US2574903A - Translator for shifted lines and parties - Google Patents

Description

12 Sheets-Sheet l INVENTOR1 JOHN I. BELLAMY J. l. BELLAMY TRNSLATOR FOR SHIF'TED LINES AND PARTIES ATTORNEY mm2; DZOUmw Q J( ma Nov. 13, 1951 Filed April a, 194s NOV 13, 1951 J. l. BELLAMY TRANsLAToR FOR SHIFTED LINES AND PARTIES 12 Sheets-Sheet 2 Filed April 8, 1948 J. l. BELLAMY TRANSLATOR FOR SHIFTED LINES vAND PARTIES Nov. 13, 1951 12 Sheets-Sheet 3 Filed April 8, 1948 .ZmEn- DOM OZ-OZ- Y 11V i INVENTORI l. BELLAMY ATTORNEY JOHN l2 Sheets-Sheef 4 J. l. BELLAMY TRANSLATOR FOR SHIFTED LINES AND PARTIES wZmP ll E 0o.... um@

Nov. 13, 1951 Filed April 8, 1948 1\ vom mrw vm W f D L. R A m o N *|.L4 R N E OD E B m V T m I A Il? N Iollollollllol A m: HU n n Iv 5 IO'IOIOIQIOIOIIIOIIOIl OJIObIOIOIOIIOI wm m mam Emma F For;

w l l l l l l l l ||l OFDmEPmE NOV- 13, l95l J. x.. BELLAMY TRANSLATOR FOR SHIFTED LINES AND PARTIES Filed Apr-11 a, 194s 12 sheets-sheet 5 INVENTOR:

' JOHN l. BELLAMY A-rToRNEY Nov. 13, 1951 J. l. BELLAMY TRANSLATOR FOR SHIFTED LINES AND PARTIES 12 Sheets-Sheet 6 Filed April 8. 1948 E :mm

JOHN I. BELLAMY ATTORNEY Nov. 13, 1951 .J. l. BELLAMY 2,574,903

TRANsLAToR FOR SHIFTED LINES AND PARTIES INVENTOR! JOHN l. BELLAMY Nov. 13, 1951 J. l. BELLAMY TRANsLAToR FOR SHIFTED LINES AND PARTIES Filed April 8, 1948 12 Sheets-Sheet 8 rmTwO -OTmD INVENTOR: JOHN 1. r-:L'LAMY AT TOR NEY wm-uZOUm-w 20mm mnu/xml. JOMPZOU Am .UE um@ l l I x I l I D mmm 12 Sheets-Sheety 9 VOLLLLLLLLLL @1.1. Li. LLVLLlLLf com. L1. 1.1.1.2. up.

LLILLLLLLLL LLLLLLLLLH ,LLLLLILLHL'L LLLLLLLLLL mqnnnnnnninl EMU. 'LLVLLlLlLlLq 1.1141 LLLlLlLmO J. l. BELLAMY TRANSLATOR FOR SHIFTED LINES AND PARTIES LILiILLLlLLLLl mLLLLLlLLLLL iol 'mLILLLLLlLLLLl 0LLLLLL[LLLL[ LLLLLMLL'LL 5 @LlLLlLLLLLLL' @LlLLLLLlLLLLl l? INVENTORI JOHN BELLAMY n BY 40.1

ATTORNEY Filed April 8, 1948 Nov. 13, 1951 w www Nov. 13, 1951 J. l. BELLAMY l 2,574,903

TRANSLATOR FOR SHIF'TED LINES AND PARTIES Filed April 8, 1948 12 Sheets-Sheet 10 HIGH RESIS ANCE FIG. 8

N 7 a f E II{.II .'IIII2IIII D wlllals p 5 elsllgwgllgl INVENTORI JOHN l. BELLAMY ,/Agv'."

ATTORNEY Nov. 13, 1951 J. l. BELLAMY TRANSLATOR FOR SHIFTED LINES AND PARTIES Filed April 8, 1948 12 Sheets-Sheet 1l Nov. 13, 1951 J. 1. BELLAMY 2,574,903 TRANsLAToR FOR SHIFTED LINES AND PARTIES Filed April 8, 1948 12 Sheets-Sheet l2 F'ROM SELECTORS TTIS UNUSED FIOCCO) F'IUOUJ) NUOW FUOCO?) FIUUJ) P10003) P10007) UUTIP F10 |NvENjroR= JOHN l. BELLAMY FcJO ATTORNEY Patented Nov. I3, 1951 TRANSLATO'R FOR SHIFTED LINES AND PARTIES' John I. Bellamy, Antioch, Ill., assignor to Kellogg Switchboard .and Supply Companyi Chicago,

Ill., a corporation offlllinols Application April. 8. 1948, 'Serial' N o. 19,766'

This invention relates to automatic telephone systems. The general object of the invention is the production of; a new and improvedy line unit providing two-:War .Sor-vice ,for a groupof lines through tandem-related switching devices comorigine. primary and secondary subgroups inter@ connected by links spread among them.

A, Spooio object; is to provide a translator. arrangement enabling any Substantial traffic unv balance .anions the soi/oral primary subgroups to. bo Corrected by interchange amongthe pri,..-l rnary subgroups of; heavy: anic and lient-trat.-

linos, Without requiring the respective cali, numbers of tno interop nsedlines to be Changed..

.Another Specific object is. to. adaptY the trans.- la-tor arrangement to .handle intercept service for disconnected in vidnal lines and for disconnooted individual stationson party lines,- and to control the handling of calisltojP. B. X groups.

GENERAL DESCRIPTION It has been chosen to illustratethe invention as applied toa lineup-it serving one hundred subscriber lines, includingl individual' lines andl ten,- party lines, generally as discl-osedlin my co-.pendn ingapplcation for Automatic Telephone Sys;-v terne Serial No. 564,293, ledNovemberQO; 1944, now Patentl NoI 2,485,351, granted October 18;, 1949. Such a line unit employs primary, second-t.: ary, andv distributor groups ofswitchingapparatus ofthe type disclosed inmy: coepending ap-i plication for Automatic Telephone Switches, Se,

rial No. 524,816, led March 1, 1944, now'Patentf No. 2,490,665, grantedDecember 6, 1949.

