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CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 13/899,727, filed May 22, 2013, which is a continuation of U.S. patent application Ser. No. 13/010,067, filed Jan. 20, 2011, which is a continuation of U.S. patent application Ser. No. 11/542,753, now U.S. Pat. No. 7,900,402, filed Oct. 4, 2006. 
    
    
     BACKGROUND 
     This disclosure relates to portable seating systems and, more particularly, to a powered telescopic seating riser assembly for a seating system with a multiple of seating configurations drivable between at least an extended position and a stored position. 
     Seating risers are designed for use in auditoriums, gymnasiums, and event halls to accommodate spectators on portable seats, such as folding chairs. Depending on the intended use, a facility may require seating risers that are capable of being moved from a retracted position for storage, to an extended position for use. 
     Heretofore, many conventional seating riser structures have been utilized for nonpermanent seating. These conventional systems generally utilize a series of assemblies having seating risers of given heights which store within close proximity to one another. 
     Because of the temporary nature of the seating used by some organizations and the large storage area required to house non-permanent seating systems when not extended for use, it is desirable to provide a variety of seating configurations with a single non-permanent seating system. With conventional non-permanent seating systems, several assemblies are placed adjacent one another, for instance, to form the seating along an athletic playing surface. Although modular in this sense, conventional non-permanent seating systems have a rise always constant with respect to the run. 
     Some conventional non-permanent seating systems are manually deployed. Although effective, significant manpower and time is typically required to deploy and store the system. Manual deployment and storage may be further complicated by the requirement that the non-permanent seating system needs to be deployed in a generally coordinated manner, otherwise, binding or other complications may result. Since the non-permanent seating system by its vary nature is a relatively large structure, coordination during manual deployment and storage coordination may be relatively difficult. 
     Other conventional non-permanent seating systems drive a wheel system thereof. Such drives require friction with a floor surface such that non-uniform traction may also result in the aforementioned binding. 
     SUMMARY 
     A riser assembly according to an exemplary aspect of the present disclosure includes, among other things, a first skin and a second skin spaced from the first skin. A core is disposed between the first skin and the second skin, the core including a plurality of subpanels. A framework including a plurality of beams is disposed between the first skin and the second skin. The core is received within a space defined by the framework, and a portion of the framework is positioned laterally outside the core. Each of the plurality of subpanels is received within one of a plurality of spaces defined by the framework. The plurality of beams defines a perimeter about each of the subpanels. The first skin, second skin and framework enclose the core. The first skin and the second skin are separate and distinct from the framework. 
     In a further non-limiting embodiment of the foregoing riser assembly, the first skin includes a first material, the second skin includes a second material, and the core includes a third material different from the first and second materials in composition. 
     In a further non-limiting embodiment of the foregoing riser assembly, the third material includes an end-grained balsawood. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, the core comprises a honeycomb structure. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, an access track beam is arranged adjacent to the framework. The access track beam defines a longitudinal slot extending at least partially between each end of the access track beam. The longitudinal slot is configured to selectively receive a mountable accessory. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, each of the first and second skins is glued to the core. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, each of the first and second skins is attached to the framework. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, each of the first and second skins is welded to the framework. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, each of the first and second skins has a substantially identical cross-section profile spanning the core and the framework. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, the first skin, the second skin and the framework define a first deck surface. The framework extends below a second deck surface vertically spaced from the first deck surface. The framework extends substantially between a front facing edge and a rear facing edge of the second deck surface. 
     A riser assembly according to another exemplary aspect of the present disclosure includes, among other things, an upper framework and a lower framework spaced vertically relative to the upper framework and extending substantially between a front facing edge and a rear facing edge of the upper framework, and a deck surface. An access beam is exposed. The access beam defines a longitudinal slot together with the upper framework to receive a riser assembly accessory. 
