US2143589A

US2143589A - Telephone system

Info

Publication number: US2143589A
Application number: US141721A
Authority: US
Inventors: Wicks John
Original assignee: Associated Electric Laboratories Inc
Current assignee: Associated Electric Laboratories Inc
Priority date: 1937-05-10
Filing date: 1937-05-10
Publication date: 1939-01-10
Anticipated expiration: 1956-01-10

Description

Jan. 10, 1939. J. WICKS TELEPHONE SYSTEM 3 Shee'ts-Sheet 1 Filed May 10, 1937 4 an 1' 2 nfiwy M H E avg IN VENTOR.

JOHN WICKS BY omwmww ATTORNEYS Jan. 10, 1939. J. WICKS TELEPHONE SYSTEM 3 Sheets-Sheet 2 Filed May 10, 1957 M wE mus

mNG Q5 am v INVENTOR. JOHN WICKS BY 0m, M;

ATTORNEYS.

Jan. 10, l939. J. WICKS TELEPHONE SYSTEM Filed'May 10, 1937 3 Sheets-Sheet 3 INVENTOR. JOHN WICKS BY M #M ATTORNEYS.

Patented Jan. 10, 1939 UNITED STATES PATENT OFFICE TELEPHONE SYSTEM poration of Delaware Application May 10, 1937, Serial No. 141,721 35 Claims. (Cl- 179-25) The present invention relates to signalling systems and more particularly to automatic switches for use in setting up connections between the various lines of an automatic telephone system.

It is well known that the method by which a connection is established from one line of an automatic telephone system to any desired idle second line in the system consists of routing a connection by way of trafilc concentration switches and two or more tandem connected, impulse responsive, numerical switches which operate automatically to select the desired line and to establish a connection thereto. Various types of numerical switches for performing the functions noted are known to the art. With respect to the switching operations per se, i. e., the making and breaking of contacts during the setting up of the desired connections, the present known automatic switches fall broadly into two classes. In switches of the first class, typical of which is the well-known Strowger switch, switch wipers, afiixed to a movable carriage member and arranged selectively to engage oppositely disposed bank contacts, are included directly in the conversational circuits of connections utilizing such switches. In switches of the second class, on the other hand, oppositely disposed pairs of contacts are carried by pairs of contact springs, and actuating members mounted on a carriage independent of the springs are utilized for moving the springs to bring the contacts carried thereby into engagement. As examples of the latter form of switch there may be cited the well-known plunger type Keith line switch and various modifications of the so-called cross bar numerical switch. Switches of the secondmentioned class possess a distinct operating advantage over switches of the first-mentioned class in that the various contact pairs, when in engagement, are not susceptible of becoming momentarily disengaged due to mechanical vibrations transmitted through the switch mechanism to the actuating member associated therewith. As a result, undesired microphonic distortion in the conversational circuits is considerably reduced by the use of switches falling in the second-mentioned class. The minimizing of such distortion is particularly desirable inthose telephone systems wherein radio programs of high fidelity are to be transmitted by wire through the system and between the various transmitting stations of a broadcasting network. Although the known forms of switches falling in the second-mentioned class are reasonably satisfactory in operation, they leave something to be desired with respect to the simplicity oi the apparatus involved and the construction cost thereof.

It is an object of the present invention, therefore, to provide for use in a signalling system an automatic switch which is'of simple, economical and rugged construction, is faithful in operation, and is not substantially affected by mechanical vibrations transmitted thereto.

In general, the object as set forth above is attained in accordance with the present invention by providing an automatic switch wherein the contacts included in the levels of bank contact sets are carried by contact springs under the control of an actuating member movable in three directions with respect to the contacts and carried by a carriage movable in one of the three directions over the bank of contact sets. Each contact set includes two pairs of normally open line contacts and a pair of test contacts. Supported on the carriage and individually associated with each of the contact set levels are line contact closing members and test wipers each of which elements is normally biased to a normal position away from the contacts of its associated level and is operable to an off-normal position to engage the contact springs included in the contact spring sets of the associated level. Means are provided whereby the wipers and contact closing members are selectively actuatable to their respective ofi-normal positions in response to the movement of the aforementioned actuating member in one or more of its three directions of movement. More specifically, two sets of projections spaced along and extending from the actuating member are provided for selectively actuating, during movement of the actuating member, the test wipers and the contact closing members to their respective off-normal positions.

Operating in conjunction with this actuating member are means comprising a vertical step- 40 ping magnet, a horizontal stepping magnet, ratchet and pawl mechanisms individually associated with these magnets, and control means whereby these elements automatically translate the actuating member to a position for conditionlng the test wiper associated with a particu-- lar level of contact sets to test the condition of a particular line terminated at one of the sets included in the associated level, and to actuate the contact closing member corresponding thereto into engagement with the line contact springs associated with the particular line. As pointed out in greater detail hereinafter, the arrangement of the control means depends upon whether t e switch is to be used in an intermediate or 5 final selecting capacity. In the first instance, impulse responsive means are included in the control means for causing the actuating member to be translated step-by-step in one direction in accordance with a series of received impulses to a position for operating a predeter mined one of the test wipers to its off-normal position, following which the carriage upon which this wiper is mounted is automatically moved step-by-step in a second direction, so that the operated test wiper successively engages the test contacts of its associated contact level, until a contact set terminating the line outgoing to an idle succeeding selector switch is found. When this occurs, the actuating member is moved in another or third direction to establish a connection between the line incoming to the switch being operated and the line outgoing to the succeeding selector switch. If, on the other hand, the switch is to be used in a final selecting capacity or as an instrumentality for selecting a particular called line in a particular group of lines, the step-by-step movement of the carriage in the second direction as well as the step-bystep movement of the actuating member in the first direction is carried out in response to the operation of the impulse responsive means included in the switch.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the specification taken in connection with the accompanying drawings, in which Figures 1 and 2 illustrate the structural features of an automatic switch constructed and arranged in accordance with the present invention, and Figs. 3 and 4, considered together, i1-

' lustrate a telephone system including automatic switches of the form shown in Figs. 1 and 2,

used both as intermediate and final selector switches.

Referring now more particularly to Figs. 1 and 2 of the drawings, the improved switching mechanism there shown comprises a bank of contact sets indicated at I0 disposed in the same plane and arranged to form a plurality of levels of contact sets, six of which are shown at H, |2, |3, l4, l5 and I6. Each of these sets includes two pairs of line contact springs respectively having oppositely disposed normally open line contacts thereon and a pair of test contact springs. Thus, the first contact set of the upper level II comprises, as best shown in Fig. 2, a pair of line contact springs l1, l8, a second pair of line contact springs I9, 20, and a pair of test contact springs 2|, 22. The remaining pair of springs is not ordinarily utilized in those automatic telephone systems wherein three-wire trunks are used as links between the various automatic switches embodied therein. Preferably, the oppositely disposed contacts, not shown, of each pair of contact springs are of precious metal, such, for example, as silver or platinum. As pointed out hereinafter, one spring of each pair of springs included in each contact spring set is connected to a conductor embodied in the line outgoing from the switch and the respective other springs of the three spring pairs in each contact spring set are connected to the line incoming to the switch. Thus, considering again the first contact set included in theupper level I l, the springs l8 and 20 may be connected to opposite line conductors of a line outgoing from the switch illustrated, the springs l1 and I9 may be connected to opposite line conductors of a line incoming to the switch, the spring 2| may be connected to the-test conductor ofv the line incoming to the switch, and the spring 22 may be connected to the control or test conductor of the line outgoing from the switch. It will be obvious to those skilled in the art that the line conductors incoming to the switch are multipled to the corresponding springs of each of the contact spring sets. Thus, the springs H, H! and 2| will be connected to the respective corresponding springs, such, for example, as the springs 23, 24 and 25 of the first set included in the second level and to the conductors of the line incoming to the switch. It will further be understood that the outgoing lines terminated at the contact spring sets of each particular level extend to a particular group of succeeding selector switches or to a particular group of subscribers lines, depending upon whether the switch is used in an intermediate or final selecting capacity. By this grouping, as is well known, there may be accomplished the successive selection of a particular group of lines or switches and a particular line or switch in the selected group.

Associated with each level of contact sets is a test wiper and a line contact spring closing member, these elements for the levels II to It, nclusive, being indicated, respectively, at 26 to 3|, inclusive, and 32 to 31, inclusive. Each of the elements 26 to 31 is carried by a carriage 38, which in turn is slidably mounted on a pair of

cross bars

39 and 40 by means comprising brackets 4| and 42. The carriage 38 comprises a base member 4| having outwardly extending ends 42' and 43 between which is resiliently supported, by means comprising

flexible spring strips

44 and 45, a member 46. Each of the contact closing members 32 to 31, inclusive, extends through a hole drilled in the base member 4| and is spring biased to a normal position away from the contact spring sets of the associated level. Thus, the member 32 associated with the level of contact sets extends through an opening in the base member 4| opposite this level of contact sets and is normally biased to the left away from the contact springs l1 and 2| by a spring 41. This contact closing member, like each of the other similar members, is guided in its movement by a bracket 48 aflixed to the base member 4| and having a hole drilled in the right extremity thereof through which the member 32 extends. The normal position of this member is determined by a flange 49 provided thereon which, in cooperation with the extreme right surface of the bracket'48, acts as a stop member against the bias provided by the spring 41. Each of the contact closing members is provided with an insulating member at the right end thereof which insulating member is adapted to engage the oppositely disposed bank contact springs. Thus, the member 32 is provided with an insulating member 50 and each of the remaining members is provided with a similar insulating mem her as shown. The means individually associated with each of the test wipers for actuating insulated from the rocker arm upon which it is supported and is gravitybiased to its normal position away from the test contacts of the contact sets comprising the associated level. Each rocker arm is provided with an upwardly extending finger utilized in the actuating of the wiper carried by the arm to its ofi-normal position. These fingers for the rocker arms 5| and 53 are indicated at 5| and 58'.

