US1464084A - Telephone-exchange system - Google Patents

Description

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Aug., 7, 1923.

A. E. LUNDELL ET AL TELEPHONE EXCHANGE SYSTEM Filed June 9, 1920 10 Sheets-Sheet l Aug. 7, QEE., M464@ A. E. LUNBDELL ET AL TELEPHONEv EXCHANGE SYSTEM Filed June 9, 1920 ILO Sheets-Sheet 2 Q QN 1J) J@ Aug., 7, 11923.

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A. E. LUNDELL ET AL.

TELEPHONE- EXCHANGE SYSTEM Aug. 7, w23.

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A. E. LUNDELL ET AIL TELEPHONE EXCHANGE SYSTEM Filed June 9. 1920 10 Sheets-Sheet 6 /rn/emors: A/ben E. Lande/l Edgar H. C70/K @f Aug.. 7, E923..

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TELEPHONE EXCHANGE SYSTEM Filed June 9 1920 A. E. LUNDELL ET AL TELEPHONE EXCHANGE SYSTEM'v l Filed June 9. 1920 10 Sheets-Sheet 10 /hx/em fors /ben E Lande/L Edgar H. C/m/K Patented 7, H9323,

muren stares tentent cornice ALBEN E. LUNDEL'L, OF CHlICAG-O, JULLINJIS, AND EDGAR EL CLARK, 0F BJICHMND mild), NEW YRK, .LSSEGNORS TO WIESTERN' ELECTRC COMPANY, IENCORPORTED, 0F NEW YORK, 'El'. Y., .d COBJPRATIEON UJF NEW YUEK.

TELElPlBmNlE-EXCEMGE SYSTEEM'.

Application tiled June 9,

T o all fwhom 'it may concern:

Be it lmown that we, Armin lE. llannnnnr. and Encan lill. (linnn, citizens of the United States, residing at Chicago, in the county of Coolr` and State of llllinois, and at Richmond Hill, in the county oi Queens and State of New York, respectively, have invented certain new and useful improvements in 'llelephone-Exchange Systems, of which the tolio lowing is a lull, clear, concise and exact descrlption.,

rlFhis invention relates to telephone exchange systems in which connecting oper ators are employed for extending connections, with indicating mechanisms at such operators positions to identity the designatlons or' desired lines.

lin systems where certain oces are equipped with mechanical switching apparatns, whereas other oces employ manual operators tor establishing coections, it is ,-ounddesirable that the manualoperators loe given the information required for them to extend or complete coections incoming from the mechanical oiltce without the necessity of communicating orally with the calling subscriber or with other operators. 'llo this end, each. operators position, in the manual oce, is provided with call indicator mechanism, including a set of numberindicating devices, which is operated automatically under the control ot registering mechanism in the' mechanical oce to inform the manual connecting operator oit the number and character of the required connection. llt is customary, in arrangements of this character, to provide each trunlr circuit incoming to an operators position from the distant mechanical omce with a signal 4o lamp, the illumination of which advises the operator that a call is awaiting her attention on the corresponding trunlr. At her convenience she associatesr the calling trunk with the common indicating mechanism at her position, and thereupon the wanted designation is set up and displayed betere the operator, who proceeds to complete the connection.

Where no attempt is made to secure a uniiaao. serial no. aantal.

formity in the distribution of calls to the several operators in an oce of this character, it may frequently occur during busy hours of the'day, that an excessive number of calls simultaneously appear on the trunks at any given operators position, while at the two positions adjacent thereto only a comparatively few calls are awaiting attention. in order that the completion of calls shall not be unduly delayed on this account, provision is made whereby the adjacent operator on either side of a home operators position may assist the home operator by attending to some of the calls at her position.

Accordingly, it is the object of this invention to provide, in a system of the foregoing character where operators positions are each equipped with a group of trunks and an indicating mechanism, means whereby one operator may cause to be set up, on the indicating mechanism at her position, the designation of calls appearing on trunks at other Operatoris positions.

A feature of the invention/relates to an arrangement whereby the currentimpulses incoming over the trunk circuit at a home operators position, which normally serve to record the desired designation on the indicating mechanism at such position, may be directed to an adjacent position for the purpose of recording the designation on the indicating mechanism at said adjacent position.

Another feature relates to the provision of two assignment keys for each trunk circuit at an Operators position; one of which, when operated, associates the corresponding trunlr` with the indicating mechanism at said position and causes the incoming impulses to set such mechanism in accordance with the designation concerned; the other of which keys, when operated associates said trunk with the indicating mechanism at a diderent operators position and causes the incoming impulses to record the designation on the mechanism at said latter position.

Still another feature relates to the provision of a signal individual to an incoming trunlr which operates in one distinctive trated in Fig. 11, disclose so much of a tele` phone system which embodies the invention, as is necessary to an understanding thereof.

Fig. 1 shows the incoming end of an interoiiice trunk circuit at a mechanical oiiice and the details of a district selector switch in which said trunk line terminates. Fig. 2 shows in detail the circuits of an olice selector switch in the mechanical oilice.

Fig. 3 shows a trunk finder switch, com- `mon to a plurality of incoming trunk circuits, for associating an idle register sender with a desired trunk.

Fig. 4 shows a sender for controlling the operation of the selective switches, comprising a circuit changing sequence switch and a oup of counting relays.

ig. 5 illustrates a plurality o sets oi keys at an operators position, and a series of corresponding registers arranged to be positioned under the control of said keys for determining the selective operations involved in the extension of a connection.

