US2490665A - Automatic telephone switch - Google Patents

Description

Dec. 6, 1949 J. l. BELLAMY AUTOMATIC TELEPHONE SWITCH Filed March 1, 1944 9 26 was" 6 She ets-Sheet 1 Dec. 6, 1949 J. l. BELLAMY 2,490,665

AUTOMATIC TELEPHONE SWITCH Filed March 1, 1944 6 Sheets-Sheet 3 JUL/E2720]? 1949 J. I. BELLAMY 2,490,665

AUTOMATIC TELEPHONE SWITCH Filed March 1. 1944 6 Sheets-Sheet 5 Jain? [BE/Z5277 15;? W

Dec. 6, 1949 Filed March 1, 1944 J. l. BELLAMY AUTOMATIC TELEPHONE SWITCH 6 Sheets-Sheet 6 JaZmZEEi/an? E E1.

127 UE'IYEUJ" I set, whereby the Patented Dec. 6, 1949 UNITED STATES PATENT OFFICE 2.490.665 AUTOMATIC TELEPHONE SWITCH John I. Bellamy, Brookfield, Ill., assignor to Kellogg Switchboard and Supply Company, Chicago, 111., a corporation of Illinois Application March 1, 1944, Serial No. 524,816

20 Claims.

GENERAL DESCRIPTION As disclosed in the above-noted prior application, the switching apparatus under discussion includes similar individual switches arranged in a row, with each switch comprising a number of selectively operable stackups of contact members, and common selecting shafts exstackup therein for operation.

Among the features of the present invention are the following:

1. The selective capacity of each individual switch in a group is doubled by providing an additional stackup, common selecting shaft, which selects one or any selected stackup.

2. The stackups of contact members of a switch (excluding the additional stackup) take the form of a unitary contact bank which is readily attachable to and detachable from the individual switch to which it is assigned. In this bank construction, the parts comprise separate subassembly strips gether in superposed relationship, each such strip carrying a blade member for each of the several stackups provided by the bank, thereby facilitating production and assembly.

3. The contact blades forming the selective stackups of the contact bank have their rearwardly extending terminal portions forwardly extending stackups may be equally spaced to permit adjustment and inspection access from both sides, while the finger structure controlled by an additional adapted to be secured -toactuating portion; an intermediate portion cooperates with a fixed pivot; and the front portion serves as flexible arms controlled by a selecting shaft.

sition by retaining spring clips.

6. The parallel mounting rails on which a group of switches are mounted are permitted to be brought closer together, and the frame structure of the individual switches is simplified, by mounting the switches on the face of the mounting rails, rather than between them as in the prior arrangement.

7. Each of the common selecting shafts takes the form of a length of metal tubing having a finger-controlling web extension formed integrally therewith, a pair of insert members being provided at the ends for pivotally supporting the shaft for rotation.

8. Improved positioning mechanism renders the shafts more readily removable and replaceable, and the normal position of a shaft is readily adjustable, as is the tension of .the shaft-restoring spring.

9. A still further feature relatesto the provision of an improved arrangement. for providing intermediate guide points for long controlling shafts, the construction being such that of a shaft does not need appear hereinafter.

The accompanying drawings, comprising Figs. 1 to 18, show a preferred embodiment of the invention.

Fig. 1 is a front view of a mounting rack on which two or more groups of switches constructed according to the invention are mounted;

Fig. 2 is a left-side view of one of the selecting shafts shown in Fig. 1;

Fig. 3 is a view taken along line 3-3 of Fig. 1 showing a top of the first group of switches;

Fig. 4 is a top view of the first individual switch of the first group, looking down along line 4-4 of Fig. 1;

Fig. 5 is a view similar to Fig. 4 with certain parts removed to permit a clearer view of the frame structure of the individual switch;

Figs. 6 to 9 are side sectional views along lines 6-5 to 9-9 respectively of Fig. 4, looking to the left as indicated by the arrowheads;

Figs. 10 to 14, together with their associated auxiliary views, show parts used in making up the contact bank 60 of an individual swi- ..h;

Fig. 15 show a partially diagrammatic front view of an assembled contact bank;

view of-the upper shaft bracket The invention having been described generally, a detailed description of the disclosure will now be given.

General arrangement Referring particularly to Fig. l, the general arrangement of the improved switching structure will first be described.

As previously noted, Fig. 1 illustrates two or more groups of automatic switches mounted on a vertically disposed mounting rack. The mounting rack, only fragmentarily shown, includes the parallel mounting rails I and 3, secured together at the top by cross member 2.

. The first (uppermost) group of switches includes the switches mounted between the upper shaft bracket 4 and the lower shaft bracket of the group, while the second group of switches includes switches (not shown) mounted below shaft bracket 4, being the upper shaft bracket of the second group, and being exactly similar to the upper shaft bracket 4 of the first group.

The upper shaft bracket of the second group is shown principally to illustrate the relatively small amount of space required between adjacent switch groups on the same mounting rack,

Each of the individual switches mounted between shaft brackets such as 4 and 5 may be similar. Each such switch is secured to mounting rails I and 3 by screws or bolts 66, the illustrated washers being used if desired. Each individual switch includes a frame member 65 (see also Figs. 4 and 5) having a one-piece armature and actuating plate 61 mounted thereon for actuation by an operating magnet I42. Each individual switch also has a contact bank '60 mounted on the frame portion 65 and including ten stackups of contacts 63, as seen best in Fig. 4.

Additionally, each switch has an eleventh, or

switching, stackup of contacts GI, and a so-called off-normal stackup of contacts 62.

In the. mounted position of the individual switches, the stackups of contacts thereof are respectively in alignment. The ten stackups 63 in bank 6|] of any individual switch comprise five pairs of such stackups-lst and. 2nd, 3rd and 4th, etc. Selecting shafts, SI-2, S3-4, S56, Sl-8, and S9--lll extend vertically across the front of the five pairs of stackups of bank 60 of each individual switch in the group. As will appear hereinafter, and as explained in the prior application previously referred to the arrangement is such that actuation of an armature of an individual switch effects the operation of a selective stackup of contacts of the switch only if such stackup of contacts has been selected by an appropriate movement of the associated one of the selecting shafts of such group of switches. Each shaft is arranged to be rotated slightly in either of two directions from its normal position in order to select one stackup or the other of the pair associated with such shaft in each of the switches of the group.

The eleventh stackup 6| of any individual member Q5. annealed magnet iron, for a portion of it must 4 I switch is termed a switching stackup, ftr it .is

used as illustrated best in Fig. 17 to switch the common incoming conductors from in association with the upper group of contacts in all stackups of the associated bank 60 into an association with the lower group of contacts in such stackups, when connection is desired with one of the sets of outlet conductors II to 20 of Fig. 17 rather than with one of the sets of outlet conductors I to I0. An additional selectin shaft SI I is arranged to be rotated slightly from normal position to select the eleventh (switching) stackup BI in all individual switches to thereby cause operation of the contacts in such stackup 6| to occur coincidental with the operation of any desired one of the ten stackups in the contact bank 60 of the switch, when the operating magnet of the desired individual switch is energized for this purpose.

The selecting shafts The selecting shafts shown in Fig. l are all of similar construction, a left-side view of shaft SI--2 being shown in Fig. 2. Each such shaft comprises essentially a metal tube at (Fig. 2) of appropriate length having an integrally formed web portion 44 (see also Fig. 4) through which the selective action of the shaft is performed in-' cidental to rotation of the shaft about its longitudinal axis.

