US1442770A - Automatic telephone and selective signaling system - Google Patents

Description

T. G. MARTIN( ATOMATIC TELEPHONE AND SELECTIVE SIGNALING SYSTEM.

2v SHEETS sHEn, r.

FILED Nov'. 30, A19o?.

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1 Jan.16,1928.. T. G. MARTIN.

AUTOMATIC TELEPHONE AND sELEcTTvE STGNALTNG SYSTEM.

'FTLEDAOM 3o. 19o?.

2 SHEETS-SHEET 2.

Patented dan. i6, 1923.

siren stare earaarorrica TALBUT G. MARTIN, 0F CHECAGO, ILLINOIS, ASSIGNR, MESNE ASSIGNMENTS, T0 AUTDMATEC ELECTRIC COMPANY, A. CORPORATEN OF LLINOIS.

AUTOMATIC TELEPHONE `,.flll) SELECTIVE SIGIIALIQ'G-SYSTEM.

Application mea november eo, 1907. serial no. @04,5121

To @ZZ whom 'it may concern.'

Be it known that L TALI-:or Gi MARTIN, a citizen ot' the "United States of America, and resident of Chicago, lCook Quintyj illinois, have invented a certain new and useful ler proyeiuent in tutomatic Telephone and Selective Signaling Systems, of which the ifollowing is a sneoiiication.

l/ly invention relates to telephone systems in general, but more particularly to automatic or seintautomatic telephone exchange sys s, and especially to systems in which sel we rinig/'ing` on partyllines is necessary or desirablev ,The y 'ncipal object oi my intention is to provide impro d arrangement by which the required rnr ing current `for the ringer ot' any particular substation on the party-line may be readily selected and applied to the called line. Y y

Special objects are to provide an automatic p-by-step switch 'for selecting and c i r nu' the diiii'ereut sources of ringing current to the linee c called lbscribers,

e the said autonrati swt/3h le c operative to connect any one of the dii-"f t sources of ringing; current lwith the party-line, whereby the ringrers thereon are selectively operated in any desired or well-lrnown inanner as? tor czmxnoleE by currents oit different frequencies; to pro` 'de a party-line automatic telephone system in which the calling1 oif all except the last digit oi: the called number will extend the connection from the called line to the party-line7 and in which the operation of the calling; subscriber-"s dial 'oir other.call-transmitting mechanism fior the last or final digit will then result in the selection of a certain one orn a number ot generators or other sources of ring-` iur; cnrgrnflt-` dependingupon which partyline su scriber is called and in th connection to the pa Aline of the particrlrr greneratcr or source ot ringing current thus arbitrarilyv selected by the calling subscriber; and to provide certain .details and combi'- bions and tentures ot improvement tendto increase the General efficiency of a party-line telephone system of this par `icular character.

To the. toren'oingv and other useful endsN my intention consists in matters hereinafter set forth and claimed.

ln the accompanying drawings Figure 1 represents diagrammatically a party-line equipped with a number of telephones A, A? and nii lelow the subscribers substatious there is represented central office quipment en'lployed in establishing a con- Aection. A first-selector switch vC is alottedto the line occupied by the substations fr, r1 and A2. At D there is represented diagrammatically a second-selector switch and at E a connector switch of an improved type. At B there is shown a central battery having its positive terminal preferably grounded at G.

Fig. 2 shows diagrammatically a second party-line equipped with the substations A3, A4 and n.5. To this line there is allotted at the central orlice the first-selector l l whicn is the same as the selector e. is the switch-hook is lowered the ceinarni e momentarlly presses the release springs 7, 8 and 9 into engagement, whereby the substation line conductors may be grounded simultaneously. When the switchhook is down the cam-arm 5 engages the spring 10, thereby bridging the ringer 11 in series with the condenser 12 across the line. Furthermore, when the switch-hook is down and said cam-arm 5 disengages the springs 13, 1e and 15, thus breakingthe local battery circuit which includes in series the' primary `winding 15a, transmitter 16 and local battery 17. lVhen the springs 13 and 1d disengage the lock-out relay 17"L is dis connected from the rotary line conductor. The substation `ground circuit is normally broken between the grounc springs 18 and l by the cam-arm 6; but when said springs are together, andthe relay 1Ta is in normal condition, ground is provided to the ground post 2O and to the release spring 7, as is usually the case in telephones of this type. rlhe seid substation comprises the usual induction-coil 21 having the primary winding 15a and secondary winding 22. Being an automatic substation it is provided with the usual vertical and rotary impulse springs 23 and 24. Said substation is, of course, provided with a dial (not shown) which is secured to the shaft 25, together with the locking vdog 26. Furthermore, there is a Vthat is secured to the shaft, which impulse wheel carries on its periphery the' socalled vertical impulse teeth 29 and one rotary impulse tooth 30. The said impulse teeth are `so arranged that when the dial is drawn down the impulse springs are not carried into Vcontact with the 'ground post 20; but as the dial returns, irst the vertical teeth engage the vertical impulse spring 23, and after they have completed their work the Arotary impulse tooth 30 operates the rotary impulse spring 24. ln this operation other.

given one ground impulse.

the subscribers vertical line conductor 31 is first given a number oi ground impulses, and then the rotary line conductor 32 is It will be seen that as long as the dial is out of normal position the dog 26 permits the primary circuit springs 33 and 34 toseparate, thus preventing the impulses that are vdelivered to either line conductor from passing to the rlhe means whereby the subscriber may signal the called subscriber comprises the push-button spring 35 which normally engages thel contact point 36; but when the button 37 is pressed the spring 35 engages the contact point 38, whereby the vertical line conductor 31 may be grounded. The substation is also provided with a governor (not shown) for controlling the speed of the impulse wheel 28and the switch-hoolr 3. Furthermore, the lock-out relay 17 a is provided With the armature 39, so that when the relay is energized and the switch-hook 3 is up, the armature 39 is attracted, disengaging the springs 40 and 41, and the armature is locked in its attracted position by the locking spring 42, as shown at substation A; but when the switclrliooh` is lowered the rod 43, which is attached to the switch-hook 3, slides downward in front oi the armature 39, carrying the locking spring 42 out 01"' engagement with the armature39.

