US1232338A - Automatic telephone-exchange system. - Google Patents

Description

1. w. LAT-TlG ac. L. eoonnum. AUTOMATIC TELEPHONE EXCHANGE SYSIEM.

.. APPLICATION man JAN. 1a. was.

' Patented July 3, 1917.

' n SHEETS-SHEET 1.

1. w; LATTIG & c. L. eoonnum. AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED um. 1a. was. I 1,232,338. Patented 11115 3, 1917.

n SHEETS-SHEET a.

J; W. LATTIG & C. L. GOODRUM.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

r APPLICATION FILED MN. l8. I906- 1,232,338. Patented July 3,1917,

' 1| SHEETS-SHIN 5.

W6 in wow J. W. LATTIG & C. L. GOODRUM. AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

umcmou FILED JAN. 18. 1906. r

Patented July 3, 1917.

ll SHEETS-SHEET 6.

l; W. LATTIG & C. L. GOODRUM.

AUTOMATIC reuzruouz EXCHANGE SYSTEM.

APPLICATION FILED JAN-13.1905. 1,232,338, Patented July 3, 1917.

ll SHEETS-SHEET I.

PatentedJuly 3, 1917.

I1 shins-sun a.

A PP LICATION FILED JAN. l8. I906.

- AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

J. W.'LATTIG 6: C L. GOODRUM. AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JAN. 18. 1906 7 1,232,338. Patented July 3, 1917.

n SHEETS-S'HEET 9.

119i humus J. W. LA TTIG& C. L. GO ODRUM. AUTOMATICTELEPHONIE' EXCHANGE SYSTEM.

APPLICATION FILED JAN- |a I905- 1,232,338. Patented July 3, 1917.

, H SHEETS-SflEET ID- shown,

J. W. LATTIG & C. L. GOODRUM. AUTOMATIC TELEPHONE EXCHANGE SYSTEM;

APH IFATION FILED JAN. 18. 906. 3,

I I SHEETS-SHEET II 'A TTORNE Yd UNITED swarms OF A'IHENS, GEORGIA, ASSIGNORS, BY'M r rnnr OFFICE.

JACOB WILLIAM LATTIG, OF ROCHESTER, NEW YORK, AND CHARLES LANE GOODR UM,

ESNE ASSIGNMENTS, TO WESTERN ELEGTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented July 3, 1917 ApplicationhledJanuary'iS,1908. Serie1No.2B6,885..

'1 '0 all whom itgmay concern Be it known [that we, ilaooc WILLIAM LAT- change systems, and. particularly what are known as automatic telephone exchange systems, and has for its object the m'iprorement thereof in the manner and-in regard to the features hereinafter set forth.

. Herctofore, most anton'iatic systems with which we are acquainted have provided what is commonly called a. first selector switch for each line. In some systems this first selector switch performed the function of actually selecting the tlumsends digit of the whole ll'Ull'llJOl' of the subscriber wanted,

and finding an idle trunk correspondingthereto; in other systems, including some oi? our own (lesi n, the first selector has been simplified an used merely for the purpose of selecting an idle trunk to another selector switch tln'ougliwhich the desired operation might be performed. The second of these methods has proved to be the better in practice,.the line switch then ceasing to be a trucfirst selector, and becoming what is ca lied an A switch, through which the line. calling is put upon a first selector. This, however. is only one step toward simplification; and in the present case we shall sct hirth the second ste by which the lines are not pro vided wit-1 any switcl'res, but mercy with terminals in what we shall call finders, there being number oflines calling at once. cent. of the :u-unhe-r =o:l"l-i nes is probably suflicient, .andin many cases a lower percentage of finders will snlliee.

Inconjunction with our finds-1" switches we use what we s'l-mll' term starters. the function oi which is to segregate each finder switch as it becomes busy, by nick-lug up a calling line,.a ,nd simultaneous y to render alctive'the nextfinder switch in order, thus only so many of thesefinders as are actually reqmr-edRtotake care ot the Ten per distributing traflic over a plurality M155 swi'tches.- By this means the first incomingcall is picked up. by. the firstidle finder. switch; the second incoming call is taken'up, by the next idle finder switch, and so ,on,; without interference. Each tinder switch constitutes the answering terminal for a trunk line leading to a first selector or A switch, and thence the connections'and cir-' cuits being the same as in our former e etems, to which more detailed reference will be made hereinafter. The present invention does not reside in the system of switches or circuits employed from the first selector on ward, but resides particularly in the-arrangement and circuit connections of the starter and tinder switches.- By our present invention each line is puivided with a relay which is operated when t the line calling becomes energized and ren clers active the controlling circuit of the first idle finder switch, passing thereto through i. certain contacts controlled by 'the starter switch. The. finder switch responds' by star-ti mg the starter switch, and nt-t-hc. sametime the starting circuit is altered so that so. the starting impulse reduced to lll'fllnfilitarry duration only. The starter switchmores one step, cuts off the finder then in operation from the. starting circuit, and puts the next idle finder thereon. The selected 85 tinder switch, in the meantime, inorcsaro uld until it finds the terminals of thc'linc cal l in'g, whereupon it stops and crmnects that line to a trunk passing to the first selector switch. At the close of the conversation, the subscriber in ha-i'iging up rcstor the finder switch, as well as all the sch-actor switches, by the some operation.