At the lower end of the shaft Sl2 a bearing rod 65 is provided. The lower part of rod '85 may have a diameter substantially equal to the outside diameter of tubular portion 43, followed by a reduced-diameter portion which may be retained within the hollow interior of portion 83 by friction. Bearing pin is may be provided by turning down the lower end of bearing rod d5. or may represent a pin of bearing material inserted into a suitable drilled hole in member $5. The abutting end portion adjacent pin :35 is preferably somewhat rounded, as illustrated, to provide a simple thrust bearing to sustain the weight of the shaft on the upper surface of lower shaft bracket 5 around a suitable opening for receiving pin 46.

An armature-end bearing rod M is provided, being generally similar to the lower bearing Rod ll is preferably composed of serve as a magnetic return path, as will presently appear. Rotation of bearing member 51 with re spect to tubular shaft 43 and its web portion: 46 is prevented by rivets 48. j

Rod il has armature 49 secured thereto as by rivets 50. Armature 49 has a pair of wing portions 5I and 52 formed integrally therewith, arranged to be acted upon by the respective associated select magnets MI and M2. The normal relationship between wings 5I and 52 of any shaft and the associated select magnets (such as MI and M2) is illustrated in Fig. 3 where a portion of the upper shaft bracket 6 is broken away for this purpose.

Wing 52 of each armature i9 is provided with an integral arm 53 through which the shaft is normally maintained in a. desired normal position, and is returned to such normal position following temporary selectional rotation in'either direction.

As shown best in Fig. 2, arm 58 extends forward.

' aioaoos fromthetopportionofwinglltoa-n ntwhich (in assembled position) is well in-front of the 7 adjacent front line of'the upper-bracket I; thence extends vertically the top line of bracket 7 normally to provide 'ahorizontal portion into which the locating notch" (Fig.,3l;is out. At

this point, it may be noted that yielding springdriven rollers II are arranged-to l'ie within the notches u to maintain theselecting-shaft's yield-- ingly in normal position, and to cause their re-.

the upper shaft bracket 4, while the magnets for the second,

fourth, and sixth shafts, are locatedon the lower shaft bracket 5. This arrangement permits all MS andMl, M1 and M8, and!!! I,

shafts to be of exactly the same construction, any shaft turned so that the armature is at the top end, or reversed (armature at the bottom end) according to the position in the structure occupied by such shaft.- It may be noted that the right wing (corresponding to wing SI of any other shaft of the group) of shaft S is cut oil. This wing of shaft sll is not needed, for such shaft is associated with only one stackup (ii) of any switch and accordingly needs to be rotated in only one direction from its normal position.

Shaft brackets and bearings The shaft brackets l and are'generally similar to each other. Upper shaft bracket 4 com 'prisesa flat plate-like portion, seen in top view in Fig. 3, having the ends thereof turned down to to a above I; and thence extends.

form stiffening supports. The rear portion'of these down-turned ends is bent outwardly to form flat mounting portions l by which the bracketis held in engagement with the face of rack members l and I by screws 8. The rear portion in of bracket 4 is turned downwardly to form -a vertical surfaceon which select magnets such as MI and M2 are mounted by mounting screws 34 (Fig. 3). v The front part of the main plate portion of bracket 4 is provided with vertical bearingopenings for journally-receiving the upper ends urine selecting shafts. The second, fourth,

and sixth of these journal openings are comparatively small, as they directly receive the bearingpinportion 46 of first, third, and fifth of the bearing openings in shaft bracket 4 are comparatively large openings which threadedly receive adjustable bearing nuts 4!. One of these cross-section in upper shaft bracket 4' of the second group, whereat certain parts are omitted to giv a clearer view of the underlying structure.

Each bearing nut II is preferably formed of magnetic material, and contains a cylindrical recess which receives bearing rod 41. A slight annular clearance (.015 inch, for example) between rod 4! and the inside surface of bearing nut Ii insures that no frictional engagement occurs between the concerned parts except where a bearing pin 46 extends through its opening in nut ll. Lock nuts I: retain bearing nuts II in adiusted position.

bearing nuts II is' shown in' the concerned shafts. The

(Fig. 3).

. Each roller above the in the upper bracket 4' of the second switch bracket 4 or I (but left attached to portion II), the resulting openings being indicated at I2 Each roller bracket It includes a pair of opposed horizontal portions (interconnected by a rear vertical portion) con an opening for vertical pivot pins indicated at 22 to enable conductors to be attached thereto.

The front end of each roller arm 35 carries a roller 30 (rotatable around bearing pin 29) which engages notch 54 in the ssociated shaft-posi tioning arm 53 to retain the associated shaft normally in its desired normal position.

arm is spring 28, lying between the upper and lower side Part of spring 29, and

portions of the roller arm. Theforward end of spring is rests on a vertical bridging portion of the roller arm near the front to urge the arm and its attached roller 38 toward the associated resiliently retain such shaft in its desired normal position.

The rear portion of each spring 2! is formed at right angles to the roller arm and is held in engagement with a spring arm 23 by a rivet 26 which is passed through a washer 25, the rear pring arm 23. Sprin upper and lower horizonann II, and has rearwardly arm 2! lies between the tal portions of roller second shaft journalled I provided with a tension extending ears through which pivot pin 22 passes to retain that end of the spring arm 23 pivotally in position. The free end of each spring arm 23 is slotted horizontally to loosely receive the for- Ward portion of tension-adjusting screw 21. The front end of screw 21 is provided with a pair of lock nuts 28, preferably turned tightly together to act as a restraining shoulder for arm 23. A further lock nut 28 lies to the rear of arm l9, and is intended to be turned tightly against arm l9 to maintain screw 21 in any desired position of adjustment, such screw being threaded into an opening in arm l9. When the rear lock nut 28 is loosened and screw 21 is turned in one direction, the forward lock nuts 28 are drawn rearwardly to increase the tension which spring 29 exerts against the roller arm 35. Turning the screw in the opposite direction lessens this spring tension.

Each roller arm 35 has a, tab-like extension 38 for acting upon the adjacent one of the shaftoffnormal springs 30 through an insulating bushing to cause the springs 30 to make electrical contact with each other when the roller arm 35 is rotated slightly about pivot pin 22 incidental to the associated switch shaft being rotated into one Or another of its selective positions. The springs 30 may thus be used for pilo purposes to indicate to a control circuit that a shaft has been moved into a selecting position.

An arrangement is provided for adjusting the normal rotational position occupied by any selecting shaft. At each roller bracket it, this arrangement includes the hollow machine screw (or thimble) i through which retaining screw ll passes. Each such hollow screw l5 passes through a threaded opening in its respective tab H, and protrudes slightly from the front side of such tab, thereby determining the location of the rear surface of the concerned roller bracket E8. The

adjusted position of hollow screw i5 is maintained by lock nut Hi.

When it is desired that a roller arm 35 be adjusted, forwardly or rearwardly, to thereby bring the roller 38 carried thereby toward the front or toward the rear, its lock nut l5 and the mounting screw I! may both be loosened slightly to permit hollow screw l5 to be turned in the concerned direction. Roller bracket I8 is locked in the new position of adjustment by tightening lock nut it and screw ll. It should be noted that rotation of brackets 88 about retaining screw H as a pivot is prevented by contact between one main horizontal portion of any bracket [8 and the adjacent surface of the shaft bracket. For this purpose, the main horizontal portions of it are of suflicient length to bridge across the previously mentioned openings l2 in the shaft brackets, oc casioned by the formation of mounting tabs ll.

