US1356639A - Telephone-exchange system - Google Patents

Description

A. E. UNDEL|.. TELEPHONE EXCHANGE SYSTEM. -v APPLlcATloN FILED Nov. 14, 191e. 1,356,639.

A/ben f. Lu//me/ by A ,y.

A. E. LUNDELL. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED Nov. I4, |916. 1

Patented Oct. 26, 1920.v

2 SHEETS-SHEET 2.

/MI/ena/f.- Alben L ande# n Nir E n r ALBEN E. LUNDELL, or' YoRir, N. Y., .assrGNoR To WESTERN ELECTRICv Y COMPANY, INCORPORATED, or NEYwYoRE, N. Y., A CORPORATION or NEW Y YORK. y

TELEPHONE-EXCHANGE sYsJTEM.

Appuauoii mea Novemberm, v'1916. serial No. 131,203.

T 0 @ZZV/whom t may concern Be it known that I, ALBEN E. LUNDELL, a

citizen of the United State s,'residing atNew Y change systems, and particularly to means for applying ringing'current to .the called Y line. It has been found in practice that the number of inal switches is greater than the number of certain v of the intermediate Y' switches, and therefore it has heretofore been proposed that the ringing equipment be placed at one lof such intermediate switches. In order to apply the ringing current automatically at the proper` time, a steering switch has been ,associated with such intermediate switch, which advanced one step for each switch usedpin the connecfY tion being built up,l and when connectionV was made with' the called line, radvanced to the ringing position. Thus, ringing currentv wasV invariably applied Vwhena predeter-` minednumber of switches had been set'. In` systems which include private `branch exV change lines, however, the numbery of switches used in establishing a connection when a private branch .exchange line vis called is 4different from thatused in'an ordi-v nary connection. The object vof the presentV invention is'to insurethe proper operation of the ringing equipment at the intermediate switch in` such system, irrespective ofthe number of switches used.

Toattain this'obj ect there is provided, ,in accordance with this invention, .a-.controlling circuit successively established or main-Y K tained in a given condition from the intermediate switch to and through the interven-A ino` switches to the final switch in the series by means of which the ringing equipment is rendered effective upon the completion" of the connection to the wanted line. v

In the embodiment shown herein the invention isapplied to a machine switching system,rand 'when the connection is extended to the switch succeeding -that at which the ringing equipment is located, the con- `trol magnet of the steering switch is ener-V gized, such switch being arranged to .ad-

vance upon the denergization of the Vcon- 'trol magnet( This magnet. is maintained Specicaton of LettersPatcn-t. Ptlllietl 0015; 26, p i

energized 'in a circuit .at each succeeding1 ing switch vto the ringingpcsition. vIf such line is busy,lmeans isautomatically` rendered operative to prevent'such ringing current from being' applied to thei'called line,

and a busy tone is instead automatically applied tothe calling line;

.Referring to the draw1ngsFigures 1 and f 2 taken'toge'ther illustrate diagrammatically one embodiment of the invention. 'In the embodiment shown, the line of the calling party A, upon initiating a call,may be connected to an operators position in any well` knownnianner` VVhenthe operatorrlcarns' the number ofv the wanted line, she asso'-V ciates herpsender113 by means of key K' with the leads 154and155 terminating in` aiirst selector not shown.' Thisselector is then set by the operatorl to pickout an idle incoming selector IS at the distantfofiice.

l The sender may be of the well-known finger wheel type which, upon restoring','inter-VV rupts the line circuit a number of times co'r .n

responding to` the l'number ofthe digit of the called line involved. Whenfthe call has been extended to the incoming selector IS- at thedistance office, the stepping relay 100V thereaty becomes energized over the followingv circuit: free pole of battery, contact 101 of. key If, conductor 155, arm 103 of the side switch of the` selector IS and its first con.y

ground. Relay 100 in attracting its arma-r` 110, and, .in attracting its left lV-armature, connects Vthe back contactof'relay 100 to the tact, stepping lrelay 100, arm 104, conduc- Ltor 154;, spring 107 and its lowercontact, contact 108 of the operators sender.v to

primary stepping magnet PM of the selecfV tor IS.

