US1504337A - Telephone system - Google Patents

Description

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H. M. FRIENDLY TELEPHONE SYSTEM Filed May 1e. 1921 9 sheets-sheet '7 vH. iw. FRINDLY TELEPHONE SYSTEM vFiled May 16. 1921 9 Sheets-Shet a ,E i w -2-5L mm; n E r m m m r n m m n m Tm H www. H T IL il! @nu Q RQ s@ f4 www QQTQ W\%/ Patented ug. l2, i924.,

HERBERT IVI. FRIENDLY,

on PORTLAND, OREGON.

TELEPHONE svsrnia.

Application filed May 16,

To aZZ whom t may concern Be it known that l, HERBERT M. FRIENDLY, a citizen of the United States, residing at Portland, in the county of Multnomah and Sta-te of Oregon, have invented a certain new and useful Improvement in Telephone Systems, of which the followingis a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

The presentinvention has for its ybroad objects, the improvement of telephone systems in general and more particularly automatic and semi-automatic systems, looking toward the affording of operative conveniences to users and switching attendants which have been heretofore unknown.

The invention in the specic form chosen for the illustration herein, contemplates a so-called two-wire common battery automatic telephone system as has been widely used, the present invention necessitating novel departures from equipments heretofore known, in attaining certain new objects, while retaining certain operative functions which are known.

The exampled form of the present invention chosen to illustrate it contemplates its adaptation to a comprehensive automatic telephone exchange` system, and hasr for a salient object the enabling of an attendant, or other party who has received a call from a subscriber, to transfer or pass the connection to further connection or connections. For example, a subscriber calls the information operator by the usual automatic means, and, upon the response of the attendant, informs the latter with whom he wishes to communicate. The attendant, after ascertaining the telephone number of the wanted subscriber so informs the calling subscriber. '.lhen, the calling subscriber may release the connection andre-initiate the call, directing it to the proper telephone number through the agency of the usual automatic means, or, as contemplated in the present invention, the attendant can, through the agency of a dial calling device or a pre-setting calling device, transfer or pass the connection directly from the calling subscribers to the wanted subscribers telephone and release the equipment leading to the attendants switchboard, thus leaving it free, and there- 1921. Serial No. 469,886.

fore, again seizable to other calling subscribers.

rlhe present invention, in its illustrated form contemplates not only means for forwarding the call to the wanted line, butl also contemplates controlling and supervising the connection in various ways as will appear. The present invention, as will appear, contemplates as one of its objectsrthe establishment of a direct path 'between the calling and the wanted telephones when switched by the attendant, regardless of the location'k of theattendant as relates the location of the calling and the wanted telephones in the exchange.

Another object of the present invention is to afford means so the said attendant can continue the connection through a terminating switching cord and plug, or through a set of independent companion cords and plugs. These auaptions would be employed. where it is desired to continue the connection to a manual switching means, or through a combination of automatic control and manual switching. The invention is also applicable to automatic private branch exchanges.

The present invention, therefore, has wide adaptations, and moreover, would in many instances involve a different application for the same nominal use in the same exchange, depending, for example, upon the location of the attendants switchboard with relation to the calling telephone in a multi-office eX- change system. That is to say, whether the attendants switchboard is in the same mainbranch office district with the calling party, or not.

In accordance with this invention applied to the system chosen for its elucidation, each telephone line terminates in a line switch, and the latter have commonacccss to a plurality ofr first select0rs. The rst selectors Y have common access to a plurality of second selectors, which latter have common access to a plurality of third selectors. The third selectors have common access to a pluralnjv of connectors, which latter have commonV access to certain groups of subscribers lines. In addition to the foregoing, the first selectors have common access to a group of selectors-which may. be termed special sec` ond selectors. The latter have common access to special trunks, telephones and equipments off certain levels and have common access to the said second selectors off corresponding levels with the said first selectors.Y In practice, the first level of the first selectors would ordinarily extend to the special second selectors., c

Assume, now, that 'a 1 is sent by the calling subscriber` accidentally or directedly before digit 2, for example, is called, in Vcalling a telephone number beginning with digit 2 A trunk Adta Vgroup foff'ftrunks leadingfrom the first level of the first selector to a special second selector-willbe attained. VThe-n, 1upon the digit 2 being` called, `the special second :selector seized will attain connection' through its fsecondrlevelf with tlregrou-p oit'trunks extending-Lto secondselectors from the second lev'elof the first selectors in com-mon w-h "che secondlevel of the l'special second selectors. In View 'ofv the -foregoing, regardle'Ssbf the 4initial'*digit being 1 or 2, the fs'arne-1grorip Vof vtrunks exten-ding tol seciond'fselectors'is attained. That is tosay, if ateleph'one number beginning with digi-t 2 is called, prefixing digit 1 will not vitiiatethe call.A However, if the first digit ""1-is-f`=ollo'wed by digit 1, the-special second "selector will selecta trunk on its j firs't" level. These Ilatter trunks may 'extend tto-:special oliice attendants, as, information, Jwirechief vland-c'cnnplai-nt switchboard, -or to vtelephcnes. `-Special :second *'selectors, and

"also A"the -first `selectors, functioning as *de- "scribed have-been 'use'd heretofordand are ywellknown. n

- VElioWever, "the present invention among other novel features contemplates :.a -companio'n selector asC ifn correlation (or 'adapt- 'edto Ybe rassociated through the agency of a selectin-gl switch) with each special second selector asBy-and that-the yattendant receiv "ingftheV call* can, by automaticcontrol means lc'aiisejthe' said 'companion selector to' operate and attain connection 'with a succeeding vC"s`fecofnd-"-r special second) second selector or a 'succeeding [special second selector 'of the `grcruo `containing selector YB "which may be thereafter operated under control ofthe attendant to the end of-completing a connection through the exchange apparatus to the wanted telephone essentially as if the calling 'subscriber himself had controlled the con- `n'ecti'on automatically -ffronifthe first 'selector directly, inli'eu lof first calling the attendant. The attendantmay'conversewith the wanted subscriber privately or witlr-thecalling sul scriber also in telephonie relation. Means is-'provided for Vreleasing the special second selector B coo'perating with the first select'or A and the apparatus towards the attend- `ants'switchboard,so .the links will then be direct from Athe firstfselector'A to the companion?- secfnfd` selec'torf-Cas"sociated with the C as in a normal connection from a first selector, directed wholly by the calling subscriber.

