US1594877A - Telephone system - Google Patents

Description

Alig. 5,1926. 1,594,877

7 H. D. QURRIER ET AL TELEPHONE SYSTEM Filed Oct. 26, 1921 '7 Sheets-Sheet 1 a-8,1926. Y "IIH D. CURRIER Er AL,

"TELE'PHONE SYSTEM Filed Oct. 26, 1921 '7 Sheets-Sheet 2 17275222272" urn)?! Aug. 3 1926. 1,594,877"

- H, D. CURRIER ET AL TELEPHONE SYSTEM 7 Sheets-Sheet 5 2172183761? ETamZZZ'zzrrzPn Aug. 3 1926.

H. D. CURRIER ET AL TELEPHONE SYSTEM '7 Sheets-Sheet 4 Filed Oct. 25 1921 fizz/527701"; jfzramflfuzvzz'r Bear .2235 522712 Aug. 3 1926.

H. D. CURRlER ET AL TELEPHONE SYSTEM Filed Oct. 26, 1921 '7 Sheets-Sheet 5 fii'ramZZ :nrrzm Aug. 3,1926. 1,594,877

H. D. CURR IER ET AL TELEPHONE SYSTEM Filed Oct. 26, 1921 7 Sheets-Sheet 6 21a! W i n?? Y CURRIERETAL TELEPHONE SYSTEM Filed Oct. 26, 1921 '7 Sheets-Sheet 7 272/527 0P5. fizfamZZ 52117221" Patented Aug. 3, 1926.

warren stares issues PATENT orries.

nrnarr D. CURRZIERDE orrrcaoo, AND scone-n n. EAT-ON, or OAK Panic ILLINOIS, assrouons ro :anrroeo swircnnoann nun sUrrLY CO PANY, on cardiac, ILLINOIS, A oonronarrou or rntrnois, l

TELEPHONE svsrisrr.

Application fil ed October 26, 1921.

Our inyention relates to telephone systems and has to do more particularly with multi-o'liice exchange systems in which the subscribers stations of the same each an or different exchanges are connected by means oi"manualswitchboard apparatus and automatic apparatus, and one or the main objects of our invention is to provide improvedcircuit arrangements for a system of the above character.

In multi-otfice e1\:change systems of the above type, wherein operators are provided for manipulating the cord and trunk circuits, the operators use cord circuits for in terconnecting the lines of their own one change, but when they desire to connect with a line in a distant exchange, they conmeet to a trunk circuit terminating before a operator in the distant exchange, who, after having communicated with the A operator at the originating exchange over a special order wire circuit independent or the trunk circuits, and after having designated the trunk to be used by the A operator atthe originating exchange, connects the trunk circuit to the anted line.

Systems of this type have been found faulty, due to the fact that special order ire circuits are required to handle these trunkin connections, and due to the liability oil mistakes being made in passing the num her; to the B operator and in the assignment oi the trunir to the A operator at the originating exchange. In overcoming these objects, We provide circuits in Which the A operator is provided With trunk acirs which, are accessible from her position and Which are connected to apparatus that extends to different exchanges and terminates in plugs before B operators at such exchanges.

One of the features of our invention. is the termination of the outgoing trunk jacks in the banks of finder switches, and the in coming ends of the trunk circuits at the distant exchange in individual non-numeri cal triinlrselecting switches, so that when connection is established iv-itl'r an outgoing trunlcjaclr for extending a connection to a distant exchange, one, oi'the finder switches iscaused too-perate to seize the trunk jack. When the trunl; jack is seized the 110114111" inei'ical'"trunking switch at the distant exang k e nfm tis q t nd h qonr nection to an idle trunk leading to an idle Serial No. 510,445.

trunk operator at the distant exchanges, thus giving the, A operator an individual outgoing trunk to any operator at a distant exchange.

Another feature of our invention is the provision of an order Wire key associated With the A operators cord circuits at the originating exchange which when actuated places' her in direct communication with the B operator at the distant exchange over the seized trunk, and thus permits the direct passing ofthe callfromthe A operator at the originating exchange to a B operator at the distant exchange without the aid oi. an order Wire circuit The order Wire cir cuit is thus eliminated, and we do away With the assignment of the trunk by the B operator to the A operator.

Another feature of our invention is the means for controlling the busy indication at the B operators position. Each positionrcmains busy as long as its particular operator has a greater number ofcalls betliore her than any other adjacent operators. Means are also provided for removing the busy indication Whenever an operator has a smaller load, or a load equal to the smallest load on any operators position. i

A feature oi this busy controlling means is the distribution of the calls to the operators according to their respective abilities to handle calls.

Still another feature of our invention is a provision whereby as many as four calls may be stored at a trunk operators position in such, a ay that a distributing means is provided for incoming trunk calls in such a manner asto give each operator the same number of stored calls,in case the operators are not keeping up with the load. This storing feature provides a definite means for checking up the speed at which the incoming trunk calls are being handled at the trunk or B position.

For a more complete understanding of our, invention, reference may behad to the accompanying drawings, in which; WeillusQ trate apparatusfor nterconnecting two subscrihers' at diilerent exchanges, and which s ar s silt s -Lewisfiandt h chi when joined asshown in Fi 8, illustrate complete connection. All oi the parts have been. shown at npr nal, and the apparatus shown in Fig 1, and the letthalt of Fig.

2 is located at the exchange M, and the right half of Fig. 2 and all of Figs. 3, 4, 5, 6 and 7 is located at the exchange N. In Fig. 4 we illustrate trunk operators busy control and storing circuits f, it and j, which are associated with the operators posit-ions F. H and J, and in Figs. 5, 6 and '7 we illustrate the trunk operators sequence selecting switch circuit for selecting in sequence the calls stored at a trunk operators position.

Referring now more in general to our invention, it comprises the exchanges M and N. Atthe exchange M a plurality of substations A are provided, connecting to line circuits L, comprising the usual cut-oft relay CO, line relay LR, multiple line lamps S and multiple answering jacks J The multiple jacks J terminate before a number of different operators positions, each of which is provided with a line signal S so that when a call is initiated aplurality oi signals S are lighted, and thus a number of operators are apprised of the call. F or interconnecting the. substations a plurality of cord circuits B are provided at each of the operators positions, each cord including answering and calling plugs A? and GP con-. nected by the heavily marked talking CO11 ductors. The answering end of the cord circuit B is. provided with a sleeve relay ST, which is energized when an answering plug AP is inserted into the jack J of a calling line. The relay ST is provided with a high and a low resistance winding, and upon, the actuation of relay ST the high resistance winding is shunted and thus prevents a relay ST of another cord circuit, as B, from being energized, should the operator associated with the second cord attempt to answer the call. An operator of another cord attempting to seize the call after the first operator has connected to the calling line is prevented from communicating with the subscriber as the low winding of relay ST of the first cord prevents the relay ST of the second (0rd from operating. As the second operator is not connected to the calling line, due to the relay ST of the second cord remaining normal, she does not receive an answer from the calling subscriber and withdraws the answering plug of her cord circuit from the connected jack.

an answering supervisory relay AS is also provided and is actuated upon the energizetion of relay ST, and the said relay AS upon actuation prevents the premature lighting 0]": the answering supervisory lamp AL. A listening relayLS is also provided and is actuated in response to the energization of relay ST to connect the operators set 0 to the cord conductors. A link disconnect relay LD is provided which is energized when the calling subscriber replaces his receiver after finishing conversation, to open the link conductors. to-allow the line circuit L of the calling subscriber to restore to normal to permit the subscriber to recall. The relay LD also operates when the calling subscriber replaces his receiver and before the called subscriber answers, and then serves to disconnect the ringing current from the called line when the cord circuit B is used for cstablishing a local connection.

