Abstract:
A lobed bushing is provided for a track assembly of a track-type machine. The track assembly includes a first chain and a second chain coupled together with a track pin. A bushing, defining a longitudinal axis, includes a central bore oriented along the longitudinal axis and extending from a first end of the bushing to a second end of the bushing for receiving the track pin. The bushing includes a first lobe positioned at a first location about the longitudinal axis and a second lobe positioned at a second location about the longitudinal axis that is less than about 180° from the first location. The first end of the bushing has a substantially cylindrical shape.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application is a continuation-in-part of U.S. patent application Ser. No. 12/151,948, filed May 9, 2008. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates generally to a material handling system for a manufacturing line, and more particularly to a modular material handling system including a dual track assembly. 
       BACKGROUND 
       [0003]    During a manufacturing process, a product is typically advanced through a plurality of manufacturing stations of a manufacturing chain. Specifically, the product is transported through each of the manufacturing stations along an article transportation device. At each manufacturing station, a specific one of a plurality of tasks in the manufacturing process is performed. All equipment and other components necessary to perform the assigned task are positioned, and often permanently affixed, at each manufacturing station. As a result, and dependent upon the number of tasks and the complexity of the manufacturing process, a manufacturing chain is typically a large structure that is permanently situated inside a manufacturing facility. 
         [0004]    At least partially as a result of its permanency, a manufacturing chain is typically inflexible, such that modifying, removing, or replacing the manufacturing chain may be an expensive and time-consuming process. Therefore, even minor improvements to the manufacturing process, such as, for example, changes to the equipment positioned at one manufacturing station, may be too expensive and time consuming to implement. Further, if the manufacturing process performed by the manufacturing chain becomes unnecessary, it may not be feasible to alter the manufacturing chain to perform a different manufacturing process. Ultimately, the manufacturing chain may only be cost effective in performing the specific manufacturing process for which it was designed. As a result, the significant amount of costs and efforts to design and construct the manufacturing chain may be wasted. 
         [0005]    Another drawback with conventional manufacturing chains involves the article transportation system along which the products are transported. Since the products are typically carried along one article transportation device having a single driving source, such as a common monorail conveyor, the entire manufacturing chain must be stopped in order to correct a problem occurring at any point along the manufacturing chain. Power and free conveyors offer one solution by allowing carriers to be routed off of the main line, such as if a defect is identified, but still provide continuous movement of the main line. In either case, stopping the main line can result in significant down time and, therefore, reduced efficiency and, ultimately, throughput of the manufacturing chain. This may further increase process time for manufacturing processes that already require a significant amount of time. For example, it is known that a drying or curing stage of a paint process may require a significant amount of time, thus greatly increasing the minimal process time for the manufacturing process. 
         [0006]    U.S. Pat. No. 6,120,604 teaches a powder coating chain having a plurality of conveyors for transporting parts through a plurality of processing areas. Specifically, each processing area includes a separate motor driven conveyor, sensors for providing information on conditions within the processing area, and a control circuit coupled to both the sensors and an operator interface. A user may manipulate the operator interface to monitor sensed conditions within each processing area. Although the reference suggests an aspect of modularity that may offer certain limited benefits, it does not contemplate improvements to the overall process flow within the manufacturing chain. In fact, the reference does not disclose modifications to the exemplary high-speed blank powder coating process, but rather seeks to quickly identify a source of a mechanical problem associated with the process. As should be appreciated, there is a continuing need for manufacturing chains providing improved quality and efficiency with respect to a manufacturing process. In addition, there is a continuing need for manufacturing chains, or manufacturing stations thereof, that may be more easily modified, removed, or replaced. 
         [0007]    The present disclosure is directed to one or more of the problems set forth above. 
       SUMMARY OF THE DISCLOSURE 
       [0008]    In one aspect, a material handling system includes a first track assembly configured to transport a forward trolley along a first path. The material handling system also includes a second track assembly configured to transport a trailing trolley along a second path. The second path is substantially parallel to the first path. A carrier is configured to support an article and has a first end pivotably supported by the forward trolley and a second end pivotably supported by the trailing trolley. 
         [0009]    In another aspect, a method of operating a material handling system includes transporting an article along the material handling system, at least in part, by supporting the article on a carrier. The carrier has a first end pivotably supported by a forward trolley and a second end pivotably supported by a trailing trolley. The forward trolley is moved along a first track assembly defining a first path, while the trailing trolley is moved along a second track assembly defining a second path. The first path and the second path are parallel. 
         [0010]    In yet another aspect, a manufacturing line includes a plurality of manufacturing modules positioned in series and defining at least one main path through the manufacturing line. Each manufacturing module including a material handling system for transporting an article along the main path. The material handling system of at least one manufacturing module includes a first track assembly configured to transport a forward trolley along a first path and a second track assembly configured to transport a trailing trolley along a second path. The second path is parallel to the first path. A carrier is configured to support the article and has a first end pivotably supported by the forward trolley and a second end pivotably supported by the trailing trolley. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a diagrammatic perspective view of a manufacturing chain, according to the present disclosure; 
           [0012]      FIG. 2  is a diagrammatic perspective view of a manufacturing module of the manufacturing chain of  FIG. 1 , according to the present disclosure; 
           [0013]      FIG. 3  is a side diagrammatic view of an alternative embodiment of the manufacturing module of  FIG. 2 , according to the present disclosure; 
           [0014]      FIG. 4  is a side diagrammatic view of an alternative embodiment of the manufacturing module of  FIG. 2  including a first vertical lift device, according to the present disclosure; 
           [0015]      FIG. 5  is a side diagrammatic view of an alternative embodiment of the manufacturing module of  FIG. 2  including a second vertical lift device, according to the present disclosure; 
           [0016]      FIG. 6  is a block diagram of one embodiment of a control system for operating the manufacturing chain of  FIG. 1 , according to the present disclosure; 
           [0017]      FIG. 7  is a block diagram of an alternative embodiment of a control system for operating the manufacturing chain of  FIG. 1 , according to the present disclosure; and 
           [0018]      FIG. 8  is a perspective view of one embodiment of a modular material handling system, according to the present disclosure; 
           [0019]      FIG. 9   a  is a cross-sectional view of a first exemplary composite beam for use with the modular material handling system of  FIG. 8 , according to the present disclosure; 
           [0020]      FIG. 9   b  is a cross-sectional view of a second exemplary composite beam for use with the modular material handling system of  FIG. 8 , according to the present disclosure; 
           [0021]      FIG. 9   c  is a cross-sectional view of a third exemplary composite beam for use with the modular material handling system of  FIG. 8 , according to the present disclosure; 
           [0022]      FIG. 10  is a partially exploded view of a manufacturing module including the modular material handling system of  FIG. 8 , according to the present disclosure; 
           [0023]      FIG. 11   a  is plan view of a modular material handling system including a dual track assembly, according to the present disclosure; 
           [0024]      FIG. 11   b  is a side diagrammatic view of a trolley assembly configured to support a carrier along the dual track assembly of  FIG. 11   a,  according to the present disclosure; 
           [0025]      FIG. 12  is a side diagrammatic view of a buffer, according to the present disclosure; 
           [0026]      FIG. 13  is a block diagram of a first line, according to the present disclosure; and 
           [0027]      FIG. 14  is a plan view of a second line, according to the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    An exemplary embodiment of a manufacturing chain  10  is shown generally in  FIG. 1 . The manufacturing chain  10  may be disposed within a manufacturing area  12 , such as, for example, a manufacturing area defined by a building  14 . According to one embodiment, the manufacturing chain  10  may be secured to, and positioned above, a planar floor  16  of the manufacturing area  12 . However, numerous locations and arrangements are contemplated for the manufacturing chain  10 . According to the exemplary embodiment, the manufacturing chain  10  may be used to perform a paint process, such as, for example, a powder coating process, and, therefore, may also be referred to as a paint line. Although a paint process is described, however, it should be appreciated that the manufacturing chain  10  may be designed to perform any of a variety of manufacturing processes. 
         [0029]    The manufacturing chain  10 , also referred to as a modular manufacturing chain, may include several modular manufacturing stations, such that each modular manufacturing station is configured to perform at least one task in the manufacturing process. Specifically, and according to one example, the manufacturing chain  10  may include a wash station  18 , a blow off station  20 , an inspection station  22 , a paint application station  24 , a curing station  26 , and an unload station  28 . Although six modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28  are shown, it should be appreciated that the manufacturing chain  10  may include any number of modular manufacturing stations necessary to perform the designated manufacturing process. It should also be appreciated that the paint process, as described herein, has been simplified for ease of explanation, and is in no way meant to be limited to the specific tasks described. 
         [0030]    The modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28  may be positioned in series, as shown, or the manufacturing chain  10  may include one or more of the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28  positioned in parallel, as dictated by the specific tasks of the manufacturing process. Further, the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28  may include equipment, and other components, necessary to accomplish the task to be performed at the respective one of the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 . It should be appreciated that multiple tasks may be performed at one modular manufacturing station or, alternatively, a more complex task may be performed over a plurality of modular manufacturing stations. Ultimately, one or more tasks may be performed on an article, or product, as it is transported through the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28  along an article transportation system  30 , described later in greater detail. 
         [0031]    The equipment and other components necessary to perform a task at a respective one of each of the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28  may be supported by a framework or, more specifically, a manufacturing module  32 . For example, the manufacturing chain  10  may include a plurality of manufacturing modules  32  positioned and configured to accommodate the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 . As shown in the embodiment of  FIG. 1 , the manufacturing modules  32  may be positioned in series, as dictated by the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 . However, the size and geometry of the manufacturing chain  10 , comprising the manufacturing modules  32 , may include any of a variety of possible sizes and configurations, such as, for example, an “L” shaped configuration or a “U” shaped configuration. Further, although  FIG. 1  illustrates exactly one of the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28  associated with each manufacturing module  32 , it should be appreciated that each manufacturing module  32  may support more than one of the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 . 
         [0032]    According to the exemplary embodiment, the wash station  18  may be configured to perform a wash and/or rinse task of the paint process. Specifically, the wash station  18  may include a water tank  34 , supported by the manufacturing module  32 , for supplying water, or a solvent mixture, to the wash station  18 . Alternatively, however, water may be supplied directly to the wash station  18  from a utility infrastructure of the building  14  or, alternatively, from an external utility connection  36  disposed outside the manufacturing area  12  and connected to the manufacturing chain  10  via a conduit  38 . The external utility connection  36  may, therefore, include a source of water or, alternatively, may include a source of another utility, such as, for example, electric power or data. 
         [0033]    According to the current embodiment, the conduit  38  may provide water to a utility transfer module  40  supported by the manufacturing module  32 . The utility transfer module  40  may be configured to transfer a utility, such as, for example, electric power, fluid, or data, through the manufacturing module  32 . The utility may be used at the wash station  18  and, further, may be transferred to a contiguous manufacturing module  32 . For example, each of the other manufacturing modules  32  may include utility transfer modules  40 , such that a utility may be supplied at one manufacturing module  32  and used at another. Specifically, each manufacturing module  32  may receive a utility from a preceding manufacturing module  32  of the manufacturing chain  10 , and may transfer the utility to a succeeding manufacturing module  32 . 
