US1594898A - Telephone system - Google Patents

Description

BEST AVNLABLE com Aug. 3 1926. 1,594,898

G. R. EATON TELEPHONE SYSTEM 7 SSheets-Sheet 1 Filed Dec. 18, 1922 Fig.4. Fm.6.

INVENTOR. GEORGE R.EATON I ATTCRNEY ,ABLE C BEST AVA Aug. 31926; 1,594,898 G. R. EATON TELEPHONE SYSTEIM Filed Dec. 18, 1922 e Shets-Sheet 2 mvsmfoR- 520x512 12; EATON. BY

ATTORHEY BEST AVAILABLE com Aug. 3 1926. G. R. EATON TELEPHONE SYSTEM 6' Sheets-Sheet Filed Dec. 18. 1922 INVENTOR GEORGE R EATON 3 WW ATTORNEY BEST AVAlLABLE 00m Aug. 3 1926. 1,594,898v

G. R. EATON l TELEPHONE 5mm Ii 226K297 ig}? D90- 13, 9 6 -Sheets-Sheet 4 GEORGE. EATON ATTORNEY BEST AVNLABLE com Aug. 3,1926.

(5. R. EATON TELEPHONE SYSTEM 'Fi1ed Dec. 18, 1922 6 Sheets-Sheet ,5

J m Y J J R m E 6 WE m J 9 N E O m a 3 W n I .r, m R E Y A ..G B M a 5 \3 )la 5 2 1 2 H. m fih mp 5 5 m k Nvv L ummw VI.) T. F w IIVIIIIL r and J30 s z 9 I 7 M 5 1 Z Z w V1 1 a \llnlL 5 i T 4 z MWWWM 2 2 m BEST AVAILABLE COP\ Aug. 3 1926. 1,594,898

' G. R. EATON TELEPHONE SYSTEM Filed Dec. 18, 1922 6 sheets-Sheet 6 FIG.6.-

MVENTQR GEORGE EATON BY f U ATTORNEY Patented Aug; 3,' 1926.

BEST AVAILABLE COPY UNITED STATES PATENT oFFrc-E.

enonon' n EATON, or OAK PARK, mLrnoIs; ASSIGNOB T KELLOGG swrrcnnoean AND SUPPLY COMPANY; or CHICAGO, rumors, a coarom'rron or rumors.

TELEPHONE SYSTEM.

Application filed December 18, 1922. Serial in. 607,513. a

My invention relates to telephone systems and has to do morerparticularly with common battery type systems in which the cord circuit used for interconnecting subscribers lines are of the feature type comprising inv stantaneous' disconnect, secret service and automatic rmgmgfland an ob ect of my 1n-' vention is the provision'of an improved circultv arrangement for a system of the above 1 type.

One of the features of my. invention-is theprov'ision of a telephone system in which 'f'thc subscribers of an exchange system are divided into groups and terminate at the exchange in -a group of finder switches as callinglinesand multiple jacks as called lines common to th'e'gro'up of lines, and to which said lines are multipled'so that when I a call is-initiated, one of the finder, switches of the group is caused to" operate to seize the-contacts of the calling line.

Another feature of 'my-invention is the provision ofcall distributing means in' which a group of tinder switches have multiply connected thereto cords terminating at the difi'erent operators positions at the exchange switchboard, so that a group of subscribers lines may, through the agency of this group offinder sw'itches have access'to a plurality of operators positions so that the instant a subscriber initiates a call, he will be con neted to any one of the plurality of operators: at" the exchange board.

Another feature of my invention isthe elimination of the answering jacks of the subscribers lines terminating at the exchange board, the "-said lines being only equipped withn'iultiple jacks, thus permitting the lines per section to be materially 4 increased.

Another feature of my invention is the means for controlling the busy indication at the operators position. Each osition remains busy as long as its parti'cu ar operator has'a greater number of calls before her .than' any other adjacent operators. Means arealso provided for removing the busy indication whenever an operator has a smaller load, or a load equal to the smallest load on any operators position.

A feature of this busy controllin means is the distribution of the calls to t to. operators according to their respective abilities -to handle calls.

Still another feature of my invention is a scribers, and which comprises" provision whereby as many as four calls may be stored at an operators posit on in such a way that a distributing means 15 provided for'calls in such a manner as to give each operator. the same number of stored calls, 00

in case theoperators are not keeping up with the load. This storing-feature provides a definite means for'checking up the speed at which the calls are being handled at any particular positionne For a more complete understanding of my invention, referencerlmay be had to the ac- 'comp'anying drawings, in;which1;I illustrate apparatus for interconnecting 'two sub- V l l 3" 4, 5 and '6, which, when joined as shown in Fig. ,7, illustrate a complete connection; a

, Referring now more. 1n eneral to my inf vention as illustrated, in' ig.'-1 I show a calling substation A terminating at the ex-- change in a line circuit'L comprising a line relay LR, out-off relay CO and multiple jacks J; The line finder switch FS of'my invention comprises a rotary magnet RM' which automatically operates when .a' call is initiated by the subscriber at the substation A' to step the wipers 13, '14, 15 and 16over the bank contacts 17, 18, 19 and 20 to select the contacts of the calling line. A common starting wire SW is provided and is common to a group of subscribers, lines which lead to a group of switches FS. A bridging relay BG is provided which energizes when the calling 'line is seized by the switch FS to shunt the rotary magnet RM to prevent further advancement of the wipers 13, 14, 15 and 16. The switchin relay. SH energizes upon the actuation of'tl ie relay BG to extend vthe starting conductor SW through to the next finder switch FS of the group (not shown).- .The switch FS is also provided with a battery feed relay-BF and a release magnet REL, which when energized brings about the restoration of the switch wipers 13, 14, .15 and 16. A set of ofi-normal contacis ON are provided which assume their alternate ,pos'itionon the first step of the switch off normal and remain so until the switch FS is again restored to normal;

' A 1mm of finder switches FS" are also associated with the group of calling lines and are similar to the switch-F8 and are provided with a springaestored shaft which carries wipers 75, 76, 77 and 78 and contact sets 79, 80, 81 and 82, of which there are U0 fifty sets, which may be engaged by the wipers 75, 76, 77 and 78, and to which contacts the cord circuit 6 of the exchange are multipled'. A rotary magnet RM" is provided which steps the wipers 75, 76, 77 and 78 from one set of contacts 7 9, 80, 81 and 82 to the next to seek an idle cord circuit. it

F S, and'terminates in the exchange board in a calling plug-C1. The cord C is provided with a'relay 101 which is energized when the cord'is seizedby a finder switch FS and a relay SS is provided which is actuated upon the, energizationof the relay 101. An energizingcircuit is also established for a busy control relayBcRto prepare circuits in the operators busycontrol and. storingcircuits and in the operators sequence selecting switch circuit, as willbe inore fully hcreirr,

after described. An operatorslistening relay TLR is provided to control the'connection of-the-operators set to the cord conductor of thefcordC and a calling lamp CALis also provided which-wheh lighted to glow .steadilyindicates to the operator associated with the cord C, of which there are a plurality, that calls are stored at her position and when causedto flash will indicate to her that her; set has beenextcnde'd to this particular cord and a call'has been extended to her'position, as will be ClQSCIIbECl in detail when describing the detail operation ofzthecircuitsx A sleeve relayvSL' is 1 fully hereinafter described.

pervisory relay SR is also provided which is energized when the called subscriber anprovided which is'energized when the call ing plug CP isinsertdintoaqack of a called line, and aflbusy guard relay GU is also provided, which relay GU is energized upon the" energization of relay SL. A

party-line ringing key RKis provided and associated therewith are a plurality of ringing generators G, Gf, GP and (Li-for the usual signaling purposes A ringingcontrol relay RC, a ringing interrupter relay IR and a ringing trip relay RTare provided for controlling the application of ringing current to the called line, as will be more A calling suswers. A combined ringing and disconnect lump BL is provided for the usual purposes. 7 In the system of my invention I divide the-subscribers lines-of the exchange in groups of fifity each, and I associate therewith from six to eight finder switches FS,

N BEST AVAILABLE COP\' depcndinguponthe tratiicv of the group of lines and to which the fifty lines'are multipled. I also associate from six to eight finder switches FS' with the finder switches F S, and which switchesFS' are adapted to seek idle cord circuits C in the operators positions at the exchange switchboard. Assuming a ten-position switchboard and the switches FS being of the fifty-point type, five cords as C of each of the ten operator's positions will.be multipled to the eight switches F S These values as given above are only for the purposes of illustratcircuit is similar to the others and a de-' scription of the circuit f is suliicient, The A operators busy control and storing circuit f associated with the operators position F is provided with four'call storing relays CA, 3; 210A and CA, which are'of-the mar.- ginal type, in that the relay CA will operate through a 3000-oh1n resistance to round, which is placed in circuit with the re a CA upon the energization of therelayB R of The relay CA will operate through a 1500- ohm, resistance to ground, but not through of .the exchange switcha cord C which is seized to extend a.con-, nectlon to the trunk operators position F.

