US1839460A - Telephone system - Google Patents

Description

Jan. 5, 1932. J. I. BELLAMY 1,839,450

TELEPHONE SYSTEM Filed March 17, 1928 3 Sheets-Sheet 1 Jan. 5, 1932. J. l. BELLAMY 1,839,460

TELEPHONE SYSTEM Filed March 17, 1928 s Sheets-Sheet 2 J: 1111 Bellamy Jan 5, 1932. J. 1- BELLAM Y 7 1,339,450

TELEPHONE SYSTEM Filed March 17, 1928 3 Sheets-Sheet 3 John I. Bellamy M M- Patented Jan. E5, 1 9 32- UNITED srAras PATENT OFFIECE JOHN I. BELLALIY, OF BROOKFIELD, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO ASSOCIATED ELECTRIC LABORATORIES, INC., OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE TELEPHONE SYSTEM Application filed March 17, 1928.

The present invention relates to telephone systems in general, but is concerned more particularl with automatic telephone systems employmg register senders, although certain of its features are not confined specifically thereto.

One object is the production of new and improved circuit arrangements whereby the setting of the translator switch in a register sender under the control of registering apparatus is accomplished in accordance with connections common to a plurality of register translators, thereby avoiding the necessity of providing special cross connections in each individual register sender set.

It is a further object of the invention to provide circuit arrangements whereby the operation of the translator switch may be carried on in successive stages as the digits to be translated are received so as to enable the translating switch to complete its hunting operation more quickly following the receipt of the last digit to be translated.

A further object of'the invention is the production of arrangements for automatically dvancing the translating switch through spar positions to which no offices have been assigned, and for preventing the translating switch from stopping in any one of these spare positions responsive to any possible setting of the registering apparatus.

A further object of the invention is the production of suitable arrangements for performing a special operation, which consists in freeing the register sender and giving the calling subscriber a special tone when he sets the office-registering apparatus into a position which does not correspond to any assigned oflice.

A further object of the invention is product-ion of a new and improved relay arrangement for generating accurately-timedimpulses, which device may be readily adjusted so as to give a greater or a lesser time during an impulse cycle, and which may be separately adjusted to secure the desired ratio between the closed and open portion of a complete impulse cycle.

A further object of the invention is the production of a new and improved impulse cor- Serial No. 262,575.

recting repeater which will receive impulses I pulses of a xed pro-determined length. A

special feature of the new impulse correcting device is that the length of the impulse which it sends out is not readily susceptible to changes in the voltage of the battery from a which it obtains its operating current.

Another object is the production of a new and improved switch-control circuit, to be used in the switches operated by the register senders, which makes use of windings on the control relays for securing their slow action instead of the usual copper collars, thereby enabling the relays to become saturated more quickly upon energization.

A further object is the production of a new and improved-trunking arrangement for using a plurality of levels per group at selectors that have only a few outgoing trunk groups, thereby decreasing the trafiic per selector per level so as to enable trunk economy to be effected owing to the increased multiplying flexibility.

Other objects and features, for the most part more or less incidental to the foregoing, will appear upon a further perusal of the specification in connection with the accompanying drawings comprising Figures 1-4.

Referring now to the drawings, they show by means of the usual circuit diagrams a sufficient amount of apparatus in a telephone system embodying features of the invention to enable the invention to be understood. Fig. 1 is a schematic diagram indicating how two shelves of ten selectors each with their wipers suitably readjusted may be multiplied together and with other selectors in order to form aflexible and economical trunking arrangement. Figs. 2-4 show a complete register sender and a part of a switch train with which the register sender co-operates to extend connections.

In Fig. 2 there is shown a selector S (alsoindicated in Fig. 1) having access to two groups of trunk lines, one trunk line of each group beingshown. The trunk circuit TC is inserted in the'trunk line comprising conductors 201203 extending to the selector S and hasassociated therewith the registerthe usual release relay and the usual switch-:

ing relay of the trunk circuit preceding the firlst selector have been combined into a single ter sender, to ether with the common intermediate d1str1 uting frame I. D. F., 4, which is common to a plurality of re ster senders. The apparatus shown in comprises the re 'sters A, B, G for relgistering the three initial letters of calle oflic names, the thousands /hundreds, tens, and units registersfor registering the subscriber digits in called numbers, the sending switch, and the relays 311-315. g

The portion of he director shown in Fig. 4 includes the input control switch having wipers 411 and 412, the output control switch having wipers 404 and 405, the impulse generating and correctin relays 406-409, the translating switch T and the associated relays401, 402,414, 415,439, and 443-445. 80 As is explained in the detailed description of the operation hereinafter given, the translator switch TS, Fi 4, is arranged to be set under the control 0 the registers A, B, and C, Fig. 3, into any one of as many positions zli'as'there are ofiices in the system. The translator switch TS is a testing switch having the wipers 431 to 437 shown in the drawings and arranged to be rotated in a forward direction o 3 over bank contacts which may be arrange in a substantial semi-circle,.as in the 'case of a regular rotary lineswitch. The arran ement hereinafter described for settin t e translator switch TS into a desired position may be considered an improvement on the arrangement shown in Fi 6 of the Gillings Patent 1,705,462, issued arch 12, 1929, wherein the hunting switch HS is controlled by the three office-digit registers 0C 0G and 0G, to advance it to a position depend' g upon the composite setting of these three registers.

The number of contact sets in the bank of the translator switch TS may be from 25 to 100, depending u on the number of oifices in the systemin which the register sender'is installed. Ordinarily, the translator switch TS has more contact sets than there are oflices, thereby allowing for the addition of new offices as the telephone system expands. One spare set of contacts, reserved for future of- =fioe expansion, is shown in Fig. 4.

Since each of the registers A, B, and C of Fig. 3 have ten off-normal positions, these three registers can be set in any one of one 65 thousand separate combinations. Accordinga callin subscriber improperly operates his a, I Figs. 3 and 4 taken together show the regising line and places ground at i 1y, it may happen occasionall that the registers are set n accordance wit a combination not assigned to any ofiice, as for example when calling evice. For this reason, the upper set of contacts shown amociated with the transtion of calls wherein an unassigned ofiice designation is received, as will be explained in detail hereinafter.

The apparatus having been described in general, a detailed description of its operation will now be given. For this purpose it will be assumed that the trunk line comprising conductors 201-203, Fig. 2, is seized incidental to a call to a line te'rminatingin the oflice whose designating digits corresponding to the three initial letters of its name, are 3, 4, and 2.