Fig. 6 shows a switch and associated circuits for transmitting series of code impulses, according to the variable settings of the registers, to operate a call-indicator mechanism at a distant olice.

Fig. 7 shows in detail a trunk circuit incoming from the mechanical oiice to a manyual operators position in a distant oilice.

Fig. 8 shows a call-indicating mechanism at the manual operators position arranged to be associated with any of the trunk circuits at such position and operated in response to the code impulses sent over a calling trunk lfrom the mechanical oiflce.

Fig. 9 shows the .selecting relays and numerical lamps of the call-indicator for visually informing the manual operator of the designation of a called line.

Fig. 10 illustrates diagrammatically a trunk circuit similar to that shown in F ig.

' 7, incoming from the mechanical office to an operators position adjacent to the position at which the first mentioned "trunk ap ears. Below the horizontal broken line in th1s figure there is illustrated the call-indicator mechanism at` the adjacent operators position which is similar in all respects to the one shownin detail in Figs. 8 and 9.

Fig. 11 shows how the iguresof the drawing are to be arranged to connect the circuits of the several figures.4

. General description of system and apparatus.

In the establishment of a connection in the system, disclosed, three different oilices are to be considered; a calling manual oflice,

-where the call first originates; the tandem mechanical oiiice, through which the connection is extended by means of automatic the operator therein communicates with the* operator in the mechanical oiiice by means of an order wire and requests the assignment of an idle trunk. The operator at the mechanical office assigns an idle trunk, such as trunk 100, 101, and depresses the individual assignment key 108. The depression of key 108 initiates the operation of the trunk finder shown in Fig. 3, which associates the7 register 4sender shown in F igs. 4, 5 and 6, with the assigned trunk. The operator in the mechanical oiiice having` been verbally informed of the name of the desired oiiice and the number of the called line insuch oiiice, proceeds to set up the designation on the keys at her position. The selective operations of the district and oiiice switches, which jointly serve to select an outgoing trunk to `any one of. a plurality of distant oiices, are controlled by the settings of the four registers 500, 510, 520 and 530. Each of the various combinations of settings that these registers may take, determines the selection o a group of trunks leading to a y particular distant oiiice. .For convenience,

therefore, a single oilice key is provided to ll0l required number of ofice selections. In ad- Y dition to the oliice4 keys, the operators position is equipped with four sets of numerical keys, ten keys in each set, for. setting the .numerical registers 540, 550, 560 and 570.

After the operator has depressed the proper combination of oice and numerical keys the district and oiiice selectors are operated and the connection extended over a trunk, suchy as 700, 701, to an operators position in the desired manual iiiee. The

loperator in the.terminating oice is informed that a call is awaiting her attention, by the illumination of a lamp individual to the incense trunk circuit. As soon as the operator has completed the extension of such calls as may have previously been directed to her position, she attends to the call appearing o n the trunk 700, 701, by depressing the ind1- vidual assignment key. The depression of this key operates to associate the call-indicator mechanism at her position with the calling trunk circuit. Code impulses are then sent over the trunk in accordance with the settings of the numerical registers oi' the mechanical otlice to select the pro er combination of numerical lamps. rllhe i umination of the indicator lamps at the operators position informs her of the number of the called line and the connection is completed by inserting the terminating plug of the trunk circuit in the proper jack.

lt may happen that due to the simultaneous appearance of a large number of calls at a given position, the operator is unable to attend to all the calls with the necessary dispatch. According to the principles oit this invention, the adjacent operator on either side is able to assist the home operator whenever she becomes overtaxed in her duties, by attending to some of the calls at the home position. For this purpose, each of the trunks at a position is provided with a team assignment key. 'llhe adjacent operator, observing the presence of a larger number oit calls at the home position than the home operator can conveniently handle, reaches across and depresses the team assignment key ot a callingtrunk. 'llhe depression ot 'the team key `,serves to associate the Calling trunk at the home position with the callindicator mechanism at the adjacent operators position. The incoming code impulses are, therefore, directed to the indicator mechanism at the adjacent or helping-out operators positionand the designation of the desired line displayed on the numerical lamps at such adjacent position. yll`he adjacent operator then seizes the plug ot the calling trunk circuit at the home operators position and inserts it in the jack of the called line. As will be more fully explained hereinafter, supervision of a call thus completed by an adjacent operator, remains under the care of the home operator in the same manner as calls normally attended to by the home operator.

contacts .contained in each of such figures. ln Figz, the contacts contained within the spaces set 0E by the vertical broken lines, are controlled respectively by the correspondingly located sequence switches.

Detailed desme'ptonf-dz'sposz'ton of @all by the home operator.

