US1484614A - Telephone system - Google Patents

Description

Feb.. 26 1924. Y 31,4%,6314

vv. P. ALBERT 'lET JEPI'IOIILA SYSTEM Filed Dec. 16. 1920 5 sheets-sheet 2 RES mm. E

Awe.

Pune

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Feb.- 26 1924.

Feb. 26 1924.

` y w. P. Mama-r TELEPHONE SYSTEM Filled new. m. 92o

heb. 2d, i924.

Patented Matin WALTER P. ALBERT, F EAST ORLNCTE, NEVI JERSEY, ASSGNOR TO WESTERN ELEC- TRIO COvIPANY, INCORPORATED, OF NEYV YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

Application ined December ie, i920.

To all wim/m t may concern.'

Be it known that l, l/VALTER l). ALBERT, a citizen of the United States, residing at East Grange, in the county of Essen, State 5 of N ew Jersey, have invented certain new and useful lmproveinents in rlrelephone Systems, of which the following is a full, clear,

concise, and enact description.

' This invention Vrelates to telephone eX- change systems and particularly to systems of the semi-automatic type, involving the services of operators as well as automatic switches for completing talking connections. ln certain semi-automatic systems the subscribers lines are terminated in calling Ajacks at operators positions in the central otlice. So far as the subscriber is concerned his line is identical in all respects to an ordinary manual line. To make a call he removes his receiver from its switch-hook and communicates the wanted number to the responding operator. At the central ofice, too, the duties of the operator correspond in some respects to those of the usual manual operator. She answers the calling line by inserting the plug of an idle cord circuit at her position in the jack of the calling line. @n receiving the number of the desired line from the calling party she then proceeds to record the same on a set of keys, which determine the operation of a register controlling mechanism to govern the selective operation of automatic switches in the extension of the call. ln order that the operator may be relieved of the manipulation of keys, each time a call is answered, for connecting` her telephone set to the calling line and disconnecting it therefrom certain instrumentalities are used to accomplish theY same automatically.

The object of the present invention is the provision, in a system of the above described character, of an arrangement for automatically connecting the operators set to the :ailing line and disconnecting' the same therefrom, wherein a connecting relay acts in response to certain operations to complete u talking connection between the operators set and the calling line and thereafter acts to sever said connection responsive to the register mechanism when such mechanism has reached a certain stage in its operation.

n. feature of the invention relates to the provision of a relay which acts when the operator responds to the call to connect the Serial No. 431,198.

calling line to the operators set and later acts in response to the register mechanism when such mechanism has completed its control of the automatic switches,'to disconnect the calling line from the operators set and to extend such line through to said automatic switches.

@ther features of the invention will become more apparent from a consideration of the following detailed description and the appended claims.

ln the 'accompanying drawing, which constitutes a part of this application, Figs. l to 5 inclusive, when arranged in the order shown in Fig. 6, illustrate a telephone eX- change system in `which the features of the present invention are incorporated. Fig. l shows a subscribers telephone line terminating in an answering jack before an operators position in the central otlice. This figure also shows an operators cord circuit provided with an answering plug and means for associating the operators telephone set with the cord circuit.

Fig. 2 shows one of a plurality of cord finder switches having access to the several cords at the operators position and serving to associate an idle register sender with a desired one of said cord circuits.

Fig. 3 illustrates the keyboard at the operators position consisting of a plurality of rows of oice and numerical keys upon which the designations of called lines are recorded. Also this figure shows in detail the registers and sender individual to the cord finder in Fig. 2, the function of which is to register the designation set up on the operators keyboard to determine the selective operation of the switches in the extension of the connection.

ln Fig.v 4l there is shown to the left two automatic switches, namely, a district switch and an office switch. The district switch shown at the extreme left of the figure is individual and is connected directly to one of the cord circuits at the operators position. At the right of the ligure is shown an incoming` switch to which connections are extended from the office selector.

Fig. 5 shows a second group selector in the same office and a final selector for completing the connection to called subscribers type arranged to'be operated by stepping magnets first in a group selecting movement and next in an automatic trunk hunting movement. switch shown in F ig. 5 differs frointhe preceding switches in that both its primary and secondary operationsv are directive movement-s effected by the last two series of impulses. V y

The cord iinder switch, the several elements ot which are located within the broken rectangle at the upper left-hand corner otV Fig. 2, consists of an ordinary single movement rotary step-by-step switch.

Tlh'is'switch 4is provided with several brushes 202, 203, 204, etc., which are driven over corresponding arcuaterows of terminals by a stepping magnet 200. The several terminals oi: the Contact banks ot the cord finder switch are each individual to acord circuit at the operators position. The function of the cord finder switch is to Search for and find the particular operators cord circuit that has been taken for use in responding toa calling line. Y

The operators keyboard shown'in Fig. 3, one of which is provided for' each operators position'7 consists ot four rows ot' office keys 300, 30,5, 310, and 315, and Jfour rows ofnufmerical keys 320, 325, 330, and 335, and also a set of station keys 34:0. In Vcoinmonto the operators keyboard there is provided a plurality of register senders. VEach of these register senders comprises four oiiice registers generally designated as 302, 307,312, and 317, and four numerical registers 322, 327, 382, and 337. and also a station register 34:2. These registers comprise a small rotary step-by-step switch having two movable brushes and a stepping magnet for driving said brushes over their respective rowsot' terminalsf rlhe brushes vand the terminal blanks and the stepping magnets together with certain control elements are, in the case of each of the sev- Aeral registers, shown as conined Within the o space of theV respective broken rectangles in Fig. 3. Y

For controlling the various operations of vthe registers a sender control switch is pro- 'videdf This switch is of Vthe step-by-step tyi'ie consisting ot' a` stepping ii'iagiiet 372 anda plurality ot Contact elements operated by Ysaid magnet. The step-by-step contactV elements ot the sender control switch are located iii various places throughout Fig. :l ot the drawing and their closing positions are illustrated by means of oi'dinals adjacent to said contacts. ln addition to the registers and sender control switch there is provided a time measure switch generally designated at 240. rlhe purpose oit'. this switch is Vto govern the advance ot the sender control switch from one posit-ion to another Vand to Vpostpone the time at which The final selector or Vconnector 'Y adapted to control varying kinds of connecthe succeeding` registers of the sender are rendered effective for a purpose more clearly to be set forth hereinafter. i

inasmuch as the register sender must be it isadjiisted to'in'tluence the operation of the` sender rentrol switch during the time the register sender is exercising` its control over the Vselective switches. The class switch consists of a plurality of step-by-stepV elements arranged to be moved from position lo position lby stepping magnet 214. The several switchingelements governed by the magnet 214-, are located within the area set olif by the broken line at the right ofV Fig. Q and their closing positions are designated by the adjacent ordinalsV 'A complete register controlling mechanisiii consists ot a cord finder switch, a set ot otiive and numerical registers, a `time measuringswitch and the associated circuits and other controllingelements. There may be's'everal of these register controlling merhanisms to serve .an operators position.

