US1624953A - Telephone-exchange system - Google Patents

Description

fly. 5.

il 19 1927; l 624 953 Apr w. c. JORDAN TELEPHONE EXCHANGE SYSTEM n Filed Deo. 15. 1923 7 Shees-Sheet 1 ffy,

A ril 19 1927. 1,624 953 p. w. c. JORDAN TELEPHONE EXCHANGE SYSTEM Filed Dec. l5, 1925 l 7 Sheets-Sheet 2 y1,624,915 April 19, 1927. W. C. JORDAN `3 TELEPHONE EXCHANGE SYSTEM Filed Dec. 15, 1923 '7 Sheets-Sheet 3 ll f Mvg/wbr. 14//7//0/77 C Jordan April 1'9, 1927. 1,624,953

W. C. JORDAN TELEPHONE EXCHANGE SYS TEM Filed 1986.15, 1925' 7 sheets-sheet 4 o o oo no o o 1 I27. April 19 9 w. c. JORDAN TELEPHONE EXCHANGE SYSTEM Filed DeG. l5, 1925 7 Sheets-Sheet 5 NQ@ .Sh fg@ April- 19,'1927. 2,624,953

. w. c. .JORDAN TELEPHONE EXCHANGE SYSTEM Filed Dec. l5, ),923 7 Sheets-Sheet 6 April 19, 1927. y Y W. C. JORDAN TELEPHONE EXCHANGE SYSTEM m. N EN al. l

'Filed'. Dec'. 15, 1925 tors cord circuit shown in the upper left portion of the figure. In the lower right corner o1' the ligure, a key indicator link associated with the operators position is also diagrammatically illustrated.

Fig. 6 shows an incoming selector circuit in which the trunk circuit o1' Fig. 5 terminates, together with the control circuits thereof.

Fig. 7 shows a final selector switch accessible from the incoming, selector switch of Fig. 0, together with the control circuits thereof and a multi-station line terminating in the terminal bank of said switch.

Fig. 8 is a` diagram showing the manner in which the several ligures oi' the drawingv should he arranged to show the complete circuits illustrating the invention.

The toll line and associated equipment shown in part in Fig. 1 is of the type disclosed in the Patent No. 1,617A13, issued to Lewis A. Mortimer, on February 15, 1927.

vOnly such portions thereof as are necessai-y to au understandino,i ot this invention have heen disclosed herein.

The toll line-switch o't' Fig". 2 is ot the ro- '.ary type, lhaving' a clutch magnet and a stop magnet, the circuits tl crco't being slightly modified for the purposes et this invention.

The district selector ot' 3, the incoming selector of Fig. G and the iinel selector of Fig. 7 are of the well known power driven panel hanl: Itype disclosed in the patent to E. B. Craft and J. N. Reynolds 1,123,690, issued January 5, 1915, the circuits` ci these selectors heine; substantially similar to the circuits ot corresponding selectors disclosed in the Patent 1,395,977 yisued to F. A. Stearn and F. J. Scudder, November 1, 1921. r1`he district selector circuit et' Fig. 3 is, however, inodilied hy the introduction o1l the novel features ot the iniv'ention to enable this selector to function in the extension oit toll connections.

rlllie sender diagrai'ninat"cally illustrate( in Fig. 1 is ort the general type disclosed in the patent to O. A. Kopp, No. 1,509.1;11 issued Sept. 23, 1924. Only such portins of iFhe .sender have heen disclosed as are considered lessential to an understanding` oi the invention.

Establishment '0f connection.

1t Iis thought that the invention will loe liestiinderstood from a` detail description of the manner in which a toll connection may he established treni the toll operators position 125 of Fig. 1 to the .suhscrihens line terininating` in the iinal selec-tor switch 750 of a machine switchi-r-rgy Aotlic The toll operator at position 1,25, having received the instructions, in the welfh-llriiown mannen :t'or c1:- tend-ing,r the desired toll connection tests for idle toll lines `and assu-ming the line 150 to he the first idle line encountered, inserts plug 120 into ack 121, whereupon relays 104 and 101 operate in a circuit extending troni hattei'v 'hrouffh the windine' ot mareiiial re` f Q C *D lay 103, winding o't relay 104, normal contacts of dialingv key 105, normal contacts ot ringing' key 102, sleeve contacts oli plug 120 and jack 21 to ground through the windings or relays 101 and 100. Relays 103 and Y do not oiicrate at this time, the former heine' marginal and the latter beingv i'esllionsire to low Yfrequency signaling: current and .strong direct current only. Relay 104i: in operatingv prepares a circuit t'or the supervisory lamp 106, and relay 101 at outer mature disconnects relay 127 from the tip and ring conductors oi' the outgoing end of the toll line and at its inner armature closes a circuit for operating' relay 1211. rilhe circuit for relay 12e may he traced 4from th negative terminal or the high voltage battery 137, outer right and `inner right nach contacts of relay 1.26, winding of relay 124.1, lett hack contact ot relay 126, conductor over the composite legot toll line 150, com ductor 129, inner contact of relay 101, winding or polarized relay 130, hack contact oit relay 100 to ground. The direction ot current in this circuit is such to prevent polarized relay 130 from operating' at this time. Relay 124i, hor-rever, operates, closing a circuit Ylfor slow-tooperate relay The circuit of this relay extends from battery through the winding oi: the relay, the left hack contact of relay 11.9, the hack contact of relay 123 to ground at the Contact ot relay 124. Relay 122 upon operating,l close.; a circuit extending from ground through its con* tact over conductor 1410 to battery through the winding of relay 208, which latter relay operates and in turn establishes an 0h rions circuit 'for relay 211.

Relay 211 at its inner le'lt Contact estab- .lisies a circuit iior relay 119 extending; from `cattery through the winding 'of relay 119, conductor 139 to ground at the inner lett contact og1 relay 211. Relay 119. in attracti c' its right armature, disconnects the ringing' relay 11S 'troni coiidnctor 12S and the tip side of the Jroll line duringT the dialingr period and at its lett armature opens the orig'- inal enersgirainev circuit for relay 122. which relay thereupon releases removing` ground from the winding` ot relay 209. Relay 208, however, remains operated in a circuit eX- tendingj om hat y throuh its winding, conductor 1410, the vleiit front icontact oi'. relay 119, the hack contact or relay 123 to ground at the Contact ot relay 124. At its outer rigr'ht contact. relay 211. :prepares a circuit 'tor relay 2111- and at its inner right contact prepares a circuit tor relays 220 and 216.

