US1778204A - Telephone system - Google Patents

Description

Oct. 14, 1930. J. WICKS TELEPHONE S YSTEM Filed Aug. 6', 1928 6 Sheets-Sheet 1 Oct. 14, 1930. J. WICKS TELEPHONE SYSTEM 6 Sheets-Sheet 2 Filed Aug. 6, 1928 Ma g 3 Jo hm Wicks Oct. 14, 1930. J. wlcKs TELEPHONE SYSTEM Filed Aug. 6, 1928 s Sheet-Sheet s b NMMQ Inuen or v John Micki Oct. 14, 1930. .1. WlCKS TELEPHONE SYSTEM Filed Aug. 6, 1.928 6 Sheets-Sheet 4 Nvm Oct. 14, 1930. J. WICKS TELEPHONE SYSTEM Filed Aug. 6, 1928 6 Sheets-Sheet 5 Elm Im.ren 1:1 Ja Zm wicks I m wwm PRF P Oct. 14, 1930. J. WICKS TELEPHONE SYSTEM Filed Aug. 6, 1928 6 Sheets-Sheet 6 wmxi fi -33 John Nicks Patented @ct. 14, 1932 U ITED STATES PATENT OFFIOE.

JOHN WIGKS, OF OAK PARK, ILLINOIS, ASSIGNOR TO RESERVE HOLDING COMPANY, OF KANSAS CITY, MISSOURI, A CORPORATION OF DELAWARE TELEPHONE SYSTEM Application filed August 6, 1928. Serial No. 297,611.

The present invention relates to telephone systems in general, but as regards a number of its objects and features, it is concerned more particularly with automatic telephone systems of the so-called inverted type in which talking battery and holding potentials are supplied from a first selector rather than a connector. This case may be considered as with the present inverted system and to enable a toll operator to cut inon local connections in case either one of the local subscribers is desired in a toll connection and break down such local connection in order to complete the desired toll connection. In case the desired local subscriber is engaged in a toll connection, the toll operator will be automatically notified of this fact by means of a toll busy tone and she will be unable to out in and break down such a toll connection.

Another object of the invention is to provide improved metering and zone metering circuit arrangements for metering the call after the termination of conversation. Metering on calls is to take place after the termination of conversation instead of when the called party answers because the completed connection is liable at any time to be interrupted by a toll operator coming in on the connection to establish a desired toll connection. Another object of the invention is to pro vide new and improved selectors and selector repeater circuits such that the selectors hunt .for a battery potential on their associated According to another feature, a new and improved rotary connector accessible for use in both local and toll connections has been provided to take care of the situation in which a calling subscriber may call a common call number and connect with the first idle one of several lines having such a common call number. Circuit arran ements are also provided in this improve connector whereby a calling subscriber can call and conncct with a particular one of these subscribers having a common call number.

There are, of course, a number of objects and features subsidiary to the foregoing which may be understood best from a further perusal of this specification.

Referring now to the accompanying drawings comprising Figs. 1 to 7, inclusive, Figs. 1 to 6 show by means of the usual circuit diagrams a sufficient amount of equipment.employed in a telephone system embodying the principles of the invention to enable the invention to be understood. Fig. 7 is a diagram showing how the sheets of drawings, on which Figs. 1 to 6 appear, should be arranged in order to be understood best.

F ig. 1 shows a two conductor toll service trunk extending from the jack J at the toll board to the toll transmission selector repeater located at the local automatic exchange. Fig. 1 also shows the cord circuit CC which is one of the cord circuits used by the toll operator to complete connections to the toll service trunk through the jacks such as J. Other trunk lines, such as the trunk line comprising conductors 9 and 10 (extend from the toll board to other automatic otlices in this telephone system.

Fig. 2 shows the transmission selector repeater on the incoming end of the interofiice trunk line comprising conductors 9 and 10 extending from jack J, Fig. 1. This transmission selector repeater is of a special design so as to give the operator the correct supervision and so as to enable the operator to control the starting of the application of ringing current to the called line. This selector repeater is also designed so as to enable the operator to cut in on a local established connection and break down such connection in order to complete a toll connection to the desired called subscriber. A transmis- .sion selector repeater of the same design is cess to intermediate selectors such asthe selectors shown in Fig. 4.

Fig. 3 shows the first selector re eater which is accessibleto the line switch L associated with the line of substation A. This selector repeater is provided'with the necessary arrangements forfeeding talking battery to the calling subscriber in all cases and to the called subscriber on local calls. It is also provided withthe necessary arran ements for preventingv the operation of t e subscribers meter when the operator breaks down a local established connection. Circuit arrangements are also provided in the first selector repeater for holding the line switch operated after the callin subscriber has replaced his receiver in order to meter the call upon release. The circuits are also arranged so that the calling subscriber, in making a new call, will not interfere with the metering operation until the metering operation has been completed.

Fig. 4 shows two intermediate selectors, the first of which is shown in detail and is accessible to the first selector repeater shown in Fig. 3. The second intermediate selector which is similar in all respects to the first intermediate selector is accessible from the first intermediate selector and the transmission selector repeater, Fig. 2, located inthe local automatic exchange.

Figure 5 shows a rotary connector which is accessible to the second intermediate selector shown in Fig. 4 and is used for calling individual lines and also for calling lines associated in groups with the number of the first line assigned as the call number of the entire group. This rotary connector is also provided with circuit arrangements such that a subscriber may call a particular line out of a group of lines having the same directory call number. This connector is provided with circuit arrangements so as to provide a guarding potential of one character in case a local connection has been established or if the connector has been used to complete a toll connection to provide a discriminating guarding potential on the test contact of the called line. This connector is also provided with means for cutting in on a local connection and breaking down such local connection.

- The rotary connector has access to subscribers lines such as A and A. The line switch LS is similar to the line switch LS in Fig. 3 and is individual to the line of subscriber A. i

Fig. 5A shows in detail the mannerin.

which the test contacts accessible to. test wiper 464 of the rotary connector are ar-' ranged in order to permit the rotary connector to seize an idle line in a grou of lines in case .the group number is calle and to connect wit group, such as illustrated b contacts 482, in case the corresponding num er of such intermediate line is called. As illustrated in Fig. 5A, 480 is the test contact accessible to'wiper 464 of the first line of a group of lines, while test contacts 482 are intermediate lines and test contact 483 is the test contact of the last line in that particular group. Contact 485 is another first test contact in another group .while contact 486 is the last test contact of such other group. Each first contact-in the group has batter potential permanently oonnected thereto y we of the resistances such as 481 and 481 wh1le the last test contacts in the-group have ground permanently connected thereto. The test contacts of individual lines, such as 484, and intermediate lines of a grou such as 482, are left dead.

