Patent Publication Number: US-2016244263-A1

Title: Cart for moving items

Description:
This application is a divisional of U.S. patent application Ser. No. 13/294,122 filed Nov. 10, 2011, now U.S. Pat. No. 9,327,952, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     Electronic marketplaces (e.g., Internet- or web-based marketplaces) have become legitimate alternatives to traditional “brick and mortar” retail stores. For instance, consumers may visit a merchant&#39;s website to view and/or purchase goods and services offered for sale by the merchant (and/or third party merchants). In many cases, consumers appreciate the convenience and simplicity of the shopping experience provided by electronic marketplaces. For example, a consumer may quickly browse an electronic catalog (e.g., via a web browser) and select one or more items from the catalog for purchase. Such items may be shipped directly to the consumer thereby relieving the consumer of the inconvenience of traveling to a physical store. 
     Some electronic marketplaces include large electronic catalogs of items offered for sale. Distributors that operate such marketplaces may process inventory of items in one or more facilities (e.g., warehouses, distributions centers, etc.). Some product sellers have facilities in only a relatively small number of locations. Shipping from the small number to myriad domestic and foreign locations of customers requires that many items be shipped long distances. 
     In some fulfillment centers, large inventory items, such a flat screen televisions, barbeque grills, and weight sets, are moved using machines or power equipment such as fork lifts. Moving an item using machines or power equipment may in some cases cause damage to an item or its packaging. For example, a box of a flat screen television may be damaged when a fork lift is inserted under the box. 
     In some cases, damage to an item or its packaging can be avoided by manually moving the item instead of using machines. Nevertheless, for large items, such as large flat screen televisions, it may be necessary to have a team of persons lift and transport the item. Having two or more persons instead of one person involved in picking and moving an item tends to increase the labor and expense associated with fulfilling orders from inventory. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates one embodiment of cart for moving items including rollers on upper surfaces of the cart. 
         FIG. 2  illustrates one embodiment of a cart mounted on an order picker that can be used to pick and stow televisions and other bulky items from a storage rack and move the picked televisions to another location. 
         FIG. 3  illustrates an embodiment of a cart with accumulated items arranged in a row. 
         FIG. 4  illustrates an embodiment of removing an item from a cart. 
         FIG. 5  illustrates one embodiment of roller-to-roller transfer of an item onto a cart from a storage rack. 
         FIG. 6  illustrates one embodiment of roller-to-roller transfer of an item from a cart to a processing platform. 
         FIG. 7  illustrates an embodiment of a cart including retaining door panels that slide between open and closed positions. 
         FIG. 8  illustrates an embodiment of a cart including retaining bars. 
         FIG. 9  illustrates one embodiment of a cart including a floor drive system and a lift mechanism. 
         FIG. 10  illustrates one embodiment of a cart having declined upper surface rollers. 
         FIG. 11  illustrates one embodiment of a stop device for maintaining items in position on a cart. 
         FIG. 12  illustrates one embodiment of managing inventory using a cart. 
         FIG. 13  illustrates one embodiment of roller-to-roller transfer of items between a cart and a platform. 
     
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include,” “including,” and “includes” mean including, but not limited to. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Various embodiments of systems and methods for moving items are disclosed. According to one embodiment, a cart for moving items includes a base, wheels coupled to the base, and rollers coupled on an upper surface of the base. The base includes one or more loading areas for loading items to be moved onto the base and one or more unloading areas for unloading items from the base. Rollers coupled on one or more upper surfaces of the base in the loading areas may support items as the items are loaded onto the base. In some embodiments, the cart includes fork pockets coupled to the base. The fork pockets may be used with an order picker. In some embodiments, a system includes one or more tugger attachments (for example, on the front and the back of the cart). 
     According to one embodiment, a system for managing inventory of physical items includes a cart having a base having one or more loading/unloading areas for loading or unloading items to be moved. Rollers are coupled on an upper surface of the base in at least one of the loading/unloading areas. The rollers support items as the items are loaded onto the base or unloaded from the base. In some embodiments, the system includes a motorized system, such as an order picker, for moving the cart from one place to another. In certain embodiments, the system includes a walkie or automatic guided vehicle (“AGV”). The walkie or AGV may be used to move the cart from place to place. 
