Abstract:
A vehicle loadable cart for loading into a trunk of a vehicle, having a floor and a rear wall which is higher than the floor, is disclosed. The cart includes a chassis, a retractable main wheel assembly for supporting the chassis when transported over a ground surface, and at least one auxiliary wheel assembly with a deployment mechanism that is adapted to shift the auxiliary wheel assembly between a retracted state, in which the auxiliary wheel assembly is raised so as to allow the chassis to pass in a substantially horizontal position over the rear wall of the trunk, and a deployed state, in which said at least one auxiliary wheel assembly extends downward so as to support the chassis above the trunk floor at an elevation equal to or higher than the rear wall of the trunk, allowing wheeling the cart further into the trunk. When the cart is inside the trunk said at least one auxiliary wheel assembly may be retracted to lower the chassis onto the floor of the trunk.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to carts. More particularly, the present invention relates to a vehicle loadable cart. 
       BACKGROUND OF THE INVENTION 
       [0002]    Carts are widely used in moving goods to and from automobiles and other vehicles. In general, a cart has a basket mounted on legs or a chassis provided with wheels or casters. Often, it is desirable to transport the cart together with its contents. The height of many carts, especially those carts intended for use by shoppers, is designed such that the cart may be comfortably filled, pushed, and emptied by a person of ordinary height. The desired height of the cart is generally achieved by making the legs of the cart sufficiently long so that the basket of the cart is at the desired height. Often, a cart whose height is convenient for shopping is too tall to fit as is into the cargo compartment of a typical passenger vehicle. For this reason, collapsible carts have been proposed. 
         [0003]    For example, Duerr in EP1733947 and D&#39;Angelo in US 2003/0197339 describe carts that are collapsible to a compact form for convenient stowing. However, the cart cannot be collapsed when filled, and must be emptied of its contents prior to being collapsed. Niehus in DE 20303702 describes a partially collapsible cart in which the basket may be lowered. No provision is made, however, for conveniently loading the partially collapsed cart into a vehicle. 
         [0004]    Designs have been proposed for carts that may be loaded with their contents into vehicles. For example, Nugent in US 2008/0061531 describes a cart that can be pushed horizontally into a vehicle while simultaneously collapsing the legs of the cart. Miller in U.S. Pat. No. 6,575,491, Gines in U.S. Pat. No. 6,070,899, Navelier in FR 2850623, and Vasseur in FR 2775645 describe carts with wheels that extend forward near the bottom of the cart basket. The extended wheels are placed on the floor of the cargo area of the vehicle. The cart is then pushed forward horizontally into the vehicle while collapsing the legs of the cart. The wheels of the cart, or additional wheels provided on the legs, facilitate pushing the cart once the legs are partially or fully collapsed. These designs allow for convenient horizontal loading of the cart into a flat, open cargo compartment of a vehicle. Thus, convenient use of a cart with one of these designs is limited to vehicles that enable horizontal access to a flat cargo compartment, such as vans or station wagons. Such a cart cannot be conveniently loaded into the trunk of a sedan or other cargo compartment with a rear wall that blocks horizontal access to the compartment. In order to load the cart into a trunk, the cart would have to be lifted over the rear wall of the trunk. 
         [0005]    Al-Toukhi in U.S. Pat. No. 6,045,150 describes a cart designed for stowing in the trunk of an automobile. In this design, a handle extends horizontally forward from the front legs of the cart. The front end of the cart is brought adjacent to the rear wall of the trunk of the automobile. The front legs of the cart are then folded up and back toward the bottom of the cart basket, such that the handle extends downward into the trunk. When the front legs are fully folded, the handle supports the front end of the basket. A pair of support legs that are attached perpendicularly to the front legs of the cart supports the rear end of the basket. The rear legs are folded up and over the rear end of the basket such that the ends of rear legs rest inside the basket. Therefore, a fully loaded cart must be at least partially emptied prior to loading into the trunk. No provision is made for supporting the front end of the basket during the process of folding the front legs of the cart. Also, the rear end of the basket must be lifted so that the supplemental support legs can clear the rear wall of the trunk. Therefore, a person who is not strong enough to lift the cart when it is loaded cannot place the loaded cart into the trunk while unassisted. 
         [0006]    Therefore, there is a need for a cart that may be placed, while fully loaded, into the trunk of a vehicle by a single person, unassisted. 
         [0007]    It is an object of the present invention to provide a cart that may be placed fully loaded by a single unassisted person into the trunk of a vehicle. 
         [0008]    Other aims and advantages of the present invention will become apparent after reading the present invention and reviewing the accompanying drawings. 
       SUMMARY OF THE INVENTION 
       [0009]    There is thus provided, in accordance with some embodiments of the present invention, a vehicle loadable cart for loading into a trunk of a vehicle having a floor and a rear wall which is higher than the floor, the cart comprising: 
         [0010]    a chassis; 
         [0011]    a retractable main wheel assembly for supporting the chassis when transported over a ground surface; 
         [0012]    at least one auxiliary wheel assembly with a deployment mechanism that is adapted to shift the auxiliary wheel assembly between a retracted state in which the auxiliary wheel assembly is raised so as to allow the chassis to pass in a substantially horizontal position over the rear wall of the trunk, and a deployed state in which said at least one auxiliary wheel assembly extends downward so as to support the chassis above the trunk floor at an elevation equal to or higher than the rear wall of the trunk, allowing wheeling the cart further into the trunk, 
         [0013]    whereby when the cart is inside the trunk said at least one auxiliary wheel assembly may be retracted to lower the chassis onto the floor of the trunk. 
