US2056730A - Printing telegraph exchange system - Google Patents

Description

Oct. 6, 1936. o. c. LEVY PRINTING TELEGRAPH EXCHANGE SYSTEM 3 Sheets-Sheet 1 Original Filed Dec. 17, 1930 UllllUlllldd -.InuEnTmr' Oct. 6, 1936. o. c. LEVY PRINTING TELEGRAPH EXCHANGE SYSTEM 2 W!- I. a L: M fi m ms 1 N E m WSW i mmi FL k I gm) WJh mm m I t In 8m Em HE A WJ w lm Fl E h mwm u r H s 4 H H 4 Rm Rm M 3mm E gm. \JI. h$m m mm LVN 4. u mMmM Em 5 m wfizw wwm wmmiml $6 \ww km U a a h. \mm a I m 7 S m m W Em Elk Assn IN b 8v m m m m Rmwwmmfhw S W wow m m m m H J 3M .9 m m6 m m Nu. \w \MSW N m Na. m wuv l Ill l'' m h N i m. www bu r 0 m www UIQILMHIP Oct. 6, 1936.-

o. c. LEVY PRiNTING TELEGRAPH EXCHANGE SYSTEM Origifial Filed Dec. 17,. 1930 s Sheets-Sheet 5 Patented Oct. 6, 1936 UNITED STATES PRINTING TELEGRAPH EXOHANG SYSTEM Oscar C. Levy, Chicago, Ill., assignor, by mesne assignments, to Associated Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Application December 1'7, 1930, Serial No. 502,899 Renewed December 14, 1932 28 Claims.

This invention relates in general to telegraph systems and more particularly to automatic switching in telegraph exchange systems wherein automatic switches are employed for establishing telegraphic communication means between a plurality of printing telegraph stations.

The principal object of the invention resides in the provision of an automatic step-by-step switching device associated with each telegraph station on a single telegraph line for establishing communication with any one of a plurality of other telegraph stations connected to the line or another line.

A further object of the invention resides in the provision of a plurality of telegraph stations connected to a single telegraph line terminating in a distant exchange point and wherein each station is provided with automatic switching devices for associating any two or more stations together over this line or with the exchange for the purpose of communicating.

Another object of the invention resides in the provision of repeating device for each telegraph line at the central exchange whereby a connection may be established from any station on a line with a station on another line, the repeating device providing means for repeating the impulses for positioning therespective switches connected to the other telegraph line.

Anadditional object of the invention resides in the means whereby the driving motors for the printing telegraph apparatus are operated only at the time when communication between another station has been established, thereby considerably reducing the Wear and tear on the printing motors at a time when noteleg'raph communications are being transmitted.

A feature of the invention resides in the means whereby special indications are automatically transmitted over the telegraph line to the stations when a particular called telegraph station is busy, when it is in condition to receive telegraphic signals, and when the automatic switches are released.

The foregoing and other objects and features not particularly pointed out will be apparent hereafter in accordance with the detailed description which together with the appended drawings constitutes a preferred embodiment of the invention.

-Referring now to the drawings, comprising three sheets; Fig. 1 illustrates a printing telegraph station together with an associated automatic switch, and a corresponding group of control relays; Fig. 2 illustrates an automatic switch General description In Figs. 1, 2, and 3 a single conductor telegraph line, indicating generally by the reference character 5 and by the heavy lines, extends from a central office A, Figs. 2 and 3, in series through a plurality of telegraph or waystations, indicated at E0, and D. This telegraph line 5 extends generally from the generator G, through the stations, such as B, for example, through the transmitting and printing mechanism TP, connector switch SC and its associated control relays CR, and to the central exchange, through the connector switch TC and its associated control relays CR, and the repeating device B, Fig. 3, to ground. This is indicated diagrammatically in Fig. 4. The other way stations C and D connected in series with the same telegraph line are equipped with the same mechanism as station B. The motor for operating the associated transmitting and printing mechanism is connected up for operation by means of the connector switch, associated with each telegraph station. At the central exchange A the connector switch TC on the same line has access over its bank contacts to a plurality of transmitting and sending mechanisms, such as TPI and TF2.

At the central exchange a plurality of connector switches, such as TC and T0 may be pro vided with the associated bank contacts connected to corresponding contacts in each switch, and a single telegraph line terminates in each connector at the central ofiice through the repeating devices R and B, so that a connection may be established from a telegraph station on any line with another station on another line. Each telegraph station on a line and the central oflice-is equipped with an impulse transmitting device which is directly connected to the telegraph line so that all of the connector switches on a particular telegraph line. may be operated by this impulse sender to position all of the switches in a manner to establish connection between any two or more stations, as will be pointed out.

At this point it may be stated that the connector switches SC and TC are of the well known Strowger step-by-step type which are operated in a primary and secondary motion by impulses transmitted from the impulse sender, such as CD, over the line, to position the switch wipers on a particular contact in accordance witha certain number assigned to any particular telegraph station. The transmitting and printing mechanism associated with the telegraph stations may be of the well known Morkrum-Kleinschmidt type in which intelligence may be transmitted by code over the telegraph line by means of an ordinary type writing transmitter and be received and decoded by the printer at the receiving end as is well known in the art.

Referring now more particularly to Fig. 4, this illustrates diagrammatically the switching schemes involved in the invention. When a subscribeiat the telegraph station, D for example, connected to the telegraph line 5 desires to establish communication with another subscriber B on the same line, he manipulates his calling device in accordance with the number associated with the telegraph station B, thereby operating all of the connector switches, but only the switch SC will position its wipers onto a particular bank contact connected with the motor of the station B. This action starts up the motor of the printing and transmitting mechanism and the telegraphic conversation can then ensue. If the telegraph station D desires to connect with two other stations on the same line, such as B and C, a difierent number is dialled by the telegraph station D so that the wipers of all the connectors at the associated telegraph stations will be positioned upon particular bank contacts, but only the motors of the printing and transmitting mechanism at both stations B and C will be operated. In this manner a single-calling telegraph station is enabled to connect with one or more stations connected to the same telegraph line. If it is desired to establish telegraphic communication with a station connected to another telegraph line the subscriber, for example, the subscriber at telegraph station B will dial a number which will operate all the switches on his line and in addition the connector switch TC at the central station A to select a repeater device such as R associated with the wanted telegraph line 5. The connector switch TC is then operated in accordance with the impulses repeated from the repeating device R which the subscriber has subsequently dialled to position the switches of the line 5 onto the desired telegraph station. If a subscriber, for example D, desires to establish communication with the central station A he will dial a particular number corresponding to the central station and operate all the switches on the line and in addition the connector TC. At the central station A it will be noted a plurality of transmitting and receiving printing mechanisms TPI and TP2 are connected to the bank contacts of the connectorTC. This is so that in case any one of the printing and transmitting mechanisms are busy at the central Staton the connector switch TC will automatically rotate its wipers over its bank contacts until an idle printing and transmitting mechanism has been found, whereupon the usual telegraphic conversation can commence.

Whenever a connection is established between any two telegraph stations it will be noted that all of the connector switches connected to the line are operated in accordance with the number of the wanted station. However, the bank contacts of the switches which are not dialled are not connected to a transmitting and printing motor, except that of the station which is called. In this manner the motors of the called transmitting and printing mechanism concerned in the connection are only operated.

From the foregoing description it will be appreciated that any number of lines may be provided, each of which have a number of telegraph stations connected in series with it and each terminating in the central office A, at which point provisions are provided whereby one line may be connected with another and the switch positioning pulses for associating the two lines together are repeated by a repeater such as R in each line. Telegraphic impulses for operating the transmitting and printing mechanisms between the various stations'on the line or lines do not have any effect whatever upon the operation of the various connector switches concerned with the establishment of the connection between the respective stations.

The telegraph line 5 indicated by the heavy line normally has current flowing over it from the generator G and at each telegraph station the line 5 extends through the transmitter key board, printer magnet, and at the telegraph station B, for example, through the windings of the line relay 55 of the connector switch SC, a number of contacts on this switch, through the impulse transmitting device CD, the line relay I0 of the control relay group CR, then to the central office A, or any other intermediate telegraph station on the line, through the line relay 300 of the connector TC and also various contacts on this switch, through the calling device CD, the line relay 2I0 of the control relay group CR, through the repeating device R, Fig. 3, and its various contacts, to the winding of line relay 435 to ground. The current flowing from the generator G over the telegraph line maintains all of the aforesaid line relays in an energized condi' tion. The various calling devices on the line, such as CD, at the telegraph station B therefor are in a position to produce a series of interruptions of the current from the generator G over the line to operate all of the line-relays at all of the stations A, B and C.

The printing magnets of the telegraph receivers along the line are not operated by the dialled impulses because the motors associated with the printing and transmitting mechanism are not running at this time, and they are only operated when the connector switch associated with a particular telegraph station is operated in accordance with the number of that station to step its Wipers upon a contact to which a relay which controls the starting of the motor is connected. In this manner the unnecessary continuous running of the motors at all the stations is prevented, and they are only operated at a time when a message is to be transmitted or received. Similarly the various line relays of the control relay groups and the connector switches at all of the telegraph stations and at the central office are not effected in any manner by telegraphic impulses. These line relays may flutter a slight amount but this will have no effect upon the operation of any of the magnets of the switches because after they have been operated they will be disconnected from control of the line relays, and the telegraphic pulses which are necessarily of a different nature than the ordinary .are momentarily deenergized.

dialled impulses will have no e'ifect upon the switches whatsoever.