When the trunk line is seized, the conductors of the calling line are extended to conductors 201 and 203, whereupon line relay 204 of the trunk circuit TC operates over the call- Rmiddle upper armature on release trunk conductor 202 so as to maintain the connection and to render the trunk line busy. At its inner upper armature relay 204 closes a circuit for relay 206 andstepping magnet 207 of the registerselecting switch RSS in series, and at its upper armature it connects test wiper 209 of the switch RSS to the junction of stepping magnet 207 and relay 206. As a result, relay 206 is short circuited and stepping magnet 207 is operated by a ground potential in case the register sender on which the wipers of the switch R SS are standing. is busy. Operating magnet 207 operates through its self-interrupting contacts and. advances the wipers 208-211 step by step in search of an idle register sender. Assuming that the register sendershown in Figs. 3 and 4 and reached over conductors 212-215 is the first one found'to be idle, the wipers of the switch RSS come .to rest when they reach the bank no contacts associated with this register sender, due to the absence of ground potential on. conductor 213. At this point, relay 206, being no longer short circuited, operates in series with magnet 207. Magnet 207 does not operate at this time due to-the relatively high resistance of relay 206. Upon operating, relay 206 places a multiple ground connection on release-trunk conductor 202 at its upper armature so as to maintain the trunk no line guarded during the impulsing action of line relay 204, which is subsequently to take place; it opens a point in the test circuit and grounds wiper 209 at its inner upper armature thereby grounding conductor 213 so as to guard the seized register sender; and at its remaining armatures it connects up wipers 208, 210, and 211.

Line relay 221 of the selector S now pulls up over conductors 214 and 215 and wipers 210 9 v 4 and of the registers in Fig. 3.

circuit for relay 222 through the upfier winding of series relay-223 and vertica magnet 226. Relay 222 operates in this circuit but rela 223 does not operate due tothe rela tive y high resistance of relay 222. -'Ver-' tical magnet 226 fails to operate for the same reason. It will be noted that while the contacts of relay 221 are in mid position there is a shunt around the high resistance relay 222 through the lower resistance winding of relay 223. Relay 223 and vertical magnet 226 would operate as a'result of-this condition except for the factthat the condition 6 exists during only an extremely short time as the contacts pass from one position to another. Upon operating, relay 222 makes a multiple ground connection to release trunk conductor 202 at its upper armature, and at its lower armature it opens a point in the circuit of release magnet 227 and locks itself to battery through the vertical magnet 226, thereby shunting the upper winding of relay 223.

In the register sender, release rela 312 Fig. 3operates over release trunk con uctor 213 when the said conductor is grounded as above described, and prepares the register senderfor operation by ungrounding restoring conductors 302 and 304 of the output control switch in Fig. 4 and release conductor 306 of the input control switch of Fig.

When the calling subscriber dials the first oiiice digit 3, line relay 204 of the trunk circuit TC falls back three times momentarily. Each time it falls back, relay 204' opens the circuit ofslow'acting relay 206 at its inner upper armature, but relay 206 is sufliciently slow to release that it remains operated throughout the series of impulses. As a further result of each deenergization of relay 204, a circuit is closed at the lower armature of the relay, through the lower contacts of relay206, wiper 208, conductor 212, series relay 415, Fig. 4, wiper 412 and the bank contact on which it is standing, and the as sociated conductor to the operating magnet of the register A, Fig. 3. In response to the three impulses received over the above traced circuit, the operating magnet of register A advances,-the wiper of the register three steps into engagement with the third off-normal bank contact. Series relay 415, Fig. 4, operateswhen the first impulse current is transmitted through it, and, being slow acting, remains operated throughout the digit. Upon operating, relay 415 operates the slow acting relay 414, with the result that a circuit is closed, when relay 415 fallsback, through contacts of relay 414 for operating magnet 410 of the input-control switch. This circuit is opened a moment later when slow acting relay 414 falls back again. Wiper 412, on advancing from its first contact'to its second contact responsive V tothe operation of magnet 410, 'sh1'fts'" the impulse. conductor from the operating magthe translating switch may start in a manner to be subsequently described.

When the second ofiice digit 4 is dialled, the four impulses are transmitted over a circuit as hereinbefore traced to wiper 412 and then by way of the second back contact thereof to the operating magnet of register B, Fig. 3, whereupon the wiper of register B is set. in accordance with the digit 4.

The input control switch of Fig. 4 advances axther step following receipt of the second o co digit with the result that the third digit is directed to the operating magnet of the register C, which register records *the third otfice digit 2. In a similar way, the

' wiper 412 lands on a dead contact and the wipers remain in this position until the register sender is released.

Returning now to the point at which relay 443 is first operated at the end of the registration of the first oflice digit due to the advance of wiper 411 of the output control switch relay 443 connects up relay 442 to the wiper oi register A at its upper armature, and at its lower armature it prepares a circuit for operating magnet 438 of: translator switch TS. At this point it may be pointed out that the circles to the left of the tapped battery, lo cated to the left of the intermediate distributing frame IDF and numbered 1 to 11, represent terminals to which other terminals represented by similarly numbered circles in Fig. 3 are to be connected. The interconnecting conductors have been omitted in the drawings in order to avoid undue complication and to render the drawing easier to fol- Assuming now that wiper 437 is standing on a bank contact cross connected to some battery tap other than No. 3,.relay 442 operates due to the difference in potential at its two terminals and closes a circuit for stepping relay 439. Relay 439 operates and closes a locking circuit for itself at its inner upper armature through contacts of crating magnet 438. Relay 439 alsocloses a circuit for operating magnet 438 at its lower armature and at its three upper armatures it disconnects relays 440-442 so as to prepare for the next step. Relay 442 falls back. When the operating magnet; 438 has completed its stroke, it opens the circuit of relay 439, .whereupon relay 439 falls back and opens the circuit of the operating magnet, at the same time connecting up relays 440-442 again. When the circuit of the operating magnet is opened, the magnet falls back and advances the wipers 431-437 one step. If the potential new placed on the left hand terminal of relay 442 through wiper 437 of the translating switch and the bank contact on which it is standing is difierent than the potential placed on the right hand terminal of the relay, the relay operates again, whereupon the translating switch is advanced another step.

When the wipers of the translating switch arrive upon the contacts assigned to an office whose first digit is 3, relay 442 fails to operate again because the same potential is now on both terminals, and the translating switch remains inert until the second digit is dialled,

as hereinbefore described, whereupon relay 444 is included in the circuit in series with relay 443 when Wiper 411 of the input control switch advances to its third contact at the end of the second digit. Relay 444 connects up test relay 441 to the wiper of register B, Fig. 3, with the result that relay 441 operates and closes a circuit for stepping relay 439 to bring about a further advance of the switch,

in case the potential encountered by wiper 436 of the translator switch TS and placed on the left hand terminal of the relayis unlike a potential previously placed on the right hand terminal of the relay when register B was set on its fourth off-normal contact. There may be in practice a number of ofiices all having the common first digit 3. Ordinarily, only a few of these ofiices will have the digit 4 as the second digit, and the translating switch will now be further advanced until the wiper 436 encounters the first bank contact cross connected to the No. 4 battery tap.

