Abstract:
An electrical fitting having an improved arrangement on the trailing end for attaching electrical cables thereto. A connector body includes a trailing opening and an intermediate flange. An open channel extends from the trailing opening to the intermediate flange and includes a bottom. A bridge on the connector body adjacent the trailing opening is adapted to receive a tandem tang secured thereto. The tandem tang includes a common middle section and a leading tang and a trailing tang extending therefrom. Cable grabbing ends are provided on both the leading and trailing tangs. The leading and trailing tangs extend from outward of the connector body into the open channel. The tangs are of substantial length and are cantilevered over such a distance so as to enable easy insertion of cable within the trailing opening. The open channel permits additional space for flexing of the tangs of the tandem tang to further ease insertion of cables into the fitting. Bend lines on the leading and trailing tangs direct the cable grabbing ends toward an inserted cable and thereby hold the cable against the bottom of the open channel.

Description:
This application is a Continuation-In-Part of U.S. patent application Ser. No. 11/300,859 filed Dec. 15, 2005 and still pending. 

   FIELD OF THE INVENTION 
   This invention relates to fittings for connecting electrical cables to an electrical panel or box and specifically to an electrical fitting having an improved arrangement on the trailing end for receiving an electrical cable or conduit. 
   BACKGROUND OF THE INVENTION 
   Several prior art connectors have been proposed for the attachment of electrical cables or conduits to panels or electrical boxes. Some of these include a tubular body with a cavity on the trailing end and a split ring that is inserted within the cavity. Typically the split ring includes one or more cable gripping tangs for securing a cable to the trailing end of the connector. As a result of the limited space within the cavity, the length of the cable gripping tangs is limited. Thus the cable gripping tangs must be relatively short, making the tangs stiff and less flexible, which translates to a higher than desired amount of force required to insert a cable into the trailing end of the electrical connector. 
   An electrical fitting having an improved arrangement on the trailing end for the attachment of electrical cables was disclosed in co-pending U.S. application Ser. No. 11/300,859, which is commonly owned by the assignee of the present invention and the contents of which are incorporated herein in their entirety by reference thereto. Instead of the split ring being located within the tubular body as shown in the prior art, the improved arrangement included single or tandem cable gripping tangs that are fastened externally to the tubular body and therefore are easily accessible. 
   The present invention improves upon the electrical fitting of U.S. application Ser. No. 11/300,859 by providing increased space to allow for flexing of the cable gripping tangs. The movement of the cable gripping tangs is therefore not as restricted when a cable is secured thereto to the trailing end of the connector, thereby allowing easier insertion of electrical cables and enabling the electrical fitting to accommodate a wider range of cable sizes. 
   SUMMARY OF THE INVENTION 
   The invention is an electrical fitting having an improved arrangement on the trailing end for attaching electrical cables thereto. A connector body includes a trailing opening and an intermediate flange. An open channel extends from the trailing opening to the intermediate flange and includes a bottom. A bridge on the connector body adjacent the trailing opening is adapted to receive a tandem tang secured thereto. The tandem tang includes a common middle section and a leading tang and a trailing tang extending therefrom. Cable grabbing ends are provided on both the leading and trailing tangs. The leading and trailing tangs extend from outward of the connector body into the open channel. The tangs are of substantial length and are cantilevered over such a distance so as to enable easy insertion of cable within the trailing opening. The open channel permits additional space for flexing of the tangs of the tandem tang to further ease insertion of cables into the fitting. Bend lines on the leading and trailing tangs direct the cable grabbing ends toward an inserted cable and thereby hold the cable against the bottom of the open channel. 
   OBJECTS AND ADVANTAGES 
   Several advantages are achieved with the electrical fitting of the present invention, including:
         (1) The fitting will typically accommodate cables of multiple trade sizes. This enables a few sizes of fittings to accommodate the entire range of standard cable sizes available and therefore reduces stocking requirements of the fittings.   (2) The fitting includes gripping members that are located external to the tubular body, thereby permitting longer gripping members that allow insertion of cables with less force than is typically required in prior art fittings.   (3) The increased length of the gripping members permits them to be cantilevered over a greater distance, thereby increasing their flexibility and enabling easier insertion of cables.   (4) An internal ring with gripping members is not required, thereby simplifying the production of the fitting and reducing the cost of manufacture.   (5) As a result of the increased length and flexibility of the gripping members, cables can easily be released when such is desired.   (6) A larger open area within the tubular body provides further space for flexing of the clip legs and therefore further enhances ease of cable insertion.       

