US1310226A - williams - Google Patents

Description

& K WIUJAMS,Jm

CALL DISTRIBUTING SYSTEM. APPLICATION FILED JULY 14,1917.

1 ,3 l Q,226, Putmted July 15, 1919.

4 SHEETS-SHEET 1.

S. B. WILLIAMS, In.

CALL DISTRIBUTING SYSTEM.

I APPLICATION FILED IULY I4. I917. 1510226. Patent-ed July 15, 1919.

' 4 SHEETS-SHEET 2.

S. B. WILLIAMS, IR. CALL DISTRIBUTING SYSTEM.

APPLICATION men JULY 14. 19:1.

1 3 1 @226, Patented July 15, 1919.

4 SHEETS-SHEET 3.

S. B. WILLIAIVIS III.

CALL DISTRIBUTING SYSTEM.

APPLICATION FILED JULY 14. I927.

MK I M MI W 9 '0 Em mm 1W 0 um f M H G8 Q IE4 V n m h R Sdmue/ 5. IVMI/fi STATEfi PATW @Ftfi.

SAMUEL B. WILLIAMS, JR, 0F BROOKLYN, NEW YORK, ASSIGNOE TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A. CORPORATION OF NEW YORK.

CALL-DISTRIBUTING- SYSTEM;

Specification of Letters Patent. I Patntedt July 5, 11919.,

Application filed July 14, 1917. Serial Ito. 180,633.

To all whom it may concern:

Be it known that I, SAMUEL B. WILLIAMS,-

J r., a citizen of the United States, residing at Brooklyn, in the county of Kings and State of New York, have invented certain the operators positions that are available.

for receiving them. In complex systems of this character, abnormal conditions sometimes arise that thnd to prevent the proper and prompt extending of the circuits of calling lines to the operators positions. It is the principal object of this invention to provide an organization in which such abnormal conditions, when they arise, will be taken care of and prevented from interfering with the proper operation of the system.

Generally stated, the present system provides a plurality of operators positions each equipped with a number of plug-terminated connecting circuits for completing connection with called subscribers lines. The connection between these connecting circuits and the calling subscribers lines is effected necting circuit at that position. The selec-' .tion of an available operators position is controlled by operators selecting apparatus common to all of the finder circuits and all of the operators positions.

In the normal operation of the system the potential which identifies any of the lines as a calling line is automatically withdrawn when the finder circuit makes connection with that line. If through any fault, of the apparatus that potential is not withdrawn, the extension of the line to an operators position may give rise to diiiiculties. One of the objects of the present invention is to prevent the line under such conditions from being extended. Another object is to make the disconnection of the finder circuit from the calling line subject to the return of the connecting circuit to its normal condition so that the finder circuitmay be held and identified, or a characteristic signal given, in case it is not operating properly. Another object of the invention is to provide means for preventing the finder circuit from pro-,

of the invention is illustrated in the accompanying diagrammatic drawing in which 7 Figure 1 shows two groups of lines with two line finder switches formaking connection therewith, together with the associated circuits and apparatus through the medium of which the lines control the switches; Fig. 2 shows one finder circuit complete, and enough of two other finder circuits to illustrate the relationship between them; Fig. 3 shows two cord selector switches of one frame with their associated selection controlling apparatus and circuits, together with similarapparatus and circuits for the cord selector switches (not shown) ofanother frame and Fig. 4 shows the position apparatus and one of the connecting cord circuits of one operators position and indicates the position apparatus and a connecting cord circuit of another position; also one of the called lines with which the cord circuit may be connected. The figures taken together, and arranged side by side in the order indicated by the lines that extend to the margins of the sheets, illustrate as much of a complete organization as is necessary to may be lines of the same'sort, similarly equipped and located at the same exchange; or the lines may be located at different offices. In the present instance, the called line shown in Fig. 4 is indicated as being provided with connectionsby means of which it may have control over finder switch'mechanism in the manner illustrated in connection with the lines of Fig. 1. Each group of lines, LG and LG, has associated with it certain group apparatus consisting of tworelays l9 and 2 1, a common protective relay 250, and a timing sequence switch 100. There is also provided apparatus common to all'of the line groups, comprising the relays 22, 23 and 33. a

The groups of lines have access to. groups of connecting circuits through the medium of finder circuits F, F, and F which terminate upon the brushes of pairs of finder switches of which two sets, LF and GS and LF and OS, are shown. Each of the groups of connecting circuits is associated with a particular operators position, of which the apparatus of one is shown at O and the apparatus of the other is partially shown at O. In the particular system illustrated, it is the practice to provide each operators position with twenty-five connectin circuits extending to multipled groups 0 terminals upon the cord selector switches, and to give the brushes of each cord selector switch access to the terminals of twenty such groups of connecting circuits. But one of the connecting circuits is shown complete, the otherconnectlng circuits in the associated group and in the other groups being similarly organized and connected. Multiple connections of the connecting circuit with the terminals of the cord selector switches are shown. in the case of the connecting circuit that is completely illustrated; and in like manner multiple connections of the telephone line with the terminals of the line finder switches are shown I in the case of the line that extends from necting circuits and their corresponding operators positions. This is indicated in Fig. 3. Each of the groups of cord selector switches has associated with it certain selection controlling apparatus, that associated with the cord selector switches shown in Fig. 3 appearing under the caption Frame 2, and that associated with the cord selector switchesof the other group that is not shown appearing under the caption Frame 1. The selection controlling apparatus for each frame or group of cord selector switches comprises a set of relays 77, 93 and 94: for each operators group, CG, CG, to which the cord selector has access, and a group of relays 52, 5 1, 55, 61, 63 and 254 common to all of the first mentioned groups.

As the line finder switches LF and LF, and the cord selector switches GS and CS" in themselves are not novel, they are shown merely diagrammatically. These switches may be substantially like the switch illustrated and described in the patent to James L. McQuarrie, No. 1,177,044, issued March 28, 1916. The line finder and cord selector switches are alike in all substantial 'respects. Each comprises a longitudinally movable shaft 1 carrying as many sets of brushes 2 as there are groups of stationary terminals to be engaged. To move theshaft up, an extension at the lower end of the shaft is brought into engagement with the constantly rotating power member 3 by means of an idler wheel operated by the updrive magnet 32; and to move the shaft down, the'extension is brought into engagement with the power member 4 by means of an idler wheel operated by the down-drive switch shafts 1 and carries as many tripping yokes 7 as there are finder switches in the group. The trip rod, in rotating, brings all of its tripping yokes 7 into position to operate the brush controlling cams 5 of the corresponding sets'of brushes on all of the switches, so that whichever of the finder switches is caused to move up, has that set of brushes tripped that corresponds with the particular trip magnet 16, 17, that is 'at the time energized. When the finder switch that has been in use is returned. to its normal positlon, any of the associated controlling cams 5 that has been tripped is engaged and rotated in a reverse rection to separate its switch springs again and thus renary commutator segments and a set of mov-' able brushes carried at the top of the switch shaft 1 and cooperating with the stationary segments. This commutator serves to makeand break a number of controlllng ClI'CllltS' in the various stages of the upward movement of the switch shaft.

