US1831399A - Register equipment for automatic telephone exchanges - Google Patents

Description

Nov. 10, 1931. c. E, STEVENS ET AL 1,831,399

REGISTER EQUIPMENT FOR AUTOMATIC TELEPHONE EXCHANGES Filed June 5. 1930 6 Sheets-Sheet 1 DISTRICT SELECTOR I50 I48 I49 l L-lp I Wmvrms C..57'EvE-s M DEN HERTOG ATTORNEY Nov. 10, 1931. c. E. STEVENS ET AL 1,331,399

REGISTER EQUIPMENT FOR AUTOMATIC TELEPHONE EXCHANGES Filed June 5, 1930 6 Sheets-Sheet 2 revs/vs fiypgwu ATTORNEY Nov. 10, 1931. c. E. STEVENS ET AL 1,331,399

REGISTER EQUIPMENT FOR AUTOMATIC TELEPHONE EXCHANGES Filed June 5, 1930 6 Sheets-Sheet 3 a a a C. E 5 TE VENS IN [/5 1V TORS M. DEN Hmroa ATTORNEY Nov. 10, 1931.

c. E. STEVENS ET AL 3 ,399

REGISTER EQUIPMENT FOR AUTOMATIC TELEPHONE EXCHANGES Filed June 5, 1930 6 Sheets-Sheet 4 C. E. STEVENS N VEN 1 4. DEN Hgnroa By M- ATTORNEY Nov. 10, 1931. c, STEVENs ET AL 1,831,399

REGISTER EQUIPMENT FOR AUTOMATIC TELEPHONE EXCHANGES Filed June 5, 1930 6 Sheets-Sheet 5 WVENTO/PS CESTEVENS M 051v HER 7'06 BY Q 6.657140!- ATTORNEY Nov. 10, 1931. c. E. STEVENS ET AL 1,831,399

REGISTER EQUIPMENT FOR AUTOMATIC TELEPHONE EXCHANGES Filed June 5, 1930 6 Sheets-Sheet 6 Ci. STE VENS WVENTWSM. DEN HERTOG A TTORNEY Patented Nov. 10, 1931 UNITED STATES PATENT OFFICE CHARLES E. STEVENS AND MARTINUS DEN HERTOG, OI ANTWERP, BELGIUM, ASSIGN'ORS TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. 'Y., A. CORPORA- TION OF NEW YORK REGISTER EQUIPMENT FOR AUTOMATIC TELEPHONE EXCHANGES Application filed .Tune 5, 1930, SerialNo. 459,381, and in Great Britain June 21, 1929.

. This invention relates to automatic or semi-:

automatic telephone systems and is more particularly concerned with means for establishing calls from'subscribers in an automatic ofiice of one telephone area to subscribers located in telephone oflices of difierent areas such as, for example, from a subscriber in one town to a subscriber in a distant town. The invention provides means for automatically completing calls to oflices of difi'erent exchange areas, each of which areas may comprise a number of telephone offices governed by a numbering system involving a greater number of digits than that of the local exchange area in which the said means are provided. It includes, as well, means for automatically completing calls to ofiices of the local exchange area which likewise may comprise a number of telephone oflices, all of which, however, are reached by one numbering system particular to the local area. More specifically, the invention has to do with means for storing in a main sender some of the digits of a wanted subscriber's number and to store the remaining digits in an auxiliary cooperating sender in such a manner that, upon the dialing of a prefix digit indicating a class of call in which the total number of digits of the wanted number exceeds the registering capacity of the main sender, the said auxiliary sender is connected to the main sender and the remaining digits are then dialed thereinto and recorded. In such cases the auxiliary sender, in cooperation with the main sender and the first selector of the various switching stages, is adapted to control the operations neces sary to transfer the wanted number to the called oifice in'the distant area and there atfect the operation of automatic switches for reaching the wanted subscribers line.

Heretofore, it has been usual to extend long distance calls, when originating in an automatic telephone office, to an operators position and thereupon, under the control of the operator, extend the connection to another operators position located in the office of the distant area and finally, through theautomatic equipment at the distant ofiice to the desired subscribers line under the concally'to the operators position, which number usually consists of two or three digits. Therefore, the total registering capacity of the sender, in so far as it affects long distance calls, has been adapted to the numbering sys-' tem of the home area which may, however, differ from the numbering system of any other area. The present invention, therefore, has for its principal object the provision of registering and controlling means for establishing a complete connection, without the intervention of a toll operator or operators, from an originating subscriber in an automatic office of one telephone area to a wanted subscriber in any one of a number of telephone oflices or other exchange areas each of whose numbering system may be difierent from the numbering system of the home area. In accordance with the invention, therefore, one specific embodiment of which is described herein b way of illustration, this is accomplished 1n the following improved manner: The invention contemplates the use of two senders, a main sender, a group of which is common to a number of selectors of the first switching stage, and an auxiliary sender, a group of which is common to a group of main senders. The main sender contains three principal elements, namely, an in-stepping circuit, a group of registers and an outstepping circuit. The in-stepping circuit is adapted to be connected to 'the calling subscribers line and follows the dial impulses originating at the subscribers substation. The registers are made up of a plurality of sets of counting relays which are adapted to record, on each set, a diiierent digit of the wanted subscribers number and also to control the settings of the various selectors. Each digit, comprising up to ten impulses, is received on a set of these countin relays which set comprises six pairs. To reduce the total number ofrelays required, some of the pairs are released during receipt or delivery of impulses, by means of two additional relays provided with each set of numerical counting relays. The released pair of relays are thus employed twice during the progress of dialing or selection, but when controlling the operation of the selector stages, as more fully described hereinafter, these sets of relays are used in conjunction with a single pair of auxiliary counting relays. Further, on the selection of units digits where, in accordance with the switching mechanism used in the present embodiment of the invention, as many as twenty impulses may be required, two sets of these numerical counting relays are connected inseries and finally to the single auxiliary pair if the number is such that the final selector must be advanced to the second half of the selector bank to reach the called subscribers line. When the number is in the first half of the final connector bank and only the maximum of ten impulses are required, only one set of relays is used, in the same way as for other selections.

The out-stepping circuit is a pulsing circuit arranged in a well known manner which, in cooperation with the counting relay registers, is ,'adapted to control by revertive 1mpulses, the operation of either local or distant selectors in accordance with the number of impulses required for the proper setting of these selectors. The first set of counting relays is used for the registration of two digits, the first and the last digit of the total number of digits registered in the main sender. The operation of a selector stage under the control of a set of counting relay registers proceeds immediately after a digit is dialed thereinto, after which the counting relays are released. By the time the subscriber is ready to dial the second digit to be recorded on the first set of counting relays, these relays will be normal and ready to respond again to dial impulses. Each set of counting relays, therefore, performs the double function of recording the impulses comprising the digit registered thereinto and also of cooperating with the out-stepping circuit to move the various selectors to the particular levels required by the various digits dialed. The relays are used in pairs and count in a known manner; a number of them being operated and locked by the dialing impulses while the complement of the digit, translated for the required level to be reached by the selector as more fully described hereinafter, is used to control the setting of the selectors.