Consel;uentlyA` an allotter-switch is used for assigning an idle register sender for use so that only one such sender will be appropriated and associated with the cord circuit when the operator respondsto a calling line. The allotter switch used for this Vpurpose is astep-by-step switch consisting of a stepping magnet 210 and a plurality of switching elements'driveii by said magnet through their successive closing` positions. These elements are shown at'209, 9,11, 212. and 2132 .ln theA specific embodiment illustrated,

the allottei' switch 210 serves to allot three diiereiit register senders for use by the operator. The register sender shown in detail iii the drawing' isassigned for use when the allottei' switch is in position 1, while the other twofsenders (not shown) are assigned respectively inopositions 5 and 9 ot Y Further explanation ofthe the allottei. functions oie-the allotter switch Vwill be taken up hereinafter. A Y

It is believed that a clearer understanding may behad oit the principles ot this iiilvention by'givinga dcti'iiled.descrii'ition of the operation of thesystem in the establishlll() lill) ment of a call from one siibscribens line to another. V'llo this end it is assiin'ied thattlie subscriber, whose telephone Vli nates before an operatofs position in .the otiice, wishes-to obtain a connection with Va subscribers line, such asline 540, belonging to the saineV ofce. The subscriber atrsubne termilSll station 100, on removing his receiver :troni the switch hook, closes a circuit trein battery through the lett-hand Winding ot line relay 101, contact 'and outer left-hand armature ot relay 102, over the loop of substation 100, inner lett-hand armature and contact ot relay 102, right-hand Winding o relay 101 to ground. The line relay 101 becomes energized and closes a circuit to `cause the illumination ot the individual line lanip 103 at the operators position. The operator observing the lamp 103 burning knows that the subscriber ot the line to which such lanip is individual Wishes to inale a call. She thereupon seizes the plug 105 ot one ot her idle cord circuits and inserts it in the answering jaclr 104; of the calling line. The insertion ot plug 105 in jack 1041 forces the spring 13bl into engagement with its contact and thereby completes a circuit for the cutotl relay 102. Relay 102 opens the circuit or" the line relay 101 and extinguishes the calling lamp 103. Relay 102 also establishes a circuit troni battery through the Winding ot relay 106, sleeve of plug 105, sleeve o jack 10e, right-hand ari'nature and contact ot relay 102 t0 ground. lRelay 100 attracts its armatures and completes a circuit from battery through the calling line supervisory lainp 108, resistance 13'?, lett-hand armature and contacts ot relay 108 to ground. The lainp 108, however, is shunted out at this tiine by reason ot the tact that the supervisory relay 129 is energized in series with the calling subscribers line, the current for relay 129 being supplied through the left-hand windings of repeating coil 139. The shunt circuit around the laiup 108 inay be traced from battery through the arA ture and contact ot relay 129, resistance 138, resistance 137, lett-hand armature and contact or' relay 100 to ground. Therefore, the calling supervisory lamp 108 remains eX- tinguished.

ils soon as relay 100 energizes when the plug is inserted in the ach, a circuit is cornpleted 'troni battery through the Winding ot relay 100, back contact and niiddle armature ot relay 107, trent contact and oute rightlianl arniature of relay 100, contact and armature of relay 117 to ground. ln parallel to this circuit a circuit is also coinpleted 'from battery through the Winding of relay 110, and thence to ground atlthe contact and armature of relay 117.

l lt will be notedL that relay 118 is also included in series with the i .i allel circuits tot' relays 109 and 110. Relay 118, however, does not energize'since is shunted out by the direct .circuit to ground the contact and armaing or repeat coil 130, iviiding et relay 129, trout coni Y, and inner louer arnicfiture of relay 100, i .ver norinal coni acts of the keys 135, 134. 3 in series, contact and low( e ol; relay 109, ring or pl 'eelt 104, thence 30 through the line 100 and ,tu jack 1011-. ture and upper norir 134i, and l ture and front coni` the upper lett coil 139 to gr l. l't i l also be that the open-tons telephone 130 con nected in .llol to the circuit traced and thereby rece s talking current through the hand uf'indings ot the repeating coil 130. `When rclajf' 110 becones energized, a ci"- cuit is completed from battery through the windings ot relays 113 and 114e iu parallel to ground at the contact and lett-hand armature of rel 110. Relay 114 closes a circuit troni ery through the winding of relay 11? to ground at its lett-hand arniature and contact. Relay 11..7 attracts its armature and l ot tip ot rniosV arniaremoves the snunt from around the Winding ot relay 118. Relay 118, however, cannot energize at this tinie since the current supply through the windings ot relays 100 and 110 in parallel is new shunted aivay troni relay 118 over the circuit leading through the hey 119 and armature and contact ot relay 118. Relay 1111v also coinpletes a circuit "troni ground through the .interruptor 121, :trout contact and innenrightH hand armature of relay 114, Contact and outer right-hand aruiatiu'e ct relay 110, sista-nce 126, lamp 123 to battery and ground. The lamp 123 is intermittently illuminated and extinguished and serves to indicate to the operator that a register sender mechanism is about to be associated with the cord circuit she has taken for use. rlhe lamp 123 Will continue to flash until the associated sender has completed its 'function ot controlling the selective lswitches and is disassociated from the cord circuit.

The relay 113, which energizes in parallel with relay 1141, operates to initiate the movement of the allotted cord i'inder to hunt for the calling cord circuit. The start circuit t r setting the cord finder in operation may be traced from ground through the contact and lett-hand armature ot relay 112, inner right-hand armature and contact of relay 106, innermost armature and back contact of relay 107, outer leltehand armature and contact of relay 113, conductor 241, contact 212 of the allotter switch closed in position 1, conductor 2112, lower left-hand contact 373 (1) of the sender control switch, contact and armature and winding of .the stepping magnet 37 to battery and ground. Magnet becomes euergized, interrupts its own circuit and again becomes deenergized. The construetion of the sender control switch is such that the several contact elements are advanced from one position to another on deenergization of the stepping magnet 372. lt may be well to observe at this point that the stepping switches which con'iprise the several registers shown in the drawing, and also the stepping switch used as a tim. measure device, shown at 210, are also designed to advance ltheir brushes upon deenei'gization of the respective stepping inagets. Consequently', upon the first deenergi- Zation of the stepping magnet 372, the sender control switch is ad.anced out et position 1 and into position ln this position the cord finder is started in operationby means of a. circuit closed from battery through the Winding and armature and Contact of the Steppingmagnet 200, cendrietor 225, lower left-hand contact 804 (2) to ground. The stepping magnet 200 intervrupts its own circuit and advances the brushes 202,- 203, 204C, 205, and 206 from position to position searching i'or the set of terminals individual to the cord circuit shown in Fig. 1. As soon as the test brush 203. of the cord finder reaches the terminal identifying the calling cord, circuit is established from battery through the winding of magnet 200, winding ot relay 201, conductor 229, lett hand contact 365 (2), conductor 228, brush 203, contact and inner lleft-hand armature of relay 113, backcoutactV and outermost armature ot relay 10T toV ground. rlhe stepping magnet 200 and relay'201 have become permanently energized in this circuit and the brushes oitthe cord linder are brought to rest upon the terminals individual to the opcratorls cord cirH cuit for which it was searching. The relay 201, on energizing, completes a circuit from ground through its armature and contact, conductor 231, upper let-hanacontact 373 (2), contact and arma-ture and winding of the stepping magnet 372 to battery and ground. Magnet 372 energizes, interrupts its own circuit anddeenergizes to advance the contacts of the sender control switch to their next position, 3. As the sender control switch leaves position 2 it opens at the left-hand contact 365the original energizing circuit for magnet 200 and relay 201.

"The magnet 200 and relay 201 are maili-V `ot olices and the routing ot calls.

taai-,cil 1 tained energized by means of aV circuit closed through the rightfhand contact 365,A conductor 22T, brush 204, conductor 243,

contact and outermost right-hand armature or relay 114, contact and outer right-Y hand armature ot' relay 112, winding ot relay 12Tv to ground.

Relay 127 Vbecomes energized in series with magnet 200 and relay 201 and closes a circuit troni ground through its outer rig'1 ot relay 111 to battery and ground. Relay 111 locks in a circuit from battery through its wending and contact and inner righthauql armature to ground at the inner righthaiui armature ot relay 113. Relay 111 also vcalling subscribei"s line, and an idle sender mechanism associated with the particular cord circuit utilized by the operator, both oit which operations are responsive automatically to the insertion ot the plug of the cerd circuit in thejack of the calling line. 'l'he operator now challenges the calling line and requests the information concerning the connection desired. The calling subscriber orally communicates to the operator the name Vof Vthe office and also the numberolE the called line in the office with which he wishes a telephone connection. Before proceeding with the duties ot tie operator in recording on the keyboard, the designation communicated to her, a prelimi- Vnary explanation will be given with regard 310, and which are used exclusivelyV :tor designations pertaining to the selection ln a large system, especially where many oliices are concerned, the central oilice sentiers must be adapted to control thelocal VswitchesV in the foce to select outgoing trunks leading to the several distant otlices in the area, as well as trunks leading to switches having access to local lines. The Vlocal selections` namely those taking place at the otlice `of which the calling line appears, are generally taken care of by two selector switches, the district selector and the ollice selector. These switchesin the present disclosure are shown nt-hand armature and contact, windingv Listera the lett-hand portion of Fig. 4. In accordance with the particular type of oliice keyboard illustrated herein, the majority oi the outlying o'liices in the area will be identified by a code number consisting.y for example, ot three characters. lVhen a subscriber requests a connection to any one oit these otiices the operator, knowing the corresponding code, will depress the necessa ry combination ot three ottice keys, one locater in each ot the three rows 305, 310, and 315. By aniY suitable scheme ot' wiring the particular combination ot keys operated will cause the positioning ot all or as many as necessary oi the ottico registers, which ultimately determine the selection ot trunk leading to the outlying` otiice represented by said code. Vilhile many ot the oliices in the system will be identified by codes represented by the three rows ot' ottico keys mentioned, certain otiices will have a single individual key at the operators keyboard. Such offices are those to which the traliic is particularly heavy, and in order to obviate the necessity of depressing a plurality ot keys tor every call the operator is provided with a row oia keys 300, each ot which identities one ot these oiiices.

