US1990644A

US1990644A - Telephone system

Info

Publication number: US1990644A
Application number: US582110A
Authority: US
Original assignee: CENTRAL REPUBLIC BANK AND TRUS; CENTRAL REPUBLIC TRUST Co; MILTON S FRIENDLY; OSCAR N FRIENDLY
Current assignee: CENTRAL REPUBLIC BANK AND TRUS; CENTRAL REPUBLIC BANK AND TRUST Co; CENTRAL REPUBLIC TRUST Co; MILTON S FRIENDLY; OSCAR N FRIENDLY
Priority date: 1931-12-19
Filing date: 1931-12-19
Publication date: 1935-02-12
Anticipated expiration: 1952-02-12

Description

Feb- 12, 1935. H. M. FRIENDLY TELEPHONE SYSTEM Filed Dec. 19, 1951 4 Sheets-Sheet 2 Feb. l2, 1935. M, FRlENDLY 1,990,644

TELEPHONE SYSTEM Fued Dec. 19, 1951 4 sheets-'sheet s In Ver/for- Friendly-Deceased Feb. 12, 1935. H. M. FRIENDLY 1,990,644

TELEPHONE SYSTEM Filed Dec. 19, 19:51 4 sheets-sheet 4 I n ven f o r H. M. Fr/ndly Jeu-eased Ml'lon 5. Friend/y and enf /epublfcan/f us [obra-afar.:

Patented Feb. 12, 1935 UNITED STATES PATE NT OFFICE TELEPHONE SYSTEM Applicationv December 19, 1931, Serial No. 582,110 27 Claims. (Cl. 179-27) His present invention relates in general to telephone. systems, and more particularly to such systems as may be of the automatic or semi-automatic type.

One of lthe objects of the present invention is to provide trunk lines which may be employedfor a dual purpose.

Another object is to provide means for enabling trunk lines extending between various groups ci? automatic switches in one exchange or from one -exchange to another to be used inthe usual manner and also to permit these trunk lines to be employed for special calls.

A further object is to consolidate special groups of trunk lines into a single group to secure greater eiiciency. 1

` A still further object is to provide mechanism by which it is possible to secure greater trunking efilciency by enabling a call to proceed from a calling to a called telephone subscriber over a route involving a greater number of stages ot selection than is called for by the called subscribers number.

Still anotherl object is to accomplish this result without unduly increasing the complexity of the mechanism.

Still another object is to provide means for calling operators or other special numbers over trunk lines that would be employed in the regular course of establishing a connection between two subscribers.

There are other objects of his invention which together with the foregoing will be described in the detailed speciiication that is to follow, taken in conjunction with the accompanying drawings and forming a part thereof.

Referring now to the drawings, Fig. 1 is a schematic diagram illustrating the trunking arrangements for various connections in an automatic telephone system employing his invention;

Figs. 2 and 3 illustrate by means of the usual conventional diagrams suiiicient of the apparatus in circuits employed to illustrate the manner in which trunk lines may be employed for`a dual purpose according to his invention;

Fig. 4 shows typical selector switches which may be employed in the system illustrated in Figs. 2 and 3 to extend a call to various subscribers.

Referring now more particularly to Fig. 1, the reference characters A, A1, A2, D, C, F, G, H, and I represent telephone instruments of various automatic telephone subscribers of any usual or well known type. The reference Vcharacter M designates a manual telephone of any usual or well known type. The lines of the telephones M,

A, A1. and A2 all terminate at their associated exchanges in line switches LS, LS1, LS2 and LS. These line switches may be of any usual or well known type. The line ,switch of the manual telephone M has access to trunk lines extending to a repeater R2 and thence to an incoming selector Q1*v at another exchange. The repeater Rn may be of any usual or well known type though in the present instance he has illustrated a repeater of the type in general use in Strowger step by step automatic telephone systems. The incoming selector Q3 is also of the Strowger type slightly lmodiiied in accordance with his invention by the additon of a normal level of bank contacts and the provision that the switch may rotate without first moving vertically. The trunk lines accessible to-the incoming selector Q3 extend to other selectors P3 which are of the usual Strowger type commonly designated as Powell selectors. The trunk lines extending from the selectors P3 extend in the present instance to connectors D9 wherein access is obtained to subscribers telephones such as F. The trunk lines terminating in the normal level of incoming selectors Q3 may extend to operators positions such as the positions of the toll recording operators indicated as O. The lines o f the subscribers at automatic stations A terminating in line switches such as LS1 have access through these line switches to iirst selectors of the usualv Strowger type such as P2, of which only four contacts of each level are shown by the four vertical rows oi ten contacts each to the 'right of the wiper of P2. It is to be noted that the trunk line extending through the repeater R2 to the incoming selector Q3 is also accessible from the second level of bank contacts of certain of the rst selectors. The lines of the telephone stations such as A1 terminate in line switches L82 and have access through these line switches to rst selectors such as P16. The reference characters P1'7 and'P13 designate ordinary selector switches while the reference character D19 designates a group of connector switches. 'The lines of the subscribers such as A2 terminate in line switches LS3 at a local or sub-exchange. The line switches LS3 have access to trunk lines extending through repeaters such as R5 to incoming first selectors Q at the main exchange. The incoming first selectors Q are provided with a normal level for bringing about the extension of a call by way of the normal level to an incoming second selector such as P13 at another exchange. The trunk line extending through tli'e repeater R5 may also be accessible as in the present instance froml the fifth level of the first selectors such as P2 permitting the calls extending from this group of first selectors to extend through the sub-exchange and thence to the exchange at which the call subscriber is located when the digit 5 is called. The various incoming selectors designated. with the reference character Q indicates incoming switches which are provided with a normal level. The reference character P designates the usual type of Strowger selector switches.

