Patent Publication Number: US-9834262-B2

Title: Aerodynamic rear drag reduction system for a trailer

Description:
This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 62/154,495 filed Apr. 29, 2015 entitled AERODYNAMIC REAR FAIRING SYSTEM FOR A TRAILER, the entirety of which is hereby incorporated by reference herein. 
     This application cross-references U.S. Pat. No. 9,199,673 issued Dec. 1, 2015 and titled AERODYNAMIC REAR DRAG REDUCTION SYSTEM FOR A TRAILER; U.S. application Ser. No. 14/928,056 filed Oct. 30, 2015 and titled AERODYNAMIC REAR DRAG REDUCTION SYSTEM FOR A TRAILER; U.S. application Ser. No. 14/709,980 filed May 12, 2015 and titled AERODYNAMIC REAR DRAG REDUCTION SYSTEM FOR A TRAILER; U.S. application Ser. No. 14/407,674 filed Dec. 12, 2014 and titled WAKE CONVERGENCE DEVICE FOR A VEHICLE; and U.S. application Ser. No. 15/044,220 filed Feb. 16, 2016 and titled AERODYNAMIC REAR DRAG REDUCTION SYSTEM FOR A TRAILER, the entirety of each of which is incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to an aerodynamic rear fairing or drag reduction system for reducing drag on a vehicle such as a van-type trailer or truck body, for example. 
     BACKGROUND OF THE INVENTION 
     To reduce wind flow resistance and drag on a trailer, truck, semitrailer, or other vehicle, side skirts which extend downwardly from a bottom of the trailer and/or chassis toward the roadway to partially enclose the floor assembly and undercarriage of the trailer, fairings and other such structures have been used. Many structures associated with the rear of the trailer are provided in order to also reduce the aerodynamic drag on the trailer. 
     A typical storage container of a trailer terminates with a large, rectangular rear surface. This shape causes an area of reduced pressure to be created behind the trailer storage container as it moves over the highway, thus generating a slowing force that must be overcome with additional engine power and thus additional fuel. In other words, turbulent air flow passing behind the vehicle imparts a drag force to the vehicle. Rear trailer fairings are designed to streamline the rear end of the trailer in order to control the flow of air at the rear of the vehicle. Such reduction on the drag of the ground vehicle may operate to conserve fossil fuels as well as other sources of vehicle drive power for hybrid vehicles, battery-operated vehicles, and alternative fuel-based vehicles, for example. However, many such fairings which extend from the rear end of the trailer also may cover the rear doors of the trailer which must be opened and closed by a user to load and unload the cargo within the storage area of the trailer in such a way that users may be required to dismount and mount, or otherwise manually operate, the fairing(s) each time a loading or unloading operation is to be performed. 
     SUMMARY 
     The present invention may comprise one or more of the features recited in the attached claims, and/or one or more of the following features and combinations thereof. 
     According to one aspect of the present disclosure, an aerodynamic rear drag reduction system is to be coupled to a rear frame assembly of a trailer including a rear frame and a rear swing door. The drag reduction system includes a side panel configured to be coupled to the rear swing door to extend generally vertically at least partially along a height of the trailer, and a folding mechanism coupled to the side panel to move the side panel between (i) a fully-deployed position wherein the side panel is configured to extend generally rearwardly away from the rear end of the trailer and (ii) a fully-stowed position wherein an inner surface of at least a portion of the side panel is configured to lie generally adjacent the rear swing door. The folding mechanism is configured to be coupled to a door locking mechanism of the trailer for movement therewith. 
     In one illustrative embodiment, the folding mechanism may be automatically actuated as a result of movement of the door locking mechanism. 
     In another illustrative embodiment, movement of a handle of the door locking mechanism from a locked position to an unlocked position may automatically moves the side panel form the fully-deployed position to the full-stowed position. 
     In yet another illustrative embodiment, the folding mechanism may be configured to be coupled to a lock-rod of the door locking mechanism. Further illustratively, rotational movement of the lock-rod may automatically actuate the folding mechanism. 
     In still another illustrative embodiment, the folding mechanism may include (i) a first linkage assembly configured to be coupled to a vertical lock-rod of a door locking mechanism, (ii) a vertically-extending deployment rod coupled to the first linkage assembly, and (iii) a second linkage assembly coupled at one end to the vertically-extending deployment rod and at another end to the side panel. Illustratively, the second linkage assembly may include (i) a first link coupled to the deployment rod for rotational movement therewith, and (ii) a second link pivotably coupled at a first end to the first link and pivotably coupled at a second end to the side panel. 
     In yet another illustrative embodiment, the aerodynamic rear drag reduction system may also include a top panel configured to be coupled to a top portion of the rear swing door of the trailer to extend generally horizontally at least partially along a top portion of the rear frame assembly of the trailer. Illustratively, the top panel may be movable between (i) a fully-deployed position wherein the top panel is configured to extend generally rearwardly away from the rear end of the trailer and a top edge of the side panel is spaced inwardly from an outer edge of the top panel and (ii) a fully-stowed position wherein the top panel is configured to lie generally adjacent to an outer surface of the side panel. Further illustratively, the folding mechanism may include a support arm engaged with a bottom surface of the top panel when the top panel is in the fully-deployed position. Further, the top panel may be positioned on top of the side panel and the bottom surface of the top panel may engages the outer surface of the side panel when the top and side panels are each in the fully-stowed positions. 
     According to another aspect of the present disclosure, an aerodynamic rear drag reduction system configured to be coupled to a rear frame assembly of a trailer including a rear frame and a rear swing door includes a top panel, a side panel, and a folding mechanism. The top panel is configured to be coupled to the rear swing door of the trailer to extend generally horizontally at least partially along a width of the trailer. The side panel is configured to be coupled to the rear swing door to extend generally vertically at least partially along a height of the trailer. The folding mechanism is directly engaged with the top panel and the side panel and configured to move the top and side panels between a fully-deployed position wherein the top and side panels are configured to extend generally rearwardly away from the rear end of the trailer and a fully-stowed position wherein the top and side panels are configured to lie generally adjacent the rear swing door. Illustratively, the top panel is supported by both the side panel and the folding mechanism when the top panel is in the fully-deployed position, and an outer surface of the side panel is spaced inwardly from an outer edge of the top panel when the top panel is in the fully-deployed position. 
     In one illustrative embodiment, a support arm of the folding mechanism may move along a bottom surface of the top panel as top panel moves between the fully-deployed and fully-stowed positions. 
     In another illustrative embodiment, the folding mechanism may include (i) a vertical deployment rod configured to be coupled to a vertical lock-rod of a door locking mechanism of the trailer for rotational movement with the lock-rod, and (ii) a linkage assembly coupled to the deployment rod and the side panel to move the side panel between the fully-deployed and fully-stowed positions. Illustratively, linkage assembly may include (i) a first link rigidly coupled at one end to the deployment rod for rotational movement therewith and (ii) a second link pivotably coupled at a first end to the distal end of the first link and pivotably coupled at a second end to the side panel. Further, the first link may extend generally rearwardly and the second link extends generally horizontally when the side panel is in the fully-deployed position. Illustratively, the second link may be configured to push against the side panel when the lock-rod is rotated in a counter-clockwise direction. The linkage assembly may also be configured to support the top panel thereon when the top panel is in the fully-deployed position. Illustratively, rotation of the lock-rod may cause rotation of the vertical deployment rod, and rotation of the vertical deployment rod urges the linkage assembly to move the side panel between the fully-stowed and fully-deployed positions. 
     In another illustrative embodiment, the aerodynamic rear drag reduction system may also include a limit strap coupled at one end to the side panel and configured to be coupled at another end to the rear frame assembly of the trailer. Illustratively, the limit strap may prevent the side panel from moving beyond a predetermined location when in the fully-deployed position. 
     In yet another illustrative embodiment, the aerodynamic rear drag reduction system may also include a bumper coupled to the side panel and configured to engage the linkage assembly when the side panel is in the fully-stowed position. Illustratively, the bumper may be configured to maintain a minimum angle between the side panel and the linkage assembly when the side panel is in the fully-stowed position. 
     According to still another aspect of the present disclosure, a method of operating a rear drag reduction system configured to be coupled to a rear frame assembly of a trailer including a rear frame and a rear swing door includes automatically moving a top panel of the rear drag reduction system and a side panel of the rear drag reduction system from a fully-deployed position wherein the top and side panels are configured to extend generally reawarwadly away from the rear end of the trailer to a fully-stowed position wherein the top and side panels are configured to lie generally adjacent the rear portion of the trailer upon movement of a door locking mechanism of the trailer from a locked position to an unlocked position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a rear perspective view of a rear end portion of a trailer showing a right and left aerodynamic rear drag reduction system of the present disclosure each in a fully-deployed position. 
         FIG. 2A  is a rear view of the drag reduction systems of  FIG. 1 , each including a side panel and a top panel coupled to the rear swing door of the trailer for movement therewith. 
         FIG. 2B  is an enlarged, rear view of the top panel and upper portion of the side panels of each drag reduction system shown in  FIGS. 1 and 2A . 