To the left-oi t is shown the trunk meter relays associated with the trunk comprising conductors 601 and 602 extendin The trunk meter relays are individual to the trunk and are taken into use when the first selector repeater is operated to seize the trunk line extending to the distant automatic exchange. The function of the trunk meter relays are to maintain the first selector'repeater, Fig. 3, in operated position, until the proper number of meterin impulses have can sent 'for operating t e calling subscribers meter. To the right of the dotted line in Fig. 6 there is shown an incoming selector repeater located in the distant automatic exchange. The incoming selector repeater is accessible to first selector repeaters m the local automatic exchange by way of the trunk line comprising conductors 601 and 602. The incoming selector repeater is provided with means for repeating impulses to succeeding switches in the distant automatic exchange and for providing a holding circuit for the same; for operating an answering brid e in the first selector repeater when the call is answered; for breaking down a local connection in case an operator desires to complete a toll connection to the called subscriber; for preventing the operation of the calling subscribers meter when the connection has been broken down; and for supplying talking battery to the called subscriber. The incoming selector repeater has access to intermediate selectors such as is shown in Fig. 4 and such intermediate selectors have access to connector switches such as shown in Fig. 5, all of which are located in the distant automatic exchange. The connectors have access to the subscribers lines terminating in the distant automatic exchange. 1

Regarding the mechanical construction he dotted line in Fig. 6 there from the local automatic. exchange to the lstant automatic exchange.

any intermediate line of a of the apparatus shown, the various selectors, selector repeaters and connectors are mechanically of the well known vertical and rotary type of switch in which the bank con- 'tacts are arranged in horizontal rows or levels.

The various selector repeaters and intermediate selectors are of the tye commonly referred to as the battery hunting ty l The various line switches, such as L and LS, are mechanically of the well known rotary type of switch in which the wipers are advanced in one direction only and are advanced upon the back stroke of their associated stepping magnets.

The invention having been described generally, a detailed description of the operation of the apparatus shown will now be given. For this purpose, it will be assumed that the subscriber at substation A, desiring to converse with the subscriber at substation A, removes his receiver and dials the digits in the telephone number of the subscriber at the substation A.

Calls from substation A to substation A When the receiver is removed at substation A, a circuit is closed over line conductors 201 and 202 for line relay 204 of the line switch LS. Line relay 204 energizes over the calling line and places ground on the associated private normal conductor 218 leading to the banks of the connector switches having access to the line of substation A thereby making this line busy to those connectors, and also closes a circuit through the combined switching and cut-ofi' relay 203 and the motor magnet 205. Line relay 204 also at armature 220 connects test wiper 211 through armature 207 and its resting contact to the junction of relay 203 and magnet 205. Accordingly, if the trunk upon which the wipers of the switch are standing is busy the ground potential encountered by test wiper 211 shunts the relay 203 and prevents it from energizing and affords a direct circuit for the self-interrupting stepping magnet 205. Accordingly, stepping magnet 205 operates in a buzzer-like manner to advance the wipers 210 to 213, inclusive, in search of an idle trunk line.

When an idle trunk line is reached, stepping magnet 205 ceases to operate, and relay 203, being no longer short circuited, energizes in series with stepping magnet 205, which however, does not operate at this time on account of the relatively high resistance of relay 203. Upon energizing, relay 203 disconnects test wiper 211 from thejunction of its own winding and that of magnet 205 and connects it to the grounded private normal conductor 218, thereby extending ground through the release trunk conductor 215 of the seized trunk; connects up the meter operating wiper 212 at armature 208; and at armatures 206 and 209 disconnects conductors 201 and 202 from line relay 204 and ground and extends them by way of wipers 210 and 213, conductors 214 and 217, armatures 273 and 279 and their resting contacts, and through the upper and lower windings of line relay 221 and relay 224 to battery and ground. Line relay 221 energizes over the above traced circuit but relay 224 being differential and stifliy adjusted will operate only when ground is connected to both its windings. Line relay 221, upon energizing, at armature 240 closes a circuit for energizing relays 223 and 227 in series; and at armature 241 removes the short circuit from around release relay 222 and closes an energizing circuit for release relay 222 in series with the vertical magnet 230 and the upper and lower windings of relay 226. Release relay 222 energizes over the above traced circuit but relay 226 and vertical magnet 230 do not operate because of the high resistance of release relay 222. Release relay 222, upon energizing, at armature 242 closes a shunt around the armature 261; at armature 244prepares a point in the holding circuit of relay223; at armature 244 opens a point in the circuit to the release magnet 232; at armature 245 grounds the release trunk 215 thereby maintaining the line switch LS in operated position when ground is removed from armature 219 by the deenergization of line relay 204; at armature 246 grounds conductor 233; and at armature 247 completes a locking circuit for itself as well as preparing the impulsing circuit through the vertical magnet. 223 and 227 may be traced as follows: from The circuit for energizing relays ground by way of the upper winding of relay 227, normally closed springs controlled by its working contact, upper winding of relay 223 and upper winding of relay 224 to battery. Due to its spring adjustments relay 224 is not energized over this circuit. Relay 223, upon energizing, at armature 249 opens a point in the circuit of the release magnet as well as opening a. point in the circuit for operating the calling subscribers meter and at armature 250 prepares an energizing circuit for relay 225 which, however, is opened at armature 270 at this time. Relay 227, upon energizing, at armature 266 connects up ground through resistance 267 in order to maintain relay 223 energized during impulsing; at armature 268 and its working contact connects the dial tone to conductor 214; at armature 269 removes the shunt circuit from around the upper winding of relay 228; at armature 270 and its resting contact opens a point in the circuit of relay 225 and at its working contact completes a locking circuit for itself, extending from ground by way of armature 250; and at armature 271 prepares a circuit for grounding wiper 292 while the first selector repeater is repeating impulses desired level of bank contacts.

to the succeeding switches in order to improve the impulsing circuit.

Dial toneextends by way of conductor 272, normally closed off-normal springs 265, working contact'of armature 268 and said armature, condenser 274, resting contact of armature 273 and said armature; conductor 214,

wiper 210, working contact of armature 206 and said armature, conductor 201, over the calling loop, through conductor 202, armature 209 and its working contact, wiper 213,

. conductor 217, armature 279 and its resting ture 241, armature 283 and its resting contact, and through the winding of vertical magnet 230 to battery. By the operation of i the vertical magnet 230 the switch wipers 290 to 292, inclusive, are operated opposite the A branch of this impulsing circuit extends through the lower and upper windings of relay 226 to battery, causing such relay to energize. Relay 221 at armature 241, in addition to closing the impulsing circuit, also closes a short circuit around release relay 222 in order to render the release rela slow to release so that it will be maintaine in operated position during the impulsing period. At armature 240 line relay 221 closes a circuit extending by way of ground through resistance 267, working contact of armature 266, armature 257 armature 243, make-before-break springs controlled by armature 240, upper winding of relay 223, and upper winding of relay 224 to battery for maintaining relay 223 energized the impulsing period.

Relay 226, upon energizing, at armature 261 opens the initial energizing circuit for line relay 221; at armature 262 opens up a point in the circuit for the rotary magnet 231 so that the rotary magnet will not operate when the ofl-normal springs 252 operate and close on the first vertical step of the switch; at armature 263 opens a point in the circuit for relay 225; and at armature 264 connects up ground in order to improve the imnulsing circuit to the succeeding switches. Relay 226 is slightly slow to fall back when its circuit is open during the impulsing period because of the current flow through relay 222. However, after impulsing, relay 226 falls back after a certain period of time. At armature 262 relay 226 closes a circuit for operating the rotary magnet 231 as follows from ground on release trunk conductor 215, armature 255, armature 278, armature 262 and itsresting contact, armature 251, off-normal spri: gs 252, resting contact of armature 281 and said armature, interrupter springs-288 of rotary magnet, and winding of rotary magnet 231 to battery. By the operation of the rotary magnet 231, the switch wipers 290 to 292, inclusive, are rotated into engagement with the first set of bank contacts in the selected level. Near the end of its stroke, rotary magnet 231 operates its interrupter springs 288, thereby interrupting its own circuit and the operation of the rotary magnet continues in a buzzerlike manner to ste the wipers over the'bank contacts in the se ected level until the test wiper 291 encounters a battery potential on one of the test contacts.

