BACKGROUND OF THE INVENTION  
       [0001]     1. Technical Field of the Invention  
         [0002]     The present invention relates generally to wheeled carts useful for the transport of children and/or other cargo. More specifically, provided herein are wheeled carts having a steerable member that permits user-controlled movement of the front wheel and hence steering while retaining contact of all three wheels with the walking or running surface. Wheeled carts disclosed herein are suitable for use by the user while walking or running and simultaneously transporting a child and/or other cargo, provide a roll-cage for protection of the child and/or cargo in the event or a roll-over accident, and are advantageously adapted for folding and ease of transport when not in use.  
         [0003]     2. Description of the Related Art  
         [0004]     Various designs of wheeled carts known in the art can be utilized by the user to transport children and/or other cargo, for example, while the user is jogging or running. These wheeled carts are typically configured with three wheels, a frame assembly, and one or two seats and/or storage compartments. Some of these wheeled carts are configured for folding, disassembly, or a combination of both, thus providing for convenience and versatility in transportation and storage.  
         [0005]     U.S. Pat. No. 6,533,310 describes a collapsible three-wheeled stroller for transporting a child that includes a frame movable between folded and unfolded conditions, a handle mounted on an upper portion of the frame for pushing the stroller, one front wheel and two rear wheels rotatably mounted on a lower portion of the frame, and a seat on the frame for supporting a child. The frame is constructed from a plurality of articulated frame members movable from the unfolded condition to the folded condition with accompanying motion of the rear wheels toward one another and a generally forward and downward motion of the handle.  
         [0006]     U.S. Pat. No. 6,196,572 describes a convertible trailer and stroller having a pair of frame blocks mounted to a frame member, each proximate the two rear wheels of the jogging stroller. The frame blocks are each attached to a wheel block at a wheel pivot that interconnects the frame blocks to their respective wheel blocks. A pair of wheels having hub axle ends is received into a wheel bearing within each of the wheel blocks, and the wheel blocks are rotatable about the respective block pivots to selectably raise or lower each wheel relative to the block pivots. In the lowered wheel or stroller configuration, a high ground clearance for all terrain operation is provided, while in the raised wheel or trailer configuration, a low and stable center of gravity is provided. The convertible trailer and stroller can also include an upper bar that attaches to the wheel blocks. The upper bar converts from a handle bar position to a roll bar position as functions of the pivotable rotations of the wheel blocks about the frame blocks. The handle bar position provides a push or pull point in the stroller configuration, while the roll bar position operates in the trailer configuration to provide protection to a passenger in a tip over.  
         [0007]     U.S. Pat. No. 6,722,689 describes a jogging stroller for carrying a baby that includes three wheels mounted on a frame that holds a cloth seat and includes frame rails that project upwardly and rearwardly from a single front wheel to a horizontal handlebar member at the rear of the stroller. A pair of handles are attached to the handlebar members by a clamp and these include a stem member that extends outwardly from the stroller handlebar and are connected to a perpendicular handle element that can rotate about the stem member and the stem members can be rotated about the axis of the horizontal stroller handlebar and can be slid along the handlebar. The handle elements can be fixed in space in a position desired by the user or can be left loose enough to rotate during use. The handle elements have a coil spring inside a grip member, allowing the handles to flex as the user jogs, thereby permitting more natural motion of the hands and shoulders during jogging.  
         [0008]     U.S. Pat. No. 6,779,804 describes a jogging stroller in which a control block is coupled to the front fork and pivoted with the front fork to the front side of the front frame tube of the stroller frame. An operation rod is provided in the control block and selectively shifted between a first position wherein the control block and the front fork are unlocked for a swivel motion relative to the front frame tube of the stroller frame, and a second position wherein the control block and the front fork are locked and prohibited from swiveling relative to the front frame tube of the stroller frame.  
         [0009]     U.S. Pat. No. 6,830,260 describes a foldable three-wheeled jogging stroller having a lower frame assembly including an axle for supporting two rear wheels, the axle having a pivotally coupled fork assembly to support a front wheel and a pair of fixedly attached upright support tubular members. An upper frame assembly includes a U-shaped handlebar having first and second extension tubular members each fixedly attached to an interconnect member, each interconnect member configured for hinged attachment of an upright support member and for slidably receiving a first end of one of third and fourth tubular members whereby the interconnect member can slide freely along its respective tube to enable an erect upper frame assembly to fold into a collapsed position overlaying the base assembly. The other ends of the third and fourth tubular members are attached to a footrest that further has extension tubular members coupled to the front wheel support.  
         [0010]     U.S. Pat. No. 6,863,297 describes a fold flat walking or jogging stroller, which includes at least three wheels, all having pivoting wheel support units. The wheel support units include, in various embodiments, simple manually manipulable methods to latch each wheel in the operative or stowed flat positions, which effectively allows the device to fold to a flat profile without any wheel being detached. Associated features include a pivoting or floating transverse axle replicating unit, which pivots and latches to replicate a typical fixed wheel axle, but pivots to a fold flat stowed position. The features may also be applied to other types of wheeled carrier devices such as gurneys, golf bag carriers, and hunting game carners.  
