Abstract:
A molded plastic pallet, connects opposing sides of the pallet bottom, has a cross rail that has a crowned surface. Thus, should the wheels of a pallet jack rest on the surface of the rail as the jack&#39;s fork prongs are inserted under the pallet, they will be urged to roll off the rail, to avoid damage to the pallet which could occur when the jack lifts the pallet.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims benefit of U.S. Provisional Patent Application No. 60/655,792, filed Feb. 23, 2005 and is a continuation-in part of U.S. patent application Ser. No. 10/729,615, filed Dec. 5, 2003, which is a divisional of U.S. patent application Ser. No. 09/938,954, filed Aug. 24, 2001, now U.S. Pat. No. 6,705,237, which claimed priority to U.S. Provisional Patent Application Ser. No. 60/227,537, filed Aug. 24, 2000, the entire contents of each of which are specifically incorporated herein by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     This disclosure relates to a device for the transportation of packaged goods, and, more particularly, to a pallet that meets certain standards set by the Grocery Manufacturers Association (GMA) and others for weight, durability, and strength.  
       BACKGROUND  
       [0003]     The present disclosure relates to improvement in pallet cross rails, and in some embodiments to an improvement useful on the pallet invention described in U.S. Pat. No. 6,705,237 and any other pallet having analogous features referred to below. In a pallet made in accord with the aformentioned patent, metal beams are embedded in the thermoplastic base of the pallet, which lie along the path of a rectangle neat the outer edges of the pallet. There are other metal beams at the base elevation, which act as rails, connecting opposing sides of the base and intersecting at the center of the pallet. They lie along the plane of the surface upon which a pallet typically rests during use for carrying goods; and they provide strength to the pallet.  
         [0004]     One of the problems relating to any pallets, and shared by plastic pallets, relates to the use of hydraulically powered pallet jacks, also called pallet hand trucks, referred to here simply as jacks. Typically, jacks are wheeled, manually powered devices which lift a pallet an inch or more off the ground, so that the pallet can be transported a short distance by pulling the jack by its handle, by rolling the jack with pallet along a warehouse floor or the like. A typical jack has two spaced-apart fork prongs which raise and lower vertically, usually under action of a manual hydraulic pump, when the fork prongs are positioned under the pallet. See U.S. Pat. No. 3,982,767 for a fuller description of a jack. In use, the jack is positioned beneath a pallet, essentially by inserting the jack fork prongs into the side openings of a pallet, where forks of a powered fork lift otherwise enter. The typical jack has a wheeled carriage, relative to which the fork prongs move up and down. The carriage has wheels in vicinity of the outer ends of the fork prongs. Thus, to insert the fork prongs under the pallet, when the jack is in its collapsed or minimum height position, the wheels must pass over the any rail which connects the opposing edges of the pallet.  
         [0005]     In wooden pallets, the edges of such rails are often beveled to make easier the motion of the wheels as they “bump” over the rail. Even so, a certain amount of rough force is usually employed by the jack operator to position the jack. With a conventionally dimensioned pallet, when a jack is fully inserted, the end wall of the jack contacts the near-edge of the pallet, and the outer-end wheels of the carriage are appropriately positioned, so they rest on the floor between any center rail and the far-edge rail. Thus, when the operator lifts the fork prongs, they lift the pallet and it is supported by the outer end wheels and the inner end wheels of the jack carriage, which are outward from the near-edge of the pallet.  
         [0006]     It is a problem that, when jack operators are uncaring or there is some difficult access situations, the jack may be only partially inserted, and one or both wheels can rest on a rail. When the fork prongs are then lifted, there is force between the rail and the upper deck of the pallet, and the pallet can be pushed apart and in fact destroyed. Because plastic pallets can cost substantially more than wood pallets, such errors become more economically consequential, and thus it is an aim to prevent the bad event.  
       SUMMARY  
       [0007]     The above described and other problems and disadvantages of the prior art are overcome and alleviated by the present pallet having one or more rails, which rails run along the floor and connect opposite sides of the pallet, wherein one or more cross rails have a top surface that is crowned. In such embodiments, if the wheels at the outer end of a pallet jack are improperly positioned so that they rest on the cross rail, they are urged by the crown shape and gravity to roll off the cross rail. In alternate exemplary embodiments, the crowned surface may be a curve with the apex at the center of the cross rail, or the crowned surface may comprise one or more sloped planar surfaces.  
         [0008]     The foregoing and other objects, features and advantages of the present pallet will become more apparent from the following description of exemplary embodiments and accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     Referring now to the accompanying FIGURES, which are meant to be exemplary and not limiting:  
         [0010]      FIG. 1  is a partial cross sectional side view of a pallet including exemplary crowned cross rails;  
         [0011]      FIG. 2  is a top elevation view of an exemplary pallet including cross rails positioned for insertion of a jack;  
         [0012]      FIG. 3  is a cross section side view of an exemplary crowned cross rail having angled top surfaces; and  
         [0013]      FIG. 4  is a cross section side view of an exemplary crowned cross rail having beveled bottom surfaces.  
