Patent Publication Number: US-2007108204-A1

Title: Foldable container

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims priority from, and incorporates by reference the disclosure of, U.S. Provisional Patent Application No. 60/714,756, which was filed on Sep. 6, 2005. 
    
    
     BACKGROUND OF THE INVENTION  
      1. The Technical Field  
      The present invention is directed generally to collapsible containers and more particularly to collapsible shipping and storage containers and methods of using same.  
      2. The Prior Art  
      Known shipping and storage containers typically have fixed dimensions and occupy the same physical volume whether full or empty. Although this shortcoming is tolerable when the containers are in use, it adversely affects the cost of storing or transporting the containers when empty. Prior attempts to reduce the volume of an unused container typically involve dismantling the container by removing the sides, ends, and top, and stacking these pieces on the bottom. Such dismantling is labor intensive and time consuming, requires substantial rigging, and yields a number of easily lost and essential loose parts, e.g., the fasteners used in assembling the sides, ends, top, and bottom of the container. As such, there is a need for containers that are sufficiently robust to handle the rigors of shipping and storing voluminous and/or heavy cargo but can be easily and quickly broken down to a self-contained, compact form for storage or transport when empty.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a front perspective view of a foldable container in a deployed state according to the present invention;  
       FIG. 2  is a front perspective view of a foldable container in a partially-collapsed state according to the present invention;  
       FIG. 3  is a perspective view of a foldable container in a collapsed state according to the present invention;  
       FIG. 4  is a rear perspective view of the framework of a foldable container in a partially deployed state according to the present invention;  
       FIG. 5  is a rear perspective view of the framework of a foldable container in a deployed state according to the present invention;  
       FIG. 6  is an exploded view of the framework of a foldable container according to the present invention;  
       FIG. 6A  is a detail view of a portion of the framework of a foldable container according to the present invention;  
       FIG. 6B  is a detail view of a portion of the framework of a foldable container according to the present invention;  
       FIG. 6C  is a detail view of a portion of the framework of a foldable container according to the present invention; and  
       FIG. 6D  is a detail view of a portion of the framework of a foldable container according to the present invention.  
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS  
       FIGS. 1-3  illustrate a foldable container according to a preferred embodiment of the present invention in deployed, partially-collapsed, and collapsed states, respectively. Foldable container  10  includes floor  12 , roof  14 , side walls  16 , 18 , rear wall  20 , and front end  22 . Each of side walls  16 , 18  typically includes an upper portion  16 U, 18 U and a lower portion  16 L, 18 L. Preferably, upper side walls  16 U, 18 U define the upper half of side walls  16 , 18  and lower side walls  16 L, 18 L define the lower half of side walls  16 , 18 . Roof  14 , side walls  16 , 18 , and rear wall  20  typically include a skin  24 R, 24 SW, 24 RW, respectively, that protects the contents of container  10  from the elements and provides a barrier to unauthorized access to the interior of container  10 .  
      Front end  22  typically is configured to provide access to the interior of container  10 . Preferably, container  10  includes overhead door  26  that can be moved between a first, deployed position wherein door  26  closes an opening defined by front end  22  of container  10  and a second, retracted position wherein door  26  nests with or within roof  12 , as will be described further below. In preferred embodiments, door  26  is made from roll-formed metal sheeting as would be used to make a conventional metal roll-up door. Such doors are commonly used on the rear of delivery trucks and in connection with concession service windows at sports stadiums. In alternate embodiments, door  26  can be a conventional single- or multi-panel overhead door (not shown) that may or may not include a swinging service door (not shown), as would be known to one skilled in the art. In other alternate embodiments, door  26  can retract into floor  12 . Front end  22  and door  26  can be embodied in other forms as well, as would be apparent to one skilled in the art. Means (not shown), such as an integral locking mechanism or hasp for receiving a padlock, can be provided for securing door  26  in a “closed” position to preclude unauthorized access to the interior of container  10 .  
       FIGS. 4-6  illustrate the framework  30  of container  10  in partially-deployed and deployed states, respectively, according to a preferred embodiment of the present invention. In this embodiment, framework  30  includes floor frame  32 , roof frame  34 , side wall frames  36 , 38 , rear wall frame  40 , and front end frame  42 . Each of side wall frames  36 , 38  includes an upper portion  36 U, 38 U and a lower portion  36 L, 38 L.  
