US2357297A - Printing telegraph system - Google Patents

Description

P J.- E. wAcK ETAL I PRINTING TELEGRAPH SYSTEM Filed July 13, 1940 2 Sheets-Sheet 1 FIG.'1

INVENTOR. JAMES E WACK WALTER .1. ZENNER ATTfiEY.

Sept. 5, 1944. J. E. WACK EIAL PRINTING TELEGRAPH SYSTEM 2 Sheets-Sheet 2 I56 2IO Filed July 13, 1940 INVENTOR. JAMES E. WACK WALTER J. ZENNER Patented Sept. 5, 1944 2,357,297 PRINTING TELEGRAPH SYSTEM James E. Wack, Chicago, and Walter J. Zenner, Des Plaines, 111., assignors to Teletype Corporation, Chicago, lll., a corporation of Delaware Application July 13, 1940, Serial No. 345,260

12 Claims.

This invention pertains to telegraph systems and particularly t such systems designed for the propagation in broadcasting manner from a central station to a plurality of substations Fig. 1 illustrates a transmitter for formal messages;

Fig. 2 shows details of key construction;

Fig. 3 shows a general circuit diagram of the of messages varying principally in content rather 5 central oflice system which should be placed dithan in form.

An object of the invention is to providea transmitter which includes settable apparatus for predetermining a message form, supplemented by settable apparatus for inserting into a formal message certain character signals as will convey specific information.

In combinationwith the indicated principal transmitter for formal messages, a subordinate transmitter for messages of unlimited content and free of restrictions of form is provided.

A further object of the present invention accordingly is to provide locking devices and interfering devices such that a principal transmitter may seize the transmission system in preference to a subordinate transmitter and may continue uninterruptedly the transmission of a formal message when begun.

Another object of invention is the provision of a system offering great facility for switching portions of a central ofilce' apparatus from a general transmission system .and for including said apparatus in a local circuit for test and adiustment purposes.

Other features of invention are 'to provide/ mechanism for establishing code signals for indicating time, and to provide mechanism for producing a variable charging rate for a storage battery in accordance with the load placed upon the battery.

The noted objects are attained by a system of apparatusand circuits embodying amanual keyboard for setting up an omnigraphic formal message, a start-stop code-signal transmitter,

stepping switches for establishing time signal conditions and further stepping switches for connecting the keyboard to the code-signal transmitter for selecting keyboard members. ilxed signal members and time signal members, and

for selecting predeterminedly thereamong. A

start-stop telegraph set of any desired type may be used as a subordinate transmitter and home recorder at the central omce. At a substation, a

start-stop recorder without transmitter, and with motor, battery and battery charger are provided.

A more complete understanding of the invention may be obtained from the following description, taken in conjunction with the accompanying drawings, in which rectly below Fig. l with the correspondingly hum-- bered-eonductors matched to show the complete system;

Fig. 4 shows a circuit diagram of a substation; and

Fig. 5 shows a sample section of the tape printed, through the operation of the system.

In brief preview; the principalparts of the invention are as illustrated and identified by referenoe numerals in Figs. 1, 2, and 3.

Fig. 1 illustrates a set of apparatus constituting a transmitter for formal messages, and within rectangle 3i, Fig. 3, are symbolized a recording tape-printing receiver 32 and a code signal transmitter 33 which may be respectively, according to U. 8. Patent 1,745,633 to S. Morton et a1. and U. S. Patent 1,595,472 toKrum, which together with a motor 34 and a lamp 3!! form a complete recording and transmitting telegraph set. A duplicate set of apparatus for formal messages is provided, connected to conductors 38 while rectangle ll encloses a duplicate of apparatus shown in rectangle ,3l. Local repeating relays 40 and H are provided for repeating transmitted telegraph signals into local circuits and a plurality of duplicate line relays 42 are provided for repeating transmitted telegraph signals into line circuits.

