US1230996A - Telephone system. - Google Patents

Description

E. CLEMENL l TELEPHONE SYSTEM. APPLICATION FILED MAR.2`|I9II l 1,230,996, Patented June 26, 1917. l2 SHEETS-SHEET l.

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E. E. CLEMENT. TELEPHONE SYSTEM. f APPLICATION FIHED MAH. 2, 1941 'Patented'.mle 26, 1917.`

12 SHEETS-SHEET 2- E. E. CLEMENT. TELEPHONE SYSTEM. APPLICATION F'I'LED MAR- 2| 19H.

Patented June 26, 1917 l2 SHEETS-SHEET 3.

E. E. CLMENT.

1,2.'so,996;V

l2 SHEETS-SHEET 4.

A92 I OE Jl O00 2a f V y 30 ms Ooo@ x I9 0% w42 @200% V| E.. fa wZOO @2,6m l A OOOOOOW oo A oooooo Patented June 26, 1917,

E. E. CLEMENT.

TELEPHONE SYSTEM.

APPLICATION msn mm2, |9 1l Pawnted 11111526, 191'?.

' 412 SHEETS-.SHEET s.

E. E. CLEMENT.

'TELEPHONE SYSTEM. APPLIC'TION FILED MAR-2| 19H.

v1,230,996. Pamnmdqune 26,1917.

w l e. :REQ "Tn-"LIV E; E. CLEMENT. TELEPHONE sYsm.

APPLICATION FILED lAH. 2. 19H.

" Patented June 26, 1917.

I2 SHEETS-SHEET I- E. E. CLEMENT.

TELEPHUNE SYSTEM.

ArPucATloN min mm2. 19H.

Patented .I une 26, 1917. f

l2 SHEETS-SHEET 8.

Patented June 1917-. I x2 SHEETSQSHEET 9.

IVIIIHk M .MV TE: NTL EHA MSM D H Es CNU. .MF l EUG .Ll` fEEN TIC U DI DI, .A

E. E. CLEMENT.

TELEPHONE SYSTEM.

APPLICATION man ma. 2, 1911.

Patented Jim@ 26, 1917 E. E. CLEMENT.`

TELEPHONE SYSTEM.

APPLICATION FILED MAH. 2. 191x.

1,230,996. Patented June 26,1917.'

12 SHEETS-SHEET Il.

E. E. .CLEMNL TELEPHUNE SYSTEM.

APPLICATION FILED MAR2 |911.

1,230,996. Patented June 26,1917.

12 SHEETS-SHEET l2.

EXIL/710.

witness@ switch. The fizied contacts over which these wipers sweep in all the switches are usually referred to as'bank contacts, and in mass as contact banks.

The bank contacts of the first selector switches form the terminals of Second se- -lector trunks,'each of which is connected to corres onding contacts, that is to say multiplie in all the first selectors. At the right hand ends the second selector trunks `terminate at wipers of second selector switches, and from. the bank contacts of vthese switches the connector trunks are yAt lscribers lines are sliown, each with our taken, i-n multiple' asbefore, to the wipers of connector switches.v :The banks of these connector switches contain only line terminais, just the same es thegprimary selectors.

"the right hand end of Fig. 1 three subsubscribers stations connected to it in paralllel. These are party lines, so shown for the of sepurposeof illustrating the princil'lte of the I'ctiv m'ringing, which forms a pa sysggi. They need not'all be party lines however, nor is it necessary that the subo'lice, and it is` through the connector switches that the central office when calling `reaches the subscriber. Aa. line toi primary and connector switches are The connections of made'int parallel, ljust as are those of each line tmtliie several switches of either class.

