US1144407A - Telephone system. - Google Patents

Description

- A. H. DYSON; TELEPHONE SYSTEM. APP L|CAT|0N FILED NOY- 7, F5506. RENEWED SEPT. 27. 1913. 1,144,407,

Patented June 29, 1915.

5 SHEETS-SHEET I A. 'H. DYSON.

TELEPHONE SYSTEM. v

. APPLICATION FILED NOV-7,1906. RENEWED SEPT-27,198. 1,144,407.

; Patented June 29,1915.

5 SHEETS SHEET 2.

A. H. DYSONF TELEPHONE SYSTEM. APPLICATION FILED NOV-J, I906- RENE WED SEPTQQ], I913. 44 407 V Patented June 29, 1915.

5 SHEETSSHEET 3.

A. H. DYSON TELEPHONE SYSTEM.

I APPLICATION FILED NOV. 7. 190a. RENEWED SEPT-27, 1913.-

Patented June 29, 1915.

5 SHEETS-SHEET 4. V

h v Maw a.

A. H. DYSON.-

' TELEPHONE SYSTEM. APPLICATION FILED NOV. 7. 1906- RENEWED SEPT.2], 19l3 Patented June 29, 1915 citizen of the United States, and residing Iiili D g rias Parana OFFICE.

ALFRED EnYsoiv, OECHiCAGO, ILLINOIS, ASSIGNOR, nYiirEsNE ASSIGNMENTS, T KELLOGG svrrrcnnoann esurr'w COMPANY, A CORPGRATION OF ILLINOIS.

TELEPHONE sYs'rEM.

menace.

Application filed'iiovember' 7, 1909, Serial No. 342,355. Renewed September 27, 1913. Serial No. 792,223.-

Be it known that I, -ALFRED H. Dyson-, a

at Qhicagc; county of Coolr, and State of is have invented certain new and usei ul' .mprovements in Telephone Systems, of

which the following is a specification.

The present invention relates to automatic telephone exchange systems of the type in which calling and called subscribers lines-are united for conversational purposes through the vagency of link-circuits and elec-- trica-lly actuated switches controlled by ourrent impulses over the calling line. In sys- 15 terns of this type, the electrically controlled switch which is first set in operation upon the initiation of a call is so constructed that it has access to a plurality of link-circuits to which the line: circuit may be extended. In the system which I employ, this switch is set in operation uponthe removal of'the calling partys receiver from its switchhook, and one object of my invention is to provide means for notifying the calliiig party. by a characteristic signal, of the busy condition of all of the link-circuits available to his line. Preferably this signal is transmitted to the calling party before he operates his substation call mechanism, so that he is promptly advised of the impossibility ofobtaining a call at that time.

In systems of the type indicated. the electrically controlled switch'which is last set in operation to complete a connection be tween calling and called lines, commonly called a connector switch, and which includes active contacts and a plurality of associated passive contacts. usually has one set of passive contacts for each line. In case a number of lines run to telephones acjcup'yiigg the same location or to a private exchange board. it is necessary to assign one Y number to each line and it is therefore neces- Figs. 6, 7

tor switch, each viewed froma different condition of an of these lines will be ade known to the calling party.

Patented June 29, 1915.

Another' object of my invention is to pro- .vide the improvements above indicated with a. minimum number of, relays and other parts, While maintaining satisfactory efficiency in operation and economy in construction, installation and maintenance.

These and other objects and features of my invention will be more fully understood upon reference to the following detailed description taken in connection with the accompanying drawings, and the scope of the invention will be particularly pointed out in the appended claims. 4

Referring to said drawings, Figure 1, which includes parts 1 and 2, isa diagram of a system constructed in accordance with my invention; Fig. 2 is a partial sectional view of a selector switch employed in the system illustrated and illustrating in plan the primary magnet and its associated parts by which the switch is given its primary movement, the section being taken on a plane indicated by the line 2-2 ofFig. 7 Fig. 3 is a detail of the cit-normal switch associated with said selector switch; Figs. i and 5 are front and side elevations respectively of the individual switch;

and 8 are elevations of a selecside; and Figs. 9, 10 and 11 are similar views of a connector switch employed in the system. Throughout these figures. like characters refer to like parts;

In the system which I have chosen to illustrate the application of the features of my invention, the substation equipment, designated generally A, is united byline limbs S-P to the active contacts or wipers of an individual switch B. and the passive contacts of a plurality of connector switches C at' the exchange. The passive contacts of the individual switch are connected to a plurality of link-circuits LL running to the active contacts or wipers of a first selector switch D whose passive conswitches C. Inan eschange having ten thousand subscribers lines and constructed for ten per cent. trunking, the number of switches employed would be as follows: ten thousand individual switches 13, one thousand first selector switches D, one thousand second selector switches E, and onethousand connectorswitches C. With this apportionment, each line would bemultipled to the passive contacts of ten connectors, each connector to one hundred second selectors, each second selector to one hundred first selectors, and each first selector to ten individual switches. It is of course to be understood that where an ultimate capacity of only one thousand lines is desired, one set of selector switches may be omitted. It should also be understood that the above figures are merely typical and may be modified to suit'ditl'erent conditions.

In operation, the calling party removes his receiver from its switch-hook and thereby sets the individual switch 13, associated with his line, in operation to automatically seek out and establish connection with an idle link-circuit L-L The calling party then operates his call apparatus to transmit impulses correspondingto the digits of the number of the subscribers line with which connection is desired. The first of these operates the first selector D associated with the selected link-circuit 11-14 to pick out anidlelink-circuit L -L extending to a second selector E associated with the'thousand group to which the called line belongs.

The second set of impulses operates the. second selector E to pick out an idle linkcircuit L -L extending to a connector as sociated with the hundredfgroup to which the called line belongs. The third set of impulses operates the connector to pick out that group of ten contacts to which the called line belongs, and the filial set of imcalled l'inccontacts in that group.

,pi1lses ;cai1ses the connector-to pick out the The individual switch B comprises active contacts or wipers 10-11-12, cooperating with corresponding bank contacts 13-14-15. and actuated by a motor magnet M.

The first selector D comprises the active contacts or wipers 16-17-18, which oooperate with the corresponding bank con tacts 19-20-21 in making connection between the link-circuit strands 11-11 and Il -If respectively. The wipers are given both a primary and secondary movement in response to the energization and dednergi- 'zations of the primary magn'et'PM and the secondary magnet SM respectively. By the primary movement, the wipers 16-17- 18 are moved step-by-step to a desired group of passive or bank cont-actslQ-QO-Ql, and by the secondary movement they are moved automatically over contacts of the selected group until the contacts of an idle link-circuit L 4 are encountered. The second" selector E is similarly operated by me a'ns 9f j 'its associated first selector.

its primary magnet PM and its secondary-v magnet SM to move its wipers 22-23-24.