The auxiliary sender is functionally the same as the main sender except that it is adapted to be connected to the main sender only when the latter receives a prefix digit indicating that the total'number of digits to be dialed by the calling subscriber and designating the wanted subscribers line, will exceed the registering capacity of the main sender. A starting circuit, arranged to be closed after such a prefix designation, is operated, whereupon a group of auxiliary senders will proceed to hunt over the finder banks for the calling main sender and, as soon as one of them is connected to the calling main sender, all other auxiliary senders are returned to normal. The main sender, meanwhile, continues to receive the registration of the wanted nuinber up to the limit of its registering capacity and the in-stepping circuit is thereafter transferred from the main to the auxiliary sender so that the registration of the remaining digits will take place in the auxiliary sender. At the same time, the auxiliary sender receives from the main sender additional information as to the total number of digits which is to comprise the wanted subscribers number so that, after the regis tration of the last digit of such a number. a timing switch is operated in the auxiliary sender which delays, for a predetermined interval of time, the further functioning of the auxiliary sender in order to provide an additional period for the dialing of one or two P. B. X. suiiixes. After the expiration of the said time interval, the timing switch closes circuits which cause the auxiliary sender, in cooperation with an impulse switch, the sets of counting relays in the main and auxiliary sender and the outgoing trunk, to transfer to the called office a group of impulses designating the last digit of the Wanted subscribers number; the previous digits having been transferred independent of the timing switch.

The registering means in the auxiliary sender are the same as those of the main sender except that, insofar as the outstepping circuit is concerned, the control and operation of the selectors in the terminating office of the long distance area is controlled by transmitting to those selectors, or receivin equipment controlling those selectors, a num er of alternating current impulses equal to the number required to raise the selectors to the appropriate levels for reaching the wanted line. These impulses are transmitted by the outgoing trunk with which the main and auxiliary senders are adapted to cooperate.

The main sender is arranged to function with a district selector switching stage and is capable of operating with second and third oflice selectors which, for example, are of the kind that provide a loop after trunk hunting is completed, for which the battery and ground must be supplied from the main sender. The final selectors which function from this main sender are of the kind that have a waiting position between tens and units selection positions from which ositions they are advanced by the closure 0 the out-stepping circuit in the main sender.

In the present embodiment of the invention all calls, whether for a wanted subscriber in the home area or for a wanted subscriber in a distant area, ma be-reached over two or more of five switching stages, namely, a district selector, a local second ofiice selector, :1 special service second ofiice selector, a third ofiice selector and a final selector as more fully described hereinafter in the description of the various types of connections. Since the same counting relay registers are used to record the dial impulses as well as to control the operation of the selector switches and since, in general, the number of impulses required to raise the selector switches involved to the required level is a complement of the number of impulses recorded in each counting relay register, the registration of the digit is modified whenever the complement of the digit dialedv does not correspond to the number of impulses required to raise the selector involved to the correct trunk level. It becomes necessary, in such cases,v to translate the dialed digit, that is, to operate artificially certain other pairs of counting relays of the register, or again, to release some which have been operated by the subscribers dial impulses, in'order that the number of normal counting relays corresponds to the number of steps to be taken by the selector to reach the re uired level.

ut going trunk circuits to long distance areas are chosen from any one of ten levels of the special service second office selector banks wherein each level of the office selector corresponds to a different direction or exchange area. This selection is effected under the control of the main sender, the direction be ng indicated by the calling subscriber dialing two preliminary digits which will be referred these fundamental digits, as well as the two direction digits, are recorded on counting relayfregisters in the main sender and all the digits following these four are recorded 1n the auxiliary sender. In addition to the fundamental subscribers number the calling subscriber may dial two suffix digits for the purpose of dialing directly into a P. B. X.'

These sufiix digits are also stored in the auxiliary sender.

Recapitulating the above, it will be observed that the minimum number of digits dialed by the calling party for'a long distance call is six, namely the two direction digits and the four digits of the subscribers number, while the maximum number of digits which may be dialed, is ten, namely two direction digits, a six digit subscribers number and two digit suiiixes for dialing to a P. B. X. Since four of these digits are registered in the main sender the maximum number of digits which can be dialed into theauxiliary sender will, therefore, be six so that six sets of counting relays have been provided in the auxiliary sender for this purpose. The auxiliary sender, in addition to recording the six digits, also takes care that the called partys number is repeated into the receiving equipment in the automatic ofiice of the distant area.

It is assumed, in the present embodiment of the invention, that the called subscribers number for a given distant area always comprises the same number of digits. Depending, therefore, on the second direction digit dialed, the auxiliary sender will have to control the transfer of either four, five or six digits to the selectors of the distant area, which number of digits may eventually be followed by'one or two P. B. X. sufiixes. In case the second direction digit indicates that the fundamental subscribers number comprises but four digits, a particular relay device in the auxiliary sender is made to operate and this relay device will take care that after the four digits which form the fundamental 'subseribers number have been received, a

timing switch is brought into action which, when operated after a certain delay, will prepare to advance the district selector circuit to the talking position and release the registers as soon as the last digit has been transferred to the distant oflice. When one P. B. X. suffix is dialed the timing switch is made 1 to release the instant the fifth digit is received and then starts to act only after the reception of the first P. B. X. suflix. When two P. B. X. suffixes have been received, so that no further digits can be expected, the timing switch is not operated again, but the district selector will be advanced immediately after all of the received digits have been transferred to the distant office.

In a similar manner when the second direction digit indicates that the fundamental subscribers number comprises five digits, .another relay device will operate in the auxiliary sender and bring the timing switch into action for the first time after the fifth digit of the fundamental subscribers number has been received. After this, two sufiix digits may be dialed after which the auxiliary connected to the distant automatic oflice.

' 'cates that the fundamental subscribers num- 5 her comprises six digits, yet another relay device is made to operate in the auxiliary sender and takes care that the timing switch is brought into action aftcrthe reception of the .sixth digit of the fundamental subscribers number after which two sufiix digits may be dialed in the same manner as already indi- It will be seen from the foregoing that the auxiliary sender must transfer the first two digits of the number of the wanted line under control of two counting relay registers in'the main sender. The remaining digits are transferred to the office of the distant area under the control of the counting relay registers in the auxiliary sender.

The scope and purpose of the invention will be more clearly understood by a consideration of the following detailed description taken in connection with the attached drawings in which Fig. 1 shows a district selector;

Figs. 2 and 3 show a main sender;

Figs. 4 and 5 show an auxiliary sender;

Fig. 6 shows a second office selector and a third office selector connected with an outgoing trunk to a distant ofice of a long distance area; Fig. 7 shows the manner in which-the various figures are to be arranged with reference to each other for a complete disclosure of the present embodiment of the invention.

In the disclosure of the main sender as shown in Figs. 2 and 3, two sequence switches of the well known type are used, one of which is designated as switch 236 and the other as switch 357. Section lines A.B and CD run vertically through the center of each figure respectively in order to separate the cams belonging to each of these two switches. The cams mentioned in this description which are located to the left of the above named division lines belong to switch 236, while those to the right of the division lines belong to switch 357.

