Patent Publication Number: US-9416589-B2

Title: Deformable guide for a rollable door, rollable door guiding system having a deformable guide, and door using the same

Description:
TECHNICAL FIELD 
     The present disclosure relates to the field of door systems. More specifically, the present disclosure relates to a deformable guide for a rollable door, to a guiding system for a rollable door, the guiding system having a deformable guide, and to a door using the deformable guide. 
     BACKGROUND 
     Roll-up doors offer wide flexibility in terms of sizes and the capability of undergoing large numbers of fast opening and closing cycles in a single day. They are used, predominantly in commercial and industrial applications. These doors usually comprise a large curtain made of a flexible material, for example rubber, supported by guides on each side of a door frame. 
     Because roll-up doors may be very large, they may withstand excessive wind loads leading to ripping or tearing of the curtain, or to breakage of the guides or door frame. Also, as trucks and like vehicles enter and leave commercial or industrial buildings through those doors, accidents are bound to happen and curtains may be hit, resulting in the tearing of a curtain or damage to door guides or frames. 
     Therefore, there is a need for a door system capable of limiting damages to buildings and to the door system itself under excessive load situations. 
     SUMMARY 
     According to the present disclosure, there is provided a deformable guide for a rollable door. The guide comprises two wall portions. A first one of the wall portions defines a longitudinal edge while a second one of the wall portions defines an inner longitudinal planar face. Together, the inner longitudinal planar face and the longitudinal edge define a longitudinal slot. The guide is configured to receive, via the longitudinal slot, a longitudinal end section of a rollable door side strip, the inner longitudinal planar face of the guide providing a mating surface for a planar surface of the side strip. The guide is also configured to maintain, within the guide, a longitudinal rib of the longitudinal end section of the side strip and to release the side strip by widening of the longitudinal slot upon application on the side strip of a force exceeding a predetermined threshold. 
     According to the present disclosure, there is also provided a guiding system for a rollable door. The guiding system comprises a deformable guide and a side strip. The deformable guide has two wall portions. A first one of the wall portions defines a longitudinal edge while a second one of the wall portions define an inner longitudinal planar face. Together, the inner longitudinal planar face and the longitudinal edge define a longitudinal slot. The side strip is configured for attachment to a curtain of the rollable door. The side strip has a longitudinal end section insertable into the guide via the longitudinal slot. The side strip also has a planar surface for mating with the inner longitudinal planar face. The longitudinal end section also comprises at least one longitudinal rib for maintaining the side strip within the guide. The guide is configured to release the side strip by widening of the longitudinal slot upon application on the side strip of a force exceeding a predetermined threshold. 
     The present disclosure further relates to a door. The door comprises a flexible door curtain and a guiding system. The guiding system is configured for attachment to a door frame and comprises a deformable guide and a side strip. The deformable guide has two wall portions. A first one of the wall portions defines a longitudinal edge while a second one of the wall portions defines an inner longitudinal planar face. Together, the inner longitudinal planar face and the longitudinal edge define a longitudinal slot. The side strip is configured for attachment to the door curtain. The side strip has a longitudinal end section insertable into the guide via the longitudinal slot, and a planar surface for mating with the inner longitudinal planar face. The longitudinal end section also comprises a longitudinal rib for maintaining the side strip within the guide. The guide is configured to release the side strip by widening of the longitudinal slot upon application on the door curtain of a force exceeding a predetermined threshold. 
     The foregoing and other features will become more apparent upon reading of the following non-restrictive description of illustrative embodiments thereof, given by way of example only with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the disclosure will be described by way of example only with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective, partial view of a roll-up door system; 
         FIG. 2  is a schematic cross-sectional view showing a structure of a roll-up door curtain; 
         FIG. 3  is a top cross-sectional view of a vertical side strip, part of the roll-up door system of  FIG. 1 ; 
         FIG. 4  is a perspective view of the vertical side strip of  FIG. 3  as seen from one side; 
         FIG. 5  is a perspective view of the vertical side strip of  FIG. 3  as seen from an opposite side; 
         FIG. 6  is a top cross-sectional view of a vertical guide for a roll-up door curtain; 
         FIG. 7  shows an interaction of the vertical side strip of  FIG. 3  with the vertical guide of  FIG. 6 ; 
         FIG. 8  shows an interaction of the vertical side strip of  FIG. 3  with a first variant of the vertical guide; 
         FIG. 9 a    is a top cross-sectional view of a second variant of the vertical guide; 
         FIG. 9 b    is a top cross-sectional view of one portion of the vertical guide of  FIG. 9 a   ; and 
         FIG. 9 c    is a top cross-sectional view of another portion of the vertical guide of  FIG. 9   a.    