         FIG. 3A  is a side view of one of the drag reduction systems of  FIGS. 1, 2A , and  2 B. 
         FIG. 3B  is an exploded, perspective view of a portion of the side panel and showing an upper portion of a folding mechanisms including side linkage assemblies pivotably coupling the side panel to a vertical deployment rod actuated via movement of a door locking mechanisms of the trailer. 
         FIG. 4  is top view of the drag reduction systems of  FIGS. 1-3B  showing the top panels each including an upper/outer portion, a diagonal step, and a lower/inner portion, and showing the side panels (in phantom) positioned below and supporting the respective top panel thereon. 
         FIGS. 5A-8  are rear perspective views of one of the drag reduction systems of  FIGS. 1-4  moving from a fully-deployed position to a fully-stowed position by rotational movement of a lock-rod of the door locking mechanism of the trailer. 
         FIG. 5A  shows the drag reduction system in the fully-deployed position showing both the top panel and the side panel in fully-deployed positions. 
         FIG. 5B  is an enlarged, perspective view of the top panel and a portion of the side panel in the fully-deployed position, and showing the top panel supported on a top edge of the side panel as well as on a support arm including a roller at a distal end thereof. 
         FIG. 6  shows the lock-rod of the door locking mechanism of the trailer having been rotated in the counterclockwise direction toward an unlocked position (in order to allow a user to unlock the rear swing doors of the trailer) to similarly cause counterclockwise rotation of the vertical deployment rod that is coupled via a linkage assembly to the lock-rod in order to rotate the upper support arm as well as two other side linkage assemblies approximately 100 degrees from a first, rearwardly-extending, or deployed, position to a second, stowed or out-of-the-way position to move the side panel and the top panel to their fully-stowed positions. 
         FIG. 7  shows the side and top panels pivoting toward their fully-stowed positions as the support arm and side linkage assemblies continue to move toward their second position due to continued counterclockwise rotation of the lock-rod. 
         FIG. 8  shows the side and top panels in their fully-stowed positions with the side panel adjacent the rear swing door and the top panel folded over the side panel. 
         FIGS. 9-13  are rear and side perspective views of the drag reduction system of  FIGS. 1-8  showing the top and side panels in their fully-stowed positions against the rear swing door, and showing movement of the rear swing door toward its fully-opened position adjacent the sidewall of the trailer. 
         FIG. 9  is a rear perspective view of the trailer showing the drag reduction system in the fully-stowed position and showing the rear swing door of the trailer being moved toward a fully-opened position. 
         FIG. 10  is a rear perspective view of the trailer similar to  FIG. 9  showing the rear swing door moved further toward the fully-opened position. 
         FIG. 11  is a rear perspective view of the trailer similar to  FIGS. 9 and 10  showing the rear swing door moved still further toward the fully-opened position. 
         FIG. 12  is a side perspective view of the rear portion of the trailer of  FIGS. 9-11  showing the side panel and top panel moving with the rear swing door toward its fully-opened position. 
         FIG. 13  is a side perspective view of the rear portion of the trailer of  FIGS. 9-12  showing the rear swing door in the fully-opened position and the rear drag reduction system in its fully-stowed position located between the rear swing door and the sidewall of the trailer. 
         FIG. 14  is a perspective view of the horizontal, linkage assembly coupling the deployment rod to the lock-rod and showing a manual release mechanism of the linkage assembly. 
         FIG. 15  is an exploded, perspective view of the horizontal linkage assembly of  FIG. 14 . 
         FIGS. 16-18  are perspective, sectional views of the deployment rod, lock-rod, and the horizontal linkage assembly of  FIGS. 14 and 15  showing operation of the manual release mechanism to permit relative movement between a first and second link of the linkage assembly. 
         FIG. 16  is a perspective view showing a pull-tab of the manual release mechanism having been removed from within a slot of the second link. 
         FIG. 17  is a perspective view showing the second link moving to the right relative to the first link to rotate the deployment rod. 
         FIG. 18  is a perspective view showing the second link having moved all the way to the right relative to the first link in order to rotate the deployment rod and lower the top panel without having to rotate, or otherwise operate, the vertical lock-rod of the door locking mechanism. 
         FIG. 19A  is an exploded, perspective view of the upper, outer corner of the side panel showing a lock assembly coupled thereto. 
         FIG. 19B  is a perspective view of the lock assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to illustrative embodiments shown in the attached drawings and specific language will be used to describe the same. While the concepts of this disclosure are described in relation to a truck trailer, it will be understood that they are equally applicable to other vehicles generally, and more specifically to conventional flat-bed and/or box or van type trailers, examples of which include, but should not be limited to, straight truck bodies, small personal and/or commercial trailers and the like. Accordingly, those skilled in the art will appreciate that the present invention may be implemented in a number of different applications and embodiments and is not specifically limited in its application to the particular embodiments depicted herein. 
     Looking first to  FIG. 1 , a trailer  10  includes an aerodynamic rear drag reduction system  12  coupled to the rear frame assembly (including a rear frame  13  and rear doors  14  coupled to the rear frame  13 ) of the trailer  10 . Illustratively, the drag reduction system  12  operates to improve the aerodynamic efficiency of the trailer  10  by reducing drag and turbulent wind flow behind the rear end of the trailer  10 . In particular, the drag reduction system  12  operates to reduce turbulent airflow immediately behind the trailer  10  as the trailer  10  is traveling down the road. The turbulent airflow immediately behind the rear end of the trailer  10  is reduced because the drag reduction system  12  channels and controls the flow of air from the sides and top of the trailer  10  over the rear end of the trailer  10 . This reduction of turbulent airflow behind the trailer  10  may increase the fuel efficiency, or the efficiency of any other source of vehicle drive power, of the tractor/trailer combination. 
     Illustratively, the drag reduction system  12  extends behind the rear frame  13  and rear doors  14  of the trailer  10 . As is further discussed in additional detail below, the drag reduction system  12  is movable relative to the rear doors  14  of the trailer  10  between a fully-deployed, or use, position (shown in  FIG. 1 ), and a fully-closed, or stowed position (shown in  FIGS. 8 and 9-13 ). The drag reduction system  12  is also movable with the rear swing doors  14  of the trailer  10  when in the fully-stowed position as the doors  14  are moved to their fully-opened position shown I  FIG. 13 . As shown in  FIG. 1 , the trailer  10  includes a storage container  15  configured to carry cargo therein. The storage container  15  includes sidewalls  11 , a front end wall (not shown), the rear frame assembly (including the rear frame  13  and doors  14 ), a roof (not shown), and a floor assembly  24  which all cooperate together to define an inside storage portion of the container  15  that is able to store various articles or goods therein. The front end of the trailer  10  is configured to be coupled to a tractor (not shown) for towing the trailer  10  thereon, thus providing a tractor-trailer assembly. It should be understood that while the aerodynamic drag reduction system  12  is shown for use with a trailer  10 , the drag reduction system  12  may be coupled to any vehicle or storage container to reduce the drag thereon. 
     Illustratively, the trailer  10  includes two drag reduction systems  12 , as shown in  FIG. 1 . In particular, one system  12  is coupled to one rear swing door  14  of the trailer  10 , while the other system  12  is coupled to the other rear swing door  14  of the trailer  10 . For the purposes of the description herein, however, only the left drag reduction system  12  will be described herein. However, it should be understood that the two drag reduction systems  12  of the trailer  10  are identical in configuration and function. 
     As shown in  FIGS. 1-13 , the drag reduction system  12  includes a side panel  30  and a top panel  32 . As shown in  FIG. 1  and discussed in greater detail below, the side panel  30  is generally vertically-oriented and is hingedly coupled to the left rear swing door  14 . The top panel  32  is generally horizontally-oriented and is hingedly coupled to a top portion of the left rear swing door  14 . As is discussed in greater detail below, the top panel  32  is engaged with, and at least partially supported by, a top edge  54  of the side panel  30  when the rear drag reduction system  12  is in the fully-deployed position shown in  FIG. 1 . As is discussed in greater detail below, the drag reduction system  12  is configured to automatically move from the fully-deployed position shown in  FIG. 1  to the fully-stowed position shown in  FIGS. 8 and 9-13  when a user unlocks a door locking mechanism  200  of the trailer  10 . Once the drag reduction system  12  is in the fully-stowed positioned, a user may open the rear swing door  14  to its fully-opened position (shown in  FIG. 13 ) adjacent the side wall  11  of the trailer  10 . Further, the drag reduction system  12  is configured to automatically move from the fully-stowed position shown in  FIG. 8  to the fully-deployed position shown in  FIG. 1  (when the rear swing door  14  of the trailer  10  is in the closed position) when the user engages, or locks, the door locking mechanism  200  associated with the trailer  10 . As is further discussed herein, the rear drag reduction system  12  includes a manual override mechanism  139  which allows a user to manually move the rear drag reduction system  12  from its fully-deployed position to its fully-stowed position without unlocking or otherwise manipulating the door locking mechanism  200  of the trailer  10 . 
