US1176260A - Automatic telephone system. - Google Patents

Description

C. S. WINSTON. Auromnc TELEPHONE SYSTEM.

APPLICATION FILED FEB. 24. I911- Patented Mar. 21,1916.

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1. UNITED STATES PATENT OFFICE.

CHARLES S. WINSTON, OF CHICAGO, ILLINOIS, ASSIGNOR T0 KELLOGG SWITCHBOABD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Mar. 21, 1916.

To all whom it may concern Be it known that I, CHARLES S. "Wrnsrorr, a citizen of the United States, residing in Chicago, county of Cook, State of Illinois,

have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a specification.

My invention relates to automatic telephone systems of the type known as twowire or metallic line systems in which directively controlled switches at the exchange are operated responsive to interruptions of the line circuit by means of a calling device or other suitable means.

My invention is particularly applicable to systems using automatic switches in which the wipers are adjusted in a primary direction to select a group or row of contacts and are then adjusted in a secondary direction to select a contact of a group or row, and in which to release the switches, the wipers are advanced in the secondary direction until they have passed beyond the last contact of the row when they are automatically restored by means of; spring tenslon or gravity.

In an application of William Kaisling for switch for automatic telephone systems, Serial N 0. 600564. a switch of theztype above referred to is illustrated, and my invention is adapted to be used in connection with a switch of the type therein illustrated. My'

system is adapted for use with other switches of the type referred to and I do not desire to be limited to the structure disclosed in the said Kaisling application.

My invention is illustrated in the accompanying drawings, comprisin Parts 1, 2 and 3, which to be readily fol owed out are to be laced with Part 2 in the middle, Part 1 to tie left of Part 2, and Part 3 to the right of Part 2. Part 1 illustrates a line switch and first selector; Part 2 a second selector, and Part 3, a connector switch and called sub-station with its line switch.-

The system as illustrated is adapted for use as a ten-thousand line exchange system, and there would be a line switch 0 for each line of the exchange. T hen on a basis of ten per cent. trunking there would be one thousand first selectors D, one thousand second selectors E, and one thousand connectors F,

divided into one-thousand groups and one- 5 hundred sub-groups in a well known manner.

In extending a connection from calling sub-station A to called sub-station H, the switch hook at sub-station A is operated, thereby causing its line switch C to automatically connect with an idle first selector D. A subscriber at sub-station A, by the operation of his calling device, operates the connector first selector D to connect with an idle second selector E. By a further operation of the calling device the calling subscriber operates a connected second selector E to extend the connection to an idle connector switch E, having access to the line of the called sub-station. By a further operation of the calling device the calling subscriber now actuates the selected connector switch F to connect with the line of the called sub-station H. If the called line is busy, a characteristic busy signal will be automatically transmitted to the calling substation and the calling subscriber may re lease all of the switches which were used in establishing the connection by replacing his receiver upon its switch hcok. Should the called line be idle, the call bell of the desired sub-station is automatically operated by applying ringing current to the terminals of the called line, and upon a response from the called sub-station the ringing current is automatically disconnected. The subscribers being connected for conversation, when desired may release the switches which were used in establishing the connection. The release of the line switch C, first selector D and second selector E is controlled at the calling sub-station A and the release of the connector switch F is controlled at the called sub-station H.

Each sub-station A comprises a well known form of sub-station telephone, having a switch hook 1, receiver 2, impedance coil 3 and condenser 4 and also includes the transmitter 5 and call hell 6, which are adapted to be connected in and out of circuit by means of the switch hook 1. Each sub-station A also includes a calling device, comprising a spring return dial 7, and impulse springs 8. The calling device is so arranged that when the dial 7 is rotated in a clockwise direction, the insulated projections on its periphery do not open the impulse springs 8 but upon the return of the dial 7 after it is released by the operator, each insulated projection opens the contact springs 8 a single time. In other words, if in advancing the dial 7, five projections pass the springs 8, upon the return of the dial the connection between the said springs 8 is interrupted five times. Each sub-station is connection with an exchange by means of line limbs 9 and 10 which terminate at a line switch C, and arealso multiply connected to terminals 11, 12 and 13 of connector switches having access to the-line of the said sub-station.

Each line switch C includes a line relay LR which is adapted to be energized upon initiation of acall from the connected sub: station, a catch relay G0 which is adapted to remove the sub-station control or relay LR, a motor magnet MM: which is' adapted to advance the wipers of the switch, a release relay R which controls the restoration of the wipers to normal and on normal con tacts ON which are adapted to move to their alternate position upon the first step of switch C off normal.-

The wipers 14, 15 and 16 are mounted on a single shaft having a suitable ratchet wheel secured thereto and connected to a suitable driving pawl of motor magnet MM. The bank contacts 17, 18 and 19 are arranged in three rows, each row being adapted to cooperate with the said wipers let, 15 and 16 respectively. Each row of contacts, contain ten such contact sets, while each row also has a normal contact 17','18' or 19'. It will he noted that each wiper has three projecting arms each carrying a wiper cndand the bank contacts are so positioned that when the wipers are advanced, upon one wiper arm leaving the last bank contact, the preceding wiper arm is in a position resting upon itsnormal bank contact 17', 18, or 19. The wiper ends H are so shaped that when advanced from one contact to the next, they make connection with one contact before breakin connection with the preceding contact. 'lhe line wipers 15 and 16 are arranged that in advancing they break connection with one contact before making connection with the succeedin contact in the row. The motor magnet M81 and mechanism is so arranged that for each energization and deenergization of magnet MM, one step of wipers 14, 15 and 16 is effected, each such step advancing the wipers from one set of contacts to the next. In the operation of line switch C, the wipers are moved to connect with one of the'bank contact sets and thereafter to restore the switch, the wipers are again advanced until the engaged arms advance one step beyond the last contact in the bank, when as previously stated the preceding arms connect with the normal contacts in the bank and the switch remains thus. The off-normal switch ON is so con nected with the wiper shaft that upon the first movement of the said shaft ofi normal,

the said-switch assumes an alternate posi-*- tion, retaining this (position until the wipers are again advance to a normal position, when the said ofi' normal switch is thereby restored to its normal position.