Associated with each connector switch isi an auxiliary orringing selector switch. The

wiper""of this -switch sweeps over contacts connected to several ringing generators, each of which generates a particular distinctive the medium of'line relays at t character of current. At the several sta tions on la party linethe bells are designed and adjusted so as to respond selectively and exclusively, each to 'its own particular kind of curient only. Atthe last stage in a connectionfwhen the wanted subscrlbers' line has been picked out' by the connector switch,` and the ringing selector has been set so as to bring into service the proper generator, the wiper of that switch is then automatically connected through the -connector to the subscribers line to ring his bell. At

- all other times-.fthe ringing selector remains disconnected.

The primary selector switches 'are controlled by the substribers'in calling, through e central office which respond to the flow of current in the subscribersj'lines, and which when so energized guide 'and ,direct .the primary switchjwipers to their respectiveline con-- tacts. A calling subscriber therefore gains accessl to the first selector trunks inthe central olice by his own act alone. In order to continue the connection however, from the first selector trunk to the wanted subscriber, it is necessary to actuate a first selector switch, a second selector switch and a connector switch. The type of switch employed in this'system is electromagnctically driven by means of current impulses of predetermined number sent in predetermined groups," which move the lswitch wipers step by step over the bank contacts. These impulses are supplied, and the switches are controlled, by operators at the central office, who for that purpose are given access through secondary selector switches to the first selector trunks, whereby they are enabled both to receive their orders from the calling subscribers, by way of the primary selectors, and to send impulses to the first selector and succeeding switches, for the purpose of making the desired connection. The. secondary selector switches as will presently be seen, are initially responsive to the subscribers acts in calling. In fact, broadly speaking, their operation is the sa nic as that of the primary lector switch wiper to 'be guided and directed automatically to a contact in its bank which is connected to the first selector trunk in question.

In order to select and-transmit the proper impulses for line selection I provide each operator with a key-set mounted on a suitable desk, and having associated with it certain signals which guide the operator in the performance of her duties. The key-set in general appearance and arrangement is quite similar to the key board of an adding machine or typewriter, consisting of a number of strips of ten. keys each, numbered from one to naught in each vertical row.: One of the'signals associated with these keys is a calling lamp, which is lighted-mitomatically lthrough a primary selector switch. Observing the signal, the operator asks the subscr1ber for. the number wanted, and proceeds to depress the corresponding 'keysor buttons. She then presses a sepa rate Starting key, and groups of impulses, corresponding to the buttons depressed, will thereupon be transmitted through the key-set, through the secondary selector switch and through the first selector trunk 'to the first selector switch, causing the following operations:` (l) The first selector switch is stepped around tothe contact of a second selector trunk le ding to a second selector switch inI the thousandsy group corresponding' to the.

eoV

Lacasse igi't sot up; {il} the second selector ,rm/itch stepped around to select a connector tiuulc leading to a connector switch of' the hundredl-s group corresponding to the second lioit set un, (this particular' connector cont: ning terminals oi.' 'the line wanted); (3 and Ai?) the cminector switcl'i is then stepped y arourni in resiiionse to thethird and fourth 'grcui'is of impulses to piel; ont the terminals of the line wai'ited; and (Vithe asso ciatcd ringing selector having been set in response to the operation. ci the impulses7 the wanted` subscribe1"s bell is automatically rungl Y r Reference has been made above to thoun sands grr ips and hundreds groups of circuits'. This 'particular switching system is known 1 jieicentage trunking system. That is te my, the connection between any ict-ted by successive steps or subdivision. For enanipie, l., en csc .ange serving ten thousand subserib the second selector .switches would be divided .into ten groups, through one ot wlii 3 access could be had to the con nectors containing lines numbered from 1000 to` 1993, through the next, to lines numbered from 2000 to 395%9, and so on. Similarly, the connector switches in each thousands group wou` "l be divided into ten subgroups accord ginto their lnnidreds digit. 'Ihrough the flint off these subgroups,lines numbered from 100 to 199 'could be reached, through the second linee numbered from 200 to and soon. Obviously therefore, could bei had teeny desired lino by selecting tirs ser: ctor of the thousl in wh line innnber occui t a conf1 o 'Wb ich the yen the different groiiips (.fswitches e `coesplicated because of the. large l citar-silt wires enuiioyei finnish ibn it is i red between buttbetlieory quite simple, ough illnstratedin Ii..