The first-selector switch shown at C is or thegeneral type described in United States Patent No. 315,321, granted March" 13, 1906, to Keith, Erickson and Erickson, having some slight modiiications--that is, the rotary side of the line is retained normally open by the switch shaft, instead of being normally closed as is usually the case. Among other details, the iirstsselector switch C embodies the following well-known devices and circuits: The switch shaft (not shown) carries the vertical and rotary wipers 45 and and 46, respectively, and the private' wiper 47. The side switch is well known and comprises the` side switch wipers 48, 49,50 and 51, whichv may be designated as the vertical, rotary and private side switch wipers, and the rotary magnet wiper, respectively. The side switch is under the control of the private magnet 52, and in the normal or first position of the sidevswitch the wipers 48, 49, 50 and 51 occupy the contact points 53, 54, 55 and 56,y respectively; in the second position they rest on the contact points 57, 58, 59 and 60, respectively; and in the third position the contact points 61, 62, 63 and 64 are engaged by theirA respective wipers. rlhrough the medium of the vertical line relay 65, and while the side switch is in first position, the subscriber controls the vertical 85 magnet 66,which latter operates to raise the switch shaft and wipers 45, 46 and 47 vertically. By means of the rotary line relay 67, and while the side switch is in the first position, the subscriber controls the private magnet 52 and, therefore, the side switch. While the Vside switch is in second position the rotary magnet 68, which operates to carry the switch shaft and wipers 45,' 46 and 47 in a rotary direction, is energized. rlhe vertical and rotary line relays 65 and 67, acting conjointly, provide means whereby tlie subscriber controls the release magnet 681l while the side switch is in the firstV or second position. It the side switch passes to third position, then', since the selectoris oi the triink-1'elease type, the selector is controlled thmugh the next switch (with which latter a connection is then established) and through the private wiper 47 and by means of the back-release relay 69. The bridgecut-ori relay is provided to open the connection between the line relays 65 and 67 and between said relays and battery B. rlhis is desirable because if the relays are not discon'- `110 nected from each other and battery the ringing current for signalingl the subscriber may operate either or both of the relays 65 and 67, and thus cause some interference with the switch. It is also desirable to remove the 115 bridge formed through the said relays from across the line to give the voice-currents as clear a path as possible. ln addition, the selector switch is providedwith a private normal relay 71 by means of which the 120 guarding potential at the connector bank is momentarily removed to enable a subscriber to call back on his own line. The switch shaft also carries the normal arm 72 which, when the shalt is'in` normal position, retains 125 the'spring 73 out of engagement with the spring 74, thus disconnecting the rotary line conductor from the side switch wiper 49:

but when theshaft is given its first vertical step the springs 74 and 7 3 come together. 130

The second-selector D is of the same general type as the selector Switch C, with the exception that there are no normal conductors such as the normal conductors 75 and 76 of the selector switch C. There is also no necessity in the second-selector for a bridge-cutoff relay such as the relay 70 of the selector C, and it is also omitted; and the line relays are connected directly to battery lead. The private normal conductor, such as the private normal conductor 77 of the selector C, is not necessary in connection` with the second-selector and is also omitted. Since like parts are likewise represented throughout the drawings, the vertical magnet 7 8 and the rotary magnet 79, the release magnet 80, and the private magnet 81 will be recognized and understood. The said private magnet 81, of course, controls the side switch wipers 81a, 82, 83 and 84;, the said private magnet also controlling the circuit of the vertical magnet 7 8 in the usual manner by means of the springsV 85 and 86, but not the circuit of therelease magnet, for the release magnet spring is omitted. The vertical movement of the switch shaft and, therefore, of thewipers 87, 88 and 89 is controlled by the vertical magnet 78 and the rotary movement by the rotary magnet 79, the said rotary magnet circuit being provided with the usual interrupter springs 90. The operative magnets of the switch are, of course, controlled by the subscriber through the medium of the vertical and rotary line relays 91 and 92, as is well known. Said relays have under their control the usual springs 93, 94 and 95 and, in addition, the trunk-release springs 96 and 97, whereby the said switch may be 'released when the side switch wipers are in first or second position. lifter the side. switch passes to third position and connection is established with the next switch the release is controlled by the bacio release relay 98.

