect to the voltmeter. Ineither case, if the volt n'ieter deflection in areverse direction. the voltmeter reverse key, desio'natcclvlilll. is also thrown. This 18\ '61SOS Il10 connection to the volt meter. p I

T he rin r side of the line may be tested for ground. by operating the key and either the highscale or the low scale volt i'netor key, designated l lfil and L3 res ec To test the tip side "of thefline for the ground key andlh'e res key REV are thrown, in addition to cit ier the low scale or high scale volt meter key. Other. functions of theloW scale key and the hi .rh scale key. as. shown in the draw; iiigs will suggest themselves to those skilled in the'art, and need not be further d escribed. I

J fterfthe Wire chief has performed the necessary tests on the line of substation A, he most probably will \yislrtojperforni ,simi-f la r tests on another line, .The line that vvill probably hetested next the line aminae in thencxt set of bank contacts in-a same level inlvvhich'the line of substation RING, is obvious- TD to normal.

terminates, since the wire chief need dial only an'extra digit 1 to establish connection with this next line. In response to the dialling an extra digit 1, a single impulse is produced, causing line relay 303 to deactuate momentarily. as described before, and open the circuit of the line relay 361 at armature 320. Relay 361 fallsback and sends animpulse of current to the rotary magnet Rotary magnet 365 operates to rotate the switch Wipers 37 l376, inclusive, into engagementwith the next set of bank contacts. The wire chief ,may then .test the line terminating in this set of bank contacts. The

testing of this line for the busy or idle con dition will take place in a manner dentlcal to that in which the line to substationA was tested -for the busy or idle condition. It is apparent then, that connection. maybe es tablished with each line terminating in the same level of connector bank contacts, con secutively, by dialling anotherdigit 1. To obtain connection with the line terminating in 'a different level of the bank contacts, the connector release key is operated, as described above, to release the connector TC and the last two digits of the directory number of the subscribers line, to which connec tion is desired, are dialled.

The operations which are performed and which take place to release the entire'con- .nection may now conveniently be explained The wire chief first withdraws the plug P from the jackJ As described previously, this operation permits relays 203 to operate in series with relay 204: toestablish the holding bridge across the operating conductors 221 and 222 to armature 211. To release the entire connection, the wire chief operates the key K momentarily, which short circuits.

both relays 203 and 20 1. Both relays deenergize and allow their armatures to restore to normal. T 1e removal of the bridge across the operating conductors at armature 211 opens the circuits for both relays 302 and relay 303. These relays fall back and open the circuit of relay 382 at armature 31'? and open both circuits "for the release relay 304 at, armature 318 and armature 319; Upon the release oftherelay 30 1, a circuit by way of armature 319 and the resting consprings which was closed'upon the first vertical step of the switch wipers,through the winding of the magnet 310 to battery. Release magnet 310 operates and restores the switch wipers to normal; In deenergizing, relay 304: also opens the circuit of the wiper switching relay 3O9- atarmature 322, thereby restoring the circuits of the test distributor Furthermore, when line relay 303 deenergizes, the circuit of line relay 361 is opened at armature 320. Relay 361 deenergizes and opens the circuit ot'the'reis closed which may be traced from ground lease relay 362. Upont-he release of relay 362, a, circuit is closed which may be traced from ground by way of armature 367 and its'resting contact, armature 369' and its resting contact, springs 371, which are closed upon the fist vertical step of the switch wipers, through the winding of the release magnet 36% to battery. Release magnet 36a operates-to restore the switch wipers back to normal.

It will now be convenient to explain a certain function of the relay 4 in the tele phone set TS, which heretctorehas not been described and which makes it possible to operatethe calling device with the talking key thrown without producing annoying clicks in the receiver. For the purpose of explaining this tuntion, it may be assumed that the plug P has been inserted into the jack of some trunk terminating in the wire chiets position, and that the TALK key is the off normal springs 19. Relay lcener gizes and opens the receiver circuit at armature 15, and closes a circuit for relay 32 at armature'l l, as previously described. By the operation of armature 13, ground is placed on the upper terminal of relay 2, thereby causing the deenergization of relay 2, In deenerglzing, relay 2 disconnects the telephone set from across the test conductors. When the calling device returns to normal, the circuit of relay 4 is again opened at springs 19.v Relay .41, thereupon deenergizes, closing a point in the receiver circuit at armature 15, and again closing the circuit for relay 3. Againthe operations concern- 111g relay 3 and relay 2 take place and the telephone setis connected across the tip and ring conductors of the test cord without the receiver. p

