US1541386A - Machine-switching telephone-exchange system - Google Patents

Description

June 9, 1925. 1,541,386

l.. PoLlNKowsKY ET AL MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM G era/d Dea/nn y AW June 9, 1925. f 1,541,386

L. POLINKOWSKY ET Al.

MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM zmnoh F'lledleb. G, 1919. v 5 Slxfgets-sheetv 2 I Gera /d Dea/nn June 9, 1925.

1,541,386 L. PoL|`NKowsKY ET A1.

Filed Feb. e, 1919l L// /Do//n /m ws/ry G'era/d Dea/nnA ,mile 9,' 1925. 1,541,386I

L. POLlNKOWSKY ET AL.

MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM 5 Sheets-Sheet 4 Gei/fd/d Peak/n @MM Am? June 9, 1925;

44.9'l lpllame l L. POLINKOWSKY ET AL MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM Filed Feb. e, 191s lIHII s sheets-sheet sv ISBW . man: i

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:19t lonzfnn.

@atterrit-:d June 9, i925.

Unire srArl-:s

YPATENT OFFICE.

LIPA POLNKOSKY, OF NE'W YORK, N. Y., AND GERALD DEAKIN, OF LONDON, ENG- LAND, ASSC-NOES TG TvVESiEIiII5T. ELECTRC COlVIPANY, JINCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

MACHINE-SWITCHNG TELPHONE-EXCHANGE SYSTEM.

Application filed February 6, 1919.

To all whom t may concern.'

Be it known that we, LrrA Poninirowsiir, a citizen of Russia, of 463 West Street, New York, New York, and GERALD DEAKIN, a citizen of the United States of America, of 34 Norfolk Street, Strand, London, W. C., England, have invented certain new and useful improvements in Machine-Switching Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

rlhis invention relates to machine switching telephone exchange systems, and more particularly to machine switching telephone systems of the full automatic type.

A feature of the invention is the provision, on a register set, of a calling signal which, when a register is engaged with a line but does not receive within a predeter` min-ed length of time-setting up impulses from the calling substation, appears before an operator to notify her that her connection over the register is required with the calling line.

A further feature relates to an arrangement wherein the registers of the register controlling mechanism take a special setting in response to certain designa-tions sent over the calling line for controlling the eX- tension of such line to an operators position.

in the drawings:

in F ig. 1 is shown a subscriber line and a first line finder;

Fig. 2 shows a oord circuit comprising a secondline finder and a first group selector;

Figs. 3 and 4 show a register set;

Fig. 5 shows a final selector;

In F ig. 6 is shown a common arrangement for the timely delay of a monitoring signal; and

Fig. T shows diagrammatically the subdivision of cords in pairs.

The system disclosed as embodied in the present invention will bev best understood from a description of the operation thereof.

A subscriber, when desirous of obtaining a connection, removes the receiver from the hook, operating thereby the line relay 201 in the exchange. circuit is then established over the individual resistances 202 and 203 of the subscriber line, the front contact of line relay 201 and both windings of the common starting relays 204, and a po- Vof this terminal'is able to operate.

Serial No. 275,483.r

211 of the free line'finders in the group, the

individual circuit of a power magnet 211 being closed over the back contact Vof the corresponding vtest relay 212 and disconnecting relay 213. The power magnet 211, when energized, causes in the well-known manner the rotation of the brush carriage of the line finder alongthe terminals of the subscriber lines. The right-hand high-resistance winding of test'relay 214 of the line finder, theV brushes of which happen to stay on the terminals of the calling line, or are Vthe first to reach these terminals, is energized ina' circuit over terminal 210. The left-hand lowresistance winding of` relay 214 is brought over its front contact in parallel to its highresistance winding, reducing the potential at terminal 210 so' that no test relay of'another line finder' which passes the multiples When the brushes are centered and contact 219 of the brush carriage is opened, the second test relay 212 is connected in series with the lefthand winding of relay 214, and also becomes energized. The ower. magnet 211 is disconnected on the lback contact of this relay, and a circuit is closed over its front contact including the holding magnet 215 of the line l back contact of relay 205 and front contacts of relays 204.

.Each second line finder, together with a first group selector, represents a cord which is provided with an individual sequence switch 220 for establishing the dierent circuits in succession, and a searching sequence switch 280 for obtaining a connection with a free register set. duc-ing thenuinber off simultaneous rotating, secondi f-ree line finders, Vthe cords are divided in pairs, as shown in Fig. 7 and are arranged so that when both cords are free,

one sequence switch-220 is in its positionV 1,.

and the correspondingsequence switch of the second cord is in its-position 1S. Only the second line finder on which the sequence "s'Vifitfclies'220er" the cerd is in position l is line`V 221er" the line brush carriage, over` ba eo'n'tactof release relay'231`, front contact/f offrelay 222, l back contaetpof relay 232 and SQ(711161109.Y vvswitch 226V bottom. The

brushes' ofthe secon'd'line'iinder rotate, and

reaching terminal 230,l vtest relay V234 is energized in acircuitoyer contact 282 bottomofisegnence switch 280, contact 227 bottoml of'sequence switch `220, right-hand back elitaet. ef metriielleds relay 224, rightlialnd high-resistance winding ofrelay 234,: sequence 'switch contact 228 bottom, terminalf230, resistance 211?, 'front contact oir relayL 2l'2kand back contaetqof` relay 213.

The left-hand low-resistance winding of re-A lay 234 is brought inV parallel ,to its highsresistancefwindifngover its vfront Contact and contact 239 Vof the li;ne.finfl,1 brush carriage. Terii'iinal230 .is made busy fory otherY line finders lWliengcontzlict 239 is opened the winding Vof the, secondptestI relay 232 is4 brought;'iny the saine circuit, and relay 232 becomes energized, disconnecting on its black contact the .po-wer magnet 221, whereas sequeneeiswitch 220 energized in a circuit over its .contact 229 top, front contacts oit' relays 232 Iand222,and back contact of relay 231. i in parallel to thesequenceswitch 220 thfholding magnet ofthe line finder is connected oyer lits contact 233 bottom. The brusli carriage is arrested on terminal 230,- while sequence switch 220 starts from position Land moves under the control of its local .contact235 into position 4.

When sequence switch 220 passes positionl 2, the high resistance winding of/relay 234 1s disconnected at sequence switch contact 2277bottlom,A and the energization of relay 234l is Imaintained' over its low4 resistance i winding.y Thenscquenceswitch 220 reaches positioni3 alecircuitis closed 'for the energizat'io'n of' the cutoff' relay 207 of the subscriber line, relay 213 of the first line finder For the purpose of re-V and connecting relay 235 ofthe cord, the circuit including terminals 218 and 238, lefthand back contact of relayy 224 and sequence switch contact236 top. Relay 207 causes the disconnection of theline relay 201, and this in turn the disconnection of the common starting relays 204, so that the circuit for the power magnet of the still rotating free first line finders is opened and the brush carriages of these line finders are arrested. At the same time the test relays 214 and' 212 on the first line finder in use are deenergized and cause the deenergizaticn of; the holdingv magnet 215, the common relays L16 and the relays on the second line finders corresponding to relay 222. rPhe power magnets of the remaining second line finders are then disconnected and the brush carriagesof these line iinders are arrested. Relay 23,1 andretardatio'n coil 237' are now connected over sequence switch contacts 242 top, and 243 top, and both front contacts of relay 2,35 with the calling subscriber line, whereby relay 231 is energized.

