US1469807A - Automatic telephone system - Google Patents

Description

R. G. RICHARDSON AUTOMATIC TELEPHONE SYSTEM Oct.. 9 1923. 1,469,807

' A lavez-ZID? EUC/Pneu lcit. 9 1923.

R. G. RICHARDSON -AuoMATIc TELEPHONE `SYSTEM 3 Sheets-Sl-wot 2 FiledA Jan. 8 191'? tuant-:P

R. G. RICHARDSON' AUTOMATIC TELEPHONE SYSTEM 1917 3 Sheetsv-Shblat 3 Filed Jan. 8

m mmm mm m, m En, m N l BODNEY UTMATIC TELEPHONE SYST elle.

lneon, or cmcnco, unimore, assrenoa 'ro auroarrc nnnlcrarc Y, or cnrcnec, rumors, a coarona'rrcn or rLLors.

application ale'd January E, 1917'. Serial No. 141,130.

To all 'whom zt may concer/h.'

Be it known that l RODNEY G. RICHARD- soN, a citizen of the nited States of America, and a resident of Chicago, county of Cook, and State of illinois, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a specification.

My invention relates in general to automatic telephone systems of the usual percentage type in which automatic switching apparatus is provided at the exchange, through the medium of which calling subscribers are enabled to obtain desired connections; and embodies a number of features which will be pointed out and described hereinafter.

One of lthe principal features of my invention relates to an lmproved trunking system whereby subscribers are enabled to call an operator for the purpose of placing a long distance call, or for other purposes.

In' a well known type of automatic system employing individual line switches, first selector, second selector, and connector switches, it has been customary in the past to assim a certain level, for example, the tenth level, of the rst selectors to the trunks extending to recording toll operators. With this arrangement when a subscriber desires to place a long distance call he will remove his receiver and then proceed to manipulate his calling device in accordance with the digit 0, thereby operating a -first selector to extend vconnection to a recording operator. While this method of operation is fairly simple for the subscriber,

it has the great disadvantage of reducing the capacity ofthe exchange by 1000 lines, which is often such a serious objection as to warrant extraordinary edortsto overcome In myv improved trunkin system, the groups of trunk lines exten ing from'the individual line switches to the irst selectors r are combined into main groups of line terminating in an idle first selector. If

a connection to another subscriber is desired, the calling subscriber then operates his calling device as usual to obtainthe lconnection and it is to be noted here 'that all thelevels of the .first selector are 'assigned to main groups of subscribers lines, none of them v being reserved for the toll recording trunks'.

Suppose, however, that the calling subscriber esires to obtain connection with a toll recording operator. In this case he has simply to press a button with which his substation instrument is lprovided as a result of which operation any idle fin er switch is set in motion-to find the trunk line to which the calling subscribers line is connected and extend it to an operators position.

Another' important feature of my invention relates to the finder switches and has for its object thesecuring rapidity in extending connections. lt has been mentioned before that each main'group ci trunk lines which is accessible to a given group of linders isvmade up of a number of smaller or sub-groups. The finder switches employed are preferably of the type which have primary movement to select groups (sub-groups in this case and secondary movement to select the individual trunk line vin the group.` By my invention, however,

the finder switches have no normal position as regards the groups and when disconneccuit is provided whereby a calling sub-- scriber will start the finder switch which at the time happens to be'associated with the group of lines ot which his line is one, thereby permitting the primary movement of the switch to be eliminated; or in case there is at that time no finder switch associated with his group, that finder will be started which is at the time associated with the of extreme v next group in reverse order, etc. ln other words when a calling subscriber resses his button to call an operator, he wil start that finder switch which requires the least movement to locate the group; and if there is already a finder associated with that group,

that finder will be used, and no primary or group selecting movement thereof is required.

05 I. tending to the selector switch E. The selec- 'llhe foregoing/and other useful objects net now specifically mentioned are attained ment H, in a system embodying the -principles of my invention. The connection hasv been established through the mediumjof the individual line switch C (Fie. 1) and the finder switch (Fig. 2). In F ig. 3 I have shown the starting circuit extending through three finder switches of the same group;

while Figs. 4 and 5 are views4 of a special bank with which each finder switch is provided.

` The substation A (Fig. 1)l may be of any approved automatic type, such` for example, as the substation shown in British patent to Martin, No. 1419 of 1910. As represented herein, it comprises essentially the receiver 2, transmitter 3, switch hook 4, ringer 5, and condenser 6. The resistance 10, in series with one of the line conductors, is normally short-circuited by the springs of the push but-ton 11. Being an automatic substation, there is also provided a. pair of impulse springs 7 and 8 controlled by an impulse wheel 9 through the medium'l of a finger hole dial (not shown).

The line conductors 12 and 13 of the substation A are connected at the exchange tov the individual line switch C which is of the eneral type of line switch disclosed in the ritish patent to James, No. 26,301 of 1906; being, however, of the particular type shown in U. S. Letters Patent No. 1,078,690, granted Jan. 17, 1912, to Frank Newforth. Through the medium of line switch C the line-of' substation A when calling is given access to a plurality of trunk lines extending to selector switches.

rlhe line switch C and a plurality of similar line switchesv are controlled in their trunk selecting operations by means of a master switch. D. rlhe master switch D is of the general type of master switch disclosed in the above mentioned British patent to J ames, No. 26.301 of' 1906; being, however, more nearly of the particular type disclosed in the British patent to Martin, No. 1419 of 1910, also previously referred to. Asis well known, the function of the mas-l ter switch is to maintain the plungers of all idle line switches which it controls in position before the terminals of an idle trunk line.

One of the trunk lines to which the line switch 'C has access is shown in Fig. 1 exacceso? is'to be extended to an operators position,

as will be explained fully hereinafter. e

The finder switch F. (Fig. 2) is in general imilar in construct-ion to the switch shown in'U. S. Letters Patent No. 815,176, granted March 13, 1906, to Keith.,- Erickson, and Erickson, except that the side switch and private magnet are omitted, and the circuits are changed radically in order to permit the switch to erform the functions of a finder switch. t is thought leestv to de.-` fer the description of the circuits until later, when the operation of the complete system will be considered in detail.

