US1449511A - Telephone system - Google Patents

Description

. IDE

5 sheets-sheet l f Y .ini/F2727?? Harry/ZEE'.

Mar. 27, 1923.

' H. IDE

TELEPHONE SYSTEM Filed Feb 14 1919 5 sheets-sheet'J 2V Kw www LBR MNMUNE .E

ot a call from substation A., to automatically connect with an idle lirst selector C as shown in Fig. l, part l. The subscriber at A, by theuse of the calling device in connection with his substation equipment, may by its actuation, operate the iirst selector C to extend the connection Jfrom the said substation A to an idle connector, switch D. The subscriber at A then, may by further actuation of his calling device, operate the connector switch D kto connect with the terminals of the called-tor line E. It the called line is idle, ringing current is automatically applied to the terminals thereoi' `to signal the called-for subscriber. Should the line of the called for subscriber be` busy, a characteristic busy signal will .be automatically transmitted back to the calling subscriber who `-may by replacing his receiver upon its switch hook release the switches which were used in extending his line to the line ot the :called- 'for subscriber.

The switch B, as dia-grammatically illustrated, comprises a double-wound line and test relay LR, a single-wound*,cut-off relay CO, and a motor magnet MM. The line relay LR is adapted to be energized 4over the two sides of the subscribers line in series, the cut-olf relay CO is adapted when energized to disconnect the subscribers line circuit from the line relay LR., and to connect the switch wipers to the subscribers line circuit, providedthe line switch B is bein?? used for calling purposes. The motor magnet Mil/l is provided for stepping the switch sliatt and wipers 2, 3 and el step by step over the bank contacts 5, 6 and 7. The switch wipers 2, 3 and el are adapted to always be rotated in the same direction and do not restore to normal, that is, the switch wipers do' not have a normal position, but remain in their antecedent progressive position when a connec" tion is released. The wipers 2, B and Il are double-ended wipers and as one contacting end of these wipers moves oit the last contacts ot their respective switch banks, the other contacting ends thereof move onto the first contacts of the switch banks. The otl'- normal .contacts ON are so arranged that when the line relay LR is energized, they are moved to their oil-normal position and are returned to their normal position by the energization of the cut-ott relay GO, that is, these off-normal springs are so arranged that when the line relay LR is energized a catch mechanism is koperated to release the off-normal springs to their operated position, and upon the energization oil" the cut-oft relay C() the springs are returned to their normal positionin whichposition the catch mechanism again 1s brought into operation to hold the' oifnormal springs in their normal position.

The .switch shaft which carries wipers 2, 3 and 1- 1s providedvwith a ratchet mechanism which is adapted to cooperate with the driving pawl controlled by the motor magnet lVllll to rotate the switch shaft and wipers in a clockwise direction.

A further mechanical arrangement is provided for the line switch and connects the line relay LR and the cut-oil:1 relay CO in such a manner that the armature of the cutotl' relay CO can not befully attracted unless the line relay LR has ,been energized lirst, that is, ir" the line relay LR has been energized the armatureof the cut-ott relay CO may then be energized to move its switch contacts to their alternate positions into engagement with their alternate contacts, while it' the cut-ofi' relay CO is energized before the line relay LR' is operated, the armature oi the cut-ot relay is permitted to move only a sulicient distance that its contacts 9, 1() and 11 are moved from engagement .with their back contacts 12, 18 and 14, respectively, but not into engagement with their front contacts 15, 16 and 17. This feature is provided so that when the substation A is called from a connector switch and the cut-ori relay CO energized, the subscribers line can be disconnected from the line relay LR ot' the switch B, but cannot be connected with the switch wipers of the switch.

Referring now particularly to Figs. 2 to 7, inclusive, l illustrate the cut-ott relay CO and its associated mechanism in its various operative positions, and in Fig. 2 illustrate the cut-ott' relay CO in itsnormal position, in which its armature 106 is in its retracted position and its associated contacts L in their normal position, and in Fig. 3 I show the off-normal contacts ON in their normal position andmounted on the extension 10412 of 'the heel iron 10a of thecut-otf relay CO, and the movement ot the off-normal contacts 0N is jointly controlled by the line relay LR and the cut-orf relay C0. An armature shaped member 116 vis pivotally supported at the 'forwardend oi the extension 10112 byv means ot a suitable pivot pin, which pin also pivotally supports the armature 106 of the cut-off relay CO. A. bracket 1 24Lsuitably secured to the mounting plate, pivotally supports a latch 126, and the leg 128 of the member 116 is provided with a shoulder 129, which rests in a notch 130 in the latch 126. The edge 131. of the said `shoulder 129 engages the side132 ot the notch 130', retaining the member 116 in its position as illustrated in Fig. to hold the voil-normal cont-acts ON in their normal position.