Connection of a calling subscriliers line with an idle main sender When a subscriber initiates a call by removing his receiver, the calling line is extended in the well-known manner over a firstline finder, to the contact banks of a second line finder switch 2LF, shown on the lefthand side of Fig. 1. A circuit is then closed from battery in the first line finder, conducfor 157, upper contacts of cam 120, left wind ing of relay 128, lower contacts of cam 118, left winding of relay 129 to ground. A circuit, in parallel with relays 128 and 129, is also closed for relay 130 from battery on the upper contacts of cam 120, winding of relay 130, right lower contact and cam 107, cam 108 and right lower contact thereof, back contacts of relay 131, lower contacts of cam 113 to ground. Relay 128 o erates, locks over its left winding and left ront contacts, short-circuits relay 129 and prepares, at its right outer front contacts, a circuit to operate sequence switch ma et 101 from ground on the left back contacts of relay 130, upper contacts of cam 112, right outer front contacts of relay 128 to the winding of switch magnet 101. Since, however, relay 130 is operated, switch magnet 101 is not operated at this time. Relay 130 closes, at its left front contacts, a circuit for the power magnet 132 of the second line finder 2LF from ground on its left front contacts, left upper and lower contacts of cam 104, winding of power magnet 132 to battery. Magnet 132 now operates and drives the brushes of the line finder 2LF which are connected to conductors 140, 154, 155 and 156, over the associated contact bank in search of the. calling line.

As soon as terminal 141, connected with the calling line and marked by a battery potential, is reached by the brush connected to conductor 140, relay 131 operates in the following circuit: Battery through the connecting circuit of the first line finder connected to terminal 141, conductor 140 and associated brush, upper contacts of cam 121, left winding of relay 131, right upper and lower contacts of cam 113 to ground. Relay 131 on operating opens, at its back contacts the aforementioned circuit of relay 130 which now releases, thereby opening the circuit of power magnet 132 at its left front contacts and causing the brushes of the line finder to come to rest on the terminals connected with the calling line. The left back contacts of relay 130 now close the circuit of sequence switch magnet 101 which was prepared at the right outer front contacts of relay 130 as described above. Sequence switch 101 moves out of position 1 to position 3. In passing out of position 1 relay 128 releases by the opening of its circuit at the left upper contacts of earn 120. After position 2 has been passed, relay 131 releases because its circuit is opened at the right uppercontact of cam 121 and, in

position 2 a circuit is closed for relay 133 from ground at the back contacts of relay 134, left upper and right lower contacts of cam 114, right back contacts of relay 128, back contacts of relay 131, right lower contact of cam 108, cam 106 and the right lower contact thereof, winding of relay 133 to battery. Relay 133, on operating, closes an obvious circuit for relay 135. Relay 135, in turn, closes the circuit of the sender selector magnet 136 from the aforementioned ground on relay 134 over the path described for operating relay 133. Simultaneously with the closure of the circuit for relay 133, another circuit is closed from the same ground on the contacts of relay 134, upper contacts of cam 114, left outer contacts of relay 128, winding of relay 153, conductor 154 and associated brush, to a battery circuit extending back into the first line finder. Relay 153 operates and extends the calling line conductors to the district selector.

The sender selector switch meanwhile has started to hunt for an idle main sender (Figs.

2 and 3) the idle condition of which is characterized by a battery test potential on terminal 137. This test potential of an idle main sender is provided from battery through winding of relay 369, left inner back contacts of relay 348, right upper and left lower contacts of cam 302, resistance 304, conductor 374, conductor 137 and associated terminal. A parallel circuit is also closed from battery through resistance 375 to the right lower contact of cam 302 in position 1. When an idle main sender is found, relay 131 operates again over a circuit having battery on conductor 137 and associated terminal, conductor 158 and associated brush, left upper and right lower contacts of cam 110, left winding of relay 131, left contacts of relay 133, to ground at the left inner back contacts of relay 128. Relay 131, on operating, opens the aforetraced circuit of the sender selector magnet 136 which therefore stops. Relay 133 releases also and, in turn, releases relay 135 which, at its right contacts, closes a circuit for sequence switch magnet 101 from ground at the left back contacts of relay 130, right contacts of relay 135, lower contact of cam 103, cam 102, winding of magnet 101, battery. Sequence switch 101 therefore moves to position 4. The calling subscribers loop is now extended over the upper contacts of cam 118 and the left upper and lower contacts of cam 119, brushes 138 and 139 of the sender selector into the main sender by way of conductor 267, middle winding 800 of tone coil winding of relay 200, battery, and conductor 268. right outer winding 801 of tone coil, winding of coil 206 to ground. Relay 200 operates over this circuit. Also, as soon as the district selector circuit reaches position 4, the following circuit from the main sender is closed to operate relay 159 of the district selector: ground on cam 274, cam 255 and left lower contact thereof, resistance 285, conductor 397 and associated terminal, conductor 151 and associated brush, right lower and left upper contacts of cam 117, winding of relay 159, battery. Relay 159 operates in this circuit and prevents the district selector sequence from moving beyond position 4 by opening the circuit for relay 130 at its back contacts.

Relay 369 operates in series with relay 131 over the testing circuit above traced and, in closing its front contacts, closes a circuit for relay 201 which may be traced as follows: ground on the middle inner front cont-acts of relay 369, conductor 372, resistance 202,

left lower and right upper contacts of cam 246, right lower and upper contacts of cam 247, winding of relay 201, resistance 204, battery. Relay 203, with its low series resistance 205, is connected in parallel with relay 201 in this circuit so that the quantity of current which is passing through relay 201 rises to its full value slowly so that relay 201, after some delay, will close a ground on its front contacts to the left contact of own 238, cam 237, to sequence switch magnet 236 and thereby move sequence switch 236 out of position 1. Relay 203 also operates in the aforetraced circuit. After position 1 has been passed, the circuit in which relay 369 was operated is opened at the left lower contact of cam 302 but relay 369 is held locked in series with resistance 304 over the following circuit: battery and winding of relay 369, left Inner contacts of relay 348, outer front contacts of relay 369, lower contacts of cam 303, resistance 304, conductor 374, conductor 137 and associated contact, conductor 158 and associated brush through the right contacts of earn 160 to ground. At the same time resistance 375 to battery is connected in parallel to the above circuit through the right lower and upper contacts of cam 302 and the test potential resulting from the winding of relay 369 being in parallel with resistance 375 is maintained on conductor 137 until switch 236 has advanced beyond position 2%.

Relays 201 and 203 remain operated, therefore, in the circuit from the front contacts of relay 369 until the left lower contact of cam 246 opens after position 1 Before this happens, however, a circuit has been closed from ground on the front contacts of relay 201 over the left lower and upper contacts of cam 247 to the winding of relay 201 so that this relay gets saturated during the time that the left lower and right upper contacts of cam 247 are closed simultaneously and will, therefore, release slowly after this circuit is opened. At the same time the ground on the front contacts of relay 201 is connected through the lower contacts of cam 247 di rectly to the winding of relay 203 so that this relay is maintained operated with full current flowing through its winding until relay 201 releases. When relay 201 releases, relay 203 will also release slowly and then provide a circuitforthe sequence switch 236 to advance it out of position 2 from ground on the back contacts of this relay are connected via the left upper contact of cam 245 to the sets of counting relays. In case, however,

that relay 200 should be energized before the sequence switch has succeeded in passing through position 2 it will provide a circuit on its front contacts to the upper contact of lease only if the subscriber should make apremature release and thereby cause a very long break of the front contacts of relay 200. Sequence switch 236 is now advanced to position 5 by a ground at the right lower contact of cam 240, over the aforetraced path to cam 237.

In position 5, the primary winding 802 of the dial tone coil is excited over the upper contacts of cam 244 to tone source DT. The tone is repeated into the secondar 800 and tertiary 801 windings thereof an the subscriber receives the dialing tone in the well known manner.

