Head curtains for dock shelters or dock seals are disclosed. An example dock apparatus disclosed herein includes a first weather barrier and a second weather barrier. The first and second weather barriers are positioned laterally of a doorway of a loading dock and compressible by a vehicle. The lateral weather barriers include inner surfaces that are to bulge toward each other in response to the vehicle compressing the lateral weather barriers. A head curtain is at least partially positioned between the lateral weather barriers and being engagable by the vehicle, the head curtain having a lateral stiffness such that in response to the vehicle engaging the head curtain and compressing the lateral weather barriers, the head curtain becomes pinched between the bulging inner surfaces to restrict a vertical movement of the curtain.

CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent arises from a continuation of U.S. patent application Ser. No. 13/656,212, filed on Oct. 19, 2012, entitled “Head Curtains for Dock Shelters or Dock Seals,” which is a continuation of U.S. patent application Ser. No. 12/821,973, filed on Jun. 23, 2010, now U.S. Pat. No. 8,327,587, which is a continuation-in-part of U.S. patent application Ser. No. 12/129,159, filed on May 29, 2008, now U.S. Pat. No. 8,042,307. U.S. patent application Ser. Nos. 13/656,212, 12/821,973 and 12/129,159 are incorporated herein by reference in their entireties. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The subject disclosure generally pertains to loading dock shelters and dock seal systems, and more specifically, to head curtains for such systems. 
       BACKGROUND 
       [0003]    Trucks having open rear cargo bays are typically backed into alignment with a loading dock or other doorway of a building to facilitate loading and unloading of the vehicle. A significant gap is usually created between the rear of the truck and the face of the building, which exposes the interiors of the building and the truck to the outside environment during loading and unloading. Such gaps can be at least partially sealed by installing either a loading dock shelter or a loading dock seal around the perimeter of the doorway. 
         [0004]    To seal or shelter the vehicle's rear vertical edges, dock shelters and dock seals usually have some type of lateral weather barrier installed along the side edges of the doorway. For dock shelters, the weather barrier usually shelters or seals against the vertical sides of the vehicle's trailer. An example of such an approach is shown in U.S. Pat. No. 3,322,132. Dock seals, on the other hand, usually have lateral weather barriers that are resiliently compressible for conformingly sealing against the vertical rear edges of the vehicle. An example of such an approach is shown in U.S. Pat. No. 5,125,196. Regardless of the structural design of the lateral weather barrier, the upper rear edge of the vehicle is often sealed or sheltered by a head curtain that drapes down onto the top of the vehicle as the vehicle backs into the dock. 
         [0005]    If the head curtain is extra long to accommodate a broad range of vehicle heights, the dock shelter or dock seal might include means for vertically retracting the curtain so that the curtain length is appropriate for the height of the particular vehicle at the dock. Thus, the curtain needs to be flexible not only for deflecting in reaction to the vehicle backing into the dock, but also for enabling the curtain to be retracted. Such flexibility or compliance, however, can weaken or hinder the curtain's ability to forcibly seal against the rear upper edge of the vehicle. Thus, instead of the curtain applying sealingly tight pressure against the upper edge of the vehicle, a pliable curtain readily deflects backwards toward the doorway of the dock. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a perspective view of an example dock apparatus described herein. 
           [0007]      FIG. 2  is an exploded perspective view of the example dock apparatus of  FIG. 1 . 
           [0008]      FIG. 3  is a cross-sectional view of the example dock apparatus of  FIG. 1  taken along line  3 - 3  of  FIG. 1 . 
           [0009]      FIG. 4  is a cross-sectional view similar to  FIG. 3  but showing a vehicle engaging the dock apparatus of  FIGS. 1 ,  2 , and  3 . 
           [0010]      FIG. 5  is a cross-sectional view of the example dock apparatus of  FIG. 1  taken along line  5 - 5  of  FIG. 1 . 
           [0011]      FIG. 6  is a cross-sectional view similar to  FIG. 5  but showing a head curtain assembly of the dock apparatus of  FIGS. 1-5  in a retracted position. 
           [0012]      FIG. 7  is a cross-sectional view similar to  FIG. 5  but showing another example dock apparatus described herein. 
           [0013]      FIG. 8  is a cross-sectional view of the example dock apparatus of  FIG. 7  with a vehicle engaging the example dock apparatus. 