Where the attendants switchboard is in a mainfbranch oiiice district of the exchange, remotely located from the main branch oiiice district containing the calling subscriber, the call may route over trunks reserved cX- clusively for such service oli' the first level (or other level or levels) of the special second selectors, or they may route over the regular eXchangertra-Fic trunks provided for general switching between subscribers. A forni of trunk repeater of my invention is provided enabling the dual use to be enjoyed as will be detailed presently. In instances, a cer tain number of special trunks, also involving a trunk repeater of my invention, would be provided extending from the various main-branchvoiiices to the attendants switch board, and other last-choice trunks, perhaps, used for general switching, reserved for the dual use, would Vbe available when all the special 'attendants trunks are busy.

In the accompanying drawings Fig. 1 shows a subscribers automaticltelephone T 'leading to a pre-selector PS, and the latter is in selective relation to a first selector A. A is in selective relation to second selectors and special second selectors. These elements, in the indicated relation are well known in the-art.

Fig. 2 shows a novel special sccoiid lector, B.

Fig. 3 shows Aa novel 'companion selector to B Fig. A is a diagrammatic representatnm oi a second selector 2S, third selector con- -nector CON, and a called line leading to telephone T4. These elements, in thc indicated relation, are well "known in the art.

Fig. 5 shows a novel trunk repeater. Fig. 6 shows a novel dual-service trunk repeater.

Fig. 7 comprises a second selector F. a third selector BS', a connector CONT. and a called telephone YT l'. These elements. in the indicated relation, are well known in the art.

Fig. 8 shows an attendants receiving circuit. l

Figs. 9, lO, l1 vand 12, rcspectivelv.` show a method of arranging the 'various figures to `form ope ative circuit' relations (as will be described.) suitable-to elucidate they invention.

Fig. 13 shows a switchingl cord pair for continuing a connection from the springj ack in Fig. 8 to a called manual coinn'ion battery une H. t

Fig. 14 shows a plug-ending connecting llO circuit attaching to the right of Fig. 8, and a called manual common battery line li.

Referring to certain of the various iigureszf ln Fig. 1, T is the usual series type of automatic telephone having a. calling device 12 of the general class as shown in British patent to Dicker, No. 29,654 ot 1910. The pre-selector PS is ofthe general class as shown in U. S. patent to Lamb, hl 1,193,- 160, granted August 1, 1916. The lirst selector A. is of the general class as shown in U. S. patent to Keith and Erickson, No. 815,321, granted March 13, 1906, of course modified in mechanical and circuit details to operate on the Well known so-called twovvire principle.

ln Fig. 2, special second selector B, is ot the same class as A of Fig. 1, of course having novel operative functions, as Will appear.

In Fig. 3, selector C, which is companion to selector B, is of the same class as A of Fig. 1, ot course, having novel operative function, as will appear.

ln Fig. 4, second selector 2S, is similar in detail to selector A. Also, third selector 3S, is similar in detail to selector A. Connector CCN, may be assumed similar in de tail to the connector H shown in U. S. Patent No. 13,901, reissued April 13, 1915, to Frank Nevvtorth. Pre-selectorl PS4 is similar in detail to pre-selector PS. Telephone T4 is similar in detail to telephone T.

1n Fig. 7, second selector F, is similar in detail to selector A. Third selector 3S is similar in detail to A. Connector CCN? is similar in detail to selector connector CON. Telephone T7 is similar in detail to telephone T.

To simplify the dra-Wings and descriptions, battery and ground are shown as independent sources throughout, Wherever applied.y but it is to be understood that the system'is ot the common battery type. In the descriptions, When a circuit is traced to a winding, the opposite terminal ot which is shown applied to grounded battery or to ground, the described circuit is to be con` sidered as traced to ground through the winding to battery, or direct to ground as indicated.

The performance ot the equipments will be detaiied under ditte-rent assumed operative conditions, bearing in mind that the equipment elements may be variously organized in the assembly ot a system.

Referring to the accompanying drawings: i

Assume a call troni telephone T to telephone T4, the telephone number of Which is 31111. The Figs. 1, 2, 3 and 4 are assembled in numerical order as shown in 9, however, Figs. 5 and 8 not entering into the present assumed call.

VUpon the calling subscriber initiating the call by removing the receiver from the switchhook oi telephone T the pre-selector PS will function in the Well known manner and extend the connection to the first selector A, which latter is assumed to be the iirst seizable first selector of a. group accessible to the pre-selector PS. it circuit exists after the seizure oi selector A, from grounded battery, upper Winding ot control relay 13, armature 14, conductor 15, pre selector .viger 16, conductor 17, telephone T, conductor 18, pre-selector Wiper 19, conductor 20, armature 21, loaver Winding ot relay to ground, relay `13 actuating. Slow-releasing relay 22 is energized through grounded armature Private conductor 24 is grounded through Contact Cut-oit' relay ,CR is maintained from conductor 24 in the well known manner.

Upon the calling subscriber operating the calling device in accordance With the lirst digit 3 the shaft of selector A t driven by vertical magnet V) will be caused to' be raised three vertical step-s, its Wipers aligning with the third bank level, and then caused to be automatically rotatedin (driven by rotary magnet R). The ivipers 26, 2 and 2S will be rot-ated until they engage and seize the first idle trunk in the well known manner. it will be assumed that the set ot' bank contacts seized is 29, 30 and 31, being the tiret set ot the level. Relay 32 Will actuate in effecting the seizure.` Relays 18 and 22 will cle-actuate in sequence. fr telephonie circuit can now be traced from armature 1.4, conductor 32, Wiper 7, bank contact 30, conductor 83 to grounded battery through the upper Winding oit a control relay ot the second selector 2S corresponding to relay 13, and from ground through the lower Winding of the said control relay in selector 2S, conductor .401, bank contact 31, Wiper 28, conductor 34 to armature 21.V Conductor 402 will become groundedltrom the slow-releasing relay in selector 2S corresponding to 22 Which will maintain ground on conductor 24, and therefore relay 32 Will be maintained actuated and busy ground will endure on bank contact 29 and its multiples.

