US976524A - Automatic telephone system. - Google Patents

Description

H. G. WEBSTER.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED HA2. 6, 1909. 976,524.

Patented Nov. 22', 1910.

6 SHEETSSHEET 2.

' H; G. WEBSTER. I AUTOMA'IIG TELEPHONE SYSTEM.

. V 1PPLIOATIOIPILED IAILBJ 1'1909. 976,524. Patented Nov.22, 1910.

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11; Va. WEBSTER: I AUTOMATIC TELEPHONE SYSTEM.

I APPLICATION FILED HA3. 6, 1909. 976,524. Patented Nov. 22, 1910.

H. G. WEBSTER; I AUTOMATIC TELEPHONE SYSTEM.

. I APIPLIOATIQIf Hum uni-e, 190a. Patented 22 19170. I r s sums-51mm 5; f0

1' v I 70 I Mb I i r04 WWW v mmv mg V im H. G. WEBSTER. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION FILED M13. 6, 1909.

Patented Nov.22, 1910.

UNITED STATES PATErTT OFFICE.

HABBY G. WEBSTER, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO KELLOGG SWITCHIBOARD dz SUPPLY COMPANY, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

To all wlidrrimy concern:

Be it--known that I, HARRY G. -\rVnns'rau,

residing iii-Chicago, Cook county, State of Illinois, have invented new and useful Improvements in Automatic Telephone Sys-' tems, of which the followingis Lspecificw. tion.

While the invention, as defined in the claims, may be employed for automatic or semi-automatic systems, I have elected to illustrate the same as embodied in the system of the former class, wherein first selectors, second selectors and connectors are employed for operation responsive to directive currents controlled at the calling substations, to interconnect subscribers lines. Iireferably, the first selectors second selectors and connectors are provided in numbers proportionate to the numbers of co-existing calls to be expected, and'auto- .matic means are provided to interconnect the first selectors interchangeably with calling lines when calls are initiated from such lines.

The first selectors in the system illustrated are employed to select the thousands digits of the called numbers and consist of step-by-step switches having before them a number of groups of multiple contact sets which are terminals of second selectors as-- signed for connections to the different thousands of the exchange, an operatingfirst selector being directively adjusted to selectthe required group of second selectors, then automatically to selectan idle'-se1'ector from the group. Each second selector isan auto. matic switch having before it groups of multiple terminal sets of connectors, those of each group being assigned for connections to a different hundred of the thousand which the second selector serves. A thousand first selectors, a thousand second selec-' tors, and a thousand connectors. may conveniently be assumed suflicient .for 'adef qua-tely caring for its business ina ten thousand line exchange, The arrangement ofthe multipling of the terminals of the connectors at the second selectors and of the terminals of the second selectors fat the first selectors, may be of a customary 'well known character; and need not, be more specifically referred to. In the usual way, the linemas called lines are divided into groups ofi-pne hundred. according to the d1reetory'mim-' bers of the lines; and each group of one hun- 1909. Serial m. 481,792.

r dred lines has multiple called terminals ar- \pulses, representing the tens digit otthe .cal e number, to select the group of multiple terminals containing that of the called line; and to be thereafter adjusted responsive to directive im ulses representing the units digit of the ca led line to select out of the group the individual contact set of the called line, whereafter the line will be tested and, if ,idle, its substation will be rung up,while if busy, a signal indicating that condition will be transmitted to the calling subscriber.

As calling line's, the lines are also divided into groups of one hundred and the multiple calling terminals of each such one hundred line group are multipled before the wipers of a number of line selectors which are automatic switches capable of selecting the terminals of a calling line. The terminals of the lines of each one hundred line group ma fbe multipled at, say; ten line selectors an each such line selector may have paired with it one of the first selectors. Thus assuming a ten thousand line exchan there would be one hundred groups 0 calling lines with ten line selectors per group, making a total of one thousand line selectors, each line selector havingpaired with it one referred'to. A

The present invention is directed to an improved mnstruction and method of operiation of the'line selectors, and to improved apparatus for controlling the mechanical switches employed for first selectors, second selectors and connectors. The mechanical I do not cla m as partof the invention.

I am aware that the use of automatic switches for selecting callin lines and so connecting central ofiice linicircuits with th m is not new. One class of s stems of this charactenheretofore ro ose has contemplated placing the mu tip e terminals of the calling lines at the line selectors in a single group. In such cases, the wipers of the line selectors when selecting a calling line, may ossibly have to pass over the entire num r of contact sets provided in of the one thousand first selectors previously switches employed in these latter capacities.

, step, each step being the same len th.

order to reach the set of the callin line. As the calling line groups are preferably of quite large size, the selectors in such systems must in many cases take a rather longer time than is desirable to selects calling line, or must be operated at a speed so greatas to tend to impart unreliability in the operation. In another class of systems wherein line selectors are em loyed, the terminals of the lines are inultip ed in groups at the line selectors and these switches are first adjusted to select the group and then termlnals of the calling lines much as theconnectors are operated to selccta group and then the terminals of the called lines.

In the first class of systems, obviously a simple'rotary switch having one direction .of travel may be employed and such switches are preferably arranged to operate stepFby or systems of the second class, it,has been proposed to use switches of well known character having .wipers capable of adjustment in two intersecting planes, or switches having one set of wipers to select the group and other sets to select contacts of the group, or

. rotary switches arranged to make long steps cured by-the s stems o the said second class.

Brie in t e particular system shown, I secure t e advantage aimed at -'by arran ing the multiple contacts of a. one hundred ine group of calling lines in sub-grou s before the wipers of the line selectors an provide as many sets of wipers as there are sub-'f groups of terminals. All such sets of wipers are'normallyin inoperative condition. For each set of wipers, a relay is provided which is common to that sub-group of lines with whose terminals its associated wi rs are adapted to make contact. When a ine of a articular sub-group initiates a call, the 'reay assigned to that sub-group of lines will energize and operatively connectthe roper wiper contacts of the line selector with the other mechanism so as to render them live or effective to select a line from their subroup, while the wipers of the line selector or the other sub-groups remain dead or disabled Thus assuming that the one hundred lines of a calling group are divided into five subgroups of twenty lines each and the multiple terminals of ,the lines of each sub-group occupy approximately one-fifth of the cireach line solector' there will then*be five sets of wipers preierably rotatably mounted essary for the wipers to'be rotated through an arc of seventy-two degrees so that they respectively occupy adjacent between-group positions. By rendering one set of wi er s live by the operation of its associate relay, and rotating a shaft to which all the wipers are attached,'the set of wipers ren dered live will at some point in their rotation engage the multiple contacts of the calling line and the mechanism will be stopped, the calling line being thus selected. When the selector is to be restored to normal, rotation is again set up in the original direction and when the wipers reach the next between-group position, the mechanism will be automatically stopped. -To enable the use of a switch of this character, the terminals of the circuits of the line selector are common strips and the multiple terminals of the line are placed adjacent to them, the wipers of the selector beingipsulated one from the other and crossing a common to successive contact terminals as the switcl'r 's operated. 9 Referring to the drawing, BMcgmprising parts 1, 2, 3 and 4, illustrates iagr'ammaticall circuits embodyingo'nea1? plication of t e inventiom Figs. 2 and-3 are,

respectively, plan and side views of a line selector, the latter view being partly in section; Figs. 4 and 5 are like views of a long and short step selector; andFig. 6 shows in section a detail of the connection between the driving pawl of the selector and its actuating part. At C 1n Fi 1,-I show a subscribers station connec by its telephone line with a suitable line circuit arrangenie'ntat the exchange. At D is shown a master-switch circuit; at E a line selector circuit; ati'F a controlling circuit for'efiecting the switchipjg operation of the first selector shownat t e second selector shown at I, and the connector shown at K- C indicates a. second 116 subscribers station similar to that illustrated at G and assumed for pl'zrposes of description to be the called substation.-

A callin line group will comprise one hundred te e honelines with arran ements 120 pertaining to five different groups of lines.

