US1997655A - Switching mechanism - Google Patents

Description

April 16, 1935.

S. B. SANFORD ET AL SWITCHING MECHANISM Filed April 9, 1934 2 Sheets-Sheet l FIGZ FIG!

ATTOQNEY April 16, 193.5. s. B. sANFoRD E1- AL 1,997,655

SWITCHING MECHANI SM Filed April 9, 1934 2 Sheets-Sheet 2 ATTORNU Patented Apr. 16, 1935 UNITED STATES PATENT ori-'ICE SWITCHING MECHANISM Jersey Allllioation April 9, 1934, Serial No. 719,717

4 Claims.

This invention relates to switching mechanisms.

One feature of the invention is the provision of a switching mechanism having great versatility with respect to its contact arrangement and the manner in which it may be operated.

Another feature of the invention is the provision of a switching mechanism of the spring blade type in which a comparatively large number of spring blades may be employed Without dilculty, and with uniform accuracy and reliability in the operation thereof.

A third feature of the invention is the provision of a contact assembly for switching mechanisms of the spring blade type that is easily and economically constructed and assembled.

Other features and advantages will become apparent from the specification and the accompanying drawings.

The invention involves one or more contact units each comprising a plurality of spaced metallic spring blades each of which has a cantilever mounting. The free end of at least one of the spring blades of each contact unit is movable with respect to the free end of at least one of the other spring blades of such vcontact unit. The spring blades the free ends of which are movable are hereinafter termed movable spring blades, and the other spring blades with respect to which the free ends of the movable spring blades move, are hereinafter termedstationary spring blades. Each movable spring blade has a Contact near its free end arranged to engage with, or disengage from, a corresponding contact on the stationary spring blade of the same contact unit, thereby to complete or break an electric circuit to which the spring blades of such contact unit are connected. Provision is made to mount a variable number of contact units in a row or column with their at sides approximately parallel. For actuating each movable spring blade a member, termed push bar, is provided along the ends of the spring blades and is arranged to move perpendicularly to the planes of the spring blades. The push bar is provided with suitable operative connections between it and the free ends of the movable spring blades so that, when the push bar is moved from its initial position by a suitable actuating mechanism (electrical or mechanical), each such movable spring blade is moved to effect the contcmplated change in the electrical circuit or circuits associated therewith. Due to the common actuator for the movable spring blades to which each is directly operatively connected. all the (Cl. 20o-104) movable spring blades, regardless of their number, are moved coniointly. In the illustrated. embodiments of the-invention, the movable spring blades are formed so that they extend beyond the ends of the stationary spring blades and the push bar is positively locked to each such extension. As a consequence, the movable spring blades are definitely spaced and secured at their free ends aswell as at their base ends. and are caused at all times to operate as one unit.

In one of the illustrated embodiments of the invention, provision is made for mounting two rows or columns of contacts side by said when, due to space requirements or other reasons, a single column is not possible or desirable. `In this embodiment the contact units are actuated by electromagnetic means through the intermediary of a movable armature which is in engagement with the switching mechanism push bar. When two columns of contact units are provided, the push bar of each column is in engagement with the armature, but with diierent portions or arms thereof. These different armature portions or arms are arranged so that each may be bent with respect to the other in the d1- rection oi motion of the push bars so as to adjust the initial position of the push bar for one column of contact units with respect to the push bar for the other column of contact units.

In the drawingst- Figure 1 is a side elevation of an electromagnetically actuated switching mechanism in accordance with the invention;

Figure 2 is an end view oi the same taken along the line 2-2 of Figure 1;

Figure 3 is a section taken along the line 3 3 of Figure 1;

Figure 4 is a section taken along the line 4-4 of Figure 1;

Figure 5 is a plan view of one of the movable spring blades;

Figure 6 is a plan view of one of the stationary spring blades;

Figure 7 is a section taken along the line 'l-l of Figure 3, illustrating the manner of securing together the ends of the movable spring blades;

Figure 8 is a section taken along the line 8-8 of Figure l, illustrating details in the mounting of the spring blades;

Figure 9 is a fragmentary side elevation of a mechanically actuated switching mechanism in accordance with the invention; and

Figure 10 is a section taken along the line lll-l0 of Figure 1, illustrating the manner of aligning the spring blades of the contact as sembly.

