US1257283A - Automatic telephone system. - Google Patents

Description

A H. DYSON.

AUTOMATIC TELEPHONE SYSTEM,

APPLICATION FILED AUG. I9. I90]. 7

- Patented Feb. 19, 1918.

1a suing-shin u.

A. H. DYSON.

AUTOMATIC TELEPHONE SYSTEM. Y Arrlllfianmd FILED AUG. In. 1901. 1,257,283. Patented Feb. 19,1918.

' l3 SHEETS-SHEET 2.

A. H. DYSON. AUTOMATIC TELEPHONE SYSTEM.

, APPLICATION FILED AUG. 19. 1901. 1,257,283. Patented Feb.19,1918.

l3 SHEETS-SHEET a.

A. H. DYSON.

I AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED AUG.I8,'I91- Patented Feb. 19,1918.

I3 SHEETS-SHEET 4.

A. H. DYSON.

AUTOMATIC TELEPHONE SYSTEM.

v APPLICATION FILED AUG-19,1907. 1,257,283. Patented Feb. 19, 1918.

I3 SHEETSr-SHEET 5- A. H. ovson, AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED AUG. 19, \901- Patented Feb.19,1918.

3 SHEETS-SHEET 6.

i A. HQDYSON. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED AUG. 19. 1907- 12573283. v Patented Feb. 19,1918.

l3 SHEETS-SHEET 7.

mwl Q ZW 'A. H. DYSUN.

AUTOMATIC TELEPHONE SYSTEM.

, APPLICATION FILE D AUG.19. 190T- Patented Feb.19,1918.

I 3 SHEETS-SHEET 8- A. H. DYSON.

AUTOMATIC TELEPHONE 'sYsTEMi I APPLICATION HLED AUG. 19. I907. I

1,257,283. Patented Feb. 19,1918.

finatmm A. H. DYSON.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION men AUG. I9. 1901.

1,257,283. Patented Feb. 19.1918.

13 SHEET$SHEET I0.

.mm f m m. N \k IE 0 7 mm 1 M; FR d n on P A. H. DYSON.

AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED AUG. I9. I90].

Patented Feb. 19, 1918.

I3 SHEETS-SHEET I2.

' A. H. DYSON.

AUTOMATIC TELEPHONE SYSTEM.

A'FPLIICATION FILED AHG.I9. 1901.

Patented Feb. 19, 1918;

13 SHEETS-SHEET I3,

UNITED STATES.

PATENT OFFICE.

ALFRED H. DYSON, OF CHICAGO, ILLINOIS, ASSIGNOB, BY MESNE ASSIGNMENTS, TO KELLOGG SWITCHBOARD & SUPPLY COMPANY, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Febr19, 1918.

Application filed August 19, 1907. Serial- No. 389,180.

To all whom it may concern Be it known that I, ALFRED H. Dyson,

, a citizen of the United States, residing at one hundred first selectors and the wipers Ohica 'o, in the county of Cook and State of-Il'hnois, have invented new and useful Improvements in Automatic Telephone Systeiiis, of which the following is a specification.

The present invention relates to automatic telephone systems generally, and has to do more particularly with that type which the well known selector and connector switches of the two dimension type of the art are employed in conjunction with similarly constructed line selectors controlled by master switches. In such systems the movable contacts, or wipers, of the two dimension switch are associated with a large number of fixed, or passive, contacts arranged in a bank and the wipersare first given a movement in one direction followed by-a movement at an angle thereto, the former, or primary, movement. bring'ing the wipers to a desired group of bank contacts and the latter, or secondary,- movement causing the wipers to engage desired bank contacts in' the selected group. The connections among the different switches will be best understood by discussing a. par ticular case. Thus if one hundred point switchesbe employed in a ten thousand line exchange system arranged on a basis of ten per cent. trunking, there would be one hundred master-switches, one thousand line selectors, one thousand first. selectors, one thousand second selectors, and one thousand connectors; each subscribers line would be multipled to ten line selectors and ten connectors; the line selectors and first selectors would be united in pairs without multiplmg; the wipers of the second sel'ectors would be multipled tothe banlccontacts of of each connector would be nuiltipled to the bank contacts of one hundred second selectors. Obviously with different assumptions, values differing f1'om -tl1e above would be used, but this specific example will suflice to indicate the character of the system .to which my invention belongs.

