US1498560A - Testing dsvice for telephone-exchange systems - Google Patents

Description

June 24 1924.

E. R. LUNDIUS TESTING DEVICE FOR TELEPHONE EXCHANGE SYSTEMS Filed DGC- 22, 1922 6 Sheets-Sheet l mmm. .QQ

1,498,560 E. R. LUNDIUS Filed nec. 22, 1922 s sheets-sheet 2j TESTING DEVICE FOR TELEPHONE EXCHANGE SYSTEMS June 24, 1924.

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TESTING DEVICE FOR TELEPHONE EXCHANGE SYSTEMS June 24 1924.

E. R. LUNDIUS TESTING DEVICE vFOR TELEPHONE EXCHANGE SYSTEMS June 24 1924.

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E. R. LUNDIUS TESTING DEVICE FOR TELEPHONE EXCHANGE SYSTEMS #Wen/an Y fr/k/lynaws rll June 24 1924.

E. R. LUNDIUS TESTING DEVICE FOR TELEPHONE EXCHANGE sYsTEMs Filed Dec. 22 35922 6 Sheets-Sheet 6 mmh Aff);

Patented June 24, 1924` UNITED STATES PATENT OFFICE.

ERIC R. LUNDIUS; OF BROOKLYN, NEN YORK, ASSIGNOR TO WESTERN ELECTRIC COM- PANY, INCORPORATED, OF NEVI YORK, N. Y., A CORPORATION OF NEW YORK.

TESTING DEVICE FOR TELEPHONE-EXCHANGE SYSTEMS.

Application filed December 22, 1922.

T all whom t 'may concern:

Be it known that I, Euro R. LUNDrUs, a citizen of the United States of America, residing at `Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Testing Devices for Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to a telephone exchange system, and more particularly, to a testing device for testing the selector switches employed in machine switching systems.

@ne of the principal requirements in the operation of a telephone exchange system operating either on a manual or mechanical basis, is that of maintaining the central ofceequipment in proper working condition. ln the case of manual exchanges the central oflice equipment is relatively simple and the problem of keeping such apparatus in good working order is a comparatively easy one. However in the case of mechanical offices, the central office equipment is much more complicated, the establishment of different classes of calls bringing into operation in varying combinations selector 'mechanisms of various types, each of which affords opportunities for trouble to arise. The amount of apparatus used in mechanical exchange systems is very large and much of it is made up of moving parts subject to loss of adjustment while in use or under repair. All apparatus of thisv nature, such as relays, interrupters, sequence switches, clutches and selector mechanisms must be watched to detect wear, or broken parts, or loss of adjustiuent which may be a result of a normal use of the equipment or the result of mistreatment. Naturally, the failure of any piece of apparatus to function properly will result in the stopping of the progress of calls or in the false routing of calls.

Such failures ordinarily would not be detected except where calls are repeatedly reported as incomplete, and such service interruptions, if frequent enough, would assume serious proportions from a service standpoint. It is, therefore, important that the apparatus of an exchange be regularly tested to determine, prior to its reported failure, if it is in suitable condition for rendering efficient service, or, after the apparatus has been withdrawn from service for repair or serial No. 608,430.

adjustment to determine if the repairs or adjustments which have been made, place the particular apparatus in serviceable ccndition. After the apparatus has been repaired or adjusted, it should be given vigorous and repeated tests under conditions simulating those under which it will function in actual service before it is again placed 1n service.

lt is, therefore, the object of this invention to provide a testing device for enabling tests to be made of the individual selector switches of a telephone exchange system.

More particularly, it is the object of this invention to provide a testing device for testing distant district selectors of the type disclosed in the Patent No. 1,439,735 to Edmund NV. Hancock, issued December 9.6, 1922, and oliice and final selectors of the type disclosed in the application of -Valter P. Albert No. 470,767, filed May i9, 1921.

lhile the invention has been disclosed as particularly adapted for testing switches of the panel type as disclosed in the aforesaid applications, it will be, however, ap` parent from the following description that the invention has a wider utility and that by slight modification it could be adapted for testing other types of selector switches.

A feature of the invention is the provision of means for operating switches einployed in the several selection stages of a mechanical switching system in simulation of the manner in which such switches function in actual service and for observing, through the medium of suitable supervisory apparatus, the accuracy with which the switches under test function.

A further feature of the invention relates to the p rovision of means for operating a selector switch in the establishment of all t-he different classes of connections for which such switch is designed.

A further feature of the invention. relates to the provision of means for adjusting a final selector switch for its ability to accurately function in testing lines of a private branch exchange group.

A further feature of the invention relates to the provision of means for conducting adjustment tests of various relays l belated with selector switch circuits.

These and other features of the invention will be apparent from the following description taken in connection with the accompanying drawings in which Figs. l, 2 and 3 show selector switches of the different selection stages of a mechanical exchange system upon which tests are to be conductedl and Figs. 4;, 5- and 6, taken together', disclose the circuits of a portable selector-switchtesting device. The drawings should be arranged for consideration with Figs. 1, 2 and 3 placed in the order named from left to right, Figs. 5 and 6v placed beneathv Figs. 1 and 2, respectively, and` Fig. 4L placed at the left of Fig. 5.

Fig. 1 shows the end of a trunk incoming to the exchange olce terminating in a district selector switchl and an auxiliary switch individualy to the district selector for associati-n'g an idle otiice sender therewith. An oliice sender is diagrammatically illustrated by the small rectangle in the lower right corner of the ligure designated Sendern Thel incoming end of the trunk is provided with alinake-busy jack which appears in the lower left corner of Fig. 2.

F-ig.- 2 shows an otlice selector which may be selected .by the district selector of Fig'. 1 and which has access to trunk lines leading tooutlying offices and directly to local final selectors, one of whichis disclosed in Fig. 3. Inthe lower portion of Fig. 2 jacks associated with the testing device of Figs. 4, 5

`and 6 and make-busy `jacks associated with the selector switches of Figs. 1, 2 and 3 together withpatching cords for interconnecting them, are disclosed.

Fig. 3 shows a local nal selector which hasaccess tolines of. a special character such as tielines to local operators positions and test lines. In the lower portion of this figure, mechanism common to a group of final selectors is illustrated, which functions to satisfy oiiice senders with respect to incomingbrushand group selection-s when the inalf switch is seized directly by the office selector of Fig. 2, without the interposition of anv incoming` selector'.

Fig. i shows the keyboard of a selector switch testing device.

Fig. 5` shows the counting relays of the testing. device and the auxiliary switch which functions to transmit relay call indicator code impulses when tests of the ollice selector of Fig. 2 are being conducted with relation to trunks extending to manual otiices.

Fig. 6 shows controlling keys and supervisory apparatus of the testing device together with an auxiliary switch for carrying tests through their various stages.

Description `of apparatus.

The automatic selector switches shown in Figs. 1, 2 and 3 are of the well-known power driven type in which a plurality of sets of brushes are mounted on a vertical brush shaft arranged to ybe lselectively tripped into final selectors 250 and 350, of Figs. 2 and 3v are described in the application of falter l). Albert, Serial No. 470,767 hereinbefore referred to.

The auxiliary switches 100, 110. 210, 310, 320, 510 and 610 are of the sequence switch type substantially similar in principle and construction to the one described in the patent to J. N. Reynolds and C. F. Baldwin, No. 1,127,808, issued February 9, 1915. regards switches 210 and 610, each of which appears on a separate sheet of the drawings, it may be noted that all cam contacts located on the same sheet with one of these switches are controlled thereby. In Fig. 1 switch 110 controls all cam contacts located within the dotted square, theremaining cam contacts of the figure being controlled by switch 100. In Fig. 3 switch 320 controls only the cam contacts located within the lower portion of the figure enclosed by the dotted lines, the remaining cam contacts being controlled by switch 310. In Fig. 5 cams 511, 512, 511i and 515 are controlled by switch 610 of Fig. 6, the remaining cams of the figure enclosed within the dotted lines being controlled by switch 510. i

Thetesting device disclosed in Figs. 1, 5.and 6 is enclosed in a portable box mounted upon rubber tired wheels for enabling it to be easily moved among the selector switch frames in the switching room of the office and is provided with suitable jacks, two of which are shown at 243 and 247 in Fig. 2 for connection, respectively, by patching cords to the make-busy jacks of the variousV selector switches of the oiiice and to the jacks of test lines. Other jacks shown in various portions of Fig. 6 are also provided on the portable boX for purposes which will be explained hereinafter. In actual practice power is transmitted to the testing device through jacks on the testing device which are patched by cord circuits to suitable power jacks on the selector switch frames. vSuch power connections include current supply for the direct cui'- rent motor 508 which drives the sequence switches 510 and 610, sources of 2li-volt and Li8-volt`current for operating the various relays of the testing device and ground potential. For convenience of illustration,

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however, these jacks have been omitted an/.l the sources of current and ground potential have heen shown directly associated with the different pieces of apparatus in Figs. 4 to 6, inclusive.

