USRE22723E - Automatic message exchange - Google Patents

Description

E. E. KLEINSCHMIDT AUTOMATIC MESSAGE EXCHANGE SYSTEM Original Filed JanA 5, 1933 9 Sheets-Sheet l Feb. 19, 1946.

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AUTOMATIC MESSAGE EXCHNGE SYSTEM Original Filed Jan. 5, 1933 9 Sheets-Sheet 5 Feb. 19, 1946. E. E. KLEmscHMlDT Re. 22,723

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AUTOMATIC MESSAGE EXCHANGE SYSTEM 5. 1933 9 Sheets-Sheet 5 Original Filed Jan.

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AUTOMATIC MESSAGE EXCHANGE SYSTEM Original Filed Jan. 5, 1933 9 Sheets-Sheet 8 ATTORN Y ohm k Feb. 19, 1946. 5 E KLE|N5CHM1DT Re. 22,723

AUTOMATIC MESSAGE EXCHANGE SYSTEM Original Filed Jan. 5, 1935 9 Sheets-Sheet 9 an 804 600 602 C6,

l VENTOR ATToR Y Rescued Feb. 19, 1946 AUTOMATIC MESSAGE EXCHANGE SYSTEM Edward E. Kleinschmidt, Highland Park, Ill., as-

signor to Teietpe Corporation, Chicago, Ill., s

corporation oi' elaware Original No. 2,193,967, dated March 10, 1940, Se-

rial N0. 651,737, January 5, 1933. Renewed March 30, 1938.

Application for reissue May 15, 1940, Serial N0. 335,431

195 Claims..

The present invention pertains to methods of and means for handling telegraph trafc in a telegraph system comprising a plurality of interconnected central oiices and a plurality oi substations connected thereto and more specifically to an automatic telegraphic communication system.

The invention pertains also specically to automatic receiving, routing and delivering of telegraph messages, to automatic switching of telegraph lines, to automatic selection of telegraph lines. to automatic transmission, registration and retransmission of telegraph messages over telegraph lines which have been selected automatically, to transmission of an answerback message indicating delivery of a principal message, and to recording automatically information from which traiilc charges may be computed.

According to present telegraph practice in cities, a main or central telegraph oice is supplemented by many substation oilices which are connected to the central oillce by local telegraph lines equipped with automatic printing telegraph machines. These machines operate to transmit rnessages to the central omce for retransmission therefrom over intercity lines. Such a message is received in the central oilice by printing upon a tape which then is assigned to an operator in charge of a line extending to its destination, and then the message is retransmitted either by operation of a keyboard transmitter or by perforating a tape which then is passed through an automatic transmitter. The printed tape is physically transported from its location of reception in the central oilice to the location o! the retransmitting operator, and personal attention is required for the message in three separate instances; namely, by a receiving operator, by a physical carrying messenger or' mechanism, and by a retransmltting operator. If a message is destined for a station located at a distant central ofce. the present practice is for an address operator at the distant central station to receive the message on a printed tape. The printed tape is then physically transported to a sending operator who transmits the message to the station of final destination.

The principal object of the present invention is the provision of a telegraph system arranged to facilitate and expedite the transmission ci messages by the automatic establishment of communication circuits as determined by the addresses on the original messages.

A further object of the invention is to provide a system oi' telegraph central oihces and telegraph transmitting, receiving. recording, and retransmitting devices and with automatic line-switching devices such that the record of a message as received at its originating central oiiice will control automatic selective devices to set up a communication circuit from that central ofilce to the destination of the message.

Another object is to record a message in a form suitable for controlling its retransmission with the address portion thereof utilized to control automatic switches to connect a retransmitter over selected lines to the indicated destination, then retransmitting the message to the indicated destination. and then automatically returning a checking message to the point of origin to indicate the delivery of the message.

A feature of the invention is the provision of an automatically operative telegraphic checking system to increase the reliability of the trans mission of the address portion of the message.

A further feature is to provide recording devices to produce records o! transmitted messages from which charges for the service rendered may be computed.

A further feature is to provide means for automatically compiling and transmitting a return checking message when each principal message is received at its destination station, the return checking message being compiled automatically to comprise the signature of the principal message as an address for the return checking message and to comprise the address of the principal message as a signature for the return message.

A further feature is to route to a supervisory operator all messages having imperfect addresses or addresses not served by the provided automatlc switching facilities.

The above and other objects and features of the invention are accomplished by the arrangement of a telegraph communication system involving a plurality of central oilices to which are connected a plurality of branch stations and which are equipped with automatic switching mechanism permitting the automatic establishment of a communicating circuit between a branch station and its central omce, and between that central ofiice and other branch stations of a diierent central oihce. The establishment of the intercommunlcating circuit between the branch station and its central omce is effected through the operation of a calling key at the branch station which places that station in communication with printing telegraph apparatus, such as a reperforator located at its central oillce. Following this connection,

substations equipped with automatic telegraph the calling subscriber transmits the coded address of the called subscriber in duplicate, the body of the message, and the coded signature of the calling subscriber also in duplicate. Each of these portions is reproduced at the central station in a tape in the form of groups of perforations. This perforated tape constitutes a record form or control form for operating automatic switches to select circuits and for transmitting the message. The arrangement of the address o! the calling subscriber in duplicate code formation functions with a specially designed transmitter for determining the accuracy oi the perforation of the address, so that if an error appears therein a mechanism will be operated automatically for signalling an attending operator, who will receive the entire message on a receiving printer and make the necessary changes in the perforated record to permit the establishment of the originally intended communicating circuit.

Two sets of perforating apparatus are located at the central oillce, one ior urgent and the other for deferred messages which alternatively receive the message from the branch or calling station, and which cooperate with a specially designed tape transmitter for establishing the communicating circuit to the called station automatically in accordance with the perforated address in the tape. The selection of these perforators for operation is determined by the irst communication signal of the first letter of the code identified with the called subscriber.

The establishment of the communicating circuit to the called station is completed through the operation of selecting apparatus responsive to code combinations of impulses for completing circuits extending to the selector mechanisms allotted to particular branch stations within the area of the other central oilice or district where a iinal selector is operated for extending the communicating circuit to the called station. A mechanism is, of course, provided for seeking and seizing an idle trunk circuit extending between the central oices and apparatus is also arranged responsive to the selection of a busy line to indicate that condition to the operator at the central office of the originating subscriber.

If the line of the called subscriber is free, and provided an idle trunk between the central olces has been seized, the printing telegraph apparatus of the called station is connected in operative communication with the transmitting apparatus at the sending ofice of the originating subscriber. and the transmission of the entire message including the code address of the calling subscriber and that of the sender in duplicate is effected. Upon the completion of the transmission of the message and the transmission ot special designating groups oi code impulses, a mechanism responds to perforate a tape with the coded address oi' the original sender and that of the called subscriber, which is inserted automatically by the operation of apparatus prearranged with this address.

The thus perforated tape is subjected to a transmitter oi' the same general type as that by which the original message was transmitted, and coded impulses representative of the coded address of the calling and called subscribers will be transmitted to the calling subscriber over connections established automatically which will be received by the calling subscriber and serve as an indication that the message has been transmitted to and received by the called subscriber.

To provide for the automatic recording of messages from which service charges may be quickly and readily determined, a counting mechanism including printing elements is provided at each subscriber's station for automatically recording the address and the number o! words included in each message. From such a record the charge for services rendered in the transmission of the message may be computed.

