US1483900A

US1483900A - Telephone-exchange system

Info

Publication number: US1483900A
Application number: US319309A
Authority: US
Inventors: Alben E Lundell
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1919-08-23
Filing date: 1919-08-23
Publication date: 1924-02-19
Anticipated expiration: 1941-02-19
Also published as: GB150300A; FR517392A; DE344229C

Description

Feb. '19 1924..- 1,483,900

A. E. LUNDELL.

TELEPHONEEXCHANGE sYsTEM Filed Aug. 2s, 1919 5 sheets-sheet i A/benE Lande 1919 s sheets-smet -2' ES @n WIM A; E. LUNDI-:LL

TELPHONE lEJXCIMNGE SYSTEM 4 Filed Aug. 23,

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//7 yeh for l/Sen E L11/7de# EWI Tw Feb. 19 1924.

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Patented Feb. 19, 1924.

Unirse stares PArenrorrrce.

ALBENE. LUNDn-LL, or NEW YORK, N. Y., 'AssreNon To WESTERN annotare Ycora- PANY, iNconroRAfrEn, or NEW Yon-K, N. Y.,.n conPoaA'rIoN or NEW Yoan.

TELEPHONE-EXCHANGE SYSTEM.

Yapplicati@ med August 23, 1919. sel-iai No. 319,309.

To @Zlio/m it may concern v Be it known that I, ALBEN E. LIUNDELL, ,a citizen of the United States, residing'. at `New York, in the county o'l Bronx, State of New York, have invented certain new and usetul Improvements in Telephone-EX- change Systems, oi which the following is a full, clear, concise,'andexact description.

This invention relates to' telephone eX- change systems, and more particularly to registering systems for automatic or semiautomatic telephone exchanges.

An lobject of the present invention is to Vcontrol selection of a called line according to a system of numbering different from the system used 'for designating the called line. A further object of the inventionis to rovide means for convenient changes in the method of selecting called lines without ret,-

Cil

i' and Fig. 3 (which is to be placed below erence to o-r change in their numerical designations.

This is accomplished by making use ot a selecting mechanism and a further object of the inventionprovides simple and .inexpensive means for settingV thel selecting mecha.- nism upon the selected point. .i n

Although the annexed description and drawings show va semi-automatic system, it is understoodthat the scope of the invention is not determined by the particular structure disclosed, reference being had Vto the appended claims Vfor that purpose.

In the drawings, Fig. lrrepresents a call-- ing subscribers line, a connecting circuit, and a selector switch; Fig. 2 (to be placed to the right of Fig. 1) a connector switch adapted to seize a called subscribers line;

4Fig-1') a selector controlling apparatus; and a registering apparatus by means of which the selector controlling apparatus and in turn the selector and connector switches may be set.`

The selector and sequence switches will not be disclosed in full in the following description of this system, since switches ot this type Vare well-known in the art. A complete description of such switches may be obtained from Patent No. 1,168,319, patented January 18, 1916, to A. E. Lundell.

When thel calling subscriber at vstation 100 desires to obtain a connection with'another subscriber, as, for example, station 200, he removes his receiver from the switchhook andV closes thereby a circuit for line relay LB, which in turn lights a calling lamp CL. The operator upon noticing lamp GL lighted, inserts plug 101 into jack 102 in which the calling line terminates-where-` upon a circuit is closed from grounded battery, through the winding of cut-oit relay CR, sleeve contacts of jack 102 and plug 101,

and the winding ot relay 103 t-o ground.

Relay103 closes a circuitv from ground, through the armature and front contact of relay .103, contact104 and power magnet of sequence switch 105 to ground battery. Normal spring 106 controls the movement of sequence switch` 105 through to position 2. A circuit is now closed from ground, se-` quence switch contact 107, conductor 108, contact300 of sequence switch 301, the l winding of rela-y 302 to grounded battery. The energization of the relay 302' closes a circuit from ground, lett-hand armature and front contact or relay 302, contact 303, and the power ,p magnet Lot sequence switch 301 to grounded battery. Normal spring 304 controls the movement ot' sequence switch 301 throughto position 2. Although the energizing circuit or" relay v302 'becomesA broken at contact 300 upon the movement ot' n sequence switch 301 out of position 1, relay 302 does not deenergize, a circuit for holding it energized being closed from grounded battery, windingl of relay 302, sequence .switch contact 305, right-hand armature-and front` contact of relay 302, conductor 306, and contact 109 of sequence switch v105- to ground. i

The operator depresses her-.listening key 110 and thereby connects her telephone set ing subscribers line, establishing a conver- 'sational circuit to him and, in accordance V111 to the connecting circuit and to the callf paratus provided for registering the numerical designation ot a called subscriber.