The drawings Eigure- 1; Fig. `1 shows one of the one hundred lines (#I I) served by the unit, together with the individuall` line circuit of` such line,- and switching apparatus which may be employed as line-finding apparatus to extend such line, when calling, to an idle nder trunk (FTI). Such `finder trunk eX,- tends directly to a selector aparatusSLwhich may be operatedY in the usual mannerto select aA numerical group oftrunks, andv an` idle trunk; therein, such as-theconnector trunk-CTI;

t` claims., (ci. noa-i8),

The `individual linel circuit` ofV the. illustrated lineittI,Ifincludesline relay* IRI., lockout relay .I 02,`A

andcutoiirelay |03.

Primary switch I'A is oneof fiftyl line primary switches (see Fig. 10'). comprising a group served.

by common selectlmagnetsand select shafts is` one of a subgroupfofffve switches servingthe first iG-line subgroup, linesv II to Il). Primary switch IA includesl a hold magnet IM. and teni:

selective stackupsr of contacts, ot which stackup I (through which the associatedlinev #il is: reached-)- is one. The nine remaining selective staclpups-oi the switch are omitted for simp1icity;.

Primary switch IA is accessible to:li1f1esecond-A aryA switch- A2, andi thek others in theJ same secondary'- subgroup, byiway of the two-way line link LIA. Such link is reachedl through the illustrated stackup I of secondary A2, which hasinine. otherselective` stackups (not shown), each-of which gives accessA to a= line linkvextending to,V the corresponding one of the primaryisubgroups:

2'to'v0.

Fig. 1- showsvalso the-rst andy lastet ten subgroups ofy common equipment, liG'IiL and- TGIE).`

Subgroup=TG1t serves therst ten-line subgroupi (including the# illustrated linetial-Ii), while subi group TGO serves the tenthr subgroup'- of lines,` including line #00; Fig. 3; l

The equipment in subgroupr'llGli includes subgroup lockout relay H43 whichA isoperable-Vas hereinafter explained to` lockthe associatedJ tenilines temporarilyout of finder servieeunder cerrtainA conditions,` connecting relay I-2I, operable-` onlyduring line-iinderaction; for'connectingfth'eten local units leads I'- to-0 ofI the rst ten-line subgroup-to Athe-oo1nmonunits leads UI toUil;

tens-preferencerelay- I3-I-, which isoperable-both during line-nderaction and' during connector action to associate the-veprimaryrswitchesservi ingA the associated4 ten-line\ subgroup with' theL line controller of Fig. 5, Whichlcontrolsithe oper-- ationof the concernedfswitchesduring line efinder action and during connectoraction.'v Y

Fig; 1 also shows the units-selecta magnets;

which, control thea pr-irnary, select shafts.; servingf the line primary group of switches., Only;4 they,

first two and the. last, twol (UMI.` and UM2\UM9 and UMIl)J of( the-f ten, unitsfselect. magnets, aref illustrated inFig. 1.` These ten-magnets are-con trolled over. tenunitsleadsl to UI), vby tenunitspreference relaysUPl to URI),respectively.4

Fig. 1- also shows, Ithe rstvtwo, and. the, lasttwo..

ofthe tens-select magnetsTMl to4 TMawhie-h control'the select shafts of the secondary groupy oiiswitclies.` They are controlled?respectively"by'v l tens-preferencerelays |31 1:0440."

Figure 2 Fig. 2, parts 1 and 2, shows the connector CI. to which the connector trunk CTI extends, and from which the distributor trunk DTI extends to the distributor DRI of Fig. 3. Connector CI is one of the thirteenconnectors (CI to CI3) of Fig. 10.

Connector CI includes equipment for supplying transmitter current to the calling line, equipnent for recording the tens, units, and party digits in the number of the called line, 'and equipment for supplying ringing current and transmitter current to the called line.

The portion of connector CI, -shown in part 1 of Fig. 2, includes control relays 20| to 2II and the so-called talking condensers 2I2 and 2I3, while the portion of the connector CI, shown in part 2 of Fig. 2, inculdes the tens, units, and party registers TR, UR, PR I, and PR2.

Of the control relays of connector CI, relay 20| is termed a timer relay, in that it cooperates with the common timer 200 to release the connector CI at any time when such connector has been held for a predetermined interval seconds, for example) during which no eiective use is made thereof, such as dialing or conversation;

Relay 202 is a supervisory relay whose principal function is to reverse the direction of current flow over the incoming talking conductors when the call is answered;

Relay 203 is the line relay, being directly controlled over the calling line in the manner common to connectors;

Relay 204 is the slow-restoring release relay, controlled by line relay 203 to prepare the connector for operation and to maintain the connection;

Relay 205 is the so-called back-bridge relay, being controlled directly over the called line when the call is answered;

Relay 206 is the so-called ringing relay, which is operated under control of a ringing interrupter (which is part of the ringing equipment 24|, Fig. 2, part 2) at the beginning of a ringing cycle to place the connector in ringing condition, and which is restored during the so-called silent interval to permit back-bridge relay 205 to respond when the call is answered;

Relay 201 is the so-called switching relay, being controlled from the line controller of Fig. 5 to eiectuate the completion of the connection and to prepare for the ringing of the called line, in the event that the called line has been found to be idle and an idle connection path thereto exists;

Relay 208 is the so-called busy relay, being controlled from the line controller of Fig. 5 to place the connector in busy condition and return a busy-tone signal to the calling line if the called line is busy or if, for any reason, a connection thereto must be denied;

Relay 209 is the so-called tens-transfer relay, being .arranged to operate following the transmission and termination of the impulses, constituting the tens digit to prepare for the reception of the units digit;

Relay 2I0 is the so-called units-transfer relay, in that it is arranged to operate upon the termination of the units digit to transfer the circuits into condition for the reception of the party digit;

Relay 2II is a so-called chain relay, being included in the preference chain passing through contacts of similar relays of the other connectors. It is arranged to operate at the termination of the party digit to temporarily individu- ,Automatic Telephone Switches.

alize the connector CI with the line controller of Fig. 5.

