Abstract:
An overhead door assembly in which the door assembly has a vertical closed position and a horizontal opened position, the door assembly including a frame having a horizontal support member and first and second vertical members fixedly mounted to either end of the horizontal member, the vertical members are fixedly mounted to the ground. A one piece door member includes top and bottom horizontal ends and first and second vertical sides and is pivotally mounted to the horizontal member of the frame with the door member being movable from a closed position to an opened position about a pivot point. A hydraulic cylinder is pivotally mounted on a portion of either of the first or second vertical members and the second end of the hydraulic cylinder is pivotally mounted to the door member. The hydraulic cylinder includes a ram movably disposed within the cylinder and transmits an opening and closing force to the door member.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S)  
       [0001]    This application claims the benefits of U.S. Provisional Application No. 60/107,826 filed Nov. 10, 1998. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to overhead doors for use in buildings, especially for buildings with large openings.  
           [0003]    Agricultural, aviation, commercial buildings and the like generally require a large opening for accommodating trucks, tractors, airplanes, large farm equipment (e.g. combines), large industrial equipment, and others, through such opening. Common types of conventional door assemblies currently used to accommodate this need include two piece center hinging cable drawn doors (bi-fold) and horizontally sliding doors that are supported by and slide on a track system. These types of conventional doors generally require a larger opening than is required to accommodate the door members, thus reducing the overall available vertical height of the building opening that can be provided for a given limited area of space or land. Furthermore, these types of doors require that the building be engineered with extra reinforcement because the load of the door is generally supported by the building itself.  
           [0004]    The most common types of door assemblies used in buildings are the two piece center hinging cable drawn doors. Cables draw the bottom end of the door directly vertically towards the top of the door, while being guided on a track system. During the opening process, the hinged portion of the door moves in an outwardly and upwardly direction causing the bottom leaf of the door to fold underneath the top leaf. Consequently, this requires a larger building height to accommodate the desired opening. Furthermore, since the door itself is mounted to the building structure, the building bears the entire load of the door and must be reinforced accordingly. The bi-fold door also has other disadvantages because it is operated by a cable/pulley system having many moving parts, resulting in a high wear and high maintenance system. Furthermore, the bi-fold door must be locked down manually to effect a complete closure and has an inherently slow open/close cycle time, making the opening/closing process inconvenient and time consuming. Additionally, in the event of a failure of any of these mechanical components, the door may drop, thus creating a safety hazard. Moreover, the bi-fold door is drafty because it closes against the exterior of the building and the joints are exposed to the elements.  
           [0005]    Other conventional types of door assemblies include horizontally sliding doors. These types of doors are supported by and slide on a track system. Problems also arise with these doors since the track can accumulate ice, mud and other debris that can push the door out of alignment with the track, making it difficult to operate. Once the doors are out of alignment, they are generally difficult to open and close. Moreover, horizontally sliding doors require storage space on either side of the building opening to accommodate the door leaves when the door is in the open position. The storage space required to accommodate the door leaves reduces the usable width of the building opening that can be provided for a given limited area of space or land.  
           [0006]    Accordingly, for the foregoing reasons, there is a need for a door that pivots on a load bearing frame that is separate from the building structure such that the door does not hang on and load the building structure. There is also a need for a door that includes its own separate framework, such that loads placed on means for operating the door are transferred to the load bearing frame and not to the building structure.  
           [0007]    There is also a need for a door that maximizes the useable space of the available opening in the building. For example, there is a need for a door that utilizes virtually no overhead or side door storage space making it possible to provide a smaller building size for a given required building opening size, or maximize an existing opening available in a building.  
           [0008]    Furthermore, there is a need for a door member that has no moving parts such as pulleys, shafts, bearings, gear boxes, track systems or the like, thus making the door member virtually maintenance free. Also, there is a need for a door that includes means for connecting alternative power sources for operating the door in the event of an electrical power outage. There is also a need for a door that closes flush with the exterior building wall to provide a weather tight seal.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    To overcome the limitations of the related art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the invention is directed to an apparatus for an outwardly opening hydraulically actuated door assembly for a building having an opening to be closed by the door assembly.  