one, of the 'subscribrs at the -1 has become connected in 'the manner stated with one of the subscribers at It will be noted after reading the forego ing, that portions of theapparatus andcir` cuits at the central office are common to all o1'` a number of subscribers lines, whereby confusion niight arise from simultaneous con nection of more than one lineto the Same, trunk, more than one trunk tothe same line, more than one trunk to the salue operator, or more than one operator to the saine trunk. Special provision is made however,. to-pre 75 vent this. At theleft of Fig. l I l'iavevindi-l cated what I call a primary distributing switch and a'secondary distributing switch. The first of these contains in its banks test .ing terminals of the primary switches or first selector trunks. It is actuated in re,- sponse to the subscribers calls, andal'ways. acts to select and start up an idle switch and trunk for connection withthecalliiig line. There is only one distributing switch for all the primary selector switches serving the saine group of subscribers, hence only one switch can `be started ata' time, and this'pre -vents more than one trunk being connected to the salue line. In going to the line, the action of' the primaryswitch is to test overy its bank contactsl until it Vreaches a contactf Vwhich has had its condition changed, due to current flowing int-he calling line. If incre than one line'is calling, ythe switch will stop 95 at the first one to be reachedT and thereafter 1 the distributing switch will Start another, primary selector to Search for the second calling line, whereby itis impossible orf` more. than one line to get on the sanietrunkf4 100 The secondary distributing switch pe 7, forms the saine functions with respect to the operators or secondary selector switches,l and is actuated also .inresponse to the sub'-, scribers calls, so as to Start only one seo` '105 ondary selector switch at a time for any one group ol' trunk-s. i N

Figs. 9 'to -13 inclusive show the' type. of.' unit switch used both for selectors and' con, nectors in this system. The mounting plate carries a pair ot `Contactbanks' on itsface." lin its general structure this switch is. the saine as 'that described and clalir'nedin ,myh prior. application filed 1T, 1910, Serial'f No. 561,804, containing also some features"V described and shown in Patent No. 977,536,` granted December 6, 1910, to Charles North. The present features of improve?" Y ment to be claimed herein, relate 'to'rtlhe". i grounding of the Wipers and the use Vof' an 120 additional wiper for row testing. In Fig, 9;; the upper bank .contains connective or` talking circuit terminals, and4 the latte-rV bank contains test terminals arranged in. a.

the several switches automatically re stored,` the connection is broken, and all parte resume the positions of .idicness diagraphically illustrated in Fig. 1.

marked r2 in Fig. .9 constitute a l'iorijzontal row with fiatffaceslaid horizontally-as best shown in ig. 10. All the rest ofr the ter#v minals indicated as c25-in Fig.' 9 and-'findii i vidually in line withc, c4 in Fig. 10, are 13h larranged inten vertical rows of ten airs of contacts each, each row being a ined with one of the flat contacts 02; loperating with the talking or connective terminals in 'the upper bank is a pair of connective wipers w3, fw* secured on oppositev sides of an arm fixed on the spindle, and pressing with considerable tension against opposite sides of the insulated extremity of said arm. By this construction, the rigid arm serves to perfectly aline the Wipers on the spindle, and their initial tension is transferred to the circuit terminals at the instant of contact in starting to travel up a row. Rows of testina terminals c25 in the lower bank are alinetl? vertically with and correspond individually to the connective terminals in the upper bank. It should be remarked that these terminals are not visible in Fig. 10,

which is a plan View, and in which the fiat terminals c hide those beneath them eX- posing only the 'talking terminals c3, c4.