The operator now transmits the digit of.:` the wanted number with which the ,incom-f ing. selector IS is vconcernedby ymeans l,of

her sender 113, which interruptsfthe. circuit of relay 100 in the well-known manner.

Upon each retraction of the armature'. of

Y' relay 100, an impulse is transmitted to mag-v trunks 130, 131, 132terminating in connecnet PM, which steps the brushes 113', 114, tors having access to the desired line. The 115 ofthe selector IS in a Vprimary direc-k relayy 129 is slow-actingV and remains enertion into Operative relationto the desired gized during the transmission of the imgroup of trunks. Relay 112 is included in pulses. In attracting its armature, Vit enseries with magnet PM, and being slow-actergizes the escape magnet 133 of the selecing, is maintained energized, notwithstand tor S, which is constructed toV release the ingthe interruptions in its circuit, as the side switch upon its denergization in the armature of relay 100- vibrates. p This relay, well-known manner. c

in, attracting its armature, energizes the l/Vhen the sender 113 restores and mainvside-switch escapement magnet 116 of setains thecircuit of relay 100'closed, relay lector IS, which is constructed to release the 129, afteran interval, retracts its armature,

2. In position *2, arm 117 connects the secl ondary.; magnet SM of the selector IS in normal'contact SONC side switch upon its denergization in the thus denergizing magnet 133, which rewell-knownmanner. IVhen the sender v113 leases the side switch into position 2. In restores'and `maintains relay 100 energized, position'2 the interrupter 1341 is connected Vslow relay`112, after a slight interval, betothe secondary magnet SM over the side- Vcomes denerg'ized, and, in retracting its switch arm 135, and steps the brushes 136, armature, denergizes the` escape magnet 137, 138 over the selected trunk group. In 116 which passes the side switchvto position position 2 escapemagnet 133 is again energized vover'larm 139 and secondary off- Busy trunks are circuit with the interrupter V118, and arm those upon whose test multiples ground is 119 energizes the escape magnet 116 over present. Consequently, the escape magnet the off-normal contact SON, which is 133 is maintained energized as long as busy opened upon the first secondary step of the trunks are encountered. When the first unselector IS; Busy trunks are those upon grounded test multiple 132 is reached, magwhose test multiples 120 ground is present, net 133 is denergized and releases the side 5 asl will hereinafterV appear` the `escape magnet 116 is maintained Yenerside-switch arm 123 of the selectorY S, in its gized as long as busy trunks are encoun vsecond position,'maintains ground upon contered.4 When the lirst ungrounded test mulductor 125 leading to the escapeY magnet tiple 120 is reached, escape magnet 116 becomes denergized, passing the side switch intok position Arm 117, in lleaving position 2, opens the circuit of magnet SM,-

'v thus stopping the selector with the brushes 113, 114 and 115 upon the multiples 121,

