US1638330A - Selective signaling system - Google Patents

Description

1927 G. w. FLYNN SELECTIVE S I GNALING SYSTEM I Filed March 2. 1921 4 C m m mmr WEE-.

Patented Aug. 9, 1927.

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GEORGE WILLIAM FLYNN, OF BLUNDELLSANDS, NEAR LIVERPOOL, ENGLAND.

SELECTIVE SIGNALING SYSTEM.

7 Application filed March 2, 1921, Serial No. 449,103, and in Great Britain July 4, 1919.

(GRANTED UNDER THE, PROVISIONS 01? THE ACT OF MARCH 3, 1921, 41 STAT. L, 1313.)

The present invention relates to electric signaling systems such as are used for selectively signaling one or more stations connected to a common line or so called omni bus circuit. Y

A considerable diificulty has been experienced hitherto in selecting stations where the number of these connected to one lineis large, say in the neighborhood or 100, and consequently the equipment installed, has been proved to be either'unduly expensive on account of the intricate nature of the apparatus or has failed to give satisfactory and reliable results under the exceptionally adverse conditions of working to which such systems are subjected.

The object of the. present invention is to provide simplified apparatus at each out-station and at the control station which will be reliable and satisfactory and at the same time will enable the number of stations to be increased up to say, a hundred, without any ad ditional features in the substation apparatus.

According to the invention, the out-stations are selected by means of a number of independent series of impulses which may be produced by the, agency of a dial-switch of identical construction with those used in automatic telephone systems, operated at the signaling or control station. The out-stations are provided with a selective device such as a rotary or like switch in which a driving magnet causes a wiper to successively pass over and make contact with a series or bank of contacts. Each out-station is identical except for simple connections to certain contacts which connections are pe culiar to the station, and also other similar connections peculiar to eithera group or to the whole of the stations if it is desired to ring up either a particular group or twhole of the stations at once.

Each station will be numbered, usually in the decimal notation, to correspond to the ten impulses sent by the well knowndial switch. Then, if there are not more than a hundred stations which will usually be the case, only two digits would be dialled. The dialling of the tens digit would cause the switches at every station to operate, but in digit.

only ten cases would the wiper rest on a contact which was connected up so as to prepare a circuit in order that the bell to be selected may be rung on the dialling of the units This next dialling then eitects a second operation at each of these ten stations and preferably the further operation ofthe switches already operated. This next dial ling moves ,the wiper to another contact which only in the case of the station required, will be connected up to complete the operation and effect the ringing of the bell.

Arrangements are provided for enabling the out-station to ring up the. control station, also a means is incorporated of letting the control station know when the bell at the out-station selected is ringing in response to the operation of dialling.

Further details of the invention will be better understood by referring to the accompanying drawings which illustrate one meth 0d of carrying out the invention by way of example. Fig. 1 shows diagrammatically the'c0nn6ctions' of the apparatus at the control station and the out stations, Fig. 2 shows diagrammatically one form of dial switch employed.

The apparatus at station C which is the. calling or control station, is provided with a speaking or ringing key 1, through which the operators instruments are connected to the line A B. An impulse relay 5 is adapted to be connected through the springs 6 and 7 of key 1 with the circuit battery 150, a dial switch or calling device 3 of the type usually used on automatic telephones being connected with itscontact springs 3 and 3 in series with the relay 5 and battery 150. The construction of the dial switch 3 is more particularly shown in Fig. 2. The relay 5 functions to reverse the polarity of the battery 4 on each interruption of the current passing through the relay5 by the dial switch 3. To prevent the outgoing impulses being overheard by the operator the dial' switch 3 is provided with an auxiliary pair of springs 59 arranged to short circuit the winding 57 of induction coil 58 when the dial is ofi' normal due to the sending of the impulses. I

The speaking sine of the key 1 is connected to the line A B through spring 8, wire 71, spring 72 and also through spring 19, spr' m 79, wire 79 and spring 78. The speaking set comprises receiver 76. induction coil 58 having windings 57, 74. 75 and 8 1, transter 85, cut out switch. S3, and inductive resistance 86.