The calling end of the cord circuit l? is provided with a sleeve relay SL actuated when the calling plug Cl? is inserted into a jack of a called local line or into an outgoing trunk jack which extends to a distant exchange. The relay SL, upon cnergization, opens the circuit of the listening relay LS, which relay de-energizes to disconnect the operators set 0 from the cord conductors. A party-line ringing key RK is provided for connecting one of a plurality of ringing generators G, G, G or G to signal the called-for subscriber when the cord circuit is used to establish a local connection. A ringing control relay RC is provided which is actuated upon the actuation of the ringing key BK, and the said relay RC upon actuation brings about the encrgization of the interrupter relay IR, which relay IR is intermittently ener ized and de-cnergizer'l through the agency of an interrupter I to connect ringing current to the called local line. A ringing trip relay RT is provided which is actuated upon the response of the subscriber at the local called-tor substation. A supervisory relay SR is also provided which is actuated upon the response of the called-tor subscriber, either by the response of a locally connected subscriber or a subscriber at a distant exchange. A calling supervisory lamp CL is provided and is used to: the usual supervisory purposes.

In order to handle trunking connections, in addition to the equipment just described, we provide atrunk order wire key Oi? tor each cord circuit, which key when actuated operates a secondary listening relay SLR which connects the operators and also opens the cord conductors. The operators sct O is connected to the calling end of the cord circuit B, whereby the operator at the cord circuit B may converse with the operator to whom the trunk connection is to be extended.

The secondary listening relay SLR. the battery feed and tone disconnect relay ill and tone device ST are common to an operator's position and are brought into association with a trunking connection when the order wire key OlV is actuated. as will be more fully hereinafter described.

Referring now to Fig. 2, we illustrate a trunk ack TJ, oi which there are a nu1nbe bet-ore each operators position, and which are multiply connected to a plurality of finder switches F S whereby any one of plurality of the said switches. ES may seize the connected trunk jack TJ, as willhe more fully hereinafter described. Associated with each trunk jack Til, we show line relay LR and acut-otf relay C D, for purl 5 poses as will be more fully l'iereimiiter do scribed. flhe tinderswitch FS may be of any clcsiredlor suitable construction and is provided with a spring: restored shaft h ving wipers 2, 3, l and 5 and with four sets of fifty contacts 6,7, 8 and 9, to which contacts the trunk jacks TJ are inultipled.

A rotary step-,by-step motor megnet lllM is provided tor rotating the switchlsheftland wipers 2 R lby leans of a ratchet and pawl mechanism. A. retaining pawl is. also pror dedend adopted to be operatedby \arelease relay HM for permitting the. shaft ,wipers 2, 53,14. and 5 to be restored to normal by spring tension. common starting wire S l/V provided and common to a group oftrunh l s TJ which lead toagroup-of switches l A bridging relay is lproridec which energ ze when the; trunk jeclr TJ is SEIZGCi the ch ES to shunt the motor of cit-normal contacts ON which assume theiralternete position upon; the first stop of the switch toil norn'iel, and remain .so until the switch F551 is again restored to nornia The trunking circuit extends to the dis tant exehang over the conductors and 12th which conductors terminate inc tru nlrinn switch 'Firl loceted at the distanthrc ch: L. vh The SWltCll' FF) issiii'iilai to the switch Fflo'li them change M and is pro rided with .a spring restored shaft which cs1 swipers 10,1 1, 12 and 13, and contact sets l-l, l5,-l6 end 17, of which there are fifty sets whichmay be engaged by the said wipers 10, ll, 12 and 13, and to which contiicts the trunk circuit of the exchai'igge N :u-einultipled. The switch F8 is provided. witha line relay LE which is actuated thena switch FS of the exchange ill seizes an outgoing trunk jock T l. l-hl'l'lOtOT magnet iii till is provided,which steps the wipers 1O, 11, 12 and 18 from one set of contacts 14,15, 16 and 17 to the next to seek on idle trunk circuit in a trunk or I operators-positionat the'distent exchange ll. it cut oii relay UU is also-provided whicn. is energized when an idleeetof contacts is seized and a release-magnet BM prov-idedwhich, when energized, permits the release of the switch to=per1nit the wipgerto restore to normal. -A set of oft-normal contacts UN" is prodded, which assume itheii' alternatepositionupon therfirst step net MM. l to prevent further edvancel incnt of the ,xi'ipers 12, '3, e and 5. i The Y relay SH, energizes upon the ectuof the switch wipers oil normal and again restored, to their llOllllEtl position when the wipers sssui'ue their normal position. when the switch is released.

The trunl: circuit C as illustrated in Fig.1. is adopted to be seized by a switch F555? 1 terminates at it. icoininp' end in a rep wring; coil: :11 comprises windings (r. 7;, c artl (l. A test relay T. is provided, which a: '11 ed when the trunk is seized and a relay {m5 ov'itlec which isactuetcrl upon the SllRlQlZzLlTlOll of relay T. An en ergizing circuit is also established for the busy control relay BUR to prepare circuits in the operators busy control and storing circuitsand in the operators eequn-ince eelecting; switch circuit, as will he more I- hereinafter described. A uni; opei listening-relay TL'R is pi V the connection of the trnnlroperators set to the 'Funk conductors and a calling; lamp C UL is also provided which when lighted Ignals the trunk operator that a cell itimiting her attention. A sleeve relay EL provided. which is energized when the nli' plugll? of the trunk circuit C is inrted into the jack of a, called line and a busy guard relay is also provided, which relay GU is energized upon the energization of the relay Elli. A motor relay MR is also provided, wliiich is energized upon the actuation Ojl T to re ster. a connection, and e i cut-oil relay hit) is provided which is eie 'siecl after the meter relay MR causes it alien to prevent further re ions or the rector. A partyno ring! he}? Eli" is: provided, aid asoated therewith or s plurolityof ringing;

,iienerators (RG and G lort-he usual ialing iiurposes. it 1-1 nip; control reswore, A combined disconnect and storing; lamp till provided, as 1s also a ringing:

l illlillj) EL.

Referring now to Fig. l, illustrating three trunk operators busy control and'storingr circuits 7", it and j, ossun ied to be associated with three operators positions F, H and J: Each circuit is ulll'lllill? to the others and descr ption of the circuit j is sufficient. The operatoids' busy control; lCl storing circuit 7 associated with the trunk o1 3eratorsposition F is provided with flour call storing relays Cl-l, CA and CA, which are of the marginal typerin that the relay CAL will operate through 113000 ohm resistance to ground which is placed in circuit with the relay CA upon the energiztion of the relay BER ol a! trunk cord l} i which i is seized to extend a connection to the trunk operators position F. The relay CA will operate through a 1500-ohm resistance to ground, but not through 3000 ohms, relay CA through a 1000-ohm resistance to ground, but not through 1500 ohms, and relay CA. through a 750-ohm resistance to ground, but not through 1000 ohms, for tie purpose of storing calls before this trunk operatoi"s position F, as will be more fully hereinafter described. Busy clearing relays PC, BC EU and B are also provided, which relays, upon energization, establish energizinn; circuits tor the position busyingg relays PB, P13 PB" and PB, respectively, to establish energizing circuits for the group busy relays BU, which relays upon energization busy all. the trunks of the trunk operators position F when a cord has been seized in this operators position.