Only two sets of register keys are shown` in the Vupper right-hand corner ot Fig. 3, as it ico is thought to be sufficient for the purpose of describing the` present invention 'to describe the setting of interconnectingv means 112 and connectingfmeans 201 respectively in accorda-nce with two.` digits ofthe called subscribers number.

Itwill be2-obvious tof those skilled in thealrt that these switches or a greater number of switches maybe Vset grounded battery.

by meansot other digits et the numerical designation of the called subscribers line. n

It willalso be obvious to those skilled in the art that the jack-plug' connection at 102 and 101 can be replaced by Well-known line-tinding means and that by providing at subst-ation 100 a Well-known calling

dialthe registering keys

401, 402 and 405 can bevreplaced by switches ot .the step-by-step type, thereby converting` the system from the semi to the full automatic type. rSuch mechanically operated registers might beeolE the typeshoivn in the patent Yto Polinlroivsly 1,193,053, issued August 1,' 1910. Y

rissun'iing that the designation of the called subscrib'crs line is such as to ,cause the registering device 401 to be set in such a position-there being several other positions- Y as to open Contact 403, instead of one 'of the other contacts, which are opened when the device is set in such other positions; and to set registering device 402 toopen contact- 404, the ope-ration ot' starting device 405 closes the 'Following circuit; ground, sequence-switch contact 310, starting contact 405, right-hand Winding ot relay 406 to lay v406 lcloses a circuit 1from.grouml, lefthand arn'iature and front contacto't relay 400, conductor 407, sequence switch Contact 311, and power magnet ot sequence :switch 301'to grounded battery. r1he movement jot sequence switch 301 from position 2 through to position 3 is controlled b y normal spring 304. A circuitis noiv closed for up-drive magnet 408 from grounded battery, up-driif'e magnet 40S, sequence switchv contact P22, conductor 40T, let'tdia-nd front contact Vand armature ,of relay v400 to ground. Relay 400 has remained in its operated` position by virtue oi the closure ot' the hillovving circuit: grounded battery, right-hand Winding, front contact and armature ot' relay 400,co1nmu tatorsegment 409v` and commutator brush 410 to ground.V Relay406 is provided with a second winding 411 by meansot which the electrical condition ot' the tivo rovvs ot' termina-

ls

412 and 413 are tested in turn as the n'iovable brushes 4.15 and 414 come into contact therewith. Y

The row ot terminals `412 is arrangedY in groups, there being` as many terminalsin' each group as there are points in the registering' device 402, and as ina-ny groups as there are pointsm registering device `401.Y

The roiv of terminals 413 are also arranged in groups and the corresponding terminals of each group are connected together. For example, the iirst terminals of each group are connected together and to thetirst point 416 of registeringl device 402, the sec ond terminals of each group are connected together and to the second point `oit regis I tering device 402Y and so on. Y It will be seen therefore,that 'there can be provided as The energization ot remany terminalsin the translator device 417 device 401,'and that Contact 404 has been openel by the operation ot registering.de`

vice 402, the upward"movement of trans-V lator 417 is stopped onlyv V1vlien brushes 414 Y and 415 contact with terminals in the second groin) and specifically the sixth terminal of the second group, since the lett-hand Winding'V ot' lrelay 400 lines a closed circuit'ivhen j the brushes 414. andA 415 Contact with any terminals previous to those mentioned. Since the electrica-l condition set up at'the time the brushes contact. with one ot' thesel previous sets of terminals is dierent from that set up at another previous terminal, ttor the sake ol brevity 'only tivo of theser .cases will be described in detail.,` lt maybe readily understood thatthe other conditions are similar, vthe only differences beingv in regard to the particular wiring Contact and terminal numbers. lYhen, `for example, the

