Switch Construction

This invention relates generally to electrical switches having bases of an insulating material and with two or more fixed electrical contacts in the lower wall thereof. A movable contact element bridges selected ones of these fixed contacts, being movable through the actuator also of insulating material. The present invention deals more particularly with a unique configuration and location for the actuator and an associated spring whereby actuator motion causes the required pivoted and translational movement of the movable contact element across the fixed contacts without necessity for relatively reciprocable intermediate parts or components.

In other switch configurations the actuator has an internal lamp which may have its two leads connected to any combination of two of the following: the spring associated with the actuator, a second spring associated with a fixed switch contact, and a spring associated with a resistor element so arranged in its own recess in the switch case that the one end of this resistor can be electrically connected directly to a fixed contact of the switch. The spring associated with the actuator always contacts the movable contact element.

The general purpose of the present invention is to provide a unique switch construction having a minimum number of component parts, which switch construction also permits a lamp to be incorporated in the movable actuator portion of the switch and to be energized either through a spring associated with the actuator, or through a spring held in the base such that it may be associated with a resistor element connected directly to a fixed contact of the switch. This resistor preferably comprises a simple wire wound type with metal end caps and does not include lead wires and/or a plastic covering etc. Therefor, the resistor element is smaller than these plastic covered types and better suited to use in the unique switch construction disclosed herein.

These unique features can be provided in a switch base of double pole configuration to further expand the illumination possibilities for the externally visible portion of the actuator. The use of relatively inexpensive light weight springs to connect one or more of the lamp leads to a fixed terminal in the base eliminates soldering and the like. In addition, the lamp or bulb is free to move with the movable actuator in such a way that one or more such springs serve as lost motion conductive elements to minimize the degree of flexing and bending of lamp lead wires characteristic of prior art switch constructions.

FIG. 1 is a vertical sectional view through a switch constructed in accordance with the present invention, and illustrates the actuator in one and an alternative position, the latter being indicated in broken lines.

FIG. 2 is a sectional view taken generally on the line 2--2 of FIG. 1.

FIG. 3 is a sectional view taken generally on the line 3--3 of FIG. 1.

FIG. 4 is a vertical sectional view through a switch constructed in accordance with an alternative form of the present invention.

FIG. 5 is a sectional view of still another version for a switch incorporating the present invention.

FIG. 6 is a view of the FIG. 5 switch with the actuator in an alternative position.

FIG. 7 is a plan view of the switch case illustrated in FIG. 6, but with the actuator and movable contact element eliminated.

FIG. 8 is a plan view of the actuator omitted from FIG. 7 above.

FIG. 9 is a sectional view taken generally on the line 9--9 of FIG. 5.

FIG. 10 is a vertical sectional view through a switch constructed in accordance with an alternative embodiment of the invention, with portions broken away to better show certain features of this embodiment.

FIG. 11 is a view similar to FIG. 10 but shows the switch actuator in an alternative position.

FIG. 12 is a vertical sectional view through a three position switch similar to the two position switch of FIGS. 10 and 11.

FIG. 13 is a view similar to FIG. 12 but shows the switch actuator in an intermediate second position.

FIG. 14 is a view similar to FIGS. 12 and 13 but shows the switch actuator in a third position.

FIG. 15 is a sectional view taken along the line 15--15 of FIG. 13.

FIG. 16 is a plan view of the movable contact element shown in FIG. 15 in assembled relationship with other switch components.

FIG. 17 is a perspective view of the FIG. 16 element.

FIG. 18 is a sectional view taken on the line 18--18 of FIG. 15.

FIG. 19 is a sectional view taken on the line 19--19 of FIG. 13.

FIG. 20 is a sectional view through a double pole switch similar in all significant respects to the single pole switch of FIGS. 10 and 11.

