US1386728A - Machine-switching telephone system - Google Patents

Description

L. POLINKOWSKY.

MACHINE SWITCHING TELEPHONE SYSTEM.

APPLICATION FILED AUG-27,1918.

1 ,386,728 a Patented Aug. 9, 19211..

7SHEETSSHEET L. POLINKOWSKY.

MACHINE SWITCHINGVTELEPHONE SYSTEM.

APPLICATION FILED Aue.27, 191s.

1,3863%. Patented Aug. 9,1921.

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L. POLINKOWSKY.

MACHtNE SWITCHING TELEPHONE SYSTEM.

APPLICATION FILED AUG-27. 1918.

1,386,728, Patented Aug. 9, 1921.

TSHEETS-SHEET 3- L/pa P/firko wsky.

L. POLINKOWSKY.

MACHINE SWITCHING TELEPHONE SYSTEM.

APPLICATION FILED AUG.2J, 191.8.

3 32 Patented Aug. 9, 19211.

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Patented Aug. 9, 192K,

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MACHINE swncmm; TELEPHONE SYSTEM.

APPUCATION FILED AUG.27, I918- fly A1931.

L. POLINKOWSKY. MACHINE SWITCHING TELEPHONE SYSTEM. APPLICATION FILED Aug-2 7, 191-8.

1,386,7 2, Patented Aug. 9,1921.

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entrant LIPA POLINKOWSKY, OF LONDON, ENGLAND, ASSXGNOR TO'XVESTERN ELECTRIC COMPANY, INCORPORATED, OF NEE YCBK, N. Y., A COEEORATION OF NEW YORK.

MACHHE-SWITGI-IING TELEPHONE SYSTEM.

Application filed. August 27, 1918.

To all whom it may concern:

Be it known that I, LIPA PoiiiNKowsKY, a citizen of Russia, residing at London, England, have invented certain new and useful improvements in hlachine-Switching Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to machine switching telephone systems, and more particularly to telephone systems in which connections are extended from a manual A board over a semi-automatic B board to the automatic switches of a distant automatic eX- change or automatic satellite.

A feature of the invention is the provision of a semi-automatic operators position provided with a single key set and two or more sets of registers controlled thereby, each set of registers comprising only a plurality of relays.

Another feature of the invention and one relating to the above is the provision of register sets, a plurality of which are controlled by a single set of number keys, each register set comprising a set of number relays, a set of counting relays for the impulses, a set of counting relays for the series of impulses, and means for operating one of the register sets only when the number keys are depressed.

Still another feature of the invention and one relating to the last named feature is the provision of a set of relays for connecting a trunk line to one only of the register sets upon the depression of an assignment key.

A further feature of this invention is an arrangement which enables the establishment of a talking-through connection over the contacts of the deenergized relays which serve for connecting the registerset to the trunk, together with means to establish this circuit only after the relays have been first energized and deenergized.

Another feature of the invention is a circuit arrangement in which the trunks extended over the B-operators position, are provided with sets of relays, one set operating upon the insertion of the plug at the A operators position for closing the fundamental circuit and the other set operating 0n the depression of an assignment key for temporarily connecting the trunk with a register set, the relay set responding to the ins tion of the plug on the A board being cited from fulfilling its function unless Specification of Letters Patent.

Patented Au. 9, 1921.

Serial No. 251,605.

the set of relays which establish the temporary connection with a register set have been energized, the sets of relays being so arranged in the circuit that the last named set of relays is utilized to establish overtheir contacts both a temporary connection with the register set and the through-talking consertion of the plug on the A board for clos' ing the fundamental circuit, and which insures that the closing of the fundamental circuit is delayed until after the plug at the A board has been fully inserted,

A further feature of the invention is the provision of means associated with the relay register sets for translating the numbers as set up thereon by the number keys into the system of notation used in the selecting switches of the machine switching system.

A particular feature of the invention and one relating to the last named feature is the provision of an improved counting relay circuit containing less than the usual nun ber of relays and an arrangement of circuits and apparatus connected therewith for use in connection with the translation scheme of the system whereby the counting relay circuit may send an additional set of impulses on a given units selection.

A still further feature of the invention is the provision of means for connecting a trunk line with one only of the relay register sets, preference being given 'to a'predetermined one of such relay register sets when both are free and the provision of means operating when both such relay register sets are taken for use to insure the complete operation of the last set taken for use whether the preferred set is maintained in use or set free.

A. further feature of the invention is the provision of a relay register set including a set of counting relays for the impulses, a set of counting relays for the series of impulses and a set of slow operating relays brought into operation at the end of each series of impulses and controlling the length of time the fundamental circuit is kept open on the register set.

A particular feature of the invention and operating relays into slow energizing and slow deenergizing relays, in such a manner that-their timely operation is made practically independent ofvariations in the'voltage of the, energizing circuit.

Figure 1 shows a cord circuit at an A operators position in a manual oflice of the well-known type. Fig. 1 shows a trunk line in an automatic satellite or exchange incomin from the A operators position.

Figs. 2, 3 and 3 show the keyboard, two register sets and. a counting relay set at a switchless. semi automatic B operators position to,which the trunk line is connected.

Inv Fig. 4 is shown a group selector on. the

incoming end of the trunk line in an automatic satellite, locatcd in the area of a man'- ual telephone system, and in Fig. 4 is shown a a final selector.

The same arrangement "is used: in an automatic exchange to establish connections from a manual board, in. which case the trunk lines can be divided into.

groups to be selected by the B. operator,

and the group selector shown to the left of this figure then represents the last group selector in the exchange. 1

The system disclosed as embodying the present invention will; be best understood from a description of the operation thereof. When a connection extended. to the manual A board is to be further extended to' an automatic satellite, the A operator cornmunicates Wlth the semi-automatic B operator, 1n the well known manner, over an order wire, giving her the name of the satellite and the number wanted. The B operator gives the A operator the number of the selected free trunk to the satellite in question and depresses the assignment key 201, indicated in Fig- 1 individual to this 1 trunk, which as a result is brought into connection with one of the free-register sets of the B position, shown in Figs. 2 and 3, each B position being provided with a set of number keys and two equivalent register sets 7 similarly arranged. 7

Only one register set, generally called the A register, to the right-hand of the drawing of Figs. 2 and 3, is shown in detail. The second register of the position, called: t'he"l3 register, is indicated by a few elements,

which as will be seen'later, have exactly the 7 same functions as the corresponding ele-; ments shown on the A register. In order, when both register sets are free, to give privilege to one of themv there is a single difference in the wiring of their circuits in that on the B register the back contact of relay 3-71 isconnected to the front contact of the relay 372, whereas the same connection be tween the contacts of the corresponding relays 304 and 305 on the A register is omitted.