into engagement with the corresponding passive or bank contacts. 25-26-27 of an idle-link-circuit 'L -L extending to an idle connector C. In a similar manner, the connector C is operated by its primary magnetf PM and its secondary magnet SM to move station A at the right'of said figure and that the latter party has three telephone lines running to his station to which have been assigned the number can, the party at the former station first takes down his receiver and by that act sets the individual switch B,

automatically select an idle link-circuit and The removal of the receiver 34 from its switch-hook 35 com- S-P through the transmitter 36 and the normally closed contacts37-38 of the call-:

ing device'39. At the same time, thewipers 11' and 12 of the individual switch are in engagement respectively with the grounded contact 14 and the contact 15' which is per--- manently included in circuit with the wind ing of the control relay 4:0 of said switch and the battery B. Since the line limbs P and S are normally continued through the contacts of the cut-off relay CO to thewipers 11-12, it follows thatras soon as the calling party removes lllS receiver, CllQult is 40 to move the armature contact 43 to its." closed or grounded position, and the armature contact 44: to its alternate position." The closing of the contact 43 completes a' associated with his line, into operation to pletes'a bridge between the two line limbs I completed from the live pole of the battery circuit from the live pole of'the battery B through the winding of the motor magnet- M, which automatically interrupts its own? circuit at the contacts 45-6, and, through. the agency of the mechanism associated;-, therewith and illustrated in Figs. 4 and 5,"

steps the wipers 10-11-12 of the switch over the associated bank contacts. The bank contacts 14-15 areof sufficient length to remain in engagement with the wipers lllagnd 12 respectively after they have heel; moved 'qne' jstep, while the {tact 13? ,iwhich cooperates with is not e gagedtthereby until greener the switch has taken one step. Upon the .first step of the individual switch B, the contacts oi the release switch RS and of the primary oli normal switch P0 are moved to their alternate positions, the spring contact it? moving out of engagement with the grounded contact 8 and into engagement with contact 4.9, while the spring contacts 50 and 51, which are normally in engagement, are disengaged and moved into engagement respectively With the cont-acts 5i2-53, thelatter of which is grounded. Thereupon, a circuit is completed from the live pole of the battery'B through the winding of cut-oii'rclay Ci), contacts 5152 of-the primary cit-normal switch PO, contacts 41-19. of the release switch RS, and

contact 43 of the control relay 40 to ground.

At the sametime. the engagement of the olfnormal contacts places ground upon the passive contacts 32 ot' the various connector switches to which the line is multiply connected, thus establishing a condition which upon test by any connector switch, will prevent connection with the line. i

The closing of the circuit through the cutoil relay CO, causes the movcmentcf its ,armature contacts 21 E. to interrupt the normal connection of the line limbs P-+S to the wipers 1112, and thereby prevent possible interference with conversation over busy link-circuits having multiple contacts over which'the wipers 11-42 are required to pass. Since the breaking of this connection interrupts the original circuit through the Winding of the control magnet 40. it is necessary to provide a maintaining circuit for this winding. The original energizing: circuit for the relay 40 exists long enough to permit the motor magnet M to advance the wipers l01112 one step. Thereupon the relay 40 is'maintained energized by a circuit extending from the live pole of the battery B through the winding of said relay. alternate contact 41. wiper 10. and contact 13 to ground. Consequently. the magnet 40 remains energized at the time the wipers are inthcir second position and through the continued operation of the motor magnet M, the wipers are stepped to their third position in which they engage the first set of contacts 13H15 respectively. If the link-circuit connected to these contacts he in use.' a multiple of the contact 13 will be connccted to ground through the wiper 10. normal contact a l and the wind ng of release magnet PM of another individual. switch. Consequently. the circuit of the control relay 40 will l'ic maintained and the wipers will he moved another step. This step-bystep movement will continue until the wiper 1d engaucs a contact 13 of an idle link-circuit. lfpon such engagement. the circuit through the control relay l0 will be opened and its contacts 13 i--t will return to their retracted positions. the former interrupting the cirsponding" to the selected linlccircuit L-L'-'.

To maintain the drawing, within bounds. the linlccircuit L-L is shown multiply connected to only two individual switches B and only one of each of the link-circuits LL L -lr and Ii -L is shown.

New in accordance with one of the rum. tures of myinvention, one set of passive contacts coiiperating with the wipers 1011-12 and preferably the last set to he engaged, is not connected to conductors of the link-circuit, but to a busy-back mechanism F and to control relays vBy this mechanism a characteristic signal is transmi tted to the calling party in case all of the link-circuits LL available for connection to his line are in. use and the release of the actuated individual switch is placed under his control. Since. the operation of the switch occurs in response to the removal of the receiver 34 from its switch hook 35 at c the substation, the calling party will be advised of the busy condition of all of the linkcircuits L-L before operating his call device 39, as in this operation, as soon as the wipers 101112, engage the contacts 13'-14 15 a circuit for thetransniission of the busy signal is completed as follows: The primary circuit extends from the active or nngrounded pole of the interrupter 56 through the primary winding of induction coil 57 to the active pole of the battery. B; the secondary circuit extends from one terminal of the secondary winding- 57. through condenser 58. contact 15 wiper 12. line limb h. contacts '3837 at the substation. transmitter primary winding of the induction coil 59. hook switch 35. line limb P, wiper 11. contact 14 winding of relay 5i to the other terminal of the secondary winding of the induction coil 57; The potential induced in this secondary circuit by the primary circuit including thcinterrupter 56. produced a similar ctlect in the local circuit of the receivcr- 3% with the consequent buzz as an indication to the calling party that he cannot obtain connection at that time. If in response to this signal hc hangs up his re cei er '34, he will momentarily ground both l the receiver, an insulating projection 63 on the switch-hook passed over the upper end 1 of the spring 60, and now upon the down- I a circuit device 39, the circuits ing mechanism 39 will cause the extension of the calling operation on the part of ward movement of the switch-hook, this pro- ]ection by pressing against the spring 60,

brings it and the springs 61-62 into engagement, and then slips over tim end of the spring into the position illustrated. The

spring 62 is grounded so that by this replacement 'of the receiver upon its switchook, both line limbs are momentarily grounded. This momentary grounding of the line limbs completes a circuit for each of the relays 5455, which, in the case of the relay 54, maybe traced from the live pole of the battery B through the winding of said relay, contact 1 1 wiper 11, line limb ,1, contact springs 61-62, to ground; and in the case of relay 65, from the live pole of the battery B through the winding of said relay, contact 15 wiper 12, line limb S, contact springs 6061-'62 to ground. The simultaneous energization of the relays 54 55 through the agency of the wipers 6 2 -66, and contact springs 66-67 which are thereby forced into-engagement, completes for the release magnet RM which may be traced fromthe live pole of the battery B through the protective resistance 68, contacts 6766, contact 13 wiper 10, normal contact 44, and winding of release magnet RM to ground: As will be hereinafter more fully pointed out, the momentary energization of the release magnet RM causes the restoration of the wipers 10-11-12 and the associated parts, to normal position.

I case all the link-circuits L---L were in use at the time a party called, and such party failed to put his receiver to his ear and thereby did not obtain the busy indicat'ion until after he had operated his calling would remain substantially the same until he had placed his receiver to his ear with the expectation of receiving a reply of the called party. Upon getting the busy indication at this time, he would then hang up his receiver and the actuated individual switch would be restored, as just described. In case the individual switch establishes connection between the calling line and an idle linkcircuit 11-13 the subsequent operation of the call the calling subscribers circuit. Since it is I assumed that the number of the telephone of the party wanted is 3451, the next step in the calling party, will be to move the dial'69 of his call device 39 until three of the teeth 72 (correspondimg to the thousands digit in the number 3 151) pass below the contact spring 73 and then allow itto return to normal under the tension of the spring 74.