' iln arm 141" secured to the armature 106 ot the relay CO is operatively associated with a latch 143", which latch 141-3 is also pivotally supported by the bracket 1241 and is also operatively associated with the leg 128 ofthe member 116', the saidlatch 143 lying adi acent to and parallel with the latch 126. The latch 1113 is provided with a When :a cali. is initiated the line relay'LR is energized and its armature is attracted, and the angular arm 145 secured tothearmature ot' the relay LR is moved in an upward direction and engages the extension 1262 of the latch 126. lthis causes the latch Y Y I l Number 175,364, iledilunelS, 1917. lt'is to be understood, however, that the circuits- 126 to be raised, and when the face `132 of the notch 130 passes beyond the edge 131 i oi' the shoulder 129 ot' the member 116', it releases the said member 116, allowing` it to rotate about its pivot and permitting the oitnormal contacts DN to assume theirl alter` nate position, as illustrated in Fig. 5. When 126 rests uponthe edge 147 ofthe shoulder The latch 1 3fis also raised dueto the extension 1262 passing under the latch 143 so that when the latch 143 is inthis position, as illustrated in Fig. 4, the arm 141 is clear of the notch 144 in the forward yend of the latch'143. The positions of the latches 126 and 143 when in their off-normal position are illustrated in Figs. 4 and and the shifted oil-normal contacts C@ in Fig. 5. After selection thecut-oii relay CO cnerq'izcs to attract its armature 106, ifollowed yby the de-energization ot the line relay LR, andthe attracted armature 106 carries the arm 141 with it and in its movement engages the member 116 and again rocks itabout its pivot. The line relay LR- upon restoring allows the arm' 145 to disengage fthe extension 1262 of the `latch 126 and the the edge 132 of the notch 130, the off-normal contacts ON are locked in their normal position yuntil another engagement of the line relay lill. The cut-oil` relav C@ energizing' shiits the springs li to their alternate positions and thc latch 1.43 `is in such 'a position that its bottom edge 146 rests on the upper edge 149 of thearm 141', as clearly illustrated in Fig. 6. "Upon the restoration citent-ofi' relay C0, its armature retracts, the arm 141 moving therewith so that when its edge 150 passes the edge 151 1 of the notch 144 of the latch 143., the said latch 143 rocks on its pivot and again allows `the arm 141 to rest in the notch 144 o'fthe y latch 143.

`New, should the line associated with the cut-off relav CO be a called line, the said cutoii relay C@ will'be'energized, butdue to the arm 141 resting in the notch 144 of the `latch 143 ig. 2), the movement ot the armature 106 is limited by the amount of play that the arm 141 has in the notch 144.

rlhe circuits shown for the selector switch C and connector switch D are adapted to worlr with a switchstructure similar to that shown in my cai-pending` application, Serial may be used in connection with various switch structures o1' the art.

The iirstselector -C lcomprises ran impulse relay 1R, which relay is energized and dep energized by impulses from the calling dein this position the edge 146ioi the latch' vice CD at the calling substation A, and the energization and de-energization of the relay llt brings about the actuation of the `primary magnet PM to step the iirst selector switch wipers 209, 210 and 211 in a primary direction to .a certain O'roup ot contacts. A secondary magnet Sli is provided for said selector which automatically steps the wipers 209, l 210 and 211 in a secondary direction over the contacts 220, 221v and 222 in the selected` groupy to seek an idle set of contacts leading,- to a connector, as D. A switching relay 'll is also provided which, when enerf gized, extends the connection or" the 'calling substation A tothe idle connector D. Primary and secondary oil-normal contacts PGN and SON, respectively, are provided.

llhe said primary oi-normal'contacts PON assu-me their alternateposition onthe iirst `step of thewipers in a primary direction,

and the secondaryof-normal contactsSON assume their alternate position upon the iirst ste-p ot the wpersin a secondary direction.

vThe connectorswitch D is provided with an impulse relay IR, responsive to the impulses ot' the calling device CD at the calling substation A, which relay 1R brings` about the actuation of the primary magnet PM to step the connector switchy wipers 235, 236 and 237 `in a primary direction` to a certain group of lcontacts containing' contacts of the` called line E. A switching'relay S117 is pro-` vided which energizes upon the termination of the first set of impulses to connect the secondary magnet SM in circuitwith the impulse yrelay IR", to be actuated bythe cn- `ergization and the de-energizzationy thereof to step the connector switch wipers 235, 236, and-237 over the contacts 250.v and 252 in `the selected group to seek the contacts of the called line. y