           [0014]      FIG. 9  is a cross-sectional view similar to  FIG. 8  but showing a head curtain assembly of the example dock apparatus of  FIGS. 7 and 8  in a retracted position. 
           [0015]      FIG. 10  is a cross-section view similar to  FIG. 3  but showing another example dock apparatus described herein. 
           [0016]      FIG. 11  is a cross-section view similar to  FIG. 10  but showing a vehicle engaging the example dock apparatus of  FIG. 10 . 
           [0017]      FIG. 12  is a cross-sectional view similar to  FIG. 10  but showing another example dock apparatus described herein. 
           [0018]      FIG. 13  is a cross-sectional view of the example of  FIG. 12  but showing a vehicle engaging the example dock apparatus of  FIG. 12 . 
           [0019]      FIG. 14  is a cross-sectional view similar to  FIG. 10  but showing yet another example dock apparatus described herein. 
           [0020]      FIG. 15  is a cross-sectional view of the example of  FIG. 14  but showing a vehicle engaging the example dock apparatus of  FIG. 14 . 
           [0021]      FIG. 16  is a perspective view of another example dock apparatus described herein. 
           [0022]      FIG. 17  is a cross-sectional view of the example dock apparatus of  FIG. 16  taken along line  17 - 17  of  FIG. 16 . 
           [0023]      FIG. 18  is a cross-sectional view similar to  FIG. 17  but showing the example dock apparatus compressed by a vehicle. 
           [0024]      FIG. 19  is a cross-sectional view similar to  FIG. 5  but showing another example dock apparatus described herein. 
           [0025]      FIG. 20  is a cross-sectional view similar to  FIG. 19  but showing a curtain of the example dock apparatus of  FIG. 19  in a retracted position. 
           [0026]      FIG. 21  is a cross-sectional view similar to  FIG. 19  but showing another example dock apparatus described herein. 
           [0027]      FIG. 22  is a cross-sectional view similar to  FIG. 21  but showing a curtain of the example dock apparatus of  FIG. 21  in a retracted position. 
           [0028]      FIG. 23  is a cross-sectional view similar to  FIG. 19  but showing another example dock apparatus described herein. 
           [0029]      FIG. 24  is a cross-sectional view similar to  FIG. 23  but showing a curtain of the example dock apparatus of  FIG. 23  being engaged by a vehicle. 
           [0030]      FIG. 25  is a cross-sectional view similar to  FIG. 19  but illustrating another example dock apparatus described herein having an example gutter lip. 
           [0031]      FIG. 26  is a cross-sectional view similar to  FIG. 25  but showing another example gutter lip described herein. 
           [0032]      FIG. 27  is a perspective view of another example dock apparatus described herein. 
           [0033]      FIG. 28  is a cross-sectional view of the example dock apparatus of  FIG. 27  taken along line  28 - 28  of  FIG. 27 . 
           [0034]      FIG. 29  is a cross-sectional view similar to  FIG. 28  but showing a curtain of the example dock apparatus of  FIGS. 27 and 28  being deflected by a force. 
           [0035]      FIG. 30  is a perspective view of another example dock apparatus described herein. 
           [0036]      FIG. 31  is a cross-sectional view of the example dock apparatus of  FIG. 30  taken along line  31 - 31  of  FIG. 30 . 
           [0037]      FIG. 32  is a cross-sectional view similar to  FIG. 31  but showing the example dock apparatus of  FIG. 31  being engaged by a vehicle. 
           [0038]      FIG. 33  is a perspective view of another example dock apparatus described herein. 
           [0039]      FIG. 34  is a cross-sectional view of the example dock apparatus of  FIG. 33  taken along line  34 - 34  of  FIG. 33 . 
           [0040]      FIG. 35  is a cross-sectional view similar to  FIG. 34  but showing the example dock apparatus of  FIG. 33 and 34  being engaged by a vehicle. 
           [0041]      FIG. 36  is a perspective view of another example dock apparatus described herein. 
           [0042]      FIG. 37  is a cross-sectional view of the example dock apparatus of  FIG. 36  taken along line  37 - 37  of  FIG. 36 . 
           [0043]      FIG. 38  is a cross-sectional view similar to  FIG. 37  but showing the example dock apparatus of  FIG. 37  being engaged by a vehicle. 
           [0044]      FIG. 39  is a cross-sectional view similar to  FIG. 5  but showing another example dock apparatus described herein. 
           [0045]      FIG. 40  is a cross-sectional view similar to  FIG. 39  but showing the example dock apparatus of  FIG. 39  being engaged by a vehicle. 