Referring to Figures 1-8 of the drawings, the electromagnetically actuated switching mechanism therein illustrated comprises a contact assemblygenerally designated 20, an electromagnetic actuating mechanism generally designated 2|, a metallic base member 22, and a cover 23.

TheL electromagnetic actuating mechanism comprises a magnet coil 24 provided with a headed core 25, the core being secured at lts base to a frame 26 and base member 22 by means of a screw 21. Screw 21 also serves to secure frame 26 to base member 22, a doweled-out portion 30 of frame 26 tting into a corresponding recess in base member 22 so that the frame and base member are held against rotation. Suitable apertures are provided in frame 26 and base member 22 for receiving insulating bushings 3| through which extend terminals 32 of magnet coil 24.

Frame 26, made of magnetic material, is formed with an extension 33 parallel to the axis of core 25, part of this extension being shaped to provide a support 34 for a contact assembly 20 as hereinafter appears. The end of extension 33 is formed with a raised knife edge 35 in two sections, one on either side of an intermediate portion of frame extension 33 adjacent the longitudinal centerline thereof.

An armature generally designated 35 is provided for magnet coil 24, the armature having a core-attracted portion 31 and two arms d and lil. Arms 40 and 6| 'are bent as shown for arm il in Figure l so that they are substantially parallel to the axis of core 25, the armature being pivotally supported by the two sections of knife edge 35 engaging arms 40 and ll at their point of bending. Arms 40 and il are shaped as shown in Figures 3 and 4, to form a loop having a side parallel to knife edge 35, the arms termihating adjacent each other with a space between their butt ends. The termination of arms 66 and 4| is preferably offset from the longitudinal centerline of the frame extensin 33, as illustrated in Figure 4, for reasons which hereinafter appear.

A keeper, generally designated 62, is provided to retain armature 36 in position. Keeper d2, preferably of brass or other non-magnetic material, is secured to frame extension 33 at the longitudinal center line thereof by means of a brass screw 43. Keeper 42 occupies the space between the two sections of knife edge 35 and is bent upwardly so that it emerges between the arms 40 and 4I substantially at the point of bending thereof. At this point keeper 42 is provided with two shoulders 44, one on each side thereof, extending over arms 40 and 4I, and cooperating therewith to retain the armature in position. It is preferred to further extend keeper 42 and bend such further extension 45 downwardly, as illustrated in Figure 1, and provide thereon an adjusting screw 46 with lock nut 41 for adjusting theinitial, outward, coil-deenergized position of armature 36. It also preferred to provide an adjusting screw 50 with lock nut 5I on the core-attracted portion 31 of armature 36 for adjusting the ultimate inward position of the armature when magnet coil 24 is energized.

Contact assembly 20 comprises a plurality of metallic spring blades mounted in cantilever fashion on support 34 of frame 26 by two screws 52. 'Ihe spring blades in the illustrated contact assembly are designated as follows-,starting with the bottom blade, which lsadjacent support 34:

58-terminal blade. 54-stationary spring blade. SE-movable spring blade. 56-stationary spring blade. 61-movable spring blade. 58-statlonary spring blade. Ell-movable spring blade. li--stationaryy spring blade. 6| movable spring blade. 62-stationary spring blade. 15S-short spring blade.' 84-special spring blade.

Contacts 65 are provided at the outer or free ends of these spring blades. These contacts cooperate in the manner hereinafter described. Terminal blade 53 is preferably in contact with support 34 and is provided to enable grounding of 'frame 26, when desired. Between adjacent blades,

and between the uppermost blade and a. metallic cap plate 10 directly beneath the heads of screws 52, are provided insulating spacers 1I. These spacers are provided with shoulders 12 (see Figure 8) around each aperture therein for screws 52 so that the blades are completely insulated from screws 52. A convenient method of obtaining shoulders 12 is to shear a cylindrical portion of spacer 1l around each aperture therein by means r" of a punchl working in a die the formation of which is such that the sheared cylindrical portion is not removed from the spacer but is displaced an amount sumcient to form shoulders 12.

