US1176715A - Telephone-exchange system. - Google Patents

Description

T. G. MARHN.

TELEPHONE EXCHANGE SYSTEM.

APPLlCAION FILED AUG.1?. 1906.

atented Mar. 21, EN@

3 SHEETSA-SHEET l.

Y fflllen: n

i. G. MARTIN.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION man AuG.1l.19os.

Patented Mar. 21, 1916.

3 SHEETSSHEET 2.

T. G. MARTIN.

TELEPHONE EXCHANGE SYSEM.

APPLICATION FiLED AUG.17,1906. 1,176,715. Patented Mar.21,1916.

TALBQT i3'. MARTIN, OF CHICAGO, ILLINOIS,

firten ASSGNGR, BY MESNE ASSGNf/IENTS, T

FRST TRUST ANI] SAVNGS BANK, TRUSTEE, 0F CHICAGO. ILLINOIS.

TELEPHONE-EXCHANGE SYSTEM.

Application filed August 17, 1906.

e i vented n. certain new :incl useful lm: provennntin TeleplioiieE-Xclienge Systems7 'cli the following is ai specification.

My invention relates to automatic or semi- :iuomatic telephone systems,L und especially to telephone exchange systems in "which the system is divided into districts-that is to say, in which the subscribers telephone lines are divided into groups. and in 'which the lines ci each group terminate at sub-central. or outlyii g stations connecterl by trunk lines .iitli a :nain or centrati trucking station.

My invention also relates more especially to distrir tcl )lione of this char noter in which the intox-natie welectioi'i of en idle trunk line running from the sub-centrztl station to the main or centra! station is :iccor plinliecl by inomentnriiy grounding the ceiling telephone line. l

Gene-rally stated. the object of my luren-- tion is the proyisiiian of an impro-red and liigrlily eflicient telephone exchange system.-

iilpecinl objects of any invention are t-le provision of m ans by wiicli lle attendant at the mein or cf trnl station of o district systen'i ci this character may have supervision aint-i control over Ythe automatic trunlf;- ingf emmrntus it i siil3-ccntral or outlying .ik trunlzing stat-ions; the provision of means lino; the

by wliirii tml trui"j L to normal condition any portion o' the auto matic trinking machinery it any sub-central or ou" ne; trunking station; ,the provision :ef-n.5 enabling;- the attendant at the on attend-:int at tlic moin or ecnig.; station may release or restore main or central trnnking station to know when ground is accifienta-lly established on cnf srritfcrs line running te any one of subcentral cr outlying trunking sta.-

nncl to then restore the automatic or switching machinery which was op' i xii.- tlie siilcentral .station by the nccirle grounding of. the subscribcrs provision o' means jfor enabling the :itt nflant at 'the main or central. trunki1 station todis-:onncct any subscribers line .from a. troni: line, whenever such connection brought about by the accidental i: riding of the snbscriberls line, and for thus preventing the. acciclcntal grounding of telephone lines from putting e correspond- Specification of Letters Pate. At.

Patented Mar. 21, 1916. serial NG. 331,022.

the sub-central stat-ion or stations;'tlie pro? vision of a releasing trunk between eecli subcentral station and the main or central trunlcing station, together with releasing switches located at the sub-central stations and selectively controlled from the central sta tion of the scid releasing trunks, whereby it is possible for nn attendant at the main or central station to release cr restore any trunliing connection which may have been established by the. accidental and temporary grounding of :1. sum'rilies telephone line, thus making' iinnessziry to send n trou- `ble man to tl'ie suive-entrai stations to store the ofi-normal switches; and the pro visions of certain details and features of im provi-.meut and combinations tending to in'- crense the general efficiency and improve the service of a telephone exchange system of* this particular character.

To the foireT infr and other useful ends, my invention consists .in matters hereinafter set forth and claimed.

Figures l and together represent an established connection tic-tween the' :subscriber #500 of @ne sub-central olliccl in the rict system and the subscriber #220 of second snb-centrai oilice'in the slime dis trict system, said system involving' the principles of my invention. The linc of the subscriber #G iliig. l) terminates in the line switch A of the ive--lnuidre sub-cen trel, which line switch, like all the switching apparatus in the system, is rontrolled by means of current from the battery B located at the main trunlring station and from which battery leads 'rmi to the various subo-entrai switch A is adapted selected one leading to. the repeat-er O1 (Fig.

2) From the said repeater Ct a main trunking station or outgoing trunk line leads to the two-hundred sub-central and terminates in the connector E. The said connector E is 5 also adapted to connect with any one of a number of subscribers lines and is shown in connection with the .line leading to the sul;- station #226. Bridged across the called line is the line switch A allotted to tl-.e said 1g line. Each sub-central station has a group of line switches which is controlled by a master switch. One of said master switches is shown at (Fig. l) and as represented is allotted to the lrehundrcd suocentral. As previously stated, the current is supplied to the various central offices by battery leads from a central battery B; hut provision is made for using` the ground as a return, and preferably, therefore, the positive terminal of the batery B is grounded at G. Fig. 3 shows more in detail the mechanical connection between the master switch and the line switch, and also shows more clearly the bank arrangement of the line switch. Fie'. fr shows in detail the construction of the master switch bank J.

in Fig.\ l is shown the apparatus H by means of which the attendant at the main trunlring oiiice may release the line switch A if he should desire. Said apparatus is known as an auxiliary release switch.

The substation may be of any suitable or approved type'. Said substation is equipped with means whereby the subscriber by removing his receiver 2 from the switch-hook 3 may disconnect his ringer i from its normal connection across the line, may close the primary circuit, and close the substation ground connection to certain points from which the necessary switching, `signaling and releasing apparatus of the system may be controlled. More particularly the substation is' of the. common battery type irlwhich the secondary circuit is a local permanently clim-ed circuit comprising the said receiver 2 and secondary winding 5 of the induction-coil 6. The primary circuit, when the switch-hook is up, is in series with the line and comprises the primary winding 7, transmitter 8 and the primary circuit springs 9 and 1G. The said springs 9 and l() are controlled by the cani arm 11 so that `when the switcli-hook is down the said springs are separat-ed and the primary circuit opened. The ground circuit is controlled by the cam arm .l2 through the medium of the ground springs 13 'and 14, and the ringer circuit is controlled by the cam arm 15, which latter controls the springs 16 and 17 that 'are included in'series with the ringer 4 Yand condenser 1S. The subscribers calling device may also be of any suitable design, but as shown'in Fig` l it comprises the s vitching impulse` trans- Init-ting device comprising the puslrbuttons 2U, the springs 2l and controlled, ely, by said buttons, the contact 23 and 2l against which thelsaid springs normally rest` and the ground post After the connection is established lthe signalingr is done by means of the signaling -lmtton 2o which is adapted, when pressed, to shift the spring 2'? away from the Contact point and into engagement with the contact point After a call has been made the switching apparatus may be restored by means oi the release springs 30, 31 and 32 which are adapted to be pressed into con tactal the same. time by the cam arm 33. The preliminary impulse attachment com.. prises still another cam arm 34 and the ground spring 35, which latter the said camarm is adapted to engage and through which u circuit is established with the rotary side of the subscribers line.

