US2839628A - Electric snap action or tumbler switch - Google Patents

Description

2 Sheets-Sheet 1 Fig. 1

E. REICH ET AL ELECTRIC SNAP ACT`ION OR TUMBLER SWITCH .Win/2, rn r, w hh-1 n A.-

June l17, 1958 Filed June 21, i955 June 17, 1958 E. REICH ETAL A 2,839,628

ELECTRIC SNAP ACTION OR TUMBLER SWITCH l' Filed June 2'1, 1955 2 sheets-sheet 2 62' 6a 61 69 '[57 5656 s4 -11795v United States Patent ELECTRIC SNAP ACTION OR TUMBLER SWITCH Ern Reich, Rudolf Marton, and Fereuc Szika, Budapest, Hungary, assignors to Licencia Talalmanyokat Ertekesito Vallalat, Budapest, Hungary Application June 21, 1955, Serial No. 517,034

Claims priority, application Hungary June 26, 1954 8 Claims. (Cl. 200-67) This invention relates to electric snap action or tumbler switch assemblies of the type having stationary connection contact means and stationary connection countercontact means positioned in a mounting base and movable contact means conductively mounted on the stationary connection contact means for reversely pivotal movement between angularly spaced rest positions and adapted to contact with the stationary connection counter-contact means in at least one of the rest positions, a springloaded toggle mechanism being inserted between the movable contact means and an operating handle means and adapted to snap over the movable contact means from one of the rest positions into the other upon cockingthe operating handle means.

The known electric tumbler switches of the. above described type are aiected with various drawbacks. The structure even of the most common double-pole makeand-break switches is relatively intricate. With changeover and cross-connection switches of the double-pole type this is aggravated by the extension of space required for positioning a number of connection contacts and connection counter-contacts in the switch so that the assemblage of such switches with apparatus such as drilling machines, suction cleaners, flat irons, wireless sets is generally met with difficulties. However, constructions of less space required such as tumbler switches with movable contact means of the roller type .comprise turned components and, consequently, are expensive. With surface type switches it is their constructional height which is unfavourably extended so as to warrant a prescribed value of surface leakage path within the switch. Moreover, the assemblage of the known tumbler switches is cumbersome since their various components have to be inserted to a considerable point independently of one another so that a number of appliances is required for assembly work.

The main object of the present invention is to obviate the above said drawbacks and to provide an electric snap action or tumbler switchwhich has no turned components, is of small constructional height, consists largely of pressed parts, may readily be assembled or disassembled and in which lead-in wires are enabled to be connected directly to elastic connection contact means so as to warrant contacts of improved reliability. According to the invention, this is obtained by an arrangement in which the operating handle means is mounted, besides the conductively mounted movable contact means,y nonconductively likewise on the stationary connection contact means for reversely pivotal movement so that the stationary connection contact means, the movable contact means, the spring-loaded toggle mechanism yand the operating handle means form a constructional unit-adapted Further objects and features of the invention will be ydescribed by taking reference to the accompanying drawings which show, by way of example, two preferable em- $39,623 Patented June 17, 13555 In parment taken along the line I--l of Fig. 2.

Fig. 2 illustrates a plain view of the embodiment shown in Fig. l, partly in section.

Fig. 3 represents a cross-sectional View taken along the line III-III of Fig. 1.

Fig. 4 shows a longitudinal sectional view ofanother embodiment taken along the line IV-IV of Fig. 5.

Fig. 5 is a bottom View of the embodiment shown in Fig. 4. Finally:

Fig. 6 illustrates a cross-sectional View taken along the line VI-VI ofFig. 5.

Like reference characters denote similar parts throughout the drawings.

Referring to the drawings, the electric snap action or tumbler switch represented in Figs. l to 3 is of the surface type and comprises having a mounting base 10, stationary connection contact means 11 and stationary connection counter-contact means 12 made of elastic strip material and positioned in the mounting base 10. Movable contact means 13 are conductively mounted on the stationary connection contact means 11 for reversely pivotal movement between angularly spaced rest positions (one of which is shown inFig. l) so as to be adapted to contact with the stationary-connection counter-contact means 12 in ythe aforesaid rest positions. Between the movable contact means 13 and an operating handle means 14 a spring-loaded toggle mechanism, to be described hereinafter, is inserted so as to be adapted to snap over the movable contact means 13 from one of the above mentioned rest positions into the other upon cocking the operating handle means 14.

