Abstract:
An improved shipping system includes a base deck section. The system further includes an upper-tier deck section, that moves between a position atop the base deck section through a variety of positions, including positions that put the upper section out of the way of loading and unloading any load on the base deck section. Cartons may be atop both the base deck section and the upper-tier deck section, for shipments, with the upper-tier deck section in the raised configuration. When emptied, the shipping system may be returned with its upper-tier deck section moved down to a position atop the base deck section, and the shipping system stacked upon a similar improved shipping system. Shipping efficiency is increased as much as twenty percent and perhaps more. All components are steel, and may also be plastic, wood and the like.

Description:
PRIORITY INFORMATION 
     This application is a continuation-in-part of U.S. Non-Provisional patent application Ser. No. 12/037,655 filed Feb. 26, 2008, now abandoned, which claims the benefit of priority of U.S. Provisional Application No. 60/946,435, filed Jun. 27, 2007, and also is a non-provisional of U.S. Provisional Application No. 61/392,330, filed Oct. 12, 2010, the contents of which are incorporated by reference in their entirety. 
    
    
     FIELD OF INVENTION 
     This invention relates to the field of shipping packages and objects, to an improved shipping system for shipping such packages and objects, and to the methods of use of such systems and also pallets. 
     BACKGROUND 
     In the past, pallets have been used for shipping packages and objects, which have been typically constructed of rough wood. Some have been used that have been presswood, plastic, and aluminum. Wood pallets typically allow for forklift movement of the pallets and their loads. Some allow forklift access from two opposed sides, and are said to provide 2-way forklift access. Others provide 4-way forklift access. Some have been made “nestable,” or able to be nested one on top another for ease of stacking Some have integrated sidewalls to become containers, and have been collapsible and stackable. Some are made specifically for 55 gallon drums, others specifically for sheetfed press runs, rolls of film, paper and the like, and still others for television display panels. Some are less sturdy, for limited use, and others more sturdy, for extended use. Numerous remain wood pallets of conventional construction. 
     With wood pallets, and even the ones more “high tech,” some shipments suffer greatly with shipment damage. This is especially true with many goods packaged in paperboard and small flute corrugated boxes and cartons, often called folding and folded cartons. The goods in such cartons include many consumer products, from medicines and pharmaceuticals, to foods such as breakfast cereals, pasta and chocolates, through toys, consumer electronics and automotive parts. In these boxes, many products have been damaged and their boxes crushed from forklift damage and their own weight when overstacked. As a result, needs have existed over years and decades for shipping systems that provide improved transportation for more fragile loads such as paperboard loads. The needs include ease of loading and unloading, as well as greater heights of loads without self imposed crushing, and the like. 
     The improved shipping system of this invention was specifically developed to minimize or potentially eliminate crushing, bowing and other damage issues. Increasing the volume of the trailer occupied without fear of having damaged or crushed products is an added benefit that can result in significant freight cost reductions. 
     SUMMARY 
     In a first embodiment, an improved shipping system includes a base deck section. The system further includes an upper-tier deck section, that moves between a position atop the base deck section through a variety of positions, including positions that put the upper section out of the way of loading and unloading any load on the base deck section. Loaded pallets may be atop both the base deck section and the upper-tier deck section, for shipments, with the upper-tier deck section in the raised configuration. When emptied, the system may be returned with its upper-tier deck section moved down to a position atop the base deck section, and the system stacked upon a similar improved system. Shipping efficiency is increased as much as twenty percent and perhaps more. All components are steel, and may also be plastic, wood and the like. 
     To provide the movement of the upper-tier deck section, and support it in the position shown, several legs are provided on each end, extending between the base deck section and the upper-tier deck section. The legs are detachable from the upper-tier deck section and/or the base deck section, and may hook into catches. The legs may lie against the base deck sections. The legs may be hinged at their ends. 
     As described, the upper-tier deck sections provide space between the base deck sections and the upper-tier deck sections for a loaded pallet stacked on and supported by the base deck sections. The upper-tier deck sections also provide for loaded pallets supported by and stacked on the upper-tier deck sections. Shipping costs may be reduced as trucks may be better filled with the systems filled with pallets. The shipping system disclosed may be rented and used multiple times, further improving economy. 