The second part of the ogerators keyboard consists of 'tour rows ot numerical keys 320, 325,` 330, and 335, and a. row of stat-ions keys 340. On these keys the operator may record the numerical designation ot the called subscribers line and also iden- 'f tity ot the station in case of a party line.

.its will be taken up in detail later on, the record produced by the numerical keys determines the selection ot the called line in the particular otiice to which the connection is extended in accordance with the designation set up on the oliice keyboard.

Returning now to the point where the calling subscriberV communicates the desired designation to the central oliice, the operator upon receiving this information proceeds to make a record thereof on the ottico and numerical keys at her position. it will be assumed that the called subscribers line in the present case termina-tes .in the saine ottico to which the calling subscribers lino belongs and in which the operators position is located. his being the case the district and office switches shown at the lett ot Fig. 4 should be operated to select a trunk routing the .connection to the local switches shown at the right ot Fig. 4 and in Fig, 5 for completing the connection to the called subscriber-s line. Should connection be desired with a distant oiiice it will be seen that the district and otiice switches are then operated to select an outgoing trunk leading to such oliice. ln the present case the key 371 in the row 300 has been assigned tor controlling the district and ofiice switches tol make local connections. As above eX- plained, the remaining otiice' keys in this row may serve to determine the selection of inter office trunks leading to the several ofiices to which said keys are individual. Furthermore, it will be consi lered that the called line is an ordinary line having the numerical designation 8681. Accordingly, the operator depresses the ottico key 371, the numerical keys 393, 394, 395, and 398, and the no stations key 396.

inasmuch as the particular connection being considered is one of the type in which only the local district and otiice selectors need be operated to select a trunk leading to the local group selectors, only the last two ot the o'tce registers 312 and 317 are needed. Therefore, the depression of the othce key 371 will be effective in setting only these two registers ot the ot'rice group together with the class switch shown to the right of Fig. 2. The circuits tor causing the setting of these registers may be traced from battery through the windings and armatures and contacts ot the stepping magnets 311 and 316 ot registers 312 and 317, and from battery through the winding and armature and contact ot the stepping magnet 214- of the class switch, thence by way of the common conductor 233, lower contact 213 of the allotter switch, the upper spring of the row contact 367 to ground. The contact 367 is common to all ot the keys of the row 300 and is arranged to be closed when any one of said keys is depressed. In the parallel circuit above traced, the stepping magnets 311` 316, and 214 are repeatedly operated to advance the registers 312, 317 and the class switch to search tor their respective positions, as determined by the depressed o'liice key 371. .ln order that the first two registers 302 and 307 may not be operated in parallel with other registers, circuits are completed tor maintaining their stepping mag nets permanently energized. The circuit 'for magnet 301 extends' from battery through the winding ot said magnet rela-y 303, contacts 373, brush 329 and its normal position terminal, lower springs ot contact 367 to ground. Similarly a circuit is completed trom battery through the winding of stepping magnet 396, winding of relay 304, con tact 379, brush 3341 and its 'first position contact` lower springs ot contact 367 to ground. llhe stepping magnet 311 of register 312 continues to operate until the brush 339 encounters the terminal 36S. At this time a circuit is completed from battery through the winding of magnet 311, winding of relay 303, contacts 330, brush 339, terminal 368, inner lett-hand contact of key 371 to ground. The magnet 311 becomes permanently energized in this circuit and the brushes 339 and are brought to rest. Likewise, the stepping magnet 316 continues to operate until the brush 334 engages its terminal 369, at

which time a circuit is completed from battery through the winding ot magnet 316,

'the windingl ot' stepping magnet 214. winding` ot relay 215, contacts 363 lower lefthand Contact 219 outer lett-hand contact ot key 371 to ground.

The numerical registers 322., 327, 332, 337 and the stations register 342 are positioned in a similar manner in response to the depression oi the numerical and stations key. The circuits tor stepping magnets 321, 3267 331, 336 and 341 extend trom battery through the ii'indings and armatures and contacts ot these magnets in parallel, contacts 392, right-hand contact ot lzcy 396 to ground. rii`he registers commence to rotate step-by-step in search oit' the positions deter mined by the depressed leys. The first register 322 stops when its brush R46 reaches the terminal connected to the lett-,hand Contact ot key 393, the second register 327 stops when its brush 348 reaches the terminal con` nectcd to the lett-hand contact of relay 394-, the register 332 stops when its brush 1350 engages the terminal connected to the key register 337 stops when its brush 352 reaches :erminal connected to key 35, and the stations register makes a complete revolution and comes to rest in its normal position` at which time brush is making contact with the terminal .connected to the no stations' er lt. rilhe stop circuits oit the .sei7a eral registers include thc windings ot relays` 313, '314, 31S. 319. and l. and the sender control switch contacts S67. 386, 38S). 390,`

and 301. respectively.

As soon as the oii'ice registers 2%'i2 and Pili' and the class switch have been Iriositioned, a circuit is closed as Afollows 'tor driving` the sender control switch out ot position 5i and into position 4: battery. through the winding and armature and contact ot stepping magnet 372, owcr lett-hand contact 382 (3), right-hand armatures and contacts of relays 309 and 308 in series, contacts 216 (4), contact and right-hand armature ot relay 215 to ground. Where the iii-st two registers ot the otiice group 302 and 307 are not to be utilized in the establishment. it becomes necessary li'or 'the sender control switch to skip the positions assigned to these registers. This is accomplished by the class Switch which is now standing in 'position 4. The circuit tor driving the lsender control switch through positions 4 and 5 may be traced fromY battery through the winding and armature and Contact of stepping` magnet 372, contact 366 ,t4-t5), contact 218 (4) to ground.v The. sender control switch is thus driven into position 6 where it renders the register 312 effective to control the transmission ot therrst series Vof impulses to the ldistrict se'- lect-or switch. The register sender is now in condition to transmit the first series ot impulses to cause the group selection at the district switch, depending'upon thc position taken b y the register 3127 rcsponsivcto the depressed otiice key 371.V