-the substation ground at 76.

wiper 12, line closed three times, and this will'be followed by a single closure of the contact spring 75, since in the normal position of the dial 69, one tootlrlies below the spring 75. The three closures of the spring 73 send three impulses of current over the line limb P, while the single closure of the spring 7 5 sends a single impulse over the line limb S, both being efiected through the agency of At the time these impulses are being transmitted, the bridge through the transmitter 36 is interrupted at the contacts 37.38 which separate when the dial 69 is moved from its.-..

normal position. The three impulses transmitted over the line limb I, energize and deenergize the primary relay PR associated with the first selector D three times, while the following single impulse over the line limb S energizes and de'e nergizes the secondary relay SR, once. The circuit over which the impulse is transmitted in the case of the primary relay I pole of the battery B, through the winding of the heat coil H, the winding of the pri-,

mary relay PR, closed contacts 77787 9, linkcircuit strand L, contact 14, wiper 11,

line limb P to ground at 7 6; and in the case:

of the secondary relay SR, from the live pole of the battery through'the heat coil, the

PH, extends from the live winding of said relay, closed contacts 80 81-82, link-circuit strand L contact 15,

limb S, to ground at 7 6.- Each impulse transmitted through the primary relay PR causes a corresponding impulse to be transmitted through the pfimary magnet PM of the first selector D. This circuit may be traced from the live pole of the battery B, through the heat coil, the winding of primary magnet PM, closed contact 83 of the release magnet RM of said selector,

closed contacts 84: of the secondary off-normal switch S0 of said selector, and contacts 65 S6 of theprimary relay PR to ground. The selector switch, as previously indicated and as will be more fully explained hereinafter. is so constructed that its wipers 1617-1S are given a primary movement in response to these current impulses, and are thereby brought opposite a group 0 bank contacts connected to a corresponding group of second selector switches. Inthe present case, the wipers, due to the three primary impulses, are moved to the third group of bank contacts which are assigned for connection to the third thousand group of subscribers lines. over the line limb S which follows the three impulses over the line limb P, and which we have seen, momentarily energizes the secondary relay SR, closes a moifiantary circuit from the grounded contact 86 of said relay, hrough contact 87, closed contact 88 of the secondary off-normal switch S0, the winding of the. private relay 89 to the live The current impulse I pole of the battery, thereby energizing said relay 89 to open normal contacts 90-91, to

close normally open contact 92 and to move contact 93 from its normally closed position to its alternate position. By the first primary movement of the selector D, the

contacts of the primary ofi-normal switch PO and the release switch RS? are moved; contact 9% to connect with ground, contact 95 to move from engagement with contact 96 into engagement with contact 97. Consequently, as soon as private relay 89 is energized current will flow overs circuit including the winding of the secondary magnet SM, its vibratory contacts 98--99, alternate contact 93, contacts 97-4)?) and closed con tact 9% to ground. The magnet SM, by reason of its vibratory circuit and mechanical connection with the wipers 161718, as hereinafter more fully explained, steps said wipers over the coiperating bank contacts 19 20 -21. 1

As soon as the circuit of the private relay S9 is interrupted, its contacts are returned to their normal positions; consequently, the circuit of the secondary magnet SM is interrupted and the further movement of the wipers in. a secondary direction ceases. Upon the first secondary movement of the wipers l61718', the contacts Se-88 of the secondary ofi-norm al switch S0 are broken. Consequently, the initial energizing circuit of private magnet 39 is interrupted, and in order that the wipers may not stop on busy contacts, an energizing circuit for the private relay must be maintained. This circuit extends from the battery through the winding of said relay, closed contact 92, normal contact 100, wiper 1b, to ground. The ground connection of thewiper 16 extends over multiply connected contacts 19, the wiper 16 of another switch, normal contact 100,v normal contact contacts .9'T-9F*, and closed contact 9i to ground. Thus it will be seen that as long as the wiper I6 is passing over contacts ascocia-ted with busy link-circuits, a circuitwill be" maintained for the private magnet 89,,asnd in turn, a circuit will be maintained by said magnet for the sec ondary magnet SM by which the switch is given its secondary movement. As soon however, as an idle link-circuit is encountered, this maintaining circuit for the magnet 89 will be interrupted and the further movement of the switch wipers stayed, thus completing connection from the calling station over the heavily marked circuit including link-circuit strands LL'-, L' -L to the wipers 232''t of an idle second selector switch E. time, the link-circuit strands are interrupted at the contacts 79l0l-821-O'2. In the operation of the selector D, it will be observed that the wipers 17 and 18 are dis- It will be observed that at this.

connected, as just indicated, at contacts 90-91 of the private relay 8? while passing over the contacts 2021 of busylinkcircuits." By this means, interference with conversation through contacts in multiple with the contacts 2.0:-21 encountered by the wipers l7 and 18, is prevented.

The next step in the calling operation consists in again moving the dial 69 at the calling station, far enough to bring four teeth (corresponding to the hundreds digit in the number 3451) below the contact spring73, and then allowing it to return to normal, thereby transmitting four impulses over the line limb P to. actuate the primary relay PR four times. This, as before, will be followed by a single impulse .over the line limb S which will actuate the secondary relay SR, once. These impulses will. cause the second selector E to move its wipers 22-2324l to the fourth group of bank contacts 252627, which group is assigned for connection to the fourth hundred group of subscribers lines, and thence into engagementwith an idle link-circuit connected with an idle connector C having access to the called subscribers line. The four energizations of the primaryrelay PR. cause four closures of a circuit from ground at the contact 86 of said relay, through contact S5, closed contact 90, wiper 17, contact 20, closed contact 104 of the secondary 0flswitch RS to more to its alternate posh tion'. The impulse transmitted by the secondary relay SR will close a circuit from ground at contact 86 through contact 8?, closed contact 91, wiper l8, contact-21, closed contact 309 of the seconc'lary oil-normal switch S0, through the winding of the private magnet to the live pole of the batteij' B thereby energizing said relay ill and causing it to ,disconncct wipers Q) t so A from circuit by opening contacts 11l-1l2, whileat the same time, closing I contact 113 and moving contact 11% from I its normal to its alternate position. By the movement of the latter contact, a circuit is completed for the secondary vmagnet SM which may be traced from the live pole of the battery B through the winding of said magnet, its vibrator contacts l-l 5 -116,.al-j

ten-late contact 114, alternate contact 108,

and closed contact 107 to ground. By reason of the vibratory character of this circuit, the secondary magnet SM" will step thewipers around over their associated bank contacts until its circuit is interrupted. This occurs, as previously indicated in connection with the description of the first selector D, when an idle link-circuit is encountered. At this time, as previously indicated, the wipers 28-2d are again included in circuit, thus projecting the circuit of the calling line to a connector C. In this connection, it may be noted that the maintaining circuit for-the private magnet 110, while the wipers 22-2324: arev passing over the contacts of busy link-circuits L L extends from the live pole of the battery B? through the winding of said relay, closed contact113, normal contact 117,

the wiper 22 to ground. This ground connection as before, extends-through multiply connected contacts 25, the-wiper 22 of an- .other second selector, normal-contact 117 of its release magnet RM normal contact 114, alternate contact 108. and closed,v contact 107 to ground.

The next step, inthe calling operation consists in moving thedial69 at the calling stationinto' a position to transmit five impulses over the line limb P through the primary relay PR, followed by a single impulse over the line limb S, through the secondary relay SR. Thefive primary impulses (corresponding to the tens digit in the number 3451) are extended from the primary relay over a circuit extending from ground at said relayto the wiper 17 of the first selector 1), as previously traced, thence through link-circuit strand L wiper 23, contact 26, normal contact 118, closed contact 119 of release magnet RM associated ianne? taryenergization of the secondary magnet SM which is instrumental in advancing the wipers one step in their secondary direction. As indicated in Figs. 9 to 11 inclusive,

the Wipers are normally two steps distant switch.- This'is to prevent the above see- The next ondary impulse, or a portion of it, from being transmitted through the winding of the relay 125 b way of the normal contact 126 of relay 12 and normal contact 128 of relay 123,, which might occur if contact 121 were :atonce thrown over to its alternate.

