US1664665A - Telephone system - Google Patents

Description

April 3, 1928., 6

. H. D. cURRxER ET A1.

TELEPHONE SYSTEM 3 Sheets-$heet 1 April 3, 1928. 1,664,665

H. D. CURRIER E1' AL.

TELEPHONE SYSTEM $5V Sheets-Sheet 2 Original Filed Sent. @41920:

pc f /9/ 192 April 3, 192s.,

H, D. gunmen ET m. TELEHONE SYSTEM 5 Smets-Sheet 3 Patented Apr. 3, 1928.

entran si..

y 1,664,655 carena OFFICE..

HIRAM D. CURRIER AND WILLIAM G. SKULL, 0F CHICAGO, ILLINOIS,v ASSIGNORS TO i KELLOGG- SW'ITCHBOARD AND SUPPLY COMPANY, OF'CI-IICAGO, ILLINOIS, A COR- PORATION 0F ILLINOIS.

TELEPHONE SYSTEM.

Original application filed September 18, 1920, Serial No. 411,289. Divided and this application filed March 9, 1925.

Our invention relates to telephone systems and has to do more particularly with trunk circuits for use with private branch exchange systems in which the trunk circuits are used between local private branch exchange substations and manual exchanges or automatic exchanges.

A feature oi our invention is the provision of means whereby the private branch exchange operator may, by the use of a calling device, dial from her position and actuate the apparatus at the automatic exchange to select the wanted called line without thev plug of the trunk circuit being in a local f line jack.

Another feature of our invention is that the operator may actuate the central office exchange switches with the plug of the trunk inserted in a local subscribers line jack, either when the local subscriber has his receiver on or ofi the switchhook.

A further feature of our invention is the provision of means whereby the instant the private branch exchange subscriber replaces his receiver uponthe switchhoolr, means are actuated in the trunk circuit to clear the line through to the main exchange, so that,

should the private branch subscriber again remove his receiver before the trunk plug is removed from the local jack, the trunk will `again be seized and extend the connection through to the main exchange, and in the event that the private branch exchange substation is equipped with a calling device, the

subscriber may again actuate the automaticV apparatus to seize another called line as wanted. In the event that the trunk circuit was used to extend a connection to a main manual exchange, when the private branch exchange subscriber removes his receiver the trunk is again extended to the said main exchange and the main exchange operator signaled.

Another feature ot our invention is the provision of means so that after the private branch exchange subscriber hangs up and clears the trunk to the main exchange, should :mother call be extended from the main exchange to the branch exchange beforethe plug is taken down. the call lamp of the trunk circuit will be operated, but not the bell otl the private branch exchange subfscriber. f

Serial No. 13,983.

The above features, as well as others of our invention, will be more particularly pointed out in the ensuing specification and appended claims.

This application is af divisional application of our application L111,289, filed September 18, 1920, and issued April 7, 1925, as U. S. Patent No. 1,532,652.

For a better understanding of our invention, reference may be had to the accompanying drawings, in which Fig. 1 illustrates one embodiment of our invention as applied thereto;

Fig.V 2 illustrates another embodiment of our invention; and

Fig. 3 illustrates an automatic exchange system adapted to operate in connection with vour invention.

Referring now more in general to our invention as illustrated in Fig. 1, we show a calling substation A terminating at the main exchange M in a line circuit B, comprising the usual line relay LR, cut-off relay GO, line signal L and the multiple jacks J.

The` cord circuit C located at the main exchange M is shown for use in extending connections from the line circuit B and comprises an answering plug AP and a. calling plug Cllthe two plugs AP and CP being connected by the heavily marked conductors, the said conductors having the condensers K Vand K interposed therein. Associated with the answering end ofthe cord circuit C is the answering tip supervisory relay AT and an answering sleeve supervisory krela-y AS, the two relays controlling the answering supervisory lamp AL. Associated with the calling end of the cord circuit C is a calling tip supervisory relay CT and a calling sleeve supervisory relay CS, the two relays contr-olling the callingr supervisory lamp v operators position, andwvliich are terminals Voftrunk circuits PC. The trunk circuits PC extend to a private branch exchange Switch- Y board 53B, and the said jacks'llJV areV con- Lnected .to the saidl trunk circuits PC, which terminate at the private branch exchange PB over the heavilyinarked conductorsl 32 and 42.

l Thepriva-te branch exchange trunk PC ,is

provided with a kring-up vrelay RU, ivhich l `:reilen/fH-'Jeijates*when ringing current isgappliedV troni adistant exchange. VThe ring-up f relay Ruppert energizatioii, brings about thelightingfof .the line lainp LL, to notify A, the .operator at the-private. branch exchange that" a callv awaits her. attention. A

'.,list-enignglkeyLl is provided which, vwhen actuated, connectstheoperators set O to l the. trunlconductors for the usual purposes.

