CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application No. 60/350,657, filed Jan. 22, 2002. 


   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to pendant suspension systems for luminaires, and more particularly to a continuously adjustable cable suspension system for a suspended linear style track lighting luminaire having two suspension points at either end of the luminaire. 
   2. Description of Prior Art 
   Suspended linear style track lighting luminaires are typically provided with fixed length rigid stems for attaching the luminaries to lighting track. For example, ½ inch diameter pipe is often used for the stems for such pendant mounting type luminaires. However, vertical height adjustment of such rigid pendant systems is limited by the available lengths of the fixed length stems, or requires cutting and rethreading the stems to the desired length. Further, once installed, additional vertical height adjustment of the luminaire requires replacement of the stems with stems of the desired length. 
   Additionally, since track lighting luminaires are typically aimable, the pendant mounting system requires balance and stability to counteract the moment arms created when pivoting the luminaire for aiming. 
   BRIEF SUMMARY OF THE INVENTION 
   Thus, it is an object of the present invention to provide a suspended linear style track lighting luminaire with a continuously adjustable pendant system for attaching the luminaire to the lighting track. 
   It is a further object of the invention to provide a pendant system which allows vertical height adjustment of the luminaire after installation without addition or replacement of any of the pendant system components. 
   It is yet a further object of the invention to provide a pendant system which provides balance and stability to the luminaire to counteract the moment arms created when pivoting the luminaire for aiming. 
   These and other objects are met through a pendant system having twin suspension assemblies, with each assembly having a track adapter body for engaging a lighting track, a flexible support element gripper attached to the track adapter body, and an elongated flexible support element having two ends, where a first end is held by the track adapter body and the second end is adjustably held by the flexible support element gripper, where each of the flexible support elements forms an adjustable length loop from which each end of the luminaire may be suspended. 
   The objects are further met by a pendant system having rotation housings rotatably connected each end of a luminaire, defining an axis about which the luminaire may rotate, where each rotation housing has a channel through which a flexible support element loop suspends the luminaire. Each flexible support element loop is formed from a flexible support element having two ends, with both ends being held by a suspension assembly for attaching to a lighting track. 


   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       FIG. 1  is a perspective view of a linear style track lighting luminaire suspended on a pendant system of the present invention. 
       FIG. 2  is a perspective view of a suspension assembly and cable of a pendant system of the present invention as it is installed into a section of lighting track. 
       FIG. 3  is another perspective view of a suspension assembly and cable of a pendant system of the present invention as it is installed into a section of a lighting track. 
       FIG. 4  is a perspective view of a suspension assembly of a pendant system of the present invention, with excess cable stored on a take-up section of the suspension assembly. 
       FIG. 5  is another perspective view of a suspension assembly of a pendant system of the present invention, further having a suspension assembly cover. 
       FIG. 6  is a perspective view of a suspension assembly of a pendant system of the present invention. 
       FIG. 7  is a partial front view of the pendant system, track, and luminaire of FIG.  1 . 
       FIG. 8  is a partial perspective view of the pendant system and luminaire of  FIG. 1   
       FIG. 9  is an exploded partial perspective view of the pendant system and luminaire of FIG.  1 . 
   