A first transmission system of apparatus in the central ofllce includes the transmitter of Fig. 1 for transmitting formal messages, the telegraph set of rectangle 3!, Fig. 3, for home recording and for transmission of messages of unlimited content, a multi-pole switch 43 and the local repeating relay 40, all in association with control relays .44, 45, 48, a reversing relay 4! and transmitting line relays 42. A second or duplicate transmission system of apparatus in the central oflice, includes a duplicate of transmitter, Fig. 1, the telegraph set of rectangle 31, a multi-pole switch 4i, and a reversing relay 4!, all in association with repeating local relay comprise the local repeating relay 40, reversing relay 4! and switch 43 for test of apparatus of Fig. l and rectangle SI and alternatively the local repeating relay 4i-, reversing relay 49 and switch 48 for test of the duplicated apparatacts of manual keys 62 to a signaling circuit conductor 63, or through conductors 64 and contacts of other manual keys 65 to the conductor 63, or through conductors in cable 66, bank contacts and brushes of time-signal switches 61, conductor 68 and cam controlled contacts 69 to the conductor 63, while still further bank contacts of pilot switch 60 are connected directly and permanently to conductor 68 and through contacts 69 to the conductor 63. A start-stop distributor I2 which may be according to Patent 1,595,472 noted above, has its stop-signal contact connected to conductor 63 and has its code-signal contacts between brushes of pilot switch 66 and a signal circuit conductor I3. The distributor I2 is driven by a start-stop main shaft I4, there being a power action of armature of magnet 16 and arranged to be retained in. operated condition thereafter by a latch 'II controlled by a cam 18 on cam shaft 80 to make three pilot switch revolutions following each start in response to momentary operation of the starting magnet I6. Further cams on cam shaft 89 control other contacts of which the functions will be described in connection with description of circuits in which they severally are included. Main shaft I4 carries a cam 19 which once in each rotation engages a pawl 6i and operates the pawl to drive a ratchet 82 through 3 degrees of angle, thus driving the shaft'86.

Pilot switch 66 comprises a rotary stepping shaft 83 carrying six double-end brushes 86' and a ratchet 85 driven by a pawl 86 on armature 6'! of magnet 88. Three similar switches 9I, 92, 93, constitute a generator of time indicating code signals. In all such switches, bank levels are numbered I to 6, each bank having twenty-five contacts and a feed brush 99 for each doubleend brush is connected through a first terminal, as exemplified in switch 9i.

Five conductors 95 connect code contacts of transmitter 82 to the first contacts of levels I to 5 in pilot switch '69. In keybank 62, operation of any manual key will close the contacts illus trated adjacent thereto. Operation of any one of the manual keys 65 will connect the signaling circuit conductor 63' through selected conductors 66 to the fifth, sixth, seventh, eighth, ninth, tenth I and eleventh contacts in levels I to 5 selectively of pilot switch 60 for the purpose of setting up variant combinations of an electrical potential on the noted bank contacts. In like manner, operation of any thousands keys 96 will connect the signaling circuit conductor 63 through selected conductors M to the fourteenth contacts in levels I to 5 selectively, operation of any hundreds key 91 will connect conductor 63 to the fifteenth contacts in levels I to 5 selectively,

- clutch 15 to be operated to start by mechanical v bank contacts in pilot switch 66 as indicated in Fig. 1 while other indicated contacts in the first, second, twenty-secondand twenty-fifth switch positions are permanently connected to conductor 68 which is electrically connected to conductor 63 when cam controlled contact 69 is in closed condition.

In detail, operation of prefix key IIII connects conductor 63 through conductor I08 to the tenth contacts in levels I, 2 to form a code signal for A, and connects conductor 63 through conductor I09 to the eighth contacts in levels I, 4, 5 to form a code signal for B, and also connects conductor 63 through conductor I09 to the fourth contact in level 3 to change to "letters shift code signal (1, 2, 3, 4, 5) the code signal that is permanently connected to the fourth contacts in the other four levels for figures shift" (1, 2, 4, 5).

Operation of prefix key I02 connects conductor 63 through conductor I III to the sixth contacts in levels 3, 4, to form a code signal for N and key I92 also connects conductor 63 to conductor I98 to form code signals for B and letters shift as described.