At its outer lett Contact, relay 21.1 estalilishes a circuit for the stop magnet 212 which .may he traced from battery through the winning ot magnet 212, the outer right arlter.

contact et relay 214i, the back contact olf relay 216, thence to ground at the outer lett contact of relay 211. Magnet 212 upon energizing' closes an olwious circuit for the rotary magnet 218 et the line switch 25() which thereupon (narrates, causii Y the line switch lo start hunting' to an idle district selector. The hunting' movement or" the line switch continues until 'the brush 221i engages a test terminal associated with an idle district sclector,` the lest terminals et idle district selectors being` inarlqed by lull batter potential. lector i350 of lire. ll is the lin-it idle selector 'found idle. llllhen brush 221 encounters terniinal 220, a circuit is established iii-oni battery, through resistance 305, contacts oi cani 304.1-, outer right back contact of relay 303, lett hack contact of relay 302, lower contacts oi. earn 301, test terminal 220, hrush 221, inner right contact oit relay hirgh and low resistance windings of relay 222 to 4ground, through the windingr ot relay 216. Duc to the inclusion olE the high resistance left winding' ot relay relay 216 does not receive slzu'liicient current to'operate in this circuit but relay 222 energizesn short circuitinp; ils hie-h resistance winding, thereby chanoinel the potential upon multiples of terminal 22() to niark the selected dis -ict as .eusy to other line switches having access thereto and reducing,V the resistance ot the test circuit to such an extent vas to perinit the oiieration'of relay 216. Relay 216, upon operating', opens the circuit of niagrnet 212 which, in turn, opens the circuit ot rotary magnet 21.8 and stops the rotation oi the brushes of the switch 250. [it its front contact, relay 216 also establishes a circuit for the cult-oit relay 214iA which may he traced l'roin battery, through the winding` o'lf relay 2141, the l'ront contact of relay 216,y thence to ground at the outer lett Contact of relay 211U Relay 214:, in attractingits outer right contact, opens the circuit oi" magnet 212 at a second point. Relay 214 also loelrs itself under the control oft relay 21.1 in a circuit eX- tend' rf from battery threuejh its winding', the outer rin'ht contact of relay 211 to n'round over the inner rieght contact of relay fl. At its two outer lett contacts relay 214 connects conductors 200 and 201 extending; to the tip and rinobrushes 298 and 245 respectively of switch 250 to contacts ot relay 22S L.For the purpose to he explained hereinllelay 214 at its inner lett contact establishes a circuit tor eneraizine the sleeve relay 303 o'l the selected district selector, which may he traced from battery. through the windine of sleeve relay terminal 275, brush 241 to around at the inner lett conta et of relay 214i. Relay 303 upon operatine disconnects battery 305 freni the test terminal 22() by openina' its outer right back contact, thus marking the district selector lt will he assumed that the district sc-l busy to all line switches havingaccess thereto. lhe reinoyal of battery potential from the terminal 220 also causes the release of relays 216 and 2-22.

At its inner right 'liront contact, relay 303 -clfstahlishes a circuit tor relay 307 which y he tVl ered liroin battery through the lett ninding oit relay lll/, the lett contacts ot cani ll to ground at the inner right liront contact of relay S03. Relay 307( upon energizing; closes a circuit ttor advancing sequence switch 31.0 out oi its norinal position 1 tinto position 2. This circuit entends from battery, through the n'iagnet winding of sequence switch 310, the upper lett contact of cani 324, the outer left front contact of relay 307 to ground at the right Contact oi cani $308. As soon the sequence switch leaves position 1, the original energizing circuit of relay 30'? is opened at the upper left cen- 'l'act oit cani 30G but relay 307 is maintained energized this time over a locking` circuit extending' through its right winding, right :liront Contact, the lower right and upper lett contacts of cani 230i) to ground. TWith sequen ce switch 31() in position 2 and relay B07 energized, a, circuit is established for starting the hru'itinpT increment of the eender selector switch 325 in search of an idle central office sender. rllhe switch starts through the operation oi stop magnet 311 over a circuit extending :trein battery through its winding, the back contact of relay 315, the left contacts ot earn 308, thence to ground through the inner right liront contact of relay 303. Magnet 311, upon energizing, closes an obvious circuit for the rotary magnet 812 or" the switch the switch 325 being advanced only if its test hrush 313 engages a test terniinal upon which Jfull battery potential is encountered. All idle senders are marked by tull battery potential on the multiple test Vterminals thereoic appearingl in the banks ot all sender selector switches. lt will be assuincd that the sender shown in lille'. 4 is the first idle sender encountered. lhen, therefore, hrush engages terminal 517 a circuit is established troni battery through the back Contact of relay 4100, terminal 317, brush .313, both windings ot relay 314, winding` et relay 315 to ground, through the lower Contact of cani 316. Relay 314 energizes in this circuit but relay 315 doves not energize due to the inclusion of the high resista ce ripjht winding of relay 31aL in series therewith. lis soon, however, as relay 31e enerfrizes, it short-circuits its own right windiireg, thereby changing; the potential on the multiples ol test terminal 317 for marking; the selected sender as busy to all sender selectors having' access thereto, and permitting; sucient current to flow through the winding oit relay to cause its energization. lllith relay 3 energized, the circuit of stop magnet- 311 is opened, whereupon lll/5 the circuit of rotary magnet 312 is opened and the brushes oi the sender selector thereby brought to rest. At its front contact, relay 315 also establishes a circuit for relay 31S which may be traced from battery through resistance 305, winding of relay 818, .trout contact ot relay 315, lett contacts of cam 308 to ground at the inner right contact oit relay 303. Relay 318 upon venergizing loclrs over its innermost right contact and the inner leit contact of relay 4319 to ground at the inner right front contact ot relay 303. At its intermediate right armature contacts, relay 31S prepa .es the fundamental circuit over brushes 320 and 327. At s lett iront contact, relay establishes a circuit for advancing sequence switch 310 out of position 2 and into position 3. This circuit may be traced from battery, through the winding of sequence switch 310, the lower right and upper lett contact-s ot cam 320 to ground at the lett trout contact of relayV 318. As soon as sequence switch 310 leaves position 2, the holding circuit otu relay 307 is opened at the lower ri lgjht contact of cam 309, and relay 307 thereupon deenereizes.

With sequence switch 53.10 in position 3 and relay 31S energized, a circuit is established l`or relay 402 ot .the selected sender and relays 302 and 323 of the district selector. This circuit may be traced trom battery, tbroi the upper right and lor cam 321 and in parallel t the winding ot re l a02 and :oe 4lower contacts cit cani thence over tno outer ght Contact ct relay 318, brush 322, left back cont i of relay 401, in rrnediate and lett windings of relay 402 to groufid. Relay being marginal does not operate in this circuit but relays 302 and 402 operate, relay 302 being tunctionless at this time. Upon the operation ot ..relay 402, an ol vious circuit is cstabliened tor relay 400 which at its contact removes battery i ,al troin the multiples ot, test 317, thereby terminal inariing the selected sender busy to all the sender selectors having access thereto. Relay 402 also closs e circuit parallel with the circuit for relay 400 eu ing over brush 405 the unal ot the h which it is Tough the winding or relay 403 and to batteryY "lirough the inner ormai c-fmtacl oath e* cstabl.

in this circuit., a ci for relay 400 which may be 'traced battery, through the winding this relay, the brush 407' and normal vtei .-al oi1 the banlr with which it is associated, they right contact of relay 403 to ground the outer lett iront contact of relay 40 Relay 406 energizes closing` a circuit Ytrein ground, through the outer lett front contact of relay 404, the right contact of relay 408, the brush 407, inner left contact of relay 406, to ba-t tery, through the back contact and winding ot stepping magnet 408. The stepping magnet- 408 thereupon energizcs advancing lthe brushes ot tbe switch 450 troni their normal position terminals, whereupon the circuit of relay 400 is opened at brush 407 aud relay 400 decnergizes opening the circuit oit inagnet 408 arresting the movement of the switch.