A hell 9? and line ianip 95 are connected lso to the line A when the springs oi the speaking side are in normal position, by the following arrangement Springs 89. 91 of key 1, sensitive line relay 90. which latter operates to complete the circuitof relay 92 through earth. battery, springs 81 and 9;: ct key 1, contact lamp 955. relay to earth and also associated circuit 01" hell 9?.

At each out sta on D. F, a. polarized relay is connected across the line A B through normally closed springs 21, 22 02" key 20", noninductive resistance 23. winding 2 1- of relay 20. springs 25. 26 of key 20 to line The relay 20 operates to close one of two circuits through contacts 28 29 or 28. 82. The former closes the circuit of a slow acting relay 2? and the contacts 28, 32, when this latter circuit is closed close the circuit of a rotary selective switch 38 through a stepping magnet 36 and holding relay in parallel.

The rotary switch 38 comprises a number or": contacts in this c twentybne in ninnber, such as 37 forining the arc of a circle, a contact are 4.0, wiper 39 adapted to contact with the individual contacts of the are 10. The wiper is stepped around by the inipulses passing through. the electro-n'iagnet 36 which operiiites suitable stepping mechanism such teeth mounted on a circular plate connected with the wiper 39. Mounted on the said plate a projection 110 opted to separate pair oi" contact springs 48 when the wiper is zero position. A release magnet 69 opei .ting detent holding the toothed plate ot the wiper arm 39 also provided and operates as hereinafter descr bed. Associated with the rotary si itch is a bus l or device 111 con'iprisiug a sin'iih r number of terminals such as 12, 52. 101. as provided on the switch 38. a tens bar and u bar Each at t e contacts of the rotary switch 38 is connected to the correspc .ding terminal ot the device 111. or at least seine will be later denuinher of the connected to 111 correspond ing to t teps digit and Llle tens bar is! the efore lies adjacent the first ten terminals onl The units bar 53 is connected to that terminal of the device 111 which corresponds to the sum of the tens u s digits the outstation. F or example if the number of the station is the tens car at is connected a pivoted pawl. engaging with stations have terminals and 9 connected by a link, if desired as also terminal and 102. Associated with the tens bar 4% is a circuit including contact d5 of holding relay 35, relay ll" and earth. Connected with the units bar 53 is a circuit comprising contact of relay a l, contact 46 of relay 35;. bell 55, winding 56 of relay 20 and earth. I

A speaking set including receiver and transmitter 65- is connected across the line A B through a switch having a plurality of springs 63, 6d, 66, 67; 68 tl a. function of which will be hereinafter described A conde; ser 61 and induction coil 62 are inserted in the circuit as shown.

It it is desired to call up the operator at station C from the outstations D, E, F, etc, the operation of the calling key 21) connects a ringing battery from earth through springs 88, to line A, through operation indicati devices. line B, springs 26, and 87 of key 2 to the earth. 7

Fig- 2 shows asuitable form of dial switch or calling device. This comprises a finger plate llo'having perforations 116 and rotatably mounted ona central spindle 119. Below thcplate is a. further fixed number plate having numbers 118 thereon from 19 and O. Pivotally mounted on the plate 115 is a pawl 121 adapted to engage the teeth of a ratchet wheel 120 capable of rotational increment about the spindle 119. Rigidly secured to the ratchet 120 is a cam wheel provi led with a plurality of teeth or projections corresponding to the numbers mounted on the number'plate.

The dial switch is provided with a pair of interrupter contact springs 3 and3 and also a pair of oil norinal contact springs 59 the longer one of which engages with an insulated pin 12% adapted to hold the springs outof contact in the normal position. A linger stop 12% is rigidly secured to the back plate 117.

To dial a number or digit the finger is inserted in the opening 116 of the finger plate 115 through which the required number on he number plate 11? can be seen and the slate 113 is rotated in a clockwise direction until the finger abuts against the stop 12 i. lly this action the pawl 121 carried over fi litllllbtli of teeth of the ratchet wheel 120 corresponding to the number select d and tens ons. spiral or the lilre springs, (not shown) usually assembled about the spindle 119.. 9n the releasing of the linger plate 115 the spring returns the plate to its normal position and in consequence. the movement the pawl 121 rotates the ratchet wheel 120 and therewith the cam wheel spring 3" and to cause the same to break contact with the spring 3 according to the number dialed.