A better understanding o! the invention may be had from the following description, taken in conjunction with the accompanying drawings, wherein,

Fig. 1 shows a diagram oi' the arrangement oi' circuits and apparatus of the system oi' this invention Fig. 2 shows a tape perforated with an address and part of a message for urgent transmission service:

Fig. 3 shows a tape, perforated with an address and part of a message for deferred transmission service;

Fig. 4 shows circuits in detail for the equipment of a subscriber line adapted to call the central oiilce and adapted to be called from the central ofiice;

Fig. 5 shows circuits in detail for the two alternative perforators, including message indicators:

Fig. 6 shows circuits in detail or address and message transmitters, a tape return device and circuits to a correction desk:

Fig. 7 shows circuits ot rst and second selectors and indicates circuits for trunking to other central offices in distant districts;

Fig. 8 shows circuits oi' third and fourth selectors and indicates circuits for trunking to ofces in the same district;

Fig. 9 shows circuits of an answerback system;

Fig. 10 shows circuits of a final selector;

Fig. l1 shows an arrangement o! other figures to produce a complete circuit diagram in which Fig. 4 appears at the left of Fig. 5 to show the calling substation and appears again dotted at right of Fig. l0 to show the called substation;

Fig. 12 shows circuits for an extended trunk to another office in the same district;

Fig. 13 shows plan view of parts of an accounting device;

Fig. 14 is an elevation and view of parts of the accounting device with detail of electrical circuits and,

Fig. 15 shows mechanical detail of a message indicating device.

GENERAL SYSTEM ron rm: DISTRIBUTION or MESSAGES Fig. l is a diagram showing an arrangement `of several types oi' switches used in transmitting a message from one substation to another substation within one central oiilce and'indicating trunk circuits for transmission oi similar messages addressed to substations in other central ofiices inY the same district as well as in other districts.

In Fig. l, substations Hi. Il, and I2 each has a receiving printer I3 and a transmitter I4 shown diagrammaticaliy, the circuits of which are shown in detail in Fig. 4. Each substation is connected by a line wire I5, I8, and I9 to an automatic trunk-finder switch i6, also shown in Fig. 4. Trunks il are communication wires which may be selected by the switch IB and each trunk Il is connected by wires 20 and 2| to two perforators 22 and 23. The details oi these perforators and the selective circuits and devices for rendering one or the other oi the perforators operative are shown in Fig. 5.

Each perforator is associated with an address transmitter 24 for retransmitting the address portion oi the message and a message transmitter 25 for retransmitting the entire message. comprising address, body, and signature portions of the message. Each assembly oi periorator and two transmitters, as 22, 24, and 25, has permanently associated with it an automatic trunk selector 26 or 21, which are shown in detail in Figs. 6 and 7 respectively.

Each or the selectors 26 responds to signals from the address transmitter 24 to set up a selective condition by which, nrst a group of trunks leading to a common destination is selected, then an idle trunk in that group is selected and seized, and the two transmitters 24 and 25 then are associated with the seized trunk and with its remote selector in a manner permitting the operation of the seized trunk and remote selector under control of the transmitter 24. Thus the perforator 22 and its transmitter 24 are adapted to operate their associated first selector 26 to seize a second selector 34 or 36, to operate the second selector to seize a third selector 40 or 42, to operate the seized third selector to seize a fourth selector 44, to operate the seized fourth selector to seize a fifth or final selector 50 or 52, and to operate the seized final selector to seize one of the three lines I5, I3, and I3 leading to the three substations I0, Il, and I2, respectively. The perforators and selectors here mentioned, all of which have been given labels of even numbers. are assigned to the service of urgent messages.

There is provided also separate equipment, perforator 23, Fig. 1, and associated transmitters, for service of deferred messages. Transmitter 24 of the set 23, 24, and 25 is adapted to operate its associated first selector 21 to seize a second selector 36 or 31 to operate the seized second selector to seize a third selector 4I or 43, to operate the seized third selector to seize a fourth selector 45, to operate the seized fourth selector to seize a fifth or final selector 5| or 53 and to operate the seized final selector to seize one of the three lines I5, I8, or I9 leading to the three substations Ill, II, and I2, respectively. The perforators and selectors here mentioned as assigned to the services of deferred messages have been given labels of odd numbers. The first, second, third, fourth, and iinal selectors are alike. Each final selector contains an answerback device 54.

To give preference to urgent messages over deferred messages in the system herein described, it is proposed that central ofllce attendants will assign sufficient trunk circuits both within the central offices and those connecting central oilices to urgent message transmission always to carry the trafllc load without delay. When the urgent traffic is heavy, the excess of deferred messages will be held in the form oi perforated tape at the transmitters until decreasing trame in urgent messages will permit the manual switching oi' trunk circuits to carry deferred messages. Keys |55, Fig. l, are for the purpose here described. While these keys are open. the trunks 60 and 6| may serve urgent messages only. While these keys are closed, the trunks 60 and 6I may serve both urgent and deferred messages. The keys |55 may contain contacts to make the trunkterminais busy-by-test in the selectors 35 and 31 while the switches are open, as shown at |56 in Fig. 7.

The trunk 6|| is provided with home communicating apparatus 62 and 64 and is connected with receiving apparatus 62 in another central oilice in a distant district. Details thereof are shown in Fig. 7. Trunk 6I is similarly equipped. Trunk 58 extends through home communicating apparatus 56 to receiving apparatus |56 in a nearby central oilice in the same district, Fig. l2, and trunk 59 for deferred messages is similarly equipped.

GnNxnAl. OPERATION Assume that an operator at substation Ill, whose telegraphic address is BOTIK, desires to send an urgent message to station I2, whose telegraphic address is BOTIE' for urgent messages. The operator depresses a calling key 30| at substation I, switch I6 responds in a well known manner and selects trunk I1 and its two perforators 22 and 23. A starting signal is shown at station ID and the operator proceeds to transmit the message. The two periorators 22 and 23 register the first signal of the letter B, and as the letter B is indicative oi an urgent message and not a deferred message, selective devices associated with the perforators 22 and 23 operate to render the deferred perforator 23 inoperative during the remainder of the message. The perforator 22 records address, body, and signature upon its tape. The operator then sends a message-end signal of blank code and central olllce apparatus acts to release calling line I5.

Beginning under control of the message-end signal code in the perforator 22, address transmitter 24 acts over trunk 66 Fig. 1, to register letter B upon the selector 26 and to connect transmitter 24 to trunk 68 of B group of trunks for urgent messages. The address transmitter 24 then acts over trunk 66 through selector 26 and over trunk 68 to register letter O upon selector 34 and to connect the trunk 68 to trunk 1|| of BO group of trunks. The address transmitter 24 then acts over trunks 66, 63, and 'Ill to register letter T upon selector 46 and to connect the trunk 1li to trunk 36 of BOT group of trunks. The address transmitter 24 then acts over trunks 66, 63, 13, and to register letter I upon selector 44 to connect the trunk III to trunk 'I2 of BOTI group of trunks. The address transmitter 24 then acts over trunks 66, 66, 10, 30, and l2 to register letter F upon nal selector 5|! to connect the message transmitter 25 of perforator 22 to line wire I9 and to substation I2 as identied by the address code BOTIF. The message transmitter 25 receives a signal that substation I2 is in condition to receive a message and immediately the message transmitter 25 sends the full message comprising address, body, and signature to the substation I2.

In the ilnal selector 5|| is an answerback device 54 shown in detail in Fig. 9, which is responsive to a signal code which precedes the signature. When this device is actuated, it operates to record the signature of the message, then to act as a sender to send to a perforator 14 a message comprising the recorded signature BOTIK as an address and the directory number BOI'IF of the connected line i9 as a signature. The transmitters I3 and 'I5 then control selectors 16, 34, 46, 44, 56 or similar selectors to select line wire I5 to substation III and a checking message BOTIK BOTIK BOTIF is printed at substation Iii to indicate delivery of the principal message at substation I2.

A record of the message for accounting or service charging purposes is made by a substauna device not snm in rig. 1 but shown in demi in Fiss. is and 14.