In order to actuate each of the wipers 26 to 8|, inclusive, from its normal position to its ofl-normal position, there is provided an actuating member 55 which is slidably positioned by

means comprising brackets

55 and 51 on the member 48 of the carriage 38. This actuating member normally occupies the position shown in the drawings and is movable in a vertical direction by means described hereinafter to any one of a number of oiT-normal positions each of which corresponds to one of the levels of bank contact sets. Spaced along and extending outwardly from this actuating member are projections, two of which are indicated at 58 and 59, for successively engaging, during vertical movement of the actuating member, the above noted fingers extending upwardly from the respective test wiper supporting rocker arms. Extending inwardly through a slot 88 provided in the member 48 are additional projections, two of which are indicated at BI and 62, which are individually associated with the line contact spring closing members individually corresponding to the contact set levels.

In order to operate the actuating member from the normal position shown in the drawings to any one of its off-normal positions, there is provided means for stepping this member vertically downward. This means comprises a vertical magnet 53 having associated therewith a spring biased armature 84 pivoted at 84' and-carrying a pawl 85 for engaging the teeth of a ratchet member 81. This last-mentioned member is supported on the frame, not shown, of the switch in any suitable manner, such, for example, as by the

brackets

88 and 89, is biased by a spring 18 to its uppermost or normal position, and includes a cross arm 1| extending parallel with the levels of bank contact sets and between the

sides

12 and 13 of a U-shaped member 14 mounted on the actuating member 55. A holding pawl 15 pivotally mounted at 18 is provided, which pawl is gravitybiased to engage the teeth of the ratchet member 81 but, in the normal or home position thereof is held away from these teeth by an arm 11 mounted on the base member 4|. may be provided, which are adapted to be engaged by the upper end of the ratchet member 61 to hold the springs in their off-normal posi tions when the ratchet member is operated to its uppermost or home position by the spring 10.

In order to move the carriage 38 to the left so that all of the test wipers and all of the line contact closing members are moved along their respective associated contact set levels and the actuating member 55 is moved therewith, there is provided a coil spring 19, having one end connected to this carriage and the other end, not shown, affixed to a point on the frame upon which the switching mechanism is mounted. This movement is accomplished in a step-by-step manner by the provision of an escapement mechanism, indicated generally at 80,-comprising a drum mounted for rotation on a shaft 8| and having a flexible cord 8| wound therearound,

Off-normal springs indicated at 18 one end of which is secured to the drum and the other end of which is secured as indicated at 82 to the carriage 38. Rotation of the drum is under the control of an escapement wheel 83 fixedly mounted on the drum and having associated therewith a spring biased escapement pawl 84 adapted to be pivotally mounted as at 85 on the frame, not shown, supporting the escapement mechanism, and a driving pawl 86 pivotally mounted at 81.

Magnets

88 and 89, associated respectively with the

pawls

84 and 85, control the operation of the escapement mechanism. The operation of this escapement mechanism is well known in the art and a detailed description thereof is accordingly omitted. Off-normal springs indicated at 98 may be provided which normally occupy the off-normal position shown in the drawings when the switch is idle and the carriage 88 occupies its home or normal posiion.

For the purpose of operating the actuating member 55 inwardly to cause one of the projections GI, 82, etc., to move its associated line contact closing member into engagement with the contact springs of a selected set, there are provided magnets 9| and 92 fixedly mounted on the base member 4| adjacent either end of the member 48 and having pole faces positioned opposite the latter member. It will be understood that the member 46 is constructed of a magnetic material or is provided with magnetic shoes oppositely disposed with respect to the magnet pole faces so that, when the magnets 9| and 92 are energized, it is moved toward oppositely disposed pole faces of the magnets.

In order to facilitate an understanding of the operation of the switch mechanism just described, a brief description of the arrangement of the pro jections 58, 59, etc., and 6|, 82, etc., is deemed to be in order. The spacing of the

projections

58, 59, etc., and the projections SI, 62, etc., along the actuating member 55 is such that, for any predetermined off-normal position of the actuating member 55, only one oi the test wipers is moved to its off-normal position and only the line contact closing member associated with the operated test wiper is conditioned to be actuated into engagement with the line contacts of the associated level. Thus, when the member 55 is moved from the normal position shown in the drawings to its first off-normal position, the projection 58 rides under the finger 5| of the rocker arm 5| and this arm is rocked in a counterclockwise direction to bring the wiper 28 to a position wherein it is engageable with the lower test contacts, such, for example, as the contact 22, of the associated level of contact sets ll. With the member 55 in this position, the projection 59 stands just ready to ride under the finger 53' of the rocker arm 53 upon which is mounted the wiper 21 associated with the next succeeding level of contact sets l2. Thereafter, and if the actuating member 55 is moved from its first oif-normal position to its second off-normal position, the projection 59 rides under the finger 53 to rotate the rocker arm 53 in a counterclockwise direction and thereby actuate the test wiper 21 to a position wherein it is engageable with the test contacts of the level of contact sets 'l2. Simultaneously with this second movement of the member 55, the projection 58 rides out from under the finger 5| to permit the wiper 28 under the force of gravity to move back to its normal position. Succeeding steps of the actuating member 55 result in successive operation of the succeeding test wipers to their respective off-normal positions, each test wiper being returned to its normal position as the succeeding test wiper is actuated to its offnormal position. By this manner of control of the test wipers, the switch is conditioned to test the condition of one or all of the lines in a selected group of lines.

As each test wiper is operated to its off-normal position in-the above manner, the line contact spring closing member associated therewith is conditioned to be actuated into engagement with the springs of the associated contact level.

, For example, when the member 55 is moved to its first oil-normal position, thereby to actuate the wiper 26 to its off-normal position, the projection 6| is moved opposite or into alignment with the left end of the contact spring closing member 32 and, similarly, when the member is moved from its first oiT-normal position to its second off-normal position, the projection 62 becomes aligned with the member 33. Each time a projection is moved opposite its associated member and into alignment therewith, the preceding projection is moved out of alignment with its associated member and, consequently, only one line contact spring closing member is conditioned foractuation into engagement with the contact spring of its respective associated contact set level for any one oil-normal position of the actuating member 55.

In the operation of the switch mechanism thus far described and as will be pointed out in greater detail hereinafter, with the switching mechanism in the normal position shown the means comprising the vertical stepping magnet 63 and the ratchet member 61 for moving the actuating member 55 vertically downward is inoperative, with the last mentioned member in its home position since the'holding pawl 15 is held by the arm 11 away from the teeth of the ratchet member 61.

Immediately following the seizure of the switch, however, the magnet 88 is momentarily energized to rotate the pawl 84 in a clockwise direction and thereby permit the spring 19 to pull the carriage 38 one step to the left. When this occurs, the arm 11 mounted on the carriage 38 is moved from engagement with the holding pawl 15 so that this pawl, under the force of gravity, moves into engagement with the teeth of the ratchet member 81. During the first series of impulses transmitted to the switch, the

magnet 53 is alternately energized and de-energized to move the ratchet member 61 and, as a consequence, the actuating member 55 step-bystep in a downward direction until the actuating member occupies one of its off-normal positions corresponding to the impulses of the re ceived series of impulses. In this position, the test wiper corresponding to this off-normal position of the actuating member stands in its offnormal position ready to engage the test contacts of its associated level of contact sets and the corresponding projection for actuating the contact closing member associated with this contact set level is aligned with the last-mentioned member.

In the event the mechanism is used in an intermediate selecting capacity, the magnet 88 included in the escapement 88 is, following the step-by-step vertical movement of the actuating member 55, automatically energized and deenergized to permit the carriage member 38 to be moyed horizontally to the left by the spring 18 so'that the operated test wiper engages the test contacts of its associated level of contact sets. When a particular line corresponding to an idle succeeding selector switch in the selected group is encountered, this operated test wiper completes a circuit for energizing a relay which causes the permanent de-energization of the magnet 88 and the energization of the magnets 9| and 92. As a consequence, the actuating member 55 is moved inwardly so that the projection standing opposite the contact closing member associated with the operated test wiper engages this member and moves it into engagement with the contact springs at which the particular selected line terminates. The switching mechanism is thereupon automatically locked in its operated position until the switch is released for further use. When so released, the magnet 89 is alternately energized and de-energized and, in cooperation with its driving pawl 86, drives the escapement wheel 83 secured to the drum 88' of the escapement mechanism 88 against the bias offered by the spring 19, to move the carriage 38 back to its home or normal position. Upon this position being reached, the arm 11 mounted on the carriage 38 engages the holding pawl 15 to release the ratchet member 61 and permit the spring 18 to return this member and the actuating member 55 to their respective normal or home positions.

In the event the switching mechanism is used as a connector switch or an instrumentality for selecting a particular called line in a selected group of lines the operation differs from that described above only in that the magnet 88 is energized in accordance with a second series of impulses transmitted to the mechanism. Thus, the carriage 38 is moved step-by-step to the left in accordance with the impulses of the second digit until the operated test wiper associated with a selected level of contact sets stands in engagement with the test contact of a contact set terminating a particular called line. The release of the switch is accomplished in the exact manner described above. I

Referring now more particularly to Figs. 3 and 4 of the drawings, there is illustrated a telephone system wherein automatic switches of the form justdescribed are used as the impulse responsive, intermediate and final selecting switches. In general, the system comprises a plurality of telephones or subscribers substations, two of which are shown at A and 13, adapted to be interconnected by means including their respective associated subscribers lines I88 and I 45 and switch trains including the aforementioned intermediate and final selector switches. These switch trains, when established, may individually comprise the usual line switch associated with each subscrlbers line, an intermediate selector switch accessible to the line switch associated with the calling subscribers line, and a final selector or connector switch accessible to the operated intermediate selector switch and having bank contacts in which the called subscriber's line terminates. Thus, in the system shown, the line I88 terminates at a line switch SW3, which switch has access to a group of intermediate selector switches, one of which is shown at SIM. These intermediate selector switches in turn have access to groups of final selector or connector switches, each connector switch of each group having its bank contacts multiplied to the bank contacts of the other switches in the same group and connected to serve a corresponding group of subscribers lines in the system. Thus, the u selector switch SIM has access to a number of connector switches, one of which is shown at SI40, in the bank contacts of which a group of subscribers lines, including the line I45, terminate. It is well known that by this arrangement any subscriber may by proper manipulation of the impulsing device at his substation establish a connection between his line and any other idle subscriber's line in the system.