The line switch A may be of any suitable or approved type, such, for example, as the general type of line switch shown in British Patent No. 26,301 of 1906. Said line switch comprises, as shown in Fig. 3, the cutoff relay 35", trip magnet 36, release magnet 57, and the bank I composed of a number of bank Spring sets, only one set being illustrated, which set,` furthern'iore, is shown shifted 90 degrees from its true position about an axis parallel with the springs and passing centrally through the set. The set, as shown, comprises the springs 38 and 39, 4.0 and Ill, 42 and 43, and "t4 and 45. For opera ting the bank springs the line switch is equipped with a plunger 4G pivotally mounted upon the plunger arm 47, which latter is subject to the rotative tension of an open ating spring 48 about a pivot 49. The armature 50 of the release magnet 37 is normally controlled by a retractionI spring 51. .Said armature in turn carries on its end pivotally mounted the armature 52 of the trip magnet- 36. Said arn'iature 52 is normally controlled by the reti-acting spring The end of said armature is provided with an angled section adapted to so engage the plunger arm 47 that normallyy the plunger 4G is retained Within the channel 55 of the plunger Shaft 56, which latter is controlled by the master switch l". The individual switch as a Whole operates in general follows: 'Vheu. the subscriber rcn'iovcs his receiver :from the switch-hook tl.; trip magnet 3G is energized for a moment and the armature 52 attracted in order 'that the catch' 54 may discngage from the plunger arm 47; then the spring 48 rotates the plunger arm Il? about the pivot 49, thrusting the plunger 4G into the bank l. bronoht into use may be' restored by a n'xon'lentary energization of the release magnet 37, when the subscriber restores his receiver`- which release magnet then attracts its armature 50, and raises the armature 52 The plunger thus i'iii'ri i/-ririilions of the Side switch. Ars shown iii Fig; l, the vertical trunk lino con- ;hii-tor i() torii'iiniitezs in the Side switch ivi per VW? mi? the rotfiry trunk conductor lOl ti-i'iiiii'iiitii-s. ii iii the switch shaft ,g iiiz. which hitter, when the svitch is iiy inni? pfiiiiioii. in connection with thev iiiiii", iisiiri' i'iihiy 'Ji. hiit when the switi'h i ii'zisii iii-ii 10473 liv-iii voiiiphihfd hy the switch D.

'Hiv i'i-liiizitiir C1 iis wry milch like the reiwiiioii Theiifr iw (forti'iiii ilili'erances, him'iiiii'. whiih will he pointed ont. It is; ifriiiiihiii ii ith verticali iini iotriry lino iehiy )H0 iiiiii MU, i'iispritiiiiiy. [hv iiii'eiiiniizii rviii-fc IU hmi'igg tivo windings 112 :iiiii UR. iinii :i iioiv rhnoging roiaiy 1H. Thi? ifil'iiii gnwfingf through tini Siiiii i'vpoiitii diviiifiwi wi'tioii-i hy thi'- foniliiifii'ii' il-S iii'ii i. Tho ",irtiui iino 19h15' 'iix thu vertimii mainguet i :iiii :ihnihi iotzir'r inzignoz 12:?. The iiiitiiiii o' xiii i-'iiiii i'iirtiwii iiiiigjiiiit is to :iiii {hil :iii-,met :iiiii shrift Wiiwis :i Yiitif'nl i -fiiiif-iii. iiiii i ii i'oi'ii iiizigiivt 1225 ini- "i :haii :iiiii wn/wir@ :i rimini); or rotary' iini i'eifiy 1:10 il pi fito iiiiin'niit 123, whivh hitrir i iih initih. The Sido Switch :ifi4 is ich known thvy side switch ixiiiiiiii R24` 125. j :ind '2).'5. which 'ipii'i; :iw :iii rigidi; :goniivitiii :ind :iihipteii to :iswiiiii :mi: ni of thro-f imsii'ioih in thv nrvoiiiiilishiiiviit oi' rii'igiin Switching; operi rioni', that :ira weil known. Tho Iinv iihijcs U5# :ind i2!! (-iiniiiintiy vontroi the rohiini: iiiiigiiiil` i254. Viz-i101' ri-i'tiiin i'oniiitionsi th@ .wid iiihiiso iii:if,;nit 12H i5 oontrolhwl by thr private niiignit 1233. Lik(l the repeater, tho

i'iihilsii iii? nini 1 iziiiiimh:

lay 65, and line relay Oil?, "rut thv ud .isol'y relay is of Suflluinn; resi' down the current tu Suvh nu #dc-ii? pola; changing relay U5 und l uut become opei'uiivvly @ners sul'v uf mmimfiuu lwwwu will :nul 45 not; only ummm li lw= tion of thv nux'llinmy i' i lishes n guarding pwmnl Switch bank mnzu Ll ll l'm' 'his i1 tot' Switch luto the next" pub, m,

lt hns hcen z: uuml hui il@ www? .v im DCI (3l is in engagmnml with iw .uw mint 141, die said wpfr hw: long t0 always irmmulu mmv the con'xmrm plate lul-il. Tho mi Y 58 uml the dill'mei'ltizll Hfluy n u1" ll switch I" are euvvgized :il El i'u the said glmiding puteuiul i ut the Contact puin lff'l. Th1 'which the. Suid gumwliugj mix-ii., lished is as follows: from ilu, l HO to thf Velmse muguet Ill' ul Switch A7 thence ilxx'mlgh tis@ and 4H to lh@ html; fff'unmli lll, i then flows from ih@ said wnluc: Hum wiper Gl to the, Commun plate through the auxiliary whiff :7H :mf 152 of the (lifl'Qx-enrliul rel :1y Si) *Us lmu'linul Thv-Vemv, *will lh lelny 58 and 'the dill'm'er t ermrgizerl. the latter fo :mil 154 im@ frontaal. Huw limugh the motor nu Ynvt J slows friuli ground l hruugll nml l-. thmugh 'the snif?, mui# :Mg and through the intwuuw :mil 156 to the butif-,ry lf l Llmiugh bultm'y l@ gmini-, l nrgm 57 ihren nttrms lis; @i lug fh@ VuiQhm, @wel W) H m sitluu, 'Thu Suid ivm-,het wl; plungffr sh: ft 5? :mal Uw n; wiwi' (3]. Therefore, he :l mill Mtn-het wheel one step zu 1 swch wipm *il tu the m'v, lrini'imn mumgvmiem with the baul; mnnrif also nflvanves the plunger shun il. .fsu f ful operai iugj pemlrm t@ laila fmmlvr luf luie limi i fue Sailing. l "'xfiif; ,Uomini cfm il "N,

null,

"xl rieluy lb ,mul 1,0 the iS ma hummm 2%.-

zum;

