US2486033A

US2486033A - Snap acting device

Info

Publication number: US2486033A
Application number: US645876A
Authority: US
Inventors: Oscar H Kaminky
Original assignee: FIRST IND CORP
Current assignee: FIRST IND CORP; FIRST INDUSTRIAL Corp
Priority date: 1946-02-06
Filing date: 1946-02-06
Publication date: 1949-10-25
Anticipated expiration: 1966-10-25
Also published as: GB622507A; FR941376A

Description

Oct. 25, 1949. o. H. KAMINKY SNAP ACTING DEVICE 2 Sheets-Sheet 1 Filed Feb. 6, 1946 Oct. 25, 1949; o. H. KAMINKY 2,486,033

SNAP ACTING DEVICE Filed Feb. 6, 1946 2 Sheets-Sheet 2 Patented Oct. 25, 1949 UNITED STATES PATENT OFFICE SNAP ACTING DEVICE Application February 6, 1946, Serial No. 645,816

13 Claims. 1

My invention relates to electrical snap switches of the compact precision type, and is more particularly concerned with an improved construction which eliminates the many rivets and screws employed inconventional switches of this type to hold the "parts together. By referring to the switch of niy'invention as being of the precision type," I means one which operates in responseto very slight movement of an operating plunger and one 'ich is -intended to operate consistently at the sai'iiefiposition of the plunger. One comto such slight motion and pressure, extreme care and accuracy has been required in its manufacture inasmuch as the operation of the conventional switch can be impaired very materially by slight misadjustments of its mechanism. Nonuniform performance resulting from such misadjustment is unavoidable to a certain extent in the conventional switch where individual parts of the operating mechanism are assembled and held within the housing by means of a number of screws or rivets.

A primary object of my invention, therefore, is the provision of a switch mechanism which can be assembled without the use of a single screw or'rivet to hold any individual part in place, the parts being inserted in slots and recesses molded in the switch housing, all parts being maintained within these slots and recesses by a cover plate which is held in place by any suitablesfastening means, as for instance a single rivet.

Another object of my invention is the provision of a precision switch which can be assembled quickly by unskilled labor without detriment to its performance characteristics, thereby permitting it to be manufactured inexpensively in large quantities. 7

An important advantage resulting from my improved construction is that I can dispense with the extra housing volume required in conventional switches to accommodate the internal high capacity switch of hitherto unknown coinpactness. My switch is so compact that it may be used, for example, in certain small instruments where the use of a switch has long been desirable but has been heretofore impracticable with the relatively bulky switches available; thus my invention represents a significant step forward in the art of instruments as well as that of switches.

Other objects and advantages will appear from the following description and the accompanying drawings, in which- Figure 1 is a side view, constituting a plane section through the cover-housing interface, of a single pole double throw switch showing one modification of my invention;

Fig. 2 is a side view similar to Figure l'showing the plunger depressed and the movable contacts in the opposite position;

Fig. 3 is a section on the line 3-3of Figure-1, but showing the cover in place;

Fig. 4 is a section on the line 4-4 of Figure 1, showing the cover in place;

Fig. 5 is a section on the line 5-5 of Figure 1, showing the cover in place;

Fig. 6 is a section on the line 6-6 of Figure 1, showing the cover in place;

Fig. 7 is a side view, constituting a plane section through the cover-housing interface, of a single pole double throw switch showing another modification of my invention;

Fig. 8 is a side view similar to Fig. '7 showing the plunger depressed and the movable contacts in Like reference characters refer to like parts throughout the drawings. a

The switch illustrated is generally similar to that shown in my copending application entitled Snap acting control mechanism, Serial No. 640,725, filed January 12, 1946. Referring now in detail to the drawings, the modification shown I in Figs. 1-6 comprises a housing generally designated 2| having: the body or base portion 22 having

upstanding end walls

23 and 24 and side walls 26 and 21; the cover plate 28 having the transversely extending positioning boss 30 adapted to help maintain the cover plate in place upon the open side of the housing; first and

second terminal members

29 and 3|, carrying spaced stationary contacts or stops 32 and 33 respectively, and extending through apertures 34. and 36 in the end wall 24; a third terminal member or mounting bracket 31 extending through aperture 36 in the side wall 21 and which in this embodiment comprises offset mounting portions interconnected by a bridging portion; the actuator member 39 having the knife edge 4| pivotally engaging the groove 42 formed in terminal member 31; an overcenter snap spring system comprising an approximately rectangular-shaped resilient metal strip generally designated 43, having compression element 44 pivotally engaging the groove 46 formed in the terminal member 31, the tension elements 41, the end portion 48 pivotally engaging the groove 49 formed in the actuator 39, the distance between the grooves or