The impulse circuit over which series ot impulses are transmitted `trom the register sender to the stepping' magnets ot' the several selector switches was completed at the time the rela-y 127 became energized. rlhis circuit may be traced trom battery. through the right-hand winding oi' the relay 404 at the district selector, back contact and inner left-hand armature ot relay 412. conductor 401, inner left-hand armature and front Contact or" relay 127. conductor 245. brush 206, armature and Contactof stepping relay 207,- brush 205, conductor 2447 front contact and outer lett-hand armature of relay 127, conductor 400, outer leithand armature and back contact of relay 412, left-'hand winding ot' relay 404 to ground. The relay 404 becomes energized and completes a circuit from battery through the winding ot slowto-release relay 405, frontcontact and armature ot relay 404 to ground at-the contact and outer right-hand armature ot relay 412. Provided the time measuring switch 240 is in its normal position as shown in the drawing at the time when the sender control Vswitch reaches, position 6. oras soon thereafter as said time switch reaches its normal position.l a. circuit is closed as follows: battery. through the windig'ot relay252, normal contact 248', brush 247` conductor 267,'lower right-hand contact 377 (6), brush 338 to ground. Relay 252 becomes enerlgized and completes a circuit trom battery through the windingl ot the time measuring switch stepping magnet 2467 the inner armature and front contact of relay 2527to ground. riihe stopping magnet 246 is thus locked in an energizing circuit and provented from advancing the brush 247. Relay 252 also completes a. circuit vfrom ground through its contact and outer.armature7 con-V ductor 235, through the winding of step- Ding magnet 372 to battery and ground. Magnet 372 becomes` energized preparatory to advancing the contacts of the sender control switoh to its next position when its circuit is opened. The next time the constantly rotating interrupter -37 6 is closed a circuit is completed from ground throughY said interrupt/eik, contact (lell y conductor 234, Winding` of relay 249 to battery and ground. llelay 249 becomes energized and a circuit is established from battery throuoh the Winding; ot relay 251. outer left hand armature and Contact et relay 249, baclr contact ai lett-hand a La re oi' relay 250, Contact 248, brush` 24T. conducf'gor es?, ground through brush inpletes a circuit troni battery its Winding` and contact and armature ant. the Winding or relay 250 to the grounded conductor 1slay 2507 however, does not energize at this time since its Winding;- is shunted out by the direct circuit to ground closed through. the outer lett-hand erniature and contact ot relay 249. 0n the next opening` of interrupter B76 and the resultant deenergization of relay 249, rela-y 250 energizes and lock up in series with relay 251.

@n the next closure oli' the interrupter 3.70, relay 249 becomes energized and conipletes a circuit from battery through the vincline of register stepping;` magnet 3117 upper right-hand contact 81'4- (6), conductor 236, inner right-hand armature and front contact of relay 249, contactand rightehand arinature of relay 250, brush 247 to the grounded conductor 23T. Magnet 311 beT cornes energized preparatory to advancing the brushes 339 and 338 Viorviafd to their nextl position When its energizingcircuit is severed. Relay 249 also completes a circuit trom battery through the Winding' of the stepping relay 207, inner lett-h and armature and contact ot relay 249, front contact and left-hand armature ot' relay 250. brush 249 to the grounded conductor 237. Relay 2027 becoines energized and opens the impulse circuit leading to the district selector switch llelay 404 consequently becomes deenergized and closes a circuit for ground through the outer right-hand armature and bac/lr contact of rela-y 412, armature and back Contact of relayr404,varrnature and front Contact of relay 405 Winding of sloW-to-release relay 400, winding; of the primary stepping magnet 407 to battery and groundA Stepping inagnet 407 energizes and advances the brushes 413, 414 and 415 to the level of ter-- ininals. Relay 406, which also energizes, completes a circuit as follows as soon as the brush sha-ft has taken its {irst step to close the ott normal contacts 411 oatttery, through the Windinga ot' relay 410, loyverniost springs of contact 41.1, armature and 'iront Contact oit relay 406. conductor 402` back contact and inner ri `ht-h and armature of relay i12. front contact and outermost armature or' relay 107 to ground. Relay 410 locks up in a circuit from battery through the Winding ot said relay, loiverniost springs oit contact 4H, armature and contact ot the secondary steplllnen the interruptor G again opensl relay 49 leenerznes and breaks the above traced.

r is

or stepping; magnet 3l and steprnet magnet ll. deener-y advances brushes 330 and forlielay 20? also deenergizes the circuit olf the relay 404. llelay racts its orinature and opens the circuit of relay 400 and st-eppi inap;- net but 'the slow-to .lease reliefs 405 l 406 inaintain their armatures attracted during the series ot iinpulses. For each succeeding closure and opening' of the interruptor BTG7 the brushes 339 and 8l S are inoyed forward one step and an impulse is sent to the district switch to operate the primary stepping;` magnet 40T. `illllien the requisite number of impulses hare been sent.y the register 312 reaches its normal position and brush 3138 engages a non-grounded terminal. it this tiine the above traced circuits for relays 252, 255i., and 250 are opened and these relays Jeconie deenergg'ized. Relay 252 opens the circuit oit the topping' magnet 246 which deenergiizes and advances the tinie measuring; switch out oi'f its normal position. llereater each time the interruptor 370 closes and relay 249 attracts its armatures, a circuit is completed itroin battery through the -Win ing ot magnet 246, inner armature and baclt Contact oli relay 252, contact and outer right-hand armature of relay 249 to Vpg-round. Under the control ot relay 249 the tiine nieassuringY switch nialres a complete revolution. rlhe period required 'for this switch to agen reach its normal position is so taken as to insure a time interval Agreat enough lior the selector switches to inalre a maximum trunk hunting` movement. Relay 252. on deenergrizing, also ope* s the circuit oli tbe stepping magnet B72. which becomes {leenera'izerl and advances the sender control switch out or position 6 and into `oosition 7. Since the relay 250 is new deenergized While the time measuring switch is running through its cycle7 the relay 207, and, consequently, the relay 404 rernain energized and unaffected by the intermittent operation ot relay 249.

@n the lapse ot the necessary interval, following the transmission ot the series oi impulses the slo'i -rore.lease rela;v 400 be comes deenernized and a circuit is closed from battery through the inner armature and Contact oit relay 410.` winding oi? 'the secondary steppiur niaejnet 409, normal contects ot rele`` 406 to the grounded con ductor 402. li/lagnet 409 energizcs and advances the brushes or the selector switch onto the first set of terminals in the selected level. The energization of the stepping magnet 409 opens the holding circuit ol relay 410, which becomes decnergiz/,ed and in turn severs the operating circuit of said stepping magnet. Stepping magnet 409 therefore releases its armature. ln case the first trunk, upon the terminals of which the brushes 413, 414, and 415 are nonv standing, .is busy, a ground yiiotential uill exist on the test terminal 418 thercot. Relay 410 theretore becornes energized as soon as the stepping magnet 409 deenergizes in a circuitt'rom battery through the winding otl said relay, lou'ei'most springs ot contact 411. armature and contact ot magnet 409.l back contact and inner right-hand armature ot' relay 412, brush 415 to the grounded test terminal 41S. lt will be noted that a parallel circuit is completed through 'the Winding of relay 412 to thc grounded conductor 402. Relay 412, however. remains inert since it is shunted out directly by the busy ground potential on test terminals 413. Relay 410 again closes the circuit ot stepping magnet 409 which operates to advance brushes to the next set of tern'iinals. When the test brush 415 reachesl the test terminal 413 of the tirst idle trunk, relaxY 412 is included in series with relay 410. Relay 412 thereupon attracts its armatures but duc to its comparatively high resistance, relay 410 cannot energize. The stepping magnet409 ceases to operate and the brushes are brought to rest in engagement with the terminals ot the idle trunk. rllhe operation ot relay 412 opens the circuit ot' relay 404 which becomes deenergized and in turn opens the energizing circuit of relay 405. helay 412 also extends the grounded conductor 402 by way of the front contact and inner right-hand armaturewot said relay through to the test terminal 418 to render the selected trunk busy to other district switches.

VAs soon as the time measuring switch 240 reaches its normal position terminal 248, the circuit otrelay 252 is closed by Way ot the conductor 237. loiver lett-hand contact 377 (7'), brush 343 of register 317 to ground. Relay 252 closes a holding circuit for the stepping magnet 246 and also a holdin g circuit ior the stepping magnet 312 of the sender control switch. rl`he next time relay 249 becomes energized, relay 251 is operated in the circuitabove traced to terA minal 248, brush 247, and thence to ground over conductor 237. Relay 251 prepares a circuit for relay 250 which becomes energized and locked up as soon as relay 249 releases its armatures. The next closure of interrupter 376 and the resultant energization ot relay 249 establishes a circuit trom battery throughv the Winding ot the register stepping magnet 316, upper left-hand Contact 374t7), conductor 236, inner right-hand armature of relay 250, and thence to ground over the conductor 237. Magnet 316 attracts it-s armature preparatory to advancing the brushes and 343 to their next position terminals. Relay 249 also completes a circuit vfrom battery through the Winding ot the stepping relay 20T, inner lett-hand. armature and contact oi' relay 249, tront contact and lett-hand armature orp relay 250 to the grounded conductor 237.