Digit registers TR, UR, and PRI and PR2 (part 2, Fig. 2) are controlled over impulse conductors 223, 224, 225 to record the tens, units, and party digits in the called number. Each of these registers is preferably an electromagnetic counting device of the type disclosed in my co-pending application for Electromagnetic Counting Devices. Serial No. 493,312, led July 2, 1943, being illustrated as of the type shown in Figs. 21 to 25 thereof, wherein a single control magnet is provided with a hold winding (H), and with an impulse winding (I) effective to cause the counting contacts to close successively in a wave-like operation responsive to the successive impulses of a series. Obviously, the true party registers PRI and PR2 may be replaced by a single register of the above type having two independent sets of contacts.

Figure 3 Fig. 3 shows switching apparatus which may be employed to extend a connection, by connector action, from connector CI of Fig. 2 over a certain one of several paths to one of the one hundred lines (such as #00) as a called line.

The distributor DRI of Fig. 3 is one of the thirteen distributors of Fig. 10 (DRI to DRI 3). Each such distributor is a three-wire, twenty-point switch of the type disclosed in my previously noted application for Automatic Telephone Switches. Each such switch has eleven selectively operable stackups of contacts. of which stackups 2 and II are shown in Fig. 3. For selecting any one of the first ten outlets of the distributor DRI, the corresponding one of its stackups I to I0 is operated without operation of stackup II. When any one of the eleventh to twentieth outlets of distributor DRI is to be selected, the concerned one of the stackups I to I0 is actuated, along with stackup I I.

The distributor DRI has access to secondary switch BI by way of terminating trunk TT2. Through its illustrated stackup 0, secondary switch BI has access to primary switch OB, by way of the associated line-link LOB. Through its illustrated stackup 0, primary switch OB has access to line #00.

Line, lockout, and cutoff relays 30|, 302, and 303 of the line circuit associated with line #00 correspond respectively to relays IOI to |03 of line #Il (Fig. 1).

Figure 4 Fig. 1V shows the twelve distributor select magnets DMI to DMI2 comprising six pairs which respectively control the six select shafts (not shown) of the group distributors of Fig. 10. Magnets DMI to DMIO correspond respectively to the stackups I to I0 of any of the distributors, such as DRI; magnet DMII corresponds to the eleventh or switching stackup of any one of the distributors; and magnet DMI2 is an additional magnet employed to rotate the sixth selecting shaft of the distributor group in the opposite direction to that in which it is rotated by magnet DMI I. Magnet DMI2 is a magnet not disclosed in my previously noted application for It may be located immediately to the right of magnet DMII in Fig. 1 of such application, to cause the sixth selecting shaft to be rotated in the opposite direction at any time when selection of the eleventh stackup is not to occur. The utility of this arrangement is to secure invariablyl thefclosure or-.the distributor offfnormal con.

DGN Il, l2 associated Awith `the .sixthshaft of the mechanism. Oli-normal contacts DON l, 2; DON 3, 4.; DONS, 6; DON l, y8; and DON 9, |.0are `associated respectively with the nirst ve. selecting shafts of the distributor group. The oil-normal contacts of Fig. 4 are interconnected with conductors Vl .and 2 in distributor Vpair DON-to cause such conductors to be joined only when .one or another of Vthe rst five shafts has been moved oir-normal, .along with the sixth shaft of the distributor group. This `provision is utilized in the -controll'ofthe circuit operations in a `manner to. be pointed out subsequently.

Fig. 4 `fur-ther `shovvs :the circuit arrangement of #the units-sleeve connector USC 4and of the .tensesleeveconnector TSC of Fig. l0. These two sleeve connectors cooperate, during lthe setting up of a connection from .any `connector to the called line, yto connect incoming .conductor `CLS in `cablef552to the sleeve conductor of the called line, such as conductor SI l or S@` the sleeve conductor of lines #Il and #dit respectively. The hold magnet of USC is shown at 01, while the fhold magnet of TSC is shown at 92. These magnets.are'operatedover conductor S0 in cable 55.2 onlyrwhen the connection Vbeing handled `by the line controller of-Fig. 5 is one involving connector action, as distinguished from one involving line-finder action. Y Thelselective action of sleeve connectors USC and' TSC is automatically controlled in accordanceiwith .the designation ofthe called line,`for sleeve connector USCis an additional switch in the line-primary group, and sleeve connector TSC isan additional switch in the line-secondary group, as indicatedvin Fig. 10.

Figue .5

Fig. 5, consisting of parts 1, 2 and 3, shows the line controller previously .referred to. The line controller is temporarilycalled in for iinder action by any ten-line subgroup containing a calling line. It makes the necessary tests, and determines which switchesare .to be operatedto extend .the calling line to an idle finder trunk. It :is .also temporarily called in for .connector action by any Vconnector at which the called number has been completely. dialed. It then makes the .necessary tests, and directs the Vextensionofa connection to thecalled-.line It does thiseither .with or .without assistance y.from the translator V'II of Figs. .6 and l0 and .related equipment,dependingupon whether or not there areltranslator jumpers in place for the called number.

Through conductors in cables 55! to 55d, the line controller is connected as required with Vthe other equipment. Certain other conductors conneet the line controller with certainof theitems of other equipment as shown.

. ='Theline controller of Fig. 5 consists principally of-iifty relays, 56! 1101550. Of these, relays 549, 550, 50i, andf52-comprise the translator group, employed to control translation service; relays 503 to 501 comprise .the connector group, being operative duringeach connector action handled by the line controller, but 'not during nder action; relay v5(38 -is the lcommon start relay for finder vaction and for connector action; relays 509ftol i comprise .'acycle timer, .which is operatedeach time start-relay-.ll operates; relays 512 and `513 are .the clearout and .operate Yrelays usedduringnnder action-and connector action; Y

relays.` 1.5M. to. .5191 .comprise .the choice Lallottei.- which .responds to. each` operation of .start .relay 5mi .toshif-t. the .choice .to the next succeeding OneoiLthe secondary .subgroups Ato E; relays twto 525 .comprise ,thematching group, of ,which relaysZO to 5.213 control ,the matching insecondary subgroups Ato E respectively, .and reserye control relay 4525o1gzerates to reserve one. idle secondary switch of .each .category in a. subgroup,` until .required for a connection; relays 52.6 to 530 ,are primary test relays, corresponding respectively to switches A to E in any primary subgroup; relays .531 to 5,33 are 4test-control relays, .which Aactto control the secondary-switch test leads; relays 53.4. l.to 548 are the secondary test relays, `comprising five groups of three .relays,lo,ner.for each secondary subgroup A to E.

