US1576884A - Telephone system - Google Patents

Description

March 16 19-26. 1,576,884

- J. wlcKs TELEPHONE SYSTEII Filed Sept. 7, 1923' 9 Shae t 1 x v -Inuen John Hzcks Biz- March 16 1926. 1,576,884

'J. WICKS TELEPHONE SYSTEM Filed Sept. '7, 1923 9 Sheets-Sheet 2 --Inuan arr- Jul-m Jn/icks 9 Sheehs-Sheet J. WICKS TELEPHONE SYSTEM Inusn a Jczhn %4' 7%? I Filed Sept. '7, 1923 m rm March 16 1926.

' J. wlcKs TELEPHONE SYSTEM Filed Sept. 7, 1923 9 Sheets-Sheet 4 Juhn Inhcks [Q4 HT March 16,1926. 1,576,884

J. WICKS TELEPHONE SYSTEM John lnficks March 16 192s. 1,576,884

J. WICKS TELEPHONE SYSTEM Filed Sept. 7, 1923 9 Sheets-Sheet 6 'Marh l6 1926.

' J. WICKS TELEPHONE SYSTEM Filed Sept. '7, 1923 9 Sheets-Sheet 7 Inuezfz John Hicks March 16 1926.

J. WICKS TELEPHONE S-YSTEM 5 Filed S Dt 7. 1923 9 Sheets-S eat 8 .E'ZUEU DI Jqhn Hicks March 16 192s. I 1,576,884

J. WICKS TELEPHONE SYSTEM Filed Sept. '7. 1923 9 Sheets-Sheet 9 .Tnusn c7 Juhn Hwks Hwy:-

patented Mar. 16, 1926.

UNITED stares PATENT OFFICE.

JOHN WIGKS, OF OAK PARK, ILLINOES, ASSIGNOR, BY MESNE ASSIGNMENTS, TO AUTO- MATIC ELECTRIC INC., OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE.

TELEPHONE SYSTEM.

App1ication filed September 7, 1923. Serial No. 661,359.

To all whom it may concern Be it known that 1, Joint \VIGKS, a citizen of the United States of America, and a resident of Oak Park, Cook County, and State of Illinois, have invented tertain new and useful Improvements in Telephone Systems, of which the following is a specification.

The present invention relates in general to traffic intercepting equipment for use in connection with automatic telephone systems, but is more particularly concerned with intercepting equipment used in a multi-ofiice system; and the object of the invention is the provision of means for causing calls, usually intercepted by operators at the ofiice in which they originate, to be intercepted by operators located in a centralized office.

l-leretofore the usual practice, so far as applicant is aware, has been to provide in tercepting operators positions at each oiiice. Where the number of calls to be intercepted in anindividual o'lice are few calls cannot be economically intercepted. By trunking'these calls to a centralized oilice provided with in tercepting operators equipment a single operator may, during slack periods, efficiently handle all of these calls for several oilices. thereby effecting quite a saving in the number of operators required.

Referring to the drawings comprising Figs. 1 to 11, inclusive, Figs. 1 to 5, when laid out and arranged in the manner shown in Fig. 10, illustrate suliicient circuits and apparatus of an automatic telephone system to enable connections to be set up between a toll operator and a subscribers station by way of a toll switch train, andto also enable a calling subscriber to set up connections over a local switch train.

Figs. 1 and 7, when Fig. 7 is placed with the conductors at the right thereof in align ment with the correspondingly indicated conductors in the upper portion of Fig. 1 extending from relay group RG illustrate the necessary circuits and apparatus required for trunking calls, extended to a dead level of the first toll selectors, to call signal equipment at a centralized operators position.

When l igs. l to 5 and 8 are. laid out as shown in Fig. 10, Fig. 7 may be similarly used in conjunction with relay groups RG HQ and lit? to illustrate how calls to be intercepted from dead levels in selectors E.

F and dead line contacts in connector H, may be trunked to a centralized operators position.

Fig. 6 shows an intercepting operators cord circuit suitable for answering calls trunked to the intercepting operators position.

Figs. e and 8, when laid out and arranged in the manner shown in Fig. 11, illustrate sufficient telephone apparatus and circuits for switching a. subscribers line from connection with a line switch into connection with conductors terminating in call signal equipment.

Fig. 8 in conjunction with Fig. 9, when laid out and arranged as shown in Fig. 11, illustrates sufiicient equipment for answering and extending such calls to an operators position equipped with facilities for completing connections to automatic'or manual subscribers lines.

Referring more indetail to the drawings, Fig. 1 shows a portion of a toll line X terminating in a jack J, and having associated with it the usual relay equipmentrequired to control the call signal lamp 8 and the busy visual 7.

Y The left hand portion of the toll operators cord circuits, such as the cord circuit O, are the same as are usually used at toll operators positions, While the right hand portion of these cords are .modified to enable the operators to control automatic switches and to get answering supervision.

'The selector D is of the well known Strowger type and is wired in accordance with the usual two-wire practice.

The relay group RG is part of the equip ment used in intercepting calls extended to a dead level of the selector 1).

F '2 shows a toll transmission selector E with its associated relay equipment B. This-selector is mechanically the same as the selector D.

- The relay group RG is part of the equipment used for intercepting calls extended to a dead level in the selector E.

Fig. 3 shows a connector H, which is of the usual Strowger type, but which has its circuits so arranged that it may be operated either as a toll or regular connector.

F 4 shows. a line switch C, which is of the usual nonrestoring or rotary type. This switch is individual to the substation A which is of the usual type used in automatic practice.

A portion of a main distributing frame 421 is shown and has springs 422, 424, 426 and 428 for connecting the line of substation A with its line switch C, through the medium 01 the usual line protecting apparatus (not shown).

The connecting link or cord 0 is provided at one end with appropriate springs for plugging into the springs in the main distributing frame of any desired line, and when plugged in it disconnects a line from its connection with the connector banks and connects the conductors oi the line and the conductors extending to the connector banks to separate conductors in the cord. This cord is provided at its other end with appropriate plugs for connecting two of its conductors to conductors terminating in an answering jack at a local operators position, while connecting the other two of its conductors to the relay group RG In other words this connecting link 0 is for use in re-routing calls to and from subscribers lines which aretemporarily out of order.