     In a further non-limiting embodiment of the foregoing riser assembly, the deck surface includes a first skin. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, the deck surface is a first deck surface, and a second deck surface is positioned in a stepped arrangement relative to the first deck surface. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, the first deck surface is attached to the second deck surface to minimize relative movement therebetween. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, the deck surface is attached to the lower framework. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, the access track beam is arranged adjacent to the upper and lower frameworks. The access track beam defines a longitudinal slot extending at least partially between each end of the access track beam. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, the access track beam is arranged adjacent to the upper and lower frameworks. The access track beam defines a longitudinal slot extending at least partially between each end of the access track beam. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, a side of the access track beam is attached to the upper and lower frameworks. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, the access track beam defines at least one flange extending inward from the longitudinal slot. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, the riser assembly accessory is chair beam mounting system secured to the access beam. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, the longitudinal slot is defined by a first channel formed in an upper surface of the access track beam and is also defined by a second channel formed in a lower surface of the upper framework. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, the access track beam extends across and is attached to a plurality of ribs extending substantially between the front facing edge and the rear facing edge of the upper framework. 
     In a further non-limiting embodiment of any of the foregoing riser assemblies, the lower framework extends at least partially below the access track beam. 
     A method of supporting an accessory relative to a riser assembly according to another exemplary aspect of the present disclosure includes, among other things, selectively attaching an accessory to a longitudinal slot defined by a forward facing access track beam that is positioned in a vertical relationship relative to a first deck panel. The longitudinal slot is also defined by a framework of a second deck panel spaced vertically from the first deck panel. 
     In a further non-limiting embodiment of the foregoing method includes selectively attaching an accessory to a longitudinal slot defined by a forward facing access track beam that is positioned in a vertical relationship relative to a first deck panel. The longitudinal slot is also defined by a framework of a second deck panel spaced vertically from the first deck panel. 
     In a further non-limiting embodiment of any of the foregoing methods, the longitudinal slot is defined by a first channel formed in an upper surface of the access track beam and is also defined by a second channel formed in a lower surface of the framework. 
     In a further non-limiting embodiment of any of the foregoing methods, the longitudinal slot is a first longitudinal slot spaced from a second longitudinal slot also defined by the access track beam. 
     In a further non-limiting embodiment of any of the foregoing methods, the access track beam is attached to the framework. 
     In a further non-limiting embodiment of any of the foregoing methods, access track beam is separate and distinct from the framework. 
     In a further non-limiting embodiment of any of the foregoing methods, the access track beam extends across a plurality of ribs vertically spacing the first deck panel and the second deck panel. 
     In a further non-limiting embodiment of any of the foregoing methods, each of the plurality of ribs extends substantially between a front facing edge and a rear facing edge of the framework of the second deck panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
         FIG. 1  is a perspective view of a non-permanent seating system in a deployed position; 
         FIG. 2A  is an exploded view of a dual deck surface; 
         FIG. 2B  is a perspective view of a frame of the dual deck surface of  FIG. 2A ; 
         FIG. 2C  is a sectional view through the dual deck surface illustrating an access track beam; 
         FIG. 2D  is a side view of a section of a non-permanent seating system in a half-deployed position in which only half the seating capacity of each riser assembly is utilized but each seating row provides twice the rise; 
         FIG. 2E  is a perspective view of the non-permanent seating system in a stored position; 
         FIG. 2F  is a perspective view of the non-permanent seating system illustrating one arrangement of rails and stair blocks therefore; 
         FIG. 3A  is a perspective generally bottom view of a single riser assembly; 
         FIG. 3B  is an expanded partially exploded view of a horizontal leg of the telescopic leg assembly of the riser assembly; 
         FIG. 3C  is a perspective generally underside view of the non-permanent seating system in a deployed position illustrating a belt drive system and the interaction of a timing belt between each of the multiple of riser assemblies; 
         FIG. 3D  is a perspective generally rear view of a multiple of the telescopic seat riser systems illustrating the tooth timing belt location; 
         FIG. 3E  is an exploded view of the tooth belt drive system; 
         FIG. 3F  is an exploded view of a guide roller assembly which movably links the riser assembly with the next adjacent riser assembly; 
         FIG. 3G  is a perspective inner view of the locations of the guide assemblies for engagement with a track on an adjacent riser assembly; 
         FIG. 3H  is a view of the tooth belt drive system in an assembled position; and 
         FIG. 4  is a side view of a section of a non-permanent seating system in a fully deployed position. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a general perspective view of a non-permanent seating system  10  having a multiple of telescopic seating riser systems  12 . The telescoping seating riser system  12  forms the fundamental building blocks of the system  10 . The system  12  may stand alone, or may stand side by side. It will be appreciated that the height thereof is dependent on design choices including the desired rise. 