Figures 6 and 7 Eiss- 6 .andy 7 Sliovv the .translator Tl ,andthe resetfbus bers resnectiyelr Translator Tl come prises a single units ltranslator switch` UT, .and wetens .translator switches.. TTA and TTB.

ntstranslatorswitch UT (Figc) is anaddi-` tional ,switch in the .line-.primary group. as shown innig-10, which also. Shows that the tens trans-` lator switches `TTA and TTB of Fig. 6 are .addi-` tional switches. in .the line-.Secondary group. Magnets .604, S02, and ,6,03 are the hold magnets 0f ,translator switches TTA. TTB. and respec.: tively.

'Ihe resetbus bars of Fig. 7 comprise ltentons bus -bars 1Q] to U0, and ten units V,bus bars .1H to :729. connected respectively to tens. conduct.-` tors Tl to T0 Vand units conductors Ul to U0. E {ih switches of the translator act to extend za ltwogwire connection 4to any one. o f one hundred pairs. ;of terminals, onesuch pair foreach of the one hunlred line numbers.

Figure .9

Fig: 9- shows the equipment used to provide individual station interceptservice for party lines. Itincludes ten station bus bars ,9|'I` to 92D'connec'ted tothepar'ty registerPRZ `@Fig 2, part'l2),' a d-aseparate relay, such as 'l and B82 for each Party'lihleduirihestetige intrcbt' saftige!" l Figure v1 0 As shown in Fig. 10, a combined trunking and cabling diagram 4of the disclosed line unit includes' a group of fty line-primary switches divided into ten primary'subgroups designated -vl `to 0; a group of twenty-eight secondary switches divided into Vfive subgroupsdesignated A to thirteen connectors CI to CI3 (of'vvhich the connector Ciis shown in Fig. 2) and a group offthirteen distributor switches vDRI to DRI3. The rfifty. primaryswitches are served in common by select magnets UMI tovUMU, Fig. 1, through five lselect shafts (not shownfextending across the group; thetwenty-eight secondary switches are similarly served by select magnets TMI to lIMl), Fig. 1; vand the .distributors DRI to DRH :ares'erved byselect magnets yDMI `to DMI 2, Fig;..4,

AS indicated by their location in Fig. 10, the' common select shafts and select magnets of the secondary group.

Each primary subgroup contains five primary switches A to E, and serves a separate ten-line subgroup of the 10D-line group served by the disclosed improved line unit. For example, lines II to I0 are served by primary subgroup I; lines 2| to 20 are served by primary subgroup 2; and so forth. The ten vertical lines shown extending across the five switches A to E of any primary subgroup represent the ten subscriber lines in the corresponding ten-line subgroup.

As shown in Fig. 1 and in Fig. 3 (for primary subgroups I and 0, respectively) the conductor pair representing any line may be attached to the appropriate contact terminals of. the rst primary switch in a subgroup, being connected through the vertically extending, bare-wire bank multiple to the corresponding contact terminals of the other primary switches in the same subgroup. i Line-link cable 60| carries fty two-way line links between the respective primary switches and the bank multiples of the subgroups A to E into which the twenty-eight line secondary switches are divided. There are five line links for each primary subgroup of switches, one such line link for each switch.` These line links are designated LIA to LIE for primary subgroup I;

LZA to L2E for primary subgroup 2; and so forth,

to LOA to LOE for primary subgroup 0. The usual primary-secondary spread is employed between the primary and secondary switches. Accordingly, the ten links LIA to LOA, extending tothe A primary switches in the ten primary subgroups, are reached through secondary subgroup A; the ten line links LIB to LOB, extending to the B switches in the ten primary subgroups, are reached from secondary subgroup B; and so forth, to the ten line links LIE-LOE, extending to the E switches in the ten primary subgroups, which are reached from the switches comprising secondary subgroup E.

. Any primary switch, together with its associated line link, is employed both for finder action and for connector action. On the other hand, each secondary switch is definitely assigned to either nder action or connector action. The assignment arrangement selected is such that the odd-numbered secondary switches in any subgroup are employed for connector action, while the even-numbered secondary switches are employed for nder action. The rst five finder trunks FTI to FTB extend from secondary switch 2 in the respective subgroups A to E; the second five finder trunks FTS to FTI 0 extend respectively from secondary switch 4 in the respective secondary subgroups A to E; while the nal three finder trunks FTII to FTI3 extend respectively from secondary switch 6 in subgroups A to C. Since the unit disclosed is merely one of a number of similar units of the exchange, one or more stages of selectors are employed through which originated calls are routed to one or 'another'of the line units'according to the destination of the call. Cable 602 carries the thirteen finder trunks FTI to FTI3 to a corresponding number of selectors, while cable 603 carries thirteen connector trunks (CTI to CTI3) incoming from the selectors to the connectors. The unit herein disclosed is particularly adapted to cooperate with an installation employing one or more selector switching stages of the type disclosed in my patent for Selector Switching Systems. No. 2,400,530, issued May 21, 1946.

From the connectors CI to CI3, thirteen distributor trunks DTI to DTI3 extend, by way of cable 604, to distributors DRI to DRI3, respectively. As previously noted in connection with Fig. 3, each of the distributors` is a three-wire twenty-point switch, having access to twenty three-wire outlets. Of the twenty outlets of the distributor group, numbers 1 to 15 are employed, numbers 16 to 20 being unused.

