Abstract:
A foldable trailer includes a substantially horizontal, substantially planar center section joined to at least one main axle and wheels assembly, at least one substantially planar rear section attached to the center section by a first hinged interface, such that the rear sections may be folded from a substantially horizontal position, coplanar with the center section, to a substantially vertical position relative to the horizontal center section, at least one substantially planar forward section attached to the center section by a second hinged interface, such that the forward sections may be folded from a substantially horizontal position, coplanar with the center section, to a substantially vertical position relative to the horizontal center section, a tongue section attached to an outermost forward section by a third hinged interface, such that the tongue section is enabled to fold downward around the third hinged interface, as the forward sections are folded, resulting in both the tongue section and the forward sections being oriented to a substantially vertical position relative to the center section, and a forward and a rear set of trolley legs, each set having trolley wheels. As the forward and rear sections are folded upward, the sets of trolley legs are deployed downward, lifting the folded trailer on the trolley wheels with the main axle and wheels assembly off ground level, such that the folded trailer may be moved about on the trolley wheels without interference from the main axle and wheels assembly.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to vehicle-towed trailers and more particularly to trailers that are capable of being folded to occupy a reduced space. 
     2. Description of Related Art 
     Trailers are common to those having a need to transport various items such as motorcycles, recreation vehicles of various size and function, building materials, lawn equipment and watercraft for example. Trailers provide numerous advantages such as, but not limited to, creating additional space for the purpose of cargo transport, that would not easily be accommodated in the carrying capacity of commonly used vehicles, such as small to medium sized SUVs&#39; and passenger cars, which have limited cargo area. A trailer may also be detached from the vehicle and placed into storage when not in use, allowing a more compact and efficient design of the towing vehicle. 
     A drawback to trailers is that they consist of one or more axles, a tongue section and typically a rectangular frame structure with decking, and the sections are generally permanently affixed together, making them notably rigid in design. Another drawback is the stowage of this rigid design, requiring a significant area to accommodate the trailer&#39;s size. Furthermore, it is often unacceptable in neighborhood covenants to store trailers in open view, forcing the owner to provide on-site storage facilities that require maintenance and expense, or off-site storage, that may not always be economical. Attempts have been made in the prior art to overcome the problematic storage and rigid design of trailers by developing collapsible or foldable designs that occupy smaller space. However, the folding trailers in prior art are not of a design sufficient to accommodate loads of considerable mass or volume. Other prior art trailers show designs of difficult operation, often requiring multiple personnel to perform the task of folding the trailer to a storable configuration, or to move the folded trailer to a storage area. Other designs sacrifice the trailer&#39;s load carrying capacity to be more readily folded and maneuvered. 
     Despite the advantages taught in prior art of foldable or collapsible trailers, improvements are still being sought by the general public. Accordingly, what is needed in the art is a foldable trailer that provides increased load carrying capacity but eliminates the need for additional personnel required for the folding operation. In addition, a trolley system that provides stability during the folding operation and ease of maneuverability with a reduced footprint, for the storage of the foldable trailer would be a unique and desirable feature. 
     BRIEF SUMMARY OF THE INVENTION 
     The inventor in the present application has recognized a need for certain features in a foldable trailer that are not provided by trailers in the current art, and has accordingly provided, in one embodiment, a foldable trailer, comprising a substantially horizontal, substantially planar center section joined to at least one main axle and wheels assembly, at least one substantially planar rear section attached to the center section by a first hinged interface, such that the rear sections may be folded from a substantially horizontal position, coplanar with the center section, to a substantially vertical position relative to the horizontal center section, at least one substantially planar forward section attached to the center section by a second hinged interface, such that the forward sections may be folded from a substantially horizontal position, coplanar with the center section, to a substantially vertical position relative to the horizontal center section, a tongue section attached to an outermost forward section by a third hinged interface, such that the tongue section is enabled to fold downward around the third hinged interface, as the forward sections are folded, resulting in both the tongue section and the forward sections being oriented to a substantially vertical position relative to the center section, and a forward and a rear set of trolley legs, each set having trolley wheels. As the forward and rear sections are folded upward, the sets of trolley legs are deployed downward, lifting the folded trailer on the trolley wheels with the main axle and wheels assembly off ground level, such that the folded trailer may be moved about on the trolley wheels without interference from the main axle and wheels assembly. 
     Also in one embodiment the rear sections are folded by a first powered linkage, and the forward sections are folded by a second powered linkage, and further comprising a control interface whereby the powered linkages may be operated to fold and unfold the sections. The power for the powered linkages may be provided by one or a combination of hydraulic or pneumatic motive systems. 
     In one embodiment there is a stabilizer foot deployable from a forward side of the center section to contact ground level. Also, the forward set of trolley lift legs may be deployed with the rear and forward sections locked coplanar with the center section, to tilt the trailer to a backward angle to facilitate loading and unloading cargo. 
     In some embodiments the stabilizer foot is deployed as the rear section is folded upward, to prevent the trailer from moving on the main wheels before the main wheels are lifted from ground level by deployment of the trolley legs. In addition there may be first locking mechanisms arranged to secure the forward, center, rear and tongue sections in a coplanar aspect in which the trailer may be towed for conveying cargo, and second locking mechanisms arranged to secure the forward, center, rear and tongue sections in folded aspect, the locking mechanisms including mechanisms for securing and releasing. 
     In many embodiments of the trailer, with the forward and rear sections arranged coplanar with the center section, and forming a trailer bed, the trailer further comprises removable side panels arranged around the periphery of the trailer bed. The side panels associated with the forward and the rear sections are enabled to be folded onto the center section prior to folding the center and forward sections relative to the center section. 
     In some cases there is a single forward and a single rear section, with the tongue section hinged to the forward section opposite the second hinged interface. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is an isometric view of a foldable trailer in an embodiment of the present invention, shown in the transport position. 