Each of the line switches included in the system, such, for example, as the line switch SI03, may be of any desired commercial construction although preferably is of the well-known rotary type having three levels of bank contacts, wipers corresponding to the three levels, a ratchet and pawl mechanism for driving the wipers, an operating magnet for actuating the ratchet and pawl mechanism, and control means whereby the operating magnet is energized to operate buzzer fashion when a call is initiated on the line assooiated with the corresponding line switch and is deenergized when the wipers are rotated into engagement with a set of contacts corresponding to the first idle intermediate selector switch available.

Neglecting for the present the details of the intermediate and final selector switches SIM and SI 40 and the control means respectively included therein, the system as briefly described above is entirely conventional in form and its operation is well understood in the art. In brief, when a subscriber, such, for example as the subscriber at the telephone A, initiates a call over the line I00 to a second subscriber's line, such, for example, as the telephone B, by lifting his receiver from its hook, the line switch SI03 associated with the calling subscriber's line operates to select an idle intermediate selector switch and to condition the same to be responsive to impulses transmitted from the impulsing device at the telephone A. As noted above, each of the intermediate selector switches has access to one or more final selector switches at which any subscribers line in the system terminates. Thus, if the intermediate selector switch SIM is seized by the line switch SI03, it operates in the specific manner described hereinafter in response tothe dialing of the first digit at the substation A to select a group of trunk lines extending to the final selector switches at which the called line I45 terminates. Following this, the seized intermediate selector switch SIM automatically selects a trunk line leading to an idle final selector switch in the selected group of switches and connects the calling subscriber's line I00 through to seize the idle final selector switch. Thereafter, and in response to the dialing of the second digit, the seized final selector switch selects the group of lines in which the called subscriber's line is included. With the switch train in this condition, and when the final or third digit is dialed, the seized final selector switch selects the particular called line in the selected group of lines and establishes a connection between the calling and called lines when the called telephone B is answered.

' The system conventionally includes means whereby ringing current and ring-back tone current are automatically transmitted, respectively, to the substations of the called and calling parties in case the called line is idlev and upon the final selector switch seizing the called line. Also, in accordance with conventional practice, means are provided whereby, in the event the called line is found busy, the calling line is not connected thereto and busy tone current is transmitted arrangement is such that the switch train utilized in establishing the connection is released only when the connection is cleared out at the calling partys substation, the entire switch train being held operated when the called party is the first to han upi Each of the intermediate and final selector switches embodied in the system preferably has incorporated therein the features of the improved automatic switch illustrated in Figs. 1 and 2, although it is noted that the system may only partially comprise switches of this form, the remaining automatic switches being of any wellknown step-by-step type, wherein impulse responsive means are utilized to control the operation. The switches SIM and SI I0 are, however, of the exact form illustrated in Figs. 1 and 2. The switch SIM has access over one hundred outgoing trunk lines, one of which is shown at I I2, to each of one hundred final selector switches and, similarly, each of the final selector switches has access to one hundred subscribers lines terminating in the bank contacts thereof. In the switch SIM, the conductors CI I3, CI I4, and CI I5, comprising the trunk line II2 outgoing to the final selector switch SI40, terminate, respectively, at the bank contacts SCI l6, SCI I1, and SCIZI, included in one set of bank contacts of the switching mechanism SI I I. The conductors of the line incoming to the switch and comprising the conductors CI08 to CI I0, inclusive, terminate at the respective bank contacts SCI20, SCI I8, and SCI I9, which last-mentioned complete the contact set shown. The respective pairs of contact springs upon which the normally open contact pairs SCIIB, SCII8; SCII'I, SCII9 and SCI2I, SCI20 are carried are adapted to be moved into their contact closed positions by a contact closing member diagrammatically illustrated at I90. This contact closing member is arranged to be actuated by an actuating member, not shown, corresponding to the member 55 shown in Figs. 1 and 2, when this actuating member occupies a predetermined one of its off-normal positions and is itself actuated in response to the energization of a pair of magnets, one of which is shown at M210, corresponding to the magnets 9| and 92 shown in Fig. 2. The vertical step-by-step movement of the actuating member to condition the contact closing member I90 to engage the contact springs of the set shown is accomplished through the alternate energization and deenergization of a vertical magnet M250, and the horizontal step-by-step movement of the carriage upon which the actuating member is mounted is similarly accomplished through the alternate energization and de-energization of a horizontal magnet M280. Associated with the level of contact sets including the set shown is a test wiper SWI2I', which, as will be understood, is mounted on the carriage member carrying the contact closing member I90. Retention of the switch mechanism SI II in any operated positionis attained by the provision of the release magnet M290. In order selectively to energize the enumerated magnets to cause the switch SI I I to perform the selecting functions briefly described above, there are provided control means comprising the line relay R2I0, the hold relay R220, the series relay R230, the interrupter relay R240, the

polarized switching relay R200, off-normal springs ONSI36 and ONSISI, the circuits conwhich the control thereof is achieved.

The final selector or connector switch SI40, like the intermediate selector switch SI04 has embodied therein a switching mechanism SI 44 of the form illustrated in Figs. 1 and 2. In this switch the contacts SCI5I, SCI52 and SCI 53 included in one contact set of the bank contacts embodied in the switch are connected respectively to the conductors CI43, CI42 and CI80. The conductors CI46, CI and CI48 of the called subscribers line I45 terminate at the contacts SCI50, SCI49 and SCI54, also included in this contact spring set. The test wiper associated with the level of contact spring sets including the set noted is indicated at SWI55 and the contact spring closing member associated with this level is indicated at I9I. It will be understood that the two lastnamed elements are under the control of an actuating member, corresponding to the member 55 illustrated in Figs. 1 and 2. The vertical step-bystep movement of this member to a predetermined position for causing the wiper SWI55 to be operated to its off-normal position wherein it is engageable with the test contacts of its associated level is under the control of a vertical magnet M315. The horizontal step-by-step movement of the carriage upon which the actuating member is mounted is under the control of a horizontal magnet M380, and the movement of the actuating member in the third direction to cause the operation of the contact closing member I9I to its ofinormal position such that it closes the contacts SCI5I, SCI49; SCI52, SCI50 and SCI53, SCI54, is under the control of two magnets, one of which is shown at M385, corresponding to the magnets 8| and 92 shown in Fig. 1. The release magnet for this mechanism is indicated at M330. In order to control the energization of the magnets noted, thereby to cause the switch SI40 to perform the line group and line unit selecting functions briefly described above, there is provided therein control means comprising the relays R300, R3I0, R320, R330, R340, R350, R360, R310, off-normal springs ONSI5'I and ONSI56, their control and controlled circuits. The switch SI40 also has associated therewith ringing apparatus, not shown; for transmitting ringing current to a called subscribers line and ring-back tone current to a calling subscribers line, and a generator, not shown, for transmitting busy tone current to a calling subscribers line in the event a particular called line is found busy.

Considering now the detailed operation of the intermediate selector switch SI04 during the above-described sequence of operations, when this switch is seized by the line switch SI03, a circuit is completed for energizing the line relay R2I0, which circuit extends from ground at the lower winding of the relay by way of the elements C I 21, RC205, RA204, CIOI, SI03, CI02, through the bridge across the line conductors CIOI and CI02 at the calling subscribers substation A and through the elements CIOI, SI03, CI05, RA20I, RC202, CI28 and the upper winding of the relay R2I0 to battery. The line relay R2I0 operates due to its energization over the above-traced circuit to complete, at its armature RA2I I, an obvious circuit extending from ground at the armature RA20'I for energizing the slow-to-release hold relay R220. Simultaneously, the line relay R2I0 completes, at its armature M2, a circuit for momentarily energizing the magnet M280, this circuit extending from ground at the arm'ature noted by way of the elements RA22I, CI33, and

v 2,148,586 trolled by these elements and the circuits by the winding of M280 to battery. This momentary energization of M280 causes the escapementmechanism associated with the carriage, upon' which the test wiper SWI 2 I and the contact closing member I90 are mounted, to take one step such that the oiT-normal springs ONSI3I, corresponding to springs 90 of the mechanism shown in Fig. 1, are closed and the holding pawl of this mechanism, corresponding to the pawl I5 of the mechanism shown in Fig. 1, is operated into engagement with the teeth of its associated ratchet member in the manner previously described above. When the oil-normal springs ONSI3I close, a circuit is completed for energizing the lower winding of R200, this circuit extending from ground on CI08 by way of CI24, CI22, ONSI3l, CI23 and the lower winding of R200 to battery.

Shortly following the energization of the magnet M280, the hold relay R220 operates to interrupt, at RA22'I', the above-traced circuit for M280. At RA221 and RA228, an alternative circuit is prepared for energizing M280. The hold relay R220, upon operating, applies, at RA22I, ground to C|08, thereby to hold.,the preceding operated line switch SI03 in its operated condition. At RA222 and R0223, the hold relay R220 prepares an obvious circuit for energizing the series relay R230, which circuit is held open at RAZII of R2I0. At RA225, the relay R220 prepares a circuit, traced hereinafter, for energizing the interrupting relay R240. At RA226, the relay R220 completes a multiple circuit for energizing the lower winding of the polarized relay R200, this circuit extending from ground on CI08 by way of the elements CI24, CI22, RAZZB, CI23, and the lower winding of R200 to battery. This polarized relay is so constructed that'it does not operate in response to the energization of its lower winding but is conditioned by such energization to be exceedingly fast acting when its upper Winding is subsequently energized. With the relays R2I0 and R220 of the switch SI04 operated and the carriage upon which the wiper SWI2I' and the contact closing member I90 are mounted stepped to its first oil-normal position, the control means included in this switch is conditioned to be responsive to the series of impulses comprising the first digit dialed at the calling substation A.

