US2357973A - Liquid-tight electric switch - Google Patents

Description

Sept. 12, 1944. c; F. ROBBINS LIQUID-TIGHT ELECTRIC SWITCH Filed Aug. 18, 1942 2 Sheets-Sheet l Patented Sept. 12, 1944 LIQUID-TIGHT ELECTRIC Clyde F. Robbins, Milwaukee, Wis., assignor to Cutler-Hammer, Inc., Milwaukee, Win, a cor= 9 Clai.

This invention relates to improvements in liquid-tight electric switches, and the invention relates more particularly to means for rendering substantially oil-tight manually operable switches of the reciprocating contactor type.

A primary object of the invention is to improve and simplify the construction, assembly and operation of the elements which provide oil-tightness of switches of the aforementioned character.

Another'obiect is to minimize the eflect upon the operating characteristics of such a switch of the added element or elements aiiording tightness.

Another object is to provide oil-tight switches of either the so-called one-hole mounting type or the flush-plate type.

Another object is to provide for use of simple additional or substitute elements to render switches of a known form' substantially oil-tight.

Another object is to provide for concealment of the elements which render such switches oil-=- tight, whereby the external dimensions and the attractive appearance of the latter is unafiected.

Another object is to provide for attainment oi the advantage of oil-tightness in switches of the reciprocating contactor type without sacriiicing any of the functional or operative advantaxes of the latter.

Another and more specific object is to provide means for rendering substantially oil-tight such reciprocating contactor switches of the rotary selector type.

'Another object is to provide novelmeans for rendering substantially oil-tight a reciprocating contactor switch adapted for flush-plate mounting.

Another object is to provide novel and simple means for mounting such substantially oil-tight switches.

Another object isto provide novel forms oi diaphragms of molded rubber or a rubber-like material to render switches of the reciprocating contactor type substantially oil-tight.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate certain embodiments of the invention which will now be described, it being understood that the embodiments illustrated are susceptible of modification in respect of certain structural details thereof within the scope of theappended claims.

In the drawings,

Figure 1 is a view, partly in vertical section and partly in side elevation, of a pushbutton switch of the one-hole mounting type having my improved elements associated therewith to render the same substantially oil-tight, the panel, to which the switch is attached as a unit,

' being shown in section.

Fig. 2 is a bottom plan view of the pushbutton shown in Fig. 1.

Fig. 3 is a side elevational view of the diaphragm shown in Fig. 1, the same being molded 'to the form illustrated from rubber or a rubberlike material.

Fig. 4 is a fragmentary vertical sectional view of a rotary selector switch of the reciprocating contactor type having my improved elements associated therewith to render the same substantially oil-tight.

Fig. 5 is a. perspective view of the diaphragm shown in Fig. 4, the same being molded from rubber or a rubber-like material. 7

Fig. 6 is a fragmentary side elevational view of a one-hole mounting type of reciprocating contactcr switch having a mushroom head operator, the supporting panel and the gasket of rubber or rubber-like material, which assists in rendering the switch substantiallyoibtight, being shown in section.

Fig. '7 is a, fragmentary side elevational view oi. a flush-plate mounting type of reciprocating contactor switch having a. mushroom head operator, the fiush plate, the metal guide and stop plate, and the Li -plate gasket of rubber or rubher=liire mat e/(Ion h Ling shown in section.

s is a fragrner sectional view of a ans-mole mounted, reciprocating contactor switch off the pushbutton type shown in Fig. 1, but showing the same supported upon a flushplate having a gasket of rubber 017 rubber-like material interposed between the same and a supporting panel; portions of the elements in Fig. 8 being shown in elevation, and

Fig. 9 is a fragmentary view, partly in sec tion and partly in elevation, of a one-hole mounted, reciprocating contactor switch of the rotary selector type shown in Fig. 4, but showing the same supported upon a flush-plate as in Fig. 8.