Referring ,to the (hr-airings, Figure l isaf. top plan. view oi a B or first selectm' 'switrlh' 1 Figs. 2', 3, -31.- and 5 are details thereof; l-i' is a :top' plan view of the (i or Conner. switch and Fig. 7' is a detail rib-u" of 1 banks; Figs. 8, .9, 1 0, 11 and l zure'continuing dia ra-ins showing respcelnechr the .ciriOO .cfi i-tslo' the starter switch A l'hn-lcr or A I switch, first selector or it swit-h, second selector or C switch,connector or G switcl and the lineapparatus; Figs. 8" kind 8*" :1, associated diagra'rnmatiq' views naanagt; plurality :of the finder switches 'i llustrat In these ligu'res three separate instrument circuits are 'shown served by four finder switches on each of which blank contacts are shown illustrating terminals of other circuits of .w11ich there would be upward of fifty, representing an equal number of lines greater than the num'-' ber of switches. View showing a separate starter switch and illustratin its operation in'connection with a group 0 finder switches. Referring to Fig. 1, E is a base plate of metal, rectangular in shape and divided along the line 0 of its upper end, leaving an upper rim e to form a ase for the contact banks F. Upon this base a row of socket contacts H are mounted in insulation, with which cooperate the contact terminals h mounted in a strip on the base E. These terminals 72. are used to complete the circuits from the cable in the racks to the magnets shown on the base E.

The contact banks F are formed as an arc of a circle subtended by an angle somewhat less than 180 degrees, and concentric with the center or axis 6 of the switch spindle. In the banks are the broad contacts 48, and the individual trunk contacts m, which will be pointed out hereafter in referring to the diagrams.

' Extending across the upper end of the plate E is a bridge 6* drilled'at its middle point to receive the coned end of the switch spindle 7). 'Directly in line with the o ening in the bridge a similar opening is V ormed serves to return the spindle to initial in the plate for the other end of the spindle. In a box secured around the foot end of this spindle is the coiled spring b9, which os1 tion when released, 'as hereinafter described. Upon the spindle are mounted the ratchet wheels 6 and I), the stop ratchet 'wheel '6, and" the wipers b b b These, and articularly the wipers, areinsula'ted. wiper hasan arc b ,extending around the spindle, and upon these arcs, which serve as collector rings or segments, rest the ends of contact springs I), carried in insulation on the right hand side of the bridge efl'as shown in Fig. 1, each springdiaving a'tail b for tie attachment of its circuit wire, an extension I) which receives the wiper when turned all theway around to clear it from the bank contacts and hold it in proper position for reengagement therefrom the switch.

with,this clearing being necessary when-the pla'te E and its attached'partsare removed;

To facilitate the removal and replacing of theplate in proper alinement with the bases of the "banks, we provide apairpfguide tongues e ,.attached to the plate 0. and overlying the plate E when in position. The bank as a whole is carried on four, posts pbest' shown in Figs; 3 and- 5, and each; bank of contacts is built up of insulating segments with the-contacts ra- Fig. 13 is'a diagrammatic.

body plate E.

dially interposed between them, the whole beingheld together by upper and lower segmental metal plates 1 secured by .throughbolts or screws f Cooperating with the ratchet teeth I) on the wheel 6* is the pawl 6 on a dog 6 ivoted in a yoke attached to the base-plate as shown inFigsLl, 2 and :3. The dog has a joint in the middle, and a spring nor many-tending to throw it up with the ratchet engaging, the teeth I). Cooperating with this ratchet to form an escapement is the armature lever I) of the magnet lVlflthis lever havingachisel edge to enter the teeth, and abar b to withdraw-the ratchet as the edge enters, by forcing up the tail Z) of the %pposite the ratchet the dog has a toe b" with which cooperates a hook on the end ofthe spring I) carried on the end of the armature lever .of the release magnet 'M When this armature is attracted, the ratchet 6 being up, the spring reaches up, the hook takes hold of the toe and-pulls down the dog, ermitting the spring Z) to return the sp1n 1e 6 and all its arms to zero position as shown in Fig. 1. x I

In order to step the-wheel Z around, the

pivoted at b and having an angle sto 1).