Referring now to Figs. 5 and 6: ll e illustrate the operators sequence call. selecting switches SCS. SCS, SCS and SCS which are provided four per operator. These switches, when calls are extended to a trunk operators position F, are operated to select the selected trunk circuit to operatively connect therewith. l Vhen calls are stored at a trunk ope 'ators position as F, the switches SCS, etc., are operated and restored in a regular rotation. The switch which is typical of all four switches with which ach operators position is equipped. will be described. It is provided with wipers 18, 19, and 21, which, through the agency of a motor magnet MM are stepped into engagement with the contact sets 22, 2 24: and 25 to select the contacts to which the seized trunk circuit is multipled. A bri i ing relay BG is provided, which when energized connects the operators talking wires to the trunk conductors. A release magnet Rh 2 is also provided, which when energized withdraws its retaining pawl to permit the wipers to restore to no "real under spring: tension. Gil-normal contacts ON are also provided, which assume their alternate position upon the first step of the wipers off normal and are restored to their normal position upon the restoration of the wipers to normal.

In Fig. 7 we illustrate an'operators selecting switch, which comprises wipers 26, 27, 28 and 29, which are stepped from one contact set 80, 31, 32 and 33 to the next through the agency of a motor magnet MM to pick up the calls extended to an operators position in the order in which they are received or stored at an operators position. A bridging relay EG is provided which, when energized, connects the operators set 0 through to the trunk cord conductors. The switch is a fivepoint switch, and when the wipers engage the fifth set of contacts, a release magnet Rl' is energized to release the wipers so that they may again he stepped from one contact set to the next to connect the operators set O to the trunk conductor. A set of oil-normal contacts Oi? are provided, which are moved to their alternate position upon the first step 01 the wipers otl' normal and moved back to their normal position when the wipers are restored to normal.

The system outlined comprises an exchange M, which comprises 3:. and. B switchboards in which the A operators are each provided with a plurality of cord circuits B for interconnecting subscribers lines A. The A operator is also provided with a plurality of trunk jacks ill which extend to a distant exchange. The B operators at the distant erg-change are each provided with a plurality of trunk circuits C, of which there are forty for each trunk position and means are provided so that any 01" the A operators at the @XClliU. M may select an idle B operator and an idle incoming trunk at this B operators position. The operators busy control and storing; circuits 7. h and provide means tor controlling' the busy when the trunk operator's set and trunk are automatically selected in one of these positions. A position remains busy as longas a particular operator has a greater load than any adjacent operator (one in the same group). and the busy is removed whene .'er the operator has a smaller load, or one equal to the smallest load on any operator s position in the same group.

A storing feature is also provided where by as many as "four calls may be stored in front of each trunking" operator. In the trunk circuit C as described in connection with F 3, a disconnect and storing; lamp DSL is lighted when a call is extended to the operators position, and indicates to the trunk operator at all times the number of stored at her position. The switches S055, 868', etc, of which there are four tor each operations position, also operate when calls are connected to an operators position, and when calls are stored the switches SCS, SCS, etc, also operate to store the calls on the tour switches SCS, SSS, etc. in their regular rotation. The operators switch OS, of which there is one for each position. picks up these calls in the sequence in which they are received and stored.

.ecssuming now that the subscriber at the substation A of the exchange M initiates a call, the removal of the receiver thcrea closes an energizing circuit for the line relay LB of the line circuit L, over the line conductors, and the closing of the alternate contact of line relay LR upon energization lights line lamps S at a plurality of operators positions. Assuming; that it is the operator associated with the cord circuit B that answers the call, the insertion of the [ill , sleeve relay SL.

answering plugi-lrl' into tlie jack J Otthe calling); li e establishes aseries energizing; circuit T01 the cut-ol frelay C0 of the line circuit L and the sleevc i'elay Sill oi the cut-oil relay CO to ground. The closure oi" alternate cont-act5 lctthe relay ST closes a circuitthrough the loWresi-stance winding oil the relay ST, thecircnit being traced from battery til {rough the "Winding 50 01 the relay ST, its alternatecontact 5%, over the previously traced path to ground through the Winding; ot the cut-oil relay CO.

lhe l h resistance Winding til oi" the rein ST lSSllLlDtQCl, this arrangement pro cinglor secret service, as relay ST oi second cord Will not operate in series with the cut-otlielay CO tor-the reason that the low winding oi the relay; tBT of the cord circuit l3 renders therelayST of the second cord inoperative;

The closingoitalternate contact establishes an energizingcircnittor the answen ing supervisory relay AS, traced from batterythroughthe-lower winding of the relay AS, normal contact 56 0i the relay LD, rine; contacts of the connected plug AP and jack-ll, through the no'wclosed contacts of th e substation switchhoolc an d buclr thro u gjh the tip contacts of the jack J and plug Al nornia-l contact 5'? oi the relay LD, eondu'ctor 58; alternate contact of relay ST,

conductor through the upper winding of the relay ASto ground. The opening; of

i'ioirnial contact (30 otthe relay ASupon its ener zation prevents'the premature lighting oi the answering siipervlsory lamp, AL. eiierc ization ot the relay CU of the line circuit L opens the energizing circuit of the line relay Till, which relay restores Lice the line signals ti. The closingof alternate contact 61 of there'lay ST cstah' lishes an energizing CllClllllTOl the listening relay traced tronibattery through the Wording: otthc relay LS, conductor 62, alternate contact (51 ol' the relay ST, conductor 63, to ground at norinal contact Gel ot the The 'relay LS energizing; cl ses its alternate contzicts 65 and to connectthe operato11"s sett) to the cord conductors.

Should another operator attempt to seize the call after the operator associated with the cordon-cult connected thereto, the low resistance path through Winding 50 oil the relay ST prevents the relay ST of the secondcordfrom operating, and the listeningg; relay lliSot' the second cord tailing to operate deesnot connect its associated open ato'rs set 0 across the cord conductors. The

second operstor failing to receive a response when she answers, knows that the call has been answered by another operator and With draws the plug oi her cord circuit from the multiple jest: ot' the calling line. The operator s U having been connected to the cord condilictors asjust described, the operator now iii lllGS the wants otthe calling subscriber at the substation'A. The cord circuit B may be used for establishing local connections between the subscribers tenninating at the exchange M and also may be used for trunk connections between :it and distant exchanges;

