Patent Publication Number: US-2015082704-A1

Title: Roll-up door seal

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 14/012,077, filed Aug. 28, 2013 and entitled SEAL WITH PRIMARY AND SECONDARY SEALING LOBES FOR USE IN ROLL-UP DOOR APPLICATIONS, which claims the benefit under Title 35, U.S.C. Section 119(e) of U.S. Provisional Patent Application Serial No. 61/779,336, filed Mar. 13, 2013 and entitled ROLL-UP DOOR SEAL and U.S. Provisional Patent Application Serial No. 61/697,937, filed Sep. 7, 2012 and entitled ROLL-UP DOOR SEAL, the entire disclosures of which are hereby expressly incorporated herein by reference. This application claims the benefit under Title 35, U.S.C. §119(e) of U.S. Provisional Patent Application Serial No. 61/884,185, filed on Sep. 30, 2013 and entitled ROLL-UP DOOR SEAL, the entire disclosure of which is hereby expressly incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to seals, and in particular, to seals that are adapted to seal roll-up type doors, such as cargo vehicle doors, garage and cargo bay doors, etc. 
     2. Description of the Related Art 
     Cargo trucks are sometimes provided with “roll-up” type cargo doors which raise and lower to selectively provide access to the cargo space of the truck. Such roll-up doors typically include a series of horizontal door panels hingedly connected to one another such that each panel is pivotable with the respect to the next adjacent panel about a horizontal hinge axis. As the roll-up door is raised, the panels progressively shift from a vertical orientation to a substantially horizontal orientation as the panels move inwardly away from the top of the door frame. To facilitate this function, rollers attached to the roll-up door typically ride within tracks disposed at each side of the door frame, with the tracks running vertically along the sides of the door frame and curving away from the top of the door frame to extend inwardly. 
     Seals may be provided along either side of roll-up door assemblies to inhibit ingress of water, smoke, particulates, or the like into the cargo space when the roll-up door is closed. In some cases, such seals are affixed to the door frame via fasteners, which may be coupled directly to the body of the seal or to a frame structure built around the seal. These seal arrangements hold a flexible portion of the seal against the outer surface of the roll-up door when the door is in a closed position. 
     Other roll-up door seals utilize specially designed door frames which accommodate custom-made, correspondingly shaped seal structures. These special seals may fit within the specially designed door frame structure to retain the seal at a desired position and orientation, but are not compatible with standard roll-up door frames or with other custom door frames. 
     Still other seals utilize multi-density cross-sectional profiles, including a relatively high density seal portion that can be press fit into a seal receiving area of a frame, and a lower density seal portion that is more flexible and bear against the roll-up door when the door is in the closed position. Such seals are typically made from polyvinyl chloride (PVC) with differing durometer values among the different seal portions. 
     While known roll-up door seals may be effective, it is desirable to minimize the cost and complexity of a roll-up door seal design, while also providing a reliable, long-lasting and fluid-tight seal between the roll-up door and the surrounding environment. 
     SUMMARY 
     The present disclosure provides a roll-up door seal arrangement including side seals, an upper seal and a lower seal to completely seal the periphery of a roll-up door when the door is in a closed position. The seals are sized and adapted to assemble to a standard roll-up door frame without a separate or dedicated frame structure. The seals provide redundant sealing surfaces, positioned to cooperate with both the door and door frame, which ensure an effective and durable fluid tight seal between the cargo space enclosed by the roll-up door and the ambient environment. The seal may be produced by extrusion from a flexible, weather resistant material such as EPDM, thereby providing a low cost solution for sealing roll-up doors having industry standard door frame constructions. 
     In one form thereof, the present disclosure provides a sealing system for sealing a perimeter of a roll-up door and door frame, the sealing system comprising: a top seal comprising: a coupling portion comprising an upper bridge, an inner leg forming a junction with the upper bridge, and an outer leg forming a junction with the upper bridge opposite the inner leg, such that the inner leg, the outer leg and the upper bridge define a U-shaped door receiving space with an open lower end; an upper sealing lobe extending laterally and upwardly away from the outer leg; and a lower sealing lobe forming a junction with the outer leg and extending laterally and upwardly away from the outer leg, the lower sealing lobe disposed below the upper sealing lobe. 
     In another form thereof, the present disclosure provides a sealing system for sealing a perimeter of a roll-up door and door frame, the sealing system comprising: a bottom seal comprising: a coupling portion having a coupling surface; a primary sealing lobe extending outwardly from the coupling portion, the primary sealing lobe comprising a primary lobe extension extending upwardly from the primary sealing lobe; a secondary sealing lobe extending inwardly from the coupling portion, the secondary sealing lobe comprising a secondary lobe extension extending upwardly from the secondary sealing lobe. 
     In yet another form thereof, the present disclosure provides a sealing system for sealing a perimeter of a roll-up door and door frame, the sealing system comprising: a top seal having a resiliently deformable seal lobe; a cable sealing assembly comprising a bracket having a mounting surface and an opposing, arcuate outer surface, the arcuate outer surface adapted to form a continuous sealing arrangement the resiliently deformable seal lobe; and a cable passage area between the mounting surface and the arcuate outer surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and advantages of this disclosure, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a rear perspective view of a cargo truck including a roll-up door fitted with seals made in accordance with the present disclosure; 
         FIG. 2  is a cross-sectional view of an exemplary seal made in accordance with the present disclosure; 
         FIG. 3  is a plan, cross-sectional view of the seal shown in  FIG. 2 , illustrating assembly of the seal to a roll-up door frame; 
         FIG. 4  is a plan, cross-sectional view, taken along line  3 - 3  of  FIG. 1 , illustrating the seal of  FIG. 3  after assembly to the roll-up door frame; 
         FIG. 5  is a plan, cross-sectional view, taken along line  4 - 4  of  FIG. 1 , illustrating the seal of  FIG. 2  when the roll-up door is in the closed position; 
         FIG. 6  is a cross-sectional view of another exemplary seal made in accordance with the present disclosure; and 
         FIG. 7  is a plan, cross-sectional view of the seal shown in  FIG. 6 , taken along line  4 - 4  of  FIG. 1 , illustrating the seal configuration when the roll-up door is in the closed position. 
