Abstract:
A special hitch insert, adapted to receive a rolling cart, can be inserted into a standard vehicle hitch. The hitch insert allows the cart to be loaded at ground level, rolled to the rear of the vehicle, and secured to the hitch insert by using the cart as a lever to raise the cart and lock it onto the hitch insert at the level of the receiving hitch.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
     Not applicable. 
     REFERENCE TO A BIOLOGICAL SEQUENCE LISTING 
     Not applicable. 
     BACKGROUND OF INVENTION 
     1. Field of the Invention 
     This invention is in the field of land vehicles, more specifically in the field of cargo carrying attachments for such vehicles, and still more specifically in the field of detachable cargo carriers which function as land vehicles themselves. It is also in the fields of article carriers, and supports. 
     2. Description of the Related Art 
     Detachable cargo carriers of many kinds, and such carriers which are themselves vehicles, have been used for many years. An example of the former is a box, trunk or cooler fixed to the rear of a vehicle. Examples of the latter are a vehicle towed by another vehicle, and a wheelchair carried in a van. 
     More recently, with the advent of receiving hitches being installed below the rear bumpers of vehicles (typically pickup trucks) rectangular horizontal carriers and trays have been created with a hitch insert on the front side. When the hitch insert is inserted into the receiving hitch, a tray approximately bumper high is available upon which to load articles for transport. A variant of this device incorporates a folding ramp on another side of the tray, permitting a motorcycle, wheelchair, etc. to be rolled from ground level up onto the tray. 
     A drawback of these devices are that they are often heavy and cumbersome to install into the receiving hitch and so, once installed, they tend to be left in place as an extension of the rear of the vehicle even when not carrying anything. This poses problems with parking and other vehicle maneuvering. Another drawback is that, in the absence of a ramp, or when articles to be carried cannot be rolled up a ramp, they have to be lifted from the ground to the tray. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Objects of the Invention 
     There is thus a need for a carrier that can be installed and removed easily by one person, and that can be loaded near ground level before being installed into a receiving hitch. 
     SUMMARY OF THE INVENTION 
     The present invention is a combination of a carrying cart and hitch insert for a vehicle having a receiving hitch. The hitch insert is relatively small and lightweight and may either be installed and removed as needed from the receiving hitch or left in place without presenting a significant maneuvering problem for the vehicle. The carrying cart resembles a hand truck but it is adapted to be secured simply and securely to the hitch insert. The cart can be loaded at ground level, rolled to the rear of the vehicle, and secured to the hitch insert by using the cart as a lever to raise it and lock it at the level of the receiving hitch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a left rear oblique view of the first embodiment of the invention installed on a vehicle. 
         FIG. 2  is a left side view of the first embodiment installed on a vehicle. 
         FIG. 3  is a left rear oblique view of the lower end of the hitch insert portion of the invention. 
         FIG. 4  is a side view of the cart portion of the invention being installed on the hitch insert portion of the first embodiment of the invention. 
         FIG. 5  is a left side view of the cart portion of the invention being raised toward a locking position on the first embodiment of the hitch insert portion of the invention. 
         FIG. 6  is a left side view of the cart portion of the invention locked on the first embodiment of the hitch insert portion of the invention. 
         FIG. 7  is a left side view of the first step of releasing the cart portion of the invention from the first embodiment of the hitch insert portion of the invention. 
         FIG. 8  is a left side view of the second step of releasing the cart portion of the invention from the first embodiment of the hitch insert portion of the invention. 
         FIG. 9  is a right rear oblique view of the hitch insert portion of the second embodiment of the invention locking the cart portion of the invention in place. 
         FIG. 10  is a right rear oblique view of the hitch insert portion of the second embodiment of the invention releasing the cart portion of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, in which like reference characters refer to like elements among the drawings,  FIG. 1  shows a left rear oblique view of the first embodiment of the invention installed on a vehicle. The rear of a vehicle  16  is shown having a receiving hitch  12  affixed below the rear bumper. The vehicle  16  and the receiving hitch  12  are shown in dashed lines as environmental structure. Receiving hitches are commonplace on towing vehicles, utilized for attaching a towing implement to the vehicle such as a hitch ball for towing a trailer (not shown). The present invention consists of a hitch insert  1  and a cart  14 . 
       FIG. 2  is a left side view of the first embodiment installed on a vehicle. The hitch insert portion  1  comprises a horizontal bar  17  sized to fit the receiving hitch  12 , both of which have aligned tow pin holes  2  for receiving a tow pin (not shown). A vertical post  18  is welded to the bar  17 . Part way up post  18  are right and left collars  5  welded to the post. A straight primary latch pin  4  is inserted through holes bored through both collars to receive the pin. Near the top of post  18  is a U-shaped counterweight  10  that pivots about first pivot  9 . Just below counterweight  10  is a rounded rectangular secondary latch  8  pivotable about second pivot  7 . Both counterweight  10  and secondary latch  8  are prevented from rotating clockwise beyond the horizontal by retaining pin  6 . At the rearmost end (rightmost in this view) of the bar  17  is a pair of shaped retainers  3  welded to the top surface of bar  17 , which serve to guide cart  14  into place for securing it to hitch insert portion  1 . The hitch insert portion  1  and the foregoing components distinguish the two embodiments herein described from each other. 
     The drawings show some portions as solid, some as angle iron or other shapes. It should be understood that solid pieces may be hollow, angle iron may be solid bars or channels, etc. all within the scope of the present invention. 