     As shown in  FIG. 3A , the side panel  30  extends along a height of the trailer  10 . Illustratively, a height of the side panel  30  is substantially the same as a height of the rear frame  13  of the trailer  10 . It should be understood, however, that the side panel  30  may be any suitable height greater than, equal to, or less than a height of the rear frame  13  and may be located at any position along a height of the rear frame  13  of the trailer  10 . Illustratively, an overall height  27  of the side panel  30  is approximately 111 inches while an overall width  21  of the side panel  30  is approximately 24 inches. Illustratively, the height  27  of the side panel  30  is measured a vertical distance between a highest point of the side panel  30  and a lowest portion of the side panel as shown in  FIG. 3A . The width  21  is measured as the greatest horizontal distance between the forward edge  52  and the rearward edge  50  of the side panel. 
     The side panel  30  includes a rearward edge  50 , a forward edge  52 , a top edge  54 , and a bottom edge  56 . Illustratively, the forward and rearward edges  52 ,  50  are generally vertical (and thus parallel to each other) while the top and bottom edges  54 ,  56  are angled relative to each other. The top edge  54  is angled downwardly from the forward edge  52  to the rear edge  50  while the bottom edge  56  is angled upwardly from the forward edge  52  to the rearward edge  50 , as shown in  FIG. 3A . The top angle is approximately 12 degrees to coincide with the downward angle  89  of the top panel  32  as is discussed in greater detail below. The top panel  32  is supported at least in part by the upper edge  54  of the side panel  30 ; as such, the upper edge  54  of the side panel  30  and the top panel  32  are configured to be similarly angled downwardly. The bottom edge  56  of the side panel  30  is illustratively angled upwardly from the forward edge  52  to the rearward edge  50 . Such an upward angle may assist in providing increased visibility for the bumper lights  99  of the trailer  10  to illuminate upwardly. It should be understood that while the top and bottom edges  54 ,  56  of the side panel  30  are both shown to be angled approximately 12 degrees, each of the top and bottom edges  54 ,  56  may be angled the same as or differently from one another and may be angled any suitable degree including an angle of zero degrees from a horizontal axis. Illustratively, both the forward edge  52  and the rearward edge  50  are located rearward of the rear end  60  of the trailer  10  when the rear drag reduction device  12  is in the fully-deployed position. As such, the entire side panel  30  is positioned rearward of the rear edge  60  of the trailer  10  when the side panel  30  is in the fully-deployed position. 
     Illustratively, the side panel  30  is angled inwardly by approximately 11 degrees from a plane parallel to the sidewall  11  of the trailer, as shown by the angle  91  in  FIG. 4 . As such, the side panel  30  is positioned inward of the outer edge  74  of the top panel  32  to allow the top panel  32  to rest on the upper edge  54  of the side panel  30  while a portion of the top panel  32  is positioned outwardly from a plane defined by the outer surface  67  of the side panel  30 . However, it should be understood that the side panel  30  may be generally parallel to the side wall  11  of the trailer, or may be angled by any suitable degree greater or lesser than that which is shown in  FIG. 4 . Further illustratively, the side panel  30  is not positioned to extend outwardly beyond a plane defined generally by the side wall  11  of the trailer  10  when the rear drag reduction system  12  is in the fully-deployed position. In other words, the side panel  30  is positioned inwardly of any plane defined by the side wall  11  of the trailer  10 . However, it is within the scope of this disclosure to position the side panel  30 , or any portion thereof, outwardly from the sidewall  11  when in the fully-deployed position as well. 
     As shown in  FIGS. 1, 3A, and 3B  the side panel  30  of the drag reduction system  12  is coupled to the rear swing door  14  via hinges  40 . Illustratively, three sets of hinges  40  are provided to couple the side panel  30  to the rear swing door  14 ; however, it should be understood that any suitable number of hinges may be provided. Each hinge  40  includes first hinge plate  41  coupled to the outer surface of the rear door  14 , a second hinge plate  44 , and a hinge joint  46  coupled to each of the first and second hinge plates  40 ,  41  to define a hinge axis  48  about which the side panel  30  is able to pivot when moving between the fully-deployed and fully-stowed positions. Illustratively, the first hinge plate  41  includes a portion  43  coupled directly to the door  14  via fasteners such as bolts, screws, rivets, and/or adhesive, for example, and an offset portion  45  which extends beyond an outer vertical edge of the door  14  to position the hinge joint  46  generally adjacent to the vertical member of the rear frame  13 . 
     Further illustratively, the forward edge  52  of the side panel  30  includes notches  53  formed therein. Illustratively five notches  53  are formed in the forward edge  52  to accommodate the hinges  61  of the door assembly which couple the rear swing door  14  to the rear frame  13  for pivoting movement about the frame  13  from the fully-closed position to a fully-opened position, such as that shown in  FIG. 13  for example. Thus, each notch  53  of the side panel  30  corresponds to and is positioned adjacent a respective hinge  61  of the door assembly of the trailer  10 . Illustratively, the hinge axis defined by the hinges  61  of the door  14  and the hinge axis  48  of the hinges  40  of connecting the side panel  30  to the door  14  are parallel to and spaced-apart from each other. In particular, the hinge axis  48  is positioned inwardly and forwardly from the hinge axis of the door hinges  61  to position the hinge axis  48  closer to the outer edge and outer surface  39  of the door  14 . 
     Illustratively, as shown in  FIG. 3B , the rearward edge  50  of the side panel  30  is folded, or hemmed, in order to stiffen the panel  30  and reduce any potential flapping or wobbling of the side panel  30  as the trailer  10  travels down the highway. Illustratively, this hemmed portion of the side panel  30  further defines a bend along a vertical axis thereof resulting in two different planar surfaces  23 ,  25  as shown in  FIGS. 3B and 4 . Illustratively, the second planar surface  25  is angled inwardly approximately 20 degrees from the first planar surface  23  in order to further direct the flow of air around and behind the trailer  10 . As shown in  FIG. 4 , the side panel  30  is positioned inwardly of the outer edge  74  of the top panel  32  such that an outer portion of the top panel  32  (located inside the outer edge  74  of the top panel) is positioned on and engaged with the top edge  54  of the side panel  30 . In particular, the top edge  54  of the side panel  30  is positioned inwardly, and spaced-apart from, of the outer edge  74  of the top panel  32 . It should be understood that while the illustrative side panel  30  includes the two planar surfaces  23 ,  25  angled approximately 20 degrees from each other, it is within the scope of this disclosure to provide a side panel having only a single planar surface as well as a side panel having two or more angled surfaces which are each positioned at any suitable angle relative to each other. 
     Looking now to  FIGS. 1, 2B, and 4 , the top panel  32  of the rear drag reduction system  12  extends generally horizontally along an upper, rear edge  19  of the rear frame  13 . In particular, the top panel  32  extends along and above the horizontal top edge of the rear swing door  14  of the trailer  10 . The top panel  32  is generally rectangular in shape and includes a forward edge  70 , a rearward edge  72 , an outer edge  74 , and an inner edge  76  as shown in  FIG. 4 . Illustratively, the outer edge  74  is longer than the inner edge  76 , and the forward edge  70  is longer than the rearward edge  72 . Further illustratively, the inner and outer edges  74 ,  76  are not parallel to each other while the forward and rearward edges  70 ,  72  are also not parallel to each other. 
     As shown in  FIG. 4 , the forward edge  70  generally extends horizontally and is parallel to the upper edge  19  of the rear frame  13 . The rearward edge  72 , angles forwardly from the outside edge  74  toward the inside edge  76 . As such, the inside edge  76  is shorter in length than the outside edge  74 . Illustratively, the outside edge  74  angles slightly inwardly from the forward edge  70  to the rearward edge  72 . Similarly, the inside edge  76  also angles slightly inwardly from the forward edge  70  to the rearward edge  72 . Illustratively, the rearward edge  72  is angled approximately 7 degrees from a plane parallel to the rear swing door  14 ; the outer edge  74  is angled approximately 5 degrees and the inside edge  76  is angled approximately 3 degrees from a plane perpendicular to the rear swing door  14  and parallel to the sidewall  11 . As shown in  FIG. 4 , the rearward edge  72  of the top panel  32  is positioned farther rearwardly than the rearward edge  50  of the side panel  30  when the rear drag reduction device is in its fully-deployed position. Illustratively, the top panel  32  extends approximately 35 inches rearwardly while the side panel  30  extends approximately 23 inches rearwardly when measured horizontally from the top member of the rear frame  13  of the trailer  10 . While the particular locations, lengths, and angles of the edges  70 ,  72 ,  74 ,  76  of the top panel  32  are shown and described herein, it should be understood that the edges  70 ,  72 ,  74 ,  76  may be oriented in any suitable manner and length to define the top panel  32 . 
     As shown in  FIGS. 1, 2A, and 2B , the top panel  32  includes an upper planar portion  80 , a step  82 , and a lower, or stepped-down, planar portion  84 . The upper portion  80  defines a plane that is positioned above a plane defined by the lower portion  84  of the top panel  32 . As shown in a plan view in  FIG. 4 , the step  82  extends somewhat diagonally at an angle across a width of the top portion  32  to define the upper generally triangular portion  80  and the lower generally quadrilateral portion  84 . In particular, the step  82  angles outwardly from the forward edge  70  to the rearward edge  72 , such that the upper portion  80  also defines an outer portion of the top panel  32  and the lower portion  84  also defines an inner portion of the top panel  32 . Illustratively, the step  82  does not define a vertical plane, but is angled as shown in  FIGS. 1 and 4 . As shown best in  FIG. 4 , the forward edge  70  of the lower portion  84  defines a curved cut-out  69 . The curved cut-out  69  provides clearance for the upper portions of the door locking mechanism  200 . 
