Abstract:
A continuously installable/removable collector trolley includes a plurality of selectively extendable and retractable bearing assemblies. The bearing assemblies may be retracted to permit insertion and removal of the trolley into a conductor bar track at any point along the track. The bearing assemblies may then be extended to secure the trolley within the track, and to permit the bearings to roll along the track, permitting movement of the trolley.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to enclosed conductor bar systems. More specifically, the present invention provides a conductor bar system providing electrical power to moving equipment, having a trolley that may be installed or removed at any point in the conductor bar system. 
     2. Description of the Related Art 
     Presently existing conductor systems for moving equipment include trolleys that may only be safely installed or removed at either end of the track or in specially constructed track sections including a door. 
     Within a conductor bar system using door track sections, each door track&#39;s section includes a pair of hinged doors in the bottom of the track, thereby permitting insertion and removal of trolleys. This design raises the issues of securely locking the doors, and accurately aligning the doors with the remainder of the track to form an uninterrupted track for the trolleys. 
     A typical plastic enclosed system includes a housing of extruded plastic, with the copper conductor bars encapsulated directly into the housing. Trolleys must be installed or removed from such systems only at one end of the track. If removal of the trolley from an end of the track is not possible, the only other alternative is to pry the track open, which raises safety concerns. 
     Accordingly, an enclosed conductor bar system having a trolley that may be installed or removed at any point along the track is desired. Such a system would result not only in ease of manufacture and installation, but also ease in reconfiguring an existing system as needs for the system change over time. 
     SUMMARY OF THE INVENTION 
     The present invention provides a continuously installable/removable collector trolley. The trolley includes a chassis on its upper portion, having a plurality of electrically conductive brushes, which are spring biased upward. The upper portion of the chassis also includes a plurality of selectively extendable and retractable bearing assemblies. The lower portion of the trolley includes a means for extending and retracting the bearing assemblies, a means for connection to a power cord, and preferably one or more pulling loops. 
     In one preferred embodiment of the trolley, four bearing assemblies are provided, corresponding to the four corners of the trolley. The lower portion of the trolley preferably includes at least one release lever for extending and retracting the bearing assemblies. A preferred embodiment includes one release lever for each pair of bearing assemblies at each end of the trolley, although other possible embodiments may include a single release lever for extending and retracting all four bearings, or a separate release lever corresponding to each bearing assembly. A preferred embodiment of the release lever is a pivoting release lever, having a peg mounted radially outward from its pivot axis. The peg is dimensioned and configured to fit within a slot within the bearing assembly, so that pivoting of the release lever will cause the peg to move the bearing assembly inward or outward. For example, a pair of pegs mounted 180° apart may be utilized to enable one release lever to extend and retract a pair of bearing assemblies at one end of the trolley. 
     A typical bus section includes a housing with a plurality of conductor bars therein. An insulator may be provided between the conductor bars and the housing, with the bus bars retained within the insulator. The insulator is typically retained in the top of the housing. The bottom of the housing includes a shelf extending along each side, dimensioned and configured to permit the bearings to roll along it. The bottom surface of the insulator will typically be open, permitting the brushes to engage the bus bars. A polarizer extending from one side of the trolley, in conjunction with a polarizing lip depending downward from one side of the housing, may interfere with each other to resist insertion of the trolley into the conductor bar track in an incorrection orientation. 
     To install the trolley, a power cord for providing electrical power to a desired article of electric equipment may first be installed within the trolley. The release levers are manipulated to retract the bearings, and the trolley is inserted into the housing. The release levers are again manipulated to extend the bearings, securing the trolley within the housing. At this point, the bearings are free to roll along the shelves, and the bus bars are spring-biased upward to contact the conductor bars. Electrical current may thereby flow from the bus bars, through the brushes, to the power cord, and finally to the electrical equipment. Pulling chains may then be installed on the pulling loops to facilitate movement of the trolley within the system as desired. 
     A continuously installable/removable trolley for conductor bar systems is particularly useful for moving electrical equipment such as overhead cranes, aircraft hanger doors, and storage and retrieval systems. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric end view of a track section for a continuously installable/removable collector trolley according to the present invention. 
     FIG. 2 is an isometric top view of a continuously installable/removable collector trolley according to the present invention. 
     FIG. 3 is an isometric bottom view of a continuously installable/removable collector trolley according to the present invention. 