   DETAILED DESCRIPTION OF THE INVENTION 
   FIGS.  1  and  7 - 9  show a suspended linear style track lighting luminaire  10  attached to a lighting track  12  by a pendant system  14  of the present invention. The pendant system  14  is comprised of twin suspension assemblies  16  which engage the lighting track  12  and provide support to each end of the luminaire  10 . Each suspension assembly  16  has a track adapter  18  and a cable  20 . Each cable  20  is held at both ends by the respective track adapter  18 , thus forming a loop. Each loop then supports an end of the luminaire  10 . 
   The cable of the preferred embodiment of the invention is a {fraction (1/32)} inch stainless steel aircraft type cable having 7×7 construction (7 twisted strands of 7 twisted strands), which provides the strength, resistance to the elements and appearance desired for the pendant system application. However, those of skill in the art will recognize that other equivalent flexible support elements may be substituted without altering the spirit or the scope of the invention described herein. 
   As also shown in FIGS.  1  and  7 - 9 , a rotation housing  22  extends outward from each end of the luminaire  10 . The luminaire  10  hangs by the rotation housings  22  from the loops of each cable  20 . 
   As shown in  FIG. 9 , a channel  24  is formed through each rotation housing  22 . In the embodiment shown, the channels  24  are U-shaped and have entry points located along opposite sides of each rotation housing  22 . Each cable  20  runs through the respective channel  24  and a cover  26  closes a side of the channel  24  in order to hold the cable  20  in the channel  24 . Further, each channel  24  is large enough to allow the corresponding cable  20  to slide freely within the channel  24  so that the luminaire  10  will slide along the cables  20  to the bottom of the loops. Thus, both ends of each cable  20  support each end of the luminaire  10  in a balanced manner. Further, since the luminaire will always slide to the bottom of the loops, the pendant system is suitable for use with sloped and other ceiling configurations. 
   The rotation housing  22  separates the entry points into each channel  24  approximately the same distance that the ends of the cable are separated by the track adapter  18  creating a two point suspension at each end of the luminaire  10 . This two point suspension provides balance and stability to the suspension of the luminaire  10  by creating multiple axes of rotation which serve to resist any rotational moments that may be created about any one of the axes alone. 
   Each rotation housing  22  is rotatably connected to the luminaire  10  through an eyelet type rotation joint which allows free rotation of the luminaire about an axis defined by the rotation housings  22  located at each end of the luminaire  10 . Thus, the luminaire  10  may be rotated about the rotational axis for aiming the light output of the luminaire  10  a full 360 degrees around the rotational axis. In practice, rotation stops are provided within the eyelet type rotation joint in order to prevent rotation through an arc greater than 360 degrees, and damage to the electrical wiring within the luminaire  10 . 
   Also shown in  FIG. 1  is a power adapter  28  and the power cord  30  which supply power from the lighting track  12  to the luminaire  10 . 
   As shown in  FIGS. 2 through 6 , each track adapter  18  has a body  32  and a cover  34 . 
   As best seen in  FIGS. 2 and 6 , each track adapter body  32  has a track adapter head section  36 , an upper flange  38 , a cable take-up section  40 , and a base section  42  which retains the ends of the cable  20 . Each track adapter head section  36  has track engaging ears  44 . Each base section  42  has a channel  46  which accepts and holds a hex nut  48  in a stationary position. Aligned with and under the hex nut  48 , each base section  42  further has a first hole  43 . Spaced from each first hole  43 , each base section  42  has a second hole  45 . A flexible support element gripper, such as a cable lock device  50 , having a threaded cylindrical body is threaded into each hex nut  48  through the corresponding first hole  43 . A first end  51  of each cable  50  is fed through the corresponding second hole  45  and held from being pulled through the hole by a copper stop  52  crimped thereto. A second end  49  of each cable  20  is fed through and held by the corresponding cable lock device  50 . 
   Turning now to  FIGS. 2 and 3 , the track adapter body  32  is attached to the track  12  by inserting the track adapter head  36  into the central channel  53  of the track cavity and rotating the track adapter body 90 degrees such that the track engaging ears  44  mechanically engage the rails  55  of the track  12 . Thus, the track adapter body  32  is securely held by the track  12 . 
   As shown in  FIG. 3 , following attachment of the track adapter body  32  to the track  12 , the cable lock device  50  may be utilized to adjust the vertical height of the luminaire  10 . The cable lock device  50  allows the cable  20  to be drawn through in one direction while preventing it from being pulled back through in the other direction unless a release mechanism is activated. 
   For instance, the cable lock device  50  of the embodiment shown herein is commercially available as Reutlinger Grip Lock Systems™ part number 12-M8, which utilizes a ball bearing mechanism inside of the device to wedge against the cable  20  when a force is applied to pull the cable out of the device, while easing when the cable is pulled into the device or the plunger  54 , acting as a release mechanism, is depressed. One of skill in the art will recognize that other cable types and cable lock devices may be utilized without departing from the spirit or the scope of the invention described herein. 
   Thus, as shown in  FIG. 3 , the first end  49  of the cable  50  may be pulled through the cable lock device  50  to shorten the amount of cable in the loop and raise the vertical height of the luminaire  10 . The luminaire  10  will balance itself at the bottom of the loop via the free movement of the cable in the rotation housing channel  24  (FIG.  9 ). Thusly, the vertical height of the luminaire is continuously adjustable for installation of the luminaire  10  as desired. 
   Further, as shown in  FIG. 4 , excess cable  10  may be wrapped around the take-up section  40  for future adjustment of the vertical height of the luminaire  10 . V-shaped grooves  56  are supplied on either side of the track adapter body  32  for use as a cleat to lock the cable  10  in place. Thus, securing the cable  10  in the V-shaped grooves  56  will prevent an unintended release of the cable lock device  50  by an accidental depression of the spring loaded plunger  54 . 
   The cover  34  slides up the cable  10  and over the track adapter body  32  and mates with the track adapter upper flange  38  to enclose the mechanical components of the track adapter body  32 , thus giving the track adapter  18  a finished and aesthetically pleasing appearance. 
   This detailed description of the invention, including specific elements and configurations of elements, shall not be construed as a limitation of the invention, as it will be readily apparent to those skilled in the art that design choices may be made changing the configuration of the luminaire pendant system without departing from the spirit or scope of the invention. For instance, alternative ceiling interface arrangements, such as a fixed mount other than with a lighting track, or use of the pendant system with a luminaire other than a linear fluorescent track luminaire, would be equivalent embodiments to the embodiment of the invention disclosed herein.
A pendant suspension system provides a continuously adjustable cable suspension system for luminaires. The cable suspension system has twin suspension assemblies, each comprising a cable held at both ends by a track adapter so as to form a downwardly depending loop. A luminaire is affixed on each end to the suspension system at the loop. The vertical height of the luminaire can be adjusted by pulling one end of the cable through the track adapter. Further, the luminaire can be connected to the loop through a rotation housing that permits rotational adjustment of the luminaire. Thus, the combination suspension system and rotation housing permits continuous vertical and rotational adjustment of an attached luminaire.