A V,conibiified `disconnect and guard relay VDS is Valso providedv ,which 1S energized uponl the Iactuation of the listening key LK to .p nal when the operator answers the-call. A sleeve relay SL is'also` provided,`ivhich bring about the eiiacenient ofthe line sig- ;telay is energized when ,the operator inserts the trunlrplug ,TPinto the local line .'jack J ofi the Wanted station at the private ,brancllrexchange A ringing key RK is also, providedgwhich when. actuated, con-U y `nects ringing generator G tol signal the labout the effacement of the holding lampl 40 IHL `disconnects the holding` coil.

calledffor station 4at ,the private branch er:-

change `.Asnpervisory relay 'SR is also provided `which is energized when the party at. thecalled private branch exchange substation answers. A holding relay 49 is also provided, which energizes upon the energization` oi the 'supervisery relay SR to bring acros'sthetrunl; conductors, the said, holding coil `being -,bridged across `Vthe trunlnconductors upon, the energization of the. relay DS. A disconnectsignal DSL-is also-.provided for tlieusiial disconnect signaling purposes. vAn, operators disconnect -relay`-92r and a trunk `cut-off relay CORY are providedand are brought intooperation in Yconnection with the .trunk -circuit 13C-When 50 M the: private branchexchange ,operator O is .,eztendingya connection :troni the-local priyate branch exchangesubstation to an autoaut'oinatic exchange.

irnatic `nain exchange. A calling ldevice. GD isalso provided `Whichis used' by the oper- Kater in .extending a connection toa nia-in Aalso `pfioyided for the-usual purposes..r To

` trunllg PC We show aflocal ,private branch @schaarse .siibstetienfl terminating there# Y in the; tack JT', line. relay. LEZ and 'a line] ktiti the right of the private branch'eiichange signall/v.l A Y i "2 vvehillustrate a modified forni of V trunk-circuit Vin yvhich,A upon 4the energization oa rela of the trunk circuit PC after IA, night -jack NJ isV the Vbranch exchangesubscriber replaces his receiver and Wishes to recall, the removal of the receiver brings about'the lighting of the vline lanip to notify the `operator that the localsubscriber Wishes to recall. The trunk circuit PC is provided with apparatus siniilar to lthat mentioned in connection With the trunk circuit PC oflilig. l.

Having described in general the apparatus Which embodies our invention, We Will now describe nioreuin detail. the operation ofthe systein vas illustrated.

Assuming ,now that the subscriber at the substation A at the .inain exchange initiates Aa, call, the removal of the receiver at the substation closes an energizing. circ-uit for line` relay LR' of the subscribers associated line circuit B, and thesaid relay LR', upon energization7 closesl its alternate contact, esta-blishing a circuit through the line lainp L, `which larnpLis now lighted. The operator plug .AP and, jack J 'to ground Vthrough theV Winding-of the cut-ofi' relay C0. `Therelay C() iiirionenergization opens the energizinglv circuit of theline relay LR, which relay LR now restores and'effaces the line signal L. flhe answering tip supervisory relay AT Y also energized over the line to prevent the premature lighting` of. the `anrnvering supervisoiylainpfAL. The operator of the cord circuit C now actuates herV listening key LK .to connect lier operators set Oto the cord conductors and inquires thc Wants ot the calling subscriber at the substation A.

Assuming that it is the subscriber Flocated at the private branch exchange PB .that is desired, the `operator now inserts the calling plug CP ,into a trunk jack TJ leadingto the private branch exchange P B at which the subscriber F is located. The insertionrof the. said plug CP into the jack TJ establishesan energizing circuit for the 'calling sleeve supervisory relay CS, and the cut-offA relay CO', troni battery through the windiiigof the relay CS, norinal Contact of theifinging key RK, sleeve contacts of the Vconnected Vplug and trunk jack HIJ,

through the `Winding of the Vrelay CO to ground. `The closingof alternate-contact 30of the ,relay CS closes a circuit for the calling,supervisory lamp CL frein battery,

through the Winding of the said lampjCL,

alternate contact 30, normal coiitactglv of the calling tip supervisory relay CT to ground, the lamp CL remaining-lighted unlise incassa 8 til the private branch exchange operator an swers the call, at which time the calling tip supervisory4 relay CT energizes to ei'i'a'ce the supervisory signal CL. The operator at the main exchange now operates the ringing key RK to connect ringing generator Gr to the trunk circuit. Ringing current is thus ex tended over the trunk conductors, which circuit may be traced 'from the ungroundcd pole of the generator G,\tip contacts ot the connected plug Cl? and trunk jack TJ, trunk conductor 32, normal contact 33 of the night ack NJ, normal contact 34 of the dialing relay COR, conductor 35, condenser 36, through the winding ot the ring-up relay RU, conductor 37, normal Contact 3S oit the disconnect relay DS, conductor 89, normal contact 40 of the dial relay COR, norlnal contact 4l of the night jack NJ', trunk conductor 42, sleeve contacts ot the connected trunk jack TJ ot' the plug CP to battery and ground at the alternate contact of the ringing key RK.