At the beginning of the first impulse of this digit, when the previously traced circuit for energizing R2I0 is interrupted at the impulsing device of the calling substation, this relay restores to complete, at RA2I I and RC2 I 3, a circuit for energizing M250 and R230 in series, this circuit extending from ground at RA2 01 by way of the elements R0209, RA2I I, RC2I3, RA222, RC223, the winding of the relay R230, CI30, and the winding of the vertical magnet M250 to battery. The relay R230 operates, in response to its energization as above described, to open, at RA23I, a point in the circuit for energizing the upper winding of R200 and to open, at RA232, a point in the circuit, traced hereinafter, for energizing R240. The vertical magnet M250 also operates its armature and, from a consideration of the mechanism shown in Fig. 1, it will be seen that this magnet, which corresponds to the magnet 63 of the figure noted, operates its associated actuating member, corresponding to the member 55 of the figure noted, to its first ofi-normal position. Upon taking this first step, the off-normal springs ONSI36 are closed, but without effect at this time.

At the end of the first pulse of the first digit, when R2I0 again operates, the previously traced circuit for energizing the vertical magnet M250 on the other hand, this switch is busy,

. 2,148,589 is interrupted at RA2II, thereby conditioning v M250 and its associated ratchet and pawl mechanism to step the actuating member for the wiper SWI2I' and the contact closing member l00 to its second oil-normal position. During each succeeding impulse of the series of impulses comprising the first digit, R2I0alternately operates and restores to cause M250 to step the associated actuating member at the rate of one step for each impulse received by the switch. During such impulsing, the relays R220 and R230, by

virtue of their slow-to-release characteristics, re-

main operated. I In view of the preceding description of the mechanism shown in Figs. 1 and 2, it will be apparent that, ifthe outgoing line I I2 terminates at a set of bank contacts in the third level, corresponding to the third off-normal position of the actuating member noted, the first digit dialed at the calling substation will necessarily comprise three impulses so that, at the conclusion of this digit, the test wiper SWI2I'. is operated to its off-normal position wherein it is engageable with the row of test contacts in the level including the test contact SCI2I. Also in view of the previous description, it will be understood that the projection on the actuating member associated with the contact closing member I stands opposite and is'in alignment with the last-mentiond member so that, when the two magnets including the magnet M210 are energized, this contact closing member will be driven into engagement with the springs carrying the contacts SCIIO and SCI20. p

Shortly following the conclusion of the first digit, R230 restores to complete the above-noted circuit for energizing R240, this circuit extending from ground at RA201 by way of the elements R0209, RA225, RA232, CI32, ONSI3B, CI3 I RA24I, and the winding of R240 to battery. By virtue of the interrupting contacts associated with RA24 I, R240 operates buzzer fashion, thereby alternately to make and break at RA242, the circuit for energizing the horizontal magnet M280. This magnet M200 is energized over a circuit extending from ground at RA242 by way of the elements CI34,-RA228, RA22'I, CI33 and the winding of M280 to battery. Each time the horizontal magnet M280 is energized over the above-traced circuit, it operates the pawl associated with the escapement mechanism of the switching mechanism SI I I, permitting the spring-biased carriage upon which the test wiper SWI2I' is mounted to be stepped horizontally one step along the contact set levels. Thus, the test wiper SWIZI' is successively brought into engagement with the test contacts of the contact sets of the level including the contact set' shown. Assuming that the trunk 2 leads to the first idle final selector switch in the group of such switches terminated at this level, this stepping operation' will continue until the switch wiper SWI2I' engages the test contact SCI2I.

It will be seen from a consideration of the final selector switch SI40 that, if any particular switch in the selected group is idle, battery is present on the control conductor incoming to the switch and corresponding to the conductor Cl I5 whereas, if it is busy, ground is present on this conductor. Thus, when the switch SI40 isidle, battery from the ofi-normal springs ONSISG is impressed on CH5 by way of CI and RA3I2 of R3). If. RA3II of R3l0 is operated so that ground is impressed on CH5. With the various final selector switches winding of R200,

' SWI2 I to battery on the test contact SCI2 I.

This operation connects the conductors CI I0 to the outgoing conductors CI I5, CI I3 and or the selected group thus marked in the level of bank contacts including the test contact SCI2 I, the switch mechanism sl II continues to operate until SWI2I engages SCI2I. When this occurs. a circuit is completed for energizing the upper this circuit extending from ground on Cl08 by way of Cl24, the upper winding of R200 and the elements CI20, RA23I, CI23, In response to the energization of its upper winding over the above-traced circuit, R200 immediately operates to interrupt, at .RA20'I, the previously traced circuit for R240, whereby the carriage upon which SWI2I' is mounted is stopped with this wiper in engagement with SCI2I. At its armature RA209', the polarized relay R200 completes an obvious holding circuit for maintaining its lower winding energized independently of R220. It is noted that, when once operated. the lower'winding of R200, if energized, maintains the relay in its operated position.

. At RA20'I, the relay R200, upon operating, completes a circuit extending by way of the elements R0200 and (H25 for energizing the pair of magnets including M2'I0. As noted above, these magnets correspond to the magnets 9| and 92 of the switch mechanism shown in Figs. 1 and 2, and the energization thereof results in the operation of the actuating member associated with the switch contact closing member I30, in its third direction, thereby to cause this contact closin member to be moved into engagement with the springs carrying the contacts SCII8 and SCI20. CI08 to CI I4, respectively, thereby to cause the seizure of the switch SIM.

At RA20I and RA204 and their respective associated contacts R0203 and R0206, the relay R200, upon operating, connects the calling subscribers line through to the seized final selector switch SI40. Atthese same armatures and their respective associated contacts R6202 and RC205,

the previously traced circuit for energizing the line relay R2I0 is interrupted. Upon restoring, the last-mentioned relay opens the operating circuit for R220, which latter relay also restores to prepare, at RA222, an alternative circuit for energizing R240, which circuit is held open at RA20'I. At RA228 and RC229, the hold relay, upon falling back, prepares a circuit for energizing the release magnet M230. At RA22I, the relay R220 removes multiple ground from the control conductor CI03, ground having been applied to this conductor in the seized final selector switch SI40'in the manner described below.

When R200 operates, to extend the calling line to the seized final selector switch SI40, a circuit is completed for energizing the line relay R300, included in this switch, this circuit extending from ground at theupper winding of this relay by way of CI63, the upper side of the loop extending to the calling substation, through the bridge across the line conductors at this substation, back over the'lower side of theloop, CI62, and through the lower winding of R300 to battery. Upon operating, R300, at RA30I and R0302, completes an obvious circuit'for energizing the slowfor energizing the vertical magnet M315 and R360 in series. It will be noted that the ground applied to the control conductor CH5 is extended back by way of $CI2I and SCI20 to CI08, thereby to hold the selector switch.SIO| and the line switch SI03 operated. This application of ground to the control conductor'CI IS occurs before R220 included in the selector switch SIN falls back to remove ground from CI08 at RA22I.

' With the system in this condition, it will be seen that the connection has been extended to the seized final selector switch 8H0 and that only the relay R200 and the pair of magnets including M210 of the switch SI 04 are operated.

The operation of R300 and R3I0 in the seized final selector switch SI 40 conditions this switch to be responsive to impulses comprising the two final digits dialed at the calling substation A. Thus, when R300 operates, and before R3I0 pulls up, a circuit is momentarily completed for energizing the horizontal magnet M380, this circuit extending from ground at RA304 by way of the elements RA3I1, CI13 and M380 to battery. As pointed out previously, this magnet corresponds to the magnet 88, shown in Fig. 1 of the drawings, so that, upon its energization, the carriage, upon which the contact closing member I9I and the test wiper SWISS are mounted, is stepped to its first oil-normal position whereby the arm, corresponding to the arm 11 in the switch mechanism of Fig. 1, is moved from engagement with its associated holding pawl, corresponding to the pawl 15 of this figure. As a result, the ratchet and pawl mechanism associated with the vertical magnet M315, corresponding to the magnet 63, is rendered effective to step the actuating member for the test wiper SWISS and the contact closing member I9I to the desired one of its predetermined oif-normal positions. When R3I0 pulls up, shortly following the energization of M380, the circuit for this magnet is broken at RA3I1, and the carriage is brought to rest in its first oflE-normal position. It is noted that the off-normal springs ONSISS are opened as the carriage is stepped to its first off-normal position.

At the beginning of the first impulse of the second digit, R300 restores to complete, at RA30I, the above-mentioned circuit for energizing the vertical magnet M315 and R360 in series, this circuit extending from ground at RA30I by way of the elements RC303, RA3I4, RC3IS, CI10, ONSCISI, ONSCI60, CH1, R360 and M315 to battery.

The relay R360 operates, in response to its energization overthe above-traced circuit, and completes, at RA362, an alternative. circuit, excluding the oil-normal springs ONSIS1, for energizing M315 and R360 in series. At RA36I the relay R360 interrupts a point in the circuit, traced hereinafter, for energizing R320.

