LEVER OPERATED SWITCH WITH TILTABLE CONTACT ACTUATOR AND FLEXIBLE CONTACTS
United States Patent 3591747
A lever operated electric switch has a rocker that is tilted to one side or the other from an intermediate neutral position by movement of the lever. The rocker engages one arm or the other of a leaf spring type of contact member causing engagement with one or another fixed contact. The ends of the arms are reversely bent doubly into S-sahpe so that the extremity presents a longitudinal surface which wipes over the fixed contact surface. The ends are also bifurcated and laterally dished into trough shape.
US Patent References:
/1130994.html
Metzger - March 1915 - 1130994
Snap switch
Snell - September 1933 - 1925612
Lock switch
Poliakoff - July 1948 - 2445635
Momentary contact electric switch
Smith - February 1952 - 2587399
Circuit controller
Colautti - October 1959 - 2909624
/1130994.html
Metzger - March 1915 - 1130994
Snap switch
Snell - September 1933 - 1925612
Lock switch
Poliakoff - July 1948 - 2445635
Momentary contact electric switch
Smith - February 1952 - 2587399
Circuit controller
Colautti - October 1959 - 2909624
Application Number:
04/888294
Publication Date:
07/06/1971
Filing Date:
12/29/1969
View Patent Images:
Export Citation:
Assignee:
Arrow-Hart, Inc. (Hartford, CT)
Primary Class:
Other Classes:
200/559
International Classes:
H01H1/18; H01H23/12; H01H23/16; H01H1/12; H01H23/00; H01H3/00
Field of Search:
200/6,49,61.27,6B,146,144,153.10,154,159,164,166F,6--164
US Patent References:
Primary Examiner:
Hirshfield, Milton O.
Assistant Examiner:
Weldon, Ulysses
Claims:
What I claim is
1. An electric switch comprising insulation casing means, a movable operating member supported from said casing means, fixed contact means mounted in said casing means, movable leaf spring contact means mounted in said casing means adapted to engage and disengage said fixed contact means as said operating member is moved, a pivoted actuating member independent of said movable contact means and mounted in said casing means and tiltable by movement of said operating member to cause engagement and disengagement of said fixed contact means by said movable contact means, said leaf spring means being reversely bent and its end portion being curved laterally into troughlike form with its convex side positioned to engage said fixed contact means to localize pressure and prevent scoring of said fixed contact means.
2. A switch as claimed in claim 1 wherein the transverse dimension of the leaf spring means is lessened at the area of said reverse bend to facilitate flexure pivoting thereat of the remainder of said reversely bent end portion.
3. An electric switch comprising insulation casing means, a movable operating member supported from said casing means, fixed contact means mounted in said casing means, movable leaf spring contact means mounted in said casing means adapted to engage and disengage said fixed contact means as said operating member is moved, a pivoted actuating member independent of said movable contact means and mounted in said casing means and tiltable by movement of said operating member to cause engagement and disengagement of said fixed contact means by said movable contact means, said leaf spring means being reversely bent adjacent one end, the extremity of said one end being bifurcated and each bifurcation being curved laterally into troughlike form with its convex side engaging the fixed contact means to localize contact pressure and prevent scoring of the fixed contact means.
4. A switch as claimed in claim 3 wherein the transverse dimension of the leaf spring means is lessened at the area of said reverse bend to facilitate flexure pivoting thereat of the remainder of said reversely bent portion.
5. An electric switch comprising insulation casing means, a movable operating member supported from said casing means, fixed contact means mounted in said casing means, movable flexible leaf spring contact means mounted in said casing means adapted to engage and disengage said fixed contact means as said operating member is moved, a pivoted actuating member independent of said movable contact means and mounted in said casing means and tiltable by movement of said operating member to cause engagement and disengagement of said fixed contact means by said movable contact means, said leaf spring means being bent into S-shape adjacent its end portion and positioned to engage and wipe over said fixed contact means from initial to full pressure engagement.
