US1107148A - Telephone-exchange system. - Google Patents

Description

E. E. CLEMENT. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED AUG. 1I 1 906,

9 SHBETSQSHEET 1.

' E. E CLEMENT. TELEPHONE EXCHANGE SYSTEM. APPQl- ICATIONTILED AUG. 1, 1906.

Patented Aug. 11,1914

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APPLICATION FILED AUG.1, 1906.

Patented Augull, 1914.

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B. E. CLEMENT. TELEPHONE EXGHANGE SYSTEM APPLICATION FILED AUG. 1, 19 06.

- Patented Aug. 11,1914.

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CLEMENT. TELEPHONE EXCHANGE SYSTEM.

APPLICATION? FILED AUG l, 1906.

lwenioz E. E. CLEMENT. TELEPHONE EXCHANGE SYSTEM. {.FPLIGATION FILED AUG Patented-Aug. 11, 191

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Ewento'a 6 av b 0 t 1 E. E. CLEMENT. TELEPHONE EXCHANGE SYSTEM. 'APPLIQATIW FILED AUG. 1, 1906. Llgalzgfi Patented Aug. 11, 191i Q-SEEETS-SHEET 7.

E. E GLEMENTJ TELEPHONE EXCHANGE SYSTEM.

' A LIQA' QN FILED 11119.1, 190s. 1,107,14a.

Patented mg. 11, 1914,

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TELEPHONE EXCHANGE SYSTEM. APPLIGATIONTILED AUGJ, 1906 1,107,148. I Patented Aug.11,1914.

9 SHEETSSHBET 9- witnesses UNITED STATES PATENT orrron.

nnwann n. CLEMENT, or WASHINGTON, DISTRICT. or COLUMBIA, ASSIGNOR, BY

MESNE ASSIGNMENTS, To FREDERICK c. STEVENS, or a'TTIcA, N W YORK.

TELEPHONE EXQHANGE SYSTEM.

have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a specification, reference being had therein to the accompanying drawing. 4 r

My invention relates to telephone ex change systems and has for ,its object the production of such a syste "in which the calls originating at subserib rs stations are distributed among connective terminals such as operators plugs, in an improved manner.

Briefly stated, my invention comprises connective apparatus, which may be either manual erautomatic as regards the calling part thereof, and which is provided with what I have called relay primary selectors, as described in the above mentioned applica- 'tion, for the purpose of answering incoming calls and connecting the calling lines to idle trunks or connective circuits. These relays are arranged so that they bear a decimal relation to each other and to the lines, and they are positive in their action, being controlled by the calling lines themselves.

In'operation,when a line calls, its line relay pulls up,-closing the circuit of the appropriate tens and units relays of that hundrcds group to which the calling line helongs, and these two relays in pulling up connect the line onto the trunk with which they are associated. Such connection being complete, the conditions are the same as if an operator had manually inserted a plug into the ordinary answering'jackof the calling line; and the sleeve or other relays of the trunk, as well as the cut-ofi' relay of the line, immediately take current and perform their usual functions. The primary selector relays are self-locking, and the locking circuit for each trunk group is controlled by one of the distinctive trunk relays which responds to acts of the subscriber, whereby at the conclusion of the"COI'IYQI'SiLllOll, when the subscriber hangs ,up his receiver, the locking circuit is broken and the primary selector relays let go, discoi'lnecting the line from the trunk in the same manner as if an operator had pulled out an answering plug which had previously been inserted.

In. the present application I have specifically illustrated, "and shall hereinafter spe- Specification. of Letters Patent.

Patented Aug. 11, 1914.

Application filed August 1, 1906. Serial N 0. 328,723.

matic switch circuits, the trunks themselves being controlled by operators, who manipulate the automatic switches in order to effect connect-ion with the wanted lines as they are called for. In order to enable the operators to conveniently control the switches I provide each operator with a'plurality of push button keys somewhat similar to those used in computing machines, these keys serving to connect a power driven impulse trans- I cifically describe and claim, primary selector relays applied to trunks leading into auto-f mitter or transmitters to the respective trunks as they come into use and according to the numbers wanted.

This description is accompanied by figures, in Which Figure 1 shows substation telephone equipments; Figs. 2, 3 and 4 show relays involved in a system of automatic call distribution; Fig. 5 shows manual connectin units; Fig. 6 shows a selective impulse sen ing device; Fig. 7 shows an automatic switch or connector; Fig. 8 shows the scheme of the connecting relays of Figs. 2, 3 and ten and Figs. 9 and 10 show detail of a relay having a large number ofcontacts. Figs. 1

to 7 may be arranged to' form one large diagram of the system of my invention.

That portion of my system which is illus-.

trated' in Figs. 2, 3 and 4 constitutes what I' have termed the primary selector or answering portion of the system. I1 this, as already set forth, appear a nu. ber of ten point relays and a number of single point or ordinary relays. These latter may be of any suitable type. The only special feature required is that of double winding, which, as I shall point out hereinafter, can be dispensed with if some other means be provided for locking the relays when energized. The apparatus at the subscribers stations also forms no part in itself of my present invenlion, except as it co-acts with the apparatus. and circuits at the central office. I contemplate usiug an ordinary common battery telephone outfitthe same as those employed in standard manual switchboard systems.

Referring then to Figs. 9 and 10, I will briefly describe the ten p'oint relay, N. This comprises an iron back yoke, n, a pair of magnets, a, mounted thereon, an armature, n extending across the front end thereof, and a set of contact-springs, a n n n overlying the upper bell-crank extension of back yoke, n. Upon this return portion, a,