     In another embodiment, an improved shipping system includes a base deck section similar to the first embodiment. The system further includes an upper-tier deck section, similar to the first embodiment. The upper-tier deck section moves again between a position atop the base deck section through a variety of positions, with less concern for positions that put the upper section out of the way of loading and unloading loads on the base deck section. Again, loaded pallets may be atop both the base deck section and the upper-tier deck section, for shipments, with the upper-tier deck section in the raised configuration. When emptied, the system may again be returned with its upper-tier deck section moved down to a position atop the base deck section, with less concern for stacking Shipping efficiency is increased as much as twenty percent and perhaps more. All components are steel, and may also be plastic, wood and the like. 
     With the second embodiment, to provide the movement of the upper-tier deck section, and support it in position, several legs are also provided on each end, extending between the base deck section and the upper-tier deck section. On one side, the legs are detachable from the upper-tier deck section. The legs may lie against the base deck sections. The legs may be hinged at their ends. 
     In a third embodiment, an improved shipping system still includes a base deck section. The system further continues to include an upper-tier deck section, as well. In the third embodiment, the upper-tier deck section is consistently in a position atop the base deck section, and movable through a variety of heights relative to the base deck section. Loaded pallets may be atop both the base deck section and the upper-tier deck section, for shipments, with the upper-tier deck section in the raised configuration and at a height suitable for the height of the loaded pallet put on the base deck section. When emptied, the system may be returned with its upper-tier deck section moved down to a position nearest the base deck section. Stacking is possible, although the first and second embodiments stack more closely together when stacked. Shipping efficiency is continued to be increased as much as twenty percent and perhaps more. All components are steel, and may also be plastic, wood and the like. 
     To provide the movement of the upper-tier deck section, and support it in position, several legs are still provided on each end, extending between the base deck section and the upper-tier deck section. The legs are extendible and retractable between a variety of positions of the upper-tier deck section relative to the base deck section, and may be pinned to chosen lengths of extension and retraction. The legs stand perpendicular to the base deck sections. The legs are fixed to the based deck sections and the upper-tier deck sections. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings that accompany this description include several figures, each described as follows: 
         FIG. 1  is a perspective view from above a corner of the upper-tier deck section of a first preferred embodiment of the invention. 
         FIG. 2  is a perspective view from the same location, with the shipping system of  FIG. 1  collapsed and several shipping systems, similarly collapsed and placed on the shipping system of  FIG. 1 , for shipment of the group of shipping systems, as for example during the return of empty shipping systems to the place of the originating shipment. 
         FIGS. 3 ,  4 ,  5 , and  6  are, respectively, end, side, top and bottom plan views of the shipping system of  FIG. 1 , in the condition of  FIG. 1 . 
         FIGS. 7 through 12  are views in a series of the erection and then, in reverse, collapse, of the shipping system of  FIG. 1  from collapsed configuration, to a folded back and load-ready configuration for loading and/or unloading the base deck section through the raising of the upper-tier for an upper-tier raised configuration for shipping, loading and/or unloading the upper-tier. The demonstrated movements are accompanied by persons loading and unloading the shipping system, as may be desired. 
         FIGS. 13 through 17  are, respectively, a perspective, an end, a side, a top, and an erection view of a second preferred embodiment of invention. 
         FIGS. 18 through 21  are, respectively, a perspective, an end, a side, and a top view of a third preferred embodiment of invention.  FIGS. 19 and 20  include erection images of the third preferred embodiment of invention. 
         FIGS. 22 through 30  are, respectively, a perspective, a top plan view, a side view, a bottom plan view, a cross-section view ( FIG. 26 , along line A-A of  FIG. 23 ), and detail views of a preferred base deck section. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a first preferred embodiment of the invention is a shipping system  10 . Scanning across  FIGS. 1 through 12 , the shipping system may be in an upper-tier raised configuration as in  FIGS. 1 ,  3 - 6 , and  12 , an upper-tier lowered, “stowed” or collapsed configuration as in  FIGS. 2 and 7 , and a variety of configurations between these configurations, as in  FIGS. 8-11 . In the raised configuration, the shipping system  10  is typically in outgoing shipping condition, with a load X on the base or lower deck section, and a load (not shown) on the upper-tier deck section  2 . In the collapsed configuration, the shipping system  10  is typically in inbound or return shipping condition, stacked with other similar shipping systems  10 , and with no load on the pallet sections. The shipping system  10 , consistently, may be loaded, lifted by forklift (not shown), placed on a vehicle (not shown), transported, stored as needed, unloaded, collapsed, and returned for further shipment. Of course, the shipping system may be shipped loaded or unloaded without necessity of immediate return to place of origin after first shipment. 