Operation of prefix key I03 connects conductor 63 through conductors III, H2, H5 to the fifth, seventh and ninth contacts in levels I, 2, 5 to form a code signal for 2.

Operation of prefix key I06 connects conductor 63 through conductors I I I to the fifth, seventh and ninth contacts in level I to form a code signal for 3. Key I95'operates as described for key I64 but adds a connection from conductor 63 through conductor III to the eleventh contact of level I to form a code signal for 3.

Operation of prefixkey I06 connects conductor 63 through conductors H2, H4 to the fifth, seventh and ninth contacts in levels 2, 4 to form a code signal for 4. Key Iiii operates as described for key I66 but adds a connection from conductor 63 through conductor I I8 to the eleventh contact in levels 2. 6 to form a code signal for 4.

Thousands keys 96 each connect conductor 63 to the fourteenth contacts of levels I to 5 selectively to form that code signal indicated on the symbol of the key. Similarly, hundreds keys 9l connect conductor 63 to the fifteenth contacts selectively, tens keys 98 connect conductor 63 to the th contacts selectively, and units keys 99 connect conductor 63 to the seventeenth contacts selectively.

By permanent connections with conductor 63 there are set up in pilot switch 60 a code signal for double dash on the third and eighteenth contacts in levels I, 3, 4, a code signal for figures shift on the fourth and twelfth contacts in levels I, 2, 4, 5, a code signal for hyphen on thirteenth contacts of levels I, 2, and a code signal for space on the twentieth contact in level 3. When cam controlled contact 69 is in closed condition there are set up further in pilot switch 66 through con-E ductor 68' a marking condition on the first contact in level 3 to establish a space code signal on the first contacts in level 3,.a code signal for figure shift on the second. contacts in levels I, 2, 4, 5, a code signal for colon on the twenty-second contacts in levels 2, 3, 4, and a code signal operation of any tens key 98 will connect conductor 63 to the sixteenth contacts in levels I to 5 selectively, and operation of any units key 99 will connect conductor 63 to the seventeenth contacts in levels I to 5 selectively. Permanently connected to conductor 63 are certain of the third, fourth, tenth, twelfth, thirteenth and eighteenth for a time designating symbol AM on the twentyfifth contacts in levels 3, 4. I

The twenty-first, twenty-third and twentyfourth contactsin levels I to 5 of pilot switch 68 are connected to contacts of time code switches 9|, 92, 93, respectively, the brushes of those switches being connected to conductor 68. Connections thus are completedwhen cam controlled contact 69 is in closed condition by which there are set on the twenty-first contacts code signals representing the digital value of the instant hour under control of switch 9I, on the twenty-third contacts code signals representing digital value of the tens of minutes under control of switch 82 and on the twenty-fourth contacts code sig- -nals representing digital value of units of minutes under control of switch 93. On pilot switch twenty-fifth contacts the code signal is AM on levels 3, 4 when the conductor I20 which extends to the twenty-fifth contact of level 5 is held disconnected from conductor 68 by level 6 of switch 8I and the code signal is PM on levels 3, 4, 5 when conductor I is connected to conductor 68 by level 6 of switch 93 and when cam controlled contact 69 is in closed condition.

Starting circuit for clutch trip magnet 16 extends from ground I2I through lower contacts of manual locking preparatory switch I22, contacts of manual nonlocking starting switch I23 and clutch trip magnet 16 to battery.

' Stepping circuits for controlling movement of brushes of the pilot switch 60 are (a) from ground through stepping magnet 88, brush 84, contact I I in level 6, cam controlled contacts I24, parallel closed contacts I28 and contacts I25 of magnet 88, and local contacts I26 in transmitter 12 to battery, (17) from ground through magnet 88, brush84, level 6, and contact I26 to battery, (0) from ground through magnet 88, brush 84, any contact from 2| to 25 inclusive in level 6, conductor I21, closed cam-controlled contacts I28 and contacts I26 to battery, and (02) from ground through magnet 88, brush 84, any contact from 2I to 25 inclusive in level 8, conductor I21, contacts I25 (contacts I24 being now open) conductor I29 and contacts I 26 to battery.

