US2957970A

US2957970A - Circuit interrupting means

Info

Publication number: US2957970A
Application number: US682484A
Authority: US
Inventors: Owen L Taylor
Original assignee: Bryant Electric Co
Current assignee: Bryant Electric Co
Priority date: 1957-09-06
Filing date: 1957-09-06
Publication date: 1960-10-25
Anticipated expiration: 1977-10-25

Description

Oct. 25, 1960 Filed Sept. 6, 1957 WITNESSES ZWMM O. L. TAYLOR CIRCUIT INTERRUPTING MEANS JIIZ 2 Sheets-Sheet 1 INVENTOR Owen L.Tuylor AT rbRNEY Oct. 25, 1960 o. L. TAYLOR 2,957,970

CIRCUIT INTERRUPTING MEANS Filed Sept. 6, 1957 2 Sheets-Sheet 2 Fig.4.

United States Patent 2,957,970 CIRCUIT lNTERRUPTINGMEANS Owen L. Taylor, Easton, Conn., assignor to The Bryant Electric Company, Bridgeport, Conn., a corporation of Connecticut Filed Sept. 6, 1957, Ser. No. 682,484

23 Claims. 01. 200 -166) My invention relates generally to circuit interrupting meansfi such as switches, and more particularly to a pew and improved contact and supporting structure there- In past constructions of certain electric switches having cam operated reciprocal brushes, a brush member is generally secured to a fixed terminal and is adapted to selectively electrically and mechanically engage a pair of spaced fixed contacts. The brush is normally constructed of a resilient electrical conducting material and is secured to the terminal so that the brush is normally stressed into engagement with one of the spaced contacts with an initial contact pressure. The brush can then be moved into engagement with the other fixed contact by the operation of a cam which exerts a force on the brush sufficient to further stress the brush and move it into engagement with the other of the spaced fixed contacts. In order to maintain sufiicient contact pressure with the other -fixed contact, the brush must be further flexed by the cam after actual engagement with the other contact occurs. In view of this need to further flex the brush to obtain adequate contact pressure, major problems in material variation have been encountered in the construction of such brushes. The forces involved due to such brush fiexures are excessive and lead to a shortening in mechanical life of the operating parts and bearings. Furthermore, since the accuracy of forming the brush determines the contact pressure, close limits must be maintained in order to give adequate contact life. Variations in hardness and thickness of the standard material used in the brushes are such that gauging and adjusting operations are necessitated which result in high manufacturing costs. The conventional brush, constructed from resilient material which must be formed to maintain adequate contact pressure, is the main source of manufacturing and field difficulty.

The present invention eliminates the disadvantages of past brush constructions by providing a relatively rigid movable brush having a movable pivot point and which brush is spring loaded by means of a separate spring. The brush is operable by a cam in a manner where no brush flexing forces are encountered. This brush construction also provides sufficient contact pressure on the normally disengaged fixed contact without flexing the brush, which pressure may be made to be even greater than the contact pressure existing between the normally engaged fixed contact and the brush. Inasmuch as substantially no flexing of the brush exists, material variations in the material used for the brushes do not impair the operation of the switch, allowing a substantial reduction in manufacturing and maintenance costs and providing longer life for the switch and its associated operating parts. I g

' Accordingly, one object of my invention is to provide a cam operated wiring device having a new and improved movable contact structure. I Another object of my invention is to provide a circuit interrupting means having a pair of spaced stationary contacts and having a new and improved cam operated movable brush interacting therewith, in which contact pressure between the brush and the contacts is achieved with a minimum of wear of the moving par-ts.

Another object of my invention is to provide a circuit interrupting means having a pair of spaced stationary contacts and having a new and improved movable brush member operable to selectively engage each contact with substantially the same contact pressure therebetween.

A more particular object of my invention is to provide a switch having a pair of spaced stationary contacts and a fixed terminal, with a movable brush member located to engage said terminal and normally biased into engagement with one of the contacts, and an operating means positioned to pivotally move the brush member about a plurality of pivot points into engagement with the other of the contacts.

Another more particular object of my invention is to provide a switch having a pair of spaced stationary contacts and a fixed terminal thereon, with a movable brush member having one end thereof resting on the terminal and the other end movable to engage the contacts, a resilient means engaging an intermediate portion of the brush member to normally bias the other end thereof into engagement with one of the contacts, and an operating member positioned to engage the brush member between the other end and the one portion, whereby the operating member is operable to pivotally move the brush about a plurality of pivot points into engagement with the other contact.