For controlling the circuits of the organization, there are employed a number of sequence switches which are shown at different points and are designated 100, 200, 300 and 400, respectively. These sequence switches may be of the type disclosed in Patent 1,127,808, issued February 9, 1915, to Reynolds and Baldwin. Each consists of an electromagneticallycontrolled motor or driving mechanism 1 and a number of associated switch cams. The switch cams associated with each of the sequence switches 100 are designated 101 to 103 inclusive; those associated with each of the sequence switches 200 are designated 201 to 224:inclusive,;..those.associated with each of the sequence switches 300 are designated 301 to 304 inclusive; and those associated with each of the sequence switches 400 are designated 401 to 413 inclusive. To each of the contacts associated with the various sequence switch cams are applied certain numerals. These numerals 1n the case of the cams 101, 20-1 301 and 401 indicate the only positions of the associated sequence switch in which these particular contacts are open; the numerals applied to all of the other contacts of eachrsequence switch indicate the only positions of the par.- ticular associated switch in which the associated contacts are closed.

The sequenceswitches 100 merely act as timing switches and have only one resting position. The resting positions of the other sequence switches, and the stages of operation with which these positions are associated, are as follows:

Sequence switch 200.

s wr Sequence switch 300.

1. Awaiting a call. 4. Position vacant. 17. Position busy.

Sequence sioz'tch 400.

1. Normal. 7. Listening in. .15. Listening out.

I The manner in which the system is or.- ganized will appear from the description of its operation which follows. sumed that the subscriber at station A initiates a call. \Vhen the telephone receiver is taken from the switchhook, a circuit is closed that extends by way of both windings of the line relay 12 and both limbs of the telephone line, and is completed in the contacts of the switchhook at the subscribers station. The flow of current in this circuit energizes the line relay 12, which in operating applies at its right -hand armature and contact, a ground to the conductor 18. This causes current to flow from battery through the winding of the relay 19, sequence switch contact 103 (18% to 11;), conductor 18 and ground at the contacts of the operated line relay 12. The relay 19 attracts its armature and closes a circuit that extends from battery through the right-hand winding of the associated relay 24, front contact of relay 19, back contact of relay 22 and lower armature and back contact of relay 23 to ground. Relay 24 operates and closes in its left hand front contact a circuit that extends from battery by way of the winding of the associated group. tri magnet 16' and the left-hand winding 0 the relay 24, in parallel, to the front contact of that relay, and thence'by way of conductor 58, the winding of the relay 22, and the lower armature"and back contactof the relay 23 to ground.

.- -Current flowing in the circuit'traced above operates the trip magnet 16 of the group in which the calling line is located, locks up the relay .24 of the associated group and operates the relay 22 common to all of the groups. The trip magnet 16 rotates its associated trip rod to bring all of the yokes into position to trip the corresponding set of brushes of whichever of the line finder switches is started. The group relay--24 breaks, in its left-hand back contact, the circuit of the conductor 58 to the corresponding relays 24 of the succeeding groups of the series.

The relay 21, in its right-hand front con tact, also completes a circuit that extends from battery through the motor magnet of the sequence switch 100, and contact 102 (18% to 1%) of that switch. In moving out of position 1, sequence switch 100 closes its contact 101 and opens its contact 103 after leaving position 1-1. As contact 101 is closed in all positions excepting position 1 of the It will be asone complete rotation; and as contact 103 sequence switch, the switch is caused to make of the sequence switch is open in all positions exceptingpositions 18% to 11, the 'con- "ductor 18is held openwhile the sequence switch is making its revolution'anduntil it gets backto position 1.- The time required by the sequence switch-to make one complete rotation is so regulated as to be greater than that-occupiedby the line finder switch in finding the terminals of any calling line. The action, therefore, is such as to interrupt the group conductor '18, and hold it open until after the line relay 12 of the calling line has been released as a result of the finding of that line.

- -'and.the tripping of only one set of brushes on a started line finder switch.

The common relay 22, when it operates,

.applies ground to the starting conductor 29 to start a finder switch hunting for the calling line. The startin conductor 29 has branches extending to 1i e sequence switch cams 206 of all of the finder circuits terminating upon the line finders that have access to the .calling line. But, for reasons which will hereinafter be explained, the sequence switch 200 of only one of these finder circuitsis standing in its 2 position. Assuming that this is the sequence switch offinder circuit F, when the relay 22 is actuated by the calling line, as already described, a circuit is completed that extends from battery through the left-hand winding of relay 30, sequence switch contacts 206 (2), conductor 29, front contact and armature of starting relay 22, lower armature and back contact of relay 23 to ground. The right-hand winding of relay 30 is at this time also included 1n parallel with the lefthand windin of the relay inthe energizing circuit, t e parallel branch being from battery through resistance'coil 56, sequence switch contact 217" (2 to 9) right-hand winding of rela 30, sequence SWltChtOl'ltacts'220 (2) an (1 to 13),thereaiter joinin thev conductor that extends from the le t-hand winding of relay 30, and to ground over the circuit already traced. The effect of this is to give the relay 30 the benefit of the energizing action of both windings.

As a result of the closure of the circuit traced above, the relay 30 is energized and closes a circuit that causes the associated sequence switch 200 to move out of position 2. This circuit extends from battery through the motor magnet of the sequence switch 200 sequence switch contact 202 (2), right-hand front contact and armature of relay 30, sequence switch contact 208 (2 to sequence switch contacts 216 (2 to 4) and (2 to 9),front contact and left-hand armature of the relay 30, and armature and back contact of the relay 37 to' ground.

As a result of the closure of its motor magnet circuit in the right-hand front contact of the relay 30, the sequence switch 200 moves out of position 2 and comes to rest in position 3. In position 3 of the switch, a circuit is closed that extends from battery by way of-the up-drive magnet 32 of the corresponding line finder switch LF, conductor 59, sequence switch contact 207 (3 to 4), front contact and right-hand armature of rela 30, sequence switch contact 208 (2 to 7 and to ground by way of conductor 79 and the commutator segment M and associated brush of the corresponding cord finder CS. The energization of the up-drive magnet 32 starts the upward movementof the corresponding elevator rod with its associated sets of brushes. At the outset of the upward movement of the elevator rod, all of the brush trip levers are moved past the corresponding trip yokes. The only trip magnet that is energized in this case is the magnet 16 which corresponds with the group in which the calling line is located; and, consequently, the only trip yoke in position to engage a tri lever on the elevator rod is the one whic controls the brushes 40, 41, 42 and 43 that are adapted to engage the terminals of that particular group of lines. This set of brushes, therefore, is released and made operative and the other sets are held clear of their associated line terminals.

As soon as the set of brushes correspond- 7 sequence switch contact 209 (2% to3), con- '16, the group relay 2% and the common starting relay 22. Relay 23, at its upper front contact, closes a locking circuit for itself and the associated relay 33 that extends by way of conductor 25- and the sequence switch contacts21Q (2% to 1) of all of the finder circuits in series, to ground at a point beyond the last switch-of the series.

As has already been stated, normally there is only one of the finder circuits .with its sequence switch in the receipt of a call. When the call comes in, this sequence switch is immediately moved to position 3, in the manner-described above. Therefore, at this stage of the operation, thesequence switches of allof the finder circuits arev in position to close their contacts 210. The locking circuit for the relays 23 and33 is, therefore, held closed un til another one of the finder circuits has its sequence switch moved into position 2.

This is accomplished by relay 33, which, in

operating, applies a ground to conductor 28 to move the sequence switch of another finder gircuit out of position'l and into position u, and which alsoapplies a ground to the conductor 27 to move' the sequence switch of the appropriated finder circuit out otposition 3.