     An angle  86  between the step  82  and the forward edge  70  of the lower portions  84  of the top panel  32  is approximately 135 degrees. As shown in  FIG. 2B , the stepped-down portion  84  of the top panel  30  is positioned above the top edge of the rear swing door  14  and below the upper, center identification lights  88  of the trailer  10 . As such, a driver traveling behind the trailer  10  of the present disclosure is able to see the identification lights  88  of the trailer  10  and the light emanated therefrom. Illustratively, the particular dimensions of the top panel  32  provide that a driver traveling behind the trailer  10  is able to see the identification lights  88  from a line of site approximately 10 degrees angled downwardly from the center, identification lights  88  and 45 degrees to the left and right of the lights  88 . While such a driver may be unable to see the center, top identification lights  88  at close distances between the driver and the rear end of the trailer  10 , the driver may then able to see the corner clearance lights  87  (shown in  FIG. 5B ) located at the upper corners of the rear frame  13  of the trailer  10  when the rear drag reduction system  12  is in the fully-deployed position. These upper corner lights  87  are positioned below the forward edge  72  of the upper portion  80  when the top panel  32  is in the fully-deployed position. As such, the two lower portions  84  of the adjacent top panels  32  create a viewable center ID light zone  85  defined by the angled steps  82  and the forward and rearward edges  70 ,  72  of the step-down portions  84  while also providing a top panel  82  having outer portions  80  with a forward edge  70  generally aligned with a top, rear edge  19  of the trailer  20  to maximize the aerodynamic effects of the top panel  32  on the trailer  10 . 
     As shown best in  FIGS. 1 and 3A , the entire top panel  32 , including the upper portion  80 , the step  82 , and the lower portion  84 , is angled downwardly from the forward edge  70  of the panel  32  to the rearward edge  72  of the panel  32 . The forward edge  70  of the panel  32  is approximately located at the same height as the rear edge  19  top of the rear frame  13  of the trailer  10  while the rearward edge  72  of the top panel  32  is positioned at a location generally below the top edge  19  of the rear frame  13  of the trailer  10 . Illustratively, the top panel  32  is angled downwardly approximately 12 degrees to define an acute angle  89  (shown in  FIG. 3A ) between the top panel  32  and the rear frame  13  of the trailer  10 . As discussed above, the top edge  54  of the side panel  30  is angled substantially the same 12 degrees to allow the top panel  32  to rest thereon. The upper portion  80  of the top panel  32  illustratively rests on the top edge  54  of the side panel as shown in  FIG. 4 . Illustratively, both the upper portion  80  and the lower portion  84  of the top panel  32  are angled downwardly approximately the same 12 degrees. As such, the upper portion  80  and the lower portion  84  are generally parallel to each other. It should be understood, however, that the top panel  32  as well as the top edge  54  of the side panel, may define any suitable angle relative to the rear frame  13  of the trailer  10 . Further, the upper and lower panels  80 ,  84  may be angled relative to (and not parallel to) each other to define different angles relative to the vertical plane of the trailer  10 . 
     As shown in  FIGS. 5A and 5B , the top panel  32  is pivotably coupled to the rear swing door  14  for movement relative to the rear swing door  14  between fully-deployed and fully-stowed positions. First and second hinges  90 ,  92  of the rear drag reduction system  12  are coupled to the top panel  32  and the rear swing door  14  to allow the top panel  32  to pivot relative to the rear swing door  14 . As shown in  FIG. 5B , the first, outer hinge  90  includes an L-shaped hinge plate  93  having a vertically-extending portion  95  that is coupled to the outer surface  39  of the rear swing door  14  adjacent a top edge thereof, and a rearwardly-extending portion  97  coupled to a top end of the vertical portion  95  and extending generally perpendicularly to the portion  95 . The hinge  90  further includes a hinge joint  96  coupled to the distal end of the rearwardly-extending portion  97  of the L-shaped hinge plate  93 , and a hinge plate  94  coupled to both the hinge joint  96  and the bottom surface  31  of the upper portion  80  of the top panel  32 . As shown in  FIGS. 4 and 5B , the hinge joint  96  defines a pivot axis  98  therethrough. As is discussed below, the pivot axis  98  is not parallel to the upper rear edge  19  of the rear frame  13 , but is offset (or angled) relatively thereto in order to allow for more compact folding of the rear drag reduction system  12  when in the fully-stowed position. 
     In particular, when the rear swing door  14  of the trailer  10  is in its fully-opened position adjacent the sidewall  11  of the trailer  10 , the rear swing door  14  is not parallel to the sidewall  11  of the trailer  10 . Rather, a generally “pie-shaped” space (when viewed from above) is created between the door  14  and the sidewall  11 . It is in this pie-shaped space that the rear drag reduction system  12  is located when in its fully-stowed position. However, because the top panel  32  must fold over the side panel  30  and the lock-rods  202  of the door locking mechanism  200 , the offset, or angled, hinge axis  98  operates to accommodate this structure to allow the rear drag reduction system  12  to be positioned within the pie-shaped space between the sidewall  11  of the trailer  10  and the rear swing door  14  in the fully-stowed position. 
     Similar to the first, outer hinge  90 , the second, inner hinge  92  includes the hinge plate  94  coupled to the bottom surface  31  of the upper portion  80  of the top panel  32 , the hinge joint  96 , and an L-shaped hinge plate  103  including the vertical portion  95  and a larger rearwardly-extending (or horizontal) portion  107 . Because the hinge joint  96  of each hinge  90 ,  92  is coupled to a rearward end of the respective horizontal portions  97 ,  107  of each L-shaped hinge plate  93 ,  103 , and because the horizontal portion  107  of the second hinge  92  is larger (and extends farther rearwardly) than the horizontal portion  97  of the first hinge  90 , the hinge joint  96  of the second hinge  92  is positioned farther rearwardly from the rear frame  13  of the trailer  10  than the hinge joint  96  of the first hinge  90 . Similar to the first hinge  90 , the second hinge  92  is positioned at a slight angle so that the hinge joints  96  of the first and second hinges  90 ,  92  are aligned to define the angled hinge axis  98 . As shown best in  FIG. 4 , the hinge axis  98  defined by the first and second hinges  90 ,  92  is angled outwardly approximately 5 degrees from the rear frame  13  of the trailer  10  as measured from the outer edge  74  of the top panel  32  to the inner edge  76  of the top panel  32 . 
     It should also be noted that the vertical portion  90  of each L-shaped hinge plate of the hinges  90 ,  92  extends upwardly above the top edge of the swing door  14  in order to generally align the forward edge  70  of the upper portion  80  of the top panel  32  with the top rear edge  19  of the rear frame  13  of the trailer  10 . As such, both the forward edge  70  of the upper and lower portions  80 ,  84  of the top panel  32  is positioned above the rear swing door  14  when the top panel  32  is in the fully-deployed position. Further, the forward edge  70  of the top panel  32  is positioned above the rear swing door  14  when the top panel  32  is in the fully-stowed position. 
     In order to move side panel  30  and the top panel  32  between the fully-deployed and fully-stowed positions, the rear drag reduction system  12  includes a folding mechanism  100  coupled to the side panel  30 , the top panel  32 , and the rear swing door  14 . The folding mechanism  100  operates to move the side and top panels  30 , 32  from the deployed position extending away from the trailer  10  (as shown in  FIGS. 5A and 5B ) to a collapsed, or folded and stowed, position generally adjacent to the rear surface  39  of the rear swing door  14  (as shown in  FIG. 8 ). The folding mechanism  100  is coupled to a door locking mechanism  200  of the trailer  10  to move therewith. As is discussed in greater detail below, the folding mechanism  100  operates to automatically move the side and top panels  30 ,  32  to the fully-stowed position when a user moves the door locking mechanism  200  to an unlocked position in preparation for opening the rear swing door  14 , for example. 
     Looking again to  FIG. 5A , the folding mechanism  100  includes a vertically-extending deployment rod  102  coupled to the rear swing door  14  of the trailer  10  via brackets  104 , and a first lever arm or bracket  106  (shown best in  FIGS. 16-18 ) coupled at one end to the deployment rod  102  for rotational movement with the deployment rod  102  about a vertical axis defined by the deployment rod  102 . A horizontally-extending linkage assembly  108  is pivotably coupled at a first end to the distal end of the lever arm  106  for rotation about a vertical pivot axis  107 , and is pivotably coupled at a second end to a vertical lock-rod  202  of the door locking mechanism  200  via a bracket  111  defining a vertical pivot axis  109  at a distal end thereof. 
