US1578420A - Automatic telephone system - Google Patents

Description

March 30,1926.

J. 1-; GARDNER I AUTOIATIC' TELEPHONE SYSTEM 6 Sh ea ts-She'e't 2 Filed Oct. 11. 1921 JQN March 30 1926;

' J. E'. GARDNER AUTUIATIC TELEPHONE SYSTEII Filed Oct. 11, 1921 6 sheets-Sheet 3 1,578,420 J. E. GARDNER .7 Auzrmnc TELEPHONE svs'fzu 1 Filed octnn 1921 sheets-sheet 4 4i tenor-* John EEarcfnsJ:

March so 1926. 1.52 3

' J. E. GARDNER AUTOIATIC TELEPHONE SYSTEM Filed 001;. 11, 1921 6 Sheets-Sheet 5.

Inuen ur J. E. GARDNER I -AUTOIATIC wsnsrnons SYSTEM Filed Opt. 11, 1921 5 s t sh t 6 I IHIIIII W lllll W" i m mun w R m Patented Mar. 30, 1 926.

um'rso srArgss 'PATEnrioFr cs.

JOHN E. GARDNER, oE CHICAGO, ILLINOIS; ASSIGNOR, BYMESNE ASSIGNMENTS, r0

AUTOMATIC ELECTRIC me], or CHICAGO, iLLrnors, A CORPORATION 0E nEEn- WARE.

. AUTOMATIC rELErHoNEsYsTEM.

Application filed October 11, 1921. Serial No. 5o7,o1e.

' To all whom it may concern: I

Be it known that 1, JOHN E. GARDNER, a subject of the King of Great Britain, and a resident of Chicago, Cook County, and State of Illinois, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following specification. i

The present invention relates in general to automatic telephone systems, and has for its principal object the provision of a new and improved trunking system for automatic exchanges.

In carrying out the above general object of the invention a number of new features have been designed, the more important of which will be pointed out below.

One of the features of the invention is the provision of a new and improved combined finder and connector switch which is adapted to operate either as a finder switch to hunt for and connect withthe calling line or as a connector switch to connect with a called line. Linked with each of these combination switches is a secondary switch. This secondary switch is of a novel type inasmuch as it is adapted to operate either as a secondary line switch when itsassociated combination switch is operating as a finder or as a finder when its associated. switch is to be used as a connector.

' Another feature of the invention is to provide an improved starting circuit for these combination switches, whereby, in the normal operation of the system when these switches are operating as finder switches, only the combination switches whose associated secondary switches having their wipers standing in engagement with an idle trunk line leading to a selector switch will be started. Means are also provided, so that if all of the combination switches are busy. due partl'y to their beingused in setting up connections and partly because their'asso: ciated secondary switches are associated with busy trunk lines, the first idle one of these combination switches is started and its linked secondary switch'is caused to seek an idle trunk line. i i

A still further feature of the invention is to provide means, whereby, while one of the combined switches is hunting as a finder its associated switch may not be operated as i There are other features of the invention not now specifically mentioned which, to; gether with the foregoing, will be explained fully hereinafter with reference to the accompanying drawings. I

As shown in the drawings, the invention has been applied to a ten thousand line system, though, of course,- the size of the systemmay be increased or decreased by the addition or elimination of selector switches at the proper point in the trunking system.

Referring now to thedrawings compris ing Figs. 16, inclusive, Figsgl, 2,3, and a-show a circuit diagram of a complete con nection between a calling. substation A and a called substation A. Theapparatus involved in this connection includes a COIl'lbif nation switch F, secondary switch C, first and second selectors E' and E, secondary switch G and combination switch F. Fig.

5, shows the starting circuits diagrammatically of a group of. the before mentioned combination switches. Fig. 6, shows the general trunking layout of the system.

Referring now particularly to Fig. 1, there is shown a subscribers substation A of the well known automatic type having, in addition to the usual talking instrumentalities, a calling device S. The line of the substation terminates at the exchange in mul tipled bank contact-s accessible-tea group of combination switches, one of the latter being shown at F. In addition tothe above the line of the substation A has associated with it a combined line and cutoff relay 1 7.

The combined switch F isone of a group of combination switches which have access to the lineof the substation The switch F isof the usual Strowger vertical and certain conditions it is adapted to operate as a finder switch, it is provided with a vertical bank having a bank contact for each level.

Inasmuch as the switches of the group such as are adapted to beused either as finder switches or connector switches, instead of having finder switches and 10 connector switches, it is possible to handle vthe same amount of traffic with a lesser This number-of these combination switches.

is well understood because in a situation of f' these combination switches which are used for either incoming'or outgoing calls. Thus,

in the present case, where ordinarily it would require 10 connector switches and 10 finder switches to handle the traffic of a group of 100; lines only about of these combination switches are necessary to handle the same amount of traffic.

Associated with each of these combmation switches is a secondary switch, the one associated with the combination switch F being shown in the drawings at C, Fig. 2.

' The secondary switch C is ofthe same general mechanical construction as that of the 7 well known rotary line switches and has access to trunk lines extending to first selector switches and to other trunk lines terminating in the banks. of second selector switches. Should it be found that the outlector switches.

going traffic from the group of combination switches exceed'lO calls at any one instant the secondary .switch ,0 will be given access to more than ten, trunk lines extending to first selector switches and this maybe as high as 15 in case there are'times when there are 15 calls from the combination switches. On the other hand should there be a larger number of incoming calls than 10 at any given instant the rotary switch C will have access to a larger number of trunk lines terminating in the banks of the final se- I Depending upon the de-' mands of traffic the rot'ary switch C is provided with more or'less bank contacts and has access to a greater or less number of trunk lines extending: to first selector switches or. incoming from second selector switches. One'of the outgoing trunk-lines accessible to the secondary switch C is shown in the drawings terminating in the first selector E. r 3 I b The first selector E is a switch of the usual Vertical and rotary type and has access to trunk lines extending to second sclector switches one of the latter being shown at E, Fig. 3.

The selector E is similar to the selector E already described'and has access to trunk lines terminating in the banks of secondary switches such asC.

The equipment associated with one of these trunklines is shown in the drawings and comprises a combined line andc'ut off relay 312.

The secondary switch C has associated with it the combination switch F. The switches C and F are similar to the switches C and F already described and serve to illustrate theoperation when the switch C is used as a finder and the switch F is used as a connector.