Position. I 4

step in the calling operation consists iniagain moving'the dial 69 so as to transmit one primary impulse (corresponding to the units digit of the number .3451) with the selected connector, winding of the.

primary magnet PM to the live pole of the battery B In this instance, the five impulses of current transmitted through the primary magnet PM will step the Wi ers 28-2930 of the connector to thefth group of 'bank contacts 313233, to which subscribers lines having numbers between fifty and fifty-nine inclusive, are adapted to be connected. Upon the first movement of the switch in response to the primary impulses, the contact 120 of the primary ofi-normal switch P0 is closed, thereby grounding the associated bank contact-25 through the winding of release magnet Elvi The secondary impulse following :these five primary impulses, closes a icircuit from ground at the contact 86 of the .secondary'relay SR, to the wiper 18. of the thence through linlz-circuit strand L wiper 241, contact 27, normal contact 121,

closed contact 122 of relay 128, closed contact 124: of release magnet RM winding of the secondary magnet SM to the live pole of the battery B -This causes a momenfirst selector switch I), as previously traced;-'

again followed by. a single secondary impulse. In this case, the circuit under the control of the primary relay PR is the same as that heretofore traced, as far as contact 26; thence it extends through alternate contact 118, contacts 129 -130 of relay 127, closed contact 122, of relay 123 closed contact 124: of release magnet the winding of secondary magnet SM to the live pole of the battery B thus, the

secondar'y ma'gnet is energized andideenergized once, thereby stepping the wipers 282930 into. engagement with thefirst set of contacts in the fifth group, thus 'estab-- lishing connection with the bank contacts V 313 2- of one of the lines running to substation-.A shown at the right in Part 2 of Fig. 1. The secondary impulse which follows the single primary impulse, is extended by'the secondary relay SR to, contact 27 of the second selector E over a path the same.

as that heretofore traced. From this point its circuit is continued through alternate contact 121, normal contact 126, normal contact 128, winding of relay 125 to the-live pole of the battery B The completion of this circuit momentarily energizes relay125 to close its contact 131. In ease the first line running to the called partys station is in use, we have seen that-its contacts 32 will be connected to ground by way of the contact 50 of its off-normal switch, PO associated with that line. Consequently, if

this particular called line be busy at this time, a path for current will be closed by the movement of the contact 131 which may be traced from the live pole of the battery 100 Bil l and areaear B through relay 123, closed contaca131, normal contact 132, normal contact 133, wiper 29, and-contact'32 to ground. At this point-it may be mentioned, that-by reasonot' the mechanical relationof the relay 125 and release magnet BN the contact 132 is moved to its alternate position upon the re lease of relay 125 and subsequently returned to its normalposition upon the energization of release magnet EMF. The closingof' the circuit ofrelay 123 causes it to open its-contact122, to close its contact 134 to ground, to close its contact 185 and' to move its con tact 128 to its alternate and groundedposition. In the movement of. the contact-.128

' to its grounded position, the alternate contact is made before the normal contact-is broken, consequently the relay 125 is maintained energized, the. former circuit being over the line limb S and the latter through alternate contact 128 to ground; The 010- sure of contact 135 completes a locking eircuit for relay 123 which is independent'of the contact 131 of relay 125.

As previously indicated, the connector is specially connected forthe purpose of carin: for calls for parties having a plurality of lines running to the same location. Thus,

in the illustration chosen, the first three contacts 31-3233' are assumed to be connected to lines extending to the location of the equipment A at theright in Fig. 1. If, now, the first of these lines is found to be busy, it is necessary that the wipers be stepped into engagement with the second to see if it is busy, and then if that be busy,

into engagement with the third, and if that also be busy; the calling party must be apprised of'the fact. The closing of the contact 13-1 of relay 123 accomplishes this result by energizing the secondary magnet SM? The encrgizing circuit for this magnet extends from the live pole of the battery :8 through the winding of the magnet, its vibratory contacts 13G13T, closed Contact 131 to ground. By reason of the vibratory character of this circuit and the mechanical relation of the parts, wipers 2S2930 are given one step in a secondary direction, and if the second line is in use, the circuit of the relay 123, and consequently that of the secondary magnet SM will be maintained. If an idle contact 32 is encountered, the circuit of the relay 123 will be interrupted .since the contact 32 or" an-idle' line will be disconnectedfrom ground. If no such idle lineis encountered, the wipers will he stepped into engagement with the fourth set of contacts 313233. In the present case, these are the busy indicating contacts over which the busy conditionof the three preceding lines is made known to the calling party. ll'hcre but a single telephone line runs to a subscribers station, it must be followed by such a set of contacts. As soon as such a set ofcontact-s isencountered,the locking eir tact 134 interrupts the circuit of the secondary magnet 8M and thereby prevents fuhther movement of the switch wipers.

Thereturn of contact 128 to normal interrupts the circuit of relay 125, and'as previously stated, upon the deenergizationof this relay, contact 132 is moved to its altern-ate position. At the same time a groundis thrown upon wiper 30 so that an energizing circuit is completed for relay 139 and its contact 133 is-moved to its alternate posi tion, thereby completing a circuit for relay 127"; which may be traced from the live pole of the battery B through protective resistance 140, alternate contact 133, alternate contact=132 and the windingof'the relay 127 to ground. The energization of relay 127 moves its contact 126 to its alternate position tothereby unite portions of the strand L and disconnect the Winding of relay 125 from said link-circuit strand. The energizationof this relay also connects adjacent tact 129 to its alternate position. At this time a possible circuit from the strand L through the winding of secondary magnet SM is prevented .by the separation of contacts 129130. The energization of relay 127 also closes contact .1-11 to ground. As soon as this takes place, a circuit is completed through the winding of the ringing relay 142 over a path extending from the live pole of the battery through the winding of said relay, normal contact 144, closed contact 111, to ground. The energization of relay 14-2, by means of contact 1-.l5,connects a source of ringing current to the strand L This connection extends from the grounded generator HG through the in terrupter 147 which alternately connects the strand to ground directly and through the generator, the winding 148 of relay 149 and closed contact 145 to strand L This con nection of the generator to the strand L 4 performs no useful function at this time since there is no closed circuit through the substation, but as the interrupter 147 ro tates and alternately connects the winding 148 to ground, the relay 149 will be energized by current from the live pole of the battery through the protective resistance 150, engaged contact 31, wiper 2S, closed contact 145, winding l l-S to ground through the interrupter 117. The relay 14 9 being thus energized, connects the normally dis connected adjacent portions of the strands l'fL by means of its contacts 151-152 and through the agency of its contact 153 moves contact 1% from its normal position thereby making contact Ill-153 and subsequently breaking normal contact 141. The

engagement of these contacts completesa locking circuit for the relay 149 which extends from the live pole of the battery B through the upper Winding of said relay, contacts 153144, and closed contact 141 to ground. The relaysv 127-149 being new energized, a secondary circuit for-the busy back interrupter 155 is completed from one terminal or the condenser 138, through engaged contact 32, Wiper 29, link-circuit strand L, condenser 157, ,and thence over the heavily marked circuit to the substation viaclosed contact 91 and condenser '103, and thence returning over the line limb P, link-circuit strand L, alternate contact 78, upper windings of relays 170-169, heat ,coil H, battery B to ground, and thence through battery 13 to the other terminal of the secondary Windingvof the induction coil 156. As before indicated,rthe potentialinduced in this circuit produces a busy buzz in the calling partys receiver as an indicatacts 31-32 to the line limbs S and P respecti ely, and the latter. among other things, to successively close a circuit for relays v 142 and 149 via closed contact 141, as previously traced. \Vipers 28 and 29 now being in circuit with the line limbs S and P, the