In position 4 of sequence switch 220 the test relays 234 and 232 are disconnected from terminal 230 at sequence switch contact 228 bottom. The magnet of sequence switch 280 is now energized in a circuit over contact 244 top of sequence switch 220, back Contact of relay 232, contact 227 'top of sequence switch 220 and contact 282 bottom. Searching sequence switch 280`st`arts from position 282 top of sequence switch 280, right-handv winding of rel( y 234, contact 246 bottom of sequence switch'220, contact 283 of sequence switch 280, wire 293, contact 368 top of sequenceswitch 350, contact 322top of sequence switch 320 and left-hand winding of relay'323. Relay 234 produces over its front contact the connection of its left-hand winding together with winding of relay 232 in parallel to its right-hand ,winding before Contact 282 is opened, whereby relay 232 at the cord and relay 323 at the register set are energized. Sequence switch 280is disconnected at back contact of relay 232, but continues its movement until its contact 281'is opened. At the front contact of relay 232 a circuit is prepared for the energization ot sequence switch 220, but this circuit is only closed 'shortly before sequence switch 280 is arrestedA and its contact 282 bottom is closed.l A' delayY in the ener'gizationv'of sequence switch 220 is gained and so makes certain imi lit)

that relay 234 is able to maintain its energizatioii over its left-hand winding after contact 282 top has been opened.

Should it happen that the searching sequence switches of two cords simultaneously reach the saine test wire 293 oit the register set and the corresponding test relays 234 on both cords become energizeda they are not able to maintain ,their energization over their low resistance windings brought in parallel to one another. rTime ieV therefore gained for relay 234 to deenergize, and relay 232 isdeenergized before sequence switch 220 can start from position 4. The searching sequence switch ot' the cord on which the test relays could not maintain their energization continues to rotate and to search for another lree register.

Sequence switch 220 when energized starts from position 4 and moves into position 5, in which the subscriber line is disconnected at sequence switch contacts 242 top and 243 top from the release relay 231, and is connected over the saine sequence switch contacts, the contacts 284 and 285 respectively vof sequence switch 230, wires 294 and 295, and the contacts of rest of the monitoring key 301 individual to the register set on the complaint desk with the secondary windings ot the dialing tone coil 324 and the steppingin relay 325.

The energization ot relay 323 on the register set provides a circuit tor the energization ot sequence switch 320 over front contact and holding winding of relay 323. Sequence switch 320 which controls the changeover in the circuit o the register set for the setting up ,of the registers from the subscribers dial, starts from position 1 and moves under the control of local contact 321 into position 3. After sequence switch 320 leaves position 2, the lett-hand winding of relay'J 323 is disconnected at sequence switch contact 322 top, the right-hand holding winding is thereby short-circuited at contact 321, and relay 323 is deenergized. Relay 325 is energized in the circuit over the calling subscribers line before sequence switch 320 reaches position 3. Relay 326 is now energized in a circuit over back contact of relay 323, and sequence switch contact 327 top, and a circuit is established for the energization oi"- the thousands register 100 over contact 328 top ott sequence switch 320, back contact and right-hand winding of the impulse limiting relay 329, sequence switch contact 330 top and front contacts of relays 326 and 325. The second winding of the diiierentially wound relay 329 receives current over the retardation coil 331. Relay 329 remains deenergized, whereas register 100 starts from position 0 and moves under the control ot its local contact 101 into position 1. 1n position 3 of sequence switch 320 the primary winding of the dialing tone coil 324 is connected over Vsequence switch contact 332 to an interruptor 333, and when the calling subscriber hears the sharp dialing tone,he winds up the dial on his station according to the first figure or" the'wanted number. fis soon as the dial is given tree it returns to its position oi rest, producing interruptions in the line circuit, the last interruption being of longer duration than those preceding.

Assoon as contact 101 on register 100 is closed, a short circuit around the right-hand winding' of relay 329 is produced, and relay 329 becomes energized, disconnecting on its back contact the circuit for register' 100 which maintains its energization over its contact 101 until the register reaches position 1 and contact 101 is opened. Relay 329 remains energized until the line circuitis opened at the dial and relay 325 is `deenergized. Relay 329 in closing its back contact again prepares the circuit for the register 100. As soon as relay 325 is again energized, the register 100 receives current in the circuit described, and starts from position 1, causing the energization of relay 329 as soon as contact 101 ot register 100 is closed.

@ver the back contact o relay 329 relay 337 is also connected in parallel to register 100, which relay 337, when energized, maintains over its ront contact the closure ot' the circuit for relay 329 independent from the contact of relay 325. The speed with which the register is moving is so selected that a register starts and completes its step in a shorter time than the total time of an opening and a closure on a fast dial. Through variations in the speed of the dials, the resistance of the line etc., the stepping relay which follows the impulses in the line may not stay on its iront contact a sufficient time to ensure the starting of the register, whereas the quick energizing relay 337 makes it certain that the circuit once closed on the front contact lot relay 325 is maintained until the register starts and inoves trom one position into the next. Relay 337 has also a further purpose in that relay 329, once energized, keeps its back Contact opened until relay 337 is deenergized. 1f relay 337 is not provided and relay 325 opens its front contact before the register has reached its next position and has opened its Contact 101, relay 329 would also become deenergized and both its windings in series would be brought over its back contact in parallel to the winding of register 100. Relay 329 would make an attempt to again leave its back Contact which may then happen to be opened at the moment the front contact of relay 325 is again closed. Relay 329 would then become immediately energized over its lefthand winding, and the impulse will not go tothe register, which will then tall short.

(inthe other hand, it relay isrd'eenergized and its back 'contact is closed at the moment' contact 101 ot' the register is opened, windings lof relays would be brought in parallel to thewi'nding of register 100, delaying the deenergization or' the register, and'tliis would cause an oyerstepping ol the register. Relay 33'?, which is'maintained operated as long as contact lOl is closed, holds over its front contact the once energized lett-hand winding oft relay under current, and hinders th-is relay from closing its back contact eve-n it the stepping relay has left itsA front contact. rl`his enables a sae operation of the register whichcan now be driven with a higher speed, and therefore makes it certain that the register wouldcomplete its 4step quicker than any dial which may lose its adjustment and increase its speed. l y

yWhen on the last interruption at the dial ofthe line circuit, relay 325 remains deenergized for a comparatively longer time, it closesat its haelt contact a circuit tor the energization 4otfya slow-operating relay 334e toruahtime'suilicientrto energize vthis relay. The left-hand winding of relay 323 is then clos'ed in a circuit over `front contact of relay l331i, and sequence switch 320'is again energized in .the circuit over `front contact olf relay 323. Sequenceswitch 320 starts from position 3 andrmoves into position G. The relation between theL openings o the line circuit at the dial, the time relay 324 uses for its operation, and the time sequence switch 32D takes to move into the following positionLis such that at all variations in speed and adjustment oft the dials 4or voltage the exchange, relay 334 does not perate during the short interruptions `in the line circuit, but is energized and causes the start of the sequence switch on a long interruption at the dial, whereas the time this relay needs to energize, together with, the time the sequence switch 320 takes to move into thel Jfollowing position is under all circumstances longer than the time relay 325 remains deenergized during the long interriiption at a dial. ln fact relay 325 is already energized over the subscriber line be- :toresequence switchy 320 reaches position 5.

V'Vhen relay 323 is energized, it opens on its hackgcontact the circuit for relay 326, which immediatelyv opens the circuit for the energization of the registers, so that when relay 325 becomes again energized, the register circuit is maintained opened at front contact of relay 3,26 unt-il sequence switch 3,2() reaches position G. Vhen relay 325 opensIV its back contact, relay 33e isdeen` ergzed, andV opens the circuit ofthe lefthand winding of relay 323. The right-hand winding of this relay being short-circuited at contact 321, relay 323 is 4c leenergized before sequence switch 320 reaches position 6.

ige/insee llfhen sequence switch 320 moves over position an addunmal energization ot' register l0() is caused ina circuit over Contact 3.30 bottom, and register makes an additional Sten in the directory of subscriber numbers be-l ginning with the ligure l so asv tov avoid numbers beginning with the figure O. o