       
    
    
     DETAILED DESCRIPTION 
       [0046]      FIGS. 1-6  show a loading dock apparatus  10  that helps seal and/or shelter the rear access opening of a truck/trailer vehicle  12  at a loading dock  14 . Dock  14  includes a doorway  16  in a wall  18  of a building. The dock apparatus  10  provides a barrier to weather and other elements as the vehicle's cargo is being loaded or unloaded at the doorway. To accommodate vehicles of various heights, dock apparatus  10  includes a head curtain assembly  20  with a retractable curtain  22  that seals along the vehicle's upper rear edge. 
         [0047]    To seal or shelter the vehicle's rear side edges, an upper sealing assembly illustratively in the form of a head curtain assembly  20  could be used with a dock shelter that includes lateral weather barriers or side panels that are relatively rigid and incompressible. Head curtain assembly  20 , however, is particularly suited for a dock seal  24  having lateral weather barriers in the form of resiliently compressible side pads  26 , thus assembly  20  will be described and illustrated with reference to dock seal  24 . 
         [0048]    Lateral edges  28  of curtain  22  preferably seal against the inner surfaces of side pads  26  (as shown in  FIG. 3 ) and/or seal against an inner surface  30  of a pair of flexible boots  32  that protect the upper ends of side pads  26 . A touch-and-hold fastener  27  (e.g., a fabric hook-and-loop fastener such as VELCRO™) can help seal edges  28  to surface  30 . As an alternative to conventional windstraps, an inner flexible panel  29  on boot  32  is coupled to wall  18  to help prevent vehicle  12  from pulling curtain assembly  20  away from wall  18  as vehicle  12  departs dock  14 . The connection  27  between edges  28  and surface  30  also helps prevent curtain assembly  20  from uncontrolled movement in strong winds when not engaged by a vehicle. To minimize wear, side pads  26  may include one or more cavities  31  ( FIG. 2 ) that reduce the compressive forces in certain localized areas, such as in the area behind boots  32 . 
         [0049]    When side pads  26  are compressed by the rear end of vehicle  12 , as shown in  FIG. 4 , pads  26  tend to bulge and push inward against the lateral edges  28 . To maintain a positive seal at edges  28 , a resiliently compressible foam panel  34  (covered by item  38 ) may be included to increase the rigidity or stiffness (e.g., horizontal rigidity) to curtain  22 . In addition to improved sealing at edges  28 , the curtain's increased horizontal stiffness in conjunction with pads  26  bulging inward firmly retains curtain  22  between pads  26 , and the bulging sections forcibly hold curtain  22  sealingly tight against the rear upper edge of vehicle  12 . 
         [0050]    To ensure that the horizontal stiffness does not hinder the curtain's ability to retract vertically from the position of  FIG. 5  to that of  FIG. 6 , foam panel  34  includes a series of compressed indentations  36  or bending creases that render panel  34  more flexible about a horizontal axis than about a vertical axis. Indentations  36  can be created or formed by sewing panel  34  to a pliable cover  38 , in which the sewing process produces a plurality of stitches  40  that holds the indentations in compression. Other methods of producing compressed indentations  36  include, but are not limited to, localized ultrasonic or heat sealing of cover  38  to foam panel  34  or localized ultrasonic or heat sealing of foam panel  34  to itself. Regardless of how indentations  36  are formed, maintaining foam panel  34  as a unitary piece, as opposed to a plurality of segments, simplifies manufacturability and provides a neat, clean appearance. 
         [0051]    The assembly of dock apparatus  10  is perhaps best understood with reference to  FIGS. 2 and 5 . Side pads  26  can be attached to wall  18  using any suitable means including, but not limited to, methods that are well known to those of ordinary skill in the art. To support foam panel  34 , curtain  22 , and an upper sheet  42  extending from curtain  22 , the head curtain assembly  20  of the illustrated example includes a resiliently crushable support panel  44  atop side pads  26 . In some examples, support panel  44  comprises a semi-rigid polymeric sheet  46  (e.g., polyethylene, polypropylene, fiberglass, etc.) encased within a pliable cover  48 . The semi-rigidity panel  44  makes it more impactable and durable than other conventional frameworks that are substantially rigid and readily damaged by vehicular impact. Panel  44  may be designed so that it could be impacted by a vehicle and compressed all the way to the loading dock wall without damage—a function not found in a conventional rigid frame. 