When the plate 115 is moved from its nor mal position the pin 123 being removed from the longer of the off normal contact springs 59 allows contact to be made between the two which remain in contact all the time the plate, 115 isaway from its normal position;

To ensure uniformity in the interrupt-ions.

of'contact springs 3"and 3" a suitable goveining device may be incorporated in the mechanism of the switch thereby controlling the return movement of the plate 115.

Referring to Figure 1 the-operators set includes a speaking and dialling key 1, a speaking set 2, a dial switch 3 which may be of the well known type as used in automatic 13 of relay to positive pole of battery and thence from negative pole of battery through contacts 14 and 15 of relay 5, inductances 16 and 17, contact springs 18 and 19 of key 1 to 15 line. i

it each out-station the efiect of connecting batt ry 4 to line is to operate the polar. ized relay 20 of that station through the following circuit from positive pole of battery connected to line A through springs 21 and ofcalling key 20, through a non-inductive resistance 23, winding 24 of-relay 20, through springs 25and 26 of calling key 20 to negative pole of battery connected to 13 line. The polarized relay 20 operates in such a manner as to close the circuit of the slow releasing relay 27 through its contacts 28 and 29. The operator at the control station then works the dial to send impulses to line in accordance with the number of the .wanted party. Assume that the party wanted is number 53. He null then dial 5 breaking the circuit of impulse relay 5 times.

The impulse relay allows-its armatures tofall back and reverse the polarity of battery connected to line. aswill be seen from tracing the circuits, line A instead"ofbeingeonnected to positive pole of battery 4 through springs 12 and 13 will be connected to negative pole of ba tery through springs 12 and- 30 and line B will similarly be connected to positive pole of battery through springs 15 and 31. p

The effect of these momentaryrev'ersals of current'i's to cause all the polarized relays 20 connected across the line to operate so to call a party .ner of the figure.

that the contact member 28 momentarily) makes contact with contact 32. The first impulse closes a circuit as follows: earth. contact 28 and 32 of relay 20, contacts 33 and 34 of relay 27, which being slow acting will not fall back formomentary breaks in its circuit, slow acting holding relay 35 and driving magnet 36 'inparallel, to normal' contact 37 of rctaryswitch 38,- wiper 39, are 40 to cart-lied battery 1401 Thedriving magnet operates to step the wiper 39 one step, which'breaks the battery connection through contact '37, afurther connection to battery 141 being made by means of theen tactsprings 41 of relay 35-which'being of the'slow release type remains operated during the subsequent impulses of the same series. fore due to the-contacts '28 and 32 making and breaking so-many times 'cause'the driving magnet to'stp t'hewi er 39 to the fifth contact 42 from normal. Thej efi'ect of this is to connect positive pole of battery 140 to the fifth. terminal 42in the row of 21 terminals shown at the lower right hand cor- The 20 contacts of r the rotary switch are connected to these 21 terminals by conductors as shown diagrammatically in the drawings, the twenty-first terminal andtenth terminal being connected together for reasons to be explained later.

Atall stations whose numbers have 5 for the first digit a wire link is provided connecting the fifth terminal to a bus bar 44 termed a tens bar which is placed adja: cent to the first ten terminals as shown.

Now after the first five impulses have been sent there is a slight interval which permits the relay 35 to de-energize, allowing the contacts45 and 46 to close and contact 41 to open.

The result of this is that the following circuit is closed in the ten stations whose first digit commences with 5, but not in any of the other stations: battery 140, are 40, fifth contact 42?, fifth terminal 42, tens bar 44, contacts 45 of relay 35, relay 47 to earth. A circuit had previously been closed through relay 47 from battery 148, off normal springs 48 (now closed) of rotary switch resistance 49, relay 47 to earth, but

the current through this circuit while sufiicientto maintain the relay 47 operated is insufficient to operate it by itself due to the resistanee49; consequently the relay 47 is o'perated-through-the first mentioned circuit and is subsequently maintained oper-. ated'through the second circuit.