     In addition to the base deck section  1  and the upper-tier section  2 , the shipping system  10  comprises three pivot rods  12 ,  14 ,  16  and legs  5 ,  6  in pairs, at each end of pivot rods  12 ,  14 ,  16 . The rods  12 ,  14 ,  16  are generally parallel to each other, and spaced about the shipping system  10 , at one edge of the base deck section  1  (rod  12 ), just below the plane of the upper-tier deck section  2  and generally above the rod  12  (rod  14 ), and just below the plane of the upper-tier deck section  2  and opposite the rod  12  (rod  16 ). The pivot rods  12 ,  14 ,  16  provide for pivoting of the legs  5 , upper-tier deck section  2 , and legs  6 , as will be explained. 
     In the raised or erected configuration of  FIG. 1 , the shipping system  10  generally defines a cube, unlike conventional pallets which generally always define a plane. The cube of the shipping system  10  wraps a load X, as in  FIG. 12 , whereas a conventional pallet simply underlies a load. Referring to  FIG. 1  for elements  1 ,  2 ,  5  and  6 , and to  FIG. 12  for load X, the shipping system  10  wraps a load X in that the base deck section  1  underlies the load X, legs  5  lie along one side of the load X, upper-tier deck section  2  overlies the load X, and legs  6  lie along another side of the load X opposite the legs  5 . Legs  5  and pivot rods  12 ,  14  define one end face  18  of the system cube. Legs  6  and pivot  16 , along with the upper outer edge of the base deck section  1  define a second, opposite end face  20 . Similar side faces  22 ,  24 , are formed by the structures of the shipping system  10 , as are upper and lower faces formed by the structures  1  and  2 . 
     The base deck section  1  is substantially square, and formed in the third dimension, top and bottom, to form a sectioned load supporting deck  30 . On the top face the shipping system is sectioned by indentations. On the bottom face the base deck section is additionally formed to have several feet such as foot  32  for supporting the whole of the pallet  10  and providing four sided forklift access. The base deck section  1  is plastic, with horizontal steel rod supports incorporated. 
     The upper-tier deck section  2  defines a second load supporting deck  34  for another load Y, seen in phantom in  FIG. 12 . The second deck  34  is formed by crossrails and plates such as rail  36  and plate  38 , as well as corner and side gussets such as corner gusset  40 . The gussets include lips along the outside edges for the second deck  34 , for contacting and holding a load Y against side to side and end to end slippage. 
     Referring to  FIGS. 7-12 , shipping systems  10  may be manipulated by hand from the collapsed configuration and condition of  FIG. 7  through the loaded configuration and condition of  FIG. 12 . First, the collapsed shipping system  10  may have the upper-tier moved and pivoted in the direction of arrow  42  from the configuration of  FIG. 7 , around the pivot  12 , to the configuration of  FIG. 8 . The configuration and condition is one of being folded back and load-ready, for receiving the load X. The load X may be assembled of cartons by hand on a pallet on the shipping system  10 , or moved in by forklift in the direction of arrow  44 . With the load in place, the upper-tier deck section  2  may be swung in the directions of the arrows  46 ,  48  in  FIG. 9 , to move toward the position of  FIG. 10 . Pivoting continues in the direction of arrows  50 ,  52 , to begin to rotate the upper-tier deck section  2  over the load X. The legs  6 , previously tucked alongside the upper-tier deck section  2 , are then pivoted away from the upper-tier deck section  2 , in the direction of arrow  54 . The legs  5  are also pivoted, in the direction of arrow  55 . As the legs  6  extend away from the upper-tier deck section  2 , an over center latch  56  at one side  22  opens and is latched, to keep the legs  6  fixed in relation to the upper-tier deck section  2 . A pivotal stop  58 , at the base of one leg  5 , slides forward along a slide surface, to a bumper, and blocked against the bumper, stops rotation of the legs  5  at a desired location, as in  FIGS. 1 and 12 . Rotation of the upper-tier deck section  2  and legs  6  continues around the load X. 