3000 ohms, relay CA through a IOOO-ohm resistance to ground, but not through 1500 ohms, and relay CA through a 750-ohm resistance to ground, but not through 1000 ohms, for the purposc'of storing calls before this trunk operators position F, as will be more fully hereinafter described. .Busy clearing relays BC, BC, BC and BC are also provided, which relays upon encrgization establish energizing circuits for the, po-

sition busying relays PB, P13 PB and PB", respectively, to. establish energizing circuits for the group busy relays BU, which relays upon energization busy all the cords of the operators position F when a. cord has-been seized in this operators position. I

Referring now to Figs, 4 and 5, I illustrate the operators sequence call selecting switches SCS, SCS', SCS and SCS, which are provii'le-tl four per operator. switches, when calls are extended to an operators position F, are operatedto select the SQlOzl'QCl cord circuit to operatively connect therewith. Wheircalls are stored at an og erators position as F, the switches SCS, etc, are operated and restored in a regular rotation. The switch SCS, which is typical of all four switches with which. each operameet-ice tors position is equipped, will he described. It is provided with wipers-118, 119, 120 and;

191, which, through the agency of a motor magnet lllM are stepped into engagement with the contact sets 122,123, 124 and 125 to se ect the contz cts to which the seized cord. circuit is mii'ltipleil. A bridging relaVBG is )rovidecl which when en'ernzed'.

connects 'the operatofisialking wires to the. cord conductors.

. also provided,which when-energized with- .storin lamp draws its retaining pawhto permit the wipers to restoreto normalnnder sprmgtensmn. Off-normal contacts 0N are also providerl, wh ch assume their alternate positionupon the first step'of the wipers ofi normal and are 'restoredto their normal position uponthe restorationotjthe' wipers to nor- Ina In 6 I illustratennhperators selecting switch OS,wh icheoinprises wipers 126, 127,, 128' next t-hi ou h the agency of "Zimotor magnet "MM topic "upthe calls extended to. an operators position in the order in. which they are received orstored' at an" operetors position. Abridging 'relay BG' is provided whiclnwhen energizedyconnects the opera- .torYs set O-, throughto the cord conductors. when bticon'tacts; e

Thei'switch is. titre-Po fell; and

RM? isengrgiie ho rele se mayf;i'gain he stepped the wipers so that they from one contact set to the next to connect the operators set ()"to'th cord conductors. A set of off-normal contacts ONf hre pro vided; which are "inoved to-their alternate position upon the firststep of the wipers off and 129, which are' stepped from one-contact set 130,131,132 and 133 to the normal and moved. back to their normal po- Y sition when the" wipers are restored to normal;

The'operators busy controland storing circuits f, h andy' foviae means for controL ling the busy w ion the operatorsset and cord are automatically. selected inzone 0 these positions. :A position remains busy as long as a particular operator has a greater load than any, adgacent same group), and the busy 15 remove whenever the operator has a smaller load, or one equal to the smallest load on any opera tors position in the same group.

l w 2: i

vided wherestoring feature is alsogpr by as many as four calls w y; he stored in 1 .M 1 trout of each operator. In-the cord circuit (l as described mconnect on with Fig. 2, ii CAL islighteti when a cell 15 normal contacts ON, conductor stored.

i the receiver at seer .AvAiLAeLE Cori switchesSGS," SCS, store the calls on the our switches SCS,- etc.,'

etc, also operate to intheir regular rotation. Y

operators switch OS, 'of which there is one.

for each position,

icksnpthese calls in the sequence in whi they are received and,

' Assuming now that suhstationA initiates traced from battery throughv the lower winding of the line relayJ-L-Rynormalconthe subscriber atthe a calhithejremoval of the substationestablishes an energizing circuitior thei-line relay LR,

tact 2 of the cut-off rel'ayiGO,.oonductor 3,

through the closed contaflof the substation.

switchhook, conductor 4, normal contact 5 of the cut-ofi' relay CO'to ground through the upper winding'of. the-line relay LB.

The closing of alternate Contac f the line relay LR establishes an energizing circuit for the rotary magnet RM of the finder switch FS, traced from-battery? through the winding of the rotary magnet RM, normal contact- 8 of themagnet RM, conductor- 9, normalcontact 10 of the oil-normal con-' tact ON, conductor 1l, normal.contact '12 SH, the starter conductor SW to groundat alternate of the line relay LR, The rotary magnet-- of the switching relay contact 6 Rlilcnergizing-steps the wipers 13, 14,

and 16 into engagementwith the first set of V 18, 19 and20. -Upon' the'first step'of the wipers 13,

contacts '17, I

14, 15 and 16 from their normal position, the} otimorm al con-' tacts ON assume their alternate-position, and the opening'of normal'contact 10 opens the initial energizing circuit of the rotary magnet RM, hilt a substitute energizing circuit is again established for the rotary niagnot RM 'upon the closure of its normal "con tact 8, this substitute circuit being traced rotary magnet RM, its normal contact 8, conductor 9, alternate contact 10, of the oil- 21, normal 4 contact 22 of the relay SH, conductor 23,to

operator (one in the extended to the. operators position, and in lit-ates to the operator at all timesthe numhe? of calls stored at her position. The switches SCZS, SCS', etc of which there are tourfor each operators position, also operate when cells nrecumiecteil to an OPQ'HtOYS pv-lsition, and when calls are stored the 18, 19 and 20, and.

r is established from hstterythrough the winding of the thus step- 18, 19 and 20 'in vsearch of of the, subscriber A, and 7 16 of the finder switch engages the. grounded contact '20 associated with the calling line A, an

I energizing circuit for the bridging relay. G, unveil tro -n ground at alternate contact 25 of the line relay LR, conductor 26. contact 20, wiper 16, conductor 27, normal contact 28 of the relay SH, conductor 29, normal contact 30, of the relay BF, conductor 32. the winding 33 of the relay BG, conductor 34 to battery 7. The low resistance path through the winding 33 of the relay BG shunts the rotary magnet RM preventing further actuation of the said magnet, and the wipers 13,

v 14, 15 and 16 of'the finder switch FS are '10 T and which lead to the line of the calling now in engagement with contacts 17, 18. 19

subscriber A. The closing of alternate con- Y tacts 24. and' 35 of they bridging relay BG establishes an energizing circuit forthe battery feed relay BF, traced from battery through the winding 36 of the relay BF,

conductor 37, alternate contact 35 of the relay BG, conductor 38, wiper 14, contact 18, to the closed contacts of the substation switchhook at the calling substation A, and

back through contact '17 and wiper 13, con-.