         [0014]    Furthermore, in accordance with embodiments of the present invention, said at least one auxiliary wheel assembly comprises a front auxiliary wheel assembly for supporting a front portion of the chassis above the trunk floor. 
         [0015]    Furthermore, in accordance with embodiments of the present invention, the retractable main wheel assembly and said at least one auxiliary wheel assembly cooperate. 
         [0016]    Furthermore, in accordance with embodiments of the present invention, said at least one auxiliary wheel assembly comprises a front auxiliary wheel assembly and a rear auxiliary wheel assembly. 
         [0017]    Furthermore, in accordance with embodiments of the present invention, the retractable main wheel assembly includes front legs and rear legs. 
         [0018]    Furthermore, in accordance with embodiments of the present invention, the deployment mechanism is manually operable. 
         [0019]    Furthermore, in accordance with embodiments of the present invention, the deployment mechanism is manually operable by a lever. 
         [0020]    Furthermore, in accordance with embodiments of the present invention, the deployment mechanism includes a stored-energy element for assisting in the deployment of said at least one auxiliary wheel assembly. 
         [0021]    Furthermore, in accordance with embodiments of the present invention, the stored-energy element comprises a spring. 
         [0022]    Furthermore, in accordance with embodiments of the present invention, said at least one auxiliary wheel assembly is adjustable so as to adjust the elevation. 
         [0023]    Furthermore, in accordance with embodiments of the present invention, the retractable main wheel assembly is adjustable so as to adjust the height of the chassis above the ground surface. 
         [0024]    Furthermore, in accordance with embodiments of the present invention, the deployment mechanism is automatic. 
         [0025]    Furthermore, in accordance with embodiments of the present invention, the deployment mechanism comprises a motor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    In order to better understand the present invention, and appreciate its practical applications, the following Figures are provided and referenced hereafter. It should be noted that the Figures are given as examples only and in no way limit the scope of the invention. Like components are denoted by like reference numerals. 
           [0027]      FIG. 1  schematically illustrates a vehicle loadable cart in accordance with some embodiments of the present invention. 
           [0028]      FIG. 2A  schematically illustrates deployment mechanism of a front auxiliary wheel assembly mechanism of the cart shown in  FIG. 1 . 
           [0029]      FIG. 2B  schematically illustrates a release mechanism for the deployment mechanism shown in  FIG. 2A . 
           [0030]      FIG. 2C  schematically illustrates an unlocked state of the release mechanism shown in  FIG. 2B . 
           [0031]      FIG. 3  schematically illustrates a mechanism for retracting the auxiliary wheel assembly of the cart shown in  FIG. 1 . 
           [0032]      FIG. 4A  is a schematic side view of the cart shown in  FIG. 1  when in position to be loaded into the trunk of a vehicle. 
           [0033]      FIG. 4B  schematically illustrates the cart shown in  FIG. 4A  with the front support legs deployed. 
           [0034]      FIG. 4C  schematically illustrates the cart shown in  FIG. 4B  in position to collapse the rear cart legs. 
           [0035]      FIG. 4D  schematically illustrates the cart shown in  FIG. 4C  with all support legs deployed. 
           [0036]      FIG. 4E  schematically illustrates the cart shown in  FIG. 4D  with support legs retracted. 
           [0037]      FIG. 5  schematically illustrates a vehicle loadable cart with slanted front legs in accordance with some embodiments of the present invention. 
           [0038]      FIG. 6A  schematically illustrates a mechanism for deploying the front support legs of the cart shown in  FIG. 5 . 
           [0039]      FIG. 6B  schematically illustrates the mechanism of  FIG. 6A  with the front support legs deployed. 
           [0040]      FIG. 7A  schematically illustrates a mechanism for deploying the rear support legs of the cart shown in  FIG. 5 . 
           [0041]      FIG. 7B  schematically illustrates the mechanism of  FIG. 7A  with the rear support legs deployed. 
           [0042]      FIG. 8A  is a schematic side view of the cart shown in  FIG. 5  when in position to be loaded into the trunk of a vehicle. 
           [0043]      FIG. 8B  schematically illustrates the cart shown in  FIG. 8A  with the front cart legs retracted. 
           [0044]      FIG. 8C  schematically illustrates the cart shown in  FIG. 8B  with the front support legs deployed. 
           [0045]      FIG. 8D  schematically illustrates the cart shown in  FIG. 8C  in position to retract the rear cart legs. 
           [0046]      FIG. 8E  schematically illustrates the cart shown in  FIG. 8D  with the rear main wheel assembly retracted. 
           [0047]      FIG. 8F  schematically illustrates the cart shown in  FIG. 8E  with all support legs deployed. 
           [0048]      FIG. 8G  schematically illustrates the cart shown in  FIG. 8F  entirely within the trunk of a vehicle. 
           [0049]      FIG. 8H  schematically illustrates the cart shown in  FIG. 8G  with support legs retracted. 
           [0050]      FIG. 9  schematically illustrates a vehicle loadable cart with slanted front legs and separate handles for deploying support legs, in accordance with some embodiments of the present invention. 
           [0051]      FIG. 10A  is a schematic side view of the cart shown in  FIG. 9  when in position to be loaded into the trunk of a vehicle. 
           [0052]      FIG. 10B  schematically illustrates the cart shown in  FIG. 10A  with front support legs deployed. 
           [0053]      FIG. 10C  schematically illustrates the cart shown in  FIG. 10B  with front legs retracted. 
           [0054]      FIG. 10D  schematically illustrates the cart shown in  FIG. 10C  with horizontally folded retracted front legs. 
           [0055]      FIG. 10E  schematically illustrates deploying the rear support legs of the cart shown in  FIG. 8D . 
