US2228392A

US2228392A - Telephone system

Info

Publication number: US2228392A
Application number: US128051A
Authority: US
Inventors: Kiner Glenn
Original assignee: Kellogg Switchboard and Supply Co
Current assignee: Kellogg Switchboard and Supply Co
Priority date: 1937-02-27
Filing date: 1937-02-27
Publication date: 1941-01-14
Anticipated expiration: 1958-01-14

Description

Jan. 14,1941. GKINE 2,228,392

TELEPHONE SYSTEM Filed Feb. 27, 1937 6 Shets-Sheet 1 In Lieu-1113f EZEz-zn Kine? Jan. 14, 1941. G. KlNER TELEPHONE SYSTEM 6 sheets sheet 2 Filed Feb. 27, 1937 v III-In:

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Jan. 14, 1941. e. KINER TELEPHONE SYSTEM 6 Sheets-Sheet 5 Filed Feb. 27. 1957 Jan. 14, 1941. G. KINER 2,228,392

' TELEPHONE SYSTEM Fild 'Feb. 27, 1937 6 Sheets- Sheet 4 Jan. 14, 1941. G'KlNER 2,228,392

TELEPHONE SYSTEM Filed Feb. 27, 1957 6 Sheets-Sheet 5 LIE 21f".- LIE fin KIFIE Jan. 14, 1941. K|NER 7 2,228,392

TELEPHONE SYSTEM Filed Feb. 27, 1937 6 Sheets-Sheet 6 E 2 S R &

JUL/B17151: .EIE'I'IT'I KIFIE'F ."EJg

Patented Jan. 14, 1941 UNITED STATES;

TELEPHONE SYSTEM Glenn Kiner, Park Ridge, 111., assignor to Kellogg Switchboard and Supply Company, Chicago, Ill., a corporation of Illinois Application February 27, 1937, Serial No. 128,051

6 Claims.

My invention relates to telephone systems and more particularly to telephone systems of the type in which remotely located lines terminating at a satellite exchange are interconnected at a central point by apparatus which is controlled by an operator located at a distant main exchange.

Systems of this kind are used in rural districts where the number of lines is so small that the expense of maintaining an operator at the central point to establish the connection is prohibitive.

My system contemplates the use of lines of the magneto or local battery type in which a plurality of stations may be bridged across each line and provided with code ringing.

A feature, of my invention comprises means,

located at a central point at which the various.

lines converge, controlled by an operator over a trunk line to interconnect stations on any two of said lines or any two stations on any one of said lines.

Another feature of my invention is the provision of means in ,the above described system which permits the use of repeaters between certain of the connections.

Still another feature of my invention is the provision of means whereby a line can be connected at the central point through a repeater and to another line.

Another feature of my invention permits the connection of a line terminating at the central point through a repeater to a trunk line extending to the exchange.

Another feature of my invention is the provision of means located at the central point to interconnect a pair of subscribers lines through one repeater and to interconnect two other lines through another repeater simultaneously with the existence of the first connection.

Another feature of my invention is the provision of means whereby in order to establish a connection between two of said lines, the operator dials a number which'corresponds to a combinationof the lines rather'than, as is usual, the number of the station desired.

Before going into a detailed description of the present system; perhaps it will be helpful to outline in a general way the manner in which it operates. A series of line connecting relays, such as disclosed in Fig. 5', is provided for each of the lines terminating at the local central point or station. At the local station there isalso. provided a stepby step switch which is operated under the control of a sending device at the main exchange actuated by an operator at the said main exchange. The purpose of the present construction is to provide relays located at the central point which will establish the desired connection and will then be locked up. These relays are pnergized in various combinations due to" the setting of the-step bystep switch under the control of-the operators dial. For instance if it is desired to connect a calling line at the local centralpoint to another line terminating at said central point, the operator will dial a number corresponding to the connection desired and the settingof the switch under the control of the operatorsdlal will automatically operate to energize and lock up the relays, individual to the respective lines, which are necessary to establish and maintain the connection. After the called party has been signalled, the switch may be released to be employed in establishing subsequent connections; the connection being maintained by the relays which are locked up during conversation.

In establishing a connection between two lines terminating at the local central point, one of the line connecting relays, such as shown on Fig. 5, individual to each of the lines, will be energized and locked up. While the present application discloses but four local lines, it is obvious that the number of lines may be considerably increased. The. number of line connecting relays in each line circuit, such as shownon Fig. 5, and individual to the lines respectively willv also be somewhat increased by the increase in the number of lines terminating at the local central point.

The system also provides for rvertive calls and calls from subscribers at the local exchange to those whose lines terminate at the main exchange and vice versa.

For a more complete understanding of my invention reference may be had to the drawings comprisingv Figs. 1 to 6 inclusive, Figs. 1 to 5 of which, when placed consecutively from left to right, show a schematic circuit drawing of my telephone system.

The apparatus disclosed in. Fig. 1 to the left of the dotted lines, which indicate the trunk line extending from the exchange to the central point or station, shows the equipment necessary at the exchange. The apparatus in Fig. 1 located to the right of thedotted lines and all the apparatus in Figs. 2, 3, 4, and 5, is located at the local central station or satellite.