The keyboard of F ig. d comprises a plurality of rows of keys upon which the test man may record office and numeric-al designations of numbers with which it is de sired to test the various switchesof the exchange office. The keys of each row are locked when depressed under the control of the respective release magnets disclosed at the top of the figure.

The testing device is arranged to test three classes of switches as previously indicated, namely, district, office and final selectors, by three different methods at the option of the test man. According to the first method which will hereinafter be termed the step-by-step method, liey 011 is operated whereupon the test progresses only from one stage to another under the direct control of the test man through the repeated operation of the start key 007. Under this method the test man is enabled to closely observe the functioning of the selector under test. rllhe second testing method may be termed the continuous method as following the initial operation of the start key 007, the testing device proceeds through one complete ,y e i L forming the various tests requirec of the switch being tested and then automatically stops. Should a fault occur in the selector under test, the test is arrested immediately and an indication is given or" the particular stage in the test at which the fault ce curred. The third testing method will be referred to hereinafter as the exercise method. For this type of test the exercise key 027 is depressed and thereafter the test' ing device functions in the same manner as under the continuous method except that the test continues through any number of complete cycles until eiher stopped by fault in the selector under test or by the restoration of .the exercise ltey G27.

rlhe testing device may be used for male ing the following tests by any of the three methods outlined above:

1. Testing oilice and final selector switches together.

2. Testing the office selectors in eonjune tion with full mechanical trunks with the hey 628 operated.

3. rllesting ollice selectors in conjunction with relay call indicator trunks with the key G21 operated.

4e, Testing final selectors only with key 623 operated.

5 esting distant district selectors with key G12 operated.

Having now described in general way the apparatus employed in conducting 'tests and the manner in 'which it is to be used, it is thought that the invention will be bet ter understood from a consideration of the specific manner in which it functions. The testing device will, therefore, be first considered in connection with its operation in the conduct of a test on an office selector in conjunction with a final selector by the step-bystep method.

Testing m oy'ice selector n conjunction with a, inail selector 'stcp-bg/-stcp met/tod.

The test man before proceeding with the first test connects jack 2113 of the testing device by patching cord to the jack 238 which is connected to final multiples in the final selector witch 350, and connects ack 247 of the testing device by patching cord 24:8 with the maire busy jack 249 of the ofliice selector 250. lf the office selector is busy, a circuit is thereupon established from ground on conductor 241, from multiple 125 of a district selector which has seized the office selector, or from ground at cam 206 (2 to T), over sleeve ofjach 249, sleeve strand of cord 248, sleeve of jack 2e?, right contact of cam G00 (l), relay 601, upper left contact of cam (302 and to battery through the high resistance element. Relay 601 energizes in this circuit and closes a circuit for the busy lamp 003 which may be traced from battery through lamp 603, the upper right contact of cani 604i (1), the ripper left con tact of said can-'1 (1 to 15g), the armature and front contact of relay 601, conductor 005, outer right armature and back contact of relay 006 to ground. lVith relay 601 energized the test circuit may not be advanced by the operation of start hey 607, since the circuit from the start key 607 through the start relay S is opened at the miniature and bach contact of relay 601. Assuming that the otlice selector being tested is idle., then relay 601 does not energize and the selector is made busy from ground through low resistance element, the lower contact of cam 602 (l), the winning of relay 001, thence as Vtraced to conductor 2411 and the .multiple test 'terminals of all distant district selectors which have access thereto. As soon as sequence switch 6l() of the testing device leaves position 1, busy ground potential is supplied to the sleeve conductor 241,0ver the lower contact of cam 600 (1% to 18) and the upper right contact of cam 609 (lefA to 18).

Assuming that a step-by-step test is to be made the step-ey-step hey 611 and the ofiice to final hey 030 are depressed and locked in their depressed positions. Start key G07 is then operated and iinmedh ately released. Upon the operation of hey G07 a circuit is closed for start relay 608 as follows: battery, winding of relay G08, innermost right spring and normal contact of llt) the distant district key 612, inner right armature and back contact or relay 613, conductor 614, contact of key 607 left contacts of cam 615 (1), armature and back contact off relay 601, conductor 605to ground at the outer right arn'iature and back contact of relay 606. Relay 608 energizes in this circuit and closes a shunt around the winding of relay 617 extending through the armature and front contact of relay 608 to ground at the upper right contact of cam 616 (17 to 1). When the start key 607 is released, relay 611-7 energizes in series with relay 608 and closes a circuit for advancing sequence switch 610 out of position 1 into position 2, this circuit extending from battery through the magnet winding of switch 610, the lower right contact of cam 618 (17 to 1) tol groun'df at the armature and contact of relay 617'. As soon as the sequence switch 1eavesfposition1 the holding circuit of relays 608' and 617 is opened at cam 616 and these relays thereupon release. As the sequence switch enters position 1 a circuit is closed for relays 619l and 631 in series, which may betra'cedl from battery through the windings of' relays 631 and 619, the left contacts of camy 600 to ground at the upper right contact ocam 609 (19,; to 18).

With sequence switch 610 in position 2 a circuit is closed for the oiiice brush progress lamp 626' extending from battery through thislamp toground at the upper left contact of' cam 609 (2 to 3). A fundamental circuit is' also establishedv between the testing device and the oiice. selector' 250 which may be traced as follows: 'from ground at cam 202 (1vr to 4), conductor 240, ring or jack 249, ring strand of cord circuit 248, ring of j ack 247, conductor 252, resistance 632, upper right contact of cam 620 (2 to 4), innermost left spring andi normal contact of key 621, conductor 505, resistance 506 and the right winding of overflow relay 501 in parallel, windings of stepping relay 500, armature and back contact or' the No. 0 counting relay 503, conductor 507, upper contacts of cam 622', lef-t spring and normal contact of key 623, inner right spring and normal contact ofkey 621, lower right contact of cam 624 (2 to 4), resistance 633, conductor 625, normal contact of key ADJ, conductor 253, tip ory jack 247, tip strand of cord circuit 248, tip of jack 249, conductor 239, upper left Contact of cam 201 (1 to 4), lower left contact of cam 203 (1) to battery through the right winding of control relay 200. Relays 200 and 500-energize in this circuit, but overflowv relay 501 does not receive suihcient current to cause its energization at this time. Relay 200, upon energizing, closes a circuit extendingrom ground at its left armature and front contact, over the lower left contact ofcam 207 (1) and through the magnet windingl oii sequence switch 210 to battery for driving the sequence switch. out of po-V sition 1 into position 2. With relay 200energized and sequence switch 210 in position` 2, relay 200 is maintained energized over the fundamental circuit through its right armatures and iiront contacts and the lower right Contact o1l cam 203 (1 to 4) the initial energizing circuit or relay 200 being opened' at the lower left contact or cam 203 when; the sequence switch leaves position 1.

Upon the closure oit thefundamental eir-l cuit stepping relay 500 is operatedr and, as it will be assumed, that this test is beingl conducted with the No., 0 oiii'ce brush key 400 and the No. 1 oilice group key 401 d'epressed, a circuit is etsablished for the N o. 0 counting relay 502. This circuit may be traced from battery through the lower contact o1" cam 511 (2), throughthe winding of relay 502, the No. 0 lead 513, the No., 0' lead 403 Fig. 4, left contact or key 400, conductor 404, upper left contact of cam 514 v(2), conductor 516 and to groundV through the armature and contact or stepping relay 500. Relay 502 energizes and locks in series with the No. 0 counting relay 503', overA an circuit from battery at the lower contact of cam 511, windings oiz relays 502 and `503to ground at the armature and' contact of rev lay 502. Relay 503 does not, however, energize at this time since its winding is shunt` ed at the contact and armature oi` stepping relay 500.