These and other objects of my invention will become more apparent upon consideration of the following detailed description of a preferred embodiment thereof, when taken in conjunction with the attached drawings, in which:

Figure l is a top plan View of a switch constructed in accordance with the principles of my invention having its cover and shield removed;

Fig. 2 is a cross-sectional view of the switch shown in Fig. 1 taken along the line II--II thereof;

Fig. 3 is a cross-sectional view of the switch shown in Fig. 1 taken along the line IIIIII thereof;

Fig. 4 is a side elevation view of the terminal and brush assembly employed in the switch shown in Fig. 1;

Fig. 5 is a top plan view of the terminal and brush assembly shown in Fig. 4;

Fig. 6 is an end elevation view of the terminal structure shown in Fig. 4 and having the brush and spring portions removed;

Fig. 7 is a perspective view of the terminal and brush assembly shown in Fig. 4 and having a portion thereof cut away;

Fig. 8 is a top plan view of part of the switch structure including a part of the operating cam structure of the switch shown in Fig. 1 and shown in one operating position; and

Fig. 9 is a top plan view similar to Fig. 8 but with the parts shown in another operating position.

Referring to the drawings, it is to be noted that a switch constructed in accordance with the teachings of my invention may be mounted in an insulating casing 2, which may be of any desired electrical insulating material such as a molded phenolic insulating material. The insulating casing 2 includes a bottom wall 4, opposed side walls 6, and end Walls 8. The bottom wall 4 is provided at its inner side with a centrally located, integral, circularly raised portion 10 having a recess 12 therein for receiving an end portion 24 of an operating shaft 14. The perimeter of the raised portion 10 is provided with the ledge 16 which is adapted to abut the lower surface of a lower cam 18 in order to limit inward motion of the latter into the casing 2. The shaft 14 is also provided with an upper cam 20 spaced from the lower cam 18 by a cam spacer washer 22. The

cams

18 and 20 and the spacer washer 22 are preferably constructed of a wear resistant, electrical insulating material such as the same material comprising the casing 2, and are each provided with a central D-shaped circular opening therein which is adapted to non-rotatably receive a similarly shaped lower portion 24 of the shaft 14. The shaft 14 is provided with an intermediate portion 26 having a reduced diameter and which is adapted to receive a deformed alignment washer 28. The alignment washer 28 is preferably constructed of a material having resilient properties, such as spring steel, and may be circular in shape and concavo-convex in section. Motion of the alignment washer 28 along the shaft 14 is prevented by the difference in diameters of the intermediate portion 26 and the adjacent upper and lower portions of the shaft 14, respectively.

The alignment washer 28 acts to maintain the shaft 14 in a fixed position in the casing 2, for it is spaced from the switch cover 32 by cover spacer washers 30 and from the bottom wall 4 by

cams

18 and 20, cam washer 36 and cam spacer Washer 22. The cover 32 is preferably constructed of a metal such as sheet steel, and is provided with a centrally located opening through which the upper portion 34 of the shaft 14 may pass. Cover spacer washers 30 are slipped onto the shaft upper portion 34 and are of such diameter as to be unable to pass through the shaft opening in the cover 32.

Accordingly, the shaft 14 comprises a D-shaped lower portion 24, an intermediate portion 26 of smaller diameter than the lower portion 24 and a D-shaped upper portion 26 adjacent thereto, preferably having the same diameter as the lower portion 24. The upper shaft portion 34 may be provided with an elongated longitudinally extending slot 38 through which the shaft is engaged by an operating handle, not shown.

To assemble the described parts to the shaft, the alignment washer 28 is forced into engagement with the intermediate portion 26 of the shaft. The cam washers 36 are slipped over the end of the lower shaft portion 24 until they abut the lower surface of the alignment washer 28. The upper cam 20 and lower cam 18 are each slipped over the lower end thereof, respectively, to be located nonrotatably thereon. The cover washers 30 are slipped over the upper shaft portion 34 into engagement with the upper surface of the alignment washer 28. The lower end of the shaft 14 is then inserted into the recess 12 and the cover 32 is slipped over the upper shaft portion 34 and secured to the casing 2 by suitable means, such as by staking portions of the cover to the lower surface of ledges 40 located on each of the end walls 8 by passing suitable securing lugs integral with cover (not shown) through the passages 42 thereof.

It is, therefore, to be noted that the shaft 14 is prevented from moving longitudinally in the casing 2, for inward motion of the shaft 14 in the casing is prevented by the bottom wall 4 and outward motion thereof is by the cover 32 and interaction between the alignment washer 28 and the cover washer 30.

In each of the upper corners of the switch casing 2 (as viewed in Fig. 1) there is an abutment 44 integral with the bottom wall 4 and adjacent side 6 which extends perpendicularly to the side walls 6 of the casing at a point spaced from the adjacent end wall 8. The abutments 44 have elongated slots 46 therein to receive stationary contact supports, and these slots also extend through the bottom wall 4. The bottom wall 4 of the casing 2 is also provided with inwardly extending posts 50 at one side of the intermediate portion of each of the inner stationary contact supports 52 and 52'. Oval-shaped ridges 54 are also provided on bottom wall 4 located to be adjacent the opposite sides, respectively, of stationary contact supports 52 and 52'. The upper end wall 8 is provided with a pair of spaced extensions 56 adjacent each of the inner contact supports 52 and 52 which extensions cooperate with the posts 50 and oval ridges 54 to receive and locate the inner contact supports 52 and 52', respectively, in the casing.