My system in its present embodiment contemplates the useof four separate lines, each having a plurality of substations thereon. It is. so arranged that different connections can be established by the operation of individual relays, only one of such relays in each line circuit being operated on each respective connection andeach respective relay establishing a different connection.

The line circuit apparatus shown in Fig. 5 is furnished for each one of the lines terminating at the central station and certain of the conductors terminating in Fig.5 are shown as being multipled through'the relays in the other line circuits. These conductors are connected to contacts in all the other line circuits corresponding to those shown in Fig. 5. Each of these line circuits has four conductors extending tovarious contacts of the selector switch partially shown in Fig. 4. Certain of the contacts of the switch have been omitted as shown by the dotted lines, but Fig. 6 shows all the contacts of the switch and their connections. A more complete description of these connections will be given later on.

The relays of the line circuit associated with line Ll shown in Fig. 5 establish connections as follows:

The operation of line connecting relay SOR connects the calling subscriber on line Ll to the operator at the distant exchange. The operation of line connecting relay OCL connects the operator at the distant exchange to line Ll when a subscriber on line Ll desires to be connected to another subscriber on line L|. The operation of line connecting relay GCR connects the operator or any line at the exchange, to called line L| through a repeater and the operation of line connecting relays SCA and SCB establishes connections through a repeater between any two of the local lines.

It is believed a better understanding of my invention can be had by following the operation of my system in the establishment of the various connections which are as follows:

Subscriber calls operator Let us assume that the subscriber on line Ll L2 desires to call the operator to supply her with certain information. The subscriber on L! initiates the call by operating the hand generator located at the substation to give one long ring. The operator of the hand generator sends ringing current over the line conductors to operate the ringing call relay IRC. This circuit can be traced from one side of the generator at the substation, conductor L2, contacts l2, l3, l4, l5, and I6, condenser through the winding of the polarized relay IRC, normal contacts I8, I9, 20, 2|, and 22, and conductor 23, to the other side Ll of the line and hand generator. Ringing call relay IRC cioses contact 24 to establish an obvious energizing circuit for the ringing relay RR which closes its contact 25 to establish an energizing circuit for the ringing relay RA, which closes its alternate contact 26 to complete an energizing circuit for the ringing hold relay RH. This relay RH is operated by current flowing from grounded battery, through the winding of relay RH, makebefore-break contact 21, alternate contact 25 of relay RA, conductor 28, normal contact 29 of busying relay BR in Fig. 2, normal contact 38 of relay RPC, conductor 3 I normal contact 32 of genera-tor cut-oiT relay GCO to ground. Relay RH establishes a locking circuit for itself which can be traced through its make-before-

break contacts

21 and 33, conductor 34, and normal contact 35 of disconnect relay DSO, in Fig. 3, to ground.

Relays RA and RR are constructed so that they are slow to release their contacts and therefore remain energized for a short time after the ringing called relay IRC has deenergized. After the lapse of this time the relays RA and RR restore their contacts to normal and the original energizing 70 circuit for relay RH is interrupted but this relay remains energized through the previously described locking circuit. An energizing circuit for the generator relay GR in Fig. 1 is now closed. This circuit may be traced from grounded battery through the winding of relay GR, normal contact 36 of generator cut-off relay GCO, conductor 37, normal contact 33 of relay SOR, in Fig. 5, alternate contact 39 of relay RH, conductor 34, and over the previously traced locking circuit for relay RH to ground at normal contact 35 of disconnect relay DSO.

Generator relay GR operates and closes its alternate contacts 40 and 4| to connect generator current to the trunk line (shown in dotted lines) which extends from the connecting or central station to the exchange at which the supervising operator is located. The circuit for this generator current can be traced from the generator leads, Fig. 1, through alternate contact 46 of relay GR, trunk line conductor TL, normal contact 42 of dial relay DR, normal contact 43 of jack J, through the winding of the drop DP, normal contact 44 of jack J, normal contact 43| of relay DR, trunk line conductor TL, alternate contact 45 to the other generator lead. The drop DP is actuated by this flow of generator current and the signal S is displayed before the operator to indicate to her that a subscriber desires attention.

Meanwhile, the ringing relay RA has restored its contact 26 to normal to establish an energizing circuit for the subscriber-to-operator connecting relay SOR. This relay is energized by current flowing from grounded battery, normal contact 45, alternate contact 46 of relay RH, normal contact 26 of relay RA, conductor 28, normal contact 29 of busying relay ER in Fig. 2, normal contact 30 of repeater connecting relay RPC, conductor 3| in ground at normal contact 32 of relay GCO in Fig. 1.

The line connecting relay SOR establishes a locking circuit for itself through its alternate contact 41 and conductor 34 to ground at normal contact 35 of relay DSO in Fig. 3.

Relay SOR closes its alternate contact 38 to establish an energizing circuit for the generator cut-01f relay GCO in Fig. 1. The relay GCO is energized by current flowing from grounded battery through the winding of generator cut-off relay GCO, conductor 48, alternate contact 38 of relay SOR, alternate contact 39 of relay RH, conductor 34, normal contact 35 of relay DSO to ground. The generator cut-off relay GCO opens its contact 36 to interrupt the energizing circuit for the generator relay GR which restores its con tacts 40 and 4| to normal and disconnects the generator current from the trunk line. The opening of contact 32 of relay GCO removes ground from the original energizing circuit of the relay SOR in Fig. 5 but the said relay SOR is maintained energized through its locking circuit.

