US1601053A - Telephone system - Google Patents

Description

Sept. 28 1926.- 1501;053-

. 5 B. WILLIAMS I TELEPHONE SYSTEM Original Filed e 1924 8 Sheets-Sheet 2w Sept. 28, 1926. 1,601,053

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' 5 B. WILLIAMS TELEPHONE SYSTEM 1 original Filed June 27. 1924 v 5h t -$he t 8 lm emort Ja/m/e/ A [MW/arm Any . Patented Sept. 28, 1925.

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SAMUEL 13. WILLIAMS, 0F BROOKLYN, NEW YORK, ASSIGITGR TO .UE STERN ELECTRIC COMPANY, INCURPGRATED, OF NEX -1' YORK, Y., A COREORATION OF NEW YORK.

TELEPHONE sYs'rEM.

Application filed June 27, 1924, Serial No. 722,631. Renewed April 5, 1926.

This invention relates to telephone systems, and moreespecially to systems of this 0 iaracter which utilize automatic switching equipment for the establishment of conversationalconnections. 2

in systems employing common controlling mechanisms located at the central office and serving to govern'and control the selective operation of the automatic switches, it frequently happens that one of these mechanisms encounters trouble while in the eXer- It is, therefore, the object of. this inven- 7 tion to release a disabled controlling mechanism without defeating the connection which is undergoing extension and to thereupon take in use either the same or another mechanism for another trial.

' controlling a selective switch together with means for disconnecting the marker from the sender if such marker fails to function, without disturbing the connection undergoing extension, and to connect said sender to one of said markers for a retrial.

A further feature relates to means for preventing the sender from reconnecting to any marker which has encountered trouble and been released. 2

Referring tothe drawing, Figs. 1 to 8, inclusive. when taken in the order illustrated in 9, disclose a portion of a telephone exchange system embodying the features of this invention.

Fig. 1 shows schematically a subsc-ribers line, a line" switch, a trunk outgoing there-- from, a sender selectorrswit'ch, and a portion of a subscribers register; sender. Fig. 2 shows a district selector switch in which terminate the trunks leading from the Fig. 4 shows a multi-contact relay connecting device for associating the senders with the markers. 1'

F igs. 5, 6 and 7 illustrate one of a number of controlling markers, the function of which is to determine the selective and testing operation of the selective switches such as the one shown in Fig. 2. l

8 shows a frame connectorfor conne'cting the markers to the frames of the switches shown in Fig. 2 and also'a'trunk connector for associating the marker with the different groups of trunks outgoing from the selector switches.

The system disclosed herein is an improvement upon the type of system illustrated and described inthe patent of S. B. lVilliams, 1,517,331, Dec-2, 1924:, to Whichreference is hereby made for an understanding of the various operations which may hereinafter be referred to but not specifically described General descflptz'mt 0f the apparatus and opcmzfion.

The callingsubscribers lines, such as'the line 100, terminate-in vertical rows of con tacts in coordinate line switches 101. These switches 'have'access to groups of trunks, such as the trunk 102, which extend and appear in vertical rows of contacts in district selector switches. The trunk 102, for exanr ple, appears in the vertical row 201 of the selector-200. Another trunk 21 1- sin'iilarly occurs in the vertical row of contacts 202 and still other trunks maybe provided.

Thedistrict selector switch 200 contains. a number of vertical rows of contacts 203, 20 1, etc., in which appear numerical groups of trunks outgoing to succeeding switches.

The switches'101,108.200, etc., are of the coordinate type comprising a plurality of intermediate or horizontal links, "together with vertical andhorizontal selecting'and operating bars and individual magnets for operating these bars. The district selector 200, for instance, has a number of links 205, 206', 207 208, etc., with individual operating bars 215,216. 217 and 218 and the respective horizontal operatingmagnets 219, 220, 221 and 222. Furthermore, the switch has. vertical selecting bars 209, 225, 213,, etc., to; gether" with corresponding operating magnets 210, 211 and 212.

l tit? r The trunks 102 leading from .the line switches to the district selector also appeal. l

in the rider selector switches 108. These selector switches have access to a number of recording senders, one of which is partially shown in Fig". land in Fig. 1.

The register senders have an appearance in the sender connecting devices 100, each diiterent sender being represented by a ditt'erent niul'ti-contactrelay -103, .04, etc. The device s'lOO is-also provided with anun'iber of relays Z10, $12, etc., each of which represents' a diil'erent one of the controlling marlters. By operating the proper pair of these relays, any sender may be connected to any marker.