The distributors have access in common to fifteen terminating trunks TTI to TTI5, extending by way of cable 605 to the respective oddnumbered secondary switches in sub-groups A to E. The assignment of the terminating trunks is such that terminating trunks TTI to TTS extend respectively to secondary switches I in subgroups A to E; terminating trunks TTS to TTIO extend respectively to secondary switches 3 in subgroups A to E; and terminating trunks TTII to TTI5 extend respectively to secondary switches 5 in subgroups A to E. v v,

Calls extended to the terminating trunks are completed, through the operation of the secondary switches to which such terminating trunks extended, and thence to the respective called lines, by way of line links in cable 60|, and primary switches in the concerned subgroups.

Detailed description A detailed description will now be given of the operation of the illustrated apparatus in establishing and clearing out connections.

A. Line #11 calls line #00 Operations involved in a call from line #I I, as shown in Fig. l, to line #00, as shown in Fig. 3, will now be described. Each of the illustrated lines #I I and #00 is shown as a party line by the conventionally indicated common connections extending from the conductors thereof. One of a possible ten substations on line #Il is shown at II5, and one substation on line #00 is shown at 00|. To make a call, a subscriber at a substation, such as II5 on line #IL removes Ahis receiver; waits for dial tone; and then dials the desired three-digit member such as number 7001.

Al. Marking the calling Zine When the receiver (not shown) is removed at calling substation II5, the usual direct-current bridge is closed across the conductors of the calling line, operating line relay IOI through contacts of cutoff relay |03. Line relay IOI grounds the associated start conductor ST, common to the ten lines of the first subgroup, and it also grounds the associated units conductor UI individual to the calling line.

A2. Tens selection TG1, through contacts of relay 1 1'1, the winding of relay |21', lower winding of relay 131, normally closed contacts of relay 13 1, thechained inner-lower contacts of the ten relays 140 to 131l nder-chain-in conductor F-CH-IN in cable 551, chain contactsB of transfer relay 501, contacts 2 of clearout relay 512, and thence to battery through the winding of start relay 508. Relays 1121, 131:, andv 508 `operate in series over the abovetraced circuit. Start relay 508 starts the line controller intor operation with results to be hereinafter described.

At its middle lower armature, relay |31 locks its lower winding directly to conductor F-CH-IN to maintain the above-traced circuit intact after .the control Ychain is brokenv at its lower contacts. The chain-end conductor F-CH-END is now isolated toA temporarily preclude operation of any further tens subgroup relays,` or of relay 50'1 Relay 13.1 connects common control conductors PA to PE in cable 55| to control conductors aV to E in the tens subgroup TG1, being the respcctive control .conductors of the primary switches 1A to IE inthe first primary subgroup. This permits test relays 526 to 530 in the line controller toy operate/Ain accordance with the busy er idle condition of the respective concerned primary switches., Additionally, relay I3j| closes a. circuit for the associated tens magnet TM1, to effect tens. selection in the secondary group of switches, wherein the first primary subgroup is thereby selected.

A3; Units selection When relay 12| operates'over' the above-traced circuit, it connects the ten units conductors to 0, associated respectively with the ten linesv of the rst" subgroup, to the comn'ion units conductors U1 to U0, which extendlre'spectively to units preference relays UPI to UPIJ.y With units conductor 1l in tensV subgroup 'I'GI grounded, units-prefer. ence relay UPI is operated over conductor UI through the illustrated, preference chain circuit. Upon operating", relay UPI closes a locking circuit for itself independent of the remaining Vrelays in thel chain, and opens: the preference chain to preclude operation of any further relays thereof forJ the timev being. This arrangement prevents two or more units selections from being made in casetwo cr moreflines inthe same tens subgroup arecalling at the Sametime. At its upper contacts, rela-y UPI closesv a" circuit for units-select magnet MI causing'units'selection to be accomplished in the primary` subgroup of switches, wherein line 1" ofthe calling' subgroup is thereby selected.

y A4.-` Tens and units selections locked Theefi'ected tensfand unitsselection are locked in` independent oi" the c'ontirnied` energization of li'nevrel'ay lllfllf, partlyv as an aid to furtheropera- .tions, and partly to preventl ifa-lise" or partially completednder actions-resulting from momentary bridging or grounding of the line.

Tile-L tens; 'selection is locked? in at the upper contacts of: relay |2'1fl which ground the associated start leadl ST' independent of line relay IUTI. The unitsrselection is locked in at the inner, upper contacts crumb-preference relay UP I, which lock therelay'to'units-lock conductorUL in cable 551, grounded. by contacts 3ofl stertrelay 508.

A5. switch operation Assoonfes thedescribedftens'andLunits selections have been accomplished, ground is extended to off-normal conductors- PSi-ON iny cable/55| 10 (throughoff-ncrmal contacts SON 1, `2 and PON 1. 2) to inform the' line controller of Fig. 5 that tens 'and units selections have beenv made.

Assuming that primary switch IA and secondary switch A2 shown in Fig. 1 are both idle, these two switches may now beoperated by the line controller of Fig.; 5 (in a manner to be hereinafter explained) lto extend callingA line #I1 to iinder trunk FTI.

The operating circuit for primary switch 1A is from ground applied to conductor' PA in cable 551 by the line` controller, and thence through contacts of relay 131,'primarycondctor VA. of subgroup TGI, make-busy contacts 105, and thence to battery through the winding of hold magnet I 011` of primary switch IA.

Units-select magnets Uli/II having been operated', the operation of hold magnet 104' results in the' closure of the illustrated stackup' 1- of switch 1A to extend the tip, ring, and sleeve con ductors of the calling line to the corresponding conductors of the line link LI-A. The initial-oper;l ating ground potential for hold magnet '1704? ls now applied, through the sleev'econtacts of stack up 1 of primary switch 1A, to sleeve conductors of the multiple `associated with the calling line; thereby closing an operating circuit for cutoff relay I 03- in series with lockout relay |02. Relays 103 and I0-2, accordingly operate, whereupon line' relay 101 restores because it is disconnected by cutoff relay 103. The" associated conductors S'I;` and If are thereby un'grounded', but this causes' no immediate response, for ground is maintainedzin each of these conductors (by relays 12| and UPI by the above-described" selection-locking connections.