The operator at the central exchange noticing the displayed signal S will insert the plug P associated with the usual cord circuit into the jack J which will disconnect the drop DP from the jack connections and will also establish a talking circuit between the operator and the calling subscriber. This talking circuit can be traced from the subscribers line conductor L2, over line conductor normal contacts |2, |3, I4, and I5 of the line relays, alternate contact 6 of relay SOR, conductor 49, alternate contact 50 of relay B in Fig. 1, through the windings and 52 of the repeating coil RC, alternate contact 53 of relay DCO, conductor 54, alternate contact I3 of relay SOR in Fig. 5, normal contacts I9, 20, 2|, and 22, line conductor 23, through the substation apparatus, back to the line conductor Ll The current through windings 5| and 52 of repeating coil RC sets up an induced current in windings 55 and 56 which current travels over the heavily marked talking conductors through the jack J and plug P to the operators set. The subscriber at line L| is enabled to convey the message to the operator over the talking circuit just traced.

Disconnection of subscriber from operator- After the termination of the conversation between the operator and the subscriber, the connection can be severed and the apparatus restored to normal by either the subscriber or the operator ringing off; Let us first assume that the connection is destroyed by the subscriber operating his hand generator to sever the connection.

Current will flow from one side of the hand generator through line conductor L2, normal contacts l2, l3, l4, and I5, alternate contact l6 of relay SOR, conductor 49, through the disconnect relay DIS, conductor 54, alternate contact |8 of relay SOR, normal contacts I9, 20, 2|, and 22, and line conductor 23 to the other side of the line and hand generator.

If the operator also rings off the disconnect relay DIS will be operatod by current flowing through alternate contact 51 of ringing key RK, plug P, contact 43 of jack J, normal contact 42, over the trunk line TL, normal contact 40, windings B and 55 of repeating coil RC, normal contact 4|, trunk line TL, normal contact 43| of DR, contact 44 of jack J, alternate contact 58 of the ringing key RK, back to the source of ringing current. This current passing through windings 55 and 5'5 of repeating coil RC induces a like current in the windings 5| and 52 which current passes through the alternate contacts 50 and 53 of generator cut-ofi relay GCO to

conductors

45 and 54 and thence through the winding of the disconnect relay DIS. Current from either or both of these sources passing through the disconnect relay DIS causes the said relay to close its contact 59 to establish an obvious energizing circuit for the disconnect relay DSO which opens its contact 35 to disconnect ground from the looking circuits of relays RH and SOR, which accordingly restore to normal. The relay DSO deener- 'gizes as soon as the ringing current is removed from the line due to the opening of contact 59 of relay DIS and the apparatus is then at normal. The same result is obtained if only one party rings off.

Subscriber callsparty cm the same line The. operation of the systemin establishing a connection between two subscribers located on the same line is the same as previously described up to the point where the subscriber is connected to the operator at the exchange.

Assuming that the subscriber is connected to line L|L2 and desires to be connected to arr-.- other subscriber on the same line, the calling subscriber will inform the operator of the de-- sired connection and will then operate thehand generator as above explained to disconnect his line. The operator will dial 2 which is the calling number for line 1 in establishing such a connection. The operation of the dial D in Fig.

nate contact 42 of 'DR,.trunk line TL, normal contact 40 of generator relay GR, windings" 5B and551of repeating coil RC, normal contact 4| of relay GR, trunk line TL, alternate contact43| of. dialing relay DR and 1ead.63 to the source of high. frequency dialing. current. This current passing. through thewindings 55: and'56 of the repeatingcoil RC will .set. upfalike. current in the windings 5| and 5210f, the repeating coil RC. Thiscurrent will. flow fromwinding 5|, normal contact 50 of generator cut-01f relay (300, which relay restored its contacts. to. normalwhen the calling. subscriber rang off, conductor 64,. condenser 65, high frequency dialing. relay HFR, conductor. 66, normal contact 53 of relay GCQ. and winding 52. of repeating coil RC. passing through the winding of. the highv fre quency dialing relay HFR will cause the saidrelay'to energize. and close its contact 61 to establish an energizing circuit for the impulse relay IR which closes its. contact 68. to establish an obvious energizing circuit. for the holding impulse relay HIR. The relay HIR opens normal contact 69 to prevent the premature operation of the switch release magnet. RM.'(Fig. 4) and closes its alternate contact to establishan energizing circuit. for the dial hold-over relay DI-IO. The relay DHO is: energized by current flowing from grounded battery through the winding Qf'DI-IO, alternate contact H! of relay HTR to ground at alternate contact 68 of relay IR. The closing of contact Hi of relay HIR also establishes an energizing circuit for the motor magnet MM (Fig. l) which circuit can. be traced from grounded battery through the winding of' motor magnet MM, conductor 3M, closed contact 10 of relay HIR (Fig. 3)., closed contact 68 of LR to ground. Motor magnet M will energize and deenergize two times in accordance with the. 2dialedtby the operator.

Each time the motor magnet MM is deenergized the wipers W|, W2, and W3, Fig. 4," are moved; onev steppover thecontact banks A, B,

and C.

