US2483831A - Electric switch - Google Patents

Description

D. F. ILLIAN ELECTRIC SWITCH Oct. 4, 1949.

Fngwl Feb. 10, 194e 2 Sheets-Sheet l INVENTOR.

Doug/as F I /lian 'Oct 4, 1949. D. F. ILLIAN 2,483,831

ELECTRIC swITcH Filed Feb. 10, '1948 4 2 Sheets-Sheet 2 IGS THIRD 3-Jfire 9 Source FIG. IO

Patented Oct. 4, 1949 ELECTRIC SWITCH Dough.; F. Iman, chicago, ni., assigner to noipoint Inc., a corporation of New York Application February 10, 1948, Serial No. 7,420

4 claim. 1

The present invention relates to electric switches; and more particularly, to improvements in switches of the character of that disclosed in U. S. Patent No. 2,203,236, granted on June 4, 1940, to Charles P. Randolph et al.

yWhile not limited thereto, the electric switch is especially applicable to the control of electric range heating elements to provide a plurality of heating eiects or degrees of heat. For example, the switch can be used to control the surface hot plates to provide various degrees of heat ranging from comparatively high to relatively low heat intensities; and also to control the heating elements of an oven to provide preheat, bake and broiling heats.

In multi-position electricr switches employed in .'ectric heating systems of the character noted,

ternal structure of the switch in the event that a contact pair stick or welds together.l In the event such afault develops a short-circuit is produced incident to operation of the switch to another circuit controlling position; which shortcircuit is usually severe due to the fact that such systems ordinarily utilize a three-wire source of current supply having a line-to-line -voltage of approximately 236 volts.

Accordingly, it is an object of the present invention to provide an improved electric switch that is so constructed and arranged that the possibility of a short-circuit within the internal structure of the switch is greatly minimized and substantially eliminated.

Another object of the invention is to provide a multi-position electric switch capable of a large number of distinct control positions and incorporating a minimum number of movable contact ngers.

A further object of the invention is to provide a multi-position electric switch of the rotary type of improved and simplified construction and arrangement.

In accordance with one feature of the invention an electric switch of the rotary type is provided that comprises an oif control position and five individual heating control positions, which six distinct control positions are obtained by only four contact fingers incorporated in the switch.

Further features of the invention pertain to the particular arrangement of the elements of the electric switch, whereby the above-outlined and additional operating features thereof are attained.

The invention, both as to its organization and 2 method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specication taken in connection with the accompanying drawings, in which Figure l is a front view of an electric switch embodying the present invention; Fig. 2 is a rear view of the switch shown in Fig. l, with the rear cover removed; Fig. 3 is a sectional view/of the switch taken both in the direction of the arrows along the line 3-3 in Fig. 1 and in the direction of the arrows along the line 3-3 in Fig. 2; Fig. 4 is a sectional view of the switch taken in the direction of the arrows along the line 4--4 in Fig. 3; and Figs. 5 to 10, inclusive, are diagrammatic illustrations of the combination of the switch and a two-section heating unit and a three-Wire source of current supply.

More particularly, Figs. 5 to 10, inclusive, re-

spectively illustrate the corresponding six heating control positions of the switch. 1

Referring now to Figs. 1 to 4, inclusive, 4the electric switch II there illustrated, and embodying'the features of the present invention, comprises a supporting base or panel I2 formed of a suitable electrical insulating material, such as a phenol condensation product. Preferably, the panel I2 is of unitary molded construction and is provided with rearwardly projecting side walls I3 and I4 and rearwardly projecting top and bottom walls I5 and IB defining a shallow'centrally disposed chamber Il in the rear face thereof. The top wall I5 has four longitudinally extending substantially parallel spaced apart shallow grooves I8, I9, 20 and 2| formed therein and p0- sitioned between the side walls I3 and I4. Four longitudinally extending strips or contact ngers 22, 23, 24 and 25 are secured to the panel I2 adjacent the upper ends thereof and projecting over the chamber Il. More particularly, the four contact fingers 22, 23, 24 and 25 are respectively secured to the panel I2 by four hollow eyelets 26, 21, 28 and 29 and are respectively provided with upwardly directed extensions or tails 22a, 23a, 24a and 25a respectively disposed in the grooves I8, I9, 2u. and 2|.

