Abstract:
A multi-purpose tray including a front, a back, a first side, a second side, and a bottom. The tray can include beams extending from the front of the tray and slots defined in the back of the tray. When two trays are stacked in opposite directions with respect to one another, the beams are received by the slots. The tray also includes a domed bottom. The domed bottom has a convex profile with respect to the interior of the tray and can include transverse ribs or longitudinal ribs. The tray also includes drain apertures positioned along the front and back of the tray. The drain apertures can enhance cleaning of the tray by communicating fluid from channels defined by the front and back. The tray also includes a stop for projection for limiting sliding movement of a top tray relative to a bottom tray when two trays are stacked in a similar orientation with respect to one another. The tray also includes handles in the first and second side and a gripping portion on one of the first and second handles.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of the Provisional Patent Application No. 60/367,688 for a STACKABLE TRAY HAVING AN ANTI-PIVOT STOP AND WASH APERTURES, filed on Mar. 26, 2002. This claim is made under 35 U.S.C. § 119(e) and 37 C.F.R. § 1.53(c)(3). 

   FIELD OF THE INVENTION 
   This invention generally relates to multi-purpose reusable load-bearing trays and, more specifically, to trays adapted to be nestable or stackable in three positions. 
   BACKGROUND OF THE INVENTION 
   Plastic trays that are stackable and/or nestable can be desirable to maintain cargo such as material and/or products. However, existing trays are not as efficient as desired. Specifically, existing trays can require excessive handling time and cleaning time. Also, the existing trays may not nest together as well as desired. An improved tray is needed. 
   SUMMARY OF THE INVENTION 
   The present invention provides an improved tray for maintaining cargo during transport. The tray of the present invention can include one or more drain apertures disposed along a front or back of the tray. The drain aperture can improve the efficiency of the tray by improving the cleaning of the tray. In particular, the structure of the existing trays can define blind holes and pockets in which debris and/or vermin can accumulate. Positioning a drain aperture adjacent the blind holes or pockets of the tray can enhance the likelihood that the debris can be quickly removed during cleaning. The drain aperture can be disposed along any surface of the front or back of the tray and can be defined, at least in part, by ribs disposed between a wall and an apron of the front or back of the tray. The ribs can be any shape as desired, including arcuate, straight, cross-shaped, or T-shaped. A drain aperture can also be formed in a notch defined in the front or back of the tray; the notch being used for aligning two trays during stacking. 
   The present invention also provides a tray with a domed bottom. The bottom of the tray can be convex with respect to the interior of the tray. The domed shape of the bottom of the tray can enhance the strength of the tray. The bottom can also include at least one transverse and/or at least one longitudinal rib to enhance the strength of the bottom. The bottom can be formed with a convex or concave profile. 
   The present invention also provides a tray with two handles where one of the handles includes a gripping portion. By disposing a gripping portion on only one of the handles, a user of the tray can quickly identify the orientation of the tray. The efficiency of the tray is enhanced when a user can quickly identify the orientation of the tray during stacking the of trays. 
   The present invention also provides ribs disposed in a pocket of a bottom tray for receiving and engaging feet of a top tray. The ribs can enhance the alignment of two trays stacked relative to each other and support a top tray during sliding movement relative to a bottom tray. A rib closest to the center of the tray can be tapered to reduce the likelihood that a top tray will bind relative to a bottom tray when the two trays are being engaged. 
   The present invention also provides a stop having a ramp shape positionable in a channel of the tray. When a top tray is engaged with a bottom tray, the top tray is slidingly received by a channel of the bottom tray. The stop disposed in the channel can limit the movement of the top tray relative to the bottom tray when the trays are being engaged with respect to one another. A ramped portion of the stop can enhance the efficiency of the tray by ensuring that sliding movement of the trays will only be prevented in only one direction. 
   The present invention also provides a tray having beams disposed on a front of the tray and corresponding slots formed in the rear of the tray. The corresponding beams and slots can permit two trays to be stacked on top of one another when in a similar orientation. The support of the top tray relative to the bottom tray, when two trays are stacked in similar orientation, does not occur at the outermost edges of the front corners of the trays. The beams can be received by the slots when two trays are stacked in an opposite direction relative to one another. 