In a previous paragraph in this specification, it was mentioned that should the wire chief find-a subscribers line out of OitlGlK a trouble man may be sent out in the held to remove the trouble, after thenature of the trouble had been determined, It will now be assumedthat the wire chief did not care to maintain connection with the line in trouble, and released the connection thereto as described above; 5 It will furtherbe asproduction ofthe usual annoying click in the" sumed that the trouble man is out in the held and has made certain repairs upon a'subscribers line and now wishes to establish a talking connection with the wire chief. The trouble man will connect his telephone 'ling the proper code, this selector and another selector are operated in the Well known manner to select and connect with a trunk terminating at'the Wire chiefs positron, the latter selector contained in thegroup in Whose banks the trunks terminating in the Wire chiefs position reserved for this special purpose are accessible. ltis assumecl' that the trunk comprising conductors o23- 525, inclusive, is the trunk selected. Responsive to a relay operation in the latter selector, a circuit is closed for relay 503 which extends from the bridge across the conductors 523 and 524i, resting contacts and arn'iaturcs and 510, through the upper and lower Winch ings of relay 503' to ground and ba.ttery,,re spectively. Relay 503 operates and closes a circuit'for the line lamp L at armature 512; connects a ring-back tone to conductor524= at armature 513', supplied from the ringback tone machine RB' and at armature 514 closes a circuit for the slow acting relay 504. Relay 50 1 operates and places ground on the private conductor 525 at armature 515 for the purpose of maintaining the previously operated selector switches associated with the connectionin an. operated position. A holding circuit for relay 501 is also prepared at armature 516.

In response to the lighting of the lamp L, the Wire chief inserts the plus; P of the test cord G into the jack J The resistance of the upper Winding of relay 501 and the winding of relay 502 are such that both these re lays are energized over the circuit which may be traced from ground by Way ofarmature 38 and its resting contact, resistance 41, contacts 55, contacts 57, contacts 52, plug P. sleeve. of jack all", contacts 518 closed when the plug is inserted into the V jaclcJ, through the upper winding of relay 501, through the Winding; of relay- 502 to battery. Relay 502 operates and disconnects the windings of relay 503, from the conductors 523 and 524. at armatures 509and 510', respectively; and closes another circuit for relay 50% at armature 511. Relay 501 energizes and closes a loclringcircuit for itself at armature 507, Which may be tracedt'rom ground by Way of the working contact and armature 516, armature507 and the Working contact, through the lower Winding of relay 501 to battery. The ring-backtone is disconnected from the line conductor 524at armature 508,the circuit of line lamp L is opened at armature 506 and the resting and pre sleeve of contact, and a circuit is prepared for the llQldilZlilHITI J at tllQlVOIlilIlg contact of this armature- .Relay 503 deenergizes, maintain ing the circ uit'of the hold lamp L? open at air-n" iii lli ljelllllgi key, designated; TALK, which initiates the operation of relays. 3 and 2-10 connect the telephonesetTS across thetesting conductors and alsooperates. the BCI key to furnish a talking current supply for the transmitter of the trouble mans telephone set. The wirechiet may now converse with the trouble man and receivesuch information or instructions), as might be given.

This, trunk circuit is so desi ned that the;

circuit including its lower Winding. Relay 502. will deenergize and. again connect the upper and lower windings. of relay 503 to the conductors 528 and 52 1- at armatures 509 and-510 and their resting contacts,

respectively. Relay again operates and tablishes the alternate circuit for relay 505:

at armature 514 before it has had time to deenerg'ize when its circuit isopened at arma ture 511. At armature 51.2, a circuit is closed for the hold lamp L9. The lighting of this lamp indicates tothe Wll'GIClllQf that the, trouble man, has not disconnected his telephone set fronr the subscril'iers line. Should the Wire chief again, wish ,to establish a talking connecti-onto the trouble man,

JTthercby again causing rclayy502, which in turn causes the dcen: ergizationof relay 503.