         FIG. 2  is an isometric view of a foldable trailer in an embodiment of the present invention, shown in the folded position. 
         FIG. 3  is a plan view of a foldable trailer of  FIG. 1  and  FIG. 2 , shown in the transport position and illustrates the folding directions of the side and end panels. 
         FIG. 4  is an isometric view of a foldable trailer of  FIG. 1  and  FIG. 2  which further illustrates the folded positions of the side and end panels of  FIG. 3 . 
         FIG. 5  is an elevation view of a foldable trailer of  FIG. 1  and  FIG. 2  shown in the transport position. 
         FIG. 6  is an elevation view of a foldable trailer of  FIG. 1  and  FIG. 2  shown in the folded position. 
         FIG. 7  is an elevation view of a foldable trailer of  FIGS. 1 and 2  shown tilted to allow the loading or unloading of cargo while still attached to a towing vehicle (not shown). 
         FIG. 8   a  is a partial section view of the tongue section and ball hitch receiver lock mechanisms of a foldable trailer of  FIG. 3 . 
         FIG. 8   b  is a partial plan view of the tongue section and ball hitch receiver lock mechanisms of a foldable trailer of  FIG. 8   a.    
         FIG. 9  is an isometric view of a foldable trailer of  FIGS. 1 and 2  showing the essential structural frame elements. 
         FIG. 10  is a partial plan view of the center and rear sections of a foldable trailer of  FIG. 5 . 
         FIG. 11  is a partial section view of the center and rear sections of a foldable trailer of  FIG. 10 , showing the rear deck and center section support leg mechanisms. 
         FIG. 12  is a partial section view of the center and rear sections of a foldable trailer of  FIG. 10 , showing the rear deck section and center section support leg mechanisms, with the rear section lifted to its folded position and the center section support legs deployed. 
         FIG. 13   a  is a block diagram showing the hydraulic and control mechanisms of the foldable trailer of  FIG. 1  and  FIG. 2 . 
         FIG. 13   b  is a detail view showing the control panel of the foldable trailer of  FIG. 1  and  FIG. 2 . 
         FIG. 14   a  is a flowchart diagram that describes the steps required for the detachment from a towing vehicle and the folding, in preparation for storage, of a foldable trailer of  FIG. 1  and  FIG. 2 . 
         FIG. 14   b  is a continuation of the flowchart diagram of  FIG. 14   a.    
         FIG. 14   c  is a continuation of the flowchart diagram of  FIG. 14   b.    
         FIG. 15   a  is a flowchart diagram that describes the steps required for the unfolding and attachment to a towing vehicle, in preparation for transport, of a foldable trailer of  FIG. 1  and  FIG. 2 . 
         FIG. 15   b  is a continuation of the flowchart diagram of  FIG. 15   a.    
         FIG. 15   c  is a continuation of the flowchart diagram of  FIG. 15   b.    
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is an isometric view of a foldable trailer  101  in an embodiment of the present invention. The foldable trailer may be configured to be towed by a number of types of vehicles (not shown). Therefore, trailer  101  is depicted generally in  FIG. 1 , unattached to a towing vehicle, as a “stand-alone” entity. It shall be noted that the foldable trailer of the present invention can be in different sizes and a various number of configurations, within the scope of this disclosure. The foldable trailer of  FIG. 1 , shown in an open or “unfolded” condition, comprises a tongue section  201 , a forward section  301 , a center section  401  and a rear section  501 , all of which proportionately form a cargo carrying platform that is supported by an axle and wheel assembly  404 , which provides transportability to the whole while being towed. Other embodiments of the present invention may include, but not be limited to, multiple axles to vary the load capacity of the foldable trailer, or may be “sled” runners that allow it to be transported across ice and snow surfaces, for example. 
     The foldable trailer of  FIG. 1 , generally having sections  301 ,  401  and  501 , is has three separate rectangular box steel frame structures as illustrated in more detail in figures and description below, joined together by hinge or other acceptable method that allows free rotation. These sections, when combined as a whole, form a horizontal plane parallel to the ground surface, in which a number of different materials may be attached, for the purpose of creating a flat “deck” surface, which supports the cargo and allows it to be transported. The “deck” area may comprise individual planks, or may be large sheets of a variety of weatherproof materials that extend to the edges of the frame structure of each section. In one embodiment of the foldable trailer of  FIG. 1 , large plywood sheets that form elements  305 ,  403 , and  505  are covered with a vinyl weatherproof sheathing, are wrapped on the outer edges with channel steel framing, and are attached directly to the rectangular box steel frame elements  306 ,  409  and  506  with suitable fasteners. 
     The tongue section of the foldable trailer of  FIG. 1  is depicted as being supported by a trailer stand  203 , which may be mounted to tongue section  201  rectangular box steel frame  204 , on a cylindrical mount, in such a way that will accommodate the stand to be rotated about this mount&#39;s axis and locked into place with a release-pin (not shown), such that the stand is perpendicular to the ground surface. The trailer stand may have a swivel caster at its base, or may have any number of other roller or fixed-type bases well known in the art, and can then be lowered to make contact with the ground, providing an element of support and maneuverability. Alternatively, it may be raised and rotated parallel to the ground, while the trailer is in transit. 