It may be pointed out that the operating characteristics of the various relays shown in the embodiment of the invention are indicated only diagrammatically. The relays in which the cross hatching is indicated on the lower part of the relay indicate a relay which is slow-to-re'lease its armatures because of a copper slug on the heel end. Similarly the relays which are indicated with heavy black shading at the upper end indicate a copper slug on the. armature end so that the relay will be slow-to-operate and also slow-torelease. Certain relays such at 320, Fig. 2, have a weightedarmature 32! so that when it is attracted it closes its front contacts, but upon being released vibrates for an interval between the front and back contacts as the amplitude of the vibrations decrease until the armature comes to rest between the contacts. Other relays such as 90 and lflll have weighted front contacts so that when the relay operates the armature strikes the contact spring and starts it to vibrate. On the release of the armature the contacts again vibrate.

Detailed description I In the detailed description of the operation of the system it will be assumed now, for example, that the operator at the telegraph station B desires to establish'a connection with the central telegraph office A so that messages may be transmitted back and forth over the telegraph line 5 by means of the printing telegraph and receiving mechanism 'I'P at station B and TH at the central office A. In order to be connected with the central station A the telegraph operator at B must first operate the calling device CD in accordance with a two-digit numeral which in this case will be presumed to be No. 13. The operator will therefor operate her calling device CD in accordance with the numeral 9, thereby transmitting a single interruption over the telegraph line 5 to position all of the connectors SC on the line including those at stations C and D and the connector TC at the central office A.

Responsive to the single interruption of the line'circuit 5 the line relay 55 of the connector SC and all other line relays at all other stations Line relay 55 upon becoming deenergized restores its armature 56 and completes a circuit extending from ground at armature 56 and its back contact, armature 55 of relay 60 and its front contact, normally closed off-normal springs 58, through the winding of slow-to-release relay 65 and through the winding of the vertical magnet lit to battery. Relays (ill and 65 remain energized throughout the impulse or series of impulses if there are more due to the copper slug on their heel ends. The vertical magnet M upon operating elevates'the shaft carrying the wiper I08 of the connector SC opposite its first level of bank contacts. All of the connector switches at all of the other stations C and D are operated after the off-normal springs 58 have been operated so that further impulses of the first digit will be received over armature Gl. Relay Ml, upon operating, closes its front contact on its armature l2 and prepares a locking circuit for itself, while at armature l3 ground is extended through the front contact to complete the locking circuit for relay 85 over armature 82 and its back contact, armature 8i and its front contact to relay 85. At front contact and armature 86, relay 85 prepares the circuit for relay 80. The circuit for relay I5 is closed at front contact and armature ll of relay 'lil and relay l5 operates its armature 176 which vibrates back and forth between the two contacts until the amplitude of the vibrationshas ceased whereupon the locking circuit for relay ll) is completed by way of its armature '02. The off-normal springs upon operating, at contact 5'! open a point in the circuit for relay 90 and at contacts 59 prepare a circuit for the release magnet l2ll.

As soon as the telegraph line 5 is again closed due to the closing of the impulse springs of the calling device CD after the first digit, line relay 55 energizes and at the back contact of armature 56 opens the circuit of relay 65 which at its armature 66 and its front contact opens the initial energizing circuit of relay l0 and at its armature 58 the initial energizing circuit of relay 85. At the back contact of armature Bl the impulsing circuit is transferred to the rotary magnet M5 while at the front contact the vertical mag-' net Mil is disconnected.

The operator at the telegraph station B now operates the calling device CD in accordance with the second digit of the called number which is the digit 3, thereby transmitting a series of three impulses over the telegraph line 5 so that relay 55 will be correspondingly energized and deenergized. At each interruption of its circuit relay 55, upon deenergizing, closes a circuit from ground on armature 5B and its back contact, armature 53 and its front contact, normally open off-normal springs 58, armature 5'17 and its back contact, armature 8t and the front contact of relay 85, through the winding of the slow-release relay 80 and the winding of the rotary magnet i l5 to battery.- Relay 80 operates in this circult and at its front contact and armature 8i closes a shunt around the initial circuit for its winding over armature 86 and its front contact to prevent interference with the rotary impulses because at armature 82 and its back contact it opens the locking circuit of relay 85 which thereupon restores. The rotary magnet ll5 operates in accordance with the impulses received from the line relay 55 and rotates the wiper lllB upon.

the third set of bank contacts in the first level. This bank contact, it will be noted, is dead and is not connected to any relay for starting the motor of a printer of the associated station such as relay i H which extends from a different bank contact of the switch over conductor I09.

After the last of the series of impulses constituting the second digit of the called number,

'relay 80 restores and at its back contact and armature B2 prepares a circuit for relay I05. Relay l05 has the other side of its winding connected to the wiper I08 which is now resting upon a dead contact. For this reason the circuit for re lay I05 is not completed. The switch SC of the telegraph station B remains in its operated condition as described, with relays 55, 60, I0, 15 and the off-normal contacts all operated or energized.

Similarly the connector switches, such as SC, at

' series of impulses.

- does not energize.

the remaining stations C and D and any others on the line will have their switches operated so that thewipers rest upon a contact corresponding to the contact upon which wipe I08 is positioned. These bank contacts will likewise be dead and not connected to any relay such as relay I I I, and the connection over the telegraph line 5 remains in this condition until further operations take place which will subsequently be pointed out.

Referring now to the operation of the control relay group CR, associated with the connector SC 0f the telegraph station B, it will be noted that the line relay l0 and slow-release relay l5 are normally held energized, and, therefore, responsive to the first digit of the called number which in this case comprises a single digit, relay I 0 restores its armature II and completes a circuit from ground on armature H and its back contact, through the winding of slow-to-energize relay 20 to battery. Relay l 5 being sloW-to-release remains energized during this impulse or if the digit comprises more than one impulse during the Relay 20, upon operating, at its front contact and armature 22 connects ground to the lamp L to battery. The lighting of the lamp L indicates that the telegraph line is being used and it will be. understood that the associated control relays at the remaining telegraph stations C and D and CR- of the central office A, which are all in series of the line 5, will have their corresponding lamps L lighted at this time to indicate that the telegraph line is in use. At the front contact of armature 2| relay 20 prepares a circuit for relay 25 but relay l5 maintains its armature I 6 attracted at this time so relay 25 During the interval between the dialling of the first and second digits, relay l0 again energizes and opens the circuit for relay 20 which at armature 22 extinguishes the lamp L. However, when the second digit is dialled relay l 0 again deenergizes and closes the circuit for relay 20 to again close the circuit for the lamp L at its armature 22. When the transmission of the impulse series-comprising the second digit is terminated, relay I I again energizes and opens the circuit for relay 20 to extinguish the lamp L at its armature 22. However the lamp is almost immediately lighted again when the cut-through signal is received as will be pointed out.

The operation of the connector switch TC at the central ofiice A will now be described, it being understood that the operation of this switch takes place simultaneously with the operation of the other switches, such as SC, at other telegraph stations B, C and D on the sametelegraph line 5. The line relay 300 which responds to the first digit of the dialled number, which in this case comprises a single impulse, restores its armature 30l and completes a circuit from ground on this armature and its back contact, armature 308 and the front contact of relay 305, which remains energized during this impulse and any succeeding impulses, normally closed off-normal springs 3l3, winding of slow-to-release relay 3|0 and through the winding of vertical stepping magnet 302 to battery. Relay 3|0 upon energizing closes its front contact and armature 3l2 to complete a locking circuit for itself and at front contact and armature 3H completes a circuit for relay 3| 5. Relay 3| 5, upon energizing, prepares a locking circuit for itself at armature 3 I 1 and at front contact and armature 3l6 connects the ground from front contact and armature 301 by way of this armature through the winding of relay 320 to ture 32!.

battery. Relay 320, upon energizing, attracts its armature 32I which vibrates for an interval between its contacts and after the amplitude of the vibrations has ceased closes a circuit from ground on armature 32l by way of armature 3l1 to maintain relay 3l5 locked in energized condition after relay 3|0 restores. Relay 3|0 at its front contact and armature 306 connects ground by way of the normally closed alternate contacts of armature 331, through the Windingof relay 335 to battery. Relay 335, upon operating, completes a locking circuit for itself by way of front contact and armature 331, back contact and armature 321, and through front contact and armature 3 l8 to ground. At front contact and armature 336 it prepares the circuit for relay 325.

The vertical magnet 302, upon energizing, elevates the shaft carrying the wipers 380, 38I, 382 and 383 of the connector switch TC one vertical step opposite the first level of bank contacts. As a result of the elevation of the shaft the off-normal springs 309, 3l3 and 3M operate. As only one impulse has been transmitted, in accordance with the first digit of the called number, relay 3|0 subsequently deenergizes and at back contact and armature 3l2 prepares the rotary stepping circuit after the line relay 300 has again energized. The off-normal springs upon operating at contacts 309 maintain the circuit for relay 340 open, and at contact springs 3 l4 prepares a circuit for the release magnet 303 which is maintained open at the back contact of armature 3|8.