Clock circuits for controlling movement of brushes of time-code switches 9|, 92, 93 are (for minutes) through battery, Fig. 3, clock contact I3I, conductor I30 and winding of stepping magnet I32 or minutes switch 93 to ground; (for tens oi. minuteshthrough battery, clock contact I3I, conductor I30, brush and tenth or twentieth contactin level 6 of switch 93, and stepping magnet I33 of switch 92 to ground; and (for hours) through battery, clock contact I3I conductor I30,

brush and tenth or twentieth contact in level 6 of switch 93, brush and sixth, twelfth, eighteenth or twenty-four contact in level 6 of switch 92 and stepping magnet I34 of switch 9| to ground. Automatic driving circuits for switches 9i, 92 and 93 are through battery, brush and twenty-fifth contact in level 5 of switch 9i, contacts I36 and magnet I34 of switch 9| to ground; through battery, brush and twenty-fifth contact of level 5 of switch92, contacts I31 and-magnet I33 to ground; and through battery, brush and any contact from the twenty-first to the twenty-fifth. inclusive, in level 5 of switch 93, contacts I38, I38 and magnet I32 to ground. A further time-switch control circuit extends through battery, cam-controlled contact I40, contacts I4I, I39 when operated b magnet I32, andwinding of magnet I32 to ground.

Keys 62 and 65 are looking manual keys and may be as shown in Fig. 2 where key member I42 operates contacts I43 and is locked in operated position by engagement of locking lug I45 with looking bail I44 common to all keys '62 and 65. Just before shaft 80 completes its cycle a cam I46 engages a follower I41 for operating bail I44 momentarily to unlock all keys.

and contact from 2 to 20 inclusive in For operation 01 the described apparatus, an operator closes the locking manual preparatory key I 22, Fig. l, which completes a local control circuit through ground I2I, Fig. 1 upper contacts of key I22, conductor I50 (Figs. 1 and 3), switch 43, conductor 'I5I, reversing relay 41 and battery, thus energizing and operating the relay 41. Prior to operation of relay 41, current had been flowing in a home recorder circuit from battery I52 through armature I53, resistor I54, conductor I55, switch 48, conductor I56, conductor I51, contacts of relay I58, conductor I59, home recorder magnet I80, motor control relay I8I, switch 48, conductor I62, switch 43, conductor I83, conductor I64, contacts of relay 45, conductor-I65, home recorder magnet 32, motor control relay 44, switch 43, conductor I66, resistor I61 and armature I68 toground I89. During the ensuing period in which relay 41 retains its operated condition, the described current in the home recorder circuit is reversed in direction, flowing from battery I52 through armature I68, thence through the loop circuit traced above and through armature I53 to ground I10. Reversal of current through polarrelays 44 and I6I operates those relays to close their contacts. Relay 44 closes a circuit through ground I2I, Fig. 1, lower contacts of switch I22, conductor I H, Fig. 3, contacts of relay 44, windings of relays 45, 4'8 and grounded battery. While motor control relay I6I is operated to close its contacts, the circuit of those contacts is not closed because of open condition of the preparatory switch corresponding to switch I22 in the duplicate transmitter. Operated condition of relay 45 removes a shunt path including conductor I64 and contacts of relay 45 from contacts of repeating relay 48 and the described loop circuit from battery I52 to ground I10 now includes conductors I12, I13, resistor I14 and contacts of relay 40 which accordingly control operation of the recorder magnet 32. Operated condition of relay 46 connects ground to conductor I15 which closes four circuits for signal lamp 35 and motor 34 of the set 3|, Fig. 3, also signal lamp I16 and motor I11 of Substation motors alsothe transmitter of Fig. I. have been started by operation of relay 41, as will be described in a description of the substation, Fig. 4.

