BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a device that may be received within a typical square hitch receiver found on a vehicle, wherein the device holds articles for transport and, wherein the device may hold articles and transport articles when utilized as a hand cart (it may be used independently as a manually operated cart without being inserted into a typical hitch receiver found on a vehicle) and, wherein the device may hold articles and transport articles when utilized as a trailer. 
     2. Background of the Prior Art 
     Current devices that are designed to be used as receiver hitch cargo carriers for transporting loads or articles are generally intended for a singular method of managing the load. A typical vehicle receiver hitch cargo carrier is stored in the garage until it is needed on rare occasions to transport loads that do not fit within a vehicle&#39;s compartments. Attempts to expand the limitations of the typical cargo carriers by transforming the cargo carriers to enable it to perform dual purposes such as a wheeled dolly or a wagon are evident in some examples of prior art. While some examples of prior art are more effective and versatile than the typical cargo carrier, such examples are not without their limitations. The individual who uses a receiver hitch cargo carrier in the capacity of a wheeled dolly or cart will typically need other devices to manage a variety of load and article transporting objectives. There is a need for a system that enables a single device to be adapted in order to meet a wide range of cargo and/or article handling, storage, and transportation objectives that are not limited to but include: a vehicle receiver hitch cargo carrier, a pickup truck bed extender, a vehicle receiver hitch bicycle carrier, a tailgate grill, a beach or pier fishing cart, a game (hunting) cart, a yard-work cart, a bicycle trailer, and other user defined necessities. 
     This invention expands the usefulness of receiver hitch cargo carriers and manually transported carts by providing a convertible cargo carrier and cart system that affords the ability to add vertical receivers and inserts to the platform of the cargo carrier and allow the user to adapt the convertible cargo carrier and cart system in order to provide a better means of managing a variety of cargo handling, cargo storage, and cargo transporting objectives. While utilizing the convertible cargo carrier and cart system in the capacity of a receiver hitch cargo carrier vertical inserts can be inserted in the cargo carrier wherein the vertical inserts can be adapted to support articles while transporting articles. The vertical inserts can also be used to define and contain the length and width of a load while also providing a means to secure articles thereby offering improved methods to manage the cargo or article handling objectives. The vertical inserts can further be used while the vehicle is in a stationary position to support articles such as a tailgate grill or other devices. 
     A handle accessory can be stowed inside the cargo carrier&#39;s framework wherein the handle reinforces the strength of the cargo carrier&#39;s receiver tube when it is in the stowed position. A leg/foot accessory can also be stowed within the cargo carrier&#39;s framework without impacting the area that is designated for the load, wherein a tongue component of the handle accessory is designed to secure the leg/foot accessory in the stowed position while utilizing the convertible cargo carrier and cart system in the capacity of a receiver hitch cargo carrier. 
     The cargo carrier, vertical inserts, and accessories can be easily removed from a vehicle&#39;s receiver hitch wherein the convertible cargo carrier and cart system is easily converted to a manually controlled cart for a wide variety of applications. 
     SUMMARY OF THE INVENTION 
     The convertible cargo carrier and cart system holder of the present invention addresses the aforementioned needs in the art by providing a cargo carrier wherein accessories can be attached to and stored within the cargo carrier&#39;s framework and platform and article supports can be added to the perimeter sides of the cargo carrier&#39;s platform. A handle accessory, appropriate hardware, and article supports can be used for managing and transporting loads when using the cargo carrier as a manually operated cart. The device can also be secured to the trailer hitch of a vehicle wherein the user can select appropriate accessories to manage and transport articles or loads via a motorized vehicle. Additionally, the cargo carrier can be easily converted to a bicycle trailer wherein the handle accessory can be used to secure the cargo carrier to a bicycle receiver (not shown) wherein the user can select appropriate accessories to manage and transport articles or loads via a bicycle. 
     The convertible cargo carrier and cart system is of relatively simple design and construction, being produced using standard manufacturing techniques, so as to be relatively inexpensive to produce so as to be economically attractive to potential consumers of this type of device. 