V27 hen sequence switch' 320 lleaves position the register 100 is disconnected at contact 323 top, and the hundreds register l'lOis connected over sequence switch contaet v32.8 bottom, whereby this contact is closed earlier than contact 32?', vso that the circuit 'for the register 110 is ready before relay 326 en'- ergized. rl`he lirst energization ot register ll() takes place immediately the front contact of rela-y 326 is closed in af circuit indarling contact of register 100.I Regista' il() starts from position 0andin clos-ing its contact lll, the right-handv winding of relay 329 is short-circuited and =relay 329l opensits back contact, whereas the register completes its step under the control orf. its Contact lll and is arrested in position l'. -Relay 33'? is now connected in parallel to register 110, and maintains the energization of relay 329 during the time conta-ct lll is closed. l/Vhen the dial is released a ysecond time, register is brought to acorrespond ing position, whereas sequence switch 32() is' zulvanced trom position G into position l0, in which the tens register 130 is now connected in the stepping circuit over sequence switch contact 335 top, and is setI up accordiiig' to the third series of impulses from the dial. Sequence switch 320 is then advanced from position l() intoA position`l3, in which the units register le() is connected in the step ping 4circuit over sequence switch contact 33o bottom. The-n the dialing has been completed, sequence switch 320 is advanced from position i3 into position 16, in which the se quence switch remains' waiting until thel selectors have been set up under the control ot the registers,

The capacity of the exchange is assumed to be two thousand. First group selectors and tinal selectors are therefore provided. rllhe register 100 controls only the odd and even thousands, whereas the hundreds register l1() controls the selection the corresponding level at the first group selector. The position ot the registers determines the translation 'from the decimal number system of the wanted subscriber to the system of the switches, whereby register 100 determines the translation `for the first group selector. Five levels on the lirst group selector are reserved tor the odd thousand numbers and the other live levels for theeven thousand. The setting up of the lirst group selector takes place during the time the subscribercontinues the dialing, and since the trip spindle of the first group 'E he purpose of it is toenable the, use

selector has to take a position according to the position oi the registers 100 and 110, the operation of the trip spindle of the first group selector is delayed until the first two impulse series are completed on the dial. rlhis corresponds to sequence switch 320 leaving position 6. In position 7 ofsequence switch 320 a circuit is closed for the energization of sequence switch 350 over its contact 352 top, contact 103 of register 110 and Contact 338 top ot sequence switch 320. Sequence switch 350 which controls the connection of the registers in succession forthe control of the fundamental circuit of the selectors, starts from position 1, and under the control ot its locall contact 351, moves into position 3. In position 2 of sequence switch 350 is the right-hand winding of relay 359, energized in a circuit over back contact of stepping-out relay 355 Vand sequence switch contact 354 top. Relay 359 keeps open at its back contact the circuit for resetting of the registers.

Assuming that the number of the wanted i line is 1253, when the dial is wound up and then released, eight short and one long opening are made in the line circuit. The register having made its first step vbefore the first interruption of the line, and not receiving any current after the long interruption, has therefore made nine steps under the control of the dial and one step'under the control of contact 330 bottom. The register 100 is therefore again in its position 0. Register 110 has been energized eight times, under the control of the dial, and is therefore in position 8. When sequence switch 350 reaches position the fundamental circuit is closed over contact 356 bottoni of sequence switch 350, back contact of relay 357, winding of stepping out relay 355comnien conductor 296, contact 286, bottom o't sequence switch 280, contact 247 bottom of sequence switch 220 and. winding of relay 222. Both relays 222 and 355 are energized.

. Relay 355 disconnects on its back contact the circuit for differential relay 359 which Ais now deenergized. Relay 222 causes the energization of sequence switch 220 in a circuit over back Contact of relay 231, front contact of relay 222 and sequence switch contact 229 bottom. .Sequence switch 220 starts from position 5 and moves into position 6 in which the trip spindle. magnet 248 is energized in a circuit over sequence switch contact 249 top and front contact of relay 222. The trip spindle rotates and produces at its contact 250 top over sequence switch contact 223 bottom short-circuitings around the winding of relay 355. As soon as the back contact ot' relay 355 is closed, the register 110 is energized in a circuit over contact 112 of register 110, Contact 361 bottoni of sequence switch 350, back contact and left-hand winding' of eiay 359, back contact of relay 355 and sequence switch contact'354. Simultaneously with the energization of register 110,

lrelay 362 is also energized and provides lover its front contact a bridge to the contact of relay 355. Relay 362 in the" circuit for the outgoing impulses has the same purpose as relay 337 in the circuit of the incoming impulses, and enables a sate operation of the registers. As soon as contact 111 is closed, the left-hand winding ot relay-359 gized. On the following closure of contact 250, relay/355 is again deenergized, and register 110 energized, starts from position 9 and moves into position A0'. On the `fol lowing closure of contact250, relay 357 is energized in a ,circuit over sequence l'switch "Y contact 363 bottom, contact 104 of register 100, contact 114 of register 110, contact'361 bottomof sequence switch 350, bacl' contact and left-hand winding of relay 349 and back contact of relay`355. Relay 357 opens the fundamental circuit. In parallel to the right-hand winding of relay 357 is also connected the sequence switch. 350, which is energized, starts from position `3 and moves into position 4.

IVhen contact 351 is closed and the lefthand winding of relay 359 is short-circuited, this relay is energized and maintains its energization over back Contact ot relay 355. After contact 250 of the trip spindle in also opened, relay 222 is' deenergized, and sequence switch 220 is energized in a circuit over its contact 251 bottom and back contact ot' relay 222. Sequence switch 220 starts from position 6 and movesvinto position 7, in which the test relay 234 is connected at sequence switch contact 228 top with the test brush 252 of the first group selector. Relay 222 is now energized in a circuit over resistance'253, contact 246 top of sequence switch 220, contact 283 bottom ot sequence switch 280, wire 293, back contact of relay 339 and contacts 240 top of sequence switch 320. The power magnet 241 of the group 4selector brush carriage is thereby energized in a circuit over contact 254 bottom of sequence switch 220, back contact of relay 232 and front contact of relay 222. The brush carriage rotates in the well-known manner with the brushes along they terminal row determined by the position of the trip spindle. In reaching the test terminal of a free final selecto-r, relay 234y is energized in' a circuit from ground, over contact 282 bottornof sequence switchv 289,# contact 227 bottom of s egnence switch ,320, rightfhand bach contapt-'otrelay right hand winding of .iiilsew-th 45.0 individual t@ the final se c torV and resistance y442. In parallelto l i' 442 is'also. connected a high-resist- 1 e release vrelay 443. Relay 234 brings its lowl-fesstne'wding inparalll t0 its viis'tarice'. :wi11ding,fand makes the. terii isinals #helical ,Selecta fbusy- '45 SOO-.I1 as @Getest 2.69 of 'the brush Camas@ 1S ,pened,and shunt around relay "i l, this" relay Yis also encrgized,n the disconnected at the N ontact of relay/232, 4while a circuit is .rreridedfef (the s feszstoii Ot' seque-ese t'ch.22 0 o xger contact229 top ,and front 'i t of inlay 232.v i In parallel to Athe ,Q uence switch also connected, over `its @au et. -lf4 tei?, the .holding meile? 245 lof rele eeibfush me@ is a ested and sequence switch 220y starts from ion ',7 and moyes .over position 8 into fpps Q', in which the' fundamental circnit @persil-Let .Se use@ Switch 'Contests 247 ,tensed .25.5 fb@ .11.1 t@ the final selector, readies-the @las ..116 Qf the fundamental @1rattbereeister set-i eqiien'ce switch. 35,0 remains in position the tensiaiid units registers have been 'set np unf erfthenontrol of the'dial, and se* 35. in which position sequenceswitcli 350 .mp and contact 341 v bottom of sequence Y 320i Sequence switchf350 starts from tiene@ 4 Mild moves-iat@ Position 'in which the fundamental circuit closed at 4 0 e .register .set over Vback Contact otV re- 357, and sequence switch contact .356 top and concliictor '297, and at the Viinal sele or oyer the contacts 444 bottoni )and `445 to p bf seq uciice'switch 450. Relay 452 at fthelilnalfselector and relay -355Qat thc-'register Iisetware energized; .relay 359 is deenercircuitis closed .for'the energizaof sequence s witcli450 over its contact `6 -bettbmind wat www@ Qf relay 4.52- uencenswitch 450 startsfrom position `1 J .1noyes'- under the control of' its 1local contact 1451'into position 2, inl which the trip spindlemagnet ,448i is energized in acircuit seqiicncefswitch contact '447 bottom and y @nieuwe eine@ The trip Spinle @tessile rrvds its? Gentech 455 QYIf- Sqil'nce contact 449 bottorn 'short'-circnitingfs around `relay v355 in .theta rn-llillfiruit i `lifter-1:relay 'is' deeergizsd, resister 'i I Ugizcd a circuit oyer its con- .25 eoltet :3.67 f .Sequence Switch nd back contact-of: re ay .3159. lRegister s ition 5 andmoyes into ff1234, coiitfact top of sequenceVV tch 22O, tesft brush .252, contact 441 ot is 'energized in a 'circuit over Contact 363j position O under the control ot relay 355,21 circuitY k established on the following deenergization of a relay 355 over contact 134 of register 130, andY contactl 352 top O seqnence switch 350 for the energization or the sequencefswitch and the relay 357. The

