US3163740A

US3163740A - Push-button switch assembly

Info

Publication number: US3163740A
Application number: US180499A
Authority: US
Inventors: Philip C Ross
Original assignee: PATENT LICENSE CORP
Current assignee: PATENT LICENSE CORP
Priority date: 1962-03-19
Filing date: 1962-03-19
Publication date: 1964-12-29
Anticipated expiration: 1981-12-29

Description

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RUSH+BUTTON SWITCH'E ASSEMBLY 3 Sheets-Sheet 1 F'iTedlMazmh 19, 1962 H w MH III J 7 6 .f 4 E 7 4 4T 4 H9 v VIII- a 6 9 6 4 I HI IHL oWA A 4/ ATTY'S.

Dec. 29, 11964 P. re. :RQSS

RUSH-summon swmrrca ASSEMBLY :Sheets-ISheei :5

Filed March 19,, 1962 INVENTOR.

PHILIP C. ROSS ATTY'S.

United States Patent 3,163,740 PUSH-BUTTON SWETCH ASSEMBLY Philip C. Ross, Costa Mesa, Calih, assignor to Patent License Corporation, Chicago, BL, a corporation of Illinois Filed Mar. 19, 1962, Ser. No. 189,499 9 (Ziaims. (Cl. 2tt0l63) The present invention relates to a new and improved switch assembly of the push-button type, the assembly making use of a unique arrangement of relatively movable parts to provide efiicient operation and improved compactness of design. More specifically, the invention deals with a new and improved push-button switch assem bly particularly adapted for use in the control of electronic apparatus such as computers, program controllers and the like, the assembly including a new and improved switch blade mounting and actuation arrangement and, among other features, a positive gas and moisture sealing arrangement, all of the improvements being especially designed and arranged for compactness.

With the present day complexities in electronic equipment, such as computers, controllers and the like, increasing demands are being made on the overall operational and design features of component electrical and electromechanical parts. The operating panel of a computer must be within prescribed size limitations and yet include the necessary basic switches or other components required to operate the uni-t. Still further, new uses of computers and the like are continuously being made and operation thereof can occur under unusual conditions. For example, it may be essential that the computer be sealed from the atmosphere which might include moisture, damaging gases or the like, or that the computer or other control device form a part of a sealed system and must be sealed itself.

Difiiculties have been encountered in attempting to reduce the overall size of basic electromechanical parts, such as switches or the like, and yet retain the requisite positive and dependable operation thereof. In this regard the number of moving parts should be maintained at a minimum and the length of travel of such parts should be held as short as possible. A reduction in the number of moving parts and the length of available travel can adversely affect the basic electro-mechanical action required. In this respect, the present invention deals with the maintaining of an adequate distance of travel of a movable contact end of a switch blade between fixed circuit contacts to avoid undesirable arcing and retain adequate positive action, and yet also reduce the overall size of the switch assembly. Additionally, the invention deals with limiting the number of moving parts to those which are best capable of resisting damage as a result of extended operation. With improved compactness of design constituting the basic purpose of the invention, it is also within the scope thereof to add an efficient sealing arrangement which, by reason of its design, does not interfere with the basic-purpose in mind.

Therefore, it is an object of the invention to provide a new and improved switch assembly of compact design and efficient operation.

Another object is to provide a push-button type switch assembly utilizing a uniquely designed and arranged switching action which retains the basic benefits of efficient switch operation while materially reducing the amount of space required for such operation.

A further object is to provide a new and improved switch assembly including as a part thereof a special sealing arrangement establishing an etficient gas and moisture seal and subject to ready maintenance Within minimum space requirements.

An overall object is to provide a new and improved "ice switch assembly combining therein new and improved electrical and mechanical operating parts which are arranged to obtain improved efiiciencies both with respect to continued positive operation thereof and prolong trouble-free life. 7

Other objects not specifically set forth will become apparent from the following detailed description of the invention made in conjunction with the accompanying drawings wherein:

FIG. 1 is a fragmentary perspective of the switch assembly of the present invention. illustrating the same coupled with a solenoid holding unit;

FIG. 2 is a fragmentary longitudinal section of the assembly as viewed generally along line 22 in FIG. 3;

FIG. 3 is a fragmentary longitudinal section of the assembly taken generally at right angles to FIG. 2 as viewed along line 3-3 therein;

FIG. 4 is a transverse section of the assembly taken generally along line 4-4 in FIG. 2;

FIG. 5 is a bottom end elevation of the assembly;

FIGS. 6 and 7 are schematic illustrations. of the operational features of the switch blades forming a part of the assembly; 7

FIG. 8 is a perspective of the preferred type of sealing ring used in the assembly; and

FIG. 9 is a perspective of another form of sealing ring suitable for use in the assembly.