At the oiiice selector 250, withl control relay 200 energizedV and sequence switch 210 in position 2, a circuit is established for theupdrive magnet 211l which mayl be traced from battery through the winding of mage net 211, right contacts of cam. 208 (2), to ground at the left armature and front contact or relay 200. Magnet 211, uponenelgizing, presses the depending portion of the switch shaft 214 against the constantly rotat-ing updrive drum 236 whereby the switch shaft and attached. brush sets are driven upwardly in a brush selection movement. As the shaft approaches its iirst brush selection position, the shaft wiper 218 engages a conducting portion of commutator 221 thereby closing a circuit in shunt of the stepping relay 500 which may beV traced from battery, through the right winding of relay 2007 right armatures and front contacts or said relay, right contacts of cam 203, commutator 221 tol ground at wiper 218. Upon the establishment of this shunt, stepping relay 500 deenergizes, but cont-rol relay 200 remains energized. Upon the. deenergization of relay 500 the shunt around the winding of relay 503 is opened and this relay energizes in the locking circuit of relay 502 a-nd opens the vfundamental circuit previously traced at its armature and. contact, whereupon, relay 200 deenergizes.

As soon following the opening of, the

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fundamental circuit as the shaft wiper 218 engages the next insulating` portion of commutator 221, the holding circuit of relay 200 is opened and this relay deenergizes, opening the previously traced circuit of the updrive magnet 211, thereby arresting the upward movement of the switch shaft. At its left armature and back contact, relay 200 establishes a circuit over the lower right contact of cam 207 and through the magnet` winding of sequence switch 210 to battery, for driving the sequence switch out of position 2 into position 3. At the time the No. 0 counting relay 503 operated, relay 504 energized in parallel therewith and es tablished a circuit from ground at its armature and contact, upper left contact of cam 649 (2), to battery through the magnet winding of sequence switch 610, for driving this sequence switch out of posit-ion 2 into position 3. As the sequence switch 610 leaves position 2 the looking circuit of counting relays 502 and 503 is opened at the lower contact of cam 511 and relays 502, 503 and 504 release.

VVit-h sequence switch 610 in position 3 the test man again operates the start lrey 607 closing a circuit for the start relay 608 which may be traced from battery through the winding of relay 608, the innermost right spring and normal contact of lrey 612, inner right armature and back contact of relay 613, conductor 614, contact of lrey 607 to ground at the upper right contact of cam 650 Relay 608 energizes in this circuit and locks in series with relay 617 as previously described. Relay 617 energizes as soon as lrcy 607 is released and closes a circuit over the lower right contact of cam 618 for advancing sequence switch 610 into position 4. As the sequence switch 610 leaves position 3 the circuit of the office brush progress lamp 626 is opened at the upper left contact of cam, 609 and when the sequence switch reaches position 4 a circuit is established for the oflice group progress lamp 651 which may be traced from battery through lamp 651 to ground at the lower right contact of cam 609 (4 to 5). vWith sequence switch 610 in position 4 a circuit is also closed from battery through the left winding of overflow relay 501 to ground at the lower left Contact of cam 616 (4 to 14), but due to the inclusion of resist ance in this circuit, relay 501 does not become energized.

The fundamental circuit previously traced through the windings of stepping relay 500. the right winding of overflow relay 501 and the winding of control relay 200 of the office selector is again established, relays 200 and 500 becoming energized, but overflow relay 501 remaining unoperated, since current flowing through its right winding is in opposition to the currentfiowing through its left winding. Relay 200, upon energizing over the fundamental circuit, closes a circuit from ground at its left armature and front contact, over the lower left contact of cam 207 for advancing sequence switch 210 into position 4. After the sequence switch 210 leaves position 3 relay 200 is maintained energized over the fundamental circuit through its right armatures and front contacts and the lower right Contact of cam 203 (1 to 4). )Vith relay 200 energized and sequence switch 210 in position 4 the circuit of the updrive magnet 211 is again established and the switch shaft is again driven upwardly. During the first portion of its upward move ment the first" set of brushes is tripped in the wellsknown manner through the operation of tripping magnet 213 which was energized over the lower contact of cam 206 (3 to 7) as soon as sequence switch 210 reached position 3. As the switch shaft continues in its upward movement the tripped set of brushes is moved adjacent the first group of terminals in the terminal bank and a circuit is closed in shunt of the winding of stepping relay 500 which may be traced from battery, winding of relay 200, right armatures and front contacts of relay 200, the lower right and upper left contacts of cam 203, commutator 222 to ground at shaft wiper 218. Relay 500 thereupon deenergizes, relay 200, however, remaining energized over the above traced shunt path.

At the testing device upon the energization of relay 500, with sequence switch 610 in position 4, a circuit is established for the No. 1 counting relay 517 extending from battery, through the upper right contact of cam 512 (4), winding' of the No. 1 counting" relay 517, armature and baclr contact of the No. 1 counting relay 518, lead 519, lead 402 Fi 4, alternate contacts of lrey 401, conductor 405, upper right contact of cam 514 (4), conductor 516 to ground through the armature and contact of stepping relay 500. Relay 517, upon energizing, locks in series with relay 518 to ground at the armature and contact of relay 517, but relay 518 does not energize until relay 500 deenergizes upon the initial establishment of the shunt about its winding at commutator 222 of the oiiice selector. Upon the first deenergization of relay 500, relay 518 energizes extending the lead 519 through the armature and front contact of relay 518 through the winding of the No. 0 relay 502 to battery at the lower contact of cam511 (4). As the switch shaft 214 of the oiiice selector 250 continues in its group selection movement, the shaft wiper 218 engages the next insulating portion of commutator 222 thereby opening the shunt around relay 500 again permitting its energization. The circuit for the No. 0 countins relay 502 is new @saarland at the arma .sequence switch 210 into position 5.

Ecam 205.

yin, .circuitsfof'the energized countinoa rela s are .opened and such relays release, and the circuit previously traced through the wind- .ings of .relays 6.19 and 631 is also opened at the upper left contact of cam 60.0. Relay 6129, upon deenergizing, ,places shunts around the resistance elements 632 and 6.33 which have up to lthis time been included .in the fundamental circuit hereinb'efore traced.

Aft the office selector as soon following the opening vof the fundamental circuit Aas lthe wiper 218 engages the nent insulating portion of commutator 222, relay 200 deenergizes opening the circuit 4of ythe updrive mag- -net .2f11 and closing a circuit over its left armature and vback Contact and the `lower right contact of/cam 207 for advancing With sequence switch 2.10 in position 5 .a circuit is established from battery through the4 left winding of Arelay 200 to ground, through the Aleft contacts Aof cam i209. Relay 200, upon energizing in 'this circuit, `establishes a circuit over ,its left armature and front contact l*for driving sequence switch 210 out of position 5 into position 6. When sequence switch 2.10 leaves position v5 vthe circuit'jlust.

'traced `for. relay 200 is vopened Aat contacts of cam 209 and, as lit will be assumed that the first trunk of the group upon which the brushes of the selector are standing is idle,

there is no locking circuit for relay `200 over test. brush 217 and the upper contacts of Relay 200, therefore, deenergizes `as soon as :sequence switch 210 leaves position 5 without causing the advance Vof the switch shaft y214 in its vhunting movement,

and at its left armature and back .contact closes lthe circuit for advancing sequence switch '210 into .position In `positionl? Arelay i200 again ener-gizes over its left wind ing and the left contacts of cam 209 vcausing the advance of sequence switch .210 :intothe vtalking position 8. Relay 200 now establishes ya lockingci-rcuit for itself extending from Abattery through its .right winding `right armatures and' front contacts, the left Y contacts of cam 205eonductor 24l,sleev e of jack `249, .sleeve Y,stra-'nd of cor-d :circuit 248,

sleeve of jack/:247, the lower contacto cam l600V (1:5- to 18) ,to,ground,at the upper right contact of cam 609 (1% to 18) and is thus maintained energized until the test of selec- v Y tors 250 and 350 is completed. The Afinal trunk selected by switcli 250 is maintained busy by ground potential connected to the multiples of terminal 229, `over brush 217 and the right contact ofvcam 206.