` 122 vand 120 .of the selected trunk. Inposi- 116 'of selector IS. Thisy arm 123 Vengages itssecond contact before it leaves its first contact, and engages its'third contact before leaving-,its second contact. Thus,as this arm reaches position 3, theA escape mag- Consequently, switch into position 3. It will be noted that net 116 is held energized over the following circuit: free pole of battery, left windingV of tion 3, arm 119 grounds multiple 120, thus magnet 116, conductor 125, arm 124 and its causing the seized trunk to test busy to third Contact, brush 114,'multiple 122, arm other selectors and `energizes release relay 123 and its third contact,`brush 137, mul-V 'RRg which, inattracting its armature, intiple 131, side-switchV arm 200 of connector Arm terposes a break in the circuit of release C- and vits yfirst contact to ground. magnet RM of the selector S. In position," 139, in its third position, grounds theV mul- 1 of the selector S, side-switch arm 123 tiples 132 of the seized trunk to render the thereof closes the following circuit for the same busy, andalso operates a release relay escape magnet 116 of the selector IS: R2R2 of theconnector, which, in attracting ground, arm 123 and its first contact, multiple 12,2, brush '1141, arm 124: and its third contact, conductor 125, magnet 116, free pole of battery. The escape magnet 116 be-L comes energized when this circuit is closed, but does not release the side switch.V The operator4 now transmits the next digit'V of the wanted number. Upon each retraction ing circuit to primary magnet P2M2 of the 120 of the armature of relaylOO, an impulse is transmitted over the following circuit to the nal v121, arm 128, slow relay-129, magnet PVM, free V pole of battery. The selector S is jfthiisstepped in a primary directionlin operative relation to the desired group of tained energized during the transmission of 131')` connector: armature and back ContactY of the impulses, and, in attractingA its armature, Venergizes the escape magnet 203 of the connector side switch which is constructed to release the side switch upon its denergization in the well-known manner. The

connector brushes 204, 205, 206 are thusA driven in a primary direction into operative relation to the group of terminals containing those of the desired line 207, 208', 209. When the ,sender restores and maintains relay 100 energized, slow relay 203 after an interval, becomes denergized, and,

in retracting its armature, denergizes the' escape magnet 203 which passes the side switch into position 2, in which position arm 201 substitutes the secondary magnet SZMZ for the primary magnet AP2M2 yin the stepping circuit. Arm 200 in position 2 maintains ground upon conductor 140 con-k nected to the escape magnet 116, thus hold-V ing the same energized. p

The operator noviT transmits the units digit of the wanted number. retraction of the armature of relay 100 an impulse is transmitted over vthe circuit traced to the arm 201, from whence it passes over conductor 210 and the left windingV becomes denergized, andin retracting its armature denergizes magnet .203, whichpasses the side switch into position 3, in which the test ofthe selected line takes place. Arm 200, in moving olf its second contact, removes ground from conductor 140, connected to the escape magnet 116,0f the selector IS. The escape magnet thereupon de'e'nergizes and passes the sideswitch into positionr4. Whenthe sender-113m stores, after transmitting the unitsimpulses,

the operator throws the key K, so that the springs 101, 107 engage with their upperv and lower contacts, respectively, thusdis-v connecting the sender, from the leads 154, 155 and connecting the battery 157 thereto.

`Arm 104, in position 4, closes the. following circuit for relay 141; free pole of battery,

relay 141, upper left-hand winding of re- I peating coil RC, arm 104 and its fourth contact, conductor 154, spring'107 and its upper contact to ground. `Relay 141, in ate tractingits armature, energizes ringing relay 142 over the following circuittground, armature and front contact of relay l141, conductors 143, 144, armature and back contact of ringing cut-olf relay RCO,arma ture and back contact of relay 145, con-V ductor 146, relay 142,;free pole offbattery.

Upon each Relay V,142, in attracting its armatures, con-V nects the lfree pole of generator 147 tov the side-switch arm 200, and ground Yto the arml 201 preparatory to projecting theringing, f

current over the selected line. In' parallel with therelay 142, a relay 150 is energized, and in attracting its left armature, energizes relay 110. Relay f 110, in attracting its left armatura-opens the locking circuit of-re'lay 109 and'interpos'es a break in the circuit of release magnet RM. Y

11s stated, in position 3 of the connector side switch, the calledline is tested. If. the se`` lect'ed line is idle, full potentialis present upon the test multipleV 209 thereof, and the test relay 211 becomes energized over the following circuit: free pole of battery, cut-off.' .Y relay CO, multiple 209, brush206, both windings of relay 211 in series, arm 215 and its third contact to ground. VThe test krelay 211, in attracting its right armature, shunts out its right-hand high-resistance winding, thus so reducing the potential'upon ,the test multiples 2,09 of the selectedline that it will test busy to otherconnectors, In ,position 3arm 216 closes a circuit to energize relay 212.l Relay 212, in attracting -its'rightarmature, closes the vfollowing circuit `for Aconv nectork escapev magnet 203" which isl constructed to release the side switch from 'position 3 to'position 4, 'uponfits energization ground, right armature and front conta'ctrof relay 212, left armature and frontjcontact of relay 211, magnet 203 ,to free poleof bat-4 tery. lnvposition 4,'arms201 andf200 extend the ringingfcircuit to the called line, where- Y upcn the bell 216thereat is rung. 'The-ring ing circuit is as followsrfree pole/:of ringing generator 147, relay RGO, lower armature.`