Turning now to the drawings in greater detail, FIGS. 1-3 inclusively show a preferred embodiment for the switch wherein the switch base comprises a one piece molded plastic part 10 having an upwardly open cavity 10a, which cavity is defined in part by a bottom wall 10b. The bottom wall is provided with at least two fixed contacts, and as shown three such contacts are provided, one centrally of the generally rectangular switch base as indicated generally at 14 in FIGS. 1 and 3, and two identical fixed contacts 12 and 16 provided on either side of the center contact 14. As best shown in FIG. 3, the upwardly open switch cavity 10a is divided into identical subcavities by a web-like wall portion 10c, and in the preferred embodiment shown the switch is of the double pole-double throw variety wherein two sets of three contacts are provided in the switch cavity 10a and more particularly in each of the subcavities defined by the median wall 10c. FIG. 3 indicates the location for the center fixed contacts 14 and 14a in this double pole-double throw switch arrangement and it will be apparent that fixed contacts 12a and 16a, best shown in FIG. 2, are provided to either side of this central fixed contact 14a in the same manner as referred to previously with reference to the contacts 12 and 16 of FIG. 1.

A movable contact element is slidably received in each switch subcavity, as best shown in FIG. 2, and this movable contact element 18 is adapted to slide across the upper ends of the fixed contacts so as to selectively bridge certain of said fixed contact. As shown in FIG. 1 for example element 18 bridges the center contact 14 and the right hand fixed contact 16. In the alternative position shown in broken lines movable contact element 18 bridges the center fixed contact 14 and electrically connects this contact 14 to the other fixed contact 12.

As best shown in FIG. 3 switch actuator means 20 is movably supported in the switch case 10, and more particularly in the side wall defining means of the case as indicated generally at 22 and 24 in FIG. 3. As shown at 22 and 24 laterally aligned actuator support regions are defined in the side walls of the switch base in order to movably support the actuator 20 for movement between the alternative positions depicted in FIG. 1. The actuator 20 is provided with laterally outwardly projecting portions 20a and 20b which portions are received in laterally aligned openings 10d and 10e so that the actuator 20 is pivotally supported for movement between the positions shown in FIG. 1.

The switch base cavity 10a has appropriately located flats 10f and 10g defined in the locations shown in FIG. 1 for abutting the end portions of pivotally mounted actuator 20 in order to determine the limit positions for the actuator 20. Actuator 20 has a portion accessible from outside the switch case in order to permit movement of this member between the positions shown. As indicated in the drawings the actuator 20 is of the rocker type, but it will be apparent that other configurations for the external portion of the actuator might be substituted for the rocker configuration shown. For example, a paddle or toggle might be formed in the external portion of the actuator 20 without departing from the scope of the present invention.

An important feature of the actuator 20 resides in the fact that it has a depending portion 20 which is received in a recess defined for this purpose in the movable contact element 18 in order to assure the desired movement of the element 18 in response to the above described motion for the actuator 20. As best shown in FIG. 3 the actuator 20 has two such depending portions 20c and 20d, each of which portions is adapted to achieve the desired movement of one of the two contact elements 18, 18 in each of the subcavities defined within the switch case 10.

In further accordance with the present invention spring means 26 is provided on each of the depending actuator portions 20c and 20d and serves to bias each of the movable contact elements downwardly into engagement with the fixed contacts described above. The depending portions, and more particularly the lowermost end portions of these actuator portions are received in recesses 18a in each of the movable contact elements 18, and the lower end of each of the springs 26 engages upturned arcuately shaped portions 18b of the element 18 in order to yieldably urge element 18 downwardly while depending portion 20c of the actuator is moved arcuately about its associated pivot axis as defined by the support regions 22 and 24 described previously.

The center fixed contacts 14 and 14a are provided with relieved areas 15 which permit the lowermost end of the depending portions 20c and 20d to pass through these generally planar upstanding contacts 14 and 14a. The recesses or openings 18a in each of the movable contact elements 18 receive the depending portions 20c and 20d of the actuator 20 only quite loosely in order to permit rocking motion of each contact element 18 as it moves over the upstanding portion of fixed center contact 14. FIG. 2 shows to best advantage the degree of rocking motion possible with the contact element 18 and its associated depending actuator portion 20c and 20d. Although the spring means 26 does comprise a metal coil compression spring acting directly on the movable contact element 18, and therefor must of necessity be at the same electrical potential as element 18, spring 26 is electrically isolated from any other conductive parts as a result of its upper end being in engagement with a downwardly facing surface of actuator 20, said actuator being fabricated from insulating plastic material and being the only element of the switch in contact with the spring 26 other than the movable element 18 itself.

