US1284996A - Semi-automatic telephone-exchange system. - Google Patents

Description

, AF. n.' M'CBERTY. SEMI-AUTOMATIC TELEPHONE EXCHANGE SYSTEM..

i APP-LlCATIQPJI FILED SEPT.I3.19I2. 1,284,996. l PatentedN0v.19,1913.

8 SHEETS-SHEET l.l

F.- n: Mesem.4 SEMI-AUTIOMATIC TELEPHONE EXCHAGE SYSTEM. APPLICATION FILE D SEPT. I3. I9| 2.y

1,284,996. .Patented L\"0v. 19,19^18.l

V s Sums-slim s.

j' Affy.

APPLICTIOILFILED SEPI. I3, ISI?. V -l Patented NOV. 19, 1918.

F. R. McBERTY. sEMLAuToMAnc TELEPHONE EXCHANGE SYSTEM.

APPLCATION FILED SEPTJS, |9I2.

Patented Nov. 19, 1918.

8 SHEETSSHEET 5.

lll/V/'nessesx @291, infra,

` Y r. n. mamy. SEMI-AUTOMATIC TELEPHONE EXCHANGE SYSTEM. APPLlc/mon mso sur. la, m2.

1,284,996.- Patented N0v.19,191&

W/fnessesf Y l /n yen for.' 0. En. @Jr/L Ffm/f Mceffy.

A F. R. MCBERTY. SENT-AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT. T3. l9l2. .1,284.996.l PatentedN0v.19,1918.

s SHEETS-SHEET 7.

kF. II. MCBEIIIY.,

SEMI-AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT. I3. I jIz.

- 1,284,996. Patented Nov. 19, 1918.

8 SHEETS-SHEET 8.

LKFI WIFI FIFIFIIFIIFI@ @III *IWL-g f UNITED sTATEs PATENT oEEIcE.

FRANK R. MCBERTY, OF ANTWERP, BELGIUM, ASSIGNORyBY MESNE ASSIGNMENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OFNEW YORK.

SEMI-AUTOMATIC TELEPHONE-EXCHANGE SYSTEM.l

Patented Nov. 19, 191s.

Application led September 13, 1912. Serial No. 720,169.

To all fw hom t 'may concern.'

Be it known that I, FRANK R. MOBERTY,

a citizen ofthe United States, and a resident of Antwerp, in the Province of Antwerp and Kingdom of Belgium, have invented new and useful Improvements in Semi-Automatic Telephone-Exchange Systems, of which the following is' a specification.

This invention relates lin general to improvements in telephone exchangeV systems for the interconnection of telephone lines, and has to do more particularly with systems in which the extension of the desired connection from a calling line to a called line is accomplished byautomatic selector switches, under the control of an operator at the central or switching station. Certain features to be described, however, are not restricted to systems of this character, being also applicable, as will be apparent to those skilled in the art, to systems of widely varying character, as, for example, to full automatic telephone exchange systems and, particularlythose features relating to the connection of a calling line with an operator, to manual telephone exchange systems.

One of the principal features of the invention has todo with the association of an operator with a connection to be Vextended for the purpose of receiving the instructions from the party calling, in accordance with which she will then act to produce the desired connection. To produce the best results in a system of this character, it is necessary thatmore than one operator should be able to control the establishment of any desired connection. For this purpose the in-v vention involves the distribution of calls to home or alternate operators, it being possible for either a home or alternate operator to control the establishment of any desired connection. In this system of distribution,

prepared to receive a call and establish thel desired connection, such circuit to be extended will be associated with such alternate' operator. The inventlon, therefore, may be idle, but if such operatorris-not idle 'being automatically associated with some other operator.

A further feature of the invention relates to the automatic distribution of calls, thlatl is, of circuits to be extended, notgonly to operators but also to one of a plurality of controlling equipments individual to such operator. A call coming in causes first the automatic selection of an idle'operator, and then the automatic selection of an idle con# trolling equipment of 'such operator, such selection causing the association with the circuit to belextended on` which suchl call has come inaof the equipment for controlling the establishment of the desired connection. l I Another feature of the invention provides means whereby every call coming into .a

semi-automatic exchange, in which calling lines are automatically connected to an 'operators position and are connectible to such, operatorif idle, will be indicated before such operator by a visual signal, such visual signal, although located on one operators position. being observable by a plurality of operators, any one of which may obtain access to the circuit to which the signal is individual, for the purpose of controlling the extension of the desired connection. Furthermore, the invention provides that all calls in the exchange connected to any operators position, and still unattended to, are simultaneously indicated. each by its own visual signal, so that at all times the number of calls awaiting attention will be apparent to each operator, and to the other operators to whom the circuits on which such calls have been received are accessible.

' A further feature of the invention provides that a circuit to be extended, having caused the selection of an idle operator and of an idle equipment of such operator. will.

be connected to the telephone of such operator and to such controlling equipment by separate and independent leads. B v such arrangement it is possible that, as soon as the operator has received the necessary instructions from the calling party, and has out the necessity. of avvaitmgi the completionv of the operation of the one of her controlling equipments used, her telephone being 'automatically connectible to a calling line, together with an alternate. equipment, as soon as it becomes idle.

In the invention another feature provides not only the automatic connection of an operators controlling equipment to a circuit to be extended for the purpose 'of controlling the extension of such circuit to the desired line over automaticselector switches, but also provides for the automatic disconnection of such controlling equipment from lzo such circuit at the very earliest stage in theV connection at which such disconnection can properly take place; That is to say, one of the features of the invention relates to the automatic 'disconnection of the controlling equipment immediately upon the selection in the final -selector switch,y of the set of terminals in correspondence with the numerical I designation of which. the controlling equipment has been operated, such automatic disconnection taking place before the testing of the line associated with such terminals, before the ringing of the lineif such line is idle-and before the response ofl the called subscriber. In accordance with this feature of the invention,the time of use of a controlling lequipment in connection with any selecting operation is materially shortened, the circuits for testing, ringing,'and the establishment of the talking' connection in response to the reply of the called subscriber being purely local, and in no way requiring ling equipment.