Theoperator" then proceeds to dial the units digit-3. the effect of the" first impulse'is' to send an impulse of current through the following circuit: earth, contacts 28 and 32 of polarized relay 20, contacts 33 and 34 of relay 27, relay 35' and driving magnet 36 in parallel, coiiifect'i'oh'po'iii't 1-42, Contact 50 and The remaining four impulses there wire link on the fifth terminal which is only v present in such stations The holding relay 35 operates as before connecting battery 1 11 through contact 41 for the subsequent operation of the driving magnet lieu of that supplied through the fifth contact and wire link which is removed on the advance of the wiper 39. The driving magnet operates to step the wiper to the sixth contact and with the two subsequent impulses steps it to the eighth contact 52 when the dialling being completed the holding relay 35 is deenergized. At station numbered 53 there will be a second connecting link joining the eighth terminal 52 to a second bus bar 53 placed adjacent the second to nineteenth terminals and termed the units bar.

Consequently when the wiper rests on the eighth contact sufficiently long for the relay 35 to be (ls-energized a circuit will be closed as follows: battery 140, are 40, wiper 39, eighth contact 52, eighth terminal 52, wire link to units bar 53, thence through contact 0t relay 47, contact 46 of relay 35, bell through a few turns 56 on polarized re lay to earth. The bell rings and at the time by means of the winding 56 on polarized relay 20, a current is induced on.

I ductance 10 in series with the impulse circuit.

In order to avoid the outgoing impulses being overheard by the operator the dial switch 3 is provided with an auxiliary pair of springs 59 arranged to short circuit the winding 57 of induction coil 58 when the dial is oil normal due to impulses being sent. 7

The called party at station No. 53 hearing his bell ring, lifts his receiver 60 to connect his speaking set in circuit, the receiver 60, being connected across the line in series with the condenser 61 and secondary winding of induction coil 62 by means of the switch hook springs 63 and 64 while the transmitter 65 is connected to battery 165 through the primary of induction coil 62 and switch springs 66 and 67. A circuit is momentarily closed on lifting the receiver. from battery 165, switch springs 67 66 and 68 and release magnet 69 to earth. The release magnet operates to remove detent 70 from ratchet wheel of rotary switch which rseasso in'nnediately restores to normal; the OE normal springs 48 then break contact and relay l7 de-energizes. At the same time the bell circuit is broken. I V p The operator then noticing the cessation of the ringing tone places his key 1 to the speaking position (i. e. to the left) connecting speaking set across the line over the following circuit: line A, springs 8 and 71, 72 and 73 of key 1, winding 74: of induction coil 58, winding 75 and receiver 76 in parallel springs 77, 78. 79 and 19 of key 1 The removal of current from the line causes the polarized relays 20 at every sta- 7 tion on the line to restore to their normal position with the contact'QS midway between contacts 29 and 32 and making contact with neither. The result is that the relay 27 die-energizes. Consequently the following circuit is closed at contact 80, battery 1418, of? normal springs 48, contact 80, release magnet 69 to earth. It will be understood that this occurs at every station on the line, exceptthe selected station, as every rotary switch has moved either to the rfith or the eighth contact and therefore the oil normal springs 48 are closed;

Jpon the rotary switches v38 returning to normal, the off normal springs 48 break con tact, breaking the circuit of the release magnet and also the circuit of the relay 47, so that every station is restored to normal,

When the conversation is finished the called party restores his receiver to the switch hook and the operator places his key in the normal position. it will be appreciated that in order to ring any out-station hell it is necessary to operate the relay 17 which depends upon the tens digit and subsequent-- .lv to operate the bell which depends upon the units digit, and upon the operation of relay 4?. For instance, in the case of station 62, his rotary switch will remain on the fifth contact, and will not be further oper ated, so that although the same total number 0t digits are dialled, as in the typical example 53) an entirely different result en sues. Similarly it will be appreciated that only one of a hundred stations will be rung up it the cross-connecting links at each station are arranged correctly, for instance number 11 will be connected with 1st terminal connected to tens bar and 2nd termition to earth, The line relay is designed to respond to nal to units bar, number 16 with lstterminal .to. tens bar. and 7th'terminal to units bar,

number 43 with 4Eth terminal totens bar and 7th (4+3) terminal to units or generally number at with a teri'ninal to tens bar and a'H/ terminal to units bar.