In order to give the broad understanding of his invention he first describes typical calls from automatic sub-station A to various call subscribers. He iirst assumes that the subscriber at substation A desires to call the subscriber at substation G whose number is 24641. The removal of thereceiver at sub-station A brings about the operation of the line switch LSI to extend the calling line to an idle first selector P. The operation of the calling device at the station in accordance with the digit 2 brings about the selection of a trunk line extending through a repeater Rs to an incoming. second selector Q1 in the exchange in which the subscriber at substation G is located. The operation of the calling device in accordance with the next digit 4 brings about an extension of the calling line to an idle third selector P10, the next operation of the calling device for the digit 6 brings about the operation'of the selector P10 and the extension of the calling line toan idle connector D11. The remaining two digits 41 serve to select the called line. When the calling subscriber at sub-station A desires to call -the subscriber at sub-station H whose number is 53321, the following operations occur: The selector P2 is operated to the 111th level in accordance with the rst digit and a direct trunk line in the fifth level leading toward the wanted exchange of station H is selected extending to the incoming second selector P12 and thence by way of this switch through the selectors P14 and connector D15. In the event that the direct trunks are busy, a certain other or indirect trunk at the end contact of the ilith level is selected extending from first selector P such as the one extending to the repeater R'1 this operation of dialing the digit 5 for a call to the subscriber at sub-station H brings about the selection of the trunk line extending through the repeaters R" at the exchange of the calling line and the repeater R5 at the sub-exchange to an incoming selector Q. The seizure of this trunk line brings about the automatic operation of the selector Q on its normal level to select a trunl-r line terminating in the incoming second selector P11. The remaining dialing operations bring about the establishment of the connection with the subscriber at substation H in the usual manner through selectors P13 and P1* and connector D15. It will be seen that this call extends by way of the trunk line through the sub-exchange of the subscriber at sub-station A2 and that the selector Q is operated automatically to trunk this kind of a call through the main exchange overa different path than that obtained in a previously established connection from A to H. This alternative trunking route may be advantageously employed to inincrease the etlicieney of the trunking system.

When the subscriber at a manual telephone M desires to make a call, which call must be made by an operator, and removes his receiver, the operation of the line switch LS extends the calling line through the repeater R2 to an incoming selector Q1. This operation causes the Selector Q11 to rotate on its normal level to extend the calling line to an operator O who may answer the call and establish Ache'connection as desired. If thisoperator is employ'ed as a toll recording operator or a complaint operator, it may be desirable to provide means by which the automatic subscribers such as the one at sub-station A have access to trunk lines extending to this position. This is accomplished by designating the tenth or O level of the rst selectors for this use. the selector Pz is operated into the tenth level the subscribers line is extended through the incoming selector Q3 to the operator's position O. Other operators positions such as the one at E may be selected in a similar manner by extending the trunk line C to the proper level of selectors which may be employed for the handling of these calls, and an alternative arrangement is illustrated for the trunk line C by means of the switch K whereby the operator's position E is rendered accessible from the eighth level of the third selectors such as P5 or the fifth level of second selectors such as P1. This operator's position would then be accessible upon dialing 45 or 438, depending upon the position of the switch K. The selector Q4 is also accessible from the second level of certain'groups of first selectors P2 and in this instance when a call is extended through the first selectors the incoming selector Q4 would operate in the usual manner. Thus it will be seen that the arrangement described permits trunk lines to be employed for a dual purpose in a larger group than heretofore. The usual practice in exigencies oi' this character where similar conditions are to be met involves the use of a separate group of trunks extending to each operator's position. By his invention, the trunk lines may be consolidated into one group securing greater traflic emcency and considerably reducing the expense. Furthermore, the invention may be employed to trunk through another exchange in a roundabout manner which ordinarily could not be accomplished in the ordinary use of a telephone system without the use of a device such as a director or translator. His invention also permits manual telephones to be employed and terminate at an automatic exchange and have calls from these telephones handled by an operator.

Having briey described the general process of setting up various calls in an automatic telephone system of his invention, he now explains the detailed circuit arrangements and operations by which this is accomplished.

v Referring now to Fig. 2, the reference character M in the upper lefthand corner thereof designates a manual telephone of the usual or well known type. The line from the manual telephone terminates in a line switch LS. 'I'his line switch is of the usual or well known rotary type and is provided with a line relay 101, switch- 'ing relay 100, motor magnet 102 and wipers 109 to lll inclusive. Motor magnet 102 serves to step the switch wipers into engagement with bank contacts which are connected to trunk lines extending to repeaters such as R2. The lines of the automatic subscribers such as at sub-station A terminate in line switches LS1 of a type similar to the line switches LS. The telephone station A is of the usual automatic type. The line switches such as LS1 have access to trunk lines extending to first selectors such as P2. The first selectors such as P2 are of the usual and well known Powell type being provided with a ver tical magnet 120, rotary magnet 121, release When magnet 122 and control relays 115 to 119 inclusive. The selector P2 is also provided with wipers 137 to 139 inclusive which have access to bank contacts on ten levels. The trunk lines terminating in the bank contacts accessible to rst selectors extend to other selectors as may be seen in Fig. 1, and also to trunk lines extending through repeaters such as R2 to incoming second selectors such as Q3 (Eig. 3) located at a diiferent exchange. The repeaters such as R2 are generally of the same type as those ordinarily employed in automatic exchanges have the controlling relays 150 to 154 inclusive and 158. In addition the repeater R2 is provided with

relays

155 and 156 which have a special function in accordance with his invention as will appear.