   These and other objects and advantages of the present invention will be better understood by reading the following description along with reference to the drawings. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view from the trailing end of an electrical fitting according to the present invention. 
       FIG. 2  is a side view of the electrical fitting of  FIG. 1 . 
       FIG. 3  is a front view of the electrical fitting as taken from line  3 — 3  of  FIG. 2 . 
       FIG. 4  is a sectional view of the electrical fitting taken along line  4 — 4  of  FIG. 2 . 
       FIG. 5  is a side view of the electrical fitting taken along line  5 — 5  of  FIG. 3 . 
       FIG. 6  is a top view of the electrical fitting of  FIG. 1 . 
       FIG. 7  is a front view of the electrical fitting taken from line  7 — 7  of  FIG. 6 . 
       FIG. 8  is a side view of an insert that is used in conjunction with the electrical fitting of  FIG. 1 . 
       FIG. 9  is an end view of the insert taken from line  9 — 9  of  FIG. 8 . 
       FIG. 10  is a perspective view of a clip member that forms a portion of the electrical fitting of  FIG. 1 . 
       FIG. 11  is a side view of the clip member of  FIG. 10 . 
       FIG. 12  is an end view of the clip member taken from line  12 — 12  of  FIG. 11 . 
       FIG. 13  is a sectional view of the clip member taken along line  13 — 13  of  FIG. 12 . 
       FIG. 14  is a top view of the clip member of  FIG. 11 . 
       FIG. 15  is a plan view of a blank that is used to form the clip member of  FIG. 10 . 
       FIG. 16  is a sectional view of the electrical fitting of  FIG. 1 . 
       FIG. 17  is a sectional view of the electrical fitting with a metal clad electrical cable secured therein into the fitting. 
       FIG. 18  is a sectional view of the electrical fitting similar to  FIG. 17  but with a larger trade size electrical cable secured therein into the fitting. 
       FIG. 19  is a perspective view from the leading end of a tubular body that forms a portion of electrical fitting of  FIG. 1 . 
       FIG. 20  is a perspective view from the trailing end of the tubular body of  FIG. 19 . 
       FIG. 21  is a perspective view from the trailing end of the preferred embodiment of an electrical fitting according to the present invention. 
       FIG. 22  is a side view of the connector body portion of the electrical fitting of  FIG. 21 . 
       FIG. 23  is a front view of the connector body as taken from line  23 — 23  of  FIG. 22 . 
       FIG. 24  is a top view of the connector body of  FIG. 22 . 
       FIG. 25  is a sectional view of the connector body of  FIG. 21 . 
       FIG. 26  is a sectional view of the electrical fitting of  FIG. 21  with a metal clad electrical cable secured therein into the fitting. 
       FIG. 27  is a sectional view of the electrical fitting of  FIG. 21  but with a larger trade size electrical cable secured therein into the fitting. 
       FIG. 28  is a perspective view from the leading end of a preferred embodiment of a connector body that forms a portion of electrical fitting of  FIG. 21 . 
       FIG. 29  is a perspective view from the trailing end of the connector body of FIG.  28 . 
       FIG. 30  is a side view of a tandem tang that forms a portion of the electrical fitting of  FIG. 21 . 
       FIG. 31  is an end view of the tandem tang taken from line  31 — 31  of  FIG. 30 . 
       FIG. 32  is a sectional view of the tandem tang taken along line  32 — 32  of  FIG. 31 . 
       FIG. 33  is a top view of the tandem tang of  FIG. 30 . 
       FIG. 34  is a plan view of a blank that is used to form the tandem tang of  FIG. 30 . 