Three integrally threaded hollow sleeves 30, 3l

, and 32, constituting load terminals, are arranged tive load terminals 30, 3| and 32 so that three load fixtures may be directly secured in place in con- Maasai tact with the respective extensions 22a, 23a and 24a by the respective load terminals 33, 3| and 32 utilizing three screws, not shown.

A laterally extending bus 33 is secured to the bottom wall of the chamber I1 by an arrangement including t`wo integral tabs 34 and 35 carried thereby and projecting into corresponding openings formed in the panel |2. The bus 33 is provided with a longitudinally directed extension 33 lying adjacent to the side wall I4; which extension 33, in turn, is provided with a tab 31 overlying the extension 25a and extending into the groove 2|. Finally, a fixture 33 extends through aligned openings formed in the tab 31 and in the extension 25a and is anchored in place in an aligned opening formed in the top wall I3. Accordingly, the bus 33 is directly electrically connected via the extension 33, the tab 31 and the fixture 33 to the extension 25a and consequently 'to the contact linger 25.

Three longitudinally extending line terminals 35, 43 and 4| are secured to the panel I2 adjacent the upper ends thereof and projecting over the chamber I1. More particularly, the three line terminals 33, 43 and 4| are arranged in spacedapart relation between the side walls I3 and I4 and respectively secured to the panel |2 by three hollow eyelets 42, 43 and 44 and are respectively provided with downwardly directed extensions or tails 33a, 43a and 4|a projecting over the bottom wall I3. The extension 4|a projects substantially straight downwardly from the rear face of the panel l2; the extension 33a projects downwardly from the rear face of the panel I2 and is then offset toward the front face thereof; while the extension 43a projects downwardly from the rear face of the panel I2 and is then oiset further toward the rear; whereby the extreme outer ends of the extensions 33a, 43a and 4|a are spread apart in order to accommodate the connection thereof to the respective three line terminals of a three-wire source of current supply.

The four contact fingers 22, 23, 24 and 25 are secured to the panel I2 adjacent to the upper end thereof; and the four extensions 22a, 23a, 24a and 25a are suitably mutually insulated from' each other and from the exterior by three interposed barriers 45, 43 and 41 and by theI upper ends of the side walls I`3 and I4. Similarly, the three line terminals 33, 43 and 4I are secured to the panel I2 adjacent to the lower end thereof; and the three extensions 39a, 43a and 4|a are suitably mutually insulated from each other and from the exterior by two interposed barriers 43 and 49 and by the lower ends of the side walls I3 and I4. Preferably, the barriers 45, 43 and 41 are molded integrally with the top wall l; and the barriers 43 and 49 are molded integrally with the bottom wall I3.

Preferably, the contact fingers 22, y23, 24 and 25 are formed of a resilient spring material, such as a suitable copper alloy; and are biased toward the panel I2 and adjacent to the bottom wall of the chamber I1 due to their inherent resiliency; while the line terminals 33, 43 and 4I are formed v of relatively heavy rigid m'etal stock, such for example, as copper or the like. Also it is preferable that the bus 33 be formed of fairly heavy rigid metal stock, such for example as copper or the like.- The extreme lower ends of the contact iingers 22 and 23 underlie the extreme upper end of the line terminal 39; and the extreme lower ends of the contact fingers 24 and 25 underlie the respective extreme upper ends of the line terminals 43 and 4|. Also the extreme lower ends of the contact . nngers 23, 24 and 25 overlie the bus 33.

As best shown in Figs. 2, 3 and 5 to 10, inclusive. in the switch II, a first stationary contact 3| is carried on the left-hand upper inner end of the ilrst line terminal 33 and cooperates with a first movable contact 3| carried on the lower outer end of the ilrst contact iinger 22; a second stationary contact 32 is carried on the right-hand upper inner end of the first line terminal 33 and cooperates with a second movable contact 32 carried on the lower outer end of the second contact finger 23; a third stationary contact 33 is carried on the left-hand outer face of the bus 33 and cooperates with a third movable contact 33 carried on the lower inner end of the second contact nnger 23; a fourth stationary contact 54 is carried on the upper inner end of the second line terminal 43 and cooperates with a fourth movable contact 34 carried on the lower outer end of the third contact linger 24;- a fifth stationary contact 53 is carried on-ie central outer face of the bus 33 and cooperates with a iifth movable contact 33 carried on the lower inner end of the third contact ilnger 24; and a sixth stationary contact 33 is carried on the upper inner end of the third line terminal 4| and cooperates with a sixth movable contact 33 carried on the lower outer end of the fourth contact linger 23. Preferably, the six stationary contacts 3|' to 53, inclusive, and the six movable contacts 3| to 33, inclusive, are formed of precious metal, such for example, as silver or a suitable alloy thereof and are suitably secured to the responsive line terminals 33, 43 and 4| and to the respective contact lingers 22, 23, 24 and 23, and to the bus 33 in the manner indicated. As previously noted, the four contact ngers 22, 23, 24 and 25 are biased inwardly toward the adiacent bottom wall of the chamber I1 into first positions and are movable outwardly awayJrom the bottom wall of the chamber |1 into second positions. Accordingly, when the four contact fingers 22, 23, 24 and 23 occupy their normal iirst positions, the contacts 5| and 3| are disengaged, the