Assuming that the first idle trunk comprises the conductors 301 to 303, inclusive, extending to the intermediate selector shown in Fig. 4, then when wiper 291 encounters test contact 298 a circuit may. be traced for energizing switching relay 229 as follows: ground by way of grounded conductor 233, armature 269 and its working contact, up er winding of switching relay 229, Wiper 91, test contact 298, conductor 302, armature 310, normally closed springs controlled by armature 316, normally closed off-normal springs 312, and through resistance 345 to battery. From the foregoing, it will be seen that the rotary magnet rotates the switch Wipers until the test wiper 291 engages a test contact having batte potential thereon and therefore the first se ector repeater willnot stop on grounded test contacts or contacts upon which there are no potentials whatever. Relay 229, upon energizin at armatures 280 and 284 closes a circuit or energizing line relay 304 of the intermediate selector; at

armature 281 opens the rotary magnet circuit so as to stop the rotation of the switch and closes a locking circuit for itself extending by way of grounded release trunk conductor 215 through its lower winding and winding of-the rotary magnet in series to battery; at

armature 282 prepares a circuit for short cir-' cuiting the upper winding of switching relay 229 and connects groundpotential extending by way of grounded conductor 233 through the upper low resistance winding of relay 228 to conductor 302; and at armature 283 opens termediate selector may be tracedas follows: ground by way of lower winding of relay 224, lower winding of relay 223, normally closed springs controlled by armature 279, armature 284, wiper 292, contact 299, conductor 303, normally closed springs controlled by armature 323, winding of line relay 304, normally closed springs controlled by armature 319, conductor 301, bank contact 297, wiper 290, armature 280 and its working contact, normally closed strings controlled by armature 273, armature 240 and its working contact, upper. winding of relay 223, and upper winding of relay 224 to battery. Line relay 304 energizes over the above-traced circuit and relay 223 is maintained in operated position when its initial energizing circuit is opened at armature 280.

Line relay 304, upon energizing, at armature 310 opens the short circuit around the winding of relay 305, thereby permitting relay 305 to energize, and at armature 311 prepares the impulsing circuit for the vertical magnet. The circuit for energizing relay 305 may be traced as follows: from grounded conductor 302, by way of normally closed eleventh rotary step contacts 317, armature 320 and its resting contact, winding of relay 305, normally closed off-normal spring 312 and through resistance 345 to battery. Relay 305 immediately-energizes and at armature 314 opens the circuit to the rotary magnet; at armature 315 prepares the impulsing circuit to the vertical magnet and opens a point in the circuit to the release magnet 309; and at armature 316 prepares a new holding circuit for itself by shunting the normally closed off-normal springs 312 which will open on the first vertical step of the switch.

The calling subscriber may now dial the second digit in the called number and responsive thereto line relay 221 in the first selector repeater operates in the same man ner as previously described. Each time line relay 221 deenergizes. said relay at armature 240 opens the impulsing circuit extending to the line relay 304 in the intermediate selector. In addition, at armature 241 line relav 221 again completes the circuit for relay 226 so that the latter relay will energize and connect ground by way of armature 264 to conductor 303 so as to improve the impulsing circuit.

In the intermediate selector, line relay 304 responds to the interruptions in its circuit and at each deenergization operates the ver- 311, armature 315 and its working'contact,-

and winding of vertical magnet 307 to battery. On the first vertical operation of the switch the normally open elf-normal springs 312 close andprepare a circuit for shunting relay 305. During impulsing, however, relay 305 is intermittently energized and shunted by line relay 304 and therefore relay 305 is maintained in ener ized position during the impulsing period. Shortly after the transmission of impulses, relay 305 is shunted for a suificient time or time enough to permit such relay to be deenergized. The short circuit of relay 305 may be traced as follows: grounded conductor 302, normally closed springs 317, armature 320 and its resting contact, winding of rela 305 working contact of armature 316 an said armature, normally open springs 312 (now closed), armature 311 and its working contact, and resting contact of armature 322 and said armature to ground. Relay 305, upon deenergizing, at armature 314 closes a cirsuit for operating the rotary magnet 308;

cuit; and at armature 316 opens a point in the shunt circuit around itself. The circuit for energizing the rotary magnet 308 may be traced as follows: ground by way of armature 322, working contact of armature 311-and said armature, armature 314, interrupter springs 313 of the rotary magnet and through the winding of rotary magnet 308 to battery. Rotary magnet 308 energizes and interrupts its own circuit in a buzzer like manner to rotate the wipers in search of an idle trunk. Rotary magnet 308 continues to rotate the wipers over the bank contacts until an idle trunk is encountered, that is, until the wiper 327 encounters a contact having battery potential thereon.

Assuming that the second intermediate selector shown just to the right, is the first idle intermediate selector in this level, then there will be a battery potential on test contact 330 extending to a resistance, similar to resistance 345 in the first intermediate selector. When wiper 327 encounters the battery potential on test contact 330. switch ing relay 306 energizes over the following circuit: ground by way of grounded release trunk conductor 302, lower winding) of switching relay 306, test wiper 327, ank contact 330, release trunk conductor 333, and over a similar circuit to a resistance, similar to 345, and battery. Relay 306, upon energizing, at armature 320 disconnects relay 305 and connects the release trunk 302 straight through to release trunk 333 and also short circuits the lower energizing winding of switching relay 306; at armature 321 completes a locking circuit for itself through its upper winding to grounded release trunk conductor 302; p at armature 322 opens a point in the circuit for the release magnet 309; and at armatures 319 and 323 disconnects the line relay 304 and connects the talking conductors 301 and 303 to the talk- . ing conductors 332 and 334, respectively.

The deenergiza-tion of line relay 304 is without effect at this time other than to close a pognt in the circuit for the release magnet 30 The second intermediate selector seized over conductors 332 to 334, being similar in all respects to the intermediate selector just 1 described, will therefore operate in the same manner and seize an idle trunk, suclias the trunk comprising conductors 341 to 343, ex-

.tending to an idle connector responsive to the next series of impulses.

Assuming that the connector in Fig. 5is

the connector seized, the circuit for energizing the switching relay of the second intermediate selector may be traced as follows: ground by way of grounded release trunk conductor 333, winding of switchingrelay, test wiper 336, bank contact 339, conductor 342 armature 417 and its resting contact, normally closed ofi-normal springs 443. and

through the upper winding of relay 405 to battery and alsoby way of normally closed springs controlled byarmature 436, and resistance 442 to battery. Relay 405 in the connector does not operate until the switching relay in the second intermediate selector short circuits its upper winding, thereby permitting sufiicient current flow to energize relay 405.