In the meantime, the relay DI-IO has energized and closedalternate contact H to establish obviousenergizingcircuits for the lead opening relays LOR andLOA. The. lead opening relay LOR opens its normal contacts l2',*'|3, and 14 to prevent the disturbing of any existing connections or the settin up of any false. or: undesired connections as the'wipers pass over the contacts of the contact" bank. The relay LOA establishes a locking circuit for itself through its alternate contact '15'to ground at normal contact 16 of control relay CO. It also opens its contact 11 to prevent the operation of the release magnet RM at this time. As soon as the dialing stops the relays HFR, IR, and HIR are deenergized and shortly thereafterthedialhold-over relay DHO, which is of the slow-to-release type, deenergizes andopensthe energizing circuit for the lead opening relay LOR which accordingly restores its contacts to. normal to close the switch Wiper leads.

After the dialing has ceased an energizing circuit for the line switching relay LSW in Fig. 5 is established and this relayis operated by current flowing from grounded battery throughthe windingrof the relay LSW', conductor 18, wiper W| of contact bank A, which has been stepped two contacts, conductor 19,; normal contact M of relay LOR, through the winding of control relay CO to ground. The relay vCO is also energized by current. flowing'over'this circuit and opens its contact 16 to destroy the locking circuit for relay [6 This current LOA which is accordingly deenergized and closes its normal contact 71 to establish an energizing circuit for the release magnet RM, which magnet is energized by current flowing from grounded battery through the winding of release magnet RM, conductor 302, normal contact 69 of I-IIR, normal contact 80 of relay DHO, normal contact T! of relay LOA, normal contact 8! of hold over rel'ay HOV, to ground at the off-normal contacts ON which assume their off-normal position upon the first movement of the wipers WI, W2, and W3. The release magnet RM restores the wipers Wl, W2, and W3 to their normal positions.

The relay LSW which operated over the previously described circuit closes a locking circuit for itself which may be traced through its alternate contact 82, conductor 83, normal contact 84 of the trunk release relay TRI to ground at the master ground MG. The operator called line con- 'through the winding of RFC, conductor 86 to ground at alterntae contact 85 of relay OCL.

The operator at the exchange next throws her ringing key RK to the ringing position which closes alternate contacts 51 and 58 to connect the ringing current leads to the trunk line TL to permit the passage of ringing current over the said trunk line and through the windings 55 and 56 of the repeating coil RC. Current is induced in windings 5| and 52 of the repeating coil RC and travels over normal contact 58 of relay GCO, conductor E l, alternate contact 21 of relay RPC, windings 88 and 89 of the repeating coil RCA, alternate contact 90, conductor 66, normal contact 53 of relay GCO, winding 52 of repeating coil RC. Current traversing the windings 88 and 89 of the repeating coil RCA sets up an induced current in the windings 9| and 22, which current travels through normal contact 93 of relay ARR, con-- cluctor 94, alternate contact l5 of relay OCL, normal contacts l4, l3, and I2 of the line relays, line conductor 1 I, through the call bell of all the stations on line Ll-L2, line conductor 23, normal contacts 22, El, and 23, alternate contact Ill of relay 'OCL, conductor 95, normal contact 96 of relay ARR and winding 22 of the repeating coil RCA. Ringing current is sent out over the line in the proper code to summon the desired called party and as soon as the call bells stop ringing the calling party and the called party remove their receivers from the switchhooks and the talking circuit is established between the respective stations on the same line.

Release of trunk by operator The operator next dials 1 to clear the trunk line and render it available for another connection. The dialing relays cause the operation as above described of the motor magnet MM which upon deenergization steps the wipers WI, W2, and W3 to the first set of contacts in the contact banks.

As soon as the dialing ceases the dialing relays HFR, IR, HIR, etc., restore to normal and the circuit is closed for the trunk release relay TRR in Fig. 4. This relay is energized by current flowing from grounded battery through the winding of trunk release relay TRR, the wiper Wl, conductor it, normal contact '14 of LOR, the winding of control relay CO to ground. Relay TRR opens its'normal contact 84 and removes the master ground MG from the conductor 33 which causes the deenergization of the line switching relay LSW and the relay OCL which restore their contacts to normal. Relay TRR closes a locking circuit for itself and is maintained operated by current flowing from grounded battery through the winding of relay TRR, alternate contact fil, conductor 98, and off-normal contacts ON to ground.

The control relay CO is also energized by current flowing over the previously described path and opens contact 76 to cause the relay LOA to restore its contacts to normal and close an energizing circut for release magnet RM which restores the switch wipers SWI, etc., to normal. The opening of off-normal contacts ON by the restoration to normal of the switch wipers opens the locking circuit for the relay TRR and also for the release magnet RM, both of which relays restore their contacts to normal. All the apparatus used in establishing the connection is now at normal and available for establishing another connection.

When the subscribers have finished conversing they simply restore their receivers to the switchhooks which places the line in its normal condition. There is no necessity for their ringing off as the line apparatus and trunk line have been cleared by the previous operations.