Assuming thatthe subscriber at the'suhstation A in the exchange M Wishes to converse Witlrtho subscriber at thesubstation l) terminating at the exchange N, the open ator 'nowinserts the calling plug GP into a trunk jack TJ Which leads to the exchange N, andatter into the trunk jack TJ the o erator actuates the trunk order Wire hey Ol l which order wire hey OW is individual tothe' cord circuit. The insertion of the plug Cl? into" trunlr TJ establishes series energizing circuit for the sleeve relay SL of-thecord circ Band the line relay LR" associated with the trunk jack TJ, the circuit being traced from battery throughthe Winding of the sleeve relay SL, conductor 68, sleeve contacts of the connected plus; JP and trunk jack Til, to groundthrough the winding of the line relay IJIZI. Relay Sli now energizes and opens ltSllOl'l'l'lttl contact Gel", thusopcn ing theenergizingr circuit ot the listening relay til; which relay LS restoresto normal, and the opening oi alternate contacts (iii and disconnects the operatorsset Otroln the cord conductors. The closing of alternate contact of the relay SL closes a circuit tor the callingsupervisory lan'ip CL, traced :liron'i battery through the lamp CL, normal contact 70 ot the rii'iging control relay RC, conductors? 1 and 79, normal contact 73 of the linlcdisc-onnect relay LI), con ductor 'l'l, normal contact 75 of theringing trip relay RT, conductor 76, norinalcontact 77' of the supervisory relay SR, conductors 7S andl'tl, to ground at alternate contact 69 01 616 relay UL, the said lamp CL new lightinc; over the circuit just traced, The actu atien oi? the trunk order Wirekey OlVopens the cord conductors otthe callingend oi the cord circuit B at its contacts 80 an'dSl, and the closing oi alternate contactSQ of the order wire he (Ell establishes an energizing circuit tor the secondary listeningrelay Slill, over a circuit traced from battery through the winding oi? relay SLR, conductor 83, to ground atalternate contact 82 of the key, OW. The relay SLR, it is to he understood, is' common to an operators position, and the closure oi? alternate contacts and 85 connects the operators set 0 tothe calling the insertion of the plugCP end of the cord B over conductors 86 and 87, 88 and 89, and through the make-before break contacts 90 and 91 of the key 01V, through the tip and sleeve conductors 01" the cord circuit B. The closure 01 alternate contact 92 of the line relay LR associated with the trunk ack TJ establishes an energizing circuit for the motor magnet MM of the finder switch FS associated with the trunk jack TJ into which the calling plug GP has been inserted. The circuit of the motor magnet MM may be traced from battery, through the resistance 93, through the wind ing of the motor magnet MM, its normal contact 94, conductor 95, normal contact 96 of the oil-normal contacts ON, conductor 97, normal contact 98 of the switching relay SH, conductor SW7, normal contact 100 of the cut-off relay CO, to ground at alternate contact 92 of the line relay LR. Motor magnet MM energizing steps the wipers of the finder switch FE: into engagement with the first set of contacts 6, 7, 8 and 9. Upon the first step of the wipers 2, 3, 4 and 5 from their normal position, the oH-normal contacts ON assume their alternate position, and the opening of normal contact 96 opens the initial energizin circuit of the motor magnet MM, but a sudastitute energizing circuit is again established for the motor magnet HM upon the closure of its normal contact 94:, circuit being traced from battery through the resistance 93, through the winding of the motor magnet MM, its normal contact 94:, alternate contact 96 of oft-normal contacts ON, normal contact 101, conductor 102, to ground at normal contact 103 of the bridging relay BG.

The magnet MM energizing steps the wipers 2, 3, a and 5 into engagement with the next set of contacts 6, 7 8 and 9, and the opening of its contact 94 again allows the relay MM to restore. Upon the closure of contact 94 magnet MM is again energized, and the interruption of its contact 94 causes the said magnet MM to energize and deenergize, thus stepping the wipers 2, 3, 4t and 5 over the contact sets 6, 7, 8 and 9 in search of a selected trunk jack TJ, and when the wiper 2 of the switch FS engages the grounded contact 6 associated with the trunk jack TJ of the selected trunk, a circuit is established for the bridging relay BG traced from ground at alternate contact 104- of the line relay LR, normal contact 105 of the cut-off relay CO, conductor 106, contact 6, wiper 2, conductor 107, normal contact 108 of the switching relay SH, normal contact 109 of the relay 13G, throughthe winding 110 of the relay BG, conductor 111, through the resistance 93 to battery and ground. The low resistance path through the winding 110 of the relay 13G shunts the magnet MM, preventing further actuation of the said magnet, and the closing of the make-before-break contact 112 of the relay BG closes a locking circuit for the relay BG, traced from ground at alternate contact 113 of the line relay Ll", through the winding of the cut-oil relay CO, conductor 11 1, contact 7, wiper 23, conductor 115, through the lower winding 110 of the relay 13G, the alternate contact 112 ot the relay BG, through the upper winding 110 o t relay BG, conductor 111, through the resist ance 93 to battery and ground. The closing of alternate contact 103 of the relay 11G- establishes an energizing circuit for the switching relay SH, traced from battery through the winding of the relay SH, to ground at alternate contact 103 of the relay BC. The closing of alternate contact 117' of the relay SH establishes a locking circuit tor the said relay SH, traced from battery through the winding of the relay SH, its alternate contact 117, to ground at alternate contact 118 of the off-normal contacts ON. The closing of alternate contact 98 of the relay SH now extends the common starting wire SlY through the said alternate contact 98 to the starting wire Sil which wire SW leads to the next switch of the group so that in the event that an operator inserts another plug CP into a trunk jack TJ associated with her position, the next switch of the group will be used to select the trunk jack. The closing of alternate contact 119 ot the secondary listening relay SLR connects the special tone ST to the tertiary winding of the operators induction coil of the set 0, thus giving the operator of the cord circuit B who is extending the trunk connection a tone notifying her that the switch FS is operating to select the elected trunk. The switch FS having selected trunk jack TJ to be used in extending the connection to the distant exchange N, wipers 2, 8, l and 5 are engaging the contacts 6, T, 8 and 9 associated with the trunk jack TJ, and the energization of the relay BG closes its alternate contacts 120 and 121 to close the continuity of the trunk conductors 122 and 123, which now extends the connection to the incoming end at the distant exchange N. The trunk terminates at the distant exchange N in a switch FS, and upon the closure of the alternate contacts 120 and 121 of the relay BG of the switch F8, an energizing circuit is established for the combined battery feed and tone disconnect re lay BR, traced from battery through the winding 12-1t ot the relay BR. conductor 88, alternate contact 91 of th key (NV. ring contacts of the connected plug Cl and trunk jack TJ, the contact 9, wiper 5, alternate contact 121 of the relay BG, normal contact 125 of the cut-off relay C0 of the switch FS, conductor 126, through the winding of the line relay LR of the switch FS, conductor 127, normal contact 12S 01 the relay CO trunk conductor 122, alternate contact 120 of the relay BG, wiper 4, contact 8, the tip ill) loo

eaner? contacts of the connected jaclt TJ and plug (ll through alternate contact 90 on the key (WV. conductor 89 through the winding 129 of the relay BR to around. Belay 31% upon energization opens its nor contact 130,

disconnectin'z the tone Sir from the opera tors set f) or the cord circn't B, notifying her that the trunli: gack 'ld hasheen selected and that the call has been extended to the "distant excl1an;; ;e M. The line relay LE of the switch FE also enfergggizedover the circuit just tr; C811 and closed its alternate contact 13-1, establishing an GIiElglZlHgClICLilt for the control relay CR, traced from loatconductor nailynoi'mal contact 133 Of the motor magnet Mllflynorinal contact134l 01" the oil-normal contacts ON, conductor 135, to ground at alternate contact 131 of the line relay Lll". he relay CB upon energization closes its alternate contact 136, estahliening an energizing circuit for the motor magnet M111 traced from battery through the Wind ing of the magnet MM, alternate contact ot the relay CR, conductor 137, through the Winding oi the slow-acting relay 138, normal. contact 139 of the relay 1 10, conduc' tor 111, normal contact 14:2 01' the cut-off relay we} conductor 1 13. to ground at Wiper 11. The motor magnet MM upon energizatron steps the moors 10 11512 and 13 into engagement with the first set ct contacts 1 1,