     FIG. 4 is a partially exploded isometric top view of a continuously installable/removable collector trolley according to the present invention. 
     FIG. 5 is a partially exploded isometric view of a combination of a continuously installable/removable collector trolley and an associated track section. 
     FIG. 6 is an end view of a continuously installable/removable collector trolley and its associated track, with the trolley having its bearings retracted. 
     FIG. 7 is an end view of a continuously installable/removable collector trolley and its associated track, with the trolley having its bearings extended. 
    
    
     Like reference numbers denote like elements throughout the drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the figures, the present invention provides a conductor bar system  10  having a plurality of track sections  12 , and a trolley  14  that may be installed or removed anywhere within any track section  12 . 
     Referring to FIG. 1, a preferred embodiment of a track section  12  is illustrated. The track section  12  includes an elongated housing  16 , having a top  18  and a pair of sides  20 ,  22  depending downward therefrom. A shelf  24 ,  25  is located along the bottom edge of each of the sides  20 ,  22 . The upper portion  26  of the track section  12  includes means for retaining an insulator  28 , with the illustrated means being a plurality of retention tabs  30 ,  32 . The top  16  also preferably includes a means for securing the track section  12  in a desired location, which in the illustrated embodiment includes the hanging flanges  34 ,  36 . One of the shelves  24 ,  25  (in the illustrated example, the shelf  24 ) may include a polarizing tab  38  depending downward therefrom. Although the illustrated embodiment of the track section  12  is made from metal, it may also be made from plastic, with the plastic being selected for its electrical insulating properties. 
     Although some embodiments of the track section  12  may include a housing  16  that also serves the purpose of providing electrical insulation, the illustrated embodiment includes a separate insulator  28  retained within the upper portion  26  of the housing  16 . The insulator  28 , when viewed from one end, has a cross section including a plurality of inverted U-shaped channels  40 , with each U-shaped channel  40  including a closed upper portion  42  and an open lower portion  44 . The ends of each U-shape are connected by insulator sections  46 . Insulator sections  48  extend outward from each side of the insulator  28 , preventing current from flowing into the housing  16  if the housing  16  is made from an electrically conductive material. The insulator  28  also defines a plurality of retention tab engaging surfaces  50 ,  52 , which, in cooperation with the retaining tabs  30 ,  32 , secure the insulator  28  in the upper portion  26  of the housing  16 . A conductor bar  54  is retained within the upper portion  42  of each inverted U-shaped channel  40 , being secured in this location due to the lower portion  44  having a narrower width than the upper portion  42 , preventing passage of the conductor  54  therethrough. Each of the conductor bars  54  therefore includes an exposed lower surface  56 . The shape of the insulator  28 , having the conductor bars  54  at the upper portion  42  of the inverted U-shaped channel  40 , with the lower portions  44  of the U-shaped channels being connected by insulator sections  46 , increases the distance that current would have to travel through the insulator  28  for a short to occur. Because air has a greater resistance than the insulator  28 , and because electrical resistance increases with increasing distance that current must travel through the material in question, electrical insulation between adjacent conductor bars  54  is maximized, while simultaneously enabling conductor bars  54  to be placed relatively close together. Although the illustrated embodiment shows conductor bars  54  only along the top of the housing  16 , alternative embodiments may also place conductor bars along the sides of the housing  16 . 
     Referring to FIGS. 2-4, a preferred embodiment of the trolley  14  is illustrated. The trolley  14  may be made from any suitably rigid material, with plastic being preferred. The trolley  14  includes a chassis  58  having four corners  60 . The chassis  58  includes a plurality of bearing assemblies  62 , with a preferred embodiment including one bearing assembly  62  corresponding to each corner  60 . Each bearing assembly  62  includes a body portion  64  and at least one bearing  66 , with the illustrated example including two bearings  66  rotatably secured to each body portion  64 . The body portion  64  is slidably mounted between the walls  68 ,  70 , each of which includes a guide rail  72  extending therefrom, and being dimensioned and configured to fit within a channel  74  defined on either side of the body  64 . Each body  64  further includes a pair of faces  76 ,  78 , with each face  76 ,  78  defining a slot  80 ,  82 , thereon. In the illustrated embodiment, each of the four bearing assemblies  62  is identical to the other bearing assemblies  62 , with two of the bearing assemblies  62  having the face  76  facing upward, and the remaining two bearing assemblies  62  having the face  78  facing upward. 