6. A switch as claimed in claim 1 having electrically conductive means fixedly securing said leaf spring contact means adjacent its middle on said casing means with portions of the leaf spring on opposite sides of said securing means constituting separate movable contact arms, each having S-shaped end portions.
7. A switch as claimed in claim 5 wherein the transverse dimension of the leaf spring contact means is lessened at the first of the bends of the S-formation to facilitate flexure pivoting threat of the remainder of the S-formation.
8. A switch as claimed in claim 5 wherein the extremity of said leaf spring means is bifurcated and the bifurcations separately engage and press on said fixed contact means and wipe over the latter from initial to full pressure engagement.
9. A switch as claimed in claim 8 wherein the transverse dimension of the leaf spring contact means is lessened at the first of the bends of the S-formation to facilitate flexure pivoting thereat of the remainder of the S-formation.
1. An electric switch comprising insulation casing means, a movable operating member supported from said casing means, fixed contact means mounted in said casing means, movable leaf spring contact means mounted in said casing means adapted to engage and disengage said fixed contact means as said operating member is moved, a pivoted actuating member independent of said movable contact means and mounted in said casing means and tiltable by movement of said operating member to cause engagement and disengagement of said fixed contact means by said movable contact means, said leaf spring means being reversely bent and its end portion being curved laterally into troughlike form with its convex side positioned to engage said fixed contact means to localize pressure and prevent scoring of said fixed contact means.
2. A switch as claimed in claim 1 wherein the transverse dimension of the leaf spring means is lessened at the area of said reverse bend to facilitate flexure pivoting thereat of the remainder of said reversely bent end portion.
3. An electric switch comprising insulation casing means, a movable operating member supported from said casing means, fixed contact means mounted in said casing means, movable leaf spring contact means mounted in said casing means adapted to engage and disengage said fixed contact means as said operating member is moved, a pivoted actuating member independent of said movable contact means and mounted in said casing means and tiltable by movement of said operating member to cause engagement and disengagement of said fixed contact means by said movable contact means, said leaf spring means being reversely bent adjacent one end, the extremity of said one end being bifurcated and each bifurcation being curved laterally into troughlike form with its convex side engaging the fixed contact means to localize contact pressure and prevent scoring of the fixed contact means.
4. A switch as claimed in claim 3 wherein the transverse dimension of the leaf spring means is lessened at the area of said reverse bend to facilitate flexure pivoting thereat of the remainder of said reversely bent portion.
5. An electric switch comprising insulation casing means, a movable operating member supported from said casing means, fixed contact means mounted in said casing means, movable flexible leaf spring contact means mounted in said casing means adapted to engage and disengage said fixed contact means as said operating member is moved, a pivoted actuating member independent of said movable contact means and mounted in said casing means and tiltable by movement of said operating member to cause engagement and disengagement of said fixed contact means by said movable contact means, said leaf spring means being bent into S-shape adjacent its end portion and positioned to engage and wipe over said fixed contact means from initial to full pressure engagement.
6. A switch as claimed in claim 1 having electrically conductive means fixedly securing said leaf spring contact means adjacent its middle on said casing means with portions of the leaf spring on opposite sides of said securing means constituting separate movable contact arms, each having S-shaped end portions.
7. A switch as claimed in claim 5 wherein the transverse dimension of the leaf spring contact means is lessened at the first of the bends of the S-formation to facilitate flexure pivoting threat of the remainder of the S-formation.
8. A switch as claimed in claim 5 wherein the extremity of said leaf spring means is bifurcated and the bifurcations separately engage and press on said fixed contact means and wipe over the latter from initial to full pressure engagement.
9. A switch as claimed in claim 8 wherein the transverse dimension of the leaf spring contact means is lessened at the first of the bends of the S-formation to facilitate flexure pivoting thereat of the remainder of the S-formation.