)Vith the sequence switch 610 of thc testing .device in position 5 and the oiiice selector sequence switch 210 in position 8, a circuit is established for relay 652 which may ybe traced from battery, through the wind- Vingof control relay 300 of the final selector, the left contacts of cam 316, the upper left contact of cam 306 (1 to 10) the lower right contact of cam 305 (1 to 15), resistance 330, conductor 232, bank terminal 227 and brush 215 of yoflice selector 250, Athe upper contacts of cam 201 (8), conductor 239, tip 4of jack 249, tip strand of cord circuit 248, Jtip of jack 247, conductor 253, normal conftactof key ADJ, conductor 625, intermediate .armature and Aback contact of relay 619. lower left contact of cam 624 (5), 16,000 ohm resistances 680 and 676 Winding of relay`652, upper left contact of cam 620 (5 to 6), the lower armature and back contact of relay 619, conductor 252, ring of jack 247, ring strand of cord circuit 248, ring of jack 249, conductor 240, upper `contacts of cam 204 (8), brush .216 and bank terminal 228 of otiice selector 250, conductor 233, resistance 332 .to ground at the upper contacts of cam 317. Relay 652 receivessuiiicient current in this `circuit to operate if the trunk is found to be in .proper condition, but due to the inclusionof the 16,000 ohm resistances at the testing device, the cont-rol relay 300 of the filial selector does notoperate. Relay I652, upon energizing, closes `an obvious cir- 'cuit for relay 637 which at its right armature and front contact establishes a circuit over the upper right Contact of cam 653 and through the `magnet winding of sequence switch 610 fto battery for driving tho sequence switch into position l6. As soon as thesequence switch 610 leaves position 5 the circuit of thc oflice group progress lamp y651 opened at the lower right contact of cam v609 4 to 5) indicating` vthat office group selection has .been successfully completed, and at the lower left contact of cam 624 opens the circuit of relay 652, which in turn, opens the circuit of relay 637. )Vith sequence switch 610 in position 6, the circuit 'of-the incoming brush progress lamp 654 is closed over the lower left contact of cam 609 to 7). As no incoming selectors are employed,

v'the incoming brush and group select-ions are taken care of in the final selector 350. The

`incoming selections being always No. 0

.through the windings of stepping relay500 and the winding of control relay 300 oft-h6 i Y final selector, which may be trac-ed from battery through the winding of relay 300, thence as previously traced to conductor 625, the intermediate armature and back contact of relay 619, the lower right contact of cam 621i (6 to 1st), the inner right spring and normal contact of key 621, the left spring and normal contact of key 623, the upper contacts of cam 622, conductor 507, the armature and back contact of the No. 0' counting relay 503, the windings of stepping relay 500, resistance 506 and the right winding of overflow relay 501 in parallel, conductor 505, the inner left spring and normal contact of key 621, the upper right contact of. cam 620, the lower armature and back contact of relay 619, conductor 252, thence as previously traced to ground at the upper contacts of cam 317. Relays 300 and 500 energize in this circuit, relay 500 closing a circuit for the No. 0 counting relay 502 which may be traced from battery through the lower contact of cam 511 (6), winding of counting relay 502, lead 513, the No. 0 lead at the innermost left spring and normal contact of key 628, conductor 520, lower left contact of cam 51-1 (6), conductor 516 to ground at the armature and contact of relay 500. Relay 502 locks in series with relay 503 but the latter relay being shunted at the armature and contact of stepping relay 500 does not energize at this time.

At the filial selector 350 upon the energization of relay 300 a circuit is established from ground at the right armature and front contact of this relay, over the upper right contact of cam 312 (1) and to battery through the magnet winding of sequence switch 310 for advancing this sequence switch out of position 1 into position 2. After sequence switch 310 leaves position 1 relay 300 maintains itself locked to the fundamental circuit over its left armature and front contact. Immediately that sequence switch 310 reaches position on its way to position 2 a circuit is closed from battery through the winding of sequence switch magnet 820, contact of cam 321 (1), lower left contact of cam 311 (1 to ll), lower right contact of said cam (1% to 14) to ground. Sequence switch 320 which is common to all final selector switches, energizes and rotates through a complete cycle for the purpose of sending impulses hack to the testing device to satisfy any registrations which have been recorded on the keyboard thereof and which normally serve to control incoming brush and incoming` group selections. During the rotation of switch 320 from position 1 through its complete cycle into position 1 again, the upper right contact of cani 3511 is closed in the successive positions 2 to 18. At each of these closures the following circuit is momentarily established fromkbattery, winding and front contact and left armature of relay 300, upper left contact of cani 306 (1to10) lower right contact of cam 305 (1 to 15), resistance 330, contact of cani 308 (1.13,- to 2) to ground through cam 354. rllhis circuit maintains the energization of control relay 300 but shunts down stepping relay 500 of the testing device. Since as herein assumed the No. 0 counting relay 502 was energized by the energization of relay 500, the first deenergization of relay 500 upon the first closure of cam contact 3511 in position 2 will permit the energization of relays 503 and 504i in series with relay 502. Relay 503 now opens the fundamental circuit cansing the release of relays 300 and 500, and relay 501i closes the previously traced circuit for advancing sequence switch 610 of the testing' device out of position 6 into position 7. Sequence switch 610 upon leaving position 6 opens the holding circuit of relays 502, 503 and 504 which thereupon release. Rel ay 300 of the final selector, upon deenergizing, closes a circuit which extends from battery through the winding of sequence switch magnet 310, upper left contact of cam 312 (2), the right armature and back contact of relay 300, to ground for drivl ig sequence switch 310 into position 3.

lilith sequence switch 610 in position 7, the test man again operates the start key 607 whereupon start relays 608 and 617 function over the circuit previously traced for driving sequence switch 610 out of position 7 into position 8. )When sequence switch 610 leaves position 7 the circuit of the incoming brush progress lamp 654e is opened at the lower left contact of cam 609 (6 to 7), indicating that no fault has occurred in making incoming brush selection, and the holding circuit of relays 606 and 617 is opened at the upper right contact of cam 616 lVhen switch 610 reaches position 6 the circuit of in coming group progress lamp 655 is closed over the upper left contact of cam 659 (8 to 9). llvith the sequence switch 610 in position 8 and sequence switch 310 of the final selector in position 3, the fundamental circuit previously traced through the windings of relays 500 and 300 is again established, relay 500 again closing the circuit of the No. 0 counting relay 502 from battery, lower contact of cam 511 (8), winding of relay 502, lead No. 0 lead at the innermost right spring` and norma1 contact of key 628, conductor 521. the lower right contact of. cam 514i-, conductor 516 to ground at the armature and contact of relay 500. Relay 502, upon energizing, locks in series with relays 503 and 504, but the latter relays do not energize at this time since they are shunted at the armature and contact of relay 500.

At the final selector upon the energization of relay 300,y the previously traced circuit is closed for advancing sequence switch '310 out of position 3 into position 4. After sequence switch 310 leaves position 3, relay 300 maintains itself connected to the fundamental circuit over its left armature and 'front contact. lf at this time sequence switch 320 has not completed its first cycle, `the .remaining .positions of this switch will be utilized in sending back impulses to the testing device to satisfy the registration 4thereat which normally controls incoming group selection. 0n the other hand, if the sequence switch 320 has already reached its normal position, or if it reaches the end of .its rst cycle prior to the time the proper lnumber of .impulses have been reverted to the ytesting device, it will be driven through Aa second cycle by means of the circuit previously traced through the contact of sequence switch cam 321 and the 'lower con.-

in position 4 successive closures of sequence switch cam 354 momentarily complete the following circuit for relay 300 in shunt of vthe windings of relay 500: battery, winding and front'contact and left armature of relay '300, -upper left contact of cam 306 (1 to 10), .the lower right contact of cam 305 (1 to 15), .resistance 330, contact ofvcam 303 (35i to 4), thence through the upper right contact of cam 354 vto ground. Upon the iirst closure of cam 354 following the energization of relay300 for controlling incoming group selection, since the No. 0 counting relay 502 is at the time energized, relay 500 will release Aand permit the energization of relays 503 and 504. Relay 503, upon energizing, opensthe fundamental circuit and relay 504 closes the previously traced circuit for advancing sequence switch 610 out of position V8 into position 9. Sequence switch 610, upon 'leaving `'position 8, opens the locking circuit of relays 502, 503 and 504 whereupon they release. Relay 300 of the linal selector, upon releasing,closes a circuit over its right armature and back contact and the upper left contact of cam 312 (4) for driving sequence switch 310 out of position 4 into position 5. VVh/en' following this thesequence switch 320 `reaches position 1, it comes to rest in as '50 @much fas its operating circuit is now open at the lower left contact of cam 311 (1 to 4).