In systems of this character heretofore proposed, the construction of the switches and the associated circuits have been such that the proper operation of the system was possible only by the employment of more or less complicated mechanism. For

example, it is common in such'systems to have certain contacts thrown to one position upon the first movement of the switch wipers and then restored upon the operation of a release magnet. This results in moreor less complication of parts. Other similar features might be pointed out but this example will suflice to shOW the character of the com= plications referred to.

One of the principal objects of the present invention is to devise a system of the character indicated which s'li'all be free of these I objections. This is preferably accomplished by the use of simple switches, having simple driving and release mechanism, combined.

with a novel arrangement of circuits in which ordinary relays-are employed to bring about the desired results.

Another object of the invention is to extend this simplification of structures to all commercial adaptations of the straight automatic system so as to include trunking between exchange, nickel-in-the-slot service, measured service, party line service of different kinds, as well as unlimited service.

Still another object of the invention is to devise a novel arrangement of electrical connections between the switches'whereby the chances of the calling line finding an idle trunkthrough which to extend its circuits are greatly increased.

The invention also includes other feat/1111135 and details which, together with the above, will be more fully understood .u on reference to the following detailed escript ion taken in connection with the accompanying I Referring to the drawings, Figure.- 1,

which is the principal figure and includes parts 1, 2 and 3, illustrates diagrammatically an automatic telephone system embodying certain features of the present invention; Fig. 2 illustrates a trunkin circuit provided with a repeater and designed to connect exchanges located at some disof a number of trunks running' to a given private exchange, or to a roup of telehones having a single ca ling numberfii iigs. 5', 6 and 7 illustrate connector circuits designed foruse with party lines, the latter illustrating in addition a four-party subscribers line; Fig. 8 illustrates a modified slot service substation and line circuit; Fig. 9 illustrates a novel method of interconnecting and trunking between switches by which the chances of a cal-ling party obtaining a desired connection are increased; Pigs. 10-,11 and 12 are elevationsof a line selector viewed from different Sides, the switch bein also typical'of the other selec tors and t e connectors *en'iployed in the system; Fig; 13is a plan view of said switch; Fig. 14 is a sectional plan of a portion of the same taken on a plane indicated by the line l i -14L of Fig. 11; Fig. 15--i'a detail "iew of certain connector off-normal contacts; Fi s. 16 and 17 are front and side eleyations o a n1aster-switeh en'iployed in the control of theline selectors; Figs. I8 and 19 are front and sectional elevaticms, respectively, of a ringing machineeniployed in con nection vith certain of the party line clrcults; Flgs. 20. and 21 are. front and rear elevations, respectively, of meter mechanism employed for nleasured service; amlFigs.

and 23 are front and side elevations respecpartyln ie use.

Mai/L system. Apparatus,

Referring to the drawing, and more particularly for the present to Fig. l, which may be considered the main diagram, M at the left oi' tlio diagram designates a subscribcrs station provided, with fslofi equipment and united to the main exchange by the line limbs l'f andH which ttrll'li'l'ltlll. in multiple contacts of line connectorsnnd line selectors. At the opposite end of the dia gram, N dcsignatcsa subscriber-s equipment which is not c signed for slot s1 twice and which is si1nilarly unitedv by line Qliinbs l-S' to the exchange andihc line limbs are similarly.connected toitl1e ,lllillll l'llclt'mk lacts of connectorsand lin'e selectors. lonuection. is obtained between the line at the left and the line at the'right through the agency of a master-switch (),a line selector Q, a first selector U, a second select-or- V aud" a connector. \V. Assuming that. the sclecto rs and connectors employed in. establishing this connectionare provided with one lulnd'rei'l bank' contten thousand lines in the exchange arranged on a basis of ten per cent, trunking, then, the

Throughout-these views like characters refer to like parts.

