Patent Publication Number: US-7211756-B2

Title: Four function electrical rocker switch

Description:
This application is a continuation of application Ser. No. 10/047,246, filed Jan. 14, 2002, now U.S. Pat. No. 6,903,292; which is a continuation-in-part of application Ser. No. 09/235,785 filed Jan. 22, 1999 (as a Continued Prosecution Application of application Ser. No. 09/235,785 filed Jan. 22, 1999), now U.S. Pat. No. 6,339,201; which is a continuation-in-part of application Ser. No. 08/865,921 filed May 30, 1997, now abandoned. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention deals with electrical switches, and more particularly, with multiple function electrical switches that can be placed in a single, standard gang box. 
   2. Description of the Prior Art 
   As the use of electrical equipment in the home and commercial establishments increases, there is a need to increase the number of electrical switches used for controlling or supplying electrical power to such equipment. However, much of this equipment is placed in existing structures where it is difficult to increase the number of gang boxes in which such switches can be placed or increase the number of electrical cables extending through existing walls. To provide adequate heat dissipation and to insure that all equipment is properly connected to a neutral return conductor, the number of switch devices or receptacles in each box is limited and each cable that provides electrical power to such switches and receptacles must also contain the neutral return conductor. 
   At present, triple rocker switches are available, each providing a single pole, single throw on-off switch and requiring two conductors for each switch unit. Thus, there are six conductors crowded into a single gang box which increases the possibility of physical contact between individual conductors or between the conductors and the gang box which may result in short-circuits. Also, the heat produced by these closely placed conductors may exceed safe levels. 
   One approach that reduces the crowding in the gang box and reduces the number of conductors for the switches is shown in U.S. Pat. No. 5,384,441 issued Jan. 24, 1995 and assigned to the assignee of the instant invention and by this reference incorporated into the instant application, makes use of a common phase conductor for each of the three rocker switches. Thus, the number of electrical conductors used in a gang box including such a switch arrangement is reduced to four. The number of rocker switch units, however, remains at three. 
   SUMMARY OF THE INVENTION 
   The instant invention overcomes one of the problems presented by the prior art by permitting the substitution of a single pole, double throw, center-off switch for one of the single pole, single throw on and off switches. The use of a common phase line for the two single pole, single throw switches permits these two switches to be wired using the three conductors of common three conductor cable and insures that the neutral return conductor is present in the cable to which the switches are wired. 
   The single pole, double throw, center-off switch can also be wired to the same three conductors used for the two single-pole, single throw switches. Thus, using the same three conductor cable, the number of switches has been increased to four. It is an object of this invention to provide a novel four function electrical rocker switch. 
   It is an object of this invention to provide a novel four function electrical rocker switch which can be placed within a single gang box. 
   It is an object of this invention to provide a novel four function electrical rocker switch which can be placed within a single gang box and wired to a single three conductor cable. 
   It is still another object of this invention to provide a novel four function electrical switch having two on/off single pole, single throw switches and a single pole, double throw, center-off switch. 
   Other objects and features of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principles of the invention, and the best mode which is presently contemplated for carrying them out. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings in which similar elements are given similar reference characters: 
       FIG. 1  is a front perspective view of a four function electrical rocker switch constructed in accordance with the concepts of the invention. 
       FIG. 2  is a side elevational view of the switch of  FIG. 1 . 
       FIG. 3  is a perspective view of the mounting strap of the switch of  FIG. 1 . 
       FIG. 4  is a bottom plan view of the switch of  FIG. 1 . 
       FIG. 5  is a top plan view of the inside of the base housing of the switch of  FIG. 1 . 
       FIG. 6  is a rear elevational view, partially in section, taken along the line  6 — 6  of  FIG. 5 . 
       FIG. 7  is a fragmentary, side elevational view, partially in section, taken along the line  7 — 7  in  FIG. 5 . 
       FIG. 8  is a top plan view of the movable contact member of the switch of  FIG. 1 . 
       FIG. 9  is a side view of the movable contact member of  FIG. 8 . 
       FIG. 10  is a side elevational view of the movable contact member of  FIG. 9  taken along the line  10 — 10 . 
       FIG. 11  is a top plan view of a fixed contact member of the switch of  FIG. 1 . 
       FIG. 12  is a side elevational view of the fixed contact member of  FIG. 11 . 