By-rearranging the wiring to open this con nection on the B register and introduce it on the A register, the registers may be reversed and back contact of relay37l of the B regis ter. A similar circuit over the left-hand contact of key-201for relay 203; is attempted but is kept opened on the front contact of relay 305. Relay202 is maintained operated in acircuit over the right-hand contact, of

the forced release key 20 1, the righthand front contact and winding of relay 202, winding of relay 205, common wire 222, and winding of relay 304l,toground at the make-before-break contact ofrelay 306. Over the left-hand front contact of relay 202the calling lamp 206 and the guarding lamp 207.

are connected to an interrupter212 and display flashing signals. before theoperat'or-L The energization of relay 205 prepares, over its front contacts, the connection of the'trunk line with the common leads 221 and 223 of the fundamental circuit in which the stepping relay 307 is included and-which,

at this time is kept open'at the contact of relay 308 of the register and at contact of relay 208 on the trunk line. The, energization of relay 304 causes, in a circuit over its front contact, the energization of relays 303 and309. The described circuitover the righthand contact of key 201 is now opened at back contact ofrelay 303 so that at this time on the depression ofthe assignment key of another trunk line a connection withthe registers is not possible and an erroneous depression of another as signment key during the time the number keys of the position are used for one call is The magnetic holdingmeans 4110f the number-keysare without disturbing effect.

now energizedin a circuit overbackcontact of relay 305 and front. contact of relay 309, and the number keys when depressed are, in a well known manner, magnetically held in their depressed positions. -Each register set contains a series ofnumber relays412, 413 and 414 corresponding to the units, 10sand 100s number keys. Since the capacity of a satellite inthe arrangement shown does not exceed 2000 lines,

separate number relays are not provided for the 1000s keys,'and some of the counting relays, as will be shown later, are utilized to perform also the function of lJIZLDSlZllIlOIL One number relay is. provided for each pair of 100s keys, and by means of a relay 311 the translation of the decimal numbers depressed on the number keys to the automatic switches arranged in a different numerical system is secured. The number keys are 'each provided with two contacts which are utilized to control over their right-hand contacts the corresponding number relay on the A register and over their left-hand contacts the corresponding number relay of the B register.

The B operator proceeds with the depression of her number keys in accordance with the numerical designation of the desired line without waiting for the A operator to plug into the jack of the assigned trunk. Assuming that the number of the required line is 2222 the B operator depresses the four number keys, 415, 416, 417 and 418, in the third row from the top. Relays 412 and 321 are energized in a circuit over contact of key 415, wire 421, the left-hand winding of relay 321, left-hand back contact of" relay 312 and right-hand front contact of relay 303. In similar circuits are energized relays 413 and 322 over contact of key 416 and wire 422, and relays 414 and 323 over contact of key 417 and. wire 423, whereas relay 324 is energized in a circuit containing the contact of key 418, wire 424, and the right-hand back contact of relay 312. The energization of the number relays 412, 413 and 414 is maintained over their left-hand front contacts, the corresponding wires 425, 426 and 427, the front contacts of the corresponding relays 321, 322 and. 323 and front contact of relay 303. Over the right-hand contacts of the relays 321, 322, 323 and the left-hand contact of relay 324 a circuit is closed includingrelays 313, 314 and 315, which are energized. This circuit leads from battery. through the winding of relay 313, front contact and left-hand armature of relay 324, right-hand armatures and front contacts of relays 321, 322 and 323, through the windings of relays 314 and 315 to ground. Relay 313 provides a holding circuit for the right-hand windings of the relays 321, 322, 323 and 324, in series with the winding of relay 305, which relay is energized and disconnects the magnetic clutches 411 so that the number keys are rendered free. The common test wire 224 of the B register is now connected over the front contacts of relays 305 and 309 to ground so that from now on by the depression of an assignment key a trunk line can be connected to the B register. In parallel to the holding circuit described for relays 321, 322, 323 and 324 is connected the winding of relay 312, which is energized, disconnects the operative windings of the above-named relays and produces over its front contact the energization of relay 308. The fundamental circuit is now prepared at the contact of relay 308 and the register &

'is ready to control the group selector on the incoming end of the trunk shown on the left-hand side of Fig. 4. The selection cannot proceed, however, unless and until the A operator has inserted the connecting plug in the jack of the assigned trunk line.

The relay 209 is energized in a circuit over left-hand contact of key 204 and the sleeve of the plug on the A operators position. As it may happen that the B operator has in the meantime already depressed the number keys and the fundamental circuit has been prepared on the register, as described, assurance is made that no closures and openings of the fundamental circuit occur until the plug is fully brought into the jack, as otherwise it could happen that during the bringing in of the plug, relay 209 may, after its first energization, become denergized for a brief interval. To secure this, the energization of relay 208, which controls the closure of the fundamental circuit, occurs in a circuit over the front contact of relay 209 and the tip of the plug to ground on the cord. Relay 208 is provided with make-before-break contacts and when operated disconnects its right-hand winding from the spring of the jack and connects it over the right-hand contact of relay 209, the left-hand front contact and left-hand winding of relay 208, winding of relay 211 to the left-hand contact of relay 209 and ground. It may be observed that unless the assignment key 201 has been depressed to operate either of the relays 202 and 203, the above traced circuit which is closed for the relay 208 by the insertion of the plug at the A operators board is short-circuited, and relay 208 thus remains deenergized until said assignment key has been operated. This short-circuit which prevents the operation of the relay 208 may be traced from battery, right-hand contact of key 204, righthand armature and back contact of relay 202, left-hand armature and back contact of relay'203 to ground over the tip of the A operators plug in shunt of the circuit through the right-hand winding of relay 208. Relay 211 is also energized and disconnects the guarding lamp 207 so that only lamp 206 remains flashing, indicating to the B operator that the A operator has made the connection with the assigned trunk and the selection. is progressing.