   Other applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
       FIG. 1  is a perspective view of a tray according to a first embodiment of the invention; 
       FIG. 2  is a cross-sectional view of a front of the tray according to the first embodiment of the invention; 
       FIG. 3  is a top plan view of the tray according to the first embodiment of the invention; 
       FIG. 4  is a partial cross-sectional and perspective view of the tray according to the first embodiment of the invention showing the configuration of ribs between the wall and the apron; 
       FIG. 5  is a detailed partial perspective view of a front corner of the tray according to the first embodiment of the invention; 
       FIG. 6  is a partial detailed perspective view of a rear corner of the tray according to the first embodiment of the invention; 
       FIG. 7  is partial detailed perspective view of the rear corner of the tray according to the first embodiment of the invention; 
       FIG. 8  is a detailed top plan view of a second side of the tray according to the first embodiment of the invention; 
       FIG. 9  is a detailed perspective view of a rear corner of a tray according to the first embodiment of the invention; 
       FIG. 10  is a front plan view of two trays according to the first embodiment of the invention stacked in a similar orientation with respect to one another; 
       FIG. 11  is a rear plan view of two trays according to the first embodiment of the invention stacked at an angle of 90° relative to one another; 
       FIG. 12  is a rear plan view of two trays according to the first embodiment of the invention stacked at an angle of 180° relative to one another; 
       FIG. 13  is a side plan view of two trays according to the first embodiment of the invention stacked in a similar orientation with respect to one another; 
       FIG. 14  is a side plan view of two trays according to the first embodiment of the invention stacked at an angle of 180° relative to one another; 
       FIG. 15  is a perspective view of a tray according to a second embodiment of the invention; 
       FIG. 16  is a detailed partial cross-sectional view of a front of the tray according to the second embodiment of the invention showing the ribs; 
       FIG. 17  is a top plan view of the tray according to the second embodiment of the invention; 
       FIG. 18  is a partial detailed view of the front corners of two trays according to the second embodiment of the invention; 
       FIG. 19  is a partial detailed view of a rear corner of the tray according to the second embodiment of the invention; 
       FIG. 20  is a front plan view of two trays according to the second embodiment of the invention stacked in a similar orientation with respect to one another; 
       FIG. 21  is a plan view of two trays according to the second embodiment stacked at an angle of 180° relative to one another; 
       FIG. 22  is a side plan view of two trays according to the second embodiment of the invention stacked in a similar orientation with respect to one another; 
       FIG. 23  is a side plan view of two trays according to the second embodiment of the invention stacked at an angle of 180° relative to one another; 
       FIG. 24  is a front plan view of two trays according to the second embodiment of the invention stacked at an angle of 90° relative to one another; and 
       FIG. 25  is a schematic view of a tray according to the invention having a domed bottom. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Various embodiments of the present invention are shown throughout the figures. These figures include common elements in different structural configurations. Common elements are designated with a common base numeral and differentiated with a alphabetic designation. 
   Referring now to  FIG. 1 , the present invention provides a multipurpose tray  10 . The tray  10  can include a front  12 , a rear  14 , a first side  16 , a second side  18 , and a bottom  20  which can be integrally formed with respect to one another. The tray  10  can be fabricated from plastic in an injection molding process.  FIG. 15  shows another embodiment of the invention, a tray  10   a  having a front  12   a,  a rear  14   a,  a first side  16   a,  a second side  18   a,  and a bottom  20   a  which can be integrally formed with respect to one another. 
   Referring now to  FIGS. 1 and 2 , the front  12  can extend from the first side  16  to the second side  18  and can include a wall  22 , a fillet  24  and an apron  26 . The wall  22 , fillet  24  and apron  26  can define a channel  28 . The front  12  can also include a right-hand portion  30  and a left-hand portion  32  which are mirror images of one another with respect to a substantially vertical center axis  186  of the front  12 , as best seen in FIG.  10 . 