         [0052]    A touch-and-hold fastener  50  (e.g., a fabric hook-and-loop fastener such as VELCRO™) can be used to contain sheet  46  within cover  48 . A resiliently flexible horizontal elongate polymeric stay  52  (e.g., rod, bar, tube, etc. made of polyethylene, polypropylene, fiberglass, etc.) can be attached to panel  44  to provide support panel  44  with additional stiffness. Stay  52  can be held within a sleeve illustratively depicted as a loop of material  54  so that stay  52  can be readily replaced if necessary. A tube  56  or bar anchored to wall  18  via a series of fasteners  58  can be used for attaching an upper flange of support panel  44  to wall  18 . 
         [0053]    To provide head curtain assembly  20  with various components that can be readily replaced individually, touch-and-hold fasteners can be used throughout the assembly. A touch-and-hold fastener  60 , for example, can attach an upper end of the creased foam panel's cover  38  to upper sheet  42 , and another touch-and-hold fastener  62  can connect the lower end of cover  38  to a lip  64  extending from curtain  22 , thereby removably attaching foam panel  34  to curtain  22 . An additional touch-and-hold fastener  66  can removably attach cover  38  to support panel  44 . Other touch-and-hold fasteners  68  and/or  70  can fasten upper sheet  42  to support panel  44  and/or to a flap  72  anchored to wall  18 . Flexible boots  32  that help protect the upper ends of side pads  26  can also be removably attached using a touch-and-hold fastener  74  so that boots  32  are readily replaceable. 
         [0054]    A resiliently flexible horizontal polymeric stay  76  (e.g., rod, bar, tube, etc. made of polyethylene, polypropylene, fiberglass, etc.) can be attached to the lower end of curtain  22  to provide curtain  22  with additional horizontal stiffness. Stay  76  can be held within a loop of material  78  so that stay  76  can be readily replaced if necessary. Stay  76  with or without additional weight can also help hold curtain  22  taut (e.g., vertically taut) so that curtain  22  can lie relatively flat when fully extended, as shown in  FIG. 5 . 
         [0055]    To raise curtain  22  from its position of  FIG. 5  to that of  FIG. 6 , a pull cord  80  (i.e., any pliable elongate member, such as a rope, strap, chain, etc.) attached to a lower end of curtain  22  can be threaded through a series of pulleys or eyelets  82  with one end  84  of cord  80  available for an operator (e.g., a manual operator or a mechanical operator)) to pull cord  80  so as to raise curtain  22 . If cord  80  is manually pulled, curtain  22  can be held at a raised position by temporarily securing cord  80  to a cleat  86  anchored to wall  18 , as shown in  FIG. 6 . 
         [0056]    In another example,  FIGS. 7 ,  8  and  9  illustrate another example dock apparatus  88  having a head curtain assembly  90 . In this example, dock apparatus  88  comprises a front curtain  92  suspended between two lateral weather barriers  26 . To accommodate vehicles of various heights, a pliable elongate member  94  (e.g., a pull cord, rope, strap, chain, etc.) is coupled to a distal end  96  of front curtain  92  to selectively position distal end  96  between a lowered position ( FIG. 7 ) and a raised position ( FIG. 9 ). To adjust the height of curtain  92 , elongate member  94  can be actuated by a motorized hoist  98  or manually pulled and released. 
         [0057]    To ensure that front curtain  92  seals firmly against the rear of vehicle  12 , a stiffener  100  is installed behind front curtain  92 . Stiffener  100  is less flexible than front curtain  92  and is a horizontally elongate member that extends between the two lateral weather barriers  26  such that stiffener  100  becomes compressed horizontally between the two lateral weather barriers  26  as the lateral weather barriers are compressed by vehicle  12 . Although the actual structure of stiffener  100  may vary, in some cases, stiffener  100  comprises a resilient foam cylinder  102  reinforced by a plastic tube  104 . For additional stiffness, a resiliently flexible rod  106  can be attached to distal end  96  of front curtain  92 . 
         [0058]    In some examples, curtain assembly  90  includes a rear curtain  108  that helps contain and protect stiffener  100  and a lower section of elongate member  94 . The lower end of rear curtain  108  connects to distal end  96  of front curtain  92 . An upper end  110  of rear curtain  108  connects to the back side of front curtain  92  with one or more openings  112  for feeding elongate member  94  from the interior space between curtains  92  and  108  and externally mounted hoist  98  or cleat  86  ( FIG. 5 ). 