The marker includes a number of registers 500, 501 and which receive the otlice portion of the entire designation, made up of three separate digits, from the register sender. Furthermore, a translating de vice 500 .is comprised of a number of sets of multi-contactrelays 510, 511, 512, etc, and 518, 514, 515, etc. and relays 507, 508 and 509. The registers cooperate with this translating device in such a manner as to determine the selection of the group relays 612, 613, 614:, 615, etc. These group relays determine the particular groups of trunks outgoing from the selector switches, which must he invo red to route tie call in the direction corresponding to the designation transn'iitted to the sender.

The marker also determines the selection and operation of the proper one of the trains connectors 800 in order to associate itself with the n'roup of district trainee 200 containing the frame in which appears the trunl: over which the connection has been extended tromthe calling line. This frame connector 800 includes a number of relays S02 and 803. each individual to a different one of a plurality of markers. it also includes a number of multi-contact relays st and 805, each individual to a particular district trams 200 in the group. Relay 805. for instance, is individual to the particular trams 200 shown in the drawing.

The trunk connector 801 comprises a numher of relays 810 and 811 each individ ual to a ditferentn'iarker. he connector 801. in addition includes a number ot' relays 812 and 813 each of which is individual to a dii'l'erent group of trunks outgoing from the district frames 200. The trunks ot each group may be multiplied to appear in as many selectorswitc-hes as may be desired.

The marker is'equipped with a testing de vice consisting ott-a number of sets oi testinc relays 2'00. These relays serve to test the horizontal links and the correspondino outgoing trunks of any group. i i? Anothe1*fu-nction ot' the marker is to terinine trointhe. ollice code registration which it receives from a sender. the nature or class otthe connection-that is to beer;- tended;

This" it does through'the medium.

of a translator 506 and may cause the operation of one of a number of class relays 528. These class relays, or the translator itself, may directly cause the closure of circuits extending' back into the sender tor the operation of the proper class relays therein, thusgiving the sender the necessary intorniation to enable it to prepare to exercise the necessary control over the connection involved.

T he line switch 101 and selector switches 200 and 108 may he of the general construction and operation as the one shown and described in the patent of C. L. Goodrum and J. N. Reynolds, No. 1,515,735, Nov. 16, .1924.

Detailed description of tile establishment of a connection.

It will now beassumed for the purpose describing the invention, that the subscriher of line wishes to obtain a connection extendingthrough the district selector s itch 200. The calling subscriber in initiating the call, causes the operation of line switch 101 to extend his line over an idle trunl; 102 to the district switch 200. The "initiation of the call also causes the operation of sender selector switch 108' to associate thetrunk 102 with the idle register senocr shown in the drawing. During the operation of the sender selector-switch 108, a Clltliltls'('OlIlPlQtQt tor operating the relay 10 -l. The relay 10-1 completes a hold ing circuit for the slow-release relay 100 which has been previously operated. This holding circuit leads through the lower contact 0t relay 10st and the contact of relay 106. As soon as the sender selector switch 108 and the line switch 101 have operated, the suhv'icrih rs line included in series with the impulse relay 300 in the sender. The circuit o this purpose may be traced from batter through'the right winding of relay 300, outer right contact ot relay 310, thence through the sender selector switch 108, over the ring of the trunk 102, through the line switch 101, over the loop of the line 100, and returning through the'line switch 101 and the sender selector 108, inner right. contact of relay 310, to ground through the right winding" the balancing coil S03. lay 300 operates and closes the circuit for the slow-release holding relay 301. Relay 301 completesoperating circuitstor the re lays 302 and 316. These relays lock in circalls from battery, through theirwindines. thence through the inner right contact et relay 3091,1038] contact-0t the relay 310, to ground at the inner left contact of relay (.32. Relay 30?. applies ground potential through K391111161 lettcontact, left hacltcontact ot' relay 310, to the conductor-3l lwhich ssrres to hold the sender selector switch 108 and the relay 10% in operated condition,-

Recording thedesz'gncton in the sendcax- Thesubscriber now manipulates his dial (not shown) to transmit a number of impulse. representing the Wanted designation. The impulse relay 300 responds to these impulses and cooperates with relays 305, 306, 30?, 303 and 309 and with a set of counting relays diagrammatically illustrated by the rectangle 304, to cause the setting 03": a corresponding number of registers illustrated diagrammatically by the rectangle 109. The general manner in which the toregoi o; op-

erations may be accomplished. is dewibed and illustrated in the patent above mentioned to S. B. \Villiams, No. 1,517,331, Dec. 2, 1924.