In the system of my invention I divide the telephone lines in to groups of one hundred in a well known manner and I provide ten first selectors D for each one hundred lines. Therefore, each such first selector D would be multiply connected to the bank contacts of one hundred line switches U, although in the illustration I have shown but two such multiple connections, and of course there being ten contact sets 17, 18, 19, each switch C has access to ten first selectors D. Each first selector D includes a primary relay PR, which-is in bridge of the talking conductors and when connected with a calling line is controlled at the sub-station thereof, to transmit the primary or directive impulses for controlling the switches in extending a connection to a called line. Each switch D also includes a main release relay MRR which is controlled at a connected calling sub-station through the medium of a relay PR. Release relay RR when operated, controls the release of its switch. Primary magnet PM, is adapted when operated to adjust the wipers 20, 21 and 22 of the switch in a primary direction to select a group or row of contacts, determined by the number of impulses transmitted, while the secondary magnet SM when operated advances the wipers in a. secondary direction to connect with a set of contacts 23, '24, 25 in the selected row, leading to an idle second selector switch E. Secondary relay SR, is a slow relay, came in which the armature is momentarily'held attracted after its energizin circuit is interrupted, the said relay SR being adapted to control the starting of the said secondary movement of the wipers. Busy relay BB is adapted to control the operation of magnet SM in selecting an idle set ofbank contacts. Each first selector D has a'private or busy wiper 20 and a pair of line wipers 21 and 22. The contact bank of switch D includes one hundred sets of contacts 23, 24 and 25,-being arranged in ten groups or rows of ten contact sets each. The prlmary ofl normal switch PON is adapted upon the first primary movement of wipers 20, 21 and 22, to move to an alternate position, while the secondary ofi' normal switch SON is adapted upon the first secondary step of said wipers to move to an alternate position. Each first selector D having one hundred sets of bank contacts 23, 24, 25, would of course have access to one hundred second selectors E. tor E would he multiply connected to the bank contacts of ten first selectors D although I have illustrated but two such multiple connections. The second selector E includes a contact bank and cooperating Each such second sclec- 1 wipers, similarly arranged to the contact banks and wipers of the first selectors D. The operatin relays and magnets ofv second selector i which have functions corresponding to similar relays and magnets of first selector D, have corresponding reference characters but include the sutlix This is also true of the off normal switches.

Each connector switch F includes relays,

and off normal switches having functions corresponding to the rela '5, etc., of the first and second selectors, an in the said switch F these parts have corresponding reference characters but with the suflix The bank contacts and cooperatin wipers of connector switch F are arrange similar to the bank contacts and wipers of the other switches. Connector switch F has in addition to the magnets, relays, etc., referred to, several other relays, including a switching relay SlV which is adapted to disconnect the primary magnet PM and connect the secondary magnet SM to the upper heavily marked conductor, so that the may be'operated in their proper sequence y the current im )ulses. The test relay TR is adapted to )0 operated by a secondary impulse to test acalled line for its idle or busy condition, and thereafter if the line be busy it controls the application of busy signals from busy back BB, or if the line be idle the so called fliptlo or interrupter relay FF, is operated to alternately connect ringing current and the ringing control relay R0 to the terminals of the called line. The operation of the other relays of switch F will he more particularly pointed out in the description. of the operation of the system. To each group of one hundred lines there are ten such connector. switches F, the hundred lines of each group bein multiply connected to bank terminals 0 the ten associated connector switches, although in the illustration but two such multip e connections are shown.

The called sub-station H includes apparatus similar to that of calling sub-station A, but the reference characters of the substation H having the sulfur The line switch C is similar to line switch C, the corresponding parts of switch C having reference characters corresponding to those of line switch C but having the sufiix While I have indicated a plurality of batterics, it is to be understood that they may be one and the same, this also being true of the magnet operating alternating current generators.

It is to be understood that although I have shown some of the apparatus connected to ground, in practice this apparatus would be connected to the grounded pole of the battery.

Operatiom-Having described in general the apparatus used in the different types of magnets,

switches and'sub-stations, the operation of the'systcm in establishing a connection between a calling and called sub-station will now be described.

Assuming that sub-station A is a calling sub-station and a subscriber thereat desires connection with a subscriber at sub-station H, whose number we will assume is 23 13, the subscriber at A removes receiver 2 from its switch hook 1, thereby closing the upper contacts of the switch hook and establishing a circuit for line relay LR, traced from round at normal contact 26, line conductor 10, sub-station A, line conductor 9, normal contact 27, normal contact .28 of relay R, through the winding of line relay LR to battery, energizing the said relay. Responsive to this energization of relay LR, a circuit for motor magnet MM is established, from ground through alternate contact 29, and the winding of magnet MM, to the alternating current generator, the said magnet MM being thereby energized and stepping wipers 14, 15 and 16 into engagement with the first set of contacts 17. 18 and 19. Upon the first step of the said wipers, oil normal switch ON assumes its alternate position and a circuit for relay R is closed through alternate contact 30, traced from ground at normal contact 26, over the previously described path, including sub-station A, returning to point 31, then through alternate contact 30 and the winding of relay R to battery. Relay R is thereupon energized, placing a direct ground upon the private contacts 11, traced from ground at alternate contact 32 of switch ON, alternate contact 33, to said multiple contact 11, thus placing a busy condition upon said contacts 11 and preventing any connector switch from connecting with the sub-station A.