         [0059]    To help prevent stiffener  100  from escaping between curtains  92  and  108 , a pliable retention member  114  may be used to attach stiffener  100  to an upper or lower end of curtain  92  and/or curtain  108 . In some cases, retention member  114  is a sheet of pliable material that extends about the full length of stiffener  100 . 
         [0060]    Operation of dock apparatus  88  could begin with apparatus  88  in the lowered position, as shown in  FIG. 7 . Vehicle  12  backs into the dock and compresses the two lateral weather barriers  26 , as shown in  FIG. 8 . In this position, lateral weather barriers  26  bulge inward toward each other (similar to  FIG. 4 ), thereby holding stiffener  100  firmly up against the rear of vehicle  12 . To prevent front curtain  92  from obstructing the rear access opening of vehicle  12 , pliable elongate member  94  can be shorted to pull distal end  96  upward to the raised position of  FIG. 9 . As pliable elongate member  94  lifts distal end  96 , front curtain  92  cradles and lifts stiffener  100 , and rear curtain  108  folds over onto itself 
         [0061]    Once in the configuration of  FIG. 9 , bulging sections of lateral weather barriers  26  pressing stiffener  100  up against vehicle  12  holds curtain assembly  90  in the raised position, perhaps even if elongate member  100  is released (e.g., disengaged from a cleat or released by winch  98 ). However, when vehicle  12  departs while elongate member  94  is slack, curtain assembly  90  can freely and automatically fall back to the lowered position of  FIG. 7 . 
         [0062]    If hoist  98  is used for raising curtain assembly  90  (as opposed to the manual option of  FIGS. 5 and 6 ), the electrical current drawn by the hoist  98  can be sensed and used as a means for automatically stopping the lift of curtain  92 . Lifting stiffener  100  from the lowered position of  FIG. 8  to the raised position of  FIG. 9  generally requires less current than it takes to lift stiffener  100  up and over the upper rear edge of vehicle  12 , i.e., above and beyond the stiffener's position of  FIG. 9 . Such increase in current drawn by the hoist  98  could be used as a signal for stopping hoist  98  when stiffener  100  reaches its properly raised position. The operation of hoist  98  could also be controlled in concert with other dock-related equipment including, but not limited to, vehicle restraints, dock levelers, doors, vehicle sensors, etc. 
         [0063]    To enhance a lateral weather barrier's ability to firmly hold a head curtain (e.g., including, but not limited to curtain or curtain assemblies  20 ,  90  or  120 ) up against the rear of vehicle  12 , a lateral weather barrier can be provided with a flexible inner surface that is shaped such that the surface bulges in a particularly advantageous manner. Examples of such surfaces are illustrated in  FIGS. 10-15 . The surfaces in these examples are part of a boot, wherein the boot is considered as being part of a lateral weather barrier (i.e., the lateral weather barrier includes the boot). Such functionality was not possible in previous systems that did not have adequate lateral stiffness to be held in place by the inwardly-bulging lateral weather barriers  26 . 
         [0064]    In  FIGS. 10 and 11 , two inner surfaces  116  of the boots of lateral weather barriers  118  allow some lateral clearance or light interference with curtain  120  when vehicle  12  is spaced apart from weather barriers  118 , as shown in  FIG. 10 . Under compression by vehicle  12 , however, surfaces  116  bulge toward each other to hold curtain  120  firmly against vehicle  12 , as shown in  FIG. 11 . Surfaces  116  can be provided by a resiliently flexible panel similar to panel  29  of  FIG. 2 . 
         [0065]    In  FIGS. 12 and 13 , two inner surfaces  122  of the boots of lateral weather barriers  118  allow some lateral clearance or light interference with curtain  120  when vehicle  12  is spaced apart from weather barriers  118 , as shown in  FIG. 12 . Under compression by vehicle  12 , however, surfaces  122  bulge toward each other to hold curtain  120  firmly against vehicle  12 , as shown in  FIG. 13 . Surfaces  122 , in some examples, are provided by a resiliently flexible panel sewn or otherwise attached to a panel similar to panel  29  of  FIG. 2 . Such resiliently flexible panels enhance the pinching action of surfaces  122  against the lateral edges of curtain  120 . 