Association of the sender with an idle markevt+As soon as the first three of registers 109 have been operated, a circuit is closed extending over conductor 318, through the Winding of relay 313, to battery. Relay 313 operates and causes the operation of relay401 to initiate the actuation of the connector 400. The circuit for this purpose may be traced from battery. through the lower contact of relay 402, left winding; of relay 401, conductor 413, contact of relay 311, outer right back contact of relay i, left contact of relay 313, conductor. 320, conductor 321, to ground at the contact of relay 316. Relay 401-operates and closes a holding circuit from battery, through the Winding of relay402, right contact and Winding of relay 401, to ground over the circuit above traced. Relay 401 holds and relay 402 operates in this latter circuit. Relay 402 in operating, prevents the operation subsequently of another relay similar to the relay 401., With the relay 401 operated, niulti-contact relay 403 is energized in a circuit from. battery, through its Winding, left contactof relay 401', inner contact of relay 405, to gIO11I1Cl-;%1ti1e inner lower contact Fm Stirs v of relay 402. Relay 403 locks through its inner contact to ground at the upper con tact of relay 402. Relay-402 completes a start circuit to select the first idle' one of the markers. Assuming that the marker appearing in the multi-contact'relay 412 is busy, and that the next marker illustrated is idle, this start circuit leads from ground, through the inner lower contact of relay 402, lower contactot relay 405, left front contact of relay 406, left back contact of relay 407,.left back contact of relay 408, left winding of relay409, to battery at the outer contact of ,relay411. Relay 409 operates lay 409, conductori414, to ground at the inner lower contact of relay 402. Relay 409 locksuand relay-411 operates .in this circuit.

Relay .411 causes the operation of relay. 408

inan;1obvi0us. circuit to identify the assoas above traced. Relay 600 looks throt.

contact of relay the connector 400 over conductors 416, 41

ciate-d marker as busy. Moreover, relay 411 causes the operation of the inulticontact relay 410 in a circuit from battery, through the Winding of the latter relay, middle right contact of relay 409, to ground at the inner contact of relay 411.. With the relay 403 and 410 operated, the register sender is connected through the connecting device 400 to the marker shown in 5, 6 and 7.

' As soon as, the connector 400 operates, the relay 600 in the marker is energized, in a circuit from battery, through the winding of said relay. conductor 618, through the connector 400, to ground over conductor 413 511 its inner right contact, outer ri ht back contact of relay 607, oute right 'contactot re lay 606, to ground at the inner left back It Will be assumed that the connection be ing extended is one involvinga local line as a called line. Accordingly, the operation of relay 600 upon the seizure ot the marker, causes theoperation of the relay 711. The

circuit for this purpose leads from battery,

through the Winding of relay .711, inner right back contact or" relay 710, conductor 622, inner right back contact of relay 606, to ground at the inner left contact of relay 600. p

The record established on the registers 109 of tie sender is now transferred to the corresponding registers 500, 501 and 5020i the marker. The registers 500, 501, and 502 are made up of the relays 516 to 527, inch".- sive, eachrcgister comprising four of these relays. Thesender registers 109gare1nadc up of corresponding relays which are operated in different combinations in response to the subscribers dial.

lit will be assumed that the designation is such-that the third relay the egistor of the sender, the first a d second relays of the second register, and the second relay of the third register of sender, are operated. Accordingly, the corresponding relays 518, 520, 521 and 525 of the marker registers 500, 501 and 502 are energized. The circuit tor operating these, re lays extends from -round, through the inner left contact or relay 600, inne'rright back contact ot relay 606, outer ight contact of relay 608, left contact of relay 604, conductor 619, thence through the connector 400, conductor 111, thence through the front contacts of the opearted register lays 109 in the sender and returning through i 413 and 419, through the windings of relays 518, 520, 521 and525, respectively, to but tery. The remaining re gn-1 r relays ofthe registers 500, 501 and 502 are also temperarily energized by means of a circuit which may be traced from grounded conductor 619. thence over conductor 530, through t no -nor= I nal contact of relay 504, right back contact of relay 503, conductor 415, through the connector 100, and thence through the back contacts of the register relays 109 which have failed to operate and returning through the connector 400 over the corr spending conductors to the windings of relays 516, 517, 519, 522, 523, 52 1, and 527, to battery. hen all the marker register relays hay operated, a circuit is closed for operating re lay 503, which may be traced from batt U through the winding thereof, thence in series through the con'acts of the operated re ter relays to ground over conductor 550 as previously traced. Relay S locks through its inner right front contact and the normal contact of relay 50% to the grounded conductor 530. Relay503 at its right back cont opens'the o 'ierating circuits of the marker register relays which do not correspond to the operated relays in the sender, per-mitt these relays to release. The relay 503 a closes an obvious circuit for relay 501, wh operates and locks through its own conta to the grounded conductor 53/. Relay 50%;- in turn opens the holding circuit of re 503, permitting this latter relay to role;

F or an understanding of the manner in which the marker register relays (17G operated and released as above described, reference is made to the application of O. From, Serial No. 690,707,iiled Febrraiy 1924:.