1`he connector switch E is an improvement upon the general type ofconnector switch disclosed in United States Patent No. 815,- 170, granted March 13, 1906, to Keith, Erickson and Erickson. In addition to the usual connector features my improved switch E possesses a frequency selecting arrangement which admirably adapts it to party-line work in which the signaling is selective. As shown in Fig. 1, the central oiiice may be provided with several ringer generators R1, R2, R3, R4, etc., each designed to deliver current of a different character or frequency. Also, the ringers at the different substations are arranged to respond` to generator currents of certain frequencies. For example, the ringer of substation $15 responds to the signaling current of generator R1. substation A4 is signaled from generator R2. and substation A3 is signaled only when the terminals of the generator R3 are bridged across the line. Hence, when it is desired to signal a. particular substation on a party-line the particular ringer generator ll, which is eii'ective in sounding the ringer of the desired station, is selected from the group and its terminals bridged across the called line. This frequency selecting arrangement which l have combined with the connector E comprises the rotary magnet 99 and ratchet release magnet 100. The rotary magnet 99, when energized, attracts its armature 101, whereby the pawl 102 engages the ratchet wheel 103, advancing 'the latter one step. As the ratchet wheel advances, the ratchet pawl 1011 retains the wheel in its advanced position. Mounted upon the shaft of the ratchet wheel 103 are the wipers 105 and 106 which are adapted to slide over a bank of contacts to which are connected the ringer generators lll, R2, liti" and R4. The ratchet release magnet 100, upon energizing, attracts the ratchet pawl 104, withdrawing the latter from engagement with the ratchet wheel 103. rlhe ratchet wheel then returns to normal position, with the wipers 105 and 106 to the left of the bank contacts 107, thereby restoring the generator selective arrange ment to normal position. rlhe connector switch shaft (not shown), like the selector switch shaft, carries the line wipers 108 and 109 and the private wiper 110. rlihe connector switch is also controlled by the calling subscriber through the medium of the vertical and rotary line relays 111 and 112. The vertical line relay 111 directly controls the vertical magnet 113, the rotary magnet .114., the rotary magnet 99 of the ringer lector, and the ringer relay 115. l. 1e purpose of the vertical magnet 113 is to give the shaft and shaft wipers their vertical motion, and the rotary magnet 11aA imparts to the shaft wipers a rotary or circular motion. As before explained, the rotary magnet 99 operates the ratchet wheel 103, and the ringer relay 115, upon energizing, operates to bridge the terminals of one of the ringer generators across the terminais of the called line. The rotary line relay 112 controls the private magnet 116, which latter, under certain conditions,y controls in turn the vertical magnet 113 and the two rotary magnets 111i; and 99, the ringer relay 115, the release magnet 117. and the side switch which comprises the wipers 118. 119, 120 and 121. The side switch of thc connector, unlike the side switch of the selectors C and D, has four positions. a nor mal or first position, a second position. a third position and a fourth position. The release magnet 117 is also controlled bv the vertical and rotary line relays 111 and 112 conjointly. By the use of the condensers 122 and 123 the circuitthrough the connector is divided into two sections. The