' ot the front yoke the upper bell-crank arm,

bcginning .with Fig. 1. showirtlnre subscribers stations, ilk,- ir. A

n, of the armature, "n. lies fiat under normal conditions. Cut from end to end of this upper bell-crank portion, n, are two grooves in which rest the insulating studs of the spring sets. The function of these slots with the studs resting in them is to retain the armature in place. At their front ends the springs are separated by shouldered studs, the lowermost stud of each pair resting upon the armature, carrying'the lower spring of its pair, 72., on its shoulder, and the upper spring, a, on its head, its stem passing through a. hole in the spring, it, while the mapermost stud of each pair rests upon the spring, 'n supports the spring, it, upon its shoulder, and carries the spring, at, on its head, its stem passing through a hole in the spring, at. The actuating studs a ll'ect only the springs, n, if of each set, those constituting the movable springs, while the others, n a are fixed. Each actuatingv stud carries the spring, n, on its shoulder, and the spring, at, on its head, ils stem passing through holes in the springs, a n. The entire relay is secured to an insulating hack block, 11. by means of the bolts, n,

constituting extensions ot the cores and threaded to receive look-nuts. The rear ends of the COIlttlClI-SIHITIQ'S extend out through openings made in this block, and an inclosing shell or casing, 02. is titted to the block. with which it forms'a tight joint all around the edge. This shell is secured in place by means of the stud, n, threaded to receive the nuts, 12.. As the armature. n is attracted, the springs. n", n, are lifted by the actuating stud, until their outer points make contact with the corresponding points of the springs, n, it, in each set. T a1 of these sets are line-contacts, and the eleventh is for locking purposes. as will sullicicntly appear 'trom the description of the circuits.

Following is a description of the circuits, Tl'icrciu I have V 7 each equipped with a telephone trai'ismittcr, a receiver. switch hook, a ringer, and con dcnscr. all of usual or suitable type for use with 'comnuin ha tcry circuits. ls hen the hook is up, that when it relicvcd of the weight oi. the receiver, the circuit through the transmitter and receiver; and when the hook is down, the line-carcuit is completed.

for alternating current only, through the ringer and condenser. Since the circuits are the same for all the lines, I will refer to the line from station A only. This consists of conductors 1 and 2, extending from the substation to the central oiiice. At the substation the talking circuit is completed through the wires 3-l when the hook is up, and the ringing circuit through the wires 5 (5 when the hook is down. These figures are useful for the purpose of tracing the circuits only. Turning now to Fig. 2, the line- wires 1 and 2 appear at the left hand side of the figure, terminating in contacts of the cutoff relays M, which are normally detinergized, so that in each case the line-wire 2 is grounded at 7 and the llllQ-WlIO 1 extended through lineil to the line-relay M, and so to main battery B and ground. The armature, m, of each line-relay M is grounded at 9, and when attracted is adapted to close upon terminal contacts of wires luiding to the tens and units relays of the primary selector sets. I preferably divide all the incoming lines in an exchange into groups of sayone hundred each, and to each group I apportion a fixed number of trunks leading to connective apparatus. In a small or comparatively inactive exchange the percentage of these trunks may be as low as five, and in busy exchanges it may be raised to ten or even fifteen. I assume, however, that ten. per cent. of connective apparatus will he sufiicient to care for the present system, hence I provide ten trunks for each one 100 hundred lines, and a complete set of tens and units relays in a primary selector group for each trunk. The circuits herein illusiratcd show six lines, which for convenience I will call No. 500, 50]. and 502 (Fig. 2) 1.05 and 510, 511 and 512 (Fig. 3). The subscribers circuits of Fig. 1 will fit any of these, and in order to fully comprehend the connections of these lines and the arrangement of the tens and units relays. it is necessary to consider Figs. 2, 3 and 44; together.

In 2 and 3 the subscribers extension lines are shown coming into their initial terminals on the tens relays. which are of the type shown in Figs. 9 and 10. Each of these relays carries the terminals of ten lines, and for each trunk there are ten of these relays, so that for 100 lines, provided with ten trunks. there will be 100 ton point relays, containing 1,000 linedcrmi'nals; from which it appears that each line can be multiplied ten. times, which it should be in order to obtain. access on (urcasion to every one of the ten trunks. The contacts on the ten point relays are arranged in duplicate pairs. That is, the incoming lines terminate each on one pair of springs, opposite which another pair of springs appears to which the line. is connected. when the relay is energized, and from which a local circuit passes tered. At the top of the figure I have shown to the front contact springs of a particular units relay or single point relay. For each group of ten tens relays there are ten units relays, or twenty relays in all for each trunk. .z-i group of this kind constituting one primary selector or dummy trunk terminal for thirty lines, is shown in Fig. 8, apart from the other figures, so as to free the lines from their multiple connections. In order to make clear the Connection of a line coming into the exchange, I will first refer to this figure and then trace the-circuits through the. others.

lin Fig. 8, N, N, N are three relays of the type shown in Figs. 9 and 1.0, having ten pairs of contacts each for the line circuits. These relays correspond to the relays shown in l i 2 and 3, correspondingly letthe terminal ends of lines 500 to 529,'inclusire, connected to a pair of contacts, n a, such as shown in the niechanicalfigures 9 and 10. For lines 500 to 509 these terminals are in the relay N. F or lines 510 to 519 they are in the relay N. For lines 520 to they are in the relay N Thus each relay contains line-terminals, a a, for ten lines. /Vhen any one of the lines appro priated to a particular relay is calling, the elcctromag'net, n, of that relay becomes energizaed. This will be explained in connection with the circuits of Figs. 1 and 2 farther on. For example, if any line from 500 to 509 originates'a call, the magnet, n, of the relay, N, will. become energized, and si-. niultaneously connect all of the lines from. 50 to 509 onto the extensions to 19, in elusive. If, however, thecalling line. is in the group from 510 to 519, the magnet, n, of; the relay, N, will become energized, connecting all that group onto the extensions 10 :"o la. inclusive. Similarlyflit the calling no he in the third group, from 520 to 529, the magnet, a, of the relay N will be ener gixed. coilnccting that entire group onto the extrusions 10 to 19, inclusive. Thus extensious 10 to 19- are seen to be common to all of the tens relays, and in fact each extension pair multiplied to corresponding contacts in al of the tens relays. No. 1.0 extension ;g'ocs the first pair of contacts, n, in each of the relays, l?l, N, N Exten l'fo. ll lllllllllplleflho the second pair r, contacts, a, a, in each of the relays, and so on with all the extensions up to No. 1%