Upon operating the calling device 12 in accordance with the second digit l, second selector 2S will be caused to raise its Wipers one step to align With the tirst level ot bank contacts, and automatically rotatein thereat and seize the first disengaged trunk, Which Will be assumed is the one leading to third selector 3S.

Upon operating the calling device 12 in accordance with the third digit 1, said third selector 3S will be caused to raise its Wipers one step into alignment with the Erst level of bank contacts and automatically rotate-in thereat andvseize the rst disengaged trunk which `Wi-ll be assu-med to lbe fthe -one v*leading to connector CON.

Uponl"operating the calling device l12 in 'accorda-nce with the fourth digit I, the lsaid conductor will be caused to raise `its Afwlipers-to align with the first :level of bank contacts. Y

lUpon `operating the calling device 12 in 'accordance with vthe "fifth (last) digit"1, ithe `w'ipel-s ofthe said connector will be lcaused to -be rotated-one step and engage, lseize and signal u'ponthe line extending `to "telep'lfione T131; allin a manner well known. Vvitlre `release 'of the described established --eonnection -upon the .calling subscriber re- =-stering lris receiver will not be detailed, since the functioning of the concerned ele --inents, which are lold in 'the art, is well known Assume a call l'fromtelephone T to tel-ephone'T, thek telephone number of which is "`21111. The figures -willbe assembled'as sho-wn infFig. 11,though Fig. S indicated therein has no operative relation in the pres- ;entassumed call. The call will lbe initiated in the l'manner-before described, andthe callingsubscriberwill first operate thee-alling device 12 inaccordance with'digit 2 'inlieu'of digit 3, whereupon the selector will `seize :the first `trunk in the second level 'in the manner set forth, wipers 26, 27 and1` 28 sei'zing'bank contacts 35, 36 Vand l37 respectively. A circuit can now be traced "fromthe v`calling' telephone .T `to the said -c`ontaictsj`36and 37 Aandrfrom said 36, Yconductor 38, conductor 39, armature 160,1, `contact i602, upper Awinding of relay 603 to `grounded battery, and lfromV ground, lower winding of relay 603, spring 604, armature 605, Yconductor 606, conductor 201 to contact 37. y The windings of relay "603' will thus `operatively energize in'series with the cal-ling "telephone V"F. Slow-releasing relay 607 will;actu'ate due' toV ground on armaturel 608. vGrroun'd l'from contact 609 is applied over conductor 610 to 'conductor 202 and to its *inultipled private bank contacts35," 203 and *301. `This will `maintaiirground on conductor 24,"andrelay 32 will be maintained actuated as before'set forth. Ground from contact 611 is applied' over conductor 612 Vto private'banlr contact 204 and multiples accessible to special ksecond selectors similar to "Tlu1s,when repeater vE is` seized by afirst selector, or'by a'special second selectoras B, as will appear, `the trunk' is incidentally guarded against the other.'first'jseleotors andspecialc second selectors, not shown. A circuit can now be traced-'from groundedv bat- ;tery through upper winding of Acontrol relay' 701, armature 702, conductor 703, cond-u'c't'or'613, Contact Y614e, contact 615, inner wind-ing of relay616, contact 617, lower .Windingof-relay 61'8, contact l619,' conductor i615'4620-,i-.conductor 704,-"armature705, through ture.

lower winding'of relay 701 to ground, relay 701 actuating.

fUpon'th'e callin-g subscriber operating the calling device 12 in accordance with the second digit"1, the control relay 603 will -de-actnate and re-actuate one 'time responsive thereto, ope-ning the described circuit including the windings of'relay` 701 `at contact 619. Slow-releasingfrelay 622 will actuate incidental to relay 603 (le-actuating, due-totheclosurefof a circuit from the winding of said A622, arinaturef623 to grounded ai-imature608. At 'the termination of the period-of relay 622 following the ref-actuation of-relay 603, after calling device 12 has returned to normal relay 622 will deactuate, restoring the traced circuit includ- -i-ng the windings of re'lay70l. @peiling the energizing circuit of relay 701 for an instant ra-s-describedywill cau-se the'vertical magnet V7 to raise the shaft carrying the wipers 706, 707 and 708 to an alignment with the ffirst level,whereupon the rotary n'iagnet R7 will automatically ivfunction to rotate the wipers into engagement and seizure of the iirstbank contacts 700,710 and 711` respectively, which is assumed to'be the .first set idle contacts leading to an accessible third selector3S. The vfunctioning' of selector -F is'wfe'll known in the art and will therefore not be detailed.

Upon the calling subscriber operating the call-ing device'12 in accordance with the tlii-i-dgrlfiigit1,relay 603 and other elements ofirepeater 'E willfunction as before Vde- -Scrb'ed,-bearing in mind that this time the relay 701-is disassociated due to relay 712 having -actuatedlto effect the Vstated seizure of'selector 3S', andA that conductors 703 and 704 have therefore been continued through wipers 707and 708 and bank contacts 71.0 and 711 respectively, to a control rel-.1y in third selector 3S similarto and disposed 'as oontrolrlay '701. Thus, the third selector3S will be caused to function like =selector'-F vfunctioned as set forth, and the connectonCON7 is seized through wipers 713 'and'714, ydisassociating the said control relay in said selector 3S corresponding to 701. Then, connector CON7 will operate -responsiveto the two last digits"1-1 in a manner as described in relation to connector-CGN, and seize and ring upon the lineI leading-to telephone'T7, the repeater E functioning as before set forth.

lThe connectorCON7 (bearing in mind the cited referencel thereto) reverses the battery projected over the leading-in conductors including the inner Winding of relay 616. lheirrelay607 actuates, a circuit from the outer windingof relay 616 to grounded contact/609 is closed. The said out-er winding, kthough energized, is alone insufficient to caus'e'the attraction of its iniuenced arman The "direction of current traced through the inner winding (before aresponse from the telephone T7 1s such as to tend to neutralize the energization of the outer winding of relay 616. Therefore, when the current projected from the control relay (relay 16 in the said cited patent to Newforth) is reversed consequentto the response of the called telephone, the currents in the inner and outer windings of relay 616 will energize cumulatively, effective to attract its influenced armatures. A circuit can new be traced from the winding of relay to grounded contact 625, relay 624 actuating and reversing the leading-in, line relation with respect to the windings of rela-y G03. Repeats-rs functioning as specifically set forth with respect to repeater E are well known in the art. However, as will appear presently, there are other functional characteristics and circuit .details of said repeater E which are novel and relate to the present invention.

lUpon the calling subscriber at telephone T replacing the receiver, relay 6,03 will deenergize, opening the circuit including line conductors 613 and 620, and therefore, the connectorI CONT, selector 3S", and selector F will restore in the well known manner. The foregoing traced calls from subscribers telephone T to subscribers telephones T4 and T7 is by way of showing the normal traffic uses of the system involving the present invention.