Coperating with test terminals c25 is a pair of wipers 'w25 precisely similar to the wipers w3, w1; but to cooperate with the row test' terminals a horizontal rotary wiper "w20 is employed,`made in two parts, that is a solid bent anvil .spring, secured directly to an adjustable hanger carried on the spindle,l and arelatively light contact spring 'secured over the anvil with-its extension resting thereon under` tension. By this construction, the vertical adjustment of the wiper w26 as well Las its horizontal alinement sion of the sprlng' is transferred to the row test terminals c2 at the instant of con-r tact.

In order to insure successful releasing of all `the switches in the system, I provide a forward release through a special third coni ducto'r built up of the several links in conma of the release nection. To guard against separation of the vlinks before all the switches have released, I provide a. latch as shown in Fig. 11, which is pivoted on the inner face of the switch frame so as to engage and hold the detent dog m50 when it is actuated by the lever y magnet M3. In order to unlatch the dog` before the switch is again operated, so that the spindle will remain where it is set, I make it in` a vbell crank sha-pe, with its upper p arm engaging the armature lever m5 of the r`otary actuating magnet M'5 which is the first to be ener-` preferably of the 'type shown and described 1nv Letters Patent- No. 972,634, granted Oc- .tober 11, .1910, to Charles 4 vny standard relay may be adapted to this H. North; but

service.

.ranged as already explained.

are rendered positive, and the initial ten-- -another point by ,The operators keys employed as shown in Fig. 6 are.` built in stri-ps, are interlocking, and preferably of the general 'type shown in Letters Patent No. 955,134, granted A ril 19, 1910, to John'F. Cadell; but other standard interlocking keys may beemployed.

The distributing switches shown at S, S', L 2, S3, S7, S11 in Figs. 2, 5, 4, 8 and 9, are preferably of vthe type shown in my prior application, Serial No. 569,606 filed June 29, 1910, being single motion step by step electromagnetically driven switches with driving magnets mounted as a unit on a short frame secured to the contact bank. Each row or set of contacts in the bank is accompanied by a continuous solid return contact, .bridged with the individual unit contacts by the wipers as they pass.

The subscribers apparatus forms no part of the present invention except as it is included for completeness of description, and is of any usual or desired type.

Turning to the circuits, Fig. 21 illustrates Simply the principles I employ in the distribution of calls. 5-6 are primary trunk conductors terminating on wipers w3, w* of primary selector switch S1 containing connective line terminals c3, c4 individual test terminals c25, androw test terminals 026, ar- S is adistributing switch with two banks and two Wipers-ws, the first bank connected to cut-onv relays R13 in the several trunks, and the second bank to contacts in corresponding tip relays R1* in theseveral trunks. When subscriber A calls by closing his line circuit 1-'-.2 at H, line relay R is energized, and

battery B is connected to three circuits; A(1) that of starting relay R1; (2) .25 to c25; and ,(3) 264 to 02. R1 closes 39 to 3S (of an idle trunk), R13 and ground. R13 energizes, connecting battery to M and interrupter (Z1 to ground. M5 rotates S1 yuntil w21 touches c2 designating the row containing As terminals; R18 is energized through: B, 26, c2, w26, R1.S ,to ground. M5 Ais disconnected, R111 locks, and M steps up` S4 until w25 vreaches .021, whereupon R1 energizes through: B, 25, 025,112, R11',

ground. MG and R-11 are both cut off in-v stantly, the bridge circuit through R11 and R11v (previously opened by R13) is restored, R15 energizes through (i, 'w, c1, 4, R2 and ground, and R1* energizes 4 4 v w c 4, 2, A, 1, 3,03, 101,5, R12, giound.

through R15, 6y

is connected to battery. Mo

Circuit 17 8 of 'release magnet M3 is opened having previmisly been vclosed to ground whenthe switch started, but held openet R13. R14 puts battery on the second or test bank of R5 energizing its relay, connecting battery to stepping mag-- i switch forward until an idle trunk, with relay R1* denergizcd, v

net M, and kicking the is found.