As best shown in FIGS. 1-3, the switch assembly 10 comprises a hollow body portion 11 of generally rectangular shape provided with a transverse end wall portion 12 closing ofi one end thereof. The opposite end 13 of the body portion 11 has slidably received therein a. push-button member 14 which is connected through a pair of resilient finger-like members 15 to a transverse plate 16 mounted in the body portion ii and dimensioned for sliding movement therein longitudinally thereof. The transverse plate 16 has attached thereto one end of a push rod 17 which is suitably journaled through the end wall 12 of the body portion and which externally of the body portion may be suitably attached to a holding solenoid 18 (FIG. 1).

The end wall 12 has mounted therethrough a plurality of fixed contact plates 19. A plurality of reversely arcuately folded switch blades 21B are mounted in the body portion between the transverse plate 16 and the end wall 12 for actuation in a manner to be described upon longitudinal movement of the transverse plate 16 in the body portion. A separate but uniquely arranged lamp unit 21 is mounted in the body portion 11 between the transverse plate 16 and the outer end portion of the push-button member 14. The basic assembly is completed by the provision of a special type of sealing ring 22 (FIG. 1) or 23 (FIGS. 2 and 3).

Referring specifically to the individual components, the push-button member consists of a continuous transverse end wall portion 24 provided with an axial peripheral skirt portion 25 (FIG. 3) thus providing the member with a general cup-shape. The resilient finger-like members 15 are suitably permanently attached to the outer end surface portion of the skirt 25 and project therefrom in oppositely positioned relation in close association with the internal surface portions or" the body portion 11. As best shown in FIGS. 1 and 3, the finger-like members 15 cooperate with the transverse end wall 24 and the skirt 25 to define therebetween a continuous peripheral, outwardly opening groove 26 in which the,

.134 which engage the. enlargements 33.

portion and is angled outwardly of the groove 26 for sliding engagement with inner surface portions of the body portion 11. The chevron sealing ring 22 will normally be mounted in the position shown in FIG. 1 in which position the interior of the switch assembly is sealed from the atmosphere. Any external gas pressure is active between the flexible lip portion 28 and the base portion 27 to urge the lip portion into tighter sealing engagement with the inner surfaces of the body portion 11. 1f the arrangement is such that the sealing ring is intended to prevent gas leakage from the interior of the switch assembly or the interior of the computer or the like, the sealing ring 22 is formed to seal in the opposite direction.

' The sealing ring 23 is of generally solid configuration being provided along the outer and inner surfaces thereof with peripherally continuous recesses 29 which define a pair of enlargements to each side thereof for double engagement with the base of the groove 26 and the inner surface portions of the body portion 11. The operative mounting of the sealing ring 23 is shown in FIGS. 2 and 3. This ring is capable of sealing in either direction at all times.

The unique feature of the

sealing rings

22 and 23 is the rectangular shape thereof, this being a predetermined, permanently molded shape. The rectangular or generally square shape of the switch assembly permits better utilization of available space in conjunction with the specific types of components making up the same. In attempting to internally seal an assembly of this shape, it has been found that the use of a standard O-ring of the like creates some undesirable problems. Such an O-ring is either rather tightly received in the mounting groove 26 by reason of stretch requirements to transform the same into generally rectangular shape, or if over-dimensioned for this purpose, it is too loosely received in the mounting groove to permit efiicient functioning. Furthermore, an annular shape which does not conform to the generally rectangular shape of the switch assembly does not permit the establishment of an efiicient seal at the corners of 'exact shape of the mounting groove 26. In this manner eachsealing ring is mounted in a. substantially relaxed condition in the mounting groove and the frictional forces exerted against the inner surfaces of the body portion do not create excessive resistance to the operation of the switch assembly and yet provide a highly efiicient sealing function. Thus by special shaping of the sealing rings the same are mounted in relatively relaxed confirmation to the rectangular shape of the groove 26 'and body portion 11.