In order to avoid confusion the reception of impulses will be described generally at first while the translation and modification thereof in connection with each type of call which the main sender is to handle will be considered under separate headings. It should be understood however, that the reception of impulses into the various sets of counting relays and their delivery for setting the various selectors actually takes place simultaneously.

The first digit is dialed in positions 5 and 6 of switch 236. A number of interruptions in the line, according to the digit dialed, causes relay 200 to release and 'to make its back contacts an equivalent number of times. When relay 200 makes its back contacts for the first time, it closes a circuit for relay 201 from ound on its back contacts, left upper and right lower contacts of cam 245, back contacts of relay 207 to the winding of relay 201. Relay 201 operates and closes an aforetraced circuit to magnet 236 thereby advancing sequence switch 236 from position 5 to position 6. Relay 201 will remain operated until the last impulse of the first di 't 1s over and then closes an obvious circuit or switch 236 in position 6, which then advances to position 8, the switch being carried through position 7 by the grounded left upper contact of cam 237 in the well known manner. When relay 200 makes its back contacts for the first time, a circuit is also closed for the first counting relay 214 in parallel with relay 201. This circuit is traced as follows: Ground on back contacts of relay 200, left upper and right lower contacts of cam 245, back contacts of relay 207, upper contact and cam 247, cam

250 and left upper contact thereof, conductor 270, right back contacts of countin relay 219, left normally made contacts of reIay 221, conductor 269, right back contacts of relay 215, winding of relay 214 to battery. Relay 214 operates and closes, on its left contacts, a holding circuit in series with relay 215. Relay 215, however, is kept short-circuited over its right back contacts and winding by the ground on the back contacts of rela 200 over the aforetraced pulsing circuit an also by ground supplied from the right lower contact of cam 251, left upper contact of cam 251, conductor 376, upper contacts of cam 359, conductor 377, right back contacts of relay 221, left contacts of relay 214 to the winding of relay 215. This short circuit is maintained until relay 200 reoperates after which relay 215 will operate, locking in series with relay 214 to ground on cam 251 over the aforetraced path and also advancing the ulsing conductor 269 connected with the ack contacts of relay 200, to the next counting relay 212. In the same way, every interruption of the dial causes a pair of counting relays to operate. The fifth interruption causes relay 218 to operate overa circuit from ground on back contacts of relay 200 over the aforetraced circuit to conductor 269, the right front contacts on relays 215, 213, 211 and 209 in series, left inner back contacts of relay 220, winding of relay 218 to battery. When relay 218 operates, it operates relay 221 by closing ground on its left contacts. Relay 221, over its right front contacts, closes the aforetraced ground from cam 251 on conductor 377 to the winding of relay 220 and operates relay 220. The right back contacts of relay 221 open the holdmg circuit of all the counting relays locked up, other than that of relay 218 which holds from the ground on the back contacts of relay 200 now extended to the winding of relay 218 over the left front contacts of relay 221. During the period when relay 200 is on its back contacts for the fifth impulse and relay 218 is operating in consequence, relay 219 is held short-circuited by ground from cam 251 aforetraced to conductor 377 directly to one side of the winding of the said relay and by the ground from the back contacts of-relay 200 through the left front contacts of relay 221, front contacts of relay 218 to the other side of the winding of the said relay. Consequently, when relay 220 operates, the short circuit around relay 219 is removed and this relay then operates in series with relay 218 from battery on the winding of relay 218, winding of both relays in series thru the right contacts of relay 218 to ground on cam 251 through conductor 377. Relays 218 and 219 are now locked over this circuit. By the operation of relay 219, the pulsing conductor 270 is transferred from conductor 269 to conductor 271 and the next impulse is directed to relay 216 and its holding ground is directly connected to conductor 377. The holding ground for the other counting relays is also to conductor 377 but this time through the left front contacts of relay 219. The counting operation then proceeds until all the impulses of the digit have been digit determines the character of the call that is in progress. Every kind of call may require a different translation depending on the relationship between trunk levels and available normal counting relays and this will be described in connection with the selections for the different classes of calls above enumerated. Postponing to a later part of this description the particular character of any call, we will describe, at the present time, the successive registration of a number in the main sender with respect to the manner in which successive digits are recorded on the various sets of counting relays.

In position 8 of switch 236, the back contact of the instepping relay 200, is connected to relay 201 and to the second set of counting relays through the following path: ground and back contacts of relay 200, left upper and right lower contacts of cam 245, back contacts of relay 207, upper contact and cam 247 cam 250 and right upper contact thereof, left outer back contacts of relay 230, conductor 384 to the right back contacts of counting relay 315. When the second digit is dialed, a certain number of the second set of counting relays are made to operate in the same manner as described for the first digit. At the same time relay 201 operates in the aforementioned circuit, advancing sequence switch 236 to position 9 and when the second digit has been dialed, relay 201 releases again and advance sequence switch 236 to position 10 over the circuit previously described.

The third digit is received in position 10 and 11 of switch 236 on the third set ofcounting relays 318331 and in a similar way to that described for the first digit. The circuit from the back contacts of relay 200 may be traced as follows: ground and back contacts of relay 200, left upper and right lower contacts of earn 245, back contacts of relay 207, upper contact and cam 247, cam 250 and left lower contact thereof, right inner back contacts of relay 228, conductor 382, to right back contacts of counting relay 329.

The fourth di it is received in positions 12 and 13 of switdla 236 on the fourth set of counting relays 332-346 in the following circuit: ground and back contacts of relay 200, left upper and right lower contacts of cam 245, back contacts of relay 207, upper contact and cam 247, cam 250 and right lower contact thereof, left back contacts of rela 228, conductor 383, to the left back contacts of counting relay 344.

The fifth digit is received in positions 14 and 15 of switch 236 on the first set of countin g relays 208221. As explained more fully hereinafter, by the time that the subscriber is ready to dial the fifth digit, the first set of counting relays will have already functioned to make selections controlled by the first digit recorded therein and will have released so that these relays are again available for registration and the fifth digit is recorded therein and the corresponding selection controlled by them. The circuit from the back contacts of relay 200 may be traced as follows: ground and back contacts of relay 200, left upper and right lower contacts of cam 245, back contacts of relay 207, upper contact and cam 247 cam 250 and left upper contacts thereof to the right back contacts of relay 219. At the end of the fifth digit, relay 201 releases and thereby advances sequence switch 236 to position 16 where it will wait until the selection has been completed or until the subscriber releases.

Translation and selection The translation and selection will now be described for certain kinds of calls which the main and auxiliary senders are designed to handle.