         [0011]     U.S. Pat. No. 4,432,561 describes an amusement tricycle wherein the operator is transported in an inclined position on a hammock cradle. The cradle is carried by a front wheel that does not pivot relative to the cradle. Instead, the cradle and wheel rotate about a downwardly sloping axis to turn. The cradle is supported to the rear by a two wheel buggy. The cradle is mounted on the buggy by a pivot. The pivot rotates about its axis. The buggy in turn, is stabilized by pivotable attachment to the cradle.  
         [0012]     U.S. Pat. No. 4,572,535 describes a three-wheeled vehicle having a front body member carrying the front wheel and seat, pivotally connected to a rear body member carrying the rear wheels and handlebar. The pivotable connection is designed to pivot the front body member around a pivotal axis that is projected upwardly and rearwardly at a location rearward of the front wheel whereby pivoting produces sideward and rearward tilting of the front wheel and opposite turning of the rear wheels. Steering is achieved by such pivoting of the front body member that, in turn, is achieved by a sideward swinging of the seat that is positioned between the two pivotable connections. The rear wheels are canted to provide increased stability for the vehicle as it is maneuvered through a turn.  
         [0013]     U.S. Pat. No. 5,354,084 describes a three-wheeled vehicle having a front body member carrying a front wheel seat, hand pedals and leg supports pivotally connected to a rear body member carrying the rear wheels and handlebar. The front body member includes a seat for the operator and pedals to be operated by the rider&#39;s hands. The seat, pedals, front wheel and leg supports are maintained in a fixed relationship whereby pivoting of the front frame portion simultaneously pivots the seat, pedals, drive line, and front wheel to maintain a fixed relationship while turning and supplying power to the front wheel. A stabilizing dampener between front and rear frame sections provides smooth steering and inhibits undesired, inadvertent, side to side movement of the rider&#39;s body and thereby repetitive back and forth turning of the vehicle.  
         [0014]     U.S. Pat. No. 4,789,173 describes a three-wheel vehicle having front and rear frame sections supporting a single front wheel and a pair of rear wheels, respectively. The frame sections are pivotally interconnected about an inclined axis defined by a front lower and rear upper pivotable connection. The upper pivotable connection is provided on a swivel bar which is pivotally connected to the rear frame section for swivel pivoting of the pivotable connection defining the inclined axis. A seat on the front frame section positioned substantially above the swiveled pivotable connection is shifted from side-to-side with the pivoting of the swivel bar and inclined axis. A handle from the swivel bar enables a rider to control the swivel bar for shifting of the rider&#39;s weight and increased or decreased articulation of the vehicle frame and thus turning of the vehicle to thereby increase or decrease the turning that is induced by pivoting of the front frame section about the inclined axis.  
         [0015]     The strollers and three-wheel vehicles described above remain limited in the area of steering, frame assembly design, and optimum folding characteristics.  
       SUMMARY OF THE INVENTION  
       [0016]     Thus, it is an object of the present invention to provide a system to overcome the aforementioned disadvantages and problems. The present invention provides within certain embodiments, wheeled carts that allow controlled steering and turning motion of the wheeled cart while all wheels retain contact with the ground surface.  
         [0017]     In one embodiment, the steering feature of the inventive wheeled cart is defined by the combination of an upper frame assembly that is pivotally connected to a lower frame assembly at a steering assembly in front and a guiding assembly in the rear. The upper frame assembly includes a steering post that is connected to the steering assembly of the lower frame assembly. The upper frame assembly includes a guiding arced tube that is releasably connected to a guiding assembly of the lower frame assembly by a releasable latch.  
         [0018]     The upper frame assembly includes a front wheel assembly and a plurality of tubular members, which include a guiding arced tube, upright struts, main seat tubes, axial tubes and members, and a steering post, fixedly, releasably or insertably connected to one another. Collectively, the combination of tubular members creates a cage in which a rider and/or cargo is protected from contact with the ground in the event of a roll-over accident.  
         [0019]     The lower frame assembly includes at least two rear wheels and tire assemblies and a plurality of tubular members attached forwardly at a steering assembly. The lower frame assembly is further provided with a guiding assembly that is pivotally connected to a pair of the rear tubular members of the lower frame assembly. The guiding assembly is provided with a guiding channel, which receives and releasably engages a guiding arced tube of the upper frame assembly by way of a releasable latch. The guiding arced tube, when engaged, is slidably movable within the guiding channel.  
         [0020]     The steering action of the wheeled cart is controlled by the pivoting movement of the upper frame assembly about the inclined pivotal axis of the steering post through the steering assembly. This pivotal axis of steering typically approximates 45° inclined axis relative to the ground surface. Pivoting of the upper frame assembly in relation to the lower frame assembly causes a relative turning and tilting action of the upper frame assembly including the front wheel assembly. This tilting and turning of the front wheel assembly produces a steering movement of the embodiment of the inventive cart when in motion. Pivoting of the upper frame assembly in relation to the lower frame assembly is controlled and restricted, in part, by movement of the guiding arced tube within the guiding channel of the guiding assembly.  