The vertical magnet M315, upon being energized in the above manner, in cooperation with its associated ratchet and pawl mechanism, steps the actuating member associated with the test wiper SWISS and the contact closing member I9I to its first off-normal position. Upon the actuating member taking this first step, the springs ONS I 51 are operated to the off-normal position, whereby a circuit is prepared at ONSCIS8 and ONSCISQ for energizing the interrupter relay R310, and a circuit is prepared at ONSCIGI and ONSCI82 for energizing the slow-to-release relay R320, R230 and the horizontal magnet M380, these circuits being held open at RA36I. At the conclusion of the first pulse, when R300 operates to cause the deenergization of the vertical magnet M315, this magnet in conjunction with its ratchet and pawl mechanism is conditioned to drive the associated actuating member to its respective second of!- normal position. The magnet M315 is alternately energized and de-energized in accordance with the impulses of the second digit to step this actuating member to the off-normal position corresponding to thenumber of impulses .in the series of impulses comprising the second digit dialed. Thus, if it be assumed that the called subscribers line I45 terminates at a contact set in the third level of bank contacts in the switching mechanism SI, the second digit will necessarily comprise three impulses, so that, at the conclusion thereof, SWISS is actuated to its off-normal position and the contact closing member I 9| is conditioned for actuation into engagement with the contact springs of the associated set shown. It will be understood that the relays R3I0 and R360, due to their slow-to-release characteristics, remain operated during such impulsing.

At the conclusion of the second digit, R300 re mains energized for a sufficient period of time to permit R360 to restore. When this occurs, the above-noted alternative operating circuit for R360 and the vertical magnet M315 is interrupted at RA362 and the circuits, traced hereinafter, for R320 and the horizontal magnet M380 are prepared at RA36I. Thus, the final selector switch SI40 is conditioned to be responsive to the impulses comprising the third or units digit dialed at the calling substation A.

At the beginning of the first impulse of the third digit, when R300 again restores, the lastmentioned circuits for energizing R320 and the horizontal magnet M380 are completed, these circuits both starting at the armature RA30I and extending by way of the elements RC303, RA3I4, RC3IS, CHO, ONSCIGI, ONSCI62, CH6, to RA36I, where they divide, one extending by way of CIB I and through R320 to battery and the other extending by way of RA3S4, Cl12, RA332, CI13 and M380 to battery. The relay R320, upon operating, interrupts, at RA32I and R0322, a point in the circuit, traced hereinafter, for energizing the lower winding of R350 and prepares, at RA32I and RA323, a circuit for energizing the busy relay R330. The horizontal magnet M380, upon being energized over the above-traced circuit, operates its armature to permit the associated escapement mechanism, corresponding to that shown in Fig. 1, in cooperation with the carriage biasing spring, corresponding to the spring 19 of the mechanism shown in the figure noted, to step the carriage upon-which the off-normally positioned actuating member is mounted to its second off-normal position or to a position corresponding to the first contact sets of the respective bank contact set levels. Due to the alternate energization and de-energization of the horizontal magnet M380 in accordance with the impulses comprising the third digit, this carriage is stepped horizontally at the rate of one step for each impulse until it stands over the contact set of the level corresponding to the impulses of the digit dialed. In the present case, if it be assumed that the contact set shown is the fourth contact set in the third level, the third digit will necessarily comprise four impulses so that, at the conclusion thereof, the carriage member carrying SWISS and the contact closing member I! stands in its fifth ofi-normal position with SWISS in engagement with SCIS4.

The sequence of operations which follow the actuation of the carriage to this position depends upon whether the called line I 45 is found idle or busy. Thus, at the time SWISS engages SCISl R200 to restore.

' the operating circuit for the pair of magnets ina,14a,sss

at which the control conductor CHO of the called line terminates, the slow-to-release relay R320 is operated so that a circuit is prepared for energizing the busy relay R330. It the called line I is busy, ground is present on the control conductor CHO, whereas, it the called line is idle, battery extending from one of the relays in the line switch associated with this line is present on the control conductor. Hence, if the line I05 gizing the lower winding of R350. At its arma-. ture RA332, the relay R330 interrupts a point in the above-traced circuit for energizing the horizontal magnet M300 and, at its armature RA33I,

,it prepares an alternative circuit for maintaining itself operated when the slow-to-release relay R320 restores. The alternative circuit noted extends irom ground at RA3I3 by way of the elements CI61, RA352, CI10, RA33I, RC324, RA323, R330 to battery. The busy relay upon operating also applies, at RA330, busy tone current to the loop extending through the operated selector switch SIM and the operated line switch SI03 to the receiver at the calling subscriber's substation, to indicate to the calling party thereat the busy condition of the called line.

When this occurs, the calling party may, by hanging up, interrupt the loop holding R300 operated thereby to cause the hold relay R3I0 to restore. This latter relay, upon restoring RA3I I, removes ground from the control conductors CI I5 and CI08. Removal of ground from CI08 permits the line switch SI03 and the polarized relay The last-mentioned relay, upon falling back, completes a circuit for energizing R200, this circuit extending from ground at RA201 by way of the elements R0209, RA2II, RC2I3, RA222, R0224, RA232, CI32, ONSI35, CI3I, RA24I, R240, to battery. Simultaneously with the completion oi the above-traced circuit,

cluding the magnet M210 is interrupted at R0203. These two magnets upon de-energizing permit the actuating member associated with the wiper SWI2I' and the contact closing member I90 to move away from the contact closing member I90. The spring bias exerted on the member I90 moves this member to its normal position thereby to return the contact springs shown in the mechanism SI II to their open circuit positions and to disconnect the conductors Cl08 to CI I0, inclusive, from the trunk conductors CI I 5, CI I3 and CI II, respectively. The interrupter relay R240, by

virtue of the interrupting contacts associated with'RA2lI, operates buzzer fashion alternately to energize and de-energize the release magnet M290 over a circuit extending from ground at RA242 by way of the elements CI3I, RA228, R0229, CI3S and M290 to battery. The magnet M290 which corresponds to the magnet 09 in the mechanism of Fig. 1, in cooperation with its to its normal or home position at which time the oil-normal springs ONSIfl are opened. Thus, the intermediate selector switch Si is restored t'onormal.

restoration of the final selector .or connector switch 8H0, following the restoration ct R300 and R3I0, is quite similar to that described above Ior the intermediate selector switch SIM. When R3I0 restores RA3I3, the abovetraced holding circuit for R330 is interrupted and this latter relay restores. Upon the restoration of RA3I4, a circuit is completed for energizing R310, this circuit extending from ground at RA30I and by way of the elements RC303, RA3I4, RC3I6, CI1I, ONSCIS9, ONSCI53, CI10, RA31I, R310 to battery. The relay R310, by virtue of the self-interrupter contacts associated with RA31I, operates buzzer fashion and, at RA312, alternately completes and interrupts a circuit extending by way or CI1S for energizing the release magnet M390. This magnet also corresponds to the magnet 89 shown in the mechanism of Fig. 1 and, in cooperation with its associated pawl and the ratchet wheel of the escapement mechanism embodied in the switching mechanism SI, moves the carriage upon which the elements I9I and SWISS are mounted to its normal or home position, at which time the oilnormal springs ONSI 56 are closed and the abovetraced circuit for R310 is broken when the of!- normal springs ONSI51 are restored to normal, as explained below. During the return movement of the carriage and as it takes its final step, the arm mounted thereon, corresponding to the arm 11 shown in Fig. 1, actuates aholding pawl, corresponding to the pawl 15 shown in this figure, away from its associated ratchet member, thereby to permit the actuating member for the elements I9I and SWISS to return to its normal or home position, at which time the oil-normal springs ONSI51 are restored to normal. With the system in this condition, the switch train set u in the course of establishing the connection to the called line I 05 is entirely released.

In the event the called line I45 is idle at the time it is tested by the final selector switch SI40, battery from a relay in the line switch associated with this line is present on the control conductor CH8 and, consequently, the busy relay R330 is not energized in the manner set forth above. Shortly following the testing of this line and when R320 restores, a circuit is completed for energizing the lower winding of the series relay R350, this circuit extending from battery on the control conductor CI 48 by way of the elements SCISl, SWISS, CI59, RA32I, RC322, CI69, RA333, C163, the lower winding of R350, CI61 to ground at RA3I3. The relay R350 operates, upon the energization of its lower winding, to complete, at RA3S3, a circuit for energizing its upper winding, which circuit extends from ground at RA3I3 by way of the elements CIS1, RA353 and the upper winding of R350 to battery. At RA352, the relay R350 interrupts a point in the above-noted alternative circuit for energizing R330. At RA354, the relay R350 opens a point in the above-traced circuit for energizing the horizontal magnet M330. At RA3S5, the relay R350 completes a circuit extending by way of C114 for energizing the pair of magnets including M385 and corresponding to the magnets 91 and 02 of the mechanism shown in Fig. 2. As explained above, the energization of these magnets causes the actuating member associated with the elements 191 and SW155 to be moved in its third direction, there- 'by to actuate the contact closing member 191 into engagement with the springs bearing SC152 and SC153. There results the connection of the conductors C142, C143 and C180 to the conductors C1 46, C141 and C148, respectively, of the called line 145. At RA351, the series relay R350, upon operating, applies ground to C180, which is extended by way of S0153 and S0154 to C148 of the called line 145, thereby to mark the called line as busy in the bank contacts of the other final selector switches in which the conductors of this line are multipled.

When the switch mechanism S144 operates in the above-described manner to connect the conductors C142 and C143 to the line conductors of the called subscribers line H5, a path is completed for applying ring-back tone current to the loop extending to the calling subscribers substation A and ringing current to the loop extending to the called subscribers substation B. The path of the ringing current extends from one .side of the ringing current generator at R0342 by way of the elements RA341, CH2, SC152, SC150, CH8, the signal device bridged across C1 46 and C141 at the called substation, C141, S0149, S0151, CH3, RA344, RC345, C165, the lower winding of R340 and C166 to the opposite side of the ringing current generator. A portion of this current is by-passed through the receiver at the calling partys substation by way of the condenser 182, the lower side of the loop including C114, the receiver at the called partys substation, the upper side of the loop including C113, through the left-hand winding of the impedance element 141 to ground. It is noted that the ring cut-01f relay R340 is so constructed that it does not operate in response to the energization of its lower winding by the alternating ringing current.