     The folding mechanism  100  further includes a support arm  112  coupled to a top end of the deployment rod  102  for rotational movement therewith. The support arm  112  extends rearwardly away from the rear frame  13  of the trailer  10  when the rear drag reduction system  12  is in the fully-deployed position. A roller  113  of the support arm  112  is coupled to a distal end of the arm  112  to engage the bottom surface  31  of the lower portion  84  of the top panel  32 . As such, the roller  113  of the support arm  112  is engaged with and supports the bottom surface  31  of the bottom portion  84  of the top panel  32  when the system  12  is in the fully-deployed position. Illustratively, the roller  13  engages the bottom surface  31  of the lower portion  84  of the top panel  32 . As noted above, the bottom surface  31  of the upper portion  80  of the top panel  32  is engaged with and supported on the top edge  54  of the side panel  30 , as shown in  FIG. 5A , when the rear drag reduction device is in the fully-deployed position. As is discussed in greater detail below, rotation of the deployment rod  102  during operation of the folding mechanism  100  causes the support arm  112  and side panel  30  to rotate therewith to a position where the top panel  32  is not supported on either the side panel  30  or the support arm  112  and is caused to pivot downwardly about the axis  98  of the hinges  90 ,  92  to its stowed position. While the illustrative support arm  112  and roller  113  are shown and described herein, it should be understood that any similar arm, fin, or other structure may be coupled to the deployment rod  102  to rotate with the deployment rod  102  and aide in supporting the top panel  32  thereon when the top panel  32  is in the fully-deployed position. 
     Looking now to  FIGS. 14 and 15 , the horizontally-extending linkage assembly  108  includes a first link  120  including two identical plates  122  spaced-apart from each other via three threaded pins  124  and accompanying nuts  125 . The pins  124  are received through aligned apertures  127  of the plates  122 . Each plate  122  includes a linear portion  126  and a curved, or hooked, portion  128  defining a curve  130 . The pin  124  received through and coupled to the end of the curved portion  128  of each plate  122  is also coupled to the mounting bracket  111  rigidly attached to the lock-rod  202  of the door locking mechanism  200 . This pin  124  operates to define the vertical pivot axis  109 . 
     The linkage assembly  108  further includes a second link  132  coupled to and positioned between the upper and lower plates  122  of the first link  120 . The second link  132  is generally U-shaped in cross-section and includes generally identical upper and lower plates  134  and a back plate  136  coupled to and positioned between each of the upper and lower plates  134  to define a channel  137  therein. Each of the upper and lower plates  134  of the second link  132  includes an elongated slot  138  and an aperture  140 . Two of the pins  124  located through the linear portions  126  of the plates  122  of the first link  120  are received through the aligned, elongated slots  138  of the upper and lower plates  134  of the second link  132  in order to allow the second link  132  to slide laterally back and forth relative to the first link  120  along an axis defined by the slots  138  that is generally perpendicular to the vertical pivot axis  109 . A fourth pin  124  is received through the apertures  140  of the second link  132  in order to couple the second link  132  to the lever arm  106  of the folding mechanism  100 . As noted above, the lever arm  106  is rigidly coupled to the deployment rod  102  for rotational movement therewith. The fourth pin  124  pivotably coupling the lever arm  106  with the second link  132  defines the vertical pivot axis  107 . 
     A manual release mechanism  139  is coupled to both the first link  120 , the second link  132 , and the two pins  124  received through the linear portion  126  of the plates  122  of the first link  120 . The manual release mechanism  139  is positioned within the channel  137  of the second link  132 . As is discussed in greater detail below, the manual release mechanism  139  allows a user to functionally disengage the folding mechanism  100  from the door locking mechanism  200  of the trailer  10  to allow the user to manually fold the top and side panels  30  and  32  to their fully-stowed positions without unlocking the door locking mechanism  200 . The manual release mechanism  139  includes a manual release lever  141  and a coil spring  150 . An aperture  142  at one end of the manual release lever  141  receives one pin  124  therethrough while a slot  144  at the other end of the manual release lever  141  receives the other pin  124  therethrough. The slot  144  defines an axis perpendicular to the elongated slots  138  of the second link  132 . The coil spring  150  is coupled at one end to the second link  132  and at the other end to a spring mount aperture  152  of the manual release lever  141 . 
     The manual release lever  141  further includes a detent  154  normally received through a slot  156  formed in the back wall  136  of the second link  132 . The coil spring  150  operates to bias the detent  154  to a locked position within the slot  156 . The manual release lever  141  further includes a pull-tab  158  configured to be grasped by a user in order to pull the detent  154  rearwardly against the bias of the spring  150  out of the slot  156  to an unlocked position allowing the second link  132  to move relative to the first link  120 . The coil spring  150  is aligned with the aperture  142  of the manual release lever  141  such that the corresponding pin  124  is received therethrough. This pin  124  defines a pivot axis  129  about which the manual release mechanism  139  pivots. 
     While the illustrative spring  150  is a coil spring, it should be understood that any biasing mechanism may be used in order to normally bias the manual release lever  141  to a locked position with the detent  154  received within the slot  156 . As is discussed in greater detail below, the first and second links  120 ,  132  are normally in a locked position and do not move, or slide, laterally relative to each other. Rather, the links  120 ,  132  operate as a single unit during operation of the folding mechanism  100  to allow a user to manipulate the handle  204  of the door locking assembly  200  in order to automatically move the side and top panels  30 ,  32  between fully-deployed and fully-stowed positions. However, the manual release mechanism  139  is provided to allow a user to move the first and second links  120 ,  132  laterally relative to each other to rotate the deployment rod  102  and the lock-rod  202  relative to each other to move the side and top panels  30 ,  32  from the fully-deployed position to the fully-folded position while maintaining the rear swing door  14  in a locked position. 
     Looking now to  FIGS. 2A, 3B, and 5A , the folding mechanism  100  further includes three illustrative linkage assemblies  37 ,  42  coupled to the deployment rod  102  for movement therewith and coupled to the inside surface  65  of the side panel  30 . As is discussed in greater detail below, the linkage assemblies  37 ,  42  operate to move the side panel  30  from its fully-deployed position to its fully-stowed position via operation of the folding mechanism  100  coupled to the door locking assembly  200 . Illustratively, as shown in  FIG. 5A , the folding mechanism  100  includes the top linkage assembly  37  (which, as is discussed below, includes the support arm  112 ), a middle linkage assembly  42 , and a bottom linkage assembly  42 . Each of the two middle and bottom linkage assemblies  42  includes a first link  44  rigidly coupled to the deployment rod  102  for rotational movement with the deployment rod  102  about a vertical axis defined by the deployment rod  102 . As shown in  FIG. 5A , the first links  44  extend generally rearwardly away from the rear door  14  of the trailer  10  when the rear drag reduction mechanism  12  is in the fully-deployed position. 
     Each linkage assembly  42  further includes a second link  46  pivotably coupled at a first end  47  to a distal end  49  of the first link  44  and pivotably coupled at a second end  73  pivotably coupled to the second panel  30  for pivotably movement relative to both the first link  44  and the second panel  30 . In particular, each linkage assembly  42  includes a first L-shaped bracket  63  coupled to the distal end  49  of the first link  44  and including a slot  57  formed therethrough defining a longitudinal axis generally parallel to the first link  44 . A pivot pin  58  defining a pivot axis  60  is received through the slot  57  of the mounting bracket  63  and an aperture  62  formed in the first end  47  of the second link  46 . As such, the second link  46  is pivotable about the axis  60  relative to the first link  44  and is also movable along the longitudinal axis of the slot  63  relative to the first link  44 . Another mounting bracket  63  is coupled to the inner surface  65  of the side panel  30 , and a fastener  64  defining a pivot axis  66  is received through the slot  57  of the mounting bracket  63  (which extends generally perpendicular to the vertical, longitudinal axis of the side panel  30 ) and an aperture (not shown) through the second end  73  of the second link  46 . As such, the second link  46  is pivotable about the axis  66  relative to the side panel  30  and is also movable along the longitudinal axis of the slot  57  relative to the side panel  30 . 
     It should be understood that the slots  57  within the mounting brackets  63  to allow for longitudinal movement of each end  47 ,  73  of the second link  46  relative to the side panel  30  and the first link  44 . Such longitudinal movement may help accommodate manufacturing tolerances in order to allow for the components of the linkage assembly  42  to be more easily installed and/or to allow for the components to better move relative to each other from the fully-deployed position to the fully-stowed position in order to fold close against the rear door  14  of the trailer  10 , for example. It should be understood that either a slot or aperture may be provided at within the mounting brackets  63 . Further, it should be understood that the second link  46  itself may be provided with a slot, rather than an aperture, at each of the first and second ends thereof. Further, while the slots  57  are shown and disclosed herein, it should be understood that a resilient grommet may also be used in order to accommodate such aforementioned manufacturing tolerances. 
     Looking now to  FIG. 3B , the top linkage assembly  37  is similar to the middle and bottom linkage assemblies  42  described above. As such, like reference numerals are used to denote like components. In particular, the top linkage assembly  37  includes the second link  46 , a mounting bracket  63  coupled to the inner surface  65  of the side panel  30  and to the second end  55  of the second link  46 , and another mounting bracket  63  coupled to the first end  47  of the second link  46 . The linkage assembly  37  further includes the support arm  112  described above. In general, the support arm  112  operates in the same manner as the first link  44  to connect the second link  46  to the deployment rod  102 . As shown in  FIG. 3B , the mounting bracket  63  is coupled to the support arm  112  at a location between the roller  113  and the proximal end of the support arm  112  coupled to the deployment rod  102  for rotational movement therewith. 