fundamental circuit is ther'ebyf opened, whereas sequence switch 350 starts from posiing o f the Vfun damental circuit at b aclr'ccir tact of relay 357 is so adjusted that contact 447 of sequence switch 450 Vis opened, 4before relay 452 canbeenergized a second time over the iijundamental circuit, whereas the energization of this relay taires place before sequence switch 450 reaches position 5. The power magnet 4 61 of the brush carriageis 'now energized in a circnitover sefjqnence switch contact 456 top'andfront c onytac:h` t f'1'elay 452. The brush carriage lrotates alongthe sixth terminal row; a series l of.shortcircnitings of the steppingrelay Y 355 1n the fundamental circuit is again prod iiccd Yatcontact 457 top of the brush car riage oyer sequence switchcontact 449.

When the relay 355 is deenergized, a circuit is established for the energization of register oyer contacts of relay'355 and 35,9, contacts 367 bottom of sequence switch 350 and contact 142 of units register v140. After register v140 reaches position O, under the control of relay 355,a circuit is tablished for the energization of sequence switch 350 and relay 357 at the foi'lowing ceenergizaticn of relay v355, oyercontact143`of register 140, back contact of relay 374, con.

tact-144er register 14() and contact 352'top .of sequence switch 350. Yrlhe `Jfundamental circuit is again opened and sequence switch 350 startsfrom position 7 and moves into position 18. When sequence switch 350 leayesposition 9, the circuit in which relay 222 has been niaintained energized during the progress of the Vselection is now opened at contact 368topof sequence switch 350, causing the deenergization of relay 222 in 4the cord, whereby sequence switch 220 is energized inthe circuit oyer its contact 251 bottom and back contact of relay 222. Se-

quence switch 22() starts from position 9.

In position of the sequence `switch the fundamental circuit of the VregisterV `set is disconnected at contacts 255 and 247 of seq uenceswitchY 220. Supervisory relay 232 and retardation coil 257 are connected over iitelegiei 13,5 'is resterait@ ,Saque-r1.0@ Saiten. contact,- 255 Lopend 25W-'QP- ico to the final selector. When sequence switch 220 leaves position 9, stepping relay 325 is disconnected troni the subscriber line at sequence switch contacts 242 and 243, and the subscriber' line is again connected over these sequence switch contacts with relay 231 and retardation coil 237. ln position 10 .sequence switch 220 is energized in a circuit oye-r its contact 258 bottom, and back contact ot' relay 262.l Sequence switch. 220 moves therefore over position 10 into pesition 11.

As soon as relay 325 at the register set is deenergized, sequence switch 320 is energized in a circuit over its contact 348 bottom. Sequence-switch 320 starts from position 16 and moves into position 1'?. When sequence switch 350 reaches position 18, a circuit is established for its energization over contact 37 2 bottom ot sequence switch 350, back contact of relay 326 and contact 352 bottom of sequence switch 350. The sequence switch starts from position 18, and moves into position 1, in which the lett-hand winding of relay323 is energized in a circuit over contact 354 bottom of sequence switch 350 and contact 322 bottom or' sequence switch 320. Sequence switch 320 is now energized over lfront contact 03": relay 31.3, starts from position 17 and moves into position 1. rln'he register set is 'free and can be taken for a new call.

After the :fundamental circuit has been opened at the register set, the relay 452 is deenergized as -soon as contact 457 top is opened, the power magnet 461 of the final selector is disconnected, whereas sequence switch 450 is energized in a circuit over contact 453 top and back contact ot relay 452. In parallel to the sequence switch, the holding magnet is. connected over its contact 458 bottom. r1`he brush carriage is arrested, and sequence switch 450 starts from position 5 and moves into position 6. On subscriber line g-roups on which the inal selector is arranged to search for a free line to private branch exchanges, the cuto relays 488 on the single subscriber line and on a last line to a private exchange are provided l with shunts 489. The final selector is provided with a special test relay 463 which can energize over the cutot relay of afree private branch exchange line. Relay 463 is also energized over the test terminal of a single subscriber line, or of the last private branch exchange line, disregarding Whether the line is free or busy; assuming the line free, test relay 463 is energized in a circuit over sequence switch contact 459 bottom, test terminal ot' the subscriber line 470 and cutoii relay 488, respective resistance 489. A circuit is thereby established for the energization of relayy 462 over front contacts of relays 463 and 443, whereby sequence switch 450 is energized in a circuit over back contact of relayV 452, front contact of relay 462 and sequence switch contact 453 bottom. Sequence switch 450 moves over position` 6 into position 10.

-When the sequence switch of the final selector reaches position 8, the wanted line undergoes a final test and the right-hand high-resistance winding of the test relay 464 which can only energize on a free line, even if the cutoff relay is provided with a shunt, is connected in a circuit over the cutoff relay 488, terminal 470 and sequence switch contact 459 top. 1f the line is tree, relay 464brings over its front contact in parallel to its high resistance winding its left-hand low-resistance winding, together with the winding of relay 462. The terminal oi? the wanted line is made busy whereas relay 462 is energized. Sequence switch 450, in reaching position 10, is energized in the circuit over front contact of relay 462, and the sequence switch moves over posit-ions 10 and 11, into position 12, in which an alternating ringing current is immediately sent to the station of the wanted line in a circuit over the sequence switch contacts 466 top and 467 bottom, including the ringing relay 460. Relay 452 is brought over sequence switch contact 468 bottom in connection with a `common interrupter 469, which when closed, causes the energization of relay 452. The sequence switch 450 is energized in the circuit over the'front contact ot this relav and contact 446 bottom and moves into position 13. 1n position 13 relay 452 is connected over sequence switch contact 471 with a further common interrupter 47 2. The two interrupters 469 and 472 are continuously operated, and are arranged to Aclose the circuit to ground at predetermined time intervals so that after the sequence switch 450 reaches position 12, it is brought after the lapse of a few seconds over positions 12 and 13, into position 14. The duration ot time in which sequence switch 450 remains in positions 12 and 13 and an instantaneous ringing current is sentto the wanted station depends upon the moment the sequence switch reaches position 12, and varies slightly according to whether at this moment the interrupter 469 has just opened its contact or is near to close it. The contact of these interrupters is closed for a time suic'ient to energize relay 452, and to cause the energization of sequence switch 450, but not sutiicient to maintain its en Aro'ization more than to move the sequence switch .from one position. 1n this manner the sequence switch 450 is held in position 13 for at least av time which elapses between the closure of the interrupter 469 and the following closure of interrupter 47.2.