u. tunis puke ground spying :wm 3i. Contact; pair me (ui-wlmi@ and am bmw ni; um w time Spf 40 :md 12., the u 7 and :sgn'izws M n n/l thmjg lease ma at the rf springs 163 and 164 are pressed into Contact and the vertical trunk conductor 10() is grounded from the repeater ground GB. The circuit over which this current is established extends troni ground (1 through the said springs 161 and 163, conductor 165, pole changing relay springs 16V and 167 to the Vertical trunk conductor 100. ("frounding thel saiil vertical trunk conductor establishes an energizing circuit through the vertical line relay .5125 oi' thc selector D, The energizing,r current flows from the rei/tical trunk conductor 100 through the side switch wiper 9G, Contact point 14.38 to the vertical line relay 93, thence tarough the said relay to the battery leail ifi() and through battery .l to ground (l. The said vertical line relay upon rnerfriziing presses the line relay springs 169 aiul 1T() together. sending a ilow ot current 'troni ground G through the said springs 169 aiul 170 and through the private magnet springs 171 ainl 172 to the vertical magnet S11, tlie'lu'e to the battery lead 140 aiul through battery l to ground G. The said vertical magnet. as is well known, ope ates toraise the shaft aiiil, therefore, the wipers of? and 5l() one step at a time. Since the vertical hutten 19 is pressed twice the said shaft is raiseil two stops. The same current that ciiei'ggiaes the vertical line relay (1;). of the rcpcater C passes through the whirling {Si} in thi" ilitlcrential relay (il` energizing sani fiiil'r-rrutial relay and causing the lat ter t?, wparat the sl'u'ing 147 from the spring 11H. "112e object in separatiiu:r the said spi-ingr-A i:l to destroy the circuit establisheil hetucen the vcrti lal and rotary trunk conductors 100 and 101 when the auxiliary relay (i6 eiiergizes to prevent the impulses olivia-eil to the vertical trunk conductor 10) ifi-oai passino to the rotary trunli conductor 101. 'Thr pmisage of said iiiipi'ilses, were the Sani springs 11T aiul 11S to remain in con-- would take place through the pole changing; relay (55, through the said (litlerein tial rrlay uprnif s 148 and 11T, auxiliary rel i a) sp 'ings 111V aiul 1165 to the rotary trunk vcinlurtor 10i. iV-lieu the switch shaft ot' the lf'si. selector l) is raiscil hy the first optaurina of they ycrtieal magnet 91, the normal 'post .irai 12'53 ot the saiil svlector permits the switch shait springr 102 to leave thc Contact point 115 anal oi-cali the eiici'giziiini circuit through the supervisory relay 10?. Saitl siipr-,rrisonv relay in turn permits the springs luf unil 15H5 to separate :intl destroys the line :Signal at the laiup 10T. The switch shaft spring: 102 upon leaving the said contact 1.475 engages the contact point 101 and thus con nccts the rotary trunk conductor 101 with the suie switch iviper 12T. which wiper is noi umili' iu cugiagg'einriit with the rotary line re- 'When the suhsrriher presses the roV` ary hutton :all hc preases the spring;r i onto ihe ground post lo and thus` grounds thek rotary line conductor 135. .1s a, result the rotary line relay .323 of the repeater C, as Well as the liil'erential relay G1. become energized. The energizing current flows from grouiulv il to ihr graad post :25, thence to the Spring :L anni to the rotary line conductor 131.3. huil( springt: and L2 oi' the line suitch .'.o ihr rotaryN line relay G3 of the repeater tlnfnce tiroug'h the winding itl oi'u the lii'erwiiiai iciay 121. through the pole rhango'n; relay 1pz-ings 127i aml 115 to the battery lead lli. thence through liattery l5 to ri-ouml '71"1.Y iziiig oi' the differ cntial ri ay 131 separates the springs 11T and 11.y for 'inc impose talrcaily described) of aepci'aiiinfy the established connection hetv'ecn the trunk coinluctors itland 101,. The rotary line relay il?, upon energizing presses thc .spring ii'i onto 4the ground spring 1ti. tlufirhy delivering a gijrouiitl iir pulse to the t tar; trunk coiiructor 101. The `'il impulsi;- iu turn operates the ictary line iii-lay uf ot the first selector i?.-

The current iow from gi'i'iuinl G at. the re pcatcr (j through tlnI above traced circuit to thc rota-y truiiii routlurtor 101, thence through the switch shalt springs 10;! and 101 to he title switch wiper 97, thence throinrh the rotar line rc1-.1y to the hat1 tei-y leali 1,10, and through battery l to ground (il. The rotary line relay 95 in turn presses the spring 17T onto the spring 109, as a i e-sult energixingr the private magnet :11. r[he current through the saut .magnet flows troia imm t at the said. fst-lector through the spring, to the private niag- 151" anzi li net SH, thiiue through the saint magnet to the hattffry tliii'uuirfh battery 1% to groan-il (i. Atc magnet then oper tites to trip the sul@ v, i tion` at uh' de switch iripcr til? n tinni thcy i engages the grouiulwi wenn it point 171;. A circuit lius established from ground ti to the rnntart poirt 175, siile Snitch wiper 51%) to the rotazji magnet '42. thence trom sani magnet and intern` spring .1751 to the buttery leaf 1li?. and through hatterv l to ground (l. .Laaiil rotary maiz/uct ih n rotutes the .shalt h first sico. azul a i the private 'viper Pu if iri'wn inte cngjacgfaient with the ariauuhwl contact paint the primte magnet if: is ijiii. ciziifrgineil hy a tion' of cui-rem from tin', saiil y waiinoleil coiitart point to thv private Kiper W1 through the harlnifbicase relay v le switch wiper 95%. rontari K iii ini. i Hite nuigiivt S11 to thc haltcrr kunt l tu, hernie through battery' 17% to unan l i thru luci ,"1 until iluE ff heron uiapnct "it then. o1? le; Y ,ua the siic sr'itr breaking the ener ing circuit for the rw ary inagni-ft tri' when the side switch wiper uff. 5172 carrics thiwip-ers .k lin The private ourse. m'iiiergizes, re.-

to third position -irffl 99 leaves the Conlne. peinf l As is well norm, if' there are no li my trunks n be passed over the rotary imafnel. il?. upon energizing the first lime. operi [li armature, of the In'iviite ningun-1 l :mil llme, releases the side ewieli 'fi-mn :iemand to third prefition. As Smm as ller ii mich ranches llie third poslliwn the file mritli pers` fil? mil 7 engage the funizu't minis l mili. N43s f1.0 that ille willing snmerilifr: .i .ended line condumorg 1U() :mil ll); m l@lill further e tended to Elie repufiiifr {"'i i'fulliermme, when the side swie wiper lhs engiiffes tile, grounded Contact ponia Sl i gmirz'ling potential iS established :it the private wiper il() from ground (2" for prom-ing the seized trunk line against inte? 'mense This.. Cir cuit from amid g3-wind l." 'xtigmlis te the Contact peint l., timmer rllrnngli (lie .side switch wiper bink-wle 'r relay 1F50 tu the private wiper 9G. Another effec# 'if tlm. passage of the eide smiiifli if.; :hlx-d ,'.jmslition is the lighting of ilse .s v lmnp US The ,.I'Cwit over wl 'ai' lmnp is en ergizeiL as eli mn, e

i um ille um( terminal l of lmefy llillriingjli uli snicl. lamp :1nd ihrfnip'li il' v'lle firiirli wiper Sffl (when flic irrite: ril poe ien) to the rotary marmo? f limer magnet te trie lmllery le. 1l l 1.4L mil llxrmlgli battery B in grofmfl l. The resistance (if the said lamp '103 is lrient tr prevent ille flow of Cnrrenl from affirming strony" enough i0 operati l 11e, the rotary lnzignel; 9L'.