brushes

414 and 415 are in engagen'ientwith the tirstI termi-nal ot the tirst group,l a eircuit is closed from ground, contact 416 of registering device "402, conductors 418 and 4.19, brush-414, to the test Winding 411 ot' relay 406. Another circuit is closed` from ground, contact 420 of -registering device 401, conductor 421, brush 415 to relay 400. lllhen, for example, brushes414 and 415 are in engagement withv thel second terminal ot the trst group,` the following,- circuit is closed: ground, contact of registoring,` device 402, conductor 423, brush 414, to test Winding 411 of relay 406.` VIt will be'seen, therefore,` that the tcstrelay 406 cannot dcenergize until

brushes

415 and 414 are Vinr engagement `u'itlithe open contacts of registering devices 401; and 402 respectively, and the commutator brush 410 reaches an insulated segment of the commutator Contact 409.

lpon the release of relay 400, the circuit ot the upedrive magnet 408 is opened, causing the brushes ol the translator device 417 to` come to rest` and closing thev followingr circuit: 0'round left-hand armature and i back contact et test relay 406, sequence switch cont-actV 318, and power nfiagnet ofscquence Sivit-eh 301.Y The sequence switch 301 isvv moved through .to spring 304. y. Y Y,

A fundamental circuit is vnoiv closedv from i Igrounded battery, through winding. of relay contact oli counting` relay O', Winding of'.

stepping relay 315, conductor'316, sequence Vsivitc i contact 116 to ground. Y Relays 113 and position 4 vby normal 3l5beconie energized; Y Bela-y 113 closes the Van alternate path through its left-handv armature and front Contact and the sequence switch contact 119. 'Upon theenergization of relay 315, a circuit is closed from ground, front contact and armaturefof relay 315, sequence switch contact 317, conductor 318, brush 424, stationary contact 425, conductor 426, conductor 42T, conductor 332, the armatuic and back Contact of the No.V 9 counting relay, winding of counting relay 9, to grounded battery. The counting relay 9 closes a circuit trom ground, through sequence switch contact 320, conductor 321, armature and .front contact of counting relay- 9, winding of counting. relay 9', winding of counting relay 9 to grounded battery. Counting relay 9 cannot become energized, however, because ot a short-.circuit around its winding, there'being a direct ground on its armature and back contact which originated at the front contact of stepping relay 315 as described above. A circuit is also closed for the lip-drive magnet 120 of selector 'switch 112 by way of sequence switch contact 121 and right-handr frontvcontact and armature of relay 113. The energization of magnet 120 attracts armature 122,

pressing brush rod 123 against the constantly'driven roller 121. This imparts 'an upward motion to the brush rod '123 `and drives selector 'wipers 121, A125, 126, and

commutator brushes 127l andv 128 in an upward direction. lVipers 124,r` 125 and 126 come into contactwith corresponding rows of stationary terminals such as shown, andV commutator brushes 12T and 128 traverse the conducting and'insulated segments Vof connnutator plate 130. lVhen the commutator brush 128 contacts with a conducting segment `131, ground is connected through the segment, conductor 132, sequence switch Vcontact3133,.to the conductor 115, thereby short-circuiting relay 315, the'other side of the winding of which is also connected to the ground atsequence'switch spring 116.

'Relay 315 opens atits front contact the short-circuit around the No. 9 counting re-v lay,permitting the energization of this relay, and conductor 332 becomes connected by way .oit the armature and front contact of the No. 9" counting relay to the varmature and back contact of the No; 8 counting relay. The arrangement of the No. 8 counting'relay and its mate, the No. 8 relay, .as wellvas'the remaining pairs ot counting relays is similar to that of the No. 9 and blo.`