5 contacts 52 and 32 are disengaged, the contacts 33 and 33 are engaged, the contacts 54 and 34 are disengaged, the contacts 55 and 35 are engaged, and the contacts 53 and 33 Vare disengaged, as clearly illustrated in Fig. 5. On the other hand,

when the four contact fingers 22, 23, 24 and 23 occupy their operated second positions, the contacts 5| and 3| are engaged, the contacts 52 and 62 are engaged, the contacts 53 and 33 are disengaged, the contacts 54 and 34 are engaged, the

55 contacts 55 and 35 are disengaged, and the contacts 53 and 33 are engaged. Of course, when the contact ngers 22, 23, 24 and 25 are released, after they have been operated to their second positions, they are returned to their normal ilrst 50 positions as illustrated in Fig. 5, due to their inherent resiliency.

Also, as illustrated in Figs. 5 to l0, inclusive, the switch is adapted to be employed In an electric control system for use in the heatingl circuit of an electric range. More particularly, the system comprises a two-section heating unit 13, including the sections 1| and 12; which heating unit 13 may comprise one of the surface heating units of the electric range. The two sections 1| and 12 of the heating unit 13 respectively include two outside terminals and a. common intermediate terminal; the common intermediate terminal being connected to the ilrst load terminal 33, the outside terminal of the first section 1| being connected to the second load terminal 3| and the outside terminalof the second section 12 being connected to the third load terminal 32. The sections 1i and 12 may have the same or different heat-producing ratings, but it is preferable, in order to obtain fiexibility in the production of different degrees of heat, that the two sections 1I and 'I2 have different heat-producing ratings. For example, the two sections 1i and 12 may have 'the respective wattage ratings of 840 and 1260, when they are connected directly across a 236 volts A. C. source of current supply.

Also the system comprises a source of current supply of the Edison three-wire type, which may be either A. C. or D. C., although an A. C. source is normally employed. The source of current supply comprises flrst and second main terminals respectively connected to the first and third line terminals 39 and 4i and a neutral terminal connected to the second line terminal 4i). For example, the source of current supply may provide an approximate voltage of 236 volts between the two main terminals and a voltage of approximately 118 volts between either of the main terminals ,and the neutral terminal.

When the switch Il is'operated to its first or' off heat position shown in Fig. 5, the contact fingers 22, 23, 24 and 25 are moved to their first positions; whereby the contact pairs 5I, 6i and 52, 62 and 54,'64 and 56, 66 are disengaged; and the contact pairs 53, 63 and 55, 55 are engaged. Accordingly, the two sections 'li and 12 are shortcircuited in multiple circuit relation, as shown by the broken lines, via the second and third contact fingers 23 and 24'and the bus 33. K

When the switch Ii is operated to its second or high heat position shown in Fig. 6,` the contact fingers 23 and 24 are moved to their first positions and the contact fingers 22 and 25 are moved to their second positions; whereby the contact pairs 5i, 6| and 53, 63 and 5.5, 65 and 5", 56 are engaged; and the contact pairs 52, 62 and 54, 64 are disengaged. Accordingly, the two sections 'il and 12 are connected in multiple, as shown in the heavy lines, across the 236 volts source.

When the switch Il is operated to its third or second heat position shown in Fig. 7, the contact finger 24 is moved to its first position and the contact fingers 22, 23 and 25 are moved to their second positions; whereby the contact pairs 5i, 6| and 52, 62 and 55, 65 and 56, 66 are engaged; and the contact pairs 53, 63 and 54, 64 are disengaged. Accordingly, the section 12 is connected, as shown in heavy lines, across the 236 volts source and the section 1 I is short-circuited via the contact fingers 22 and 23 and the first line terminal 39.