at thr lower edge of Fig. 8, I have shown ten units re ays, marked P to P, inclusive. These are the same as the relays in Fig. 4, similarly marked. Each is a simple standard relay, of the type in common use, and preferably of the same general type as that shown in Figs. 9 and 10, hereof, viz., that type in which the elcctromagiiet is mounted horizmntally on a frame or rack, carrying the. contact'springsupon'it, and the whole l is inclosed Within a dust-proof shell. Each relay has an armature, 19, adapted to be actuated by an electromagnet,p,- to close together the contacts, 32 p and 79 p". In the present instance, that is in the trunk group of each primary selector, all of the contacts, 7 p of the entire set of relays, P to P are connected together, forming a set of double parallel branches marked to 29, inclusive, which are really so many open bridges across the trunk circuit, 3lv a The outfit shown in Fig. 8 is suilicient f0 30 lines and by its use any one of the lines, 500 to 529, may connect itself to the trunk 30-3l, by merely closing its line-circuit, and energizing the appropriate tens and units relays. The energizing circuits are not shown in Fig. 8, but will be described in connection with Figs. 2, 3 and l. They comprise pa allel branches closed by the line-relay of each line when calling, one

branch going to the z'q'ipropriate tens relay,

and the other ranch going to the appropriate units relay, which thus became energized simultaneously and act in conjunction to connect thatparticular line and no other to the trunk. For example, suppose line No. 512 is calling, the subscriber having taken down his receiver from the hook, so as to close his line-circuit similar to the ones shown in Fig. 1, and energized his line-relay, M shown in Fig. 3. This line-relay closes two branches, one leading to the tens relay, N,iu F 8, and the other leading to the units relay, P which is the third in the set of ten. The actuation of the tensrelay, NT, connects all of the lines 510 to'5l9 onto the extensions 10 to 19, inclusive; but it will. be observed that these extensions are open everywhere else, hence no effect is produced. by this action alone. The third units relay. I, however, connects the third extension 12 to the trunk 303l, through the branch 22, and by following the circuits in Fig. 8 it will be found that'this connects the line 512 onto the trunk direct, whereupon the trunk relays become energized, and further proceedings may be had. Only one line is thus connected to the trunk at a time, assuming of course that only one, tens relay and one unitsrelay of the same set be energized simultancously. It is true that the tens relay connects all of its lines onto the extensions; but all of these extensions are open except the particular one whit-his closed onto the trunk by the particular units relay energized. It is also true that the extension thus connected to the trunk is multipled to theeorresponding pair of contacts in everyone of the tens relays, but this produces no efifect, because all but one of the tens relays remain deenergized.

Before passingftfrom 8 it is necessary to call attention to the fact-that only three tens relays are there shown," accifinmodating necessary limitations of a Patent Office drawing, and it is to be understood that the same principles apply to any desired group up to or more. It is most convenient 111 a scheme like this to make use of the decimal system, using ten relays per trunk, ten lines per relay, and ten trunk multiples per line.

' For 100 lines there would be ten of the tens relays, N, N, N etc, .but still only ten of .the units relays, and each of the extensions 10'to 19, inclusive, instead of being multipled three tinies, would be 'multipled ten times, into all the tens relays.

Turning 'now to Figs, 2, 3 and 1 we have here the same relays described in connection with Fig. 8, but somewhat differently arranged. Only two tens relays and three units relays 01 each set or of each trunk are shown. I have assumed the numbers 51.0, 501, and 502 for the lines entering Fig. 2, and 510, 511 and 512 for the lines entering Fig. 3. The first three lines being within the same tens digits ofeachv other go onto the same tens relays in each set. For the sake of convenience I have given the designating numerals of the relays coeflicients, and have marked the three trunks in Figs. 4.-

I and 5 so as tobe readily followed. Thus in Fig. :4 all three of the lines come into the relay N, which is adapted to put them onto the extensions 10, 11, 12, etc, leadingto the units relays, P, P, P etc., in Fig. 41. (I should here remark that the tens relays in Figs. 2 and 3 are not shown with their full complements of springs, for tliesake of simplicity.) Each of- tlie lines 500, 501 and 502 not only terminates in contacts of the relay, N,-but is multipled to similar contacts in the relays 1N, 2N, etc. There would be one of these added for each trunk, that is appropriated to the group of lines. In the present case I only illustrate three trunks, so that each line need be multipled only three times.

In Fig. 3, the lines 510, 511 and 512 are connected to the tens relays, N, 1N- and 2N in the same manner as the lines in Fig 2,'each line being multipled three times so that each may have access to any one of the three trunks. It will be understood 01 course that the relays, N, N, of Figs. 2 and 3, and 'P, P, P, of Fig. 1, constitute one set, appropriated to the trunk 3031, and hate precisely the same relation among themselves and the same connections, as the set shown in Fig. 8. Similarly the relays 1N, 1N, 11, 1P, 1? all belong to one set, appropriated to the trunk-line 180131. Similarly again, the relays 2N, 2N, 2P, 2F and 21? belong to one set, appropriated to the trunk-line -230231. The extensions from the tens relays to the units are marked 10, 11,12 for the first set, 110, 111, 'and 112 and 53 iass along the bottom of Fi 's.

for the second set, and 210, 211 and 212 for the third set. As these of course bear a logical relation throughout, and follow the same arrangement as that in Fig. 8, it is thought no diiiiculty will be QXpOPlOIlCQd in comprehending the meaning of Figs. 2, 3 and I. If Fig. 8 is understood, the description of the other figures may be put into one sentence. They show several. groups like Fig. 8, with the line-wires multipled to each group instead of terminating as in Fig. 8 in single pairs of contacts.

The actual connection controlled by the relays N and P being thus understood, it is most important to explain the n'ieans by which I control these relays. Referring to Fig.2,the linewircs 1 and 2 terminate as I have stated, in the contacts of the cut-oil relay M through which they are normally connected-to the line-relay M and ground. lVhenthe subscriber at ration A takes the telephone from the book, he closes his linecircuit, .the linc-relay'M is energized, and the two branch circuits 50 and 51 are immediately closed. The branch 50 passes in. multiple to one winding of each of the three tens relays, 1*, 1K and 2N, these relays being double wound for the purpose of making them selt'locking when attracted. Any one of these relays mightthus be energized by any one of the three lines shown, but it is my purpose that only one of: them shall be so energized at once, and that no two lines shall be able to energize the same relay at the same time. Hence, on the other side of these'relays I take away the circuibwircs, which were designated generically by the numerals 5-1, 55 and 50, to three separate controlling means in the shape of specialrelays" associated with the switch trunks.