Fig. 5 shows a calling station A, a line switch G, and a selector F, which are identical to the substation A, line switch 0, and selector D, respectively.

The relay group RG is part of the equipment used for intercepting calls extended to a dead level in the selector F.

Fig. 7 shows a line switch G and a master switch MS which are of the'well known Keith type. There is a line switch C individual to each of the relay groups RG RG etc. As is well known, the master switch MS is common to a number of the line switches, such'as C and is provided for maintaining all such idle line switches with their plungers positioned before idle trunks. These line switches have accessto trunk lines extending to and terminating in jacks, such as the jack J Fig. 6 shows an operators cord circuit 0, for use in answering calls which have been trunked via line switches, such as C from the various oflices in the system to jacks, such as J, located before intercepting positions in the centralized office.

OaZZs from a distant ,ofi'icc to subscribers lines.

In order to clearly describe the invention, it will be necessary to know just what operations take place when a toll connection is completed by the toll operator, and for this purpose it will be assumed that a call comes in over the trunk line X and that the operator proceeds to complete the connection.

When signalling current is transmitted over. the trunk line X from the distant exchange, a ring-up relay 1 energizes and completes a locking ,circuit for itself at its armature 3, and at this same armature completes a circuit for the call signal lamp 8 in the usual manner. The operator upon noticing the lighted condition of lamp 8 proceeds to answer the call by inserting the plug P of her cord circuit into the jack J, causing the energization of cut-oil relay 2 and sleeve relay 11, respectively. Reiay 2 upon operating, at its armatures 4 and (5, breaks both the energizing and locking circuits of relay 1. This relay, accordingly, deenergizes. Relay 2 at its armature 5 also completes a circuit for the busy signal 7 and its multiples to notify operators at other positions that this trunk line is in use to prevent it being seized for outgoing service. Relay 11 upon operating prepares a circuit for lamp l2 and relay 14, which circuit will be completed later. The operator may now throw her key K in listening position and converse with the distant operator to ascertain the number of the desired subscribers line. Assuming now that the station A is desired, the operator proceeds, after making the usual busy test, by inserting the plug P into an idle jack J, which is connected with conductors terminating in a toll selector D. This results in the operation of the line relay 26 over a circuit which may be traced from battery, upper winding of relay, resting contact of armature 55 and the said armature, tip side of jack J, tip contact of the plug P, through springs oi the key K, upper right hand winding of the repeating coil R, windingof the polarized relay 20, lower right hand winding oi the 1 said repeating coil, lower springs of the key K, ring contact of the plug P, ring side of the ack J conductor 57, armature 51 and its resting contact, and the lower winding of relay 26 to ground. The line relay energizes and completes a circuit for slow release relay 28 which also energizes. Relay 28 upon operating, at its armature 29, grounds release trunk 24, causing the energization of sleeve relay 22 of the operators cord circuit, and at its armature 31 prepares the usual operating circuit forthe series relay 34 and the vertical magnet Relay 22'upon operating, disconnects the tertiary winding of the operators head set. The current flow through the polarized relay 20 is in the wrong direction for it to operate at this time. The operator, immediately after plugging up the connec-' tion, throws her calling device key K, substituting the calling device S for the polarized relay, and operates her calling device 1 inaccordance with the first digit in the telephone number oi": substation A. hen the calling device is operated in accordance with the first digit of the number, a series of interruptions is produced in the circuit of the 1 armature 37.

-ment is busy or isnot busy.

line relay 26. Responsive to this series of 'mpulses, relay 26 deenergizes.momentarlly and at each deei'ierglzatlon sends an impulse to the series relay 34: and vertical magnet 85.. By the operation. of the vertical. magnet the switch shatt is raised step by step until the wipers 41--l-8, inclusive, stand opposite the level of bank contacts in which are terminated the trunk lines leading to the desired group ct toll transmissionv selectors, The slow acting relay 34 is energized in series with the vertical magnet and maintains its, armature continuously attracted throughout the vertical movement of the switch. As

soon the switch takes one vertical step a circuit also completed for stepping relay 86. This circuit extends from battery, winding o't the saidrelay, interrupter springs of motor magnet 38, oh normal springs 53, closed on first vertical step, working contact of armature 33 and the said: armature, and the grounded release trunk conductor 24. The stepping relay, upon energizing, completes a locking circuit for itself at its At the end. of the vertical movement ot the switclnseries relay 34 deenergizes and completes a circuit for the rotary magnet 38-, which. extends from the grounded release trunk conductor 24, armature 33 and itsresting contact, armature 39 and its working contact, and the winding of the rotary magnet 38 to battery. The retary magnet is accordingly energized and advances the wipers 4143, inclusive, into connection with the first set of bank contacts in the selected level. Near the end of its stroke the rotary magnet breaks the circuit oi the. stepping relay 36, which is accordingly deenergized to open. the circuit oi the rotary magnet. Both the stepping relay 36 and the rotary magnet 38 having deenergized, the operation now depends upon whether the test contact of thetrunk with which the test wiper 42 is in engage- If this trunk is busy its testcontact will have a ground potential upon it and a circuit will be established which extends from ground on the said test wiper 42, armature 40 and its resting contact, oi'l' normal springs 58, interrupter springs 50,. and: the winding of relay 30 to. battery. above circuit the stepping relay 86 is'again energized and again closes a circuit of the rotary magnet 38 which, in turn, operates to advance the switch wipers into engagenicnt with the next set of bank contacts.

rotary movement of the switch will cease.

By current flow over the Relay'54, however, energizesandi at its armature 40: connects the test w-iper'42 to. grounded. conductor 24: in. order tormake. the multiples ofthe test. contact 45 busy to: other switches, opens. a point in. the circuit of releasemagnet 30'at its armature 52, and; at armatures151 and 55 disconnects the=line relay. 26 from inbridge of the trunk coirductors 56: and 51 andsubstitutes the con.- ductors 8'1 and 88across whiclr are bridged the. windingset line. relay 141 otthe toll transmission. selector Line relay 141- is energized and. completes at circuit for slow' acting release relay 143. Upon operating; relay 143 at. its armature 147 connects ground to release trunk conductor 82. It will be understood that this ground is applied before the slow relcaserelay 28 in the selector D has deenergized, and therefore. this latter switch is prevented from releas ing at this time;. Relay 1'43ialso' at its armature 146. prepares a: circuit for the seriesv relay 150. anch vertical magnet 1 49 in the usual manner..