     At the completion of erection of the shipping system  10 , and as shown in  FIGS. 1 and 12 , the legs  5 , 6  and upper-tier deck section  2  encircle the load X over the base deck section  1 . The legs  5 ,  6  and upper-tier deck section  2  protect the load X, as well. The legs  5  angle inward over the load X, in an off-vertical position. The legs  6  are essentially upright, i.e., vertical. Two stops pads  60 ,  62  as seen in  FIG. 1  at the far ends of legs  6  from the upper-tier deck section  2 , rest on the base deck section  1 . They extend adjacent an extended lower load retention lip  64  of the base deck section  1 . 
     A load X and if desired a load Y may then be transported and offloaded from the shipping system  10 . 
     As will be noticed in  FIG. 2 , when the loads are removed, numerous shipping systems  10  may be stacked. The lowest-most shipping system  10  constitutes a pallet for all the above-stacked shipping systems  10 , such that the stack may be lifted and transported as a load itself. For stacking, the shipping system  10  has pivot stop  58  lifted and the legs  5  dropped on the base deck section  1 , rotating about the pivot rod  14 . The upper-tier deck section  2  is folded over the legs  5  about the same pivot rod, and brought to rest upside down, i.e., inverted, over the base deck section  1 . Suitable recesses on the surface of the base deck section  1  match the side edges of the gussets of the upper-tier deck section. The overcenter latch is  56  released, and the legs  6  dropped atop the stack. The configuration of  FIGS. 7 and 2  is achieved. 
     When chosen, the cycle of shipping system erection, transport of loads, stowage, and transport of shipping systems alone may begin again. 
     Referring to  FIG. 13 , a second preferred embodiment of the invention is also a shipping system,  10 ′. Scanning across  FIGS. 13-17 , and referring back to  FIGS. 2 and 7 , the shipping system may be in an upper-tier raised configuration as in  FIGS. 13-16 , an upper-tier lowered, “stowed” or collapsed configuration similar to that of the first preferred embodiment in  FIGS. 2 and 7 , and a variety of configurations between these configurations, as in  FIG. 17 . In the raised configuration, the shipping system  10 ′ is typically in outgoing shipping condition, with a load (not shown) on the base or lower deck section  1 ′, and a load (not shown) on the upper-tier deck section  2 ′. In the collapsed configuration, the shipping system  10 ′ is typically in inbound or return shipping condition, stacked with other similar shipping systems  10 ′, and with no load on the pallet sections. The shipping system  10 ′, consistently, may be loaded, lifted by forklift (not shown), placed on a vehicle (not shown), transported, stored as needed, unloaded, collapsed, and returned for further shipment. Of course, the shipping system  10 ′ as with system  10 , may be shipped loaded or unloaded without necessity of immediate return to place of origin after first shipment. 
     In addition to the base deck section  1 ′ and the upper-tier section  2 ′, the shipping system  10  comprises three pivot rods  12 ′,  14 ′,  16 ′ and legs  5 ′,  6 ′ in pairs, at each end of pivot rods  12 ′,  14 ′,  16 ′. The rods  12 ′,  14 ′,  16 ′ are generally parallel to each other, and spaced about the shipping system  10 ′, at one edge of the base deck section  1 ′ (rod  12 ′), just below the plane of the upper-tier deck section  2 ′ and generally above the rod  12 ′ (rod  14 ′), and just below the plane of the upper-tier deck section  2  and opposite the rod  12 ′ (rod  16 ′). The pivot rods  12 ′,  14 ′,  16 ′ provide for pivoting of the legs  5 ′, upper-tier deck section  2 ′, and legs  6 ′, as will be explained. 
     In the raised or erected configuration of  FIG. 13 , the shipping system  10 ′ generally defines a cube, unlike conventional pallets which generally always define a plane. The cube of the shipping system  10 ′ wraps a load, whereas a conventional pallet simply underlies a load. Referring to  FIG. 13  for elements  1 ′,  2 ′,  5 ′ and  6 ′, as with the first embodiment  10 , the shipping system  10  wraps a load in that the base deck section  1 ′ underlies the load, legs  5 ′ lie along one side of the load, upper-tier deck section  2 ′ overlies the load, and legs  6 ′ lie along another side of the load opposite the legs  5 ′. Legs  5 ′ and pivot rods  12 ′,  14 ′ define one end face  18 ′ of the system cube. Legs  6 ′ and pivot  16 ′, along with the upper outer edge of the base deck section  1 ′ define a second, opposite end face  20 ′. Similar side faces  22 ′,  24 ′, are formed by the structures of the shipping system  10 ′, as are upper and lower faces formed by the structures  1 ′ and  2 ′. 