Each of the firstnamcd relays has its lock ing coil open on one side, but adapted to be grounded by the relayitscl'l in pulling up; and on the other side of this second or locking winding it is connected through one of the wires indicated by 57, 58, or 59, to controlling means similar to those I have just mentioned and which will also be specified later. The second branch from the line relay is marked 51 for line 502; 2 for line 501; and for line 500.- In other words, eat-h of these lines has its own units wire, as will be apparent at once if Fig. 8 has been understood. The three wires, 51, 52, 0

4-1 and 3 and into 1, where they terminate in the first or operating, windings of the three relays, F, I" midi, also by multiples in the corres nidiim windings of the relays, 1P, 1P. 1.. and 21, 2? and 21. The three relay long to the same set, have a common con; trol, their rcturn wires (of thesct 51) . n arked 51,51 and 54", passing to contacts I, 1 and. 1, since they be-.

in a twenty-pair relay D". This relay controls the return wires of both the tens an units relays of this set, twenty in all. I find it advisable to have a relay provided with separate terminal contacts for each of the wires 54., 5 B, etc., in each set 54, 55 or 56, because of certain complications which arise when battery is put on without any resist ance, the working then being on a margin which is too narrow to be called absolute. In other words, when the controlling relay for any set has cut off the return wires from the actuating windings of the tens and units relays, they are all separated from each other and as those of one trunk only are closed together at any one time, the separation of the relays associated with the other trunks prevents the formation of any parallel paths whena line calls.

Each of the units relays in Fig. 4 has a locking winding separated 'from the actuating winding and each locking winding terminates on one side in a contact normally open but adapted to be grounded when the relay is energized. All the locking wind ings of the first set or group have a common return, 61, passing onto the wire 57, which is the control wire of the locking windings on the tens relays,.N, N. This wire 57 passes into Fig. 5 and is there carried to a pair of the trunk relays by which it is controlled. The actuating windings of the units relays, 1P, IF, and 1P have return wires generically indicated by the numerals ($2, (and individually as 62, 62*, etc.), passing to the contacts of the relay 1D (of Fig. 5) associated with the trunk 130-131. The locking windingsofthese. relays have a common return 63, which goes to the wire 58, passing into Fig. 5 and there controlled by one of the trunk relays in the same manner as in the first set. Similarly, the actuating and locking windings respectively, of the units relays 2P, 2P and 2P have their return wires passing into Fig. 5 and there controlled by relays associated with the trunks It is thought the scheme will now be plain.

Suppose that one of the line-relays, as that of line No. 502, pulls up. It grounds the local circuits 50 and 51 and energizes which ever one of the ten relays, L 1N or 2N happens to be eligible, together with the appropriate units relay. This would be one of the three relays, P 11, or 2P in Fig. The tens relay and units relay thus selectel having pulled up, their locking windi gs are grounded, and hence they are maintained energized through the locking common re turn wire as long as a subscriber keeps-his receiver olf the hook, being finally deprived of current when the subscriber hangs up, so that'the relays are then restored. I have thus shown, first, a single trunk group of idle connector switch. wire 57 or 59 from the locking windings of primary selector relays, andsecond three such groups, or at least portions of three groups, belonging to three several trunks, and having the subscribers lines connected to them in multiple. I will now point out how a calling line is permitted to select an idle trunk only, by working idle relays only. For this purpose it is necessary that I should refer briefly to Fig. 5. This figure shows portions of a trunk circuit, each of which commences on the left of the figure, which is supposed to be the terminal point of attachment of the selective set shown in the preceding figures and in Fig. 8.

The three trunks are marked respectively 30'-31, 130-13l and 230-231. Each of them is divided by condensers C so that the portions to the right of the condensers in the figure can be used for sending direct current out through the switches without interfering with the incoming call end. I have designated the outgoing or switching end of the trunk as 30 ,31 etc. Across the incoming or answering end of each trunk is bridged a pair of relays D, D, 1D, 1D, or 2D, 2D, each with the main battery B between them. This battery is grounded as usual on its positive bus, and when the primary selector set first puts a call on one of the trinrks, as 30-31, its sleeve relay D will immediately pull up in series with the cutoil relay of the calling line. The incoming end of the trunk, therefore, corresponds to the answering cord circuit of an ordinary manual system, the primary selector set performing the same functions as the answering plug and jack; hence, the battery supply for talking as well as for signaling over the ca ling line is drawn through two relays l), D. 1) being the sleeve side relay, remains energized as long as the primary selector set is on. The relay, D, on the other hand responds to the subscribers acts, being energized by current coming over the subscribers line, and therefore controlled by his switeh-hook. It will be observed in the switching end of the three trunks shown in this Fig. 5, that in each instance there is a relay, E, but becomes energized when the calling plug is inserted in a trunk jack leading to an I run the common all the primary selector relays of each trunk toa back contact on the relay F1 this contact being normally closed upon main battery B, These relays are all energized when the switching is done, but they serve nor mally to keep current on the locking wires, so that when any set oi relays pulls up it will be enabled to lock instantly, even before the tip relay D of the trunk has pulled up. When this latter relay becomes energized, it takes control of the locking wire in every which is normally deenergized,

point out how the actuating windings of the different. selective relay sets are rendered active one at a time. This is by means of the relays D, D". In Fig. 5 it is assumed that the lowermost trunk is No. 1, the next above is No. 2 and the uppermost trunk,

