US1157881A

US1157881A - Machine switching telephone system.

Info

Publication number: US1157881A
Application number: US4283015A
Authority: US
Inventors: Frank Robert Mcberty
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1915-07-30
Filing date: 1915-07-30
Publication date: 1915-10-26
Anticipated expiration: 1932-10-26

Description

F. R. MCBERTYJ MACHINE SWITCHING TELEPHONE SYSTEM. APPLICATION FILED MAR.2. 1914. RENEWED IULY 30. 915- Pavtented Oct. 26, 1915.

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AMY.

F. R. McBERTY V MACHINE SWITCHING TELEPHONE SYSTEM APPLI'CATION FILED MAR.2. i914- RENEWED JULY 30.1915.

1,1571381. Patented 0ct.26,1915

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F. R.. McBERTY.

MACHINE swncHma TELEPHONE SYSTEM. APPLICATION FILED MAR. 2-1914- RENEWED JULY 30. IBIS.

Patented Oct. 26, 1915.

9 SHEEIS-SHEET 4.

W/fnesses:

' by I MAff' F. R. MCBERTY.

MACHINE SWITCHING TELEPHONE SYSTEM. APPLICATION FILED MAR.2. I914. RENEWED JULY 30.1915.

151573881. Patented w. 26, 1915 9 SHEEIS-SHEET 5,

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F. R. McBERTY. MACHINE SWITCHING TELEPHONE SYSTEM. APPLICATION FILED MAILZ. I914- RENEWED JULY 3011915. 1,157, 31, Patented (M26, 1915.

9 SHEETS-SHEET 6.

F. R. MCBERTY. MACHINE SWITCHING TELEPHONE SYSTEM. APPLICATION HLEDMAR. 2. 1914. RENEWED JULY 30. I915- 1 157 31 Patented Oct. 26, 1915.-

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Pateutd Oct. 20, 1915.

F. R. McBERTY.

MACHINE SWITCHING TELEPHONE SYSTEM.

APPLICATION FILED MAR. 2. 19M RENEWED JULY 30,19l5.

W/fnesses:

. Fran/r /'I. M

v F. R- MCBERTY. MACHINE SWITCHING TELEPHONE SYSTEM. APPLICATION HLED mm. 2. I914. nsmzwzn my 30. ms,

1,157,881. Patamad; Get 2%, 1915;,

9 sakes-swam UNITED sTA'rEs PAT NT "OFFICE.

FRANK ROBERT MCBERTY, OF ANTWEBP, BELGIUM, ASSIGNOR TO WESTERN ELECTRIC COMPANY, OF NEW YORK, N. Y., A CORPORATION OF ILLINOIS.

- MACHINE SWITCHING TELEPl -IONE SYSTEM.

Specification of Letters Patent.

Patented Oct. 26, 191 5.

Application filed March 2, 1914, Serial No. 821,875.. Renewed July 30, 1915. Serial No. 42,830.

To all whom it may concern Be it known that l, FRANK ltinnsirr ll/IUBERTY, a citizen of the United States, residing at 49 Boulevard Leopold, Antwerp, Belgium, have invented certain new and useful lmproven'ients in Machine Switching Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to improven'ients in machine telephone switching systems, and has to do more particularly with systems in which the extension of the desired connection from a calling line to a called line is ac complished by automatic switching apparatus directly or indirectly under the control of a subscriber at. the calling substation. Many of the features to be described, ho'w 'ever, are 'not restricted to systems of this In British Patents Nos. 26,079/10 and 21,259/11' there are described automatic telephone switching systems in which impulses transmitted from a calling station and representing the number of the wanted line are received at the central oflice by registering devices which thereupon act as controllers to govern the selecting operationsnecessary to extend the connection to the line represented by such registration. Furthermore, in British Patent No. 21,259/11 there is described a system and arrangement in which translation takes place in such registering and controlling devices whereby, although the controlling mechanism located at the substation may be constructed and operated according to one system of notation. the actual selection of the desired line and of the v l trunk l nes over which it may be reached may take place in accordance with some other system of notation,

One of the principal features of this invention relates to systems of the character described. in the patents referred to and relates more particularly to an improved and novel registering and controlling equipment and means for associating the same with the calling substation and the selectors to be controlled. Most specifically this feature.

of the invention involves the use of powerdriven registering and controlling devices in such registering and controlling equipment and of improved and novel circuitsand arrangen'ients whereby such devices may be controlled and operated accurately and at high speed to positively and precisely control the operation of the automatic switching devices to be selectively and accurately set in response to the controlling operation at the called subscribers substation.

Other novel features of the invention, such particularly as relate to operations of various sequence switches (steeringswitches) used therein and the inter-operation of such switches will.more fully appear from the detailed description of the invention.

In the drawings, Figure 1 shows the circuits and apparatus of a subscribers line and Fig. 1 the first line tinder adapted to extend the connection of such. line when calling; Figs. 2 and 2 illustrate diagrammatically the second line finder and the connecting circuit associatr-id therewith, together with the-group selector and other apparatus associated with such connecting circuit: Figs. 3 and 3 illustrate the circuits and apparatus of a final selector; Figs. l and 4. illustrate the circuits and appara tus of a registering and controlling equip ment adapted to be associated with the connecting circuit shownlfi Figs. 2 and 2, to control the group selector and final selector shown. Fig. 5 is a detail of the structure of the final selector showing wherein the final selectors used in the system disclosed dili'cr from the final selectors disclosed in the Britishlatent No. 21.259/11 above referred to. l igs..1,-'1, 2, 2. 3, 3. -l and. t taken together illustrate diagrammatically a system involving the invention. Fig. 1 should be placed to the right of Fig. 1, Fig. 2 to the right of Fig. 1. Fig. 2 to the right of Fig. 2, Fig. 3 to the right of Fig. 2. Fig. 3 to the right of Fig. 3-. Fla. 4 below Fig. 2, and Fig. 4* below Fig. 2".