-According to the invention, furthermore,

although each connection is established over automatic selector switches, and also preferably over automatic line finder or distributing switches, the operator, to whose position the connecting circuit over which the call has been extended is individual, has at all times access `and complete control over the hconnection established, or being established. For this purpose, the invention provides that each connecting circuit shall appear before the operator in a requisite num- 'l ber of signal lamps and controlling keys,

whereby the operator 'may supervise the conthe assistance, or direction, of the controlnection at any time, and lin any way desirable. n

Another feature of the invention, -and relating particularly to semi-automatic systems, in which supervision of the call established'or being established is always ossible, relates to the -fact that the estab 1shment of the call-that is to say, the receipt of the necessary instructions from the calling party, the bringin about of the necesvisedby another operator.-

Another feature of the invention relating to systems in which lthecall is established over automatic selectorswitches, but havingbeen established is su ervised by an operator at the central o ce, provides that the complete disconnectionl of an established call,- involving the restoration 'to normal condition of all of the apparatus forming part of such connection is controlled by manually operable means #before the super- `vising operator, and in thetparticular form shown herein resides in a single manually operable key individual to the connecting circuit over which such call is established.

It sometimes occurs that it Ais desirable that a connection, being established or fully established should be maintained, While at gie. same time it is desirablethat' the line so onnected should be free to call and be called in the normal manner. A feature of the invention, therefore, relates -to holding the 'switches in the position to whichthey have been brought for inspection or other. purposes, while, at the same time, causing 4the subscribers line, or subscribers lines attached to such connection, to be freed entirely at the line finder or final selector, the brushes of which rest upon the terminals thereof, so that such line or lines m'aycallor be called in the normal manner. As shown the means for accomplishing this holding condition, may comprise relays under the control of manually operated means before the supervising operator, which relays in turn control the apparatus associated with the switches forming the extremes of the connection.

Other features of the invention have to do with the circuits and operation of the line finderswitches by which the idle connecting circuit is brought into connection with a calling line. One of these features provides a pilot relay under the control of any line of a group, whereby' all the idle line finders in which such group of lines terminate will immediately start to searchl fora calling line. The circuit by which the pilot relay is energized also forms one of the features of the invention. This circuit, controlled by a single contact device," provides ,when closed, not only the energizing circuit for the pilot relay itself, but by nzeans of a branch therefrom, places a selectable poten-1 tial upon the test termina-l of the calling line in` all the finder switches in which such line appears, From another standpoint this circuit may be considered as, in part, a coinmon circuit, in whieh'part .the pilot relay common tol a groupV of lines is located, and in part comprising an individual circuit for each of the lines of such group, the estaba line in such a manner that the proper potential will exist upon the test terminal of such line when calling, until suchline has been seized by a line finder switch, at which time thev potential upon such test terminals will be so changed thatno other one of the line finder switches in which such line appears will be able to seize such line, and fur- -thermore, that the potential or changed potential upon the test terminal of one line will have no effect upon the potential, lack of potential or change of potential on the test terminals of another line o f such group, even though the source of potential for such test terminals is in the common portion of such circuit.

Another feature of the invention involves `the vuse in line finder switches, of means whereby immediately upon the brushes of a line finder switch coming` in contact with the terminals of a calling line ai test guard will be placed upon Ythe test terminals of such line, in all other line finder switches in which it appears, to prevent its seizure by any other of such line finders, whereas,

the motion of the seizing line finder will not be arrested until the brushes thereof are properly centered upon the terminals of the line.` This is accomplished by locating` in the test circuit two relays, one of them operating immediately upon the brushes coming in contact with the terminals of the calling line to place the test guard thereon, and the other operating subsequently, upon the opening of a local interrupter device carried by the line finder switch, to arrest the motion of such finder switch. Another feature relates to the subsequent transference of the test relays located in such test circuit-one to an alternative test circuit and the other to a controlling ci'rcuit whereby the restoration of the line finder apparatus to normal may be controlled; as desired. if

Another feature of the invention, relating particularly to systems in which a/calling line is connected to an idle connecting circuit Athrough a plurality of line finder switches, provides tliatfwhen a calling line has been seized, and connected to by a first line finder switch, all of the idle second line finder switches in which appears the cir- Acuit individual to the first line finder switch to which the line is now connected` will startv in motion to hunt, and one of them seize such circuit, whereby the calling line will'be extended to the connecting circuit individual to the` seizing second line finder switch. Related to this feature is another feature of this invention, according to which thecontrol of the starting in motion of such idle second line finders resides in a sequence switch (steering switch) individual to the first line finder, whereby the seizure of the calling line by the first line finder iminedilately initiates the operation of such sequence switch, resulting in the starting in motion of the idle second line finders in which such first line finder is accessible.

Another feature of the invention, and relating particularly to systems in which a ,calling line is connected to an idle connecting circuit by line finder switches is embodied in the provision of line finder switches the brushes of which have no normal position and move in one directionv only. Upon the seizure of a calling line by one of' a plurality of moving line finder switches, all of such switches will, provided no other line is at that time calling, immediately stop in whatever position they may respectively be in, and having stopped, will remain in such position until the establishment in some other line of the group of lines terminating in such switches, of a calling condition, at which time they will again start in motion and continue therein until such line is found.

A related feature of the invention provides that when the brushes of a line finder switch ,rest upon the terminals of a line in which a "calling condition is established, such line finder switch Wlll immediately seize such line Without any movement of its brushes, and prevent the seizure of such line by any other line finder switch.

Another feature of the invention relatingl to systems in which a calling line is connected to an idle connecting circuitl throughv a plurality of line finder switches provides that the restoration of the first finder switch through which a connection has been established is dependent on the condition of the Second finder switch which has formed a of the same connection. It further prov ides that upon the initiation ofthe restoring operationin such connection the apparatus o,

or` becalled inthe normal manner, but the ffapparatus'of such first finder switch will be, Amaintained in an off-'normal pos1tion,to

,prevent the use of such first finder switch in asubsequent connection, until theapparatus offthe second finder switch connected with vit,'and itsconnecting circuit, have been restored to their normal condition.