With sequence switch 510 in position 9 the 'test man again `operates the start key 607 whereupon relays 608 and 617 function as before described for driving sequence switch r610 'out of position "9 into position 10. lilhen sequence-switch 610 leaves position 9 the cir- .cuit of incoming group lprogress lamp 655 is opened, and when the switch reaches posi- -tion 10 a ycircuit is closed over the upper right contact lof cam 659 (10 to 11) for the final brush progress lamp 656. The extinguishing of 'la-mp 655 indicates that no fault has 'occurred in making incoming group selectien.,

etacts-of cam 311. l/Vith sequence switch 310y With sequence switch 610 in position 10 and sequence switch 310 of the final selector in position 5, the previously traced fundamental circuit through the windings of relay 500 and the winding of relay 300 is again established, relays 300 and 500 becoming energized. lt will now be assumed that to select the test line 344, 345, 346, appearing in the bank of selector 350 on terminals No. 9i' in the `first brush group, tne test man has depressed the No. 0 hundreds key 405, the No. 9 tens key 407 and the No. 7 units key Relay 500, upon energizing, establishes a circuit from battery, the lower contact of cam 511 (10), the winding of counting relay 502, the No. 0 lead 513, the No. 0 lead 409 Fig. 4, the right contact of key 406, conductor 410, lower left contact of cam 515 (10), conductor 516 to ground at the armature and contact of relay 500. The relay 502 ener- `gizes in this circuit locking through the winding of relays 503 and 504 in parallel. Relays 503 and 504 do not Venergize at this time, however, since they are shunted at the armature and contact of relay 500.

At the 4final selector upon the energization of relay 300 over the fundamental circuit, relay 300 closes a holding circuit for itself over its left armature and front contact and establishes a circuit from battery, winding of sequence switch magnet 310, upper right contact of cam 312 (5), front contact -and right armature of relay 300 to ground, driving sequence switch 310 out of position 5 into position 6. In position 6 a circuit is closed for the high speed updrive magnet 333 traceable from battery through the winding of said magnet, right contact of cam 319 (6), upper left contact of cam 315 to 6), front contact and right armature of relay 300 Ato ground. Magnet 333, upon energizing, )resses the depending portion of switch shaft 337 against the updrive drum 361 vwhereupon the switch shaft yis driven upwardly to select the proper set of brushes. As the switch shaft reaches its first brush select-ion position, a circuit is closed in shunt of the windings of stepping relay `500 from battery, winding, left armature and front contact of relay 300, upper left contact of cam 306 (1 to 10), upper right contact of cam 305 to 5), coinmutator 350, brush 348 to ground. This circuit holds relay 300 energized and causes the deenergization of relay 500, which by removing the shunt from relay 503 permits the energization of relay 503 in series with relay 502. Relay 504 now energizes vin parallel with relay 503.

Relay 503, upon energizing, opens the fun- -r damental circuit through the windings of relays 500 and 300 and relay 504 closes the previously traced circuit extending over the upper left contact of cam G49 for driving sequence switch 610 out `of position 10 into position 11. Sequence switch 610, upon-` leaving position 10, opens the locking circuit of relays 502, 503 and 504. As soon following the opening of the fundamental circuit as the shaft wiper engages the next insulating portion of coininu'tator 300, the control relay 300 becomes deenergized and opens the circuit of the updrive magnet 333. Relay 300 also completes a circuit from battery through the winding of sequence switch niagnet 310, the upper left contact of cam 312 (6), back contact and right armature of relay 300 to ground for driving sequence vitch 310 into position 7. ln this position a circuit is established from battery, through the winding of trip magnet 330, the lower right contact of cam 313 (7 to 3), upper right contact of said cam (1 to 15) to ground. Magnet 336 now operates and prepares for tripping the selected set of brushes at the nent upward movement of the switch shaft lilith sequence switch 610 in position 11 the test man again operates the start key 607, whereupon relays G03 and 617 function as before described for driving sequence, switch G10 out of position 11 and into position 12. When sequence switch 010 leaves position 11 the holding circuit of relays G03 and 617 is opened and the circuit previously traced for the final brush progress lamp 650 is also opened indicating that no fault has occurred in making final brush selection. Niii/Then sequence switch G10 reaches position 12 the circuit for the final tens progress lamp 057 is established. from battery through lamp 357 to ground at the lower rigliit contact of cani 659 (12 to 13).

With sequence switch 610 in position 12 and sequence switch 310 of the final selector 350 in position 7, the fundamental circuit previously traced is again established and relays 300 and 500 operate. Relay 500 upon operating now closes a circuitfor the No. 9 counting relay 522, it having been assumed that the No. 9 tens key 407 was depressed. This circuit is as follows: battery, lower contact ofl cani 511 (12), the No. 9 relay 522, armature and bach contact of No. 9 counting relay 523, lead 524, lead L111 Fig. 11, the left contact of ltey -1-07, conductor 112, right contact of cani 515 (12), conductor 516 to ground at the armature and contact of relay 500. Relay 522 energizes in this circuit and locks in series with relay 523. Relay 523 being shunted at the armature and contact of relay 500 does not energize at this time.

At the final selector upon the energization of relay 300 over the fundamental circuit, the relay 300 closes a holding circuit foi itself and also completes a circuit from battery through the winding of sequence switch magnet 310, upper right contact of cam 312 (7), front contact and right armature of relay 300 to ground. Sequence switch 310 is now driven from position 7 into position 3 where a circuit is closed from battery through winding of high speed updrive magnet 333, right contact of cam 319 (8), upper left contact of cam 315 (7-1- to 8), front contact and right armature of relay 300 to ground. Magnet 333, upon energizing, presses the depending portion of switch shaft 337 against the drum 351, whereupon the switch shaft is driven upwardly and the selected set of brushes 338, 339 and 340 are tripped and moved over the terminals of the portion of the banlz to which they are allotted. As the switch. shaft moves upwardly and approaches each group selection position, the shaft wiper 3417 engages a metallic portion of the commntator 352 and the following circuit is momentarily established in shunt of the stepping` relay 500: battery, winding left armature and front contact of relay 300, upper left contact of cam 306 (1 to 10) lower right contact of cam 306 (T- to 3), coininutator 352, wiper 347, to ground. This circuit holds relay 300 energized, but shunts down stepping relay 500, which permits the successive operation of counting relays beginning with the No. 9 counting relay 523 until the No. 0 counting relay 503 energizes, at which time the brush shaft will have positioned the brushes 333, 339 and 3110 beneath the tenth group of bank te minals Relay 503 upon energizing in parallel with relay -1, opens the fundamental circuit and relay 504- establishes the previously traced circuit over the upper left contact of cam 649 (12) for advancing sequence switch 610 into position 13. Sequence switch 610 upon leaving position 12 opens the locking circuits of all oper= ated counting relays at contacts of cams 511 and 512.

At the final selector switch and as soon following the opening of the fundamental circuit by the counting relay 503 as the shaft wiper 347 engages the next insulating portion of commutator 352, relay 300 becomes deenergized and opens the circuitl of updrive magnet causing the switch shaft to cease its upward moven'ient. Relay 300 also establishes a circuit from battery through the winding of sequence switch magnet 310, upper left contact of cam 312 (3), back contact and right armature of relay 300 to ground, for adi'ff'ancing said sequence switch into position 9.

l/fith sequence switch 610 of the testing device in position 13 the test man again operates the start lrey G0@l whereupon relays 608 and 617 function as before described to advance sequence switch 610 into position 14. lWhen sequence switch 610 leaves position 13 the holding circuit of relays 608 and 617 is opened and the circuit of the final tens progress lamp 657 is also opened at the lower right contact of cam 659. )Vith sequence The extinguishing of `lan'ip 657 indicates to the test man that no fault has occurred in making linal tens selection.