Tun Suasnnon um Irs Firman SwrrcH At the substation I l. Fig. 4, are telegraph sending contacts I4 and receiver magnet I3, shown diagrammatically. S boi I4 may represent a transmitter oi'any d, either keyboard contacts or automatic contacts controlled by a perforated tape. A motor 303 is provided for driving printer and transmitter. 'I'here is provided also a calling key 33| having ilve contacts. 'Ihe key 33| is adapted to be operated manually and to be held in operated position by a latch 302 which is also an armature of magnet 303. The latch 302 has an electrical contact 304 which engages to close a circuit when attracted by magnet 303. The magnet 303 is polarized and operates only when positive battery 33|, Fig. 5, at the central oilice is 300 has a pair of contacts 305 which are closed only when the motor is operated at full' speed and which are connected to terminals of resistance 306.

A relay 341 has its winding connected in circuit C.2, from power mains 3|0 through winding ot relay 301, and through top contacts of key 30| to mains 3|0, and has its amature and contact clonnected in parallel with the keyboard contacts 4.

An alternating current relay 3H, adapted to respond to current o! 135 cyclos, has its winding connected in circuit 0.30 from line wire |5 through magnet I3, a condenser 3I2, and contacts of key 30| to ground 3Il. It has its upper armature and contact connected in a branch of circuit 0.31 from line I5 through magnet I3. contacts I4, a resistance 303, winding and shunt 3|5 of a relay 3I3, upper amature and contact of the relay 3II and contacts of key 30| to ground, and has its lower amature and contact connected in circuit C 3 from the right-hand wire of the power mains 3I0, through the lower amature and contact of relay 3| I, and through the winding of a relay 3I4, a manual key 32|, an audible-signal device 3H, and a lamp 323 to the mains 3|0. The circuit C3 also may be completed through armature 302 ot magnet 303 and its contact 304. is of slow-to-release type, with its winding shunted by a non-inductive resistance 3|5, and has its winding connected in circuit C I, to the line wire and a contact of key 30|. This relay 3|3 is ot the well-known type which will maintain its contacts closed for a predetermined period either upon a cessation of current or upon a reversal of current such as a dashpot relay, a relay equipped with mercury operated contacts, or an alternating current, split phase slow-torelease relay. Its upper amature and front contact are connected to the fourth and ith contacts of the key III. Its lower armature and front contact are connected to the right-hand wire of the power mains 3Il and to one terminal of the motor 30| whose other terminal is connected to the left-hand wire of the mains 3| 0.

When the key 33|` is operated, its first contact engages its second contact and its fourth contact leaves its third contact and engages its nith contacts. The contacts oi relay 3|4 are connected in circuit CJ. from power mains 3|0 through contact and lower amature of relay 3|3, the armature and contact oi relay 3|4 and winding of relay 3I4, then as 0.3 to the mains 3|0. The winding of magnet 333 is connected in circuit C.|, from the fourth contact of key 30| to ground 303. The line wire 0,5 connects the substation I0 to apparatus at the central otlice.

At the central omce, an automatic switch I5 is individual to each line I5 and is adapted to connect the line I5 to an idle trunk, such as trunk wire |'I and its companion test wire 322. Switch I5 has two brushes which are driven by a ratchet 323 and a pawl 324 and an armature oi' a magnet 325, which has a return spring 325 and a pair of contacts 321.

Each line I5 has also seven relays, a switch relay 330 for controlling switch I6, a holding relay 33| for controlling a test relay 332 during transmission of a messagel a test relay 332 ior detecting an idle trunk test wire when the switch I6 is searching, a relay 333 for detecting a busyby-test condition of line I5 when line I5 has been selected by a nal selector, to be described, a relay 334 for cutting ofi switch I3 and its apparatus from line I5 after the line I5 has been seized by a final selector, a shunt relay 335 for shunting a choke coll 330 which is needed in setting up communication but is not needed after communication has been established, and a slow relay 366 for delaying restoration of line I5 to its battery 331 after the line has been released by relay 334 or by relay 33|. Battery 331 is common to a number of lines and is connected with its negative pole with the lines and its positive pole to ground. A grounded ringing generator 333 is connected in circuit C.36 through a condenser 333, normally open contacts of relay 334 and closed contacts of relay 335 to line I5, thence to ground 3|E as described above.

The battery 331 is connected in circuit CJ, through winding of relay 330, operating winding of relay 33|, and closed contacts o! relays 363 and 332 to the line wire I5, thence through magnet I3. contacts I4, resistance 305, winding and shunt of relay 3I3, lowest two contacts of key 30| normally open, and winding of magnet 303 to ground 303. The armature and front contact of relay 330 are connected in circuit C.4, with a battery 340 and winding of magnet 325. The contacts of the magnet 325 are connected to the ends oi the winding of the relay 330 to shunt this relay when the magnet 325 has attracted its armature. The holding relay 33| has its armature and contact connected in circuit 0.3. from test wire 322, contact 365 and brush 323, through the armature and contact and then through lower or holding Winding of relay 33|, lower winding of relay 360, winding of test relay 332, a resistance 34| and lower contact and armature of relay 333 to ground 342. Relay 332 has its top front contact connected to the communication brush o! switch I6. Its middle armature and front contact are connected to the terminals of resistance 34| to shunt that resistance. Its bottom armature and back contact are connected in busy-test circuit C35, to be described.

Associated with test wire 322 is a test-control relay 350, Fig. an upper or operating winding nected in circuit C.3, from negative pole oi' grounded battery 352, Fig. 5, winding of a` slowto-operate relay 343, upper armature and back contact of relay 35|, back contact and armature of the relay 350 and then through the upper winding o1' relay 350 to wire 322 and thence as described above for circuit C 3 to ground 342, Fig. 4. Relay 350 has a second winding of 1000 ohms, an external resistance 353 of 1000 ohms, and a dry copper oxide valve 354 whose resistance is 50 ohms when traversed by current from the battery of each trunk Il 5. This relay has of ohms con- 352. but is 5000 ohms when traversed by induced current from the lower winding o! the relay 330 in response to the beginning o! current in the upper winding of relay 350. The three elements 353, 354 and the lower winding oi' the relay 350 are connected in series and the terminals o! the series are connected to the armature and back contact of relay 350 so that the three series elements are shunted when the relay 350 is unenergized. The presence of the valve 354 reduces the induced local current and increases the speed of response when the relay 350 is operated by current through its upper winding.

Trunk wire I1 is connected in the primary communication circuit C.B. from positive pole ci grounded battery 33|, through winding of repeating relay 350, through contacts of relay 35| and through winding of relay 350 to wire I1, contact 355, Fig. 4. brush of switch I6, front contact and top armature of relay 332, line I and over circuit C.| to ground 3|0. Relay 353 has its upper winding terminals connected to upper amature and contact oi relay 304, which has its lower armature and front contact connected in circuit C.|5 to be described. Relay 353 has its lower or holding winding connected in circuit CJ, from contact of relay 35| in circuit C.3, through winding of relay 364, winding of relay 353, through the front contact (normally open) and lower armature of relay 350 to ground 303.

OPERATION or m FINDER SWITCH In this description, the elapsing time is divided into numbered intervals. The circuits also are numbered for easy identification.

Time -All apparatus in condition of rest The circuit C.| of the line i5 extends from battery 331 through relays 330 and 33| at the central ofllce, and is open for direct current at condenser 3|2, at the armature of relay 3|3, at the amature of relay 3| I, and at the fifth contact oi key 30| at substation i0.

Time I-Initiating a message The latching calling key 30| at the substation i0 in Fig. 4 is closed manually, i5 latched and closes circuits C.I and C 2, described above, the circuit C.| being extended to ground 303 through contacts of operated key 30| and winding o! magnet 303.