Other features of the inventionhave to do with the use, location, and operation of s equence'switches (steering switches) 1n various portions of a telephoney exchange system, for controlling various portions of the apparatusand-fthe controlling and extension of the various circuits. Forexample, one ofthe features of the invention'relates to the use of a sequence switch for-controlling the first y, line finder.

Another feature relates to the use of a se- Iquence switch common to and controlling of a plurallty of o A further featurev relates tothe use of the both the second line finder switch and the oup selector. Another feature relates to t e use of a sequence switch .to determine the selection by a calling line of an idle operator rators .to any one of which such calling e may be connected.

same sequence switch for controllingnot only the selection' of an idleoperator but also 'the l selection of an idle controlling-equipment of the operator selected. Still another feature of the .invention rel lates to the use of a plurality of electromech- 40 anisms (herein shown as sequence switches) to accomplish the selection and extension of a'circuit to a. particular one of a plurality of circuits, in such selection the circuit extend-A ingl mechanism (group. sequence switch) understood .that while', for the sake of clear-v switch).

5 l v l u 4 mvention w1ll sullclently appear from vthemaintaini the first said circuit open, but closing. suc circuit when the desired se-V lection has been accomplished bythe circuit choosing mechanism (position sequence Other novel and important features of the detailed description thereof, and it will be ness specific descriptive language must be used in describing the embodiment of the invention shown herein, such langua eis not to' be construed as un any-.way limiting'the invention, since the various features thereof may appear in widely varying and dissimilar forms when used-in other systems than the specific one herein described.

A. system embodying the .invention is diagrammatically illustrated inthe `drawings in whichigure l shows the calling substation and y .the first finder switch will be so operatedthatthe subscribers line to which itis connected will be immediately freed to call 4the controlling .-of Fig. l,

v sidin accompanylinei'and the` circuit of the first line Figs. 2 and '2; show a connecting circuit vand the secondfinder switch and group selector associated therewith.

. Fig. 3 shows the line or final selector and A the substation'circuit o f lthe called line.

A F ig, 4 shows the circuits of two operators" f s uence switches'.`

a whole, F1

he ground `and final selectors areof the multiple brush -type, described in the British Patent N o. 20841/09, in which the brush carriage is driven by constantly supplied power coupled thereto when needed through a magnetic-.clutch andcarries brushes heldfree of the terminals lby latches any one of which may be withdrawn to allow its set of brushes to make contact successively with thesets of terminals individual thereto.

The set of brushes is chosen by a tripping spindle` according to the different angular positions thereof, which is driven by the same -constantly supplied poweras the brush-carriage with which it through a magnetic clutch. i

The line `linder switches shown at and `200 are somewhat similar in-construction to the selectors, the principal differences reset o `brushes mounted on the brush-carriage, and such brushes are normally in position to make'contact with the sets `of contact terminals o ver which they pass. Furthermore, the line lnder switches have no normal position and, having been moved'in hunting acalling line, remain in' such plosition' until subsequently again taken In bothth limanda` swiahes and the selectors the;,top of thet'brush-carriage carries an interrupter which inter-acts with a` toothed rackupon the frame of its switch infsuch a way that'a circuit isv established to maintain the brush-carriagev in motion whenever the brushes are passing from one set of terminals to the next. When the is associated,

in'that they each have but a single brushes are properly centered upon a set of terminals, however, this circuit 1s open and the movement lof the brush-carriage will sto wit a set of contacttermmals.

Thesystem shown also utilizes electro'- l'rnagnetic switchingy devices known as sewith the -brushes squarely in contact l vqhence switches. Devices of this character the British Patent No.

' quence switch in which any of its contacts are indicated by `such contacts, each be vunderstood that the special contact 111" (except the contacts corresponding to 111 of the line finder sequence switch) are closed, numbers placed adjacent to" A contact being open in all positions except those indicated by such reference numerals. For example, contact 58 top is closed in the fourth and from such position through the seventh position of the line finder sequence switch'of which it forms apart as indicated by the Anumbers 4-7 adjacent thereto, and the alternate or bottom Contact is closed in the first and second positions, as indicated `by the gures 1, 2, adjacent to such alternate contact, said contact being open in all positions except those so indicated. In the case of the special contacts such as 111, the numbers-are placed on the opposite side of the switch lever from its Contactpoint and indicate positions in which the 4Contact is opened, such contact being closed continuously while the rotary element offsequence' switch is in transit between positions indicated. It will therefore of the sequence switch105 is closed continuously betwen positions 1' and 4, 4 and 5, 5 and 7, and 7 and 1, but is opened when the sequence switch is either resting in or passing through any one of these positions.

A In the system herein disclosed, the operator receives the number from the subscriber and then manipulates keys which serve to set in operation mechanism adapted to eX- tend the connection automatically to the desired line and these keys are divided into 45.

four setsof ten each for the thousands, hundreds, ltens and units respectively, These keys are shown diagrammatically in'Fig. 6. The operator having received the number of the desired line presses a key of each set corresponding to digits of the number desired. locked down whenV depressed, and remain in such condition until the magnets are denergized.

There are provided at each operators position two duplicate senders. A and B, each controlled by a sequence switch 505, and

each comprising twentv-pairs of counting relays 179, 180 and four registers whose power magnetsare designated 160, 161, 162, and 163, and belongto the thousands, hundreds, tens and units registers respectively.

o In general, lthe register is a sequence switch having the usual power magnet and the usuall contacts operated/by cams, located on revolve their shafts, and wh contacts on the registers corresponding to The keys are electromagnetically the sequence switch shaft. The only difcontacts of which are connected with the thousands keys. It has in addition a spring 191 shown below.

` The hundreds register 161 has in addition to the five springs shown above its power magnet, the coperating contacts of which are connected with the springs of the hundreds keys, five springs numbered 183, 187, and ve springs numbered from 192- 196; also spring 197.

The tens register, has in addition to the tive springs, the contacts'of whichare connected to the tens keys, five springs numbered 1883-1871.

The units register has inLadditio'nfto the five springs, the contacts of which are con nected to the units keys, tive springs numbered 192b-196.