The transverse plate 16 is provided with substantial clearance relative to the inner surfaces of the body portion 11. The plate extends between the inner ends of a the finger-like members with these members being detachably connected to opposite margins of the plate 16.

FIG. 3 illustrates opposite margins of the plate 16 being formed with protecting abutment ledges 31 against which the ends of the finger-like members are received for the purpose of applying switch actuating pressure to the plate to move the same toward the end wall 12 of the body portion 11. Inwardly ofthe ledges 31 are grooves 32 into which inwardly directed enlargements 33 formed on the ends of the finger-like members 15 are frictionally received. The grooves 32 terminate in locking tongues With this arrangement the finger-like members 15 positively engage the'transverse plate 16 to depress the samein the body portion 11 and yet are readily detachable therefrom if the push-button member 14 is grasped and withdrawn from the body portion 11.

The push rod 17 is suitably journaled and fixed in the center of the transverse plate 16 by an enlarged locking end portion 35. The push rod extends through a sleeve 36 received in a projecting collar 37 formed centrally in the end wall 12 to define a push rod bore. The sleeve includes a peripheral enlargement 38 at the inner end thereof which is suitably received in an annular seat formed in the end wall 12 and a coil spring 39 is seated between the inner end of the sleeve 36 and the bottom surface of the transverse plate 16. The sleeve 36 projects outwardly beyond the collar 37 and, as shown in FIGS. 1 and 2, is externally threaded to receive thereon the solenoid 18. A locking nut 40 is received on the outer threaded end of the sleeve 36 to hold the same in fixed position within the collar 37. The push rod reciprocates through the sleeve 36 and is formed at its outermost end with an enlargement 41 which overextends the outer end surface of the sleeve 36 acting to hold the spring 39 in compression. The enlargement 41 is electrically responsive to the solenoid holding unit 18 in the known manner and upon actuation of the switch assembly 10, the push rod may be held outwardly in its extended position by the solenoid 18. The switch assembly is not limited to use with a solenoid but this is one of its standard uses in accordance with conventional practices involving computer switches and the like. it will be understood that any known type of switching action may be accomplished with the switch assembly of the present invention, such action including alternate action, solenoid held action, etc.

The contact plates 19 in the form illustrated are flat metallic strips which are fixed in the end wall 12 of the body portion 11 and project therethrough externally and internally of the body portion. The outer ends of the contact plates lit may be formed with suitable apertures 42 for lead connection therewith. Switching action to make and break various circuits controlled by the switch assembly It) is brought about by depression of the pushbutton member 14 into the body portion 11 accompanied by movement of the transverse plate 16 towards the closed end 12. as previously described. Movement of this plate results in actuation of a plurality of switch blades 20 mounted in the body portion in association with the contact plates 19. The particular switch assembly illustrated involves the use of four switch blades 2% located adjacent the four corners of the body portion. The single switch blade shown in FIG. 1 and the pair of switch blades shown in FIG. 2 are considered adequate for the purpose of describing their design and function.

It is known that the distance of travel of a switch blade between contact points is of material importance with regard to the problem of arcing as well as fast action. These considerations are not necessarily compatible as it can be said as a general premise that while a shorter distance of travel will normally provide faster action, the problem of arcing becomes greater. Similarly, an increase in the travel reduces arcing and also reduces speed of response. Where adequate space is available, these problems canbe readily overcome. However, in attempting to minimize the space requirements, these problems become rather acute.

The switch blades 2i? and their mode of operation alleviate the problems of arcing and response while minimizing the space requirements. Each switch blade, as best shown in FIGS. 2, 6, and 7, is in the form of a reversely arcuately folded resilient member having one end fixed and the other end resiliently movable betweenspaced contacts. Specifically, each switch blade 20 includes a relatively flat leg portion 43, the end of which is suitably fixed to the end of a contact plate 19 projecting into the body portion 11. The leg portion 43 is integrally formed with a resiliently movable leg portion 44 through an arcuate folded portion 45. The leg portion 44 is preferably resiliently bowed in its position of rest as illustrated and furthermore is preferably inclined at least to some degree away from the fixed leg portion 43. The free end of the leg portion 44 is provided with a multiple face contact 46 which is located between a pair of contact plates 19 within the body portion 11. In its mounted condition the switch blade 20 has the contact end thereof confined between 21 pair of contact plates 19 and the configuration and positioning of the leg portion 44 is such that the contact 46 is continuously held in engagement with one of the contact plates 19. The bowed and outwardly inclined positioning of the leg portion 44 supplies a cam actuated surface engaged by an edge portion of the transverse plate 16. Movement of the transverse plate 16 toward the closed end 12 of the body portion in the manner previously described results in the riding of the edge portion of the plate along the inclined bowed leg portion 44 and ultimate camming of the leg portion and free end contact as thereof away from the initially contacted plate 19 and ultimately into circuit making or breaking contact with the spaced contact plate 19 as shown in FIG. 7.