3031 is No. 3, in the order of their becoming busy. The instant a call comes in and is put on the lower trunk, 230231, its sleeve relay 2D is pulled up and puts battery on the relay, 2D This latter relay is normally deenergized, and the actuating windings of the various tens and units relays belonging to its trunk are'therefore normally closed onto battery through the wires 56, 56, 56", 56, 56 etc.; there being twenty relays to the trunk and hence twenty wires for the actuating windings, l employ a ten-pair relay of the type shown in Figs. 9 and 10, at the point, 2D". Of course the sprin 's on this relay may be arranged to either open or close the respective circuits when the relay is energized, as the case may be. The relay 2D or the first trunk must open these circuits, Succeeding relays must leave them normally open and when energized must close them. In other words, as l have illustrated them in the drawings, the first relay 2D is normally closed when. deenergizcd, but all the rest of the relays in the series, as 1D are normally opened when det nergized, so-that the relay selector of the first or lower-most trunk is in condition to get current at once and hence will take the first call. As soon as this call is placed on the trunk, the relay 2D puts battery on the wire 14 leading to the armature of the relay 11) of the'next trunk, which normally completes the circuit of the relay lD The latter becoming energized immediately closes battery onto theactuating windings of the relay primary selector set of its trunk, which thereupon. become sensitive and in condition to take-the next call; and so on to succeeding; trunks. I have shown only five contacts on each of the controlling re lays, for the sake of simplicity in illustration, but it will be understood that there may be as many as are required. The relay D when energized closes the circuit of the signal lamp 0- through the normally closed contacts of the relay E The relay E is energized in series with the resistance coil 1 when the plug P is inserted in the jack J. The energizing of this relay opens the circuit of and extinguishes the lamp 7*. The relay E when energized connectspne terminal of the lamp '1 to ground and when the relay D falls back the other terminal oi. this lamp is connected to battery causing it to glow, notifying the operator that the calling party has hung up his receiver. The wires 15 and l6 connected to the tip and sleeve of the plug 1 lead to a set of buttons which control impulses from a sending machine.

In Fig. 6, Q", Q, Q, Q Q, Q, Q, etc, are a set of'wheels mounted. on and turning with a common shaft, which may be driven. in any suitable manner. The wheel Q), puts battery and ground alternately on the wire 20, which for purposes of illustration. represents the metallic shaft connection between the whecls. The wheel Q. is insulated from the shaft and is grounded and has an insulating spot in its periphery, andv controls by means of this spot the locking and. unlocking wires 30 and 31, in a manner which will appear from the statement; of operation. The wheels Q, Q Q, Q", Q, etc, are number wheels, the first one having one tooth, the second two teeth and so on up to ten teeth. (For simplicity of illustration only five wheels are shown). Around these wheels are three sets of pens, connected to the three sets of keys K, K K. As the wheels revolve from the position. in which they are shown in the figure, they first make connection with the upper pens q, then with the pens then with those of (7. The first set with their buttons or keys, K, transmit thetens'digit of any number, the next set transmit the units digit, and the third set transmit the ringing; number for party-lino work. All this will appear more clearly from the statement of operation.

' The keys, K, K K are of the sorallcd self-latching selective ringing type now in common use on manual switchboards, and employ the principleshown in the patent to Ham, No. 605,097 granted. June 7, M98. When any key is pressed down it pushes back the latch and releases the one that was previously down, then latching itself. Each set of keys has a'common wire, this lor the sets K, K, being marked 32, these two being joined together and carried to a bnch contact of the relay R, while that or the set K is marked. 33 and carried to another hack contact of the same relay, separately controlled. The numbers to be sent are set up by depressing the keys, and thr-u {he sin-1- nal is started at the beginning of a rolal ion of the shaft, when the first tooth ol each wheel is about to strike its pen 1 by the relay, R being dciinergizcd, while the relay R remains energized. The lriclc of this is in the arrangement of the spring pens q. 1,

on the wheel Q. This wheel is roiuledivith the others in. the direction of the arrow, and its insulating spot passes first under the (jfi spring pen 9, momentarily cutting ground oil of that and the wire 81, then under the pen 9, taking ground off of that.

It will be noted that the bank of keys is divided into three sets or rows, K, K and K respectively. The rows are each provided with the latching device of Ham, cited, the rows being independent of each other in this respect; thus one key and only one of each row will remain depressed, the previously depressed key of each row being released by the depression of anyother. In a bank or row of keys of this nature, a key is depressed through a travel carrying it beyond the locking point; upon release it returns a very short distance and remains locked there until released by the depression of the next key used. I take advantage of this detail in the row of keys K in the fol lowing manner: The pairs of springs as 70* are to remain locked when the key is pressed, as described later, but the triple springs in are springs requiring but a momentary contact to energize primarily the pair of lock ing relays R To secure the desired end, I so the relation of the springs is to the push button. of the key that they are closed by the button when at its point of farthest travel but are released by the slight return travel of the button before it is locked. The springs 7 2 however remain closed until the button is unlocked and fully released. V

In calling the number wanted which We will assume to be the operator plugs into the calling jack. then presses down but ton No. 3 of the set K; No. 2 of the set, K

and No. 3 of the set K The buttons of the sets K and K have their several individual wires connected to the pens on the several individual wheels Q, Q, etc, and the effect of pressing down the buttons as mentioned to connect the pen of the wheel Q through the springs 1 of the button l: to the Wire 32. wheel Q" connected throughthe springs M of: the button 71: to the wire33 and the spring 9" the wire The set of buttons K also have what i may call starting springs This set of buttons being: the last, or ringing set, the number is ready for transmission when any one of them depressed, hence any one of these buttons not only 'iinishes setting up the number, but by closing the springs 7. puts ground on the starting wires 3'7 and 3S. which pass to the two relays R, R res iievtively, and thence through the common return wire 89 to battery B and ground. Both the relays pull up, and both look, the locking circuit 01 the relay R being as follows: B, 35), R "1 30, 9 Q and ground. The locking (circuit of R is as At the same time the pen Q2 of the 7 p of the wheel Q." is connected through the springs For the button 70 to follows: E, 39, R, r'", 31, g, Q, and ground. Having'thus set up the signal and put it in condition to be started at the beginning of a revolution of the" main shaft, and having also plugged into the necessary hundreds group, the operators work is finished. She pays no further attention to the connection until the subscribers have completed their conversationand have hung up, whereupon the relay .Drcleases its armature, breaking the locking circuitoit' the relays of the pri- -mary selector; by the release of the primary selector relays, the connection between the relay D'and the cut-off relay of the calling line is interrupted, the relay D releases its armature, andthe lamp 7' lights to call for disconnection. The operator then pulls the plug P.