Fig. 5, shows the starting loop circuit "of a group of 100' subscribers lines, whereby the calling subscribers of the'group control the starting of an idle combination switch asa finder. v v

Fig. 6, shows a general trunking diagram of a -10,000 line system which will now be referred to for a briefdescription ofthe manner in which a call is made from one subscriber to another.. In order to describe this operation it will be assumed that the subscriber at substation A in the first thousand group desires to call a subscriber at substation A whose line is located in the fifth thousand. In order to do this the call ing subscriber will remove his receiver and operate his calling device in accordance with the number assigned to the substation A.

When the receiver is removed at substation A an idle combination switch such as F, whose associated secondary switch C is standing with its wipe-rs in engagement with o an idle trunk line extending to a first selector switch, is automatically operated to connect the calling line with the secondary switch C. The latter switch operates to extend the calling line to a first selector switch such as E. The calling subscriber may then call the first digit in the desired. number which causes the first selector E to be raised to the proper level and to thereafter select an idle'trunk line'extending to a second selector switch. In the present case as the subscriber at substation ,A is located in the first thousand the first selector E will'be operated to the fifth level. In response to the next digit of the called number an idle second selectorsuch as E is operated to the desired level in order to select-the proper group of combination switches which have access to the substation A. In the present case the substation A is shown to be in the Second hundred gr p f the fifth thousand.

the seized trunk line and extend it to its" associated combination switch F; 1VVhen the last two digits of the called substation are dialled by the calling subscriber the combination switch F is operated as a connector switch to connect with the called line and to automatically signal the subscriber thereon. WVhen the conversation is terminated the release of the connection takes place upon the calling subscriber replacing his receiver upon the switch hook.

Having briefly described the method of establishing a connection with reference to the trunking diagram of Fig. 6, a detailed description of the circuit operation of the various switches will now be given. For this purpose it will be assumed,

as before, that the subscriber at substation A in the first thousand desires to call. the subscriber at substation A in the fifth thousand. In order to do this the subscriber will remove his-receiver and operate his sender S in accordance with the l'digits which constitute the number of the substation A.

When the receiver removed at substation A a circuit is completed for the winding 15 of the relay 17 in series with the common relay 30, over'the line conductors 11 and 12 in series. However, the coil 15' of the relay 17 only attracts the armature 21 and causes it to disengage its resting contact and engage its working contact and has no effect on its armatures 20 and 22. This operation is due to the peculiar con-- struction of relay 17 which is so arranged that when the coil 15 is energized the armature is completely attracted against the core of this coil but when the coil 16 is energized the fulcrum of the armature is changed and the armature given a longer stroke so that it operates all'springs. This construction is shown and described in detail in the co-pending application of M. L. Nelson, Serial No. 498,630, filed August 19, 1921. The relay 30 is common to 10 subscribers lines, that is, all that are located in one level of the combination switches. By the operation of the armature 21 of the combined line and cut off relay 17 ground is disconnected from the multiple test contacts in the banks of the associatedgroup' of combination switches, thus rendering theline of the substation A selectable.v The relay 30, upon energizing, at its armature 82 completes a circuit for starting the first idle combination switch as a finder which,

we will assume, is the switch F. This cir cuit may be traced from ground by way of armature 32 and its front contact, conductor 38, armature 100 and its back contact, armature 81 and its back contact, and through the winding of the relay 58 to battery. Another result of the operation of armature 32 is that ground is disconnected from the vertical test contact 42 so as to enable the switch F to connect with the line of the substation A. Relay 58, upon energizing, at its armature 98 disconnects ground from the armature 107, at the front contact of this armature closes the circuit general disconnecting the test wiper 151, and at armature 92 prepares the circuit of the relay 62. The slow acting relay 60, upon operat1ng,-at its armature 106 opens a point in the release circuit, at its armature-105 places ground upon the release trunk conductor 162, and at armature 10% opens a point 1n the circuit of the relay 51; Relay .56, upon energizing, at armature 86 prepares a point in the locking circuit of the rotary test relay 52, at armature prepares the rotary testing circuit, and at armature 8 1 opens a point in the circuit of the relay 51. As the combination switch is now 111 normal position the vertical test wiper 15 1 is as sociated with the vertical test contact 10 which is permanently grounded. A circuit is now completed. which extends from the grounded contact 10, vertical test wiper 15 1, back contactand armature 68, armature 121 and its back contact, armature and its front contact, and through the winding of the vertical test relay 57 to battery. Relay 57 is immediately energized 'over this circuit and, upon'operating, at its armature 89 establishes a locking circuit for itself and at its armature 90 sends an impulse of current over the following path: Ground by way of front contact and armature 90, offnormal springs 124 and 123, through the winding of the slow acting relay 54:, and thence through the winding of the vertical magnet 1.16 to battery. Magnet 116 operates to raise the switch wipers 150 154, inclusive, one step and at its armature 121 opens the locking circuit of the test relay 57, which deenergizes opening the circuit 'of the vertical magnet 116 which deenergizes also. If the calling subscribers line ls'not located in the first level there Wlll .be a ground potentiol upon the test contact lland the vertical test relay 57 will be again energized and will operate in the same manner as before described to complete the circuit of the vertical magnet 116. The vertical magnet 116 operates to raise the switch wipers opposite the next level of bank contacts and to break the locking circuit of the test relay 57. The alternate operation of the test relay 57 and the vertical magnet 116 will continue until the switch wipers are raised opposite the level of bank contacts in which is terminated the contact set associated with the substation A. In the present case the substation A is located in the. second level. therefore, immediately upon the switch wipers being brought: opposite the second level there will be no ground .the rotary magnet which deenergizes also.

.cuit of the rotary magnet 115.