recesses

46 and 49 being sufiiciently greater than the unstressed distance between the end portion 48 and the end of the compression element 44 that when assembled as shown the compression element is bowed upwardly and stressed in compression and the tension elements are stressed'in tension; the plunger member 5I reciprocable within the aperture 52 formed in side wall 26 and having the enlarged inner end portions 53 to maintain it within the housing. Normally the actuator or lever 39 will be maintained resiliently pressed against the inner end surface 54 of the plunger by the spring member 43. The

terminal members

29, 3| and 31 will be fitted with suitable means for connecting external wires, as for instance with the screws 56.

Transversely extending lugs 51 are formed on the inner end portions of the

terminal members

29 and 3| and are closely fitted within the recesses 56 formed in the housing and cover plate. The inner end or mounting portion 35 of terminal member 31 is closely fitted within the recess 40 formed in the wall 26 of the housing. The engagement of the inner end portions by these recesses, combined with the closely fitting engagement of their intermediate portions within the

apertures

34, 36 and 38, serve to secure the terminal members immovably in their proper positions. It will be obvious that with the terminal members so secured the spring member 43, actuator 39 and plunger 5| will seek the positions shown in Fig. 1.

In assembling the switch the advantages of this construction which eliminates the conventional screws and rivets are at once apparent. Since each of the four

apertures

34, 36, 38 and 52 have one side open in the direction of the housing open side, assembly is readily carried out as follows: The plunger 5| is inserted within the aperture or slot 52: the spring member 43, the actuator 39 and the terminal member31 are fitted together outside the housing as a sub-assembled unit which is then inserted so the housing engages the terminal member 31 at the recess 40 and at the a erture 38:

terminal members

29 and 3| are then fitted within the

apertures

34 and 35 with l gs 5 engaging housing recesses 58; and cove plate 28 is attached by any suitable means as by a rivet (not shown) fitted within the housin rivet hole 59 and within a similar hole (not shown) in the cover plate, the cover plate being maintained from rotation about the rivet hole by the engagement of the positioning boss 36 within the space between the terminal members 2'1 and 3|; and by engagement of termina lugs 51 within cover plate recesses 58. The boss 30 serves additionally to help maintain the

terminals

29 and 3| in properly spaced relation.

The position or the parts shown in Figure 1 is the normal position of the switch mechanism, the movable contact 20 being disposed in engagement with the stationary contact 32. When the plunger 5| is depressed the actuating member 39,is depressed from the position of Figure 1 to the position of Fig. 2, during which movement the groove 49 on the actuating member is moved downward toward the compression centerline of the spring member against the compression of the compression element 44. In the particular switch shown. the axis or position of maximum stress is reached when the groove 46 is coplanar with the tension members 41 and when the tension members are moved downwardly through this axis the spring member reverses its position to that shown in Fig. 2 with a snap movement; similarly, when the depressive force in the plunger is released the spring member will move upwardly under the influence of fiexural forces stored in it until the tension elements pass the above-mentioned coplanar position whence it moves to the position shown in Fig. 1, by snap action.

The modifica ion shown in Figs. '1 to 12 is substantially the same in construction and operation as that shown in Figs. 1 to 6 except that the actuator moves the compression element I44 (instead of the tension elements 41) to snap the spring member between the stationary contacts. The

modification shown in Fig. '1 is of the center plunger type which may be preferred for particular applications; and the terminal members extend through only the end walls of the housing whereby the switch may be conveniently employed in a flush mounted position against a wall.