- through the hook-switch 35, call-bell 15S,

actuation of relay 142 connects ringing current generator 146 and the interrupter 147 to the wiper 28, and a ringing circuit is completed from said Wiper over line .limb S condenser 159, line limb 1?, contact 32, Wiper 29, closed contact 160 of relay 142, resistance 161 to the live pole of the battery B During the. application of this ringing current, battery is supplied to the wiper 29 over a path extending from the bye pole of the bat-" tery B through protective resistance 161 and closed contact 160. By, this connection, current is supplied to the relay 127, in multiple with the vWinding of cut-off relay CO, to maintain it energized. The actuation of the cut ofl' relay CO in addition to connecting the contacts 31-32 to the line limbs, inte. li-

to the Wipers 11-12 of its individual By reason of the Wiper 29 being ed through normal contact 133, alterontact'l32, and thewinding of relay 127 to ground, the multiple contacts ot the tion to him that he Willbe unable to obtain :rupts the normal connection of said lino 'fnet 162 at contact 167, thereby allowing said selected called line are maintained inure condition to prevent the connection there With of another connector; The relay 149 is also soconstructed that the passage of ringing current from the generator 146. through the Winding 148 and condenser 159 will not move its contacts from their normal position. In addition to applying ringing current to the called line by the closure of its contact 141, the energization of relay 127 completes a circuitfor the control magnet 162, associated With the first selector D, over a'path extending-from the' live pole of the battery B through the heat coil H,'winding .of magnet 162, closed contact 163, contacts 164-85, closed contact 90, .Wiper 17, contact 20, link-circuit strand L Wiper 23, contact 26, alternate contact 118, link-circuitstrand .L, contacts 129, 165, closed'contact 166 and closed contact 167 of release relay RR 'to ground. The completion of this circuit energizes the control magnet 162 Which has its actuated parts so ,related to the switch contacts 79l01-'163.and -168' 82-lO2 that they are thrown totheir actuated positions. upon the deenergization of said magnet.

.As soon as the called party removes his. receiver 34 from its hook switch 35 in. re

sponse to the actuation of his call-bell 158,

he completes a conductive biidge between the line limbs S and P through his transmitter, and a circuit is therebycompleted from the live pole of the battery B through protective resistance 161, closedcontact 160,-

Wiper 29, contact 32, .line limb P, through 28, closed contact 145, winding 148 of relay 149 and interrupter 147 to ground. This circuit Will be completed as soon as the interrupter 147 or the interrupter and generator 146, grounds the winding 148. The flow of current over this path is sufii cient to cause the relay 149 to close its contacts,-

connecting the adjacent portions to the strands L""L at contacts 15l152. As

soon as relay 149 is actuated, transmission current for the called line issupplied overa circuit from the live pole of the battery 1 B winding of release relay RR, strand L wiper 28, contact31, lin'e limb S, switchhook 35, transmitter 36, closed contacts 37 38, line limb .1, contact 32., Wiper 29, normal contact 133, alternate contact.132,-winding of relay 127 to ground. Upon the completion of this circuit, the relay RR isenergized v i to break the circuit through the control mag magnet 162, upon its de'e'nergization, to move 7 the contacts 79-101-163 and 168.82102 to their actuated positions thereby againim.

100 the substation, line limb S, contact 31, Wiper I contact 163, co'nductively uniting the adjacent portions of the strands LL at centacts-79-101 and 82- 102 respectively," and interrupting the normal circuit through I the primary and secondary relays PRjand contacts 79 and 82 respectively.

As soonas the relay 162'is energized, a path for the supply of transmission current to the calling lineis provided. This path extends from the livepole of the battery B through *theupper windings normal contact 79, linlecircuit strand L, line' liinb P, through thehook-switch 35, transmitter 36,"clcsed contacts-37+38 "at the substation, line limb S, link-circuit strand L normal contact 82,-alternate contact- 81" ct rela 162 and the lOW8l,Wl11d1IlgS of re- 4 lays 17 O-1( 39 to ground The arrangement of the windings 011 169 is differential, and eonsequentlyat this time its contact 171 is not closed, Whereas the arrangement of the windings on relay 179 is cumulative and responds,

7 7-80 and close its contacts 172173.

said relay is energized to open its contacts The closure of these latter contactsprovides an additional path for transmission current'eX-' tending through the upper windings of renormal lays 16917 J,- closed contact 1.72, contact 174 of relay 175 to'link-circuit strand L, and thence upon return from united-,is dependent upon the response of the called party-it will be seen that a talkin circuit, which isthat ShOWIliH'hEElVY linesisnot completed until thecalled party At this time, it will be noted that cbntact 1G8 grounds the winding of relay 1715 thereby energizing the latter to move'its contacts 174-176 to their alternate positionst thereby reversing the direction of current flow to the called substation. This is occasioned for the purpose of operating pay-station and other devices which may be used at the substation. From the above it will be seen that talking circuit is thus established between the calling and called lines and that this circuit is conductively dividedand inductively united by the condensers 157-477 in the link-circuit strands v L L respectively.

7 It has' al't-eady been pointed out how the individual; switch mechanism would be restored to its'f -normal position in case all the link-circuits 'L.L were in use. If however, the calling party has obtained connecof relay 169 170, alternate contact-78 of relay 162,

tion with thedesired-called party, the occupied individual, selector and connector switches will be released at the end-of con- .'ersatiou in the following manner: As previously indicated, when the receiver ofeitherpart yis hung upon its switch-hook, both linednnbs S and P of the correspond h1g1 line are groundedat the substation. It

'Will also be remembered that during conversation,- the clrcultforsupplying trans-- mission current to'the calling station es:- tends from thelive pole of the battery B throughwthe upper windings of relays l69"-170'through th substation and back I through thelower a dings of said relays, tojground; Therefore, if it be assumed that the calling party first restores his receiver to its switch-hook, it will be observed that byprov-idinga ground at the-substation, the

lower windings of the relays 169- 170 will be'short circuited and the normal balance of the-windings of the relay 169 will be thereby destroyed and said'rela'y will close its con-V "tact 1'71." Thereupon; a circuitWillbe-completed through the release magnet RM"of the individual switch B and the release mag-'- net 'RM" bf the firstselector D which may be traced from ground at the release magnet Rh L througlf the Winding of said-magnet, normal contact 44, wiper 10, contact 13, closedcontact 171 of relay 169;Wi11ding oitherelease magnet RM to the live "pole of .the'ba'ttery B. On theother hand, it will be'remembered that a circuit for supplying transmission current to'the called line 'extends from the live pole of theybattery B through the'winding of release 'relay RR, .link-circuit-strand L line limb :3, through the substation and'back over thefline limb P, through contact 32, wiper29, normal contact 133. alternate contact 132, and'the winding of relay 12710 ground. Therefore if the called party first-restoreshis receiver to its hook, he will interrupt the circuit at his switch-hookv and thereby deenergizerelease I relay RR. Upon such deinergization, grounded contact 167 will be closed. The

closing of this contact will complete an additional'path to. groundfrom the upperiwind ings of relays-169170 which may be traced from said windings through closed contact 172, contact 176, link-circuit strand 13;"0011- tact '15,. wiper 12, line limb S, through the sub t Zion, line limb P, wiper 11, contact 1% strain s3, contact 26, a portion of strand L 2 cont: ts 1*291(l5, closed contact 166 and gro- The closing of this path of contact 167 again destroys the normal balance of the windings in relay 169 and 1 causes the'closure of its contact 171 with the consequent energization of release magnets RM and 'RM', as justpointed out.