TheA operating. circuit for hold magnet- 10B of secondary switch A2. is' as follows: from ground onI the associated control conductor CA2l (ground by the line controller as will be hereinafter eX- plained) through make-busy contacts 1-0'1f, lefthand winding of hold magnet 111B-, sleeve conductor: S of finder tr-unk F'II, backl andthenoe to battery through the illustratedv contacts, and resistor of the selectorapparatus S 1. Tens-select magnet TM1- hav-ing been operated, theoperation of hold magnet I06..resul.ts in the closure of the illustrated stackup I of switch A2,v to extend the conductors of line link-L1A respectively to the tip, ring, and. sleevev conductors of finder trunk FTI.

A- moment later, holding ground is placed ony the'sleeve'conductor of the established connection in thevusual manner by` the selector apparatus'SIf, providinga holdingv circuit for relays 102 and |03, and for magnets |04 and 106. Such holding circuit maintains the connectionafter the. line controller clears out, in a manner to be hereinafter described. The clearing out of the `line, controller causes relays V12-1, |3'|-, and UPI,v and magnets 'I-M-I andy UMI. tofrestore. The holding" circuit tor secondary switch A2` is from the groundy on the sleeve conductor of. the established connection, throughthe locking,- contacts of magnet |06 (the so-called off-normal stackup ofthe switch), the right-hand winding of magnet Hi8;y to battery.

A6. Selecting the called group Dial' tone maynow be returned to the calling line in.k the usual' manner; `through' selector' appa?- ratus SI?, informing the calling subscriberthat he may"commenceto dial. i

Upon the dialing of thehundreds digit 7 ofthe assumed? number (-70019 indexing tle disclosed A7. Preparing connector C1 for operation v When the connection is extended to connector CI, line relay 203 (connected to the incoming tip and ring conductors, through normally closed contacts of busy relay 208 and of supervisory relay 202) operates over the called line and closes an operating circuit for release relay 204.

At its contacts 8, release relay 204 prepares an impulse circuit for the digit registers, while at its contacts 1, release relay 204 applies ground potential to local conductor 2I6, thereby preparing locking circuit for relays 201 to 2I0, closing a holding circuit for registers TR and UR. At armature 4, relay 204 disconnects the associated idle-indicating battery-supply resistor and applies the holding ground potential to the incoming sleeve conductor S in trunk CTI, such potential being obtained through normally closed contacts of chain relay 2II and of timer relay 20I. The holdingr potential replaces the one removed a. moment later by selector SI in the usual course of its operation, and serves to maintain the connection intact.

A8. Setting tens register TR When the calling subscriber dials the second digit of the desired number (tens digit line relay 203 is restored ten 'times momentarily. Release relay 204, being slowrestoring, remains operated during dialing.

Each time it restores incidental to the dialing of a digit, line relay ,203 applies ground potential, through contacts of release relay 204, to impulse conductor 2I1. During the dialing of the tens digit 0, conductorv 2I1 extends, through contacts 9 of relay 201, and contacts 8 and 1 of relays 2I0 and 209, to branch conductor 223, extending to the impulse winding I of magnet 25|, of tens register TR, which receives ten impulses. Recording contacts I to 0 of register 'IR close successively as the impulses arrive, each preceding contact pairopening on receipt of the next succeeding impulse. Accordingly, contacts 0 of registerv TR are closed at the end of the tens digitvO, contacts I to 9 having reopened successively.

Off-normal contacts ON of register TR close upon the delivery of the iirst impulse and remain closed until the register is cleared out. The closure of contacts ON of register TR occurs with line relay 203 in restored condition during the delivery of the first impulse of the series. Each time line relay 203 reoperates thereafter during the dialing of the tens digit, a circuit is momentarily closed as follows for tens-transfer relay 209; from ground through left-hand front contact of line relay 203, conductor 22|, off-normal contacts ON of register TR, conductor 221, normally closed contacts controlled by armature 6 of relay 209, contacts 6 of relay 2I0, and thence to battery through the winding of relay 209. Relay 209 is preferably slow-operating by virtue of the comparatively heavy spring load carried thereby, and by virtue of a comparatively inductive winding. As a result, relay v209 cannot operate during the delivery of a series of impulses, for line relay 203 remains operated only momentarily between impulses of a series.

When line relay 203 comes to rest in an operated condition at the conclusion oi' the dialing of the tens digit, tens-transfer'relay 209 operates over its above-traced circuit. Upon so doing, it closes a local locking circuitV for itself at its contacts 6, at the same time opening its initial circuit. At its armature 1, relay 209 disconnects impulse conductor 2 I 1 from branch conductor 223 of register TR and transfers it to the similar conductor 224 extending to register UR.

A9. Setting units register UR When the units digit is dialed, the impulses delivered to impulse conductor 2I1 pass over branch conductor 224 (through armature 1 of relay 209 and its front contact), wherefore units register UR responds as noted in connection with tens register TR to record the units digit 0.

When line relay 203 comes to rest in an operated condition at the termination of the dialing of the units digit, units transfer relay 2I0 (similar to relay 209) operates over the following circuit: from ground on conductor 22I, o-normal contacts ON of units transfer UR; conductor 228, normally closed contacts controlled by armature 1 of relay 2I0, and thence to battery through the winding of relay 2I0. Upon operating, relay 2I0, at its armature 1 and associated contacts, locks itself to local conductor 2I6 independent of conductor 228; at armature 8, it disconnects impulse conductor 2I1 from units branch 224 and transfers it to party conductor 225, extend? ing to party registers PRI and PR2. At its contacts 9, relay 2I0 applies ground potential to holding conductor 226 local to party registers PRI and PRZ, registers TR and UR being held over branch 222 of grounded conductor 2I6. At its contacts 6, units-transfer relay 2I0 open-circuits and restores the locked tens-transfer relay 209, so as to enable the latter relay to be reoperated as a party-transfer relay.

A10. Setting party registers PRI .and PRZ When the final digit, party digit 1, of number 7001 is dialed, the single impulse thereof is delivered over branch conductor 225 to the magnets of party registers PRI and PR2 in series. Contacts ON and I close at each such register.