In the present embodiment of this invention, the switch is provided with one stationary contact support 48 in the upper left-hand corner and the two inner contact supports 52 and 52' previously mentioned. It is to be noted, however, that the housing 2 is formed to receive another stationary contact support in the upper right-hand corner thereof in a manner similar to the mounting of contact support 48.

The contact support 48 is an elongated flat member of an electrical conducting material such as copper or a copper alloy, and has a contact 49, also of a good electrical conducting, arc-resistant material, such as silver or a silver alloy, mounted thereon by suitable means, such as by brazing. The support 48 is provided with a laterally extending coplanar terminal portion 58 thereon whichpasses through the slot 46 to the exterior of the casing 2. The terminal portion 58 is provided with portions 60 at opposite sides which are deformed to stake the contact support 42 to the bottom wall 4, and which cooperate with the abutment 44 to firmly secure the contact support 48 in position.

The inner contact support 52 is constructed of the same.

material as contact support 48 and is provided with a contact 62, also comprised of a material having good electrical conducting and arc-resisting properties such as the same material used for contact 49. The support 52 has one end located in the space between the wall extensions 56 and has another portion thereof passing through the opening between the post 50 and oval ridge 54. The bottom wall 4 is provided with a passage therein, through which terminal portion 58A passes through the casing, and terminal portion 58A is secured to the housing by. staking of the lugs 60 thereon in a manner similar to that provided for contact support 48. A similar contact support 52 is located on the other side of the casing and is mounted in its casing in the same manner as contact support 52.

Mounted in each of the lower corners of the casing 2 (as viewed in Fig. l) are fixed L-shaped terminal supports 64 comprising stem portions 63 and base portions 65, preferably constructed of the same material as contact supports 48, 52 and 52' and provided with coplanar ter-, minals 58B extending laterally from the stem 63 thereof and secured to the housing by staked lugs 68 thereon in the manner previously described.

Referring specifically to Figs. 4 through 7, it is to be noted that the terminal support 64 is provided with an elongated slot 66 which extends through a portion of the stem 63 and the base 65 thereof, respectively, and which terminates in a portion 67 of lesser width than the slot 66. A pair of elongated brushes 68 of a width slightly less than the width of slots 66 are each provided with a pair of oppositely spaced mounting notches 78 in opposite sides adjacent one end thereof. Each brush 68 is preferably constructed of the same material as contact support 48 and is assembled to the terminal support 64 by passing the notched end thereof through the slot 66 and moving the notched portion into the slot portion 67. The notches 70 are of a width considerably greater than the thickness of the terminal 64 so that the brush is pivotally movable about its notched end, and the notched end is also movable in the plane of the base 65 of the terminal support 64, Longitudinal motion of the brushes 68 is prevented by interaction of the notched end of brush 68 and slot portion 67. The upper portion of the stem 63 of the terminal 64 is provided with a pair of spaced openings 72. A 'U-shaped leaf spring 7-4,v constructed from a thin resilient electrical conducting material such as a copper alloy, is provided having the free ends bent laterally out: wardly with each end having a pair of spaced aligned lugs 75 extending outwardly. One pair of lugs 75 extends into the aligned openings 72 in stem 63 of the terminal support 64, and the other pair of lugs are located in aligned slots 76 located on opposite sides of an intermediate portion of the brush 68. The spring 74 is assembled with the brush and terminal structures so that the biaht portion thereof extends through slot 66 in the terminal support 64. The brush 68, when assembled to the terminal support 64, extends essentially parallel to the side walls 6 of the casing 2 and is provided with contacts 85 symmetrically secured on opposite sides thereof and normally in engagement with the inner fixed contacts, such as 62, with a contact pressure, the magnitude of which is discussed hereinafter. f