Upon the receipt of the third digit and the setting of the register C in the manner hereinbefore described, the output control switch includes relay 445 in series with relays 443 and 444 through contacts of the transfer relay 446, whereupon relay 445 operates and connects up test relay 440. The conductor now connected to the right hand terminal of test relay 440 has previously been connected'to the No. 2 battery tap by the wiper of the C register upon the response of this register to the third ofiice digit 2. As a result, relay 440 operates and causes a further stepping action of the translator switch TS until the wipers 431-437 arrive upon the bank contact set 342 shown in the drawings. In this position only, the potentials supplied to the left hand terminals of the rela 440-442 are, respectively, the same as t e potentials supplied to the right hand terminals of the relays, and no one of the three test relays can operate. Under this condition no further advance of the translator switch takes place and the stiflly adjusted transfer relay 446 operates due to the failure of stepping relay 439 tooperate. It will be noted that the circuit of relay 446 is prepared upon the operation of relay 445, at the end of the registration of the third oflice digit, and that the circuit of relay 446 is closed each time the stepping relay 439 is deenergized; Relay 446, being stifiiy adjusted, does not operate until/rela 439 remains deenergized for an apprecia le length of time. Upon operating, relay 446 locks itself to the grounded bank of wiper 411 at its upper armature, at the same time opening the circuit of relays 443-445, whereupon these relays fall back and disconnect the test relays 440-442. At its lower armature relay 446 extends ground over start conductor 447 to relay 407 of the impulse generating relays 406 and 407 so as to start the retransmission of impulses.

When ground is placed on start conductor 447, relay 407 energizes and closes a circuit for relay 406, at the same time placing ground on impulse conductor 448. Relay 406 energizes and opens the circuit of relay 407, with the result that relay 407 shortly falls back and opens the circuit of relay 406 and removes ground from impulse conductor 448. Relay 406 falls back and recloses the circuit of relay 407, whereupon relay 407 operates again. This operation continues in this manneras long as there is a ground potential on start conductor 447. The copper collar on the core of relay 407, as indicated by the black upper portion of the relay core, is placed on the armature end of rather than on the heel end of the relay so as to render the relay slightly slow to operate, in addition to being slow to release. The operation may be further varied by giving relay 406 a relatively stifi adjustment so that it will not operate until the core becomes practically fully magnetized responsive to its circuit being closed. I

Each time ground is placed on impulse conductor 448 impulse-correcting relays 408 and 409 energize in series. Relay 408, being lightly adjusted, operates first and closes a locking circuit for itself and for relay 409 at its lower armature, and at its u per armature it prepares to ground impu se conductor 303. When relay 409 operates, shortly after relay 408 operates, it com letes the grounding of conductor 303 at its upper the relay armature; short circuits relay 408 at its lower armature; and at its inner upper armature itcloses a circuit for its two windings in series. The closure of this circuit is without immediate effect, however, owing to the fact that the upper winding of relay 409 is short circuited through the lower contacts thereof by the ground potential on conductor 448. After it is short circuited at the lower contacts of relay 409, relay 408 receives no current from the circuit including the exchange battery, but there is a circulating current set up through itswinding and through the lower contact of relay 409 due to the receding magnetism in its core, which renders the relay slow to release as is well known. As-

suming first that the impulse delivered by relay 407 .over conductor 448 to relays 408 and 409 is shorter than a standard impulse, relay 407 falls back before relay 408 falls back, but relay 409 remains operated through the-lower contacts of relay 408 until relay 408 falls back, maintaining the ground potential on impulse conductor 303. If, on the other hand, the impulse delivered by relay 408 is longer than a standard impulse, relay 408 falls back while relay 407 is still operated, and relay 409 remains operated through the lower armature of relay 407 for the duration of the impulse. In any case, relay 408 falls back, following its short circuiting at the lower contacts of relay 409, after a suflicient time has elapsed to transmit an impulse of standard length over conductor 303. When it falls back, relay 408 terminates the impulse at its upper armature, and at its lower armature it removes ground from impulse conductor 448.

When the ground potentlal is removed from impulse conductor 448 at the last point, either at relay 407 or 408 depending upon the adjustment of relays 406 and 407, the short circuit is removed fromthe upper windinglays 408 and 409 is repeated each time a ground potential is placed on impulse conductor 448.

It is to be noted that the impulses delivered by relay 408 will be independent of ,reasonable variations in the potential of the exchange battery owing to the fact that relay 409 is adjusted to operate when the current flow through its windings reaches a predetermined value. .If the potential of the exchange battery is high, this predetermined value is reached more quickly and relay 409 operates sooner following the closure of the circuit through relay 408 and the lower.

winding of relay 409, whereas if the voltage of the exchange battery is low relay 409 does not operate so quickly, but waits until the current value through the circuit of the two relays reaches the same point as before. It will be understoodof course that in either case relay 409 operates within a very small fraction of a second in the embodiment herein disclosed. It will be noted further that the variation in the time required for relay 409 to operate does not afiect the length of the impulse delivered over conductor 303, because, while-the circuit is prepared by relay 408, it is not completed until relay 409 operates to short circuit relay 408 and the circuit over conductor 303 always remains closed until relay 408 falls back responsive to being short circuited.

Return nowto the point at which the impulses begin to be placed upon the impulse conductor 303. Responsive to the first impulse on this conductor, operatingmagnet 316 of the sending switch Fig. 3 operates through contacts of stop relay 314 and, upon subsequently deenergizing when the 1mpulse is terminated, advances the wiper 317 and 318 one step. Although, at its left hand contacts, operating magnet 316 opens the bridge across the outgoing impulse conductors 214 and 215, there is a substitute bridge at this time closed through the upper contacts of pick-up relay 313. Upon each succeeding impulse, magnet 316 operates again and advances the wipers 317 and 318 one'step upon deenergizing at the end of the impulse. Upon the first step'of the wipers 317 and 318, Wiper 317 encounters a grounded bank contact, closing a circuit for pick-up relay 313. Relay 313 prepares the outgoing impulse circuit by removing the local shunt at its upper contacts, while at its inner contacts it closes a circuit through contacts of stop relay 314 and over conductor 301 for the operating magnet 403 of the output control switch, Fig.4. Magnet 403 operates and prepares to'advance the wipers-404 and 405 when it subsequently de-energizes.

With pick up relay 313 operated, each operation of magnet 316 results in an opening of the bridge across conductors 214 and 215, each such interruption being termed an impulse.

Referring now to the cross connections at the IDF, Fig; 4 it will be noted that the bank contact on which the first-digit wiper 431 of the translating switch is standing is cross connected to the sixth battery tap. This connection predetermines that the first digit transmitted will be the digit 6.