. armature of the magnet M carries apawl b coming a ainst a fixed stop 5 on the bridge *6 when t e magnet is deener ized as shown in Fig. 1. As the magnet T is energized,- its vertical lever is thrown tothe left, a pro ]ect1on on the lower part thereof comes against the spring I) to remove it from the toe 5" and permit theretaining pawl to rise into engagement with the teeth b", the stop I) at the. same time leaves the fixed stop 6"", the spring 6 swings the pawlb around the 'ivot 12 until its point engages the teeth on t e ratchet wheel b each tooth on this wheel moving the arms around over five contacts m at a jump, while each tooth 1) moves the arnis over one contact singly. As the awl b" pushes the wheel b around the toe 51 on the upper end of the armature lever comes over inthe path of and serves as a stop for the teeth on a second wheel 6 furnishing a positive stop-for each step in the rotation. Each arm hasan annular collector ring, I), as stated, upon which rests the spring bF". When it is desiredtd remove the switch body from the rack, the .arms are turned allthe way around until they rest on the fixed contacts .Further description of "they-B and C swltches is unnecess'aryjn view of the statement of'operation hereafter, and the fullness of the illustration. It is to be underb, and comeaway-with the' stoodthat we intend to claim everything we I have shown as our invention.

Referring now to Figsf'fi and we will cessity for a double point out briefly the distinctive features of the Gr switch shown herein. The only difference between this switch and the B and (l switches, in essentials, is in the number of relays they carry. Each of them has the same kind of a base-plate E as that already described. Each has a similarbridge e? and each has its own spindle and arms. This switch G- has ten contacts if ten per cent. of connective apparatus is required, and twelve if twelve per cent. There is no nem ovemcnt; there is only magnet, M and a rea single actuating;

lease magnet M w The arrangement of the switch base It and the frame carrying the bank contacts,

well as the sliding contact spring connections between the two, is the. same as in the The relays employed are, with one exception, of the form shown in Fig. 4. The exceptio'n i. shown in the relay M illustrated.

at the'bottolm of Fig.2, and in the middle of the bottom of Fig. 1. 'illhis is a polar relay, havi iv a straight 'annature s resting on a knife go on the end of its core and tilting o e way or the other according to the di n of current and consequent magnectic ,ari ty oi the iron core and armature. Straddl g the entire winding 15 a magnet S secured its neutral point 'to the inactive end or the core. this magnet "secured aflealt spring 3 having; its endbent up and resting upon. the 'aised middle portion of the armature over fe e'dge,so asto hold the armature in on. Alongftheother arm of the mag- *e sccurea contact spring- 18 forming one Sande release inagnet M of the connector switch,

in addition to being working magnets, each controls contacts in circuits,the functions of which will, be further. described. In each casethe contacts aresecured to'the frame of the magnet and are actuated by a lever, one endof which forms the armature of its respective magnet. i

[Referring now to the circuits, first of all it will be observed that we have shown at the subscriber-s station what are known as standard Strowger circuits and apparatus. This substation circuit needs no description for those skilled in thepart, but it should be understood that wecan substituteother suitable mcansfor operating it. The simplest form of apparatus we can use at the substation comprises two push-buttons each connor-ting one side of the line to ground when depressed, and an ordinary common battery talkingcircuit. To work the system herein illustrated the successive sets or groups of impulses are sent by grounding one side of one arm of of the circuit to be controlled, the armature forming the other.

the line in succession the desired number of times, and grounding the nmteside of line the calling line and connects it to a B switch with which it is associated, The B switch steps around its arms in obedience to impulses, each stop taking five contacts, and each five contacts representing live trunks to the next order of switches. When the desired groupjs reached, the single impulse over the other side shifts the energizing circuit, and the escapement magnet comes into play, stepping the arms back one contact at a time until an idle trunk of the groupis reached. It should be observed that'theroturn movement is produced by "the ordinary retracting spring.

Having extended by those successive steps the calling snbscribe-rs line through to the connector G, shown in Figs. 11, 6 and 7, the connector is permitted "to select the called line with which connection is desired, by

actuating the connector the required numberof times by impulses from the calling partys station. 1 1

The battery connections throughout the circuits are from ground to both sides of the line normally, and not until the called suhscriber answers is talking current cutback to the call ng subscriber. By this means we are enabled to regulate the operation of rogistering devices by employing the polarized relay M ,'(F1g. 8) arranged in a circuit terminating in the contacts m with which the wiper a of switch A cooperates.

The balance of the circuits will be better understood from a statement of operation, tracing one call in its progress tl'irough all the switches. as follows:

In tracing a call through from telephone A (Fig. 8) to telephone B (Fig. 12), the

first operation is that of subscriber A rcmov ing his telephone from its hook, thereby closmg contact sprlngs o and 0", which are connected to the ma n line wires by the following route: wire 3, sprlng 0, spring 0?,

wire 5, transmitter T, winding I of the in- The operation of the system is duction coil,,'wire 1 (one) to line-"12,thus

closing the line circuit. This circuit may be traced by the following path: 11, 159, relay M, 158,spring 178, spring 179, wires 152, 153, to the grounded side of battery l through batteryto wire 155, relay M wire 150, spring 176, spring 177, wire 157, through mate line 12 towirc 1, completing the circuit through the A subscribcrstclca call.

