Abstract:
A tie down for securing objects in an aircraft having a roller tray can comprise a tie-fitting, a carriage, and protruding elements. A carriage can include at least one side wall with protruding elements extending from the side wall of a carriage to cooperate with a roller tray. The protruding elements removably secure the tie down to a selected location along the roller tray. A restraint extending from an object can be removably secured to a tie down. The tie down being vertically insertable and removable by hand operation and without the use if tools or mechanical fasteners.

Description:
RELATED APPLICATION 
     This application claims the benefit of priority of U.S. Appln. Ser. No. 61/049,872, filed May 2, 2008, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The invention is directed to tie downs for securing cargo in aircraft. 
     BACKGROUND 
     Stabilizing cargo during shipment and minimizing cargo changeover time between shipments are objectives of aircraft cargo transport systems. Typically, cargo shipped by air is first loaded onto specially configured pallets or into specially configured containers, commonly referred to as Unit Load Devices (“ULDs”). To facilitate movement of a ULD within an aircraft cargo compartment as the ULD is loaded, stowed, and unloaded, the deck of an aircraft cargo compartment typically includes a number of raised roller elements. These roller elements often include elongated roller trays that extend longitudinally along the length of the cargo deck, ball panel units, and the like. Once a ULD is in its final stowed position, the ULD must be restrained against both vertical and lateral movement during flight. Accordingly, the deck and sidewalls of a cargo compartment typically include a plurality of restraint devices attached at various installation points located on the deck and sidewalls that engage and secure a ULD. The installation points can be points within or along the elongated roller tray. 
     Two devices typically used to secure ULDs during shipment are primary and supplement restraint devices. Primary restraint devices are stationary and positioned at predetermined installation points on a cargo deck. Installation points coincide with cargo deck locations having features for receiving and retaining a restraint such as recesses, holes, slots, pins, cutouts, roller trays or the like. One example of a primary restraint is a latch that is removably fixed to an installation point and is selectively movable between a deployed (latched) position and a retracted (unlatched) position. The deployed latch receives a restraint, such as a strap. The retracted latch permits movement a ULD during loading and stowage. Primary restraints typically require tools to both engage and remove the restraint from an installation point. In addition, ancillary parts are also required. 
     Supplemental restraints add stability to ULDs and work cooperatively with primary restraint devices. Supplemental devices are moveable, engage a stowed ULD, and can be secured to any location capable of receiving a supplement restraint. Typically, supplemental restraints require tools for engagement and removal from an install point. In addition, ancillary parts may be required. Some have attempted to use the elongated seat track, capable of receiving a supplemental restraint, located adjacent to a roller tray on a cargo deck. Others combine a supplement and primary restraint device in one apparatus. However, ideal supplemental restraints give flexibility to a user to secure ULDs based on the circumstances of loading and stowage. Thus, the attachment of supplemental restraints may be best determined by which location best minimizes lateral or longitudinal movement of a ULD. 
     A need has arisen to develop supplemental restraint devices that augment primary restraints, require minimal tools, do not require ancillary parts, can be removed and secured in minimal time, and can be incorporated into an existing cargo system infrastructure. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a top perspective view of a tie down in a roller tray. 
         FIG. 2  shows a side view of tie down in a roller tray. 
         FIG. 3  shows a top perspective view of a tie down. 
         FIG. 4  is a top view of a tie down. 
         FIG. 5  is a side view of a tie down. 
         FIG. 6  shows a cross-section of  FIG. 5  taken along line  5 - 5 . 
         FIG. 7  is an exploded perspective view of a tie down. 
         FIGS. 8A ,  8 B,  8 C and  8 D show the removal of a tie down from a roller tray. 
         FIG. 9  is a perspective view of strap engaged with a tie down in a roller tray. 
     
    
    
     DESCRIPTION 
     Certain exemplary embodiments of the present invention are described below and illustrated in the accompanying Figures. The embodiments described are only for purposes of illustrating embodiments of the present invention and should not be interpreted as limiting the scope of the invention. Other embodiments of the invention, and certain modifications and improvements of the described embodiments, will occur to those of skill in the art, and all such alternate embodiments, modifications and improvements are within the scope of the present invention. 
       FIGS. 1 and 2  show an embodiment of roller tray  10  and tie down  20 . Longitudinally arranged on a cargo deck in an aircraft, roller tray  10  receives carriage  22  within the opposing first  14  and second  16  rails. Opposing first  14  and second  16  rails extend upwardly from a roller tray base  12 . Openings  18  can be aligned longitudinally down the length of each rail ( 14  and  16 ) at approximately consistent heights above roller tray base  12 . The height and distance between adjacent openings  18  facilitating placement and removal of tie down  20 , as will be discussed below. 
