US1470664A - mcberty - Google Patents

Description

ca. 16, 1923. E 1,470,664

F. R. M BERTY AUTOMATIC TELEPHONE EXCHANGE-SYSTEM Filed Nov. 12, 1995 6 Sheets-Sheet 1 W E E E lllllnu-.......--uu| Z052 M? W j j 5 fizanfzf 26kg Oct-16,1923. 1,470,664

F. R. MCBERTY AUTOMATIC TELEPHONE EXCHANGE SYSTEM Filed Nov. 12 ,1905

e Sheets-Sheet 2 6 Sheets-Sheet 5 F R M BERTY AUTOMATI C TELEPHONE EXCHANGE SYSTEM Filed Nov. 12, 1905 Oct. 16, 1923.

Oct. 16, 1923..

- 1,470,664 F. R. MCBERTY AUTOMATIC TELEPHONE EXCHANGE SYSTEM Filed Nov. 12, 1905 6 Sheets-Sheet 4 Oct. 16 1923.

F; R. McBERTY AUTOMATIC TELEPHONE EXCHANGE SYSTEM Filed Nov. 12, 1905 6 Sheets-Sheet 5 Cd. 16, 1923. v

F. R. M'CBERTY AUTOMATIC TELEPHONE EXCHANGE SYSTEM Filed Now. 12 0 6 Sheets-Sheet 6 Patented Oct. 16, 1923.

FRANK MoBERTY, EVANSTON, ILLINGES, .QSSIGNOR, BY MESNE ASSIGNMENTS, TO

ELECTRIC COE'HANY, INCGIZEGBATEL, A CORPORATION OF NEW' YORK.

" Application'filed November 1 rowing 1 scription'.

switch 7.

7 0 Be it lnown that I, FRANK Rt, MoBEni Y,

citizen of the United States, residing at lflvanston', in the county of Cook and tate 01 Illinois. have invented a certain newand useful I" provenieut in Automatic Tele phone- 3x0 range systems oi which the foliull, clear, concise, and; exact delily inv ation relates to switching apparel ins and cuits' use more particularly in telephone exchange systems and its object is in general to provide improved means for lines for the purpose of comn1uni--' cation, and for performing various selecting, I

signaling and other. operations incident thereto. By employing the full equipment.

herein described it is possible to dispense with the services of a central oliice operator and provide for complete control of the au toniiatic switching apparatus by the subscrih ers but'the invention is not limited in its application to a full automatic system; as

ma: y of the features described may advantageously be adapted independently or the oth s. indifi'erent types of systems.

Another object of my invention is to provide improved and novel .means, whereby a calling; l ne may be servedby' any one of a pluraiity ofconnecting circuits, eacl dapted to inter line called the selection of such connecti circuit by the calling line being accomplished hy apparatus operating automatically and initially controlled the calling line.

'Another object or"- my invention is to pro vide new and improved nieans,'\ vhereby a plurality of lines terminating in the e);- cha'nge may be normally a sociated for call-- ing with an idle oneoi't' a plurality oitcounecting' circu ts, each adapted'to connect line to a called line and apparatus operate il ipon the taking for use by one of such lines of the connecting circuit with wliichthe pluralityot' lines is normally associated. for transferring the remainder of such lines intooperative relation witli' an-' other idle connecting circuit Another ohqect o'i" my invent on s to provide n w and improved circuits and electro- 7 magnetic controlling apparatus, whereby the operation of the selector through which a :onnect such line with a AUTOMATIC TELEPHQNE-EXCHANGE SYSTEEI.

2, nice. Serial no. 1802.358.

connecting circuit is connected to a called line may be accurately controlled and the operation of such selector accomplished in a. v v speedy and eflicient manner.

Anotherobject of my invention is to vide novel and e'iiicient means, whereby a test may bGHlflClQOf a called line, and it upon such test the line should be found busy. a busy signal will be thereupon automatically transmitted to the calling party.

A further object of my invention is to provide new and improved means whereby upon the testing of the desired line, it such line is found to'be .in'idle condition, a source of ringing current will be automatically applied to'the terminal of such line for ringing the calledparty; and my invention further provides that thereapplication of such ringing c'urrent may be under the control of the calling subscriber.

lv [ore particularly, my invention relates to a switching system involving improved organizations and arrangements of circuits and apparatus for facilitating the interconnection of telephone lines and the various features of my invention are shown more particularly in thisapplication with reference to a full automatic telephone exchange system, in which the entire operation of the system for the interconnection of subscribers lines is'under the control of the callirg subscriber. It must not be understood, however, that my invention nor-any of the several features thereof. are confined or restricted to the particular formshown herein, nor to the particular characteroif system indicated by the form shown herein, but may be used whereverapplicable or of advantage.

In accordancewith. one feature of my in ventionl provide an-excl'iange system a, plurality otconnectingv circuits for the lines together with automatic transfer mechanism whereby an idle one of said connecting circuits is maintainerl' in operative relation to the lines and automatic Y switches or line finders, preferahly one for each connecting circuit, adapted when suitable controilinging circuits and therefore the line finders may be less in number than the lines which pro- ' tothe terminals of the associated with a given they serve. The controlling apparatus for the lines may be located at the substation and may comprise switches or keys actuated when a subscriber initiates a call. The trans fer mechanism preferably comprises relays, one "for each line finder, said relavs being arranged. so that when any line finder sei' a line calling, a relay is energized to shift the controlling circuit from the motor ineehanisni of that line finder tothe motor mechanism of another idle finder in the series. The line finders themselves may be rotary switches having points of contact or tionary terminals for the lines and travelrug brushes or contact members tor-mingl- -movablc terminals oi the connecting cir-' cuits. The lines are connected in multiple several line finders in multiple also to the terminals oi selectors for making connection with the wanted lines. In actuatingthe controlling apparatus when calling, the subscriber causes the electrical condition of his line at the terminals or stopping points of a roup of tinder-s to bechanged and at the same time causes the motor mechanism ofthe particular idle line then in association with the group to drive its brush over the terminals oi the lines in succession. l Vhen the brush reaches a circuit is mechanism the terminal of the'lin'e calling, closed for a stop magnet or othel so that the brushes remain at that point in .rnakin'g connection with the wanted line has tcstin; means placed in operativecondition when the switch has advanced to the terminals of such line and then actuated if the line is idle to energize a circuit including an electromagnetic device which in turn connects the ringing}; generator in circuit with hthe wanted line.