To release this connection, the Wire chief again withdraws the plug P from the jack he mayreinserttlm plu intothe jack J which causes the dccnergization of relay 509., as described above." Again relay 502 is connected across the trunk lines and 524k lVhen the trouble man disconnects the telephone set from across the subscribefls line, relay 508 also deenergizcs. lVith both. relays 502 and 503 in a dcenergized position, the circuit of relay 504 is opened. Relay 50 1 deenerg'izes and opcnsthe locking circuit for relay 501 .at armature 51 6 and removes ground from the private conductor 525 at.

armature 515. The removal of ground from conductor525 causes the release of the sueceeding select-or switches in the well known manner; Relay 501deenergizes. placingthe trunk circuit inits normal condition,

The ire chiefs position isslso provii ature'512. The Wire chief then operates.

In such a case, should the operation of of the testing cord into thejac; J at which the trunk in question terminates. Insorting the plug P into the ack J*, close, a circuit for relay 401 from ground at springs 418 through the upper winding of relay 401 to battery. Relay 401 operates and at armature 406 opens a point in the circuit over which relay 402 is later to be held operated; connected the conductor 424 to the ring of jack 5" at armature 408-; and

at armature 407 andv the working contact, closes a circuit which may be traced from ground by way of armature 38 and its resting contact, resistance 41, contacts 55, contacts 57, contacts 52, sleeve of plug l sleeve of jack 5", tnrough the lower winding of relay 401, workingcontact and armature 407, through the winding of relay 402 to tery, at the same time opening a'point in the circuit of the lamp L at the resting contact of this armature. Belay 4-02 operates and prepares a point in its holding circuit at armature 409; prepares a point in the cir cnit of thelainp L at armature 410; and closes a holding bridge across the conductors 423 and 424 at armature 411. By vfrtu'e of this bridge placed across the line conductors and 424, the line switch individual to this trunk line is caused to operate and select a. trunk to an idle selector switch in the well known manner. it armature 4L2, shunt is placed around armature 409 for a purpose to be described later.

The circuit is now prepared for the operation of the calling device according to the number of the substation with which connection is desired. When the calling device is moved off normal, relays in the test cord operate, previously descrioed, to remove 'trround from the sleeve conductor, thereby opening the circuit of relay 402. Relay 402 deenernizes and at this tune fun tons to open the holdin brid s across the conductors D 32' 4 23 424 at iature 411.. unsy meting the impulses produced hy the calling device to be tran: nitted over the condu'ctors and 424 to operate the. automatic switches in the exchange. {"Jhen the 'callin device S returns to norms, energized which in turn opens th circuit of relay 32. When relay 32 decncr gizes, the circuit of relay 31 is opened and groundis strain placed on the release conducton, the circ .it for relav402. Bela 402 and s rain places t e'holdnighr'eg e .HCLOETS lQ E and 424 at taking place liie'tore 3i to decnergize and disconnect closu the bridge including the dial S across the one vting conductors. In response to the digits hailed by the wire chief, the auto- ;niultiples thereof.

. the removal Y vof this number. automatic switches will he relay 4 HQ will an; r

niatic switches are operated in the well known manner to extend the connection to. the desired substation the last switch functioning; to signal subscriber and finally complete the talking connection when the subscriber removes his receiver to answer the call. The wire chier" tien holds conversation with the called subscriber. a

, At the termination ot the conversation, the

called subscriber will replace his receiver-f winding of rclay40l.' Belay 402 deenergizes and at armature opens the hr:

including the winding of relay 40.3 across the conductors 423 and 4* i. as result. the automatic switches associated with the connection are released in the well known man ner.

nate circuit for relay-402 is opened. Relay 401 'deenergi es, releasing its armatures and disconnecting): conductor 424 from the sleeve the jack o at armature 408. The energi ing or winding of relay 401 for the purpose or" preventing relay 401 from deenergizing un til after the circuit of relay 402 has been opened. This prevents relay 401 from tallbaclz before relay 402 and also relay 443 have releasec. their armatures, thereby pre- "renting; relay 402 from becoming locked in anoperated position from ground at armature 406. The replacement of the receiver atthe called substation initiates the release of the final connector switch, as. is well known in the art.