cw A

busy signaling apparatus H may be of any suitable design as, tor example, the one comprising the interrupter 124 in series with the primary winding 125 of the inductioncoil 126, whereby a busy signal is in turn induced in the secondary winding 127. The secondary winding is connected with the second-position contact point 1252 The operation ot' my improved partyline arrangement may be more clearly understood from. a description of its operation, as follows: To call the subscriber at substation A3, whose number it is assumed is 24213, the subscriber at substation A, whom it is assumed is doing the calling, removes his receiver from the switch-hook and operates his calling device once in the welllrnown manner for each digit. When the dial returns to normal position for the first digit the first-selector switch C is operated to establish connection with the second-selectorl switch D. The impulses for the second digit operate the second-selector switch D, while the impulses for the last three digits are directed toward the connector switch E, which operates to place its wipers in connection with the contacts corresponding to the desired line, and also to select the ringer generator R which is adapted to signal the substation A3. Still more in detail, the calling operations are as Jfollows: Then the subscriber removes the receiver 2 from the switch-hook 3, and operates the dial tor the iirst digit 2, the vertical line conductor 31 is grounded twice and the rotary line conductor` 32 is grounded once when the impulse springs 24 and 23 are pressed onto the ground post 20. As a result, the vertical .line relay 65 ot the first-selector C is energized each time by a flow of current from the substation ground G1 through the springs and 41, ground springs 18 and 19 to the ground post 20, impulse spring 23, vertical line conductor 31, side switch wiper 43, contact point 53, vertical line relay 65, bridge-cut-off springs 128 and 129 to the battery lead 130, thence through battery B to ground G. Each time that the vertical line relay 65 energizes, the line relay springs 131 and 132 are pressed into contact, thereby closing an energizing circuit through the vertical magnet 66 extending from ground G2 through the springs 131 and 132, private magnet springs 133 and 134, through the vertical magnet 66 to the battery lead 130, thence through battery B to ground G. The vertical magnet is thereby energized, and the wipers 45, 46 and 47 of the selector C are raised to the second bank level and brought opposite the first contact. Following the vertical impulses the rotary impulse spring- 24 is pressed onto the ground post 20, grounding the rotary line conductor 32 and energizing the rotary lline relay 67 of the selector C. The energizing circuit passes from ground G1 to the ground post 20, through the impulse spring 24 to the line conductor 32, normal springs 74 and 73, side switch wiper 49, contact point 54, rotary line relay 67 bridge-cut-of relay springs 135, 128 and 129 to the battery lead 130, thence through battery B to ground G. As previously eX` plained, when the selector shaft is given the rst vertical step the normal arm 72 permits the normal spring 73 to engage the spring 74, thereby connecting the rotary line conductor 32 with the side switch wiper 49. The rotary line relay upon energizing presses the line relay spring 136 onto the ground spring 131, thereby establishing an energizing circuit through the private magnet 52 from ground G2, throughthe springs 131 and 136, private magnet- 52 to the battery lead 130, thence through battery B to ground G. The private magnet, upon energizing an-d `cle-energizing, permits the selector side swith to pass from iirst to second position, whereby the side switch wipers and 51 engage the contact points 59 and 60, respectively. The closure of contact between the contact `point 51 and thev contact point sets up an energizing circuit through the rotary magnet 68 from ground G3 to the contact point 60, side switch wiper 51, interrupter spring 137, through the ro-r tary magnet 68 to the batterv lead 130, thence through battery B to ground Gr. Said rotary magnet 68 then operates to rotate the wipers 45, 46 and 47 into engagement with the .first Contact of the second level of the selector banks, from which'contact it is assumed that the trunk conductors 138, 139 and 14() lead to `the selector switch D. However, it the iirst trunk-line is busy and the wipers have to pass over busy trunk-lines, then as soon as the private wiper 47 engages the iirst busy private bank contact the private magnet 52 again energizes, locking the side lswitch in second position. The energizing circuit for the said private magnet extends from the grounded terminal of battery B through an occupying switch (not shown), through the private wiper 47, then through the back-release relay 69, side switch wiper 50, contact point 59, through the private magnet to the battery lead 130, thence through battery B to ground (i. Upon thus becon'iing energized the private magnet 52 locks the side switch wiper 51 in engagement with the contact point 60, whereby the rotary magnet 68 will be energized step by step until the wipers are caried beyond the last busy contact. Then, the instant that the private wiper 47 leaves the last bus;v contactpoint the energizing circuit through the private magnet 52 is destroyed, and as a result the selector side switch passes to third position. It there are no busy trunk-lines, as assumed, the primaarre vate magnet 52 releases the side switch to third position as soon as the wipers are car* ried into engagement with the first trunkline. As soon as the side switch passes to third position, as stated, the main line conductors 31 and 32 are extended to the conductors 138 and 139 which, in this case, lead to the second-selector switch D. Not only is the subscribers line extended, but a guarding potential is established at the private wiper 47 for protecting the seized trunk-line from interference by other calling` subscribers. This guarding potential extends from ground Gr4 through the side switch wiper 50, back-release relay 69 to the private wiper 47. 1t will be seen, of course, that the energizing circuit for the rotary magnet 68 is destroyed .when the idle trunk-line is seized-that is, when the side switch wiper 51 leaves the contact point 60. Also, when t-he side switch wiper 50 engages the contact point 63 a guarding potential is established at the connector bank to prevent a calling subscriber from establishing connection with the normal conductors 75, 76 and 77 while the selector C is busy. This potential extends ;trom ground G" through the: side switch wiper 50 to the conductor 144, through the springs 145 and 146, private normal conductor 77, which leads to the connector bank Contact corresponding to the line conductors 31 and 32. The grounding of the main line conductors 31 and 32 for the second digit 4 is el-l'ective in operating the selector switch D to establish connection with the trunk conductors 147, 143 and 149 which lead to the connector; E. Grounding the vertical line conductor 31 energizes the vertical line relay 91, which in turn operates to close an energizing circuit through the vertical magnet 78. rllhe vertical magnet 73 operates in the usual manner to carry the sha-tt wipers S7, 83. and 89 upwards four steps. Grounding the rotary line conductor 32 closes the energizing` circuit through the vrotary line relay 92, which in turn operates to close an energizing circuit through the private magnet S1. The private magnet operates as usuali to pass the side switch to second position, whereby an energizing circuit is closed through the rotary magnet 79, which operates lo place the shaft wipers 37, HS and S9 in engagement with the lrst idle trunk-line. then the side switch wipers 3l and 32 pass to third position the line `con doctors ill and 32 are extended to the con nector trunk-line conductors 147 and 14S. respectively, The grounding ot the main line conductors 31 and 32 for the next two digits 2 and 1 aliects the connector by operating` the vertical and rotary line relays 111 and 112. When the vertical line conductor 31 is grounded the vertical line relay 111 is energized by a flow ot current from the sub- Station ground G1, vertical impulse spring 23, conductors 3l, 138 and 147, through the winding of the vertical line relay 111 to the battery lead 130, thence through battery B to ground G. Each time that the vertical line relay operates, the vertical magnet 113 operatively energizes to carry the shaft wipers 108, 109 and 110 in a vertical direction, one step at a time, until the said wipers are carried two steps and thus brought to a level in which are located the terminals of the line #24213. The circuit through the vertical magnet extends trom ground G5 through the springs 150 and 151, through the private springs 152 and 153, side switch wiper 121, vertical magnet'113 to the battery lead 130, thence through battery B to ground G. When the rotary line conductor 32 is grounded, following the grounding of the vertical line conductor 31, the connector rotary line relay 112 becomes energized over a circuit extending :from ground `Gil to the impulse spring 24, conductors 32, 139 and 148, through the winding of the rotary line relay 112, springs 154 and 155 to the battery lead 130, thence through battery B to ground G. The rotary line relay upon energizing oper-ates to close an energizing circuit through the private magnet 116, which lat ter in turn operates to release the side switch from first to second position. The energizing` circuit through the private magnet 116 extends from ground G5 through the springs 150 and 156, through the private magnet 116 to the battery lead 130, thence through battery B to ground G. For the next digit the subscriber operates the dial as previously explained, grounding the vertical line conductor once and the rotary line conductor 32 once. The connector vertical and rotary line relays 111 and 112 are operated over previously traced circuits. However, when the vertical line rel-ay 111 operates, a circuit is closed through the rotary magnet 114 instead of through the vertical magnet 113, since the side switch wiper 121 has passed from first to second position. Vhen the rotary magnet114 is energized the shaft wipers 108, 109 and 110 are rotated one step and the said wipers are carried into engagement with the normal conductors 157, 153 and 159, thc first two oit which lead to the .main lino terminals et the desired substation. The rotary line relay 112, upon energizing. rfnnpletes which latter now `perates with one of two results, namely the release oi the side switch from second to third position, or the socalled busy-release oit the connector. It will be assumed, that the former result occurs, and that the side switch passes to third position` whereby the side switch wipers 120 and 121 are placed in connection with the contact points 160 and 161, respectively, and

au energizing circuit through the private magnet 116, as before,

, tained. as shown.