In accordance with another feature of my invention I provide in association with each selector switch a pair of devices which cooperate with the'controlling apparatus to govern a double movement of the selector, preferably in long and short steps, together :with transfer mechanism for shifting the operative relation of the calling i'i'iechanisn'i from one of said devices to the other. These devices are preferably interrupters inter-- mittently operated in the movement of the selector. As shown they are toothed or notched wheels, the distance between the group of lines and 'sociated tl'ierewith.

the automatic finder apparatus associated with said connecting circuits by which a calling line is united witha connecting circuit and as outgoing terminals? where they appear in the automatic selector switches associated with said connecting circuits, by which said connecting circuits are adapted to be connected to a called line. apparatus referred to involves structurally a contact arm carrying a plurality of con' tacts'adaptcd tornove such contacts over such incoming terminals, and to cause them to make contact therewith; Sii'nilarlyithe' selector switches each comprise a contact a an adapted to sweep over such outgoing terminals andupon the selection of the de sired line to cause such contact devices to make contact with the outgoing terminals ofsuch line. '9 I The preferred form of my invention, therefore, involves, briefly, telephone lines and a plurality of connecting circuitslex; tending between finder devices and selector switches, each such connectmg circuit ha ing individual thereto and associated-therewith one of such finder devices and selector switches and being connected to contact de vices upon their respective contact arms. The substation comprising a part of each telephone line may beand. is preferably pro vided with the ordinary and usual. suhsta tion equipment and is further provided with.

The finder l r switching or sender apparatus adapted when one of said connecting circuits and the finder apparatus and automatic selector switchas' My invention is illustrated with particu- V lar reference to theaccompanymg drawings which illustrate an embodiment thereof, in

which c Fig 1, is a front elevation of the terminal support and movable contact arm found in either the finder or the select-or described herein;

Fig; 2 is a sectional view on line 2-2 of:

ling-1,

F ig. 3 is a plan view of my improved automatic selector switch, together with the mechanism associated therewith;'

' Fig.4 is a vertical sectional view on line erred i ii Fig. is a rear showninFig. 3; 7

Figs. 6' and 7' constitute, when taken to-' gether; a complete diagrammatic showing of elevation of the apparatus 7 one form of my invention and illustrate two telephone lIHGS GXtGDChDg from substations to an exchange; a connecting circuit for uniting such. lines and efinder and selector associated with such connecting circuit adapted to unite with snchxtele fl one lines. re'spcctirely ns such] lines may be calling or called lines, the system as shown involving the circuits organizations of the pre- The) I s of reference designate the suit cl; of the figures oi the drawings. i V

I Referring first to tl'ie'struct-nre of he find: erdevic'e' and the'eutomatic selector switch, Figs. 1 to 5, inclusivegshow theipret'erred form o the automatic selector switch used inconne-ction "itli'iny inventiongthe findr device heinpyof similar construction as re nerds the ternii'nil mounting and the nert ble contact arm',-.en'd difiersfhut little'e'iccept in the 'zzrrang'ement ot circuits and electro magnetic operating mechanism fr 212 the s let-tor switch. p 7

The terminal inoiintin'gC of the finder or selectot is mounted upon a suitable support C end-hesmonnted thereon e'plnrelity of set oticonnection terminals, one set of te' 1 o each line entering the exchange, terminals m each comprise iinsls' two of which servees the s of the telephone lines with which zissociz ed; while the other two ters tor-in" ports of local circi "ts associwith such ine in the exchange.

centrzill ot the terminal support i I Misses longitudinally a she mounted to rotate on suitnhle herirings. and hering'the err-.1 Drin'idly secured thereto upon the same side otthe terminn support C that the tcrininnls appear. 'This arm D is provided with inwardly pro'iectingz portion D to which is pivotede contact carrying: arm F,

i in metliotely ailscent the electronmgnet and is adopted ""orin'the armature ofsnch magnet Upon which encircles the she.

ie pivot thereofare mounted four coll-e wnizn are slid devices or nween t' V of the ces-snd the (,Olllil'S 'o't isuleting' nietci ml in such s-ninnner t1 they tend to force the needsot'tlie contnct devices sway front the insulating collars end in the direction-oi the connection terminals and the ter nalfsu p'port C. One or'nioro or" said springs aiichits associated" cont-act; device;

an electroinngnet G through which contact arm at the end remote from which is arranged to be maintained in con- "r i V et G isenergized in any position he contact arm F the arm will be drawn up close against the electromagnet and all.

tour of the contact devices I, I, I Ffwili' be forced into engagement with the c0-opersting connection terminals to which they area: that tinie edit-cent; the magnet G It the-51111116111116lockin the contact arm 1* in the-position which it then occupies.

Eigidly fixed to the shaft E is a gearwheel- K, whichgeerwheel meshes with a train of" power driven gears forming a part 'to drive the gearwheel K and throu h it the contact arm F. The opera tion' of the clockwork mechanism, however,

is normally prevented by a stop arm or clnich L controlled by'the electromegnet M. This stop arm L engages the clockwork mechanism while the electro'magnet M is in its 11 znel and'd'eenergized' condition, and it I therefore heseen that when the magnct is energ zed thefclockwork mechenisin will drive the shaft E and move the contact arm r until SHCh'tHIIB as the electrois e' ein deener ized. This ar- :1 23 L ticiileri orm "ot motor mechanismgwhile it, iswellfadept'ed to the purpose in hand, it must l'lGUiKiQI'StOOCl, is" only typical and my ni'enti'onis not restricted to this particular rn'i Ftmn'y involve. in'suhstitution therefor: any other i'orin or", motor mechanism adapted to-pertorm the same tiinction.

Upon the end of the shaft E adjacent to the contract arm F are mounted "four insulojtedmetallic rings Ni Nhhl N which are electri'cnll connected with the contact dean es i; .l. 1-. it. cerr hythe xii-2n i Con-- I a t. 1 r 2 s trici hplli fi 0. (l Q Q are mounte lnpon an in'snhitine block P suitably secured to the em ort (l and ere a'rrzinged to bear upon the said rings, these springs serving es teri niinsls tor the connecting circuit and local circuits will he hereinafter described.