       FIG. 13  is a bottom plan view of the cover of the switch of  FIG. 1 . 
       FIG. 14  is a side elevational view of the rocker of the single pole, single throw switch sections of the switch of  FIG. 1 . 
       FIG. 15  is a side elevational view of the spring employed with the rocker of  FIG. 14 . 
       FIG. 16  is a top plan view of the spring of  FIG. 15 . 
       FIG. 17  is a top plan view of the fixed contact member of the rocker of the single pole, double throw switch portion. 
       FIG. 18  is a side elevational view of the fixed contact member of  FIG. 17 . 
       FIG. 19  is a front elevational view of the fixed contact member of  FIG. 17  with the contact removed. 
       FIG. 20  is a perspective view of a cradle for the movable arms and contacts of the single pole, double throw center-off switch portion. 
       FIG. 21  is a front elevational view of the movable arms and contacts of the single pole, double throw center-off switch portion. 
       FIG. 22  is a front elevational view, partially in section, of the movable arms and contacts of  FIG. 21  mounted in the cradle of  FIG. 20 . 
       FIG. 23  is a side elevational view of the rocker of the single pole, double throw center-off switch portion of the switch of  FIG. 1 . 
       FIG. 24  is a front elevational view, in section, of the rocker of the single pole, double throw center-off switch portion. 
       FIG. 25  is a side elevational view, partially in section, of the rocker assembly and contacts of the rocker of the single pole, double throw center-off switch portion in a closed position. 
       FIG. 26  is a fragmentary top plan view of the wiring of the single pole, double throw center-off switch portion. 
       FIG. 27  is a schematic diagram of the four function electrical rocker switch of  FIG. 1 . 
       FIG. 28  is a top plan view of the movable arms and contacts of the single pole, double throw center off switch portion. 
       FIG. 29  is a top plan view of a modification of the instant device showing two single pole, double throw, center off switch sections. 
       FIG. 30  is a schematic diagram of the five function rocker switch of  FIG. 29 . 
       FIG. 31  is a top plan view of the inside of the base housing of the alternate embodiment of the switch of the present invention; 
       FIG. 32  is a top plan view of the bottom of the base housing of  FIG. 31 ; 
       FIG. 33  is a top plan view of a screw terminal of the alternate embodiment of the present invention; 
       FIG. 34  is a right side elevational view of the screw terminal of  FIG. 33 ; 
       FIG. 35  is a left side elevational view of the screw terminal of  FIG. 33 ; 
       FIG. 36  is a left side elevational view of the base housing of  FIG. 31  and a screw terminal being inserted in said housing; 
       FIG. 37  is a right side elevational view of the base housing of  FIG. 31 ; 
       FIG. 38  is a top plan view of the movable contact member of the alternate embodiment of the present invention with a screw plate being positioned relative to the movable contact member; 
       FIG. 39  is a side view of the screw plate shown in  FIG. 38   
       FIG. 40  is a side view of the movable contact member shown in  FIG. 38 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Turning now to  FIGS. 1 ,  2 ,  3  and  4 , there is shown the exterior of a four function electrical rocker switch  50  constructed in accordance with the concepts of the invention. A base  52 , as will be described below, contains the various fixed and movable contacts and the operating means therefore. Fixed to the base  52  is a cover  54  which contains three apertures  56 ,  58  and  60  (see  FIG. 13 ) through which project three rockers  62 ,  64  and  66 , respectively. A strap  68  surrounds the cover  54  and assembles it to the base  52  and provides for mounting the switch  50  to the mounting ears of a gang box (not shown) as is well known in the art. Strap  68  has flat portions  70  at each end through which extend apertures  72  to receive mounting screws  74  to fasten switch  50  to the ears of a gang box (not shown). Threaded apertures  76  accept the threaded fasteners of a cover plate (not shown) to finish the installation of the switch  50  to a gang box. Squares of insulation  78  on fasteners  74  insulate the strap  68  from the ears of the gang box. 
   Tabs  80  extend from each of the flat portions  70  at right angles to such flat portions  70  and are bifurcated at their free ends  82 . The tabs  80  extend between two raised ribs  84  on the end walls  86  of base  52  and within inturned ends  88  of raised ribs  84  (see  FIG. 5 ). The two legs  83  of the tab free ends  82  are separated and peened over the bottom edges of ribs  84  to assemble the strap  68  to base  52 . 