Stationary spring blade 54 is formed as shown in Figure 6. There is a base or support portion 13 having apertures 16 for screws 52 and spacer shoulders 12, a blade portion 15 extending in one direction from the support portion and a terminal tab 16 extending in the other direction from'the support portion. It is preferred to form stationary spring blade 54 so that one side thereof, when viewed in plan as in Figure 6 is straight, with blade portion 15 decreasing in width from the support portion to the end of the blade portion, as illustrated. Contact 65 for spring blade 5d is mounted adjacent the free end of blade portion 15 so that the working portion of the contact projects above the upper surface of the spring blade. A convenient manner of mounting contact 65 is by inserting a short stem formed thereon through a suitable aperture in the spring blade and then turning over the stem at the underside of the blade. If desired, however, contact 65 may be spot welded onto the blade.

Movable spring blade 55 is formed as shown in Figure 5. There is a base or support portion having apertures 8| for screws 52 and spacer shoulders 12, a blade portion 82 extending in one direction from the support portion and a terminal tab 83 extending in the other direction from the support portion. It is preferred to form movable spring blade 55 so that one side thereof, when viewed in plan as in Figure 5, is straight, this side being the side opposite the straight side of stationary spring blade 54. The outer or free end of blade portion 82 of movable spring blade 55 is formed with a rectangular aperture 84 and a circular aperture 85. Contact 65 for movable spring blade 55 is mounted adjacent the end of blade portion 82 but at a lesser distance from support portion 88 than rectangular aperture 84 in a manner similar to the manner by which the corresponding contact is mounted on stationary spring blade 54. Contact 65 for movable spring blade 55 is, however, mounted so that its working portion projects,

beneath the under surface of the spring blade.

Stationary spring blades 56, 56, 6U and 62 are similar in construction to stationary spring blade 54 except that, as illustrated in Figure l, stationary spring blades 58, and 52 have their contacts mounted so that the working portions thereof project beneath the under surfaces of the blades. If desired, contact for stationary spring blade 62 may be provided with a long stem which, upon being peened over at the upper surface of the blade, results in a head 86 extending above the upper surface of spring blade 62. The function of head 86, when provided, is hereinafter described.

Movable spring blades 51 58 and 6| are similar in construction to movable spring blade 55 except that, as illustrated in Figure 1, spring blades 59 and 6i have their contacts 65 mounted so that the working portions thereof project above the upper surfaces of the blades, and spring blade 51 has contacts 65 with working portions thereof extending above and below both sides of the spring blade. This may be effected by utilizing a contact 65 having a long stem and peening over the stem with a suitable cup-shaped tool.

Special spring blade 64 is similar in construction to stationary spring blade 54 except that its contact 65 is mounted so that its working portion projects beneath the under surface of the blade, and also, so that its contact 65 is mounted at a point further from the end of the blade than is the contact on blade 54. In addition, blade G4 is provided with an insulating distance pin 81 mounted thereon to project beneath the under surface of the blade, a portion of the distance pin projecting up through an aperture in blade 64 and being peened over so as to secure the distance pin to the blade. Distance pin 81, preferably cylindrical in shape, is of such length that the bottom thereof engages spring blade 62. The bot tom surface of the distance pin may be suitably recessed, as illustrated in Figure 1, so that the distance pin fits over head 86 on blade 62, if such head is provided, to assist in maintaining the distance pin in position.

Short spring blade 63 is similar in construction to stationaryspring blade 54 but with a shorter blade portion, as illustrated in Figures 1 and 3, so that the end of blade 63 does not engage distance pin 81. Contact 65 on short spring blade 63 is mounted so that the working portion thereof projects above the upper surface of the blade, and is positioned to cooperate with the contact on special spring blade 64.

'I'he various spring blades of contact assembly 20 are illustrated in Figures 1 and 2 in their initial positions, that is, when coil 24 is deenergized. In this position, the contacts of stationary spring blade 54 and movable spring blade 55 are in engagement; the contacts of stationary spring blade 56 and movable spring blade 51 are in engagement and the contacts of movable spring blade 51 and stationary spring blade 58 are disengaged; the contacts of movable spring blade 59 and stationary spring blade 60 are disengaged; and the contacts of movable spring blade 6i and stationary spring blade 62 are disengaged and the contacts of short spring blade 63 and special spring blade 64 are in engagement, with distance pin 81 resting upon stationary spring blade 62. Upward motion of the outer end of movable spring blade 55 causes the disengagement of the contact thereon from the corresponding contact on stationary spring blade 54. Upward motion of the outer end of movable spring blade 51 causes first the disengagement of the contact thereon from the corresponding contact on stationary spring blade 56 and then the engagement of the contact on movable spring blade 51 with the corresponding contact on stationary spring blade 5l. Upward motion of the outer end of movable spring blade 5! causes the engagement of the contact thereon with the correspondlng contact on stationary spring blade 60. Upward motion of the outer end of movable spring blade 6i causes first the engagement of the contact thereon with the corresponding contact on' stationary spring blade 62 and thenthrough the action of distance pin 81, the separation of the contact on special spring blade 64 from the corresponding contact on short spring blade 63.