A metallic circuit is now established over the two-wire trunk line 230 containing relay 501 and contacts 502 and 503 of the sequence switch 504 pertaining to the group selector, both wires of the trunk 230, the right-hand front contact of relay 208, both front contacts of relay 205, common wires 221 and 223, both back contacts of relay 318, back contact of relay 319, front contact of relay 308 and winding of stepping relay 307. The energization of relay 307 causes the operation of thev counting relay 325, which corresponds to the operated hundreds number relay 414 the circuit passing'over back contact of relay 316, front contact of relay 307,, left-hand back contact, of relay 331,-.

wire 428, right-hand contact of relay 414 and back contact of relay 335. Relay 325 provides a holding circuit over its winding, relay 335., front contacts of relays 325 and 314,.back contact of relay 341 andfront contact .of relay 304. Relay 335 remains shortcircuited over; front contact of relay 307.

The energization of relay 501 provides a Y circuit over its front contact, contact 507 top of the sequence switch, to its magnet 504. The sequence switch starts from position 1 and movesintoposition 2, controlled inthe well known manner over its localrcontact- 508. The magnet 510 of the trip. spindle is now energized in a circuit over sequence switch contact 509 top and front contact of relay 501. The trip spindlerotates and in the well known manner produces between each, step the short-circuiting of relay 307 in the fundamental circuit over the contacts 511, and sequence switch contact 512 bottom. Then relay 307 is so deenergized relay 335 becomes energized, and extends over its front contact the counting circuit to the following counting relay 326. whichfbecomes energized as soon as. the short-.circuiting of relay 307 1 s opened at the contact 511 of the tripspindle and this relay is again operated. On the last short-circuiting of the stepping relay,

relay 319 is operated and opens. the fundamentalcircuit so that relay 501 is .decnen gized' as soon as contacts511 are opened. The. trip spindlemagnet 510. is now disconnected, whereas sequence switch 504, energized in a circuit over back contact of relay 501 and sequence switch, contact 513 bottom,

is started from position 2 and moved into its position 5. In leaving position 2 the'trunk line 230 is disconnected on the sequence switch contacts 502 and 503 bottom fromrelay 501 and ground respectively and-connected over the same sequence switch con-v tacts top to the left-hand windingsof the repeating coil 514 and therelease relay 516. The supervisory relay 517 is now locally onergized in a circuit over the-sequence switch contact 518 bottom, andmaintains the rightha-nd hi -h resistance winding of relay 516.

short-circuited. The power magnet 519 of the brush carriage is now energized in. a circuit over sequence-switch contact 521 bottom. and back contact of test relay 522., The

power magnet moves the brush carriagein the well known manner along theterminals on the row selected by the set position of the trip spindle, and. the high resistance. winding of test relay 523, is connected over the sequence switch contact 524 bottom, with the -test brush 525, during the search for a tree trunk.- line to a final selector.

' Simultaneously with the energizat'ion of relay 31 9 on the register, relay338 is also energized and causes theenergization of re,-

lays 316 and 332 in acircuit over front con tacts of relays 304 and 338; and. right-hand back contact of relay 331.- Relay 332 vides over its left-hand front contact a holding circuit for its winding, but relay 331 which is connected in this circuit, being shunted by the low resistance winding of relay 316', remains deenergized. The slow opcrating relay 316 provides over its front C011,.

tact the short-circuiti ng of relay 315 which when deenergized causes the operation of the slow-operating relay 317 in: a. circuit over back contact of relay. 315a'nd front contacts of relays 324, 305 and 309. In parallel to relay 317 is placed the left-hand winding of relay 3.18 which also operates, Relay 317' provides on its front contact a short-circuit of relay 314 whichwhen deenergized opens the holding circuit for the counting relays. Relay 319. again closes on its back contact the fundamental; circuit, 5 The shunt 340.

placed around. the winding of relay 338'se cures that this relay, when deenergized, closesi-ts back contact after all the counting relays have been deenergized. When on the front contact, of relay 338- the shunt'around the winding ofrelay 331 is. opened, this relayis energized, disconnecting at its left hand contact the counting circuit controlled by the stepping: relay from the sv number relays andconnecting it over its left-hand front contact and the left-hand back contactof relay 333 and wire 429 to the 10s number relays. Relay 316is disconnected on the righthand contact of relay 331 from relay and connectedto, relay 334. Relay 316 when deenergized opens the shortcircuit around relay 315, which again energizes,

causing thev deenergization of relay 317 and which preparesagain the holding circuit for the counting relays. a

, Relay 318which has beenenergized at the particular moment described, disconnects the stepping relay from the trunk line and introduces the battery and relay 342 in the circuit of the trunk line, whereby the slow acting relays 316 and 315, control the moment ofoperation of relay 318, so that thc change in the circuit of the trunk'lineis made at this point after the sequence switch this in turn the energization of relay 314,

gized, disconnects, on its back contact the operative winding of relay 318 and, maintains itself operated over its front contact until the register is released.

it will be seen that relays 516 and 342 are included in a circuit in series with. each other as soon as sequence switch contacts 503 and 502 are closed in position 3. At this same instant the circuit for supervisory re lay 517 is also closed over sequence switch contact 518' bottom. Relay 517, by operating, short-circuits the high resistance winding of relay 516 thereby permitting both relays 342 and 516 to energize. Relay 516, by operating, closes the circuit from battery through the winding of relay 501 to ground, at the armature and contact of relay 516. Relay 501 thereupon attracts its armature and opens the above traced circuit which started sequence switch 504 out of position 2 such that when said sequence switch arlives in position 5 it will come to rest, and close the circuit for power magnet 519 to initiate the trunk hunting movement as above described.