At the end of the first impulse transmitted over conductors 214 and 215 at the left hand contacts of operating magnet 316, the test wiper 318 is advanced one step to the No. 2 batterytap. By this arrangement, if the digit to be terminated is the digit 1,-current of the correct polarity flows through the polarized test relay 315 operating the relay to terminate the digit. In the present case, how.- ever, the digit to be sent is 6 and the potential placed on the left hand terminal of the polarized test relay 315 is the potent1al of the sixth battery tap causing current to flow through the polarized relay in the direction opposite to that in which it must flow in order to operate the relay. This current flow is over a circuit path including the lower contacts of stop relay 314, conductor 305, wiper 405 of the output control switch, wiper 431 of the translating switch TS, the bank contact on which it is standing, and the associated jumper on the intermediate distributing frame IDF to the No. 6 battery tap. Upon the next step of the wipers of the sending switch, wiper 318 encounters the No. 3 battery tap, whereupon a current flow 1n the same direction as before, but of a lessened intensity flows through the test relay. The

operation continues in this manner. until wiper 318 encounters the No. 6 battery tap at the end of the fifth transmitted impulse,a-t which time no current flows through the polarized test relay due to the fact that it is connected to the same battery tap at both terminals. However, upon the next step of the wipers, wiper 318 encounters the No. 7 battery tap, whereupon the current of the correct polarity flows between the No. 7 and the No. 6 battery tap through the polarized test relay over the circuit path above traced. The polarized test relay 315 now operates and closes a circuit for stop relay 314, whereupon stop relay 314 operates to terminate the digit. At its upper contacts, relay 314 places a short circuit across conductors 214 and 215; at its lower armature it disconnects conductor 305 from the polarized test relay 315 and transfers it to the polarized skip relay 311; at its inner upper armature it opens the impulsecircuit of magnet 316 and closes its restoring circuit through its self-interrupting contacts and wiper 317 and at its middle upper armature it opens the circuit over conductor 301 of operating magnet 405 of the output control switch and closes a locking circuit for itself. When this occurs, magnet 403 falls back and advances the wipers 404 and 405 one step, preparatory to the correct termination of the next transmitted digit.

Skip relay 311 does not operate at this time from conductor 305 owing to the direction in which it is polarized. The operating magnet 316 of the sending switch now buzzes rapidly under the control of the local interrupter contacts and advances the wipers 317 and 318 to their normal positions, whereupon the buzzing action stops due to the fact that wiper 317 encounters an ungrounded contact in its normal position. At this time the circuit of pick up relay 313 is opened, and

or to the tenth battery tap, predetermining that the next digit will be the digit'O, corresponding to ten impulses. It will be understood of course that the value of the various code digits may be assigned arbitrarily at the IDF in order to fit the trunking systerm that exists from the calling ofiice to the called oflice. Since the IDF connection is to the tenth battery tap, the sending switch of Fig. 3 continues to operate without reversing the current fiow through the polarized test relay 315 until wiper 318 lands u on the contact connected to the eleventh attery tap, after the tenth impulse has been sent out. When this occurs, relay 315 operates and terminates the. digit in the previously described manner.

The advance of the output control switch 1 from its second to its third position takes place in the manner described above, whereupon wiper 405 renders effective the third code wiper 433 of the translating switch. Since this wiper is standing on a bank contact cross connected to the seventh battery tap, the sending switch of Fig. 3 sends out the code digit 7, whereupon the output control switch is advanced another step.

When the output control switch advances at the end of the third digit, wiper 405 engages the bank contact connected to wiper 434 of the translating switch whose present associated bank contact is cross connected to the ski conductor, or the grounded pole of the exe ange battery. The advance of the output control switch, it will be remembered, occurs just at the end of the digit and responsive to the operation of stop relay 314. It will be recalled also that relay 314 at its lower armature disconnects the sending control conductor 305 from test relay 315 and connects it instead to the polarized skip relay 311. The upper terminal of the skip relay is connected to the No. 1 battery tap and the relay is polarized so that it will operate only when the lower terminal is grounded, the connection to any battery tap of a more negative polarity serving merely to send current through the skip relay in the reverse di- .interrupting contacts of the operating magnet of the output control switch for advancing the output control switch through the remaining code-digit position. It will be noted that the output control switch ma be advanced throughtwo or inore code positions, provided the corresponding contacts in the bank of the translating switch are connected to the grounded terminal of the exchange battery. v Upon being advanced through the fourth position, wiper 405, in its fifth position, extendsthe-contml conductor 305 to the wiper of the-thousands register of Fig. 3. Ordinarily, the calling subscriber dials the complete number without hesitation, in which case the thousands register is operated before the code digits have been sent out, and the retransmitting operation does not catch up with the registering operation. However, in case the callin subscriber has hesitated and has not yet dialled the thousands digit,-

the sending operation is held up because, the

stop relay 314 is maintained energized, after pick u relay 313. falls back over a circuit through wiper of the thousands register by potential supplied through skip relay 311 from the No. 1 conductor to the wiper of the thousands register through the lower armature, oper ated, of stop relay 314 and over conductor 305 and wiper 405 of the output control switch. In this case, the stop relay remains energized and holds up the testing operation until the thousands register is operated. Since the output control switch has advanced beyond the influence of skip relay 311, it is immaterial whether this relay'responds or not.

Assuming now that the subscriber has dialled the number without hesitation, the sending operation continues and the thousands digit is terminated in accordance with the setting of the wiper of the thousands register to which the left hand terminal of the polarized test relay 315 is connected after stop relay 314 falls back.

The usual advance of the output control switch takes place following the termination of the thousands digit, whereupon the hundreds,-tens, and units digits are retransmitted in the same manner.

When the output control switch advances another step at the end of the units digit, wiper 405'encounters its last bank contact, placing a potential on conductor 212 which is obtained over conductor 305 through contacts of stop relay 314 from the No. 1 battery tap and through skip relay 311. The placing of this potential on conductor 212 closes a circuit through wiper 208 of the register selector RSS and through contacts of relays 206 and 204 for switching relay 205 of the trunk circuit TC. Switching relay 205 operates and locks itself to the grounded release trunk conductor 202 at its inner lower igit the first contact in the bank of the armature and at its upper and lower armatures it disconnects conductors 201 and 203 from linerelay 204 and extends them to the corresponding conductors of the selector S, thereby placing the maintenance of the established connection under direct control of the calling subscriber.

Relay 204 falls back responsive to its disconnection by relay 205 and it opens the circuit of slow acting relay 206. Relay 206 falls back after a slight interval and frees the register sender by disconnecting the wipers 208211 of the register-sender selector.

In the re ister sender, release relay 312 falls back w en the register sender is freed and it grounds release conductors 302, 304, and 306, causin the operated apparatus of the register sender to restore to normal. The restoration to normal of the output control switch is accomplished through the last contact in the bank-of wiper 404 and the selfinter rupting contacts of the operating magnet 403.

The restoration to normal of the input control switch is accomplished by release magnet 413'which operates from conductor 306 through the associated ofi-normal conis grounded by relay 312 so as to insure the advance of the output control switch to its second, third and fourth positions in case of a premature release due to the calling sub scriber hanging up his receiver while the sending operation is in progress. The release of the in ut control switch results in wiper 411 opening the locking circuit of relay 446, whereupon relay 446 ungrounds start conduct-or 447, permitting the relays 406-409 to cease their operation.

Now, when the first train of impulses, representing the digit 6, is transmitted to the selector S over conductors 214 and 215 from the sending switch, line relay 221 of the selector S falls back momentarily six times. Each time it falls back, relay 221 shunts relay 222 by connecting the lower winding of relay 223'in parallel with the winding of relay 222. It is to be noted that the upper winding of relay 223 is open circuited at this time to permit the current flow to build up quickly in relay'223. Relay 222 is maintained operated while shunted by relay 223 due to the circulating current through relay 222. Relay 223 and magnet 226 operate in series.