Calls may also beextended to the wire chief over the trunk line comprising conductors 423 and 424 by dialing the number assignedtothe wire chief for general service. this trunk line being accessible at the connector bani; contacts and 434 or To establish such connection, the subscriber removes his receiver and dials the number assigned the wire chiet for ncral service. in i l l the iecc' and the dialling);

operated. the in 1. switch operating to e tend the connection to th an; cents. s and and apply Sigilulllng on .i: there-- to. In response to this signalling current. relay 403.v which is'bridged across the contors 423 and 424in series with the com @3417, will energize and close a circuit clay 402 at armature'4l2. Belay 402 1.1. :1 close a locking CiTCciicffOI nature 409; and close a circuit for theline itL'tT-Q L which may be traced from ground the resting contact and armature 406, armature409 and the working contact,

At armature 412, point in the altcn,

ircuit. for relay 402 includes the low-- lit) jack u armature 407 and its resting contact, ,working contact and armature &lO,th:I' ugl1 t l 1e linelamp L to battery. At armature 511 1 va bridge which is later to be closed ,acro s s the conductors and 42415 pre Jared.

p In response-to the lighting 0t the lamp L the wire chief inserts the plug P into the Inserting the plug P into the'jack J, results in the closure otthe circuitffor the upper winding of relay lOlnt the Springs -4;l8, and in the preparation of an alternate rent bridge across the conductors 423 and 42 1,, which includes the winding of relayg ellld and the working contact andzirmaturell.

; across the conductors 41-23 and 4241 causes the operation of a relay in the connector switch which disconnects the signalling current and finally vcompletes f the talking connection.

Conversation between the calling subscriber and thewire chief may then beengag ed in, .and at theend of tllQCQIlVGYSELtlOII, the re lease of the. automatic switch and the restoriation of therrelays in the wire chiefs telephone set and the relays in the trunk circuit,

namely, relays 4:07,; 402, iand403,takes place in the manner describedabove. 7

in small telephonesystems, as suggested 0 in the in t peragraphs of the specification,

the operat l at-thewFre chiets position may be required to perform the duties, not only of a wire chief, but may also be required to perform the duties ordinarily assigned to a soralled zero operator. A special group of trunks may be provided, terminating at the wire chicts pos tion for this kind or service. The trunk line comprising conductors 071-678, inclusive, terminating in the jack J, is one of this group oftrunks, con nection with wh ch is obtained hydialling the digit 0. This trunk, therefore, is acces sible in the tenth lei 'el of thefirst selector 'sw'tch, banks Should a subscriber have difficulty in completing some certain connection,v he would make a report oi? th s fact by replacing his receiver and again removing it and dialling the digit 0 and inform the operator answeing accordin 'ly. In the presentv assumed case, the wire ch ef would answer the call, would determine the number I of the subscriber with which the calling sub scriber wishes a connection, and would then proceed to extend the desired connection by Yof armatu dialling the desired number ,for the calling subs f ber, all 'nns'teing 'dorie byinean'sfof tlie s ngle ending cordlsC, shown infliig.f6.

It inayl be assumedthen, that certain subscriber has had difliculty in obtainingio connect on "with certain other subscrlber and after replacing his receiver, he removes tthe second time and dials ,thefidigit O to infornr'the"zero operator oflhis dii iiculty. In response to ,th'eseco nd removal of the,75

receiver and the dialling of fthedig'it 0, a first selector sw tch operates to selectan'idle trunk which, it :will" he assumed, is the. trunk terminating in the jack By reason of the direct current bridge across the subscribers conductorshi'l and .(iTS andthe upper muss flower windings ofthere'lay fiw. Belay 652 operates and connects the ringback to'ne curr'enti to conductor 671 at armature 6 59, conductor 53,0 belngconnectcd to the r ngsback tone machine RB, Fig. The ring-hack G tone heard'by thecalling suhscriber assures The placing of this d rect current budge hiinthat'the connection has beenextended toan operatorts position. At armaturetiQO, acircultis closedfor thecall lamp. L which may be traced ifrom groundfhy way of the 9 circuitjfor the second 'slowa ctiiig relayf654 f at armature 662 and places groundfpotential on the .priyate conductor T672 n armature l 6 63,for the jmrpose of lroldinl ifltlieprecedlng switches n an operated positron. Relay 654 operates, actuating its armature "664.