FIG. 4 shows an alternative switch construction incorporating many of the advantages from the switch construction of FIG. 1, and having a modified switch base configuration 110 with two fixed contacts or terminals 114 and 116 provided in the cavity 110a and a third terminal 112 in an elongated cavity 100 to be described. A movable contact element 118 provides selective electrical connection for the fixed contacts 114 and 116 under the action of spring 126 on the arcuate upper side of contact element 118 in much the same manner as described above with reference to the element 18 and surface 18b. The opening 118a of movable contact element 18 is adapted to loosely receive the depending portion 120c of an actuator means 120, which depending portion is generally similar to the depending portion 20c described above with reference to actuator 20 of FIGS. 1-3. A shelf 106 supports one end of contact element 118 in one of two switch positions to be described with reference to FIGS. 5 and 6.

Actuator means 120 includes a hollow interior portion adapted to house an indicator lamp 130, which may be an LED (light emitting diode). The LED 130 has two electrical leads 132 and 134, one of which leads is electrically connected to the upper end of the coiled compression spring 126 such that an electrical path is provided from the LED 130 to the movable contact 118. The other lead 132 associated with the LED or lamp 130 is preferably connected to the third terminal 112 through a spring 133 located in the elongated cavity 100. In a double pole switch such as shown in FIG. 2 for example this LED lead 132 might instead be connected to one of the terminals associated with the other pole (not shown) of the switch base 110. The terminal 112 associated with this lead 132 will generally be electrically connected to ground, and terminal 116 to an appropriate DC voltage for operating the LED. The circuit to be controlled by the FIG. 4 switch is then connected to central terminal 114.

The hollow rocker 120 is of integral one-piece plastic construction except for the provision of a transparent lens 136 provided in its upper end, and serving to provide a window for the illumination from the LED 130.

Turning next to a detailed description of the switch illustrated in FIGS. 5-9 inclusively the switch base 210 is generally similar to that described above with reference to FIG. 4 that is, instead of having a generally symmetrical cavity such as shown in FIGS. 1-3 the movable contact 218 provided in internal cavity 210a of the switch illustrated in FIG. 5 has only two of its three terminals 214 and 216 projecting upwardly into this cavity 210a. The third terminal 212 has its upper end located at the bottom of an elongated cavity 200 housing a resistor 202 and a light coil spring 204 for a purpose to be described.

In order to provide at least two alternative positions for movable contact element 218 of the FIG. 5 switch (and of element 118 in the FIG. 4 switch), the bottom wall of the switch case cavity 210a (110a in FIG. 4) defines generally upwardly facing abutments 206 (106 in FIG. 4) against which the left hand edge of the movable contact element 218 (118 in FIG. 4) is adapted to rest when the switch is moved from the position shown for it in FIG. 5 to that shown in FIG. 6. The action of depending portion 220c of the rocker actuator 220 serves to support a coil compression spring 226 generally similar to the spring 26 described above with reference to FIGS. 1-3 inclusively. That is, the lower end of the spring 226 engages the upper surface 218b of movable contact element 218, and the upper end of spring 226 engages an abutment surface on the underside of the actuator 220, which actuator is formed of one-piece plastic construction, but is hollow so as to receive a lamp 230, and which actuator is fitted with a transparent plastic window 236. Furthermore, the upper end of the spring 226 engages a lead 234 associated with the lamp 230 in order to provide one leg of an electrical circuit for the lamp 230 when the switch is in at least one of its discrete positions.

The other lead 232 for lamp 230 held in the actuator 220 passes through a small opening 220d so as to be entrapped between the upper end of the light resistor connected spring 204, and the inner surface of a spring receiving recess defined for this purpose in the underside of the left hand end of the actuator 220. As best shown by way of comparison between FIGS. 5 and 6, expansion of the spring 204 will cause this lead 232 to remain in contact with the spring 204, and hence with the end of resistor 202 as the switch is moved between the positions shown for it in FIGS. 5 and 6. It will be apparent that the above described cooperation between the upper end of spring 204 and lead 232 is identical to that for spring 133 in FIG. 4 and LED lead 132 in FIG. 4. It will also be apparent that the presence of resistor 202 in the FIG. 5 switch permits 110 volt AC to be applied to terminal 216, and that lamp 230 will illuminate with the switch in this FIG. 5 position, and will not be illuminated in the FIG. 6 switch position. As in the FIG. 4 switch described above, terminal 212 will be connected to ground and center terminal 214 to the circuit to be controlled.