When the second intermediate selector cuts through a circuit is completed for energizing line relay 402 of the connector as follows: from ground and battery through the upper and lower windings of relays 223 and 224 of the first selector repeater by way of the circuit previously traced over conductors 301 and 303, over conductors 332 and 334, con-' ductors 341 and 343, armatures 447 and 452 and their resting contacts, and through the at armatures 434 and 438 disconnects interrupted. generator and generator ground; at armature 435 prepares the impulsing circuit; at armature 436 disconnects the resistance 442 and completes a locking circuit for itself extending by way of grounded release trunk conductor 342; and at armature 437 opens a point in the circuit of the release magnet 412.

The calling subscriber may now dial the next digit of the called number and accordingly the line relay of the first selector interrupts the loop circuit extending to the line relay 402 of the connector. Each time the circuit of line relay 402 is opened said relay deenergizes and at armature 419 closes a circuit for operating the vertical magnet 410 as follows: ground by way of armature 435, normally closed springs controlled by armature 419, armature 448 and its resting contact armature 430, armature 416 and its resting contact and winding of vertical magnet 410 to battery. By the operation of the vertical magnet the switch wipers 463 to 466 are operated in the well known manner opposite the desired'level of bank contacts in' which the called. line terminates. During impulsing, a circuit mayv be traced for slow acting relay 406 as follows from ground by way of armature 435 by way of the previously traced impulsing circuit to armature 430,

and thence byway of armature 458 and its resting contact to the winding of relay 406 and battery. Slow acting relay 406, upon energizing, at armature 440 shunts'the contacts 430 of the busy relay 404; at armature 441 prepares a point in the circuit for the busy relay 404; at armature 444 shunts the busy relay contacts 432; and at armature 445 opens a point in the circuit of relays 401 and 409. Upon the first vertical step of the connector, off-normal springs 420 close and complete a circuit for energizing slow acting relay 408 when line relay 402'is in energized position as follows: ground by way of armature 435, working contact of armature 419 and said armature, off-normal springs 420, and winding of slow acting relay'408 to battery. Relay 408, upon energizing, at armature 455 prepares a point in the circuit for relay 407 at armature 456 prepares a cir cuit for grounding the lower talking conductor 343; and at'armature 457 prepares a circuit for energizing relay 401. At the offnormal springs414 a circuit for the release magnet is prepared and at off-normal springs 443 the original energizing circuit of relay 405 is opened. I

After receipt of thisoseries of impulses slow acting relay 406 deenergizes and at armature 445 completes a circuit for energizing relay 401 as follows: ground by way of armature 457, armature 445, armature 433 and its resting contact, and winding of relay 401 to battery. Relay 401, upon energizing, at armature 415 prepares a locking circuit for switching relay 407 at armature 416 opens the vertical magnet circuit and prepares the rotary magnet circuit; at armature 417 opens the locking circuit of relay 405 and closes a looking circuit for itself; and at armature 418 opens a point in the circuit of the release magnet 412 and connects ground by way of off-normal springs 414 to replace the ground which will shortly be removed at armature 435. The deenergization of relay 405 is without effect at this time other than to prepare the ringing circuit.

It will now be assumed that the calling subscriber Wishes to talk to any one of a group of subscribers, each having the same group call number. Assuming further that the desired group is the first group diagrammatically illustrated in Fig. A, the calling subscriber will then dial the group number, or in this case the digit 1. Responsive to the calling subscriberls dialling the digit 1, the line relay 402 is operated in the same manner as previously described, and upon its deenergization, responsive to the impulse, it will close at armature 419 the circuit for operating the rotary magnet. The circuit for operating the rotary magnet may be traced as follows:

ground by way of off-normal springs 414,

armature 418 and its working contact, normally closed springs controlled by armature 419, armature 448 and its resting contact, armature 430, armature 416 and its working contact, and winding of rotary magnet 411 to battery. The rotary magnet 411 operates the wipers in engagement with the first set of bank contacts, and wiper 464 will therefore be in engagement with test contact 480 (Fig. 5A) which has a battery potential thereon.

The operation of the rotary connector now depends u on whether the first line associated with the rst set of contacts is busy or idle. If busy, there will be a ground potential on the test contact engaged by test wiper 465 and accordingly busy relay 404 energizes over the following circuit: ground by way of grounded test contact, wiper465, armature 441 and its workin contact, and winding of busy relay 404 to attery. Busy relay 404, upon energizing, at armature 429 prepares the circuit for connecting the busy tone to the calling line; at armature 431 prepares a locking circuit for itself which is completed when slow acting relay 406 falls back; at armature 433 prepares a circuit for relay 409; and at armature 432 opens the circuit to the upper winding of line relay 402 which deenergizes when re ay 406 falls back. When slow acting relay 406 falls back a short interval of time after the directive rotary impulses, a circuit may be traced for energizing relay 409 as follows: from ground by way of armature 457, armature 445, armature 433 and its working contact, lower winding of relay 409, normally closed springs controlled by armature 461,

.. test wiper 464, test contact 480, and through resistance 481 to battery. Relay 409, upon energizing, at armature 458 opens the circuit of slow acting relay 406; at armature 459 com- Eletes a locking circuit for itself extending y way of grounded test contacts accessible to test wiper 465; at armature 461 opens its original energizing circuit and closes an en ergizing circuit through the lower winding of relay 402; and at armature 462 grounds such armature for a purpose which will be described hereinafter. The circuit for ener gizing line relay 402 may be traced as follows: ground by way of interrupter contact 413 of the rotary magnet, lower winding of linerelay 402, normally open springs controlled by armature 461, and resistance 460 to battery. Line relay 402, upon energizing, at armature 419 again completes the circuit for maintaining slow acting relay 408 in energized positlon and also closes a circuit for operating the rotary magnet 411 as follows: ground by way of ofi-normal springs 414, armature 418 and its working contact, working contact of armature 419 and said armature, off-normal springs 420, working contact of armature 458 and said armature, armature 416 and its working contact, and winding of rotary magnet 411 to battery. The rotary magnet operates and steps the wipers to the next set of contacts in the desired group. Near the end of its stroke, rotary magnet 411 at armature 413 opens the circuit of line relay 402, whereupon said relay deenergizes. Line relay 402, upon deenergizing, at armature 419 opens the circuit of the rotary magnet and slow acting relay 408. If the next trunk line is busy, relay 409 will be maintained energized by way of the grounded contacts in engagement with Wiper 465 and therefore, when the rotary magnet restores armature 413, the line relay is again energized and again causes the rotary magnet to step the wipers to the next set of bank contacts. This cycle of operation continues until an idle line or the last line in the group is reached.

Assuming that all the lines in the desired group are busy, the connector will rotate its wipers into engagement with the last line in the group where a ground potential will be encountered by wi er 464 which will prevent line relay 402 rom again energizing. The ground on the last test contact such as 483 extends by way of wiper 464, working contact of armature 461 and said armature, through relay 402 to ground at armature 413, thereby shunting relay 402. Relay 409, however, is maintained in energized position from ground encountered by the test wiper 465. Since the line relay 402 is not again energized to close the circuit to the rotary magnet, the wipers accordingly come to rest on the bank contacts of the last line in the group. The busy tone is now transmitted to the calling subscriber by way of conductor 421, resting contact of armature 422 and said armature, armature 429, resting contact of armature 447 and said armature, to the upper talking conductor 341 from whence it is transmitted to the' calling subscriber in the well known manner.