     In an embodiment of the present invention, a perimeter wall is formed of various sized panels, held perpendicular to the “deck” surfaces, to contain or protect the cargo which may be transported with the foldable trailer. In an embodiment of the invention the panels are of formed and painted steel, but may be made of any one of a number of different materials, such as aluminum, marine plywood or solid wood planking, for just a few examples. Forward side panels  302 , forward end panels  304 , rear side panels  502  and rear center panels  504  are joined together using any variety of hinge and pin mechanism that allow rotating motion that accommodates the panels to be folded onto the center deck  403  area of the center section  401 , as shown below in  FIG. 4 . In one embodiment of the invention rear end panels  502  may be combined to form one panel that may be attached by hinge or, other acceptable form that allows rotation, to the frame structure of the rear section and may be folded down to the ground, acting in a “tailgate” fashion that allows easy access for rolling stock on and off the cargo platform, for example. The side and end panels, in other embodiments of the invention, may be affixed to the platform area perimeter by upright stanchions or other forms of attachment that allow the panels to be removed and possibly stacked onto the center section, prior to the folding operation. A number of possibilities exist for the panel configuration, the options depending, but not limited to, the type of cargo that may be transported, cost effectiveness or the aesthetic preferences of the user, being many and as varied as the users. 
       FIG. 2  is an isometric view of the foldable trailer of  FIG. 1  shown in a closed or “folded” condition, and free standing on a trolley support system, which allows full mobility for relocation to a storage facility. The foldable trailer of  FIG. 1  and  FIG. 2  are comprised of four sections that are hinged transversely together, with the center section  401  acting as the pivotal section, to which the other sections are folded against. In the unfolded condition these sections form a continuously flat rectangular “deck” area, as shown and described above, where various types of cargo may be placed for transport, such as mulches, aggregates, boxes, lumber or rolling stock, for examples. The forward section  301  and the rear section  501  act independently of one another, and the tongue section  201 , being acted upon by the folding of the forward section, is folded vertically to the center section, to occupy a reduced footprint, as evidenced by the length components of  FIG. 1  and  FIG. 2  respectively. 
     In one embodiment of the invention tongue section  201  is transversely joined to rectangular box steel frame  306  of forward section  301  using any one of a variety of hinge mechanisms that will allow the tongue section to rotate to the underside of the forward section, as the forward section is rotated upwardly to its “folded” state. Rectangular box steel frame  306  of the forward section is transversely joined to a rectangular box steel frame  409  of center section  401  using any one of a variety of hinge mechanisms that will allow the forward section to fold in an upward motion until coming to a near perpendicular position to the decking of the center section. To prevent an “over-rotation” state, towards the direction of rotation to the “folded” state of the forward and rear sections, a variety of “positive-stop” mechanisms (not shown) may be utilized. In one embodiment of the invention, short sections of linkable chains are used with steel plates that are welded to the underside frame structure of both the forward and rear section&#39;s frame structure rails and on the adjacent frame section rails of the center section rectangular box steel frame structure. The chain sections are then attached with bolts on both ends of these chains and connected to each opposing steel plate, with appropriate threaded hardware, allowing an element of fine adjustment. 
     Now, in the opposing direction, towards the direction of the “unfolded” or open state, in one embodiment of the invention the addition of “positive-stop” rails  309  and  509 , of a like material to the rectangular box steel frames to which they are attached, have been utilized. They are attached to the underside exterior rails of the rectangular box steel frame elements  306  and  506  and extend beyond the hinge bearing rail of both the forward and rear sections for some length inwardly, towards the centerline of the foldable trailer&#39;s axle. The uppermost surface of these “stub” positive-stop rails make direct contact to the underside surface of the exterior rails of the center section&#39;s rectangular box frame element  409 , thus preventing rotation beyond a horizontal condition. 
     In one embodiment of the invention, the foldable trailer, when in the “unfolded” or open state, has a forward section  301  and the rear section  501  that are locked into a horizontal position to the center section  401 , preventing their upward movement in transit. The locking mechanisms (not shown) may be any one of a many varied forms, well known to practitioners of the art, to accommodate the immobility or “bounce” effect of the separate sections that make up the foldable trailer&#39;s deck area. It shall be noted here, that prior to the folding of the forward and rear sections to the “storable” state of the foldable trailer of  FIG. 1  and  FIG. 2 , these sections must be unlocked from their horizontal and immobile condition to a “free” and rotatable condition, for the folding operation to occur. 
       FIG. 3  of foldable trailer  101  is a plan view of the foldable trailer of  FIG. 1  and  FIG. 2  that illustrates the motion directions in which the forward end panels  304 , the forward side panels  302 , the rear end panels  504  and the rear side panels are folded onto the center deck  403  area. The forward end panels are folded against the forward side panels, inwardly towards the interior surfaces of the forward side panels, and each of the left side and right side forward side panels are then folded, to a near perpendicular state to the center side panels  402 , of the center deck  409  area of the center section  401 . The rear end panels are folded against the rear side panels, inwardly toward the interior surface of the rear side panels, and each of the left side and right side rear side panels are then folded to a near perpendicular state to the center side panels, of the center deck are of the center section. 
       FIG. 4  is an isometric view of the foldable trailer of  FIG. 1  and  FIG. 2  that further illustrates the folding of the forward end panels  304 , the forward side panels  302  of the forward section  301  and the rear end panels  504 , the rear side panels  502  of the rear section  501  onto the center deck  403  area of the center section  401 , in one embodiment of the present invention. It should be noted that the forward support panel  303  and the rear support panel  503  and the respective center hinge pins (not shown) have been removed prior to the folding operations of the aforementioned panels. 