When sequence switch 450 reacne's position 14, the direct connection of the ringing current is removed in opening sequence switch contact 466, and the connection of the subscriber line with the ringing source of current is now maintained over sequence switch contact 473 bottom and the common interrupter 474, which in selected time intervals connects in succession the circuit eithergto the source of ringing current or to ground. During the time sequence switch 450 is in positions 12 to 14, the primary winding of tone coil 477 is connected over sequence switch contact 476 bottom to a common interrupter, whereas the secondary windings of coil 477 are connected in bridge to the line over sequence switch contacts 444 top and 445 bottom. The cal-ling subscriber perceives thereby any indication that the ringing of the called party is proceeding. As soon as the receiver at the wanted station is lifted from the hook the ringing relay 460 is energized and causes over its ,front contact and sequence switch contact 446 top the energization of sequence switch 450 which starts from position 14 and moves into position 15 in which the ringing Icurrent supply is disconnected, and a through connection of the subscriber line is made over sequence switch contacts 473 top and 467 top to the Vtransmitter current supply bridge at the group selector. Relay 262 is thereby energized. Sequence switch 220 is energized in acircuit over the contact 229 top'and front contact of relay 262. Sequence switch 22() starts from position 11 and moves into position 12. 1f the number of the wanted subscriber number begins with the figure 2, and the wanted number is for example 2253, the thousands register 100 receives eight impulses from the dial Aand one impulse over contact 330 bottom Vof sequence switch 320. lhe register 100 is therefore in position 9. TWhen the fundamental circuit is `closed over relay 222 of the first group selector', the resetting of the hundreds register 110 begins lin the manner as has been described, and

when register 110 reaches position Othe following deenergizatlon of relay 355 provides a `circuit for the energization of register 100 iover contact 114 of register 110 and Contact 102 of register 100. rlhis causes register 100 to movefrom position 9 into 'position O, so that sequence switch 350 andthe relay 357 are energized on the next deenergization of relay 355. .The trip spindle of the first group selector has therefore made an additional step, and is arrested in its fourth instead of its third position, as has been previously described. 'The brush carriage of the first group selector searches nowin an even level for a free final selector.

lf the second figure of the wanted number is odd, for examplanumber 1353, register 110 receives from the dial seven'impulses and is arrested in its position 7. lVlien sequence switch 350 moves over its position 11/3, rela-ysf373 and 374 are enerquence switch contact 372 top. `After the units register 140 has been set up, the energization of relays 373 and 374 is maintained over contact 146 of register 140 and contact 354 of sequence switch 350. hen

sequence switch 350 passes over position 2,

register 110 is energized in a circuit over contact 112, contact 361 top of sequence switch and contact 116 of register 110. Register 110 maires an'additional step and takes the same position as if the next lower ffl even ligure has been dialed. rlhe trip spindie of the group selector takes therefore the same position, disrcgarding whether the second figure of the wanted number was even or odd, whereas relay 374 controls the trans-.

lation of the units on the final selector, causing the advance of the brush carriage to the second half of the terminal row. YVhen the brush carriage of the final selector is rot-ating and relay 355 controls the units register 140, lthe circuit of this register is maintained in position 0 over front contact of relay 374 and contact 143 of register 140. Register 140 passes therefore over O position and starts a second rotation. When moving between position O and position 1, the holding circuit of relay 373 and 374 is now opened at contact 146 of register 140 and relays 373 and 374 are deenergized. When the unit-s register 140 completes vits second rotation and reaches position 0, they circuit is 'eX- tended over contact 143, backcontactv of relay 374 and contact 144 of register 140 to the sequence switch 350. The vbrush carriage of the final selector is therefore arrested at the second half of its terminal arc in a position corresponding to the position ofthe units register.

` lVhen, after a successful conversat-iomrthe calling subscriber restores his receiver on the hook relay 231 is deenergized, and sequence switch 220 is energized in a circuit over sequence switch contact 251 bottom, and back contacts of relays 222 and 231.` Sequence switch 220 starts from position 12 and moves over position 13 into position 17. When the sequence switch 220 moves over position 14 to 16, the metering battery' 259 is connected over rsequence switch contact 236 bottom and left-'hand back Contact of relay 224 to terminal 238, whereby the meter 208 of the calling subscriber line is operated. In position 17 yof sequence switch`220l the power magnet 241 of the brush carriage 'of the first group selector is again connected in the circuit over sequence switch contact 254 bottom, vbach contact ofhrelay 2312, contact 227 top `of sequence switch`220 land contact 282 bottom of sequence switch The brushcarriage rotates until its home Contact lll) and back contact ot relay 4.52.

269 is reached, whereby relay 232 is. energized in a circuit over contact 269 and sequence switch eontact- 226 top. rlhe power magnet 241 is disconnected, whereas sequence switch 220 is .energized in the circuitover the front contact of relay y232. in pas allel to the sequence switch 226 is also connected over its contact 233 top the holding magnet 245. rllhe brush carriage is arrested whereas sequence switch 220 starts Jfrom position 17 and moves into position 18.

After sequence switch 220 leaves position 12 thebrushes or" the group selector are disconnected at the sequence switch contacts 228, 256 and 255, relay 443 at the i'inal se lector is deenergized and sequence switch 450 is energized in a circuit over contact 4:38 top and baclr contact ot relay 443. Sequence switch 450 starts from position 15 and moves into position 17. Notwithstanding the deenergization of relay 443, the circuit containing test relays 462 and 464 is maintained closed over sequence switch contact 478 top and the called line is maintained busy. In position 17 sequence switch 450 relay 452 is brought over sequence switch contact 466 bottom, in connection with the called line, and it the calledsubscriber has not restored his receiver, relay 452 isener` gizedV overI the subscriber line in a circuit including sequence switch contacts 467 and 445. Sequence switch 456 is held in position 17 and lamp 481 is connected in a circuit over sequenceswitch contact 4.46 top and front contact of relay 452, displaying a guarding signal. When the calledr subscriber has also restored his receiver, relay 452 is deenergized and sequence switch 45() is energized in the circuit over contact 453 Sequence switch 450 starts from position 17 and moves into position 18 in which the power magnet 461 of the brush carriage is energized in a circuit over sequence switch contact 456 bottom, baclr contacts of relays 462 and 452. The brush carriage rotates until its home contact 4:37 bottom is' closed, whereby relay 452 is energized in a circuit .over contact 457 bottom and sequence switch contact 468 top. rl`he power magnet 461 is disconnected whereas sequence switch 450 is energized in the circuit over its contact 446 and front contact of relay 452. 1n parallel to sequence switch 450 is the holding magnet connected over its contact 458; the brush carriage is arrested, whereas sequence switch 4.30 starts from position 18 and moves into position 1.

After the release otra connect-ion, sequence switch 220 of the cord remains in position `18 until the second cord of the pair of cords is engaged in la' call. Vlhis arrangement is best shown in Figure 7 in which relay 272 corresponds to relay 262 in the cord of Fig. 2; sequence switch 270 corresponds to sequence switch. 280, et Fis and. contacts 274 and 276 correspondk to sequence switch contacts 244 and 256 of sequence switch 220. while contacts 278 and 279 correspond to sequence switch-contacts 288 and 289 ot scquence` switch 280, and wires 271 and 275 correspond to wires 291 andl 292. Assuming the second cord to be engaged in a call, sequence switch 220 provides in position 18 a circuit for the energization of sequence switch 280 over contact 244 bottom ot -sequence switch 220, wire 291, and a contact on the second cordV corresponding to sequence switch contact 289. Sequence switch 280 rotates and moves into position 10. ln passing position 91/2, a circuit is closed for the energization ot relay 262 over contact 256 bottom of sequence switch 220 and contact 288 top ot sequence switch 280. Sequence switch 220 is thereby energized over front contact ot' relay 262 and sequence switch contact 229. Sequence switch 220 starts from position '18 and moves into position 1 where-- by contact 244 is opened before sequence switch 280 reaches position 10.

1f the called subscriber is the first to restore his receiver on the hook, relay 262 in the cord is deenergizedk and sequence switch 220 is energizedfin a circuit over back contact of relay 262 and sequence switch contact k2:58 top. Sequence switch 220 starts :trom position 12 and moves into position 13. The circuit over the brushes of the rst group selector is thereby disconnected at sequence switch contacts 228, 256 and 255. The final selector is released, while the sequence switch of the cord remains in position 13 and the calling line is heldbusy until the calling subscriber restores his receiver and relay 231 is deenergized. Sequence switch 220 is then energized over back contacts of relays 231 and 222.