Description:
This invention relates to electric switches and more particularly to lever operated switches wherein contact engagement and separation are accomplished by tilting of an actuating member or rocker as the lever is manipulated.
In prior tilt-type switches, stamped sheet metal parts were often used for the movable contacts which were rigid and tended to pit and burn and become rough and uneven after long use. Lacking adequate wiping action between the fixed and movable contact faces, the life and performance of the switch was adversely affected. Difficulties also occurred at the midpoint or central terminal support of the movable contact where dirt and burrs could affect the conductivity of the connection even if the fixed and movable contacts remained clean and smooth.
It is an object of this invention to provide a lever operated tilt-type switch mechanism in which the movable contact has a fixed and permanent support that is not affected by dirt, burrs and foreign matter and which also possesses ability of the movable contact to press on and wipe over the fixed contact surface to keep the contacts clean, smooth and bright.
Other objects and advantages of the invention will appear as it is described in connection with the drawings.
According to the present invention, a pivoted lever is mounted for operation manually to cause tilting of an actuating member or rocker within a casing to cause engagement of one set of contacts or another as the actuating member is rocked into one position or another from an intermediate neutral position. The actuating member acts on flexible leaf type movable contact members which are normally self-biased into open-circuit position. The end portion of each movable contact is of S-shape and its extremity wipes over a fixed contact as engagement between them takes place, the extremity being bifurcated and each bifurcation being laterally curved, throughout its length into trough shape for self-adjustment and for optimum contact pressure over the length of the bifurcation.
In the drawing
FIG. 1 is a longitudinal section view through a switch embodying the invention.
FIG. 2 is a plan view looking into the switch casing of FIG. 1 with the cover, operating lever and rocker removed.
FIG. 3 is a plan view of a movable switch contact as used in FIG. 1.
FIG. 4 is an end view of the movable switch contact as used in FIG. 1.
FIG. 5 is a perspective view of the contact actuating member or rocker.
Referring to the drawings, the movable and current carrying parts of the device are mounted and housed in a hollow molded insulation casing 10 of generally rectangular shape with an open top covered by a flat rectangular plate 12 of stamped or molded insulation or the like. In the floor of the casing near opposite ends fixed switch contacts 14 and 16 are mounted. The fixed contacts preferably have circular disclike heads from which a round stem portion 14s and 16s extend down through round holes in the floor of the casing. However, other types of stems may be employed of such form and shape that conductor wires can be connected to them as terminals.
The fixed contacts are each engaged alternately by arms 21 and 23 of a movable switch contact member 20 stamped from highly conductive thin sheet metal as a strip which is of generally widespread V-shape. The movable contact is secured at its center upon a platform 10' on the floor of the casing by a conductive rivet and terminal member 22 passing therethrough and having a shank 22s passing through the platform and floor of the casing 10 midway between the fixed contacts 21 and 23. The platform 10' is preferably elevated above the fixed contact surfaces to a level approximately equal to the plane of aligned faces of the fixed contacts.
The end of each movable contact arm 21 and 23 is reversely bent, at a place approximately midway along its length, toward the floor of the casing into a plane oblique to the face of its fixed contact and then, at a place approximately half way further along its length, bent outwardly and upwardly toward the end walls of the casing, thus providing a straight surface 21c and 23c on each arm of the contact strip over each of the fixed contacts 21 and 23. In the manner described, the movable contact arms are given an S configuration at the end of their arms.
The switch can be made in single pole, double throw form or multipole, double throw form. In the drawing a two-pole form is illustrated in which the casing is divided lengthwise into compartments by a low central partition 10d running from one end to the other of the casing, separating the contacts of one pole from those of the other.