Referring first to that form or my invention shown in Figs. 1 to 3, the numeral Ill (Fig. 1) designates a one-piece molded insulating base of the character disclosed in my application, Serial No. 449,756, filed July 4, 1942, for Electricswitches. Base it and the switch parts associated therewith, including plunger 5 l, bridging contactors i2 carried by the latter, and the combined stationary contact and terminal members l3 and i l carried by base l0, may be identical with corresponding elements of the switches shown in said application, Serial No. 449.756, and are adapted to perform corresponding functions. As disclosed in said application, Serial No. 449,756, base it may have attached thereto from one pair up to four pairs of said stationary contacts, and from one to four bridging contactors for-cooperation with the pair or pairs of contacts. Plunger i2 is spring biased outwardly from the recess in base iii, the degree of outward movement thereof being limited by engagement of one or more of the bridging contactors with an upper pair or pairs of stationary contacts (or by engagement said contactors with dummy contact elements), as described in said application, Serial No. 449,756.

The die-cast metal adapter member i5 may be identical With'that designated by numeral 60 in the device or Fig. of said application, Serial No. 449,758, member It being provided with a central, circular opening having a screw threaded upper end portion it to receive the externally screw threaded shank portion it (Fig. l) oi a hollow metal bushing, the enlarged head of which is designated by numeral i5. Head I6 is preferably vertically milled or otherwise roughened peripherally to facilitate turning or tightening thereof (as'shown at 6! in Fig. 13 of said application, Serial No. 449,256). Head I6 is provided with a downwardly lacing annular clamping shoulder ili whichis adapted to overlie the outer face or supporting panel or cover member II, which is shown as composed of metal. Panel ll is provided with. a circular onening ll to provide panel ll, plate it having an opening E3 to ac commodate the bushing shanh'and said plate is preferably provided with an integral lug (not shown, but corresponding to lug 84 in Fig. 13

of said application, Serial No. 449,756) panel I'l having at least one suitably shaped opening (not shown) to accommodate said lug, which is likewise adapted to fit into any one or tour recesses provided at the upper surface of adapter l5. Two of said recesses consist of the countersinks W, i5 opening to the upper surface of adapter l5; whereas another diametrically opposed pair of recesses (not shown) is positioned at right angles to the respective countersinks i5 and i5 The opening or openings in panel ll to accommodate the lug on plate it will therefore be drilled or punched at any one or more of four points spaced ninety degrees apart; the lug cooperating with thewall of said opening to insure against rotary or angular displacement of plate It.

The portion (not shovm) oi plate it having the desired legend applied thereto may therefore be positioned at any one of four different angles,

depending upon the position in which the panel ll is to be mounted, and the desired rotary po=- sition or the switch relatively to the panel. Mem her iii is provided with tapped passages l5 and l8 which open to the respective countersinks i5 and iii, said passages being adapted to receive portion 22'.

diametrically opposed end notches to accommodate the screw shanks I9, [9, and a relatively large central circular opening 20. Thus the plate 20 is quite similar to the plate 48 in Fig. 9 of said application, Serial No. 449,758, except that the opening 2|! is of substantially larger diam- 1 eter than the opening 48'' in plate 48.

The lower end of the central opening through adapter I5 is in the form of a relatively large downwardly opening countersink or annular recess IS, the upper end wall I! of which forms an annular shoulder which is adapted to overlie the outwardly extending annular flange 2| of a punched and stamped sheet metal cup washer 2|. The material of cup washer 2| extends downwardly from flange 2 I, as shown at 2 l and then inwardly, as shown at 2I; the inwardly extending portion 2Iterminating in the peripheral wall 2| of a circular opening, as shown.