9 counting v relays previously described. `When the coininutator brush l28leavesconducting segment 131, .relay 315 is again en ergizedi This in turn operates counting re lay 8 whichV accordingly.connectsinto cir vcuit the No. 8 counting relay but the latter cannot operate because ot ya short-circuit corresponding tol the one described :iforthe No. 9 Yrelay previously.` In substantially the saine manner the remainder of the counting relay chain cooperatesv with the opening and closure oi the ground at com-' muta-tor brush 128, as the brush rod` conf tinues its upward motion over the vinsulated and conducting segments, until after i 10 steps, when the 0 counting relay becomes energized. This opens the fundamental circuit, including tlie windings .of relay315 and 113, and closes the following circuit:v ground, sequence switch contact 324, inner arma-ture and front contactl of the 0 counting relay, power magnet of sequence switch 301, to grounded battery, thereby causing the moveinent'of the sequence switchoutoiv position L1, and because of the normal spring 304: into position 6. The duration of the opening of the sequence switch contact 320 between positions 4 and 6 is suliicient tore llease all of vthe counting relays which-have been locked up in; t-he selecting operation `just described. Y

lture and back contact of relay 113, sequence switch contact, 135, conductor 118. and the power magnet ot sequence switch to' grounded battery, t moving the sequence switch into position It will be noted that the release of relay v113V alsoopens the circuit of the up-drive magnet 120, thereby stopping the brushes in their displaced lposition. y

lVhen the sequence switch reaches position 6, acircuit isclosed from ground, sequence switchcontact 136, right-hand Winding of relay 138, Vtogrounded battery, for energizing relay v138.

cuit from ground, through the right-hand armature and front contact of relay 138, se-

quence switch Contact 140, conductor 118, V

and the power magnet ot sequence switch 105 to. grounded battery, whereupon the seL i Vquence switch moves into position 72 lf the trunk first reached were busy, whenI the energizing circuit orrelay138 became yopen Aat sequence switchy Contact 136, this relay would be maintained energized,;becausey 0f a circuit consisting of Ithelett-handwinding-,middle front contact `and armature of this relay, conductor152 to the test contact ont the busytrunk. l e ,l

. 115,. The operation ofi-clay 138 closes afcir- The up-,driif'e'magnet 120 wouldL then be switch Contact 145, up-drive magnet 120, toY

grounded battery. vWhen the wipers 124,

' 125 and 126 reach the terminals oan idle trunk, and .let us say now that trunk 202, 203 Yand 204 Vis the .irst .idle trunk, no ground circuiti.V .will be aifailable for holding energized tlie'lei't-hand winding oi re- 133 so that when tliecoininutator brush. 127 engages aninsulated segment 141 of the coniuiutator plate 130, rela-y 138Ybeconies deenei'gized and opens the circuit of magnet 120.A The upward movement of the brush rod 123 is'thcrehy arrested and the wipers 124, 125 and v126 remain in engagement with 'the terminals connected to trunk conductors 202, and 204. l

The releaseof'i'elay 133 closes a circuit by way of sequence switch Contact 146, conductor'118, power magnet 'ot sequence switch 105 to "grounded battery, moving the sequence switch out of position 7 and into position 11. Sequence switch 301 is now in position (i-as previously described, and se-V quence switch 205 is in position 1, since it was assumed that

trunk

202, 203 and 204, which terminates in the selector 201 and sequence switch shown in Fig. 2 wasidle, that is in the normal position.

A, new fundamental circuit is now closed as vfollows: groundedbattery, winding oiu relay 207, sequence switch contact 208, trunk conductor 202, wiper 124 of selector 112, sequence switch contact 150, conductor 115, sequence switch Contact 314, outer ar vmature and 'baclr contact of the 0 counting yit' relay, windingoi stepping relay 315, conductor 310, sequence switch contact 151, wi per 1250ic the selector 112, trunk conductor 203, and sequence switch contact 200'to ground.

Relay 207 closes a circuit -from ground, through its right-hand armature and front Contact. contact 210, and the power magnet of sequence switch v205 to grounded battery, and this sequence switch is thereuponii'ioved into position 2. rlhe relay 207. locks up througlijits left-handV front contact andarmature and sequence switch Contact 211 independent of contact 208, and thus will not become deencrgized lwhenV the .sequence switch 205 leaves positionl and Contactr 208 becomes opened. In position 2 of sequence switch 205 a circuit is closedV from ground,

through sequence switch contact 212, the winding of rela-y 20S to grounded battery, and this relay upon operating closes acircuit from ground, through its right-hand arr mature and Jfront contact, contact 213 and.v the'power magnet of sequence switch 205 to grounded battery, whereupon this Sequence switch is moved into position 3. Relay 206,

although its energizing circuit is opened at continued closure' of` the fcllowingcircuit: ground, sequence switch contact 153 of Fig.VV