and frontcontact of relay 142, arm 124and its fourth contact, brush 114, multiple 122,

.arm 123 and its third contact, conductor 140, brush 137, multiple 131, arm 200 .and-its fourth Contact brush 205, multiple 208,`con f denser 217 ,bell 216, multiple 207, brush204,

arm 201 and its fourth Contact, multiple 130, n

brush 136,1arm1281andfitsthird Contact,

multiple 121, brush 113,-: arm 127 and its'v' -fourth contact, upper armature and frontl contact ofrelay 142 to ground; When the V*subscriber at.substation B removes lhis ree" 'ceiver'from the hook, thefr'elay .RCOgbe-,r comes energized, and, in'attracting its arniafv ture, removes the shunt from about relay 145, which thereupon becomes energized in series with relay 142, and in attracting its armature shunts out relay 142 and locks itself up to ground at the armature and;V`V

front contact of relay 141. Relay 14,2, in i Y retracting its armatures, disconnects the ringing generator 147 'from thecalled line ,"andf'connectsl thereto the a repeating coilfrr.- RC. Upon the retraction of the armatures of 5 relay 142,v talking V'current is ,fedtothel I called lineover the following path :"vfree pole of battery, lower right-hand winding of repeating coil RC, called supervisory relay 151, lower armature and back Vcontact of relay 142, arm 124 vand its fourth contact,

Y brush' 114, multiple 122, arm 123 and its .third contact, conductor 140,'brush 137,

multiple 131, arm 200 and its fourth contact, brush V205, multiple 208, through the Y telephonie apparatus at substation B, multiple 207, brush. 204, arm 201 and its fourth contact, multiple 130, brush 136, arm 128 and its third Contact, multiple 12,1,brush 113, arm 127 and its fourth contact, upper armature and back Contact of relay 142, upper right-hand winding of repeating coil RC, to ground. Relay 151,-in attracting .its armature, closes the following circuit 'leading to the operators position: ground,

right armature andV front contactrof relay 150, ,armature and front YcontactY of relay 151, impedance coil v152, lower left winding of repeating coil RC, arm 103 and who thereupon operates the key K to break A the Vcircuit of relay VY141. Relay 141, in retracting itsarmature, denergizes relay 150,

which,in retracting itsr left armature, de-

energizes relay 110 which closes the release circuitV of theselector IS'as follows: release magnet RM, 'primary off-normal contact PON, right arinature and back Contact of relay 109, left armature and baclrcontact of relay 110 to ground. The release magnet,

inenergizing, withdraws the pawls from the Vshaft of'se'lecto'r I-S, and also restoresthe side switch in the welljlnown manner. The restoration of the selector IS denergizes relay RR ofthe selectory Sv, which, in retracting its armature, energizes the release magnet RM,of said selector over the oifnormal contact PONY; 'Magnet RM, in

energizing, locks itself inV a circuit including such off-normal contact, which' opens when.

the shaft of the selector reaches its normal I Y position, thus denergizing such magnet.