The means for rendering the switch mechanism oil-tight preferably comprises a diaphragm 22, which is molded to the form illustrated in Figs. 1 and 3 from high quality flexible rubber or a rubber-like material. Preferably the diaphragm consists of the synthetic rubber or rubher-like material which is sold commercially under the trade name of Neoprene. Such material is characterized by its high degree of tie):- ibility, toughness, long life, resistance to hardening and cracking when in use, and especially by its resistance to deterioration or disintegration in the presence of oil, grease or other similar substances, which render the life of articles composed of ordinary or natural rubber relatively short.

Member 22 comprises an intermediate portion- 22' in the form of a frustrum of a cone, the flat, circular upper end wall 22 of which is provided with a relatively small circular opening 22" (Fig. 1) to accommodate the shank of a screw 23, as hereinafter described. Member 22 is in the form of a relatively thin web or diaphragm, and as shown said web is reflexed at 22 to provide the upwardly and outwardly extending annular Portion 22 is provided adjacent its upper end 22 (see Fig. 3) with a laterally extending annular bead or enlargement; 22'. As

the threaded end portions l9", l9 of a pair of shown in Fig. 1 end 22 and bead 22 arepositioned within the countersink Ii in adapter I I, for compression-or clamping thereof between cup washer 2| and plate 20, as an incident to tightening of screws [9.

However, prior to such assembly of diaphragm 22 with respect to adapter I! and switch base ill a molded insulating pushbutton 24 is attached to the diaphragm. Thus pushbutton 24 is preferably provided with a central cylindrical stud 24 whose fiat lower end 24* (Fig; 3) is offset upwardly from the lower edge 24 of the periphery or skirt portion 24* of the pushbutton. Stud 24' is provided with a downwardly opening recess 2 3 which is topped or otherwise threaded to accommodate the shank of screw 23. A metal washer 2! is preferably interposed between the head of screw 23 and the upper end wall 22 of diaphragm 22 to insure proper clamping or said end wall against substantially the entire end surface 24* of stud 24. from the lower edge 2" o! the pushbutton are a plurality of integral struts or fillets 24, 24, 24 cavities or recesses 24, 24 24' being provided therebetween. 'In' this manner pushbutton 24 is made relatively light, while insuring adequate strength thereof. As shown in Fig. 1, the arrangement is pref- Further oil'set upwardly erably such that upon assembly of the aforementioned parts, the fiat upper end of the extension of plunger I i will underlie and engage the head of screw 23 to bias the pushbutton 24 to its normal upper position, as an incident to movement of plunger Ii and its associated contactors to their normal upper positions under the bias of said plunger as aforedescribed. From the foregoing description it will be ap parent that any oil or other liquid which may enter between the periphery of pushbutton 2d and the surrounding wall 01" the opening in bushing it will be eifectively trapped or stopped from entering the switch chamber, by reason of the presence of diaphragm 22. g

In Order to prevent the possibility of oil or other liquid entering the opening I'l in panel I l, and thence passing exteriorly over adapter member l5 and base toward the switch con tacts and contactors, I prefer to provide an an nular washer or gasket 26 which is interposed between the upper end portion of adapter 65 and the lower surface 01' panel ll. Gasket it is preferably punched from a sheet of synthetic rubber or rubber-like material, such as Neoprene."

As will be apparent, upon manual depression oi pushbutton 24 against the bias of plunger ii the diaphragm 22 will bend or reflex annularly to readily accommodate the downward movement of the pushbutton, the amount of energy required to flex diaphragm 22 being relatively small or negligible, as compared with that required to overcome the bias of plunger H. The means for rendering the switch mechanism oil-tight thus has comparatively little eflfect upon the operating characteristics of the switch, so that most of the switch parts (including the plungerbiasing spring) may be identical with those of ordinary pushbutton switches of the ,present character.

As will be apparent to those skilled in the art, the panel 11, if serving as a closure for a housing. may have a gasket of the aforedescribed rubber or rubber-like material underlying the peripheral portion thereof (not shown) to more completely insure oil-tightness of the switch mechanism or mechanisms associated therewith. Figs. 1 to 3, inclusive. have been drawn to one an one-half times normal scale.