           [0010]    The apparatus having features of the invention is a door assembly that hangs on its own framework that is separate from the building structure. The door assembly having features of the invention can be custom built to fit virtually any building, new or existing. The building structure does not have to be taller than the door to accommodate the door. The door assembly having features of the invention can be horizontal support member and first and second vertical members fixedly mounted to either end of the horizontal member, the vertical members being fixedly mounted to the ground. The assembly also includes a one-piece door member having a thickness including top and bottom horizontal ends and first and second vertical sides, the top horizontal end of the door member being pivotally mounted to the horizontal member of the frame, the door member being movable from a closed position to an open position about the pivot point. The assembly also includes a hydraulic cylinder having a first and second end, the first end pivotally mounted on a portion of either one of the first and second vertical member, and the second end pivotally mounted to the door member.  
           [0011]    A further aspect of the invention includes a frame for an overhead door. The frame includes a horizontal support member; first and second vertical members fixedly mounted to either end of the horizontal member; and ground anchoring means disposed on the first and second vertical members, anchoring the frame to the ground.  
           [0012]    Still another aspect of the invention includes an overhead door having a vertical closed position and a horizontal open position provided in a building having an opening to be closed by the door. The overhead door provided in the building includes a one-piece door member having a thickness including top and bottom horizontal ends and first and second vertical sides. The overhead door provided in the building also includes means for fixedly mounting the top horizontal end of the door member to a support structure; means for mounting to the door member a mechanism adapted and configured to open and close the door member; means for supporting the bottom horizontal end of the door member; and means for sealing the bottom horizontal end of the door member against the ground.  
           [0013]    Yet another aspect of the invention includes a frame for an overhead door provided in a building having an opening to be closed the door. The frame provided in the building includes a horizontal support member; first and second vertical members fixedly mounted to either end of the horizontal member; and ground anchoring means disposed on the first and second vertical members, anchoring the frame to the ground.  
           [0014]    These and various other features of novelty as well as advantages which characterize the invention are pointed out with particularity in the claims annexed hereto and form a part hereof. However, for a better understanding of the invention reference should be made to the drawings which form a further part hereof, and to accompanying descriptive matter, in which there are illustrated and described specific examples of an apparatus in accordance with the invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    Referring now to the drawings in which like reference numbers represent corresponding parts throughout, where:  
         [0016]    [0016]FIG. 1 is a view of a door assembly provided in a building;  
         [0017]    [0017]FIG. 2 is a detail view of a door assembly provided in a building;  
         [0018]    [0018]FIG. 3 is a front elevation view of a door assembly;  
         [0019]    [0019]FIG. 4 is a front isometric view of a door assembly with the door in a partially open position;  
         [0020]    [0020]FIG. 5 is a view of upper and lower pinpoints of a hydraulic cylinder;  
         [0021]    [0021]FIG. 6 is a view of upper and lower pinpoints of a hydraulic cylinder in a closed position;  
         [0022]    [0022]FIG. 7 is a side view elevation of a door assembly;  
         [0023]    [0023]FIG. 8 us a top cut away view of a jamb connection to the floor;  
         [0024]    [0024]FIG. 9A is a side cut away view of a bottom seal;  
         [0025]    [0025]FIG. 9B is a top cut away view of a side seal;  
         [0026]    [0026]FIG. 10A- 10 C are views of the top seal;  
         [0027]    [0027]FIG. 11 is a view of a door splice;  
         [0028]    [0028]FIG. 12 is a front elevation view of a door assembly;  
         [0029]    [0029]FIG. 13 is a front isometric view of a door assembly with the door in a partially open position; and  
         [0030]    [0030]FIG. 14 is a block diagram of a hydraulic power system. 
     
    
     DETAILED DESCRIPTION  
       [0031]    In the following description of the specific embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration the specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized as structural changes may be made without departing from the scope of the present invention.  
         [0032]    [0032]FIGS. 1 and 2 illustrate generally a building  10  provided with a door assembly  12  in a partially open position. The door assembly includes a frame  14 . The frame comprises two vertical support members  14 A, B (e.g. steel tube jambs) and a horizontal support member  14 C (e.g. a steel tube header). The assembly also includes a door member  22  (supporting grid structure only is shown). The door member  22  includes a support truss  16  and a weather tight resilient seal  18  disposed along the bottom horizontal end of the door member  22 . The door assembly  12  also includes a hydraulic cylinder  20  for opening and closing the door member  22 .  