Returning now to relay LR it will be remembered that magnet MM has stepped wipers-14, 15 and 16 into engagement with the first set of bank contacts, and assuming that the first set lead to a busy first selector D, there will be a ground upon private contact 17, and a locking circuit for relay LR will be established from said ground through alternate contact 34. Motor magnet MM thereupon advances the wipers another step into enlgaglement with the next set of contacts w llC are connected to selector switch D, and assuming the switch is in an idle con dition as illustrated, there will be no ground connection to its private contact 17 and the circuit of relay LR being interrupted, said relay LR deiinergizes, interrupting the circuit through motor magnet MM and preventing any further advance of wipers 14, 15 and 16. Upon deenergization of relay LR a circuit for cutofl relay CO is established from ground through alternate contact 32 of switch ON, alternate contact 88, the winding of relay CO to battery at nornial Contact- 35. Relay CO is thcreupoiieri-" from relay MRR of switch D as will-now be described. Upon the said energization of relay CO primary relay PR of first selector is energize due to the closing of alternate contacts 26 and 27 of relay CO, the energizing circuit for the said relay PR being traced from ground through the lefthand winding of relay PR, along the upper heavily marked conductor, over the line limbs and sub-staticn' A, returning over the lower heavily marked conductor and through the right-hand winding of relay PR to battery. Relay PR is thereupon energized closing a circuit through main release relay MRR, from ground through alternate contact 36, thus energizing relay MRR and establishing a locking circuit for relay R as previously stated, traced from ground through alternate contact 37, bank contact 17, wiper 14, normal contact 34, alternate contact 28, alternate contact 80 and the winding of relay R to battery. It will be noted that the main release relay MRR, being a slow acting relay, does not retract its armature when primary relay PR is rapidly operated to transmit impulses, and that the said relay MRR retainsits armature in an attracted position until the circuit for relay PR is interrupted'for a comparatively long period, which is preferably accomplished by the replacin of receiver 2 upon its switch hook. The line of sub-station A having now been extended to first selector D, the calling subscriber operates dial 7 to cause by means of contact springs 8, two interruptions of the energizing circuit of relay PR. Responsive to the said two interruptions, relay PR retracts its armature two times, thereby transmitting two impulses from ground through normal contact 36, alternate contact 35) of relay MRR, which retains its armature attracted, conductor 1, normal contact 49 to point 40 where the said im ulses divide. part of the current passing tirough primary magnet PM, and part through secondary relay SR. Responsive to these impulses, secondary relay SR is energized, closing a circuit through relay BR from ground through alternate contact 41. energizing relay BR which locks itself u through alternate contact 42 and normal contact 43 to ground, said relay SR remainin energized during the sending of the impu ses. Also respon sive to these impulses primary magnet PM is energized and decnergized' two times. thereby stepping wipers 20,21 and 22 to select the second group or row of contacts of the bank the said group of contacts being connects with second selectors in the thou- 55nd group with which the called line is associated.

Returning'now to secondary relay SR, the said relay being slow, as previously described, retains its armature in an attracted position until after the last impulse has been transmitted, when said armature is retracted and a circuit for secondary magnet SM is established from ground through normal contact 41, alternate contact A, and the winding of magnet SM to alternating current generator. The said magnet is thereupon energized, stcpping wipers 20, 21 and 22 into engagement with the first set of contacts 23, 24 and 25. Assuming these contacts lead to a busy second selector E there will be a ground upon private contact 23 and a locking circuit for relay BR will be established from the said ground through wiper 20, alternate contact 42 and the windin of said relay BR to battery, as the ofi normal switch SON has moved to its alternate vositiou upon the first secondary step of the said wipers interrupting the loo ring circuit from contact 43. busy relay BR remaining energized, magnet SM advances wipers 20, 21 and 2-2 to the second set of contacts, and assuming these contacts lead to a busy second selector E, relay BR remains energized and magnet SM steps the said wipers mto engagement with the next set of bank contacts 23, 24 and 25, which we will assume are the contacts leading to an idle second selector E. There been no ground uion private contact 23 in tiis instance, relay BR is dei nergized, interru ting the circuit for secondary magnet Ski thus preventing any further advance of wipers 20, 21 and 22. Upon deenergization of relay BR the relay 45 is energized over the circuit traced from ground through alternate contact 48 of switch SON, normal contact 46, normal contact 4?, winding of said relay 45 to battery. Responsive to the energization of relay 45 alternate contacts 4S and 49 are closed, thus extending the connection to second selector E. Also, upon energization of relay l5 alternate contact it) is closed, thereby placing a busy or ground condition upon the multiple contacts 23, thus preventing any other switch from connecting with second selector 1). This ground connection also extends through contact 50 and relay 51 to battery, energizing the said relay 51. The subscriber at sub-station A now operates the dial 7 to interrupt, by means of contact springs 8, the circuit of primary relay PR three times. the said relay PR transmitting three impulses from ground through normal con-' tact, v36, alternate contact 39, conductor P, alternate contact 49, wiper 21, contact 24, normal contact 52, to common point 53, dividing and flowing through primary magnet PM and secondary relay SR. Re-