wiper 120, private the Wiper 120 is placed in connection with the contact 160, thus establishing a guarding potential ttor protecting the called. line. This potential extends from ground G to the side switch wiper 120 and the private shat't wiper 110, which engages the private contact ot the called line. For the last digit 8 the dial is again operated, grounding the vertical line conductor 31, which operates the vertical line relay 111, as explained. The vertical line relay, upon energizing, operates to close an energizing circuit through the rotary magnet 99 extending from ground G5 through the springs 150 and 1 51, private magnet springs 152` and 158, side switch wiper 121. contact point 161, through the winding of the rotary magnet 99 to the battery leadl 180, thence through battery B to ground G. The vertical line relay being energized three times, the rotary magnet 99 is in turn` also energized three times, whereby the ratchet wheel 103 is given three steps, and the wipers 105 and 106 are placed in Contact with the bank terminals 162 and 163 to which is connect-ed the ringer generator R3. The rotary line relay, upon energizing for the last digit, again operates to close an energizing circuit through the private magnet, which latter, upon energizing and deenergizing, permits the side switch to pass to fourth position. Ot course, when the side switch passes to third position the guarding potential 'for the called line is still main- Also, when the shaft wiper 110 engages the private Contact, and the side switch wiper 120 passes to third position, an energizing circuit is then established through the bridge-cut-oti' relay 164 o1 the selector F (Fig. 2). This circuit extendsfrom ground GG through the side switch shaft wiper 110, private trunk conductor 159, through the spring 165, side switch wiper 166, conductor 167 through the bridge-cut-ott rel-ay 164 to the battery lead 180, thence through battery B to ground G. The calling subscriber having operated the calling device in accordanee with the digits ot the desired number 24218 is now ready to signal the subscriber at substation A, which is done by pressingr the button 37,\whereby the spring 85 is carried onto the ground contact. point 88, thereby grounding the vertical line conductor 81 and completing an energizing circuit through the vertical line relay 111. It will be remembered that the connector side switch has passed from third to 'fourth position, and that the side switch wiper 121 now ei'igages the contact point 168, thereby placing the vertical line relay 111 in control ofthe ringer relav 115 in the same manner in which the rotary magnet 114 came under the control of the vertical line relay when the side switch passed 'frein-first to second position. Therefer6, when the vertical line relay 111 presses the springs 150 and 151 into contact, the ringer relay 115 is energized by a flow ot current trom ground G5 through the springs 150 and 151. private magnet springs 152 and 153, side switch Wiper 121, contact point 168, through the ringer relay 115 to the battery lead 180, thence through battery B to ground G. rllhe ringer relay, upon energizing, operates to shift the springs 169 and 170 from the springs 171 and 172 to the springs 178 and 174C, and the springs 154 and 155 are also disengaged. The shitting ot the springs 169 and170 results in bridging the terminals oi the ringer generator R3 across the :a-lled line. The signaling current is, theretore, sent from the generator R3 to the bank contact 162. wiper 105, through the ringer relay springs 17 4 and 170, side switch Wiper 118, shaft wiper 108, normal conductor 157, main line conductor 175, through the switchhool; 176, spring 177, through the ringer 178, condenser 179 to the rotary line conductor 180, normal conductor 158, shatt Wiper 109, side switch wiper 119, ringer relay springs 169 and 17 8, wiper 106, bank contact 168 and back to the ringer generator R3. The signalingl current also passes through the ringers 181 and 182 ot the substations A4 and A5 in multiple with the ringer 178 of substation A3; but, as previously explained, only the ringer 178 is arrange-d to respond to signaling current 'from the ringer' generator R3, and hence only the ringer at substation A3 is sounded. As'soon as the calling subscriber ceases to press the signaling button 85, the ringer relay 115 becomes ele-energized, and the springs 169 and 170 return to their normal positions. rfhe subscriber at substation fr. in response to the signal, removes the receiver 188 from theA switch-hook 1811,

