US1290148A - Automatic telephone-release. - Google Patents

Description

'AUTOMATIC TELEPHONE RELEASE. n' 'V v APPLICATION FILED FEB. 27. |908. RENEWED MY 16'1918- Patented Jan. 7,1919.

E. D. FALES. AUTOMATIC TELEPHONE RELEASE. Avrucmon mtu' res. 2.1. laos. n'zne'wsp my la. ma.

Patented Jun. 7, 1919.

a sums-snm a Iran s'rATEs Ar .EDWARI) n. FALES, or WESTERN SPRINGS, ILLINOIS, AsSIeNon, BY MESNE ASSIGN- MENTS, To AUToivIAgIo ELECTRIC COMPANY, oF CHICAGO, ILLINOIS, A CORPORA- TIoN or ILLINOIS.

Specieation of Letters Patent.

AUToMATIc TELErHoNE-RELEASE.

Application 4filed February 27, 1908A, Serial No. 418,166. Renewed May 16, 19,18. Serial No.r 235,010.l

To all zc/tom t may concern Beit known that I, EDWARD D.v FALES, a citizen of the United States of-America, and resident of lfVestern Springs, C ook county, Illinois, have invented acertam new 'and useful Improvement in Automatic Telephone-Releases, of which the following is a specification.

My. inventionrelatesl to automatic telephony of that partiiular character v1n which electrically-propelled' vand step-by-step-a'ctu-4 ated Switches are employed for extending (onnection' from one point ,to another-such,

for exam-ple, as from a calling subscribers line to a called subscribers line; and especially to systems of this4 kind 1n which the switches .have vertical motion for selecting rgroups and rotary motion for connecting .if with a line in the selected group, which line may`be either a trunk-line or the called sub- V,sribers line, inasmuch as the trunk selec-v 1 tors and the connectors or final switches have the said vertical and rotary motion, as will hereinafter more fully, appear.

Prior to my invention it has been proposed to release the automatic connection through the lmedium of what-are` called slowacting relays-that is to say,'relays which are slug- 'gislij or slowl in dee'nergizing, the said relays being retained energized during use of the connection for talking purposes,so that im-` mediately upon one of the subscribers hang'- ing up his telephone, the said. relays are `deenergized, thus bringingabout the release 'of the conne4 tion. Thesevrelays are made slowacting to prevent their premature action-that is to say, to preventtheml from being prematurely deenergiaed bythe open; ing of the line circuit during the progress of the call, it being understood that-these 'slow-acting relays. were used in connection .with what are called tivo-wire systemsthat is to say, automatic telephone systems 1n whifh no operating grounds are employed at the subscribers stations, and in 'which the operation ofA the switches and their return to normal is all accomplished over metallic circuits simply by opening and closing the linefrircuit at the calling substation, The said relays being slow-acting, in the manner speified, it follows that when they are once energized they remain so until one or the other of the two subscribers hangs up his receiver, for the reason that during the progress of the call the brief 'breaking or opening lof the line circuit, during 'the transmitting of the impulses, does not operate to denergize the said relays; 3 It follows, however, that while these relayswe're slowacting during the` progress ofthe' call, for` the purpose of preventing a premature re-` lea-sey of the switches, in the manner specified, it was also true that they were slow-acting when the time` came to use them for releasing purposes, and for this 'reason it was found that the release of the switches was sluggish or slow in chara'ter. This was productive of some trouble, inasmuch as. with a slow or sluggish release the subscriber would perliapsbeofin calling again beforel the connection for the fully released.

Generally stated, therefore, the object of my invention is the provision of a slow-acting release relay arrangement which will prevent a premature release of any o f the previous call hadljbeen Patenteaaan. 7,1919.

switches vduring the progress of the call, as

heretofore, but whilh is also of suth character that when the time comes for ythe release, then the said relays 'are quiclnacting in character, thus insuring practically an instantaneous release as soon as the said relays are denergized by the opening of the line at the subscribers station, the system being two-Wirev 'in character, as previously ex-V represents a substation A and central office I 'apparatus embodying the principles of my invention. The line ofsubstation A- terminates 1n the line Switch C. At D is represented the master switchfor controlling the line switches of the group of` which C is a member. E represents dia'grammatically a first-selector switch and F' is a second-selector switch.

In Fig. 2 -is shown diagrammatically a. connector switch H, and C is shown a line switch allotted to the line of substation A. A central battery B having its positive terminal preferably grounded at G provides battery current for-.operating and talking l purposes.

VF ig. 3 represents more fully the line switch C andthe controlling master switch D.

Fig. 4 isa detail view of the master switch banl O. A' In this system each subscribers line is, of Course, provided with a line switch similar to the line switch C, and one-hundredfoi these usually form a group. Also, to each such group there is allotted a groupot first- 4selector switches in common. The first-sen lector switches may in turn be operated to first select any one of a number of groups of second-selectors'and then' some one of the selector group which may be idle. The second-selector switches may in turn be operated toI first select any one of a number ot groups of connector switches, and then some one ot the connectors of the selected group which may be idle. Each' group of connector switches is lalso arranged to take care of one-hundred subscribers-'that is, if any subscriber in thev system wants to 'call anotherv subscriber he must, through the medium of the first-selector and second-sellector switches, pick out a certain group of connectors any one of the connectors of which group is capable of establishing the final connection with the desired subscriber in a particular hundred.

The substations may be of any suitable or approved type. As shown, it will be seen that substation A is somewhat different from the usual'automatic substation, substation A being arranged and modiiied to operate in connection with a two-wire systemthat is, a system in which no ground connection is used at the subscribers substation. Substation A, for example, comprises the usual receiver 2, switch-hook 3, induction coil 4 which consists of the primary winding 5 and secondary winding 6, transmitter 7, condenser 8, ringer 9 and impulse wheel 10 which has the usual impulse teeth 11. The impulse wheel 1'0 is secured to the shaft 12, towhich shaft there is also secured the dial (not shown). .`When the dial isturned the impulse teeth 11 are adapted to engage the cam 13 upon the end ot' the spring- 14, and thereby carry the latter out of engagement with the spring 15. Upon the switch-hook 3 is secured the cam 16 which, when the switch-hook is up, permits the springs 17 and 18 to engage, lthereby bridging across-the subscribers line conductors 19 and 20 ,the primary circuit including the transmitter 7 in series with the primary winding 5; but when the switchhook is lowered the spring 17 is carried out of engagement with the spring 1S and into engagement with the spring 1S,

y whereby the ringer 9 in series with the condenser-'8 is bridged across the 19 and 2O instead.

The line switch CA (Fig. 3) comprises a plunger 21, plunger arm trip magnet 23 and switch-release magnet 24, all of which are assembled upon a suitable base or frame (not shown). The said switch-release magnet is provided with an armature 25 that is pivoted on a pin 26 which rises from the base of the switch. The said armature carries pivotally secured on its end a second armature 27 that is controlled by the trip magnet 23. The pin 28 about which the armature 27 moves is carried on the end of the armature 25. 'The plunger 21 is pii/otally secured by the pin 29 to the plunger arm 22, which latter is in turn pivoted by a pin 30 that rises from the switch frame (not shown). The lug 31 may be stamped from the frame, and is provided as a stop for the armature 25. Upon the armature 27 is scoured the catch spring 32 which is adapted to normally engage the end 83 of the plunger arm 22. Furthermore, the said line switch is provided with a bank ot terminals, usually ten in number. only one of which is shown at. Q (Fig. 3). The said 'terminal Q is shown displaced from its true position with respect to the .swing of the plunger 21, and the bushing 34 is correspondingly displaced, all for theI purpose of making the illustration clearer. The terminal Q comprises the springs 35 and 36, 37 and 3S, 39 and 40, and 41 and 42. These springs are normally disconnected from each other, butV are driven into contact in the above-mentioned order when the plunger 2l enters the bank terminal Q. When the plunger 21 disengages from the bank terminal Q the said plunger may take one of two positions with'relation to the plunger shaft 43-that is, the plunger may return to locked or sliding engagement with the shaft 43. lVhen the plunger 21 is in locked engagement with the plunger shaft 43, the notch 44 is in engagement with the flange or web 45 ot the shaft 43; and when in sliding engagement the fan-like tail-piece line conductors 46 rests in the position shown by the dotted lines iii-Fig. 3-that is, when the plunger shaft is operated `the plunger 21 is not carriedalong with the locked plungers, but remains in the dotted position, the plunger shaft sliding upon the edge of the tailpiece .46. The general operation of the switch is as follows:l The trip magnet 23 is energized again 'denergizes the trip armature 27 falls against the end 33 of the plunger arm 22, as

shown.. Furthermore, when the line switch vvanced one step, as will be explained, to,