Battery 331 produces in circuit C.| a current of l0 m. a. which energizes relays 330, 33|, and 3|3 but not printer magnet I3 because the current is too weak, nor magnet 303 due to the connected negative terminal of battery 331.

Relay 3|3 in operating closes and shunts the fourth and nfth contacts of key 30|, and connects the power mains 3|0 to the motor 300. When motor 300 attains its operating speed contacts 305 are closed to shunt resistance 306. Energy from the power mains 3|0 produces in circuit C.2 a current to operate relay 301 whose contacts shunt the keyboard contacts |4 so that circuit C.| may be completed through the contacts of the relay 301 in case the contacts |4 be open.

Time Z-The period of search ,relay 332 and 1000 ohms in resistance 34|, or

a total of 2100 ohms, and the battery 352 of 110 volts produces an operating current o! 40 m. a., suillcient to operate the relays 349. 350, 300, and 332 and to hold the operated relay 33| The slowto-operate relay 343 will close its contacts eiectively only when the motor 300 does not reach lts maximum speed within a predetermined time limit.

Should switch I6 at this instant be holding test relay 332 connected through to an idle trunk test wire 322, relay 332 and relay 350 will be energized by current in circuit C.3. and the uplr armature of relay 332 will interrupt circuit CJ to release relay 330 to open circuit C.4 before magnet 325 has had time to step switch i6. Relays 332 and 350 jointly will render the trunk wire 322 busy-by-test. Should two testing relays 332 test the trunk Wire 322 simultaneously, the resultant resistance of circuit C.3 would be 1450 ohms and the current would be m. a. This is nearly double the normal current of relay 350 which would operate quickly and reduce the current through the two relays 332 neither of which would operate, and the search would continue as described below.

When a tested trunk wire 322 is busy-by-test, the resistance of circuit C.3 while being tested is ohms in relay 349, 1000 ohms in resistance 353, 50 ohms in valve 354, 1000 ohms in lower Winding of relay 350, 100 ohms in upper winding of relay 350, 500 ohms in winding of relay 33|, 500 ohms in winding of relay 366, and 500 ohms in winding of relay 332 at the finder switch I6. which is using the busy trunk. Connected in shunt of the last 1500 ohms above listed are elements 33|, 360, 332, and 34| at the switch I5 which is testing the busy trunk. The resulting resistance of the total circuit C.3 is 3187 ohms and battery 352 of volts produces a current of 35 m. a. of which the testing relay 332 receives but 13 m. a. which is sufilcient to hold relay 332 when operated. but relay 332 does not operate at this time to open circuit C.| and the relay 330 remains energized and holds circuit C 4 closed.

Magnet 325, energized over circuit C.4. attracts its armature and by the armature movement it drives the brushes of switch i0 into engagement with the next test contacts 355 and 365 thereof.

Should the second trunk be busy-by-test, relay 332 will not be operated. Contacts 321 operated by the armature of magnet 325 will shunt the winding of relay 330, thus deenergizing the relay 330 whose contacts then will open and will deenergize the magnet 325 thus opening the contacts 321. Again relay 330 will become energized to repeat the cycle to advance the brushes of the switch I0. When the brushes of the switch IB engage a wire 332 which is not busy-by-test, test relay 332 will receive 40 m. a. and will operate its armatures. Its lower armature and back contact will remove battery 345 from test wire 650 for incoming messages and will render line I5 busyby-test.

In the condition of rest (Time 0) circuit C.5. from battery 35|, winding cf relay 360, lower armature and back contact of relay 35|, upper armature and back contact of relay 355, resistance 362. to ground 363, has held repeating relay 300 energized.

The top armature and front contact of operated test relay 332 now close the primary communication circuit 6, but temporarily it is through magnet 303 to ground 303.

Current through the upper winding of relay 355 energizes the relay to operate its armatures.

Its upper armature opens circuit CJ and removes resistance 332 from circuit 0.3 and its lower armature closes the holding circuit C.1 thereby operating relay 334. Relay 334 shunts the operating winding of relay 333 from circuit C 3 but relay 333 is maintained energized by current in circuit C.1. Repeating relay 333 now is controlled by keyboard contacts 14 over circuit C l.

Magnet 333 unlatches key 331 which returns to normal position. Contacts in key 331 now shunt the winding of magnet 333, while other contacts thereof open circuit C.2 and deencrglze relay 3111.

Energization of magnet 333 has closed momentarily contact 334 to energize relay 314 over circuit C.3. Relay 314 holds by current over circuit C 3, lamp 323 glows and device 311 produces an audible signal. This is a signaling condition which notifies the operator of the substation I3 that the line is connected for transmission of a message. 'I'he same device will give an alarm when a message is received. The operator now opens key 321 momentarily to discontinue the signals.

The system now is in condition for transmission by the operator at substation 13, using keyboard contacts I4. Without normal speed in motor 333, contacts 333 remain open, current in line 13 is below normal and printer magnet 13 will not respond. This constitutes an automatic signal to the operator that transmission is not being effected.

Calling station 13 sends the first letter.' Signals enter the central oillce over circuit C.3 and operate repeating relay 333. Assume an urgent" message whose rst address letter is B" as shown in Fig. 2.

Tm: Panromrron SYsrlm For each trunk 11, Fig. 5, there are provided two perforators 22 and 23 of signal-controlled type in which perforation of a tape is effected with holes arranged in code formation to represent electrical signals which have been received in code manner by the perforator system. Such a device is generally similar to the device disclosed in Bulletin 1055 published by the Teletype Corporation, 1400 Wrightwood Avenue, Chicago, Illinois, to the device of Bulletin No. 143 of said Teletype Corporation which was published in 1930, and to the device disclosed, insofar as the perforator is concerned, in Patent No. 1,830,700. Such a device comprises tive signal receiving magnets 31|, 312 which operate ilve punch control fingers 313 which control ve code punches 314 with which is associated a fixed punch for feeding holes. A power magnet 313 operates the punches after code combinations have been set upon magnets 31 I 312. Tape feed is accomplished through the power magnet 313, a feed pawl, a ratchet wheel, and a pin wheel construction (not shown) cooperating with the feed holes in the tape 433 and operating in a manner generally similar to that disclosed in Patent No. 1,182,173 toC. L. and H. L. Krum of May 9, 1916.

With each perforator 22 and 23 is provided a distributor 313, 311, a tape follower switch 333, 331 and a message indicator 332, 333. These mechanisms are associated by circuits and relays, all organized to be controlled primarily by the repeating relay 333.

Distributor 313 has a stop segment 331, tlve code segments, a local switch 334, and a brush arm 333 with its brushes adapted to engage the segments and the local switch. Starting magnet 333 is normally energized to hold its larrrliiture 333 attracted. Armature 333 has an electrical contact 331 and has two mechanical stops for brush arm 333, a short-end stop for stopping the brush arm in normal position as shown and effective when the armature is in its attracted position, and a long-end stop for stopping the brush arm in a pre-normal position. In each of these positions the brush arm engages the stop :lament 331 and is disengaged from local switch Start magnet 333 is connected in circuit C.13 to stop segment 331 and arm 333 over wires 23 and 434 and contacts of relay 3311 to battery 433, and also over a common wire 332 through bottom contacts of relay 333 to ground 334. Start magnet 423 is connected similarly in circuit C.1|, from battery 433, contacts of relay 333, wires 434 and 21, arm 423. segment 421 and then wire 422 and contacts of relay 413 to ground 423. The five code segments of distributor 316 are connected in circuits C.12 and 0.13 by individual wires 331 to corresponding magnets 31| and 312, then to wire 332 for magnets 312 or through winding of relay 43 to wire 332 for magnet 31|. Contact 331 and armature 333 of magnet 333 are connected in circuit C.|4 through winding of relay 333 to battery 433 and over wire 43| to all armatures of perforator magnets 31| and 312, thence through circuits C.|2 and C.|3 to ground 334. Switch 334 is connected on one side through winding of test relay 432 to battery 433, and on the other side to winding of perforator power magnet 313 and through the bottom contacts of blanking relay 433 to common wire 332 and ground 334, thus forming circuit 0.13.