'At the time the relay 412 operated7 the impulse circuit including conductors 244, and was extended by Way oit the letthand armatures and back contacts o? relay 448 to the windings ot the relay 419 at the oliire selector switch. Relay 419 therefore becomes energized in series with the stepping relay 207 aty the sender. Relay 419, on attractin its armatures. completed a circuit :from battery through the winding of slov` to release relay 420, contact and righth'and armature ot relay'419 to the grounded test terminal 418. Relay 420 becomes energized and locks tin a circuit from battery through its Winding and right-hand armature and contact to the grounded test terminal 418; lith-en, therefore, the stepping relay 20T iirst attracts its armatureto open the impulse c-ircuit, relay 419 releases its armatures and a circuit is established from ground through the outer right-hand armature and contact ot relay 419, left-hand ar- .nature and tront contact of relay 420, Windi ng ot' sloWfto-release; relay 421, Winding ot stepping magnet 422 to battery and ground. rlhe primary stepping magnet 422 operates to advance the brushes 427, 428,'and 429 opposite the tirstV level of terminals. Relay 421. yivhich also energizes, completes a circuit as tolloivs after the first primary step of the brush shaft: battery, through the Winding otrelay 425,1oiver springs ot the ott' normal Contact 426, armature and front contact ot relay 421 to the grounded test terminal 418. Relay 425 becomes energized and closes 'a locking circuit for itselt from battery through the Winding of said relay,

vlower springs of contact 426, armature and contact of the secondary stepping magnet 424, contactand outer Yarmature of relay 425 to ground at the contact and outer righthand armature of relay 448. When relay 249 and consequently relay 207 become de- 'energized the rircuit ot relay 419 is completed. which operates to sever the energizing circuit of the stepping magnet 422. This magnet becomes deenergized and releases itsarmatures in readiness to advance the brushes through another step. For each succeeding` closure ot the interrupter 376 the register 317 is advanced through one position and the office selector' switch is opera-V ted to move its brushes Opposite the next level. After the impulses have all been sent and the register 317 reaches'its normal posi tion the brush 343 engages an open terminal. Consequently, relays 252, 251 and 250 release their armatures. ln the manner above described, relay 252 causes the time measuring switch to commence rotating and also opens the holding circuit of the stepping vmagnet 372, whereby the sende-r control switch moves out of position 7 and into position 8.

lVhile the time measuring switch is passing through its cycle, relay 207 and relay 419 remain permanently energized. Consequently, relay 421 deenergizes after an in terval and a circuit is established from battery through the inner armature and contact of relay 425, winding of the secondary step-- ping magnet 424, normal contactsotf relay 421 to the grounded test terminal 418. Stepping magnet 424 energizes and advances the brushes 427, 428, and 429 into engagement with the rst set of terminals in the chosen group. The energization of magnet 424 causes the opening of the circuit of relay 425. Relay 425 releases its armatures and in turn opens the operating circuit of magnet 424. lf at the time magnet 424 becomes deenergized, the first trunk in the group is busy, a ground potential exists on terminal 4 32 thereof and a circuit is closed for the reenergization of relay 425. This circuit may be traced from battery through the winding of said relay, lower springs of off normal contact 426, armature and contact of magnet 424, back contact and inner righthand armature of relay 428, test brush 429 to the grounded test terminal 432. Relay 448, it will be observed, is included in parallel with this circuit. Relay 448, however, does not energize so long as it is shunted out by direct connections to ground at the busy test terminals 432. Relay 425, on energizing completes a circuit for the stepping magnet 424, which again operates to advance the brushes to the next set of terminals. This procedure continues until an idle trunk is located, at which time the relay 448 is included directly in series with relay 425. Relay 448 becomes energized but due to the high resistance thereof, relay 425 remains inert. Relay 448, at its left-hand armatures, opens the energizing circuit of relay 419. Relay 448, at its front contact and inner right-hand armature, extends the grounded test conductor through to the test brush 429 'and test terminal 432 to render the selected trunk busy to other selector switches. The impulse circuit. is now extended over the left-hand armatures and front contacts of relay 448, the left-hand armatures and back contacts of relay 440 to the windings of relay 433 and this relay becomes energized. Relay 433 closes a circuit from b'attery through the winding or slow to release relay 434, contact and right-hand armature of relay 433 through the grounded test terminal 432. Relay 434 operates and locks up in a circuit from battery through its winding and right-hand 'armature and contact and thence to ground over the test termina 432.

Following the operation of the oilice switch, it will be recalled that the sender control switch advanced out of position 7 and into position 8. In this position the sender control switch waits until the operator has recorded the numerical designation on her keyboard. Provided the numerical keys have already been operated and the registers corresponding thereto have been adjusted to their proper positions, a circuit is completed -for advancing the sender control switch. This circuit may be traced from ground through the right-hand armatures and contacts of relays 323, 319,318, 314, and 313 in series,lower right-hand contact 382 (8), contact and armature and winding of stepping magnet 372 to battery and ground. Stepping magnet 372 interrupts its own circuit and advances the sender control switch out of position 8 and into position 9. In position 9 of the sender control switch all the operated keys are restored to normal. For this purpose the key release magnets 354, 355, 356, 357, 358, 359, 360, 361 and 362 each of which controls a row of keys, are provided for releasing the depressed keys. A circuit 'for energizing these magnets may be traced from battery through said magnets in parallel andthence to ground over the upper contacts 397 closed in position 9. As soon as the depressed keys have been released the hereinbelore traced circuits, through the successive stepping magnets of the registers, are opened and these magnets, together with the relays in series therewith, became deenergized. A circuit is now established from ground through the left-hand armatures and contacts of relays 323, 319, 318, 314, 313, 309, 308, 304, and 303 in series, left-hand armature and contact of relay 215, lowei1iglit hand contact 373 (9), contact and armature and winding of magnet 372 to battery and ground. Magnet 37 2 operates to advance the sender control switch out of position 9 and into position 10.

l/Vith the sender control switch in position 10 the next idle register sender is allotted for use by the operator. The stepping magnet 210 of the allotter switch is energized in a circuit from battery through the winding and contact and armature of said magnet, right-hand contact 211 (1), lower righthand contact 364 (10) to ground. Magnet 210 energizes and advances the allotter switch to its next stopping position, namely position 4. ln case the next register sender in order is idle at this time, relay 208 is inoperative and the allotter switch is immediately advanced into position 5 by means of a circuit from battery through the winding and armature and contact of magnet 210, left-hand contact 211 (4), to ground at the ffrcgister sender unit. lthe register senders be busy simultaneously, VVa circuit is completed .trom battery through the winding of relay 203, contact 209,: closed back contact and outer armature Vof relay 208. In this position the next register sender is assigned for use and the incoming start wire 241V isextended over the lower lright-'hand contact 212, closed in position 5,

in either positions 4, 3, or 12, conductor 222,

thence in series over two different contacts similar to the contact 370V and contact 297 to ground.

other Ssender units not shown. For the third `sender unit there will be provided another contact similar to the contact 370. Under these conditions the relay 208 is energized and the allotter switch is prevented from advancing into either of its allotting positions, Relay 208 also places a ground Vpotential on each ofthe conductors 220 and 221, which results in the energization of all the key release magnets. Therefore, the operator is unable to record a. designation on her f keyboard until a registcrsender hasibecoine idle and is allotted forfuse.