Similarly,the restoration offselector `S deenergizes relay R2R2 fof the connector C, which, kin'retracting its armature, energizes the release Vmagnet R2M2 of the connector over the off-.normal contact P2O2N2. This Vmagnet similarly locks itself over such off- Y normal contact and restores the connector V'side switch-. When thel connector brushf'239 interposes abreak in the circuit of reshaft reaches its normal position'and opens 'i f the off-normal contact P2021 2, release magnet R2M2 is de'energized. Ifythe lselected operator to transmit'vthe tens digit of the'Y line is busy, insufficient potential is present upon the test multiple 209 thereof to energize `,the test relay 211. Consequently, this relay remains inert, andy at its back contact connects the grounded pole of the battery to the ringing cut-off relay RGO over the rightarmature and front contact of relay 212, left armature andbackcontact of relay 211, resistance 213, Aarm 200V and its third contact, multiple 131, brush 137 ,f conductor 140, arm 123 and its thirdcontact, multiple 122, brush 114, arm 124 and its fourth contact, lower armature and front contact of relay v142, relay IGQ, ringing generator 147 to` ground. The marginalv relay RC() becomes energized when this circuit is closed, and in attracting its armature, removes the shunt from about relay-145, which thereupon energizes in series with relay 142. In attractingits armature relay 145 shunts out relay 142 and locks itself to groundl at the armature and. front'contact of relay 141 as described'. Relay V142, in retracting its armatures, conn'ects the repeating Vcoil RC to conductors 148 Vand 149, whereupon the following circuit is closed from the source of busy tone current 214 to notify the operator that the selected line isV busy: ground, secondary winding ofthe source of busy tone current 214, condenser 215, left armature and Afront contact ofIr-elay 212, arm 201 and its third Contact, multiple 130, brush 136, arm 123 and its third contact,;multiple 121, brush` 113,1arm127 and its fourth contact, upper armature of relay 142 and its back Contact, upper right winding of 'repeating coil 'BCto ground. The operator hears this tone by induction through the windings of repeating coil RC, and informs the calling party that the desired line' is busy, and releases the connection as described.

lAssuming now,v that the called line is located in a private branch exchange. In this casethe operation is the same as that described, yexcept that the selector IS, instead of selecting.. selector S, picks out another selector similar -to S, vwhich has access to the connectors 'C' in the private branch eX- change.r Assuming, therefore, that a selector similar to S has been set on the multiples 213, 219 and 220 of a connector in the private branch exchange, when the brush 137V thereof engages the multiple 219, the following circuit'is closed to maintain the escape magnet 116 ofv incoming selector IS renergized: ground, armf237 and the first contact Y of the side switch offconnector C, relay 239, multiplev 219, brush 137, arm 123 and its third contact,multiple 122, brush 114, arm

124 and its third contact, conductor 125,-

magnet 116, free pole of battery. The relay lease Vrelay VR3R3 of the connector.

The sender 113 is now actuated by the Y wanted line.

armature of relay 100 animpulse is transmitted over the following circuit to the primary stepping magnet PSMS of the' con nector C at such private branchy exchange:

armature and back contact of relay 100,

Aarmature and. front contact of relay 109,

conductor 126, arm 127 and its third contact, brush 113, multiple 121arm 128 and its third contact, brush 136, multiple 218, arm 221 of the connector vside switch, conductor 222, right winding of slow relay 223, magnet PSMS, free pole of battery.` Relay 223 remains' energized during the transmission of the impulses and closes a circuit to energize connector sideswitch magnet 230. The ma'gnetvPlif3 thus steps th'econnector brushes'224,`225 and 226. in oper-` ative relation to the group containing the desired line 227, 228 and 229. When the sender '113 restores and maintains relay 100 energized, the slouT relay 223, afteran interval, becomes denergized and opens the circuit of escape magnet 230, which releasesl battery. Relay 223, as before, remains ener-v gized during the transmission of the imulses and in attractin its*V armature energizes escape magnet 230. Y When they sender restores and maintains relayrlOO energized, slowrelay 223, after a slight interval, retracts its armature, denergizing magnet 230, which passes the sideswitchintoposi- Y tion 3. If the selected linel is idle,unshunted potential is present upon the'test multiples f229 thereof, and the following circuit is closed: yfree pole of battery, cut-offrelay 232, multipley 229, brush 226, ywindings of .test relay 233, armv 234' and its thirdy contact to ground. Relay 233, 'in attracting its right armature, shunts out its highresistance winding which so reduces the potential upon the multiples 229 of the selected'lin'e as to cause it to test busy to other connectors. In attracting its .left armatura-'this relay closes the following circuit to 'energize 'the' escapement magnet-230 :free pole-of battery,