The transmitter of Fig. 1 now is in conditionfor operation and the operator accordingly operates into locked condition one key only in each of th key sets 65, 96, 91, 98 and 99, then operates momentarily the starting switch I23, energizing the clutch trip magnet over a described circuit, thus permitting clutch 15- to engage its members to start the rotary transmitter 12. Presume that keys I05 and keysi in the sets 65, 96, 91, 98 and 99 have been operated. Transmission and mechanical operations will be as follows:

In its first. revolution, transmitter 12 transmits space code signal through conductor 68 and contacts 89 from the first contacts in pilot switch 60. Meanwhile, cam 19 operates pawl 8I and shaft 82 one step, whereby cam 18 rotates into its interfering condition to restrain the latch 11 from disconnecting the clutch 15, cam I closes contacts I24, cam I 8I closes contacts I48, I82, and cam I83 closes two pairs of contacts I84. Cam I as yet isv ineffective. Contacts I24 prepare a circuit for stepping the pilot switch 80. Contacts I40 prepare a circuit for control of time switches M, 92, 93. Contacts I82 form a shunt around contacts of subordinate transmitter 33, thereby rendering the subordithe several revolutions. dition of contacts 59, H occurs before brushes t2 and 8t and by by setting of one key in each nate transmitter ineffective. Upper contact of pair I82 is connected over conductor I3 to righthand ,terminal'of transmitter 33, while lower contact of pair I82 is connected over conductors I86, I81 to left-hand terminal of transmitter 33, thus shunting the subordinate transmitter 33 when the chief transmitter of Fig. 1 is operating and is holding contacts I82 closed. Contacts I88 are connectedin parallel with contacts of preparatory switch I22 and render all apparatus continuously' operative independently of said key while the chief transmitter is operating. The pilot switch 56 makes three revolutions in response to one operation of clutch magnet It. Contacts 69 and ifid open at a, mean moment in the first revolution of switch 6d and close at a mean moment in the third revolution of switch dd, thereby rendering transmission variant for The first change in conof switch dd have engaged the twenty-first contacts in the first revolution and the second change occurs beiore the. brushes have engaged the twenty-first contacts in the third revolution.

Transmitter 12 has six pairs of contacts, each pmr controlled by an individual cam on shaft l6. Contact I29 closes and opens while the contact "connected to conductor d8 is closed. Contacts connected to conductors 88 and d5 operate in timed relation to transmit Baudot code startstop signals. Each of the contacts in transmitter 52 connected to conductors at closes in every revolution of shaft 7 3, thusconnecting the signal circuit'conductor it through to conductors d5 serially in order for transmission of: each-code signal. The transmission conditions of max-Eng or spacing for each impulse of the code signal are determined by the connective condition between brushes of switch 6% and signal circuit conductor 63 and these are predetermined by permanent wiring, by operated contacts in keys brushes in switches 9t, 92, 98.. Just before the termination of th first revolution of shaft id, after starting by magnet I6 as described, contacts E25 open the described "stepping circuit (a) previously closed at any instant during the revolution. Pilot switch brushes are advanced from the first contacts to the second contacts during the stop" interval of transmission. Clutch latch I1 is in restrained condition by cam It, clutch "remains engaged and rotation of shaft It continues.

In its second revolution, transmitter 12 transmits figures shift code through conductor 6% and contacts 69, and contact I28 closes stepping circult (2)) to advance the pilot switch brushes from the second contacts to the third contacts.

In its third, fourth, twelfth, thirteenth, eighteenth and twentieth revolutions, transmitter. I2,

, transmits, respectively, code signals for double dash, figures shift second occurrence), figures shift (third occurrence), hyphen, double dash (second occurrence) and space, invariably, by permanent wiring of signaling conductor 68 directly to pilot switch contacts. In fifth to eleventh revolutions of transmitter 12, the transmission is determined by setting of a key in key set 65, and in fourteenth to seventeenth revolutions of key sets 93, 91,