'1, bach ContactV and middle armaturefo't' re- Y lay 133, conductor .152,brush. 126, conductor 204, f lett-hand f yarmature and :trent vContact 'ot relay 206 of Fig. 2,- thrcugh the winding of this relay to grounded-batteryj y Y Y The upfdrive magnct215 of connector 201 is now energized by'way o1E a circuit originating at the right-hand yarmature ot' relay 207, right-hand t'ront contact of this relay, sequence switch Contact 216, up-drive magnet 215, to grounded battery. The armature 217 is' accordinglyv attracted and presses brush rod `213 against constantly driven roller 219, thereby causing the'connector switch wipers 220., 221, 222, and cominutator brush 223 to move in an upward* direction. a contact bank in which called lines terminate, the coinniutator brush 223 contacting with conducting and insulated segments, such as and 220, ot the commutator plate 227 Asa result of the energization ot' relay 315 which occurred when the new fundamental circuit. including'- relay 207 was closed, a circuit is Vnow closed from ground, through the front contact and armature ot relay 315 of Fig. 3, sequence switch contact 330, conductor 331, wiper 428, terminal 429 ofntranslator 417, conductor 430, conductor 431, conductor 432, armature and back contact-of- No. 3 counting relay, winding Of No. 3 countingrelay to grounded battery. The counting relay chain under control of stepping relay 315, ope-ratesv` in substantially the same manner as previouslyA described. Theshort circuits for the stepping relay are caused by the closure of a4 circuit from ground, through Vcommutator brush 223, conducting segment 225', conductor 230, se-

quence switch cont-act 231, to the conductor 2PZ-which is, as previously described, connected through to thev stepping` relay: 315, and the current from theV grounded .battery through the winding o1? relay 20.7v now` flows .to ground at comniutator brush 223.-? After tour. impulses have beencountedoff-(conductor 431 having beenV connected. to the No. 3 pairof counting relays) the 0 counting relay opens the fundamental Vcircuit at its outer armature and when commutator brush counting relay also closes a circuit from ground, through sequence switchV Contact `the inner armature and iront 'contact of the 0 counting relay through thepower magnet ciC sequence switch 301 to lgrounded battery, for moving the sequence switch out 01" position 6, which because Yof the norma spring 304 continues into position 16.;l

The wipers mentionedA traversel second section 442 of the connecting rack 443. By ymeans of this connecting rack the lnumber of impulses to be transmitted over the fundamental circuit 115 and 316 'can be changed at will in a simple and efficient manner. v

A circuit is then -closed from ground, through sequence switch contact 335, conductor 336, Contact 155 and the vpower magnet ot' sequence switch 105 to groundedbattery, and sequence switch 105 is accordingly moved. out of position 11, andv because of normal spring 106 moves into position 16. As soon as sequence switch 105 moves out ot position 11,'contact 109 Aof this sequence switch is opened and relay 302 becomes deenergized. A circuit is thereupon closed from ground, through the left-hand armature and back contact of relay 302, contact 337. and the power magnet of sequence switch 301 to grounded battery for moving this sequence switch out of position 16 into `position 18. In positions 17 and 18 of sequence switch 301, contact 333 closes a circuit from ground to release

magnets

433, 434 and 440, through these release magnets to grounded battery,` and the energization ot the releasel magnets restores the associated registering` devices to normal. In position 18 ot sequence switch 301 a. circuit is closed from sequence switchcontact 334 toconductor 338 to the down-drive magnet 435 of the translator 417, causing' the brush rodV 436, the wipers 414,415, 424, 428, and the cominutator brushes 410 and 437 to be moved in a downward direction. IVhen cominutator brush 437 strikes conducting segf ment 433 a ,circuit is closed from ground,

commutator brush 437, conducting segment 438, conductor 439, sequence switch contact 337, and power magnet of sequence switch 301 to grounded battery, moving sequence 'switch 301 outI of position 18 and into its normal position ,1. The opening of sequence` switch contact 334 deenergizes dowii-drive magnet 435. It will be noted that the selector controlling apparatus, the translator 417, and the registering devices of Fig. 3 are now fully restored to their normal position and ready to be used on the next call.