magnet 230, left armature andffront contact of relay 233, rightarmature and front contact 'of relay 235, to'ground,Ak relay 235 being energized over arm` 236 and its third` g contact at this time. The "escapev magnet 230 is constructed to release the side switch into .position 4 upon itsenergization. As hereinbefore described, when the arni 237 Upon each Vretraction of the l Which corresponds to arm 200 y'of Vthe `c0,n nector C passed off its secondcontact, the escape magnet 116 of the selector :IS be. comes denergized and releases theV vside switch of said' selector into its fourth position,`in which relay 142 becomes energized,

as'described, to connect ringing generator 147 to the called line D toring the bell238 over the followin circuit; free pole of generator 147, yrelay CO, lower armature `and front contact of relay142, arm 124, brush 114, multiple 122, arm 123 and its thirdcon- -tact,-conductor'140brush 137,.multiple'219,`

relay 239, arm 237` and its fourth contact, 1

brush 225, multiple 228, bell 238, and condenser 240 at stationi), multiple 227, brush 224, arm 221 and ,its fourth contact, mul

tiplef218, brush136,l arm 128 and itsthird contact, multiple 121, brush113-, arm-,3127 andV its fourth contact', `-upper armatureand front contact' of relay 142 to'ground. i Y f Upon the removal of the receiverjatf substation D, ringing cut-oifjrelay'RCOis 'ener-V gized as described, from which point .the op'- f erations are the same asthosetraced. The function of relay'239 is to remove relay '.241

from the talkingcircuit.' Talkingcurrent is fedk to thev calledv station at the private branch exchange lover the 'windings' ofref-VA peating coil RG, the calledsupervisoryre'- the conclusion of the `conversation and *the gized, the former operating theusual supervisory` lamp beforev the operator andthe lat-f.

'95 lay-239 being included in this circuit. V'Upon replacement of the 'receiver by the called j i party, relays 151 and 239 becomedener-- l ter interposing a break in thej circuit of relay R31? to preventpremature release.' `The Voperator now, by means of they keyfK,-re

stores the'selectorsV IS and S. f'vWhenvthe:

241 is interrupted, whereupon thefollowing circuitis closed-for the release relay '-RSR? of the connector: free Apole of battery, ,relay i l RaRa, arm 240 and its `fourth contact, armature'and back contactfof :relayl 241,` left armature and back contact @of relay.1239, lground.'v RelayRRs, in attractin 'ritsVv arvmature, -energizesV release magnet; 3M8 ofv vthe connector .over therofffno'rnialcontact lBSN which thereupon energizesyand in attr-acting its armature, locks itself 'overfsuch1 i off-'normal contact; .When theixconnector brush shaft restores and opens.thiscontact,I` Y v 120.," If the.- selected linefha'd been busy, ithe I Y potential ypresent Tupon thev `multiple 229 thereofl would have .been insuicient tof energize'test relay 233, as described. f Thererelease magnet RSMS. :becomes denergiz'ed.

vlay 2,35, in thethir'd lor testing position, is]` however energized over arm 236, .andi'main-V ytrains relay 239 `energized over the following.

circuit to preventpremature release z ground,

right armature ofrelay; 235 yand, its front contact, .left armature 'olelay 233i 11d? its 105 v vselector S is restored, the circuit of Irelay' v leef Vir.125