   Referring now to  FIG. 3 , the fillet  24  can define an opening  34 . The opening  34  can be centered along the axis  186  of the front  12  with respect to the right-hand portion  30  and the left-hand portion  32 . The opening  34  can include a bottom surface  36  and side surfaces  38  and  40 . In a second embodiment of the invention, an opening  34   a  is shown in perspective view in  FIG. 15 , in partial detailed cross-sectional view in  FIG. 16 , and in overhead plan view in FIG.  17 . The opening  34   a  can be defined by a fillet  24   a  of a front  12   a  of tray  10   a.  The opening  34   a  can include bottom surface  36   a,  side surfaces  38   a  and  40   a  as well as secondary bottom surfaces  36   b  and  36   c  and secondary side surfaces  38   b  and  40   b.    
   Referring now to  FIG. 5 , the fillet  24  can also define a boss  42 , a notch  44 , a gain  46 , and a dimple  48 . The boss  42  is positioned along the length of the front  12  between the opening  34  and the notch  44 . The boss  42  includes a support surface  50 . A projection  52  can extend from the fillet  24  between the notch  44  and the gain  46 . The dimple  48  can be positioned at an outermost edge of the front  12 . An alternative embodiment of the dimple  48   a  is shown extending a height of an apron  26   a  of the tray  10   a  in  FIGS. 17 ,  18  and  20 . 
   Referring now to  FIGS. 1-5 , fillet  24  can be pierced by one or more apertures  54 . A plurality of apertures  54  can be evenly spaced along the length of the front  12 . The apertures  54  can be formed in the bottom surface  36  of the opening  34 , the side surfaces  38  and  40  of the opening  34 , or in the notch  44 . The apertures  54  can enhance cleaning of the tray  10  by reducing the likelihood that vermin or debris will become trapped in the channel  28 . 
   Referring now to  FIG. 4 , ribs can be disposed in the channel  28  to define a plurality of apertures and to enhance the structural integrity of the tray  10 . Referring to  FIG. 5 , ribs  56 ,  58 ,  60  and  62  can be formed in various shapes and be disposed at various positions relative to the opening  34 . As shown in  FIG. 16 , ribs  64 ,  66 ,  68  and  70  can be positioned adjacent a side surface  38   a,  a secondary bottom surface  36   b  and a bottom surface  36   a  or any combination thereof. 
   Referring now to  FIG. 5 , the front  12  also includes a wall  22 . The wall  22  can define a foot  72  and shoulder  74 . The foot  72  can be shaped to correspond to the shape of the notch  44 . Also, the foot  72  is substantially vertically aligned with the notch  44 . The shoulder  74  will be described in greater detail below.  FIG. 18  shows a front wall  12   a  of a tray  10   a  having wall  22   a  that defines a foot  72   a  and shoulder  74   a.  The foot  72   a  is shaped to correspond to the shape of the notch  44   a  and is substantially vertically aligned with the notch  44   a.    
   Referring again to  FIG. 5 , a beam  76  extends from wall  22  generally toward the apron  26 . The beam  76  does not extend past the apron  26 . The beam  76  can be tapered such that the beam  76  is narrowest immediately adjacent the foot  72 . The beam  76  is substantially vertically aligned with the support surface  50 .  FIG. 18  shows a front  12   a  having a beam  76   a  substantially vertically aligned with the support surface  50   a  of a boss  42   a.    
   Referring now to FIGS.  1  and  6 - 9 , the rear  14  of the tray  10  can be substantially similar to the front  12  of the tray  10 . The rear  14  can include a wall  22   b,  a fillet  24   b,  and an apron  26   b.  The fillet  24   b  can define an opening  34   b,  including bottom surface  36   d  and side surfaces  38   c  and  40   c,  and a boss  42   b.  One or more apertures  54  can pierce the fillet  24   b  along the surface  36   d,  or a notch  44   b.  The rear  14  also includes a slot  78 . The slot  78  extends vertically downward from the boss  42   b  along the wall  22   b.  The slot  78  can be tapered to be narrowest at a position furthest from the boss  42   b.  The slot  78  is substantially aligned with the beam  76  of the front  12  to receive a beam  76  when two trays  10  are stacked 180° relative to another. The stacking of two trays relative to one another will be described in greater detail below. The rear  14  does not include beams extending from the wall  22   b  as best seen in FIG.  9 . Also, the rear  14  may not include a dimple  28  as formed in the front  12 . 