The closing ot alternate contact 43 ot the relay RU closes an energizing circuit ot the line lamp LL from battery through the lamp LL, to the grounded alternate contact 43 et relay RU. The operator noting the lighted line lamp LL now actuates her listening key LK. The closure ot alternate contact 44 ot .listening key LK establishes an energizing circuit for the disconnect relay DS, traced from battery through the upper Winding of the relay DS, conductors 45, 46, alternate contact 44 of listening key LK', conductor 47, normal contact 48y of relay 49, conductor 50 to ground at normal contact 5l of the ringing key BK. The closing of alternate contact 44 ot key LK establishes a circuit for the holding lamp HL, traced from battery through the said lamp HL, closed contact 44' ot key LK', conductor 47, normal contact 4S ott relay 49, conductor 50 to.

ground at normal contact 5l ot ringing key RK. It the call proceeds no further than the operator, the circuit is cleared by the operator at the branch exchange actuating the ringing key RK, Which opens the circuit of relay DS and allows it to restore to normal. The relay DS upon energizing unlatches the alternate contact 430i the relay RU, allowing it to restore to el'ace the line signal LL. The relay DS new closes a locking circuit for itself trom battery through. its upper Winding, its alternate contact 52, conductors 5S and 47, normal Contact 48 ot i relay 49, conductor. 50, to ground at normal contact 51 of the ringing key RK.

The closing of alternate contact 38 of the relay DS bridges the holding coil HC across A the trunk conductors trom the point 55, over conductor 85, through the Winding ot' the holding coil HC, normal contact 56 or' the relay 49, conductor 57, alternate contact 38 of relay DS, conductor 39 to the point 58.

lWhen the holding coil HC is thus bridged across the trunk conductors, the relay `GT ot the. cord circuit C at the main exchange operates to openfits normal contact 3,1, thus opening the circuit ot the calling super! visory lamp CL, to thus elace the said lamp CL and notify the operator at the main exchange that the operator has an@ Assuming that it 1s the` lay DS, conductor 61, the sleeve of the plug TP to ground at the sleeve ot the jack J The relay SL upon energization closes its alternate contacts 62 and 63, thereby closing the trunk conductors through to the called substation. The closing of alternate Vcontact 64 of the sleeve relay SL multiplies the ground trom the sleeve ot the jack J to the relay DS, this multiple ground connection to the relay DS being traced from battery through the upper Winding of the relay DS, conductors 45,46 and 65, alternate contact 64 ot relay SL, conductor 66normal contact 67 ot relay 49, conductorV 6l, through the sleeve of the trunk plug TP to ground at the sleeve ot the jack J for purposes as will be presently described. The ground from the sleeve ot' the jack J also extends to the holding lamp HL, traced jtrom battery through the lamp HL, conductors 46 and 65, alternate contact 64 of relay SL,

conductor 66, normal contact 67 ot' relay 49,

conductor 6l, sleeve ot the plug TP to ground at the sleeve ot the jack J', the said lamp HL remaining lighted until the subscriber F answers;

The operator now actuates the rin-ging key RK to connect generator G to signal the called-:tor station F, the ringing circuit being traced from the ungrounded pole ot the generator Gr, tip contacts of the plug TP and the jack J', through the condenser and call hell ot the called station F, the ring contacts ot' the jack J and plug TP, through the alternate Contact of the ringing key RK `to battery and ground..

The opening ot normal contact 5l of the ringing key RK opens the locking circuit ot the relay DS.` but duc to the tact that the ground :troni the sleeve of the jack J is also n'iultipled through the upper winding` of the relay DS, 'as'just described, the relay remains energized during the time that the ringing key is actuated. The party at the station F, in response to hisicall signal, ren'ioves his receiver from the syvitchhook, bringing about the energization of the supervisory relaySR. The Circuit for relay SR extendsover the called line F.

closing of alternate contact 7 0 of the e supervisory. relay SR establishes an energizing ,eircuit for the rela-y 49, traced from battery through the upper Winding of the relay 49, eenduct'or 71, through the lower Winding .ofthe relay DS, conductor 72, alternate con- .ftact 70 of therelay SR, conductor 61,

through the sleeve contact of the trunk plug TP to .ground at the sleeve of the jack JC Y The opening of normal contacts 48 and v6.7 @of the relay.49 opens the locking circuit through the upper Winding of the relay DS, but the series energizing circuit through theuppervvinding of relay 49 and the loiver Winding of relayDS permits the continued energiziation of the said relay DS. The opening of normal. contact 56 of the relay .49 also removes the holding coil HC from kacross the trunk conductors. The closing of alternate contact V67 of `the relay 49 estab- `lishes a locking circuit for relay 49 from battery,@through vthe resistance 75 and the Vjlovver Winding of the relay 49, alternate contact 67 of the4 relay 49, conductor 6l, through 'the sleeve ofthe trunk plug TP to ground jat the sleeve ofthe jack J. The opening of i ynormal contact 67 of relay 49 opens the energizing circuit of lamp HL, which vis novv effaced,"and notifies the operator at the private branch exchange PB that the party at the private branchsubstation Fhas answered. The subscriber at the main ex-v change andthe par-ty at station F ofthe L Aprivate branch exchange are now in conversational circuiti'V The said talking circuit f may be traced over the heavily marked conductors Assuming' that the subscriber at substation A and the party at the private branch exl change station F have finished conversation,

the restoration of the receiver at the station F ofthe private branch exchange opens the" energizing circuit of the supervisory relay SR, and the opening of alternate contact i [of the said relay SR interrupts the ground Y connection from the sleeve of the jack J',