In general it may be stated that when the register power magnets are energized, they n the upper the keys depressed' b'y the operator are reached, 'circuits are closed through the stop relays 17 0-17 3 which cut O'the powerfrom the register and stop it revolvingwith the upper contact closed. in each corresponding to the depressed key. The lower springs of the registers are .closed or open as indicated by the position numbers adjacent thereto according to the set position of the register as determined by the upper springs and such lower springs control the operation of the counting relays .which themselves determine the number of stepsthat the various selectors are to take in their operation to eX- tend the connection to the desired line.

The operator isprovided'1 with the usual telephone set (not shown) which is connected to the conductors leading from the lower contacts of sequence switch springs 90-91 (Fig. 2). The upper contacts of the same vsequence switch springs lead to the telephone set of the operator located to the i left; who may assist the home operator. This operator will be referred to as anv alternate operator. The operators telephone set is also connected to the conductors leading from the springs but these connections are also -`omitted-for the sake of clearness. This key is to permit the operator to communicate with a sub-` scriber after her telephone set has been automatically disconnected in the normal operation of the system. The operator is also of the listeningl key 288,

a duplication o f the means for connecting the left handl operators set.

The subscribers set is of the kind usually provided in common battery manual telephone eXcha'nges. The lines are connected to multipled .terminals in the banks of each of a group of rst line finder switches.

AThey alsov appear in multipled terminalsA of the proper n al selectors. There may be provided a smaller number of line finders than subscribers, and a still smaller number of second line finders (200) may be prvided, and o erate" substantially in the same way-'as the rst `line finder, each second line.

finder being connected with a group `switch Y connected to battery, this finder willstop ro4 associated with the grou It will be understood that'the sequencel switch springs inFig. 2 surrounded by the .dot and dash lines are associated with the position `sequence switch 305, whereas all those outside of the dot and dash linesv are sequence switch 205, which latter contro s the line finder switch and 'group selector.

The system shown is best described by an lexplanation of the yoperation thereof. f

Assume that the subscriber whose sub- -stationis shownat 50on Fig. 1 desires connection with the subscriber, the numerical designation of whose lineis 1149, and fura ther assume that such subscriber is the .one

whose substation is shown at 278 on Fig. 3. When the subscriber at'50 removes the telephone from its hook, the line relay 51 (Fig 1) is energized, and closes a circuit to energize the pilot relay 52. This circuit also, by means of a branch leading oi between the resistance 53 and the resistance 54, placed a selectableA potential on the terminal 104 of the line finder 100, and of all the, other line* finders of the group in which this line appears. This pilot relay 52 is commonto such group of line finders, and when energized, causes the. brush-.carriage'of all ofthe idle finders in the group to rotate, over circuits includingrsprings 55 bottom, and 56 bottom, and brush-carriage power magnet '106. A" group' of idle first -inder switches is now hunting for the calling line,

the brushes traversing the line terminals- 101, 102, 103, 104, and when the firstv arriving line finder is fully centered upon the calling line whose test terminal 104.has.been

tating due to the 'closure' of the circuit through relay 107 which includes spring 58 bottom', upper (highresistance) windingv of squarel 104 by thecalling through two circuits in parallel, each of test relay 108, spring 59 bottom, brush 104B, terminal 104, resistance 53 and relay 52. The resistance of the` shunt circuit from resistance 53 through resistance 54 to ground is so proportioned that sutlicient current will flow through relay 108 to actuate it. Relay 108 is energized before relay 107 due to the shunt about the latter closed by the interrupter 109 whenever the brushes are not centered on the terminals, and in respon ing closes at its front contact apath of low resistance through its lower winding, so reducing the potential of the. test terminal 104 and its multiples that no other relays 108 and 107 can be energized thereby, and therefore causing the line to appearnoncallin to all other line linder switches.l If

two -lme finders should reach the terminal 104 of a calling line at the same time, the circuit from-'the battery placed on terminal line would be closed which would contain relays 108 and 107. The two relays 108 would lconsequently be simultaneously energized and generally-one of the two would close its armature contact first, by virtue of which the circuit containing this relay, due to its decreased resistance, would draw the major part of the currentof the parallel circuit and the second relay 108 would therefore receive insufficient cur rent -to attract its armature. However, if

allel c ircuit would be so reduced that the potential difference at the terminals of the relays -would be so `small that the current traversing the coils of the relays would be insuliicient to hold up the armatures of both relays and one or the other would ydrop back.

When relay 107'is energized, it opens the circuit of the power magnet 106 and closes a circuit to energize' the holding magnet 110 through spring 55 bottom. At the same time relay 107 energizes the sequence switch power magnet 105 over spring 59EL and it moves from position 1 to position 4, ,nfloving through positions 2 and 3 by reason of the closure of contact 111 in those positions. A ts the sequenceswitch moves through position 2 a circuit is closed over sprin 61 and the third brush 103'EL of the Aline fignder to operate the cut-oil; relay 62 which circuit by reducing the potential on the terminal 103, makes the 'seized line test busy in all the final selectors in which it appears. The operation of the cut-oil' relay also connects the line conductors to the terminals 101, 102 of 'the finder at the upper front contacts of relay 6 2,and, unless some other line ofthe group 1s call1ng, and has not as yet been -seized by aline finder, opens the circuit of the pilot rela-y 52 to arrest the'movement of any other line finders which may have been seeking this line. At position 4 of the sequence switch 105a circuit is closed over spring63 to a local wire leading to a group of second line finder switches 2 00, in which the conductorsconneoted to the first line nder switch 100 appear, causing the idle finders of such group to hunt for the first line finder now connected to the calling line.

The sequence switch 105 (Fig. 1.) at position 4 has prepared at'springs 58 top and 57 top a circuit leading to the 4th terminal 204 of this line which will be closed when a second line finder switch "reaches said terminal and will cause, by the energizationgof the relay 208, the inclusion in this circuit of a low resistance pathl to reduce the potenstopped. Potential being present therefore.