The said sponsive to these three current impulses, relay SR is energized closing a circuit through relay BR trom ground at alternate contact 54, energizing the said relay BR. which establishes a locking circuit for itself through alternate contact and normal contact of switch SON to ground Relay SR being a slow relay retains its armature in an attracted position until after the last of the three said impulses. These three impulses also ener ize and deenergize primary magnet Pi I, which steps wi ers 56, 57 and 58 to select the third row or group of contacts of the switch, the said third row of contacts being connected with connector switches F having access to the one hundred roup in which the line of called sub-station terminates. After the last of the three said impulses has been transmitted as described, secondary relay SR retracts its armature and a circuit for secondary magnet SM is closed from ground throu 1 normal contact 54, alternate contact 62 tirough the winding of said magnet SM to alternatin current generator. The said magnet S I is tbercu )Oll energized, stepping wipers 56, 57 and 5 into engagement with the first set of contacts 59, and 61 of the selected row. If the first set of contacts lead to a busy connector switch F there will be a ground upon private contact 59 and a locking circuit will be established for busy relay BR from the said ground, the initial locking circuit for the said relay BR having been interrupted when switch SON moves to its alternate position upon the first secondary movement of wi are 56, 57 and 58. The said relay BR remaining energized, the secondary magnet SM steps the wipers into en:

gagement with the second set of bank contacts and assuming these also lead to a busy connector the secondary magnet will advance the wipers into engagement with the next set of bank contacts which we will assume are the contacts 59, 60 and 61 leadin to the idle connector switch F illustrate The said connector F being idle there will be no ground upon the private contact 59 and relay BR having its locking circuit interrupted, is deenergized, thereby openin the circuit through secondary ma net SM thus preventing any further a vance o wipers 56, 57 and 58. Upon the said docnergization of relay BR a circuit for relay (33 is established from ground through the alternate contact of switch SON, normal contact 6- normal contact 65, the winding of said relay 63 to battery, energizing the said relay and closing contact 66, thereby connecting ground to wi or 56, and the multiple contacts 50 with w iich it is connected, thus preventing any other switch'from connecting with the selected connector switch 1'. Also, upon the energization of relay 63 alternate contacts 52 and 67 are closed, thereby extending the talking conductors of the callin sub-station to the connector switch F. The ground connection from contact 66 to wiper 56 also establishes an energizing circuit for relay 67 of connector I" being traced through normal contact 6b of relay RR. Said relay 67 is energized closing alternate contact 69, but this has no etiect upon the circuit at this time. The subscriber at A now operates dial 7 to interrupt, by means of contact springs S, the circuit of primary relay PR four times, thereby transmitting four current impulses from ground at normal contact 36 over the previously described path, along the upper heavily marked conductor P, through wipers 21 and 57, normal contact 70. conductor 71, normal contact 73, tie 74, normal contact 72 and the winding of primary magnot PM to battery. The said current lilipulses divide at tie 7.4. also passing through the winding of secondary relay SR to bat tery. These said impulses energize relay SR and the said relay being slow aeting, maintains its armature in an attracted position until after the last of the four impulses have been transmitted. The said four impulses serve to operate primary magnet PM, energizing and deiiner ixing the said magnet four times, there y stepping wipers 75, 76 and 77 to select the fourth row of bank contacts. the said row including the terminals 11'. 12', 13 of the line of the called sub-station H. After the last impulse has been transmitted secondary relay SR is deencrgized releasing its armature, and a circuit for switching relay SW is established from ground through the alternate contact of switch lON, which has moved to its alternate position upon the first primary step of the wipers. normal contact 81, the winding of said relay SirV, to battery, energizing the said relay S\V which establishes a locking circuit for itself from round through contact 59 of selector E, a tomato contact 83. Upon the said energization of relay SV, contact 72 isrmoved to its alternate position, thereby disconnecting the primary magnet PM and connecting secondary magnet SM to the upper heavily marked conductor P. The calling subscriber now operates dial 7 to interrupt by means of contact springs 8. the circuit of primarv relav PR three times, thereby transmitting three impulses of current from ground at normal contact 36 along the upper heavily marked conductor to normal contact 70, the first one of the three impulses passing over normal contact 73, tie 74, dividing at this point and part of the current passing throu h alternate contact 72, normal contact 8- tie winding of secondary magnet SM and normal coutact 85 to battery and part of the current IOU passing through secondary relay SR to battery. Responsive to the first one of the three impulses, magnet SM steps the wi mm 75, 76 and 77 into engagement with the hrst set of contacts 11, 12 and 13, thereby causing the switch to move secondary otl norina contacts SON to their alternate position and interrupting the normal contact 73. The remaining impulses then flow from normal contact through alternate contact 109 and the winding of relay SR to battery, and dividing at alternate contact 109, part of the current of the im )ulscs flows to tie 7i, alternate contact 72 an then over the previously described path through magnet SM to battery, operating the said magnet two more times thereby advancing wipers 75, 76 and 77 into engagement with contacts 11. 12' and 13, which are the line terminals of the line of substation H. From the fore oing it will be seen that the first impulse o the last series flows through normal contact 73, while the rest of the inipulses flow through alternate contact 109 and then through relay SR and magnet 5M. After the last impulse, relay SR is decnergized and a circuit for relay TB is closed from ground at normal contact 86 alternate contact 86', conductor 87, normal contact 88, the upper windin of relay TR to private wiper 75. Up to t iis period, the operation of the system is the same whether connecting to an idle or a busy line, but from this point on the operation differs, depending upon whether the called line is in an idle or busy condition.