Each time relay 221 reoperates,it removes the shunt from around .relay 222, after replacing the upper winding of relay 223 in a circulating current in its upper winding.

"terrupter contacts.

Each time relay 221 releases again, vertical magnet 226 operates again and another current flow takes place through the lower winding of'relay 223.

At the end of the vertical movement of the selector, wipers-229231 have been raised opposite the sixth level of bank contacts by the six operations of vertical magnet 226, and relay 223 shortly falls back owing to the cessation of the circulating current in its upper winding, starting the hunting of the selector. The circuits are prepared for hunting action of the selector upon the first ofi-normal movement of the selector when relay 224 operates through the contacts of the operated relay 223, the associated oil-normal contacts, and

/ the interrupter contacts of i'otary magnet 2 28.

Relay 224 looks itself to release trunk con- .ductor 202 at its upper armature and prepares a circuit for rotary magnet 228 at its lower armatures. Then, when relay 223 falls back at the end of the vertical movement, the prepared circuit of the rotarymagnet is closed whereupon the rotary magnet operates, advancing the wipers 229-231 one step into engagement with the first set of bank contacts in the sixth level. Near the end of its stroke, magnet 228 opens its interrupter contacts, whereuponstepping relay 224 falls back and opens its own locking circuit and the rotary ma net circuit. The rotary magnet now falls bac and closes its interrupter contacts again.

The further operation of the selector depends upon whether the trunk line terminating in the first set ofbank contacts is busy or idle. If the first set of contacts tests idle,

- switching relay 225 now operates, seizing the connected trunk line. If the first set tests busy, relay 225 is short circuited by the ground potential encountered on the busy test contact by test wiper 230 and does not operate. This same ground potential is extended through the ofl-normal contacts of the selector and the interrupter contacts of rotary magnet 228 to stepping relay 224, which relay operates and causes a further advance by closing the rotary-magnet circuit.

This alternate operation of rotary magnet 228- and stepping relay 224 continues until an idle trunk line is reached. It will be assumed that the trunk line comprising conductors 232234 s found to be idle and is therefore seized. When this trunk line is reached, switching relay 225 is not short circuited and it operates from the grounded release trunk conductor 202 in series with stepping relay 224 through the associated oil-normal and in- Relay 224 does not operate in series with relay 225 owing to the rela-' tively high resistance ofthe latter. Upon operating, relay 225 opens the vertical magnet operating circuit and a point in the release magnet circuit at its inner lower contacts,

leaving relay 222 energized through contacts of relay 221 and the upper winding of relay 223. At its inner upper contacts, opens a point in the test circuit and connects wiper 230 to the rounded release trunk conductor 202, thereby making the seized trunk busy immediately. At its upper and lower armatures, relay 225 disconnects the incoming talking conductors from relay 221 and extends them through wipers 229 and 23l and the bank contacts on which they are standing to conductors 232 and 234 respectively of the seized trunk line. The line relay of the seized ctrunk line (not shown) now operates and causes the associated release trunk conductor 233 to be grounded in the usual manner so as to hold up the connection from the seized trunk line. Line relay 221 falls back responsive to being disconnected by-relay 225, and places the lower winding of relay 223 in shunt of the winding of relay 222, at the same time opening the initial energizin circuit of relay 222. Since the locking circuit of relay 222 is now open at the inner lower contacts of relay 225, no further current flows through this relay from the exchange battery, but the relay does not fall back immediately due to the circulating current through its winding in series with the lower winding of relay 223. After an interval, relay 222 falls back and prepares a. circuit for the release magnet at its lower armature, removing one ground connection from conductor 202 at its upper armature.

relay 225 v Responsive to the remaining trains ofimtion may take place as desired. The connection is. released in the usual manner when the receivers are replaced upon the termination of the conversation.

The releaseof the selector S takes place responsive to the removal of the ground potential from release trunk conductor 233 of the trunk line, which results in the deenergization of switching relay 205 of the trunk circuit TC and in the deenergization of switching-relay 225 of the selector S. When relay 225 falls back it closes at its inner lower contacts a circuit through the lower armature of relay 222 and the associated off-normal contacts for release magnet 227, the operating current being obtained from the lower winding of relay 223 through the normally closed contacts of line relay 221. The release magnet 227 and relay 223 operate over this circuit, but relay 222 does not operate owing to the relativelylow resistance of relay 223. Relay 223 closes a circuit through the associated oil-normal contacts and interrupter contacts for relay 224, which operate and extends this operating ground potential to release trunk conductor 202, thereby noted that the spare set of guarding the selector during the releasing operation. When the normal position is reached, the release magnet and relays 223 and 224 fall back. Relay 224 ungrounds conductor 202.

Referring now again to Fi 4 it will be bank contacts shown in the bank of the wipers 431-437 of the translator switch TS has one contact (the contact in the bank of wiper 437 associated with the A register, Fig. 3) connected to the unded terminal of the exchange battery. ince no contact ofv the A register is connected to the grounded terminal of the exchange battery, it is impossible for the translating switch TS to stop on this set of bank contacts because no setting of the A register will satisfy the required condition for stopping because there will be a potential difference across test relay 442 regardless of which osition theregister A is set in. Spare sets, it will be understood, may exist when there are fewer ofiices in the system than there are sets of contacts in the bank of the translator switch.

It will be noted that the upper set of contacts shown in connection with the translator switch is labelled, Unassigned-ofiice set. This set of contacts is reserved for disposing of calls wherein the setting of the A, B, and C registers, Fig. 3, does not correspond to any assigned ofiice. The contact in this set which is wiped over by the test wiper 437 associated with test relay 442 is connected to the grounded terminal of the exchange battery so as to prevent the translating switch from stopping on the unassigned-ofiice set. The relays 401 and 402 are provided to dispose of the call when the unassigned-ofiice set has been passed over the second time. If the setting of the A, B, and C registers is in accordance with any assigned ofiice, the translating switch will stop without making more than a single complete revolution.