         [0021]     The steering movement of the presently described wheeled cart is controllable by the user through clockwise or anticlockwise movement of a handle member, optionally connected adjustably to the upper frame assembly. For example, when the user twists the handle member towards the right, it causes the upper frame assembly to pivot in a clockwise motion around the axis of steering thereby tilting and turning the front wheel assembly toward the right while simultaneously causing the guiding arced tube to slide towards the left within the guiding channel.  
         [0022]     Within certain embodiments, the inventive wheeled cart is capable of being re-positioned from a fully-open configuration for use to a fully-folded configuration for storage and transport. The folding action is initiated by pushing down on the upper side of the releasable latch of the guiding assembly thereby releasing the arced tubular member from an opening in the guiding channel. The inventive wheeled cart will begin to fold as the user lifts and directs the upper frame assembly towards front wheel and tire assembly. With the releasable latch in such an open position, the upper rear axial tube, of the upper frame assembly, is lifted, thereby causing the guiding arced tubular member to be lifted up and away from the guiding assembly. Further lifting of the upper rear axial tube causes the rear wheel assemblies to rotate forward and down followed by the attached guiding assembly. A gentle forward pressure on the guiding assembly pushes the wheels further forward into alignment alongside the front wheel. With continued forward lifting, and lowering, the upper frame assembly is moved forward and downward toward the front wheel and tire assembly until the upper frame assembly comes to a stop at a front portion of the front wheel and tire assembly. In a fully-folded configuration, the front and rear wheel and tire assemblies are in parallel juxtaposition, which, collectively, are positioned within the folded frame assembly. The handle member may be released, thereby permitting folding onto the folded frame assembly to achieve a fully-folded configuration suitable for storage and transport.  
         [0023]     These and other aspects of the present invention will become apparent upon reference to the following detailed description and attached drawings. All references disclosed herein are hereby incorporated by reference in their entirety as if each was incorporated individually.  
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0024]     The present invention will be described in greater detail in the following detailed description, with reference to the accompanying drawings, wherein:  
         [0025]      FIG. 1A  shows a side view of a steerable wheeled cart and  FIG. 1B  shows an exploded side view of the steerable wheeled cart of  FIG. 1A ;  
         [0026]      FIG. 2A  shows a front view of the steerable wheeled cart of  FIG. 1A  and  FIG. 2B  shows an exploded front view of the steerable wheeled cart of  FIG. 2A ;  
         [0027]      FIG. 3  shows a rear view of the steerable wheeled cart of  FIG. 1A ;  
         [0028]      FIG. 4A  shows the steerable wheeled cart in an un-turned, straight-ahead configuration;  FIG. 4B  shows the steerable wheeled cart in a right-turned configuration;  
         [0029]      FIG. 5  shows a perspective view of an exemplary steering assembly of a steerable wheeled cart of the present invention;  
         [0030]      FIG. 6A  shows a perspective view of an exemplary guiding assembly of a steerable wheeled cart of the present invention;  
         [0031]      FIG. 6B  shows another perspective view of an exemplary guiding assembly of a steerable wheeled cart of the present invention;  
         [0032]      FIG. 7A  shows a cross-sectional side view of the exemplary guiding assembly of  FIG. 6A  in a fully-engaged configuration;  
         [0033]      FIG. 7B  shows a cross-sectional side view of the exemplary guiding assembly of  FIG. 6A  in a fully-released configuration;  
         [0034]      FIG. 8  shows a side view of the steerable wheeled cart of  FIG. 1A  in a fully-collapsed operational position; and  
         [0035]      FIG. 9  shows a perspective view of the steerable wheeled cart of  FIG. 1A  in a fully-opened operational position. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0036]     Referring to  FIGS. 1A, 1B  and  2 B, an embodiment of wheeled cart  20  comprises an upper frame assembly  22  and a lower frame assembly  24 .  
         [0037]     When introducing elements of the present invention or the preferred embodiment(s) thereof, the articles “a”, “an” “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.  
         [0038]     Upper frame assembly  22  comprises front fork assembly  39  which includes front wheel assembly  30 . Upper aspect of fork assembly  39  is connected to lower end of steering post  86  and lower end of support post  34 . Upper end of post  34  is connected to upper aspect of steering post  86 . Upper aspect of steering post.  86  is connected to axial mid frame member  40 . Left and right main arched seat tubes  32  are fixedly held apart at their lower ends by connection to lateral ends of mid frame member  40 . Seat tubes extend upward and rearward in a generally arced manner. Upper ends of seat tubes  32  are connected to, and fixedly held apart by upper axial tube  46 , and pivotally connected to handle tube  56  and upper ends of left and right upright seat struts  52 . Seat struts  52  are fixedly attached at their lower ends to left and right ends of guiding arced tube  58 .  