The reference characters a, b, 6, cl and e are employed alone and in conjunction with reference numbers for the a paratuses individual to the first, second, t ird, fourthand 65 cumf-erc-nce of a circular contact bank at fifth groups, respectively. The line-o'f-substation C is assumed to be in the sub-group of lines a. Each of the twenty lines of such sub-group will have its individual line relay -"t'iiry switch construction including a stepbyste J magnet M adapted to drive the'four sets 0! wipers 43, 44, -15, 46, having their opposite ends insulated from each other, ro-

" tarily over their respectively associated common strips and stationary contact points. The master-switch controls mechanism for starting an idle line selector under the influence of a group relay 17 when such a relay is o )erated'by the line relay of a calling line. Each line selector E is provided with five starting contacts at the master-switch D, namely, a contact 32, a contactc34, a, contact 36, a contact 38, and a contact 40 for the a,

b, 0, cl and 6 groups, respectively. Connected with the respective contacts mentioned, each line selector E has a'starting relay, one for each sub-group, those for line selector E at Fig. 1 being indicated by reference characters R, R, R, R and R The wires (1, b, c, rl, a, controlled by the armatures 18 of the different relays 17, lead to the segments 31, 33, 35, 37, 39, respectively, with which the contacts 32, 34, etc.,-already described,

' are adapted to be crossed by the wipers 43,

44, etc, when the latter are rotated. The normal position of the wipers is' one wherein they engage contact sets 32, 34:, etc, connected to an idle line selector E. Thus when a line of any of the five sub-groups initiates a call, the grou relay 17 of that line group will he operate in; the calling line is of the a group, will close a circuit over thewire (L, over somewho a. connected to an idle line selector, and through the relay R of that. line selector, whose armatures will thereupon efiect connections to render the wiperset for the a line group live to select any unselected calling line out-of that group. The relay R also initiates the selective travel of its line selector which automatically continues till it connects with a calling line. If on the other hand, a line. of some other sub-group, sa. sub-group (I, initiates a call, the group re ay 17 of that line group will be operated and will complete a circuit by its armature 18 over the wires (1, d, which will operate the R relay of the idle line selector and that line selector will start in search of a. line of the d sub-group, the appropriate wiperset for that sub-group having been rendered live. After one of the relays R at E has and its armature 18, assumbeen energized and travel of the line selector has been initiated in search of a callin line in a particular sub-group, no other re ay R of that line selector can be 0 erated. If another call is initiated before t ie first calling line has been selected, the second line must wait until the selection of a first has been eilected, whereafter the master-switch D will start its travel, and when it has selected contacts of an idle lineselector E, the

P011) relay 17 of the other sub-group will lice active to operate the relay R of t capvropriatc roup at the idle line selector selected by t e master-switch D.

The line selector E may. comprise mechanically four sets of wiper contacts indicated at 57, 59, Gland on. Each set of wipers preferably com )rises five contact members insulated one rom the other and extending at angles of seventy-two degrees. All the wiper members may be mounted on a single rotary shaft, which shaft may carry a ratchet adapted to be driven step by step by the motor magnet MM. No return move ment to a normal point of this switch is required, the restoration being efi'ected by-further driving of the switch arts in the initial direction of travel. ach of .the one hundred lines of the line group is. provided with a multiple contact set at eaeh'of its ten associated line selectors. Each such set will include a primaryline contact, a secondary line contact, and a private or local line con;

tact. At 7 0*, are indicated the multiple primary line contacts of the a sub-group. Although but three such contact sets are shown, it will be understood that the 'primary segment 58,.associated with the contacts will have, adapted to be crossed to it by the wi ers 57, twenty suchprimary line contacts (0, one for each line of the a sub-group. 70", 70,- 70 and 70* indicate the multiple primary line contacts of the subgroups I), c, d, e, three in each case represent ing twenty, as in the case of the contacts 70. 71, 71", 71, 71 and 71 indicate secondary line contacts of the a to 1) groups respectively, three representing twenty as before. 72, 72", 72, 72 and 72 represent the local or private multipleyontactp of the a, b, c, etc. sub-groups respectively: It will be seen that for eaci group of primary line contacts, a contactsegment 58, 58", 58, 58 or 58 is provided which form the terminals of the conductor of the line selector, the wipers being merely devices to cross the segments to their respective contacts as the wipers are rotated: provided for the secondary line contacts 71 and the local contacts 72. It will be observed that the off-normal on; wipers serve, when the switch is operated, to merelyLclose A corresponding arrangement is three make off -normal contacts which lad . flow over the line, denergizes instantly,

.ling the adjustments of the directively operthisIt controlof tneli'eigte selectodrs E to select ----ca'i i be un erstood from the followi n g lmtive of operation.

the wire 54 individual to line selector E (the to a normal oint, and to break an off-normal contact 374 which will be again -closed when-normal is reached. Associated with the primary wiper set 57, each subgroup of lines'has multipledy to each line selector a primary break off-nonffal contact PO to PO, the connection of two of these alone" being shown in full. Further, eachsuh=group of lines has niultipled to each line selectora local off-normal break contact EU-to LO, respectiyely, the two whose refmm characters are mentioned alone being indicated with their connections.

The circuit connection at F for controlated switches includes-a pair of conductors to which are bridged the primary relay PR and the secondary relay SR, respectively, having the serially connected "batteries A and B connected between them, said batteries being grounded at their intermediate oint. A release relay RR is provided, ointly controlled by the relays PR and SR, a reversing relay RV, and a/rclease control relal': 94 for cooperating in the restoration of t e mechanism.

The remainin connections concerned in Assuming that the calling subscriber C wishes to start a call, the removal of his receiver, by allowing the hookdever 1 to rise,- establishes a conductive bridge between the two limbs of his telephone line which results in the passing of current through line relay LR individual to the line C tige oonnection from the-op osite sides 6f" attery through the relay and to the line limbs being traced through normal contacts 10 and 11. B a1? mature 7, the relay LR locks itself an operatively short-circuits line limbs p, a, whereby magnet 3, energized by the initial current calling device 4 bein then locked until magnet 3 re-operates, w en the line selector-selects the callin line. y armature-8, relay LR ungroun s local wire L and closes ground to its branch of the common wire 16, whereby the relay 17' is ener It being; assumed that master-switch is in'the position shown, engaging the contactsof the line selector whose circuit is-illustrated at E, the attraction of armature 18 completes. a circuit as follows:-from ground at F (Fig. 1, part 2), throu 11 normal contact 90, over contacts 42 bein individual to the respective line selectors), t rough wiper 46 to segment- 41, thence through contact 18, over wire a, contactv 23,.segment 31., wiper 43, contact 32 of line selector E, wire (1., relay R to battery, energizing said relay, whose armature contacts imme iatelyassume their alternate positions. On the closure of contact 3, a cirment 62* of thefa subgroup of lines. will be observed that the individual local ground through contact 97 of relay P offnormal contact 7 3, 74 and the winding of release relay RR to the live pole of battery B. On the ener ization of relay RR, the busy or test relay TR has an initial energizing circuit closed as follows: from battery, through said .relay BR, alternate contact 91,

the busy oil-normal contact BO,'thence up through wire L, contact 1 of relay R, the