Upon the energization ot relays 404 and 40?, a circuitwas also established 'from ground over the ,outer left front contact ot relay 404, the right contact ot relay 403, the inner left contact of relay 404, conductor 409, brush 32S, the lower right and upper ett contacts ot cam vi329, the intermediate back contact of relay '3530, terminal 231, brush 298 ot line switch 250, the outer lett contact of relay 214, the outer left contact oi? relay 228 to battery .through the winding ot relay 227. lilith relay 227 energized, a circuit is established tor relay 120 which may he traced 'from battery,` through vthc winding ot relay `120, coiullu-.tor 'lil-l, the outer left contact of relay 227 to ground `at the inner lett contact of relay 211. Relay 120 energizes in this circuit, disconnecting the negative pole of high voltage battery 1137 from the circuit previously traced, through relays 124 and 130, connecting in place 'thereof the positive pole ot battery 138. Current now flows through the winding .ot relay 130 in such a Vdirection as to cause its energization, whereupon resistance element '181 is connected to the sleeve contact of jac'lr 121 in parallel with the windings ot relays 101 and 100, thereby reducing 4the resistance of the sleeve circuit to such an extent as to cause marginal relay 103 in the operators cord circuit to operate and complete the circuit of supervisory lamp 106. Lamp 10G thereupon illuminates. The illumination ot lamp 100 at this time indicates to the operator that she may proceed to dial. The reduction vot the resistance in the sleeve circuit does not aiiect relay 101 which remains operated.

At the time relay 404 of the sender energized, it locked itself up, the circuit extending through its winding, its inner right front contact to ground at the 'left contact ot relay 402, which circuit maintains -relay 404 energized after switch 405 leaves position 1 and opens the initial energizing circuit of re lays 404 and 403. Relay 403, however, de-

energizes as soon following the advance of- CII tion il, a dialing circuit was established eX- tending troni battery, through the Winding ot the impulse relay 410 of the sender, over conductor 41.1, hrush 331, the lett contacts ot cam 332, the lower back contact of relay 530, terminal 232, brush 245,*the intermediate left contact of relay 214, the inner lett contact of relay 228, conductor 140, the lett front contact of relay 119, the back contact ot relay 123 to ground at the contact of relay 124. Relay 410 energizes in this circuit. To insure that relay 410, upon being` energized, is not disturbed during the period iinniediately elapsing after the seizure olf the sender due to disturbances in the toll line, relay 410 is held energized in a local circuit extending through its Winding, the right winding oli relay 412 and to ground at the lett Contact o1 relay 403. This `local circuit is, however, opened as soon as the dialing signal is initiated and relay 403 decoines deenergized. Upon the energization ol relay 410, an obvious circuit 'is prepared 'tor the slow releasing relay 413. .l'lelay 413 in turn prepares an obvious ciriui l'or relay 414. lilith relays 413 and 414 both energized, the stepping magnet 417 of the lrst Code register in placed under the control of the impulse relay 410.

.ln response to the illumination oit lamp 106,l the operator at position 125 actuates the dial lacy 105, thereby removing the supervisory equipment ol.1 the cord circuit 'trein` the sleeve conductor thereot and causing lamp 100 to he extinguisl'ied. Relay 101 is new maintained operated from battery associated with the dial 107.

The operator non' actuates the dial 10T in accordance with the first digit et the numher ot the desired line.. this c u 1' the first code letter of the otlice designation. llelay 101 nonT 'tollons the interruptions ot the dial contacts to intern'iittently connect and disconnect ground from the composite leg ot' the toll line 150, whereupon relay 124 is intermittently energized and deenergized. 'llic intermittent operation ol' relay caw ground to be intermittently applied to the conductor 140, the circuit extending l'roin ground at the contact of relay 124, the

haelt Contact ot relay 123, the lett tif-ont contact of relay 119, conductor 140, the inner lett Contact of relay 22S, the intermediate le'i` Contact of relay 214, conductor 201, hrnsh 245, terminal 232, the lower baclr contact et relay 330, the lett contacts or" cani i332, brush 331, conductor 411 to battery, through the Winding ot impulse relay 410. This impulse relay thereupon follows the interruptions ot the dial contacts and eilects the setting ol" the A code register.

llpon the first deenergization of relay 410, a circuit is established from ground at its back Contact over the lett trent Contact of relay 413, Winding ot relay 415, brush 416 of the steering switch and the normal terminal upon which it is standing, the contact and Winding ot stepping magnet 417 tor battei-y, through the lett Winding of ott-normal relay 418. Magnet 417 and otl-norinal relay 418 energize in this circiuit, relay 418 connecting ground over its contact to the oltnornial conductor 432 lor holding the relays 400 and 404 energized independently or' relay 402. telay 415 also energizes in the circuit ot magnet 417 and at its armature and iront Contact closes a circuit through the magnet winding 421 o12 the steering switch 425 preparatory to advancing the steering switch upon the termination of the lirst series olf impulses. A second circuit is also established at this time :tor relay 420 which may he traced from battery, the Winding ot' relay 420, the inner right Contact ot relay 41.11, brush 419 and the normal terminal upon which it is standing, the armature and back Contact oli magnet 417, the normal terminal and ln'iiisl'i 416 oli switch 425, thence as traced, through the Winding ot relay 415 to ground at the bach contact ot relay 410. Relay 420 ener` izes in this circuit and at its right contact connects ground directly to the winding olf relay 413 fo insure that that relay Will remain energized nntil 'the pping magnet 417 has coinpleted its stroke. it its lett contact, relay 420 loclts np and connect-s, ground to one terminal of relay 415 for maintaining the relay 415, energized irrespective oi' the eontined deenergization of relay 410. As soon magnet 417 completes its forward stroke, the circuit of relay 420 is opened and the holding circuits ot relay 413 and relay 415 are opened. Thus, the complete energization of magnet 417 is insured regardless ot the period that relay 410 remains deenergized. lllhen the stepping magnet 410 anain energizes, the circuit previously traced io relay 415 and magnet 41? is opened and magnet 41'? deenergizes, advancing the irst code register one step. Stepping relay 415. honorer, being` slonv to release does not have time to retract its armature during the brief periods during which relay 410 is deene eized. Thus, in response to each deene lization and energization ot relay 410, magnet 41? advances the A code register one step.

ll pon the tern'iination oi the first series ot impulses, relay 410 remains energized for a sui'licient time to permit relay 415 to retract itnre7 y-rherenpon the circuit ot' magnet ot the steering switch is opened and the rin switch advances its brushes one step. lilith the steering switch in position 1, inagnet 422 is operated in response to the operation oi iinpuhe relay 410 for advancing the brushes oit the B code register to positions Corresponding -to the digit Value ot the seeond code digit dialed. Following the dialing r the code digits ot the desired line, the toll operator dials the numerical digits, where upon the numerical registers, not shown, ol-l the sender are operated to register the 11u-- inerical designations ol' the desired line. Following the registration ot the complete line designation, the translator switch, not shown, is set in accordance with the combined set tings ot the A and registers in the manner fully set iiorth in the patent to G. ll. Kopp hereinhetore referred to, and the circuits ot the sender are prepared for controlling the setting et auton'iatic switches to extend the connection to the terminals oit the desired liao, n the preparation oi? the sender cir- "i e sequence switch thereof, camz-i olf e illustrated in the upper portion ol' advanced out ot its normal position ection mfnfeinent. ,it vwill heA recalled that the 3l0 ot the district selector 3:"0 was sequence switch advanced following the select on ot the i L 4, J: f N, n sender and, cheieiore, with the seipieuce to position 3 switch et the sender in position 2, a {undasiental switch controlling circuit is established between the circuits 01"' the district selector and th sender wh'ch may he traced trom cattery through the right winding o'i relay 30T, the lower contacts ot' earn contact 350 ot relay 313, brush 327, the right haelt contact ot advance re lOl, the windings of the sender steirpinpa relay l30, the back Contact of relay 423, contact ot cam 427, winding or' polarized overilow relay 24; to ground through the lett contacts team Relays 30T and 30 energize in this circuit but relay 421i being polarized does not receive current of the right polarity to cause its operation. Relay e30 upon energizing closes a circuit, not shown, in the well-known inanner for associating a` proper pair ot counting' relays with contacts ot the translator switch for controlling` district brush selection.