     The convertible cargo carrier and cart system of the present invention is comprised of a horizontal receiver tube that is affixed to a generally rectangular shaped platform wherein the platform has a top (upper) side and a bottom (under) side and four perimeter sides. The platform having rows of rectangular shaped vertical receivers on the perimeter sides and the platform also having framework receivers built within the underside of the platform. 
     The user can utilize common hardware to attach preferred wheels to vertical inserts and then install the vertical insert and wheel assembly into selected vertical receivers that are most suitable for managing the load. The handle assembly can be moved within the cargo carrier&#39;s receiver tube from a stowed position to a position that allows the pivot-able assembly of the handle to be rotated to a vertical position which allows the user to control the cart while in a standing or walking position. The leg/foot accessory can also be pivoted to a vertical position to support the cargo carrier in a rest position. 
     The convertible cargo carrier and cart system is designed in such a manner that encourages the development of accessories that further expand the usefulness of the system by addressing the needs of additional applications without departing from the spirit and scope of the present invention. One such example of expanding the usefulness of the convertible cargo carrier and cart system is the design of the fishing rod holders that are part of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an environmental view of the convertible cargo carrier and cart system of the present invention employed as cargo carrier for transporting articles with vertical inserts and a bicycle secured thereto. 
         FIG. 2  is an environmental view of the convertible cargo carrier and cart system of the present invention with vertical inserts and a grill secured thereto. 
         FIG. 3  is an environmental view of the convertible cargo carrier and cart system of the present invention employed as a bicycle trailer. 
         FIG. 4  is an environmental view of the convertible cargo carrier and cart system of the present invention employed as a fishing cart with fishing rod holders secured thereto. 
         FIG. 5  is a perspective view of the fishing rod holders of the present invention. 
         FIG. 6  is an environmental view of the convertible cargo carrier and cart system of the present invention employed as a hunting cart with game thereto. 
         FIG. 7  is an environmental view of the convertible cargo carrier and cart system of the present invention employed as a cart for hauling branches and yard debris. 
         FIG. 8  is a perspective view of the top side of the cargo carrier of the present invention. 
         FIG. 9  is a perspective view from the right side of the cargo carrier of the present invention. 
         FIG. 10  is a perspective view of the leg/foot accessory of the present invention. 
         FIG. 11  is a perspective view of the leg/foot accessory and the underside-view of the cargo carrier of the present invention. 
         FIG. 12  is a perspective view of the leg/foot accessory installed on the cargo carrier of the present invention. 
         FIG. 13  is a perspective view from the top of the cargo carrier of the present invention with the leg/foot accessory installed. 
         FIG. 14  is a perspective view of the handle accessory&#39;s pivot-able assembly&#39;s motion of the present invention. 
         FIG. 15  is a perspective view of the handle accessory inserted into the cargo carrier of the present invention. 
         FIG. 16  is a perspective view of the vertical inserts of the present invention illustrating a variety of hardware and wheel configurations. 
     
    
    
     Similar reference numerals refer to similar parts throughout the several views of the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, it is seen that the convertible cargo carrier and cart of the present invention, generally denoted by reference numeral  100  is comprised of a horizontal-receiver component  1 , a platform  2 , frame work receivers  3 , and vertical receivers  4 . The convertible cargo carrier and cart  100  can be used to transport articles as a hand cart with wheel assemblies W. The convertible cargo carrier and cart  100  may also be used to transport articles via a vehicle V receiver hitch cargo carrier when the convertible cargo carrier and cart  100  is inserted into a vehicle receiver hitch. 
     The platform  2  is comprised of a plurality of channel stock components  20 , each channel component having an upper side  21  and an under side  22 , a front surface  23  and a rear surface  24 . The platform  2  also having a front side  30 , a rear-side  31 , a left-side  32  and right-side  33 . The four sides ( 30 ,  31 ,  32  and  33 ) of the platform  2  are comprised of flat-bar stock. Each side ( 30 ,  31 ,  32  and  33 ) of the platform  2  has a plurality of vertical receiver securement holes  34 . Securement nuts  35  may be aligned with vertical receiver securement holes  34  and securement nuts  35  may be bonded, welded, or molded to the inner sides of the four sides ( 30 ,  31 ,  32  and  33 ) on the underside of the platform  2 . 