Tne energization of release magnet RM closes a circuit from the live pole of bat-- wiper 17, contact 20, strand L turn completes a circuit from the live pole of the battery B through resistance 179, alternate contact 117, wiper, 22, contact 25, closed .contact 120, and winding of release magnet RM of the connector to ground.

v From this it will be seen that it is necessary to maintain the unbalanced circuit of the magnet 169 from the calling station until the release magnets RM, RM, RM and RM have attracted their armatures. The energization of release. magnet RM of the individual switch B closes its contacts 180 and 181, which are connected in bridge of the cut-off relay contacts 4142, and, as will appear more fully hereinafter, returns the release switch contacts, 4748- 49 to their normal positions, thereby completing a circuit from the live pole of the battery B through the winding of cut-ofi relay CO, contacts 51 52 and 47- 18 to ground. The cut-ofl relay CO is thus energized to break the circuit through contacts 1142, but the contacts 180-.-1-81 of the release magnet RM maintain the line limbs in circuit with the wipers 11-12, thereby maintaining the unbalancing circuit from the calling station for'the magnet 169. As soon as ground is removed at the calling station, the contacts of relay 169 are restored to normal, and

each of the release magnets RM, RM, RM and RM is de'elnergized. Upon the'deenergization of release magnetRM, wipers 10 11-12 are restored to their normal positions. In so doing, they pass over the multiple contacts of other link-circuits, but by reason of the disconnection of the wipers from the line limbs at both contacts tl42 of the cutoff relay CO; and contacts 180 181 of the release magnetRM, interference with conversation over any of these linkcircuits is prevented. As soon as the wipers reach their normal positions, the contacts -51-52 and 53 of the primary off-normal switch P0, are returned to their normalpositions and the circuit of the cut-off relay CO is thereby interrupted and the normal connection of the line with its wipers again established. At the first selector switch D, the energization of release magnet RM causes the restoration of the switch contacts 9596-97 to their normal positions, thus, energizing the private magnet 89 over a circuit extending from the live pole of the battery B, throu lrthe heat coil the winding of said magnet, contacts 96+95, and closed contact 9 1 to ground. The energization of the private magnet. disconnects the adjacent portions of the strandsL L and the wipers 17 and 18 at contacts 9091. Upon the deenergization of the reson of the mechanical relation of the parts,.

lease magnet RM, the contacts 79101- 163 and 16882-102, which were actuated upon the release of relay 162, are restored to their normal positions. .Upon the release of the release magnet RM, by reason of the mechanical construction to be herein after more fully pointed out, the wipers 16 1718 are restored to their normal positions.

During this restoring movement of the wipers, interference with conversations over strated, while upon the restoration of said wipers to their initial position, the contact 94 'of-the primary oif-normal switch PO is restored to the position illustrated, there- 'by interrupting the circuit of the private magnet 89 and allowing its contacts to return to normal. In a similar manner, wipers 22-28-24 of the second selector E are restored to normal. Thus, upon the energization of release magnet RM contact spring 108 of release switch RS is thrown to its cuit for the private relay 110, extending from the live pole of the battery B through Winding of said relay, normal contact 108,

alternate contact 107 to ground. The completion of this circuit energizes the, private '0 relay to disconnect wipers 232 1 at contacts 111112, but in order that the unbalancing circuit for relay 169 may be maintained until it is time to deenergize the various release magnets, the release magnet RM is provided with a contact 182 in bridge of contact 111 which is closed during the enefigization of release magnet RMH Upon e deenergization of release magnet, by reathe wipers 222324 are restored to their normal positions, the springs of the secondary off-normal switch S0 being returned to normal position during this restoring movement of the wipers, and the springs of the primary off-normal switch P0 being returned to normal at the end of such restoring movement. the latter interrupts the circuit of the private magnet and allows its contacts to assume their normal positions, WVhere the As before, the return of balance of the relay 169 is destroyed by the return of the called subscribers receiver to its hook, the unbalancing circuit is in-. terrupted at contact 166 of release magnet RM as soon as the energizing circuit is completed through said magnet by the action of the release magnet RM of the sec- I 0nd selector. 4

The mechanical construction of the con: nector switch is such that wipers 28'29- 30 are restored to their normal positions upon the deenergization of the release magnet RM. As previously pointed out, during connection there is a circuit from the live pole of the battery B through the cut-elf relay CO, contacts 5150, contact 32, wiper.

individual switclfB. The contacts of relay 127 also return to normal at this time, and thereby interrupt a circuit through the wind 154 of relay 1 l9 thus deenergizing said relay. t should be noted that if the above releasing operation takes place in response to the busy signal transmitted from interrupter 155 to the calling line, then upon' the movement of the wiper from the grounded contact, the circuit of relay 139 will be interrupted and the transmission. of the busy signal to the calling linethereby discontiued.

If'the calling party desires to restore the mechanism at the exchange to normal at any time prior to the completion of the connection with the called line, and after the selec tion of link-circuit LL the restoration of his receiver to its hook will simultaneously energize primary andsecondary relays PR and SR over circuits which have been previously traced, and which it will be remembered remain intact until connection isjestablished with the line of the called party. Upon the simultaneous energization of these relays, their contacts l8318 l will be moved into engagement and a circuit thereby completed from the live pole of the battery B through the heatv coil H, releases magnet Ptlvlflrelay contacts 183184:, contact 13,

wiper 10, normal contact l release magnet RM to ground." Upon the denergization of the release magnets RM and RM, both the first selector and the individual switch will be restored to normal, as previously inclicated, and as before, the release ofthis first selector D will occasion the release of the second sele'ctonE and the connector C,

case they be in circuit at the time.

By the use of the heat coil H and its associated parts, I am enabled to protect the circuits of an associated switch in case of undue flow of current therem. By the operation of the heat coil, the particular switch in which the trouble exists may be Ten-- 185 through which passes a rod 186 which is soldered in place by some readily fusible material. This rod controls contacts 187 1S81S9190191192. Upon the melting of the soldering material, due to the excessive heating of the winding of the heat coil, the rod 180 is moved to the right, due to the tension of-the associated spring contacts, and the contacts 191192 by separating open the conductor by which current is supplied to the switch from battery B. The engage:

ment of contacts 1S9190 grounds the, contacts 13 of the switch in trouble and thereby renders it busy to other switch mechanism; The engagement of contacts 187-488 completes a circuit for relay 193 which in turn, by its armature 19 i, completes acircuit for bell 19S and lamp 196, either or both of which may be used to indicate to attendants the trouble condition. This heat coil may be used in connection with the second selectors and connectors for like purposes.

Obviously in the practice of 'the system above outlined, the apparatus employed may be varied considerably in mechanical con-.

struction, and. I therefore do not wish to be limited to the specific forms of switch mechanism hereinafter described, but preferably I employ the mechanism illustrated in Figs. 2 to 11 inclusive.

Referring first to the individual switch B which is illustrated in Figs. 4 and 5, I preferably mount the bank contacts 131415,

ate frame 200 securely fastened to'a base 201 by bolts 202, the contacting ends of :the bank contacts are presented to the wipers 101112 in the arc of a circle and securely clamped in theframe 200 with suitable intervening insulation for rendering them electrically independent, while the wipers are mounted upon the shaft 203 journaled in the base 201 and in a bracket 20 1 carried thereby. The wipers are suitably insulated from each other, and are held in place upon the shaft by suitable clamping nuts. As clearly shown, the wiper 10, whichis a private wiper, is composed of two strips which are adapted to wipe over the middle row of passive contacts 13, while the outer wipers 11 and 12 -are composed of single strips adapted to engage the outer faces of the contacting ends of the strips 14 and 15 respectively. The wipers are given their rotary movement through the agency of a circular ratchet 20b mounted on the shaft 203.. The ratchet is adapted to be engaged by'a driving pawl 206 carried upon the armature 207 by the motormagnet M. A spring 208 tends to force the driving pawl 206 into engagement with the ratchet teeth. Upon eachenergization of the motor magnet M, the pawl 206 engages a tooth of the ratchet 20.5 and moves it and the wipers one step. Its ad- Vancemovement is limited by itsengagenient 'with the bracket 204. The armature "a rend 210 of the. armature 207. r The contact interrupted upon each energization of the magnet M, andthese contact springs are illcluded in a circuit of the motor magnet, as previously described. Theratchet 205 is retained in its various positions by retaining pawl 211 mounted upon the base 201 and pressed into its engaging position by a spring 212. The contacts 50515253 of the primary off-normal switch PO are suitably secured to the base 201, and by reason of their inherent tension, normally occupy the position illustrated, but are adapted to be moved from such position by the insulated projectionf213 carried by the ratchet 205. This movement from normal occurs upon the first rotary step of the ratchet.