I with the thousalulgroup-to which the c and assliuningthat there are number of switches and their multiple zirrangement heretofore outlined will exist. In such case there would be one-hundredni terfswitches 0. one thousand line selectors Q, one thousand first selectors U, one thousand second selectors V and one thousand connectors V. The subscribers lines would be dis rided into groups of one hundred, and ten line'selecting switches would be assigned to each group, thu enabling each line to be multiplcd to the corresponding bank eon tacts on ten dill'erenf line selectors. Each group of line selectors would be under the. control of one masterswiteh, having-a pair: of bank contacts assigned to each lineselee; tor. Each subscribers line would'also niultipled to "the corresponding bank contacts of ten connectors. In the diagram, only two of the ten sets of multiple contacts of the line selectors and cornice-tors are-illus tratcd, while but five pairs of bank eon. facts of the master-switch are slniwn. The I movable contacts, or 1 wipcrsg of each line selecting switch Q. are tied to the corresponding' wipers of a first selector ll, thus prov 9o riding onc'thousand dilccl connections"be tween the one thousand line selectors and the one thousand first selectors. The wipers of the second selectors are multiply connect- 1 ed to the bank contacts of" the-first selectorsand'since' there area thousand oteaehof these switches, the wipers of each-second sclector' are connected to, the corrcsponding.v contacts 0t one hundred firstselech'n's. S'i1n-,.

sets an idle line selector Q, in operation to aulon'iatuzally seek out. and establish wa ncction with his line, thus extend ngthe calling line circuit to the first selector EU. paired with the actii'atcd line selector Q.'-.]L5yr The calling party thenyby mounsof his call in; mechanism, transrriits a number. of. ini pulses corresponding; to the 'digits '0' lunlnnbcr ol the subscriber a.nte(l.. 'llhr st series of these impulses opcratcsjlu; corn/12b, ;v

ncctcd first selector so aslomauscit to pick out an idlesocoiul selector associated l lcd line belongs. Thug if the number of theeall-g ing party were two thousan l fiolne odd, the 1:25

first set of two impulses would JlLo-V wipers of the first selector group of its bank, contacts and wouh I automatically more the wipers o\ "cr,the'con;- tacts in this bankuntil an idle eont a t i i i Eli:

ilarl \",'thc wipers/of each of the thousandLlQD lhrough the agency of the master-switch 0-, lie

encountered, thereby extending the circuit of the calling party to an idle second selector in the second thousand group. The sec ond series of impulses would similarly operate the second selector V to pick out and es tablish connection with a connector associated with the hundreds group to which the called line belongs. Thus if three impulses were transmitted over the circuit, the second selector V would move its wipers to the third group of its bank contacts and the wipers wouldthen-automatically move overthe contacts in this bank until an idle one was selected, thereby extending the circuit of the calling line to a connector having access to the called line. The third series of impulses would cause the connector to move its wipers to that group of ten contacts in which the contacts of the called line were included, and the final series of impulses would cause the Wipers to move over the contacts in this roup until thecontacts corresponding to t e called line were encountered, thus completing the connection between the calling and the called lines.

Each line is provided at the exchange with a line relay LR which is instrumental in closing a circuit through the masterswitch 0 upon the initiation of acall, and a'cut-ofi relay G0 which is used to destroy the normal substation control of the line relay and to otherwise vary the line connections.

The master-switch 0 comprises a pair of wipers 20-21 cooperating with bank contacts 22-23 and caused to step over said contacts by a motor magnet MM the comlete operation being controlled b the-reays 2%25, as hereinafter'more fu ly pointed out.-

The line selector includes the wipers 26, 27, 28 and 29 cooperating with bank contacts 30, 31, 32, 33 and, where the meter mechanism X is used, with an additional wiper 34 cooperating with bank contacts 35 as. willappear from Figs. 9 to 13 inclusive, described more fully hereinafter.