       FIG. 5  is an elevation view of the foldable trailer of  FIG. 1  and  FIG. 2  that illustrates the “in transit” position of forward trolley lift leg  307  mechanism. In one embodiment of the present invention, the forward trolley lift leg is secured to the underside of the rectangular box steel frame  306  of the forward section  301  using a suitable securing device that may be remotely operated by the user to disengage the forward trolley lift leg from its secured position, for the purpose of operating as a lifting mechanism, and when powered to its secured position, be “locked” into position by a suitable “spring action” of the locking device. The securing device may also be mechanically operated by automation of hydraulics, pneumatics or by other forms of mechanical device, known to those skilled in the art.  FIG. 6  is an elevation view of the foldable trailer of  FIG. 1  and  FIG. 2  in an embodiment of the present invention that further illustrates the “compact” configuration that may be obtained, from the folding of the tongue section  201 , forward and rear sections  301  and  501  of the foldable trailer, to the “stationary” center section  401 . These sections, being joined by transverse hinges, are supported by automated mechanics that deploy at different stages of the “folding” operation, and the foldable trailer is lifted from the ground, elevating the foldable trailer sections, axle and tires. This, in particular, will more readily allow the foldable trailer to be relocated to a storage facility which is supported in its entirety by the forward trolley lift leg  307 , the forward trolley lift leg casters  308 , the rear trolley support legs  512  and the rear support leg casters  513 . In other embodiments, the forward trolley lift leg and the rear trolley support legs may have swiveling casters or other suitable rolling devices which may facilitate the relocation to a storage facility. 
     In one embodiment of the invention of the foldable trailer  101 ,  FIG. 7  and in conjunction with  FIGS. 8   a  and  8   b , depict the foldable trailer  101  in a ‘tilted” orientation that will allow the user to remove or “off-load” various cargos which may have been loaded to the foldable trailer for transport. This may be facilitated while the ball hitch receiver  202  remains attached to the transporting vehicle&#39;s ball hitch (not shown), or may be accomplished in an “unattached” condition. In one embodiment, forward trolley lift leg  307  is utilized as a lifting device. After being unlocked from a forward trolley lift leg lock-arm  313 , remotely by the user, from a “stowed” position on the underside of the forward section&#39;s rectangular box steel frame  306 . The forward trolley lift leg is pushed downward by a double-action hydraulic cylinder  312  that is mounted to the forward section  301  rectangular box steel frame  306  with a bracket or other suitable attachment method that allows full rotation of the cylinder end and having the opposite end attached by bracket that allows full rotation of the opposite end, until the forward trolley lift leg casters  308  come into direct contact with the ground surface. Having leverage advantage, the forward trolley lift leg pushes the foldable trailer&#39;s forward section  301 , center section  401  and rear section  501 , which at this time form a continuously “flat” platform, into an angular orientation where the front is lifted upward and the rear is tilted downward, rotated about the axis of the axle  404 , until the rear section  501  comes into direct contact to the ground at its aft undermost edge. 
     In an embodiment of the invention, while the foldable trailer sections are being rotated, a simultaneous rotation occurs of the tongue section  201  in a downward motion which pushes on a control rod  205 . The control rod is attached to the tongue section  201  by means of a bracket affixed to a cross member of the tongue section&#39;s rectangular box steel frame  204 . The control rod end has a through-hole “eyelet” link by which it is attached with a suitable bolt and threaded hardware, release pin or other method that allows free rotation of the link. The opposite end link is attached, in like manner, to a bracket or other suitable device, which is attached to a cross member on the forward trolley lift leg  307 . This end link also has free rotation. The control rod element  205 , attached thusly to the forward trolley lift leg and the tongue section, serves to control the motion of the tongue section relative to motion of the forward section as the powered forward trolley lift leg raises (or lowers) the forward section. 
     The ball hitch receiver lock pivots on a hinged attachment or other suitable mechanism attached to the underside of the center section  401  rectangular box steel frame element  409 . This action allows for the free rotation of the forward trolley lift leg  307 , without obstruction, in obtaining the amount of travel required to “tilt” the foldable trailer to the desired angle. 
       FIG. 9  is an isometric view of an embodiment of the present invention of the foldable trailer  101  showing the essential frame elements that provide the primary load bearing rectangular box. These are steel frame elements  204 ,  306 ,  409  and  506 . In one embodiment of the invention these elements may be a weldment form of tubular steel material or in other embodiments of the invention may be of pressed or formed steel and riveted or attached together in other acceptable manners to form ridged frames capable of bearing significant loads. The center section  401  is stationary in nature therefore the panels of this section are mounted on side panel stanchion elements  411  which may be made of a material such as square box steel or other suitable material known in the art. In one embodiment, these panels have square tubular straps attached to the panel wall by suitable means which allow it to slide over the mating element side panel stanchion  410 , rendering them fixed in position, but removable for access to the underside of the center deck  403 . In like fashion, the forward side panels  302  and rear side panels  502  slip onto side panel hinge pin elements  410 , which being of a material such as, round tubular steel or a similar structural material, the side panels may be pivoted on the axis of the hinge pin element to their storable state, as illustrated in  FIG. 4 . The side panels, along with their attached end panels, may be “slipped” off of the hinge pin elements for storage “off” the foldable trailer, as an optional storage configuration. 
     In one embodiment suitable gussets and cross members are utilized as structural components to give rigidity to each individual section&#39;s rectangular box steel frame. These gussets and cross members may be of a like material to the parent frame, such as illustrated in  FIG. 9  for rectangular box steel frame elements  204  and  506 , or may be of a combination of other forms of structural steel that may be used, to provide an equal or greater advantage to resisting bend or structural stress to the box steel frame elements. In one embodiment structural steel elements have been attached to the primary rectangular box steel frame  409  of center section  401 , providing attachment points for various elements of the power unit, such as the hydraulic pump, the double-action hydraulic cylinders, or components that may be necessary to drive the separate sections to their “folded” or closed state, and to unfold them as well. For example, there is a form of “hanging” bracket structure for maintaining a “battery box” in a fixed position but allowing easy access for removal or replacement. Also illustrated in  FIG. 9 , are cross members frame rails that are parallel, attached to the hinge bearing rails on each end and set apart to an appropriate distance to the external frame rail elements of the rectangular box steel frame  409 , adjacent to the wheels. Plate steel elements are then attached at some distance and span the gap between each of these rails, to hang the “running” or “slide” components that are required for deployment of the forward support legs  407 . In addition, the essential frame elements may contain appropriate light steel non-structural elements that provide attachment point for various “accessory” components, such as the control module or electrical terminal block to transfer necessary electrical conduits from section to section, or one component to another, for just a few examples. The exterior rails for the rectangular box steel frames may also be utilized to hang various components that provide appropriate lighting aspects, or enhance the protection of the cargos that may be carried from road and tire debris, by mounting tire fenders or other appropriate debris shields well known to the art. 