potential present upon the test contact 42, the vertical test relay 57 will notbeenergized and the vertical operation of the switch will cease. -The slow acting relay 54 is energized in series with the vertical magnet 116 and maintains its armature attracted throughout the vertical movement of the switch. Relay 54, upon operating, at its armature 79 maintains the'continuity of the vertical magnet circuit, as upon the first vertical step of the switch shaft the off-nornal springs are shifted and the circuit of the vertical magnet includesthe offnormal springs 124 and 125 and armature '79 and its front contact, and at armature 78 closes the circuit of the rotary test relay 52. Relay 52,. upon operating, at armature 72-estalolishes a locking circuit for itself and at armature 78 prepares a point in the cir- Upon the termination of the vertical movement of the switch the slow acting relay 5 1 deenergizes and the rotary magnet 115 is energized over a circuit extending from ground on release trunk conductor 82,-armature 85 and its front contact, armature 78 and its back contact, armature 73 and its front contact, through the winding of the slow acting relay 53, back contact and armature 69, and through the winding of the rotary magnet 115 to battery. The rotary magnet 115 is operated over this circuit and advances the switch w1pers-150158, inclusive, 111150.611- ga ement with the first set of bank contacts in the second level and at armature 120 opens the locking circuitof the relay 52, which deenerglzes opening the circult of The slow acting relay 53 is energized in series with the rotary magnet 115 and operates at its armature 7 1 to connect the test w per 1.52 to the test relay 52. If the line of the calling substation A is not associated with the first set of bank contacts there will be a ground potential present upon the testcontact engaged by the test wiper 152 and the test relay 52 will be energized. Relay 52, upon operating, at its armature 72 establishes a locking circuit for itself and at its armature 73 completes the circuit of the rotary magnet 115. Magnet 115 operates to rotate the switch wipers another step into engagement with the next set of bank contacts and at armature120 opens the locking circuit of the test relay 52. The alternate operation of the test relay 52 and the rotary magnet 115 continues until the switch wipers (l153, inclusive, are rotated into engagement with the set of bank contacts associated with the calling line which, we will assume. are the bank contacts -28, inclusive. Then this occurs there will be no ground connected to the test contact 27, no circuit will be completed for the test relay 52 and the rotation of the switch will cease. Then, following the deenergization 0f the slow acting relay 53, a circuit is completed which may be traced from ground on release trunk conductor 82, armaturej72 and its back contact, through the lower winding of the switching relay 50, back contact and armature 7 1, front contact andarmature 98, test wiper 152, test contact 27, armature 21 and its front contact, and through the winding of the coil 16 of the combination line and cut oflf relay 17 tobat tery. The cut off coil 16 and the switching relay are immediatelyenergized over this circuit. The coil 16, upon energizin at its armatures 20and 22 disconnects the line relay15 from the calling line and at the .same time opens the circuit of the common relay 30. The coil 15 immediately deener- 'gizes but thearmature 21 remains attracted by the action of the coil 16.

In the combination switch F, relay 50,

upon operating, at its armature 67 estab-fl group ofbanks of the combination switches so that the line of the substation A can not be connected to while the present call is in progress. a

It will be remembered that as soon as the combination switch F was seized ground was placed upon the release trunk conductor 162. By this operation a circuit is completed for the line relay 175 of the secondary, switch C. This ground also places a short circuit around the relay-176 for a purpose which will appear fully later, Upon operating, relay 175 at armature 185 completes a circuit wvhich includes the switching relay 178 and the motor magnet 17 9 in series, at its armature 186 disconnects the test wiper 206 from 'the conductor 161 and connects the said test wiper to a point midway between the switching relay and the motor magnet 179. In the normal operation of the system the secondary switch C is standing with its wipers in engagement with an idle trunk l ne otherwise its associated combination switch F would not have been started. It will be assumed that this trunk line isthe one shown in the drawings terminating in the bank contacts 209-212, inclusive. Then, immediately upon the energization of the l ne relay 175 the switching relay 178 is energized. Relay 17 8, upon operating, at'its armature 197 opens a point of the circuit of the line relay 175, at the front contact starter .wire to the switch.

armatures 196 and 200" connects the trunk conductors 160 and 163 of the selected trunk line through the windings of the line relay 225 ofthe selector E.

Returning now to the operationof the combination switch F, when the relay 50 energizes a circuit is completed for the relay 62 at armature 67. The latter relay, upon operating, at its armature 111 opens the circuit of the slow acting relay 60, at its armature 112 opens a'point in the-circuit of relay 51, at armature 113 establishes a locking circuit for the relay 58 independent of springs controlled by relay 51, at armature 109 closes the circuit of the relay 51, and at armatures 108 and 110 connects the line of the substation A to the trunk conductors 160 and'163. As was mentioned before, line relay 225 of the first selector E is connected to the trunk conductors 160 and 163. Thus the subscribers line is extended to the line relay 225. The relay 51, upon energiz ng, at its armature 71 closes a point 80 extends the auxiliary startingwire on to the next idle combination switch," at armat ure'81 opens the original energizing circuit of relay 58, and at the front contact of this armature extends the incoming next idle combination hen the calling selector E as above described, the line relay 225 is immediately energlzed over the calling line loop and operated, to complete the circuit of the slow acting relay 226; Upon operating, the latter relay at armature 235 prepares the operating circuits of the selector E and at armature 23-1 places ground upon the release trunk conductor 213 therehy establishing a cult may be traced from ground on the release trunk conductor 213, testcontact 210, test wiper206, back contact and armature. 194, armature '199 and: its front contact through the winding of the switching" relay secondary switch'Q andtl1e combination It willhe understoodthat this holding circuit switch F in;theiroperated?position.

V. I is con ipletedbefore'slow'acting relay 60 line is extended to the H energizes also. holding c rcuitfor the switches C and This holding c1r-' in the combination switch F has. had time to deenergize. Y

It will be noted that'the circuit of the line relay. 225 includes the secondary winding of the transformer of the dial tone machine T; In this manner an'a'udible signal is given'tothe calling subscriber in order to notify him that he may now operate his callmg device; When the calling device isopc erated for the first digit of the desired called subscribers number a series of interruptions case is the digit 5 as the called sub-station A is located in thefifth thousand. The slow acting relay 227 is energized in series with theyertical magnet and upon the first ver-i tical step of the switch shaft when the oils.-

normal springs are operated completes a-cir cuit at itsarmature 236 which extends from ground on release trunk conductor 213, armature 236 and its front'contact, either.-

mal spring 2 14 and its working contact, and" through the winding of the steppingrelay' 228 to battery. Upon operating, relay 228 at its armature 237 establishes a locking circuit'for itself, and at its armature 238 pree pares the'circuit of the rotary magnet 2 18.

is produced 1n the line relay 225 which re-V Shortly after the termination of the vertical movement of theswitcln'the slow acting relay 227 deenergizes and completes the circuit of the rotary magnet 248. ll lagnet 2 13' operates to rotate theswitch wipers one step into engagementwith the first set of contacts in the selected leyel and at its arma ture 2 13 opens the locking circuit of stepa ping relay 228, whichideenergizes' opening the'circuitof the rotary magnet which aa- The further operation of the selector E depends uponwhether its wipers? are associated with an idle trunk line or n'ot.

Assuming that the associated trunk line is busy, there will be a, ground potential present upon the test contact engaged by the test wiper 251 and the stepping relay- 228 will be again energized. Relay 228, upon operating, establishes a locking circuit for locking circuit of the stepping relay'228.