           [0056]      FIG. 10F  schematically illustrates the cart shown in  FIG. 10E  with all support legs deployed. 
           [0057]      FIG. 10G  schematically illustrates the cart shown in  FIG. 10F  with rear legs retracted. 
           [0058]      FIG. 10H  schematically illustrates the cart shown in  FIG. 10G  with horizontally folded retracted rear legs. 
           [0059]      FIG. 10I  schematically illustrates retracting the support legs of the cart shown in  FIG. 10H . 
           [0060]      FIG. 10J  schematically illustrates the cart shown in  FIG. 10I  with support legs retracted. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0061]    A vehicle loadable cart in accordance with embodiments of the present invention is designed to be placed into the trunk of a vehicle while fully loaded or empty. The cart includes a chassis that typically includes a main wheel assembly on which the chassis is wheeled across a supporting ground. A receptacle into which objects may be placed, such as a basket, may be mounted on the chassis. Alternatively, the chassis may support a reusable flexible bag or a rigid case. The bag may be constructed of heavy cloth, plastic, or any other durable, flexible, and washable material. The bag may be closable by means of a zipper, or other appropriate closing mechanism. 
         [0062]    The main wheel assembly may include a pair of front cart legs and a pair of rear cart legs The bottom ends of the legs are provided with wheels or casters. A push handle is provided at a convenient height so as to enable a person of ordinary height to comfortably push the cart. The legs are sufficiently long so as to enable a person of ordinary height to comfortably place objects into the receptacle, or to remove objects from the receptacle, while standing adjacent to the cart. Thus, a person may comfortably fill the receptacle and bring the loaded cart to the trunk of a vehicle. The main wheel assembly is retractable. When the main wheel assembly is retracted, the chassis may be supported by one or more auxiliary wheel assemblies as described below. When the auxiliary wheel assemblies are also retracted, the chassis rests on the surface on which it is placed. In the context of this description, “retractable” and “retracting” refer to any manner of folding, collapsing, withdrawing, hiding away, or any other method of causing an assembly to no longer be deployed. The height of the main wheel assembly may be adjustable so as to adjust the height of the chassis. The height may be adjusted, for example, for the convenience of a person using the cart, or to pass horizontally over the wall of the trunk. 
         [0063]    The design of the cart enables a single unassisted person to place the loaded cart into the trunk of a vehicle. This is accomplished by providing the cart with one or more deployable auxiliary wheel assemblies to support the chassis above the floor of the trunk. In some embodiments of the present invention, one auxiliary wheel assembly may be provided to support one part (typically the front portion) of the chassis. Alternatively, two auxiliary wheel assemblies may be provided, one designed to support the front portion of the cart, and the other to support the rear portion of the cart. An auxiliary wheel assembly includes one or more (typically two) short deployable support legs that are deployed from the front or rear of the cart chassis. The front of the loaded cart is brought up to the opening of the trunk, near the rear wall of the trunk. The front deployable support legs, which may initially be in a retracted state beneath the cart, are then deployed, extending from the front of the cart to the floor of the trunk. The deployed front support legs hold the front end of the chassis above the rear wall of the trunk. In embodiments of the present invention, the length of the front and rear support legs may be adjustable so as to adapt the auxiliary wheel assemblies, and specifically the support legs to the trunk of a specific vehicle. The support legs are provided with casters in order to enable the support legs to roll on the floor of the trunk. The front support legs support the front end of the chassis as part or all of the main wheel assemblies are folded to a stowed state. For example, the front legs of the cart may be collapsed, folded, or retracted. Depending on the embodiment of the present invention, the front support legs are deployed prior to or concurrently with retraction of the front cart legs. In some embodiments of the present invention, folding the front cart legs, or applying a force to fold the front cart legs, causes the front support legs to deploy concurrently with the folding of the front cart legs. Alternatively, the front support legs are deployed by means of a separate mechanism. The front support legs may be extended by a spring loaded mechanism, or other similar mechanism with a stored energy element. In some embodiments of the present invention, the front end of the chassis may rest on the rear wall of the trunk during retraction of the front cart legs until the front support legs are fully deployed. The height of each support leg plus the height of the floor of the trunk is designed to be approximately equal to the height of each rear leg, or designed to be adjustable to facilitate that relation. Thus, when the chassis is being supported by the front support legs and the rear cart legs of the main wheel assembly, and when the surface on which the cart and the vehicle are standing is substantially level, the chassis is held substantially level. Collapsing the front legs enables the chassis to be pushed horizontally forward, further into the trunk. 
         [0064]    When the chassis has been pushed sufficiently into the trunk, the pair of rear support legs may be deployed so as to extend from the rear of the chassis to the floor of the trunk. The rear support legs support the rear end of the chassis while the rear legs of the main wheel assembly of the cart are being collapsed, folded, or retracted. Depending on the embodiment of the present invention, the rear support legs are deployed before or concurrently with retraction of the rear legs of the main wheel assembly. In some embodiments of the present invention, the rear portion of the chassis may rest on the rear wall of the trunk during retraction of the rear cart legs until the rear support legs are fully deployed. In some embodiments of the present invention, the legs of the main wheel assembly cooperate with the support legs of the auxiliary wheel assemblies. With cooperating wheel assemblies, operating the main wheel assembly (f example, retracting or folding the main wheel assembly or part thereon) causes deployment or retraction of an auxiliary wheel assembly. For example, folding the rear cart legs, or applying a force to fold the rear cart legs, causes the rear support legs to deploy automatically. Alternatively, the rear support legs are deployed manually by means of a separate mechanism, such as a lever or handle. The rear support legs may be deployed by means of a spring loaded mechanism or other stored energy element. The remainder of the chassis may then be pushed horizontally into the trunk. When the chassis is fully within the trunk of the vehicle, both pairs of support legs may be retracted. Retracting the support legs causes the chassis to be lowered to the floor of the trunk. Lowering the chassis to the floor of the trunk may be necessary in order to allow the cover of the trunk to close. In addition, resting the bottom of the chassis on the floor of the trunk, rather than on the support legs and casters, increases the stability of the chassis and immobilizes it. This may prevent the chassis from sliding or tipping over when the vehicle is in motion. 