With reference to the showing of the brush 68 on the left-hand side of Fig. '1, it is to be' noted that it is provided with centrally located laterally oppositely struck-out portions 78 and 88 between the slots 76 and contacts 85. The struck-out portion 78 is located on the lower half of the brush and extends inwardly of the oppositely struckout portion 80, located on the upper half thereof. Likewise, in the showing of the right-hand brush of Fig. 1, similar struck-out portions exist but are diiferent from those of the left-hand brush in that the struck-out portion 78 is located on the upper half of the brush and the portion 80 on the lower half thereof. The struck-out portions 78 of each brush 68 are located to be engaged by one of the

cams

18 or 20 so that the brush 68 is pivotally movable thereby from its normal rest position by rotation of the shaft 14. As shown in Figure 2, the left-hand brush is operable by lower cam 18 while the right-hand brush is operable by upper cam 20. Since the cams are separated by the spacer washer 22, only one cam may operate one brush. The lower cam 18 which operates the left-hand brush is generally circular in cross section, but is provided with a high surface 82 and a low surface 84 thereon so that when the struck-out portion 78 thereof is in engagement with the circular circumference of the cam 18, the brush is held in an intermediate open circuit position spaced between the

stationary contacts

49 and 62, as shown in Fig. 1. When the struck-out portion 78 of left-hand brush 68 is in engagement with the high surface 82, the brush 68 is moved into engagement with the contact 49 (Fig. 9), and when the struck-out portion 78 is opposite the low surface 84 of lower cam 18, the lefthand brush 68 is in engagement with contact 62 as shown in Fig. 8.

The upper cam is provided with a low surface 83 so that the right-hand brush 68 is in engagement with fixed contact 62 when the shaft 14 is rotated so that low surface 83 is facing the right-hand brush 68.

As hereinbefore described, the spring 74 is assembled with the brush and terminal structures by locating one pair of end lugs 75 in openings 72 in terminal support 64 and by locating the other pair of lugs 75 in aligned slots 76 of brush 68. Spring 74 is thereby stressed to bias contact 85 into engagement with stationary contact 62 and also to bias the notched end of brush 68 into engagement with the edge of slot portion 67 of terminal support 64. The contact pressure at both ends of brush 68 is determined by the force exerted by spring 74 and the location of the latter along brush 68.

It is to be noted that the contact pressure between the brush 68 and contact 62 (Fig. 8) is at least equal to the contact pressure between brush 68 and contact 49. This may easily be seen upon consideration of the forces involved. The contact pressure P as shown in Fig. 8 is equal to:

A A+B+C (I) where P is the contact pressure between

contacts

85 and 62,

respectively.

F is the spring force exerted by the leaf spring 74 on brush 68.

A is the distance between notches 70 of the brush 68 and the'slots 76 thereof; and

A-+B-|-C is the effective length of the brush between notches 70 and contact 85.

The contact pressure P exerted on contact 49 by brush 68 as shown in Fig. 9 is given by the equation:

where F gis the spring force exerted on brush 84, as shown in B is the distance between the struck-out portion 78 of brush 68 and the point of engagement of spring 74 with the brush 68, and

C is the distance between struck-out portion 78 and con.-

tact thereof.

Accordingly, it is to be noted that if the magnitude of the ratio of distances A l t B the pressure P will be greater than P for F is greater than F The latter is true because leaf spring 74 exerts force F equivalent to F 5 16. 6

where k is the modulus of spring 74, and x is the deflection of spring 74. Since the deflection of spring 74 in the position shown in Fig. 9 is greater than the deflection of the spring in the position shown in Fig. 8,

The influence of the spring force F and the location of spring 74 along brush 68 on the pressure between the notched end of brush and the edge of slot portion 67 can be seen by calculating the moments about the brush contact 85 in the position shown in Fig. 8 and which results in FBXA mm 5) where P =contact pressure between the notched brush end and the edge of slot extension 67.

It can therefore be seen that the magnitude of pressure P may be varied by varying the magnitude of spring force F or by varying the magnitude of the ratio of distances A/A+B+C.

Referring specifically to Fig. 9, the brush 68 is not flexed by the high surface 82 of the cam, for the slotted end of the brush is movable in the plane of the base 65 of terminal support 64. It is therefore to be noted that the brush in this position acts as a first-class lever, for brush 68 acts as a rigid body, high surface 82 provides a fulcrum, contact pressure P between

contacts

85 and 46 provides a force on one side of the fulcrum, and spring 74 located on the opposite side of the fulcrum exerts another force P for the lever system. Since spring 74 is preferably constructed of a thin material, its ends form substantially knife edges under contact pressure with the brush 68 and terminal Support, respectively, also determined in magnitude by spring forces F and F Electrical current may then pass from contact 49 to contact 85 of brush 68 held in engagement under pressure P Current then flows from brush 68 to spring 74 and from spring 74 to terminal 64 at thepoint of engagement of the essentially knife-edged end of the spring located adjacent lugs 75. It is therefore notable that spring 74 serves a dual purpose in that it provides adequate con,- tact pressure for brush 68 as well as being a portion of the electricalconducting circuit. 4

When brush 68 is in engagement with contact 62, as shown in Fig. 8, the brush acts as a third-class lever system, for base 65 of terminal support 64 is the fulcrum, spring 74 provides a force F at a point spaced from the fulcrum along brush 68, and P further spaced from.

the fulcrum along brush 68, provides another force for the system. The electrical circuit in this instance is obtained'between brush 68 and contact 62 held in engagement by the contact pressure P and current flows to terminal support 64 through the substantially knife-edged ends of spring 74, and through the slotted end of brush 68 at slot extension 67.