It the wanted line has been found busy and the test relays 464 and 462 have not been energized, when sequence switch 450 ot the inal selector moves over position 8, the sequence switch 450 is arrested in position 10, in which the primary winding of the busy tone coil 477 is connected over sequence switch contact 476 to abusy tone interrupter. The secondary winding of the busy tone coil 477 is thereby brought in bridge to the line, and the calling subscriber receives a busy tone. When the subscriber restores his receiver and relay 231 is deenergized, a circuit is established for the energization of the lett-hand winding et metering hindering relay 224 including back contacts of relays 231, and 222, contact 251 top of sequence switch 22() in position 11. Relay 224 disconnects at its left-hand back contact the circuit for relays 235,213 and 207, while over aholding circuit is provided the lett-hand front contact ot relay 224 for its lett-hand winding. Over the right-hand :front contact of relay contact 282 bottom of sequence switch 28M Sequence switch 220 starts from position 11 and moves over-positions 12 and 13 into position 17. rlhe purpose ot resistance in the circuit ot the local Contact 265 of' sequence switch 220 is to hinder the de- -energization of the right-hand winding et relay 224. After the disconnection of the group selector, relay 443n is de'energized and sequence switch 450 is energized over back Contact of rel-'ay 443, starts 'from position 10 and moves intoV position 1l, in which the power magnet V461 is energized in a circuit over Vsequence switch contact 456 and back contacts of relays 462 and The brushesY are restored to their positionot rest, whereby after Contact 457 bottom is closed, relay 452 is energized, causing the energization of sequence switch 450 over front contact of relay 452. Sequence switch 450 starts from positionV 11 and is maintained energized in positions 12 to 15nover back contact of relay 443, while in position V17 sequence switch 450V is energized over back contact of VVrelay 452 and moves into position 18, where relay 452 is again encrgized over Contact 457, so that sequence switch 4504 is energized over front contact of relay 452 and mo-ves into position l.

Since YYsequence switch 220 is held in position 11, whether the wanted line is busy or a ringing current is sent to the wanted station, relay 224 is energized it the calling subscriber' gives up the connectionV beto-re the called subscriber has answered. The

release proceeds thereforeV without metering if the sequence switch ot the final selectorV is' in its ringing position and the called subscriber does not answer.

It the called number belongs to a private branchY exchange, relay 463 tests in position 6 of sequenceV switch 450 the terminal to which the brushes of the final selector have been brought under the control ot the register set. Assuming the first private branch exchange line busy, relay 463 rcmains deenergized.l Power magnet 461 is energized ina circuit over sequence switch contact 456 bottom and back Contact of relay 462. The brush carriage rotatesaid and a tree line is searched for in reaching which relay 463 is energized. During the time the brushesl move from one terminal to another, relay 462 is shortcircuited over sequence switch contact 449 top of sequence switch and contact 457 top oi the brush carriage. As soon as the brushes are centered at the terminals of a free line and Contact 457 is' opened', relay 462 is energized, and sequence switch 459 is advanced from position 6'. vIt ail lines to the private branch exchange are busy, relay 463 is energized on the terminal of the last line, and through resistancel 489. Onthe repeated test in position 8 of sequence switch 450, relay 464 remains deenergized. Sequence switch 450 is arrested in position 10 and a busy tone is given to the called station. Through the repeated test on a iinal selector for private branch exchange lines, it is enabled to connect the relays 463 and 464 in succes sionfin the test circuit instead of in parallel or in series, so that sufficient energy is secured in the circuit for the energization ot these relays.

A connection can be immediately released at any stage of the progress or" the selection. In the first instance, a premature release can take place it two secon-d line finders happen to stay on the saine terminals, and relays 234 oi" both cords may become simultaneously energized whereby the relays 232 may also energize, and the sequence switch 220 of both cords may start from position l. 7h-en sequence switch 220 passes between positions 1 and Y3, the circuit for the higlr resistance winding of relay 234 is opened at contact 227 bottom. Relay 234 is not able to maintain its energization over its left-hand winding' ii' the current over res-istance 217 is divided in two branches. -Relay 234 is thereby deenergized, causing the deenergization of relay 232, whereby the lefthand win-dinger relay 224 is energized in a circuit o-ver'sequence switch contact 254 top, back contact of relay 232, sequence switch contact 229 bottom and contact 263. Relay 224 maintains its energization over its left-hand fron-t contact and left-hand winding, and hinders the energization of relay 235. Sequence switch 220 is arrested in position 4 in which sequence switch 280 is energized in a circuit, as lhas been described, and rotatesV until arrested' either on the terminals of a free register set, in which relays 234 and 232 are energized, or in position 10, wherebyV when passing position 9% a circuit is provided for the energization of sequence switch 220 over contact 239 of Sequence switchr280 and rightdiand front contact of relay 224. Sequence switch 220 starts from position 4 and completes then its cycle of operation without disturbing the calling line, or an engaged register set. Then sequence-switch 220 reaches position 18, sequence switch 280 is energized over contact 288 bottom and contactr244 ot sequence switch 220. Sequence switch 280 moves into its position 1.

l/Vhen a release is started during the time the searching sequence switch 280 is rotating, not Vnding ai free register, relay 231 is dcenergize-d, and relay 224 is energized in a. circuit over back contacts of relays 231 and 222 and contact 251 of sequence switch 220 in position 4, The calling line is immedi-V ately given tree, and when sequence switch- 280 reaches position 91/2, sequence switch 220 is energized in the circuit over contact 289 of sequence switch 280. The release is com'- pleted as has been described. Iihen a release is started, after the cord has been brought in connection with a free register set, relay 325 remains deenergized for a longer time than on a last opening at the dial. It relay 325 is not energized when sequence switch 320 being started through the energization of relay 323, reaches position 3, relay 334 is energized, sequence switch 320 moves over position 3 and, in passing position 5, relay 325 closes a circuit for the energization of relay 339 over contact 348 top of sequence switch 320 andbaclr cont-act of relay Relay 222 in the cord is energized in a circuit over front contact of relay 339, contact 37 6 top ot sequence switch 350, wire 296, contact 286 of sequence switch 280 and Contact 247 of sequence switch 220, so that sequence switch 220 is started from position 5 and moves into position 6. In the meantime sequence switch 350 has been started from position 1 as soon as sequence switch 320 has reached position 7 and the circuit for relay 222 is opened at contact 376 of sequence switch 350. Relay 222 is -deenergized and sequence switch 220 moves into position 7 in which relay 222 cannot become energized since the back contact of relay 339 is opened, so that sequence switch 220 moves over position 7 into position 8, in which the left-hand winding of relay 224 is energized in a circuit over sequence switch contact 251 top. In position 8 of sequence switch 220, relay 232 is energized in the circuit over the home contact 269 of the brush carriage, and conta-ct 226 oit sequence switch 220. The energization of sequence switch 220 is maintained over the front contact of relay 232 and sequence switch contact 227. Sequence switch 220 moves over position 8. In positions 9 to 13, the sequence switch 220 is maintained energized over right-hand front contact of relay 224 and contact 227, and in position 17 over front contact of relay 232. A

Then the release begins at thetime the brush carriage of the group selector is rotating, searching for a free trunk line to a final selector, the energization of relay 339 causes the -de-energization ot relay 222, sequence switch 220 Starts from position 7 and moves into position 8 in which relay 224 is energized. The power magnet 241 remains energized, wher-eas the left-hand winding of test relay 234 is disconnected at the right-hand back contact of relay 224. rIhe brush carriage continues to rotate without testing the terminals of the trunk lines, and after the brushes reach theirposition ot rest, relay 232 is energized in the circuit over home Contact 269, and the sequence switch is advanced over positions 8 t0 17, as has been described. vShould a release begin at the time sequence switch 220 is in position 9, and the fundamental circuit is extended to th-e following selector, the energization of relay 359 causes the deenergization of relay 222. Sequence switch 220 is energized in position 9 over back cont-act ot relay 222. In position 10, the energization of sequence switch 220 is maintained over back contact of rela-y 262. Relay 224 is energized as soon as the sequence switch reaches its position 11.

When the release is started before the dialing is completed, relay 339 is energized in one of the positions 5, 9 or 12, of sequence switch 320, whereas when the connection is given rfi at the calling subscriber station after the wanted number has been dialed, but before the selection is completed, sequence switch 320 is energized in position 16 over Contact 348 bottom and back contact of relay 325. In position 17, relay 339 is energized in theV circuit over sequence switch contact 348 top and back contact of relay V325, so that relay 222 in the cord is deenergized. At contact 342 top of sequence switch 320, the back contact of relay 359 is connected to ground and the circuit is established for the resetting of the registersf should they not be in their position O.