     As is described in greater detail below, the linkage assemblies  37 ,  42  couple the folding mechanism  100  of the rear drag reduction device  12  to the side panel  30  in order to move the side panel  30  between its fully-deployed and fully-stowed positions. As noted above, the top panel  32 , which is supported on the roller  113  of the support arm  112  and on the top edge  54  of the side panel  30 , is also moved between the fully-deployed and fully-stowed positions by movement of the folding mechanism  100 . That is, as the side panel  30  and support arm  112  are caused to rotate with the deployment rod  102  toward their stowed positions, the top panel  32  is no longer supported thereon and is, therefore, urged to pivot downwardly about the axis  98 . 
     A bumper  51 , as shown in  FIG. 3B , is coupled to an inner surface  65  of the side panel  30  near the mounting brackets  63 . The illustrative bumper  51  is made of rubber, but may be made of any suitable resilient, compressible, or pliable material. The rubber bumper  51  is generally cylindrical in shape and is provided to engage the second link  46  when the rear drag reduction system  12  is in its fully-stowed position. The rubber bumper  51  provides some cushion or dampening, as well as positioning of the components, when the side panel  30  is in the fully-stowed position. For example, the rubber bumper  51  may aide in setting the position and spacing of the side panel  30  relative to the link  46  when the side panel  30  is in the fully-stowed position. In particular, when the side panel  30  is in the fully-stowed position, the bumper  51  maintains a minimum angle between the link  46  and the side panel  30  and prevents the link and panel  46 ,  30  from folding any further beyond the minimum angle. The minimum angle ensures that once force is applied to the side panel  30  (via the linkage assemblies  37 ,  42 ) to deploy the side panel  30  from its fully-stowed position to its fully-deployed position, the side panel  30  deploys out away from the rear swing door  14  rather than going over the center of the link  46  toward the rear door  14 . Further, the resilient nature of the bumper  51  allows the bumper to compress slightly to store energy which is returned to the link  46  during the first few degrees of actuation allowing the side panel  30  to deploy with less effort. 
     Looking now to  FIGS. 2A, 2B, 3B, and 5A , the rear drag reduction system  12  further includes a first cable  77  coupled at a first end to the bottom surface  31  of the lower portion  84  of the top panel  32 , and coupled at a second end to the bracket  63  of the middle linkage mechanism  42  that is coupled to the inner surface  65  of the side panel  30 . In particular, a clip on the end of the cable  77  is coupled to a bracket on the bottom surface  31  of the top panel  32 , and a clip on the other end of the cable  77  is coupled to the L-shaped bracket  63 . A second cable  79  extends between, and is coupled to, the bottom surface  31  of the lower portion  84  of the top panel  32  via a clip and bracket and is coupled to the other mounting bracket  63  of the middle linkage mechanism  42  coupled to the first link  44  via a clip. Illustratively, the cables  77 ,  79  operate to minimize or prevent any tendency for the top panel  32  to move upwardly when the rear drag reduction device  12  is in the fully-deployed position and the trailer  10  is traveling down the highway. In other words, the cables  77 ,  79  operate to stabilize the top panel  32  when in the fully-deployed position. However, the cables  77 ,  79  do not operate to support the top panel  32  in its fully-deployed position. 
     Another cable  78  of the rear drag reduction device  12  is provided. As shown in  FIGS. 5A and 5B , the cable  78  is coupled at a first end to the mounting bracket  63  of the top linkage assembly  42  coupled to the inner surface  65  of the side panel  30 . A clip at the second end of the cable  78  is coupled to the lower plate  95  of the hinge assembly  90 . Illustratively, the cable  78  operates to prevent the side panel  30  from pivoting outwardly about the hinge axis  48  beyond its fully-deployed position when the side panel  30  is moved from its folded, or fully-stowed, position to its fully-deployed position. In other words, the cable  78  operates as a limit strap to prevent pivoting movement of the side panel  30  beyond its predetermined, angled location relative to the rear door  14  and the sidewall  11  of the trailer in its fully-deployed position. 
     In use, the rear drag reduction system  12  is automatically moved from its fully-deployed position to its fully-stowed position by the action of a user unlocking the door locking mechanism  200  of the rear swing door  14  of the trailer  10  as shown in  FIGS. 5A-8 .  FIGS. 9-13  further illustrate the ability of the rear swing door  14  (with the rear drag reduction system  12  thereon) to be moved to its fully-opened position adjacent the sidewall  11  of the trailer  10  when the rear drag reduction system  12  is folded and in its fully-stowed position against outer surface  39  of the rear swing door  14 . In particular, the side and top panels  30 ,  32  of the rear drag reduction system  12  are automatically moved from their fully-deployed positions to their fully-stowed positions by action of a user unlocking the door locking mechanism  200  of the trailer  10  (as shown in  FIGS. 5A-8 ); the fully-stowed side panel  30  and the fully-stowed top panel  32  of the rear drag reduction system  12  are then automatically moved with the rear swing door  14  by action of a user opening the rear swing door  14  and pivoting the rear swing door  14  about its hinges  50  approximately 270 degrees to its fully-opened position adjacent the sidewall  11  of the trailer  10  (as shown in  FIGS. 9-13 ). When the rear door  14  is in its fully-opened position, the rear drag reduction device  12  is positioned between the sidewall  11  and the rear surface  39  of the door  14 . 
     Looking first to  FIGS. 5A-8 , the door locking mechanism  200  of the trailer  10  includes the lock-rod  202  extending generally the entire vertical length of the rear frame  13  and coupled to the rear swing door  14  for pivoting movement relative thereto. A handle assembly of the door locking mechanism  200  includes the handle  204  coupled to the lock-rod  202  and latch  206  is coupled to the rear door  14  to receive the handle  204  in a locked position. When the handle  204  is received within the latch  206 , the lock-rod  202  is in a locked position where top and bottom ends of the lock-rod  202  are received within lock-rod keepers  208  coupled to the rear frame  13  of the trailer  10  to prevent the door  14  from being opened. When the handle  204  is received within the latch  206 , the support arm  112  is in an extended position extending rearwardly to aide in supporting the top panel  32  of the rear drag reduction system  12  in the fully-deployed position (as shown in  FIGS. 5A and 5B ). The top panel  32  is also supported by the top edge  54  of the side panel  30 . Further, when the handle  204  is received within the latch  206 , first links  44  (along with the support arm  112  operating as the first links  44 ) are also in an extended, or deployed, position extending rearwardly to position the linkage assemblies  37 ,  42  (including the second links  46 ) in their deployed position to support the side panel  30  in its fully-deployed position. 
     As the handle  204  of the door locking mechanism  200  of the trailer  10  is removed from the latch  206  and rotated approximately 180 degrees, as shown by the arrow  201  in  FIG. 6 , the lock-rod  202  of the door locking mechanism  200  is also rotated approximately 180 degrees in a counterclockwise direction about the vertical axis defined by the lock-rod  202  itself. As noted above, the deployment rod  102  is coupled to the lock-rod  202  via the lever arm  106  and the horizontal linkage mechanism  108  for rotational movement with the lock-rod  202 . In other words, the deployment rod  102  is “slaved” to the lock-rod  202  such that as the lock-rod  202  is rotated via a user rotating the handle  204 , the deployment rod  102  is similarly rotated about the vertical axis defined by the deployment rod  102  itself. When the user rotates the handle  204  approximately 180 degrees (as shown in  FIGS. 5A-8 ), the lock-rod  202  rotates approximately 180 degrees in a counterclockwise direction while the deployment rod  102  is caused to rotate approximately 100 degrees in the same counterclockwise direction. 
     The support arm  112  and the first links  44  are each rigidly coupled to the deployment rod  102 . As such, the support arm  112  and the first links  44  each rotate about the pivot axis defined by the deployment rod  102  when the deployment rod  102  is urged to rotate. As shown in  FIGS. 5A-8 , as the deployment rod  102  rotates approximately 100 degrees, the support arm  112  and first links  44  also rotate approximately 100 degrees between their deployed and stowed positions. Illustratively, therefore, the support arm  112  and the first links  44  each pivot approximately 100 degrees from their rearwardly-extending deployed positions to an out-of-the-way, or stowed, position wherein a distal, roller end  113  of the support arm  112  and the distal end  49  of the first links  44  are each generally adjacent the rear swing door  14  of the trailer  10 . As shown in  FIGS. 7 and 8 , the second link  46  of the linkage assemblies  37 ,  42  is urged to pivot about both axes  60 ,  66  while urging the side panel  30  to pivot inwardly about the pivot axis  45 . In moving to this out-of-the-way position, the first links  44  and support arm  112  pull the respective second links  42  therewith to urge the second panel  30  pivot in a counter-clockwise direction about the pivot axis  48  to lie generally adjacent to the rear surface  39  of the door  14 . 