Callcrl Zine irIIc.-\Ve will assume now that the line of the called sub-station H is in an idle condition and therefore it would be in a condition as illustrated in Part 3. It will be remembered that upon the last deenergization of relav SR that a circuit was traced from ground at contact 86, through the upper windlna of relay TR to wiper 75. The line of sub-station ll being idle this ci cuit would be continued through the said wiper 75. contact 11'. and the winding of cutoff relay CO to batterv at contact 35. Responsive to the closing of this circuit the relavs TR and C0 are energized, relay CO thcrebv removing the sub-station control of line switch C. Upon energization of relav TR a locking circuit therefor is established from the said ground at contact 86. alternate contact 86'. alternate contact 89 and the lower winding of relav TR to battery at alternatc'contact 69. The closing of alternate contact 90 of relay TR places a direct ground connection from the said contact 80, upon wiper and the multiple contacts 11' thus maintaining relay CO energized an. also preventing anv other connector switch from establishing connection with the line of sub-station H. It will be noted that the closing of this contact 90 places a shunt time? around the upper winding of relav TR and therefore the said relay is maintained energized by current through its lower winding over the previously described path. Also, upon the closing of alternate contact 78 of relay TR, a circuit is established from battery through the winding of relay 91 to the gTound at normal contact 86, thus energizing said relay 91. Also, upon energization of relay TR a circuit for relay FF is established from ground through interrupter I, winding of said relav FF, alternate contact 92, normal contact 93, to battery. Due to the interruptions of the energizing circuit of relay FF by the interrupter I, the said relay attracts and retracts its armature. thereby operating springs 9,4 and 94, and alternately connecting ringing generator G and the windings of ringing control relay ROto the terminals 12' and 13' of the called sub-station H. Thus. upon each cnerg'ization of relay FF, ringing current from generator G is applied to the called line, being traced from the ungrounded pole of generator G, alternate contact 9i, wiper 7 6, terminal 12, line conductor 9', through the call bell 6' of sub-station H, returning over line conductor 10', terminals 13', wiper 77, alternate contact 94 to the grounded pole of generator G, thereby operating the said call hell 6. Upon retraction of the armature of, relav FF normal contacts 94 and 94' are closed thereby conneetinglthe windingsof ringing control relay C to the terminals of the called line. The circuit throu h the. upper winding of relay RC is trace from ground through alternate contact 95, the said upper winding, normal contact 94, to the wiper 76 and terminal 12 while the lower Winding of the said relay RC is included in a circuit traced from buttery at alternate contact 69 of relay 6?, alternate contactSQ, the said lower winding of relav RC, normal contact M to the wiper 77 and terminal 18'. Thus it will be seen thatthe windings .of relay BC are included in.,a,circu it which is interrupted by the condenserl'. and therefore while receiver 2' is on its switch-hook, relav RC does not energize and thus relay FF continues to alternatelv connect g nerator G and said relay RC in bridge of the terminals 12 and 13 of thecalled line, In response to the operation of call bell G, the called subscriber removes receiver 2' from its switch-hook, therebv interrupting the circuit through the said call bell and'establishing a circuit for direct current through impedance coil 3 and the upper contacts of switch-hook 1. Therefore. it will be seen that upon response of the called subscriber, a circuit for direct current is established through the alternate switch-hook contacts of substation H and ringing control relay RC is energized by current over the previously described path.

lliu

Responsive to theenergization of relay RC a circuit for relay 96 is established 'from ground through alternate contact 97 and the winding-of relay 96 to battery, energizing relay 96 and establishing a circuit for relav 113 from battery through alternate contact 98, the winding of said relay 113 to ground at alternate cont-act PON, relay 113 establishing a locking circuit for itselfto battery through alternate contact 93. Upon said energization of relay 113. normal contact 86 is opened, but relay RC having reviously been energized, a substitute locking circuit for relays TR and 91 is established from ground through alternate contact 99 of relay R0. The circuit through relay FF being interrupted upon the energization of relay 113 the said relay FF remains inert with its armature retracted. The relay 96 having closed alternate contacts 70 and 70' upon its encrgization, the calling sub-station A and called sub-station H are connected for conversation, the said connection extending over the heavily marked conductors having the condensers 100 and 101 interposed at first selector D. Talking current for sub-station A is supplied from battery through relay PR and talking current for sub-station H is supplied from battery through the windings of relay RC.

Release of completed co1mccti0n.-After the subscribers have finished conversatiomby replacing their receivers upon their respective switchhooks, they may release all of the switches used in establishing the connection, the calling subscriber controlling, the release of line switch C, first selector D and sec-' ond selector E, and the called subscriber controlling the release of connector switch F. Upon the subscriber at substation A replacing receircr 2 upon its switchhook, the circuit through relay PR is interrupted, deenergizing the said relay and interrupting the circuit through main release relav MRR,

r at alternate contact 36. Relay MRR thereupon rctracts its armature. closing a circuit through release relay RR from ground through switch PON, normal contact 38, the winding of relav RR to battery, energizing the said relay RR and by means of alternato contact 102 maintaining relay R of switch (1 energized, this circuit being substituted for the connection from contact 37,

which is now open. Upon energization of relay RR the circuit through relav 45 is interrupted at contact 46 allowing said relav 45 to deiinergize. Also, upon energization of relay RR, a circuit for magnet SM is established from ground through alternate contact103. normal contact 44, the winding magnet SM to alternating current generator. Responsive to current from said generator, magnet SM advances wipers 20, 21 and 22 until they reach a point beyond the last contact of the row. -When the wipers reach this position the primary retaining pawl is automatically withdrawn allowing the said wipers to be restored by spring tension from their primary adjustment. Upon the restoration of the said wipers from the primary adjustment the secondary retaining pawl is automatically withdrawn allowing the said wipers to be restored by spring tension from this secondary adjustment. Upon the restoration of the wipers from this primary adjustment. which is accomplished first, switch PON restores to normal interrupting the circuit of relay RR allowing the -said relay to deiinergize thereby interrupting the circuit through magnet SM at contact 103. It will be seen from this that while the wipers are restoring from their primary movement magnet SM might receive one or more energizations, but due to the construction of the switch this has no effect upon the restoration of the wipers. Upon restoration of the wipers from their secondary adjustment which is the last restoring movement, and upon the said wipers reaching normal, switch SON is restored.