'26, 27, 28 and Y34 partake of the two movements of the switch, that is, the primary and secondary movements, while wiper 29 Wipers partakes only: of the primary movement.

The primary movement of the wi ers is brought about by primary magnet P COD- ' trolled by a primary, relay PR, and its secondary movements is similarly brought about-by a secondary'magnet SM controlled by a secondary relay SR, while the release of theswitch, which permits it to return to 1ts normal position, is brought about by a release magnet RM controlled by a release relay RR. The switch is also provided with primary and secondary oil-normal contacts-- PO and SO which are operated respectiveily:

. upon thei first primary and the first secon {try movements of the switch. Although contacts of two connectors;

The first selector ,U includes the wipers 39, 40, 41 which cooperate with bank con tacts 42, 43, 44 in response to the operation of the primary Ina net PM, controlled by the pllnltiI/P' relay R, and the secondary magnet S controlled by the secondary relays SR and SR'.- The wipers in this case all partake of the primary and secondary movements and the switch is released through the operation of the release magnet RM and the release relayRR'. The pri mary off-normal contacts PO and secondary off-normal contacts SO here, as before, are operated upon the first primary and secondary movements of the wipers respectively. The circuit associated with this selector also includes a reversing relay RV for reversing the direction of current supplied to the calling line and an associated relay 45, all of which will be more fully understood from the subsequent descriptlon.

The second selector-V comprises wipers 46, 47, 48 which cooperate with bank con tacts 49, 50, 51 in the same manner as the first selector U. In this case, the corresponding relay, magnets and off-normal contacts are designated by corresponding reference characters having the exponent 2- instead-of 1.

The connector W is provided with wiperswith-a busy relay BR, a ringing relay RG,

a control relay R, a tip relay .TR, a flip- In addi-' flop relay FF, and a closing relay OR,

all of which cooperate in the manner heremafter more fully set forth. 7

a As in the case of the line PS, the line P-S is provided with a cut-off relay CO and a line relay LR.

In this fi are I have also illustrated mechanism or recording the completed connection over each calling line. One of these meehanisms is associated with each linezselector and comprises 'a printi ng magnet 58, a .type wheel 59, actuated by a motor magnet MM controlled by relays 60,

(it and wiper 62 rotated with the type wheel Jiland cooperating:with banlr 'contacts 63 of whichthere'cisxa number equal'to. the nun'iber; ot-contaets 35011 the line selectors.

The .equipn rcnt at substation i\'["inc1udes the usual-switchhook 64s, receiver 65, callbell 456,41 nsmitter -67, calling mechanism tiS and sot mechanism 69 including a. polarized relay 70. The equipment at substation; differs from that at substation M by olnittii'ig the"slot mechanism (3!),

Obviously, the various subscribers lines enter-int "the exchai'ige will be distributed through the agency of a distributing board which Iylunte indicated at the points desig 11ated-y.D-B. Many di-tl'erel'tt methods of distributingmaybe employed, but I preferably distribute: the line limbs and :the'

hook tit and.thereby. establishes a circuit which maybe tl'fltttltl l hfilll the live, or negatire, pole of the battery llthrougrh rcsistzincc Tl, clostal contact T6 of outwit relay (.70, line limb S, closed contact. 75. the windin; of. lock, controlling magnet 74, switchhook til. transmitter (3?, closed contact 73,