The incoming second selector Q3 is of the usual and well known type of Strowger switch with the exception that it is provided with a normal level of bank contacts accessible to switch wipers 225 to 227 inclusive. The selector Q3 is also provided with a vertical magnet 206, rotary magnet 207 and a release magnet 208, in addition to the controlling relays 200 to 205 inclusive. The bank contact accessible to the switch wipers 225 to 227 inclusive on the normal level extend to operators position such as O. On the other levels they may extend to third selector switches such as the selector P3. Selector P3 is of the usual step by step type in common use. The circuits at the operators position O may be of any usual or well known type. In certain instances there may be a. large number of operators having different functions and it may be desirable to select between them. I'his can be accomplished by the provision of a selector such as P23 accessible from the normal level of bank contacts of the incoming selector such as Q3. The selectors P23 as well as the selectors P22 are similar to the selectors P3 previously described.

Having briefly described the circuits and apparatus necessary to illustrate his invention, he now explains their detailed operation. For this purpose, he assumed that the subscriber at the manual telephone M desires to make a telephone call. In order to accomplish this result, his line must be extended to an operator at the operators position O. This result is brought about in the following manner. When the receiver is removed at the manual telephone end, the two line conductors of the calling end are bridged and there is a circuitJ completed which extends from ground by way of back contact and armature 104talking conductors of the calling line armature 103 and its back contact and relay 101 to battery. The relay 101 is energized over this circuit and operates to establish a circuit for the switching relay at armature 108 in series with the motor magnet 102 and an armature 107 connects the'test wiper 109 to the above circuit at a point midway between the switching relay and the motor magnet. If the trunk line with which the switch wipers 109 to 111 inclusive is busy4 there will be a ground connected to the bank contact engaged by the switch wiper 109. The switching relay 100 will be short circuited and the motorrnagnet 102 will be operated intermittently to advance the switch wipers 109 to 111 inclusive into engagement with an idle trunk as designated by an absence of ground on the test contact. It will be assumed that this trunk line is the one terminating in the bank contacts 190 to 192 inclusive. When this occurs there will be a circuit effective for energizing the switching relay 100 in series with the motor magnet 102.

The switching relay upon operating, opens a point in the test circuit at armature 105momentarily connects ground to the test contact 109 at the front contact of this armature, at the same time preparing a holding circuit for itself, and at

armatures

103 and 104 disconnects the circuit of the line relay from the calling line and extends the talking circuit of the calling line by way of the front contacts of these armatures, wipers 110 and 111, bank contacts 191 and 192, relay 155, normally closed springs controlled by armatures and 161 of the repeater R2 to the upper and lower windings of the line relay 151. The line relay 151 is immediately energized over the above circuit and operates to establish a circuit for the slow acting relay 152 at armature 163 and to place a bridge across the trurik conductors and 181 at armature 164. It will be noted that the slow acting relay 155 is energized in series with the line relay 151. The relay 155 upon operating serves to complete a circuit for the supervisory lamp 157 at armature 174 to complete a circuit for the slow to operate relay 156 at armature 175 and to connect ground tothe trunk conductor 180 at armature 176. This latter operation completes a circuit which extends from ground by way of armature 176 and its front contact trunk conductor 180, armature 211 and its back contact upper winding of line relay 201, and upper winding of differential relay 202 to battery. Relays 201 and 202 are energized over this circuit. The operation of the

armatures

214 and 215 of the relays 201 and 202 of the incoming selector Q3 serve to complete a circuit which extends from ground by way of armature 214 and its front contact armature 215 and its front contact, resting contact of ofi normal spring 217 and said spring, and relay 205 to battery. The relay 205 is energized over this circuit. Another result of the operation of the armature 214 is that there is a circuit completed for the slow acting relay 203. Slow acting relay 203 opens a pointv in the release circuit at armature 219, prepares a circuit for the vertical magnet 206 at the front contact of this armature, and at armature 218 prepares circuits for the rotary magnet 207 and the switching relay 200. The relay 205 is energized to complete a circuit for the rotary magnet at armature 223. The rotary magnet 207 is energized to advance the switch wipers 225 to 227 inclusive into engagement with the rst set of bank contacts. At the rst rotary off. normal step of the switch the rotary off normal springs RS are closed, thereby preparing a test circuit for the test wiper 225. If the rst trunk line engaged by the switch wipers 225 to 227 inclusive is busy there will be a ground potential present upon the bank contact engaged by the wiper 225 and there will be a circuit completed extending by way of armature 210 and its back contact, back contact and armature 221, rotary off normal springs RS and relay 205 to battery. The relay 205 will be energized over this circuit to establish a locking circuit for itself at armature 222 and to complete the rotary magnet circuit at armature 223. The rotaryv magnet 207V will operate to advance the switch wipers another step into engagement with the next set of bank contacts and to open the locking circuit of the interrupter relay 205 at armature 221. The alternate operations of the interrupter relay 205 and rotary magnet 207 will continue until the switch wipers 225 to 227 inclusive are brought into engagement with the set of bank contacts associated with an idle trunk line.