The I tell operator may now operate hen calling. device: in accordance witlr the second digit of the desire-cl. number. By this operation a series of: interruptions isprodiiced in. the circuit: of line. relay 141.. Art! each.

d'eenergization, animpulse:oflcurrent is sent.

over a circuit extending from: the grounded. armature 14.4 and its resting. contact, armature 146 and it'sworking c0nt'act,.armature 155 and its resting'contact, windings of re lay 150,. anditheverticali magnet: 149 to bat tery.. The operation of thevertical: magnet 149 causesz'theswitch wipers to be raised opposite thedesired: group. of" bank contacts. Theslovv. acting relay' 150 operates and remains energizedl throughout the ver'' tical movement of. the switch. Slow relay 150 at springs. controlled by its: armature- 148 closes a circuit for relay 1081' Relay? 108- upon operatin at its armature 109 completes a locking circuit; for: itself i'ndepend ent of. the relay 15.0, at its armature. 1110' opens a point in the operating: circuit; of reversing relay 128-, and atiits'armatures106. and 107 disconnects the winding of: the su pervisory relay 112 from in. bridge ott'hes trunk line and substitutes the resistance ele ment 115 to improve an operating: circuit= which will be traced later. As. soon. as the wipers of the switch are-raised one step the: off normal springs 134 and13-5 close, completing a. circuit for stepping relay 162-as follows: ground, working contact of armature and the said armature, working contact of armature 143 and the said armature, off normal springs-134, and the winding of relay 162 to battery. Relay 162 upon operating, at its armature 164, completes a locking circuit for itself, and at its armature 163 closes a point in the operating circuit of the rotary magnet 166. At the end of the vertical movement of the switch, the slow relay deenergizes and at springs controlled by armature 148 completes an initial energizing circuit for the rotary magnet 166. This circuit extends from grounded working contact of armature 145 and the said armature, springs controlled by armature 148, armature 163 and its working contact, and the winding of rotary magnet 166 to battery. The rotary magnet in operating moves the wipers 171174, in elusive, into engagement with the first set of contacts'in the selected level, and near the end of its stroke breaks the locking circuit of stepping relay 162 at interrupter springs 161. Stepping relay 162 deenergizes and at its armature 165 closes a point in a circuit including the test wiper 173. If the trunk line associated with the first contact set is busy, the test contact engaged by the wiper 173 will be grounded and a new circuit will be completed for stepping relay 162 extending from grounded wiper 173, resting contact of armature 165 and the said armature, armature 156 and its resting contact, interrupter springs 161, off normal springs 134 and the winding of stepping relay 162 to battery. Stepping relay 162, upon energizing, again completes the previously described circuit for rotary magnet 166. This alternate operation of stepping relay 162 and the rotary magnet take place as long as the wiper 173 engages grounded or busy test contacts. As soon, however, as the wiper 173 engages an ungrounded test contact the stepping relay 162 does not energize. Switching relay 152 which has previously been short circuited by the grounded test wiper 173 now operates over the following circuit: grounded working contact of armature 145 and the said armature, winding of switching relay 152, interrupter springs 161, off normal springs 134, and the winding of stepping relay 162 to battery. The resistance of relay 152 is Very high compared with that of relay 162, and therefore relay 162 does not energize at this time. Relay 152, however, operates and at its armature 156 conn'ects direct ground to the wiper 173 to make this trunk busy to other selectors, such as E, at its armature 154 connects the, wiper 172 to the conductor 151 for a. purpose which will be later made clear, and at its armatures 153 and 157 extends the trunk conductors 132 and 133 into connection. with the conductors 167 and 176..

which extend to the relays 312 and 326 of the connector H. Relays 312 and 326 now operate over a circuit extending from battery, upper windings of said relays, resting contact of armature 331 and the said arma ture, conductor 167, bank contact 175, wipc-r 171, working contact of armature 153 and the said armature, working contact of annature 139 and the said arn'iature, armature 118 and its resting contact, upper right hand winding of the repeating coil R, resistance 100, armature 107 and its working contact, resistance 115, resistance 101, lower right hand winding of therepeating coil, resting contact of arn'ia'ture 117 and the said armature, conductor 133', armature. 157 and its working contact, wiper 174, bank contact 178, conductor 170, armature 334 and its resting contact, and the lower winding of relay 312 to ground. Relay 312 upon operating completes a circuit for relay 314 which also operates, at its armature 315 grounds the te t conductor 362 tern'iinating in bank contacts of local selectors, such as the selector F (Fig. 5), at'its armature 317 applies ground to the conductor 169, and at its armature 316 prepares an operating circuitfor the vertical magnet 311 and series relay 318 in the usual manner. llelay 326 upon operating, at its armature 327, prepares a point in the operating circuit of relay 332, removes one of the multiple ground connections from conductor 16%). and com pletes a locking circuit for itself at arma ture 328.

The connector H is now ready to be operated under the control of the. calling de vice S. lVhen the dial is actuated in accordance with the next digit in the number of the subscriber at substation A, a series of interruptions is produced as before in the circuit of relay 141 of the toll transmission selector E causing armature 139 to retract a corresponding number of times to bring about a series of deenergizations of the line relay 312. At each deenergization. the line relay 312 transmits acurrent impulse through the series relay 31S and the vertical magnet 311 to battery. This circuit may be traced from the grounded arn'iature 313 and its resting contact, armature 316 and its working contact, oil: normal springs 360 and 322, windings of the series relay 31S, and the Vertical magnet to battery. This is the circuit over which the first impulse is transmitted. At the first upward step of the switch shaft, however, the oil normal springs are shifted and the circuit extends from the working contact of armature 316 to oil normal springs 360 and 361, armature 319 and its working contact and the windings of relay 318 and Vertical magnet 311 to battery. By the operation of the vertical magnet, the switch shaft is raised step by step until wipers 356358, inclusive, stand opposite the level of bank contacts in which the line 01" substationA is terminated. 'The slow acting relay 318, which is energized in :series with .the vertical magnet, maintains .its armature attracted throughout the verticaloperationof the switch. When this-re 'lay energizes at the beginning of the vertical movement, it closes the following circuit for the ring cut-oft relay335 in multiple with the holding circuit of relay 326: From grounded conduct-or 302, armature .323 .and its working contact, working contactot armature 320 and the said armature, and the lower windingof relay 335 "to battery. Relay 335 upon operatin at its armature 337, completes a locking circuit for itself inde sendent of the armatures controlled by relay 318 and 326, and :at its . armatures 336 and 338 disconnectsgenerator .and ground from the conductors 362 and 363. At the end of the vertical movement of the switch, the slow acting relay 318 do.- energizes and prepares the connector ioroperation to move its wipers in a rotary dimotion.