There are, however, `a number of important differences in'mechan cal construction which it is considered advi able to explain briefly at this time. The Ix ith and Erickson switch above mentionedhas a bank of 100 sets of contacts, each set comprising two line contacts and one private contact, ar-

ranged in ten groups or levels. The switchv with a private or test wiper, which is the wiper 121. The finder switch bank also has 100 sets of contacts divided into ten levels (one set in each of the three lower levels being shown in the drawing) and the wipers 121,122, and 123 have a vertical group selecting movement under control of the vertical The magnet 114, and a rotary movement under A control of the rotary magnet 115. So far the finder switch F is substantially like the switch shown in the Keith and Erickson patent. An essential difference appears, however, in the release mechanism.

ll provide separate holding pawls for the switch shaft for controlling its restoration in a rotary direction vand in a vertical direction. These pawls are normally in engagement with the ratchet teethof the shaft and may be of any well known construction. When the rotary release magnet 117 is energized the rotary holding pawl iswithdrawn to permit the release of the shaft as regards its rotary movement and when the vertical release magnet 116 is energized the vertical holding'pawl is withdrawn Vto permit the release. of the switch shaft vertiare permitted to close on the first rot-ary step, and the vertical off-normal springs 119 and 120, which are controlled by the shaft cams 131 and 132 and the do 133. When the shaft is in its lowest positlon the spring 119 is disengaged from spring 120 by the cam 131. When the shaft is stepped up in the operation of the switch, the spring 119 is held in the position shown in Fig. 2 by the dog 133 until the shaft arrives opposite the tenth level, whereupon the cam 132 disengages the dog 133 and permits the springs to close. v

-In addition to the foregoing details, -each finder switch is also provided with a vertical strip of ten group test contacts and a vertical strip of ten starting circuit contact sets. These test and starting circuit contacts are preferably combined in a single bank as shown in Figs. 4 and 5, andmay be mounted in any suitable manner on the switch frame. The vertical test wiper 124 is alwaysl in engagement with some one of the vertical test contacts 134, 135, etc.; and is attached to the member 2,02 which in turn is rotatably mounted on an upward extension of the switch shaft 200, and is held in position by the adjustable collar 203. When the switch is idle the starting wiper or contact member 125 is likewise in engagementy with some one of the contact springs 129, 126, etc., of the starting circuit contact sets. When the finder switch is engaged in a connection, however, the starting wiper 125 is disengaged by means of the magnet 113. The magnet 113 is rigidly mounted on the switch shaft which forms its core, and is provided with a U shaped armature 204 which is rotatable to a limited extent on the shaft. The upper leg 208 of the armature 204 is preferably of brass to avoid short-circuiting of the magnetic circuit. vWith no current flowing in the Winding of magnet 113. the armature 204 is held by the spring 206 in such position that the wiper 125 engages the contact spring 129 (or 'corresponding spring in another level), and the spring 206 has sufficient tension to cause the-spring 129 to be separated from its resting contact. lVhen the magnet 113 is energized, the armature 204 is rotated several degrees and the starting wiper 125 is thereby disengaged from the contact spring of the starting circuit contact set opposite which it is standing and the springs of such set are permitted to close.

With each of the ten sub-groups of trunk vwinding 142 of the rela lines to .which .the finder switch F has access there is associated a set of three group relays which among other things contr'ol the removal of the test 'potential from-the finder switch group test contacts. Thus, referring to Fig. 1, the first group of trunk lines, not shown in the drawin but which are understood to b e multipfed in the iirst levels of the group of finder switches of which the finder switch F is one, are provided with the group relays 136, 137, and l138; lwhile the second group of trunk lines, which is'similarly multipled in the second level of the finder switches, and which includes 4the trunk line terminating in'the selector E, is provided with the group relays 139,l 140,'and 141. It is understood that each of the other elght groups of trunk lines to which the group of finder switches has access is similarly provided with a set of group relays. The relay 136, when energized, removes ground potential from the group test contact 134 and its multiples in the banks of the other finder switches of the group, and

the corresponding relays in the other sets' of group relays perform like functions.

Vith each set of group relays there is associated a starting wire. Considering the second ciated set of group relays, the starting Wire 244 is multipled at one end to all the first selectors in which the trunklines terminate, including the selector E; it includes the 139; and it termi-- nates in spring 126 o the second set of. starting circuit contacts of the finder switch F, which it should be mentioned is'assumed to be the first finder switch' of the group. In the same way each of the other groups of trunk lines has a starting wire' which extends by Way of the associated group relay corresponding to relay 139 to the starting circuit contact bank in the lirst finder switch; and since there are. ten groups of trunk lines there will be ten of these starting Wires. The starting Wires are not multipled in the other finder switches of the group directly, as are the vertical and rotary test contacts and the line contacts, but are tapped onto a continuous series or loop circuit eX- tending thro-ugh all the finders and which can be best understood by reference to Fig. 3.

In Fig. 3 there is shown the wiring of the starting circuit cont-act banks of three finder switches, this number being thofught suiiicient for purposes of illustration. Beginning with t-he starting Wire 044 which is associated with the tenth group of trunk lines, the circuit may be traced by way of the top or tenth sets of starting circuit contact springs group of trunk lines and the asso? of the three finder switches in series and conductor 300 to the starting wire 944 of the ninth group, thence by way of the ninth sets the finder switch F. Briefly stated, the starting wiper of each idle finder switch opens the starting loop and is in electrical connection with the upwardly extending portion thereof.

In addition to the tenf sets of group relays, there is provided a pair of relays 150 and 151, which are 4common to these up relays, or in other words, which are in ividf ual to the group of finder switches whichincludes the finder switch F. The relay 150 is a general alarm relay, while rela-y 151 controls the ground connection to the common conductor 152. This latter conductor, it may be mentioned, is multipled to the irst selectors of all the ten groups'of t-runk lines which are served by the finder switch F andA associated finders. p

The operators equipment, which has been indicated in Fig. 2 by the reference character H, comprises -a group of relays, the signal lamps L and L and a key K. The utility and o eration of this apparatus will be described ater.

1 have shown throughout the drawings a plurality of batteries, lbut it is to be understood that in accordance with the usual prac tice there may be and is preferably but one battery, the positive pole of which is grounded.

Having described more or less briefly the apparatus involved, l will now proceed to explain the operation of my improved telephone system. In order to afford an opportunity of describing the operation of the selector E, it will first be assumed that the subscriber at substation A desires to obtain connection with another subscriber, after which the assumption will be made that the same subscriber desires to communicate with the operator Ipresiding over the operators equipment this latter being the complete circuit connection shown in thedrawings and previously referred to.