In effect, the switch blade 20 of the present invention is a doubled or reversely folded cantilever leaf spring. By reason of its configuration, the space which it consumes is materially reduced and the distance of travel of the actuating means, in this case the transverse plate 16, is materially shortened. Yet, with this arrangement the requisite distance of travel to prevent arcing is maintained. Additionally, the life and efficiency of the switch blade is equivalent to a conventional cantilever leaf blade as the total length of the blade is retained and the material thereofis not subject to excessive stress or concentrated load. It will be appreciated that the arcuate connecting portion 45 is not fixed in any respect and only the outermost end portion of the leg portion 43 is fixed. This per- .mits full utilization of the resilient and strength properties of the entire blade to accommodate operational stresses and load. The coil spring 39 functions to return the transverse plate 16 to its initial position as well as return the push-button member to its initial outwardly projecting position. At all times during travel of the transverse plate 16 the same is in contact with the switch blades 2!? thus providing for immediate response and control of switch actuation.

The lamp unit 21 is a separate unit mounted in the body portion 11 between the transverse plate 16 and the push-button member 14 and is completely free from any effect from operational use of the transverse plate and the push-button member. It has been conventional to mount lamp units in the push-button member itself thus utilizing available space. This position of mounting has been found undesirable because of the attendant maintenance of the lamp unit arising from damaging thereof by operational shock.

The lamp unit 21 is fixedly mounted in the body portion 11 by reason of a base plate 47 which extends transversely across the interior of the body portion 11 and is anchored along a pair of opposite margins to the body portion 11 as shown in FIG. 2. The remaining opposite margins are spaced substantially inwardly from the adjacent surfaces of the body portion 11 as shown in FIG. 3. In this space the resilient finger-like members 15 extend and are freely movable completely independently of the lamp unit 21. FIG. 4 readily illustrates the clearances established between the fixed and moving parts. There is sufiicient clearance available to permit ready disconnection of the push-button member 14 from the transverse plate 11 for access to the lamp unit for lamp replacement or the like.

The base plate 47 has mounted thereon a pair of lamp mounting clamps 48 which resiliently clamp therein lamps 49 having as a part thereof projecting ears 50 directed upwardly therefrom for ready grasping for lamp removal purposes. As the specific elements carried by the base plate 47 and comprising the lamp unit 21 are of known type and do not form a part of the invention, they will not be described in detail. Color filters 51 may be mounted about the lamps 49 if desired.

The base 52 of each lamp is in contact with an end portion of a contact plate 1% which extends through the end wall 12 closely adjacent the inner surface of the body portion 11 and is completely free from engagement or contact with any of the moving parts of the assembly. The innermost end of the contact 319 may be resiliently urged into engagement with the lamp base by a leaf spring member 53 forming a part thereof. The lamp mounting clamps 48 may be suitably attached to a contact plate 19 which also extends outwardly through the closed end 12 of body portion. Removal of the pushbutton member 1a provides access for ready lamp replacement when necessary.

Obviously certain modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A switch assembly of the push-button type comprising a hollow body portion having an open end and a closed end, a transverse plate in said body portion dimensioned for sliding movement longitudinally thereof, push rod means journaled through the closed end of said body portion for reciprocal movement therethrough and fixed to said plate, push-button means slidably received in the open end of said body portion, said push-button means being generally cup-shaped with a continuous transverse end wall portion joined with an axial peripheral skirt portion and provided with resilient finger-like members projecting axially therefrom along inner surface portions of said body portion into releasable connection with edge portions of said plate, the end wall portion of said pushbutton means projecting from the open end of said body portion, said skirt portion inwardly of said end wall portion being circumferentially recessed to define a groove opposed to the inner surface portions of said body portion inwardly of said open end, a continuous sealing ring mounted in said groove and in resilient sliding sealing engagement with said inner surface portions, a plurality of electrical contact plates projecting through said closed end on either side thereof internally and externally of said body portion, and at least one reversely arcuately folded switch blade in said housing formed from resilient material and having one end thereof fixed to define a circuit connection and the other end thereof provided with a multiple face contact thereon and freely movable between spaced inner ends of a pair of contact plates for alternate electrical connection therewith, said switch blade being positioned for camming engagement of the free end thereof by said transverse plate during movement thereof toward said closed end to move said face contact out of engagement with one contact plate and into engagement with another.