The toll operator may .now operate the dial of her cal-ling device S in accordance with the final digit'o-f thecalled subscribers number. The interruptions produced are repeated as before through the medium of line relay 141 and cause another series of deenergizations of the line relay 312 of the connector H. At each -deenergization the line relay 'now sends a current impulse through the rotary magnet 364 over the "following path: Grounded armature 313 and its resting contact, armature 316 and its working contact, oii' normal springs 360 and 361, armature 319 and its resting contact, resting contact of armature 342 and the said armature, armature 352 and its resting contact, and the winding-oi rotary magnet 364 to battery. In response tothese impulses, the rotary magnet operates to rotate the wipers 356-358, inclusive, into engagement with the particular set of bank contacts in which the line of substation A terminates, these bank contacts being :the contacts indicated in the drawing by the reference numerals 366, 367 and-368. The slow acting relay 345 isenergized in parallel with the rotary (magnet and retains its armatures attracted throughout the rotary movement of the switch. At'its armature 346, relay 345 connects the test wiper 357 to the winding of the busy test relay 340, and at its armature 347 closesa shunt around the armature 342 ot'irelay 340 to .guard against the possibility of the said relay beingmomentarily energized while the-test wiper 357 is passing over busy test contacts.

(Jailed Zine busy.

In order to afford an opportunity to explain the operation of the busy test cirgrounded ztest contact 367, wiper-357, arma- .ture 346 and :its working contact, resting contact of -'armatu-re 355, and the winding of test relay 340 to battery. The test relay is energized over the above circuit, and when the slow acting relay 3.45 deenergizes vat the end of the rotary anovement of the switch the test relay becomes locked up by means of the following circuit: grounded conductor 302, armature 341 and its workmg contact, springs controlled by armature 346, resting contact of armature 355 and the said armature, and the winding of test 'relay 340 to battery. Relay 340 at its armature 342 opens a point in the operating circuit of slow relay 345 and rotary magnet 364, and at its armature 343a leadfrom the busy machine Q is connected to the lower line conductor 170 by way of springs controlled byarmature 334, conductor 325, condenser :305,.springs controlled by .the armature 30-8, and the resting contact of armature 3'34 and the said armature to conductor 170. It the operator or subscriber in the distant office is listening in on the trunk line they will hear the busy signal, which will inform them that the call cannot be immediately completed.

' The toll operator at the rilocal-oflice having dialled the complete number, now restores the .keyfK :to normal, again inserting the polarized relay 20in bridge of the extended trunk'line. Since the line called is busy the direction of current flow in the conductors 56 and 57 Elias not been changed and relay 20 tl1ere1 -ore doesnot operate in the proper direction to cause the lamp 19 to glow. The operator is therefore notified of the busy condition of the called line by the lamp 19 not glowing and also by the busy tone it she still .has her key K thrown in listening position. v

The operator now withdraws the plugs of 1 the cord 0 from the associated jacks. The removal of the plug P form the jack J causes the circuit of line relay 141 of the selector E to be opened. This relay upon deenergiz'ing, at its armature 144, breaks the circuit oft-release relay'143.and completes a circuit for relay- 1'58 and the release magnet 168., which may be traced as follows: grounded armature 144 .and its resting con- .tact,.armature 146 and itsresting contact, oii' normal springs 135 and the windings of re lay .153 and of the release magnet in multipleito battery. The operation of magnet 168 causes the selector E to restore to normal. Relay 158 upon Operating, at its armature 159 completes a circuit for itself and for the releasemagnet independent of the ground applied by the relay 141 so that the release of selector E cannot be prevented by the selector being seized before it has fully restored. Relay 158, at its armature 160, introduces a high resistance in series with the lower winding of relay 141 to prevent the reoperation of relay 141 by the discharging of condenser 197 when the circuit of 141 is opened, and at armature 165 disconnects the wiper 173 from the winding of switching relay 152 while the switch is restoring. Belay 143 upon retracting its armatures removes ground from the release trunk conductor 82, causing the release of the switching relay 54 of the selector D. Relay 54 at its armature 52 completes a circuit for the release magnet 30, causing the selector D to also restore to normal. Relay 141 at its armature 139 also opens the circuit of line relay 312 of the connector H. The line and release relays 312 and 314 therefore deenergize and complete a circuit for the release magnet 330. This circuit eX- tends from the grounded armature 313 and its resting contact, armature 316 and its resting contact, armature 309 and its resting contact, 01f normal springs 323, and the winding ofrelea-se magnet 330 to battery, causing the connector H to restore to normal.

Called Zine idle.