     The chassis  58  further includes operating handles  84  for extending and retracting the bearing assemblies  62 . The illustrated embodiment includes a single operating handle corresponding to the pair of bearing assemblies  62  at each end  86 ,  88  of the chassis  58 . Each operating handle  84  includes a base  90  having a pivot  92  extending upward therefrom. In the illustrated embodiment, the pivot  92  is dimensioned and configured to fit within the aperture  94  defined within the chassis  58 , where it is secured by the screw  96 , fitting within the screw aperture  98  defined within the pivot  92 . At least one peg  100  extends upward from the base  90 , and is located radially outward from the pivot  92 . The illustrated embodiment includes a pair of pegs  100  extending from each base  90 , with the pegs being substantially 180° apart. Each of the pegs  100  is dimensioned and configured to fit within the slots  80 ,  82  of the bearing assemblies  62 . Rotation of the operating handle  84  would therefore cause the pegs  100  to push against and slide within the slots  80 ,  82 , causing the bearing assembly  62  to slide between the walls  68 ,  70 . The operating handle  84  further includes a grasping portion  102 , and a means for retaining the operating handle  84  in a position corresponding to the extended position of the bearing assemblies  62 . In the illustrated example, the hook  104 , extending outward from the grasping portion  102 , engages a slot  106  defined within the lower portion  108  of the chassis  58  when the operating handle  84  is in a position corresponding to the extended position of the bearing assembly. 
     The upper portion  110  of the chassis  58  also includes a plurality of brushes  112 , with each brush  112  corresponding to one conductor bar  54 . The brushes  112  in the illustrated embodiment are substantially rectangular, and are slidably mounted within a channel  114  defined in the upper portion  110  of the chassis  58 , so that they may move between a retracted position and an extended position. The brushes  112  are retained in the channel  114  by a brush retaining plate  116  having a tab  118  extending therefrom. The tab  118  is dimensioned and configured to fit within a slot  120  defined within the brush  112 . Each of the brushes  112  is spring-biased towards its extended position by at least one spring  122 , bearing against the lower surface  124  of the brush  112 . The illustrated example includes a pair of springs  122  corresponding to each brush  112 . Although not shown, it is well understood by those skilled in the art that each of the brushes  112  would have at least one electrically conductive wire extending therefrom, through the channel  126  defined within the lower portion  108  of the chassis  58 , and extending to a desired article of electrical equipment. Although the illustrated brushes  112  all extend upward from the chassis  58  to engage conductor bars  54  located adjacent to the top  18  of the track section  12 , other embodiments may include brushes extending horizontally from the chassis  58  to engage bus bars located along the sides  20 ,  22  of the track section  12 . 
     A pulling chain (not shown but well known in the art) may be secured to a pulling loop  128 , and connected at its other end to the electrical equipment, so that the trolley  14  may move within the conductor bar system  12  to remain in close proximity with the electrical equipment. 
     After installing a conductor bar system comprising a plurality of track sections  12 , one or more trolleys  14  may be used within this system to supply power to a moving piece of electrical equipment. The trolley would first be connected to the equipment for which it will supply power. As shown in FIG. 5, the trolley  14  may be inserted between the shelves  24 ,  25  of the track section  12  when the operating handles  84  are rotated to retract the bearing assemblies  62 . The polarizer  130  extending from one side of the chassis  58  would interfere with the polarizing tab  38  if the trolley  14  were inserted into the track section  12  in the incorrect orientation. FIG. 6 illustrates the trolley  14  inserted into the track section  12  in the correct orientation, with the polarizer  130  and polarizing tab  38  on opposite sides. In this position, the brushes  112  are in contact with, and forming an electrical connection with, the conductor bars  54 . Once the trolley  14  is inserted into the track section  12 , the operating handles  84  may be rotated to extend the bearing assemblies  62 , so that the bearings  66  rest on the shelves  24 ,  25 , thereby securing the trolley  12  within the conductor bar system  10 . If desired, a pulling chain may be secured between one or more of the pulling loops  128  and the electrical equipment. Any time it is desired to remove the trolley  14  from the conductor bar system  12 , rotation of the operating handles  84  will retract the bearing assemblies  62  from the position of FIG. 7 to the position of FIG. 6, permitting removal of the trolley  14  from any track section  12 . 
     While a specific embodiment of the invention has been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.