Abstract:
The volume capacity of a hook lift or roll-off truck container body is increased temporarily by vertical extension of the container body&#39;s walls and rear door. The extension includes three walls and another door which are firmly attached to the top edges of the container body&#39;s walls and doors. The extension is conveniently secured to the body and the doors of the body and the extension open and latch in concert.

Description:
BACKGROUND OF INVENTION 
     This invention relates to the class of article known as receptacles, more specifically to articles designed for removable attachment to an existing receptacle so as to enlarge the capacity of the existing, receptacle. This invention relates still more specifically to enlarging the volume capacity of open-top containers used to transport dry materials by truck, by extending the container walls in a vertical direction. These types of containers are known in the industry as roll-off and hook lift container bodies because they are configured to be picked up by, dumped, and removed from trucks having so-called roll-off and hook lift beds. The contents of the container bodies typically may be dumped by opening a rear door on the container body and elevating the front of the truck bed so as to tilt the container body rearward. 
     SUMMARY OF INVENTION 
     The present invention includes an apparatus for temporarily increasing the capacity of a truck container body by extending its vertical walls upward. It also includes the combined extension and container body. To be useful, such extension must preserve the ability to dump the container body by fully opening at the rear. The rear wall of the apparatus is hinged for opening and is fixed to the rear door of the container body so that both open cooperatively. 
     Roll-off and hook lift container bodies typically are manufactured in various capacities, such as 20 cubic yard and 40 cubic yard, and they are purchased by material haulers in one or more of these size to satisfy their own or their customers&#39; needs. For example, a waste management company might lease either 20 or 40 cubic yard container bodies to construction companies to contain refuse according the amount of refuse generated and the space available for the container body on the construction site. Because the smaller container bodies cost less than the larger ones and take up less space on site, the waste management company tries to keep in inventory the proper mix of capacities to satisfy all customers&#39; needs while minimizing the investment in container bodies. This invention provides an apparatus that creates more flexibility in inventory by allowing smaller container bodies to be converted temporarily to larger capacity when larger container bodies are not available, but at a lesser cost than a complete larger container body. 
     Objects of this invention are a) to provide an extension that may be removably attached to the top edge of a container body to increase its volume capacity; b) to increase the capacity at less cost than buying an entire larger container body, c) to enable one person to attach and detach the extension from the container body; d) to allow the dump door on the container body to continue to operate normally and in concert with the extension; and e) to enable extension apparatuses to be stacked one on top of the other in storage. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 depicts a prior art container body shown in perspective view from its upper left rear. 
     FIG. 2 is a perspective view of the extension from the upper left rear with the rear door closed. 
     FIG. 3 is a perspective view of the extension from the lower left rear. 
     FIG. 4 is the extension with its rear door partially open. 
     FIG. 5 is an upper left rear perspective view of the extension attached to a container body with the doors closed. 
     FIG. 6 is a detail perspective view of the joined door latch mechanisms of the extension and container body. 
    
    
     DETAILED DESCRIPTION 
     Referring now to in greater detail to the figures, in which like reference numerals depict like features in each figure, FIG. 1 depicts a typical prior art hook lift container body  1  shown in perspective view from its upper left rear. (“Rear” in these drawings means as seen from the rear of a vehicle carrying the container body.) The container body comprises a right vertical wall  2 , a left vertical wall  3 , a front wall  4 , a sloped bottom  5 , and a rear door  6 , which together form an open-topped box of substantially rectangular shape. Atop the walls are a right sill  7 , a left sill  8 , a front sill  9 , and a door sill  10 . Door  6  is swingably attached at a first vertical edge  101  to right wall  2  by hinges  11 . 
     Door  6  must by held closed tightly in transit and readily opened for dumping. Door  6  is closed and latched by latch assembly  12 , which comprises two latches, an upper latch  13  and a lower latch  14 , rotatably fixed to the outside of left wall  3  near the wall&#39;s rear edge. The latch assembly further comprises a striker notch  15 , an arm  16  connecting the two latches  13  and  14 , an a handle  17  on lower latch  14 . When door  6  is closed, the latches tightly hold upper door pin  18  and lower door, pin  19  on the second vertical edge  102  of door  6 . A middle door pin  20  rests in striker notch  15 . (See detail view in FIG. 6.) 
     Door  6  is opened by manually pulling upward on handle  17 , causing latches  13  and  14  to rotate clockwise (in this view) releasing door pins  18  and  19  respectively and allowing door  6  to open rearwardly. The door is closed again by manually pushing door  6  until middle pin  20  hits and seats in striker notch  15 , which serves to assure proper alignment of the door before latching. Handle  17  is then pushed down to rotate latches  13  and  14  into engagement with door pins  18  and  19 . Usually, such container bodies comprise means (not shown) for locking handle  17  in the down or up position to assure positive closure or release, respectively. 
     FIG. 2 is a perspective view of the extension  21  from the upper left rear. It comprises a right wall  22 , left wall  23 , front wall  24 , and rear door  25 , the door  25  shown in the closed position. These parts define a rectangular space having an open top and bottom. Door  25  is attached swingably at third vertical edge  222  to right wall  22  by hinges  221 . Door  25  is closed and latched by latch assembly  26  (similar to that of the container body of FIG. 1) which comprises an upper latch  27 , a lower latch  28 , a striker notch  29 , and an arm  210  connecting the two latches  27  and  28 . Latches  27  and  28  engage upper pin  211  and lower pin  212  on a fourth vertical edge  223  of door  25 , and striker notch  29  engages a middle pin  213  so as to align the door upon closing. An elongate connector  214  is rotatably attached at one end to lower latch  28 . The lower edges of the walls  22 ,  23  and  24  have a rigid flange  215  welded to them and extending horizontally outward from them. Depending vertically from the walls  22 ,  23 , and  24  and from door  25  (and only partially visible in this view) are guide strips  216 ,  217 ,  218  and  219  respectively. Also depending from the bottom edge of the rear end of left wall  23  and spaced outwardly from guide strip  217  is locating tab  220 . Similar locating tabs, not seen in this view but illustrated in FIG. 3, depend from the bottom edge of the rear end of right wall  22  and the from the center of the bottom edge of front wall  24 . 