The remaining series of three impulses comprising the second digit are now received over the telegraph line 5 from the calling device CD at the station B and the line relay 300 is correspondingly deenergized and energized. At each deenergization itconnects ground from its armature 30l and its back contact by way of armature 308 and its front contact, normally open off-normal contacts 3l3, armature 3l2 and its back contact, front contact and armature 336, back contact and armature 354, through the winding of slowrelease relay 325, and then through the winding of the rotary stepping magnet 304 to battery. Relay 325 energizes in this circuit and at its front contact andarmature 326 completes a locking circuit for itselfv independent of armatures 336 and 354. When relay 3|0 deenergized after the first series of impulses it opened the initial energizing circuit for relay 335 at armature 306 but this relay remains locked up from ground on armature 3l8, likewise, at armature 3 the initial operating circuit for relay 3|5 is opened but it remains locked in energized condition from arma- Relay 325 at the back contact .of armature 321 also opens the locking circuit for relay 335 and this relay restores and at its armature 336 opens a part of the initial energizing circuit for relay 325. At the front contact of armature 321 relay 325 closes a circuit through the winding of slow-to-release relay 365 to battery. This relay upon energizing attracts its armature 369 to 'its front contact to prepare a locking circuit for itself. The rotary magnet 304, energized in series with relay 325, responds to the series of three impulses and rotates the wipers 380 to 383, inclusive, upon the third set of bank contacts in the first level which are connected to the transmitter and printing mechanism TPI.

After the last series of impulses, relay 325 restores and opens the front contact of armature 326 so that any additional impulses will not have any effect upon the rotary magnet 304 and move the wipers off of. the bank contacts upon which cuit for relay 310 from ground on armature 3l8,

but relay 3|5 is at this time operated.

It will be understood that the bank contacts of the connector switch TC are multipled to all other similar connector switches, such as TC, which terminate in the central office A. In this case, should the bank contacts, upon which the wipers of the switch are now resting, be in a busy condition, in other words should the transmitter and printing mechanism TP-I be in use by another connector TC onanother line, there will be ground potential on the bank contact with which wiper 383 is in engagement.

Busy condition If the line is busy and if it is not one of a group of similar lines which are connected to the same level of bank contacts, ground on wiper 383 extends over armature 368'and its front contact, relay 365 being operated at this time, back contact and armature 316, through the winding of relay 356 to battery. Relay 350 upon operating at its armature 354 opens a part of the initial energizing circuit of relay 325 and at front contact of armature 353 prepares a locking circuit for itself. At front contact and armature 35I it prepares a circuit for relay 360 which is at this time open at armature 366 and its back contact. After a short interval relay 365 deenergizes, due to the deenergization of relay 325; and at its armature 366 and its back contact closes a circult for slow-to-energize relay 360 by way of armatures 35! and 30L At front contact of armature 368 the initial operating circuit for relay 356 is opened but at the alternate contacts of this armature the locking circuit for relay 350 is closed by way of armature 316 and its back contact, front contact and armature 353, to ground 'on the front contact and armature 318 of relay 315. Slow-to-energize relay 360, upon operating closes ground from its front contact and armature 362', through the winding of this relay, and through the resistance to battery, and

connected. directly in series with the telegraph line which extends through the connector TC by way of armature 313 and its back contact, back contact and armature 34!, and armature 3H and its back contact. This opening of the line circuit for a comparatively short interval of time deenergizes the line relay 300 and all similar line relays along the telegraph line at the other way station. Relay 350upon falling away, opens its front contact from its armature 30I to disconnect ground from the Winding of relay 365 to open its energizing circuit. Relay 3613 upon deenergizing, removes the shunt circuit from its winding and again closes armature 36! upon its back contact so that relay 360 is again energized and the circuit for relay 360 will again be closed. Relay 360 upon again energizing, short circuits its winding and opens the circuit over the telegraph line 5 at armature 361 to again open the circuit of line relay 300. This alternate energization and deenergization of the line relay 300 and 360 continues intermittently, and it will be understood that the relay 305, which is normally maintained energized by relay 300 remains in this condition due to the fact that it has a copper slug on its heel end.

Busy signal The operator at the calling station B will be aware of the fact that the individual transmitting and printing equipment TPl, which has been called by him is in a busy condition, by the fact that the lamp L at his station will alternately flash off and on. This operation of the lamp L takes place when the line is first opened, by relay l ll restoring and at its back contact and armature ll connecting ground through the Winding of the slow-to-operate relay 20. Relay 20,

upon energizing at armature 22 lights the lamp L and at its front contact and armature 2| prepares a circuit for slow-to-energize relay 25 by way of armature 31 and its back contact. At the front contact of armature II, relay Ill opens the circuit for slow-to-release relay l5. Relay I5 after slowly restoring, closes the circuit for relay 25 from ground on its back contact and arma- -ture I6, armature 21 and its front contact, back contact and armature 31, normally closed alternate contacts of armature 26, through the winding of slow-to-energize relay 25 and resistance to battery. During this interval the telegraph line 5 has been again closed and line relay l0 thereby energizes, and at its armature H and front contact again completes a circuit for relay I5 which upon operating at armature l6 and its back contact opens the initial energizing circuit for relay 25, which being slow-to-operate, does not have sufficient time to completely energize of relays I0, 15, and 20 continues as long as the telegraph line is momentarily opened and again closedby armature 36I of the connector switch TC at the central office A, and each time relay 20 energizes it closes the circuit for the lamp L to indicate the busy condition of the transmitting and printing mechanism desired on the line.

Selection of idle mechanism of a group contacts over which wipers 382 and 383 rotate will therefore be strapped together as indicated, except for the last ones of the group. Should the first bank contact, upon which the wipers of the switch TC are resting, be busy, ground from the bank contact upon which wiper 383 is resting, extends over' this wiper, armature 368 and its operated front contact, back contact and armature 316, through the winding of relay 350 to battery. Relay 350, upon operating, at back contact and armature 353 opens a point in the circuit for relay 318. At front contact and armature 352 a circuit is completed for relay 338 extending from ground upon the bank contact upon which wiper 382 is resting, front contact and armature 361, armature 352 and its front contact, back contact and armature 328, armature 319 and its back contact, through the winding of relay 338 to battery. Relay 338 energizes in this circuit and at armature 333 closes ground on its front contact to complete the locking circuit for relay 365 to maintain this relay energized while the stepping magnet 384 is rotating the wipers across the busy contacts.

At the front contact of armature 332, relay 338 completes a circuit for the rotary stepping magnet 384 by the Way of front contact and armature 318 to ground and at armature 331 completes a locking circuit for itself to ground on armature 318. The rotary magnet 384, upon operating rotates the wipers 388 to 383, inclusive, onto the next set of bank contacts, and at armature 319 and its back contact opens the circuit for relay 338. Relay 338, upon restoring, at armature 332 opens the circuit for the rotary magnet 384. The rotary magnet upon restoring, closes its armature 319 upon its back contact and again completes the circuit for relay 330 over the previously traced circuit to wiper 382. If the bank contact upon which this wiper is now resting is likewise busy, ground will be connected to this wiper and relay 338 again energizes and this in turn energizes the rotary magnet 384 to step the wipers onto the next set of bank contacts. This alternate energization and deenergization of the rotary magnet 384 and the control relay 338 continues as long as grounded bank contacts are encountered by the wipers 382 and 383.

Should all of the transmitting and printing mechanisms of the group be busy, wipers 382 and 383 will be rotated to the last bank contacts of the group which are not connected together. Ground consequently will no longer be encountered by wiper 382, and relay 338 cannot again energize. Relay 338 upon falling away opens its armature 333 from its front contact and permanently opens the locking circuit for relay 365 which, it will be understood, remains energized as long as relay 338 alternately energizes and deenergizes to step the wipers across the bank contacts. At the alternate contacts of armature 368 relay 365 closes the locking circuit for relay 358 which extends from ground on front contact and armature 318, armature 353, and its front contact, contacts of armature 368, back contact and armature 316 to relay 358. At its armature 366 and back contact relay 365 also closes the circuit for slow-to-energize relay 368 by way of armature 351 and ground on armature 381. This relay upon energizing completes a locking circuit for itself from front contact and armature 362, through the resistance to battery and at front contact and armature 363 it short circuits itself so that it slowly restores. At each energization it opens and upon deenergizing closes the circuit extending over the telegraph line 5 at armature 361 and its back contact. This as has been previously explained flashes the lamps, such as L, at the telegraph station B to indicate that all of the transmitting and printing mechanisms at the central office A are busy and none are available for use.

Idle condition of mechanismleading to an idle printing and transmitting mechanism such as TPI, the locking circuit for relay 365 is opened at armature 333 and'its front contact, by relay 338. Relay 365 upon deenergizing, closes the circuit for switching relay 318 over a circuit extending from ground on armature 31B and its front contact, armature 353 and its back contact, through the upper winding of relay 318, back contact and armature 368, out over wiper 383 and the bank contact upon which it is now resting, over conductor 4 I 9, through the winding of relay 422 to battery. Relay 318 upon energizing, completes a locking circuit for itself over its lower winding independent of its upper winding through its front contact and armature 311, armature 351 and its back contact, back contact and armature 321, to front contact and. ground on armature 318. Relay 318 at its front contact and armature 315 connects ground from armature 318 direct to the wiper 383 in order to maintain the set of bank contacts busy to other switches, such as the connector switch TC, and at the front contacts of armatures 312 and 313 connects the wipers 388 and 381 in series with the telegraph line 5 by way of conductors 411 and 418.