'to the ii l each. liney circuit "1- maman@ The Stn ing swt t r t secondary' prnfern t 4 ntry' trn tity of tlm group ot tr the ident' nt' the numlines in knrrwn nn nt liner at onnn i.

ciples n the system n its entirety. 1 ,4. sirnplict r letnr i 'n'ttV from Fim. Q, mrd tnrtlltermnr lint v' :nt-- tions ofthe circuit arrnngnnmntn were nmdn. Fig' ring; in v 191g, l, is provc :i h n tin@ relay R and n gratuiti' rt uw E? wine mind also nnrglzed dinnnnnnntn the: tine rnlvsw conl'lects tbn tip und Steeve: uit thrfln ,t to its lnnltlilte bank: cmltnct in the primary l ergized and connector s-witans of its grnnp The attraction of the znrlnnturn 1' ni. thu relay R connects grnul'ld to the individual t ,st contacts 0f the prn'lnry swiuhns S42 yThel :tttractifm armata rn r11 locks th@ relay R on short Circuit to ground thrnngzr armature 'im of relay Rg7 Wh'ch prevent in terference by tlm nnbnriber ,in Case 11@ should move hisr-ecever hook.

Th@ line relays R are divided .into groups of ten and the rivndings nt 132mb. ,group are connected in nnllt'iple tu th@ Winning of a relay uonnnon to thegrnnp, which wlmn een ofthu primary switch through ttm anni ture r3", th ns desgnntng the group @t Unes falling, While the rulzty R designntns the Imrtinnlnr 1in@ in the grown` f Euch group of (me hundred. lines is nssnmed t0 have access for cnling [nung-'persas to ten yprlrnlrly'f selector `trllnksmy smh shnwn in Fig, 3, and to be accessible im," calling through ten connector switches Such its shown in, Fig. 4. T'i'lnn, enc-fh line has twenty contacts, ten .n p11-jimmy ten in the connector na-nkst The primary (11st rlnlting @witch S deter mines which trunk in the group of ten being idle shallA rnsponlc'l 'to any pzntnntm' (mit 1n its group of lines; und one `of these prnmrv distributnff' switchen; tlmrefnre required has 2t nur connects ground tn the row cnntzwt cnrweninnt nun nit the san- 5)? mnh :mn tnsrn'f 1' r own nasonnted in aantrof the ry ntnr 52m 13"urthermor, :mmm-ry' trnntngg Switch ,S2 in; Q in its lmnxks1 these v ally connected to y Switlylreg the Se Uf? null pnrpmsn in the Switnhes S2 snmmdnry Adistrl'tnnnin; switch n" :fnl grmlp, corr-@snond-mg con n C; 92 :unl

are nnnltlpld 'in thel ten, sw'ntnhes and. coni nnnter. ing; t0 the various semndnzry swtnl'ms Th@ cnntants 320 :tra not Innltrplert but nrw wired, dirent to the rnw sont-acts nf the, sennntlnry swimmer'. S8. Ntnnlmr une switch belonging to ncertnin group has its rst cfsfntztct s2 Wired to number on@` mw Contact oft th@ rSt rscondnry switch SB, its Second Contact 8 'Wired t0 mn'nbnr one row cnntzmt o'f the sennnd secondary switch S, anti, so on,

- Nmnbnrftwn @ther group hun itis r to mnnhnr tw@ rnw sont' Ondnry switch S85. wired tn nnnrber t second. sr nndnr'v wwltnn In an nx( 'n l contracts 5 of till@ tenth HW. tu nurnbnr ten row contat ts sW-thes S, 4

If ,in an excl'nmgn of one dumm-nd lines smntnnwns m11@ should umn@ in from nay'l group nf one hundrerl inen and tun Second ary selector switches S8 were provided, onerow contact in each switch ,S2 would be made ing connected to the wiper arm w of thevr switch S. When the arm 'w1 in rotating finds an idle primary switch S2 the relay R5 is energized in series with the relay R13 (Fig. 3) and opens the circuit of stepping magnet M, thus bringing the switch S to rest. The energizing circuit of relays RE and R111 may be traced battery B (Fig. 3), 31, 35, 36, 11151, R111, 38 (38 Fig; 2), s, ws, 39, R5, 40, T42, to ground. The energizing of the relay R5 ca uses the switch S2 to immediatel start to pick out an idle secondary switch S1. The switch S2 can be testing for the calling line while the switch S2 is testing for the trunk shown in Fig. 3.