When the brushes of the group selector reach the terminals of a free final selector the left-hand high resistance winding of test relay 523 is energized in a circuit over sequence switch contact 524 bottom, test brush 525, contact 546 of the final selector sequence switch 534 and resistance 545. Be lay 523 connects, over its front contact, its low resistance winding, the winding of the 2nd test relay 522 to the 3rd brush 525 making the selector trunk line test busy in the well-known manner. The high resistance release relay 547 on the final selector, which is connected in parallel to resistance 545, is thereby also energized. The energization of relay 522 causes the disconnection of the power magnet 519 and also energization of sequence switch 504 in a circuit over its contact 513 bottom and front contact of relay 522. In parallel to the sequence switch is connected over its contact 507 bottom the holding magnet 505 of the brush carriage, which is arrested, whereas the sequence switch starts from position 5 and moves over position 6 into position 9. On sequence switch 504 leaving position 5 relay 516 is disconnected at the sequence switch contacts 502 and 503 from the trunk line which is, in position 9, extended over the sequence switch contacts 526 top and 527 bottom,-the brushes of the group selector, the sequence switch contacts 531 top and 532 top to relay 533, of the final selector and to ground respectively, thus preparing the fundamental circuit on the incoming. endat the final selector. 1n reaching position 8 the sequence switch contact top connects relay 522 direct with the brush 525. The right-hand winding of relay 523 is thereby short-circuited and this relay is deenergized. When the sequence switch 504 passes position 8 relay 533 is operated over the sequence switch contact .tates.

513 top and contact 508 to ground, the contact 513 being closed before and opened after contact is closed. The relay 533 is thus energized in a preliminary energizing circuit closed as soon as sequence switch contacts 513 and 527 reach position 8, and due to the fact that contact 513 does not open until slightly after contact 526 closes in position 9, relay 533 is maintained energized until after the fundamental circuit is closed at contact 526. This insures the operation of relay 533 under all circumstances when a connection is made with a free final selector, and, as will be shown later, secures the proper release of the switches on a premature release.

When the contacts 502 top, and 503 top, are opened after the sequence switch 504 leaves position 5, the relay 342 on the register is denergized and the right-hand winding of relay 318 is opened, so that after the deenergization of this relay the fundamental circuit on the register is again closed. This takes place before sequence switch 504 reaches position 8 and the fundamental circuit is extended to the final selector. As soon as the passing contact 513 top is opened in position 9 of sequence switch 504, the stepping relay 307 is energized in the fundamental circuit, causing the energization of the counting relay 326 in a circuit over back contact of relay 336, right-hand front contact of number relay 413, wire 429, back contact of relay 333, front contact of relay 331 and front contact of relay 307. Relay 326 prepares its holding circuit over relay which remains deenergized as long as the stepping relay is operated. 4

Relay on the final selector when energized provides a circuit for the sequence switch 534 over front contact of relay 533 and sequence switch contact 535 bottom. The sequence switch starts and, controlled by its local contact 536, moves into position 2 in which the magnet of the trip spindle 540 is energized in a circuit over sequence switch contact 544 bottom and front contact of relay 533, and the trip spindle roiVith each short-circuiting of the fundamental circuit at the trip spindle contacts 537 over sequence switch contact 538, the stepping relay 307 on the register is deenergized and the counting relays are operated in succession, as hereinbefore described. vVhen relay 319 is again operated the fundamental circuit is opened and relay 533 is .deenergized as soon as contact 537 top is opened, the trip spindle magnet is disconnectedand the sequence switch 534 is energized in a circuit over back contact of relay and sequence switch contact 539 top. Sequence switch 534 moves into position 5. n the meantime relay 338 is operated and uses the energization of relays 316 and 354. In consequence relay 3-15 is deener- 'gized, relay 317 is energized and relay 314 is deenergized, and the holding circuit for the counting relays is opened. The fundamental' circuit is again closed on the back contact of relay 7 lays 316, 315, 317an'd 314 in succession se- 319. The operation of recures such a timed control that the reclosure "of the fundamental circuit is made certain before the sequence switch 534 of the final reaches position 5, but only after th1s sequence switch leaves its position 2 and the trip spindle magnet'has been disconnected on contact 544, whereby the difference in these times is selected so as to insure a safe operation under all variations in the speed of the switches, voltage, etc. The four slowacting relays 316, 315, 317 and 314, are ar ranged in pairs of slow-operating and slo'wdeenergizing relays, relays 316 and 317 being slow to energize and relays 314 and 315 slow to deenergize, in such manner that a minimum of variation in the time of their combined action is secured. If the voltage is higher and the slow-operating relay 316 operatesquicker, the short-circuited relay 315 is deenergized slower, and vice versa. A. similar relation is secured in the time of the'coeperation' of relays. 317 and 314, it

being remembered that all four relays in succession control the time for the changingov'er of the fundamental circuit from the "10s to-the units impulses, whereas only the relays 316' and 315 control the time for the counting relaysfrom wire 429' and pregpa'res a new controlling circuit over wlre 430, so that as soon as relay 316 has made,

its back contact, relay 326 is energized in a circuit over back contact of relay 336, front contact of relay 412 wire 430, back contact of relay 344, front contact of relays 333, 331 and 307, and back contact ofrelay 316.