Line 1 calls line 3 In the establishment of a connection between a subscriber on line 1 and a subscriber on line 3, the subscriber on line 1 will operate his hand generator to signal the operator at the exchange in the manner previously described. After the operator is connected to line 1 the subscriber on line 1 will inform the operator that he desires to talk to a subscriber on line 3. After the subscriber has given the operator this information they will ring off as explained above in a previous connection which will disconnect the subscriber on line i from the trunk line.

The operator will consult her connection chart and discover that the dialing number to establish the desired connection is 02. The operators connection chart follows:

Dial number directory Dial NO. Line #1 calling line #1 2 Line #2 calling line #2 3 Line #3 calling line #3 4 Line #4 calling line #4 5 Through connection to line #1 with repeaten 6 Through connection to line #2 with repeater 7 Through connection to line #3 with repeaten 8 Through connection to line #4 with repeaten 9 Line #1 calling line #2 with repeater 01 Line #1 calling line #3 with repeater ()2 Line #1 calling line #4 with repeater 63 Line #2 calling line #1 with repeater 04 Line #2 calling line #3 with repeater 65 Line #2 calling line #4 with repeater 06 Line #3 calling line #1 with repeater 07 Line #3 calling line #2 with repeater Line #3 calling line #4 with repeater 09 Line #4 calling line #1 with repeater 001 Line #4 calling line #2 with repeater 002 Line #4 calling line #3 with repeater 003 Release 1 In the usual operation the operator will first dial the digit 0 which will cause the operation of the high frequency dialing relay HF'R, the impulse relay IR, the hold impulse relay HIR. the dial hold-over relay DHO, and the motor magnet MM. The lead opening relays LOR and LOA will be energized to open the wiper leads as above described. Due to the slow-to-release construction of relays I-IIR and DI-IO, these relays remain energized during the intervals between the dialing impulses. The motor magnet MM is energized and deenergized and steps the wipers WI, 'W2, and W3 into engagement with the tenth set of contacts in the contact banks. As soon as the wiper WI engages the tenth contact an energizing circuit for the holdover relay HOV and the control relay CO is established. This circuit can be traced from grounded battery through the winding of the -ho1dover relay HOV, conductor I98, contact I9, wiper Wl, conductor 19, normal contact M of relay LOR which deenergizes shortly after the last impulse of current in the dialing of the digit to ground through relay CO, Fig 2. The relay .l-IOV is energized over this circuit and opens its. alternate contact 8| to prevent the operation of the release magnet RM at this time. Relay CO energizing opens its contact "It to interrupt the lo'cking'circuit of the relay LOA.

Next the operator dials the digit 2 which will cause the switch wipers to be moved two more steps into engagement with the twelfth set of contacts. As soon as the wipers left the tenth contact the relays HOV and CO were deenergized with the result that the relay LOA and lead opening relay LOR. Relay LOR closing I its normal contacts I2 and I3 establishes energizing circuits for the subscriber connecting relay SCA in line circuit 1 and subscriber connecting relay SCB in line circuit 3. The energizing circuit for SCA in line circuit 1 can be traced from grounded battery, winding of SCA normal contact 99, conductor I99, the twelfth contact in the bank B, wiper W2, conductor IIlI, normal contact I2 of relay LOR, conductor I02 to ground at normal contact Hi3 of relay LU. Relay SCA energizes over this circuit and closesa locking circuit for itself through its alternate contact I04, conductor I05, the winding of relay LK, normal contact I96 of relay ODD, conductor "I61, normal contact I98 of relay DU to ground. The original energizing circuit for the line connecting-relay SCB in line circuit 3 will be from grounded battery, through the winding of relay SCB in line circuit 3, normally closed contact I09, conductor III! to the twelfth contact in the contact bank C, wiper W3, conductor III, normal contact I3 of relay LOR, conductor I12, normal contact II3 of relay LK to ground.

It is to be understood that while this circuit is shown and described as being the line connecting relay $03 in the line circuit shown in Fig. 5, it is not this relay that is operated but the corresponding relay in the: line circuit L3, not shown. The conductor III) shown in the drawings is connected on thecontact bank in the manner shown in Fig. 6; that is, conductor IIQ associated with line 1, the line circuit of which is shown in Fig. 5, is connected to contacts IA, IL and 2|, while the conductor no. shown associated with line 2 is connected to contacts I I, I8, and 22. The conductor H9 associated with line 3 is connected to contacts I2, I5, and- 23, while the conductor I II) associated with line 4 is connected to contacts I3, I6, and 19. The locking circuit for the relay SCBcanbe traced from .untila connection through it is desired.

grounded battery through the winding of the relay SCB in line circuit 3, alternate contact H4, conductor II 5, through the winding of locking relay LU, conductor HE, alternate contact i ll of relay LK to ground. The repeaterA is of the well known cold type which is non-operating When the contact II! is closed current flows from battery over conductor H8 to ground at IN.

.The 'fiowof current over this circuit renders the repeater active and ready to transmit the message. an energizing circuit for the relaySWR in Fig. 2 and this relay is energized by current flowing from grounded battery through the winding of relay SWR, conductor II9, alternate contact I33 of relay LK, conductor IE I, alternate contact I22 of relay LU to ground at alternate contact 123 of relay LRR which is energized when the ringing key is operated as described below. The relay SWR establishes a locking circuit for itself through its alternate contact I24, conductor I25, normal contact 84 of trunk release relay TRR. to the master ground MG. The relay SWR energizes and opens its contacts I26 and I2! to disconnect the trunk line from the repeater B so that no disturbance will be created by the application of ringing current to the trunk line.