FIG. 7 shows in plan view the switch base 210 with its upwardly open cavity 210a defining the side-by-side subcavities for each of the poles associated with this particular switch embodiment. One side of the switch cavity 210a defines the two contacts 214 and 216 illustrated in FIGS. 5 and 6, and also defines the elongated cavity 200 housing the resistor 202 and its associated light coil spring 204. It will be apparent that both sides of this switch might be identical, that is, with two resistors at each of the two terminals such as that described above with reference to the terminal 212. It will also be apparent that a second such resistor might instead be provided in an elongated cavity to replace the terminal 216a of FIG. 7. Other alternative switch configurations can be constructed given the unique concept of providing the uncoated resistor element (without lead wires) in a small cavity so that one metal end is in direct contact with a terminal and so that the opposite end of this very inexpensive resistor can be connected (without solder) to a lead wire of any conventional type lamp or LED. The light spring 204 serves not only as a convenient means for achieving such a solderless connection, but also serves the function of flexing to accommodate the switch actuator movement, a function formerly accomplished by the lamp's lead wire itself. This continuous flexing of the lamp lead wire can cause failure of the wire long before deterioration of other more rugged switch components.

FIG. 8 shows the rocker 220 with its projecting pivot defining means 220a and 220b which fit into aligned openings 210 in the side wall of the switch base 210. The transparent panel 236 covers the upper end of the hollow actuator 220. Finally, FIG. 9 shows the actuator 230 in vertical section, illustrating the upwardly open hollow configuration such that a cavity 221 is defined for receiving the lamp 230. The depending portion 220c of the one-piece plastic actuator 220 are fitted with springs 226, and one spring engages the movable contact element 218 described above with reference to FIGS. 5 and 6, whereas the other depending portion engages a more conventional movable contact element such as described hereinabove with reference to FIGS. 1-3 (see element 18 of these views).

Turning next to the drawings depicting the switch configuration of FIGS. 10-19 inclusively, these further alternative embodiments incorporate the same invention disclosed above with reference to FIGS. 1-9 inclusively, and these further views also illustrate that the present invention can be utilized in a toggle switch of the type disclosed in prior art U.S. Pat. No. 3,158,704 and others, and that the present invention is not limited to the environment of a rocker type switch such as that shown and described with reference to prior art U.S. Pat. No. 3,711,663. It will be apparent to those skilled in the art that the present invention can also be adapted to other style switches, including but not limited to slide switches and the like.

Turning next to a detailed description of the alternative embodiment illustrated in FIGS. 10 and 11, this particular toggle switch has two positions as illustrated in these two views, and the toggle actuator 320 may comprise a one-piece plastic part as shown, or alternatively, may comprise an upper handle portion which is metal and which is connected at its lower end to a plastic member having the same geometry as the lower integral portion 320b illustrated in FIGS. 10 and 11. In the particular embodiment shown the one-piece plastic actuator 320 has a swaged metal partispherical ball 320a attached to an intermediate portion of the plastic shank 320c. This shank portion includes a reduced diameter portion 320d which may be sonically welded to the lower portion 320b in order to provide for assembly of these metal ball defining portions 320a. Alternatively the partispherical portion 320a may itself be formed of plastic material and in accordance with conventional practice this partispherical portion permits the toggle actuator 320 to move pivotally in the switch case between the position shown for it in FIGS. 10 and 11.

The switch case has been shown only to the extent necessary to disclose the present invention, and includes an upper cover portion 322 defining an upstanding boss 322a which may be threaded to receive suitable retaining nuts or the like in accordance with conventional switch technology. The inner portion of this boss 322a defines a surface for receiving the actuator toggle 320 in order that spring pressure can be applied upwardly to the toggle actuator 320 and thereby maintain the partispherical ball portion 320a in contact with the surface 322b for allowing the pivotal movement of the toggle actuator 320 as described.

The switch case further includes a base portion 310 which may be suitably connected to the cover portion 322 by conventional means, and this base 310 defines an upwardly open cavity shown in part in FIGS. 10 and 11 similar to that for the cavity 10a referred to previously with reference to the FIG. 1 switch configuration. Further, the lower bottom wall of this switch base 310 has provision for mounting two or more fixed contact strips two of which is shown at 312 and 314 in FIGS. 10 and 11. The third fixed contact is omitted from FIG. 10 switch in order to provide a switch position wherein the center terminal or contact 314 is electrically isolated, and the switch is thereby provided with a positive off position. More particularly, movable contact element 318 can be seen in FIG. 11 to have a left hand portion in contact with the upper end of fixed contact 314, but it will be apparent that the right hand end portion of the movable contact 318 engages only the upstanding plastic base 310 more particularly the upwardly projecting portion 310a provided adjacent the slot 310b which may be used for receiving a fixed contact (not shown). In the switch configuration shown in FIGS. 10 and 11 therefor movable contact element provides a switch off condition in the FIG. 11 position, and in the FIG. 10 position a switch on condition.