At the termination of the party digit, tenstransfer relay 209 is reoperated as a party-transfer relay over the following circuit: from ground on conductor 22|, olf-normal contacts ON of party transfer PRI, conductor 229, and thence to battery through the winding of relay 209. Upon reoperating, relay 209 does not lock operated, as its locking circuit through armature 6 and associated contacts has been interrupted at contacts 6 of relay 2 I 0.

A11. calling m the zine controller The line controller of Fig. 5 is now called in responsive to the closing of a circuit for chain relay 2II of the connector through contacts 5 of transfer relays 209 and 2I0, subject to the line controller being currently in idle condition. This circuit is as follows: from ground through contacts 5 and 8 of relays 201 and 208, contacts 5 of relays 209 and 2I0, winding of chain relay 2I I, normally closed contacts controlled by armature 5 thereof, chain-end conductor 2I8 (common to all connectors), chain contacts on the chain relays of all connectors, including contacts 6 of 83h14, HQS.

relay- 21H, chain-in conductor` of? cable 554, Winding of transfer relay 501 of= linecon? troller, normally closed contacts. controlled by armature.- 4` ofi-'relay 501, conductor- F-CH-END of'cabl'e 55|', chain contacts of relaysA such as 140 and I3l, conductor lil-CI--IN in cable-'551,1con.- tti-ctsV 3` of:l transfer relay 501, contacts 2V off clearout relay- 512, and thence to battery through the winding of' start rela-y 508.. Relays: 21| I., 501, .and 508i operate in series over` the above circuit.

At its armature 4 and associated contacts,` relay 501 locks itself to the orig-in` point of the chain (through contacts 2 of relay- 5|2'and-i-Winding-v of relay 508)` independent of conductorsF-CHs-END `and F-CH-IN incable- 551, While at 'its contacts 3*, it disconnects'conductor F-CH-'IN to preclude the operation oi' any orthe ndert control relays |31 and L21. (Fia 1). for the timebeine- At its contacts I, relay 5,01 adapts the line controller for connector action, while start relay 500 in itiates the required cycle of operations.

In the connector Cl, chain relay 2H, on ope erating, locks itself to the associated chain-'in conductor CI-Ij-INV at armature 5 and its front contacts, at the same time isolating its Windingv and chain-in conductor CHQ-IN from local chain# end conductor 2 |8 to preclude the operation for the time being of the chain relay in any other connector. At its contacts 2, relay 2j'l l locks ground on its upper Winding terminal `irntlepe'ndent. 0f Contacts of, relays 209 and 2in; to insure that, relay 2;I.l remains operated until restored by the line controller at its armature l and asso.- ciated contacts, it disconnects the normally appliedV source of holding ground potential from the incoming sleeve conductor and' substitutes ground potential over sleeve leadSL in cable 554', haying to do Withy reverting-call busy test; at its contacts 3 and 4,l it. connects Switching and busy relays 201 and, 208 respectively to switching and busy lead SW and. BU in cable 554,; at contacts 15, it connects conductor 'BL-IC and branch con:n `ciuctor 234, having to do with partyeline, inter.- eept. service; and, et. contacts; 8. and, .9.2. iteerineets steunde@ eondueter 'Il and U. Cable, Bitte. blraneh conductors, 2.3i, elle. 232A Q1', thea tens and un. s register Th and. UR., and thereby grounds. the selected one of the. tens conductors in.l cable 241 and the selected one of the units conductors in cable 248.

A12. Tens and' units selection upperwiedine et: the tens-erefeteeee teler-- A13, The Calleri. Zitate busy If the Vcalled 1ir.,1e.-#0;- 0.1" lie- 3.518,. busy/when called fact. iS, determined by the, line, een: troller of Fig. 5, which thereueon, grolllilisvoone. dreier Hlm @able 5.5.41, cleansed-recit through 0X1 Control. conductor CB1.

'through itscontacts 2.

A momentlater, when the line controller opens, conductor CII-IN in cable 55d incidental to its clearing out operation, chain relay 2H is opencircuited and restored. With contacts of busy relay 263i now open, relay 2H cannot reoperate` when conductor CEI-IN is reclosed at the line controller. Since switching relay 201 has not operated, no operating ground potential has been eX- tended to the sleeyeconductcr S of the distributor trunk; DV'IMi, Wherefore there has been no forward extension of the connection from the connectar Ci: toward the called line.

At4 its. contacts 2, busy relay Ets connects. the common busy-tone lead BT through back con.- tacts of relay 255, condenser 2id'. and contacts 3 relay 205 to the tip talk-ing conductor, therebytransmitting a busy signal: back to the calling line.v The calling subscriber is now expected to replace his. receiver to permit the established connection to clear-out.

A14. The` called line is die lf the line #00 of Fig. 3 is idle when called, the line controller of Fig. 5 proceeds to match a path thereto from any of the terminating trunks such as TT? and TTM of Fig. 3, andto set the distribue tor select magnets shownV in 4 in accordance with which of the paths has been matched. A s. suining that the matchedv path is by Way of terminating trunk TT? and line link LDB, the dise tributar selection` is such as to cause the illustrated stackup 2 ofiDRi (Fig. 3) to be selected` A15. Connector switching operation When the necessary connections have been efe footed` by the line controller, control conductors CBI andB of theswitchesBl and iiB (Eig. 3) arer grounded along WQ 'h switching conductor SW in cable 554.

The grounding of conductor B associated with primary switch 0B. closesa circuit, through makebusy contactsil, for holding magnet 301, where-A uponv the illustrated stackup 0 of such switch is closed having been selected by magnet UMR! (Eig, 1)..

Responsive to the placing of ground potential. a circuit is closed, through contacts. 3,66, for hold magnet 305, Where-y by the illustrated stackup d of swtchBl is closed, having been selectedk by magnet Mii (Fig. 1).