The movable contact 20 is formed with its arms 21, 23 inclined upwardly away from the fixed contact and is thus biased to open circuit position. To move the arms selectively into engagement with their respective fixed contacts, an actuating member 30 molded from insulating material into the form illustrated in FIG. 5 is pivotally mounted in the casing. As viewed in longitudinal section (FIG. 1), it appears as a flattened four-sided parallelogram with its ends truncated and with an upper flattened midsurface 34. For pivotally mounting the actuator in the casing, trunnionlike projections 32 are formed on each side of the actuator and extend from the flattened top 34 of the actuator toward the side walls of the casing. For pivotally supporting the trunnions, recesses 10r are formed in the side walls of the casing with peaked bearing bosses 10b in their bottoms to engage with corresponding notches 32n in the under side of each projection 32. The divergent faces 31, 33 on the sides of the actuator facing the bottom of the casing are adapted to engage the arms 21, 23, respectively, of the movable contact and flex those arms down into engagement with the fixed contacts 14, 16, respectively, as the actuator is tilted about its bearing pivots 10b into one side or the other from the center or neutral position.
As the actuator 30 is tilted, one or the other of its upper or outer faces 35 and 37 which are flat are adapted to engage the under side of the cover to limit the tilting movement of the actuator, for example as shown in dotted lines in FIG. 1. This prevents overstressing the flexible contact arms of the movable contact.
To cause the actuator 30 to tilt in one direction or the other from the neutral or mid position in which it is shown in full lines in FIG. 1, an operating lever 50 is mounted for pivotal movement within a cylindrical hollow neck 42 that is mounted fixedly on a metallic mounting plate 44. The mounting plate has parallel side portions 46 bent at right angles to the plane of the plate 44 to lie against the sidewalls of the casing 10. To secure the plate 44 on the casing and simultaneously to hold the cover 12 on the casing, the extremities 48 of the parallel side arms 46 are bent inwardly under shoulders formed by recesses indented into the bottom corners of the sidewalls of the casing. Neck 42 is convergently narrowed sharply near its mouth to form an internal collar through which the handle portion of the operating lever 50 extends. The operating lever has a large ball-shaped portion 51 midway along its length which forms a bearing surface that is pressed against the interior of the collar. The lever extends internally beyond the ball portion and is axially bored to receive slidably a hollow cylindrical member or plunger 53 which is closed and pointed at its inner end to be pressed against the actuating member 30 by a coiled compression spring 55 that is contained within the plunger 53 and presses at one end against the upper end of the bore and handle and at the other end against the bottom of the plunger.
To receive the end of the plunger 53, the actuating member 30 has formed in its flat top surface 34 a depression, the bottom of which has three short parallel lateral channels or notches 57, 58 and 59 with channel 58 being in the middle of the depression of the actuating member so that when the handle has its axis coincident with the axis of the neck 42 it extends vertically (as illustrated in FIG. 1), the pressure of the plunger is normal to the actuating member 30 and holds it in midposition (horizontally, as shown in full lines in FIG. 1) wherein it is preferably disengaged from both of the movable contact arms 21 and 23, so that both arms are disengaged from their fixed contacts.
The tilting of the operating lever to the left in FIG. 1 causes the plunger 53 to move to the right in the recess of the actuating member 30 until the plunger point enters the channel 59 wherein the parts remain and rest.
If it is desired to make a momentary contact switch in one direction or the other or both, the channels 57 and 59 (one or both) may be omitted. If this is done, it will be necessary to hold the lever in its tilted position in order to maintain engagement between the fixed and movable contacts. As soon as the manual pressure is released from the lever, the pressure of the contact arms, 21 or 23 as the case may be, and together with the inclination of the sides of the recess, acting upon the end of the plunger, will cause the operating lever to return to its intermediate position as illustrated in FIG. 1.