.and the relay DS thus restores to normal.

v'The relay DS upon de-energization opens its alternate contact-60,'Which opens the enerj gizing circuit of the sleeveerelay SL, which relay restores. The openingof its alternate contacts 62 and 63 interrupts the trunk conductors.y The closing of its normal contacts `76 and 77 places the'local private branch exchange battery upon the trunk conductors, extending to the substation.

The closing. of normal contact YOothe sleeve relay SR` novv closes Van energizing circuit A for the disconnect signalk DSL,`

i .y traced fro'rnbattery through thelament of contacti78 of the relay 49, conductor 79,` l ce normal lcontact'7() of the relay SR, conducthe said disconnect signal'v DSL, alternate tor 61, through the sleeve of the trunk plug TP to ground at the sleeve of the'jack J. Thedisconnect signal lighting `notifies the private branch exchange operatorfthat the subscriber has replaced his receiver upon the switchhook.

The relay 49 remaining energized to Iground at the sleeve of the iaclrJ `through .its locking contact 67, prevents the holding main exchange substation A replacing hisV receiver, opens the circuit through thev answering tip supervisory relay AT, which relay [upon lrestoration closesv a circuit through the answering supervisory lamp AL, which lamp AL is lighted toV- notiy the operator that the subscriber atsubs'tation A hasreplaced his receiver.` The operator at the main exchange noting the` two lighted signals'AL and CL now withdraws they an' swering plug AP and calling plug CP4 from the respective jacks J and TJ to ,openithe circuits ot relays AS and GS of thefcord circuit C, which relays AS and GS upon deenergization eiface the supervisory signals AL and CL. Relays CO and CO also restore, thus placing the Vapparatus at the main exchange in. condition for use in'establishing other connections. The private branch exchange operator at PC, noting the lighted .disconnect signal DSL, withdraws the trunk plug TP fromV the jack J', Which-,opens the .locking circuit of the 'relay 49. The relay 49 upon deenergization restores and opens its alternate contact 7 8 to eii'ace the disconnect signal The private branch exchange trunk circuit PT is now at normal and available for use in establishing other connec tions. v

, Assuming now that the subscribers-have replaced their respect-ive receivers upon their respective sivitchhoolrs and that the partyat the private branch exchange substation F 'again removes his receiver before the trunk plug TP has been removed from the jack l',

this removal of the receiver brings about the energization of supervisoryr relay SR. traced `from battery through normal Contact 77 ofV sleeve relay SLV through the `Winding of said relay SR, ring contacts of the connected plug TP and' jaclrJ throughV the closed contacts of the substation switclihook,1baclr; through the tip contacts of the connectedfplug TP andjaclr J ,to ground katnormal Contact 7 6 ot' relay SL. Therelay SR upon energiza-` tion closes 'its alternatecon-tact70, Vestablish'- ingan energizingcircuit for the relay DS,

traced from battery throughl the upper winding ot relay 49, conductor 71 through the lower winding otrelay DS, conductor 72, al-

ternate contact 70 ot relay SR, conductor 61, y

nate contact ot relay DS, conductor 61,v

sleeve contact ot' t-h-e plug TP to ground at the sleeve of the jack J The relay SL upon energization closes its alternate contacts 62 and 63 and thus extends the station F at the private branch exchange PB to main exchange, the main exchange battery thus holding the relay SR energized. The line relay LR at the main exchange will now operate, providing the plug CP has been Withdrawn from kthe jack, over a circuit traced from battery through the winding ot relay LR, normal contact 80 ot relay CO', conductor 32, normal contacts 33 and 34, alternate con` tact G2 of relay SL, tip contacts ot' the plug TP and jack J, through the closed contacts of the substation F, ring` contacts of the jack J and plug TP, through the winding otrelay SR, alternate contact (i3 of relay SL, normal contacts 40 and 41, conductor 42, to ground at normal contact 81 of relay GO. The line relay LR upon energization closes its alternate contact to light 'the trunk signal TS, whichnotiiies the operator atrthe main exchange that a private branch ex change station is calling. The relay SR upon energization also opens the circuit ot' the disconnect signal DSL, which also gives the private branch exchange operator an indication that the party at the station F has called. rlhe closing oi' contact 300 of key LK when the operator, for any reason, actuates the key LK while the plug TP is in jack J', after the subscribers have replaced their receivers, operates to shunt out relay 49, thereby deenergizing the same.