'whereby the switch-hook rises and permits the springs 185 and 186, and also the springs 187, 188 and 189, to engage. The engagement ot the springs 185 and 186 closes a secondary circuit which includes the receiver 188 and the secondary Winding 190. The engagementof the springs 187, 188 and 189 closes the primary circuit which includes the transmitter 191, local battery 192 and the primar;v winding.r 198. The twii subscribers are now connected and conversation may be carried on over the circuits shown by the heavy liuc conductors in Figs. l and 2. Suppose that. while the two sub-- stat-.ions are thus connected the subscrilgier at substation ,f3.1 (Fig. 1l removesl his receiver trou: the switcli-hoolt. preparatory to making a call. lu that event, an energizing circuit is established. through the ground cut-oil relay 194 extending 'trom ground G7 through the springs 195 and 196 and the springs 197 and198, through the cut-ott relay 194, springs 19.9.and 200wto the rotary line conductor 82, trunk conductors 189 and 148, through the rotary-line relay 112 to the battery lead 190, thence through battery l to ground (l. The relay 1911 thereupon energizes, attracting its armature 201 Awhich operates to separate the springs 195 and 196, thereby opening the circuit through the relay 19e and disconnecting the substation ground G7 troni the ground spring 202, whereby the substation is deprived of ground connection for operating the central otlice switches. rlhe substation is thus rendered powerless to interfere with the established connection. Also, when the relay 19eL energizes, theA spring 203 rises in front oit the armature 201, locking the latter in its attracted position. lllhen the receiver Vis restored to the switch-hook the arni 20e carries the locking spring 203 out oli engagement with the armature 201, and the springs 195 and 196again engage. Also, a subscriber at substation AS* on the called line is prevented from interfering with an established connection, since the bridge-cut-ott relay 164; ot the tiret-selector F is energized, and the 1vertical and rotary line relays 205 and 206 are disconnected troni the battery lead 130. The release ot the central office switching` apparatus is Abrought about when the calling subscriber restores the receiver 2 to the switch-hook 3, thereby pressing the release springs 7, 8 and 9 into engagement for a moment. The contact of the said springs grounds the vertical and rotary line conductors 31 and 32 simultaneously from ground G1 to the releasespring 7, thence through the springs 8 and 9 to the vertical-'and rotary linerelays 111 and 112. Said relays, upon energizing siniultaneously` press the springs 207 and 208 into contact, whereby an energizing circuit is established through: the release niagnet 117 of the connector E in series with the back-release relay 9S of the second-selector l). This circuit eztends troni ground G8 through. the side switch wiper 83, back-release relay 98, shaft wiper S9, conductor 149, trunkfrclease springs 20'? and 208, through the release magnet 117 to the battery lead 130, thence through battery B to ground G. i/Vhen the connector release magnet is thus supplied with current it energizes, and as a result the switch sha'tt and side switch are restored to normal position, thus breaking the connection. between. the connector switch shaftt wipers 108, 109 and 110 and the norinal conductors 157, 158 and; 159. rlhe en gageinent ot the trunlorelease swings 207 and 208 also closes an energizing circuit tlirough the release magnet 100. rllhis circuitl extends from ground GS through the back-release relay 98, trunk-release springs 20.7 and 20S. through the winding` oit the release magnet 100 to the battery lead 180` thence through battery B to ground (i: rThis rnagnet, upon energizing, draws the ratchet pawl. armature 104Y out oicengagew `nient with the ratchet tooth ot the wheel 103. rlhe ratchet wheel 103 now returns to norinal position, with the wipers 105 and 10o to the lett ot the contacts 101. r.the

lbach-release relay 98, being in the saine cirtery lead 130, thence through battery B to ground G. When the back-release relay (i9 energizes and places the springs 211 and 212 in contact an energunn,sr circuit is established through the release magnet 68 ot the lirst selector This circuit troni ground G through the springs 211 and 212, release niagnet 68 to the battery lead 130. thence through battery B to ground G. liilhen the ground connection to the line conductors 31 and 32 is interrupted all the magnets ini'olved in the release are cle-energized and all the switches fully restored.

It the line to which the substation fr., is allotted busy at the tinie the calling subscriber at substation A. attempts to establish a connection, the connectoi-Eis released by the rotary impulse for the next to the last d j" .Said impulse energizes the rotary line relay 112, which relay in turn energizes the private magnet 116, pressing the private sprin .213 and 214 into engagement after the private wiper 110 has been carried onto the grounded private bank contact. lt is understood, of course, that whenever a line is busy the connector private bank contacts connected with the private normal conductor are all connected to ground, There- ;tore, since the connector side switch is in second. position when the private inagnot springs 213 and 214: are brought into contact, an energizing circuit is established through the release magnet 117 troni the said grounded private bank contact tothe private wiper 110, through the side switch ii'ipcr .li/50, which is in second position, to the routac point 260. throu ..h the prii'aie magnet sguiu 2t! aud 2125. through the release ruafguey il? to the batteri;Y lead 1250.4 thence through hat :er f to oiiound til. lilhen the releasii mafw (n 1: net energized thc cmniector switch. shattand side switch :ire released aud connection is not established through the called line, and the connector' mechanism returns to normal position. New, when the suliscril'ier operates the dial tor the last digit 8 the connector` vertical. and. rotary line relays are energized, and the vertical magnet is given three steps and the private magnet .isY energized once. The'energization and cle-energization of the completing an energizing circuit through the vertical relay, which in turn operates to close an energizing circuit through the rotary magnet 114 instead of through the ringer relay 115. The calling subscriber, waiting to receive a response from the called subscriber, receives the busy-signal instead, as follows: From the battery lead 130, through the secondary winding 127 of the induction-coil 126, contact point 125L (remembering that the side switch is now in second position) to the side switch wiper 119, ringer relay springs 169 and 171, through the condenser 123, trunk conductors 148 and 139, rotary line conductor 32, condenser 12, through the receiver 2, secondary winding 22, through the springs 33 and 34 tothe vertical line conductor 31, thence through the trunk conductors 138 and 147, through the winding of the vert-ical line relay 111 to the battery lead 130. @t course, when the calling subscriber hangs up his receiver after receiving the busy-signal, he grounds the vertical and rotary line conductors 31 and 32, thereby energizing the vertical and rotary line relays 111 and 112 of the connector E, as already explained, producing a release of the switching apparatus as formerly.