Guide brackets When there are a large number of switches in a group, guide brackets may be provided to maintain each of the then necessarily long selecting shafts (Sl2, S34, and so forth) substantially in alignment with respect to side-to-side deviations. Front-to-rear deviations are less likely to occur because of the strengthening effect of rearwardly projecting web portion 44. Moreover, a comparatively large front-to-rear misalignment can be tolerated, for the distance by which the finger arms 90 overlap a web portion i l may vary a substantial fraction of an inch without adverse efiect. Substantial lateral misalignment of a selecting shaft tends however to cause the concerned fingers 81 to stand too far to the right or to the left of the preferred normal (non-selecting) position.

One of the intermediate shaft-guide brackets is shown at 5 in Figs. 1 and 4. This bracket comprises essentially a horizontal plate-like member having down-turned tabs formed at the rear thereof by means of which it is held in engagement with mounting rails l and 3 by screws 58 passing through horizontally slotted openings to permit the guide bracket to be brought to the right or to the left into the desired position. The rear central portion of guide bracket 6 may be cut out to permit such bracket to be mounted closely below the adjacent individual switch mounted above it. Part 51 of bracket 6 may be bent down to form a vertical stiffening portion. Accurately sized and spaced notches are cut into the front portion of bracket 6 to freely receive the tubular portions 33 of the shafts. Each such notch is cut deep enough to accommodate the web portion M of the shaft. The width of each notch is preferably such that a shaft perfectly aligned from side to side is out of contact with the side walls defining the notch by a small amount, one sixty-fourth of an inch for example.

Each guide bracket 6 may have a front closure piece 55 mounted thereon and held in place by screws 56. These closure pieces, of course, may be left off indefinitely when desired, as during a period when the shafts need to be removed and subsequently replaced to permit repair or replacing of individual switches or to permit addition of individual switches to Partially filled groups. It will 'be understood that a guide bracket is not intended to maintain front-to-rear alignment of the shafts. It does, however, serve to limit the extent to which a shaft may be freely flexed (accidentally or otherwise) to the front or to the rear, whereby the probability of permanent distortion of an installed shaft from this cause is greatly reduced.

Switch construction The construction of the individual switches will now be described more in detail, reference being had particularly to Fig. 1 and Figs. 4 to 9. The frame portion 65 comprises a generally flat horizontal plate member having a pair of mounting tabs 64 turned up from the rear corner portions thereof through which the switchismounted on the front face rails l and 3 by screws 66. Frame 55 also has a depending tab i lfi (Figs. 5, and 9) on which operating electromagnet I62, having rear terminals M6, is mounted by means of screw I65 threaded into the core portion Hi3 thereof. The three large openings 19 through the frame 65 serve to receive nuts l3! (Fig. 15) threaded onto the lower end of screws ltd which hold the parts of contact bank 60 in assembled relation, while tapped openings 18 receive intermediate bank screws 332 by means of which the assembled bank Bil is mounted on the switch in the position indicated in Figs. 1 and 4.

It is to be noted that the front central portion of frame 65 is cut out, as seen in Figs. 4 and 5 to permit actuating plate 69 of armature 67! to lie within the confines of the frame.

Armature Bl comprises two principal portions-the horizontal actuating plate 69, underlying all stackups, and portion 68, the armature proper. Armature 61 has a second generally vertical portion H, located at the right end thereof, to complete the knife-edge pivoting and returning portion of the armature. The armapose.

' Il slant outwardly and I greater anglefrom vertical than is normally rethe left end ofportion it should be noted that V V trated .as formed of material of about-half of the the armature springs I,

ture is pivotally suspended on a pair of lugs 14 edge of parts 8 and 'H of the armature. Since the forward ends of springs 16 are bent down wardly at an angle as indicated in Fig. A, the retaining force applied by spring I6 toarmature 61 is rearwardly and downwardly. The armature can be removed from assembled position by merely drawing it forwardly until the lugs 14- and "are cleared, springs 16 yielding for this purposition. It may be noted face of frame 85, and consequently with the top surface of lugs II and I5 formed integrally therewith. Accordingly, there r ir'igbetween the armatureandsprmgs It as the armatu're is pivotally operated and restored under is a minimum of slidcontrol of magnet "2.

It may be noted that the generally vertical attractable portion I of thelarmature is connected "with the horizontal actuatingh portion 69 by a relatively narrow neck 12, tively' easy to adjust'the a rendering it comparangle between parts 68 and It, to thereby'adjust the stroke or angular,

movement of the armature incidental ,to an energization of magnet 2. A similar neck portion 13 interconnects actuating-part G9 and the righthand support part II. It is preferable that part quired for part in order that part II shall not require angular adjustment (incidental to'adjustment of the angle between parts 68 and 69) to maintain the pivotal contact between part H and upper front edge of frame 65 along the desired knife-edge line. 7

As best seen inFigs. 5, "I, andlilyactuating portion a of armature n has a stiffening de- 50 formed, therein at 10. This rib portion stops shortof the left-end of actuatingp'ortion't! to pressed rib portion avoid operating magnet I42,

undesired contact with which partially underlies 69. In this connection the armature is illusthickness ofthematerial from which the frame :is formed, and is so formed that the lower surface of actuating part 89 (exclusive of strengthening rib It) lies flush with the lower surface of main horizontal portion of frame 65.

In order to actuating part 69 of the armature against dropping below its normal horizontal. position, the armature is provided with a rearwardly extending, upwardly offset, part 84 (Figs. 5 and 6) .which overlies forwardly extend-- To replace the armature, it suffices to raisefth'e forward end of springs '16 while the armature is being placed in I that the horizontal line along which retaining downwardly at a slightly the depending actuating tabof the stackupfwheni through the slot,

whereby the concerned stackup is actuated responsive. to armature operation. first finger 81, forexample, the

Considering the left portion of this finger first and secondstackups.

' of; bank 60, but nor-.

openings 85 sufilcien'tly-v to cause operation of is pivoted at trated in Fig. 5 for the second finger. When pivot point, the left side of the first finger 81 bridges the central portion of the first slot 85, whereby the first stackup is selected for opera-- tion, subject to armaturetl operating to raise plate 69. On 1the'other'hand, if the first finger ll is turned in a, clockwise direction from its 3 normal position illustrated in Fig. '5, the righthand portion thereof comesover the middle part of the second slot 85, effecting selection of the second stackup of 'contacts'for operation along with the armature. l

'Finger stops It may comprise portions punched up (as by shear forming) from the material of actuating plate '8, having the form illustrated best in Fig. 16. Each such part 86 is preferably of such a width that it stops the movement of the associated finger 8] in either direction from normal position when the forward portion or the I I finger is approaimately under the center of the stickup into association with which it is brought by the movement.

Each of the five fingers 81 (see Fig. 5) of an a dividual switch may comprise a length of spring material (such as round wire) of a suitable diameter formed to the indicated configuration, which may be described as of a modified hairpin shape. The intermediate portion of the finger provides a pair of opposed nearly semi-circular portions which do not quite define a circle. This pivot, portion of the finger fits comparatively snugly aroundthe associated pivot 91.