* curring relay phone, as above described. This action energizes relays M and M. In closing, the relay M operates its armature, springs 173 and 174 and closing springs 174 and 175. Spring 175 is connected to ground through wires 161 and 153, and when in contact with the spring 174 throws ground on wire 154. The object of this is to prevent any other subscriber from calling in to this subscriber,while he is in the act of making This relay M in operating also breaks the springs 170 and 171, and closes springs 17] and 172. Contact spring 171 is connected to the grounded side of battery through wires 152 and 153, thus connecting grounded battery to wire 160, contact springs 180 and 181,wirc 9. WVhile this action is 00- M is also energized, but belng so constructed that it operates more slowly than relay M itdoes not open the circuit between springs 180 and 181, which we have just described as completing a circuit from ground to wire 9 until the circuit of relay M, Fig. 9, has been closed by the following path: wire 9, contact spring a, contact m wires 24 and 15, through relay M to wire 16 to battery. When relay M operates, by reason of the momentary grounding of its circuit over the wire 9, it closes springs 183 and 184, also Springs 189 and 190. Spring 183 is connected to ground through wire 25, contact spring a and wire 195. Thus it will be seen that ground will be thrown on spring 184 and. on spring 189, through wires 21 and 25. This ground on spring 184 can be traced through wires 25 and 15, through relay LI and wire 16, thus keeping it energized. The ground on spring 190, above described, will energize magnet M through wire 18, contact springs 191 and 192, wire 17, through magnet M wire 14, battery, giving to the motor magnet the initial impulse to advance the finder switch one step, additional steps being imparted by which wiper a engages 'a grounded contact in the bank m and until said wiper engages the terminal'of a calling line from-which the ground has been removed.

M is a motor magnet of a switching mechanism similar to our other switches. This switch will hereinafter be referred to'as the finder switch. When, therefore, M is energized, it revolves shaft A through the instrumcntality of pawls anddogs, not shown in .this diagram. Shaft wipers over contact points until wiper a ceases to find a contact that is grounded. As soon as wiper 0 passes from contact a to the grounded contact segment a", and actuates the starter by throwmg ground through Wires 13 and 19, contact a, 'Wire 7, through magnet M flwire 8, contact springs 193 and 194, wire 8 to battery. magnet of another switch, which will hereinafter be called a starter switch, WhichLreopening I A carries a series of M is the motor POSIl'lOIl on contacts on rolves its shaft A similar to the other just mentioned. This mores wipers a and a over-contact banks m and m ,'respectively. These contacts are connected to other finder switches in the same manner as contacts m and m are connected to the finder switch, as illustrated particularly in Figs..8' and 8 and 9. Now, referring to Fig. 8, it has been above explained that when relayM has been energized the contact between springs 170 and 171 is broken, thus taking the ground connection from spring 170. This spring 170 is connected by Wire 151 to contacts m. These contacts are the multiple bank contacts in front of four separate finder switches. A greater or less number of finder switches may be used as described. Therefore, if any finder switch has been started, it will immediately stop on one of these contacts. In this case, the finder switch, Fig. 9, will stop with its wipers on one of the multiple contacts m appearing in the bank ofcontacts in front of this finder switch for this particular subscribers line.

NV. ha re already shown how the starter 'switchstartcd the finder switch in this instance. It will now be plain that this same starter switch can start other finder switches, shown in Fig. 8, such finder switches being connected to contacts m and 122?. Should there be sufficient calls from other subscribers to step this starter switch to the last set of contacts-it will be released as follows: the interrupter X is so arranged that it will throw ground impulses on contact m thus it can be seen that when wiper (0 reaches contact m3", grounded battery will flow through contact 722-,-wi ')er a wire 6, release magnet M wire 8, to battery, thus energizing release magnet 1W allowing the wipers on shaft A to return to their 1101111211 and m. i

We have now shown that the fin dc: switch, Fig. 9, has been caused to operate and has placed its wipers (a, a, on contacts-m m, thus connecting lines 29 and 30 respectively to lines 11 and 12 leading back. to the calling subscriber. I i

\Yhen the finder switch,- (Fig. 9) stopson the contacts above described, relay M (Fig. 8) will be energized as follows: spring grounded battery current m wire 200, thr'ough relay L1 wiye 155 to,

battery. \Vhcnthis relay is energized the contact between springs 176 158, relay h wire 159;:1150 breaking the and 177 and b'e- V tween 1-78 afid'179 is broken, thus breaking the ground connection from spring 178, wire connection to relay ,M s, through 'wire 150,

springs 176, 177, w these breaks is to freethe line wlre 11 and mate 12 from allc'onnect'ions with the appawire The object of' thus energizing ma ratusshown in Fig. 8, and also to deenergizrelays M and M.

This completes the necessary switching operation to connect the talking circuit from subscriber A to the B switch or first selector.

This also closes the busy trunk by the engagement oil? the wiper c with contact a net M over the following circuit: groun contact or, wiper a, wires l3.and 19, contacts 188 and 187, wires 1 and 34, wiper 6, wire 41, magnet M,

34 and engages a contact segment wires 40, 54, 52 and 51, battery and ground.