With the sender contiol switch in position 10 a circuit is closed for relay 252'as soon as the time measure switch reaches its normalV position, from battery through the winding of said relay, contact 248, brush 247, conductor 237, upper lett-hand contact 335 (10), brush 345 to ground. Relay 252, in the manner explained, closes a locking` cir- --cuit for magnet 246 and also for magnet 372. rllhe lirstenergization and deenergiza-V tion oiirelay 249 result, as explained` in the operation otrelays 251 and 250. On.y the neXt attraction of the armatures otrelay 249, a circuit is closed from battery through the winding of magnet 321 ot the first numerical register 322, lower lett-hand Y contact 384 (10), conductor 236, inner righthand armature and contact of relay 249, conh tact and 4right-hand armature of relay 250,

and thence to the grounded conductor 237. Magnet 321 becomes energized and prepares to advance its brushes 345 and 346 forward one step. Relay 249 also completes thel above traced circuit for the stepping relay 207. W'hen relay 207 4operates it opens the impulse circuit tofpermit relay 433 at the selector switch to release. Relay 433 establishes a circuit from ground through the outer right-hand armature and Contact or The contact 37 0, which is shown Vin dotted lilies, is individual to one ofthe marcia erative relation with the first level of ter minals. wWhen the brush shaft has taken its first step the off normal contact 447 is released and a circuit is closed from battery through the winding of relay 439, lower Y springs of contact 447, armature and front contact ot'relay 435 tothe grounded test terminal 432. Relay 439 attracts its armatures and locks up in a circuit from battery through the winding'ot said relay, lower springs of contact 447 armature andcontact of the1 secondary stepping; magnet 438, contact and outer armatureof relay 439 to ground at the contact andouter right-hand armature otrelay440. The -interrupter 376, on opening, releases .the relay 249, which in turnV releases the relay 207 and relay 433 thereby becomes energized. The circuit of magnetv436 is now opened and its armatures are withdrawn Vto makeready for advancing thebrush shaft another step. At each-fol! lowingyoperation ofrelay 249' the register 322 is stepped forward and thebrush shaft of the selector switch `is moved into operative'relation with anotherlevel of terminals. lVhen the register brush 345 finally reaches its normal position, ground isremoved from conductor 237 and relays 252, 251 and 250 retract their armatures. Relay 252 permits the release Voi magnets 246 and 372.Y Consequently. the time measure switch starts out to complete another cycle while the sender control switch advances from posi-V tion'10 Aand into `position 11.`

During the travel of thetime measure switch through its cycle, relay 432 at the selector switch remains permanently ener-l gized and after. an interval ,the slow to release relay 435 retracts its armature. A circuit is thereupon completed from` battery through the inner armature and contact of relay 439, winding oi: magnet 438, closed contacts of relay k435 to the grounded test terminal 432.` The secondary stepping magnet 438.*moves the brushesl into engagement with the first set of terminals in the-selected level. Magnet 4334 also. severs the holding circuit ofrelay 439 which becomesdeeneigized and in turn opens the circuit of mag,-` net 433.V ln the manner already explained, the relay439 isi-again energized in case the test brush 443 engages-abusy test terminalY 446 and thestepping Lmagnet 438 operates to i advance the brushes on to the next set of terminals. This :automatic trunk hunting.V operation continues until an idle trunk is found, at which time relay 439 remains energized andthe-relay 440 becomes operated in series with relay 439. Relay 440, at its left-hand armatures, opens the circuit of relay 433 and at its inner right-hand armature extends the grounded third conductor through to the test brush 443 and test terminal 446. The impulse circuit is thereupon extended to the next selector switch over the left-hand armatures and front contacts of relay 440, lett-hand armaturesand back contacts of relay 507, and the windings oi relay 500. Relay 500 becomes operated in the impulse circuit and attracts its armature. A circuit is then closed from battery through the winding ot the slow-to-release relay 501, contact and right-hand armature of relay 500 to the grounded test terminal 446. Relay 501 energizes and locks up in a circuit from battery through its winding and right-hand armature and contact, and thence to ground, as described.

lThe time measure switch 240, on returning to its normal position, establishes once more the circuit for relay 252, which now leads by way of conductor 237, upper righthand contact 385 (11) to ground over brush 347 ot register 327. Relay 252 closes the holding circuits for magnets 246 and 372. The energization or relay 249 now completes a circuit for relay 251 which extends, as eX- plained, over the grounded conductor 237, and thereafter the deenergization or' relay 249 permits relay 250 to energize and lock,

up in series with relay 251. The next time relay 249 operates it extends the grounded conductor 237 over its Contact and inner left-hand armature to the winding of relay 207, and also over its contact and inner right-hand armature, conductor 236, lower right-hand contact 384 (11), winding ot stepping magnet 326 to battery and ground. The magnet 326 operates and relay 207 attracts its armature to open the impulse circuit. When the impulse circuit is opened relayv 500 at the selector switch becomes deenergized and completes a circuit from ground through the outer right-hand armature and contact or" relai' 507, left-hand armature and contact of relay 500, left-hand armature and front contact of relay 501, winding of the slow7 to rele-ase relay 502, winding of the primary stepping magnet 503 to battery and ground. Magnet 503 and relay 502 operate in this circuit. Magnet 503 moves the brushes 509, 510, and 511 oli' the selector switch into operative relation with the first group of terminals in the terminal banlr. Relay 502 closes a circuit as soon as the ofi' normal contact 508 is released at the vfirst step or' the brush shaft. This circuit may be traced from battery through the winding of relay 506, lower springs of contact 508, armature and front contact of relay 502 to the grounded test terminal 446. Relay 506 actuates and locks up in a circuit from battery through the winding of said relay, lower springs ot oil' normal contact 508, armature and contact of stepping magnet 505, contact and outer armature of relay 506, contact and outer right-hand armature of relay 507 to ground. The next opening of interruptor 37 6 permits the release or relay 249, and consequently the deencrgization ot the stepping relay 207 and the stepping magnet 326. Magnet 326, on deencrgizing, releases the brushes 347 and 348 to their nent position terminals. Relay 207 closes the impulse circuit and relay 500 energizing in response thereto opens the operating circuit including relay 502 and magnet 503. Stepping magnet 503 deenergizes but relay 502, being slow-to-release in character, remains operated during the transmission of' impulses. For each succeeding operation ot relay 249 in response to the closure and opening of interrupter 376, the stepping magnet 326 is energized and deenergized to advance the register brushes while stepping relay 207 operates to control the circuit of relay 500. In response to the operation of relay 500, stepping magnet 503 advances the brushes of selector switch from position to position. As the register reaches its normal position, brush 347 disengages the grounded terminals and relays 252, 251, and 250 become dee/nergized. Relay 252 opens the holding circuit ot the magnet 246 so that the time measure switch commences to operate under the control of interruptor 376 to complete a rotation. The stepping magnet 372, on having its energizing circuit opened, releases to advance the sender control switch into position 12.

During the time the switch 240 is completing its cycle the relay 500 remains energized. After the necessary interval relay 502 releases its armature and a circuit is established from battery through the inner armature and Contact or' relay 506, winding of the stepping magnet 505, closed contacts of relay 502 to the grounded test terminal 446. Stepping magnet 505 operates to advance the brushes 509, 510, and 511 into engagement with the terminals of the irst trunk in the selected group. Magnet 505 also opens the circuit of relay 506 which becomes deenergized and in turn opens the circuit of said magnet. It the first trunk in the group is busy its test terminal 514 will be identified by the presence of a ground potential and relay 506 becomesenergized in a circuit including the lower springs of contact 503, armature land contact of magnet 505, back contact and inner right-hand armature of relay 507, brush 511 to the grounded terminal 514. The relay 506 again prepares a circuit for the stepping magnet 505 which operates to advance the brushes onto the neXt set of terminals. W'hen the first idle trunk is encountered, relay 506 remains deenergized and the relay 507 is now operated since the registers of the sender.

husyto other group selector switches. Relay 507 also completes the impulse circuit for controlling the connector switch. This circuit may be traced from battery through the right-hand winding of relay 515, contact Wand outermost left-hand armature of relay 517, terminal 513, brush 510, front contact and inner. lett-hand armature of relay 507, thence over the lower side of the line through the armature and contact of relay 207l at the sender and returning over the upper side of the line tothe outer left-hand armature and front contact of relay 507, brush 509, terminal 512, make before break contact at the outer lett-hand armature of relay 518, through the left-hand winding of relay 515 to battery andV ground. VRelay 515 becomes energized and closes a circuit from battery through the winding of relay 516, Contact and inner right-hand armature of' relay 515, contact and middle left-hand armature of relay 517 to the grounded third conductor 541. Relay 516 operates and locks up in a circuit from battery through its winding and left hand armature and contact, contact and middle left-hand armature of relay 517 to the grounded conductor 541.