      Floor frame  32  typically includes a perimeter rim defining the sides and ends of floor frame  32 . In the illustrated embodiment, the perimeter rim is defined by side rails  44  and joists  46  spanning the ends of side rails  44  crosswise. Additional joists  46  are shown spanning side rails  44  intermediate the ends of side rails  44 . In other embodiments, joists  46  can span a pair of end rails lengthwise. Stiffeners, braces, and the like (not shown) can be provided to strengthen floor frame  32 , as would be known to one skilled in the art. Decking  28  is installed on floor frame  32  to provide a loadable floor inside container  10 . Decking  28  typically is made of a suitable grade and thickness of plywood, but decking  28  could be made of other materials, as well, as would be known to one skilled in the art.  
      Roof frame  34  typically includes perimeter rim  48  defining the sides and ends of roof frame  34  and rafters  50  spanning and connected to perimeter rim  48 . Roof frame  34  also can include stiffeners or braces  52  and/or other structural members connected to one or more of perimeter rim  48 , rafters  50 , and/or other structural members to provide strength to roof frame  34 , as would be known to one skilled in the art. Preferably, roof frame  34  also includes a second perimeter rim  48 A parallel to and offset from perimeter rim  48  by means of short columns  49 . See  FIG. 6  (where a portion of perimeter member  48 A has been cut away for clarity). This design provides additional volume (compared to embodiments lacking second perimeter rim  48 A and short columns  49 ) within roof frame  34  for receiving door  26  and enclosing and protecting related components, as will be discussed further below.  
      In preferred embodiments, roof frame  34  includes overhead door tracks  54  which receive the side edge portions of door  26  when door  26  is located in and moved to and from the retracted position. See  FIGS. 6 and 6 A. In such embodiments, as would be understood by one skilled in the art, roof frame  34  also can include guide rollers  56  to facilitate moving door  26  between the retracted position wherein door  26  is positioned in door tracks  54  associated with roof frame  34 , as shown in  FIG. 4 , and the deployed position wherein door  26  is positioned in door tracks  76  associated with front end  22 , as shown in  FIG. 1  and as will be discussed further below. Guide rollers  56  typically are connected to perimeter member  48  of roof frame  34  by means of brackets  57 . Brackets  57  can fixed to perimeter member  48  or rotatably connected to perimeter member  48  so that bracket  57  and guide rollers  56  can be rotated from a deployed position wherein guide rollers  56  and portions of brackets  57  may extend outside (and, more particularly, below) the volume defined by roof frame  34 , as discussed above and as shown in  FIGS. 6 and 6 A, to a stored position (not shown) wherein guide rollers  56  and brackets  57  are more fully enclosed by the volume defined by roof frame  34 .  
      Each of upper side wall frames  36 U, 38 U preferably includes a perimeter rim  58 U defining the top, bottom, and ends of the respective upper side wall frame. Typically, perimeter rim  58 U includes a bottom member  60 U, a top member  62 U, and a pair of columns  64 U spanning the ends of the bottom and top members. Additional columns  64 U may be provided intermediate the columns  64 U spanning the ends of bottom member  60 U and top member  62 U, as shown in  FIGS. 4 and 5 . Braces and/or stiffeners (not shown) may be included to provide adequate strength to the upper side wall frames, as would be known to one skilled in the art.  
      Upper side wall frames  36 U, 38 U are hinged to roof frame  34  so that upper side wall frames  36 U, 38 U can be folded inwardly and substantially flatly against the bottom of roof frame  34  when container  10  is in the collapsed state and unfolded such that upper side wall frames  36 U, 38 U are substantially perpendicular to roof frame  34  when container  10  is in the deployed state. In the preferred embodiment, one or more conventional hinges  66  are used to connect upper side wall frames  36 U, 38 U to roof frame  34 . Alternative embodiments can use any other suitable hinge mechanism, as would be known to one skilled in the art.  
      Similarly, each of lower side wall frames  36 L, 38 L preferably includes a perimeter rim  58 L defining the top, bottom, and ends of the respective lower side wall frame. Typically, perimeter rim  58 L includes a bottom member  60 L, a top member  62 L, and a pair of columns  64 L spanning the ends of the bottom and top members. Additional columns  64 L may be provided intermediate the columns  64 L spanning the ends of bottom member  60 L and top member  62 L, as shown in  FIGS. 4 and 5 . Braces and/or stiffeners (not shown) may be included to provide adequate strength to the lower side wall frames, as would be known to one skilled in the art.  