The line finders. group selectors and sequence switches are of types already known made that in Fig. 2 the sequence switch confacts of the three sequence switches shown thereon are associated with, the sequence switch indicated in that portion of the figure separated from the rcn iaining portions by dotted lines. The nnal se ector switch differs from the final selector switches of this type previously known only by the.

addition of two extra notches in the interrupter plate 01 the top thereoi, between the first 10 notches thereof and the second tacts' of these lines are. arranged in ten levels of twenty lines each. Between the bank of the one hundred lines individual toone hundred, and the bank of lines individual to another hundred, that is to say, between the first tenlines of each level and the second ten lines of each level there is 'a' spacing plate. In selector switches of this type previously known the spacing between the two banks of line contacts was Without .efi'ect. as the interiupter plate at the top oi the selector-.Was uncut over the portion there: of corresponding to the spacing plate. in the final selector switches as used herein,

' however, there are two notches cut in the lines passed over plustwo.

portion. of the interrupter piate correspond-- .ing to the spacing plate for purposes herein described. That is to say, in. selecting a hue in the first set'bf ten lines on. a given. level. the interrupter will operate a number of times corresponding to the number of lines passed over, whereas, in selecting a line in the second set of ten contacts on such gi'vei'i level, the interrupter will operate a number of times corresponding to the number of This will be readily understood from an examination of Fig. 5 in which the notches 0; represent the notches of such interrupter plate corresponding to the first set of ten lines on the given level of the selector; the "notches 6 representthe notches in such plate corresponding" to the second set of ten lines on sequence switches 100arein first or normal position. Such idle line finders will, there- :t'ore, start in motion, moving their

brushes

125, 126, 127, 128 over the

terminals

129, 130, 131, 132 of thedines appearing in such line finders, and testing such lines in the usual way. As one of them, however, brings its brushes'into contact With. the terminals of the calling line, it will find upon the terminal 132 of such line a selectable potential produced by the energization of the line relay 121 and determined by the resistances 133'and 134. Immediately that the'brl'lsh 128 comes in contact with the terminal 132 upon which such selectable potential exists,

the first. line finders of this group which'are at this time in idle condition; that is, whose the test relay 135 will be energized over the springs 102 bottom, 108 top and either the spring 106' or the interrupter brush 136.

The cnergization of this relay 1,35 closes through. its armature a low resistance holding winding for itself, the closure of such circuit through such Winding so reducing the potential upon the terminal 132 that such potential is no longer selectable, and any other line finder whose brush 128 comes in contact with such terminal 132 will not be stopped. The carriage of the line finder "which has thus seized the line, continues in motion,'however, until its brushes are properly centered upon the terminals of the calling line, at Whichtime the circuit such level, and the two notches (I represent the two extra or additional notches which have been added as above indicated for purposes hereinafter described.

The invention as disclosed herein will be best understoodfrom a description or the ,operati m of thesystem shown.

Assuming that the sul'xscriber at the substation indicated at 120 desires conmiction with the subscriber indicated at 320, whose Iuunber is 307. he first removes his receiver from. its switch hook, thereby closing a circuit for the line relay 121 which, on its ener- ,Q'izaticn, closes a circuit tor and energizes the pilot 'relay'122 common to a group of incoming lines which appear multiplied upon a given group oi first line finders such as the one shown in Fig. 1. Relay 122 closes a clrcuit over the sequence switch springs through the interrupter brush 136 will be open, and the shunt being removed from around the power control test relay 137, such relay will be energized, opening the circuit of the power magnet 123 and closing the circuit of the holding magnet 138 over the springs 105 top and 107, thereby positively stopping the brush carriage in proper posi- 5 tion. The energization of the relay 137 has also driven the sequence switch 100 out of its first into its second position. In this n'lovcment of the sequence switch a test guard is maintained upon the terminal 132 and the seized line through the spring 11.2 bottom, the spring 102 bottom being opened as the sequence switch leaves its first position. In the second position the spring being closed, the ut-ofi' relay 139 of the calling line is energized, causing the dei ncrgization of the line relay 121 and the consequent deenergization of the pilot relay 122, provided no other lineot' this group is at this time calling and not as yet been seized by a line finder. The deenergization of the relay 121 opens the battery circuit to the terminals 132, and the line now having been seized and being maintained busy, no selectable potential is possible upon its test terminal 132. The sequence switch 1009011 coming into its second position, has established a circuit 1.01 and'103 tor the power magnet 123 of all spring 02 bottom, back contact of relay 237 11d spring" 03 top tor the, pow magnets 320 of the idlc second line linden in which the circuit. connected to the first line finder snown. appears in multiple. The brush carriages of such idle line finders, thcrcfoir, move the brushes 2 8, 22-0, 2 -30 over the contacts 231, 23 3.34 of the various line s p-caring: in such line finders. The. scqurncc switch 100, on coming, into its second position, by closing ihcsprings 108 bottom. 106 top and 107, has placed selectable. potential on the. terminal 22-3 of the trunk lino or circuit connected to the first line iimlcr associated with such sequence switch 3.00. ii "hen the. brush 230 of one of such second lino finders comes in contact with the terminal 554-, upon which this selectable potential e ists, the test relay 2.35 will be energized, the circuit for such relay including the springs 30- top, 05 top and either the interrupter brush 250 or the spring 606 top. Such relay will, there fore, be energized, closing in parallel to its right-hand winding the low resistance holdinf: winding, which will so reduce the poten tial upon the terminal 234 that no other sec-- oiul line tinder can now seize tho line to which such terminal is individual. The brushes of the scizint second line finder, llliWGVQl'. will continue to more until when they arc centered upon the terminals of the seized 1w. the circuit over the interrupter brush is opened, and. the shunt being there by removed from around the power-control test rclay 223. such relay is energised to stop the switch in the usual manner by opening tho circuit of the power magnet 224' and closing the circuit of the holding n'iagnct 235 at the same time driving the sequence switch 000 out of its first into its second I sition by closing: a circuit over tho spring (it)? top. As the. sequence, switch .300 learns its first position, and until. it has passed through its seventh position, a busy test guard. is maintained upon the terminal 33% by the closurc of the spring 010, connecting ground to such terminal.