Assuming that the subscribers have replaced their receivers and the operator at the main exchange desires to extend another call to the branch exchange before the plug TP is taken down, the main exchange/operator applies ringing current to the trunk circuit and operates the relay RU as before described, causing the lamp` LL to glow,thus notifying the private branch exchange operator that another call is being extended to the branch exchange.` The operator yagain operates her listening lrey and completes the connection. rPhe ringing current applied to the trunk circuit by the main exchange operator did not reach the substation F even though the plug TP .was in the jack J, 'for the reason that the trunk circuit was open at contacts 62 and G53 ot relay SL.

The branch exchange operator may ex-` tend a,- connection to the main exchange by operating her listening lrey, even though the trunk plug TP 1s not 1n a jack.

Assuming now that a call is extended from y an automatic exchahge as illustrated in Fig. 3 to the private branch exchange PB, the ringing current which is applied from the autoc matic exchange extends over the trunk conductors 32 and 42 and operates the ring-up relay RU ot the branch exchange trunk PC which was seized by the connector of the automatic exchange. The relay RU upon energizing closes its alternate contact 43 to light the lamp LL and the operator at the branch exe change PB in response to the signal actuates her listening key LK. The actuation of the key LK closes a circuit Jfor relay DS and the all closing of its alternate contact 38 bridges the Y holding cord HC across the trunk conductors to operate ringing control means at the main automatic exchange to disconnect ringing current from the trunk circuit. The operation oi' the trunk circuit PC is the same as that described in connection with a manual connection as just described.

VVhenthe trunk circuit is used in connection with a main automatic exchange, it may terminate at the main automatic exchange in a line switch ot the usual type and in the banks of rotary connectors or straight line connectors such as is described and illustrated in the U. S. Patent No. 1,194,741, issued August 15, 1916, to Harry H. 1de. In this case ther conductors 32 and 42 leading to Vthe main exchange will not be included in the apparatus, the trunlr circuit being connected directly to the conductors leading to the automatic exchange, and, therefore, the operation of the trunk circuit at the branch exchange will not atleet the apparatus at the manual main exchange.

The operation of the trunk PC when a private branch station calls a main exchange subscriber of an automatic exchange, is as follows: Assuming now that the operator at the private branch exchange PG wishes to extend a connection to a subscriber at an automatic exchange, she actuates her listening key LK', which closes a circuit for the disconnect relay DS, .traced from battery through the upper winding of the relay DS, conductors 45 and 46, alternate contact 44 of the listening key LK', conductor 47, normal contact 48 ot relay 49, conductor `50 to ground at normal contact 51 of the ringing lrey RK. The closing of alternate Contact 38, upon the energization of DS, bridges the holding coil HC across the trunk conductors, as previously described, thus operating a switch to connect the trunk to either a selector switch or a connector switch, depending upon the size of the exchange. The operator Emi now operates her calling Vdevice .CD to send the required number of impulses to operate Referring now to Fig. 2, weillustrate a modiied `:form ot our invention whereby when the subscriber at the substation F of the private branch exchange replaces his receiver, the energizing of a relay brings about instantaneous disconnection. When the subscriber of the private branch exchange substation F' recalls before the plug TP' is Withdrawn from the local jack J 2, hek

is immediately enabled to signal the operator. It is understood that the trunk PG terminates at the main exchange in equipment similar to that shown in Fig. 1, in which the trunk PC terminates. Assuming now that the call is extended to the private branch exchange PB', the ringing current from the main exchange extends over the trunk conductors, through rnormal contact 150 of the relay COR', conductor 151, through the winding of said relay RU', normal contact 152 of relay DS', conductor 153, normal contact'154 ot relay COR', there back to the main exchange. Relay RU' upon energization closes its alternate contact 155, which closes an energizing circuitlor the line lamp LL of the private branch exchange trunk PC', from ground through alternate contact 155 ot relay RU', conductor 156, through the lamp LL to battery.

.The operator at the private branch ex-` change circuit PC noting the lighted line signal LL', now actuates her listening key LK2 to connect her opera-tors set O2 to the trunk conductors. The closing of alternate contact 157 of the listening key LK2 closes an energizing circuit for the relay DS', traced from battery through the lower winding of the relay DS', conductor 156,A alternate contact 157 of the listening key LK2, conductor 159, normal contact 166 of the re,- lay 161, conducto-r 162 to ground at normal contact 168 of the ringing key BKZ. The closure of alternate contact 152 of the relay DS' bridges the holding coil HC across the trunk conductors for purposes as previously described in connection with Fig. 1. The closing of alternate contact 164 of the relay DSf closes the locking circuit Jfor the relay DS', traced from battery winding of the said relay DS', alternate contact 164,'normal Contact 160 of the relay 161, conductor 162 to ground at normal con tact` 163 of the ringing key RK2. The relay DS upon energization unlatches the con tact 155, which is in its alternate position, allowing the said contact to restore and efface the line signal LL. The operator ot the private branch exchange PB', having been informed that it is'the party at the substation F that is wanted, now inserts the trunk plug TP into the jack J2 ot the local line. Upon the insertion ot the trunk plug TP' into the` jack J2, permanent ground upon the sleeve of the jack J 2 now,l ext-ends oiE the relay from lrelay DS', but

through the upper 'lower windingfot the relay DS to battery.

through the lower winding of holds the said relay DS eneris actuated.