local oflF-normal contact LO, wire 56, and throu h closed contact 20 to ground. The relay 13R attracts its armatures, whereof 8O closes an alternatin current circuit for motor magnet MM, w ich immediately begins;

stepping the wipers 57, 59, 61 and on step by'step in a clockwise direction. By arma ture 81, the relay BR has connected its winding, through contact 1, with the se contact, sets 72' of non-calling lines are grounded over the respective wires L, via normal contacts 8 at the line relays. Until the segment 62 is, with the travel of a wiper 61, connected to the individual local contact 72 of a calling line whose line relay LR will then have ungrounded the contacts 72f,-the relay BR willcontinue energized by current; flowi through the segment 62, a wiper 61 and via successive engaged contacts 790i non-callin' lines of thea subgroup to. ground, where y the arinat -ures of rela BR will continue attracted and successive a ternations will flow through magnet MM,

causing its armature to" besuccessively "1;

brated, so driving the wipers of the line st!- lector E. It will be observed that the first step of the wipers will open the busy offnormal contact BO. so that the relay BR thereafter depends forcurrent upon the en-' countered local contacts 72*. Inthe present case, tlie contact set of the calling line C is indicated as being the first set in the a subgroup so that, afterthe completion of one step, the segment 62 will be crossed to an ungrounded local contact 7 2, whereupon the relay .BR will denergize and circuit connections result as follows: The relay PR, which, 1

during the energization of relay BR, was maintained energized in series with there lay SR by circuit traced through alternate contacts 82 and 84, has its circuit extended on the retraction of armature 85 as follows: over wire P, through contact 3, segment 58, contact 70 of the line of C, over wire P, contact 9, cut-oil relay CO to ground,

whereby the relay CO energizes and, by arsis RR remains operated. The energization of relay CO further deenergizes line relay LR by opening its circuit at contacts 10 and 11.

By the closure of alternate contact 12-, the relay CO is maintained energized and its initial operating circuit is opened at contact 9, circuit being traced from ground through relay CO,'alternate contact 12, local wire L, contact 72*, wiper (i1, segment 62, contact 1, normal contact 81, and to battery A.

By virtue of the circuits, then traced, it will be seen that the relays PR and SR are now connected over a clean circuit with the limbs of the substation C, and the operative conditions of said relays can be controlled by the subscriber operating the calling device 4 in a manner presently to be described. Beforeproceeding with this, however, the manner in which the master-switch D is caused to step along to select the contact set of an idleline selector E will be described. As soon as rela CO energized on the selection of the calling line, the operatin relay 27 of master-switch D was energized by current flowing from the active side of the associated battery A, through the wiper 45, segment 45', the contact 51 '(each lin'e selector E having acontact- 51' associated with segment 45-), over wire 51, the ofi'- normal contact 7473', closed on the first step of line selector E, Wire 88, alternate contact 93, to the leftthrough normal contact 81, contact 1', segment 62, contact -72, over wire L, and alternate contact 12 to ground throu h relay G0. On the energizario'n of re ay 27, master-switch magnet M has its generator circuit closed and drives the wipers of switch I) step by step. Merely to allow a better spacing of contacts 32, 34, 3(', etc., the contacts 51' are interspaeed with )ermanently grounded contact oints.- The rst'stepof the wipers-of 'ch D will therefore continue the circuit closed through the upper winding of relay 27, since so mcnt- 45 will be crossed to a ground contact, and a-seoongl actuation of ma 'net M and a second step of the wipers will be produced, whereupon the respective wipers will cross their respective segments to the contacts of the next line selector E which will have circuits identical with that shown at Fig. 1. If this is an already busy line selector, its contact 51' will be grounded These shiftings of the;

' over its res ective wire 51, through the cutoff relay C of the line with which said line selector is in en agement and circuit will be continued close through the upper winding of relay 27, and a further stepping of master-switch D will ensue. WVhen the segment 45 is crossed to a contact '51 pertain-v ing to an idle line selector E,- such contact will be ungrounded because the wire 51 will be open at segment 74; the relay 27 will be dee'nergized and its armatnres retracted, armature 28 preventing further actuations of magnet M. As long as relay 27 is operated, relay 22 is also operated and its armatures thus hold wires 0., b, c, d on open circuit while the master-switch is rotating. Armature 30 of relay 27 similarly holds wire 6 open during the time mentioned. As soon as another idle line selector E has been selectcd as described, any other line having its circuit closed by theremoval of its receiver will operate the group relay 17 of its sub-group and cause an impulse to flow over the appropriate starting wire and to the circuit of the line selector waiting to be started.

From the time thatrelay RR energized, the operated relay R is energized over a locking circuit extending through its armature 4, to ground through contact 89-90, said relay R remaining energized until the time of disconnection. It will be seen that instantly upon the operation of a relay 17 and the corresponding relay R at- E, the

ground is taken from the wire 54: by the opening of normal'contaet at 90, tfhe energizations of relays PR and RR following instantlycupon that of the operated rela B. its normal contact at 90 remains open fiom this time iuitil the time of disconnection,

' the energization of the relay R of any other sub-group of lines is efiectively prevented so that two wiper segments at the .same line selector cannot simultaneously be rendered live by the callingoflines in dilferent sub-grou s. It will also be seen that the relays 1, except the last relay 17, have their connections to the operating battery B led through se ies, contacts controlled-by one another, so hat but one of said relays can be maintained'cnergized at. one time. 'Ilhus if, during the time a started selector is operatin or the time the masterswitch D .is trave ing to pick out contacts of an idle line selector, subscribers froin two dif- The line selecting scheme above outlined may be used to connect any sort of central usual call-bell and talking circuit connections, the arrangement illustrated beingof a well-known type and requiring no specific description. The im edance coil 3 m the present case is provi ed with an armature.

controlling a pawl normally locking the dial 40f the calling device, said pawl being ada ted, on energization of coil 3, to be wit drawn from the dial to so render the device rotatable by hand. At the time line relay LR first operated, a momentary current im ulse flowed through the coil 3, and the dia was moment'aril unlocked. As soon as relayLR complete its energization, however, batte 'was taken from the line limbs of substation C by the shunt at armature 7 and remained absent therefrom until the completed operation of line selector E when the relays PR and SR were bridged across the line as before described. Atthis time, the magnet 3 became energized, and the calling device 4 was unlocked to remain so until t 1e time of disconnection.

The dial 4 is for rotation by hand in a clockwise direction, whereb a number of insulating teeth, corres ndmg to-the units of a'diglt of the call dnumber, may be brou ht below the spring 6. The dial, bein; en released, is returned to zero b its associated spring. Each time a toot -of dial 4 passes over contact 6, contact fi' is closed and thereafter contact 6 is opened. As a passing tooth frees contact 6, contact 6 will be closed and thereafter contact 6' will be opened. Thus each time contact 6 is opened, whereby a deener'gization of relay PR will be effected, the relay SR will be maintained energized, since the limb s is grounded before contact 6 is, opened over a connection traced through contact 5, coil 3, upper contacts at 1, transmitter 2, and to ground through contact 6; and since the metallic circuit of the line is, with each vibration of contact 6, reestablished before said contact is opened, the relay PR Jwill besuccessively deenergized and energized as dial 4 returns to normal, while-relay SR remains operated. After the last tooth of dial 4 passes above contact 6, the tooth at the extreme left of dial 4 will actuate s ring 5 in such a manner that contact 5 will be closed, whereby a maintaining circuit for relay PR is continue whereafter, contact 5. bein opened, relay SR will be deenergized until t 1e tooth asses over the end of s rin 5 when the dia will be at normal an M stop.. When the tooth passes over contact .5,

said c0ntact,-hy its tension, reestablishes its normal connection and thereafter opens contact 5. Thus, by successive actuatlons of dial 4, the subscriber is enabled to count out the number of the called telephone, each actuation of the dial effecting denerglzations of relay PR, corresponding in number pulses are transmitted .to adjust the first selector H to select the first group of terminals of second selectors, those assigned for connection to the first thousands, whereafter the first selector automatically selects a terminal set of an idle second selector from the group. d