         [0065]    In order to remove the cart from the trunk of the vehicle, the procedure is reversed: The front and rear support legs are extended. In embodiments of the present invention, a spring loaded or other stored energy element mechanism may be provided to assist in extending the support legs when the cart legs are collapsed. With a spring loaded mechanism, a person operates a release mechanism to enable the spring loaded mechanism to assist in extending the support legs. The spring loaded mechanism (or other powered mechanism that includes an energy stored element, such as, for example, pneumatic mechanism, hydraulic mechanism) minimizes the effort that must be expended by a person in order to extend the support legs when the cart legs are collapsed. The person then begins to pull the chassis horizontally toward the rear of the trunk. When the rear end of the chassis extends over the rear trunk wall out of the trunk, the user lowers and deploys the rear cart legs. In some embodiments of the present invention, deploying the rear cart legs causes the rear support legs to retract. In other embodiments of the present invention, the rear support legs are retracted by means of a separate mechanism after the rear cart legs have been deployed. In some embodiments of the present invention, the rear end of the chassis rests on the rear trunk wall until the rear cart legs are fully deployed. Retracting the rear support legs enables the rear end of the cart to be pulled horizontally further out of the trunk, supported by the rear cart legs and the front support legs. As the front of the chassis is removed from the trunk, the front cart legs are deployed. In some embodiments of the present invention, deploying the front cart legs causes the front support legs to retract. In other embodiments of the present invention, the front support legs are retracted by means of a separate mechanism after the front cart legs have been deployed. In some embodiments of the present invention, the rear end of the chassis rests on the rear trunk wall until the rear cart legs are fully deployed. Deploying the front cart legs and retracting the front support legs enables the cart to be pulled completely out of the trunk, and away from the vehicle. A locking mechanism may be provided to lock the front and rear cart legs in the deployed position, preventing accidental collapse of the cart legs. 
         [0066]    During placement of the cart into a trunk and removal of the cart from the trunk, it is desired that a person not be required to lift or support the chassis at any time. Thus, embodiments of the present invention enable an unassisted user who is not capable of lifting or supporting the cart with its contents to load, or unload, the cart with its contents into the trunk of a vehicle. 
         [0067]      FIG. 1  schematically illustrates a vehicle loadable cart in accordance with some embodiments of the present invention. Chassis  12  of cart  10  rests on front cart legs  14   a  and rear cart legs  14   b . In general, the construction of cart  10  may be symmetrical from right to left. The bottom ends of front cart legs  14   a  are provided with front wheels  15   a , and rear cart legs  14   b  are provided with rear wheels  15   b . Push handle  18  is attached to chassis  12 , and enables a user to cause cart  10  to roll on wheels  15   a  and  15   b . Chassis  12  includes chassis bottom  13  and side walls  20 . Each of side walls  20  is double. Each side wall  20  includes an inner wall panel  21   a  and an outer wall panel  21   b . Various components of a leg deploying and collapsing mechanism, for example handles  22 , may be mounted in the space between inner wall panel  21   a  and outer wall panel  2   1   b , so as to hide it away and restrict accessing it. 
         [0068]    During the course of loading cart  10  into the trunk of a vehicle, front support legs  24   a  and rear support legs  24   b  are deployed.  FIG. 2A  schematically illustrates a deployment mechanism of a front auxiliary wheel assembly mechanism of the cart shown in  FIG. 1 . Folding front cart legs  14   a  operates the mechanism for deploying front support legs  24   a . Folding front cart leg  14   a  upward and rearward (toward the rear of the cart) turns gear wheel  26   a . Rotation of gear wheel  26   a  causes rotation of gear  34   a , in turn causing rotation of gear  32   a . Rotation of gear  32   a  causes support leg  24   a  to extend frontward (toward the front of the cart) and downward. Folding rear cart leg  14   b  causes similar rotation of gear wheel  26   b , gear  34   b , and gear  32   b , similarly extending rear support leg  24   b  frontward and downward. Right and left front cart legs  14   a  may be connected to one another by means of one or more horizontal or diagonal bars. In addition, or alternatively, gear  34   a  or gear  32   a  on one side of the cart may be connected by means of an axle to a symmetrically placed gear on the opposite side of the cart. Such a connection may enable concurrent and even deployment of front support legs  24   a  on both the right and left sides of the cart. 