         [0034]    The wash station  18  may further include a water pump  42  for circulating the water or solvent mixture through the wash station  18  and/or pressurizing the water or solvent mixture. According to one embodiment, the water or solvent mixture may be directed through a plurality of water nozzles  44 , such that the water nozzles  44  are configured to spray an article as it passes through the wash station  18  to remove any foreign substances deposited on the article. Such foreign substances may include, for example, grease, dirt, dust, oils, or any other substances that may interfere with the paint application process. The wash station  18  may also include a plurality of water barrier panels  46  for preventing the water or the solvent mixture from escaping the wash station  18 , and a drain system for returning the used water or the solvent mixture to the water tank  34 . It should be appreciated that the wash station  18  may include any equipment useful in removing foreign substances from an article before paint, such as, for example, powdered paint, is applied. 
         [0035]    The blow off station  20  may be configured to remove any water or solvent mixture remaining on the article after the article passes through the wash station  18 . Specifically, the blow off station  20  may include a fan  48 , or pump, for pressurizing air and a plurality of air nozzles  50  for directing the pressurized air toward the article. Either or both of the fan  48  and air nozzles  50  may be supported by the manufacturing module  32 . Further, the blow off station  20  may include a hose (not shown) available to an operator for manually directing pressurized air toward the article. According to one embodiment, pressurized air may be provided via the utility transfer module  40 . Specifically, pressurized air may be supplied to the utility transfer module  40  directly from a source, or indirectly via the utility transfer module  40  of a contiguous manufacturing module  32 . 
         [0036]    Air barrier panels  52 , or walls, may also be provided at the blow off station  20  for preventing pressurized air blown from the air nozzles  50  from interfering with activities or equipment outside of the blow off station  20 . After the water or solvent mixture is sufficiently removed from the article at the blow off station  20 , the article may be transported to the inspection station  22 , which may provide a location for an operator  54  to inspect the article. The inspection may, for example, involve visual, physical, or chemical analyses to determine the presence of any remaining impurities on the surface of the article. 
         [0037]    After inspection, the article may be transported along the article transportation system  30  to the paint application station  24 . The paint application station  24  may include a piece of paint application equipment  56  for coating the article with paint, such as, according to one example, a powdered paint. The paint application station  24  may further include a plurality of paint barrier panels  58  for restricting the paint to the confines of the paint application station  24 . Either or both of the paint application equipment  56  and the paint barrier panels  58  may be supported by the manufacturing module  32 . Alternatively, however, the paint application equipment  56  and the paint barrier panels  58  may be secured to the planar floor  16 . As should be appreciated, the equipment used at the paint application station  24  may vary, depending on the type of paint used and the application process that is implemented. For example, the paint may be sprayed onto the article or, alternatively, the article may be immersed in a tank containing paint. 
         [0038]    From the paint application station  24 , the article may be transported to the curing station  26 . The curing station  26  may be configured to heat or otherwise cure the coating of freshly applied paint. According to one embodiment, the curing station  26  may include a plurality of infrared heaters  60 , which may contain a plurality of infrared heater lamps  62  for generating the heat necessary for causing the coating of paint on the article to cure. According to one embodiment, the infrared heaters  60  may be portable. For example, one or more sets of rollers  64  may be provided to facilitate movement of the infrared heaters  60  from one location, such as a storage location, and into the illustrated position relative to the paint application station  24 . It should be appreciated that “portable” equipment, as used herein, may refer to any equipment or component that may not be characterized as a fixture or otherwise permanently attached component. It should also be appreciated that any equipment useful in making the coating of paint applied to the article permanent is contemplated for use at the curing station  26 . 
         [0039]    For simplicity, the exemplary paint process is described as having one paint application station  24 ; however, it should be appreciated that a paint process may often include coating the article with multiple coatings of paint. As a result, the manufacturing chain  10  may include additional paint applications stations  24  and, if necessary, manufacturing modules  32  to accommodate such a process. Ultimately, after the desired number of paint coatings are applied to the article, the article may be transported to the unload station  28 . At the unload station  28 , the article may be removed from the manufacturing chain  10  or, more specifically, the article transportation system  30  by an operator  66 . After passing through the manufacturing chain  10 , it is contemplated that the article may be transported to another manufacturing chain for further processing, if desired. According to one embodiment, the article may be routed to a buffer area before passing to another manufacturing chain. Alternatively, the article may be taken to a storage location for storage, or to a transportation vehicle for delivery to a customer. 
         [0040]    Turning now to  FIG. 2 , an exemplary manufacturing module  32  for supporting one or more of the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28  of  FIG. 1  is shown in greater detail. Specifically, the manufacturing module  32  may consist of a plurality of beams, such as tubular beams, forming a framework or skeleton  80 . According to one embodiment, the skeleton  80  may include a plurality of vertically aligned support beams  82 ,  84 ,  86 , and  88  attached to the planar floor  16  using support plates  90 ,  92 ,  94 , and  96 , respectively. Although a bolted connection is shown, it should be appreciated that the support beams  82 ,  84 ,  86 , and  88  and/or support plates  90 ,  92 ,  94 , and  96  may be attached to the planar floor  16  using any secure connection. 
         [0041]    The vertically aligned support beams  82 ,  84 ,  86 , and  88  may be interconnected using a plurality of additional support beams, such as horizontally aligned beams  98 ,  100 ,  102 , and  104 . The horizontally aligned support beams  98 ,  100 ,  102 , and  104  and vertically aligned support beams  82 ,  84 ,  86 , and  88  may define an entry  106  and an exit  108  of the manufacturing module  32 , and may provide structural support for one or more modular manufacturing stations, such as the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28  of  FIG. 1 . As such, the support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104  may be fabricated from steel, carbon composites, or any other material known in the art suitable for providing the desired support. According to one embodiment, it may be desirable to utilize a relatively lightweight material to ease the transport and/or construction of the manufacturing module  32 . 
         [0042]    Additionally, it may be desirable to allow for expansion and/or contraction of one or more of the support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104 . Such expansion and/or contraction may further ease the transport and/or construction of the manufacturing module  32 , and may also allow for a customized size and/or shape of each manufacturing module  32 . For example, the desired size and/or shape of the manufacturing module  32  may depend upon a number of factors including, but not limited to, the number of modular manufacturing stations, such as modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 , disposed within the manufacturing module  32 . 
         [0043]    To facilitate adjustment, one or more of the support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104  may include a hollow tubular portion and a piston portion. For example, vertically aligned support beam  82  is shown having a tubular portion  82   a  and a piston portion  82   b.  As should be appreciated, the piston portion  82   b  may be slidably received within the tubular portion  82   a  and locked at a desired length. Locking may be accomplished using any known fastening devices, such as, for example, bolts, screw, pins, or spring-actuated bearings. Alternatively, however, each of the support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104  may be fabricated to various desired lengths, as dictated by the design of the manufacturing module  32 . According to one embodiment, it may be desirable to expand and/or contract only the vertically aligned support beams  82 ,  84 ,  86 , and  88 . 
         [0044]    Although the support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104  are illustrated as forming a cubic shape, they may, alternatively, be positioned to form any shape conducive to the specific manufacturing process being performed. Additionally, the number of support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104  utilized to form the skeleton  80  may vary depending upon the shape of the manufacturing module  32 . The support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104  of the manufacturing module  32  may be secured together by mechanical fasteners, welds, or any other devices known in the art that are used to secure components. Additionally, the skeleton  80  of the manufacturing module  32  may be attached to the framework of a contiguous manufacturing module  32  using similar fasteners. Alternatively, however, the manufacturing module  32  may be positioned adjacent a contiguous manufacturing module  32  and may not be attached thereto. A “contiguous” manufacturing module, as used herein, may refer to a manufacturing module, such as manufacturing module  32 , positioned in close proximity to another manufacturing module, such as, for example, a preceding or succeeding manufacturing module in the manufacturing chain  10 . 
         [0045]    One or more of the support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104  of the skeleton  80  may support the utility transfer module  40 . The utility transfer module  40  may be configured to transfer at least one of electric power, fluid, and data through the manufacturing module  32 . Specifically, the utility transfer module  40  may transfer and/or provide electric power, water, compressed air, gas, or other utilities to the one or more modular manufacturing stations, such as modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 , supported by the manufacturing module  32 . According to one embodiment the utility transfer module  40  may include a collection of wires, cables, or other conduits capable of transferring one or more utilities. 
         [0046]    The utility transfer module  40  may include an external port  110  for engaging an external utility connection, such as, for example, the external utility connection  36  of  FIG. 1 . Although the external utility connection  36  is positioned outside the building  14 , it should be appreciated that the external utility connection  36  may be positioned within the building  14 , such as within the manufacturing area  12 . According to one embodiment, the external utility connection  36  includes a utility source, such as, for example, an electric power grid, a generator, a battery, a compressed air tank, a hydraulic tank, and/or a water supply. It should be appreciated that the external utility connection  36  may include any source of a utility that is utilized by the manufacturing chain  10 . Accordingly, each utility transfer module  40  may include multiple external ports  110 , depending on the number of utility sources to be engaged. 
         [0047]    Each utility transfer module  40  may also include an entry port  112  for engaging a utility transfer module  40  of a preceding manufacturing module  32 , and an exit port  114  for engaging a utility transfer module  40  of a succeeding manufacturing module  32 . It should be appreciated that the entry port  112  of the utility transfer module  40  of the first manufacturing module  32  in the manufacturing chain  10  may remain unused and, similarly, the exit port  114  of utility transfer module  40  of the last manufacturing module  32  may remain unused. Such ports, however, may become necessary, such as, for example, when an additional manufacturing module  32  is added to the manufacturing chain  10 . 
         [0048]    Additionally, the utility transfer module  40  may include one or more equipment ports, such as a first equipment port  116 , for providing a utility to the one or more modular manufacturing stations, such as the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 , of the manufacturing module  32 . According to a more general example, manufacturing module  32  may support a first modular manufacturing station  118  that is configured to perform at least one task of a manufacturing process. Accordingly, the first modular manufacturing station  118  may include equipment, and other systems and/or components, necessary to accomplish the task to be performed. Specifically, and according to one example, the first modular manufacturing station  118  may include a piece of manufacturing equipment  120 , an article transportation device  122  representing a portion of the article transportation system  30  corresponding to the station  118 , and a station control system  124 . Although the manufacturing equipment  120  is exemplified as a plurality of air nozzles, similar to air nozzles  50 , it should be appreciated that any manufacturing equipment useful in performing a manufacturing task is contemplated. 
         [0049]    One or more of the manufacturing equipment  120 , the article transportation device  122 , and the station control system  124  may receive utilities, such as electric power, fluid, and data, from the utility transfer module  40 . For example, the manufacturing equipment  120  may include a conduit  126  having a quick connect coupling member  128  for engaging the first equipment port  116 . Similarly, the article transportation device  122  may include a conduit  130  having a quick connect coupling member  132  for engaging a second equipment port  134  of the utility transfer module  40 . In addition, the station control system  124  may include conduit  136  having a quick connect coupling member  138  for engaging a third equipment port  140  of the utility transfer module  40 . 
         [0050]    It should be appreciated that any of the ports or connections described herein, such as, for example, ports  110 ,  112 ,  114 ,  116 ,  134 , and  140 , may embody electrical outlets, quick connect coupling members, or any other known utility interfaces. In addition, each of the quick connect coupling members  128 ,  132 , and  138  may embody any appropriate utility interface for engaging one or more of the ports  110 ,  112 ,  114 ,  116 ,  134 , and  140 . It should also be appreciated that quick connect coupling members may enable relatively quick and easy assembly and/or disassembly of the manufacturing stations, such as modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 , and/or first modular manufacturing station  118 . Additional benefits may be recognized by utilizing common, or universal, interfaces throughout the entire manufacturing chain  10 . 