A first selector H includes three sets of wipers 125, 132 and 139. A switching magnet Sl/VM drives these clockwise by virtue of an armature actuated pawl operating upon arutchet wheel fastened to a rotary shaft supporting said wipers. Each actuation of magnet SW'M will cause a long step of the wipers so that each passes over an entire segment 124, 131, 138, respectively. Although but live segments are in Fig. 1 shown associated with each wiper, there will in ract-ice be ten such segments, one for cac group of second selector terminals. Although but three multiple terminals of second selectors are shown associated with each segment, there will, where ten per cent. trunking is provided, be ten terminals for each segment. The normal positions of the wiper contact are between the ninth and tenth groups of terminals. Contacts 126, 134, 140 are, respectively, the private and talking contact sets of second selectors for the first thousand; 127, 135, 141 are like 00114 tacts for the second thousand; 128, 136, 142 contacts for the third thousand, and so on for the other groups. It will be understood that each contact set is multipled at other first selectors H and has connectionsto a second selector 1, with circuits like that shown in Fig. 1. For the clearness in thocircuit'illustration, I have shown each wiper 125, 1 32 and 139 twice. It will be observed from the lower portion of the circuit H that each wiper is provided at each between grou position with a pair of-contacts which are c osed when the wiper is in any betweengroup position, and opened when the wiper first leaves such position. These are. of course group oif-normal break contacts.

Ina'ddition to the mechanism described, the,

first selector comprises merely a single'ofi normal make contact .ON' which, by a simple mechanical arrangement hereafter described, is closed when the wipers leave their position between'the ninth and tenth groups, and is 0 ened when they have com pleted a circle 0 revolution and again reach said positiom- It will be seen that to select the group of second selector terminals 126, 13. 1, 140, the group for the first thousand, one long step for the wipers 125, 132 and 139 is required, whereafter short step travel will be initiated, eachstep causing the wipers to engage a ditfereut contact set 126, 134, 140 until an idle set is reached.

On the denergization of relayPR before referred to, an. impulse of current flows from ground through contacts 99, 98, 119, magnet SVVM to battery Said magnet 'moment-arily energizes and eii'ects a long step of the Wipers up to, but not engaging, the first contact set of the firstgroup. A portion ofthe current transmit-ted, passed through release relayRR' which, by armature 111, looks over wire 107 and contacts 106, 92, togrou'nd, the relay RR now remaining operated until the time of discon nection. After-relay PR energizes, relay SR is momentarily deiinergized and a current impulse flows from ground, through contacts 97, normal contact 100, contacts 123, 113, contacts 146, via wiper 132, alternate contact 110, stop magnet STM, ,busy relay BR, to battery B. Magnet STM and relay BR simultaneously energize, the 'former throwing in a stop to limit the stroke of the armature of magnet SWM, while the latter, by armature115. extends the circ'uitsofiitself and magnet STM' to the seg ments 12 1;" 'Armatu're 1'16 completes a gen erator circuit for the short step winding of magnet SWM which receives current alternations to energize and deenergize it, whereby it is effective to step the wipers 125, 132, 139 over the multiple contact sets of the first group in searchof an idle set. Since busy contact sets will have their contacts 126 grounded,'relay BR will have its circuit continued closed by meansof current flowing to ground through successive busy contacts encountered by wiper 125 untilthe idle set is reached. \Vhenwipers 125, 132,

139 engage the third contact set 126, 134, 140. that of second selector I, assumed to be thatpf the first idle second selector, the circuit 'ofrelay BR and of the ma net STM' will be deprived of ground and th ey will de energize, the opening of contact 116 prevent ing further actuations ot inagnet .SWMC It will be observed that theoriginal energizing circuit of relay PR is opened on the tirst'step of the wipers, since wiper 132 will then disengage the contact pair 1st,), between the tenth and first groups. It is to be noted that the locking relay LGR would beener gized by a portion. of the impulse operating the relay BR, flowing through contacts 113, 112-, and said relay LOR ,in battery, were it not for the fact that the winding of said last-mentioned relay is at first short-circuited by a connection traced through a contact set 147 and Wiper 139. *lvhen the first short step of the wipers begins, the

-Wiper 139 opens contact at 147, removing the short-circuit from relay LOB, which instantly energizes, locking itself by armature 121 to ground over wire 107. By armature 123, said relay instantly opens the path of the current impulse'transmitted by relay SR. Since relay LOR isenergized at the time relay BR denergizes on the selection of an idle contact set, a ground connection may be traced from armature 120, rianormal contact 115, the segment 124, wlper 125- to the engaged contact 1.26 of second selector I, wherebysaid selector will be held busy.

In connection with the operation of selector H, it will be observed that thevsegments 131,138, forming part of the talking circuit, are normally open at alternate contacts 119. 122, so that, while the selector making its long step or steps, no interference, due to battery'potential, will be caused upon already existing conversational circuits with which connection may be made. It. will be further noted that upon the initiation of secondary travel to selcct'contactsfrom a group, the relay BR first energizes, placing segments 131,- 138 on open c1rcu1t at contacts 114, 117 and that only after this occurs can the relay LOB be operated to close the alternate contacts 119, 123. Thus the circuitof the selector of the present in- -vention provides means for positively preventing interference with existing .conversational circuits with which the conductors of the selector may be connected in its opera: tion without depending in any way upon close time relations between the operation of relays or upon relative adjustments of relay armature mechanisms. Q

If the called number were in another thousand, say, the third, insteadof the first, the operation of first selector H would. be like that just described, except that a number of long steps of the wipers corresponding to the units of the thousands digit would be made before theshort'step travel was started.

To select the hnndreds'ot' the called numher, the calling subscriber C again operates his dial 4: until'one tooth is brought below spring andreleases it, whereby, asbefore. relay PR momentarily deenergized and thereafter relay SR. In the present case,

tact 119, Contact lid/the segment 131 for tlre eentacts 134, wiper 132, engagedmrntact lye/normal contact 2l9, winding of switch mitted will units values with those of like group of contacts.

magnet SVVM of second selector I, operating the magnet and causing a long step of the wipers, a' part of the impulse flowing through relay BB which, by armature 211, locks through contact 126, wiper 125, seg- 124, normal contact 115 and closed contact '120 to ground. When thereafter relay SR is denergized, the impulse transbe from ground, through contact contact 100, alternate contact 123, contactl flfa segment- 138, wiper 139, engaged contact 140, normal contact 223, contact 213, the contact pair 246 engaged by wiper 232, alternate contact 210, stop mag- 15 net STM busy relay BB to battery. The circuits of second selector I are like those of first selector H, with the-exception that a contact 216 is added for reasons hereafter explained, Like parts at I have reference numbers corresponding as to their tens and arts of first selector H and the correspon ing electromagnets are designated by reference letters having the exponent 2 instead of the exponent 1, usedwith the electromagnets designated by reference letters in circuit H. The operation of the second selector proceeds upon the reception of the impulses trans mittedby relays PR and SR 111 'a' manner entirely like the operation of first selector H already described, and need not be referred to in detail. It is assumed that the wipers of the second selector I will select the contact set 226, 234, 240, connected to wires 250, 251, 252 extending to the idle connector K, which of course is one of those assigned to lines first thousand, or lines numbered 1100 to 1199 inclusive. The relay LOR serves to extend the talking conductors to the circuits of the'connector K and to operatively connect the ground at contact 220 to the normal contact of armature215, whereby the busy ground is-placed on the private contacts 226 of the selected connector.