The modification illustrated inFigs. 4 and 5 may embody most of the elements oi the switch of Figs. 1 to 3, and also, therefore, many of the elements disclosed in my aforementioned application, Serial No. 449,756. The elements in Fig. 4 corresponding to those of Fi 1 have been given like numerals of reference. However, Fig. 4 discloses a rotary selector switch (which may be either the two-position type or threeposition type disclosed in my prior application filed July 18. 1942, Serial No. 451,417, for Selector swiwhes) having my improved means associated therewith to render the same substantially oil-tight.

Thus. with reference to Fig. 4, it is to be under stood that the selector switch will be of either the two-position type or three-position type, depending upon the formation of the groups of cam surfaces (not shown) at the lower edge of the rotary actuating member 21 of molded insulating material. as disclosed in said application, Serial No. 451.417. Member 21, which is prefenably composed of "Bakelite, is adapted to tele-= scopically fit onto the upper end of a cap member 28 molded from like or similar material. Cap

28, in turn, is recessed to fit onto the laterallyv notched upper end portion ll of projection of plunger ii, a spring ring it being Iorced or snapped onto said reduced end it, whereby a frictional connection between plunger H and cap 28 is provided. The diametrically opposed sets of downwardly facing cam surfaces upon member 2? are adapted for cooperation with the diametrically opposed laterally extending lugs 28 and 28 upon cap 28) to effect or permit move merit of plunger ii in opposite directions respec= tively.

As disclosed in said application, Serial No. 451,417, member N is provided at its lower end with diametrically opposed laterally extending lugs (not shown) of segmental form. Saidlugs are adapted to underlie the annular fiat portion 3a of a punched and stamped sheet metal mem; her, said portion at being adapted to seat against the upper or end wail of countersink i 5, to thereby limit the degree oi upward displacement of member 2?. Portion 3b is provided with an in tegral upstanding lug (not shown) at a predator mined point in the periphery thereof, which lug is adapted to fit within one of a plurality oi notches (not shown) in said end wall of countersink 85, whereby rotary displacement of portion so is prevented. Also formed integrally with portion 89 are a pair of diametrically opposed downwardly extending lugs 3t and 39' which jointly cooperate with the lugs upon member 21 to limit the degree of rotation of the latter in each di rection.

A cup washer 26, like that oi Fig. 1, is posi= tioned within countersink l5 to underlie portion at and lugs 30 and ell". Due to the presence of the ap 28 in the device of Fig. 4 the diaphragm ill, which assists in rendering the switch oiltight, is provided with a central portion di of substantially frusto conical form; but oi' sub-= stantialiy less height than the corresponding portion 22 oi diaphragm 22 (Figs. 1 and 3). Portion is'provided with an opening 3i (Fig; 5)

"did

oi polygonal contour to closely fit around the projection ll of plunger ll, said portion hi being oi increased 'ilhlfilii.,.-il3$ around opening iii" to provide a flange 3i having a flat upper surface ai which is adapted to be engaged by the flat lower face of cap member 28, when the parts are assembled as shown in Fig. 4.

A split spring ring underlies the flange 35 and surrounds the oi opening ill to insure a close fit of the We X5 thereof around said pro jec ion ii of the plunger. In practice the split ring 32 may be positioned upon the neck portion oi diaphragm ill and. the latter then pressed downwardly onto projection l l of the plunger; or the ring may be forcibly spread to provide for proper positioning thereof after sliding of said d aphragm onto projection ii. The portions 35 ill and Si of diaphragm at are substanflally like the corresponding portions 22, 22? and 22 of diaphragm the diaphragm 30 being bent or refiexed at'iil substantially as shown at 22 on diaphragm 22 (Figs. 1 and 3).

it is to be understood that'diaphragm 88 is preferably" composed of the same material as the diaphragm llaforedescribed. The gasket 26 of is interposed between the upper end port r of adapter and the lower face of panel 6 to perform the same function as in the device of Fig. 1. Portions 3i and iii are clamped between the peripheral flange of cup washer 2i and the outer surface of plate 2d upon tightening of screws id, as described in connection with Fig. 1.