From the foregoing it will be seen that I provide astep-by-step and automatic switch for enabling the calling subscriber, or any other person, to select the desired generator or source of ringing current and connect the same with the called line, Also, it will be seen that this switch for selecting and connecting the generators or sources of ringing lso called number,

current with the called lines is subject to substation control.k llVith this arrangement a subscriber, in calling a party-line subscriber, operates his dial for all of the digits of the called number except the last, and thereby operates the trunking means for iinding the called line. When the dial or calling mechanism of the calling subscriber is then operated ilor the last digit of the this results in the selection by the calling subscriber oi the desired generator, aud in the crinnection of the saine with the party-line Then when the calling subscriber presses his ringing button, the proper or desired 'frequency of current '[*lows out Vupon the party-line, and only the ringer at the substation of the calledy subscriber responds. In other words, when the subscril'ier rotates his dial for the last digit of the called number, these-called vertical impulses cause the vertical line relay of the connector to operate naief/7o in the trunk circuit between the two lines,

and at the same time selects the proper generator for use in ringing the bell at the station of the called subscriber. 0i course, the connection of the generator to the'contacts of the ringer relay occurs just ahead of the movement of the side switch to fourth position. Also, the' iow of ringing current in the called line does not occur until the calling subscriber presses his button or ringing key.

lVhat l claim as my invention is`:-

1. In a telephone system, a party-line equipped for selective signaling, means by which a calling subscriber calls any partyline subscriber by transmitting electrical impulses, means responsive to all except the last impulses for inding the party-line, means responsive to the impulses for the last digit for selecting the means by which to signal only the called subscriberL on said line, and a trunk-release circuit for restoring the central oflice signaling means to normal condition.

2. lni a telephone system, a party-line equipped for selective signaling, automatic means Jfor finding the `line in accordance with all except the last digit of the number oit any subscriber thereon, means for signaling across the line in accordance with the last digit ot such number, and a trunlrrelease circuit for restoring the central office signaling means to normal condition.

3. In a telephone system, a party-line equipped for selective signaling, automatic means for trunking a calling subscriber to the said line in accordance with all except the last digit `ot the number of any subscriber thereon, means for signaling across the line in accordance with the last digit oi such number, and a trunk-release circuit tor restoring the central oilice `signaling `means to normal condition. i

4. In a telephone system, a party-line equipped for selective signaling, subscribercontrolled automatic means for finding said line in accordance with all except the last digit oi the number oifany subscriber there` on, suitable means for signaling across the line in accordance with the last digit of such number, and a trunk-release circuit for restoring the central oiiice signaling means to normal condition` 5. In a telephone system, a party-line equipped 'for selective signaling, suitable vmeans for connecting with the said line in accordance with all except the last digit of the. number of any subscriber thereon, subscriberecontrolled means for signaling across the line iii accordance with the last digit of such number', and a trunk-release circuit for restoring the central oii'ice signaling means to normal condition.

l6. In a telephone system, a connector including relays and provided with a side switch having only four positions, means Jfor controlling said connector in accordance with the iirst two of the last three digits of the number of a called subscriber, and another switch controlled by a relay of the connector in accordance with the last digit after the called line is found.

7. In a telephone system, an automatic connector provided with a side switch having only four positions, a party-line adapted to be seized by said connector, and means for controlling said connector in accordance with only the first two of the last three digits of the number of any subscriber on said line.

8. In a telephone system, an automatic connector provided with a side switch having four positions, means for moving said Side switch from one position to another to enable the connector to nd the called line, and means for signaling the called subscriber after the side switch moves to fourth position.

9. In a'telephone system, an automatic connector provided with a side switch having four positions, means for moving the side switch from one position to another to enable the connector to find the called line, a plurality or sources of ringing current, means operative when' the side switch is in third position for selecting any source et current, and means for projecting said ringing current onto a called line after the side switch has moved to fourthl position.

10. The combination, in an automatic telephone exchange, of a party line equipped for selective signaling, means to signal the called subscriber, a calling subscribers mechanism and means responsive thereto for inding the said party line, means responsive to said mechanism for selectingr the means to signal only the called subscriber on said line, operative only after the called line is found, and a trunk-release circuit including a third conductor for restoring the central oiiice signaling means to normal condition.

ll. The combination, in an automatic telephone exchange, of a party line equipped for selective signaling, means by which a calling subscriber calls any party line subscriber by transmitting electrical impulses, means responsive to all except the last impulses ior finding the party line, means rasponsive to the impulses Jfor the last digit for selecting the means by which to signal only the called subscriber on said line. operative only ait-.er the called line is found, and a trunk-release circuit including a third conductor for restoring the central office signaling means to normal condition.

l2. The combination, in an automatic telephone exchange, oi a party line equipped for selective signaling, a calling mechanism, means responsive to said mechanism for finding the party line, as many different sources oiringing current as there are subscribers on said line, means responsive to said mechanism Afor selecting the source oi? current by which to signal only the called subscriber on said line` operative only after the called line is found, and a trunk-release circuit including a third conductor for restoring the central oiiice signaling means to normal condition.

13. The combination, in an automatic telephone exchange, of a party line equipped for selective signaling, automatic means for finding the line in accordance with all except the last digit of the number of any subscriber thereon, means for signaling in accordance with the last digit of such number, operative only after the called -line is found, and a trunk-release circuit including a third conductor tor restoring the central oihce signaling means to normal condition.

14. The combination, in an automatic telephone exchange, of a party line equipped for selective signaling, automatic means for trunking a calling subscriber to the said line in accordance with all except the last digit of the number of any subscriber thereon7 means for signaling in accordance with the last digit of Such number, operative only after the called line is found, and a trunkrelease circuit including a third conductor for restoring the central oiiice signaling means to normal condition.