Operation of the translator and selection of the proper trunk g'r0up.The reg. 500, 501 and 502 having been set, the tra lator 506 is now operated to prepare a cir cuit for selecting one of the group relays shown in the upper part of Fig. 6 to identify the proper group of trunks to be employed in entendiug the connection through the district elector switch 200. lVith the relay 518 of the register 500 operated, a circuit is closed for operating the relay 50?, traceable from battery, through the wind- 111g of the latter relay, inner lower back contact of relay 519, inner lower front contact of relay 518, inner lower ack contacts of relays 517 and 516, conductor 532, left contact of relay 50st, to the grounded conductor 530. Since the register relay 525 is operated, a circuit is closed for operating niultieontact relay 515 as follows: battery, through the winding of relay 515, inner lower trout contact of relay 525, inner lower back contact of relay 52a, to ground over conductor 82. Since the rela s 520 and 521 of register 501 are operated, a circuit is completed 101' operating the niulti-contact relay 512 and may be traced from battery, through the Winding of the latter relay, through the distributing fame 533, contacts of relay 515, lower front contacts of relays 521 and 520, lower back contact of relay 523, to the grounded conductor 532. The group relay 612 is now operated in a'circuit from battery, through the winding of this relay, distributing frame 620, conductor 621, tl rough the distributing frame 5341, contact of relay 512, lower contact of relay 507, conductor 535, to ground at the outer left contact of relay 60S, Relay 612 represents the group of trunks appearing in the veitical row 20% of the distri *t selector switch 200.

Operation of the district f'rrmte connec- Z 07r1 kt the time relay 50% operates, it closes an energizing circuit for relay 801' of the frame connector 800. This circuit may be traced from battery, through the outer right contact of relay 60st, conductor 623, winding of relay 607 conductor 819, outer right contact of relay 50-1, conductor 540, through the connector 100, conductor 110, right back contact of relay 322, conductor 523, thence oi'er conductor 111, through connector 100, to ground over conductor 619 as previously raced. lielay S07 completes a circuit for 'elay 806 from battery, through the right ding of the latter relay, front contact of y 807, back contact of relay 820, assumthis relay to be deenergized, upper conrelay 809, to ground at the back conslow-release relay 808. When relay S06 is operated, it operates slow-release relay 808 in a circuit from battery, through the winding of relay 808, lower back contact of relay 809, right contact of relay 806, conductor S21, outer left contact of relay 611, middle right contactof relay 607, outer right contact of relay 608, conductor 622, inner right back contact of relay 606, to ground at the inner left contact of relay 600. The relay 808 operates and opens the operating circuit of relay 806. Relay 806 being slightly slow to release, however, remains energized until relay 808 has fully operated. The holding circuit for relay 806 is then closed from battery, through the left contact of relay 806, left back contact of relay S23, winding of relay 809, to ground at the front contact of relay 808. Relay 809' operates and opens the circuit of relay 808. Relay 808 releases and operates the multi contact relay 802. The circuit for this purpose leads from battery, through the wind ing of relay 802, outer left contact of relay 806, upper front contact of relay 809, to ground at the back contact of relay S. Relay 809 being operated, prevents the operation of another of the relays 806 and 823, thereby avoiding interference by other markers. After relay S08 releases, relays 806 and 809 remain operated in acircuit which leads through the lower front contact of relay 809. right contact of relay 806, to the grounded conductor 821.

The vertical operating magnet 210 0011- trollingthe row of contacts 201 in the switch 200. in which appears trunk 102, is now operated. The circuit may be traced frombatl L 'ict t of tery, through the winding of said magnet, conductor .227, left back contact of relay 107, through the switch 108, conductor 112, con nector 400, conductor 421, normal contact of relay 603, inner left back contact of relay 610, conductor 627 through contacts of the frame. connector 800, to the grounded conductor 821. The magnet 210 rotates the vertical bar 209 and prepares all contacts in the row 201. Magnet 210 extends the grounded conductor 227 through its inner lower contact, over conductor 228, through the winding of the multi-contact relay 805, to battery. Relay 805, which is individual to the switch 200, operates and results in the connection of the conductors from the markers through to the frame of the, selector switch 200.