     FIGS. 15 and 19  show the rear  14   a  of alternative embodiment of the invention. The rear  14   a  can be substantially similar to the front  12   a  of the tray  10   a.  The rear  14   a  can include a wall  22   c,  a fillet  24   c,  and an apron  26   c.  The fillet  24   c  can define an opening  34   c,  including bottom surfaces  36   e,    36   f  and  36   g  as well as side surfaces  38   d,    38   e  and  40   d,    40   e  and a boss  42   c.  One or more apertures  54  can pierce the fillet  24   c  along the surfaces  36   e,    36   f,    36   g,    38   d,    38   e,    40   d  and  40   e,  or a notch  44   c.  The rear  14   a  also includes a slot  78   a.  The slot  78   a  extends vertically downward from the boss  42   c  along the wall  22   c.  The slot  78   a  can be tapered to be narrowest at a position furthest from the boss  42   c.  The slot  78   a  is substantially aligned with the beam  76   a  of the front  12   a  to receive a beam  76   a  when two trays  10   a  are stacked 180° relative to another. The stacking of two trays relative to one another will be described in greater detail below. The rear  14   a  does not include beams extending from the wall  22   c  as best seen in FIG.  15 . Also, the rear  14   a  may not include a dimple  28   a  as formed in the front  12   a.    
   Referring now to  FIGS. 1 ,  3 ,  5  and  8 , the second side  18  can include an inner face  80 , an outer face  82 , a top portion  84  and a bottom portion  86 . The inner face  80  can be defined by an innermost surface  88 , a front pocket  90  and a rear pocket  92 . The front and rear pockets  90  and  92  can be defined by inwardly facing surfaces  96  and  98 , front facing surfaces  100  and  102 , rear facing surfaces  104  and  106 , and upper facing surfaces  108  and  109 , respectively. The inwardly facing surfaces, the front facing surfaces, the rear facing surfaces and the upper facing surfaces of each pocket define openings  110  and  112  in the front and rear pockets  90  and  92 . The pockets  90  and  92  are shaped to substantially correspond to the shape of mating feet disposed on the outer face  82  of the second side  18 . The feet will be described in greater detail below. 
   Referring now to  FIGS. 6 and 7 , one or more ribs  114  can be disposed on the inwardly facing surface  98  of the rear pocket  92 . The ribs  114  are generally arcuate or semi-circular in cross section. A rib  116  positioned closest to the center of the second side  18  can be tapered, such that a radius of the rib  116  is greater than a radius of the ribs  114 . The rib  116  and ribs  114  can project from the surface  98  the same distance. Tapering the rib  116  and enhances the sliding interaction between two trays  10  to be stacked relative to one another. Specifically, it has been found that when the rib  116  is shaped without a tapered semi-circular cross section, a top tray sliding relative to a bottom tray can bind. 
   Referring now to  FIGS. 5 ,  9  and  1 , the outer face  82  of the second side  18  can include a honeycomb section  118 , a front foot  120  and a rear foot  122 , and an outwardly facing surface  124 . The honeycomb section  118  can be disposed adjacent to the top portion  84  of the second side  18 . The honeycomb section  118  enhances the strength and rigidity of the tray  10 . Opposite of the front pocket  90  of the inner face  80  a planar surface  126  is disposed on the outer face  82 . Numerical and alphabetic information can be molded or formed on the surface  126 . Runners  128  and  130  extend downwardly toward the bottom portion  86  from the honeycomb section  118 . 
   Referring now to  FIGS. 5 and 9 , the front foot  120  and a rear foot  122  extend from the outwardly facing surface  124  of the outer face  82 . The feet  120  and  122  include runners  132  and  134  respectively. The feet  120  and  122  can be honeycombed. The front foot  120  is shaped to correspond to the shape of the rear pocket  92 . The rear foot  122  is shaped to correspond to the shape of the front pocket  90 . The front foot  120  can be defined in part by an outer surface or plane  136 , best seen in FIG.  5 . The rear foot  122  can be defined by two outer surfaces or planes  138  and  140 . The surfaces  138  and  140  are disposed at an angle of greater than 0° relative to one another. 