         FIG. 8  is a cross-sectional view of yet another exemplary seal made in accordance with the present disclosure; 
         FIG. 9  is a plan, cross-sectional view of the seal shown in  FIG. 8 , taken along line  4 - 4  of  FIG. 1 , illustrating the seal configuration when the roll-up door is in the closed position; 
         FIG. 10  is an elevation view of a portion of a roll-up door frame including a seal made in accordance with the present disclosure; 
         FIG. 11  is a cross-sectional view of a top seal made in accordance with the present disclosure; 
         FIG. 12  is a cross-sectional view of another exemplary top seal made in accordance with the present disclosure; 
         FIG. 12A  is a cross-sectional view of another exemplary top seal made in accordance with the present disclosure, shown in an as-extruded configuration; 
         FIG. 12B  is a cross-sectional view of another exemplary top seal made in accordance with the present disclosure, shown in a mounted, at-rest configuration; 
         FIG. 13  is a cross-sectional view of an exemplary bottom seal made in accordance with the present disclosure; 
         FIG. 13A  is a cross-sectional view of an exemplary seal receiving channel for a bottom seal in accordance with the present disclosure; 
         FIG. 13B  is a cross-sectional view of an exemplary bottom seal adapted to be received in the channel of  FIG. 13A ; 
         FIG. 14  is an elevation, cross-sectional view of a portion of a roll-up door in a closed position, illustrating the top seal of  FIG. 11  shown in a mounted, engaged configuration; 
         FIG. 15  is an elevation, cross-sectional view of a portion of a roll-up door in a closed position, illustrating the top seal of  FIG. 12  shown in a mounted, engaged configuration; 
         FIG. 15A  is an elevation, cross-sectional view of the seal shown in  FIG. 15 , illustrating airflow interaction therewith; 
         FIG. 15B  is an elevation, cross-sectional view of a portion of a roll-up door in a closed position, illustrating the top seal of  FIG. 12A  in a mounted, engaged configuration; 
         FIG. 16  is an elevation, cross-sectional view of a portion of a roll-up door in a closed position, illustrating the bottom seal of  FIG. 13  shown in a mounted, engaged configuration; 
         FIG. 16A  is an elevation, cross-sectional view of a portion of a roll-up door in a closed position, illustrating the bottom seal of  FIG. 13A  shown in a mounted, engaged configuration; 
         FIG. 16B  is a perspective view of a junction between a side and bottom seal in accordance with the present disclosure; 
         FIG. 17  is a perspective, exploded view of a door cable seal made in accordance with the present disclosure; 
         FIG. 18A  is a perspective view of the cable seal assembly of  FIG. 17 , shown fully assembled; 
         FIG. 18B  is another perspective view of the cable seal assembly of  FIG. 18A ; and 
         FIG. 19  is a perspective view of a portion of an upper frame of a roll-up door, with the cable sealing assembly of  FIG. 17  assembled thereto and the top seal of  FIGS. 12 and 15  engaged therewith. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates an exemplary embodiment of the invention, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION 
     1. Side Seals 
     Turning now to  FIG. 1 , seals  10  are shown installed at either side of roll-up door frame  12 , which is positioned at the rear of cargo box  22  mounted to truck  14 . Seals  10  may be identical structures, but are arranged as mirror images of one another so as to have main sealing lobes  40  extending inwardly toward cargo space  20 , as described in further detail below. Roll-up door  16 , sometimes also referred to as an overhead door, includes a plurality of door panels  18  hingedly connected to one another such that each door panel  18  is pivotable about a horizontal axis. In the illustrated embodiment of  FIG. 1 , roll-up door  16  is shown in a partially closed configuration, with seals  10  partially deformed into a sealing configuration in the area where roll-up door  16  is closed. 
     When door  16  is open, cargo space  20  is accessible through the aperture defined by door frame  12 , and door panels  18  are disposed within cargo box  22  such that door panels  18  are all substantially parallel to the roof of cargo box  22 . In the closed configuration, door panels  18  of roll-up door  16  are vertically oriented (as shown in  FIG. 1  with respect to some of the panels  18 ), such that roll-up door  16  blocks access to cargo space  20  from outside cargo box  22 . As described in detail below, seals  10  bear against outer surfaces  50  of door panels  18  to provide a fluid tight seal between cargo space  20  of cargo box  22  and the surrounding environment. 
       FIG. 2  illustrates a cross-sectional profile of seal  10  in an uncompressed state, after manufacture and prior to installation within door frame  12  ( FIG. 3 ). Seal  10  includes coupling body  24  defining longitudinal axis A 1 , which may also be an axis of symmetry for coupling body  24 . Axis A l  extends along insertion direction D I , shown in  FIG. 3 , which is the direction of assembly of seal  10  to door frame  12 , as described in further detail below. Coupling body  24  tapers along axis A 1  from exposed surface  26  toward seating surface  28 , such that side surfaces  30 ,  32  define angle θ therebetween. As illustrated, angle θ is measured without taking into account securement ribs  34 , which extending outwardly from each of side surfaces  30 ,  32 . In an exemplary embodiment, angle θ may be as little as zero, 5 or 10 degrees or may be as large as 20, 25 or 30 degrees, or may be any value within any range defined by any of the foregoing values. In one particular exemplary embodiment, angle θ is about 4 degrees. 
     Seating surface  28  has a generally rounded profile, as shown in  FIG. 2 , to further facilitate initial insertion of coupling body  24  into seal receiving space  36 . Exposed surface  26 , disposed opposite seating surface  28 , is substantially flat (i.e., planar) to facilitate flush mounting with the adjacent edge of a flange  58  of roller track  56 , as shown in  FIGS. 4 and 5  and described in further detail below. 
     Securement ribs  34  are elongate structures as viewed in the cross section of  FIG. 2 , and therefore each define a longitudinal axis A 2 . Each axis A 2  forms an acute angle α with respect to axis A 1  of coupling body  24 , with each of securement ribs  34  configured such that angle α opens away from insertion direction D I  and toward exposed surface  26  of coupling body  24 . As described in further detail below, this configuration allows securement ribs  34  to easily deform when coupling body  24  is seated within seal receiving space  36  ( FIGS. 3 and 4 ), while also resisting removal of coupling body from seal receiving space  36 . In the interest of drawing clarity, the longitudinal axis A 2  of securement ribs  34  is shown for only one of securement ribs  34  on each of side surfaces  30 ,  32 , it being understood that the other securement ribs  34  also define respective axes A 2  forming angle α with respect to the longitudinal axis A 1  of coupling body  24 . In an exemplary embodiment, angle α may be as little as 45, 55 or 65 degrees or may be as large as 75, 85 or 90 degrees, or may be any value within any range defined by any of the foregoing values. In one particular exemplary embodiment, angle α is about 67 degrees. 
     In the illustrated embodiment of  FIG. 2 , three securement ribs  34  are provided on each of side surfaces  30 ,  32 . However, it is contemplated that a larger or smaller number of ribs  34  may be provided to decrease or increase the securement of coupling body  24  within seal receiving space  36 , respectively, as required or desired for a particular application. In an exemplary embodiment, securement ribs  34  are sized and spaced from one another such that each of securement ribs can deform or “fold” down, in the direction of exposed surface  26  of coupling body  24 ) to abut the adjacent side surface  30  or  32  upon installation of seal  10 . Aperture  38  may also be formed within coupling body  24  to facilitate deformation thereof during installation of seal  10 , as also described below. 
     Extending away from exposed surface  26  is main sealing lobe  40 , as best seen in  FIG. 2 . As illustrated, main sealing lobe  40  has a generally arcuate profile in cross-section, with an inner surface  42  forming an arcuate continuation of side surface  30 . When seal  10  is assembled to door frame  12 , side surface  30  is the inwardly facing surface of coupling body  24 , i.e., the surface facing toward the enclosed cargo space  20  of cargo box  22 . Thus, the illustrated position and arrangement of main sealing lobe  40  near inward side surface  30  biases sealing lobe  40  toward door panels  18  when roll-up door  16  is positioned closed, as shown in  FIG. 5  and further described below. 
     Opposite inwardly facing surface  42  of main sealing lobe  40  is outwardly facing surface  44 , which has secondary sealing lobe  46  protruding therefrom. In the illustrative embodiment of  FIG. 2 , main sealing lobe  40  has a substantially constant thickness T M  throughout its arcuate extent, while secondary sealing lobe  46  has a generally triangular profile with a steadily decreasing thickness from the wide base of sealing lobe  46  (at its intersection with main sealing lobe  40 ) to the narrower tip  48  of secondary sealing lobe  46  (i.e., the point on sealing lobe  46  furthest from outer surface  44  of main sealing lobe  40 ). 
     Assembly of seal  10  to door frame  12  is illustrated in  FIG. 3 . Seal  10  is received within seal receiving space  36  such that main sealing lobe  40  is positioned to bear against door panel  18  while secondary sealing lobe  46  bears against an inner surface  54  of flange  52  of door frame  12 . Seal receiving space  36  is a generally rectangular void (as viewed in the plan cross-sectional view of  FIG. 3 ), bounded on three sides by structures of door frame  12  and open on the fourth side. Opposite the open end of seal receiving space  36 , sidewall  62  of door frame  12  forms the “bottom” or base of seal receiving space  36 , against which seating surface  28  bears upon assembly of seal  10  to door frame  12  ( FIG. 4 ). Flange  58  of roller track  56  forms an inward wall of seal receiving space  36 , while flange  52  of door frame  12  forming the opposing outward wall. 