The relay R13 acts somewhat as the line relay R', connecting battery to its individual test contacts in the switches S2.

It will .be noticed in the statement of operation hereinafter that the relay R13 is not denergized until the primary switch finds the calling line and the secondary. switch S finds the trunk connected to that line. By this arrangement all confusion is avoided regardless of which switch'performs its functions first.

Referring to Fig. 3, the relay R12 is the row test relay, and is energized when the wiper 'w22 finds an active contact, disconnects rotary relay R1B and in its place connects vertical relay R11. Y Y,

lhe relay R15 is used in testing for the individual contact as Well as a battery supply rclay'for the calling subscriber. When energized this relay disconnects the row relay R12. connects the relay R15 from the test wiper w25 and connects it to the sleeve wiper fw* in series with the cut-off relay R2.

Relay R11 is t-he tip battery supply relay and controls the release magnets M3 and M4 after the first selector switch S5 has moved off-normal. The relay R22 is used for opening the talking circuit while-the impulses are being sent to operate the outgoing switches. This relay also With R1l1 jointly controls the relay R11. Relay. R21 is the test relay having its locking contact 1" connected to the test wiper w1". Its circuit is,A

initially closed through the contacts offria-A lay 1 22 and foot springs 144 and 145. After the switch S5 makes its first vertical stig the circuit of this relay, is maintain through contacts of'relay R12 and test wiper The deenergizing of relay R12 dis- 4circuit of guard .lamp

w11? so long as this wiper Vencounters busy contacts which are grounded through other switches.

of relay R2*- whose locking contact r2 is connected'tothe bottom contact of relay R22. Relay R2a also closes circuit of relay R2. This latter remains energized until thecalled party answers or until the calling party hangs up his receiver.

1n case'the called-for line is busy, relay 'R21 will be denergized' by action of test relay R21. Relays R22, R27 and R29 all have their circuits completed to ground side of battery through test wire 200, contacts 02, w1", 147 1'212 to ground. When the calling party hangs up his receiver after failing to get his party, switches S4 and S5'are restored and ground removed. from test wire, causing denergization off any of the lrelays R21, R27 or R29 which happen to be locked.

The switch S is restored tov normal after the called subscriber hangs up his receiver or when the .relays R211, R27 and R21 are deenergized; and just before it reaches its normal position the wiper arm we" passes over a contact and closes the circuit of the w release magnet M12 restoring the connector switchS6 to normal position. Thus the vconnector switch Sc has a quick release if the called-for line is busy, and after the` called party answers a slow release by switch S7 which takes care of any accidentalV shaking of the receiver hook when the called' party answers.\

Referring toFig. 5 relay R31 is the row test relay and R311 the individual test relay. Relay R32 is the control relay and corresponds to relay R13 (Fig. 3). Relay R11 is the lsignal relay and pulls up in series with relay R42 (Fig. 3) after the primary trunk has found the line and the secondary switch vS1 has found the trunk. The operation of this relayV closes the circuits of the signal lamp L11 (Fig.6),the guard lamp L2v and Athe night alarm bell. Relay R31 is the listening' relay actuated by listening key LK. O eration of this relay denergizes relays R3 and R12, and closes circuit of listening lamp L. Relay Rw is the starting relay and is ener- 'zd in' series with R2 by the.. key SK.

his relay disconnects relay R33 andconnects the starting cam on the sending mai` chine to stepping niagnet M15. It also closes L2 and disconnects batterygfrom the first ve contacts over*y nect'iori the switel'iee Cam be r Dseril'n-:r has hung up his receiver er i..