In the repeater R the relay 156 is energized after a short interval of time to attract its arma,- tures, thereby establishing a locking circuit for itself at armature 177 and at amature 178 short circuiting the relay 155. The relay 155 is deenergized after a short interval of time to retract its armature 176, thereby opening the previously traced circuit for relays 201 and 202 in the incoming selector Q2. 'I'hese relays are not deenergized, however, for the reason that a new circuit has been established for them by the placing of a bridge across the

trunk conductors

180 and 181 by the operation of the relays 151 and 152 in the repeater R2. It should be noted at this time that when the relay 152 was energized as previously described, a holding circuit was established for the switching relay in line switch LS. This bridging circuit for the energizing of the relays 201 and 202 in the selector Q3 may be traced from ground through the lower winding of the diierential relay 202, lower winding of line relay 201, back contact and armature 212, trunk conductor 181, front contact and armature 164, righthand winding of an impedance relay 158, normally closed springs controlled by armature 162, winding of electropolarized relay 154, normally closed springs controlled by armature 169, front contact and armature 166, trunk conductor 180, armature 211 and its back contact, upper winding of line relay 201, and upper winding of differential relay 202 to battery. Upon the establishment of this circuit and after the deenergization of the relay in the repeater R2 the differential relay 202 retracts its armature while the armature 214 of the line relay 201 is maintained attracted, This result follows for the reason that the current flow through both windings of the diierential relay 202 now oppose each other. 'I'he retraction of the armature 215 opens the original circuit for the interrupter relay 205 to permit the trunk selecting operation of the selector Q2 on the normal level already described. When an idle trunk line is encountered by the switch Wipers 225 to 227 inclusive, which it will be assumed is the trunk line terminating in the bank contacts 235 to 237 inclusive there will be no ground potential present upon the bank contact 235 and no circuit will be completed for the interrupter relay 205. A circuit is thereupon effective which extends from ground by way of front contact and amature 218, switching relay 200, back contact and armature 221, rotary oi normal springs RS, and relay 205 to battery. The switching relay 200 is energized over this circuit in series with the interrupter relay 205. The latter is not operated to aiect its armatures by reason of the high resistance of the switching relay. The relay 200 upon operating opens a point in the circuit of the release magnet 208 at armature 213, opens a point in the test circuit at armature 210, and its back contact, and at the front contact of this amature prepares a holding circuit for the relay 200, and at

armatures

211 and 212 disconnects the trunk conductors and 181 from the windings of the line relay 201 and extends them by way of the

switch wipers

226 and 227, bank contacts 236 and 237,

trunk conductors

305 and 306 to the windings of the battery supply relay 240. The battery supply relay 240 at operators position O is energized over a circuit including the trunk conductors and operates to 4complete a circuit at armature 242 for the slow acting relay 241. The slow acting relay 241 upon energizing establishes a holding circuit for the switching relay 200 of the selector Q2 at armature 243 and at amature 244, completes a circuit for the supervisory lamp L2.

In the selector Q2 the operation oi.' the relay 200 brings about the deenergization of the line relay 201 and the consequent opening of the circuit of the slow acting relay 203. The slow acting relay 203 is energized to open a point in the circuit of the switching relay 200 after a short interval of time. The switching relay 200 is now maintained energized by ground supplied by ths armature 243 of the relay 241.

The lighting of the supervisory signal L2 apprises the operator that a call is waiting and she will throw the key K1 associated with the tnmk line seized and communicate with the calling party to ascertain his wishes. She may then establish the remaining connection in any usual or well known manner.

When the subscriber at sub-station M replaces his receiver upon the switch hook, the relay 240 in the operator's trunk circuit is deenergized to open the circuit of the slow acting relay 241. After a short interval of timethe relay 241 is deenergized to open the circuit oi the switching relay 200. The switching relay 200 in the selector Q3 is deenergized to complete a circuit for the release magnet 208 at the rotary oi! normal springs RS. 'Ihe release magnet 208 operates to restore the switch wipers 225 to 227 inclusive to normal, whereupon its circuit is opened at the oil normal springs RS. The equipment at the distant exchange is thus restored to normal. This release operation of the equipment at the distant exchange occurs as a result of the deenergization of the line relay 151 in the repeater R2 by the opening of the bridge across the

trunk conductors

180 and 181 at armature 164. The deenergization of the line relay 151 also opens the circuit of the slow acting relay 152. The slow acting relay 152 is deenergized to remove ground from the release trunk conductor 179, thereby opening the holding circuit of the switching relay 100 in the line switch LS in addition to opening the locking circuit of the slow to energize relay 156. The slow to energize relay 156 is deenergized to remove the short circuit from the relay 155 at armature 158 and to open its locking circuit at armature 177. The deenergization of the switching relay 100 in the line switch LS restores the circuits of the line switch to normal.

The equipment employed in the call is released in the above manner.

It is now considered that the subscriber at substation A who has an automatic telephone desires to make a call to another subscriber whose number is such that his line is accessible over the trunk lines extending from repeaters such as R2. In order to accomplish this result the subscriber at sub-station A will remove his receiver from the switch hook and dial the digits of the call subscribers number, the first digit being 2 in the present instance.

Responsive to the removal of the receiver at the calling telephone A, the line switch LSl which may be of the same type as the line switch LS is operated in a manner similar to that already described to select a trunk line extending to an idle rst selector which it will be assumed is the tlrst selector P2. As a result of the extension of the calling line by the line switch LS1, line relay 116 of the iirst selector P2 is energized to establish a circuit for the slow acting relay 117. The slow acting relay 117 is operated to prepare a circuit for the vertical magnet at armature 129, and to establish a holding circuit for the line switch LS1 at armature 128. 'I'hese operations occur responsive to the removal of the receiver at the calling station A.