         [0039]     Lower frame assembly  24  comprises left and right rear arm assemblies  60  (including rear wheels  70 ), pivotally attached to steering assembly  80  anteriorly. In their open functional position the two rear arm assemblies  60  diverge from front to back to support the rear wheels  70  laterally spaced (see  FIG. 4A ). Rearward aspect of arm assemblies  60  are pivotally attached to lower ends of left and right rear support struts  72 . Upper ends of struts  72  converge medially and are pivotally attached to guiding assembly  90  at its rearward aspect (see  FIGS. 3 and 4 A). Forward aspect of assembly  90  is fixedly attached to the rearward ends of left and right parallel support arms  76 . Forward ends of support arms  76  are pivotally attached to steering assembly  80  at interconnect bracket  78 . Support arms  76  are allowed to pivot downward and forward from approximate horizontal rearward position when open to approximate parallel position with pivotal axis  200  of steering assembly  80 .  
         [0040]     Upper frame assembly  22  is pivotally connected to lower frame assembly  24  anteriorly by steering post  86  within steering assembly  80 . Additionally, when fully open in its functional condition, upper frame assembly  22  is releasably pivotally connected to lower frame assembly  24  posteriorly by arced tube  58  in guiding assembly  90 . Thus, wheeled cart  20  comprises upper frame assembly  22 , which supports a flexible child seat  124  (see  FIG. 9 ), and a child (not shown), pivotally above lower frame assembly  24 .  
         [0041]     Referring to  FIGS. 1A, 1B , and  5 , upper frame assembly  22  comprises front wheel and tire assembly  30  releasably rotatably attached (by conventional methods) to first ends of left and right front fork members  26 . Front wheel assembly  30  of this embodiment is a conventional spoked wheel typically measuring between about 9 and about 24 inches in diameter and optionally having a pneumatic tire mounted thereon. It is contemplated that other types of tires may be used, such as molded urethane foam, or solid tires. Front fork members  26  are held in fixed parallel juxtaposition by insertion, at their respective second ends, into left and right apertures  33  of front fork connector  28  and are fixedly attached to connector  28 . A conventional caliper brake assembly  31  is optionally located between and below front forks anteriorly to connector  28 . Bracket  29  is mechanically fixedly attached to the lower surface of fork connector  28 . Front fork assembly  39  comprises front wheel assembly  30 , front forks  26 , brake assembly  31 , fork connector  28 , and its attached bracket  29 . Front fork assembly  39  is axially pivotally connected to the lower end of steering post  86  by pivot pin  27  through bracket  29  and bushings (not shown) abutting lower end of steering post  86  within the bracket  29 . Unless otherwise noted in the continuing descriptions below, pivot pins (such as  27  above) may be rivets, shoulder bolts or other suitable fasteners.  
         [0042]     Referring to  FIGS. 2A and 5 , upper end of steering post  86  comprises a gooseneck  87  (typical of bicycle handlebar stems) with axial tubular member  88  protruding proximally. Vertical flange  35  fixedly extends downward and proximally from tubular member  88 . Upper end of tubular post member  34  is pivotally attached to flange  35  by axially mounted pivot pin  37 . Lower end of post  34  is flexibly attached to the upper surface of front fork connector  28  at ball and socket joint  38 . Further, post  34 , optionally, comprises shock absorbing member  36  such that, in combination, the distance between the upper pivot pin  37  and the lower ball joint  38  can vary as the shock absorbing member  36  compresses. Compression of the spring in shock member  36  is permitted by axial pivoting between steering post  86  and front fork assembly  39  at pivot pin  27 , as well as some pivoting at connections at both ends of post  34 . It is to be understood that attachments to post  34  can be other suitable connections used in conjunction with other contemplated configurations of the post. In addition, other configurations of the front fork assembly  39  are contemplated such as standard unsprung bicycle front forks.  
         [0043]     Referring to  FIG. 2A , tubular member  88  of gooseneck  87  of upper steering post  86  is connected to axial mid frame member  40 . Mid frame member  40  comprises outer tubular member  42  and inner tubular member  44 . Outer tubular member  42  passes through, and is mechanically fixedly attached at its center, to tubular member  88 . Inner tubular member  44  passes through outer tubular member  42  with clearance between outer and inner diameters, respectively, permitting outer tubular member  42  to act as a supportive bushing or cylindrical sleeve. Pivotal rotation of inner tubular member  44  is allowed around the axis of mid frame member  40 . Inner tubular member  44  is mechanically restricted from lateral motion within outer tubular member  42  by left and right stops  43  fixedly attached to inner tubular member  44 . Left and right ends of inner tubular member  44  are fixedly attached to left and right L-shaped tubular connectors  45 . Connectors  45  are variations on common tube connectors. Connectors  45  may be made of plastic or other suitable material readily available to those skilled in the art. Connectors  45  are mechanically releasably attached to left and right main seat tubes  32  by conventional spring pins (not shown) located inside the ends of seat tubes  32 . Releasable attachment facilitates frame assembly and removal of fabric seat  124  (see  FIG. 9 ) for cleaning. It is to be noted that other connectors can be used or direct attachment, such as by welding, within the scope of the invention.  