It will now be assumed that the line of substation A was idle when the connector seized it. Under these conditions the test wiper 357 finds battery potential instead of ground, and the test relay 340 therefore does not energize. Upon the deenergization of slow relay 345 a moment later, a circuit for switching relay 348 is completed as follows: from grounded release trunk conductor 302, armature 341 and its resting contact, upper winding of switching relay 348, resting contact of armature 346 and the said armature, wiper 357, test contact 367, conductor 371, winding of cut-off relay 406 of the subscribers line switch, and the rotary magnet 413 to battery. Due to a mechanical interlocking device on the line switch C, relay 406 only operates its armatures for a sufiicient distance to disconnect the normal battery and ground connections from the called line. Relay 348, however, fully operates, and at its armature 353 completes a locking circuit for itself. This locking circuit may be traced from the grounded working contact of armature 145 of relay 143 (Fig. 2), working contact of armature 156 and the said armature, armature 165 and its resting contact, wiper 17 3, bank contact 177, conductor 169, armature 353 and its working contact, and the lower winding of switching relay 348 to battery. The relay 348 at armature 351 applies direct ground to the test wiper 357 to make the test contact 367 busy to other connector switches, at its armatures 352 and 355 opens points in the operating circuits of the motornagnet 364 and test relay 340, respectively, and at armatures 349 and 354 close points in the talking circuit. Relay 348 in addition to completing a locking circuit for itself at armature 353 as previously described, also completes at this same armature a circuit for relay 332. This latter relay upon opcrating, at its armatures 331 and 334, disconmeets the regular trunk line conductors and 325 and substitutes therefore the toll conductors, at its armature 333 disconnects ground from the holding circuit of ring cut-off relay 335 of the connector H and relay 108 of the relay equipment B, and at this same armature completes a new locking circuit for relay 326. Relay 108 deenergizes and at its armature 109 completes a new holding circuit for relay 335 before this relay has had time to deenergize. This circuit may be traced from armature 116 of the relay 114 a'nd its resting con-tact, resting contact of armature122 and the said armature conductor 119, resting contact of armature 109 and the said armature,conductor 151, working contact of armature 154 and the said armature, conductor 140, wiper 172, bank contact 176, conductor 168, armature 337 and its working contact, and the lower winding of ring cut-01f relay 335 to battery. Relay 108, also, at its armatures 107 and 106, again connects the winding of supervisory relay 112 in bridge of the conductors 104 and 105, and at itsarmature 110 completes a circuit for reversing relay 128. Relay 128 upon operating, at its armatures 127 and 129, reverses the direction of current flow as regards conductors 81 and 83, for a purpose which will be subsequently made clear, and at its armature 126 connects the alternating current relay 130 in bridge of conductors 81 and 83.

This time when the operator restores key K to normal, the current flow in the conductors 56 and 57 having been reversed by the energization of reversing relay 128, the polarized relay, 20 operates in the proper direction to complete the circuit of lamp 19. The glowing of lamp 19 indicates to the operator that the called line is idle, and that she may initiate the automatic ringing at any time. In order to do this the operator momentarily throws her key K in the proper direction to transmit a ringing current impulse out over the conductors 56 and 57, which now extend by way of conductois 81 and 83 to the alternating current relay 130 which was bridged across these latter conductors when the reversing relay 128 operated. Relay 130 now operates and, at its armature 131, completes a circuit for slow nevegsse release relay 1.14. Upon operating, relay #lil42at its:armature 116 temporarily l'GHlOVBS ground from the previously described holding'circuit ot'fthe vrelay This latter relay @deenergizcs and at its armatures 336 and 338 connects interruptergenerator and ground to the conductors 862and 368 which have been extended into connection with the line ol substation A. cansing'the si nallin device :thereat to be operated. l Vhen the called subscriber responds, the current flow through the upper winding of the cut-cit :rclay 335, which was included in 'thiv cirouit, is increased suliioiently to cause this arelay to operate and at its arn'iaturcs 336 and SSSanththeirWorking contacts complete the talking-circuit, and at its armature 337 locksitselt up-over the previously described locking circuit, the relay 3'14being again deenergized by this time. An operating circuit is now completed for the supervisory relay 112 inthe relayequi innent B ot thetoll transmission selector E. This circuit may betraced from grounded resting-contact o-t armature 106 and the said armature resistance 101, lower right hand winding of the repeating coil R, conductor 105, resting contact of armature 117 and the said armature, conductor 133, armature 157 and its working-contact, wiper 174, banl: contact 178, conductor 1-70,ar1nature 334 and its working contact, working contactof armature 338 and the said armature, armature 354 andits working contact, wiper 358, bank contact 368, conductor 372, (Fig. 4), springs --j. 28 and 4.26 whichinclude the usual protectiveapparatus (not shown) to the signalling apparatus at station A and back through the springs 422 and 424 of the protective apparatus, conductor -870, bank contact .366, wiper 356, working contactot armature 349 and the said armature, conductor 362, an inature 336 vand its working contact, worltingcontact of armature 331 and the said ar- ;n1ature, conductor 167, bank contact 175, wiper 17 1, working contact of armature 153 and the said armature, working contact of arn'lature 139 and said armature, conductor T132, armature 118 and its resting contact,

upper right hand winding of the repeating coil Ti, resistance "100, armature 107 and its resting contact, and the windingo-f'the relay 112 to battery. ielay 112 upon operating, at its armature 113, completes a circuit "for relay 120. This relay in turn operates and at'its armatures 123 and 1215 disconnects the line relay 141 from connection with the conductors 81 and 83, at its armature 123 completes a local holding circuit "for main taining'relay 141-energized and at its armature 122 switches the conductor 119 into connection with its grounded contact, which is independent of the control of slow relay 114, so that the operator cannot again unlock the ring cnt-oti" relay, while the called subscriber has responded.

:subscriberrhas his receiver oif:the'heok,:by

operating 1 her ringing key. The removal of the :line rela-y "fOLHlTIH bridge of conductors Stand 83 causes .the polarized relay :20 ".to

dcenergize, thereby extinguishing lamp :19

that th'ecalling subscriber 'is waiting on the line, restores .key K to normal :and permits conversation to proceed.

It for any reason the operator wishes to recall the subscriber at 14!, either when the receiver has been replaced or when the called subscriber'has merely left the telephone with the receiver of]? the hook, she may tlo so by 'againoperating her key K as before.

In case the subscriber replaces his receiver on the switch hook the relays 1 12 and 120 deenergi-Ze, and when the operator operates hey K the automatic ringin g operation is initiated andcut oflin the manner previouslydescribed.

It the called subscriber has left the ireceiver'oii the hook,.-relays 1:12 and 120wwill bcenergized when the operator throws her key K. This time when relay 1114 operates it completes a local holdingcircuit for relay 112 atconta'cts controlled by armature 118 so that relays 1 12and 12O re1nain-energized. Since the ring ent-oft re'l-ay 335 is locked up-over the grounded workingeontact oi armature 122-of relay 120 it willnot be deenergized at this time, but instead direct generator and ground are connected to the called line by way ot'arma'turesl121'and 124 ot'relay 120. This generator i's-applied only during the time the relay 114 is operated.