         [0069]    In some embodiments of the present invention, contact of a cart leg (front or rear) with the rear bumper of a vehicle triggers a pressure sensitive release mechanism mounted on one or both of a pair of cart legs. The release mechanism enables that leg to fold and the associated support legs of the auxiliary wheel assembly to deploy.  FIG. 2B  schematically illustrates a release mechanism for the deployment mechanism shown in  FIG. 2A . Ordinarily, when cart leg  14  is extended, bolt  23  extends into recess  21 , preventing rotation of gear wheel  26  and folding of cart leg  14 . Thus, the cart leg is locked in an extended state. An optional user-operated locking mechanism (not shown) may prevent accidental removal of bolt  23  from recess  21  by accidental triggering of the release mechanism. The user-operated locking mechanism may be located on the handle of the cart, or any other location convenient for a user. When cart leg  14  is brought into contact with the rear bumper of a vehicle, trigger  19  is pressed. Pressing trigger  19  causes, for example, by means of a rack and pinion mechanism  29 , joint  27  to rotate downward. Downward rotation of joint  27  pulls shaft  25  and bolt  23  downward. Pulling bolt  23  downward removes bolt  23  from recess  21 , unlocking gear wheel  26 .  FIG. 2C  schematically illustrates an unlocked state of the release mechanism shown in  FIG. 2B . When in the unlocked state, further pressing on the cart legs may cause the cart legs to fold upward, extending the associated support legs of the auxiliary wheel assembly. Alternatively, the leg locking and release mechanism may employ another mechanism to enable locking and folding of the cart legs, including a spring-loaded, cable, latch, or other mechanical mechanism, or an electromagnetic, pneumatic, hydraulic, or any other suitable mechanism known in the art for locking and releasing the cart legs. The release mechanism may be triggered by a signal generated by a mechanical, electromagnetic, acoustic, optical, or other sensor that detects the proximity of the cart to the trunk of a vehicle. 
         [0070]    Alternatively to the mechanism shown in  FIG. 2A  for extending the support legs of the auxiliary wheel assembly, a spring-loaded, pneumatic, electromagnetic, electromechanical, motorized, or other automatically operable deployment mechanism may extend the support legs frontward and downward. The deployment of the automatic deployment mechanism may be triggered by a manual mechanism such as a handle or lever or by folding the cart legs. Alternatively, the deployment of the automatic deployment mechanism may be triggered by an automatic mechanism such as the cart leg release mechanism, by a signal generated by a proximity sensor, or other suitable triggering mechanism known in the art. When the spring loaded deployment mechanism has caused the support legs to extend sufficiently (e.g. can support the cart chassis above the wall of a trunk), a latch, ratchet, or other locking mechanism may lock the support legs in their extended, deployed position. With such an automatic deployment mechanism, front support legs  24   a  may be deployed so as to support the front end of the chassis prior to the folding of front cart legs  14   a . A similar automatic deployment mechanism may deploy rear support legs  24   b  prior to the folding of rear cart legs  14   b.    
         [0071]    Once the cart is loaded into the trunk of a vehicle, the support legs are retracted so that the bottom of the chassis rests on the floor of the trunk.  FIG. 3  schematically illustrates a mechanism for retracting the support legs of the cart shown in  FIG. 1 . The cart legs, such as front cart leg  14   a , are in their folded positions. In order to retract support legs  24   a  and  24   b , handle  22  is rotated toward the rear of the cart. Rotating handle  22  toward the rear turns wheel  28 . Wheel  28  is located between inner wall panel  21   a  and outer wall panel  21   b . Rotation of wheel  28  moves rod  30   b  to the rear and rod  30   a  to the front. Rearward motion of rod  30   b  rotates gear wheel  26   b , causing rotation of gear  34   b , which in turn causes rotation of gear  32   b . Rotation of gear  32   b  causes rear support leg  24   b  to retract upward and rearward. Similarly, the frontward motion of rod  30   a  causes rotation of gear wheel  26   a , gear  34   a , and gear  32   a , and retraction of front support leg  24   a.    
         [0072]    In some embodiments of the present invention, retracting support legs  24   a  and  24   b  loads one or more spring-loaded or other stored energy mechanisms (not shown). At a later time, when a release mechanism is triggered, the loaded spring mechanisms may extend and deploy the support legs. Alternatively, the spring mechanism may be replaced by a hydraulic, compressed gas, or any other stored energy element mechanism capable of applying a restoration force to extend the support legs. 
         [0073]    Mechanisms for deploying and retracting the support legs enable an unassisted user to place a loaded cart into the trunk of a vehicle. A procedure for placing cart  10  into the trunk of a vehicle is illustrated in  FIG. 4A-FIG .  4 E.  FIG. 4A  is a schematic side view of the cart shown in  FIG. 1  when in position to be loaded into the trunk of a vehicle. The front end of cart  10  is brought up to rear trunk wall  52  of trunk  50  of a vehicle. As cart  10  is pushed forward toward trunk  50 , front cart legs  14   a  are folded rearward and upward. Folding front cart legs  14   a  rearward and upward deploys front support legs  24   a  by means of the mechanism illustrated in  FIG. 2A . In some embodiments of the present invention, a person folds front cart legs  14   a  manually. Alternatively, contact between front cart legs  14   a  and rear bumper  51  of the vehicle causes (for example, by means of the mechanism shown in  FIG. 2A ) front support legs  24   a  to deploy, and front cart legs  14   a  to fold rearward and upward. Front support legs  24   a  extend forward and downward until front support legs  24   a  extend over rear trunk wall  52  to trunk floor  54 . In some embodiments of the present invention, an automatic mechanism automatically deploys front support legs  24   a . In such a case, the bottom ends of front support legs  24   a , when first deployed, may be suspended a short distance, for example, one centimeter or less, above trunk floor  54 . Folding front cart legs  14   a  then lowers the front end of chassis  12  through the short distance. 
