US2935580A - Snap switch - Google Patents

Description

May 3, 1960 Filed Feb. 8, 1957 J. H. JAIDINGER 2,935,580

SNAP swI'rcH 2 Sheets-Sheet 1 INVENTOR.

y 1960. J. H. JAIDINGER 2,935,580

SNAP swncu Filed 7 v 2 Sheets-Sheet 2 2 g INVENTOR. BY 2/ D 13 aka... 3% p 2 United States SNAP SWITCH John H. Jaidinger, Chicago, Ill. Application February 8, 1951, Serial No. 639,035 6 Claims. (Cl. 200-67) "pression spring confined between the opposed edge portions of the two blades in such manner that movement of one blade results in snap action movement of the other due to compression of the spring and movement of the same over center relative to the blade to be actuated. In many instances, one blade. is of generally U-shape or is provided with a window, and the other blade is disposed between the legs or within the window of the one blade. In some few instances, tension springs have been employed inswitches of the general character. While many of these proposals have found acceptance in the art, the same have been subject to a number of objectionsconcerning difliculty of manufacture, lack of consistency in operational characteristics, cost and so on.

In addition, some emphasis has been placed heretofore on mounting the compression spring for rocking move ment onthe'opposed edge portions of the two blades, allegedly to enhance the snap action movement. vIn many instances, this rocking" results in movement of the contact blade from one make position into a neutral disconnect position withoutsnapping over to. its alternate make position, which obviously is highly disadvantageous.

The object of the present invention is to provide improved snap switches of particular economy and positive consistent operation that overcome the disadvantages of the prior. proposals and satisfy the requirements of the art.

More specifically, it is an object of the invention to provide snap switchesof improved construction facilitating economical, practical and accurate manufacture of the same and affording optimum, consistent operational characteristics. a

Another object of the invention is the provision of improved snap switches embodying an independently fulcrumed contact blade and improved rigid support means defining the fulcrum.

A further object of the invention is to provide im pivotal support for the spring means of the switch, whereby the spring means is not required to rock and overcomes the, disadvantages consequent upon rocking-movement.

It is also an object ofvthe invention to provide improved snap switches embodying improved tension spring means as the operative connection between the movable blades of theswitch. I

Astill further object. of the invention is the provision of improved snap switches including one or more of the 7 features of an independently fulcrumed contact blade, a

pivotally, not rockably, supported spring means, and an improved tension spring means.

preferred embodiments of the invention.

atent Now, in order to acquaint those skilled in the art with the manner of making and using the improved snap switches of my invention, I shall describe, in connection with the accompanying drawings, preferred embodiments of my improved switch and preferred manners of making the same.

In the drawings, wherein like reference numerals indiof the switch, the view being taken substantially on line 3-3 of Figure 2;

Figure 4 is a view similar to Figure 3 showing a second species of the improved tension spring means of the invention;

Figure 5 is a view similar to Figure 3 showing a third species of my improved tension spring;

Figures 6 and 7 are views similar to Figures 1 and 2 disclosing a second embodiment of my improved snap switch, which embodiment includes a compression spring;.

proved snap switches embodying blade means defining a short distance from the stack. Adjacent the free end' thereof, each blade, atleast in a double pole, double" throw switch as herein shown, is provided with a contact 29 press fittedin an'aperture in the blade, the contact '7 beingpeenedvover to retain the same in position. The contacts 29 may be formed of any suitable electrically conductive material affording long contact life, and the blades are preferably formed of copper, in either single' or multiple ply form; While the blade portion of each of I the members 21 and 22 may have some degree of fiexiv H 0 Other objects and advantages of the invention will be-' 7 come apparent in the following detailed description of blades 23 and 25.

blades of the switch.