The change in the lever systems from first to third class can most easily be seen by a description of the operation of the switch. When the cams are in the posi-. tion shown in Fig. 1, the switch is at its off position, for no electrical contact is made by the left and righthand brushes 68 and the fixed

contacts

49, 62 and 62, respectively. The brush structure in this instance provides a third class lever system, for base 65 of terminal support 64 acts as the fulcrum, spring 74 provides a force at a point spaced from the fulcrum along brush 68, and another force for the system is provided at the point of engagement of each of the struck-out portions 78 against the normal circumference of the operating

cams

18 and 20, respectively. When shaft 14 is rotated 90 clockwise, the left-hand brush 68 is brought into engagement with fixed contact 49 with contact pressure as defined by Equation 2. As previously pointed out, this system then becomes a first-class lever system. It is to be noted that as the high cam surface 82 commences to engage struckout portion 78, the brush 68 is pivotally moved about its notched end until such pivotal motion is stopped by the engagement of contact 85 of brush 68 with stationary contact 49. At that time the fulcrum of the lever system changes from the notched end of brush 68 to contact 85. As the rotation of the cam is continued, pivotal motion of brush 68 continues about the new fulcrum at contact 85, and the notched brush end is moved along slot portion 67 until the center of high surface 82 directly opposes struck-out portion 78. The slot portion 67 is constructed of such length as to keep the notched brush end located therein during motion of the latter along slot 67. As rotation of shaft 14 continues beyond 90", a reduced portion of high surface 82 initially engages struck-out portion 78, and the brush 68 pivotally moves about contact 85 until the motion of the notched brush end is stopped by the outer edge of slot extension 67. At this point the slotted end of brush 68 again becomes a fulcrum in the lever system, and the lever system returns to a third class system. Pivotal motion of brush 68 continues then about the notched end thereof until the circular surface of cam 18 engages struck-out portion 78. During such motion of shaft 14, right-hand brush 69 remains in'an open circuit position, for it remains in engagement with the normal circumference of cam 20.

When shaft 14 is rotated another 90 in a clockwise direction, low surface 84 engages struck-out portion 78 of the left-hand brush (Fig. 8). Such engagement causes brush 68 to pivotally move about its notched end until the pivotal motion is stopped by the engagement of contacts '85 and 62, respectively. The contact pressure between movable contact 85 and fixed contact 6-2 in this instance is defined by Equation 1. Right-hand brush 68 is still engaged by the circular surface of cam 20 and remains in an open circuit position during such rotation. When shaft 14 is rotated still another 90 clockwise, low surface 83 of cam 20 engages struck-out portion 78 of the right-hand brush 68 causing the latter to pivotally move about its notched end until it is brought into engagement with fixed contact 62 and having contact pressure defined by Equation 1. Left-hand brush 68 then returns to an open circuit position, for its struck-out portion 78 is engaged by the circular surface of cam 18.

It is therefore to be noted that by providing a brush member having its notched'end movable along the base of the terminal and having an external spring for normally biasing the brush into engagement with one of the stationary contacts, my invention provides for the engagement of the other stationary contact by the brush with at least the same contact pressure as that obtained between the brush and the normally engaged stationary contact. I have also insured good contact pressure between the terminal member and the brush by placing the spring in the electrical circuit and by also providing for the spring to bias the brush into engagement with the terminal when the brush engages the normally engaged stationary contact. By the provision of a notched end of the brush, I have insured against longitudinal motion of the brush and have thereby provided an easily assembled switch structure where the parts are merely placed in position without the necessity of additional securing means.

Having now described the invention, the construction, operation and use of a preferred embodiment thereof, the new and useful results obtained thereby, it is to be realized that numerous changes may be made in the above described construction and different embodiments of my invention may be made without departing from the spirit and scope thereof. Accordingly, it i intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted .as illustrative and not in a limiting sense.

I claim as my invention:

1. A switch structure comprising, a support, an elongated movable member, means for engaging said movable member with said support so that one end of said movable member is movable lirnitedly along said support but substantially not movable outwardly of said support, a pair of spaced stationary contacts located to be engaged by the other end of said movable member in response to movement thereof in opposite directions, resilient means engaging one intermediate portion of said movable member to bias normally said other end into engagement with one of said contacts and said one end into one limited position along said support, an operating member positioned to engage another portion of said movable member located between said other end and said one portion of said movable member, said operating member being movable to cause said other end of said movable member to move into engagement with the other of said contacts and thereafter to cause said one end of said movable member to move along said support away from said one limited position, whereby the contact pressure between said contacts and said other end is determined by the location of said resilient means along said movable member.