ductor 29 through the-winding 40 of the re lay BF, conductor 41, to ground at alternate contact 24 of the relay BG'. Theinitial energizing circuit of the relay BG is opened upon the energization of the relay BF, but due to its slow-to-release construction, a sub- I stitute energizing circuit is established for the relay BG, traced from battery 7, conductor 34, through the winding 33 of relay BG, make-beforehre'ak contact 42 of relay BF, conductor 43 to ground through the winding 44 of the relay BG. I

The closure of alternate contact to of the relay BG establishes an energizing circuit for the switching relay SH, traced from battery through the winding 46' of relay SlV, conductor 47, throughalternate contact 45 of the relay 13G, conductor 48, of the wiper 15, contact 18, conductor 49 to ground through the winding of the cut-oif relay CO. The switching relay SH, upon energizing, closes its alternate contact 53, establishing a locking circuit-for the relay SH, traced from battery through the winding 54 ofrelay SH, its alternate contact 53,'conductor 55 to ground at alternate contact 56 of the off-normal contacts ON. The closing of alternate contact 12' ot' the relay SH now extends the. comn'ion starting conductor b'lV through the said altcrnatecontact 12, to the starting conductor wire SW,

-wh'ich wire SW leads to the next switch the finder switch FS, conductor 60, normal contact 61 of the off-normal contacts ON, conductor 62, normal contacti63 of the relay 64, conductor 65 to ground at alternate contact 57 of relay BF. The relay CR upon energizing closes its alternate contact 66, establishing an energizing circuit for the rotary magnet RM, traced from battery through the winding of the rotary magnet RM, conductor 67, alternate contact 66 of the relay CR, conductor 68, through the winding of the slow-acting relay '69, conductor 70, normal contact 71 of the relay 72, conductor 73, normal contact 74 of the relay 64 to ground at wiper 77 ofthe finder switch F8. The rotary magnet RM, upon energization, steps the wipers 75, 76, 77 and 78 into engagement with the first set of con- I tacts 79, 80, 81 and 82, which lead to a cord-" circuit In an operators position. The rotary magnet RM upon energiza-tion opens its normal contact 59.to open the energizing circuit of the control relay CR, and the relay CR now de-energizes and the opening of its alternate contact 66 opens the circuit of the rotary magnet RM. Should the first, set of contacts engaged by the wipers 75, 76, 77 and 78 lead to a cord circuit thatis already in use, private contact 81 will be grounded and another energizing circuit is established for the control relay CR, traced from battery through the winding of the relay CR, conductor 58, normal contact 59 of the rotary magnet RM, conductor 60,-

alternate contact 61 of the off-normal contacts ON (said oft-normal contacts ON having moved to their alternate position upon the'first step of the wipers 75, 76, 77 and 78 from their normal position), conductor 68, through the winding of the relay 6S. conductor 70, normal contact 71 of the relay 72, conductor 73, normal contact 74 of the relay 64, conductor 84 to the grounded wiper 7 7 which is engaging a busy grounded contact 81. The relay CR energizing closes its alternate contact 66, establishing an energizing circuit for the rotary magnet RM to ground at busy grounded contact 81 over the previously described path, and the rotary magnet RM steps the wipers 75, 76, 77 and 78 into engagement with the next set of contacts 79, 80, 81 and 82. The rotary magnet RM upon energization opens its normal contact 59, allowing the relay CR to restore, and the relay CR restoring opens the energizing circuit-of the rotary magnet RM and its alternate contact 66.

It will thus be seen that due to the seesaw action of-the relay CR and the rotary magnet RM, the wipers 75, 76, 77 and. 78 are stepped from one contact set to the next, until an idle set is encountered. When the wiper 77 engages an ungrounded contact 81, no energizing circuit is established torthe relay CR, and the relay CR remains at normal and thus prevents further actuation of the jrotaryniagnetRM' and the wipers 'now remain" in engagement with the idle -contact sets 79, 80, 81 and 82. The Slow acting relay 69 remains energized. duringthe rapid energizations and de-energizations of the relay'CR, and its normal contact 85 is opened to prevent the energization of. the rclaytit, and when "an idlecontact set is encountered therelay 69restores and the closing of itsnormal contact 85 establishes an energizing circuit for the-relay 64 of the findcrswitch ES, traced from battery through the winding of- ;the relay 64,- the A conductor 86;"normal contact 87 of the relay 72. conductor'88, normal contact 85 of relay 69" to groundat alternate contact 89 of the elf-normal contacts ON.

The'closing of alternate contactl90 of the 'relay =64 establishes an energizing circuit for the relay" "72,ptraced' .from battery through'the winding of the relay. 7 2, con-' ductor 9L-altrnate contact90 of the relay 64, conductor'92 to ground at alternate contact, 89 no-filming-normal; contacts ON.

The closing vof. alternate contact 93 of the relay 'i'fiiestablishesia locking circuit for itself, traced irombattery through its windings anditsalternat'e contact 93, over conductor 94 ,to groundet alternate contact 89 of the off-normal contacts "ON'. The ini- 'tial energizing' circuito'fthe relay 64 is 7 opened atrnormalcontact 87 upon 'theen .ergization of the relay- 72, but a substitute energizing circuit is established for the re- "lay 64, traced from battery through the conductor97, to ground at alternate contact- 95-of the relay 64. The closing of'altcrnate contact 74 of the relay 6 places ground upon the private wiper 771/ hich busies the engaged private contact 81 to prevent any other switch FS' from engaging-th'eselected contact set. The relay 96 energizing, closes its alternate contacts 98 and99, and the dos ingot the said alternate contacts 98 an'd99 now extends the calling subscriber at the substation Alto the selectedidlc' cord circuit C at an idlc'operators position at the ex change.

The closure of altcrnatecontiy'ct 100 of rela-y 96 establishes an energizing circuit for therelay 101, traced from ground through the relay 101, condutor'lOZ} contact 82,- wiper 78, conductor 103, alternate contact .100 of relay 96, conductor 47 to battery and ground through the winding e6 of the relay SH. The relay 101 open energizaticn closes its alternate contact 105,,establishing an'energizing circuit for the secondary relay S S, traced from battery through the winding of the relay SS to ground at alternate contact 105. The closure of' alter nate' contact 106 of the secondary relay SS establishes a circuit' for the call line lamp CAL of the cord circuit-C, traced from battery through normal contact 107 of relay 108, through the lamp CAL, conductors 109 BEST AVAILABLE com a and 110, alternate contact 106 of relay SS,'

conductor 111 to ground at normal contact 112 of the sleeve relay SL. The lamp CAL 7 is lighted and burns-steadily and indicates to the operator that a call is storedather position; as will be more fully hereinafter described. The closure of: alternate contact 106 ofthe-relay SS- also establishes an energizing circuit for the-busy control relay- EUR of the seized cord circuit "C, traced from battery through the winding; of the relay BCR, conductor 110, 'alternate contact 106 of relay SS, conductor 111 :to ground at normal'contact 112 of the relay SL. The busy control relay BOB-energizing closes its alternate contact 115;.es tablishingian energizing circuit fertilecalled storing relay CA'of the operators busy control and storing circuit f, which circuit f is common to its operators position F with which the cord circuit C isjseizedby the switch F8. The energizing. circuitof the relay CA may be traced" from ground through the 3000-ohm resistance 172, alternate contact 115 of the relay BGR, conductor 17 3, which is common to all relays BCR of thecord circuits at'position 'F',-through the winding of the relay CA, conductors 174:

.and 175, normal contact 176 of the busy clearing relay BC, conductorsj177, 178, 179, normal contact 180 of the busy clearing relay BC", conductors 181,182'and 183 to battery through normal contact 184 of the busy clearing relay BC. The relay CA, upon energization, closes its alternate contact 185,

establishing an energizing circuit for the busy clearing relay BC, traced from battery, through the winding of the-relay BC,

to ground at alternate contact 185 of the relay CA.