   The bottom  90  wall of base  52  has a series of openings  92 ,  94 ,  96 ,  98 ,  100  and  102  to receive the bared ends of individual insulated conductors (not shown). Slots  104 ,  106  and  108  are adjacent the openings  92 ,  94  and  96 , respectively, to permit the release of the conductors in the openings adjacent the slots when a small flat tool blade is inserted into a slot, as will be described in more detail below. 
   Referring now to  FIGS. 5 to 16 , there is shown the details of the rocker switch sections operated by rockers  64  and  66 . These rocker switch sections are more fully described in the aforementioned U.S. Pat. No. 5,384,441 issued Jan. 24, 1995. Rocker  66  has an upper curved surface  110  terminating at ends  112  and  114 , respectively. To place the rocker  66  in one of its two stable rest positions, the upper surface  110  is depressed at either of the ends  112  and  114 . Recesses  116  receive therein pivot pins  118  formed on the cover  54  walls which define the recesses  56 ,  58  and  60  (see  FIG. 13 ). Extending from the bottom surface  120  of rocker  66  (see  FIG. 14 ) is toggling arm  122  whose free end  124  contains a slot  126  to receive the straight portion  128  of toggle spring  130  (see  FIGS. 15 and 16 ) whose other end  132  is placed about hub  136  (see  FIG. 6 ) on the inside surface  134  of bottom  90  wall. Two spring stops  138  flank hub  136  and limit the travel of the toggle spring  130  and thus of the rocker  66  itself. Two spring rests  140  also flank hub  136 , off-set from the spring stops  138  by 90° (see  FIG. 5 ). The spring rests  140  support the free end  132  of toggle spring  130  above the inside surface  134  so that the toggle spring  130  is free to move between its two stable positions. An actuating arm  142  also extends from bottom surface  120  of rocker  66  to a free end  144  which engages the brush arm  148  of brush assembly  146 , fabricated from spring stock (see  FIGS. 8 ,  9  and  10 ). Brush arm  148  extends from brush backplate  156  to a free end at which is placed a movable contact  150 . Contact  150  is made of a silver alloy or similar material having good conductive properties and may be installed adjacent the end of brush arm  148  by welding, brazing, crimping or the like. As shown in  FIG. 10 , brush arm  148  has an initial position at about 30° up from a plane perpendicular to brush backplate  156 . As will be described below, this position prevents contact between movable contact  150  and its associated fixed contact except when the free end  144  of its associated actuating arm  142  engages it. 
   A contact arm  164  is formed with a contact surface  166  from brush backplate  156  and bent 90° with respect to the plane of the brush backplate  156  as at  168 . The end of brush backplate  156  forms a clamp wall  158  which ends in two retainer sections  160  and  162 , forming a chevron. The bared end of a conductor (not shown) is inserted through opening  92  and is positioned on contact surface  166  and held there by retainer sections  160  and  162 . This connects the entire brush backplate  156  to the same point and by that means connects to both movable contacts  150  and  154 . Thus, only a single conductor is required for both movable contacts  150  and  154  and the circuits which they form or open when rockers  64  and  66  are operated. 
   The fixed contacts are arranged upon fixed terminal assemblies, such as  170  made of resilient spring stock. There must be a separate fixed terminal assembly for each circuit that the rockers  64  and  66  form or open. The fixed terminal assemblies  170  each have a fixed terminal backplate  180  on which are formed a contact support arm  172  to which is attached, by welding, brazing, crimping or the like, a fixed contact  174  made of a silver alloy or other highly conductive metal. A contact arm  176  is partially severed from backplate  180  and bent 90° with respect to the plane of backplate  180  as at  188 . The contact arm  176  terminates in a contact surface  178 . The clamp wall  182  is formed with retainers  184  and  186  joined to form a chevron. When a solid conductor is inserted through openings  94  or  96  the bared end of the conductor generally engages the contact surface  178  and the apex between retainers  184  and  186  and is held there by the resilience of the fixed terminal assembly  170 . 