This ground the relay DS gized when the ringing key BKZ An energizing circuit for the holding signal HL is also closed, the circuit being i traced from battery through the holding signal HL', conductor 158, normal contact 166 161, conductor 165, the sleeve ot the trunk plug TP', to ground at the sleeve of the jack J2, the said lamp HL' remaining lighteduntil the subscriber at the local station F' answers. The ringing key` Rh@ is now actuated to send ringing current to the called local station F', ringing current being traced from the ungro-unded pole ot the generator G2, alternate contact of the' ringing key Rl?, tip contacts ot the connected plug TP' and jack J2, through the' condenser and call bell of the substation F, the ring contacts or the jack J2 and plug TP', to battery and ground through the alternate contact ot' the ringing key RK2. The ringing key Rl@ upon actuation has its normal contact 163 opened, opening the initial enegizing circuit ot' relay DS extending through thejupper Winding of the y as the ground Afrom the sleeve ot the jack J2 is now extended through the lower winding 01:' the said relay DS', the said relay is held energized when the ringing kkey RK2 is actuated.

T he subscriber, in response to his call signal, removes his receiver'from the switch.- hook, and the closing 'of the switchliook contacts permits the energizing ot' the super-` visory relay SR', the said currentiior energizing said supervisory relay SR being ted from the main exchange battery. The closing o'r' alternate contact 170 of the supervisory relay SR' closes an energizing circuit tor the relay 161, traced from battery through the upper winding olf the said relay 161, conductor 171, alternate contact 17() of the ref lay Slt', conductors 172 and 165, the sleeve of the plug TP', to ground at the sleeve ot the jack J2. The relay 161 upon energization closes its alternate contact 166, es-

tablishing a locking circuit tor the said ref.

lay, traced from battery, tln'ough the winding ot the said relay. its alternate contact 166, conductor 165, the sleeve ot the plug TP'. to ground at the sleeve ot the jack J2. The closing o1 alternatevcontact 176 ot the relay SR' also closes the holding circuit for the relay DS', traced from battery through the upper winding of the said relay. conductor 171, alternate contact `170 ci re lay SR', conductors 17 2 and 165, the sleeve ot the trunk plug TP' to ground at the sleeve oit the jack J2. tact 166 ot Athe relay`161 brings about the BTS Y l 1,664,665

eiraoiaeneof the hcliifaig` Sign-sinn, which l'elayfSR establishes anenergizing circuit for the disconnect signalf'DSL from battery Y .through the lamp DSU, conductor 1'?" 5, al-

tel-nate contact 176 of relay 161, conductor 177,normaljconta`ct .1750 of relayl SR', con-1l ductors 172,165, the sleeve of the plug TP to ,ground-,attire sieeveof-the jack J?. Thevv clos-ing'fofnrmal contact 170 of relay SR `also establishes an energizing circuit for the .disconnect relay ISR, traced' from battery through-the Winding of the said relay DR, conductor 175, alternate contact 176 ot lthe relay 161,'conductor 177, normal contactlO, conductors V172 and 165, the sleeve of the trln'ilv plug TP to ground at the sleeve v'Ilierelay DRn-pon; energizing opens its normal contactsY 180,181, opening the continuity` of the trunkcond-uctors, and should the subscriber at the private Vbranch exchangeF reca'l-h-theremoval of his receiver from the' "switchho'okl brings aboutithe enegization of thesu'pervisory recall relay SE,

traced from battery through the lower Wind-v.

ing ofthe saidV relay SE, alternate contact 181 of relay'DR,`theringV contacts kof the connected plugY TP andjackzJz, through the closed contacts of the svvitchhook at thesta-` tion' F, back through the tip Vcontacts of the connected plug'TP and jack J2, throughn alternate vcontact 180 of relay DR, to ground through the upper Winding of the said relay vSE..r The rela-y SE uponenergizationcrloses its alternate contact1-82, which againlightsj thef line 'lamp LL, toground' at alternate contact 182` of relay SE, notifying the oper ator at the private branchy exchange trunk PC that the substation F. is recalling. The operatornovv actuate's her 'listening key LK2 to connect her operators set'OZfto thet-runlr conductors,y andv to vextend-the connection to the main exchangershe novv withdraws theV trunk plug TP from the jack J2,1-\vlii.ch