     According to one embodiment, a method of managing inventory includes loading items onto a loading area of a cart. During loading, the items being loaded are moved across rollers on an upper surface of the cart. The items are moved from a loading area of the cart to an unloading area of the cart. The cart is moved from a loading site to an unloading site. The items are unloaded from the unloading area of the cart. 
     According to one embodiment, a method of transferring an item between a cart and a platform includes rolling a first portion of the item on one or more cart rollers on the cart. While the first portion of the item is rolled on the cart rollers, a second portion of the item is rolled on one or more platform rollers on the platform. During at least a portion of the move between the cart and the platform, the item is supported by both the cart rollers and the platform rollers. 
     As used herein, “base” means an element or combination of elements on which other elements can be placed or mounted. A base may have any shape, including rectangular, square, ovate, circular, or irregular. A base may have any suitable construction, such as one or more plates, frames, rails, channels, platforms, grids, or combinations thereof. A base may include any number of upper surfaces on which elements can be placed or attached. In some embodiments, a base includes moving elements such as rollers mounted to one or more fixed base members. 
     As used herein, “cart” means an element or combination of elements on which items can be placed and transported from one place to another. A cart may have wheels, treads, or other elements to facilitate movement of the cart from one place to another. 
     As used herein, a “track” means an element or combination of elements that form a path over which an item can be moved. Elements that may form a track include rails, rollers, belts, or combinations thereof. A path created by a track may be linear, non-linear (for example, curved), or a combination thereof. In one embodiment, a track is formed by a series of rollers attached to a fixed base. 
     As used herein, “area” means an area, zone, or region of an item. An “area” does not require specific boundaries or dimensions. For example, a loading area may be a portion of a cart in which items can be loaded. In addition, different areas may overlap or coincide. For example, a loading area and an unloading area on a cart may be the same area or may overlap with one another. As another example, a holding area and an unloading area on a cart may be the same area or overlap with one another. 
     As used herein, “coupled to” includes a direct connection or an indirect connection. Elements may be coupled to one another in any of various manners, including a fixed connection, pivoting connection, sliding connections, or combinations thereof. 
     As used herein, “lateral” or “laterally” includes in a lateral direction or a generally horizontal direction. 
     As used herein, “shelves” or “shelving” includes any system, element, or combination thereof that has one or more shelves, platforms, or other surfaces for holding items. 
     As used herein, a “space” means a space, area or volume. 
     As used herein, “tier” means a row or level of one or more objects. A tier may be part of an arrangement or assembly of objects. Objects in one tier may be above or below items in one or more other tiers of objects within an arrangement. 
     In various embodiments, a wheeled cart is provided for moving items. The cart may have one or more loading areas for loading items and one or more unloading areas for unloading the items. Rollers are provided on the upper surface of the cart to support items as they are loaded onto the cart or unloaded from the cart. 
     A cart may be used for moving any physical item. In some embodiments, the packaging for items, or the items themselves, have a box shape. In some embodiments, the items may be relatively large and/or relatively heavy items. For example, cart may hold shipping boxes whose length is greater than 18 inches and weighs more than 50 pounds. Examples of items that may be transported on a cart include television sets, barbeque grills, unassembled furniture kits (such as bookshelves), and sports equipment (such as a basketball goal or a weight set). 
       FIG. 1  illustrates one embodiment of cart for moving items having rollers on upper surfaces of the cart. Cart  100  includes base  102 , rail system  104 , and wheels  106 . Rail system  104  is attached to base  102 . Wheels  106  may be used to roll cart  100  from place to place on a floor. In some embodiments, wheels  106  are mounted on casters. Cart  100  may be moved in any direction on a floor. 
     Cart  100  includes loading area  108  and holding area  110 . In some embodiments, items are loaded onto cart  100  in loading area  108  and items are accumulated on cart  100  in holding area  110 . In the embodiment shown in  FIG. 1 , all or part of holding area  110  may serve as an unloading area from which items can be unloaded from cart  100 . 
