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CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/210,038 filed on Mar. 16, 2009 which is hereby incorporated by reference in its entirety. 
     
    
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       REFERENCE TO A MICROFICHE APPENDIX 
       [0003]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    The present invention generally relates to ladder assemblies for a vehicle&#39;s tailgate and more particularly to a quick-disconnect ladder assembly suited for use with a variety of vehicles such as flatbed trucks, sports utility vehicles, and pickup trucks. 
         [0006]    2. Description of the Related Art 
         [0007]    Because of the availability of options that make their ride as comfortable as many of the passenger vehicles as well as their functionality and convenience, pickup trucks today have become one of the most popular vehicles on the road not only for company or work vehicles but also as a family vehicle. In spite of its popularity as a family vehicle, the pickup truck still has some undesirable features. One such feature is that many users experience trouble accessing the bed portion of the truck. Because many are not tall enough to reach over the sides into the bed, they usually stand on the tire in order to access items that may be located in the bed. Access is possible by climbing over the sides into the truck bed but because of its height, such action often does not come without risk of injury. Because the vehicle bed is typically some distance from the ground surface, getting into and out of the vehicle bed for some can pose a severe injury problem. For example, jumping out of the vehicle bed can cause injury to feet, ankles, legs, as well as other parts of the human body should one fall on such attempt. Further, maintaining balance while climbing into or out of the bed portion may be difficult, especially for the elderly, weak, and the young. 
         [0008]    To overcome these safety concerns, it has been proposed to use a ladder to get into or out of the vehicle bed. Most conventional ladders are unpractical because they are too large and take up significant storage space within the bed of the vehicle. Smaller ladders move around in the bed during travel and can easily be stolen if they are not secured to the vehicle. Unfortunately, most ladders whether large or small, do not have hand rails resulting in personal injury should a person lose balance and fall off the ladder. Ladders also require flat surfaces to stand on for proper stability. Such requirement would demand that the driver park the vehicle on a flat surface, which is generally inconvenient since many ground surfaces are inclined. 
         [0009]    Because of these various considerations, the prior art is replete with prior art proposing solutions to various safety problems. For example, Peacock, U.S. Pat. No. 4,757,876, discloses a collapsible step ladder attached to the inside of a tailgate utilizing a pair of leveling braces that are positioned to hold a platform in a horizontal position when the step ladder is fully deployed. Unfortunately, the legs are not self-adjusting, and require bending down to adjust each leg separately. This is difficult to accomplish for a senior citizen or impaired individual. Further, the hinges connect the invention directly to the tailgate. Such connection increased the risk of structural failure, especially with lateral movements of the ladder, increasing the risk of damage to the tailgate as well as injury to a user. 
         [0010]    Barksdale, U.S. Pat. No. 4,191,388, discloses a foldable ladder directly attached to the inside surface of a tailgate with an L-shaped bolt which is secured on one end by a nut. The problem with this tailgate ladder is that it does not come into contact with the ground and therefore it is subject to horizontal and vertical movement as the truck moves during use of the ladder. Again, as in Peacock above, this significantly increased the risk of injury to a user as stability is reduced during use. This is especially critical since Barksdale offers no handle that a user can use during ascending or descending the ladder. 
         [0011]    Llewellyn, U.S. Pat. No. 4,848,821, discloses a foldable tailgate ladder attached to the outside panel of a tailgate. The ladder is attached to one side of the pickup truck where a cable attached to the tailgate and pickup body is provided with a handle to provide assistance in climbing on or off of the vehicle. Attaching the ladder to the outside panel of the tailgate reduces the aesthetics of the truck. Further, the connecting bolts are visible and may enhance corrosion to the outer panel painted surface. Further, connecting of bike racks or other auxiliary devices to the rear tailgate is no longer possible. 
         [0012]    Several prior art patents disclose ladders which are slidable, pivotable, or telescopingly mounted with respect to the tailgate. In Burdette, U.S. Pat. No. 5,205,603, a tailgate ladder is disclosed which is arranged for the extension and retraction of a tailgate structure interiorly of a tailgate portion of the truck. Unfortunately, the handle is not integral to the invention and thus must be separately stored increasing the risk of loss. 