To eiIect the upward motion of movable spring blades 55, 51, 58 and 6| in unison, the outer ends of these blades are actuated by a push bar 68. Push bar 96 is positioned with its longitudinal axis parallel with screws 52 and is arranged for longitudinal motion. 'I'his motion is obtained in the illustrated electromagnetically actuated switching mechanism by having the lower end of the push bar engage armature arm 46 or 4I. In the illustrated switching mechanism employing one row of spring blades mounted at center of support 34, the lower end of push bar rests on armature arm 40, as appears in Figure 4. Push bar 90 is operatively associated with the outer ends of each of movable spring blades 55, 51, 59 and 5I in such manner that the outer end of each of these movable spring blades remains in its initial, illustrated position when magnet coil 24 is deenergized, but is moved upwardly to its other position, conjolntly with the upward motion of the outer end of each of the other movable spring blades, upon the energization of magnet coil 24 and the consequent raising of push bar 90. Such operative connection of push l.

bar 90 with the outer end of each movable spring blade may comprise a shoulder or arm on the push bar extending laterally therefrom under the outer end of each movable spring blade so that when the push bar is raised each such shoulder v or arm raises the outer end of the movable spring blade with which it is associated. 'I'here may also be provided a shoulder or arm on the push bar extending laterally therefrom above the outer end of each movable spring blade so that when the push bar is lowered, each such shoulder insures that the movable spring blade with which it is associated is returned to its initial position. The preferred construction for operatively associating push bar 90 with the outer end of each movable spring blade is the illustrated construction, shown in detail in Figure 7, with which Figure 5 is also to be considered. Push bar 96, of insulating material and rectangular cross section, is formed at appropriate intervals along one side with a plurality of transverse slots 9i, into each of which f'lts an edge 92 of rectangular aperture 84 at the end of each movable spring blade. Along the side of push bar 90 opposite the slotted side is positioned a key strip 93, also of insulating material, the key strip being secured to the push bar as by a rivet 94. In assembling these parts, push bar 90, without key strip 93 attached thereto, is first inserted through the rectangular aperture 84 in each of the movable spring blades that are to be actuated jointly by the push bar. The push bar is then moved transversely in these apertures in a direction toward screws 52 so that edge 92 of each movable spring blade is fitted into the appropriate slot 9| in the push bar.

Key strip 93 is then inserted in apertures 84 along the back of push bar 90 and secured to the push bar by rivet 94. Key strip 93 is of such thickness that when it is secured in place along the back of push bar 90, it, in conjunction with the side of each rectangular aperture 84 opposite to side 92, maintains push bar 90 in the position, as illustrated in Figure 7, in which the movable spring blades are tted into the slots on the push bar.

In assembling 'contact assembly 20 it is important that contacts 65 of the various spring blades are properly positioned so that the working portions of these contacts cooperate properly. With the illustrated construction, the proper positioning of the various spring blades so that their contacts will cooperate is quickly and readily eiected. The manner by which this is done is shown in Figure 10, which is a section through the ends of suflicient of the spring blades illustrated in Figure 1 as serves to indicate the method. Before screws 52 are nally tightened, a straight guide pin 95, indicated in dot-and-dash outline in Figure 10, is inserted through the circular aperture 85 in each of the movable spring blades. Each of the stationary spring blades is moved so that its edge is in contact with guide 'pin 95, whereupon screws 52 arevnally tightened to secure the contact assembly in position, and the guide pin is removed.

The terminal tabs of the various blades extend through a suitable aperture 96 in base member 22. To facilitate connection to such terminal tabs, they may be shaped with cut-outs as illustrated or provided with small apertures into which are hooked the connecting Wire ends, the connections to the terminal tabs in each instance preferably being soldered. If desired, the terminal tabs may be provided with such apertures as well as with the illustrated cut-outs.