   As more fully set forth in the &#39;441 patent, when rocker  66  is positioned as it is in  FIG. 1  and end  112  is depressed and end  114  is above the cover  54 , the actuating arm  142  is not in contact with brush arm  152  and the natural resilience and the angle at which brush arm  152  is set permits movable contact  154  to remain out of engagement with a fixed contact  174  of fixed terminal assembly  170 . Toggle spring  130  rests on the right spring stop  138 . By depressing rocker  66  at end  114 , the rocker  66  begins to pivot in a clockwise direction about its pivot pins  118  (see  FIG. 13 ) and toggle spring  130  is compressed. Once the end  114  goes below its mid-point, the toggle spring  130  expands and takes a position against left spring stop  138  to define the second stable position of rocker  66 . The actuating arm  142  engages brush arm  152  and closes movable contact  154  to fixed contact  174  completing the circuit. 
   Despite the fact that both brush arms  148  and  152  are connected to a common source, the rockers  64  and  66  can be operated separately so that both circuits, controlled by brush arms  148  and  152 , can be closed or on, both open or off or one on and one off. As shown in  FIG. 27 , rockers  66  and  64  are in their off positions and brush arms  152  and  148  are in their open positions preventing the flow of current from the phase line to the loads  1  and  2  to the neutral line. 
   Turning now to  FIGS. 4 ,  5 , and  17  to  27 , there is shown the single pole, double throw rocker center-off switch operated by rocker  62 . As shown in  FIG. 5 , the chamber  190 , in which rocker  62  is located, does not have on inside surface  134  of bottom wall  90  a hub  136 , spring stops  138  or spring rests  140 . Instead it has a raised central portion  192  whose flat top portion  194  is generally surrounded by a raised wall  196  interrupted as at  198 . An aperture  200  extends through flat top portion  194 . A saddle  202  (see  FIG. 20 ) having a base  204  equal in area to the bounded flat top portion  194  of raised central portion  192  has an aperture  206  aligned with aperture  200  to receive therein a rivet  208  (see  FIG. 26 ) to fix saddle  202  to flat top portion  194  of raised central portion  192 . Saddle  202  has two side walls  210  extending from two parallel marginal edges of and perpendicular to base  204 . A tab  212  extends from the rear intermediate edge in the plane of the base  204 . The bared end of a conductor  214  introduced through opening  102  in bottom wall  90  is soldered, welded or braised to tab  212 . The side walls  210  each have slots  216  therein to define two fingers  218 ,  220 . 
   Chamber  190  also has two sets of fixed contact supports  222  and  222 ′ each made up of two C-shaped ribs extending upwardly from the inner surface  134  of bottom wall  90  and facing one another to receive the shoulders  232  of the fixed contact back plate  226 . Cleats  234  permit the backplate  226  to be positioned in the C-shaped ribs but not removed once they are in place. The fixed contact support arm  228  extends between the C-shaped ribs and supports the fixed contact  230  adjacent fixed contact support  222 . The bared end of a conductor  236  extends through opening  98  and is soldered, welded or braised to the back surface of the fixed contact back plate  226 . In a similar manner fixed contact back plate  226 ′ is positioned in the C-shaped fixed contact supports  222 ′ and fixed by its cleats  234 . The fixed contact support arm  228 ′ extends between the C-shaped ribs of fixed contact supports  222 ′ and supports the fixed contact  230 ′. The bared end of a conductor  238  extends through opening  100  and is soldered, welded or brazed to the back surface of the fixed contact back plate  226 ′. To produce a five function switching device a second chamber  190  is employed as shown in  FIG. 29 . Its schematic drawing is shown in  FIG. 30 . 
   Referring now to  FIGS. 21 ,  22  and  28 , the make-up and mounting of toggle contact  240  is described. Toggle contact  240  is fabricated from a single length of stiff metal and is formed in a single punching and forming step to provide rigid arms  242  and  244 . The arms  242  and  244  are slightly narrower than the slots  216  and can move within such slots  216 . Adjacent the center of contact  240  is an enlargement  246  which is wider than the slots  216  and which can engage the fingers  218  and  220 . The length of the enlargement  246  along the contact  240  is less than the spacing between side walls  210  and thus the contact  240  can move to a limited degree within saddle  202 . When the plunger, to be described below, rests above the enlargement  246 , the rocker  62  is in a static central position with ends  112  and  114  equally above the surface of cover  54 . This is an off position for rocker  62  and is identified as the center-off position. Fastened to the free end of arm  242  is movable contact  248  and a contact  250  is fastened to the free end of arm  244 . The contacts  248  and  250  are made of a silver alloy or other highly conductive metal and may be attached by welding, brazing, crimping or the like. In the center-off position movable contact  248  does not engage fixed contact  230  and movable contact  250  does not engage fixed contact  230 ′. 