In each revolution-of main shaft I8, the cam shaft 30 has been advanced one step by action of com I3, pawl BI and ratchet fl. when pilot brushes reach contacts 2|, cam I85 has operated its contacts 58 and I23 into open condition, and

there is no connection for transmission from the twenty-first to twenty-fifth contacts. From the second contacts to the twentieth contacts in the pilot switches, thebrushes have been advanced by stepping circuit (b). With brushes in engagement with the twenty-first to twenty-fifth contacts, the contact I26 closes stepping circuit (02) and magnet 88 operates in vibrating mannor by reason of its contacts I25. Brushes of the pilot switch pass quickly from the twentieth contacts to the first contacts when contacts I28 are open in first and second cycles of operation of pilot switch Gil. Transmission in first pilot cycle has been =33335555=. 1

For second cycle of pilot switch fill, transmission from transmitter I2 is blank code signal with brushes on the first and second contacts because conductor 68 is disconnected at cam -controlled contacts 69, the cycl thereafter being completed as in first cycle from the thirdto the twentyfifth contacts inclusive, with repetition of transmission noted above.

For third cycle of pilot switch 60, operation is as described for second cycle from the first confacts to the twentieth contacts inclusive, during which time cam I85 has closed contacts 69, E28 and cam I80 has opened contact IZ i. Transmission from the third to the twentieth contacts inclusive, has been as noted above in first pilot cycle and conductor 68 being now connected to conductor 63 at contacts 59, transmission continues through the twenty-first pilot contacts and time switch ill to conductor 68, for a code signal representative of the hour, the hours Ill, II, I2 being logotypes transmitted by a single code signal,

then through the twenty-second pilot contacts permanently connected to conductor 68 for a code signal for colon,- then through the twenty-third pilot contacts and time switch 92 to conductor 68 for a code signal representative of the tens digit of minutes, then through the twenty-fourth pilot contacts and time switch 93 to conductor 68 for a code signal representative of the unit digit of minutes, then through the twenty-fifth pilot contacts of levels 3, t directly to conductor 68 for a thus efiecting; for example, transmission of code gization of stepp signals for 12:32 PM.

Thus, a master control shaft 80 and cams have controlled the rotary pilot switch 60 to select among settable keys 62 and 65, and time register Bl variantLv in successive revolutions.

Brushes oipilot switch 60 now are advanced by circuit (0) into normal position, engaging the first contacts, the No. -1 contact in level 6 being connected to cam-controlled contacts I2t now open so that a circuit cannot be closed for enermagnet 88. Shaft It has made revolutions, ratchet wheel 82 of 120 teeth has made 75 steps. Shaft It makes 35 more revolutions, transmitting space code signal 35 times through pilot brushes on the first contacts and advancing shaft into normal position where cam I8 releases latch ll, which opens clutch I5 at end of next revolution and stops shaft I4.

The total described transmission comprises message,

representing code signals 12:32 PM of which all digits other-than time are controlled by keys 62, 65 now restored by cam I46. Should starting switch I23 be operated without setting any key 62, 65, then a message will be transmitted to print only the permanent or nonsettable codes followed by the time codes, thus, 12:32 PM.

A local signaling circuit extends through baittery 200, Fig. 3, switch 43, conductors 20I, I81, subordinate transmitter 33, conductor 13, Fig. 1, chief transmitter I2, conductor 63, Fig, 3, operating winding of local repeating relay 40, conductor 202, switch 43, conductor 203, switch 48, conductors 204, 205, subordinate transmitter 206, conductor I3, duplicated chief transmitter (as I2 not shown), conductor 63', local repeating relays 4|, conductor 2H1, switch 43, conductor M I, and through operating windings of all line repeating relays 42 to ground. In response to control by a transmitter, all repeating relays 40, 4!, 42 operate their armature contacts. Normally all transmitters and recorders are inoperative because no motor is running. Contacts of local repeating relays are shunted by contact of relays 45 and I58.