         [0044]     Attachment of the main seat tubes  32  (and their associated upper frame structures to be described below) to the pivotal inner tubular member  44  thus allows folding of the upper frame assembly  22  about the axis of mid frame member  40  within inner tubular member  44 . This folding portion may be otherwise constructed within the scope of this invention.  
         [0045]     Referring to  FIGS. 1B and 2B , main seat tubes  32  are generally arched upward and backward (also perspective  FIG. 9 ). Upper rearward ends of seat tubes  32  pass through, and are fixedly attached to, upper left and right L-shaped tubular connectors  47 . Left and right ends of upper axial frame tube  46  are inserted into connectors  47  and releasably attached by conventional spring pins (not shown) located inside left and right ends of axial tube  46 . Connectors other than discussed may be used within the scope of the invention. Upper axial frame tube  46  is parallel to axial mid frame tube  40 . Upper tube  46  and mid frame tube  40  maintain right and left main seat tubes  32  in juxtaposition.  
         [0046]     Rearward of connectors  47 , the ends of main seat tubes  32  insert into, and are fixedly attached to, left and right handle adjustment assemblies  48 . Adjustment assemblies  48  comprise seat tube connectors  49 , upright strut connectors  50 , adjustable rotatable knobs  55 , and handle tube connectors  51 . Left and right ends of handle  56  are inserted into, and fixedly attached to, corresponding handle tube connectors  51  of handle adjustment assembly  48 . Handle tube connecters  51  and seat tube connectors  49  of adjustment assembly  48  are rotatably adjustably attached at the axis of adjustable rotatable knobs  55 . Axially co-facing surfaces of connectors  49  and  51  are equipped with interlocking radial teeth (not shown) that are released or engaged by adjustable knobs  55 . Release or engagement of the teeth (not shown) allows handle bar  56  to be folded for compact storage and transport, or adjusted in height to individual comfort for use (see  FIGS. 1A and 8 ). This radial teeth rotational adjustment is commonly known in the industry. It is noted that other types of handle adjustment are contemplated within the scope of the invention.  
         [0047]     Referring to  FIG. 1B , left and right upright rear seat struts  52  axially pivotally attach at their upper ends to strut connectors  50  by pivot pins  54 . Lower ends of seat struts  52  pass through and are fixedly attached to left and right ends of guiding arced tube  58 . Orientation of arced tube  58  in the open, in use position, is such that it approximates an arc, of an imaginary circle  210 , perpendicularly centered on steering axis  200  (see  FIGS. 1A, 4A , and  4 B). Upper connections of seat struts  52  at pins  54  allow arced tube  58  and struts  52  to rotate toward main seat tubes  32 , facilitating compact folding in this favored embodiment. Rearward motion of seat struts  52  and arced tube  58  is constrained by underseat folding plastic membrane  120  (see  FIG. 6A ). Membrane  120  is attached by rivets (four shown), or other suitable fasteners, to arced tube  58  and in front at inner tubular member  44  of axial mid frame assembly  40  (attachment not shown). Membrane  120  cushions rider from elements of steering assembly  80  and provides a low friction surface for motion of seat  124  over these elements during rotational motion of steering of cart embodiment  20 . It is to be appreciated that the joined frame elements may be attached by connections other than discussed. It is further contemplated that conjoined elements can otherwise consist of a single bent contiguous section of tubing or other structure within the scope of the invention.  
         [0048]     Referring to  FIGS. 1B and 2B , lower frame assembly  24  comprises left and right rear wheel and tire assemblies  70  releasably rotatably mounted to left and right rear arm connectors  62  by conventional releasable axle pins (not shown) readily available to those skilled in the art. The rear wheels of this embodiment are conventional spoked wheels measuring about  9  to about  24  inches in diameter and, optionally, having a pneumatic tire mounted thereon. It is contemplated that other types of tires may be used, such as molded urethane foam, or solid tires. Rear arm connectors  62  are pivotally connected at rear ends of left and right sets of equal length parallel rear arms  66 A and  66 B by pivot pins  64 . Forward ends of these parallel rear arms  66 A and  66 B are pivotally connected to left and right forward arm connectors  68  (at steering assembly  80 ) by pivot pins  64 . Each rear arm assembly  60  comprises rear wheel assembly  70 , rear connectors  62 , arms  66 A and  66 B, forward connectors  68  and corresponding connecting pins  64 . Forward arm connectors  68  in conjunction with rear arm connectors  62  maintain parallel juxtaposition of arms  66 A and  66 B throughout the range of motion allowed by spacing of pivots defined by pins  64 . Forward arm connectors  68  are fixedly attached to left and right connecting plates  84  which are fixedly attached to outer sleeve  82  of steering assembly  80 . Connecting plates  84  are oriented such that forward arm connectors  68  are angled downward and inward in relation to steering assembly  80 . This orientation is such that, rear arm assemblies  60  rotate downward, forward, and inward, during folding. Rear wheels  70  are maintained in a parallel orientation on their respective left and right sides as they approach medially. Suitable wheel folding technologies are readily available to those skilled in the art. It is contemplated that two or more attached elements described above may be made as one, or alternative rear arm assemblies may be used within the scope of the invention, such as, for example, having a single arm element per side, or assemblies with fixed rear wheel width.  