   The toggle contact  240  is placed in the saddle  202  with enlargement  246  generally centered between side walls  210  with each of the arms  242 ,  244  extending through a separate one of the slots  216  between fingers  218 ,  220 . The arms  242 ,  244  are free to move within their associated slots  216 . As shown in  FIG. 28 , the enlargement  246  is wider than the slots  216  and thus enlargement  246  acts to limit movement of toggle contact  240  in saddle  202  as well as limit movement of the enlargement  246  in saddle  202 . The saddle  202  is connected to one line of an AC power source (not shown) by means of a conductor  214  fastened to tab  212  making the entire saddle  202  electrically hot. 
   Rocker  62  is shown in  FIGS. 23 ,  24  and  25 . Rocker  62  is different than rockers  64  and  66  and employs a spring loaded plunger which serves to fix the two stable rest positions of the toggle contact  240  and moves the arms  242  and  244  to close the movable contacts  248 ,  250  and associated fixed contacts  230 ,  230 ′, respectively. Rocker  62  has a curved top surface  110  with ends  112  and  114  and two recesses  116  to receive the pivot pins  118  of cover  54 . A hollow sleeve  252  extends downwardly as shown in  FIG. 24 . The cylindrical portion  256  of plunger  254  is positioned in and free to move within sleeve  252 . A first bore  258  in plunger cylindrical portion  256  communicates with a second bore  260  of a greater diameter to provide a shoulder  262  where bores  258  and  260  meet. A compression spring  264  extends between shoulder  262  and the interior wall  63  of rocker  62  to urge the plunger  254  out of sleeve  252 . Plunger  254  has a tapered free end  266  which engages the arms  242 ,  244  to close the movable contacts  248 ,  250  to the fixed contacts  230 ,  230 ′, respectively. The tapered free end  266  is so dimensioned that it can travel along substantially the entire length of arms  242  and  244  and within slots  216  between fingers  218 ,  220 . The plunger  254  cannot be ejected from sleeve  252  because the recesses  116  engage the pivot pins  118  to prevent rocker  62  from coming out of aperture  56  at the top and the engagement of the tapered free end  266  of the plunger  254  with the toggle contact  240  prevents ejection of plunger  254  from sleeve  252 . 
   Assuming that rocker  62  is initially in the center-off position, that is with ends  112 ,  114  at the same distance above cover  54  and the cylindrical portion  256  of plunger  254  is over the enlargement  246 , movable contacts  248  and  250  are both spaced from their associated fixed contacts  230 ,  230 ′ and both possible circuits are open. Depressing rocker  62  at end  112  causes rocker  62  to pivot in a counter-clockwise direction about pivot pins  118 . The cylindrical portion  256  of plunger  254  exits through slot  216  of saddle  202  between fingers  218 ,  220  and along arm  244 . The toggle contact  240  shifts its position so that movable contact  250  on arm  244  pivots about the base of slot  216  and engages the fixed contact  230 ′. The enlargement  246  shifts position to engage the inner surfaces of the fingers  218 ,  220  of the left sidewall  210 . Movement of the toggle contact  240  causes the movable contact  250  to wipe the surface of fixed contact  230 ′ and remove dirt, oxides and other contaminants. Since the toggle contact  240  is rigid the movement of movable contact  250  to engage fixed contact  230 ′ causes the arm  242  to pivot in a counterclockwise direction, as shown in  FIG. 25 , and further separate movable contact  248  from fixed contact  230 . Movement of rocker  62  continues until a stop  268  is engaged by the rocker  62 . At this point a solid contact exists between movable contact  250  and fixed contact  230 ′. The rocker  62  can be engaged at end  114  and moved to the center-off position or to the second closed position between movable contact  248  and fixed contact  230 . Stop  270  controls clockwise pivoting of rocker  62 . 
     FIG. 27  shows the operation of rocker  62 , as described above, in schematic form. Toggle contact  240  is shown in its center-off position and can be moved to engage fixed contact  230  to close the path from the phase line through load  3  to the neutral line or engage fixed contact  230 ′ to close the path from the phase line through load  4  to the neutral line. Thus, using the three rockers  62 ,  64  and  66  the path to both loads  1  and  2  can be closed and one of the paths to loads  3  and  4  can be closed. 