       FIG. 2  also shows the cart portion  14  of the invention. It comprises an article supporting part  20 , here shown as a solid flat platform, rear wheels  11 , a forward stand  13 , an upright handle  15 , and a grip  16 . The scope of the present invention includes any configuration of platform that can support articles placed on it. It need not be rectangular, and it may include vertical walls or special article-holding features such as pegs, straps, a weather enclosure, etc. without limitation as long as they do not interfere with the function of the means of attachment of the cart portion to the hitch insert portion as described below. The scope of the present invention also includes handle configurations other than that shown, a wheel or wheels in place of forward stand  13 , skids instead of wheels, etc. as long as such options allow the below-described functionality of the means of attachment of the cart portion to the hitch insert portion. 
     At the forward end of cart portion  14  is a shaped pillar  21  which engages cart portion  14  to hitch insert portion  1 . Pillar  21  has a hole  22  bored through it to accept primary latch pin  4 . At the upper end of pillar  21  is a forward-facing bevel  23 . 
       FIG. 3  is a left rear oblique view of the lower end of the hitch insert portion  1  of the invention. This view shows shaped retainers  3  welded to vertical post  18  and horizontal bar  17 . Between retainers  3  is a forward-facing catch  30  which serves to help position pillar  21  correctly relative to hitch insert portion  1  and provide additional security against rearward motion of cart portion  14  (not shown). 
       FIG. 4  is a side view of the cart portion  14  of the invention being installed on the hitch insert portion  1  of the first embodiment of the invention. After hitch insert portion  1  is installed in and pinned to hitch  12 , the user rotates U-shaped counterweight  10  clockwise about first pivot  9  so that it rests upon the rearward portion of secondary latch  8  as shown. With proper weighting of counterweight  10  and secondary latch  8 , their combined center of gravity will then be rearward of second pivot  7 . Next, cart portion  14  is tilted back using handle  15  and rolled into position behind the vehicle on wheels  11  along the ground  40  behind the vehicle. The lower end of pillar  21  is positioned between shaped retainers  3  and moved back and forth slightly until catch  30  (not visible in this view) enters a corresponding notch (not visible) underneath pillar  21 . Handle  15  is then raised, rotating cart portion  14  and pillar  21  counterclockwise. 
       FIG. 5  shows pillar  21  approaching the vertical, locking orientation. When the upper surface of pillar  21  contacts secondary latch  8 , its beveled surface raises both secondary latch  8  and counterweight  10 . 
       FIG. 6  shows that when pillar  21  reaches a nearly vertical orientation, secondary latch  8  clears the top of pillar  21  and falls into position behind pillar  21  because the combined center of gravity of secondary latch  8  and counterweight  10  are to the right of second pivot  7 . Secondary latch  8  then holds pillar  21  upright so that latch pin  4  can be inserted through hole  22 . Wheels  11  will then be well clear of the ground. It must be noted that the precise shapes of the counterweight  10  and secondary latch  8  need not be U-shaped and a rounded rectangle, respectively, so long they are shaped to be raised by the bevel  23  when it moves toward post  18  and fall behind pillar  21  and prevent it from moving away from post  18 . 
       FIG. 7  shows the first step in releasing the cart portion  14  from the hitch insert portion  1 , namely, that the user flips counterweight  10  to the left (counterclockwise about first pivot  9 ). This places the combined center of gravity of secondary latch  8  and counterweight  10  to the left of second pivot  7 . The user then pulls the latch pin  4  so that only secondary latch  8  is holding the cart portion up. 
       FIG. 8  shows that when the user lifts the handle  15  on the cart portion (not shown in this view) a small amount, counterweight  10  causes secondary latch  8  to rotate counterclockwise, out of the way of pillar  21 . The user can then lower the wheels at the rear of the cart portion to the ground. 
       FIG. 9  is a right rear oblique view of the hitch insert portion of the second embodiment of the invention locking the cart portion  14  of the invention in place. This second embodiment differs from the first in that there is no secondary latch, and instead of a counterweight, a primary latch  90  is provided that contains a movable counterweight in the form of a sliding bolt  91 . The sliding bolt  91  can be moved by bolt handle  92 , and by proper weighting of the components, when bolt  91  is fully to the left as shown, the combined center of gravity of latch  90  and bolt  91  is to the left of pivot  9 . Primary latch  90  is restrained from rotating past the horizontal in the counterclockwise direction by retaining pin  6 . 
     As in the first embodiment, when cart portion  14  is installed onto hitch insert  14 , the beveled top of pillar  21  raises latch  90  when cart portion  14  is lifted sufficiently, and allows it to fall back into the horizontal position, holding pillar  21  in place so that latch pin  4  can be inserted. Note the safety feature provided by bolt handle  92  and bolt handle notch  93 . Bolt  91  cannot move to the right without human intervention, because gravity keeps bolt handle  92  oriented vertically in bolt handle notch  93 . 
     To release the cart portion  14 , bolt handle  92  is rotated upward and bolt  91  is pushed forward (to the right in this view) shifting the center of gravity of latch  90  to the right of pivot  9 . However, the weight of the cart portion  14  pulls pillar  21  against latch  90 , keeping pillar  21  vertical so that latch pin  4  can then be removed. 
       FIG. 10  illustrates what happens when the user lifts the cart handle, taking the weight off pillar  21 . The latch  10  pivots clockwise, releasing pillar  21 , and allowing the rear of cart portion  14  to be lowered to the ground.