     
    
    
     DETAILED DESCRIPTION 
     Like numerals represent like features on the various drawings. 
     Various aspects of the present disclosure generally address one or more of the problems of damages to buildings and to rollable door systems under excessive wind load on rollable door curtains or resulting from accidental collisions of vehicles on such curtains. 
     Though rollable doors may be made to operate in various planes, the following description will refer mainly to roll-up doors, which are doors that open by moving their curtains upwards. The present disclosure applies to other rollable doors and reference to “roll-up doors” is made for illustration purposes only. 
     Referring now to the drawings,  FIG. 1  is perspective, partial view of a roll-up door system. A roll-up door system, generally shown at  1 , comprises a flexible curtain  2 , a deformable vertical guide  3  that is mountable on a doorway frame  4 , a vertical side strip  5  for connecting the curtain  2  to the vertical guide  3 , and a main roller  6  for rolling the curtain  2 . The roll-up door system  1  may also comprise a plate such as  7  for holding the roller  6  at both ends, an idler roller  8 , and an iron angle  10  connected to the curtain  2  at its bottom, as are well-known in the art. Of course, realizations of the roll-up door system  1  may comprise two opposed vertical guides  3  and two opposed vertical side strips  5  on either sides of the curtain  2 , with the main roller  6  extending between two plates  7  positioned atop of each vertical guides  3 . Likewise, the idler roller  8 , the iron angle  10  may extend along a width of the doorway. Later Figures will illustrate interaction of the vertical side strip  5  with the vertical guide  3  to form a guiding system for the roll-up door. 
     The flexible curtain  2  of the roll-up door system  1  may be made, for example, of rubber material, recycled rubber material, synthetic rubber material, flexible plastic material or fabric material suitable or capable of closing the doorway.  FIG. 2  is a schematic cross-sectional view showing a structure of a roll-up door curtain. In an example of realization, the curtain  2  may be a laminated curtain comprising a first layer  32  of flexible recycled rubber material or similar material and a second layer  34  of the same material. Interposed between the first  32  and second  34  layers may be a reinforcing layer  36  of fabric material that may be made, for example, of woven or non-woven fiberglass or nylon fibers. The three (3) layers  32 ,  34  and  36  are appropriately adhered to each other using a suitable adhesive to form the laminated curtain  2 . Suitable adhesives may comprise, without limitation, silicone, styrene, polyurethane, isocyanate, organic adhesives, polymers, acrylics, epoxies, hot melts, and the like. 
     The curtain  2  may also be a one-layer curtain made of, for example, flexible rubber material, flexible recycled rubber material, flexible synthetic rubber material, flexible plastic material or flexible fabric material. 
       FIG. 3  is a top cross-sectional view of a vertical side strip, part of the roll-up door system of  FIG. 1 . As illustrated in  FIG. 3 , the vertical side strip  5  is mounted to a side of the curtain  2 . The vertical side strip  5  may be made of the same material as the curtain  2 , for example flexible rubber material, flexible recycled rubber material, flexible synthetic rubber material, flexible plastic material or flexible fabric material. The vertical side strip  5  may also be laminated in a manner similar to the curtain  2 . The vertical side strip  5  may also be extruded or otherwise shaped to form the cross section illustrated in  FIG. 3 . Without limitation, an overall length “L” of the vertical side strip  5  can vary from 3 to 12 inches and an overall thickness “T” of the vertical side strip  5  can vary from 1¼ in to 3 inches. Of course, dimensions will vary according to specific applications and according to an overall size of the roll-up door. 
     More specifically, the vertical side strip  5  comprises a proximate longitudinal portion  12 , which is U-shaped in cross section, and a distal longitudinal end-section  20  for sliding into the vertical guide  3  of  FIG. 1 . A link  19  connects the proximate longitudinal portion  12  to the longitudinal end section  20  along their respective lengths. 