Upon the deenergization of relay 207 of battery for moving this sequence switch out ot position 3 into position 13.. After the testing of Vthe selected line in accordance with any well-known manner of testing such lines, a ringing circuit is closed from ringing current source 234, through the Winding i ot relay-235, sequence switch Contact 236, wiper 221, the called substation circuit, wiper 220l and sequence switch contact ,23.71110 ground. Relay 235 is `marginal and does not operate `.upon the relativelysm-all current which isl permitted to flow throughV the `condenser at Vthe called station, but upon vthe removalof the receiver the current low is increased and the marginal relay 235 becomes operated, thereby closing the follow? ing' circuit: ground, sequence switch contact238, the lfront contact and armature'ot' relay 235, the power magnet of sequence switch 205 to groundedbattery. Sequence switch 205 is moved out of position 13 and into position 16. The movement of thesequence switch out of position 13 necessarily releases marginal relay 235.` The calling and called subscriber are now telephonicallyconnected, `the. talking circuit being indicated by relatively heavy lines in Figs. 1 and 2.

Upon completion of the conversation tlie subscribers replace their receivers on the switchhooks and cause in awell-known manner the actuation ot

supervisory devicesl

160 and 161, .together with any local signals `which it may be desirable to place under the control ot these devices. The operator upon noticing the actuation of these signals removes tlie plug 101 from jack 102, whereupon cut-oliij relay CRand relay 103 areV released. In the case of a full automatic exchange, the rtrain of switches including the linefinding means, lis restored. when the subscribers replace their receiver, in a manner well-known in the art; and accordingly relays CR and 103 are released. A circuit is then closed from ground, through the arma-ture and back contact of relay 103, sequence switch contact 162, the power magnet of sequence switch 105 to grounded battery, whereupon this sequence switch is moved out of position 16 and into position 18. Inthis last-mentioned position a circuit is closed from ground, sequence switch contact 164, downdrive magnet 163, to grounded battery, and armature 165 upon becoming attracted causes the restoration of brush rod 123 in a downward direction.

Upon reaching its normal position a circuit is closed by way of cominutator brush 127, conducting segment 167, which is closed only at the normal position, conductor 168,'Se-

quenceswitch contact 169, conductor 118, the power magnet of sequence switch 105, to grounded battery,.moving this sequence switch out of position 18 and into norma-l position 1. IVhen the sequence switch leaves position 18 magnet 163 becomes deenergized.

Relay 206 of Fig. 2 is released as a result of the opening of sequence switch contact 153, which occurred when sequence switch 105 moved from position'l to 18. A temporary make busy circuit kis closed from ground, through se uence switch contact 240, through the le t-hand back contact and armature of relay 206 to conductor 204 i'or maintaining the busy test condition on the multiple bank terminal connected thereto during the period that connector switch 201 is being restored. In, consequence ofthe release of relay 206 a circuit is closed .from ground, right-hand armature and back contact ot this relay, sequence switch contact 241, power magnet of sequence switch 205 to grounded battery,

causing the movement of this sequence switch out ot' position 16 and into position 18. This in turn closes a circuit from ground, through sequence switch contact 242 closed in position 18, winding of downdrive magnet 243 to grounded battery. The energization Vof down-drive magnet 243 causes the restoration of connector 201 to the normal position. Then commutator brush '223 contacts with conducting segment 244, a circuit is closed from ground, through Vcommutator .brush 223, 'conducting segment 244, conductor 245 and Contact 246 through the power magnet of sequence switch 205 to `grounded battery for moving this sequence switch out of position 18 and into its normal position 1. The opening of sequence switch contact 242 releases dowirdrive magnet 243 andthe opening of contact 240 permits the

Atrunk

202, 203, 204 tofbe again seized for a kbranch ot said circuit extending from stav tionary contacts of said switch, and means for selectively opening any one of the circuit extensions oi each branch tojointly directv the movement of said switch under the control of said relay.

2. In a telephone exchange system, a selector switch, a control relay therefor, a branched circuit for said relay extending to movable contacts o'tsaid switch, a plurality ot normally closed extensions of each branch -of said Acircuit extending from stationary contacts of said switch, and means for simultaneously and selectively opening an exltension of each branch of said circuit to jointly direct the movement of said switch underthe control of said relay.