As the sequence switch 600 was passii'ig from its first into its second position, the. spring (311 was closed suliiciently long to drive the sequcnce switch 200 out of its first position, the circuit for moving such sequence switch including the spring 202 bot tom. This sequence swit ,-.h comes to rest in its sccond position. in position 2 of the sequence. switch 600. and in position 2 of the sequence switch 200, the selection of an idle registering and controlling mechanism will take place. Bcforc considering this operation, however. the various effects of the seizure of the circuit connected to the first line, finder; and the nimement of the sequence switch 200 into position 2 will be considered. When the test rcla y 235 was 6H6!- giz'cd, the circuit therefor also included the relay 1.37, to maintain it energized, and re lay 13? being energized the sequence switch 100 is-Inovcd from its second position to its fifth position. in position 5 the circuit for relay 137 will include the resistance 140 as well as the resistance 141, but suchrel'ay will be maintained energized so long as the spring 610 top is closed. In position 5 of the sequence switch .100, the spring 110 being open, the circuit for the cut-off relay 139 now includes the spring 102, the relay 135 and the spring 207, the sequence switch. 200 now beingiin' the second position. in this position also the spring 112, is open-and the circuit of the calling line. is extended over the springs 210 top and 211 top to the repeating coi'l 239. 600 came into its second position, the springs 604 bottom, 639 top, 605 bottom, iilliibOttOIH and 013 bottom were closed. If at this time the sequence switch 700 individual to the connecting circuit shown is in such position that an idle registering and controlling equipment connected. by it to the leads shown, the. relay 1240 will be, energized over a circuit .cl'uding springs 703, 619 bottom, 704c'rclay i ii and spring 405 of the sequence switch 400 ing' and -ntrolling equipment. ever, a epinent with which the leads are connected over such sequence switch. 700 is already .a ..y, the test circuit including the relay of some other connecting circuit will already be energized over the circuit including the relay 4% and insutlicicnt cur- "ol through the relay 2&0 shown, to energize it. A circuit will, therefore, be established over the baclc contact of such relay E240, spring (312-5 bottom and spring 702 to cause the sequence switch 700 to move and it will continue in motion until on closing the circuit from the leads of the conwillihc opened and the relay 237 being energized in parallel with the relay 220 the sequence switch 600 will be driven through sequence switch springs 602 top and (507 top from its second into its ,third position. In this position the relay 240 and the relay 237 are directly connected over the spring (519 bottom and over the spring 704- hottoni, for example as shown, to the starting relay 426. This idle registering and controlling equipment is now seized and is inaccessible to any other connecting circuit having access thereto until it has performed its function or has been released by the hanging ,up of the receiver of the calling subscriber, as will be hereinafter described. As the sequence 1 switch 600 moved into its third position it closed the circuit over the spring 609 to drive the sequence switch 200 also to its third posltion. In this position springs 210 As the sequence switch bottom and 211 bottom are closed, and the impulse receiving circuit from the subscribers substation to the registering and controlling equipment is now complete, such circuit being traceable from battery througl'i brush 126 and" terminal 130 of the first line finder switch over the subscribers line and through his substation, terminal 129 and brush 125 of the first line finder switch, terminal'231 and brush'227 of the second line finder switch, spring 211 bottom to ground and back to battery. This circuit being established, and the relay 426 being energized, as before described the sequence switch 400 is driven out of its first and into its fourth position. It will be observed that the calling .subscribers supervisory relay 241, which at this time controls rest-oration and which in position 2 and position 4 and positions subsequent thereto is directly uuder the control of the calling subscriber, is energized by the closure of a spring 205. The apparatus will now await the sending of impulses by the calling subscriber, such .im'pulses being arranged in groups corresponding to the complement of the digits of the numerical designation of the called. subscribers station that is to say, the called subscribers numher being assumed to be 307, thecalling subscriber will transmit to the central station three series of impulses, the first series comprising seven impulses, the second series comprising ten impulses, and the third series comprising three impulses. In each of these series of impulses the last impulse sent will be relatively longer than the other impulses of the series, which other impulses are, in fact, quite short. The sender by which these impulses are sent may be, oi any desired structural character, provided that the impulses are sent in a complementary manner, and that the last of each oi. the groups of impulses sent by such device is relatively longer than the other impulses of such group. A sender is diagrammatically shown capable of accomplishing the necessary fund tions, and in which the setting of the sender produces no impulse in the circuit. The

' impulses as produced in the system as disclosed are interruptions of the circuit.

The system herein disclosed is for clearness shown only as a 1000 line system. In such a system there willbe five groups of final selectors, each accessible to 200 lines thereof, and the group selectors used will have only five of the ten banks thereof utilized, one bank of contacts being connected tot-he trunk lines of the group of final selectors individual to one group of 200 lines, another connected to anothergroup of final selectors individual to another 200 lines, and so on. In accord ance with the translating system disclosed herein, the selection in the group selector of the trunk line leading to the group of lines having the proper hundreds digit is such that if the 100s digit of the desired line is zero or one, the tripping spindle of the group selector will be adjusted to release the proper set of brushes on the brush carriage by the movement of such spindle one step or stage. If the 100s digit of the desired line is two or three, such spindle will be moved three stepsor stages. If the 100s digit is.four or five, the spindle will be movedlfive steps or stages. If the 100s digit is six or seven, such spindle will be moved seven steps or stages, and finally if the 100s digit is eight or nine, such spindle will be moved. nine steps or stages. Of course, it will be understood that if the sys 'tem is for more than 1000 lines that the intermediate steps or stages, that is, second, fourth, sixth, eighth and tenth will be reserved for' use when a trunk line is desired leading to the groups of selectors having access to the lines of such second thousand. In a. 1000 line system as herein disclosed, the trunk lines may be, and it will be assumed, are, connected to the alternate levels of contacts in such group selector. It will be further understood that by properly rearranging the tripping teeth. upon the trippingspindle, the live levels and terminals which are usedmay be. arranged, if desired, adj-accntly to each other, so that the first level will. be selected by a single step of the tripping spindle, the second level by three steps oi such. spindle,the third level by five steps of such spindle, and so 011.. Furthermore, if