With sequence switch 610 in position 14 and sequence switch 300 ol the final selector 350 in position 9, the fundamental circuit previously traced is again established and relays 300 and 500l operate. Relay 500, upon operating, now closes a circuit for the No. 7 counting relay 526, it having been assumed that the No. 7 units key 403 was depressed.. This circuit may be traced from battery, lower contact of cam 511 (14), winding of relay 526, armature and back contact of relay 527, No.v 7 lead 523, No. 7 lead 413 lig. 4, left contact ot key 408, conductor 414, upper contact oif cam 515 (14), conductor 516 to ground at the armature and contact of relay 500, Relay 526 energizes in this circuit and locks in series 'with relay 527. Rel-ay 527, however, does not energize at this time as it is shunted at the armature and contact of relay 500.

At the final selector, relay 300 upon energizing over the` fundamental circuit, closes a holding circuit 'for itself and completes a circuit from battery through the winding of sequence switchmagnet 310,y upper right contact of cam 312 (9), liront contact and right armature ot relay 300 to ground, driving sequence switch 310 out oi position 9 into position 10. ln this position a circuit is closed from battery through the wind-- ing of the'l low speed updrive magnet 334, left contact of cam 319 (10), upper leift contact of cam 315 to- 10), 'liront contact and righ-t armature of relay 300 to ground. Mag net 334,` upon energizing, presses the depending portion oi' switch shaft against: lthe drum. 362 whereupon the switch shalt is` driven upwardly at a low rate ol speed. As the switch s'ha'tft moves the selected brushes 333,I 339 and 340 over each set o'l' terminal-s in the selected group, the shaft wiper 343 engages a conducting portion of the con'imutator 3607 momentarily closing a shunt around the windings oi' stepping relay 500 which may be traced as follows: battery, winding left armature and iront contact oi relay 300, upper left contact of cam 306 (1 to 10),` upper right contact of cam 305 to 10) ,i commutator 360 to ground at wiper 343. Relay 300 is maintained in this circuit, but relay 500 deenergizes cach time the circuit is es tablished whereupon' the countingrelays beginning with relay 527 are operated in succession until thc No. 0 counting relay 503 operates in parallel with relay 504. Relay 503, upon operating, opens the fundamental 4relay 302 to cause its energization. `302, upon operating, closes a circuit from circuit and relay 504 closes the previously traced circuit for advancing sequence switch 610 out of position 14 into position 15. When sequence switch 610 leaves position 14 the holding circuits oi the operated counting relays are opened at the contacts of cams 511 and 512.

lith sequence switch 610 in position 15 a circuit is closed for lamp 661 which may be traced from battery th-rough lamp 661, the inner right spring and normal contact of the make-busy key, the outer right armature and back contact oli relay 640 to ground at the upper left contact of. cam 650 (15). A circuit is also closed from battery through supervisory lamp 662, the armature and back contact of relay 663, the armature and back contact of relay 635 to ground through the lower contact of cam 616 (15 to 17). The lighting of these lamps at this time is an indication that selections have all been completed.

At the final selector following the completion of units selection, relay 300 deenergizes as soon 'following the opening of the fundamentalcirouit as the brushes 338, 339 and 340 are accurately centered on the terminals 341, 342 and 343, at which time, wiper 343 engages an insulating portion of commutator 360. Relay 300,` upon deencrgizing, opens the circuit of updrive magnet 334 causing the switch shaft to cease its upward' movement and completes a circuit from battery through the winding of sequence switch magnet 310,y upper left contact of cam 312 (10), back contact and right armature ol relay V300 to ground. for driving said sequence switch out of position 10 into position 11.

A testV isnow made to determine the busy or idle condition of test line 344, 345 and 346 upon which the brushes ol the iinal selector switch have beenset. Since the make busy key of the testing device is in its normal position, the test line will test idle and the test circuit n'iay, therefore, be traced :from battery, righ-t winding oi relay 302', lower left and upper right contacts ot cam 314 (.11 to 13), left winding oi relay 302, lower contact of cam 329 (11 to 163,-), brush 340, terminal 343, conductors 346 and 235, sleeve oft' jack 238, sleeve strand oil cord circuit 242,- sleeve ot ack 243,l inner left spring and normal contact of n'iake-busy key, right contacts of cam 615 2 to 18), winding of relay 601, upper right contact of cam 602 (2 to 18), resistance 664,. to ground at the normal con-tact of key l). B. Due to the full ground potential on terminal 343, sullicient current flows through the windings ol' Relay battery, through its lelit armature and front contact, left winding. olf said relay, lower contact olE cam 329 (.11 to 164),4 brush 340 to the test terminal 343 and also to the mulltiples thereof in: other switches. The re Cir sistance of this circuit through the left winding of relay 302 is low and therefore reduces the potential. on the multiples of test terininal 3413 to a point where relays 302 of other switches cannot operate when a test is inade thereby, inalring the test line nonselcctable to other switches. Relay 302 also completes a circuit 'from ground through its right arinature and iront contact, lower left contact ol2 cani 312 (11), winding oi` sequence switch magnet 310 to battery for driving the sequence switch out of position 11 into position 13. ln positions 12 and 13 a circuit is closed over the right winding of relay 301 and contacts of cani 317, but relay 301 does not receive suilicient current to energize at this tiine. lin position 13 a circuit is closed 'troni battery through the winding of sequence switch niagnet 310, upper left contact oir cani 312 (13), back contact and right armature o1Ll relay 300 to ground for driving sequence switch 310 into position 14C. In position 14 relay 300 is energized by ineans of a circuit iiroin battery through the winding of said relay, lower lett contact of cani 316 (1 to 141), upper lett contact ot' cani 316 (111), upper right contact of cani 311 (111 to 1S), lower right contact ot said cani (lil to 14;), to ground. Relay 300 completes a circuit from battery through the winding of sequence switch magnet 310, upper right contact or" cain 312 (111), front contact and right armature of relay 300 to ground, driving sequence switch 310 into position 15. Gn leaving position 1l sequence switch 31() opens the lett contacts of cani 316, but relay 300 remains actuated in a circuit frein battery through the winding of said relay, its vfront contact and lett armature, upper right contact of cani 311 (1/1 to 18), upper left contact of said cani (2 to 13), conductor 2511, contacts 245 associated with jaclr 244i, conductor 234, terininal 229, brush 217 of office selector 250, upper right contact ot cani G (612; to 8;]1) to ground. 1n position 15 of sequence switch 310 a circuit is closed ironi battery through the. winding of sequence switch inagnet 310, lower lett contact of cain 312 (15), front contact and right armature of relay 302 to ground for advancing sequence switch 31() into the talking position 16.

At the testing device it there was no fault in the sleeve circuit ot the iinal selector, relay 601 energized in the circuit traced through the windings of the test relay 302, and upon energizing, established a circuit from battery through the winding ot relay 640, lower right and upper lett contacts of cani 604-, armature and front contact of relay 601, conductor 605 to ground at the outer right armature and back contact of relay 606. The operation or' relay 611() now opens the circuit previously traced for sleeve lainp 661 and opens at its lett armature and back '219, ring strand of cord 248, ring contact the operating 63'.