      Lower side wall frames  36 L, 38 L are hinged to floor frame  32  so that lower side frames  36 L, 38 L can be folded inwardly and substantially flatly against the top of floor frame  32  when container  10  is in the collapsed state and unfolded such that lower side wall frames  36 L, 38 L are substantially perpendicular to floor frame  32  when container  10  is in the deployed state. In the preferred embodiment, one or more conventional hinges  68  are used to connect lower side wall frames  36 L, 38 L to floor frame  32 . Alternative embodiments can use any other suitable hinge mechanism, as would be known to one skilled in the art.  
      Upper side wall frames  36 U, 38 U are hinged to corresponding lower side wall frames  36 L, 38 L so that upper side wall frames  36 U, 38 U can be folded substantially flatly against corresponding lower side wall frames  36 L, 38 L when container  10  is in the collapsed state. When container  10  in the deployed state, upper side wall frames  36 U, 38 U and lower side wall frames  36 L, 38 L are substantially coextensive such that each pair of corresponding upper side wall frames  36 U, 38 U and lower side wall frames  36 L, 38 L defines a substantially planar side wall  16 , 18 . In the preferred embodiment, one or more conventional hinges  70  are used to connect upper side wall frames  36 U, 38 U to lower side wall frames  36 L, 38 L. Alternative embodiments can use any other suitable hinge mechanism, as would be known to one skilled in the art.  
      Rear wall frame  40  includes a perimeter rim  86  that defines the top, bottom, and sides of rear wall frame  40 . Perimeter rim  86  includes a bottom member  88 , a top member  90 , and a pair of columns  92  spanning the ends of bottom and top members,  88 , 90 , respectively. Rear wall frame  40  can include additional columns (not shown) intermediate the columns  92  spanning the ends of bottom and top members,  88 , 90 , a cross-member  94 , and additional braces and/or stiffeners (not shown) for strength, as would be known to one skilled in the art.  
      Rear wall frame  40  preferably is hinged to floor frame  32  so that rear wall frame  40  can be folded inwardly and substantially flatly against the top of floor frame  32  when container  10  is in the collapsed state and unfolded so that rear frame  40  is substantially perpendicular to each of floor frame  32 , roof frame  34 , and side wall frames  36 , 38  when container  10  is in the deployed state. In the illustrated embodiment, hinge pins  72  are used to connect rear wall frame  40  to floor frame  32 . Alternative embodiments can use any other suitable hinge mechanism, for example, conventional leaf-type hinges, as would be known to one skilled in the art.  
      Front end frame  42  includes a perimeter rim  96  that defines the top and sides of front end frame  42 . Perimeter rim  96  includes top member  98  and a pair of columns  100  extending from top member  98 . Front end frame  42  can further include one or more cross-members (not shown) and braces and/or stiffeners (not shown) for strength, as would be known to one skilled in the art. Any such additional members preferably are located so as to not impede access to the interior of, or create a trip hazard within or near the entry of, container  10 .  
      Front end frame  42  preferably is hinged to floor frame  32  so that front end frame  42  can be folded inwardly and substantially flatly against the top of floor frame  32  when container  10  is in the collapsed state and unfolded so that front end frame  42  is substantially perpendicular to floor frame  32 , roof frame  34 , and side wall frames  36 , 38  when container  10  is in the deployed state. In the preferred embodiment, hinge pins  74  are used to connect the lower ends of columns  100  of front end frame  42  to floor frame  32 . Alternative embodiments can use any other suitable hinge mechanism, as would be known to one skilled in the art. In preferred embodiments, front end frame  42  includes door tracks  76  (see  FIG. 6 ; door tracks  76  have been omitted from the other drawings for clarity) which receive the side edge portions of door  26  when door  26  is positioned in and moved to and from the deployed position, as shown in  FIG. 1 .  