- 67, normal contactlof locking key ond line finder over spring 71 bottom and` position 1 into position 2, an impulse is tial of the terminal 204 to render it nonselectable 'to other second line finder switches, and when the brushes have been squarely centered on terminals leading to the calling first line inderswitch the brush-carriage is .upon test terminal 204, upon the test brush 204aarriv1ng thereat, the relay 208'to ground l is immediately energized and a moment later when the ground at the interrupter is removed, the relay207 is also energized'opening the driving circuit of the brush carriage and closing the circuit for the holding magnet. It has also closed over spring 66 bottom and spring 63 (Fig. 1) a circuit for the group sequence switch 205. This sequence switch 205 therefore moves into position 2in which movement an impulse is transmitted to the irst finder sequence switch 105, over left-back Contact of relay 199, spring 69 bottom, and spring 70 bottom.

his sequence-switch is moved into position 5 in which .position the calling subscribers line wires are connected through to the secsping 72 bottom. The circuit of relay 107 of the lirstl finder remains closed at springs 57 and 58 top (Fig. 1) and 65 bottom (Fig.

2) and consequently relays 2 08 and 207 (Fig. 2) and 107 (Fig. 1) remain energized. This is a locking circuit and remains closed until 'the operator` clears out the connection.

As the group sequence switch moves from also transmitted rto the position sequence switch 305 over spring 73 top and spring 74 bottom, causing such sequence switch to move from position 1- into lposition .2, in

which position the test is made for -an idle operator.

In Fig.` 4 are shown two operators sei quence switches, one of which isv associated with the home operatorzs position HP and the other withthe alternate operators posi- 4tion AP, which` alternate operators position only comes into service when the home position HP is busy.

When the operators are on duty the hand 68, relay relay 82 at its front contact switches 75 and 76 at their respective positions are closed. i

When the position sequence switch 305 advanced into position 2, circuits to the position test relays 77 and 78 were closed at spring 79 bottom and spring 80 bottom respectively, to the. home operators position and to the alternate operators position, through the respective hand switches 75 and 76 and the spring 81 top of the sequence switches of such operators positions and over the back contacts of the relays 82 to earth. When, and only when, an operator is idle the spring 81 is closed at the top. -If both the operators should be idle at the moment when the position sequence switch 305 reaches position 2, both the home and the alternaterelays 77 and 78 will be energized These relays establish holding cir- 'cuits from vthe power magnet 305 4over their front contacts, their' right hand windings and the windings of the respective relays 82 to earth. It will be first assumed that the home position HP was idle, and that the alternate position was either engaged or that its hand switch was not closed.

)Vith the group sequence switch 205 in position 2, the position sequence switch 305 in position 2, and the home operators sequence switch 405 in position 1, relay 7 7 will be energized by a circuit over spring 79 bottom, hand switch 75, spring 81 top, and back contact of relay 82, whereupon it closes an energizing circuit for relay 82, i11- cluding .position sequence switch power magnet 305, spring 84 top, front contact of relay 77, right hand winding of relay 77, resistance 83, (Fig. 4) and relay 82. The i closes a circuit by way of spring 85 for the home operators sequence switch, whereupon it moves to po.- sition 2, in which position the resistance 83 is short circuited by the closure'of spring Sti-bottom, with the result that power magnet 305 of the position sequence switch will receive enough current to rotate the sequence switch to position 3. Inasmuch as it was assumed that the relay 77 became energized,

the position sequence switch will move to position 7 since the circuit established remains closed until the position' sequence switch 305 Yhas rotated beyond position 6, when it will be opened at spring 84 top. When this occurs the relay 82 (Fig. 4) is denergized, and a circuit is closed over spring 81 bottom, to energize themagnet 405 which thereupon moves the home position sequence switch into position 3.

With the group sequence switch 205 in position 2, and the position sequence switch 305 -in position 7, the home operators sequence switch 405, as it starts to move from position 2 to position 3, will transmit an v'have'occurredif the alternate o erator hady been idle and her switch 7 6 had een closed,- f the energizing of such relay would have ini.l

205 to move it into position 3. Before the group operators sequence switch fully arrives in position 3 thereof, an energizing.

circuit for relay 82 is closed through magnet 210 of the 2nd nder, front contact of 'relay 207 sprin 64 bottom, spring. 88 bottom, and

spring 87 ottom. This relay 82 is therefore energized-to maintain thehome operators sequence switch in position 3 and remains" energized until the operator has recorded the ca l.

It shouldv be relay 7 8 had been energized simultaneously with the relay 77 in the'second position of the` positionsequence switch, which would tiated a cycle of operations inthe alternate operators sequence switch AP, but since the l position sequence sw'itch, when it moved from its second position, was driven directly the relay 78 is the first to be energized, or ifinto its seventhl position, no holding' or checking circuit would be established or maintained for the alternate operators sel quence switch and it would return immediately to its normal position.` y

On the other hand, assuming that the home operator is busy when the position se- `quence switch arrives in position 2, the relay 77 will not be energized as the circuit for it is `open at contact 81 of the home operators -sequence' switch'.l If at v-this time the alter-A naten'operator .is also b usy, and, consequently, no 'circuit-is establishedv for the relay 78, the

position sequence switchwill remain in p o sition 2 until a circuit for one or the other relays77 or 78 is closed. If the relay 77 is the first one energized the circuit operation will be as .has been described; if, however,

Athe relay 78 was the only one energized when the position sequence switch came into position 2'the position sequence switch in response to the operation of the alternate operators sequence switch, will move into po sition4 3- where the same operation'will --take place-to drive the group sequence switch into position 3 response to the operation of the alternate .operators sequence switch as have been described as taking place in position 7- under the control of thehome operators se- Iquence switch. Also the alternate operators sequence switch will be held in -position 3 in precisely the same manner that the home operators sequence switch' was held inthe same position.