- ,The relay BC. energizing closes its alter-' nate contact 186 to establish an energizing circuifii 'ifor the position busying relay PB, traced :t'rombattery through the upper winding 187 of the relay PB to ground at alternatecontact l86 of the relay BC.v The relay PB energizes over this circuit and closes its alternate contact 188. connecting ground to the conductor 3 10, which ground operates the group of busying relays BU associated with the position F, and the busying relays BU upon cnergizationclose their alternate contacts 189 temporarily busying the balance of the cords in this position by grounding the contacts 81 at the selecting switches, each cord having a-wire, as 190, leading to a relay BU. Thebusy potential and t thus placed on all the private contacts 81 eir multiples of cords at this operators position remains until the call which has been extended over this particular cord to herposition is extended to the called line, as will be more fully hereinafter described. The relay BCR upon energizing also closes its alternate contacts 191, 192. The closing of alternate contact 191 connects ground to thestarting conductor SA common to all relays BCB of the position, to close an energizing circuit for the motor magnet MM of the operators sequence call selectingswitch SCS, of which there are four for each op-' .erators position, for purposes as will be hereinafter more fully described.

IThe circuit of the-motor magnet Mhfl of v a the switch SCSunay be traced from battery through the resistance 193, the winding of ma et MMflits normal contact 194, normal contacts 195 of the oil-normal contacts ON,

conductor 196, nonnal contact 197 of the re lay 198, starting conductor SA, normal contact -199 of'thecord listening relay TLR, conductor200," to ouncl at alternate con- "tact "191 of 1 the re a BCR. The magnet MM upon ;-energization steps the wipe-rs 118,-119,120 and 121 into engagemenflwith the first setof contacts 122,123,124 and 125, and'upon'the first step of the wipers ofi normal, the off-normal contacts ON asa same their alternate position, and the motor and the magn inagnet-MM" "upon energization opens its normal contact 194 to interrupt its circuit, et MM now restores. The ofienormal co'ntactsflON having moved to 4 their alternate position, the initial eneragain energized over this circuit, and, due

to theopemng'and closing of its contact 194:,"it is thus alternately energized an de energized to stepthe wipers 118, 119, 120 and 121 from one set of contacts 122, 123,- 124 and 125 t0 the next, and when the wiper 118 engages the contact 122, whichwas:

ounded upof'i the energization of the-reay BGR of tie cord circuit C, an encrgiz 1n circuitis'estahlished for the bridging.

' re ay B6: of the switch SCS, which may he traced frombattery through the resistance 193, conductor 205, through the upper winding 206 of therelay RG normal contact 20701 relay 13G", conductor 208, normal BEST AVASLABLE cor contact 209 L the relay. 1-98, conductor 210, wiper. 118, contact 122, conductor 211, normal contact .2l2of the relay TLR, conductor213, to ground at-alternate contact 192 of relay BUR. 'The' relay IBGr upon energization closes its alternate contact 214, closing a locking circuit for itself traced from battery through the resistance 193-, conductor 205, through the upper winding 206 of the relay RG its alternate contact 214, lower winding 215 of the relay RG conductor 216, rwiper119, contact 123, conductor 351,th rough the winding of the relay TLR, condu' cto'r 217, toground at alternate contact 2180f the relay BCR. The

circuit through relay TLR also brings about its energization' for thepresently-be described. 1 r

The circuit just described, which causes the energization of-welay 13G: shunts the purposes as will motor magnet MM and' prevents further actuations of the said magnet, and theyvipers 118, 119, 120 and 121 remain in engage- 'ment with the selected set of contacts 122,

123, 124 and 125. Therelay BG upon energization closes its alternate. contact 204,

establishing an energizing circuit for-the relay 198, traced from battery through the ground at alternate contact 204: of the relay winding of the relay 198, conductor 219' to:

BG*, and the relay 198 energizing closes its alternate contact 220, establishing a locking circuit for itself from battery through its .winding, its alternate contact 220 to ground at alternate contact 221 Eat the bit-normal contacts ON The closing of alternate contacts 222 and "223,' o f the relay- BGr estab lishes an energizing circuitfor theline relay LR associated with the finder switch" SCS, traced from battery through the winding 36 of the battery feed relay BF,'asso' 4 ciated with the finder switch FS of the calling line, conductor 37,. alternate contact 35 of the relay BG, alternate contact 99 of relay 36, wiper 76,.contact-80, conductor 115, conductor 224, alternate contact, 225 of the relay TLR, conductor 226, contact "125, wiper 121, alternate contact 223 of the relay BG throughthe winding of the line relay LR, alternate contact 222 of the relay BG, wiper 120, contact. 124, conductor 227, alternate contact 228 of the'relay' .TLR, conductor 229, Contact 79, wiperu75, alternate contact 98"of relay 96, conductor 39, winding-31= of,relay BF, conductor 41 to ground at. alternate contact 24 of relay HG. The relay LR energizing closes its alternate contact 230, establishing an energizing circuit tor the starting relay SG, traced from battery; through the winding of the relay 5G,, tdground at alternate contact 2 0 of thearelay LRfl- The relay SG upon energization .closes its alternate contacts lOC 231i and '232, and the closingiof alternate contact 231 establishes an energizing circuit circuit (l of the position F, traced from bat- 50 I-wiper 118, contact 122, conductor 211, alter- Beer AVAILABLE corn for theswitching relay BG of the operators selecting switch OS, traced from 'fround at alternatecontact 231 of the re-- ay SG, conductor 233, con'tact131, wiper 127, conductor 234, normal contact 235 of relay 236, normal contact 237 of the relay BG", through the low resistance winding 238 of the relay BG, conductor 239,.through the resistance 240 to battery; a The circuit just' traced'through the relay 'BG" shunts themagnetMM of the switch OS, due to the low resistance path through i winding 238 of the relay BGfl and prevents the magnebMlll from stepping the wipers 126, 127,128, 129 of the switch. The relay B'Gv upon energiz'ation 4 opens its normal contact 237' anda substitute clrcuit 1s established for the said relay BG, traced from battery through the resistance 240, conduc- '20 701 239, throu h the windings 238 and 241 0f the relay normal contact 235 of the i set O' to the' cord conductors of the cord relayf23'6 to ground at alternate contact 231 i 0f. the relay SG over the previously 'deseribed' an; 1:

The c osing of alternate contacts 242 and 243 of the relay BG connects the operators circuit-C, froinl'alternate contact 242 of the relay KEG"; the Wiper 128, contact-132, con-.

ductor-'244,"'alternate contact 222 of relay BG wiper 1 20, contact 1240f switch SCS, "conductor 227, contact 228 ofthe relay vTLR,

conductor 229 to the tip strand of the cord C, and the othertlead from the operators set.O'-.e-iitends through alternate contact 24:3v

of. the relay 'BG the wiper 129, contact 133, conductor 245,1through alternate contact 223 of-the relay RG wiper 121, contact 125 ofv switch SCS; conductor 226, alternate contact--225 of the relay TLR, conduct-M224, to

thesleeve strand of the cord circuit C.

Referring again to the switch SCS,' t-hc energization of relay 198 causes its alternate contact 209 to close, to establish an energizingcircuit for the relay 108 of the cord tery through the winding of the relay- 236 of the switch conductor 24:7, wiper 12?, contact 130, "conductor 248, alternate conta'ct 209 of the relay 198, conductor 210,

hate-contact 212, of the relay TLR, to ground through the windingof the relay '108, which relay energizes over this circuit, but relay 236 of the switch OS does not, due to its const-ruction and adjustment.