   Although a switching device is shown with one or two single pole, single throw switches and one or two single pole, double throw, center-off switches, any combination of single pole, single throw switches and single pole, double throw, center-off switches may be employed. 
     FIGS. 31–40  show an alternate embodiment of the present invention whereby the movable contact member (hereinafter “brush assembly”)  146 A and fixed contacts have apertures for receiving fasteners (e.g., screws, rivets, pins). Thus, the fixed contacts are part of screw terminal assemblies (hereinafter “screw terminals”). The screw terminals can use any well known fasteners for electrically connecting wires thereto. Thus, the screw terminals are not limited to the use of screws as fasteners. Also, a slot opening now present in the brush assembly of this alternate embodiment of the present invention allows said brush assembly also to be used as a screw terminal. That is exposed ends of electrical wiring can now be fastened to these terminals with the use of screws (or other types of fasteners) inserted through the apertures or slots. Also, the alternate embodiment of the present invention modifies base housing  52  so as to provide sidewall openings to accommodate the screw terminals as described below. 
     FIGS. 31 and 32  show top and bottom plan views of a base housing of the alternate embodiment of the present invention. Base housing  52 A has end walls  209 A and  207 A, left side wall portions  221 A,  21   5 A,  217 A and  219 A. End walls  209 A and  207 A have raised ribs  84 A with inturned ends  88 A. Base housing  52 A further has right side wall portions  213 A and  211 A and base floor  139 A. Partitions  141 A and  143 A vertically extend from base floor  139 A to form chambers  201 A,  203 A and  205 A. As in housing  52  of  FIG. 5 , each chamber contains spring stops  138  that flank hub  136 . Two spring rests  140  also flank hub  136 . The side wall portions form side wall openings  95 A,  97 A,  99 A on the left side of the base housing and side wall opening  101 A on the right side of the base housing. Along the left side wall, partitions  243 A,  245 A and  247 A form compartments in which screw terminals are disposed. Partitions  237 A,  239 A and  241 A form a compartment along the right side of the base housing  52 A for placement of the brush assembly of  FIGS. 38 and 40 . On the left side of base housing  52 A, partition  243 A has opening  263 A, partition  245 A has opening  265 A and partition  247 A has opening  267 A. On the right side of base housing  52 A, partition  239 A has opening  227 A. The openings in the partitions allow a screw or other well known fastener to extend through after having been inserted through an aperture of a screw terminal as described below. Base floor  139 A has openings  92 A,  94 A,  96 A and  98 A for receiving the bared ends of individual insulated conductors (not shown). Slots  104 A,  106 A,  108 A and  109 A are adjacent to openings  92 A,  94 A,  96 A and  98 A respectively, to permit the release of the conductors in the openings adjacent the slots when a small flat tool blade is inserted into a slot as described above. The compartments on the left side of base housing  52 A have terminal guides  251 A,  253 A,  255 A,  257 A,  259 A and  261 A. The compartments on the right side of base housing  52 A have terminal guides  223 A,  225 A,  229 A,  231 A,  233 A and  235 A and partition guide portions  237 A and  249 A. The terminal guides as shown are located on the inner side of the side wall portions. These guides are thin strips that run vertically from base floor  139 A to near the top of their respective side wall portions. The screw terminals and the brush terminals are wedged between their respective partitions, partition portions and guides during the manufacture of this alternate embodiment of the present invention. The side wall openings allow a portion of the screw terminals and a portion of the brush assembly to be exposed such that a screw (or other well known fastener) can be inserted in the openings of the screw terminals and brush assembly. 
   Referring now to  FIGS. 33–35 , there are shown different views of a screw terminal  170 A. Screw terminal  170 A has a backplate  180 A on which is formed a contact support arm  172 A to which is attached, by welding, brazing, crimping or the like, a fixed contact  174 A made of a silver alloy or other highly conductive metal. A contact arm  176 A is partially severed from back plate  180 A and bent 90° with respect to the plane of backplate  180 A at  188 A. The contact arm terminates in a contact surface  178 A. The clamp wall  182 A with retainers  184 A and  186 A joined to form a chevron. When a solid conductor is inserted through openings,  94 A,  96 A or  98 A (see  FIG. 32 ), the bared end of the conductor generally engages the screw terminal surface and the apex between retainers  184 A and  186 A and is held there by the resilience of the screw terminal assembly  170 A. Electrical conducting wires can also be fastened to screw terminal  170 A with the use of aperture  183 A where funnel  183 A extending about aperture  183 A and integral with backplate  180 A. Serrations  87 A are etched onto a portion of the outer surface  171 A of backplate  180 A so as to surround opening  183 A. The serrations are added to increase the friction between the head of a screw (not shown) inserted through opening  183 A and backplate  180 A. 