Returning to the first selector repeater, the loop circuit of relay 223 will be interrupted when the circuit through the upper winding of line relay 402 of the connector is opened by the energization and locking up of the busy relay 404. Relay 223 accordingly deenergizes. At armature250 relay 223 opens not close the meter circuit at armature 256.

Responsive to the busy tone, the calling sub-- scriber will replace h1s receiver and release the switches in the same manner as will be described hereinafter.

Assuming now that one of the group of subscribers lines, for instance subscriber A, is idle, the connector will rotate its wi ers into engagement with bank contacts 46 to 470, inclusive, and since the line of substa tion A is idle there will be a battery potential on test contact 469 instead of ground and therefore relay 409 will be deenergized. Relay 409, upon deenergizing, at armature 459 opens its own locking circuit and also closes an energizing circuit for switch-through relay 407 as follows: from ground by way of the lower windin of switching relay. 407, resting contact 0% armature 459 and said armature, working contact of armature. 455 and said armature, resting contact of armature 441 and said armature, wiper 465, bank contact469, winding of switching relay 471 of line switch LS, and through the windin 7 of rotary magnet 473 to battery. Relays 40 and 471 energize over the above-traced circuit but the stepping magnet 4730f the line switch LS does not receive sufficient current to permit it to operatively energize. The combined switching and cut-off relay 471 of the line switch LS disconnects the called subscribers line from battery and ground in the well known manner. Relay 407, upon energizing, at armature 447 opens a point in the circuit of the upper winding of line relay 402 causing relays 223 and 227 in the first selector repeater to be denergized in the manner previously described; at armature 448 opens the circuit to the rotary magnet; at armature 449 connects direct ground to test contact 469 and multiples thereof to render the called line busy and to hold the called line switch in operated. position; at arm- -m 450 opens the locking circuit of the busy relay 404 which now deenergizes; at armature 451 closes a locking circuit for itself in series with the vertical magnet 410; at armature 452 completes the ring-backcircuit through condenser 454; and at armatures 446 and 453 completes the ringing circuit from interrupted generator. Due to the high resistance of the upper winding of switching relay 407 the vertical magnet does not receive sufiicient current to operate. The ringing circuit for ringin the called subscriber may be traced as ollows: from inenergizes when the switching rela terrupted generator INT GEN, conductor 439, lower winding of ring-cut-ofi relay 405, resting contact of armature 438 and said armature, armature 453, wiper 466, contact 470, over the called subscribers. line including the ringer of the called line, contact 467, wiper 463, armature ,446,and armature 434 and its resting contact to ground.

When the called subscriber answers, ringc'ut-oif relay 405 is energized over its lower winding. Ring-cut-olf relay, upon energizing. at armatures 434 and 438 disconnects the ringing current and completes the talking circuit; at armature 436 again completes a lockingcircui-t for itself which extends by way of the working contact of armature 448 i I and said armature to ground at either armatures 435 or oif-normal springs 414; and at armature 437 opens a point in the circuit to vthe release magnet 412.

Returning now to the first selector repeater, it will be-remembered that relay 2% de- 407 of the connector switches through an that relay 223 opens the locking circuit of relay 227,

thereby permitting relay 227 to release. As

soon as the calledman' answers, ring-cut-off relay 405 of the connector completes a circuit for energizing relay 223 of the first selector repeater over the called subscribers loop. Relay 223, upon energizing, at armature 250 completes anenergizing circuit for slow acting relay. 225 as follows: ground by way of armature 250 and its working contact, arma ture 270 and its resting contact, resting contact of armature 263 and said armature, and

winding of slow acting relay 225'to battery.

Slow acting relay 225, upon energizing, at

armature 256' opens a point in the circuit to 1 the release magnet 232 and also prepares a point in the circuit for operating the calling subscribers meter; at armature 257 opens a point in the holding circuit for relay 223; at armature 258 completes a locking circuit for itself; at armature 259 prepares a locking circuit for relay 226; and at armature 260 prepares a circuit for grounding the lower talking conductor for supervisory purposes. Talking battery to the calling subscriber extends by way of the windings of relays 224and 221 over the calling subscribers loop and talking battery to the called subscriber extends through the windings of relays 224 and 223 over the called subscribers loop. The-talking circuit to the various switches may be traced by the heavy talking conductors.

After conversation and responsive to the called subscriber replacing his receiver, relay 223 in the first selector repeater deenergizes and prepares the metering and release circuits at armature 249 and at armature 250 opens one of the locking circuits of slow acting relay 225.

' slow to release.

When the calling subscriber'replaces his receiver linerelay 221 releases. Line relay 221, upon deenergizing, at armature 240 opens a point in the circuit ofrelay 223 and at armature 241 closes a short circuit around release relay 222, thereby renderingsuch relay Before the release relay 222 deenergizes, a circuit may be .traced from ground by Way of armature 247, normally closed springs controlled by armature 241, armature 283 and its working contact, and through the upper winding of relay 226 to battery. Relay 226, upon energizing, at armature 261 opens a point in the circiiit of line relay 221 and at armature 262 connects an additional ground to release trunk conductor- 215 by way of armatures 278 and 255 to maintain the calling line switch in operated position during the metering operation. After an interval, release relay 222 releases and at armature 242 opens another point in the circuit of line relay 221 sothat the calling subscriber can not interfere with the metering operation. At armature 244 relay 222 closes a circuit for operating the calling subscribers meter as follows: ground by way of meter magnet M, armature 208, wiper 212, conductor 216, armature 256, armature 275, armature 244, armature 249, olf-normal springs 248, and to the winding of release magnet 232 to battery. Release magnet 232 is not energized over this circuit on account of the high resistance of the meter magnet M. At armature 245 release relay 222 removes one of the ground connections from release trunk conductor 215; at armature 246 removes'one of the locking grounds from the locking circuits of relays 225 and 226 as well as removing ground from release trunk conductor 302; and at armature 247 release relay 222 opens the locking circuits of relays 225 and 226. After an interval of time, relays 225 and 22.6 will release, it being remembered that relay 226 is slightly slow to release due to the short circuit from its lower winding. Relay 226, upon deenergizing, at armatures 262 removes ground from the release trunk conductor 215, thereby permit ting the calling line switch LS to release in the well known manner. Relay 225, upon releasing, at armature 256 opens the metering circuit and closes a circuit for operating the release magnets as follows: ground by way of armature 256, armature 275, armature 244,

armature 249, off-normal springs 248, and

through the winding of release magnet 232 to battery. Relay 226 at armature 262 also opens the locking circuit of switching relay 229 whereupon such relay deenergizes and disconnects the talking conductor. By the operation of the release magnet 232 the first selector repeater is returned to its normal position in the well known manner, thereby opening the off-normal springs 248 which in turn opens the circuit of the release magnet.

In case the calling man hangs up before the called man, line relay 221 will release and open the circuit of relay 223 at armature 240 so that the release of the first selector repeater is the same as if the called man had replaced his receiver.

When ground is removed from release vtrunk conductor 302 by the deenergization of releaserelay 222, relays 306 in the intermediate selectors and relay 401 of the connector deenergize. Relays 306 in the intermediate selectors, upon deenergizing, at armatures 322 close the circuitfor their respective release magnets, thereby causing the release of the intermediate selectors in the well known manner.