When the sequence switch 534 reaches its position 5 it remains in such position since, as has been explained, the fundamental circuit is again closed prior to this time, and relay 533 energized to open the'circuit which drove sequence switch 534 out of position 2 andthe power magnet 550 which controls the movement of the brush carriage is energized in a circuit over front contact of relay 533 and sequence switch contact 541 top, and the brush carriage is moved in the well-known manner along the third terminal row short-circuitings of the stepping relay 30 7 in the fundamental circuit being again produced at contact 542 top of the brush carriage and'the counting relays on the register are operated a third time'under,

the control of the stepping relay. When relay 319 is again energizedthe fundamen- V 'tal circuit is-opened, and as soon as contact 542 is also opened relay, 533 is deenergized, the power magnet 550-is disconnected and the sequence switch 534 is again energized and moves from its p0siti'on'5 into its position 10. The holding magnet 560 which is now connected in parallel to the sequence switch over contact 543 bottom, is also 'energized and'the brush carriage is arrested wlth the brushes'on the wanted 11116. After 7 the sequence switch 534' leave's position 5 the resistance 545 is disconnected at contact '546 and relay 522 at the group selector is cleenergized. The sequence "switch 504 is there by energizedin a circuit 'ove'r backcontact of relay 522'and sequence switch contact 521 top, and moves into its position 14. After leaving position 9 the metallicthrough connection to the final selector is openedon the sequence switch " contacts 526 and 527, and

in position 12 the corresponding brushes of the selector are connected over the salmetequence switch contacts with the "transmitter battery supply over the right-hand windings of the repeating coil 514 and the supervisory relay 5l7. The release relay 5.16 and the left-hand w'indingsfof the repeating coil are again brought into connection with the "trunk line over sequence switchcontacts 502 'and503,, 'r- V s,

In the meantime the last energiza'tion' of relay 338'0n the register causes the energiza- .tion of relays 316 and 306 in a circuit over the, right-hand front contactsof' relays 331 and The holding circuit'for the relays 304, 205 and 202 is'thereby maintained over the'left front contact of relay 306, front contact ofrelay 314, back contact 'ofrelay 341 and front contact of relay 304. The make-before-break relay. 306 provic'les a 'locking circuit for its right-hand win-dingover its right-handfront contact and front contact of relay 303.

The opening of the holding circuit for the counting relays is again controlled through the operation of the, relays 316, 315, 317 and 314 Sin succes} sion. The opening of the circuit which contains relays 304, 205 and 202 takes-place "at the same moment; Relay 205 when deenergized disconnects the, trunk line from the common leads 221 and 223' and provides both its back contacts and both back contacts of relay 213; withthe tipfa'nd the ring "I20 a through'connection of the trunk lines over ofthe connecting plug, whereby the moment fof this through connection is again regulated by the timing relays 316, 315, 317' and 314, softhat-th'e through connection takes place after relay 533 on the finalselecto'r has been disconnected on the sequence switch contact 531 from the trunk but before the sequence switch 504 of the group selector has reached position 14. Relay 516 is now energized in a metallic circuit containing the battery and supervisory relay in the cord of the A operators position, and prevents the release of the group selector. The deenergization of relay 202 causes the lightin of lamp 206 in a circuit over left-hand back contact of relay 202, right-hand back contact of relay 203, and left-hand front contact of relay 209. The right-hand winding of relay 208 is now short-circuited over the other back contacts of relays 203 and 202, but the left-hand winding of relay 208 remains energized in the circuit previously described and maintains the operation of this relay for the duration of the connection. The denergization of relay 304 causes the release of all holding circuits on the A register. Relay 303 being deenergized again prepares on its back contact the test circuit for the trunks to the A register which can now be used for a new call provided either that the B register is free and its relay 371 cleenergized, or that the B register is busy but its relays 372-and 373 are energized after the number has been set up on the keys for the trunk connected with the B register.

When the sequence switch 534 of the final selector reaches position 8, the wanted line is tested and if found free the right-hand high resistance winding of test relay 551 is energized in a circuit over the cut-off relay 552 of the wanted line, the test brush 553 and the sequence switch contact 554. The left-hand low resistance winding of the test relay 551 and the 2nd test relay 548 are brought into circuit in parallel to the high resistance winding of relay 551 and the wanted line is made busy. When reaching position 10, the magnet of sequence switch 534 is maintained energized in acircuit over back contact of relay 533, front contact of relay 548 and sequence switch contact 539 bottom, and moves over positions 10 and 11. In position 12 an alternating ringing current is immediately sent to the station of the wanted line in a circuit over the sequence switch contacts 555 and 556 and the ringing relay 557. Relay 533 is connected over sequence switch contact 558 with a common interrupter 559, which, when closed, causes the energization of relay 533 and, in consequence, the sequence switch 534, over a circuit including front contact of relay 533 and sequence switch contact 535 bottom, which sequence switch moves into its position 13 in which relay 533 is connected over contact 531 bottom, with a further common interrupter 561. The two interrupters 559 and 561 are continually operated and are arranged to close for a short time the circuit to ground at pro-determined time intervals, so that after the sequence switch 534 reaches position 12, it is brought, after the lapse of a few seconds, over its positions 12 and 13 into position 14. The duration ofv time in which sequence switch 534 remains in these positions and an instantaneous ring is sent to the wanted station depends upon the moment the sequence switch reaches position 12 and slightly varies according to whether at this moment the interrupter 559 has just assed its contact or is near to it. The contact on theseinterrupters is closed for a short time sufiiclent to energize relay 533 and in consequence the sequence switch 534 but not sufficient to maintain its energization for more than to move the sequence switch over one position. In this manner the sequence switch 534 is at least held in position 13 for the time which elapses between the closure of the interrupters 559 and 561. After se quence switch 534 reaches position 14, the direct connection of the ringing current is removed by the opening of sequence switch contact 555, and the connection with the source"of ringingcurrent is now maintained with the line over sequence switch 00115225 562 and the interrupter 563, which, in selected time intervals, connects periodically either the ringing current or ground. to the line. As soon as th receiver at the wanted stationis lifted from the hook, the ringing relay 557 is energized and causes,'ovei its front contact and sequence switch conta t 535, the energization of sequence switch 534, winch starts from position 14 and moves into its position 15 in which the ringing current is disconnected from the line which 1s now through connected over sequence swith contacts 562 and 556 to the transmitter current supply at the group selector. R-elay517 is energized and iii shortcircuiting the high-resistance winding of relay 516 transfers the supervision to the supervisory relay on the cord on the A operators position.