With the frame connector 800 operated, relay 608m the marker is energized in a circuit from battery, through the winding of said relay, outer left back contact of relay 61.0, conductor 680, through the connector 800, to the grounded conductor 821., Relay 603 at its normal contact opens the circuit of magnet 210,but before this occurs said relay closes a substitute holding circuit for said magnet and also for relay 805. The holding circuits be traced from battery, through the winding and contact of magnet 210, conductor 228, and in parallel from battery, through the winding and contact of relay 805, contact of relay 802, conductor 824. make contact of relay 603, inner left back contact .of relay 610, to ground over conductor 627 as previously traced.

i The vertical magnet 210 operates the horizontal magnet 226 which rotates the associated bar and prepares the special horizon tal link 224. The relay 107 in the trunk 102 is now operated in a circuit from battery, through its winding, conductor 113, through contacts of the link 224, conductor 229, tlnroughthe connector 800, conductor 826, conductor 825, left contact of relay 603, to round at the left back contact of relay 608. Relay 107 operates and at its left back contact opens the original energizing circuit of magnet 210. 7

Operation of the distinct trim-k o0nne0t0r.- Duringthe foregoing operations, the district trunk connector 801 is also being operated for he purpose of connecting the test relays 7 00 with the proper group of trunks outgoing from the district selector 200. For starting the trunk connector 801-in operation, the relay 815 is energized in a circuit from bait-cry. through the winding of said relay, duct-or 827 through the distributing '1' me 620, outer left contact of group relay 612, conductor 628, middle left contact of relay 806, to ground at the back contact of relay 808. Relay 815 operates the relay 814 in a circuit from battery, through the left winding of relay 814, front contact of relay 815, back contact of relay 828, upper back contact of relay 817, to ground at the back contact of slow-release relay 816. Relay 814 when operated, causes the operation of relay 816 in a circuit from battery, through the .winding of the latter relay, lower back concircuit ofrelay 816, which subsequently releases. After relay 816 releases, the relays 814 and: 817 are held energized in a circuit is: lingthrough the lowerfrontcontact of reiay .817, left contact of relay 814, to the grounded conductor 821. The multi-contact relay 810'is now operated in a circuit from battery, through its winding, outer right contact of relay 814, upper front contact of relay 817, to ground at the back contact of relay 816. I The inulti-contact relay 812,

which is individual to the group of trunks appearing in the vertical row 204 of the distr t selector 200, is operated in a circuit from battery, through its winding, conductoi 880, contact ofrelay 612, conductor 681, middle right contact of relay 814, to ground at the back contact of relay 816.

Testing Zia/cs audit-miles at the district selector swch.The I marker is now pre pared to proceed witha test of the selected group of trunks outgoing from the district selector 200 and also the corresponding horizontal links. The rightwindings of the double wound test relays 701, 702, 703, etc., serve to test the trunks 280, 281, 282, etc., in order. The left windings of these relays serve to test the corresponding horizontal links 205, 206, 207, etc. The test circuit for the trunk 230 may be traced from battery, through the right winding of relay 701, next to the inner back contact of relay 708, right backcontact' of relay 706, conductor 714, through the trunk connector 801, conductor 831, to the sleeve conductor of the trunk 230. 'lhe'test circuit for the corresponding link 205 may be traced from battery, through the left winding ofrelay 701, inner back contact of relay 708, conductor 715, through the frame connector 800, conductor286, tothe test connector of the link 205. In a similar manner the test circuits for the remaining trunks of thegroup and of the correspond ing links may be traced through the windings of the test relays 800.

It will be assumed that the trunk 232 is the first trunk in the group which is idle lil simultaneously with the idle condition of its associated llIl 207. Since each of the preceding trunks or each of the corresponding preceding horizontal links is busy, or both trunk and link are busy in each instance, the corresponding test relays 701, 702, etc., are operated either. by the energization of one or of both windings. Since, however, the trunk L32 and its associated link 207 are both idle, the test relay 708 remains deenergized. The operated relays 701 and 702 lock in circuits through their right windings and contacts, conductor 717, inner right contact of relay 608, to the grounded conductor 622.

At the instant the testing operation commneces, a circuit is completed for operating the vertical magnet 212 of the district selector 200. This magnet requires an appreciable interval in which to become fully operated and consequently serves to measure the time in which the relays 800 are re quired to test the links and trunks and to assume their operated and non-operated c011- .ditions accordingly. The circuit for magnet 212 may be traced from battery, through the winding thereof, conductor 237, through the connector 800, conductor 832, contact of relay 612, conductor 629, through the trunk connector 801 to the grounded conductor 821. lVhen magnet 212 is operated, it causes the energization of relay 60 1 in a circuit from battery, through the winding of relay 60%, normal contact of said relay, conductor 682, through the frame connector 800, conductor 238, to ground at the contact of magnet 212. The relay 604 locks through its inner right contact and the inner left contact of relay 608 to the grounded conductor 622.