Long distance call A long distance call is characterized by the first digit dialed being zero, so that, when the subscriber has finished dialing the first digit, all the counting relays of the first set 208221 are looked as well as the locally held relays 220 and 221. A path is now closed for relay 347 from ground at the front contacts of relay 220, left front contacts of relay 209 and left upper and lower contacts of cam 233 conductor 803, conductor 378, winding of relay 347 to battery. Relay 347 operates and looks over the following circuit: ground and cam 251, cam 242 and left upper contact thereof, conductor 380, left outer front contacts of relay 347, conductor 803, conductor 378 to winding of relay 347. This locking ground is also extended to conductor 381 by I of calls, a long distance call requires, in the present embodiment of the invention, three settings in the originating ollice, namely, one on the district selector, another on the special service second oflice selector and still another on the third oiiice selector. The reason for this is the fact that the trunks towards the various distant areas are taken off the banks of the third ofiice selector which are reached, in the present example, over level 10 of the district selector and level 3 of the special service second ofiice selectors. This means that the main sender must be able to control three selections before any digit of the distant subscribers number is sent out to the distant office. The first two digits which are dialed and which indicate the direction of the call must, therefore, control relays 318-331. Likewise, provision is made to register the third digit on the fourth set of counting relays 332346 and the fourth digit on the first of counting relays 208-221. Relays 208-221, as already explained are used twice so that by the time the subscriber is ready to dial the fourth digit of the long distance call, that is, the second digit of the Wanted subscriber number, it will be regis tered on relays 2()8221. Consequently, the

- operation of relays 228 and 230 take care that the back contacts of the instepping relay 200 for the second digit, is changed over from the second to the third set of counting relays 318-331. The various paths involved for the pulsing ground on the contacts of relay 200 are as follows: Second digit; ground and back contacts of relay 200, left upper and right lower contacts of cam 245, back contacts of relay 207, right upper contact and cam 247, cam 250 and right upper contact thereof, right outer front contacts of relay 230, conductor 382 to the right back contacts of counting relay 329 of the third set of counting relays. Third digit; ground and back contacts of relay 200, left upper and right lower contacts of cam 245, back contacts of relay 207, right uppercontact and cam 247, cam

250 and left lower contact thereof, left frontcontacts of relay 228, conductor 383 to the right back contacts of relay 344 of the fourth set of counting relays. Fourth digit; ground and left back contacts of relay 200, left upper and right lower contacts of cam 245, back contacts of relay 207, right upper contact and cam 247, cam 250 and right lower contact thereof, right middle front contacts of relay 228 to the right back contacts of relay 219 of the first set of counting relays.

When relay 355 operates after the dialing of the first digit, it places a battery over two parallel resistances 369 and 370 over the two back contacts of relay 354 on conductor 393 associated with the test terminal in the auxiliary sender connecting iindcr banks. At the same time the starting circuit for these finders is energized over another resistance 385. Relay 526 energizes in series with resistance 385 over conductor 588 and operates the starting relays 525 which close the circuit for the power magnets 543 of all free auxiliary senders. As soon as one finder arrives on the test terminal of the calling main sender, relay 527' operates from ground on its left winding, lower contacts of cam 551, test conductor 56? and connecting brush, conductor 392 and associated terminal, left outer back contacts of'relay 354, parallel resistances 369 and 370 to battery. The operation of relays 527 breaks the circuit of the finder magnet 543 at its back contacts and stops-the finder switch. When relay 527 makes its front contacts, a circuit is closed through its right low resistance winding in series with the wind ing of relay 529. This circuit is again in parallel with the left winding of relay 527, conductor 567 and associated connecting brush. This reduces the effective resistance to the test terminal and makes it test busy for all other finders, and, due to the resence of the low resistance potential, re ays 527 of other auxiliary senders will not 0 erate on testing the terminal and will there y cause the finders to pass by the main sender which is now connected with an auxiliary sender. Relay 529 operates in the above circuit and, in turn, closes a circuit for relay 530 from ground 011 contacts of relay 529, right lower and left upper contacts of cam 550, winding of relay 530, resistance 563 to battery. Relay 530, on operating, operates relay 454 over a circuit from ground on its left inner front contacts, conductor 568 to the winding of relay 454 which connects the remaining brushes of the auxiliary sender finder through to the main sender circuit. To start the auxiliary sender, sequence switch 544 is advanced from position 1 to position 2 over a circuit from ground on the right outer front contacts of relay 530, left upper contact and cam 549, cam 548, winding of magnet 544. The holding brush associated with conductor 569 is connected through the left outer front contacts of relay 530 over the left upper and right lower contacts of cam 551 in parallel with test conductor 567 so that the auxiliary sender after position 2 is held over the circuit associated with conductor 569. Relay 530 also connects a ground from its right inner front contacts to the left lower contact of cam 556. Since cams 555, 556, 558 and 468 are connected together, this ground is extended to these cams also.

While these operations have been taking lace, the subscriber has been. dialing the ong distance number, recording the first four digits of that number on the various sets of counting relays of the main sender to position 14 and relay 207 is operated over the following circuit: ground on earn 251 and left lower contact thereof, left outer front contacts of relay 222, winding of relay 207 to battery. Relay 207, on operating, transfers the ill-dialing pulsing conductor over its left frontcontacts directly to a conductor which is now connected to its associated terminal 011 the auxiliary finder bank with brush and associated conductor 471 of the connected auxiliary sender. Since the operations for connecting an auxiliary sender to the main sender were started after the reception of the first digit indicating a long distance call, an auxiliary sender is waiting and ready to receive dial impulses when the subscriber is ready to dial the fifth digit. Vhen, therefore, relays 530 and 454 are operated, the circuit is ready to receive the various digits that the calling subscriber will dial into the auxiliary sender, since the in-di'aling circuit from the back contacts of relay 200 in the mainsender isnow connected to the auxiliary senderover the following circuit: ground and back contacts of relay 200, left upper and right lower contacts of cam 245, left front contacts of relay 207, brush of connecting finder and associated conductor 471, left outer front contacts of relay 454, conductor 475 through the chain of outer right back contacts of relays 453, 452, 451, 450, 449 and 448 to the right back contacts of counting relay 411.

Before describing the operations which take place in the auxiliary sender, we will describe the various selections which take place as a result of the subscriber having dialed four of the digits into the main sender understanding however, that the operations of dialing and selecting take place simultaneously. After the first digit is dialed, sequence switch 357 is started from position 1 over the following circuit by sequence switch 236 arriving in position 8: ground on cam 251, conductor 373, cam 301 and right lower contact thereof, left lower contact and cam 363, cam 365, winding of magnet 357. Switch 357 stops in' position 2% which is the first selection position for long distance calls and this selection is made under the control of the first set ing ground for the first set of counting re-' lays is furnished over two paths in position 2% of switch 357, the first by way of conductor 377, upper contacts of cam 359 to' ground on cam 251 as already described, and

the second over conductor 376, conductor 386, left outer back contacts of relay 347, conductor 380, upper left contact and cam 242 to ground on cam 251. After the first digit is dialed and position 6 has been passed by sequence switch 236, the first holdin circuit is opened at the upper left contact 0 cam 251. However, due to the fact that zero has been dialed and rela 347 operated in consequence, the second hol ing path is also opened at its left back contact. All of the counting 'relays 208-221 will, therefore, release and thereby make it possible for the selector whose operation is controlledby these relays to take ten steps. However, there is another pairof counting relays, used in common with all others, which also requires a pulse for their operation. This pair of relays is relay 223 and 224 and will be used, as described hereinafter, to cooperate with the first set of counting relays in the selection operation. Since all the counting relays of the first set are normal and counting relays 223 and 224 are used also, the selector would take eleven steps to satisfy the counting relay register.

It becomes necessary, therefore, that in arranging for the selection of the tenth level at the district selector bank one pair of counting relays will have to be operated artificialy ly before selections begin. When, therefore, switch 357 advances from position 1 to position 2 4 and passes position 1% a passing circuit is closed from ground on the lower right contact of cam 274, both left contacts of cam 274, right outer front contacts of relay 222,

, right back contacts of relay217 to counting relay 216.. When the switch leaves position 1 ground is removed and counting relay 217 operates in series with relay 216 and both relays lock to ground on cam 251 over the holding circuit already described. The selection of the tenth level of the district selector bank will take place with relays 216 and 217 operated, thus insuring, as described below, the taking of ten steps by the district selector.