15. The combination, iii an automatic telephone exchange, of a party line equipped for selective signaling, subscriber-controlled automatic means for Ending said line in accordance with all except the last digit oi` the number of any subscriber thereon, suitable means for signaling in accordance with the lastdigit of such number, operative only after the called line is found, and a trunkrelease circuit including a third conductor for restoring the central otlice signaling means to normal condition.

16. The combination, in an automatic telephone exchange, of a party line equipped for selective signaling, suitable means for connecting with the said line in accordance with all except the last digit of the number of any subscriber thereon, subscriber-controlled means for signaling in accordance with the last digit of such number, operative only after the called line is found, and a trunk-release circuit includinga third conductoi` for restoring the central oiiice signaling means to normal condition.

1T. The combination, in an automatic telephone exchange, of a connector provided with a side switch having :tour positions, and means for controlling said connector in accordance with only the first two of the last three digits of the number of the called subscriber to iind the called line.

18. The combination, in an auton'iatic telephone exchange, of an automatic connector provided with a side switch having four positions, a party line adapted to be seized by said connector, and means 'for controlling said connector in accordancewith only the first two of the last three digits or' the number of any subscriber on said line to find the called line.

19. The combination, in an automatic telephone exchange, of an automatic connector provided with a side switch having four positions, means for moving said side switch from one position to another to en able the connector to find the called line, and means for signaling the called subscriber while the side switch is in fourth position, operative only after the called line is found.

20. In a telephone system, a calling subscribers line, a party line, a linal connector switch, a line relay individual to said connector, ay circuit for said relay including a conductor of the calling line, operating'magnets insaid connector controlled by said relay 'responsive to trains of impulses transmitted over said circuit for setting the wipers of said connector on party line, dilierent sources of ringing current equal in number to the stations on said party line, an auX- iliary ringing current selecting switch, a magnet for shifting the control of said relay Yfrom the connector operating` magnets to the operating magnets of said auxiliary switch in order to select one of said sources responsive to another train oit' impulses, and means for connecting the selected source to the said party line to signal the desired station.

21. In a telephone system, a calling subscribers line, a party line, a final connector switch, a line relay individual to said connector, a circuit for said relay including a conductor of the calling line, operating magnets in said connector controlled by said relay responsive to trains of impulses transmitted over said circuit for setting the wipers of said connector on said party line, diitlern ent sources of ringing current equal in number to the stations on said party line, an auxiliary ringing current selecting switch, a magnet for shifting the control of said relay tromthe connector operating magnets to the operating magnet of said auxiliary switch in order to select one ot said sources rcsponsive to another train of impulses, and a ringing relay controlled by said line relay thereafter to bridge the selected source across the wipers of said connector to signal the desired station on said party line.

22. In a telephone system, a trunk line terminating in a connector switch, a party line accessible to said connector, operating magnets in said connector, a line relay in said connector responsive to trains of impulses transmitted over a conductor of said trunk line for actuating said magnets to cause the connector to connect with said party line, different sources of ringing current equal in number to the stations on said party line, a ringing current selecting switch, an operating magnet in said selecting switch controlled by said line relay responsive to a subsequent series of impulses for causing said selecting switch to select one of said sources, a magnet for shifting the control oli' said line relay from the last connector operating magnet to the operating magnet of said selecting switch at the proper time, and means ior connecting the selected source to the said party line via the wipers of said connector to signal the corresponding station.

23. In a telephone system, a ltrunk line terminating in a connector switch, a party line accessible to said connector, operating magnets in said connector, a line relay in said connector responsive to trains of impulses, transmitted over aconductor of said trunk line for actuating said magnets to cause the connector to connect with said party line,different sources of ringing current equal in number to the stations on said party line, a ringing current selecting switch, an operating magnet in said selecting switch controlled by said line relay responsive to a subsequent series of impulses for causing said selecting switch to select one of said sources, a magnet for shifting the control of said line relay l'rom thel'ast connector operating magnet to the operating magnet of said selecting switch at the proper time, and a ringing relay controlled by said line relay for connecting the selected source to Said party line via the wipers of said connector to signal the corresponding station.

24. In a telephone system, a trunk line terminatingl in a connector switch, a party line accessible to said connector, a line relay in said connector responsive to successive trains of impulses transmitted over said trunk line, different sources of ringing current, a ringing current selecting switch,'oper ating magnets for said connector and `said selecting switch controlled successively by said line relay to set said connector on said party line and select a particular one of said sources, a magnet for shitting the control of said line relay i'rom the last connector operating magnet to the selecting switch operatingmagnet at the proper time, and means for connecting the selected source to said party line to signal a particular one of said stations.

25. In a telephone system, a trunk line terminating in a connector switch, a party line accessible to said connector, a line relay in said connector responsive to successive trains 'of impulses transmitted over said trunk line, sources of ringing current of diii'erent character, a ringing current selecting switch having two wipers, operating closing said circuit in the connector to signal 10 magnets for said connector and selecting a particular station on said party line. switch controlled successively by said line re- Signed by me at Chicago, Cook County,

lay to set said connector on said party line Illnois, this 26th day of November, 1907 and to select a particular one of said sources,

a signalling circuit including the two wipers TALBOT G' MARTIN of said selecting switch and the line wipers lVitnesses: of said connector for bridging the selected JOHN ERICKSON,

source across said party line, and means for EDWARD D. FALEs.

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