         [0074]      FIG. 4B  schematically illustrates the cart shown in  FIG. 4A  with the front support legs deployed. The front end of chassis  12  is supported by front support legs  24   a , while the rear end of chassis  12  is supported by rear cart legs  14   b . Cart  10  may now be pushed horizontally forward into trunk  50 .  FIG. 4C  schematically illustrates the cart shown in  FIG. 4B  in position to collapse the rear cart legs. Rear cart legs  14   b  now abut rear bumper  51 . Rear cart legs  14   b  are folded rearward and upward. Rear cart legs  14   b  are bent at joint  17 , enabling the lower part of rear cart legs  14   b  and rear wheels  15   b  to fold over the top of chassis  12 . Folding rear cart legs  14   b  rearward and upward deploys rear support legs  24   b . Rear support legs  24   b  extend forward and downward over rear trunk wall  52  to trunk floor  54 . In some embodiments of the present invention, a spring-loaded, or other automatic, mechanism deploys rear support legs  24   b . In such a case, the bottom ends of rear support legs  24   b , when first deployed, may be suspended a short distance, for example, one centimeter or less, above trunk floor  54 . Folding rear cart legs  14   b  then lowers the rear end of chassis  12  through the short distance. 
         [0075]      FIG. 4D  schematically illustrates the cart shown in  FIG. 4C  with all support legs deployed. Rear legs  14   b  are folded over the rear end and top of chassis  12 . As shown in  FIG. 4D , chassis  12  has been pushed entirely into trunk  50 . The user now rotates handle  22  toward the rear of the cart. Rotating handle  22  toward the rear causes front support legs  24   a  and rear support legs  24   b  to retract by means of the mechanism illustrated in  FIG. 3 .  FIG. 4E  schematically illustrates the cart shown in  FIG. 4D  with support legs retracted. Chassis  12  is now resting stably on trunk floor  54 . The cover of trunk  50  may now be closed. 
         [0076]    In other embodiments of the present invention, the front cart legs are slanted so as to enable the cart chassis to extend partially into the trunk prior to deploying the front support legs. In this manner, deployed cart legs may extend vertically downward from the bottom of the cart chassis.  FIG. 5  schematically illustrates a vehicle loadable cart with slanted front legs in accordance with some embodiments of the present invention. Chassis  62  of cart  60  rests on front cart legs  64  and rear cart legs  66 . The bottom ends of front cart legs  64  are provided with front wheels  65   a , and rear cart legs  66  are provided with rear wheels  65   b . Handle  68  is connected to front cart legs  64 , and handle  70  is connected to rear cart legs  66 . Chassis  62  includes chassis bottom  74  and side walls  72 . Front cart legs  64  are slanted so as to extend downward and forward from axis  78 , located near the rear of cart  60 . The slant of front cart legs  64  may enable the rear bumper of a vehicle to fit within the space between front cart legs  64  and chassis bottom  74 . This enables the front end of chassis  62  to extend over the top of the rear wall of the trunk of a vehicle (as shown in  FIG. 8A ). Each of side walls  72  consists of three parallel wall panels  73 . Various components of leg deploying and collapsing mechanisms may be located in the spaces between wall panels  73 . 
         [0077]    During the course of loading cart  60  into the trunk of a vehicle, front support legs and rear support legs of an auxiliary wheel assembly are deployed.  FIG. 6A  schematically illustrates a mechanism for deploying the front support legs of the cart shown in  FIG. 5 . As shown in  FIG. 6A , front cart leg  64  is extended and front support leg  96  is folded upward. In order to retract front cart leg  64 , handle  68  is pulled diagonally upward and rearward, pulling front cart legs  64  in the same direction until front wheels  65   a  meet axis  78 . At this point, front cart legs  64  may be shortened by means of a telescoping mechanism. Shortened front cart legs  64  now extend diagonally upward and rearward of axis  78 . Handle  68  and front cart legs  64  are now rotated frontward about axis  78 , turning axis  78 . Rotation of axis  78  swings arm  90  about axis  78 . The motion of arm  90  pushes on arm  92 . Arm  90  is connected to arm  92  by means of one-way joint  91 . One-way joint  91  is capable of bending in one direction only. Motion of the distal end of arm  92  is constrained by confinement of pin  86  to slot  88  (shown in  FIG. 5 ). Therefore, pin  86  slides to the left, and applies a torque to front support leg  96  through arm  94 . Arm  94  is connected to front support leg  96  by means of one-way joint  95 . One-way joint  95  is capable of bending in one direction only. The applied torque causes front support leg  96  to rotate about axis  80 . The rotation of front support leg  96  continues until front support leg  96  and arm  94  are locked by one-way joint  95  in a linearly aligned position extending vertically downward from pin  86 . At this point, arms  90  and  92  are locked by one-way joint  91  in a linearly aligned position extending horizontally. Front caster  65   a  extends downward, and front support leg  96  is deployed.  FIG. 6B  schematically illustrates the mechanism of  FIG. 6A  with the front support legs deployed. Further counterclockwise rotation of front cart leg  64  causes the locked pair of arm  94  and front support leg  96  to rotate. The rotation retracts front support leg  96  and front caster  65   a  into the bottom of a space between wall panels of a side wall of the cart. 