'i idle trunkdine.

operates and the plunger 21 is thrust into the bank terminal Q, the shaft 43 is ad- -returnsto normal position and remains at rest against the stop'31.I I `urthermore` since the plunger arm 22 is now 1n' engagement with thearmature 27, the said plunger arm', is also moved about thepin 30, whereby the plunger 21 is removed from the terminal Q. Also, since the plunger shaft has advanced one Step, the tail-piece 46 `of the plunger 21 comes lto rest in the position shown by the dotted linefthat is. in sliding engagement with the plunger' snaft43; and'` 'as the said plunger shaft advances each time an idle trunk is seized,ithe plunger 21 is not advanced, but remains in this position op' posite thetrunk terminal from which it has last disengaged, since the slot 44 is not in engagement with the plunger `shaft web 45.

After all the trunlelines have been` succes-` sivelv seized. the shaft 43 then passes from lits last position and moves toward its starting point, picking up the plunger 21, when the web of the said shaft/overwvhich the slot 44 normally rides arrives at the position in which the plunger 2l Was originally released-that is. the plunger. passes into locke-d engagement with the shaft when 'the slot 44 slips over the web of said shaft. From thence on the plunger 21 is carried in locked engagement the shaft v43 until it is again released when another call is made. But if after the plunger is released, and beforethe shaft 43 returns to pick up said-v plunfrer. the switch C-is again operated. the

'plunfrer 21 again enga ges the same terminal Q. The bridge-cut-ofl'l relay 48 is provided for controlling the springs 49, 50, 51 and 52, and` upon energizing, operates to shift the springs 49 and51 out of engagement with the springs 50-and 152. When the springs are thus operated the trip magnet of the line switch() is disconnected from the substation lineconductors. Y

The master switch D, which may be of any suitable or approved type` is provided for operating the plunger' shaft 43 and for controlling certain circuits that. will `hereinafter be disclosed. It comprises the lfollowing details: a motor 'magneti53 for operating.

the ratchet wheel 54, which latter is designed for operating` the plunger shaft 43 through the medium of t-he cam 55,v and a.

segments fr, are separated from the common segment 57 by the 'insulating strip G1. The 80 spring62 is provided so that when the wiper is carried to the contact 6O'on the extreme 4right,`the upper. part ofthe wiper 58 slides lonthe guide spring 62, thus preventing the wiper from placing any ofthe individual 'segments a in contact with the common seg-- nient 57,'Whereby'vsome Ainterference might be caused with the master switch The wiper 'p 58 isoperated' in a step-bvstepumanner.by

thel ratchetl wheel 54 through the medium of 90 the cani member 55 rigidlysecured to the'v said Wiper58, and is adapted to successively engage the pins 63, G4, 65 and'GGupon the said ratchet wheel 54. The motor magnet 53 is provided ivith an armature 67 uponthe end of which there is suitably secured "a pawl 68. Eachv time that the said magnet is energized the armature A67 is attract-ed4 against the magnet cores. and the-pawl G8 engages a tooth on the ratchet Wheel 54, thereby advancing the latter one step. Itivill be seen, therefore, that as the ratchet Wheel 54 acl-- vances in a backward direction, the Wiper 58 advances step by step from right to left.

' and when the pin 63, for example; clears the 105 cam .5,5 the l'reti-acting spring 69 resto-res ,the wiper 58 to its first position at the right of the bank and in engagement -ivitli the first segment 60.v The said mctor magnet is provided Witli'acouple of interrupter springs 110 70l and 7.1' that are included in the'energizing l circuit of the said motor magnet, which energizing .circuit also comprises v the. springs 7 2 and 73 controlled b v theditferential relav 5 6. Therefore, Wheneverthe differential re@ 115 lay is. energized-fthe lsprinrs 72 and 73 are pressed int-o contact, and the motor magnet 53:0perates `step by step as long as the dif-` ferential relay/56 remains energized. vFurtherinore. it .is .assur'iedfthat the-terminal Q 120 ofthe line switch Cjis the first terminal of the line switch bank. AWhile inner-mal lof-king engagementl with the shaftj43vtheplunger 21 is vretained -inA ront of said terminal by the' plunger shaft' xwhenever the master 125 vswitch Wiper 58 isin engagementgwith the bank segment G0; but v. as the. motor magnet 53 advances the Wiper58 onto the second Vvsegment 74. the said lplunger and al1 idle carried opposite the 'next terminal of the line switch bank. 1t should be noted'that in each line;switch bank all of the springs 4`35'are permanently connected and may be composed of one common piece. The springs 36, however, are individual-that is, therev is oneyseparate and distinct spring for every bank set Q. there being ten in the bank.

`The springs v37, 39, A10 and 41, like the springs 35, arey all common, and the springs 38 and 42, like the springs`36, are individual. For every bank terminal Q thereI is a trunk-line ofv three conductors 75, 6 and 77 leading to the general type described in United States4 Letters Patent No. 815,321, granted March 13,1906, toKeith, Erickson & Erickson, and,

as shown, is modified to adapt it to operate 1n -connection with a two-wire system.

4Amongother details it embodies the following features: The switch. shaft (not shown) Carries the Vertical and rotary wipers 81' and 82, respectively, and the private wiper 83. The side switch is well known and comprises the side switch wipers 81, 85, 86, 86t and 87, which may be designated as the verticah. rotary and private side switch Wipers, the secondary winding side switch ,Wiper, and the rotary magnet wiper, respectively. The side switch is under the control of the private magnet 88, and when. the side switch is in normal or first position the wipers 81,85, 86 86a and 87 occupy the contact points 89, 90, 91, 91a and 107, respectively. In the second position the wipers rest on the contact'points 93, 94, 95, 95a and .96, respectively, and in third position the contact'points 97, 98, 99, 99a and 100 aie engaged by their respective wipers. The wind- Aings of the usual vertical and rotary line relays are, in this case. combined into one doublefwound relay 101 comprising the winding 102 which is connected with the battery lead 103, and also with the vertical trunkline conductor when the side switch wiper 84:` is in first or second position. The second winding 104C is connected to ground and also to the rotary trunk-line conductor when the side switch wiper 85 is in first or second. position. Through, the medium of this double-wound relay, and while the side switch is infirst position. the subscriber con- 'trols the vertical magnet 105 which operates to raise the switch shaft and wipers 81, 82

and 83 vertically. This line relay 101 also second position the rotary magnet 92, which operates tocarry the switch shaft and wipers 81, 82 and 83 in a rotary direction, is energized. The release magnet` 108 provides means for restoring the selector switch to normal position. Upon the switch shaft which carries the wipers 81, 82 and 83 there iii-mounted the arm 109 which, when the shaft is raised one or more steps, permits the spring'lll to engage the' contact point 110, whereby the release magnet 108 is connected to the battery lead. lay 112 is provided for closing-the eiiergizing circuit of the release magnet'lOS after the switch is operated. Said relay 1-12 is provided with a second winding 113 which is shortrcircuited when the side switch wiper 86a is in first or second position; but when the side switch wiper 86a passes to thirdposition the short-circuit is broken. This arrangement is provided'in order that the relay 112 may be a slow-acting relay when the selector E is operating, but when the switch is to be released, after the side switch passes to third position, the relay 112 is quick-acting. The relay 106 is a slow-acting relay-that is, it isprovided lwith a copper shield so that when energized and when the energizing circuit is broken, the said relay remains in an operated position for a moment or so. In other words. it does not The release re instantly return to normal position after the energizing circuit is broken.