15 16 and 1? which lead to a trnnlr circuit in the exchange N. a

The motor magnet MM" noon e tion opens its normal contact to open the energizing circuit or the control relay CR, and the relay CR new de-enei and the opening of its alternate t 1G opens the circuit of the motor niagne" Mi /l. Should the tlrst set oitcontacts on gain-id the Wipers 10,, 11., and 13 lead to a, trnnl that already in use, the private contact 1? nor-x cn ga ed hy the wip r 11 will he grounded d another error circuit is ictor 1113 oil the wiper 11 to the grounded busy Contact 15. The relay CR ene icing closes its alternate contact 136, estahlshing an energizing circuit tor the motor magnet lrfllll to ground at the busy grounded contact 15 over the pre vionsly de'scrihed path, and the motor on net hill l again energizes to step the wipe 1O 11, 1E? and 13 into engagei'nent With the fongh the winding 01 the relay CR;

nextset 0t conta -ts motor magnet M111 1 pc 1's normal contact 121?} a turn opens the circuit of the Mil l at its alternate contact 1 i 1 thus he seen that disc to the ace-sac. ac ot the relay CR and the motor magnet l the wipers 10, 11, 12 and 13 are stepped from one contact set to the next until an idle set encountered. ll hen the wiper 11 engages an ungrounded contact 153, no ener gifting circuit is established "for the i. CR, and the relay CR remain-"i and thus prevents further ac motor magnet lilllll, and the wipe main in engagencnt with this idle V sctl-l, 15, 16 and 17. The relay 11151 Mina energized during; the rrpid" ener tions and de-energieations oi the rol and 1 normal n of the its normal. contact 1 15 is opened to prevent the energization of thecutott relay CUR and when an idle con act set is encormt the relay 138 restores, and the closing 011 its normal contact 145 establishes an enerinn; circuit for the cutoff relay of switch FE, traced from battery tin-on the Winding ot the relay GU conductor 14, 3, normal contact 1417 of the relay normal contact 145 of the relay 138 ground at alto 'nate contact 1418' otthc nori'n 1 contacts ON.

'llhe closing" of alternate contact 1 219 of relay CO establishes an energizing; ircuitfor the relay 1 10, traced from battery through the winding of the relay 1 1) conductor 150, through the alternate contact ot the relay CS conductor 11 to ground at alternatecontact 1 1-8 ojt ot--norinal con tacts ON. The closing o1 alte ate contact: 152 of relay 1 10 establishes lot for itself traced Winning, oi relay 152 conductors 153 alternate contact 1 111 tacts Gill". The in olf the cut-oil relay contact 11-? ot the relay T energizing circuit is e i 0 relay O0 before i ll. 1th its altcri and 51a to i e OlE-llt tor the cut to (leane rih 'd. 'lhr-a the rein i wiper e con- -from i cnt-oll relay CU oneroii aino; its alternate contacts .128 and 12:1 openn the energizing on o'l v t 11116 linerrlny ill and he closure ot' the said con acts now on;- 11(211'155 the trunk conductors and the se ected idle tron ,L C at an a or trunk operator s 13o at the ef ichanggc N. An energizing circuit for the test relay T of the trunk circuitC is now established,

traced from battery through the winding 124 of the relay BR- associat-ecl with the cord B of the exchange M, conductor 88, alternate contact 91 or". the key OlV, ring contacts of the connected plug CP and trunk jack Til, Contact 9, wiper 5, alternate contact 121 of the relay BG, trunl: conductor 123, alternate contact of the relay CO wiper 13, contact 17, the winding 0 of the repeating coil RP, conductor 155, through the low resistance winding 35 ct relay T, conductor 36 normal contact 3? of relay 2'79, conductor 156, through the winding a of the repeating coil R1 contact 16, wiper 12, alternate con tact 128 of the relay CO trunk conductor 122, alternate contact 120 01 the relay BG, wiper contact 8, tip contacts of the con nected aclr TJ and plug P, lternate con tact 90 of the key OW, conductor 89, to ground through the winding 129 or the relay BR. This circuit just traced shunts out the high resistance winding of relay T of trunk cord C, for purposes as will be presently described.

The closing of alternate contact 15? of the relay T establishes an energizing circuit tor the secondary relay traced from battery through the winding of the said relay SS, conductor 158, to ground at alternate contact 157 of the relay T. The closing of alternate contact 159 01 the relay SS establishes a substitute energizing circuit for the cut-off relay C0 of the finder switch FS, Which may be traced from battery through the winding of the relay CO its alternate contact 160, conductor 161, wiper 10, contact 1 1, conductor 162, to ground through alternate Contact 159 of the relay SS, the said relay CO remaining energized until the termination of convers tion. The closing 01 alternate contact 163 of relay SS establishes a circuit for the combined disconnect and storing lamp DSL, traced from battery through the said lamp DSL, normal contact 164 of the sleeve relay S to ground at alternate contact 163 of the relay SS. The closing of alternate contact 165 of the relay SS establishes an energizing circuit for the busy control relay BCR of the seized trunk cord C, traced from battery through the winding of the relay BCR, conductor 167, normal contact 168 01' the relay S32, to ground at alternate contact 165 of the relay The relay BUR energizing closes its alternate contact 170, establishing an energ zing circuit for the call storing relay CA of the trunk operators busy control and storing circuit 7, which circuit is common to this operators position F, with which the trunk circuit C as seized by the switch F8- is associated. The energizing circuit of the relay CA may be traced from ground through the SOOO-ohm resistance 172, alt-ernate contact 170 of the relay BCR, conductor 173, which is common to all relays BCR- of trunk circuits at position 1 through the winding 01" the relay Cali, conductors 17%, 175, normal contact 176 of the busy clearing relay BC, conductors 177, 178, 179, normal contact 180 of the busy clearing relay BC", conductors 181, 182 and 183 lo battery through normal contact 181- of the busy clearing relay BC. The relay CA, upon energizatien, closes its alternate contact 18.1, establishing an energizing circuit for the busy clearing relay BC, traced iroin battery, through the winding of the relay BC, to ground at alternate contact 185 01" the relay CA.

The relay C energizing, closes its alternate contact 186 to establish an energizingcircuit for the position busying relay Pl i, traced from battery through the upper wind ing 18'? of the relay PB to ground at alternate contact 186 of the relay BC. The relay PB energizes over this circuit and closes its alternate contact 188 connecting ground to the conductor 340, which ground operates the group of busying relays BU associated with the position F, and the busying relays BU upon energization close their alternate contacts 18%, temporarily busying the balance of the trunks in this position by grounding their contacts 15 at the selecting switches, each trunk having a wire, as 190. leading to a relay EU. The busy potential thus placed on all the private contacts 15 and their multiples of trunks at this operators position remains until the call which has been extended over this particular trunk to her position is extended to the called line. as will be more fully hereinafter described. The relay BUR upon energization also closes its alternate contacts 191, 19:2. The closing of alternate contact 191 connects ground to the starting conductor SA common to all relays BCR oi the position, to close an energizing circuit for the motor magnet MM oi the cperatofis sequence call selecting switch SCS, of which there are four for each operators position, for purpose. as will be hereinafter more fully dcscril'ied.