   Referring now to  FIGS. 1 ,  5  and  8 , the top portion  84  of the second side  18  is defined by a plurality of upper facing surfaces  142 ,  144 ,  146 ,  148 ,  150 ,  152 ,  154 , and  156 . Surfaces  144  and  148  are downwardly recessed with respect to surface  142 . Surfaces  142 ,  146  and  150  are substantially co-planar. Surfaces  152 ,  154  and  156  define the bottom surface of a discontinuous channel  158  extending along the top portion  84  of the second side  18  between the front  12  and the rear  14 . The channel  158  is longitudinally aligned with the gain  46  of the front  12  and a gain  46 a of the rear  14 . A stop  160  is disposed in the channel  158 . The stop  160  can be shaped like a ramp with a substantially vertical side facing toward the front  12  and a substantially ramped side facing the rear  14 . The stop  160  can prevent movement of a top tray relative to a bottom tray when two trays are to be stacked in a similar orientation and slidingly engaged in a first direction as will be discussed in greater detail below. The first direction is defined when the front of a top tray is engages the rear of the bottom tray at the beginning of the sliding engagement. The second direction is defined when the rear of the top tray is received by front of the bottom tray during the beginning of the sliding engagement. Surface  152  is downwardly recessed with respect to surface  154  and a rounded shoulder  162  can be defined therebetween. 
   Referring now to  FIG. 9 , the bottom portion  86  of the second side  18  includes two longitudinal rails  164  and  166  that extend between opposite edges of the foot  72  of the front  12  to a foot  72   b  of the rear  14 . Transverse rails  168  can be randomly or evenly spaced between the rails  164  and  166  along the length of the second side  18 . 
   Referring now to  FIGS. 1 and 3 , the first side  16  and the second side  18  are substantially mirror images of one another with respect to a longitudinal axis  190 . However, the sides  16  and  18  are different in that a configuration of a handle  170  of the second section  18  is different than a configuration of a handle  172  of the first section  16 . Specifically, one of the handles  170  and  172  includes a gripping portion  174 . The gripping portion includes one or more rounded projections extending into a cavity defined by the handle.  FIGS. 1 and 3  illustrate a gripping portion  174  having one rounded projection extending from handle portion  172 . However, the gripping portion can extend from the handle portion  170  and can include more than one rounded projection.  FIG. 15  illustrates a gripping portion  174   a  including a plurality of rounded projections. 
   Referring to  FIGS. 1 ,  3  and  15 , the gripping portions  174  and  174   a  generally conform to the hand of a user of the tray  10  or tray  10   a.  The gripping portion  174  can be advantageous to indicate to a human handler the orientation of the tray. For example, if the trays are to be stacked at 180° relative to one another, the human handler can grasp a tray to be stacked and recognize whether the tray can be placed on top of a stack of trays or must be oriented differently before the tray is stacked by feeling the gripping portion instead of having to examine the sides of the tray to identify the location of the beam  76  of the tray being held and the slot  78  of the tray at the top of the stack of trays. Specifically, when trays are to be stacked at 180° relative to one another, the human handler will recognize that every other tray must be grasped so that the gripping portion is felt with a particular hand. When the trays are to be stacked at 0° relative to one another, the human handler will recognize that every tray must be grasped so that the gripping portion is felt with a particular hand. 
   Referring now to  FIGS. 15 ,  17  and  22 , the first side  16   a  and second side  18   a  of the tray  10   a  according to an alternative embodiment of the invention can be substantially similar to the first side  16  and second side  18  of the tray  10 , respectively. The first side  16   a  and second side  18   a  can be mirror images of one another about a longitudinal axis  198 . Each side can include an inner face  80   a,  an outer face  82   a,  a top portion  84   a  and a bottom portion  86   a.  The inner face  80   a  can be defined by an innermost surface  88   a,  a front pocket  90   a  and a rear pocket  92   a.  The front and rear pockets  90   a  and  92   a  can be defined by inwardly facing surfaces  96   a  and  98   a,  front facing surfaces  100   a  and  102   a,  and rear facing surfaces  104   a  and  106   a,  respectively. The rear pocket  92   a  can include an upper facing surface  109   a.  The inwardly facing surfaces, the front facing surfaces, the rear facing surfaces and the upper facing surfaces of each pocket define openings  110   a  and  112   a  in the front and rear pockets  90   a  and  92   a.  The pockets  90   a  and  92   a  are shaped to substantially correspond to the shape of mating feet disposed on the outer face  82   a.  The feet will be described in greater detail below. 