With particular reference to FIG. 10, the plastic actuator or toggle 320 can be seen to include a depending portion 320e defined by a generally annular slot 320f which slot is adapted to receive a spring 326, which spring serves the same function as that described herein above with reference to the previous embodiments by reference to numeral 26. More particularly the upper end of the spring 326 engages the actuator 320 to urge the actuator upwardly in the switch case in order to maintain the desired position of the toggle during movement of the switch between the two positions shown. The lower end of the spring 326 engages a convexly contoured pair of surfaces 318b similar to the surfaces described above with reference to the movable contact element 18. The spring 326 is therefore electrically connected to the movable contact element 318 and functions in the much the same manner as the spring 26 referred to previously. As the actuator 320 is moved from the FIG. 10 toward the FIG. 11 position the movable contact element 318 not only translates from left to right as a result of the slot 318a provided in the element 318 but said movable element 318 also pivots relative to the upper end of the fixed contact 314 providing a positive action for the element 318.

In summary the actuator 320 differs from the actuator 20 described above with reference to FIG. 1 for example in that the pivotal mounting is different but conventional. On the other hand, the lower end of the actuator 320 differs slightly from that shown in FIG. 1 by virtue of the spring 326 in the FIG. 10 switch having a receptacle for locating this spring in a somewhat more positive manner than that depicted in the previous embodiments of FIGS. 1-9 inclusively. It will be apparent to those skilled in the art that either configuration for the lower end of the actuator 320 or 20 can be varied within the scope of the present invention and it is noted that with the configuration illustrated in FIGS. 10 and 11 the lower portion 320b of the actuator 320 provides a convenient means for defining end abutment surfaces suitable for engaging the side walls of the switch case in order to permit rotation of the actuator 320 about the axis of its upper end or toggle portion. Since the rocker switch of FIGS. 1-9 inclusively does not provide for the same sort of spherical pivot, but rather as definitely defined projections for determining a single pivot axis, this particular design feature of providing for the engagement between the end walls of the lower portion of the actuator such as described above with reference to 320b need not be incorporated in the rocker switches of FIGS. 1-9 inclusively.

It should also be noted that the single pole switch depicted in FIGS. 10 and 11 and the invention incorporated therein, can also be adapted for use in a double pole switch configuration of the type described above with reference to FIGS. 2 and 3. In a double pole switch of this type the toggle style actuator or FIG. 10 would very likely be made with the handle portion being designed for assembly with the lower portion defining the annular slots for the two springs required. Whereas in FIG. 10 the axis of the toggle portion of the actuator 320 is in line with the axis of the depending portion 320e, it will be apparent that in a two pole switch configuration such would not be the case, and as suggested in FIG. 20 the upstanding toggle portion of the actuator 321 would have its axis located intermediate the respective axes of the twin side-by-side depending actuator portions 321e, 321e. FIG. 20 shows how the side portions 321b of this double pole actuator 321 engage the side walls of the switch base 311 in order to restrict pivotal movement of the actuator toggle to a single plane, rather than to permit unrestricted freedom of movement pivotally in its spherical or partispherical bearing as described above.

Turning next to the toggle switch configuration illustrated in FIGS. 12-19, a toggle shaped actuator element is pivotally supported in an upper boss defining portion 422a of the switch cover 422 and these components of the three position switch illustrated in FIGS. 12-19 inclusively are or may be identical to the actuator 320, the cover 322, and the boss portion 322a of the switch illustrated in FIGS. 10 and 11. More particularly, the upper portion (not shown) of the toggle actuator 420 is pivotally supported for movement in at least one vertical plane, and has a lower portion 420b generally similar to that described above with reference to numeral 320b in FIGS. 10 and 11. That is, a downwardly open annular recess 420f houses a spring 426 and a depending portion 420e of the actuator 420 extends through this coil spring so as to engage the opposite edges of an opening 418a in a movable contact element 418, the lower portion 420b of the toggle actuator 420 may either be of the single pole variety described above with reference to FIGS. 10 and 11, or may comprise a double pole configuration such as that suggested in FIG. 20 referred to previously.