line limb l, Iiormalconlaet 72 of cut-off re lay (It), normal et-sntact; 77 of line relay LR, and the winding ol said. relay to the ground.- ed; or return side of the battery. The resulting nloy ement ot' the bent act 77 toits alternate position closes-a new energizing circuit for the line rel ay LR which may be traced from the live, or negative, pole of the battery JV-tlnrongh the winding of relay 24. of the.1nastrr switcl1 0, closed Contact T8 of t-nt otl' relay (0 and alternate contact 77 0'' li no relay Lift through the winding of said relay to grount-l. The closing of this circuit continues the energization of the l ne relay and actuatesrelay 12 t .so as to close itscontact it) to, omplete a starting circuit for one of the line selectorsQ, as will he hereinafter eaplainedf ,The movement oi contact 80. of 11111 30-30." this g through normal contae corresponding t ,o the calling line; ;1d ,eoimection. normally ,xisting 91 0f. out et? relay elay .LRJr emovcs the non mal groiu d coi'mection from therontact-s CO and normal contact 80 of line relay LR. in addition to the removal of this ground 'n'hich establishes that condition which will cause the line selector wipers to stop in engagement with the contacts of the line aller they have been moved to the desired group, the actuated contact 80 of the line relay, grounds the winding of relay 82, which, upon being energized, opens its contact 83 to remove the normal ground from those contacts 3333, etc., whichteorrespend to the group of contacts in which those of the calling line are located, thereby establishing that condition which will cause the line selector to stop its primary movement at the proper group of bank contacts. The contact 84: of the line relayupon"being attracted, destroys the normal battery con nection through the winding of the cut-oft" relay GO to the contacts 36-36, etc, of the connectors to which the line P'S is connected, and substitutes a ground. connec-- tion therefor. As will be hereinafter explained, the normal. battery connection to these contacts permits connectiorrto be made to the line PS as a called line, While the ground connection renders the said line busy to lIl-COIIIlIlg calls.

The mastenswitch wipers 2021 are brought, after each operation of a line sc lector Q, into engagement with contacts 22-23 assigned to an' idle'line' selector as will be hereinafter explained- -Thus, as soon as relay 24 is energized, a starting circuit for silch line. selector is completed by the closing-of battery B through the winding of primary relayPR, primary'offnormal contact 85, contacts 22-20, closed contact 79, andnormal contact 86 to ground,

thus energizing primary relayPR to actnate its contacts and thereby complete a cir cuit' from the. live pole of the alternating current generator 87 through the winding of primary magnet PM and alternate con tact S8 of primary relay IRto ground,'thus causing the wipers 26, 27,. 28, 29 and 34 to more in a. primary direction. The said group relay 82 has its Winding connected to a plurality of alternate contactsSO,

indicated by the symbol (which sign serves throughout the drawing to indicatd a. common connecting point), on as :many different line relays LR. Thus,1in thee x ample-chosen, there would be one hundred line relays and ten group relaysfor a grou p of one hundred calling lines. Each group of the switch wipers, the initial energizing f circuit of the primary relay PR is inter-- rupted, but in the meantime the closing of,

contact 89 of said relay has completed a new path through wiper 29 which is maintained circu t at all times except when an ungrounded contact 38 is engaged. It should also be noted that although the wiper 29 is normally out of engagement with contact 33, it engages said contact at the time the primary off-normal contact 85 breaks, thus insuring a suitable circuit for the relay PR until the wipers have been moved to that group of bank contacts which included the contacts assigned to the calling line. Just as soon as this group of contacts is reached, the primary movement of the switch wipers will be discontinued and the contacts 88-89 of relay PR will return to normal. The return of contact 88 will immediately energize the secondary relay SR over a circuit extending from the live pole of battery B through the winding of said relay, a secondary off-normal contact'90, primary cit-normal contact 91, which is closed at this time, and closed contact 88 to ground. The movement of contact 92. of relay SR to its alternate position, will at once close an 81161: gizing circuit for the secondary magnet bM extending from the live pole of the alternating current generator ,93 through the winding of the secondary magnet, alternate contact 92, and normal contact 94 of wipers will continue until amungrounded contact. S ncethe contact release relay RR to ground. The resulting repeated energizations and dcenergizations of the'seeondary magnet Will cause the switch wipers 26, 27, 28 and 34; to move in a secondary direction over the contacts 30, 31, 32 and 35, respectively, of that group of bank contacts including the contacts of the calling line. Since upon the first secondary movement the contacts of the secondary off-normal switch S0 are actuated, the initial energizing circuit of'jthe relay SR will be interrupted but in the meantime the closing of its contact 95 will provide a new path through normal contact 96 of release magnet RM to wiper 26, and