         [0066]    In  FIGS. 14 and 15 , two inner surfaces  124  of the boots of lateral weather barriers  118  allow some lateral clearance or light interference with curtain  120  when vehicle  12  is spaced apart from weather barriers  118 , as shown in  FIG. 14 . Under compression by vehicle  12 , however, surfaces  124  bulge toward each other to hold curtain  120  firmly against vehicle  12 , as shown in  FIG. 15 . Surfaces  124  can be provided by a resiliently flexible panel sewn or otherwise attached to a panel similar to panel  29  of  FIG. 2 . 
         [0067]    It should be noted that existing dock seals with a compressible foam head pad can be retrofitted with the head curtain assemblies disclosed herein. In replacing an existing head pad, however, it may be beneficial to add a short vertical extension onto the existing side pads so that the new head curtain assembly is at sufficient height properly service vehicles of varying heights. Such an extension could be made similar to lateral weather barrier  26 , only significantly shorter. The extension can include cavity  31  to reduce compressive forces at the boot. 
         [0068]    In the example of  FIGS. 16-18 , a loading dock apparatus  130  includes a stiffener  132  at each upper corner to help ensure that upon vehicle  12  compressing two lateral weather barriers  26 , the barriers  26  bulge inward toward each other to seal against the lateral edges  28  of front head curtain  22 . In this example, each of the lateral weather barriers  26  are shown as resiliently compressible side pads, wherein each pad comprises a foam core contained within a pliable cover.  FIG. 17  shows dock apparatus  130  prior to being compressed by vehicle  12 , and  FIG. 18  shows apparatus  130  in compression or being engaged by the vehicle  12 . 
         [0069]    In some examples, the length of dimension of stiffener  132  (e.g., vertically elongate) is shorter than the lengths of pads  26 , and is made of a stiffer material (e.g., fiberglass) than that of pad  26  and/or boot  32 . In the illustrated example, each stiffener  132  is disposed in the vicinity of upper sealing member (e.g., front curtain  22 ) and positioned to place the two pads  26  between the two stiffeners  132 . In this position, stiffeners  132  resists the pad's tendency to bulge away from each other, thus the pads  26  are more inclined to bulge inward to press its inner surfaces  134  sealingly tight against the curtain's lateral edges  28 . Although stiffeners  132  enhance or increase the amount of side pad's inward bulging, a small portion of pad  26  might still bulge into an area  136  that is between wall  18  and stiffeners  132 . 
         [0070]    In the example of  FIGS. 19 and 20 , a dock apparatus  138  comprises a retractable front curtain  140  suspended from an overhead support panel  142 . Curtain  140  is schematically illustrated to represent any retractable single sheet of material, multi-sheet of material, foam panel, pliable cover, and/or various combinations thereof. Curtain  140 , for example, may include one or more of the construction details of the curtain shown in  FIG. 5  or  7 . Curtain  140 , however, does not utilize retention member  114  ( FIG. 7 ) fastened to a roller  142  (e.g., stiffener  100  of  FIG. 7 ). Instead, roller  142  is cradled in a sling  144  provided by curtain  140  with the support of pliable elongate member  94 . 
         [0071]    To retract curtain  140 , elongate member  94  pulls a lower edge  146  of curtain  144  from a lowered position ( FIG. 19 ) to a raised position ( FIG. 20 ). As lower edge  146  moves from its lowered position to its raised position, lower edge  146  rises between roller  142  and an imaginary plane  148  defined by wall  18 . 
         [0072]    In another example, shown in  FIGS. 21 and 22 , elongate member  94  retracts a curtain  140 ′ in a somewhat reversed manner compared to the curtain  140  of  FIGS. 19 and 20 . As lower edge  146  moves between a lowered position and a raised position, roller  146  at some point becomes interposed between lower edge  146  and wall plane  148 . The arrangement of  FIGS. 19 and 20  can make it easier to retract curtain  140  with less effort, but the arrangement of  FIGS. 21 and 22  can pull curtain  140 ′ more tightly against a rear edge of vehicle  12  for better sealing. 
         [0073]    In another example, shown in  FIGS. 23 and 24 , a dock apparatus  150  comprises a front curtain  152  suspended from an overhead support panel  154 . Curtain  152  is schematically illustrated to represent any retractable single sheet of material, multi-sheet of material, foam panel, pliable cover, and/or various combinations thereof. Curtain  152 , for example, may include one or more of the construction details of the curtain shown in  FIG. 5  or  7 . In this example, support panel  154  is relatively stiff to help support the weight of curtain  152  yet is resiliently flexible to bend between a relaxed position ( FIG. 23 ) and a strained position ( FIG. 24 ). 