         [0049]     Referring to  FIGS. 3, 4A , and  4 B, lower frame assembly  24  further comprises left and right rear support struts  72  that are connected at  65  to rearward aspects of left and right arms  66 A. Connection  65  comprises a U-shaped clevis  69  rotatably mounted on arm  66 A by a rivet (not shown) or other suitable fastener. Lower end of support strut  72  is pivotally mounted inside the clevis  69  by pivot pin  67 . Connection  65  thus allows supports  72  to rotate and pivot in relation to struts  66 A during folding or movement of rear arm assemblies  60 .  
         [0050]     Referring to  FIGS. 6A and 6B , upper ends of support struts  72  converge medially to connect pivotally to flanges  77  by pivot pins  73  at left and right rear elements  92  of guiding assembly  90 . Flange  77  is rotatably connected to rear element  92  by shaft (not visible) to end fastener  71 . Rotatable flanges  77  thereby form a multi-axis connection  75  with struts  72 . Multi-axis connections  75  permit supports  72  to pivot forward and medially during folding and rearward and laterally during unfolding of the rear arm assemblies  60 . Support struts  72  further comprise shock absorbing members  74 , exemplified by a coil spring. Shock members  74  allow limited independent left and right vertical motion of the rear arm assemblies  60 . Thus, by this embodiment, rear arm assemblies  60  provide cushioning for both the rider and user during travel of the cart over uneven surfaces. It is to be understood that other configurations of struts  72  and their connections are contemplated within the scope of this invention, including coincidental attachment of the struts to an intermediate member.  
         [0051]     Referring to  FIGS. 1B, 4A ,  4 B,  6 A, and  6 B, lower frame assembly  24  further comprises a guiding assembly  90  that is pivotally connected to steering assembly  80  by parallel support arms  76 . Rearward ends of arms  76  are inserted into left and right parallel apertures  91  in guiding assembly  90 , and fixedly attached to this assembly. Forward ends of arms  76  are axially pivotally attached to interconnect bracket  78  which is fixedly attached to the upper posterior aspect of outer sleeve  82  of steering assembly  80 . Support arms  76  and guiding assembly  90  are allowed to rotate around axis of pin  79  downward and forwardly during folding, and rearward and upwardly during unfolding of the rear arm assemblies  60 . Upward travel of parallel support arms  76  is limited to approximately horizontal by interconnect bracket  78 . Other configurations of arms and connections are contemplated without departing from the scope of the invention.  
         [0052]     Referring to  FIGS. 6A, 6B ,  7 A, and  7 B, guiding assembly  90  comprises rear elements  92  with upward protrusions  94  with or without rollers  96  as seen in  FIGS. 6A and 6B . Centered between these rear elements  92  is latch  110  rotatably mounted on axial shaft (not visible) affixed between left and right rear elements  92 . Hidden shaft is surrounded by rotationally tortioned spring  108  which holds latch  110  in its forward most rotated position against latch post  106 . Latch  110  comprises curved neck  104 , forward projecting beak  102  and rearward projecting release tab  100 .  
         [0053]     Referring to  FIG. 6B and 7A , lateral upward protrusions  94  and latch neck  104  comprise the rear elements of a guiding channel  95  into which arced tube  58  of upper frame assembly  22  is releasably attached in the open configuration of cart embodiment  20 . Forward elements of guiding channel  95  comprise centrally located latch post  106  and laterally situated low friction rollers  96 . Rollers  96  are rotatably attached in approximately axial relationship to pivotal axis  200  of steering assembly  80  by pivot pins  97  through retaining flange  98 . Flanges  98  are affixed to body of guiding assembly  90  by screws (three are shown) or other suitable fasteners. The lower bounds of guiding channel  95  comprise low friction bushings  99  located laterally between the forward rollers  96  and the upward protrusions  94  to the rear. Upper bound of the guiding channel  95  is the undersurface of latch beak  102 . It is to be understood that positioning and orientation of guiding channel elements may be other than described without departing from the scope of the invention Referring to  FIG. 5 , lower frame assembly further comprises steering assembly  80 , which is made up of outer sleeve  82 , affixed left and right connecting plates  84  (which attach left and right forward strut connectors  68 ), and affixed interconnect bracket  78  in the upper rear aspect (which pivotally attaches parallel support arms  76  to which guiding assembly  90  is attached). Steering assembly  80  thus connects all forward projecting elements of the lower frame assembly  24  and holds them in relation to each other relative to the upper frame assembly  22  which pivots within the steering assembly on its steering post  86 . The steering assembly may be otherwise constructed within the scope of this invention.  
         [0054]     Referring to  FIGS. 1A, 1B , and  5 , the upper frame assembly  22  is fixedly pivotally connected to lower frame assembly  24  anteriorly at its steering post  86  within lower frame steering assembly  80 . Steering post  86  pivots within standard rotary elements (not shown) inside outer sleeve  82  of steering assembly  80 . It is contemplated that upper and lower frame assemblies may be pivotally attached by ways other than shown such as by a flexible member connecting along, and bending at, the steering axis without departing from the scope of the invention.  