The signal having been set up as described, the apparatus of Fig. 6 then operates as follows: The wheel, (#2, in revolving will bring the insulating spot under the pen 9 at first, and might thereby cut oil the relay R prematurely, but this is provided for by making a branch locking circult 310 which is cont-rolled through a con tact of the armature 7" and a ground wire 36 of the starting relay it. Hence, as long as the relay R is energized, the relay It cannot be affected. Moreover, it will be observed that the wires 32 and remain disconnected from the wires 151(3 until. the relay RF energized, while therelay R is tle'energized. This condition is brought about wluen the insulating spot reaches the pen g. The relay R then lets go, and we have a continuous circuit from wire 32 as follows: 32, *1", 31', r, 16, (in Fig. 5), and to trunk wire ill. \Fe also have a circuit from wire 33' as follows: W 35, T 15, (Fig. and the other trunk wire 113. The insulating spot reaches the pen g just before the first tooth on each wheel reaches its pen 9'; hence soon as the above desired condition is attained, the set of impulses which has been determined by the key is of the set K comes from batter I over the wire to the wire 16 and so onto the wire 114: of thetrunk, through which it passes into Fig. 7 to the relay R which. will be presently described, and which I shall call for conveniene the vertical relay. At the end of this group of impulses, the teeth on the wheels will have gotten around to the pens and so the non. group of impulses determined by the key if will pass from ground onto the wire 33 and so to the wire 15 and the trunk Wire 113, through which they reach the relay ll in his. 7 which will also be presently described and which I shall for convenience call the rotary relay. The names of these two relays are quite accurate in this system, because the relay B does really produce a vertical motion of the switch the trunk wir, 11 1 and to the vertical relay R. After this, the insulating spot on the wheel Q reaches the spring 9' and momentarily cuts off the ground therefrom. Since the relay R is already deenergized, this breaks the locking circuit of the relay 1 and it lets go, disconnectingthe wires 15-1( -from the wires 31 and leaving the apparatus free for another operation.

Referring now to Fig. 7, I will briefly describe the switch operation. The switch spindle'controls a pair ofsprings s which it opens when it is down in its normal position of disuse, for restoring purposes, as

. will presently appear. 3 is the release magnet of the switch, which when energized removes the detent pawls "from the respective ratehets of the spindle, s, allowing the spindle to drop down and rotate back to zero, as fully described in the Patents 815,176 and 815,321, both oi lilarch 13, 1906, to Keith ct a l. This release magnet is under the control of the relay R which in turn is controlled by the relays R and R It is also under the control of the test relay R d3. is a ringing control relay,,E is a trunk cut-off relay and R is a ringing relay controlled by the commutator X which conimen to the entire exchange. it is a slow acting relay, prei' n'ahly a solenoid, which connects the test relay R, at the moment 01 eil ecting connection, as controlled by the first ringing impulse, and at the same time opens the generator circi'iit 14-O1 t1, while the proper current is being selected. 11 to R, inclusive, are selective relay." for enabling one or the other of the ringing generators, (i, G", G and G, to be connected onto the ringing contacts oi the ringing, relay, it, the particular generative being ditermined by the number of impulses received through the relay it which operates the relays it, it, etc, in succession, ca :h of them locking as it operates.

The o icration of this trunk scheme is as l follows: in selecting the number we have assumed 32* (the trunk itself corrcspomls to the hundreds number, if such there be) we have first three impulses from battery over the wire 11% to the relay it, then two impulses from ground over the wire 11?) to the relay PM, and then three impulses from battery over the WllOlll to thi rclay R. The first three impulses coming over the wire 11-icauses the relay ll to pull up three times, each time closing the 'lollowing circuit; 13, 142, 143, 1 1-1, .9, 1&3, 1-16, 1 17, and ground to battery. The vertical magnet 8 steps the spindle s of the switch 11 3 three steps, so that the wipers s stand opposite the third row of contacts. 'llwo-impulses then come over wire 1.13 ailecting the relay R which pulls up twice, the first time closing the following circuit: B, 1 1-2, hf, 1 1-9, armature of R ,-a1-1natiire of R 151, to ground and to battery. The relay R instantly pulls up, cutting oil the vertical magnet, 8 and locking itseli by the following path: B, 1-1-2, it, 1*, 152, 151 and ground back to battery. The vertical magnet s is therefore cut oil for the rest of the transmission. The rotary magnet 3, however, gets current each. time the relay R is energized, over the following path: B, 1&2, 14-3, 114-, a", armature of relay R 15%, 155 and ground back to battery. The rotary n'iaguet '3' turns the spindle 8 two steps, so that the wipers s rest on the second pair of contacts in the third row, or No. 32. Three impulses now come over the wire 11%, causing the relay R again. to pull up three times. Each time it closes the following local circuit: I), 1 12, R, 157, 1 1-6, 141-7, and grmmd hack to battery. As a branch of this same circuit, the wire 1438 comes in from battery wire 112, through the solenoid ll and goes to 157, 11H), 1-1-7 and ground. At this point in the dcveloynncut of the connection immediately Following the closure or the contacts-of relay l? at the beginning oi the first gcnci'ator-selectiou impulse, two things occur simultancmlsly:

(1) The solenoid R attracts its core, opening the wires 110 141 and closing the switch 16?] whereby a test circuit is formed through elements ll, 1-1-2, 1(32, 1, 16?. to upper s, which at this moment is resting 'in contact with the line selected through the" agency of vertical and rotary magnets a 8"," it the line be busy because it is calling, then a circuit will exist from upper wiper 3 through the line multiples to the tip side of the other trunk used in answering, and, thrcugh the relay 1) of that trunk to ground; while if the line is busy because it has previously been called then the test circuit will continue through the line multiples to the wiper s of the other switch used, in calling the line, thence through the other trunking equipment following a path corresponding to contact of ll, contact oi It, conductor 11 and winding of lit to ground; in either case the test relay R will be energized and in turn will energize the release magnet s. it, however, the selected line with which the test wiper rests in contact is not busy, no circuit will exist from lhat lest wiper to ground and the test relay it will not be energized;-

' a branch path for the conductor H33 exists through the talking conductor of the lruult to lhc left hand contact of relay it and thence to an armature contact of relay R where it terminates open, but subsequent to the cnergization of relay It as about to be describedfthis branch path passes to the inner contact of the left hand armature of that relay and thence over the conductor 141 to the right hand switch of the solenoid .R which during the test period is open, and thus test relay It has its circuit open at all points and the design of. the device as a Whole is that no OHGI'g'lZZttlUIl of that relay may result when the line selected is in a condition of disuse and subject to use in the connection now being established.