2. The switch assembly of claim 1 wherein a lamp unit is fixedly mounted in said body portionbetween said transverse plate and said push-button means, the fingerlike members of said push-button means sliding freely through said lamp unit during movement of said transverse plate.

3. A switch assembly of the push-button type comprising a hollow body portion having an open end and a closed end, a transverse plate in said body portion dimensioned for sliding movement longitudinally thereof, push rod means journaled through the closed end of said body portion for reciprocal movement therethrough and fixed to said plate, push-button means slidably received in the open end of said body portion, said push-button means being provided with resilient finger-like members projecting axially therefrom along inner surface portions of said body portion into releasable connection with said plate, a plurality of electrical contact plates projecting through said closed end on either side thereof internally and ex- .ternally of said body portion, and at least one reversely arcuately folded switch blade in said housing formed from resilient material and having one end thereof fixed to define a circuit connection and the other end thereof provided with a multiple face contact thereon and freely movable between spaced inner ends of a pair of contact plates for alternate electrical connection therewith, said switch blade being positioned for camming engagement of the free end thereof by said transverse plate during move ment thereof toward said closed end to move said face contact out of engagement with one contact plate and into engagement with another, said movable free end of said switch blade forming a part of an inclined leg portion along which said transverse plate slides during switch actuation.

4. The switch assembly of claim 3 wherein a lamp unit is fixedly mounted in said body portion between said transverse plate and push-button means, the finger-like members of said push-button means sliding freely through said lamp unit during movement of said transverse plate.

5 A switch assembly of the push-button type comprising a hollow body portion of internal generally rectangular shape having an open end and a closed end, a transverse plate in said body portion dimensioned for sliding movement longitudinally thereof, push rod means journaled through the closed end of said body portion for reciprocal movement therethrough and fixed to said plate, push-button means of generally rectangular outline slidably received in the open end of said body portion, said push-button means being generally cup-shaped with a continuous transverse end wall portion joined with an axial peripheral skirt portion and connected with said plate, said skirt portion inwardly of said end wall'portion being circumferentially recessed to define a groove pposed to the inner surface portions of said body portion inwardly of said open end, a continuous sealing ring mounted in said groove and in resilient sliding sealing engagement with said inner surface portions, said sealing ring being of molded generally rectangular shape for relatively relaxed confirmation to the rectangular shape of said groove, a plurality of electrical contact plates projecting through said closed end on either side thereof internally and extemally of said body portion, and at least one resilient switch blade in said housing having one end thereof fixed to define a circuit connection and the other end thereof provided with a multiple face contact thereon and freely movable between spaced inner ends of a pair of contact plates for alternate electrical connection therewith, said switch blade being positioned for camming engagement of the free end thereof by said transverse plate during movement thereof toward said closed end to move said face contact out of engagement with one contact plate and into engagement with another.

6. The switch assembly of claim wherein said sealing ring is of generally chevron-like configuration in cross section with a base portion substantially filling said groove and a flexible lip portion angled from said groove into sealing engagement With said inner surface portions.

7. A switch assembly of the push-button type comprising'a hollow body portion of internal, generally rectangular shape having an open end and a closed end, a transverse plate in said body portion dimensioned for sliding movement longitudinally thereof, push rod mean-s journaled through the closed end of said body portion for reciprocal movement therethrough and fixed to said plate, push-button means of generally rectangular outline slidably received in the open end of said body portion, said push-button means being generally cup-shaped with a continuous transverse end Wall portion joined with an axial peripheral skirt portion and provided with resilient finger-like members projecting axially therefrom along inner surface portions of said body portion into releasable connection with edge portions of said plate, the end wall portion of said push-button means projecting from the open end of said body portion, said skirt portion inwardly of said end wall portion being circumferentially recessed to define a groove opposed to the inner surface portions of said body portion inwardly of said open end, a continuous sealing ring mounted in said groove and in resilient sliding sealing engagement with said inner surface portions, said sealing ring being of molded, generally rectangular shape for relatively relaxed confirmation to the rectangular shape of said groove, a plurality of electrical contact plates projecting through said closed end on either side thereof internally and externally of said body portion, at least one reversely arcuately folded switch blade in said housing formed from the same material and having one end thereof fixed to define a circuit connection and the other end thereof provided with a multiple face contact thereon and freely movable between spaced inner ends of a pair of contact plates for alternate electrical connection therewith, said switch blade being positioned for camming engagement of the free end thereof by said transverse plate during movement thereof toward said closed end to move said face contact out of engagement with one contact plate and into engagement with another, said movable free end of said switch blade forming a part of an inclined leg portion along which said transverse plate slides during switch actuation, and resilient means urging said transverse plate away from said closed end to release said switch blade.