Assuming that the sequence switch of finder circuit F is in position 1 and that the sequence switch of finder circuit F is in some position between 4 and 17, that findeip' circuit being assumed to be in use, the op eration of the relay 33 completes the 'following circuit: from battery, through the motor magnet and contacts 203(1) of the sequence switch of finder circuit F, contacts 211 (1) of the same sequence switch, contacts 211 (3 to 17) and (4 to 17) of the sequence switch 200 of finder circuit F contacts 211 (3 to 17) and (3 to 3}) of the sequence switch 200 of finder circuit F, conductor 28, lower contact and armature of the relay 33 to ground. This causes the sequence switch of finder cir-' cuit -F to move into position If by any chance the Sequence switch of finder circuit F should fail to be moved into the call-awaiting position 2 when the relay 33 operatesit will be moved into that position when the sequence switch of the appropriated finder circuit F moves into position 5 at a slightly later stage in the operation. The circuit by which this result would, under the circumstances, be accomplished extends from battery through the motor magnet and posit-ion 2 awaiting contact 203 (1) of the sequence switch-of finder circuit F, contacts 211 (1) of that sequence switch, sequence switch contacts 211 (4 to 17) and (3 to 17) of finder circuit F 2 (assumed to be in use), and thence by way of contacts 222 (5 to 1) of all of the finder circuit sequence switches in series to ground. I n other words, at any time that the finder circuit sequence switches are all ,standing in position 1 or in position 5 and beyond, a ground is applied by way of the I 222 cams in series-that moves one of the switches into position 2, and thus places the associated finder circuitin its call-awaiting condition. The sequence switch of finder circuit F is moved out of position 3 by the closure of a circuit that extends from battery through the motor magnet and contacts 203 (-3) of the sequence switch of that circuit, conductor 27 and upper contact and armature of relay 33 to ground, As soon, as the sequence switch of finder circuit F moves into position 2, it opens at its contacts 210 the circuit by way of conductor 25 which has been maintaining relays 23 and 33 energized, and these relays release their armatures. Relay 23, in releasing, reconnects to ground the circuit which'extends in branches 57 and 58 through its Various Sets of group relays, thus again giving the groups access to the starting circuit. l

At this stage of the operation of the systeui, the sequence switch of the appropriated finder circuit F is in position 4, and the elecalling line is located. As the tripped brushes rise. they come into engagement successively with the sets of contacts corresponding with the different lines of the oup. At the inst-ant of engagement of the rush-43 with the terminal 47 of-each line, the test relay 37 of the finder circuit is conmated with local conductor 2530f that line.

This local conductor has two branches, one or the other of whlchis closed depending upon. the condition of the line relay 12. of the associated line. If the line relay inert, as it is when the line is not calling, or when the. line has beenconneotecl with and its cutoff relay operated, the local conductor 253 of the line is connected with'gnound by way of an identifying device 252 and-fa relatively low potential battery. If the li elay 12 is energized, as it is when the linev lling and is not connected with, the local onductor 253 of the line is connected withfground by way of the right-hand back contact and armature of the protective relay 250. common to a group of lines, the energizing winding of this relay, and a relatively high potential battery 251. Therefore, as the elevator rises. and the brush 43 engages the corresponding terminal 47 of each of the lines of the group in which the calling line is located, a circuit is completed as each line terminal is engaged that extends, either by way of the low potential battery, the device 252, and the lefthand back contact and armature of relay 12 to the local conductor 253 of the line; or by way of the high potential battery, the winding of common relay 250, the right-hand armature and back contact of that relay, and the left-hand front contact and armature of relay 12 to the local conductor 253; and thence by way of line terminal 17, brush 43, conductor 51, finder sequence switch contacts 224 (l to 8) and (2+1: to 4), and winding of relay 37 to ground.

The relay 37 is so adjusted that it will respond only to the current flow produced in the circuit of the high potential battery, and not to that produced bythe low potential battery. As the line relay 12 of the calling line is energized, thus connecting the high potential battery to the associated local conductor 253, the test relay 37 responds when the brush 43 engages the terminal 17 of the calling line. The response of the relay 37 causes that relay to interrupt in its back contact the previously traced circuit by way of the left-hand armature and front contact of the relay 30, sequence switch contacts 216, and right-hand winding of relay 30, which circuit had been holding the relay 30 locked up from the moment that the relay was first energized upon the receipt of the call. Relay 30 in releasing its armatures breaks its own locking circuit, and also breaks the previously-traced path, including sequence switch contacts 208, right-hand armature and front contact of the relay 30,-and sequence switch contact 207, over which current has been flowing to energize the up-drive magnet 32 of the line finder. Therefore, the operation of the relay 37 upon the finding of the call-' ing line acts to effect the instant deenergization of the up-drive magnet 32, and thus to stop the brushes upon the terminals of the calling line.

In order that the brushes may always be stopped in registration with the line terminals, the locking circuit of the relay 30 has an alternative path to ground by way of sequence switch contact 215 (2 to 4:), conductor 66, the C segment of the line finder commutator and the corresponding brush to ground. The C segment of the commutator is so formed and related to its brush that the connection between the two is interrupted only when the corresponding line brushes on the elevator rod are in engagement with corresponding sets of line terminals. The unlocking of the relay 30, and the consequent stopping of the upward movement of the elevator rod, can therefore occur only when the line brushes are in proper relation to the terminals of the calling line.

When the relay 30 is denergized, as a result of finding the calling line, it also completes a circuit that extends from battery through the motor magnet and contact 202 (3 to 1) of the finder sequence switch, righthand back contact and armature of the relay 30, sequence switch contact 208 (2 to 7), conductor 79, and M segment and corresponding'brush of the cord selector OS to ground. The closure of this circuit moves the sequence switch out of position 4.

When the finder sequence switch reaches position 4%, it closes a path for the flow of current through the cut-ofi relay 11 of the calling line by way of resistance coil 61, sequence switch contact 212 (4% to 12%), con ductor 50, crush 42, line terminal 46 and conductor 53." The flow of current in this circuit operates the cut-off relay 11 to disconnect the relay 12 from the circuit, and that relay in releasing its armatures disconnects the high potential test battery from the local conductor 253 and disconnects ground from the common conductor 18.

The disconnection of ground from conductor 18 occurs before the timing sequence switch 100 has completed its cycle of rotation and reconnected conductor 18 with relay 19. T I

The brushes of the line finder switch are now at rest in engagement with the terminals of the calling line, the sequence switch 200 of finder circuit F is at position 6, the group starting circuit represented by the conductors 57 and 58 and the associated. relays 22, 23 and 33 has been released and is in readiness to respond to another calling line, and the sequence switch of another finder circuit has been moved into position 2, and thus brought into operative relation with the starting conductor 29.

When the sequence switch of the finder circuit over which the call is being extended has reached position 6, the finder circuit is brought into operative relation with the operators selecting circuit. When the finder sequence switch reaches position 6, it awaitsthe closing of a circuit, the completion of which is dependent upon the condition of the other finder circuits of the associated group. This circuit extends from battery through the left-hand winding of the relay 30, contact 219 (6) of the appropriated circuit sequence switch. contacts 219 (9 to 4) f the sequence swit hes of the associated nder circuits preceding it in the series, conductor 76, outer armature and back contact of relay 54, and right-hand back contact and armature of relay 61 to ground. A branch path for the energization of relay 30 also exists at this time, this branch path extending t'ronibattcry through resistance 56. sequence switch (Olll'tl'iS 217- (9 to 9), right-hand winding of rclav. 30.

ated finder circuit sequence switch, from which point it extends to ground at the right-hand 'back contact and armature of the relay 61 overthe path'already traced. This circuit for the energization of relay 30 is open either in the cam 219 of a preceding finder sequence switch in the series, or in contacts of the relay 54 or 61 as long 'as any sequence switch'of the series tions 4 to 9. That is, it is open time the line finder switch of is in po'sifrom the any assoc1- ated finder circuit finds a calling line until the cord finder switch of that circuit has moved far enough to trip the brushes corresponding with the selected operators position, as will be described. Not until this has occurred will the above traced circuit of the awaiting finder circuit be closed. When the circuit is closed, the relay 30 attracts its armatures and completes a circuit that extends from battery through the motor magnet and sequence switch contact'202 (6 to 7) .of the sequence switch 200, righthand front contact and armature of relay 30, sequence switch contact 208 (2 to 7), conductor 79, and segment M and corresponding brush of the cord selector commutator to ground. The completion of this circuit moves finder sequence switch out of position 6.