Referring now to the drawings, and particularly to Figures 1 to 3, l have shown a preferred embodiment of my invention as comprising a mounting stack 20,- a pair of spaced parallel stationary contact blades 21 and 22' mounted at one set of ends inthe stack, a movable actuator blade .23 mounted at one end in the stack, a fulcrum member 24 also mounted at one end in the stack, a movable contact blade 25 fulcrumed on the member 24, and a spring 26 operatively connecting the movable The stack 20 is comprised of a plurality sulating material, such as Bakelite,.between which the contact blades 21 and 22, actuator blade 23 and fulcrummember 24 are mounted, the layers of insulating material insulating. the blades 21 and 22 from one another and; the members 23 and 24. To secure the various membersin assembled relation,'tubular rivets 27, also preferably of; Bakelite or like insulating material, are employed as is, conventional. Being tubular, the rivets define boresforthe reception of bolts or the like to accommodate suitable mounting of the switch.' 1 The stationary contact blades 21 and 22 are substan tially. identical, each including a mounting portion'disposed within the stack, a transverse terminal tab 28 extending outwardly from the side of the stack, and a blade portion of reduced size extending forwardly a relatively bility, the same are substantially stationary.

out the major portion of its length, the blade 23 is pro of layers of infrom the stack and an end portion 32 joining the side members at their outer ends. The blade is quite flexible and the side members '31 thereof are preferably prestressed normally to bias the blade to a predetermined end position. The end portion32 of the blade is of a length to facilitate attachment thereto. or engagement therewith of a suitable actuating instrumentality.

The fulcrum member 24 is a prime feature of the present invention and comprises a substantially rigid metallic bar or plate of high electric conductivity. The bar is mounted at one end thereof in the stack inter mediate and parallel to the stationary blades 21 and 22 and includes a terminal tab 33 extending laterally outward to one side of the stack, preferably to the same side as that to which the tabs 28 extend. The bar may be mounted in the stack immediately adjacent the actuator blade 23, as shown, or may be spaced from the blade by one or more layers of Bakelite depending upon the de siredcharacteristics of the switch. Forwardly of the stack, the bar extends outwardly beyond the ends of the stationary contact blades and terminates intermediate the length of the actuator blade 23. This forwardly extending portion of the baror member 24 is bifurcated to define a pair of spaced parallel legs 34, whichare P eferably spaced apart by a distance corresponding to the Width of the window 30 in the blade 23. Adjacent the outer ends thereof, the legs 34 define a fulcrum 35 for the movable contact blade 25. In the embodiment shown in the Figures 1 to 5, the legs 34 are generally L-shaped as view in plan and the fulcrum 35 is formed in the surfaces of the feet of the L facing toward the stack 20. The fulcrum 35 is preferably formed as a V-shaped slot in each ofthe surfaces referred to.

The movable contact blade 25, in contrast to conventional snap switches, is not anchored in the stack 20, but is independently furcrumed on the surfaces 35 of the member 24. structurally, the blade 25 is preferably formed of copper or like conductive metal and includes a' blade portion of a width less than the spacing between the legs 34 of the member 24' and the sides 31 of the blade 23, whereby said blade portion is adapted for movement through the plane of each of the members 23 and 24. The blade portion extends inwardly from the fulcrum 35 toward the stack and into the space be tween the stationary contact blades 21 and 22. Adjacent its inner free end, the movable blade 25 carries a contact 36 extending to opposite sides thereof in alignment with the stationary contacts 29. The spacing between the contacts 29 is greater thanthe' height or thickness of the contact 36, and the blade 25 is adapted to be pivoted in opposite directions to bring the contact a' pair of laterally extending feet or tabs 37, the outer edges, i.e., the edges most outwardly from the stack 20, of which'engage in the V-shapedrslots forming the fulcrum 35. By virtue of the engaged relationship of the feet 37 in theV-shaped slots, the movable contact blade 25 of the switch is fulcrumed for pivotal movement, as opposed to rocking movement, to insure optimum operation of the same. In this position, the blade 25 is firmly retained against disassociation from the remainder of the switch, in the'longitudinal direction by means of the spring 26, thefeet on thelegs 34 and-the slots 35 in said feet, in the vertical direction by the V-shaped slots 35 and the stationary contacts 29, and in the lateral direction by the legs 34 and the tabs 37, thus to insure proper positioning of the blade at all times.