When the switch il is operated to its fourth or third heat position shown in Fig. 8, the contact fingers 22 and 24 are moved to their first positions and the contact fingers 23 and 25 are moved to their second positions; whereby the contact pairs 5I, '6i and 53, 63 and 54, 84 are disengaged; and the contact pairs 52, 62 and 55, 55 and 56, 66 are engaged. Accordingly, the sections 1i and 12 are connected, as shown in heavy lines, in series circuit relation across the 236 volts source. i

When the switch Il is operated to its fifth or low heat position. shown in Fig. 9, the contact fingers 23 and 25 are moved to their first positions and the contact fingers 22 and 24 are moved to their second positions; whereby the contact pairs 5l, 6| and 53,-53 and 54, 64 are engaged; and the contact pairs 52, 62 and 55, B5 and 56, 66 are disengaged. Accordingly, the section 12 is connected, as shown in light lines, across the 118 volts source and the section 1| is as shown in broken lines, open circuited.

Finally, when the switch Il is operated to its sixth or warm heat position shown in Fig. 10, the contact fingers 22 and 25 are moved to their first positions and the contact fingers 23 and 24 are moved to their second positions; whereby the contact pairs 5l, 5l and 53, 63 and 55, 65 and 56, 65 are disengaged; and the c'ontact pairs 52, 62 and 54, 64 are engaged, Accordingly, the sections 1| and 12 are connected, as shown in light lines, in series circuit relation across the 118 volts source.

Now assume that the switch il occupies its ofi heat position shown in Fig. 5 and that it is progressively operated through its high heat position, its second heat position, its third heat position, its low heat position and its warm heat position respectively shown in Figs. 6 to 10, in-

clusive, and then back into its off heat position shown in Fig. 5. When the switch ii is moved from its ofi heat position shown in Fig. 5 to its high heat position shown in Fig. '6, the contact fingers 22 and 25 are moved from their first positions to their second positions; while the contact fingers 23 and 24 remain in their first positions. When the switch Il is moved from its high heat position shown in Fig. 6 to its second heat position shown in Fig. 7, the contact finger 22 is flrst moved from its second position to its first position, the contact finger 23 is then moved from its first position to its second position and then the contact nger 22 is moved from its first position to its second position. When the switch Il is moved from its second heat position shown in Fig. 7 to its third heat position shown in Fig. 8, the contact finger 22 is rst moved from its second position to its first position, then the contact finger 25 is moved from its second position to its first position and then the contact finger 25 is moved from its first position to its second position. When the switch il is moved from its third heat position shown in Fig. 8 to its low heat position shown in Fig. 9, the contact finger 25 is moved from its second position to its first position, then the contact finger 23 is moved from its second position to its first position, then the contact finger 24 is moved from its first position to its second position and then the contact finger 22 is moved from its first position to its second position. When the switch Il is moved from its low position shown in Fig. 9 to its warm position shown in Fig. 10, the contact finger 22 is moved from its second position to its first position and then the contact finger 23 is moved from its first position to its second position. When the switch Ii is moved from its warm heat position shown in Fig. 10 to its off heat position shown in Fig. 5, the contact finger 23 is moved from its second position to its first position and then the contact finger 24 is moved from its second position to its first position.

In view of the foregoing it will be understood that as the switch H is moved from one of its indexed positions to the adjacent indexed position, it is moved through one or more intermediate positions in order positively to insure inassassi 7 terruption of the circuit established in the ons indexed position before completion of the circuit established in the adjacent indexed position. Also from an examination of Figs. to l0, inclusive, it will be observed that by virtue of the arrangement of the six contact pairs 8|; 8| to 58, 86, inclusive, it is impossible to produce a short-circuit upon either the 236 volts source or upon the 118 volts source through the inf; ternal structure of the switch II. This arrangement is very advantageous in view of the fact that in switches of this general character, occasionally a contact pair will stick or weld together. When this fault appears in prior switches of this general type there has always been the possibility of a short-circuit in the internal structure of theswitch as the switch is subsequently operated to another position, re-

sulting in considerable damage to the switch and the general alarm of a person utilizing the electric range. However, in the improved circuit controlling system disclosed above, there is no possibility of a short-circuit even though the fault mentioned develops since the sticking or welding together of any contact pair therein cannot possibily produce a short-circuit within the internal structure of the switch |I as it is operated to the various indexed positions thereof.