Each pivot 9| may be formed by a process known as semi-perforating; that is, a circular section of the sheet material is punched partway through to raise the cyclindrical pivot portion 9| a desired distance above the surrounding fiat surface. This distance is preferably slightly in excess of the diameter of' the wire of which 7 fingers I! are formed, whereby a slight operating clearance I remains when the finger-retaining strip 92 is placed in position, supported by the top surface of pivots 9!. Strip 92 maybe spotwelded to the top of each pivot portion 9i as is indicated by the a: mark in Fig. 5.

is associated with the mally does not overlie either of the associated j either of the concerned stackups. .I'his finger. an intermediateportion, as illusturned counterclockwise about this intermediate The sixth finger 88 (the one cooperating with the eleventh, or switching, stackup 6|) is of the same construction as the five fingers 81, except that the rear left portion is oifset inwardly, as shown in Fig. 5, to displace the left stackupselecting and actuating portion of such finger to the right. This expedient is adopted because switching stackup GI is spaced an additional distance to the right of the tenth stackup in bank 60 to provide room for the common inlet terminals H3, as shown best in Fig. 4, while selecting shaft SII is spaced only a normal distance (one inch, for example) from the preceding selecting shaft, S9-I0. Stop member 88, associated with the sixth finger 88, is similar to stop members I 86, but is of reduced width because of the narrowed space between the side portions of finger 88 produced by the above-mentioned offset on one side of finger 88.

With further reference to the construction of the fingers, it will be noted that corner portions 93 are so located as to lie underneath retaining strip 92 in all rotational positions of the finger, whereby any tendency of a finger to tip (rotate about its longitudinal axis) is avoided.

The one-piece armature 61, with its principal parts 68 and 69, is preferably formed complete with its slots 85, stops 06 and 89, strengthening rib I0, pivots 9|, and finger-retaining strip 92, following which the five fingers 8I'and the sixth finger 88 may be placed inassembled position by inserting each such finger from the rear beneath the retaining strip 92 and straddling its pivot 9|. The arm portions 90 of the finger'spread apart for this purpose, responsive to the forward assembly pressure, again snapping together around pivot 9| when the desired position of assembly is reached. It is to be noted that the illustrated finger construction and finger-pivoting and retaining construct'on, besides providing a one-piece finger, spring, and control arms (90), permits the use of a very simple and economical arrangement for removably'pivoting the fingers in place.

Bank construction Referring now particularly to Fig. 1 and Figs. 4 to 16, the construction of the contact bank 60 of any individual switch will be explained more in detail.

The completed contact bank 60 is shown in top view in Fig. 4, in cross-sectional view in Fig. 9 (taken along line 9-9 of Fig. 4), and is shown partially diagrammatically in front view in Fig. 15. Each individual switch is provided with one of these banks 60, as is shown in Fig. 1, where each such contact bank is indicated for convenience merely as a rectangle.

Each bank 60 comprises a number of layers or strips held together between the upper and lower clamp strips I29 (shown in Figs. 14 and 14A) by screws I30, passing through the bank and threaded into bank nuts I3 I.

Besides the upper and lower clamp strips I29, bank 60 includes six pairs of contact strips, the uppermost strip of each pair having a construction as shown in Figs. 10, 10A, and 10B, the lower strip of such pair having a construction as shown in Figs. 11, 11A, and 11B. Below the lowermost pair of contact strips, there is assembled next an insulating strip shown in Figs. I2 and IZA, followed by the actuating strip shown in Figs. 13, 13A, and 13B, the latter strip lying directly on the lower clamp strip I29.

Referring now particularly to Figs. I0, 10A, and 103, the upper-contact'strip shown therein is indicated generally by the reference character I00. It comprises essentially an insulating strip 98 having ten contact blades IOI underlying it and extending across it to form a row. The form of thesection of each contact blade IOI overlaid by the common insulator strip 88 is shown in dotted outline. All the contact blades IOI of the strip may be similar, as indicated. They comprise five pairs, with the first blade of each pair being assembled in what may be termed a normal way, while the second blade of each pair is assembled reversed, in that it is rotated 180 degrees about its longest axis. This reversal is effected in order to bring the rear terminal extensions I05 of the two blades of a pair some distance apart (with the member I05 being oliset laterally from the contact-blade portion IN) to provide a wider field between the terminal members I05 of a pair to permit ready access to the side tabs I08 which are provided with notches as indicated, into which vertically extending inter-bank multipling wires may be soldered. Such vertically extending soldered wires are herein termed the bank multiple.

Strip 98 is preferably provided with retaining notches in its front and rear edges in which front tabs I03 and rear tabs I04 (formed integrally with the blade members) lie incthe assembled position of the strip. These tabs are preferably clinched inwardly as indicated to retain the respective parts in the illustrated assembled position.

The extreme rear portion of each of the terminal extensions I05 is shaped as shown at '01 to permit conductors (usually the outlet conductors common to all switches of a multipled group or subgroup) to be attached to these terminals at any desired one, or more, of the switches of a group connected together by the same bank multiple.

Insulating strip 90 of the strip assembly I00 is provided with five holes I08 for receiving bank screws I30 (Figs. 4, 9 and 15) and bank attach ing screws or bolts I32 (Fig. 4). The contact blades are spaced a substantial lateral distance away from the holes I00 to avoid electrical connection between the blades and the screws passing through the bank. Since the blades are assembled beneath insulating strip 98, the upper clamp member I29 of bank 60 may be assembled directly on the uppermost strip I00 of the bank.

Each contact blade IOI may be provided with a pair of depending contact points I02 in Figs. 10A and 10B, andsecured to the blades in any desired manner, as by welding. They cooperate with the twin contacts IZI of the adjacent lowercontact strip IIO (Fig. 11).

It may be noted that the blades IOI of the strip I00 are formed of comparatively thick sheet material in order that the contacts I02 carried thereby shall be comparatively rigidly supported to thereby serve substantially as fixed contact points, against which the respective underlying blades in the adjacent lower-contact strip (Fig. 11) may be brought firmly into engagement.

Referring now particularly to Figs. 11, 11A, and 113, the lower-contact strip shown therein is indicated generally by the reference character IIO. It comprises essentially a comb-like strip of spring material underlying insulating strip I I2 and secured to the latter by integral tabs II'I extending up through openings in the insulator strip and clinched over the top of the tabs Ill,

with a raised portion Ill as shown in Figs. 11 and 11B. Insulating strip II2 has five holes IIC therethrough of a size and spacing to align with the screw holes III in upper-contact strip III, while the underlying conducting back portion III of the comb structure has larger concentric clearance holes II5 therethrough to maintain the comb structure well out of electrical contact with the bank screws and the bank mounting screws.

The comb structure of contact strip IIII carries ten flexible blades II8, serving as flexible movable-contact springs for cooperation respectively with the ten fixed-contact blades IOI. Since blades Ill are interconnected electrically by theback portion III of the comb structure, such back portion may serve as a common conductor for the ten contact pairs represented by one'upper-contact strip I III lower-contact strip III. For sulating strip 2 stops short of the right-hand end of back portion III of the comb, leaving a clear space at for the attachment of the relatively rigid terminal blade "3, as by spot-welding at points x in Fig. 11. Each terminal blade I I 3 is provided extending across, the longitudinal center line of common portion III to provide a clamping action in the complete assembly to render the terminal blades 3 more rigid than if held merely by virtue of being s'ecured to the rather flexible extended right-end portion of back ill of the comb structure. This rigidifying clamping action, involving raised portion I ll of terminal blade I I3 is apparent upon reference to Fig. 8.