When wiper 383 encounters the bank contact to which the conductor 419 is connected, relay 422 energizes and closes its front contact onto its armatures 423 and 424 and connects the transmitting and printing mechanism 'I'Pl directly in series with the telegraph line 5. At the front contact of armature 421 relay 422 completes a circuit for the motor start relay 428 which upon energizing, closes ground from its front contact onto its armature 429 to complete the circuit to the motor preparatory to initiating the operation of the printing mechanism. A branch of the circuit from armature 429 completes the circuit for the lamp L3 which indicates to an operator at the central telegraph ofiice A that the printing mechanism TPI has been selected over the telegraph line 5 and is about to receive a message from a station on the telegraph line.

Cut-through signal At the time relay 318 operated it also opened its front contact and armature 311 so that the telegraph line 5 is opened for the purpose of giving a cut-through signal to the operator at the telegraph station B, as will now be pointed out. At the front contact of armature 314, relay 310 likewise completes the circuit for relay 345 over a circuit extending from ground on the normally closed front contact and armature 381, through the winding of relay 345 to battery. Relay 345 upon operating, starts its armature 346 to vibrate onto its front contact so it momentarily opens and closes the circuit for relay 355 which is slowto-energize. As the amplitude of the vibrations decrease the circuit for relay 355 is closed for a longer period until finally relay 355 operates and at its armature 356 and its front contact again completes the continuity of the telegraph line 5, which has been previously opened at front contact and armature 31 I. The opening of the telegraph line 5 at armature 311 and the closing of it at armature 356 again is not of a sufiicient length of time to cause the release of the switches engaged in the connection, but is of sufficient length to permit the transmission of a cut-through signal to indicate to the operator at station B that the apparatus at the central office A is in condition to receive any messages to be transmitted.

Referring now again to Fig. 1 and the control rela'ylgroup CR, the cut-through signal transmitted over the telegraph line 5 from the connector ,switch TC restores relay l and relay 55, and relay 55 in turn opens the circuit of relay 60 but this relay does not effect the further operation of the switch because the off-normal springs 51 are now open. Armature 13 prevents release by holding open its back contact. Relay l0 upon falling away, at its front contact and armature l l opens the circuit for slow-to-release relay l and at the back contact of armature l l completes the circuit for slow-to-energize relay 20. Relay 20 upon operating, closes its front contact on armature 22 to light the lamp L and at the front contact of armature 2i prepares a circuit for relay 25. Relay l5 upon completely restoring, closes ground from its back contact onto its armature M3 to complete the circuit for relay-25 by way of front contact and armature 2 l, back contact and armature 017, normally closed alternate contacts of armature 26, through the winding and the resistance of relay 25 to battery. Relay 25 opfront contact of armature 20 and locks itself energized by way of this armature and the back contact, and armature 38 to ground. At the front contact of armature 28 it maintains the circuit for the lamp L lighted. At the front contact or armature 2'l it closes the circuit for slow-tooperate relay 30. .However, before relay 30 can become fully operated the telegraph line 5 is closed and relay l0 again becomes energized and at its front contact and armature ll completes the circuit for relay 45, which at its back contact and armature It opens the circuit of relay 30 before it can fully energize. At the back contact of armature M the circuit for relay 20 is opened and it restores its armatures again. A similar action takes place in control relay'group CRll at the central oifice A and the control relay group associated with. the other telegraph stations B and D on the telegraph line 5. If the lamp L did not become operated steadily immediately after the operator had dialled it would be an indication that the desired connection had not been completed. The lamp remains lighted as long as the connection exists.

When the operator at the telegraph station B notes that the connection which he has set up has been extended to a transmitting and printing mechanism 'IPi at the central office he will operate his motor start key ST in the mechanism TP. This closes 'the circuit to the motor of the mechanism, and a branch of it illuminates the lamp L2 to indicate that the motor of, the mecha-.

' nism T? is running. The operator may now manipulate the transmitter TP in the well known manner to transmit telegraphic impulses over the telegraph line 5 to the printer of the receiving mechanism TPl in the central station A. The printing mechanism I'Pll receives the message transmitted from the operator at the substation B and if desired, the operator at the central station A may manipulate his transmitting mechanism to reply to the message.

It will be appreciated that the telegraphic impulses corresponding to a particular message being transmitted back and forth over the telegraph line 5, extends through the remaining telegraph stations C and D and others which'may be on the line, but the mechanism at these stations remains at rest.

Release action After the telegraphic messages have been transmitted and received between the central ofiice A and the telegraph substation B and the operator at the station E desires to release the connection he momentarily presses the release key RL. This closes an obvious circuit through the winding of relay 45 to battery. Relay 45 operates its armature 46 on both of its front contacts and closes a circuit through the winding of slow-torelease relay 50 to battery. When the release key BL is released, relay 05 restores and upon restoring releases its armature 06, which due to the weight attached to it vibrates back and forth between'its contacts until the amplitude of the vibrations gradually decrease. At the front contact of armature 5i, relay 50 completes a locking circuit for itself from armature 00. As the vibrations of armature 06 decrease further the circuit for relay 50 is opened after a time interval whereupon it restores. During the interval relay 50 was operated it opened its armature 52 from its back contact, which in turn opened the circuit extending over the telegraph line- 5 for a period of time for purpose of releasing all the connector switches on this line.

In the connector switch TC at the central ofice the line relay 300 releases in response to the opening of the telegraph line 5. At its front contact andarmature 30H it opens the circuit for slow-release relay 305. After a short interval relay 305 restores and opens its front contact from its armature 30?, thereby opening the energizing circuit for relay 320 by way of armature 3B6 and its front contact, and alsorelay 305 by way of front contact and armature 310. Relay 305 upon fallingaway, opens its armature 305 from its front contact and interrupts the circuit for slow-to-energize relay 355. Relay .320 upon restoring, releases its armature 32l and vibrates this armature, due to the weight attached to the end of it, between its front and back con-' tact and as the vibrations gradually decrease the locking circuit for relay 3 i5 is opened and it interrupts its own circuit at the front contact of armature 3H, and at the front contact of armature 3H5 it opens a further point in the circuit of relay 3Z0. Relay 3l5 upon finally restoring, at its armature 3H and its front contact opens the locking circuit for the switching relay 3'50 which extended over armature 32?, 357, and 3H and their associated contacts. Relay 310 at armatures 3'52 and 313 disconnects the telegraph line 5 from in series'with wipers 380 and 38B.

At the back contact of armature 3l8 relay 3l5 completes the circuit for the release magnet 303 by wayof the off-normal springs 3M. Release magnet 303 upon operating restores the switch wipers 380, 30E, 382, and 383 to their normal position and the shaft carrying the wipers upon reaching its normal position restores the offnormal contacts 300, M3, and M0. The off-normal springs 3M upon opening interrupt the circuit for the release magnet 303. The off-normal springs 309 upon closing, complete a circuit from ground on armature 3M and its back contact, armature 308 and its back contact, off-normal springs 309, through the Winding of relay 340 to battery. Relay 300 upon operating, opens its armature 3 from its back contact thereby interrupting the circuit of the telegraph line for a period of time which is in addition to the opening of the line at armature 52 and the back contact of the control relay group CR thereby increasing the time during which the line circuit is open in order to insure the release of the switches. At the front contact of armature 342 relay 340 starts this armature to vibrate and after an interval completes a circuit from ground by way of this armature through the winding of slow-topull-up relay 355 to battery. After an interval relay 355 operates which occurs when the vibrations of armature 342 almost cease, and at the front contact of armature 356 again closes the telegraph line circuit around the open armature and contact 341. This opening of the telegraph line is similar to the opening of the line when the cut-through signal was transmitted, except that the length of time of the interval is considerably longer. The weighted armatures of relays 348 and 345 are so adjusted relative to each other in order to compensate for this time interval.

As soon as the wipers of the connector switch TC are restored to normal the circuit for relay 422, Fig. 3, is open and it restores its armatures 423, 424, and 421 to disconnect the transmitting and printing mechanism TPI from the telegraph line 5. At armature 421 relay 428 has its circuit opened so that at armature 429 the circuit for the lamp L3 is opened and the operation of the motor is stopped. The transmitting and printing mechanism TPI is now in its normal position and is ready to be again taken into use for transmitting and receiving telegraph messages. The operator at the telegraph station B restores the key ST to disconnect the lamp L2 and also stop the motor of the printing mechanism TP.