At the termination-ot the conversatiointhe calllng and called subscribers replace their receivers upontheir respective switchhooks.

T he replacement of the receiver at -the calling station causes 'tlre usual disconnect supersupervisory lamp 12 to be lighted. The 'replacement of the receiver at the called-stationcauses a supervisory relay 112 (Fig. 2 to deenergizeto in turn cause the relay to deenergize to again connect the line relay 141 in bridge of conductors 81 and 82. Since the reversingrelay 128 is still energized, the

polarized relay 20in the cord circuit will now be operated in the proper direction to cause the disconnectlamp 19 to be lli'ght'ed. Theoperator upon noting that :both discon 'nect lamps 12 211161 19 are liglited knows that the conversation has been completed and proceeds to pull down the connection. \Vhen the plug is removed from the answering end of the cord, the circuits of relays 2, 11 and 14 are broken and these relays are restored to normal. hen the plug is removed from the calling end,'the circuit for line relay 141 of the selector E is interrupted to bring about the release of the switches D, E and H, in the same manner as described when the called line was busy.

Interception of calls from (lead levels in. the toll selector.

Before proceeding with the description, Fig. 7 of the drawings should be placed at the left of Fig. 1, with the corresponding lines in alignment. Fig. 6 should also be placed at the left of Fig. 7. It may be well to explain at this time that in order to avoid the necessity of showing the individual line switch, such as C associated with each of the relay groups KG, RG etc., the drawings have been so arranged that during the process of describing the operation of these various relay' groups the drawing showing switch C may be shifted from one relay group to another.

It will now be assumed that the first digit of the number given the operator is incorrect. It will be assumed further that the first digit of the number given the operator corresponds to a dead level in the bank of the selector D. The operator not knowing this, however, proceeds to set up the connection in the usual manner. The bank contacts AU-49, inclusive, represent the bank contacts of a dead level in the selector D, and it will be assumed that this is the particular level selected by the operator. As soon as the selector D takes its first rotary step, in the same manner as previously described, the test wiper 42 engages the first bank contact 48 of the selected level.

In cases where there are very few calls trunked to dead levels, only one relaygroup, such as the group HG, need be provided, this relay group being multipled to all sets of contacts in the dead level. If, however. the tratfic to these dead levels is such that one relay group is insufilcient, the contacts in the dead level may be split up into two or more groups, each group then being provided with relay equipment, such as HG.

Returning now to the operation of the se lector D. it will be assumed that the level selected has its contacts divided into more than one group, and that the first group engaged is busy. The test contact 4-8 will be grounded as well as other test contacts common to the same relay group RG, and the selector D will operate in the manner pre viously described until a test contact 48 associated with an idle relay group RG is ground, at which time no ground potential will be present on the test contact 48 and the selector D will switch through in the manner previously described. The switching relay 54 upon operating extends the trunk conductors 56 and 57 to conductors 16 and 18, which latter conductors are provided with branches extending by way 01" armatures 77 and 79 and their resting contacts to the winding of relay 64; to ground and battery, respectively. Another circuit extends by way of grounded release trunk conductor 24:, working contact and armature 40 of relay to the conductor 17, which has connections extending by way of ar1nature and its resting contact, and resting contact and armature 69 and the said armature to the windings of relays 61 and 62, respectively. Relays 6%, ('31 and 62 operate over the above traced circuits. Relay G 1 upon operating, at its armature 76, completes a circuit for slow release relay 66. This latter relay in turn operates and at its armature S i applies ground to the conductor 17 to maintain the switching relay 51 and relays 61 and 62 operated after the slow relay 28 deenergizes, and at its armature applies ground to the conductor 74-2. Relay 61 upon operating, at its armature 7 3, prepares a point in the operating circuit of uelay 60, and at its armature 7 1 closes a point in the locking circuit of relay 62. llelay (52 upon operating, at its armature l0, completes a locking circuit for itself. and at its armatures 72 and 71 disconnects conductors 743 and 741 from upper winding of relay 62 and ground, respectively, and connects these conductors to conductors 16 and 18. The ground applied to conductor 742 by the operation of relay 66 extends by way of conductor 742 through the pull down winding 745 of line switch 0 springs 738 and 739, conductor 748, armature 732' and its resting contact to battery. The line switch C operates and by the operation of its armature 7&8 causes the holding winding and battery to be switched in series with the pull up winding 745, thereby maintaining the switch C operated independent of the battery fo'rn'ieiy supplied through armature 733. The operation of the line switch C also causes the bank contact springs 718, 720 and 722 to engage their associated springs 71?, 719 and 79.1. Springs 719 and 720 upon closing complete a circuit extending to the master switch bank contact upon which the master switch wiper 71.3 is now resting, energizii'ig the starting relay 78-12 of the master switch MS. Upon energizing, the relay 7 8st closes a circuit for the locking magnet 7 32, which unlocks the masterswitch shaft and thus brings about the re-alignment of all id'e line switch plungers before bank springs in which is terminated the next idle trunk line. he starting relay 734i a so closes circuit for the open main relay 731, which, upon energizing, disconnects the common conductor 748 from the negative pole of the battery in order to prevent any of the line switches from being operated until the master switch comes to rest. The closure of springs 717 and 718, and 721 and 72 causes the conductors 74.1 and 743 to be extended to the trunk lin'e conductors 708 and 709 which terminate in the jack J at an intercepting operators position in the centraliy located office.