, A test relay TR is also provided which is actuated to test the busy or idle condition of the called subscribers line'. Thesaid test relay TR operates to connect the busy back apparatus .lto the calling subscribers line 'to notify `the calling subscriber of the busy `condition of the called line.v A ring' controlA scribers li-ne from the ringing current, generator Gf.; A back bridge orsupervisory relay SH is also provided which operates upon the response oi the called subscriber and controls disconnection orv prevention ot further applications of ringing current to the called subscribei"s line. Primary and secondary ott-normal contacts PGNA and SON are provided to :.issnineftheir alternate positions, respectively, Vupon the movements ot wipers 235, 236 and 237. y

To the right of Sheet substation E similar to substation A, the said substation E being connected to a line switch Having described in general tiie structure i of the switches and apparatus, lr will now.

at the exchange similar to line switch B.

explain more in detail the operation ot' the same.

Assuming that a call is to be traced from the calling substation A to the called sul station lil, upon the removal ot' the receiver by the subscriber at the calling substation A,

I line rela f LR of switch l is energized b current traced from battery,through the upper winding oct relay Llt, contact 100 ot motor magnet MM, normal contact 101 ot' olinormal springs ON, contacts 111 and 11 of relay CQ, through the calling substation baclr potential.

through contacts 9, oi" relay C() and through the lower winding of relay 11R to ground. Line relay LR upon energizing` trips the ott-normal contacts ON to their operated position. ris before mentioned,

wipers` Band @always rest upon the set ot contacts 5, G and 7 last used, and assuming the contacts upon which the wipers now vrest are busy, due to another subscribers line switch having selected the first selector last used by the subscriber E1, the engaged pri.- if'ate contact will be found -toV contain a busy rl`he tripping ot off-normal contacts ON connects the upper winding ot line relay LR tothe private bank contact 5,

which we have assumed contains abusy potential.` over a circuit extending from batteiy, through the upper winding of relay LR, normal contact 100 of motor magnet MM, alternate cont-act 101 of olf-normal springs ON, contacts 13 and 10 of relay CO, to private wiper 2 and the grounde-d'pbanlr Contact The line relay will thus remain' energized until its circuit is opened at contact 100 ot the motor magnet MM. The closure of Contact 102 of relay LB closes a cir' Vmagnet lilM and permittingr the said motor magnet MM to restore. Should the contacts now engaged by the wipers be busy, relay LR energizes by current through normal contact 100 ot' motor magnet MM and again closes contaet102, energizing motor magnet MM, before` described. Theline and test relay LR' and magnet MM are thus alteri nately energized anddefenergized, magnet 2,1 show a called MM stepping wipers `2, 3 and 4 from one set .of contacts to the next as long as busy, that is, as long as grounded contacts are encountered, and relay LR energizing each time a grounded bank contact is encountered. yMagnet MM alternately opens and Acloses its contact 103, andithus a vibratory circuit is closed through the winding ot vcut-off relay C@ to ground, through contacts /1 ot'yoff-normal contacts ON. The winding of relay C@ is of high resistance and as motor magnet MM e-nergizes and deenergizes with great rapidity, the said winding ot relay C@ does lnot effectively energize and attract its armature while the mo-r tor magnet MM is operating. The relay CO may. also contain a copper sleeve to maire it slightly slow to energize. Closure of contacts 10401 orf-normal contacts ON places 9 battery, through the winding of relay CO, y contact 103 or' motor magnet MM, and contact 10% of off-normal contacts ON to ground. Relay CO upon energizing restores the oil-normal contacts ONto their normal positions, connects the subscribers line to linewipers 3 and 4 and connects the said winding of relay C@ tofprivate wiper 2. The relay CO lbeing slow 'to release is held .up momentarily until a substitute circuit is established for therelay CO, ras will be presently described.

' The connection ot' the subscribers line to line wipers 3 and 4l ot the switch B closes an energizing circuit for impulse relay 1R Aot the'idlefirst selector C over a circuit 194 and through relay R to ground.

Closed alternate contact 195 otrelay IR energizes relay 196 by current from' battery, through the upper winding of relay 196, contact 195, to ground at normal contact 199 ol' the primary oll--normalcontacts PON. Relay 200 is now energized, from battery through the upper 4\ \f'iiniling ot said relay 200, alternate contact 19(5to grouiul at norH mal rentar-t 199. The closingot alternatey contact 201. of relay200 establishes a substitute energizing circuit itor'relay C() ot the line switch (l beto t `has had time to (lc-energize, said circuit being` traced 'from battery through relay CO, normal contact 1023, Wiper 2, contact 5, conductor 203, alternate Contact 2041, to ground at alternate contact 201. `Relay C() remains energized until time o1 release. The connector contacts 1.07 e111 are also made `busy by the grouinl just traced.