When the calling device at sub-station A is operated in accordance with the first digit 2 of the call subscribers number two interruptions will be produced in the circuit of the line relay 116 and this relay will retract its armature 127 twice. At each retraction oi' the armature 127 there is a circuit completed which extends from ground by way of said armature and its back contact, back contact and amature 126, armature 129 and its front contact, slow acting relay 118 and vertical magnet 120 to battery. operated to raise the switch wipers 137 to 139 inclusive two steps opposite the second level of bank contacts. The slow acting relay 118 is en` ergized in series with the vertical magnet 120 and operates to complete a circuit which extends from ground by way of front contact and armature 128, amature 132 and its front contact off normal spring 131 and its working contact and interrupter relay 119 to battery. The interrupter relay is energized at the irst o ff normal step of the switch to prepare a circuit for the rotary magnet 121 at'armature 135 and to establish a locking circuit for itself at armature 134. A short interval after the cessation of the operation of the line relay 116 the slow acting relay v118 is deenergized to complete a circuit for the rotary magnet at armature 132 and its back contact. The rotary magnet 121 is energized to advance the switch wipers 137 to 139 inclusive into engagement with the first set of bank contacts on the second level. The rotary magnet also brings about the opening of the locking circuit of the relay 119 at armature 133. Relay 119 is deenergized to open the circuit of the rotary magnet 121 which is also deenergized. If the bank contacts engaged by the switch wipers 137 to 139 inclusive are associated with a busy trunk line, there will be a ground potential present upon the test contact engaged by the switch wiper 137 and there will be a circuit completed extending from said ground armature 123 and its back contact, back contact and armature 133, off normal spring 131 and its working contact and interrupter relay 119 to battery. The interrupter relay 119 will be energized over this circuit to establish a locking circuit for itself at armature 134 and to complete a circuit at armature 135 for the rotary magnet 121. The rotary magnet 121 is energized to advance the switch wipers into engagement with the next set of bank contacts and to open the circuit of the interrupter relay 119. The interrupter relay 119 and the rotary magnet 121 continue to operate alternately until the switch wipers 137 to 139 inclusive are brought into en.- gagement with the bank contacts associated with an idle trunk line which it will be assumed arethe bank contacts 141 to 143 inclusive. In this instance there will be no ground potential present upon the bank contact 141 and no circuit will be completed for the interrupter relay 119. A circuit is now effective for the switching relay 115 which extends from ground by way of front contact and armature 128, relay'115, back contact and armature 133, oif normal spring 131 and its working contact, and relay 119 to battery. The switching relay 115 is the 'only one operatively .energized over the abovecircuit because of its high resistance. The relay 115 upon operating opens a` point in the circuit of a release magnet The vertical magnet is gized over a circuit including the calling line and operates to complete a circuit for the slow acting relay 152 at armature 163 and to complete a bridge across the trunk conductors and 181 at armature 164 and the slow acting relay 152 is energized to prepare a circuit for the slow acting relay 153 at armature 168 to complete another point in the bridge circuit across the

trunk conductors

180 and 181 at armature 166, and to complete the circuit for the polarizing winding of the electropolarized relay 154 at armature 167. A furtherresult of the operation of the relay 152 is that at armature 167 there is a holding circuit established for the switching relay 115 of the selector P2 and the holding relay of the line switch LS1. This holding circuit is established prior to the deenergization of the slow acting relay 117 of the selector P2 which occurs a short interval of time after the deenergization of the line relay 116 following the operation of the switching relay 115.

The bridge across the

trunk conductors

180 and 181 establishes a circuit for the line relay 201 of the incoming selector Q3 over a path that may be traced from ground, lower winding of differential relay 202, lower winding of line relay 201, back contact and armature 212, conductor 181, front contact and armature 164, right-hand winding of impedance relay 158, normally closed springs controlled by armature 162, winding of polarized relay 154, normally close'd springs controlled by armature 169, front contact and armature 166, trunk conductor 180, armature 211 and its back contact, upper winding of line relay 201 and upper winding of differential relay 202 to battery. The diierential relay 202 is not operated over the above circuit since the current flow in its upper and lower windings oppose. However, the line relay 201 is energized to complete a circuit for slow acting relay 203. The slow acting relay 203 is energized to open a point in the circuit of the releasing magnet at armature 219 'slow acting relay 153 is energized to change the bridge across the

trunk conductors

180 and 181, excluding the windings of the relays 158 and 154, the bridge extending from conductor 181 front contact and armature 164, armature 169 and its front contact, front contact and armature 166 to trunk-conductor 180. At each retraction of the armature 164 this bridge circuit which includes the line relay 201 of the incoming selector Q3 is interrupted. The relay 201 is thus deenergized twice to retract its armature 214. At each retraction of the armature 214 of the selector Q3 there is a circuit completed which extends from ground by way of armature 214 and its back contact, back contact and armature 213, armature 219 and its front contact, relay 204 and vertical magnet 206 to battery. The vertical magnet 206 is operated to raise the switch wipers 225 to 227 inclusive opposite the second level of bank contactsk exclusive of the normal level. The slow acting relay 204 is energized in series with the vertical magnet 206 and upon the nrst oif normal step of the switch completes the circuit which extends from ground by way of front contact and armature 218, armature 220 and its iront contact, working contact of of! normal spring 217 and said spring, and interrupter relay 205 to battery. The interrupter relay 205 is energized to establish a locking circuit for itself at armature 222 and to prepare a circuit for rotary magnet 207 at armature 223. A short interval of time after the cessation of impulses to the vertical magnet the slow acting relay 204 is deenergized to complete a circuit for the rotary magnet at armature 220 and its back contact. The rotary magnet 207 is energized to advance the switch wipers 225 to 227 inclusive into engagement with the first set of bank contacts on the second level. 'I'he operation of the rotary magnet also brings about the opening of the locking circuit of the interrupter relay 205 at armature 221 and this relay is deenergized to open the circuit of the rotary magnet which is also deenergized. l

In the repeater R2 a short interval of time after the restoration of the calling device at calling sub-station A to normal, the slow acting relay 153 is deenergized to restore the bridge across the

trunk conductors

180 and 181 in the repeater R3 to include the windings of the relays 154 and 158.