Now, by grounding wire 3 atthe sub scribers station the j required"number of times to select the desired trunk leading from the first selector to the second selector or to the connector switch in the event a second selector is not employed will cause magnet M to be operated. This circuit may be traced as follows: starting from subscribers station, ground, wire 3,'wire 11, a wire 29,

spring 71, contact '72, wire 73, winding of magnet M wire 51, battery, ground. M in operating closes the following local circuit: ground; main battery, wires o1, 52, magnet Ml, :Wlle 53, spring 59, sprin- 60, wire 61, spring 62, contact spring 63, wlre 65, ground. Magnet M3 by ratchet arrangement, turns shuftb, to which wipers 71 ,12 and b are at tached, causing the same to turn with shaft 6. Magnet M in turning shaft steps it over live contacts m (Fig. 10). Now by the movement of the spindle b, the rotation of which has been previously started, the wiper I) moves into engagement with contacts m. At the same time wiper I) cuts out the wire connected l8, against which it restsafter *tothe wire of its normal position, allowing inc-ring out the magnet M to be energized bycurrent n holding circuit: ground, mam

the followin a 52, 54, and 40, magnet- M,

battery, wires 51, wire, 41, wiper bi, wire at magnet M wire 44, contacts 77 and78, wire 7 9 to ground. i Therefore, M would continue to hold up even. thougl'i the spindle b was being turned by, magnet M We will now close the'circuit from ground once at subscribers station over wire 1, (one) wire 12, contacts we, wiper a, wire 30, contacts 74 and '75, wire 76,;winding on MLwire 50, battery to ground; this, operation of the magnet M would. open contact. between springs 77 and 118, depriving M- of itsssource of ground,

which would then, if the wiper if? of the i switch was at that time standing on a ground on busy contact of ml, continue to hold up M: .if then the wiper 7); does not happen m-have' a source of ground, M would there for) have to release or drop back, extending Huglincs that it had just previously opened to the first selectons'witch (Fig, 10) and cutting oil' the magnets M and M that it ture no longer.

48, contacts 47 and exists until the relay had just previously connected. If, however, the wiper I) was on a grounded contact, then winding of M would hold up over this ground as well as M. We would alsothen have a circuit through M starting at m, supposing it was grounded, 6 wire 43, winding of M wire 44, spring 77, contact spring 80, wire 81, wire 82, Winding of M, wire 50, battery,.ground. We thenghave a circuit through magnet M in parallel with the circuit of M, from wire contact spring 85, wire 86, winding of M" wire 87, wire 50, main battery, ground, Magnet nectexl with shaft 6 and. when ener ed makes and. breaks its own circuit 1i e a buzzer. Shaft 6 being under tension of a retractile spring drops back one contact with each step. S0 in. this manner we travel backward over contacts m so long as b can find ground- So as soon 'as W er b loses ground we then notice that M, lose their circuit, consequently releasing, and in consequence M also is diwonnectc d from battery and will, therefore, vibrate its armal.herefore, all the relays of B switch are'normal. A circuit may now be traced from contact m back through 12, wire 43, M wire 44, spring 77, spring 78, wire 79, ground. Since wiper b, on m is grounded and current flows over a circuit from contact m wire 49, (Fig. 10) wire 88, 0 wire 89, M, wire 90, main battery,

- ground, relay M is thereby caused to oper-.

ate, causing it to open its normally closed contacts and close its normally open contacts, opening wire 91 from 94, and wire 92 from wire 93, and cutting wire 91 onto relay M and wire92 onto relay M f. Now, therefore, when Wire 3 (Fig. 8) at sub.- scribers station is grounded one or more times to select the trunk leading to the second selector switch,,it will be seen that re lay M operated, which. acts to. energize M. with each impulse of current causing it to turn the spindle .lo a suflicient distance to move its wipers througha space of five contacts.

When the shaft 0 takes its first step, the

brush 0 passes from the terminal of wire 88 on to the terminal of wire 480, thus inter-- winding M is similar in action to'M' and is capable under proper condition ofbeing actuated by successive impulses of current from the calling subscribers station Whenever the line 3.1s grounded, which condition W-i g ounding wire 1'(one)' at subscribers 81, spring 84:,

a substitute circontacts of relay M is deenergized. 9

station once causes M to be operated b current in the following circuit:

the windingof M in parallel, contacts m,

, Fig.- 10) ground m.

m ,,.wire HQ-winding of relay MP wire 430 and wiper 0 to terminal contact m As the original energizing winding for M passes through normally open contacts of relay M it will be seen that the continued energization of M, M and M is dependent upon the contact m on which brush c rests, being grounded. If the trunk represented by this conta t is idle, no ground will he on contact an and the above relays will become deenergized and no further movement of the switch shaft 0 will take place. If, however. a multiple of the contact m is engaged by another. selector, m will be connected to the wiper c'- winding of ground through said multiple, of the switch thereon, wire 130, M and contacts Wt ,.7)t to ground, thus relays M and M will be liiaintaine'd energized and the magnet M, which interrupts its'own circult by every energization at contacts m, will be intermittently energized to permit the shaft 0 to rotate backward step by step until wiper 0 fails to find ground on the terminal contact m of an idle. trunk, when the circuit for relays M, M and the. magnet M will be interrupted. as before described. The dei nergization of relay M by closing conm m places ground on the contact m; thus making the trunk busy. Thiscil cuit may be traced over the following path: contact m, wire 440.

i'nagnet iii, wire 430, wiper 0", contact on. (Fig. 11) wire 95, wiper 7 wire 96, M, wire 07, battery to ground.