When the sequence switch 200 reaches position 6?; it closes a circuit that extends from battery y way of the winding of relay 55 (Fig. 3), conductor 71, sequence switch contact 218 (6% to 8), conductor 67, and segment M and corresponding brush of the line finder commutator to ound. The operation of the relay 55 applies ground to the conductors 81 extending to all of the operators positions. At each" of the positions where the operator is at her station and is in readiness to receive a call, the associated relay 91' (Fig. 4) is inert, and the operatorstelephone sequence switch 300 is in its 1 position. Consequently at each of such positions, a circuit is closed that extends from battery, through the winding of the associated relay 92, lefthand armature and back contact of relay 91, sequence switch contact 304 (1), conductor 81, armature and front contact of relay 55 to ground. The relay 920i each awaiting position therefore attracts its armatures and closes a circuit that extends from battery, through the front contact and armature of the relay 92 to the conductor 82, and thence to ground byway of the windings of the relays 77 corresponding to that operators position at the various cord selector frames.

When the finder sequence switch 200 1 reaches position 7, in which position it comes to rest, it closes a circuit that extends from batterytbrough the winding of relay 54, lefthand back contact and armature of relay 61, conductor 73, finder sequence switch contact and 94 are energized 218 (7 to 8), conductor 67, and segment M and corresponding brush of the line finder commutator to ground. Relay =54 attracts its armatures and completes a branch of the circuit traced above, which branch extends from conductor 73 by way of the armature and back contact of the relay 63, front contact and inner armature of relay 54, righthand armature and back contact ofrelay 52, armature and front contact of relay 77 (which relay is energized, as previously described, as a result of the corresponding operators position being in readiness to receive a call), right-hand backcontact and switch spring of relay 93 of the corresponding group, winding of associated relay 94, winding of relay 93, left-hand switch spring and resting contact of relay 93, conductor 83, left-hand back contact and armature of relay 95 at the O operators position to battery. Upon the closure of the above-. traced branch circuit, group relays 93 in parallel with the relay 54. Relay 93 in operating disconnects its own energizing winding and that of relay 94 from the previously traced path to battery by way of the left-hand back contact and armature of relay 95,- and connects them in a path which extends to battery by way of conductor 84 and the winding of the relay 95. This causes the relay 95 also to be energized and to interrupt in its left-hand armature and back contact the path by way of conductor 83 over which the relays 93 and 94 were initially energized.

Relay 94 in operating closes a circuit from battery through the winding of the trip magnet 20 corresponding to the selected operators position, and to ground by way of the right-hand armature and front contact of the relay 94. This relay also closes a circuit that extends from battery through the winding of the relay 63 and the left-hand ar-' mature and front contact of the relay 94 to ground. The relay 63 in operating closes a branch that extends from the conductor 73 (grounded by way of contact 218 (7 to 8) of the line finder sequence switch) through the'armature and front contact of relay 63, back contact and armature of relay 254, conductor 72, sequence switch contacts 220 (7) and (1 to 13), and left-hand winding of relay 30 to batter A branch energizing path for relay 30 also extends from conductor 72 by way of sequence switch contacts 220 (7 right-hand winding of relay 30, sequence switch contacts 217 (2 to 9), and resistance 56 to battery. Relay 30 attracts its armatures and closes a circuit that extends from battery through the motor magnet and sequence switch contact 202 (6 to 7), front contact and right-hand armature of relay sequence switch contact 208 (2 to 7), conductor 7 9, and segment M and corresponding brush of the cord selector commutator to ground. .The closure of this circuit moves sequence .switch 200 out of position 7. Furthermore, relay 30 in operating is locked up over a circuit that extends from battery through resistance 56, sequence switch con tacts 217 (2 to 9) right-hand winding of relay 30, sequence switch contacts 216 (7 to 9) and (2 to 9), front contact and left-hand armature of relay 30 and armature and back contact of relay 37 to ground.

When the sequence switch reaches position 8 it closes a circuit that starts the upward movement of the brush-carrying rod of the cordselector switch, this circuit extending from 'battery through the up-drive magnet 34 of the cord finder, conductor 89, sequence switch contact 207 (8 to 9), right- 'hand front contact and armature of relay 30, sequence switch contact 218 (8 to 9), conductor 67, commutatorsegment M of the line trol of a s 0w releasing relay 254. The energizing winding of the slow releasing relay 254 is in parallel with the energizing winding of the relay 54, and the relay 254: is consequently energized by way of conductor 73 and cam 218 of the finder sequence switch when the sequence switch reaches position 7. The energizing path of the relay 254' is by way of the back contact and armature of relay 63, and the armature andback contact of relay 254: controls the path to relay 30 by way of the conductor 72, holding this path open as long as the relay 254 is energized. \Vhen therefore the actuation of one of the relays 94c operates the relay 63, the operation of the relay 63 does not instantly close conductor 72 to energize relay 30 and move the finder sequence switch to position 8 where the upward movement of the cord selector brushes is started. Instead, the closure ofthis energizing path for relay 30 is delayed until the relay 254: has had time to denergize, after the interruption of its circuit at the back contact of relay 63, and release its armature to close the path of conductor 72. Under certain special circumstances in the operation of the operators sele"ting apparatus it is possible for the trip n'agnets associated with two operators positions on the same cord selector frame, or for two trip magnets associated with same operators position upon two different frames, to be momentarily operated. By providing the slowacting relay 254 for delaying the advance of the finder sequence switch to its next stage,

the possibilitv of one finder circuit selecting two operators positions, or of two finder circuits on different frames selecting the same operators position, is prevented.

At the outset of the upward movement of the cord finder brush rod, the tripping levers of the various sets of brushes are brought simultaneously into operative position with respect to the corresponding trippingyokes, and that set of brushes is tripped and made operative whose trip magnet is at the time energized. In the present instance, it is assumed that this is the trip magnet 20 associated with the terminals of the group of connecting cord circuits extending to the O operator position.

Immediately after the set of brushes is tripped, the common operators selecting circuit is restored so as to be available for the use of other cord finder switches. This is effected through the medium of a circuit that is completed by the grounding of the K segment of the cord finder commutator, this segment being so located as to be engaged by its brush immediately after the tripping levers of thesets of brushes pass the associated tripping yokes. The circuit referred to extends from battery through the winding of relay 6'1, conductor 7 41, sequence switch contact 221 (75} to 8), conductor 80, cord finder commutator segment K and its corresponding brush to ground. Belay 61 in operating '0 ens, at its left-hand back contact, the prevlously-traced circuit by way of conductor 73 which, up to this time, has been holding energized the relay 95 atthe O operators position and the relays 93 and 9% corresponding to this position on the cord finder frame. The release of the relay 91 del'nergizes the 7 corresponding trip magnet 22 and the common relay 63. The deenergization of the relay 93 restablishes, subject to the release of relay 61, the control of other finder circuits over the brush tripping mechanism of the associated cord finder frame.