In the selector Q3 if the rst set of bank contacts on the second level are associated with a busy trunk line there will be a ground potential present upon the bank contact engaged by the test wiper 225 and a circuit will be completed for interrupter relay 205. The interrupter relay is energized to establish a locking circuit for itself and to complete a circuit for the rotary magnet 207. The alternate operation of the interrupter relay 205 and rotary magnet 207 continues until the switch wipers 225 to 227 inclusive are brought into engagement with the bank contacts associated with an idle trunk line which it will be assumed are the bank contacts 230 to 232 inclusive.

In this instance there will be no ground potential upon the test contact 230 and the rotary operation of the selector Q3 will cease. The circuit ls thereupon effective for the switching relay 200 in series with the interrupter relay 205. The operation of the switching relay 200 extends the calling) line by way of the

wipers

226 and 227

trunk conductors

301 and 302, armatures 261 and 262 to the upper and lower windings of the line relay 248 of a third selector P3. The line relay 248 is operated over a circuit including the bridge across the

trunk conductors

180 and 181 at repeater R3. The line relay 248 upon operating completes a circuit for the slow acting relay 247 at armature 259. The slow acting relay 247 is energized to prepare the circuit of the vertical magnet 252 at armature 258,.and to place ground upon the release trunk at armature 257, thereby establishing a holding circuit for the switching relay 200 of the selector Q3. lished prior to the deenergization of the slow acting relay 203 which follows a short interval of time after the deenergization of the line relay 201 This holding circuit is estab lcircuit ofthe line relay 151 of the repeater R2.

By the operation of the line relay 151 a corresponding number of interruptions will be produced in the circuit of the line relay 248 of the third selector P3. The deenergizations of the line relay v248 bring Aabout the operation of the vertical magnet 252 to raise the switch wipers 270 to 272 inclusive opposite the proper level of bank contacts. Relay 246 is energized in series with the vertical magnet and operates to complete a circuit for the interrupter relay 245. The interrupter relay is energized to establish a locking circuit for itself and to prepare a circuit for the rotary magnet 251. A short interval of time after the cessation of interruptions in the circuit of the line relay 248 the slow acting relay 246 is deenergized to complete the circuit ofthe rotary magnet. The rotary magnet is operated to advance the switch wipers into engagement with the bank contacts associated with the rst trunk line on the level selected. The trunk selecting operations occur in the same manner as before described in connection with the selector Q3. When an idle trunk line is selected the switching relay 249 is energized to extend the calling line to the connector switch.

The connector is operated in accordance with the last two digits in the called number to select the call line in any usual or well known manner. When the called party answers, the direction of current flow over the trunk circuit including the electropolarized relay 154 is reversed to bring about the energization of this relay in the repeater. 'I'he operation of the relay 154 brings about the completion of the talking circuit at armature 172 and the energization of the relay 150 at armature 173. The relay 150 is operated to reverse the connections of the line relay 151 with respect to the calling line for metering or other purposes.

When the conversation is terminated the replacement of the receiver at Vthe calling substation A brings about the deenergization of the line relay 151. As a result of this operation the bridge across the

trunk conductors

180 and 181 is opened at armature 164 and the relay 152 is deenergized after a shorter interval of time. The deenergization of relay 152 removes ground from the release trunk conductor thereby opening the holding circuit of the switching relay 115 cf the ilrst selector P2 as well as the circuit of the switching relay of the line switch LS1. The selector P2 and line switch LSl are restored to normal responsive to this operation. The release of the switches Q3 and P3 follows as a result of the deenergization of the line relay in the connector switch in any usual and well known manner. From the foregoing it will be seen that the trunk

line comprising conductors

180 and 181 is capable of special uses, this trunk line being one of a number which may be employed for calling various operators in a manner similar to that already described. It will be seen that the trunk line is really divided into two portions at the incoming end. When seized over one of the branches the selector Q3 is caused to operate to select an idle trunk on its normal level and extend the ,calling line to an operators position. When seized over the other branch the incoming selector functions in the usual manner. i

It maybe desirable to have the operator at position O function as a toll recording operator and in this instance it is desirable that the automatic subscribershave access to trunk lines extending to this position. 'I'his is illustrated in Fig. 2 by assigning the tenth or old level of the first selectors for such calls. It will be seen that when the calling subscriber at substation A desires to call the operator at O that the operation of the calling device at station A for this digit will bring about the operation of the selector- P2 to select an idle trunkon the tenth level. It y will be assumed that this trunk line terminates in the bank contacts 144 to 146.inclusive, and that this is selected by the selector P2.` As a result ofthis operation the

relays

155 and 156 function to bring about the energization of the\ differential relay 202 in the incoming selector Q2. As a result of this voperation the selector Q3 is caused to rotate on its normal level and select an idle trunk line leading to the operators position at O.

As mentioned before, it may be desirable to have a number of operators positions accessible over the trunk lines leading to selectors such as Q3.

This result can be accomplished by providing a selector such as P2s interposed between the operators positions and the normal level of the selectors such as Q2. This arrangement is shown in Fig. 4. In this instance in order to select an operators position another digit must be dialed by the calling subscriber to operate the -selector such as P23 to select the desired group of operators. The selector P22 in lthis instance is an'ordinary third selector. Selectors such as P23 are also ordinary selectors and function in anobvious manner.

From the foregoing the. functioning of his invention including the divided trunk and other special instances as brieflydescribed in connection with the trunking diagram of Fig. 1 will be obvious. In special instances it will be seen that a trunk line of this character may be employed to trunk tandem througha plurality of exchanges where such a result is necessary for the ideal or economical distribution of trailic.

It is to be pointed out that the incoming selectors such as Q3 are brought into operation lat the same time that the repeater R2 is seized lso that no time is lost in the extension of the call to the operators position.