     In certain exemplary embodiments, roller track  56  is fixedly attached to door frame  12 , such as by welding, riveting or other fixed attachment, such that a plurality of rollers  64  connected to door panels  18  via axles  70  ride within roller track  56  as door  16  is raised and lowered ( FIG. 1 ). Door frame  12  may be provided in a standard size and arrangement with roller track  56  affixed thereto in a standard configuration to accommodate mass produced roll-up doors  16  and rollers  64 . 
     Seal receiving space  36  defines width W 1  between outwardly facing surface  60  of track flange  58  and the opposing inwardly facing surface  54  of frame flange  52 . In an exemplary embodiment in the context of roll-up cargo truck doors (such as door  16  shown in  FIG. 1 ), width W 1  may be between 0.5 inches and 1 inch. For other applications in other contexts, the overall profile shown and described herein may be scaled up or down to provide seals usable for other door frame sizes. In one exemplary embodiment, door frame  12  defines width W 1  of 0.88 inches, and the corresponding width of body  24  of seal  10  is about 0.74 inches wide at seating surface  28  and 0.82 inches wide at exposed surface  26 . In this exemplary embodiment, securement ribs are each between 0.06 inches and 0.1 inches wide, and are about 0.25 inches long as measured along axis A 2 . In this exemplary embodiment, the overall length of seal  10  (corresponding to the height of the sides of door frame  12  and shown in  FIG. 1 ) may be about 110 inches. 
     As noted below, seal  10  may be provided in one or more standard sizes to accommodate various industry standard geometries for door frame  12 . More particularly, body  24  of seal  10  may be sized and configured to be received within a standard size seal receiving space  36 , while main sealing lobe  40  and secondary sealing lobe  46  are sized and configured to occupy the space between frame flange  52  and door panels  18 . As further described below, lobes  40 ,  46  may be specifically arranged to fill in a gap having width W 2  between outer surface  50  of door panel  18  and inwardly facing surface  54  of frame flange  52 , while providing a secure sealing arrangement therewithin. 
     Assembly of seal  10  to door frame  12  along insertion direction D I  ( FIG. 3 ) can be accomplished quickly and efficiently. In an exemplary assembly method, body  24  of seal  10  is advanced along insertion direction D I  such that seating surface  28  of body  24  forms the leading edge of seal  10  advancing into seal receiving space  36 . The rounded outer profile of seating surface  28  facilitates initial insertion between flange  58  of roller track  56  and flange  52  of door frame  12 . As coupling body  24  is further advanced along insertion direction D I , the first pair of securement ribs  34  (i.e., those securement ribs  34  which are closest to seating surface  28 ) deflect toward side surfaces  30 ,  32 , respectively. This initial deflection is facilitated by the tapered profile of side surfaces  30 ,  32 , which cooperate to define angle θ ( FIG. 3 ) therebetween. 
     Further advancement of coupling body  24  along direction D I  into seal receiving space  36  deflects the remaining securement ribs  34  as respective pairs of ribs  34  come into contact with frame flange  52  and track flange  58 . As the width between side surfaces  30 ,  32  increases along the tapered outer profile of body  24 , body  24  is more and more tightly received within seal receiving space  36 . To accommodate the eventual interference fit between such wider body portions and seal receiving space  36 , aperture  38  may compress from a circular to ellipsoid configuration as shown in  FIG. 4 . 
     In one exemplary embodiment, width W 1  is equal to about 0.88 inches. As noted above, the corresponding width of body  24  for this exemplary embodiment is about 0.74 inches at seating surface  28 , excluding the adjacent securement ribs  34 , which facilitates initial insertion of body  24  into seal receiving space  36 . However, the final width of body  24  adjacent exposed surface  26  is about 0.82 inches, which cooperates with the about 0.1 inch thick securement ribs  34  to create an interference fit. Thus, the material of body  24  must be deformed to fully seat body  24  within seal receiving space  36 . When body  24  is fully received within seal receiving space  36 , seating surface  28  contacts sidewall  62  of door frame  12 , all of securement ribs  34  are deflected toward their respective side surfaces  30 ,  32 , coupling body  24  is slightly compressed such that aperture  38  is slightly deformed, and exposed surface  26  is substantially flush with the edge of track flange  58 . This fully assembled configuration is illustrated in  FIG. 4 . 
     Although body  24  may be easily received within seal receiving space  36 , a much greater force is required to remove body  24  therefrom. This insertion/removal force differential results from the orientation of securement ribs  34  with respect to longitudinal axis A 1  of coupling body  24 , and therefore with respect to insertion direction D I  ( FIG. 3 ). 
     More particularly, as noted above, securement ribs  34  each define acute angle α with respect to longitudinal axis A 1 , such that angle α opens away from seating surface  28  and toward exposed surface  26 . Upon insertion of coupling body  24  into seal receiving space  36 , this angular arrangement allows securement ribs  34  to deflect toward exposed surface  26  easily and with minimal frictional resistance. However, if coupling body  24  is pulled along a removal direction opposite insertion direction D I , securement ribs  34  bear against inwardly facing surface  54  of frame flange  52  and outwardly facing surface  60  of track flange  58 , respectively. Along this removal direction, angle α defined by securement ribs  34  serves to urge securement ribs  34  to expand away from side surfaces  30 ,  32 , respectively, rather than urging ribs  34  toward contact therewith. This expansion effectively increases the overall width of coupling body  24 , thereby increasing the level of friction between coupling body  24  and surfaces  54 ,  60  of flanges  52 ,  58 , respectively. 
     Thus, the force required to remove coupling body  24  from seal receiving space  36  is substantially higher than the force required to insert coupling body  24  into seal receiving space  36  along insertion direction D I . This force differential allows seal  10  to be effectively used in conjunction with door frame  12  with little or no use of adhesives, fasteners, or other secondary fixation. Using only the material of coupling body  24 , firm securement of seal  10  to door frame  12  can be effected by pushing the coupling body  24  into the seal receiving space  36 . In the exemplary embodiment shown in  FIG. 10 , for example, only the top portion of seal  10  (i.e., the portion near the curved portion of roller track  56 ) is secured within door frame  12  by secondary fixation, such as adhesive. The remainder of seal  10  extending downwardly below such curved portion may be secured only by interaction between coupling body  24  and seal receiving space  36 . 
     In one exemplary embodiment, seal  10  is monolithically formed from EPDM (ethylene propylene diene monomer) rubber having durometer  55 . In other exemplary embodiments, the durometer of the seal material may be as little as 40, 50 or 60 or may be as large as 65, 75 or 85, or may be any value within any range defined by any of the foregoing values. EPDM rubber is highly resistant to degradation from weather and sun, while also being sufficiently soft and pliable to create an effective seal between cargo space  20  of cargo box  22  and the surrounding ambient environment. Accordingly, this material has proven ideal for use with roll-up doors used in cargo trucks and other demanding outdoor environments. 
     In the installed configuration of  FIG. 4 , main sealing lobe  40  and secondary sealing lobe  46  remain in their undeformed state due to the absence of roll-up door  16  at the location of the  FIG. 4  cross-section (as shown in  FIG. 1 ). As roll-up door  16  is advanced from the open to closed position, sealing lobes  40 ,  46  are progressively deformed into a sealing configuration along the extent of seal  10 . In an exemplary embodiment shown in  FIG. 10 , roll-up door frame  12  includes extension  72 , which abuts and aligns with outwardly facing surface  50  of roller track  56  to extend seal receiving space  36  upwardly past the point where track flange  58  of roller track  56  begins its inward bend into cargo space  20 . This effective lengthening of seal receiving space  36  allows seal  10  to be made longer and to extend substantially above the initial inward bend of roller track  56 , such that the first point of contact between the leading edge of door panel  18  and main sealing lobe  40  is substantially spaced away from the end of seal  10 . This in turn prevents sealing lobe  40  from “folding over” upon first contact by panel  18  of door  16 , and promotes proper deformation of lobe  40  into its sealing configuration as described in further detail below. 