The connection has thus been extended to the connector switch and the impulse circuit prepared for controlling the tens and units selective movements of this switch in accordance with the setting of the last two vWhen the time measure switch 240 again reaches its normal position, relay 252 becomes energized in a cir- V.cuit as hereinbefore traced to the conductor 237, thence over the lower r1ght-hand contact 385 (12) to ground at the brush 349 of register 332. Relay 252, as explained, comi pletes circuits for magnets 246 and 372. Re-

lay 2'49 energizes in response to the inter- Vrupte'r 376 and relay 251 operates and later relay 250 1s energized 1n series therewith.`

At the first energization of relay 249, following the operation of relay 250, the grounded conductor 237 is extended by way of the contact and inner right-hand armature of relay 249, conductor 236, lower right-hand contact 383 (12), winding of magnet 331 to battery and ground. Also the grounded conductor 237 is extended by way of the contact and inner lett-hand armature of relay 249, winding of relay 207 to battery and ground. Magnet 336 becomes energized for the purpose hereinbefore explained and relay 207 attracts its armature to open the im- 515 at the connector switch. Relay 515,V

upon deenergizing, establishes a circuit from ground through the innermost left-hand armature and back contact ot' relay 517, outerright-hand armature' and back contact of relay 515, inner right-hand armature and front contact of relay 516, normally closed contacts 542 and 543, winding ot slow to release relay 534, winding otprimary stepping magnet 522 to battery and ground. T he stepping magnet 522 operates to advance the brushes 528, 529, and' 530 into operative relation with the first group of terminals.

lielay 534 also becomes energized in series with magnet Y522. The next opening of interrupter 376 causes the deenergization of relay 207 and stepping magnet 331. Magnet 331 releases the brushes 349 and 350 to their next position terminals, and relay 207 recloses the energizing circuit of relay 515.

Relay 515 opens'the abovev traced circuit for relay 5,34 and magnet 522. Magnet 5'22becomes decnergized but relay 534, being slowto-release, does not retract its armatures. Un the 'next opening of the impulse circuit, relay 515 becomes deenergized and a circuit is closed from ground through the innermost armature and back contact of relay 517, outer right-hand armature and back contact of relay 515, inner right-hand armature and front contact of relay 516, contacts 542 and 533, armature and front vcontact and winding of relay 534, winding of stepping magnet 522 to battery and ground.Y The contacts 542'and 543 were openedV and contacts 542 and 533'were closed upon the first primary step of the brush shaft, these contacts being` so arranged that the closure of the latter pair takes place prior tothe opening'of the first mentioned contacts. .The stepping magnet 522 again operates to advance the brushes of the connector switch to another y group of line terminals. After theregister 332 has been completely restored to itsnol-, mal position, during which time the brushes of the connector switch are advanced' from one group of terminals to another, the brush 349 disengages the last grounded terminal and removes ground from the conductor 237. In response tothe removal of this ground, relays 252, 251, and 250 retract theirarma-Y tures. Again the time'measure switch 2.40 commences to rotate and the sender control switch advances Vthrough another position, coming to rest'in position 13. 'Following the completion of the impulse series, relay 515 remains energized Yand after an interval the slow-tofrelease Vrelay 534 retracts its armature.

vWhen the time measure switch 240 reaches its normal position relay 252 is energized once more in a circuit traceable by way of conductor 237, lower right-hand Y contact 386 (13) brush 351 of the units register 337 Lasse 1a to ground. ln the manner well understood, relays 250, 251, and 2&9 operate under the control of the interrupter 376 to establish and disestahlish in succession the operating circuits ot the stepping relay 207 and the stepping magnet 336 o' the units register 337, and also to close holding circuits for the stepping magnets 246 and 372 o1 the time measure switch and sender control switch, respectively. For each imculse transmitted, relay 515 releases its armatures whereupon a circuit is closed :trom ground through the innermost left-hand armature and hack contact oit relay 517, outer right-hand armature and back Contact oit relay 515, inner righthand armature and front contact ot relay 516, contacts 512 and 538, armature and hach contact of relay 534, winding of slow to release relay 525, winding of the secondary stepping magnet 524 to batterT and ground. Relay 525 and magnet 524 operate in this circuit. Magnet 524em serves to advance the brushes 528, 529, and 530 from one set or' terminals in the selected group to another. lllhen the last units impulse has heen transmitted, the register brush 351 disengages the grounded terminals and relays 252, 251, and 250 become deenergized to in turn release the stepping magnets, 24:6 and 372. rlhe time measure switch 240 commences to rotate in the manner hereinoetore Y described.l No useful function, however, is

andringing operations, a description will he giren of the manner in which the register sender is released and restored to its normal condition.

Since no stations impulses are to loe sent, the sender control switch should be immediately moved out of position 14. rllhis-is accomplished hy means of a circuit from ybattery through the winding and armature and contact oit stepping magnet 872, lower contactv 366 (14), contact 217 ot the into position 15.

class switch to ground. Magnet B72 operates' to advance the sender control switch A circuit is now established from battery through the winding and armature and contact of magnet 372 to ground at the upper right-hand contact 382 By means of this circuit the sender control switch is stepped from posi- Ation 15 through position 18 and into its normal posltion 1.

lllhen the senderl control switch moves out Vof position 14- the locking circuit through magnet 200 and relay 201 is opened at the Y right-h Vinain'taining the relays Y ne,

ad contact 365. Magnet 200 is now fg Zed in a circuit Ltr in battery through its winding and armature and contact to ground at hrush 202 et the cord finder switch. The magnet 20() interrupts its own circuit and steps the brushes 203, 20e, 205, and 20G from position to position until they are completely restored to normal. At this time the operating circuit of magnet 200 is opened.V at brush 202 and the cord finder switch comes to rest.

it the same time the holding circuit of magnet 200 and relay 201 was opened, the relay 127, included in said circuit, also hecame deenergized. Relay 127 completes a circuit from Ibattery through resistance 128,

inner right-hand armature and hach contact of said relay, contact and inner lefthand armature oil relay 111, front contact and middle armature or relay 107, front contact and outer right-hand armature of ref lay 106, winding or relay 118 to ground. llc-lay 118 energizes in this circuit and opens the circuit which up to this time has been 110 and 109 energized. Relay 109, upon deenergiaing, autornaticallyV disconnects the operators telephone set from telephonie relation with the calling subscrihe1"s line and extends the conductors olt the calling line through to the lett-hand windings et the repeating coil 139. lielay 110, on releasing its armatures, opens the holding circuits of relays 113 and 1111-. Relay 1123 opens the locking circuit ot' relay 111 and this relay 1oecomes deenergized. Relay 11d, at its lett-hand armature, opens the circuit or' relay 117. Relay 114, at its innermost right-hand armature and front contact, opens the circuit through interrupter 121 which has been causing the lamp 123 to flash. rlhe lamp 123 is now illuminated steadily in a circuit from battery tlirough said lamp, resistance 126, outer right-hand armature and contact ol relay innermost right-hand armature and hac-l; contact ot relay 11/1 to ground at the contact and outermost right-hand armature ol? relay 115. lt will he noted that relay 115 heroines energized over conductor at the time the otl'normai contact L111 nlosed on the first step ot the district selector switch. She lamp 123 hy discontinuing its flashing signal and luirning steadily indicates to the operator that all selections have heen completed and the register sender disassociated iron the cord circuit.

heturning new to the point where the connector switch is'positioned on the ter- `s of the called suhscrihes line in reto the transmission ot the units i i or impulses, a consideration will loe given to the testing and signaling operations which follow automatically. Assuming the called suhscrihers line 5a() to he idle when units selection is completed., a circuit .is established as'follows as soon as relay 525 releases .its armatures:battery, through the lwinhding of the* cut-.off relay 527 of the called subscribers line, test .brush 539, left- .hand armature and back .contact ofrelay 525, contact andoutermost left-hand arma- .t-ure ofrelay 526, left-hand winding of rel"lay 517, front contact Vand outer righthand .closed .toY hold. said. relay `energized battery, through the right-hand `winding and contact v.and .innermost righthand armature of relay 517 .to ground over .the conductor 541. .Relay 517 opensthe holding circuit ofrelay V516 and this latter relayretracts its-armatures. .Relay 517 furthermore completes the ringing circuit over which signaling current is applied to the called `subscribeus line. VThe ringing circuitinay'be traced fromthe source ofcurrent 520 to the left-hand wind- .ing'of relay 518, back contact and inner` lefthand armature of said relay, contact and outermost.right-hand .armature of .relay 517, ,outer right-hand armature and contact of relay `526, Abrush 529, thence over vthe loop of the called subscribers line, brush 528, back contact andinner rightr-hand.armature of relay 526 fand middle armature and Contact .ofirelay A527,7outer left-hand armature and vback contact ofrelay v518 toground. ARelay 518 does not operate in the circuit traced due Lto the high resistance of theringer-Inagnet at the substation. Y