The manner in which the diaphragm ill and gashat 2% act to provide oil-tightness oi the switch is believed. to be obvious from the description of Fig. 1.

In Fig. 6 I have shown a one-hole mounted switch having a mushroom head type of operator, the base it, adapter i5 and supporting panel being identical with the correspondingly designated parts of Figs. 1 and 4. Thus, as disclosed in said application, Serial No. 449,756, the mushroom head operating member 33 and the bushing 34' (whose threaded lower end 34 cooperatively engages the threaded opening in adapter I5) are so formed and so related to each other as to provide a substantial degree of oil-tightness thereof, at least as regards splashed, sprayed or dripping oil imringing thereon, it being understood that a switch like that of Fig. 6 is usually mounted for movement oi. the rod or shaft oi the mushroom head in a horizontal plane, instead of the vertical mounting thereof indicated inthe drawings. Accordingly, it is only necessary to additionally insure against ingress oil par ticles to the switch parts through the opening l'l' in panel i7; and for this purpose I provide a gasket 35 oi Neoprene, or a similar rubber-like material, which is adapted to be clamped between the upper end or adapter 15 and the inner face of panel H as an incident totlghtening 0! bushing 3%. As shown a metal washer of suitable thickness, or a plurality of metal washers 36 and 37 of different thicknesses may be interposed between the head or bushing 34 and the outer face of panel 57].

A plate 38 which acts as a guide for the proiection li of the plunger and as a stop for the lower end portion of the shaft of the mushroom head operator 33 is interposed between the lower surface of adapter i5 (Fig. 6) and the upper end oi base iii, said plate being also shown in section in Fig. 7, hereof, and a like plate being employed in the devices of Figs: l6, l7 and id of said ap-= plication, Serial No. 449,756, and designated there by the numeral l3.

The mushroom head operated switch of Fig. 7 is quite similar to that of Fig. 6, but differs from the latter in that the switch base IV-with its associated parts is attached by the pair ofscrews 19 to a die cast metal flush plate 38. Flush-plate 39 is quite similar to that designated by numeral.

83 in Figs. 20 and 21 of said application, Serial No. 449,756, but differs therefrom in respect of the provision of a plurality of bolt openings or passages along each of the four sides thereof, the intermediate openings in two of the sides a:

flush plate 39 being shown at 39 and 39 in Fig 7; and flush plate 38 further differs in respectoi the provision of an opening or relatively large diameter which is threaded, as indicated at 38, for cooperation with the threaded shank 34 of bushing t l. r

A gasket he is interposed between the flat lower iace or flange portion of flush plate 39 and the upper surface of a panel 4|, said gasket'having openings to provide clearance for the shanks oi screws M, and panel M having tapped openings to accommodate said shanks. In practice the gasket 40 extends outwardly to a flush relationship to the periphery of flush plate 39 and inwardly to a flush relationship to the relatively large rectangular opening 4| in panel 4!. The gasket 40 therefore cooperates with the other elements to render the switch of Fig. 7 substantially oil-tight. v

In Fig. 8 I have shown an oii tight pushbutton switch substantially like that shown in Figs. 1

to 3, but with a flush plate mounting substantially like that shown in Fig. 7. The parts of the device of Fig. 8 corresponding to the parts of Figs. 1 and 7 have been given like numerals of reference. The manner in which the diaphragm 22 and gasket 40 act to render the switch of Fig. 8 substantially oil-tight are believed to be obvious from the descriptions of Figs. 1 and 7. As shown in Fig. 8, however, a relatively thick washer 43 is interposed between the head it of the bushing and the upper suriiace of flush plate 39-to insure against possible interference between the lower end of the bushing shank l8 and the cup washer 2|.