     The proximate longitudinal U-shaped portion  12  defines first and second spaced apart, parallel walls  14  and  16 . Sizes, thicknesses and configurations of the vertical side strip  5  may depend on the application and on materials used. As non-limiting examples, the proximate longitudinal portion  12  may be between 2 and 12 inches long, the parallel walls  14  and  16  may have thicknesses between ¼ and ¼ of an inch, the distal longitudinal end-section  20  and the shifted wall section  24  may also have thicknesses between ¼ and ¼ of an inch. 
     As illustrated in  FIG. 3 , the vertical side strip  5  is mounted on a corresponding side edge  18  of the curtain  2  by inserting the side edge  18  of the curtain  2  in between the walls  14  and  16  of the longitudinal U-shaped portion  12 , and by adhering the opposite longitudinal faces of the side edge  18  to respective inner faces of the walls  14  and  16  of the longitudinal U-shaped portion  12 . Adhesives suitable for that purpose may comprise, without limitation, silicone, styrene, polyurethane, isocyanate, organic adhesives polymers, acrylics, epoxies, hot melts, and the like. 
     The longitudinal end section  20  of the vertical side strip  5  comprises, on one side a first longitudinal rib  22  and, on another side, a shifted wall section  24 . 
     The shifted wall section  24  forms a free edge  26  of the vertical side strip  5 . The shifted wall section  24  also defines a second longitudinal rib  28  with a sloping wall  30  on the corresponding side of the vertical side strip  5 . 
     The first longitudinal rib  22  is generally trapezoidal in cross section and is positioned on the side of the vertical side strip  5  opposite the second longitudinal rib  28 . Also, the first longitudinal rib  22  is laterally shifted inwardly with respect to the second longitudinal rib  28 . 
       FIG. 4  is a perspective view of the vertical side strip of  FIG. 3  as seen from one side.  FIG. 5  is a perspective view of the vertical side strip of  FIG. 3  as seen from an opposite side. Referring at once to  FIGS. 4 and 5 , a layer  40  of plastic slippery and wear-resistant material may be embedded into the surface of the second longitudinal rib  28  and sloping wall  30  to facilitate sliding of the vertical side strip  5  into the vertical guide  3 . In the same manner, a layer  42  of plastic slippery and wear-resistant material may be embedded into the surface of the generally trapezoidal first longitudinal rib  22 . As a non-limitative example, the plastic slippery and wear-resistant material may comprise Teflon™. 
       FIG. 6  is a top cross-sectional view of a vertical guide for a roll-up door curtain. According to a first embodiment, the vertical guide  3  is an extruded one-piece vertical guide, which may be made of metal, for example aluminum. The use of any other suitable metal or material can also be contemplated. The vertical guide  3  is deformable, either resiliably or plastically, as will be explained in details herein below. 
     As illustrated in  FIG. 6 , the vertical guide  3  comprises a longitudinal rear base wall  50 . Holes such as  52 , optionally threaded, are provided to allow installation of the vertical guide  3  on the frame  4  of a doorway using bolts (not shown). A pair of longitudinal, spaced apart and parallel or substantially parallel wall sections  54  and  56  extends from the longitudinal base wall  50  to define a cavity  58  between the wall sections  54  and  56 . In a particular embodiment, the wall section  54  has a thinner cross-section  55  when compared to a cross-section  57  of the wall section  56 . Consequently, while both wall sections  54  and  56  are deformable, the wall section  54  tends to flex with greater amplitude than the wall section  56  when a force is applied to the vertical guide  3 . 
     The vertical guide  3  is sized to accommodate dimensions of the vertical side strip  5 . Without limitation, an overall width “W” of the vertical guide  3  can vary from 3 to 24 inches, an overall depth “D” of the vertical guide  3  can vary from 2 to 12 inches, and the cross-sections  55  and  57  can vary from ⅜ to 1 inch. Of course, dimensions will vary according to structural requirements, to specific applications and to an overall size of the roll-up door. 
     On the front side thereof, the wall portion  56  is bent a first time at 90° (see  60 ) to form a longitudinal front wall portion  62 . The wall portion  56  is bent a second time at 90° to define a wall portion  64  parallel to the wall portions  54  and  56  and defining an inner longitudinal planar face  66 , parallel to both the wall portions  54  and  56 , and an inner longitudinal edge  68  at an extremity of the inner longitudinal planar face  66 . 