     The front surface  23  top edge of channel component  38  is bonded to the top edge of the platform&#39;s front flat-bar stock component  30  at the top edge of  30 . The rear surface  24  top edge of channel component  40  is bonded to the platform&#39;s rear flat-bar stock component  31  at the top edge of  31 . 
     The front surface  23  underside  22  edge and the rear surface  24  underside edge  22  of channel component  38  are bonded to the upper surface  12  of the horizontal-receiver component  1 . The front surface  23  under side  22  edge of channel component  40  is bonded to the upper surface  12  of the horizontal-receiver component  1  at the second end  11  of the horizontal-receiver component  1 . A void space is established between the second end  11  of the horizontal-receiver component  1  and the rear-side  31  of the platform  2 . The void space is approximately equal to the width of channel component  40 . This void provides stowage space for the foot section of the leg assembly in the underside of the convertible cargo carrier and cart  100 . 
     The bottom edge of front surface  23  has a cut-out that is approximately two inches by two inches at the mid-point of the front surface  23  which allows the front surface  23  to fit over the upper surface  12  of the horizontal-receiver component  1 , thus the height of the convertible cargo carrier and cart  100  is the combined height of the horizontal-receiver component  1  and platform  2 . 
     Framework receivers  3  are comprised of flat-bar stock material. One piece of flat-bar stock material is used to construct a first side  42  of a framework-receiver and a second piece of flat-bar stock material is used to construct a second side  44  of a framework-receiver. The first side  42  and the second side  44  are each equal in length to the inside width of the under-side  22  of channel stock components  20 . The first side  42  is separated from the second side  44  by a distance that is approximately 0.0125 inches wider than the square tube stock extension member  54  of the leg unit  52  which is used to construct the leg/foot accessory  50 . An accessory-support securement hole  43  passes through the framework receivers from the first side  42  to the second side  44 . Securement nuts  35  may be affixed to either the first side  42  or the second side  44  of the framework-receiver. 
     Vertical receivers  4  are comprised of a rectangular tube stock. The length of the rectangular tube stock used for each vertical-receiver  4  is equal to the height of the platform  2 . Two adjacent vertical receivers  4  share a common divider  70 . Adjacent vertical receivers  4  are bonded, welded, or molded at each common divider  70 . Each vertical-receiver  4  has a platform-side  73  that is adjacent to the platform  2  and also an opposing side  74 . A securement opening  71  is located on platform-side  73  and a corresponding securement opening  71  is located on the opposing side  74  of each vertical-receiver  4 . Securement openings  71  align with vertical receiver securement holes  34  on the platform  2 . A plurality of vertical receivers  4  forms a vertical receivers row  80 . A row of vertical receivers  80  may be affixed to one or more perimeter sides of the platform  2 . A user P can pass common hardware (eyebolts shown)  36  through each vertical-receiver  4  and also through the platform  2  to secure the vertical-receiver(s)  4  to the platform  2 . Common hardware  36  may also be used to secure vertical inserts  61  to the convertible cargo carrier and cart  100 . 
     Vertical inserts  61  are comprised of channel stock material, rectangular stock tubing, or square stock tubing. User P can select a securement hole  68  and insert appropriate common hardware to attach wheels  67  to a vertical insert as demonstrated with a spindle-bolt  65 , flat washer&#39;s  64 , spacers  66 , and cotter pins or locking nuts  63 . The vertical insert and wheel assembly W can be inserted to a selected height and the convertible cargo carrier and cart  100  may be used to transport articles or user goods as necessary. User P can select other appropriate hardware as demonstrated with J-bolts  62 , flat washers  64 , spacers  66 , and locking nuts  63  to support and transport articles as necessary. The convertible cargo carrier and cart  100  becomes a beach fishing cart when fishing rod holders  110  and appropriate beach wheel assemblies W are inserted into vertical receivers  4 . 
     A leg/foot accessory  50  is constructed using square tube stock. The leg/foot accessory  50  is comprised of leg members  52 , extension members  54  and a foot member  56 . Each leg member  52  has a foot-end  53  and a top-end  54 . The foot-end  53  of each leg member  52  is affixed to the foot member  56  equidistant from the center of the foot member  56 . Extension members  54  are attached to the top-end  55  of the leg members  52  at a right angle to the rear-side  58  of leg member  52 . 