   Referring now to  FIG. 22 , the outer face  82   a  can include a honeycomb section  118   a,  a front foot  120   a  and a rear foot  122   a,  and an outwardly facing surface  124   a.  The honeycomb section  118   a  can be disposed adjacent to the top portion  84   a  of the second side  18   a.  The honeycomb section  118   a  enhances the strength and rigidity of the tray  10   a.  Opposite of the front pocket  90   a  of the inner face  80   a  a planar surface  126   a  is disposed on the outer face  82   a.  Numerical and alphabetic information can be molded or formed on the surface  126   a.  Runners  128   a  and  130   a  extend downwardly toward the bottom portion  86   a  from the honeycomb section  118   a.    
   Referring now to  FIGS. 15 and 24 , the front foot  120   a  and a rear foot  122   a  extend from the outwardly facing surface  124   a  of the outer face  82   a.  The feet  120   a  and  122   a  include runners  132   a  and  134   a  respectively. The feet  120   a  and  122   a  can include ribs  200 . The front foot  120   a  is shaped to correspond to the shape of the rear pocket  92   a.  The rear foot  122   a  is shaped to correspond to the shape of the front pocket  90   a.  The front foot  120   a  can be defined in part by an outer surface or plane  136   a.  The rear foot  122   a  can be defined by two outer surfaces or planes  138   a  and  140   a.  The surfaces  138   a  and  140   a  are disposed at an angle of greater than 0° relative to one another. 
   Referring now to  FIG. 17 , the top portion  84   a  is defined by a plurality of upper facing surfaces  142   a,    144   a,    146   a,    148   a,    150   a,    152   a,    154   a,  and  156   a.  Surfaces  144   a  and  148   a  are downwardly recessed with respect to surface  142   a.  Surfaces  142   a,    146   a  and  150   a  are substantially co-planar. Surfaces  152   a,    154   a  and  156   a  define the bottom surface of a discontinuous channel  158   a  extending along the top portion  84   a  between the front  12   a  and the rear  14   a.  The channel  158   a  is longitudinally aligned with the gain  46   b  of the front  12   a  and a gain  46   c  of the rear  14   a.  Surface  152   a  is downwardly recessed with respect to surface  154   a  and a shoulder  162   a  can be defined therebetween. 
   Referring now to  FIGS. 15 ,  20  and  21 , the bottom portion  86   a  of each side of the tray  10   a  can be substantially similar to the bottom portion of each side of the tray  10 . Specifically, each bottom portion of the first and second sides  16   a  and  18   a  can include two longitudinal rails that extend between opposite edges of the foot  72   a  of the front  12   a  to a foot  72   c  of the rear  14   a.  Transverse rails can be randomly or evenly spaced between the longitudinal rails along the length of the first and second sides  16   a  and  18   a.    
   Referring now to  FIGS. 1 ,  3 ,  8  and  25 , a bottom  20  of the tray  10  can define a lattice pattern. The bottom  20  can also include longitudinal ribs  176  and transverse ribs  178 . The bottom  20  can also be domed to increase the strength of the tray  10  and reduce the material required to form the bottom  20 . The bottom  20   a  of tray  10   a  can be domed. The shape of a domed bottom surface is shown schematically in FIG.  25 . The front and sides of the tray are shown in phantom and a line  180  illustrates a profile of the bottom  20  along the transverse direction. Line  182  illustrates that the bottom can also be arched along the longitudinal direction. Line  188  illustrates a profile of a bottom that is not domed. The dome configuration of a bottom can increase the strength of the bottom by fifty percent. Tray  10   a  can include a domed bottom  20   a.  The enhanced strength of a domed-shaped bottom  20  can also reduce the amount of material necessary to form the bottom  20  when a predetermined strength is required. 
   Preferably, the dome is three-eights (⅜) of one inch at the center of the bottom  20 . In other words, the center of the dome extends toward the interior of the tray  10  three-eights (⅜) of one inch relative to the intersection of the bottom with the sides  16  and  18 , and the front  12  and rear  14 . However, the height of the dome can be increased or decreased as desired. The height of the dome can be varied based on the weight of the material and/or products to be maintained in the tray  10 . In particular, the dome can be completely or partially flattened relative to the intersection of the bottom  20  and with the sides  16  and  18 , and the front  12  and rear  14  in response to a weight of the cargo to be maintained by the tray  10 . The height of the dome can be determined based on the projected flattening of the dome in response to weight of the cargo to be maintained by the tray  10 . 