by one step of the tripping spindle of the 1 group selector, a line whose 100s' digit is 1 by two steps of the tripping spindle, and so on. As shown, however, the arrangement of the lines and the selection in the roup selector will take place as first above escrlbed. An operation, therefore, of the subscribers sending mechanism to send the 100s digit 3 will produce seven. breaks in the circuit, hereinbefore described, including the step- ,ping relay 427, the last of such breaks being relatively longer than the others of the group. Upon the initial energization of the stepping relay 427 a circuit was closed by its armature over the spring 408 and the back contact of the changeover relay 428, including the lower winding of the 100s reg ister 4:29. This causes the energiz'ation of the power magnet of such register and 1t moybs until whbn midway between its zero or normal position and its first position, its

through #botlrof said windings, or when there is a'. circuit through neither of said' windings, such regis er will stop; whereas, when a'circuit is closed through but one of said windings the register will move. The register 429, having therefore been brought to rest between its zero and first positions, will await the opening of the circuit throughi its lowerwindlng at the front contact of the stepping relay 127 before moving further. Therefore, as the result of the first impulse or interruption in the circuit in the operation of the subscribers sending mechanism, and the consequent deiinergization of the stepping relay 427, the register will move into its first position, the circuit of the upper winding thererf being closed through the positioning spring 4:71. Upon the cessation of the first impulse, the relay 427 is again energized, and the register 429 is driven toa position intermediate of its first and second positions. correspondingly in response to the second impulse it will be driven into its second position. Therefore, as seven impulses are being received, the seventh impulse will drive the register 429 into its seventh position. As this impulse isa longer one the stepping relay 427 will be deiinergized sutliciently long for its armature to close at its back contact and spring 413 a. circuit for the slow operating changeover relay 4% and energize the same. This changeover relay opens the circuit of the register +29 at its right-hand armature, in order to prevent any false operation of such register, and closes at its left-hand armature a circuit over spring 404 for the sequence switch 400, driving such sequence switch into its 0th position. The 100s register has now been set. and it may proceed to control selection in the group selector. For this pun pose-the outgoing sequence switch 450 shown to the right of Fig. 4, and whose springs are all to the right of the dotted line, has been started by the closure of :the spring 407 bottom as the incoming sequence switch 400 passes through its 5th position. Before, however. describing the selection controlling operation initiated by the movement of the outgoing sequence switch 450. further registering operations will be described. Upon the rei' stablishment of the transmitting ciruit. and the consequent energization of the stepping relay 427, the circuit through the 1,151gss1 controlling position, the 10s register 4-30 thereby being removed from association with the stepping relay, and the units register 431 being placed under the control of such relay by the closure of the spring 405) bottom. The closure of the controlling circuit including the stepping relay 427 and its interruption three times to send the digit 7 will cause the units register 431 to move into its third. position inthe.

manner now well understood, and the final impulse being a long one, the sequence switch 400 will be driven out of its eighth position by the energization of the changeover relay 4-28. switch 400 will remain until at the conclusion of the selection controlling operation it is started in motion to its normal position by a. circuit closed by the outgoing sequence switch $50 in returning tonormal over the spring 407 top. The registers have now been set to properly control the/selection controlling operations in accordance with the numerical designation of the desired subscribers line; the 100s register has been moved In its ninth position the incoming loo into its' seventh position, the 10s register" has been moved to its tenth position and the units register moved into it third position. As the in coming sequence switch 400 reached its ninth position a circuit was closed over the spring 42, and the spring QOlS bottom, to drive the sequence switch 200 out of its third into its fourth position, in which position the supervisory relay 2:41 again placed under the control ofthe calling subscriber, and thesending circuit from the calling substation is open at the springs'210 bottom and 211 bottom. The outgoing sequencetswitch' 4 50 of the registering and equipment, when it was moved from its first position as the incoming sequence switch 400 passed through its fifth position as above described, continued in motion until it reached its fourth position. In passing determine whether the s digit of the number registered was odd or even; it hav ing been foundto be odd, the hundreds register is in its seventh position, seven impulses having been sent by the calling subscriber operating his sending mechanism for the digit 3, a circuit \HS closed for the translating relay i312. It will be observed that the from its first to its second posi- .tion, a test was made by the spring 41 to spring 474 of the 100s register is closed in the following positions; only a few of which, for clearness, are indicated. upon the clrawings:

The relay was therefore energized, closing by its right-hand armature a locking circuit'for itself including the spring top, and such relay will be maintained energized until the sequence switch leaves its ninth posit-ion. As the sequence switch 450 passes through its second position the closure and subsequent opening of the circuit of the power magnet of the 100s register over the spring e58 bottom "will drive such. register one additional position that is in this case into its eighth position. Also the sequence switch 4-50 passes through its third position the translating relay being locked up circuit will he established over the spring 4:60 top, left hand armature of such relay and. spring e61 bottom, to drive the 100s register from its eighth'into its ninth position. 011 coming into its fourth position the sequence switch 600 be ing already in its third position, the fundamental circuit from the registering and controlling equipment is closed to the group selector shown on Fig. 2. Th'is circuit includes the line relay 242 of the group selector, and the select-ion controlling stepping relay of said equipment, both of which relays will he energized. This circuit also includes the springs 612, i723, 457 and 611 bottom. The energization of the relay 24 2 drives the sequence switclflSOO into its fourthpositi'on over the spring (ll-1;, in which position the circuit for the tripping spindle power magnet 24.3 is closed and the tripping spindle starts in motion. In moving from position position 1 seitpience switch 600 makes no changes in the fundamental circuit. As the relay 433 was energized coincidently with the energization of the line relay 242, it closed the circuit over the spring 458 top for the loWer winding of the-100% register 429; the register, therefore, nioved a half of a position, that is, until the closure of the circuit through its npper'winrling and a the positioning spring 4:71 thereof is closed. As the tripping spindle of the group selector began to move it intermittently closecl a circuit to ground, such circuit being so connected to the fundamental circuit that when it, is closed the relay will be shunted and (le'e'nergizecl, though the line relay 94-2 is maintained energized. This deenergiaation of the relay 433 will take place once for each nioveinent'ot' the tripping spinclle one step I. I" 101 the tripping spine or stage. Upon the clenergization of the relay the 100's register again moves until it comes into its tenth. position, iron). which position it will be moved to a position intermediate its tenth and eleventh p0sitions, when the relay is again energized. as the-tripping spindle comes into its set p0- sitionto trip the first set of brushes of th group selector; in the continued motion of the tripping spindle a second deiinergization of the relay 33 takes place and the. lOOs register moved into its 11th position, to he moved again into a. nosition intermediate between its eleventh anti Zero positions, when the shunt is again reinovetl at the tripping spindle. The next closure the earth connection at the tripping spindle, and the consequent third-riei ner ization of the relay drives the 100s iter into its zero or normal iiosition. thi osi'tion the U3 is open and. onseqi t y, not only will the relay 433 remain a" i when the connection to earth is hro spindle, but also the line r ay EH2- Will be cleiinergized, both the to; uinental circ being open. As soon this occurs, the circuit.

i open at the front conm i and the trippii Such tripping L three storm or stages, isnow tion to release the third set of brushes on the brush carriage of the group rtor, as recalled that a trunk line lea-cling to the group of final selectors in which the desired line appears is to be found in the third bank or level of such group selector.

- As the 100's re ter came into its zero ornorinal position, it the it mining sequence switclwiOO is in its 9th pos tion--that is, it 10s and. units registration is complete--21 circuit wiil he cioseii including the springs 56, -772 and 4-10 to drive me ting sequence switch 45-? into its Gt i which it is ready to control te soon. as an idle trunk line a proper final selector has been tamsl and. seiseil in the group selector, will be described. It the incoming sequence switc 3, 4:00 is notes yet in its 9th position, the outgoing sequence switch 450 will remain its .tth position, moving into itsfith pUSlhlC'l'l as soon as the sequence switch 400 reaches its 9th position.

When the line relay i249. stopped the move ment' of the tripping; spindle of the group selector, it also ch std a circuit over its back contact 21316 tis spring 602 to back contact and armature of the relay ','Wl1ici1 is deenergized after the sequence switch 600 left its 3rd position, {uni spring 607 bottom, to drive the sequence switch 600 into its -5th position. In the 5th position a circuit will he established for the group selector power magnet M4, including the spring 603 hothen at the tripping v tom, the back Contact and armature of relay 237, sequence switch spring 602 top. and the back contact and armature of the line relay 24:2. The brush carriage of the group selector, therefore, will begin to move in its movement. causin the proper set of brushes to be released in the movement past the said tripping spindle and then causing such. re" leased brushes-2&5, 246 and 247 to make-coutact with the various sets of contacts in the selected level. So long as the test brush makes contact With the test terminals of trunk lines which are already engaged, insuiiicient potential Will'be found thereon to energize the relay due to the fact that the low resistance Winding of a relay correspondingto the relay 2 35 of some other group selector is alreadv connected to the terminal multiplied to such test terminal. As soon, however. as the brushes come in contact with a set of terminals individual to an idle trunk line, full potential will be found on the test tern'iiual thereof. and a circuit will be established for the test relay 235 extending from battery at final selector over the spring 312 bottom, spring 314 top, the left winding of the relay 331, test conductor of the seized trunk line. test brush 24'. of the group selector, right-hand high resistance winding; of the test relay 235, spring; 605 top, power control test relay and spring 606 top to ground. The test relay 2.? will be energized but the relay 237 will not be energized owing to the shunt therearound existing over the interrupter brush lhe energization of the relay closes a low resistance circuit through its left-hand Winding parallel to its rightdiand winding, which so reduces the potential upon the test terminal of the trunk line that the test relay of no other group selector, the brushes of which come in contact with the terminals of such line, will be energized. As soon as the brush carriage, which is continued in motion, properly centers the brushes upon the terminals of the seized line, the shunt circuit through the interrupter brush Will be open and the relay 237 will be energized. The energization of this relay will open the circuit for the power magnet- 244 and close the circuitfor the holding magnet 250 over the springs 608 top and 607 top, so that the brush carriage of the group selector will "be properly and accurately stopped in the well-knownmanner. The energization of the relay 237 has also closed I a'circuit for the sequence switch 600 to drive such sequence switch into its 6th position. In this position of the sequence switch 600 the fundamental circuit is connected through from the final selector to the registering and controlling equipment, and the closure of this circuit at this time depends upon Whether the outgoing sequence switch 450 has reached its 6th position. When the sequence switch 450 was driven out of its fourth. position upon the completion of the hundreds selection controlling; operation it moved directly into its sixth position but in passing through its fifth position the moinentary closure of the spring 462 bottom has driven the tens register into its eleventh position in the now wellauiderstood manner. When new the funilaniental circuit is again closed in the sixth position of the sequence 'magnet 333 is closed over the spring; 809.