Relay 61, in operating, closes a locking circuit for itself by way of conductor 73, sequence switch contact,218 (7 to 8), conductor 67, commutator segment M of the line finder and corresponding brush to round. It also completes a circuitthat extends from battery through the motor magnet and contact 20l (8) of the sequence switch 200, conductor 75, right-hand front contact and armature of relay 61 to ground. The closure of this circuit moves sequence switch 200 cut of position 8. In moving out of position 8, the sequence switch opens its contacts 218 (7 to 8), thus dei nergizing relay 61 and again extending cond'uctor73 to the relay 54 and the conductors over which the oper: ators selection-is effected. In closing its right-hand 'back' contact upon release, relay 61 also restores the continuity of conductor 76 and makes it available for moving out of position 6-the sequence switch of some other through the motor magnet and cam 403 (1) finder circuit which may be waiting'for acof the listening key sequence swltch and cess to the operators selecting circuit.

After the cord selector switch CS passes the brush-tripping position, it continues its upward movement until the brushes are stopped by engaging the terminals of one of the connecting circuits that is not in use. The idle or busy'condition of the connecting circuit is indicated by the presence or absence of high-potential batteryon the test terminal 118 of each connecting circuit.

When the brushes engage the terminals of an idle connecting circuit, -,-apath for the flow of current is completed from high-potential battery 251 (see Fig. 4), through the winding of common protective relay 258, armature and back contact of that relay, lower back contact and armature of relay 259, conductor 128, armature and back contact of relay 420, contact 406 (1) of the listening key sequence switch, conductor 88, test terminal 118 and brush 114 of the cord selector, conductor 99, finder sequence switch contacts 206 (8 to 9) and the Winding of relay 37 to ground. .Relay 37 thereupon attracts its armature and opens the previously traced locking circuit that has been holding relay 30 energized. Relay 30, in releasing its armatures, opens at its right-hand front contact and armature the'energizing circuit for the up-drive magnet 34, thus stopping the brushes of the cord selector switch in engagement with the terminals of the selected connecting circuit. In engaging .its back contact, the right-hand armature of relay 30 closes an energizing circuit for the motor magnet of the finder sequence switch which extends by way of cam 202 (8 to 9), back contact and right-hand armature of relay 30, cam 218 (8 to 9), conductor 67, and the M segment and corresponding brush of the line-finder commutator to ground; The closure of this circuit moves sequence switch 200 out of position 9, whereupon the switch continues to move until'it reaches position 14, where the talking circuit is completed at cams 213 and 214. l v An instant after the finder sequence switch leaves position 9, it closes a circuit that ex tends from battery through the windings of relays 421 and 423 (see Fig. 4) in parallel,

listening key'sequence switch contacts 407 (1), left-hand back contact and; armature of relay 422, conductor 87, cord selector switch terminal 117 and corresponding brush 113, conductor 98, and finder sequence switch contacts 217 (9} to 14) and (9?;- to 11) to ground. Relay 421 in operating closes a locking circuit for itself and relay 423 that extends by way of its upper front contact and armature, and sequence switch contact 405 (1 to 6) to ground. Relay 421 also closes a circuit that extends from battery open the test conductor 88 at sequence switch.

Contact 406 (l) and also to open at sequence switch contact 407 (1) the path over which the" relays 421 and 423 were first energized. Relay 423, associated withrelay 421, in operating closes a circuit that extends from battery through the .winding of relay 422 and upper front contact and armature of relay 423 to ground. As a result relay 422, prior to the moving of the listening key sequence switch out of position 1, has disconnected conductor 87 from connection with batter by way of sequence switch contact 407 (1' and the windings of relays 421 and 423, and has connected it with an alternative'path to battery'by way of the left-hand front conrelay 259, conductor 129, and lower front contact and armature of relay 423 to ground. Relay 259 in operating opens at its lower armature and back contact the circuit over which the potential of the high voltage test battery 251 is supplied to the test conductors 128 of all of the connecting cords of the position. Thus the electrical condition which permits a connecting cord to be seized by a cord select-or is withdrawn from the selected cord and also from its associated cords at the instant of seizure, and is not reapplied to such of the cords as may be in COIldltlOIL to be selected untiluthe common relay 259 is deenergized. The deenergization of relay 259 occurs when the relays 421 and 423 are released by the opening of their locking circuit at cam 405 when the listening key sequence switch moves beyond position 6. 7

When the listening key sequence switch 400 is moved out of position 1, in the manner described above, it continues its movements until it reaches position 7. In position 7 the cams 408, 409, 410 and 411 of the listening key sequence switch interrupt the talking strands of the connecting circuit and include between their severed ends a loop that has switch contact 113 (7), and interrupter 162 to ground.

At this particular time the operators sequence switch 300 is in position 17 or moving to that position. When the position was selected the operators sequence switch was standing in position 1 and the relay 91 was inert, thus providing a path for the energizatlon of the relay 92, the operation of which relay when an operators posltlon is to be selected serving to mark that particular position as being unengaged or selectable. Then the position is selected, the relay 95 is operated in the manner previously described. In operating, the relay 95 closes a circuit that extends from battery through the motor magnet and cam 302 (1) of the operators sequence switch, right-hand front contact and armature of relay 95, and right hand front contact, and armature of relay 125 to ground. The relay 125 at this time is operated, as its energizing path is completed by way of local contacts 127 of the operators telephone jack 126-, which contacts are closed when the operator is at her position and has her telephone plug inserted in the telephone jack. As a result of the closure of the circuit traced above, the operators sequence switch 300 is moved out of position 1, thus of relay 92 in sequence switch contact 303 (1) and making the position unselectable. The next resting position of the, operators telephone sequence switch 300 is position 4:; but as relay 125 is' energized, the motor magnet has an energizing circuit in this position by way of sequence switch contact 302 (1) and the left-hand front contact and armature of relay 125 to ground, and consequently the sequence switch moves on to its next resting position 17. The sequence switch remains in position 17, keeping the operator position unselectable, until at a later stage in the operation the switch 192 is operated in any suitable manner to close its contacts. At this time a circuit is closed that extends from battery through the motor magnet and cam 302 (17) of the operatorfs telephone sequence switch and closed contacts of switch 192 to ground. The closure of this circuit permits the sequence switch to move from position 17 to position 1, thus rendering the operators position again available for receiving calls.

The opcrators posltion is also rendered unsclectable when the operators telephone set is connected with one of the connecting circuits. This is effected through the meopening the energizing path...

dium of the relay .91. WVhen the listening key sequence switch 400 of any of the connecting circuits of the operators position is moved to position 7 to bring the operators telephone set into connection with the corresponding circuit, an energizing path is completed that extends from battery through the winding of relay 91, conductor 137, and listening key switch contact 404C (2 to 9) to ground. The completion of this circuit causes the relay 91 to attract its armature and interrupt the path over which the relay 92 is adapted to be energized, thus preventing the operation of the associated selection controlling relays 7 7.

The removal of the telephone plug from the operators telephone jack 126 when the operator leaves her position, also renders the position unselecta-ble. When the plug is removed, the breaking of the circuit at the local contact 127 causes relay 125 to become inertand release its armatures. This closes a circuit that extends from battery through the motor magnet and cam 302 (1) cf the operators telephone sequence switch, and to groimd by way of the left-hand back contact and armature of relay 125. In moving out of position 1 as the result of the closure of this circuit, the sequence switch interrupts the energizing path for the relay 92 in sequence switch contact 303 (1), thus preventing the operation of the corresponding selection controlling relays 7 7 when a connection is to be extended.