With the represented embodiment the toggle mechanism is formed by a U-shaped rocker means 15 made of electrically insulating material and supported by the movable contactmeans 13 which are electrically separated thereby and, lying in suitably formed grooves thereof, form a switch blade member 13, 15 therewith as is shown in Fig. 3. The -operating handle means 14 has a spring mounting means 16 for a toggle spring means 17 positioned therein which bears, by means of pins'18, against shoulders of a cavity 19 of the operating handle means 14. The toggle spring means 17 is positioned between the switch blade member 13, 15 and the operating handle means 14 on the spring mounting means 16 in a known manner so as to form an over-center mechanism 13 to 19 therewith.

In compliance with the main feature of the present invention, theoperating handle means 14 is mounted nonconductively on the stationary connection contact means 11 for reversely pivotal movement as are the conductively mounted movable contact means 13 so that, as will be seen hereinafter, the movable contact means V13, the

spring-loaded toggle mechanism 15 to 18 and the operating handle means form a constructional unit adapted to lbe mounted in and removed from the mounting base 10 as a whole.

With the represented embodiment the stationary connection contact means 11 and the movable contact means 13 are provided with perforations 2) and prongs 21 and with prongs 22, respectively, and the operating handle means 14 is provided with cavities 23, the movable contact means being mounted on the stationary connection contact means 11 by engagement of the prongs 22 of the former with the perforations 20 of therlatter, and the operating handle means 14 `being mounted on the stationary connection contact means 11 by engagement ofthe prongs 21 of the latter with the cavities 23 of the jforrner. The prongs 21 and 22 form portions of ycylindrical mantle surfaces.

Furthermore, the stationary connection contact means 11 and the stationary connection counter-contact means 12 are positioned in slots 24 and 25 of the mounting base 16 and have transversely bent ap portions 26 and 27, respectively, the mutual position of the stationary connection contact means 11 and the stationary connection counter-contact means 12 and the slots 24 and 25, respectively, being defined by xing the mounting base to a socket member 23 so as to enable the ap portions 26 and 27 iof the stationary connection contact means 11 and the stationary connection counter-contact means 12 to be sandwiched between the mounting base 1t) and the socket member 28. For this purpose the mounting base 10 is, with the represented embodiment, provided with rib portions 29 and the transversely bent flap portions 26 and 27 of the stationary connection contact means 11 and the stationary connection counter-contact means 12 are sandwiched, by means of lateral extensions (not shown) between the rib portions 29 of the mounting base 10 and the socket member 28. The ap portions 26 and 27 are provided with perforations for guiding terminal screws 32 and 33 of terminal nut-and-screw assemblies the terminal nuts of which are referred to by reference characters 34 and 35, respectively. The terminal nuts 34 and 35 lit into suitably formed cavities 36 and 37, respectively, of the socket member 28. Between the terminal screws 32 and 33 and the flap portions 26 and 27 there are inserted per se known terminal clamps 3S and 39, respectively. The mounting base 1@ is fixed to the socket member 28 by means of screws 4t? and 41.

A not represented switch cover may be xed to the mounting base 10 by means of screws adapted to engage with threaded bores 42 and 43 of conventional clamp means 44 and 45, respectively.

In assembling, the stationary connection counter-contact means 12 are positioned in the slots 25 of the mounting base 10. The movable contact means 13 and the rocker member are assembled by accommodating the former in their associated grooves in the latter so as to form a switch blade member 13, 15. The spring mounting means 16, 18 is engaged with the cavity 19 of the 4operating handle means 14, the toggle spring means 17 is mounted on the spring mounting means 16, 1S and the elements 13 to 19 are assembled so as to form an `overcenter mechanism. This is then engaged with the stationary connection contact means 11 and the assembly 11, 13 to 19 is, by means of a suitable appliance, pushed as a constructional unit into the mounting base 10 in such a manner that the stationary connection contact means 11 engage with the slots 24 and the operating handle means 14 protrudes from the mounting base lll to the desired extent.

The mounting base 1@ with the stationary connection Contact means 11, the stationary connection counter-contact means 12 and the over-center mechanism 13 to 19 is then positioned on the socket member 2S so that the transversely bent flap portions 26 and 27 of the stt.- -tionary connection contact means 11 and the stationary connection counter-contact means 12, respectively, occupy a position wherein the terminal nuts 34 and 35 engage with the cavities 36 and 37, respectively, of the socket member 28. After the screws 43 and 41 connecting the mounting base 10 with the socket member 28 have' been tightened, the rib portions 29 of the mounting base 1t) bear against the lateral extensions 30 and 31 of the stationary connection contact means 11 and the stationary connection counter-contact means 12, respectively, so that the latter are rmly xed in their predetermined positions.