Central oflfice testing conditions are set up by reversal of switch 43 for test of set 3|, Fig. 3, and

the local control circuit reformed through battery 152, armature I53, resistor I54, conductor I55,

switch 48, conductors I56, I51, contacts of relay 158, conductor I59, recorder magnet I60, relay iel, switch 48, conductor I62, reversed switch 43, conductor I56, resistor E61 and armature I68 to ground I59. The local signaling circuit is reformed through battery 200, reversed switch 43, to conductor 233 and thence a described above, eliminating set 3! and the chief transmitter of Fig. 1 from the local signaling circuit. -The described control circuit including conductor 150 is changed in reversed switch 43 from reversing relay 41 to reversing test relay 43. Operating winding of local repeating relay 4i is switched into a local test transmission circuit through battery 255, reversed switch 43, conductors 231i I87, transmitter 33, conductor I3, transmitter l2, conductor 33, operating winding of relay 43, conductor 202, and reversed switch 43 to ground. A home recorder test circuit is formed through battery 2I6, armature 2II, conductor 2I8, reversed switch 43, relay 44, recorder magnet 32, conductor 565, contact of relay 45, conductors I64, I53, reversed switch 43, and armature 2I9 to ground. A lamp 220 signals that the set is on test conditions when motors are stanted. Operations and functions of the described test circuits are obvious in light of description above of operation of WOIkiIlg signaling circuits. A plurality of line circuits, as 52, 53, are served by battery I52 and armatures I53, I68 as a source of current supply, and code signaling is effected in each circuit by contacts of line repeating relay 42. When reversing relay 41 is operated to start the central station motors as has been described, current is reversed in all lines 52, 53 to start substation motors, as will be described. Each line circuit serves a plurality of substation. equipments 5 I, one of which is illustrated in detail in Fig. 4.

Line circuit of the substation is from line conductor 52 through motor control relay 230 and recorder magnet 23I to line conductor 53. A test switch 232 when in normal position closes a circuit from relay 230 to motor relay 233, the contact of which, when operated, closes three circuits, for a motor 234, for a signal lamp 235, and for winding switch 231, when operated, shunts the contacts of relay 236. Alternating power current from supply mains 240 energizes a signal lamp 241 and through a transformer 242 provides current for an alarm bell 243 controlled by contacts of low-voltage detector relay 244, connected to storage battery 245, through a ballast resistor 24B. Means for chargin the battery 245 comprises an auto-transformer 241 having a primary connected to power source 240 and having asecondary connected through space-discharge rectifier 248, a ballast resistor 249, a trickle-charge ammeter 258, a choke coil 25I, and the storage battery 245.

For operation, manual switch I22, Fig. l, and subsequently cam contacts I84 are closed to energize and operate reversing relay 4! which reverses direction of current flow in line conductors 52, 53. Reversal of current in the line circuit, Fig. 4, causes relay 230 to reverse is contactual condition, energizing relay 233 which starts motor 234 and energizes relay 236. Code signals in the line circuit are of neutral or make and break nature and effect recording. A mechanical bias in relay 230 holds the contacts closed during break intervals in the signaling line current. Contacts 0f operated relay 235 shunt the ammeter 250 and choke coil 25I, increasing the battery charging rate to a rate approximating the current consumption of motor 234. Battery 245 may be discharged by open condition of switch 252 and may be recharged at high rate when motor 234 is not running by closed condition of manual switch 231.

To remove the substation set from line control for purpose of test, manual switch 232 is reversed, placing motor relay 233 under control of manual key 253, connecting a signal lamp 25 to indicate that the substation telegraph set is not controlled by the line current, and reversing connections of alarm device 255. When switch 232 is normal, as shown, during receipt of a message, the device 255 will be operated by current through contacts of relay 233. When switch 232 is reversed for purpose of test, device 255 will be operated by current through contacts of relay 230 while no message is being received.

The invention, having been described in connection with an illustration of a specific embodiment thereof, will be definitely pointed out in the appended claims without limitation to-the specific illustration utilized herein.

What is claimed is:

1. In a telegraph system, two'home recorders, two signal-repeating relays having contacts associated with said tworecorders, shunts for the recording contacts of said signal-repeating relays ing of a high-charge relay 233. A manual lockrespectively, motors for said home recorders respectively, and common means for starting one of said motors and for removing one of said shunts to qualify one of said recorders for operation in response to one of said signal-repeating relays.