.3o l Y- A relayR3R3-of the connector over the folrvlowing circuit: ground, lettarmature and front contact of relay 142, relay RGO, ring- Ving.generator14"/ to ground. Relay RC) operates as hereinbefore described, resulty ing in the deenergization of relay 142, which 10,

connects the right half of the repeating coil to the conductors 148,149. The attraction of the left inner armature of relay 235 connectsa source of busy tone current 243 in circuit with the repeating coil R il', to indicate to the operator that-the desired line is busy. This circuit is as follows: ground, secondaryk winding-244, condenser 245, inner left armature otrelay 235, arm'221 andits Vthird contact, multiple 218, brush 136, arm v.128 and its, third contact, multiple 121, brush 113, arm 127 Vand its kfourth contact, upper i ..armature andv back contact-"of `relay 142,

' `repeating coil RC to groundl. The oper` l,ator will then inform. the cal-ling party-of Vvthe busy condition of the desiredfline, and f lWillbreak downtlie connectionbyi actuat- *ing thel key K -and restoring the vselectors -lSvvand S. The Yrestorationof lthese selec- Y. torsfde-nergizes relay 239which, in retracting itslleftarmature, energizes,y the release i -backcontact of relay 239, armature and back A Y' contact. ot'relay 241,* outer lett armature of i f VRelay R3R3, in attracting its armature, op-

relay; 235, relay'RSRS, free pole ot'battery.

" crates. the release' magnet RQMSV as before described, and also restores the side switch.

From the foregoing it is evident that the circuitfarrangement of this invention is particula'rly advantageousA in machine switching Y'ltelephone Vexchange systems :employing priyate `branch exchangeY working, Since the side jswitch ofthe incoming selector will re-V `main in its third vposition .until the last setxofV impulses is sent,irrespective of the number of sets of suchimvpu'lses, whereasv in systemsr ofthe prior art, wherein the ring- Ving"equipment was located at'the incoming selector, the ringing control switch advanced onestep for each set of impulses and inva- V"riablyv applied ringing current at the end of y' jlapredeterinined numberlofsaid sets of impulses. A

v p .o Y m V1. Iny 'aF-telephone exchange` system, the combination with telephoney lines, vlink 'cir'-l Vc'uits terminating in automatic switches, a

:rotary auxiliary switch associated with'each circuit, means for deenergizingvsaid mag-kk the saine, meansztor interconnecting a net when the connector -is seton the called Y What' is claimed is:V Y

ofzsaid automatic switches lfor controlling ff ing and acalledyline over a number yof said flink circuits vand automatic switches in series, a vsource of signalingcurrent at an intermediate oneof said link circuits, aneleczation, a closed circuit including said deviceV`A Vand the link circuits in series automatically established and maintained, and meansior made with the called line device. Y 2. In a telephone exchange system, the

to operate said combination with telephone lines, switches yadapted to interconnect the'saine, a'rotary opening said ,circuit when connection is Y auxiliary switch associated with each otsaid i switches to control the same, a source of signaling current at an intermediate lone ont said switches, and an electromagnetic responsive .device for operatingitsV associated auxiliary switch to connect said source to said intermediate s'witcliupon its -deernergiclosed circuit extended to Aeach succeeding saV ization, means for including said device ina switch in series, and means for openingV said n circuit when connection is made' with the called line to operate said device to connect saidV source thereto. Y Y Y c 3.1n a telephone exchange system, the

combination with telephone lines, link cir- Y cuits, means for interconnecting A,a calling and a called lineovera number of said link;

circuits in series, a source ot signaling cur- Vrent at an intermediate one ofsaid link circuits, asteering switch at each or" saidlink circuits to control the same,a magnetv associated with the steering switch' of. the in-f termediate link circuit adapted'to advance the same to connect said source to vsaid link circuitk upon vits denergization, means `for energizing said magnet, means for main- 'taining saidv magnet energizedfincludiiig a circuit at yeachsucceeding link circuit, and means for deenergizing said magnet when Y the connector is set on. the called'line.