The second-selector F (Fig. 1) is similar vto the first-selector E and is provided with the usual double-wound line relay 114 having the windings' 115 and 116 connected with the vertical and rotary side switch wipers 117 and 118 in the same manner'in which the windings of the relay 101 of the selector switch E are" connected totheir vertical and rotary side switch wipers. Since like parts are similarly represented, the rotary magnet 119 and the vertical magnet 120 will be recognized and understood. The release inagnet 121 is operated in the same lmanner in connection with the switch F that the release magnet 108 is operated in connection with the switch E: The private .magnet 122 is controlled by the private magnet relay 123. The release relay 124 of the secondselector switch F performs the same function in connection with this switch as the release relay -112 performs'. in connection with the rst-selector switch E. In the switch F the relay 123 is so arranged that it deneigizes slowly, the same as the relay 106 of the selector switch E.

The connector switch AH (Fig. 2) is aisc modified formof the connector switch disclosed in United States Letters Patent No.,y

815,176, granted'Marchgl3, 1906, to Keith,

Erickson & Erickson. The connector switch shaft (not shown), like the selectorswitch 1 shaft, carriesithelinewipers 125 and 126 and theI privatewiper 127. The connector switch, is also controlled by the calling sub- -scriber through the medium of a double- Woundline relay 128.l The line relay 12S is provided with the windings 129 and 130. One terminal of the Winding 129 is con nected to the battery lead, while the other terminal ,is connected with the vertical 15 trunk-lineconductor. The Winding130 is connected .with ground and also with the rotary trunk-line conductor. rll`his line relay 128 Adirectly controls the vertical magnet 131. The purpose of the vertical magnet 131 is to `give. the shaft and shaft wipers a vertical motion, and the rotary magnet 132 imparts to the shaft and shaft wipers a rotar or circular motion. The connector switch is alsoprovided with the slow-acting release relay 133, which is the same as the release relav v1211-` ot' the second-selector switch F. The'private magnet relay 131, as usual, controls lthe private magiet 13.5, which latterfcontrols the side switch wipers 136, 137, 13S, 13,9, 13.9a and 140. The backbridge relay 141, comprisingthe windings. 1112 and 143, serves as a means whereby the called subscriber is provided with battery current for talking purposes. As illustra-ted, my connector switch is of the automatic ringing type-ethat is, a signaling of the called subscriber is not dependent upon the calling-subscriber pressing a signaling button when hecalls a line; but as soon as connection is established with the desired line, the interruptor 144 intermittently closes 'an energizing circuit through `the ringer relay 145, whereby the terminals of the ringer 'generator' I are intermittently bridged across thenormal conductors ot the called line. The relay 146 is so arranged that if Va busv lline `is called the connector side switch is locked in second position, and the calling subscriber is given the busy-signal. The means Vwhereby the connector switch may be restored lto normal Vposition is. proi'ided by the usual release magnet 133 which, when the connector switch shaft is .raised one or more steps. is connected-to the battery lead through the normal springs 131a and 1321. By means of the condensers 147 and 1418 the circuitthrcugh the connectoi-.switch is divided into two. sections. The busy-signaling` apparatus J. comprises the 150 of the induction coil 151. The winding 152-is connectedwith the spring 153, and when the relay'll energizes, aswill be Aeitplained, the busy-signaling apparatus is connected "with the connector side switch wiper interruptor 1419 in series .with the windingl 136. The relay 133 of the connector, it will be seen, is similar to the relays 112 and 124: ot' the. selector switches-that is, it is arranged with a secondar)v winding which is short-cirduited when the side switch is in '70 first or second position. thus making the rela)Y slow-acting; but when the side switch passes to third position this short-circuit is removed and the relay then becomes quickacting. It will be seen that it is necessary for the relays 112, 121 and 133 to be Slow-` acting when the side switch is in iirst and second position, but after the side switch passes to third position I find that it is desirable to have these relays quick-acting.

The operation of the system may be more clearly understood trom an explanation of itsoperation in the course ot' establishing a connection. It will be assumed that the sub scriber at substation A wishes to call the subscriber at substation A `to which is allotted the number 2220. To call the number (substation A', Fig. 2) the subscriber at substation A (Fig. 1) removes his receiver' from the switch-hook and operates the calling' device for each digit in the wellknown manner-that is, when the receiver is removed fromV the switch-hook a preliminary impulse provides an energizing circuit for the trip magnet 23 of the line switch C, 95 whereby the line switch C is operated to' seize an idle trunk-line leading to a firstselector switch. The digl is then turned for the first-digit, and upon returning to normal position operates the first-selector swit h to establish connection with an idle trunk-line leading to a second-selector switch. In a similar manner, upon returning to normal 'position torrthe second digit, the dial operates the second-selector switch F to establish connection with an idle trunk-line leading to a connector switch. The impulses delivered by the dial for the Ylast two digits are-directed toward the connector H which operates to place the shaft wipers in tonnection with the contacts corresponding to the desired substation. Thepreliminary impulse for energizing the trip `magnet 23 occurs when'the receiver 2 is removed from the switch-hook 3 and the camarrn 16 permits the spring 17 115 Ito engage the spring 18. thereby removing lthe ringer from across the line and bridging the primary circuit instead. `When the primary circuit is thus bridged across the line,

the energizing circuit formijhe trip magnet 23 120 i is completed and extends from ground Gr (Fig. 3) through the trip magnet 23, throughA the springs 50 and 49, conductor to the rotary line conductor-2O (Fig. 1), through the springs 17 and 18, impulse 125 springs 15 and 14, primary winding 5, transmitter 7 to the vertical line conductor 19, thence -through the conductor 156 (Fig. 3), springs 51 andl 52, through the resistance coil 151 -to Vthe batterv lead 103, thence 130 through battery B to ground G. As soon as the tripv magnet 23 energizes, .the armature 27 is attracted, and the plunger 21 is lib- (and consequently all idle plungers that" erated and thrust into the bank terminal Q by the spring 47, assuming that the plunger 21 is opposite the terminal Q at/.the time. When the plunger 21 engages the bank terminal Q an energizing circuit is established through the motor magnet relay 56, l,which in turn operates-to close an energizing circuit through the'motor magnet 53 of the master switch D. The motor magnet then operates to advance all idle plungers thatare in locking engagement with the shaft 43 opposite the next idle bank terminal-similar.

to the terminal Q. lThe cir-uit through the relay 56 extends romjground G2 through.

thewinding 158 of the. relay-56 to the c ommon .segment 57, thence through the wiper 5-8, through the segment 60, conductor 159,-