bottom and the front contact of the relay 332. The tripping spindle will thereupon begin to move. The energization at this time of the relay 433 has closed a circuit over the spring; an top to move the tens register onehalf of a. position from the position in which it was set as described.

it will be recalled that the 105 digit of the desired line zero and, therefore. such line is to be found in the first bank or level of the final selector. It will therefore be necessary that'the selection controlling operation of the final selector should be tor-- initiated when the tripping: spindle has moved one step or stage and is in position to release the set of brushes corresponding to the first bank set or level oi contacts. it will also be recalled that the tens register Wasset by the subscriber in its 10th position and subsequently moved to its eleventh position. lVhen. therefore, the tripping spindle at the final selector moves its first stepfjor stage. the shunting of the relay 433 in the Well-known manner drives the tens register. into its zero on noi'inalposition. This movethe fundamental circuit at the spring 483 of such register, so that when the shunt circuit through the tripping spindle is opened both the relay 433 and the relay are deenergized. At the same tiinethe closing of the spring 482 of the tens register closed a cir cuit including the springs 411. 482 and 463' top to drive theyout-going sequence switch 450 into its 8th position -readyto control .ment of the tens register immediately opens deenergization of the line relay 332 as just described the movement of the tripping seventh position upon the termination of tens selection the momentary closure of the spring it). moves the units register one midi-- tional position so that w zen the sequence switch stops in its eighth position and again closes the fundamental circuit the units register is in its fourth'position. The closure at this time of the fundamental circuit again energizes the relays and 433, but this time in the 4th position of the sequence switch 300 end the 8th position of the sequence switch 450. In the sith position of the sequence switch 300 the energizetion of the relay 332 closes at circuit over the scoring 306 top from the brush carriage power magnet of the final selector, and such brush can riage begins to move. In the initial move ment of the brush carriage, the proper set of brushes (in this case the first set} is tripped as the carriage passes the tripping spindle. In the subsequent movement of the brush carriage the brushes 334;, 336 sweep over the sets of terminals individual to the lines niultipled to this hunk or level of contacts. For each movement of such brushes to a set of terminals the interrupter device 337 closes a circuit to ground from the fundamental circuit over the springs 313 top and 315 in the well-lmown manner, such circuit to ground as is well understood shunting the relay while maintaining the relay 332 energized. Upon the energization of the relay and its subsequent intermittent denergzizotion due to the shunt inc; action of the contacts of the interrupter 337 at the final selector, the units register will he stepped in the well understood man nor, one full position for each energizetion and subsequent deiinergizetion of the relay 433. At the end of eight of such operations of the relay the units register will enjoin be in its normal position, the selected brushes of the final selector at this time being; shout to make contact with the 8th or No. 7 set contacts of the bank or level to which they are individual. It will be recalled, however, that since the desired line locuteo in an. odd hundred, the particular line desired is to be found in the second half of the fi cl selector, and it is therefore if .ry that the selecting operation should not terminate at this time; For thieirezison the fundamental circuit is not opened at this time at the spring 4923 as would be otherwise the case,-

a shunt being maintained about such spring, such shunt including;- the springi-(SO bottom, let" hand armature of the trunsiuting relay i 11 owl the spring l'iil' top.

It 'will be recalled that the relay 432 was locked up when the sequence switch 450, in passing from its first to its second position, tested the condition of the 100s register e29, and on finding it in a position corresponding to an odd hundred, completed the circuit for the translating relay The fundamental circuit not being open at this time, the brush carriage at the final selector will continue to moveuntil the units 1e ister -l3l has made a complete revolution as a result of such movement. register will take twelve additional steps. It will now be seen for what purpose the two additional notches in the interrupter plate of the final selector are provided, as hereinbefore described. To reach the contacts of the desired line after the units register has first reached its normal position would otherwise produce only ten denerg'izations of the stepping relay 433, and,

This means that the unitsconsequently, only ten steps by the units register. Since it is necessary that the llllltS register should come into its zero or normal position in order to cause the cessation of selection, it is necessary that two additional steps be provided for and, consequently, two additional notches are cut in the interrupter plate of the final selector to produce such steps. Therefore, after the stepping relay 4.33 has been operated twelve 'additional times, and us the selected brushes of the final selector ere coming into contact with the 'ith set of terminals in. the second half or range of the selected bank or level of the final selector, the units register will again be in its normal position. As the units register passed its normal position Without stopping, as above described, circuit was closed by r'he spring 492 over the spring 463 bottom to drive the sequence switch 450 out of its 8th endinto its 10th position, this circuit being only maintained momentarily by the spring 49 The sequence switch stopped in its 10th position. When now the units register i231 comes a. second time into spring 493 thereof being opened at the springs M50 bottom and 461 top, the fundamental circuit is immediately opened, producing the deenergizatiomiu the'manner Well understood. of the

relays

332 and 433 to terminate selection in the final selector. The un s register 431 coming into its normal position again closes the spring 4 92, and the sequence switch 450 returns to its nor-. mail position, in which movement in passing through position 11 it closes a circuit at spring bottom to return the sequence switch 400 to its normal position. It should be also noted that the sequence switch 450, on leaving its 9th position, opened the looking circuit of the translating relay 432. The desired line now having been selected, the services of the registering and controlling spring 314 top.

equipment are no longer required for this connection, and, therefore, as the sequence switch 400 left its 9th position the spring 406 opened the circuit for the relays 1126 and 240, which circuit had been substituted for the one originally established over the spring r05 as the sequence switch 400 left its first position. The relays 426 and 240 are therefore deenergized. The ene. ization of the relay 426, and the restoration of the sequence switch 400 to normal will :ause the registering and controlling equipment shown on Fig. 4 to test. idle and agiiessible to any connecting circuit taken for use which has access to' it. At the same time that the relay 426 is deiinergized the relay 24:0 was de'nergized and by the retraction of its armatureclosed a circuit to drive the sequence switch 600 from its sixth'into its seventh position.