(2) The relay It is energized over the path B, 142, R 157, 14:6, 147 and ground. By the closure of the left hand armature of relay t circuit is formed through elements B, 1.42, 156, armature of R, 160, winding of R 161, switch 8 and ground, energizing relay E which leeks itself energized over the circuit B, 142, 1-1-3, armature and inner contact of relay it", winding of relay it, 161, s 'and ground. This energization of trunkconnecting relay It connects the conductors 1li-113 ot' the trunh through to theoutta' contacts oit't-he ringing relay R and through to the wipers 5". This furnishes a path through test relay It as follows: B, 142, 162, R 163, talking conductor to left hand armature of R back contact and talking conductor to armature of energized relay lt", conductor 114, winding of relay It and ground; how= ever, this circuit is adapted to be opened by the attraction oijithe arm: tures of relay it and it is the function of the connector switch that the o )enin of this circuit at It shall succeed its closing at 1t b a time limit so small that restoration of the connector switch is not pern'iitted. it will he noted in the study of this time element that the test relay lt must attain the degree of mag netization. rri uired to attract iis arn'iutnre, must swing its armature through its full travel. to close its contact, "and that subsequently to the closure of the contact ol' R the release magnet a" must reach its required degree of magnetization and must overcome the inertia oi its armature and more it through some definite arc hetero release of the switch will be ellected; this series ol' neev Marily consecut ve operations limits the duration of the iuomenta l'alse test here considered. The commutator X is carried. upon the shaft which =arrics the number wheels and commutator devices: Q, Q, Q.

(a etc, and the commutator X is adjusted angularly with respect to those wheels so tlr" the conducting portion of X. isin clertriral warm-mien with its brush at the time that thrern ririzaation oi relay lt' occurs. it is seen the: to

contacts oi" relay it. by which current flow thrinre'h test relay it was permitted, rur

rent flow also was sinuutruieousiy provided for thron h the )Hlll 13. H2 H, \UWUHT of o l a a cs y It, contact and armature of r, 168, r, 101

and ground. Thus current begins to flow through the winding of relay R at the same instantthat current begins to How through the Windingof relay R and, assuming equal speed in the operation of armatures, relay It will have moved its armature and will have broken its back contact, thereby cutting off current from relay B in ample time to prevent the restoration of the switch by operation of release magnet s, the break at the armature of R probably occurring in time to prevent anycontact what ever at the armature of relay R Thus a test condition is maintained with the test wiper a. isolated from the winding of relay H. by the break at the armature of relay 1t, and the design andadjustment of the commutator X shall be such that the relay it is held energized through the maximum period occupied by generator-selection impulses and until the opening of the circuit of the test relay 1% by the opening of the switch 162 upon release of the armature of the solenoid R". The armature of the solenoid R issluggish and does not open the switch 162 between the generatorselection impulses, so that the test circuit here described is maintained contimiously during the period of generator-selection.

Leaving the various parts of apparatus in the condition now considered, we will follow the action of the apparatus in response to the genorator-selection impulses. In the instance assumed, ice station No. 3 is to be called three battery impulses will be received over the wire llatoperating the armature of the relay it successively three times, which in turn acts over the path 14:7, lit 157 it, etc, to operate the armatures of relay it in SIICCUSSlOI]. three times; the armature r through its front and back contacts eti'ects the selection. of the desired ringing generator as follows: Upon attraction of r the first generatouselection inipulse, it makes electrical connection with its inner contact, but inasmuch as the Wire 16d is open at the armature of relay R no complete circuit is closed. Upon the release of the armature r at cessation of the first gen erator-selection 'impuise, circuit is closed through elements I), 1 4-2, 113, contact of R 5, H30. 1-, 16?, contact of 1:1 winding of R and ground. energizing relay R which locks over the circuits B, 1.42, 1-1-3, contact of 11", nee. 1 W. armature and contact ol it, windingoi R and grrnind. ll but one gelierator-selhctiiin impulse were received, the gg enerator (i would remain in .ronuection nith conductor 14o ready for re that by the closing of the 1 connection through conductor Il-ll to the ringing relay 11". At the l'ieginnlng oi the second generator-seleetion impulse, relay l? is chore" .ed and armature r is altrartwl,

(losing r nit through elements B, 14.2, 1'10, contact of R 160. r", 164, closed contact .contact of R 160, 169, armature contact and winding of R Upon the cessation of the second generator-selection impulse, the armature 1' is released, closing circuit over B, 142, 1&3, contact of l 160, T, 165,

closed contact. of lower armature of energized relay R back contact of lower armature of unenergized relay R", winding of relay R and ground, energizing relay R which then locks itself through its own contact by current received over conductor 169 toground as in the case of relays R and R. If no more generator-sclection impulses were received, the eil'ect of the two impulses thus far followed would be to leave generator Gr connected to cmuluctor 140 through contact of energized relay R, that being the proper generator for ringing the secondstation on a party line. At the beginning of the third and last generator-selection impulse, the armature r is again attracted, closing circuit over elements B, 14-2, 143, contact of R 160, 1- 164-, closed contact of energized relay R closed inner contact of energized relay R closed outer contact of unenergized relay R winding of relay It and ground, energizing relay R, which then locks itself by current through'its own contact. and winding over conductor 169 to ground. Upon the cessation of the third and last generator-selection impulse, the armature r is released, closing circuit through elements B, 142, 14-3, con

tact of R 160, W 165, closed inner contacts of energized relays R and R closed outer contact of uncnergized relay R Winding of relayR and ground, energizing relay R which then locks itself by current through its own armature contact and winding from conductor 169 to ground. This leaves relays R and 1t" energized and leaves relays R unenergized, thus effecting the connection of generator G to the conductor 140, and as the generator-selection impulses now cease, solenoid R releases its armature, opening the circuit of the test relay R and closing the circuit between conductors 140-141, thus connecting the lected generator Gr over conductor 1-11 to the inner contact of the left hand armature of ringing relay l1 and thus through the upper wiper s and to the line conductor of the selected line to ring the third station upon the party line selected. The ringing will continue until the insulated portion oi the commutator X passes under the brush of that commutator when the circuit of the Winding of relay R will be interrupted and by release of that relays armature the circuit from the wipers s will be removed from the generator and carried to relays R and the relay R.