Release signal Referring to Fig. 1 relay [8 releases its armature H and opens the circuit for relay [5. At the back contact of armature II the circuit for relay 28 is closed and after an interval this relay energizes and prepares a circuit for relay 25 at its armature 2|. Relay 25, however is locked energized over its armature 26 to ground on armature 38 at this time. After relay I5 is completely restored it closes a circuit from ground on its back contact and armature I 6, armature 2| and its front contact, front contact and armature 21, through the winding of slow-to-pull-up relay 38 to battery. Relay- 38 upon operating, closes its front contact onto its armature 3i and completes the circuit for relay 35 from ground on armature I6. Relay 35 upon operating, closes a locking circuit for itself from the ground on armature l6, over armature-36 and its front contact. At the back contact of armature 38 it opens the locking circuit for relay 25 and at armature 3'! the original circuit for this relay. Relay 25 after an interval, restores its armatures and at armature 28 extinguishes the lamp L, to notify the operators at all the stations that the telegraph line is free for use. During the above operations, the telegraph line circuit is closed again and relay l8 again becomes energized and at its armature I I completes the circuit for relay l5 and at the back contact of armature II it opens the circuit of relay 28. Relay l5 upon completely energizing opens its back contact from its armature l6 to open the locking circuit for relay 35 Relay 38 opens its front contact from its armature 3| to open the circuit for relay 35. Relay 35 upon completely restoring closes its back contact onto armature 31 to again prepare the circuit for relay 25, and at its front contact and armature 36 opens its locking circuit. It will be understood that the above series of operations take place at all control relay groups, such as CR, at each of the stations A, B, and D.

The complete connection has now been released to normal and the apparatus connected to the telegraph line 5 is ready to receive another call.

Referring to the equipment in the central office A, indicated in Figs. 2 and 3 it is seen that the connector switch TC upon being operated in accordance with a particular number so that the telegraph line 5 is taken into use for the transmission of telegraphic signals, engages a particular printing and transmitting mechanism, such as TPI, and at the same time renders the bank contacts busy to other switches so that it cannot be seized from another connector, such as TCI, which is associated with another telegraph line 5'. For the same reason the repeater R, Fig. 3, must be rendered unselectable from the bank contacts of the connector switch TC. This is brought about upon the connector TC being taken into use by ground being extended from armature 3l8 and its front contact, over conductor 489 to Fig. 3', back contact and armature 44| of the repeating device R, through the winding of relay 465 to battery. Relay 465 therefore energizes and remains in this condition as long as the connector switch TC is in operated position. Relay 465 upon operating, closes ground from its front contact and its armature 466, which thereby grounds the bank contacts of the connector switch TC to prevent this switch from seizing the repeating device R.

As has beenpointed out the repeating device R is connected in series with the telegraph line 5 and is therefore associated with the connector switch TC at the central office A, the station D, and all other stations such as C and B which are connected to this telegraph line. It will therefore be apparent that when impulses are transmitted over the telegraph line 5 to position the various switches the repeater being connected in this circuit will be operated. However, at this time its operation will not have any effect as will now be pointed out.

Referring now more particularly to the repeating device R, the telegraph line 5 extends through armature 446 and its front contact, through the winding of relay 435 to ground, which is the end of the telegraph line. Current from the generator G flowing over the telegraph line 5 maintains relay 435 normally energized as well as all the other line'relays on the line. At its front contact and armature 436 relay 435' completes the circuit to relay 448 and holds this relay normally energized. Relay 448 at its front contact and armature 44l maintains relay 458 normally energized from the normally closed contacts of armatures 462 and 463 which are connected to ground and through the resistance to battery. Relay 445 is maintained energized by relay 458 from ground on the front contact of armature 45l and relay 445 therefor being energized maintains the circuit for relay 435 normally closed. This is the normal condition of the apparatus when no selecting operations are being performed over the telegraph line 5.

When an impulse or series of impulses are being transmitted over the telegraph line 5 to position various switches the circuit for relay 435 is momentarily opened and closed, depending on the number of pulses transmitted. At each deenergization of relay 435 it opens the circuit for relay 448 at armature 4%. Relay 448 upon 'deenergizing, opens its armature 44| from its front contact and closes battery to its front contact from the alternate back contact instead. The battery from the alternate back contact of armature 44l extends through the repeating relay 458 to ground on the normally closed contacts of armature 463. It is, therefore, seen that the transmission of impulses over the telegraph line 5 does not have any further effect upon the operation of the repeating device R, the impulses being merely absorbed by contacts 44E without affecting the impulsing relay 450-.

Connection with another line Let it be assumed now, for example, that the operator at the telegraph station B is desirous of establishing a connection from his telegraph line 5 with another station which may be situated on a different telegraph line such as 5. In this case, therefore, instead of operating the connector switch TC at the central omce A in accordance with a particular numeral to select one of an idle number of printing and transmitting mechanisms, such as TH and TF2, he will operate the switch TC in accordance with a special number so that it connects with the repeater R which is normally connected to the telegraph line 5. It therefore follows that an additional two-digit number must be dialled by the operator at the station E in order to operate the desired connector switch such as SC on the telegraph line 5 and to establish the telegraphic connection. When a connection ofthis type is established the telegraph line 5 is not connected directly in series with the telegraph line 5 but the repeater R is interposed between the two lines and merely repeats the impulses from the telegraph line 5 into the telegraph line 5. A description of the method of setting up this type of connection will now be men. g The operator at the telegraph station B operates the calling device CD in accordance with a particular number designating the telegraph line 5. The two series of impulses operate the connector switch SC at the station 13 in accordance with the number dialled and as has been described before, the connector elevates its wiper I08 in a vertical and a rotary motion to set the wipers upon a dead bank contact or a contact which is not connected to the printing and transmitting mechanism TP of the station B. The same two series of impulses operate the control relay group CR at the station B and also CR at the central oifice A, so that the relays such as l0, I5, 20 and 25 and the corresponding relays at all the other stations connected to the telegraph line 5 are operated and illuminate similar lamps, such as lamp L, to indicate that the telegraph line 5 is taken into use. It is assumed that the calling number transmitted by the telegraph operator B is -No. 34, consequently the two series of impulses comprising the digits 3 and 5 will operate the connector switch TC at the central office in a manner to elevate the wipers 380 to 383, inclusive, three steps and then four horizontal steps so that they will come into engagement with the bank contacts to which conductors 402, 003, and 405 are connected; If the telegraph line 5 with which the repeater R is associated should be in a busy condition the busy relay 350 of the connector TC would be operated and thereby control the transmitting of the busy flash impulses over the telegraph line to alternately energize and deenergize the relays of the control relay group CR and CR resulting in the flashing on and off of the lamp L. This occurs at each of the telegraph stations. The detailed explanation of the manner in which this takes place has been previously described and it is, therefore, not necessary to further point out this operation.

Should the telegraph line 5', however, be free at the time the connector switch T of the central office A comes into engagement with the repeater R the cut-through signal will be given as soon as the switching relay 310 of the connector TC operates and at its armature 314 and front contact, closes the circuit for relay 345 which in turn at its armature 340 completes the circuit for relay 355. Relay 310 likewise opens its back contact from its armature 31! and momentarily interrupts the telegraph line circuit over conductor which is shortly afterwards closed again as soon as relay 355 operates its armature 356 onto its front contact to shunt out armature 311 and its back contact. This momentary interruption of the telegraph line 5 transmits the cut-through signal to operate relays l0, i5, 20, and 25 of the control relay group CR to illuminate the lamp L at the station B and at all other stations. The same operation takes place in the control relay CR at the central mice A. As soon as the connector switch TC engages the bank contacts ground is extended by way of armature 318 and its front contact, armature 353 and its back contact, armature 315 and its front contact, over wiper 383, conductor 404, Fig. 3, armature and back contact 00f of relay 405, through the winding of relay 005 to battery. Relay 405 upon operating moves its armatures 401 and 405 upon their front contacts, disconnects the alternate normally closed back contacts from battery and ground and connects the line conductors 402 and 403 direct through to the repeating relay M5 by way of front contact and armature 426. The telegraph line'5 is now extended from Fig. 1, through the connector switch TO by way of armature 313 and its front contact, wiper 38!, the bank contact upon which it is now resting, conductor 403, armature 401 and its front contact, front contact and armature 426, the winding of the repeating relay 5, front contact and armature 406, conductor 402, bank contact and wiper 380 upon which it is now resting, front contact and armature 312, armature 36l and its back contact, front contact and armature 356, through the control relay group CR, including the calling device CD, relay 210 and armature 252 and its back contact, to Fig. 3, armature 446 and its front contact, and the winding of relay 435 to battery. It will thus be seen that the repeater R is now connected directly in, series with the telegraph line 5.

In order to reach the desired telegraph station on the line 5 now, it is necessary for the opera tor at the telegraph station B to dial an addition: a1 two-digit number. This additional two series of impulses, however, will have no efiect upon the operated magnets of the connector SC at the station B and the connector switch TC at the central station A, because these switches after having been operated once disconnect the stepping magnets from their operating circuits and the line relays of these switches and their associated relays will operate without effect. The second two series of impulses are repeated by the repeater R into the telegraph line 5 to position the desired switch of the called telegraph station. This takes place as follows: Immediately responsive to the first impulse transmitted .over the telegraph line 5 and thenin series over the conductors 402 and 403 of the repeater R, the repeating relay 5 deenergizes and at its armature 4I5 connects ground to back contact and armature 3. through the lower winding of twostep relay M0 to battery. Relay M0 is so adiusted that with current flowing through its lower winding it can only operate its front contact onto armature 4| I but the remaining armatures do not operate. As soon as armature 4II makes contact with its front contact the upper winding of relay M0 is connected in series with its lower winding to ground on conductor 404 by way of back contact and armature 40I. The upper winding, however, is at this time shortclrcuited by ground on armature 4I6. When the first impulse of the series goes off relay 5 again energizes and operates its armature 4I8 onto its front contact. At the back contact of this armature the short-circuit from the upper winding of two-step relay M0 is removed and the relay energizes with its upper winding in series with its lower winding and operates its armatures H2 and 4| 3 to disconnect the back contacts therefrom. At armature M3 and the back contact the original energizing circuit for relay 4| 0 is opened and at the back contact of armature 4I2 it opens the original holding circuit for relay 420 and transfers the control of this relay to the front contact of armature M6 on relay M5.