The circuit of the motor magnet MB? of the switch SCS may be traced 'lrom battery through the resistance 193, the winding of magnet M31 its normal contact 19-1. normal contacts 195 of the oil-normal contacts OX conductor 1%, normal contact 19? of the relay 19S, starting conductor 811, normal contact 199 of the trunk listening relay TLR, conductor 200, to ground at alternate contact 191 oi the relay BC/llc The magnet liilil upon ei'iergization steps the wipers 18, 19, and 21 into engagement with the first set of contacts 22. 93, '21 and Q5, and upon the first step of the wipers oil-normal, the oil-normal contacts QR assume their alternate position. and the motor magnet MM upon energization opensits normal contact 1% to interrupt its circuit, and the uutgnet' lclM? now restores. The otl nornial contact-s ON having moved to their alternate position, the initial energizing circuit ct magnet l'alrl opened at normal contact 195i ct ell-normal contacts 0153 but the closing of! alternate coatact 195 of oil-normal contactstlhl estahlishes a substitute energizingcircuit for the motor magnet MM traced trombattery through resistance 193, through the winding of the motor magnet Mill its normal con-- tact 194;, alternate contact 1% t cit-normal contact Oh; conduct r- 201, normal contact 202 of relay 198, conductor 203 to ground at normal contact 01'' the bri l in relay The motor magnet M. is again energized over this circuit, aud due to the queuing and closing of its contact 194, it thue alternately enei "used and rte-energized toetep the Wipers lo 19, aud front one set of contacts 22 23, i and fl'to the next, and when the Wiper 18 engag s the contact- 22-, wrich was grounded upon the energization of the ralay BUR of the trunk circuit C, an energizing circuit" is established for the bridging relay ot the switch SGSlfWl'llCll may be traced troin battery through the resistaitice 193, conductor 205, through the upper" Winding 206 oi the relay BG normal contact 207 of relay l conductor Qtlth normal cont ct 2090i} the relay 1'98, conductorQlO, Wiper contact 22, conductor: 211, normal couot the relay Tlllh conductor 2153, out al'ernate contact 192 oil the i The relay 13G upon energizaits alternate contact 214:, closing ug circuit for itselt traced from hot L rough the resistance 193', conductor throughthe upperw it-thug; 266 of the l RG its alternate contact 21%, lower ou lug 215 ottherelay' RG29 conductor 216, w" 39, contact 23, conductor 351, through udi ilug oi? the relay T LE, coucaictor 3 to-ground at alternate contact 5218 oi" 19 relay lGll, andrelay T'lllt is also ened for thepu-rposes as will presently i described;

The circuit just described, which cauaee the euergization of relay RG shunts the mot-or magnet all and prevents further actuations of the said magnet and the Wipers 18, 1 20 and 21 remain inengageiueut with the-selected of contacts 33., 2-4.;

and The relay BU upon once u, tLlOD. c rte: alternate contact 204:, estah islnug uit tor the relzw 198, r A. om h 'ttei "lurough the Wu'idir or the re ay 1%, concuctor 219 to groan at alternate contact 204 of the relay B t-l and the relay 'lttS eaei "Zing; closes ita alternate haw a hoe contact ,1- of the oil-normalcontacts ON. The clonin oitalteruatc comacts and 22.3 of the relay BG established an energlzuig circuit for the hue relay LR", traced troin butte tL-"ouuh the Winding 12a of the re- 7 la ciated With the cord circuit 13, hauqe M, conductor 88', alternate contac 91 of the key ()"W, ring contacts ot the connected plug CP and yack TJ, contact-9, Wiper 5, alternate contact 121 of the relay LEG, trunk conductor 123, alternate contact 1250i the cutoff relay CO Wiper 13, contact 17, conductor 224;, alternate contact of therelay TLR, conductor 5226,

contact 520, wiper 21, alternate contact lo alternate Contact 128 of relay CO trunk conductor 122, alternate contact 120 of the relay 13th Wiper 4-, contact 8, tip contacts or the connected trunk j'aclr and alternate contact oi the key conductor 89 to ground throughthe Wind- 12901" the relay BR. The relay L13?" 'zingcloses itsalternate contact 2230, hing an energizing circuit for the starting: relay 8G traced from battery tl 'h the Winding ol the relay St}, through ground at alternate contact 230 of the relay Llt The relay upon encrp ization closes its alternate contacts 22-31. and 22352, and the closing of alternate contact establishes an energizing; circuit fothe switching relay 1-3? of the operators se cting switch O85 traced from L nd alternate contact 231 of the relay fail; coirductor contact 81, wiper 27; conductor 0 E234 i'iorn'ial Contact J35 of relay 236, normal contact 237' of the relay EG through the low resistance Winding otthe relay 13G; coruluctor 9,89, throughthe resistance 9A0 to :2 tery.

The circuit-just traced through the relay EG shunts the magnet MM of tire switch OS, due to the low resistance paththroiurh Winding oat relay EG and preventa the magnet MM from stepping the Wipers 26 27, 28 and 29 ot the switch. Tlhe relay EG upon euergization opens its normal contact 23'? and a substitute circuit established for the said relay BG, traced tronibattery through the resistance 9A0, conductor 25%).; through the Winding 238 and 2451 ot the re lay 13G, normal contact 235 of the relay 236 to ground at alternate contact-n31 of the re lay SG over the previously described path.

The closing of alternate contacts 242 and 243 of the relay 13G connects the operatofa set 0 to the trunk conductors ol the trunk circuit C, from alternatecontact 24-2 of therelay BIG, the Wiper 28, contact conductor 244', alternate contact 222 of relay BG- wiper 20, contact 24, conductor 227, contact 228 of the relay TLR, conductor 229 to the tip strand of the trunk cord C, and the other lead from the operators set O extends through alternate contact 243 of the relay BG the wiper 29, contact 33, conductor 245, through alternate contact 223 of the relay RG wiper 21, contact 25, conductor 226, alte nate contact 225 of the relay TLR, conductor 224, to the ring strand or" the trunk cord.

-Reterring again to the switch SCS, the energization of relay 198 causes its alternate contact 209 to close, to establish an energizing circuit for the relay 246 of the cord C, traced from battery through the winding of the relay 236 of the switch OS, conductor 247, wiper 26, contact 30, conductor 248, alternate contact 209 of the relay 198, conductor 210, wiper 18, contact 22, conductor 211, alternate contact 212 oi"v the relay TLR to ground through the winding of the relay 246, which relay energizes over this circuit, but relay 236 of the switch OS does not, due to its construction and adjustment. The closing of alternate contact 249 of the relay 246 closes a circuit for the call lamp CAL from battery through the lamp CAL to ground at alternate contact 249 of the relay 246, and the lighting of the lamp CAL notifies the trunk operator of the position F that the call has been extended to her position and is awaiting her attention. The trunk operators set O having been connected to the trunk cord conductors, as just described, through alternate contacts 225 and 228 of relay TLR of the seized trunk cord C, the operator, noting the lighted signal GAL, inquires the number of the substation that is Wanted by the calling subscriber at the exchange d from the operator at the exchange M, and assuming that the operator at the exchange M now passes the number to the trunk or B operator at the exchange N, and that it is the subscriber at the substation D that is wanted, the trunk operator at the e:-: change N will now test the multiple jack J of the wanted substation in the usual manner as to its idle or busy condition.

After the A operator at the exchange M has passed the number of the wanted substation to the B or trunk operator at the exchange N, the A operator restores the key OW. The restoration opens the alternate contact 82 of the said key, thus allowing the secondary listening relay SLR at the exchange M to restore, and the opening of its alternate contacts 84 and 85 disconnects the operators set 0 at the exchange M from the cord conductors. The closing of the makeloefore-break contacts and 91 of the key UW now establishes a substitute energizing circuit for the test relay T of the trunk cord C at the exchange N, traced from ground through the upper winding of the relay of the cord circuit B at the exchange M, alternate contact 40 of the sleeve relay Sli, normal contact 41 of the interrupter relay IR, normal contact 80 ot the key OW, and over the previously described path through the low resistance winding 35 of the relay T, back through normal contact 81 of the key OW, normal contact ot the relay ill, to battery, through the lower winding of the relay SR. The relay SR also energizes over this circuit due to the low resistance path through the winding oi the relay '1 ol the trunk C at the exchange h, and the opening of normal contact 77 of the relay SR of cord B at the exchange M prevents the supcrvisory signal CL from lighting, thus giving the A operator at the exchange M a dark keyshelf.