In operation, upon cooking the operating handle means 14, the over-center mechanism 13 to 19-snaps over the movable contact means 13 from one of their rest positions in the other thereof as soon as the center lines ,46

and 47 of the operating handle means 14 and the switch blade member 13, 15, respectively, depart fromwtheir intermediate aligned position (which is the medial perpendicular in Fig. l)` in afmanner known per se.y

If both stationary connection contact means 11 are associated each with a pair of stationary connection countercontact means 12 (as shown in the drawings), the tumbler Works as adouble-pole change-over switch. ln this case the movable contact means 11 are adapted to contact with stationary connection counter-contact means 12 in both of their rest positions. lf, however, one stationary connection counter-contact means 12 is removed from one or both groups of stationary connection counter-contact means, only one of the rest positions will be associated with contact-making. Then the tumbler works as a double-pole make-and-break switch or as two singlepole make-and-break switches, as the case may be.

The embodiment shown in Figs. 4 to 6 diters from the previous one in that the stationary connection contact means 11 are provided with elastic xing prongs 48 and positioned in perforated slots 49 of dove-tailed crosssection of the mounting base 10, thc mutual position of the stationary connection contact means 11 and the slots 49 being xed by engagement of the xing prongs 48 of the former with the perforations 5t) of the latter. With the represented embodiment the stationary connection counter-contact means 12 are likewise provided with iixing prongs 51 and positioned in perforated slots- 52 of -the mounting base 10, the mutual position of the stationary connection counter-contact means 12 and the slots 52 being tixed by engagement `of the xing prongs 51 of the former with the perforations 53 ofthe latter.

Instead of the socket member 28, the mounting base 10 has its bottom portion closed by a cover means 54 provided with apertures 5S. The stationary connection contact means 11 have tongues 56 protruding from the mounting base 10 through the apertures 55 of the cover member 54 and the mutual position of the mounting base 10 and the cover member 54 is xed by the protruding tongues 56 being transversely bent onto the cover member 54. Obviously, the stationary connection counter-contact means 12 may likewise be provided with such tongues 56 as is suggested in the left-hand part of Fig. .6.

The stationary connection contact means 11 and the stationary connection counter-contact means 12 may have further or limiting prongs 57 and S8, respectively, protruding from the mounting base 19 through the apertures 55 of the cover member 54 and bearing against the latter so as to limit the inward displacement of the stationary connection contact means 11 and the stationary connection counter-contact means 12 when being passed through the apertures 55 of the cover member 54 into the slots 49 and 52, respectively, ofthe mounting base 10.

Moreover, the stationary connection contact means 11 and the stationary connection counter-contact means 12 have terminal extensions 59 and 60, respectively, protruding from the mounting base 10 through the apertures 55 of the cover member 54. The terminal extensions 59 and 60 represented in the right-hand portions of Figs. 4 to 6 are of the conventional souldering tag type. The terminal extensions 59 and 60 illustrated in the left-hand portions of these gures have7 however, screw-guiding perforations each with a terminal screw 61 and 62, respectively, of terminal nut-and-screw assemblies therein the terminal nuts 63 and 64, respectively, of which are guided in nut-guiding channels 65 of the cover member 54 traversed by the protruding terminal extensions 59 and 60 so as to be axially displaced upon rotation of the terminal screws 61 and 62, respectively. Obviously, such anl embodiment of the terminal extensions has the advantage that not-represented lead-in wires to be connected to the switch may easily be placed from ybelow between the protruding terminal extensions 59 and 60 and the terminal nuts 63 and 64 and ixed 'by rotating the terminal screws 61 and 62, respectively, whereupon the terminal nuts 63 and 64 become axially displaced and engaged with the lead-iny wires without necessitating rendered independent of personal skill.

in the mounting base 10, similar to that of the previous,

one. As to the cover member 54, it is placed on the mounting baseso as to closethe open bottom extremity thereof and is iixed by bending down the tongues 56 thereonto. i

With both represented embodiments, the housing or mounting base 10 of the switch is of a box-like lform having side walls and a top wall, that is being open at one extremity and having an aperture or passage 66 at the other extremity or top wall thereof to enable .the operating handle means 14 to be accommodated therein. The reversely pivotal movement of the operating handie means'14 is limited `by its striking against the wall surface of the aperture 66. Likewise, the reversely pivotal movement of the switch blade member 13, is limited by striking of the rocker member 15 against suitable wall portions 67 of the mounting base 10. In case of apparatus switches, the box-like mounting base 10 may be provided with a threaded neck portion 68 engageable with clamping nuts 69 and 70 in the conventional manner as is represented in Figs. 4 to 6.