In the embodiment of the invention shown in Figures 1 to 5, a further departure from convention is the adoption of a wire tension spring for the spring means 26. The spring at its opposite ends is connected to the end portion 32 of the actuator blade 23 and to an intermediate portion of the movable contact blade 25, thus to retain the blade 25 on its fulcrum support 35. Also, the spring is preferably connected to the blade 25 as closely adjacent the contact 36 as practical to insure optimum actuation of the blade upon movement of the actuator blade 23. This relationship poses two problems, first, how to mount the spring to avoid interference with the blade 25, and second, how to complete the structure without undue or objectionable increase in the length of the switch. Obviously, a conventional coil type tension spring would not solve either problem.

According to the present invention, both of the problems above referred to are overcome in a highly convenient and economical manner by improved forms of tension spring and an improved construction of the movable contact blade. Sp'ecifically, the blade 25 is slotted longitudinally from the fulcrumed end thereof inwardly to adjacent the contact 36, as indicated at 38, and is provided in spaced relation to the end of the slot with a mounting aperture 39. The wire tension spring 26 comprises or includes a portion of a width substantially less than the width of the slot 38 adapted to be received or positioned in the slot, thus to avoid interference with the blade 25. Also, since the spring is adapted to be disposed within the slot, its effective spring lengthmay include the length of the slot as well as the longitudinal distance between the fulcrumed end of the blade 25 and the end portion 32 of' the blade 23, provided that By virtue of this design, spring width is not appreciably greater than twice the diameter of the wire from which the spring is formed, and the major portion of the distance from the bottom of the slot 38 to the end portion 32 is employed for spring length. Thus, the construction fully satisfies the requirements previously defined and affords a switch of optimum operational characteristics that is no longer than a conventional snap switch of equal capacity. To enhance spring action, the ends of the spring are provided with arcuatc hooksformed on a relatively large radius, which hooks engage respectively in the aperture 39 and in a correspondiugaperture 42 in the end portion 32 of the blade 23, whereby the spring pivots relative to the blades 23 and 25. For adjustment purposes, the end portion '32 of the blade 23 is preferably slotted in the inner region thereof to facilitate bending of a spring mounting tab portion 43 out of the plane of the blade 23, the degree of bending of the tab facilitating adjustment and calibration of the switch. The loop of the tension spring also facilitates calibration.

In addition to the loop type tension spring, the present invention affords modified spring means for performance of the functions above described. In the disclosure of Figure 4, the only structural modification over Figures 1 to 3 is the employment of a modified wire tension spring which comprises a single length of spring wire of undulating or serpentine form, as indicated at 44, the spring terminating at its ends in large diameter hooks engaged inthe apertures, 39 and 42. This. form of spring affords the advantages that its width is no greater than the the full distance from the bottom of the slot 38 to the.

end portion 32 is utilized for effective spring length.

In Figure 5, a further modified form of spring is shown which, while not affording as optimum a solution tothe above defined problems as the loop and'serpentine type springs, is entirely suitable for use in theswitch-of the invention. As shown, this spring comprises a tension coil portion 45 of a length corresponding generally to the distance between the opposed edges of the blades 23 and 25, and an elongate longitudinal end portion 46 extending to the aperture 39, the opposite ends of the spring being formed as relatively large diameter longitudinally disposed hooks for engagement in the apertures 39 and 42, respectively. This spring, in relation to those shown in Figures 3 and 4, suffers the disadvantage that effective spring length is quite severely restricted if an increase in switch length is to be avoided. However, the

spring arrangement including the elongate end portion 46 does avoid interference with movement of the blades 23 and 25. As shown in Figure 5, the coil portion 45 of the spring may extend into the space between the legs 34 of the fulcrum member 24, but in some instances it may be desirable to dispose the coil entirely within the space between the end of the member 24 and the end portion 32 of the blade 23, so as to insure against interference between the spring and other parts of the switch.

With reference to switch length, it is to be observed that the present invention, by virtue of the independent fulcruming of the blade 25, affords a substantial decrease in the length of the stationary blades 21 and 22, thus accommodating a decrease in switch length, -a substantial material saving in the length of the stationary blades, and a substantial saving inregard to the thickness of the blades 21 and 22 and the cost of the material from which the same may suitably be formed. In other words, due to the short length of the freely extending portions of the stationary contact blades, the same do .not have to be formed from thick rigid stock as was heretofore the case.

