US2298910A - Automatic switch - Google Patents

Description

Oct. 13, 1942. B. D. wn |s AUTOMATIC SWITCH Original Filed Feb. 7, 1941 7 Sheets-Sheet l III E GI INVENTOR. BERNARD 0. WILUS AT T0 RNE Y8 Oct. 13, 1942. I B. D. WILLIS AUTOMATIC SWITCH Original Filed Feb. 7, 1941 '7 Sheets-Sheet 2 N9 ot IN V EN TOR. BERNARD D. WILLIS ATTORNEYS Oct. 13, 1942. B. D. WILLIS AUTOMATIC SWITCH Original Filed Feb. '7, 1941 7 Sheets-Sheet 5 #2 m: $2 m w: m:

'8 IN VEN TOR. BERNARD D.WILL|S 1942- B. D. WILLIS 2,298,910

AUTOMATI C SWITCH Original Filed Feb. 7, 1941 7 SheetsSheet 5 FIGS 15B INSULATION INSULATION INSULATION 20B 3 3 INSULATION INSULATION I 858 4'2 SR INSULATION TOR. BERNARD D. WILLIS ATTORNEYS Patented Oct. 13, 1942 AUTOMATIC SWITCH Bernard D. Willis, Oak Park, Ill., assignor to Associated Electric Laboratories, Inc., Chicago, Ill., a corporation of Delaware Original application Februar 7, 1941, Serial No. 377,835. Divided and this application August 23, 1941, Serial No. 408,053

9 Claims.

The present invention relates to automatic switches and more particularly to automatic switches of an improved type adapted for use in automatic telephone systems of the character of that disclosed in U. S. Patent No. 2,222,131, Bernard D. Willis, granted November 19, 1940. The present application is a division of the copending application of Bernard D. Willis, Serial No. 377,835, filed February '7, 1941.

In an automatic telephone system of the char acter of that disclosed in the Willis patent the subscriber-controlled switching apparatus provided for setting up connections between the various subscriber lines is so connected and arranged that it may be selectively controlled by a single impulse of variable length or time duration, as contrasted with conventional subscribercontrolled switching apparatus which is selectively controlled by a variable series of impulses of equal length or time duration.

While the telephone system disclosed in the Willis patent is thoroughly satisfactory in operation and entirely adequate to handle the traffic in a small exchange, such as a private automatic branch exchange, it is not of sulficiently flexible connection and arrangement to handle the trafiic in a large exchange, such as a central automatic exchange.

Accordingly, it is an object of the present invention to provide an improved automatic telephone system of the character noted, which is so connected arranged that it is sufficiently flexible to handle the traffic in any exchange, regardless of the size of the exchange.

Another object of the invention is to provide 5 in an automatic telephone system, an improved selector capable of making both line group and individual line selections, which is selectively controllable by a single impulse of variable length or time duration.

Another object of the invention is to provide in an automatic telephone system, an improved connector capable of making both line group and individual line selections, which is selectively controllable by a plurality of single impulses of variable-length or time duration.

A further object of the invention to provide in an automatic switching system. an improved switching arrangement which is selectively operative a constant-speed-variable-time-interval A further object of the invention is to provide in an automatic switch of the type having prisecondary movements. improved arrangement for selectively controlling the primary movement of the switch in accordance with the time duration of a single impulse transmitted thereto and for selectively controlling the secondary movement of the switch automatically.

A further object of the invention is to provide in an automatic switch of the type having primary and secondary movements, an improved arrangement for selectively controlling both the primary and secondary movements of the switch in accordance with the time durations of two successive single impulses of variable time duration transmitted thereto.

A still further object of the invention is to provide an improved mechanical switch which is of simple and economical construction, and which is positive and reliable in operation.

In general, the objects set forth above are attained in accordance with the present invention by providing in a telephone system, a calling line, a called line, a calling device selectively operative repeatedly to transmit a plurality of single impulses of variable time duration over the calling line. and means including a plurality of tandem related switches adapted to be selectively controlled sequentially in accordance with the time durations of the impulses for setting up a connection between the calling line and the called line. More particularly, the switches are arranged in a switch train including a selector and a tandem related connector, the selector being so connected and arranged that it is responsive to a single impulse transmitted over the calling line to make a first selection in accordance with the time duration of a single impulse and then automatically to make a second selection, and the connector being so connected and arranged that it is responsive to first and second impulses transmitted over the calling line to make first and second selections respectively in accordance with the time durations of the and second impulses.

In accordance with one feature of the invention, both the selector and the connector constitute an automatic switch of the type having primary and secondary movements. The selector embodies means responsive to the transmission of a single impulse over an associated circuit for selectively controlling the primary movement thereof in accordance with the time duration of the single impulse and automatic means for selectively controlling the secondary move ment thereof, whereby the selector is first operated in its primary movement to select one of a plurality of groups of trunks accessible thereto, and is then operated automatically in its tion of the second impulse, whereby the connector is operated in its primary movement to select one of a plurality of groups of lines accessible thereto and is then operated in its secondary movement to select any individual one of the lines from the previously selected group of lines. The selector embodies busy control apparatus operative in the event all of the trunks in the previously selected group of trunks are busy; while the connector embodies line testing apparatus operative to test the idle or busy condition of the lines selected thereby and then operative to return busy tone current over the associated connection or to project ringing current over the selected line, depending respectively upon the busy or idle condition of the selected line. Finally, both the selector and the connector embody release apparatusresponsive both to the opening of the associated connection and to false dialing over the associated connection to effect the release thereof.

In accordance with another feature of the invention both the selector and the connector are selectively controlled sequentially in tandem over a calling subscriber line associated therewith by a unique calling device at the calling subscriber substation to which the calling line extends, this calling device being operative repeatedly to alter the condition of the calling line from a given condition and then to restore the calling line to the given condition after a predetermined variable time interval, or to transmit a single impulse of variable length or time duration over the calling line, wherein the time duration is directly controlled in accordance with the digit dialed on the calling device. More particularly, the time interval comprises one or more unit time intervals corresponding to the digit dialed on the calling device. 7

In accordance with a further feature of the invention both the selector and the connector embody a mechanical switch of unique construction and arrangement; which mechanical switch may be of either of two forms. A first form of the mechanical switch comprises a rectangular contact bank and'an associated wiper capable of both lateral and longitudinal movements in the respective primary and secondary movements thereof; while the second form of the mechanical switch comprises a semi-cylindrical contact bank and an associated wiper capable of both rotary and longitudinal movements in the respective primary and secondary movements thereof. Each of the switches comprises shift mechanism for selectively controlling both the primary and the secondary movements thereof; and clutch mechanism for selectively controlling both the amount of primary movement and the amount of secondary movement of the switch. Also, each of the switches is operatively associated with a continuously rotating drive shaft which is rotated at a substantially constant speed and comprises drive control mechanism including a cylindrical spiral connection, whereby both the primary movement and the secondary movement of each switch is elfected at a constant rate.

Thus, each movement of each switch is effected at a constant rate for a variable time interval, whereby each switch is operative upon a constant-speed-variable-time-interval basis.

Further features of the invention pertain to the particular arrangement of the mechanical elements of the switches, whereby the above-outlined and additional operating features are attained.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention, both as to its organization and method of operation, to-

. gether with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings, in which Figure l is a fragmentary plan view of one form of an automatic switch constructed and arranged in accordance with the present invention; Fig. 2 is a fragmentary and elevational view of the switch shown in Fig. 1; Fig. 3 is a fragmentary side elevational View of the switch shown in Figs. 1 and 2; Fig. 4 is a fragmentary plan view of a modified form of an automatic switch constructed and arranged in accordance with the present invention; Fig. 5 is a fragmentary side elevational view of the switch shown in Fig. 4; and Figs. 6 and 7, taken together, illustrate diagrammatically an automatic telephone system connected and arranged in accordance with the present invention.

Construction and operation of the first form of the automatic switch Referring now more particularly to Figs. 1 to 3, inclusive, of the drawings, there is illustrated a first form of an automatic switch It?!) embodying the present invention, which comprises a substantially U-shaped support IBI including a fiat bottom wall I92 and two longitudinally spacedapart upstanding end walls I93 and I04, and an operating shaft I05 suitably journaled in bearings provided in the end walls Hi3 and IE4. Also, the switch I00 comprises a longitudinally movable carriage I slidably supported upon two laterally spaced-apart guide rods I51 and IE8 arranged in substantially parallel relation and extending longitudinally between the end walls IE3 and IM of the support IIII. More particularly, two tubular bushings I139 and III! respectively surround the guide rods I91 and I98 and are respectively fixed in openings provided in the opposite sides of the carriage H35, thereby to facilitate longitudinal sliding thereof upon the guide rods I91 and I53 between the end walls I03 and IM.