Obviously, the inventional tumbler switch is distinguished above all by its compact structure which is obtained by the special mutual arrangement of the operating handle means 14, the movable contact means 13 and the stationary connection contact means 11. A further advantage thereof is the elimination of turned components such as rollers instead of which conventional rocker means 15 may be applied. The inventional tumbler switch is rendered inexpensive thereby and is free of the well known cracklings caused by electric discharges due to defective contact-making. Moreover, all contact means may be manufactured by punching and/ or pressing from strip materials and be positioned in the mounting base without necessitating cumbersome screw threaded clamping means which are indispensable with conventional electric tumbler switches of similar construction. Furthermore, the position of the contact meansy being thus iixed Without the use of clamping screws, there is no possibility of the reliable service of the inventional switches being impaired 'by eventual loosening of such screws. Moreover, since the cornponents of the inventional switch may be manufactured by pressing and positioned as to their best part as a constructional unit 11, 13 to 19 by means of a suitable appliance in a likewise pressed mounting base 10, the mutual position thereof is automatically warranted rather than dependent on reliable mounting operation. Thus, the quality of mounting of the inventional switches is t is likewise of importance that lead-in wires are connected directly to their associated contact means, as is illustrated in Figs. 3 and 5 where a lead-in wire 71 is connected to a stationary contact means 11 and a stationary counter-contact means 12, respectively. Thus, no undue contact resistances can arise from eventual defective mounting work as regards the inventional switch proper.

What we claim is:

1. A snap action electric switch assembly comprising a housing having side walls and a top wall, a passage in said top wall, a pair of electrically separated stationary connection contact means and at least one pair of electrically separated stationary connection counter-contact means positioned in said housing, a pair of electrically separated movable contact means each conductively mounted on one of said stationary connection contact means for reverse pivotal joint movement around a rst axis between angularly spaced rest positions and adapted torcontact with one of said stationary connection countercontact means in at leastone of said rest positions, operating handle means passed through said passage in said 6 top wall and non-conductively mounted on said pair of stationary connection contact means for reverse pivotal movement around a second axis different from said first axis, a spring-loaded toggle mechanism inserted between said pair of movable contact means and said operating handle means and adapted to snap over said pair of movable contact means from one of said rest positions into the other upon cocking said operating handle means, said pair of stationary connection contact means, said pair of movable contact means, said spring-loaded toggle mechanism, and said operating handle means lforming a constructional unit adapted to be mounted in and removed from said housing as a whole.

2. A snap action electric switch assembly comprising a housing having side walls and a top wall, avpassage'in said top wall, a pair of electrically separated stationary connection contact means and atleast lone pair of electrically separated stationary connection counter-contact means positioned in said housing, a pair of electrically separated movable contact` means each conductively mounted on one of said stationary connection contact means for reverse pivotal joint movement around a first axis between angularly spaced rest positions and adapted to contact with one of said stationary connection countercontact means in at least one of said rest positions, U- shaped rocker means made of electrical insulating inaterial and supported by said pair of movable contact means, said movable contact means being electrically separated by and forming a switch blade member with said rocker means, operating handle means extending through said passage in said top wall and non-conductively mounted on said pair of stationary connection con'- tact means for reverse pivotal movement around a second axis idihcerent from said rst axis, spring mounting means positioned in said operating handle means, toggle spring means positioned 'betweensaid switch blade member and said operating handle means on said spring mounting means so as to form an over-center mechanism therewith adapted to snap over said pair of movable contact means from one of said rest positions into the other upon cockling said operating handle means, said pair of stationary connection contact means and said over-center mechanisrn forming a constructional unit adapted to be mounted in and removed from said housing as a whole.