2. In a telegraph system, two home recorders, two signal-repeating relays having contacts associated with said two recorders, shunts for the contacts of said signal-repeating relays respectively, motors for said home recorders respectively, shunt-controlling relays for, said shunts, motor-starting relays for said motors, a transmitter connected to supply signals to said signalrepeating line relays, and a circuit through one of said shunt-controlling relays and through one of said motor-starting relays and controlled by said transmitter for starting one of said motors and for opening one of said shunts to qualify one cam-controlled contacts in said transmitter for:

controlling said reversing relay for retaining said motors operative independently of said manual key while said transmitter is operating;

4. In a signal transmission system, duplicate transmitting apparatus for alternative service with a common communication channel comprising two supervisory cam shafts, two sets of pilot switches operatively and respectively associated with said cam shafts, means associated with each of said transmitting apparatuses for initiating one of said cam shafts and its associated pilot switch into operation, and interrupting means for preventing the effectiveness of either of said initiating means during the period of operation of the other of said associated cam shafts. In a signal transmission system, a broadcasting circuit, a local test circuit, a pair of keyboard transmitting and recording units, apparatus for optionally associating either one of said units with said broadcast circuit exclusively of the other of said units, a pair of repeating relays each associated with oneof said units for pro ducing signals over said local test circuit, and means under the control of each of said units for shunting the effectiveness of the repeating relay associated with the other of said units for thereby mutually excluding the other of said units when one has been seized and operated. 6. In a signal transmission system, two series of signal generating elements comprising in each series an identification signal keyboard transmitter, a time signal transmitter and a printertransmitter unit, a, cyclically operative timing shaft including means for allocating a predetermined interval of transmission for associating with a line cyclically each said identification signal keyboard transmitter and said time signal transmitter, and means subordinated to said timing shaft for permitting. said units to be associated with said line when said identification signal and time signal transmitters have .com-

principal and secondary timing shafts, transmitter apparatus cyclically associated with a transmission channel under the control of said secondary timing shaft, and means operative by said principal timing shaft to modify said transmitter association with said secondary timing shaft once for a predetermined plurality of saidassociations.

8. In an alarm system, a keyboard coding apparatus comprising a set of decimal integer key elements for each of a series of decimal name-- with each of said recorders having transmitting contact armatures, means for normally shunting electrically the transmitting contacts of said relays, motors for actuating said recorders respectively, a starting key associated with each one of said recorders, and a, reversing relay common to both ofsaid recorders mutually operative to start the motor associated with its particular recorder and remove the shunt from its associated repeating relay for thereby preparing its said associated apparatus for transmission.

10. In a system for broadcasting signals over a loop circuit, a pair of alternatively operable home recorder-transmitter units, each equipped with a printing mechanism for making a home record of matter transmitted over said loop and a keyboard mechanism for generating miscellaneous matter transmission signals, a time signal transmitting apparatus, a keyboard identification code transmitting apparatus, and a pilot switch comprising a rotary member having a plurality of contact levels each associated with a signal component of a permutation code and a number of contact positions in the operative cycle of said pilot switch corresponding to a number of signals predeterminedly associated with said keyboard coding apparatus, said time signal generating apparatus, and said home recorder-transmitter apparatus.

11 In a'telegraph broadcast system, a transmitting station apparatus comprising duplicate keyboard transmitter equipments each having a home recording printer, a control circuit including a pair of repeating relays respectively associated with said transmitters, a start key associated with each of said transmitters and with a common circuit, and means associated with each one of said start keys for disabiing the other of said start keys from control during the in terim of its own operation.-

12. In a telegraph transmission system comprising a pair of alternative transmitters, a motor associated with each one of said transmitters, an energizing circuit for each'cf said motors, and means for selecting for operation one or the other of said alternative transmitters un der the control of its motor energizing circuit comprising a pair of polar relays and a reversing switch for normally maintaining the-current flow through said relays in one direction and re sponsive to an individual key. associated with each one of said transmitters for reversing the direction of current flow through said relays, and a pair of manual keys, one for each transmitter for supervising the eifectiveness of its saidtransmitter by completing its motor circuit.

JAMES E. WACK. WALTER J. ZENNm.

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