The operator next throws the ringing key BK to connect ringing current across the trunk line conductors TL and through the windings of the repeating coil RC. This current is induced in thewindings and 52 of the repeating coil RC and passes through the windings of the ringing relay RRA which closes its contact I28 to establish an obvious energizing circuit for the conditioning relay CON, which closes its alternate contact I29, which closes an obvious energizing circuit for repeater control relay REC. The relay REC closes its contact I30 to establish an energizing circuit for the line ringing relay LRR which circuit is energized by current flowing from grounded-battery through the winding of relay LRR, alternate contact I3I of relay LU, conductor I32, alternate contact I33 of relay LK, con- The line ringing relay LRR opens normal contacts I38 and I39 to disconnect the repeater A and .to connect the ringing current which is prescut on the leads III] and I4! to the windings I42 and I43 of the repeating coil ROB. This current is induced in the opposite windings of the repeating coil RCB and travels over the heavily marked conductors I44 and I45 to the line conductors of line 3 which are not shown in the drawings. Ringing current passing over this circuit will operate the ringers at allthe stations on line 3 and it will be necessary ,for the operator to use a code ringto inform the subscribers on the line which particular subscriber is wanted. As soon as the operator restores the ringing key RK to the relays RRA, CON, and REC-restore to normal and the energizing circuit for the line ringing;

relay LRR is destroyed and the said relay LRR restores to normal to disconnect the'ringing current from the called line and to establish a talking circuit for the subscribers through the -repeater A. The subscriber hearing the bell ringhis code will remove his receiver from the switchhook and thereby. be connected across the line conductors.

In the meantime, the calling subscriber on line The operation of the relay LU establishes.

. 4 ductor I34, normal contact I35 of busying relay 5 .BR, normal contact I36 of r-elayRPC, conductor I31, alternate contact I39 of relay REC to ground.

' 1 Will wait an appreciable lengthof time and then again remove his receiver to connect his telephone across the line conductors I I and 23 and the two subscribers will be connected into a conversational circuit through the repeater A. This talking circuit can be traced from line conduct I I of line 1, normal contact I2 of line connecting relay $03 in line circuit I, alternate contact I3 of line connecting relay SCA in line circuit I, conductor I46, windings I41 and I48 of repeating coil RCC, conductor I49, alternate contact 2| of relay SCA in line circuit I, normal contact 22 of S013, line conductor 23, over the line LI. The voice current set up in the windings I4! and I48 of the repeating coil R00 are induced in the opposite windings of the repeating coil RCC and flow over conductor I55, the windings of the gain control coil, conductor l5I, through the repeater A, the gain control coil, normal contact I38 oi LRR, windings I43 and I42 of the repeating coil RCB, normal contact I3'9 of relay LRR through the coils of the gain control, conductor I52, back to the windings of the repeating coil RCC. The voice currents set up in the windings I42 and I43 of the repeating coil R03 are induced in the opposite windings of the repeating coil R013 and travel over the conductors I44 and I45 to the subscriber on line 3 in the same path as described for the ringing current for that line.

The wipers WI, W2, and W3 of the switch are only momentarily engaged with the twelfth set of contacts in the contact banks to establish the energizing circuits previously traced. The wiper WI when it engages the twelfth contact of bank A establishes an energizing circuit for the control relay G0 which relay is energized by current flowing from grounded battery through the twelfth contact of the bank A, over conductor It, through normal contact 74 and the winding of the control relay CO to ground. It will be noted in Fig. 6 that contacts II to I9 inclusive on bank A are connected to grounded battery through a. resistance coil I53. The relay CO energizing opens the locking circuit for the relay LOA which deenergizes and closes its contact IT to establish an energizing circuit for the release magnet RM. The release magnet RM energizes and returns the switch wipers WI, W2, and. W3 to their normal positions which opens the ofi-normal contacts ON to interrupt the energizing circuit for the release magnet RM.

After the operator has completed the ringing of the called line she will operate her dial D to send one impulse of current over the trunk line. This one impulse of current will cause the stepping of the wipers WI, W2, and W3 to the first contact of the bank. Wiper WI will establish a previously traced energizing circuit for the trunk release relay TRR which relay will open its contact 84 to remove the master ground MG which will interrupt the locking circuit for the relay SWR which relay SWR deenergizes and again connects the trunk line to the repeater B. The relay TRR. locks up through its alternate contact ill to ground at the off-normal contacts ON. Immediately after the dialing impulse is discontinued an energizing circuit for the release magnet RM is again established with the result that the switch wipers WI, etc., are returned to normal and the trunk line and operator are entirely disconnected from the established connection.

Disconnection by subscribers Ziter the termination of the conversation either one of the subscribers can restore the connecting apparatus to normal by ringing off. The opera tion of the hand generator on line 3 will cause the operation of the called subscribers disconnect relay CDI, the circuit for the current being traced from line 3, conductor I44, through repeating coil RCB, conductor I45 to the other side of line 3. This current is induced in the windings I42 and I43 of the repeating coil RCB and passes through the winding of the relay CDI which relay closes its alternate contact I54, to establish an energizing circuit for the relay CDR which closes its contact I 55 to close an obvious energizing circuit for the relay 0138 which closes alternate contact I56 to cause the energization of the disconnect relay DU which opens its contact IE8 to interrupt the energizing circuit for relay SCA for line circuit I and relay SCB in line circuit 3.