The function relay Q6541" will becoine ph ions from the description of laterfo'p'eracapacity of a zero, operator, inserts the plug P? the/jack ilfiiind ,throwsjthe key, designated 'ALKQfor lis iningi "As airesult f of the former opera closed torthe upper winding ofcr eley ($51," which may traced from lgj roundibyiway I 607 andits resting contact,contacts 6 11,;1esistance ,610, sleeve of the plug 1 P, sleeve ota ck J contacts665, whichllire mechanically closed when {the plug I E is inserted into the jack J through the upper winding of relay (351 to battery. Heaven operates andfldisconne fts thering hzicl; tone ,jtronrconductor V671 atarmature ,656; closes a holding circuitfifor its lower winding at m-1e'nur 657,(which inny: be tracedjfrom gnoundi by, way of. tl'ie worltin'g' ontact and armature,660, arnniture 657 and the working en, througlrthe lower winding of relay acting relay cssf pe rtsend closes a ion, a circui t is 5 651 to battery, at the same time .ing the circuit of the lamp If by armature .8, conductor 22, conductor 22,

ing contact of this armature. An alternate ground connection which is .later to be applied to conductor 672 is prepared at armature 658.. It will be seen that relay 602 in the cord'SG can not operate at this time by reason otithe ground on both terminals of its winding' Throwing the TALK key bridges theconductors 21' and 23 ross the tip and ring conductors of the single ending cord SC. A circuit is also closed forrelay 3 1n the wire chiets telephone set.'wh1ch' may be traced from ground by way of armature'13 of the resting contact, winding oi relay 3, normally closed contacts controlled contacts 618, sleeve of plug 1?, sleeve of jack scriber.

J, contacts 665, through the upper winding of relay 651 to battery. telay 3 operates and causes the operation of relay 2, this latter relay operating to connect the telephone set TS across the conductors 21 and 23 connected toconductors 21 and 23 in the hereinbetore described manner, this taking place without the production of an annoying did: in the receiver R. The wire chief may then converse with the calling subscriber, and after learning his difficulty and the number with which he desires connection, he informs the calling subscriber that he will attempt to complete the connection for him. The wire chief then throws the key, designated DIAL, tor dialling, and dials the'number of the called sub- Operating the DIAL key'disconnects direct ground from the lower terminal of relay 602. Belay 602 then operates over a circuit from ground through its own wind- 111g. resistance 610, sleeve of plug P sleeve of jack Jicontacts'665, through the upper winding of relay 651 to'battery. armature 60 a'circuit for the supervision lamp L and for thelower polarizing winding of relay 601 is closed. By the separation of contacts 614 and contacts 612 anddby the closure of contacts 613 and conta ts 619, the

Bv'reason of the direct, current bridge,i'ineluding calling device S and relay 5,,now across conductors 621 and 622, the lineswitch terminating the conductors 621 and 622 and individual thereto, is caused to operate and select a trunk to an idle selector switch and prepare that switch to receive the impulses of a first digit dialled by the wire chief. At contacts 615 direct battery is placed on conductor 26 thereby prcventing the Opera disconnectat the rest position. upper wind ng of relay tion of relay 32 when ground is connected to conductor 26 by the operation of relay 1. re sponsive to the movementoi the calling device S oti normal;

. In .responseto the digits dialled by the wire chief, the selector switch mentioned above and other switches respond thereto to extend the. talking connection, the last switchbeing a connector switch which operates to extend the connection to the called subscribersline; signals the calling subscriber; and finally completes the talking connection whenthe called subscriber removes his receiver, as is well. known in the art. When the wire chicthas completed the dialling of the wanted subscribers number, he restores the DIAL key to normal. In so doing, polarized relay 601 is bridged across the "conductors 621 and 622 in series with the retardation coil 60-3 at contact 612, relay 608 now being operated. This bridge serves to hold the automatic switches associated with the connection between the called substation and the wire chiets positiondn an operated Current now flows through the I 601 in series with the retardation coil 603 from a current sup- .plv in theconnector switch. The direction oatthis current flow, however, is opposite to that necessary to cause the operation of relay 601. Relay 601, therefore, remains inoperative at present.

In response to the removal of the receiver at the called substation, a relay operationin the connector switch takes place, which reverses the current flow over the trunk conductors621 and 622 and throughthe winding of relay 601. This results in the operation of relay 601 whichdisconnects the circuit of the lamp L at armature 605. The extinguishing of the, lamp L indicates to the wire chief that the called subscriber has answered. As soon as the called subscriber removes his receiver, theconnection between this sub scriber and the calling subscriber is in condition for conversation, the talkingconnec -s tion extending from the called subscriber through the automatic switches which were operated in response to the dialling by the wire chief, conductors 621 and 622, armatures' 606 and 608 and their working contacts, conductors 621 and 622, contacts 612% and 612, tip and ring of jack 3"", condensers 666 and 66?, conductors 671 and 673, tlii'OlliiTh the automatic switches associated with the extension of the call to the wire chiets position from the calling substation.