'3 he apparatus thus "far described is commen to both the finder device and the auto matic selector twitch in the form of my in- YGDl'lOH shown herein. This apparatus. however when used as a selector switch has in addit on associated therewith three contlClFITllli-EDQ wheels R, T and S rigidly secured to the shaft E et the rear of the epnst which con zict nie'kine wheels are severallyziclnptetlvto control the circuit of the release-magnet M. The "contact-making clockwork escnpement mechanism mwheel which servesas an oil-normal 'one cooperative relation with the next set of switch, is provided with but a single depression in its periphery in which, in the nor mal. position of the selector switch, the contact spring R rests.- When, however, the selector switch moves from its normal position the contact spring R rides upon the periphery of the wheel R and comes in contact with the contact R These contacts R and R will then be held closed until such time as the selector switch is again in its normal position, when the contact spring R will again enter the depression and circuit will be broken between such contact spring and contact R The contact-making wheel S operates similarly to close a circuit at the contact spring S and the contact S but the depressions in the periphery of the wheel S are of such extent and are so spaced that the contact springS will only be in contact with the contact S while the selector contact arm is moving-from.co-operative relation with i set of connection terminals into terminals. The contaet-malring wheel T also operates similarly to cause the contact spring Thto make contact with the contact T but the depressions in the wheel T are i of suchextent in this case and are so located that while the contact wheel T is passing from one depression to the next, the selector contact arm will be moving over ten sets of connection terminals. It will-be obvious of course, that in a selector 1n wlnchthe sets of connection termmals are arranged according to some other system than the decimal system otnotation. that the relation of the distance moved by the selector "while the contactsS and T are movedflfrom one'de pression to the next upon their respective contact making wheels may be changed as i may be required.

lar connect ions'and disposition of apparatus. in this system. shown inclu d '2 Two telephone lines are the usual substation apparatus and are generally indicated as A and B r tiyely. The line A. for purposes of illrst liner and it is assumed that connection is desired by the subscriber A. with the line At each substationin addition to the or-' dinary telephonic apparatus there is located additional switching or sender apparatus comprising the switches 7) and If. the switch 7) being adapted upon its depression to connect t-he limb ot the telephone line to ground, and the switch I) being adapted ation will be considered as the calling upon its depression to connect the limb 2 of the line to ground. These switches b and 6 may be of any desired character, but. are adapted to be independently or simultaneously closed and opened'as maybe found DECGSSRIY.

The first act of the subscriber A to bring about the .establishment of the connection desired is to depress and thereby close both of the switches 12 and 6 thereby grounding both limbs of the telephone line. The

c osure oi? the switch 5 establishes a circuit from the battery 6, magnet M, conductor 3,

back contact and armature of. the relay 1), back contact 03 and armature d of the relay (Z, limb 1 of the telephone line and switch 5 to ground andvback to battery.

The closure of this circuit serves tov oper- 1 1 and 2 respectively. The terminal a is connected by the conductor .4 and the back phone line, being connected to the limbs contact (I and the armature. d of the relay 7 cl to limb 2 of the telephone line. The connection terminal a is connected by the conductor to the relay (Z and thenceto ground.

These connections a20 a", a may be multipled as may be desired and do, in fact appear in each of the finder devices, one of WhlCh finder devices is associated with each of the connecting circuits of the ex change, there being as many connecting circuits as may be necessary to properly'carry the traliic of the exchange. As is indicated at the top of Fig. 6 thelimbs 1 and 2 of gory the telephone line may be also multipled to outgoing connection terminals appearing in each of the selector switches, whereby the telephone line A. may bereache l by some other line when such other line is calling, the lowermost terminal of the line finder F being connected to the lowermost ter-. mmal of the line connector indicated above ing circuits is shown in full; sufficient of the associated circuits vand apparatus of a second connecting circuit being shown, however, to make clear the manner in which 1 connection will be made with a second'connection circuit in case the first connecting circuit is use as will be hereinafter set forth.

The contact arm F in its movement causes the contact device I which is the contact- 7 device adapted to normally make contact with its cooperating connection terminal, to trail over andmake contact successively 7 with the connection terminals a or" there spective lines. WVhen the contact arin F reaches the connection terminals ofthe line,

the switching apparatus of which has been operated as'above described, a circuit will be closed by the contact device I and the j connection terminal a? from the battery e 'also energizes the magnet G, which draws down and locks thecontact arm F with the contact devices I, I 1 I in contact respectively with the connection terminals a 4.1 a a. The closure of the circuit through Til the relay 1; causes it to attract its armature opening at the rear contact thereof, the normal connection to battery of theili nbsl ofall otthe telephone lines through the magnet .1 of the finder device associated with the first connecting circuit and closing at the front cont-act thereof a substitute connection to battery torsuch lines through the conductor-43 and the magnet M of the finder device associated with the next or asubsequen one of said connecting circuits. By this means, immediately upon thetaking for use of the first connecting circuit, all the lines, with the exception of" the first calling line, which havefbeen to this time' normally associated with the stconnecting circuit are transferred from association with suchconnecting circuit into association with a second connecting circuit, and

' the limb 110i each of such transferred lines will be, until the'first connecting circuit is again idle, connected with the magnet W2 0i the second connecting circuit, and upon the ailing of a second line the magnet ill of the second connecting circuit will be operated similarly to the operation above described oi the magnet M or" the first connecting circuit. Such second calling line will be, therefore, automatically connected to the second connecting circuit by an operation of the finder apparatus associated therewith similar to that above described with relation to the first connecting circuit.

llpon the drawing down of the contact aria F a circuit is established from the bat tery e throughconductor 6 and relay whence it divid'esint o' two paths, the one through the relay g,couductor 7, back cou-- tact and arniature i oi? the relay 2', relay contact device .1, limb connection terminal a, of the telephone line, switch b-to ground and back to battery; and the other through relay Z2, conductor 8, back contact and armatuie 2' of the relay 2', relay a, con.-

tact device 1?, connection terminal (4 the limb '2 or" the telephone line, switch 6 to ground and back to battery.

The energizatien oi' the relay f by the closure of the circuit described attracts its armature and momentarily closes a circuit from the battery 6 through relay m, mag- -n ct G, conductors 10 and 11, armature and front contact of th relay f, conductor 12, conductor 13, conductor 16, armature and back contact otthe relay 1, conductor 17. back contact 72 armature p of the relay p, arinatur and each contact of the relay 0,

conductors UK and l t, magnet M to groun cl and back to battert The establishment of this circuit energ i: the magnet M but at most iminediately upon the establishment of this circuit, the energization of the relay r stablishes a 'circuit from the battery- 0 through the conductors 10, ll, 12, 13, back contact and armature g of the relay conductor 4iO, {tI'l11Etl3llI6 and front contact of the relay 5 con-:lnctor 15, reia 7", which may be made slightly sluggish in its attractive movement) to-gro d and back to battery. This energizes the y which. opens the original energizing circuit of the in gnct hi v fhe magnet M however, having been inc-- menta'rily energized by this original circuit, has riitlidra an the stop-arm L i" stop relation to the clock w'orlr mechanism driving the selector arm T Th initial movement of the arm F and the shaft E upon which it is mounted has also moved the wheels R, and T from their normal position and has ed the contacts R and R S and S and and T? The closure ot the contacts 55-. S at this time is ineiiective, owing to the retracted position of the armature 3'1 .ot the relay 3), is for the purpose of returning the sol to normal after conversation has cease in or". any abnormaloperation o Llin'l r-arni F the apparatus associa avith, resulting in the deenergi ition lVith circuit established 'h the contacts R R ous that if at any timethe magnet we should tor The closure of the contacts R 11- it will be obvibe decnei'gizeol a circuitwill be established rill be maintained until the wheel R is again in its normal position and the selector arm in its normal position at which time the contact spring R on entering the depression in the periphery of the wheel R will open the circuit and bring the selector to arstop,