The opening of normal contact 107 of relay 108 opens the initial circuit of the call lamp CAL, but a substitute circuit is established For the lamp CAL, traced from battc ry through .the rotating; interrupter 1,

through alternate contact 107, through he lamp CAL. conductors 1)?) and 110, alternate cont act 106 of. relay SS, conductor 111, to ground at normal contact 112 of relay SL'. The lamp CAL is'caused to flash over.

this circuit and notifies the-opt ator of the position F that her operators s1? has been extended to the cord -C in which the lamp CAL had been burning steadily aid that a call is awaiting her attention. The lamps CAL at an operators position are li hted and burn steadily when calls are eing stored at an operators position, but flash when the operator of a position at which calls are stored is available as will-,be more fully hereinafter descrih'. The operator's head set O having been connected'vto the cord conductors as just de'sc-ribed,"through alternate'contacts 225 and 228 of the relay TLR of the seized cord C, the operator noting the flashing signal CAL inquires the number ofthe substation thatis wanted by the calling subscriherat substation A and now tests the multiple jack J of the'wanted substation in the usual manner as to its idle or busy condition. a

Assuming that the line ispidle, the operator lat-the'po'sition F associated with the cord circuit inserts the calling plu CP into the multiple jack J" of the wants Substation D, thusestablishing a series finergizing circuit for the sleeve relay SL' of the cord circuit C and the cut-011;.relay C0 of the line circuit L associated with the called line,'traced from battery,'thr'ough the winding ofthe relay 'SL,cond-uctor 250, normal contact .556 of relay 547, conductor 249, sleeve contacts of the connected plug 'TP and jack J to ground-through the winding oilthe cut-oil relay CO. The relay- SL' upon energization opens its normal contact 1'12, interrupting'the flashing circuit of the call lamp, CAL, which lamp is now ellaccd. The insertion of the calling plug GP of the seized cord circuit G into the multiple jack ,l of the wanted line also establishes an energizing circuit 'for' relay 140 traced from battery through'the windingof relay 1 10, conductor 249, to ground through conductor 25, alternate contact 256 of re lay SS, conductor 257 to groundat alternate contact 25109 the relay SL. A looking circuit is closed through the lower winding 258 of the relay GU, traced from alternate contact 259, conductor 260, to ground at alternate contact 261 of relay SS, A locking circuit is also established through the upper wind ing 252 of the relay GU, from -l. altcr r through the winding 253:- of; the rela GU, its alternate contact 252, conductor 279 to ground at alternate contact 150 of the hattery through its-lower winding? 258, its

" removing the ground from the group of the relay GU are for relay 140. These two locking circuits for purposes as will be presently described. r The sleeye relay SL upon energization opens its normal contact 112 ,to open the energizing circuit through the relay BCR and the relav'BCR upon de-energization opens its alternate contact 115' and the opening of alternate contact 115 of relay BCR opens the energizing circuit of the relay CA of the cord operators control and storing circuit associated with this operators positact 186, opening the energizing circuit of .therelay PB and the relay PB upon deenergization opens its alternate contact 188,

busying relays BU. which "relays" now restore, and the opening of their alternate v 25 contacts 189 removes the busying grounds from the multiple contacts 81 of the switches BS in which the cords C of this operators position F terminate, making them again seleetable fso thatbother calls may be extendedito this operator's position F. H

The closing. of alternate contact 262 of the relay GU, however,-places a busy pot-en- .Lss,

tial upon the privatecont-act 81 of the selected-cord circuit C which may be traced from: ground at alternate contact 202 of the relay GU, conductors 263 and 264 to the contact 81', thus preventing any other switch,

,as F, from selecting this that is now in use. The re ay BCR upon.

articular cord restoration opens its alternate contact 218 to open the energizing circuit of the relay TLR of the cord C, and the relay BGr of the switch SCS. The relay TLR upon restora tion opens its alternate contact 212, allow ing relay 108 to de-energize, and the relay TLR upon restoration also opens its alternate contacts 225 and 228 to disconnect the operators set 0' from the cord conductors. The relay G upon restoration closes its normal contact 204, closing an energizing circuit for the release magnet RM traced from battery through the winding of release magnet RM, alternate contact 202 of relay 19s, conductor 203 to ground at normal conrestoration of the relay Ba, due to the closing of its normal contact 204, but the encrgization of this relay has no eifect on the circuit at this time. \Vhen the wipers reach their normal position, the off-normal contacts ON assume their-normal position, and

BEST AVAILABLE com theopening of alternate contact 221 of the said off-normal contacts ON opens the looking circuit of relay 198, and the opening of alternate contact 221 allows relay 198 to re- .store, and the opening of alternate contact turnopens the energizing circuit of the re-.

lay SG at its contact 230. The relay SG- upon de-energization opens its alternate contact 231 opening the energizing circuit of relay BG of the switch OS. and the relay now restores. The apparatus of the sequence selecting switch SCS and the operators selecting switches are now at normal .and the switches are again ready to select another call that may be extended to the operator's position F.

Returning now to the extension of a call to the called subscriber at the substantion B,

a circuit .foithe ringing lamp RL isestablished. traced from battery through the lamp RL, normal contact 274 of ielav RC,

normal contact 275-of relay 547, conductor- 273, normal contact 276 of relay 'RT, con 9 ductor 272, normal contact 277 of relay SR, conductors 278 and 279 to ground atalternate contact 150 of relay 140. The ringing lamp BL is lighted over this circuit, giving the operator associated with this cord C visual indication, notifying her that the called subscriber at the substation 'D hasas yet not been signaled. To signal the called-for subscriber at the substation D, the operator associated with the cord circuit C now depresses the proper ringing 'ke plunger of the ringing key RK to conne the proper ringing generator frequency 0 the generators G, G, G or G as the. case may be, to operate the call signal at the called substation D. a

Assuming that the ringing generator G is the proper frequency for signaling the plunger actuates the end spring contact 280,

causing it to'momentarily assume its alternate position, and the closure of said alternate contact 280 establishes an energizing circuit for the ringing control relay RC traced from battery through the winding 0 the said relay RC, conductor 2 81, alternate contact 280 of the end spring contacts of the ringing key RK, conductor 282; normal con-' tact 275 of the rela y 547, conductor 273, normal contact 276 of relay RT, conductor 272, normal contact 277 of relay SR, conductors 27 8 and 279, to ground at alternate contact 150 of relay 140. The closing of alternate contact 2740f the relay RC establishes a =ch'ergizcil over this circuit, and the closing "of its alternate contact 293 connects the sei' lectcd generator-ti to the tip cord conductor of the-cord circuit G to operate the call belllzat '-tlic*called substation D to give the subscriber ther cat an instantaneous first ring', as is well understood; The'openingo't j g fnornial contactfl'l' lfotfthe relay RGppens the-circuit otthe ringing lamp BL, and the [closure 'ofalternatecontact 284 of. the relay RC clos e's "an energizing circuit for the ra t-m relay traced from battery it ,h'ftltc''1winding"160 of .therelay IR,

'i' y amen 'terru'pter I to ground. The relay IR is "thus" intermittently energized and de-cner- *gized by the interrupter I and the ringing currtiiit froin the generator G is thus con- 'nectd and-'dijscdnnccted :t'o intermittently "'3 operate, the called signal, atthe called-for 'sulistation 'Df 'lIhe ringing current may be .35

"the coiistantlyjrotating incra'torfiG' through the closed key plunger contact-of the ringing key BK, conductor 28tiy-through' the winding-of the ringing trip relay RT, conductor 290, alternate contact 293 of the interrupter relay IR, tip contacts. of the comiectcd plug CP and jack J, through the condenser and call bell to the called substation D,- back through the ring contacts of the connected jack J and plug GP to batteryand ground throughaltcrn'ate contact 294flotthe ringing interrupter relay IR. The call signal at the substation I) is thusintcri'nittently actuated due to tho'encrgimtion andde-cnergization-of interrupter relay IR, and'the subscriber at the substation l), in response to his call-sigeeniorcs his receiver from the switch- Should ,tliesuhscriber at the substation D remove his receiver during a ringing pcriod, the combined generator andbattery flowing through the winding of the ringing tri relay RT causes the same to actuate, an the opening of its normal contact 276 opens the locking circuit for the ringing control relay RC, which relay RC resares, and the "opening ofthe alternate if-K310i? 528i disconnects interrupter I from thz'. winding 160 of interrupter relay 1R, and the relay 1R- now'restores to normal and prevents farcontiict'QSti'of relay RC. The-relay IR is- 112 of, relay SL; and the o ening ofzitsnor alternajtez' contact 284; of -re-- a-ua'fmm the uugrouniled pole or the. gem.