ator, this may be done by pressing the call ing key 20 which connects battery across the line through the circuit battery, springs 88 and 21 of calling key 20 to line A, thence to springs 8, 71, 72, 89 of key 1, sensitive line relay 90, springs 91, 78, 79 and 19 of keyl to line ,B and thence through springs 26 and 87 of calling keyi20 of calling stathis current, while the polarized relays 20 are preferably arranged as to be incapable of responding. Relay 90 operatesand closes the circuit of relay 92 which locks itself over the circuit-earth, relay 92 and itsc ontact 93,

springs 94 and 81 of key 1 to, battery at the same time the line lamp. 95 illuminating in series with the night alarm relay 96 which is adapted to close the circuit of the night bell 97. As soon as the control station operator operates his key to the speaking position the locking circuit of relay .92 is broken and the lamp95 is extinguished. In certain cases it is oftendesirable for the controller to COIHHIUIIlCEItQWltll alllthe out-stations at once or to communicate with all the stations of a given group "and this may readily be ellectedby the following 'arrangement.

It'will be assumed first of all that the controller desires to communicate 'with all the stations at once, in order to efiect this the twentieth terminal 98 of each stationis'connected by a crossconnecting link to'an auxiliary terminal 99 adjacent with the. units bar; also the twenty-first terminal 100 is 7 wired tothe tenth terminal lOl perinanently as shown while a cross connecting link con- 'nects it to a second auxiliary terminal lQ2.

In order to call all the stations the controller dialsO O (Ov signifying ten impulses).

The dialling for the tensidigit issiinilar to that previously describedythe *rotary switchesall being rought with their wipers 39 on the tenth contact-.froin normal.

tens bar. the subsequent diallingcauses-the instruments to operate as p'rcVi usly de- 4" scribed with reference to the-calling of stathose stations atwhich thereis across con necting link from the tenth terminal to the v ployed a reversal of current operating a anddi'iving magnet 36 in parallel, contact 50 and 103 of relay l7, terminal 102, cross connecting link to terminal 100, thence to tenth contact of rotary switch, wiper 39, arc 40, to battery. Relay 35 operates and remains operated through the subsequent series of impulses to hold contacts .41 closed so that driving magnet 36 continues torespond to the impulses at every station, consequently on the tenth impulse of the units digit the wiper 39' comes to rest upon the twentieth contact, the following circuit being closed:

ear th, battery, are 40, wiper 39, twentieth cont-act to terminal 98, cross connecting link to terminal 99, contact an of relay 35, bell 55, winding 56 of relay 20 to earth. As itis only necessary for the twentieth contact to be reached, the bells at every station will ring. I

It will be appreciated that by ieglecting to provide cross connecting links between terminals 98 and 9,9' or 100 and 102 at any stations these stations may be made exceptions to the general rule.

I Similarly other group calls may be arranged by suitably connecting certainolf the roup of terminals with the tens and units bars, in addition to the connections appropriate to the individual numbers of the respective instruments,

and in this way groups of stations may be rung at a time.

, For instance itmay be decided that the number 53 instead of being the number of a station is the number of a group cal Then all stations belonginglto that group will have connecting links from the fifth terminal to the tens bar and from the eighth terminal to the units bar preferably the members of thegroup will all have 5 for theirjfirst digit, this will avo d unnecessary complications.