Assuming that the line is idle, the trunk operator associated with the trunk C inserts the trunk plug Tl into the multiple jack l of the wanted substation i), thus establishing a series energizing circuit for the sleeve relay SL of the trunk circuit C and the cutotl relay C0 of the line circuit L associated with the called line, traced from battery through the winding of the relay SL, con ductor 250, sleeve contacts of the connected plug TP and jack J to ground through the winding of the cut-oil relay C0 The relay SL upon energization opens its normal contact 1(54, interrupting the energizing circuit of the combined disconnect and storing lamp DSL, which lamp is now etlaced. The sleeve relay SL energizing closes its alternate contact 251, establishing an energizing circuit for the busy guard relay GU, traced from battery through the winding 252 oi" relay GU, normal contact of relay GU, conductor 254, alternate contact of relay SS, conductors 256 and 257 to ground at alternate contact 251 of the relay SL. Jr locking circuit is closed through the lower winding 258 of the relay GU, traced from battery through its lower winding 258, its alternate contact 259, conductor 200, to ground at alternate contact 163 of relay SS. A locking circuit is also established through the upper winding 2: 2 of the relay l-l from battery through the winding 252 of the relay GU, its alternate contact 261, conductors 256 and 257 to ground at alternate contact 251 of the relay SL. These two locking circuits for the relay ill are for purposes as will be presently described.

The sleeve relay Sli upon energ cation opens its normal contact 168 to open the energizing circuit through the relay BCR and the relay BCR upon de-energization opens its alternate contact 170. The opening 01 alternate contact 170 oi relay BCR opens the energizing circuit of the relay CA of the trunk operators control and storing circuit associated with this operators position F, of which the trunk circuit C is one. The

1 Moth-v7 relay CA now restores and the opening; oft its alternate contact 185 opens the ing circuit oi the relay BC. he relay BU upon restoration opens its alternate contact l8o,opei1ir1g the error l ai e. circuit ol the relay PB and the relay l 'l l upon de-energization opens its alternate contact 188 re moving the ground from the group of busying relays BU, vhich relays now restore a d the opening of their alternate contacts 18 removes the husying grounds from the inultiple contacts 15 of the switches F8 in whi h the trunk cords C of this trunk opers position. ll terrniuate, making then) again selectable so that other calls may be extended to this B operators position F.

The closing of alternate contact 262 of the relay "GU however, places a busy potential upon the private contact 15 ol: the selected trunk circuit C which may be traced from ground at alternate contact 262 of the relay (ill, conductors 263 and 264, to the contact 15, thus preventing any other switch, as l l l, irozn selecting this particular trunk that now in use. The relay BUR upon resto tion opens its alternate contact 218 to open the energizing circuit of the relay TLR oi the trunk C, and the relay BG oi the switch @953. The relay "TLR upon restoration opens its alternate contact 212, allowing relay 246 to de-energize The relay 246 restoring opens its alternate contact 2 19, to elliace the called signal lanip CAL, and the relay TLR upon restoration also opens its alternate contacts 225 and to disconnect the trunk operators set 0 from the trunk cord conductors. The relay BG upon restoration closes its normal contact 204-, closing; an energizing circuit for the release magnet ltllfi traced from battery through the winding 0'? release magnet HM alternate contact of relay 19S, conductor 203 to around at normal contact 204: of: the now do-en iced relay BGiand the release map; not ll now Withdraws the retai. ing; pawl the ratchet and allows the wipers 18 19 20 and 21 to restore to their normal position.

The relay 270 is also energised upon the restoration ot the relay RG due to the closing oil its normal contact 204:, but the encrn'ization ot this relay has no effect on the circuit at this time. hen the wipers reach their normal position, the Oll-n017llthl001k tacts Uh assume their normal position; and the opening of alternate contact 221 oi the said oil-normal contacts 0N opens the lockinn' circuit 'ot relay 1% and the opening; ol' alternate contact 221 allows relay 198 to re storen and the opening of alternate contact 202 of relay 1.98 opens the circuit of the release magnet RM", and the relay 270, which relay and magnet now restore to normal. l l hen relay 'BG ole-energizes, its alternate contacts 222 and 223 are openedallowing :i J and the relay new restores. The sequence selectii 1 switch. BUS and the operators selecting switches are now at normal and are again ready to select another call that may be extended to T5 the operator"s position F.

Returning now to the extension ot a call totho called subscriber at the suhstati on B, and the energization of the relay (it U the l u at alternate contact fill of the ra- 1 J closesan energizing circuit tor the meter relay lt lliiv traced i i-0rd battery throuph the winding o'lthe meter relay MR nor contact 273 or the meter cutofirelay and conductor-272 to ground at alternate coi ct 2'71 of the relay GU, the said meter relay MR now actuating to register a coiniiection. The closure alternate contactifii'l oil the relay GU also energizes the meter cut-oil relay M0, the circuit being traced from h tery through the winding of the relay 1 to ground atalternate contact 2?]. ot the relay GU. The meter cut oil relay MU upon energiz-ation opens its normal cont i preventing further actuations ot he n c: relay MR, which'ineter relay llllituowr stores to nornaah A circuit tor the ri lan'ip is also established traced ha cry throu 'h the lamp llLgnornial contact 2740f r ay 1C, conductor pnor nial. contact 2%, of the ringing riprelay hl,con.ductor' 277, IlfOlflllHl contact of the relay 279, conductors 250 and 525'? to ground alternate contact SL. The rin ,;ing lainp BL is lighted ore this circuit, giving the trunk operator associated with this trunlr cord C visual indicatiou'notitying her that the called subscriber at he substation D has as not l a nale .B To signal the called t 1' at the substation D the opertci a. with the trunk circuit C now depi proper ringing hey plui r 7 hey 11K to connect the Dl'Uf orator frequency of the reneintoit' G. G. .l" or G as the case may he, to operate the lat the called substation l).

that the i c" hc the ciated with this fire o of ti said l-fc I h. i ll' control relay RC, traced l 0111 ougrh the winding of the said HG conductor 2S1 alternat con'ftc. the end spring contacts of the rii RK, conductor normal contact 278, of lit" is in de-energizcd position, an enerthe relay 279, conductors 256 and 25? to gin circuit tor the supervisory relay SR ground at alternate contact 51ml the sleeve is established, the circuit being traced from relay SL. The closing of alternate contacts 283 of the relay 3C establishes a locking circuit for itself traced through the Winding 01" the sale relay RC its alternate contact 283. condr tor 275. normal contact 276, of the rin trip relay RT, conductor 277, normal contact of relay 2T9, conductors 256 and 25. to ground at alternate contact 251 of the sleeve relay SL. The opening of normal contact 2%- or" the relay RC opens the circuit of the ringing lamp RL and the cloalternate contact 28% of the relay sure or RC energizing circuit for the interru IR traced from battery throu h the 'nding of the relay IR", conduc r 2-85, alternate contact 28% of relay RC. conductor 286, alternate contact 287 oi the r r j conductor 288, anl through the antly rotating interrupter I to ground. The relay is thus intermittently energized and tie-energized by the interrupter I and the ringing current from the generator G is thus connected and disconnected to intermittently operate the called signal at the called for substation D. The ringing current may be traced from the ungrounded pole of the generator G through the closed key plunger contact of the ringing hey Eli conductors 289 and 290, through the winding of the rin ing trip relay RT, conductors 291 and 292, alternate contact 293 of the interrupter relay IR, tip contacts of the connected plug TP and jack J through the condenser and call signal to the called substation 1) back through the ring contacts of the connected jack J and plug TP to battery and ground through alternate contact 294 of the ringing interrupter relay IR. The call signal at the substation D is thus intermittently energized due to the en ergization and de-energization of interrupter relay IR, a. d the subscriber at tne substation D in response to his call signal re- Elhould the subscriber at the substation D remove his receiver d ring a ringing pericch through the winding oi the ringing trip relay 1%--" cu ises the l e to actuate, and the s normal contact 276 opens the locking circuit it RC, which relay RC restores, and the openmg of the alternate contact disconnects interrupter 1 from the interrupter relay and irevents further application of ringing current after the called subscriber at the signal.