The remaining series of impulses from the calling device CD of the calling telegraph station B transmitted over the telegraph line 5 operate relay 4I5 in accordance with the impulses and at the front contact of armature 4'I6 it alternately opens and closes the circuit for relay 420 which at its front contact and armature 42I repeats the impudses into the telegraph line 5'. Relay 630 which is in the circuit over which the telegraph line 5' extends follows these impulses and at its front contact and armature 433i alternately energizes and deenergizes relay 425. Each time relay 4% deenergizes it closes its alternate normal opened contacts and connects battery through the winding of relay 430 to ground, to maintain relay 430 energized. Relay 4-30, therefore, at its armature 43i holds up relay 425 so that relay 425 will maintain its armature 426 closed onto its front contact to prevent the impulses which are being transmitted over the telegraph line 5 from being repeated back over conductors 402 and 403 into the telegraph line 5.

As soon as the connector switch TC is operated by the repeated impulses it connects ground over conductor 409' in a similar manner that the connector switch TC connected ground from armature 3I8' to conductor 409 to repeater R. In this case the conductor 409"extends over the back contact and armature 408, through the winding of relay 400 to battery. Relay 400 upon operating, closes its grounded front contact onto its armature MI and extends this ground over conductor 404, to the bank contacts upon which wiper 383 is resting in order to maintain the repeating device R busy to other connector switchesat the central ofiice A. Telegraphic communication can proceed from the transmitting and printing mechanism TP of the station B with similar equipment at the desired station on the line 5.

Connection of central ojfice with another station Assume now that a connection is desired to be established from the central office Av to the intermediate telegraph station B. The operator at the central office A manipulates the calling device CD in accordance with a number which corresponds to the number assigned to the intermediate station B. This is a two-digit number as has been pointed out and operates the connector switchTC at the central office in a manner to connect the wipers of this switch to an idle one of the printing and transmitting mechanisms such as TPI. The connector switch SC at the station B follows the impulses transmitted by the calling.device CDI and operates the line relay 55 to operate the vertical magnet IIO and the rotary magnet II5 to position the wiper I08 upon the bank contacts to which conductor I 09 is connected. The detailed manner in which this is accomplished by the switch has been pointed out heretofore and it is not thought necessary to further describe this operation. As soon as wiper I08 encounters the bank contact to which conductor I09 is connected ground from armature I3 and its front contact will extend by way of armature 82 and its back contact, through the winding of the switching relay I05, wiper I08, the bank contact upon which it is now resting, conductor I09, through the winding of the motor start relay I I I, to battery. Relay III upon energizing, closes ground from its front contact onto its armature II2 to start the operation of the motor and also illuminate the lamp L2 to indicate to the operator at the station B that the communication mechanism is in condition to be operated. Relay I05 upon being operated, completes a circuit from battery through relay I80, front contact and armature I 01, to ground on the front contact of armature t2. At the back contact of armature I06 the circuit extending over the telegraph line 5 is opened in order to transmit the cut-through signal and operate the lamp L and also LI at the central ofiice A to indicate that the connection has been cut-through. Relay Iliifi upon operating, closes its Weighted armature spring IEBII onto its front contact and as the amplitude of the vibrations decrease the circuit for slow-to-energize relay at is closed and after a short interval this relay energizes. At its front contact and armature 9t relay again closes the telegraph line 5 by way of armature Eii in shunt of the open contacts R136. The interval between the opening of armature I06 from its own contact and the closing of armature Qt onto its front contact is of sufficient duration to operate the relays I0, I5, and 20 of the control relay group CR at each of the telegraph stations including the central office A and flash the corresponding lamps. Telegraphic messages may now be communicated back and forth over the telegraph line 5 between the transmitting and printing mechanism TPI at the central omce A and the equipment TP at the intermediate telegraph station B.

Other stations connected to the telegraph line 5 will be aware that this line is in use at this time by the illumination of their associated lamps, such as lamp L of the relay group CR. Likewise the telegraph line 5 is rendered unselectable by any other connector such as TC at the central oflice A because of the fact that conductor 409 extending to the repeater R operates relay 465 which in turn closes ground onto its armature 466 to ground the bank contact of the other switches TC. Similarly ground from wipers 382 and 383 grounds the associated bank contacts upon which they are resting and which is connected to the printing mechanism TPI so that other 'switches cannot seize this equipment while it is in use, but will pass over these busy contacts and engage an idle one of the mechanisms, such as TF2, which may not be in use at this time.

When the operator at the central ofiice A wishes to terminate the conversation and release the connection he momentarily operates the release key RL. This momentarily closes a circuit for relay 255 and then opens it again. Relay 245 sets its weighted armature spring 246 to vibrate and closes a circuit from ground through both of its front contacts, through the winding of slow-to-release relay 250 to battery. Relay 250 closes its front contact on its armature 25| and completes a locking circuit for itself to the back and front contacts of armature 2%. Relay 250 remains operated for an interval and as the vibrations of armature 2% decrease in amplitude the circuit is opened after a time. During the interval that relay 25d was operated it opened its armature 252 from its back contact and opened the circuit extending over the telegraph line 5 for a comparatively long interval of time. This interval of time permits the line relay 55 of the connector switch SC at the substation B to release its armature lit and thereby open the circuit for slow-release relay M which upon releasing its armature 62 opens the circuit of relay 85 which is extended from contact 62 byway of armature ll and its front contact. Relay i5 upon restoring releases its weighted armature i6 and when the amplitude of the vibrations has ceased relay W has its locking circuit opened at front contact and armature l2. After an interval when slow-release relay ill releases it closes ground from its armatureiS to its back contact and completes the circuit for the release magnet H20 by way of the off-normal contacts 59. As a further result of the release of relay 60 a circuit is closed from ground on armature 56 and its back contact, armature 63 and its back contact, offnormal springs 51, through the winding of relay 90 to battery. Relay 90 at armature 9i opens the line 5 and at armature 92 after a time closes the circuit for relay 95 which at its armature 96 again closes the line 5. This is to insure the release of the switch SC. Relay 90 is restored when the off-normal springs 51 are opened. The'release magnet I20 upon operating, withdraws the wiper I08 from the bank contact upon which it is resting and when the shaft which supports the wiper is restored completely to normal, the oil-normal contacts 51, 58 and 59 are permanently opened.

Referring back to the connector SC, when in the releasing operation relay 6i] disconnects ground from its armature 62, it also interrupts the circuit for relay I which is extended by way of front contact and armature I01. Relay- I00 upon falling away, disengages its front contact from its weighted armature spring Illl and opens the circuit for slow-to-release relay 95 which completely restores after armature llli has come to rest. At the front contact of armature 113 the circuit for the switching relay I. is likewise opened and this relay falls back to close the circuit over the telegraph line 5 at armature I06 which has previously been closed by armature 96 of relay 95. The releasing action of the connector switch TC at the central office A is brought about in a similar manner as the connector switch SC, in that the relay 300 releases the relay 305 which upon falling away disconnects ground from its front contact and armature 301 to open the circuit for relay 320. Relay 320 after having released completely, opens the circuit for relay M5 and relay 315 at its armature 318 completes the circuit for the release magnet 303 which operates to release the wipers to normal. The release signal impulse coming over the line 5 effects the control relay group CR at each of the telegraph stations on the line as has been previously pointed out. The complete connection has been released and the switches restored, so that the telegraph line 5 is ready to receive impulses for use in establishing another connection if desired.

From the foregoing description it will be appreciated that in any call from a telegraph station along the telegraph line 5 to the central oifice A the dialled impulses will position all of the connector switches SC and the connector switch TC at the central oflice. Immediately upon the connector switch TC engaging an idle printer, such as TPl, a cut-through signal is transmitted over the telegraph line 5 to all of the telegraph stations to illuminate the lamp L steadily. This indicates to the operator at the calling station that the switch has cut-through" and is ready to receive telegraphic messages. Should the printing and transmitting device TPI be busy at the time the call is made the connector switch TC by means of relay 360 alternately opens and closes telegraph line 5 to transmit busy-flash impulses over the line and operate the lamp L in a flashing manner. When the connectors are released by operation of the key RL the relay Mil operates to open the line for another period of time so that all of the switches along the telegraph line 5 will restore to normal position and telegraphic impulses are considerably shorter and do not effect the operation of the switches.

As indicated diagrammatically in Fig. 4 and as shown in the switch SC, Fig. 1, the bank contacts of the connector switches SC may be multipled to other bank contacts of the same switch either in the same level or different levels, so that more than one connector switch such as SC may be operated to select its particular printing mechanism TP and thereby transmit telegraphic messages from one station to two or more other stations at the same time. In a case of this kind a special number would have to be dialled when selecting two or more stations than is necessary when selecting only one station. One station will thereby have two or more different numbers assigned to it. It will likewise be appreciated that this arrangement may also be provided on the telegraph line 5' so that two or more stations on this line may be selected by a single station, such as B, on the telegraph line 5. The repeating device R in each case repeats impulses from one line to the other. In this manner by strapping together several contacts on each switch numerous possible combinations of different stations are selectable in the system.