73, motor magnet springs 7 0 and 71, through of the motor magnet 53 to the- 103. thence through battery B the windin battery lead togroundl G. The motor magnet 53, upon energizing. attracts its armature 67, Wlierelby the pawl 68 engages the rat het wheel 54, advancing the latter one step. When the armature 67 is attracted against the magnet cores. the springs 70 and 71 dise-ngage, thereby breaking the energizing `circuit through the motor magnet 53 and permit? ting the armature 67 to return to .normal position. The cam 55 being in engagementwith the pin 63 upon the ratchet wheel 54 is operated Ito advance the plunger shaft 43 may be in normal locked position with the shaft43) opposite another terminal similar to the terminal Q, assuming the next suc# ceeding trunk is idle. i wiper arm 58 is carried from 'the contact point 60, which corres-ponds to the terminal yQ, to the contact point 74, which latter corre? sponds to the terminal before which the ad-A vanced idle plungers -a renow resting. -Suppose that nine subscribers have called and that the master switch has thus operated nine steps, carrying the wiper 58 to the last contact point 59. Now` when the motor magnet 53 operates for the next step, when the tenth subscriber calls, the wiper 58 passes back and drops into engagement with Consequently, the

the Contact point 60. If the'tirst trunk is still busy the wiper 58 finds a battery .potential on the contact 60, and an energizing circuit is establ'shed through the differential relay 56-whi.h in turn.. operates to close an n energizing circuit through theinoto'r magnet 53. The vcurrent through the said relay 56 flows from the said Contact 60 thro-ugh the wiper 58 'to the common se'gni'ent 57, and through the Winding 158 ofthe dilferential relay 5,6 to. ground G2. vWhen this relay energizes it operates to close the circuit through the motor magnet 53, and the motor magnet then operates, as vpreviously explained, to rotate the ratchet Wheel 54 one step, and the master switch bank wiper 58 one step also and into engagement with the second segment 74. When thus advanced one step the plunger shaft 43 carries all idle plungers that are in locking engagement with said shaft opposite the first bank terminal, as previously explained. It there should still be a guarding potential at the bank segment A74` the differential lrelay 56 will remain energized,` whereby the energizing circuit through the'motor magnet 53 is again completed when the motor magnetv springs 70 and 71 again engage, and as a re- -Sult the motor magnet 53' is again operated, whereby the plunger shaft 43 and the master switch wiper 58 are advanced another step. This pro ess continues as long as the Wiper 58 continues to find segments with guarding potentials. As soon as an idle segment is found, however, the.. energizing circuit through the relay 56 is broken, at which time the said relay in turn breaks the energizing circuit for the miotorr magnet 53 until the next su'bscriber makes a call. VAt the instant that the plunger 21 enters :the bank terminal Q the following springs are pressed into contact: 35 and 36, 37 and 38` 39 and'40, and

41 and 42.v The engagement of the springs 39 and 40 closes a circuit through the cut-oit -relayf48 extending from groundl Gt through the .springs 40and 39. conductor 160, relay '48 tothe battery-lead 103, thence through V batteryB to ground G.. The said relay, upon energizing, operates-to carry the springs' 49 and 51-outof engagement with the springs A50 .and 52. When these springs disengage the lcoil i154 is 'disconne ted from the vertical ins line conductor 19, and the trip magnet 23 is l disconnected from the rotary line conductor4 20. The engagement- 4ofthe bank springs 39 and 40 also establishes guarding potential by way of the` normal conductor 80 to the.y connector private bank -contacts correspondf ing' to the line `that terminates in the line switch C, to prevent any subscriber `trom calling the said line after the calling subscriberl at substation A removes his receiver preparatory to making a call, as explained.

Also, the closure of connection between the Springs 4l and 42 establishes a guarding potential at the master switch bank contact 60 over they following circuit: from'battery B to the battery lead 103, thence through the winding of thevrelease magnet 21, through the springs 41 and 12, conductor 159 to the said Contact point60. It will be understoodthat the bank terminal Q, being the first bank terminal of the. line switch bank, corre-r sponds to the first segment 60 of the master switch bank O and, therefore to the trunkline, the conductors 75, 76 and 77 of wht-l1 terminate in the irst-sele1-tor switch E. This guarding potential protects the seized trunk conductors 7 5. 76 and 77 from being seized bv other plungers, as already explained. The closure of connection between the springs 35 and 36 extends the calling subscribers vertical line condu' tor 19 to the vertical trunk conductor and the side switch wiper S1 of the first-selector switch E. The closure vof contact between the springs 37 and 38 in a similar,manner extends the subscribers rotary line'conductor 2.0 to the rotary trunk condu tor 76 and to the side switch wiper of the selector E. The subscriber has thus established connection with the next selector switch, which is now operated by the impulses that are delivered when the dial returns to normal position for the first digit. When the subscribers line conductors 19 and 20 are thus extended to the first-'selector switch E an energizing circuit is established through the line relay 101, said circuit extending from ground G5 'through the winding'101 to the contact point 90, side switch wiper 85, trunkcon'duetor\76, through the bank springs 38 and- 375th the rotary line conductor' 20,'through thesprings 17 and 18, impulse springs 15 and 14, primary winding 5, transmitter 7 to the vertical line conductor 19, through the bank springs 35 and 36, trunk conductor 7 5, side switch wiper 84, Contact point 89, through the winding 102 to -the battery lead 103. thence through battery B to ground Gr. The relay 101, upon energizing, operates to place the springs 161 and 162 in contact, whereby an energizing circuit is established through the release relay 112. said circuit extending from ground G6 through the springs 161 and 162, relay 112 to the battery lead 103 thence through battery B to ground G. The release relay 112. upon energizing, operates to carry the spring 163 out of engagement with the spring 161 and into -engagement with' the spring 165. This is the condition of ,the firstselectorswitch E when the subscriber opcrates the dial for the first digit. The first digit being 2, the impulse spring 14 is twice carried out of engagement with the impulse sprirg 15. Y As a result the energizing cir-` cuit through the line relay 101 is broken twice, and the spring 161 comes irto contact with the spring 166 twice. After the two impulses are thus delivered the line relay 101 again energizes and carries the spring 161 into contact with the spring 162. As previously explained, the relay 112 is a slowacting relay-that is, slow to denergize; and when this energizing circuit is momentarily broken during theA vertical impulses just delivered, the said relay does not de energize, but remains in an operated position with the spring 163 in contact with the spring 165. Then when the spring 161 e11- gages the spring 166 two impulses are transmitted to the vertical magnet 105, over a circuit extending from ground G through the springs 161 and 166 to the springs 163 and 165, through the private magnet relay 106, through the winding of the vertical magnet 105, contact point 107, side switch wiper 87 to the battery 'lead 103, thence through battery B to ground G. The impulses 'being delivered, the vertical magnet 85 105 is thereby energized twice, and the shaft wipers are given two vertical steps in the well-known manner. It will be seen that the private magnet relay 106 is included in the energizing circuit of the vertical magnet 105. This relay also energizes, but being a slow-acting Irelay' it energizes on the first impulse and remains so until all the impulses are transmitted. This relay, upon energizing, operates to close the springs 167'- and 168 in contact, whereby an energizing circuit is established through the private magnet l88. This circuit extends from ground G6 through the springs 167 and ,168, private magnet 68 to the battery lead 103, thence through battery B to ground G. The private magnet relay 106 denergizes after the last vertical impulse, since this energizing circuit is no longer maintained after the springs 161 4and166 disengage. Hence, the said relay denergizes, permitting the springs 167 and 16S to disengage, whereby the energizing circuit through the private magnet 88 is in turn broken, which private magnet now denergizes and lpermits the side switch to pass from first to secondposition, permitting'the side switch wipers 86 and 87 to engage the contact points 95 and 96, respectively. The closure of contact between the side switch wiper 87 and the contact 115 point 96 sets up an energizing circuit for the rotary magnet 92 from ground G5 through the interruppter springs 169, through the winding of the rotary magnet 92, con-l tactv point 96. side switch wiper 87 to the 1520 battery lead 103, and through battery B to ground G. 'The said rotary magnet then operates to rotate the shaft wipers 81', 82 and 83 of the selector E into engagement with the first contact of the second level 125 of the selector banks. from whichcontact it is assumed the trunk-line conductors 170, 171 and 172 lead to the second-selector switch Ef If the first trunk-line is busy, however,'and the wipers have to pass over 130 busy trunk-lines, then as soon as the vprivate wiper 83 engages the first private banlrcontact, the private magnet 88 again energizes, locking the side switch in second. position. The energizing circuit for said private magnet extends from the grounded terminal Gr of the battery B Athrough an occupying switch (not shown), through the private Wiper 83, .thence through the conductor 173 to the side switch wiper '86, contact point 95, through the winding ot the private magnet 88 to'the battery lead 103, thence through battery B to ground Gr. The private magnet 88, upon thus becoming energized, locks the side switch wiper 87 in engagement with the contact point 96, Awhereby the rotary mag net 92 will be energized step by step until the wipers are carried beyond the lastflmsy trunk-line. At the instant that the private' wiper leaves the last busy contact point the energizing circuit through the private mag-- net 88 is destroyed, and as a result the sclector'side switch passes to third position. If, however, there are no busy trunk-lines, the private magnet 88 releases the side switch to third position as soon as the wipers are carried into engagement with the first trunkline. -As soon the side switch passes to third position, as stated, the subscriber-s line conductors 19 and 20 are extended to the conductors 170 and 171 which, in this case, it is assumed, lead to the second-selector switch F. The extending of the line occurs, of course, as soon as the side switch wipers 8 1 and Sti-engage the contact points 97 and 98, respectively. When the subscrihers lines are thus extended to the selector switch F an energizing circuit is established through the line relay 114 in the same .manner in Which the energizing circuit was established through the line'relay 101 of the selector E when the subscribers line conductors 19 and 20 were extended through the line switch bank to the trunk conductors 75 and 76. The