Tape follower switch 333 when in normal position with tape 433 slack as shown, comprises normaily closed contacts 4111 connected in circuit 0.33, to be described, and normally open contacts 433 connected to ground and to winding of relay 433 which is connected through middle contacts of relay 413 to battery 433, thus forming circuit C.43. The top amature and contact of relay 433 are connected in circuit C.42 with battery 41 I, interrupter contacts 412 on magnet 413 and the winding of magnet 413, and the middle armature of this relay is connected to ground with its front contact thereof connected through resistance' 414 to the trunk test wire 322, forming a branch path for busy-test circuit C.3. Vibrator magnet 413 has also a pair of contacts 413 operated by its armature and connected through winding of power magnet 315 and through lowest armature of relay 433 and its front contact to ground, and connected also through middle contacts of relay 413 to battery 433, thus forming circuit C.43 when relay 433 is operated. These contacts are normally open and are closed when the magnet 413 attracts its armature. Relay 413 has a lower locking winding which is connected from grounded wire 332 and through its own upper amature and contact and through the lower contacts of relay 334 to battery 433, to form circuit 0.15, which when formed holds the relay 413 energized through the transmission of the complete message. Magnet 413 also is included in circuit 0.13 in parallel with the holding winding of relay 413.

As shown in Fig. 15, a message indicator 332 includes a fixed shaft 433 which carries two rotatable ratchets 43|, each of which carries one contact of the pair 433 and a collector ring 423. Contacts 433 and rings 423 are assembled upon ratchets 431 with insulating rings and hushed screws. Brushes 423 engage collectors 423 and are connected to battery and to the winding of relay 432, Fig, 5, forming circuit C.2|.

Perforator 23 is identical with perforator 22 except in the circuit connections, which are rcversed in two details. In perforator 22, current through first magnet 31| (C.|2) energizes control relay 4 I3 while in perforator 23, current through first magnet 424 does not energize relay 333 oorresponding to relay 4|3. In perforator 22, current through magnets 312 (C.|6) does not energize relay 4|3 while in perforator 23, current through magnets 425 will energize relay 393.

Discrimination thus is effected between urgent messages and deferred messages. An urgent message (Fig. 2) will operate relays 31| and 4|3 to remove ground 423 from wire 422 and from all operating circuits of perforator 23, thus disabling perforator 23 and permitting perforator 22 to record an urgent message, While a deferred message (Fig. 3) will not operate relays 31| and 4|3 but will operate a relay 425 and relay 333 to re move ground 334 from wire 332 and from all operating circuits of perforator 23, thus disabling perforator 22 and permitting perforator 23 to record a deferred message.

Cut-off relay 35| has its winding connected to battery 352 and also through the contacts of de.. tector relay 336 and contacts of message-end test relay 432 to ground, forming release circuit C.|3.

OPERATION or Pnarona'roa SYSTEM Assuming that calling station I3 has been connected to repeating relay 363 over circuit C.6, and that the llrst letter of the address is B, the operation will be as follows:

Time .'i-Selectilng the perforato'r In idle condition of waiting, the two perforators 22 and 23 have their starting magnets 336 and 423 continuously energized over circuits C.|3 and C.|| for the urgent and deferred messages.

A starting impulse preceding a code for letter B deenergizes repeating relay 333 and interrupts both circuits C.|3 and C.||, deenergizing both start magnets 333 and 423, and releasing both brush arms 335 and 426 in both perforators 22 and 23. The first signal of code for letter B is a marking signal which energizes repeating relay 363 and operates it to close its contacts. At this instant the arms 335 and 423 are in engagement with' their No. 1 segments and circuit C.|2 is completed.

Relay 4|3, energized by current in circuit C.|2, operates its armatures to interrupt all operating circuits in perforator 23. Relay 4|3 and magnet 31| close holding circuits C.|4 and C.|5, but the movement oi the armature of magnet 4 I 6 is without eilect at this time.

Time 4-Perforating ing circuit C.|4, thus registering upon the set of magnets 31| and 312 the code for letter B.

Brush arm 335 closes circuit C.|3 through switch 334 as traced above to operate magnet 315. Magnet 315 operates its armature thereby perforating tape 436 by punch pins 314 with the code of letter B and the mechanism of the perrorator steps the tape 436 into position for a succeeding perforation, as is fully described in the patent refen-ed to.

Brush' arm 335 of perforator 22 engages segment 331 and closes circuit C.|3 to energize magnet 336 and brush arm 335 then stops in its normal position in mechanical engagement with the short end of armature 333. Brush arm 423 in perforator 23 engages segment 42| but does not close circuit C.|I to energize magnet 423 because common wire 422 is open in relay 4|3. Brush arm 426 therefore stops in mechanical engagement witn the long end of the armature of magnet 423 and remains in that position until circuit C.|I is closed by deenergization of the relay 4|3 at the end of a message.

Reenergization of starting magnet 333 moves armature 333 from its contact 33| and interrupts holding circuit C.|4, deenergizing detector relay 336 and deenergizing all magnets 31| and 312. This completes the cycle of the rst letter, leaving relay 4| 3 and magnet 4|6 energized by circuit C.|5, brush arm 423 oit-normal and common wire 422 open in relay 4| 3.

Time 5-Subsequent codes except "blank code Each subsequent code repeats the operations of time 3 and time 4, except that relay 4|3 remains operated, magnet 4I6 remains operated and brush arm 426 is not started. The operator at substation |3 transmits the duplicate address, the message body, an answerback cut-in signal code, and a duplicate signature comprising in duplicate the directory code of the substation I3, then sends blank code as a message-end signal.

Time -Message-end signal In response to "blank code, a starting impulse releases relay 333 which opens circuit C.|3, and brush arm 335 starts, engaging segments Nos. 1 to 5 successively, but contacts of relay 363 are open for all ilve signals in blank code and no current ows in circuit C.|2 or circuit C.|6 to energize any magnet 31| or 312 nor is detector relay 336 energized. Brush arm 335 closes circuit C.|3 to operate magnet 315 and message-end test relay 432. The tape is then advanced one step to present an unperforated area of tape opposite punch pins 314 and contact of relay 432 closes message-end circuit C.|3 momentarily. Relay 35| is energized and when operated it holds its armatures two seconds after current ceases.

Repeating relay 363 is maintained energized by a circuit through contacts of relay 35| and resistance 358 to ground. Communication circuit C.6 is opened at the lower armature of relay 35| thus deenergizing relay 3|3 at substation 3. Circuit C.3 is opened at the upper armature of relay 35|, thus deenergizing relays 343, 353, 33|, 366, 332 0f circuit C.3 and relays 364, 356 of the associated circuit C.1. Slow-to-reiease relay 366 holds line i5 open from battery 331, after relay 332 has released its top armature and until after slow-to-release relay 3| 3 has released its armature.

After one-quarter second from operation of relay 35|, relay 3|3 releases its armatures. Motor 333 stops and an accounting device, Fig. 14, operates.

After one-half second from operation of relay 35|, relay 366 releases its armature, thereby restoring line |5 to normal condition of idleness.

Two seconds after operating, relay 35| releases its armatures. The upper armature and back contact close test circuit CJ to render trunk |1 and its wire 622 idle-by-test.

Deenergization of relay 564 opens holding circuit C.|5 deenergizing relay 4|0 and magnet4|6. Deenerglzation of relay 4|0 connects wire 422 to ground 426 and closes circuit C.|| to energize magnet 420 to permit brush arm 426 to advance to normal position. Deenerglzation of magnet 4I6 permits its armature and pawl to drive ratchet 45| one step and thus separate the contacts 435 and open circuit 0.2i to deenergize relay 462.