       Door Frame  
       [0033]    [0033]FIG. 3 illustrates the door assembly  12  including the support frame  14 , the supporting grid structure of the door member  22 , the truss support system  16 , the door member seal  18  and the hinges  34 ,  38  providing the pivot point for opening and closing the door member  22 .  
         [0034]    The door assembly  12  mounts to a given building structure via the provided supporting frame  14  from which the actual door member  22  is hung. The frame  14  includes the horizontal steel tube header  14 C, and the vertical steel tube jambs  14 A, B that connect to the floor or the ground. Both vertical jambs  14 A, B are secured to the given building structure  10  using fastening means (not shown) that are generally known by those skilled in the art such as screws, rivets, adhesives, and the like. Steel plates  24 A, B are secured to the bottom of each vertical jamb  14 A, B connecting to the floor. The steel plates  24 A, B are anchored to a concrete pad or footing or to other means provided.  
         [0035]    The door member  22  includes load bearing supporting uprights  26  and Z-girt members  32  for attaching tin or other “skinning” materials for covering the door member&#39;s  22  supporting frame structure. Generally, the door member  22  is covered or “skinned” with the same material as the rest of the building. The door member  22  also includes an upper structural member  28  and a lower structural member  30 . Together the supporting members  26 ,  28 ,  30 ,  32  provide the basic framework of the door member  22 .  
         [0036]    The door assembly  12  includes outer hinges  38  and inner hinges  34  for mounting and supporting the door member  22  on the frame  14 . The hinges  34 ,  38  also provide a pivoting point for the door member  22  while opening or closing the building opening. The door assembly  12  also includes a hinged angled member  36  (e.g. an angle iron) and side angled members  40  (e.g. angle irons). The angled members  36 ,  40  have a compressed foam seal disposed thereon. The foam provides a weather tight seal on three sides of the door member. The door member  22  also includes a door splice member  31  for splicing the upper vertical support members  26  with the lower vertical support members  27 .  
         [0037]    [0037]FIG. 4 illustrates the door member  22 , the truss support system  16 , the door member sealing means  18  and the hinging means  34 ,  38  in accordance with one embodiment of the present invention, as follows:  
       Door Member  
       [0038]    The door member  22  is constructed of steel tubing and includes four basic components. The lower pinpoint assembly  42  and the outer hinge  38 B are attached to the load bearing upright  26 E which is located vertically at the outermost portion of the door member  22 . The center hinge  34 C is attached to the center support upright  26 D which, is located in a vertical position between the load bearing upright tubes  26 A, B at a spacing not exceeding eight feet. The upper structural tube  28  is placed and secured horizontally across the top of all the uprights  26 . The lower structural tube  30  is placed and secured horizontally across the bottom of all the uprights  26  or  27 , depending on the configuration of the door member  22 .  
       Truss Support System  
       [0039]    The door member  22  is constructed with a load bearing arc such that the door member  22  does not lose its structural integrity whenever it is placed in an outwardly, horizontal open position. Pressure is applied on the lower structural tube  30  creating the arc. A “V-truss”  16  is disposed horizontally along the bottom horizontal end of the door member  22  and is fastened onto the lower outside face of the door member  22  with the point of the “V” facing directly outwardly, thus maintaining the load bearing arc.  
       Door Member Seal  
       [0040]    The seal  18  is disposed horizontally along the bottom portion of the door member  22 . The seal  18  is a rubber strap secured to the inside and the outside face of the lower structural tube  30 . The seal  18  wraps underneath the door member  22  when the door member  22  is in a closed position, thus creating a weather tight seal capable of conforming to irregularities of the floor surface.  
         [0041]    The top seal and side seals are constructed of angled members  36 ,  40  and a compressed foam stripping. The vertical angled member  40 B is secured vertically to the door member  22  and closes flush with the outside face of the load bearing uprights  26 A, B. The horizontal angled member  36  is secured horizontally to the door member  22  and closes flush with the outside face of the upper structural tube  28 . When the door member  22  is in a close position the angled member  40 B overlaps the inside comer of the outside face of the jamb  14 B. Likewise, the angled member  36  overlaps the outside face of the horizontal header  14 C. The compressed foam stripping is disposed along the entire length of the inside portion of the angled members  36 ,  40  and overlaps the outside face of the door frame  14 . Insulation up to five-inches thick may be added to the interior portion of the door member  22 , thus providing an insulating R-value between  19 - 24 .  