Referring to Fig. 1, when the subscriber at substation A removes his 'receiver to initiate the call, an energizing circuit is completed over the line conductors 12 and 13 for the line relay 16 of the line switch C.

Upon attracting its armature,- the line relay the bank springs 30-33, inclusive, into en-V gagement, respectively, with contacts 34-37,

inaeaeor inclusive; and the latter disconnecting the line conductors 12 4and 13, respectively from ground and from the line relay 16. y the engagement of bank 4springs 80 and '33', respectively, with contacts 34 and 37, the line conductors 12 and 13 are extended, respec-v tively, to the low resistance relay and the l1ne relay 50 of the selector E, it being noted that the conductor 12 passes also through the lower' winding of the line relay 50.

The relays and 40 are accordingly energized 'over the loop circuit including substation A and the line relay 50, upon attracting its arma-ture, closes a circuit for the slow-acting release relay 51. Upon energizing in turn, the relay 51 completes a holding circuit for the line switch C which may be traced as follows: und at GT, contact 63', armature 64, con uctor' 38, contact 35, bank spring 31, and holding windlng 18`to battery Since the line relay 16 is slow acting, it retains its armature to maintain the pull-in winding 17 energized until after the above holding circuit has been established. A branch of the holding circuit extends .by way of conductor 19 to multiple test contacts in the banks of connector switches having access to the line of substation A, where by a ground poten-tial on these test contacts the said line is made busy. By the engagement of bank spring 32 with contact 36 the master switch D is operated in well known ina-nner to advance the plungers of all the remaining idle line switches into position before the terminal of the next idle trunk line.

rllhe foregoing operations have occurred in response to, the removal of the receiver at substation A. It has been assumedthat the calling subscriber desires to connect with another subscriber in the exchange and he will therefore lproceed to operate his calling device in accordance with the irst digit in the desired number. By the operation of the calling device, a series of interruptions is produced in the line circuit which as just explained now includes the line relay 50 and the relay 40 of the selector E in series. At each interruption of its circuit, the line relay 50 deenergizes momentarily and ksends an impulse from ground G6 throu h the slow acting relay 52 and the vertica -magnet 53 in series. Responsive to these impulses the vertical magnet operates to raise the switch shaft step by step until the wipers 70, 71, and 72 arrive at that horizontal level of' bank contacts in which are located trunk lines extending to the desired main group of subscribers lines. y At the first interruption of the line circuit the relay 40 deenergizes also and by closing the back contact of armature 41 short circuits its winding so that it is excluded from the line circuit` during subsequent impulses. Since the llll vto prevent the closure o relay 40 does not again energize after the first interruption of the line circuit, the off-normal contact springs 44 are provided the finder switch starting circuit. The off-normal springs 44 are permitted to 'separate on the first upward movement of the switch shaft,v The slow lacting relay 52, which as pre1 viously'mentioned is included in the vertical magnet circuit, .is energized at lthe first impulse and retains its armature attracted vduring the vertical movement of the switch. Upon the first upward movement of the switch shaft the off-normal springs 58 are closed, thereby completing an initial energizing circuit for relay 55 which may be traced as follows: ground at G7, the Working contacts of amature 64, the armature of relay 52 and its working contact, the said off-normal springs 58, and the winding of relay 55 to battery Ba.- Upon energizing, rel-ay 55 prepares at its lower armature a circuit for the rotary magnet 54, which is held open during the vertical movement of the switch by the relay 52, and at its up per. armature locks itself independent of the relay 52 by closingl the following circuit:

rounded conductor 38, lower armature of t e rotary magnet 54 and its resting contact, upper armature of -relfay 55 and its working contact, junction point 80, off-normal springs 58, and the winding of relay 55 to battery B".` At this point it'should be mentioned that bv the closure of the off-normal springs 58 the line switching relay 63 was connected in series with relay 55. But since the junction point 80 has already been connected to ground as just described, it will be seen that the switching relay 63 is short `circuite for the present and remains temporarily inoperative.

lVhen the slow acting relay 52 deenergizes at the end of the series of impulses it completes at its back Contact Vthe previously mentioned circuit of the rotary magnet 54, extending from ground G7, ovei` an obvious path. Upon energizing, the rotary magnet operates to rotate the Wipers 7 0, 71, and 72 into engagement withjthe first set .of bank' contacts of the horizontal `level opposite which they were raised. Near theend of its stroke the rotary magnet also breaks. at its lower armature, the locking circuit of relay 55; and at its upper armature the vcircuit-connecting the line switching relay63 with the junction point 80. Upon deenergizing, the relay`55 breaks the energizing circuit of the rotary magnet which accordingly retracts its armatures to again close the contacts controlled thereby. The operation now depends on whether the first trunk line, the terminals of which are now engaged' by the selector wipers. is busy or not. Assuming that this trunk line is busy, the test contact upon which the test or private wiper 71 is resting will have ground potential vuponv iti-which .ground potential will serve to maintain the switching relay 63 short-circuited and also to again energize the relay v55. The rotarv magnet circuit is therefore again closed. and the same operation is repeated. A It willbe seen then that the relay 55 will operate as an impulse sender to step the switch wipers around through the medium of thel rotary magnet as long as the test wiper 71 continues to engage busy or grounded test contacts. When a non-bus provide against the deenergization of rela s 50 and 51; shifts the private wiper to t e grounded terminal of switching relay 63; and disconnects the line conductors from the line relay,50 and extends them by way of theline wipers and 72, and the line conductors of the selected trunk to the line relay of the second numerical switch of the series, which may be a second selector switch similar to thel selector E. The line relay of the second selector is accordingly energized over the line circuit and through the medium of the usual slow acting release relay connects ground to the third conductor of the selected trunk` thereby establishing a new holding circuit for the line switch C and the switching relay 63 which includes the private wiper 71 andthe upper armature of relay 63 and its working contact. It is understood, of course, this new holding circuit is completed' before the slow acting release relay 51 has had time to deenergize.