The same result can be obtained by the subscriber on line 1 operating his hand generator which will cause the operation of the disconnect relay CDA by current flowing from the hand generator, line conductor II, normal contact I2 of SCB in line circuit I, alternate contact I3 of relay SCA in line circuit I, conductor I45, windings I47 and I48 of repeating coil RCC, conductor MS, alternate contact 2| of relay SCA in line circuit l, normal contact 22 of SCB in line circuit I, conductor 23 to the other side of the hand generator. Current flowing over this path causes the energization of the relay CDA and the successive operation of relays CDB, CDC, and CDD. Relay CDD energizing opens contact I06 to interrupt the locking circuit for both relay SCA in line circuit I and relay SCB in line circuit 3. These relays deenergize' and restore their contacts to normal to sever the connection between the subscribers. The disconnect relays are only momentarily energized and subsequently restore thereby setting all the apparatus in its normal condition.

Through connection over trunk line Should one of the subscribers desire to converse with a subscriber located beyond the exchange he will call the operator in the usual manner previously described and will inform the operator of his code ring and line together with the code ring and line of the desired subscriber, after which both the subscriber and the operator ring oil to disconnect the trunk line.

The operator will proceed to obtain the desired connection, and assuming that the subscriber is located on line 1, the operator will dial the numeral 6 which is the calling number for line 1 in such a connection. The dialing relays will operate in the manner previouslydescribed to step the switch wipers into engagement with the sixth contact. When the wipers stop in the said sixth contact an energizing circuit for line relay LSA in line circuit I will be established. This relay will be operated by current flowing from grounded battery through the winding of relay LSA, conductor I58, sixth contact of contact bank A, wiper WI, conductor I9, normal contact I4 of relay LOR in Fig. 2, the winding of relay CO to ground. Relay CO is also energized by this flow of current and opens its contact I6 to interrupt the locking circuit for the relay LOA which closes its contact TI to complete the energizing circuit for the release magnet RM which relay energizes and restores the switch wipers WI, W2, and W3 to their normal positions. The opening of the off-normal contacts ON interrupts the energizing circuit for the release magnet RM which also restores. The relay LSA in operating closed its alternate contact I59 to establish an energizing circuit for the line relay OCR and it closes a looking circuit for itself to the master ground MG. The relay OCR closes alternate contacts I4 and 20 to connect the line LI over conductors TTL, to the repeating coil RCD. The closing of alternate contact Hit establishes an energizing circuit for the busying relay ER in Fig. 2 which relay is energized by the current flowing from grounded battery through the winding of the relay BR, conductor lei, alternate contact I60 of relay. OCR to ground. The relay BR energizes and closes alternate contact I62 to close the circuit for the repeater B and closes alternate contact I63 to cause the repeater B to be placed in service.

Next the operator will depress her ringing key RK in the proper manner to send the code ring across line 1 to summon the calling subscriber. The ringing current sent from the generator leads and through the ringingkey RK will pass over the trunk line TL, through the repeating coil RC, normal contacts 5|! and 53 of relay GCO and through the winding of relay RRA which relay operating causes the operation-of relays CON and REC. Relay REC closes alternate contact lSO to establish an energizing circuit for the repeater switching relay RES which relay is energizedby current flowing from grounded battery through the winding of relay RES, conductor I64, alternate contact I35 of relay BR, normal contact I36 of relay RPG and alternate contact I30 to ground. The repeater switching'relay RES will move contacts I65 and I56 to their alternate positions and open the leads extending to the repeater B so that ringing current will not be sent back over the trunk lineand to connect ringing current from the generator leads to the repeating coil ROD, and thence over the conductors 'I'TL and through alternate contacts I4 and 26 of relay OCR to line 1. The ringing relay RES energizes and deenergizes in accordance with the operation of the ringing key RK and transmits ringing current in the proper code over the conductors of line 1 to cause the operation ofthe call bells at all of the subscribers stations on the line.

After the operator has restored her ringing key the relays RRA, CON, REC and RES restore to normal. Contacts I65 and I66 are disconnected from the generator leads and a talking circuit is established between the subscriber on line 1 and the subscriber at the exchange over the trunk line. The voice currents set up in conductors I I and 23 of line 1 will travel through alternate contacts I4 and 2a of relay OCR, conductors TTL, and one set of windings of the repeating coil RCD. These voice currents will be induced in the other windings of the repeating coil RCD and Will flow through normal contacts I65 and I66 of ringing relay RES through repeater B, normal contacts I26 and I2! of relay SWR, normal contacts 81 and 9B of relay RPC, conductors 6d and (is, normal contacts 5%! and 53 of relay GCO, through the windings 5| and 52 of repeating coil RC. Like currents will be set up in the windings 55 and 55 of repeating coil RC, thence over the trunk line TL and through the exchange to the other subscriber.

or course, the trunk line cannot be used to set up another connection during the establishment of this connection as the opening of contact 29 of the busying relay BR will prevent the operation of any of the subscribers line relays SOR and as none of these relays can operate a calling subscriber cannot reach the operator.