Any number of additional telegraph stations may be associated with each telegraph line from the above number indicated. Likewise, the central. office A may have any number of additional lines such as 5' extending from it and each terminating in an individual switch, such as connector switch TC. All of the bank contacts of the connector switches at the central office are ,multipled together so that one line can be autographic signals are transmitted by means of makes and breaks of the telegraph line, and while this invention has been disclosed in a system of this kind it will be understood that it may be easily converted into a duplex operating type by interspersing polarized relays at all of the local telegraph stations and across an artificial line so that negative and positive polarities of current may be transmitted over the line to operate the printing mechanisms which are then connected in local operating circuits instead of in series with the line.

While only one embodiment of the invention has been disclosed it will be understood that numerous modifications of the same may be made by those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

1. In a telegraph system, a telegraph line, a plurality of stations connected to said line, switching devices in said line at each'of said telegraph stations, an impulse transmitting device in said line at each of said stations, printing and transmitting mechanisms in said line at each of said stations, means responsive to the transmission of impulses from one of said stations on said line for operating and maintaining in an operated condition all of said switching devices, and means in each of said switching devices responsive to only a particular series of impulses from said impulse device for rendering its associated transmitting and printing mechanism operable over said telegraph line.

2. In a telegraph system, a telegraph line, a

' plurality of telegraph stations connected to said line, an automatic switch for each station connected to said line, telegraph transmitting and printing mechanism connected to each of said lines but normally inoperative, impulse transmitting mechanism at each of said stations connected to said telegraph line, means responsive to a particular series of impulses from one of said impulse transmitting devices for operating and maintaining in an operated condition all of said automatic switches on said line, and means in only one of said automatic switches responsive' to said particular impulses for rendering its associated printing and transmitting equipment operative.

3. In a telegraph system, a telegraph line, a plurality of telegraph transmitting and receiving stations connected at intervals to said line, automatic switching devices on said line at each of said stations, impulse transmitting devices in said line at each of said stations, telegraph transmitting and printing mechanism in. said line at each of said stations and normally inoperative, means responsive to the transmission of a series of im pulses from the impulse device at one of said telegraph stations for operating and maintaining in an operated condition all of said automatic switches on said line, means in only one of said connector switches corresponding to the series of impulses for rendering its associated transmitting and printing mechanism operative, and means at any of said stations for releasing all of said automatic switches.

4. In a telegraph system, a telegraph line, a plurality of stations arranged on said line, automatic switches at each of said stations, transmitting and printing mechanism at each of said stations, means at each of said stations for operating and maintaining in an operated condition the automatic switches at all of said stations and for Operating only a particular one of said transmitting and printing mechanisms associated with said telegraph line, and means controlled from any of said stations for releasing all of said automatic switches.

5. In a telegraph system, a telegraph line, a plurality of telegraph stations arranged on said line, an automatic connector switch at each of said stations connected in said line, transmitting and printing mechanism at each of said stations connected to said line and normally inoperative, means at any one of said telegraph stations for operating and maintaining in an operated condition the connectorswitches at all of said stations when calling another station, means controlled by only the connector switch of the called station for rendering its associated transmitting and printing mechanism operative, and means at all of said telegraph stations controlled by the connector switch of the called station for indicating that said telegraph line is in use.

6. In a telegraph system, a telegraph line, a plurality of telegraph stations arranged on said line, an automatic switch associated with each of said stations and connected to said line, normally inoperative telegraph transmitting and printing mechanisms at each station connected to said line, number transmitting means at each of said stations, each of said stations having a particular number assigned to it, means responsive to the operation of said number transmitting means in accordance with a particular number from one of said stations for operating and maintaining in an operated condition all of the automatic switches on said line at all of said stations, means controlled by the automatic switch of the station to which the transmitted number is assigned for rendering its associated transmitting and printing mechanism operative, means controlled by the automatic switch of the called telegraph station only for transmitting a cut-through signal over said line to the calling station, and means in said calling station responsive to said cutthrough signal for indicating that the transmitting and printing mechanism at the called station is in operative position.

7. In a telegraph system, a telegraph line, a plurality of stations arranged at intervals along said line, an automatic switch individual to each of said stations and connected to said line, normally inoperative telegraph transmitting and printing mechanisms associated with each of said stations and connected to said line, means at any of said stations for operating all of said automatic switches on said line, the automatic switch at only one of said stations being operative to render its associated telegraph transmitting and printing mechanism operative, an indicating device at each of said stations, means responsive to the operation of the switch rendering its associated telegraph transmitting and printing mechanism operative for operating the indicating device at all of said telegraph stations, and means for telegraphically communicating between the calling and the selected station over said line while maintaining said automatic switches operated.

8. In a telegraph system, a central telegraph station, a telegraph line extending from said central station, a plurality of telegraph stations ar-' ranged in said telegraph line, an automatic switch at each of said telegraph stations and at said central station, means at any of said stations for operating all of said automatic switches over said telegraph line, a plurality of telegraph printing and transmitting mechanisms at said central station, means for operating the automatic switch at said central station automatically for selecting an idle one of said printing and transmitting mechanisms, a signal at each of said stations and at said central station, and means responsive to the selection of an idle transmitting and printing mechanism at the central station for operating all of said signalling devices at all of said stations to indicate that said line is in use.

9. In a telegraph system, a central oflice, a telegraph line extending from said oflice, a plurality of telegraph stations arranged on said line, an automatic switch on said line associated with each of said stations and at said central ofiice, telegraph transmitting and receiving mechanisms individual to each of said stations, a plurality of said mechanisms at said central office, said telegraph transmitting and receiving mechanisms at said stations controlled by their associated automatic switches, means at any of said stations for operating all of said automatic switches on said line including said automatic switch at the central oflice, means in said central 5 office automatic switch for selecting an idle one of the transmitting and printing mechanisms at said central ofiice, and means at said central ofiice or at any of said stations for releasing all of said automatic switches.

10, In a telegraph system, a telegraph line, a calling and a called telegraph station on said line, an automatic switch at each of said stations controlled over said line, telegraph transmitting and 35 printing mechanism at each of said stations in said line and controlled by its associated automatic switch, a signal at each of said stations, means at the calling station for simultaneously operating both of said automatic switches for connecting their associated telegraph transmitting and printing mechanisms to said line, means responsive to the connection of said mechanisms with said line for operating the signals at said stations in one manner, means at each of said stations for releasing said automatic switches, and means responsive to the release of said automatic switches for disconnecting their associated telegraph transmitting, and printing mechanisms *"from said line and for operating the signals at 50 said stations in a different manner.

11. In a telegraph system, a central offlce, a

telegraph line extending from said oflice, a plurality of telegraph stations arranged on said line, an automatic, switch at each of said stations and at said central ofiice, telegraph printing and transmitting equipment at each of said ofiices and a plurality of said equipments at the central office, means at each of said stations in establishing a connection with said central ofiice for operating all of said automatic switches, means within said automatic switches for rendering them inoperative to further impulses, means at the central office responsive to the operation of the automatic switch thereat for selecting an idle 65 equipment thereat, indicating means at each of said stations, means responsive to the selection of an idle equipment at said central ofii'ce-for operating the indicating means at all the said stations in a certain manner, and means at any-of said 7 stations and the said central ofiice forreleasing all of said automatic switches and for operating said signals at all of said stations and at said central ofiice in a difierent manner.

12. In a telegraph system, a central oflice, a

75 telegraph line extendingfrom said ofilce, a plurality of telegraph stations arranged on said line, an automatic switch at each of said stations and at said central office, transmitting and printing mechanisms at each of said stations and a plurality of said mechanisms at said central ofiice, said mechanisms controlled by their associated automatic switches, means at any of said stations, in establishing a connection with another station, for operating its associated switch and all of said other automatic switches including that at said central oflice' to render the associated mechanisms operable, means in each of said automatic switches for preventing further operation of the switches while telegraphic communication is taking place between said stations, and means at any of said stations for releasing all of said automatic switches.

13. In a telegraph system, a central oflice, a plurality of telegraph lines extending from said oifice, a plurality of telegraph stations arranged on each of said lines, a repeater and an automatic switch in said central ofiice in which each of said lines terminate, telegraph transmitting and printing mechanisms associated with each of said stations on said line and a plurality of said mechanisms at said central ofiice, means in each of said automatic switches for rendering its associated transmitting and printing mechanism operable, means at any of said stations on one of said lines for operating all of the automatic switches on said line, and the switch associated with said line in said central office including the associated repeater, and means in said repeater responsive to the means at each of said stations for operating all of the switches on another of said lines.

14. In a telegraph system, a central ofiice, a plurality of telegraph lines radiating from said omce, a plurality of telegraph stations arranged on each of said lines, an automatic switch at each of said stations, each of said lines terminating in said central office in a similar automatic switch, a repeating device individual to each of said lines connected to the associated switch at the central oflice, selecting means at each of said stations on said lines for operating all of the automatic switches on the line and the switch at the central office and for operating the repeating device on another associated line, and means in said repeating device controlled from the selecting mechanism at one of said stations for operating all of the automatic switches on the other of said lines to which said repeating device is individual, telegraph transmitting and printing mechanism at each of said stations on said lines controlled by their associated automatic switches, means responsive to the operation of only one of said automatic switches on any of said lines in accordance with a predetermined selective transmission operation from one of said stations for causing the associated printing and transmitting mechanism to operate over the line, and means for establishing telegraphic communication between the respective stations on both of said lines.