At the district selector, relay 307 upon energizing` closes a circuit tor advancing sequence switch 310 out ot position 3 into position which circuit he traced 'from battery, through the mi L lt winding the sequence switch, the uoper lett contact ot cam 324:, the outer lett iront contact ol relay 307 to ground the right cont ct of cam 308. As soon as the sequence switch advances out of position the initial energizing circuit oi relay 30? previously traced is opened at the lower left contact ot cam 333, but relay 30'? is maintained energized in series with the stepping relay 4:30 over a circuit which may now be traced trom battery, through the right winding and right front contact of relay 307, the upper lett and lower right contacts ot cam 333, and thence over the circuit traced to ground, at the lower left contact of cam 426. lVith relay 307 energized and sequence switch 310 in position 4i, a circuit is established for the up- 'e magnet oi' the switch 350 for advancing the switch shat't in its 1ore-.sh selecu A' nioven'ient. lllhis circuit may be traced from battery, through the winding ot magnet the lower right contact ot cam 335, the outer lett iront contact or relay 307 to ground at the right Contact ot cam 303. As the switch shaft advances in its brush selection movement, the coinmutator brush 333 engages segn'ients oi coinmutator strip 337, whereupon a circuit is intermittently estahlished in shunt ot the windings o' stepping relay Li230 which may he traced trom battery, thrriugh the right winding ot relay 307, right viront c( act ot this relay, the upper left contact of cam 333, the upper right contact am 330, coniniutator strip 337, brush 33S 'lo grrnurd, at the upper lett contact ot cani 339. Relay 30?- is maintained energized over this shunt hut relay 130 denergizes each time that the brush 333 enggcs a conducting portion of the strip 33T coi, responding to a brush tripping position.

response to the intermittent operation et relay le30, counting relays of the sender operate .successively in pairs in the welllnc'wn manner until the 0 countirg relay i energizes in parallel with relay 423, the operated counting relays locking to ground o er the contacts oit cam l lWith relays 43' and energized, relay 423 opens the fundamental switch controlling circuit previously traced and relay i establishes a circuit in stell-humm manner tor advancingg the sender sequence switch out ot position 2 into position s soon as the ,equence switch larves position 2, the operated counting relays released through the opening of the contacts ot cam 420. The circuits olf the entier are now in condition for controlling 'the group selection movement ot the district selector 350.

At the districtselector, upon the opening u 'i n or he Iundaincntal cn cuit, relay o0! deenerbrush 3" engages the gizes as soon as the ooo next insulating segment ot the commutator strip 33'? and at its outer lett bach contact establishes a circuit tor advancing sequel-'ice s "itch 310 out of position l into position This circuit may be traced trom battery, through the magnet winding ot sequence switch 3l0, the lower left contact ot cam 32st, the outer lett back contact ot relay 30T to ground at the right contact oit cam 303. llith the sequence switch in position and sequence switch 310 of the district selector in position the previously traced fundamental switch controlling circuit is again established through the windings ot sender steprelay Zi3() and the right winding of re- 07. Relay 307 again energizes. closing the previously traced locking circuit lor itself over the upper left and lower right contacts of cam 333 and advances sequehce Melrose switch 310 into position 6. As sequence switch 3l() advances troni position 5 into position (i, an obvious circuit is closed tor the trip magnet 3&3, extending over the lower right contact oi cani 339 for energiaiiigl the trip magnet 343 for tripping the selected set oi brushes upon the next subsequent upward movement oi' the switch shaft.

VVith sequence switch 310 in position 6 and relay 307 energized, the previously traced circuit for the lip-drive magnet is again established and the switch shaft is driven upwardly. During the lirst portion ot this upward movement, the selected set oi? brusl'ies is tripped through the operation oi magnet Sii-$3 in the well-known manner, and thereailter the tripped set ot brushes advances in contact with the terminals oit its associated bank. During,l the continued upward niove nient oi the switch shaft, the brush 34:1 encjau'es the ooinnuitator strip 340 for intermittently shunting the stepping relay i230 ot ille sonder each time that the selected set ot brushes ap proaches the bottoni ot' the groups oi' bank terminals. This shunt circuit may be traced, iroin battery, through the right winding,Y a nd right front contact of relay 30T, the upper contacts of cani 33S, conunutator strip 340, hrush 341 to ground at the upper lett contact of cani 839. Relay 307 is inaintained energized over lthis shunt path but relay 340 deenerg'izes each time that the brush 234-1 encounters a conducting portion of the strip Sli() and in the well-known inanner causes the successive energization ot pairs ot countinj relays. rihe opel counting are again locked over soon as the distr the counting` relay Si euere in parallel with relay 42th the relay -i`i roaring 'the sender sequeinre :iurilch into position (l, releasing` the operated counting` relays and preparing the circuits ci the si. i ilor incoming; brush selection. and opcisingr the iurdauieutal switch con. o circuit previously raced.

its soon ifollowing; the opening;v oi the tundainenlal circuit as the brush Seti engages the next insulating' segment oit cominutator strip 34M), relay 307 denergiaes opening' the circuit oit the up-drive magnet 539i and closiuf; the previously traced circuit Ltr adriano iuuj the sequence switch 8l() out ot' posi'ion (i into position i". The selected set ot' brushes has now been positioned in engagement with the lower-most set oit terminals in a desired group oft its bank.

With sequence switch 310 in position "i", relay 307 is energized in a circuit which may be traced troni battery through its lett winding, the lett contacts ot cani 306 to ,orotuid at the inner right contact ot relay 53053 and at its outer lett 'front contact closes the previously traced circuit tor advancing' sequence switch 310 out ot position i into position 8. ris the sequencl switch leaves position 7%, the previously traced operat ing circuit ot relay -)Gi opened at the ipper lett contact ot cani 306 but it, however. the trunk terniinating in the i'irst setot terminals, upon which the brushes are resting. is at the time busy, as will be assumed, relay T remains energized over a locking; circuit which may be traced troni battery through its right winding and inner lett contact, the lower contacts ot cani 309, overiiow seg. rout 534-9, 'wiper 35i, test brush 2542 to ground on the test terniinal ot' such lirst busy trunk. idhen, therefore, sequence switch Si() reaches position t, since relay 30T energized, the previously traced circuit ot the up-drivc magnet 33st is established and the switch shaiit is driven upwardly iu a trunk hunting inoveinent. loupl as the brush M2 encounters busy `around polential on the test tcrniinais oi' the truulrs over which it passes, relay l will be iuaintained energized and the circuit oi the updrive magnet will remain closed. ile/heu, however, the iirst idle truulr is encountered, having no ground potential upon the test terminal thereof, the locking?,` circuit or' relay 307 is destroyed and re.,.y 30? thereupon decnergizes ooening the circuit ot up-drive magnet 3B/le and closing4 the previously traced circuit for advancingl sequence switch 3l() out ot position t into position 9.