2. A switch structure comprising, a support of insulating material, a terminal member having a slot therein and being secured to said support, an elongated movable brush having one end thereof located in said slot, said one end being shaped so that it is movable only along said slot, a pair of spaced stationary contacts located to be engaged by the other end of said brush, in response to movement thereof in opposite directions, electrically conducting resilient means having a knife edge which engages one intermediate portion of said brush to normally bias said other end into engagement with one of said contacts and said one end into engageent with one end of said slot, an operating member positioned to engage another portion of said brush located between said other end and said one portion of said brush, said operating member being movable to cause said other end of sadi brush to move into engagement with the other of said contacts and thereafter to cause said end of said brush to move along said slot away from said one end thereof, whereby the contact pressure between said contacts and said other end is determined by the location of said resilient mean along said movable member.

3. A switch comprising, a support of insulating material, an L-shaped terminal member having base and stem portions, said base portion having an elongated slot therein, an elongated movable brush having one end thereof located saidslot, a pair of spaced stationary contacts located to be engaged by the other end of said brush inresponse to-movement thereof in opposite directions, resilient means having its ends engaging said stem portion and one intermediate portion of said brush, respectively, to normally bias said other; end of said brush into engagement with one of said contacts and said one end thereof into engagement with one end of said slot, an operating member positioned to engage another portion of said brush located between said other end and said one portion of said brush, said operating member being operable to move said other end of said brush into engagement with the other of'said contacts and thereafter to move said one end of said brush along said slot away from said one end thereof, where by the contact pressure between said contacts and said other end is determined by the location of said resilien means along said movable member. I 4. A switch comprising, a support of insulating material, an L-shaped terminal member havingbase and stem portions, said base portion having an elongated slot therein, an elongated movable brush having one end thereof located in said slot, a pair of spaced stationary contacts located to be engaged by the other end of said brush in response to movement thereof in opposite directions, essentially U-shaped resilient means having the end of one arm thereof in engagement with said terminal member and having the end of the other arm there of engaging one intermediate portion of said brush to normally bias said other end of said brush into engagement with one of said contacts and said one end into engagement with said terminal, an operating member positioned to engage another portion of said brush located between said other end and said one portion of said'brush, said operating member being movable to 'cause said other end of said brush to move into engagement with the other of said contacts and thereafter to cause said one end of said brush to move away from said terminal along said slot, whereby the contact pressure between said contacts and said other end is determined by the location of said resilient means along said movable member.

5. A switch structure comprising, a support, an elongated movable member, means for engaging said movable member with said support so that one end of said movable member is movable limitedly along said support but substantially not movable outwardly of said support, a pair of stationary contacts located to be engaged by the other end of said movable member in response to movement thereof in opposite directions, resilient means engaging one intermediate portion of said movable member to bias normally said other end into engagement with one of said contacts and said one end into one limited position along said support, an operating member positioned to engage another portion of said movable member located between said other end and said one portion of said movable member, said operating member being movable to cause said other end of said movable member to move pivotally about said one end into engagement with the other of said contacts and thereafter to cause said one end of said movable member to move pivotally about said other end along said support away from said one limited position, whereby the contact pressure between said contacts and said other end is determined by the location of said resilient means along said movable member.

6. A switch comprising, a support of insulating material, an L-shaped terminal member having base and stem portions, said base portion having an elongated slot therein, an elongated movable brush having one end thereof located in said slot, a pair of spaced stationary contacts located to be engaged by the other end of said brush in response to movement thereof in opposite di- Iec'tions, an essentially Ll-shaped resilient 'leaf' spring, said springflhaving, one arm in engagement with said 10 terminal stern and the bight portion thereof passing through said slot in said terminal base portion, the other spring arm engaging one intermediate portion of said brushto normally bias said other end into engagement with one of said contacts and said one end into engagement with said terminal, an operating member positioned to engage another portion of said brush located between said other end and said one portion of said brush, said operating member being operable to move said other end of said brush into engagement with the other of said contacts and thereafter to move said one end of said brush away from said terminal along said slot, whereby the contact pressure betweensaid contacts and said other end is determined by the location of said spring along said movable member. 1

7. A switch comprising, a support of insulating material, an L-shaped terminal member having base and stem portions, said base portion having an elongated slot therein, said slot having a portion of lesser width at one end thereof, an elongated movable brush having a pair of opposed notches located in opposite sides thereof adjacent one end, said-notches being located in said slot portion to prevent longitudinal motion of said brush, a pair of spaced stationary contacts located to be engaged by the-other end of said brush in response to movement thereof in opposite directions, resilient means having its ends engaging said stern and one intermediate portion of said brush, respectively, to normally bias said other end of said brush into engagement with one of said contacts and said one end thereof into engagement with said one slot end, an operating member positioned to engage another portion of said brush located between said other end and said one portion of said brush, said operating member being operable to move said other end of said brush into engagement with the other of said contacts and thereafter to move said one end of said brush along said slot away from said one end thereof, whereby the contact pressure between said contacts and said other end is determined by the location of said resilient means along said movable member.