Furthermore,A it will be apparent that if when the position sequence switch comes into position 2 the switches 75 and 76 were both open, the operation of the sequence switches .will be held up just as though both operators were busy and upon the closure of one of such switches, the operation of such sequence switches will forthwith proceed to here observedtha't if thek menace extendtheconnecting' circuit to the operator whose switch is closed. While,however, the

position sequence 'switch stands Vin position 2 the lamp 95 will be continuously lighted indicating to both. the home operator and the alternate operator that acall'is awaiting attention, so thatat all timesall of the opertois hayin access to any given connecting circuit an to which they are automatically connectible as described, will be s .ble to observe just how many calling lines 'are awaitingi attention.

eturning, however, tothe case assumed i' the group sequence switch .205 is now' in .position 3,- the home operators sequence switch 405 is in position A3 and the osition' sequence switch `305 is. in position The `home operators telephone set was connected across the line bythe closure of springs 90 i and 91 vbottom when the position sequence switch 'moved into position 7, Vcurrent for talking purposes being supplied through springs 9 2 and 93 closed in this position.l It

will be noted that lthe calling and supervisory relay 94 is included in vthis circuit` and that these springs areclosed )when the position switch arrives at position 2, thus lighting the lamp 95 in positions 2 and 3 of the second finder` sequence switch for thev purposes described. Furthermore`there is a circuit 'closed through the progress'larnp 96 at spring top, thisV lam remaining lighted until the calledw subscri er has answered;

`that is, during the entire progress of the connection, and is .an indication to` the operator that a callis going. through on this trunk. v p l The operator noting the lighting of the calling lamp inquires the number desired by the subscriber.. In the meantime a selectioncontrolling equipment (Fig. 5) has been selected and seized in the following manner: With they connectingcircuit, therefore,

`connected to the home operator, a test cir" 'cuit is established to pick up the idle one circuit above referred to is continued to re' lay 99, which is energized and establishes a circuit over spring 150 top, for first equipment sequence switch 505 and moves it into' position 2. The circuitV through the relay 99 and the position. sequence switch 305 remains closed., until interrupted atfspring 84 bottom in position9, hence position sequence some earlier period equipment would Lass-,596 l switch 305 assumes position 9, and the relay 99 at the controlling equipment becomes deenergized closing a circuit over spring 150 bottom, to drive the equipment sequence switch (505) into position 3.

As the equipment sequence switch moves from position 2 into position 3, an energizing circuit for the relay 99 is closed by way of spring 151 top (Fig. 5) and spring 152 bottom (Fig. 2). This is a locking circuit for the relay 99 and remains closed until the controlling equipment has established the desired connection, or until the operator at clears out the circuit.

It was assumed that equipment A was idle. If equipment A had been busy and sprin-g 98 top had been closed, the circuit through sequence switch 305 and relay 99 of the B havel been opened immediately at left back contact of relay 99, and hence the position sequence switch 305 would have remained at position 7.

Itshuld be here observed that if the connecting circuit had been in connection with the alternateoperator, that is, with the position .sequence switch in position 3 instead of position 7, a similar testing of the controlling equipments of such alternate operator would have taken place over spring 74 bottom and spring 73 bottom. In that case, if the A equipment had been idle, rthe position .sequence' switch would have been driven to position 5 and such A equipment placed in co'perative relation to the connecting circuit, whereas, if the vA' equipment had been busy, the position sequence switch would have remained in position.V 3 and the B equipment so associated. From this point on the operation is precisely the same whichever operator the connecting circuit is connected with, and whichever equipment of such operator is in controlling relation therewith. In all cases when the designation of the desired .line has been completely recordeid on the operator-s keys Fig. tion .sequence switch will be advanced one position, to lopen the connection to the operators telephone and upon the completion 'of the selection-controlling operation the position sequence switch will be operated (through the group sequencev switch) to move into itsv eleventh position,-all of which will be hereinafter described,.such operation taking place regardless of the position the position .sequence'switch may be iny at that time, that is to say, regardless of which of the various equipments may have been connected with the connecting circuit by such position Ysequence switch to control selection.

The apparatus is now ready for the registration of the designation of thel desired line, and, in accordance therewith, to control the movement of the various switches to connect with the terminals of the required subscribers lin-e. The operator having received the number desired depresses the corresponding keys of the sets of keys shown in Fig. 6.

There is arranged a key -for each digit, there being ten units keys, ten tens keys, ten hundreds keys and ten thousands keys. It may be noted that each row of keys is provided with a holding magnet 290, 291, 292, 293, each arranged to hold depressed the depressed key of its row. The circuit of these magnets is closed -by Way of the spring 294 (Fig. 5) when the equipment sequence switch isin positions 3 to 7, a special releasing key 295 being included in the circuit of the holding magnets to release -the keys if, before the designation of the desired line is completely recorded, the operator should observe that yshe had depressed a wrong key. In depressing `the digit keys, the operator depresses the units key last. When the units key is depressed an energizing circuit'for the equipment sequence-switch 505 is closed to move it into position 6', such circuit 'including the contact on the units key, spring 153 top and spring 154 top. As the sequence switch moves from position 3 ,into position 4, an impulse is transmitted to the group sequence switch 205 over a circuit through spring 1.55"(Fig. 5), spring.

and spring 157 top it "into position 4.,

156 bottoI.ri.(Fig. 2), (Fig. 2) to move As it moves from position 3, an impulse is sent to the position sequence switch 305, over spring 158 top and spring 159, driving it out of the 9th or operators listening position and into position 10. In this position the A equipment of the home position is still connected to' the circuit, but the operators telephone set is disconnected from the circuit at spring bottom and spring 91'bottom, and also the holding circuit 'of the relay 82 of the home operator (Fig. 4) is opened at spring 88 bottom (Fig, 2). The rel-ay '82 of the home operators sequence switch becomes denergized, closing a circuit over spring 81 bottom, to drive the home operators sequence switch to its normal position and render it free to be connected to `other lines to which calling subscribers may be' connected.

4The selection controlling equipment is now ready to control the establishment of the connection.

yAs'the units key of the keyboard was depressed, the same circuit which resulted in the movement of the equipment sequence switch formed a part of circuits established for the various power magnets 160, 161, 162 and 163 of the 10.00s, lOOs, lOs and units registers respectively in parallel by way of spring 153' and the Contact on the units key to earth as above described. These registers rotate until the position corresponding to the depressed key of its -associated set of keys is reached, where the circuits through their power magnets are broken by their respective test relays .170, 171, 172, 173. `For example, if the number four, the fifth, tens key has been depressed the tens register will v be' driven by the energization ofitsv power magnet 162 until it comes into its position 4 when a circuit will be closed through the number four tens key through the register spring, of the upper set of iive springs of such register, adjacent to which the number 4 is placed, and test relay 172. The energization of the test relay by this circuit opens the circuit ofthe power magnet 162 and brings the tens register to a stop in its number four position, whether the other registers are still in motion, vor where they may stop. It should be noted that for the sake of clearness the ten positions of the registers are numbered from zero to nine to agree with the designation of the keys by which they. are controlled. That is to say, when the zero key has been depressed, the corresponding register will move into its zero position, and all of the switch springs of such register designed to be closed in its zero positiomthatA is, all that have the ligure zero placed adjacent thereto, will be closed and remain closed until for the control of a subsequent connection the register is again moved. In this manner, therefore, all of the registers lare simultaneously set to register or record the designation of the ,desired line as recorded by the operator on her setor` keys,

' 'and such keys may then be released to control registration in the B equipment of the same operatorv such release taking place when the equipment sequence switch moves out of its seventh position.