The Semin l v'lerne-ul number be in the vertical i .il is again pressed tfvire :md he rofzy billion JC' mm1?. Vfl the verliefd milton ia pi. @ed 'wice flicverticzii line conductor il'.' is :ig/1i( i giaslmdei'l twice anvil the Vertical line relay' 552 of the repeater @irrspwru.ingl'r operziefil, Said through ille will .relay in trim repeals ille impulses to the,

Verti( l trunk Cnnilnrimr .100, whirli in'ipulees are (ln vieil to lxe repes'itrr (l1 for operating the 'Veriiciil line relu ill?? of Said repeater' and. also the ilrrrenuii relay 11i. .lie energizing Firmin ffii' @gwei'iiling Suid .relays at the repeater C fluire from ground lg :J the repener C. :is ^il"e:x1l il ribeil, t0 the vertical hunk runduefL/r 10i). thence llumigli the side mitch Wip Hi of the -.t selector D, Contact point 82., verliuil line 'Wiper 88, vertical trunk conductor 18.3 to the vertical line relay 109 (Fig. 2), ilienue through the Said relay and through (he. Winding 112 0f the dilerential 11i-luy lll im flic battery lead 140, thence Il; ougli bnltery il to ground G. The vei'tifal line re. 10i) Hymn .\y)(:r:xtiiig presses lie. springe lli .nml le? inhic rtaell ,Yliereln the ixmimef received if. Ll

mund-res Ir-1;' flagrmincl l..

springe .l 5,8 und imm inging relay spring 186` und theme to the Spring i537, romlufflm lill unil vertical trnnl mn` lil-5. The said ground impulees :ire @lirerled lo the Connertm' E for ,ipernting; the resti :znil 15)?, :side .swim-li wiper 2Q@ uwntar peiii.

19S, Vertical nmgnx'-t .lill lo lille buttery leed 140. thence through lmlery lli tc; mund (i. i The differential rela), *gli ifi" the, repeuer (l1, like the iliilerent'iil relay nl' l'ie re peuter C, enf-rfgiz in series ver. line relay llf'f ai ,epnialrfa nnfl 201') im' "yrfwjing ize itlirnnggli the poli.- rmmging i: *L exists lie'ween. the, "tary and Verheul mnflllclors 133 ar :i lsf-mn, lis K retiring the train ef: from e said trunk ii iiilnrfvr if lili@ einer. il`7 ..en .GS the subscriber preA es his: nihil l i ZU lie energizes the roi/vri line rela,y

Springs l??? anal 164 logjelilier pulse to the mieii' trunk wmilmfl me rirenits ilrem'lj' ileef'riiiefl The y pli: is then i'irertfnl in, the :rrpefir i' ig. 2) for enei'iiiiin le y line r .ll The energizing en" nl. fini efirl ro" line relay 311) ir. ezslublis from uw? iii in?, (ii at the repeater fr: the wie trunk um fluctor 101, thence rlnmrgli the Switch zmi Springs 102 and 104 nl: the first selector v, side, switch Wiper 9i", rontact point 3h52, rotary line wiper 89. rotary twink Concl 1 Ui 201. rotary line relay il() of A (Fig. 2), winding' 113 of me line 1 lay HL pele Changing relay prin f i i203 of the pole cimngirf; relav ll?. to ihr: battery lend 140, theme tlirf. li batiery il 11. o grrmnd G. lt will be matinee-1, :limi the energizing circuit includes the iliiferenriiil relay 111, which relay is enerfgl/ed by the impulses to the vertical or mmry man duf-.mrs l0() und 101 for separatiwf 1 1w springs 200 and 199 tn preven the transfer of impulses 'from ille rotary trunk fnmiuaer 134 to the Vertiezl trunk rmnluitor 1.53, The rotary line relai* wl per as above explained, mit the spring 1E:

girlie tu the. rotarv trunk winflmior i wpewfing the ro Y line ri er nl' 'ille m rtorlf, They im #Jr-mr lim relay .122.0 .slieel :.i-in grime-'13 G12 at the repeater Cl throaggh the. pole changing relay springs 155 "vul 15S, 'tina relay springs 186 and 2M.. nurtor pole changing relay Springgge4 2U? and i106 t-v the rotary trunk conductor lili5 rotary iinr relay 120` Windin 208 of ther dit'orentia. relay 193, througi the oacffbrif relay Springs 209 and Q10 to the hatt( thence through battery l to rotary line relay 120 on hetomif. presses the line relay sprii r .5 onto me ground spring 194, energi/iiugg ie private magnet 12". The energizing muri-n1 i* was through the Springs 1111 and 211e. "r n the private magnet 123, thence Ewen hack-bridge relay springY` "W1 and the battery lead 140, theme hrw tcry B to ground ("r, The ,a'irate ma* 123 when operated releases; thc eide vait-'gh of the connector from tiret tion. The side switch 'wiper Lz the. engages the Contact point 211i. and. the switch wiper 126 engages the wmtacf f Q13. The shifting o1' the 'Si-ie sfviiifui i 12T onto the. Contact point 21 au?. the rotary magnet for the fri-ri. I net 1*;17 bringing the former ander mi;

trol of the yertical line relay 11a. it u he understood that the iiii'ewentia rrlav 193 is energized each time that the iert'. ri or rotary line relays are energized, hei' the same energizing circuit: but tina er zation of said diifereut'iai relay is of no rensequence at this etage.

The thi1d\digit being t) the presses the vertical button 111 then the rotary button 20 onse. the vertical button 19 ten. time@ grani. vertical line conductor 1G? ten tirava. impulses are received by the vertical line relay 62 of the repeater' C and repeated to thc vertical trunk cornilueor 10'.) and received by the vertical line v the repeater (l. Said yertica i3. e repeats them again to the u i.; conductor 1233 for operatingy the relay 119 of the connectm` l. paid line relay becomes emeregiifeti at pulse, as already ciescrihm'l. a causing the Spring 195 to he prem; i the spring .191. Each time that the engagement of said spi-inve` occursv the .tary mag net 122 is energized hy a tion' t 'or t tl Spur i offs L ll rfi i tu the said springs 191 and 1`1` 196 and 197 to the side swat-,ii Wiper 122i. thence through the rotary raaf; rc1:

l w the battery lead 11th and tizroi to ground (i. The rotary n' thus energized ten, timea and t shaft and wiper;-,` rotated. 'fr-.r the Second level and inta rf the terminals oi' the anhstati .f l/Vhen the calling snbecrilier on tary button 20 he grounds the rotar), con- :i to; 131' and operates the rotary line relay (315s ol' The repeater C. Said rotary line wiay in turn repeats the impulse to the rotary transl: coming-,tor 101. operating the ro" tary line relay 11i, of the repeater C, said rotary liuc relay iu turn operating to ener the rotary line rc 120 ot' the con- ;:wtfa- The cnrrggixat "n of aaid rotary 'uur rei f o1 the connector E produces the fi E lon ot the private magnet. l 3 o; tin connector over circuits that, are alth?, substation i250() it toi lou tran-smitten temi; through the px imary niiuiing Y of the which anual to the, rotary line conductor lo. aef e tlu'ough the line switch bank f-prirrg' zic; and 4f?. to the coinhinser GS of the repeater C to the ycijcal truuk conductor 10?. side switch Wiper .frlof the Selector n'tacl point 182, vertical line wiper SS. :Lai trunk rondo 'r 155, cmdensrr 115 e rayman-r t. tlfiggf 25, rotary line con- '.ifS-lto the erin-denser 130 at' the conl, ringer relay ""6 and 551?,