       FIG. 2  shows carriage  22  between opposing first  14  and second  16  rails with protruding elements (elements  50 ,  60  shown in  FIG. 3 ) extending into openings  18 . A carriage  22  thus engages roller tray  10  and can have a fitting  30 . A carriage  22  can have a size less than the distance between any portion of first  14  and second  16  rails that permit its removal from, and placement at, any point along roller tray  10 . Carriage  22  can have first and second side walls,  23 ,  25 , respectively. First and second side walls  23 ,  25 , extend downward from carriage top  21  and engage a portion of first  14  and second  16  rails of roller tray  10 . Fitting  30  on carriage  22  can be designed to receive a restraint such as a strap, chain, rope, cord, braid, cable, or tie. 
     A tie down  20  refers to a device that can receive a restraint. A tie down  20  can include a carriage  22  and fitting  30 . In the embodiment shown, in  FIGS. 2 ,  3  and  4 , fitting  30  can have a track  31 , upper  34  and bottom  35  surfaces, and first  36  and second  37  retaining tabs. First and second retaining tabs,  36 ,  37 , respectively, extend up from and over bottom surface  35  to form upper surface  34 , gap  33  and fitting opening  32 . Fitting opening  32  can have a width about equal to the width of track  31  and can be shaped to receive first  91  or second  92  studs (as will be discussed below). 
     A handle  40  positioned in one parallel embodiment and adjacent to a first side wall  23  of carriage  22  can be movable to engage and/or disengage carriage  22  from roller tray  10  (as shown in  FIGS. 8A ,  8 C,  8 B and  8 D). A roller tray  10 , carriage  22  and fitting  30  can be formed from aluminum, stainless steel, metal alloys, composites structures or other suitable materials. A preferable material for carriage  22  can be aluminum 7136-TZ651 1, having an anodized finish, as is known in the art. 
     One embodiment combines fitting  30  on carriage  22  and protruding elements  50 ,  60 ,  70  and  80  to secure a restraint to roller tray  10  as shown in  FIGS. 3 ,  4 ,  5  and  7 . Protruding elements  50 ,  60 ,  70  and  80  engage openings  18  to removeably secure carriage  22  to roller tray  10 . A combination of movable ( 50 ,  60 ) and fixed ( 70 ,  80 ) protruding elements allow a user to selectively move and secure carriage  22  to roller tray  10 . A protruding element refers to a projection that is capable of engaging an opening. As shown in  FIGS. 3 through 6 , carriage  22  can have first  50  and second  60  moveable protruding elements extending through a first side wall  23  to engage openings  18  in a first rail  14  of roller tray  10 . First  50  and second  60  movable protruding elements can be positioned in first side wall  23  at about the same height above the base of first side wall  23  of carriage  22 . The height of first  50  and second  60  movable protruding elements above the base of first side wall  23  can be about equal to the height of openings  18  above roller tray base  12 . The distance between first  50  and second  60  movable protruding elements can be about equal to the distance between two adjacent openings  18  on a first rail  14  of roller tray  10 . Thus, the moveable protruding elements  50  and  60  can be designed to engage openings  18  of roller tray  10 .  FIGS. 3 ,  4 ,  5  and  6  show two movable protruding elements, however, the inventors contemplate that more or less than two movable protruding elements can be used. For example, three, four or more moveable protruding elements can be used. In addition, moveable protruding elements ( 50 ,  60 ) can be used on either first side wall  23  or a second side wall  25 . The protruding elements ( 50 ,  60 ,  70  and  80 ) can be formed from aluminum, stainless steel, metal alloys, composites structures or other suitable material. A preferable material for protruding elements can be aluminum 713 6-TZ65 11 having an anodized finish, as is known in the art. 