thence 'to ground so long as said wiper engages a grounded contaet 30.; It W1l1 be noted in this case as in t e case ofwiB 29 that the end of the wiper is prefera madebroad enough to bridge the space be tween contiguous contacts and that although normally out of engagement with the nearest bank contact, it will engage said contact by the time the secondary off-normal contacts are moved from normal the secondary movement of the switch ment.

bridges and thereby energize relays Thus,

wiper 26 engages.

30 corresponding to the calling line has been wipers will be stopped in engagement with the contacts corresponding to said line. Since other subscribers lines are multiply connected to contacts over which the wipers 27-28 pass during this secondary movement, and since conversation may be going on over a connection including said contacts, the relay SR is arranged to electrically disconnect the wipers 27-28 from other parts during this secondary move- This is brought about by contacts 96- 97,' which in their normal positions, join the adjacent portions of the strands or conductors LL', but when actuated, separate them, thusdisconnecting the said wipers from other parts. Thus, as soon as the wiper 26 engages an ungrounded contact 30, the relay SR is deenergized and the contacts 92, 95, 96, 97, return to-their normal positions thereby discontinuing the further secondary-movements of the wipers and restoring the normal connections of the wipers 27-28. The contacts 9697 of relay SR when in their alternate positions connect the right-hand portions of the strands LL by a bridge which includes alternate contact 96, closed'contact 98 of release relay RR and alternate contact 97. The same portions of the strands L-L are united by a bridge including normal contacts 99-400 of reverse relay RV, windings of primary and secondary relays PR and SR and batteries bb. These batteries being Y arranged in series, supply current over a circuit including both of these PR and SR to actuate their contacts. This prevents the possible closing of the release circuit (when the secondary off-normal contacts SO .are actuated) from battery 13 through the winding of release relay RR, closed contactlOl, contacts l02103,of relays PR and SR and the winding of release relay RR of the first selector U to ground.

Thdrestoration of the contact 92 to nor- I mal, since the .contact 104 of the secondary off-normal switch S0 is now closed, imme diatelycompletes-a circuit which" is instrumental in causing the movement of the master-switch O :to engage contacts of an idle line selector. This circuit extends from ground at contact 94 of release relay RR through said normal cont-act 92, closed contact-104, contacts "2321 of the master- Due to the mechanical relation of the parts,

the energization and deenergization of this n'iagnet will step the wipers 2021 into engagement with the/ next pair of bank contacts.

' this pair is in use, there exists a ground at one point or another, as will be explained, on the corresponding contact 23 wluch Wlll maintain the relay energized and thereby maintain the circuit for the motor magnet. As soon, however, as an ungrounded contact 23 1s encountered, thisenergizlng circuit for relay 25 will be interrupted. Contact 23 corresponding to a busy line selcctor will always be grounded, while that corresponding to an idle line selector will .be ungrounded, thus insuring the stopping ofthe master-switch with its wipers in engagement with contacts eorrespoiuhng to an idle lmesclector. the ground connection with, the contact 23 may exist over the path just traced including contacts 104, 9'2, 91, or by Way of alternate contact 96, alternate contact a") closed contact no closed contact 91 and'alternate contact be to ground. ()r the said ground may be maintained through the off-normal contact 136 ot the primary oil-normal switch P0 of the first selector U, or at other times through closed contact vi .178 of the reversing relay RV and closed contact 1740f relay 45.

