Abstract:
An electrical connector assembly for terminating a free end of a metal clad cable includes a body member and an end nut. A combined friction washer/armor stop is positioned beneath the end nut. By forcing the free end of a cable against the combined friction washer/armor stop a central stop portion of the friction washer/armor stop breaks free and passes into the body member whereupon it abuts an internal shoulder of the body member thereby properly positioning the cable end within the connector assembly.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to an electrical connector for terminating armored cables and, more particularly to a connector having a novel armor stop member for properly positioning the cable end within the connector body. 
     2. Description of the Related Art Connectors used to terminate jacketed armor cable, also known as MC (metal clad) cable in the electrical industry, are made having the conductive wire(s) protected with a metal jacket and the metal jacket covered within a jacket of plastic as a waterproof outer cover. The cable&#39;s metal jacket is designed to protect the conductors and the plastic jacket is made to protect the armor and conductors from moisture. A connector used to terminate this type of cable must perform several functions. One function is to mechanically hold the armor and jacket to support the cable to a terminal box. Another function is to protect the terminal box from moisture by providing a moisture barrier around the knockout and cable jacket. The connector also mechanically terminates and houses the end of the jacket and armor. It is also important to establish a ground connection between the armor and the connector. To do this the armor end of the cable must be positioned accurately within the connector. An example of such a connector is disclosed in U.S. Pat. No. 4,647,934 issued to Hurtt. 
     Usually the manufacturer of the connector specifies that the jacket and armor be cut allowing enough length to terminate the conductors. In addition they also specify the length of the plastic jacket to be stripped form the end of the armor. A physical relationship must be established to locate the cable&#39;s armor end within the connector so that a ground connection can be made usually with a conductive spring. Most connector designs have an armor stop inside the body which has an opening large enough to pass the conductors through the connector but not allow the armor to pass thus acting as an armor stop. This locates the armor end within the connector preventing the armor end from being pushed through the fitting. It also positions the armor and jacket allowing the ground connection to be made usually by tightening a gland grounding nut(s). 
     Most connectors are designed to cover a large range of cable sizes. Some cables within the desired armor range have diameters too small to stop cable with small armor diameters. For this reason manufacturers supply an additional wire stop to locate the armor against the armor stop built within the connector thus extending the armor cable range. 
     This causes several problems for the user installing the connector because the separate armor stop may get lost. Also, when installing the armor stop the stop may be dropped or lost. The decision has to be made whether to use the separate armor stop. To do this the installer has to refer to specifications supplied on an instruction sheet supplied with the fitting, which may specify the range of the separate armor stop. He then has to measure the armor diameter and decide whether to use the separate armor stop or not. This is especially true when the armor stop is assembled within the connector, a common practice. If the installer decides not to use this armor stop assembled within the connector the installer must remove it, typically by disassembling the nut, gland and grounding spring. 
     After the MC cable is positioned within the fitting, with or without the second armor stop, the gland nut is tightened compressing and securing the cable. If the grommet turns it will put a twisting force on the cable which could turn the cable during the installation process. This results in the twisting of the cable and its conductors during installation. To prevent the grommet from turning and twisting the conductors a friction washer is usually placed between the nut and grommet to reduce the turning forces. This is usually made from a material having a low coefficient of friction such as nylon. 
     SUMMARY OF THE INVENTION 
     The present invention improves over the prior art by providing an electrical connector assembly for terminating a free end of a metal clad cable comprising a body member and having an end nut. A combined friction washer/armor stop is positioned beneath the end nut. By forcing the free end of a cable against the combined friction washer/armor stop a central stop portion of the friction washer/armor stop breaks free and passes into the body member whereupon it abuts an internal shoulder of the body member thereby properly positioning the cable end within the connector assembly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other novel features and advantages of the invention will be better understood upon a reading of the following detailed description taken in conjunction with the accompanying drawing wherein: 
     FIG. 1 is a side view, partially broken away, of an electrical connector assembly for terminating armored cable as constructed in accordance with the principles of the invention; 
     FIG. 2 is a top plan view thereof, 
     FIG. 3 is a top plan view of a novel friction washer/armor stop constructed according to the invention; 
     FIG. 4 is a cross-sectional view taken substantially along the line  4 — 4  of FIG.  3  and with a portion shown in enlarged scale; 
     FIG. 5 is a side view, partially broken away, of the connector at an initial stage of insertion of an adorned cable; 
     FIG. 6 is a side view, partially broken away of the connector at a final stage of insertion of an armored cable; and 
     FIG. 7 is a cross-sectional view of an alternative connector having a two-body design. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, and initially to FIG. 1, an electrical connector for terminating an armored cable and constructed according to the invention is designated generally by the reference numeral  10 . The connector  10  comprises, at a first end, a body member  12  configured with distal threads  14  extending from an enlarged hexagonally-shaped shoulder  16  defining flats  18  which may be used with a suitable wrench to hold the connector  10  as it is tightened with a suitable nut (not shown) in an aperture  20  of a terminal box  22 , only a portion of which is shown. Proximal threads  24  are provided on the body member  12  which threadedly receive an intermediate nut  26 . 