Mechanically considered, the construction of the connector K is like that of the first The contacts of a and second selectors.

one hundred lines,

called line group of whicha connector serves, are multiplied at each of ten connectors such as K, in ten groups of ten contact sets each, although in thedrawing but five groups of three contact sets each are shown. As in the case of the selectors, the normal position of the wipers is between the ninth and tenth contact groups. Long steps of said wipers are effected to select the tens value of the called number, each such step moving them over an entire of the connector is indicated at SW'M and the stop magnet at STM After sufficient steps of the wipers have been caused to select the group wanted, the stop magnet is energized to throw the stop and further of the first hundred of the The switching magnet armature 262 locks to ground at actuations of. the switching magnet-are then effected to move the Wipers by short steps to select the individual multiple terminals of the called line out of the selected group.

The calling subscriber C now operates his calling device to again cause one denergization of relay PR, followed by one of relay SR A current impulse will flow on the deenergization of relay PR from ground, through contact 99, normal contact 98, alternate contact 119, contacts 114, 131-132- 134, alternate contact 219, contacts 214, 231232234, Wire 251, normal contact .272, magnet SWM actuating said magnet and moving the wipers 289, 291, .293 one long step in a clockwise direction to a position between the groups, the wipers then being adjacent to the group of contact sets 13, 15, 14, c0n-. taining contacts of lines'numbered 1111 to 1119, followed by those of line 1110, zero being ten impulses. A portion ofthe impulse transmitted over wire 251 flows through locking relay LOR to battery, energizing said relay, locks itself over the wire 250 to groundat contact 220, which is the ground rendering Then the denergization of relay SRtransm-its an impulse of current from ground through contact 97, normal contact 100, alternate contact 123, contacts 117, 138139 140, alternate contact 223, contacts 217, 238-239-240, over' wire 252, through the noW 255, contact 261 and the relay 258 to battery, operatingsaid rela'y. Its armature 259 ener gizes the locking relay LOR, which by oif-normal contact ON, shifted when.the wipers left their normal positions. As soon as the impulse over wire 252 ceases, the relay 258 has the circuit of its locking armature 260 opened and becomes denergized. It will be seen that said relay cannot be re-operated by a later flow of current over wire 252, since the direct connection of its winding With said wir has been opened at con:

' tact 261.

To transmit the fourth digit'of the called number, the calling subscriber now moves three teeth of dial 4below spring 6 and releases said dial, whereby three denergizations of relay PR are caused, followed by one of relay SR. Each denergization of relay PR transmits a current imp ulse from ground over a before traced path to wire 251. Each impulse will traverse the upper winding of switching magnet Sl/VNP, ca 'sing the ergiza'fim will however, effect ashort step only of the switch w1pers, since, on the.

energization of relay LOR", its armature 265 energized the stop rent fiowin through and test re ay TR to ground. Three short tenth and first contact which by armature 254.

energization thereof. Each suel i'enmagnet STM by curnormal contact at 267 steps of the wipers-of connector K will accordingly be made and they will rest engaging the contacts 13, 15', 14, connected with called line C, or line number 1113.

Thereafter a denergization of relay SR transmits a current impulse over the beforeranged to deliver current of varying frequencies to selectively rin an known type Cally spring restored to normal.

of harmonic substation be ls, t ms rendering the system available for selective party line service. The fifth digit of a called number designates the generator to be selected, But 'one substation O is shown connected to the called line,-but three other substations are indicated by their branch connections, which other stations may be like C in arrangement, except that they will have bells tuned to different frequencies. It willbe assumed that 'the substation C is bell-tuned to respondto t e frequency of generator G, so that three steps of the wiper 294 will be required to'select the proper generator. The switch U may mechanically comprise the wiper 294 wit-h the four associated contacts 295. The wiper 294 may be mounted upon the customary rotary shaft havinga ratchet adapted to be driven in the well known manner by an armature-actuated pawl of motor magnet MM. The customary retaining pawl is provided to engage the ratchet as it is driven and hold the same against back movement under the inguence' of the usual restoring spring. A release magnet RM is adapted to withdraw the retaining pawl when it is cner ized, whereby shaft, ratchet and wiper wil be automati- The ofi-nor; mal contacts ON and 0N of switch U are shifted to engage their opposed contacts whenever the switch wiper moved from normal and are restored to their open circuit relation shown when the wiper is thereafter restored to normal.

The calling subscriber C will now operate his dial 4 until three teeth are below 5 springfi and release said dial. whereby three de'energizations of relay PR are efi'ected, followed by one of relay SR. Each dcrmergization of relay PR transmits a current impulse over a before traced path to wire 51., The impulse thence flows through alternate Contact 272, normal contact 270, motor magnet MM to battery B, causing three actuations of said magnet and three steps of wiper 294 to engage the contact of the generator G. Thereafter a curovided with arent impulse is transmitted over a before traced path to wire 252,. flowing thence through contact 255, normal contact 260,

contacts 263, ON, and test control relay TCR to battery, which relay, by armature 268, locks to ground through alternate contact 253 and contact 0N It will be seen that test relay TR has been maintained energized in, series with stop magnet STM" from/the time relay LOR first operated, so that alternate contact 276 of relay TR is now closed. The attraction of armature 267closes alternate contact at that point and then opens the normal contact so that relay TR, while still energized, is connected over. a circuit traced through alternate contacts 267, 276, with ring 288 and via wiper 289 tothe private contact 13' of the called line. If said line is idle, the

cont-act 13 will, as shown, be connected to ground only through cnt'olf relay GO. Thus when the called line is idle, both terminals of test relay TR are connected to' points of like potential an d said. relay be comes denergized, armature 276 then connecting battery A with the cut-elf relay CO of the called line so that said relay energizes and destroys the-normal battery connections of said line. Furthermore, the retracted armature 277 closes a circuit as follows: from ground through constantly operating interrupter 1, generator relay GR, alternate contact 269, normal contact 277, normal contact 285 to battery. Generator relay GR now alternately. energizes and deiinergizes, including and excluding generator (l with and fronrthe called line C, periodically ringing the tuned'bell at the called substation, the ringing circuit being traced from ground, through generator G, contact 295 294, alternate contact 287, contact 292- 293 14, alternate contact 11, limb 8, contact 5 at C, the substation condenser, the lower switch-hook contacts at 1, the call-bell, con tact 6, limb p, the alternate contact 10, con tact 15-.29 1-290,' alternate contact 286 to ground.