3. A snap action electric switch assembly comprising a housing having side walls and a top wall, a passage in said top wall, a pair of electrically separated stationary Iconnection contact means and at least 'one pair of electrically separated station-ary connection counter-contact means positioned in said housing, perforati-ons -in and prongs on said stationary connection contact means, a pair of electrically separated movable contact means, prongs on said movable contact means, said prongs of said movable contact means being engaged with said perforation's so Ias to cond-uctively mount each of said movable Vcontact means on one of said stationary connection cont-act means for reverse pivotal joint movement around a lirst axis between ian-gul'arly spaced rest positions and to enable them to contact `with one of said stationary connection counter-contact means .in at lleast one of said rest positions, U-shaped Irocker means made of insulating material and supported 'by said pair of movable contact means, said movable contact means being electric-ally separated by and forming a switch blade member with said rocker means, `operating 'handle means made of electrical insulating material and extending through said passage in sa-i-d top wall, cavities in said operating handle means, said prongs of said stationary connection contact means `being engaged with said cavities so as to non-conductively mount said operating handle means on said pair of stationary connection contact means for reverse pivotal movement yaround a second axis dilferent from s-aid first axis, ya spring-loaded toggle mechanism inserted between said pair of movable contact means and said operating handle means and adapted to snap over said pair of movable contact means from one of said rest posit-ions into the other upon cooking said operating handle means, said pair of stationary connection contact means, said pair of movable contact means, said spring-loaded toggle mechanism, and said operating handle means forming -a constructional unit adapted to be mounted in and removed from said housing as a whole.

' 4. A snap action electric switch assembly comprising a housing having side walls and a top wall, .a passage in said top wall, slot-s in said lside walls, pertorations in said slots, a pair of electrically separated stationary connection -Contact means positioned -in said slots, fixing prongs on said stationary connection contact means, the mutual position of said stationary connection 'contact means and said slots being fixed by engagement of said fixing prongs with said perforations of saids'lots', pertorations in and prongs on said stationary connection contact means, at least one pair of electrically separated stationary conne-o tion counter-contact means positioned in said housing, a pair of electrically 4separated movable contact `means, prongs on said movable contact means, said prongs oi said movable contact means being engaged with said perforations of said stationary connection contact means so as to conductively mount each of said movable contact means on one 4of said stationary connection contact means for reverse pivotal joint movement around a first axis between angularly spaced rest positions and to enable them to contact with one of said stationary connection counter-contact means in at least one of said rest positions, U-shaped rocker means made of insulating material and `supported 4by said pair of movable contact means, said movable contact means being electrically separated by and forming a switch blade member with said rocker means, operating handle means made of electrical insulating material and extending through said passage in said -top Iwal-1, cavities in said operating handle means, said prongs of said stationary contact means being engaged with said cavities so as to non-conductively mount said operating handle means `on said pair of stationary connection contact means for reverse pivotal movement around a second axis different from said iirst axis, a spring-loaded toggle mechanism inserted between said pair of movable -contact means and said operating handle means and adapted to snap over said pair of movable contact means from one of said rest positions into the other upon cooking said operating handle means, said pair of stationary connection contact means, said pair oi' movable contact means, said spring-loaded toggle mechanism, and said operating handle means forming a constructional unit a-dapted to be mounted in and removed from said housing as a whole.

5. A snap action electric switch assembly as claimed in claim 4 wherein said paii of stationary connection counter-'contact means is likewise provided with fixing prongs and positioned in perforated slots of sa-id integral housing, the mutual position of said stationary connection counter-contact means and said slots being fixed by engagement of said prongs of the former with the perf rations of the latter.

6. A snap action electric switch assembly comp-rising a box-like housing open at one extremity and having an aperture at the other extremity thereof, a'cover member for closing said open extremity of said "housing, apertures in said cover member, slots in said housing, a pair of electrically separated stationary connection contact means and at least one pair of electrically separated stationary connection Vcounter-contact means positioned in said slots, fixing mean-s for defining the mutual position yof said stationary connection contact means and said stationary connection counter-contact means, respectively, and said slots, tongues on said stationary connection contact means and said stationary connection counter-contact means protruding from said housing through said apertures of said cover member, the mutual position of said housing and said cover member being fixed by said protrudingto'ngues being transversely bent onto said cover member, a pair of electrically separated movable contact means each conductively mounted on one of said stationary connection contact means for reverse pivotal joint movement around a first axis between angularly spaced rest positions @and adapted to contact with one of said stationary connection counter-contact means in at least one of said rest Ipositions, operating handle means extending through said passage in 'said top Wall and non-conductively mounted on said pair of stationary connection contact means and accommodated in said aperture of said mounting base for reverse pivotal movement around a second axis different from said first axis, a spring-loaded toggle mechanism inserted between said pair of movable contact means and said operating handle means and adapted to snap over said pair of movable contact means from one of said rest Ipositions into the other upon cooking said operating lhandle means, said stationary connection contact means, 4said pair of movable contact means, said spring-loaded .toggle mechanism, and said operating handle means yforming a constructional unit adapted to be mounted in and removed Ifrom said housing as a whole.