The operator, not knowing that she has set the wipers of the selector on a dead level, will continue to operate her calling device in accordance with the remaining digits of the called number. Since the selector D has cut through and extended the conductors 57 and 56 into connection with the conductors 16 and 18, across which is bridged the relay 6%, the remaining series of impulses will merely cause this relay to vibrate. Relay 66, however, being of the slow acting type, remains operated during this time. The operator having completed the dialling of the called number, restores the key K to normal, substituting therefor the polarized relay 20 in the manner previously described. It will be notedthat the battery and ground connections of the relay 6% are such that the current flow over conductors 56 and 57 is the same as had the connection been completed to an ide called line and therefore polarized relay 20 operates, causing the lamp 19 to glow to indicate to the operator that the called line is idle and that she may initiate the automatic ringing at any time. This time when the operator causes a ringing current impulse to be transmitted out over conductors 57 and 56, which are now connected to conductors 16 and 18, the alternating current relay 63, which isalso in bridge of conductors 16 and 18' in multiple with relay 6%, is operated, and at its armature opens t1 locking circuits of relays 61 and 62. These relays, accordingly,.deenergize. Due to the slow acting feature of relay 61 the deenergization ofthis relay is slightly delayed and therefore when armature 75 of relay 6st engages its working contact, a circuit is completed for relay 60. Relay 60 upon operating, at its armature 68, locks itself up over a circuit independentof relays 61 and 63 and at its armature 67 applies interrupted generator to the upper winding of cut-off relay 62. Since the relay 62 is now at normal, ringing current is transmitted to the ring up relay 714 at the intercepting operators position. This circuit may be traced from interrupted generator. working contact of armature 67 and the said armature, upper winding of cut-off relay 62, resting contact of armature 71 and the said armature, conductor 7413, bank springs 722 and 721, conductor 709, condenser 72-1, lower winding of relay 714 armature 7 and its resting contact, conduc tor 708, bank springs 717 and 718, conductor 741, and armature 72 and its resting contact to ground. Ring up relay 71 1 operates over the above traced circuit and completes a locking circuit for itself at armature 716, and at its armature 715 completes a circuit for the call signal lamp 700. The intercepting operator, upon noting the lighted condition of lamp 700, responds by inserting the plug P of the 'cord circuit 0 into the answering jack J'". A circuit is now completed for relay 630. This circuit extends from battery, winding of the said relay, springs controlled by armature 631, resting contct of armature 628 and the said armature, conductor 613, ring terminal of the plug P ring side of the jack J and springs controlled by armature 711 to ground. Upon operating, relay 630 at its armature 631 disconnects direct ground from, the winding of relay 630 and substitutes therefor the sleeve relay 710 and ground. Relay 710 operates and opens the energizing and locking circuits of relay 714-. Relay 630 at its armature 629 also completes a circuit for slow relay 624., which operates to in turn complete the circuit of slow relay 626. Before the relay 626 has had time to actuate its armature a ground impulse is transmitted out over conductor 613 by way of ground supplied by the actuated armature 632. This ground impulse is of short duration, but is of suflicient duration to cause the operation of ring cut-off relay 62. Relay 62 upon operating, at its armature 70, completes a locking circuit for itself and at its arinatures 71 and 72 disconnects conductors and 741 from generator and ground and connects these conductors to conductors 18 and 16, respectively. Relay 626 upon operating, at its armature 628 and its working contact, closes a bridge across conductors 612 and 613, which includes the impedance coil 60st and high resistance polarized relay 610 in series. Conductors 612 and 613 now extend to conductors 741 and 743 across which are bridged the windings of relay 65. The resistance of relay 610 is very high compared with that of relay 65, and this latter relay therefore does not energize at this time. The polarized relay 610 is poled to swing its ai i'nature to the left when the call being intercepted is from a toll switch, battery being applied over the ring conductor,- and therefore in this instance operates and completes a circuit for relay 622. Relay 622 upon operating at its armature 621, completes a holding circuit for itself, and at its armature 623 short circuits the winding of polarized relay 610, whichaccordingly restores its armature to normal. As soon as relay 610 is short circuited, the current relay to energize. Relay 65 upon operating, at its armature 78, applies ground to relay 66 independent of armature 76, and at its armatures 7? and 79 disconnects the relays 63 and 64 from in bridge of conductors 16 and 18. As a result the polarized relay .20 in the cord circuit 0 deei'iergizes, causing the lamp 19 to be extinguished, thereby indicating to the toll operator that the call has been answered. The intercepting and toll operators, after throwing their keys K and K, respectively may now converse. lVhen the intercepting operator has given the toll operator the necessary information regarding the desired called number, she pulis down the connection. The withdrawal of the plug? from the jack J breaks the circuits of relays 630 and 710. The relay 630, upon deenergizing, bringsabout the restoration of relays 622, 624- and 626. Relay 710, upon deenergizing, again completes the normal connections of relay 714. All apparatus at the intercepting operators position is now at normal. The withdr wal of the plug P also causes the deenergization of relay 65 of the relay group RG. This relay, upon deenergizing, again connects the relay 64 in bridge of conductors 16 and 18. The connection of relay 64 in the above bridge causes the polarized relay 20 in the cord circuit 0 to again operate causing the lamp 19 to glow to inform the toll operator that the intercepting operator has disconnected her cord from the trunk. The toll operator, accordingly, withdraws the plug P from jack J, thereby opening the operating bridge of relay 64. Relay 64 upon retracting its armature opens the circuit of relay 66, which in turn tie-energizes, removing ground from the holding circuit of switching relay 54. Relay 54 upon retracting its armatures completes the previously described circuit for restoring the selector D to normal. The deenergization of relay 66 also causes ground to be removed from conductor 742 to permit the line switch C to also restore to normal.

Interception of calls from dead Zeoels in toll transmission selectors.