Irrespective of which modification of tension spring is employed, the above described embodiment of the present invention affords a highly economical, easily assembled,

readily calibrated switch of optimum operational characteristics. In the completed assembly, the actuator blade 23 is normally biased in an upward direction as shown in Figures 1 and 3 to 5, and its limit of upward movement is positively defined by the fulcrum member 24. In this position, the movable contact blade 25 is biased upwardly by the spring 26 to hold the contact36 in firm engagement with the contact 29 on the upper stationary contact blade 21, thus to complete a circuit from the upper terminal 28 through the blade 21, contact 29, contact 36, blade 25 and member 24 to the terminal 33. Upon actuation of the blade 23 in a downward direction,

the contact '36 is maintained in firm engagement with the upper one of the contacts 29 until the longitudinal return movement of the blade 23 in an upward direction, by virtue-of its own resiliency, the contact 36 on the blade is maintained in firm engagement with the lower contact 29 until the longitudinal centerline of the spring' 26 passes over center in the opposite or upward direction, whereupon the blade 25 is snapped back toits original position. Thus, it is to be appreciated that the switch of the present invention is positive in action and readily calibrated to perform precision switching functions in the wide variety of uses to which switches of the general character may be put.

While the switch shown in Figures 1 to 5 is of the double pole, double throw type, it is to be appreciated that this relationship may be varied as desired for particular uses.

In view of the foregoing, it is observed that the'ful-j. crum member provided according to the present 'inven tion affords the particular advantages of substantial shortening of the stationary contact blades, an independent pivotal mounting for the movable contact blade to 1 insure optimum actuation thereof, and a limit stopfor centerline of thespring 26 passes over center relative to the fulcrum 35 for the blade 25. At this time appreciable energy has been stored in the spring 26 due'to stretching thereof consequent upon anincrease inthe dimension between the end portion 32 of the blade 23 and the aperture 39. When the spring moves over cen ter, the same snaps the blade 25 rapidly in a downward direction to disengage the contact 36 from the upper one of the contacts- 29 and immediately thereafter engage the same with the lower one of the contacts 29. Due to the pivotal mounting of the spring 26 and blade 25, the blade will not hang up in an intermediate position irrespective of thespeed at which the blade 23 is moved, thus to insure positive snap actuation of 'the movable contact blade. With the contact 36 engaged with the lower contact '29, it'is obvious that the circuit from the lower terminal 28 to the terminal 33 is completed, and that the previously described circuit is' opened; Upon the actuator blade in one direction of movement thereof- In addition, the fulcrum member 24 so mounts the movable contact blade that the blade may readily be removed from the switch and replaced or repaired ifnecessary Without requiring complete disassembly of the switch.

Referring now to Figures 6 to 9, I have shown a second embodiment of the switch of my invention-employing a compression spring as the toggle linkthereof. The switch is quite similar to that disclosed in conjunction with Figures 1 to'5,'and to facilitate the description, parts similar or identical to those previously described will be indicated by reference numerals employing the same tens and digits numerals in the one hundred series. As shown in Figures 6 to 9, the switch includes a stack 120, a pair of stationary contact blades 121 and 122, an actuator blade 123 extending intermediate the blades 121 and 122 and outwardly therebeyond, a fulcrum member 124- extending intermediate the blades 121 and 1'22, 'amovable contact blade 125 fulcrumed on the member 124, and a spring 126 operativelyconnecting the blades 123 and 125 and retaining the blade 125 on its fulcrum seat on the member 124.

The stack 120 is substantially identical to the stack 20, including layers of insulating material and tubular insulator rivets 127. The stationary blades 1'21 and 122 are likewise substantially identical to those previously described, the same including terminal tabs 128 and contacts 129. The actuator blade 123 is very similarto the blade 23 including a window 130, side members 131, an: end portion 132, and an adjustable tab 143. In thepresent embodiment, however, the spring 126 is notmounted in an aperture in the tab 143,but abuts against the edge of the tab and is guidably positioned thereon bya central longitudinal reduced extensionlSll.