It will be seen that his invention obviates the use of special trunks for certain purposes such asA the calling of operators. The plan may be used in effecting calls to very special operators or telephones enabling a large general traflic trunk group to handle special traiiic. General traiic may be handled by any and all trunks while trafiic to various operators may be-routed over certain of these general traflic trunks which are asline having two branches, an automatic-switch,

telephone lines, means for directively controlling said switchover one branch of said trunk line to establish a connection with one of said lines. and

means automatically operative when said `trunk line is seized over the other branch for establishing a connection with another of said lines.

2. In an automatic telephone system, a trunk line having two branches, an automatic switch, telephone lines and operators position, means for directively controlling said switch over one branch of said trunk line to extend a connection in the direction of one of said telephone lines, and means automatically operative as 'a result of seizing the trunk line over the other branch for extending said connection to said operators position.

3. In an antomatic telephone system, a trunk line extending from a first exchangeV to a second exchange and terminating at the second exchange in an incoming selector, a pair of branches for said trunk line at said first exchange, means op- \erative over said trunk line when seized through one of said branches for directively-controlling said selector, and means operative over said trunk line when seized over the other of said branches vfor automatically operating said selector.

4. In a telephone system, a trunk line extending from the lrst exchange -to the Vsecond exchange, a repeater associated with said trunk line in the iirst exchange, a selector switch associated with said trunk line in said second exchange, said trunk line having a plurality of branches at the rst exchange, means operative over said trunk line when seized over one of said branches for l:directively controlling said selector, and means operative as a result of seizing said trunk line over another of said branches for automatically operating said selector.

5. In a telephone system, a trunk line extending from the first exchange to the second exchange, a repeater associated with said trunk line in the rst exchange, a selector switch associated with said trunk line in said second-exchange, said trunk line having a plurality of branches at the rst exchangameans operative over said trunk line when seized over one of said branches for directively controlling said selector, and means associated with said repeater automatically operative whensaid trunk line is seized over another of said branches for bringing about the automatic operation of said selector. y

6. In a telephone system, a trunk line terminating in an automatic switch, vsaid trunk line having a' plurality of branches, means operative when said trunk line is seized over one of said branches for directively controlling said switch, and means operative when .the trunk line is seized over another of said branches for initiating an automatic operation of said switch. 4

7. In a telephone system, a trunk. line terminating in an automatic switch, said trunk line having two branches, means associated with one of said branches for operating said switch, means operative over the other of said branches for directively controlling said switch, and means voperative as a result of seizing said trunk line over the first mentioned branch for initiating the operation of Vsaid operating means.

8. In a telephone system, telephone lines directively controlled automatic switches for establishing talking connectionsbetween said lines, `each connection employing a predetermined Vnumber of directively controlled switches and 9. In a telephone system, telephone lines, auton matic switches directively controlled from any calling one oi' said lines for establishing a conncction with a called one of said lines through a predetermined number of said switches serially related, and means for establishing a talking connection between said calling and called lines through a greater number of said switches serially related and directively controlled from said calling line.

10. In a telephone system, a trunk line terminating in an automatic switch, said trunk line having three branches, means operative when said trunk line is seized over one of said branches for directively controlling said switch, and means operative as a result of seizing said trunk line over either of the other branches for automatically operating said switch.

11. In a telephone system, manual and automatic lines, a trunk line and operators position directively controlled automatic switches for establishing a connection between a calling and a called automatic telephone line over said trunk line` and means automatically operative when a manual telephone line is extended to said trunk line for extending said connection to said operators position.

12. In a telephone system, manual and automatic telephone lines, a line switch associated with each telephone line, a trunk line, an operators position, automatic switches, means for directively controlling certain of said automatic switches from a calling one of said automatic telephone lines to establish a connection with a called one of said telephone lines over said trunk line, means operative over one of lsaid manual telephone lines for seizing said trunk line, and means operative as a result of such seizure for extending said connection to said operators position.

13. In a telephone system, manual and automatic telephone lines, a line switch associated with each telephone line, a trunk line, an operators position, automatic switches, means for directively controlling certain of said automatic switches from a calling one of said automatic telephone`lines to establish a connection with a called one of said telephone lines over said trunk line, means operative over one of said manual telephone lines for seizing said trunk line, and means operative as a result of such seizure for extending said connection to said operators position, and means for operating certain of said automatic switches from an automatic telephone line to extend a connection to said operators position.

14. In a telephone system, manual and automatic telephone lines, a line switch associated with each telephone line, a trunk line, an operators position, automatic switches, means for directively controlling certain of said automatic switches from a calling one of said automatic telephone lines to establish a connection with a called one of saidtelephone lines over said trunk line, means operative over one of said manual telephone lines for seizing said trunk line, means operative as a result of such seizure for extending said connection to said operators position, and means for operating certain of said automatic switches from an automatic telephone line to extend a connection to said operators position over said trunk line.

15. In a telephone system, a rst and a second exchange trunk line extending between said exchanges, telephone lines at each exchange, automatic switches in each exchange, means for establishing a connection between the telephone line in one exchange by certain of said automatic switches in each exchange over said trunk line, an operators position at the second exchange, and means including said automatic switches and one of said trunk lines for extending a telephone line at the first exchange to said operators position.

16. In a telephone system, a trunk line terminating in a selector, said switch having ten levels of bank contacts and a normal level of bank contacts, means for directively operating said switch over said trunk line to select any one of said ten levels, and means automatically operative over said trunk line to initiate the rotation o! said switch on its normal level.