     Cart  100  includes loading area rollers  114  on base  102  in loading area  108 . In some embodiments, rollers  114  are ball transfer devices. Ball transfer devices may, for example, include spherical rollers that roll in any direction relative to a fixed mount secured to base  100 . In some embodiments, rollers  114  are ball transfer devices that include bearings for reducing friction between rolling elements and a fixed mount. An item placed on rollers  114  may move in any horizontal direction on rollers  114  (left to right, front to back, or any combination thereof), with rollers  114  rolling underneath the item as the item is translated horizontally relative to base  100 . 
     Cart  100  includes rollers  112  between loading area  108  and holding area  110 . Rollers  112  may roll relative to base  100 . In some embodiments, rollers  112  are cylindrical rollers. Rollers  112  may form roller track  116   a  and roller track  116   b  on either side of cart  100 . Roller track  116   a  may be parallel to, and spaced from, roller track  116   b.    
     Rollers  118  are provided at the end of roller track  116   b . Rollers  118  may roll relative to base  100 . In some embodiments, rollers  118  are ball transfer devices. Rollers  118  may be used to aid in removing items from cart  100 . 
     Although in the embodiment shown in  FIG. 1 , cart  100  includes a combination of spherical rollers and cylindrical rollers, a cart may in various embodiments include only spherical rollers or only cylindrical rollers. 
     Rail system  104  includes side rails  120  and end rail  122 . Side rails  120  may inhibit items from coming off of base  100  along the sides of cart  100 . End rail  122  may inhibit items from coming off of base  100  at the holding area-end of cart  100 . 
     Side rails  120  include unload doors  124   a  and  124   b  and loading area doors  126   a  and  126   b . Unload door  124   a  or unload door  124   b  may be opened to allow items to be removed from holding area  110 . Loading area door  126   a  or loading area door  126   b  may be opened to allow items to be introduced on the sides of cart  100  at loading area  108 . Unload doors  124   a  and  124   b  and loading area doors  126   a  and  126   b  may be attached to side rails  120  and end rail  122  by way of hinges. 
     In some embodiments, the width of base  102  between side rails is about the same as the width of the items to be held on cart  100 . 
     Cart  100  includes fork sockets  130 . Fork sockets  130  may each receive a tine of a fork of an order picker, fork lift, or other lift machine. 
     Cart  100  includes walkway  132 . Walkway  132  may provide a location for loading personnel to stand while items are being loaded, unloaded, or repositioned on cart  100 . In the embodiment shown in  FIG. 1 , walkway  132  is between two sets of roller tracks, a walkway may be located anywhere on a cart. For example, a walkway may be located to on one side of a cart between a side rail and one or more sets of roller tracks. In certain embodiments, walkway  132  may be omitted. 
     Cart  100  includes handle  134 . Handle  134  may be used by personnel to push or pull cart  100  from one location to another on wheels  106 . 
     In some embodiments, a cart with upper surface rollers is used in conjunction with a lift machine, such as an order picker.  FIG. 2  illustrates one embodiment of a cart mounted on an order picker that can be used to pick televisions and other bulky items from a storage rack and move the picked televisions to another location. 
     System  140  includes storage rack  142 . Storage rack  142  holds television boxes  144 . Storage rack  142  includes levels  146   a ,  146   b , and  146   c.    
     System  140  includes cart  100  mounted on order picker  148 . Order picker  148  includes column  150 , platform  152 , control panel  154 , and drive system  156 . The height of platform  152  may be adjustable, for example, so that platform  152  may be raised and lowered to any of levels  146   a ,  146   b , or  146   c . In one embodiment, cart  100  is mounted on a fork extending from platform  152 . Control panel  154  may be operated from platform  152  to raise or lower platform  152 , to move order picker  148  from one location to another on the floor of the facility, or both. Outriggers  158  may counteract cantilevered loads of cart  100  on order picker  148  and provide stability to order picker  148 . 
     To load television boxes  144  onto cart  100 , door  126   a  may be placed in an open position. Box  144  may be pulled from storage rack  144  onto loading area rollers  114  in loading area  108  of cart  100 . Loading area rollers  114  may roll as box  144  is translated away from storage rack  144  and across the width of cart  100 . Box  144  may continue to be pulled away from storage rack  142  until box  144  is entirely on cart  100 . Door  126   b  may inhibit box  144  from being inadvertently pulled off the back side of cart  100 . 