       The Hinges  
       [0042]    The outer hinges  38  and the inner hinges  34  are secured above each vertical support upright  26 . A first portion of the hinges  31 ,  35  includes a steel plate with an end wrapped around to form an elongated hole therethrough. The steel plate is fastened to the horizontal angled member  36 . A second portion of the hinges  33 ,  37 , includes a steel plate with an end wrapped around to form an elongated hole therethrough, matching the size and placement of the first portion such that the first portion  31 ,  35  is accommodated within the second portion  33 ,  37 . The second hinge portions  33 ,  37  are also fastened to the top horizontal header  14 C. The door member  22  is fastened to the frame  14 C when the holes in both the first and second portions  31 ,  35  and  33 ,  37 , respectively, are aligned and a bolt is placed through the elongated holes formed by the first and second portions  31 ,  35  and  33 ,  37 , respectively.  
       Cylinder Pivot  
       [0043]    [0043]FIG. 5 illustrates the cylinder  20  pivotal means  42 ,  44  of the hydraulic power system in accordance with one embodiment of the present invention. An upper pinpoint assembly  44  constructed of one-inch thick steel plate includes two components, a J-shaped bracket  48  and a flat steel strap  46 . The J-shaped bracket  48  is constructed of steel tubing and one-inch thick steel plate having a hole drilled therethrough. A top portion of the cylinder  52  is placed and pinned with a chrome shaft pin  50 A to the J-shaped bracket  48 . The J-shaped bracket  48  is perpendicularly placed and secured to the inside face of the jamb  14 B facing directly inwardly in such a manner as to position the steel plate portion on the same plane as the steel plate  56  of the lower pinpoint assembly  42 . The flat steel strap  46  is bent in such a manner as to be secured to the most inward portion of the J-shaped bracket  48  and the inside face of the jamb  14 B, giving the upper pinpoint assembly  44  a three-point secured attachment.  
         [0044]    The lower pinpoint assembly  42  is also constructed of a one-inch thick steel plate  56  and includes a teardrop shaped one-inch thick steel plate  54  with a hole drilled therethrough, in which the levis end of the cylinder is secured with a chrome shaft pin  50 B to the flat steel bar  56 . The lower pinpoint assembly  42  is mounted and secured to the load bearing upright  26 E of the door member  22  in such a manner as to allow the door to be closed tightly and securely against the door frame  14  as the cylinder ram  60  is retracted inwardly  51 .  
       Hydraulic Powering System  
       [0045]    [0045]FIG. 6 illustrates a cross sectional view of the door member  22  in a closed position. The hydraulic cylinder  20  is shown with the ram  60  in a fully retracted position.  
         [0046]    [0046]FIG. 7 is a side elevational view of the door member  22  in a partially open position. The steel plate  24 B is secured to the bottom of the vertical jamb  14 B for anchoring or connecting the jamb  14 B to the floor, concrete pad or footing. The center splice  39  (shown in detail at FIG. 11) is used to splice the top vertical support members  26  to the bottom vertical support members  27 .  
         [0047]    [0047]FIG. 8 is top cut away view of the jamb  14 A ( 14 B) connection to the floor or concrete pad  64 . The jamb  14 A ( 14 B) is secured or anchored to a concrete footing  64  with cement anchor bolts (not shown) disposed through hole  66  formed in the steel plate  24 . The anchor bolt secures the steel plate  24  and the jambs  14 A,  14 B to provide a secure fastening of the frame  14  such that it is capable of supporting the load of the door member  22 .  
         [0048]    [0048]FIG. 9A is a side cut away view of the bottom seal  18 . The seal  18  is made of a resilient weather resistant material, and is fastened to the lower structural member  30  with sheet metal screws  72 . Those skilled in art will appreciate that any number of fastening means may be utilized to fasten the seal  18  to the lower structural member without departing from the scope of the present invention. The seal  18  makes a weather tight seal between the door member  22  and the ground  70 .  
         [0049]    [0049]FIG. 9B is a top cut away view of the side seal  68  sealing the two vertical sides on the top horizontal portion of the door member  22 . The side seal  68  is formed of a compressed foam and is attached to the angled member  40 B such that the foam  68  seals against the jamb  14 B when the door member  22  is in a closed position. The foam seal  68  is fastened to the underside of the angled members  40 A and  36  such that a seal is formed against the two vertical jambs  14  and the horizontal header  14 C when the door member  22  is in a closed position. The angled members  40 A, B are fastened to load bearing upright members  26 A, E, respectively. Angled member  36  is fastened to the hinges  34 ,  38 , such that the door member  22  is supported by the hinges  34 ,  38 .  
         [0050]    FIGS.  10 A-C illustrate several views of the top horizontal header  14 C fastened to the hinges  34 ,  38 . Hinge portions  33  or  37  (depending on the specific configuration) are fastened to the top horizontal header  14 C. Hinge portions  31  or  35  (depending on the specific configuration) are fastened to the top horizontally disposed angled member  36 . The angled member  36  is fastened to the upper structural member  28 . The upper structural member  28  is fastened to the vertical uprights  26 . Hinge portions  33 ,  37  and  31 ,  35  are fastened by a bolt  41  inserted through axially defined holes of the hinge portions of  33 ,  37  and  31 ,  35 .  
         [0051]    [0051]FIG. 11 is a detailed view of the door splice. Lower vertical member  27  is spliced to the upper vertical member  26  with splice connection channels  39 . The splice connection channels  39  are welded at  78  to the upper vertical members  26 . The lower vertical members  27  are fastened to each splice connection channels  39  with bolts  74  and nuts  76 .  
         [0052]    [0052]FIG. 12 illustrates an alternative embodiment of a door assembly  112  including the support frame  14 , the supporting grid structure of the door member  122 , the truss support system  16 , the door member seal  18  and the hinges  134 ,  138  providing the pivot point for opening and closing the door member  122 .  
         [0053]    The door assembly  112  mounts to a given building structure via the provided supporting frame  14 , from which the door member  122  is hung. The frame  14  consists of the horizontal steel tube header  14 C, and the vertical steel tube jambs  14 A, B that connect to the floor, the ground, a concrete pad or the like. Both vertical jambs  14 A, B are secured to the given building structure  10  using fastening means (not shown) generally known by those skilled in the art such as screws, rivets, adhesives, and the like. Steel plates  24 A, B are secured to the bottom of each vertical jamb  14 A, B for anchoring the vertical jambs  14 A, B to the floor, concrete pad or footing.  
         [0054]    The door member  122  includes load bearing vertical supporting uprights  126  and Z-girt members  32  for attaching tin or other “skinning” materials for covering the door member&#39;s  122  supporting frame structure. The door member  122  also includes an upper structural member  28  and a lower structural member  30 . Together the supporting members  26 ,  28 ,  30 ,  32  provide the basic framework for the door member  122 .  
         [0055]    The door assembly  112  includes outer hinges  138  and inner hinges  134  for supporting the door member on the frame  14 . The hinges  134 ,  134  also provide means for the door member  122  to pivot while opening or closing the building opening. The door assembly  112  also includes a hinging horizontal angled member  36  having a compressed foam stripping seal fastened to an underside thereto and side vertical angled members  40  also having a compressed foam stripping seal fastened to an underside thereto.  
         [0056]    [0056]FIG. 13 illustrates an alternative embodiment of the door member  122 , the truss support system  16 , the door member sealing means  18  and the hinges  134 ,  138  in accordance with one embodiment of the present invention, as follows:  
       Door Member  
       [0057]    The door member  122  is constructed of steel tubing and includes four basic components. The load bearing vertical member  126 E is located vertically at the outermost portion of the door  122 . The pinpoint assembly  42  and the outer hinge  138 B are fastened to the vertical member  126 E. The center support vertical member  126 D is located in a vertical position between the load bearing upright tubes  126 A, B at a spacing not exceeding eight feet. The center hinge  134 C is fastened to the vertical member  126 D. The upper structural tube  28  is placed and secured horizontally across a top end of all the vertical members  126 . The lower structural tube  30  is placed and secured horizontally across a bottom end of all the vertical members  126 .  
       Truss Support System  
       [0058]    The door member  122  is constructed with a load bearing arc such that the door member  122  does not lose its structural integrity whenever it is placed in an outwardly, horizontal, open position. Pressure is applied to the lower structural tube  30  creating an arc, then a “V-truss”  16  is disposed horizontally along the structural tube  30  and is fastened onto the lower outside face of the door member  122  with the point of the “V” facing directly outward, thus maintaining the load bearing arc.  
       Door Member Seal  
       [0059]    The seal  18  is disposed horizontally along the bottom portion of the door member  122 . The seal  18  is a rubber strap secured to the inside and the outside face of the lower structural tube  30 . The seal  18  wraps underneath the door member  122  when the door member  122  is in a closed position, thus creating a weather tight seal capable of conforming to irregularities of the floor surface.  
         [0060]    The top seal and side seals are constructed of angled members  36 ,  40  and a compressed foam stripping  68 . The vertical angled member  40 B is secured vertically and flush to the outside face of the load bearing uprights  126 A, B and is secured horizontally and flush to the outside face of the upper horizontally disposed structural tube  28 . When the door member  122  is in a closed position the angled member  40 B overlaps the inside corner of the outside face of the jamb  14 B. Likewise, the angled member  36  overlaps the outside face of the horizontal header  14 C. Compressed foam stripping  68  is disposed along the entire length of the inside portion of both the top horizontal angled member  36  and the side vertical angled members  40  that overlap the outside of the door frame  14 .  
       The Hinges  
       [0061]    Both the outer hinge  138  and the inner hinge  134  are constructed of an outer hinge component  133  and an inner hinge component  131 , one difference being the thickness of the steel from which they are constructed. The outer hinge component  133  includes two steel plates, with a drilled hole in each, placed vertically and parallel to each other, spaced apart at a predetermined distance and secured to the horizontal header  14 C of the frame  14 . The set of outer hinge components  133  are secured above each load bearing vertical member  126 A, E and above each center support vertical member  126 B, C, D.  
         [0062]    The inner hinge component  131  includes an elongated piece of steel with a hole drilled therethrough, matching the size and placement of the hole defined in the outer hinge component  133 . The inner hinge components  131  are placed and secured to the top of the door member  122  in a manner such that they are mounted vertically and parallel to the outer hinge component  133  when the door member  122  is in a closed position. The door member  122  is fastened to the frame  14  when the holes in both the outer hinge components  133  and the inner hinge components  131  are aligned and a bolt is placed and secured through holes defined by both hinge components  131 ,  133 .  
         [0063]    [0063]FIG. 14 is a block diagram of a hydraulic system  98  according to one embodiment of the present invention. The hydraulic system  98  comprises the hydraulic cylinder  20 , a ram  60 , mechanical safety stops  80 , hydraulic hoses  84 , a three way valve  86 , a holding tank  88  and a pump  90 . The hydraulic cylinder  20  includes the ram  60  (or piston) and mechanical safety stops  80  to mechanically restrict the travel of the ram  60 . In case hydraulic power is lost whenever the ram  60  is supporting the load of the door member  22 , a restriction orifice  82  releases the hydraulic fluid at a controlled rate such that the door member  22  is lowered easily to the ground. The three way valve  86  controls the direction for the door member  122  (e.g. open or close). The hydraulic fluid collects in the holding tank  88  which is fluidly coupled to the pump  90 . The pump is electrically operated by electrical power source  92 . In case the electrical power source  92  fails, is disrupted or is unavailable (e.g. remote locations) the hydraulic system provides couplers to connect an alternate fluid power source  94  (e.g. the hydraulic system of a tractor) to operate the door member  22 .  
         [0064]    In use, the three-way valve  86  directs fluid to the cylinder  20  and actuates the ram  60 . If fluid is introduced at the rear of the cylinder  20  the ram  60  is driven in an outwardly direction  53  thus raising the door member  22  ( 122 ). Through operation of the three-way valve  86  fluid may be introduced at the forward end of the cylinder moving the ram  60  in an inwardly direction  51 , thus lowering the door member  22  ( 122 ). The ram may be stopped at any intermediate position between the mechanical stops  80  to maintain the door member  22  ( 122 ) in a partially open position.  
         [0065]    Two hydraulic cylinders  20  (only one is shown) are used, one on either side of the door member  22  ( 122 ) connecting the upper pinpoint assembly  44  to the lower pinpoint assembly  42 , to operate the door member  22  ( 122 ) such that it moves from a vertically closed position to a horizontal open position by extending the ram  60  in an outwardly direction  53 . The door member  22  is closed by inwardly  51  retracting the cylinder ram  60 .  
         [0066]    The foregoing description of the specific embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not with this description, but rather by the claims appended hereto.  
         [0067]    Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.