     As shown in  FIGS. 6 and 7 , first  50  and second  60  moveable protruding elements can work cooperatively with handle  40 . For the purposes of clarity, a first moveable protruding element  50  and its cooperation with handle  40  will be discussed, however its configuration and operation can be applied to second movable protruding element  60  or as many moveable protruding elements as desired. A first moveable protruding element  50  can have two ends, a securing end  55  and an engaging end  56 . The securing end  55  extends into cavity  51  through first side wall  23  into handle  40  and secured to the interior of first pull cap  41 . Within cavity  51 , a spring  53  encircles first moveable protruding element  50  and applies a force against both cavity wall  52  and engaging end  56  of moveable protruding element  50 . A first pull cap  41  can have a first pull cap ridge  43  that engages the outer surface of a handle  40 . As discussed above, second protruding elements  60  can be similarly configured. Thus, first  50  and second  60  moveable protruding elements can be secured to first  41  and second  45  pull caps which engage handle  40 . A user can apply a force orthogonal to handle  40  towards opposing second side wall  25  which pulls movable protruding elements  50  and  60  through the first side wall  23  into a retracted position. Springs  53  and  63  counter the force exerted on handle  40 , upon removal movable protruding elements  50  and  60  return to an engaged position, extending past the outer surface of first side wall  23 . 
     A user can retract handle  40  pulling first  50  and second  60  moveable protruding elements approximately below or flush with the outer surface of first side wall  23 . So positioned, carriage  22  can be placed in roller tray  10 . Upon placement of carriage  22  in roller tray  10 , handle  40  can be released, allowing moveable protruding elements  50  and  60  to engage roller tray  10 . First  50  and second  60  moveable protruding elements can be retracted by hand operation without the use of tools of mechanical fasteners. Handle  40 , first  41  and second  45  pull caps can be formed from a variety of thermoplastic and thermoset materials. A preferable material can be nylon. 
     First  50  and second  60  movable protruding elements can have an engaging ends ( 56 ,  66 ) in any form of a projection extending out from the surface of a first side wall  23 . For example, movable protruding elements  50  and  60  can have engaging ends  56  and  66 , that can be a cylinder, cone, frustocone, pyramid, frustopyramid, a cuboid, cube, semi-sphere or a dome. 
     The inventors contemplate other methods to maintain first  50  and second  60  moveable protruding elements in an engaged position through first side wall  23  and roller tray  10 . In one embodiment, a latch can be rotatably attached to the side of a carriage  22  to secure handle  40  and thus moveable protruding elements  50  and  60  in an engaged position. In yet another embodiment, a carriage can have a pivotable side wall, the side wall having fixed protruding elements to engage the roller tray  10 . 
     As described above, second side wall  25  opposes and can be parallel to first side wall  23  of carriage  22 . Extending out from second side wall  25  can be first  70  and second  80  fixed protruding elements. First  70  and second  80  fixed protruding elements can engage openings  18  on second rail  16  of roller tray  10 . Fixed protruding elements  70  and  80  can be any projection extending out from the surface of second side wall  25 . For example, first  70  and second  80  fixed protruding elements  70  and  80  can be a cylinder, cone, frustocone, pyramid, frustopyramid, a cuboid, cube, semi-sphere or a dome. First  70  and second  80  fixed protruding elements can be removably fixed to second side wall  25  using screws, fasteners, bolts or the like. In another embodiment, first  70  and second  80  fixed protruding elements form a single integral structure with second side wall  25  of carriage  22 . First  70  and second  80  fixed protruding elements can be positioned at approximately the same height above the base of second side wall  25  of carriage  22 . The distance between first  70  and second  80  fixed protruding elements can be about equal to the distance between two adjacent openings  18  on a second rail  16  of roller tray  10 . The height of first  70  and second  80  fixed protruding elements above the base of second side wall  25  can be about equal to the height of the openings  18  on a second rail  16  above roller tray base  12 . 
     As shown in  FIGS. 8A ,  8 B,  8 C and  8 D, tie down  20 , carriage  22 , fitting  30  and protruding elements  50 ,  60 ,  70  and  80  removably secure a restraint to a selected location along roller tray  10 . Removably securing tie down  20  to a selected location along roller tray  10  can be completed by hand operation carriage  22  without the use of tools of mechanical fasteners can be placed in roller tray  10  by pulling handle  40  towards the second side wall  25  retracting movable protruding elements  50  and  60  approximately flush with the outer surface of first side wall  23 . Retracted movable protruding elements  50  and  60  facilitate placement of carriage  22  in a roller tray  10 . As fixed protruding elements  70  and  80  engage openings  18  on second rail  16 , first side wall  23  of carriage  22  can be placed adjacent to first rail  14 . Handle  40  can be released, springs  53  and  63  pushing first  50  and second  60  (not shown) moveable protruding elements through a first side wall  23  and openings  18  of first rail  14 . Thus, protruding elements engage roller tray  10  by hand operation and without the use of tools or mechanical fasteners. As shown in  FIG. 8A , carriage  22  and protruding elements  50  and  60  ( 70  and  80  not shown) engage openings  18  on first  14  and second  16  rails of roller tray  10 . A user can slide handle  40 , towards a first side wall  23  disengaging first  50  and second  60  (not shown) moveable protruding elements from openings  18 . As shown in  FIGS. 8C and 8D , by pulling carriage  22  in an upwardly direction from roller tray base  12 , fixed protruding elements  70  and  80  are disengaged from openings  18  on second rail  16 . 