Having operated the first selector E in the manner above explained, the calling subscriber may now manipulate the dial of his calling device in accordance with the remaining digits in the number, whereby the second selector and the final connector switch are lcontrolled in the usual and well known manner to extend the connection to the desired subscribers'line. The foregoing operations,

together with the signalling of the called sub-- scriber and the final disconnection of the switches after conversation are the usual ones station A in extending a connection to an operator. Since the preliminary operations responsive to the removal of the receiver or ungrounded contact is reached and t e rotary magnet are the same, it will be assumed that the subscriber has removed his receiver, that the 50, 40, and 5'1 ofthe selector are inenergized'v lineswitch C has operated .to extendconnection to the selector E, and that the relays `relay 50 is not'v aected by vthe decreased current flow in the line circuit and maintains its armatures attracted. `Relay '40, however, is mar inal and at once retracts its armature, there y short-circuitlng ltself at the back contact of armature 41 so that it` will not again be energized when the push button at the calling substation is released. As a further result of the deenergization of relay a-starting circuit for initiating the operation of fan idle finder switch is closed over the following path: ground at G2, resting contact of armature 153 and the said armature, common conductor 152, off-nor-f mal s rings 44 of the selector E (now closed amature 43 and its working-contact, armature 42 and its resting contact, windin 84 of relay 82, armature 87 and its restl contact, starting wire 244 including the w1nding 142 of relay 139, the Second set of starting, circuit contact springs 126 and 127 of finder switch F, conductor 128 including in series the second set of starting circuit contact springs in' each of the other finders of the group (it being assumed that no finderhas its wipers standing opposite the second level, see Big. 3), starting circuit oontact spring 129 of the first set, starting Wiper 125 of finder switch F now in engagementtherewith (it being assumedv that the wipers of finder switch F are standing opposite the irst level), and the winding 101 of the starting relay 100 to battery B1".

A lt will be noticed that there are two branches connected to the above circuit at points between the spring 129r and the starting relay of the finder switch. One branch extends from the starting wire 244 through the winding of relay 141 to battery B, while the other branch extends from starting wire 144 through the winding of relay 138 to battery' B". in order to secure the proper operation ofthe various relays associated with the starting circuit, they are wound to approximately the following resistances: winding 84 of relay 82, 100 ohms winding 142 of relay 139, 400 ohms; winding 101 of relay 100, 400 ohms; and, relays 138 and 141,-v

' 10,000' ohms each.- To proceed with the operation, upon the closure of the starting circult, the relays 82, 138,` and 141 are not suiciently energized to enable them to attract their armatures; the former relay being. in series with the higher resistance relay 139 andthe added resistance of the .neeaeor multiple branches be ond, andthe two latter relays being shunte by the comparatively low wound relay 100 ofthe lfinder switch,

than relay 100. Considering rst the func'-l tions of relay 139, this relay, upon attracting its armature 1'55, disconnects ground G3 from the group test contact 135 and its multiples -in. the -nder switch banks and substitutes therefor the winding of relay `140. Upon attracting its .lower armature 154, relay 139 vcloses a locking circuit for itself over the following path: ground at G5, coon rela armature 156 an the said armature, winding 143 of relay 139, and the working con- 151; resting contact of tact of armature 154 and the said armature v to battery B". By the energization of the coon relay 151, ground G2 is discon nected from the conductor 152 to prevent for the moment the starting of any other finder switch. l Simultaneous with the closure of the above locking circuit for relay 139, and before relay 151 has had time to attractits armature, the battery B5 is connected direct to the starting wire 244, thereby causing a momentary increased current impulse to flow through winding 84 of relay 82. Upon energizing relay 82 first closes a locking circuit for itself4 as follows: grounded-conductor 38contact 91, spring 92, working contact of armature86 and the said armature, and the winding 83 of relay 82 to battery B4. Further results of the energization of relay 82 are the opening of the circuit of vertical magnet 53 aft armature 85, the opening of the starting circuit at larmature 87, andthe removal of ground `G4 from the, test contact 163 and its multiples in the finder -switch banks.

Returning now to the starting relay 100 of the finder switch l", this relay is sufliciently energized beforel its winding 101 is short-circuited by the application of battery B5 to the starting wire at relay 139, to close a locking circuit including its other winding which may be traced as follows: ground at G1", armature 1.71 and its resting contact, armature 166 and its working contact, vwinding 102 of relay 100, and the windingr 104 of the Vertical test relay 103 to battery B11. 'Relay 100 is thus maintained energizcd temporarilyindependent of the start ing circuit and at the same time relay 103 is operated. Upon energizing, relay 103 closes the following circuit: ground at G12, working contact of armature 170 and the said armature, winding of slow acting relay 106, and the winding 109 of the rotary test relay 107 to battery B1?. Upon energizing, relay 106 closes a locking circuitl for the ISOA vertical test relay 103 as follows: ground at G9 (Fig. 1), upper armature of relay 136, group test contact 134, test wiper 124, working contact of armature 172 and the said armature, armature 169 and its working contact, and the winding 105 of relay 103 to battery B11. Another circuit closed by: relay 106 extends as follows: ground at G10, armature 171 and its working contact, and the windingof magnet 113 to 'battery B13.- Upon energizing, the magnet 113 disengagcs the starting Wiper 125'from spring 129 and thereby permits the ,starting loop to be' closed past the iinder switch\l`. A

branch-of the circuit'of magnet 113 may be traced from junction point 176 by way the armaturel of relay 100. Relay 100 is therefore permitted to deenergize, but-relay 103 remains energized by reason of the circuit through its lower winding 105. A circuit for the vertical magnet 114 may now be traced as follows: ground at G11, armature 168 and its working contact, armature 167 and its Aresting contact, armature 177 and its resting contact, winding of vertical magnet 114, and the armature 178 and its rest-- ing contact to battery Bl. Responsive to the closure of the above circuit the vertical magnet 114 is operated to step. up the linder switch shaft one ste thereby raising the wipers 1214125, inc usive, to the second level. The vertical magnet interrupts its ow'n circuit near the end of its stroke and therefore immediately retracts its armature, but before its circuit can again be closed, the vertical test relay has deenergized due to the test wiper 124 leaving the grounded -test contact 134 and engaging the nongrounded test contact 135. It will be understood of course that if the trunk line whichthe finder switch is in search of were located in one of its upper levels the vertical mag net would be energized intermittently toraise the switch shaft step by step until the test wiper 124 arrived at the right level.