- \Vhen the subscriber at C answers the call by removing his receiyer and when relay- GR is 'det nergized, a circuit will be compleicd as follows to supply the substation transmitter with talking battery and for the other purposes hereafter mentioned:-

from battery A the upper winding of answering relay AR, contacts 27]. 275, norma contact 286, over the before traced circuit through limb s of the called line. contact 5,

impedance 3, upper switch-hook co t: ts 1-,

transmitter 2, contact 6, limb 7), hence through normal contact 28 7, contact 279, contact 274,-to the left over wire 252, through the circuits at I and' H. alternate contact reversing relay RV to battery B, whereby relay AR- energizcsand, by armature connects its lower winding in circuit'with the called line, so that battery is" As soon as relay LOB allows armature fed to said linethrough the two windings of said relay. Armature 280'operates ring ing control rela Y RCR- which locks by armature 284 to'ground through alternate con-,

tact 253 and contact OX The opening at contact 285 interrupts the circuit "forinterrupter I so that relay GR remains inert and enerat'or is excluded from'the called line. elay RVat F wasenergized by the How of current last traced through the called substation. On its operation, its armat-ures 101 and 102 reverse the-connections of battery .A and B of the calling line, such reversal being capable of bein used in connection with any of the polarized auxiliary service devices of the art. Armature 103 operated i the relay 94, which, by armature 105, locked togro'und through oft-normal contacts 75 and '76 atthe line selector. Itsarmatur'e 106 opened the connection extending from wire 107 to ground: at contact 92, but said wire still remains rounded through alternate contact 104, c os'ed before the opening of contact 106. By the opening of contact 106', the control of the ground upon wire 107 is rendered possible by relay RV for release purposes hereafter explained.

The two subscribers C and C are now in conversation, the talking circuit thus est-ab- 'lished being traced over the heavily marked conductors from substation C to substation -C, the condensers '95 and9t3 being connected in the circuit at F.

WVhen. the subscribers finish their conversation, they replace their receivers. In case the-called subscriber C does so first, selectors H, I and K will all restore to normal, while'line selector E will remain in connection with the calling line to be restored by the calling subscriber.

Thus when subscriber C replaces his receiver, he opens the conductive circuit at his substation, and answering relay AB is derived of current and also reversing relay V at F. Upon: the denergia'ation of the latter, ground is removed from the wire 107 at contact 10 s, since relay 04 remains encrgized; relays RR and LOR at H now have their locking circuits opened. Upon the deenergization of relay-RR, normal contact 110 is closed and the circuit is completed from battery B in series through relay BR and stop magnet STM, normal contact 110, contact ON to ground. The stop is accordingly thrown in limiting position and arma- -ture 11G closes a generator circuit for the right winding of switch magnet SVVM' and said magnet receives generator actuations, stepping the wipers 125, 132, 139 by short steps in the original direction of rotation until they complete'a circle to the normal point, when contact ON is o ened, delinerj gizing relay BR and magnet TM, and the wipers accordingly come to rest.

120 to retract, ground is removed from the prirate contact'126 at I dene'rgizing relays LOR and RR". On' the deenergi'zation of the latter, a series circuit is established, energizing rela BR and magnet STM, traced through 0 -nor mal contact ON to ground. Second selector I accordingly restores ;in a manner similar to that-of first selector H.

During the restoration the contact 216"is closed, holding ground upon the multiple contacts 126 in order that second selector- 1 may continue busy until itis finally'freed' for further use, when it reaches normal.

Relay AR is of course now deenerg i zedand, upon the retraction of armature 220.81; I, the rocking circuit of relay LOB is opened and said relay is denergizedr ,Thereupona'cir cuitniay be traced from generator through the lower winding of magnet SWNf, normal contact- 257, alternate contactx277, normal' contact 269 (test control rela TCR having had its locking circuit opene by the retraction of armature 253), throu h.contact 264 to ground. Since test contro relayjTCR is deenergized, the series circuitlincludingtest relay TR and stop magnet STM' has been reestablished so that the stop is thrown in its stroke-limiting position" and magnet SVMB causes short steps of wi rs 289, 291,"

293,-i1ntil they complete a circ e ofrotation when contact ON"?- 15 open, deenergiz'ing rela'y LOR, whereby the circuits of magnets STM S WM and'of relay TR areopened.

At this time the connector will be at normal,

since Y upon the dee'nergization of rela LOR, relay RCR had its circuitbpen During restoration, the multiple contacts 226 are grounded at ON? since normal contact 253 is closed. Upon the dene zation ofvlocking relay L0H before descrlbed, the closure'of contact 9.56 to ground operated'release-magnet RM of generator switch U', circuit being traced through contact ON; Said ma net withdraws the retaining pawl of switci U and tlie'wipcrs restore to normal, at which time off-normal contacts ONf andON am opened.

and circuit is opened through'release relay lVhen now. the calling Subscriber replaces i his receiver, rhl'ays PR and SRdeiinergize 'RR. Circuit will then be traced as follows: .from battery, through busy relay BR'of and SR are energized, being re-operetedtacts 73, 74, are opened and so remain until called line sub-group,

the line selector reaches normal. It willhe seen that on the denergizat'ion of relay RR, the relay It at E is det nergized by the opening of .contact 89.90. Said relay remains deiinergized and if, when line selector E reaches normal, relay RR should momentarily rccnergiae upon the closure of contact 73-7 no harm will be done, as relay BR cannot be again energized, since contact 1" at relay R is open.

If subscriber C were to replace his receiver in advance of subscriber C, line selcctor E would restore as just described. On the. decnergizaton of release relay RR, ground is removed from-the wire 107, and lnconsequencc of this, first selector H and second selector I restore to normal in the manner before described. Connector K, however, is notrestored until subscriber C replaceshis receiver, for the reason that the relay AR remains operated until the called subscriber replaces his receiver, and 0 its armature 281 maintains the ground upon wire 250, whereby lockingrclay. LOR remains locked. The ircuits of connector K thereafter remain in their previous condition until'the called subscriber C replaces his receiver, when the denergization of re lay AR is effective. to produce circuit changes, resulting in the restoration to normal, as before described.

Let it new test control relay TCR was energized as before described to connect relay TR with the test terminal 13 of the called line, said line was bus'y. In such case, the contact 13 will have battery connected to it either through a normal contact 2760f some other connector already engaging another set of multiple terminals of said called line, or in case said line has been selected as afcalling line by a line selector I), battery will be connected to the engaged multi le contact 13 over a circuit traceable (re .erring to Fig. 1, parts 1 and 2) via alternate contact 12 of the called line. local wire L. engaged contact 753-432 of the sub-group to which the called line ma belong. a closed contact of the relay R of the the wire L, normal contact 81 to battery A.- cases. the relay TR of the testing connector K will have its terminals connected via alternate contact 267 to-points of ditt'erent potei'itial and said relay will remaih energizcd, whereby the busy signaling circuit of interrupter I will be connected via. alternate contact 266 and alternate contact 278 with wire 252 and the lower talking conduct-or, the busy signal being transmitted over shi lower talking conductor to limb .i of the calling line and .will be heard in the receiver of be assumed that at the time In either of these' 5 through relay PR the called subscriber, the return circuit. lieing traceable over. l mbp, over'thc 11 per talkin conductor and through relay P to ground. Inthis case, generator relay GR remains inert, since alternate contact 277 m 10 mains closed, and both terminals of said m lay are therefore connected to ground. The

.calling subscriber, hearin' the busy signal,

re places his receiver and hne'selector E, first selector H and second selector Irestore in the mannerbefore described. In the present case, connector K also restores to. normal; since no circuit has beenestablished for. answering relay AR and wire 250 depends for its ground entirely u n second selector I. When in the release 0 tsccond selector I, said wiiie 250 is ungrqunded, locking relay LOR denergizes'and the opening of a ternate contact 253 "deprives relays LOR, and TCR of current, whereupon they beoome inert; the 85 opening of alternate contact. 267' 'establisli-" ing a series circuit fortest relay TR and stop magnet STM. The generator circuit for the lower winding of. switching magnet SlVM isnow completed as before, whereby the wipers of connector IQ are restoredto' normal in the manner before described. "On the deenergization of rel'ayLOR, the before described circuit for release magnet RMof generator switch U is completed and the said switch is restored. In connection with first selector H and second selector I, I have provided means whereby, if all theten contact sets of a selected group are busy, the wipers of said selectors will automatically pass over the entire group and a circuit connection will be'established whereby a busy s gnal will be transmitted to the calling subscriber. Thus, in connection with first selcctor H, assume that all the contactsets 126, 134, 140 are 1 busy. Obviously, relay BR would, with the stepping of wiper 125, have its circuit continued closed until the wipers pass over the entire group of contact sets. As soon as they make their eleventh step,

however, to the between-group position,

wiper 125 will be on open circuit and relay RR will be dciinergizcd, allowing the wipers to stop. At this time the wiper 125 will be crossing the contacts 145 between the first and second groups and the busy signal will -be' transmitted to the calling telephone from interrupter I, via alternate contact, 122, contact 125-445, normal contact 117, and alternate contact 123, and over the lower talking conductor to limb .s'. returning over limb 79,

to ground. The callin subscriber, hearing the busy signal, wi thereupon replace his receiver and the 0 werated. selectors will be restored to normal in a before described manner.