     Tie down  20  can secure a variety of restraints to roller tray  20 . For example, a restraint can include a chain, rope, cord, braid, cable, tie or a strap  98 . An embodiment is shown in  FIG. 9  where a fitting  30  on tie down  20  removably secures strap  98  to roller tray  10 . Fitting  30  receives a strap  98  through an engaging apparatus  90 . A ring opening  96  positioned on engaging apparatus  90  receives a ring  97 . Strap  98  encircles a portion of ring  97  securing a stowed ULD to engaging apparatus  90  and fitting  30 . Strap  98  can be adjusted to increase tension between the engaging apparatus  90  and the ULD for stowage and shipment. 
     As shown in  FIG. 9 , engaging apparatus  90  can have first  91  and second  92  studs extending downwardly to engage a track  31  of tie down  30 . The track  31 , first  91  and second  92  studs can conform to Military Specification 33601, May 1988 Revision, wherein the shape and profile of track  31  and studs ( 91 ,  92 ) are incorporated herein by reference. First and second studs ( 91 ,  92 ) comprise a main and disc portions. A main portion extends from the engaging apparatus  90  with a disc portion distal to the main portion opposite engaging apparatus  90 . A disc portion can have a diameter greater than the main portion. However, first and second studs ( 91 ,  92 ) correspond to track  31  of fitting  30 . The distance between first  91  and second  92  studs approximates the distance between two consecutive fitting openings  32  on a fitting  30 . So positioned, the first fitting openings  32  can receive first  91  and second  92  studs of engaging apparatus  90 . Engaged inside fitting openings  32 , engaging apparatus  90  can be laterally moved so that the disc portion of first  91  and second  92  studs are positioned under first  36  and second  37  retaining tabs and upper surface  34  of track  31 . 
     An engaging apparatus  90  can include a shear stud  95 , as is known in the art. A shear stud  95  has an opening designed to receive a portion of engaging apparatus  90 . As the engaging apparatus  90  is moved into a position where first  91  and second  92  studs engage track  31  and retaining tabs  36  and  37 , a shear stud  95  can be placed over engaging apparatus  90  and into the remaining area available in fitting openings  32 . Because shear stud  95  can be positioned within consecutive retaining tabs  36  and  37  of tie down  30 , shear stud  95  minimizes lateral movement of engaging apparatus  90  inside track  31 . So positioned, lateral movement of engaging apparatus  90  over carriage  22  and thus roller tray  10  can be minimized, and a stowed ULD can be removably secured to a selected location along a roller tray  10 . 
     A method of using a tie down  20  in a roller tray  10  is also an aspect of the invention. A ULD can be loaded onto a cargo deck. An installation point for carriage  22  can be identified in a roller tray  10 . As shown in  FIGS. 8A ,  8 B,  8 C and  8 D, carriage  22  can be removably secured to a selected installation point in roller tray  10  by first pulling handle  40  to retract moveable protruding elements  50  and  60 . Fixed protruding elements  70  and  80  can engage openings  18  on a second rail  16  of roller tray  10 . A first side wall  23 , with retracted moveable protruding elements  50  and  60 , can be positioned adjacent to a first rail  14  of roller tray  10 . A handle  40  can be released to engage moveable protruding elements  50  and  60  with 15 openings  18  of first rail  14  of roller tray  10 . A restraint can be secured to fitting  30  on carriage  22 . During unloading of a shipment a ULD, a restraint can be disengaged from fitting  30 . As shown in  FIG. 8A  handle  40  can be pulled towards second side wall  25 , retracting moveable protruding elements  50  and  60 , just above, below, or flush with the outer surface of first side wall  23 . With moveable protruding elements  50  and  60  retracted, or partially retracted, carriage  22  can be lifted upwardly from roller tray  10 , as shown in  FIGS. 8B ,  8 C and  8 D. 
     The above descriptions of various embodiments of the invention are intended to describe and illustrate various elements and aspects of the invention. Persons of ordinary skill in the art will recognize that certain changes and modifications can be made to the described embodiments without departing from the scope of the invention. All such changes and modifications are intended to be within the scope of the appended claims.