Proceeding with therexplanation, the first l result of the deenergization of the test relay 103 which should be considered is the closure of a circuit for group relay 140 (Fig. 1) as follows: ground at G11, resting conv tact of armature 169 and the said armature, armature 172 and its working contact, test wiper 124, test contact 135 armature 155 and its working contact, and the winding of relay 140 to battery B8. Upon attracting its armature 156, relay 140 breaks the locking circuit of relay 139 which includes also the common relay 151. Upon deenergizing, re-

lay`139again connects ground Gr'3 tothe second level of group test'contacts in the finder banks; while the relay 151, upon deenergizing, again connects -ground G2 tov thc common conductor-152. A second calling line 1s now able to startanother finder switch, even though the finder switch'F has not yet'locate'd the trunk line. to which the.

first calling line is connected. 'f

Returning to the -relay103 (Fig. 2),'addi- 'tional results of its deenerg'ization are the breaking-of the circuit of slow actingv relay 106, relay107 remaining energized by reason of its previously described locking circuit; and the closure of a'circliit for the rotary magnet 115 which. mayI be tracedas follows: ground at G, armature 168 and l its resting contact, winding of slow acting relay 110, armature 175 and its working contact, winding of the rotary magnet 115, and

the lower armature thereof to battery B15.

vUpon the closure of the above circuit lthe slow acting relay and thejrotary magnet are energized in series; the former connectingl ground Gr14 tothe circuit ofmagnet 113 to provide against the deencrgization of .relay 106,. which occurs an instant later; and the lat-ter rotating the switch shaft to brlng the Wipers 121, 122, and 123 into engagement with the `tirst set of contacts of vthe second level. Nearthe end of its stroke l the rotary magnet interrupts its own circuit .and also, at its upper armature, the previously described locking circuit of testrelay 107. lBy. the latter operationr the continued energlzation of the test relay 107 is made contingent on the presence of ground potential upon the test contact with which the test wiper 121 is now in engagement. Assuming that the set of cont-acts which the finder is in Search of is not the first set in the second level, current will -flow from ground on the test contact'by way of test v wiper-121, the lower working contact of armature 174, the said armature and its upper working contact, .and the'winding 108 of relay 107 to battery B12. Since the rotary magnet opened its own circuit at the same time that it opened the initial locking circuit of the test relay it will deenergize immediately and again close both circuits, when the same operation will be repeated .and the wipers will be advanced to the second set of contacts of the second level. Thus it will be seen that the test relay 107 willcontinue to be energized and the rotary magnet 115 will continue tostep the shaft around as long as the test wiper 121 engages grounded test contacts. As soon however as the wipers arrive at the contact set associated with the trunk being hunted for, which is the contact set leaflet-165, the test' wiper 121 will find no ground potential on the engaged test contact,vwhicl1 is the test contact 163,I and the test relay 107 will therefore deenergize as soon as its .locking circuit is opened by the rotar magnet, and will break the circuit of `the Thus the Wipers of the finder are brought tol rest in engagement with the contacts of the trunk line to whichv the line of substa;

tion A is connected. c c

The instant the test relay 107 -deenergizes the rollovvin lcircuit is completed for the switching ne ay '111: ground at G14, 'armature 173 and its working contact, junction point 176,' upper armature of the `rotary magnet 115 and its resting contact, armature 1711 and its resting contact, and the windin ot switching relay 111 to battery B1". pon energizing, the switching relay at its armatures 194; and '195. connects the line wipers 122 and 123, respectively, with the trunk Jconductors 191 and 192; breaks v atA its armature 18a a contact in the circuit of the release magnet 117 Vin order to guard against the deenergization of the slow-acting relay 110; and finally at its armature 185, completes a circuit for relay 89 of the selector E which may be traced as a branch of the circuit of relay 111 as follows: junction point 193, working contact of armature 185 and the said armature, junction point 180, test wiper 121, test contact 163, conductor 160, armature 88 and its working contact, and the winding of relay 89 to battery B17. Upon attracting its armature, relay 89 substitutes ground Gs for ground G in the locking circuitof relay 82. The

abovecircuit of relay 89 also serves to supline relay 181 is energizedin multiple lwith the line relay 50 of the selectorE, and upon attracting its armature completes-xa circuit for the slow actingl relayf182 as. follows:v

ground at G1", armat'-l`1re" 186 and'itsworking contact, winding of relay j. 182,V armature 189 and its resting contact,'and the upper contacts of key K to battery B18. Upon energizing, relay 182 completes the followin holding circuit as a substitute for ground n; groundat G17, working contact of armature 187 and the said armature, and the conductor 190 to junction point 180, where vthe -circuit divides, one branch eX- tending over a vpreviously described path t-o` relay 89 of the selector E, and the other atter to prevent its reenergization.

Maase? branch extending by way of armature 185 and its working contact to junction lpoint 193, lwhere the circuit again divides into branches extendin to relay 111 and to mag- 1 l.'

how the call-signal lamp L is illuminated.y As soon as the relays 106 .and 107 are y energized followingethe closure of the starting circuit, a circuit through lamp L may i l time to deenergize after the last rotary iml be traced as follows: ground at G1", arma\ kS0 ture 171 and its 4working contact, junction point 176, upper armature of the rotary.

conductor 190, armature'188 and'its resting contact, and the lamp L 'to battery. B18.

It will be seen then that the call signal lamp is lighted immediately upon the start- .ing `oi? the nder switch, thus giving the operator warning in advance of the'completion ofthe connection that such connection is to" be established.v After the finder has operated, current is of course supplied to lamp L from ground G17,

The operator will respond to the si nal thus received by operating the key l to the position shown in the drawing, thereby bridging her head set (not shown) across the trunk conductors 191 and 192, and at the` same time removing the short circuit from relay 183. Relay 183 -is accordingly energized in series with relay 182, and u on attracting its armatures 1881and 189, shifts the conductor 190 from lamp L to lamp L', and also opens a contact in its shunt circuit so that if the key K is restored it will not.

again be short-circuited. The operator may now converse with the calling subscriber and ascertain his wants as is usual in such cases. 1f it should become necessary for the operato-r to have the subscriber wait While certain facts, his credit for example, are beinginvestigated, she may restore her key to normal osition. When this is done the lamp L (a red lamp, preferably) is forget the cally.

will break the circuits of slow-acting relays- 51 and 182. When the relay 51 deenergizes, the holding `circuit including the vWinding' iat lighted to insure that the operator will not ,switch,

finder switch will be deenergized. Relay 89,

' thereby cutting the 18 of line switch C will be broken and the line switch will be released in -the usual manner. Upon the deenergization of relay 182, the relay 89 of selector E, the relay 111 of the finder and the magnet 113 of the upon 'retracting its armature, breaks the locking circuit of relay 82 thus permitting that rela to restore and again connect ground 1 to conductor 160. When the relay 111 retracts its armatures, a circuit is closed for the rotary release magnet 117 as follows: ground at G14, armature 173 and its resting contact, resting contact of armature 184 and the said armature, winding of' release magnet 117, and the rotary oli'- normal springs 118 to battery B1. Upon energizing, the release magnet 117 withdraws the rotary holding pawl from the shaft, thereby permitting the restoration of the shaft and wipers in so far as their rotary movement is concerned, and as soon as the return is effected the circuit of the release magnet is again opened at the Aoff-normal springs 118.