When sequence switch 357 arrives in position 2%, the main sender is ready to control the operations of the district selector to select the tenth level and the out stepping or fundamental circuit is closed. This circuit is as follows: battery on the left lower and right upper contacts of cam 120, winding of relay 130, right lower contact and cam 107, cam 106 and right upper contact thereof, conductor 142 and associated brush, conductor 143 and associated terminal, left outer back contacts of relay 226, right back contacts of relay 224, winding of relay 225, resistance 272, left lower contact and cam 256, cam 274 to ground. The front contact of the out-stepping relay 225 is now connected to the first set of counting relays in the following circuit: front contacts of relay 225, left upper and lower contacts of cam 241, left and right and connects, at each step, a temporary ground from the spindle interrupter 141 to the fundamental circuit. This ground maintains relay 130 operated and, at the same time, short circuits the out stepping relay 225 by passing the spindle interrupter ground 141 to conductors 142 and 143 by way of cam 107 and left lower contact thereof and right front contacts of relay 130 so that relay 225 will release for every step taken by the trip spindle. It will be seen that the counting relays will now work under similar conditions when out stepping as they did when receiving the impulses from the in stepping relay 200. Since the first digit dialed is zero and all the counting relays are released except relays 216 and 217, as already described, the counting operation begins with relay 214 as in in dialing. The fifth impulse is absorbed by relays 218 and 219 but relays 216 and 217 do not release with the operation of relays 220 and 221 but are locked to holding ground on earn 251 through conductor 377 as previously described. On the tenth impulse. the ground from the out stepping relay 225 is connected to the winding of relay 223 by way of the right front contacts of relay 209, left inner front contacts of relay 220, left upper and lower contacts of cam 266, left back contacts of relay 224 to the winding of relay 223. On the tenth impulse relay 223 operates. Relay 224 is maintained short circuited by ground on cam 274 through cam 256 and left upper contact thereof through the left front contacts of relay 223. When relay 225 releases, this short circuit is removed and relay 224 operates in series with relay 223 to ground on cam 274.

The fundamental circuit is now opened at the right back contacts of relay 224, relay 130 releases and the trip spindle 140 stops. The front contacts of relay 224 start sequence switch 357 from position 2% by closing ground on the left middle back contacts of relay 226, front contacts of relay 224, contion 2%.

Meanwhile the district selector, with the release of relay 130, advances the sequence switch 101 to position 8- by way of ground on the left back contacts of relay 130, right back contacts of. relay 135, lower contact and cam 103, cam 102, to the winding of magnet 101. The district selector then advances to the hunting position for the selection of an idle trunk on the tenth level and eventually to the selection beyond position in the known manner; the hunting of the district selector for an idle trunk not taking place under the control of the sender.

The sequence switch 357 stops in position 3% until the sequence switch 236 arrives in position 9 indicating that the second or thousands digit has been received.

When the second digit is dialed, switch 236 is advanced to position 10 by the release of relay 201 at the end of the digit over a circuit previously described. 'Switch 357 is advanced from position 2% to position 5 by ground on cam 251, conductor 373, cam 301 and left upper contact thereof, right upper contact of cam 363, cam 365 to winding of switch magnet 357. Second digit selections can now be made, the fundamental circuit being closed once more'andthe, third level of the special service second ofiice selector bank is selected. The second selection is controlled by .the second set of counting relays of which none are energized by any digit received since, as already noted, the second digit is directed into the third set of counting relays. The third level of the special service second oflice selector must be selected and, in order to do this, conductor 387 from the front contact of' counting relay 312 is disconnected from the armature of counting relay 311 at the leftback contacts of relay 222 and is now connected via the left front contacts of relay 222 and the upper right and left contacts of cam 254 directly to relays 223 and 224. This means that after two pairs of counting relays have been energized the front contact of relay 225 is connected to relays 223' and 224 for the third impulse so that the fundamental circuit is opened after the third step of the trip spindle of the special service second office selector. The fundamental circuit path is as follows: battery through the winding of a relay in the special service second ofiice selector similar to relay 130, conductor and terminal 144, brush and associated conductor 145, right upper and lower contacts of cam 105, conductor 142 and associated brush, conductor 143 and associated terminal, left outer back contacts of relay 226, right outer back contacts of relay 224, winding of relay 225, left inner back contacts of relay 229, upper contacts of cam 257, right back contacts of relay 226, conductor 146 and associated terminal, conductor 147 and associated brush, right lower and upper contacts of cam 150, conductor 148 and associated brush, conductor 149 and associated terminal to ground in the special service second oflice selector. The front contact of the step ing relay 225 is now connected to the second set of counting relays 304-317 over the following path: ground on contacts of relay 225, upper contacts of'cam 241, left lower and upper contacts of cam 258, conductor 275, left outer back contacts of relay 349, conductor 388, right outer back contacts of relay 232, conductor 384, to the right back contacts of counting relay 315. The fundamental circuit now functions and during the operation of the special service oflice selector counting relays 313, 307, 312 and 306 are oaerated. On the third impulsethe ground rom relay 225 is directed over the front contacts of relay 312, over a circuit previously traced to the winding of relay 223 operating this relay. \Vhen the impulse is terminated, relay 224 operates as already described in connection with the descriptionof the first digit and the circuit from ground on the left back contacts of relay 226 to cam 364, previously described, is now closed to advance sequence switch 357 to position 6%. .The counting relays are unlocked when switch 357 passes position 5 by the opening of the locking ground at the right upper contact of cam 360. The special service office selector now trunk hunts for an idle third 'ofiice selector and when one is found and seized, a metallic loop is rovided causing relay 227 to operate in the ollowing circuit: ground and winding of relay 227, right lower and upper contacts of cam 257, right outer back contacts of relay 226, conductor 146 and associated terminal, right lower and upper contacts of cam 150, conductor 148 and associated brush, conductor 149 and associated terminal and brush, conductor 625 and associated terminal, loop within the special service second office selector circuit to conductor 620 and associated terminal, conductor 144 and associated brush and terminal, conductor and associated brush, right upper and lower contacts of cam 105, conductor 142 and associated brush, conductor 143 and associated terminal, left back contact of relay 226, right back contacts of relay 224, left lower and upper contacts of cam 259, resistance 294 to battery. Relay 227 operates in this circuit and closes ground on its contacts to conductor 279, upper contacts of cam 367 to the winding of relay 356. Relay 356 operates, locks over its right front contacts to the same operating ground and, at its left front contacts, closes a circuit to the winding of magnet 357 from ground on cam 274, conductor 289, cam 358 and left lower contact thereof, left front contacts of relay 356 to the winding of magnet 357. The operation of the magnet now advances switch 357 to position 7%. Relay 356 is released and another circuit to magnet 357 is now closed in position 7% from ground on cam 251,

conductor 373, cam 301 and-left lower 'contactthereof, left front contacts of relay 354, lower contacts of cam368, left back contacts of relay 356 to the winding of magnetl357. Switch 357 advances to position 10 The selections at the third ofl'ice selector take place under the control of the third set of counting relays 318331 on which, it will be recalled, the second digit is recorded.