The fulcrum member 124','=like the member 24, includes a terminal tab 133 and a bifurcated portion extending outwardly from the stack and defining a pair a blade portion of a width less than the spacing betweenthe legs 134 of the member 124 and the side members- 131 of the blade 123, and adjacent its outer end carries a contact 136 disposed between and aligned 'with' the contacts 129. Intermediate itsends, the blade in cludes a pair of outwardly extending tabs 137, the inner edges of which, ,i.e., the edges facing toward the stack 120, are fulcrumed for pivotal movement in the V-shaped slots 135 at the ends of'the rigid legs 134. At its outer end, the blade 125 includes an adjustable tab portion 151 against the outer end of which the spring 126 is adapted to abut, the tab 151 including areduced extension 152 for centeringthe spring thereon.

a The spring ,126 preferably comprises a helically coiled compression spring, but may if desired comprise any form of compression spring conventional in the art. The spring is confined between the opposed edges of the adjustable tabs 143 and 151 in the space between the end portion 132 of the blade 123 and the outer end of the blade 125. At its opposite ends, the spring encircles the extensions 150 and 152 to be centered and retained thereby on the opposed edges of the tabs 143 and 151. In this position, the spring exerts an inwardly directed longitudinal force on the movable contact blade 125 to retain the same on its fulcrum 135. The blade is thus finmly held in position against disassociation from the remainder of the switch in all directions by the spring 126, the 'V-shape slots 135, the rigid legs 134 and the stationary contact blades 121 and 122.

The slots or fulcrum 135 support the blade 125 for pivotal movement to insure optimum actuation of the same. To mount the spring 126 at its opposite ends for pivotal movement, the present invention provides the alternative structural arrangements shown in Figures 8 and 9. With reference to Figure 8, it is to be observed that the actuator and actuated blades 123 and 125 both preferably comprise sheet metal stampings. I have discovered that if the two die pieces employed in stamping the parts are provided with what would normally be re garded as excess clearance, a narrow or thin projection is drawn out of the metal adjacent one surface thereof generally in the plane of the sheet. Such projections are indicated in Figure 8 at 153 and 155 as having been formed on the opposed edges of the blades 123 and 125, respectively, whereby the projections define knife edges against which the opposite ends of the spring 126 abut, thus to mount the spring for pivotal movement relative to the blades 123 and 125.

As an alternative arrangement, shown in Figure 9, the tab portions 143 and 151 of the blades 123 and 125 may be stamped in V-shape or inverted V-shape, the latter being shown, so as to provide at their opposed edges, substantially within the plane of the respective blade, knife edges on which the opposite ends of the spring 126 may pivot. To enhance the pivotal support of the spring, the edges of the tab portions defining the knife edges may also be provided with the projections 153 and 155, respectively, as shown.

- In all of the described forms, the spring guiding ex tensions 150 and 152 and the spring supporting knife edge projections 153 and 155 are disposed substantially in the plane of the respective blade, or at least in the plane of the tab portion thereof, to afford optimum guidance for the spring and insure proper movement of the spring and snap actuation of the movable blade.

As shown in Figure 6, the actuator blade 123 of the switch is normally biased in the upward direction, the fulcrum member 124 defining a limit stop. In this position, the spring 126 biases the tab 151 downwardly thus to maintain the movable contact 136 in firm engagement with the upper one of the stationary contacts 129. Upon movement of the end portion 132 of the actuator 1'23 in.

a downward direction, the outer end of the spring 126 is moved downwardly until the longitudinal axis of the spring passes over center relative to the plane ofthc blade 125. At this time, the spring 126 is compressed and exerts appreciable force on the blade 125 to snap the tab thereof in an upward direction. This movement results in disengagement of the contact 136 from the upper contact 129, and immediately thereafter in engagement of the contact'136 with the lower contact 129. 'Upon return movement of the actuator 123, the action generally the reverse, of that just described to move the contact 136 with a snap from the lower to the upper one of the contacts 129. Due to the pivotal mounting of the movable components of the switch, the switching action is positive and takes place rapidly, and the movable blade is not permitted to assume an intermediate position disengaged from both of the contacts 129. The two circuits selectively closed ,by the movable blade will be obvious from the precedingdescription.