It" the private contact engaged by the wiper 2 idle when the subscriber A initiatesa call, the line relay LR is energized as before described, and contacts ON assume their alternate position, but the closing ot contact 102 ofrelay LR does not energize magnet MM since there is no ground on Contact@ and the magnet Mil/l remains inert. rlhe cut-oil relay UO is iinniediately energized Ito ground atfcontact 1,01-, restores contacte UN as bel'iore described, and the relay C@ is held energized over lthe circuit to ground att), as already described. 'lhus switch l only travels when its wipers are in engagement with a busy trunk when a call is initiated.

11n idle first selector C having been seized as just described, and assuming that the number oit the called substation E is 3115, the subscriber It actuates the calling device CD to send three impulses ot current over the line, which impulses bring about three rapid ile-energizations and energizations or` the impulse relay 1R. The primary magnetPll/l is energized and cle-energized three times, due to the closing and opening of normal contact 195 olf relay IR (circuit being traced Via 20G, 20T, 195, 208) which magnet operates to step the wipers 209, 210 and 211 oit the first selector C in a downward primary direction to the third group oi? contacts, thus selecting the three-hundreds group ot connectors. Alter the last impulse, the relay 200 de-energizes, due to a circuit being closed through the lower Windingl of the said relay 200, normal contact 212, alternate contact 21?` of relay iR, and alternate contacts 2111 and 199. The said primary oit-normal contacts PON moveto their alternate'positions upon therst step of the Wipers ot the first selector D, and the energizing circuit tor the lower Winding of relay 200 just mentioned is closed upon the iirst step o1? the wipers oit normal, but the relay 200 does not de-energize during the sending oit impulses, it being differentially wound and only re neutralizing winding during, the iin se operation o'l relay llt. As soon ceivino` short impulses ojl current through its aboyejmentioned circuit through the lower winding of relay 200 is steadily closed, the

` lower or neutralizing Winding builds up and are transmitted through its lower or neutralizing Winding ydue tothe construction and adjustment o1 the said relay 196. Upon the de--energization of the relay 200, an energizing circuit ior the relay 215 is established from battery, through normal contact 216 of relay T, normal Contact 217, normalcontact 218 of' the secondary olli-normal contact SUN, normal Contact 201, alternate contact 204i to `ground at 199, and relay 215 energizes secondary magnetvSM by current from battery through said magnet SM to ground at contact 219. Secondary magnet SM steps the Wipers 209, 210and 211 one step in a ro# tarf or secondary direction` to engage the lirst set of contacts 220, 221 and 222 and the opening of normal contact ,217 at magnet Sli/l cle-energizes relay 215. Contact 212 opens the circuit of the lower Winding of relay 200 which energizes again. Relay 215 opens Contact 219, cle-energizing secondary magnet SM. Upon the v irst step of the Wipers 209, 210 and 211, the secondary offnormal contacts SON assume their alternate position, opening the initial energizing circuit oi' the relay 215, and should the private iyiper 209 of `the, first selector D engager a contact leading to a busy connector, a substitute ycircuit is established for relay 215 traced from battery through the Winding of the relay 215, normal contact 216, normal contact 217, alternate contact 223, alternate contact 2211 and Wiper 209 to the grounded busy Contact 220. The resulting closing of contact 219 again energizes secondary magnet SM. The relay 215 and magnet SM are thus alternately energized and cle-energized to step the Wipers 209, 210 and 211 in aiseeondary rotary direction to seelr the contacts olf an idle connector switch as E. lVhen a contact 220 leading to an idle connector is encounteredby the Wiper 209, an energizing circuit of the relay 215 is not again closed, and no further energizations of the secondary magnet SM occur. By this see-saw action of relay 215 and magnet SM av positive driving operation of the secondary magnet SM is securedand the selector C Willnot stop on a busy contact or go past an idle con-r tact because unless relay 215 is energized, mami-et cannot be energized, and relay 2153 can only be energized when magnet SM Ais at normal and' `private wiper 209 'is restingon a busy contact. The relayy 200 does not cle-energize during the secondary movement ot the wipers, due to its adjustment and the rapidity of the interruptions of contact 212 of 'secondary magnet SM. The steady closure ot Contact. 212 of magnet SM after its last Cle-energization closes a circuit for the lower winding of the relay 200, as previously described, and due' to' its differentialv construction, it cle-energizes, whereon van energizing circuit for. the relay T is established traced from battery through the winding ofthe said relay T, alternate rcontact 218 of' the secondary olif-normal contacts SON, normall contact 201, contact 204 to groundat 199.` The opening otnormal contacts 192 and 193 of relay T opens the energizing circuit of the impulse relay 1R, and the closing of normal contact 195 of said relay 1R' closes a circuit through the lower winding ofthe relay 196 traced trom battery, through the said lower winding, normal contact 195, to ground at contact 208 of relay 196', which relay 196, due to its vdifferential winding, neutralizes and restores to normal, and 196' opens the circuit' of relay 200 permitting' the latter to restore. The closing o1" alternate contacts 192 and 193 ot relay T extends the connection of the calling subscriber A to the idle connector D, engagedby wipers209, 210 and 211 of the first selector'C, bringing about the energization or' the impulse relay 1R' of connector D over a circuit traced from ground through one winding ofthe relay IB', contact 222, wiper 211, alternate contact 193, contacts 7-4, alternate cont-acts 17-11, through the substa- `tion A, alternate contacts 12-15, contacts 3&6, alternate `contact 192 wiper 210, contact 221,and throughthe lelt hand winding ofthe relay 11i/to battery and ground. The restoratio'not the relay 196 of the irst selector Copens the initial energizing circuitot relay Tat C, but the relay T being slow to release has a substitute circuit established or'it, traced from battery through the winding 'of said relay, its alternatey contact 225, wiper 209, bank contact 220, conductor 226, and conductor 227 to ground at alternate contact 228 o'l' the impulse relay 1R'. The said relay T remains energized until the termination of the conversation.