I It w llbe appreciated that a very (ZlllClGDt select ve signaling system capable of dealiiig witha largenumber of stations has been evolved, at the same time it must be understood that the invention is by no means limited to the construction described as several modificatio s may be made therein without departing I V rinongotber modifications it will be ap- PlQClttlZQCldhtll? it is by no means essential that the impulses should consist of reversals of'current. The reason'for employing reversals instead of'a'direct make and break s to increase the reliab lityoi": the system, itbeing well known that for longlines on which the invention will usually be em polarized relay is more .efi'ective than a simple make or break. Furtherpthe arrangeoiu. the spirit of the invention. Y

ment of inductances 10, 11, 16 and 17 with the condensers 104: and 105 in shunt as shown in the drawings is not essential but is desirable for the eiiicient transmission of the impulses over a long line.

Also, it must be understood that the arrangement of batteries shown is only conventional and it is by no means essential that there should be an earth connection at either the out station or the controllers station as regards the battery. Further there will usually be only one or at most two batteries at each out-station, one for the transmitter circuit and one for the driving magnet and the operating relays.

I declare that what I claim is 2- 1 1. in a selective signaling system the com: bination oi a central station, a plurality of outlyiin stations each having a designation number, a common line connecting said stations, means at'said central station to transmit over said line a plurality of series of impulses, an indicating device at each of said outlying stations, a rotary selective switch at each at said outlying stations having a single rotary arm. and a plurality of contacts, means to drive said arm in response to the first series of impulses received from said central station, an electrical. circuit at each outlying station connected to a contact of said rotary switch corresponding, to the first digit of said designation number, means controlled by current in said circuit to cause said driving means 0t said rotary arm to be rectuated on the transmission of a sub sequent series of impulses and a second electrical circuit connecting a contact or" each or said rotary switches corresponding to the sum of the digits of said designation number to said indicating device.

2- In a selective signaling system the combination of a central station, a plurality of outlying stations each having a designation number, a commonline connecting said sta tions, means at said central station to transmit over said line a plurality of series of impulses, an indicating device at each of said outlying stations, a rotary selective switch at each of said outlying stations having a single rotary arm and a plurality of contacts, means to drive said arm' in response to the first series of impulses received from said central station, an electrical circuit at each outlying station connected to a contact of said rotary switch corresponding to the first digit of .said designation number, means controlled by current in said circuit to cause said driving means of said rota y arm to be reactuated on the transmission oi a subsequent series of impulses, a second electrical circuit connecting a contact or each rotary switch corresponding to the sum of the digits of said designation numberto said indicating device and means controlled by said first circuit to establish a current in said second circuit on he completion oi transmlssion ot a succeeding series of impulses.

In a selective signaling system the combination of a central station, a plurality of outlying stations each having a designation number, a common line connecting said stations, means at said central station to transmit over said line a plurality of series oi impulses, an indicating device at each 01":

said outlying stations, a rotary selective switch at each of said outlying stations having a single rotary member and a plurality of contactsyme ans' to rotate said arm in response to the first series of impulses received trom said central station, an electrical circuit at each outlying station connected to a contact of said rotary switch corresponding to the first digit oi said designation number, a second electrical circuit bination of a central station, a plurality of outlying stations each having a designation number, a common line connecting said stations, means at said central station to transmit over said line a plurality'ot series of im pulses an indicating device at each of said outlying stations, a rotary selective switch at each of said outlying stations having a single rotar arm and a plurality of contacts, means to drive said arm in response to the first series of impulses received from said central station, an electrical circuit at each outlying station connected to a contact of said rotary switch corresponding to the first digit of said designation number, means controlled by current in said circuit to cause said driving means of said rotary arm to be rte-actuated on the transmission of a subsequent series of impulses, a second electrical circuit connecting a contact oteach of said rotary switches corresponding to the sum or" the digits of said designation number to said indicating device, a spring controlled pawl adapted to hold said rotary arm in position after each series of impulses, an electromagnetic releasing device to withdraw said pawl and to restore said'rotary member to normal.