In the ordinary operation of the system it is necessary, at thistime, that is upon the momentary closure of the original operating circuit to the magnetMF, to consider only the contacts T and T which, immediately upon the st'r'novement of the selector, have closed a circuit for the magnet M in substitution for the original circuit, such circuit being from the battery 6 through conductors i0, 11, 12 13, relay 0, armature p and back contact 19 of the relay 1), contact T contact T conductor H, magnet M to ground and back to battery. This circuit will be maintained until the contact spring T again enters the depression in the periphery of the wheel T, during which-time the selector will 7 have passed over the connection terminals or ten lines and will have been brought from its normal or'false zero position into its true zero position and is now ready for selection. At the same time the relay 0 energized by the closure of this circuit has, by the attrac- 'tion. of its armature, maintained the original energizing circuit of the magnet M open allowing itto close again only upon the opening of the contacts T, T at which time it is open at the relay 1". i

A further result of the drawing down of the a] in F by the energization of the maglet G andthe energization of the relay f has been the closure of the circuit from battery ,0 through conductors 10, 11, armature and front contact of the relay f, conductor 12,

contact I, connection terminal a*, relay d to ground aIfd back to battery. The closureof this circuit has energized the relay (Z which thereupon opens the circuits of the co clusters 3 and at, at its armatures d d .iectively, the opening of the circuit of ii ie condiictor l resulting in the deenergiza- =f the relay Z, which opens the original gizing circuit of the magnet G and the re ay m, but since the various circuits closed by the operation of the armature of the relay also include. the magnet G and the relay an they will both remain in energized condition. The opening of the conductor 3 by the relay (Z results in the preventlon oi the eiiergization of the magnet M of the finder apparatus associated with the second connecting circuit by the ground placed upon the limb 1 of the line A as previously indicated and hereinafter referred to which would otherwise occur.

The apparatus associated with the first connecting circuit and now associated with the calling line A is at this time in readiness for-selective operation by thesubscriber at the substation of the line A. For the purpose of illustration it will be assumed that the number of the line B, withwhich connection is desired, is 57. It will, therefore, be necessary for the subscriber A to step the selector arinF forward to the 517th line from the true zero position of-the arm F of the'selector.. This will be LGCOIDPllSllQCl by first stepping the arm F forward five long steps from the true zero position under for the subscriber. A to'properly manipulate the switches b andv 11 p His first act is to five tin'ies successively open and close, the

switch Z). The first opening of the circuit through the switch 6 has caused the deenergization. of the relay g which in turn by the relay "r has closed a circuit from the battery conductor 17, back contact 10? and armature p of relay-p,:.armatureand back contact of'the relay 0, conductors'li and 14, mag net M to ground and back to battery; .The energization of the magnet h by this circuit has again'startedthe movement of the con tact arm F and the movement of the wheel T with the contact arni F in'in'iediately closes the circuit through the contacts T T hereinbefore described to maintain the magnet M energized until the contact spring T again rests iii the depression upon the periphery of the wheelT, in which time the selector arm F has passedovor thecoi necttion terminals of ten lines, the relay 0 in the n'ieanwhile maintaining the original" energizing circuit of the iiiiignet M ope Iii-the meanwhile also the subscriber has again closed the switch 3) onergizingthe relay 9 over the saniecirciiit as before, which in turn again energizes the relay 1* as before 7 The contact arm F will, there,

the connection tei'ininals'ot ten'lines have been traversed. The. subscriber A will,

Each subsequent i turn by such deenergization closes a circuit from the batterye through conductors 10, 11, 12 and 18, armature and back contact of the relay is, conductor 19, relay 9, relay 1; to The closure this relay, which draws up its armatures and closes for itself a lockingicircuit' from bat tery-e t'hrough the conductors 10, 11, 12, 13

and 23*,armature g and front contact 9 of the relay 9, conductor 44, relay q, conductor 19, relay 7 to ground and back to battery. This locking circuit willthereupon maintain relays g and p energized, subject only to the control ofthe relay 7', which in turn will be maintained'energized until the energization of the relays s and e'.

The retraction of the armature of the relay I; by the opening of the switch 6 has opened the circuit to the relay 6' heretofore established by the energization of the relays f and 7': from the battery'c, conductors 10, ll, l2, l8 and 20, relay t to ground and back to battery' The opening of this circuit deenergizes the relay 6' which permits the retraction of its armature and closes circuit from the battery e'through conductors 10, 11, 12, 13 and 2l,'armature and back contact of the rela t conductor 22 front conclosure of these tact p and armature p of the relay 7?, which is now energized, armature and back contact of the relay 0, conductor 17, conductor 14, magnet M to ground and back to battery. The euergization of the magnet M again allows the selector arm to move forwardly, moving therewith the wheels S and T. This movement ofthe wheels S and T again causes the closure of the contacts T and T and S and S but since the relay 3) is now energized and the contact 79 is no longer in contact with the armature the closure of the contacts T T is no longer effective and vattention need only be given tothe closure of the contacts S and S The contacts has established a circuit from the battery'e through conductors 10, 11,12, 13, relay 0, armature p and front contact p of relay 2), conductoru24, contacts S and S conductor 1%, magnet M to ground and back to battery; This circuit will be maintained until the contact spring S rests in the next succeeding depression in the periphery of the wheel S, during which movement of the wheels the contact arm F is, moved from over the connection termirelay 8,

nals of the line 50 to adjacentv the connection terminals of the line 51. Meanwhile the subscriber A has again closed the switch 6 which has again energized the relay, A through the circuit heretofore described, which in turn has ain energized the relay through the OllClilt heretofore described, which in drawing up its armature has openedthe circuit to the magnet M through the conductor 22' and the front contact p and the arn'iature 20? above docribed.

The subscriber Athen continues to open and close the switch 5 until he has done so seven times in all, each openin of the circuit causing the selector an F to take one short step under the control of the contactins 'ing wheel S and thereby bringing it adj? ent the connection terminals 6 b 1 2'2 or the desired line No. 57, each such short step being accomplished similarly to the first such short stop as above described.