The relays 708 and 709 are now operated in circuits from battery, through their windings, thence over conductor 718, inner-right contact of relay 604, to ground over conductor 717 as above traced. Relays 708 and 709 disconnect the test relays 700 to prevent their subsequent operation. The relay 728 relating to the idle trunk 232 and link 207 is now operated in circuit from battery, through the winding of relay 712, Winding of relay 728, left back contact of test relay 703, left front contacts of preceding energized test relays 702, 701, etc., conductor 721. through the trunk connector 801. conductor 83 1, normal contacts of relay 605, contact of relay 607, thence to ground over conductor 718 as previously traced. Relay 712 also operated in this circuit.

Relay 712operates the relay 314 in the sender in a circuit from battery, through the winding of relay 314-, conductor 324, connector 400, conductor 420, conductor 636. inn-er right contact of relay 711, to ground at the contact of relay 712. Relay 314'locks through its left contact to the grounded conductor 320. Relay'31 l at its outer right back contact opens the original operating circuit of the relay 600. Relay 600, however, remains energized in the locking circuit previously traced,

The horizontal magnet 221 is next operated by means of a circuit from battery, through the right winding of said magnet,

conductor 239, connector 800, conductor 8.3:), middle left contact of relay 728, to ground over conductor 717. Another circuit for magnet 221 may be traced from battery, through both windings thereof, thence over conductor 234, through the connector 800, conductor 836, next to the outer front contact of relay 708, inner left contact of relay 728, to the grounded conductor 717. The closure of this latter circuit also results in placing a ground potential upon the test conductor of the horizontal link 207. Magnet 221rotates the bar 217and effects connection from the trunk 102 through the link 207 to the selected idle trunk 2232.

Returning to the point where relay 60loperates, it may be noted that this relay causes the release of the translator and marker register relays. Relay 604 at its left contact removed ground potential. from conductor 619, causing the release of relay 50-1 and consequently the release of relays 507, 512 and Relay 604 at its back contact opens the circuit of relay 807. When the translator releases, the group relay 612 is deenergized.

Release of the district frame (and firm/a connectors and 0f the wmflcen-The marker has completed its function in operating switch 200 and should now be released in order that it may be taken into use in connection with other calls. At the time the district selector switch 200 operates to extend the trunk 102 through to the trunk 282,. a circuit is closed for operating the release relay 607. This circuit may be traced from battery, through the winding of said relay, conductor 635, right front contact of relay 728, conductor 730, conductor 7 3 through the trunk connector 801, conductor 840, thence through the district selector switch 200, sleeve conductor 115 of the trunk 102, to ground at the contact of slow-release relay 106. Relay 607 locks through its inner right contact; inner right contact of the relay 608, to the grounded conductor 622.

It may be noted at this time that the horizontal operating magnet 221 is also locked in a circuit from battery, through both its windings. thence through contacts of the switch 200, to the grounded sleeve conductor 115, Therefore, this magnet will remain operated after the marker. which furnishes the operating circuit therefor. becomes released.

Relay 607 opens the holding circuit of relay 600 and this latter relay becomes re leased. Relay 600 removes ground potential vertical magnets 210 and 212 are from conductor 717, causing the release or" all operated testrelays. Relay 607 in op erating, removes ground potential from conductor 821 causing the release of the frame connector 800, trunk connector 801 and all operated'relays associated therewith. The

also released and the connection through the switch 200 is now held by the continued operation of the horizontal magnet 221. Relays 603 and 604 are also deenergized.

At the time the relay 314 is operated in the sender, the original holding circuit of the relay L01 associated with the connector 400 is released. The relay 401, however, r mains operated in a circuit which may be traced over conductor are, conductor 116, thence through the connector 400, conductor contact of relay 606, to ground at the inner left contact of relay 602. When relay 607 subsequently operates as just explained, the holding circuit of relaysl02 and 401 is also opened. These relays release, in turn causing the release of the connector 400 and all energized relays associated therewith. Thus the marker has been completely released and disassociated from the selector switch 200 and from the sender.

Release 0; the sen(Ze'/*.From this point on, the connection may proceed in any suitable manner according to the class of the call concerned. Afterthe sender has completed its function, a circuit may be com-- pleted for the release relay 310. Relay 81C opens the holdingcircuit of the impulse relay 800 which releases the slow relay 301. Relay30l in turn releases the holding relays 302 and 316. These relays move ground potential from the holding conductors to permit the release of the various energized relays in the sender.