BEST AVAlLABLEQOPY ther application of ringing current after the called subscriber at the substationD answers iuresponse to his call signal.

Should the subscriber at the substation D remove his rcceiverduring a silent period, that isQwhcn theringing interrupter relay ER is in one of its cleenergized positions, an cumrgizing circuit for the-supervisory relay Si established, the circuit .heing traced from battery through: the upper avinding'of the relay SR, conductor 295,-alternate c'on- .tact 296 of relay SL, normal contact 293 of the relay-1R, ring contacts of the connected Y plug GP and jack J through the now closed contacts of the substation switclihook at the.

substation D, back through the tip contacts of the connected jack' J and plug GP normal contact 294- of the relay IR, alternate contact 291 of relay, SL, conductor-292,

through the lower windin'gjof relayISB, conductor 297, to ground at' alternate contact nial contact 217 ppe'ns the ockingcircuit of r lay RCto pre' \=ent-.--ui ther application of ringing current.

The closing of alternate relay SR establishes an energizing circuit for the meter battery connecting relay MBR, traced train-battery through the windingof the meter battery connecting relay 'TMBR; conductor 298, normal contact 4000f relay 'lOlgeonductor 40:2, alternate contact277-of relay SR. conductor 278, to groundlat alternate contact 150 ofrelay 140. The relay 'MBR upon energization closes" its alternate contact 4H3 connecting the high voltage battcry VB to establish anenergizing circuit for meter-relay associated with the. calling line and which is located at the main ex-- change,-and which may be connected in circuit through the medium of a meter Jack MP an'd'a suit-able plug associated with-the.

in'cter mechanism.- The closing of relay MBR establishes an nergizing circuit far the relay 401, traced from battery through the upper wintling,of 1'elay 401, conductor 406 to ground at alternate contact alternate contaot of 405. ltelay 401 upon energi-zation closes its alternate contact 407, establishing a locking" circuit for-itself, traced from battery. through its lower winding, its alternate contact 407, conductm's 408 and 279 toground at alternate contact 150 of relay 1.40. for purposes as will presently be described.

The subscriber at the substation A and the subscriber at the substation D are now in conversational circuit, the talking circuit being traced over the heavily marked oonductors; I

Assuming now that the subscribers .at the substations A and D have finished conversation, they replace their receivers upon their respective sivitchhoolcs. The replaoin of the receiver by-the subscriber at the calling tact 22 of relay SH, conductor 23,

substation A opens the circuit of the batto feed relay-BF ofthe finder switch F S an the relay BF tie-energizing, its alternate contact 42 is opened, opening the energizing circuit of the bridging relay BG. Belay BG tie-energizing its normal contact 24 is closed, establishing an energizing circuit for the release magnet REL, traced uponthe restoration of the wipers and the of the cord circuit ductor 411', alternate" contact 412 opening of alternate contact 56 of the oil? normal contacts ON 0 ens the energizing circuit of relay SH, w ich relay restores, and the opening of alternate contact 22 of relay SH uponits'restoration opens the cirduit of the release magnet REL and the finder switch F S is now at normal.

" The relay BF upon restoration as above described also opens its alternate contact 57, o ning the locking circuit of the relay 64 o the switch FS, and the relay 64 upon restoration closes its-normal contact 90, establlslnng an energ1zing circuit for the release magnet", REL, traced from battery through'the'winding er m'agnet REL, conof relay 72, normal chntact 90 of relay. 64, conductor 92 toground' at alternate contact 89 of the oft-.nqrmal contacts ON. The release magnet R upon energization withdraws the retaining pawland allows the wipers 78, 79, 80 and 81 to restore. The off-normal contacts ON also assumetheir normal position when the wipers of the switch FS have restored, andi'the opning of alternate contact 89 of ofl-norr'iial-contacts ON opens the'locking'circuit of relay 72 which now restores to normal R elay (it having restored to normal, its alternate contact 25 .is opened, thus openin the energizing" circuit of relay 96, which re ay now restores, and the switch FS and its associated parts or mechanism are now at normal. The switch FS having restored to normal, the circuit of relay 101 C which was seized finder switch FS to extend the connection to cord circuit C is opened, and the relay 101 restores, and the opening of its alternate contact 105 opens the energizing circuit of therelay SS, which relay SS now restores to normal.v The opening of alternate contact 261 of relay SS opens one of the looking circuits of the busy guard relay GU by the plug CP is in the jack J v 1,594,898 BEST AVAILABLE Cot the windin of relay which extends throng? I d remains 00 e up to 258, but the relay G ground at alternate contact 150 of relay 140 through its upper winding 252 over the circuit as previously traced. Relay SS upon dcenergization closes its normal contact 611, establishing an energizing circuit for the relay 547, traced from battery through the relay SR, conductors at alternate contact lamp BL is lighted 278 and 279 to ground 150 of relay 140. The over this circuit .and notifiesthe operator of the position F associated with the cord circuitC that the calling subscriber has replaced his receiver and that conversation has terminated between the'calling subscriber at the substation A- and the called subscriber at the station D. The relay SL upon de-energization brings about the energization of the relay 547, which in turn allows relay SL to restore, but as relay 140 is connected in multiple with the sleeve strand of the cord C, it remains energized, and due to its high resistance permits the cut-off relay of the called line circuit to derenergize, placing'the line circuit of the called line at normal to permit the called subscriber to initiate a call, even though the plug OP remains'in the jack, or he called. Relay 140 remains oncrgized to ground through the cut-off relay ot' the line circuit IL -TR, conductor 272, normal contact 277 of of the called line andthe locking circuit of ,the busy guard relay GU through its upper winding 252 and the cont-act 262 of relay GU is thus held in its alternate position connecting ground over conductors 263 and 261 to the iiriivate contact 81 of the finder switch FS. The condition will exist as long, as the calling plug CP of the cord C remains in the jack J" of the called line and the ground that is extended to contact 81 busies the said contacts and prevents any other tinder switch as FS from seizing the cord C as long as its of the called line. The operator noting the lighted signal RL removes the calling plug CP from the jack J which opens the circuit of the relay 140, and the relay restoring its alternate contact restores and opens the locking circuit of relay GU and the circuit of relay 547.

Relay GU restoring, its faltern'ate contact 262 is opened, removing the busy' ground 1 from the private contacts 81 of the'finder switches-'1 S' and the apparatus that was 6 used inestablishinga conneetion from the 'callingsuhscriber :it the substation A'to the ealled siibseriber'atsubstation D is now at normal-"and available for establishing other connections.

' 'In'"the-foregoing";description I. have sinned that all-the. apparatus ras in its norxnal unactu ated position, but for a clearer understanding of'th'e' trunk op'erators liusy control an(l' 'stor ingeji i ef 'itof 3 and the '1 5 .ogerators sequence selecting circuit of Figs.

- 5 and I will now drserihe more in tie-- tail the'operntion'of the: circuits, .i'hcucalls g .zire being, s toretlheforethe different opera; -..".tors" pesiti ons 'andth method of selecting "thecalls in sequehe bfi means oi? the operai':*i'ni'.F igs .-f4 ',""5 ancl'fi v T "Z .Assuining nowflth Qthe operatorsat p si- H- zind Jfare idle and-that the first i hasfelecl1ed thereof-(l as h}thelofiei atorsposition F, as nrr ievioiis rlescriptio'u relays '1'; SS. and BCR fare energized, and the closure ofthe."alternate'contact:1'15 of rehiy BCR of i tors. ',sequence;Seleeting',,eii cuits l illhsztratetl the selected lco'rd, C connects the 3000 011121 operator. that t call is sturetlather position.