.relay 114, upon energizing, operates to shift the spring 17 t from thel spring 175 to the spring 176. When the springs 174c and 176 engage, an energizing circuit is established throughA the release`relay 121. This circuit extends from ground G7 through the springs 171r and 176, through the relay 121 tothe battery lead 103. thence through battery B te ground G. The relay 1211, upon energizing, operates to shit't the spring 177 from the spring 178 tothe spring 17 9, and the springs 180 and 181y are also closed in contact. This operation ot the second-selector switch F occurs at the instant that the side switch wipers 84 and 85 of the selector switch E passte third position and extend. the subscribers line `conductors 19 and 20 to the second-selector switch F. Therefore, when the second-selector switch thus operates, a guarding potential is established at the private wiper 83 forprotecting the seized trunkvertical magnet 120 remainsopen. the relay 123 en ergizes, the springs 186 and line-conductors 170 and 171 against seizure passes to third position, a new energizing circuit is established through the release relay 112. Tins energizing circuit extends .from ground G8 at the'selector switch F throug'i the springs 181 and '180, conductor 172, shaftwiper 83, conductor 173, through the vside switch wiper 86, contact point 99, to the battery lead 103, thence through battery B to ground G. The relay 112 thus remains in an operated position, with the spring 163 in engagement with the spring 165, lbut the line relay.101 returns to normal posi-- tion when the side switch wipers 81 and 85 engage the contact points 97 and 98, respectively. The energizing circuit through the line relay 1141 extends from ground G9 through the winding 116 tothe sideV switch wiper 118, thence through the conductor 171, conductor 7 6 and line conductor 20 through the primary circuit of 4the substation, through the vertical `line conductor 19,' thence through the trunk conductor'75, conductor 170, side switch wiper'117, through the winding 115 of the relay 114 to the bat.- tery lead 103, thence through battery Bv to ground G. lVhen the dial-returns to normal position for the second digit 2 this circuit 100 through the line relay 114: is interrupted twice, when the impulse spring 14 is carried out of engagement with the spring 15 bythe impulse teeth on the Wheel 10. The circuit being interrupted twice, the said relay 105 1111 momentarily denergizes, thus permitting the spring 1711' to engage the spring 175, whereby an energizing circuit is com-y pleted through the Avertical magnet 120,

said lcircuit extending from. ground G 110 to the springs 171 and 175,-springs 177 and 179, through the winding of the private magnet relay 123, through the winding of the vertical magnet 120, contact point 184,

side switch wiper 185 to the battery lead 115 103, and through batterv B to ground G. The private magnet relay 123 being included in this circuit. lenergizes, and since it is a slow-actingrelav it remains in an operated prsition until the last vertical im- 120 pulse is delivered. and the relay 111 remains energized lwith the spring 174 in contact with the spring 176, whereby the circuit through the private magnet relay and the 187 aie pressed into contact. thereby causing an energizing current to flow through the private magnet 122. the circuit extending from ground @f7-through the springs 130 When l25 187 and 186, through the winding of the private magnet 122l to the battery lead 103, thence through battery B to ground G. When the relay 123 denergizes and breaks the energizing circuit through the private magnet 122, the private magnet denergizes and permits the side switch to pass 'from iirst to` second. position. When the side switch wiper 185 passes to second position and into engagement withthe contact point 188, an venergizing circuit is established through the rotary magnet 119, which now operates (as explained in connection with the rotary magnet 92 of the selector switch E) to seect an idle trunk-line leading to the connector switch. After the switch comes to rest with the side switch' in third position, the shaft wipers 189, 190 and 191 are in engagement with the trunk conductors 192, 193 and 194, respectively.A which lead to the connector switch H (Fig. 2). At the instant that the side switch wipers 117 and 118 pass to third` position, into engagement ywith the contact points 195 and 196, the subscribers line conductors are extended to the connector switch H, and an energizingv circuit is established through the line relay 128. in the same manner in which the energizing circuit was established vthrcugh the 'line relay 114 of the selector switch F whenl the side switch wipers of the first-selector passed to third position. The energizing circuit through the line relay 128 extends from ground G10 through the winding 130. trunk conductors 193, 171

and 76 to the lineconductor 20. thence through the substation to the line conductor 19, trunk conductors 75, 170 and 192, thence through the winding 129 to the battery lead 103, and through battery B to ground G. The line relav 128. upon energizing, operates to Hshift the spring 196 from the spring 197 to the spring 198. whereby an energizing circuit is lestablished through the release relay 133, extending from ground G through the springs 196 and 198, relay 133,

to -the battery lead 103, thence through battery B to ground G. lVhen the relay 133 energizes. the spring 199 is shifted out of contact with the spring 200 and into con-l tact with'the spring 201, and thespring 202 is shifted into engagement with the spring 203. This primary operation of the connector relays 128 and 133Aoccurs at the instant that the side switch wipers 117 and 118 of the selector F pass-to third position and extend the subscribers line conductors to the connector H. The engagement of the springs 203 and 202 establishes a guarding potential for protecting the-trunk-line conductors 192, 193. and 194 against seizure. by another line and second-selector. This potential extends from ground Gm to the side vertical energizing circ'uit is established through the release relay 124, said circuit extending from ground Gr11a at the connector switch to the conductor 194, through` the shaft Wiper 191, side switch wiper 204, conductor 205, through the release relay 124 to the battery lead 103, thence through battery B to ground G. Also, this same guarding potential established at the contact engaged by the private shaft'wiper'191 is extended tothe private bank contact engaged by the shaft wiper 83 of the First-selector E, when the side switch of the second-selector F passes to third position. The path over which this potential extends is as follows: from ground Gr11a at the connector switch H (Fig. 2) to the side switch wiper 139, springs 202 and 203, conductor 194, shaft wiper 191, side switch wiper 204. conductor 205, contact point 206. side switch wiper 183, springs 181 and 180, conductor 172 to the bank contact engaged by the private wiper 83 of the selector switch E. The operation of the dial for the last two 1digits affects the connector switch. and when the dial is operated tor the third digit 2 the impulse spring 14 is twice carried out of engagement with the spring 15, thereby momentarily denergizing the line relav 128 twice, whereby the spring 196 twice engages the spring 197, thus sending two impulses to the vertical magnet 131 from ground G through the springs 196 and 197. springs 199 and 201, through the vertical magnet `131,. contact point 207. side switch wiper 140. private magnet relav 134 to the battery lead 103. thence through battery B to ground G. The private magnet relay 134 energizes "when the first impulse is delivered, and since the saidvrelay is slow-acting it remains in an operated position until all the vertical impulses are sent. The vertical magnet, upon being energized. operates one step at a time to carry the shaft wipers 125, 126 and 127 two stepsto a point opposite the second level. The relav 134, upon energizing. shifts the spring 209 ont of engagement with the spring 210 and into engagement with the spring 211; also, the spring 212 is shifted out of engagement with the spring 211. When the springs 209 and 211 engage. an energizing circuit is established through the private magnet 135 from ground ,(113 through the springs 211 and 209, private magnet 135 to the battery lead 103, thence through battery B to ground G. The relav 134 being aV slow-acting relay remains in an operated position while the vertical impulsesare being sent; but