In this connection, it will be recalled that relay 443 is operated to connect wiper 437 of the translator switch with the wiper of register A by way of test relay 442 at the end of the dialling of the first ofiice digit. It will be recalled also that, when this occurs, relay 442 controls the operating magnet 438 through the medium of stepping relay 439 to cause an advance of the wipers 431-437 until test wiper 437 encounters the same potential on which the wiper of register A has been set. When register B has been set, relay 444 is operated to complete a connection between the wiper of register B and the wiper 436 of the translator switch, whereupon the wipers of the translator switch TS are further advanced under the joint control of test relays 441 and 442 until a contactset is encountered in which the connections agree with the responsive potentials on which the wipers of registers A and B the control of all three test lelays 440-442. 1

It will be understood, of course, that the translator switch TS will never advance beyond the set of contacts assigned to the called ofiice as indicated by the setting of registers A, B, and C, because the advance'of the translator switch stops in any case when the potential or potentials encountered by the active testwiper or test wipers of the translator switchagree with the potentials preyiously connected up by the ones of the reg-' lsters A, B, and C that have been set. If there is only one assigned existing ofiice in the group of a possible one hundred offi'ces indicated by the first digit dialled, relay 442 alone will drive the translating switch until the contact group assigned to this ofiice is reached, and no further advance will take place responsive to relays 441 and 440 being connected up. Similarly, if the contact set to which the wipers of the translator switch have been driven in two successive movements under the control, first of relay 442 and then under the control of relays 442 and 441, is the only set corresponding to the first two oifice digits which have been dialled, then no further advance of the translating switch takes place when relay 440 is connected up, because the contact then engaged by wiper 435 is cross connected on the intermediate distributing frame IDF to the same potential which is encountered by the wiper of register C when it is properly set in accordance. to the digit assigned to the single oflice in the tens group indexed by the instant setting of registers A and B.

It is only when the registers A, B, and C of Fig. 3 are incorrectly set, so that their setting does not correspond to the digits of any assigned ofiice that the test wipers 437, 436, and 435 are unable to locate the same combination of potentials on a contact set, and the switch makes more than one complete revolution.

If the switch makes more than one revolution and therefore passes the unassignedin the special switch-through circuit at its lower armature. At its upper armature relay 402 operates relay 401 from the grounded release trunk conductor 212, whereupon relay 401 locks itself to conductor 212 and opens a point in the circuit of relay 402, at the same time preparing the special-switch through circuit. lVhen the wiper 431 passes oil the bank contact in uestion,.the circuit of relay 402 is opened w ereupon relay 402 falls back and opens a further point in its own circuit, leaving relay 401 locked up to conductor 213.

When the upper contact of the unassignedofiice set is again grounded upon the next passage of wiper 431, the ground potential fails to operate relay 402, because relay 401 is operated, and a circuit is closed through contacts of the non-operated relay 402 and through contacts of the operated relay 401 and over conductor 212 as above traced to the switch-through relay 205 in the trunk circuit TC. Relay 205 operates and switches the connection through, cutting 01f relay 204, which releases relay 206 to free the register sender.

It will be apparent that the above switchthrough operation takes place with the selector S non-operated because no digits can be sent out in any case until after the translating switch TS has completed its operation. Under this condition, the incoming conductors 201 and 203 are extended through to line relay 221 of the selector S, which line relay is ordinarily disconnected by the usual operation of the selector before the switching relay 205 operates. In this case, a special tone from the tone source through the transformer 212 is placed on the calling line through the lower winding of relay 221, informing the calling subscriber that the number is unobtainable and that he mustreplace his receiver and try again.

In order to prevent the possible completion of the connection to a subscribers line in case the calling subscriber should disregard the tone and continue to dial, the operating circuit of the vertical magnet 226 is opened at the upper contacts of relay 205 so as to prevent the vertical magnet from responding to deenergizations of line relay 221. The connection to the selector is released when the calling subscriber replaces his receiver.

Referring now particularly to Figs. 1 and 2, the modified trunking arrangement will now be explained. This arran 'ement can be understood best perhaps if reference is had to the Patent 1,633,118 granted June 21, 1927 to McElyea. By way of explanation, it may be pointed out that a switch such as S of Fig. 2 has its bank contacts arranged in ten horizontal rows or levels, ten sets of contacts per level. It is common practice in manufacturing and in installing these switches to install the switches in groups of ten, each group being called a shelf, there being a multiple from each contact in the bank of one switch to the corresponding contacts of adjacent switches, a connecting rack is provided comlnon to a plurality of shelves and a'cable known as a bank cable is run from each switch shelf to the frame. This cable contains as many wires as there are contacts in a switch bank. Each shelf is represented on the connecting frame by a set of contacts, to which the corresponding bank-cable wires are connected, and as many shelves as desired are multipled together as regards their several levels and are appropriately connected to trunk cables representing trunks extending to the next order of local switches or to inter oiiice trunk lines as the case may be.

\ In case there are ten similar trunk groups accessible to a group of selectors, the grouping is fairly simple, as the banks of ten shelves may be multipled together and connected to ten groups of outgoing trunk lines, one group per level. In this case there are 100 switches involved and there are 100 outgoing trunks.

Assume now that the traflic on one level of the group of selectors is slightly heavier than the traffic on any one of the other levels, the ten trunks carrying the load from that one level may become overloaded, in which case it is necessary to rearrange the multipling so that ten trunks will carry the load of possibly 8 or 9 shelves as regards the level in question. If the traflic were still heavier on the level in question ten trunk lines might be able to handle trafiic from only three or four shelves. Under such circumstances, with the level load as heavy as assumed, the addition of the traflic of another shelf onto a trunk group increases the total number of calls delivered into the group quite materially, and it is diiiicult to secure a fine distribution of the traflic in order to keep each trunk group working eificiently without being overloaded.

It may be pointed out that the condition such as outlined above of abnormally heavy traffic per shelf, per trunk group is rarely encountered when ten full levels of a group of selectors is working, because in that case the calls are ordinarily distributed more or less evenly over the various levels of the shelves, with the result that a level of a large number of shelves can be multipled together to send traflic into a group of ten trunks as above outlined. In case, however, there are only a small number of groups of trunks accessible to a, selector, two for example, a given shelf of switches will send approximately half the trafiio into a given trunk group if the calls are equally divided and more than half its traffic in one case if the trafiic to that trunk group is heavier. The same condition obtains but to a lessening degree as the number of trunk groups per selector group is increased from two up toward the full numeflicient use of the outside cable system rather than from the standpoint of the economy of switching .equipment. Now, if the register senders could be arranged to send their calls systematically to all levels of a selector group having only two groups of trunks outgoing therefrom, half the levels could be multipled into one group and half the levels into another group with the result that a fine distribu' 'tion of trafiie could be obtained.