     Each extension member  54  of the leg/foot accessory  50  has a hole  59  passing through the extension member  54  from the left-side to the right-side of the leg member  52  providing a means to pass a bolt  37  through a framework-receiver  3  and also through the leg/foot accessory  50  in order to attach the leg/foot accessory  50  to underside  22  of a channel component  20  of the platform  2 . The leg/foot accessory  50  can be pivoted to a vertical position to support the convertible cargo carrier and cart  100  or it can be pivoted horizontally and stowed within the underside of the platform  2  of the convertible cargo carrier and cart  100 . 
     A handle assembly  81  is comprised of a strength member  82 ; a pivot-able member  92 ; and a tongue component  84 . The strength-member  82  having a top-side  85 , a bottom-side  86 , a right-side  87  and an opposing a left-side, a front-end  89  and an opposing rear-end  90 . A plurality of flat-bar spacer-members  98  are affixed to the strength member  82  on each side of the strength member  82 . The spacer-members  98  create a snug fit between the outer dimension of the strength member  82  and the inner dimension of the horizontal-receiver component  1  of the convertible cargo carrier and cart  100 . The strength member  82  has a pivot-hole  88  that has a slightly larger diameter than the diameter of the pivot-pin  97  comprised of round stock material. 
     The pivot-pin  97  is passed through the pivot-hole  88  of the strength member  82 . The pivot-pin  97  extends approximately 0.125 inches beyond the right-side  87  of the handle assembly&#39;s strength member  82  and also extends approximately 0.125 inches beyond the left-side (not shown) strength member  82 . 
     The pivot-able member  92  of the handle assembly  81  is comprised of a right flat-bar component  91 , a left flat-bar component  93 , and flat-bar spacer-members  96 . The right flat-bar component  91  of pivot-able member  92  and the left flat-bar component  93  of the pivot-able member  92  each have a pivot-pin hole  94  that is equal in diameter to the diameter of the pivot-pin  97 . The pivot-pin hole  94  on the right flat-bar component  91  is pressed tightly into the pivot-pin hole  94  and the pivot-pin hole  94  on the left flat-bar component  93  is pressed tightly onto the pivot-pin  97  in parallel position to right flat-bar component  91  and also in parallel position to the strength member  82 . Flat-bar spacer-members  96  are affixed to the top side of pivot-able member  92  in such size and manner that when the pivot-able member  92  is pivoted to a stowed position against the top-side  85  of the handle assembly&#39;s strength member  82  the user P can then insert the handle assembly  81  into the horizontal-receiver component  1  of the convertible cargo carrier and cart  100 . 
     A handle assembly receiver hitch-pin hole  83  passes through the handle assembly  81 , through the right flat-bar component  91  of pivot-able member  92 , the strength member  82 , and also through the left flat-bar component  93  of the pivot-able member  92 . A handle assembly receiver hitch pinhole  83  aligns with the receiver hitch pinhole  14  of the horizontal-receiver component  1  of the cargo carrier convertible cargo carrier and cart  100 . 
     A handle pinhole  95  also passes through the handle assembly  81 , through the right flat-bar component  91  of pivot-able member  92 , the strength member  82 , and also through the left flat-bar component  93  of the pivot-able member  92 . The handle pinhole  95  allows the user P to insert a pin, bolt, or strap through the handle pinhole  95  to provide a comfortable grip when using the convertible cargo carrier and cart  100  in a variety of preferred applications. 
     While the invention has been particularly shown and described with reference to embodiments thereof, it will be appreciated by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the invention.
A lightweight convertible cargo carrier cart system and accessories adaptable for transporting articles using a vehicle's receiver hitch, or wheeled hand cart, or trailer (pulled via a bicycle or other device). Users can select appropriate components to manage loads based on the available method for transporting the load. Accessories include a handle accessory, a leg/foot accessory, and inserts (for attaching wheels, hardware, and accessories). When the convertible cargo carrier and cart system is used as a cart the user is afforded a variety of positions for installing inserts and wheels based on the weight, mass, and distribution of the load.