Referring, now, specifically to Figs. '7 through 12, this modification comprises a housing generally designated I2I having: the body or base portion I22 having upstanding end walls I23 and I24 and side walls I26 and I21; the cover plate I26 having the transversely extending positioning boss I36 adapted to hold the cover plate in place upon the open side of the housing; first and second terminal members I29 and I3I carrying spaced stationary contacts or stops I32 and I33 respectively, and extending through apertures I34 and I36 in the end wall I24; a third terminal member I31 extending through aperture I 36 in the end wall I23; an actuator member I39 having the knife edge I4I pivotally engaging the groove I42 formed in the terminal member I31; an overcenter snap spring member comprising an approximately rectangular shaped resilient metal strip designated I43, having compression element I44 pivotally engaging the groove I46 formed in the actuator member I39, tension elements I41, the end portion I48 pivotally engaging the groove I49 formed in the terminal member I31, the distance between the grooves I46 and I49 being sufliciently greater than the unstressed distance between the end portion I48 and the end of the compression element I44 that when assembled as shown the compression element is bowed downwardly and stressed in compression and the tension elements are stressed in tension; the plunger member I5I reciprocable within the aperture I52 formed in the side wall I26 and having the enlarged inner end portions I53 to maintain it within the housing. Normally, the actuator I39 will be maintained resiliently pressed against the inner end surface I54 of the plunger by th spring member I43. The terminal members I29, I3I and I31 will be fitted with suitable means for connectpended claims.

' the inner end portions of the terminal members I23 and I3I and ar closely fitted within the receases Ill formed in the housing and in the cover plate. The inner end portion I33 of terminal member I3! is closely fitted within the recess I4Il formed in the side wall I23. The engagement of the inner end portions by thes recesses, combined with the closely fitting engagement of their intermediate portions within the apertures I34, I33 and I33, serve to secure the terminal members immovably in their proper positions. It will be obvious that with the terminal members so secured the spring member I43, actuator I33 and plunger I3I will seek the positions shown in Fig. '7. v Assembly of the center-plunger switch is carried out in the same manner as that described for the end-plunger switch, the spring member I43, the actuator I33 and the terminal member I31 being fitted together outside the housing and inserted as a sub-assembled unit.

The position of the parts shown in Fig. 7 is the normal position of the switch mechanism, the movable double-faced contact I20 being disposed in engagement with the stationary contact I33. When the plunger II is depressed the actuating member I33 is depressed from the posi tion of Fig. '7 to the position of Fig. 8, during which movement the groove I46 on the actuating member is moved downward toward the compression center line of the spring member against the compression of th element I44. In the particular switch shown, the axis or position of maximum stress is reached when the groove I46 is coplanar with the tension members I41 and when the groove is moved downwardly through this axis, the spring reverses its position to that shown in Fig. 8 with a snap movement; similarly, when the depressive force on the plunger is released, the compression element will move upwardly under the influence of fiexural forces stored in it until the groove I46 passes the above mentioned coplanar position whence the spring member will move to the position shown in Fig. ,7 by snap action.

I The end plunger switch isconstructed to be self-returning to the Fig. 1 position by placing th contact or stop 33 so the plane containing tension elements 41 cannot cross the pivot 42.

It may be constructed to be non-returning either by raising the pivot 42 or by lowering the contact or stop 33 so that in passing between the Figures 1 and 2 positions the plane will cross that pivot.

Similarly, the center plunger switch is constructed to be self-returning to the Fig. '7 position by placing the contact or stop I32 so the plane containing tension elements I41 cannot cross the pivot I4I. It may be constructed to be non-re-' turning either by raising the pivot I4I or by raising thecontact or stop I 32 so that in passing between the Figures 7 and 8 positions the plane will cross that pivot.

While I have thus described two specific embodiments of my invention I am aware that numerous alterations and changes may be made therein without materially departing from the spirit of the invention and the scope of the ap- For example, instead of a single pole double throw switch as illustrated in both embodiments, my invention is equally applicable to other contact combinations, such as a single pole single throw switch, or a double pole double throw switch. Furthermore, in some modifications the reciprocable plunger SI maybe replaced by other means for moving the actuator member, as, for instance, in service where it is desired to seal the housing against the entrance of dust or moisture, the actuator 39 may be actuated through a diaphragm or bellows (neither shown) fitted into the housing, or the actuator may be actuated by a magnetic element (not shown) positioned exteriorly of the housing, or by any other suitable operating means. In some instances it may be desirable for special purposes to dispense with some or all of the lugs 51 which are engaged by the recesses 58 for under some service conditions it may be sufficient to secure the terminal members, or some of them, within the housing solely by engagement with the slots formed in the walls; a but for the best advantage it will be preferable where possible to mount the terminal members securely at their interior end portions in addition to fitting them into wall apertures.