The base-201 also carries the release magnet RM and contacts 180181 and contacts 474849 of the release switch RS actuated thereby. Normally the contacts 474849 are held in the position illustrated, through the pressure of the spring arm 214, carried by the armature 215 of the release magnet. The inherent tension of this spring is such thatupon the movement 9f the spring. arm 214 to theleft, spring.47 will disengage spring 48 and engage spring 49.

Upon the first. movement of the armature 207 of the motor magnet M, the spring arm 214 is moved in this direction by reason. of

an engaging projection 216 carried by the.-

armature 207. As soon as this takes place, the retaining pawl 211 has its tail freed from a projecting shoulder 217, carried on the spring arm 214, and through the tension of the spring 212, is moved into engaging po sition. By reason of the angular end on the tail of the pawl engaging the outer or right,- hand face of the projection 217 on the spring arm 214, after this first actuation of the motor magnet M, the arm 214 is prevented-from forcing spring contact 47 out of engagement with spring 49 and into engagement with spring 48. In the operation of the mechanism upon the subsequent energization of the. release magnet RM, the. attraction of its armature 215 causes the projecting shoulder 217 on the arm 215 to pass beyond the angular projection on the tail of the retaining pawl 211, and to engage its upper side whereby, upon the retraction of the armature 215, the pawl 211 is again moved to the non-engaging position, as illustrated. While the release magnet RM remains energized, the contact springs 18018l are moved to. their engaging positions. These springs-also serve to retract the armature upon a the deenergization of the magnet. Upon the removal of the retaining pawl 211,

65. thawipers 1011 and 12 are free to return s 'r i1i? s-4546 normall in engagement, are

P e y also carriesfiXed contacts 19-2021 which are arranged in a bank 220 with their. free ends adapted for the attachment of suitable conductors, and have their contacting inner ends terminating in a spherical surface. These contacts are suitably insulated from each other and. coiiperate with the wipers 161718 which are pivoted at the center of rotation of the spherical surface to the lower end of a-rotary shaft 221, carried by the frame 219.; The wipers'are rotatable with the shaft 221 in a horizontal direction, and in addition, may be rotated vertically about a pivot 222 through the agency of an additional longitudinally movable shaft 223, having a broad foot 224 which engages a rearward projection 225 on .the wipers. Thus, by rotating the shaft 221, the wipersmay be given their primary movement to *the desired group of bank contacts, and by subsequently giving the shaft 223 a longitudinal movement, the wipers may be moved to the desired bank contact in the selected group. The foot 224 on the shaft 223 is made sufiicientlylarge to engage the projection 225, no matter what the position of the wipers may be. The mechanism associated with the primary magnet PM, by which the shaft 221 is given its primary or rotary movement, comprises an actuating pawl 226, carried by the armature 227, adapted to engage the teeth of the ratchet wheel 228, to step the shaft around. The advance movement of the pawl 226 is limited by the beveled'stop 229. The armature 227 is retracted upon the denergization'of the magnet, by a suitable spring 227 which engages the angular end of the armature. The shaft 221 is retained in its various positions by the retaining pawl 230 which is adapted to engage the teeth of the ratchetwheel. The upper end' of the. shaft 221 carries a member 222, as illustrated in Fig. 3, having a projection 223 which normally maintains the spring contact 94 of the primary off-normal switch P0 in its open position. but which, upon the first movement of the shaft, allows it to close under its inherent tension. The secondary magnet SM,

through the agency of its armature 231, actuating pawl 232 and the ratchet teeth 233 on the shaft-223, steps the latter downward to carry the contactingends of the wipers 161718 into their desired positions. A suitable retaining pawl 234 engages the teeth 235 on the shaft 223 to hold it in its diiferentoperating positions. The shaft 223 is also provided with a suitable spline 236, which, after the first movement of the shaft, engages a tooth of the ratchet wheel 228 to lock the shaft 221 against rotation. Contact prings St88 of the secondary off-normal switch are normally held against their spring tension in the position illustrated in Fig. 1 through the agency of a projection 237 carried. at the upper end of the shaft The outer end of this projection normally en' gages a pin to hold the contacts in this position. The vibratory circuit of the secondary magnet SM is completed through the contacts 98 99 which are actuated by the armature 231' of said magnet. Upon the energization of the release magnet as previously'pointed out, contact 83 is opened, contact 100 is moved to its alternate position' and the contact spring 95 is restored to its normal position, that is, brought into en' gagement with contact spring 96; the armature 239 of release magnet Rh" directly engages the contact springs 100 and 83 to give them the desired movement and it is provided at its lower end with a member 240 which extends beyond the contact spring 95 into'a position to draw it to its normal position upon the attraction of the armature 235% This spring has a tendency to move to its alternate position. but is normally held against such movement by the catch 24:1

pivoted at 242 to a post projecting from the rame 219. T he catch 2 i1is moved from its retaining position. so as to allow the spring 95 to move to its alternate position, upon the first energization of the primary magnet PM. This brought about through the agency of a lever pivotally supported near its center upon the frame 219 and having one end lying in. the path of movement of the armature 227 of the primary magnet PM. Its opposite end is provided with an upturned projection 24%- which bears against the under side of the catch lever 2&1. Upon the first movement of the armature 227, the Lever 2123 is rocked about its pivot and its upturned end rides over the inclined surface 2.15 on the under side of the lever 2.41 so as to rock the latter on its pivot 242 and thereby releases the spring 95 and allows it to move to its alternate position.

s previously indicated, after the wipers have been given their primary and secondary movements, they are retained in their connected position by means of the primary retaining pawl 230 and secondary retaining pawl in giving the wipers their primary movement, the shaft 221 is rotated against the tension of a spiral spring 246 contained in a suitable casing carried by the frame 219. Similarly.- in giving the wipers their secondary movement, they are {rotated against the tension of a spiral spring 248'located about the pivot-.222 and coiiperating between the lower end of the shaft and said: wipers. ln-vievv'ot' this, it is only necessary in order to return the wipers and their switch parts to their normal positions,

time, and thereforemroves them out of engag ing position. This will be more apparent from j inspection of Figs. 2 and 8 In which it will} be seen the prim ry retaining pawl-230 1s provided with a tail having an upturned end 2%? which is adapted to pass through a cooperating opening 248 in the member 2%0. Similarly. the secondary retaining pawl 234 is provided with a tail having a similar upturned'end 2&9. similarly adapted to pass into an opening 950 in the member 240. Upon the attraction of the release magnet armature 239, the member 240 passes over the upturned ends 2-H and 2-19 until the openings 24tS-250 come into registration therewith. The member 2-1 0 then. by the action of the spring 251. moves downward far enough to engage the projecting; ends of the pawls: then upon the retraction or" the armature 239 these pawls are mo ed out of engaging position and. through the agency of the springs 2e.6 248. the wipers are returned to their normal positions. For convenience in establishing connection between the various switch terminals and the incoming leads, connecting strips 2522F-3 are carried by a suitably insulating frame 219 of the switch. v

As obviously indicated. certain contacts are thrown to their abnormalpositions upon the deenergization of relay 162 and subsequently returned to their normal positions upon the de'c ncrgizati on of release magnet RM. The contacts so actuated are desianated 79101163-1GS92-102. The mechanical arrangement oi the narts by which this in vement is accomplished. is clearly illustrated in Fig. S. The contacts 79101-16316882-102 are suitably carried upon, and insulated from. the main frame 219 by means of a supporting bracket 251-. and their free ends lie in proximity to one end of the magnet 162. They are forced from their normal positions by the insulatinn" spacers carried a the upper ends of lever'257. pivoted intermediate of its length to the magnet frame.