     In particular, the second panel  30  is moved via the linkage assemblies  37 ,  42  to pivot about the axis  45  to position the inner surface  65  of the side panel  30  generally adjacent the rear surface  39  of the door  14 . Generally simultaneously, movement of the side panel  30  to its stowed position adjacent the rear swing door  14 , and movement of the support arm  112  to its out-of-the-way position adjacent the rear swing door  14  allows the top panel  32  to pivot downwardly (via gravity) to its folded, fully-stowed position also generally adjacent to the rear swing door  14  of the trailer  10 . The roller  113  rolls along the bottom surface  31  of the top panel  32  to its out-of-the-way, or stowed, position while the top edge  54  of the side panel  30  also moves along the bottom surface  31  of the top panel  32  to its folded position due to rotational movement of the deployment rod  102  and respective linkage assemblies  37 ,  42  of the folding mechanism  100  as described above. As noted above, the top panel  32  is pivotably coupled to the rear swing door  14  by hinges  90 ,  92  to allow the top panel  32  to pivot relative to the rear swing door  14  about a slightly angled axis  98 . While the angled axis  98  is shown and described herein, it should be understood that the axis about which the top panel  32  pivots may be angled at any suitable degree, or may be horizontal such that the axis is generally parallel to the rear edge  19  of the trailer  10 . 
     As noted above, the side panel  30  and the top panel  32  automatically move to their fully-stowed, folded positions when a user unlocks the door locking mechanism  200  of the trailer  10  by rotating the handle  204  of the door locking mechanism  200  approximately 180 degrees. Illustratively, as shown in  FIGS. 5A-8 , the side panel  30  folds to position the inner surface  65  of the side panel  30  adjacent the rear surface  39  of the rear swing door  14  of the trailer  10 . During this time, the top panel  32  folds downwardly over the side panel  30  to position the side panel  30  between the top panel  32  and the rear swing door  14  of the trailer  10 . Illustratively, the bottom surface  31  of the top panel  32  is adjacent to and generally engaged with an upper portion of the outer surface  67  of the side panel  30  when the rear drag reduction device  12  is in the fully-stowed position. 
     Looking now to  FIGS. 9-13 , once the side and top panels  30 ,  32  are moved to their fully-stowed positions, the top and side panels  32 ,  30  may move together with the rear swing door  14  to its fully-opened position adjacent the sidewall  11  of the trailer. In particular, as the rear swing door  14  is opened and moved to its fully-opened position generally adjacent the sidewall  11  of the trailer  10  (whereby the rear swing door  14  is pivoted approximately 270 degrees), the top and side panels  32 ,  30  remain in their fully-stowed positions adjacent the outer surface  39  of the rear swing door  14 . In other words, when the rear swing door  14  is moved to its fully-opened position, the rear drag reduction system  12  does not generally move relative to the rear swing door  14  and remains in its fully-stowed position against the rear swing door  14 . 
     When the rear swing door  14  is in the fully-opened position, the top panel  32  of the rear drag reduction system  12  is positioned between the sidewall  11  of the trailer  10  and the side panel  30 , and the side panel  30  is positioned between the top panel  32  and the rear swing door  14 . Both the top and side panels  32 ,  30  of the rear drag reduction system  12  are located in an out-of-the-way position between the sidewall  11  and the rear swing door  14  of the trailer  10  as shown in  FIG. 13 . 
     To move the rear drag reduction system  12  from the fully-stowed position shown in  FIGS. 8  (when the door  14  is in its closed position) and  9 - 13  (when the door  14  is moved to its fully-opened position) to the fully-deployed position shown in  FIG. 1 , the user simply moves the rear swing door  14  to its closed position and moves the handle  204  of the door locking mechanism  200  to the locked position within the latch  206 . In other words, when the user moves the rear swing door  14  to its closed position and locks the handle  204  of the door locking mechanism  200 , the rear drag reduction system  12  is automatically moved to its fully-deployed position. In particular, as the rear swing door  14  is moved to its fully-closed position, the rear drag reduction system  12  remains in its fully-stowed position adjacent the rear surface  39  of the door  14 . Next, once the door  14  is fully-closed, as a user rotates the handle  204  of the door locking mechanism  200  to a locked position in order to lock the rear swing door  14  to the rear frame  13 , the deployment rod  102  is rotated in a clockwise direction to move the support arm  112  and the first links  44  to their rearwardly-extended deployed positions. As the support arm  112  moves from its stowed, out-of-the-way position adjacent the rear swing door  14  to its deployed position, the roller  113  of the support arm  112  moves along the bottom surface  31  of the top panel  32  to aide in raising the top panel  32  from its folded, unsupported position to its extended position supported at least in part on the roller  113  of the support arm  112 . 
     Further, as the first links  44  move from their stowed, out-of-the-way positions adjacent the rear swing door  14  to their rearwardly-extended deployed positions, the second links  46  are urged to pivot about the axes  60 ,  66  to urge the side panel  30  to pivot about the axis  45  to its fully-deployed position. As noted above, the cable  78  operates as a limit strap to prevent movement of the side panel  30  from the fully-stowed position to a position beyond the predetermined, angled fully-deployed position of the side panel  30 . As the side panel  30  pivots about the axis  45  to its fully-deployed position, the top edge  54  moves outwardly along the bottom surface  31  of the top panel  32  to raise the top panel  32  from its folded, unsupported position to its extend position supported on the top edge  54  of the side panel  32  and on the roller  113  of the support arm  112 . 
     As noted above, the rear drag reduction system  12  also includes a manual release mechanism  139  which allows a user to move the side and top panels  30 ,  32  from their fully-deployed positions to their fully-stowed positions without moving the door locking mechanism  200  itself to the unlocked position. For example, there may be occasions when a user wants to maintain the doors  14  of the trailer  10  in a locked position while also moving the rear drag reduction device  12  to the fully-stowed position in order to park the rear end of the trailer  10  in close proximity to another object, for example. As shown in  FIGS. 14-18 , the folding mechanism  100  may be functionally disengaged from (though still coupled to) the door locking mechanism  200  by moving the manual release lever  141  of the manual release mechanism  139  from its normally locked position to an unlocked position. 
     As shown in  FIG. 14 , for example, the manual release lever  141  is in its locked position such that the detent  154  is received with in the slot  156  of the second link  132  in order to cause the first and second links  120 ,  132  to move laterally in unison with each other as the lock-rod  202  of the door locking mechanism  200  is rotated. However, by pulling the tab  158  of the manual release lever  141  against the bias of the spring  150  away from the back wall  136  of the second link  132 , the manual release lever  141  is moved to an unlocked position whereby the detent  154  is removed from within the slot  156  of the second link  132  (as shown in  FIG. 16 ) to allow the second link  132  to move laterally relative to the first link  120 . As shown in  FIGS. 17 and 18 , once the manual release lever  141  is moved to the unlocked position shown in  FIG. 16  and the detent  154  is removed from within the slot  156 , a user may grab the side panel  30  and pivot the side panel  30  about the axis  45  toward the rear door  14  to move the first link  44  (and support arm  112 ) of the linkage assemblies  37 ,  42  and the deployment rod  102  approximately 100 degrees to cause the second link  132  to slide laterally toward the lock-rod  202  of the door locking mechanism  200  without moving the first link  120  or rotating the lock-rod  202 . Movement of the side panel  30  to the fully-stowed position including movement of the support arm  112  to its out-of-the-way position allows the top panel  32  to pivot downwardly to its folded and fully-stowed position. Thus, the side and top panels  30 ,  32  of the rear drag reduction system  12  are moved to their fully-deployed positions without the use of the door locking mechanism  200 . 
     Alternatively, a user may position the top and side panels  32  in their fully-folded position with the door locking mechanism  200  in its locked position by first rotating the handle  204  of the door locking mechanism  200  approximately 180 degrees in order to rotate the lock-rod  202  of the door locking mechanism  200  approximately 180 degrees to fold the side and top panels  30 ,  32  to their fully-folded position (as is discussed in  FIGS. 5A-8  above). If the user wants to maintain the side and top panels  30 ,  32  in their fully-folded positions while maintaining the doors  14  of the trailer  10  in a locked position, the user may pull the manual release lever  141  to the unlocked position whereby the detent  154  is removed from within the slot  156  of the second link  132  to allow the first and second links  120 ,  132  to move relative to each other. With the manual release lever  141  in the unlocked position, the user may then manually rotate the handle  204  back to its original, locked position in order to rotate the lock-rod  202  approximately 180 degrees in a clockwise direction toward the locked position without moving or otherwise manipulating the deployment rod  102  and top or side panels  30 ,  32 . In other words, the handle  204  may be moved back to the locked position while maintaining the top and side panels  30 ,  32  in their fully-folded positions. As such, the side and top panels  30 ,  32  are positioned in their fully-folded positions while the door locking mechanism  200  is in the locked position. 