;As soon as the secondary relay SR of the line sclector has been deiinergized, and the 1 adjacent portions of the conducting strands L-,L united, there are at once established circuits for the primary and secondary rclays P11 and SR 111 l eu ot that previously traced through the alternate contacts 9(3'-9T "of relay SR. Thus a circuit extends from i the, live, or negative, pole of battery B ,tl-irouglrthe winding of the cut-off relay G0,

contact 10t3-107 of said relay, bank contacts 31, wiper 27, strand L, normal contact 99 of reversing relay RV, winding of primary .relay PR to the live, or positive, pole of grounded battery I). At the same time, a circuit is completed from the ive, or negative, pole of battery I) through tl1ewiud-' in g of secondary relay SR, normal contact I100 .of reversing relay RV, strand L ineluding contact 97, wiper 28, contact 32, line lianb- 13, via normal contact 7t; and coil 71 .to the negative pole of battery ll prior to the operation of cut-oft relay Ct) and immediatelysubscqneirt thereto, over line. limb S, contact 75, lock magnet. 74, SW]t.-Cl1-llOOl (it,

,.transmitter(l7, contact 73, line limb l, in-

orll-ulingalternate contact 7:3 of cut-oil relay tt), contact 31., wiper 27, l nk strand L, in rlrulillg contact tlti. normal contact 99 ot re rel-sing relay RV, the winding of pril-nary .relayfllli' to tluyposith e pole of battery I). flho cl sing of these cu'clnts maintains the relays lli-ijllltlhbli' energized, and in addi- ,tion: energizes the cut-otl' relay t) and the lock eontrollio g,.Iuagnet 74 associated with the calling line. 'The movementot contact If the line selector corresponding to i 72 of the cut-Ofi' relay to its alternate posi tion continues line limb P to contacts 31 -31 and interrupts the initial energizing circuit of the line relay LR and thus destroys the normal substation control of said relay. The opening of its contact 78 likewise interrupts the circuit established through relay Bat of the master-switch and the line relay. The opening of contact 76 interrupts the normal connection of batteryB' to the line limb S. Thesubscribers circuit is thus completed over the heavily marked lines to the sections of the strands LLlying beyond the condensers l08-109. The movement of contact 81 interrupts the path for current over the strand L through the cut-off role) 00, but before said circuit is interrupted, a new circuit is provided for the cut-elf relay CO, which extends from lmt'tery B through the winding of cut-oft relay, contacts 107,81, engaged contact 30, wiper 26, normal contacts 96 and 95, and winding of relay 61 of the meter mechanism X, to ground. Thus the cut-oil relay (0 is maintained energized. The guarding circuit to ground for the line selector con.

tacts 30, 30, etc, and for the connector con, tacts 3G, 36, etc.. is now furnished through said relay 61 as follows :fro :1 contacts 36 via normal contact 84, alternate contact 81 and'said contacts 30, 30, etc., and thence to ground through said relay (51 over the circuit p'rcriously traced for holding the cutoll'relay (It) energized. Upon closing this circuit the meter mechanism X is set in operation to move its wiper 62 and the rigidly connected type wheel 59 to that position corresponding to the calling line P c. This is brought about by the energization of relay (31, which completes a circuit for the motor magnet MM extending from the live pole of the alternating current generator 109 through the winding of said motor magnet, closed Contact 110 of relay (l1 and closed contact. 111 of relay 60 to ground.

The wiper (S2 is thus moved over the bank contacts 63 which are'eqHaI in number to the line selector bank contacts 35. These contacts are preferably arranged in a circle so that the wiper (32 need hare but a simple rotary motion. Corresponding contacts 35 and 63 are electrically connected and since wipers 3i and 26 are connected. there exists at this time a potential at the contact (33 'correspoluling to the calling line. which will be above that of ground and. consequently, as soon as wiper G2 in its more-- uleut engages this contact 63,11 circuit will be completed from contact (33, through wiper (i2, \\'iudiug of relay tit) and closed contact (51' of relay (it to ground. \rhereby relay (i0 will be energized and its contact '1l1 opened to thereby interrupt the circuit of the motor magnet MM and thus discoutinue further movement of the wiper. By