The grouping of Figs. 1 and 2 is made under the assumption that there are only two trunk groups accessible to the first selectors in the oflice in which the equpiment shown is located. Of these groups, the one including the trunk comprising conductors 232234; is an outgoing group, while the roup includin the trunk comprising con uctors 235 237 is assumed to lead to local thousands se- 'lectors. Assuming that the local trafiic is substantially equal to the outgoing traflic, the calls will be fairly equally divided between the two groups. The outgoing group is arranged to receive traflic from the upper five levels of the selectors, while the localgroup is arranged to receive traflic from the lower five levels.- In order to direct the trafiie into the various levels, the re ister senders are arranged to send out the igit 6 if the call is outgoing and to send out the digit 1 if the call is a local call. In order to complete the distribution, the wi ers of the several switches on a given shel for example, shelf 1 of Fig. 1, are set in various positions. For example, the wipers of selectors 1 and 2 of Fig. 1 have their wipers set in the normal way, one-step below the lower bank level;

the wipers of selectors 3 and 4 of this shelf are set opposite the first level; the wipers of selectors 5 and 6 are set opposite the second level; the wipers of selectors 7 and 8 are set opposite the third level; and the wipers of selectors 9 and 10 are set opposite the fourth level. As a result, when the digit 1 is sent, the selector used may be operated to connect with a trunk line in any one of the lower five levels, depending upon the selector used, while if the digit 6 is sent the selector used may connect with any one of the upper five levels, depending upon which selector is used. It will be seen, therefore, that the trafiic from two selectors of the shelf of ten is sent out on each of the upper five levels to the outgoing group and sent out on each of the lower five levels to the local group. The trafiic therefore has been reduced to small another sub-group of ten trunks (S2) receives trafiic from the lower five levels of shelf 1 and from levels 4 and 5 of shelf 2. The third sub-group of ten trunks (S3) receives traific fromlevels 6, 7, and 8 of shelf 2, and there is a jumper extending down from this trunk group indicating that it receives traific from four shelf levels of the next shelf of the series. The same is true for the sub-group S4. From this it will be seen that either the local group (comprising sub-groups S2, S4, etc.) or (comprising sub-groups S1, S3,-etc.) can handle more than half of the total traflic but this is ordinarily necessary, due to the fact that the peak load on the outgoing group and the peak load on the local group do not ordinarily occur simultaneously.

If calculations or observations show that the formed groups of trunks can handle more traflic thanis being directed to them or that they are overloaded, the jumpering can be suitably rearranged and the adjustment can be finely made due to the relatively small traflic per shelf level offered by the improved arrangement hereinbefore presented.

As an alternative way of handling the sit- 1 stead of the staggered arrangement 1 lus- 1 trated and an approximately equal distribution of tralfic could be made by dividing the register senders into five groups. The register senders in group #1 would send trafiic out over the first and sixth levels by merely retransmitting the digits 1 and 6, as all the directors do in the arrangement above described; the register senders in group 2 would send out the digits 2 and 7 instead; the register senders in group?) would send out the digits 3 and 8; and so forth.

Although the arrangement of Fig. 1 has been described as of particular utility in connection with a multi-office telephone system employing register senders, this arrangement may often be used to advantage in other systerns not containing register senders. For example, in a 2000-line system the first selectors are thousands selectors. Now, if the digits 1 and 6 are assigned to the two thousand-line groups, respectively, the calls will be scattered throughout the ten levels of the selectors provided the wipers are readjusted Fig.

It is to be understood of course that the arrangement is not limited to the first se lectors but may be applied to any order of selcctors as the occasion may arise.

It is to be understood that, although the arrangement has been described in detail in connection with selectors having only two out-going trunk groups accessible thereto, the same arrangement may be applied to selector groups having any number of outgoing trunk groups up to five. For example, if there are five trunk groups accessible to a group of selectors the first five switches may have their wipers set in the normal way one step below the first level of contacts, while the second five switches of the shelf have their wipers standing just below the second level of bank contacts. In this case the digits assigned to the outgoing trunk roups are the digits 1, 3, 5, 7 and 9. The first five switches on the shelf send their traffic out over the levels 1, 3, 5, 7, and 9, while the remaining switches send their traffic out over the levels 2, 4t, 6, 8, and 10. As an alternative arrangement,

' the wipers of the second five switches of the shelf 10 may be set just below the sixth level instead of just below the second level, in which case the digits assigned to five outgoing groups are the digits 1-5, respectively. This results in the first five switches sending their trafiic out over the first five levels of the bank and in the last five switches sending their trafiic out over the upper five levels of to the same trunk group; likewisefl and 7,

a the bank. In this case levels 1 and 6 belong etc.

As an arrangement alternative to the one shown in Fig. 1, the digits 1 and 2 may be assigned instead of the digits 1 and 6. In this latter case the wipers of the selectors of a shelf are set as follows: switches 1 and 2 below the first level, 3 and 4 below the third level, 5 and 6 below the fifth level, 7 and 8' below the seventh level, and 9 and 0 below the ninth level. In this case, when the digit 1 is dialled the call may be sent out over either of the odd-numbered levels, while if the digit 2 is dialled the call may pass out over any one of the even-numbered levels, depending upon which switch handles the call.

Referring again to the impulse-correcting device shown in Fig. 4 and comprising relays 408 and 409, it will be apparent that, although this is shown in connection with an arrangement for transmitting impulses to' the sending switch of a register sender, it is readily applicable to impulse repeaters used in trunk lines to repeat impulses from one section to another andthat its impulse sending contacts may be suitably rearranged to send interruptions of a fixed length rather than closed impulses of a fixed length.

What is claimed is:

1. In a translating register sender for use in multi-oflice telephone systems, ofiice registers for registering the oflice digits, respectively, of telephone numbers, a wiper and a bank of contacts for each oflice register, multiple connections between the respective bank contacts of said oflice registers, a translating switch, and means for setting said translator switch in accordance with the composite setting of said ofiice registers, said means being controlled through said wipers and said multiple connections.

2. In a register controller for use in telephone systems, a translating switch having a" plurality of test wipers, cooperating bank contacts having a plurality of combinations of fixed test potentials thereon, testing apparatus controlled over said test wipers from said bank contacts, and digit-registering apparatus arranged to predetermine the combination of test potentials to which said testing apparatus will respond.

3. In a register sender for use in telephone systems, a translating switch having a plurality of sets of wipers and cooperating test bank contacts, said bank contact sets having fixed combinations of test potentials thereon, means including testing means for advancing said translating switch under the control of said test wipers and for stopping the switch with its test wipers in association with a bank contact set having a predetermined combination of test potentials thereon, and registering means for predetermining the combination of test potentials to which said testing means will respond to stop said switch.

4. In a register-sender system for use in directing the calls in a multi-oflice telephone system, a plurality of register senders each having a translating switch arranged to be set in accordance with the office-designating portion of called numbers, each of said translating switches having a plurality of test wipers and cooperating bank contacts for controlling the setting of the associated translating switch and a plurality of digit wipers and cooperating bank contacts for controlling the operation of the automatic switches, multiple connections between the contacts in the bank of the test wipers of-the several translating switches, and separate multiple connections between the contacts in the bankof the digit wipers of the several translating switches.

5. In a multi-oflice telephone system, a plurality of register senders each having a translating switch arranged to beset in accordance with the otfice designating portion of called numbers, each of said translating switches having a plurality of test wipers and cooperating bank contacts for controlling the setting of the associated translating switch and a plurality of digit wipers and cooperating bank contacts for controlling the operation of the automatic switches, multiple connections between the contacts in the bank Lesa-o of the test wipers of the several translating switches, separate multiple connections be tween the contacts in the bank of the digit wipers of the several translating switches, and 5 means common to all of said translator switches whereat the test value of an contact set may be simultaneously change in all of said translator switches.