The energization of the relay 1R' energizes relays, 229 and 230, the circuit ot relay 229 extending from battery through the right hand winding of said. relay, normal Contact 231 ofthe primary off-normal contacts PON', conductor 226 and conductor 227 to groundat alterna-te contact 228 ot relay IR'. A circuit is also closed through the lower winding of relay 230 upon the energizat'ion of relayl'R extending from battery through the lower winding of the relay 230, conductors 231', 232 and alternate contact 233 to groundy at alternate contact 228 of' relay 1R'. However, the relay 230 does not opera-tively energize at thisr time owing to the fact that the energization of relay 229 closed a circuit through the upper winding of relay 230 and at the time relay 229 energized. The windings of relay 230 being wound diiferentially, prevents the relay operatively energizing. Relay 229 locks itself to groiuid at 234. Four impulses now transmitted from A de-energize and energize relay 1R tour times causing the primary magnet PM to energize and de-energize tour times to step the wipers 236 and 237 in a downward primary direction to the fourth group oft contacts containing those of the called line. Upon the first energization of relay I t', the circuit through the lower winding of relay 230 is opened, thereby permit-ting the same to immediately energize. kr1`he circuit of the primary magnet PM may be traced from battery through the winding of the said magnet BM', normal contact 238 of switching relay SW, conductor 239, alternate contact 240 ol relay 230, normal contact ot relay 1R', conductor 227, conductor 226, through normalI contact 231 or the primary oit-normal contacts PON to ground at alternate contact 234 of relay 229. After the primary off-normal contact 231 assumes its alternate position, which occurs upon the first step of the switch shaft, the ground ted from contact 241 of relay 242* is substituted. for the ground ted through contact of relay 229. After the last impulse of the series has been sent, the steady ilow of current through bothwindings of' relay 230 causes the said relay 230, due to its dili'erential action, to neutralize and restore its contacts to normal, but it does not restore during the sending of impulses due toits adj ustn'ient, construction and the rapidity ot the interruptions of contact The closing ci' normal Contact l243 or' relay 230 energizes switching relay SW' by current tlirough the winding of said relay SW, its malte-beforebreal; contact 244, normal contact of secondary oli-normal springs SUN', conductor 246, normal contact 243 of relay 230, and conductor 247 to ground at alternate contact 248 ot' lprimary oil-normal contacts PON', and relay SV locksitself to ground via contacts 257r and 248. rhe closing ot alternate contact 23801 the'switching relay i 51W merely substitutes secondary magnet SM" for magnet PM', so that when the calling subscriber at the substation A sends the last set oi' impulses,which we have assumed are livev in number, relay 1R' energizes magnet SM five times, and secondary magnet SM' steps the wipers 235, 236 and 237 in a secondary rotary direction to engage contacts 250. v 251 and 252 of the called line. Upon the iirst impulse of the last set,- the relli lay 280 again energizes to permit thev secondary magnet SM to be operated, and atter the lastv impulse the relay 230 is again deene1.gized, as previously described, and. close-3 a circuit for the test relay TR traced trom battery, through the Wind-ing ot the said relay, conductor 25B, the alternate contact 254, alternate contact 245, ot the secondary oit-normal contacts SON, (said contacts haring been moved to their alternate position upon the lirst step of the wipers in their secondary direction), conductor 246, normal contact 243, conductor 24:7 to ground at 24:8. The closing ot alternate contact 255 oli relay TR connects the said relay over conductor 256 to the test or private wiper L85, and should the called line be busy the private contact 2:10 of the called line would be grounded, thus closinga locking circuit 'tor the said relay TR through the private Wiper.