         [0013]    Rolson, U.S. Pat. No. 6,003,633, discloses a detachable ladder for accessing the bed of a flatbed truck or trailer. The attachment bracket is fixedly attached to a rectangular metal post which is sized to fit into one of the stake pockets which are intended for receiving stakes or the like which extend the carrying capacity of the trailer. Rolson proposes that the pivotal connection between the ladder and the attachment bracket is made by two links so that the ladder can be positioned well outside the trailer frame while in use but can be pivoted upwardly and inwardly to permit the ladder to be stowed on the trailer bed without projecting outwardly beyond the trailer frame. The problem with Rolson&#39;s ladder is that if there is no room available on the trailer bed to pivot the ladder upwardly and inwardly to stow the ladder on the bed, the user must remove the post from the stake pocket and find another stake pocket to install the post such that the room is available on the bed of the truck to store the ladder after it is pivoted upward and inward to permit the ladder to be stowed on the bed without interfering with the load on the trailer or without projecting outwardly beyond the trailer frame. 
         [0014]    Finally, Riggs, U.S. Pat. No. 7,080,713, discloses a ladder assembly that attached to the interior surface of the cargo space of a vehicle. A pivot armature attached to a mounting bracket by a pivot member with a yoke and adjustment guides at one end constitutes the mounting plate interconnecting the ladder to the pivot plate. The ladder is removable from the yoke by actuating the adjustment pins  168 . However, it is not clear how the edge of the C-channel is removed from the raised protrusion to release the ladder from the mounting bracket. A further problem with Riggs is that if the ladder is stored within the cargo space while cargo such as rocks, sand, or dirt has been loaded, such cargo will be sufficiently high within the box to cover the adjustment guide mounted on the lowest leg or rail as well as the second joint, apertures of the adjustment guides and adjustment pins adapted to couple the yoke to the apertures. Without thoroughly cleaning out each one of these structural elements of the mounting plate it is conceivable that these elements become corroded and are unable to function properly in the long run. 
         [0015]    Accordingly, the need for an improved ladder assembly that allows a user to exit and enter a vehicle bed in a safe and convenient way still exists. There also exists a need for a trailer bed ladder assembly that has some form of a handrail to assist a user while ascending or descending the ladder. Further it is desirable that the ladder be removable from the mounting bracket so that it is not exposed to typical cargo, i.e., sand, dirt, stone, cement, etc., carried in the cargo bed of a pickup truck and the ladder can be stored in any convenient stowage when not in use. 
       SUMMARY OF THE INVENTION 
       [0016]    The invention is directed to a ladder assembly for attachment to a flatbed of a truck or tailgate of a pickup truck. The assembly includes a mounting plate for attachment to the bed of a flatbed truck or the inside panel of a tailgate of a pickup truck. The ladder has a pair of side members and a plurality of rungs extending there between and a pivot plate mounted to the mounting plate to allow rotatable movement of the ladder from a storage position wherein the ladder is secured to the interior surface of the cargo space of the vehicle to a deployed configuration wherein the ladder is rotated and pivoted so as to be extended from the interior surface of the cargo space of the vehicle to the ground surface such that a user can safely access the cargo space of the vehicle by climbing the ladder. 
         [0017]    In one embodiment, the present invention provides a ladder assembly for a pickup truck having a tailgate. The ladder assembly includes a mounting plate attached to the interior surface of the tailgate of the pickup truck, a ladder having two side members and a plurality of rungs extending therebetween, a pivot plate interconnecting the ladder to the mounting plate. The pivot plate retains the ladder in a storage configuration against the tailgate when the tailgate is in the closed position such that the side members of the ladder extend to the longitudinal width of the tailgate in the storage configuration and wherein the pivot plate permits the ladder to be rotated and then pivoted downwards to the ground in a deployed configuration. 
         [0018]    Alternative to the storage configuration against the tailgate when the tailgate is in the closed position, the ladder and pivot plate may be rotated on the mounting plate so that the pivot plate disengages from the mounting plate and the ladder and pivot plate can be disconnected from the mounting plate and stored in a separate storage location on the vehicle to avoid exposure of the ladder to the cargo carried within the bed of the truck avoiding contaminating the ladder and pivot plate with sand, dirt, stones, etc., carried in the bed of the vehicle. 
         [0019]    In a further embodiment of the invention, the ladder is provided with adjustable extensions which attach telescopingly to the side members to provide adjustment, in height, since the height of the tailgate to the ground can vary on different vehicles. The extensions are telescopingly adjustable for situations where the ground is uneven so that the ladder can be maintained substantially in a vertical plane to the tailgate. 