i ,eine arnet wiper 1.) 'inl-act poil'rtinro tary line e. iper 11T norn'ma contacter atari' anrcoinincm NJxringer springe nue and ringer *222. mnrneer verluif.: -zzondxictmf 22 vertical normal ifrticai Eine wiper ,1H :me

itch wipt-.r 1:4, con-- nen trunk; conductor 133, conne; i 115': of the rcgmater til. rotary trank conductm 291, rotary lino Wiper 89, contact point'135 of the ii Selector D7 wiper '31', switch haft springs 10i and 102, rotary trunk coi'iductor 101, co. .or "il" at the repeater springs; 38

mi. fl t :ci t, r tact pcf and J of the line switch il, Vertical line e 'l eprng Q1. Contact. point 23,

to the transmitter S.

ion is estali- J mal after tl'aI roxnect Eine r tema from through battery E to ground (il. The en ergizing Circuit for the latter extends from ground to the release spring 3l), thence to the release spring 31 and to the rotary line Conductor 135` through the springs 13 and 42 of the line switeh A. rotary line relay G3, Winding Tt) olf the rlillerential relay 151, piller-hanging relaiv epi-ing '1.771 and 175i to the batteri.' leaol 11|). tlienee through bat tery B to ground (i. Not onliY ilo the line relays G2 andl (Sl energize, but the dillerential relay (il enr-wines aho. ,entre the windings 69 and T0 receive rui-rent in multiple. Therefore the ilill'erential relayY ,springs 213 and '241 are in oontart at the Maine time that n the line relays 6; anfl 4325 press the trunk release springs 2li'. azul in into eueageinent. A release circuit is thubl estahlisherl for the release magnet 3T of the hue sniteh A that extends from ground lli" through the differentlal relaiY springs '-ll and 243, trunk release springe All aurl 245 and Aprings 44 and 45 ot the line switch A to the release magnet il? tht-nr" te the battery learl 140, and through ba -ry l lo ground (l. The release magnet 3T then attracts its arma ture 5() (Fig. Ill, thrusting the armature of theI trip magnet Il() on the end of the plunger-arm 1.7. i

At the saine time the tablishment of the sain' release eirouit produces a deinergization of the auxiliary relay Gli 0l' the repeater t` through ground between the ground terminale G2 and G15 (Fig. 1),

It will be notieeil that Sinne the spring 44- of the line -Witt-h .t is4 rfmneeterl to gremial duringr the establishment et this release Cir-- ruit. the rontaet lil ot' the master switrh bank is also gonneffteil lo gro'ilnil, ll it should happen that, while the said contant is grounded the master ,switfh wiper (S1 passes onto the. u; irl grounileil rontart l`1 the ilil'erentiflil rela): 3l) will be energimetl the same the naiil vontari pointurere ronnerteil to niain batteri'. lhe only ilitllerN enre beingr that the energiz/ini circuit for said rlill'erential relay' ine-trail ot extending through the hiding lofi lo ground Gi as previously ilesrriheil. extends, through the winrlinrT 24T as 'l'ollimsfi from' ground GU' at the repeater t" and 'through the trunk release springs Q16 anfl l5 to the spring #lh trent-e to the rontart point lill. master switch wiper lll lo the eoninmn nuinbrr ill of the niaffler sn'itrh bank J7 then@l through the auxiliary relay 5S a: l uizuling "21T ol the ilill'erenlial 'relay 5 `l it; ln lattel'li' leail lei-). and through batteri' ll lo f frounil (il. The ene/rei i f ol the :li'lierenrial relay :39. ol eourno uf-rs the rurrgfixaA tion nl. the motor niagrzr. .'i'i' for operating the plulnienilmit 536, ily .'-x uuml. Furthernxore. the Sinni! of the relays liz/l :xml l r i and rotary trunl; minlurli liflll muil 'lill simultaneously, whereby the Vertical :intl rotar)7 line relays 109 and 110 and the (literential relay 111 aro energized al; the saine time. rTherefore, the trunk release sprl ign 249 and 2,70 are brought into eng: .e'en'ient tollen t 12 t* roil :251i differential relai* apri, 93:2 unil 251 to the battery leml 141). thi-nre through battery 1) to ground (l. The Saul hail; re. lease relar. ilu-retori-` iuierg'ixes, pre it springs 201': and :25313 into mntart7 al" i .e elul'gxiinY the 'leaai net ll'. Thr will releaee magnet 5T ther: allume lt annulla@ and is thus in reaflin: i the seleel'onsuitrh l) ruhen leab'e sprui: repeater t energim: the releafze n of the selectin Di btt faunes a alunrlaneonf-a grounding ol' the trunk eoinliu-,tois `1 Il :nul 131 in a well known manner, wherein.' lne vertical azul rnlarj,Y line relays' llt' :intl 1:30 of the eonnertor ll are enereiaerl at the naine time and :with the differential relay lll. Aa a renult the trunk' releaso sprin and 259 :fre Drought into montant while ine tlil' inn,

.ferential relay Winge 2:58 anzi 'W are, in.

The reult that the ,rele net 1'29 in energize-il, 'n r a How of rnrzeiit from gromul (l1L tfnougfl': the trunlf e springs :intl in the sa net 12S, thence through si u'mgnet i through the spi in fis 22T and to the hat ter)Y lead 1ML and 'through bat-tay 1l to ground The relents magnet nl' the. een nertor upon energizing* releases fue switch .shaft of the eonneetin.

The foregoing all oeemxr. while the releae ySpring-s 231 and 3i). are in engagement out is Soon the :said springe `zepxrate the line relays (5'2 aml (il of the repeater (7 a5; Mil as the differential relay (il nl said repeater de energize, whereby the energizing circuit for the release magnet 37 of the line Switrh is destroyed, at whirli instant the said line switch A is restored to normal eonzlition. Also. the groan-:l eonneetson to the trunk' romlurtors l0() and 101 if; intel-rainede so that "the line relays 109 aiul 11i! and the dill' terential relai' 111 of the repeater if" film (serontart.