As soon as relay 30's" deenergizes, i l ground potential is connected over t' e test brush 342 to the test te aninal the selected trunk over the brush 35i, the oyerliow strip {Ji-i9 of the coinlnutator, the lo ver contacts ont cani 309, the right back Contact ot relay 30T to ground at the upper lett contact o t cani 35T. ritter sequence switch 310 reaches n sition ground potential connected t the brush over brush 551 and strip of and the lett contacts ot Cain 539 independently ot relay 307.

is soon the sequence switch reaches position 9, a circuit is established tor rcenergizing relay 30T, which circuit battery, through the left winen 807, the lower contacts ot u oiE rc i. cani fico, the riggl contact ot relay 302, this relay haring energized, as will be recalled, immediately upon the seizure oi.t the sender, thence over the innermost lower baclr contact ot relay to ground at the upper right contact ot cani 839. As soon as relay 30?' energize the previously traced circuit is established tor advancing` sequence switch 2310 into positionl l0, in which position the indainei:

switch controlling circuit is e. iid-cd Afrom the sender to the control relay ot' he lected incoming` selector (350. This circu: rmay be traced from battery, through the ilt! left winding of relay 605, the Aupper contacts of cani GGS), the lowe right contact of cani 615, the upper lett contact of am SO-i3, concontact 356 of relay 818, hrusi right back contact ot advance relay windings of sender stepping rela f back Contact or relay 428, Contact oi" and winding oi overflow relay i2/l, upper left and lower right contacts oi cani 426, brush 320, the nent to outer right coetact of relav7 318, the lower lei't and Aupper right contacts ot cani the lower bail; contact olf relay 353, brush 34:5, conductors 502 and .305 to ground, through the lower contacts ot cam (50T. wtelays ($05 and All-0 energize in this circuit, polarized relay not receiving current in the proper Y tion to cause its energisiatioii. Relayy i550 upon energizing prepares a circui in the well-known manner lfroni the thousands register olf the sender to the couiitin controlling the incon'iing selectoi brush selection movement.

lele-y (305 upon encrifine ductors 504 and 50i, brush 345, Jhe appermost hack contact oit re ay 352:3, the upper right and lower lei'rt contacts ot cai iii its 61,2, to battery through the maw or sequence switch Gil) 'lor a lv vicing the sequence switch out ot position l and into position 2, wlierea circuitis closed for the rip-drive magnet 61S. This circuit may he traced ifrom battery, through the winding or' magnet G18, the lower right Contact cam 612 to ground at the rigiit front contact or' relay 605. ln position 2 ot sequence switch 6l relay is maintained energized in a circuit from battery through its left front Contact and the lower right contact olf cani 615, thence over the lundamental circuit ground at cani 601'" as described.

rlhe rip-drive magnet G18 causes the brush shaiit or the selector to nieve up vardly and tor each brush tripping position passed over to close a circuit for slinnting the sender stepping relay L80 while maintaining relay G05 operated. rhis circuit n'iay he traced Ytroni battery, through the lett winding and lett iront cortact et relay lower contacts et cani 515, cemmutator strip G30. h ush G28, to ground at the lower lett contact et cani G13. The stepping relay 4:30 is deenergized each time the above traced shunt circu't is closed and couiting relays of the sender are operated. This operation continues unt-il the O couniing relay Si energizes in parallel with relay 28 when the sender sequence switch is advan `ed out ot position 6 into position 8. unlocking the counting relays and preparing the solider circuits 'for incoming group selection, and the fundanienal circuit is opened. As soon following the opening of the fundamental the ci i'cr deci Mtb cani till to batsequence switch switch 2 into poen ot seoucnce switch G10, and

' sequence switch7 the last traced is again in energize, relay e3() prothe hundreds and ays in the well-known iper. energizing again vraced circuit over its Y ior advancing sequence iosition fl, relay 605 being .ic '.;e=l over the lundaiiieiital itioii e ol the sequence switch previously describe l and coinrcuit previously traced for the friet (S18, drivingthe switch ly in its group selecting movet`ic sequence switch 610 passed stlon into position l, a circuit the lower contacts of cani 614i gnet G19 so that, during the 'it t ie group selecting move- 'witcli shalt, a set et brishes to engagement with the of the bank associated ach group oi'l terminals "ppcd set oi brushes, a ni battery, through the lett liront Contact ot' relay 'eht c itact ot cam 615, the i (30S, coniniutator st- 'Y s 3:2? to ground at the lower lett Contact oY cani G18 The closure oit this ci: enit holes rela.'v 505 energized and shunts the stepnine re ay of the sender.

n? 1 I ie sen-"ler nas hecoine satisfied, the 3l energises in parallel switch 610 into position 5. The selected set ot brushes G21, 622 and GAS have now heen positioned in engagement with the lowermost set of terminals of its associated bank.

In position 5 ot sequence switch 610 a circuit is closed from battery, through the rightwinding of relay 605 to ground through the right contacts ot cam 63st. Relay 605 operates and loclrs in the following circuit provided the first trunk in the group, upon the terminals of which the brushes 621, 622 and 623 are outstanding, is busy. This circuit extends from battery through the lett winding and left front contact ot relay 605, upper contacts of cam 6141, brush 623 to the grounded test terminal 0'1": the busy trunk. Relay 605 at its right front contact closes a circuit over the lower lett contact or' cani 612 to drive sequence switch 610 into position 6. Relay 605 remains ene1 gized in this position and completes a circuit trom its right front contact, the lower right contact of cam 612 to battery through the winding ot up-drive magnet 618. The brush shaft is driven upwardly to move the brushes 621, 622 and 623 over the terminals ol the group in search or an idle trunk. lhen the first idle trunk is reached, no ground potential is present upon the test terminal thereorIl and the holding circuit or' relay 605 is opened. This relay, however, remains energized for an instant by means of a oircuit from battery through the right winding oli said relay, lower right and upper lett contacts of cam 634, commutator strip 632, brush 620, the upper Contact of cam 618 to ground at the right front Contact oit relay 605 to insure that the movement ot the brush shait will continue until the brushes are properly centered upon the terminals of the idle trunk. l/Vhen the brush 629 engages the next insulating` segment of strip 632, relay 605 is deenergized and the circuit et magnet 618 is opened causing the brush shatt to cease its upward movement. Relay 605 at its right back contact closes a circuit extending over the lower lett Contact ol" cani (lll ter advancing sequence switch 6i() out ot position 6 into position 7.