         [0078]      FIG. 7A  schematically illustrates a mechanism for deploying the rear support legs of the cart shown in  FIG. 5 . As shown in  FIG. 7A , rear cart legs  66  are deployed and rear support legs  108  are folded. In order to retract rear cart legs  66 , handle  70  is pulled vertically upward, pulling rear cart legs  66  upward until rear wheels  65   b  meet axis  76 . At this point, rear cart legs  66  may be shortened by means of a telescoping mechanism. Alternatively, each of rear cart legs  66  may include joint (not shown) near the middle of its length. Rear cart legs  66  may then be shortened by being folded at the joint. Shortened rear cart legs  66  now extend vertically upward from axis  76 . Handle  70  and rear cart legs  66  are now rotated frontward about axis  76 , turning axis  76 . Rotation of axis  76  swings arm  100  about axis  76 . The motion of arm  100  pushes on arm  102 . Arm  100  is connected to arm  102  by means of one-way joint  101 . One-way joint  101  is capable of bending in one direction only. Motion of the distal end of arm  102  is constrained by confinement of a pin (not shown) on joint  104  at the distal end of arm  102  to a slot (not shown). Therefore, joint  104  slides to the left, and applies a torque to rear support leg  108  through arm  106 . Arm  106  is connected to front support leg  108  by means of one-way joint  109 . One-way joint  109  is capable of bending in one direction only. The applied torque causes rear support leg  108  to rotate about axis  107 . The rotation of rear support leg  108  continues until rear support leg  108  and arm  106  are locked by one-way joint  109  in a linearly aligned position extending vertically downward from joint  104 . Arms  100  and  102  are locked by one-way joint  101  in a linearly aligned position extending horizontally. Rear caster  65   b  extends downward and rear support leg  108  is deployed.  FIG. 7B  schematically illustrates the mechanism of  FIG. 7A  with the rear support legs deployed. Further rotation of rear cart leg  66  causes the locked pair of arm  106  and rear support leg  108  to rotate further. The further rotation retracts rear support leg  108  and rear caster  65   b  into the bottom of a space between wall panels of a side wall of the cart. 
         [0079]    Mechanisms for deploying and retracting the support legs of an auxiliary wheel assembly enable an unassisted user to place a loaded cart into the trunk of a vehicle. A procedure for placing cart  60  into the trunk of a vehicle is illustrated in  FIG. 8A-FIG .  8 H.  FIG. 8A  is a schematic side view of the cart shown in  FIG. 5  when in position to be loaded into the trunk of a vehicle. The front end of cart  60  is brought up to above rear trunk wall  52  of trunk  50  of a vehicle (only the trunk is shown in this figure). The front end of chassis  62  extends over rear trunk wall  52 , and front cart legs  64  abut rear bumper  51 . Handle  68  is lifted diagonally upward and toward the rear of cart  60 . Lifting handle  68  retracts front cart legs  64  to above axis  78 .  FIG. 8B  schematically illustrates the cart shown in  FIG. 8A  with the front cart legs retracted. The front end of chassis  62  is supported by rear trunk wall  52 . Handle  68  and retracted front cart legs  64  are rotated about axis  78  toward the front of the cart. Rotating handle  68  causes the front support legs to deploy by rotating downward around the front of chassis  62 , by means of the mechanism illustrated in  FIG. 6 . Handle  68  is rotated until the front support legs extend downward from the front of chassis  62 . A stop or click mechanism may be provided in order to prevent unintentional rotation of handle  68  beyond the point that the support legs extend downward.  FIG. 8C  schematically illustrates the cart shown in  FIG. 8B  with the front support legs deployed. Front support legs  96  extend downward from chassis  62 . Front casters  82  are resting on trunk floor  54 . Chassis  62  is now supported by front support legs  96  and rear cart legs  66 . Chassis may be pushed forward on front casters  82  and rear wheels  65   b , further into trunk  50 . 
         [0080]      FIG. 8D  schematically illustrates the cart shown in  FIG. 8C  in position to retract the rear cart legs. Rear cart legs  66  abut rear bumper  51 . Handle  70  is lifted vertically upward, retracting rear cart legs  66  to above axis  76 .  FIG. 8E  schematically illustrates the cart shown in  FIG. 8D  with the rear cart legs retracted. The rear end of chassis  62  is supported by rear trunk wall  52 . Handle  70  and retracted rear cart legs  66  are rotated toward the front of chassis  62  about axis  76 . Rotating handle  70  causes the rear support legs to rotate forward and downward within spaces between wall panels of the side walls of chassis  62 , by means of the mechanism illustrated in  FIG. 7 . Handle  70  is rotated until the rear support legs extend downward from the rear of chassis  62 . A stop or click mechanism may be provided in order to prevent unintentional rotation of handle  70  beyond the point that the support legs extend downward. 
         [0081]      FIG. 8F  schematically illustrates the cart shown in  FIG. 8E  with all support legs deployed. Chassis  62  is supported by front support legs  96  and rear support legs  108 . Chassis  62  may now be pushed forward into trunk  50  on front casters  82  and rear casters  84  until chassis  62  is entirely inside trunk  50 .  FIG. 8G  schematically illustrates the cart shown in  FIG. 8F  entirely within the trunk of a vehicle. In order to improve the stability of chassis  62  when the vehicle is in motion, the support legs are retracted. In order to retract front support legs  96  and rear support legs  108 , handles  68  and  70  are further rotated toward the front end of chassis  62 . Further rotating handles  68  and  70  toward the front end of chassis  62 , causes front support legs  96  and rear support legs  108  to rotate upward and toward the rear of chassis  62  (counterclockwise in  FIG. 8G ). As front support legs  96  and rear support legs  108  rotate upward and rearward, chassis  62  descends. Chassis  62  descends until front support legs  96  and rear support legs  108  rotate into spaces between wall panels of the side walls of chassis  62 .  FIG. 8H  schematically illustrates the cart shown in  FIG. 4G  with support legs retracted. At this point, chassis bottom  74  of chassis  62  is resting stably on trunk floor  54 . The cover (not shown) of trunk  50  may now be closed. 