In Fig. 9 I have shown an oil-tight rotary selector switch substantially like that shown in Fig. 4, but with a flush plate mounting substantially like that of Figs. 7 and 8. The parts of the device of Fig. 9 corresponding to the parts of Figs. 4, 7 and 8 have been given like numerals of reference. The manner in which the diaphragm 3| and gasket 40 of Fig. 9 act to render the switch of Fig. 9 substantially oil-tight are believed to be obvious from the descriptions of Figs. 4, 7 and 8. As shown in Fig. 9, however, a metal collar or tube section 44 is adapted to be interposed between the head I8 01' the bushing and a flat, annular plate 45 which is provided with suitable legends (not shown) for cooperation with a line or mark (see 21, Fig. 4) upon member 21 to indicate the condition of the controlled circult or circuits. Collar 44, as shown, serves to conceal that portion of the threaded shank I8- 01' the bushing which would otherwise be exposed. Indicating plate 45 is preferably attached to flush plate 39, as by means of a pair of drive screws 46, which take into suitable recesses drilled in the upper surface or said flush plate, as will be readily understood by those skilled in the art.

As will be understood by those skilled in the art, although the diaphragms Hand 3| are preterably molded to the forms thereof shown in the drawings, they may be molded to frusto-conical form throughout the height of each or the same, with the respective beads M and 3| thereof located upon the interiors thereof; the lower ends thereof being thereafter turned inside out to provide the forms illustrated and to position said beads exteriorly thereof. Although the beads 22 and 3| i'orm the major portion of the material to be clamped between .cup washer 2| and plate 20, it will be apparent from Figs. 1, 4,

8 and 9 that the end portions M -and ii of the 1 diaphragms are likewise compressed or deformed during the clamping operation to assist in providing the oil-tight connection between the peripheries of the diaphragms and the respective adapter members l5.

Although I have herein disclosed the use of j diaphragms of substantially irusto-conical form, it is to be understood that if desired I may employ a diaphragm in the form of a bellows having a plurality of convolutlons or corrugations. Similarly, although I have specifically described the diaphragms .as composed of Neoprene or a similar flexible, rubber-like material, it is obvious that I may employ less flexible materials, such, for instance, as rubber or a rubber-like ma terial reinforced by a fabric or cloth, or a fabric or cloth impregnated or otherwise treated with an oil-resistant and/or water-resistant material. such as varnish or a cellulosic material.

I claim:

1. A. substantially liquid-tight switch of the re ciprocating contactor type, comprising a molded insulating base having a recess opening to one end thereof, a contactor-carrying plunger slidable within said recess and spring-biased outwardly therefrom, contacts carried by said base into and out of bridging engagement with which said contactor is adapted to move, an adapter member rigidly secured to the recessed end of said base, a diaphragm of flexible, liquid-tight material having a peripheral portion thereof clamped between said adapter and said recessed end of the base, said diaphragm having a central portion surrounding an outer end portion of said plunger and clamped in a given position relatively to the latter to provide for liquid-tightness of said central portion, the web of said diaphragm between said peripheral and central portions being of greater length than the distance therebctween and the same being reflexd upon itself to provide an annular trough of approximately V-form in transverse cross section, the excess length of said web being adapted to provide for movement of said plunger from its normal outer extreme position to it inner extreme position without stretching of the material of said diaphragm, whereby the manual operating force required to effect inward movement of .said plunger is substantially unaffected by said diaphragm, said adapter member having a central opening therethrough to accommodate a manual operating member associated with said plunger,

and said diaphragm serving to stop or trap oil entering said opening against passage into the recess of said base.