       FIGS. 10-12  of foldable trailer  101  illustrate the necessary components that operate the forward and rear sections  301  and  501  to their “folded” or closed state.  FIG. 10  is a partial plan view of the foldable trailer of  FIG. 5 , showing just the center section  401  and the rear section  501  components in general, according to one embodiment of the present invention. The rectangular box steel frame element  409  provides a primary structure in which to mount the components responsible for providing the hydraulic forces that act upon the other elements. A hydraulic power unit  417  comprises a rotating vane pump device, electrically driven from an external power source, such as battery element  420 , and provides the primary means of pressure for driving the hydraulic peripherals. In other embodiments, the forces required to provide the lifting actions that leverage the motion of the individually hinged sections of the foldable trailer, may be a pneumatic-over-hydraulic, or a purely pneumatic system, or various others forms known to the art. The hydraulic power unit may be mounted on a hinged mount on one side and a bracket on the other. By loosening the bracket mount the hydraulic power unit may be pivoted up, out of its normal resting pocket, for added convenience for service. It may also be mounted in a near permanent fashion on rubber or plastic bushings with threaded fasteners, or in other ways known to those skilled in the art. 
     The hydraulic power unit is electrically connected to a hydraulic control module element  418  which provides a means of opening and closing proportioning valves and flow direction valves that allow for various combinations of control to the two double-action hydraulic cylinders of the foldable trailer, namely forward double-action hydraulic cylinder  312  (not shown in these views) and a rear double-action hydraulic cylinder  419 . The rear double-action hydraulic cylinder is mounted by means of braces, centrally located on a perpendicular axis to the hinge bearing rail of the rectangular box steel frame  409 , that sandwich the welded end of the rear double-action hydraulic cylinder using a captioned pivot shaft, or may be a bolt and appropriate threaded hardware. The pressurization of the rear double-action hydraulic cylinder, on the end of the cylinder causing “extension” of the ram portion of the cylinder, extends the ram rearward and at some angle downward, initiating the rotation of a rear section swing arm element  424 . The double-action hydraulic cylinder acting upon a rear section lift arm  514  element, causes a rotation about its hinge in an “upward” motion, acting upon rear section lift arm  514 , which rotates upon its pivot link to the second part and a pivot link that resides upon a fixed bracket that is mounted to the rectangular box steel frame  506 . This in turn, lifts the rear section  501  vertically about its hinged link to the center section  401 , to a “folded” state, as is illustrated in  FIG. 12 . 
     Also illustrated in  FIG. 10-12  is a system of structural and activated elements that are deployed to provide primary support to the foldable trailer of  FIG. 1  and  FIG. 2  during the folding operation of forward and tongue sections  301  and  201 . The cantilevered weight of the previously mentioned section elements, contribute to a marked misalignment in weight distribution to the over-all configuration during the activity of folding the forward-of-axle elements of the foldable trailer. This largely results in a “tipping” effect of the foldable trailer, if left unsupported. The use of a combination of components and automation completely eliminate the possibility for this “tipping” effect to occur. 
     During the “folding” action of the rear section element, in one embodiment of the invention, rear trolley support legs  512 , being housed in rear positive-stop rail elements  509 , are deployed in a downward direction by means of a combination of a cable system and support leg return springs element  510 . The rear trolley support legs are a weldment form of two separate shapes of steel, joined together with the lower section being a square tube shape steel that fits interiorly to the square tube shaped steel of the positive-stop rail  509 . The upper section being made from a round tubular steel that extends beyond the length of the positive-stop rails of the rear section. The rear trolley support legs slide on the interior surfaces of the positive-stop rails during the rotation sequence of the rear section to a “folded” state. The control cable element  515  is a continuous twisted multi-strand steel cable, but may be any form of continuous strand material, such as high tensile nylon stranded rope or flexible sheathed carbon fiber rope, for just a few examples. The cables are constrained on the furthest aft points of the trolley support legs by means of eyelet loops and appropriate threaded fasteners, passed through these loops and attached directly to the protruding end of the trolley support legs. The opposite ends of the cables are led over and around several cable sheaves, elements  511 ,  423  and  413 , and terminated on “eyelet” style shackle bolts on the slide block elements  415 . 
     In one embodiment of the invention support leg return springs  510  are “extension” type springs, well known in the art for providing “return-to-position” force for linear motion of mechanisms requiring this type of action. The springs are attached by a “loop” formed on each end of the springs with one end passed through “eyelet” stanchions on the positive-stop rails  509  and at the opposite ends to similar stanchions attached to end plates of the rear trolley support legs  512 . As the cables are tensioned by the rotation of the rear section, the rear trolley support legs are pulled in a downward motion, sliding out of their tubular steel housing of the positive-stop rails, until the support leg casters  513  make contact with the ground surface. In other embodiments of the invention, the rear trolley support legs may be actuated using any form of pneumatic and spring cylinder combination well known in the art. 