   

   INDEX TO REFERENCE NUMERALS IN DRAWINGS 
   
       
       
         
             30  electrical fitting 
             32  tubular body 
             34  leading portion 
             36  trailing portion 
             38  bore 
             39  raised area of tubular body 
             40  clip member 
             42  base portion 
             44  central axis 
             45  cylindrical volume 
             46  leg 
             46 A first leg 
             46 B second leg 
             47  cavity 
             48  cantilever point 
             50  end portion of leg 
             52  top portion of leg 
             54  intermediate portion of leg 
             56  aperture in clip member 
             58  aperture in tubular body 
             60  opening 
             62  fastener 
             64  leading end 
             66  trailing end 
             68  top wall of trailing portion 
             70  top wall of leading portion 
             72  central flange 
             74  end flange of tubular body 
             76  thick wall section 
             78  partial closure 
             80  opening in partial closure 
             82  edge 
             84  insert 
             86  end flange of insert 
             88  smooth seat 
             90  necked-down nose section 
             91  center bore of insert 
             92  outer sheath 
             93  peak 
             94  groove 
             96  first cable 
             98  second cable 
             100  lower end of leg 
             102  semicircular notch 
             104  blank 
             106  bend line 
             110  electrical fitting 
             112  connector body 
             114  leading end of connector body 
             116  trailing end of connector body 
             118  intermediate flange 
             120  leading opening 
             122  trailing opening 
             124  tandem tang 
             126  fastener 
             128  open channel 
             130  bottom of open channel 
             132  bridge 
             133  outwardly extending ramp 
             134  inclined surface of bridge 
             136  aperture in inclined surface 
             138  bore 
             140  leading tang 
             142  trailing tang 
             144  common middle section 
             146  cable grabbing end 
             148  aperture in common middle section 
             150  first right angle bend 
             154  second right angle bend 
             158  bend line 
           D 1  outer dimension of the intermediate flange 
           θ angle of intermediate portion of leg with respect to central axis 
         
       
     
  
   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIG. 1  there is shown a first embodiment of the present invention, an electrical fitting  30  having an improved arrangement for the securing of electrical cables thereto. The electrical fitting  30  includes a continuous tubular body  32  including a leading portion  34 , a trailing portion  36 , and a bore  38 . A raised area  39  extends in one direction from the tubular body  32 . Secured externally to the trailing portion  36  of the tubular body  32  is a clip member  40 , with the clip member  40  including a base portion  42  at which it is secured to the tubular body  32 . 
   Referring to  FIG. 16 , the bore  38  of the tubular body  32  includes a central axis  44  defined by the leading portion  34 . The central axis  44  of the bore  38  is the axial center of the leading portion  34 . A cylindrical volume  45  surrounds the central axis  44  within the leading portion  34 . Within the raised area  39  of the trailing portion  36  is a cavity  47 . The cavity  47  provides additional volume between the raised area  39  and the central axis  44  and thereby creates a larger volume within the trailing portion  36  than the cylindrical volume  45  of the leading portion  34 . At least one leg  46  extends from the base portion  42  of the clip member  40 . The leg  46  extends from the raised area  39  of the tubular body  32  into the bore  38 . The leg  46  is cantilevered from a point  48  exterior of the tubular body  32 , which is the cantilever point  48  where the base portion  42  of the clip member  40  joins the leg  46 . The leg  46  extends substantially to the central axis  44  of the tubular body  32 . The leg  46  includes an end portion  50  with the end portion  50  being preferably within 30 degrees of perpendicular with respect to the central axis  44  of the tubular body  32 . Each leg  46  includes a top portion  52  and an intermediate portion  54 . The intermediate portion  54  of each leg  46  is preferably at an angle θ of between 20 and 60 degrees with respect to the central axis  44  of the bore  38 , and, more preferably, at an angle θ of 40 degrees with respect to the central axis  44  of the bore  38 . 
   As shown in  FIGS. 11–14 , the clip member  40  has two legs  46 , including a first leg  46 A and a second leg  46 B. The base portion  42  of the clip member  40  includes an aperture  56  therein. Additionally, as shown in  FIG. 6 , the trailing portion  36  of the tubular body  32  includes an aperture  58  therein, which may be a smooth aperture or threaded, and an opening  60  positioned near the aperture  58 . 