ybattery to conteste lego" te 5x30",

Ju t. before s eeeiezi mii-rra@ emu Springe M5377 1.68 ple the circuit ef' reieziee restoring Switch S8 to its neri'rmi w `Relay R37 the trunk: einem rr. v also used for release in the @Ming liiiien. rid ie ub the @pewter fails to gel: e repense; Meer p ing the listening key. i

`Ths remy' .R37 is energized by k wi'ieli aise ententes relay RW .i reizl'ys being enerlyizeif :it @he l ne remove buttery eeril'ieetien fiom. me first erre contacts over which 'arm 'wem sweegl'e.. in trimr cells, such aie 'te wi' r chief, tell ben i ete., it :is eny :necessary te einem@ selector Switch., which with the i. ing maehil., requires only twe r the drum. The trunks of this dass are wired directly to certain bank contacte of the first selector switches and met te the eeiineeigcm banks, for quick trunk servirse. Aft r erm. 10830" passes the seemed eentaet the relay 1W is energized. and, up rates :ie befr In cui the ceiling' party bringe up his receiver before the @pewter were: reiey H is er fixed in. series witri resisst'm'me eeli fr when the operator prees n the listening.; kim which connects the keine t to the @per tors teleiihene set7 "lrereupeu elle pres the trunk Sturt hutten LH.

ef' Plezier, x'lmg'nets M"i4 und eus w the rel mi' switches le and bwiirii.

'm re tering imminente relay MH' whiuh. opens (.:lrelrits mi'. reirme 2 R3 und rehiy R35 to restore switch Si" emi any time rlmmg the iilllldin'.

it ed bjr the the marmer i, eee bei v Iig'. C, imri'iber une key' eil" 11min-t on eormeeteri. te the i' the Sending' lmehine Whieii trui'. y il'lxpulee :1t meh. rotatimi; rmmber twe kel-J to that which trunemits two ilrrpillee-1 mid S0 on te murlber teu key wiiieh tr nemiie ten impulses. .Each strip of ke communi `Wire connected to ene e'l'1teet, ef each keV in the Strip und lee )'.tdl ite proper Contact in ti baule; or the switeh. Si. The order in Whieh thee u, e rrmrigeei Exe t 'm'lemit impiilses in proper neme 'y SEOUUWS: At. the irst rotfuimr ei. the eend@ lum :im

the unite M.

fr i." im

epeln :i ing lump-hiru.; irme by ele u d, 'Nie mail@ einem* ebnen. three "'rn;:1ee It' 'i ezleh bmiir. "i wi'fh Ll 'wie r erfat" (me p in minimize @i i, (mitm @ver wiieii xvii m riy i. l 1

e ser-.semi

up efe, emi-- f el. swi. i' 'ifiteninel 'Le` en. ii, would require fws to complete the circuit of relay R6. It

'wiper c0810 is resting on inultipled contact 131 when relay RJ is energized, it will require only three steps of wiper 7.0.5" before the circuit of the relay R is closed. Vhen relay R2 operates it places ground on 218, 219, 7151, 31, M to battery, operating magnet M to step wiper ws to the next contact and thereby unlock the relay R5 which inturn denergizes relays R11, R2 and R2.. .The

operation of relay RG also places'ground on 21s, 22o, w81, 221, 71111 (Fig. 5), 122, 1.71, througl'i release magnet M11s to battery, causing the release of secondary switch S2 It for any reason. the secondary switch after it is selected fails to make proper connection with the trunk in Fig. 3 so as to relieve relays R13 and Rf", the' kick-of'switchI ture is optional, as in practice if switch S4 is left off normal lamp'L8 quickly attracts attention thereto and localizes the trouble.

Operation.