     In one embodiment of the present invention, a simultaneous action occurs in the folding of the rear section into an “upright” position. Namely, the deployment of the center section support legs  406 . As the rear section rotates, it provides tension to the cable system previously noted, and is the direct cause, for the motion of the slide blocks  415  and their subsequent action. The slide blocks are of a light weight aluminum material, or may be of some other material, such as plastic or nylon for examples. The slide blocks have a bushing of bronze or slick UHMW plastic, pressed into the block form, that aids in resisting friction and metal to metal abrasion, that may occur during the sliding operation on the slide rod elements  414 . The slide rods are of a material that is resistant to corrosion and their surface can be maintained in a polished state that provides little resistance to the slide blocks that slide on them, or may be of some other like material. 
     The slide blocks also act as a “bracket” in which the center section support legs  406  are attached by captioned pivot pins or by other acceptable forms of hardware. The center section support legs are linked to the slide block on their aft most point which moves pivotally with the slide block, when actuated by the cable systems pulling motion. The support leg is made of a steel “c” channel material, but may be of any other material or shape suitable for withstanding the supporting loads, which mechanisms of this nature encounter. The center support legs are suspended by support leg swing arm elements  421 , one on each side at some distance down each legs length. The swing arm elements are a material suitable to their function, being of steel or other material that will allow the stress and strain tensions known to these types of mechanisms and those skilled in the art. The center swing arm elements are captioned on a pivot axle and spread spacer (not shown) that is sandwiched between two parallel frame members of the rectangular box steel frame  409  of the center section  401 , at their uppermost extremity. To allow the center section support legs full freedom of extension to the ground to provide a support function, the support leg swing arms are drilled and pivoted on a bolt or pin which connects the two swing arms through the support leg, which allows for the extension of the center section support legs  406  and the support leg feet  407 , to make contact with the ground at varying angles, as illustrated in  FIG. 11  and  FIG. 12 . 
     Further illustrated in  FIG. 11  and  FIG. 12  are direction arrows that show the individual motions of the elements that are acted upon by the double-action hydraulic cylinder  419 , as it is pressurized on the “extend” side of its double-action motion, and subsequently on the opposite “retract” side, thus lifting or lowering the rear center section to an “upright” position and subsequently, in the opposite direction, to the open or “transit” position. The other elements being acted upon by this cylinder and the rotation of the rear section, act in unison and simultaneously to the initiation of the hydraulic system by the operator, at the centrally located control panel  405  of the foldable trailer  101 , according to an embodiment of the present invention. 
       FIG. 13   a  is a block diagram showing the hydraulic and control mechanisms of the foldable trailer  101  for the front section. The center section&#39;s rectangular box frame element  409  being shown in dashed line, the forward and center section&#39;s rectangular box frame elements  306  and  506 , being partially viewed and in dashed lines, are represented here, only to give a general understanding as to the location of the elements described hereafter. The center section  401 , being the pivotal section of the foldable trailer, contains the primary elements for powering and operating the hydraulic system that rotates the forward section  401  and the rear section  501  to their storable state, according to embodiments of this disclosure. The hydraulic power unit  417 , being mounted to the rectangular box frame element of the center section on a hinged swing-arm bracket, which allows it to be rotated away from the frame structure for service, and provides the means of hydraulic pressure to the hydraulic systems peripheral devices. The hydraulic power unit motor receives its electrical power from an independent on-board power supply, namely a battery element  420  which is located on a suspended “battery tray” attached to the frame structure of the center section with a suitable strap that protects the battery from unnecessary and possibly damaging vibration. According to one embodiment of the invention, the battery is of a lead acid, exteriorly vented type, but may be a battery of other manufactured forms known to the art, such as, but not limited to, sealed lead-acid and internally vented, glass-matte gel-cell battery technology or deep-cycle lithium-ion technologies are just a few possibilities. The battery supplies the electrical system with 12V electrical current, but may provide other voltages that are common to the art, such as 36V or high-voltage system inverters and converters that will boost or “transform” the voltage from one current type to another, to state a few examples. The battery positive terminal element  427  is connected to a terminal block  416  with copper insulated wire of a sufficient gage to carry the load current, and then to a control module  418  with copper insulated wire and a fusible link for circuit protection. A primary positive voltage link is made then, to the positive terminal of a solenoid mounted on the hydraulic pump&#39;s motor housing. The negative battery terminal  426  is connected to the motor housing of the hydraulic pump providing a ground connection for the system. From the ground connection on the motor housing of the hydraulic pump, a negative copper insulated jumper lead is inter-connected to the negative terminal of the solenoid mounted on the hydraulic pump housing. 
     In one embodiment of the present invention, a terminal block may be provided for various 12V circuit connections to a terminal block  429  that performs a central connection point for lighting and voltage supply to gauges or other instrumentation that may require it. A positive power supply, copper insulated wire, from the positive terminal block  416  can be led to the positive terminal element of the terminal block proving a power supply to all of the electrical peripherals for the foldable trailer. A ground terminal strap supplies ground condition, and is inter-connected from the negative terminal of the terminal block  429  directly to the rectangular box steel frame of the center section  401 . 
     Control module  418  is interconnected to the control panel  405  (depicted in  FIG. 13   b ) with copper insulated wires and a weather resistant conduit, that protect the wires from road debris and salt spray, according to one embodiment of the invention. There are other interconnects then from this same control panel to switches that operate, in a control fashion, the various functions of the motor (not shown) on the hydraulic power unit. The fashions and methods for controlling devices of a hydraulic system are well known to those skilled in the art, therefore, will not be greatly expanded upon in the scope of this disclosure. 