When the combined'change-over and release relay 401 in the connector releases, said relay at armature 415 opens the circuit of relay 407 in case the called subscriber has replaced his receiver. In case however, the called subscriber has not hung up his receiver a circuit for maintaining switching relay 407 energized may be traced as follows: from ground by way of upper winding of switching relay 407, armature 451, normally closed springs controlled by armature 415,

working contact of armature 438 and said armature, armature 453, over the called subscribers loop to armature 446, armature 434, armature 447 and its working contact, armature 415 and its resting contact, and winding of vertical magnet 410 to battery. Relay 407 maintains ring-cut-ofiv relay 405 in operated positionand therefore the connector does not release until the called man hangs .net 412. Switching relay 407, upon deenergizing, responsive to the deenergization of relay 401 or the calling subscriber replacing his receiver at armatures 446 and 453 opens the talking circuit; at armature 448 opens the holding circuit of ring cutofi relay 405 and removes ground from release trunk 342 which has been placed thereon by the deenergization of relay 401 in order to make the connector test busy as long as it is held by the called subscriber; at armature 449' removes ground from test contact 469 thereby rendering the called line idle and permitting the release of relay 471 to normal; and at armature 451 opens its own locking circuit. Ring cut-ofl relay 405, upon deenergizing, at armature 437 closes the circuit to the release magnet 412 whereupon said magnet releases the switch in the well known manner. All of the apparatus involved in the local connec- III Ill

tor is therefore recallin tion' is now released and may be used ex tend other calls.

Toll call to subscriber A I Havin described the detailed operation which ta es place in the establishment of a connection, subscriber A to subscriber A, we will now describe the operation which takes place when subscriber A is desired ina toll connection. It will now be assumed that the toll operator at the switchboard'shown in Fig. 1 desires to extend a connection to the line of substation A,-either because he has received a long distance call for him, or because he himself has requested that a long distance connection be set u and the operahim. The operations are the same in hot csases. To extend the connection to the line of substation A, the operator inserts the plu of her cord circuit, for example, the (plug of the cord circuit CC, into the jack of a toll service trunk line terminating at her switchboard and extending to the transmission selector repeater in the local'automatic exchange. 7

Responsive to the insertion of a plug P into jack J a circuit may be traced for energizing the, line relay 107 of the transmission selector repeater as follows: ground by way of normally closed springs controlled by armature 125, lower left hand winding of repeating coil, trunk conductor 10, ring spring of jack J, ring contact of plug P, normally closed springs of the combined dial and ringing key K tip contact of plug P ,tip springs of jack J, trunk conductor 9, upper eft hand winding of the repeating coil in the transmission selector repeater, normally closed springs controlled by armature 123, normally closed springs controlled by armature 128. and to the lower winding of line relay 107 to battery. Polarized relay 2 is not energized over the above traced circuit because the direction of current flow is not in the proper direction. Line relay 107, upon energizing, at armature 134 prepares a circuit to the upper winding of relay 113 and also prepares the loopre eating circuit. mature 135 relay 10% opens a point in the circuit of the release magnet 120 and closes a circuit for energizing relay 108.- Release 108, upon energizing, at armature 137 prepares aholding circuit for relay-.113 during impulsing; at armature 138 grounds therelease trunk conductor 121; at armature 139 opens a further point in the circuit of the release magnet and prepares the impulsing circuit to the vertical magnet 118; and at armature 141 closes a circuit for energizing relay 106 by way of armature 126 and its lower winding. Relay 106, upon energizing, at armature 131 disconnects the ringing circuit and closes a circuit for energizing relays 113 and 116 in series; atarmature 132 closes a shunt around armature 126 inorder to maintain 'it- At arthe call to the line of substation A. .the operator has dialled the complete numself in energized position in case relay'102 should energize prematurely; and at armature 133 disconnects generator ground and prepares a locking circuit for the lower windmg of relay 113. The circuit for energizing re ays 113 and 116 may be traced as follows: ground by Way of armature150 and its restmg contact, upper Winding of relay 113, working contact of armature 134 and said armature, normally closed springs controlled by armature 177, armature 154, up er right hand winding of repeating coil, wor ing contact of armature 131 and said armature, resting contact of armature 166 and said armature, armature 175, normally closed sprin s controlled by armature 182, and through t 1e upper winding of relay 116 to battery, Relay 113, u on energizing, at armature 163 prepares a locking circuit for relay 116. Relay 116, upon energizing, at armature 174 prepares the dial tone circuit; at armature 175 opens a point in the original energizing circuit of relay 116; at armature 176 prepares a circuit for maintaining relay 113 energized during the impulsing period at armature 177 opens a further point in the initial energizing circuit of relays 113 and 116 and substitutes aholding circuit for relays 113 and 116 in series; at armature 178 opens the circuit of relaly 102 which does not have time to operate w en the release trunk 121 was grounded because of its mechanical construction and also closes a circuit for energizing relay 114; at armature 179 opens the circuit of relay 104 and also closes a locking circuit for itself; at

mature 17 8 and said armature, resistance 173 and winding of relay 114 to battery. Relay 114, upon energizing, at armature 165 completes the circuit for transmitting the dial tone to the operator; at armature 166 opens a point in the talking circuit; at armature 16 prepares a circuit for relay and at armature 169 prepares a circuit for relay 1'15. Responsive to the seizure of the switch, relays 106, 107, 108, 113, 114, and 116 are operated in order to prepare the transmission selector repeater for operation. 7

The callmg operator now throws her combined dialling and ringing key into dialling position, thereby connecting up her common calling device CD in bridge of the tip and ring conductors of the plug P. The opera-. torwill now operate the calling device in accordance with the digits necessary to trunk After her she will restore the combined dialling and r nging key to normal position.

Responsive to the operation of the calling The rotary magnet will continue to operate in a buzzer like manner until the test wiper device the circuit of line relay 107 is intermittently opened and closed and said relay intermittently deenergizes and energizes responsive thereto. Each time line relay 107 falls back a circuit may be traced for operating the vertical magnet and slow acting relay 109. The circuit for energizing the vertical magnet may be traced as follows: ground by way of normally closed springs controlled by armature 135, armature 139 and its working contact, armature 182, and through the winding of vertical magnet 118 to battery. A branch of this circuit also extends through the winding of slow acting relay 109 and such relay due to its slow. acting characteristics is maintained in operated position during the dialling period. At armature 134 line relay 107 closes a circuit for maintaining relay 113 in operated position during impulsing. This circuit extends by way of armature 150, the

7 upper winding of relay 1'13, make before break springs controlled by armature 134, armature 137, armature 136 and through resistance 183 to battery. Slow acting relay 109, upon energizing, at armature 143 opens a point in the circuit of slow acting relay 110 and at armature 144 opens a point in the circuit for the rotary magnet 119. By the operation of the rotary magnet the switch wipers 191 to 193, inclusive, are operated opposite the desired levels of bank contacts inwhich an intermediate selector such as shown in Fig. 4 terminates. I

A short time after the receipt of the first series of impulses slow acting relay 109 deenergizes and at armature 144 closes the circuit for rotary magnet 119 which may be traced as follows: ground by way of arms;- ture 141, armature 144, armature 140, 011'.- normal s rings 181 which were closed on the first vertical step of the switch, resting contact of armature 185 and said armature, interrupter springs 158 of the rotary magnet, and winding of rotary magnet 119 to battery. By the operation of the rotary magnet, the switch wipers are rotated into engagement with the first step of bank contacts 1n the desired level. The operation of the transmission selector repeater now depends upon whether the first trunk line is busy or not.