Assuming that the 'operator at position F does not'answer this call, the seeond call e.

1 tended to the exehangefwill-seleeta co rd circuit as C in the operatofls'position H. Ilelays '1 SS and BCR of the cord C seized in the operators position II Will'oporate in alike manner,.and'theclosing ofnlternate contact 115 of the relay BCR will connect ground through. the iltlQO-uhm resistance through the winding oflrelay CA of the op.- erators position H to battelj' at normal eontact 184 of the relayBC' associated with l the operators position H. Relay CA operates-3 to close an energizing circuit for the relay BC, due to the closure of alternate contact 185' of the relay CA. The relay BC energizing in turn establishes an cner-- gizing circuit for the relay P15 from ground through alternate contact 186 of the relay 35C", and through the winding: 187 of the relay PB to ground.. Relay PBlP-RGIglZlHQI;

85 its ahe'rnatcontuct .83 is closed to est-ah tion J.

alternate contact'ilfili of the relay BEST AVAlLABLE com lish an energizing circuit forthe group busy mg relays BU associated w1tli'theoperat01"s position H, which relays BU operating close their alternatecontacts,'-placing.a ground-or husy potential upon'the rest'of'the" cords in this pos'atimr H. The lamp CAL of. this cord C associated with the positionll now glows steadily, indicating to the operator .thatacall is stored at'her position. 1

Assun'iing that. the operators-at positions F and ll. (lo not answer-either call anil that a third (all is extended to the position J the relay CA ,as'soci'ntell with the position QT -\:ill operate from ground throng-h the 3000- ohm resistance of the selected oiitl circuit C ofQthe operator's position J, througlrthe winding of the i relay CA? to battery at'noruiul contact 184? of relay BC- of-tli'ej'posi- The clo ing of alternate contort 155 of rela Cl.\.'* rinses a eirruit t hrough ruin) RC Whirl] will he energized to in turn How a cire-uibfrir the relay PB=. from bat,--

- only position hi1 ring cords as C not busy, the

ltQ' through its upper" winding :18? :to

l,(}'-'. and the closureof':1lternate= c611tact 3 14; of rr-.l1\ I}C'-'. (loses a circuit through the. lower winding ilfil Iof'ri-lay PB Qfi-om luttory through the winding w361,-alternate contact 360 condurtor fil alternate contact 362; of the relay BC of the posit-ioirll,

alternate (contact 363 of the relay BC of the position F to gromul. j The elosi'ugof; alternate contact 36 1 of the relay BC atthe position J now closes a-eircuit through the lower winding ihilpi' the relay: PB" of the position H, the llvlllt .heing"tmrcodfirmn buttery through the lower winding 36]., alternate contact 2360' of therelay BC, con doctor 36?), the alternate contact-3660f the relay [1C ofthe position F, conductor 367,

'allernate contact 363". of rel y RC of posi- Thor-losing of alternate contact 36 6 of the relay BC of position J. closes a pircuitr through the lower winding 361 of the relay ll'; of the position F'traeecl fronrbattery through the winding 3G1, alternate contact' 360 of the relay BC of the positi0n F., eon: (meter-368, alternate-contact- 366 of the reluyBC' o? the position H, conduct 1"369,

d" of the position J' to ground: The .eircuits through the lower windings 361, 3615, 361

of the relays PB. PPI'and PB" at the :positions F, II ancl J bring about the de-encrgization of the said relays at the respective positionsh, H and-J, due to their di-fi'eren-- tial construct-ion, and the opening of their alternate contacts 188,188 and'188 removes the ground from conductors 340,; 340' and 340= to open the circuits of each of, the groups of busy relays BU- assoeiated with the positions F. H and J. thus removing the busying ground from all the cords not in tact 184 of'the relay 182 and 181, nonnalco'ntact 180 of the relay tion. F, which relays upon use. The lamp CAL of the cord C seized in the position J is now lighted and burns steadily and indicates to the operator of the position J that a call is stored at her position. Assuming that the operators at positions- F, l1 and J have not answered any one of, the three calls and a fourth call comes in, and assuming that position F is selected, the relay BCR of the seized cord circuit C associated with the position F that is extending the call to the operators position F closes its alternate contact 115,. plac ing an additional 3000-ohm resistance 172 in multiple of the common conductor 173, and the two 3000-ohm resistances 172 placed in multiple of the conductor 173 reduces the resistance to 1500 ohms, and as the relay CA will operate through 1500 ohms the relay CA of the position F operates over a circuit traced from battery at normal con- BC, conductors 183,

BC, conductors 179 windingvof the relay through the winding of the relay CA and over conductor 173 to ground at the alternate contacts 115 of the two relays BGR of the cord circuits C thatare selected, now that another call has been extended to the operators position F. The lamp CAL of the second cord C seized in the position F now glows steadily and we now have two and 178 through the lamps CAL glowing at the position F, indicating that there are two calls stored at this position. The relay CA upon energization closes its alternate contact 185 to bring about the energization of relay BC and the relay 'BQ in turn closes a circuit for the relay PB, and relay PB upon energizetion closes-its alternate contact 188 to again establish an energizing circuit for the busy group relays BU associated with the posi energization again close their alternate contacts to busy the remaining cords at the operators position F.

The fifth incoming call will be extended to position H and cause the energization of the relayCA associat d with the position H, the said relay GA energizing in a simi lar manner to that described in connection with relay CA of position F, whereby two resistances-172 placed in multiple with the conductor 17 3 permit the relay CA* to energize for the same reason as described in connection with relay CA of position F. The

relay CA upon 'energization closes its alternate contact 185* and brings about the energization of the relay BC. which in turn closes a circuit for relay PB, and the relay PB upon e'nergization closes its alternate contact 188" to operate the busy group relays BU associated 'with the position H o eausethe remaining trunks at the position H to be'busied, against selection.

lay BC to normal due to CA, conductor 1745 the relay CA BEST-AVAILABLE- com The sixth incoming call extended will be extended to the CA. to from the preceding, and relay CA in'turn brings about the energization of the relay BC through its alternate contact 185. Re-

be ener nate contact to close acircuit through the upper winding of the relay- PB, but the relay PB, due to the dilfereutial' construction restores to normal, as a circuit is also closed through its lower winding which brings about he de-energization of this relay PB. The differential relays PB and PB of the positions F and H also restore through their lower windings over circuits corresponding to those described .in connection with the first three calls that were stored at the operators positions F,-'H and J. The relays PB, PB" and PB open position J to causethe relay I gized in a mannerwbvious,

upon energization closes its altercircuits being closed.

their alternate contacts to permit the deenergization of the busy group relays BU associated with the three positions F, H and J, and eachlgroup of relays BU associated with said position will cause the repositions F, H and J maining cords in the to again test idle.

Assuming that none of the six calls thus far extended to the positions. F, H and J have been answered, a seventh call coming in will again be extended to the position F, and as relays BC and B0 of the position F are energized, the normal contacts 176 and 180 of the relays BC, and BC are opened and such seventh call will be extended to a cord circuit C at the position F the energization of the relay BCR at that cord, and the closing of its alternate contact 170 will place another 3000-:hm-resistance 172 in multiple with the other two resistances 172 of the two other trunk cords G and bring about that have been connected. The resistance about the energization of the relays BC and PB. The relay PB energizing, its alternate contact 188 is closed to energize the group busying relays BU, which relays BU in turn busy the remaining cords at the operators position F.

An eighth call coming in will operate in a like manner as described in connection with relay CA. and the relay CA upon energization brings about the energization of the relay PC and PB, and the closing of the alternate contact of the relay PB operates the busy relays BU associated with the posit-ion H, busying all the remaining cords of this operators position.