     Each telescopic seating riser system  12  generally includes an innermost lower riser assembly  14 , and successive outer elevated riser assemblies  16 - 24 . It will be appreciated that the number of riser assemblies  14 - 24  in any given telescopic seating riser system  12  will be a matter of design requirements. Each riser assembly  14 - 24  generally includes a dual deck surface  26  and a pair of telescopic leg assemblies  28 . 
     Referring to  FIG. 2A , the dual deck surface  26  includes a lower deck surface  30 A and an upper deck surface  30 B arranged in a stepped arrangement. The lower deck surface  30 A and the upper deck surface  30 B each establish a respective deck plane. The dual deck surface  26  generally utilizes a sandwich structure for each deck panel  32 . The deck panel  32  is manufactured of an upper and lower deck skin  34 A,  34 B which sandwiches a core  36 . The skins  34 A,  34 B are preferably manufactured of aluminum while the core  36  is formed of an end-grained balsawood or a honeycomb structure to provide a strong, lightweight and acoustically absorbent structure. The deck panels  32  are mounted to a framework  38  ( FIG. 2B ) which support a multiple of ribs  40  between a set of longitudinal access track beams  42  (also illustrated in  FIG. 2C ). The core  36  may include a plurality of subpanels  37  (illustrated in  FIG. 2A ) each configured to be received within a space defined by the framework  38 . 
     The multiple of ribs  40  provide the dual deck surface  26  by vertically separating the lower deck panel  32 L from the upper deck panels  32 U. Each riser assembly  14 - 24  includes one dual deck surface  26  with one lower deck panel  32 L and one upper deck panel  32 U to provide seating on two levels. 
     Referring to  FIG. 2C , the longitudinal access track beams  42  include slots  44  which receive a chair beam mounting system S ( FIG. 2D ) such as that utilized in stadium seating systems such as that manufactured by Camatic Pty Ltd. of Wantirna, Australia. The access track beams  42  are arranged in a vertical relationship between each deck panel  32 L,  32 U to provide space for the seating system  10  when in a stored position. The slots  44  are longitudinally located within the access track beams  42  to provide communication passages for, for example only, aisle lighting, and attachment of, for example only, rails R ( FIG. 2F ), stair blocks B ( FIG. 2F ) and the aforementioned chair beam mounting system S. 
     Referring to  FIG. 3A , each telescopic leg assembly  28  includes a horizontal leg  50  and a vertical leg  52 . It should be understood that although only a single leg assembly will be described, it should be understood that each leg assembly on each dual elevated riser assemblies  14 - 24  is generally alike. Notably, each riser assembly  14 - 24  telescopes under the next higher riser assembly  14 - 24 . 
     Each vertical leg  52  is attached to the rear of the dual deck surface  26  through a bracket  54 . The vertical leg  52  is preferably manufactured of square tubing, however, other shapes may likewise be usable with the present invention. 
     A set of rear cross members  56  are connected to the vertical leg  52  at their lower end and to the dual deck surface  26  at their upper end through a central bracket  58 . The rear cross members  56  further stabilizes each riser assembly  14 - 24 . The central bracket  58  is connected to another central bracket  58 ′ on the next riser assembly  14 - 24  through an articulatable linkage  60  which articulates in response to telescopic movement of the riser assemblies  14 - 24 . The linkage  60  preferably provides a passage for the communication of power cables, electronic control and the like. 
     The horizontal leg  50  is supported on wheels  62 . Preferably, four wheels  62  are mounted within each of the horizontal legs  50  to allow each riser assemblies  14 - 24  to readily travel over a floor surface. 
     Referring to  FIG. 3B , each horizontal leg  50  of each leg assembly  28  supports a toothed belt drive system  64 . The belt drive system  64  includes an electric motor  66 , an inner pulley  68 , an outer pulley  70  and a toothed timing belt  72  therebetween. The toothed belt drive system  64  provides the interface between each adjacent riser assembly  14 - 24  ( FIG. 3C ) and the motive force to extend and retract the riser system  12  in a telescopic manner. The toothed timing belt  72  is continuous in this example. That is, the toothed timing belt  72  is a loop lacking a defined end. 