I claim:

1. In an electric snap switch the combination 'of: a housing of insulating material including a cover plate and a body with an open side normally closed by the cover plate; said housing having apertures therein adjacent the body-cover interface fittedly engaging terminal members and a reciprocable plunger, two of said terminal members having stationary contacts attached thereto; each of said apertures having an open side at said body-cover interface whereby saidterminal members and said plunger are insertable into said housing through said housing open side; said two terminal members being secured in said housing by transversely extending lugs on said terminal members engaging recesses formed in said cover plate and in said body portion; an actuating member pivotally engaging a third of said terminal members and movable by said plunger; a spring member made of a resilient metallic strip having spaced side portiolgs comprising elongated tension elements and having end portions connecting said tension elements, one of said spring member end portions having an inwardly extending compression element, said spring member being so fitted within said housing and its parts so proportioned. and so dimensioned that its compression element is pivotally compressed upon said third terminal member and the spring member end portion opposed to said compression element is pivotally engaged with said actuator member in such a manner as to stress said tension elements in tension whereby, when said plunger is depressed, said actuating member will move said tension elements to move said spring member to carry said movable contact from one of said stational'y'contacts to the other in a snap action manner.

2. An electric snap switch, comprising a housing including a, cover plate and a body with an open side normally closed by the cover plate, said housing having first, second and third spaced slots opening at the body cover interface, terminal members shaped to be received in said first and second slots, means integral with said terminals adapted to co-act with the housing to position the terminals therein, said terminals being insertable in said housing through the open side thereof, a spring member having a contact movable between said terminal members, said spring member having an axis of maximum stress and being formed from a resilient metal strip, said spring member having the general shape of a rec tangular frame comprising long sides and short 7 sides interconnecting opposite ends of the long sides, one of said shorter sides having a portion extending inwardly of said frame between the long sides, a bracket defining another terminal member and shaped to be received in said third slot and supporting said inwardly extending portion so that the latter is in compression, an actuating member shaped to support the other of saidshort sides so that the long sides are under tension, said bracket pivotally supporting said actuating member so that said bracket, said actuating member and said spring form a unit insertable in said housing through the open side thereof, and means extending through said housing engaging said actuating member to move said spring member through its axis of maximum stress and thereby move said movable contact between said terminal members witha snap action,

3. An electric snap switch, comprising a housing including a cover plate and a body with an open side normally closed by the cover plate, said housing having first, second and third spaced slots opening at the body cover interface, terminal members shaped to be received in said first and second slots, means integral with said terminals adapted to coact with the housing to position the terminals with respect thereto, said terminals being insertable in said housing through the open side thereof, a spring member having a contact movable between said terminal members, said spring member having an axis of maximum stress and comprising spaced tension members interconnected at opposite ends, one

a pivotally mounted rigid lever, movable between preselected positions, and an overcenter snap spring system comprising a compression member and spacedtension members, said tension members being interconnected at opposite ends, one of said interconnected ends being free to move between preselected positions with a snap action, said compression member having one end interconnected with said free end and the opposite end pivotally supported by said bracket and said other interconnected end of the tension members being pivotally supported by said lever whereby movement of said lever about its pivotal mounting shifts said tension member relative to the compression member to move said free end between the preselected positions.

6. In a snap action device, the combination of a snap spring system comprising spaced tension members interconnected at a first end and a second end thereof and a compression member intermediate said tension members and interconnected at one end with said first end, said first end being free to move between preselected positions with a snap action, a bracket disposed between said tension members comprising mounting portions atsubstantially right angles to the plane of the tension members and offset with respect to each other and a"bridging portion interconnecting the offset portions and in substanof said ends being free to move between said tersertable in said housing through the open side thereof, means disposed between said bracket and said housing to position said bracket therein, and a plunger mounted on said housing and engaging said actuating member to move said tension members relative to compression member through the axis of maximum stress and thereby efiect snap movement of said movable ,contact between said first mentioned terminal members.