         [0051]    According to one embodiment, the utility transfer module  40  may be secured to one of the support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104 , such as support beam  102 , using one or more mounting devices  142 . Mounting devices  142  may, for example, include hooks, latches, sockets, or any other devices capable of securing the utility transfer module  40  to one or more of the support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104 . Alternatively, however, the utility transfer module  40  may be positioned within a hollow portion, such as, for example, a central portion, of one or more of the tubular support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104 . It should be appreciated that the utility transfer module  40  may be supported by and/or secured to any number of the support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104 , as necessary to transfer a utility through and/or provide a utility to the manufacturing module  32 . 
         [0052]    Turning now to  FIG. 3 , an alternative embodiment of a manufacturing module  32  is shown. Specifically, one or more of the manufacturing modules  32  may include a second modular manufacturing station  160  disposed between the entry  106  and the exit  108  of the manufacturing module  32 . The second modular manufacturing station  160  may include similar systems and/or components as the first modular manufacturing station  118 . Specifically, the second modular manufacturing station  160  may include at least one piece of manufacturing equipment  120 , an article transportation device  122  representing a portion of article transportation system  30  corresponding to the second modular manufacturing station  160 , and a station control system  124 . 
         [0053]    It should be appreciated that each of the systems and/or components of the second modular manufacturing station  160  may also receive a utility from the utility transfer module  40  in a manner similar to that described above. It should further be appreciated that either or both of the first and second modular manufacturing stations  118  and  160  may be representative of the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28  of  FIG. 1 . Accordingly, each of the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28  may generally include one or more of the manufacturing equipment  120 , article transportation device  122 , and station control system  124 . 
         [0054]    Each article transportation device  122  may include a friction drive system having one or more sets of carrier tracks, such as carrier tracks  162 , along which a carrier  164  may be transported. It should be appreciated that the one or more sets of carrier tracks  162  may define a transportation path  166  through a manufacturing chain, such as the manufacturing chain  10  of  FIG. 1 . Friction drive systems are known, and may generally include one or more hanger rails  168  fixedly attached to the skeleton  80  for supporting one or more support rails  170 . At least one of the support rails  170  may provide support for a drive shaft  172  that may be mechanically coupled to a drive system  174 . 
         [0055]    The drive system  174  may, for example, include an electric, hydraulic, or pneumatic motor, and may further include a transmission and controls, as necessary, for driving the drive shaft  172  at a desired speed and in a desired direction. For example, the drive shaft  172  may be rotated in a first direction for frictionally engaging wheels of the carrier  164  such that the carrier  164  is moved in a forward transport direction, represented by arrow “F”. Alternatively, however, the drive shaft  172  may be rotated, by the drive system  174 , in an opposite direction for frictionally engaging wheels of the carrier  164  to move the carrier  164  in a reverse transport direction “R” that is opposite the forward transport direction “F.” A similar friction drive system may be provided by OCS IntelliTrak, Incorporated of Cincinnati, Ohio. 
         [0056]    Although a friction drive system is described, however, it should be appreciated that a variety of material handling systems may be used. For example, an air balancer, a series of hoists, an electrified monorail, or any other device capable of moving an article through the manufacturing chain  10  are also contemplated. Further, it should be appreciated that carriers, such as carriers  164 , may include any devices capable of gripping an article to be conveyed through the manufacturing chain  10 . Exemplary carriers may, for example, include hooks, clamps, latches, or any other devices capable of temporarily grasping the article. Although a single carrier  164  is depicted for transporting an article, it should be appreciated that multiple carriers may be necessary for transporting the article, depending on the size and weight of the article. 
         [0057]    It is also contemplated that the article transportation system  30  may be substituted with a chain, belt, or any other device that may convey carriers  164  through the manufacturing chain  10 . According to one embodiment, the article transportation system  30  may be mounted to the planar floor  16  and/or contain a transport device, such as, for example, a conveyor belt to convey the article through the manufacturing chain  10 . Preferably, however, the article transportation devices  122  that define the article transportation system  30  may each include at least one drive system  174 , or similar means, for facilitating independent movement of the carrier  164  within the respective one of the manufacturing stations  118  and  160 . 
         [0058]    Each station control system  124  may be configured to control operation of at least one of the article transportation device  122  and the manufacturing equipment  120  of the respective one of the modular manufacturing stations  118  and  160 . Specifically, the station control system  124  may be in communication with the article transportation device  122  or, more specifically, the drive system  174 , and may be configured to issue an operation signal, such as, for example, a forward signal, a reverse signal, and a stop signal. The forward signal may correspond to the forward transport direction “F,” the reverse signal may correspond to the reverse transport direction “R,” and the stop signal may correspond to a stationary position. It should be appreciated that the stationary position may represent a state in which the carrier  164  is not driven in either of the forward transport direction “F” or the reverse transport direction “R”. 
         [0059]    According to one embodiment, the carrier  164  of the first modular manufacturing station  118  may be driven in the forward transport direction “F” while the carrier  164  of the second modular manufacturing station  160  is simultaneously driven in the reverse transport direction “R” or, alternatively, remains stationary. According to a specific example, it may be desirable to move the carrier  164  of the second modular manufacturing station  160  in the reverse transport direction “R” relative to the manufacturing equipment  120 . As should be appreciated, continuous forward and reverse movement relative to the manufacturing equipment  120  may prove beneficial in a variety of tasks of a manufacturing process, including, but not limited to, a wash task and a blow off task, as described above. According to an additional example, it may be desirable to stop the carrier  164  of the second modular manufacturing station  160 , such as in response to the identification of a defect, while one or more other carriers  164  continue to move. A variety of defects are contemplated, such as, for example, defects resulting from process problems and/or equipment failures. 
         [0060]    Each modular manufacturing station  118  and  160  may also include one or more position tracking devices. According to one embodiment, a first position tracking device  176 , a second position tracking device  178 , and a third position tracking device  180  are each positioned for detecting a position of the carrier  164  as it is transported through the station  118  and  160 . Position tracking devices  176 ,  178 , and  180  are known, and may include, for example, position sensors, proximity switches, bar code readers, or any other devices capable of detecting a position of the carrier  164 . In addition, the position tracking devices  176 ,  178 , and  180  may be supported by the skeleton  80 , the article transportation device  122 , or may be otherwise positioned. Although three position tracking devices  176 ,  178 , and  180  are shown, it should be appreciated that any number of position tracking devices may be used, as dictated by the manufacturing process. 
         [0061]    Each station control system  124  may also be in communication with the position tracking devices  176 ,  178 , and  180 , and may receive signals from one or more of the position tracking devices  176 ,  178 , and  180  that are indicative of first, second, and third detected positions of the carrier  164 . Each station control system  124  may also be configured to issue one or more operation signals, such as, for example, the forward signal, reverse signal, and stop signal, to the article transportation device  122  based, at least in part, on one of the detected carrier positions. According to one example, it may be desirable for the station control system  124  to issue the stop signal to the article transportation device  122  when the carrier  164  has reached a predetermined position relative to the manufacturing equipment  120 . After a predetermined period of time, for example, the station control system  124  may then issue the forward signal to the article transportation device  122 . Further, the station control system  124  may issue one or more operation signals to the manufacturing equipment  120  based, at least in part, on one of the detected carrier positions. 
         [0062]    Turning now to  FIG. 4 , an alternative embodiment of a manufacturing module  32  is shown. Specifically, the transportation path  166  defined by the carrier tracks  162  may include a vertical discontinuity  200 . It should be appreciated that, according to one example, the vertical discontinuity  200  may occur where the transportation path  166  includes a first transport height  202  that is vertically spaced from a second transport height  204 . Specifically, the two sets of carrier tracks  162  of the first modular manufacturing station  118  may be positioned at the first transport height  202 , while the carrier tracks  162  of the second modular manufacturing station  160  are positioned at the second transport height  204 . Such a discontinuity along the transportation path  166  may occur as a result of the design of the manufacturing chain  10 , as dictated by a topography of the manufacturing area  12  or a variety of other factors. Additionally, it may be desirable to alter the height of the transportation path  166  relative to the manufacturing equipment  120 . 
         [0063]    A first vertical lift device  206  may be provided for moving one of the sets of carrier tracks  162  in a vertical direction relative to the transportation path  166 . Specifically, the first vertical lift device  206  may be configured to move one of the sets of carrier tracks  162 , adjacent the vertical discontinuity  200 , from the first transport height  202  to the second transport height  204 . Vertical lift devices, such as vertical lift device  206 , are known, and may include, for example, electric or pneumatic lifts, and, as such, may receive any necessary utilities from the utility transfer module  40 . In addition, the first vertical lift device  206  may be supported by and/or secured to the skeleton  80  of the manufacturing module  32 . 
         [0064]    A control system, such as, for example, the station control system  124 , may also be provided for controlling operation of the first vertical lift device  206 . Specifically, and according to one embodiment, the station control system  124  may also be in communication with the first vertical lift device  206 , and may be configured to issue operation signals thereto, such as, for example, a raise signal and a lower signal. For example, the first vertical lift device  206  may be configured to move the carrier tracks  162  from the first transport height  202  to the second transport height  204  in response to the raise signal. In addition, the first vertical lift device  206  may be configured to move the carrier tracks  162  from the second transport height  204  to the first transport height  202  in response to the lower signal. 
         [0065]    Further, the station control system  124  may be configured to issue the raise signal and/or the lower signal in response to a carrier position that is detected by one of the position tracking devices  176 ,  178 , and  180 . Specifically, and according to one example, it may be desirable to issue the raise signal when it is determined that the carrier  164  has reached a predetermined position relative to the carrier tracks  162 . After the carrier tracks  162  have been raised, the carrier  164  may continue to be transported along the transportation path  168  at the second transport height  204 , such as by the drive system  174 . 
         [0066]    The transportation path  168  may include additional vertical discontinuities, such as, for example, a second vertical discontinuity  210 , shown in  FIG. 5 . A second vertical lift device  212 , similar to first vertical lift device  206 , may, therefore, be provided to advance the carrier  164  through the second vertical discontinuity  210 . Specifically, the second vertical lift device  212  may move the carrier tracks  162  from the second transport height  204  to the first transport height  202 , such as in response to the lower signal issued from the station control system  124 . It should be appreciated that the station control system  124  may issue the lower signal in response to a carrier position detected by one of the position tracking devices  176 ,  178 , and  180 . It should also be appreciated that any number of vertical lift devices, such as lift devices  206  and  212  that may be manually or automatically operated, may be used throughout the manufacturing chain  10  to accommodate vertical discontinuities and/or to move one of the carriers  164  in a vertical direction relative to the manufacturing equipment  120 . 
         [0067]    According to one embodiment, it may be desirable to incorporate one or more vertical lift devices, such as the lift devices  206  and  212 , into the manufacturing chain  10  to accommodate manufacturing equipment  120  positioned above the planar floor  16 . Specifically, the manufacturing chain  10  may include one or more pieces of manufacturing equipment  120  that traditionally were positioned below the planar floor  16 , such as, for example, tanks or baths. For ease of deployment, the manufacturing chain  10  may position all equipment  120 , including such tanks or baths, above ground and, therefore, may advance the carriers  164  through the manufacturing chain  10  and relative to the manufacturing equipment  120  using one or more vertical lift devices  206  and  212 . 