The operating shaft I555 comprises an enlarged cylindrical section III disposed intermediate the ends thereof, which enlarged section III has a longitudinally extending spiral or helical groove I I2 cut in the outer surface thereof. Also, the enlarged section III of the operating shaft H35 carries a tubular member IIS on the outer surface thereof, a pin I I4 being fixed to the tubular member I I 3 and projecting into the spiral groove H2 cut in the outer surface of the enlarged section I II, for a purpose more fully explained hereinafter. The tubular member IIS comprises a sprocket wheel H5, a ratchet wheel H5 and an annular flange I I], the sprocket wheel H5 and the ratchet wheel H5 being separated by an annular groove IIB formed in the surface of the tubular member IE3 and the ratchet wheel II6 and the annular flange III being separated by an annular groove H9 formed in the surface of the tubular member H3.

The upper central portion of the carriage I96 has a substantially semicircular recess I formed therein, thereby to provide upstanding side walls disposed in the annular groove H8 formed in the tubular member HIS. Also, the carriage I95 comprises a laterally extending shelf I 2| having a longitudinally extending slot I22 formed therein. Further, the carriage IE6 carries two upstanding bifurcated lugs and I2 on the opposite sides thereof which are respectively arranged in straddling relation with the guide rods Ilil and tea. Two sprocket wheels I25 and I25 are rotatably mot Iced upon the guide rods It'll and I68, respecti y, the sprocket wheel I25 being arranged betue n one end of the tubular bushing IE9 and the lug and the sprocket wheel I25 being or anged between one end of the tubular bushing and the lug I24.

Further, the switch Hid comprises laterally movable slide I27 carrying a conta controlling member IilA in the form of a wi or set. At this point it is noted that the contwiper set ItA is of the bridging t while the line wipers thereof are not of the bridging type,

this arrangement being utilized for a purpose more fully explained hereinafter. The slide I2? comprises two side pieces IZQ and between which the individual wipers of the wiper set IElA are clamped, by two screws ISI, the individual wipers of the wiper set IQA being insulated from each other and from the slide l2? by interposed strips of insulation I32. Also, the slide I2! comprises a substantially T-shaned carrying piece I33 arranged in the slot I22 formed in the shelf l2! of the carriage I65, the stem of the carrying piece I33 being securely clamped to the Wiper set IIlA by the screws l3].

The head of the carrying piece I33 is securely clamped to an endless chain I34. comprising a plurality of individual links flexibly connected together, by an arrangement including a plate I35 and two screws I35. The endless chain I35 is arranged in meshing relation with the sprocket wheel H5, which constitutes a driving sprocket wheel, and the two sprocket wheels I25 and which constitute idler sprocket wheels. Further, the slide I21 carries two guide members IS'I arranged in spaced-apart relation which are utilized for a purpose more fully explained hereinafter. Also, the side pieces I23 and lit? of the slide I2! are respectively provided with guiding projections I38 and I39 adjacent the upper ends thereof which cooperate with the slot I22 provided in the shelf I2! of the carriage its in order positively to guide the lateral movement of the slide I2! with respect to the carriage It. Finally, the side pieces I29 and 539 of the slide I27 respectively carry contact control projections I49 and Iii adjacent the lower ends thereof, for a purpose more fully explained hereinafter.

Further, the switch I23 corn contact bank I42 suitably secured in a recess provided in the bottom wall I 32 of the support Ifil, the end wall IE4 of the sup ort lei having a connecting recess provided therein in order to facilitate placement and removal f the contact bank M2. lhe contact bank E42 comprises eleven laterally spaced-apart and longitudinally extending rows of contact sets, the first row of contact sets being indicated at Each row of contact sets comprises eleven individual conol wiper of the i tact sets, the first contact set in the first row of contact sets I43 being indicated at 25A. The individual rows of contact sets are suitably secured together by an arrangement comprising a number of laterally extending screws I 24. Also, the individual contacts in each contact set in each row of contact sets are insulated from each other by a plurality of longitudinally extending interposed strips of insula -cn I45 and H35, the insulating strip being centrally disposed with respect to the row of contact sets and constituting a guide strip.

Further, the switch Hill comprises an arrangement including a shift magnet 3 A for controlling the movements of the carri ge I88 and the slide IEI. The shift magnet 36A comprises a core Ml, a field element M3 and a movable armature 5%, the armature I53 being pivotally mounted on the outer end of the field element I48 by a pivot pin use. Also, the core It? carries an operating winding I5I and a copper sleeve I52, the copper sleeve I52 rendering the armature M9 slow to release after the operating winding IZI has been deenergized. The core It! is suitably secured to a bracket 5232 which in turn is suitably secured to the end wall of the support It! by an arrangement co; "ising two screws The armature E li is normally biased in a counterclockwise direction about the pivot pin the, as viewed in Fig. 2, by an arrangement including a coil spring extending between the armature I49 and the field element lit. The armature i 39 comprises an upwardly and outwardly extending finger 5-5 which normally pro- ,iects into the annular groove I59 formed in the outer surface of the tubular nier Also, the armature I69 comprises outwardly extending arm I53 which supports the outer end of a guide bar Iii'l, the guide bar 55? being substantially triangular cross-section. The inner end of the guide bar I5? is pivotally mounted by a pivot pin I58 to a bracket Ibo which in turn is suitably secured by an arrangement, including a screw I66, to the end wall I94 of the support I lI. At this point it is noted that the guide bar I 5? is adapted to be pivoted in a clockwise direction about the pivot pin 5 i, as viewed in Fig. 3, into engagement with one of the notches provided in the ratchet wheel it carried by the tubular member M3, for a purpose more fully explained hereinafter.

Further, the switch ets of indich springs d to the bottom wall 5 on s the ably seen:

of the support Iti and i sulated from each oth- '55- in the S t y :red to Izll and inindividual er, and the individual swch s or" switch springs 52A b. the bottom wall of the support sulated from each other. switch springs in the set of are suitably secured t a bracket fixed to the bottom wall of t. and insulated from each other. dividual switch sprin s other. Theset sw a first motion n rmal s" 'tch contact cont n low-er end of the ece slide or" consti a first motion limit ing with the contact control pr ried by the slide I21. The set of switch springs BIIA constitutes a second motion normal switch cooperating with the shelf I2I of the carriage I06; while the set of switch springs 10A constitutes a second motion limit switch cooperating with the shelf I2! of the carriage I06. Also, a set of switch Springs 35A is operatively associated with the armature I 39 of the shift magnet 30A, the individual switch springs of the set of switch springs 35A being suitably secured to the field element I 68 of shift magnet 39A. Further, the individual switch springs of the set of switch springs 35A are suitably insulated from each other and from the end wall I03 of the support IIlI.

Further the switch H38 comprises a driving arrangement including a go magnet 89A, a stop magnet 99A, a spiral leaf spring I62 and a drive shaft It A. Th spiral leaf spring I62 is wound around the enlarged section I II of the operating shaft I85, one end of the leaf spring I52 being secured to the enlarged section I I I and the other end of the leaf spring I62 being secured to a stud It i anchored to the end wall I04 of the support IIJI. The outer end of the operating shaft IE5 carries a tubular collar I65 slidably mounted thereon, a pin Ififi being fixed to the operating shaft Hi5 and arranged in a longitudinally extending 5101; I51 formed in the tubular collar N55. The outer end of the tubular collar I 65 carries an annular flange I68 formed of magnetic material. The go magnet 86A comprises an operating winding IE9 and a magnetic field element I'II the field element I19 being arranged in operative relation with respect to the annular flange I 58. Similarly, the stop magnet 98A comprises an operating winding HI and a magnetic field element I12, the field element I12 being arranged in operative relation with respect to the annular flange I68. The go magnet 80A i supported by a bracket I13 suitably secured to the end wall Ie I of the support IIlI while the stop magnet MBA is supported by a bracket I14 suitably secured to the end wall I85 of the support IUI. Further, a stub shaft I15 is suitably journaled in a bracket I16 which is suitably secured to the bracket I13. The inner end of the stub shaft I15 carries an annular drive plate I11 formed of resilient material, such as rubber, leather or the like, which cooperates with the annular flange I58. The outer end of the stub shaft I15 carries a bevel gear- I18 arranged in driven relation with respect to an associated bevel gear I19 carried by the drive shaft I5A. It is noted that the drive shaft I5A is common to a plurality of switches of the character of the switch IE and is suitably journaled in an external support I80. Preferably, the drive shaft IA is driven in a counterclockwise direction, as Viewed in Fig. 1, by a constant speed motor, not shown, such as a' synchronous motor, whereby the speed of rotation f the drive shaft I5A is maintained within extremely close limits. It is noted that the bevel gear I18 is arranged in constant meshing relation with the bevel gear I19, whereby the stub shaft I is constantly driven in a clockwise direction, as viewed in Fig. 2, by the drive shaft I5A.

At this point it is noted that the switch IIliI as a whole is supported in cooperating relation with the drive shaft ISA upon an external support, not shown, whereby the bevel gear I18 is arranged in meshing relation with the bevel gear I19, as previously noted. Also, the switch IOEI may be removed as a whole from its external support relative to the drive shaft IEA, thereby to facilitate replacement or repair thereof. Further, in this connection, it is pointed out that the contact bank I42 may also be supported externally, whereby the support IIJI of the switch IIIII may be moved relative thereto; on the other hand, the contact bank I62 may be fixed to the support I III of the switch IIiI! if desired.