4. In a snap action switch, the combination of a support, opposed stops on said support, a

bracket mounted on said support in spaced relation with said stops, a rigid lever pivotally mounted on said bracket for movement toward or away from said support, means for limiting the movement of said lever, and a snap spring system having an axis of maximum stress and comprising a compression member and a tension member, one end of each of said tension and compression members being free to move between said opposed stops, the opposite end of said compression member being pivotally supported by said bracket and the opposite end of said tension member being pivotally engaged by said lever whereby movement of said lever shifts said tension member relative to said compression member through said axis of maximum stress to move said free ends between the opposed stops with a snap action. I

5. In a snap action switch, the combination tially parallel relation with the plane of the tension members, means for rigidly supporting each of said mounting portions, one of said mounting portionshaving a recess adjacent one side of the bridging portion pivotally receiving the opposite end'of the compression member, said other mounting portion having a recess adjacent the opposite side of the bridging member, ,a lever extending through the plane of the tension members and having an end pivotally received in said latter recess, said lever having its opposite endmovable between preselected positions, said lever having a recess for pivotally supporting the second end of the tension members positioned to stress said tension and compression members to produce a snap spring system having an axis of maximum stress, and a reciprocable plunger engageable with said lever to move said second end of the tension members through the axis of maximum stress to actuate the snap spring system.

7. In a snap action device, the combination of a snap spring system comprising a first stressed member and a second stressed member mounted at one end and connected at their opposite ends to form an end free to move between preselected positions with a snap action,'a bracket for mounting said spring system, said bracket having mounting portions extending generally outwardly from each side of the spring system and a bridging portion interconnecting said mounting portions, means for rigidly supporting each of said mounting portions, one of said mounting portions having a recess on one side of the bracket pivotally receiving the mounted end of one of the stressed members, said other mounting portion having a recess on the opposite side of the bracket, a lever extending through the plane of the other stressed member and having an end pivotally received in said latter recess, said lever having a recess for pivotally supporting the mounted end of the other stressed member positioned to stress said members to form a snap spring system having an axis'of maximum stress and a reciprocably mounted plunger engageable with said, lever to of a support, a bracket mounted on said support, '15 move the mounted end of one of the stressed members through the axis 01' maximum stress'to actuate the snap spring system.

8. In a snap action device, the combination of a support, a bracket having portions oflset with respect to one another and a bridging portion interconnecting said onset portions, means acting between each portion and the support for rigidly supporting said portions on the support, a lever movable between preselected positions having one end pivotally mounted on one of said portions and extending in substantially parallel relation with said bridging portion and having its opposite end in spaced substantially parallel relation with said other portion, a snap spring system comprising a first stressedmember and a-second stressed member interconnected at one end to form an end free to move between preselected positions with a snap action, the opposite end of the first stressed member being pivotally supported on the other of said portions on the opposite side of the bridging member, and the opposite end of the second stressed member being pivotally supported by said lever to stress said members to form a snap spring system having an axis of maximum stress, and plunger means engageable first and second slots, means integral with said terminal members adapted to coact with the housing to position the terminal members wth respect thereto, said terminal members being insertable in said housing through the open side thereof, a spring member having a, contact inovmounting said first stressed member in a stressed condition, a bracket defining a terminal accessible with the lever to move said second stressed memher through the axis of maximum stress to actuate the snap spring system.

9. In an electric snap switch the combination of a housing of insulating material including a cover plate and a body with an open side normally closed by the cover plate, said housing having apertures therein adjacent the body-cover from the exterior of the housing shaped to have a portion snugly received in said recess and a portion received in said third slot to rigidly suport said bracket in said housing, said bracket being shaped to support said second stressed member in a stressed condition, and to form with said stressed members and said actuating member a snap spring system having an axis of maximum stress, said bracket pivotally supporting said actuating member so that said bracket, said actuatin member and said spring member form an assembly insertable as a unit into said housing through the open side thereof, and means mounted on said housing and engaging said actuating member to move said first stressed mem- A -ber relative to the mounting of the second stressed interface, a reciprocable plunger shaped to be received in one ofsaid apertures, terminal members to be received in the other of'said apertures, two of said terminal members'having stationary contacts attached thereto, each of said apertures having an open side at said body-cover interface whereby said terminal members and said plunger are insertable into said housing through said open side of the housing, said two terminal members being secured in said housing by transversely extending lugs on said terminal members engaging recesses formed in said cover plate and in said body portion, an actuating member pivotmember on the bracket and thereby move snap spring system through its axis of maximum stress whereby said free end moves between the first mentioned terminal members with a snap action. l