The sender in releasing, also causes the release of the sender selector switch 108 above mentioned patent of S. B. lh illiams,

1,517,331, Dec. 2, 1924.

The marker encounters tr0ubZe.-If at any time following the seizure of the marker for the purpose of controlling the extension of a connection the marker encounters trouble, as for instance the failure of a relay to operate or for any other reason, the marker will cease its no *mal progress with the re sult that the selector switch cannot be operated. To prevent the connection which has been successfully extended to a partial completion from failing on account of such an occurrence, it is desirable to discharge the marlrer which has thus become disabled and to immediately seize eitherthe same or To accomplish these desirable ends, the

system is so arranged that if the marker encounters trouble after its seizure and a given interval of time, normally sufiicient to permit the complete operation of the marker, expires, said marker will be immediatelv discharged. After the discharge of the disabled marker, the sender immediately zes a marker, which may be either the same or newunarker according to the busy and idle condition of all markers available. After the re-seizure of another marker, a new attempt is made to operate the switch to extend the connection.

At the instant themarker is seized, the re lay 600 operates as previously explained. As soon thereafter as the constantly operating interrupter 637 completes its upper contact, the relay 601 operates as follows:

battery, through the winding of relay 601,

normal contact of said relay, outer left con-- tact. of relay 600, to ground at the upper contact of interrupter 637. Following the closure of the upuer contact of the interrupter. an interval of time expires before the closure of the lower contact which is sufficient to permit the marker, if acting normally, to complete the exercise of its function. If, however, the marker finds trouble and refusesto proceed, the interrupter 63'? on final ly closing its lower contact causes the operation of time measuring relay 602. The circuit may be traced from battery, through the winding of said relay, right contact of re lay 601, to ground at the lower contact of interrupter 637. Relay 602 closes an obvious circuit for the lamp 638, which illuminates to notify the attendant that the mall;-

er is in trouble. The relay 602, which is slow to release, ten'iporarily locks in a circuit from battery, through its winding and inner right contact, normal contact of key 639, to ground at the outer right contact of relay 600. Relay 602 at its inner left back contact opens the locking ci cuit of the relay 600. Relay 600, however, still remains energized under control of the sender. Relay 602 furthermore, causes the operation of relay 811 in the sender by means of a circuit from battery, through the winding of said relay, conductor 325, connector 400, conductor 4:22, out-er right contact of relay .602,

with the first idle marlzer.

to ground at the outer right contact of relay 60d Slow-release relay 311 operates and severs the operating circuit oi relay 600. Relay 00 thereupon releases and brings about the release of the marker from the sender 1n the manner hereinbeiore described. Relay (500 also opens the circuit of relay 602. All relays in the marker which have 1 een operated, are released. Also the frame connector and trunk connectors 800 and 801 are restored to normal, provided their operation has been either started or completed. I

Since the key 639 is in its normal position as shown in the drawing, the marker will immediately 'e restored to common use and may again be seized either by the sender shown or by other senders, as though no trouble had happened.

As soon following the di.:cha: marrer the slow relay 31. circuithereinbelore traced pleted tor relay 600. a vice e00 is actuated to re- The first idic n'ia'rlrer may hang en to be the same one which was previously used or it may be any ot the otherniarkersi lhillowingth association of the sender with the marl d, the i.-

reeistcrs 109 is transferred to t marker registers. the translator is operated, and the ophrat-ions hereinbctore described proceed in a second attempt to control the CllStlJJt s elector switch 200 to extend the trunk 102. it no trouble is encountered by the marker this time, the connection proceeds and the switch 200 is successfully operated. r-lowcver, it trouble is again encountered for one reason or another and the time measuring device in the marker counts a predetermined interva then the marker is discharged and another attempt is made.

This procedure will continue until the sender has succeeded in associating itselt with a'marlzer which is capable of fully completing its functions.

It the attendant notes that any particular marlzer is show' signs of trouble frequent- 1y, he i'nay throw he key 639 to its actuated position. The result ot throwing the key (339 is to so modify the circuits of the marker that when the inarl cr is subsequently discharged on account oi? trouble condition, it will be indefinitely held out of service and cannot be select d by a sender. "Recalling the point in the operation where the relay 602 actuates at the end the time interval, it will be noted that this relay now locks permanently to ground through the key 639.