4. In kav telephone yexchangesystem, the

combination with. teleplione'lines,` link cir` cuits terminating Vin selective switches, means for interconnecting a` calling and a called line overy a number ofsaid link circuits in series,` a source of signaling current atan intermediate one of said linkfcircuits,` a multi-position steering switch lat eachk of' said link circuits vto controlthe same', a magiooV Y net associated with the steeringswit'chY ot Vsaid intermediate link circuit adapted Vto advance the same to connect said source to 1 saidulinkcircuit upon'its deenergization, v vvmeans for energizing said magnet;- means for maintaining saidl magnet energized in- `cluding a'circuitpa't each succeeding link g .125`

line, and meansV for preventing said signalfisioV l.

1,356,639 Y l l2 5. In a telephone exchange system, the lcluding theauxiliary switch at said inter combination with telephone lines, automatic mediate link circuit adapted to connect said switches including selectors and a connector, source to the conductors Vof said link cir-v stepping magnets therefor, a sender adapted cuit, a magnet for operating said switch 55 to operate said magnets to set such switches when denergized, a closedcircuit' therefor to interconnect said lines, a source l'of sigincluding said link circuits in series, and naling current at lan intermediate selector7 means for automatically maintaining said aside switch for each of said selectors to circuit closed until connection is made with control the same, means for advancing the the called line, and means automatically op- 60 1o steering switch of said intermediatey selecerated if the line is busy for preventing the tors when said selector is set to place said operation of said magnet from becomingV sender in operative relation to the magnets ecctive to applycurrent to the called'line. of the succeeding switches, means for main- 8.' In a telephone exchange system, the.. taining said steering switch in said posicombination vwith telephone lines, link cir- '65 tion while said succeeding switches are becuits terminating in automatic switches, ing set7 and means for advancing said steer-` means for interconnecting a calling and a ing switch to connect ysaid source of signalcalled line over a number of said linkl ciring current' to the selected line when the cuits land automatic switches inseries, a connector is set thereon. y Y rotaryv auxiliary' switch associated with each 7.0 V 6. In a telephone exchange system, thev ofsaid automatic switches for controlling y combination with telephone lines, automatic 'the same, a source of signaling lcurrent at switches including selectors and a connecan intermediate oneof said ylink circuits, a tor.; st ping`magnets therefor, a'V sender device including' the auxiliary switch at ,/L/daptied to operate saidnagncts to set such said intermediate link circuit ladapted to 175 c connect said source to said linkcircuitnpon switches to interconnect lines a source p l y ts denerglzation, avclosed circuit Vinclud-fLN of signaling currentfat one of s lecto a side switch-for said selector includi'n escapement magnet adapted to ad side switch upon its denergizati' for' dener'gizing said magnet whe' lector'is seg-t to advance saidA sil place saids'ender in operative relv 'f magnets of the succeeding switch for again energizing said escape? 35 cluding a circuit at the succeed and for maintaining the same enterb cluding a circuit at each succeedinv si i-tcl closed before the corresponding the preceding switch is opened '40 for denergizingsaid escape magnet .to ac 4 vance said side switch to connectlfsaid source of signaling current to thev selected lin when the connector is set thereon.` v 7. In a telephoneexchangegsystem, th combination with teephone lineslink .cir cuits including switches, a rotary auxiliar' switch at each of said`- switches'gjfineansifor interconnecting a calling and '-gfcalled lin over a number of sai'd link'circuitsinserie ng said device and the link circuits iny series i automatically established/and maintained, p "i -means automatically actuatedwhen" connection' is made with the called line for endering said circuit effective to operate aiddevice. l f

9. In a telephone exchange system,tele )hone lines, link circuits terminating in iutomatic switches, each of saidL automatic 'witches being provided with a step by step uXiliaryv switch for controlling the same, means including said link circuits and auto!r natio switches in series for interconnecting calling and a called line, a source of ringng current at an intermediate switch of the series, and means located at said interme- :diate switch andv controlled successively over said flink circuits for connectingsaidt .source of ringing current to the series of ink circuitswhen'the called line is.. found. f Inrwitness whereof, I hereunto subscribe Q y name this 13th day of November,` A. D. 916'.V Y 1

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