5. In a selective signalingsystem the combination of a central station, a plurality of outlying stations each having a designation number, a common line'connecting said stations, means at said central station. to trans mit over said line a pluralityot series of impulses, an indicating device at each of said outlying stations, a rotary selective switch at'eaoh of said outlying stations-having a sin le rotary arm and a plurality of contacts, means to'drive said arm in response to the first series of impulses received from said central station, an electrical circuit at each outlyingstation connected to a contact of said rotary switch corresponding to the first digit of said designation number, means controlled by current in said Circuit to cause said driving means of saidrotary arm to be re-actuated on the transmission of a subsequent series of impulses, a second electrical circuit connecting a contact or each of said rotary switches cor 'esponding to the sum of the digits of said designation number to said indicating device, a spring controlled,

pawl adapted to hold said rotary member in position after the series of impulses and an electromagnetic releasing device to withdraw'said pawl on response of the station selected.

6. In a selective signaling system the combination of'a central station, a pluralityot outlying stations each having a designation number, a common line connecting said stations, means at said central station to transmit over said line a plurality of series of current impulses, an indicating device at each of said outlying stations, arotary selective switch at each of said outlying stations having a single rotary arm and a plurality of contacts, means including an electromagnet to drive said rotary arm in response to the impulses received from said central station, a source of current, an electrical circuit connecting said electromagnet to said source of current and means to break said circuit automatically upon said rotary arm coming to rest after the transmission of the first of said series of impulses.

7. In a selective signaling system the combination of a central station, a plurality of outlying stations each having a designation number, a common line connecting said stations, means at said central station to trans; mit over said line a plurality of series of impulses,an indicatingdevice at'each ofsaid outlying stations, a rotary selective switch at each of said outlying stations having a single rotary arm and a plurality of contacts, means to drive saidarm in response to the first series ofimpulses received from said central station, an e ectrical circuit atfeach outlying station connected to a Contact of said rotary switch corresponding to the first digit of said designation number, means controlled by current in said circuit to cause saiddriving means of said rotary arm to be re-actuated on the transmission of a subsequent series of impulses, a second electrical circuit connecting a contact of each of said rotary switches corresponding tothe sum of the digits of said designation number to said indicating device, a. spring controlled paw] adapted to hold said rotary arm in position magnetic releasing device upon the move-' ment oi said key into the speaking position.

'8. In a selective signaling system the combination of a central station, a plurality of outlying stations each having a designation number, a common line connecting said sta tions, means at said central station to transmit over said line a plurality of serles of imposes, an mdicating device at each of said outl in stations, a rotar selective switch at each of said outlying stations having a single rotary arm and a plurality of contacts means to drive said arm in response to the first series of impulses received from said central station, an electrical circuit at each outlying station connected to a contact of.

said rotary switch corresponding to the first digit of said designation number, means controlled by current in said circuit'to cause said driving means of said rotary arm to be re-actuated on the transmission of a subsequent series of impulses, a second electrical circuit connecting a contact of each of said rotary switches corresponding to the sum of the digits of said designation number to said indicating device, a tens bar included in said first electrical circuit, and a units bar connected in said second electrical circuit, additional pairs of terminals, connecting links between the terminals of each pair, means to connect one terminal of one pair to a predetermined switch contact at each outlying station, means connected to the other terminal of said pair to apply current to said driving means when said rotary arm comes to rest on the predetermined contact of said rotary switch, and connecting means between said other pair of terminals and said indicating device.

9. In a selective signaling system the combination of a central station, a plurality of outlying stations each having a designation number, a common line connecting said stations, means at said central station to transmit over said line a plurality of series of current impulses, an indicating device at each of said outlying stations, a rotary selective switch at each of said outlying stations, having a single rotary arm and a plurality of contacts, an" electromagnet to drive said rotary arm in response to the impulses received from said central station, a source of current, an electrical circuit connecting said electromagnet to said source of current, means to break said circuit automatically upon said rotary arm coming to rest after the transmission of the first ofsai'd series of impulses, a, tens bar, a connecting link between one of said switch contacls corrcsource to said electroinagnel When said r0- sponding to the first digit of said designation tary arm rests on said contact correspond 10 number and said tens bar, a relay having ing to the first digit of said designation a coil element and a contact element, a secnumber. 0nd source of current, a second electrical cir- In Witness whereof, I have hereunto signed cuil; including said connecting link and the my name this 7th day of February 1921.

coil element of said relay and means con 4 I trolled by said relay to apply said second GEORGE WILLIAM FLYNN.

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