For the purpose of operating the switch II to each of its six indexed positions, a mechanism 8| is provided that is of the general character of that disclosed in the previously mentioned Randolph patent. As best shown in Fig. 3, the mechanism 8| is carried by the central portion of the front face of the panel I2 and comprises a rotatable operating shaft 82, the inner end of which is journaled in a bearing 88 formed in the front face of the panel I2 and theouter end of which is provided with a flat surface 82a which is adapted to receive an operating handle or knob, not shown. The operating shaft 82 is secured in place by an arrangement including a front cover 84, formed of metal, that is secured to the front face of the panel I2. More particularly, the front cover 84 is substantially cupshaped including a front wall 85 and a marginal wall 8S carrying two outwardly extending tabs B1. The two tabs 81 are directly secured to the front face of the panel I2 by two hollow eyelets 88; and the front wall 85 is provided with a centrally disposed inwardly extending boss 88 having an opening 98 formed therein through which the outer end of the operating shaft 82 extends. The mid-section of the operating shaft 82 is provided with a spline upon which a nut or fixture 9| of hexagon shape is rigidly secured; the six faces provided on the xture 8| establishing the six indexed positions of the operating shaft 82 and consequently of the switch II as explained more fully hereinafter. The inner end of the boss B9 engages the adjacent face of the fixture 9| in order securely to return the operating shaft 82 in position for rotary movement; whereby the front cover 88 cooperating with the front face of the panel I2 houses the mechanism 8|. Further, two flexible springs 82 formed of steel or the like are arranged within the front cover 84 and positioned on opposite sides of the of the springs 92 carry lugs 92a projecting through cooperating openings 88a formed in the marginal wall 86. More particularly. the springs 92 extend substantially diametrically across the interior of the front cover 88, the intermediate sections thereof engaging the opposite faces of the nxture 8| in order to establish the six indexed positions thereof in an obvious manner.

Finally, the mechanism 8| comprises a disk 88 rigidly secured to the operating shaft 82 against a collar 88 adixed to the operating shaft 82 and disposed intermediate the ilxtln'e 8| and the front face of the panel I2. Accordingly, the disk 98 is rotatable with the operating shaft 82 and is disposed closely adjacent to the front face of the panel I2. Further, four laterally spacedapart and aligned openings III, |82, |88 and |88 are formed through the panel I2 and positioned below the respective four contact fingers 22, 28, 28 and 28. 'I'he four openings |8I, |82, |88 and |88 are arranged between the lower ends of the respective four contact fingers 22, 28, 28 and 28 and the respective eyelets 28, 21, 28 and 28, and carry of the bearing 83; whereby the plungers |81, |88, t

|08 and |05 are disposed 'at four progressively greater radii with respect to the center line of the bearing 88 and the operating shaft 82 as clearly shown in Fig. 4. Accordingly, the inner rounded ends of the four plungers |81, |88, |88 and |85 respectively cooperate with the adjacent surfaces of the four operating ngers 28, 28, 25 and 22; while the outer rounded ends of the four plungers |81, |88, |08 and |08 respectively cooperate with four adjacent arcuate surfaces 88a, 98h, 88o and 88d provided on the disk 88. Specifically, the four arcuate surfaces 98a, 88h, 98e and 88d provided on the disk 88 are concentrically arranged and have progressively increasing radii. The innermost arcuate surface 88a provided on the disk 88 comprises a combination of outwardly extending depressions, one vof which is indicated at 88w, and intervening fiat surfaces cooperating with the outer end of the plunger |81. Likewise, the next outermore arcuate surface 88h provided on the disk 98 comprises a combination of outwardly extending depressions, one of which is indicated at vided on the disk 88 comprises a combination of outwardly extending depressions, one of which is indicated at 88s, and intervening flat surfaces cooperating with the outer end of the plunger |85.