CaZZecZ Zinc idle.

Assuming that the called line is idle, private contact 250 ol the called line will he tree of ground, and the relay TR will not remain energized but will fle-energize. The ,opening ot normal contact 257 of relay TR'upon its momentary energization opens the circuit ot the switching relay SW ,and the relay SW (le-energizing` opens the circuit tor relay TR at its contact 254, leaving the relayTR de pendent upon the potential found upon the private contact 250 of the called line. Since,`

262. The closing of alternate contact 263 oit.

relay 242 short circuits the lower Winding ot' the said relay, and the closing ot its alternate contact 264 closes a circuit through the upper Winding of the said relay through the alter nate contact 26a and conductor 261 to ground at 262. The relay C0 of the line switch B associated with the called line E attracts its armature but its movement is limited, as previously described, but this movement allows contacts 177 and 178 to assume positions to remove the substation control ot the line switch B of the called line E. The other contacts oft the relay CO are not at'- iected due to this limited movement." f i The closing ot alternate contact 265 o't relay 242 connects the interruptor I of the relay 266. circuit tor relay 266 being traced trom battery through relay 266, conductor 267, alternate contact 265, conductor 268,

normal contact 269 "and through l to ground.` The relay 266 is thus intermittently energized and de-energized, and uponeach (le-energization` ringing generator is connected to the called line over a circuit extending from the ungrounded pole ot' the generator Gr,

relay 266 is energized, a circuit for the relay SR is closed, from battery through the lower winding oit the relay SR, through alternate contact 27a of relay 266, Wiper 287, contact 252, throughthe now closed upper `contacts of the substation lswitch hook at the called substation E, back through contact 251, Wiper 236, alternate Contact 275 of relay 266, and through the lupper Winding of the relay SR togroun'd.y The relay SR, upon energizing closes an energizing circuit tor the ring ing control relay RC, Which maybe traced from battery (through the Winding of the said relayPtC, its makebefore-break contact 277, to ground at 278. Contact 279 loclfs relay RC from battery, through the Winding ofthe said relay RC, its alternatecontact 279 Iand conductor 247, to ground at alternate `contact 248 ot the primary olf-normal contacts PON. The openingof normal contacts 269 and 270 disconnects the interrupter I and the ringing generator Gf to prevent further application of ringing current. A substitute circuit tory the relayy 266 is now established which may be traced from battery, through the Winding ot the relay/266, conductor 267 alternate contact 265,`conductor 268, alternate contact- 269 and conductor 424C? to ground at 24:81 The subscribers are now in conver-` sational circuit, and thetalking circuit may be traced over the heavily marked conductors, said conductors having the condensers 1 l and K2 interposed.

Release.

tact 216 of relay T energizes relay 215 by current Ytrom battery, through said relay 215,

normal contact 216,; normal contact 217, normal contact 223 and contact 21e, to ground at 199. The closing et' alternate contact 219 ot relay 215 energicces secondary magnet SM, and the relay 215 and secondary magnetSM switch B. The restoration of the cut-oil re- Cil i to normal.

lay C() restores the individual switch lV to normal.

The subscriber ll restoring his receiver upon its switchhool interrupts the circuit ot the relay JR at the switch hook contacts, causing thesaid relay to de-energize. The closing of normal contact 285 of relay SR closes a circuit through the left hand winding ,of the relay 229 which `may be traced Ifrombattery, throughthe leiit hand winding cthe said relay 229, alternate contact 286, conductor 287, normal contact 285 and conductor 288 to ground at normal contact 228. Due to the dirferential construction of relay 229, the saidrelay' neutralizes and restores The closing of normal contact 289 of relay 229 closes an energizingcircuit for the secondary magnet SM', from battery, through said magnet, conductor 290, normal contact 289, contact 291, through the interrupter I to ground. The secondary mag net SM thusk'steps the wipers235, 236 and 237 beyond the last setl of contacts in the group, the wipers'then restoring to normal from this position'loy spring tension. The restoration of the relay 229 opens the circuit ofl relay 242 at contact 262, and the relay restoring opens the circuit of relay 266 at contact 265. ril`he primary olf-normal contacts PON having restored'upon the restoration o'-the switch, the opening ot the contact 248 cle-energizes relay RC. The relay also brings about the Vcle-energization ot' the4 cut-oli relay CO of the line circuit E which is associated with the called subscriber E.