' zation of said line relay I lease of relay 24 of the master-switch 0 unmeans of contact 61', the ground connection with wiper.62, and thence to contacts 63, 35 and 30 of the particular switch in use, is removed upon the release of theswitch and subsequent improper operation, due to'the presence of such a ground, is thereby prevented. From this it will be seen that the wiper 62 and the type wheel 59 are moved to a definite position corresponding to that of the calling line and left in that position. As will appear more fully hereinafter, as soon as the desired connection with the line PS is'complete, the printing magnet 58 will be energized and there will be placed on a recording sheet, a type impression corresponding to the calling line, as for example, the number of the calling line. The disconnection, and consequent deenergization, of line relay LR causes the release of the group relay 82 unless there be another line relay, belonging to the same sub-group of ten, energized at this time for the purpose of also initiating. a'call. Assuming no such condition to exist, the releaseof relay 82 will restore the ground via contact 83 to bank contact 33 and to the other multiple contacts on the nine other line selectors,

thereby permitting wipers 29 of said other line selectors to rotate past the sub-group containing the calling line Whose call has now been picked up. Also the denergi- LR causes the re less "there be at that time another line relay belonging to the same group of one hundred subscribers then initiating a call. Assuming there be no such other call existing, the release of such relay 24 will prevent the starting of another line selector when the master-switch steps its wipers 20-21 around to engage the bank contacts corresponding to the next idle line selector.

With the parts in this position, then it remains for the calling party to operate his calling mechanism 68' to send the necessary impulses to extend his circuit to that. of the called line. The calling mechanism is diaranunatically represented by a disk having a number of teeth adapted to engageasprmg 73' to cause to break contact upon the return of the disk due to return spring 112,

and a single tooth similarly cooperating with contact spring 75 to cause it to open its contact after the contact 78 has completed its interruptions. The disk is also with a pin which engages a spring contact 113 to hold it out of engagement with a similar spring contact 114 and a grounded contact 115.

locked by means of a hook 116 arranged to en 'age a notch in the disk and normally.

held in engaging position by a spring and move out of engaging position by the ener: gizations of the magnet 74. In operation, the disk-11s moved against the tension of the the diagram,

The disk is normally.

manner as substation N, that is without theslot mechanism 69, the callin party would now be free to operate his dlal to. send the necessary impulses. In the present instance, however, any break which might be made by contact 73 would be bridged by normal contact 116' of the slot mechanism so that there would be no resulting interruption of the line limb P as would be necessary to cause the operation of the connected first selector; consequently it is necessary forthe calling party to deposit a nickel or other token in the slot of the slot mechanism 69. When thisis done, the contact 116 is forced by the tzoken to its alternate position. This is accomplished in the present instance by having a suitable projection from the con tact 116 extend into the slot'. .As indicated upon the lower portion of the substation dia gram, the pivoted end of the switch-hook is provided with an upward projection 117 which engages the lower end of a pivoted arm 118 which is adapted to be moved in the slot in order to determine the disposalrelay 70, which in normal position bears against a fixed stop. In case the connection is completed, the polarized relay is energized by a reversal of current, caused by the operation of the reversing relay. RV,'to throw the upper end of the arm 118 to the left to collect the token by allowing it to pass downward through the right-hand outlet of the slot, into a suitable receptacle. In case the desired connection is not completed, the token is returned upon the restoration of the receiver to its hook which forces the arm 118 to the right to the position indicated in thereby allowing the token to pass out of the left-hand outlet of the slot into a suitable holder. from which it may be taken by the calling party.

Assuming now that the calling party has deposited his token and thereby interrupted a bridge about the contact 73, he will be at allow it to return to its normal position-andhe will follow this operation by similar operations :in'whichhc will rotate the dial suifibring three teeth below the con-

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