after all the impulses are delivered, and the tion, the circuit through the relay 134 becomes broken, thus permitting the springs 212 and 209 to return to normal position. When the springs 209 and 211 disengage, the circuit through 'the private magnet 135 becomes broken, whereby the said magnet de-` said springs 196 and 197 and through the] springs 199 and 201, locking-relay springs 211a and 212, through the rotary magnet 1 32hto the contact point 213, thence through the side switch wiper 140, and through the private magnet relay 134 to the battery lead 103, thence through battery B to ground G. Again the private 'magnet relay energizes, as in the previous case, remaining-so until all the impulses are transmitted, thereby retaining the private magnet also energized. The rotary magnet 132 then operates to rotate the shaft wipers into engagement with thedesired line #2220. If this line is busy at the time, the connector side switch will be locked in secondposition, in a manner to be described, and the calling'subscriber is given a busy-signal, thus making it -impossible to extend the calling line into connection with the called line. Before describing the results that follow when the connector finds a busy line, the description of how a 4connection is established will be completed.`

As soon as the line relay 12,8 ceases to operate for the last digit, the private magnet relay 134 de'e'nergizes, as heretofore eX- plained, permitting, in this instance, the sidevswitch ,to pass to third position. The result is that the side switch wipers 136, 137, 138. 139. 139a and 140 engage the contact points 214. 215, 216, 217, 217a and 218, respectively. When the side switch wiper 138 engages the contact point 216 a guarding potential is completed at the private wiper 127 Y for protecting thev seized line from outside interference while the connection` is established.. This guarding potential extends from ground (i14 to the Contact point 216, thence by way of the side switch wiper 138, locking relay springs 219 and 220 to the private wiper127. Not only does this guarding potential prevent other connectors from arriving on the same line over multi-` ples of the normal conductors 221, 222 and `223,'but it also provides means for energizing the cut-ofi' relay 224 of the line switch C', whereby said switch C is prevented from operating when the called subscriber removes his vreceiver 225 from the switch-hook 226.' It will also be seen that when the side switch passes to third position the trunk-release conductor 194 that runs between the second-selector and the connector is provided with guarding potential from ground G11 through the line relay springs 19(3.and 198, contact point 217, side switch wiper 139, release relay springs 202 and 203 to the 'trunk conductor 194. However, while the side switch is in lfirst and second 1iosition a guarding potential for this trunk 194 is also provided from ground G11, but through the side switch wiper 139 direct. The reason -for this is that the guarding potential from ground G11 is 1nterrupted while Vthe line relay 128 is operating, and there is some liability of some other selector similar to the-selector F stopping on the same trunk-line. After the side switch passes to third position, however, there is no such liability, and the potential is provided from ground G11 through the line relay springs, as stated. Of course, when the side switch wipers 136 and 13.7 engage their third-position contact points 214 and 215, the calling subscribers line is placed in connection with the called subscribers line over the heavy conductors shown, passing through the ringer relay springs 227 and 228 on lone side, and and 230 on the other side. As soon as connection is thus established, the ringer relay 145 is energized over the circuit established when the side switch wiper 140,engages the contact point .218, the energizing current flowing frein ground G15 through the interrupter 144,through the back-bridge relay springs 231 and ringer relay 145, conductor 233, contact point 218, side switch wiper 140, private magnet relay 134 to the battery lead 103` thence through battery B to ground Gr. It will beseen that as the interrupter 144 revolves, the energizing cir- -terininals of the ringer generator I. As a result.` ringing current is sent overthe called line for energizing the bell'234 while the springs 237 and 246 are in contact. How ever, as soon as the called subscriber' answers, the back-bridge relay 141 is energized by a tlow of current from ground G14, contact point 210. side switch Wiper 13.8. wind ing 143 of the back-bridge relay 141` conductor ringer relay springs 229 and 230. side switch 4wiper 137, contact point 215. rotary line wiper 126` rotary normal conductor 222, rotary line conductor 236, switch-hook springs 237 and 238, impulse springs 239 and 240, transmitter 241, verti- 1 cal line conductor 242, vertical normal conductor 221, vertical linewiper125, contactpoint 214, side switch wiper 136, ringer re- 'lay springs 228` and 227, conductor 243,

winding 14201 the .back-bridge relay 141, thence to the battery lead` 103. and through battery B to ground G. When the back- 'bridge relay 141 is energized, the energizing r After the subscribers are through talking,

if the calling subscriber hangs up his receiver he opens up the line circuit at a point between the springs 17 and 18. thereby initiating the release of all'of the switches. Thisrelease is brought about as follows: At the instant that the circuit is broken between the said springs 17 and 18 the double-wound line relay -128 and release relay 133 of the connector H denergize. At the instant that the relay 133 and the line relay 128 deenergize the energizing circuit for the release magnet 133a'is closed at apoint between the springs 199 and 200, and at. another` point between the springs 196 and 197. 'A How of current is. thereforeset up from ground G11 through the springs 196 and 197, through the springs 199 and 200 to the release magnet 133, thence through said magnet t0 the ott-normal spring 132e, to the contact point 131a and to 'the battery lead 103, thence through battery B to ground G.

The release magnet 'instantly releases, the

connector switch shaft and side switch, thereby breaking the energizing circuit through the back-bridge relay 141. if the calledV subscriber. has not inthe meantime restored his receiver, and also the energizing circuit throughV the bridge-cut-oif relay 224 of the called line switch C. As soon as the connector switch shaft reaches its lowest position it breaks the circuit of the -release magnet 133a by separating the oliiormal spring 132a from the contact point 131e, at which instant the release magnet ot the connector is also restored. explained` the relay 133 is quick-acting when the side switch is Ain third position; hence, the contact between the springs 199 and 200 is made at 'the saine time the contact is made between the springs 196 and 197. Prior `to this arrangement the relay 133 was slow-acting` during the release, and

lsome little timeelapsed before the relay 133 returned to normal position and closedthe circuit for tlierelease magnet. With my As previously new arrangement the release circuit is established immediately whenthe linerelay denergizes. The operation of the line relay 128 and of the relay 133 not only causes the release of 'the connector, as described, but also the release of 4the preceding switches, because the ground connection from ground G11 to the trunk-release conductor 194 is interrupted by. both of these relays'. Since the release relays 124 and 112 are-dependent upon that ground for their energized condition, as already explained, it followsl that they will fall back, with the following results: As soon as the release relay 124 of thesecon'd-selector F denergizes, thespring 177 falls back into normal engagement with the spring 178, thereby closing an energizingl circuit for the release magnet. 121 from ground G7 through the springs 174 and 175,- through the springs 177 and 178 to the release magnet 121, thence to the contact point 249` olf-normal spring 250 to the battery lead 103, thence through battery B to ground G. As soon as the release magnet 121 energizes, the second-selectorside switchand switch .shaft are restored, which switch shaft,upon reaching its lowest position, opens the release circuit at a point between the oH-normal spring 250 and the contact point 249, whereby the release magnet 121 is restored also. When the release relay 112 of the selector E deei'iergizes` the springs -163 and 164 are brought into'coiitact and as a result the energizing circuit for the release magnet 10S is closed. The energizing current for this release magnet 108 then ,flows from ground G8 through the springs. 161 and 166` through the said springs 163 and 164 to the release magnet 10S, thence through said magnet to the contact point 110. off-normal spring 111 to the battery lead 103. thence through battery B to ground G. The release magnet,

upon energizing, restores the first-selector' opens the energizing circuit for the release magnet 108 at a point between the olf-normal spring 111 and the contact point 110. Furthermore, when the release Vmagnet 108 energizes and closes the springs 251 and 252 in Contact, an energizing circuit is established'throiieh the release magnet 24 of the line switch C. This circuit extends from ground G4a through the springs 251 and 252. conductor 77 to the bank springs 42 and 41. thence through the releasemagnet 24 of the line switch C tothe battery lead 103, and through battery B to ground G. It will be seen that the release magnet will then energize and. as previously explained, causethe trip armature 27 to fall over the plunger arm 22, whereby the members 32 and 33 engage. lease magnet denergizes and separates the (See Fig. 3.) As the re-.

springs 251 and 252 the release circuit is broken` which permits the release magnet 24 of the line switch C to denergize, thereby withdrawing the plunger 21 from the bank terminal Q.

thus preventing any other action from the trunk After the switches are thus restored the calling subscriber can then proceed to make another call.