Assumel that in calling telephone T4 from T, a preliminary impulse constituting digit- 1 will be introduced, Theinupon initiating the call by removing the receiver from the switchhook of T, rst selector A will be seized as before set forth. The introduction of an open impulse constituting digit 1, after the said seizure, by an accidental operation of the switchhook or by a directed manipulation of the calling device 12, will cause the selector A to function as before described, only in this instance it will rotate-in automatically on the first bank level and seize the first set of bank contacts, they being assumed as idle when engaged. lllipers 26, 2? and 2S are thus in engagement with bank contacts 36, 37 and 238, loading to conductors 39', 40 and 41, and conductors 42, 43 and 44 respectively. The latter conduct-ors lead into the novel special second selector B. Attention is here called to the fact that the said selector B, as regards the portion including control relay 210 and the equipments on the right thereof constitutes the same arrangement and circuit detail with relation to conductors 44,

and 42 as selector A does as regards conductors 20, 15 and 24 respectively. Relays 206, 207 and 208 vand associated circuits have functions as will appear, but for the present may be assumed lined in the circuit disposition shown. Under the, latter assumption,`

the special second `selectonBl is in detail equivalently similar to selector A. Tt may be remarked here that specialsecond s'elecA tors of the kind shown in A of Fig. 1 (and the equivalent assumed condition of selector B) are old in the art, though its operation will be somewhat detailed to insure the fullest comprehension of the adaptations of the pesent invention in the system illustrative o it.

At this juncture a circuit may be traced from grounded battery through upper winding or relay 210, upper armature of relay 205, armature 211, contact 212, conductor 44, conductor 41, bank contact 37, wiper 2?, conductor 82, armature 14 and over the described path through telephone T to armature 21, conductor 34, wiper 28, bank contact 38', conductor 40, conductor 43, contact 213, armature 214, lower armature of relay 205, lower winding of relay 210 to ground, said 210 actuating. Slow-releasing relay 215 will actuate due to its winding being grounded through grounded armature 216. A circuit can now be traced from grounded contact 217, conductor 42, conductor 39', bank contact 36, wiper 2G to conductor 24, which latter will operate to maintain the pre-selecA tor PS and the first selector A in a manner as before set forth. i

Bearing in mind that the respective bank contact-s of the third level accessible to said selector A and said selector B are Ain multiple relation, common to the leading-in conductors of second selector 2S, it is manifest that if the first digit 3 of the telephone number 81111 belonging to telephone T4 is now called from calling device 12, special second selector will be caused to function as set forth in describing the operation of first selector A when digit 3 was called, wherein no preliminary impulse was transmitted. That is to say, the shaft of said selector B will be raised by the ver-tical magnet V2 so the wipers 218, 219, 220, 221 and 222 align with the third bank level, where the wipers are caused to be automat-ically rotated-in, driven by the rotary magnet R2, until the first idle trunk is encountered and seized. This seized trunk will be assumed to be 'the first one of the bank level, being the one leading from the set of contacts 223, 224, 225, 226 and 227 respectively. The said seizure, of course, implies that relay 205 will actuate to cause the seizure, and that relays 21() and 215 will restore in sequence. l/ Vipers 219 and 220 have no operative purpose in the present connectiolvi. It is apparent in the drawings the bank contacts 223, 226 and 227 aref-as sta-ted) in multiple relation with bank contacts 29, 3Q and 31, and with conductors 402, 33, and 401 respectively, which latter lead to the leading-in termina-ls of second selector 2S. So through the agency of selector B an alter- `calling telephone numberV 21111,

native path from selector to selector is 'formulated consequent upon prefixing digit 1 to the first digit 3 of the number of the called telephone. It will'be manifest from the disposition of the bank contacts of selectors A and B set forth at the outset Vthat this expedient-is correspondingly operative regardless of what (certain) first digit of a telephone number is called. For example, if digit 1 were prefixed when ,being telephone T7, the special second selector i3 would attain the sa-me'outgoing trunk leading through repeater E to second selector F,

offY the second bank rlevel of said selector B, as if the digit 1 were not set and that. selector A responded primarily to digit 2.

In commercial telephone exchangeV systems the employment of the first level of the first Vselectors as uit. relates to Vgeneral subscribers numbers'is not found satisfactory, due to the fact that preliminary or false impulses constituting Vdigit 1 are often introduced, either by carelessly removing the receiver from the switch-hook and thereby effecting an open impulse, or through introducing the y said impulse otherwise. The nominal capacity of the exchange systern. is thus reduced one Operative level,

so far as general subscribers are concerned. It is found convenientin instances to employ the said first level in gaining connection with company or exchange attendants equipinents,and, ashas been set forth, to divert a call which has become vitiated through av preliminary impulse, back into its normal selective route towards the wanted telephone line.

lt will lbe assumed for the present that the inform ation department in the eXampled system is reached by calling telephone number '14. Attention is directed to Fig. 9, which shows the rel-ation ofthe various figures in the circuit assembly about to'be described.