      In preferred embodiments, stop plates  104  are provided at both ends of framework  30  in connection with roof frame  34  and the upper and lower portions of side wall frames  36 , 38  to prevent rotation of rear wall frame  40  and front end frame  42  more than about 90 degrees from the collapsed position against floor  12  so that rear wall frame  40  and front end frame  42  can be easily indexed to their respective deployed positions. In such embodiments, stop plates  104  preferably are connected to columns  64  defining the ends of the upper and lower portions of side wall frames  36 , 38  and the ends of perimeter rim  48  of roof frame  34 . Gasket material (not shown), for example, conventional weatherstrip, can be provided in connection with stop plates  104  to provide a form of seal between roof frame  34 , side wall frames  36 , 38 , rear wall frame  40  and front end frame  42 . Gasket material (not shown) also can be provided in connection with the joints between floor  12  and rear wall frame  40 , floor  12  and lower side wall frames  36 L, 38 L, lower side wall frames  36 L, 38 L and upper side wall frames  36 U, 38 U, and upper side wall frames  36 U, 38 U and roof frame  34 . Further, gasket material (not shown) can be provided at the bottom of door  26 , adjacent the side of door  26  and door tracks  76 , and along top member  98  of front end frame  42  to form a seal between door  26 , floor  12 , front end frame  42 , and side walls  16 , 18  when door  26  is in the closed position.  
      In other embodiments, either or both of rear wall frame  40  and front end frame  42  can be completely detachable from floor frame  32 , and hinge pins  72  and/or hinge pins  74  (or other, alternate hinge means) can be omitted. In such embodiments, rear wall frame  40  and front end frame  42  can be connected to floor frame  32 , roof frame  34 , and/or side wall frames  36 , 38  by threaded fasteners or other suitable means when container  10  is in the deployed state and stored against floor  12  when container  10  is in the collapsed state.  
      One or more lifting lugs  106  can be provided to facilitate deployment and collapsing of container  10  using a crane or other lifting mechanism (not shown). Such lifting lugs preferably would be attached to roof frame portion  34  using fasteners or welded connections but, alternatively, could be attached to other portions of framework  30  by any suitable means.  
      The detailed design of container  10  and framework  30  as illustrated in the drawings and discussed above is representative, but by no means limiting. One skilled in the art would recognize that that the detailed design for a particular collapsible container according to the present invention is a function of, among other factors, the size of and intended use for the container. One skilled in the art would know how to size and arrange the members (e.g., perimeter rims, joists, rafters, columns, stiffeners, braces, etc.) used to build the various frame portions, select appropriate materials (e.g., tube steel, angle iron, and steel channel) for such members, specify connection details (e.g., brackets, hinge mechanisms, etc.), and specify connection methods (i.e., bolting, welding, etc.).  
      With container  10  in the deployed state, as shown in  FIGS. 1 and 5 , upper and lower side walls  16 U, 18 U and  16 L, 18 L, respectively, are substantially perpendicular to floor  12  and roof  14  and coextensive with each other. Rear wall  20  and front end  22  are substantially perpendicular to floor  12 , roof  14 , and side walls  16 , 18 . Preferably, at least portions of the outer perimeter of each of rear wall frame  40  and front end frame  42  are at least loosely engaged with interior portions of roof frame  34  and side wall frames  36 , 38 , as best shown in  FIG. 5 , so as to inhibit collapse of roof  14  and side walls  16 , 18 .  
      In preferred embodiments, as best shown in  FIG. 6 , corresponding pairs of apertures  78  are provided in adjacent portions of roof frame  34 , upper and lower side wall frames  36 U, 38 U and  36 L, 38 L, respectively, rear wall frame  40  and front end frame  42  to enable use of fasteners, for example, bolts  80 , to interconnect such frame portions when container  10  is in the deployed state. (In practice, more or fewer pairs of apertures  78  than shown in  FIG. 6  may be provided.) For example, one or more bolts  80  preferably are inserted through corresponding pairs of apertures  78  in adjacent portions of the foregoing frame members to secure perimeter rim  48  of roof frame portion  34  to perimeter rim  58 U of upper side frame portions  36 U, 38 U, perimeter rim  86  of rear frame portion  40 , and perimeter rim  96  of front frame portion  42 . Similarly, one or more bolts  80  can be used to secure perimeter rim  56 U of upper side frame portions  36 U, 38 U to perimeter rim  56 L of lower side frame portions  36 L, 38 L (see  FIG. 6D ), and one or more bolts  80  can be used to secure perimeter rims  56 U, 56 L of upper and lower side frame portions  36 U, 36 L, 38 U, 38 L to perimeter rim  86  of rear frame portion  40  and perimeter rim  96  of front frame portion  42 .  