In position 7 ot ,sequence switch 610. a circuit is closed from battery, through the lett winding ot relay 605, upper contacts ot cam 600, lower contact of Cam 616, brush 622, trunk conductor 625, upper lett and lower right contacts of cam 705 toground at the lower lett contact oft cam 706. Relay 605 becomes energized and closes the circuit through its right iront contact for driving sequence switch 610 out of position 7 into position 8. lVhile sequence switch 610 is moving out oit position 7 and into position 8, relay 605 is maintained energized over its lett winding and left front contact, lower contact olf cam 616 to ground as traced.

'lhe trunk (32e/l and 625 selected by the incoming switch is held busy so as to be non-selectable by other switches by means of ground potential placed on the test conductor 626, over a circuit extending from ground, through th-e right contacts of cam 614, test brush 623, and thence to the multiple terminals of the test conductor 626.

The fundamental switch controlling circuit tor controlling the selecting movements of the linal selector switch 750 is now completed and may be traced from battery through the right winding of relay 700, the lower left contact of cam 7 03, the lower lett contact of cam 702, conductor 62st, brush 621, the right contact of cam 617, conductors a and 501, thence as traced Vthrough the sender returning over conductors 502 and 505, the upper contact of cam 612 to ground at the right front contact of relay 605. Relay 700 energizes and closes a circuit for relay 721 which may be traced trom battery through the lett winding of this relay, upper left contact of cam 707, left front contact of relay 700 to ground at the upper Contact ol cam 708. Relay 721 energizes in this circuit and at its lett front contact closes a locking circuit for itseliC extending from battery through its left winding, back contact of relay 724, left liront contact of relay 721 to ground on conductor 626. Relay 721 upon energizing closes a circuit extending from ground at its right front contact over the lower contacts of cam 709 to battery through the magnet winding of sequence switch 710 for ad vancing sequence switch 710 into position 2. llihen sequence switch 710 moves out of positionl, the initial energizing circuit of relay 700 is opened at the lower contact of cam 7 08, the relay 700 remaining energized over the fundan'iental circuit by reason of a locking circuit extending from battery, through its right winding, lower contact of cam 740, the right contact ot relay 700, the lower right contact of cam 703, thence to ground over the fundamental circuit as previously traced. Relay 700 upon energizing, with sequence switch 710 in position 2, closes a circuit for the high `speed 'up-drive magnet 726, cxtendingiirom battery, through the winding ot' magnet 726, the upper right contact or cani 711, the lett front Vcontact or' relay 700 to ground at the upper contact ot' cam 708. Magnet 726 upon energizing advances the switch shaft ot the final selector in its brush selection movement.

As the switch shaft approaches each brush selection position, the brush 736 ena conducting portion of commutator strip 730, thereby establishing a shunt around the windings of .stepping relay 430 of the sender while maintaining relay 700 energized. This shunt circuit may be traced from battery through the right winding of relay 700, the lower contact of cam 7 40, the right front contact of relay 700, the lower right contact et cam 703, the upper right llt) `ILO

contact ot cani 702, commutator strip 7 30, brush 736, the right contact otl cam 707, the lett front contact of'relay 700 to ground at the upper contact of cam S. As soon as the sen-der is satisfied with respect to its iinal brush registration, the sender sequence switch advances previously described and the fundamental circuit is opened. As soon atter the opening ot the fundamental circuit as brush 736 engages the next'nsulating portion ot commutator strip 730, the holding circuit ot relay 700 is opened and relay 700 deenergizes. As soon as relay 700 ret acts its armature,` the circuit oi' the updrive magnet 720 is opened and a circuit is established from ground at the upper contact oit cani 708, 'the leit back contact of relay 700, the lower right contact ot cam 712 to battery through the magnet winding et sequence switch 710 for advancing the sequence switch 710 linto position 3. With the sequence switch in position 3, a circuit is closed from ground at the lower right contact oit cam 706, through the winding oi trip magnet 7 35 for rotating the tri-p spindie preparatory to tripping the selected set ot' brushes.

,'Vhen sequence switch "l0 reaches position 3, the energizing circuit ot relay 700 and of the stepping relay of the solider is again established. Relay 700 again establsnei the previously traced circuit tor advancing sequence switch 7l0 out of position l into position il. ln position er, the circuit out the rip-drive magnet 72b is again established previously traced for advancing the switch shaft in its group or `tens selection movement. Als the switch shaft advances through the initial portion ot its group se lection movement, the selected set of brushesV is tripped in the Well-lniown manner. As the switch shaft approaches its lirst group selection posit-ion, the brush 7 3S engages the lo\.\'ermost conducting portion ot `he comiiiutator strip 737 and a circuit is closed in shunt ot the stepping relay ot the sender and may be traced from battery through the nt winding ot relay 700, the lower contact o't cani 740, the right front contact oi relay 700, the right contacts cam 703, commuq tator strip 737, brush 738, and thence as traced to ground at the upper contact of cam 708. As the switch shatt advances, the sender stepping relay is intermittently shunted 'until the sender is satisfied with respectto the setting ot' its tens register when the sequence. switch of the sender is advance-'jl and the 'tundamental circuit is ed in the well-known manner. As soon, nierea'tter, as the brush 73S engages the next in portion oi the coinmu'tator strip 737, relay 700 deenergirfzes opening the circu et the up-drive magnet 726 and closing the previously traced circuit over the lower right contact o1" cam 712 for advancing scquence switch 7 i() into position 5.

In position 5, the fundamental circuit is again established and relay 700 energizes advancing sequence switch 710 into position G. With relay 700 energized and .sequence switch 710 in position (E, a circuit is estab lished for the low speed lip-drive magnet 739, extending from battery through the winding of this magnet, the lower lett con tact ot cam 707, the lett iront contact ot relay 700 to ground at the upper contact oil cam 7 08. Magnet 730, upon energizing, advances the switch shaftt in its units selection movement. During this movement oit the switch shaft, an intermittent shunt is established which may be traced Atroni battery` through the right winding of relay 700, the lower contact of cain Titti', the right iront contact oi' relay 700, the lower right contact oiI cam 703, the upper right contact et cani 762, connnu'lator strip 730, brush 73o, thence as tr ced to ground at the upper contact ot cam 70S. Relay 700 is maintained energized in this shunt circuit but the sender stepping relay is intermittently decnergized until the sender is satisfied with respect to its units registration when the fundamental circuit is opened at the sender. fis soon thereafter as the brush 73' engages the nent in sulated portion ot commutator strip 7230, relay 700 deenergizes, opening the circuit of the rip-drive magnet 73 and closing the previously traced circuit lor driving the sequence switch 71.0 out ot position and into posi-tion 9. The brushes 752, and 7 are now positioned upon the terminals of the desired line and the final selector thereupon proceeds in the usual manner to test the line iter its busy or idle condition. Assuming 'that the line is found to be idle, the sequence switch 710 is advanced through intermediate positions from the position i) into the talking position l5, in which position Jihe talking {rcuit is extended troni conductors (S24 and over the lower contacts ot' cam 702, the upper contacts of cani 705, and brushes 752 and 752-3 to the conductors of the called line.