All `the apparatusV used in establishing a connection between a calling subscriber at the substation A and-the called subscriber at the substation Ev is now at normal and available for use in establishing other connections. v

Assuming now 'that the subscriber at the called substation E was first to replace his receiver upon the switch hook, the opening of the switch hook contacts atvthe substation E brings aboutv the cle-energization of the relay SR. Nothing else happens at this time as the relay IRl is still maintained energized over the line of the calling' substation A. The calling subscriber at' the substation A replacing his receiver interrupts the circuit of the impulse relay IR at the switch hook contacts. The relay IR deenergizing closes a circuit 'l'or the lett hand winding of relay 229, causingthe said relay to cle-energize, as hereinbetore described. rlhe restoration of the individual switch B, first selector C and connector D is the same as previously described from this point on. Should the called subscriber E tail to replace his receiver upon the switch hook after the conif'ersation is terminated, the replaccontinued energization of the relay SR, thus holding the contact 285 of said relay in its alternate position preventing the differential wound relay 229 from restoring to normal, and closingthe energizing circuit for the secondary magnet Sil/l. The relay 2230 energizes when the line relay IR drops back but is immediately restored to normal, due to the closure oi' an energizing circuit through the lower winding of the said relay 230, which may be traced from battery, through the said lower winding, conductor 232, alternate` Contact 285, conductor 288 to ground at alternate contact 228 of the now restored impulse relay IR. Relay 230 being difierentially wound, restores to normal and the closing or normal contact 295 ot the said relay 23() places a ground upon the private contact of the connector D over a circuit which mayy be traced from ground at contact 248, conductor 247, normal contact 243 of relay 280, conductor 246, alternate contact 245, normal contact 295, alternate contact 296 ot' the secondary off-normal contacts SON', to the private'contact 220. The placing of this busy Vpotential upon lthe private contact prevents any tirst selector switch C Afrom selecting thecontacts of this busy connector.

Called rZine busy.

Assumingnow that the called line is busy, the operationoi' the circuit is the same up to and including the time that the relay TR momentarily energizes, The line being busy, the private contact 250 has a ground connected to it, and it thus closes a locking circuit for the test relay TR 'rom battery, through the winding of the said relay,` its alternate Contact 255, conductor 256, and the wiper 235 to the grounded contact`250. Alternate contact 297 of the test relay TR remains closed and connects the busy signal BB tothe calling line to transit signal to A,

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thus notifying the subscriber of the busy condition of the called substation E, Relay RC is also energized when connection is made to a busy line to prevent an application of ringing current from being applied to the called line if the called line should become idle before the connector D is disconnected from the bank contacts of a called` subscribers line.` The relay RC upon energizing locks up through its own make-before-break contacts 277 and 279 to ground at alternate contact 248. rlhe calling subscribe er now replaces his receiver, bringing about the de-energization of the impulse relay 1R', and the relay Hl restoring, opens the circuit of the relay T ofthe first selector C, which, as previously described, bringsy about the release of the iirst selector C and theindividual switch B. The relay 1R cle-energizing, restores relay 229, (since `the relay Sil has not been energized) and by the closing of circuit through. the left hand winding of said relay 229, the closing `of contact 289 now connects secondary magnet SM and iuterrupter l, and the connector restores to normal by spring tension. .lhe primary oit-normal contacts PON and ,secondary off-normal contacts SON are also restored,`and all the apparatus used is now at normal and available for use in establishing,

other connections.

While 1 have shown a system of 1,000 capacity, it is to be understood that by inserting second selectors, the system may be increased to a 10,000 system, etc.

From the foregoing it is at once apparent that I have so arranged the combined line and test relay of my individual switch that the said relay will operate very eiciently when energized over a subscribers line circuit, due to the fact that the two windings of this relay are connected in series when so actuated and the windings are of the right resistance to operate most efficiently, and when the relay is used for testing purposes only its one winding is connected in circuit, which winding is of the right resistance to permit a very eiiicient operation of this relay under these conditions, thereby permitting the motor magnet of the switch to operate at a very high rate of speed.