Relay ($02 in its operated condition, closes a holding circuit for the relay e08 associated with the connector This latter circuit may be traced from battery, through the right winding of relay 4108, conductor 424, to ground at the outer leit contact of relay 602. The relay 408 renders the marker non-selectable by extending the start wire through to the next relay beyond corresponding to the next marker in order.

After the marker has been investigated and the cause of the trouble remedied, it may be restored to service oy rel asing the key 639.

hat is claimed is:

1. In a telephone system, a selective switch. means for extending a connection to said switch, a controlling mechanism, means for seizing said mechanism for use, said mechanism arranged to progress through a sequence of operations for governing the se ective operation of said switch to further e: .end said connection, means for rcleasing said mechanism it it fails to tuction nor1nal ly without releasing said connection, and

means tor causing the reseizure of said mechanism in a repeated attempt to go'vern the operation of said switch.

' ln telephone system, a selective switch, means for extending talking connection to said switch, a controlling mechanism, means for seizing said mechanism, leans for connecting said mechanism to the switch. said mechanism arranged to progress t 1 a sequence ot operations for controll n the selective operation of said switch t .urt icr extend the connection, means fordi.connecting said mechanism from the switch and for rendering the mechanism available for reseizure it it fails to function normally without releasing said connection, and means for causing the reseizure of said niechanisn'i immediately in a second attempt to control the operation of said switch.

3. in a telephone system, a selective switch, means for extending a connection to said switch, a register senoer. a controlling mechanism, means for connecting said sender to said mechanism, means in saic sender for variably setting said mechanism, said mechanism arranged to control he se lective operation of said switch to further extend said connection. means for releasing said mechanism from the sender when such mechanism fails to function normally with out disturbing the e ended connection, and means for causing s d sender to reseize said mechanism in a further attenpt to control the selective operation of said switch.

d. In a telephone system, a selective switch, means for ez'itending a connec'ion to said switch, a marker for controlling the selective operation of said switch, means for seizing said ma her for use, a time measur ing device for releasing said marker it it fails to function properly after its seizure without disturbing th extended connection, and means for causing the reseizure of said marker in a turther attempt to control the operation of said switch to further extend said connection.

5. In a telephone system, an automatic,

I suflicientto allowthe marker, if functioning normally, to control said switch, means effective at the end of the interval when the marker encounters trouble for releasing said marker without disturbing the extended connection, and means for causing the reseizure of said marker in a further atv tempt to control the operation of said switch.

6. In a telephone system a selective switch, means for extending a connection thereto, a plurality of markers each arranged to selectively control the operation of said switch, means for seizing one of said markers for use, 'means for releasing the seized marker if it fails to function normally without releasing the extended connec tion, and means for thereupon causing the seizureof anyone of said markers'in a further attempt to control the operation of said switch.

7. In a. telephone system, a selective switch, means for extending a connection to said switch,;a plurality of markers each arranged to selectively operate said switch to further extend said connection, means for seizing an idle one of said markers for use, in a time measuring device for releasing the the selective operation of said switch to further extend the connection, means for connecting one of said senders to an idle one of said markers, means controlled by the sender for setting the marker, means for releasingthe connected marker if it fails to progress normally in its operation, and means for thereupon connecting the sender to anyone of said markers, depending upon the busy or idle condition of such marker, in a repeated attempt to control the operation of said switch.

9. In a telephone system, a selective switch, a plurality of markers eacharranged to selectively operate said switch, means for seizing the first idle marker for use, means for releasing the seized marker if it fails to function normally, means for rendering the released marker non-selectable,fand means for thereuponseizing an idle one of the reoperate said switch.

10. In a telephone system, a selective switch, .a plurality of markers each arranged to selectively control the operation ,ofsaid switch, means for seizing an idle one of said markers for use, means for releasing the seized marker if it fails to progress normally with its functions, means for thereupon seizing one of said markers in a repeated attempt to control the operation of said switch, and .manual means for determining whether a marker which has been maining markers in a repeated attempt to released on account of trouble shall be withmeans for taking 'said mechanism into use,

said mechanism arranged/to govern the se lective operation of said switch to further extend said connection, means for releasing said mechanism without releasing said connection, and means for again taking said mechanism into use in'a repeated attempt to govern the operation of said switch.

.12. In a telephone system, a selective switch, means for extending a connection to said switch,a plurality of controlling mechanisms each arranged to selectively operate said switch, means for seizing an idle one of saidmechanism for'use, means for releasing the seized mechanism without releasing said connection, and means'for again seizing one of said mechanisms in a repeated attempt to selectively operatesaid switch.

In witness whereof, I hereuntosubscribe SAMUEL B. WILLIAMS.

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