It is to be noted from the consideration of the description of operation of the directively'operated switches I I and K, that but three sets of wiper contacts are required and asingle oil-normal contact. In operating switches of this character, the work reqinredgf the switch adjustingmagnet is ofa rather exacting character, as in making'the long steps the magnetsarrnatnre' is required to move through a considerablent-es- For this reason, I have given special attention to producing a circuit in which a. minimum number of wiping contacts is required. At the same time I havddirected my attention to keeping the number of'ofi-norrnal con tacts ata minimum so as to reduce as far aspossible the chances for trouble in that con nection.

It will be noted that in the selectors H and Y I, the busy relayBR and the. stop magnet at the same times. If

STM are always ener ized and detinergized desired, the 'sto mechanism may be actuated-by the busy re ay BB- in each case and the separate magnet. for that-purpose may be dispensed with. I have,

-however, illustrated. separate magnets for these purposes for the reason that I deem,

it preferable not to. have relay contacts mounted directly u on the Selectors.

The contacts 53 for the respective line selectors and their pairedfirst selectors at master-switch D, and the amociated wiper conta'ct 45 connected to the lower winding of relay 27, cooperate to hold an operated switch pair- EH unselectable at the masterswitch until the first selectorH is fully restored to normal.

Thus each contact- 53. is connected by a wire 53- with the contact ON of its respective first. selector, which contact is grounded as long as the first selector is oi normal. -The ground upon contact 51' of a switch pair-at the master-switch of'course holds the switch pair unselectable' till-the line selector reaches normal. ltjwill thusbe seen that until the wiper 45 has its two ends engaging ectively contacts 51', 53' of a switch pair, 0th of whose switches are at- -normal the relay 27 will be maintained operated by currentthrough one or the other winding and the travel of the master-switch D continued.

It will be noted that afterthe operation of a line relay as LR when a line starts a call,

. there is an unguarded interval during which a connector'm'ay make-"connection with the .1ine.as a called line. In such case, a talking circuit is established with the line in .ques-- t-ion and no improper operation is introduced by such an occurrence; a line selector which-may have started merely having its travel continued to afnormal point-J. The method-in question enables me toreduce complexity. that would otherwise exist in the circuits individual to the respective lines.

Preferred forms of,mechan'isn 1s for use in connection with the circuits will now be referred to. In-Figs..-,2 and 3,- 1llustrating apparatus for line selector E, the former figure .shows'a plan .viemwhere in it willbe.

noted that-five groups of twenty contacts each are provided, designated 70", 70, 70 and 70*, between the groups of which are the primary oH-normalcontacts P0", P0", PO, PO and PO respectively, the common segments 58, 58", etc. being mounted in the circular. switch bank directlyabove their respective contacts. The common se ment 60 and contacts 71 extend circulary beneath the contacts 70, as indicated in Fig. 3, and the segment 62 and associated contacts 72 extend circularl beneath the contacts 71. The ofl- norma contact segments 75, 76, are indicated in Fig. 3 directly beneath the contact 72 and it will be understood that the oil-normal segments associated with the wipers ON at E occupy the indicated. arcs in the contact bank horizontal-with the contacts 75, 76, of Fig. 3. I The "arran ements of .the localofi-normal contacts ,O to L0, indicated in Fig. 1, will be associated with contacts 62, 72, in a manner corresponding to that inwhich the coin tacts PO to PO are-associated with contacts 70 and 58 in Fig. 2.

j Thecontact. bank as a whole is built up of a circular base plate 307 and a ring,308 between which the contacts are i-nsulatingly mounted, as shown in the sectional-view comprising the left part of F .3, the contacts and their insulation being, securely clamped between the elements 307and 308. A bridge 30st is bolted to. the bank and to said br dge, and to. the base plate 307, the rotary wiper carrying shaft.3 05 is journaled. .To said sl1 aft, is attached a.hub, carrying the arm 30.6 upon which the ad justable wiper contacts 57, 59, 61 and on are insulatingly mounted. carrying the ratchet wheel 302, is also fastened to shaft 305, and upon one sideof the bankthe motor magnet MM is mounted; whose armature 301 actuates pawl 300 to drive the ratchet 302, shaft 305, and wiper support- 306 rotarily step by step when the magnet-sMM is actuated. 1

Referrin .to the long and short step switch mec iginism shown in Figs. 4, 5 and 6, the, circular bank is in this .case built up in a manner quite similar to that of the previouslydescribed mechanisms,- the contacts being mounted between .a baseplate 361 and a ring 360. Fig. 4;, showing the topview, shows ten groups of contact groups 126,127, 128,'etc., and thebtweengroup contacts 145.; These various contacts.

A second hub,

have the circuit'connections shown-at H.

As indicated in Fig. ;-5, the s ments. 124, 131 and 138 are mounted in di erent levels in the bank and the individual contacts associated with each of the se ments will 'be placed immediately below t em respectively, while the various between- group contacts 145, 146, 147 will he placed in the same levels'with the common strips adapt- I ed to be engaged by the respective wipers 125, 132, 139.

' A bridge 358 is bolted to the switch bank at 372, 373. Upon this bridge are secured 5 the .two electroinagncts comprising the switch magnet SWM', each magnet being provided with a core with a )olc-piecc of the shape indicated at 359 in "ig. 4' at its lower end. Between these pole-pieces, the centrally ivoted armature 350 is adapted to rock, sai' armature having at its opposite ends forwardly extending finger members pproaching'the pole-pieces, but adapted to 11 c ear the same when attracted, whereby a 15 stronginitial pull is secured while provid- ;ing' a lar e range of actuation. The armature, a's sgown in Fig. 5, is preferably lamihated and is rigidly fastened to a shaft 364 which is -journaled below to the bridge 358 and-above to a stud 368 fitting into an orifice inthe bridge. 36? otmagnetic material, -screwed tothe upper end of the cores of the magnet. spools. The armature restoringi'spring 371 has one end attached to the arma- -turelancl the other end to the stud 368. The 'stirrupm'ember 369 embraces the stud 368 aboyeand below the bridge 367'. A screw- 370 isthi ea-ded to the stirrup 369 and, when t-ightened,-cla inps the stud 368 between the "elements 3,67,11nd 369. By loosening the cre y 370, thc slotted stud 368 may be turned crease'ordecreaseithe tension of the p, g'-371'," "iin'd when the proper tension is ""'-,secured,' -'thetightening of the screw 370 will n'iai'ntainthe selected tension of the ar- 1 mature restoring spring. The wiper shaft 362 journalcd 'belowto the circular base plate-361 and above is provided with a bore to receive the reduced end of the armature shaft 364,.the said shaft 362 being thus rota- --table in"'it.s bearings. A hub 363 is screwed to the' shaft 362 and said hubsupports insulatingly the wipers 125, 132, 139. The ratchet wheel 352 is attached"to the wiper shaft 362,:1dapt-ed to be engaged by the pawl 351,1 best shown in Fig. 4, pivotedto. the arm 380. rigidly attached to tlic'arnia ture'shaft- 364. A triangular piece 354 is jolted to the switch bank-and supports the 'stop magnet STM', -whose armature 357 abuts upon a vertically extendinglug 355 (if the piece Said'armature 357, as best shown in Fig. is, when the magnet is inert. beneath the pawlfl so that when the parts .are in this position. each actuation of magnet SY/M' will cause the pawl 351 to advance a long stop until it engages the adjustable stop screw 33G. carried by the piece 354. Each i such longthrust of pawl 351 will of course (lIlVt' ratchet, shaft and wipers a long step. moving the wipers over an entire group of contacts. After the proper group has been selcctrd. the euergization of stop magnet ST'M' attracts. armature 357 so that its end is horizontalwith, and in the path of,-the