the connection is extended, is comparatively unoccupied and able toattend to the call without the vassistance of the adjacent operator. rJlhe call having been originated in a distant manual oHice and the trunk 100, 101 having been assigned for use, the operator in the mechanical office depresses the assignment key 108.- A circuit is then completed from ground through the contacts of key 108, right-hand contact 109 (1),. winding of sequence switch magnet 110, to battery and ground. Sequence switch 110 moves out of its normal position 1 into position 3. ln position 3 of sequence switch 110 a' circuit is established from battery, through the winding of the trunk tinder sequence switch 310, right-hand contact 317 (1) conductor 329, lower` right-hand contact 113 V(3), upper right-hand contact 113 (3), back contact and letthand armature of rela 111, upper left-hand contact 121 (2 to 1 lower right-hand Contact 121 (1 to 12), to ground.F 'lhe trunk finder sequence switch 310 leaves its normal position and advances into position 2. iin position 2 of sequence switch 310, a circuit is completed trom battery, through the winding of the up-drive power magnet 320, contact 31d (2), back contact and left-hand armature of relay 311, to ground. Magnet 320 energizes and the brush shaft 312 of the trunk finder is moved upward to selectL the set of terminals individual to the trunk 100, 101. When the test/brush 307 of the trunk finder reaches the terminal 302, a circuit is closed from battery, through the winding of relay 311, left-hand contact 328 (2), brush 307. terminal 302, conductor 139, lower contact 122 (3), upper contact 122 (2 to 3),back contact and outer right-hand armature of relay 111, upper lefohand contact 119 (2 to 11), lower left-hand contact 119 (2 to t), to ground. Relay 311 attracts its armatures and opens the circuit of the 11p-drive power magnet 320, causing the brushes of the trunk finder to stop in engagement with the desired set of terminals. Relay 311 locks up in a circuit n from battery through the winding of said relay, right-hand contact 328 (2 to 17), right-hand armature and contact of relay Cdl L depresses No. 4- key 311, brush 309, terminal 304, conductor 141, lower left-hand contact 114 (2% to 16), upper right-hand contact 114 (2 to 129;) to ground. Relay 311 also completes a circuit from ground through its left-hand armature and front contact, right-hand contact 315 (2), winding of sequence switch 310, to battery and ground. Sequence switch 310 moves out of position 2 and into position 6. In position 6 of sequence switch 310, a circuit is closed from ground, through contacts 313 (6), brush 308, terminal 303, conductor \145, left-hand contact 115 (3), right-hand winding of relay 111, to battery and ground. Relay 111 energizes and completes a circuit from battery, through 'the winding of sequence switch 110, lower letthand contact 112 (3), upper {right-hand contact 112 (2 to 12), front contact and left-,hand armature of relay 111, upper lefthand contact 121 (2 to 17), lower righthand contact 121 (1 to 12) to ground. Sequence switch 110 advances from position 3 into position 5, opening the circuit of relay 111, which thereby deenergizes.

An idle register senderl is now associated with the calling trunk circuit 100, 101.

The operator, having been informed over the order wire of the wanted designation, depresses the key 580, which determines the selection of the desired oiiice. Furthermore, she sets up on her keyboard the numerical designation of the-called line in that oice. 'Ifheseveral oiiice and numerical keys at the operators position are arranged to be retained in their actuated position by means of locking magnets `503, 513, 523, 533, 544, 554, 564 and 574i Assuming that the number of the wanted line is 4432, the operator 543 in the thousands row, No. 4 key 553 in the hundreds row,

.No.3 key 563 in the tens row and No. 2

keyL` 573 in the units row. Assuming the code pertaining to olice key 580 to be 1223, the contacts 'of this key are wired to contactsi of the four oilice registers 500, 510, 520 and 530, closed respectively in positions 1, 2, 2 and "3.

As soon as the trunk finder sequence switch 310 reaches \position 5, parallel circuits are completed thrugh'the windings of the registers 500, 510,` 520, 530, 540, 550,

560 and 570, back contacts and right-hand armatures of the` respective stop relays 501, 511, 521, 531, 541, 551, 561, and 571, to the common conductor 582, contact 326 (5 to-6),

to ground. These registers are all ener-l gized in the circuits traced and commence to rotate. When register 500 reaches position 1, a circuit is closed from battery through the winding of relay 501, contact 502 (1), left-hand contacts of key 580, to ground. When register- 510 reaches position 2, a circuit is closed from battery through the windingof relay 511, contact 51.2, (2), left-hand contacts of key 580, to

ground. In position 2 of register 5,20, a circuit is closed from batltery through the winding of relay 521, contact 522 (2), righthand contacts of key 580, to ground. In position 3 of register 530, a circuit is completed from battery, through the winding of relay 531, contact 532 (3), right-hand con` tacts of key, 580, to ground. Relays 501, 511, 521,' and 531 energize in the circuits traced and open the operating circuits of the four oliice registers, causing them to stop in their respective positions. When the numerical registers 540, 550, 560 and 570 reach positions 4, 4, 3, and 2 respectively, similar circuits are closed through contacts 542, 552, 562 and 572, for the stop relays 541, 551, 561 and 571, and in a similar manner, the operation of these relays opens the circuits of the numerical registers, causing them to cease to rotate. With all the stop relays' energized a series circuit is closed from ground, through the front contacts and left-hand armatures of said relays, conductor 583, lower right-hand contact 316 (6), winding of sequence switch 310, to battery and ground. Sequence switch 310 advances from position 6 into position 10. As sequence switch 310 passes through positions 7 and 8 a circuit is closed from ground contact 330, (7 to 8), conductor 584,- through the windings of the holding magnets 503, 513, 523, etc. in parallel, to battery and ground. These magnets energize and release the depressed keys of the operators keyboard. The registers do not restore, but remain in the position last used. In position 10 of sequence switch 310, a circuit is closed from Ibattery, through the winding of the sender sequence swltch 410,"r lower right-hand contact 407 (1), contact 331 (10), to ground. The sender sequence switch moves from its normal position into position 4.