To avoid involvingv the drawings too neatly, the lower level of bank contacts l-l ovn accessible to selector B (and other similar selectors of the group) is, in the escription about to be entered into relating to the call to the information department is assumed to be lthe fourth level, rather than the first level as it is shown in the drawing.V -Fig'. 8 is for the present assumed asA constituting theessential equipment elcments at t-he switchboard of the said information department,r

Y.The calling subscriber at telephone T will initiate Athe vcalland attain the first se- VVlector'it by removing the receiver, and

thereafter attain the special second selector B by 'operating v`the calling device 12 in acfcordancewith digitV 1, as before detailed, Upon operating the calling device j 12 in accordance with the second digit 4,7

the selector B will function in the manner, generally, as before described in relation to digit 3 thus attaining the fourth bank level and there automatically rotating the wipers 218, 219, 220, 221 and 222, selecting the first idle trunk, which will be assumed as being the one leading from the. first set of bank contacts 204, 232, 233, and 235, of course, bearing in mind that for the present convenience of illustration the said fourth level is shown as the first level bank contact set.

A circuit can now be traced from grounded battery through upper winding of relay 501, conductor 502, bank contact 234, wiper 221, conductor 236, armature 23T, contact 212, over the described path including telephone T to contact 213, contact 238, conductor 240, wiper 222, bank contact 235, conductor 503. lower winding of relay 501 to ground, relay 501 actuating. Fig. 5 being preferably in the same exchange main-branch ottico district as selectors B and A and telephone 'l` affords transmitter excitation battery lo telephone T of ample strength.

An operative circuit can. now be traced from thc winding of slow-releasing relay 504 to grounded armature 505. Ground on contact 506 will be applied over conductor 50T to bank contact 204 and its multiples, guarding the repeater D against seizure by ,other selectors similar to selector B in common access to it, and it also serves to maintain selectors B and A and preselector PS in a manner as has been setfortli. A circuit can also be. traced from grounded armature 509, winding of relay 510, conductor 511, conductor 801, retardation coil 802, winding of relay 803 to grounded battery. Relay 510 is marginally adjusted not to operate with thev resistance value of said 802 in circuit as traced, but will operate if said 802 is shortcircuited. Relay 803 will operate under either said condition relating to retardation coil 802. Relay 803 being thus caused to be actuated, calling lamp 804 will have battery derived through it, armature 805 to grounded armature 806.

The attendant at Gr upon observing the glowing of lamp 804 will respond by manipulating key 807.

The telephonie circuit from telephone T to bank contacts 234 and 235 has been traced and the said circuit is now continued over conductor 502, condenser 512, conductor 511, conductor 801, spring 808, spring 809, conductor 810, through operators set T8, conductor 811, spring 812, spring 813, conductor 814, conductor 513, condenser 514, conductor 503 to bank contact 235. The, subscriber at telephone T is thus in telephonie relation with the attendant at G.

Incidental to the manipulation of key 807 an ope-rat-ive circuit is closed from the winding of relay 815, make-before-breuk spring Leones? 816, to grounded spring 817 Armature 806,

y attracting, opens the traced energizing circuit for lamp 804 and closes a circuit to ground from lamp 818. rlhus, upon the manipulation of key 807 lamp 804 is extinguished and lamp 818 is caused to glow. A locking circuit for relay 815 is closed from its winding', spring 816, armature 819, to grounded contact 820. Relay 803 is held actuated dependent upon armature 509 of relay 501, and the latter relay is, in turn, held actuated dependent upon the maintained closure of the circuit including telephone'l, also upon the dis-association of the wipers 221 and 222 from. bank contacts 234 and respectively. So the lamp 818 will glow until the selector B releases from its seized bank contacts, or the calling subscriber replaces the receiver.

llt may be stated here that under t-he condition wherein lamp 818 is glowing and .lamp 804 is extinguished the calling subscriber can cause the said 818 to extinguish and lamp 804 to lie-glow to attract the attendant. This is done by manipulating the calling device 12 (or by flashing the switchhook) so as to open the energizing circuit of relay 501 for a brief period and thereby cause its armature 509 to retract, and in turn open the energizing circuit of relay 803. Relay 803 will de-actuate momentarily and re-attract upon the re-attraction of armature 509 when the circuit including the windings of relay 501 is nei-established. Since relay 815 is maintained locked through contact 820, it (815) will become unlocked and lamp 818 will extinguish, and lamp 804 will re-glow. Were the armature 509 and its co-ope-rating contact transferred to'` relay 504, the circuit operation described would not be altered, only, now, that asl relay 504 will sustain over current lapses of the period effectuated by thecalling device 12 wherein armature 505 retract-s responsive thereto, no re-glowing of lamp 804 as set forth can ensue unless the call is eifaced and rte-established.

lt'will now be assumed that the calling subscriber' is enquiring for the telephone number of telephone T4. The information attendant (at (i) informs the subscriber the number is 31111, but in order to save time and effort to the calling siiibscriber, that the. connection will be given him and for him to hold the receiver, whereupon the attendant at G Will manipulate the key cam 821 toirestore key 807 and operate key 822.

Springs 823 and 824 short-circuit the retardation coil 802, which function will augment the current` flow in the traced path, including relay 510, to its operating value, whereupon ground from contact 4515 will be applied over conductory 516 to bank contact 233, wiper 220, armature 241, conductor 242, to the winding of relay 302, causing said 302 to aetuate. An operative circuit can new be traced from grounded contact 303, conductor 305 to the winding of slow-releasing relay 208e Also, an operative circuit can now` be traced from grounded armature306, conductor 307 to the winding of relay 206. Bearing in mind that conductor 42 now receives ground from contact 506, a locking circuit exists from the wind-- ing of relay 206 through its lower armature to said conductor 42, maintaining relay 206.

lt will be observed that at this juncture retardation coil 250 (through inside makebefore-break springs of relay 208) is in bridge of armatures 211 and 214, and therefore, included in series with the windings of relay 501, maintaining said 501. An operative circuit can also be traced from grounded battery through the upper winding of control relay 308, armature 311, armature 214, winding of retardation coil 250, armature 211, contact 245, conductor 246, armature 315 to ground through the lower winding of relay 308. Also, an operative circuit can be traced from grounded battery through the lower winding of relay 316, conductor 317, armature 247, conductor 44, through the traced path including telephone T to conductor 43, armature 248, conductor 249, to groundthrough the upper winding of relay 316. rllhe object of relay 316 will appear presently. v

A circuit path can now be traced from the winding of relay 207, conductor 255, armature 320, conductor 321, armature 257, wiper 219, bank contact 232, conductor 258, conductor 520, conductor 513, conductor 814, springs 830 and 831, conductor 832 to free dial spring 833. A conductor 835 is legged ofl1 conductor 832. It branches to key spring 836 and to armature 837. The purpose of said 836 and 837 will appear presently.