furthermore the Qjrouxnl afi inwind! uw t;

ll @il trunk minlnctnrs 133 and 134 is broken. As a result the line relays` 119 and 120 and the differential relay 12113 ot' the conneetnr E th;- energ'ize, permitting the release magnet 12S at saiil ewnnectnr to deenergize also. All the switching: apparatus, is thus restored te nur mal rendition. ln case the subscriber at the sahsmtimi #220 iloes not answer after ennneetion umile, as described, the release of the switching apparatus occurs in the saine amnmfr. 1 `||rthern10re. aS soon as the Cnnnertor wipers 116. 117 and 118 break con mention with the bank contacts the energiaM ing :fireut through the cut-oft relay 2325 nt' the line switch .v\ is broken, so that the saifl line snitffh A1 lett in its normal mntlitinn. The ealieil suhseriher answers (after con- :wf-inn ie made `iiih his line,y when the nerim siile switrvh par :es to third i'insitinn, as already deerrihenl) hy removing his receiver i l freni the sn'itelrlinnk, thus causing' the primary eirifnit springs 2W) and 2161. to close he primary circuit and break the ringing' mrenii, hy permitting' the ringer springs 4" :mil to separate. The priniary circuit wunprisea the windings 262 and 2G15 of the haelt l fe relay '2131. and when the suhiher sniteh-hnolt up the said relay .ill energixes and the transn'iitter Q65 et the, snfstatinn #2:20 is provided with hattery ler talking. The circuit over which the saiil 1' current lon's extends from grounti` at he connector t0 the Contact point '1232, mense te the side switch wiper 126, Winding .3E the haelt bridge relay 264, ringer relay sprinrs 21h and Q17, side switch wiper 125, vanta-'gt paint 215. rotary line Wiper 117 te the rotary line eunductorli). thence through the primary winding 266 of the indnrtioncnil "56T, transmitter' primary circuit spring@ i160 and 261 te the vertical. line conilaetnr 2:24, thenee to the vertical line wiper 11G', enntaet point Q14, side. switch wiper ,'iiy whaling 26:2 of the back-bridge relay 25;, fiicrential relay springs 268 and to l ry lead 140, and through battery B un ,ii-,nud G. soon as the back-bridge relay 264 energizes the springs 269 and 209 are pressed into Contact, and as a result the wle changing relay 114 of the repeater C1 is energized. The energizing current flows from gruund G t0 the side switch Wiper 12H. t'lienre te the hack-bridge relay springs '2611 and` i209 te the Winding 208 of the diffen ential relay 195, tnenee through the rotary line relay 12), rntary trunk conductor 13sL *le the pole changing relay 114 nf the re theme through the dill'erential ny, 200 and 199 to the .vertical ntlnetnr 133, through the vertical 119, winding 192 of the diferential .rif-; 1243 to the battery lead 140, thence tnrwra artery t0 ground G.

in course, the pole Changing relay 114. of repeater (f1 and the line relays 119 and i., Negri a 125i of the Connector E energize in and the line relay springs 1513, 1111 and 211 are pressed into Contact, but .ritli nu result., since the energizing airmail for the ringer relay 231. is hifi/lien between theV zl' terential relay springs 228 and :2 i'. are/l the spring ,ay-ring L' if; prever.:

a?. aan

e spring a -liart-rmmit hetaeen vertieal trank rendu-@tors the line reime 1h51 :imi l are ei fieri. @ne spring' 202 inte ingu-nient rfi spring irrh ai the 1w-.eier (il eatal an ei'ierg'ixing rirrni, l'nr .flue pele chai relay (E53 nil the repeater C in series r'ii, line relaya 1U?) 1 i 111) el the reps-my* The energizing ai-enit ree es arri-at grennd (im through the springs r,V L winding 113 m the differential relay' 111 rotary line relay 11G tu tin` mtary r l: rondnntor 201. rotary line wiper Sil. 'siii Switrh Wiper il?, Sniteh shaft sprirgs 1x1 and 10da rotary irunl; minlnewr 14.11. mi dueter 14%", :with: fj; relay ,spi-ii 113 an 114. ilillerential relay springs if mi pole changing relay ii. .ierteai trunk new ilueter 10U, side zliwiteli wiper 9&3, mntaet point 182, vertical lin(` wiper rertirai trunk Conductor vertical line i., y 1053 of the repeatr 'i C1, yintling vi! if? et the tiifez eniial relay 111. t0 the battery lenti 117), thence through laatteiy E to ffronnd G. The energizing of the line rela e109 and 1m. since the pole changing re, y y 114 ism gized, produffes ne efeiiit: hut the ener, tion 01" the pnle Changing relay G5 at the repeater C supplies the Calling subscriber with talkingr battery Current when the pale changing relay sp1-ing 174 leaves the spring' 175 and engages the ground spring 270. A circuit is therefore established through the line relays '12 and G2 of the repeater C anti the transmitter 8 of the substation #500.

imi

arregle the repeater C, through the wintliiifg; @rif or the differential relay tt to the hzxtrrj.' h n llt), intl tliroiw'l matteiv l to grammi t'. The hinl relaye' t and "315 aw ein n zeri tur mg lhe how oll ,sant current and while the line relay springe 163%. [till anfl 17H are in commet; hat ainee lthe pole rhanpiiw rela; f3.3 is energized, and inw the pin j: li and ll are Separated, ainl as the .ap-linfa 271 :xmlL tion ol' Saul relay proiliffve` no etl'ert,

lt will he notieetl that hoth in the r la iter antl the reireater C1 the trunk h "nse springs flfi anti t3 lil in the former aral :l f, :ual 250 in the latter are in contrat, einro the line relays are energized hut the ie eirenits are not established heranir the flitferential relays (il and 111 are not magnetizwl and*y ther tore` there reepertire relezi wirr-nit springs 2423 and Jill anti :51 and i. :wie separate 'llie railing :mtl Palit-er? ariihrrs heim: rhin, prfiwi'leil with talking l'ai-r '-nrreiit ther roimiiiinxftte with ear-h rotary ,line rmnlluforer i :nel

' "ne relay ('f remit :he what if i peau-r 4 i# i fiintalnetl rnengj'z'ned, rotary "'1' t l W together with tling; T'' o. ll e tliilerenllal relay iria fir, 'firmite-'l through ground for a moment town the p'roiinfl points Gl at he '.ugraer l t anfl (il :it the substation. The el, rioting path extentie from non K through the pote changing relay :intl l'fllr thence thrwiigl'i the influer 1t the llitlerentill relay tit. aii'l rotarv lzw n?, te lh rotaia line waa/lz throw throifgif'l: the i'veazlf A Ill) 1t lhr^ fis, eiiinl heavier-:2 i