Reference has heretofore been made to the operation of the common relay 259 which is energized to remove the test condition from the selected connecting cord and all of its associated connecting cords at the instant the cord is seized. This relay when it operates, also acts to complete a circuit that extends from battery through the winding of relay 91 and the-winding of relay 193 in parallel, and thence to ground by way of the upper front cont-act and armature of relay 259. Relay 193 in operating, closes a circuit, from battery through the motor magnet and contact 304 (1) of the operators telephone sequence switch, and frontcontact and armature of relay 193 .to ground. The closure of this clrci'ut safeguards the operators telephone sequence switch from standing or stopping in position 1 from the instant the cord circuit is seized. Relay 91 in operating insures the inaccessibility of the operators position at this time by opening the path over whch relay 92 must be energized.

When the operator has been put into communication with the calling subscriber by the movement of listening key sequence switch 400 to position 7, as already described. and when the operator has learned the number of the line that is wanted, the connection may be completed by inserting calling plug 425, in which, in the present instance, the connecting circuit is represented as terminating. into the spring jack 14 of the called subscribers line. Instead of a plug and spring jack, any other of the well-known switching devices or mechanisms .for establishing connection between a connecting clrcult and a telephone 11118 may and may operate in the usual way, a description of them and of the exact manner in which the cord circuit is organized is thought to be unnecessary.

When the calling plug 425 is inserted in the called line spring jack, an energizing circuit is completed that includes serially the windings of the connecting cord relays 420 and 431 and the cut-off relay 11 of the called line. The cut-ofi' relay 11 may have its usual function of disconnecting the line relay 12 thus depriving the line of control over the calling apparatus. The relay 420 in operating interrupts at another point the path of the test conductor 88, thus keeping the cord circuit nnselectable while the plug 425 is in the spring jack of the called line.

The relay 431 at its left-hand back contact breaks the connection of the tip of the plug with the conductor 133, which may extend to the test winding of the operators telephone set. and atits left-hand frontcontact closes the tip strand of the connecting cord to complete the talking circuit. The relay 43] in operating also closes a circuit that extends from battery through the winding of the relay 500 and the right-hand front contact and armature of relay 431 to ground. The relay 500 at its outer armature and back contact interrupts the circuit of the flashing call lamp 161; and extinguishes the lamp. At its inner armature and front contact, the relay 500 closes a locking circuit for the holding relay that extends by way of the right-harid front contact and armature of that relay. The relay 500 also closes a circuit that extends from battery through the motor magnet and contact 402 (7) of the listening key sequence switch, outer lefthand front contact and armature of relay 500, and right-hand back contact and armature of relay 421 to ground, the relays 421 and 4.23 having been released by the opening of their locking circuit at cam 405 when the listening key sequence switch moved'bcyond position 0. The listening key sequence switch moves out of listening-in position 7 as a result of the closure of this last mentheir armatures.

tioned circuit, and comes to rest in posi tion 15.

The termination of the conversation between the subscribers is indicated in the usual way by signals displayed when the supervisory relays 427 and 428 become inert, and disconnection is effected by withdrawing the calling plug 425 from the spring jack 14 The withdrawal of the calling plug 425 interrupts the energizing circuit of the relays 431 and 420, and these relays release The relay 431 in releasing breaks the energizing circuit of the relay 500, and that relay in releasing closes a circuit that extends from battery through the motor magnet and cam (15) of the listening key sequence switch outer left-hand in releasing, breaks the connection of con-- ductor 87 with battery by way of the device 424. Q When current ceases to flow through conductor 87, the relay 30 of the finder circuit, which has been included in the path of current flow by way of conductors 8T, 98, 50 and 53, and the finder sequence switch cams 217 and 212, releases its armatures. This closes the circuit from battery through motor magnet and cam 202 (14) of the finder sequence switch, left-hand back contact and armature of relay 30, and armature and back contact of relay 37 to ground. This moves the finder sequence switch out of the talking position 14.

When the finder sequence switch reaches position 15 a circuit is closed for the energization of the relay 30 that includes in parallel branches both windings of that relay. One branch of this circuit extends from battery through resistance 56, sequence switch contacts 217 (15 to 16) and (12 to 16) righthand winding of relay 30, sequence switch contacts 220 (15) and (11. to 16) to conductor 67; theother branch extends from battery, through the left-hand winding of relay 30. and sequence switch contacts 220 (15) and (11 to 10) to conductor 67 thence both branches extend by way of conductor 67 and M segment and corresponding brush of the line-finder commutator to ground. Relay '30 in operating closes a branch path to ground for n'iaintaining its energization, this path extending from the right-hand Winding of relay 30, by way of sequence switch tator to ground.

Y contact of relay and contact 202 (15) of the finder sequence switch, right-hand front contact and armature of relay 30, sequence switch contact 218 (15), conductor 67 and M segment and corresponding brush of the line-finder commu- The completion of this circuit energizes the finder sequence switch 200 and causes it to move its cams to position 16.

' In moving out of position 15 the sequence switch opens at its 220 cam, the branch ofthe energizing path that includes the lefthand winding of relay 30, and also opens the path to ground by way of.conductor 67 and the M segment of the line-finder commutator; the energization of the relay being maintained in position 16 of the sequence switch by way of the branch that includes its right-hand winding, cam 216, left-hand contacts of relay 30, and resting contacts of relay 37. This circuit is held closed and relay 30 is kept energized until the cord circuit through which the call was extended has returned to its normal condition. When this occurs a clrcuit is closed that extends x (9 to 17) and (16), and winding of relay 37 to ground. The closure of this circuit energizes relay 37, which attracts its armature and opens the previously-traced holding circuit of the relay 30. 'Relay 30in releasing its armatures closes a circuit that extends from battery through the windin of downdrive magnet 62 of the line-finder switch, conductor 60, sequence switch contacts 223 (16 to 7) and (16 to 16%), left-hand back contact and armature of relay 30, and armature and back contact of relay 37 to ground (the energizing circuit of relay 37 having been interrupted at the right-hand front contact and armature of relay 30 when that relay released). :As a result of the closure of this circuit, the brushes of the line-finder switch are returned to normal.

-It will be noted that the circuit-for energizing the down-drive magnet 62 of the line nder is not closed until relay 30 has been released as a result of the energization of relay 37, and that relay 37 is not released until the circuit by way of conductor 88 of the connecting co r d circuit is closed by the complete return of the connecting cord circuit to its normal condition. As a result of this arrangement it is possible, by holding the connecting cord circuit and preventing the closure of listening key sequence switch contact 406 (1), to hold the brushes of the line-finder switch in engagement with the terminals of the calling line, even after the act of disestablishing the connection has been initiated by the release of the holding relay 30 andthe movement of the finder sequence switch out of the talking position 14. This feature is desirable where, for instance, the relay30 of the finder circuit is accident ally released immediately after the finder circuit is extended to a connecting circuit, and before connection with the called line is completed. In this case, when the operator answers in response to the flashing of the lamp 161, she finds that the calling subscriber is not conne ted with the circuit, the finder sequence switch havin moved out of the talking position 14 and fiaving come to rest in position 16. As the energizing circuit of the down-drive magnet 62 of the line finder cannot be closed in position 16 until conductor 88 is closed at sequence switch contact 406' (1) by the return of the listening key sequence switch to normal, the operator is able, by holding the listening key sequence switch in position 7, to prevent the return of the line finder until the switchboard attendant has been notified and hasv identified the finder circuit that has failed to operate properly. When this'has been done, the connection may be released and the line finder switch permitted to return to normal by causing the listening key sequence switch to move to position 1 and close, at contact 406 (1), the circuit of conductor 88. The operator may accomplish thisby press ing'the listening-out key 432,- which closes a circuit for moving the listening key sequence switch out of position 7. The switch moves through position 15 on account of the energizing pathfor its motor magnet completed by way of sequenceswitch contact .402 (15), outer left-hand back contact and armature of relay 500, and lower back contact and armature of relay 421, and comes to rest in position 1.