When a premature release is made Kat a stage in which sequence switch 220 is in position 7, and relay 224 is then energized, sequence switch 220 remains in position 8 until the brush carriage is restored to its position of rest. During all the time the brush carriage is restored, relay 222 remains connected over sequence switch contact 246 top to wire v293. t is therefore 'desirable that the register set snall not be given free and shall not be taken for a new call until contact 246 of the cord which has been released is opened. If the sequence switch 350, started from position 7 atter the registers have been restored, reaches po sition 18 bet-ore contact 246 of sequence switch 220 is opened, a circuit is established for the encrgization of relay 326over back contact of relay 323, contact 368 bottom oi" sequence switch 350, wire 293, contact 246 top of sequence switch 220 and winding of relay 222. Sequence switch 359 is held in position 18 until Contact lis opened, and relay 326 is deenergized.

IVhen the release is started after the group selector has obtained connection with the terminals of a tree inal selector, and sequence switch 450 has lett position 1 through the closure of the fundamental circuit at the register set, relay 452 is deenergized as soon as the relay 357 opens the fundamental circuit and enables sequence switch 450 to pass over positions 2 and 5 and to disconnect resistance 442 before the funwould be released.

damental circuit can be again closed, should the terminal oi the final selector immediately be talen by another cord.

The fundamental circuit may be opened at the moment the brush carriage or" a final selector has started from its position of rest, and contact 457 bottom has not been opened, whereby' the brushes may be arrested in the line .with the trip spindle. Sequence switch 450 would thereby pass over positions 6 and 11, and when in position 12 the trip spindle is restored in the well-known manner to its position oi rest in energizing magnet 44,8 in a cii'cuit over sequence switch contact 447 top and trip spindle contact 455 bottom, the latches of several brush sets The circuit of the final selector is therefore so arranged that whenever its sequence switch 450 passes over positions 8 to 9, a check is made whether the home contact is opened. It this is not the case, relay 452 is energized in the circuit over contact 457 bottom and the power magnet 461 is energized in the circuit over contact 456 top of sequence switch 450 and front contact of relay 452. The brush carriage is moved out until contact 457 is opened, so that sequence switch 450 is arrested in position 11 and the brush carriage is restored to its position ot rest. In all premature releases the operation of the meter 208 on the calling line is hindered through the disconnection of the metering battery 259 at the left-hand back contact of relay 224.

TWhen the dial on the subscriber station is erroneously set up to a higher number than the capacity of the exchange, and the first figure dialed is different from figure 1 or 2, the register 100 in the. exchange takes a position different from position 9 or 0. Should the subscriber notice the error and restore his receiver for a short while, the prermature'release will take place as has been described, and after the receiver is again removed, the calling line will obtain a connection with another cord. It the subscriber does not notice his mistake, he obtains a connection in the exchange over a special line to the supervisory operator who calls the attention of the subscriber to the error made. it register 100 takes a position different from position 9 or 0, sequence switch 350 cannot start from its position 1 after sequence switch 320 reaches its position 7, since the circuit for the energization of sequence switch 350 is maintained opened at contact 103 of register 100. Also, registers 110, 130 and 140 are hindered trom receiving impulses from the stepping relay 325 through the opening of contact 105 on register 100, and these registers remain. in their position 0, wl1ereas after each series of impulses from the dial, relay 334 is energized and the sequence switch 320 is advanced to its next position. After the subscriber completes the dialing, and sequence switch 320 moves into position 16, sequence switch 350 is energized in a circuit over contact 363 and contact 341 bottom of sequence switch 320. Sequence switch 350 starts from position 1 and moves into position 3. The fundamental circuit is then closed to the group selector, and its tri-p spindle when rotating controls the resetting of register 100 to a level corresponding to the-first ligure dialed. Since the following registers are in their position 0, a

number is selected consisting of three figures of which the iirst is the same as the first figure dialed and the remaining figures are zero. The lines 300, 400 and so on are reserved in the directory, and are connected to the desir ot' the supervisory operator, and the operator when communicating with the -ubscriber, knows which iirst figure the subscriber has erroneously dialed. One of these special trunk lines 502, 503, 504 leading to the supervisory operators position is shown terminating in the contact bank of the final selector in Fig. 5. When the connection is extended to the operators position relay 505 operates in a circuit includ- -ing relay 454. Relay 505 closes a circuit for lamp 506, notifying the operator that a call is waiting her attention.

Each regis-ter set is provided with a key 301 at the complaint operators position, and a subscriber who is unable to control the registers due to a disturbed dial etc., is able to obtain a connection with the complaint desk in removing'the receiver from the hook and waiting some time after he receives the dialing tone. A common timing arrangement for delayed signals is provided in the exchange, as shown in Fig. 6. lihen a register is attached to aV cord, a guarding lamp 344 lights in the exchange in a circuit over contact 345 of sequence switch 320. When sequence switch 320 passes position 2, a circuit is temporarily established over 'contact 327 bottom of sequence switch 320,

the left-hand winding of relay 392 and back contact of relay 393.V Relays 392 and 393 are common for several register sets. @ne of the windings of relay 395 is thereby energized over sequence switch contact 345 top and guarding lamp 344. Relay 392 when energized, provides according to the position of sequence switch 390, a circuit either over its left or its right-hand freni Contact, its right-hand winding, right-hand back Contact and winding of relay and lefthand frontcontact of relay 395. Relay 393 is thereby energized, disconnecting on its left-hand back contact the. operative winding of relay 392 and providing over its right-hand front contact a locking circuit t'or its winding. Over the left-hand front Contact of relay the right-hand winding of relay 392 is maintained energized,

Relay 394, common for a large number of register sets, is connected in a circuit over right-hand front contact of relay 395 to a common interrupter 399. vThe interrupter 399 provides at given time intervals the closure of the circuit for relay 394 which is therefore energized each time the interrupter 399 is closed, and sequence switch 320 of a register set is in position 3. Relay 39-1L provides a circuit for the energization of sequence switch 390 over back contact and right-hand winding of relay 398 and front contact of relay 394. rihe left-hand winding of relay 393 is thereby connected in parallel to sequence switch 390,v and the differentially wound windings of relay 393 remain deenergized. Sequence switch 390 is energized, starts from the `position in which it happensl to stay, and in closing of its local contact 391, provides a shunt around the right-hand winding of relay 393, the left-hand winding of which is then energized.- The sequence switch 390 moves in the next position, whereas relay 3931emains energized as long as relay 39t'is energized over the interruptor 399. Since sequence switch 390 is arrested in a number of positions, it completes slowly a cycle of operation in a predetermined length of time, while interrupter 399 which is driven from the common power shaft can be comparatively quicker. On contacts 396 and 397 of sequence switch 390 the energization of relay 392 is maintained until sequence switch 390 starts from position 15 and movesy into position 1. When `relay 392 is deenergized, a circuit is prepared for the complaint lamp 308 individual to the registerV set over contact 340 of sequence switch 320, and back contact of relay 392. The closing of this circuitis delayed until sequence switch 390 again reaches position 11 and'contact 397 is again closed. TheA lighting of the lamp 303 .beforev the complaint operator is therefore delayed at least the time necessary for sequence switch 390 to move from position 15 into position 11. lf sequence switch 320 passes over position 2 and relay 392 is energized when sequence switch 390 is ink a position earlier than position 15, the lighting of the lamp 303 is still further delayed. When sequence switch 320 in al regular connectionv leaves posit-ion 3, relay 395 is deenergized and the lholding circuit for relay 393 is opened. Lamp 308 is now displayed befcre the complaint operator.