The information attendant at G will now preceed to operate the calling device CD in accordance with the successive digits of the telephone number 31111 of the wanted telephone T4. Upon the operation of the calling device CD in accordance with the iirst digit 3," grounded spring 838 will be applied to spring 833 for three brief periods, thus closing the traced circuit path including the winding of relay 207 correspondingly.

It follows, that consequent to the actuation of relay 207the traced circuit path including the windings of relay 308, will be opened three times. VBearing in mind that relay 302 is actuated (and therefore armature 322 is in engagement with its co-operating contact) and that the armature 328 and its (3o-operating contact are auxiliary and have no direct operative purpose in selector C, it will be manifest that the circuits of said C are similar to those of rst selector A, and therefore, the operation of seleccontacts, through the agency of vertical magnet V3, and then caused to be automatically driven rotarily through the agency of the rotary magnet R3. The said rotary functioning will proceed until an idle trunk is encountered, when it will seize its ternir nating bank contacts, relay 330 actuating in the well known manner, whereupon relay 308 and slow-releasing relay 331 will deactuate in sequence; also in a manner well known. It will be assumed that the set of bank contacts seized is the first set of the level, 335, 336 and- 337 leading to conductors 402, 401 and 33 respectively. The said latter conductors have been described as leading to the leading-in conductors of second selector 2S.

Upon the said calling device CD being next operated in accordance with the second digit 1, said 2S will function in the manner as before set forth and select and seize the trunk leading to the third selector 3S. Upon the said CD being next operated in accordance with the third digit 1, said 3S will function in the manner as here-tofore set forth, and select and seize the trunk leading to the connector CON. Upon the said OD being next operated in accordance with the fourth digit 1, said CON will operate, and seize and ring upon the line leading to telephone T4 in the manner as hereinbefore set forth.

It will be assumed that at this junct-ure the Wanted party has not yet responded before the attendant at G restores the key cam 821 to normal, the forwarding of the call having been completed. Relay 510 will deactuate due to the short-circuit around the retardation 802 having been thus removed. It follows that relay 302 will cle-actuate and also its dependent relay 208, relay 206 remaining locked to conductor 42. After the period of slow-releasing relay 208, an operative circuit can be traced from grounded contact 340, lower armature of relay 208, conductor 260, armature 323,' conductor 343 to the winding of the release magnet Rc2, causing selector B to be restored, where- -upon relay 501 and its dependent relay 504 will de-actuate in sequence, and relay 803 i will ole-actua-te because of the retraction of armature 509. .The relay 815 will have its locking circuit opened at contact 820, so lamp 818 .will extinguish, indexing the condition.V Due to conductor 402 being now also grounded from the connector CON, conductor 42 will not be subjected to a ground lapse, because of armature 506 retracting, and therefore, relay 206 will remain actuated and relay- 210 disassociated. The telephonie circuit traced from telephone T to conductors 43 and 44 and the telephonie conductors traced from telephone T4 to conductors 312 and 246 are joined through contact 213 and armature 214; and contact 212, armature 211 and Contact 245; respectively, and, furthermore, it is clear of operative and affecting connections from the telephone T to the connector CON. Sc-

lector B having been released, the repeater D and its leading-in trunk is now available to subsequent calls.

Upon the calling subscriber replacing the receiver at telephone T the connector CON will be released and ground will be removed from conductor 42 in the well known inanner, and the said connector will restore and relays 330 and 32 will de-actuate because thereof. Release magnet R03 will restore selector C due to its energizing circuit be coming similarly closed.

It has been stated and set forth that while the described iinpulsing was ensuing, the calling subscriber is cut off from the wipers of selector B and terminated in the wind ings of relay 316. The purpose of this is as follows: Upon relay 208 actuating. no great disturbance due to a lapse of current is heard through the receiver at telephone T, because no lapse of excitation battery is entailed incident to deriving current through the windings of relay 316 in lieu of through the windings of relay 210. The relay 310 also serves to release the connection at any instant under control of the calling subscriber at telephone T, regardless of the fact the attendant at G may have taken control and may be forwarding the call as described. For example, should the calling subscriber at telephone T replace the receiver while relay 208 is actuated and key 822 is operated, as set forth, relay 316 will cle-energize and de-actuate4 An operative circuit will then ensue from release magnet R02. conductor 343, conductor 344, armature 345, conductor 346, armature 259, conductor 341, to grounded contact 340. The selector B will thus restore, whereupon the trunk leading to the repeater D will be disengaged and lamp 818 will extinguish, indexing the condition.

Assume that before key 822 is operated and while key 807 is operated as set forth hereinbefore, the calling subscriber at telephone T replaces the receiver. Under this condition relay 205 is the only relay operated in selector B, and all relays in selector C are normal. Relay 501 is energized over a circuit including telephone T under this condition. Therefore, when the receiver at telephone T is re-placed, relay 501 will deactuate and remove the holding ground from the Winding of relay 205, causing it to deactuate and complete an operative circuit from grounded armature 216 armature 260, armature 261, spring 262, to release inagnet R62, causing the restoration of selector B since relay 501 is cle-actuated, its dependent relay 803 will de-actuate, and lamp 804 Will extinguish. lt will appear presently that were alternative answering key 840 operated (cani 821 being normal) and the calling subscriber at telephone T replaces the receiver, the saine functioning of selector' B will take place as detailed under the condition of the said restoration With key 822 operated, due to the fact the saine relays in selectors B and C (not considering relay 207 controlled by calling device GD) are operated.