     The extension  21  functions to increase the volumetric capacity of the container body  1  of FIG. 1 when it is placed on top of it so that flange  215  rests directly on sills  7 ,  8  and  9  of FIG.  1 . Satisfactory alignment of the flange and the sills is assured when guide strips  216 ,  217  and  218  are positioned inside walls  2 ,  3 , and  4  respectively. Guide strip  219  is positioned inside door  25 . 
     FIG. 3 is a perspective view of the extension  21  from the lower left rear to better show the guide strips and locating tabs. Again note locating tab  220  depending from left wall  23  and spaced outwardly from guide strip  217 . Depending from right wall  22  and front wall  24  and spaced outwardly from guide strips  216  and  218  respectively are right locating tab  31  and front locating tab  32 . The function of these locating tabs and guide strips is to assist in centering the bottom flange  215  of the extension directly on top of the sills of the container body, and to prevent lateral or longitudinal movement of the extension with respect to the container body during use. The tabs are spaced outwardly from their respective guide strips just enough to accommodate the container body sills, thereby acting as sill centering means  36  when the extension  21  is lowered into place (see FIG.  5 ). 
     To aid in connecting door  25  with door  6  on the prior art container body (see also FIGS. 5 and 6) a retainer tab  33  is provided rotatably connected to door  25  by bolt  34  and kept from swinging downward until needed by pin  35  protruding from door  25 . 
     FIG. 4 is the extension with its rear door partially open. Note that latches  27  and  28  are rotated in a clockwise direction compared with their positions in FIG. 2 so as to release upper and lower door pins  211  and  12  respectively and allow middle door pin  213  to move away from striker notch  29 . 
     FIG. 5 is an upper left rear perspective view of the extension  21  attached to the container body  1 . To attach the two so that they operate as a single container, it is necessary to attach the lower end of elongate connector  214  to the front portion of latch  13 , thereby forcing all four door latches to operate in concert when handle  17  is pulled upward. (See also detail in FIG. 6.) Further, it is necessary to fasten the entire extension  21  down onto the container body  1  to assure they stay together in use. One way to do this is to provide attachment eyes  52  and  53  on the sides of the container body I and the extension  21  respectively, connect the ends of a ratcheting turnbuckle  51  to eyes  52  and  53 , and tighten. (This turnbuckle assembly is shown on the left side of the extension in FIG.  5  and is duplicated out of view on the right side.) For convenience and protection against theft, the turnbuckle  51  may be permanently flexibly attached to the extension, for example, by means of a welded link to eye  53 . An easy means of attachment like a turnbuckle or come-along is preferred to simplify binding the extension to the container body, but other secure means of attachment may be used in combination with the extension and container body and are considered within the scope of this invention without limitation. The upper and lower ends of the attachment means may alternatively be affixed to the extension and container body by eyes and bolts, pins or keys secured through holes drilled in the extension and container body. Such alternative fastening means are considered within the scope of this invention without limitation. The final step in attaching the extension to the container body is to rotate retainer tab  33  counterclockwise about bolt  34  from its position in FIG. 3 into a vertical direction extending below the edge of door sill  10 . This traps the sill  10  of door  6  between retainer tab  33  and guide strip  219  on door  25 . (Only the extreme left end of guide strip  219  is visible in this view.) Thus confined, door  6  can only open in concert with door  25 . Other means of fastening the doors together temporarily, such as by a sliding bolt on door  25  and a keeper in door  6 , are to be considered within the scope of this invention without limitation. 
     FIG. 6 is a detail perspective view of the joined door latch mechanisms of the extension and container body, showing how the container body latch assembly (reference  12  in FIG. 1) and the extension latch assembly (reference  26  in FIG. 2) are connected after the extension is positioned on the container body. Latches  13  and  28  are connected to other latches (not shown) by arms  16  and  210 , respectively. Arms  16  and  210  are fastened to latches  13  and  28  by fasteners  66  and  65 , respectively. The fasteners allow rotation of the latches relative to the arms in a vertical plane, so that when the arms are moved upwardly or downwardly by an external force, the latches rotate clockwise or counterclockwise, respectively, about pivots  61  and  62 . For all latches to operate cooperatively, it is necessary to connect latch  28  to latch  13  by means of elongate connector  214 . To enable rapid connection of elongate connector  214  to latch  13 , fastener  66  may take the for of a snap or keyed pin rather than a bolt. Such other types of fasteners are considered within the scope of the present invention without limitation. The clockwise rotation of all of the now-interconnected latches (caused by lifting handle  17  in FIG. 5) in turn causes hooks  64  and  67  to move downward, releasing necks  63  and  68  of pins  212  and  18  respectively, and allowing connected doors  25  and  6  to open. 
     Note also in FIG. 6 the detail of striker notch  29  embracing neck  69  of pin  213 . Additionally, FIG. 6 shows detail of retainer tab  33  depending rotatably from bolt  34 , trapping sill  10  of door  6  between retainer tab  33  and guide strip  219  (hidden) on the lower edge of door  25 . Pin  35  holds tab  33  out of the way when tab  33  is rotated clockwise from the vertical to the horizontal when the extension is removed from the container body. In a similar fashion, elongate connector  214  may be rotated clockwise about fastener  65  for stowage by means of a bungee cord or the like (not shown) when the extension is removed from the container body.