15. In a telegraph system, a central oflice, a plurality of telegraph lines extending from said office, a plurality of telegraph stations arranged on each of said lines, an automatic switch individual to each of said stations, an automatic switch at said central station in which each of said lines terminate, a repeating device in each of said lines at said central office,-impulse transmitting means at each of said stations, means responsive to the operation of said impulse transmitting means in a definite manner for operating all of the automatic switches on the associated line and for operating the corresponding automatic switch at the central station to connect with a repeating device associated with another line, means responsive to the further operation of said impulse transmitting means at one of said stations for operating said selected repeating device to repeat said impulses into the line associated with the repeating device, and means responsive to said impulses for operating all of the automatic switches on said other line, telegraph transmitting and printing mechanism associated with each of said stations and controlled by their associated automatic switches, means responsive to the transmission of a particular series of impulses from any of said stations for operating only one of said automatic switches to render the associated transmitting and printing mechanism operative, and means on either of said lines for releasing all of said automatic switches and said repeating device.

16. In a telegraph system, a central oilice, telegraph lines extending from said oflice, a plurality of telegraph stations arranged on said lines, an automatic switch associated with each of said stations and connected to said lines, an automatic switch at said central station in which each of said lines terminate, a repeating device associated with each of said central ofiice automatic switches, means at any of said stations for operating all of said automatic switches on the line and for operating said central office switch to select a repeating device associated with another line, means at any of said stations for operating said repeater over said line to operate all of said automatic switches on said other line, means in any of said stations for releasing all of said automatic switches, and means responsive to the operation of only certain ones of said automatic switches for establishing telegraphic communication between two of said stations.

17. In a telegraph system, a central office, a plurality of telegraph lines extending from said office, a plurality of telegraph stations arranged on each of said lines, an automatic switch in each of said stations and at said central office in which each telegraph line terminates, a repeating device for each line at said central oflice, telegraph printing and transmitting equipment at each of said stations and at said central office controlled by their associated switch so as to be connected to the line, means at any of said stations on a line for operating all the switches and repeater on the line and to operate only one of the switches to render its associated printing-and transmitting equipment operable over the line, means after said equipment has been connected to the line for telegraphically communicating over the line without further operating the switches, means at one of said stations on one of the lines for operating all of the automatic switches on the line and the associated central office switch to select a repeating device of another line, means at the stations on the first line for operating the selected repeater to control all of the automatic.

switches on the other line andto control only one of the switches to render its associated transmitting and printing mechanism operable over the other line, means for telegraphically communieating between said two stations without further operating all of the automatic switches on both lines, and means at either station on either of said lines for releasing all of said automatic switches.

18. In a telegraph system, a central ofl'ice, 8-

plurality of telegraph lines extending from said office, each of said lines having a plurality of telegraph stations on them, a connector switch for each station on the line at each station and another connector switch at the central oflice in which saidlines terminate, a repeating device at the central office in which each of said lines terminate, means at any of said stations on one of said lines for operating all of its associated switches on the line and for operating its associated repeating device in a local circuit when the connection between any two stations on one line is established, means at any of said stations in establishing a connection between a station on one line and a station on another line for operating its associated repeating device in a local circuit and for operating the repeating device in another of said lines, and means in any station on said first line for extending the local circuit of said repeating device to operate all of the automatic switches on said other line to establish a connection with one of the stations.

19. In a telegraph system, a central oflice, a plurality of telegraph lines extending from said central oflice, a plurality of telegraph stations arranged on each of said lines, telegraph transmitting and printing mechanism at each of said stations on said lines and a plurality of said mechanisms at said central oflice, means at any of said stations on one line for conecting its associated printing and transmitting mechanism with similar equipment at another station on said line to establish telegraphic communication between the two stations, means at the central oifice controlled from any station for connecting any one of a number of said mechanisms at said central ofiice to the line for establishing telegraphic communication between a station on the line and the central office, means at said central oflice for establishing telegraphic connections between a station on one line to a station on another line under control of a calling station and to render the associated printing and telegraphing equipment on said other line operable over said line "to connect the calling and called stations together, and means at any one of said stations on any one of said lines over which a connection has been established for releasing all of said printing and transmitting mechanisms.

20. In a telegraph system, a central oflice, a plurality of telegraph lines extending from said ofiice, a plurality of telegraph stations on each of said lines, transmitting and printing telegraph mechanism at each of said stations and at said central office, .means at any of said stations on the line for establishing a connection with another station on said line and for automatically rendering the transmitting and printing mechanism at each station operable over the line, means at any of said stations for establishing a telegraphic connection between said station and said central office, means at said central office controlled from any of said stations on one line for completing a connection with a station on the other line and rendering the associated telegraphic mechanism operable over the lines, and means controlled from any of the stations on said lines over which a connection has been established for rendering the printing and transmitting mechanism inoperable over the said line or lines.

21. In a telegraph system, a telegraph line, a plurality of stations connected to said line, an automatic switch connected to said line at each of said stations, an'impulse transmitting device in said line at each of said stations, printing and transmitting mechanisms in said line at each of said stations, means responsive to a particular series of impulses from one of said impulse transmitting devices for operating all of said automatic switches on said line, means in all of said automatic switches for maintaining them operated between successive series of impulses, and only one of said automatic switches responsive to said particular series of impulses for rendering its associated printing and transmitting mechanism operable over said line.

22. In a telegraph system in combination, a plurality of signal transmission circuits, a plurality of stations associated with each such circuit, means at one or more stations of any circuit for transmitting pulses over its circuit, selective means at each station of each circuit responsive to pulses transmitted over its circuit whereby any station of a circuit may set up telegraphic communication with any station on its circuit or alternatively place the selective means of any other of the transmission circuits under control of said first means for one of the purposes set forth.

23. In a telegraph system in combination, a plurality of signal transmission circuits, each having a plurality of stations' associated with it and each station having a telegraph transmitting and receiving set'thereat individual to its station, another station common to said circuits and having a plurality of telegraph transmitting and receiving sets thereat, means at one or more of said stations of any of said circuits for transmitting pulses over its circuit, selective 'means at each station of each circuit responsive to pulses transmitted over its circuit whereby any station may connect its telegraph transmitting and receiving set into operative relation with the set of any other station on its circuit, and means enabling the selective means to automatically select another one of the other sets at the common station in case the selected set thereat has already been taken for use by the selective means of other of the circuits.

24. A telegraph system as specified by the preceding claim, characterized in that; there is signal means at the calling station, controlled by the selective means at the called station having a plurality of sets thereat, for so advising the attendant at the calling station if all of the transmitting and receiving sets 'ther'eat are already in use.

25. A telegraph system as specified by claim 23, characterized in that; there is signal means at the calling station, controlled by the selective means at the called station having a plurality of sets thereat, for so advising the attendant at the calling station if all of the transmitting and'receiving sets thereat are already in use, and additional means at the calling station controlled by the selective means at said called station to differently control said signal means consequent to the successful connection with a set.

26. In a telegraph system, a telegraph line, a plurality of stations connected to said line, switching devices in said line at each of said tele graph stations, an impulse transmitting device in said lineat each of said stations, printing and transmitting mechanisms in said line at each of said stationsmeans responsive to the transmission of impulses from one of said stations on said line for operating and maintaining in an operated condition all of said switching devices, means in each of said switching devices responsive to only a particular series of impulses from said impulse device for rendering its as-. sociated transmitting and printing mechanism operable over said telegraph line, and a cutthrough signal at each of the respective stations controlled by the switching device of the called station to advise the attendant at any calling station that the selected station is conditioned for telegraphic communication with the calling station.

27. In a telegraph system, a telegraph line, a plurality of telegraph transmitting and receiving stations connected at intervals to said line, automatic switching devices on said line at each of said stations, impulse transmitting devices in said line at each of said stations, a telegraph transmitting and printing mechanism in said line at each of said stations normally inoperative, means responsive to the transmission of a series of impulses from the impulse device at one of said telegraph stations for operating and maintaining in an operated condition all of said automatic switches on said line, means in only one of said connector switches corresponding to the series of impulses for rendering its associated transmitting and printing mechanism operative, means at each of said stations for opening said line for a period ordinarily sufficient to insure the proper release of all of said switches, and

means operated consequent to the full release of each switch to also open a point in the line circuit for a limited time interval to positively assure the release of all of said switches.

28. In a telegraph system, a telegraph line, a plurality of stations arranged on said line, automatic switches at each of said stations, transmitting and printing mechanism at each of said stations, means at each of said stations for operating and maintaining in an operated condition the automatic switches at all of said stations and for operating only a particular one of said transmitting and printing mechanisms on said telegraph line, means at each of said stations for opening said line for a period ordinarily suff cient to insure the proper release of all of said switches, and means operated consequent to the full release of each switch to also open a point in the line circuit for a limited time interval to positively assure the release of all of. said switches.

OSCAR C. LEVY.

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