         [0020]    A further feature of the invention is that a side member also houses a pivoting handle which is raised from a confined locked position within the envelope of one or the side members and pivoted to an upright locked position when the ladder is in a deployed position to provide a user a stable hand hold assist in ascending or descending the ladder. 
         [0021]    It is the principal object of the present invention to provide an improved ladder mountable on the inner surface of a tailgate or end gate of a pickup truck to facilitate access to the truck bed. 
         [0022]    It is a further object of the present invention to provide an improved ladder which stows flat against the inside surface of tailgate of a vehicle when not in use, and can be rotated and unfolded so as to suspend from the tailgate to provide steps to access the truck bed of the vehicle. 
         [0023]    It is a further object of the invention to provide an improved ladder mountable on the inner surface of a tailgate of a vehicle with a mounting plate means wherein the attachment plate and ladder is conveniently disconnected from the tailgate to allow the ladder to be stored on the vehicle and not attached to the tailgate, thereby not exposing the ladder to the cargo, i.e., sand, dirt, cement, etc., that will be carried in the bed of the vehicle. If needed, the ladder can be re-attached to the tailgate to assist in accessing the cargo for unloading. 
         [0024]    It is still a further object of the invention to provide a tailgate ladder that presents minimal interference to the loading and unloading of cargo from the vehicle. 
         [0025]    Another object of the invention is to provide a tailgate that includes a handle assist for the elderly, weak, and young to provide support while ascending and descending the ladder. 
         [0026]    Another object of the present invention is to provide a tailgate ladder which is simple, rugged, and requires only minimum time to stow or extend, as well as to remove and re-attach the ladder for use. 
         [0027]    Other objects and advantages of the invention will be apparent from the following detailed description and appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  is a perspective view of the ladder assembly of one embodiment of the invention showing the ladder assembly attached to the tailgate of a vehicle; 
           [0029]      FIG. 2  is a top view of the mounting plate attached to the tailgate of the vehicle with the ladder mounted to the pivot plate and the pivot plate attached to the mounting plate illustrating the stowage position on the tailgate after the tailgate is rotated to its open position; 
           [0030]      FIG. 2A  is a cross-sectional view taken along lines  2 A- 2 A in  FIG. 2 ; 
           [0031]      FIG. 3  is a top view of only the mounting plate attached to the tailgate with mounting bolts as shown in  FIG. 2 ; 
           [0032]      FIG. 4  is a top view of only the pivot plate in the position as mounted to the mounting plate as shown in  FIG. 2 ; 
           [0033]      FIG. 5A  is the top view of the pivot and mounting plates in position similar to  FIG. 3  with the pivot plate rotated counterclockwise an additional  90 ° from the  FIG. 3  position whereat the slots in the mounting plate become aligned with the tabs of the pivot plate such that the pivot plate is removable from the mounting plate; 
           [0034]      FIG. 5B  is a side view of the invention with the ladder in the deployed position to allow access to the bed of the vehicle; 
           [0035]      FIG. 6  is a perspective view of one of the leg members illustrating a sliding U-channel member of rectangular configuration sliding within the U-shaped leg member to provide telescopic adjustment for the height of the ladder; 
           [0036]      FIG. 7  is a plan view of the left leg member which illustrates the locked storage position of a pivotable handle which is deployed when the ladder is in use; and 
           [0037]      FIG. 8  is a cutaway isometric view of the tailgate illustrating a second mounting bracket for the ladder while in a stowed configuration. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0038]    With reference to  FIG. 1 , there is illustrated in isometric view a ladder assembly configured in accordance with the preferred embodiment of the present invention. The ladder assembly is mounted to the tailgate of a pickup truck and adapted to assist a user in accessing the bed of the pickup truck. It is understood that the ladder assembly can be used with pickup trucks of different sizes as well as a variety of other vehicles, such as flatbed trucks, cargo trucks, sports utility vehicles, and the like. 
         [0039]    As illustrated in  FIG. 1 , the pickup truck  10  includes a cab (not shown) at the front end thereof and a vehicle bed  12  at the rear end  14 . The vehicle bed  12  is of conventional rectangular shape and includes upright sidewalls  16  extending rearwards from the cab (not shown) to the rear end  14  of the vehicle  10 . The pickup truck  10  also includes a tailgate  18  extending between the upright sidewalls  16  of the truck  10 . The tailgate  18  is pivotally attached to the vehicle bed  12  of the truck  10  to permit movement between an open and closed position. 