In operation. as soon as the force by which the lever 257 is moved. is withdrawn. the tension of the springs engaging the spacers 25 256 forces the upper end oi the lever 57 toward the right into the position illus;

rated. uiereby allowing the springs to assume their normal positions. i'ne armature 258 of the magnet 162 carries a spring pressed arm 259v which is provlded with a catch 260 at its outer. end, adapted to engage the lower end of the lever 257. Normally thc.catch lies in non-engaging position, but

. upon the attraction of the armature 258, the

arm 259 is moved far enough to allow the,

catch 260 to engage the lever and upon the retraction of the armature the lever is rocked. about its pivot so as to force the spacers 255-256 against the pressure of the -co'ac'ting contact springs and thereby move the latter. to their abnormal positions. Co-

operating Withthe arm is a member 261 .carried'hy the armature 239 of the release magnetRM and acted upon by the spring 262; This member normally rests in engagernent with the stop 263. WVith the spring contacts '79101163 and 16882102 in their abnormal positions, theend of the arm 259 adjacentito the armature'258 will engagethe side of the member 261. With the parts in'this positiom'u'pon the attraction of the armature 23 9 ofthe release magnet,

ymember 261 will be'moved downward past thereupon return to its normal position, thereby permitting the springs also-to return :the endof. the arm 259 so'as to engagethe underside of its adjacent end. Then-upon the retraction of the armature 239, the mem-- her 261 will rockthearm 259 about its pivot. and'tlrereby releasethe lever 257 which will "to their'normal positions.

The second selector'E is. substantially the same'inconstruction as'thafirst selector D just described, but as will 'be apparent, the primarymagnet PM, secondary magnet SM, release-magnet RM will be replaced bywthe magnets PM, SM and RM of the second selector. while'the release'springs 9596 97 of the first selector will be replaced by the contact spring 108 and its cooperating contact springs. primary oil-normal switch PO and contacts 847 88 ofthe secondary off-normal switch S0 of the first selector D, will be replaced by. contacts 106-107 of the primary olfnormal switch P0 and contacts104-109 of the secondary oil-normal switch S0 of the'second selector E; andin the second selector, the relay 162 with its associated parts will be omitted. The connector. C also partakes of the general construction of the first selector heretofore described in detail.

Referring to Figs. 9 to'11 inclusive which illustrate aconnector, it will be seen that the operates through'the agency of a member tacts 118-121.

I energization of release magnet llM tension of the spring 132 and its coiiperating' Likewise, contact 94 of the,

2 10 to release the primary and secondary.

retaining pawls in a manner similar to that heretofore described but the catch lever 241 of the selectors is omitted and the upturned end 244 of the lever cooperating with the primary magnet armature 227 engages directly with the inclined surface 263 formed on the member 240'. In the case of the connector, the projection 222 at the upper end of the primary shaft 221 controls the move ment of the single contact 120 of the primaiy oil-normal switch P0 while the projecti on 237 at the upper end of theseconda-ry shaft 223 controls the movement of the concontact 118 moves to its alternate position upon the first downward step of the shaft 223, while the contact 121 moves from its normal position upon the first downward step of said shaft, but does not move to its alternate'position until said shaft has taken As previously indicated,

a'second step. {This is brought about ivy properly. spacing the spring conta cts 118 121 .and' theircoiiperating contact springs, as-

illustrated, in Fig. 9. Likewise, in the connector, contact spring 132 and its cooper-at ing contacts are under the joint control of release magnet RM and magnet 125. previously indicated, contact 132 is moved to'its alternate position upon the doiinervgization of relay 125 and is againrestored to its normal position upon the subserpient The springs is such that they normally occupy this position illustrzlzged. This movement of r the Contact is bro ght about through the agency of an arm 261 carried by the lower end of armature 265 of the relay 125 and having its outer end forced upward by the spring 266. Upon the attraction of the armature 265, aprojection 267 on the arm 264 passes to the left of an insulating block 268 carried by the spring 132, and upon the retraction. of the armature 265, the right hand shoulder of the projection 267, by engaging the left face of the block 268, forces the spring 132 against its inherent tension to its alternate position. In order to release the parts. the armature 269 of the release whose outer end 271 overhangs the outer end of the arm 26% so that upon the attraction of the armature 269, the outer curl of the arm 264 is drawn downward so as to free the projection267 from theblock to allow thereturn of the spring 132 to its normal position. ciated with itpsuitable contact springs arranged so that when the armature is attracted the spring Contact 131 is closed.

Similarly. the release magnet llM has assomagnet FM is provided'with an arm 270 The-relay has associated with it suitable spring contacts co-- operating with the armature 269, so that upon its. attraction, contacts 11912 l66 are opened. Obviously, the frame of the connector may carry any of the other associated relays such as the ringing relay 142. As previously indicated, the wipers of the connector are placed two steps distant from Obviously in carrying out the invention 7 many alterations and modifications may be made in the mechanical construction of the switch mechanism herein disclosed, as well as many alterations and modifications in cir-' cuit connections, without departing from the spirit and scope of the invention. In the diagram of Fig. 1, I have illustrated a plurality of batteries whereas it shouldbe undeistood that these may be replaced by a single battery, as would ordinarily be the case in actual practice. I therefore, do not wish to be limited to the exact matter disclosed, but aim to cover by the terms of the appended claims all such alterations and modifications.

Vhat I claim as new and desire to secure by Letters Patent of the United States, is:

1. A telephone exchange system comprising a subscriberstelephone line, an active switch contact in which said subscribers from said passive contacts, means responsive to removal of the receiver at the calling substation for causing said active contact to automatically select and stop in engagement with the passive contact of an idle one of said link-circuits, and means for sending a characteristic signal over said subscribers telephone line in case all of said link-circuits are in use.

2. A telephone exchange system comprising a subscribers telephone line, an active switch contact in which said subscribers line terminates. coi ieratin assive conl s tacts adapted to be engaged by said active the subscriber may then restore said active contact to normal.

3. A telephone exchange system comprising a subscriberis telephone line. an active contact in which said subscribers line terminates, cooperating passive contacts adapted'to be engaged by said active contact, electrically operated signal transmitting apparatus associated with the last of said passive contacts to be enga ed, a plurality of link-circuits extending from the remaining passive contacts, means responsiue to removal of the receiver at the calling substation for causing said active contact to. pass over said passive contacts, means for arresting said movement in case an idle passive contact is encountered, means for operating said signal transmitting apparatus in case its passive contact is engaged by said active contact and signal receiving means associated with said telephone line.

4. A telephone exchange system comprising a subscribers telephone line, a plurality of associated link-circuits, interconnecting switch mechanism comprising an active contact, cooperating passive contacts adapted to be engaged by said active contact, means responsive to removal of the receiver at the calling substation for causing said active contact to pass over said passive contacts and means for arresting said movement in case an idle passive contact is encountered, electrically operated signaling apparatus associated with the last of said passive 0on 'tacts, and means for operating said signal? mg means as soon as its passive contact engaged by said active contact. 1

5. A telephone exchangesystem c'omprising a subscribcrs telephone line, a plurality of link-circuits extending therefrom, automatic switching means for establishing con;-

nection between said line and an idle one of said link-circuits, means for restoring said switching means to normal positi0n,-and means for placingsaid restoring means under the control of the subscriber in cas all of said link-circuits are in use. I

6. A telephone exchange system comprising a subscribers telephone line, a plurality of link-circuits, electrically controlled switching means for automatically establishing a connection between said line and the first encountered idle one of said linkcircuits, means for restoring said switching means to normal position, and means'for placing said restoring means under the control of the subscriber in case all the encoun' tered linlocircuits are in use.

7. A telephone exchange system comprising a plurality of subscribers telephone lines, multiple interconnecting linlccircuits,

automatic switching means for selecting an idle one of said link-circuits and completing connection therethroughbetween a calling lineand a calledline, means for restoring said switching means to normal position.

and means for placing said restoring means under the control of the subscriber in case all of said multiple link-circuits are in use.

8. A. telephone exchange system comprising a subscriber's telephone line, a plural-

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