         [0074]    In this example, an anchor bar  156  (e.g., structural angle, structural channel, tube  56 , etc.) is firmly attached to wall  18  and support panel  154  to help hold panel  154  at its relaxed position and to help panel  154  resist deflecting to its strained position. As vehicle  12  backs into or otherwise engages curtain  152 , the friction between curtain  152  and vehicle  12  pulls curtain  152  downward, which pulls a distal edge  158  of support panel  154  downward toward (e.g., closer) to wall  18 . As this occurs, the deflection resistance of support panel  154  urges curtain  152  sealingly tight up against a rear edge of vehicle  12 . 
         [0075]    In some examples, to further support panel  154  at its relaxed position of  FIG. 23 , dock apparatus  150  can be used in conjunction with a resiliently flexible horizontally elongate stay (e.g., stay  52  of  FIG. 5 ) resting atop two lateral weather barriers (e.g., side pad  26  of  FIG. 5 ). 
         [0076]    In some examples, as shown in  FIG. 25 , a dock apparatus  160  includes a gutter lip  162  extending along and protruding upward from a distal edge  164  of a support panel  166 . Lip  162  helps deflect water that might drain down across the upper surface of panel  166 , from a proximal edge  168  of panel  166  to distal edge  164 , thus inhibiting the drainage from dripping between the rear of vehicle  12  and doorway  16 . In some examples, as shown in  FIG. 25 , lip  162  is an integral extension of panel  166 , whereby lip  162  and panel  166  comprise a unitary piece. In other examples, as shown in  FIG. 26 , a gutter lip  170  is in the form of a resiliently flexible piece  172  contained within a pliable cover  174 . Pliable cover  174 , in some examples, also covers a support panel  176 . 
         [0077]    In some cases, the upper rear edge of a vehicle includes a rearward protrusion, such as hardware associated with a rear door latch. To help prevent such a protrusion from poking through a front curtain or front pad of a dock seal or shelter, an example dock apparatus  178 , shown in  FIGS. 27-29 , includes a retractable front curtain  180  suspended from a support panel  182 . Curtain  180  includes an inner region  184  that has a greater penetrating force tolerance than that of an outer peripheral region  186  of the curtain  180 . A region having “greater penetrating force tolerance” means that for a given protrusion pressing with a given force (once or repeatedly) against the region, the region will experience less permanent damage than another region subject to the same pressing force.  FIG. 28  shows curtain  180  without being subjected to a penetrating force, and  FIG. 29  shows curtain  180  reacting to a penetrating force  188  from a vehicle. 
         [0078]    To achieve greater penetrating force tolerance, in some examples, front curtain  180  includes two slits  190  that flank inner region  184 . Slits  190  provide inner region  184  with greater flexibility or more freedom to flex in reaction to penetrating force  188 , as slits  190  make inner region  184  less constrained by outer region  186 . To prevent air and water from leaking through slits  190 , an expansion joint  192  covers each slit  190 . In some examples, expansion joint  192  is a web of flexible material with one edge  194  folded back onto itself with the entire perimeter of the web being sewn or otherwise attached to the back side of curtain  180 . 
         [0079]    In some examples, as shown in  FIGS. 30-32 , a series or plurality of overlapping pleats  196  cover inner region  184  of curtain  180  to provide several benefits. Pleats  196  provide curtain  180  with even greater penetrating force tolerance, greater wear resistance, and/or improved sealing against an upper surface  198  of vehicle  12 . As vehicle  12  backs into curtain  180 , pleats  196  deflect as shown in  FIG. 32  to press sealingly tight downward against the vehicle's upper surface  198 . In other examples, pleats  196  can be added to other example curtains and/or header pads (e.g., the curtains  32 ,  92 ,  12 ,  140 ,  140 ′, and  152  described herein), even the curtains or head pads without additional features (e.g., slits) that make the curtains and/or header pads more tolerant of penetrating forces. 
         [0080]    In some examples, as shown in  FIGS. 33-35 , a dock apparatus  200  includes a curtain  202  with a series of flexible loops  204  instead of pleats  196 . Loops  204 , in some examples, are made of a flexible material similar to the material of curtain  202  and can be sewn or otherwise attached to the front face of curtain  202  or attached to the front face of a foam header pad via any other suitable fastener such as, for example, Velcro®, adhesive, etc. Loops  204  provide the front face of curtain  202  with more compliance to seal against vehicle  12 . Such compliance can also make curtain  202  more tolerant of rearward protrusions on vehicle  12 . 