`Withdrfwval opens the loic-king circuit ofthe relay 161, which allows the said relay 'torestoreto normal. lThe closi-nnof normal Contact 160 of the relay 161 again closes air energizing circuit for relayDS" over apath as previously described. Y' `Relay 161 uponV deenergization-ailso opens the energizing` cir-V cuit ofthe relay DR atits alternate contact 176:A The-relay DR *uponV 'deenergization' opens its alternate`contacts'180 and 181, allowing the said supervisory recall relay is readily SE to restore, and .the openingof its alternate contact 182 etl'ace's the line LL. The operator new' again' ,inserts` the"A trunk plug- TP into the jack J bringin'fb'` about the energization of the supervisoryre lay SR and the relay 161, as previouslyfjY` described. The closing ot normal contacts 180. and 181 of the relay DR now closesth continuity el the trunk conductors and ezfi tends the said private branch e'Xcl'i-ange sub1 station F to'fthe main' exchange, andthe operation of the circuit from this pointon.`

scriptiori'.` I Should, the operator Wish to entend a apparent fromY the previous del connection to amain` automatic exchange", f

she actuatesh'er listeningiley LK?, and' they closure of alternate contact 185 lof the riiig u ing` key LK2 extends 'groundl to' contacts 186 and 187L of theY Shun-t Springs ofthe @211;1iiig11 device CD. The shunt springs 4186 I8l are closed, extending thegroundirorial# 'u ternate Contact 185V to the listening key through thenovv closed contacts`j186 and 187,;

overy conductor 188, througlfthe Winding" of the trunk cut-oli relay COR to batteryif The closing oi alternate contacts 189 and `190 of Vthe relayV COR W connectsthe calling' device impulse springs over condu'ctorsfjl"91` and 192, through alternate contacts 189 ing to the main automatic exchange'. After` 95. 190, directly to the trunkconductors lead-fV th 'called-rorparty at 'the 'mais automatic exchange has been selected and'ain'svvers, the operation of'thevtrunk circuit PClisth'e: same as previously described, and a further Vleu description of its' operation lis notl 'deemed` i necessary.

Thetrunk PC', of coursegris 'arranged so that. the' Subscriber F @am dal his Own an: nection. Connections can also'be extended to the branch exchange While the plug` isv in* Aa.jacln'ivithout ringingthe" connected subi scriber. In general, the circuit is'fcapable of use in establishing the sjameconnectinsf as more fullyQeXplainged in''connection'k with" c trunk circuit PC of Fig. Vl;

Referring; t. Fig. represents au.

r toinatic -Subj-station, Y an' individualf` Hilfe switch, 308 an autoinatic'selector switch, 3021'V kan automaticconnector switch, BOSthe 'bariliH terminals' of( the connector switch, and B06 an automatic lineA switch" or .anv aut-0inatiefA selector switch associatedfvvith the private'L branch ,exchange trunk and thefconduclzo tor's82l andAQ leading- `frointlie cenne"etfn` switch Ycontacts 304 arejonn'ected tythe" trunk circuity PG as isfwell underfstood;`V Of' 'l Course, any` number of selectors Ih'ayjbe in# serted inv the 'systemI according tos tliesizey of the automatic exchange; c

In working out our invention vvehaveexil?y plol'ed pfferred'circuit arrangements all of which 'tend to make eficient 1opcrafting" system, butit is te be understood that va# nece-ece 9 rious changes and modifications may readily be made without departing from the spirit and scope ot' our invention. Thereiormwe do not desire to be limited to the exact arrangement shown and described, but aim to cover all such changes and modifications as come within the spirit and scope of the appended claims.

'What welclaim as new and desire to secure by United States Letters Patent, is: l. A tele-phone system including a calling subscriber-s line, a called subscribers line, automatic switches and a trunk circuit provided vwith a manual terminal for interconnecting said subscribers lines, automatic means in the trunk circuit tor clearing the same when the called subscriber replaces his receiver se that, a second call may be eX- tended from said automatic switches to said trunk circuit'without operating the call bell at the called substation, and means for said trunk circuit for denoting a recall by the called subscriber.

2. A telephone system includingy a calling; subscribers line, a called subscribers line, automatic switches and a trunk circuit provided with a manual terminal for interconnecting said subscribers lines, and automatic disconnect means for said trunk circuit op erableby the called subscriber so that the trunk circuit is cleared betere the trunk cir-1 cuit terminalis disconnected from the called subscribers line, thereby permitting the called subscriber to operatehis automatic dial to edect a second connection or permit another subscriber to operate the automatic switches and extend a call to said trunk circuit without signaling the called subscriber.

3. A telephone system includingq a calling subscribers line, a called subscribers line, automatic switches, and a trunk circuit provided with a manual terminal for interconnectinn` said subscribers line, and subscribercontrolled means in said trunk. circuit for clearing the same so that the called subscriber may actuate his calling device to effeet a second connection or the operator may actuate her calling device to `effect a second connection prior to the time that the trunk circuit terminal is disconnected from the `called subscribers line.

4. A. telephone system including a trunk circuit provided with a manual terminal for connection to a called subscribers line, automatic switches accessible to said trunk circuit. an automatic calling device, and4 operators means for operating said calling device to control said automatic switches while said trunk circuit is connected to said subscribers line, said means being operable whether the called subscriber has his receiver on or eti the switchook.