With the group sequence switch 205 in position 4 the position sequence switch 305 in position 10, the equipment sequence' switch 505 in position 6, the fundamental or selecting circuit from the A equipment (Fig. 5) to the group selector 300 (Fig. 2) is ,completed, this selectingv circuit being as follows earth, spring 15S bottom of the group sequence switch, spring 164 bottom of the position sequence switch, back contact of relay 165 (Fig. 5), winding of selecting re.

lay 166, spring'167 of the equipment sequence switch, spring 168 bottom of the position sequence switch, spring 169 bottom of the group sequence switch, line relay 174, spring 175 bottom to battery. Relays 166 of the selection-controlling equipment, and line relay 174 of the group selector are thereupon energized. Relay 174 closes a circuit over spring 176- bottom, which drives the group sequence switch from position 4 into position 5, in which position the fundamental circuit remains unchanged and a circuit is closed over spring 177 top to the power magnet 312 of the brush chooser of independent of,

'sixth level on the group switches.

' vancing stage of the brush choosing mechanism the interrupter 17 S closes a low resistance path to ground which shunts out the selecting-relay 166 (Fig. 5) but maintains energized the line relay 174 of the group selector.

The armature of the selecting relay 166 of the sender circuit therefore falls back and is attracted once for each step taken by the brush choosing'device. Referring to Fig. 5, as the relay 166 is energized, for each closing of its front contact, a relay 179 of the upper counting relays is energized by way of the left back contact'pf the corresponding lower counting relay 180 and spring 181, whereas for each time relay 166 closes its back contact, one of the lower the front contact of the corresponding upper counting relay 179 and spring 182. These counting relays, when once energized, lock themselves over their own right front contacts and springs 181 and 182 respectively, and the circuits for the second and subsequent relays of both the relays 179 and 180 will'be established over such ofthe relays as have been locked up. as will be plainly apparent from yan examination of Fig. 5.

One counting relay after another is energized, first a relay 179,' then a relay 180` then a relay 179, and so on until that pair of counting relays is energized corresponding to the closed register switch springs of the hundreds and thousands registers (as determined by the depressed keys in the keyboard). g,

The selectors used in this systeml are. 200- line selectors so that it is necessary to translate from a decimal system to a system that is non-decimal, corresponding to the grouping of the lines in the switches. The operator, when registering the call, depresses keys vcorresponding to the 1000s, .100s, 10s, and units digits of the desired line, that is, on a decimal basis.

Inasmuch as 200 lines are connected to the final selectors in each group, it follows that each level of terminals in the group selector gives access to a group of 200 lines. The first levelgives access to lines numbered 0-199, the second level 20G-399, the third level 40G-599, andl so on. If it be assumed that the required number is 1149, the trunks leading to the final selectors containing this particular line. are wired to the Consequently, the group selector brush-Chooser must move six steps or stages to selectthe proper set of brushes, which movement will result in the energization and denergization of the stepping relay 166 six times.

In response to the action ot the operator in ldepressing keys in the respective sets to the 1005 register will be 'closed at the top (position 1). The 10s register will have its spring 185a closed at the top (position 4) while the units register will have its springs 183b and 192b each closed at the bottom (pof sition 9).

Y'Vhen the sixth shunting of the stepping relay 166 is caused by the biush-chooser of the group selector, the siXth lower counting relay 180 was energized, and a circuit was closed, over right hand front contact of the sixth counting relay 180, contact spring 196 bottom of `the 100s register, contact spring 191 top of the thousands register, spring 188 bottom of the equipment sequence switch, andlthrough relays 190 and 165. Relay 190 energized closesa circuit to the power magnet 505 over spring 154 bottom, and the equipment sequence switch moves into position 8, in passing through position 7, opening springs 181 and 182, allowing the locked l counting relays to be denergized. As it leaves its seventh position it opened the springs 153 and 294, the spring 294 opening' lthe circuit of the holding magnets 290, 291, 292, and 293, of the several sets of keys and the depressed key in each set resumes its normal position. Spring 153 opens the circuit over which the power magnets '160, 161, 162, and 163, of the registers were put in motion and renders it impossible for the operation of the keys to affect the positions of the registers shown on Fig; 5 so long as 'the' selection-controlling operation is going on. It will thus be seen that though the set of keys may now be associated with the equipment B of the operator by springs performingv precisely the functions of the springs 153 and 294 and, as indicated by the multiple conductorsshown on Fig. 6, so be used to vcontrol the selection-controlling operations of such equipment B in connection with-some other call, no operation of these keysc-an in any Way interfere with the selection-controlling operations now going ou in the equipment A.

With the sender sequence switch in position 8,the selecting circuit is again closed at the controlling equipment for governing selection .according to the 10s digit ofthe wanted line.