      Preferably, bolts  80  engage with captive nuts  82  associated with one aperture  78  of each of such corresponding pairs of apertures  78 . Loose nuts (not shown) can be used in lieu of captive nuts  82 , but captive nuts  82  are preferred because they are permanently affixed, for example, welded as bridge weld nuts, to framework  30  and thus do not contribute to the inventory of loose parts (including, e.g., certain bolts  80 ) that must be controlled when container  10  is in the collapsed state. Apertures  78  can be configured so that bolts  80  are inserted through members to be joined in their entirety. For example, as shown in  FIG. 5 , bolts  80  extend through the entirety of bottom member  60 U of upper side wall frame  38 U and top member  62 L of lower side wall frame  38 L and are fastened to captive nuts  82  (or a loose nut) on the bottom surface of top member  62 L of lower side wall frame  38 L. In embodiments where at least one of the members to be fastened together has a hollow cross-section (e.g., tube steel), captive nuts  82  preferably are fitted on the inside of such member so that bolt  80  need not extend through the entirety of such member. In all embodiments, bolt  80  preferably is installed into the members to be connected from the interior of container  10  to preclude tampering with bolt  80  from the exterior of container  10 .  
      Although threaded fasteners are preferred for the foregoing mechanical connections, various other forms of fasteners, including quick release fasteners, can be used in lieu of threaded fasteners in certain embodiments, as would be known to one skilled in the art.  
      Preferred embodiments also include a coupling associated with pairs of corresponding columns  64 U, 64 L of upper and lower side wall frames  36 U, 38 U and  36 L, 38 L, respectively, which helps to secure the upper and lower side wall frames  36 , 38  in the deployed position.  FIGS. 6, 6B , and  6 C illustrate one such embodiment wherein columns  64 U, 64 L are members, such as tube steel, having hollow cross sections and coupling  84  is a member, such as steel bar stock or tube steel, sized to fit within columns  64 U, 64 L in sliding engagement. Coupling  84  is movable between a first, retracted position, wherein coupling  84  is engaged with column  64 L, but not column  64 U, and a second, deployed position wherein coupling  84  is engaged with both column  64 L and column  64 U, thus inhibiting the collapse of upper and lower side wall frames  36 U, 38 U and  36 L, 38 L.  
      In preferred embodiments, coupling  84  includes a handle  85  that extends through slot  89  in column  64 L. Preferably, handle  85  is a bolt threaded into and staked to a threaded aperture  87  in coupling  84  (or a bolt inserted through an unthreaded aperture in coupling  84  and threaded into and staked to a captive nut attached to coupling  84 ) so that handle  85  cannot be inadvertently removed from coupling  85 . Slot  89  and handle  85  interact to define the extent to which coupling  84  can slide within columns  64 L, 64 U.  
      In preferred embodiments, coupling  84  includes a number of apertures  91  and corresponding captive nuts  83 , and columns  64 U, 64 L include a number of apertures  78  that align with apertures  91  in coupling  84  when coupling  84  is in the deployed position. Coupling  84  can be secured in the deployed position by inserting bolts  80  through apertures  78  in columns  64 U, 64 L and apertures  91  in coupling  84  and threading them into captive nuts  83 . Preferably, columns  64 U, 64 L also include a number of apertures  78  that align with apertures  91  in coupling  84  when coupling  84  is in the retracted position. Coupling  84  can be secured in the retracted position by inserting bolts  80  through such apertures  78  in columns  64 U, 64 L and apertures  91  in coupling  84  and threading them into captive nuts  83 . One skilled in the art would recognize that coupling  84  and the means for securing coupling  84  to columns  64 U, 64 L could be modified in many ways. For example, apertures  91  in coupling  84  could be threaded and captive nuts  83  could be omitted. Apertures could provided to allow bolts  80  to extend through columns  64 U, 64 L in their entirety and captive nuts could be provided with columns  64 U, 64 L to secure bolts  80  thereto. Alternatively, coupling  84  could be external to columns  64 U, 64 L.  
      With container  10  in the deployed state, door  26  can be readily moved between the retracted position, wherein door  26  nests within roof frame  34 , and the deployed position wherein door  26  closes the opening defined by front end  22 . Guide rollers  56  help door  26  transition between a substantially vertical orientation defined by door tracks  76  attached to front end frame  42  and a substantially horizontal orientation defined by door tracks  54  attached to roof frame  34 .  