In this movement, however, the contact 611 top is closed and the sequence switch 200 is 'driven from its fourth into its fifth positionf In these positions the sequence switches-(300 and 200 await the further operations of the final selector apparatus shown on Fig. 3.

energized, and cltmed for itself a circuit to take the place of the circuit through the spring 312 bottom, which is opened as the sequence switch 300 leaves its first position. As the sequence switch moves from its fourth to its fifth position, the-spring 314 .top is opened and 314 bottom is closed. The

relay 331 is maintained energized. both of its windings nowbeing included in the circuit and the battery is connected over the spring 314 bottom to the power control test relay 339. At the same time the spring 307 top is closed, connecting battery with a "high resistance winding of the test relay 349. The fifth position of the sequence switch 300 is the testing position thereof. If in this positipn full potential is found upon the test terminal 342 of the desired line, indicating that the line is idle, the test relay 3%!) will be energized-over its right hand high resistance winding. If on the other hand the normal potential 'upon such test terminal is reduced by such line being busy. either as a calling line or a called line. as will occur in the well-known manner. the test relay 349 will not be energized. Assuming first that the line is idle and that such relay is conscqucntly energized. it closes over its armature a circuit, through its low resistance left This is the through or talking position of this sequence sw1tch.

This relay was therefore.

into its eighth position.

- hand winding and the test relay 339, in parallel to its right hand winding, which will so reduce the potential of the test terminal of such seized line that it will test busy in all other final selectors in which it appears. Such circuit will also energize the relay 339 and when the sequence switch 2300, comes into the sixth position, it will find circuits closed, one over the spring 317 and the other over the spring 305 bottom, and the front contact of relay 339 and the back contact of relay 332, to move it into its tenth position, in which position, and also in the eleventh position a circuit will be found closed to move it into its twelfth position. The sixth position of this sequence switch is provided for hunting an idle line to aprivate branch exchange, in case the particular line selected is found busy. The apparatus for performing this operation is not shown, however, and in order to drive the sequence switch through its siXth position, which is, as" shown, an idle position, whether the desired line is found idle or busy, the spring 317 is provided. 'The twelfth position of the sequence switch 300 is the ringing position. in this position ringing current is projected over the called line by the closure of the springs 310 bottom and31-1 bottom. As the sequence switch 300 passed through its eighth position, the trunk line leading to its final selector was shortcircuited by the closure of the spring 309 bottom. This causes the momentary energization of the supervisory relay 248, which by the attraction of its armature drives the sequence switch200 This would cause the subscriber to receive the busy tone by the closure of the springs 212 bottom and 213 top. except for the fact that almost immediately after as the sequence switch 300 passes from its eleventh into its twelfth position, the spring 30!) bottom is again closed energizing the relay 248 to drive the sequence switch 200 into its eleventh position. in this position of the sequence switch 200, the springs 212 top and 213 bottom being closed. the subscriber receives the distinctive ringing tone, and will continue'to re-' ceive such tone so long as the sequence switch 300 remains in its twelfth position. long as the called subscriber does not respond, insufficient current will pass over the ringing relay 343 to energize it'. As soon. however, as the path for direct current is closed at the subscrihers substation, bythe removal of his receiver fromits switch hook, the relay 343 will be energized and drive the sequence switch 300 into its thirteenth position. In this position the circuit is closed through from the battery and repeating coil shown in Fig. 2 to the called subs'cribefs substation, and the relay 248 is therefore energized. driving the sequence switch 200 out of its eleventh and into its fourteenth position. The sequeiice switch 100 being in its fifth position,'the sequence switch 200 being in its fourteenth position, the sequence switch 600 being in its seventh'position, and

the sequence switch 300 being in its thir 'teenth position,the calling subscriber and, the called subscriber are now connected, each subscriber being supplied with transmitter current from the battery; shown in connection with the repeating coil Conversation may now take place. v

- Disconnection ellpon the termination of conversation, one or both subscribers return their receivers their respective switch 15 hooks, thereby opening a circuit over which the supervisoryrelays 241 and'248. are maintained energized. Assuming that the called subscriber first restored his receiver to' its switch hook, the deenergization of the relay 248 closes a circuit over the

spring

203 and 209 bottom, todrive the sequence switch 600' out of its seventh position and intoits eighteenth position. In this movement the sequence switch 600 closed in its 8th position a circuit over thesprings 609 and 202 top, to drive the sequence switch QOO baCkfO its normal position. On coming into its 18th position the sequence switch 1600 established the usual restoring circuit for the brush carriage of the group selector, and such brush carriage moves until the brush 244 of the interrupter comes in contact with the normal segment, at which time circuit is closed. over the spring 618 to energize the relay 237 which'stops the movement of the brush carriage in the usual manner and drives thesethis relay'is again established, provided the calling subscriber has not restored his receiver to its switch hook, which includes the spring 108 bottom, the spring 111, the-substation circuit and the spring 112 top; The sequence switch 100 wiil'therefore stop in its 9th position and remain there until the subscriber opens the circuit to direct current at his substation by replacing his receiver upon its switch hook. As soon as this occurs, the relay 137 will again be denergized and drive the sequence switch 100 be oh: to its first or normal position. It will be observed that the cut-0H; relay 139 is controlled through the 7th position by a circuit including the spring 102 top. and in the 8th or 9th position by acircuit including the resistance 199 and the spring 110. This transfer of control. is accomplished before the circuit of the cutoff relay 139 was opened at the spring 207. As the sequence switch 600 left its 7th posise ector. This relay therefore immediately tjion, it opened at the springs 605 top and to the circuit for the relay 331 at the finalallowed its armatures 'to ,retract, its left hand armature closing a circuit 'over the spring 308 bottom to energize the line relay The energization of this relay drives tion into its 16th position.- On coming into 'itsi 16th position, the circuit at the called subscribers substation being already opened, the relay 332 is Without current and therefore is denergized, driving the sequence switch 300 into its-18th position. In this posit-ion of the sequence switch 300 the usual circuits are established to restore the switch carriage of the final selector. to normal.