The relay 228 and the rotary magnet continue to operate alternately as long as the switch wipers 250-252, inclusive, are asso- 255257, inclusive,,is the'first idle'trunk line in the selected level. Under'these conditions as soon as the switch wipers of the selector E are rotated into engagement with this set of bank contacts, the switching relay 229 is energized in seriesv with interrupter relay 228 as thecformer relay is no longer short circuited, there being no ground potential present upon the test'contact 256. Relay v 229, upon energizing, at its armature 240 connects ground to the test contact 256 in order to prevent the selected trunk line being V seized by another selector switch, at its armature 241 opens the circuit of the slow acting relay 226, and at armatures 239 and 242 ex tends the incoming trunk lines to the line relay.275 of the second selector E.

;The relay 275 of the selector 4 is-energized over thecalling subscribers line loop and at its lower armature closes the circuit of'the slow. actingrelay 27 8. The latter re lay operates at its lower armature to prepare the impulsing circuits'of the selector E and at its upperarmature places ground upon. the release trunk conductor 261 thereby establishing a holding circuit for theselector E, secondary switch C and combination switch F. This holding circuit may be traced from ground on release trunk conductor 261, test contact 256, test wiper 251,

armature 240 and its front contact, through the winding of the switching relay 229,

armature 243 and its back contact off-normal'spring 244: and its'working contact, and.

through the winding of the stepping. relay 228 to battery. It will be noted that this holding circuit applies ground. tothe release trunk conductor 213' whereby the secondary.

switch 0 and combination switch 1*" are also maintained in their operated positions over the'previously traced holding circuit. It

will be understood that this holding circuit is completed before. the slow acting relay- 226'in the selector E has had time to deenergize.

The calling subscriber may now operate his calling device in accordance with the, p 7

"wire 323 thereby completing a circuit for second digit in the desired number. By this operation the circuit of the line relay 275 of the second selector E will be opened a plurality of times in response to the interruptions in its circuit.

' sending impulseso't current to the vertical pulses theselector E, is stepped into the prop.

er level and it is automatically operated to seek an idle trunk-line therein. When an idle trunk line isfound, which we will-as,

' sume, is the trunk line terminating in bank stepping relay 280.

The relay 275, retracts its armatures a plurality of times thereby contacts 301-303, inclusive, the rotation ofthe selector E is terminated and the switching relay 281 is energized in series with The relay 281, upon energizing, extends the incoming trunk-con- 7.0 ductors to the line coil 310 of the combined line and cut off relay 312 associated with the selected trunk line. The foregoing operations of the-selector E" have all; occurred in response to the second digit of the desired number and take place in a manner similar to the operationof the first selector The line coil 310 of the relay 312 is immediately energized over the calling subscribers line loop in series with the common. relay 320.; The coil 310, upon energizing," operates the armature 324 thereby disconnecting ground 'from the test contact 327 associated with the selected trunk line in'the' banks of the secondary switches and rendering it selectable. Another result of the ;en'- ergization of the line coil 310 is that the armature 316 is operated into engagement with its working contact. The springs 318 do not open at this time. nor is the working contact of 316 brought into engagement with the contact 319. By the operation of'armature 316 ground is placed upon the test contact 302 and a holding circuit is established for the selector E and the previously operated switches. The relay 320 is common to a number of these trunk lines which may be more or less in number depending upon the number of snnultaneouscalls that can be set up. In tne present case, it has been assumed, that the incoming traffic to the group of. lines in L would be commonto 3 trunk lines.

. Relay'320, upon energizing, at its armature 321 places ground upon the starting starting the first idle secondary switch which we will assume, is thesecondary switch C associated with the. combination switch. F. 12.0.

351 opens a point in its short circuiting circuit and also the circuit of relay 338, and at its armature 353 completes the circuit of the V relay 336.

' tacts of the selected trunk line.

Relay 336, upon operating, at its armature 348 brings the test wiper 367 into operative relation with secondary switch C at the sametime disconnecting the test wiper 366, 3.1)31'1112131119 347 prepares'a locking circuit for itself, at armature 350 completes a circuit which includes the switching relay 335 and tliemotor magnet 339 in series, and at itsarmature 349 connects the test wiper 367 to the latter circuit at a point midway between the switching relay and the said motor magnet. The operation of-tlie secondary switch C now depends upon whether its wipers 365-368, inclusive, are associated with the bank con- It' not, there will be a ground potential upon the test contact engagedby the test wiper 367 switching relay 335' will be short circuited and the motor magnet 339 being supplied with direct ground by way of the said test wiper will operate as a buzzer to advance the switch wipers step by step in search of the trunk line in'use. When the switch wipers engage the bank contacts of the selected trunk line which, we will assume, are the bank contacts 325-328, inclusive, there will be no ground potential present upon the test contact 327 and the switching relay .335, be ing no longer short circuited, is energized in Relay 335, upon energizing, at its armature 343 connects ground to the testcontac-t 327, at this'same armature establishes a locking circuit for the relay 336 opens the circuit of the slow acting line relav' 337 at armature 342, at the front contact of this armature partially extends the starter wire 'to'the next idle secondary switch. at armature 341 prepares a point in its locking circuit and at armatures 340 and 345 extends the trunkline in use to the line relay 381 of the combination switch F. The incoming starter wire 323 is completely extended to the nextlav 312. By the operation of armatures 315 arid 317 the line coil 310 is disconnected from the trunk conductors and the circuit of the common relay 320 is opened. The armature 316 is completely attracted so that the springs 318 are opened and the worxing contact of armature 316 is forced into enga ement with the'spring 319. The springs 318 are so adjusted that they do not open until the working contact of armature 316 is forced into engagement with'the spring 319. The provision is made so that the holding circuit of the previously ope-rated switches will be maintained continuously. The two step operation of the relay 312 is due toits mechanical construction as it is constructed in the same manner as the relay 17, which operates at its armature 413 to extend the incoming starter wire 457 to the next idle combination switch, at armature 412 extends the auxiliary incoming starter wire to the next idle combination switch, and at its armature 439 completes a point in a certain chain circuit the purpose of which will be described later. The relay 391 is energized at this time so that the combination switch F may not be started as a finderand to extend the starter circuit to an idle combination switch'which may be operated as a finder.