lllh'en sequence switch 710 leaves position 8% the circuit hereinbe'lfore t"aced for relay G05 is opened at the lower lett contact of cam 706 and relay 605 thereupon deenergizes. Relay @05 upon deenergizing closes a circuit from ground at its right back con-- tact over the lower lett contact ot cam (ill for advancii'ig sequence switch 610 out ot position 8 into position 9. Vith sequence switch 610 in position 9, relay 605 is con nccted in a circuit extending irom battery, through its lett winding, the right contacts of cani G09, conductors 505 and 502, 'thence traced to the sender, through the windings oi sender stepping relay 430 and the Ill) winding oi polarized relay 424, returning` over conductors 501 and 504, the upper left contact ot' cani 60G to ground at the upper lett contact of cani G15. Relays 605, 430 und 424 energize in this circuit, as the currentnow tlows in the proper direction to energize the polarized relay 424. Relay 005 upon energizing closes a circuit over its right liront contact for advancing sequence switch 010 troni position 9 into position 11, As the sequence switch is passing troni poion 9 into position l1, relay 037 is energized over the lower contact or cani 041 ttor the purpose of opening the ringing control circuit and to disconnect ground troni the tip conductor .504 o't' the trunk circuit. Upon reaching position 11 relay 005 is energized i'roin ground on conductor 503, over cani 003, the lower lett and upper right contacts ot cani 609 to battery through the lett winding of relay 605. Relay 605 upon energling locks over its lett armature to ground through the upper left and lower right contacts of cani 614 and advances sequence switch 610 into position 13. After the sequence switch leaves position 11%, relay G is maintained locked over its leilit contact and the le't't contacts of cani G00.

At the sender, upon the operation of the polarized relay 424, an obvious circuit is closed for relay 401 which opens the fundamental circuit and at its lett contact opens the shunt around the right winding of relay 402. The current now flowing through the windings of relay 402 over the circuit previously traced to battery through the winding ot' marginal relay 302 is now decreased to such an extent that relay 302 deenergizes opening the holding` circuit ot relay 307 eX- tending through the right front contact ot' relay 302, whereupon relay 307 deenern'izes. lli/'ith relay 307 deenergized, av circuit is now closed tor advancing sequence switch 310 out ot position into position ll, which circuit inay be traced Atroni buttery through the winding ot sequence switch inagnet 310, the lower lett contact ot cani 324, the outer lett bach Contact ot relay 307' to grouiid at the right contact of cain 308. lith sequence switch 310 in position 11, a circuit is establish-ed :tor the relay 330 extending` frein battery` through the lower winding` ot this relay, the upper right and lower lelt contacts olE cani 358 to ground, through the lett tront contact of relay 313, thus opening the tip and ring leads ot the district link and disconnecting the winding of supervisory relay 359 during the talking select-ion operation ot the district selector 350.

A circuit is also established at this tiine ilor relay 307 which may be traced troni battery, through its right winding, the lower contacts ot carn 333, contact 350 ot relay 318, brush 327, the back contact ot relay 401, winding of stepping relay 430, the back trat-ion ot the translator contact ot relay 423, the contact ot cain 427, now closed in position 16, the winding of relay 424 to ground, over the lett contacts of cam 426. Relays 307 and 430 energize in this circuit, relay 307 closing a circuit over the upper left Contact of cani 324, the outer lett front contact ot relay 3l7 to ground at the right contact of cani 308 for advancing sequence switch 310 out ot position 11. Alfter sequence switch 310 leaves position 11, its driving circuit is maintained closed over the upper lett contact ot cain 303 to the inner right front contact ot relay 303 to insure its continued inoveincnt through successive talking' selection positions. the sequence switch continues to rotate, an intermittent shunt is placed around the windings of sender stepping relay 430, extending troni battery, through the right winding and right front Contact et relay 307 to ground, through the lower right and upper lett contacts of cani 309. Relay 307 is maintained energized over the shunt path but stepping relay 430 of the sender intermittently deenergizes, successively operating pairs of counting relays at the sender in accordance with the talking selection regisswitch otl the sender. W'hen the sender is satislied with respect to its talking sel ction registration, the undainental circuit is opened through tne operation oli' relay 423 in the well-known inanner and the circuit oit relay 307 is opened. Upon the deenergization ot relay 307, the circuit of sequence switchl magnet 310 is opened and the sequence switch cornes to rest in one ot' the talking` selection positions 12, 14 or 16, lt having been assumedv that the connection has been established to a full automatic o'tllce, the fundamental circuit is opened by the sender when the sequence switch is passing through position 1338, and therefore the sequence switch 310 is arrested in position 14. Relay 307` upon deenergizing also closes a circuit .extending tf1-oni the lett terininal ot the winding olf relay 313 over the upperniost front contact o't relay 330, the lett contacts et cani 3h0, the outer lett bach contact ot relay 307'. the upper lett contact of cani 303 to ground at the inner right contact oit relay 303, thereby shunting relay 318 and causing its deenergization. `With relay 313 deenergized, the circuit previously traced through the windings of relay 402 and the windings ot relays 302 and 323 is opened causing` the release of relay 402.

lhen sequence switch 310 advances beyond position 10, the circuit previously traced for relay 410 is opened at the lett its `cont-acts of cani 332 and relay 410 thereupon releases, in turn releasing relays 413 and 414. Relay 413 upon deenergizing establishes a circuit troni `ground at its right nornial contact over brush 435, and the terminals ot llt) the restoring bank ot the steering switch 425, back contact and Winding of stepping magnet 421 to battery through the right Winding of relay 418. Magnet 421 operates in this circuit advancing the brushes ot' the steering switch to their normal positions, the circuit of magnet 421 being interrupted at brush 425 when the brush 435 reaches normal. Relay 414 upon decnergizing estatlishes a circuit for the stepping magnet 417 ot' the A register, which may be traced from battery, through the lett Winding oi relay 418, the Winding and contact ot inagnet 41"?, terminals of the restoring bank and br sh 438 of the register to ground at the outer right back Contact o1 relay 14. he magnet 417 advances the brushes of the register to normal position in which position the brush 433 extends the restoring circuit through brush olil the B register and through the Winding of magnet 422 to battery. The magnet 422 energiiaes in this extende'L restoring circuit, restoring` the brushes or the 2 register to normal. ln a similar manner the remaining registers o the sender are restored to normal.

Upon the deenergization of relay 402, and the removal of ground from the oil-normal conductor of the sender, the holding circuit ot relay 404 is opened. This relay decnergizes, closing a circuit for relay 406 `which may be traced from battery through the windingl of this relay, brush 407 and the oitnormal terminals of the bank with which it is associated, to ground at the outer leitback contact ot' relay 404. In response to the energization of relay 406, a circuit is established from battery, through the Winding and back contact of stepping magnet 408 of the monitor switch 450, the inner left contact ot' relay 406, and thence to ground over brush 40T and the outer lett back contact of relay 404. Magnet 408 energizing in this circuit, advances the brushes ol the monitor switch troni Whaterer position they are standing in at the time into their nornral position. Upon reaching normal the circuits ot' relay 406 and magnet 408 are opened. he deenergization o'lf relay 402 also closes circuits, not shown, for restoring the remaining apparatus ot the sender to normal. Since, however, the manner in which this is accomplished does not inti mately concern 'this invention, these restoring operations will not bc furtl'ier disclosed or described herein.