8. The switch assembly of claim 7 wherein said sealing ring is of generally chevron-like configuration in cross section with a base portion substantially filling said groove and a flexible lip portion angled from said groove into sealing engagement with said inner surface portions.

9. The switch assembly of claim 7 wherein a lamp unit is fixedly mounted in said body portion between said transverse plate and push-button means, the finger-like members of said push button means sliding freely through said lamp unit during movement of said transverse plate.

References Cited in the file of this patent UNITED STATES PATENTS

Claims

1. A SWITCH ASSEMBLY OF THE PUSH-BUTTON TYPE COMPRISING A HOLLOW BODY PORTION HAVING AN OPEN END AND A CLOSED END, A TRAVERSE PLATE IN SAID BODY PORTION DIMENSIONED FOR SLIDING MOVEMENT LONGITUDINALLY THEREOF, PUSH ROD MEANS JOURNALED THROUGH THE CLOSED END OF SAID BODY PORTION FOR RECIPROCAL MOVEMENT THERETHROUGH AND FIXED TO SAID PLATE, PUSH-BUTTON MEANS SLIDABLY RECEIVED IN THE OPEN END OF SAID BODY PORTION, SAID PUSH-BUTTON MEANS BEING GENERALLY CUP-SHAPED WITH A CONTINUOUS TRANSVERSE END WALL PORTION JOINED WITH AN AXIAL PERPHERAL SKIRT PORTION AND PROVIDED WITH RESILIENT FINGER-LIKE MEMBERS PROJECTING AXIALLY THEREFROM ALONG INNER SURFACE PORTIONS OF SAID BODY PORTION INTO RELEASABLE CONNECTION WITH EDGE PORTIONS OF SAID PLATE, THE END WALL PORTION OF SAID PUSH BUTTON MEANS PROJECTING FROM THE OPEN END OF SAID BODY PORTION, SAID SKIRT PORTION INWARDLY OF SAID END WALL PORTION BEING CIRCUMFERENTIALLY RECESSED TO DEFINE A GROVVE OPPOSED TO THE INNER SURFACE PORTIONS OF SAID BODY PORTION INWARDLY OF SAID OPEN END, A CONTINUOUS SEALING RING MOUNTED IN SAID GROOVE AND IN RESILIENT SLIDING SEALING ENGAGEMENT WITH SAID INNER SURFACE PORTIONS, A PLURALITY OF ELECTRICAL CONTACT PLATED PROPJECTING THROUGH SAID CLOSED END ON EITHER SIDE THEREOF INTERNALLY AND EXTERNALLY OF SAID BODY PORTION, AND AT LEAST ONE REVERSELY ARCUATELY FOLDED SWITCH BLADE IN SAID HOUSING FORMED FROM RESILIENTLY MATERIAL AND HAVING ONE END THEREOF FIXED TO DEFINE A CIRCUIT CONNECTION AND THE OTHER END THEREOF PROVIDED WITH A MULTIPLE FACE CONTACT THEREON AND FREELY MOVABLE BETWEEN SPACED INNER ENDS OF A PAIR OF CONTACT PLATES FOR ALTERNATE ELECTRICAL CONNECTION THEREWITH, SAID SWITCH BLADE BEING POSITIONED FOR CAMMING ENGAGEMENT OF THE FREE END THEREOF BY SAID TRANSVERSE PLATE DURING MOVEMENT THEREOF TOWARD SAID CLOSED END TO MOVE SAID FACE CONTACT OUT OF ENGAGEMENT WITH ONE CONTACT PLATE AND INTO ENGAGEMENT WITH ANOTHER.