lin view ofthe last foregoing statements, the function of key 840 will be discussed here. It Will appear presently that the function of said key 840 is different depending upon Whether it is operated after key 822 is operated (as it ordinarily Would be) or if said key 840 is operatedivhen said key 822 has remained at normal. If key 807 has reina-ined at normal since calling lamp 804 became glowing, upon the Operation of key 840, an operative circuit Will become coinpleted from the Winding of relay 815, spring 816, spring 841 to grounded spring 842, causing relay 815 to extinguish' lamp 804 and light lamp 818 in the manner before described in reference to key 807. Also, retardation coil 802 Will be short-circuited through springs" 843 and 844, thus augmenting the current strength in Winding of relay 510 to its operative value, `whereupon the relays 302, 208 and 208 will actuate as be fore set forth in relation to key 822, wherein the calling telephone T is dis-.associated by relay 208 and applied to relay 316. How ever, the key 840 Would not, in practice, be operated until. after key 807 and key 822 have been operated and the Wanted telephone T4 has been signaled. Under this condition, key 807 having been operated, relay 200 is locked actuated as described. Then, when the key 840 is thereafter operated and retardation coil 802 is thereby ehortecircuited, relay 510 actuates and in turn causes relays 302 and 208 to actuate (relay 206 being already locked actuated). A. telephoniev circuit can now be traced from operators setiT8`, conductor 810, key spring 845, spring 844, conductor 801, conductor 511, condenser' 512, conductor 502, bank con tact 234, Wiper 221, conductar 236, ar1nature 237, armature 211, contact 245, conductor 246, armature 315, conductor 348, Wiper 327, bank contact 337, conductor 401, through the selector 2S, selector 3S, conuector CON, telephone T4, back through connector CON, selector 3S, selector 2S, conductor 33, bank contact 336, Wiper 326, conductor 349, armature 311, conductor 312, armature 214, contact 238, conductor 240, Wiper 222, bank contact 235, conductor 503, condenser 514, conductor 513, conductor 814, spring 848, spring 847, conductor 811, to operators set T8. It will be noted that retardation coil 250 is in bridge of the telephonic limbs attached to armature 211 and 214. Also, that the calling telephone T 1s ,disassociated l\4anifestly, this permits the attendant at G to converse With the called subscriber' at telephone T4 secretly so far as the subscriber at telephone T is concerned. Restoring key 840 allows relays 510, 302 and 208 to cle-actuate and re-establish the previously traced telephonie path between the telephone T and the telephone T4. Incidental to the restoration of key 840 (with due regard to the state of relay 208 because thereof) a circuit can be traced from grounded contact 340, conductor-341, armature 259, conductor 260, armature 323, con ductor 343, to the Winding of release n1agnet R62, causing` it to actuate and restore selector B, together With the consequent functioning of said D and G as set forth. Thus, When the attendant at G restores key 840, the trunk to said G is freed consequent thereto. 1f it is desired to listenin on the conversation, after the establishment of the telephonie circuit between T and T4 (by restoring key 840), Without (of course) restoring selector B as set forth, key 807 is operated before key 840 is released. Key 807 noW closes a circuit from grounded spring 848, spring 849, Winding of retardation coil 850, conductor 814, conductor 513, conductor 520, conductor 258, bank Contact 232, Wiper 219, armature 257, (relay 200 beino locked actuated conductor 321.

t3 ,l l 'd 7 armature 320 to the Winding or relay 3o),

said 351 actuating. Grounded Contact 340 being now disassociated, the traced path from said 340 to the Windingl of release mag net R62 is opened, so when relay 208 deactuates in re-establishin.Cr the telephonie connection between T and T4, no release of the selector B can take place, and the previously traced telephonic path through springs 809 and 812 will non: include the conductors 246 and 312 leading to the tele phone T4 due to armature 211 and 214 of relay 206 being attracted. However, upon restoring key 807, the described euerg' circuit of relay 351 is opened, causing the armature of said 351 to retract against grounded contact 340 and thereby re-establish the energizing circuit of release inagnet R62, whereupon the selector B is restored as before set forth.

Tt will be recalled that while the attendant at G was forwarding the call with key 822 operated,relay 208 Was operated and the calling subscribers .line was applied to the windings vof relay 816. Also, relay 207 .actuated and cle-actuated in effectuating 316 and augmente-the current-flow traversing the calling telephone T for lthe period of the impulse from thecalling ydevice CD. The fluctuations of current produce disturbances audible Ito the calling subscriber, indexing the fact the call ,is .being forwarded, and also the number of impulses in the series of impulses controllingit.

.From the foregoing, -whenthe call is completed from the called `telephone T to :the called telephone T4 through the selector C, relay 206 is .the only `relay in selector .B in an Operated condition, and .relay 330 is the only relay in selector C :in an operated condition.

Assume that after the attendant at G has i. started the forwarding ofthe call described,

through the agency of key 822 andthe calling device CD, ,itgbecomes desirous for some reason to negate t-he call impulses sent, perhaps because of an error on the part of the attendant .in operating the calling device CD. This restoring of the selector C and any successive switch thereto, is accomplished Iby operating the -key spring 836 to Aengage lits grounded cio-operating contact and 'so maintaining it for a period suiiicient to cause the slow-releasing relay (as 331 of C) of .the remotestswitch `towards the called line to de-actuate and cause the circuit of the release magnet (las R03) to be closed in a manner well known. The grounding of conductor 835 from spring '836 will hold relay 207 actuated Ibeyond the critical period of the slow-releasing relay last referred to. This, however, will not cause the restoration of selector B, so the ca'l'l can be thereafter re-for\`varded normally `by operating the calling device CD.

At the upper right-hand corner of F ig. 8

,two relays, and designa-tions thereto, are

shown as they are disposed in the pending application of Herbert M. Friend-ly (the present applicant) and Frank L. Fisher, coinventors, Serial No. 302,807, filed .June 9, 1919, covering an impulse transmitting device. Conductor 835 extends to armature 837. The armature 837, contact 852, armature 853 and grounded contact vSare added in adapting the said referred-to application last mentioned to 'the `present invention.

VAssume that thesaid connection is established from telephone T A.to telephone T4 by Way 0f selector fC and the selector B lhas been restored as set forth. If the calling subscriber replaces his receiver the conductor vl- 0,2 will `:become ungrounded under cont-rol upon relay 501.

of the connector CGN in a well known manner. Relays 330 and 206 will de-actnate as well Aas other `release-controlling relays attached to conductor -1-2 in selector A and pre-selector PS. A circuit to operate the remanner as set forth in the cited patent to Newforth.

It has been set forth in the foregoing de- L,

scriptions that upon the selector B attaining connection with the trunk including'rcpeater D, that relay 501 actuated. 'and also supplied lenergizing` current to the tclcl'ilione T, relays 13 and 210 being dis-associated. 5,."