When the switch I Eli is completely released the winding I69 of the go magnet 88A and the winding I1I of the stop magnet 99A are deenergized; the operating shaft I 05 is biased in a counterclockwise direction, as Viewed in Fig. 2, by the spiral leaf spring I62; and the stub shaft I15 is driven at a constant speed in the clockwise direction, as viewed in Fig. 2, by the constantly rotating drive shaft I5A. When the switch I0!) is thus completely released the tubular collar I65 occupies its retracted position toward the left, as viewed in Fig. 3, whereby the annular flange I68 completely disengages the annular drive plate I11. Also, at this time, the slide I21 occupies its completely retracted position toward the right, as viewed in Fig. 2, with respect to the carriage I96, thereby to retain operated the first motion normal switch A. Finally, at this time, the carriage IIJB occupies its completely retracted position toward the left, as viewed in Fig. 3, thereby to retain operated the second motion normal switch A.

In order to operate the switch IGI), thereby to cause the wiper set IEA to select a particular group or row of contact sets, the winding I69 of the go magnet 89A is first energized and retained energized for a corresponding given time interval, depending upon the speed of operation of the switch Ifiil relative to the speed of rotation of the stub shaft I15, this ven time interval comprising one or more unit time intervals, as explained mor fully hereinafter; at the conclusion of this given time interval the winding I69 of the go magnet 86A is deenergized and the winding I1I of the stop magnet 98A is energized. When the winding I69 of the go magnet 88A is thus energized the field element IIo thereof attracts the annular flange I68, thereby to cause the annular flange I58 to move toward the right, as viewed in Fig. 3, into frictional engagement with the annular drive plate I11, the pin and slot connection ItS-Ifii between the operating shaft I and the tubular collar I65 accommodating this movement of the tubular collar I65 and the annular flange I68 carried thereby. When the annular flange I68 is thus moved by the go magnet A into'frictional engagement with the annular drive plate I11 the operating shaft IE5 is rotated in a clockwise direction, as viewed in Fig. 2, with the stub shaft I15, thereby to cause the spiral leaf spring I 62 to be wound up.

At this time, the winding I5! of the shift mag- 7 net 30A is deenergized, whereby the armature I69 occupies its normal position, being biased in a counterclockwise direction about the pivot pin I50, as viewed in Fig. 2, by the coil spring I54. Accordingly, the finger I55 carried by the armature I59 is disposed in the annular groove IIS provided in the outer surface of the tubular member I I3, thereby positively to prevent longitudinal movement of the tubular member II3 along the outer surface of the enlarged section III of the operating shaft Hi5 at this time. Also, at this time, the outer end of the guide bar I51 supported by the arm I56 carried by the armature I 39 is disposed below the teeth in the ratchet wheel IIB carried by the tubular member II3,

thereby to permit rotation of the tubular member H3 at this time.

As the operating shaft I55 is rotated in a clockwise direction, as viewed in Fig. 2, at this time, the spiral groove IIZ cut in the outer surface of the enlarged section II I thereof acts upon the pin H4 carried by the tubular member II3, thereby to lock the tubular member H3 to the enlarged section III of the operating shaft IE5 for rotation therewith. Accordingly, the tubular member H3 is rotated with the operating shaft I05, thereby to cause the endless chain I35 to be rotated about the sprocket wheels I 55, I and IE6 in a clockwise direction, as viewed Fig. 2, the sprocket wheel I I5 acting as a driving sprocket wheel and the sprocket wheels H25 and I25 acting as idler sprocket wheels. At the endless chain I34 is rotated in a clockwise direction the lower portion thereof is moved from the right toward the left, as viewed in Fig. 2, thereby to cause the slide I2? to be moved in guided relation with respect to the slot I22 provided in the shelf I2I of the carriage its. As the slide I2! is moved from the right toward the left, as viewed in 2, the wiper set IdA is moved from its normal position at the right of the carriage Hi8 toward its off-normal position at the left of the carriage E65. As the slide I2? is thus moved it passes the outer ends of the various rows of contact sets without engagement therewith, whereby the wiper set I 8A is moved progressively to select the various groups or rows of contact sets in a continuous motion and at a uniform speed.

The speed of rotation of the operating shaft 35 is so proportioned relative to the diameter of the sprocket wheel I i5 and the lateral spacing between the rows of contact sets that, at the conclusion of a given unit time interval, the wiper set ItA occupies a position in longitudinal alignment with respect to the first row of contact sets Hi3; and at the conclusion of any number of unit time intervals between I and I! the wiper set 15A occupies a position in longitudinal alignment with respect to a corresponding row of contact sets. Thus, at the conclusion of the first, second, etc, and eleventh unit time intervals the wiper set liiA occupies positions respectively disposed in longitudinal alignment with respect to the corresponding first, second, etc., and eleventh rows of contact sets.

At the conclusion of the given time interval the winding I69 of the go magnet 86A is deenergized and the winding I?! of the stop magnet 99A is energized, as previously noted, whereupon the field element ITZ of the stop magnet 98A attracts the annular fiange I 55, causing the tubular collar I65 and the annular flange i653 carried thereby to be moved from the right toward the left, as viewed in Fig. 3, the pin and slot connection EEiiiIGI between the operating shaft I05 and the tubular collar I facilitating this movement. At this time the winding I'll of the stop magnet 90A is retained energized, thereby to retain the annular flange I58 out of engagement with the annular drive plate ill and in locked engagement with the field element I'IZ. As long as the winding I?! of the stop magnet 5313A is retained energized the annular flange I53 is ret ained in locked engagement with respect to the field element H2, thereby to retain the spiral leaf spring I52 in its wound condition and to prevent unwinding thereof and the consequent rotation of the operating shaft I in a counterclockwise direction, as viewed in Fig. 2, in a manner more fully explained hereinafter.

At the conclusion of the movement of the slide I21 from the right toward the left, as viewed in Fig. 2, with respect to the carriage I05, which motion constitutes the first motion of the switch I03, the winding I5I of the shift magnet 30A is energized. When the winding I5I of the shift magnet 30A is thus energized the armature IE9 is attracted and rotated in a clockwise direction about the pivot pin I59, as viewed in Fig. 2, against the bias of the coil spring I54. When the armature M9 is thus operated the finger I55 carried thereby is moved out of engagement with the annular groove IIS provided in the outer surface of the tubular member II3, thereby to unlock the tubular member I I3 for longitudinal movement along the outer surface of the enlarged section iii of the operating shaft I05. Also, when the armature 569 is thus operated the arm I55 carried thereby forces the outer end of the guide bar i5? into one of the notches provided in the ratchet wheel I it, thereby to lock the tubular member H3 against rotation with the operating shaft I85.

t this point it is noted that the winding i5i of the shift magnet 39A is energized substantially simultaneously with the deenergization of the winding 259 of the go magnet 83A and the energization of the winding I'Ii of the stop magnet A; whereby the outer end of the guide bar I5? is moved into engagement with one of the notches provided in the ratchet wheel H6 prior to the time that the annular fiange its is moved into locked engagement with the field structure I12 of the stop magnet 95A. During this brief interval of time the spiral leaf spring IE2 tends to unwind, thereby to rotate the operating shaft I95 in a counterclockwise direction, as viewed in Fig. 2. However, the spiral leaf spring IE2 is prevented from unwinding and the position of the operating shaft I55 is precisely centered by the action of the outer end of the guide bar I57 as it is forced by the arm I55 carried by the armature I 19 into one of the notches provided in the ratchet wheel II6. This arrangement not only positively prevents unwinding of the helical leaf spring I52, as previously explained, but it also positively insures that the wiper set IGA occupies a position in precise longitudinal alignment with respect to the selected row of contact sets.

Also, when the armature I29 of the shift magnet SUA is thus operated the set of switch springs 35A is operated for a purpose more fully explained hereinafter.

After the switch I86 has been operated in the manner described above, thereby to select one of the rows of contact sets, in order further to operate the switch I to select a particular contact set in the previously selected row of contact sets, the winding III of the stop magnet 90A is first deenergized and the winding I89 of the go magnet 83A is energized for a corresponding given time interval depending upon the speed of operation of the switch I relative to the speed of rotation of the stub shaft H5, this given time interval comprising one or more unit time intervals, as previously explained. At the conclusion of this given time interval the winding I65 of the go magnet 85A is deenergized and the winding I'II of the stop magnet 99A is energized. When the winding I'II of the stop magnet WA is thus deenergized the field element I72 releases the annular flange I68; and when the winding I69 of the go magnet 88A is thus energized the field element I'IU attracts the annular flange I68, thereby to clutch the annular flange I68 to the annular drive plate IT! in the manner previously explained; whereby the operating shaft IE is again rotated in the clockwise direction, as viewed in Fig. 2, with the stub shaft I15, thereby to cause the spiral leaf spring I62 to be further wound up.

At this time, the winding I5! of the shift magnet 30A is energized and the armature I49 occupies its operated position, thereby to retain the guide bar I57 in engagement with the notch provided in the ratchet wheel H6 carried by the tubular member I I3 in order positively to prevent rotation of the tubular member H3 with the operating shaft I05. Accordingly, at this time, the spiral groove H2 cut in the outer surface of the enlarged section III of the operating shaft I35 acts upon the pin H4 carried by the tubular member II3, thereby to cause the pin I I4 to ride in the spiral groove H2. As the pin II l carried by the tubular member H3 rides in the spiral groove H2 cut in the outer surface of the enlarged section II I of the operating shaft I35, the tubular member H3 is slid longitudinally along the enlarged section I I I from the left toward the right, as viewed in Fig. 3. As the tubular member H3 is slid from the left toward the right, as viewed in Fig. 3, th notch provided in the ratchet wheel H6 carried thereby slides in engagement with the guide bar I51, thereby positively to prevent rotation of the tubular member ,I I3 and continues sliding thereof along the enlarged section III of the operating shaft I05.

As the tubular member I I3 is slid longitudinally along the outer surface of the enlarged section III of the operating shaft I35 from the left toward the right, as viewed in Fig. 3, the carriage I06 is moved therewith due to the fact that the walls adjacent the semicircular recess I provided in the upper portion thereof straddle the annular groove H8 provided in the outer surface of the tubular member H3. Accordingly, the carriage I03 is slid longitudinally with the tubular member H3 from the left toward the right, as viewed in Fig. 3, the tubular members I09 and III] secured to the opposite sides of the carriage I06 respectively sliding along the guide bars I01 and I08. As the carriage IE6 is slid longitudinally from the left toward the right, as

viewed in Fig. 3, the sprocket wheels I and I26 are slid therewith along the guide bars I01 and I08, respectively, and the slide I21 is moved therewith. When the slide I21 is moved from the left toward the right, as viewed in Fig. 3, the spaced-apart guide members I31 of the wiper set 'IIlA carried thereby receive the guide strip I46 of the selected row of contact sets therebetween, thereby positively to guide the wiper set IDA in its sliding movement with respect to the associated row of contact sets. As the wiper set IDA is thus moved from the left toward the right, as viewed in Fig. 3, it progressively engages the individual contact sets in the previously selected row of contact sets. As previously noted, the line wipers of the wiper set IIIA successively engage and disengage the line contacts in the associated contact sets; while the control wiper bridges the control contacts in the associated sets that, at the conclusion of agiven unit time interval, the wiper set I 3A engages the first contact set in the previously selected row of contact sets, and, at the conclusion of any number of unit time intervals between I and II, the wiper set IIlA engages a corresponding individual contact set in the previously selected row of contact sets. Thus, at the conclusion of the first, second, etc., and eleventh unit time intervals the wiper set IIlA engages the corresponding first, second, etc., and eleventh individual contact sets in the previously selected row of contact sets.

At the conclusion of the given time interval the winding I 69 of the go magnet A is deenergized and the winding III of the stop magnet QiiA is energized, as previously noted, whereupon the field element I72 of the stop magnet 93A attracts the annular flange I68, thereby to lock the spiral leaf spring I32 against unwinding and the consequent rotation of the operating shaft I05 in a counterclockwise direction, as viewed in Fig. 2.

At this time, the wiper set I EA has selected a particular row of contact sets, corresponding to the first time interval mentioned, and a particular contact set in the selected row of contact sets, corresponding to the second time interval mentioned, thereby to establish a connection between the wiper set IiiA and the last-mentioned contact set. The switch IE9 is retained in its operated position as long as the winding ill of the stop magnet 33A is retained energized, thereby to prevent unwinding of the helical leaf spring I62, in an obvious manner.

It is noted that during the first motion of the switch I30, when the slide I2? is moved laterally from its normal position at the right toward the left, as viewed in Fig. 2, the first motion normal switch 36A is operated. In the event that the slide I 2? is moved laterally from the right toward the left, as viewed in Fig. 2, to a position disposed in longitudinal alignment w th the eleventh row of contact sets, the first motion limit switch 59A is operated. Similarly, during the second motion of the switch I00, when the carriage IE6 is moved longitudinally from its normal position at the left toward the right. as viewed in Fig. 3, the second motion normal switch 63A is operated. In the event that the carriage IE6 is moved longitudinally from the left toward the right, as viewed in Fig. 3, into engagement with the eleventh contact set in the previously selected row of contact sets, the second motion limit switch 16A is operated.

In order completely to release the switch I00 after it has been fully operated in the manner previously explained, it is only necessary to deenergize the winding llI of the stop magnet 33A, whereupon the annular flange I 68 is unlocked with respect to the field element I12, thereby to permit unwinding of the spiral leaf spring I62 and the consequent rotation of the operating shaft 35 in a counterclockwise direction, as viewed in Fig. 2. At this time the winding I5I of the shift magnet 36A is retained energized, thereby to retain the armature I49 thereof in its operated position. The operated armature I49 retains the guide bar I51 in he associated notch provided in the ratchet wheel H 3 carried by the tubular member H3, in the manner previously explained. Accordingly, as the operating shaft I35 is rotated in a counterclockwise direction, as viewed in Fig. 2, the tubular member I I3 is slid longitudinally along the outer surface of the enlarged section III of the operating shaft 35 from the right toward the left, as viewed in Fig. 3, due to the cooperation between the pin I 54 carried by the tubular memher I I3 and the associated engaged spiral groove Il2 cut in the outer surface of the enlarged section III of the operating shaft H55, in the manner previously explained.

When the tubular member H3 is returned to its normal position and, consequently, the carriage Ids to its normal position at the left, as viewed in Fig. 3, the winding IbI of the shift magnet 39A is deenergized, whereupon the armature M9 is released and rotated in a counterclockwise direction about the pivot pin I58, as viewed in Fig. 2, by the coil spring I54. When the armature his is thus restored the finger I55 carried thereby is returned into the annular groove H9 disposed in the outer surface of the tubular member I I3, thereby to lock the tubular member I53 against longitudinal sliding on the outer surface of the enlarged section III of the operating shaft m5 incident to the next cycle of operation of the switch Illt Also, when the armature M9 is thus released the outer end of the guide bar its! is lowered out of engagement with the associated notch in the ratchet wheel Hit, thereby to unlock the tubular member M3 for rotation, in a counterclockwise direction. with the operating shaft I55. The spiral leaf spr ng :52 then rotates the operating shaft E85 and the tubular member 5 i3 in a counterclockwise dire-ction, as viewed in Fig. 2, whereupon the endless chain ISQ is rotated in a counterclockwise direction, in order to restore the slide I21 to its normal position at the right, as viewed in Fig, 2.

When the carriage I65 is returned to its normal position at the left, as viewed in Fig. 3, the second motion normal switch 6 3A is operated; and when the slide I2? is moved to its normal position at the right, as viewed in Fig. 2, the first motion normal switch 455A is operated. Of course, the second motion limit switch ItA is operated when the carriage tilt is moved from its final right position, as viewed in Fig. 3, in the event that the carriage I 35 was so moved as to operate the second motion limit switch 35A initially; similarly, the first motion limit switch fi lA is operated when the slide I2? is moved from its final left position, as viewed in Fig. 2, in the event that the slide I2! was so moved as to operate the first motion limit switch 55A initially. Also, when the armature I49 of the shift magnet 38A is released the set of switch springs 35A is operated in an obvious manner. At this time, the switch I60 is completely released and available for further use.

Construction and operation of the modified form of the automatic switch Referring now more particularly to Figs. 4 and 5 of the drawings there is illustrated a modified form of an automatic switch 439 embodying the present invention, which comprises a support 4M including side walls 4M and 4&3, a rear wall 43 a bottom wall 495, and an operating shaft 456. The operating shaft 4&6 is substantially centrally disposed between the side walls 462 and 4 53 of the support 4%, the lower end of the operating shaft 456 being suitably journaled in a step bearing 46! suitably fixed to the bottom wall G85 of the support 481. The upper end of the operating shaft 486 is suitably journaled in a bearing collar 488 which in turn is suitably fixed in an opening provided in a transverse angle plate 409 extending between and suitably secured to the side walls 492 and 493 of the support 49f. Also, the switch 4% comprises a rotatable and longitudinally slidable carriage 419 including a cylindrical side wall 4! I, an annular bottom wall M2 and an annular top wall 4H3 suitably secured together to provide a rigid construction. The carriage 4H3 surrounds the operating shaft 4&6 and is adapted for longitudinal sliding movement thereon, the operating shaft 435 extending through aligned slide bearings respectively provided in the annular bottom wall H2 and the annular top wall 4I3. The carriage llfi is operatively connected to the operating shaft 485 by an arrangement comprising a pin 4M secured to the operating shaft 333 and a semi-spiral or helical groove 4I5 out in the outer surface of the cylindrical side wall 4| I, the pin 4M projecting into the spiral groove 4I5.

Further, the switch 4E0 comprises a contact controlling member ISB in the form of a wiper set which is carried by the top wall H3 of the carriage 4H3. At this point it is noted that the control wiper of the wiper set IQB is of the bridging type; while the line wipers thereof are not of the bridging type, this arrangement being utilized for a purpose more fully explained hereinafter. The individual wipers of the wiper set IilB- are suitably secured together and to the top wall MS of the carriage 4H) and are suitably insulated from each other and from the top wall 453 by interposed strips of insulation, not shown. Also, the switch 40!] comprises a unitary contact bank 4E5, including a semi-cylindrical supporting plate 4I'I suitably secured to the side walls G32 and 403 of the support 4M and eleven circumferentially spaced-apart and longitudinally extending rows of contact sets, the first row of contact sets being indicated at 458. Each row of contact sets comprises eleven individual contact sets, the first contact set in the first rows of contact sets 4I8 being indicated at 233. The individual row of contact sets are suitably secured in radially disposed openings 419 provided in the semi-cylindrical supporting plate 4H. Also, the individual contacts in each contact set in each row of contact sets are insulated from each other by a plurality of longitudinally extending interposed strips of insulation 428 and 52!, the insulating strip 42I being centrally disposed with respect to the row of contact sets and constituting a guide strip. At this point it is noted that the individual wipers in the wiper set IfiB are arranged in pairs; and the individual contacts in each contact set in each row of contact sets are arranged in pairs; whereby each pair of wipers in the wiper set IfiB is adapted to shunt or connect together a corresponding pair of individual contacts in each contact set in each row of contact sets.

Further, the switch 421] comprises an arrangement including a shift magnet 30B for controlling the rotary and longitudinal movements of the carriage 4H]. The shift magnet 35B comprises a core 422, a field element 423 and a movable armature 424, the armature 424 being pivotally mounted on the outer end of the field element 423 by a pivot pin 425. Also, the core 422 carries an operating winding 425 and a copper sleeve 42?, the copper sleeve 42? rendering the armature 224 slow to release after the operating winding 426 has been deenergized. The core 422 and the field element 423 are suitably secured to a bracket 428 which in turn is suitably fixed to the side wall 443 of the support 40!. Further, the field element 423 carries a set of switch springs 353 which is operatively associated with the armature 424, thereby to bias the armature 424 in a counterclockwise direction about the pivot pin 425, as viewed in Fig. 5. Finally, the armature 424 carries an operating arm 429, the outer end of which is disposed below the bottom wall 4|2 of the carriage 4H1. At this point it is noted that the armature 424 is adapted to be rotated in a clockwise direction about the pivot pin 425, as viewed in Fig. 5, thereby to cause the operating arm 429 thereof to lift or slide the carriage 4|!) longitudinally of the operating shaft 405. Finally, in this connection, it is noted that the upper end of the spiral groove 4|5 cut in the outer surface of the cylindrical side wall 4!! of the carriage 4lil terminates in a substantially straight portion 430 which is normally disposed in engagement with the pin 4!4 carried by the operating shaft 445. Accordingly, it will be understood that when the carriage 4H3 is lifted or slid longitudinally of the operating shaft 456 the pin 4!4 carried by the operating shaft 406 rides out of the straight portion 435 of the spiral groove 4! into the spiral or helical portion thereof, in an obvious manner.

Further, the switch 450 comprises four sets of switch springs 45B, 55B, 60B and TUB, the individual switch springs in the set of switch springs 45B being suitably secured to a transverse bracket 43! extending between and suitably fixed tothe side walls 442 and 453 of the support 44! and insulated from each other, and the individual switch springs in the set of switch springs 54B being suitably secured to the bracket 43! and insulated from each other. Also, the individual switch springs in the set of switch springs 60B are suitably secured to the bracket 43! and insulated from'each other. Finally, the individual switch springs in the set of switch springs WE are suitably secured to the plate 449 and insulated from each other. The set of switch springs 45B constitutes a first motion normal switch cooperating with a projection 433 fixed to the outer surface of the cylindrical side wall 4!! of the carriage 4H); while the set of switch springs 58B constitutes a first motion limit switch cooperating with the projection 433. The set of switch Springs 643 constitutes a second motion normal switch cooperating with the top wall 4!3 of the carriage 4H3; while the set of switch springs B constitutes a second motion limit switch cooperating with the top wall Further, the switch45fl comprises a driving arrangement including a go magnet 84B, a stop magnet 943, a spiral leaf spring 434 and a drive shaft !5B. The spiral leaf; spring is wound around the operating shaft 445, one end of the leaf spring 434 being secured to the operating shaft 405 and the other end of the leaf spring 434 being secured to a stud 435 anchored to the bottom wall 405 of the support 44!. The upper end of the operating shaft 446 carries a tubular collar 435 slidably mounted thereon, a pin 43! being fixed to the operating shaft 446 and arranged in a longitudinally extending slot 438 formed in the tubular collar 436. The lower end of the tubular collar 436 is normally supported upon the bearing collar 408. The outer end of the tubular collar 435 carries an annular flange 445 formed of magnetic material. The go magnet BUB comprises an operating winding 44! and a magnetic field element 442, the field element 442 being arranged in operative relation with respect to the annular flange 445. Similarly, the stop magnet 953 comprises an operating winding 443 and a magnetic field element 444, the field element 444 being arranged in operative relation with respect to the annular flange 4-45. The go magnet 84B is supported by a bracket 445 suitably secured to a transverse angle plate 445 extending between and suitably fixed to the side walls 452 and 453 of the support 45! while the stop magnet 55B is supported by a bracket 44! suitably secured to the plate 459. Further, a stub shaft 445 is suitably journaled in a substantially U-shaped bracket 449 which in turn is suitably fixed to the plate 445. The inner end of the stub shaft 448 carries an annular drive plate 455 formed of resilient material, such as rubber, leather or the like, which cooperates with the annular flange 444. The outer end of the stub shaft 448 carries a bevel gear 45! arranged in driven relation with respect to an associated bevel gear 452 carried by the drive shaft I5B. It is noted that the drive shaft !5B is common to a plurality of switches of the character of the switch 444 and is suitably journaled in an external support, not shown, Preferably, the drive shaft !5B is driven in a clockwise direction, as viewed in Fig. 5, by a constant speed motor, not shown, such as a synchronous motor, whereby the speed of rotation of the drive shaft I5B is maintained within extremely close limits. It is noted that the bevel gear 45! is arranged in constant meshing relation with the bevel gear 452, whereby the stub shaft 448 is constantly driven in a clockwise direction, as viewed in Fig. 4, by the drive shaft !5B.

Further, the switch 45!] comprises a release arrangement including a release magnet 85B and a ratchet wheel 453, the ratchet wheel 453 being fixed to the operating shaft 455. The release magnet 85B comprises a core 454, a field element 455 suitably secured to the bottom Wall 445 of the support 451i, and an armature 456, the armature 455 being pivotally mounted on the outer end of the field element 455 by a pivot pin 451. The core 454 carries an operating winding 458 and a copper sleeve 459, the copper sleeve rendering the armature 455 slow to operate after the operating winding 458 is energized. The armature 456 is biased in a clockwise direction about the pivot pin 45?, as viewed in Fig. 4, by an arrangement comprising a set of switch springs B suitably secured to the field element 455, the individual switch springs in the set of switch springs 9513 being suitably insulated from each other and from the field element 455 by interposed strips of insulation 455. The outer end of the armature 455 carries a pawl 45! operatively associated with the ratchet wheel 453, whereby the ratchet Wheel 453 may be freely rotated in a clockwise direction, as viewed in Fig. 4, when the armature 45B is released, but may be rotated in the counterclockwise direction, as viewed in Fig. 4, only when the armature 455 is operated.

At this point it is noted that the switch 434 as a whole is supported in cooperating relation with the drive shaft I513 upon an external support, not shown, whereby the bevel gear 45! is arranged in meshing relation with the bevel gear 452, as previously noted. Also, the switch 440 may be removed as a whole from its external support relative to the drive shaft I5B, thereby to facilitate replacement or repair thereof.

When the switch 443 is completely released the winding 44! of the go magnet 8GB and the winding 443 of the stop magnet 99B are deenergized; the operating shaft 495 is biased in a counterclockwise direction, as viewed in Fig. 4, by the spiral leaf spring 434; and the stub shaft 448 is driven at a constant speed in the clockwise direction, as viewed in Fig. 4, by the constantly rotating drive shaft ISB. When the switch 405 is thus completely released the tubular collar 436 occupies its retracted position toward the bottom, as viewed in Fig. 5, whereby the annular flange 44%) completely disengages the annular drive plate 45%. Also, at this time, the carriage 4H] occupies its completely retracted position in a counterclockwise direction, as viewed in Fig. 4, with respect to the contact bank 4 5, and its completely retracted position toward the bottom, as viewed in Fig. 5, with respect to the contact bank 4H5.

In order to operate the switch 4%, thereby to cause the wiper set ltB to select a particular group or row of contact sets, the winding 44! of the go magnet 35B is first energized and retained energized for a corresponding given time interval, depending upon the speed of operation of the switch 489 relative to the speed of rotation of the stub shaft 448, this given time interval comprising one or more unit time intervals, as explained more fully hereinafter; at the conclusion of this given time interval the winding 44! of the go magnet 85B is deenergized and the winding 443 of the stop magnet BUB is energized. When the winding 44! of the go magnet 83B is thus energized the field element 442 thereof attracts the annular flange 44-6, thereby to cause the annular flange 444 to move toward the top, as viewed in 5, into frictional engagement with the annular drive plate 45%, the pin and slot connection 'elififi between the operating shaft 436 and the tubular collar 435 accommodating this movement of the tubular collar 436 and the annular flange 44% carried thereby. When the annular flange 44b is thus moved by the go magnet 853 into frictional engagement with the annular drive plate 453 the operating shaft 4% is rotated a clockwise direction, as viewed in Fig. 4, with the stub shaft 448, thereby to cause the spiral leaf spring 434 to be wound up.

At this time, the winding 425 of the shift magnet 38B is deenergized, whereby the armature 424 occupies its normal position, being biased in a counterclockwise direction about the pivot pin 425, as viewed in Fig. 5, by the set of switch springs 35B. Accordingly, the carriage 4m occupies its retracted position toward the bottom, as viewed in Fig. 5, whereby the pin 4|4 carried by the operating shaft 4535 engages the straight portion 43!] of the spiral groove 4H5 cut in the cylindrical side wall 4!! of the carriage 418.

As the operating shaft 465 is rotated in a clockwise direction, as viewed in Fig. 4 at this time, the pin 448 carried by the operating shaft 4G6 acts upon the straight portion 439 of the spiral groove 4E5 cut in the cylindrical side wall 4 of the carriage 4H3, thereby to lock the carriage 4!!! to the operating shaft 466 for rotation therewith. Accordingly, the carriage are is rotated with the operating shaft 438, thereby to cause the wiper set IGB to be rotated below the lower ends of the various rows of contact sets without engagement therewith, whereby the wiper set Isl-3 is moved progressively to select the various rows of contact sets in a continuous motion and at a uniform speed. The speed of rotation of the operating shaft 466 is so proportioned relative to the circumferential spacing between the rows of contact sets that, at the conclusion of a given unit time interval, the wiper set HEB occupies a position in longitudinal alignment with respect to the first row of contact sets M8; and at the conclusion of any number of time intervals between I and II the wiper set 1GB occupies a position in longitudinal alignment with respect to a corresponding row of contact sets. Thus, at the conclusion of the first, second, etc., and eleventh unit time intervals, the wiper set [EB occupies positions respectively disposed in longitudinal alignment with respect to the corresponding first, second, etc., and eleventh rows of contact sets.

At the conclusion of the given time interval the winding 44! of the go magnet 83B is deenergized and the winding 443 of the stop magnet B is energized, as previously noted, whereupon the field element 444 of the stop magnet 90B attracts the annular flange 440, causing the tubular collar 436 and the annular flange 440 carried thereby to be moved toward the bottom, as viewed in Fig. 5, the pin and slot connection 431-438 between the operating shaft 406 and the tubular collar 436 facilitating this movement. At this time, the winding 443 of the stop magnet 90B is retained energized, thereby to retain the annular flange 440 out of engagement with the annular drive plate 450 and in locked engagement with the field element 444. As long as the winding 443 of the stop magnet 90B is retained energized, the annular flange 44B is retained in locked engagement with respect to the field element 444, thereby to retain the spiral leaf spring 434 in its wound condition and to prevent unwinding thereof and the consequent rotation of the operating shaft 406 in a counterclockwise direction, as viewed in Fig. 4, in a manner more fully explained hereinafter. Also, at this time, the winding 458 of the release magnet 85B is deenergized, whereby the armature 456 occupies its released position, being biased in a clockwise direction about the pivot pin 451, as viewed in Fig. 4, by the set of switch springs B. Thus, the pawl 48! carried by the armature 45% engages one of the notches provided in the ratchet wheel 453, thereby positively to retain the spiral leaf spring 434 in its wound condition and positively to prevent unwinding thereof and the consequent rotation of the operating shaft 456 in a counterclockwise direction, as viewed in Fig. 2.

At the conclusion of the rotary movement of the carriage H6 in a clockwise direction, as viewed in Fig. 4, which motion constitutes the first motion of the switch 489, the winding 426 of the shift magnet 30B is energized. When the winding 426 of the shift magnet 30B is thus energized the armature 424 is attracted and rotated in a clockwise direction about the pivot pin 425, as viewed in Fig. 5, against the bias of the set of switch springs 353. When the armature 424 is thus operated the arm 429 carried thereby is forced against the bottom wall 412 of the carriage 4H) and exerts a lifting action thereon, whereby the carriage M9 is lifted or slid longitudinally toward the top, as viewed in Fig. 5, thereby to disengage the pin 4M carried by the operating shaft 466 and t. e straight portion 435] of the spiral groove 445 out in the cylindrical side wall 4 of the carriage 4H], and to engage the pin 454 and the helical portion of the spiral groove 4E5 cut in the cylindrical side wall 4| I. Also, when the carriage m is thus lifted or moved longitudinally toward the top, as viewed in Fig. 5, the guide strip 42! of the previously selected row of contact sets is forced between the individual wipers of the wiper set [B, thereby positively to lock the wiper set IGB and the carriage 4H] against further rotation in the clockwise direction, as viewed in Fig. 4. At this time, the carriage fililis adapted for longitudinal sliding movement toward the top, as viewed in Fig. 5, along the operating shaft 506.

At this point, it is noted that the winding 425 of the shift magnet 30B is energized substantially simultaneously with the deenergization of the winding Mil of the go magnet 86B and the energization of the winding 443 of the stop magnet 903. During the brief interval of time between the deenergization of the winding Ml of the go magnet 86B and the effective energization of the winding 443 of the stop magnet 953, the spiral leaf spring @3 1 tends to unwind, thereby to rotate the operating shaft 406 in, a counterclockwise direction, as viewed in Fig. 4. However, the spiral leaf spring 83G is preventedfrom effective unwinding; and the position of the operating shaft W6 and, consequently, the carriage M0 and the wiper set IGB carried thereby is precisely centered by the action of the pawl 46! carried by the armature 456. This arrangement not only positively prevents effective unwinding of the spiral leaf spring 434, as previously explained, but it also positively insures that the wiper IUB occupies a position in precise longitudinal alignment with respect to the selected row of contact sets when the winding 428 of the shift magnet 30B is efiectively energized and the armature 424 is operated, thereby insuring that the guide strip MI is received in proper alignment between the individual wipers of the wiper set IOB.

. Also, when the armature 424 of the shift ma net 3913 is thus operated the set of switch springs 35B is operated, for a purpose more fully explained hereinafter.

After the switch @053 has been operated in the manner described above, thereby to select one of the rows of contact sets, in order further to operate the switch Mill to select a particular contact set in the previously selected row of contact sets, the winding 463 of the stop magnet 9GB is first deenergized and the winding Mi of the go magnet MB is energized for a corresponding given time interval depending upon the speed of operation of the switch 100 relative to the speed of rotation of the stub shaft 4G3, this given time interval comprising one or more unit time intervals, as previously explained. At the conclusion of this given time interval the winding 44! of the g0 magnet 88B is deenergized and the winding 3 of the stop magnet QfiB is energized. When the winding M3 of the stop magnet 91B is thus deenergized the field element 444 releases the annular flange M0; and when the winding id! of the go magnet 80B is thus energized the field element 442 attracts the annular flange Mil, thereby to clutch the annular flange M0 to the annular drive plate 455, in the manner previously explained; whereby the operating shaft 466 is again rotated in the clockwise direction, as viewed in Fig. 4, with the stub shaft 448, thereby to cause the spiral leaf spring 534 to be further wound up.

At this time the winding 426 of the shift magnet 3GB is energized and the armature 524 cccupies its operated position, thereby to retain the carriage M in its lifted position, as viewed in Fig. 5. Accordingly, at this time, the helical portion of the spiral groove 4H5 cut in the cylin:

drical side wall 4H of the carriage 4H operatively engages the pin M4 carried by the operating shaft 4-36, thereby to cause the pin M4 to ride in the spiral groove H5. As the pin M4 carried by the operating shaft 366 rides in the spiral groove H5 cut in the cylindrical side wall 4H of the carriage M0, the carriage M0 is lifted or slid longitudinally toward the top, as viewed in Fig. 5, along the operating shaft 6%. As the carriage H9 is slid longitudinally toward the top, as viewed in Fig. 5, the guide strip A2! of the previously selected row of contact sets is disposed between the individual wipers of the wiper set HEB carried by the carriage Ml], thereby positively to prevent rotation of the carriage MG and to insure continuous longitudinal sliding of the carriage M0 and the wiper set IQB carried thereby toward the top, as viewed in Fig. 5.

As the wiper set 163 is thus moved longitudinally toward the top, as viewed in Fig. 5, it progressively engages the individual contact sets in the previously selected row of contact sets. As previously noted, the line wipers of the wiper set EBB successively engage and dis engage the line contacts in the associated contact sets; while the control wiper thereof bridges the control contacts in the associated contact sets for a purpose more fully explained hereinafter.

The speed of rotation of the operating shaft 406 is so proportioned relative to the pitch of the spiral groove M5 cut in the cylindrical side wall ill of the carriage ift] and the longitudinal spacing between the individual contact sets in the row of contact sets that at the conclusion of a given unit time interval the wiper set 10B engages the first contact set in the previously selected row of contact sets, and at the conclusion of any number of unit time intervals between I and H, the wiper set IGB engages a corresponding individual contact set in the previously selected row of contact sets. Thus at the conclusion of the first, second, etc., and eleventh unit time intervals the wiper set EBB engages the corresponding first, second, etc., and eleventh individual contact sets in the previously selected row of contact sets.

At the conclusion of the given time interval the winding .4! of the go magnet B is deenergized and the winding 443 of the stop magnet 91313 is energized as previously noted, whereupon the field element M4 of the stop magnet 9GB attracts the annular flange Mill, thereby to lock the spiral leaf spring 334 against unwinding and the consequent rotation of the operating shaft 496 in a counterclockwise direction, as viewed in Fig. 4. During the brief interval of time between the deenergization of the winding MI of the go magnet MB and the effective energization of the winding 443 of the stop magnet SUB the spiral leaf spring 434 tends to unwind, thereby to rotate the operating shaft 406 in a counterclockwise direction, as viewed in Fig. 4. However, the spiral leaf spring 434 is prevented from effective unwinding; and the position of the operating shaft 406 and, consequently. the longitudinal position of the carriage 4m and the wiper set IEiB carried thereby is precisely centered by the action of the pawl iBl' carried by the armature 456 of the release magnet B. This arrangement not only positively prevents effective unwinding of the spiral leaf spring 434, as previously explained, but it also positively insures that the wiper set [0B occupies a position in centered engagement with respect to the selected contact set in the previously selected row of contact sets.

At this time the Wiper set IEB has selected a particular row of contact sets, corresponding to the first time interval mentioned, and a particular contact set in the selected row of contact sets, corresponding to the second time interval mentioned, thereby to establish a shunt connection between the pairs of individual contacts in the selected contact set. The switch 4% is retained in its operated position so long as the winding of the stop magnet 95B is retained energized, and the winding 458 of the release magnet 85B is retained deenergized, thereby to prevent unwinding of the spiral leaf spring 456 in an obvious manner.

It is noted that du ing the first motion of the switch 4% when the carriage did is rotated in a clockwise direction from its normal position at the left toward the right, as viewed in Fig. 4, the first motion normal switch 4GB is operated by the projection 433 carried by the cylindrical side wall (it! of the carriage 419. In the event that the carriage dill is rotated in a clockwise direction, as viewed in Fig. 4, to a position disposed in longitudinal alignment with the ele enth row of contact sets, the first motion limit switch 5S3 is operated by the projection carried by the cylindrical side wall lil of the carriage ilo. Similarly, during the second motion of the switch 4% when the carriage sac is slid longitudinally from its normal position at the bottom toward the top, as viewed in Fig. 5, the second motion normal switch E iB is operated by the top wall MS of the carriage In the event that the carriage M6 is moved longitudinally toward the top, as viewed in Fig. 5,

into engagement with the eleventh contact set in the previously selected row of contact sets, the second motion limit switch MB is operated by the top wall .53 of the carriage 4 i ii.

In order completely to release the switch :89 after it has been fully operated in the manner previously explained, it is necessary not only to deenergize the winding 453 of the stop magnet 9523 but also to energize the winding 158 of the release magnet 853. When the stop magnet BBB is thus released the operating shaft 493 is rendered free to rotate in the counterclockwise direction, as viewed in Fig. 4, except for the engagem nt between the pawl 46! and the associated notch provided in the ratchet wheel 453. When the winding 455 of the release magnet 853 is thus energized the armature 755 is operated, thereby to operate the associated set of switch springs and to cause the armature 45a to be rotated in counterclockwise di rection about the pivot pin 351, as viewed in Fig. 4, whereupon the pawl 45d disengages the associated notch in the ratchet wheel 45%. At this time the operating shaft 4% is free to rotate in a counterclockwise direction, as viewed in Fig. 4, and is so rotated by the spiral leaf spring ist incident to the unwinding thereof. Accordingly, as the operating shaft 496 is rotated ir; a counterclockwise direction, as viewed in Fig. 4, the carriage m is slid longitudinally along the operating shaft from the top toward the bottom, as viewed in Fig. 5, due to the cooperation between the pin H4 carried by the operating shaft 4:35 and the spiral groove M5 cut in the cylindri al side wall All of the carriage ll), in the manner previously explained.

When the carriage All) is returned almost to its normal position at the bottom, as viewed in Fig. 5, the winding 423 of the shaft magnet 36B is deenergized, whereupon the armature 429 is released in order to permit the carriage M5 to be moved into its normal position. When the carriage dill is moved into its normal position at the bottom, as viewed in Fig. 5, the guide strip 42 of the previously selected row of switching springs is removed from between the individual wipers of the wiper set 1GB, thereby to unlock the carriage did for rotation in a counterclockwise direction, as viewed in Fig. 4. Also, when the carriage MS is returned to its normal position at the bottom, as viewed in Fig. 5, the pin 4M carried by the operating shaft 6% disengages the helical portion of the spiral groove cut in the cylindrical side wall 4H of the carriage 42c and reengages the straight portion of the spiral groove 4E5, thereby to lock the carriage illi against longitudinal sliding movement on the operating shaft incident to the next cycle of operation of the switch 455 At this time the spiral leaf spring continues to rotate the operating shaft in a counterclockwise direction, as viewed in Fig. 4, whereby the carriage ilii is returned to its normal position at the left, as viewed in Fig. 4.

When the carriage All! is returned to its norposition at the bottom, as viewed in Fig. 5, the second motion normal switch is operated; and when the carriage dill is rotated to its normal position at the left, as viewed in Fig. 4, the first motion normal switch 453B is operated. Of course, the second motion limit switch is operated when the carriage dill is moved from its final top position, as viewed in Fig. 5, in the event that the carriage 485 was so moved as to operate the second motion limit switch initially; similarly, the first motion limit switch 5E3 is operated when the carriage H3 is moved from its final position at the right, as viewed in Fig. 4, in the event that the carriage fill] was so moved as to operate the first motion limit switch 55B initially. Also, when the armature 424 of the shift magnet 35B is released the set of switch springs 35B is operated in an obvious manner.

Finally, when the carriage 4 l 0 is returned both to its normal position at the bottom, as viewed in Fig. 5, and to its normal position at the left, as viewed in Fig. 4, the winding 45% of the release magnet B is deenergized, thereby to release the armature 45-5, whereupon the armature i rotated in a clockwise direction about the pivot pin 65?, as viewed in Fig. 4. At this time the set of switch springs 5-58 is again operated and the pawl 48% carried by the armature 456 reengages one of the notches provided in the ratchet wheel carried by the operating shaft whereupon the operating shaft .65 is again locked against rotation in a counterclockwise direction, as viewed in Fig. 4. At this time the switch 443% is completely released and available for further use.

Connection and arrangement of the telephone system- Referring now more particularly to Figs. 6 and 7 of the drawings, there is illustrated an automatic telephone system comprising an exchange having a plurality of subs riber lines extending thereto, including the subscriber lines Gill and lill respectively extending to the subscriber substations TI and T2. Also the eX- change comprises subscriber controlled switching apparatus for setting up connections between various subscriber lines, this switching apparatus comprising a line switch individual to each subscriber line, the line switches 002 and 102 being individual to the subscriber lines Bill and 10!, respectively, a group of selectors, including the selector 600, and a plurality of groups of connectors, one group of connectors including the connector 100. The number of selectors in the group of selectors and the number of connectors in each group of connectors in the system are determined in accordance with the maximum volume of trafiic the exchange is required to handle. Preferably, each of the line switches has access to each of the selectors; each of the selectors has access to each of the connectors; and each of the connectors has access to each of the subscriber lines in an associated group.

Preferably, each subscriber substation comprises substation apparatus identical to that illustrated at the subscriber substations Ti and T2; the subscriber substation apparatus at the subscriber substation Tl including a transmitter 003, a receiver 600, a hook switch 605 and a calling device 606; and the subscriber substation apparatus at the subscriber substation T2 includes a transmitter 103, a receiver 104, a hook switch 105 and a calling device 100. Preferably, the subscriber substation apparatus at each subscriber substation is entirely conventional with the exception of the calling device, while each calling device embodies the unique construction and arrangement disclosed in Bernard D. Willis Patent No. 2,222,131, granted November 19, 1940. As disclosed in the Willis patent, this calling device is so constructed and arranged that it transmits a single impulse of variable length of time duration, as contrasted with conventional calling devices which transmit a variable series of impulses, this calling device including a finger dial and having the same general external appearance of a conventional calling device.

Preferably, each line switch is identical to the line switches 602 and 102, which line switches are connected and arranged in accordance with conventional practice.

Preferably, each of the selectors is identical to the selector 600 which comprises either an automatic switch of the character of the automatic switch 30, shown in Figs. 1 to 3, inclusive, or an automatic switch of the character ,of the automatic switch 400, shown in Figs, 4 and 5. This automatic switch comprises a go magnet 80X, a stop magnet 90X, a shift magnet 30X, a wiper set 10X, a first motion normal switch 40X, a first motion limit switch 50X, a second motion normal switch X, a second motion limit switch X and a set of switch springs 05X, these elements corresponding in function to the corresponding common elements previously described in the automatic switches I00 and 400, corresponding reference characters being employed. Also, it is noted that in the event that the automatic switch 400 is embodied in the selector 600 that a release magnet 85X and an associated set of switch springs 95X are provided, these elements corresponding in function to the corresponding elements previously described in the automatic switch 400, corresponding reference characters being employed. Further, the selector 600 comprises a group of relays including a line relay R6l0, a hold relay R620, a switch relay R530, and two control relays R040 and R650, and a control network.

Preferably, each of the connectors is identical to the connector 100 which comprises either an automatic switch of the character of the automatic switch I00, shown in Figs. 1 to 3, inclusive, or an automatic switch of the character of the automatic switch 400, shown in Figs. 4 and 5. This automatic switch comprises a go magnet Y, a stop magnet Y, a shift magnet 30Y, a wiper set NY, a first motion normal switch i0Y, a first motion limit switch 50Y, a second motion normal switch 60Y, a second motion limit switch 10Y, and a set of switch springs Y, these elements corresponding in function to the corresponding common elements previously described in the automatic switches I00 and 000, corresponding reference characters being employed. Also, it is noted that in the event the automatic switch 400 is embodied in the connector that a release magnet 85Y and an associated set of switch springs 05Y are provided, these elements corresponding in function to the corresponding elements previously described in the automatic switch 400, corresponding reference characters being employed. Further, the connector 100. comprises a group of relays including a line relay R110, a hold relay R120, a test relay R130, an answer relay R140, a switch relay R150, a ring relay R100, and two control relays R and R180, and a control network.

The connection and arrangement of the automatic telephone system described above are disclosed and claimed in the previously mentioned copending application of Bernard D. Willis.

Operation of the apparatus incorporated in the system The mechanical construction and arrangement of the auto-matic switch I00, shown in Figs. 1 to 3, inclusive, and the automatic switch 400, shown in Figs. 4 and 5, as well as the electrical connection and arrangement of the telephone system shown in Figs. 6 and '1, will best be understood from a consideration of the mode of operation of the apparatus incorporated in the system incident to the extension of a telephone connec-' tion from the subscriber substation TI to the subscriber substation T2.

A call is initiated at the subscriber substation TI by removing the receiver 604 of the telephone instrument thereat from its associated switchhock, thereby to cause the hook switch 605 to operate and complete an obvious connection between the line conductors of the subscriber line 509 terminating in the line switch 602. When a connection is completed between the line conductors of the subscriber line 60!, the line switch 002 operates automatically to search for a trunk extending to an idle selector, in accordance with conventional practice. Assuming that the selector 000 is the first idle selector accessible to the line switch 602, the line switch 602 operates to seize the trunk 660 extending thereto, the trunk 65;? being marked as idle by the absence of potential upon the control conductor 663 thereof. When the line switch 602 seizes the trunk 600, further operation thereof is arrested and it operates to switch through, thereby to complete an obvious connection between the subscriber line 60! and the line conductors 066i and C662 of the trunk 060. When this connection is completed an obvious loop circuit is completed between the calling subscriber substation TI and the upper and lower windings of the line relay new in the selector 600 by way of the line switch 002. When thus energized the line relay ROI0 operates to complete, at the contacts 6| l, a circuit for energizing in series the winding of the control relay R549 and the stop magnet 90X, this circuit extending from ground by way of the contacts 65| and El I, the winding of R640 and the stop magnet 95X to battery. Also, it is noted that th winding of the control relay R540 is normally shunted by the contacts 64! and the resistor 645, this arrangement being provided in order positively to insure that the stop magnet BGX is fully energized promptly. When thus energized, the control relay R659 operates to interrupt, at the contacts 6M, the previously mentioned shunt around the winding thereof, whereby an obvious holding circuit substantially identical to that previously traced is completed for energizing in series the winding of the control relay R640 and the stop magnet 99X. When thus energized the stop magnet HilX operates, thereby to insure that the automatic switch incorporated in the selector 6-38 is declutched from the associated drive shaft. Also, upon operating, the lin relay RSI!) completes at the contacts 6H2 an obvious circuit for energizing the winding of the hold relay R6529, thereby to cause.

the latter relay to operate. Upon operating, the hold relay R526 completes, at the contacts 622, an obvious multiple point in the previously mentioned holding circuit for energizing in series the winding of the control relay R540 and the stop magnet QSX. Also, the hold relay R620 completes, at the contacts 62!, an obvious path for applying ground potential to the control conductor 06% of the trunk 6G0, thereby to mark the trunk 553 as busy to the line switches having access thereto Further, when ground potential is applied to the control conductor C553 of the trunk 65%, it is applied by way of the line switch 632 to the control conductor C6il of the subscriber line 65!, thereby to mark the subscriber line till as busy to the connectors having access thereto. At this time an operative connection is completed between the calling subscriber substation TI and the selector 6%, and the selector 663 is in readiness to receive the first digit.

The subscriber at the calling subscriber substation Ti then dials the first digit in the calling device thereat, thereby to cause the previously traced connection between the calling subscriber substation T! and the line relay Rtli] in the selector 6% to be interrupted, to remain interrupted for a corresponding given time interval, and then to be recompleted at the conclusion of the given time interval, the duration of the given time interval being determined by the particular digit dialed in the calling device 6&6 at

the calling subscriber substation Ti, as disclosed in the previously mentioned Willis patent. Accordingly, the line relay R630 restores, remains restored for the given time interval and then reopcrates.

-pletes, at the contacts 653, a circuit for l g in series the winding of the control relay R559 and the go magnet EilX, this circuit extending from ground by way of the contacts did and the contacts 62 of the second motion normal switch the winding of REE-3 and the go magnet to battery. It is noted that the winding of the control relay R653 is normally shunted by the contacts and the resistor 655, this arrangement being provided in order positively to insure that the go magnet 83X is fully enei zed promptly. When thus energized the control relay R5553 operates to interrupt, at the contacts 552, the previously mentioned shunt around the winding thereof, whereby an obvious Upon restoring, the line relay holding circuit substantially identical to that previously traced is completed for energizing in series the winding of the control relay R659 and the go magnet X.

Also, the control relay R550 interrupts, at the contacts 65!, the previously traced holding circuit for energizing in series the winding of the control relay R640 and the stop magnet X, thereby to cause the control relay R640 to restore and the stop magnet 99X to release. When the stop magnet SQX is thus released and the go magnet 83X is thus operated, the automatic switch incorporated in the selector 600 is clutched to the associated drive shaft, whereupon the first motion thereof is initiated in the manner previously explained, whereupon the first motion normal switch idX is operated. When the first motion normal switch 46X is thus operated there is completed, at the contacts 43 thereof, an obvious alternative path for applying ground potential to the control conductor C563 of the trunk 5651, thereby to retain both the trunk 669 and the calling subscriber line 5M marked as busy, as previously explained. Also, at the contacts 32 of the first motion normal switch 49X, there is completed a holding circuit for energizing in series the winding of the control relay R556 and the go magnet 88X, this circuit extending from ground by way of the contacts 613, the contacts 52 of the second motion limit switch TeX, the contacts 42 of the first motion normal switch MEX, the contacts 653, the winding of Rfifiil and the go magnet 88X to battery.

Also, upon restoring, the line relay R5!!! interrupts, at the contacts 6l2, the previously mentioned circuit for energizing the winding of the hold relay R528, thereby to cause the latter relay to restore shortly thereafter, the holding relay R320 being of the slow-to-release type. Upon restoring, the hold relay R520 interrupts, at the contacts 622, a further point in the previously traced holding circuit for energizing in series the winding of the control relay R640 and the stop magnet SllX; interrupts, at the contacts 62!, the previously mentioned original path for applying ground potential to the control conductor C663 of the trunk 660, and interrupts, at the contacts 623, the previously traced original circuit for energizing in series the winding of the control relay R650 and the go magnet 89X.

Accordingly, at this time the wiper set I 8X of the automatic switch incorporated in the selector 690 is being driven continuously in the first motion, in the manner previously explained; and continues to be so driven until the conclusion of the first digit, whereupon the line relay R6! reoperates as previously explained. Upon reoperating, the line relay RGIO interrupts, at the contacts M3, the previously traced holding circuit for energizing in series the winding of the control relay R659 and the g0 magnet 88X, thereby to cause the control relay R559 to restore and the go magnet 86X to release. Upon restoring, the control relay R850 completes, at the contacts 65| the previously traced original circuit for energizing in series the winding of the control relay RBMJ and. the stop magnet 96X, thereby to cause both the control relay R648 and the stop magnet X to reoperate. Upon reoperating, the stop magnet 99X declutches the automatic switch incorporated in the selector 660 from the associated drive shaft, thereby positively to arrest further operation thereof in the first motion, in the manner previously explained. Also, upon reoperating, the line relay RGIU recompletes, at the

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