   With reference to  FIG. 16 , the clip member  40  is secured to the tubular body  32  by a fastener  62  secured through the aperture  56  in the clip member  40  into the aperture  58  in the trailing portion  36  of the tubular body  32 . The tubular body  32  includes a leading end  64  and a trailing end  66 . When the preferred embodiment of the clip member  40  is secured to the tubular body  32 , the first leg  46 A extends directly into the bore  38  of the tubular body  32  at the trailing end  66 . The second leg  46 B extends through the opening  60  and into the bore  38  of the tubular body  32 . With the clip member  40  secured to the tubular body  32  to form the electrical fitting  30  of the present invention, as shown in  FIG. 16 , the base portion  42  extends between the first leg  46 A and the second leg  46 B and the first leg  46 A and the second leg  46 B extend from the base portion  42  at a substantially constant distance from each other thereby forming parallel legs  46 A and  46 B. The raised area  39  of the tubular body  32  enables the electrical fitting  30  to accommodate legs  46 A and  46 B of longer length than comparable prior art fittings, and the greater length increases the flexibility of the legs  46 A and  46 B thereby allowing them to flex upwards when contacted by a cable inserted therein (not shown) and admit passage of the cable while imparting very little resistance to its forward advance into the bore  38 . 
   Referring to  FIGS. 4 and 5 , the tubular body  32  includes a top wall  68  on the trailing portion  36  and a top wall  70  on the leading portion  34  with the top wall  68  of the trailing portion  36  extending farther from the central axis  44  than the top wall  70  of the leading portion  34 . As shown in  FIG. 4 , the top wall  68  of the trailing portion  36  is substantially flat. The tubular body  32  further includes a central flange  72  between the trailing portion  36  and the leading portion  34  and an end flange  74  on the leading end  64  of the tubular body  32 . As shown in  FIG. 5 , the aperture  58  in the trailing portion  36  of the tubular body  32  is formed in a thick wall section  76 . 
   With reference to  FIG. 7 , the tubular body  32  further includes a partial closure  78  on the leading end  64 . The partial closure  78  includes an opening  80  therein. Edges  82  on the partial closure  78  surround the opening  80 . 
   A tubular insert  84  which may be used with the electrical fitting of the present invention is depicted in  FIGS. 8 and 9 . The insert  84  includes an end flange  86 , a smooth seat  88 , a necked-down nose section  90 , and a center bore  91 . As shown in  FIGS. 2 and 3 , the insert  84  may be pressed into the opening  80  of the partial closure  78  on the leading end  64  of the tubular body  32  to substantially cover the edges  82  of the opening  80 . The insert  84  acts to protect the outer sheaths of any wiring (not shown) that is later advanced through the opening  80  within the partial closure  78  of the tubular body  32 . The insert  84  is preferably molded of plastic. 
   As shown in  FIGS. 19 and 20 , the thick wall section  76  including the aperture  58  therein is located at the trailing end  66  of the tubular body  32 . As depicted in  FIG. 19 , the plastic insert  84  is secured in the leading end  64  of the tubular body  32 . 
   The tubular body  32  is constructed of a conductive metal such as steel, zinc, galvanized steel, or aluminum. The tubular body  32  of the present invention is typically formed by die-casting and die-casting alloys are the most preferred material of construction. A most preferred material of construction for the tubular body is zamak™, a casting alloy comprised mainly of zinc alloyed with aluminum, magnesium, and copper and available from Eastern Alloys, Maybrook, N.Y. By constructing the tubular body of zamak™ or other appropriate metals, the tubular body will be electrically conductive and provide good continuity throughout the fitting. 
   Referring to  FIG. 12 , the lower end  100  of each leg  46  of the clip member  40  includes a semicircular notch  102 . The semicircular notch  102  is centered on the lower end  100  of the leg  46  and approximates the outer curvature of the portion of a cable (not shown) that the lower end  100  of the leg  46  will seat within. The leg  46  seats in a groove of the cable (see  FIG. 16 ). 
   With reference to  FIG. 15 , the clip member is preferably formed from a blank  104  of metal. Bend lines  106  are shown on the blank  104  to depict the areas in which the blank  104  will be bent to form the preferred embodiment of the clip member having the shape shown in  FIG. 10 . 