     One the front side thereof, the wall portion  54  is bent inwardly at an obtuse angle (see  70 ) to form an angular longitudinal wall  72  with a free longitudinal edge  74 . 
     When assembled, the vertical side strip  5  attached to the curtain  2  is movable or slidable longitudinally in the vertical guide  3  as the curtain  2  is raised or lowered during use thereof. Together, the vertical side strip  5  and the vertical guide  3  form a guiding system for a roll-up door having the curtain  2 . For this, the longitudinal edge  74  defines with the inner longitudinal planar face  66  a longitudinal slot  76  to receive the link  19  of the vertical side strip  5  between the proximate U-shaped longitudinal portion  12  and the first longitudinal rib  22 . Embodiments of the guiding system may comprise two opposed vertical guides  3  on either sides of the curtain  2 . In such cases, two symmetrically mounted vertical side strips  5  attached to opposed vertical edges of the curtain  2  move or slide within corresponding vertical guides  3 . 
     Though as shown on  FIG. 6 , the wall sections  54  and  56  are substantially parallel, other configurations are contemplated. For example, one or both of the wall sections  54  and  56  may be curved. Alternatively, the overall depth “D” may be larger at one end, for example at the end having the threaded holes  52 , and narrower at an opposite end, for example at the end having the longitudinal slot  76 . An internal shape of the cavity  58  is inconsequential, inasmuch as it is sufficient to accommodate insertion of the distal longitudinal end-section  20  of the vertical side strip  5 . 
     The vertical guide  3  is configured to receive, via the longitudinal slot  76 , a longitudinal end section of a roll-up door vertical side strip such as the vertical side strip  5  of  FIG. 3 . A planar surface of the vertical side strip may then slide on the inner longitudinal planar face  66  of the vertical guide  3 . The vertical guide  3  is also configured to internally maintain a longitudinal rib of the longitudinal end section of the roll-up door vertical side strip. The vertical guide  3  will release the vertical side strip by widening of the longitudinal slot  76  upon application on the vertical side strip of a force exceeding a predetermined threshold. As a non-limiting example, the predetermined threshold may ensure release of the vertical side strip upon a wind load of 144 km/hour, or 0.96 kpa. 
       FIG. 7  shows an interaction of the vertical side strip of  FIG. 3  with the vertical guide of  FIG. 6 . Some numeral indices of  FIGS. 3 and 6  are not reproduced on  FIG. 7  for readability purposes. The vertical side strip  5  defines a first planar surface  212  between the proximate U-shaped longitudinal portion  12  and the shifted wall section  24 . The inner longitudinal planar face  66  is a mating surface for the first planar surface  212 . The first planar surface  212  can rest or slide on the inner longitudinal planar face  66 . The inner longitudinal edge  68  is a mating surface for the sloping wall  30  of the second longitudinal rib  28 . The sloping wall  30  can rest or slide on the inner longitudinal edge  68  to maintain the vertical side strip  5  into the cavity  58  of the vertical guide  3 . When present, the layer  40  of slippery, wear-resistant plastic material embedded into the surface of the second longitudinal rib  28  and of the sloping wall  30  facilitates sliding of the planar surface  212  onto the inner longitudinal planar face  66  and sliding of the sloping wall  30  on the inner longitudinal edge  68 . 
     In the same manner, the vertical side strip  5  defines a second planar surface  215  opposite the first planar surface  212  between the proximate U-shaped longitudinal portion  12  and the generally trapezoidal first longitudinal rib  22 . The second planar surface  215  slides onto the longitudinal edge  74  while a sloping wall  217  of the generally trapezoidal first longitudinal rib  22  slides on the inner surface of the angular longitudinal wall  72  to maintain the vertical side strip  5  into the cavity  58  of the vertical guide  3 . The layer  42  of slippery, wear-resistant plastic material embedded into the surface of the generally trapezoidal first longitudinal rib  22  facilitates sliding of the planar surface  215  onto the longitudinal edge  74  and sliding of the sloping wall  217  of the generally trapezoidal first longitudinal rib  22  onto the inner surface of the angular wall  72 . 