         [0082]    In other embodiments of the present invention, the support legs are deployed by a mechanism that is independent of the retraction of the cart legs.  FIG. 9  schematically illustrates a vehicle loadable cart with slanted front legs and separate handles for deploying support legs, in accordance with some embodiments of the present invention. Chassis  112  of cart  110  rests on front cart legs  114  and rear cart legs  116 . The bottom ends of front cart legs  114  are provided with front wheels  115   a , and rear cart legs  116  are provided with rear wheels  1   15   b . Handle  118  is connected to front cart legs  114 , and handle  120  is connected to rear cart legs  116 . Chassis  112  includes chassis bottom  124  and side walls  112 . Front cart legs  114  are slanted so as to extend downward and forward from the rear portion of cart  110 . The slant of front cart legs  114  may enable the rear bumper of a vehicle to fit within the space between front cart legs  114  and chassis bottom  124 . This enables the front end of chassis  112  to extend over the top of the rear wall of the trunk of a vehicle (as shown in  FIG. 10A ). Each of side walls  122  is double, consisting of two parallel wall panels  123 . Various components of leg deploying and retracting mechanisms are mounted in the space between wall panels  123 . Handle  136  slides along slot  126 , and is used to extend casters  132  at the ends of front support legs of an auxiliary wheel assembly (see  144  in  FIG. 10B ). Handle  138  slides along slot  128 . When handle  138  is pushed toward the front end of cart  110 , handle  138  slides along slot  128 . Handle  138  pushes on arm  139 , causing rear support leg  140  of an auxiliary wheel assembly to rotate downward around axis  142 . 
         [0083]    A procedure for loading cart  110  into the trunk of a vehicle is illustrated in  FIG. 10A-FIG .  10 J.  FIG. 10A  is a schematic side view of the cart shown in  FIG. 9  when in position to be loaded into the trunk of a vehicle. The front end of cart  110  is brought up to above rear trunk wall  52  of trunk  50  of a vehicle. The front end of chassis  112  extends over rear trunk wall  52 , and front cart legs  114  abut rear bumper  51  of the vehicle. In order to deploy the front support legs, handle  136  is slid toward the front of chassis  112  along slot  126 . Sliding handle  136  forward causes front support legs  144  to rotate forward and downward about axis  146 . Front support legs  144  are thus deployed, extending downward with casters  132  resting on trunk floor  54 .  FIG. 10B  schematically illustrates the cart shown in  FIG. 10A  with front support legs deployed. The front end of chassis  112  is supported by front support legs  144 . At this point, front cart legs  114  may be retracted. Handle  118  is pulled diagonally upward and toward the rear of cart  110 , causing front cart legs  114  to extend above and rearward of axis  117 .  FIG. 10C  schematically illustrates the cart shown in  FIG. 10B  with front legs retracted. Handle  118  is now rotated about axis  117  toward the front of cart  110  until front cart legs  114  are folded horizontally within the space between wall panels  123  (shown in  FIG. 9 ).  FIG. 10D  schematically illustrates the cart shown in  FIG. 10C  with horizontally folded retracted front legs. 
         [0084]    Chassis  112  is now supported by front support legs  144  and rear cart legs  116 . Chassis  112  may be pushed forward on front casters  132  and rear wheels  115   b , further into trunk  50 . When rear cart legs  116  abut rear bumper  51 , the rear support legs may be deployed.  FIG. 10E  schematically illustrates deploying the rear support legs of the cart shown in  FIG. 8D . Handle  138  (shown in  FIG. 9 ) is slid forward, causing rear support legs  140  to rotate forward and downward about axis  142 .  FIG. 10F  schematically illustrates the cart shown in  FIG. 10E  with all support legs deployed. Chassis  112  is supported by front support legs  144  and rear support legs  140 . At this point, rear cart legs  116  may be retracted. Handle  120  is pulled vertically upward, causing front cart legs  116  to extend vertically above axis  119 .  FIG. 10G  schematically illustrates the cart shown in  FIG. 10F  with rear legs retracted. Handle  120  is now rotated about axis  119  toward the front of cart  110  until front cart legs  116  are folded horizontally along the outside of side walls  122  (shown in  FIG. 9 ).  FIG. 10H  schematically illustrates the cart shown in  FIG. 10G  with horizontally folded retracted rear legs. 
         [0085]    Chassis  112  may now be pushed forward into trunk  50  on front casters  132  and rear casters  134  until chassis  112  is entirely inside trunk  50 . In order improve the stability of chassis  112  when the vehicle is in motion, the support legs are retracted.  FIG. 10I  schematically illustrates retracting the support legs of the cart shown in  FIG. 10H . In order to retract front support legs  144  and rear support legs  140 , handles  136  and  138  are slid back toward the rear end of chassis  112 . Sliding handles  136  and  138  toward the rear end of chassis  112 , causes front support legs  144  and rear support legs  140  to rotate upward and toward the rear of chassis  112  (counterclockwise in  FIG. 10H ). As front support legs  144  and rear support legs  140  rotate, chassis  112  descends. Chassis  112  descends until front support legs  144  and rear support legs  140  rotate are fully retracted. Handle  118  may also be folded upward and rearward over chassis  112 , reducing the amount of space occupied by collapsed cart  110 .  FIG. 10J  schematically illustrates the cart shown in  FIG. 10I  with support legs retracted. At this point, chassis bottom  124  of chassis  112  is resting stably on trunk floor  54 . The cover of trunk  50  may now be closed. 
         [0086]    It will be clear to a person skilled in the art, that many variations of the embodiments described are possible. In particular, elements of the various embodiments may be combined. For example, a mechanism that was described in connection with one embodiment may be employed to deploy the front support legs, while a mechanism that was described in connection with a different embodiment may be employed to deploy the rear support legs. Such combinations of elements of various embodiments shall be considered as falling within the scope of the present invention. 
         [0087]    It should be clear that the description of the embodiments and attached Figures set forth in this specification serves only for a better understanding of the invention, without limiting its scope. 
         [0088]    It should also be clear that a person skilled in the art, after reading the present specification could make adjustments or amendments to the attached Figures and above described embodiments that would still be covered by the present invention.