   The clip member  40  is preferably constructed of spring steel and is electrically conductive. Constructing the tubular body  32  of zinc alloy and the clip member  40  of spring steel enables the electrical fitting  30  to establish electrical continuity between the metallic-sheathed cable or conduit and the panel or electrical box to which it is attached. 
   For operation of the present invention, the reader is directed to  FIGS. 17 and 18 . As previously mentioned in the objects and advantages section, the electrical fitting  30  of the present invention will typically accommodate two trade sizes of cable, which has several advantages in production and stocking requirements. The electrical fitting is especially useful for securing MC (metal clad) or armored cable to a panel or electrical box. MC or armored cables include a convoluted outer surface  92  consisting of peaks  93  and grooves  94  such as shown in  FIG. 17 . As the electrical fitting is capable of accepting two trade sizes of cable, the parallel legs  46  are capable of engaging one or more of the grooves  94  of the electrical cable depending on the trade size. 
   With reference to  FIG. 17 , a first cable  96  is inserted within the bore  38  of the tubular body  32  and, as a result of the flexibility imparted to the legs  46 A and  46 B by the length and angle of the legs, is engaged by at least one of the legs  46 A of the electrical fitting  30  in one of the grooves  94  of the first cable  96 . The legs  46 A and  46 B have a certain degree of flexibility, have a certain length, and are at an angle that allows them to flex upwards as a cable is inserted into the fitting  30 . As the cable  96  is pushed into the fitting  30 , the length and angle of the legs  46 A and  46 B with respect to the central axis  44  impart enhanced flexibility to the legs  46 A and  46 B and enables the first leg  46 A to flex upwards and admit passage of the cable  96  with very slight resistance. Forward insertion of the cable  96  is limited by the partial closure  78  at the leading end  64  of the fitting  30 . Once the cable  96  is fully inserted into the fitting  30 , as shown in  FIG. 17 , the cable  96  is securely held by the first leg  46 A. As a result of the first leg  46 A seating in a groove  94 , and the angle of the first leg  46 A with respect to the central axis  44 , the cable  96  is held very securely and cannot be removed by a backward force placed upon the cable  96 . The electrical fitting  30  of the present invention effectively grasps a cable  96  by the use of a single leg  46 A and  46 B from one side of the fitting  30 , versus prior art connectors (not shown) that employ multiple gripping members from multiple sides of the fitting. The legs  46 A and  46 B contact with the cable  96  and  98  provides the necessary electrical continuity from the cable  96 ,  98  to the electrical fitting  30  and to the panel or electrical box (not shown). 
   With reference to  FIG. 18 , an electrical fitting  30  of the same size as that shown in  FIG. 17  is capable of accommodating a second cable  98  of a larger trade size. The larger trade size or smaller gauge cable  98  is of a larger diameter than that shown in the previous example. The second cable  98  is inserted within the bore  38  of the tubular body  32  and, as a result of the flexibility imparted to the legs by the length and angle of the legs, is engaged by both legs  46 A and  46 B of the electrical fitting  30 . As the distance between the parallel legs  46 A and  46 B substantially matches the distance between successive grooves  94  of the electrical cable  98 , the two legs  46 A and  46 B seat in successive grooves  94  of the cable  98 . The flexibility of the legs  46 A and  46 B and the spacing between them enables each leg to find a groove  94  on the cable  98 . As the cable  98  is pushed into the fitting  30 , the length and angle of the legs  46 A and  46 B with respect to the central axis  44  impart enhanced flexibility to the legs  46 A and  46 B and enables both legs  46 A and  46 B to flex upwards and admit passage of the cable  98  with very slight resistance. Forward insertion of the cable  98  is again limited by the partial closure  78  at the leading end of the fitting  30 . Once the cable  98  is fully inserted into the fitting  30 , as shown in  FIG. 18 , the cable  98  is securely held by both legs  46 A and  46 B. As a result of the legs  46 A and  46 B seating in the grooves  94 , and the angle of the legs  46 A and  46 B with respect to the central axis  44 , the cable  98  is held very securely and cannot be removed by a backward force applied thereto. However, if it is necessary to remove the cable from the fitting, the cable  98  can easily be removed by unscrewing the fastener  62  and removing the clip member  40 . As compared to prior art fittings, the clip member  40  of the present invention is thicker and more stable, and the legs  46 A and  46 B are longer so that the electrical fitting  30  of the present invention will accommodate two sizes of cable. The length of the legs  46 A and  46 B ensures that they are cantilevered over a longer distance than the analogous gripping members of prior art connectors. 