     In normal operation, the vertical guide  3  has a cross-section shaped substantially as shown on  FIGS. 6 and 7 . As the curtain  2  of the roll-up door system  1  is raised or lowered, the vertical side strip  5  slides into the vertical guide  3  with the link  19  of the vertical side strip  5  between the proximate U-shaped longitudinal portion  12  and the first longitudinal rib  22  sliding in the longitudinal slot  76 . More specifically, the first planar surface  212  slides on the inner longitudinal planar face  66  with the sloping wall  30  of the shifted wall section  24  sliding on the inner longitudinal edge  68  to retain the vertical side strip  5  into the cavity  58  of the vertical guide  3 . Also, the second planar surface  215  opposite the first planar surface  212  slides onto the longitudinal edge  74  while the sloping wall  217  of the generally trapezoidal first longitudinal rib  22  mates with an inner surface  218  of the angular longitudinal wall  72 , sliding or resting thereon to maintain the vertical side strip  5  into the cavity  58  of the vertical guide  3 . 
     However, when a wind load or impact causing a load exceeding a predetermined threshold is applied upon the curtain  2 , this load being transmitted to the vertical side strip  5 , such wind load or impact will cause deformation of the vertical guide  3 , in which the wall portions  54  and  56  separate from each other at the front of the vertical guide  3  to thereby spread apart the longitudinal edge  74  and the inner longitudinal planar face  66 , thereby widening the longitudinal slot  76 . Because the cross-section  55  of the wall portion  54  is thinner than the cross-section  57  of the wall portion  56 , the wall portion  54  tends to undergo a greater deformation than the wall portion  56  when a force is applied to the vertical guide  3 . Widening of the longitudinal slot  76  in turn allows the generally trapezoidal first longitudinal rib  22 , at first, and then the shifted wall section  24 , to pass through the longitudinal slot  76  and release the vertical side strip  5  from the vertical guide  3  with little, if any, damage to the curtain  2  or the vertical guide  3 . Notably, the obtuse angle  70  allows the sloping wall  217  to slide on the angular longitudinal wall  72  with relative ease. Of course, resilient material, for example aluminum, will enable such deformation of the vertical guides  3 . The deformation may be substantially elastic so that the vertical guide  3  returns to its original shape after deformation. The predetermined threshold for allowing release of the vertical side strip  5  under excessive wind load or under impact may be determined by those of ordinary skill in the art by proper selection of material for making the vertical guide  3  as well as by proper selection of the geometry, thickness, and size configurations of the various elements of the vertical guide  3 . In particular, thicknesses of the cross-sections  55  and  57  may be selected according to a desired predetermined threshold. 
     As an economical variant, the vertical guide  3  may be manufactured using a material that may be plastically deformable. While such vertical guide  3  may need to be repaired or replaced as a result of an event in which the vertical side strip  5  has been pulled out of the vertical guide  3 , overall damages should still be limited as the curtain  2 , and the doorway frame  4  may remain essentially unaffected. 
       FIG. 8  shows an interaction of the vertical side strip of  FIG. 3  with a first variant of the vertical guide. A vertical guide  100  is adapted to operate with the vertical side strip  5  as described hereinabove. The vertical guide  100  comprises a first vertical guide portion  154  and a second vertical guide portion  156  having respective series of threaded holes  152  and  153  for attachment to a doorway frame  4  using bolts such as  102 . In a particular embodiment, the first vertical guide portion  154  has a thinner cross-section  155  when compared to a cross-section  157  of the second vertical guide portion  156 . 
     The first vertical guide portion  154  is biased against a series of cylindrical, inner projections  180  of the second vertical guide portion  156  by a biasing element, for example a series of springs  185 . Each cylindrical projection  180  is threaded on its internal surface. The first vertical guide portion  154  comprises a non-threaded hole  181  in alignment with the cylindrical projection  180 . Each spring  185  is mounted onto a bolt  182  between an outer surface  183  of the first vertical guide portion  154  and a head  184  of the bolt  182 . The bolt  182  is threaded into the internally threaded cylindrical projection  180  through the hole  181 . 
     In normal operation, the springs  185  maintains the first vertical guide portion  154  in a rest position against the projection  180  of the second vertical guide portion  156 , as shown on  FIG. 8 . While in the rest position, the first vertical guide portion  154  forms, with the second vertical guide portion  156 , a longitudinal slot  176  for receiving the link  19  of the vertical side strip  5  between the proximate U-shaped longitudinal portion  12  and the first longitudinal rib  22 . It can thus be appreciated that, in normal operation, the vertical guide  100  operates in an equivalent manner to the vertical guide  3  of earlier Figures. 