After the termination of the conversation which can bedetermined by the operatorlis'tening in, the operator will releasethecircuit by dialing 1. When the switch wiper WI reaches the first contact in contact bank- A 'the trunk release relay TRR energizes overa circuit previously traced and opens its contact 84 to removev the master ground MG which opens the locking circuits. of relay LSA and OCR which restore to normal. Relay OCR opens its-alternate contacts I4 and 2% to disconnect theline Lland opens its alternate contact "I69 to'interrupt the energizing circuitof the busying relay BR which relay restores its contacts I62 and I53 to deenergize the repeater B. -The release magnet RM will also operate to restore the wipers of the switch to their normal positions and the circuit will be ready to establish another connection.

Having .thus described my invention, what I claim as new and desire to secure by United States Letters Patent is:

l. A communication system including a central station, a plurality of lines terminating thereat, call numbers, each corresponding to a combination of a definite pair of said lines, a plurality of line connecting relays, certain of said relaysbeing -individual to each of said lines, respectively,-said relays being operable in different combinations to interconnect any two of said lines, an automatic switch, a bank of contacts for said switch, im=- pulse sending means, means actuated incident to the operation of said impulse sending means in accordance with the call number representing two of said lines, for steppingsaid switch to" a corresponding contact position, and circuits of' connecting relays arranged, upon actuation, to connect said two of said lines for communication, controlled at contacts of said switch at said-position.

2. A communication system including a central station, a plurality of lines terminating thereat,

call numbers, each corresponding to a combination of a definite pair of said lines, a plurality of line connecting relays, certain of said relays being individual to each of said lines, respectively, said relays being operable in various combinations to interconnect any pair of said lines, an automatic switch, a bank of contacts for said switch, energizing circuits for said line connecting relays, respectively, each of said circuits being controlled at contacts of said switch, impulse sending means, means actuated incident to the operation of said impulse sending means in accordance with the call number representing two of said lines, for stepping said switch to a corresponding contact position, and circuits of connecting relays arranged, upon energization, to connect said two of said lines for communication, controlled at contacts of said switch at said position.

3. A communication system including a central station, a plurality of lines terminating thereat, call numbers, each corresponding to a combination of a definite pair of said lines, a plurality of line connecting relays, certain of said relays being individual to each of said lines, respectively, said relays being operable in various combinations to interconnect any pair of said lines, an automatic switch, a bank of contacts for said switch, impulse sending means, means actuated incident to the operation of said impulse means in accordance with the call number representing two of said lines, for stepping said switch to a corresponding contact position, circuits of connecting relays arranged, upon actuation, to connect said two of said lines for communication, controlled at contacts of said switch at said position, means for releasing said switch and means independent of said switch for maintaining the connection between said two of said lines.

44A communication system including a central station, a plurality of lines terminating thereat, call numbers, each corresponding to a combination of a definite pair of said lines, a plurality of line connecting relays, certain of said relays being individual to each of said lines, respectively, said relays being operable in various combinations to interconnect any pair of said lines, an automatic switch, a bank of contacts for said switch, energizing circuits for said line connecting relays, re-

spectively, each of said circuits being controlled at contacts of said switch, a link circuit, impulse sending means, means actuated incident to the operation of said impulse sending means in accordance with the call number representing two of said lines, for stepping said switch to a corresponding contact position, and circuits of con-- necting relays arranged, upon energization, to connect said two of said lines and said link circuit into a communication circuit, controlled at contacts of said switch at said position.

5. A communication system including a main station and a branch central station, a trunk line joining said stations, a plurality of lines terminating at said branch station, call numbers, each corresponding to a combination of adefinite pair of said lines, a plurality of line connecting relays certain of said relays being individual to each of said lines, respectively, said relays being operable in various combinations to interconnect any pair of said lines, an automatic switch at said branch station, a bank of contacts for said switch, energizing circuits for said line connecting relays, respectively, each of said circuits being controlled at contacts of said switch, impulse sending means at said main station, means actuated over said trunk line, incident to the operation of said impulse sending means in accordance with the call number representing two of said lines, for stepping said switch to a corresponding contact position, and circuits of connecting relays arranged, upon energization, toconnect said two of said lines into a communication circuit, controlled at contacts of said switch at said position.

6. A communication system including a main station and a branch central station, a trunk line joining said stations, a plurality of lines terminating at said branch station, call numbers, each corresponding to a combination of a definite pair of said lines, a plurality of line connecting relays, certain of said relays being individual to each of said lines, respectively, said relays being operable in various combinations to interconnect any pair of said lines, an automatic switch at said branch station, a bank of contacts for said switch, energizing circuits for said line connecting relays, respectively, each of said circuits being controlled at contacts of said switch, impulse sending means at said main station, means actuated over said trunk incident to the operation of said impulse sending means in accordance with the call number representing two of said lines, for stepping said switch to a corresponding contact position, circuits of connecting relays arranged, upon energization, to connect said two of said lines into a communication circuit, controlled at contacts of said switch at said position, means for releasing said switch and means for maintaining said established connection after release of said switch.

GLENN ICINER.