When the called party answers, a direct current path is bridged across C146 and C141 at the called substation, thereby to complete a direct current circuit for energizing the lower winding of R340, which circuit is identical with that traced above and traversed by the ringing current, and extends from the grounded side of the ringing current generator at R0342 to the ungrounded side of the ringing current generator at C166 connected to the lower terminal of the lower winding of R340. In response to the energization of its lower winding, R340 partially operates to complete the X contacts associated with RA341, thereby to cause the energization of its upper winding over an obvious circuit. When this upper winding is energized, R340 fully operates to interrupt, at its armatures RA341 and RA344 and their respective associated contacts R0342 and R0345, the application of ringing current and ring-back tone current to the loops extending, respectively, to the called and calling subscribers substations. At these last-mentioned armatures and their respective associated contacts R0343 and RC346, the calling line is connected to the called line so that a conversational circuit is completed between the calling telephone A and the called telephone B. It is pointed out that talking battery is applied to the loop extending to the called subscribers substation through the windings of the impedance element 141, which windings are connected in series with the exchange battery across C138 and C139. Similarly,

talking battery is applied to the loop extending to the calling subscriber's substation through the windings of R300. The system remains in this condition until the connection is cleared out at the calling subscriber's substation.

If the called party hangs up first, nothing occurs, the entire switch train being held operated by virtue of the fact that R300 is maintained energized over the closed loop extending to the calling substation and R310 is held operated by R300, thereby to maintain ground on C115 and C161. Ground on C115 maintains the switches S103 and S104 operated, and ground on C161 holds R340, R350 and M385 operated. Thus, the switch S140 is held in its operated condition until the calling party hangs up.

When the calling party hangs up his receiver, to interrupt the circuit holding R300 energized, this relay restores to open the operating circuit for R310. The hold relay R310 upon restoring RA311 and RA312, removes ground from C108 and C115, thereby to initiate the release of the switches S103 and $104 in the exact manner described above in connection with the release of a connection established to a busy line. At RA313, the relay R310 opens the holding circuits for R340 and R350, causing these relays to restore. Restoration of R350 causes the deenergizaticn of the two magnets comprising M385. Restoration of RA314, embodied in R310, completes the circuit for energizing the interrupter relay R310. Operation of the relay R310 causes the magnet M390 to be alternately energized and de-energized to drive, in cooperation with its associated pawl the carriage of the last-mentioned mechanism to its normal or home position. When this occurs the carriage member associated with the elements 191 and SW155 is released and returns to normal and the springs NS158 and ONS151 are restored to normal. Thus, the switch train is entirely released and the equipment involvedtherein is conditioned for further use.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein, and it is contemplated to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

I claim:

1. In a signalling system, a plurality of lines, an automatic switch having access to said lines, and an incoming line to said switch; said switch comprising a movable member, means for moving said member a predetermined distance in one direction thereby to select a particular group of said plurality of lines, means for moving said member a predetermined distance in a second direction, means operable during said last-mentioned movement for testing the condition of a particular line in said selected group of lines, means for moving said member in a third direction, and means responsive to said last-mentioned movement for connecting said incoming line to said particular line.

2. In a signalling system, a plurality of lines, each of said lines being marked as idle or busy, an automatic switch having access to said lines, and an incoming line to said switch; said switch comprising a movable member, means for movareas ing said member a predetermined distance in one direction thereby to select a group of said plurality of lines, means for moving said member in a second direction, means operable during said last-mentioned movement for testing the condition of the lines in said selected group of lines,

-means for moving said member in a third direction when the first idle line in said selected group of lines is tested, and means responsive to said lest-named movement for connecting said incoming line to said idle outgoing line.

3. In a signalling system, a plurality of lines, each of said lines being marked as idleor busy, an automatic switch having access to said lines. and an incoming line to said switch; said switch comprising a movable member, impulse responsive means, means responsive to the operation of said impulse responsive means for moving said member a predetermineddistance in one direction thereby to select a group of said plurality of lines, means for moving said member in a second direction, means operable during said last-named movement for testing the condition of the lines in said selected group of lines, means for moving said member in a third direction when the first idle line in said selected group of lines is tested, and means responsive to said last-named movement for connecting said incoming line to said idle outgoing line.

4. In a signalling system, a plurality of lines, each of said lines being marked as idle orbusy, an automatic switch having access to said lines, and an incoming line to said switch; said switch comprising a movable member, impulse responsive means, means responsive to the operation of said impulse responsive means for moving said member a predetermined distance in one direction thereby to select a group of said plurality of lines, means automatically operable immediately following said group selection -for moving said member in a second direction, means operable during said last-named movement for testing the condition of the lines in said selected group of lines, means for moving said member in a third direction when the first idle line in said selected group of lines istested, and means responsive to said last-named" movement for connecting said incoming line'to said idle outgoing line.

5. In a signalling system, a plurality of lines, each of said lines being marked as idle or busy, an automatic switch having access to said lines, and an incoming line to said switch; said switch comprising a movable member, impulse responmember a predetermined distance in one direction thereby to select a group of said plurality of lines, means responsive to the further operation of said impulse responsive means for moving said member a predetermined distance in a second direction, means operable during said lastnamed movement for testing the condition of a particular line in said selected group of lines, means for moving said member in a third direction when said particular line in said selected group 01 lines is tested, and means responsive to said last-named movement for connecting said incoming line 'to said particular line.

6. In a signalling system, a plurality of lines, an automatic switch having access to said lines, and an incoming line to said switch; said switch comprising a member having a normal position and movable in three directions successively to select a particular group of said plurality of lines, test the condition of a particular line of said selected group of lines and connect said incoming line to said particular line, means for moving said member step-by-step in one of said directions, means for moving said member step-bystep in a second of said directions, said firstnamed means being inoperative to move said member when said member is in its normal position, means for energizing said second-named means thereby to actuate said member in said second of said directions and to render said firstnamed means operative to actuate said member, means for thereafter repeatedly energizing said first-named means to cause the stepping of said member in said one of said directions, means for thereafter successively energizing said secondnamed means to cause the stepping of said member in said second direction, and means for finally moving said member in the third of said directions.

7. In a signalling system, a plurality of lines, an automatic switch having access to said lines, and an incoming line to said switch; said switch comprising a member having a normal position and movable in three directions successively to select a particular group of said plurality lines, test the condition of a particular line of said selected group of lines and connect said incoming line to said particular line, means for moving said member step-by-step in one of said directions, means for moving said member step-bystep in a second of said directions, said firstnamed means being inoperative to move said member when said member is in its normal position, means responsive to the seizure of said switch over said incoming line for energizing said second-named means thereby to actuate said member in said second direction and to render said first-named means operative to actuate said member, means for thereafter repeatedly energizing said first-named means to cause the stepping of said member in said one direction, means for thereafter repeatedly energizing said secondnamed means to cause the stepping of said member in said second direction, and means for finally moving said member in the third of said directions.

8. In a signalling system, a plurality of lines, an automatic switch having access to said lines, and an incoming line to said switch; said switch comprising a member having a normal position and movable in three directions successively to select a particular group of said plurality lines, test the condition of aparticular line in said selected group of lines and connect said incoming line to said particular line, impulse responsive means, means for moving said member step-bystep in one of said directions, means for moving said member step-by-step in a second of said directions, said first-named means being inoperative to move said member when said member is in its normal position, means for energizing said second-named means thereby to actuate said member one step in said second direction and to render said first-named means operative to actuate said member, means for thereafter repeatedly energizing said first-named means in accordance with the operation of said impulse responsive means to cause the stepping of said member in said one direction, means for thereafter repeatedly energizing said first-named means to cause the stepping of said member in said second direction, and means for finally moving said member in the third of said directions.

9. In a signalling system, a plurality of lines, an automatic switch having access to said lines,

and an incoming line to said switch; said switch comprising a member having a normal position and movable in three directions successively to select a particular group of said plurality lines, test the condition of a particular line in said selected group of lines and connect said incoming line to said particular line, impulse responsive means, means for moving said member step-bystep in one of said directions, means for moving said member step-by-step in a second of said directions, said first-named means being inoperative to move said member when said member is in its normal position, means for energizing said second-named means thereby to actuate said member one step in said second direction and .to render said first-named means operative to actuate said member, means for thereafter re-,

peatedly energizing said first-named means in accordance with the operation of said impulse responsive means to cause the stepping of said member in said one direction, means for thereafter repeatedly energizing said second-named means in accordance with the further operation of said impulse responsive means to cause thestepping of said member in said second direction, and means for finally moving said member in the third of said directions.

10. In a signalling system, a plurality of lines, an automatic switch having bank contact sets at which said lines terminate, said contact sets being arranged in levels, and each thereof including a test contact and a pair of normally open line contacts, each of said levels corresponding to a group of said plurality of lines, a line incoming to said switch; said switch comprising a test wiper biased to a normal position and operable to an oiI-normal position wherein it is engageable with the test contacts-of its associated level, a movable actuating member, means for moving said actuating member to one position to operate one of said test wipers to its off-normal position, means for operating said actuating member to a second position to cause said one operated test wiper to engage the test contact of a particular contact set in one of said levels, thereby to determine the idle or busy condition of the line terminating at said particular contact set, and means for closing the pair of open line contacts included in said particular contact set in the event said last-mentioned line is idle, and means for preventing the operation of said last-mentioned means in the event said last-mentioned line is busy.

11. In a signalling system, a plurality of lines, anautomatic switch having bank contact sets at which said lines terminate, said contact sets being arranged in levels, and each thereof including a test contact and a pair of normally open line contacts, each of said levels corresponding to a group of said plurality of lines, a line incoming to said switch; said switch comprising a test wiper and a contact closing member associated with each of said levels, each of said test wipers being biased to a normal position and being operable to an off-normal position wherein it is engageable with the test contacts of its associated level, each of said-contact closing members being biased to a normal position and being operable to an off-normal position to close a selected'pair of said line contacts, a movable actuating member, means for moving said actuating member to one position to operate one of said test wipers to its oil-normal position,

means for operating said actuating member to a second position to cause said one operated test wiper to engage the test contact of a particular contact set in one of said levels, and means for moving said actuating member to a third position to operate the contact closing member associated with said one level to its oil-normal position.