I As described in the above parapra 'ihs, it

was assumed that the TALK key and DIAL {key were separate keys and that each could be ope-r: ted independent oi, the other. In

this case, then, the TALK? key might be operated when the DIAL key is actuated and the wire chiet dials a number. Again relay 1 has the function of initiatingoperations that disconnect the telephone" set TS from the heavy talking leads when the dial is oil normal, to prevent disagreeable clicks in the receiver during dialling. It is the usual practice, ho vever, to employ a double throw key arrangement for the dialling and talking controls, having the three alternate positions, forward, backward, and neutral, the neutral being its normal position, one of the other positions for dialling, and the other for talking, then, it is impossible to have both the dial and the talking spring arrangeinents operated at the same time. consetluently, relay l Would perform no useful function in that case, When using the cord "SC.

At the termination of the conversation, both subscribes will replace their receivers. Replacing the-receiver at the called substation causes a deone'rgization of a certain relay in the connector switch associated with the connection to "again reverse the current flow over the conductors G'Ql'and 622 through the Wll'lCllIlfl, of relay 601 "bacltto normal. Relay G01 thendeenergizes, againclosing the circuit for the lamp L at armature 605. Replacing the receiver at the calling substation opens a bridge across the trunk conductors Gift and 673, thereby opening the circuit of the line relay652 Relay 652 decnergizes and opens the locking circuit for relay 651 at arn'iature 660, and opens the circuit for the slow acting relay 653 at arn'iature G61. Relay 653 and removes ground from the private conductor 6T2 at ar lnaturefitll-l, and also opens the circuit for "the relay at armature 662, The removalof ground froln the private conductor 672 allows therelease of the automatic switches operated bythe calling subscriber Whenthe connection was extended to the Wire chiefs position. Shortly after the deenergi'zation of relay relay ldeactuates and again places ground on the private conductor 672 at armature 66 i and its resting contact.

"Ground on this conductor now prevents the trunk Vine comprising condiiictors' 671-'673, inclusive, from being seized in'the establishment of another connection to the Wire c s iosition at this time The lighting oi? the lamp L gives the Wire chief indication thatthe subscribers have completed their conversation and that the called subt'criber has replaced his receiver, whereupon the Wire chief reinoves'the plug P froin'the jack 1, This operation opens the circuitof role-vs G02 and relay 651in series, causing their deenergization By the release of the arn atures of these relays, the circuits are again restored to normal.

The invention, its utility and operation, having been described What is considered new and is desired to have tors Patent claims.

deenergizessecond slovv acting vice normally disconnected from said protected by Let is set forth in the appended WVhat is claimed isi 1. In a telephone system, a cord circuit, a calling device normally disconnected from said cord circuit, means responsive to each movement of said calling device from its normal position for bridging said calling device across the talking conductors of said ofi-norm'al position, and separate means for maintaining said calling device bridged across said talking conductors an Interval from said cord circuit, means responsive to nit with sant the connecting of said cord ci c trunk line for placing a bridge across said trunk line exclusive of theconductors of said cord circuit to prepare said automatic switch for operation, and means responsive each time said calling device is moved from its normal position for opening said bridge and forbridging said calling device across the conductors of said cord circuit to place said automatic s vitch under the control of said calling device.

3. In a telephone system, a trunk line we tending to an automatic switch, a cord circuit "adapted to be connected to said trunk line, a calling device normally disconnected from said cord circuit, means responsive to the connecting of said cord circuit with said trunk line for placing abridge across said trunk line to prepare said automatic switch for operation, connecting means resoonsive to the movement of said calling device from its normal position for connecting saidcalling device across the conductors of said cord circuit, and meansindividualto said trunk line and controlled by said connecting means for opening said bridge to place said automatic switch under the control off said calling device, said last neans arranged to replace s'aid bridge acr: said trunk line to 'hold said automatic switch operated. when to efiect the operation of suit automaticswitch.