Responsive to the grounding of conductor SW inl cable 554 switching relay 261 operates, through contacts 3 or relay 2M. It closes a self-locking 951;? UQ @Qndlictor ZIB at its contacts 1; it un-V grounds. conductor 2,2 2 at its contacts 3 to permit registers TR and UB te clear :out: it prepares a circuit for ringing relay 206 at its contacts 5; it opens a point in the initial circuit of chain relay Ztl etitsbaek contact El; endatits contacts. 4, it extends the. grounded incoming sleevel conduce tcr, through contacts of busyfrela-y-Z, to sleeve conductor S in distributor trunk DTI, thereby elosirle e .Circuit for.. held magnet 3M Hold, magnet. 315.95 new Cleseefthe Selected Staekup 2 Qi the distributor-DB1 thereby extending- Cenduetors. TI R. S- ofV tr 1li., through the. back com pairs of stackup 2 of the distributor, to the selected terminating trunk TT2, whence the connection extends, as illustrated, to the called line. The ground potential on sleeve conductor S of distributor trunk DTI is now eiective to hold magnets 304, 305, and 301 operated, as well as to hold operated cutoff and lockout relays 303 and 302 of the called line circuit, such relays having previously been operated over the associated sleeve conductor S by the line controller.

A moment later, chain relay 2II restores responsive to the temporary removal of energizing potential from conductor CH-IN in cable 554, incidental to the clearing out of the line controller. With back contact of relay 201 maintained open, relay 2II cannot reoperate when conductor CH-IN subsequently recloses.

A16. Ringing the called substation Following the described operation of switching rel-ay 201, as soon as common pick-up lead PU is momentarily grounded (by the usual ringing interrupter in common ringing equipment 24|), at the beginning of the ringing cycle, a circuit is closed for ringing relay 206 from lead PU, through contacts 3 of units-transfer relay 2I0, contacts 6 of busy relay 208, normally closed contacts controlled by armature 4 of relay 206, and contacts 6 or switching relay 201. Upon operatin-g, ringing relay 206 locks itself to the normally grounded locking conductor L in substitution for pick-up lead PU, remaining locked over conductor L through the remaining portion of the ringing cycle, at the end of which conductor L is temporarily ungrounded to permit ringing relay 206 to restore temporarily before the next ringing cycle starts. If no response is obtained before the next succeedin-g ringing cycle begins, ringing relay 205 is operated again when pick-up lead PU next becomes grounded.

As the principal result of its operation, ringing relay 206 disconnects conductors T and R in distributor trunk DTI from talking condensers 2I2 and 213, and from the windings of backbridge relay 205, and connects them to the ringing circuit. The tip conductor T is thereby connected directly to ground, while the ring con. ductor R is connected, over conductor 233, and

- the closed contacts I of party register PRI, to

the selected coded generator leads GI of the ringing equipment 24|. After each ringing cycle, battery potential is impressed on the selected generator lead (by ringing equipment 24|), consequently on ringing lead 233, and thence to the ring conductor R of distributor trunk DTI and the called line. Any potential diierence, ldue to the condenser, in the ringing circuit (not shown) at the substations of the called is dissipated.

When ringing relay 206 is restored at the end of any ringing cycle, it transfers the tip and ring conductors of the called line back from the ringing circuit to talking condensers 2I2 and 2 I3, and to the windings of back-bridge relay 205 to permit'the ringing operation to be tripped re-- sponsive to the call being answered.

A17. Answering When the call is answered, the resulting closure of the usual direct-current bridge across the conductors of the called line permits back-bridge relay 205 to energize over the called line, through i the back contacts of armatures 2 and 3 of the restored ringing relay 206. At its back contacts I, relay 205 open-circuits and restores units-transier relay 2I0. At its contacts 3, units-transfer relay disconnects pick-up lead PU toprevent Cit 16 subsequent reoperation of ringing relay 206, and at its contacts 9, it ungrounds hold conductor 226 permitting party registers PRI and PR2 to clear out. The opening of ofi-normal contacts ON of party register PRI open-circuits and restores'tens-'transfer relay 209.

As a further result of its operation, back-bridge relay 205, at its contacts 2, operates Supervisory relay 202, through contacts 9 of busy relay 208 and contacts 1 of release relay 204. Upon operating, relay 202, at its armatures I and 2 and associated contacts, reverses the direction of ilow over the talking conductors `of trunk CTI for whatever purpose may be desired. This operation is utilized in many systems to operate call meters, to give supervision lat the switchboard of a calling operator, and the like. l

A18. Clearing out the established connection When the conversation is terminated, and the subscribers have replaced their receivers, the established connection is cleared out as will now be described.

It may be assumed that the called subscriber replaces his receiver first, whereupon back-l bridge relay 205 restores and permits supervisory relay 202 to restore.

When the receiver is replaced on the calling line, line relay 203 restores, followed a, moment later by the restoration of release relay 204. Release relay 204 is adjusted to restore reliably in spite of the self-locking circuit through 2I1 and contacts 1.0i such relay, as previously discussed. At its armature 1, relay 204 removes ground potential from the local holding conductor 2I6, thereby permitting switching relay 201 to restore. At the front contact of its armature 4, relay 204 disconnects ground potential from the sleeve conductor S of the established connection, thereby clearing out selector apparatus SI in the usual manner, and deenergizing the cutoi relays (I03 and 303) and lockout relays (|02 and 302) of the calling and called lines, and hold magnets |04, I06, 304, 305, and 301. By these operation-s, the entire connection is broken down. The connector CI is again marked as idle by battery potential applied to the incoming sleeve conductor thereof through make-busy contacts 2I4, and back contacts 4 of the release relay 204.

B. Reverting call on party Zine #11 The way in which reverting calls are made on party lines will now be described. It will be assumed that the subscriber at substation I I5 (substation 5 on line #I I) desires to call another substation on the same line, substation 0, for example. For this purpose, the subscriber at sub-` station II5 removes his receiver; waits for dial tone; and dials the directory number (7110) as' signed to the desired substation; replaces his receiver upon hearing the busy tone which is re-l turned by the connector CI; waits a sufficient interval to permit the called substation on the same line to be signalled; and then removes his 2), in which connector, relays 203 and 204 operate as previously described.

When the tens, units, and party digits (l, 1,

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