The subscriber it having now fully as ccmplished selection his next act is to maintain the switch (3 closed and open the switch 6. The opening of the circuit hcreinbefore described through the switch .7) again causes deenergization of the relay g, which allows its arir-iturc to retract and thereby closes circuit from the battery e'through' the con ductors l0 and 35, armature and front conact of relay a, which is now closed due to the closure of the switch conductor 4-0, 2', back contact and armature of the i c g, conductor 40, armature and front contact of relay 9' primary winding k of the induction coil 7t, conductor '31, contact device U of the selector arm F ronnection terminal 6* associated with the line l3, conductor 33, armature and back contact of the relay V], which is deenergized if the line desired is idle, to ground andback to battery. Uponthe closure of this circuit, which, as will be noted, will only occur if the guard-relay \V is deenergized, the relays s and will be energized and attract their armatures. The drawing up of the armature 2' of the relay i closes a locking circuit for such relay from the battery 6 through conductors ll) and 335, armature and front contact of the relay a, relay a, relay 2', a "mature i and front contz-ictc' of the relay 2', conductor magnet G of the selector switch, contact d vice U upon the contact F connection terminal I), conductor 3%, magnet TV to ground and back to battery. This circuit not only provides alockingccircnit for the relay 2', but also serves to energize the magnet G and the guardrelay W. The relay W thereupon draws up its armature and removes the normal ground connection from the conductor 38 and the" connection terminal 5* and substitutes therefor a busyback X connected-to said conductor 83. and terminal Z1 by the condenser Y and conductor 45 for purposes hereinafter to be described.

At the same time simultaneously with the energization of the relay V, the magnet G has been energized, drawn down the arm F and locked it in position with the tour terminals U, U U ll, each in coi'itact with its respective cooperatingconnection terminals 5 7, 2; 7), 7i otthe desired line B.

It will'at this point he noted that in the selector switch the contact devices I and U make contact at all times with. the connection terminals 5* and b respectively of the set of: terminals over which the contact arm F rests and in the movement of the arm trail over the several connection ter minals b and 5 serving in this manner not only to complete the test circuit and holding circuit through such terminals when selection is completedbut also to hold the arm F in its normally retracted position.

The cnergization of the relay i has also attractedits armatures v1 and i brealri the circuit heretofore maintained through the relays is, g and but immediately connecting the limbs of the telephone line to the conductors and 30 by the respective front contacts 71, A. circuit thereupon established from battery 6*". conductor I'll), front contac a and armature of the relay i, relay a contact device 1*, connection terminal limb 2 of the telephone line A. switch 6 to ground and back to'ha-ttery. This circuit will maintain the relay a ei'lergized, although the original energizingcircuit tor this relay has been broken.

The enci .zation ot the relay 5* by both the original energizing circuit and the locking circuit ot the relay 2' has, will be not cl, established an alternative energizing circuit for the relay (Z from the battery 6, vonductor 1.0, conductor 38, armature and trout contact of the relay 8, conductor 36, contact device 1, connection terminal a rel; (Z to ground and back to battery, wnich circuit, since it has been established before the deenergization of the relay 7, will prevent at this time any release of the relay (.5.

Immediately upon the energization of the 'magnet (l which has resulted in the conne 'tion ot the limbs 'l and :2 of the telephone line I? to the ccmtact derives U and U 0% the switch arm ii through the connection terminals Z and a ringing current will pass over the telephone line B from the.

source of ringii'ig current V, back contact contact device U, connection terminal 71 limb 1 of the telephone line B, the condenser and ringer at the substation of such ductor 26 armature a and back contact thereot of the relay to back to the source oi current. 'This current will ring the bell and armature a of the relay a, conductor of the called substation and such circuit will be maintained until the relay u is energized by a further act of the calling subscriber.

The next act of the subscriber A by which the connection of his line to the line desired completed to reunite his receiv r the relay a, which has" alreadyibeen main tainerl energized over a portion of this circuit, energizes the relay j and causes it to attract its armature This closes a circuit from the battery 6 relay a, conductor 32, front contact and armature of the relay to ground and back to battery. The closure wircuit energizes the relay a which -sarmature, cutting off the source currentirom the conductors 25 and :6 connecting the conifluctors EZY and, 8 to the couductors25 and 26,'respectiyely, thereby completing the i the sulistation A to the substation B, l circuitincluding the reso'ective wi11d e romnionbattery c 'as usual. All that is now required. to accomplish ccmrersation between t telephone line A the transmitter and v ion of such lineglimb (it the induction coil i nilicated acent.

no two substations the removal of the receiver at the substation- B from its hook, which establishes'a metallic circuit tromthe battery 0', conductor 28, front contact and armature a of the cording to stau'daalcommon battery prac-.

tice. Similarly the substation A is also supplied withtalking battery ove'r the metallic circuit hcreinbetore described which circuit includes the relay a and therelay j, thebattery. supply to this station being also according to standard common battery practice.

promptly the subscriber A; may again 'sig' nalthe subscriber by closing one of the switches 72 or Z). This places a ground upon transmission circuit It the subscriber B should tail to respond the telephone line thereby shunting the relay j which allows its armature to retract, opening the energizing circuit of the relay u. The deenergization of the relay it permits its armatures a and a to retract and the ringing circuit hereinbefore described is again established. After a suitable period the subscriber A will again cut oil the ringing current and reestablish the transmission circuit complete by opening the switch 5 or b which has been. closed again energizing in a manner heretofore described the relays j and 'n.

As soon as conversation is completed'the subscribers replace their receivers upon their hooks.- The hanging up of the receiver at the substation B does not in any way affect the apparatusby which the circuit is 001m pleted and should the subscriber B for any reason hang up his receiver before the conversation is completed the subscriber A may again signal him in a manner that has been heretofore described, the entire connection being wholly under the control of the sub scriber A at the calling station. When however, the subscriber atthe calling sta tion A replaces his receiver upon the hook the relays j and n are both deenergized. The armature of the relay n in falling back breaksthe energizing circuits of the relays m, .8, 2' and W and of the magnets G and G furthermore, the deenergization of the relay .9 has opened the energizing circuit of the relay (Z, causing it to retractits armatures, the relay f having-been deenergized upon the initial energization of the relay 2' and now being maintained deenergized on account of the opening of the various cir cuits at the calling substation.

The deenergization of the relay d has again restored the line connections of the telephone line A to normal, thereby coinpleting again the local circuits through the conductors 3 and 4:.

The deenergization of the magnets G and G has allowed the respective arms F and F to retract and the connection of the con tact devices I, I and I with the connection terminals (4 a and a respectively and the contact devices U and U with the connection terminals 5 and 1- respectively, is broken.

The finder device, in which the movement of the arm need bear no definite relation to the number of the line with which it is de sired to make connection therethrough', need not, therefore, be returned to nom nal and, in fact, does not have any normal position, but rests in the position where it was last used, the contact devices of the line cooperating with the connection terminals with the limbs of the line, however, being out of con tact with such connection terminals. This construction is possible for the reason that the contact arm F in its movement to find a .tracted.

the selector arm around to the connectlon' calling'line sweeps over the terminals ofall the lines until it finds the line which is calling, at which point, due to theenergization of the relay Z as hereinbefore described, it is stopped.