When the operating shaft 82 occupies its first indexed position the depressions 98w, 88x, 9811 and 882 formed in the disk`88 respectively overlie the adjacent outer ends of the four plungers |81, |88, |88 and |08; whereby the four plungers |01, |88. |88 and |05 are respectively slid in the respective openings |88, |82, |88 and |8| toward the front face of the panel |2 into the respective depressions 9810, 88x, 88u and 882 due to the resiliency of the respective four contact fingers 28, 28, 28 and l I 9 Y 22 causing the four contact nngers 24, 23, 23 and 22 to be moved to their first positions as previously explained. Subsequently, as the operatingshaft 82 is rotated from its first indexed position to its second indexed position, it being assumed that the operating shaft 82 is rotated in the clockwise direction as viewed in Fig. 1, the disk 93 is rotated approximately 60 in the counterclockwise direction as viewed in Fig. 4. At this time the outer ends oi' the plungers |08 and |05 are moved out of cooperating relation with respect to the respectively associated depressions 93u and 93a formed in the disk 93 onto the adjacent flat surfaces of the disk 93; whereby the plungers |08 and |05 are slid inwardly in thelrespective openings |04 and formed in the panel I2; whereby the inner ends of the respective plungers |08 and |05 move the respectively associated contact fingers 25 and 22 from their first positions to their second positions. At this time the inner ends of the plungers |01 and |06 still ride in the respective depressions 93w and 93a: formed in the disk 93; whereby the plungers |01 and |06 remain in their original positions retaining the respective contact fingers 24 and 23 in their first positions.

In view of the foregoing description of the mechanism 8|, it will be understood that the combination of depressions 93w, etc., formed in the arcuate surface 93a are angularly spaced apart and are of the required arcuate lengths in order correspondingly to controlthe position of the associated plunger |01 in order selectively to operate the associated contact finger 24. Of course, the combinations of depressions formed in the other arcuate surfaces- 9317, 93e, and 93d of the disk 93 are appropriate in order selectively to control the associated plungers |08, |08 and |05 and consequently the contact fingers 23, 25 and 22. Thus it will be understood that the required circuit combinations in the six indexed positions oi'. the switch are predeterfnined by the combination of depressions formed in the four arcuate surfaces 93a, 93h, 93e and 93d of the disk 93. Further it will be understood that the resiliency of any contact finger 22, etc., is sufficient to return it from its second position back to its first position and to restore the associated plunger |05, etc., in

wall 83 of the front cover 84 has two openings 85a formed therein that are adapted to receive screws carried by an associated supporting panel, not shown; whereby the switch as a whole may be removably secured to the supportingk panel mentioned. Finally, the outer end of the operating shaft 82 projects through an opening formed in the supporting panel, not shown, and carries the operating handle or knob, not shown, previously mentioned. Ultimately, the supporting panel, not shown, may be provided with indicia cooperating with the operating handle or knob, not shown, and indicating the six indexed positions of the operate shaft 82 and the switch and consequently the six indexed heat positions thereof. terminals 30, 3| and 32 are connected to the appropriate terminals of the heating unit 10; and the tails of the line terminals 39, 40 and 4| are appropriately connected to the terminals of `the source of currentsupply; all in the manner previously explained.

While the switch has been described as comprising six indexed positions, it will be readily understood that any one or more of these indexed positions may be eliminated if not required in tthe control of the associated heating circui In view of the foregoing it is apparent that a multi-position electric switch has been provided which is of improved construction and arrangement facilitating ready and convenient control of the heating positions of an associated heating unit and substantially eliminating the hazards of short-circuits.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein, 'and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

the associated depression 93a, etc., formed i`n the disk 93 when the disk 93 is rotated in order again to align the depressions 932, etc., with the inner end of the associated plunger |05, etc., after the disk 93 has been rotated to bring a flat surface thereon into cooperating relation with respect to the outer end of the associated plunger |05, etc.

Finally, the switch comprises a rear cover ||0 formed of insulating material, such for example, as a phenol condensation product and suitably secured to a number of bosses .and ||2 projecting rearwardly from the rear face of the panel |2. Accordingly, the rear cover ||0 cooperates with the rear face of the panel |2 in order to house the four contact fingers 22, 23, 24 and 25, the bus 433 and the inner ends of the line terminals 39, 40 and 4|, as well as the six stationary contacts 5|, etc., and the six movable contacts 6|, etc. Further it is noted that the three line terminals 30, 3| and 32 are arranged exteriorly of the rear cover ||0 adjacent to the top of the panel |2 so that they are readily accessible; while the tails 39a, 80a and 4|a of the line terminals 39, 40 and 4|, respectively, are arranged exteriorly of the rear cover ||0 and adjacent to the bottom of the panel |2 so that they are readily accessible. Finally, the front What is claimed is:

1. A switch comprisingr three load terminals, a bus, three line terminals, four movable contact fingers, a first of said contact fingers being connected to a first of said load terminals and movable ybetween first and second positions respectively disengaging and engaging a first of said line terminals, a second of said contact fingers being connected to a second of said load terminals and movable between a first position respectively disengaging said first line terminal and lengaging said bus and a second position respectively engaging said first line terminal and disengaging said bus, a third of said contact fingersv being connected to a third of said load terminals and movable between a first position respectively disengaging a second of said line terminals and engaging said bus and a second position respectively engaging said second line terminal and disengaging said bus, a fourth of said contact fingers being connected to said bus and movable between first and second positions respectively disengaging and engaging a third of said line terminals, and mechanism for selectively moving in a predetermined order each of said contact fingers between its first and second positions.

2. A switch comprising three load terminals, a bus, three line terminals, four resilient contact fingers, a first of said ontact fingers being connected to a first of said oad terminals and mounted for pivotal movement between normal and operated positions respectively disengaging and engaging a first of said line terminals, a. second Of course, the three load` l l of said contact fingers being connected to a second of said load terminals and mounted for pivotal movement between a normal position respectively disengaging said first line terminal and engaging said bus and an operated position respectively engaging said first line terminal and disengaging said bus, a third of said contact iingers being connected to a thirdl of said load terminals and mounted for pivotal movement between a normal position respectively disengaging a second of said line terminals and engaging said bus and an operated position respectively engaging said second line terminal and disengaging said bus, a fourth of said contact fingers being connected to said bus and mounted for pivotal movement between normal and operated positions respectively disengaging and engaging a third of said line terminals, each of said contact ngers being biased into its normal position by its inherent resiliency, and mechanism for selectively moving in a predetermined order each of said contact fingers from its normal position into its operated position and for selectively releasing in a predetermined order each of said contact fingers for return movement from its operated position back into its normal position.

3. A switch comprising three load terminals, a bus, three line terminals, four movable contact fingers, a first of said contact fingers being connected to a first of said load terminals and movable between first and second positions respectively disengaging and engaging a first of said line terminals, a second of said contact fingers being connected to a second of said load terminals and movable between a first position respectively 35 disengaging said first line terminal and engaging said bus and a second position respectively engaging said first line terminal and disengaging said bus, a third of said contact fingers being connected to a third of said load terminals and movable between a first position respectively disengaging a second of said line terminals and engaging said bus and a second position respectively engaging said second line terminal and disengaging said bus, a fourth of said contact fingers being connected to said bus and movable between first and second positions respectively disengaging and engaging a third of said line terminals, and a six-position mechanism for selectively moving said contact fingers between their first and second positions, said mechanism being operative into a first of its positions to move each of said contact fingers into its first position, said mechanism being operative into a second of its positions to move said first and fourth contact fingers into their second positions and to move said second and third contact ngers into their first positions, said mechanism being operative into a third of its positions to move said first and second and fourth contact fingers into their second positions and to move said third contact nnger into its first position, said mechanism being operative into a fourth of its positions to move said rst and third contact fingers into their first positions and to move said second and fourth contact fingers into their second positions, said mechanismr being operative into a, fifth of its positions to move said first and third contact fingers into their second positions and to move said second and fourth contact fingers into their first positions, said mechanism being operative into a sixth of its positions to move said first and fourth contact fingers into their first positions and to move said second and third contact fingers into their second positions.

4. A switch comprising three load terminals, a bus, three line terminals, four movable contact fingers, a. first of said contact fingers being connected to a first of said load terminals and movable between first and second positions respectively disengaging and engaging a first of said line terminals, a second of said contact fingers being connected to a second of said load terminals and movable between a nrst position respectively disengaging said first line terminal and engaging said bus and a second position respectively engaging said first line terminal and disengaging said bus, a third of said contact fingers being connected to a third of said load terminals and movable between a first position respectively disengaging a second of said line terminals and engaging said bus and a second position respectively engaging said second line terminal and disengaging said bus, a fourth of said contact fingers being connected to said bus and movable between rst and second positions respectively disengaging and engaging a third of said line terminals, mechanism including a single rotary operating cam for selectively moving in a predetermined ordereach of said contact fingers between its first and second positions, and means including an insulating panel for supporting each of said elements named.

DOUGLAS F. ILLIAN.

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

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