         [0068]    It should be appreciated that utilizing an article transportation device  122  having at least one of reverse, stop, and lift capabilities may allow a decrease in size and/or output capacity of the manufacturing equipment  120 . For example, a conventional curing station may require a relatively large infrared heater capable of generating a large amount of heat. Specifically, the infrared heater may be sized to adequately cure a coating of paint on an article as it passes through the curing station at a speed equal to an overall line speed. However, the article transportation device  120 , as described herein, may stop and/or reverse the article as it passes through the curing station  26 . Therefore, the manufacturing equipment  120  or, more specifically, the infrared heaters used therein may have a lower heat output requirement. As a result, significant cost savings relative to the manufacturing equipment  120  may be recognized. 
         [0069]    An exemplary control system  220  for the manufacturing chain  10  is shown generally in  FIG. 6 . Specifically, the control system  220  may include the station control systems  124  of each modular manufacturing station within the manufacturing chain  10 , such as the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 . It should be appreciated that the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28  of  FIG. 1  may include configurations similar to any of the embodiments of the first and second modular manufacturing stations  118  and  160  of  FIGS. 2-5 . Specifically, the manufacturing modules  32  of the manufacturing chain  10 , as shown in  FIG. 1 , may each include one or more of the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 , as dictated by the manufacturing process to be performed. 
         [0070]    The station control systems  124  may include any commercially available microprocessors that include means for controlling the operation of at least one of the article transportation device  122  and the manufacturing equipment  120  of the respective manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 . Generally, each station control system  124  may include a processor  222 , a memory  224 , and any other components for running an application. Various circuits may also be associated with the station control systems  124 , such as utility supply circuitry, signal conditioning circuitry, and any other types of circuitry needed for the operation of the respective manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 . 
         [0071]    The station control systems  124  may each receive input from an operator interface  226 , and may control and/or override the operation of the article transportation device  122  and/or manufacturing equipment  120  of the respective manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28  in response to the input. As should be appreciated, the operator interface  226  may receive an operator input command that is indicative of a desired operation. Accordingly, the operator interface  226  may include a touch screen, keyboard, control panel, or any other device or mechanism capable of facilitating communication between the operator and the station control systems  124 . It is also contemplated that the input could alternatively be a computer-generated command from an automated system that assists the operator, or an autonomous system that operates in place of the operator. 
         [0072]    According to one embodiment, the memory  224  of each station control system  124  may include a unique operation pattern corresponding to a specific task stored thereon. For example, the unique operation pattern may include one or more operation signals to be transmitted to at least one of the article transportation device  122  and the manufacturing equipment  120  via at least one communications conduit  228 . Such operation signals may, for example, include the forward signal, the reverse signal, and the stop signal, as described above. In addition, the raise signal and the lower signal may be issued to an article transportation device  122  that includes a vertical lift device, such as vertical lift devices  206  and  212 . Further, operation signals, such as, for example, a begin operation signal and a stop operation signal that may, intuitively, start or stop operation of the manufacturing equipment  120 , may also be issued. It should be appreciated that a “unique operation pattern,” as used herein, may generally refer to any sequence or pattern of movements or operations that facilitate the performance of a task, including such parameters as speed and direction of travel. 
         [0073]    Each of the station control systems  124  may issue an operation signal, as describe above, in response to an operator input or, alternatively, automatically and according to a predetermined pattern, such as corresponding to the unique operation pattern stored thereon. According to one embodiment, the station control systems  124  may be in communication with the position tracking devices  176 ,  178 , and  180  via the communications conduit  228 , and may be configured to receive signals indicative of detected carrier positions. The station control systems  124  may also be configured to issue at least one of the operation signals corresponding to the unique operation pattern, based, at least in part, on one or more of the detected carrier positions. 
         [0074]    A main control system  230  may be provided for coordinating operation of the station control systems  124  of each modular manufacturing station  18 ,  20 ,  22 ,  24 ,  26 , and  28 . Alternatively, however, one of the station control systems  124  may be designated a master control system for coordinating operation of the manufacturing chain  10 . The main control system  230  may be of standard design and may generally include a processor  232 , such as, for example, a central processing unit, a memory  234 , and an input/output circuit, such as the communications conduit  228 . It should be appreciated that the communications conduit  228 , as referenced herein, may represent any form of wired and/or wireless communications, and may generally represent the transmission of any of the operation signals and/or positions signals described above. According to one embodiment, one or more data communications may be transmitted via the utility transfer modules  40 . 
         [0075]    The processor  232  may control operation of the main control system  230  by executing operating instructions, such as, for example, programming code stored in the memory  234 , wherein operations may be initiated internally or externally to the main control system  230 . As should be appreciated, a control scheme may be utilized that monitors outputs of the systems and/or components of each modular manufacturing station  18 ,  20 ,  22 ,  24 ,  26 , and  28 , such as, for example, sensors, actuators, or control units, via the communications conduit  228 . Such information may, for example, be used to control inputs to the station control systems  124  and/or other systems and components of the each of the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 . 
         [0076]    According to one example, the memory  234  of the main control system  230  may store a plurality of unique operation patterns thereon. The main control system  230  may receive signals indicative of the first, second, and third detected carrier positions from each of the station control systems  124 . In response, the main control system  230  may independently transmit operation signals, such as operation signals corresponding to one of the unique operation patterns, to each of the station control systems  124 . The station control systems  124  may, in turn, transmit the operation signals to the article transportation device  122  and/or the manufacturing equipment  120  at the respective stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 . 
         [0077]    The main control system  230  may also index the carriers  164  of each modular manufacturing station  18 ,  20 ,  22 ,  24 ,  26 , and  28  as each carrier  164  traverses to a contiguous station  18 ,  20 ,  22 ,  24 ,  26 , and  28 . According to one embodiment, the main control system  230  may simultaneously issue an index signal to the station control systems  124  of each modular manufacturing station  18 ,  20 ,  22 ,  24 ,  26 , and  28 . As such, the processors  222  of each station control system  124  may be configured to await and/or anticipate the index signal from the main control system  230  after the task to be performed at the respective station has been completed. 
         [0078]    According to one example, indexing may include detecting a desired position of the carrier  164  within each station  18 ,  20 ,  22 ,  24 ,  26 , and  28 , such as by using one or more of the position tracking devices  176 ,  178 , and  180 . The main control system  230  may be configured to await signals from each modular manufacturing station  18 ,  20 ,  22 ,  24 ,  26 , and  28  that are indicative of the desired position and then simultaneously transfer each carrier  164  to a contiguous station  18 ,  20 ,  22 ,  24 ,  26 , and  28 . Additional operation signals, therefore, may also be useful for indexing, such as, for example, the stop signal, a speed adjust signal, a transfer signal, or any other signal useful for detecting and transferring the carriers  164 . 
         [0079]    By coordinating operation of the entire manufacturing chain  10 , the main control system  230  may receive a carrier position signal from one modular manufacturing station and issue an operation signal to another manufacturing stations based, at least in part, on that carrier position signal. For example, it may be desirable to transfer the carrier  164  of modular manufacturing station  18  only when the carrier  164  of the modular manufacturing station  20  has reached a predetermined position, such as a position detected by one or more of the position tracking devices  176 ,  178 , and  180 . It should be appreciated that the main control system  230  may utilize position signals from all of the position tracking devices  176 ,  178 , and  180 , at least in part, to coordinate operation of the entire manufacturing chain  10 . 
         [0080]    The main control system  230  may also include an operator interface, such as an interactive operator display  236 , for continuously monitoring and/or controlling operation of each modular manufacturing station  18 ,  20 ,  22 ,  24 ,  26 , and  28  of the manufacturing chain  10 . According to one embodiment, the interactive operator display  236  may be used to continuously monitor a status of each article transportation device  122  of the manufacturing chain  10 . Further, the interactive operator display  236  may be configured to display a real-time visual representation of each carrier  164  being transported through the manufacturing chain  10 . The interactive operator display  236  may also be configured to receive an operator input command from an operator and transmit the operator input command to the article transportation device  122  or the manufacturing equipment  120  of at least one of the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 . 
         [0081]    It should be appreciated that numerous applications and configurations of the control system  220  are contemplated. According to one embodiment, the main control system  230 , station control systems  124 , position tracking devices  176 ,  178 , and  180 , article transportation devices  122  and manufacturing equipment  120  may all be interconnected through a local area network, as shown in  FIG. 7 . As such, the main control system  230  may directly communicate with the systems and/or components of each modular manufacturing station  18 ,  20 ,  22 ,  24 ,  26 , and  28 , and, therefore, may not direct communications, including operation signals, through the station control systems  124 . Similarly, position signals may be communicated directly from the position tracking devices  176 ,  178 , and  180  to the main control system  230 . 
         [0082]    An exemplary embodiment of a material handling system for use with the modular manufacturing chain  10 , or modular manufacturing line, described herein is shown generally at  250 . The material handling system  250 , only a portion of which is shown, may include a composite beam  252  having an upper rail  254  and a lower track  256  connected through a plurality of spaced apart transverse members  258 . As shown later in greater detail, the lower track  256  may define two parallel channels  260 . A trolley  262 , several of which are shown, may include a lower set of wheels  264  that may be received within the two parallel channels  260  of the lower track  256 . The lower track  256 , along which the trolley  262  is movable, may define a rail of any standard size, including, for example, a 3″, 4″, or 6″ rail. An upper set of wheels  266  of the trolley  262  may be in frictional engagement with a drive tube  268  of a friction drive system  270 . The friction drive system  270 , which may include a spinning tube friction drive system as provided by OCS IntelliTrak of Cincinnati, Ohio, may be similar to an exemplary embodiment of the article transportation device  122  described above, and may generally include a plurality of drive tubes  268  supported along the material handling system  250  and positioned in series to define a path through the modular manufacturing chain  10  ( FIG. 1 ). Each of the plurality of drive tubes  268  may be independently driven, or rotated, by one of a plurality of motors, such as electric drive motor  272 . Therefore, depending on the number and length of independently driven drive tubes  268 , the material handling system  250 , or modular material handling system  250 , may be customized to independently control each article as it is transported through the manufacturing chain  10 . 
         [0083]    As shown in the illustrated embodiment, a first trolley assembly  274  may be configured to support a first load bar  276 . Specifically, a first end  278  of the first load bar  276  may be pivotably supported from a first trolley  280 , while a second end  282  of the first load bar  276  may be pivotably supported from a second trolley  284 . Similarly, second trolley assembly  285  may be configured to support a second load bar  286 . More specifically, a first end  288  of the second load bar  286  may be piovtably supported from a third trolley  290 , and a second end  292  of the second load bar  286  may be pivotably supported from a fourth trolley  294 . A carrier  296 , which may include any devices capable of gripping an article to be conveyed along the modular material handling system  250 , may have a first end  298  pivotably supported from the first load bar  276  and a second end  300  pivotably supported from the second load bar  286 . While a carrier, such as carrier  296 , may be configured to support an article, load bars, such as first and second load bars  276  and  286 , may be configured to evenly distribute weight carried by the carrier  296  among a plurality of trolleys  262 . One skilled in the art should appreciate that a trolley assembly, such as first trolley assembly  274  and second trolley assembly  285 , may include any number of trolleys  262  configured to directly or indirectly support a carrier, such as carrier  296 . Further, a load bar assembly, such as the illustrated load bar assembly  302 , may include any number of trolleys  262  or trolley assemblies  274  and  285  supporting any number of load bars  276  and  286 . Such arrangements may be customized based on the weight to be supported by the carrier  296 . 