If instead of calling an even thousand, a number is required in which the 1000s digit is odd, the following change in the opera tion of the register on the semi-automatic l3 operators position takes place. ASSUTfliIW' that the wanted number was. 1222, instead of depressing the number key 418, the operator would have then depressed the number key '19. The circuit for the left-h and winding of, relay 324, in this case, is established over back contact of relay 337 and winding; of the counting relay 327, which relay oper ates and provides a holding circuitfor its winding over the winding of relay 337, but relay remains for the present deenergized, being short-circuited by the low resistance winding of relay 324. When, as has'been described, the number keys are released and the operative winding of relay 324 is opened on the right-hand contact of plete under the control of the 100s number relay 312, relay 337 becomes energized. It

' relays is nowreduced by one and the trip spindle will be arrested to release the brushes of an odd level. I If for example the wanted number depressed on the number keys was 2322', key

420 isdepressed instead of key 417. The I [326 has made itsfront contact and has same relay 414 is operated, as described before, but itsoclrcuit 1s nowextendedover the left-hand winding'of relay 31 1 which when energized, provides a holding circuit over its righthand winding and the left-hand winding of relay 344jover the front contact of relay 311, back contact of relay 341, to

the front contact of relay 304'. After the second series of impulses is-completed as described, and relay 333 is'operated, the units impulses are not extended over wire 430 to the contact of the energized unitsnumber relay 412, but are directedvover the left hand front contact-ofrela'y 344 direct to the'lst counting relay on the right of Fig. 3*. The brush carriage of the final when rotating,,makes.,a series of eleven shortcircuitings until all the counting relays to the left of the one initially energized are operated and the brush carriage moves thereby over all the terminals of the first hundred and to the terminals of the second hundred.- During the time the final. selector brush carriage is making the comparatively long step between'the first and second half of the terminal row, the following operations take placeon the relays of the register,

a The operation of relay 319 remains without influence on the fundamental circuit vsince relay 307 remains short-circuited atthe final selector.- On the other hand the operation of relay 338 causes the energization of relay 345 in a circuit over front contacts of relays 338, 331, 333 and 344 and right-hand winding of 344 Relay 316 which is in the same circuit, starts to energize, but, as Will'be seen later, it is disconnected before the series of the timing relays can affect the funda- Relay 345 over its front contact provides for the energization of relay 341, which opens at its back contact the circuit for the holding winding ofrelay 311, and as this circuit is also opened on the backc'ontact of relay 338, relay 311 is c deenergized; The holding circuit of the counting relays is thereby also opened at back contact of relay 341. All counting relays are now deenergized. As has been preashas been described;

messes At the moment relay 338 closes its back contact; the counting relay 326 is again" energized in a circuit over contact of relay-336, front contact of relay '412,-wire.430, front contact of relay 341, back contact of relay 338-, and front contact of relay 304. In the meantime through the opening of the front contact on relay 333, relay 345 and, inconsequence, relay 341 begin to" dcencrglze' These relays are so timed that relay 341 leaves its front contact after it has been assured that the counting relay locked itself up with its corresponding relay 336, which is energized as soon as relay 341 opens its front contact. The described series of operations of I the -relays of the register takes place before "the short-ci'rcui'ting contact on the brush carriage of the final selec-' duced in: the fundamental circuit on the final selector are" now transferred tog'counting relays ,ofthe register over wire 430 and 7 back contact'o-f relay 344, as. hasbeen described, and when relay 319 is again oper-' ated, the fundamental circuit is finally I 7 opened, whereas the 'energization' of relay 338 provides the disconnection of the register and the throughconne'ction of the trunk,

I I The eleventh shortcircuiting of the fundamental circuit has been utilized forthe first deenergiz'ation of the counting relay, andthe continuation of the short-circuiting in the second half of the terminal row would bring the final selector onestep too far, were it not that this has been avoided through the local energization of the first -'count1ng relay for/the second half of the impulse series as described;

Afterthe conversation is completed and the clearing outlamps'have been displayed onthe' A operators POSltlOH, she 1s able to break down the connection by withdrawing the plugs from the jacks of the calling line and the trunk line. This causes the release of the automatic switches in the satellite I and the restoration of the relays on the outgoing end of the'trunk to their position of rest without the aid of the semi-Boperator.

After theplug is withdrawn from the ack, relay 209 is denergized and opens at its front contacts the holding circuit of'relays 208 and 211. Relay 516 is alsodeenergized mg position 14 the brushes are, isolated at the correspondlng sequence 'swlt'ch contacts 524,527 and 526, and the release of the final selector 7 is I started; Nhen the 7 sequence I switch 504 reaches position the power 1 30 "85 tor has been opened. Further impulsespr"omagnet 519 is again energized in a circuit over sequence switch contact 521 bottom and back contact of relay 522, and the group selector brush carriage is moved into its home position, on reaching which relay 522 is energized in a circuit over home contact 520 of the brush carriage and sequence switch contact 518 top. The power magnet 519 is disconnected and the sequence switch 504 and holding magnet 505 are energized in a circuit over the front contact of relay 522. The brush carriage is arrested and the sequence switch 504 starts from position 17 and moves into position 1. The restoration of the trip spindle has already taken place after the brush carriage has been set in a circuit over sequence switch contact 509 bottom and contact 511 bottom of the trip spindle, as soon as the sequence switch 504 reached position 8.

l/Vhen the test brush 525 is isolated as just described, relay 547 becomes deenergized and sequence switch 534 is energized in a circuit over its contact 543 top and the back contact of relay 547. The sequence switch 534 starts from position 15 and moves into position 17 in which relay 533 is brought into connection with the. wanted line over sequence switch contacts 555, 556 and 532. As the called subscriberhas re stored his receiver, and the called line is opened to direct current relay 533 remains deenergized and the sequence switch 534 is maintained energized over back contact of relay 538 and moves over position 17 into position 18 in which the power magnet 550 is again energized in a circuit over the back contacts of relays 533 and 548 and sequence switch contact 541 bottom. The brush carriage is moved to its position of rest and, on reaching its home contact, relay 533 is energized in a circuit over sequence switch contact 558 top and home contact of brush "carriage 542 bottom. The power magnet of the brush carriage is disconnected whereas the sequence switch 534 together with the holding magnet 560 is again energized in a circuit over front contact of relay 533, as described. The brush carriage is arrested and sequence switch 534 starts from position 18 and moves into its position 1. The restoration of the trip spindle has been already effected oversequence switch contact 544 top and trip spindle contact 537 bottom when the sequence switch 534 reached position 12. I If after the release of a connection the trunk is immediately assigned for a new call and assuming that theB operator would be able to complete the assignment of the trunk and the depression of the number keys be fore the brush carriage of the group selector and its sequence switch have returned to their position of rest, the fundamental circuit is maintained opened on the contacts 502 and 503 of the sequence switch 504 and the register is kept waiting until these contacts are closed in position 1 of sequence switch 504.