Referring now to the operation of the" combination switch F when the calling subscribers lineis extended to the'line relay 381, this latter relay is immediatelyener-i gized over the calling line and atits arma-- ture 400 completes the circuit of the slow acting relay 382. The latter relay, upon operating, at its armature 404 prepares the impulsing circuits of the combination switch F, at its'armature places ground upon "the release trunk conductor 373. and at its:

armature 402 completes another circuit for the slow acting relay 391 to. pre vent'its circuit being brbkenbythe deener'gization of the slow acting relay 337' in the secondary switch 0". 1

ll hen ground is placed upon'the release trunk conductor 373 a holding circuit is established which extends by way of the conductor 373 armature 341. and its front contact, through the winding of the switch ing relay 335 of the secondary switch C and through'the winding of the'motor magnet 339 to battery. A branch of this'holding circuit also extends by way of front'contact and armature 343, armature- 348 and its front contact, wiper 367, bank contact 327,

through the windingv of the cut oil? coil 311 of the relay 312 to battery and also totl e bank contact 302. From the Lba-nk contact,

302 the holding circuit for the switches E,

E, C, and 1* is the same aspreviously traced. g

In this manner all the switches their operated positions.

The calling 'subscriber may now operate hiscalling device in accordance Wltllthe third digit of his desired number. 1 A series of interruptions is thereby produced in the circu'itot' the line relay 381 which retracts its armatures a corresponding number of arehcld in times. At the first retraction of its armature 400 an impulse of current is sent overthe following circuit Ground by way of armature 415 and its back contact, armature 400 and itsback contact, armature 404 and its front contact, otf-normal springs 408 and 417',thr0ugh the winding of the slow acting low resistance relay 388 and thence through the winding of the vertical magnet 451 to battery. The above is the circuit over which the first impulse to the vertical magnet is sent.. Upon the firstvertical step of the switch shaft the off-normal springs are shifted and the remaining vertical magnet impulses traverse a different circuit which is the same as the one previously traced except that it includes the off- normal springs 408 and 407 and armature 430 and its front contact, relay 388 being new in an operated position. .Magnet 451 operates to raise the switch wipers 490493, inclusive, step by step until they are raised opposite the desired level of bank contacts in which is terminated the contact set associated with the line of the substation A. The slow acting relay 388,"Wl110l1 is energized in series Wlill" the vertical magnet 451,'maintains its armature attracted throughout the vertical movement oftheswitch and at the termination thereof 'de'energizes and transfers the impulsing cirsuit to the rotary magnet 452.

' The calling subscriber may now operate his calling device for the next and final digit of his desired number. 'Asbefore, an-. 'OtllBfSQIlQS of'interrup'tions is produced in the line circuit .of the line relay 381 which retracts its armaturea corresponding numleer ofltimes; At each deenergization of the line relay 381, a circuit is completed wh ch extendsfroin ground, by way of ,ar

mature 415 and its back contact, armature 400 and its back contact, armature 404 and its front contact, off- normal springs 408 and 407, armature 430 and its back contact, normally closed springs controlled by. armature 438 through the winding of the slow acting relay 389, backcontact and armature 444, and through the winding of the rotary magnet 452 to battery.- Magnet 452 operates to rotate the switch wipers into engagement with the set of bank contacts associated with energized in series with the rotary magnet the line ofthe called substation which, wev

will assume, are the bank contacts 495 498, inclusive, associated with the line of the substation A; The-slow acting relay 389 is 452 and operates at itsarinature 433 to short "circuit the normally closed springs controlled by armature 438 of the test relay 390 so as to provide against premature opening of the rotary magnet circuit while the switch wipersare rotated over busy lines and at armature 432 connects the test wiper491 to the test relay 390. The operation of the ately energized. Relay combination switch F now depends upon whether the substation A is busy or not.

Assuming that the desired line is busy,

there will be a ground potential on the test contact 496 and the test relay 390 is immediately energized. 'Relay 390, upon ener gizing, at its armature 438 opens the rotary magnet circuit, at armature -437"prepares a point in its locking circuit which is conito thelower heavy talking conductor; By.

this latter operation the calling subscriber is given. the usual audible busy signal 111 order to inform him that the called line is inaccessible at the present time. Upon hearing this signal the calling subscriber will replace his receiver upon the switch Ehook thereby initiating the release of the operating switches in a manner which will be described later. 1

It will now be assumed that the line of the substation A is idle when the switch wipers of the combination switch F are rotated into engagementtherewith. Under these conditions there will be no ground connected to the test contact 496 and no circuit will be completed for the test relay 390. Then, following the deenergization ofthe slow acting relay .389, a circuit is completed which extends from ground on conductor 375, armature 437 and its back-contact, lower winding of the switching relay 392, back contact and armature coil 501 of the combined line and cut off re' lay 502 associated with the substation A to battery. The switching relay 392 and the cut off coil 501are immediately operated over this circuit. The coil 501, upon energizing, disconnects the line of the called substation A from'its normal battery and ground connection in the usual manner.

In the combination switch F, the relay 392, upon energizing. at 1tsarinature442 establishes a locking circuit for itself, atits armature 440 places direct ground upon the test contact 496, at its armature 444 opens the circuit of the rotary magnet 452, at the front contact of this armature and at armature 445 completes the signalling circuit of Ringing current s the called substation. 7 now intermittently projected out over the,

A removes his receiver.

tion A the ringcut oif relay 387 is immedi- 387 upon energizing, at armature 426 establishes a locking circuit for itself, at armature 428 places ground upon the conductor extending to the 'lOO called lineuntil the subscriber at substation hen the receiver is removed at substa- 'upontheenergization of the back bridge front contact ofarmat'ure 402 so as topro- V vide against the decnergization of relay 2591 relay 386, atarmatures 425 and 427 opens the ringing c1rcuit and at the front contacts of these armatures finally completes the talk ing connection. The back bridge'relay 386 is. immediately energized over the called subscribers line and serves to supply talking.

battery to the called subscriber. lhe calling subscriber is supplied .with talking bat f the circuit of the line relay 381 is opened and this relay deenergizes and opens the cir-' cult of 1ts associated slow acting release relay 382.7 The latter relay, upon deene-ia gizing, at armature 404 completes the ,circuit ofthe release magnet 450 of the combination switch F, at armature 403 re-moves ground from the release trunk conductor 373, and at armature 402 opens the circuit of the relay 391. Magnet D operates to restore the combination switch F to nor mail. The deenergizat-ion of relay 382 also removes ground from the conductor 375 whereby the locking circuit of thei'ing cut or relay 387 and the switching relay 392 aer opened and these relays'deenergize. The deenergization of 'the slow acting relay 391. again conncts the incoming starter wires to the combination switch F.