When at position 6 'of the equipment `sequence switch, the relay 165 was energized it immediately opened the fundamentalcircuit to the group selector including the line relay 174 (Fig. 2), which relay, when the brush-Chooser has nished its siXth step .or stage and the shunt to earth is opened, will be denergized, opening the power circuit to the brush-Chooser, causing it to stop in its sixth position and also closes a circuit to the group sequence switch 205 over spring 176 top, so that such switch moves into position 6. This is the trunk hunting position for the group selector 300. The third or test brush 303 of the group selector is connected through left hand (high resistance) windingA 0f the test relay 198, spring 69 top, test relay 199, normally closed4 contact of locking `key 68, left hand back Contact of relay 67 to earth. The brushes of the group selector are rotated due to the closure of a circuit from brush-carriage power magnet 306, over spring 250 bottom, and back contact of relay 199. As the test brush 3032L touches a test terminal 303 of a trunk line of an idle iinal selector, upon which terminal there is present the full potential of the battery connected over spring 253, spring 275', relay 2531, and back contact of relay 283, the test relay 198 will be energized, placing' its low resistance right hand winding parallel to its high resistance left hand winding, thereby closing a. low resistance path to the third terminal of the trunk and making it busy by lowering its potential. As soon as the brushes have been accurately centered upon the trunk. the shunt through the interrupter device 286 is removed and relay 199 lis also energized, which opens the circuit of the power magnet 306. and closes the circuit to the holding magnet 310, causing the brushcarriage instantly to stop rotating. The energization of relay 199 also by a circuit over spring 157 bottom' drives the sequence switch 205 into position 7.

In this position the fundamental or lselecting circuit is again closed, this time to the bru-shes 30121, 302% at spring 251 bottom and spring 2 52 bottom, and thence to the final selector 600 by spring 253 bottom to earthon the one hand, and spring 254 top through the line relay 255 to battery on the other. Relay 255 (Fig. 3) and relay 166 (Fig. 5) are t ereupon energized, and the former closes .f n energizing circuit `for the tinal sequence switch 605 over springs 257 top and 256 bottom to move it into position 2, in which position the apparatus is in condition to select the set of brushes in the final selector according to the tens digit of the numbei of the desired line. As the sequence switch moves into position 2 a circuit for vthe brush-choosing power magnet is closed through spring 256 bottom, front contact of relay 255, and spring 258 top. For each step taken by the brush-choosing mechanism the interrupter 259 closes a low resistance path to earth over spring 260 top in shunt ergization of the selecting relay 166 causes it to lock up the counting relays, as has been described infconnection with the selection 4of. the desired llevel in the group selector.

Since wehave assumed that the required number was 1149, the contact 185El top of the s register is closed and the fifth lower counting relay, upon being energized, closes a circuit over its right armature, register spring 185 top of the 10s register, sequence switch spring 188 top, and relays190 and 165. The energization `of the relay 190 by this circuit causes the equipment sequence switch 505 to advance to position 10 and the -energiza-tion of the relay 165 opens the selecting circuit, as explained above. As the equipment sequence switch passes through position 9, it unlocks the counting relays allowin them to assume their normal positions. Vhen the fundamental' circuit is opened atthis timethe relay 255 (Fig.'3) becomes dependent for its energization on the connection to ground through the interrupter 259 and when the brush-Chooser com-4 pletes its fifth step or stage of movement, this connection being open, the relay 255 is denergized and closes a circuit over spring 256 bottom, and spring 261 top,`.for the final sequence switch, moving it into the fifth position. In this position and with the equipment sequence switch in the tenth position the fundamental circuitis complete as before for controllin the iinal selection at the line switch 600. Vhen the equipment sequence switch closes the fundamental circuit at position 10, the final selector line relay 255 (Fig. 3) is again energized, closing a circuit over spring 256 bottom, and spring 262 top for brush-carriage power magnet 606. n

As the brush-carriage passes the tripping spindle `of the brush-Chooser, the selected set of brushes having access to the desired level (containing those havin the tens digit of thewanted line) is trippe and for each set of terminals in this level alow resistance path to ground is closed at the interrupter 263 to the battery side ofthe fundamental circuit over spring 263 top, 'contact springs actuated by arms 263, and spring 260 top. As in the selection of the tens level, the selecting relay 166 (-Fig. 5) is alternately energized and denergized, with the consequent locking up bf the counting relays, the line relay 255 remaining continuously energized. The final selectors are 200-"line machines, having 10 levels of 20 lines each. The first ten sets of terminals of each level correspond to the even hundreds'of 'each group, while the second ten sets of terminals correspond to the odd hundreds of the group. The par- 'l ticular line we are considering is 1149V and since the lowest level is occupied by numbers whose tens 'digit is zeronthe line we are considering lies in the fifth level. The particular units digit of this line appears in .i the lsecond set of ten in this level, inasmuch as its 100s digit is odd. The spring 197 of the 100s register is closed at thetop and will consequently connectinto circuit the units register Springs 192i, 193D, 1941 19511, 19th, keeping open at 197 bottom the circuits of the units'register .springs 183), 1851, 186", 187". Consequently, not until the twentieth counting relay has been energized,will"the circuit be closed over right armature and front contact of the twentieth relay v180, units register spring 1'92b bottom, 100s register. spring 197 top, equipment sequence switch' spring 189 and relays 190 and 165. Relay 165 opens `the fundamental circuit, and causes the re-A lay 255 (Fig.v 3), when the brushes are properlycenteredand the shuntthrough the in- (Fig. 5)l which was started by the energization of the relay 190 moves from position 10 through position 11, an impulse is transmitted to the group .sequence switch 205 over spring 155 (Fig- 5), spring4 156 bottom (Fig. 2), and spring 157 top (Fig. 2). This movesthe group sequence switch into position 8, in which movement-a circuit is closed to' the position sequence switch 305 over spring 158 top and switch spring 159., sending the position sequence switch into position 11.

99 (Fig. 5) at its spring 152 bottom and relay 99 (Fig. 5) becomes denergized, lclosing'a circuit over spring 150 bottom, to drive the equipment sequence switch to its normal positionv and entirely freeing the registering and' controlling equipment A so that it may be used to control selection in settlng up another connection.

It may be notedl that the equipment sequence switch 505 -c oses in position 6 over spring 296 a circuit for the progress lamp297, this lighting of the lamp indicating that 'the first selection, that is, tlie selection in the group selector, `is taking place properly. Similarly in the positions 8 and 10 of the equipment sequence switch, circuits for the progress lamps 299 and 350 are closed over spring 298 top and bottom respectively, these lamps indicating that the tens and final selections areoccurring.

.As the position sequence switch 305 moves into position 11, springs 156, 168, 164, and

The position sequence switch in l position 11 opens the holding circuit to relay

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