gi/r. separating 1hr e tet-mart the relraw oir-unit fip'inff@ elli anl There weiiltrl, tlwrel'orc` iiret. the ile' ciivlgilcatioh of the pole rhamring relay fi of the repeater Lw. rhanginj lili the piange tizing :force of said relay. The rethat. the vertical and rotary line reaiiil El venergy'im simultaneously, mg; the wrtifral and rotary trunk lo 10U and Jill, and closing the rase eirriiit through the release ot' the line switch A at the in lat the trunk release Springs 245 and the repeater C come into Contact. rr z ions to this? however, and soon as the f lf; rhangring relay delnergized, the line 'ya 10S,l and llt) ot' the repeater Cl also iirrgnie, einer: they are in the same circuit with the said pole changing relay. Therel ywe. grounding the vertical and rotary truuk conductors 100 and 101 causes, as in the repeater C. the energization of the vertiral line relay i) and the short-cireuiting ot the rotary lino relay 110 in series with the pole changing relay 114 is still energized, llie short-circuit exists between the tfoihxtl wint G at the repeater Cl and the :frontal point G* at the repeater C. The mit: of said ehortfrirenit reaches from frrmmsl fr through the springs 188 and 202, hrfrgfl the whirling .llf' of the pole chang- 1li and the rotary line relay 11() trunk conductor 201, thence to -taiy trank conductor 101. and through alle che jing relay springs 271 and :L am! throiigh the line relay springs 176 .mii 1M to groanrl GS. Therefore, the differential relay 111 at the repeater C1 loef-fmme ergizetl for the same reason deefrihetl in connection with the differential f ot the repeater C, and as a result the hanei relay 114 is (lenergizedf, since ,etai and 199 of the differential are serali-ated. At the same time the xmlal relaiY Springs 251 and Q52 come raw-, partly completing the trank The ilfinergization of the fion rel y restores the pole changril fr. whereby the ground contorexl to the line relayv ground l i l :unl the circuit is closed between f, y line relay spring Q04 and the rotary trium amllnetorl'll. Furthermore,attheinetant that the pole Changing,r relay springs @intl 903 rengage, the rotary line relay 11h if; renergrizerl, and sinee the current through the eindige? 113 of the rlif- ,.tifil relay 111 in a direction to augot' enrrrnt in the winding 112, serial lllierr ial relay remains energized for tirstiaie l ne; '"lheretore, since by the militanti-:amt energrivation of the line relays will aretl lll) the trunk release Springs 240 niet fal are hroiig'ht into Contact, the trunk f is established through the my 19) of the first-selector the ,anal lino relayerause the Simulroiznding ot' the vertical and rotary lnetors 133 and 131. Previoue` t0 ih vinding 1.13 ofthe differential relay 111,-

se zt, :mil Lw grumm Engis xrings :UM thm ffm; the,

ICL

position.

of ihe repeater energized and as a. re sut the springs 143 auf] "1114, :1S already QX- panod, cum@ inw mnnct. an( onergiz the supm'viory wfy "|03 uf Hw, fr* mter Causing the, supe? wy iight am! Humain so. Tim uizmflunt :1t '11110, main trunking' :emion on nmcrng the tmuMP- gibt :ai www, muws wnrfi; 2 mik .rfi Hm um: that has Limi bomma mfsukird.Since em'x Lrmk lim; has :1, Sapman@ seflusm' Assuming, for exzunple Lhdt the Munk Hm; ermiuing n ih@ s@ wml' w eighth truuk lending from: the ue switch 1mdk L contrary iuwhatvhasbcen :1S v med in the pr@ edng; the attendant. will upmwu the nlxlml'y release switch H bv px 'ng the m lary button H1 :h times. emrg'faingf e 'time the rotary maguc T over i' :from ground U through tho :1nd l'l'unlc con-lufor 1372? Lc the i Ynl T1v tary magnet '55. thm over Hw Confirmar 27% i() 'hv imita hmmm to ggwun fr?. ma guet, than um the pau@ 7G t0 T1? of fh:

:mul

lend HU. thancvEnough Thur mi( rotary lts; armature, mrd muws lle ' e5 the* apri winding; a smurf lense nr 553110! .iK-T 1' grml; d H rh m' The ro. i

magnet i7 e aub-central stations to restore any subsrrilad individual switches which may have leen operated by accidental and temporary gri'onniiingf ou the, corrospoinling subscriblinie.. The attendant at the main or ventral trnnliing. station can constantly bwrw the condition of the individual ,rwtrws at the sub-central or outlying sta tions. and when one is found oit normal as the result et au accidental and temporary f fjrouniiing of the subsorillens line, the at tend; nt can then select the trunk line which is thus temporarily tied up and put out of service. and may then cause the off-normal individual switch to disconnect from the said trunk line, restoring the latter to its normally idle condition. In each Case the automatic restoration is accomplished from iluy main or central station, and by lsimply piu/ting a ground on the trunk release circuit otl the oihnorlnal switch, the release, of course. being always initiated over the rele: i, trunk running; from the central etaiion to the i-;uli- =fntrai station at which the linozinal .switch is located. l do not, how iwi-:x inuit myself to this exact construction unil arrangfnnent, liroatlly considered my uwulxon is'. o1 coursea applicable to difiermn; )nel boils et releasing automatic switches. ik voor however', .l employ my central l "a: f-iili eriisory releasing or resteiiring :imafnaliis in combination with trunk rela: kfiwni attending between automatic u liche-x eti-:e n anti'nnutie switches and fr to.

dimi i claim as my invention is l. in i telephone exchange system, the

lnmhxoztion of' sizo"ii'i.liers lines terminat ai a sub-rriidral station, individual .ranches for the subscribers lines at the italien, one or more of which mariah trunk lines leading from the @tion to a main or central :luuk-img station, means for temporarily @ling i 1v calling subsoril'iers line to e the sponding individual switch t1; au?oniatmally select a non-busy trunk liso; a special release trunk running from the main or een ral station to the sub-central #tali-wn, ineens for transmitting electrical over said trunk, means at .sub-'central station for receiving said electr" #al innmlses ausl thereby selecting any busi' trunk line, and means by which the selei-fon ot' such trunlr` line automatically eff, the restoration of the olf-normal switch..

i?. ln a telephone exchange system.; the fainibination of a main or central trunki-ng station. subi-entrai or outlyingtrunking fftations. trunk lines connecting the main or ventral station with the sub-central stations, uli-xribrisi teiephoi'ie lines terminating at will sub-central stations` automatic switching maeliiiarry at the sub-central stations, a

hills special release trunk for each sub-central station, said release trunks extending from the main or central station to the sub-central stations, means at the main or central station by which an attendant may transmit electrical impulses over said release trunks, means at the subcentral stations for receiv ing said electrical impulses and thereby selecting any busy trunk line, and means by which such selection of a busy trunk line elfects the automatic release of the same from the subscribers line by which it is made busy.

3. In a telephone exchange system, the combination of a main or central trunking station, sub-central or outlying trunking stations, trunk lines connecting the main or central station with the said sub-central stations, subscribers telephone lines terminating' at the sub-central stations, automatic trunking machinery located at the sub-central stations and by which callingb telephone lines are automatically placed in connection With nonbusy trunl\v lines, a special releasin ,q switch for each sub-central station` said releasing switches adapted to select any trunk line, release trunks extending from' the main or central station to the said releasingswitiches at the sub-Central stations` 'which an attendant at the central 95 transmit electrical impulses ngi trunks to control the operations et sal-fl releasing' switches, and means by wim v1 the selection of a busy trunk line by a releasing switfzli automatically et 10( tents a da iefztion of the same from the subscriber line by which it is made busy.

4. ln a telephoruz eschanpje system, the eomi'iination of subsi' mers telephone lines, indiviL fil switches for said telephone lines` 105 trunk lines to be selected lily said individual switches, a special releasing;r i viteh common to all of said individual su itches, means rby whichfin attendant may cause said releasing switch to select any particular trunl- 110 line which is busy, and nic-ans by which such select-ion of a trunk line automatically effects a restoration of the corresponding offnormal individual switch.