     The nut  26  is provided with hexagonally arranged flats  28  for receiving a suitable wrench. The nut  26  is also formed with an inclined internal surface  30  and the body member  12  is formed with an upper inclined internal surface  32 , which surfaces  30  and  32  cooperate with a circular metallic spring  34  to compress the spring  34  radially inwardly of the connector  10  as the nut  26  is tightened on the body member  12 , for purposes which will be described hereinafter. 
     An upper nut  40  having hexagonal flats  42  is received by upper threads  44  formed on the intermediate nut  26 . Internal to the nut  40  and dimensioned and configured to abut upper rim  46  of the nut  40  is an annularly shaped grommet  48 . Preferably the grommet  48  is made of a resilient rubber material. Abutting upper end  50  of the grommet  48  is a generally circular combined friction washer/arm stop  52  as will be described in detail hereinafter. The stop  52  will be described in detail hereinafter. The stop  52  is compressible against the grommet  48  by the circular rim  46  formed on the nut  40  A top plan view of the assembled connector  10  can be seen in FIG.  2 . 
     Turning now to FIGS. 3 and 4, the combined friction washer/armor stop  52  can be seen in detail. The stop  52  is preferably molded as a unitary member formed from a suitable plastic material such as NYLON. Stop  52  includes an outer annular portion  60  and an inner annular portion  62  spaced from outer portion  60  and connected thereto by a plurality of tab portions  64 . As seen in FIG. 4, the tab portions  64  are connected to the outer portion  60  at score lines  66  such that the tab portions  64  can be selectively broken away with the inner portion  62  separated from the outer portion  60 . 
     FIG. 5 illustrates a connector  10  with an armored cable  70  comprising a plurality of electrical conductors  72  extending from a sheath of metal armor  74  which has been sealed in a jacket  76  preferably of plastic or rubber. The armor  74  and jacket  76  have been prepared for terminating the cable  70  by its insertion into the connector  10 . Free end  78  of the armor  74  is shown as abutting the combined friction washer/armor stop  52  with the conductors  72  passing through circular opening  80  defined by the inner annular portion  62  of the stop  52 . 
     Upon termination of the cable  70 , and as best seen in FIG. 6, the cable  70  is manually forced into the top of the connector  10  whereupon the cable armor  74  breaks away the inner annular portion  62  of the stop  52  at the score lines  66  of the tab portions  64 . The cable  70  then inserts into the connector  10  to a point at which the annular portion  62  abuts an internal shoulder  82  of the body member  12  and stops the cable  70  from further insertion. The outer annular portion  60  remains seated against the grommet  48  and serves as a friction washer facilitating rotation of the upper nut  40  relative to the stationary grommet  48 . Once the cable  70  has been fully inserted into the connector  10 , the intermediate nut  26  may be tightened on the body member  12  causing the metal spring  34  to compress against the exposed armor  74  thereby facilitating an electrical ground between the armor  74  and the connector  10 . Finally, the upper nut  40  may be tightened on the intermediate nut  26  causing the grommet to collapse against the jacket  76  of the cable  70  thus creating a moisture proof seal between the cable  70  and the connector  10 . 
     FIG. 7 illustrates an alternative embodiment of the invention wherein a connector  90  is construed as a two-body design. The connector  90  includes a body member  92  having an upper threaded portion  94  to which a nut  96  may be screwed. However, in this arrangement an insert sleeve  98  having an inclined internal surface  100  is slidable within the body member  92  so as to compress a spring member  102  against the armor of the cable. A grommet  104  bears against the insert  98  when the nut  96  is tightened. In this embodiment the novel stop  52  may be similarly employed and operates as described above wherein annular portion  62  may break away and abut an annular shoulder portion  106  of the body member  92 . 
     The versatility of the connector  10  or  90  can now be appreciated with reference particularly to FIG.  6 . Where it is desired to terminate a cable  70  which, as shown in FIG. 6, is slightly undersized relative to the connector&#39;s internal dimensions and the size of the upper nut  40  rim  46  opening and the cable conductors  72  can freely pass through the annular portion  62 , the cable  70  may simply be terminated to the connector  10  or  90  as described above by forcing the cable  70  to break away the annular portion  62  of the combined friction washer/armor stop  52 , whereupon the portion  62  serves as an armor stop in cooperation with the shoulder  82  or  106  of the body member  12  or  92 . At the same time the connector  10  or  90  is capable of terminating a larger cable wherein the conductors  72  cannot pass through the inner portion  62  by simple manual extrication of the portion  62  using a screwdriver, for example, and then allowing the shoulder  82  or  106  alone to serve as a stop for the armor. In either case, the annular portion  60  of the friction washer/armor stop  52  remains in place to compress the grommet  48 . 
     The advantages of the novel combined friction washer/armor stop  52  can now also be appreciated. Because the connector  10  may be preassembled with the stop  52  in place, there is no likelihood that the stop  52  can become lost in use. In addition, there is no need to refer to documented specifications and measure the cable&#39;s armor to use the connector  10 . Thus, savings in installation time and avoidance of improper installation are possible. 
     While the present invention has been described in connection with a preferred embodiment thereof it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the true spirit and scope of the present invention. Accordingly, it is intended by the appended claims to cover all such changes and modifications that come within the spirit and scope of the invention.