12. An antomatic switch comprising a. level of contact sets, each of said contact sets including a test contact, a carriage movable in a first direction over said level of contact sets, a test wiper mounted on said carriage, said test wiper being biased to a normal position away from the test contacts of said level and being operable to anofi-normal position wherein it is engageable with the test contacts of said level, a member carried by said carriage and movable over said level of contact sets in a second direction, means for moving said member in said second direction thereby to move saidtest wiper to its off-normal position, and means for moving said carriage and said test wiper mounted thereon in said first direction to cause said test wiper successively to engage the test contacts of said contact set level.

13. An automatic switch comprising a level of contact sets, each of said contact sets including a test contact, a carriage movable in a first lineal direction over said level of contact sets, a test wiper mounted on said carriage, said test wiper being biased to a normal position away from the test contacts of said level and being p le to an off-normal position wherein it is engageable with the test contacts of said level, a member carried by said carriage and movable over said level of contact sets in a second lineal direction, means for moving said member in said second lineal direction thereby to move said test wiper to its off-normal position, and means for moving said carriage and said test wiper mounted therein in said first lineal direction to cause said test wiper successively to engage the test contacts of said contact set level.

14. An automatic switch comprising a bank of contact sets, said contact sets being arranged in levels and each thereof including a test contact, a test wiper associated with each of said levels, each of said wipers being biased to a normal position away from the test contacts of the associated level and being operable to an offnormal position wherein it is engageable with the test contacts of the associated level, a member movable in two directions, means for moving said member in one of said directions, means responsive to the successive movement of said member predetermined distances in said one of said directions for successively operating said test wipers to their respective off-normal positions, said means being operative to cause each wiper to return to its normal position as the succeeding wiper is operated to its oil-normal position, and means for moving all of said test wipers and said member in the other of said two directions to cause any operated test wiper successively to engage the test contacts of its associated level,

15. An automatic switch comprising a bank of contact sets, said contact sets being disposed in substantially the same plane and being arranged in levels each comprising a plurality of said contact sets, each of said contact sets including a test contact, a test wiper associated with each of said levels, each of said wipers being biased to a normal position away from the test contacts of the associated level and being operable to an oiT-normal position wherein it is engageable with the test contacts of the associated level, amemceeding wiper is operated to its cit-normal position, and means for moving all of said test wipers and said member in the other of said two directions to cause any operated test wiper successively to engage the test "contacts oi its associated level.

16. Ari-automatic switch comprising a bank of,

contact sets, said contact sets being arranged in levels each comprising a plurality of said contact sets, each of said contact sets including a test contact, a test wiper associated with each of said levels, each of said wipers being biased to 9, normal position away from the test contacts of the associated level and being operable to an of!- normal position wherein it is engageable with the test contacts of the associated level, a member movable in two directions, a plurality of projections extending from said member and individually corresponding tosaid levels, means comprising a magnet and a ratchet and pawl mechanism for moving .said member step by step in one of said direction-r, means disposed in the path 01 said projections during such movement and succ'essively engaged by said projections for successively operatiugsaid test wipers to their respective off-normal positions, said last-named means being operative to cause each wiper to return to its normal position as the succeeding wiper is operated to its oil-normal position, and means for moving all of said test wipers and said member in the other of said two directions to cause any operated test wiper successively to engage the test contacts of its associated. level.

17. An automatic switch comprising a bank of contact sets, said contact sets being arranged in levels each comprising a plurality of said contact sets, each 01' said contact sets including a test contact, a test wiper associated with each of said levels, each of said test wipers being biased to a normal position away from the test contacts of the associated level and being operable to an oil-- normal position wherein it is engageable with the test contacts of the associated level, a member movable in two directions, means for moving said member in one of said directions, means responsive to the movement of said member a predetermined distance in said one direction for operating a predetermined one of said wipers to its ofinormal position, means responsive to a predetermined continued movement of said member in the same direction for causing said predetermined one of said wipers to return to its normal position and for operating a second of said wipers to its oil-normal position, and means for moving all of said test wipers and said member in the other of said two directions to cause any operated test wiper successively to engage the test contacts of its associated level.

18. An automatic switch comprising a bank of contact sets, said contact sets being disposed in oil-normal position wherein it is engageable with the test contacts of the associated level, a member movable in two directions, means for moving said member in one .of said directions, means responsive to the movement of said member a premoving all of said test wipers and said member in the other of said two directions to cause any operated test wiper successively to engage the test contacts of its associated level.

19. An automatic switch comprising a bank of contact sets, said contact sets being arranged in levels each comprising a plurality of said contact sets, each of said contact sets including a test contact, a test wiper associated with each of said levels, each of said test wipers being biased to a normal position away from the test contacts of the associated level and being operable to an off-normal position wherein it is engageable with the test contacts of the associated level, a member movable in two directions, means including a motor magnet and a ratchet and pawl mechanism for moving said member step by step in one of said directions, a plurality of projections s aced along said member and individually corresponding to said levels of contact sets, means disposed in the path of one of said projections and engaged thereby during a predetermined step of means disposed in the path and engaged by a' succeeding one of said projections during a succeeding step for operating a second of said wipers to its ofi-normal position, and means for moving all of said test wipers and said member in the other of said two directions to cause any operated test wiper successively to engage the test contacts of its associated level.

20. An automatic switch comprising a bank of contact sets, said contact sets being arranged in levels each comprising a plurality of said contact sets, each 01' said contact sets including a test contact, a carriage movable in one direction over said bank of contact sets, rocker arms mounted on said carriage, each or said arms being associated with one of said levels, a test wiper mounted on each of said rocker arms, each of said wipers being biased to a normal position away from the test contacts of the level associated with the rocker arm upon which it is mounted and being operable by its associated rocker arm to an ofinormal position wherein it is engageable with the test contacts of the associated level, a member carried by said carriage and movable over said bank of contact sets in a second direction, projections extending from and spaced along said member, each of said projections being adapted to engage, during movement of said member in said second direction, a single one of said rocker arms, thereby to operate the wiper mounted thereon to its oil-normal position, means for moving said member in said second direction, said projections being so arranged that'during movement of said member in said second direction successive ones thereof engage and then disengage their respective associated rocker arms, and means for moving said carriage to cause any operated test wiper successively to engage the test contacts of.

the level associated with the rocker arm upon which it is mounted.

21. An automatic switch comprising a bank of contact sets, said contact sets being arranged in levels each comprising a plurality of said contact sets, each of said contact sets including a test contact, a carriage movable in one direction over said bank of contact sets, rocker arms mounted on said carriage, each of said arms being associated with one of said levels, a test wiper mounted on each of said rocker arms, each of said wipers being biased to a normal position away from the test contacts of the level associated with the rocker arm upon which it is mounted and being operable by its associated rocker arm to an offnormal position wherein it is engageable with the test contacts of the associated level, a member carried by said carriage and movable over said bank of contact sets in a second direction, projections extending from and spaced along said member, each of said projections being adapted to engage, during movement of said member in said second direction, a single one of said rocker arms, thereby to operate the wiper mounted thereon to its oil-normal position, means comprising a motor magnet and a ratchet and pawl mechanism for moving said member step by step in said second direction, said projections being so arranged that at the conclusion of each step by said member one of said projections engages its associated rocker arm and the preceding projection is just disengaged from its associated rocker arm, and means for moving said carriage to cause any operated test wiper successively to engage the test contacts of the level associated with the arm upon which it is mounted.

22. An automatic switch comprising a bank of contact sets, said contact sets being arranged in levels each comprising a plurality of said contact sets, each of said contact sets including a test contact, a carriage movable in one direction over said bank of contact sets, rocker arms mounted on said carriage, each of said arms being associated with one of saidlevels, a test wiper mounted on each of said rocker arms, each of said wipers being biased to a normal position away from the test contacts of the level associated with the rocker arm upon which it is mounted and being operable by its associated rocker arm to an onnormal position wherein it is engageable with the test contacts of the associated level, a member carried by said carriage and movable over said bank of contact sets in a second direction, projections extending from and spaced along said member, each of said projections being adapted to engage, during movement of said member in said second direction, a single one of said rocker arms, thereby to operate the wiper mounted thereon to its off-normal position, means comprising a motor magnet and a ratchet and pawl mechanism for moving said member step by step in said second direction, said projections being so arranged that at the conclusion of each step of said member one of said projections engages its associated rocker arm and the preceding projection is just disengaged from its respective associated rocker arm, and means comprising a magnet and an escapement mechanism for moving said carriage step by step to cause any operated test wiper successively to engage the test con-- tacts of the level associated with the arm upon which it is mounted.

23. An automatic switch comprising a bank of contact sets, said contact sets being arranged in levels each comprising a plurality of set contact sets, each of said contact sets including a test contact, a carriage movable in one direction over said bank of contact sets, rocker arms mounted on said carriage, each of said arms being associ-' ated with one of said levels, a test wiper mounted on each of said rocker arms, each of said wipers being biased to a normal position away from the test contacts of the level associated with the rocker arm'upon which it is-mounted and being operable by its associated rocker arm to an oilnormal position wherein it is engageable with the test contacts of the associated level, a member carried by said carriage and movable over said bank of contact sets in a second direction, projections extending from and spaced along said member, each of said projections being adapted to engage, during movement of said member in said second direction, a single one of said rocker arms, thereby to operate the wiper mounted thereon to its off-normal position, means comprising a motor magnet and a ratchet and pawl mechanism for moving said member step by step in said second direction, said projections being so arranged that at the conclusion of each step of said member one of said projections engages its associated rocker arm and the preceding projection is just disengaged from its associated rocker arm, means comprising a magnet and an escapement mechanism for moving said carriage step by step to cause any operated test wiper successively to engage the test contacts of the level associated with the arm upon which it is mounted. and control means for repeatedly energizing said first-named magnet and then said second-named magnet.