The magnet 113 being now deenergized, as soon as the shaft is released the starting wiper 125 will engage the starting circuit contact spring 126 and will separate it from spring 127, finder switch in on the starting loop again. After disconnection,

therefore, the finder switch wipers are left standing opposite the bank level last served; or in other words, the wipers ordinarily are not released as regards their group selecting movement.

, Under certain circumstances, however, for example as when the wipers are standing opposite the tenth level and it 1s necessary to cause them to hunt over a lower level, the finder switch shaft is restored vertically by energizing the vertical release magnet 1 16, but such release is always eiected durlng the establishment of the connection and not upon disconnection. In order to explain the vertical release it will be assumed that when the calling subscriber at substation A pressed his button to call the operator the finder switch F was standing opposite the ninth level instead of the first level. Now when the starting wire 244 is grounded the finder switch F' will be started as before (there being no other finders cut in on the starting loop between the second and ninth levels) and the vertical magnet 114 will be operated to raise the wipers to the tenth level. Since the group test contact for the tenth level is grounded the test relay 103 will not deenergize. As the armature of the vertical magnet reaches nearly the end of its stroke andjust as the magnetcircuit is interrupted, the cam 132 on the shaft engages the dog 133 and releases the olf-normal spring 1.19, which thereupon makes contact with sprlng 120 and closes thefollowing circuit: ground at G, armature 168 and its working contact, armature 167 and its restmg contact, winding of relay 112, and the off-normal springs 120 and 119 to battery B20. Upon energizing, relay 112 breaks the -tion of the vertical magnet 114 is of `course suspended, and also the test relay 103 is locked as previously mentioned to prevent its deenergization when the test wiper 124 passes the test contact 135 on the way down. With the complete return of the shaft, the earn 131 has separated the olf-normal springs agaln, whereupon the release magnet circuit 1s :broken and the circuit of the vertical magnet 114 is again closed. Thereupon the finder switch resumes its operation and the calling line is found as before.

T he purpose of the relays 138 and 141 and slmllar relays (not shown) associated with the other eight suboups will now be briefly explained. Tese relays are provldcd for the purpose of giving an alarm 1n case the finder switches are all busy when a call isjattempted to be made, or in case there is an open circuit somewhere in the starting loop. In the former case all ten of these relays will be connected to whichever startlng wire is grounded and since they are not shunted' by the starting relay of a finder switch, will be energized in multiple to light their associated lamps in series with the alarm relay 150. Relay 139 is so adjusted that it will not operatively energize in series with'1000 ohms. In the case of an open circuit in the starting loop those relays which are connected to the starting wires beyond the break will not be energized, and the last lamp lighted therefore will indicate the approximate location of the trouble. In case the latter supervision is not desired,

however, all but one of the relays may be it will be operated as yusual to locate thef ground group and unlock the group relayto restore ground to the group test contact; but when in the rotary movement. the .test wiper 121 arrives at -testycontact 163," it will lind lzeotential andthe rotation will oo ntinu'e. .,bviously then, were no speclal means `adopted to prevent it, the switch would continue to buzz. f Such contingency is obviated by providing the rotary-shaft with an extra tooth so that .ontheeleventh rotary step the wipers will be rotatedj od thefbank. The revision of such an extra tooth on-the shag is oldin thej art, switches of-manytypeshaving been used in the past which have more than ten teethlto. the ro.

= 122 and 123 are not in engagement with a' Gil calling line, -or any other line,l no holding circuit will be established," and the switch will be releasedfollowing the deenergization of the slow-acting vrelay 110..

Having described. my invention, what ll. consider to be newand desire `to have prof. tectedby. Letters Patent will be pointed out in the appendedclaims. L

What lt claim as my invention is:

1. ln a telephone system, a subscribers line, a trunk'line having two branches, means for connecting said line and trunk. line, a selector switch for one branch, a calling device at the station on said line for -operating said switch to extend a connec, tion over the1 associated branch, a finder switch, and another 'calling device at the station on the said line manually operable after the line and trunk are connected, and means responsive to said-second calling device for causing said finder to extend a connection overthe other of said branches. Y In. a telephone, system, 'a subscribers. line,a trunk line having two branches, the first branch extending toward an operators switchboard, and thel second branch extend-V 'ing toward a called line, means for connecting said subscribers line whencalling with `.said trunk line, switch hook springs at the Stationen thecalling. line for controlling said connecting 'mean-s, a. variable impulse .sender and a .circuit changing switchl at the said station, and automaticswitching mechanism at the exchange .for extending thev calling line. over said first branch to said switchboard res onsiveto .the'actuation of saidgswitch, an .for extending said calling lineito a called line over said second branch pesano? responsive-to' the actuation of saidcalling device. jf, f. 3...lln a telephone system, a subscribers line, a trunk lineterminating in an auto-f matic selector switch, a finder switch, a branch ot said trunk line terminating in the .bank of said finder switch, means for extending lsaid line when calling tosaid trunk line, an impulse sender at the sub# 'station on said selector switch, and an -auxiliary device eration of said 'finder switch.