2. A substantially oil-tight switch of the reciprocating contactor type, comprising a molded insulating base having a recess opening to one end thereof, a contactor-carrying plunger slidable within said recess and spring-biased outwardly therefrom, contacts carried by said .base into and out of bridging engagement with which. said contactor is adapted to move, an adapter member rigidly secured to the recessed end of said base, a molded diaphragm of resilient, rubberlike material having a peripheral portion thereof clamped between said adapter and said recessed end of the base, said diaphragm having a central portion surrounding an outer end portion of said plunger and clamped in a given position relatively to the latter to provide for oil-tightness of said central portion, the web of said diaphragm between said peripheral and central portions being of greater length than the distance therebetween and the same being refiexed upon itself to provide an outwardly opening annular trough of approximately V-form in transverse cross section, the excess length of said web being adapted to provide for movement of said plunger from its normal outer extreme position to its inner extreme position without stretching of the material of said diaphragm, whereby the manual operating force required to effect inward movement of said plunger is substantially unaffected by said diaphragm, said adapter member having a central opening therethrough to accommodate a manual operating member associated with said plunger, said diaphragm serving to stop or trap oil entering said opening against passage into the recess of said base, the peripheral wall of said adapter opening having a screw-thread formed thereon,a hollow metal bushin having an enlarged head forming an inwardly facing c1amping shoulder and a reduced shank externally threaded for cooperation with the screw-thread aforementioned, said shoulder being adapted to overlie the outer face of a suitably perforated panel and said adapter member being adapted to underlie the inner face of said panel, and a gasket of resilient, rubber-like material interposed between said inner face or the panel and said adapter to insure against passage of oil from the panel opening to the exterior of said adapter and the perforation in the latter, a hollow metal bushin having a head adapted to seat against the outer surface of said panel and an externally threaded shank adapted to engage said threaded opening toprovide for one-hole mounting of said adapter, a pushbutton reciprocable within said central opening, a flexible diaphragm of resilient, rubber-like material molded to substantially frusto-conical form, the flat upper end of said diaphragm having a relatively small opening formed therein, a screw the shank of which penetrates said opening and takes into a tapped recess in the lower end of said pushbutton, the head of said screw clamping said upper end into oiltight engagement with said pushbutton, said diaphragm being reflexed upwardly upon itself to provide an annular web portion of substantially V-shape in transverse cross section, the outer end of the reflexed portion of said diaphragm having an annular bead'formed integrally therewith, said adapter being recessed at its inner end to accommodate said bead, a recessed molded insulating base underlying said adapter, and means associated with said base to clamp said bead in oil-tight relation to said base and said adapter as an incident to securement of said base and adapter to each other.

4. A pushbutton operated switch of the reciprocating contactor type adapted for one-hole mounting upon a perforated panel or the like, said switch including an adapter member having a threaded central opening therethrough, the outer end of said adapter being arranged to seat against th inner surface of said panel around the perforation in the latter, a hollow metal bushing having a head adapted to seat against the outer surface of said panel and an externally threaded shank adapted to engage said threaded opening to provide for one-hole mounting of said adapter, a pushbutton reciprocable within said central opening, a flexible diaphragm of resilient,

rubber-like material molded to substantially frusto-conical form, the flat upper end of said diaphragm having a relatively small opening formed therein, a screw the shank of which penetrates said opening and takes into a tapped recess in the lower end of said pushbutton, the head of said screw clamping said upper end into oil-tight engagement with said pushbutton, said diaphragm being reflexed upwardly upon itself to provide an annular web portion of substantially V-shape in transverse cross section, the outer end of the reflexed portion of said diaphragm having an annular bead formed integrally therewith, said adapter being recessed at its inner end to accommodate said bead, a recessed molded insulating base underlying said adapter, means associated with said base to clamp said bead in oil- I tight relation to said base and said adapter as an incident to securement of said base and adapter electric switch of the said switch including a recessed molded insulating base, a cast metal flush plate to the inner surface of which said base is rigidly secured, said flush plate having a relatively large screw-threaded opening formed therein;-a hollow metal bushing having a head portion overlying said flush plate and a shank portion having threaded engagement with said opening, a switch operating element positioned within said bushing and accessible from the exterior thereof, said flush plate having an annular recess formed in the/lower surface there'- of, a diaphragm composed of flexible, rubber-like material having its peripheral edge portion posl-" tioned within said annular recess and clamped therein as an incident to rigid securement of said base to said flush plate, the central portion of said diaphragm having means associated therewith to provide for oil-tight connection thereof to a reciprocating part of the switch, and said diaphragm including a refiexed web portion between said peripheral and central portions to provide for movement of said central portion throughout its totalfange without requiring any substantial degree of stretching of said web portion.