         [0084]    According to another arrangement, one or more of the trolleys  262  may include a coupling mechanism for attaching the trolley  262  to another trolley  262 . For example, the front of one trolley  262  may include coupling means configured to attach to complementary coupling means provided on the back of another trolley  262 . Alternatively, similar coupling means may be provided to attach carriers, such as carrier  296 , or load bars, such as load bars  276  or  286 . Any such arrangements may be similar, in purpose, to conventional couplings for attaching train cars to one another for pulling the train cars in a train. As such, one or more trolleys  262 , or carriers  296 , may be transported along the material handling system  250  in a coupled configuration. Such a coupled configuration may, for example, be useful when transporting similar articles or when transporting different articles that may be later combined into an assembly or a sub-assembly. 
         [0085]    Although not depicted, it should be appreciated that a single trolley  262 , which may also be referenced as a trolley assembly, may be configured to directly support a carrier, such as carrier  296 . As such, the friction drive system  270 , and trolley  262 , may be configured to ensure that at least one of the wheels of the upper set of wheels  266  continuously engages one of the drive tubes  268 . Specifically, the wheels of the upper set of wheels  266  may bridge any gaps, such as gap  304 , between drive tubes  268  of the friction drive system  270 . For trolley assemblies, such as trolley assemblies  274  and  285 , which may include one or more trolleys  262  connected through one or more load bars, such as load bar  276 , and/or carriers, such as carrier  296 , it may be important to ensure that at least one of the trolleys  262  continuously engages one of the plurality of drive tubes  268 . 
         [0086]    The trolleys  262 , described herein, may be of standard design, requiring a lower set of wheels  264 , movable along the lower track  256 , and an upper set of wheels  266  that are configured to frictionally engage the plurality of drive tubes  268 . Such trolleys  262 , according to one embodiment, may be modified versions of conventional power and free conveyor trolleys, or other trolleys known to those skilled in the art. To incorporate such standard components, a drive adapter may be provided that attaches a standard trolley, having lower wheels that are movable within the lower track  256 , to the upper set of wheels  266 , described herein. The upper wheels  266 , as should be appreciated, are configured to frictionally engage the plurality of drive tubes  268 . By incorporating such conventional components, such as by slightly modifying standard trolleys as described herein, costs of implementing the material handling system  250  may be reduced. 
         [0087]    Turning now to  FIGS. 9   a - 9   c,  cross-sectional views of alternative embodiments of the composite beam  252  are shown. Specifically, the composite beam  252  of  FIG. 9   a  may include the upper rail  254  and lower track  256  connected through transverse members  258 , as described above with reference to  FIG. 8 . As shown, each of the transverse members  258  may have an inverted U-shaped cross-section defining a pair of free ends  320 . Each of the free ends  320  may support one of channels  260 , which may be generally C-shaped channels, of the lower track  256 . The channels  260 , according to one embodiment, may be welded, or otherwise permanently affixed, to each of the plurality of transverse members  258 . Although alternative attachment methods are contemplated, welding may be preferred to provide increased structural strength of the composite beam  252  and, further, may allow the transverse members  258  to be positioned at longer centers. The upper rail  254 , as shown in  FIG. 9   a,  may, according to one embodiment, include a T-shaped cross-section defining a central web  322  and a transverse flange  324 . The central web  322 , which may extend the length of the composite beam  252 , may be received, and permanently affixed, within a vertically aligned slot  326  of an upper portion  328  of each of the transverse members  258 . 
         [0088]    According to alternative embodiments, shown in  FIGS. 9   b  and  9   c,  the upper rail  254  of the composite beam  252  may include a pair of oppositely oriented structural members  330 . Each of the structural members  330  may include a vertically oriented web  332  that is secured to each of the transverse members  258 . Turning specifically to  FIG. 9   b,  each of the structural members  330  may be in the form of an angle iron having the vertically oriented web  332  and a horizontally oriented flange  334 . The horizontally oriented flange  334 , along with the transverse flange  324  of the embodiment of  FIG. 9   a,  may be used to secure a position of the composite beam  252  along the modular manufacturing chain  10  ( FIG. 1 ), as described below in greater detail. According to this embodiment, and alternative embodiments, the composite beam  252  may also include a horizontally aligned support plate  336  secured to each of the pair of free ends  320  of the transverse members  258  and/or the channels  260  of the lower track  256 . 
         [0089]    The structural members  330 , according to the embodiment of  FIG. 9   c,  may include the vertically oriented webs  332 , which may be attached to the transverse members  258 , and the horizontally oriented flanges  334 , which may be used to attach the composite beam  252  to another structure. In addition, the structural members  330 , as shown in  FIG. 9   c,  may include horizontally oriented flanges  340  that may be fixedly attached to each of the plurality of transverse members  258 . Also shown in the embodiment of  FIG. 9   c,  the composite beam  252  may include a cable tray  342  supported, or defined, by the composite beam  252 . Specifically, the cable tray  342  may extend a length of the composite beam  252  and may be received, and secured, within openings  344  defined by the transverse members  258 . Alternatively, the cable tray  342  may not extend the length of the composite beam  252 , but may be defined only by the openings  344  of the transverse members  258 . The cable tray  342  may be provided to accommodate one or more cables or conduits provided along the manufacturing chain  10 . For example, the cable tray  342  may accommodate the utility transfer module  40 , described above, which may be configured to transfer a utility, such as, for example, electric power, fluid, or data, through the modular manufacturing chain  10  of  FIG. 1 , or another similar chain or line. 
         [0090]    The one or more composite beams  252  of the material handling system  250  may be provided in any desired length, and may include one or more straight and/or curved sections. According to one embodiment, the composite beams  252 , which may be made from iron, steel, aluminum, plastics, composites, and/or any other desired materials, may be provided in specific lengths selected to ease assembly of the modular manufacturing chain  10  of  FIG. 1 . Specifically, the composite beams  252  may be pre-fabricated, or pre-constructed, prior to delivery to the manufacturing area  12  ( FIG. 1 ). Further, each composite beam  252  may be shipped with a predetermined length of cable  356 , an electric drive motor  272 , and a variable-frequency drive  358  for operating the electric drive motor  272 , each of which may be later repositioned. As shown in  FIG. 10 , each composite beam  252  may, according to the exemplary embodiment, be provided in a length corresponding to a length of a manufacturing module  360 . The manufacturing module  360 , which may be similar to the manufacturing module  32  described above, may include, according to one embodiment, a pair of end frames  362  connected through one or more central beams that define a mid-frame  364 . One or more composite beams  252  may be supported from the manufacturing module  32  by attaching, such as by bolting, a plurality of connecting clamps  366  to the composite beam  252  and one or more of the mid-frame  364  and the end frames  362 . Once at least one composite beam  252  is attached to the mid-frame  364  and/or end frames  362 , according to the exemplary embodiment, the end frames  362  may be secured to floor supported beams (not shown). Specifically, end posts  368  may telescopically receive, or may be otherwise attached to, corresponding floor mounted beams (not shown) to form the manufacturing module  360 . Alternatively, rather than end posts  368 , the end frames  362  may include floor mounted support structures having an inverted “V-shape” oriented parallel to the composite beam  252 . 
         [0091]    According to yet alternative embodiments, the one or more composite beams  252  may be supported directly by the building  14 , such as through cables suspended from a ceiling of the building  14 . According to one example, the material handling system  250  may include a combination of ceiling or structure supported composite beams  252  and floor supported composite beams  252 . The ceiling supported composite beams  252 , as should be appreciated, may provide additional clearance for accommodating equipment, such as manufacturing equipment. Yet alternatively, the one or more composite beams  252  may be inverted to provide an on-floor conveyor, rather than the overhead conveyor that has been described. As should be appreciated by those skilled in the art, such an on-floor conveyor may represent an inverted version of the material handling system  250  described herein, with articles and respective carriers positioned, or supported, above the composite beams  252 . 
         [0092]    As described above, a plurality of manufacturing modules  360  may be positioned, such as in series, to define one or more paths through the modular manufacturing chain  10  of  FIG. 1 . The modular material handling system  250 , including one or more composite beams  252  and the friction drive system  270 , described above, may be supported along the one or more paths defined by the manufacturing modules  360 . When supporting the material handling system  250 , it is important to note that the composite beams  252  and friction drive system  270  must be aligned to provide continuous paths, as necessary. It should be appreciated that the friction drive system  270 , as referenced herein, may comprise a plurality of friction drive modules, each of which includes one of the plurality of drive tubes  268  and a corresponding electric drive motor  272 . Therefore, friction drive system  270 , as used herein, may refer generally to the drive system, or material handling system  250 , used throughout the entire modular manufacturing chain  10  ( FIG. 1 ), or to a specific one or more of the modules, or segments, of the friction drive system  270 . 
         [0093]    According to one implementation of the material handling system  250 , shown in  FIG. 11   a,  one or more manufacturing modules  360  of a manufacturing line, such as the manufacturing chain  10  of  FIG. 1 , may include a dual track, or multiple track, assembly. Specifically, as shown in the simplified plan view of  FIG. 11   a,  the material handling system  250  may include a first track assembly  380  configured to transport a forward trolley assembly  382 , including one or more trolleys  262 , along a first path  384 , and a second track assembly  386  configured to transport a trailing trolley assembly  388 , including one or more trolleys  262 , along a second path  390 . Each track assembly  380  and  386  may include one or more composite beams  252  and a friction drive system  270 , as described above. The composite beams  252  of the first and second track assemblies  380  and  386  may be positioned, and/or secured, adjacent one another, without substantial modification, and, as such, may define paths  384  and  390  through one or more modules  360  that are substantially parallel. Together, the parallel paths  384  and  390  may define a transportation path  392  along which the forward trolley assembly  382  and the trailing trolley assembly  388  are spaced. 
         [0094]    A carrier  394 , configured to support an article, may have a first end  396  pivotably supported by the forward trolley assembly  382  and a second end  398  pivotably supported by the trailing trolley assembly  388 . According to a specific arrangement, shown in  FIG. 11   b,  the first end  396  of the carrier  394  may be supported by the forward trolley assembly  382  through a first load bar assembly  410 , while the second end  398  of the carrier  394  may be supported by the trailing trolley assembly  388  through a second load bar assembly  412 . Such a multiple track assembly, including two or more track assemblies, may be used to support articles of a substantial weight, such as, according to some embodiments, up to about 80,000 pounds. According to such arrangements, it may be desirable for the modular material handling system  250  to include at least the first track assembly  380  and the second track assembly  386  throughout the entire manufacturing chain  10 , or line. However, it may be desirable to provide the multiple track assembly in only one or more modules of the manufacturing chain  10 , as will be described below. It should be appreciated that, in such multiple track arrangements, it may be desirable to utilize the friction drive system  270  described herein, which inherently allows slippage, to successfully navigate any curves along the transportation path  392 . Specifically, for example, one of the forward trolley assembly  382  and the trailing trolley assembly  388  may travel a greater distance than the other around such curves. 