192 encounters an idle trunk which will have a battery potential connected to its associated test contact, such as 195. Assuming that the first idle trunk encountered by test wiper 192 comprises the conductors 197 to 198 then there will be a battery potential on test contact 195 extending from the second intermediate selector through the resistance, such as 345, over conductors 333 and.198 to bank contact 195. As soon as test wiper 192 encounters the test contact 195 having battery potential thereon, switching relay 117 energizes over its upper winding from the net; at armature 186 opens the circuit to the vertical magnet 118; and at armatures 182 and 187 closes a point in the talking circuit thereby closing a circuit for energizing the line relay in the intermediate selector. The line relay of the seized intermediate selector energizes and prepares the switch for operatibnin the same manner as previously described.

The circuit for energizing the line relay of the seized intermediate selector extends from ground by way of armature 150, upper winding of relay 113, working contact of armature 134 and said armature, working contact of armature 177 and said armature, working contact of armature 182 and said armature, wiper 191, contact-194, conductor 197, conductor 332, winding of line relay, such as line relay 304, conductor 334, conductor 199, bank contact 196, wiper 193, armature 187 annature 181 and its working contact, and through resistance 172 to battery. Relay 113 is maintained energized over the above traced circuit. Y

The operator may ,now dial the next digit of the called number and responsive thereto line relay 107 in the transmission selector re- 1 peater is operated in the same manner as previously described. Each time the circuit of line relay 107 is opened, said relay deenergizes and at armature 134 opens the circuit of the line relay in the intermediate selector. Relay 113, however, is maintained from battery through resistance 183 over the circuit previously traced. Relay 109 is again energized but does not perform any useful functions at this time. Responsive to the interruption in its circuit, the line relay of the intermediate selector operates in the same manner as previously described to cause the intermediate selector to seize an idle trunk extending to an idle connector. Assuming that the connector shown in Fig. 5 is again seized, then line relay 402 again operates, this time from ground at armature 150 and battery through resistance 172 over the talking conductors extending between the transmission selector repeater and the connector. It will be noted that the flow of current extending over the talking conductors from the transmission selector repeater to the connector is reversed with respect to the flow of current extending over the talking conductors from the first se- I the same manner as previously described when the release trunk conductor is grounded. lhe operator may now dial the next digit in the number of the called subscriber. Responsive thereto, line relay 107 in the transmission selector repeater repeats the impulses to line relay 402' in the rotary connector, thereby operating the connector wipers opposite the desired groupof bank contacts in which the called line terminates. Relays 406, 408, and 401 operate in the same manner as previously described. --When relay 401 energizes after the first series of impulses, said relay closes a circuit at armature 417 through resistance 426 to the lower wind- 7 ing of marginal relayv 403. The fiow of current through both the winding of relay 403 is now suflicient to operate armature 425. Armature 425, upon closing its make-contact, short circuits the resistance 426, thereby causing the marginal relay to pull all the way up and lock to the grounded release trunk conduotor 342. Relay 403, upon energizing, at armature 422 opens a point in the circuit extending to the busy tone machine; at armature 423 maintains the ring-cut-ofi relay in energized position so that the operator may control the application of ringing current; at armature 424 disconnects direct ground so that ground through a resistance 428 will be applied to the test contact of the called line when the connector switches through; and at armature 427 prepares a circuit for grounding conductor 343.

Assuming now that the operator desires to connect with a particular line, such as substation A', in a group of lines all having the same common called number, she will therefore dial the individual call number of substation A. Assume further that substation A is the desired subscriber and that the line of substation A terminates in the fourth set of contacts in the level to which the connector has been operated, the operator will therefore dial the digit 4. Responsive to the operator dialling the digit 4, the line relay in the transmission selector repeater repeats the impulses to line relay 402 in the rotary connector whereupon line relay 402 operates the ro tary magnet to cause the wipers to come to rest in engagment with the fourth set of bank contacts in the selected level, or the bank contacts individual to the called subscriber A. Since only the first contact in a group has battery potential on test contacts such as con tacts 480 and 485, (Fig. A) relay 409 will not be energized because its circuit is opened at armature 445 when wiper 464 passes over the first contact in the group.

Assuming now that substationA' is idle, switching relay 407 will energize in series with switching relay 471 of the called line switch LS in the same manner as previously described. Switching relay 407, upon energizing, at armature 447 opens the circuit of ine relay 402; at armature 448 opens the rotary magnet circuit; at armature 449 connects ground through resistance 428 to test contact 469 thereby applying a discriminating ground potential instead of direct ground; at armature 451 locks itself in series with the vertical magnet 410; and at armatures 446 and 453 connects up the talking conductors. Line relay 402,'upon deenergizing, at armature 419 opens the circuit of slow acting relay 408. After an interval, slow acting relay 408 deenergizes and at armature 456 prepares a, oint in the circuit for the lower winding 0 switching relay 407.

Returning now to the toll transmission selector, the circuit of relay 113 is opened when switching relay 407 of the connector opens the loop at armature 447 and accordingly relay 113 deenergizes'. Relay 113, upon deenergizing, at armature 163 opens the ocking circuit of relay 116 whereupon the latter relay deenergizes. Relay 116, upon deenergizing, at armature 174 prepares the busy circuit; at armatures 175 and 181 preparesthe talking circuit; at armature 176 opens a point in the holding circuit of relay 113; at armature 177 disconnects relay 113 from wiper 191; at armature 178 opens the circuit of relay 114 and completes a circuit for relay 102; at armature 179 prepares a point in the circuit for relay 104; and at armature 180 closes the circuit for energizing relay 115 which energizes and causes slow acting relay 109 to energize also. After a short interval of time, relay 114 deenergizes'and at armature 165 opens the busy tone circuit; at armature 166 completes the talking cirouit; at armature 167 prepares a point 1n the circuit. for relay 110; and at armature 169 opens the circuit of relay 115 which deenergizes and causes relay 109 to deenergize. A short interval of time after its circuit is closed, relay 102 energizes and atarmature 122 prepares the ringing circuit. At armature 126 relay 102 opens a point in the holding circuit of relay 106 which is held up, however, over the back contacts of the A. C. relay 105; at armature 124 completes the circuit for the A. C. relay 105; and at armatures 123 and 125 reverses the flow of current over trunk conductors 9 and 10 so that the polarized relay 102 in the cord circuit CC operates to light the lamp L when the opera tor restores the dial key.