During movement of the operating lever 50 from intermediate into either end position, the end of the actuating member tilts down so that its under surface engages the movable contact 21 or 23 and flexes it down toward the fixed contact 14 or 16. For the purpose of illustration two dotted line positions of the movable contact arm 23 are shown in FIG. 1, showing progression from open circuit to closed circuit position. Initial engagement of movable and fixed contacts is shown in the first dotted position. Thereafter the reversely bent end portion 23c of the movable contact is pressed with increasing pressure against the surface of the fixed contact 16 and concommitantly slides over it as the movable contact moves into the second dotted position. In moving from the first to the second dotted position, the angular relation of the movable contact to the fixed contact changes until the entire length of the end 23c of the movable contact engages the fixed contact. This action causes a wiping action of the movable contact over the fixed contact and keeps the surfaces clean and bright; and the pressure ensures optimum contact engagement and minimum electrical resistance. Wiping action in the reverse direction occurs as the handle is returned to the intermediate position. The contact 23c maintains good pressure at the point of contact until the movable contact disengages the fixed contact 16.
It is desired to have the contacting end portions of each of the movable contacts pivot about the first bend in its movable arm, as the contacting portions 21 c, 23 c, respectively come into engagement with their fixed contacts. To facilitate this function, the movable contacts are cut away preferably centrally at the first reverse bends by punching out metal to create an elongated aperture when first stamping out the contacts. Alternatively, the bend may be weakened by removing metal from the side edges of the contact strip at the bend; but removing metal at the center is preferable because it provides better stability.
To facilitate increased pressure between the fixed and movable contacts at the area of contact engagement, and also to prevent scoring of the stationary contacts in case of lateral tilting of the contacts, the ends 21c, 23c are bifurcated and each bifurcation is curved laterally throughout its length as shown in FIG. 4 so that a round surface is presented to the fixed contact by each bifurcation.
In addition to the three position switch illustrated (with the right and left positions being either momentary or at rest) the invention is useful also in two position forms in which case the notches or channels 57 and 59 would be retained but notch 58 being filled in completely and levelled off, or slightly humped so that as the lever is moved from the right position to the left position or vice versa, it will come to rest only in one or the other.
While a pivoted lever is disclosed as the preferred operating member, a sliding or other operating member could be used.
Many modifications within the scope of the invention will occur to those skilled in the art. Therefore the invention is not limited to the precise form and arrangement of parts as illustrated and described.
In prior tilt-type switches, stamped sheet metal parts were often used for the movable contacts which were rigid and tended to pit and burn and become rough and uneven after long use. Lacking adequate wiping action between the fixed and movable contact faces, the life and performance of the switch was adversely affected. Difficulties also occurred at the midpoint or central terminal support of the movable contact where dirt and burrs could affect the conductivity of the connection even if the fixed and movable contacts remained clean and smooth.
It is an object of this invention to provide a lever operated tilt-type switch mechanism in which the movable contact has a fixed and permanent support that is not affected by dirt, burrs and foreign matter and which also possesses ability of the movable contact to press on and wipe over the fixed contact surface to keep the contacts clean, smooth and bright.
Other objects and advantages of the invention will appear as it is described in connection with the drawings.
According to the present invention, a pivoted lever is mounted for operation manually to cause tilting of an actuating member or rocker within a casing to cause engagement of one set of contacts or another as the actuating member is rocked into one position or another from an intermediate neutral position. The actuating member acts on flexible leaf type movable contact members which are normally self-biased into open-circuit position. The end portion of each movable contact is of S-shape and its extremity wipes over a fixed contact as engagement between them takes place, the extremity being bifurcated and each bifurcation being laterally curved, throughout its length into trough shape for self-adjustment and for optimum contact pressure over the length of the bifurcation.
In the drawing
FIG. 1 is a longitudinal section view through a switch embodying the invention.
FIG. 2 is a plan view looking into the switch casing of FIG. 1 with the cover, operating lever and rocker removed.
FIG. 3 is a plan view of a movable switch contact as used in FIG. 1.
FIG. 4 is an end view of the movable switch contact as used in FIG. 1.
FIG. 5 is a perspective view of the contact actuating member or rocker.