     The electric motor  66  is mounted directly aft of the vertical leg  52  in a readily accessible location. Notably, the power cable  67  from the electric motor  66  is preferably threaded through the associated rear cross members  56  to communicate with the central bracket  58  and a controller C preferably on the uppermost riser assembly  24 . 
     The inner pulley  68  and the outer pulley  70  include a toothed surface to engage the toothed belt with a minimum of slippage. The example toothed surface includes a plurality of vertically extending teeth  73 . The inner pulley  68  and the outer pulley  70  rotate about respective axes generally parallel to the vertical leg  52 . The electric motor  66  includes a shaft  75  directly connected to the inner pulley  68 . The shaft  75  rotates about an axis A that is perpendicular to the direction of movement I of the toothed timing belt  72 . The direction of movement I establishes a belt plane associated with the toothed timing belt  72 . The toothed timing belt  72  preferably faces away from, but is engaged with, each adjacent horizontal leg  50  of the next inner riser assembly  14 - 24  ( FIG. 3D ). That is, the toothed timing belt  72  of the belt drive system  64  on the horizontal leg  50  of the outermost riser assembly  24  faces inward toward its own horizontal leg in direction II. The belt  72 , however, is engaged with the horizontal leg  50  of the next inner riser assembly  22  through a belt clamp  74  ( FIG. 3H ). 
     The toothed timing belt  72  engages the belt clamp  74  located on an outer surface of the adjacent next inner riser assembly  14 - 24  ( FIG. 3E ). Preferably, the belt clamp  74  is located adjacent the intersection of the horizontal leg  50  and the vertical leg  52  and includes a toothed surface which matches the toothed timing belt  72  for engagement therewith. The belt clamp  74  provides the engagement between the toothed timing belt  72  of the outer next inner riser assembly  14 - 24  with the next inner riser assembly  14 - 24  such that rotation of the toothed timing belt  72  drives the next inner riser assembly  14 - 24  relative the associated outer riser assembly  14 - 24 . 
     Referring to  FIG. 3B , a guide assembly  76  along the length of the horizontal leg  50  further guides the inner riser assembly  14 - 24  relative the associated outer riser assembly  14 - 24 . Preferably, a track  78  and guider roller assembly  80  ( FIG. 3G ) provides an effective low friction interface between one inner riser assembly  14 - 24  and the next associated outer riser assembly  14 - 24 . It should be understood that various guide assemblies  76  may be utilized with the present invention. 
     In operation, the pair of each electric motors  66  on each riser assembly  14 - 24  are driven simultaneously by the controller C to fully extend the seating riser system  12  from the storage position ( FIG. 2E ). The controller C provides for programmed stops of each riser assembly  14 - 24  such that the telescopic seating system  10  may be readily deployed to the fully extended position ( FIGS. 1 and 4 ) or to the half-deployed position ( FIG. 2D ). The half-deployed position utilizes only half the seating capacity of each riser assembly  14 - 24  but provides twice the rise between each seating row to thereby accommodate particular venues. The controller C also communicates with each motor  66  such that the telescopic seating system  10  can be assured of straight tracking through torque sensing. Furthermore, the belt drive system  64  assures coordinated deployment as the toothed timing belt  72  minimizes the likelihood of slippage. 
     It will be appreciated that seating system is a load bearing structure intended to hold many people and equipment, such as portable seating, above a floor surface. Therefore, the telescopic seating system is suitably constructed. For instance, the structural members of the telescopic seating system preferably are constructed of thin wall tubing, straight bar stock, right angle bar stock, and plate of suitable materials, for instance, steel, alloy, aluminum, wood or high strength plastics. Components may be joined in any number of conventional manners, such as by welding, gluing or with suitable fasteners. Wheels are preferably of the solid caster type. It will be appreciated that in reference to the wheels, such wheels may be constructed of any device that provides rolling or other relative movement, such as sliding, between respective track surfaces. 
     It should be understood that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are with reference to the normal operational attitude of the system and should not be considered otherwise limiting. 
     The foregoing description is exemplary rather than defined by the limitations within. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.

Summary:
A riser assembly according to an exemplary aspect of the present disclosure includes, among other things, a first skin. A second skin is spaced from the first skin. A core is disposed between the first skin and the second skin. A framework is disposed between the first skin and the second skin. A portion of the framework is positioned laterally outside the core. A method of supporting an accessory relative to a riser assembly is also disclosed.