   Two or more trays can be stacked on top of one another in three different configurations. The height of two stacked trays in each configuration can be different. The trays can be blind stacked and unstacked. The engagement of two trays  10  and two trays  10   a  is substantially similar. 
   In a first configuration, a bottom tray  10  and a top tray  10  are stacked in the same orientation, or at an angle of 0° relative to one another. In the first configuration, the second side  18  of the top tray engages the second side of the bottom tray.  FIG. 10  is a front plan view of two trays stacked in the same orientation and  FIG. 13  is a side plan view of two trays stacked in the same orientation. When two trays are stacked in a similar orientation, a foot  72   a  of a rear  14  of an upper tray is received by the notch  44  of the front  12  of a lower tray. The trays are moved relative to one another and a runner  134  of the upper tray enters the gain  46  of the front  12  of the lower tray and slides along the channel  158 . An edge  184  of the rear foot  122  slidingly contacts surface  142  of the second side  18  of the lower tray. The runner  134  of the rear foot  122  engages the tapered rib  116  and moves past the rib  116  and ribs  114 . The runner  132  of the top tray enters the gain  46  of the lower tray. The sliding motion of the top tray relative to the bottom tray stops when the runner  134  contacts or abuts the stop  160  of the lower tray. As shown in  FIG. 10 , when the upper tray is stacked relative to the lower tray in the same orientation, a beam  76  of the top tray contacts the support surface  50  of the boss  42  of the lower tray, the runner  132  of the upper tray engages the surface  152  of the lower tray, the runner  134  of the upper tray engages the surface  156  of the lower tray, and the edge  184  of the upper tray engages the surface  142  of the lower tray and the ribs  114  and  116 . Substantially the same engagement occurs between the first side  16  of the top tray and the first side  16  of the lower tray. 
   In a second configuration, a bottom tray and a top tray are stacked in the opposite orientation, or at an angle of 180° relative to one another. In the second configuration, the first side  18  of the top tray engages the second side of the bottom tray.  FIG. 12  is a front plan view of two trays stacked in the same orientation and  FIG. 14  is a side plan view of two trays stacked in the same orientation. A foot  72  of the front  12  of the top tray enters the notch  44  of a lower tray. A runner  132  enters the gain  46  of the lower tray and slidingly contacts the surfaces  152  and  154  of the channel  158 . A runner  134  enters the gain  46 . When the front and rear feet  120  and  122  of the top tray are aligned with the rear and front pockets  92  and  90 , respectively, of the bottom tray, the top tray drops into engagement with the bottom tray. The ribs  114  engage surface  136  to reduce the likelihood that the top tray will move relative to the bottom tray. When the top and bottom tray are engaged at an angle of 180° relative to one another, a beam  76  of the top tray is slidingly received in the channel  78  (shown in phantom in FIG.  12 ), runners  128  and  130  of the top tray contact surface  154  of the bottom tray, runner  132  of the top tray pierces the opening  112  of the bottom tray, runner  134  pierces the opening  110  of the bottom tray, and the bottom of the apron  26  of the top tray engages the top of the apron  26   b  of the rear  14  of the bottom tray. Substantially the same engagement occurs between the second side  18  of the top tray and the first side  16  of the lower tray. 
   In a third configuration, a bottom tray and a top tray are stacked at an angle of 90° relative to one another. In the third configuration, the bottom  20  of the top tray engages the bottom surfaces  36  and  36   d  of the bottom tray.  FIG. 11  is a rear plan view of two trays stacked at an angle of 90° relative to one another. The trays can be stacked so that a bottom edge of a wall  22  of a top tray engages the fillet  24  of the front  12  of a bottom tray and a fillet  24   b  of the rear  14  of the bottom tray. The shoulder  74  and a shoulder  74   a  of the front  12  of the top tray engage the aprons  26  and  26   b  and limit the movement of the top tray relative to the bottom tray. Like shoulders can be formed in the rear  14  to engage the aprons  26  and  26   b.    
   While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.