4. In a line, 'matic-switch, a finder switch, a branch- -of "said trunk line terminatinglin vthe bank'off said finder switch, means for extendingsaid" line when calling to said trunk line, an im-` pulse sender at the ing line forl operatingsaid selector switch, an auxiliar initiating t e operation of said and means the connection is released.

the calling. line for operating ,7.,

substationon the calltelephone system, a subscribers a vtrunk line terlnlnating 1n an auto.-

device associated .therewith'for' 4finder switch,". whereby ifeither the selector ..gswitch or the finder switch is operated the .5. In a. telephone system, a subscribers# line,. a Atrunk line having two branches, an automatic switchfor extendlng one of said branches to'anoperators pos1t1on, a, numerical automatic switch individual to said trunk line for extending the other of said branches toward another subscribe-rs line, means for,

connecting said-first linewhen calling'with' v said trunk line, and means for then imme- ^dia`tely operating .either of. said switches separately at the option of the calling subfscriber. A I 6. In. a telephone-l system, a subscribers line, la trunk line having two branches, an automa-tic switch for .extending one of said branches to. anv operators position, a numerical automatic switch individual to said trunkline for extending the other of said branchestoward another subscribers line, means for connecting said first line when calling-with said trunk line, and separate controlling devices for respectively, at the substation on the call-` ing line,- each controlling devicebeing manswitch, switching mechanism for connecting the said subscribers line when calling with its the said switches,

ico

respectively, separate controlling l relays and operating magnets for each said trunk linoe, a device at the statlon onlthe calling line for controlling said mechanism, and manually operableA controlling means wheieb the subscriber on the calling line is ena led to operate either of said switches as soon as his line is connected to the said trunk line.

8.l In a telephone system, a subscribers 1 line, a trunk hne having two branches extending to forward and backward selecting automatic switches, respectively, separate controlling relays and operating magnets in each switch, mechanism for yconnecting the said subscribers line when calling with'said trunk line, switch hook springs at the station on said line for controlling said mechanism, separate subscriber controlled devices in the line circuit at said station, and circuit connections whereby each of said switches is rendered responsive only to a particular one of said devices.

9. In a telephone system, a subscribers line,a trunk line having two branches' each terminating in an automatic switch, means for connecting the 'said line when calling with said trunk line, an impulse sender and a push button in the line circuit at the substation on the callingline, and circuit connections at the exchange whereby one of said switches is rendered responsive to sai-d impulse sender and the other of said switches to said push button.`

10. In a telephone system, a subscribers line, a trunk line having two branches each terminating. in an automatic switch, means for connecting the said line when calling with said trunk line, and separate controlling devices operated. independently for operating the respective switches, said devices located at the substation on the calling line and controlling the two sides of the subscribers line in series to operate said switches.

11. In a telephone system,A lines divided into groups, an automatic switch having group and line selecting movements and having no normal position as regards the said groups, means for operating saidswitch to select a desired one of said lines, with means for preventing a group selecting movement thereof it' the said switch is already associ'ated with the proper group. Y

12. In a telephone system, lines divided into groups, a switch having automatic group and line selecting movements and having no normal position as regards the said groups, means for initiating the operation of s'aid switch to select a desired one of said lines, with means permitting the omission of the group selecting movement if the said switch is already associated with the proper group.

. 13. In a' telephone system, lines divided into groups, a plurality of switches having automatic group and line selecting movements, said switches being normally associated, respectively, with the groups last served, and means for initiating the operation of one of said switches to select a desired line, the .switch operated being. one which is already associated with the proper group.

14. In a telephone system, lines divided into groups, a plurality of switches having automatic group and line selecting movements, said switches being normally associated, respectively, with the groups last served, means for initiating the operation of-one of said switches to select a desired line, the switch operated being one which is already associated with the proper group, and means whereby if the group in which the desired line is located has no switch asociated therewith that switch will be operated which requires the shortest group selecting movement.

15. In a telephone system, a plurality of lines divided 'into groups, a plurality of finder switches associated indiferently with the various groups and having group and line selecting movements, and means responsive to a call received over one of said lines n for starting that one of said switches which requires the shortest group selecting movement to locate the calling line.

16. In a telephone system, a plurality of l lines divided into groups, a plurality of finder switches having group and line selecting movements for extending calls received over said lines, each switch when idle being associated withI the group last served, and means responsive to a call for starting. that one of said switches which requires the shortest group selecting movement to locate the calling line. l

'17. In a telephone system, a plurality of lines divided into groups, a plurality of finder switches associated indiiierently with the various groups and having primary and secondary selective movements for selecting groups and lines, respectively, and means responsive to a call received over one of said lines for operating one of said finders in [either one or both of its selective movements dary selective movements for selectinggroups and lines, respectively, said finders having no normal position as regards the said groups, and means responsive to a call received over one of said lines for starting the finder switch associated with the proper group to find the said line by a secondary K selective movement only.

19. In a telephone system, a plurality of lines divided into groups, a finder switch having group and line selecting movements.

for extending one of said lines when calling,

and means `for releasing said switch thereafter only in so far as its llne selecting selecting movement thereof.

2Q. Ina telephone system, a plurality of lines divided into groups, a finderswitch having group and line selecting movements and operable responsive to a call received over one of said lines to extend the call to another line, means for thereafter releasing said switch in so far as its line selecting movement 'is concerned, and means for retaining said switch in operated position in so far as its group 'selecting movement is concerned.

21. In a telephone system, a lurality of lines divided into groups, trunk ines, finder switches having primary and secondary selective movements for "selecting .groups and lines, respectively,.to extend calls to idle trunk lines, releasing means' in each finder switch, and means for retaining each switch after disconnection in association with the last selected group. ,Y

22. ln a telephone system, groups of lines an automatic switch having primary and secondary motor magnets for operating the .same to connect with a desired one of said lines, independently operable primary and secondary release magnets for restoring sald switch, and means for operating sald secondary release magnet only to restore said switch in readiness for another call.

23. In a telephone system, groups of lines, an automatic switch having primary and secondary motor magnets for operating the same to connect with a desired one of said lines, independently operable primary and secondary release magnets for restoring said switch, and circuit connections for energizing in order the said primary release ma net, the said vmotor magnets, and the said secondary release magnet.

24. In a telephone system, a subscriber"s line, a trunk line, means including an automatic switch for connecting said lines, an operating magnet and a release magnet in said switch, and automatic means for actuating said magnets alternately during the establishment of the connection.