7. A snap action electric switch assembly comprising a box-like housing open at one extremity and having an aperture at the other extremity thereof, a cover member for closing said open extremity of said housing, apertures in said cover member, slots in said housing, perforations in said slots, a pair of electrically separated stationary connection contact means and at least one pair of electrically separated stationary connection counter-contact means positioned in said slots, xing prongs on said stationary connection contact means and said stationary connection counter-contact means, tongues and limiting prongs on said stationary connection Contact means and said stationary connection counter-contact means protruding from said housing through said apertures of said cover member, the mutual position of said stationary connection contact means and said stationary connection counter-contact means, respectively, and said slots as well as of said housing and said cover member being fixed by engagement of said fixing prongs with said perforations of said slots and by said protruding tongues being transversely bent onto and said limiting prongs bearing against said cover member, a pair of electrically separated movable contact means for reverse pivotal joint movement around a first axis between angularly spaced rest positions and adapted to contact with said pair of stationary connection counter-contact means in at least one of said rest positions, operating handle means non-conductively mounted on said stationary con` nection contact means and accommodated in said aperture of said housing for reverse pivotal movement around a second axis different from said first axis, a springloaded toggle mechanism inserted between said pair of movable contact means and said operating handle means and adapted to snap over said pair of movable contact means from one of said rest positions into the other upon cooking said operating handle means, said pair of stationary connection contact means, said pair of movable con tact means, said spring-loaded toggle mechanism, and said operating handle means forming a constructional unit adapted to be mouted in and removed from said housing as a whole.

8. A snap action electric switch assembly comprising a box-like housing open at one extremity and having an aperture at the other extremity thereof, a cover member for closing said open extremity of said housing,` apertures and nut-guiding channels in said cover member, slots in said housing, a pair of electrically separated stationary connection contact means and at least one pair of electrically separated stationary connection countercontact means positioned in said slots, terminal extensions on said stationary connection contact means and said stationary connection counter-contact means pro-y truding from said housing through said apertures of and traversing said nut-guiding channels in said cover member, screw-guiding perforations in said terminal extensions, terminal screws in said screw-guiding perforations, terminal nuts on said terminal screws adapted to be positively guided by said nut-guiding channels so as to be axially displaced upon rotation of said terminal screws, xing means for defining the mutual position of said stationary connection contact means and said stationary connection counter-contact means, respectively, and said slots, tongues on said stationary connection contact means and said stationary connection counter-contact means protruding from said housing through said apertures of said cover member, the mutual position of said housing and said cover member being xed by said protruding,y tongues being transversely bent onto said cover member, a pair of electrically separated movable contact means conductively mounted on one of said stationary connection contact means for reverse pivotal joint movement around a first axis between angularly spaced rest positions and adapted to contact with one of said stationary connection counter-contact means in at least one of said rest positions, operating handle means non-conductively mounted on said pair of stationary connection contact means and accommodated in said aperture of said hous- 10 ing for reverse pivotal movement around a second axis diierent from said rst axis, a spring-loaded togglemechanism inserted between said pair of movable contact means and said operating handle means and adapted to snap over said pair of movable contact means from one of said rest positions into the other upon cooking said operating handle means, said pair of stationary connection contact means, said pair of movable contact means, said spring-loaded toggle mechanism, and said operating handle means forming a constructional unit adapted to be mounted in and removed from said housing as a whole.

References Cited in the le of this patent UNITED STATES PATENTS 1,739,835 Gaynor Dec. 17, 1929 2,011,293 Krieger Aug. 13, 1935 2,095,222 Wilms Oct. 5, 193,7 2,095,922 Creahan Oct. 12, 1937 2,288,283 Hutt June 30, 1942 2,430,138 Parker Nov. 4, 1947 2,531,350 Chrastina Nov. 21, 1950 2,570,281 Russell et al. Oct. 9, 1951 2,614,186 Sutton et al. Oct. 14, 1952

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