      Roof skin  24 R preferably takes the form of a fiberglass shell overlying and connected to the exterior of roof frame  34 , as shown in the drawings. Side wall skin  24 SW and rear wall skin  24 RW preferably take the form of rigid or semi-rigid panels, preferably made of high molecular weight polyethylene, the edges of which are received by channels  108  associated with the members comprising at least portions of side wall frames  36 , 38  and rear wall frame  40 . Alternatively, skins  24 R, 24 SW, 24 RW can be made of any suitable rigid, semi-rigid, or flexible material and attached to the inside or outside of the corresponding frame portion using any suitable means, for example, adhesives, rivets, threaded fasteners, etc.  
      Preferably, one or more portions of side wall perimeter rim  58  and rear wall perimeter rim  86  are removable to allow replacement of sections of side wall skin  24 SW and rear wall skin  24 RW should they become damaged. For example, upper side wall frame  36 U preferably is configured so that top member  62  can be removed to allow replacement of corresponding side wall skin  24 SW by sliding such skin in and out of channels  108 . Preferably, top member  62  is attached to columns  64 U using brackets (not shown) that are riveted to one of top member  62  and columns  64 U and welded or otherwise attached to the other of top member  62  and columns  64 U. Alternatively, such brackets can be riveted to both of top member  62  and columns  64 U. Should side wall skin  24 SW need replacement, such rivets (not shown) could be easily drilled out and replaced. Rear wall frame  40  and corresponding skin  24 R can be similarly configured.  
      A preferred procedure for placing container  10  into the deployed state from the collapsed state involves attaching suitable rigging to lifting lugs  106  and a suitable lifting mechanism, for example, a crane or fork lift. The lifting mechanism then raises roof  14 , causing upper and lower side walls  16 U, 18 U, 16 L, 18 L to unfold from positions adjacent and substantially parallel to the bottom of roof  14  and top of floor  12 , respectively, to form substantially planar and vertical walls  16 , 18 . Couplings  84  are then moved from a retracted position within column  64 L to a deployed position within both of columns  64 L and  64 U. Bolts  80  are inserted through apertures  91  in coupling  84  and apertures  78  in corresponding portions of columns  64 L and  64 U and secured to captive nuts  83 . Rear wall frame  40  and front end frame  42  are then unfolded from positions adjacent and substantially parallel to the top of floor  12  to positions substantially perpendicular to each of floor  12 , roof  14 , and side walls  16 , 18 . As discussed above, stop plates  104  prevent over-rotation of rear wall frame  40  and front end frame  40  and help to index rear wall frame  40  and front end frame  40  to the desired orientation relative to  12 , roof  14 , and side walls  16 , 18 . Bolts  80  are inserted through corresponding pairs of apertures in the foregoing frame sections and fastened to captive nuts  82 . The rigging can be safely removed once couplings  84  have been deployed and secured, but preferably remains in place until the previous step has been completed. If container  10  includes foldable guide roller brackets  57 , such brackets are moved to the deployed position. Door  26  then can be moved between its open and closed positions, traveling over guide rollers  56 .  
      A preferred procedure for collapsing container  10  essentially reverses the steps of the foregoing deployment procedure. That is, door  26  typically would be placed in the stored position within roof frame  34  and guide roller brackets  57 , if foldable, then would be placed in the stored position. Next, bolts  80  would be removed from apertures  78 , except those apertures  78  through which bolts  80  are secured to couplings  84 . Next, rear wall frame  40  and front wall frame  42  would be folded against floor  12 . Bolts  80  securing rear wall frame  40  and front wall frame  42  to side wall frames  36 , 38  and roof frame  34  could then be reinstalled in the apertures  78  from which they were removed and threaded into captive nuts  82  to reduce the risk of losing such bolts  80 . Rigging would be installed before the next step, which involves loosening or removing bolts  80  securing couplings  84 , as necessary, to allow couplings  84  to be moved to the retracted position within the corresponding columns  64 L. Such bolts  80  then could be used to secure coupling  84  in the retracted position. Roof  14  then would be lowered by slackening the rigging connected to lifting lugs  106 . It may be necessary to exert an inward force near hinges  70  joining upper and lower side wall frames  16 U, 16 L and  18 U, 18 L to initiate the folding of walls  16 , 18 .  
      This disclosure illustrates and describes one or more particular embodiments preferred by the inventors. One skilled in the art would recognize that various modifications could be made to embodiment(s) disclosed herein without departing from the scope of the invention, which is limited only by the following claims.