     The forward double-action hydraulic cylinder  312  is pressurized through an inter-connected high-pressure hose that begins at a hydraulic unit valve block element  430  and terminates on the “high” side (the side furthest from the cylinders “ram” end) of the double-action hydraulic cylinder. When this hose is “pressurized”, the ram end of the hydraulic cylinder “extends”, acting upon the forward trolley lift leg mechanism, pushing it downward and toward the foldable trailer&#39;s axle element. The “signal” initiating this is accomplished from the user depressing a button or toggle that provides electrical contact and therefore, completes a circuit of the control unit and subsequently to the hydraulic motor, activating the pump to provide high pressure force to the hydraulic cylinder. Adversely, the same being true for the “retraction” of the double-action hydraulic cylinder when the user operates a separate button or toggle of the control panel. The hydraulic cylinder, being inter-connected by a high-pressure hose that begins at the hydraulic unit valve block and terminates on the “low” side (the side closest to the cylinders “ram” end) of the hydraulic cylinder, is pressurized and forces the cylinder to “retract”. The actions described above result in the lifting of the forward section to a “folded” or closed state and simultaneously “folding” to the underside of the forward section, the tongue section of the foldable trailer  101 . 
     The rear double-action hydraulic cylinder  419  is pressurized through an inter-connected high-pressure hose that begins at a hydraulic unit valve block element  430  and terminates on the “high” side (the side furthest from the cylinders “ram” end) of the double-action hydraulic cylinder. When this hose is “pressurized”, the ram end of the hydraulic cylinder “extends”, acting upon the rear section swing arm  424  mechanism (depicted previously in  FIG. 12 ), pushing it downward and pivotally towards the rear section lift arm element. The “signal” initiating this is accomplished from the user depressing a button or toggle that provides electrical contact and therefore, completes a circuit of the control unit and subsequently to the hydraulic motor, activating the pump to provide high pressure force to the hydraulic cylinder. Adversely, the same being true for the “retraction” of the double-action hydraulic cylinder when the user operates a separate button or toggle of the control panel. The hydraulic cylinder, being inter-connected by a high-pressure hose that begins at the hydraulic unit valve block and terminates on the “low” side (the side closest to the cylinders “ram” end) of the hydraulic cylinder, is pressurized and forces the cylinder to “retract”. The actions described above result in the “folding” of the rear section and simultaneously, the deployment of the forward support legs that provide stability to the foldable trailer, while the forward and tongue sections are being closed to a “folded” state. 
       FIG. 13   b  illustrates a block diagram of the centrally located control panel  405 . It is mounted to the side wall panel of the center section  401  of one embodiment, but may be mounted in any location preference of the individual user, and comprises the controlling switches that a user operates to perform the various “folding” operations of the foldable trailer  101 . To operate the folding of the forward and tongue sections, the toggle switch  431  that may be labeled “Front” with other labels being appropriate for direction, such as “Up” and “Down”, is utilized to initiate pressurizing of the forward double-action hydraulic cylinder. Also housed in the control panel is a toggle switch  432  that may be labeled “Rear” with other labels being appropriate for direction, such as “Up” and “Down”, is utilized to initiate the pressurizing of the rear double-action hydraulic cylinder, which in turn, performs the actions necessary for the “folding” of the rear section and simultaneously deploying the center section support legs. The electrical power aspects of the hydraulic system are initiated by a “keyed” power On/Off switch  433  and directional labels that indicate to the use the “On” position for the key and the “Off” position, as well. Power is provided to the hydraulic system when the key is rotated to the “On” position and adversely, turned off or without power when rotated to the “off” position. 
     According to one embodiment of the invention, a voltmeter is mounted to the face of the control panel that may give the user an indication to the level of charge that the on-board battery has. In other embodiments, the control panel may also include a “pressure” indicator that reflects the “health” of the hydraulic system. The control panel may also have an environmental control panel cover  425  that is hinge mounted to the main body of the control panel and provides the element of protection to switches and gauges from UV or moisture damage. It could be of a material such as plastic or stainless steel, for a few examples. 
       FIGS. 14   a ,  14   b  and  14   c  is a flow chart that describes the process of tilting the trailer to load or unload cargo, and the process of folding the trailer to a compact storage configuration supported entirely on a wheeled trolley with the main wheels off the ground. At step  1401  start process. At logic step  1402 , use of trailer complete? If yes, disregard until logic step  1423 . If no, proceed to logic step  1403  load/unload cargo? If no, return to logic step  1402 . If yes, at step  1404  release hinged rear “tailgate” panel lock and lower to ground level. At step  1405  unlock forward trolley lift leg. At step  1406  rotate keyed on/off switch in control panel to the “on” position. At step  1407  operate toggle switch labeled “up” in control panel (following step  1407 , steps  1408 - 1411  occur simultaneously). At step  1408  forward hydraulic cylinder is pressurized by hydraulic pump on the “extend” side. At step  1409  forward trolley lift leg rotates downward to ground surface. At step  1410  tongue section folds at hinge with forward section under the control of the control rod. At step  1412  foldable trailer forward section rotates “upward” to a “tilted” position. 
     At logic step  1413  desired angle achieved? If no, return to step  1407 . If yes, proceed to step  1414  unload cargo from deck area. At step  1415  operate toggle switch labeled “front” in the direction labeled “down” in control panel until trailer bed rests against positive-stops (Following step  1415 , steps  1416 - 1420  occur simultaneously). At step  1416  forward hydraulic cylinder is pressurized by hydraulic pump on the “retract” side. Step  1417  forward trolley lift leg rotates upward to underside of forward section. At step  1418  control rod link forces tongue section to extend outward and at step  1419  tongue section rotates up to positive-stop. At step  1420  foldable trailer rotates down from “tilted” position. 
     At logic step  1421  trailer all the way down? If no, return to step  1415 . If yes proceed to step  1422  lock forward trolley lift leg into “transit” position. At step  1423  lift rear “tailgate” panel and lock into place. Following step  1423  return to logic step  1402  use of trailer complete? If no, return to logic step  1403 . If yes, proceed to step  1424 . 
     At step  1424  deploy trailer stand to provide trailer tongue section support. At step  1425  disconnect foldable trailer power harness (not shown) from towing vehicle ball hitch. At step  1427  unlock trailer ball hitch receiver and lift trailer tongue section from towing vehicle using trailer stand. 