         [0081]    In some examples, shown in  FIGS. 36-38 , a dock apparatus  206  includes a retractable curtain  208  with a series of pleats  210  overlapping a series of loops  212 . In this example, loops  212  are more triangular than U-shaped or bell-shaped, and loops  212  bias pleats  210  in a generally outward projection. As vehicle  12  backs into curtain  208 , loops  212  urge pleats  210  down into and against vehicle  12 . Loops  212  in combination with pleats  210  not only provide the front face of curtain  208  with more compliance to seal against vehicle  12  but also provides curtain  208  with more tolerance of rearward protrusions on vehicle  12 . 
         [0082]    In some examples, shown in  FIGS. 39 and 40 , a dock apparatus  214  comprises a resiliently compressible header  216  that is substantially horizontally elongate and mounted in proximity with an overhead edge  218  of doorway  16 . In this example, header  216  comprises a resiliently compressible foam core  220  contained within a pliable cover  222 . A cavity  224  (e.g., a collapsible cavity) defined by foam core  220  renders header  216  more tolerant of rearward protrusions on vehicle  12 . In some examples, core  220  is a single piece of foam defining cavity  224 , and in other examples, the header's foam core is comprised of multiple foam pieces. In the illustrated example, the header's foam core  220  is comprised of two foam pieces  220   a  and  220   b.    
         [0083]    To provide header  216  with greater penetrating force tolerance, greater wear resistance, and improved sealing against upper surface  198  of vehicle  12 , header  216  includes a plurality of pleats  226  overlying cover  222  such that cavity  224  is between foam core  220  and pleats  226 . As vehicle  12  backs into header  216 , pleats  226  deflect as shown in  FIG. 40  to press sealingly tight downward against the vehicle's upper surface  198 . To seal along the rear vertical edges of vehicle  12 , some examples of dock apparatus  214  also include a pair of resiliently compressible weather barriers  26  that are installed along the lateral vertical edges of doorway  16 . 
         [0084]    While plurality of pleats  226  may be particularly effective at sealing against vehicle  12  when pleats  226  are used in conjunction with cavity  224 , plurality of pleats  226  may also provide an effective seal against vehicle's upper surface  198 , even without cavity  224 . In a header without foam piece  220   b  and cavity  224 , cover  222  would tightly overlay foam core  220  and a plurality of pleats  226  would overlay a front face of cover  222 . As vehicle  12  backs into header  216 , lower portion of foam core  220  compresses, pushing pleats  226  out and causing pleats  226  to deflect and press sealingly tight downward against the vehicle's upper surface  198 . In this manner, pleats  226  effectively cover any gaps that may otherwise exist between cover  222  and vehicle  12  and divert rain water away from the header  216 . Typically, pleats are often used exclusively on loading dock side pads (e.g., side pads  26  of  FIG. 1 ) to provide increased wear resistance to the covers of the side pads (lateral edges of a vehicle rub against the side pads as the vehicle is loaded or unloaded), but the current example utilizes pleats  226  on header  216  as sealing and rain diversion devices. The pleats  226  on header  216  may span the entire length of the header (spanning substantially the entire gap between side pads  26 ) to provide effecting sealing and rain diversion across the entire width of vehicle  12 . 
         [0085]    At least some of the aforementioned examples include one or more features and/or benefits including, but not limited to, the following: 
         [0086]    In some examples, a dock apparatus includes a retractable head curtain that is more flexible about a horizontal axis than a vertical axis. 
         [0087]    In some examples, the head curtain is supported by a resiliently compressible, creased foam panel. 
         [0088]    In some examples, the creases in the foam panel are created by sewing the foam panel to a pliable cover using a series of horizontal stitch lines. 
         [0089]    In some examples, the foam panel is removably attached to the head curtain. 
         [0090]    In some examples, the head curtain is removably attached to a support panel. 
         [0091]    In some examples, the support panel is stiffened by a readily replaceable fiberglass stay. 
         [0092]    In some examples, the lower end of the head curtain is stiffened by a readily replaceable fiberglass stay. 
         [0093]    In some examples, the dock apparatus includes a pair of protective boots that are readily replaceable. 
         [0094]    Although certain example methods, apparatus, and articles of manufacture have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus, and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.