We, therefore, see that M'. will be energreed. opening its normally closed contacts and'closing its normally open contacts. causing wire 08 to be separated from wire 5)!) by contacts [00 and causing wire 100 to be sepa araled from wire 10] by contacts .100. We also seethatconnected to wire 08 we have, magnet M wire 102, spring 103, spring 104, wire 105 to main battery and ground; On wire 100 we ha \e tapped niagnct- M, wirelllli, spring 107. contact. spring 108, wire 100, spring 1 l0. contact spring 1 l 1,, wire 112, wire lllfi'to main battery ow suppose that. we'groiii'iil wire '3 at s 'l lisc 'r 'l'i "s stationthe necessary imunbcr of o operatethe selected connector switch to iiiiu se its wipers .divid-ual line),

to take up the terminals of the called partys line. Each time wire 3 is grounded, a. 011'- cuit is completed from ground at substation .over the upper talking strand of the line now complete through to wire 98, Fig. 11, 70 winding of magnet M contacts 103 and 104. to battery and ground. Each energizetion of M completes a circuit'from battery, through wire 98, contacts of M "now energized, the winding of M, contacts of M and contacts of M to battery, tlius energiz ing M. Magnet M moves the shaft and its wipers forward one step or one set of contact terminals each time it is energized. was originally It was just described how M energized through wiper g. This original circuit through is broken with.the first step of the shaft 9 butanother circuit for relay M is now established, from battery, over wire 97. winding of M contacts of 11" and contacts of M back to battery. 'l'here't'ore as long as M remains normal, M will be held up and the shaft. can be stepped around as far as desired. Now grounding the lower talking strand of the line at substation A completes a circuit over. the lower talking-strain'l of the line, through relay contacts 107, 108. contacts 110 and ill to battery and ground. This will operate M'-'j-, interrupting the circuit just traced for the relay M. if (he called line is idle, M will become dta nergized, extending the talking strands 9b and through to the brushes of the switch 9. All of the relays will now he in their normal condition.' Now. 100 We will suppose that the cont-act m on' which lh'e. shaftplaced the wiper g was busy. (heinggrounded tooperate M to clear the line during the lime connection is estab lished therewith) we would then ha ve ground on this contactso, therefore, considering ground on the contact m wiper 5], wire .l-Zl. wire 117. spring 116, contact spring] 15. wire. ll-l. wire 113. 1V .wire 97. battery t ground. 'lhcrct'orc. if this line is busy, magnet M will remain held up and will not relcase even though Mf-iis operated. which will prevent any one {from coming in on a line that is has Now. again, supposing that the line was not busy and the connector switch did cut through. we will notice that'when M'" and M drop back. we have ground (.l ig. 11) by wire 120. spring 115 contact spring 118, wire 117. wire 121 to' g oi rtoa contact m" (Fig 12.) wires 122,123,.M, wire. 124 to main battery and ground, which causes M to operate. Wires 125 and 126', (supposed to bB'tll(5 (',tlll((l subscribers inare thus cleared from an connection with A". representing the multi 125 ple-eouta-cts of said line in front of the tinder switches. Now,*we therefore havegonethrough .and'connected with the de-' sired line (it. is understood that wires 1'25. and 126 extendto subscriberstation). .W'e 130 circuit o'l M. and M? is as follows: ground.

now know with M in its normal condition and shaft 9 oil normal, that 51 engages the interrupter which makes and breaks the ground, and thereby -M is caused to be drawn and. held for an instant then released, then again drawn up and released, etc, as long as the conditions just described are true, over the following circuit: ground, interrupter 300 wiper y, relay magnet M springs 301., 302, 302- and 30%, wire 30;), to main battery. 'l hus M operated in this manner, as shown. by the contacts, throws a ringing current out to the called subscriber, ringing his telephone il'itermittently until he answers or until. the calling party hangs up. N on, supposing that the called party answers. it will'hc noticed that M is tapped on to one side of the line, the other side of the winding going through wire 10?) to main hatter It will also beuiticed that h is tapped on to the other side of the line and the other side to groind. So, therefore, thecalled party in taking his receiver oil the hook causes NP" and M to act. closing their normally open contacts and opening their normal l v closed contacts. It will he noticed that M and M have their circuits open when M? acts. It will also he noticed that M" and .\l'-'" have their circuits normally open. hut are closed as soon as M acts. The

wire 1120; niagrncl M. closed contact springs on magnet M to the side of the line represented in JH back through the. several switches to suhscrihens station, thence by the othcr'sidc oi the line to wire lOO, contacts on relay M, to relay N1 and mai lialh-ry. 'lhcrelore. the called party in tali-i mg his-receiver oll' has done two things: cutting oll' M and M and cutting on M and'bP". and in this way has given, the call.- in; par! v what we might term talking cur rent." Now after the conversation is fillishcd. ii the called party hangs up first he i'nllscs holh sides or his line to be grounded.