When ground is removed fromthe release trunk conductor 37 3 the circuits of the re- L'vs 335 and 336 in the secondary switch C are opened and also the circuit-oi? the cut at; coil 311 in the trunk circuit. The relays 335 and 336, on dee-nergizing, restore the circuits of the secondary switch tonormal. The deenergization of the cut off c'oil 311 restores the connectioniofrthe line coil 310 with the trunkconductors. The holding circuit of the'switching relays 9.81

and 229 'of the selectors E and Enre also opened by the removal of ground from the release trunk conductor 373 and these relays dccnergize thereby complet ng the circuits of their respective release magnet-s 283 and 245. In this manner the selectors E and.

in are released. v

' lly the removal of ground from release trunk conductor 213 the holding circuit of the switching relay 178 in the secondary switch Cjand the relays 62, and 58 in the feonibination switch F are opened. he deenergization of the relay 17S serves to restore the circuit connect-ions of the secondary switch G to normal. thedeenergi zation of the. relays 50, 5S and 62 the circuit of; the release magnet 117 of the'co-inbina'atioi switch F is completed and also certain" other circuitsin this switch are restored'to leased.

normal. By the operation of the release magnet 117' the combination switch F. is re The, removal of ground fronithe eleas'e and cut'ofli relay 17:whereby' the line coil 1! is again connecte d to the line of the sub: stationA. In the above manner the release of the connection takes place upon the calling subscriber replacing" thelswitchhoolil trunk conductor also opens thecircuit the cut Of'CO ll 16 of the combined line his receiver upon Having described the manner in which a 7 connection is setup between two subscribers certain special provisions and-circuit a rrangement will now'be noted and explained.

'It will be remembered that when the conibinat-ion switch Fwasoperated as a finder that'the test wiper 152 was brought into operative relation with'theswitch and the test wiper 151 -disconnected. This provision is made so that there will be 5 interference when the switch F is operated as arfinder andwhen it is operatedas a connector. I

- It will now be'in order to explain how the various combination switches are prevented i i from being operated as finders while their associated secondary switches are standlng with their wipers associated with busy trunk 111168. In order todesonbe this operation, it v s ubwill be assumed thatwhen; the callin scriber at substation A 'renioves' his receiver that the combina-tion switch F is idle and that its associaltedisecondary switch G "has its wipe-rs standing in engagement with a busy [trunk line. Under these conditions there will be a ground potential present upon the test contact engaged by the test wiper 206. j A circuit is now completed eX- tending from the grounded test contact, test wiper 206, back; contact and armature 194,

armature 199' and its back contact, 1 armature I 195. and back contact; aiunaturef186 and its'back contact conductor lol 'a-ndthence through the winding 0u1ere1ay59 in the switch F to battery; The relay 59 is energized overthis circuit and,'upon operating; completes apo-lnt 1n a certain chain on- "c uit, which will be described later, at armature 99 and at armature 100 disconnects the incoming starter wire 38'fromthe com'binationswitchF and extends it by way of the conductor 44' tothe next idle combination I switch. Thus, when the calling subscriber removes his receiver, the combination switch F will not be started as the starter wirehas 3 been diconneot'e d' froi'n this switch and extended on. It will be noted that t-heenergizatio-n of the relay 59 hasinoefiect upon the auxiliary starter wlre 40 w'li'icli st ll-re mains connected to the switch F; 1

\Vhen all the combinationswitches ofthc group are busyeither tor the reasonot their being used in c'onnectlons-or because their associated switches are standing in engage ment with abusy trunk line means mustbe provlded sogthat any combination switch may be started as a finder which is not-being usedgin a connection regardless of whether .or not its secondary switch as associated with a busy trunk line. Inorder to do this, when all the combination switches become busy for the reasons stated above, the aforementioned chain. circuit'is completed and the which is shown on the right of the figure .Itwill be noted that the ordinary starting loop circuit is controlled by two relays in each of the-combination switches, the relays '51 and 59 in the combination switch F for example. This loop is so arranged that the incoming starter wire is extended either when the combination sw tch becomes busy or because its secondary switch is not associated with an idle trunk line bytherelay .51 in the former case and the relay 59 in-the latter case. The auxiliary starting circuit is only underithe control of armatures on the relays, such] as 51 in the'combination switchesso that when this starting loop c'ir cuit is in use :any "combination switch may be-started as long as it is idle regardless of whethervits secondary switch is associated with an idle-trun'k lineor not. ii i v 1 When one of, the combination switches is started whose associated secondaryswitch is standing with its wipers in engagement with a busytrunk line its secondary switch is I caused tolhunt tor and connect with an idle 45 trunk line, In order tofdescribe this operation it will be assumed that the combination switch F .is started over the auxiliary starting loop and that theiswitch G has its wip- .ers associated with a'busy trunk line. "It will beremembered that whenthe switch .F is startedground is placed upon release trunk conductor 162 by the operation of the slow acting relay This causes' the energization of the line relay 1750f the'secondary switch C. Relay 1175, upon energizing, at its armature 185 completes a circuit whichrincludes the switching relay 178 and the motor magnet 17 9 inseries, at its armature 186 disconnects the test wiper 206 from the conductor 161 and at the front contact of this armatureconnects theisaid test wiper to ta point midway bet-ween the switching relay randrthe said motor magnet, As the switch wipers rof the secondary switches vare before,

ypende'd claims.

standing in engagement with a busy trunk line, there will be aground potential present c upon the test contact engaged by thetest 1 w iper 206, the motor magnet 175 being sup;

plied with direct groundlby way of "the said '70 test wiper will operate as a buzzer to ad; Vance the switch wipers step bystep in search of an idle trunk line. ,When the idle trunk lineis 'found, there will be no ground potential on the test contact engaged by further operation of :thehcor'nbination switch F and the secondary switch C takes place in the same manner as was described herein- It will be noted that whengroundisplaced on the releasetrunk conductor 162 to start the secondary switch C-that the 'relay1'76 is 1 short circuitedl; This is to prevent this re lay from energizing in case ground is placed .upon thestarter wire 201 in order to start a secondary switch as a finder. Immediatelyupon the energization of the switching'relay 178 the starter wire 20 1 is extended to an idle second ary switch which is thereuponautomatica-lly operated, as before described, to find the seized trunk line,

The starting circuit for starting the secondary.switches'such as C and C as finders is an ordinary starting loop wherebyaplu' 'rality of the switches may be started 'simu'l- I taneously.