5. A telephone system including a trunk circuit `provided with a manual terminal tor connectiomto a subscribers line, automatic switches accessible to said trunk circuit, a

calling` device associated Awith said trunk circuit, means for connecting said calling device to said trunk circuit to actuate said automatic switches to eilect a connection, and means tor said trunk circuit operable to bridge a condenser across the trunk circuit ybetween the sets4 of impulses of the called number. f

(i. A telephone system including a-calling subscribers line, a called subscribers line, automatic switches and a trunk circuit4 pro vided with a manual terminal 'tor interconnecting said subscribers lines, a dial for each subscribcrs substation, means in said trunk circuit for clearing thesame when a called subscriber replaces his receiver so that he may again remove his receiver and operate the dial at the substation to operate the automaticswitches to eii'ect a second connection before the plug in the trunk circuit is disconnected trom the called subscribers line,

and automatic means for said trunk circuit for denoting a recall by the called subscriber.

7. Aitelcphonc system including a calling` subscribers line, aY called subscribers line, a trunk circuit provided with Va manual terminal for connection to said called subscribers line automatic switches adaptedto be connected to said trunk circuit, means for informing the operator` at the trunk circuit that an automatic switch 4has been connected `to the saidtrunk circuit, a signal Jfor said trunk circuit operable when said trunk' circuit is connected to a called subscribers line, a disconnect signal7 automatic means for severingl the cuit, and subscriber controlled means for operating said automatic means and said disconnect signal..

strands ot the trunk cirl 8. A telephone system includinefa called l subscribers line, a calling subscribers line terminating at an automatic "exchange, a trunk circuit having1 a manual terminal for connection to a subscribers line, automatic switches at said automatic exchange for conneet-ing said calling subscriber to said called subscriber via said trunk circuit. a discon nect relay, and means operable by one ot said subscribers when he signals for discon nection for operating` said disconnect relay for discrnuu-fctinghis line Jfrom the othei` ot said subscribers lines and for again eiieet inn' an operation ot said relay to connect the said subscribers line to the trunk circuit when theV subscriber signals for a recall.

9. A telephone system including a calling: subscribers line and a called subscribers line, a private branch exchange having a trunk circuit provided with a` manual terminal for connection with said called subscribers line, automatic switches adapted to connect said subscribers lines via said trunk lli) circuit, "a relay forsaid trunk circuit, a second Vrelay for said trunk circuit, means controlled by said vcalled subscriber for disconnecting his line `from the trunk conductor leading' to said kautomatic switches aindfor ybridging the battery at the -privatebranc'h exchange across his line, :whereby When he reinoves hisreceiver to institute a recall he energizesvthe said second` relay to cause the operation of said-first relay to again connect his line'to 'the automatic exchange over the said trunkcondnctors.

w10( VA telephone system including a main excliange,"a.private branch exchange, auto-A matic switches at said mainexchange and a trunk circuit having a manual terminal `at said private branchexchange for connectiing'a subscriber at the said automatic exchange, a relay `for said trunk circuitk controlled by the subscriber at the private branch exchange and operable to connect 4either the battery at the private branch exchange' or the battery at the main exchange' across the said subscribersline.

l-l. A telephone"system'including'4 a calling subscrlbers vline terminating at a main Nexchan e automatic switches at said -1nain exchange, a called subscribe1"s lineterminat- Ving at a private branch exchange, a Vtrunk circuit at said private branch exchangey provided Witha'inanua'l terminal for connection Vto'said called subscribers line, said auto matic switches and said trunkiv circuit for vinterconnecting the said subscribers lines, a Y relay controlllnglthe connection of n said call `lngsubs'cribersV line to said called subscribers line, and `a Second relay controlled vover said called `subscribers hne,1said second relay. being adapted When said called subscriber replaces his receiver, to operate Vsaid first krelay to l disconnect said subscribers lines, saidl relay upon` the snbsequent're- Inoval of said subscribers receiver operable to again connect the subscribers lines.

12. A telephone system including a calling snbscribers lineuterminating at a main exchange,;avcalled subscribers line terminating at a branch exchange, automatic switches at said main exchange and a trunk circuit at said branch `exchange provided with a inanual terminalu 'or-interconnectingy the said subscribers lines, dialing means ior the `operator at said `trunk circuit, subscribers dialing means, .ln'eans1 controlled by said calledjs'ubscriber for disconnecting his line from the trunk conductors leadingto' the said vautomatic 'switches,upon the replacing of his` receiver upon itsswitchhook, means operable to again connect his' line' to the said automatic exchange, means whereby the said' calledsubscribermay then dial to operatethe'said switchesat said main exchange and means whereby the `operator at the said trunk circuitina'y'be informed of the recalll and operate her dialing` means toj/operate ythe said' automaticlswitc'hes at saidrmain exchange. l f

Signeclbyu's at Chicago,in theyc'ountyof Cook and State ofl'llinois, this4th day of March, 1925.",` y i l Y HIRAM D. CUR-BIER.

WILLIAMAG. SHELL.'

Images