         [0040]    As illustrated in  FIG. 1 , the ladder assembly  20  has a frame section  22  defined by parallel support legs or rails  24  with a plurality of rectangular steps  26  fixed between the parallel support legs  24 . The upper end  28  of each of the parallel support legs  24  is pivotally connected to a pivot plate  30  which in turn, is rotatably mounted to a mounting plate  32  which rests on the inner panel  34  of the tailgate  18  and securely fastened thereto with self-tapping screws  35 . The pivot plate  30  and mounting plate  32  configuration will be described in greater detail below. 
         [0041]    As illustrated in  FIG. 2 , the pivot plate  30  is mounted to the mounting plate  32  by interlocking a plurality of tabs  36  on the pivot plate  30  with a plurality of slots  42  in the mounting plate  32 . With reference to  FIGS. 2-6A , the interlocking arrangement will be discussed in detail. The mounting plate  32  is mounted directly to the inner panel  34  of the tailgate  18  by a series of self-tapping screws  35 . Any combination of eight mounting holes can be used to secure the mounting plate  32  to the tailgate  18 . 
         [0042]    In a portion of the mounting plate  32  is located a cylindrical through-passage  40  with three peripherally angularly spaced slots  42  for receiving three offset tabs  36  located on the bottom  44  of the pivot plate  30 . The offset tabs  36  are stamped in a depressed portion  46  made in the pivot plate  30 . This depressed portion  46  or offset is cylindrical in form but may be configured in any form. The offset tabs  36  of the pivot plate  30  are circumferentially spaced to compliment the slots  42  in the mounting plate  32  such that when the pivot plate  30  is placed on the mounting plate  32  with the offset tabs  36  angularly aligned with the slots  42  in the mounting plate  32 , the offset tabs  36  will drop into the slots  42  as shown in  FIG. 5A  and upon rotating the pivot plate  30  with respect to the mounting plate  32 , the offset tabs  36  will interlock the pivot plate  30  to the mounting plate  32  by moving rotatably and interlocking with the material of the mounting plate  32  arcuately located  48  between the slots  42  as shown in  FIG. 2 . The angular location of the slots  42  and offset tabs  36  arrangement is by choice, depending on what position one wants the slots  42  to align with the offset tabs  36  to enable disconnecting the pivot plate  30  with the attached ladder assembly  20  from the mounting plate  32 . In the preferred embodiment, two of the offset tabs were angularly spaced approximately 135° apart from the third offset tab. Again, any convenient spacing may be used to permit the disconnection of the pivot plate  32  from the mounting plate  30  at a convenient angular position. 
         [0043]      FIGS. 5A-5B  illustrate the quick disconnect feature of the present invention. As illustrated in  FIG. 5A , when the pivot plate  30  is rotated counterclockwise from the stowed position shown in  FIG. 1  such that the ladder assembly  20  is parallel to the longitudinal direction of the vehicle  10 , the offset tabs  36  on the pivot plate  30  angularly align with the slots  42  in the mounting plate  32  to enable disconnecting the ladder assembly  20  and pivot plate  30  from the mounting plate  32 , by lifting the pivot plate  30  straight up from the mounting plate  30  from the position shown in  FIG. 5A . The ladder assembly  20  and pivot plate  30  are rotated 90° clockwise from the position shown in  FIG. 5A  to move the ladder assembly  20  into its stowed position lateral to the longitudinal direction of the vehicle  10 . The ladder assembly  20  and pivot plate  30  in  FIG. 5B  have been rotated clockwise an additional 90° clockwise so as to be substantially perpendicular with respect to the tailgate  18  as well as pivoted downwards about the upper end  28  attachment points to allow the lower portion of the legs or rails  24  of the ladder assembly  20  to rest on the ground and permit the user to climb up the ladder assembly  20  and have access to the vehicle bed  12  of the pickup truck  10 . 