8. A switch structure comprising, a support, an elongated electrically conductive movable member, means for engaging said movable member with said support so that one end of said movable member is movable limitedly along said support but substantially not movable outwardly of said support, a stationary contact located to be engaged by the other end of said movable member, electrically conductive resilient means having a knife edge which engages one intermediate portion of said movable member to bias normally said other end into engagement with said contact and said one end into one limited position along said support, an operating member positioned to engage another portion of said movable member located between said other end and said one portion of said movable member, said operating member being operable to move said other end of said movable member away from said contact substantially without flexing said movable member.

a 9. A switch structure comprising, a support, an elongated movable member, means for engaging said movable member with said support so that one end of said movablemember is movable limitedly along said support but substantially not movable outwardly of said support, a stationary contact located to be engaged by the other end of said movable member, resilient means engaging one intermediate portion of said movable memher to bias normally said movable member into engagement with an operating member and said one end into one limited position along said support, said operating member being positioned to engage another portion of said movable member located between said other end and said one portion of said movable member and movable to cause said other end of said movable member to move into engagement with said contact and thereafter to cause said one end of said movable member to move along said support away from said one limited position, whereby the contact pressure between said contact and said other end is determined by the location of, said resilient means along said movable member.

10. A switch structure comprising, a support of insulating material, a terminal member havinga slot therein and being secured to said support, an elongated movable brush having one end thereof located in said slot, a stationary contact located to be engaged by the other end of said brush, resilient means engaging one intermediate portion of said brush to normally bias said brush into engagement with an operating member and said 0, 6 end into engagement with one end of said slot, said operat: ing member being positioned to engage another portion of said brush located between said other end and said one portion of said brush and movable to cause said other end of said brush to move into engagement with said contact and thereafter to cause said one end of said brush to move along said slot away from said one end thereof.

11. A switch comprising, a support of insulating ma terial, a terminal member having angularly related base and stem portions, said base portion having an elongated slot therein, said slot having a portion of lesser width at one end thereof, an elongated movable brush having one end of a width less than the width of said slot but greater than the width of said slot portion and having a pair of opposed notches in opposite sides thereof adjacent said one end, said notches being located in said slot portion to prevent longitudinal motion of said brush, a stationary contact located to be engaged by the other end of said brush, resilient means having its ends engaging said stem and one intermediate portion of said brush, respectively, to normally bias said other end of said brush into engagement with said contact and said one end thereof into engagement with said one slot end, an operating member positioned to engage another portion of said brush located between said other end and said one portion of said brush, said operating member being operable to move said other end of said brush away from said contact.

12. A switch comprising, a support of insulating material, a terminal member having angularly related base and stem portions, said base portion having an elongated slot therein, said slot having a portion of lesser width at one end thereof, an elongated movable brush having one end of a width less than the width of said slot but greater than the width of said slot portion and having a pair of opposed notches in opposite sides thereof adjacent said one end, said notches being locatedin said slot portion to prevent longitudinal motion of said brush, a stationary contact located to be engaged by the other end of said brush, resilient means having its ends engaging said stem and one intermediate portion of said brush, respectively, to normally bias said brush into engagement with an operating member and said one end thereof into engagement with said one slot end, said operating member being positioned to engage another portion of said brush located between said other end and said one portion of said brush and operable to move said other end of said brush into engagement with said con tact and thereafter to move said one end of said brush along said slot away from said one end thereof whereby the contact pressure between said contact and said other end is determined by the location of said resilient means along said movable member.

13. A switch structure comprising, terminal member having an elongated slot therein, said slot having a portion of lesser width at one end thereof and having a pair of spaced openings therein, an elongated movable brush having at least one end of a width less than the width of said slot but greater than the width of said slot portion and having a pair of opposed notches in opposite sides thereof adjacent said one end, said notches being located in said slot portion to prevent longitudinal motion of said brush, a pair of opposed second'notches located on opposite sides of an intermediate portion of said brush, a resilient leaf spring having essentially knife edges at opposite ends and having one end provided with a pair of projections fitting into the openings in said terminal, and having another pair of projections at its opposite end located in said second notches in said brush, respectively, by stressing said spring, whereby said structure is held in assembled relation by locating said spring projections in said openings and said second notches respectively.