Also, that relay 50-1, dependent upon relay 501, controlled the maintenance of selector B, selector A and pre-selector PS, so, if the subscriber at T replaces his receiver, relay 501 will cle-actuate,ffollowed by relay 501, whereupon said B, A and PS will restore, bearing in mind, of course, that relays 803, 8.15 and lamps 804 and 818 are dependent The release of said fl, A and PS is thus under the control of the calling subscriber under lall conditions, excepting the condition set forth wherein key 607 is operated after key 822, or key 84:0 has been Aoperated and relay 351 is operated, controlled by said 607, relay 206 being` locked actuated and relays 'C102 and 20S are actuated.

Under certain traliic conditions or methods of operation it is desirable to take tho last foregoing mentioned control from the calling subscriber and reserve it to the attendant at G. In accordance with incorporating such functions, switch-arms .32.1. 522 and i359 are introduced to permit of the functions described in relation to said (l. D. C, B, A and PS. Switch-arms 5321 and 522 are closed and.switch-arm 350 is opened. lt is manifest that the operative purpose of conductor 344 as set forth is thus negated by the opening of switch-arm 359. The relay 510 will remain actuated, regardless ol ythe condition of relay 501, as long :key 822 (or key 5840) is in its operated positiini. AThat is to say, regardless of the fact the calli-ng subscriber replaces the receiver` there will be no ground lapse von conductor 42, and, therefore, no release lof selector B orselector 4C can take place and the connection will be locked, to be unlocked only at the will of lthe attendant at 1G'. This `function would `be useful, for example, `where the origin of certain calls is desired, the connection being maintained to Apermit of tracing by o'mce attendants.

llt will be recalled that lin lthe last assumplll) Ifl

tion, the lowermost bank levelwas assumed to be the fourth bank level. In the condition about to be set forth, it will be assumed as the fifth level. A call will be traced. in view of this from the calling telephone T to the complaint department. The attendant at the complaint department will then transfer or forward the connection to telephone T4 as was done from the information department detailed before, ber of the complaint department is 4158. The figures will be assembled as in Fig. 10.

The arrangement shown lin Fig. is similar to that in Fig. 9 described, excepting that a selector Fis introduced and, therefore, an extra digit is required, After the connection is established from telephone T to the attendants circuit G, as before set forth, the electrical circuits are the same as described in relation to Fig. 9, bearing in mind, of course, that an entra link selector (F) free of affecting attachments, is intermediate of selectors D and G.

The trunk leading to selector D will be attained by the calling subscriber at telephone T as before, excepting that digits 1-5 will be called in place of 1-4, in view of the trunk leading to selector D (now assumed) terminating in the fifth level accessible to selector B andother selectors ofits group. After the trunk leading toselector D has been seized and relays 501 and 504 have actuated in the manner before described, an operative circuit can betraced from grounded armature 509, winding of relay 510, conductor 511, conductor 7 03, armature 702, upper winding of relay 701 to grounded battery. The lower winding of control relay 701 is iin-energized.

` 1f, now, the calling subscriber at telephone T manipulates the calling device 12 in ac cor-dance with the third digit 3, the relay 501 will be correspondingly7 ele-energized and re-eiiergized, since its windings are included inthe circuit including` the calling device 12 as has been traced hereinbefore. Relay 504 will maintain over the current lapses due to the retractions of armature 505.

The selector F will function as before set forth, responsive to the retractions of relay 701, resultant in the present instance from the retractions of armature 509, and cause the' wipers 7 06, 707 and 708 to be raised three steps to align with the third bank level, and there rotate automatically until an idle trunk line is found and seized through relay 712 actuating. lt will be assumed the trunk line seized is the one leading to the first set of bank contacts, and, therefore, wipers 706, 707 and 708 are resting on bank contacts 721, 722, and 7 23 leading to conductors 724, 725 and 726 respectively. Conductors 725 and 7 26 attach to conductors 801 and 814 respeC- tively.

The telephone num-` 1n this connection it will be noted that when selector F seizes bank contact setl 721, 722 and 723 and relay y803 actuates as set forth, a holding or maintaining ground (also serving as a busy guard) is applied from grounded contact 820, conductor 724 to bank contact 721. Furthermore, the maintenance of this ground condition on conductor 724 is dependent upon relay 501, so should the calling subscriber at telephone T replace the receiver, and thereby cause relay 501 to de-actuate as has been set forth, the ground maintaining relay 712 actuated will be removed by reason of the retraction of the armature from grounded contact 820. An operative circuit will then be closed from grounded armature 731,l armature 732, armature 733, spring 734 to 'the winding of release magnet Refi, causing the restoration of selector F.

t is manifest, now, that conductors 511 and 513l are in telephonie continuity with conductors 801 and 814 respectively, and that the link selector F intermediate between selectors D and G is conductive only and does not include legs or bridges. 1n view of the foregoing it is clear that the same equivalent circuit condition exists as regards said A., B, C, D and G, with selector F introduced, as set forth where it t F) was not included, and therefore, the operation of the selectors A, B, C, 2S, 8S, connector CON and repeater D in effecting a connection from telephone T to telephone T4 controlled from attendantis circuit G need not be reedetailed. Tt is, of course, understood that an exchange system would generally include a plurality of independent circuitrlinks as said A, B, C, D, 2S, 3S, CON, adapted to be variously combined as set :forth and that they would be so disposed as to enable a plurality of calling subscribers to sinniltaneously gain various attendant employes of the operating company, or in fact private attendants located on the premises of subscribers.

llhere a selector as F terminates a trunk leading from a repeater D as set forth, a third selector, as 3S', would not be connected from its bank contact sets, though, of course, it would/be feasible to connect them thus.

Referring again o Fig. 11 for the assenr bly of figures as organizerL in the relation aboutto be described, wherein a call is made from telephone T to the wirechiefs depart-- ment at attendant-"s circuit (l, and the call is then transferred or forwarded to telephone T4 under control of the attendant at said tl. The general object andthe fnnctioning in this switching operation is the same as that last described in reference to the assembly of figures as shown in Fig. 9. 1n this instance the trunk seized will include a repeater E, (in lieu of repeater D which could be substituted for E), the trunk

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