     In some embodiments, a storage rack levels are selected based on the height of the items to be stowed. For example, the spacing between tiers in a storage rack may be sized to match the height of television boxes  144  (for example, to maximize utilization of storage space). In certain embodiments, different sections of a storage rack may be sized for different items to be stored. In certain embodiments, dimensions of a cart may be chosen to correspond with surfaces on a storage rack. For example, a cart may be sized such that the upper surface of the cart is at the same level as a shelf of the storage rack. 
     Once box  144  is entirely on cart  100 , box  144  may be pushed toward holding end  110  of cart  100 . Box  144  may travel over rollers  112  of roller tracks  116 A and  116 B. Rollers  112  may facilitate transfer of box  144  across base  100 . An operator may exit lift platform  152  and step onto walkway  132  to improve toe operator&#39;s position for pushing box  144  to a desired location on base  100 . The operator may move from location to location on storage rack  142  and load additional boxes  144  onto cart  100 . Boxes  144  may be accumulated on base  102  in a horizontal row. 
       FIG. 3  illustrates an embodiment of a cart with accumulated items arranged in a row. Television boxes  144  are positioned in a row in loading area  108 . The leftmost television box  144  may contact end rail  122 . In  FIG. 3 , doors  124   a  and  124   b  are shown as partially swung open for illustrative purposes. As indicated by the arrows, television boxes  144  may be removed from cart  100  in either direction. 
       FIG. 4  illustrates an embodiment of removing an item from a cart. Box  144   a  may be removed from cart  100 . As box  144   a  is moved across base  102  and through open doors  124   b , rollers  118  may roll relative to base  102 . Rollers  118  may facilitate removal of box  144   a  from cart  100 . 
     In some embodiments, an item is moved to or from a cart by roller-to-roller transfer. In one embodiment, a cart is positioned so that rollers on the cart are co-planar with rollers on a platform from which an item is to be loaded. 
       FIG. 5  illustrates one embodiment of roller-to-roller transfer of items onto a cart from a storage rack. System  160  includes storage rack  162 , cart  100 . Storage rack  162  includes shelf  164 . Shelf  164  includes roller assemblies  166 . Roller assemblies  166  include rods  167  and rollers  168 . Cart  100  may be raised to the level of shelf  164 , for example, by a lifting apparatus such as an order picker (the lifting apparatus is omitted for clarity). As one of television boxes  144  is moved from shelf  164  to cart  100 , the leading portion of the television box may move across rollers  114  in loading area  108  of cart  100 . At the same time, the trailing portion of the television box may move across rollers  168  on shelf  164 . In some embodiment, only one person may be involved in moving the box from storage rack  162  to cart  100 . 
     In some embodiments, a cart is positioned so that rollers on the cart are co-planar with rollers on a platform from to which an item is to be unloaded.  FIG. 6  illustrates one embodiment of roller-to-roller transfer of items from a cart to a platform. Processing platform  180  includes roller assemblies  182 . Roller assemblies  182  include rods  183  and rollers  184 . Cart  100  may be placed into position relative to processing platform  180  such that rollers  118  are at the same level as rollers  184 . As one of television boxes  144  is moved from cart  100  to processing platform  180 , the leading portion of the television box may move across rollers  184  of processing platform. At the same time, the trailing portion of the television box may move across rollers  118  on cart  100 . In some embodiments, only one person may be involved in moving the box from cart  100  to processing platform  180 . 
     Although in the embodiment shown in  FIG. 1 , cart  100  includes retaining elements in the form of rails, a cart may in various embodiments have other types of retaining elements or structures. Examples of other retaining elements include walls, panels, screens, vertical posts, cables, rods, or bars, and combinations thereof. 
     In some embodiments, retaining elements of a cart may be opened and closed without going extending or enlarging the footprint of the cart.  FIG. 7  illustrates an embodiment of a cart including retaining door panels that slide between open and closed positions. Cart  200  includes base  102 , side rail  202 , unload doorpost  204 , and load door post  206 . Unload area door  208  and load area door  210  are mounted on side rail  202 . Each of unload area door  208  and load area door  210  can slide between an open position and a closed position on side rail  202 . For example, unload area door  208  can be slid from a closed condition against unload door post  204  and an open position represented by the phantom lines. 
