Abstract:
Methods of securing a support beam to a structure such as a cargo roller tray or a passenger cabin is achieved using a shear fitting. The shear fitting has a back plate which fastens to the support beam. The shear fitting additionally has parallel lugs which extend from the back plate and fasten to the structure. Web extenders which extend from the shear fitting perpendicular to the lugs may additionally be used to further fasten the support beam to the structure.

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This patent application is a divisional application of co-pending, commonly owned U.S. patent application Ser. No. 11/759,415, filed Jun. 7, 2007, entitled “Cargo Roller Tray Shear Fitting,” which is hereby incorporated in its entirety by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    Embodiments of the disclosure relate to shear fittings in general and shear fittings used to fasten structures to support beams of aircrafts. 
       BACKGROUND 
       [0003]    Cargo roller trays are used in vehicles (e.g., air craft, ships, trucks, etc.) and storage locations (e.g., holds, containers, and warehouses, etc.) to speed the movement of cargo. Typically, the cargo roller trays are joined to structural supports (e.g., floor beam, floor joists, etc) or a floor using fasteners. 
         [0004]    The cargo roller trays in the past have been attached to structural supports by positioning the cargo roller tray on the support, drilling holes through both the cargo roller tray and the support, and then inserting fasteners though the holes. This fastening process required the installer to drill holes and to clean up the drill shavings after the holes were drilled. This process also required the use of backing plates for the fasteners, since the tension in the fastener held the cargo roller tray in position. 
         [0005]    In an effort to speed the assembly process, both the support and the cargo roller tray are predrilled. However, when the holes in the cargo roller tray and the support did not line up, re-work was required 
         [0006]    Accordingly, there is a need for a shear fitting that can fasten a structure such as a cargo roller tray to the support such that re-work is minimized when using predrilled components. 
       SUMMARY 
       [0007]    Embodiments of the disclosure may advantageously address the problems identified above by providing, in one embodiment, a shear fitting for joining a structure such as a cargo roller tray and/or at least a portion of a passenger cabin to a support beam. The shear fitting includes a base plate and parallel lugs extending from the base plate. 
         [0008]    The shear fitting may include a base plate having a slot to fasten the shear fitting to the support beam. The shear fitting may additionally include parallel lugs having lug apertures to fasten the shear fitting to the structure. The slot may permit the shear fitting to shift (traverse) a predetermined distance along a length of the support beam. 
         [0009]    In some situations, the shear fitting may be used in aircrafts to join structures such as an aircraft cargo roller tray and/or at least a portion of a passenger cabin to a support beam. 
         [0010]    The features, functions, and advantages that have been discussed can be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The accompanying drawings incorporated in and forming part of the specification illustrate several embodiments of the disclosure. In the drawings: 
           [0012]      FIG. 1  illustrates a method of joining a cargo roller tray to a support as provided in the related art. 
           [0013]      FIGS. 2A and 2B  illustrate a shear fitting with a single lug. 
           [0014]      FIG. 3  illustrates a first embodiment of a shear fitting with two lugs. 
           [0015]      FIG. 4  illustrates a second embodiment of a shear fitting with two lugs. 
           [0016]      FIGS. 5 and 6  illustrate the second embodiment of the shear fitting with two lugs joining a cargo roller tray to a support. 
           [0017]      FIG. 7  illustrates an exemplary aircraft that may contain one of the embodiments illustrated above. 
           [0018]      FIG. 8  illustrates a cross-section of the aircraft illustrated in  FIG. 7 . 
       
    
    
       [0019]    Reference will now be made in detail to embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. 
       DETAILED DESCRIPTION 
       [0020]    The use of the disclosed shear fitting may speed joining a cargo roller tray to a support and may reduce the amount of re-work when assembling pre-drilled components. 
         [0021]      FIG. 1  shows an example from the related art of a cargo roller tray  12  joined to support  14  using fasteners  18  and backing plate  16 . Backing plate  16  is used to spread the load since the tension of fasteners  18  holds the cargo roller tray  12  in position. 
         [0022]      FIG. 2  illustrates one embodiment of a shear fitting that may be used to join a cargo roller tray to a support. Shear fitting  100  may have a back  110 . Typically, back  110  has at least two slots  140  through which shear fitting  100  may be fastened to the support. In some embodiments there may be one slot and in others there may be more than two slots. The number of slots depends on the size and loads on the fasteners. The slots  140  permit the position of the shear fitting  100  to shift. This shift may enable joining the cargo roller tray to the support without the rework associated with holes in the cargo roller tray that do not align with holes in the support. 
         [0023]    The shear fitting  100  may also have a lug  120  with a hole or aperture  130 . The lug projects from the back  110 . In some embodiments the angle between the lug  120  and back  110  may be approximately 90 degrees. In other embodiments the angle between the lug  120  and back  110  may be an acute or obtuse angle. 
         [0024]    The aperture  130  permits the shear fitting to be fastened to the cargo roller tray. In some embodiments, such as illustrated in  FIG. 2B , the aperture  130  may be oversized so that the aperture will be capable of receiving a fastener even if the corresponding hole in the cargo roller tray is at its worst case position, but still in tolerance. In other embodiments, aperture  130  may be a slot. In further embodiments the slot in the lug may be located at approximately 90 degrees to the slot(s)  140  in the back  110 . 
         [0025]      FIG. 3  illustrates a second embodiment of shear fitting  200 . In this embodiment the shear fitting  200  has a back  220  and two lugs  210 . Each lug may have an aperture  212 . The apertures are similar to the aperture  130  discussed above. 
         [0026]    Similar to the back  110  discussed above, back  220  may have one or more slots  222 . Slots  222  are similar to slots  140  discussed above. 
         [0027]      FIG. 4  illustrates a modification of the embodiment shown in  FIG. 3 . A similar modification may be made to the embodiment shown in  FIG. 2 . As illustrated in  FIGS. 5 and 6 , this modification may be advantageously used when a portion of a flange  20  on a support beam  14  is removed or the support beam is manufactured with a notch  26  for installation of the shear fitting  300 . 
         [0028]    In the embodiment shown in  FIG. 4  the shear fitting  300  includes a web  340  and web extensions  330 . The remaining portions of shear fitting  300  are similar to shear fitting  200  discussed above. The web extensions  330  may each include an aperture  332 . Aperture  332  is configured to permit the shear fitting  300  to be fastened to the flange on a support beam. 
         [0029]    The addition of web  340  and web extensions  330  help mitigate the loss of structural strength caused by the notch  26  in the flange  20  of the support beam  14  in which the shear fitting  300  is installed. 
         [0030]    The shear fittings disclosed herein may be formed from metal using current or future metal forming techniques, e.g., casting, machining, forging, etc. The shear fittings may also be formed from plastic, glass reinforced plastic, composites, etc. using current or future forming techniques, e.g., molding, machining, etc. The materials used may be selected based on the strength and weight requirements of a particular application. 
         [0031]    Referring now to  FIG. 7 , a side elevation view of an aircraft  700  having one or more of the disclosed embodiments is shown. With the exception of the embodiments according to the present disclosure, the aircraft  700  typically includes components and subsystems generally known in the pertinent art, and in the interest of brevity, will not be described further. The aircraft  700  generally includes one or more propulsion units  702  that are coupled to wing assemblies  704 , or alternately, to a fuselage  706  or even other portions of the aircraft  700 . Additionally, the aircraft  700  also includes a tail assembly  708  and a landing assembly  710  coupled to the fuselage  706 . In some embodiments the fuselage  706 , tail assembly  708  and nose assembly  712  may form an airframe  714 . In other embodiments the airframe may also include wings  704 . 
         [0032]    The aircraft  700  further includes other systems and subsystems generally required for the proper operation of the aircraft  700 . For example, the aircraft  700  includes a flight control system (not shown in  FIG. 7 ), as well as a plurality of other network, electrical, EC, mechanical and electromechanical systems that cooperatively perform a variety of tasks necessary for the operation of the aircraft  700 . Accordingly, the aircraft  700  is generally representative of a commercial passenger or cargo aircraft, which may include, for example, the 737, 747, 757, 767 and 777 commercial aircraft available from The Boeing Company of Chicago, Ill. Although the aircraft  700  shown in  FIG. 7  generally shows a commercial aircraft, it is understood that the various embodiments of the present disclosure may also be incorporated into flight vehicles of other types. Examples of such flight vehicles may include manned or even unmanned military aircraft, rotary wing aircraft, ballistic flight vehicles or orbital vehicles, as illustrated more fully in various descriptive volumes, such as Jane&#39;s All The World&#39;s Aircraft, available from Jane&#39;s Information Group, Ltd. of Coulsdon, Surrey, UK. Additionally, those skilled in the art will readily recognize that the various embodiments of the present disclosure may also be incorporated into terrestrial or even marine vehicles. 
         [0033]    As shown in the exemplary aircraft cross section in  FIG. 8 , the aircraft  700  may include one or more of the embodiments of the shear fitting  300 , which may be incorporated into various portions of the aircraft  700 . In the embodiment shown in  FIG. 8 , an upper support  14   a  supports a plurality of cargo roller trays  12 . The roller trays  12  are joined to upper support  14   a  with shear fittings  300 . Similarly, a lower support  14   b  supports a plurality of cargo roller trays  12 . The cargo roller trays  12  are joined to lower support  14   b  with shear fittings  300 . The embodiment shown in  FIG. 8  may be used in an airplane  700  configured to carry primarily cargo. In an airplane configured to carry passengers, the upper support beam would be configured to support the passenger cabin instead of the cargo roller trays. 
         [0034]    The above-described shear fittings enable joining cargo roller trays to supports. These and other devices described herein may provide significant improvements over the current state of the art, potentially providing for an assembly process with reduced rework. Although the shear fitting has been described in language specific to structural features and/or methodological acts, it is to be understood that the device defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms of implementing the claimed system and method.