25. In a telephone system," groups of lines, an automatic switch having group andline selecting'movements for connecting with a desired one of said lines, means for restoring said switch as regards its line selecting movement independent of restoration as regards its group selecting movement, and means for again operating said switch to 'select a line without restoring it as regards its group selecting movement.

acceso? 26. ln a telephone system, finder switches each operative through a plurality of stages for extending a connection, circuit connectime interval between the starting of succes- V sive finders, and means actuated by said finders at the completion of preliminary stages of their operation for terminating said time intervals. A

27. In a. telephone system, grou s of lines, finder switches having group and line selecting movements for connecting with said lines, means responsive to calls for starting said finders, and circuit connections preventing simultaneous roup selection by two or more finders, whi e permitting group selecition by one finder to occur contemporaneously with 4line selection by another finder. I

28. In -a telephone system, a plurality of lines, finder switches having primary and secondary movement for extending calls received over said lines, means responsive to a call for starting an idle finder, 'and means actuated durin the primary movement of the started fin er' but not in the secondary movement thereof for preventing the start ing of another finder switch.

29. lin a telephone system, a plurality of lines, finder switches having a plurality of selective movements for extendingcalls received over said lines, a starting circuit for starting said finders successively responsive to successive calls, means for rendering said circuit ineilective each'time a finder switch is started, and means for rendering said circuit again eective while each finder is performing its final selective operation.

30. In a telephone system, a subscribers line, a trunk line terminating in an operators position, a plurality ofy automatic switches successively operable to extend said line when calling to said trunk line, a signal operated at an intermediate stage in the connecting operation to warn the operator of the approach of the call, and means for momentarily flashing the said signal when the connection is complete.

31. In a telephone system, groups of lines', finder switches for extending calls received` over said lines, and a starting circuit including a normally closed contact for each of said groups in each of said switches.

32. lin a telephone system, groups of lines, finder switches for extending calls received over said lines, a starting circuit includin a normally closed contact for each of sai groups in each of said switches, and means in each of said switches for opening one of said contacts, whereby the said circuit may be divided into sections.

33. In a telephone system, grou s of lines finder switches for extending cal received a normally closed contact for each of said groups in each ofsaid switches, means in each of said swi-tches for opening one of said contacts whereby the said circuit may be div vided into sections, a controlling relay for cach of said finder switches, and means for connecting each relay to one of said sections.

34. In a telephone system, groups of lmes, finder switches for extending calls received over said lines, a starting circuit including a normally closed contact for each of said groups in each of said switches, and means in each of said switches effective when the switch is idle for opening one of said contacts, whereby the said circuit may be ldivided into as many sections as there are idle switches.

35. In a telephone system, groups of lines, finder switches for extending calls received over said lines, a starting circuit including a normally closed contact for each of said -groups in each of said switches, means in each of said switches effective when the switch is idle for opening one of said contacts, whereby the said circuit may be divided into as many sections as there arel idle switches, and 'a starting relay in each idle finder switch connected to one of said sections.

36. In a telephone system, groups of lines, finder switches for extending calls received over said lines, a starting circuit including all of said switches in series, and a plurality of branches of said circuit equal in number to the number of said groups, said branches being all connected to said circuit at the same switch.

37. In a telephone system, groups of lines, finder switches for extending calls received over said lines, a loop circuit passing through each switch as many times as there are groups, and a starting wi-re for each group of lines joined to said circuit.

38. In a telephone system, groups of lines, a finder switch for extending a call received over one of said lines, relays individual to groups and lines, respectively, a starting. relay for said finder, and a starting circuit including one of said group relays, one of said line relays and the said starting relay.

39. In a telephone system, a finde-r switch, a starting circuit including a low resistance controlling relay in said switch, and a high resistance alarm relay connectedin parallel with said controlling relay.

40. In a telephone system, a finder switch, a starting circuit including a low resistance controlling relay in said switch, means for closing said circuit, a plurality of normally closed contacts inthe circuit between the point of closure and the said relay, and an alarm relay in parallel with said lirst relay and connected to the circuit between the point of closure and the said contacts, said relay being of high resistance whereby when the circuit is closed it will be rendered inoperative by the sliunting effect of Said first relay.

4l. In a telephone system, a trunk line havin two branches, means for connecting "a calling subscribers line with said trunk line at the undivided end thereof, means for completing a talking connection over one of said branches, and means for supplying talking current to the calling line over both of said branches in parallel.

42. In a telephone system, a plurality of lines divided into groups, an automatic ,i

switch having primary and secondary movements to select groups and lines, respectively, said switch' when idle being associated with'diferent groups at different times, means controlled by a calling subscriber in setting up a connection for causing both pr1mary .and secondary movement of said switch for selecting one of said lines, andv to rotate without first moving vertically to zonnect the said calling line with said trunk 44. In la telephone system, a calling subscribers line, a trunk line, an automatic switch having primary and secondary selective movements, and a device at the station on the calling line manually operable after the receiver is removed for causing said switch to connect the said line and trunk line by means of a secondary selective movement only.

45. In a telephone system, an automatic switch for use in connecting a, calling and called line, a wiper shaft'for said swi-tch, a magnet coil wo-und on said shaft as a core and movable with the shaft, and a circuit changing Iarmature adapted to be attracted when the said coil is energized.

46. In a telephone system, a finder switch for use in extending a calling line to a trunk line, a starter wire extending to said switch, a magnet for extending said starterl wire to another finder switch, and a wiper shaft for said .rst finder constituting a core for said magnet.

47. In a telephone system, a finder switch for use in extending a calling line to a trunk line, a tes-t wiper for said finder, a magnet for rendering said test wiper inoperative with respect to its associated test contacts, and a wiper shaft for said finder constituting a core for said magnet.

48. In a selector switch having hunting movements in two different co-ordinate di-l iii-a rections, means for starting the contact arms from a variable initial position in the first co-'o'rdinate direction upon a call being inltiated, means for setting the conta/charms 1n thqirst cofordinate direction forv the selec-` tion ofa Contact row, and means for Setting the contact arms in the. second co-ordinate direction for the selectlon of a particular ticular contact, means for restoring` the contact arms, means for automatically stopping the return movement of the contact arms upon the latter reaching a position opposite incase? to the Contact row vjust left, and means for starting the Contact arms from said. position in the first ctn-ordinate direction upon a 50. In a, selector switch having'- hunting movements in two co-ordinate directions,`

fixed line contactsarranged in rows,means Afor-,starting the contact arms from a vari- 'v able initial position in thel first co-ordinate direction for the selection of a contact row, means for setting the contact arms inthe second (zo-ordinate direction for therselection of la particular contact, and means for marking a contact row as engaged as soon 'as the switch has found the contactrow to .which the calling line is connected.

Signed by me at Chicago, Cook County,

State of illinois, this 29th day of December, l

RODNEY G. RCHARDSON.

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