     In various embodiments, retaining elements include devices for securing retaining elements in position. For example, as shown in  FIG. 7 , unload area door  208  includes latch  212  and load area door  210  includes latch  214 . Latch  212  may couple to unload door post  204 . Latch  214  may couple to load door post  206 . 
     Although for illustrative purposes only one side of cart  200  is shown in  FIG. 7 , both sides of cart  200  may have a sliding door arrangement similar to that shown in  FIG. 7 . 
       FIG. 8  illustrates an embodiment of a cart including retaining bars. Cart  220  includes base  102 , side rail  222 , unload end post  224 , and load end post  226 . Chain  227  may be attached to unload end post  224  and side rail  222 . Chain  229  may be attached to load end post  226  and side rail  222 . Retaining bars  228  may be pinned to side rails  222  and unload end post  224 . Retaining bar  230  may be pinned to side rail  222 . Retaining bars  228  and  230  may be swung upwardly, and chains  227  and  229  may be detached as needed to allow items to be loaded or unloaded on the sides of cart  220 . 
     Although for illustrative purposes only one side of cart  220  is shown in  FIG. 8 , both sides of cart  220  may have a retaining bar arrangement similar to that shown in  FIG. 8 . 
     In some embodiments, a cart includes a lift system, a tractor system, or both.  FIG. 9  illustrates one embodiment of a cart including a floor drive system and a lift mechanism. System  240  includes base  102 , rail system  104 , lift system  242 , and floor drive system  244 . Lift system  242  includes lift drive mechanism  246  and scissor assembly  248 . Lift drive mechanism  246  may be operated to extend and compress scissor assembly  248 . Lift system  242  may be operated to raise and lower the level of base  102 . Floor drive system  244  may be operated to move cart  240  from one location to another. In some embodiments, lift system  242  and floor drive system  244  are controlled by a computer control unit. In certain embodiments, an operator may control lift system  242  and floor drive system  244  while standing on base  102 . 
     In some embodiments, rolling surfaces of a cart may be at a decline.  FIG. 10  illustrates one embodiment of a cart having declined upper surface rollers. Cart  260  includes base  262 , rail system  264 , and rollers  266 . Rollers  266  may be angle  268  relative to horizontal. As items are loaded onto the higher side of cart  260 , gravity may assist an operator in moving items from higher end  270  of cart  260  to lower end  272  of cart  260 . In certain embodiments, rollers  266  may be powered rollers (for example, motorized). Power rollers may be used in moving items from one area to another on the cart. In some embodiments, power rollers are used to raise items to the higher end of a cart. 
     In some embodiments, a cart includes one or more stop members. The stop members may keep items in place on the cart or at rest on the cart. For example, a stop member may be positioned to inhibit one or more items in a stack of items from tipping over or shifting from one location to another on the cart. In some embodiments, a stop device may be adjustable, for example, to allow the stop to be moved into position against an item to be held.  FIG. 11  illustrates one embodiment of a stop device for maintaining items in position on a cart. Cart  280  includes base  282 , walkway  284 , roller tracks  285 , stop rails  287 , and stop device  288 . Stop device  288  includes stop bar  290 . Stop device  288  may be mounted on stop rails  287 . The stop device  288  may be adjusted by sliding stop bar  290  on stop rails  287 . Stop device  288  may be selectively retractable or rotatable to a position below the level of rollers  285  so that stop bar does not interfere with transfer of boxes from the loading area to the holding area of cart  280 . During movement of cart  280 , stop bar  290  may be deployed against the foremost box  144  on cart  280 . Stop bar  290  may inhibit all of boxes  144  from shifting forward or from tipping over in cart  280 . 
     Although in  FIG. 11 , a stop device is shown for illustrative purposes as a bar that slides on rails adjacent to the walkway, a stop member may have various other forms and mounting arrangements. In certain embodiments, a stop member is coupled to a side rail or end rail of a cart such that it can be slid along the rail. The stop bar can be moved (for example, flipped down into the space between the rails) into a position diagonally across a box to hold boxes in place on a cart. 