The features of theinvention 'havingvibeen described and ascertained, what'is considered to be new and desired to have protected by Letters Patent will be pointed out in the ap- What I claim as my invention'is: 1." In a telephone system, a telephone line,

a plurality of finder s'witcheshaving access to said telephone line, a line switch linked with each of said 'finder' switches, trunk lines accessible to said line switches, means controlled from said line for starting an idle one of-said finder switches to search for-said line, and means operative whereby only an idle finder switch is started whose associated'line switch has its wipers in engagement with an idle one of said trunk lines; V V

r 2. In a telephone system, a group of finder switches, telephone lines/accessible thereto,

a secondary'switch linked with each of said finder switches, trunk lines accessible to said secondary switches, wipers for each of said secondary switches always standing in engagementwith some one of said trunk lmes,

means for making some of said trunk lines busy, means controlled from one ofsaid-cal'ling lines for starting an idle one of said finder switches, and means for preventing the starting of this 'finder switch it its as sociated secondary'switch has its switch wipers' associated with a busy one of said trunk lines. I

3. In a telephone system, a. group of finder switches, telephone lines accessible thereto, a secondary switchlinked with each finder ofsaid group, trunk lines accessible to said secondary switches, means for making some;

of saidtrunk lines busy, each of said finder switches being normally first'choice to a group of said telephone lines, means controlledfrom a calling one of'said lines for starting the finder switch normally assigned to it if said switch is not in use,'and means for preventing the calling line from starting said switch even if idle if its associated secondary switch is associated with a busy one of said trunk lines. i 4;,In a telephone system, a plurality of finderswitches, a plurality of lines normally divided into "groups for the purpose of starting said finders,therebeing a finder assigned to each group oflines, means whereby a calling line in any one "of said groups can start the finder assigned to such group, a starting loop circuit for starting said finder switches whereby when one of said finders normally assigned to a group connects with a calling line in that group the starting circuit is extended to the next switch, a secondary'switch linked with each finder switch, trunklines accessible to said secondary-switches, and means for extending said starting loop to the next finder each time the associated secondary switch is in engagementwith a busy one of said trunk lines.

In a telephone system, a plurality of telephone linesgarrangedin groups, a plu rality of finder switches" having access to said lines, there being one of saidfinder switches normally assigned to each of said groups, a starter wire circuit to control the starting of the switch'ofasucceeding group i it the finder assigned to the group in which the callforiginates is busy, means to extend thesaid'starter wire to a succeeding switch when a calling line is. seized, a secondary switch associated with each finder switch of said plurality, trunk lines accessible to said secondary switches, wipers for said secondary switches always associated with some one of said trunk linesfmeans for making any ofsaid trunk lines busy, and'meansjoperative whcnjthetrunk line associated with one of said secondary switches becomes busy for extending the starter wire of the associated finder switch to the succeeding switch. 7 y a 6. In a telephone system, telephone l1nes,.

automatic switches having access to said telephone lines, a secondaryswitch linked with each of said automaticswitches, two groups of trunklines accessible to said secondary switches, means controlled from a callingone of said telephone lines for caus ingone of said automatic switches to opcrate as a finder tofind said line, means operative to cause said secondary switch to:

seize one of said trunk lines, means-operated by another calling subscriber for caus-: ing said secondary switch to find a trunk line used by the calling subscriber and'tor thereafter operating the associated auto matic switch as a connector to extend a connection to one of said telephone lines.

7. lnya telephone system, telephone" lines divided into groups, finder switches having access to said telephone lines, a starting loop' circuit whereby a. plurality of finder switches may be started in search of a plurality of calling lines simultaneously means 'for extending the starter loop on as each switch becomes busy, secondary switches, trunk'lines accessible to said secondary switches, wipers for said secondary switches always associated with one of said trunk I lines, 'means'itor eXs tending thestarting'loop .to the next finder if the associated} secondary switchhas-its wipers resting on a busy trunk line, and a second starting loop circuitwhich is con trolled only by the finder switches becoming busy and which is independent of whether the associated secondary switches are stand ing on an idle trunk or not;

8. In a telephone system, telephone lines" becoines' busy, secondary switches. trunk 1 lines accessible to said secondary-switches, wipers for said secondary switches always" associated with one of saidtrunk lines,.m'eans for extending the starting loop 'tothe next finder if the associated secondary switch has itswipers resting on a busy trunk line, a secondstarting loop circuit, which is controlled only by thefindcr switches becoming busy and which is independent of whether the associated secondary switches are standing on an idle trunk or not, and means efiective'when the first starting loop circuit is completely closed for switching the incoming starter wires onto said second loop circuit; 1 1 r 9. Iii-a telephone system, telephone lines,- agroupot finder switches, a starting'loop circuit wh'ereby an idle one of said finder switches may be started {TO Ill a calling one linked with each of said finder switches, trunk lines accessible to ,said secondary switches, a set'ot' w pers tor each of said secof said telephone lines, a secondaryswitch ondarv switches always associated with one V of said trunk lines, means for making some of the said trunk lines busy, means operative when the wipers of one of said secondary IQI switches are associated with abusy trunk associated finder switch on to the nextfinder,

pleted,forV-bringing'said second loop in to, operativezrelation with said lines whereby 7 ing switch while the-first switch is operated V line for extendingthe starter loop in the a second starter loop controlled, only by the said finder, switches becoming busy, and ineans'operative when said, first loop is co-ma pluralityo-ffinderswitches may be. started simultaneously over said second starting .,-loo.p circuit.

10. In a telephone system, a two way link circuit having 'an automatic progressively ,movable, switch at each end thereof, means effective when a call is extended over said link in onedirection for operating the switch at one end as a finder or backward selecting switch and the switch at the'other' end as alforward selecting switch, and means ettective' when a call is extended over said link in the other direction for operating the second switch as a finder or backward selectas a forward selecting switch. I

.li'ne, two'progressively movable switches at opposite *ends of said trunk line and constituti-ng the only terminals thereof, and means including said two switches for extending connections over said trunk line in either direction. I i i V r .12. In a telephone system, a. two way trunk line, two progressively movable automatic switches, one at each end of said trunk line, means including both of said switches for extending a connection over said trunk line-inone direction, and means including "the same twoswitchesfor extending a connection over said trunk line in the opposite direction. v

13. In a telephone system, atwo way trunk line, an automatic switch at each end of said trunk line, means for 'operating one switch as, a backward selecting. switch and the second switch as'a forward selecting switch;

to extend a connection over said trunk line in one direction, and'means for operating the said second switch asa backward selecting switch and the first switch as a forward selecting switch to extend a connection over said trunk line in the opposite 'directioin 14;, In a telephone system, atelephone line, a group of combination switches having accessto said line, an auxiliary switcl individual to each combination switch, trunk lines accessible to [saidauxiliaryswitches, means controlled from said line for startingan idle "one of said combination switches to search for said line, and means for starting the first idle combination switch whose associa=ted auxiliary switch is in engagement withan idle one of said trunk lines, pro- 11; In a telephone system, two way trunk switches together.