Referring to the drawings, the movable and current carrying parts of the device are mounted and housed in a hollow molded insulation casing 10 of generally rectangular shape with an open top covered by a flat rectangular plate 12 of stamped or molded insulation or the like. In the floor of the casing near opposite ends fixed switch contacts 14 and 16 are mounted. The fixed contacts preferably have circular disclike heads from which a round stem portion 14s and 16s extend down through round holes in the floor of the casing. However, other types of stems may be employed of such form and shape that conductor wires can be connected to them as terminals.
The fixed contacts are each engaged alternately by arms 21 and 23 of a movable switch contact member 20 stamped from highly conductive thin sheet metal as a strip which is of generally widespread V-shape. The movable contact is secured at its center upon a platform 10' on the floor of the casing by a conductive rivet and terminal member 22 passing therethrough and having a shank 22s passing through the platform and floor of the casing 10 midway between the fixed contacts 21 and 23. The platform 10' is preferably elevated above the fixed contact surfaces to a level approximately equal to the plane of aligned faces of the fixed contacts.
The end of each movable contact arm 21 and 23 is reversely bent, at a place approximately midway along its length, toward the floor of the casing into a plane oblique to the face of its fixed contact and then, at a place approximately half way further along its length, bent outwardly and upwardly toward the end walls of the casing, thus providing a straight surface 21c and 23c on each arm of the contact strip over each of the fixed contacts 21 and 23. In the manner described, the movable contact arms are given an S configuration at the end of their arms.
The switch can be made in single pole, double throw form or multipole, double throw form. In the drawing a two-pole form is illustrated in which the casing is divided lengthwise into compartments by a low central partition 10d running from one end to the other of the casing, separating the contacts of one pole from those of the other.
The movable contact 20 is formed with its arms 21, 23 inclined upwardly away from the fixed contact and is thus biased to open circuit position. To move the arms selectively into engagement with their respective fixed contacts, an actuating member 30 molded from insulating material into the form illustrated in FIG. 5 is pivotally mounted in the casing. As viewed in longitudinal section (FIG. 1), it appears as a flattened four-sided parallelogram with its ends truncated and with an upper flattened midsurface 34. For pivotally mounting the actuator in the casing, trunnionlike projections 32 are formed on each side of the actuator and extend from the flattened top 34 of the actuator toward the side walls of the casing. For pivotally supporting the trunnions, recesses 10r are formed in the side walls of the casing with peaked bearing bosses 10b in their bottoms to engage with corresponding notches 32n in the under side of each projection 32. The divergent faces 31, 33 on the sides of the actuator facing the bottom of the casing are adapted to engage the arms 21, 23, respectively, of the movable contact and flex those arms down into engagement with the fixed contacts 14, 16, respectively, as the actuator is tilted about its bearing pivots 10b into one side or the other from the center or neutral position.
As the actuator 30 is tilted, one or the other of its upper or outer faces 35 and 37 which are flat are adapted to engage the under side of the cover to limit the tilting movement of the actuator, for example as shown in dotted lines in FIG. 1. This prevents overstressing the flexible contact arms of the movable contact.
To cause the actuator 30 to tilt in one direction or the other from the neutral or mid position in which it is shown in full lines in FIG. 1, an operating lever 50 is mounted for pivotal movement within a cylindrical hollow neck 42 that is mounted fixedly on a metallic mounting plate 44. The mounting plate has parallel side portions 46 bent at right angles to the plane of the plate 44 to lie against the sidewalls of the casing 10. To secure the plate 44 on the casing and simultaneously to hold the cover 12 on the casing, the extremities 48 of the parallel side arms 46 are bent inwardly under shoulders formed by recesses indented into the bottom corners of the sidewalls of the casing. Neck 42 is convergently narrowed sharply near its mouth to form an internal collar through which the handle portion of the operating lever 50 extends. The operating lever has a large ball-shaped portion 51 midway along its length which forms a bearing surface that is pressed against the interior of the collar. The lever extends internally beyond the ball portion and is axially bored to receive slidably a hollow cylindrical member or plunger 53 which is closed and pointed at its inner end to be pressed against the actuating member 30 by a coiled compression spring 55 that is contained within the plunger 53 and presses at one end against the upper end of the bore and handle and at the other end against the bottom of the plunger.