lay 331 controls through its right-hand armature the energizing current for itseliin the sequence switch 300 out of its'13th posi'- 4 all positions, except position 1, of the sef quence switch 300. However, in ositions 8 to 17 a testguard is maintaine terminal of the trunk line by the closure of the spring 610 bottom. Assuming-.thatthe calling subscriber first restored h s receiver to its switch hook, th'e restoration tb normal of the group selector apparatus, the sequence switch. 600," sequence switch 200 and the line finder apparatus, willv take place precisely as has been hereinbefore described, ex cept that'these operations are initiated by the denergization of the supervisory relay 241 instead of by the deenergization of the supervisory relay248, as has been described,

with the further exception that the sequence 1 switch will not stop in its 9th position as the circuit for the relay 137 over the calling subscribers line willznot be established. At the filial selector, however, when the se-- quence switch 300 comes into its 15th and 16th positions the called subscriber not as yet having restored his receiver toi ts switch hook, a circuit will be established for the relay 332, including the springs 308 top, 310.

top, subscribers line, 311 top and 309 top.,

on the lot Therefore, when the sequence. switch 300 mes into its 16th position it will'there stop and await the restoration of the called subscribers receiver-to its switch hook, which, when it occurs, will open the circuit to the relay 332, all-owing such-relay to-deenergize,

to drive the sequenceswitch 300 .out of its 16th position, after which the restoration of.

' throu 11 its Sthposition', it will bc iecalled that t e closure of the spring 369 bottom the final selector apparatus will take place as has been hereinbefore described. v

Attempted connection to a busy Zine-If after the final selector switch has been moved to bring its

brushes

33 i, 335, 336 intov contact with the terminals of the desirerlline, and the sequence switch 300 is -moving through its5th and 6th positions, such line should be found busy, insufiicient potential will exist upon the test terminal 342 to accomplish the energizationof the relay 34:9, consequently, no energization of the relay 339 will take place and when the sequence switch 300 comes into its lOth position it will stop, and the restoration of the brush carriage of the selector 'Will take place over a circuit including the armatureand back contact of the relay 332, armature and back. contact of the relay 339, and spring 306 bottom. As the sequence switch 300 passed caused the energization of the supervisory relay 248130 drive the sequence switch 200 into its 8th position. In this position the busy tone is applied to the trunk line and the calling subscriber is thus notified of the busy condition of the desired line. When its the brush carriage of the finalselector reaches its normal position the relay 332 will be energized by circuit including the normal segment of the interrupter 337, and the sequence switch 300 will be driven into its 11th position. The circuit for such relay 332 being opened at the spring 313 as the sequence switch leaves its 10th position, .the sequence switch 300 will stop in its 11th position. This sequence switch will remain .in this position and the sequence switches 600 and 200 will remain in their 7th and scribers line being entirely unaffected) until the calling subscriber restores his receiver to its switch hook when in response to the'de energization of thesiipervisory relay 241 the sequence switch 200 will'be driven from its 8th into its 11th position. As it comes into its 9th position circuit will be established over the back contact of the supervisory relay.'and' the spring 209 bottom, to drive the sequence switch (300 out of its 7th position, from which position the restoration of the group selector switch. the sequence switch (300, the sequence switch 200 and the apparatus of the first finder will take place precisely as has been hcreinbctore described.

.I m'thermore. the restoration of the final selector apparatus will also take'place as hereinbetore described iimnediately that the relav 331 is dei nergizcd as the sequence switch (300 leaves its 7th position.

'lrmnufiurc dlrhLU'll'II(5(7i7:())'1..?If the calling subscriber should restore his receiver to its switch hook in the third position of the sequence switch 200, the dci nergization of the stepping relay will cause the energization of the change-over relay F28, and the 'relay 427.1'emaining deenergized and the relay 428 energized, the incoming sequence switch 400 will be driven directly into its ninth position, from whatever position it maybe at the time. When sequence switch lOO reaches .its ninth position, the sequence switch 200 will be driven from its third into its fourth position as has been hereinbet'ore described.

The sequence switch 200 will then be further driveninto its eleventh position by the closure of a circuit over the back contact of the supervisory relay 241,- and from such the receiver to its switch hook at any time after the sequence switch 200 has left its third position and before it comes into its eighth position, the de'nergization of the supervisory relay 241 will drive the sequence switch 200 into its eleventh position from which the restoration of all the apparatus will take place as hereinbefore described, On any occasion of premature disconnection which takes-place when the registering controlling apparatus is in an off-normal condition, the deenergization of the starting relay 426 will insure the restoration to normal of the various registers of the registering and controlling equipment. The deenergization fora prolonged period of the stepping relay 427 causes the change over relay 428 to beenergized sufficiently long to drive the sequence switch 400 into its ninth position, In passing through itsfifth position, the sequence switch 450 is started in motion as hereinbefore described. 011 coming into its fourth position. it it is not already in this position, the-starting relay 426 being now dei nergized, a circuit is established for the stepping relay 433 which includes the back contact and left hand armature oi the starting relay, spring 473 of the'humlreds registcnspring 457 and back contact and right armature of the-starting relay +26. The stepping relay "433' being energized a circuit is closed'through the lower winding oi the power'niagnet oi the hundreds register and the register will start in motion. It will be observed that the circuit through the spring 471 and the upper winding of the power magnet m the hundreds register is