The office and numerical designations are now recorded on the registers of the sender and the selective operation of the district and oiiice switches may be proceeded with. Accordingly, the fundamental circuit for controlling the brush selection of .fthe district switch is established as follows: battery, through the right-,hand winding of relay 111, lower left-hand contact 118 (5),

-lower right-hand Vcontact 118 (5 to 8), conllF nuancer,

left-hand armature of relay 111, upper lefthand contact 121 (2 to 17), lower ri ht-hand contact 121 (1 to 12), to ground. equence switch 110 advances into position 6. Relay 111 remains energized in position 6 ot sequence switch 110 by means of a circuit from battery, through the right-hand winding, contact and inner right-hand armature of said relay, upmr lett-hand Contact 118 (3 to 10), lower right-hand contact 118 (5 to 8), and thence to ground over the fundamental circuit as described. 1n position 6 of sequence switch 110 a circuit is closed from battery through the winding of the updrive magnet 127, lower right-hand contact 112 (6), upper right-hand contact 112 (2 to 12), front contact and left-hand armatureot rela 111, upper lett-hand contact 121 (2 to 17 lower right-hand contact 121 (1 to,.12), to ground. The power magnet 127 energizes and causes the upward movement et the brush shaft 129. For each brush tripping position passed over by the brush shaft 129, the auxiliary brush 130 makes engagement with a metallic segment of the,

brush selecting commutator 132 and completes a circuit rom battery, through the right-hand winding, contact and inner right-hand armature of relay 111, upper lett-hand contact 118 (3 tol 10), lower righthand contact 123 (5% to 6), commutator 132, brush 130 to ground. The closure ot this circuit maintains the energization of relay 111 and at the same time shunts out the stepping relay 400 in the fundamental circuit.

17V hen stepping relay 400 first energizes in series with relay 111 it completes a circuit from ground through its contant and armature, lower contact 402 (4), conductor 585, Contact 504 of register 500 closed in position 1, conductor 505, and thence to conductor 426 (Fig. 4) armature and back oontact of the No.' 1 counting relay 422, winding ot No. 1 counting relay 423, to battery and ground. Relay 423 energizes and closes a circuit -from battery through the windings of relay 423 and 422, contact and armature of relay 423, contact 404 (4) to ground. Relay 422, however, dcesgnotl energize at this time since it is shunted out by the direct circuit to ground closed at the armature and contact of the stepping relay 400. .As soon as the brush 130 encounters the lirst metallic segment of the brush-selecting commutator, theA stepping relay 400 deenergizes, and removing the shunt around relay 422, permits this ,relay to energize in series with relay 423. @n the next energization of the-stepping relay 400, as brush 130 reaches an insulated segment, the stepping circuit, closed at the armature and contact of relay 400, is

extended by way of conductors 505 and 426,

" armature and front contact of relay 422,

right-hand armatureA and contact of relay 420, ding of relay 421, to battery and und. Relay 421 energizes and completes a circuit trom battery through the windings of relays 421 and 420 in series, contact and armature ot relay 421, contact 404 (4), to ground. As soon as stepping relay 400 is again shortcircuited the shunt is removed `from around the winding of relay 420 and this relay energizes in series with relay 421. The operation ot the 0' counting relay 420 opens the fundamental circuit at its outer left-hand armature and closes at its inner lett-hand armature a circuit including upper right-hand contact 407 (4), for driving the sender sequence switch 410 out of position 4 and into position 6. Sequence switch 410, passing from position 4 toposition 6, opens at its contact 404, the locking circuit of the counting relays, permitting them to release. As soon following the energization ot' the 0 counting relay 420, as the brush 130 reaches the net insulating segment, relay 111 is deenergized and opens the circuit of the 11p-drive power magnet 127, terminating the movement ot the brush shaft. Relay 111 also completes a circuit from battery through the winding of sequence switch magnet 110, upper left-hand contact 113 (6), upper righthand contact 113 6), back contact and lett-hand armature or relay 111, upper left-hand contact 121 (2te 17), lower righthand contact 121 (1 to 12), to ground. Se-

uence switch 110 advances into position 7. circuit is now closed from battery, through the winding of vthe brush-tripping magnet 128, upper and lower right-hand contacts 121, to nd. rllhe magnet 128 energizes and prepares tor the tripping of the selected set of brushes on the next upward movement of the brush shaft.

The fundamental circuit is again established from battery through the right-hand winding of relay 111, lower left-hand contact 118 (7), lower right-hand contact 118 (5 to 8) and thence as above traced, through the winding of the stepping relay 400, to fr und at contact 403 closed in position 6. elay 111 becomes energized and completes a circuit from battery, through the winding of sequence switch ma et 110, lower letthand contact 112 (7), upper right-hand contact 112 (2 to 12), tirent contact and letthand armature ot relay 111, to ground at contact 121. Sequence switch 110 advances into position 8 while relay 111 remains locked up over its right-hand winding in the manner explained. Relay 111 a circuit trom battery,- through the vending of the up-drive power magnet 127, lower right-hand Contact 112 hand contact 112 (2 to 12), front contact and left-hand armature of relay 111 to ground at contact 121. Magnet 127 energizes and causes the brushIl shaft 129 to more, upward in the group selecting move- (8), upper rightl ment. Eacli time the brush 130 engages a metallic segment of the group-selecting commutator 133, a circuit is closed from battery through the right-hand winding, con- 'tact and inner right-hand armature of relay When relay 400 energizes in Series w1th` relay 111 a circuit is closed from ou'nd through the contact and armature o' relay 400, upper con-tact 402, (6), conductor 586 contact 514 of register 510 closed in position 2, conductor 515, and thence to conductor 427 (Fig. 4), armature and back contact of relay 424, winding of relay 425, to bat tery and ground. Relay 425 energizes and prepares a circuit for relay 424, which latter relay becomes energized as soon as the stepping relay 400 is shunted out by the groupselecting commutator of the switch. For each group of terminals passed over by the brushes 142, 143 and 144, the step; ping relay 400 is operated and a pair of counting relays energize and lock up. When the 0 counting relay 420 is finally energized, the fundamental circuit is opened and a circuit closed including the upper righthand contact 407 (6) for driving the sender sequence swi-tch into position 10. In passing from position 6 to position 10, contact 404 of sequence switch 410 is opened to permit the releaseof the energized counting relays.