Base member 22 is formed with an outwardly projecting portion at the top thereof and with an outwardly projecting portion 0| at the bottom thereof. Cover 23, enclosing contact assembly and electromagnetic actuating mechanism 2|, fits over base projections |00 and |0| and is frictionally held in place by the action of a spring |02 secured to base projection |00.'

Base member 22 is also formed with a rearwardly projecting portion 03 near the top thereof and with two rearwardly projecting portions |04 near the bottom thereof, only one of the two base projections |04 appearing in Figure 1. The entire unit illustrated is arranged to be supported by two horizontally extending rectangular cross bars |05 and |06, these bars being parallel to base member 22 with bar |05 near the top of the base member and withbar |06 near the bottom of the base member. A threaded aperture |91 is provided in base member 22 adjacent its top for receiving a mounting screw ||0, a washer being provided adjacent the head of such screw. Washer is in engagement with the end of base projection |03 and also with cross bar |05, so that tightening of mounting screw |0 secures the upper portion of base member 22 to cross bar |05. Similarly, two threaded apertures ||2 are provided in base member 22 adjacent its bottom for receiving mounting screws 3, these screws being provided with washers ||4 so that, upon tightening of screws I3, the lower portion of base member 2 2 is secured to cross bar |06.

Considering the operation of the illustrated switching mechanism, it is believed clear that upon energization of magnet coil 24, the core attracted portion 31 of armature 36 moves toward core so as to effect clockwise rotation of armature 36 about knife edge 35. Such clockwise rotation of the armature raises armature arms 40 and 4|, and results in moving upwardly the push bar 90 and key strip 93. Such upward motion of the push bar is imparted conjointly to the outer ends of movable spring blades 55, 51, 59 and 6|. Upward motion of push bar 90 causes the engagement of certain contacts and the disengagement of other contacts, as previously described. Upon deenergization of magnet coil 24, each spring blade which has been displaced Afrom its initial position, returns, due to its resiliency, to such initial position. The return to their initial positions of the movable spring blades connected to push bar 90 results in lowering the push bar to its initial position and in returning armature 36 to its initial position.

Attention is directed to the fact that contact assembly 20 may comprise any number and arrangement of spring blades. The contact assembly shown in Figures 1 and 2 of the drawings illustrates the four principal types of contact units that may be employed, i. e.,

1. Breaking unit (spring blades 54,

2. Break and then make unit (spring blades 56, 51, 58). 3. Making unit (spring blades 59, 60). 4. Makeand then break unit (spring blades 6|,

62, 63, 64).A It is clear that Contact assemblies may readily be built up utilizing one or more of anyo/f such contact units, or of any combination of such `contact units, as are desired. `In the event it is desired to employ contact units having a total number of springblades greater than may be accommodated in one row, as illustrated, attention is directed to the fact that provision is made to arrange the spring blades in two rows, side by side. This is eected by providing support portion v34 of frame 26 with three pairs of threaded apertures- ||5, ||6 and II1-for receiving screws 52 (see Figure 4) the center pair H6 being utilized when one row of spring blades is employed and the two outer pairs I5 and ||1 being employed when two rows of spring blades are employed. When two rows of spring blades are employed, the push bar and key strip along the'ends of the spring blades of one row engage armature arm 40, as indicated in Figure 4 by the dot-and-dash rectangle |20, while the push bar and key strip along the ends of the spring blades of the other row engage armature arm 4|, as indicated in Figure 4 by the dotand-dash rectangle i 2|. thus actuated conjointly by armature 36, with the result that the spring blades in the two rows are also actuated conjointly. To provide for any inequalities that may exist between the two rows of spring blades, or for an advance operation of the spring blades in one row with respect to the operation of the spring blades in the other row, (if desired) armature arm 40 may be displaced upwardly or dOwnwardly relative to armature arm 4 'since the two arms, as previously explained, are not joined. So that push bar and key strip 93 may, when only one row of spring blades is employed, engage only one armature arm and not be affected by any relative displacement of the ends of armature arms 40 and 4|, it is provided that the termination of these arms is offset from the longitudinal center line of frame extension 33, as illustrated in Figure 4.