     After initial deformation of sealing lobe  40 , outer surfaces  50  of door panels  18  successively come into contact with tip  66  of main sealing lobe  40  further and further down the length of seal  10 . This “zipper” effect progressively forces lobe  40  outwardly (i.e., in a direction away from cargo space  20  of cargo box  22 ), which in turn advances tip  48  of secondary sealing lobe  46  into contact with inwardly facing surface  54  of frame flange  52  as illustrated in  FIG. 5 . Lobes  40 ,  46  are sized and configured to occupy a space between door panel  18  and frame flange  52  that is slightly larger than width W 2 , such that slight compression and deformation of lobes  40  and  46  occurs. This compression forms a pair of firm, fluid-tight seals between cargo space  20  and the ambient environment around cargo box  22 . 
     Because lobes  40 ,  46  are forcibly deformed into their sealing configurations shown in  FIG. 5 , the resiliency of the material of seal  10  serves to bias tips  66 ,  48  of lobes  40 ,  46  toward contact with their respective sealing surfaces  50 ,  54 . This spring-like bias force maintains the redundant pair of fluid-tight seals formed by seal  10 , even if movement or vibration of door panels  18  and/or door frame  12  occurs (such as while truck  14  is moving). Moreover, the deformation of main sealing lobe  40  serves to “push” secondary sealing lobe  46  into its sealing arrangement, which in turn “pushes back” against main sealing lobe  40 . In this way, sealing lobes  40 ,  46  act as mutually opposed biasing elements urging one another into sealing contact with their mutually opposed sealing surfaces  50 ,  54  respectively. Such biased contact between lobes  40 ,  46  and the adjacent sealing surfaces  50 ,  54  ensures that a lasting, durable fluid-tight seal will form even as the material of seal  10  becomes weathered over time. 
     The amount of bias force provided by main sealing lobe  40  toward outer surface  50  of door panel  18  can be raised or lowered by changing the size and geometry of lobe  40 . For example, thickness T M  ( FIG. 2 ) may be increased to elevate the biasing force, or decreased to reduce the biasing force. In an exemplary embodiment designed for a seal receiving space  36  having width W 1  of 0.88 inches and a door frame arrangement defining width W 2  of 0.688 inches (with a tolerance of +/−0.063 inches), thickness T M  is 0.19 inches. 
     Another variable affecting the biasing force is the undeformed radius of curvature R defined by lobe  40  (shown in  FIG. 2  as radius R at inwardly facing surface  42 ). If radius R is increased, the biasing force will decrease because the amount of material deformation will be reduced. Conversely, a decrease in radius R will cause an increase in material deformation and a concomitant increase in biasing force. As biasing force increases, sealing deformation and the ability of lobe  40  to span width W 2  increases. In the exemplary embodiment discussed above, radius R is about 0.5 inches. In the exemplary embodiments shown in  FIGS. 6-9  and described in detail below, radii R 100 , R 200  are 2.3 about inches. For larger or smaller seal arrangements, such as those having larger or smaller width W 2 , the overall size of lobe  40  will increase accordingly. However, the overall thickness of lobe  40  may remain substantially constant. 
     Similarly, secondary sealing lobe  46  may be changed in size and thickness to provide greater or lesser biasing force against inwardly facing surface  54  of frame flange  52 . In the exemplary embodiment referenced above for a width W 1  of 0.88 inches for seal receiving space  36  and width W 2  of 0.688 to 0.748 inches, lobe  46  may extend an appropriate distance away from outwardly facing surface  44  of lobe  40 , measured as the shortest distance from the extrapolated outer surface  44  to the end of tip  48  of lobe  46 . In the case of seal  10 , this distance may be about 0.5 inches. Lobe 46 may also define an overall width at the base thereof equal to about 0.38 inches. The overall length and/or width dimensions can be increased to increase the biasing force provided by lobe  46 , or may be decreased to decrease such biasing force. Although lobe  46  is shown as being made of solid material in  FIGS. 2-5 , an aperture may be provided therein to reduce the biasing force provided by lobe  46 . 
     In an exemplary embodiment, lobes  40  and  46  of seal  10  are designed to provide a high enough level of biasing force against their respective sealing surfaces  50 ,  54  to create a reliably fluid-tight seal, while being low enough to prevent undue friction against door panels  18 . In this embodiment, the appropriate level of biasing force can be calculated within a range of forces that both a) reliably creates a fluid-tight seal and b) results in a friction force sufficiently low to allow the user of roll-up door  16  to manually open and close roll-up door  16 . 
     As illustrated in  FIG. 5 , when door  16  is in the closed position tip  66  extends laterally toward the middle of door panel  18  by a substantial distance, i.e., the distance between exposed surface  26  and tip  66  of lobe  40 . In the exemplary embodiment described above adapted for use with a seal receiving space  36  having width W 1  of 0.88 inches, this lateral distance may be about 1.5 inches or more. This allows seal  10  to reliably bias against outer surface  50  of door panel  18 , even if lateral edge  68  ( FIG. 5 ) of door panels  18  of door  16  are variably spaced from sidewall  62  of door frame  12 . For example, in some standard roll-up door designs, axle  70  of rollers  64  may be longer or shorter than in other standard designs, thereby changing the lateral position of edge  68  of door panels  18 . In other cases, rollers  64  (and therefore door panels  18 ) are allowed to shift laterally within roller track  56  as the roll-up door  16  opens or closes. Such lateral shifting may be significant, such as up to 0.5 inches in either lateral direction. Seal  10 , with its long sealing lobe  40 , is usable on all such standard door frame designs despite variations in the exact size and configuration, and potential lateral shift of the corresponding roll-up door. 
     As described above, seal  10  may be installed quickly and efficiently without tools, and with little or no use of adhesives or other secondary fixation structures. Coupling body  24  is simply advanced laterally, i.e., along direction D I  ( FIG. 3 ) such that the installer standing near cargo box  22  passes seal  10  toward sidewall  62  of frame  12 . This lateral advancement is complete when coupling body  24  is fully received within seal receiving space  36 . When so installed, coupling body  24  is captured within seal receiving space  36 , as discussed in detail above, and sealing lobes  40 ,  46  protruded outwardly from seal receiving space  36 . In one exemplary embodiment, such installation may be effected without fasteners or adhesives. In another exemplary embodiment, a minimal amount of such auxiliary coupling aids is used, such as at the top of seal  10  as described above. Seal  10  is installed along its length such that the sides of door frame  12  are completely sealed. 
     To uninstall seal  10 , seal  10  can be simply grasped (e.g., by sealing lobe  40 ) and pulled free from seal receiving space  36  and door frame  12 . Although seal  10  requires an elevated amount of force to remove from seal receiving space  36 , such force can be marshaled by a maintenance person when needed to uninstall and replace seal  10 . Such uninstallation is simplified by the minimal use (or lack of) fasteners and adhesives used in the initial installation. Thus, seal  10  may be readily replaced whenever such replacement becomes necessary. Moreover, because seal  10  can be made from a single, monolithic extruded material as detailed above, replacement seals  10  can be produced in large quantities for a minimal cost. 