Rs'rnlmsmssron APPARATUS For checking codes of a repeated address for accuracy, a double tape-reader is provided to read the two parts of a repeated address simultaneously and to compare the two readings (Fig. 6). A friction driven shaft 440 carries contact-operating cams 44|. 442 and a cam 443. Cam 44| operates contacts 444 to close when cam 44| is ofi normal, and cam 442 operates contacts 445 and 446 to close when cam 442 is from 45 to 190 of rotation. Cam 443 operates cam follower 441 to lift it from ten bellcranks 45| operated by springs 452 so that a set of ve principal feelers 453 and a set of five auxiliary feelers 454 cooperate with tape 406 which was previously perforated by the mechanism 22, Fig. 5. The distance between sets ol' feelers is such that perforations for two first letters of the repeated address may be engaged by two sets of feelers at the same time. Another shaft 455 with a feed wheel 456 steps tape 406 for each operation. Shaft 455 carries a ratchet wheel operated step by step by a pawl which is normally out of engagement with the ratchet wheel and which is moved through a suitable cam to engage a tooth of the ratchet wheel to rotate shaft 455 and wheel 455 and thus to step the tape 406 a distance of one character space or one transverse row of perforations. When any principal feeler 453 passes through a perforation in tape 406 it operates a rocker, such as 460, against tension of its spring 46| to close a switch 452, closing circuit C.26 from battery 490 to ground, to operate one of ve multi-contact code relays 41 I, 412, 413, 414, and 415. When any auxiliary feeler 454 passes through a perforation in tape 406 it operates a rocker, such as 463, against tension of its spring 464 to reverse one of five switches 466, 461, 466, 460, and 410. Each of these switches has its two contacts connected in circuit C.30 to be described, to contacts of a fifth armature of a corresponding code relay 41| to 415. Cam contacts 444 are connected from ground through the winding of a transmission cut-out relay 416, and through contacts and all first and second armatures of all code relays 41| to 415 to battery 490, forming circuit C25, also through lower armature and contact of relay 415 and through winding of magnet 505 to battery and ground, forming circuit C25, while cam contacts 446 are connected in circuit C26 with contacts of a relay 411. lamp 460, winding of relay 46| and battery 462, and cam contacts 445 are connected in circuit 0.30. over wire 464, through all iifth armatures of code relays 41| to 415, and through all switches 466 to 410, through the winding of test relay 465, the upper back contact and armature of relay 416, battery 5| I, winding oi' relay 411 and right-hand winding of magnet 463. A branch wire connects wire 464 to the front contact of relay 416, forming a shorter circuit 0.21, containing only the contacts of relay 416, battery 5H, Winding of relay 411, a winding of magnet 466 and contacts 445. Shaft 440 also carries stop arm 466 which is stopped at normal position by an armature of a switching start magnet 461 but is cleared when magnet 461 is energized to attract its armature. Arm 466 may be stopped at its 60 position by an armature of stop magnet 463 but is cleared when magnet 463 is energized to attract its amature. Shaft 440 advances feelers 453 and 454 to test tape 406 during the first 45 of its cycle and during the last 170 of its cycle it withdraws the feelers and operates shaft 455 through the ratchet and pawl mechanism to step tape 406. The ratchet wheel feed pawl is, prior to the end of the cycle oi shaft 440, moved free of the ratchet wheel.

In each code relay 41| to 415, its third armature is the message transmitting armature in circuit C.31, and is connected over common wire 49| to the battery 490 and each such armature has its front contact connected over an individual wire 462 to a corresponding segment of distributor 25. In each code relay, its fourth armature is the address-sending armature and is connected in circuit C.3| over an individual wire 463 to a corresponding segment of the distributor 24, with back contacts of those armatures connected to positive battery 464 for transmitting spacing signals and with front contacts of those armatures connected to negative battery 465 for transmitting marking signals. All sixth armatures of the code relays 41| to 415 are connected in multiple to the battery 466 and all front contacts thereof are connected through the winding of relay 461 to the battery 466, forming circuit C14.

Shaft 455 carries also a pinion wheel 500 with which is associated means for returning tape 406 after transmission oi an address so that the address may be transmitted again. A tape-return solenoid 50| has an internal amature 506 to which is pivotally attached a rack 502 which cooperates with pinion wheel 500. A striker arm 503 is fixed upon the armature 506 of magnet 50| and operates to close a switch 504. Cooperating with rack 502 is a bellcrank armature 506 operated by a magnet 505 and a spring 501. Armature 506, rack 502, and pinion 500 are so related that the armature may depress the rack into engagement with the pinion or may effect their disengagement, the rack may be returned by solenoid 50| from any position to which it has been advanced, the wheel 500 may turn freely of the rack when the rack is lifted, and the rack and pinion engage each other, either to operate the other, when the rack is depressed by the armature. A short forward motion of the rack will engage it under a fixed detent 529 and a further movement causes it to engage and operate armature 506 of a magnet 5I0. The functions of the device will appear in the description of its operation. Solenoid 50| has its winding connected in series with battery 5I2 and contacts of a relay 5I3, circuit 0.23, and also in series with battery 5|2, wire 656, winding of a magnet 5I4 in message indicator 362, Fig. 5, wire 651, bottom contacts of relay 5I5, and wire 656, circuit C.36.

Address transmitter 24 comprises a distributor having five code segments, a normal segment 5|6 and a brush arm 5I1. Normal segment 5|6 is connected in circuit 0.22, through lower armature and back contact of test relay 465 to the right-hand terminal of resistance 520 and also is connected through the winding of magnet 518 and armature and iront contact of test relay 485 to the left-hand terminal of resistance 528 and thence through contacts of relay 432 in message indicator 382, Fig. 5, and contacts of relay 48|, Fig. 6, through back contact and lefthand amature of relay 522, and through winding of magnet 481 to battery 528 and ground 52|. Relay 48| has its armature connected also through contacts oi.' relay 522 to battery and ground. Circuit C.22 extends also from brush arm 1 through back contact and armature of magnet 518, upper winding of relay 5|3, contacts of slow relay 523 and top contacts of relay, 5I! to wire 524.

Message transmitter 25, Fig. 6, comprises a distributor containing live code segments, a normal segment 525 and an unconnected startingsignal segment 526, also a. local switch 521, a brush arm 538 for engaging the commutator segments and for closing the local switch. and a start magnet 58|. The brush arm 538 is carried -by a shaft 532 which carries also a cam 533 which normally holds depressed ilve pivoted members 534, Fig. 6. In its rotation, cam 533 frees the five members 534 and permits them to rise under tension of their ilve springs 535 to lift feelers 453 against or through tape 486.

The magnet 53| is connected in circuit 0.39, from one terminal through contacts of relay 523 to battery 536 and from the other terminal through wire 668. switch 584, wire 66|. switch 481, Fig. 5. wire 682 and contacts of relay 5|5 to battery 536.

The local switch 521 is connected in circuit 0.24 in series with battery 496 and the winding of relay 491 and the normal segment 525 is connected in circuit C31, from battery 490, segment 525, arm 538, and lower winding of relay 5I5 to wire 66 which extends into Fig. 7. Test relay 5|5 has its upper winding connected to its top amature and back contact in circuit 0.22 and has its lower winding in circuit C.31 connected to its second amature and front contact. The winding of the magnet 5I8 is connected to the battery 531 and to the front contact of the armature 589 in an alternative branch of circuit C12, while lower winding of relay 513 is connected from battery through contacts of relay 48| to ground.