The subscriber at station A desiring aconnection lifts recelverR from hook H which bridges his telephone across line wires 1-2,

` 25 and 7112, while R3 connectsI grpund to row test contact c2 through 2G and 7131 and comi' plctes circuit of group lamp Land relay R1,

vthe former from B, l19,27, L, 28, 732, ground to battery, the latter from B, 19,029, R1., 30, 7-32, to ground. Lamp L lights, and relay R1 completes circuit ofQstepping magnet M to intcrrupter I for intermittent energization over Vthe path, B, 19, M, 31, 7121, 32, 7", 3,3, I to ground. Magnet M moves-'Switchs step by step until wiper ws'engages a contact .s connected to relay R11 (Fig. 3) of an idle primary selector trunk, whereupon relays R" and R1, (Figs. 2 and 3) are energized by current through B, (Fig; 3) 34, a5, 3c, 711-11, 37, R11, es, (as Fig. 2), 3,1118, a9, R2', 40, 7112, to ground. Relay R2 opens circuit of magnet M at 7', locks itself to ground through 7132 and completes circu1t of R11 over path B, 19Y 41, R11, 4Q., ,.53 and ground. Relay R13 locks itself to battery through 71121, 43,-' 7121, v44, and 34 tov B; connects battery to oneterminal of relay R12, through 34, 35, y71122, 45, 4G, 71152, 47, and48; and also completes circuit of rotary relay R12 through 7132 and interrupter I, so that this relay is energized intermittently, its circuit being; B, 34, 35, 71123, 45, 46, 71152, 47, 49, 50, R11, 51, T121, 52, 71112, I to ground. At each actuation of relay R12 magnet M5 is energized by current from B, 34,57, contacts 58 of foot step switch F1, 59, M2, 71121, ground, stepping primary selector switch S1 around until wiper 70211 engages row test con-y tact c2 whereupon relayjR12 is energized over circuit B (Fig. 8), 34, 35,- 71122, 45, 4G, 71122, 47, 48, R12, 49, w22, c2,- (Fig. 2) 26, 7131, ground to battery. Relay R12 locks itself to ground through 71122, connects test wiper 7.1.12 to sleeve relay R15 through 54, :"123 and 55, and shifts interrupter I from rotary relay R12 to vertical relay R12 at 71121, so that R11 Vis intermittently energized over the circuit: B, ai, 35', 7111, 15, 4c, 7112, 47, 19, R11,

56, 71121, 52, 122, I, ground, to battery. At cach actuation of relay R12 vertical magnet M11 is energized over the path B, 34, 60, M, 61, 71131 to ground, stepping switch SV41 up until Wiper w22 engages individual test contact 022 (Fig. 2) whereupon sleeve relay l 12 is energized over the circuit: B, (Fig. 3), 3435, 62, R12, 55, 71123, 54, w22, 022; (Fig. 2), 25, 7112 (of relayD R) ground to battery. Relay R15 connects battery to trunk conductor 7, by way of 7'121, 63, 64, 71141, 65, and resistance 7, and at the Same 'time opens the circuit of relay R12 at 7'112. Relay R12 opens circuit of vertical relay R12 and magnet M is denergized, which permits wiper to stop on contact c25, wipers w3 and w1 engaging contacts c2 Vand c4, respectively. Tip

relay R1A1 is now energized through subscribers telephone in series with R15. Simultaneously with the selection of the calling line described, distributing switch S2, (Fig. 2) is stepped around in search of an idle secondary selector, by magnet M2 in circuit: B, 19, 41, 66, 67, 68, 7131, GS), M2, 70, 7111, 71 Ito ground. Switch S2 continues to step around until wiper. arm c0820 engages a contact 820 connected to an idle secondary selector, whereupon relays R11 and R22, (Figs. 2 and 5) are energized in series, the circuit being: B, (Fig. 5), 86, springs 73-74 of operatrs 'ack J, 75, s rings 76-77 of foot step syvitc F2, 78, R32, 9, through Fg.3

into Fig. 2, 820, 708200, 80, 81, R11', 82, 71112 to attraction of armature 71113 completes the cir- Icuit of relay R2 as follows: B, to R2, 2213,

locks itself to bat- I art of the row test circuit and the

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