As will be apparent, the embodiment of the invention shown in Figures 6 to 9 affords substantially the same advantages as the embodiment described in conjunction with Figures 1 to 5. The stationary contact blades are shortened and economically produced. The fulcrum member accommodates this reduction in size, pivotally supports the movable blade and affords a limit stop for the actuator blade. Since in this embodiment the fulcrum is provided at the outer end of the fulcrum member, the fulcrum member may be relatively short without sacrificing the length of the movable blade and space may thus be provided for the coiled compression spring 126 without increasing switch length.

In both embodiments of the invention, the movable contact blade of the switch is independently fulcrumed on the rigid supporting member for true pivotal movement, and the spring means employed is also supported for pivotal movement to insure optimum operation of the switch. The end of the movable blade carrying the contact is actuated in the same direction as the actuator is moved to simplify operation and facilitate installation of the switch for particular uses. Economical manufacture and assembly of the switch are facilitated by the structure described. In addition, the movable blade and its contact may readily be removed and replaced when desired or necessary without requiring complete disassembly of the switch. Thus, the objects and advantages of the invention have been shown herein to be attained in a convenient, economical and practical manner.

While I have described what I regard to be the preferred embodiments of my invention, it will be appreciated that various changes, rearrangements and modifications may be made therein without departing from the scope of the invention, as defined by the appended claims.

I claim:

1. In a snap switch, a mounting stack, a pair of spaced parallel stationary contact blades mounted at one set of ends in said stack, the other set of ends of said blades projecting only a short distance outwardly from said stack, a substantially planar fulcrum member mounted at one end in said stack between said stationary contact blades and projecting at its other end beyond said stationary contact blades, said member being bifurcated from inwardly of the outer ends of said stationary blades to its outer end and defining a fulcrum in the plane of said member adjacent the outer end thereof, a short movable contact blade pivoted on said fulcrum and projecting inwardly therefrom between the bifurcations of said member into the space between the said other set of ends of said stationary contact blades and proximate to said stacln'a movable actuator blade mounted at one end in said stack adjacent said fulcrum member and projecting at its other end outwardly beyond said fulcrum member, said actuator blade having a window therein coextensive withthe bifurcations of said fulcrum member and terminating in outwardly spaced relation to said movable contact blade, said movable contact blade having a pivot surface on a portion thereof spaced from said fulcrum and said actuator blade including a pivot surface on a portion thereof opposed to the said portion of said movable wntact' blade, and a spring extending between and iivotally mountedat its opposite ends on the said pivot surfaces on said movable contact blade and said actuator blade, said spring retaining said movable contact blade on said fulcrum.

2. In a snap switch, amounting stack, a pair of spaced parallel stationary contact blades mounted at one set of ends in said stack, the other set of ends of said blades at one end in said stack between said stationary contact blades and projecting at its other end beyond said stationary contact blades, said member being bifurcated from inwardly of the outer ends of said stationary blades to its outer end and defining a fulcrum in the plane of said member at the outer end thereof, a sholt movable contact blade pivoted on said fulcrum and projecting inwardly therefrom between the bifurcations of said member into the space between the said other set of ends of said stationary contact blades and proximate to said stack, a movable actuator blade mounted at one end in said stack adjacent said fulcrum member and projecting at its other end outwardly beyond said fulcrum member, said movable contact blade includinga portion projecting outwardly from said fulcrum toward the outer end of said actuator blade, said actuator blade having a window therein coextensive with the bifurcations of said fulcrum member and terminating in outwardly spaced relation to said portion of saidmovable contact blade, said movable contact blade having a pivot surface on the outer edge of said portion thereof and said actuator blade including a pivot surface on the edge portion thereof opposed to the said portion of said movable contact blade, and a compression spring extending between and pivotally mounted at its opposite ends on the said pivot surfaces on said movable contact blade and said actuator blade, said spring retaining said movable contact blade on said fulcrum.

3. In a snap switch having actuator and actuated blades including movable end portions, the improvement comprising a generally planar fulcrum member including a pair of spaced legs defining a fulcrum in the plane thereof, one of said blades being pivotally mounted at one end thereof on said fulcrum, said one blade being narrow and extending between the legs of said member, the other of said blades having its movable end disposed closely adjacent said fulcrum and to the side thereof opposite said one blade, said one blade being slotted longitudinally thereof from said one end to adjacent its movable end, and a wire tension spring extending through the slot in said one blade and between said legs of said fulcrum member and being connected at its ends to the movable end portions of the two blades, said spring throughout the length thereof extending through said slot being of a Width not greater than twice the diameterof the wire, said slotted blade, said spring and said fulcrum member facilitating provision of a readily calibrated, positive action snap switch of minimum length, width and depth having a relatively long spring and relatively short blades.