Apparatus is provided for receiving at an attendants desk any message in which the repeated code address does not check identically and also messages with addresses not in code. A receiving instrument 548 is connected to a manual plug 54|, and a manual jack 542 is adapted to connect to wire 65 the receiving instrument 548 forming an alternative branch of circuit (7.31. When the plug has been inserted into the jack, a pair of contacts 543 adapted to be closed by insertion of the plug in the jack are connected in series with the winding oi' the relay 522, the left-hand winding of the stop magnet 483, and battery 544.

SELECTOR APPARATUS Each selector 26 to 41 inclusive, Fig. 1, see selector 26, Fig. 7, comprises ve notched code bars 55|, 552, 553, 554, 555 and a plurality oi detector bars or letter bars, A. B, Y, Z and others which; overlie the code bars and drop into the notches of the five code bars when five notches are aligned under any letter bar. A locking bar 558 holds up all letter bars or releases all letter bars so that one of them may drop into aligned notches in the code bars. Each code bar may be operated by a polar magnet 558 to 588 inclusive and the locking bar 558 may be operated by a magnet 56|. Each such selector has also a distributor comprising tive code segments, 1 to 5 inclusive, with grounded segments between, a resistance segment 562 with resistance 563, holding segment 564 and a normal segment 565, also a local switch 566. A brush ann 518 engages the commutator segments in order and also engages and closes switch 566. The brush arm stops by engaging mechanically either the long end or the short end of an armature 51| of a starting magnet 612. The starting magnet 512 is marginal, will not operate its armature with a current of 30 m. a., will operate its armature with a current of 60 m. a.. will hold its armature with a current of 10 m. a., and will hold its armature through a polar reversal with currents of 30 m. a. Electrical contacts 513 in the nature oi relay contacts are provided for the letter bars, each letter bar closing four pairs of such contacts. One Contact of each such pair is connected to a common wire 588, 58|, 582, or 583, common to all letter bars, and

the other contact of the pair is connected to a wire of a group individual to the letter bar, as 585, 586, 581, and 588. When a letter bar operates to close its contacts, the pair of contacts of the wire 581 closes before the remaining three pairs. An incoming signal wire 524 associated with trunk wire 66 is connected through the winding of starting magnet 512 to brush arm 518. The ve code segments of the distributor are connected by five individual wires to the ve code magnets 556 to 568 inclusive, and the intervening segments and normal segment 565 are connected to ground 598. Segment 562 is connected through resistance 563 to ground 598. Holding segment 564 is connected to a contact of the middle armature of relay 59|. One contact plate of the local switch 566 is connected to ground 598, while the other plate is connected through the winding of magnet 56| to grounded battery, forming circuit C 32. When brush arm 518 stops in holding position. circuit C.32 is held closed, and wire 524 is held connected through the magnet 612 to holding segment 564 and thence to contacts of relay 58|, resistance 594 and ground, forming an extension for circuit C.22.

The winding of a test relay 59| is connected from common wire 583 to ground through resistance 592 and through wire 583. letter-bar contacts as 513, wire 588, brush 688 in switch 688, wire 613. relay 614 and battery 634, forming circuit C34. The top armature and front contact of relay 59| are connected to resistance 592 and to ground, the middle armature is connected through the winding of relay 593 to common wire 58|, and through letter-bar contacts to brush 886 in switch 688. and the bottom armature and back contact are connected to ground and to common Wire 582 and through contacts as 513 and winding of magnet 681 to battery, forming circuit 0.33. The armature and front contacts of relay 593 are connected to common wire 588 and to incoming trunk wire 66, to extend circuit 0.31.

Each group of letter-bar wires, as 585 to 588, extends to a rotary searching or finder switch 688 of which there may be one i'or each letter bar. Each switch 688 comprises a set of rotary brushes, a iield of fixed contacts for the brushes, and an electro-magnetically controlled power means for driving the brushes. A continuously driven power drum 68| is located near a brush drum 682 fixed on a brush shaft 883 which carries three brushes, a brush 585 connected to wire 585, a brush 888 connected to wire 585, and a brush 888 connected to wire 588. A clutch magnet 881 has an armature and crank arm 8I8 with an idler friction wheel 8l I. When magnet 881 attracts its armature 8I8 the wheel 8II is moved to engage both drums 88| and 882 thus driving brush shaft 883 and the three brushes.

The trunks among which the switch 888 searchers comprise each three wires, a communication trunk wire, as 88 connecting switch 888 to selector 34, an accompanying signal wire as 8I2 corresponding in the second selector to wire 524 in the first selector, and a local busy test wire 8I3 connecting switch 588 to the test-control relay 8|4 the same as relay 358 of circuit 0.5 in Fig. 5.

THE FINAL SELECTOR A nai selector 58, Fig. 18, is mechanically similar to selector 28 except that the letter bars close only three pairs of contacts, there is no searching switch, and the relay arrangement is di'erent. A test relay 828 corresponds to the test relay 59|, Fig. '7. Relay 82| corresponds to relay 583 but is connected in an individual signal Wire of each letter bar rather than in a signal wire common to al1 letter bars. The test wire to be tested for selection is not equipped with a relay such as 8I4, Fig. '7, but extends to the relay equipment oi' the line as shown in Fig. 4.

OPERATION OF SELECTORS The operation of the selectors is started by deenergization of relay 432 in message indicator 382. Fig. 5. which occurs when the message-end signal of blank code is received by perforator 22. 'I'he amature and back contact of relay 432 close the switch starting circuit C.22, extending as described, from ground 52|, Fig, 8, to wire 524 and now to magnet 512, Fig. 7, of first selector 28, brush arm 518, normal segment 585, to ground at 588. When this circuit is completed, magnet 481 is operated and the operation of its armature releases arm 488 and friction-driven shaft 448 starts. Cam 44| closes the contacts 444 to form circuits C.25 and C.28, as traced above.

During idleness. the holding circuit 0.23 has held energized the solenoid 58|, Fig. G. Current in circuit C.22 now energizes and operates relay 518 to open the holding circuit and to deenergze the solenoid 58|.

Also during the period oi' idleness the holding circuit C.24 is held closed by local switch 521 in distributor 25 thus holding relay 481 energized and holding its contacts open to maintain relay 523 unenergized. These conditions now continue.

Time 7-Blank-tape clearing In the condition of idleness which preceded the seizing of trunk I1 by substation I8, tape 488 was blank, containing feed perforations but no code perforations, from perforator punches 314 to feelers 458. This distance is but a few inches but code perforations of the received message now are preceded in tape 488 by tape which is blank other than for feed perforations. Feelers 453 therefore have been released by cam 443 but have not risen through tape 488 because of the absence o! any code perforations. The tape 488 therefore tests blank to feelers 453 and crcuit C.28 as traced above may be formed, which energizes relay 418 and opens circuit C.25.

Cam 442 closes contacts 445 and forms the transmission cut-out circuit C.21, energizing magnet 483 to permit arm 488 to pass without energizing magnet 5I8 for transmission. Cam 442 also closes contacts 448 to i'orm circuit C.28 to energize lamp 488 but current in circuit C.21 energizes relay 411 to open circuit C.28 so that lamp 488 does not glow.

Circuit C.22 holds magnet 481 energized and circuits C.28 and C.21 are completed at each rotation of shaft 448. until all blanks in the tape as well as letters or unshii't" codes have been fed past feelers 453 and code holes are encountered by those feelers.

Time s-Operation of the )lrst selector The first letter of the address of the message reaches principal teelers 453 and the same letter repeated reaches auxiliary feelers 454. Circuit C.22 remains closed and magnet 481 remains operated to pass arm 488 without a pause.

Tape 488 is perforated as shown in Fig. 2. The two sets of feelers 453 and 454 respectively are separated by a distance equal to six steps o1' tape 488 so that when rst letter B of the address of the message is in position to be read by feelers 453, second letter B of the address of the mesage is in position to be read by i'eeiers 454 as a check upon the accuracy o! the address codes.