To receive the end of the plunger 53, the actuating member 30 has formed in its flat top surface 34 a depression, the bottom of which has three short parallel lateral channels or notches 57, 58 and 59 with channel 58 being in the middle of the depression of the actuating member so that when the handle has its axis coincident with the axis of the neck 42 it extends vertically (as illustrated in FIG. 1), the pressure of the plunger is normal to the actuating member 30 and holds it in midposition (horizontally, as shown in full lines in FIG. 1) wherein it is preferably disengaged from both of the movable contact arms 21 and 23, so that both arms are disengaged from their fixed contacts.
The tilting of the operating lever to the left in FIG. 1 causes the plunger 53 to move to the right in the recess of the actuating member 30 until the plunger point enters the channel 59 wherein the parts remain and rest.
If it is desired to make a momentary contact switch in one direction or the other or both, the channels 57 and 59 (one or both) may be omitted. If this is done, it will be necessary to hold the lever in its tilted position in order to maintain engagement between the fixed and movable contacts. As soon as the manual pressure is released from the lever, the pressure of the contact arms, 21 or 23 as the case may be, and together with the inclination of the sides of the recess, acting upon the end of the plunger, will cause the operating lever to return to its intermediate position as illustrated in FIG. 1.
During movement of the operating lever 50 from intermediate into either end position, the end of the actuating member tilts down so that its under surface engages the movable contact 21 or 23 and flexes it down toward the fixed contact 14 or 16. For the purpose of illustration two dotted line positions of the movable contact arm 23 are shown in FIG. 1, showing progression from open circuit to closed circuit position. Initial engagement of movable and fixed contacts is shown in the first dotted position. Thereafter the reversely bent end portion 23c of the movable contact is pressed with increasing pressure against the surface of the fixed contact 16 and concommitantly slides over it as the movable contact moves into the second dotted position. In moving from the first to the second dotted position, the angular relation of the movable contact to the fixed contact changes until the entire length of the end 23c of the movable contact engages the fixed contact. This action causes a wiping action of the movable contact over the fixed contact and keeps the surfaces clean and bright; and the pressure ensures optimum contact engagement and minimum electrical resistance. Wiping action in the reverse direction occurs as the handle is returned to the intermediate position. The contact 23c maintains good pressure at the point of contact until the movable contact disengages the fixed contact 16.
It is desired to have the contacting end portions of each of the movable contacts pivot about the first bend in its movable arm, as the contacting portions 21 c, 23 c, respectively come into engagement with their fixed contacts. To facilitate this function, the movable contacts are cut away preferably centrally at the first reverse bends by punching out metal to create an elongated aperture when first stamping out the contacts. Alternatively, the bend may be weakened by removing metal from the side edges of the contact strip at the bend; but removing metal at the center is preferable because it provides better stability.
To facilitate increased pressure between the fixed and movable contacts at the area of contact engagement, and also to prevent scoring of the stationary contacts in case of lateral tilting of the contacts, the ends 21c, 23c are bifurcated and each bifurcation is curved laterally throughout its length as shown in FIG. 4 so that a round surface is presented to the fixed contact by each bifurcation.
In addition to the three position switch illustrated (with the right and left positions being either momentary or at rest) the invention is useful also in two position forms in which case the notches or channels 57 and 59 would be retained but notch 58 being filled in completely and levelled off, or slightly humped so that as the lever is moved from the right position to the left position or vice versa, it will come to rest only in one or the other.
While a pivoted lever is disclosed as the preferred operating member, a sliding or other operating member could be used.
Many modifications within the scope of the invention will occur to those skilled in the art. Therefore the invention is not limited to the precise form and arrangement of parts as illustrated and described.