By the operation of the lamp L, the operator knows that the called line is idle, and accordin l momentarily operates her ring- 111g key thereby a plyin generator to trunk conductors 9an 10. C. relay 105 operates responsive thereto and opens the locking circuit of relay 106 which accordingly deenergizes. Relay 106, upon deenergizing, at armatures 131 and 133 connects the generator to the called line. The rin 'n I circuit extends by way of generator GfiN? conductor 190, armature 122, up er winding of relay 106, resting contact of armature 131 and said 'armature,over the heavy talking conductors to the called subscribers line and thence back to ground at armature 133. Responsive to the operation of this bell, the called subscriber will remove his receiver, thereby causing the operation of ring-cut-oif relay 106 over the previously traced ringing circuit. Relay 106, upon energizing, at armature 132 again closes its locking circuit and-at armatures 131 and 133 completes the talking circuit and also com letes a circuit for energizing the battery feed relay 113 overthe called subscribers loop. Relay 113, upon energizing, at armature 163 completes an obvious circuit for energizing relay 104. Relay 104, upon energizin at armatures-128 and 129 disconnects all battery and ground connections from the trunk conductors 9 and 10 thereby providing a dry trunk in order to improve the talking circuits and also at armature 128 closes a local holding circuit for the two windings of relay 127 in series. When the battery and ground connections are cut off from the trunk conductors 9 and 10, polarized relay 2 in the cord circuit deenergizes and puts out the lamp, thereby signalling the operator that the called man has answered. The talking circuit may be traced over the heavy talking conductors in the well known manner.

After conversation and responsive to the called subscriber replacing his receiver, relay 113 in the transmission selector repeater deenergizes and at armature 163-opens the circuit of relay 104. Relay 104, upon deenergizing, again connects battery and ground to the trunk conductors 9 and 10 thereby operating the polarized relay 2 in the cord circuit to light the lamp. L. The operator, upon perceiving the lighted condition of the lamp L, will remove the plug P from the jack J, thereby opening the circuit of line relay 107.

' Line relay 107, upon deenergizing, at armature 135 opens the circuit of release relay 108 which thereupon deenergizes. At armature 138, release relay 108 removes ground from release trunk conductor 121 thereby causing the release of relay 117 and the release of the intermediate selector and connector as previously described. At armature 141, slow to release relay 108 opens the locking circuit of ring-cut-off relay 106 and at armature 139 closes a circuit for energizing the release magnet 120. By the operation of the release magnet 120 the transmission selector repeater is-returned to its normal position in the well known manner.

Having described the operation which takes place in establishing a toll call to an idle subscribers line, an explanation will now be given of the operation which takes place when the operator wishes to complete a toll connection to a subscribers line which is busy in an established local connection. It will now be assumed that substation A is the called arty in anestablished local connection and that the toll operator wishes to establish a connection to such party.

The operation of the apparatus will be the same as described up to the time that the connector shown in Fig. 5 comes to rest with its test Wiper 465 in engagement with test contact 469 or multiples thereof. Since substattion A is busy in a local connection there will be a direct ground potential on test contact 469 and multiples thereof and accordingly the busy relay 404 of the connector will be energized and locked up as previously described. In this case, however, the circuit to the upper winding of relays 402 and 403 are opened at armature 432 of the busy relay and ture 456 relay 408 connects the lower winding of relay 407 to conductor 343 as follows: ground through the lower winding of relay 407, armature 456, armature 427, armature 432, armature 452, and conductor 343.

Returning now to the toll transmission selector, relay 113 deenergizes when ground through the lower winding of relay 407 is connected to conductor 343 in place of the line-relay bridge. Relay 113 deenergizes slowly because its upper winding is shunted. The shunt circuit may be traced as follows: from grounded conductor 343, contact 338, wiper 335, conductor 332, conductor 197, contact 194, wiper 191, armature 182, armature 177 and its working contact, armature 134, and upper winding of relay 113 toground at armature 150. Relay 113, upon deenergizing, at armature 163 opens the locking circuit of relay 116 which relaythereupon deenergizes. Relay 116, upon deenergizing, and at armature 175 completes a circuit for maintaining'relay 114 in operated position. This circuit extends from ground through the lower winding of relay 407, over the circuit previously traced to armature 175 and thence by way of armature 166, resistance 173 and Winding of relay 114 to battery. Relay 407 of the connector is not energized over this circuit on account of .the combined resistances' of the winding of r'elay'114 and resistance 173. A circuit may now be traced by way of the direct groundon'said contact 469,01- multiples thereof, to conductor 341 from whence it extends by way of bank contact 340, Wipers 337, conductor 334, conductor 199, contact 196, wiper 193, armature 187,

- armature 181, armature 169 and its left hand in the cord circuit. The busy tone applied byway of conductor 148 indicates to the calling operator that substation A is busy in'a local connection.

In case the operator desires to cut in on the established local connection she will operate the key K thereby grounding conductors 9 and 10in an obvious manner. He-

sponsive to groundin conductors 9 and 10,

the circuit of the lower winding of relay 113 and at armature 153 prepares a point in the circuit for grounding conductor 199. At armature 151, relay connects battery potential by way of the low resistance winding of rotary magnet 119 to the winding of relay 114 and thence by way of resistance 173 to conductor 197. The connection of this battery potential shunts relay 114 thereby causing said relay to deenergize and also causes the switching relay 407 in the connector to energize over the circuit previously traced through its lower winding. Two-step relay 111, upon energizing in-its first step, operates only armatures 156 and 157. At

. armature 156 relay 111 closes a circuit from ground at armature 141 through both its windings in series to battery. "Relay 111, however, will not energize over this circuit because the lower winding is shunted by ground at armature 149. At armature 157, relay 111 closes a shunt around the contacts of armatures 167 thereby preparing a new circuit for holding relay 110 when slow actcircuit.

ing relay ll4deenergizes. When's'low-acting relay 114 finally falls back, said rela at armatures 166 and 169 prepares the ta king Returning now to the connector and whenrelay 407 energizes over the above-traced cir-' cuit from-the transmission selector repeater, said relay-at armatures 446 and 453 closes the talking circuit at armature 447 disconnects conductor 341 from grounded contact 469; at armature 449 connects ground through discriminating resistance 428 to test contact 469; at armature 450 opens the. circuit to the busy relay 404 which deenergizes; at armature 451 completes a locking circuit for itself in series with the 'vertical magnet; and at armature 452- disconnects the lower winding of relay 407 from conductor 343. At this time only relays 401,

403, 405,, and 407 of the connector are in operated position. I

In the transmission selector repeater differential relay 103 deenergizes when the operator restores the ke K and said relay opens the circuit of s ow acting relay 110.

Slow acting relay 110, upon deenergizing, removes ground from armature 149, thereby permitting the two step rela 111 to fully operate to its second step. wo-step relay 111, upon energizing in its second step, at armature 154 opens the circuit to the upper winding of relay 113; at armature 155 prepares the circuit for opera-ting'the two step relay 112 in its first step; .at armature 158 opens a point in the circuit extending to the lower winding of rela 113; andat armature 159 prepares a clrcuit for grounding conductor 199.

The operator may now converse with the desired subscriber and inform him of the desired toll connection. In case the operator desires to break down and release the local connection she may do so by again operating tial relay 103 to operate. Relay 103, upon energizing, closes a circuit for energizing relay 110 as follows 1 round by way of armature 163 and its resting contact, armature 143, armature 157, armature 127, and Winding of relay 110 to battery. At armature 153 relay 110 grounds conductor 199 and at armature 149 completes an obvious circuit for energizing two-step relay 112 in its first step. Two-step relay 112 does. not operate in its second step when it closesarmature 161 because of the shunt circuit around its lower winding. Two-step relay 112 operates only armatures 160 and 161 in its first step and therefore a circuit may be traced from ground by way of armature 163 and its resting contact, armature 143, armature 157, armature 145, armature 160, working contact of armature 131 and said armature, armatures 166, 175, and 182 to conductor 197.

Images