14. A switch structure comprising, a terminal member having an elongated slot therein, said slot having a portion of lesser width at one end thereof, an elongated movable brush having at least one end of a width less than the width of said slot but greater than the width of said slot portion and having a pair of opposed notches in opposite sides thereof adjacent said one end, said notches being located in said slot portion to prevent longitudinal motion of said brush, resilient means stressed to have its ends engaging said terminal members and an intermediate portion of said brush, respectively, interfitting means on said terminal member, said intermediate brush portion and said spring end to hold said spring in engagement therewith and thereby hold said structure in assembled relation.

15. A switch structure comprising, a support, an elongated movable member having one end thereof resting on said support, a stationary contact located to be engaged by the other end of said movable member, an essentially U-shaped resilient electrical conducting spring having knifed edges at each end and having the end of one arm thereof in engagement with said support and the end of the other arm engaging one intermediate portion of said movable member to normally bias said other end into engagement with said contact and said one end into engagement with said support, an operating member positioned to engage another portion of said movable member located between said other end and said one portion of said movable member, said operating member being operable to move said other end of said movable member away from said contact.

16. A switch structure comprising, a support, an elongated movable member having one end thereof resting on said support, a stationary contact located to be engaged by the other end of said movable member, an essentially U-shaped resilient electrical conducting spring having knifed edges at each end and having the end of one arm thereof in engagement with said support and the end of the other arm engaging one intermediate portion of said movable member to bias said movable member into engagement with an operating member and said one end mto engagement with said support, said operating member being positioned to engage another portion of said movable member located between said other end and said one portion of said movable member and movable to cause said other end of said movable member to move into engagement with said contact and thereafter to cause said one end of said movable member to move away from said support, whereby the contact pressure between said contact and said other end is determined by the location of said resilient means along said movable member.

17. A switch structure comprising, a terminal member having an elongated slot therein, said slot having a portion of lesser width at one end thereof and having a pair of spaced openings therein, an elongated movable brush having at least one end of a width less than the width of said slot but greater than the width of said slot portion and having a pair of opposed notches in opposite sides thereof adjacent said one end, said notches being located in said slot portion to prevent longitudinal motion of said brush and spring means engaging said terminal and said brush to bias said brush in one direction.

18. A switch structure comprising, a terminal member having a pair of spaced openings therein, an elongated ASP 13 movable brush having one end thereof resting on said terminal, means to prevent longitudinal motion of said brush, a pair of opposed notched located on opposite sides of an intermediate portion of said brush, a resilient leaf spring having essentially knife edges at opposite ends and having one end provided with a pair of projections fitting into the openings in said terminal, and having another pair of projections at its opposite end located in said notches in said brush, respectively, by stressing said spring, whereby said structure is held in assembled relation by locating said spring projections in said openings and said notches respectively.

19. A wiring device comprising, a support member having an integral extension extending laterally outwardly from one side thereof, an elongated movable contact having one end thereof mounted on said support member and extending laterally outwardly from the same side of said support member as said extension, and resilient means reacting between said extension and said movable contact to bias the latter laterally.

20. A wiring device comprising, a support member, a movable contact member, means for pivotally mounting said movable contact member on said support member comprising at least one slot in one of said members and a projection on the other of said members, said slot interfitting with said projection and formed to maintain engagement of said members and to prevent relative movement of said members at their point of engagement except movement of one of said members along said slot.

21. A wiring device comprising, a support member, a movable contact member, means for pivotally mounting said movable contact member on said support member comprising at least one slot in one of said members and a projection on the other of said members, said slot interfitting with said projection and formed to maintain engagement of said members and to prevent relative movement of said members at their point of engagement except movement of one of said members along said slot and resilient means reacting between said members to bias said movable contact member laterally about said point of engagement to resist said last mentioned relative move ment.

22. A wiring device comprising, a support member, a movable contact member, means for pivotally mounting said movable contact member on said support member comprising at least one slot in one of said members and a projection on the other of said members, said slot interfitting with said projection and formed to maintain engagement of said members and to prevent relative movement of said members at their point of engagement except movement of one of said members along said slot and resilient means reacting between said members to bias said movable contact member laterally about said point of engagement to resist movement of one of said members along said slot and to encourage pivotal movement of said movable member in one direction.

23. A wiring device comprising, a support member, a movable contact member, means for pivotally mounting said movable contact member on said support member comprising at least one slot in one of said members and a projection on the other of said members, said slot interfitting with said projection and for-med to maintain engagement of said members and to prevent relative movement of said members at their point of engagement except movement of one of said members along said slot, resilient means reacting between said members to bias said movable contact member laterally about said point of engagement to resist movement of one of said members along said slot and to encourage pivotal movement of said movable member in one direction and cam means positioned to engage said movable member to limit the aforesaid pivotal movement.

References Cited in the file of this patent UNITED STATES PATENTS