Should the subscriber at the substation D moves his receiver from the switchhook.

the combined generator and ba tery flowing opening of it or the ringing control relay Ill, said relay IR now restores to normal substa ion D answers in response to his call remove his receiver during a silent period,

battery through the lower winding of the relay Sit, conductor 295, winding (Z of the repeater coil El normal. contact 2% ol the lug TE and jack J, through the now the substation D, back through the tip 4 ternate contact of the sleeve relay till.

tor 297. through the upper winding oi the regization, establishes an energizing circuit for tact 29E of the relay Slat. conductors 56 and 257 to ground at alternate contact 251 of the sleeve relay SL. Relay 2T9 upon enei ration opens its normal contact 278 it open toe locking circuit oi the ringing control relay BC. In this way, in the event the subscriber the substation D answ rs dur- 1 silent period. the said relay RC, upon in restoration, opens its alternate contact 284. disconnecting nterruptcr l from the ring- 111g interrui iter relay ll? and the said relay IR restoring prevents further application or rn current. A locking circuit for relay 279 is established upon the closure oi its alternate contact 299, traced from battery through the winding of the said rclay 2'79 its alternate contact 299, conductor 30!), normal contact 301 of relay ll l, conductor 302. conductors 356 and 257. to ground at alternate contact 251 of the relay SL. The opening of normal contact 3? of the 10l1l opens tne shunt about the high '1- ance winding 4-5 of the relay T, but the closing of alternate contact 302) of the supervisory rela}- Ell-l pla' another shunt about the high resistance 'ng of the test relay T and the relay oil 0'' the cord circuit B at the exchange 1i remains energized.

The subscriber at the substation A. at the exchange M and the subscriber the substation D at the euclumgc hi are now in conversaional circuit, thc l'tlllilllfl circuit being traced over the heavily nnirlicd conductors.

Assuming now that the subscribers at the substations A and D have finished conversation. they replace their receivers upon their respective switchhooks. The replacing of the receiver by the subscriber at the substation A at the exchange M opens the circuit of the answering sleeve supervisory relay AS ot the cord circuit B, and the closing of its normal contact 60 establishes an energizing circuit for the link disconnect relay Ll), traced nt in that is, when the ringing interrupter relay from battery through the winding of the fill relay Ll),nor1nal contact60 oi: .the'relay AS,

alternate contact 305 of the relay ST, conductor 795 to ground at alternate contact 69 of the sleeve relay fill. The linlr disconnect 5 relay Ll) energizing 'sass crates the calling lino troin the strands oil the cortl circuit at its normal contacts and 57 anti closes a locking circuit for the relay ST extending; from battery hrough the saicl relay, its a ternate contact 5411, conductor 52, alternate contact 58 ot the relay ll-D, alternate contact 805 tl'ie ielay ST, conductor to ground at alternate contact 69 ot the sleeve relay EL. The relays LD anclBT remain eneruntilthe connection is taken down il hejopening of normal contact 53 of the relay LD allows the cut-oit relay C0 of the line circuit L to restore which places the line circuit L at normal. The closing of 1 contact 60 of the relay AS closes a ror the answering supervisory lamp All, traced from battery through the lamp All normal contact 60 of the relay AS, al-

ternate contact 3.05 of the relay ST, con- .tluctor Tl) to ground at alt niate contact 60 or" the relay L. The EtllSWG ing supervisory lamp AL is lighted notii ylup the operator at tie exchange M that the subseriberat the calling substation A has replaced his receiver upon the switchhook. The subscriber at the substation A may immediately initiate a recall before the answering and calling plugs l l and GP are removed by again removing his receiver which again brings about the cnergizaticn ol the line relay LR, Which relay upon energization, closes the circuit for the nniltiple line lanips S, and the same opcrater or another may seize the recall.

The subscriber at the substation D of the exchange it new replaces his receiver upon the switchhoolc opening the energizing circuit of the supervisory relay SE of the trunk circuit C. Upon the restoration or the relay SR, itsalternate contacts 308 is again pencil and as the relay 279 is lockecl up,

nrmnal contact 37 open, and the openinc of the contact 303 of relay SR removes the shunt from about the high resistance winding; ot the relay "l, and the circuit of the s upeii'visory irelay SE of the cord circuit B at the ei-zchange M restores clue to tire insertion of llil'lB high resistance Winding); t5 ot the test relay T into the circuit or the of the cord circuit 13 at the cae M. The relay SRv upon restoration, closes its normal contact 77 to close a 011'- hiio gh the supervisory lamp CLL jliroin w enough the lamp a conductor 306, alternate lconvtact T3 of the relay 'IJD, concluctor i hkuormal cont-act 75 oat the relay hi l, concluctor 7 6,:nor1nal contact 77 otthe relay SR, conductors 78 and ZQt-o ground at alternate contact 69 or the relay SL.

The calling supervisory lamp CL is lightcrl. to notify the operator at the exchange M that the called subscriber at the sulostation I) at the exchange N has replaced his receire The operator at the exchange ht noting the two lighted supervisory signals All and CL ren'iorcs the answering plug All :trointhe jack J otthe calling; line Aianclthe railing plug (JP from thetrunk ack To The lQlnOVfll/(Ili the plug P from the trunk jack opens the energizing circuit of the line relay LR associated with the trunk jack Fri, and the sleeve relay S'L otthe cord cirouit B at the exchange M. The line relay LR now restores and opens its alternate contact 113, openin the series energizing circuitot the cut-oli relay CO, and the relay ll-til of thclincler switch F. The relay .llGr (ls-energizing, closes its normal contact 108, closing an energizing circuit for the release inagnet RM oi the said switch FS, the circuit of the release magnet RM being traced from battery through the winding; of the magnet RM, alternate contact 101 of the relay til-l, conductor 102 to ground at normal contact 103 of the relay BG. The release ct BM, upon energization,removes the retaining pawl from the ratchet, allowing Wipers 2, 8, anal. 5 to restore to their norincl position under spring tension. 'lVhen the Wipers have restorecl'to normal, the oilnorrnal contacts ON are moved to again as sui'nc their normal position, and the opening of alternate contact 1 18 of the otl nor inal contacts ON opens the lockingcircuit of the switch relay SH which relay SH restores to normal, and the opening or alter nate contact 101 of the relay Elli-l opens the circuit of the release magnet RM, Which magnet RM also restores. The finder switch FS isnow at normal and is available for tending other trunk connections.

The :IGHIOVttl of the plug (ll from the trunlr jack T2} at the outgoing curl of the exchange M opens the circuit of the high resistance test relay T ot the trunl-z circuit C, at the exchange N. and the relay T clecnern iizing; opens its alternate contact '15? Which hrin s about the restoration 0 the relay the relay Si.) upon cle-ene tion opens its alternate contact 113 opens the locking circuit through the lower whirling); 258 of the relay GU, but the relay GU cloes not restore this time tlue to the locking circuit through the upper Winding of. the relay (ill, to ground at alternate contact 251 oi the sleeve relay till. The closure oit norinal contact 103 of the relay Sh, cstahlisl'ies a circuit for the coinbinerl disconnect and stori lamp signal Dill, traced. from battery through the lamp DEL, alternate contactlGl-bl relay EL to grountl at norn'ialcontact .103 of the relay SS. The lamp Dir-ill is lighted over this circuit "and notifies the operator at the exchange N that disconnection has taken-place atthe exchange where the call originated, The

Images