contacts of relay 348, upper contacts of cam 302, front contacts of relay 389, which is a relay operated from the front contacts of relay 318, to ground on the left front contact of relay 371, which is a relay operated from the front contacts of relay 322. Relay 369 lock s over its outer front contact to ground on the right upper contacts of cam 303. The holding ground for the third set of counting relays is controlled directly from the left lower contact of cam 359 from position 1 to 7% and 8% to 10 A and over the back contacts of relay 369 and right lower contact of cam359 in position 7 to 8% and thence back to the left upper contact of cam 359 to conductor 376 which is the-connecting conductor for 1.

ground on cam 251. Consequently, as switch 357 advances between positions 7% to 8% the locking circuit depends on the condition of relay 369. If this relay is operated because the digit is zero, all the counting relays of the third set will release. Otherwise, they will remain locked to the holding circuit on the left lower contact of cam 359 when position 8% is passed. With all the counting relays released, ten selection impulses can he received. It will be remembered, however, that the release of all counting relays furnishes eleven impulses in" all, so that it is necessary-to utilize but ten impulses to reach the tenth level. When switch 357 passes position 9%, therefore, a passing circuit is closed from ground on cam 251 over conductor 373, cam 301 and left lower contact thereof, right outer back contacts of relay 348, upper contacts of cam 361, left inner back contacts of relay 351, right back contacts of relay 328 to the winding of relay 322. Relay 322 operates and when thev switch passes position 9 and ground is removed,

relay 328 Operates and locks in series with relay 322. This operation will permit the third o ifice selector to choose the tenth level in case thesecond digit dialed is zero.

Selections by the third office selector now take place in position 10% of switch 357, the

relay simi ar to relay 130 in the third oflice' fundamental circuit being closed over the following ath: battery to the winding of a conductor 143 and associated terminal, left back contacts of relay 226, right outer back contacts of relay 224, windin of relay 225, left inner back contacts of re ay' 229, upper contacts of cam 257, right outer back contacts of relay 226, conductor 146 and associated terminal, conductor 147 and associated brush, right lower and upper contacts of cam 150, conductor 148 and associated brush, conductor 149 and associated terminal and brush, to ground, not shown, in the third office selector. The front contact of'the outstepping relay 225 is directed to the third set of counting relays over .the following path: ground on contacts of relay 225, upper contacts of cam 241, left lower and right upper contacts of cam 258, conductor 382, to the right back contacts of relay 329.

Pulsing operations between the main sender I and the third oifice selector now take place in the same manner as previously described for selections at the two preceding selector stages. When the number of revertive impulses necessary to satisfy the main sender have been received, the fundamental circuit is opened by the operation of relay 224 as previously described and an aforetraced circuit is closed from ground on thecontacts of relay 226 to advance switch 357 to position 11 In position 11% the switch 357 stops during the interval that the third ofiice selector hunts for an idle outgoing trunk to the distant oflice. When connection to said trunk has been made, a loop circuit is closed in the third ofiice selector for a series circuit between relay 227 and resistance 294 as in a previous selection and operates relay 227. Relay 227 closes a ground on its front contacts to conductor 279, upper contacts of cam 367, winding of rela 356 to battery. Relay 356 operates and loclZs to the same operating ground and, on its left front contacts, closes a ground from cam 274, cam 358 and left lower contact thereof, left front contacts of relay 356 to the winding of magnet 357 thereby advancing switch 357 to position 12%. As the switch passes from position 11 the circuit of relay 227 is opened at the right lower contact of cam 257 thereby causing this relay to release as likewise relay 356 will release also. When the switch reaches position 12 a ground on the right inner front contact of relay 222 is closed on conductor 280 to the upper left and lower right contacts of cam 368, the back contacts of relay 356 to the winding of magnet 357, advancing switch 357 to position 13 In po-.

sition 13 a circuit isclosed to operate relay 226 from ground on the left inner front contacts of relay 347, conductor 379, right upper and lower contacts of cam 259, winding of relay 226 to battery. Relay 226 operates and serves to control operations from the auxiliary sender as described herein-. after.

The connection has now been extended through the district selector, the special service second ofiice selector and a third office selector to the outgoing trunk shown in Fig. 6 which trunk extends to the automatic switches in the distant terminating oflice over conductors 621 and 622;

We will now describe the operations which take place in the auxiliary sender, understanding that these operations have been taking place simultaneouslywith these described above.

In the first lace, it is necessary to indicate to the aux1liary sender how many digits will comprise the number of the wanted subscriber since all of these digits have to be repeated to the distant office. This information depends on the character of the second digit dialed. When, therefore, sequence switch- 357 completes special service second oflice selections in position 5 and thereafter advances to position 10 a check is made to determine if the digit is more than four or less than five. than four, counting relay 330 is operated and the following circuit is closed for relay 352; battery and winding of relay 352, right inner front contacts of relay 330, right outer back contacts of relay 354, conductor 390, right middlefront contacts of relay 222, right lower contact and cam 242, cam 251 to ground. On the'other hand, if the digit is less than five, relay 330 will be normal and the following circuit is closed for relay 353; battery and winding of relay 353, left outer back contacts of relay 330, right outer back contacts of relay 354, conductor 390, right middle front contact of relay 222, right lower contact and cam 242, cam 251, ground. The

contacts of relay 353 and those of relay 352 are wired to the counting relays 318-331 in such a manner that the relays operated in response to the number of impulses constituting the second digit will ground the correspondingly numbered terminal 1, 2 0 of the contacts of these relays. Now the wanted subscribers number may consist of either 4, 5 or 6 digits'as already described, so that these terminals are cross-connected to conductors 276, 277 and 278 in any manner suitable to the operating company in respect to the'relation between the numerical value of the second digit and its corresponding interpretation in terms of the fundamental equivalent number of 4, 5 or 6 digits. Conductor 27 8 will be grounded if the fundamental subscriber number is to be If the digit dialed is more four digits, conductor 277 will be grounded for five di 'ts and conductor 276 will. be

ounded or six digits. According, thereore, to the second 1git received, aground will be connected to one of the three conducated terminal on auxiliary finder bank, conductor 473 and associated brush, middle right contacts of relay 454, conductor- 570, upper contacts of cam 557 conductor 486 winding of relay 455 to battery. Ground on conductor 277,;fif the fundamental number is to be a five-digit number, operates relay 456 over the following circuit: ground on conductor 277 and associated terminal on the auxiliary finder bank, conductor 47 4-and associated brush, right inner contacts of relay 454, conductor 571, conductor 572, left upper and right lower contacts of cam 553, conductor 573, winding of 456to battery. Finally, ground on conductor 276, if the fundamental number is to be a six-di 't number, operates relay 457 over the ollowing circuit: ground on conductor 276 and associated terminal on the auxiliary sender finder bank, conductor 472 and associated brush, right outer contacts of relay 454, conductor 574, right lower and left upper contacts of cam 463, winding-of relay 457 to battery. When any one of these relays operates it looks to ground on cam 558 over the right upper contact of cam 468, conductor 476 to ground on cam 558. Any one of these relays also closes the following circuit to switch magnet 544 to advance the switch from position 2 to position 4: ground through the left lower and upper contacts of cam 566 of the impulse switch 545 which is normal, conductor 575*and left inner contacts of either relay 455, 456 or 457, left lower contact and cam 460, conductor 477, cam 561 and left upper contact thereof, to the winding of magnet 544. If, for any reason, impulse switch 545 is not in the normal position, sequence switch 544 will stop in position 2 and a ground is applied from the left upper contact of cam 555 over the left outer back contacts of re lay 542 and right back contacts of relay 535 to the left upper contact of cam 565 causing switch 545 to be advanced to position 1 immediately after it had arrived in position 18.