When .the calledsubscriber answers by re Uinoving his .receiver from the switch hook,

the .resistance 4of the ringer magnet is excluded .and :sufficient current flows through .theleft-hand .winding of relay 518 to cause the actuation thereof. Relay 518. immediately locks .up in a circuit from battery through .itsf'right-hand windingLand right-hand armatureand contact,.normal contact of relay 519, .terminal 512,-'brush 509, .front Vcontact and outer. left-hand .armature of relay .507, thence over the front contacts and .outer .left-hand armatures of the relays 4:40, 4L-18, and `512 `at lthe preceding group selector aswitches, conductor400, outer left-hand armature andback contact of relay 127 normal .contact of the relay 110, upper right-hand winding of repeating coil 139 to ground. .The .relay.518 being energized and the called sub- 1scriber7s'receiver being off the switch hook, Y.

.lay/'1107, at its outermost.arinatureand front .iaiclosed "circuit .is established through the left-hand armatures and :frontrcon'tacts of relay 518 over the talking .conductors 519. Relay 519at its armature and makabe- `fore-break Vcontact providesa Vsubstitute holding circuit for the .right-hand winding of relay 51,8 through the grounded conductor 541 independent of Vthe first energizing circuit `which leads overthe 'upper`talling conductor to ground at the repeating coil 139.

'.Relay 131 in the operators cord *circuit .also energizes. in series with-relay 521 and the called subscribers substation. This relay completes. a circuitfroin Abatterythrough `its .armatureand contact, normal .contacts at the inner left-hand armature of .relay .116, winding or" .relay 116, innermost right-.hand

armature and .Contact .of relay 115 to ground. Relay 116 immediately VVoperates and V'locks v.u p .in `a circuit :from batterythrough.- its. inner left-hand .armature .and front contact f and windingV to ground at the .innermost Yright- :hand armature of relay115.V Relay.1.16.com pletcs -a fcircuit :from .battery through "the lamp 122, resistance .125.130 ground at the i inner right-hand armature `and front contact.`

.of relay.117. IThe lainp122,.however,.does Y I not illuminate .since it .is :shunted 4out' `by a direct circuitfrom batteryto-.ground which Amay .be traced .-as follows: battery,-through the `armature fand-.contact .of relay 1131, contact and Vouteiwleftfhand aiinature .of relay .116, resistances12t1and 125, innerrightf-hand armature and front cont-actof relay `116-t0 ground. Relay116, onenergizing, also opens `the above traced :circuit 'through -the lamp 123. ylfhe retirement-of the signal ..123 -acvises the operator that the. callcdsubscriber `has responded. .A completeV talking circuit Y is-now.established-andthecalling and called subscribers may converse with eachother.

At the end ofthe .conversationthe .calling 'and .called subscribers by replacing their receivers on the switch hooks cause the deener- A gization .of thesupervisory relays129 and 131 Vin the operatorsv cord circuit. .lRelay129 .removes the .shunt from :around .fthe .lamp .1108 .and this *lamp .becomes .illuminated to .notify the` operator that they callingparty has hung uphis receiver. 'Similarly,'the.relay- .131 opens the shunt. aroundV la1np.l122 which lights toadvise the .operator that Vthecalled subscriber has hung upihis receiver. In responselto these signals the operatorseizes the plug105f and withdraws itfi'romthe-jaclr 'of the calling. line. .Theremovalof theplug from thevjack openslthe circuit .of relay,106 which Vdeenergizes and in .turn opens the holding circuitforrelay l 107, permitting this latter relay 'to 4release .its armatures. Re-l Y position.

Contact, removes ground potential from the conductor 402. rllhis opens the parallel circuits of relays 412, 448, 440, and 507 which have been holding these relays energized.

The resulting deenergization or" relay 412 causesthe closure of a circuit from battery through the winding of release magnet 408, middle springs of o normal' contact 411, back contact and armature orx rela-y 405, back contact and armature of relay 404 to ground at the Contact and outer right-hand armature of relay 412. rlhe release magnet 408 operates in this'circuit and restores the brush shaft of the district selector to its normal In the restored position of, the brush shaft the off normal contact 411 opens its several springs and thefrelease magnet 408 becomes denergized. In a manner identical to that described release circuits are also closed for the release magnets 428, 437, and

V504 of the three succeeding switches and these switches are restored to their normal [positions It will also be noted that the removal of the ground potential from con ductor 402 also permitted the release of relays 420, 434, and 501.

When the called `subscriber hung up his receiver relay 521 became deenergized and permitted the release or relay 519. Since at this time the upper talking conductor is opened by reason of the preceding switches having been released, the release o relay 519 does not reclose vthe original holding circuit o the relay 518. When ground poten- Vtial is removed from the conductor 541 due to the deenergization of relay 107 and the release of the intermediate switches, the

Vholding' circuit o relay 517 is opened and this relay retracts its armatures to establish the release circuit. The latter circuit may be traced from battery through the winding of release magnet 528, springs 544 and 545, back contact and inner rightehand ar- "mature of relay 516, back contact and outer right-hand armature of relay 515 to ground at the back contact Vand the innermost lefthand armatureof relay 517. lt will be observed that relay 516 immediately deenergizes as soon as ground potential is removed from `conductor 541. Release magnet 523 operates in the well-known manner to return the brush shaft of the connector lswitch to its normal position.

The occasion frequently arises that the operator wishes to recall the called subscriber moving the switch hook to cause the intermittent illumination of the supervisory from battery through the windings of relays 109 and 110 in parallel, through the contacts Vof said key, front contact and outer righthand armature of relay 108 to ground at the contact and armature of relay 117. The operation or relay 109 again places the operators telephone set 130 in talking relation with the calling subscribers line, while relays 109 and 110 become locked up through the key 119, as hereinbefore explained. The called subscriber having hung up his receiver prior to this time, relay 521 is deen ergized and relay 518 is now held energized in a circuit through its right-hand winding and right-hand armature and contact and the inake-beore-break contact of relay 519 to ground as previously traced over the upper talking conductor, through the normal contact at the inner right-hand armature of relay 110, upper right-hand winding of repeating coil 139 to ground. When relay 110 becomes energized in response to the operation of the operators listening-in key A140, the circuit for relay 518 is modiiied to the extent that it now leads over the upper talking conductor 400, contact and outer right-hand armature of relay 110, key 120, inner Vright-hand armature and front contact of relay 110, through the upper right-hand winding of repeating coil 139 to ground. This circuit is thus made dependent upon the condition of the ope-rators key 120. To rering the called subscribers line the operator merely depresses the key 120 to temporarily open the above traced circuit for relay 518. Relay 518 bccomes'deenergized and at its left-hand armatures completes the ringing circuit for applying ringing current to the called subscribers line. lhen the called subscriber answers, the circuits are converted in the manner already explained and further conversation may take place between the subscribers.

l The operator having succeeded in recalling the called subscriber now retires from the connection by depressing her listeningout key 119. The operation of this key opens the locking circuits or relays 110 and 109 and the resultant operations take place as described.

t will next be considered that the called subscriber-s line 540 is busy at the time the brushes of the connector switch are set on the terminals thereof. The line being busy, a ground potential exists on the test terminal and the following circuit is immediately closed assoon as the last impulse has been transmitted: battery, through the winding of relay 516, make before break contact and left-hand armature of relay 525, which relay remains energized for an interval following

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