As'soon after-'the opening of the fundamental circuit Aby the 0 countingrelay 420, asthe brush 130 engages an insulating segment of the commutator 133, relay 111 is deenergized.- 'Relay 111 opens the circuit of power magnet 127, causing the switch to come to rest in operative relation to the desired group of terminals. Relay 111 also closes acircuit from battery through the winding of sequence switch ma et 110, upper left-hand contact 113 (8), upper righthand contact 113 (8), back contact and lefthand armature of relay 111, to ground at contact 121. Sequence switch 110 moves out of position 8 and into position 9.

In position 9 of sequence switch 110, re-

lay 111 is immediately energized by means of a circuit from battery, through the righthand windinoF of said relay, lower left-hand contact 118 9 to 9%) upper left-hand `contact 123 (9 to 9%), to ground.V Relay 111 completes a circuit from battery through the winding of sequence switch 110, lower lefthand contact 112 (9), upper right-hand contact 112 (2 to 12), front contact and lefthand armature of relay 111, to ground at contact 121, driving sequence switch 110 into posltion 10. Provided the first trunk in" the selected group, on the terminals of which the '10 and into position 11.

brushes 142, 143 and 144 are now standing, is busy, relay 111 remains energized in the following circuit: battery, through the lefthand winding of said relay, contact 120 (9 to 10, front contact and outer right-hand 12), front contact and left-hand armature ofrelay 111, to ground at contact 121. Magnet 127 is energized and brush shaft 129 moves upward in .the trunk-hunting operation. When the test brush 144 encounters an idle test terminal, the holding circuit of relay 111 is opened and this relay releases itsl armatures tovopen the circuit of the power magnet 127. Relay 111 also closes a circuit from battery, through the winding of sequence' switch magnet 110, upper left-hand contact 113 (10), upperrlght-hand vcontact 113 (10), back contact and left-hand armature of relay 111, to ground at contact 121. Sequence switch 110 moves out of position 110, on reaching position 10%, c oses its lower left-hand contact 119 to sup ly a busy ground potential 'over test brusii 144 to the test terminal 136 of the selected trunk.

In position 11 of sequence switch 110 the fundamental circ-uit is extended through to the office selector shown in Fig. 2 for controlling brush-selection at this switch. The fundamental circuit may be traced from battery through the right-hand winding of relay 211, lower left-hand contact 203 (l), left-hand contact 208 (1 to 4), conductor 200, terminal 134, brush 142, lower left-hand Se uence switch` contact 123 (11), lower right-hand contact 118, (11), conductor 137, terminal 300, brush 305, upper contact 324 (10), winding of stepping relay 400, contact and outer lethand armature of relay 420, upper righthand Contact 403 (10) lower right-hand contact 403 (10), upper contact 323 (10), brush 306, terminal 301, conductor 138, lower contact 125 (11), brush 143, terminal 135, conductor 201, contact 230 (1 to 4), to ound. Relays 211 and 400 become energize in this circuit. Relay 211 closes a circuit from battery, through the winding of sequence switch magnet 210, lower left-handcontact 204 (1) .front contact and left-hand armature of r^e lay 211, to ground. Sequence Switch 210 moves from position 1 into position 2. Rea

aaeaoea from battery, through the right-hand winding, front contact and inner right-hand armature, outer right-hand armature and contact of said relay, lower right-hand contact 203'(1 to 4), and thence to ground as described. Relay 211 closes a circuit from battery through the Winding of the up-drive power magnet 213, right-hand contacts 205 (2), front contact and left-hand armature of relay 211, to ground. Magnet 213 energizes and causes the upward movement of the brush shaft 215 in the brush-selecting operation.y F or each brush-tripping position of the shaft 215, brush 218' engages a metallic segment of the brush-selecting commutator 219. A circuit is thereby closed from battery, through the right-hand winding, front contact and inner right-hand armature of relay 211, outer right-hand armature and front contact of said relay, lower right-hand contact 203 (1 to 4), upper righthand contact 203 (1% to 2), commutator 219, brush 218, to ground. This circuit maintains the energization of relay 211 and causes the stepping relay 400 in the fundamental circuit to be shunted.