17. In a telephone system, a rst exchange and a second exchange, telephone lines in each exchange, trunk lines connecting said exchanges, automatic switches in each exchange, a plurality of operators positions at said second exchange, means including certain of said automatic switches at each exchange and one of said trunk lines for establishing a connection between a telephone line in each exchange, and means for establishing a connection from a calling line in the iirst exchange to one operators position over certain of said trunk lines and to another operators position over certain other of said trunk lines.

18. In a telephone system, a iirst and second exchange, trunk lines connecting said exchanges, telephone lines in each exchange, automatic switches in each exchange, means including certain of said automatic switches in each exchange and any one of said trunk lines for establishing connections between the lines in the ilrst exchange and second exchange, a plurality of operators positions, means for associating each operators position with a group of said trunk lines, and means operative from a calling line in the rst exchange to establish a connection with any one of said operators positions solely over one of the associated trunk lines.

19. In an automatic telephone system, a main exchange and a sub exchange, telephone lines in said sub exchange, rst selectors in said main exchange, trunk lines connecting said sub and main exchanges, means controlled over one oi.' said trunk lines from a telephone line in the sub exchange for directively controlling one of said ilrst selectors, a second main exchange, and means controlled from said second main exchange over one of said trunk lines for initiating the automatic operation of one of said first selectors.

20. In a telephone system, manual and automatic lines, a trunk line terminating in an automatic switch, an operators position, directively controlled automatic switches for establishing a connection between a calling and called automatic telephone line over Asaid trunk line including said automatic switch and means operative when a manual telephone line is extended to said trunk line for automatically operating said switch to extend the connection to said operators position.

21. In a telephone system, an automatic switch, a plurality of groups of trunk lines accessible to said switch, another group of trunk lines acces-v sible to said switch means for directively controlling said switch to select any group of said trunk lines of said plurality and means for initiating the automatic operation of said switch to select a trunk line in said other group.

22. In a telephone system, a first exchange, an intermediate exchange, a third exchange, a selector in the iirst exchange, trunk lines leading from a level of said selector to the third exchange, a trunk line at the end of said level leading to the intermediate exchange, selector and connector switches in the third exchange, means responsive to the operation of the iirst said selector for seizing an idle trunk in said level leading directly to the third exchange to extend the calling line to a selector in said third exchange, means for operating the connector and selector in the third ei'. 1nge to extend the calling line to a called line in the third exchange, means whereby ii all *he trunks in said level are busy the iirst said selector will select a trunk at the end of said level leading to the intermediate exchange, a selector switch at the end of said trunk in the intermediate exchange automatically operated responsive to seizure of the trunk to extend the trunk to a said selector in the third exchange, and means whereby said selector and the connecto-r in the third exchange may be operated to extend the calling line in the iirst exchange to a called line in the third exchange.

23. In a telephone system, a first exchange, an intermediate exchange, a third exchange, a selector in the first exchange, trunks from a single level of said selector leading directly to the intermediate and third exchanges respectively, selector and ,onnector switches in the thirdexchange, and means whereby if all of the trunks leading directly to the third exchange are busy the call will be extended over' a said trunk to the intermediate exchange and automatically to a selector in the third exchange, whereby a call from a calling line in the rst exchange may be extended to a called line in the third exchange by direct or indirect trunking responsive to the same number of digits sent from the calling line.

24. In a telephone system, a iirst exchange, an intermediate exchange, a third exchange, a selector in the rst exchange, trunks from a single level of said selector leading directly to the intermediate and third exchanges respectively, selector and connector switches in the third exchange, and means whereby if all of the trunks leading directly to the third exchange are busy the call will be extended over a said trunk to the intermediate exchange and automatically to a selector in the third exchange, whereby a call from.

a calling line in the first exchange may be extended to a called line in the third exchange by direct or indirect trunking responsive to the same number of digits sent from the calling line, said indirect trunking connection having more switches than the direct trunking connection but including an automatically operated switch to extend the connection from the first exchange over a 'said trunk through the intermediate exchange to the third exchange.

25. In a telephone system, a trunk line extending from the rst exchange to the second exchange, a lrepeater associated with said trunk line in the first exchange, a selector switch associated with said trunk line in said second exchange, said trunk line having a plurality of branches at the first exchange, means operative over said trunk line when seized over one of said branches for bridging the trunk branch conductors for directively controlling said selector, and means operative as a result of seizing said trunk line over another of said branches for grounding one of the trunk branch conductors for automatically operating said selector.

26. In a telephone system, a trunk line extending from the first exchange to the second exchange, a repeater associated with said trunk line in the iirst exchange, a selector switch associated with said trunk line in said second exchange, said trunk line having a plurality of branches at the first exchange, means operative over said trunk line when seized over one of said branches for bridging the trunk branch conductors for directively controlling said selector, and means operative as a result of seizing said trunk line over another of said branches for grounding one of the trunk branch conductors for automatically operating said selector, one of the two latter said means including bridging the trunk conductors of one branch and the other means including the grounding of one `of the trunk conductors of the other branch.

27. In a telephone system, a trunk line extending from a iirst exchange to a second exchange, a selector switch terminating said trunk line in said second exchange, two branches for said trunk line at the rst exchange, selector switches for connecting with said branches, means lor bridging the branch conductors oi one branch when selected by a selector for causing the selector in the distant exchange to operate as a directive selector switch, and means for grounding one of the conductors of the other branch when selected by a selector switch to cause the selector in the second switch to automatically operate as a rotary switch over a normal level thereof.

MILTON S. FRIENDLY, CENTRAL REPUBLIC BANK AND 'I'RUST COMPANY, Coezecutors of the Estate of Herbert M.

Friendly, Deceased, GREENBAUM,

By CHARLES J.

- Assistant Trust Oicer.