Each flexible contact blade II 8 carries a bushing II! at about its midpoint. This bushing has a head portion lying underneath its blade Ill. Each such bushing II! also has an upwardly extending part. This upwardly extending part of the bushing is intended to pass through the rear portion of openings I" (Fig. in the overlying contact blades III to engage the depending head portion of bushings II! of any strip I I0 which may be assembled above the one in question in the bank assembly. This column-like cooperation of bushings I I 9 is shown best in Fig. 9, where one stackup of bank ill is shown in sectional view.

and one underlying this purpose, in-

.the right-hand end of part In length that, when .tact bushing N9 of cated at a different distance from the end of the rear terminal extensions I05, so as to space the vertical wires of the bank multiple along planes parallel to the direction of extension of the contact blades.

The lowermost one of the six strips III in the illustrated bank 60 is underlaid by an insulating strip I24 (Figs. 12 and 12A) which keeps back portion II I of the comb structure of the lowermost strip Ilfl out of electrical engagement with the frame portion of the individual switch.

Actuating comb I (Figs. 13, 13A, and 13B) directly underlies insulator strip I24, and directly overlies the lower clamp strip I29 (Fig. 14) Actuating comb I25 comprises a common back portion I26 having flexible flngers I 21 formed integrally therewith. Each finger I 21 is of such a assembled in the bank II, it ends Just forward of the center of the con- .the immediately overlying contact blade Ill, the lower or head portion of such bushing H9 lying on the underlying finger I21 gear the forward end thereof, as shown in Fig.

As clearly seen in Figs. 13 and 13B, and as shown in the perspective view (Fig. 16), the front Contact blades III are bifurcated from a point just forward of bushings II! to the front end, forming twin arms I20 for each blade Ill. A

contact disc I 2I is secured to the 'front'end of each contact arm I2II. Twin points of'contact thus provided between eachmovable-contact blade III! and its respective overlying fixed-contactblade III, through cooperation of the twin contact discs I 2| of such blade H8 and the twin contact points "2 of such blade IllI. Preferably, the material of which the comb structure of strip III is formed is comparatively thin to render the blades III flexible to permit bending thereof between the front edge of the common portion III and the actuating bushing 9,, and to render the twin arms of any such blade II8 individually flex'ibleto insure that each exerts contact pressure substantially independent of the other when any contact blade H8 is raised by force exerted from below on its bushing II9.

' As previously noted, contact bank ill comprises six pairs of contact blade strips, each such pair being made up of a strip Ill and an underlying strip H8. All stripslll maybe of struction, and all strips ilfl may be of identical construction, except that each strip I" in the bank has its side has I (Figs. 10 and 4) 10- identical con-' to maintain the lower twin end of each flexible blade I21 of the actuating comb is provided with a down-turned actuating tab I2! through which the front end of the actuating spring may be raised subjectto the adjacent side of the associated finger 21 having been rotated underneath such actuating portion I22 to bridge the underlying slot 85. The bottom surface of any actuating portion I28 slopes slightly upwardly away from the normal position of the associated actuating finger 81 to insure that the finger which has selected and brought about the operation of the stackupof contacts will remain in its off-normal selective position so long as the actuating plate 69 of the armature remains raised, to thereby maintain the selectedstackup m operated position. 7

In the assembled actuating comb are position, blades I21 of the supported on the upper surframe 65, as shown in Figs. 9 and 16, whereby the depending portions I28 are maintained above the level of selecting fingers 81. Preferably, each of the contact blades I I8 is tensioned downwardly slightly to insure that it is normally out of contact with its overlying contact blade II. The total light downward tension of all of the flexible blades II8 in a stackup is imparted forward end of' the underlying actuating I21 through the medium of bushings 9. This downward pressure is resisted by blade I 21 by near the front. end

virtue. of its support at 82, thereof.

The eleventh sta'ckup The eleventh, orswitching, stackup 6| shown Fig. 7,

in Figs. 1 and 4, is shown in profile view in taken along section line 1-1 of Fig. 4; Generally, switching stackup 6I comprises three sets 7 such set including three contact blades arranged in transof contact blades I 36, I31, and I38, each fer, or break-make, assembly. The lower and upper blades of any such set of three are prefer ably of comparatively rigid construction, similar to blades IllI (Figs. 10 and 10A), while the intermediate blade of any such set relatively thin and flexible blade, similar to blades I I8 (Figs. 11 and 11A). Each such intermediate blade ofthe set of three is tensioned downwardly contacts carried thereto the blade is preferably a by normally in engagement with those carried on the upper side of the front end of the underlying rigid contact blade. Bushings are carried by the upper and lower flexible blades in stackup SI through which the intermediate portion of the flexible blades may be raised by pressure exerted upwardly onthe depending portion of the insulating bushing carried by the lowermost flexible blade. When this upward movement occurs, the flexible blades are raised upwardly together. Each thereupon moves out of contact with the underlying fixed-contact blade and into contact with its overlying fixed-contact blade.

Below the three sets of transfer, or switching, blades in stackup 6|, there is assembled an actuating blade I35 similar to actuating blades I21 (Fig. 13) This actuating blade is also supported on the upwardly offset portion 82 of switch frame 65 to maintain its depending portion I40 normally above the level of the associated selecting finger 88.

Basic alignment provisions Referring again to Fig. 1, basic alignment provisions illustrated therein will now be described.

The openings in mounting portions 1 (of shaft brackets l and 5) through which mounting screws 8 pass may be slotted' laterally (as shown for the left-hand opening for mounting screw 58 of shaft-guide bracket 6). Accordingly, the upper and lower shaft brackets l and 5, and the shaftguide brackets such as 6, may be adjusted laterally to the desired position of alignment on the rack before the mounting screws 8 and 58 are drawn up tight.

When the shaft brackets and shaft-guide brackets have been tightened in aligned position, holes 9 may be drilled through the mounting portions of the brackets, and through the underlying side rails I and 3 of the mounting rack, following which a locating pin may be driven into each such hole 9. With these brackets thus permanently mounted and aligned, the removal and replacement of the selecting shafts such as S l-2 to SII does. not operate to disturb the alignment of the shafts.

Each individual switch, with the shafts installed and adjusted to the desired neutral, or normal, position (by parts I5 to I1, Fig. 3), may be adjusted laterally into aligned position by virtue of the lateral slots through which mounting screws 66 pass.

Figure 17 Fig. 17 is a diagrammatic showing of electrical connections which may be made through bank 6|] of any individual switch by way of its eleventh, or switching, stackup 6|. In this drawing, the encircled numbers I to II represent the first eleven selective stackups of an individual switch, the upper switch of a group for example. The twenty sets of upwardly extending conductors labeled l to 20 respectively represent the twenty three-conductor outlet paths to which the three common inlet conductors I50 can be selectively connected. With stackup 6| in its illustrated normal position, the inlet conductors I50 are connected through the normal contacts in stackup 6| to the three upper horizontal conductors in the bank common to the ten stackups oi the bank, by way of the upper three of the six terminal blades 3 shown in Figs. 4, 8, and 11. It will be understood that the horizontal common conductors indicated in Fig. 17 are the back portions III of the comb structures illustrated in Fig; 11. When the inlet conductors I50 are to The closure of the upper three contact pairs in such stackup is efiective for the purpose stated, while the closure of the lower three contact pairs of such stackup is at that time a mere ineffective operation because the lower three horizontal conductors in the bank are normally open at the alternate contacts of the unactuated eleventh stackup B I When the inlet conductors I50 are to be connected with one of the outlet groups I I to, 20, the concerned one of the stackups I to II! of bank is actuated along with the eleventhstackup iii. In this operation, the lower three contact pairs of the actuated stackup I to Ill are efiective to complete the desired connection through the now effective alternate contacts of the actuated stackup 6!, while the closure of the upper three contact pairs of the actuated stackup I to Ill are ineffective because the normal contacts in stackup 6| are then in open condition.