     
    
     DETAILED DESCRIPTION  
       [0014]     As described above, the present disclosure relates to pallets having crowned interior cross rails, which rails run along the floor and connect opposite sides of the pallet. The rails run transverse to the length direction of the fork prongs of a fork jack inserted under the pallet for transport.  
         [0015]     Referring now to  FIGS. 1 and 2 , an exemplary pallet  20  is illustrated proximate to a hand jack  30 .  FIG. 1  illustrates a vertical partial cross section of pallet  20 .  FIG. 2  illustrates the pallet in top view. In both illustrations, the jack is ready to enter the space within the pallet, through the side opening thereof. Pallet  20  has an upper deck  28 , a base  29  and connecting columns  22 A,  22 B,  22 C,  22 D. The bottoms of the columns are connected by outer rails  33  which provide the periphery of the base. The center points of the bottom edges are connected by cross rails  34 . In one exemplary embodiment, the rails  33  are molded plastic and have a metal reinforcing beam  36 , in accord with the description in U.S. Pat. No. 6,705,237. However, it should be noted that the present crowned cross rail configuration is applicable to any pallet having cross rails.  
         [0016]     Referring still to  FIGS. 1 and 2 , to use a hand jack  30 , the operator rolls the leading end of the jack into the interior of the pallet, so the length of the fork prongs  42  underlies the pallet deck  28 . The path of the outer-end wheels  32  of the carriage  44  of the jack is shown by the dashed arrow line in the Figures. When the operator feels that the jack is in position, the operator makes the jack expand in height, wherein the fork prongs  42  rise relative to the carriage  44 . Typically that is accomplished by a toggle or scissors mechanism that actuates a hydraulic cylinder. The pressurized fluid for the cylinder is provided a hand pump worked by the operator. However, as pointed out above, if the wheels  32  of the jack happen to rest on one of the rails  34 , then the pallet can be torn apart. The problem is that operators may not realize that the wheels  32  rest on one of the rails  34 .  
         [0017]     Referring now to  FIG. 1 , an exemplary cross rail is illustrated. In one embodiment, the interior of cross rails  34 , which in one embodiment may be molded thermoplastic, have a hollow metal beam  36  with rectangular cross section. The top surface of the molded plastic rail has a crown, such as the curved surface, with the apex nominally at the center of the width of the cross rail, shown in  FIG. 1 . Thus, if the wheels of the jack carriage are positioned to rest on the top of the rail, the crowned contour of the rail surface, abetted by gravity, will tend to cause the wheels and carriage to be thrust in one direction or the other. That will tend to cause the jack to move further into the pallet, or to move outwardly, so the wheels will rest on the floor surface adjacent the rail, rather than on the rail, thus avoiding the problem of tearing the pallet apart.  
         [0018]     Referring still to  FIG. 1 , while the illustrated top surface of the rail  34  is curved, other exemplary top surface contours are contemplated (and should be included in the definition of “crowned”), as long as such contours promote movement of jack wheels off of the rail top surfaces.  
         [0019]     Referring now to  FIG. 3 , a crowned top surface of the rail  34 A comprises at least one sloped surface  35 . While the illustrated crowned top surface comprises opposing oblique planar surfaces, a greater number than the two sloped and intersecting planar surfaces  46  of  FIG. 3  may be used to form the crown. Alternately, a single inclined plane may be used as the top surface of a rail.  
         [0020]     A rail in accordance with those disclosed herein may have vertical edges  48 , as shown in  FIG. 3 . In one exemplary embodiment, an outer rail is not crowned and an inner rail is crowned (See rails  34 R and  34  in  FIG. 1 ) (though this should not be construed to imply that the outer rail cannot be crowned). It tends to be less of a problem that an operator may let the wheels rest on the outer rails  34 . As such, the outer rails may be squared or may be only provided with beveled edges. In another exemplary embodiment, the height of the vertical edges  48  of the crowned rail  34  are about the same as the height of the outer rail  34 R.  
         [0021]     Referring now to  FIG. 4 , a crowned rail  34 B includes a sloped top surface  37  and a recessed lower surface  38 . This recessed lower surface  38  may be angled or curved inward to any degree and for any convenient height. The recessed lower surface  38  advantageously facilitates insertion of the forks of a fork truck between the bottom of the floor  39  or other surface and underneath the cross rail  34 B. In another exemplary embodiment, an uncrowned cross rail includes a recessed lower surface.  
         [0022]     With regard to any of the embodiments, any amount of rise of a crowned surface, or height of a center apex of the crowned surface, of a rail is contemplated, as long as the height is not such that the carriage or fork prongs would hit the underside of the top deck or portions of the frame.  
         [0023]     While the crowned cross rails are especially useful for plastic pallets (due to the cost, moldability, reinforceablity, etc. of plastic constructions), it may of course also be applied to pallets made of other materials, including wood pallets. Without being limiting, a pallet having a plastic construction may be made of polyethylene, polypropylene or other thermoplastic in alternative ways and with alternative configurations.  
         [0024]     Although this invention has been shown and described with respect to a exemplary embodiments, it will be understood by those skilled in this art that various changes in form and detail thereof may be made without departing from the spirit and scope of the claimed invention.