4. In a telephone system, a cord circuit,

an operators telephone set, a calling do: cord circuit, alcey, contacts controlled by said hey, means responsive tolthe closure of said contacts for connecting said telephone set to said cord circuit, and means reiponsive to cachsetting operation of said calling device for disabling said first means and for bridg ing said calling device across the conductors of said cordcircuit While said calling device is in an off normal position.

5. Ina telephone system,

operators telephone set, a calling :device a cord circuit, an

, cord circuit while said calling device is in an I cuit adapto.

perniit said trunk normally disconnected from said cord circuit, means operative responsive to the actuation of a key for connecting said telephone set to said cord circuit, means responsive to a setting operation of said calling device for restoring said first means to disconnect said telephone set from said cord circuit and for c nnecting said calling device to said cord circuit, said last means adapted I the re-operation of said first means and to a -1 disconnect said calling crevice -from said cord circuit when said calling device returns to normal following the setting operation. i

In a telephone system, a trunk lineextending to :l to be connected to said trunk line, a callingdevico normally disconnected from said cord circuit, means individual to line and resionsive to the connccting of said cord circuit .to said trunk line for placing a bridge'across'said trunk line to prepare said automatic switch for operation, means responsive to the setting operation ofsaid calling device for bridging said calling device across the conductors of said cord circuit and for removing said bridge thereafter to permit said calling device to control the operation of said automaic switch, and tor again replacing said first bridge and then disconnecting said calling device from said cord circuit after said calldevice has v i said automatic switch operated.

7. In a telephone system, a trunk line terminating at an operatorlsposition and permanently connected to an automatic switch, said trunk line also accessible in the banks ol a second automatic switch, means for operating said second automatic switch tov connect with said trunk line, a relay bridged across said trunk line in series \vitl a condenser, said relay being operative re sponsive to signalling current from said second automatic switch for signalling the operator on incoming calls, and means for bridging said relay across said trunk line exclusive of said condenser for preparing said first automatic switch for operation on outgoing calls from the operators position.

8. In a. telephone system, a cord circuit,

, a calling device, a-telephone set adapted to be connected to said cord circuit by. the actuation or a key, relays operative responsive to the actuation ofsaid key for preventing clicks in the receiver of said telephone when s'aid'telephone set connected to said cord circuit, and means responsive to a setting operation of said calling device to storing said relays and for permit-tin, re-operation when calling device turns to normal] i). In a telephone system, a. cord circuit, a calling device, a telephone set, means for bridging said telephone set across the con automatic switch, a cord cir-' returned to normal to mainthe'said key isrestored,

doctors of said cord circuit, means operative responsive to the operation of said first means for preventing clicks in the receiver 0t said telephone set when sald hrst means is operated, and meansresponsive to a setbridging said telephone set across the conductors of said cord circuit, means'operative responsive to the operation of said first means for preventing clicks in the receiver of said telephone set when said first means is operated, and means responsive to a setting operation ot said calling device for temporarily substituting said calling device for said telephone set and for restoring said.

second means, said second means again ingoperative when said calling device turns to normal.

11. In a telephone system, a tru nk line terminating in a jack, a cord circuit terminating in a plug adapted to be inserted into said jack, a telephone set adapted to be bridged across the conductors o1 said cord circuit by the operation of a key, relays responsive to the actuation of said key providingsaid plug is in said jack and responsive to the insertion of saidplug into said jack providing said key is actuated for preventing clicks in the receiver or said telephone set produced by either operation, a calling device, means responsive to a setting operation of said calling device for temporarily substituting said calling device for said telephone set, and means for restoring said relays to normal condition when the substitution is made so that thesaid relays are enabled to again perform their function When the said telephone sctxis again connected. i

12., In a telephone system, a trunk line, a relay and a key individual to said trunk line, a shunt circuit around said relay,,contacts controlled by said key when actuated for, opening said shunt circuit, a circuit for energizing said relay when the shunt is opened, a calling device bridged across said trunk responsive to the actuation of said key, contacts in said shunt circuitopencd and a second bridge closedacross the trunk line through contacts of said relay when 13. In a telephone systen'i, a trunk line comprising operating conductors and talk- I ing conductors, a cord circuit temporarily connected to the talking conductors of said trunk line, a calling dev ce, moans respon sive to a setting operation of said calling device for connecting said calling device to

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