It is preferred that, in the manufacture ofthe springblades, certain of them be bent a definite The two push bars are itt newness amount and in a definite direction. in anticipa tion oi the particular' uses to be iliade of such spring blades. Thus. in the illustrated contact assembly. movable spring blades 59 and 6| are straight. uhile movable spring blades 55 and 61 are eat-li provided with an initial downward bend. Also, stationary spring blades 60 and 62 are straight, while` stationary spring blades 54 and 56 are cach provided with an upward bend. Stationary spring blade 56 und short spring blade 63 are provided with upward bends and special spring blade 64 is provided with a downward bend. As a result of such pre-bending of certain of these spring blades. there are a number of different spring blades which are required to be carried in stock. It is to be observed. however. that this number is not large. It is to be noted that stationary spring blades 54 and 56 are identical, movable spring blades 59 and 6| are identical, and stationary spring blades 50 and 62 may be identical. so that the entire contact assembly of eleven spring blades illustrated in Figure l arranged to provide one unit of each of the four principal contact units, employs only eight difterent stock blades. based on two primary blade forms.

Referring to Figure 9 of the drawings, the mechanically actuated switchingmechanism therein illustrated comprises a contact assembly generally designated |30, contact assembly supporting mechanism generally designated |3|, and mechanical actuating mechanism generally designated |32. Contact assembly |30 is made up from parts similar to those employed in contact assembly 20 of the electromagnetically actuated switching mechanism of Figures l-8, but, for purposes of illustration. a simpler contact assembly, comprising two making contact units, is shown. It comprises four spring blades |33, |34, |35 and |36. of which spring blades |33 and |35 are similar tovspring blade 59. and of which spring blades |34 and |36 are similar to spring blade 60. The outer ends of spring blades |33 and |35 are operatively connected to a push bar |31 that is similar in construction to push bar and which is provided with a key strip |33 similar to key strip S3. Insulating spacers |40, similar to insulating spacers 1|, are provided to insulate the spring blades; and screws t4t, similar to screws 52, serve to fasten together the spring blades of the contact assembly and to provide a means for mounting the contact assembly upon a suitable shelf |42. In the illustrated arrangement, an additional insulating spacer |40 is employed at the bottom oi the assembly and then, underneath that, a threaded clamp plate |43 is provided, so that contact assembly |30 is clamped together between clamp plate |43 and a cap plate |44. The contact assembly may then be handled without danger of its coming apart.

Contact assembly |30 is mounted upon shelf |42 by inserting the ends of screws |4| through suitable apertures in the shelf and then screwing up on nuts |45. Contact assembly supporting mechanism |3| includes, in addition to shelf |42, an operating finger |46 and a stop plate |41 positioned between clamp plate |43 and shelf |42, stop plate |41 being next to the shelf. Operating nger |46 is of spring material and has mounted at its outer end an impact member |50. In the initial position of the parts, as illustrated, the lower ends of push bar |31 and key strip ,|38 engage the outer end of operating ringer |46, with the base portion ofl such finger resting against motion Zor the push bar and key strip. impact member |50 is arranged to be engaged by any suitable mechanical actuating mechanism |32 for displacing operatingl linger isb upwardly, and thereby cause the engagement oi the contacts on movable spring blades B33 and |36 with the corr iacts on stationary spring blades E34 and |36. respectively; As illustrative oi such a mechanism. mechanism |32 is shown as comprising a rotating shaft |5| on which is clamped an arm |52 having a cam portion |53. The arrangement is such that rotation ol shaft I5i causes engagement oi cam portion 53 with impact member i60 to effect the operation of the contact arsembly in the manner previously described.

It is to be observed that any number of contact units-even when they are arranged in one rowmay be utilized in switching mechanisms'. in accordance with this invention without faulty operation, in spite of possible manufacturing variations in the sizes and thickness of the various parts employed. This is due to the fact that the movable spring blade of each contact unit i; actuated directly by the push bar, and conjointly and in parallel with the movable spring blade of each of the other contact units. In addition. it is to be observed that notwithstanding the loss of resiliency of any movable spring blade or a tendency of any spring blade to assume an initial position other than the one it is intended to assume, such movable spring blade is maintained in its intended initial position by the push bar, and actuated and returned to its intended initial position upon movement of the push bar, as if everything was normal with such spring blade. The actuation of a recalcitrant movable spring blade by the push bar needs no explanation. The maintenance of a recalcitrant movable spring blade in its originally intended initial position is due to the fact that the push bar is subject to the algebraic sum of the tendencies of all the movable spring blades, so that any abnormal tendency of a movable spring blade is submerged by the normal'tendencies of the other movable spring blades. y