         [0044]    To assist the user in climbing the ladder assembly  20 ,  FIG. 7  illustrates a plan view of a pivotable handle  50  which can be stored within the U-shaped channel of either right or left leg members  24 . The pivotable handle  50  is deployed by retracting the spring loaded detent  52  to unlock (push in direction of arrow A) the pin  54  from the aperture  56  in the wall section  58  of the U-shaped channel of the leg member  24 . Thereafter, the pivotable handle  50  is pivoted upwards about the attached pivot joint  60  until the spring loaded detent  52  is again moved into a second aperture  62  in the wall section  58  of the U-shaped channel and the pin  54  of the spring loaded detent  52  is locked into the aperture  62  to enable the pivotable handle  50  to assist a user in ascending or descending the ladder assembly  20  attached to the pivot plate  30 . 
         [0045]    Referring now to  FIG. 6 , there is shown a bottom portion  64  of the leg members  24  which is vertically telescoping via a sliding member  66  of the same cross-sectional configuration as the leg members  24  but smaller in size so as to slidingly nest within the U-shaped configuration of the leg members  24 . 
         [0046]    A series of aligned vertically spaced openings  68  are located in the web portion of the U-shaped leg member  24 . A complementary series of holes  70  are made in the telescoping sliding member  66 . Because tailgate heights may vary from vehicle to vehicle, the telescoping sliding member  66  can be adjusted when the ladder assembly  20  is initially installed on the vehicle  10 . The initial adjustment is made permanent by two bolts and nuts  74  that are mounted in openings  68  in the U-shaped leg member  24  and holes  70  in the telescoping sliding member  66 . The telescoping sliding member  66  can be adjusted by retracting or extending the telescoping sliding member an appropriate distance and thereafter engaging the bolts and nuts  74  with conveniently appropriate holes. Once the initial adjustment is completed, there should be no need for further adjustment since the distance from the tailgate  18  to the ground does not change on the same vehicle. A user, however, has the choice of further adjustment, if desired, to change the angle at which the ladder stands deployed with respect to the vehicle.  10   
         [0047]      FIG. 6  also illustrates another embodiment of the invention wherein a roller member  78  is mounted to the bottom of the sliding telescoping member  66  to permit the ladder assembly  20  to move in a linear direction such as when a user ascends the ladder assembly  20  and the additional load of the weight of the user in the bed  12  of the vehicle  10  will cause the tailgate  18  to lower slightly due to the weight in the vehicle bed  12  acting on the springs of the vehicle  10 . Rather than having the bottom portion  64  of the ladder assembly  20  be forced into the soil as the vehicle bed  12  receives a load or the tailgate  18  rises, if the ladder assembly  20  is on a concrete surface, the roller members  78  will move in a linear direction slightly and change the vertical inclination of the ladder assembly  20  to compensate for the movement of the bed  12  of the vehicle as it takes on a load in the bed  12 . The roller members  78  are attached to a hole  70  of the sliding member by a bolt  76 . 
         [0048]    In  FIG. 8  there is illustrated another feature of the invention. In order to secure the ladder assembly  20  in its stowed position, a latch pate  80  is mounted to the tailgate  18  near the bottom portion  64  of the leg members  24 . The latch plate  80  has an offset portion  82  which extends towards the front of the vehicle  10 . The offset portion  82  is adapted to receive a keeper finger  84  as the ladder assembly  20  is rotated into the stowed position from the deployed position. While the ladder assembly  20  is in the stowed position, the keeper finger  84  resides within the slot  86  made by the offset portion  82  so that the lower portion  64  of the ladder assembly  20  is secured to the tailgate  18  while in a stowed position. 
         [0049]    Although the above-disclosed preferred embodiment of the present invention have shown, described, and illustrated the fundamental features of the present invention, it should be understood that various omissions, substitutions, and changes in the form of the details of the various elements, systems, and/or methods illustrated may be made by those skilled in the art without departing from the scope of the present teachings. Consequently, the scope of the invention should not be limited by the foregoing described preferred embodiment, but should be defined by the appended claims.

Summary:
A quick connect/disconnect ladder assembly includes a mounting plate attached to a vehicle&#39;s tailgate of a truck bed, a pivot plate mounted thereto to which is attached a ladder on which to ascend to gain convenient access to the bed of the pickup truck. When the tailgate is opened, the ladder can be pivoted away from the vehicle bed to a substantially perpendicular position with respect to its original orientation against the tailgate of the truck. The ladder is then pivoted downwards such that the lower end of the rails or legs contact the ground surface. The ladder is further pivotable counterclockwise to its stowed position on the tailgate to disconnect the ladder and pivot plate from the mounting plate.