As the line-finder brushes reach normal, a circuit is closed that extends from battery through the motor magnet and contact 204 i (16) of the finder sequence switch, conductor 69, and Y segment and corresponding brush of the line-finder commutator to ground. When-the finder sequence switch moves to position 17, as a result of the closure of the above traced circuit, a circuit is completed that extends from battery through the winding of the down-drive magnet 35 of the cord selector, conductor 90, finder sequence switch contact 218 (17 conductor 67, and M segment and corresponding brush of the line finder commutator to ground. The closure of this circuit returns the cord selector switch to normal; and as the brushes reach'normal a circuit is closed that extends from battery through the wind- I process of establishing or disestablishing a 52 opens the path over which" and 94 corresponding with the connection is as has been described in the foregoing. It may, however, occasionally happen in the operation of'the system that for some reason, line relay 12 or the failure of the cut-ofl relay 11 to operate, that the high potential test battery which identifies the calling line is not removed from the finder. switch test terminals of that line when.the line is con" nected with. The manner iii which the system is organized to care for this particular condition when it arises will now be described.

It will be remembered that when the finder switch makes connection with the calling line the sequence switch 200 is moved out of position 4, and that when the sequence switch reaches position 4;}, a circuit is closed by way of cam 212 and conductors 50 and 53 for energizing the cut-off relay 11 of calling line and bringing about the release of the associated line relay 12. If for any reason the line relay fails to release its armatures, the high potential identifying battery 251 remains in connection with the test conductor'253 of the associated line. Consequently when the finder-sequence switch moves out of position 6 upon the finder circuit gaining access to the operators selecting circuit, a circuit is closed that extends from the high potential test battery 251, the winding of the common protective relay 250, the armature and back contact of that relay left-hand front contact and armature of line relay 12, test conductor 253, test terminal 47 and corresponding test brush 43 of the line-finder, conductor 51, contacts 224 (1 to 8) and (6 to 8) of the finder sequence switch, conductor 260, and right-hand winding of relay 52 of the circuit to ground. Therefore the presence of the test potential at atime when in the normal operation it should be. absent, causes the energization of the delay 52. Relay 52, in operating, closes a locking circuit for itself that extends from battery through the left-hand winding of relay 52, left-hand frontcontact and armature of that relay, conductor 71, finder sequence switch contact 218 (6g to 8), conductor 67, and the M segment and corresponding brush of the linefinder commutator to ground. At its righthand. armature and .back contactfthe relay the impulse of relays 93 available operators'po'sition. Thus, when, an instant must fiow that operates the set such as the sticking of the operators selecting later, the finder sequence switch reaches position 7, the ground that is applied to conductor 73 by the closure of finder sequence switch contacts 218 (7 to 8) does not pass to one or another of the sets of relays 93 and winding of relay 30, contacts 220 (l to 13) and (7) of the finder sequence switch to the same conductor 72. Thence the circuit continues by way of the right-hand front contact and armature of relay 52, inner arma- 2 ture and front contact of the relay 54, back contact and armature of relay 63, back contact and armature of relay 61, conductor 73, finder sequence switch contact 218 (7), conductor 67, and segment M and corresponding brush of the-line-finder commutator to ground. Relay 30 attracts its armatures and closes a circuit that extends from battery through the motor magnet and cam 202 (6 to 7) of the finder sequence switch, righthand front contact and armature of relay 30, contact 208 (2 to 7) of the finder sequence switch, conductor 79, and segment M and corresponding brush of the cord selector commutator to ground. The closure of this circuit moves the finder sequence switch to position 8. Relay 30 in operating also closes a locking circuit for itself that includes its right-hand winding and extends to ground by way of contact 216 (7 to 9) and (2 to 9) of the finder sequence switch, left-hand front .contact and armature of relay 30, and armature and back contact of the relay 37.

The movement of the" sequence finder switch to position 8 and the operation of the relay 30, closes the circuit of the cord selector updrive magnet 34 in a manner that has already been described, and the brushes of the'cord selector switch start to move up. .But as'the energization of the relay 52 has prevented the operation of any of the sets of relays 93 and 94 of the operators selecting apparatus, none of the trip magnets 21, 22 is actuated, and consequently the sets of brushes are moved past the tripping position without any of the sets being tripped. As the tripping position is passed, the grounding of the K segment of the cord selector commutator completes the circuit for energizing'the relay 61 of the operators selecting aliparatus, and that relay closes the circuit y way of contacts 204 (8) of the finder sequence switch that causes the sequence switch to move out of position 8 The circuit just and into position 9, as already described. In position 9 of the finder sequence swltch the upward movement of the cord selector brushes continues. But as none of the sets of brushes has been tripped to make it operative, the brush carrying rod or elevator goes to the limit of its upward movement, and there grounds the X segment of the cord selector commutator. This closes a circuit that extends from battery through the motor magnet and contacts 205 (7 to 14:) and (1 to 16) of the finder sequence switch (the switch being in position 9 at the time), conductor 70, and X segment and corresponding brush of the cord selector commutator to ground. As a result of the closure of this circuit the finder sequence switch is moved through its positions up to and including position 14, coming to rest in position 15.

In position 15 of the finder sequence switch an energizing circuit is closed for both windings of the relay 30, one branch of this ener-. gizing circuit extending from battery through resistance 56, finder sequence switch contacts 217 (15 to 16) and (12 to 16), righthand winding of relay 30, and contacts 220 (15) and (11 to 16) of.the finder sequence .switch to conductor 67, and the other branch extending from battery through the lefthand winding of relay 30, finder sequence switch contacts 220 (15) and (11 to 16) to the same conductor 67. Thence the path is to ground by way of the M segment and corresponding brush of the line-finder commutator. Relay 30, in operating, closes a circuit for itself that includes its right-hand winding and extends through finder sequence switch contacts 216 (15 to 16), left-hand front contact and armature of relay 30, and armature and back contact of relay 37 to ground. Relay 30 in operating also closes at its right-hand front contact and armature a circuit for moving the finder sequence switch out of position 15, as previously described.

In both positions 15 and 16 of the finder.

sequence switch a circuit is completed that extends from battery through the Windingof relay 255, finder sequence switch contacts 205 (15 to 16) and (1 to 16), conductor 70 and X segment and corresponding brush of the cord selector to ground. Relay 255 in operating closes at its upper armature and front contact an energizing circuit for the lamp 257, and the illumination of the lamp indicates to the switchboard attendant that a cord selector switch is at tell-tale; that is, that its brushes have passed beyond the selectable contacts and are at the limit of their upward movement. The attendant thereupon may inspect the cord selectors of the associated frame, note the selector switch that is at tell-tale, ascertain the number of the line upon which the brushes of the correary 31, 1916;

tery through the winding of the down-drive magnet 62 of the associated line finder, conductor 60, finder sequence swltch contacts 223 (16 to 6%), right front contact and armature of relay 255, and the closed contacts of switch 256 to ground. The closure of this circuit restores the line-finder to its normal position. The grounding of the Y segment of the line-finder commutator when the brushes are returned moves the line-finder sequence switch out of position 16 and into position 17, the movement of the finder SQ- "quence switch into position 17 closes the energizing circuitof the down-drive magnet 35 of the cord selector, and the return of the cord selector brushes to their normal position grounds the Y segment of the cord selector commutator and moves the finder sequence switch to its normal or 1 position, all as has heretofore been described in connection with a normal operation of the organization.