     The base deck section  1 ′ is substantially square, and formed in the third dimension, top and bottom, to form a sectioned load supporting deck  30 ′. On the top face the shipping system is sectioned by indentations. On the bottom face the base deck section is additionally formed to have several feet such as foot  32 ″ for supporting the whole of the system  10 ′ and providing four sided forklift access. The base deck section  1 ′ is plastic, with horizontal steel rod supports incorporated. 
     The upper-tier deck section  2 ′ defines a second load supporting deck  34 ′ for another load (not shown). The second deck  34 ′ is formed by crossrails and plates such as rail  36 ′ and plate  38 ′, as well as corner and side gussets. The gussets include lips along the outside edges for the second deck  34 ′, for contacting and holding a load against side to side and end to end slippage. 
     Referring primarily to  FIG. 17 , shipping systems  10 ′ may be manipulated by hand from a collapsed configuration and condition similar to  FIG. 7  through a loaded configuration and condition as in  FIG. 13 . First, the collapsed shipping system  10 ′ may have the upper-tier deck section  2 ′moved and pivoted in the direction of arrow  42 ′ from the configuration like  FIG. 7 , around the pivot  12 ′, to a configuration like that of FIG.  7 . The configuration and condition is one of the upper-tier deck section  2 ′ being folded back. Next, and different than with system  10 , the legs  6 ′ and rod  16 ′ form a leg-rod unit  6 ′- 16 ′, and rotate about a pivot axis  17 ′ formed by another pivot rod or pivot pins between the lower-tier deck section  1 ′ and the legs  6 ′. Consistent with this configuration, the leg-rod unit  6 ′- 16 ′ is lifted and rotated from being adjacent the lower-tier deck section  1 ′ about the pivot axis  17 ′ to the position of  FIG. 17 , in the direction of arrow  43 ′. With the load not yet in place, the upper-tier deck section  2 ′ may be swung upward in the direction of the upward pointing end of the arrow  51 ′ in  FIG. 17 , to move toward the position of  FIG. 17 . The leg-rod unit  6 ′- 16 ′ is then pulled under the upper tier deck section  2 ′ to support the section  2 ′. Over center latches at all four corners of upper tier deck section  2 ′ are opened and latched, to keep the legs  5 ′ and  6 ′ fixed in relation to the upper-tier deck section  2 ′. 
     As with system  10 , the load may be assembled of cartons by hand on a pallet on the shipping system  10 ′, or moved in by forklift as in the direction of arrow  44  in  FIG. 7 . 
     At the completion of erection and loading of the shipping system  10 ′, and as with system  10  as shown in  FIGS. 1 and 12 , the legs  5 ′,  6 ′ and upper-tier deck section  2 ′ encircle the load over the base deck section  1 ′. The legs  5 ′,  6 ′ and upper-tier deck section  2 ′ protect the load, as well. The legs  5 ′ and  6 ′ are essentially upright, i.e., vertical. 
     As with system  10  and its loads X and if desired Y, with system  10 ′, loads may be transported and offloaded from the shipping system  10 ′. 
     Also as with system  10  and its  FIG. 2 , when the loads are removed, numerous shipping systems  10 ′ may be stacked. The lowest-most shipping system  10 ′ constitutes a pallet for all the above-stacked shipping systems  10 ′, such that the stack may be lifted and transported as a load itself. For stacking, the shipping system  10 ′ has the leg-rod unit  6 ′- 16 ′ dropped on the base deck section l′, rotating about the pivot axis  17 ′. The upper-tier deck section  2 ′ is folded against the legs  5 ′ about the pivot rod  14 ′, and both the deck section  2 ′ and the legs  5 ′ are brought to rest with the deck section  2 ′ upside down, i.e., inverted, over the base deck section  1 ′. Suitable recesses on the surface of the base deck section  1 ′ match the legs  5 ′,  6 ′ and upper tier deck section  2 ′ for compactness. 
     When chosen, the cycle of shipping system erection, transport of loads, stowage, and transport of shipping systems alone may begin again. 