. and then the line side, 1525, to be opened.

while the mate side, 126, is still grminded. To accomplish i'lns thc suhscrihers sub-stalion is so construcltal lhat'itwill hold ground an instant longer on the hattery side of the lino than it does on the gl'UlHH'lBd side of the line and which operates the release over the following circuit: ground, main batterywires PM; and 316. s n-inns 317 and 31.8, wire Wires 323, 314 and /a' and wil and ground. By this operation. it will he soon that M drops hack and that M holds up, ('losinglhe release circuitiot M ovi-r the following path: (Fig. 11) hat tery. contact springs on WP (nowweloscd). contact sprinyzson NP (now closed) magnet M. hank contact wfifflig. 10) wiper .0 wire $30, magnet 1V wire MO, springs n i), ground.

M and the latter operating causes its local magnet M to act by an in'ipu'lse ofcurrent traversing the following path: (Fig. 10) battery. magnet M, contacts on M, wire l9, hankcontact m (Fig. 9) Wiper b Wire +3, relay M", wire i l, springs 77, 78', wire This circuit causes M to act and close its local contact and energizethe circuit of M and'M, traced as follows: ground, wire 79, springs 38, 37, wire 33, magnet M wire 14- ,to battery also from wire 33', to wire n'iagnet M, Wire .34, 52, 51 to bat tery. Therefore, when M loses its ground the entire set of switches is released to return to normal. it thefealling party hangs up before the called party, then the calling party momentarily grounds both sides of the line, then ln'eaks the line side, 98, which includes M. and the mate holding up M over the following circuit: gronl'id main battery B. wires 306 and 307, springs 308 and toll. wire SH). springs 311. a d .312, wires sides of the line would he closed inomentarily when the calling party hangs up, causing ME" and hl to pull up at the saline time which closes-the release over the follow- I inn circuit: grouiid. main battery, wires 306 and 524-, sprinn's i-llfi, 326 and 327, wire 317:. ina nut .\l'-. wire 95. contact M wi ier r5 win no. magnet on, wire 440, springs pm' and 1/8"" to ground and thereby releases the switches.

Having. thusdescribed our invention, we claim: 1

1. 11:1 an autoniatie telephone system, the ronihimition with a plurality of normally open instrunuut wircuiis having terminal contacts arranged in ii switch hank, norl'nally I closed operating circuit branches and normally open stariing circuit l 'anchcs corresponding to each instrument circuit; terminals for thc operating; circuit branches arranged in 1-1 switch hank and Wiperscoiiperati'inr'with said hanks. of a line relay bridged ,to each inslrlnncnl circuit and adapted to opcn its corresponding hranrh operating cir cud. wipers cooperating with the d llcrent hanks of contacts and elcclroinagncl'u' opersiting nnchanisin l'or automatically advancjinn said wipers progressively which adaplcd to he :n-iualcd hy the closing ol a hranch starting circuit and lo continue the movement ol'lhc wipers during the sucrrs' sire cngagrnu nt of one o'l' them with the ter- 'n|inals ol" closed operating circuit hranrhcs.

:li'lll-oll relay also associated with each inslrinncnl circuit adapted to openitsline relay while. the latter continue to engage the ter-.

branch operating-circuits corresponding to each instrument circuit also having multiple terminals arranged in banks on the various switches and separate wipers on each switch cooperating therewith, of normallyinoperative electromagnetic operating devices for each switch mechanism fol-automatically advancing its respective wipers" as one of them successively engages the terminals of closed operating circuit branches, a starting mechanism for rendering said devices capable of operation, a. local starting circuit for sup 'ilying an initial impulse of current to starta switch mechanism which is connected to said mechanism by the sta; Ping operating devices. normally open branches of said local circuit corresponding to each instrument circuit, meansfor closing them and opening the corresponding operating circuit branch and devices actuated upon the movement of each switch in turn to operate the starting mechanism to connect the local starting circuit to anotherswitch. v