         [0055]     Referring to  FIGS. 6A, 7A , and  7 B, upper frame assembly  22  is releasably attached to lower frame assembly  24  posteriorly by arced tube  58  in guiding channel  95 . Arced tube  58  is constrained within guiding channel  95  in its rearward motion by the upward projections  94  lateral to latch  110  and cannot push latch  110  open rearwardly. Forward motion of arced tube  58  within guiding channel  95  is constrained by roller elements  96  laterally and latch post  106  medially. Upward motion of arched tube  58  within guiding channel  95  is constrained by the underside of curved beak  104  of latch  110  unless the latch is opened prior to such upward motion. Release of arced tube  58  from guiding channel  95  is effected by manual action (inclusive of foot) to open latch  110  against torsional rotational spring  120  and subsequent lifting of arced tube  58  from channel  95 . Latch  110  is configured such that it effectively traps arced tube  58  when arced tube  58  is lifted without active opening of latch  110  by release tab  100 .  
         [0056]     Referring to  FIGS. 7A , and  7 B, engaging arced tube  58  into guiding channel  95  entails pushing arced tube  58  downward against the rearward surface of latch post  106  so that arced tube  58  contacts the upper surface of curved beak  104  of latch  110 . Downward pressure of arced tube  58  against the top of latch beak  104  causes latch  110  to rotate rearward against tortional rotational spring  120  thereby opening latch  110  and allowing arced tube  58  to drop into guiding channel  95 . Latch  110  closes over arced tube  58  automatically by force of rotational spring  120 . Note that other latching devices are contemplated within the scope of this invention.  
         [0057]     Referring to  FIGS. 4A, 4B ,  6 A, and  6 B, arced tube  58  is allowed to rotate along an arc of imaginary circle  210  within the guiding channel  95 . Rollers  96 , low friction surfaces  99 , and clearance between arced tube  58  and guiding channel elements facilitate this motion. Lateral rotational motion of arced tube  58  is restricted by left and right protrusions  53  at its ends. These protrusions  53  form rotation limiting stops that encounter the lateral aspects of rear elements  92  of guiding assembly  90  at the extreme of motion of arced tube  58  within guiding channel  95 .  FIGS. 4A and 4B  depict inline and extreme rightward rotation respectively of upper frame assembly  22  in relation to lower frame assembly  24 , from a perspective down the pivotal axis of steering  200 . Rotation limiting stops may be otherwise constructed within the scope of this invention.  
         [0058]     Referring to  FIGS. 1A, 4A  and  4 B, preferred embodiment  20  further comprises upper and lower frame assemblies  22  and  24  in relationship such that the pivotal axis of steering  200  extends down and forward to pass through the lower aspect of front wheel  30 . Steering axis  200  extends up and rearward through seat  124  and passes handle  56  at approximate midline, above or below, depending on handle  56  adjustment. In this preferred embodiment axis  200  passes through the anterior aspect of seat  124  such that upper frame assembly  22  exhibits a self centering effect by gravitational forces with or without a child in the seat  124 . It is to be understood that other pivotal axis of steering may be employed within the scope of the invention.  
         [0059]     Referring to  FIGS. 1A and 9 , it will be appreciated that the favored three wheeled cart embodiment  20  comprises flexible fabric child seat  124  supported by and between arced seat tubes  32 . Seat  124  is also supported in front by mid frame member  40  and in back by upper frame tube  46 . Seat is further supported and protected from below by foldable plastic membrane  120  seen in  FIG. 6 . Restraining harness  114  is attached to seat back  126  and rear side of seat  124 , which is attached (not shown) at its lower corners near the junction of upright seat struts  52  and arced tube  58 . A footrest wheelguard assembly  132  of the embodiment  20  is positioned to protect the child rider from underlying mechanisms and from road debris that may be thrown up from the front tire  30 . Additionally a roll cage like structure is formed by the arched main seat tubes  32  and the upright rear seat struts  52  with the cart in the open operational condition. A further safety feature not shown is a lanyard attached to the junction of seat strut  52  and arced tube  58 , to be worn on the wrist of the jogger user to prevent a runaway cart. The user may also slow or stop the moving cart  20  by operation of the standard caliper brake  31  ( FIG. 5 ) by actuating handbrake lever  122 , favorably positioned on handle  56  ( FIG. 9 ). The mechanism of lever  122  is provided with a lock enabling the user to lock the brake  31  so that the cart  20  is unable to roll unintentionally with a child rider aboard. Additionally, in the unfortunate event of a rollover a child rider, properly affixed in seat  124 , by restraining harness  114  would be protected from an encounter of its head with the ground by the aforementioned roll cage elements.  