When position 2 is passed, the circuit over test brush associated with conductor 567 is opened at the left lower contact of cam 551 so that the circuit is now holding thru the circuit over conductor 569 and associated terminal from this moment. Further, while pasing thru positions 2 and 3, ground from the right outer front contacts of relay 530 is transferred to the right upper contact of cam 550 independent of relay 529. In position 3 relay 528 is connected inparallel with the test relay 527 over the right upper contacts of cam 551 and the left outer front contact of relay 530. to conductor 569 so that this relay now operates and prepares, on its front contacts, a holding circuit for relay 530 over the right outer front contacts of relay 530 and the left lower contact of cam. 550. After position 2% is passed, relay 527 is disconnected and, when the right upper contact of cam 550 opens, the holding circuit of relay 530 is now controlled exclusively by relay 528 which,

in. turn, is held energized from the main sender. Relay 528 is such that it will hold in series with high resistance 369, and test brush associated with conductor 567 is now entirely insolated.

Sequence switch 544 now waits in osition 4 until the main sender has complete the selections to the outgoing trunk circuit towards the distant area, as already described, and has connected the'fundamental circuit from this trunk circuit through conductors 473 and 474 and their respective associated brushes. Further, when switch 544 arrives in position 3 a passing circuit is closed from ground on the left upper and lower contacts of cam 566, conductor 575, left inner front contacts of either relay 455, 456or 457, left lower contact and cam 460, conductor 47 7 cam.561 and left lower contact thereof, left middle front contacts of relay 530, conductor 576 and associated brush, conductor 391 and associated terminal, right upper and lower contacts of cam 366, winding of relay 354 to battery. Relay 354 operates and locks over its right outer front contacts, conductor 390, right middle front, contacts of relay 222, right lower contacts and cam 242 to ground on cam 251. Relay 354 opens, at its right outer front contacts, the circuit of relays 352, and 353 so that the brushes connected to conductors 278, 277 and 276 are free from this moment and are available for other uses.

We will now describe how the various digits, which will be received in the auxiliary sender, are stored in the sets of counting relays of the auxiliary senderand how, thereafter, the fundamental subscribers number is repeated to the distant oflice.

The counting relay registering circuit of the first digit that has to be stored in the auxiliary sender is directed from the back contacts of relay 200 over the front contact of relay 207 to conductor 471 and associated brush over the indialing pulsing circuit previously described. The impulses, when arriving, will operate relay 524 which is connected to conductor 471 and associated brush by way of conductor 478. The impulses will also besent over the back contacts of relays 453, 452, 451, 450, 449 and 448 to the first set of counting relays 401-410 in a similar manner to that already described in connection with the storing ofimpulses in the various III sets of counting relays in the main sender. When the series of impulses which forms the first digit dialed in the auxiliary sender is over, relay 524 releases and completes a circuit from ground on its back contacts, conductor 577, right front contacts of one of the upper set of counting relays and left inner back contacts to the winding of relay 448. Relay 448 operates and locks over its outer left front contacts, which are made to close before the back contacts mentioned above are opened. Relay 448, by energizing, transfers the indialing circuit on conductor 471 and associated brush to the next set of counting relays 413-422. The second digit will now be stored on this set of relays and, at the endof the digit, relay 524, by again releasing, will close a circuit for relay 449 over conductor 577 and a counting relay in the upper set of the second set of counting relays. Relay 449 looks in the same way as described for relay 448. Relay 449, by operating, transfers the in-dialing circuit to the next set of counting relays 425434 and, in the same manner as described, the next digit is stored on this set of counting relays.

When switch 544 arrives in position 4 as already described and the connection has been extended to the outgoing trunk shown in Figure 6, the low resistance windin of relay 533 is connected in series with relay 610 of the outgoing trunk circuit. The path is traced as follows: ground through the winding of relay 533, left lower and upper contacts of cam 560, conductor 571, inner right contacts of relay 454, conductor 47 4 and associated brush, conductor 277 and associated terminal, right outer front contacts of relay 226, conductor 146 and associated terminal, conductor 147 and associated brush, right lower and upper contacts of cam 150, conductor 148 and associated brush, conductor 149 and associated terminal and brush conductor 625 and associated terminal and brush, conductor 624 and associated terminal, top back contacts of relay 600, repeating coil winding 618, winding of relay 610 to battery. Relay 533 -energizes in the above circuit and advances sequenceswitch 544 from position 4 to position 8 in a circuit from ground on cam 5.58, cam 556 and right upper contact thereof, right front contacts of relay 533, winding of magnet 544 to battery.

In the trunk circuit, relay 610 energizes and, in turn, energizes relay 616 from ground on its right inner front contacts through the right back contacts of relay 617 to the winding of relay 616. In the meanwhile, when the third oflice selector established a connection with the outgoing trunk, a ground from the third office selector was passed over conductor 623 through the normally made left contacts of relay 617 to the winding of relay 615, causing 615 to operate and lock to the same ground over its left front contacts and left normal contacts of relay 614. Relay 616 when operated, removes ground from the winding of relay 614 at its left back contacts. The-third ofiice selector, provides a battery impulse through a resistance, not shown, on conductor 620 towards the. trunk circuit after relays 610 and 616 are energized and have removed ground to relay 614 so that relay 614 is prevented from energizing on this battery impulse. Relay 610, when energized, provides a ground from the right outer back contacts of relay 612 over the left front contacts of relay 610 to the winding of relay 602 which operates and connects trunk line conductors 621 and 622 over its top and bottom front contacts respectively and back contacts of relay 604 to a source of alternating current 634. The alternating current impulse which is thus sent out on the line will start the call at the distant end and cause the connection of a sender or selector or both at that end to the trunk line conductors 621 and 622. Further, relay. 602 by energizing, opens a ground on its bottom inner contacts which would otherwise be connected over the right front contacts of relay 610 to the winding of relay 614 and cause relay 614 to operate over the battery impulse above mentioned.

In the auxiliary sender, relay 533 is disconnected from conductor 571, conductor 474 and its associated brush after the switch passes position 7. The period between positions 4 and 8 of switch 544 is long enough to insure that the battery impulses mentioned above on conductor 620 have terminated when ground is disconnected from conductor 474 .in the auxiliary sender, thus causing the release of relays 610 and 602 in the outgoing trunk. Relay 616 will then look over its left front contacts through the right winding of relay 617 to ground on the right front contacts of relay 615. Relay 617 operates and applies a ground over its right outer front contacts and the right front contacts of relay 616 to the winding of relay 614. At the same time, the operating circuit of relay 615 is opened at its left contacts so that this relay is left locked through its left front contacts only and relay 617 is connected with its left high resistance winding to conductor 623. This circuit condition will now remain unchanged so long as the ground is left connected to conductor 623 from the third office selector. Further, relay 617 connects a ground from its'right outer front contacts over the right back contacts of relays 613 and 608 to the winding of relay 601 which thereby operates and connects the alternating current relay 606 across conductors 621 and 622 of the trunk.

As soon as the impulse receiving equipment at the distant end of the trunk has been

Images