     Turning now to  FIG. 6 , a cross-sectional profile of alternative seal  110  is shown. Seal  110  is similar to seal  10  described above, with reference numerals of seal  110  analogous to corresponding reference numerals used in seal  10 , except with  100  added thereto. Structures of seal  110  correspond to similar structures denoted by corresponding reference numerals of seal  10  except as otherwise noted, and seal  110  is installed to door frame  12  in a similar fashion as described above (and as shown in  FIG. 7 ). 
     However, coupling body  124 , main sealing lobe  140  and secondary sealing lobe  146  of seal  110  have unique geometries which provide seal  110  with unique sealing characteristics. Coupling body  124  has a narrower overall narrower profile but with longer securement ribs  134  extending therefrom. This arrangement allows for more pronounced deformation of securement ribs  134  upon assembly into seal receiving space  36  (as shown in  FIG. 7 ), and obviates the need for aperture  38  used in seal  10  ( FIG. 2 ). Also, as most clearly illustrated by a comparison of  FIGS. 5 and 7 , the overall length of seal  110  is also substantially longer than that of seal  10 . In an exemplary embodiment, the largest cross-sectional dimension of seal  110  in the undeformed state of  FIG. 6  is about 2.73 inches. The overall undeformed width W S  of coupling body  124  is about 0.71 inches, such that seal  110  is suitable for use in door frame  12  having a width W 1  of seal receiving space  36  ( FIG. 3 ) equal to 0.5 inches. 
     Main sealing lobe  140  has a substantially reduced curvature in its at-rest, undeformed state as shown in  FIG. 6 . Accordingly, radius R 100  defined by the concave cross-sectional profile of inner surface  142  of lobe  140  is substantially larger than radius R of lobe  40  of seal  10 . As noted above, such a reduction in the curvature of lobe  140  as compared to lobe  40  produces less biasing force against outer surface  50  of door panels  18  when seal  110  is in its sealing, deformed state ( FIG. 2 ). Concomitantly, less friction is produced at the area of contact between tip  166  and outer surfaces  50  of respective door panels  18  of roll-up door  16 . For certain exemplary embodiments, such as roll-up doors commonly found on the rear enclosures of cargo trucks, the large-radius arrangement shown in  FIG. 6  has been found to provide a firm, liquid-tight seal while preventing undue friction. 
     Main sealing lobe  140  also lacks the constant thickness T M  found in lobe  40  of seal  10  ( FIG. 2 ). Instead, lobe  140  defines a relatively constant thickness T M100  ( FIG. 6 ) between exposed surface  126  and secondary sealing lobe  146 , then a tapering thickness between secondary sealing lobe  146  and tip  166  (where tip  166  is at the end of the longitudinal extent of lobe  140 , opposite exposed surface  126  as shown in  FIG. 6 ). Stated another way, the shortest distance between concave inner surface  142  and the opposing, convex outer surface  144  of sealing lobe  140  steadily decreases as one traverses the longitudinal extent of main sealing lobe  140  from secondary sealing lobe  146  to tip  166 . 
     Secondary sealing lobe  146  retains the generally triangular profile found in secondary sealing lobe  46  of seal  10 , but is more nearly equilateral in overall shape and has aperture  147  formed therein. As shown in  FIG. 7 , when seal  10  enters its sealing configuration with respect to door panel  18 , secondary sealing lobe  146  substantially deforms to create a liquid-tight seal with inwardly facing surface  54  of flange  52  of door frame  12 . More particularly, a first lobe wall  146 A, extending from toward tip  166  of main sealing lobe  140 , resiliently deforms into a “buckled” configuration, as shown in  FIG. 7 , when tip  148  of lobe  146  (i.e., the point on sealing lobe  146  furthest from outer surface  144  of main sealing lobe  140 ) is urged into contact with inwardly facing surface  54 . This buckling causes first lobe wall  146 A to protrude into aperture  147  as illustrated, so that tip  148  of secondary sealing lobe  146  deflects in an opposite direction to that of tip  166  of main sealing lobe  140 . 
     The resiliency of the material of first lobe wall  146 A, i.e., the tendency of first lobe wall  146 A to return to its undeformed configuration, provides a constant biasing force urging main sealing lobe  140  toward outer surface of door panel  18 . This force biases lobe tip  166  into sealing engagement with surface  50 , in similar fashion as described above with respect to seal  10 . Meanwhile second lobe wall  146 B, which is located opposite first lobe wall  146 A and extends toward coupling body  124  as shown, is urged into sealing contact with inner surface  54  of flange  52  by the resilient deformation of main sealing lobe  140 , such that lobes  140 ,  146  bias each other into sealing engagement. In addition, the extended sealing contact of second lobe wall  146 B across a substantial portion of second lobe wall  146 B, such as about half of its cross sectional extent as illustrated, providing a reliably liquid-tight seal at surface  54 . In an exemplary embodiment, the above-described sealing action can be achieved with a lobe wall thickness TL ( FIG. 6 ) of about 0.07 inches. 
     Turning to  FIGS. 8 and 9 , a cross-sectional profile of another alternative seal  210  is shown. Seal  210  is similar to seals  10 ,  110  described above, with reference numerals of seal  210  analogous to corresponding reference numerals used in seal  10 ,  110 , except with  100  or  200  added thereto respectively. Structures of seal  210  correspond to similar structures denoted by corresponding reference numerals of seals  10 ,  110  except as otherwise noted, and seal  210  is installed to door frame  12  in a similar fashion as described above (and as shown in  FIG. 9 ). 
     In an exemplary embodiment, seal  220  is identical to seal  120  except at the junction between main sealing lobe  240  and coupling body  224 . More particularly, seal  220  lacks the constant-thickness section found main sealing lobe  140  (i.e., that portion of sealing lobe  140  having thickness T M100 ) and instead has a steadily increasing thickness toward coupling body  224 . As above, this thickness is measured as the shortest distance from concave inner surface  242  to convex outer surface  244 , taken along any point along the longitudinal extent of the illustrated cross-section of sealing lobe  240 . As illustrated, this arrangement eliminates any analog to exposed surfaces  26 ,  126  in seal  210 , with convex outer surface  244  of main sealing lobe  240  instead blending smoothly with side surfaces  232  of coupling body  224 . This profile enhances the strength of the connection between lobe  240  and coupling body  224 , and provides some additional biasing force to tip  266  of lobe  240 . 
     Referring back to  FIG. 1 , bottom seal  74  and/or top seal  76  may also be provided as needed to complete liquid-tight seal around roll-up door  16 . Bottom and/or top seals  74 ,  76  may be used in a known configuration, except that the ends of bottom seal  74  may be trimmed as necessary to accommodate seals  10 ,  110  or  210  on either side of door  16 . 
     2. Top Seal 
     Turning now to  FIG. 11 , an exemplary top seal  76 A is illustrated in cross-section. Seal  76 A may be a monolithic, uniform extruded or cast part, similar to side seals  10 ,  110 ,  210 , and may be cut to an appropriate length to span the upper portion of roll-up door  16  ( FIG. 1 ). 
     Except as otherwise described below, top seal  76 A has a number of features similar to seals  10 ,  110 ,  210  described above, and reference numerals of seal  76 A are analogous to corresponding reference numerals used in seals  10 ,  110 ,  210  except with  300 ,  200  or  100  added thereto respectively. Structures of seal  76 A correspond to similar structures denoted by corresponding reference numerals of seals  10 ,  110 ,  210  except as otherwise noted. 
     However, unlike side seals  10 ,  110  and  210 , top seal  76 A utilizes different coupling structures for mounting seal  76 A to roll-up door  16  (rather than to door frame  12 ), and utilizes differently shaped and arranged sealing lobes to effect redundant sealing surfaces between door frame  12  and the upper-most panel  18  of door  16  when door  16  is in the closed position. 