     In some embodiments, items are transported from one placed to another on a cart that has rollers on the upper surface of the cart in a loading area. The items may be moved out of the loading area into an unloading area on the cart. After moving the cart from a loading site to an unloading site, the items can be removed from the unloading area. 
       FIG. 12  illustrates one embodiment of managing inventory using a cart. At  300 , a cart is positioned for loading of an item. In some embodiments, the cart may be mounted on truck and raised to a position where the platform of the cart is co-planar with a surface where the item to be moved is resting, such a warehouse shelf. Doors of the cart may be placed in appropriate positions for the load. For example, a opposite door may be closed to inhibit an item from coming off the cart on the far side of the cart. For example, loading area door  126   b  opposite storage rack  142  may be placed into a closed position, such as shown in  FIG. 2 . 
     At  302 , an item is loaded onto a loading area of a cart. As the item is moved onto the cart, the item may be moved across one or more rollers on the cart. In some embodiments, the rollers on the cart are ball transfer devices. 
     At  304 , the item is moved from a loading area of the cart to a holding area of the cart. In some embodiments, the item is moved across rollers as the item is shifted from the loading area to the holding area. In certain embodiments, items are loaded onto the cart in one direction and items are accumulated by moving the items in a different direction than the direction of loading. For example, as shown in  FIG. 2 , an item may be moved onto a cart from one side of the cart, the moved lengthwise with respect to the cart from one end of a cart to the other end. 
     After each item is loaded, the cart is moved to the next pickup location. In some embodiments, the cart is moved by controlling a drive system, such a drive system on an order picker or fork lift. The cart may be moved from location to location to pick up successive items, and each item loaded onto the cart. In some embodiments, one person transfers the items onto the cart. In other embodiments, a team of two or more persons loads items onto the cart. 
     In some embodiments, a loader/operator alternately moves between a cart walkway during item picking. For example, the loader may stand on the order picker control platform to move the cart into position for each item, and then step onto the walkway to load each item. 
     After each item is loaded onto the cart, the item may be shifted from the loading area on the cart to a holding area in the cart. In some embodiments, items are accumulated in one or more rows of items in a horizontal “stacking” arrangement. In certain embodiments, items are accumulated in two or more columns of items (for example, one column of items on each roller track shown in  FIG. 1 ). In some embodiments, a stop device adjusted and deployed after each item is loaded to inhibit movement of the items as the cart is moved from location to location. 
     Once all of the items have been loaded onto the cart, the cart may be moved to an unloading site at  306 . Any doors or other retaining members can be opened to allow unloading of items from the cart. At  308 , items are unloaded from the cart. The unloading site may be, for example, an outbound area of a fulfillment center. Unloading destinations may include, for example, a floor, a platform, a pallet, a truck, a shipping container, or a conveyor belt. In some embodiments, the item is pushed across rollers on the cart as the item is moved off of the cart. 
     In some embodiments, items are loaded onto a cart, or unloaded from a cart, by way of a roller-to-roller transfer.  FIG. 13  illustrates one embodiment of roller-to-roller transfer of items between a cart and a platform. At  320 , a first portion of an item is rolled on cart rollers on the cart. The item may be engaged on the cart rollers either during loading of the item onto the cart or during unloading of the item from the cart onto the platform. While the item is rolled on the cart rollers, a second portion of the item may be rolled on platform rollers on the platform at  322 . At  324 , the item is moved between the cart and the platform. During at least a portion of the move, the item may be partially supported on the cart rollers and partially supported on the platform rollers. In some embodiments, the item is translated across the surfaces of the cart and platform such that the item is moved without lifting the item from either the platform or the cart. 
     In various embodiments shown and described above, a cart has rollers for assisting in shifting items from a loading area to a holding area of a cart. A cart may, however, include in certain embodiments include other mechanisms for shifting items from one area to a cart to another. For example, a cart may include a conveyor belt mechanism for shifting items from one place to another on a cart. In certain embodiments, a powered mechanism is used to assist in loading items onto a cart, unloading items from a cart, or shifting items from one position to another on a cart. 
     Although the embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.