6. In a multi-oflice telephone system, a plurality of register senders each having a translating switch arranged to be set in accordance with tne oflice designating portion of called numbers, each of said translating switches having a lurality of test wipers, and cooperating ban contacts for controlling the setting of the associated translating switch and a plurality of digit wipers and cooperating bank contacts for controllin the operation of the automatic switches mu tiple connections between the contacts in the bank of the test wipers of the several translating switches, separate multiple connections between the contacts in the bank of the digit wipers of the several translating switches, and means common to all of said translator switches whereat the test value of any contact set may be simultaneously changed in all of said translator switches, and whereat the digit value of any contact set may be simulao taneously changed in all of said translator switches.

7. In combination, a plurality ofregistering-devices having wipers and bank contacts, and means for setting each device independas ent of any other, a translating device having bank contacts and cooperating test wipers, multiple connections between the bank contacts of all said devices, and testing means controlled through said test wipers and test contacts in accordance with the setting of said registering devices for stopping said translating device in a position individual to any composite setting of said registering devices. 8. In combination, a plurality of registering devices and means for setting each mdependent of any other, atranslator switch having test contacts and cooperating test wipers, testing means controlled through said test wipers and test contacts in accordance with the setting of said registering devices for stopping said translating switch in a position individual to any composite setting of said registering devices, a plurality of other translating switches each having a plurality of controlling register devices associated therewith, and means whereby the position assigned in any translator switch to a given composite setting of the associated registering devices may be simultaneously altered.

9. In combination, a plurality of register switches and means for setting each independent of the setting of any other one, a translator switch, testing means for stopping said translator switch in, a position indiassociate vidual to any desired composite setting of said registers, a pluralit of other sets of register switches each set aving an associate translator switch, and meanscommon to all said translator switches for assigning at will the position in which the translator switches will stop in accordance with any predetermined settin of the respective associated register switc es.

10. In combination, a plurality of register switches and means for setting each mdependent of the setting of any other one, a translator. switch, testing means for stopping said translator switch in a position individual to any desired composite setting of said registers a plurality of other sets of register switches each set having an associated translator switch, and means for simultaneously altering the position in which the several translator switches will stop responsive to a (particular setting of the respective re 'ster sets.

11. In com ination, a plurality of register switches and means for setting them one after the other, a translator switch, means controlled b simultaneous testing means for settin sai translator switch in a osition indivldual to a composite setting 0 said registers, and means whereby the testing operat1on may be carried out in successive stages as the several digits are registered one after the other.

12. In a register sender for use in a multioflice telephone system, a translator switch of the type which rotates in a forward direction only, oflice registering apparatus for registering the oflice designation, means for taking a register sender or use and operating said translator switch under the control of the oflice' registering apparatus to a position corresponding to the called ofiice, register-sender freeing means prepared for operation upon the translator switch reaching a predetermined position for the first time, and means for operating said freeing means to free said register sender and to give the calling subscriber a special signal when the translator switch reaches the said predetermined position the second time responsive to the ofiice registering apparatus having been set in a position corresponding to an unassigned oiiice. r

13. In a register sender for use in telephone systems, a translator switch set under the control of a plurality of test wipers, and under the control of a plurality of digit registers, contacts in the bank'of said test wipers having predetermined test potentials thereon corresponding to settings of said registers, and means for preventing said trans- 125 lator switch from stopping in one of its unassigned positions by connecting a test contact of such position to a test potential, which does not correspond to any possible setting of said registers.

14. In an impulse repeating device arranged to receive a continuous series of impulses, a first relay arranged to operate and restore responsive to each incoming impulse, a second relay arranged to operate and restore responsive to each incoming impulse, contacts on the second relay for short circuiting the first relay, and an outgoing impulse circuit controlled by the joint operation of the two relays each time an incoming impulse is received.

15. In an impulse repeating device, a first relay arranged to operate and restore responsive to each incoming impulse, a second relay arranged to operate and restore responsive to each incoming impulse, contacts on the second relay for short circuiting the first relay, an outgoing impulse circuit, and contacts on said first relay effective each time the first relay responds to an incoming impulse to send an impulse over said outgoing impulse circuit of a length dependent upon the time required for said first relay to restore responsive to being short circuited.

16. An impulse correcting repeater responsive to incoming impulses to repeat corrected outgoing impulses comprising two impulse receiving relays connected in series, the second of said relays being stifily adjusted relative to the first, whereby the first relay operates before the second, contacts on the second relay for shunting the first relay so as to bring about its deenergization. and an outgoing impulse circuit controlled by the two relays jointly.

17. An impulse correcting repeater responsive to incoming impulses to repeat corrected outgoing impulses comprising two impulse receiving relays connected in series, the second of said relays being stifily adiusted relative to the first, whereby the first relay operates before the second, contacts on the second relay for shunting the first relay so as to bring about its deenergization. and an outgoing impulse circuit controlled by the first relay.

18. An impulse repeating device for repeating corrected impulses comprising two receiving relays with their windings connected in series, locking contacts on the first receiving relay for closing a locking circuit to maintain a current flow through the receiving relays independent of the sending source when the first relay responds to an impulse, contacts on the second relay for shunting the first relay to bring about its deenergization and an outgoing impulse circuit controlled by one of said relays.

19. An impulse repeating device for repeating corrected impulses comprising two receiving relays with their windings connected in series, locking contacts on the first I receiving relay for closing a locking circuit to maintain a current flow through the receiving relays independent of the sending source when the first relay responds to an impulse, contacts on the second relay for shunting the first relay to bring about its deenergization, and means including a differential winding and locking contacts on the second relay for securing a quick deenergization of the second relay at the termination of the incoming impulse.

20. In an impulse-repeating electromagnetic device arranged to receive impulses over an incoming impulse conductor and to repeat such impulses over an outgoing impulse conductor, means in said device responsive to each incoming impulse to repeat an outgoing impulse of a fixed length regardless of the length of the incoming impulse, a current source for supplying operating current to said device, said means being arranged so that the repeated impulse is substantially independent of minor fluctuations in the E. M. F. of said current source.

21. In a telephone system wherein a register set is associated with a trunk line through the action of a register selector having a line relay and a switching relay, a circuit for said switching relay controlled by said line relay, and a setting circuit for the seized register set including contacts of said line relay and contacts of said switching relay, said switching relay being slow acting whereby it does not fall back responsive to series of impulses transmitted to said register set but falls back responsive to a prolonged deenergization of the line relay.

22. In a telephone system wherein registering devices are associated with a trunk line through the action of a register selector having'a line relay and a switching relay, a circuit for said switching relay controlled by a line relay in the trunk circuit, a setting circuit for the registering apparatus of a seized registering device including contacts of said line relay and contacts of said switching relay, said switching relay being slow acting whereby it does not fall back responsive to series of impulses transmitted to said register sets but falls back responsive to a prolonged deenergization of the line relay, a release trunk conductor, circuit arrangement associated therewith whereby it is necessary to maintain said release trunk conductor continuously grounded, and'contacts on said line and switching relays for maintaining the ground potential on said release trunk conductor.

In witness whereof, I hereunto subscribe my name this 14th day of March, A. D. 1928.

JOHN I. BELLAMY.

Images