A ninth call coming in will be extended to the operators position J and cause the energization of the relay CA of position J 111 the same manner as described in connection with relay Ci and the relay CA in turn closes the circuits .for the relay BC and the relay PB The relay PB will-not energize, due to a circuit now being closed through. its upper and lower windings, which circuit is closed upon the energization of relay BC", and due to the differential construction of the relay PM, the relay remains atnormal. Circuits are also established through the lower windings of the relays PB and PB of the positions F and H upon the energization of relay B of positions J, and due to their dillcrential construction they restore, and due to the opening of the alternate contacts of the re lays PB, PB and PB at the positions F, H and J, the circuits of each group of group busyin relays EU will be opened and permit the e-energization of their assoelated-group busying'relays BU to remove positioris r, n and a.

A tenth call coming in will be extended to the operators position F, and, a cord circuit C having been seized in the operators the bu'sv from the remaining cords at, the

position F, a fourth 3000-ohm resistance 1'72 relay CA is energized in the same manner relay CA, and'thc relay GA in turn 7lll'b1l1lg' about the euergwation of the relays BC and PB, and the relay PB in turn will bring about the cnergizaation of the group busying relays Bil associated with the position H to lousy the remaining cords in this position.

A twelfth call coming in will be extended 'to the operators -position J and cause the energization of the relay CA in the same manner as described in connection with relays CA and CA, and the relay GA upon energization will bring about the energization of tlie relay EC. No energizing circuit is eliected for the relay. PB? of the position J, as a circuit is also closed through its lower winding, and due to its difilerenuction l PB de energizes; Relays 1 if and P i the positions F and H are also de-ene ducto the circuits being established ll: ugh. the lower windlugs upon the energization of relay B0 of pos ion J, and. due to their dillercntial construction they restore to normal, and the opening of their alternate contacts will perinit the de-energization of the group of group busying relays BU of the respective positions F, H and J, removing the busy from the remaining cords'at the operators positions. 1

For a simple understandingand description of the circuit operation, I have in the foregoing assumed that the calls camein to the various positions in regular sequence, that is, 1, :2, 3 order, top level, then 1, 2, 3, or(lcr,'sccond level, and soon down to the bottom level. It is, however, obvious that in actual practice such regular sequence would rarely, if ever, occur. Now that the regular order operation is disclosed, it is apparent that the organization of the. system as a whole assures merely the desired method of operation, which is that each operator of the group F, H, J, has one stored call, (i't making absolutely no dillercnceinthe cir curt organization which'of F or H 'or- J got the first call or the last call) before a second call can be stored before any operator of the group. l-"r: the circuit organiz call stored at one position happensto strike F, H or J, The organization of circuits, however, does guarantee to eachopcrator that she will not have .a third call stored more, it is indifferent toation whether the second;

against her until the operators each-have two awaiting attention. Inother vords,

the calls will in actual practice be stacked up. at hazard, as one might say, exceptthat no operator can ever have more than one call more than any other oper tor.

lu the description thusfar I'havc assumed that twelve calls have come 11: and nonejof: I

them were answered, so that each of the post-.1 trons F, H and have four calls stored n each position.

Four cords C have been seized in each operators positionF, H and J', as ust de-Z scribed, and from the preyiou's description it is remembered that'relays T SS and BCR are energized as soon as switch FS seizes the cords C in'the positions F, H and J. The energization of each'ot'the relays, 535% of the'cord circuits C Will bring about the lighting of the' four lamps CAlLat each opcrators position F, H and J and shows that four calls are stored at each of the operators positions. henthe lust call M was stored in'the operators position'F, the relay BC'R was energized, and the closure of its alternate contact 191 of the relay BUR:

closes an energizing circuit for the notor magnet MM of the sequence call-selecting su'itch $65, of which there are four for each opcrators position, and the motor magnet MM steps the Wipers 118, 119, 12c and 121 into engagement with the set of contacts 122, 123, 124' and 12-5 which lead to the seized cord C.- The second call stored at the position F causes the relay BCR of the second seized cord C to close its alternate contact 191 to establish an energizing circuit for the motor magnet MM of the switch SCS associated with the operators position F, the circuit being traced from battery through the resistance -'193-'through the winding of the magnet MM its normal con- 15 contact 191 of the relay BCR of'the cord C that was seized in extending the second call to the operators position F.

The motor magnet MM of the switch SOS. is energized over this circuit and steps thewipers 118, 119', 120' and 121 into engagement with the first set of contacts 122, 123', 124' and 125. Upon the first step of the, switch wipers oft normal, normal contact 195' of the. off-normal contacts ON 3 is moved. to its alternate position and a substitute energizing circuit is established for the motor magnet MM", traced from hattery through the motor magnet MM its n01:

- mal-contact 194, alternate contact 195' of the off-normal contacts 0N conductor 201', normal contact 202, conductor 203,. to ound at normal contact 204 of the relay G. The motor magnet MM steps the wipers 118', 119', 120 and 121' from one 5 contact set 122, 123, 124 and 125 to the next, and when the wiper 118 engages the grounded contact 122 which is grounded. through alternate contact 192 of the relay BCR ofthe cord 0, an energizing circuit 40 is established for the relay BG from the .said. ground at alternate contact 192 of the relay BCR of the cord G that was seized in extending the second connect-lento the operator at osition F, through contact 122, wiper 118 normal contact 209 of the relay 198, normal contact 207 of the relay BG through the winding 206' of the relay BG conductor 205 through the resistance 193 to battery, The circuit through the relay 13G shunts out the motor magnet MM of the switch SOS and prevents further stepping I r of'the wipers of the switch.

The closin of alternate contacts 222 and 223 of 'relay BG brin 's about the energization of the line relay TAR; and the line relay LR in turn closes in energizing circuit for the relay SG. The closing of. alternate contacts 204 of relay 13G: closes a-circuit for the relay 198 from battery through its -winding 198', conductor 219', to ground at alternate contact 204 of the relay. 13G; the relay 198 then closes a locking circuit for itself through its alternate contact .220 to ground at alternate contact 221 of off-normal contacts ON." The closure of alternate BEST AVAILABLE com contact 214' of'relay BGr closes a locking circuit for itself from battery through its upper winding 206', its alternate contact 214, through its lower winding 215', wiper 119, contact 123', through the winding of the relay TOR of the cord C that is seized in extending the second connection to ground at alternate contact 218 of'the-relay BCR of the second cord seized to extend the connection.

The third call having been extended to the operators position F causes the relays T, SS, BCR- of the said cord G to energize, and the closing of alternate contact 191 of relay BCR of this thirdcord C establishes a circuit for the motorniagnet MM" from the ground that was placed on the starting conductor SA due to the closing oi alternate c0ntact 191 of'the relay BCR of the third cord, through alternate contact 197 of the switch SCS, over conductor 380, through alternate contact 197- of the relay 198 of the switch SCS over conductor 381," ?throu h normal contact 197 of the relay 198.? of the switch SCS conductor 198*, normal contact 195 of the off-normal contacts ON, normal contact 194 of the motor magnet MM, through the winding of the motor magnet h'lM, through the resistance 193 to battery.

the relay BG, and the relay 13G upon energization shunts out the -motor magnet .Mh-tP and prevents further stepping of-the wipers oi the switch SCS Relay 198 relay LR and relay SG are also energized.

The fourth call that is extended to the position F selects the fourth cordcircuit C associated with the operator's position F, and brings about the energization otthe relays T, SS, 13GB of. the seized cord C, and the closure of alternate contact 191 of the relay BCR of this fourth trunkcircuit C that is extending a connection to the operators position F places a ground upon the common starting conductor SA and brings about the energlzation of the motor magnet MM of the switch SCS, circuit being traced from ground on the starting conductor SA, through alternate contact 197 of the relay 198 of the switch SGS, conductor 380, through alternate contact 197 of the relay 198' of the switch SOS, conductor 381,

through alternate contact 197 of the relay 198 of the switch SOS, over conductor 382, through normal contact 19'i ot relay 198

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