3. Ina telephone exchange system, a selector switch, a test relay for controlling the movement of said switch, a branchedy circuit for said relay extending toinovable contacts of said switch, a plurality of extensions of said circuit extending from stationary contacts of said switch, and means tor selectivelyk controlling the circuit extensions of said branches invarying combinations to` direct the movement of said switch under the control of said test relay.

4. In a telephone exchange system, a selector switch, a plurality of -test circuits ai'- raiiged in groups, means for selectively al tering the test condition in any circuit in each of said groups, and means for testing circuits in all of thek groups simultaneously and for advancing said switch toa point jointly predetermined by the test condition in the circuits selectively altered.

5. In a telephone exchange system, a' se-` ber of branches of said test circuit to a corresponding number ot contact devices,

and means for stopping said switch` upon reaching a resting position in which all branches of the test circuit are opened.

6. In a telephone exchange system, a selector switch having al plurality of resting positions, a multiple test circuit with branches, a plurality of normally closed contact devices tor each ot' said branches, means for simultaneously connectingk a number ot' branches of said test circuit to a corresponding number of contact devices, means for advancing said switch whenever the test circuit includes one or more closed contact devices, and means for stopping said switch upon reaching a resting position in which all branches ot the test circuit are opened.

7. In a telephone exchange system, a selector switch having a plurality of resting positions, a multiple test circuit with branches, a plurality of normally closed extensions for each branch of saidy circuit, means tor advancing said switch and for associating each ot said branches with the extensions thereof, means for opening any ot said extensions and means for arresting said switch. when each branch of said Vtest circuit becomes associated with an open ex'- tension thereof, the number o1 resting positions being equal to or less in number than the product ot the number of extensions in all branches. Y

8. An electrical system tor selecting terminals comprising an apparatus havingregisters corresponding to groups ofsome numerical system, a translator Vcontrolled by said register, a selector controlling apparatus for eiecting the selection of terminals in accordance with la numerical group different from that first named, and means for 'altering the relation between said transla-l groups with said controlling means, a source v of testing potential normally connected to all of said terminals and means comprislng registering devices for selectively discon-V necting said potential from a terminal of 'each group, whereby said switch may be selectively positioned 'in accordance with said operated registering devices.

11. In a telephone exchange system, a selector switch, means for controlling the advance of said switch, a plurality of groups ot' testing terminals, each of said groups being divided into a plurality of subgroups, wipers associated with said switch for simultaneously connecting terminals in all of said groups with said controlling means, a source ot testing potential normally connected to all of said terminals and means comp-rising registering` devices for selectively disconnecting said potential from the terminals of any sub-grouprof one of said groups and from lany terminal of one of the sub-groups of another ot said groups, whereby said switch may be positioned in accordance with said operated registering devices.

12. In a telephone exchange system, switching mechanism, a plurality 'of registering devices for recording the designations of desired lines, means controlled by said registering devices for controlling said switching mechanism to extend connections to said desired lines, and means comprising a cross-connecting rack associated with said registering devices and said control means adapted to be readily changed to modify the control of -said switching mechanism by said registering devices.

13. In a telephone exchange system, switching mechanism, a plurality of registering devices for recording the designations of desired lines, means controlled by said registering devices for controlling said switching mechanism to extend connections to said desired lines, and la cross connecting rack interposed between said registering devices and said control means 'having jumper connections adapted to be readily changed to modify the control of said switching mechanism by said registering Y devices.

14. In a telephone exchange system, switching mechanism, a plurality of registering devices for recording the design-ations of desired lines, a translator switch, means for setting said switch into a position jointly determined by said'registeringdevices, means 'for controlling said switching mechanism to extend connections to said desired lines and means interposed between the bank terminals of said switch and said control means adapted to be readily changed to modify the control of said switching mechanism by said registering devices.

15. In a telephone exchange system, switching mechanism, a plurality of registering devices for recording the designations of desired lines, a translator switch, means for setting said switch into a position jointly determined by said registering devices, means for controlling said switching mechanism to extend connections to said desired lines, and a cross connecting rack interposed between the bank terminals of said switch and said control means adapted to be readily changed to .modify the control of said switching mechanism by said registering devices.

In witness whereof, I hereunto subscribe my name this 21st day of August, A. D., 1919.

ALBEN E. LUNDELL.