Returning now to relay RR, upon the said deenergization of this relay, the encrgizing circuit for release relay R of switch C is interrupted upon the opening of contact 102, thus allowing the said relay R- to dcenergize and restore its contacts, interrupting the circuit through cutotl' relay CO at alternate contact 33, allowing said relay (it) to deiinergize. Also, upon dccnergization of relay R a circuit for motor magnet MM is established, traced from ground through alternate contact 32 of switch ON, normal contact 33, normal contact 29, the winding of magnet MM to alternating current generator. Magnet. MM is thereupon operated responsive to current from the said generator, stopping wipers 14, 15 and 1() forward until they have advanced one step bevond the last contact in the row, when the oil normal switch ON moves back into its nor- 1 mal position thereby interrupting the circuit through magnet MM and preventing any further advance of the wipers. Thus, it will be seen, line switch C and first selector D have been restored to normal and are available for establishing another connection.

Referring now to the release of second sclector E and returning once more to first selector 1), it will be remembered that relay 4;) was deiincrgized upon the energization of relay RR, thereby interrupting, by means of contact 4-9, the circuit of relay 51, selector E. Upon dc'nergization of relay 51. a circuit for release relay RR is established from ground at switch VON. which is closed, normal contact 105, through the winding of relay RR to battery. Relay RR is thereu on energized interrupting the circuit throng 1 relay 63 by means of contact 64 and closing an energizing circuit through magnet'SM' traced from u'ound throu h alternate contact 107, norma contact (32, t 1e winding of magnet SM to alternating current generator. The secondary magnet SM thereupon advances wipers 56, 57 and 58 to a point beyond the last set of contacts in the row, whereupon the said wipers are automatically restored by spring tension, in a manner similar to that of first selector D. The oil normal switch PON' is first restored to normal and thereafter upon restoration of the wipers to their normal resting position, the secondary switch SON is restorech Upon restoration of switch PON' the circuit through relay RR is interrupted allowing the said relay to deiinergize and interru t the circuit through secondary magnet Si The switch E having been restored to normal is available for further use in establishing other connections. During the restoration of second selector E and upon deenergization of its relay 63 the ground connection from the said switch to wiper 56 and multiple contact 59 is interrupted at contact (36 of relay (53, but the contacts 59 are maintained busy from ground at alter nate contact 86, of relay 113 of connector switch F, thus preventing any other second selector from connectin with switch F until it has been restored. *pou the subscriber at sub-station H replacing his receiver upon its switch-hook, the circuit through relay RC is interrupted at the upper contacts of the said switch hook and the said relay RC is de'energized opening its contact 99, thereby interrupting the circuit through relays TR, 91 and CO, allowing the said relays to deiinergizc, and opening its contact 97 allowing relay. 96 to delinergize. Upon deiinergization of relay 96, a circuit for release relay RR is established, from battery through normal contact 98, alternate contact 108, the winding of relav HR to ground at oil normal switch PON. Relay RR is thereupon energized allowing relay 67 to deenergize and closing alternate contacts 84 and 85 therebv establishing a circuit through magnet SM from alternating current generator G. Magnet SM thereupon advances -wipers 75. 76 and 77 to a point beyond the last set of contacts in the row, whereupon the said wipers are automatically restored by spring tension as in the case of the first and second selectors. In the restoration of the wipers, switch PON is first restored to normal and thereafter switch SON is restored to normal. Upon restoration of switch PON" the circuit through relays RR. and 113 is interrupted allowing the said re lays to deiinergize, and the deenergization of relay 113 interrupts the circuit through relav SlV. Upon restoration of switch SON which occurs after the restoration of switch PON, magnet PM is again connected through contact 73, and relay CO having been deenergized as reviously stated, connector switch F, and tie line switch 0 of substation H are available for further use in establishing other connections.

Connection -u.-z'th busy Zinc.-Having described the operation of the system in connecting with an idle line, the operation will now be described in connecting with a busy called line.

As previously stated the operation of the system until the last impulse ias been transmitted from the calling substation is similar either in connecting to the terminals of an idle or busy line, but thereafter the operation diil'ers. We will now assume that the called substation H is busy and therefore there will be a ground connection upon multiple terminal 11' from ground at switch ON if substation H be calling or if it be called the said multiple terminals 11, will be connected to ground from a connector switch as previously described. It will also be remembered that after the last impulse has been transmitted and wipers 75, 76 and 77 connected with terminal contacts 11', 12 and 13, that relays 7 and SW were locked in an energized position. After the last impulse has been transmitted as stated, relay SR" deencrgizes, closing contacts 88 and connecting ground from normal contact 86 to said contact 88. the upper winding of test relay TR to wipers 75, but as the terminals 11' are-at this time connected with a direct ground due to the busy condition of the line of substation l-l. relay TR does not energize and therefore relays 91 or FF are not energized. A characteristic busy signal is now transmitted to the calling sub-station being traced from busy back BB through the alternate contact of switch SON, normal contact 110, back along the lower heavily marked conductor, over line conductor 9, the receiver of sub-station A, returning over line conductor 10, along the upper heavily marked conductor and through the lefthand winding of relay PR to ground. The calling subscriber hearing this signal knows that the called substation is busy and therefore by replacing his receiver upon its switch book will release the switches used in establishing the connection. The release of line switch C. first selector D and second selector E is accomplished as previously described when connccting to an idle line, but the release of the connector switch is accomplished in a different manner, that is the relays are operated differently. It will be remembered that when connecting to an idle line, and upon response of the called subscriber, relay RC is energized, followed by the energization of relay 96, which in turn closed an energizing path through 113. but, when connecting to a busy line it will be remembered that none of these three reenergizes and a circuit for rela lays are energized. Therefore, relay 113 not having energized, no locking circuit for rela 67 was establishedand the said relay 6? t erefore deiinergized when the ground connection from contact 66 relay 63 of second selector E was interrupted, upon release of selector E. Therefore, relay 67 de- RR is established from battery througi normal contact 69, normal contact 108, relay RR to round at switch PON'. Relay RR is t ereupon energized, closin a circuit as before throungh secondary magnet S trace from ground through alternate contact 84, winding of magnet SM, alternate contact 85, to alternating current genorator G'. Magnet SM thereupon steps wipers 75, 76 and 77 to a point beyond the last contacts of the row and the switch is automatically restored as previously described. Off normal switches POhl and SON are restored to normal as before and the circuit through relay BR is interrupted allowing the said relay to de'e'nergize and interrupt the circuit t rough magnet SM preventing any further actuation thereof. I he connector switch I and its relays are now at. normal and said switch F is available for further use inestablishing other connections.