         [0095]    According to another implementation, the manufacturing chain  10  may include one or more buffers, such as a buffer  430 , as shown in  FIG. 12 . Specifically, the buffer  430 , which may also be referred to as a sequencing buffer, may include a first track assembly  432  sized to receive at least two trolley assemblies  434 , and a second track assembly  436  that is also sized to receive and support at least two trolley assemblies  434 . According to some implementations, it may be desirable to provide a third track assembly  438 , similar to the first track assembly  432  and the second track assembly  436 , or any number of additional track assemblies. Each of the first, second, and third track assemblies  432 ,  436 , and  438  may be vertically spaced, as shown, or may be otherwise positioned, as described below. 
         [0096]    Each of the track assemblies  432 ,  436 , and  438  may include any number of manufacturing modules  360  positioned such that the material handling system  250  of each track assembly  432 ,  436 , and  438 , including one or more composite beams  252  and a friction drive system  270 , defines a continuous path along the respective track assembly  432 ,  436 , or  438 . According to one embodiment, each module  360  may include one drive tube  268  and a corresponding electric drive motor  272  for transporting the trolley assemblies  434  along the first, second, and third track assemblies  432 ,  436 , and  438  in a forward or reverse direction. As shown, each trolley assembly  434  may include a pair of trolleys  262  configured to support an article  440  using a carrier  442 . It should be appreciated, however, that any number of trolleys  262  may be configured to directly or indirectly support the carrier  442 . 
         [0097]    The buffer  430 , illustrated as a stackable buffer, may also include a first movable track assembly  444  that may include the material handling system  250  described above. The first movable track assembly  444  may be supported by a manufacturing module  360  and may be movable between a plurality of positions. For example, the first movable track assembly  444  may have a first position that defines a continuous path along the first movable track assembly  444  and the first track assembly  432 . A “continuous path,” as used herein, may reference any path along which a trolley  262  may be continuously transported. The first movable track assembly  444  may also include a second position (shown) defining a continuous path along the first movable track assembly  444  and the second track assembly  436 . Further, for embodiments having a third track assembly  438 , the first movable track assembly  444  may have a third position defining a third continuous path along the first movable track assembly  444  and the third track assembly  438 . 
         [0098]    A first programmable hoist  446 , or other similar transfer device, may be configured to move the first movable track assembly  444  between the first, second, and third positions described above. The first programmable hoist  446  may be of conventional design and, further, may be integrated with the control system  220 , described above. The first movable track assembly  444  may be positioned at a first end  448  of the buffer  430 , or at any other desired position along the buffer  430 . Further, the buffer  430 , according to the exemplary embodiment, may include a second movable track assembly  450  positioned at a second end  452  of the buffer  430 . The second movable track assembly  450 , similar to the first movable track assembly  444 , may be movable using a second programmable hoist  454 , or other similar transfer device. Specifically, the second movable track assembly  450  may be movable between a first position (shown) defining a continuous path along the second movable track assembly  456  and the first track assembly  432 , a second position defining a continuous path along the second movable track assembly  450  and the second track assembly  436 , and a third position defining a continuous path along the second movable track assembly  450  and the third track assembly  438 . 
         [0099]    It should be appreciated that the track assemblies  432 ,  436 , and  438  of the buffer  430  may, according to one alternative embodiment, be horizontally spaced, rather than vertically spaced. According to such implementations, the buffer  430  may utilize one or more lateral shuttles, described below, rather than programmable hoists  446  and  454 , to move the movable track assemblies  444  and  450  into alignment with one of the first, second, and third track assemblies  432 ,  436 , and  438 . Such design choices, for example, may be based on spatial constraints of the manufacturing area  12  ( FIG. 1 ) and/or specific needs of the manufacturing processes that are supported. As such, the buffer  430  may include any number of stationary track assemblies, such as track assemblies  432 ,  436 , and  438 , having any desired capacity, positioned and/or stacked according to a customized configuration. Further, the buffer  430  may include any number of movable track assemblies, such as movable track assemblies  444  ad  450 , positioned at any useful positions throughout the buffer  430 . Such a customized buffer  430  may be used to transport, store, sequence, and/or re-sequence carriers  442  and/or articles  440  supported thereon, as described below in greater detail. 
         [0100]    During an exemplary operation, one or more of the trolley assemblies  434  may be distributed among the first track assembly  432  and the second track assembly  436  of the buffer  430  such that a first trolley assembly  456  is blocked from an exit position  458 . The exit position  458  may represent a position within the buffer  430  from which a trolley assembly  434  may be removed from the buffer  430  without having to move another trolley assembly  434 . For example, the exit position  458  may include a position that accommodates a continuous path onto a main path of a manufacturing line. To move the first trolley assembly  456  to the exit position  458 , the plurality of trolley assemblies  434  may be redistributed among the first track assembly  432  and the second track assembly  436 . For example, a second trolley assembly  460 , currently at the exit position  458  and blocking the first trolley assembly  456  from the exit position  458 , may be moved along the first track assembly  432  using the friction drive system  270  and onto the first movable track assembly  444 . The first movable track assembly  444  may then be raised, using the first programmable hoist  446 , from the first position to the second position (shown). At the second position of the first movable track assembly  444 , the second trolley assembly  460  may be moved from the first movable track assembly  444  and onto the second track assembly  436 , using the friction drive system  270 . As a result, the first trolley assembly  456  may be moved along the first track assembly  432  and into the exit position  458 . 
         [0101]    It should be appreciated that, in the exemplary operation described above, the second track assembly  436  was not at its illustrated capacity of three trolley assemblies  434  and, therefore, the second trolley assembly  460  could more easily be moved onto the second track assembly  436 . However, if the second track assembly  436  were supporting a maximum number of trolley assemblies  434 , it may be necessary to move one of the trolley assemblies  434  from the second track assembly  436  to the first track assembly  432 . For example, the second movable track assembly  450  may be moved from the first position (shown) to the second position, described above. Next, a third trolley assembly  462  may be moved along the second track assembly  436  and onto the second movable track assembly  450 . The second movable track assembly  450  may then be lowered, such as by using the second programmable hoist  454 , from the second position to the first position, such that the third trolley assembly  462  may be moved from the second movable track assembly  450  and onto the first track assembly  432 . 
         [0102]    It should also be appreciated that, if both the first track assembly  432  and the second track assembly  436  are at maximum capacity, trolley assemblies  434  may be simultaneously moved, or shifted, through the buffer  430 . For example, the friction drive system  270  of the first track assembly  432  may transport the trolley assemblies  434  in a first direction, while the friction drive system  270  of the second track assembly  436  may transport the trolley assemblies  434  in a second direction that is opposite the first direction. Specifically, the trolley assemblies  434  may be shifted in clockwise direction or a counterclockwise direction through the buffer  430  to move a desired trolley assembly  434  to the exit position  458 . As should be appreciated, to provide such re-sequencing when the buffer  430  is at, or near, maximum capacity, it may be preferable to utilize at least two or more movable track assemblies, such as movable track assemblies  444  and  450 . Further, it should be appreciated that the friction drive system  270  or, more specifically, friction drive modules corresponding to each of the track assemblies  432 ,  436 , and  438  and movable track assemblies  444  and  450  may provide independent movement and control of each of the trolley assemblies  434  positioned therein. 
         [0103]    Turning now to  FIG. 13 , a high level view of a first line  480  is shown. The first line  480  may be similar to, or may include, the modular manufacturing chain  10  described above with reference to  FIG. 1 . Specifically, the first line  480  may include a plurality of stationary modules, such as modules  32  ( FIGS. 1-5 ) or modules  360  ( FIG. 10 ), positioned in series, or in parallel, and defining at least one path  481 , which may include a main path, through the first line  480 . The first line  480  may utilize the material handling system  250 , as described above, including one or more composite beams  252  supporting the friction drive system  270 . Generally, according to one example, the first line  480  may include first operations  482  and a logistics area  484 , both of which may receive articles, such as parts, from suppliers  486 . From first operations  482 , parts, or other articles, may be transported to fabrications  488 , using the material handling system  250 , by supporting the parts using carriers, as described above. From both logistics  484  and fabrications  488 , articles may be transported to paint shop  490  or sub-assembly  492 . 
         [0104]    As shown, the first line  480  may include a plurality of buffers  494 , which may be similar to the buffer  430  described above with reference to  FIG. 12 . The buffers  494  may be positioned anywhere along the first line  480 , such that carriers, and articles supported thereon, may be routed off the one or more main paths  481  and into the buffers  494 . As described above, the buffers  494  may be used to store and/or re-sequence carriers and/or articles. A plurality of spurs  495  may also be provided throughout the first line  480  for storing and/or re-sequencing carriers, in a manner described in greater detail below. Further, the articles may remain on the same carriers continuously throughout the first line  480 , which may span one or more buildings or manufacturing areas. For example, parts and/or sub-assemblies may be stored in one of the buffers  494 , or other storage areas, until they are transported, such as by using a trolley assembly  496 , similar to those described above, to an assembly line  498  or to one or more stations  500  along the assembly line  498 . The articles and/or carriers may be tracked, such as by using barcodes, sensors, and the control system  220  described above, to access and route the parts to the assembly line  498  and/or stations  500  precisely when they are needed. 
         [0105]    A mobile module  502 , having ground-engaging elements  504 , may be used to transport an article, such as a part, sub-assembly, or assembly, from the first line  480  to a second line  520 , as shown in  FIG. 14 . Specifically, the mobile module  502  may be movable between, at least, a first position  506 , as shown in  FIG. 13 , to a second position  522 , as shown in  FIG. 14 . The mobile module  502  may include one or more modules, such as modules  32  ( FIGS. 1-5 ) or  360  ( FIG. 10 ) supported by a frame, such as an enclosed portion of a vehicle or other mobile device. For example, the mobile module  502  may represent a mobile version of one of the stationary modules  32  or  360  described above, and may be movable using any known transportation means. The mobile module  502  may also include a material handling system  250 , including one or more composite beams  252  supporting a friction drive system  270 , as described above. It should be appreciated that in both the first position  506  and the second position  522 , the material handling system  250  of the mobile module  502  may be aligned with a portion of the material handling system  250  of the respective line  480  or  520 , such that a trolley assembly, such as trolley assembly  492 , may be continuously transported along the respective material handling systems  250 . According to another embodiment, the material handling system  250  may provide a continuous path between adjacent buildings. Further, an enclosure may be provided to protect the material handling system  250  and any articles transported thereon from the weather, and other adverse conditions, to which they may be exposed between buildings. As should also be appreciated, transporting an article on its respective carrier may allow the carrier and, thus, article to be tracked while it is transported between remote buildings, locations, etc., as described herein. 
         [0106]    Referring also to  FIGS. 1-13 , the second line  520  of  FIG. 14  may also include a plurality of stationary modules  32  or  360  positioned in series and defining at least one path through the second line  520 . The second line  520  may utilize the material handling system  250 , as described above, including one or more composite beams  252  supporting a friction drive system  270 . Generally, the second line  520  may include one or more track switches, which may each be positioned between two of the plurality of drive tubes  268 . According to one example, a first track switch  524 , which may include a movable track assembly  525 , may be movable between a first position defining a first path  526 , and a second position defining a second path  528 . As shown, the second path  528  may be positioned at an angle that is greater than zero with respect to the first path  526 . By moving the first track switch  524  from the first position to the second position, a carrier, such as carrier  530 , may be transported through the first track switch  524  and onto a spur  532  (as shown). It should be appreciated that the spur  532 , and additional spurs, may be positioned along the second line  520  and used for temporary storage and/or carrier re-sequencing. For example, the carrier  530  may be routed onto the spur  532 , the first track switch  524  may be moved back to the first position, and one or more additional carriers, such as carrier  534 , may proceed along the first path  526  in advance of carrier  530 . 