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof,

it is intended that all matter contained in thel I above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a switching mechanism; at least three metallic spring blades disposed with their fiat sides opposite each other in substantially parallel planes, each of said blades having a base end and a free end and having an electrical contact surface near its free end for cooperation with the contact surface of an adjacent blade, and each of certain of said blades, not less than two, having an aperture therein near its free end; means providing a cantilever mounting for each of said blades at its base end and insulating said blades `from each other at their base ends; an operating member, having spaced slots on one side thereof, positioned in said apertures in said certain blades so that an edge of each of said apertures fits. in a slot in said operating member thereby to connect and secure the free ends of said certain vblades in xed spaced relation and cause all said certain blades to operate as a unit; means, effective after said operating member is positioned in said apertures with the edges thereof iittcd in saidslots, to'r retaining said operating member in such position with respect to said certain blades: and 'means for im; parting motion to said member to bend' sa'i'd spring blades connected thereto'and therebyi# reet a change in therelative positions otth cooperating contact" surfaces of -saidspring blades.

2. A switching mechanism comprising; is, piurality of contact units each havinga-movable spring blade and one or more other spring blades', each of said blades having a baseend 'and anouter or contact end, and eachof'saidmovable spring blades having an aperture vnear itsouter end and being bendabie from an initial position 4to an actuated position upon' movement of the outer end thereof perpendicular to itsplane;l means securing together the base ends of all of said spring blades so as to form a column of said blades having their at sides substantially parallel and having the contact ends of each of said blades arranged to cooperate with the contact end of at least'one of the adjacent blades, said means including means electrically insulating each individual base end from all the other base ends; mechanism for causing all said movable spring blades to move conjointly from their initial positions to their actuated positions, and back to their initial positions, said mechanism including a slotted push bar positioned in said apertures with the edges thereof fitted into the slots on said push bar and including a key strip positioned in said apertures, and secured to said push bar, along the side of said push bar opposite to its vslotted side to retain said aperture' edges in said push bar slots; and means for causing movement of said push bar substantially perpendicularly to the planes of said spring blades so as to bend said movable-spring blades from their initial positions to their actuated positions and thereby alter the cooperation of the contact surfaces at the ends of said blades.

3. An electromagnetically actuated switching mechanism having a frame' on which is mounted, in cantilever fashion, at least one set of metallic spring blades the ends of certain of which are moved with respect to the ends of others of said spring blades, by the action of the armature oi.' said switching mechanism, to alter the electrical contact conditions at the ends 'of said blades,

characterized by the fact that said frame is provided with means for'mounting either two sets of spring-"blades side-by side above the actuating coil and parallel therewith orone-,set oi' spring blades above 'the actuating coil and parallel therewith in 'a' position between tha positions otsaid two sets of blades when two sets of blades are employed, and `by lthe' fact that.said'arma ture has two unsymmetrical armsf'independentiy bendable '-in' the di'ecti'bnsotfactuation o! said spring blades, 'one -arm actuating the spring blades-of onefset ot blades when two sets of blades are employed and actuating the spring blades of tha-single set of blades when a single set 'ofg blades-is. employed, and the other armature arm actuating only the second set of blades whenl two sets of blades are employed.

4. In a-switching mechanism; four or more metallic spring blades superposed with their at sides opposite each other in substantially parallel planes, each of said blades having a base end and a free end and having an electrical contact area near its free end for cooperation with the contact area of an adjacent blade, each of certain of said blades, not less than two, having an aperture therein near its free end, each of others of said blades having a portion of .one edge thereof near its free end in alignment with an edge of th apertures in said certain blades, and said electrical Contact areas on said blades being positioned so that they are in alignment with each other` when said edges of said other blades are in alignment with said aperture edges of said certain blades; means providing a cantilever mounting for each of said blades at its base end and insulating said blades from each other at their base ends; a guide pin temporarily insertable in said apertures to serve as a stop for said others of the blades when they are moved to bring said edges thereof in engagement with said guide pin, and thereby quickly eiect alignment of all said contact areas; and means, including mechanism operatively connected to the free end of each of said certain blades, for bending said certain spring blades and thereby effect a change in the. relative positions of the cooperating contact areas of said spring blades.

SELDEN BRADLEY SANFORD. DAVID CARL LARSON.

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