It will now be assumed that the second digit of the called number given to the toll operator is incorrect instead of the first digit. It will be further assumed that this second digit corresponds to the dead level comprising bank contacts 179, 180, 181, and 182 of the selector E. When the selector E is operated to position its wipers opposite the desired level, the automatic rotary movement is initiated in the same manner as previously described. Since trunk selecting operations by the selector D as well as of the selector E have been previously explained, it will be assumed that the first relay group RG of the dead group terminating in contacts 179, 180, 181, and 182 is idle. The switching relay 152 therefore energizes, at its armature 155 opening the vertical magnet operating circuit, at its armature 156 connecting ground to wiper 173 to make this trunk line busy to other selectors, and at armature 154 removes ground from the holding circuit of relay 108, which relay now deenergizes. Relay 108, upon deenergizing, at its armature 109 closes a point in a holding circuit for relay 184 and at its armature 110 closes the previously described operating circuit of reversing relay 128. Relay 152 also at its armatures 153 and 154 extends the trunk conductors 32 and 133 to the conductors 192 and 195. The ground applied to the test wiper 173, by the operation of the switching relay 152, causes the energization of cut-olf relay 184. Relay 184 upon operating, at its armature 186, completes a circuit for relay 185, at its armature 187 closes a point in a locking circuit for itself, and at its armatures 183 and 188 extends conductors 192 and 195 into connection with conductors 741 and 743. Relay 185 upon operating, at its armature 189, completes a locking circuit for itself independent of relay 184, at its armature 191 completes a locking circuit for relay 184, at its armature 190 opens the original energizing circuit of relay 184, and at its armature 192 connects interrupted generator to the upper winding of relay 184. it should be noted that the grounding of con ductor 742, by the'operation of switching relay 152 also caused the switch C to be operated in the same manner as previously described when the call was intercepted from a first selector level. The remaining series of impulses transmitted by the toll operator will now cause the line relay 141 of the selector E to vibrate as previously described. This operation, however, will be without efiect since the operating circuit is openedat armature 155 of the switching relay. The operator having completed her dialling operation now restores key K to normal, substituting the polarized relay 20 as before. Reversing relay 128 being now energized, the current flow is in the proper direction to operate the polarized relay, causing the lamp 19 to glow to indicate to the toll operator that the called line is idle, and that she may initiate the automatic ringing at any time. The relay 128 being in operated position, alternating current relay 130 is again in bridge of conductors 81 and 83 and therefore responds as before to ener gize slow relay 114, and relay 114 upon operating, at its armature 116, removes ground from the conductor 151 which now extends by way of wiper 172 to the holding winding of cut-off relay 184 causing this relay to deenergize. Relay 184 upon rc tracting its ari'natures 183 and 138 new con nects interrupter generator and ground, respectively, to conductors 741 and 7 43. This interrupted generator causes ring up relay 714 to operate in the manner previously described. lVhen the intercepting opelrator answers the call, the ring cut-oil relay 184 operates in the same manner as did the ring cut-oil relay 62 of relay group RG (Fig. 1). Relay 184 upon operating, at its armature 187 again locks up over the previously describet circuit, relay 114 having deenergized by this time, at its armatures 183 and 188 disconnects conductors 741 and 743 from generator and ground, respectively, and connects these conductors to conductors 192 and 195, respectively. Battery and ground is now supplied by supervisory relay 112 and by the back contact of relay 108, (relay group B) causing the polarized relay 610 in the intercepting operators cord circuit to be operated, relay 112 not being operated due to the high resistance of relay (510. Relay 610 upon operating, causes the operation of relay 622, which latter relay short circuits the polarized relay causing the current iiow to be increased suliiciently to permit the operation of supervisory relay 112. Relay 112 upon operating causes the energization of relay 120, which, in the manner previously described, removes battery and ground from conductors 81 and 83, causing the deenergization of the polarized relay 20, resulting in the lamp 19 being e tinguished to notify the operator that the called party has responded. 'Conversation may now take place. As soon as the conversation between the intercepting operator and the toll operator has been terminated, the intercepting operator upon withdrawing the plug of the cord from the associated jack thereby opens the bridge for maintaining supervisory relay 112 ot the relay group B operated. This relay accordingly deener gizes, again bridging the line relay 141 across conductors 81 and 83. The polarized relay 20 now operates causing lamp 19 to glow to notify the toll operator that the intercepting operator has withdrawn the plug of her cord from the trunk line, The toll operator upon withdrawing the plug? from the jack J causes the selectors l) and E to restore in the usual manner. soon as relay 152 of the selector E decnergizes, ground is removed from wiper 173, causing the holding circuit of relays 184, 185, and line switch C to be broken, accordingly, these relays, and line switch also restore to normal.

of calls from line zfcivninals in connector banks.

it will now be assumed that all digits of the'called number as given the toll operator are correct, but that the desired SL1l)SCI1lJ1"S line is out of order. It will further be. assumed that in preference to having this subscribers line entirely out of service that the attendant in the local oflice has separated the conductors nori'nally extending to the line terminals of the connector bank from the subscribers line and has retrunked them by way of the cord 0 to the relay group RG and to conductors 433 and terminating in answering equipment at a place readily observed by the attendant. Responsive to the final digit of the called number, the connector is positioned on the terminals of the desired line, and assuming that this line is idle at this time, switches through in the manner previously described. The operator therefor operates her ringing key, to transmit an alternating current impulse to initiate the automatic ringing as before. This ringing current flows .out over conductor 370 by way of conductor 402 of the cord conductor 431,-resting contact of armature 860, condenser 833, and the winding of relay 864 to ground. Relay 864 upon operating, at its armature 865 completes a locking circuit vfor itself and at its armature 866 applies ground to conductor 742 The grounding of conductor 742 causes the line switch C to operate and seize an idle trunk in the same manner as previously described. Since nothing has happened to cut off the ringing current supplied by the connector, this ringing current is now transmitted by way of conductor 743 bank contactsprings of the line switch C conductor 709, ring up relay 714 and back over conductors 708, 741, 741 432, 403, 372 and 363 to ground, causing relay 714 to operate in the manner previously described. The response of the intercepting operator causes ring cut-off relay 335-of the connector H to operate and lock up in the same manner previously de scribed, with reference to cut-oil relay 62, at the same time transferring the conductors 362 and 363 from connection with ringing generator and ground into connection with conductors 167 and 170, which now extend back over the previously traced circuit to conductors 104 and 105, across which is bridged the supervisory relay'112. Current supplied by supervisory relay 112 is sulficient to cause the operation or polarized relay 610 of the intercepting operators cord, and relay 850 in the relay group PG? Relay 850 upon operating, at its armature 851 completes a circuit for relay 856. This latter relay, upon operating, at its armatures 857 and 860, disconnects relays 861 and 864 from in bridge of conductors 431 and 432, at its armature 858 removes ground from the locking winding of relay 864 causing this relay to deenergize, and at its armature 859 applies ground to conductor "42 in substitution of the ground formerly supplied by relay 864. Relay G10 upon operat-

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