line, a group of combination switches having access to said line, anauxiliary switch. in -t dividual to each combination switch, trunk lines accessible. to said auxiliary switches, means-controlled from said line for starting an idle one ofsaid combination switches to search for said line, and means for starting an idle combination switch whose' associated auxiliary switch is in engagement with a busy one, of said trunk lines-providing no auxiliary switch is in engagement,

connectorsw-itch and finder switch, a combination lineswitch and finder switch, and a trunk line" permanently linking said 18. Ina telephone system, agroup of lines, link circuits for extend-ing'said lines when calling, each link comprising a line finder and a hunting switch, trunk lines accessible to a call on one of said lines for starting an idle finder, and means for preventing any to said hunting switches ,*means responsive ioo 19. In a telephone system, a group'of lines,

flink circuits for extending said lines when calling, each link comprising a 'line finder and a hunting switch, trunk lines accessible to said hunting switches,'and means responsive to a call on one otsaid lines for starting the first-brie of said finders which has its paired hu-ntingsw tch standing on an idle one of said trunk lines. I

20. In a telephone system, a

device terminating a trunk line and having movable wipers, means for extending a telephone call through said switch over said trunk line in either direction, a condenser in a, talking conductor of said switch, means for including said condenser n the talking connection in a call in one-direction,and

switching means for excluding said condenser from the I talking C(D-D-ILQOtlOl-i in a call-in the other (ll?- rec'tion. c 7 v 21. In a telephone system, a 'SWllZCl-lllig desciibers when alcall is extended through said switch in one direction, and means for disconnecting said current supplying means xvice terminating :a .trnnk line and having whena call is extended through said switch lines, means controlled'from a'calling one of said telephone lines for starting said automatic switch tooperate as a finder to findsaid calhng line and tor causing said auxiliary switch to select van idle one of said trunk lines, means operated by a second calling subscriber for start ng said auxiliary switch to operate as a finder to find the trunk line used by said second calling sub:- scriber and for operat ng said automatic switch as a. connector to extenda: connection to one of said, telephone lines,- and means for disabling the said second means when said automatic switch has been started as a finder. v

24. In a telephone system, telephone lines,

an automatic switch having access to said telephone lines, trunk lines, an auxiliary switch permanently linked with said automatic switch having access to said trunk lines, means controlled from a calling one of said telephone lines for starting said automatic switch to operate as a finder to find said calling line and for causing said auxiliary' switch to select an'idle one of said trunk lines, means operated by a second calling subscriber for starting said auxiliary switch to operate as a finder to find thetrunk line used by said second calling subscriber and 'for operating said automatic switch as a connector to extend a connection to one of said telephone lines and means for disabling the said first means when'said auxiliary switch has been started as a finder.

25. In a telephone system, telephone lines, an automatic switch having access to said, telephone lines, trunk'lines, an auxiliary switch permanently linked with said auto matic switch having access to said trunk lines, means controlled from a calling one of said telephone lines for starting said automatic switch to operate as a finderto find said calling line and for causingsaid auxiliary switch to select an idle one of said trunk lmes, means operated by a second callingsubscrlber for starting said auxlhary switch to operate as afinder to'find the trunk line used by said secondcalling subscriber and for operating said automatic switch as a connector to extend a connection to one of said'telephone lines, and means for preventing either of said switches, from being a line switch. 1

started 'as a 'finderwhile the other switcliyis" in use as a finder. a e

In a telephone system, acombination line switch and finder switch terminating a link, trunk lines accessible to'sai'dcombinartion switch, a startinglc'ircuit including a relay controlled over said trunk lines for starting said combination switch to operate a finder, a second starting circuit controlledover said link for starting said switch to operate as a line switch, and means for 1 short circuiting said relay when said switch is'startcd as a i ine'switch'forpreventing said switch from" being started as finder.

27.131 telephone systemfa combination line switch and finder switch terminating a linlr, trunk lines accessible to said combina tion switch, a starting circuit including a relay controlled over said trunk lines for starting said combination switch to operate as a tinder, a" second starting circuit controlled over said linlcfor starting said switch to operate as a line switch, and means for opening said second starting circuit, a

when said switch is started as a finder 'for preventing said switch from being started as 28. In a telephone through said finders,- an auxiliary starting circuit extending through said finders, two transfer relays in each finder, ,multiply connected contacts on each pair of relays in cluded insaid main starting circuit, and contacts on only one relay of each pairincludedin said auxiliary'starting circuit-f 29. In a telephone system, a group of finders, a main starting circuit extending throughsaid finders, an auxiliary starting circnit'extendmg through said finders, two

transfer relays in each finder,"multiply connected contacts-on each pa1r of relays insystem, a group of" finders, a main startmg c rcuit extending,

cluded in said main starting circuit, contacts 1 I on only one relay ofeach pairincluded in iliary starting circuit being normally 1m 5 effective, 7 a chain circuitincluding contacts on each pair of relays,and means controlled over said chain circuit for rendering said auxiliary starting circuit efiective 80, In a telephone system, a combination finder andv connector switch having two test wipers, means includingone of-said wipers for testing a called line when saidswitch is used as a connector, and means including the other of said wipers for findinga calling line when said switchisused asalfinder.v

8 1. In a telephone system, a combination I I finder and connector switchj'having a con-i nector test wiper normally in operative relation with said switch and a findertestfwiper normally in inoperative relation with said switch, and means tor substituting-the second wiper for the first when said switch is used as a finder. u 1

said auxiliary starting circuit, said aux-[l 32. In a"conibinati0n finder and connector switch, aconibinat on testing and stepping: relay for testing called lines and for finding calling lines;

V 33. Ina;combination:finderand connector switch, arelay, a testing circuit for testing;

called lines and a second testing circuit for V finding calling lines, both saldclrcuits 1nlines, a combination finderswitch and connector switch; having: access thereto, selector switches for use in completing calls outgoing from said group, selector bank terminals for-use in coinpletingcalls incoming to said group, and free hunting non numerical switching means for connecting said combinationswitcli with one of said selectors to extend an outgoing connection, and for con.-

necting said combination switch With said selector. bank terminalsto extend an ineoinmg connection.

In itness Whereofi'I hereunto subscribe iny name thisu6t-lr day of October, A. D.',

' JOHN E. GARDNER.

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