6. In combination, an electric switch of the reciprocating contactor type, said switch including a recessed molded insulating base, a cast metal flush plate to the inner surface of which said base is rigidly secured, said flush plate having a relatively large screw-threaded opening formed therein, a hollow metal bushing having a head portion overlying said flush plate and a shank portion having threaded engagement with said opening, a switch operating element positioned within said bushing and accessible from the exterior thereof, said flush plate having an annular recess formed in the lower surface thereof, a diaphragm composed of Neoprene, said diaphragm having its peripheral edge portion positioned Within said annular recess and clamped therein as an incident to rigid securement of said base to said flush plate, the central portion of said diaphragm having means associated therewith to provide for oil-tight connection thereof to a reciprocating part of the switch, said diaphragm including a refiexed web portion between said peripheral and central portions to provide for movement of said central portion throughout its total range without requiring any degree of stretching of said web portion, a perforated panel to which said flush plate is rigidly but removably secured, and means including a gasket of Neoprene interposed between said flush plate and said panel to assist in rendering said switch substantially oil-tight.

7. In an electric switch of the reciprocating contactor type, in combination, a recessed molded insulating base, a contactor-carrying plunger slidable within said recess, a die-cast metal member to which said insulating base is rigidly secured, a perforated panel affording a support for said metal member, a resilient, synthetic, rubberlike gasket interposed between said metal mem-, ber and said panel, said metal member having a relatively large threaded opening formed therein, a metal bushing having an externally threaded shank for cooperation with said opening, a reciproca-ting actuating member for the switch having a bearing engagement with said bushing, and means associated with said actuating member to assist in rendering said switch substantially oiltight.

8. In an electric switch of the reciprocating contactor type, in combination, a recessed molded insulating base, a contactor-carrying plunger slidable within said recess, a die-cast metal member to which said insulating base is rigidly secured, a perforated panel affording a support for said metal member, a resilient, rubber-like gasket interposed between said metal member and said panel, said metal member having a relatively large threaded opening formed therein, a metal bushing having an externally threaded shank for cooperation with said opening, a reciprocating actuating member for the switch comprising a metal rod of circular cross section having a close sliding fit within said bushing, and means comprising a metal head of mushroom form rigidly attached to the outer end of said rod, the inner end of said mushroom head being adapted to overlap the outer end of said bushing under all conditions to assist in rendering said switch sub stantially oil-tight.

9. In combination, 'an electric switch of the reciprocating contactor type, said switch including a recessed molded insulating base, a cast metal flush plate to the inner surface of which said base is rigidly secured, said flush plate having an opening formed therein, a switch operating element positioned within said opening, said flush plate having an annular recess formed in the lower surface thereof, a diaphragm composed of flexible, liquid-tight material having its peripheral edge portion positioned within said annular recess and clamped therein as an incident to rigid securement orsaid base to said flush plate, the central portion of said diaphragm having means associated therewith to provide for liquid-tight connection thereof to a reciprocating part ofthe switch, and said diaphragm including a-refiexed web portion between said peripheral and central portions to provide for movement of said central portion throughout a predetermined relatively large range corresponding 'to the movement of the switch contactor.

CLYDE F. ROBBINS.

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