Upon the advance ot sequence switch 310 ol theI district selector into position 14, relay 380 is held energized in a holding circuit extending from battery, through its lower winding, the upper contacts et' cam 358, the lowery front contact o'f relay 380, terminal 232, brush 245, the middle left contact o' relay 214, the inner left contact of relay 228, conductor 140, the left front con-tact of relay 119, thc back contact ot relay 123 to ground at the contact o1' relay 124. Thus, relay 330 is maintained energized until the toll operator receives a trunk closure signal, as Will hereinafter be described.

A circuit is noir established for the supervisory relay 859 of the district selector circuit which may be traced from battery, through the right Winding oE coil (300 at the incoming selector' of Fig. (3, the outer contact ot relay 001, lower left winding of repeating coil (539, the upper contacts ot cam 00T, conductors and 502, brush 840, the lowerinost contact of relay 2358, the upper contacts ot cam 855, winding ol relay 235i), the upper contacts ol cam 854, the uppermost back contact oll relay 558, brush 34:, conductors 501 and 504, the lower contacts or' cam (50G, the upper lett Winding olf i peating coil 680, the inner contact oif relay (501, the left winding of coil (300, to ground at the outer right contact or relay (33T. Relay 850 energizes in this circuit and as soon as interruptor 301 makes its right contact establishes a circuit for relay 802. This circuit may be traced from battery, through the winding relay the Contact of relay 359, the right contact ot interruptor 301, to ground over the upper contacts ofi lam 309. Relay 362 upon energizing locks over its inner right contact to ground at the right contact of cam 810 and establishes` a circuit for relay 228 which may be traced from battery, through the Winding of relay 228, the outer right back contact thereof, the middle right contact of relay 214, brush 288, terminal 229, the outer right contact of relay 302, to ground, at the lett back contact of relay 318.

Relay 228 upon energizing in this circuit locks over its outer right iront contact to ground'at the inner right front contact of relay 214 and at its left contacts opens the connection heretofore existing over brush 298 through the nf'inding ot relay 227, and over brush 245 to ground at the liront contact of relay 124. rlhe ren'ioval ot the ground connection from brush 245 destroysI the holding circuit of relay 330 which thereupon releases, cutting the talking conductors ol the district link through to the back contacts of the ringing relay Relay 228 also establishes a circuit tor the relay 11T extending from battery through the Winding and back contact ioll this relay, thence orer conductor 142, the inner right contact el relay 228 to ground at the inner left contact of relay 211. Relay 117 energizing in this circuit locks itself directly to ground on conductor 139 and at its right 'front contacts connects the talking conductors 200 and 201 to the tip and ring conductors of the toll line 150. Relay 227 at its outer right front contact also establishes a OP mi.

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circuit 'l'o-r the signaling relay 227 which niay be traced from battery, through the winding of this relay and the outer right front contact of relay 223, the iniddle right contact ot relay 214, brush 233, termina 229, outer right contact ot' relay 362, thence to ground at the lett back contact ot' relay 31.8. Relay 227 energizes in this circuit and establishes the previously traced circuit for relay 126, which again reverses the current ilo-wing over the composite leg ot the toll line 150 through the winding ot polarized relay 130 caufsing relay 130 to respond and in the inanner previously described, to cause the energization on". inarginal relay 103 and the lighting of the lainp 106. The lighting ot lainp 106 at this tiine signals the toll operator that the talking connection has been put through and that the automatic ringing ol the desired subscriber is proceeding.

lVhen the interrupter 361 next makes its lett contact, with relay 362 energized, a circuit is established for the ringing relay 353 which niay be traced from battery, through the winding et relay 353, the outer leitt contact ol relay 362, the lett contact ol' interrupter 361, thence to ground through the upper contacts ot cain 309. Relay 353 upon energizing establishes a ringing circuit eX- teuding to the inconiing selector which may be traced from the source ot' ringing current 363, through laiup 371, contacts ot cane 364, lower liront contact ot relay 353, brush 346, conductors 502 and 505, upper contacts of cain 607, lower lett winding of repeating coil 639, condenser 640, ringing relay 602, upper lett winding oit repeating coil 639, lower contacts ot cain 606, conductors 504 and 501, brush to ground at the upper front contact oit relay Relay 353 also opens the talking circuit extending back to the toll line 150 and closes a circuit tor relay 302 which may be traced 'from battery, through the winding ot relay 302, the inner upper 'lront contact ot relay 353, the right contacts of cani 301, to ground at the' left back contact ot relay 313. Relay 302 operates in this circuit and locks over its left trout contact through cain 301 to ground at the lett back contact ot relay 313. When the interruptor 361 next opens its lett contact, the circuit ,tor ringing relay 353 is opened, but relay 302 remains locked.

Relay 602 res bonds to the rinoino current ,f Cv P5 applied by relay 353 troni the source 363 and establishes a circuit for relay 601 extending 'troin batt-ery, through the right winding ot relay 601, the contact of relay 602, to ground at the inner right back contact ot relay 637. Relay 601 upon energizing in this circuit removes the windings ot coil 600 troni the connection previously traced to the contacts ot relay 353. A circuit is also established at this tiine for relay 642 which may be traced from ground, inner back contact oil' relay 637, contact of relay 602, back contact oit relay 662, inner lett normal contacts and winding of relay 642 to battery at the norinal inner lower contact ot' relay 604.

Relay energizes in `the circuit traced locking itself directly to ground at its inner lett front contact short circuits the lower right winding ot repeating coil 639 through its outer lett front contact, and establishes a circuit for pick-up relay 644. rlhis latter circuit inay be traced frein battery, through the winding and inner lett norlnal contacts of relay 644, right 'front contact oit relay 642 to ground through th-e right contacts ot cain 643. Relay 644 upon energizing locks over its inner left lront contact, the back contact ot relay 645, to ground at the inner back contact ol' relay 637 and also establishes a circuit from ground at its outer lett contact to battery through the winding of ringing relay 604.k Relay 604 upon energizing closes a circuit tor alternately applying ringing current troni source 649 to the called line. This circuit niay be traced from the ringing source 649 through the interrupter 643 or battery, through the interrupter 647, over the right Contact oit' cani 646, ringing cutott relay 645, inner right trout contact of relay 644, lower tront contact ot relay 604, upper contact of cani 616, brush 622, conductor 625, upper contacts of cam 705, brush 7 53, ring side of the called line, to ground through the bell 714 of the desired subscribers station. Through the operation or" interrupters 647 and 643, the bell 314 is operated in accordance with a one-ring code. During the application ot ringing current, ringing relay 604 connects ground over its innermost upper lront contact, the lett contact ot cam 617, brush 621, conductor 624, lower contacts of cani 702, brush 752, and thence to the tip side ot the called line for shunting out the bells of the substations connected to the tip side of the line.

lininediately following the initiation ot the ringing operation and the deenergization ot relay 353, relay 602 deenergizes, releasing relay 601, which again connectsy the windings of coil 600 across the tip and ring conductors 501 and 502 o't the trunlt er:-

tending back to the district operator. Relay 359 is again. energized, closing a circuit Jfor relay 323 which ina-y be traced troni battery through the winding ot relay 323, the upper contacts of cain 321, the right contact ot relay 302, the innermost lower contact of relay 353, the contact oit relay 359, the inner right contact ot' relay 362, to ground at the right contact ot cani 316. Relay 323 energizes in this circuit and closes a circuit for advancing sequence switch 310 into the talking position 15. This circuit extends from battery through the winding ,of seicc i lao

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