`When relay 400 first energizes in series with relay 211 a circuit is closed from ground, throu h the contact and armature of relay 400, ower contact 401 (10), conductor 587, Contact 524 of register 520 closedl in position 2, conductor 525, and thence to conductor 427 (Fig. 4), armature and back contact of the No. 2 counting relay 424, winding of relay 425, to battery and ground. Relay 425` becomes energized and prepares a locking circuit for itself in series with relay 424. )When brush 218 encounters theA first metallic segment of commutator 219, the stepping relay 400 is shunted and relay 424 becomes energized. The stepping circuit closed at the armature and contact of relay 400 is now extended over the armature and front Contact of relay 424 to the next counting relay '423. When the proper number of brush-tripping positions have been passed over by the brush 218, the 0' counting relay 420 is energized to open the fundamental circuit.A Relay 420 also closes a circuit including its inner left-hand armature and contact and upper right-hand contact 407 (10) to drive sequence switch 410 into position V12. As soon after the fundamental circuit is opened by the 0 counting relay, as brush 218 moves on to an insulating segment of contator 21,9, relay 211- becomes deenergized. This closes a circuit from battery, through the winding of sequence switch magnet 210, lower right-hand contact 204 (2), back contact and left-hand armature of relay 211 to ground. Sequence switch 210 e advances from position 2 into position 3. Tn position 3 of sequence switch 210, a circuit is closed from battery through the winding of the brush-tripping magnet 214, lower left-hand contact 200 (3 to 7), to ground. Magnet 214 energizes preparatory to tripping the selected set of brushes on the next upward movement of the shaft 215.

With sequence switch 210 in position 3 and sequence switch 410 in positionV 12 the fundamental circuit is again closed in the manner described for controlling the groupselecting operation of the ofoe switch. Bes lay 211, upon energizing, closes a circuit from battery, through the winding of sequence switch ma et 210, lower left-hand contact 204 (3), front contact and left-hand armature of relay 211, to ground. Sequence switch 210 advances into position 4, and relay 211 remains energized in the circuit leading through its right-hand armatures and the lower right-hand contact 203. Relay 211 completes a circuit from battery through the winding of the 11p-drive magnet 213, right-hand contacts 205 (4), to ground at the front contact and left-hand armature of relay 211. The brush shaft 215 is moved upward and for each group of trunlr terminals traversed the brush 218 engages a metallic segment of the group-selecting coinmutator 220. A. circuit is thereby closed from battery, through the right-hand winding, front contact and inner right-hand armature of relay 211, outer right-hand armature and contact of relay 211, lower righthand contact 203 (1 to 4), upper left-hand contact 203 (3;3; to 4), commutator 220, brush 218, to ground. This circuit holds the relay 211 energized and causes the shunting of the stepping relay 400 in the fundamental circuit.

When relay 400 cnergizes in series with relay 211, with sequence switch 410 in position 12, a circuit is closed from ground, through the contact and armature of relay 400, upper contact 401 (12), conductor 588, contact 534 of register 530 closed in position 3, conductor 535, and thence to conductor 428 (Fig. 4), armature and back contact of the No. 3 counting relay 429, winding of the No. 3 relay 430, to battery and ground. Relay 430 attracts its l,armature and prepares a locking circuit for itself, in series with the winding of relay 429. As the brush 218 encounters the first segnient of the commutator 220, relay 400 lis released to permit the energization of relay 429. @n the next energization of stepping relay 400, the stepping circuit is extended by way of conductor 428, armature and front contact of relay 429, armature and back contact of relay 424, winding of relay 425, to battery and ground. Tn asimilar manner the No. 2 counting relays and each following pair of counting relays are energized and locked up in response to the operation of stepping relay 400. `When the 0 counting relay 420 is hnally energized,

the fundamental circuit is opened and a circuit, including up er right-hand Contact 407 (12), is closed switch 410 out of position 12 and into position 14. As soon following the opening of the fundamental circuit at the sender, as brush 218 engages an insulating segment of commutator 220, the holding circuit of relay 211 is opened. Relay 211 releases its armatures and opens the circuit ofV the updrive power magnet 213, bringing the brushes 225,226 and 227 to rest in operative relation to the selected group of outgoing trunks. Relay 211 also completes a circuit from battery, through the winding of sequence switch magnet 210, lower righthand contact 204 (4), backI contact' and left-hand armature 'of relay 211, to ground.

Sequence switch 210 advances into position 5.

In position 5 of sequence switch 210, relay 211 is immediately energized in a circuit from battery through the left-hand winding of said relay, upper left-hand contact 229 (5 to 7 lower left-hand contact 229 (5), to ground. Relay 211 closes a circuit rom battery, through the winding ot sequence switch magnet 210, lower lefthand contact 204 (5), front contact and left-hand armature of relay 211, to ground, for driving sequence switch 210 out of position 5 and into position 6. Relay 211 remains energized in position 6 of the sequence switch, provided the irst trunk in the selected groupy` is busy at this time. The holding circuitfor relay 211 may be traced from battery through-fthe righthand winding, front contact and inner right-hand armature of said relay, outer right-hand armature and contact of relay 211, upper left-hand contact 207 (5 to 18), upper rightfJ hand contact 207 (5 to 6i), test brush 227, test terminal 224, and thence to a multiple of test terminal 224 at some other switch, brush 227 of such other switch, to ground at )the upper right-hand contact 206\(6 to 8i completes a circuit from battery through thev winding of the up-drive power magnet 213,A right-hand contact 205 (6), front contact and left-hand armature of re1ay 211, to ground. Switch shaft 215 is advanced upward in lthe l trunk-hunting movement. When an idle trunk is reached the holding circuit of relay 211 is opened, since no A=ground is found on the test terminal 224.