     When the top and side panels  30 ,  32  are in their collapsed, of fully-stowed, positions and the manual release mechanism  139  is in the unlocked position shown in  FIG. 18  such that the second link  132  has been laterally moved toward the lock-rod  202  relative to the first link  120  which remained generally stationary, the manual release mechanism  139  will automatically return to its locked position upon activation by the user of the door locking mechanism  200  to the unlocked position. That is, as the handle  204  and the lock-rod  202  are rotated counterclockwise approximately 180 degrees to an unlocked position, the bracket  111  is rotated therewith thus pulling the first link  120  (and the manual release mechanism  139  coupled thereto) laterally relative to the second link  132  until the detent  154  of the manual release mechanism  139  is aligned with the slot  156  of the second link  132  and biased by the spring  150  to be received therein to once again position the manual release lever  141  in its locked position to prevent relative movement between the first and second links  120 ,  132 . Accordingly, when the user next locks the door locking mechanism  200 , as described in detail above, the deployment rod  102  of the folding mechanism  100  will be urged to rotate with the lock-rod  202  to move the support arm  112  to its rearwardly-extending position thus moving the top and side panels  30 ,  32  to their fully-deployed positions once again. 
     Looking now to  FIGS. 19A and 19B , in order to prevent vertical motion of the top panel  32  relative to the side panel  30 , a lock assembly  400  is provided. The lock assembly  400  provides a mechanical interlock between the side panel  30  and the top panel  32  and may be used in lieu of or in conjunction with the cables  77 ,  79 . In particular the lock assembly  400  includes a catch, or pin hook,  402  illustratively coupled to the outside surface  67  of the side panel  30  via fasteners  404  received through apertures  406  formed in an upper, outer portion of the side panel  30  near a notch formed in the upper edge  54  and the outer edge  50  of the side panel  30 . Illustratively, the catch  402  is bent such that once coupled to the outer surface  67  of the side panel  30 , the head  408  of the catch  402  is generally aligned with the upper edge  54  of the side panel  30 . Illustratively, the catch  402  may alternatively be coupled to the inside surface  65  of the side panel  30  and similarly bent to align the head  408  of the catch  402  with the upper edge  54  of the side panel  30 . As shown in  FIG. 19B , the head  408  of the catch  402  is also not generally positioned higher than the top edge  54  of the side panel  30 . The lock assembly  400  also includes a keeper (not shown) coupled to the bottom surface  31  of the top panel  32 . The keeper illustratively includes a portion spaced-apart from the bottom surface  31  of the top panel  32  and including a slot formed therein. In operation, as the side panel  30  and top panel  32  are moved from their fully-stowed positions to their fully-deployed positions, the head  408  of the catch  402  is slid into the slot of the keeper to position the head between the bottom surface  31  of the top panel  32  and the keeper to prevent upward movement of the top panel  32  relative to the side panel  30 . 
     Illustratively, as noted above, while securement cables  77 ,  79  are shown and described herein, it should be understood that the lock assembly  400  may be used with or without the cables  77 ,  79 . Illustratively, while the particular lock assembly  400  is described herein, it is within the scope of this disclosure for the rear drag reduction system  12  to include any suitable lock assembly to prevent upward movement of the top panel  32  relative to the side panel  30  when the panels  32 ,  30  are in their fully-deployed positions such as, but not limited to, the locking assemblies described and disclosed within U.S. patent Ser. No. 14/709,980 filed May 12, 2015 and titled AERODYNAMIC REAR DRAG REDUCTION SYSTEM FOR A TRAILER, the entirety of which is hereby incorporated herein. 
     As noted above, when the drag reduction system  12  is in the deployed position the swing doors  14  of the trailer  10  are closed. The top and side panels  32 ,  30  of each of the two drag reduction systems  12  extend outwardly from the rear frame  13  and rear swing doors  14  in order to direct and smooth air flow around the rear end of the trailer  10  as the trailer  10  travels down the highway, for example. When the trailer  10  is not traveling on the road and it is necessary for a user or operator to open the rear doors  14  of the trailer  10  in order to gain access to the storage area of the storage container  15 , the user need only unlock and open the doors  14  in the usual or typical manner and the drag reduction system  12  coupled to each door  14  automatically moves to its stowed position. 
     Further, in order to move the drag reduction system  12  to the deployed position, the user need only close and lock the rear doors  14  and the system  12  coupled to each door  14  automatically moves to its deployed position upon movement of the door locking mechanism  200  to the locked position. In other words, it is not necessary to perform an extra step to move the drag reduction system  12  to the closed position prior to opening the trailer doors  14  or to move the drag reduction system  12  to the opened position after closing the doors  14 . Rather, the drag reduction system  12  automatically moves to the fully-stowed position upon unlocking the door  14  to which the drag reduction system  12  is attached, and automatically moves to the fully-deployed position upon locking the door  14  to which the drag reduction system  12  is attached. It should be understood that the drag reduction systems  12  of the present disclosure may be used alone or in conjunction with other drag reduction systems such as, for example, aerodynamic side skirts such as those disclosed in U.S. Pat. No. 8,177,286 and U.S. Pat. No. 8,783,758, for example, the entirety of each of which is incorporated herein by reference. 
     It should be understood that while the particular folding mechanism  100  is shown and described herein, alternative folding mechanisms such as those shown and described in U.S. patent application Ser. No. 15/044,220 may be provided as well. In fact, it should be understood that while the illustrative folding mechanism  100  of the present disclosure is shown and described herein in order to “slave” the actuation or movement of the side and top panels  30 ,  32  disclosed herein to the movement of the door locking mechanism  200 , it is within the scope of this disclosure to provide any suitable configuration of linkage type mechanisms between the lock-rod  202  and the side and top panels  30 ,  32  to translate the rotational motion of the lock-rod  202  of the door locking mechanism  200  to movement of the side and top panels  30 ,  32  between fully-deployed and fully-folded positions. In other words, it should be understood that the rear drag reduction system  12  includes any suitable folding mechanism coupled to the door locking mechanism  200  of the trailer  10  to automatically actuate and move the side and top panels  30 ,  32  of the rear drag reduction system  12  between fully-deployed and fully-folded positions via movement of the lock-rod  202  of the door locking mechanism  200 . It should also be understood that movement of the top panel  32  of the rear the rear drag reduction system  12  between the fully-deployed and fully-stowed positions may be accomplished solely via movement of the side panel  30  between its fully-deployed and fully-stowed positions or solely via movement of the support roller  113  on the support arm  112 . In other words, only one of these supporting components upon which the top panel  32  is supported are necessary to move the top panel  32  between its fully-deployed and fully-stowed positions. 
     Illustratively, each wall panel  30 ,  32  is made of a composite material. For example, the composite material may include a plastic core and metal outer skins coupled to the plastic core. Such a composite material provides a rigid, but lightweight and durable material. Illustratively, for example, each wall panel  30 ,  32  may be made of a DURAPLATE® composite panel provided by Wabash National Corporation of Lafayette, Ind. DURAPLATE® composite panels are constructed of a high-density polyethylene plastic core bonded between two high-strength steel skins. 
     The inner and outer skins respectively may be formed of a metal or metallic composition, examples of which include, but should not be limited to aluminum, galvanized steel, full hardened steel, such as AISI Grade E steel, or the like. In one illustrative embodiment, for example, the outer skin is formed of ASTM G90 galvanized steel, and the inner skin is formed of ASTM G40 galvanized steel. In alternative embodiments, the inner and/or outer skins respective may be formed of other rigid, semi-rigid, metallic or non-metallic materials. Illustratively, the composite material (i.e., panels  30 ,  32 ) is approximately between 0.08 inch and 0.20 inch thick, with a preferred thickness of approximately 0.10 inch thick. While the illustrative panels  30 ,  32  disclosed herein are each made of the particular composite material described above, it should be understood that other suitable composite materials may be used as well. For example, the panels  30 ,  32  may also be made from a plastic pultrusion with fiber reinforcements embedded inside the polymer material. The reinforcement fibers may be made from glass, carbon, and/or other suitable materials, for example. 
     It should be further understood that while the illustrative panels  30 ,  32  disclosed herein are made from a composite, the panels  30 ,  32  may alternatively be formed from a non-composite material such as a sheet made from a metal, metal alloy, or plastic, for example. The panels  30 ,  32  may be made from ferrous or nonferrous materials including plastics or composites incorporating a combination of ferrous and/or nonferrous materials thereof. In particular, an alternative panel (not shown) may be made from galvanized steel. Of course, it is within the scope of this disclosure to include non-galvanized steel sheets, or other such non-composite panels, of any suitable thickness as well. 
     While the invention has been illustrated and described in detail in the foregoing drawings and description, the same is to be considered as illustrative and not restrictive in character, it being understood that only illustrative embodiments thereof have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. In particular, it should be understood that the while certain illustrative top panels are disclosed herein, the rear drag reduction system of the present disclosure may include any suitable top and side panel configured to move between a fully-deployed and a fully-folded position. Further, the rear drag reduction system of the present disclosure may include any suitable folding mechanism coupled to the door locking mechanism  200  of the trailer  10  to automatically move the side and top panels between the fully-deployed and fully-stowed positions. Finally, the folding mechanism of the present disclosure may include any suitable manual release mechanism to functionally uncouple the folding mechanism from the door locking mechanism of the trailer  10 .