At the iinal selector while its sequence switch 310 was still in the testing position 11, a circuit was also closed for operating supervisory relays (334- and 663 oi the testing device. ll' the circuit to operate these relays is closed prior to the circuit previously traced for relay G01, it may be traced as follows: battery, lower lett and upper' right contacts ot cani S) (11 to 15), resistance 331, conductor 233, terniinal 223 and brush 216 oit otllce selector 250, the upper contacts of cam 2041 (3), conductor 210, ri ot acl; y oil jack 2117, conductor 252, lower arniature and back contact oit relay G19, lower contact et rain G20 (15 to 17), lower left winding of repeating coil 653, lower winding ot relay 534, lower armature and back contact or relay 631, winding oiPV poiariae,1 relay 363, intermediate armature and back contact ot relay 831, upper winding of relay 534i, upper lett winding ot repeating coil 653, upper contact oif cani 524; (15), intermediate armature and haelt contact oil relay 619, conductor (3253, normal contact ol' ADJ, conductor 253, tip of jack 2li?, tip strand ot cord 24.3, tip ot jack 249, conductor 239, ripper contacts oit cani 201 (3), brush 215 and terminal 22?y ot oilice selector 250, conductor 232, resistance 330, lower right and upper left contacts of cani 305 (11 to 15) to ground. rlhe direction ot current flowing `in this circuit is such as to operate both relay 634 and polarized relay 663. Relay 663, upon operating, now opens at its armature and back contact the circuit et supervisory lainp G62. Relay 634.-, upon operating, clos-es a circuit for relay 639, it being previously assuined that relays 601 and 6410 have not yet operated. The circuit of relay 639 n'iay be traced from battery, relay circuit for relay lrey co9, lelt armature and back contact of relay 610 to ground at the armature and 'front contact of' relay G3i. Relay 639, upon operating, locks through its right are rnature and front contact to ground at the lower right contact of cani 613 (15 to 17) and at its lett armature and bacl; contact opens the circuit previously traced iter lainp 665 preventing it from lighting when the relay 64:0 later operates.

lilfhen now the relay G4() ope-rates in the manner previously described, sequence switch 610 is advanced out ot' position 15 into position 16 over a circuitliroin battery magnet winding et sequence switch 610, lower right contact et cani G53 (15), lett arinature and front contact of relay 639, conductor (377, to ground at the inner right armature and front Contact oit relay (3410. Vith relay 6l() operated the lanip G61 is extinguished as previously described, indicating no -fault in the sleeve circuits of the final selector.

Cil

When the sequence switch 310 leaves position 15 the circuit previously traced for relays (i3/l: and (S63 is opened at cani 624iand these relaysI release, relighting the supervisory lainp G62. The ligliting oi this lainp at this tiine is without ,function and may be disregarded by the test-nien. As sequence switch G leaves position 15 ythe circuit ot iinal units progress lanip G58 iis open at the lower lett contact et' cani 659 (14 to 15), indicating that no fault has occurred in making' units selection. Should relays 601 and 6410 iail yto operate the sequence switch (S10 will not advance and the lainp 661 Will, therefore, rcniain lighted and relays (334i and 663 will reinain energized. When sequence switch 610 reaches position 16, relays (33% and 663 reoperate eXtinguishingI lanip 662.

Should the circuits tor operating` relays (i3-l and G01 be closed siinultaneously with sequence switch 31() ot the linal selector in position 11, the relay 684e will operate and close a circuit from ground at its arinature and trent Contact, the lett armature and back contact ot relay Gli), to battery through the winding oi relay G39 which then locks to ground at the lower right contant ou cani G16 (15 to 17). Relay (510, which is energized upon the. operation ot relay 601, is slow to operate, while relay 689 is 'fast to operate, therefore, relay has suliicient time to operate and lock be'lore relay 64C() operates and opens its circuit. viWith relay (S39 operated, lainp G65 cannot lig-ht and se quence switch 610 is advanced to position 1G as soon as relay (310 operates, the circuits vthen functioning as above described. Illhe. 'relay 61110 .is inade sloW-to-operatc to alloiv for sliglit inaccuracies in the cutting oi cains 309 and 317 ot the linal circuit.

Y Should the circuit to operate relay (301 be closed beitore the circuit to operate relay 684iis closed, relay 601 will operate relay Geil), in turn preventingv the operation ot relay 639 `when relay 634; later operates.

Since relay G-l-O is norv energized and relay G39 is not-operated, circuit is closed for the lamp (S65, through the lett contacts of' cani G67, lett armature and back contact ot relay G39 to ground at the inner right armature and iront contact ot relay (ii-l0. The extinguishing of lamp (SG1 indicates that no 'fault exists onl the sleeve circuit ot the final selector'. Under this condition the testing,` sequence switch G10 remains in position as there is no circuit closed by relay 639 for driving it into position 1G. It the lainp G65 remains lighted at this time, it will indicate` to the test-man trouble in the talking conductors of the final selector as `will hereinafter be described.

It the sequence switch 610 remains in position 15 and lamp G65 remains lighted after relays 601 and (iv/l0 have operated, it indicates to the test-Inanthat a fault has oc-l curred at either or both of the canis 309 and 31? of the final circuit. li, however, with sequence switch G10 in position 15, earns 309 and 31T supply battery and zground potential' properly, relays (331i and 663 operate as above described and sequence switch 610 is advanced into position 1G Where it awaits the closure of the talking circuit at the final lector. TWhen the final selector' finishes testing and the sequence switch 310 thereof nieves into the talkingpostion 16, the circuit oi relays 634 and 66B above traced is changed, conductor 232 in such circuit being disconnected from battery at the lower contact of cani 309 and connected over thelower left contact of cam 305 (16 to 17), thev lower lett contact of cani 306 (16), brush 3238, terminal 341, conductor 344, conductor' 230, tip of? jack 23S, tip strand of cord 242', tip oi' jack 243 to ground at the lett normal contacts of relay 645, and conductor 233 inl the circuit oi relays (S3-l: and 6G3- i's then disconnected troni ground at the upper contact ot cani 2317 and connected' over theI upper contact ot cani 307 (1G), brush 339,-ter1ninal 3412, conductor 3115, conductor 231, ring ot jack 23S, ring` strand of cord 242, ring ot jack 243, norinal contacts of the right armature of relay G/lto battery throughv the lett wiiiding oi relay (3%3. Polarized relay G63 now releases as' the current flowing; through its Winding is reversed and' super? visory lainp 662 is noW permitted to rclight. Relays 634i and 643, however, are energized in this circuit.

lf an open circuit should occur in the iinall at canas 305, G or 307, or at the brushes 38S and 339, or the tip side oi the final eircuit be grounded, or the tip and ring sides be short circuited, relay G34- will not remain operated and upon its deenergization Will close the circuit ot lamp 666 troni battery, tlirough the lanip (566, the upper right and lower lett contacts o' cani 667 to ground at the armature and baclr contact of relay 63e, thereby indicating to the testman either a short circuit, an open circuit, or L(ground on the lip conductor oi the final selector. Relay Gl which was included in the circuit just traced and operated there'over, locks through its right Winding,` and right arnrature and iront contact to `roundI alt the up per lett contactot canil G69 and its lett armature and liront contact closes an obvious circ-uit for relay 644;. Relay Gli-3 also closes at its right armature and front corrtac-t a circuit for lanip 670 Which extends to ground at the upper left contact of cani 669 (p1 to 1G). It the linal circuit was found to he open, relay 643 would not have operated and lanip G70 Would not, therefore, be ligl'ited. lWith both lamps 666y and 670 lighted the test-nian is apprised of the fact that the trouble at the selector circuit is either due to a snort circuit or ground on the tip conductor.

The test-man now operates the answering key ANS which locks in its operated position and establishes va circuit for reversing relay 645 which may be traced from battery through the winding of relay 645, contact of key ANS to ground at the lett armature and contact oit relay 644. Relay 645 now reverses the connection of ground and battery through the lett winding of relay 643 and the windings ot relays 634 and 663, over the talking conductors of the office and final selector circuits and introduces a resistance 671 ot two thousand ohms. Polarized relay 663 again operates in series with relays 634 and 643 and opens the circuit of supervisory lamp 662 and closes a circuit for relay 638. The circuit of relay 638 may be traced from battery, outer right armature and `front contact of relay 644, winding of relay 638, armature and front contact of polarized relay 663, armature and back contact ot relay 635 to ground at the lower right Contact of cam 616 (15 to 17). Relay 638, upon operating, closes a circuit for the answering relay 646 from battery, winding of relay 646, armature and contact of relay 638 to ground at the lower right contact of cam 669 (16), relay 646 locking to ground at cam 669 through its inner left armature and front Contact. If the linal selector should be grounded on the ring side of its circuit, the polarized relay 663 will not operate as above described upon the operation of the answering key ANS when battery and ground connections are reversed by the operation of relay 645 and under this condition supervisory lamp 662 remains lighted indicating that the ring side ot the nal selector is grounded.