Returning'now to that stage of the call Where the calling subscriber was operating the connector switch in'ac"ordance with the last digit 0, it will be explained what takes place in the event that the desired vline is Acontacts of the line switch as shown in Fig.

1, thence to the private bank contact of the connector switch. In a similar manner the line switch C protects the calling line A when the bank springs 39 and 40 come into Contact from ground G, from which latter connection is established through the said banksprings to the private no rmal conductor 80. Therefore. when the subscriber sends in the last impulse,the private wiper 127 is carried .onto the grounded contact; and when the slow-acting relay 1.34 of the connector denergzes, instead of the side switch tripping to third position, as in the case where the line is not busy. it is lo'ked and the calling SubS^riber is then given a busy-signal. The method bv which this side switch is locked is as follows: The slowactingrelay springs 209, 210 xand 211 are so arranged that as the relay 134 denergives. the spring 209 engages the spring 210 before it leaves the spring 211` and in this way the private magnet 133 is prevented from deinergizing. because the spring 210 is connected with the private wiper 127 at the time over the following circuit: from thc private wiper 127 to the locking relay spring 220, then'e to the spring 219 and through the winding 143 of the back-bridge relay 141 to the talking line conductor 235, thence through the rrgerrelay springs 229 and 230 to the side switch wiper 137, contact point 253, (the side switch being in second position) to the slow-acting relay spring 210. Therefore, when thevspring 209 engages Ithe spring 210 the privatemagnet 135 is not denergized, since the energizing cir- As a result the bank springs 41 and 42, aswell as the other bank springs of the line switch C, are separated,

cuit is maintained from the private Wiper '127 to the said spring 210, as described,

thence through the spring 209, and through the private magnet 135 to the battery lead 103, thence through battery B to ground G. The private magnet therefore remains energized, retainin the side switch in second position. It wlll-be seen that at the same time the bark-bridge relay 141 energizes in series with the private magnet 134 over this circuit from the'private wiper 127. Therefore, the back-bridge relay 141, upon energizing. presses the springs 254 and 255 into contact thereby energizing the locking relay 146, over the following circuit: from ground G13 through the sloW-ating relay springs 211 and 212, through the private magnet springs 256 and 257, vthrough the said relay 146, and through the back-bridge relay springs 255 and 254 to the battery lead 103, thence through battery B to ground Gf ltnvill be seen that when the relay 146 energizes, the connection between the rotary magnet132 and the line relayv springs is broken at a point between the springs 211@ and 2122 The obje"t of this arrangement is to prevent the calling subscriber from further rotating the connector switch'if he 'should attempt to operate his dial 'while receiving the busy-signal-that is, while the connector swit'h is4 locked in second position. It l'will also be seen that when the relay 146 energizes, the circuit for maintainingtheprivate magnet 135 energized is shifted from the private Wiper 127 to the spring 258, which latter is lconnected to ground G19. The object of this arrangement is to prevent the side switch from unlocking and passing to third position if the switch that is maintaining the called line busy should be released while the calling subs'riber A (Fig. 1) is receiving the busysignal. It will be evident that if the ground G1 were not substituted for the ground at. the private wiper 127. the private magnetV 135 would denergize if'the switch that is 'supplying ground at the-private wiper 127 should release. This would, of course, be undesirable. It willalso be seen that. the relay 146, upon energizing, closes 'the springs 259 and 153 in contact. thereby establishing the busy circuit as follows: from the secondary winding of the busy coil 151 through the springs 153 andv 259 to the second-positign side switch contact point 260, side switch wiper 136, ringer relay springs 228 and 227, through the condenser 147. through'the substation Ato the rotary side of the line, then over said rotary-sideback to the connevtor H, andthrough the winding 130 of the line relay 128 to ground G1", thence to the interrupter ground G20. through the interrupter 149 to the primary winding ofthe busy coil 151 back to the sec-y 'scriber receives the busy-signal he understands th'at`the .line is busy and hangs up his rereiver'. The line' circuit is opened, as already explained, with the result-that the relays 128 and 133 of the `connector H de- -encrgize, causing the release lof the connector and 'all' otherrswitches, as heretofore eX- plained. It will, of course, be seen that as 4soon as the side switch is restored the ener-- gizlng circuit for the back-,bridge relay 141 .that includes thewinding 143 thereof, and

-for the private magnet 135, is broken, when the side switch wiper'1'37 leaves the contact point 25.3. Now, since the'energizing circuit of the lo king relay 14S-is controlled by the back-bridge relay 141, the saidv locking relay -is `alsodenergiz'ed, andthe connector switch is y' left in a normal condition.

pFrom the foregoing it will be seen that with my new `release arrangement' and after a connection has been fully established the release'circuit for thejrelease magnets lof the various switcheslis' establishedy as soon" as the callingsubscrlber restores his receiver to the switch-hook and clenergizes the line relay. Prior -to Vthis arrangement the release circuit in certain two-wire systems was not establisheduntila' slow-acting relay de'e'nergized.

It will vbe seen that'I provide an autox matic trunking system having arelease relay means adapted in part at least to remain slow-acting until the called line lis found, and provided with means whereby such re lay means'is rendered quick-acting .in its entirety upon thev completion of the call,

thus enabling the said relay means .to pre` venta premature release during the progress of the call, withoutrendering the release `slow or sluggish-when the time comes for disconnecting vthe two lines-that is to say, o

when the calling subscriber hangs up his receiver. Each release relay is provided with means, `suchias a coil closed upon itself, for rendering-it slow-acting while there is danger of its `being {denergized-.durng the progress of .the call; andvis also provided with means, such as a switch in the closed circuit of said coil or winding, forl making it quick-acting-that 1s, quick todeener-v 'gizeas soon as there 1s no longer any danger of its being denergized by the brief breakingvor opening of the line circu`t at the calling substation, during the progress of the call. In this Way, one relay after the other in succession is rendered quickacting, in the manner specified, and as soon as the called lineis found, and the side switch of the connector has passed to third position, then the lastslowfacting release relay is made quick-acting, so that the entire slow acting relay means has thus become, a 'oluickl acting relay means, the transition from slow-1 acting to quick-acting capacity on thepart of the release having been accomplished automatically and progressively during the action' of extending connection from the calling line to the called line. Upon the release, however, which may be initiated by yquick-acting lrelay means, so that the (le-- 4ener'gizir'ig will be instantaneous and the release practically simultaneous with the hangingup of the receiver at the subscribers station.

It will be, .observed that` the system' includes switches having vertical motion for seleftlng groups, and lrotary motion .for connecting with a line in a selected group, as

both the selectors and the connectors have 'vertical and' rotary motion` for this purpose.