It should be noted that the outlet conductors forming groups I to 20 in Fig. 17 are attached to' the rearmost terminals I01 (Figs. 4 and 10). The vertical conductors shown extending downwardly from bank BB in Fig. 1'? and labeled bank multiple represent conductors attached to the side tabs I06 (Figs. 4 and 10). These vertical conductors comprising the bank multiple may extend to and connect to the side tabs I06 of any desired number of individual switches, enabling the illustrated conductor groups I to 20 to serve as the common outlet paths for all the switches in the group.

Figure 18 Fig. 18 is illustrative of electrical connections involving a modified bank structure 60', which is similar to the bank structure 60 except that a fewer number of the strips of Figs. 10 and 11 are employed where only ten selections are to be made by the individual switch to which the bank is applied. Accordingly, in Fig. 18, each of the ten stackups has only three contact pairs, for mak-v ing only a single three-wire connection. In Fig. 18, the three inlet conductors I5I are attached directly to the common bank terminals H3, no

eleventh stackup 6i being required.

When conductors I5I are to be connected with any one of the ten sets of outlet conductors, shown in Fig. 18 as extending upwardly from the fixed contacts in the several stackups of bank 60, it suffices to close the three contact pairs of the concerned stackup. The bank multiple indicated in Fig. 18 is for the purpose noted above in connection with the bank multiple shown in Fig. 17.

It will be understood of course that the bank construction herein disclosed is applicable to any number of contact pairs in the individual stackups.

When the ten-selection arrangement of Fig. 18 is employed, the tapped holes 80 of Fig. 5 are obviously unused, for no stackup 6| is required. Additionally, finger 88 may be omitted from each individual switch, and shaft SII (used only to control the eleventh or switching stackups GI) may be omitted from the concerned group of switches.

QPERATION Operation of the disclosed switching arrangement will now be described.

(a) Stackup selection When any selective stackup of an individual switch is to be operated, such stackup must first be selected by a ing shaft in the concerned direction. Selection of the first stackup of all unoperated' individual switches of'the group occurs responsive to an energization of select magnet MI (Figs. 1 and 2). Left wing 5| of the associated armature 48 is thereby attracted into engagement with magnet MI whereby the first shaft SI-2 is rotated in a clockwise direction. Thereupon, web 44 of the shaft SI2 acts through arms 88 to rotate its associated fingers 81 counterclockwise about their pivots 9| (Figs. 5 and 16) until their respective associated finger stops 86 are engaged. The selecting shaft is preferably arranged to rotate through a slightly larger angle than the fingers, to insure that all fingers rotate a. sufficient amount. This excess shaft rotation is permitted by virtue of the inherent flexibility of the disclosed finger construction. The concerned arm 88 of each finger merely yields as soon as the finger engages its stop 86.

With the fingers associated with stackups I and 2 of all unoperated individual switches of the group rotated counterclockwise into engage-.

ment with their respective stops 86, as above outlined, the first stackup of bank 80 is selected in each unoperated individual switch of the group.

If any individual switch of the group is in operated condition when the selective action just described occurs, the raised condition ofthe actuating plate 89 of such switch causes the concerned (first) finger 81 of such switch to strike the side of the concerned depending actuating finger I 28 (see Fig. 16 for example) before the finger stop 86 of such finger is engaged. This action results merely in a slight additional flexing of the concerned arm 98 of such finger.

The above-described selective counterclockwise rotation of shaft SI-2 is accompanied by a forward rotational movement of arm 53 attached to the right wing 52 of the armature 49 of such shaft. The rear defining wall of the notch 54 of such arm 53 thereupon acts to move the associated roller 38 to the right, along with the associated roller arm 28. Roller 38 revolves about its bearing pin 39,and arm 35 pivots counterclockwise about pin 22, for this purpose. This action is performed against the tension of restoring spring 29.

When the shaft movement is nearly completed, shaft off-normal springs 30 are brought into engagement by tab 38 carried by roller arm 35.

(b) Switch operation Following the above described selecting action. and while the concerned magnet MI is maintained energized, the operating magnet I42 of any desired unoperated one of the individual switches is energized. The depending portion 68 (see Fig. 9) of such armature 61 is thereupon attracted rearwardly into engagement with the protruding end portion of core I43, rotating the armature structure about the knife-edge mounting arrangement hereinbefore described. This action rotates and raises actuating plate 69, together with all its fingers 81. Slots 85 in such actuating plate 89 pass around the depending actuating tabs I28 of all selective stackups of the concerned bank 88 without affecting such stackups, except in the case of the selected first stackup, where the slot 85 is bridged by the left side of the first finger 81, which has been placed below its actuating rotation of the concerned selectposition, the

18 tab I 28. The actuating tab I28 in the first stackup of this switch is raised by the now bridging portion of the left thereby raising the forward end of its actuating blade I2'I, causing the overlying column of bushings III (See Fig. 9) of this stackupto beraised, carrying with it the intermediate portion of all movable contact blades I II of the stackup.

When the armaturejstroke is only partially completed, the contacts carried on the forward end of the six fiexible contactblades Illof the stackup encounter those depending from the forward end of the respective associated fixed contact blades Ifll- The further movement of the armature causes flexing of the individual contact arms I28 (Fig.'11) of blades II8, keeping inmind that contact blades-[III III are made from material.

The lower contact pair I in ofi-normal stackup 82 '(see Fig. 6) is closed responsive to the armature movement irrespective of which stackup in bank 68 is selected and operated.

Operating magnet I42 of the individual switch is maintained energized for so long a time as the connection established by the individual switch is to remain intact.

(c) Shaft restoration The energized selecting magnet (MI in the assumed example) may be deenergized immediately following the operation of the individual switch. When this occurs, the associated restoring spring 29 acts to restore roller arm 35 and roller 38 to normal position, along with armature 49 and the shaft SI-Z to which it is attached. Roller 38 acts reversely in its roller notch 54 for this purpose. The normal position is reached when roller 38 strikes its lowest point in notch 54. The concerned contact springs 38 are now again in their separated condition illustrated in Fig. 3.

When the selecting shaft is returned to normal finger 81 through which the selected stackup in the concerned individual switch was operated is held in selecting position by the downward pressure exerted by the flexible blades in the actuated stackup. The holding of the finger is assisted by the previously mentioned bias cut of the lower face of tabs I28 as illustratedin Fig. 16. The concerned (left) arm of the first finger of the operated switch fiexes to the left as the selecting shaft SI2 returns to normal position.

relatively 1 thin flexible d) Switch restoration When the operating magnet I42 (of the switch operated as previously described) is subsequently deenergized, the armature thereof rotates back to it normal position by virtue of the weight of the actuating plate 69 thereof, assisted by the downwardly exerted spring tension in off-normal stackup 62 and in the operated selective stackup (stackup I in bank 60 in the assumed example).