         [0107]    The spur  532  may also provide a means for turning carriers around. For example, the carrier  530  may be transported, such as in a forward direction, along the second path  528  and past a second track switch  534 . The second track switch  534  may also include a movable track assembly  536  that is movable between a first position defining the second path  528  and a second position defining a third path  538 . After the carrier  532  is moved along the second path  528  and past the second track switch  534 , the second track switch  534  may be moved to the second position, such that the carrier  532  may be moved, in a reverse direction, along the third path  538 . Further, a third track switch  540 , also including a movable track assembly  542 , may be movable between a first position defining the first path  526  and a second position defining the third path  538 . Thus, when the third track assembly  540  is in the second position, the carrier  532  may be transported from the spur  532 , in the reverse direction, and back along the first path  526 , with the article supported by carrier  530  having an orientation that is 180° opposite its previous orientation. 
         [0108]    Additional means for turning around a carrier, such as the carrier  530 , may include movement of a track assembly using a known gantry track, or crane. Specifically, for example, a gantry track, which may provide a fixed structure about which the track assembly may be pivoted, may be used alone or in combination with one or more track switches to reposition a track assembly with respect to a main path, such as the first path  526 . Due to the modularity of the material handling system  250 , gantry tracks, which may be traveling, portable, or fixed, may also be used to move a carrier, such as carrier  530 , between one or more alternative paths, thus operating as a shuttle. Such a shuttle, as should be appreciated, may be used to align a movable track assembly with one of a plurality of track assemblies, thus providing alternative paths for the carrier  530 . 
         [0109]    Track switches, as described above, may be incorporated along the second line  520  for additional purposes. For example, a track switch, such as a fourth track switch  544  having a movable track assembly  546 , may be used to transition a carrier, such as carrier  548 , onto a dual track assembly, which may be similar to the dual track assembly described above with reference to  FIGS. 11   a  and  11   b.  For example, a first trolley assembly  550 , supporting the carrier  548  may be transported through the fourth track switch  544  and along the first path  526 , while the fourth track switch  544  is in a first position. The fourth track switch  544  may then be moved into a second position, which defines a fourth path  552 . As such, a second trolley assembly  554  may be transported along the fourth path  552 , which may be substantially parallel to the first path  526 . It should be appreciated that movement of the first trolley assembly  550  and the second trolley assembly  554  may be controlled to position the carrier  548 , and the one or more articles supported thereon, at any desired angle with respect to the direction of travel. As should be appreciated, there may be one or more modules  360  through which it may be desirable to transport articles at alternative angles, such as, for example, paint or wash modules. Further, it should be appreciated that such diagonal orientation of the carrier  548  may be useful when storing a plurality of carriers, similar to carrier  548 , along a spur, such as spur  532 , or within a buffer, such as buffer  430 . Specifically, a substantial amount of space may be saved by accumulating carriers, such as carrier  548 , at diagonal orientations relative to the direction of travel by providing the dual paths  526  and  552  and track switch  544 , as described above. 
         [0110]    After transporting the carrier  548  through one or more modules  360  at an alternative angle with respect to the direction of travel, a fifth track switch  556  may be positioned along the second line  520  to return the second trolley assembly  554  to the first path  526 . Track switches, such as a sixth track switch  558 , may also be used to route carriers through one or more alternative paths through the second line  520 . For example, the sixth track switch  558  may be used to route carriers along either of the first path  526  and a fifth path  560 . As shown, the first path  526  may include one or more curves, such as curves  562  and  564 . To navigate around such curves, according to one embodiment, a first trolley assembly  564  of a carrier  566  may be disengaged from a first drive tube  568 , while a second trolley assembly  570  of the carrier  566  may be engaged with the first drive tube  568 . As such, the first trolley assembly  564  may be pushed around the curve  562  using the second trolley assembly  570 . As the carrier  566  travels through the curve  562 , the first trolley assembly  564  may engage a second drive tube  572 . The second trolley assembly  570  may eventually disengage from the first drive tube  568 , thus allowing the first trolley assembly  564  to pull the second trolley assembly  570  around the curve  562 . Specifically, for example, such curves  562  may be navigated by positioning drive tubes  568  and  572 , such as linear drive tubes, such that at least one trolley assembly  564  or  570  continuously engages one of the drive tubes  568  and  572 . 
         [0111]    If a carrier, such as a carrier  574 , is transported along the fifth path  560 , a first trolley assembly  576  and a second trolley assembly  578  may ultimately transition the carrier  574  around a curve  580 . When the carrier  574  is positioned along the curve  580 , and the first trolley assembly  576  and the second trolley assembly  578  are stopped, ends  582  and  584  of the carrier  574  may extend beyond a perimeter  586  defined by the curve  580 . When positioned as shown, the carrier  574  may be removed from the fifth path  560  using a programmable hoist  588 . The programmable hoist  588 , which may be of conventional design, may include one or more track assemblies  590  along which the programmable hoist  588  may be movable. Specifically, the programmable hoist  588  may move the carrier  574 , and the article supported thereon, through one or more modules  360 , lowering and raising the carrier  574 , as necessary. The programmable hoist  588 , according to one embodiment, may be supported on its own carrier, which may be supported by one or more trolleys that are movable along track assemblies  590 , as described herein. More specifically, the carrier and trolleys supporting the programmable hoist  588  may operate as a bridge crane moving along the track assemblies  590 , which may serve as runways for the bridge crane. Further, a track assembly, such as track assemblies  590  including one or more composite beams  252 , may be used as the bridge between the runways. Yet further, one of the track assemblies described herein may be configured as a gantry crane, in which one end of the track assembly is pivotable about the other. 
         [0112]    After the carrier  574  is transported through one or more modules  360  using the track assemblies  590  and programmable hoist  588 , the carrier  574 , and article supported thereon, may again be supported on one or more trolley assemblies. Specifically, the carrier  574  may be supported by a first trolley assembly  592  and a second trolley assembly  594 , when the first trolley assembly  592  and the second trolley assembly  594  are positioned around a curve  596  of a sixth path  598 . The sixth path  598  may be positioned to route the carrier back to the first path  526 , as shown. It should be appreciated that the article may remain on the same carrier  574  throughout the transition of the carrier  574  to and from the programmable hoist  588 . It should also be appreciated that this transition, and others described herein, are intended as examples only and, therefore, should not limit the second line  520 , or material handling system  250  thereof, in any way. 
         [0113]    An additional spur  600  may be positioned along the second line  520  to store and/or re-sequence carriers, as described above. Specifically, a seventh track switch  602  and an eighth track switch  604  may be movable to route one or more carriers into and out of the spur  600 . As shown, one or more modules  360  positioned along the spur  600 , and/or other modules, may include a zigzag support frame  606 . Specifically, as an alterative to the end frames  362  and mid-frame  364  of  FIG. 10 , one or more modules  360  may include beams  608 , or headers, that are oriented at an angle, or cross-oriented, with respect to a travel direction through the module  360 . The beams  608  may be attached to end posts  368 , as shown, and may support one or more composite beams  252 , as described above. Although the modules  360  are shown as including two cross-oriented beams  608 , it should be appreciated that each module  360  may include only one beam having an angled orientation with respect to the direction of travel. For example, consecutive modules  360  may include headers, or beams, that are oriented at alternative angles, but that define a continuous zigzag support structure through the modules  360 . Such arrangements, as should be appreciated, may require fewer beams and, therefore, less material for construction of modules  360 . Further, in addition to reduced material cost, such arrangements, utilizing fewer beams, may require less time for assembly of the modules  360 . 
         [0114]    A shuttle, such as a lateral shuttle  610 , may be positioned at an end  612  of the second line  520 , as shown. According to one embodiment, the lateral shuttle  610  may include one or more trolley assemblies, such as any of the trolley assemblies described herein, that are movable along one or more track assemblies, also described herein. The trolley assemblies may support an additional track assembly  614 , oriented perpendicular to the track assemblies along which the trolley assemblies are moved, which is movable to define alternative paths. According to the exemplary embodiment, for example, the track assembly  614  may include a position defining a seventh path  616 , a position defining a continuous path along the first path  526  (shown), and a position defining an eighth path  618 . However, as should be appreciated, such a shuttle  610  may be movable to define any number of alternative paths for one or more carriers, such as a carrier  620 , positioned thereon. 
         [0115]    According to the illustrated embodiment, the track assembly  614  may be moved, such as by using the shuttle  610 , to align with the eighth path  618  of the second line  520 . When the track assembly  614  is positioned to define a continuous path, the carrier  620 , and article supported thereon, may be moved onto the eighth path  618 . As shown, the eighth path  618  may also include a curve  622 , from which the article may be removed from the second line  520 . According to one example, the article may be removed from the second line  520  only for delivery to a customer. Alternatively, however, the article may be transported to a customer using the mobile module  502 , as described herein. If the article is removed from the carrier  620 , the empty carrier  620 , according to one embodiment, may be returned to the track assembly  614 . The shuttle  610  may then be used to move the track assembly  614  to align with the seventh path  616 , which may route the empty carrier  620  to one or more desired locations, such as, for example, a storage buffer  624 , which may be similar to the buffer  430  of  FIG. 12 . According to one example, the seventh path  616  may include one or more composite beams  252 , described herein, which may be supported from one or more modules  360 . Specifically, one or more modules  360  may support one or more composite beams  252  defining a first path through the modules  360 , and one or more composite beams  252  defining an additional path adjacent the modules  360  for empty carrier returns. 
         [0116]    It should be appreciated that alternative arrangements may be used for carrier, or empty carrier, returns. For example, a buffer, such as the buffer  430  described above, may be used to define a first, main, path and a second, return, path. One or more movable track assemblies, such as movable track assemblies  444  and  450  of  FIG. 12 , may be used to transition carriers from the main path to the return path, in a manner similar to that described above. Such transitions, also referred to as an over-under conveyance, may be incorporated, as needed, into the first line  480  and/or the second line  520 . For example, one of the stationary track assemblies of the buffer  430  of  FIG. 12  may be positioned along a main path, such as the main path  481  of the first line  480  or the first path  526  of the second line  520 . Alternatively, one or more carriers may be routed off the main path  481  or first path  526  and into the buffer  430 , such as by actuating one or more track switches, as described herein. 
         [0117]    The carrier  620  may, alternatively, be routed through the shuttle  610  along the first path  526  and, for example, onto a mobile module, such as the mobile module  502 . In a third position  626  (shown) of the mobile module  502 , the material handling system, such as material handling system  250  described herein, of the mobile module  502  may be aligned with the material handling system  250  of the second line  520  such that the carrier  620  may be continuously transported from the first path  526  and onto the mobile module  502 . From there, the mobile module  502  may return the carrier  620 , and article supported thereon, to the first line  480 . It should be appreciated that the first line  480  and the second line  520  may represent one or more manufacturing lines positioned in adjacent buildings or, alternatively, at remote locations. 