The system of my invention is so arranged that any switch operated in an incompleted connection may be restored by the calling subscriber. For instance, should a subscriber at A simply remove the receiver from his switch-hook and thereafter restore it without operating the dial, line switch C would connect with a first selector D energizing rela 3 PR and MRR as usual and the subscri er then replacing his receiver, relay PR would detinergize, interrupting the circuit through relay MRR which in turn would interrupt the lockin circuit for release relay R of line switch?) allowing the said switch to restore to normal. Should the subscriber at A operate the calling device a single time, thereby operating first selector D, and then replace his receiver upon its switch hook, relay PR would deenergize as before, interrupting the circuit through relay MRR which in turn would be .deinergized, closing a circuit through release relay RR thereby releasing first selector D, and upon the deenergization of relay RR resulting from the openin of off normal switch PON, line switch 6 would restore as previously described. Should the subscriber at A operate first selector D and a second selector E, and then replace his receiver upon its switch hook, first selector D and line switch C would restore and upon deenergization of relay 45 of selector. D, relay 51 of second selector E would definerize, allowing the relay RR to energize,

ereby causing the restoration of second selector E as previously described. Should a calling subscriber extend connection from his line to the line of an idle called subscriber and then replace his receiver upon its switch hook before the called subscriber has responded, line switch C, first selector D and second selector E will release as before and upon de'e'nergization of relay (33 of second selector E, relay 6? of connector switch F will deenergize, as it will be remembered that the called subscriber not having responded, relay 113 has not been energized, t ierefore no locking circuit for relay 6? was established. Upon deinergization of relay 6? relay RR is energized, thereby causing restoration of connector switch F as previously described, and it is now available for use in establishing other connections.

Where an automatic switch is used for establishin connection with an idle one of a group of trunks, it is desirable, should all trunks be busy, to transmit a signal to the calling subscriber. Accordingly I preferably connect a busy-back arrangement BB to a contact beyond the last trunk contact of each group, so that should all trunks be busy, the switch wipers will remain in connection with the contact set connected with the busy-back and the subscriber receiving this signal, replaces his receiver upon its switch-hook, thus restoring the switches operated to normal, in a. manner as previously described.

While I have illustrated and described m invention as operating in connection with a preferred form of switch structure, I do not wish to be limited to any particular type of switch, as I have contemplated using my invention witlrany switch having the necessary characteristics to co'iperate therewith. Neither do I wish to be limited to the specific circuit arrangement illustrated,as many changes and modifications of my invention may be made and I desire to cover all such changes and modifications as come within the spirit and scope of the appended claims.

I claim as my invention:

I. An automatic selector comprising a rlmary relay, a source of current, a circuit including said relay and source of current to energize said relay, means for effecting changes in said circuit whereby said relay is operated, a slow relay energized responsive to initial energization of the primary relay, and maintaining its armature attracted while said primary relay is operating, adjusting;1 elcctromagnets operated responslve to t e said operation of the primary relay, means for deiinergizing said relays, and release mechanism including one of said magnets effective upon said deenergization.

g A selector for telephone systems comprising a metallic circuit, a primary relay to 'said primary and. s e cu ent f r z n a d,

armature attracted while said armature is vibrating, electrom'agnets fOr adjusting said switch responsive to said vibrations, means for o )ening said circuit whereby said relays are deenergized, and a release relay operated responsive to deiinergization off-said slow relay whereby one ofjsaid electrorna nets is again operated to restore saidswitc i.

3. A selector for telephone systems comprising a inetalliceircuit, a primary relay and source of current for energizing sai relay in bridge of said circuit, means forrapidly .interru ting said circuit whereby said relay rapi ly vibrates its armature, a slow relay encr ized responsive to said primary relay an maintaining its armature attracted while said armature is vibrating, a frimary magnet jointly controlled by said re ays for adjusting said switch responsive to said vibraticns, a secondary magnet, means for operating said secondary magnet responsive to cessation of said vibr ation to ad ust said switch, means for o emng said circuit whereby said relays are eiinergized, a release relay'operated upon said dciinerization, and means controlled by said reease relay to again operate said secondary magnet to release said switch. v

4. Aselector for telephone systems including a wiper, primary and secondary magnets for adjusting said wiper, a meta lie cirwit, a primary relay and source of current for energizing said relay in bridge of said circuit, means for rapid y interrupting said circuit-to vibrate the armature of said relay :1 slow relay ener ized responsive to said primary relay,'an maintainingits ai' nature attracted 'while said armature is vibrating, said'primary magnet operating respcnsive to said vibrations, means for opcrating said secondary magnet responsive to cessation of said vibrations, means for deenergizing said relays and a'release circuit rendered effective upon dciinergization of the slow relay whereby said secondary magnet is operated to restore thc wiper.