The following substitute circuit, however, is maintained closed to prevent the immediate 'l release of relay 211. VBattery, through the left-hand Winding of said relay, upper lefthand contact 229 (5 to 7), upper right-` hand contact 229 (5% to 6), centering cornmutator 221, brush 216, to ground.` This circuit is closed until'the brushes 225, 226y and l227 are accurately centered on the terfor driving sequence Relay 211 by remaining energized,

minals of the idlev trunk, at which time brush 216 engages an insulating segment of commutator 221. Relay 211 thereupon releases and opens the circuit of the updrive power magnet 213. Relay 211 also closes a circuit from battery, through the winding of sequence switch ma et 210, lower right-hand contact 204 (6), back con tact and left-hand armature of relay 211 to ground. Sequence switch 210 advances from position 6 into position 7. On rea-ching position 6%, sequence switch 210 closes its upper right-hand Contact 206 to apply a busy ground potential to the test ter' minal 224 of the selected trunk. Relay 211 is again immediately energized by means ofl a circuit from battery, through its lefthand winding, upper left-hand contact 229 (5\ to 7 lower left-hand contact 229 (7 toJ ground. Relay 211 completes a circuit from battery through the winding of the sequence switch magnet 210, lower left-hand contact 204 (7 front contact and left-hand armature of relay 211 to ground. Se uence switch 210 advances into position 8. elay 211 remains energized in positionl 8 of sequence switch 210 by means of a circuit from battery through the right-hand winding, front contact and inner. right-hand armature .of relay 211, outer right-hand armature and contact of said relay, upper left-hand contact 207 (5 to 18), lower left-hand contact 207 (7 toy 18), conductor 202, terminal 136, brush 144, upper righthand contact 119 (9 to 1611), lower left-hand contact119 (10L to 18), to ground. The district and oiiice switches having been positioned in the manner described a trunk circuit 700, 701 is selected leading to a mtnual operators position in the distant o ce When the sender sequence switch 410- reaches position 14, after the completion of oilice group selection, a circuit is closed from ground, 'through contact 408 (14), upper eft-hand contact 316 (10), winding of sequence switch magnet 310, to battery and ground. ySequence switch 310 moves out of position 10 and into position 11. A circuit 1s now completed vfrom battery through the back contact and inner lower armature 0* relay 725, (Fig. 7 conductor 731, righthand winding of` relay 713, winding of relay incense 1451i), lower contact 323 (11), brush 306, terminal 301, conductor 138, lower contact 125 (11), brush 143, terminal 135, conductor 201, upper contacts 209 (8), brush 226, terminal 223, conductor 701, inner armature and back contact of relay 708., inner armature and back contact of relay 717, outer normal contact ot' relay 716, left-hand winding of relay 713, to ground. Relay 713, being marginal, does not energize in series with resistance 419. Relays 714 and 412, however, energize in the circuit traced. Relay 714 closes a circuit trom ground, through its` armature and contact, winding of relay 715, to battery and ground. Assuming that plug 726 of the trunk circuit has not been removed from the jaclr by the operator after the termination of a prior call, relay 710 will be energized by means of a circuit to be hereinafter described. Hence when relay 715 operates, it closes a circuit for itself from battery, through the winding and contact and inner left-hand armature of said relay, front contact and outer upper armature of relay 710,

back contact and inner left-hand armatureV ot relay 712, to ground. Relay 715, at its right-hand armature and contact, shunts out the relay 714, permitting the latter relay to release. Relay 715 also closes a circuit from battery, through the assignment lamp 711, outer right-hand armature and back contact of relay 7 05, right-hand armature and contact of relay 704, contact and outer left-hand armature of relay 715, to ground. The illumination of lamp 711 informs the operator that a call is waiting on the corresponding trunk.

1t, however, the plug 726 is not inserted in a line jack at the time the trunk 700, 701 is seized, relay 710 is deenergized and relay 715, inding no locking circuit, again releases as soon as relay 714 has been shunted out. Referring to Rig. 4, relay 412 which energized in series with relay 714 completes a circuit trom battery, through the winding of relay 411, armature and contact of relay 412 to ground. Relay 414 is energized at the-same time by means of a circuit from battery, contact 415 (14 to 16), winding of said relay, armature and contact of relay 412, to ground. Relay 411, at its lowerinost armature and front Contact, closes a circuit including contact 409 (14), for driving the sender sequence switch 410 out of position 14 and into position 16. As the sequence switch 410 reaches position 14%, the circuit above-traced through the right-hand winding ot marginal relay 713, over the upper or tip side of the line to lower contact 324', is now extended by way of lower contact 406 (14% to 156), innermost armature and front contact of relay 411, winding of relay 412, contact and armature of relay 414, tront contact and middle armature of relay 411, lower contact 405 (145, to 16), lower contact 323 (11), and thence over the ring side ot the line to ground at the left-hand winding of marginal relay 713. 1t will be observed that the resistance 419 has been excluded from this latter circuit. Relay 713, therefore, becomes energized and completes a circuit from battery, through the winding of relay 712, to ground at the contact and armature of relay 713. Relay 712 closes a circuit in shunt of relay 714 as `follows: battery, back contact and inner lower armature of relay 725, conductor 731, righthand winding of relay 713, contact and outer left-hand armature of relay 712, inner normal contact of relay 716, and thence over the tip side of the line and returning as described, to ground at the letthand winding of relay 713. Relays 714 and 715, therefore, remain deenergized. Relay 712 completes a circuit from battery through the assignment lamp 711, outer right-hand armature and back contact of relay 705, right-hand armature and Contact ot relay 704, Contact and inner upper armature of relay 710, contact and inner right-hand armature of relay 712, to ground. rilhe lamp 711 is illuminated and the operator, observing the same, knows that a call is awaiting her attention.