With regard to the selector switch on the contrary, it is necessary,.prior to a second connection over the connecting circuit illustrated, that the selector arm Fbereturned to its normal or false-zero position. This is readily accomplished, however, by the establishment of an energizing circuit for the stop relay M due to the deenergizationof the magneton and the off-normal position of the contact-making wheel B. This circuit may be traced from the battery 6, armature and back contact of the relay m, conductor 39, contacts R and R, stop magnet M, to ground and back to battery. The magnet MI- having been: energized the olockwork mechanism will bev free to move to drive the selector until it again reaches its normal or false-zero position, in which posi tion the contact spring R will again enter the depression in the periphery of thecontact wheel It, thereby breaking the energi- Zing circuit of the magnet M, which by its deenergization prevents the further operation of the clock-work and stops the se lector. l

The deenergization of the relays 2' and have restored normal connections of the'connecting circuit and of the source of ringin current to the conductors 25 and 26. f will, however, be .noted that no false signal will be given the substation B on account of the immediate deenergization of the mag net Gr.

it will further be noted that the relays g and j) which were locked up in the interval between the tens and units selection were deenergized by the deenergization of the relay f at the time of the energization of the relay i. It will be apparent, therefore, that all the apparatus is again restored to normal ready for a second call, a plurality of telephonelines being again associated with the first connecting circuit and-its finder device by the retraction of the armature of the relay n, the circuit to which relay was broken by the retraction of the armature of the relay m.

Let us assume no that the subscriber B, with whom the subscriber A desires to obtain connection, has been already engaged in conversation in which case the relay V is maintained energized with its armature at lhe subscriber A having stepped terminals of the line desired, in this instance the telephone line B,-he opens the switch 7) and. the circuit is closed from the battery '6,

. relay g, conductor 40, armature g and front contact thereof of the relay 9, primary Winding h of the induction coil h, conductor 31, contact device U 2 of the selector arm F, connection terminal I), conductor 33, armature and front contact of the relay W', condenser Y, conductor 45, busy-back X to ground and back to battery. ,Owing to the presence in this circuit of the condenser Y no current from battery 6 will pass and the relays s and i will remain inert. The busy tone, however, on account of its alternting character will pass readily over this circuit, and in passing through the winding h of the induction coil it will introduce a similar and characteristic tone in the winding h of the induction coil from which it will be ner restore the apparatus to normal.

transmitted to the callin ubscribed over a 1 of the telephone line A, receiver and trans mitter of the substantion A, when the subscribed removes his receiver from the hook,

limb 2 of the telephone line, connection terminal a2, contact device I of the'finder arm F, relay n, armature i and back contact thereof of the relay i, conductor 8, relay in, relay 9 and back to the winding h of the induction coil h. The subscriber A upon hearing thebusy tone in his receiver will be immediately aware that the line selected jis busy and will thereupon replace his receiver upon the hook, thereby, since both the switches 72 and Z) are at'this time open, restoring, as has been heretofore described, his entire apparatus to another call. 7

In this connection it will be noted that the busy test circuit, both the circuit including the primary winding of the induction coil 75 and the secondary winding of such induction coil, will be maintained so long as the selected line remains busy and the subscriber at the calling line does not in the usual man By this means the calling subscriber cannot fail to receive either the busy signal or the connection desired, should the line B become idle in the midst of the test.

If during the use of the connecting circuit, shown in full in the diagram in Figs. 6 and 7, by the subscribers line 1' a second subscriber should desire a connection, the closure of the switches 0 and Z) by such second subscriber at his substation will estab lish acircuit from the ground at such substation over the limb 1 of his line through the armature and back contact of his cut-- off relay (notshown), the armature and normal and ready for to the operation hereinbefore described in establlshing connection betwen the sub- To the extreme left of scribers A and B. Fig. 6 is diagrammatically shown the relation of the limb 1 to various telephone lines of the apparatus shown. It will be obvious thatshould both the first and second connecting circuits be busy the two relays "2) would be energized and the limb 1 of the various lines would then be connected through. the armatures and front contacts of both of the relays o to the magnet M of a further COl'l". necting circuit.

It will be readily understoodthat the con nections of each line in eachof thefinder devices will be simple multiples and that the 1 connections to eacl line in each of the selector devices will be simple multiples, as indi-- cated by the short branch wires leading from each of the fixed terminals of the switches shown in the drawings. Furthermore, the line terminals. of each line are multiples in the first two connection terminals shown a, a? and 5 ,3 of each of the switches for the finder or selector; terminals on the line finders and line connectors for each line are connected in multi ple, as indicated. in Figs. 6 and 7 In this manner each connecting circuit is tdapted'to interconnect any two of the lines of the exchange.

e 1 a i t e a 1 the (rim iercin S "lOlVIl, llOI' Are any 0 Lib.

eatures thereof; but the invention as a whole or any of the features thereof, as defined by the claims, may be employed ac-' cording to the engineering or traflic require ments of any particular case. 7

Having described my invention, what I claim and desire to secure by Letters Patent of the United States is I i 1. In a telephone exchangesystem, the combination with telephone lines extending to two sets of connection terminals, of a contact carrying arm associated with each said set of terminals, a connectingcircuit con necting said arms, mechanism adapted when released to move said arms adjacent to the terminals of a calling; and a called line,

And .thelowermost While I have shown and referred to va-- respectively, magnets adapted whenener gized to release said mechanisms, magnets adapted when energized to draw said arms ing in groups of connection terminals, a

finder device associated with each said group, a connecting circuit connected to each said finder device, an operating electromagnetic mechanism for said finder device i to select the terminals of a line, a second electromagnetic electromagnetic -mechanism adapted to bringsaidfinder device into contact with such terminals, switching apparatus associated with each said line, circuitsfor said electromagnetic mechanisms controlled over said lines by said switching apparatus, a relay adapted to control the connection of the lines with said operating electromagnetic mechanism associated with one finder device and to transfer such connection to the operating electromagnetic mechanism of another finder devlce, and a circuit for said relay controlled vby the second mentioned electromagnetic mechanism.