Although the actuator 420 is generally similar to that described above with reference to FIGS. 10 and 11 or FIG. 20, the movable contact element 418 is of different configuration being adapted for use in conjunction with the unique arrangement for the fixed contact elements in the lower wall of the switch case or base 410. This element is illustrated in some detail in FIG. 17, but prior to describing the element 418 in detail by reference to FIG. 17 it should be perhaps noted that the switch condition or position shown in FIG. 12 is generally similar to that described above with reference to the two position toggle switch of FIGS. 10 and 11 in that movable element 14 bridges fixed contacts 412 and 414 in this condition. Referring by way of reference to FIG. 14, the movable contact element 418 is there shown in an opposite position generally similar to that described above with reference to FIG. 11 for the two position switch, and wherein the movable contact element 418 bridges the fixed contacts 414 and 416.

FIG. 13 illustrates the toggle actuator 420 in an intermediate "center-off" position wherein the movable contact element 418 is held by the spring 426 in a position isolated from each of the endmost fixed terminals 412 and 416. As in the FIG. 10 switch center fixed terminal 414 has a relieved center portion 415 similar to that shown in FIG. 20 by reference to numerals 315, 315. This clearance opening provides for motion of the depending portion 420e of the actuator 420 as the movable element 418 is moved from the FIG. 12 to the FIG. 14 position, and as said element 418 is held in the FIG. 13 position. With particular reference to FIG. 16, it will be apparent that the lower end of the coil spring 426 engages laterally spaced contact points on the raised convex surfaces as indicated at 418c in this view. FIGS. 16 and 17 show the general configuration for the movable contact element 418 to best advantage. With particular reference to FIG. 17 it will be apparent that the lower end of the spring 426 continually engages this convex surface, the actual point of contact shifting as the movable element itself is shifted between the positions shown for it in FIGS. 12 and 14. Still with reference to the FIG. 13 position (generally designated "center-off") it will be apparent from FIG. 13 that the underside of the movable element 418 has an intermediate flat portion or more correctly longitudinally spaced flat surfaces separated by a recess 418b. Actually two such laterally spaced recesses 418b, 418b are provided as best shown in FIG. 17 on either side of the opening 418a in the element 418, and the fixed contact 414 has uppermost end portions corresponding to the portions 313, 313 of the center contact 314 in FIG. 20 for the FIG. 10 switch. Thus, movable contact element 418 does engage this center contact 414 in the "center-off" position.

It is an important feature of the present invention that the aligned flats 418d on either side of the downwardly open recess 418b do engage the plastic bottom wall of the switch case or base 410. This engagement provides stability for the movable contact element 418 as it rests in its "center-off" position illustrated in FIG. 13. That is, the downward spring pressure exerted centrally of the movable contact element 418 at the points 418c, 418c, referred to previously is reacted by upward pressure from one or both of the upwardly facing surfaces 410b, 410b best shown in FIGS. 12 and 14. Thus, the plastic base 410 is molded with a suitable configuration for achieving this stable position of the movable contact element 418 without necessity for complicated conductive center yoke terminals to achieve this purpose as is true of many prior art switch arrangements of this three position type. The reader is referred to prior U.S. Pat. No. 3,158,704 and No. 3,711,663 for examples of the typical prior art geometry for achieving the "center-off" position with a movable contact element of the general type described herein. It is further noted that the element 418 described above is itself unique in that the flats 418f, 418f are adapted to be supported by the shelf-like portions 410b, 410b of the plastic base to define a stable "center-off" position for toggle actuator 420. In this position the upper ends of contact 414 engage movable element 418 at laterally spaced locations 418b, 418b and spring 426 engages spaced points 418c, 418c. The latter points of spring contact shift as the actuator is moved to the FIG. 12 or FIG. 14 positions, but it is important to note that the convex contour of the surfaces defining these points of spring contact always assures that the element 418 is urged downwardly toward the fixed contact by spring 426 as it is shifted between the positions shown in FIGS. 12, 13 and 14 by depending portion 420e of actuator 420.