     Under excessive wind load or impact conditions, the vertical guide  100  is deformed by moving the first vertical guide portion  154  away from the second vertical guide portion  156 , compressing the springs  185 , thereby widening the longitudinal slot  176  to allow the generally trapezoidal first longitudinal rib  22  first, and then the shifted wall section  24 , to pass through the longitudinal slot  176  and releasing the vertical side strip  5  from the vertical guide  100 . In the embodiment of  FIG. 8 , the predetermined threshold for releasing the vertical side strip  5  under excessive wind load or under impact may be adjusted by proper selection of material for making the vertical guide  100 , by proper selection of the geometry, thickness and size configurations of the various elements of the vertical guide  100 , and by a number and a level of resilience of the springs  185 . 
       FIG. 9 a    is a top cross-sectional view of a second variant of the vertical guide.  FIG. 9 b    is a top cross-sectional view of one portion of the vertical guide of  FIG. 9 a   .  FIG. 9 c    is a top cross-sectional view of another portion of the vertical guide of  FIG. 9 a   . Referring at once to  FIGS. 9 a , 9 b  and 9 c   , a vertical guide  200  is adapted to operate with the vertical side strip  5  as described hereinabove. The vertical guide  200  comprises a first vertical guide portion  254  and a second vertical guide portion  256 , respectively having series of threaded holes for attachment to a doorway frame  4  using bolts. These threaded holes are not shown in the cross-sectional view of  FIGS. 9 a , 9 b  and 9 c   , but are located along a height of the vertical guide  200 , in the same or similar manner as threaded holes  142 ,  153  and bolts  102  of  FIG. 8 . The first and second vertical guide portions  254  and  256  can be separably mounted on the doorway frame  4 . 
     Holes  202  and  204  are provided on the first and second vertical guide portions  254  and  256 , respectively, allowing assembly of these two portions using bolts and nuts (not shown), or similar attachments. A function and operation of the vertical guide  200  is similar to that of the vertical guide  3  of  FIG. 6 . However, a longitudinal slot  276  defined between the first and second vertical guide portions  254  and  256  can be made to vary in width upon installation of the vertical guide  200  on the doorway frame  4 . For example, the longitudinal slot  276  can be made tighter at the bottom of the doorway frame  4 , becoming slightly wider towards the top of the doorway frame  4 , in order to accommodate for generally higher load pressure present at the bottom of a roll-up door. 
     On  FIGS. 9 b  and 9 c   , all dimensions are in inches, except for angles which are in degrees, and are provided as a non-limiting example embodiment. 
     Though embodiments of the door, deformable guide and guiding system have been presented hereinabove in the context of roll-up doors, it should be understood that the present disclosure equally applies in the context of rollable doors operating in a vertical plane but mounted on horizontal guides. As a result, the present disclosure includes components of a rollable door having a vertical curtain that may be rolled sideways between an upper horizontal guide and a lower horizontal guide. The present disclosure further applies to rollable doors operating in a horizontal plane, having a horizontal curtain rollable between two horizontal guides generally positioned at a same height. Such doors may for example act as opening and closing covers for food and grain storage and for fertilizer hoppers. 
     Those of ordinary skill in the art will realize that the description of the door, deformable guide and guiding system for rollable doors are illustrative only and are not intended to be in any way limiting. Other embodiments will readily suggest themselves to such persons with ordinary skill in the art having the benefit of the present disclosure. Furthermore, the disclosed door, deformable guide and guiding system may be customized to offer valuable solutions to existing needs and problems of limiting damages to buildings under excessive load situations. 
     In the interest of clarity, not all of the routine features of the implementations of the door, deformable guide and guiding system are shown and described. It will, of course, be appreciated that in the development of any such actual implementation of the door, deformable guide and guiding system, numerous implementation-specific decisions may need to be made in order to achieve the developer&#39;s specific goals, such as compliance with application-, system-, and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the field of door systems having the benefit of the present disclosure. 
     Although the present disclosure has been described hereinabove by way of non-restrictive, illustrative embodiments thereof, these embodiments may be modified at will within the scope of the appended claims without departing from the spirit and nature of the present disclosure.