The test-man now operates the start key 607 which closes a circuit for the start relay 608 as follows: battery, relay 608, innermost right. spring and normal contact ol key 612, inner right armature. and back contact of relay 613, conductor 614, key 607, inner right armature and fro-nt Contact of relay 646 to ground. Relay 608, upon energizing, locks iu series with relay 617 to ground at the upper right contact ot' cam 616 (16), and as soon as hey 607 is released` relay 617 energizes, closing the previously traced circuit for advancing sequence switch 610 out ot position 16 into position 17. As the sequence switch leaves position 16, relays 608. 617, 638, 643, 644, 645 and 646 release and the lamp 670 is extinguished. The release ot relay 645 again reverses the hati tery and ground connections to the tip and ring conductors of the final selector circuit thereby causing the release of polarized relay 663, which upon releasing, again lights the lamp 662. Lamp 662 now serves as a disconnect signal.

With the sequence switch 610 of the testing device in position 17 and the lamp 662 lighted, the test-man operates the disconnect key 672 closing a circuit for relay 641 from battery, winding ot relay 641, the contacts or key 672 to ground at the upper right contact of' cam 609 to 18). Relay 641, upon energizing, locks over its right armalture and front Contact to ground at earn 609 and at its inner left armature and front Contact closes a circuit from battery, magnet winding of sequence switch 610, upper left contact of cam 618 (2 to 18), inner letthand armature of relay 641 to ground at the upper right contact of cam 609 for advancing sequence switch 610 into its normal position 1. lVith sequence switch 610 in position 1, all operated relays ot the test device are released and all lighted lamps are extinguished. The testing circuit is now in normal position.

As soon as sequence switch 610 of the 'testing device leaves position 18, ground is removed Jfrom sleeve conductor 241 at the upper right contact oi" cam 609 (1%- to 18) and the holding circuit of control relay 200 ot the oiiice selector 250 is opened, whereupon relay 200 releases. A. circuit is now established for sequence switch 210 extending from battery ythrough the magnet winding ot' this sequence switch, the lower right contact of cam 207, to ground at the lett armature and baclr contact of relay 200 tor advancing 1the sequence switch out ot position 8 into position 18. lilith sequence switch 210 in )osition 18 the circuit of the down-drive magnet 212 is established trom battery. 'through the winding ot magnet 212 to ground through the lower contacts of cam 209 (18), and through the energizat'ion ot this magnet, the switch shaft 214 is pressed against the downdrive drum 237 and moved into normal position. Upon reaching its normal position, shaft wiper 219 engages the normal commutator segment 220, whereupon a circuit is established over the upper right contact et cani 207 to 18) and through the magnet winding of sequence switch 210 for adfancing the sequence switch into normal position.

As soon as sequence switch 210 leaves position 8l, the holdiiig circuit of control relay 300 oit the tinal selector 350 is opened at the right contact et cam 206 and relay 300 releases, closing a circuit from ground at its right armature and baci; Contact, over the upper lett contact of cam to battery through the magnet winding ot sequence switch 310 for driving the sequence switch into position 18. lilith sequence switch 310 in position 18, a circuit is established for the downdrive magnet extending from battery through magnet 335. to ground at the lower contacts of' cam 315. '.lherenergiza- `tion of magnet 335 presses the depending 'lower contacts of cam 673 (15).

portion of switch shaft against ythe downdrive drum 363 thereby moving the switch shaft downwardly into its normal position. Upon reaching its normal position Shaft wiper 347 engages normal segment 351, whereupon a circuit is established .over the lower right contact of cam 312 (1S) to battery through the winding of sequence switch magnet 310 Yto; driving; the sequence switch 310 into its normal position. The circuits ot `the office selector 250 and the final selector 350 are now in their normal positions.

Malte-busy test of' #nel selec/:012

Il it is desired to test the final select-or switch for accuracy in responding to a lousy condition on a final multi ile, the test above described is conducted as before but with the maire-busy key o1" the testing device operated. When, therefore, sequence switch 610 of the testing device reaches position 15 and sequence switch 310 et the final selector reaches the testing position 11, the circuit previously traced from battery at the lower leit contact of cani 309 and 'trom `cround at the upper ycontacts of cam 317 o't' the iinal circuit is established :tor relays G34 and yG08 ot the testinga device. Relay 534., upon on erating, closes a circuit ttor relay 630 which locks to ground at the lower right contactv of cam 616 (15 to 17) as liueviously described. Relay 639 also closes a. circuit tor advancing sequence switch 010 trom position 15 into position 16 as follows: battery, magnet winding of sequence switch G10, lower right contact ot cani 058 (15), lelt. armature and lront contact ot rela-y 639, conductor 077, outer right spring and alternate contact of the maite-lousy key .to `cjround at the ds the sequence switch 610 advances out o't position 15 into position 113, relays 6311 and 663 release allowingv lamp 662 to light. p

At the tinal selector when the test brush 340 engages the test terminal 343 ot the `test line, a reduced potential is encountered since at this time the make-busy key is op erated and the test circuit now extends as previously traced through the windings oit test relay 302 to test brush 8110, test terminal 3413, thence over sleeve conductor 3116 of the test line, sleeve contact of jack sleeve strand of cord 242, sleeve Contact ot kkjack 243, innermost left springv and alternate contact of the make-busy kel/f', outer lett spring and alternate contact of said key, 50 ohm resistance 689 to battery and Vthrough the inner left spring and alternate incense said cam (11 to13)7 contact and armature of relay 301, bach contact and right arma ture of relay 302 to ground, advancing sequence switch 310 out of position 11 into position 13. `When sequence switch 310 reaches position 12, a circuit is closed 'from battery through the right winding of relay 301, lower left contact ot cam S17 (12 to 13), upper right contact ot' cam 317 (1 to 15) to ground. lilith relay 302 deenergized a circuit is now closed from battery at the left armature and back Contact ot relay 802, lett winding` of relay tact ot cam 329 (12 to '13), brush Z310 thence as previously traced to ground at the normal. contact of key P. B. X. Sufficient current now Hows through the left winding of relay 301, aiding the current flowing1 in its right winding to cause the venergi-Zation of this relay. .Relay 301 now attracts its armature and opens the circuit of relay 300 causing this latter relay to deenergize. yllhe release ot ,relay 300 now completes a circuit from battery, through lthe winding of sequence switch magnet 310, upper lett contact oit cam 312 (13), back contact land ri ght armature of relay 300 to ground, moving` sequence switch 310 out of position 13 into position 1%1. ln this position relay 300 is kcncrgimd over a circuit previously traced and cause-. 5 the advance of sequence switch 310 into position 15, relay 300 locking over cmuluctor 2541.- to ground at the right contact of earn 206 ot the otiice selector. In position 15 ot sequence switch 310 a circuit is ,established 'from battery, through the winding` ot the downdrive magnet 335, upper lett and lower right contacts oE `cam 3141- (15), back contact and right armature ot relay 302 to ground. Magnet 335, upon energizing, presses the dependinar portion ot the switch shaftt 837 against the downdrive drum 363 moving' the switch sha-tt 337 dmvnwardly into its normal position. Yllhen the switch shaft reaches normal, the shaft wiper 341:7 enna-gres the normal posi`- tion segment closing' a circuit .over the lower right Contact of cani 312 (8 to 16), through the magnet winding` ot sequence switch 310 tor advancing this sequence switch into position 17.

lmn'iediately 'following the movement of sequence switch 310 inte position 17 the coniinon circuit inchuline,r sequence switch 320 is rendered e'li'ective to produce successive reversals oi current over the talkingcircuit to produce intermittent operation of the polarized supervisory relay G63 of the testing device. A. circuit is `first established from battery, right winding of relay 303, lower left contact of cani 328 (17 to 3), assuming that switch 32.0 is in its normal position, conductor 355, upper riiiht contact of cam (162V to 17), lower left contact of cam 305 (16 to 17), conductor 232, thence as pre- 301, upper con-

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