   The leading end of the electrical fitting can be secured to a panel (not shown) by an attachment arrangement such as the spring steel adapter (14) disclosed in U.S. Pat. No. 6,335,488 or the spring steel adapter (20) disclosed in U.S. Pat. No. 5,266,050, commonly referred to as snap fittings, both of which patents their entireties are incorporated herein by reference. 
   Alternatively, the attachment arrangement may include threads on the leading portion of the tubular body and a nut (not shown) for engaging the threads such as the standard lock nut (70) disclosed in U.S. Pat. No. 6,596,939, the entirety of which is incorporated herein by reference. 
   Referring to  FIG. 21 , there is shown a preferred embodiment of an electrical fitting  110  for connecting electrical cable to a panel or an electrical box (not shown). The electrical fitting  110  includes a connector body  112  including a leading end  114  and a trailing end  116  separated by an intermediate flange  118 . The connector body  112  includes a leading opening  120  (see  FIG. 23 ) at the leading end  114  and a trailing opening  122  at the trailing end  116 . The intermediate flange  118  extends transversely beyond the connector body  112  by an amount sufficient to prevent the fitting from going into an electrical box outlet hole (not shown) when the leading end  114  of the connector body  112  is inserted therein. The electrical fitting  110  includes a tandem tang  124  is secured thereto by a fastener  126 . 
   The leading end  114  of the electrical fitting  110  can be secured to a panel or an electrical box (not shown) by an attachment arrangement such as the aforementioned spring steel adapters disclosed in U.S. Pat. No. 6,335,488 or U.S. Pat. No. 5,266,050 or by the threaded nose portion and locknut shown in U.S. Pat. No. 6,596,939. 
   With reference to  FIGS. 24 and 25 , the trailing end  116  of the connector body  112  includes an open channel  128  that extends from the trailing opening  122  to the flange  118 . The open channel  128  includes a bottom  130  therein. The connector body  112  further includes a bridge  132  adjacent the trailing opening  122 . Two outwardly extending ramps  133  extend from the part of the open channel  128  adjacent the flange  118  outwardly and rearwardly to provide the support for bridge  132 . Adjacent the trailing end opening  122  bridge  132  extends transversely at the top of the outermost part of the ramp  133  to bridge the open channel  128 . The bridge  132  bridges the open channel  128  and extends transversely beyond the outer dimension D 1  of the intermediate flange  118 . The bridge  132  includes an inclined surface  134  and an aperture  136  therein. The connector body  112  also includes a bore  138  extending from the flange  118  to the leading opening  120 . 
   Referring to  FIGS. 30–34 , the tandem tang  124  includes a leading tang  140 , a trailing tang  142 , and a common middle section  144 . The leading tang  140  and trailing tang  142  each include a cable grabbing end  146 . An aperture  148  is provided in the common middle section  144  of the tandem tang  124  for receiving a fastener (see  FIG. 21 ) therein for securing the tandem tang  124  to the connector body  112 . The common middle section  144  of the tandem tang  124  is bent at one end at a first right angle  150  to form the leading tang  140  and at the opposite end at a second right angle  154  to the trailing tang  142 . The leading tang  140  and the trailing tang  142  each include a bend line  158  as shown in  FIG. 34 . 
   With reference to  FIGS. 26–27 , the bend lines  158  on both the leading tang  140  and the trailing tang  142  direct the cable grabbing end  146  towards the cable  92  thereby holding the cable against the bottom  130  of the open channel  128 . The inclined surface  134  of the bridge  132  is included on the connector body  112  for receiving and attaching the common middle section  144  of the tandem tang  124 . The leading tang  140  and trailing tang  142  each include a cable grabbing end  146  for contacting and holding a cable  96  against the bottom  130  of the open channel  128 . 
   Although the description above contains many specific descriptions, materials, and dimensions, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.