4. In a snap switch, a mounting stack, a pair of spaced parallel stationary contact blades mounted at one set of ends in said stack, the other set of ends of said blades projecting only a short distance outwardly from said stack, a generally planar fulcrum member mounted at one end in said stack and projecting at its other end outwardly beyond said stationary contact blades, said member from adjacent said stacks to its outer end including a pair of spaced legs, said legs at their outer ends including inwardly directed'projections defining fulcrum surfaces opposed to said stack in the plane of said member, a short narrow movable contact blade pivoted at one end on said fulcrum surfaces, said movable contact blade being slotted from said one end thereof to adjacent the other end thereof and at its one end includ ing tabs to opposite sides of the slot therein engaging on said surfaces, said movable contact blade projecting inwardly from said fulcrum surfaces between the legs of said fulcrum member and into the space between the and a wire tension spring disposed in the slot in said movable contact blade and extending between the legs of said fulcrum member, said tension spring being-connected at its inner end to said other end portion of said movable contact blade and at its outer end to said actuator blade, said spring retaining said movable contact blade on said fulcrum surfaces and throughout the length thereof disposed within said slot and between the legs of said fulcrum member being of a width no greater than twice the diameter of the wire, said movable contact blade by virtue of disposition of said spring in the slot therein accommodating a short actuator blade and, despite the said other set of ends of said stationary contact blades shortness of the blades, having a relatively long effective lever arm and accommodating a relatively long spring to assure accurate calibration and positive, action of the switch, said fulcrum member, movable contact blade and spring facilitating formation of the switch to minimum dimensions as to length, width, and depth;

5. In a snap switch having a stack, a pair of spaced parallel stationary'contact blades mounted at one setof ends in said stack and an actuator blade mounted at one end in said stack and extending outwardly beyond the free ends of the stationary blades, the improvement comprising a fulcrum member mounted at one end in said stack and extending at its 'free end beyond the free ends of the stationary blades but terminating short of the free end of said actuator blade, said member being bifurcated and the bifurcations thereof defining a fulcrum in the plane of said member adjacent the outer end thereof, a movable contact blade seated on said fulcrum, said movable contact blade being narrow and extending inwardly from said fulcrum between the bifurcations of said member into the space between the free end portions of the stationary blades, the actuator blade includ ing a free end portion disposed outwardly of and opposed to the outer end of said movable contact blade, and a spring engaging at its opposite ends said end portion of the actuator blade and said movable contact blade, said spring retaining said movable contact blade on said ful- V crum.

6. In a snap switch having a stack, a pair of spaced parallel stationary contact blades mounted at one set of ends in said stack and an actuator blade mounted at one end in said stack and extending outwardly beyond the free ends of the stationary blades, the improvement comprising a fulcrum member mounted at one end in said stack and extending at its free end beyond the free ends of the stationary blades but terminating short of the free end of said actuator blade, said member being bifurcated and the bifurcations thereof defining a fulcrum in the plane of said member at the outer end thereof facing in the direction away from the stack, a movable contact blade seated on said fulcrum, said movable contact blade being narrow and extending inwardly from said fulcrum between the bifurcations of said member into the space between the free end portions of the stationary blades, the actuator blade including a free end portion disposed outwardly of and opposed to the outer end of said movable contact blade, and a compression spring disposed between and engaging at its opposite ends against the opposed edge portions of the actuator blade and said movable contact blade, said spring retaining said movable contact blade on said fulcrum.

References Cited in the file of this patent UNITED STATES PATENTS 2,487,374 Riche Nov. 8, 1949 2,508,040 Ransome May 16, 1950 2,551,714 Stoeser May 8, 1951 2,565,790 Ryan Aug. 28, 1951 2,758,171 Cherry Aug. 7, 1956 2,788,409 Grover Apr. 9, 1957 FOREIGN PATENTS 648,682 Great Britain Jan- 10,

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