         [0118]    The modular material handling system  250 , as described herein with reference to the preceding figures, may be used as a common material handling system throughout an entire manufacturing, or production, process. For example, the material handling system  250  may be used throughout the first line  480  ( FIG. 13 ), the second line  520  ( FIG. 14 ), and any number of mobile modules  502  that may be configured to transport articles between the first line  480  and the second line  520 . Specifically, the same material handling system  250  may be used to route an article through all of the implemented manufacturing processes, including, for example, first operations  482 , logistics  484 , fabrications  488 , paint  490 , sub-assembly  492 , and assembly  498  of the first line  480 . Although specific examples are provided, it should be appreciated that the modular material handling system  250 , as described herein, may be used to support any number and/or combination of manufacturing processes. 
         [0119]    Further, the configuration of the material handling system  250 , including composite beams  252  and friction drive system  270 , as shown in  FIG. 8 , may provide a modular material handling system that may be relatively quickly and easily assembled and/or modified. Specifically, as described with reference to  FIG. 10 , each of a plurality of manufacturing modules  360  may be assembled by connecting a mid-frame  364  to a pair of end frames  362 , and supporting a pre-constructed composite beam  252  from the interconnected frames using one or more connecting clamps  366 . The friction drive system  270 , and other systems or controls, may be supported from the module  360  and, further, may be connected to any necessary utilities via a utility transfer module  40 , as described above. Further, an Andon system, as is known in the art, may be integrated with the any of manufacturing lines  10 ,  480 , and  520  and, further, with the control system  220 . For example, a visual indication of a problem identified, either manually or automatically, at a specific module  32  or  360  may be provided. It should be appreciated that the systems, controls, and equipment used herein may all be provided with plug and play functionality to further ease assembly and/or modification of the manufacturing modules  360 . 
         [0120]    The composite beams  252 , embodiments of which are illustrated in  FIGS. 9   a - 9   c,  and friction drive system  270  of material handling system  250  may support a wide range of weights. Specifically, for example, the composite beams  252  may support any of a variety of articles, ranging from small parts to large sub-assemblies, using one or more trolleys  262  of the friction drive system  270 , which may be configured to directly or indirectly support articles. By supporting such a wide range of weights, the material handling system  250  may be used in a variety of industries, and throughout processes that normally integrate multiple material handling systems or devices, including forklifts, to transport both small and large articles. According to one example, the material handling system  250 , as described herein, may be used to transport both large sub-assemblies and small parts along the main path  481  of the first line  480  ( FIG. 13 ). Specifically, for example, a large sub-assembly may be transported from sub-assembly  492  to the assembly line  498  along path  481 , while a plurality of small parts may be transported from one of the buffers  494  to stations  500  along the same path  481 . Alternatively, either or both of the first line  480  and the second line  520  may integrate a material handling system  250  sized to support lighter weights with a material handling system  250  sized to support heavier weights. Further, such embodiments may incorporate weigh stations along the material handling systems  250  to ensure that trolleys  262  are not routed along paths incapable of providing sufficient support. Alternatively, a control system, such as the control system  220  described above, may track the weight of each article transported along the one or more integrated material handling systems  250  and route respective trolleys  262  accordingly. 
         [0121]    To increase the versatility of the material handling system  250 , a variety of devices and/or features, including, but not limited to track switches, spurs, buffers, programmable hoists, shuttles, and gantry tracks, examples of which are provided herein, may be integrated with the material handling system  250 , as described above. As should be appreciated, these devices and/or features may be utilized by the material handling system  250  to provide numerous and useful transitions of articles throughout a manufacturing, or production, process. Further, the material handling system  250 , and devices or features incorporated therein, may be integrated with a control system, such as the control system  220 , to coordinate the processes for and movements of each article transported along the material handling system  250 . Specifically, by tracking and controlling each article, flow throughout the manufacturing process can be better organized, thus reducing waste and improving efficiency. 
       INDUSTRIAL APPLICABILITY 
       [0122]    The manufacturing chain  10  of the present disclosure may provide a portable and flexible manufacturing chain that supports an improved manufacturing process. Specifically, the manufacturing chain  10  includes manufacturing modules  32  that may be relatively quickly and easily transported and deployed. In addition, modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28  may be readily added to and/or removed from the modules  32  of the manufacturing chain  10 . Further, the article transportation system  30 , and method of operation thereof, may allow independent process control at each modular manufacturing station  18 ,  20 ,  22 ,  24 ,  26 , and  28  and, therefore, may provide improved efficiency with respect to the manufacturing process. Although a paint process is described, it should be appreciated that the manufacturing chain  10 , as described herein, may be used to perform any of a variety of manufacturing processes. 
         [0123]    Referring generally to  FIGS. 1-14 , the manufacturing chain  10 , such as, for example, a paint line, may be deployed by erecting a plurality of manufacturing modules  32 , as needed. Specifically, a plurality of support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104  may be secured to the planar floor  16  of a manufacturing area  12  and may be interconnected to provide a framework or skeleton  80 . One or more of the support beams support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104  may be capable of expansion and/or contraction to further ease the transport and/or deployment of each manufacturing module  32 . The skeleton  80  may provide structural support for one or more modular manufacturing stations, such as, for example, the first modular manufacturing station  118  and the second modular manufacturing station  160  and/or the modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 . Further, the skeleton may include pre-constructed utilities, namely a utility transfer module  40 , supported by one or more of the support beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104 . 
         [0124]    Each modular manufacturing station, such as stations  118  and  160 , may include at least one piece of manufacturing equipment  120 , an article transportation device  122  representing a portion of the article transportation system  30  corresponding to the respective station, and a station control system  124 . It should be appreciated that the manufacturing equipment  120  may be positioned above the planar floor  16  and may be portable to facilitate movement of the equipment  120  from one location, such as a storage location, and into an operable position relative to the station. The manufacturing equipment  120 , as well as the article transportation device  122 , the station control system  124 , and various other systems and/or components of each station  118  and  160  may receive one or more utilities from the utility transfer module  40 . 
         [0125]    It should be appreciated that modifying the manufacturing chain  10 , such as adding or removing a modular manufacturing station may also be accomplished with relative ease. Specifically, a modular manufacturing station, similar to manufacturing stations  116  and  180 , may be added to the manufacturing chain  10  by interconnecting a plurality of beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104  to form a skeleton  80 . The skeleton  80  may be connected to or, alternatively, positioned adjacent a contiguous manufacturing module  32 . A utility transfer module  40 , which may be supported by one of the beams  82 ,  84 ,  86 ,  88 ,  98 ,  100 ,  102 , and  104 , may be connected to a utility transfer module  40  of the contiguous manufacturing module  32  to provide utilities to the added manufacturing station. 
         [0126]    One or more of an article transportation device  122 , a piece of manufacturing equipment  120 , and a station control system  124  may be supported by the skeleton  80 , or otherwise positioned within an operable distance of the added manufacturing station. In addition, one or more of the article transportation device  122 , the manufacturing equipment  120 , and the station control system  124  may be connected to the utility transfer module  40  to receive one or more utilities therefrom, such as using quick connect coupling members, as described above. 
         [0127]    Operation of the manufacturing chain  10  may be controlled and/or coordinated using the control system  220 . Specifically, one or more of the main control system  230  and the station control systems  124  may be configured to advance at least one carrier  164  from a beginning of the manufacturing chain  10  to an end of the manufacturing chain  10 , such as in the forward transport direction “F.” This advancement, according to a specific example, may include independently moving a carrier  164  of the first modular manufacturing station  118  according to a first unique operation pattern and a carrier  164  of the second modular manufacturing station  160  according to a second unique operation pattern. According to one embodiment, the first unique operation pattern may include the forward transport direction “F” and the reverse transport direction “R.” The second unique operation pattern may, for example, include moving the carrier  164  in the vertical direction relative to the transportation path  166 , such as by raising and/or lowering the carrier  164 . 
         [0128]    The memory  234  of the main control system  230  may store the first and second unique operation patterns for controlling operation of the first and second modular manufacturing stations  118  and  160 , respectively, thereon. The first position tracking devices  176  of each modular manufacturing station  118  and  160  may detect a first position of each carrier  164  as it is transported through the respective one of the manufacturing stations  118  and  160 , and transmit first position signals to the main control system  230 . It should be appreciated that any of the operation signals, including position signals, may be transmitted through the station control systems  124 . 
         [0129]    The processor  232  of the main control system  230  may be configured to independently transmit an operation signal corresponding to each of the first and second unique operation patterns to the respective one of the manufacturing stations  118  and  160  based, at least in part, on the detected first positions. For example, the processor  232  may independently transmit one or more operation signals, such as, for example, the forward signal, to each article transportation device  122  upon detecting that each carrier  164  is entering the respective one of the modular manufacturing stations  118  and  160 . Similarly, the processor  232  may be configured to independently transmit one or more operation signals to the manufacturing equipment  120  based, at least in part, on the detected first positions. 
         [0130]    In addition, the second position tracking devices  178  and the third position tracking devices  180  of the manufacturing stations  118  and  160  may detect second and third positions, respectively, and transmit second and third position signals to the main control system  230 , such as through the station control systems  124 . The processor  232  may also be configured to independently transmit an operation signal corresponding to each of the first and second unique operation patterns to the respective one of the manufacturing stations  118  and  160  based, at least in part, on one of the detected second and third positions. Similarly, the processor  232  may be configured to independently transmit one or more operation signals to the manufacturing equipment  120  based, at least in part, on one of the detected second and third positions. 
         [0131]    For example, the processor  232  may be configured to transmit the reverse signal to the article transportation device  122  of the first modular manufacturing station  118  upon detecting that the carrier  164  has reached a predetermined position relative to the manufacturing equipment  120 . Similarly, the processor  232  may be configured to transmit the lower signal to the article transportation device  122 , or second vertical lift device  212 , of the second modular manufacturing station  160  upon detecting that the carrier  164  has reached a predetermined position relative to the manufacturing equipment  120 . Determining that the carrier  164  has reached the predetermined position, in either example, may be based, at least in part, on one of the second and third position signals. 
         [0132]    In addition, the processor  232  of the main control system  230  may be configured to index the carriers  164  of each modular manufacturing station  118  and  160  as each carrier  164  traverses to a contiguous manufacturing station. Indexing may, for example, include detecting one of the second and third positions, as described above, of each carrier  164  and simultaneously transferring each carrier  164  to a contiguous manufacturing station. 
         [0133]    It should be appreciated that manufacturing chain  10 , including a plurality of modular manufacturing stations  18 ,  20 ,  22 ,  24 ,  26 , and  28 , as described herein, may be deployed and/or modified with relative ease. Each modular manufacturing station  18 ,  20 ,  22 ,  24 ,  26 , and  28 , as further exemplified by first and second modular manufacturing stations  118  and  160 , is characterized as having a separate article transportation device  122  that allows each carrier  164  to move independently through the respective station. The control system  220  coordinates the independent movements occurring at each station  18 ,  20 ,  22 ,  24 ,  26 , and  28  and synchronizes the transfer of each carrier  164  to a contiguous one of the modular manufacturing stations to define one overlying process flow for the manufacturing chain  10 . 
         [0134]    It should be understood that the above description is intended for illustrative purposes only, and is not intended to limit the scope of the present disclosure in any way. Thus, those skilled in the art will appreciate that other aspects of the disclosure can be obtained from a study of the drawings, the disclosure and the appended claims.