The selection of a trunk in a group selected by a calling subscriber ispurely automatic, as :the selector automatically picks out or selects the first idle'trunk. The selection of the called line is, however, under the control of the'calling subscriber, so that by means of the connector the calling subscriber first uses' the vertical motion for selecting V the desired group, and-then uses the rotary motion for selecting and connecting with the particular line ofthe called subscriber. What I claim as my invention is 1. In. a telephone system, ltheco'mbination of switches having vertical and rotary motion' to extend connection tothe called line, a release-relay means therefor, means 'for 'making said relay means slow-acting to prevent premature release before the called line is found,-.and vmeans for making said relay 4means quick-acting for releasing purposes.

`2. In a vtelephone system, an automatic switch, means for controlling the release of said. switch, said means including a relay, and means for `making said relay slow-acting during the call and quiclcacting after the call. p V

3. Ina telephone system, a series of release-relays, switching means to vbe released .thereby` means for normally rendering sald relays slow-acting, and means progressively and successively rendering said relays quickacting during the progress of the call.

4. In a telephone system, a switch, arelease relay therefor` a trunk, a circuitl for maintaining the said relay energizedwhile the switch is" searching for the trunk, an-

. other circuit' over the trunk for energizing the said relay after the trunk is found and seized, means for makin the relay slowacting during the search or the trunk, and means for making said relay quick-acting after the trunk isfseized.

5.- In a telephone system, the combination of subscribers lines free from operating grounds at the substations thereof, whereby callsare transmitted from the substations over both sides of the line in series, an automatic switch, means for controlling the -release of said switch, said means including a relay, and means for making said relay slowacting during the call and quick-acting after the call.

6. lIn a telephone system, the combination of' subscribers lines free from operating grounds at the substations thereof, whereby calls are transmitted from the substations over both sides of the-line in series, a series `of release" relays, switching means to be released thereby, means for normally rendering said relays slow-acting,and means progressively and -successively rendering said relays quick-acting during the progress of the call.

' 7. In a. telephone system, the combination of subscribers lines free from operating grounds at the substations thereof, whereby calls are transmitted 4from the substations over both sides of the line in series, a switch, a release relay therefor, a. trunk, a circuit for maintaining the said relay energized while the switch is searching fon the trunk, another circuit over the trunk for energizingthel said relay after the trunk is found and seized, means for making the relay slowacting during the search for thetrunk, and means for making said relay quick-acting after theJtrunk is seized.

8. Ina telephone system, the combination of an automaticswitch, means for controlling the release of said switch, said means including a relay, means ,for making said relay slow-acting during the calland quickactingafter the call, and means for initiating the release by opening the line at the callingl substation. A j

9. In a telephone system, the combination of a series of release relays, switching means to be released thereby, means for normally rendering 'said relays slow-acting, means progressively and successively rendering said relays quick-acting during the progress of the call, and means for initiatingthe release by opening the lineat the calling-substation.'

10. In a telephone system, the combination of a switch,1 a release relay therefor, a

trunk, a circuit for maintaining the said relay energized while the-switch is searching for the trunk, another circuit over the trunk for energizing the said relay after the trunk is found and seized, means for making the relay slow-acting during the search for the trunk. means for making said relay quickyacting after the trunk is seized, andmeans for initiating the release by opening the line at the calling substation.

- 11. In a telephone system having metallic ,telephone lines, an automatic switch, means for controlling the release of said switch,

said means including' a relay, means for making' said relay slow-acting during 4the call and quick-acting after the call, and a common battery for supplying current over the metallic circuits for calling and talking purposes.

12. In a telephone system having metallic telephone lines, a series of release relays, switching means to be -released thereby, means for normallyl rendering said relays slow-acting, means progressively and succesover the trunk for energizing the said relay after the trunk is found and seized, means for making the relay slow-acting during the search for the trunk, means for making said relay quick-acting after the trunk is seized, and a common battery for'supplying current over the metalliccircuits for calling and talking purposes.

I14. In a subscriber-operated telephone system, an autom-atie switch, means for controlling the release of said switch, said means including a relay, means for making said relay slow-acting during the call and quickacting after the call, and eallinginechanism requiring a separate manual. operation thereof for each digit 0f the called` number, adapted to transmit current for one digit and then come to rest before manual operation for the nextydigit.

- 15. In a subscriber-operated telephone s ystem, a .series of release relays, switching means to be released thereby, means for normally rendering said.l relays slow-acting, means progressively and successively rendering, said relays quick-acting during the progress of the call, and calli-ng mechanism requiring a separate manual operation there- :of for each'digit of the called number,

adapted t0 transmit current for one digit and then come to" rest before manual `operation for the next digit'.l

16. -In a subscriber-operated telephone sysn tem, av switch, a release relay therefor, a trunk, acircuit for maintaining the said relay .energized while thefswitch is searching for the trunk, another circuitover the trunk for energizing the said relay after the trunk is found and seized, means for making the relay slow-acting during the Search for the trunk, means for making said relay quickacting after 'the trunk is seized, and calling A which the trunks are in groups, means for selecting a group, means for automatically selecting an idle trunkin a selected group, and a release-relay means slow-actingduring the call and quick-acting after thecall, said automatic means released thereby.

/ 123.l In a telephone trunkingv system in which thet'runks are in groups, means for selecting a group, means for automatically selecting 'an idle trunk in a selected group, a series of release relays, saidautomatic means released thereby, means for normally rendering: said relays slow-acting, and means progressively and successively rendering said relays quick-acting during the progress of the call. y

19; In a telephone trunking system in which thetrunks are in groups, means for selecting a group, and for then automatically selecting an idle trunk in'a selected group, said means including a switch, a release relay therefor, a trunk, a circuit for maintaining the said relay energized while the switch is searching for the trunk, anothercircuit over the trunk for energizing the said relay after the 'trunk is found and seized, means for making the relay slow-acting `during the search for the trunk, and means for making said relay quick-acting after the trunk is seized.

20. In a telephone trunking system in Which the trunks are in groups, means for Aselecting a group, means for automatically selecting an idle trunkina selected group, a release relay, said automatic means released thereby, a closed winding or coil thereon for making the same slow-acting to pre vent premature release, and means for opening said' Winding or coil-to make the said relay quickacting for release purposes.

21. In a telephone trunking system, trunks 4divided into groups, automatic switches havlng motion 1n one plane to select groups and' motlon 1n a plane at right angles thereto t0 Y find a trunk in a selected group to extend connectlon .to the ,called line, release relays for said switches, means for making said relays slow-acting to prevent premature re lease, and means for making said relays quick-acting for release purposes.

22. In a telephonef system, an automatic switch, automatic electrically controlled means for controlling the release of said switch, said means including arelay, and means for making said relay slow-acting dulil-ing the 'call and quick-acting after the ca 23. In a telephone system, a series of release relays, switching means to be released thereby, electromagnetic means for normally rendering said relays slow-acting, and automatic electrically controlled means progressively and Vsuccessively rendering said relays quick-acting during the progress of the call.

24. In a telephone system, a switch, a release relay therefor, a trunk, a circuit for maintaining the said relay energized while the switch'is searching for the trunk, another circuit over the trunk for energizing the said relay after the trunkis found and seized, electromagnetic means for making the relay slow-acting during the search for the trunk, and automatic lelectricall controlled means for making said relay quick-acting after the trunk is seized.

25. In a telephone system, the combination of subscribers lines free from operating grounds at the substations thereof, whereby calls are transmitted from thesubstations over both-sides of the line in series, an automatic switch, automatic electrically controlled means for controlling the release of said switch, said means including a relay7 and means for making said relay slow-acting dulil'ing the cal-l and quick-acting after the ca 26. In ay telephone system, the combination of a series of release relays, switching means comprising a progressivelyl movable element to be released thereby, electromagnetically controlled means for normally rendering-said relays slow-acting, automatic electrically controlled means progressively andsuccessively rendering said relays quick- Copies of this patent may be obtained for five cents each. by addressing the Commissioner of Patent Washington, D. C.

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