11. In a self-return'snap acting device, the combination of a snap spring system comprising a first stressed member and a second stressed member forming tension and compression members, mounted at one end and connected at their opposite ends to form an end free to move between preselected positions with a snap action, a bracket for mounting said spring system having mounting portions extending generally outwardly from each side of the spring system, means for rigidly supporting each of said mounting portions, one of said mounting portions having a really supported by a third of said terminal members and engageable by said plunger, a spring member insertable in said housing through the open side formed of a resilient metallic strip, said spring member having spaced side portions comprising elongated tension elements and having end portions connecting said tension elements, one of said spring member end portions having an inwardly extendin compression element, said spring member being so fitted within said housing and its parts so proportioned and so dimensioned that its compression element is pivotally supported upon said actuating member and the end portion opposed to said compression element is pivotally supported by said third terminal member to stress said tension elements in tension whereby, when said plunger is depressed,

cess on one side of the bracket pivotally receiving the mounted end of one of the stressed members, said other mounting portion having a recess on the opposite-side of the bracket, a movableleverextending through the plane of the other stressed member, said lever having an end pivotally received in said latter recess, said lever having a portion .with a recess for pivotally supporting the mounted end of the otherstressed member, spaced stop means engageable with said lever to limit movement of said recessed portion between opposed positions disposed on one side of a line defined by the pivotally mounted end of the lever and said free end, said positions also being disposed on opposite sides of a straight line passing through the mounted end of said one stressed member and said free end, said stressed members and mounting means defining a spring system normally biasing said lever to urge said portion to one of said opposed positions,

and a plunger. operative against said lever to move said portion from said one opposed position to the other opposed position to move the mounted end of one of the stressed members past the mountedend of the other stressed member to actuate said spring system, said portion upon release of 'force on said plunger returning to said one opposed position through biasing action of said spring, system to again actuate the spring system.

12. An electric snap switch, comprising a housing including a cover plate and a body with an open side normally closed by the cover plate, said housing having first, second and third spaced slots opening at the body cover interface, terminal members shaped to be received in said first and second slots, means integral with said terminals adapted to coact with the housing to position the terminals therein, said terminals being insertable in said housing through the open side thereof, a spring member having a contact movable between said terminal members, said spring member having an axis of maximum stress and being formed from a resilient metal strip, said spring member having the general shape of a rectangular frame comprising long sides and short sides interconnecting adjacent ends of the long sides, one of said shorter sides having a portion extending inwardly of said frame between the long sides, a bracket definin another terminal member and shaped to be re ceived in said third slot and supporting one of said short sides, an actuating member shaped to support said inwardly extending portion to stress said latter portion in compression and said long sides in tension, said bracket pivotally supporting said actuating member so that said bracket, said actuating member and said spring form a 12 terminals bein'g insertable in said housin through the open side thereof, a spring member having a contact movable between said terminal members, said spring member having an axis of maximum stress and comprising spaced tension members interconnected at opposite ends, one of said ends being free, to move between said terminals with a snap action, a compressionmember having an end integrally interconnected with said free end, a bracket defining another terminal accessible from the exterior of the housing shaped to be received in said third slot to support the opposite end of said tension members, a rigid actuating member pivoted on the bracket and supporting the opposite end of said compression member, said bracket, said actuating member and said spring forming a unit insertable in said housing through the open side thereof, means disposed between said bracket and said housing to position said bracket therein, and a plunger mounted on said housing and engaging said actuating member to move said compression member relative to tension members through the axis of maximum stress and thereby eiiect snap movement of said movable contact between said I first mentioned terminal members.

unit insertable in said housing through the open side thereof, and means extending through said said housing having first, second and third spaced slots opening at the body interface, terminal members shaped to be received in said first and second slots, means integral with said terminals adapted to coact with the housing to'position the terminals with respect thereto, said OSCAR H. KAMINKY.

REFERENCES CITED The following references are of record in the file of thispatent:

UNITED STATES PATENTS Number Name Date 1,282,816 Guett Oct. 29, 1918 2,157,156 Abendroth May 9, 1939 2,170,748 Eaton Aug. 22, 1939 2,228,522 Johnson Jan. 14, 1941 2,228,523 Johnson Jan. 14, 194i 7 2,235,382 Miller Mar. 18, 1941 2,332,911 Hausler Oct. 26, 1943 1 2,368,679 Popp Feb. 6, 1945. 2,370,479 Meyer -1 Feb. 27, 1945 2,374,986 Fetter May 1, 1945 2,403,051 W Christensen July 2, 1946- 2,417,169 Kaminky Mar. 11, 1947