3. In an automatic.telephone system, the

combination with a plurality of switching mechanisms comprising banks of terminals and wipers cooperating therewith, a plurality of instrument circuits connected in multiple to terminals in the several banks, of normally ino -ierati ve electro-magnetie operating devices for each switch adapted to be rendered active to advance. their wipers ininals of open instrument circuits, a local starting circuit having normally open branches corn-spolnling to each instrlnncnt circuit, two relays having dill'erlrn-t time constants bridged to each instrumcntpircuit and vcontrolling its (;Ul'l(S[')(Jll(llll, branch operatlngcn'cuit, the relay responding to current impulses with less rapidity being," ,adapted to open said branch after the t|llll est relay [has closed it, a switch-starter ianism arranged in the local portion. o ing circuit comprlslng ternnnag i-icctromagnetlc operating llOVlt't'S ol cl 0 starti ljor the the sevl i v1 cral switches and a wiper cooperatlltgdthurelin-lzh anlsnr starter cn .with, thel'nnction ol' the starter be ng to successively conncctthc cuit with onc or another of theslwitdh operating mechanisms. and devices l'iir actuat iiigthc starter mechanism.

having a circuit adapted to be closed to acless in number 4. In an automatic telephone s Stem, the

combination with a plurality o switches comprising banks of terminals and wipers cooperating with them, electromagnetic mechanism for advancing said wipers embodying a motor magnet having a normally open circuit, a controlling relay associated therewith for closing said circuit and a local starting and a local operating circuit over which current may be supplied to the relay at difi'erent times, of a starter switch mechanism comprising terminals for the control ling relay of'each switch and having a wiper cooperating with said terminals, a plurality of instrument circuits connectedin multiple to terminals in the various switch banks, branch starting circuits corresponding to each instruih'ciit circuits connected in multiple to terminals in the various switch banks, branch starting circuits corresponding to each instrument circuit termiliating in the wiper of the starter-switch, o ')erating circuit branches also corresponding to each instrument circuit and having multiple terminals arranged in banks on the various switches, wipers on each switch arranged in the'local operating circuit of its controlling relay, means associated with each instru mentcircuit for closing its corresponding starting circuit branch and opening its operating circuit branch, and means fonadvancing the starter-switch after one switch has been operated to render another switch in condition to be operated.

5; In an automatic telephone exchange system, a plurality of subscribers lines, a line relay for each line, a plurality of finder and selector switches, a relay for each-tinder switch, a starting circuit for the tinder jointly controlled by the said relays to produce a momentary current in the starting gircuit, and means to restore the switches on the completion of a communication, substantially as described.

'3. Tu an automatic telephone system, a plura lity of subscribers lines, finder switches than the number of lines, and means for operating said finder switches to find the line when said line is closed, selector switches connected to said finder switches, and two magnets for said selector switches adapted to be operated over opposite sides of the connected line, one of said magnets being arranged to produce a long step'over a series 01' contacts in said switch and the other magnet being arranged to produce a series otshort steps to terminals of the lines passed over by the long steps.

A telephone exchange system comprising aplnrality of telephone lines, a pluralto its final selecting movement to free said master switch for further use, and means for actuating said master switch once and once only per call.

8. telephone exchange system includin telephone lines, a plurality oi selectors eac I having access to sa1d lines, a master switch for starting idle selectors to establish connection with calling lines, a starting circuit normally extending from said master switch to an idle selector, and means actuated by a started selector prior to the final selecting movement to free said master switch for further use.

9. A telephone exchange system includin telephone lines, a plurality of selectors each having access to said lines, a master switch for starting idle selectors to establish connection with calling lines, a starting circuit normally extending from said master switch to an idle selector, and means for adjusting said master switch and connections altered by a started selector prior to'its final selection to free said master switch for further use, said means then serving to adjust said master switch to establish a starting circuit extending to another idle selector.

l0. 'ln-a switching mechanism, the combination with a plurality of terminals, a branch circuit leading from each terminal, a, contact element cooperating with the terminals. and a spring operated device for advancing the element, of a motor magnet for setting the device in actuated position against the tension of the spring, a circuit controlling the operation of the motor magnot which is completed over one or another o't the circuit branches upon each advancement of the contact element to effect the energ'izing of the motormagnet and means for I subsequently breaking said circuit to eflect the deener'gizing of the motor ms. t and a source of current supply for said circuits.

11. The combination with a plurdlityof lines, of a plurality of finder switches for makin connection therewith, a starting circuit a apted to be closed by any of said lines in calling and adapted to start one of said switches, means made operative at the outset of the movement of said switch for advancing said starting circuit to the next switch, and means for preventing said calling line from starting said next switch.

12. The combination with a plurality of lines, of a plurality of finder switches for makin connection therewith, a starting circuit with which one of said switches is in operative relation, means actuated by any line in calling for closing said starting circuit to start said switch, means actuated by said switch at the beginning of its movement for bringing another finder switch into operative relation with said starting circuit and means for depriving said callin line of control of said starting circuit be ore said second switch comes into operative relation with said starting circuit.

In testimony whereof I ailix my signature in presence of two witnesses. V JACOB WILLIAM LATTIG.

\Vitncsses:

I'lURAllO Srnaos, Josnru ll. VEBSTER.

In testimony whereof I afiix my signature in presence of two witnesses.

CHAR-LES LANE GOODRUM.

\Vitncsses:

M. H. SKALOWSKI, Hownrn Conn ERWIN.

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