step of said wheel, stud 366 frees spring ON 'n anner in whichf-the pawl .35 1

pawl 351, whereafter each actuntion of magnet SVM can drive the ratchet, shaft and wipers a short step only so that the wipers move from one contact set to the next one adjacent. The pawl 353, pivotally mounted upon piece 354, serves to prevent the ratchet from being jarred to retro 'ress when the arm 380 is retracted. Sa i pawl 353 has upon it a pin which projects to engaging relation with the backward extending arm of piece 380. By this arrangement, pawl 353 also serves, in case a partial short step of the wipers is accidentallycaused, to restore thewipers to the. revious exact operating position. 'lhus i a partial short step is pro-- duced, the pawl 353 will not be engaging the adjacent tooth of the ratchet 352 and, when the arm 380 is retracted, it will impact upon the pin of pawl353 and grim-said pawl to "till the en aged tooth o the =ratchet, whereby thcsiaft will lie-drawn slightly backward to one of its operative positions. The oft-normal contact ON"is normallyheld' open by a stud 3G3, mounted. ttpon'ratchet wheel 352. Obviously, on. the first clockwise '90 which then engages its alternate contact and, when a complete revolution of wheel 352 has been completed, said stud again enga' spring and the contact" ON' 1s ;opene.-.- .Iii Fi 0, asectional "detail new shows the pivotally upon the arm 380,"a' s pira spring being provided to press the pawl-351' con sta'ntly inward toward'th'e ratchet wheel 352.,

For convenience, the mechanisms illustrated in Figs. 3, 4 and 5 have been supplied, so far as like. parts are present, with refereuce characters corresponding to those of fiist selector H of Fig. 1. The same-switch mechanism may be employed for the second selectors F and for the connectors K.

It will be seen that I have throughout the illustrations employed common stripseach with a group of associated ad ac ently-.disposed individual contact terminals, with wipers having intheinselves no circuit connections. but which serve, when they are operated, to cross common strips to successire contacts. It is to be noted that a ccinmon strip and a wiper, iii-switches ofJthis character, may be used fora wiper haying a conductor permanently connectedjto it, or connected to it by a brush bearin upon a.:.. conducting element in circuit wit-ht e wiper. 120 Th us where a term such as wiper contact is used in the claims, it is used in the sense of a contact. at the end of a conductor, adapted to be interchangeably connected" with dittcrent terminal contacts,'and is used without reference to whether the contact in question is a movable yiper member In 1tself, or is a' brush or common strip contact adapted to be connected interchangeably with different contacts by means of awiper.

showing battery symbols where convenient.

Thosesymbols, which'have like poles indibe one'source and the symbols B another tive grou cated as grounded, represent batteries of the indicated polarities having the same number of cells or of the same potential. ,They;

may be and preferably are a single source-of current. Thus the various symbols A-may source. It will be obvious that the invention de' scribed in this, specification and pointed out in the claims may be modified and applied in various systems without departing from my invention, which is accordingly not to be limited in these respects.

I claim as my invention 1.,A;selective mechanism' for automatic:

exchanges including terminals arra'nged'in groups traveling. contact .means, one for each' group common to its group, electromagnets, one for each group, said'electrG magnets being adapted to be selectively energized, and each controllingva switch contact.

connected to the contact; means of its respec- 2. A se ector for automatic exchanges in eluding terminal contacts arranged in groups, wiper contacts, one for each ofsaid oups, electromagnets for said selector, one or each group, and .clrcult means for operating the magnetof a group to 'render the re'sapec'tive wiper contact live"? oroperative. A selector for automatic exchanges including --termin al contacts arranged in groups, wiper contacts, onefor-each of said roup's, electromagnets forsaidselector, one or each group, circuit. means for operating the magnetiof a group to render the respective wi er. contact 11ve' oroperative and means or preventingmore thanone of said.

3 magnets beingenergized at fone time.

wiper contacts, one for each 0 groups,'wiper-contaots, one for each of said groups, elect-romagn'ets for saidselecton one for. each group, a telephone line, and means controlla 1e by current thereover for operat-.

ing the magnet of a group to 'alter the op-' group, a telephone line, means controllable by current thereover for o crating the ma'g net of a group to alter tie operative rela-' tion of the wipercontact of-saidmagnet, and means for preventing another magnet being operated after one is'o'perated.

6.. A telephone system including telephone I l'ines,mu'lt1ple terminals therefor arranged 35 in groups whereby said lines are in corresponding groups, a selective switch for selecting said terminals having a wiper con-,

tact for each said .group, magnets for said sw1tch,-one for .cachgroup of lines, and

energize t e magnet 'of a'particulargroup its circuit relation 'altered.

lines, multiple terminals therefor arranged in groups whereby said'lines are in corre-I sponding groups, aselective switch for selectin "said terminals havin'gfa wiper contact oreach said roup, magnets for said switch, one for each group of 'lines', means responsive to. current over a line to energize 't-hemai net of a particular groupxwhereby thewi er contact ofthatgroup has its circuit' re ation altered, and means preventing energization of r p r e t a (K -8. Ajtelephone system including .telephone lines, multiple .terminalstherefor arranged 'groups. whereby said lines are in"co'rre'-' spon'din'g groups, a selective switch for sesaid terminals having a. wiper conresponsive to current over a.v line to energize .cuit connections: controlled by said magnet the wiper contactof the r ective group.

, 9;. A- telephone'sys'tem inc in groups'wher'eby said lines are in corre-' sponding groups, a selective switch for'selecting said terminals having; wiper contact for eachsaid switch one for eac group 0 lines, means magnet for second group, whereby operation of a group" relay group groups whereby lines are in correspondwhereby the wiper contact of that group has lectinfg tact or each saidroup, magne ts for said switch; one for-.eac -group .of lines, means for. operatively extending the connections of uding telephone lines,fmu lt1ple terminals therefor arrangedroup', magnets for said' responslve tocurrent over a line-to energize.

the magnet of a. articularv cup; circuit p connections contro led. by sai 4. A telephone system including a selectoroperatively extendinglthe connections of the having terminal contacts arranged -in .wiper ioontactlofthe'respective group, and

terminals having wiper coni normally extending .from eachsaid group relay to the elect-romagnet of the respective willenergize the corresponding magnet to render operative the wiper contact of ts 1i;- A telephone system including telephone lines, multiple terminals therefor arranged in means res onsive'to current over aline to 7. Atelephone system including telephone a second magnet after one is the magnet of a particular group, and cir-

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