         [0060]     Referring to  FIGS. 4A, 4B  and  9 , steering of cart embodiment  20  while in use (not shown with rider in seat  124  being pushed by user who is pushing on handle  56  while running, jogging or walking behind cart) is effected by a gentle tortional rotation of handle  56  clockwise or anticlockwise. Clockwise rotation of handle  56  produces rotation of upper frame assembly  22  (including front fork assembly  39 ) around steering axis  200  in relation to lower frame assembly  24  (see  FIG. 4B , full right rotation). This clockwise rotation causes a turning and tilting motion of front wheel  30  to the right thereby steering the cart  20  to the right while in motion. Anticlockwise motion of handle  56  produces a similar rotation, turning, and tilting of the front wheel  30  to the left, thereby steering the cart  20  to the left while in motion. Notably, steering with embodiment  20  is effected without lifting the front wheel  30  off the ground as with fixed front wheel carts. Also notable is that user has full control of direction of travel unlike carts with a castor front wheel. In addition, preferred embodiment  20  tends to self align by gravitational forces, while at rest or in motion, when upper frame  22  is rotated as with steering. When in motion cart  20  will tend to maintain an inline direction of travel until gentle force rotates the handle  56  and will tend to resume inline travel when the force is relaxed. Child seat  124  also tilts with steering rotation of handle  56  and produces an effect such that outward inertial forces of turning are favorably supported by the bottom of seat  124  as though the rider were supported in a swing.  
         [0061]     Additionally, rider and user are cushioned from transmission of intermittent forces of cart  20  rolling over uneven surfaces by vertical motion of front wheel  30  and rear wheels  70  allowed by shock members  36  and  74  respectively and the favored configurations of front fork assembly  39  and rear arm assemblies  60  in this embodiment  20 . User is also provided with a padded handle  56  in embodiment  20 . Additional optional advantageous features of this embodiment  20  include: adjustable reclining seat back  126  for rider comfort and sleep; sun and rain cover  128  for protection of rider from the elements; underseat cargo bag  130 ; and a beverage holder pouch and a wallet pouch for user located on the rear surface of seat back  126  (not shown).  
         [0062]     Referring to  FIGS. 1A, 4A ,  8 , and  9 , folding of the preferred cart embodiment  20  is accomplished (without child in seat  124 ) by user manually releasing latch  110  by pushing down and back on release tab  100  and subsequently lifting upper axial frame tube  46  thereby lifting arced tube  58  from guiding channel  95 . Higher lifting of tube  46  elevates mid frame member  40  and attached steering post  86  and steering assembly  80  and attached forward arm connectors  68  thereby lifting front ends of rear arm assemblies  60 . Rear wheels  70  swing forward as arm assemblies  60  swing downward, followed by guiding assembly  90  attached to rear support struts  72 . A gentle push forward by user on guiding assembly  90  while continuing to lift upper frame tube  46  facilitates and completes forward motion of rear arm assemblies  60  and rear wheels  70  to their fully folded position adjacent to front fork assembly  39  and front wheel  30 . All three wheels are now in a forward position as upper frame tube  46  is lowered and upper frame assembly  22  pivots forward at mid frame member  40 . As tube  46  is further lowered, steering assembly  80  lowers to the ground and tube  46  is brought forward, over and down to the three wheel assemblies ( 30 , and two  70 s). Seat tubes  32  settle outside of wheels  70  and tube  46  encounters front wheel  30 . Handle  56  is released by use of knobs  55  and rotated to backside of seat struts  52  as seen in  FIG. 8 . Handle  56  and struts  52  may be further pushed down thereby folding underseat plastic membrane  120  (seen in  FIG. 6 , not seen in  FIG. 8 ) to complete the compact folding.  
         [0063]     Unfolding and opening cart embodiment  20  is accomplished by user lifting upper frame tube  46  until rear wheel assemblies  70  are hanging down off steering assembly  80 . A gentle rearward pull on guiding assembly  90  causes the rear arm assemblies  60  to swing rearward via tension on rear support struts  72 . As soon as rear arms  60  are angled outward from steering assembly  80  lowering of tube  46  pushes wheels  70  further out into open position. As upper frame tube  46  is lowered to its final position arced tube  58  is guided to the rear surface of latch post  106 . Gentle downward pressure (or force of gravity) results in arced tube  58  engaging in to guiding channel  95  (described in detail above). Latch  110  automatically closes over tube  58  by force of tortional spring  108 . Handle  56  is then adjusted to preferred height as previously described by use of adjustment knobs  55 .  
         [0064]     In addition to a child rider, the upper and lower frame assemblies  22  and  24  of the wheeled cart  20  could support a variety of items and be used in a variety of applications in areas such as medical, mail and parcel, sports, and the like.  
         [0065]     In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.  
         [0066]     While certain embodiments of the present invention have been described, it will be understood that various changes could be made in the above constructions without departing from the scope of the invention. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
Provided herein is a wheeled cart useful for the transport of children and/or other cargo. The wheeled cart comprises a steerable member that permits user-controlled movement of the front wheel and hence steering while retaining contact of all three wheels with the walking or running surface. Inventive wheeled carts are suitable for use by the user while walking or running and simultaneous transport of a child and/or other cargo, provide a roll-cage for protection of the child and/or cargo in the event or a roll-over accident, and are advantageously adapted for folding and ease of transport when not in use.