     Referring still to  FIG. 11 , top seal  76 A includes inner leg  330  and outer leg  332 , both of which extend downwardly in substantially parallel fashion when seal  76 A is mounted to door panel  18  (as shown in  FIG. 14  and described in detail below). Door seating surface  328  spans the distance D between legs  330 ,  332  such that legs  330 ,  332  and seating surface  328  all cooperate to define coupling recess  324  which is sized and configured to receive an upper edge of door panel  18 . In an exemplary embodiment, legs  330 ,  332  may define an at-rest, undeformed state in which legs  330 ,  332  converge toward one another as legs  330 ,  332  extend downwardly away from seating surface  328 , such that one or both of legs  330 ,  332  may elastically deform to conform to the upper edge of door panel  18  and thereby resiliently grip the door edge. In this way, seal  76 A may be firmly affixed to door panel  18 , rendering the use of additional adhesives or other fixation devices optional. As shown in  FIG. 14 , when seal  76 A is fully installed upon door panel  18 , the upper edge of the upper-most door panel  18  of door  16  abuts seating surface  328 , while outer leg  332  abuts outer surface  50  and inner leg  330  abuts the opposing inner surface  51  of door panel  18 . 
     Seal  76 A includes a primary sealing lobe  340  and a secondary sealing lobe  346 . Similar to the corresponding lobe structures of side seals  10 ,  110 ,  210  described above, primary sealing lobe  340  provides an outer barrier to fluid ingress into cargo space  20 . This barrier is formed by sealing engagement of upper portion  80 A of door frame  12  with lobe  340  when door  16  is in the closed position, as described further below. Seal  76 A also includes secondary sealing lobe  346  which provides a second, redundant fluid-tight seal disposed between cargo space  20  and primary sealing lobe  340 , such that a further barrier against ingress of fluid or other contaminants into cargo space  20  is provided in addition to primary lobe  340 . 
     Primary sealing lobe  340  includes outer and inner lobe walls  340 A,  340 B which, in cooperation with outer leg  332 , define aperture  341  extending through lobe  340 . As shown in  FIG. 14 , when door  16  is in the fully closed position (i.e., when the upper-most door panel  18  is a generally vertical orientation along with the remaining panels  18  of door  16 ), primary lobe  340  resiliently deforms to seal against horizontal flange  358  of upper portion  80 A of door frame  12 . More particularly, an inner surface of inner lobe wall  340 B abuttingly engages downwardly facing surface  360  of horizontal flange  358 , while also partially compressing aperture  341  as lobe  340 B moves toward  340 A. Lobe  340 A may also partially deform, as illustrated. 
     In use, as upper panel  18  of door  16  moves toward a closed position while rollers  64  ride through roller track  56  (see e.g.,  FIG. 7 ), outer lobe wall  340 A makes initial contact with upper frame portion  80 A. As upper door panel  18  continues to move downwardly and pivot toward a vertical orientation from a horizontal orientation, lobe  340  “pops” or “rolls” from a first deformed state in which outer lobe wall  340 A abuts vertical flange  352  of upper frame portion  80 A into the sealing configuration shown in  FIG. 14  in which inner lobe wall  340 B abuttingly engages horizontal flange  358 . 
     Secondary sealing lobe  346  comes to rest against vertical flange  352  when door  16  is in the fully closed position, as shown in  FIG. 14 . Specifically, outer sealing lobe  346 B comes into abutting contact with inwardly facing surface  354  of vertical flange  352 , which in turn resiliently deforms outer and inner sealing lobes  346 B,  346 A and compresses aperture  347  in similar fashion to the sealing deformation of aperture  341 . 
     In this way, top seal  76 A provides a dual-contact, redundant sealing engagement with upper frame portion  80 A along two different flanges thereof, in which the two different flanges are angled (e.g., at right angles), as illustrated in  FIG. 14 . 
     Turning now to  FIG. 12 , an alternative top seal  76 B is illustrated in cross-section. Top seal  76 B is structurally and functionally similar to top seal  76 A described in detail above, with reference numerals of seal  76 B analogous to corresponding reference numerals used in seal  76 A, except with  100  added thereto. Structures of seal  76 B correspond to similar structures denoted by corresponding reference numerals of seal  76 A except as otherwise noted, and seal  76 B is amenable to similar methods for installation and use in conjunction with door  16  and door frame  12 . In the interest of clarity and conciseness, only those features of seal  76 B which differ from the corresponding features of seal  76 A are described below, it being understood that all other features of seal  76 A may also be present in seal  76 B. 
     Primary sealing lobe  440  has a similar structure and arrangement as compared to primary sealing lobe  340 , except with a modified shape for the features and geometry of upper frame portion  80 B ( FIG. 15 ). Moreover,  FIGS. 11 ,  12 ,  12 A,  12 B,  13 ,  13 A and  13 B are all drawn to scale, and so variations in lobe geometry for primary lobes  340  and  440  are as shown. In the illustrated embodiments of  FIGS. 11 ,  12  and  13  (discussed below), distance D between legs  330 ,  332 , legs  430 ,  432 , legs  530 ,  532 , legs  730 ,  732 , or legs  830 ,  832  when seals  74 A,  74 B,  76 A,  76 B,  76 C are mounted upon door  16  is 0.510 inches. Other dimensions of seals  74 A,  74 B,  76 A,  76 B,  76 C may be measured from the respective figures in view of this relative scale provided by dimension D. 
     In the case of seal  76 B, outer lobe wall  440 A includes a slightly convex curvature rounding to a broader point with inner lobe wall  440 B, and inner lobe wall  440 B defines a slightly concave outer surface. 
     Top seal  76 B includes an elongate, fin-like secondary sealing lobe  446  rather than the dual-wall arrangement of sealing lobe  346  shown in  FIG. 11  and described in detail above. As described in further detail below, this fin-like sealing lobe  446  is adapted to interact with cable sealing assembly  600  ( FIGS. 17-22 ) to eliminate a potential leak path between cargo space  20  and the ambient environment in the vicinity of upper frame portion  80 B. 
     As shown in  FIG. 15 , when door  16  is in the closed position such that upper panel  18  is substantially vertical, primary sealing lobe  440  sealing abuts an end surface  460  of horizontal flange  458  of upper frame portion  80 B. In addition, L-shaped bracket  452  may be affixed to upper frame portion  80 B to provide a horizontal sealing surface  455  against which lobe  440  may also seal. In the illustrated embodiment, a tip of lobe  440  provides a primary seal surface at the junction between outer and inner lobe walls  440 A,  440 B. It is also contemplated that inner lobe wall  440 B may seal on horizontal sealing surface  455  alone, similar to the sealing arrangement of primary sealing lobe  340  described above. 
     Secondary sealing lobe  446  biases against inwardly facing surface  454  of L-shaped bracket  452  to provide a secondary, redundant seal against ingress of fluids or other contaminants into cargo space  20 . More particularly, as shown in the dashed-line configuration of secondary sealing lobe  446  in  FIG. 15 , outwardly-facing lobe surface  446 B sealingly abuts inwardly facing surface  454  to provide such second seal. Lobe  446  also includes inwardly-facing surface  446 A ( FIG. 12 ) opposite sealing surface  446 B. 
     Top seal  76 B further includes airfoil  482  formed on outer leg  432 , as illustrated in  FIGS. 12 and 15 . Airfoil  482  is formed as an outwardly shaped point with a downwardly facing, slightly concave lower surface  484 . As turbulent air passes over the top of cargo box  22  when truck  14  is in transit (i.e., moving forward), turbulent airflows in the vicinity of top seal  76 B tend to swirl and drive air and/or precipitation upwardly against upper door panel  18  and upper frame portion  80 B. It has been empirically determined that provision of airfoil  482  with concave lower surface  484  produces a “spoiler effect” which diverts this turbulent flow of air and/or precipitation away from primary sealing lobe  440 , as illustrated schematically in  FIG. 15A . This spoiler effect eliminates a source of potential weathering and high pressure leak potential acting against primary sealing lobe  440 . 