3. In atelephone exchange system, the

combination with a plurality of telephone lines extending to terminals, of an automatic switching apparatus adapted to select the terminals of a line, holding mechanism to hold said switching apparatus in selective position, electromagnetic mechanism controlling said holding mechanism, a

circuit for said electromagnetic mechanism including a source of current and a portion of each sa1d l1ne, a swltchpassociated with each sa1d line controlling sa1d circuit, a

connecting circuit connected to said automatic switching apparatus, a relay adapted tocontrol the completion of the connection of said switching apparatus with the contact terminals of a selected line, a circuit for said relayadapted to be completed over a portion of each of said lines, and a second switch adapted to complete said circuit;

4. In a telephone exchange system, the combination with telephone lines extending to a plurality of groups of connection terminals, of switching apparatus associated with each said group, power mechanism adapted to operate each saidswitching apparatus to select terminals of a line, a stop mechanism normally preventing the movement of said switching apparatus, electromagnetic mechanism individual to each said stop mechanism for controlling said stop mechanism, an actuating circuit for said mechanisms including a source of current and a portion ofieach said telephone line, a switch associated with each said line controlling said circuit and mechanism adapted to connect said circuit with said electromagnetic mechanisms in succession, said mechanism being operated in the response of each said switching apparatus to a call to transfer said actuating circuit to the electromagnetic mechanism of the next switching apparatus.

5. In a telephone exchange system, the combination with telephone lines extending to groups of terminals, switching apparatus associated with each said group, a connect ing circuit connected to each said switching apparatus adapted to extend the circuit or said lines, electromagnetic mechanism for moving said switching apparatus over the associated group of terminals, electromagnetic mechanism adapted to arrest the movement of said switching apparatus and cause it to complete connection between a connecting circuit and one of said lines, a switch associated with each said line, a source of current, a circuit for said electromagnetic mechanisms including said source of current and the switch associated with the line I the circuit of which is to be extended, a cir cuit for said electromagnetic mechanisms completed to each line in registering contacts or" its connection terminals and said switching apparatus, a cut-off relay for each line adapted to disconnect from the line thec1rcuits and mechanism for operating said switching apparatus, and a circuit for said relay closed by the connection to the line with which the relay is associated of a connecting circuit by means of said switching apparatus.

'6. In a telephone exchange system, combination with power mechanism, of a magnetic clutch controlling said power mechanism, a. movable part adapted to'be rotated by said power mechanism, a circuit for said magnetic clutch, a switchadapted to close said circuit initially-tooperate said clutch, and contacts closed by said movable part in its movement to maintain said circuit closed for a predetermined period of movement independent of said switch.-

7. In a telephone exchange system, the combination with a switching device adapted to make tens and units selection, of a power apparatus for driving said switching device, an electromagnetic device controlling said power apparatus, a contact wheel, a circuit closer operated by said contact wheel to control the circuit through said electromagnetic device at intervals corresponding to the spaces of units selec- 't-ion, a second circuit closer operated by said contact wheel to control the circuit through said electromagnetic device at intervals corresponding to the spaces of tens selection, a switch adapted momentarily to op-- the I cause the movement of. said combination with telephone lines extend= ing to connection terminals, a connecting circuit, anautomaticselector switch adaptedfto unite said connecting circuit with the connection terminals of any of said lines.

said switch having a contact device adapted to move over said connection terminals in sequence and maintained normally and. during its 'Il'lOVGHlQllil out of contact therewith, alternative controlling devices adapted to switch over the contacts oi. ten lines or ovc the contacts of one line 1 for each actuatio means controlled over a calling line to said connecting circuit for actuating said controlling devices the required number of times to move said contact device to select the connection terminals of any line, an electromagnet, an armature therefor secured to said contactdevice, said. electromagnet when energized oeing adapted to move said contactrdevice into engagement with the connection terminals of the selected line, and circuit tor said electromagnet controlled from the calling line.

,10.- .ln "telephone exchange system, the combination; with telephone lines extendin to connection terminals, of switching apparatus adapted to move over and malre contact with said connection terminals, power mcchanism operating said switching apparatus, anelectromagnet controlling said power mechanism and normally preventing the movement of said switching apparatus, alternative controlling. circuits tor said elec tromagnet, circuit controlling devices to regulate the period during which, said electromagnet-"shall continue energized to permit the movement of said switching apparatus said circuit controllingdevices being included onein each of said circuits and oporated in the movement of said switching apparatus, and switching mechanism adapted to bring said controlling circuits alteruately into operative relation with said switching apparatus.

115111 a telephone exchange system, the combination with a selector arm, of a magnet, and mechanism controlled thereby for 7 moving said arm, a circuit for said magnet,

controlling devices therefor, each said device when actuated maintaining said circuit completed a certain predetermined interval to permit said selector arm to move a predetermined distance, and means adapted to bring said controlling devices alternately into operative relation with the circult of said magnet. i

12. In a telephone exchange system, the

combination with a group of connection tor-- minals, of a selector arm adapted to move I over said terminals, mechanism for moving said arm, alternative controlling mechanism for causing said arm to move in long and short steps, and means" adapted to bring.

said controlling mechanisms into operative relation to said arm. I v c 13. In a telephone exchange system, the combination with telephone lines extending. to connection terminals of a selector arm adapted to move over and make contact 30 with said connection terminals, mechanism for moving said arm, electromagneticmech anism adapted to control the starting and stopping of said arm, alternately controlling-circuits for said electromagnetic mach-.7

anism, including contact devices operated in the movement of said arm, to control said electromagnetic mechanism to allow said contact arm to advance over a certain number of said connection terminals, the num- 99' ber of said connection terminals over which said arm may advance differing for the different controlling circuits, y I

14:. In a telephone exchange system, the

combination with telephone lines extending 95,

to a group of connection terminals, of a tinder device adapted to rotateover said terminals, a connecting circuit terminating in contacts upon said device, a magnet M and mechanism "controlled thereb the rotation of said device, a circuit for said magnet adapted to be controlled over any one of said lines, a terminal a associated with the connection terminals of: each line and connected with one of the limbs of said 7 line, a contact brush carriedby said device, and adapted in the movementithereofto trail over the terminal'o of said lines, a conductor including a magnet l and a source of current connected with said brush, a key associated with each line adapted as the con- 1 tact brush of said device engages theterminal a of such line to complete a circuit for the magnet Z, a magnet G adapted when energized to move said device to bring the brushes carried thereby into engagement with the line whose key has beenoperated, and a circuit for said magnet. G controlled by said magnet Z.