5. A selector for telephone systems, in eluding a metallic circuit, a primary rela and source of current in bridge thereo means for vibrating the armature of said relay'responsive to rapid interru tions of saidcircuit,'a slow relay energize responsive to said primary relay and. maintaining its armature attracted during said vibration rimary actuating means jointly controlled y'sai relays operated'responsiveto said vibrations,fsecondary actuating means opera ted responsive toeessation of said vibration, mean sjfor opening said metallic circuit vibrates its he e yn l r l y are eiine g zedi au its-1 lease, mechanism including sa d secondary actuating means operated responsive to de; oncrgization of said slow relay.

6. A selector for telephone systems, comprising a metallic circuit, a primary relay -and source of; current. for energizing sai relay in bridge thereof, a calling device for rapidly interruting said metallic circuit, whereby said re ay vibrates its armature, a slow, relay. energized responsive to initial cnergization of said primary relay and inaintainin its armature attracted during said vibration, a primary magnet jointly ccntrolledby said relays and actuated responsive to said vibration, a secondary magnet, means effective upon cessation of, said vibration to operate said secondary magnet, means for de'nergizing said relays, and release mechanism including said secondary magnet operated responsive to said deenergization.

7. In a telephone system the combination with telephone lines, automatic switches for interchangeably connecting calling and called lines, a primary relay' in circuit with a calling line, and energized by current oven said line, means for effecting changes in said circuit for operating said relay, a slow relay ener ized responsive to initial energization u? said )riniary relay and maintained energized uring said operation, pri-. mary and secondary magnets for said switches, operated responsive to said opera-.

tion of the primary relay to extend the cirenergized by current over, said line, means contro-lledmt the sub-station of said, line for o eratmg', said relay. t'o tra nsmit current impu ses, a second relay energized responsive to said primary relay,means for maintaining the armature of'said second relay attracted while said rimary relay is op} erating primary and secondary magnets for em sw tch operatedresponsive to' said impulses, means for deiinerg'izing said relays, and a release relay effective upon said 12 deenergization to aga n operate said second; ary magnet whereby said switch is restored,

9. In a telephone system the combination with telephone lines, a' connector switch connected bya metallic circuit with a calling 1% one of said lines, a primary relay and sourceof current for energizing sa d relay in bridge ofisaid metallic circuit. a calling device" at the sub-station of said line for rund yin rn ntiag said. m ta l c ircui where.-

by said relay transmits impulses corresponding to said interruptions, a slow relay enerized responsive to initial energization of t e primary relay and maintaining its armature attracted during transmission of said impulses, primary and secondary actuating magnets for said switch operated responsive to said impulses, means controlled at said sub-station to deiinergize said relays, and means effective upon said de nergization whereb release mechanism of said switch inclu ing said secondary magnet is operated.

10. A selector comprising a pair of talking conductors, a quick acting rimary relay and source of current in bridge thereof, a slow acting relay and an energizing circuit therefor closed responsive to said rimary relay, a pair of wipers for said se ector, a primary magnet responsive to operations of the primary relay, a secondary magnet and means for actuating it responsive to cessation of operation of the primar .relay, and a release circuit includm sai secondary magnet efi'ective while sai primary and slow acting relays are restored and said wipers are off normal.

11. A telephone system comprising telephone lines, a source of current, a selector switch, means for automatically connectin a calling line with said selector switch, sai selector switch comprising a circuit including a primariy relay and source of current to ener ize sai relay, means controllable over a on ling line for effecting changes in said circuit whereby said relay is operated, a slow relay ener ized responsive to initial energiaation of tie primary rela and maintaming its armature attracte while said primary relay is o erated, adjusting electromagnets operate responsive to the said operation of the primary rela means controlled over the calling line br deenergizing said relays, and release mechanism including one of said magnets efi'ective upon said denergization.

12. A telephone system comprising tele- Cople: 0! this patent may be obtained for phone lines, a step by step switch, means for automatically extending a calling line to said switch upon removal of the receiver in initiating a call, operating magnets for said switch controlled over the calling line for extending the circuit thereof, and means controlled over the calling line by the calling subscriber for operating one of said magnets to restore the switch.

13. A telephone system comprising calling lines, line switches for said lines, a step by step switch common thereto, means for operatlng the line switch 11 on removal of the receiver in initiating a ca 1 over a calling line to extend the circuit thereof to said ste by step switch, operating ma nets for sai switch controlled by the cal mg sub scriber for extending the circuit of the calling line, and means controlled over the calling line for operating one of said magnets to restore the switch.

14. A telephone system comprising calling telephone lines, directive step by step switches common thereto, automatic line switches for automatically extending the circuit of a calling line to an idle one of said step by step switches, and driving magnets for said switch controlled over the two sides of the calling line in series for operating and releasing a selected step by ste switch.

15. In a telephone system, su scribers lines, a directive step-by-step switch provided with driving magnets, automatic means for connecting the line circuit of a calling one of said subscribers to said stepby-step switch, and means for controllin said magnets over the two sides of the cal ing line in series for o erating and releasin said connected stepy-step switch.

i ed by me at Chica 0, county of Cook and tate of Illinois, in t ie presence of two witnesses.

Gsoaoa E. MUELLER, M. R. Rocmoau.

Ive cents each, by addressing the "Commissioner 0! Patents, Washington, D. C."

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