4The operator in noticing lamp 303depresses key 301, whereby the stepping relay 325 of the register set is brought in connection with a dial 302, whereas in'bridge to the calling line are now connected the windings of relay 303. The contacts on keys 301 are so arranged that iirst the dial is connected, then relay 303 is brought in parallel to relay Y325, and after that the two circuits are separated. Relay 303 .brings over its frontv contacts the wires 304:- of the operators telephone into connection with the calling line. The operator communicates with the subscriber, whereas the register is maintained undisturbed. The lamp 303 also serves to indicate the presence of a short-circuit across the subscribers line. If this is the case she can either directly notify the troubleman, or in operating her dial once, cause the advance of switch 320 to a later position in which a time alarm signal 500 is displayed before the troubleman by means of a circuit through contact 333 bottom and relay 501. If the complaint operator finds that the subscriber is not able to set up the register, and having ascertained that the subscriber has not dialed after he removed the receiver the last time, she sets up the register set according to the wanted number, from her dial and restores the key 301. The. registers then take positions according to the number dialed and control the setting up of the switches for the connection, whereby relay 325 is maintained energized over the subscriber line after key 301 is restored. l/hen the selection is completed, the register set is released, and the sequence switch of the cord is advanced into the position of a through connection which remains under the control of the calling subscriber.

is illustrating the construction and operation of a switch mechanism suitable for use in systems of this character, reference is made to the patent to F. R. McBerty No. 1,097,363, granted May 26, 1914.

What it claimed is:

1. In a telephone system, a` line, selective switches for extending said line, a register controlling mechanism for controlling said switches, means for associating the controlling mechanism with said line, means operated over the line to set said mechanism, an operators position, a signal thereat, and means operated following the association of said mechanism with the line if said mechanism fails to undergo its setting operation for rendering said signal effective.

2. In a telephone system, a line, selective switches for extending said line, a register controlling mechanism for controlling the movement of said switches, means for associating the controlling mechanism with said line, means responsive to impulses sent over said line for setting the controlling mechanism, an operators position, a signal thereat, and means operated following the association of said mechanism .with the line if said mechanism fails to undergo its setting operation for rendering said signal edective.

3. n a telephone system, a line, selective switches for extending said line, a common register controlling mechanism for controlling the movement of said switches, means for. `associating they controlling mechanism lin) with said line, means for associating said nrechanisn with one oi said switches, means operated over said linefor setting the contro-lling mechanism, an operators position,

a signal thereat,L means operated in response:

to the association of said mechanism with the line for 'rendering said signal effective, and means atthe operators position for setting said controlling mechanism. Y

il. In a telephone system,VV a subscrihers line, a selective switch for extending said line, a register controlling mechanism for controlling the movement ci saidY switch, means at the snoscrihens substation for sending impulses @ver the line, 'means responsive to such impnlses to set said mechanism, an operators position, a signal thereat, means operated bythe controlling mechanism 'tor rendering Ysaid signal effective, and impulse sending means at the operators position for setting said mechanism. i

5. In a telephone system, a snhscribers line, selective switches for extending` said line, a controlling mechanism comprising al plurality of registers for controlling the movement oi said switches, means controlled over -the siibscrihers line for varialoly setting said registers in accordance with desired designations, an operators position, a signa-l thereat, ymeans operated by the controlling mechanism tor rendering saidv signal eilective, and means at the operators position for variahly set-ting said registers Yin accord-ance with desired designations. f

6. In a telephone system, a line, selective switchesfor extending s aid line, a register controlling mechanism for controlling 'the movement of said switches, means for associating the controllingv mechanism with said line, means for vari'ably setting said controlling mechanism, an operators position, a signal thereatkand means operated by said mechanism at lthe end o'i a predetermined interval following the association of said mechanism with the line ior rendering said signal effective, f

7. In a 'telephone system, a line, selective switches for extending vsaid line, a common register controlling mechanism for controlling the movement of said switches, means operated 'upon the initiation of av call 'for associating the Vcontrolling mechanism with said line and with one of said switches, means for `variablysetting said controlling mechanism, an operators position, a signa thereat, and means operated atthe end o'i a predetermined Yinterval following the association ol saidV mechanism with the line for 'rendering said lsignal effect-ive;

S. In a telephone system, a sahscrib'ers line, a selective switch for extending said line, a register controlling mechanism for con-trolling the movement of said switch, means lor associating the controlling mechanism with said line, means opera-ted over said line for varialoly setting said mechanism, an operatorsi position, a signal thereat, means operated by said mechanism at the end of a predetermined interval following the association oli said mechanism with the snhscribers line for rendering said signal edective, and means controlled hy the operator ior variably setting said mechanism.

9. In a telephone system, a. snbscrioers line, selective switches for extending said line, a register controlling mechanism tor controlling the movement ot said switches, means for associating the controlling mechanism with vsaid line, means operated over said line for variably setting said mechanism, an operators position, a signal thereat, means operated by said mechanism at the end of a predetermined interval Vfollowing the association of said mechanism with the subscribers line Yfor 'rendering said signal effective, Vmeans for establishing a vtalking connection fbetween said line and the operators position, and means vcontrolled hy the operatorior vari'aloly setting said mechanism. i.

l0. In a telephone system, a subscriloers line, selective switches for extending said line, a register controlling mechanism for controlling the movement oit VYsaid switches, means for associating 'the controlling mechanism with the snbscribers line, means ttor varialoly setting said mechanism, anopera't'ors position, a signal thereat, a timing device Vrendered eileective hysaid mechanism in response "to the association of said mechanism with the subscribers line, and 'means opera-ted by said device after the lapseof a time intervallor rendering said ksignal ef.- 'ect'ive. Y

ll. In a telephone system, yan exchange having 'a plurality of lines, each line having an individual designation, selective switches, a 'register controlling mechanism, means for variahly setting said mechanism in accordance with said designations, means controlled by said mechanism for operating the selective switches to Iextend a calling line 'to a `desired line in the exchange, an yoperators position, and means for extending 'the callingY line to said operators posi-tion when said mechanism isset in 'accordance with a designation other than those of the lines of said exchange. l y y l2. In aV telephone system, a `calling'line, selective switches, a controlling mechanism comprising a plurality of registers, means for sending series of impulses over the calling line, each of'saidseries being eilective to set 4a 'corresponding one 'of said registers, means controlled lay said registers for lo-perating the selective switches to extend the calling line, an woperators position, and means operated in response to certain series of impulses for rendering the following selil-ll iso ries ineffective to set the corresponding registers, said registers being eEective in such a case to control the selective switches to extendthe calling line to the operators position.

13. In a telephone system, an exchange having a plurality of lines, each line having an individual designation, selective switches, a register controlling mechanism, means for variably setting said mechanism in accordance with said designations, means controlled by said mechanism tor operating the selective switches to extend a calling line to a desired line in the exchange, an operators position, a signal thereat, and means for operating said signal when said mechanism is set in accordance with a designation other than those of the lines of said exchange.

14. In a telephone system, an incoming line, a plurality of out-going lines, means including an automatic switch for extending said incoming line to a wanted outgoing line, a sender selectively vadjusted by impulses over said incoming line to control the setting of said automatic switch, means for connecting said sender to said incoming line, an operators position, and means for signaling said position when no impulses have been transmitted to said sender after its seizure.

15. In a telephone system, an incoming line, a plurality of outgoing lines, an automatic switch for extending said incoming line to a desired outgoing line, subscriber controlled means including a register sender and operator controlled means for causing said automatic switch to extend said incoming line to a desired outgoing line, said subscriber controlled means being normally effective to control the operation, a signal for indicating the necessity ot using the operator controlled means, and discriminating means for controlling said signal.

16. In a telephone system, a plurality of telephone lines, certain of said lines being provided with impulse transmitting devices, a register sender arranged to be variably controlled over a telephone line in response to the operation of said impulse transmitting device, means including automatic switches for interconnecting anyv one of said lines with any of the other lines, said automatic switches being controlled in accordance with the setting of said register sender, an operator controlled transmitting device for causing said automatic switches to interconnect a telephone line to any of the other lines, and a signal for indicating that the operators transmitting device must be used in completing a connection, and means for disabling said signal.

In witness whereof I hereunto subscribe my name this th day of February, A. D. 1919.

LIPA POLINKTWSKY.

In witness whereof I hereunto subscribe my name this 13th day of May, A. D., 1919.

GERALD DEAKIN.

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