Shaft 448 rotates and approaches the armature of magnet 488. Cam 443 permits a set of five feelers 458 and a set of auxiliary feelers 454 to rise to test the tape for code eombinatirmr` of perforations. The first, fourth, and fiith feelers 453 and the first, fourth, and fth feelers 454 pass through tape 488 and close their associated lower contacts. Relays 41|, 414, and 415 are energized over their three circuits (1.29 in accordance with the code for letter B.

Cam 44I closes contacts 444 to form circuit C.25 and magnet 585 is energized. Circuit C.26 is not formed because at least one code relay is energized. Cam 442 closes contacts 445 to form circuit 0.38, traced above. Relays 485 and 411 and magnet 488 are energized. Relay 411 opens the lamp circuit. Test relay 485 substitutes magnet 5|8 for the resistance 528 in circuit C.22, thus reducing the total resistance of this circuit and increasing the current in the circuit to 68 m. a., operating the magnets 5|8 and 512. Magnet 483 attracts its armature and clears the path for arm 488.

The speed of brush arm 5I1 is double that of arm 488. Therefore, while shaft 448 rotates from its 45 position to its 198 position the brush arm 5I1 will reach position 290 on segment 5I8. The distributor arms 8|1 and'ElI however move in unison and are released upon the energization of their start magnets.

When brush arm 5I1 leaves normal segment EIB, circuit C.22 is interrupted and magnet 481 is deenergized. Address signal transmission circuit C.3| is traced above then is eilective live times, for each marking signal through negative battery 485, and for each spacing signal. through positive battery 494. The magnets 558 to 588 are thus energized in polar manner and in a code combination.

The code for B now has been set on first se lector 28. When brush arms 5l1 and 518 reach the position of 290, the arm 488 is at 190. Contacts 445 are opened. thereby interrupting saves circuit 0.88 and deenergizing relay 485. Arms 5|1 and 518 interrupt circuit 0.3i by leaving their No. 5 segments and form circuit 0.22 by engaging their segments 5|8 and 582 respectively.

At this time circuit 0.22 extends from ground 52|, through battery 528, Fig. 6, through unenergized magnet 481 and resistance 528, segment 5|8, brush arm 5|1 in motion, upper winding of relay 5|3, wire 524, energized magnet 512, Fig. 7, brush arm 518 in motion, segment 582, resistance 583, to ground at 598, with a current of l m. a. owing therethrough. Brush arm 518 in selector 28 engages mechanically the long end of the armature of magnet 512 and stops at its 315 position, thus switching circuit 0.22 from segment 562 to holding segment 584 whence this circuit extends through contacts of the middle armature of relay 58| and resistance 594 to ground. The current remains 10 m. a. because of the resistance 594, substituted for resistance 583, but brush arm |1 stops at its normal position without changing the circuit. Magnet 481 now has l0 m. a.. which is not sufficient to operate its armature and relay 5|3 has 10 m. a. and holds its amature as does magnet 512.

At the time of engaging segment 562. brush arm 518 also closed local switch 566 and therefore closed circuit 0.32, causing the energization of magnet 56|. Locking bar 558 is consequently operated and mechanically unlocks all bars of the set of letter bars having code relation with the code bars 55| to 555. The code relation is such that when the predetermined code, as B, is set upon the code bars 55| to 555, the letter bar B will be unrestrained by any bar 55| to 555 and all other letter bars will be restrained from movement to close their electrical contacts. As now described. code bars 55| to 555 are set for code B and locking bar 558 is operated to unlock them. Bar B is not restrained in any way and therefore moves and closes its electrical contacts. By this selection and operation of letter bar B, the four common wires 588, 58|, 582, 583 of the selector 25 have been connected to searching switch 588 by connecting them to the individual wires 585, 588, 581, 588, which starts to rotate when the first contact is completed to establish circuit 0.33,

Searching switch 888 now is rotating and letter bar B closes all contacts, closing the testing circuit 0.34. The action in the circuit 0.34 is identical with the action in the testing circuit 0.3. Busy trunks give to the brush 688 a current insufiicient to operate the test relay 59|, While an idle trunk gives current sucient to operate relays 58| and 6|4. Should two relays as 59| test the same trunk wire as 8|3 at the same time, the relay 6|4 would operate and the searching relays would not operate, Both searching relays would reject the trunk as busy and both searching switches would continue to rotate. When an idle trunk has been found, relay 59| operates its top armature to shunt the resistance 592 and relay 8|4 is energized to render the wire 8|8 busyby-test. Relay 58| operates its bottom armature to open the drive circuit 0.83 and the nder switch 588 stops in engagement with the tested and seized trunk 68. Relay 59| also operates its middle armature to switch circuit 0.22 from the resistance 594 and to extend this circuit from the holding segment 584 through the middle armature and front contact of relay 59|, through winding of relay 593, contacts of letter bar B, brush 886 and contact in switch 888, wire 8|2 to selector 34, magnet, distributor arm and normal segment to ground 885.

When the circuit Just traced is established, relay 583 operates and connects wire 88 to wire 588 and thence to wire 585 thus effecting the first step in building up the message transmission circuit C.3| to be described.

The current now flowing in circuit 0.22 and its first extension to the second selector, increased by removing the resistance 594, is approximately 30 m. a. which energizes switch starting magnet 481 to operate its armature for the second letter of the address, to be registered upon the second selector 34.

At the instant when relays 59| and 8I4 operate, arm 488 is approaching the armature of magnet 481 if the search of switch 888 has been short, as is in mechanical engagement with the armature of magnet 481 if the search of switch 588 has been long. During the period of the last of shaft 488, feelers 453 and 454 have been withdrawn from tape 488, then shaft 455 has been turned to advance tape 488 and rack 582 one step. Return of feelers 453 has opened switches 462 to deenergize all relays 41| to 415 thus forming circuit 0.28 to energize relay 418 which opens circuit 0.25 and deenergizes magnet 585, but the slow-to-release armature of magnet 585 holds rack 582 in engagementV with wheel 588 long enough to permit wheel 588 to step the rack and to engage the end of the rack under the stud 528. This action has advanced tape 486 to present the next two sets of code perforations to the two sets of Ieelers 458 and 454.

Time B-B-Defectve address A message having a. defective address, or in which the code address has not been repeated, will be sent to an attendants desk and the attendant then will correct or complete the address and will forward it by the automatic selecting and transmitting devices.

Should any letter of the address not correspond to its companion letter, test circuit 0.38 will not be formed between code switches 488 to 418 and corresponding code relays 41| to 415, Stop magnet 483 is not charged by circuit 0.38 and arm 488 stops at 60 in mechanical engagement with the amature of magnet 483. Cam contacts 448 close lamp circuit 0.28, relay 411 is not energized by circuit 0.38 and lamp 488 glows to signal the attendant. Relay 48|, energized by current in circuit 0.28, opens circuit 0.22, deenergizing magnet 512 in all selectors, thus restoring all selectors, and deenergizing relay 5|3, thus energizing solenoid 58| to return tape 486 to its starting position.

'Ihe attendant noting the signal inserts plug 54| into jack 542. Jack contacts 543 close a circuit including battery 544; left-hand winding of magnet 488 and the winding of relay 522. which causes magnet 488 to attract its armature and permit arm 488 to start from its 60 position. The left-hand armature and back contact of relay 522 open the winding of magnet 481 and arm 486 will stop at normal and cam 442 will open lamp circuit 0.28. Circuit 0.22 now is formed from ground and battery through contacts of relay 522 instead of through magnet 481, and extends to wire 824 and to ground 588 in selector 26 with a current of 30 m. a. which will not operate magnet 512 in the selector.

Switch 548 is normally open. After inserting the plug 84| and when the lamp 488 has been extinguished, the attendant closes the switch 548.

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