15. In a telephone exchange system, the

combination with telephone lines each extending to two groups ofconnection terminals, a switching device adapted to sweep over each said groups of terminals, a connecting circuit uniting said switching .de-

vices, electromagnets M, G adapted to bring one of said switching devices into circuit with the terminals of any line, circuits for said magnets adapted to be controlled over each line, a magnet M? and mechanism concontrolling trolled thereby for operating the other switching device, a relay 9 in a branch of said connecting circuit leading to a grounded source of current, a key associated with each line adapted to ground the limb of the "magnet G adapted to move said other switching device into engagement with the terminals of any. desired line, and acircuit for said magnet controlled over the calling line. i f r r 16, In a telephone exchange system, the combination withtelephone lines extending to groups of connection terminals, of a :inder arm associated with one oi? said groups, a selector arm associated with another of said groups, a' connecting circuit uniting said arms, electromagnets 7i and G controlling the connection of the finder arm with the connection terminals of the several lines,

circuits for said magnets adapted to be controlled over any telephone line, a relay g connected with a source of current in a ground branch from said connecting circuit, means associated with each line for intermittently grounding the limb ot the line'connee-ted through said connecting circuit with said ground branch, a magnet M controlling the movement of said selector arm, a

circuit for said magnet adapted to be completed by said relay 9, a partniounted to rotate with the selector arm, said part hav ing depressions upon its periphery at predetermined intervals, spring bearing upon the periphery ofsaid part, said spring luving a'contact from which it is separated when resting in any one of said depressions, a locking circuit for said magnet M closed by said part when rotated during the interval that the contact spring is passing from one depression to the next; whereby by one manipulation of the substation key said selector arm may be moved over the connection terminals of a predetermined number of lines, a magnet G adapted to draw said selector arm into engagement with theterininals of any desired line, and a circuit for said magnet G controlled 'overa calling '17. In a tele hone eirchane e s stem the combination with telephone lines extends ing to two groups otconnecti'on terminals, of finder-arm associated with one said groups, a selector arm associated with the V tlier said group, a connecting circuituniting said arms, a pair of electromagnets controlling'the connection of the finder arm with the terminals of any line, circuits forsaid magnets controlled over any line in calling,

electromagnetic mechanism controlling thev connection of the selector arm with the terminals of anyline called, circuits for said mechanism controlled over the calling line, a source oi ringing current, an electromagnetic switch controlling the connection of said source with a called line, and a circuit for said switch controlled over the calling line. r 7

18. In a telephone exchange system, the combination with telephone lines extending to two groupsot connection terminals, of a finder arm associated with one of said groups, a selector arm associated with the other of said groups, a connecting circuit uniting said arms, electromagnets M and G controlling'the connection of the selector arm. with the terminals of any called line, circuits For said magnets controlled over the calling line, a relay n, armatures and their front contacts of said relay included in said connectingcircuit, said armatures being connected directly with contacts upon said selector arm, a source of ringing current, the poles whereof are connected with the back contacts of said armatures, whereby when the selector arm makes contact with the terminals of a called line ringing current is automatically applied thereto, a battery in bridge of said connect ing circuit, a relay j included in said con- ;necting circuit responsive to the switching complete the circuit thereof.

19. in a telephone exchange system, the combination with a finder device comprising a terminal support... of telephonelines ter iilillatlll in connection terminals carried by said support, an arm carrying contact devices, power mechanism for rotating said arm adjacent said connection terminals, a step device noriiia-lly pre enting the operation of said mechanism, a magnet controlling said stop device, and a magnet for which said iontact arm forms the armature adapted to attract said arm and draw its contacts down upon the terminals of any desired line. 7 v

20. In a telephone exchange system, the combination with telephone lines extending to groups of connection terminals,ot a contact arm'tor each group, a connecting circuit associated with each arm, mechanism adapted to move each arm over the connection terminals of each group, a magnet controlling each of said mechanisms a con- 7 group, a second magnet adapted to draw the contact arm 'agamst the terminals oi any calling line, a circuit for said second niagmentioned magnet of the second group or net cdntrolled over the calling line, and means actuatedvin the completion ot said circuit adapted to connect said conductors of each of the remaining lines with the first [1 connection terminals, whereby it the contact armin the first group is employed in maklng connection with the calling line the next calling line will be selected by the contact arm of the second group the contact cuit of said magnet, a second magnet for each said contact arm adapted to complete the connection between said contact arm and the terminals of any calling line, a circuit for said second magnet, switching apparatus associated with each line adapted to complete said circuit as the contact arm becomes adjacent the terminals of such line, a relay m in said circuit and a relay o in a circuit controlled bv said relay m, said relayo being adapter when energized to dis onnect the said conductors leading from the several lines remaining inert from the said first magnet ot the finder arm in use and to connect said conductors with said first magnet of the next group of connection terminals.

22. In a telephone exchange system, the combination with telephone lines extending to two groups of connection terminals, a finder arm associated with one of said groups, a selector arm associated with the other of said. groups, a connecting circuit adapted to unite said arms, a pair of electromagnets adapted to bring said finder arm into connection with the terminals of; any calling line, a pair ofelectromagnets adapted to bring said selector arm into contact with anycalled line. a pair of relays adapted to be associated with said connecting circuit and controlling the operation of said electromagnets associated with the selector arm,

a second pair of relays adapted to disconnect said controlling relays from said connecting circuit, and switching apparatus associated with any calling line controlling circuits for said relays in proper sequence.

, 23. In a telephone exchange system, the combination with telephone lines extending to two' groups of 'connect1on terminals, a

connecting circuit, a finder device connected to one end of said connecting circuit and associated with one said groups, electromagnetic'mechanism for moving said arm into contact with the connection terminals the other end of said connecting circuit and associated with the second said group of connection terminals, a magnet controlling the movement of said selector armover the con- '70 of a calling line and adapted to be controlled over such line, a selector arm connected with ncction terminals of such group, alternative controlling circuits for said magnet adapted to be operated over the, calling line and including contact devices operated in the movement of said selector arm, said contact devices being arrangedwith relation to said selector arm to control said magnetto 'allow said selector arm to advance over a predetermined number of said connection ter minals, said predeterminednumber difiering for the different controlling circuits, where by said selector arm maybe advanced to the terminals of any desired line, a relayin: a circuit adapted to be controlled overrthc calling line, a circuit for said magnet controlled by said. relay upon the termination of conversation between two connected lines to return said selector arm to normal, and a contact device includedin said last mentioned circuit and actuated upon the return of said selector arm to normal to open the circuit of said magnet. 1

24. In a telephone exchangesystem, the combination with an escapement, of a shaft,

power mechanism 'for driving said shaft, an

electromagnetic clutch, controlling said power mechanism, a movable part carried by said shaft, a circuit -for said electromagnetic clutch, a switch adapted to close'saidcircuit. initially to operate said clutch, and acontact spring and its anvil associated with said movable part, said part having a number of depressions in its periphery located aspredetermined distance apart, the end of said spring normally resting in one of said depressions out of contact with its anvil, said spring uponthe movement of said part being forced out of said depression into, en-- gagement with its anvil to maintain the circuit'of said clutch closed independentof said switch until it enters the next depressionv upon said part.

25. In a telephone exchange system, the combination with telephone lines extending to connection terminals, of a contact carry ing arm adapted to sweep over said terminals, a contact on said arm being normally and during its advance out of engagement with said connection terminals, power mechanism for moving said arm, an electromagnet adapted to start said mechanism,

an eletromagnet adapted to stop said arm when it s adjacent the connection terminals of a calling line, said second electr'omagnet

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