If the wanted line has been found busy and during the time sequence switch 534 passes position 8 relay 551 does not become energized, the sequence switch 534 is arrested in position 10 in which the operative winding of relay 551 is disconnected at setion 10 and is arrested in position 11, in.

which the power magnet of the brush carriage 550 is energized in a circuit over con tact 341 bottom as described and the brush carriage is moved into its home position with the brushes opened. In reaching the home position relay 533 is operated over home contact 542 as described and sequence switch534 is again energized and started from position 11. In positions 12 to 16 the sequence switch 534 is now maintained energized over back contact of relay 547, in position 17 over back contact of relay 533 and in position 18 over front contact of relay 533. The sequence switch 534 therefore moves directly into position 1.

Disconnection however can take place at any moment desirable during the progress of the selection, either through withdrawing the plug from the jack of the trunk line as described, or through the use of forced re-- lease key 204 provided on each trunk on the B operators position. If the B operator. for example, notices before the selection is completed that she has made a mistake, she depresses the key 204 and opens on its rightvhand contact the holding circuit for relays 202, 205 and 304, if the connection has been made with the A register, or the holding circuit of relays 203, 213 and 371 it the connection has been made with the B register. At the left-hand contact of key 204 is opened the circuit forrelay 209, which in turn opens the circuit for relay 208. The relays on the register and on the outgoing end of the trunk line are therefore restored to their condition of rest, and in depressing the assignment key' a second time the operator can repeat the call. 7

If a premature release happens during the time the group selector is searching the terminals for a free final selector, relay 516 circuit and a selectively operable switching device for interconnecting two of said lines, an operators key-board; a plurality of register sets each comprising a set of number relays, a set of counting relays and a set of switching relays; means under the control of said key-board for variably operating the number relays of any one of said plurality of register sets, means jointly controlled by said switching device and the operated number relays for variably operating the associated counting relays, means controlled by said counting relays for operating the associated switching relays, and means jointly controlled by said plurality of register sets for associating said connecting circuit with a certain one or" said register sets.

4. In a telephone exchange system, a plurality of lines, a plurality of selectively operable switching devices for interconnecting two of said lines, a sender for controlling the operation of said devices, a relay for coiiperating in the control of one of said devices, a controlling switch for another 0t said devices, an energizing circuit for said relay, means operated by said switch during its controlling operation for closing and then opening said energizing circuit, a second circuit for said relay including a contact at said sender, and means operated by said switch for closing said second circuit prior to the opening of the first mentioned energizing circuit.

In a telephone exchange system, a plurality of lines, a plurality of selectively operable sv itching devices for interconnecting two of said lines, a sender for controlling the operation of said devices, a relay for cooperatingin the control of one oi? said devices, an energizing circuit for said relay, means under the sole control of said one of said devices and another one or" said devices for closing said energizing circuit,-another energizing circuit for said relay, and a contact at said sender for closing said last mentioned circuit.

6. In a telephone exchange system, a plu rality of lines, means including a connecting circuit and'a plurality of selectively operable switching devices for interconnecting two of said lines, a sender for controlling the operation of said devices, a relay associated with one of said devices for cooperating in its control, an energizing circuit for said rel y, means under the sole control of said one of said devices and another one of said devices for controlling said energizing circuit, another energizing circuit. for said relay, and two switches, one associated with said connecting circuit and the other with said sender, for controlling the last mentioned energizing circuit.

,7. In a telephone exchange system, a plurality of lines, means including a switching device for interconnecting two of said lines,

means including a controlling device for causing said switching device to perform two selective operations in succession, means for variably operating said controlling device in successive stages, a controlling circuit'between said controlling device and said switching device, and a slow-to-energize and a sloiv-to-decnergize relay for controlling said circuit.

8. In a telephone exchange system, a plurality of lines, means including a switching device for interconnecting two oi said lines, means including a controlling device for causing said switching device to perform two selective operationsin succession, means for variably operating said controlling device in successive stages, a controlling circuit between said controlling device and said switching device, a slow-to-denergize relay for controlling said circuit, and a slow-to-energize relay for controlling said relay.

9. in a telephone exchange system, a plurality of lines, means including a switching device for interconnecting two of said lines, means including a. controlling device for causing said switching device to perform two selective operations in succession, means for variably operating said controllingdevice in successive stages, a controlling cir cuit between said controlling levice and said switching device, and a plurality of slow-toenergize and slow-to-deenergize relays for controllingsaid circuit.

10. in a telephone exchange system, a plurality of lines, means including a plurality of switching devices for interconnecting calling and called lines, a sender for controlling the cperation of said switches in accordance with the numerical designation of the called line, switching means for causing said sender to control the switching devices in accordance with the successive digits of the called number, and a slow-toenergize and a slow-to-dcnflgize relay for controlling the operation of said switching means.

11. In a telephone exchange system, a plurality of lines, a selectively operable switching device -for interconnecting two of said lines, electromagnetic operating means for said device, an operators position, a circuit extending from said position toward said electromagnetic operating means, a keyboard and a set of counting relays at said position, means controlled by said switching device during its operation for causing the gradual operation of all of said counting relays, means controlled by the keys of said board for determining the number of the counting relays to be actuated, and means at said position for delaying the operation of the last mentionedv means until the said means controlled by the switching device has operated all of said counting relays.