24. An automatic switch comprising a level of contact sets, each of said contact sets including a pair of normally open line contacts, a contact closing member associated with said level of contact sets, said contact closing member being biased to a normal position away from the contacts of the said level and being operable to an off-normal position to close the contacts of a selected pair of said line contacts, an actuating member, means for moving said actuating member in one direction to condition it to operate said contact closing member, means for moving said actuating member and said contact closing member in a second direction such that said contact closing member travels along said contact set level, and means for moving said actuating member in a third direction to operate said contact closing member to its off-normal position.

25. An automatic switch comprising a level of contact sets, each of said contact sets including a pair of normally open line contacts, a contact closing member associated with said level of contact sets, said contact closing member being biased to a normal position away from the contacts of the said level and being operable to an off-normal position to close the contacts of a selected pair of said line contacts, an actuating member, means for moving said actuating member lineally in one direction to condition it to operate said contact closing member, means for moving said actuating member and said contact closing member lineally in a second direction such that said contact closing member travels along said contact set 'level, and means for moving said actuating member lineally in a third direction to operate said contact closing member to its oil?- normal position.

26. An automatic switch comprising a bank of contact sets, said contact sets being arranged in levels each comprising a plurality of said contact sets, each of said contact sets including a crable to an off-normal position to close the contacts of a selected pair of said line contacts, an actuating member, means for moving said actuating member in one direction, means responsive to the successive movement of said'actuating member predetermined distances in said one direction for conditioning it to operate successive ones of said contact closing members, said last-named means being so arranged that said actuating member is conditioned to actuate only one of said contact closing members when moved any one of said predetermined distances, means for moving said actuating member and said contact closing members in a second direction such that said contact closing members travel along their respective associated contact set levels, and means for moving said actuating member in a third direction to operate one of said contact closing members to its off-normal position.

27. An automatic switch comprising a bank of contact sets, said contact sets being disposed in substantially the same plane and being arranged in levels each comprising a plurality of said contact sets, each of said contact sets including a pair of normally open line contacts, a contact closing member associated with each level of contact sets, each of said contact closing members being biased to a normal position away from the contacts of its associated level and being operable to an ofi-normal position to close the contacts of a selected pair of said line contacts, an actuating member, means for moving said actuating member in one direction, means'responsive to the successive movement of said actuating member predetermined distances in said one direction for conditioning it to operate successive ones of said contact closing members, said last-named means being so arranged that said actuating member is conditioned to actuate only one of said contact clos'ng members when moved any one of said predetermined distances, means for moving said actuating member and said contact closing members in a second direction such that said contact closing members travel along their respective associated contact set levels, and means for moving said actuating member in a third direction to operate one of said contact closing members to its oif-normal position.

28. An automatic switch comprising a bank of contact sets, said contact sets being arranged in levels each comprising a plurality of said contact sets, each of said contact sets including a pair of normally open line contacts, a contact closing member associated with each level of contact sets, each of said contact closing members being biased to a normal position away from the contacts of its associated level and being operable to an oilnormal position to close a selected pair of said line contacts, an actuating member, means for moving said actuating member in one direction, means responsive to the movement of said actuating member a predetermined distance in-said one direction for conditioning said actuating member to operate one of said contact closing members, said last-named means being so arranged that a predetermined continued movement of said actuating member in-the same direction renders said actuating member inoperative to operate said one contact closing member and conditions said actuating member to operate a second of said contact closing members, means for moving said actuating member and said contact closing members in a second direction such that said contact closing members travel along their respective contact set levels, and means for moving said actuating member in a third direction to operate one of said contact closing members to its off-normal position.

29. An automatic switch comprising a bank of contact sets, said contact sets being disposed in substantially the same plan and being arranged in levels each comprising a plurality of said con-. tact sets, each of said contact sets including a pair of normally open line contacts, a contact closing member associated with each level of contacts, each of said contact closing members being biased to a normal position away from the contacts of its associated level and being operable to an off-normal position to close a selected pair of said line contacts, an actuating member, means for moving said actuating member in one direction, means responsive to the movement of said actuating member a predetermined distance in said one direction for conditioning said actuating member to operate one of said contact closing members, said last-named means being so arranged that a predetermined continued movement of said actuating member in the same direction renders said actuating member inoperative to operate said one contact closing member and conditions said actuating member to actuate a second of said contact closing members, means for moving said actuating member and said. contact closing members in a second direction such that said contact closing members travel along their respective contact set levels, and means for moving said actuating member in a third direction to operate one of said contact closing members to its off-normal position.

30. An automatic switch comprising a bank of contact sets, said contact sets being arranged in levels each comprising a plurality of said contact sets, each of said contact sets including a pair of normally open line contacts, a contact closing member associated with each level of contact sets, each of said contact closing members being biased to a normal position away from the contacts of its associated level and being operable to an off-normal position to close a selected pair of said line contacts, an actuating member movable in one direction and having projections extending therefrom, each of said projections being movable, during movement of said actuating member in said one direction, to a position opposite one of said contact closing members, means for moving said actuating member in said one direction, said projections being so arranged that during movement of said actuating member in said one direction successive ones thereof stand opposite their respective associated contact closing members, means for moving said contact closing members and said actuating member in a second direction such that said contact closing members travel along their respective associated contact levels, and means for moving said actuating member in a third direction to cause any projection standing opposite its associated contact closing member to operate the same to its oiT-normal position.

31. An automatic switch comprising a bank of contact sets, said contact sets being arranged in levels each comprising a plurality of said contact sets, each of said contactsets including a pair of normally open line contacts, a carriage movable in one direction over said bank of contact sets, contact closing members mounted on said carriage and individually associated with said levels of contact sets, each of said contact said second direction, said projections being so arranged that during movement of said actuating member in said second direction successive ones thereof stand opposite their respective associated contact closing members, means for moving said carriage in said one direction such that said contact closing members travel along their respective associated contact levels, and means for moving said actuating member in a third direction to cause any projection standing opposite its associated contact closing member to operate the same to its ofi-normal position. a

32. An automatic switch comprising a level of contact sets, each of said contact sets including a test contact and a pair of normally open line contacts, a test wiper associated with said level,

said test wiper being biased to a normal position away from the test contacts of said level and being operable to an oil-normal position wherein it is engageable with the test contactsof the associated level, a contact closing member associated with said level of contact sets, said contact closing member being biased away from the contacts of the said level and being operable'to an oil-normal position to close a selected pair of said line contacts, an actuating member, means for moving said actuating member in one direction to condition it to operate said contact closing member and to operate said test wiper to its oil-normal position, means for moving said actuating member, said test wiper and said contact closing member in a second direction thereby to cause said test wiper successively to engage the test contacts of said contact level, and means for moving said actuating member in a third direction to operate said contact closing member to its off-normal position.

33. An automatic switch comprising a bank of contact sets, said contact sets being arranged in levels each comprising a plurality of said contact sets, each of said contact sets including a test contact and a pair of normally open line contacts, a test wiper and a contact closing member associated with each of said levels of con- I tacts, each of said wipers and members being biased to a normal position away from the corresponding contacts of the contact sets in the associated level and being operable to an oil'- normal position wherein it is engageable with the said corresponding contacts, an actuating member movable in one direction and having two sets of projections extending therefrom, each of the projections of one set being movable, during movement of said actuating member in said one direction to move one of said test wipers to its off-normal position and each of the projections of the other set being movable during movement of said actuating member to a position opposite one of said contact closing members, means for moving said actuating member in said one direction, the projections of said one set being so arranged that during movement of said actuating member in said one direction successive ones of said test wipers are moved to their respective ofi-normal positions and the projections of said other set being so arranged that during movement of said actuating member in said one direction successive ones thereof stand opposite their respective associated contact closing members, means for moving said actuating member, all of said test wipers and all of said contact closing members in a second direction to cause any operated test wiper successively to engage the test contacts of the contact sets in its associated level, and'means for moving said actuating member in a third direction to operate the contact closing member associated with any operated test wiper to its oil-normal position,

34. ,An automatic switch comprising a bank of contact sets, said contact sets being arranged in levels each comprising a plurality of said con,- ,tact sets, each of said contact sets including a test contact and a pair of normally open line contacts, a test wiper and a contact closing member associated with each oi. said levels of contacts, each of said wipers and members being biased to a normal position away from the corresponding contacts of the contact sets in the associated level and being operable to an off-normal position wherein it is engageable with the said corresponding contacts, an actuating member, means for moving said actuating member in one direction, means responsive to the movement of said actuating member predetermined distances in said one direction for operating successive ones of said test wipers to their respective oiinormal positions and for conditioning successive ones of said contact closing members to be operated by said actuating member to their respective oilnormal positions, said last-named means being so arranged that each wiper-is returned to its normal position as the successive wiper is operated to its off-normal position and said actuating member is rendered inoperative to operate each contact closing member as the succeeding contact closing member becomes conditioned to be operated thereby, means for moving said actuating member, all of said test wipers and all of said contact closing members in a second direction to cause any operated test wiper successively to engage the test contacts of the contact sets in its associated level, and means for moving said actuating member in a third direction to operate the contact closing member associated with any operated test'wiper to its ofi-normal position.

35. Switching apparatus comprising a plurality of switching units each including a movable circuit controlling element, a member having a normal position and movable to an ofi-normal position to actuate said elements, said elements normally being non-responsive to movement of said member, means for selectively associating said elements with said member to be actuated 9 CERTIFICATE OF CORRECTION. Patent No. 2,1h5,589. January 10, 1959. 4

JOHN wIcKs.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: PagelZ, second column, line 7, claimlZ, for "antomatic" read automatic; line 39, claim 15, for "therein" read thereon; page 1h, first column, line 75, claim 25, for the word "set" read said; page 15 second column, line 12, claim 29, for "plan" read .plane and that thesaid Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office. I

Signed and sealed this 21st day of February, A., D. 1959.

' Van Arsdale. Actin 8riesioner of Patents.