While l have described my invention operating in connection with a well known system, 1 do not wish to be limited to this eX- act disclosure as my invention may be applied to other systems without departing from the spirit of' the invention, and l, therefore, do not wish to be limited to this exact disclosure but aim to cover all such changes and modifications as come within the spirit and scope of the appended claims.

What 1 claim as new and desire to secure by United States Letters Patent is:`

1. A telephone system including an auto matic switch, a motor magnet for said switch, a double wound line relay for controlling said motor magnet, an initial energizing circuit for said line relay including the two windings thereof in series, a second circuit for said relay including one winding thereof and a contact ofsaid motor magnet, and a circuit for said motor magnet including a contact of said line relay.

2.1@ 'telephone system including an automatic switch provided with a contact maker, motor mechanism for controlling said contact maker, a double wound relay, an initial energizing circuit for said relay including the two windings thereof in series, a second circuit for said relay including one winding thereof and a contact controlled by said motor mechanism, and a circuit for said motor mechanism including a contact controlled by said relay. i

3, A telephone system including an auto matic non-restoring trunking switch, a motor magnet for said switch, a combined test and line relay for controlling said motor magnet, a cut oiflrelay for said switch, an initial energizing circuit for said first relay including contacts controlled by said cut oil' relay, and a second circuit for said test relay including a contact of said motor magnet and a second contact of said cutoff relay.

l. A telephone system including a `nonnumerical lnon-restoring switch,Av a `double wound test relay and a driving magnet for said switch, a circuit for said test relay including the two windings thereof and a contact of said driving magnet, and a circuit for said driving magnet including a contact of said test relay.

5. A telephone system including a nonrestoring automatic switch provided with a contact maker, a motor magnet for actuating said contact maker, a double wound test relay fer said switch, an initial energizing circuit :for said test relay including the two windings thereol in series, a second circuit forsaid test relay including only one winding thereof and a contact of said motor magnet, and a circuitfor said motor magnet including a Contact of said relay and said contact maker.

6. A telephone system including a nonrestoring automatic switch, a double wound relay, a motor magnet, and a cut off relay for said switch, an initial energizing circuit for said double wound relay includingthe two windings thereof in series, a second circuit 4for said double wound relay including a contact of said motor magnet and a contact of said cut oif relay, a circuit for said moto-r magnet including a contact of said double wound relay, and a circuit for said cut o relay including a contact of said double wound relay.

` 7. A telephone system including an automatic switch, a motor device for said switch,

test Contact, a double wound relay for controlling the said motor device, an energizing circuit for said double wound relay includ ing the two windings in series, a second circuit for said relay including one Winding thereof and an armature contact controlled by said 4motor device and said test Contact, and a circuit for said motor device including a contact controlled by'said double wound relay and said test Contact.

8. telephone system including a subscribers telephone line, a. trunlring switch for said line, trunk lines extending from said switch, active contacts for said switch always in engagement with some one of said trunk lines, Whicl'i trunk line is the one last employed by said switch for extending a connection therefrom, a double wound relay for said switch, a motor device for actuating said active contacts, Ineans for closing a parallel circuit for said relay and said motor device whereby if one or said active contacts is in engagement with a busy passive contact said motor magnet will be operated to advance said active contacts, While if said active Contact is in engagement with an idle passive contact said relay is cle-energized to cause said subscrihers line to be connected with the engaged trunk line.

9. A telephone system including a sub scribers line, aswitch individual thereto, a double-wound relay for Said switch, a motor magnet for said switch, an energizing circuit for said doublewound relay including the two windings thereof, a second test circuit for said double-wound relay including only one winding thereof and a contact of said motor magnet, and a circuit for said motor magnet including` a Contact of the said double-wound relay.

10. A telephone system including a nonnumerical trunk switch, a double-Wound line relay therefor, a motor magnet therefor, a circuit including the two windings of said line relay in series, a second circuit for said relay including one winding of the same and a. Contact of said motor magnet, and a circuit for said motor magnet including a contact of said relay.

l1. A telephone system including a nonnumerical non-restoring trunk switch, a

, double-wound relay and a motor magnet for said trunk switch, a circuit for said relay including the two windings thereof in series, a second circuit for .said relay including one win-ding of the same and a switch Contact of said motor magnet, and a circuit for said motor magnet including a Contact controlled by said relay.

Signed by Ine at Chicago in the county of Cook and State of Illinois, this 12th day of February, 1919.

HARRY H. IDE.

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