   Referring now to  FIGS. 38 and 40 , there are shown brush assembly  146 A fabricated from spring stock. Brush arms  147 A,  148 A and  152 A extend from brush backplate  156 A to free ends at which are placed contacts  149 A,  150 A and  154 A respectively. Contacts  149 A,  150 A and  154 A are made of a silver alloy or similar material having good conductive properties and may be installed adjacent the end of brush arms  147 A,  148 A and  152 A by welding, brazing, crimping or the like. A contact arm  164 A is formed with a contact surface  166 A from brush backplate  156 A and bent 90° with respect to the plane of the brush backplate  156 A at  168 A. The end of brush backplate  156 A forms a clamp wall  158 A which ends in two retainer sections  160 A and  162 A. This connects the entire brush backplate  156 A to the same point and by that means connects to all three movable contacts  149 A,  150 A and  154 A and the circuits which they form or open when rockers  64  and  66  are operated. Brush assembly  146 A has a slot  153 A about whose periphery are etched serrations  151 A. A screw plate  155 A having opening  157 A is shown being positioned behind brush assembly  146 A so that a portion of screw plate  155 A and opening  157 A are exposed through slot  153 A. Once brush assembly  146 A is positioned as shown and placed in the compartment on the right side of base housing unit  56 A, a screw (or other well known fastener) is inserted through side wall opening  101 A, slot  153 A and opening  157 A and extends through brush terminal partition slot  227 A. A side view of screw plate  155 A is shown in  FIG. 39  in which funnel  159 A is formed integrally with screw plate  155 A. 
   Referring now to  FIGS. 36 and 37 , there are shown the left side wall and right side walls respectively of base housing  52 A.  FIG. 36  shows how a screw terminal is positioned in one of the screw terminal compartments. Side wall openings  95 A,  97 A and  99 A have wider gaps near base floor  139 A of base housing  52 A. The side wall openings taper to narrower gaps as they extend toward the top of their respective side wall portions. Also, portions of the side wall surfaces that form the side wall openings are beveled so as to better engage with a fastener that has been inserted though said opening and a part of which is resting on the sidewall portions. For example, when a screw (not shown) is inserted through a side wall opening, the bottom of the screw head engages with the beveled surface. Specifically, when a screw terminal is inserted in the compartment formed by partition  243 A end wall  209 A, side wall portions  221 A and  251 A (see  FIG. 31 ), opening  183 A of the screw terminal is exposed through side wall opening  95 A. A screw (or other well known fastener) can then be inserted through sidewall opening  95 A and terminal opening  183 A. A portion of the inserted screw (not shown) extends through partition slot  263 A (see  FIG. 31 ). The bottom of the head of the inserted screw engages with the beveled surfaces of slot wall portions  221 A and  215 A and with serrations  87 A of the screw terminal. The diameter of the inserted screw is wider than the narrow gap formed by the side wall portions to prevent a fully inserted screw from traveling upwards once inserted. A similar arrangement of the screw, and screw terminal exists for side wall openings  97 A and  99 A. In like manner, brush assembly  146 A is inserted in brush terminal compartment along the right side of base housing  52 A so that slot  153 A of brush assembly  146 A is exposed through side wall opening  101 A. As previously described, screw plate  155 A is inserted behind slot  153 A of brush assembly  146 A and a screw (not shown) or other well known fastener is inserted through side wall opening  101 A, slot  153 A and screw plate opening  157 A and extends through partition slot  227 A as previously described. Thus, the alternate embodiment of the present invention allows the brush assembly and the fixed contacts to be used as terminals with the use of fasteners such as screws. 
   While there have been shown and described and pointed out the fundamental novel features of the invention as applied to the preferred embodiments as are presently contemplated for carrying them out, it will be understood that various omissions and substitutions and changes of the form and details of the device illustrated and in its operation may be made by those skilled in the art, without depending from the spirit of the invention.