     Referring to  FIG. 18 , a third preferred embodiment of the invention is also a shipping system,  10 ″. Scanning across  FIGS. 18-21 , and comparing them to  FIGS. 2 and 7 , the shipping system  10 ″ may be in an upper-tier raised configuration as in phantom in  FIGS. 19-20 , an upper-tier lowered, “stowed” or “collapsed” configuration similar to that of the first preferred embodiment in  FIGS. 2 and 7 , but as shown in solid lines in  FIGS. 19-20 , and a variety of configurations between the positions shown in phantom and solid line in  FIGS. 19-20 . Thus, the system  10 ″ is a linear, as opposed to pivoting, system of movement between the raised and lowered positions. In the raised configuration, the shipping system  10 ″ is typically in outgoing shipping condition, with a load (not shown) on the base or lower deck section  1 ″, and a load (not shown) on the upper-tier deck section  2 ″. In the collapsed configuration, the shipping system  10 ″ is typically in inbound or return shipping condition, stacked with other similar shipping systems  10 ″, and with no load on the pallet sections. The shipping system  10 ″, consistently, may be loaded, lifted by forklift (not shown), placed on a vehicle (not shown), transported, stored as needed, unloaded, collapsed, and returned for further shipment. Of course, the shipping system  10 ″ as with the systems  10  and  10 ′, may be shipped loaded or unloaded without necessity of immediate return to place of origin after first shipment. 
     In addition to the base deck section  1 ″ and the upper-tier section  2 ″, the shipping system  10  deletes pivot rods such as  12 ,  14 ,  16  and  12 ′,  14 ′,  16 ′ in favor of fixed attachment of legs  5 ″,  6 ″ to the deck sections  1 ″ and  2 ″. The legs  5 ″,  6 ″ are formed in two parts, upper leg sections  105 ,  106  and lower leg sections  115 ,  116 . The sections  105 ,  106 ,  115  and  116  include matching pin openings such as the one marked  111  by example, at equally spaced intervals. A V-slot such as the one marked  113  is formed atop each lower leg section  115 ,  116 . Pins (not shown) are placed in the matching pin openings at the V-slots and immediately below the V-slots as well. The pins fix the vertical distance between the upper-tier deck section  2 ′ and the base deck section  1 ′. With multiple pin openings in the upper leg sections  105 ,  106 , the vertical distance is adjustable with removal and relocation of the pins. 
     As with the systems  10  and  10 ′, in the raised or erected configuration, in phantom in  FIGS. 19-20 , the shipping system  10 ″ generally defines a cube, unlike conventional pallets which generally always define a plane. The cube of the shipping system  10 ″ also wraps a load. Legs  5 ′ and parts of the deck sections  1 ″,  2 ″ define end faces of the system cube. Similar side faces are formed by the structures of the shipping system  10 ″, as are upper and lower faces formed by the deck sections  1 ″ and  2 ″. 
     Referring to  FIGS. 22-30 , a specifically preferred base deck section is designated  1001 . Base deck section  1001  forms a planar upper surface in multiple (four) segments  1002 ,  1003 ,  1004  and  1005 . Each segment  1002 - 1005  is elongated in the direction of the length of the base deck section  1001 , relative to the width of each segment  1002 - 1005  in the transverse direction. Segments  1002  and  1005  are mirror images of each other, as are segments  1003  and  1004 . Recesses, to be described, interrupt the planar upper surface, and thereby cause the segments  1002 - 1005  to have shapes other than rectangular. 
     Elongated longitudinal channels  1007 ,  1009  and  1011  as in  FIG. 27  especially also join the segments. At the slot ends, plates at multiple (four) locations such as  1013  in  FIG. 29  are bolted across the outer slots  1007 ,  1011 , for further rigidity. 
     Central recess element  1015 , (two) centered side recess elements such as  1017 , (four) corner recess elements such as  1019  and (four) end recess elements such as  1021  extend below the planar upper surface of the section  1001  and form both feet for the section  1001  and slots for fork lift forks. Forks may pick the deck section  1001  up from either side and either end. The central recess element  1015  is substantially rectangular and square, as are the corner recess elements such as  1019 . The end recess elements such as  1021  are also substantially rectangular, while the side recess elements such as  1017  take the form of swept-wing recesses intersected by a transverse truss or hump, when seen from above. Adjacent each corner recess element such as  1019 , a subplanar element is rectangular, and has an elevation nearer the planar upper surface than the bottom of the corner recess element. Adjacent each end recess element, another subplanar element is formed, and abbreviated subplanar elements are adjacent each end of the central recess element  1015 . Outer side channels such as  1023  receive steel elements along the sides of the section  1001  that join the end elements of the associated legs, as in the third preferred embodiment. Outer end, transverse slot elements such as  1025  provide for pivot rods such as  12  in the first preferred embodiment.