5. In a telephone exchange system, the 115 combination of subscribers telephone lines, individual trunking switches for said telef phone lines. trunk lines to he connected by the switches with tl e telenhoue lines` a trunk release circuit 4For each individual 120 switch, a selectivo switch provided with means for putting a ground on any one of said trunk 'release circuits to release or restore the corresponding ofi-normal individual switch. a release trunk rnnning to said 125 selective switch. and moans tor transmitting electrical impulses over said release trunk to control the selective and releasing opera- 'tions of said selective switch.

6. In a telephone exchange system, the U0 rif.)

Combination of a main or central trunlring station, sull-central or outlying trunlnng stations, trunk lines connecting the main or central staion with the sulrccntral stations, Yers" tcleplmue lines terminating at tions, siiin-ieriherst inilirid.- l i l .i ual winning; switches at the sul1-rential sta.-

lions, repeaters at the sull-central stations, cer v mors at the sub-central stations, repeatiniear for selecting; any busy trunk lines and thereby releasing the corresponcl ing ell-nemici individual switches, release t?.

.mics extending from me main or central on to the said releasing: switches, and :nenas al.. the main or cenlral tion for enabling attendant te control elle scleclire and releasing'operalions el' said .fr-leas ing?, switches a telephone r combination of snhscril a wlephone lines, an indirie. h for 'ai eli-phone line, farnv'ir ,lines u: he selected by said iniliyr'lual si itrlics, said trunli` .lines less ".i nuancer lhan said telephone lines, an associated selective syilcli provided with. means for selecting any one oit sani trani: lines lia ing a haal; of eoulacls eorrespomliiig in mnnlier to the said. trcnlr lines. a wiper nel@ to lravel ver said contacts to selet the one corre ange system, the

spending to'a husy trunk line, a suitable' trunk lines and their in sairlvhanlr, means for first groiiindinf the sail! wiper and then instantly ri-fleasiit il troni engmfeinent 'with ny selected contact, and .cleans oy which the grounding of said wiper anwniatically ef` tects a release el' the ol'fnorinal individual switch by which the trunk line ccrrespondiup; to the selected Contact, is inaile busy.

S, In a telephone exchange system, the combination of individual swihfhes, an. associated releasing itch provided witlinieans for selecliiw' and Causing ihr .release ot' any ollaiornial n'nliyiilual switch. and. means for eli'ectingr the sel cl' releasing' operi tions .el sai@ i swireli. Y

` 4phone. exchange 9. ln a combination ol' ay plurali! v matic switching machine for selectingnony repeaters, an associated releasing switch vided with means for selecting and caussystem., the u: rei'zeaters. auto ing the release of' any oil-normal or busy repeater, and means for controlling the selcrtive and releasing operations of said asse ciaierl switch.

lll. ln a telephone exchange system, the combination of a plurality of trunk lines, means l'cr establishing connections with the said trunk lines, an associated auxiliary switch prfnirlecl with means for selccl'inij and causing the release or disconnection oi' any busy lrunl; line, and means for control ling the selective and releasing operations of any automatic auxiliary switch.

1l. In a telephone exchange system, the combination of a talking circuit including a trunk line, a supervisory lamp at one end oi" said trunk line, a supervisory relay associated with said lamp, a circuit through the said lamp controlled by the said relay, another supervisory relay at the other end of said trunk line, an energizing circuit includU mentioned relay, and an automatic switch l'or selecting said trunk.

ln a telephone exchange system, the

combination of a. trunk line, repeating relays at. one end of said trunk line,a selector at lhe otl'ier end of said trunk line, a* supervisory or oil normal lamp for said selectin', a supervisory or olinormal relay for said selector, a local circuit for said lamp, controlled li saiil oll-norinal or supervisory relay, another. siqiervisory or clnorinal relay associaterl Ywith said repeating relay and an. energia ing circuit for said first-mentioned supervisory relay mnu-oiled by said last-nieutioned supervisory relay.

w lil. In a telephone exchange syteni, the combination of a trunk line, re-peering re lays at one end ci' said trunk line. a selector at the other end of saii'l. trunk line a super i'isory or ofl'-1i0rn'1al lamp for Saidsclectozu a supervisory or oil-normal relay for said selector, a local circuitJ for said lamp, controlled hy said olf-normal or supervisoryV relay, another supervisory or olf-nornial relay associated with said repeating relays, and an energizing circuit for said inst-mein tionecl supervisory `relay controlled by said last-mentioned supervisory relay, said enel1A gluing circuit including both sides of the trunk line.

14. In a telephone exchange system. a talking circuit, an automatic` selector provided with a supervisory or olf-normal lamp, a local circuit for said lamp` an olli-nomini cr supervisory relay for said selector, said relay contml'ling the /ircuit ci said lamp, and an energizing ciniit including a portion of the talking circuit for said relay.

l5; In4 a telephone exchange system, a peuter provided with repeating relays. a` line over which electrical impulses are rcpeate/,l by said relays, a supervisory signal device at the other end of said line, a supervisory re ill) lou

i as

" im' wilaya: havng a spring or convrnvntlv connected to ground lele/rhone exchange system, a wrtical and rotary line con upm lla), "d 5 lf: a v normally connected mth 2u-ciers, and a pole-changing W :eneaten said pole-changing f ellen energized to shift the ff/minder from the non-ground .omnlcd pole of Said battery.

leplwne exchange system, are r, 'Aerrnfal and rotary line conductors a pole-changing relay, a battery pole ,grormded and the other lr connected With both line conhet".

preme line n l operating elay tlwretw er: ring inl endtc'lwe'` one pole ggrctunlcfl and ill' :milj: rcnniewtcd with on.: side phone line, the other k3 of 15 lm@ im@ nm'nmllyinen ed 'H I from oath the ground azul r n um l p()le-clla11glng relay adapted '1 enclffed to shift the rotary linc con im t'ne grounded to the nonwounded pole of the battery, a trunk realle and a differential relay, Said u circuit being controlled by *erential relay and the pole means; operated upon the ver trof il O

Yr telephone exchange system, a tion. Sub-central station., twoing the two statmls, nal Switches at the enh" film; for mrteroatically select/lng one or more of which arc ol means for enabling a central, met to release any olf-normal on the swii'th, lcctw Y phone echange system, a cem t snbcent1al station, two-'\\re nactlngig the two Stations. anto controlled by the Subscribers :'f'-|;.cax"' eelectng trunks at Elu; ,l one or more of which und means under the conaticr attendant for rcrmal switch.

wllene exchange system, a. l new@ a enlwfentral station, two ',f/onmfctng the two stations, zig mvitrhes controlled by thc L rl aubwentral station, a spe bmtch at the sub-centf'al sta ,e by which an attendant at ation controls said releasing and restore any ott-normal np; switch. .ln a telephone system, a central stacentr-al station, two-Wire trunks oor-fl n' t o stations, subscribers anw'natzf lfnnk-sclcctng switches at the Snbmama! el? non. a special trunk selector at :ulfu'cenrral station, a. special rele-aree fing said special switch with ztion, and means by which an elle central station controle said eleaee trunk for the purpose of nd- 'zel 4asmg any olf-normal trnnklng anton and 5e( tion, sani pole normally dem electrical connection ,n *einen tir-g the said ground conneenyn.

. l? 'il l, the at ,enter com: z telephone exchange system, alle f .Y tion lpg www@ mld x or a main or central trunkng

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