     At step  1428  remove forward and rear support panels. At step  1429  remove forward and rear center hinge pins. At step  1430  pull forward and rear corner hinge pins from recessed holes. At step  1431  rotate forward side panels with their respective end panels to center section. At step  1432  rotate rear side panels with their respective end panels to center section. At step  1433  unlock foldable trailer rear deck section. At step  1434  open lid of control panel and rotate keyed on/off switch to “on” position. At step  1435  depress toggle switch on control panel labeled “Rear” in the direction labeled “up” (following step  1435 , steps  1436 - 1440  occur simultaneously). At step  1436  rear hydraulic cylinder is pressurized by hydraulic pump on the “extend” side. At step  1437  rear deck rotates in “upright” direction tensioning slide block cable. At step  1438  rear trolley support legs are extended to ground surface. At step  1439  slide block is pulled on slide rod by cable. At step  1440  front support legs travel forward and down to ground surface. 
     At logic step  1441  rear section fully upright? If no, return to step  1435 . If yes, proceed to step  1442  unlock forward trolley lift leg. At step  1443  unlock forward deck section. At step  1444  Depress toggle switch on control panel labeled “Front” in the direction labeled “up”, (following step  1444 , steps  1445 - 1449  occur simultaneously). At step  1445  forward hydraulic cylinder is pressurized by hydraulic pump on the “extend” side. At step  1446  forward trolley lift leg rotates downward to ground surface. At step  1447  control rod link modulates motion of tongue section relative to motion of forward section. At step  1448  tongue section rotates down to underside of forward section. At step  1449  forward section rotates to “upright” position. 
     At logic step  1450  front section fully upright? If no, return to step  1444 . If yes, proceed to logic step  1451  tires lifted from ground? If no, return to step  1444 . If yes, proceed to logic step  1452  front deck fully upright? 
     If no, return to step  1444  and proceed. If yes, proceed to step  1453  lock tongue section receiver hitch to receiver lock mechanism. At step  1454  turn on/off keyed switch to “off”. At step  1455  roll foldable trailer to storage area. At step  1456 , the process is complete. 
       FIGS. 15   a ,  15   b  and  15   c  is a flow chart that describes the process of unfolding the trailer from the compact configuration on the trolley, to a fully-extended configuration with side panels deployed, and ready to load cargo and be used as a towed trailer. At step  1501  start process. At step  1502  roll foldable trailer to a level “open” area. At step  1503  unlock tongue section receiver hitch lock mechanism. At step  1504  open lid of control panel and rotate keyed on/off switch to “on” position. At step  1505  depress toggle switch on control panel labeled “Front” in the direction labeled “down” (following step  1505 , steps  1506 - 1510  occur simultaneously). At step  1506  forward hydraulic cylinder is pressurized by hydraulic pump on the “retract” side. At step  1507  forward trolley lift leg rotates out and upward to underside of forward section. At step  1508  tongue section rotates out and up to extended position under control of control rod link. At step  1510  forward section rotates downward to a “transit” position. At logic step  1511  tires contacting ground? If no, return to step  1505 . If yes, proceed to logic step  1512  front section fully seated? If no, return to logic step  1511 . If yes, proceed to step  1513  forward section lock engages. At step  1514  lock forward trolley lift leg into “transit” position. At step  1515  deploy trailer stand to provide foldable trailer support. At step  1516  rotate foldable trailer stand perpendicular to ground and lock into place. At step  1517  lower trailer stand base until contact with ground is made. At step  1518  depress toggle switch on control panel labeled “rear” in the direction labeled “down” (following step  1518 , steps  1519 - 1523  occur simultaneously). At step  1519  rear hydraulic cylinder is pressurized by hydraulic pump on the “retract” side. At step  1520  rear section rotates in “downward” direction tensioning slide block cable. At step  1521  rear trolley leg return springs retract rear trolley support legs into “transit” positions. At step  1522  slide block is pulled on slide rod by spring motor to rear. At step  1523  front support legs travel “rearward” and up to “transit” position. 
     At logic step  1524  rear section fully rotated? If no, return to step  1518 . If yes, proceed to step  1525  rear section locks into “transit” position. At step  1526  turn on/off keyed switch in control panel to “Off” position. At step  1527  close cover of control panel. At step  1528  rotate forward and rear side panels with their attached end panels to the exterior edge of the trailer respective to their location. At step  1529  push forward and rear corner hinge pins into the recessed holes in each deck section. At step  1530  insert forward and rear center hinge pins. At step  1531  place forward and rear support panels over their respective end panels and secure ends over corner hinge pins. 
     At logic step  1532  use for cargo transport? If no, proceed to step  1536  end process. If yes, proceed to step  1533  unlock trailer ball hitch receiver and lower trailer tongue section onto ball hitch of towing vehicle using trailer stand. Lock trailer ball hitch receiver. At step  1534  attach safety chains (not shown) to towing vehicle ball hitch. At step  1535  connect foldable trailer power harness (not shown) to vehicle. At step  1536  the process is complete. 
     It will be apparent to the skilled artisan that there are many ways the embodiments described in this specification may be altered without departing from the spirit and scope of the invention. There are, for example, many different sizes and depths that may be used for trailers of different size and use when fully deployed. There are also many different ways that the different parts of the trailer may be attached together and assembled. Different numbers and types of hinges may be used between the foldable sections. Different locking mechanisms may be used. The motive power for folding or deploying may be provided hydraulically, pneumatically, or by combinations of these types. In some embodiments human-powered cranks and other force multiplier devices may be used, rather than the power components illustrated in the various examples described. There are many such alterations that may be made without departing from the spirit and scope of the invention.