12in a telephone exchange system, a plurality of lines, a selectively operable switching device for interconnecting two of said lines, electromagnetic opera-ting means ior said device, an operators position, a circuit extending from said'position toward said operating means, a keyboard and a set of counting relays at said position, means controlled bysaid switching device during its operation for causing the gradual operation of all of said counting relays, means con lectively operable switching device, a set of counting relays for controlling the operation of said device, energizing and locking circuits for said relays, means operative upon the actuation of a certain one of said countring relaysfor opening said locking circuits, 'means for preventingthe operatlon of said means, and separate means for opening said locking circuits- 14. In a telephone exchange system, a plurality of selectively operable switching devices, a set of counting relaysfor controlling the operation of said devices, energizing and locking circuits for said relays, means actuated upon the operation ofone of said relaysin controlling one of said switching devices'for opening said locking circuits, change-over means" operated upon the opening of said locking circuits for vcausing said relays to] control another one of said devices, separate means for opening said locking circuits, and means controlled by said separate means for preventing the operation'of said change-over means.

15. In a telephone exchange system, subscribers lines, a connecting circuit, automatic switchesv for extending said circuit to interconnect said lines, a controlling mechanism for governing the movement of said switches, and a set of relays operative to associate said controlling mechanism with the automatic switches and also serving to complete said connecting circuit, said relays being effective to complete the connecting circuit only after having operated to associate the controlling mechanism with the automatic switches.

16. In a telephone exchange system, subscribers lines, a connecting circuit, auto- -Inatic switches for extending said circuit to interconnect said lines, a plurality of impulse controlling mechanisms for governing the movement of said switches and a set of relays operative to associate an idle one trolling mechanism for governing the move- 4 ment of said switches, and a set of relays operative to associate said controlling mechanism with the connecting circuit and also serving to completethe connecting circuit,- said relays being effective to complete the connecting, circuit only after having operated to associate the controlling mechanism with said connecting circuit. 7. i I r 18. In a telephone exchange system, subscribers lines, a connecting circuit, means including automatic switches for extending said connecting circuit to establish a connection between said lines, a pluralityrofcontrolling mechanisms for governing the movement of said automatic switches, and a set of connecting relays operative to asse ciateone of said mechanismswith'the con;- necting circuit and also serving to complete said connecting circuit, said connecting relays being effective to complete the connecting circuit only after having operated to associate a controlling mechanism therewith.

19. In a telephone exchange system, subscribers lines, a connecting lcirouit, fauto matic switches for extending said'connecting circuit to interconnect the subscribers lines, a plurality of controlling mechanisms for governing the movement of the automatic switches, said mechanisms being arranged to be taken for BS0111 a definite order, and a set of connecting relays operative to associate an 1dle one of said mechanisms with said connecting circuit and also serving to complete the connecting circuit, said relays belng effective to complete the connect ng clrcult only after havmg associated a controlling mechanism therewith.

20. In a telephone exchange system, subscribers lines, a connecting circuit, automatic switches 'for extending said circuit to interconnect said lines, acontrolling mechanism for-governing the movement of said automatic switches, and a relay operative,

.to associate said mechanism with the autoextending said trunk to interconnect said lines, an operators position, a switch controlling mechanism at said position, means under the control of the operator for variably setting said mechanism, and a relay arranged when energized to connect the controlling mechanism-with said trunk to con-' trol the operation of said switches and arranged when de'e'nergized to complete said trunk circuit for conversation, said relay being effective to complete the trunk circuit only after having been energized and subsequently deenergized.

23. In a telephone system, an exchange, subscribers lines terminating therein, a second exchange, subscribers lines terminating therein, a trunk circuit betweensaid exchanges, means for connecting a calling line in the first exchange to said trunk, automatic switches in the second exchange for extending said trunk to a called line, impulse control mechanism at said first exchange, and a set 01": relays operative to associate said mechanism with the trunk to control the operation of said switches and also operative to complete said trunk circuit for conversation, said relays being effective to complete said trunk circuit only after having first connected the controlling mechanism therewith. V

24. In a telephone exchange system, subscribe'rs lines, an A operators position, a trunk circuit, a cord circuit at the A operators position for extending a line to said trunk, automatic switches for extending said trunk, a B operators position, a controlling mechanism, a set of relays operated under the control or the B operator to connect said mechanism to said trunk to establish a controlling circuit tor said switches, and a second set of relays operative to complete the switch controlling circuit and controlled jointly by the operation of said first set of relays and the insertion of the plug of the A operators cord circuit in the jack of said trunk.

25. In a telephone exchange system, subscribers lines, an A operators position, a trunk circuit, a cord circuit at the A operators position for connecting a calling line to said trunk, selective switches for extending said trunk, a B operators position, a controlling mechanism, a set of relays operated under the control of the B operator for connecting said mechanism to the trunk to prepare a controlling circuit for said switches, and a second set of relays for completing said switch controlling circuit and operated only when said first set of relays are operated and the plug of the A operators cord is fully inserted in the jack of said trunk circuit.

26. In a telephone exchange system, subscribers lines, an A operators position, a trunk circuit, a cord circuit at the A operators position for connecting a calling line to said trunk, selective switches for extending said trunk, a B operators position, a controlling mechanism, a set of relays operated under the control of the B operator for connecting said mechanism to the trunk to prepare a controlling circuit for said switches, and a second set of relays for completing said switch controlling circuit and operated only when said first set of relays are operated and the plug of the A operators cord is fully inserted in the jack of said trunk circuit, both of said sets of relays serving to complete said trunk circuit for conversation after the selective switches have been operated.

21'. In a telephone exchange system, subscribers lines, an A operators position, a trunlr circuit, a cord circuit at the A operators position for connecting a calling line to said trunk, selective switches for extending said trunk, a B operators position, acontrolling mechanism, a set of relays operated under the control or" the B operator for connecting said mechanism to the trunk to prepare a controlling circuit for said switches, and a second set of relays for completing said switch controlling circuit and operated only when said first set of relays are operated and the lug of the A operators cord is fully inserted in the jack of said trunk circuit, said first set of relays being arranged to deenergize after said switches have been operated and complete the trunk circuit for conversation.

in witness whereof, I hereunto subscribe my name this 11 day of July A. 1)., 1918.

LIPA POLINKOWSKY.

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