     Although airfoil  482  is shown in the figures as being integrally formed with outer leg  432  of top seal  76 B, it is contemplated that a similar structure may be formed as part of outer leg  332  of top seal  76 A discussed above. Airfoil  382  having concave lower surface  384  is schematically illustrated in  FIG. 11 . 
     Turning now to  FIGS. 12A ,  12 B and  15 B, another exemplary top seal  76 C is illustrated in as-extruded, mounted at-rest, and engaged configurations, respectively. 
     Except as otherwise described below, top seal  76 C has a number of features similar to top seals  76 A and  76 B described above, and reference numerals of seal  76 C are analogous to corresponding reference numerals used in top seals  76 A and  76 B except that reference numbers for seal  76 C take the form  7 XX (e.g., sealing lobe  740 ) compared to the form  3 XX and  4 XX used in seals  76 A and  76 B respectively (e.g., sealing lobes  340 ,  440  respectively). Structures of seal  76 C correspond to similar structures denoted by corresponding reference numerals of seals  76 A and  76 B except as otherwise noted, and seal  76 C is amenable to similar methods for installation and use in conjunction with door  16  and door frame  12 . In the interest of clarity and conciseness, only those features of seal  76 C which differ from the corresponding features of seals  76 A and  76 B are described below, it being understood that all other features of seal  76 A,  76 B may also be present in seal  76 C. 
     However, unlike top seals  76 A and  76 B, top seal  76 C includes two elongate, fin-like sealing lobes  746  and  743  which both engage inner surface  454 , together with airfoil lobe  782  which uses expected patterns of airflow A ( FIG. 15B ) at the rear of cargo box  15  ( FIG. 1 ) to divert a primary portion of the flow of fluid F away from the sealing engagement between lobes  746  and  743  and inner surface  454 . 
     Similar to the other seals described herein, top seal  76 C is formed as a unitary, monolithic structure such that its entire cross-sectional shape has a constant durometer throughout. In order to achieve this monolithic form, seal  76 C may be extruded from bulk material, such as EPDM, and cut to length for installation on the sides of door  16  as described above.  FIG. 12A  illustrates seal  76 C in its as-extruded form, prior to installation on door  16 , while  FIG. 12B  illustrates seal  76 C installed on door  16  but otherwise undeflected. By comparison of  FIGS. 12A and 12B , the resilient deflection of seal  76 C upon mounting can be appreciated. 
     As extruded, coupling recess  724  is partially collapsed such that inner leg  730  is angled toward outer leg  732 , and outer leg  732  defines a bent “reverse-J-shaped” profile as shown in  FIG. 12A . To mount the as-extruded seal  76 C to door  16 , the lower end of outer leg  732  is first adhesively attached to an appropriate location on outer surface  50  of door  16 . Seal  76 C is then mounted to the edge of door  16  ( FIG. 12B ) via legs  730 ,  732 , such that inner leg  730  resiliently deforms to provide a securement force, while coupling portion  731  bridging legs  730 ,  732  abuts the upper edge of door  16 . This attachment resiliently deflects outer leg  732  and the structures attached thereto, such that upper and lower sealing lobes  746 ,  740  and airfoil lobe  782  are reconfigured from the as-extruded “reverse-J-shape” into a service configuration ( FIG. 12B ) in which the entirety of outer leg  732  is made substantially straight and drawn against outer surface  50 . Adhesive may also be applied between inner leg  730  and the adjacent interior surface of door panel  18  for further securement. 
     In the service configuration of  FIG. 12B , the inverted U-shape of coupling recess  724  is formed by inner leg  730  which forms a junction with the upper bridge  731 , and outer leg  732  which forms a junction with at an opposing end of upper bridge  731  opposite inner leg  730 . In this way, inner leg  730 , outer leg  732  and bridge  731  define the U-shaped door receiving space  724  with an open lower end. 
     Upper sealing lobe  746  extends laterally and upwardly away with respect to outer leg  732  and, more particularly, sealing lobe  746  extends upwardly and outwardly from its junction with bridge portion  731  as best seen in  FIG. 18B . Lower sealing lobe  740  is formed of multiple individual portions, including first lobe wall  740 A forming a junction with a lower end of outer leg  732  and extending laterally and upwardly away from outer leg  732 , second lobe wall  740 B forming a junction with an upper end of outer leg  732  and with the end of first lobe wall  740 A, and lobe extension  743  extending laterally and upwardly away from the junction between the first and second lobe walls  740 A,  740 B. First lobe wall  740 A, second lobe wall  740 B and outer leg  732  form a triangular lobe structure which provides a base of structural support for lobe extension  743 , such that lobe extension  743  can resiliently bias against sealing surface  454  as shown in  FIG. 15B  and described further below. 
     In an exemplary embodiment, living hinge  745  is formed in first lobe wall  740 A adjacent to and just below the junction between first and second lobe walls  740 A and  740 B. Living hinge  745  facilitates resilient deflection of the triangular lobe structure in a predictable manner to provide the desired kind and character of resilient support to lobe extension  743  for a firm seal with sealing surface  454  ( FIG. 15B ). 
     As noted above, top seal  76 C also includes airfoil lobe  782 , which operates to direct a flow of water F and air A upwardly and away from the upper and lower sealing lobes. Airfoil lobe  782  forms a junction with a lower end of outer leg  732 , as well as with first lobe wall  740 A, and is positioned below lower sealing lobe  740  while extending generally laterally and upwardly away from outer leg  732  in a similar fashion to sealing lobes  746 ,  743 . However, airfoil lobe stops short of contact with any portion of upper frame portion  80 B, and therefore does not participate in the structural deflection characteristics of lobes  740 ,  746 . In an exemplary embodiment, airfoil lobe  782  defines a concave surface  784  facing outwardly and downwardly which directs water F along the illustrated trajectory toward contact with horizontal flange  458  of upper frame portion  80 B, where airflow A carries water F rearwardly and away from cargo box  15 . In this way, airfoil lobe  782  substantially prevents the ingress of rainwater at the sealing engagement between lower and upper sealing lobes  743 ,  746  and sealing surface  454 . 
     Meanwhile, lobes  740 ,  746  cooperate to present a large-area sealing engagement with sealing surface  454  of bracket  452 , thereby providing a fluid-tight seal to prevent any fluid (e.g., air, water, or airborne particulate matter) from passing between the interior and exterior of cargo box  15  along the upper edge of door  16 . In addition, the illustrated arrangement of lower and upper sealing lobes  740 ,  746  cooperates with bracket  452  (or any other adjacent substantially vertical sealing surface) to create air pocket  733 , which is a “dead air” space that insulates the sealing engagement between lobe  746  and sealing surface  454  from wind and turbulence outside cargo box  15 . 
     3. Bottom Seal 
     Turning now to  FIG. 13 , bottom seal  74 A is illustrated. Similar to top seals  76 A,  76 B, bottom seal includes inner and outer legs  530 ,  532  which span seating surface  528 , all of which cooperate to form coupling recess  524  sized and adapted to attach bottom seal  74 A to a bottom edge of a lower surface panel  18  of door  16 , in similar fashion to the manner of connection for top seals  76 A,  76 B to the upper edge of the upper most panel  18  of door  16 . 