When the descending actuating plate 69 lowers the first selecting finger 81 of the switch out of engagement with the depending actuating tab I28 of the previously actuated first stackup, such selecting finger is thereupon released, whereupon the spring action exerted through its two arms 88 causes the finger to realign itself with web portion 44 of the associated shaft SI2, to the position shown in Figs. 4 and 16.

side of the first finger l'l.

are constructed-of relatively heavy rigid material, while contact blades Selecting other stackups From the foregoing description it is clear how other stackups of the same switch, or any other switch of the group, may be accomplished. For example, if stackup 2 in bank 60 of any idle (unoperated) switch of the group is to be operated, the same shaft (SI-2) is rotated in the opposite direction responsive to an energization of selecting magnet M2, causing the fingers 8! controlled by such shaft to be rotated in a clockwise direction, to bring the right side of such selecting fingers beneath the actuating tab I28 of stackup 2 of each idle switch in the group. Then, when the operating magnet I42 of a desired idle switch is energized, stackup 2 of such switch is operated in place of stackup I. At this point, it may be noted that roller 38 and roller arm 39 associated with shaft SI-2 act as previously described except that the front defining wall of notch 54 in arm 53 operates at this time to move the. roller and roller arm, as the shaft moves in its counterclockwise selecting direction.

In a similar manner, the remaining stackups of the switches may be selected for operation-the second and third stackups by rotation of shafts 83-4, the third and fourth stackups by shaft 85-6, and so forth.

Selecting stackup 61 It will be understood that the stackup selection and switch operation such as considered in the immediately foregoing discussion (with the eleventh stackup iii of the concerned switch not being affected) makes effective connection only through the upper three contact pmrs of the concerned stackups l to In, as hereinbefore described in connection with Fig. 1'7.

When the lower three contact pairs of any one of the ten stackups in bank 68 of any switch is to be rendered effective for purposes discussed in connection with Fig. 1'7, the previously described selection of the concerned one of stackups l to It is accompanied by selection of the eleventh or switching stackup 6!. This selection is accomplished by energizing the eleventh selectin ma net Mi I. Wing 52 (the only wing) of armature 49 of shaft Si! is thereby attracted rearwardly, causing shaft Sii to be rotated in a clockwise direction to thereby rotate the associated fingers 88 (Figs. 4 and 5) in a counter-clockwise direction about their pivots. The offset left-side portion of each such finger B8 is thereupon brought effectively beneath the depending actuating tab 9 (Fig. 7) of stackup 6! of each idle switch in the group. As a result, when the operating magnet of a desired idle switch is then energized, stackup SI of such switch is operated along with the selected one of stackups i to ID in bank 60 of such switch. The operation of stackup 6i renders effective the lower three contact pairs of the operated one of stackups l to ill, as previously described in connection with Fig, 17.

By the herein described provision of a sixth shaft SH for a group of. switches, and the provision of the eleventh (or switching) stackup M for each switch of the group, the number of selections which can be made by the switch is doubled.

In the illustrated embodiment, the number of selections is increased from ten to twenty.

Although it is considered preferable that the disclosed switching devices be mounted in superposed relationship as shown and described, it will be understood that a group of switches may be mounted in any desired other position. For clarity and convenience, the following claims generand are not to be construed as limiting.

A portion of the novel subject matter disclosed herein is claimed in my divisional application for Selecting and actuating mechanism for a crossbar switch, Serial No. 88,274, filed April 19, 1949.

I claim:

1. In combination, stackups of contact blades arranged side by side, a common actuating member underlying said stackups, stackup-selecting means operable to preselect any said stackup for operation, means for subsequently moving the actuating member toward all said stackups, means responsive to such movement for actuating any preselected one of said stackups, and conductors so interlinking said stackups that actuation of any one of a plurality of said stackups completes one corresponding connection or another, depending upon whether one of said stackups not included in said plurality is actuated or not.

2. In combination, groups of contact members, means operable to preselect any one of said groups, an actuating member common to all said groups and movable to actuate any preselected group, and conductors so interlinking said groups that actuation of any one of a plurality of said groups completes one corresponding connection or another, depending upon whether one of said groups not included in said plurality is actuated or not,

3. In combination, a plurality of connecting groups of contact members, each such group being divided into two subgroups, a switching group of contact members, means operable to preselect any connecting group alone, and to preselect any connecting group along with the switching group, an actuating member common to all said groups and movable to actuate any preselected one, and conductors so interlinking the connecting groups with the switching group that actuation of any connecting group completes an effective connection through one subgroup or the other subgroup thereof, depending upon Whether the switching group is actuated or not.

4. In combination, a group of switches, each switch having groups of contacts individual thereto, said contact groups being arranged in pairs, group-selecting shafts common to all said switches and equal in number to the said pairs of contact groups of a switch, each such shaft being associated with corresponding pairs of contact groups in all said switches, each such shaft having an inactive normal position, and being movable therefrom alternatively in two directions to preselect the two contact groups respectively of the associated pair in any switch, each said contact group including two subgroups of contacts, a subgroup-selectin shaft common to all said switches and having an inactive normal position from which it is movable to an active selective position, such positions corresponding respectively to the two subgroups in any contact group, each switch having an actuating member operable to actuate any currently preselected contact group thereof, and means dependent upon which of its said positions is currently occupied by the common subgroup-selecting shaft, when the actuating member of any switch is operated, for rendering the corresponding subgroup of the actuated contact group effective to the exclusion of the other subgroup thereof.

5. In combination, a group of switches, each switch being operable to any one of a plurality of circuit-closing positions, each such switch pre-' operable to complete one prepared circuit or theother according to which of its alternative positions it assumes, and means including a movable selecting shaft common to and selectively associated with all said switching groups for causing the switching group of any operated switch to assume either desired one of its alternative positions.

6.- In combination, a switch including a mounting frame, a contact bank built up of superposed horizontal strips to provide columns of contact members through which desired connections may be made upon operation of the switch, said bank including upper and lower clamp strips, aligned openings being provided through all said strips, clamp members passing through certain of such openings and effective to exert inward pressure on the clamp strips to hold the several strips together as a preassembled contact bank, and mounting members passing through the remaining openings to secure the preassembled bank to the frame in operative relation to the remaining components of the switch.

7. In combination, a switch including a mounting frame, a contact bank built up of superposed horizontal strips to provide columns of contact members through which desired connections may be made upon operation of the switch, said bank including upper and lower clamp strips, aligned openings being provided through the strips, clamp screws passing down through certain of such openings and threadeclly entering nuts lying be low the lower clamp strip to exert inward pressure on the clamp strips to hold the several parts together as a preassembled contact bank, said frame having openings aligned respectively with said openings in the bank, the frame openings aligned with the clamp nuts being enlarged sufficiently to receive the clamp nuts of the bank, the remaining frame openings being tapped to receive bank-mounting screws, and mounting screws passing down through the remaining openings and threadedly entering said tapped openings in the frame to secure the preassembled bank to the frame in operative relation to the remaining components of the switch.

8. A switch bank including contact blades arranged in similar stackups lying side by side, each stackup including rigid contact blades interspersed with flexible contact blades, each rigid blade being comparatively thick to enhance its rigidity, each flexible blade being comparatively thin to enhance its flexibility, a body portion extending continuously across the rear of said stackups and serving to hold the blades in assembled position, comparatively thin lateral conducting strips in said body portion providing common connections for the respectively corresponding flexible blades in all stackups, each such strip being formed integrally with the flexible blades to which it is common, individual terminals for the rigid blades extending to the rear of the body portion, each such terminal being an integrally formed portion extending rearwardly from the concerned rigid blade, and comparatively thick terminal strips connected to said conducting strips, respectively, said terminal strips being held in assembled position by said body portion and extending laterally therefrom.

- operative association 9. In a switch bank wherein a body portion holds in assembled position contact blades arranged in stackups lying side by side, and wherein the body portion is built up of strips including I strips of insulated contact blades, all such strips being held together in aligned assembled position by retaining members passing therethrough, one such strip being a composite strip including an insulating strip and a conducting strip, said conducting strip having a contact blade for each stackup formed integrally therewith, said insulating strip having openings for receiving said retaining members, said conducting strip having respectively corresponding enlarged openings, said retaining members securing the last-named strips together in aligned superposed relationship as a composite subassembly strip.

10. In a switch bank wherein a body portion holds in assembled position contact blades arranged in stackups lying side by side, and wherein the body portion is built up of strips including strips of insulated contact blades held together in aligned assembled position by retaining members passing therethrough, one such strip being a compositestrip including an insulating strip and a conducting strip, said conducting strip having a forwardly extending contact blade for each stackup formed integrally therewith, arearwardly extending terminal blade secured to said conducting "strip, said insulating strip having openings for receiving said retaining members, said conducting strip having respectively corresponding enlarged openings, said retaining members securing said strips together in aligned superposed relationship as a composite subassembly strip.

11. In combination, a mounting plate comprising side arms interconnected by a rear bridge arm, contact stackups mounted side by side on said bridge arm and extending above the open space between said side arms, each side arm having a lug extending forward therefrom, a comsaid lugs, said combined 7 intermediately located generally horizontal actuating plate lying in said open space between said side arms, generally vertical end portions containing said apertures, and bent neck portions connecting said end portions respectively with said actuating plate, one of said end portions being extended downwardly to serve as an armature, an electrom'agnet mounted below the frame and arranged to operatively attract the armature rearwardly to rotate the actuating plate into with said stackups, and means flexibly retaining said combined structure from sliding forward off said lugs.

12. In combination, a mounting plate comprising side arms interconnected by a rear bridge arm, contact stackups mounted side by side on said bridge arm and extending above the open space between said side arms, a combined arma ture and actuating plate including an intermediately located generally ating plate, means pivotally retaining said end portions on said side arms, one of said end portions being extended downwardly to serve as an armature, and an electromagnet mounted below the'frame and arranged to operatively attract the armature rearwardly to rotate the actuating plate into operative association with said stackups.

13. A switching device adapted to be mounted the forward face of a pair of upright mounting ils, said device including a horizontal mounting plate of such a width that it overlaps both rails in mounted position of the device, integrally formed mounting feet turned over at the rear of the plate, forwardly extending stackups of contact blades mounted side by side on the plate at the rear thereof, a forwardly extending electromagnet mounted below the plate on a tab depending from the rear thereof, an armature for the electromagnet pivoted on the front of the plate to actuate the stackups, said armature being of such a width that it overlaps said rails, armature-retaining means located in overlapping relation with said rails, and terminals for the electromagnet and stackups extending rearwardly between the rails in mounted position of the device.

14. A composite selecting shaft for a row of shaft-controlled switches aligned with a shaftcontrolling electro-magnet, said shaft comprising a principal section having an end section fixed and aligned therewith, the principal section comprising a hollow tube having an integral side vane extending the full length thereof and forming the selective portion of the shaft, the inner end portion of said end section lying within the hollow principal section to hold the sections toin said bearings for rotation, each shaft having an armature fixed therewith near one end thereof between the brackets, electromagnets mounted in association with said armatures for rotating the respective shafts a limited amount, each shaft having an oifset side arm fixed therewith near,

one end thereof between the brackets and extendin'gfalong the axis of the shaft in front of L the a '5' bracket;

- row of hearings in such bracket, and means at said location cooperating with said side arm to 7 return the shaft to normal position following gether, the ends of the composite shaft being so formed as to cooperate with fixed bearings limiting endwise movement of the shaft while permittin rotation thereof; in the mounted position of the shaft, said end section extending across, and lying close to, the plane defined by the face of said electromagnet, the said principal section stopping short of said electromagnet, the side vane extending laterally through said plane, and an armature fixed to said end section and extending laterally across the face of said electromagnet.

15. In combination, a selecting shaft adapted to be journalled for rotation between a pair of mounting plates, a' control arm fixed with said shaft adjacent to one end thereof, said arm extending laterally sufficiently to clear the edge of the adjacent plate, then extending axially to a point beyond the plate, and finally extending laterally to a location opposed to a section of such plate, and restoring means adapted to act upon said arm at said location to restore the shaft to normal position following a limited rotational movement therefrom.

16. In combination, a group of selective switches mounted in superposed relationship, a bracket mounted at each end of the group, a selecting shaft extending across the group and journalled in said brackets for rotation, said shaft having an armature fixed therewith near one end thereof between the brackets, an electromagnet mounted on the associated bracket for rotating the shaft a limited amount, said shaft having an offset side arm fixed therewith near one end thereof between the brackets and extending vertically to a point beyond the associated bracket, such arm then extending horizontally to a location vertically aligned with a section of such bracket, and means at said location cooperating with said side arm to return the shaft to normal position following rotation.

17. In combination, a group of selective switches mounted in superposed relationship, a bracket mounted at each end of the group, each bracket having a row of bearings along the front edge thereof, selecting shafts extending across the group between said brackets and Journalled rotation.

18. In combination, a shaft journalled for rotation, an armature fixed therewith, an electromagnet having one pole associated with said armature to rotate said shaft, and structure providing a magnetic return path from said armature to the other pole of said magnet including a portion of the shaft and an annular gap surrounding the shaft and defined by a portion of said structure and the surrounded portion of the shaft.

19. In combination, a selective shaft journalled between a pair of brackets for rotation, an armature fixed therewith, an electromagnet having one pole associated with said armature to rotate said shaft, structure providing a magnetic return path from said armature to the other pole of said magnet including a portion of the shaft and an annular gap surrounding the shaft and defined by a portion of said structure and the surrounded portion of the shaft, and a cup member fixed with one bracket and freely receiving one end of the shaft, the bottom of said member containing one bearing for the shaft, the side walls of said cup being said portion of the structure which cooperates with the surrounded portion of the shaft to define said air gap.

20. In combination, a shaft journalled for rotation between a normal position and an operated position, a first cam member mounted for movement generally radially of said shaft, a second cam member fixed with said shaft in cooperative relationship With the first, spring means normally urging the first cam into engagement with the second to maintain the shaft in normal position and to return it to normal position following rotation to operated position, and means for adjusting the first cam tangentially of the shaft to change said normal position.

JOHN I. BELLAMY.

REFERENCES CHEF) The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,021,329 Reynolds Nov. 19, 1935 2,045,971 ,Stockfieth June 30, 1936 2,047,383 Reynolds July 14, 1936 2,120,408 Hickman June 14, 1938 2,120,413 Matthies June 14, 1938 2,166,764 Matthies July 18, 1939 OTHER REFERENCES Figs. 26 and 2'7, page 44 of volume 3 of Telephone Theory and Practice by Miller, the Mo- Graw-Hill Book Co., Inc., 1933.

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