At her convenience the operator responds to the call by depressing the home assignment key 703 which -is individual to the trunk 700, 701. Thekdepression ot key 703 operates to associate the trunk with the call indicator mechanism at the home operatorie position. A circuit is closed from battery through the winding of relay 81.18, conductor 732, contact and outer lower armature ot ref lay 710, right-hand winding of relay 7 05, contact of key 703, conductor 733, armature and contact of relay 823, back contact and ri hthand armature of relay 821, to ground. elay 705 energizes and loclrs up in a circuit from battery through the winding oit relay 818, conductor 732, contact and outer lower armature of relay 710, windings ot relay 705, in series, contact and lett-hand armature of said relay to ground. Relays 705 and 818, therefore, lock up independent ot the key 703 which restores as soon as itis released by the operator. Relay 705 closes a circuit from battery through the lamp 711, outer right-hand armature and liront Contact ot relay 705, interruptor 734, to ground. Lamp 711 is caused to dash in the circuit traced. Relay 705 also closes a cir- 4cuit from battery through the winding .oit relay 708, contact and inner right-hand armature of relay 705, conductor 735, winding of relay 823, back contact and lett-hand armature of relay 821, to ground. Relay 708 attracts its armatures and entends the incoming trunlr conductors 700 and 701 by` way of conductors 736 and 737 to the operating relays 801, 800 and 802 ot the callies indicator mechanism. Up to this time, relay 412 at the sender has been energized in series with relay 713. l/Vhen relay 708 attracts its armatures the battery supply through the windings of relay 713 is disconnected from conductors 700 and 701 and relay 412 deenergizes. The release of relay 412 opens the circuits of relays 411 and 414, permitting these relays to become deenergized. Relaysv713 and 712` at the trunk circuit, are also deenergized at this time. Re-

' lay 411 completes. a circuit from ground,

l ductor 736.

' opposite direction.

ent upon which pole of battery is connected tol a given side of the line. They may be also weak or strong, dependent upon whether a high or low resistance is included in the circuit. Relay 801 is polarized in such a manner as to respond only to an impulse created by a liow of current from the positive pole of battery over the conductor 737 and returnin toground by way of conhe relay 800 is polarized in such a manner as to respond only to an impulse created by a flow of current in the Relay 802 responds to strong im ulses of both positive and negative polarity but,'being marginal, does not operate on weak impulses.

When the impulse sequence switch 610 reaches position l, a circuit is closed from ground, which represents the positive pole of battery, upper contact 608 (1% to 2), conductor 620, back contact and inner armature of relay 411, lower contact 406 (14?, to 16), lower contact 324 (11), and thence over the upper or tip side of the line to conductor 736, windings of relay 801, 800 and 802 in series, conductor 737, and returning over the rin 323 (11?, lower contact 405 (14%; to 16), middle armature and back Contact Voi relay 411,

. conductor 621, upper contact 613 (l,L to 2),

high resistance 614, conductor 622, lower Contact 418 (16), to the negative pole of battery. Owing to the high resistance 614, this impulse is weak in character and is of such polarity as to cause the energization of relay 800. Relay 800 attracts its armature and closes a circuit from battery through the left-hand winding of relay 804, lefthand winding of relay 805, back contact and side of the line to lower contact.l

left-bandarmature of relay 804, contact and armature of relay 800, conductor 843, lefthand armature and contact of relay 818, contact and outer left-hand armature of relay 819 to ground. Relay 805 energizes and closes a circuit from battery, through the letthand winding of relay 804, left-hand winding of relay 805, riehtfhand winding of relay 804, contact and inner right-hand armature of relay 805, to the grounded conductor 843. Relay 804 however does not energize since its right-hand winding is shunt-l ed out at this time by the direct path through the armature and contact of relay 800 to the grounded conductor 843. Relay 805 closes a circuit from battery, through the winding of relay 808, back contact and inner armature of relay 807, contact and outer right-hand armature of relay 805 to the grounded conductor 843. Relay 808 attracts its armature and closes a circuit from battery through the windings of relays 808 and 807 in series, Contact and inner righthand armature of relay 808 to the grounded conductor 843. Relay 807, however, does not energize since its winding is shunted out by the direct path to ground, through the contact and outer right-hand armature of relay 805. As soon as sequence switch 610 leaves position 2, relay 800 releases and removes the shunt path from around the right-hand winding' of relay 804. Relay 804 thereupon energizes in series with relay/7805.

hile sequence switch 610 passes through positions 3?; to 3% a circuit is closed from the positive le of battery, upper contact 608 (3;,L to 3% conductor 620, thence over the tip side of the line through relays 801, 800 and 802, returning over the ring side ofthe line to conductor 621, upper contact 613 (32 to 3%), high resistance 614, conductor 622 to the negative pole of battery at the contact 418. This causes another weak impulse to be sent of the proper polarity for energizing the polarized relay 800. Relay 800 attracts its armature and closes a circuit from battery through the left-hand winding of relay 804, front contact and left-hand armature of said relay, contact and armature of relay 800 to the grounded conductor 843. This dlrect circuit to ground shunts out the left-hand winding of relay 805 causing this relay to deenergize. Relay 805 releases its armatures but a shunt circuit is maintained around the winding of rela 807 as follows: battery, through the winding of relay 808, back contact and inner armature of relay 807, Contact and inner right-hand armature of relay 804 to the grounded conductor 843. When sequence switch 610 moves out of position 3%, relay 800 releases its armature and opens the circuit through the left-hand winding of rela 804. Relay 805, being deenergized, no ot er circuit is offered for re-

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