From the foregoing it may be seen that the organization is such that when, through any improper operation of the apparatus, the test potential is not removed from the calling line when that line is connected with, the finder circuit is immediately deprived of any control over the operators selecting circuit and the corresponding cord selector switch is moved to tell-tale and a signal 'ven the switchboard attendant, the cord selector being held at tell-tale and the associated line-finder being held on the terminals of the calling line ifthe switch 256 is open, and thefinder circuit and switches being automatically returned to normal if the switch 256 is closed. The failure of the line relay to release is thus prevented from extending the line that is in trouble to an operators position.

In order that the features to which this invention is directed may be fully and clearly disclosed, it has been necessary to describe them in connection with other features that are the subject of copending applications assigned to same assignee, such applications including the applications of S. B. Williams, Jr., Serial No. 75,328, filed January 31, 1916; Serial No. 75,329, filed Janu- Serial No. 107,090, filed July 1, 1916, and the application of F. A. Steal-n. Serial No. 107,540, filed July 5, 1916. Such other features are the subject of claims in the applications mentioned above, and are not claimed in the present application.

calling line in establishing connection there with, operator selecting apparatus associated with said finder circuit a test magnet responsive to the altered'electrical conditionof a connected telephone line, and means controlled in the response of said test magnet for rendering said operator selecting apparatus inoperative.

. 2. The combination with a plurality of telephone lines, of a source of test current, means associated with each line for connecting said source with said line in calling, a finder circuit responsive to said test current for making connection with the calling line,

means for disconnecting said source from said calling line in establlshing connectlon therewith, selecting apparatus controlling a further extension of said finder circuit, a

test magnet associated therewith responsive to a continuance of said current on the calling line after the finder circuit has estab-' lished connection therewith, and means controlled in the response of said test magnet for rendering said selecting apparatus inoperative.

3. The combination with a plurality of finder circuits, of a plurality of operators positions common selecting apparatus. controlling the extension of said finder circuits to said operators positions, a test magnet associated with said common selecting apparatus for rendering the same temporarily.

inoperative, a source of current for operating said test magnet, and means for bringing. said source into connection with said test magnet by way of any of said finder circuits when such circuit is in abnormal con.-

dition, whereby an abnormal condition of a finder circuit prevents the same from selecting an operator. 7 a

4. The combination with a plurality of telephone lines, of a plurality of operators V positions, a plurality of finder circuits for establishing connection between any line and any operators position, common selecting apparatus controlling the extension of a finder circuit to an operators position, a test magnet for rendering said common selecting apparatus temporarily inoperative, a source of current for operating said test magnet, and means rendered operative by an abnormal condition of any connected line for applying said source .to said test magnet.

5. The combination with a plurality of operators positions, of a plurality of circuits adapted to be extended thereto, selecting apparatus common to said circuits and said positions, said selectingapparatus actmg to control the extension of any of sald clrcults to any operators positlon, a source of current, means operating under abnormal conditions for applying said source of current to any of said circuits, and means responsive to the application of said source of current to any said circuits for rendering said common selecting apparatus temporaany connected line for operating the aforesaid preventing means.

7. The combination with a plurality of telephone lines, of a finder'circuit for making connection therewith, a plurality of connecting circuits, a switch for extendingthe connection of said finder circuit to an idle one of said connecting circuits, means for preventing said switch from extending the connection of said finder circuit, and means for actuating said preventing means made operative by an abnormal condition of any line connected with said finder circuit.

8. The combination with a plurality of telephone lines and a plurality of connecting circuits, of a finder circuit provided with a finder switch for making connection with any of said telephone lines and a. se lector switch for making connection with any of said connecting circuits, a source of test current, means for applying the same to any of said lines in calling, means actuated in establishing connection with a calling line for withdrawing said source of test current, and means responsive to thereontinuance of said test current on a calling line afterconnection is made therewith for preventing said selector'switch from establishing connection with any of said connecting circuits.

9. The combination with a telephone line, of a source of test current, means for connecting said source with said line'in calling, a finder circuit providedwith a finderjswitch responsive to said source of test current to establish connection with a calling line, means operated in establishing connection for disconnecting said source of test fcurrent, means for further extending said finder circuit, and means operated by the continued connection of said source with said line after the finder switch has connected therewith for preventing'the operation of said circuit extending means.

10. The -combination with a telephone line, of means for altering the electrical condition of the same in calling, a finder circuit responsive to the altered "condition of said calling line for making connection therewith, means operated in .establishing ing circuit, means for extending said finder.

circuit to said' connecting circuit, and means responsive to the continuation of the altered electrical condition of said line after connection is made therewith for preventing the operation of said extending means.

11. The combination with a telephone line, of means for altering the electrical condition of the same in calling, a finder circuit responsive to the altered condition of said calling line for making connection therewith, means operated in establishing said connection for restoring the, normal electrical condition of said line, a connecting circuit, a switch for connecting said finder circuit with said connecting circuit, an emergency device, and means responsive to the continuation of the altered electrical condition of said line after connection is made therewith for preventing said switch from extending said finder circuit to said connecting circuit and causing it to operate said emergency device.

12. The combination with a telephone line and a cord circuit, of a finder circuit, a switch for connecting said finder circuit with said telephone line, means for connecting said finder circuit with said cord circuit, a sequence switch associated with and controlling said cord circuit, means actuated in connecting said finder circuit with said cord circuit for moving said sequence switch out of its normal position, and means made operative by the return of said sequence switch for moving said finder switch to disconnect said finder circuit from said telephone line.

1%. The combination with a telephone line and a cord circuit, of a finder circuit,

means for connecting said finder circuit with said telephone line, means for connecting said finder circuit with said cord circuit, a sequence switchassociated with and controlling said cord circuit, means ac-' tuated 1n connectlng sa1d finder clrcul't with said cord circuit for moving said sequence switch out of its normal position, means for returning said sequence switch to normal, and means made operative by the return of said sequence switch for disconnecting said finder circuit from said cord circuit.

14. The combination with a calling telephone line, a connecting circuit, and a finder circuit uniting the same, of a sequence switch associated with said connecting circuit, means actuated by the completion of connection between said findercircuit and sa1d connecting c1rcu1t for'moving said sequence switch out of normal, a called telephone line, necting circuit with said called line, :1

means for connecting said conswitch operated in disconnecting said connecting circuit from said called line for returning said sequence switch to normal, and means actuated by the return to normal of said sequence switch for disconnecting said finder circuit from said calling line.-

' 15. The combination with a telephone line and a .connecting circuit, of a finder circuit for uniting the same, testing'mechanism responsive to the normal electrical condition of said connecting circuit, means controlled thereby for causing the finder circuit to make connection with said connecting circuit means for varying the electrical condition of said connecting circuit responsive to the establishment of connection therewith, means for reestablishing the normal electrical condition of said connecting circuit, and means made. operative by said testing mechanism upon the reestablishment of said normal electrical condition for efi'ecting the disconnection of said finder circuit from said telephone line.

1-6. The combination with a connecting circuit, of a finder circuit, an electromagnetic switch for establishing connection between said finder circuit and said connecting circuit, a test magnet controlling the operation of said switch, said test magnet being responsive to the normal electrical condition of said connecting circuit, means operating to Vary the electrical condition of said connecting circuit upon the establishment of connection therewith, means for re.-

' electromagnetic line-connecting switch, and

an electromagnetic cord-connecting switch,

means for varying the electrical condition of any of said lines and of any of said cords, a test magnet associated with said finder circuit, means controlledby said test magnet in response to the changed electrical condition of a line for causing said line-connecting switch to establish connection there- .with, means controlled by said test magnet in responseto the normal electrical condition of a cord for causing said cord-connecting switch to establish connection therewith and vary the electrical condition of the same, means'for reestablishing the normal electrical condition of the cord, and means controlled by said test magnet in response

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