It respectively. The line selected will be subjected alternately to periods of ringing when the relay tis energized and to periods of non-ringing when the relay R is deenergized. Upon the answering of the called sub-station, or of any sub-station upon that party line, during a period of non-ringing, current immediately will ilow through elements B, 142, winding of R 113, lower a, line conductor, substation bridge, return line conductor, upper s, 114-, winding of R and'earth, energizing R and attracting its armatures.

By the operation of the left hand armature of R, circuit is closed through elements B. 142, left hand armature and inner contact of R, winding of R 15 1;, contact and left hand armature oi R 155 and ground, energizing lt which then locks over the circuit 13, 1 12, right hand armature and contact oi? R to winding of R 1534-. contact and armature oi R 155 and ground. By cncrgization of relay R ground is taken oil oi? wire 152 so that ringing relay R may not again be energized. Also by the energization and locking of R the relay R is rel :ased and remains released throughout the remainder of the connection. This is the condition of conversation and continues until the hanging up of the telephone and the breaking oi the substation bridge upon the rallcd line. Upon the hanging up of the telephone and the breaking of the substation. bridge upon the called line, disconucctimi of the switch is eifccted as follows: Circuit is interrupted over the return wire oi the line and through relay R to ground, releasing the armatures ofrelay R, but current continues through elements 1%, 142, winding oi R 113, lower wiper s, and the sleeve side of the connected line and the winding o'ii its eut-oii' relay M to ground, maintaining the energization of This will be apparent from an cxan'iination of Fig. 7 in connection with the line circuits in Fig. 2. The circuit from R to lit" is closed through the line sleeve multiple and the wiper s. liy the release of the lcit hand armature oi relay ll a. release relay circuit is established through elements B, 142, left hand armature and outer Contact of dei'nlergized relay .li, winding of release relay it, inner contact and armature r of relay R 151. and ground, energizing release relay l t" which, by closing its contact, energizes release magnet s. which ,ci- 129 feels immediate restoration oi all parts of the switch to the normal position of disuse.

A consideration of test conditions during the process oi the connection is desirable. When the test wiper or upper wiper 3 connects with the test conductor of the line, no

action is taken either to test for busy or to place a busy test upon the line until the wheels Q, Q Q3, etc., have in due course tor-sclection impulses the test relay is taken off and the ringing generator is substituted. From this time a'busy test guard condition is placed-upon the test conductor of the selected line, being alternately the potential of the selected ringing generator when the relay It is energized, which is sutlicient to energize any relay R which may test the line during the interval of ringing, and between the intervals of ringing the busy test consists of the ground circuit throng 1 the relay R tested for busy by some other connector attempting a connection with it and during the interval of decnergization of ringing relay l a current will flow from the c0nnec tor thentesting tothe test conductor of the line, thence through the test wiper of the connector at l 3 l'iolding the line, and through back contact of relay it, front contact of R 114, and winding of R to ground. This current will be of suliicient strength to energize the test relay 1 11 of the distantconnector attempting to take the line being held, and this will eli'ect disconnection of that connector but it will not be of suilicient strength to energize the relay It ii'iasniuchas by the encrgization and subsequent deih'icrg ration of that relay, the said testing current would also restore the holding connector of l ig. 3 to its normal condition of idleness. The relay l) in Fig. 5 falls back when the calling party hangs up his receiver thus opening the lo( hi1u wire 5T allowing the primary selector outlit to become di connected. The relay l) falling back closes the circuit of the lamp 1' notifying the operator that the parties are through talking and she thereupon witlulraws the plug from the trunk jack.

I have thus described my invention 'in one specifi form for the purpose oi rendering it clearly com n'eliensible, but it is to be under stood that l do not limit myscll to the spewith form or arrangement deseribeiil. 1 may vary the methods and n'iattcrs described in many ways without; departing from the spirit of the invention. 1 wish particularly to call attention to the fact that there are certain features of the invention which should not be limited to use merely in combination with others. ll'hus, those portions oi? the invention shown in l igs. l to inclusive.

arc coi'nplctc, and the connecting jacks .l in r .r ig. 5 may well be the multiple jacks oil: linc :ircuits, omitting the autcmratic switches enti In such case the apparatus in l ig. 6 "could be superfluous, and the cord circuit would contain the ordinary o 'icrator s listen- If the line thus connected with the 'ing and ringing key. The same may be said as to completeness of that part of the invention embraced in Figs. 5 to 7 inclusive, the incoming trunk ends being then taken as lines merely. All minor changes and adaptations; as Well as sub-combinations, I Wish to include in the scope of my claims.

In the claims hereinafter I shall refer to y B switches to indicate switching mechanism which is definitely directed or driven to select a particular line. The letter B is used as a convenient designation for this type of switch because it is one of the algebraic symbols for known quantities.

Having thus described my invention what I claim and desire to secure by Letters Patcut is:

1. In a telephone exchange system, a plurality of line circuits to be interconnected, a plurality of terminal plugs less in number than the number of lines, and groups of relays associated with the respective plugs, each group common to a plurality of lines and containing terminal contacts thereof-for connecting any line when calling to an idle terminal plug, together with automatic switching apyiiaratus containing multiple terminals of the lines, and jacks forming terminals forthe switch circuits, adapted to rece ve the plugs, whereby calls made over the lines will automatically distribute themselves upon the plugs, and the plug circuits may be trunked to automatic switches for the purpose of completing the connections desired.

lira telephone exchange system, a plurality of line circuits, a'plurality of terminal plugs, groups of relays common. to said lines, one group associated with each plug, for a utoinatically connecting a calling line to an idle plug, a signal associated with each plug and becoming active when a calling line is connected thereto, and automatic switches cooperating with said plugs to complete the connections desired.

3. In a. telephone exchange system, a plurality of lines to be interconnected, and connective apparatus therefor comprising the tollowii-ig lllfniji'llllltilll'illlillQS; terminal plugs, primary selector switching relays in decimally arranged groups containing line ter minals, one group associated with. each plug, for connceti the calling lines with idle plugs :uitoinatic switches and jack terminals tlmrcior, together with manually operated controlling apparatus for the switches.

4-. ln. av telephone exchange system, a. plurality ol. lines to be intel-connected, and conncrtirc apparatus therefor comprising the following instrmnentalities; terminal plugs, primary selector switching relays in decimally arranged groups containing line teriniuals, one group associated with each plug, for connecting the calling lines with idle pl ngs, automatic switches and jack terminals

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