     Bottom seal includes outer sealing lobe  540  and inner sealing lobe  546 , which may be substantial mirror images of one another as illustrated in  FIG. 13 . Lobes  540 ,  546  include sealing lobe walls  540 B,  546 A respectively which, when door  16  is in the closed position, engage upper surface  560  of lower frame portion  558  of door frame  12 , as shown in  FIG. 16 . Similar to top seals  76 A,  76 B above, this deformation alters the shape and configuration of apertures  541 ,  547  and non-contacting lobe walls  540 A,  546 B, respectively. In addition, bottom seal  74 A may include a plurality (such as three shown in  FIGS. 13 and 16 ) of auxiliary sealing lobes  586  which also resiliently deform in sealing engagement with lower frame portion  558  when in contact with upper surface  560  thereof 
     Turning to  FIGS. 13B and 16A , an alternative bottom seal  74 B is shown. Except as otherwise described below, bottom seal  74 B has a number of features similar to bottom seal  74 A and the other seals described above, and reference numerals of seal  74 B are analogous to corresponding reference numerals used in seals  74 A and the other seals described herein, except that reference numbers for seal  74 B take the form  8 XX (e.g., sealing lobe  840 ) compared to the form  5 XX used in seal  74 A (e.g., sealing lobe  540 ). Structures of seal  74 B correspond to similar structures denoted by corresponding reference numerals of seals  74 A and the other seals described herein except as otherwise noted. 
     Unlike other seals described herein, bottom seal  74 B mounts to the bottom edge of door  16  via a coupler  888 , which in the illustrated embodiment takes the form of an aluminum extrusion having the cross-sectional profile shown in  FIG. 13A . Coupler  888  includes inner and outer legs  830 ,  832  which are spaced apart by distance D (described above) in order to mount to door  16  as shown in  FIG. 16A . Seating surface  828  forms a shelf adjacent to outer leg  832 , which provides for inwardly angled surface  892  at the bottom of outer leg  832  as further described below. A seal receiving space  890  is shaped and sized to receive a correspondingly sized coupling portion  898  of seal  74 B. Seal  74 B can be fixed to coupler  888  by adhesive between upper surface  828 A and the abutting surface of seal receiving space  890 , and/or by periodic fasteners, such as nail  896 , driven through seal  74 B and the lower wall of coupler  888  ( FIG. 16A ). 
     Bottom seal  74 B includes a primary outer sealing lobe  840 , having inner lobe wall  840 B and outer lobe wall  840 A, and a secondary inner sealing lobe  846  having outer lobe wall  846 A and inner lobe wall  846 B. Lobes  840 ,  846  define apertures  841 ,  847  respectively in cross-section, each aperture sized and positioned to compress when the auxiliary sealing lobe is deformed by contact with an adjacent sealing surface ( FIG. 16A ). 
     Primary lobe extension  840 C extends upwardly from primary sealing lobe  840 , and is joined to an upper end of outer lobe wall  840 A as shown in  FIG. 13B . Similarly, secondary lobe extension  846 C extends upwardly from secondary sealing lobe  846 , and is joined to an upper end of inner lobe wall  846 B. As described further below, primary and secondary lobe extensions  840 C,  846 C are sized and arranged to contact an outer surface of the coupler when the primary sealing lobe is deformed by contact with an adjacent sealing surface ( FIG. 16A ). In an exemplary embodiment, bottom seal is substantially symmetrical about a bisecting vertical plane such that outer and inner sealing lobes  840 ,  846  are mirror images of one another. 
     Auxiliary sealing lobe  886  is disposed between outer and inner lobes  840  and  846  and extends downwardly from coupling portion  898 . Aperture  899  may be formed in coupling portion  898 , as view in cross section ( FIG. 13B ) which is sized and positioned to compress when auxiliary sealing lobe  886  is deformed by contact with an adjacent sealing surface ( FIG. 16A ). 
     In use, door  16  advances downwardly until lobes  840 ,  846  contact upper surface  560  of lower frame portion  558  of door frame  12 , as shown in  FIG. 16A . As lobe  840  deflects upwardly, lobe extension  804 C contacts ramped surface  892  of coupler  888  and is resiliently deflected to established a large-area seal therebetween. At the same time, secondary lobe extension  846  also comes in to contact with coupler  888  at inner surface  894 , but makes a lesser area of contact. The outer seal lobe extension  840 C therefore provides a primary seal between the outside and inside of cargo box  15 , while the inner lobe extension  846 C makes a secondary area of contact for a redundant seal. Yet another redundant sealing contact is made between auxiliary lobe  886  and upper surface  560 . 
     4. Cable Seal 
     Turning now to  FIGS. 17-19 , cable sealing assembly  600  is illustrated. As best seen in  FIG. 17 , cable sealing assembly  600  includes bracket  602  having a smooth, arcuate outer surface  604  and a pair of opposing, substantially planar mounting surfaces  606 . In between respective mounting surfaces  606  is a cable passage area  608  which includes brush seal mounting grooves  610  and bushing roller groove  612 . As illustrated by a comparison of the exploded view of  FIG. 17  with the assembled view of  FIG. 18B , brush seals  614  are interfittingly received within respective brush seal mounting grooves  610 , while cable bushing  616  is received within roller groove  612  and between brush seals  614 . In an exemplary embodiment, cable bushing  616  is a two-piece arrangement split along the longitudinal axis thereof to facilitate attachment to cable  620 . 
     Bracket  602  includes mounting apertures  618  extending from arcuate outer surface  604  through planar mounting surfaces  606 . As shown in  FIG. 19 , as well as in  FIG. 15 , cable sealing assembly  600  mounts to upper frame portion  80 B at vertical surface  454  by passing fasteners through apertures  618  and into the underlying frame material. 
     Cable  620  is received through a central aperture of cable bushing  616  and passes through each of the adjacent brush seals  614 , as best seen in  FIG. 18B . In the context of truck  14  ( FIG. 1 ), cable  620  is wound upon cable spool  622  ( FIG. 19 ), which in turn is fixed to torsion spring  624  mounted adjacent upper frame portion  80 B. Torsion spring  624  may contain stored mechanical energy when door  16  is in the closed position, which energy is released to assist in the upward movement of door  16  to the open position in known fashion. That is, as door  16  is opened, cable  620  (which is attached to one of the lower panels  18  of door  16 ) transmits the torsion force of spring  624  to door  16  as cable  620  spools onto cable spool  622 . 
     Because cable  620  is located between door  16  and the ambient outside environment, but spring  624  is located within cargo space  20  of cargo box  22 , the passage of cable from the outside environment into cargo space  20  creates a potential leak path. In order to seal this leak path, cable sealing assembly  600  provides brush seals  614  to prevent or inhibit the flow of air past cable  620 . At the same time, the smooth, gradually transitioning arcuate profile of outer surface  604  of bracket  602  provides a sealing surface upon which sealing lobe  446  of top seal  76 B can be consistently sealingly engaged. In this way such, the sealing engagement of seal  76 B with inwardly facing surface  454  is not interrupted by cable  620 . That is to say, referring to  FIGS. 15 and 19 , sealing surface  446 B of lobe  446  may sealingly engage with surface  454  of bracket  452  on either side of cable sealing assembly  600 , while also sealingly engaging with the entire longitudinal arcuate extent of arcuate outer surface  604  of bracket  602 , thereby creating an uninterrupted upper sealing engagement between top seal  76 B and upper frame portion  80 B. In the case of top seal  76 C, similar engagement occurs between lobes  740 ,  746  and outer surface  604  of bracket  602 . Meanwhile, as noted above, brush seals  614  provide a seal for cable passage area  608  to also prevent ingress of fluid or contaminants into cargo space  20  from the ambient environment. 
     Because cable  620  is spooled along spool  622 , cable  620  may move laterally during the opening or closing of door  16 . In order to accommodate this lateral movement, cable  620  is received within cable bushing  616 , which rolls freely within roller groove  612 . As cable  620  moves laterally during the spooling process, cable bushing  616  facilitates such lateral movement while the individual bristles of brush seals  614  continuously engage and substantially envelop cable  620  to maintain the sealing engagement therewith. 
     While this disclosure has been described as having exemplary designs, the present disclosure can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims.