Patent Document

BACKGROUND OF THE INVENTION 
     Fifth wheel trailers and tow vehicles for fifth wheel trailers are generally well known in the art. Fifth wheel trailers are much longer, roomier, and heavier than typical tent campers and travel trailers, and thus a fifth wheel trailer typically requires a specially modified, relatively heavy tow vehicle such as a heavy duty pickup truck. The front portion of a fifth wheel trailer extends over the rear portion of the tow vehicle so that a portion of the trailer&#39;s weight can be carried over the rear axle of the tow vehicle. In order to accommodate the weight of the trailer a special hitch assembly is generally required. 
     One apparatus for allowing a pickup truck, even a short bed truck, to pull a fifth wheel trailer is to use a sliding hitch assembly as described in U.S. Pat. No. 6,308,977 (&#39;977 patent). The &#39;977 patent describes a sliding hitch assembly with two main parts, a base assembly and a hitch assembly. The hitch assembly attaches to the hitch pin of a trailer; the base assembly is mounted in the bed of a vehicle. The hitch assembly is slidably mounted on the base assembly and operates by mechanically sliding the hitch pin rearward from the cab as the trailer pivots relative to the vehicle. By sliding the hitch rearward, the distance between the hitch pin and the cab increases during turns, thereby allowing turns up to 90 degrees without the trailer contacting the cab. To allow rotation to occur between the hitch assembly and base assembly a capture plate is used to hold the hitch assembly in fixed rotational alignment with the trailer. 
     In the &#39;977 patent, the sliding hitch assembly includes a capture plate which is fastened to the underside of the pin box and which mates with a cutout in the hitch pin slot of the hitch assembly, thereby restricting rotation between the hitch assembly and the pin box. The capture plate of the &#39;977 patent is a flat piece of metal which is sized to mate with the cutout of the hitch pin slot of the sliding hitch assembly. Traditionally, the plate is either fastened directly to the pin box—such as with bolts or screws drilled into the pin box—or by welding or otherwise mounting brackets to the pin box, with the capture plate then mounted to those brackets. 
     Other prior art capture plates are constructed from a flat plate with a wedge extending from the bottom side. The wedge is shaped in a Y-shape and is sized to fill the pin slot on the hitch assembly, thereby preventing rotation between the capture plate and the hitch assembly. The top side of the capture plate has a lip which extends around the entire perimeter of the plate, with screws which mount through the lip and into or against the pin box, thereby preventing rotation between the capture plate and the pin box. 
     The previous approaches to capture plate design have some drawbacks. First, each requires modification to the pin box. Second, the traditional method of restricting rotation between the capture plate and the hitch assembly may form too strong of a connection between the trailer and the hitch assembly such that when rotational forces between the trailer and truck become excessive, costly failure can occur in the trailer, the vehicle, or the hitch. Third, pin box size can vary from trailer to trailer and thus the previous capture plate designs require customized mounting hardware for pin boxes of different dimensions. 
     Accordingly, there exists a need for a capture plate which can be removably mounted to a fifth wheel trailer&#39;s pin box without modifying the pin box. There also exists a need to design a capture plate which will preferentially fail so that the trailer, vehicle and hitch assembly are protected from damage when subjected to excessive stress. There further exists a need to design a capture plate which is readily and inexpensively adjustable to accommodate variously sized pin boxes. 
     SUMMARY OF THE INVENTION 
     The capture plate according to the present invention allows a fifth wheel trailer to be mounted to a sliding hitch assembly and prevents rotation therebetween. The capture plate is removably mounted on the pin box of a fifth wheel trailer and has a lip around the top edge which prevents rotation between the pin box and the capture plate. The capture plate has a protrusion feature, or wedge, affixed to the bottom side, which mates with the pin slot on a hitch assembly and serves to prevent rotation between the capture plate and the hitch assembly. Thereby, the capture plate prevents rotation between the trailer and the hitch assembly. 
     Accordingly, it is an object of the present invention to provide an improved capture plate which restricts rotation between a fifth wheel trailer and a sliding hitch assembly. 
     It is an object of the present invention to provide an improved capture plate which may be mounted to a pin box without modification to the pin box. 
     It is an object of the present invention to provide an improved capture plate which can be adjusted to attach to various sizes of pin boxes. 
     It is an object of the present invention to provide an improved capture plate which has a quick-connect fastener which anchors the capture plate to the trailer pin box. 
     It is another object of the present invention to provide an improved capture plate which has a lip that will preferentially fail in excessive stress situations in order to prevent damage to either the hitch assembly or the trailer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A preferred embodiment of this invention has been chosen wherein: 
         FIG. 1  is a fragmentary view of the trailer, truck and sliding hitch assembly. 
         FIG. 2  is a perspective view of the sliding hitch assembly, with the capture plate and pin box mounted on top. 
         FIG. 3  is an exploded view of the pin box, capture plate and sliding hitch assembly. 
         FIG. 4  is an exploded view as seen from below of the pin box, capture plate and sliding hitch assembly. 
         FIG. 5  is an exploded view of the capture and hitch plates. 
         FIG. 6  is a perspective view of the capture plate mated to the hitch plate. 
         FIG. 7  is a perspective view of the capture plate mounted on the sliding hitch assembly. 
         FIG. 8  is a perspective view of the top side of the capture plate. 
         FIG. 9  is a perspective view of the bottom side of the capture plate. 
         FIG. 10  is a fragmentary view of the pin box engaged with the capture plate shown secured to the king pin by a fastener. 
         FIG. 11  is a top side perspective view of the capture plate with its spacing shims in exploded form. 
         FIG. 12  is an alternative embodiment of the capture plate. 
         FIG. 13  is an alternative embodiment of the capture plate. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The embodiment herein described does not intend to be exhaustive or to limit the invention to the precise form disclosed. It has been chosen and described to explain the principles of the invention and its application and practical use to best enable others skilled in the art to follow its teachings. 
       FIG. 1  shows a trailer  10  connected to a sliding hitch assembly  18 , which in turn is mounted to a vehicle  20 . Trailer  10  includes a pin box  12  with a king pin  14  downwardly extending therefrom. King pin  14  engages a locking jaw  16  on sliding hitch assembly  18 , thereby securing the trailer to the hitch assembly. Sliding hitch assembly  18  is mounted in the bed of a vehicle  20  to enable the vehicle to tow trailer  10 . Vehicle  20  may be a short-bed pickup truck. The sliding hitch assembly  18  moves king pin  14  away from the cab of vehicle  20  when turning to prevent trailer  10  from contacting vehicle  20 , such as shown in U.S. Pat. No. 6,308,977, incorporated herein by reference. 
     The pin box  12  is mounted on sliding hitch assembly  18  with a capture plate  22  sandwiched therebetween, as shown in  FIG. 2 .  FIG. 3  shows an exploded view of pin box  12 , capture plate  22  and sliding hitch assembly  18 . With capture plate  22  anchored to pin box  12 , king pin  14  passes through a pin hole  24  in capture plate  22  and is secured in locking jaw  16  on sliding hitch assembly  18 , thereby connecting trailer  10  to sliding hitch assembly  18 . A lip  26  restricts rotation between pin box  12  and capture plate  22 , and a wedge  28  restricts rotation between the capture plate and hitch assembly  18 , as discussed in more detail below. 
     A hitch plate  32  forms the top of sliding hitch assembly  18  and has a pin slot  30 . Pin slot  30  is defined as an open channel which accepts king pin  14  and houses a locking jaw  16  which locks king pin  14  in place when the trailer is docked on the sliding hitch assembly. Wedge  28  is fixed to the bottom of capture plate  22  and is sized to mate with pin slot  30 . Wedge  28  fits restrictively into pin slot  30  near locking jaw  16  on sliding hitch assembly  18 , whereby rotation is prevented between capture plate  22  and sliding hitch assembly  18  as shown in  FIGS. 5 ,  6  and  7 . Wedge  28  may have a tapered leading edge  29 , as shown in  FIG. 9 , such that the tapered edge serves to guide the wedge into pin slot  30  as capture plate  22  is docked on sliding hitch assembly  18 . 
     Capture plate  22  is formed from a generally flat plate with pin hole  24  forming an aperture through the plate which accepts king pin  14  as shown in  FIGS. 8-11 . Capture plate  22  has a front edge  34 , a back edge  36 , a top side  38  and a bottom side  40 . Wedge  28  extends from bottom side  40 , preferably positioned between back edge  36  and pin hole  24 . Lip  26  extends from top side  38  and is located around a portion of the perimeter of capture plate  22 , preferably around front edge  34 .  FIG. 8  shows lip  26  traveling around nearly the front half of capture plate  22 . Other embodiments envision various lip configurations such as lip  26  terminating near back edge back edge  36 , or extending only far enough to accommodate shims  42 , as shown in  FIG. 12  and  FIG. 13  respectively. Other embodiments envision lip configurations which restrict rotation between the pin box and the capture plate such as the use of multiple lips, or a lip contacting the back portion of the pin box or other similar configurations. 
     In one embodiment, lip  26  runs generally parallel to the outer edges of the top side  38  of capture plate  22 . Lip  26  circumscribes a sufficient part of pin box  12  so that rotation is prevented between pin box  12  and capture plate  22  as shown in  FIG. 13 . The outer dimensions of pin box  12  may vary among trailer manufacturers and therefore one or more shims  42  may be secured to lip  26  to accommodate different pin boxes, thereby allowing a restricted fit between capture plate  22  and pin box  12  such that rotation is prevented therebetween as discussed in more detail below. With capture plate  22  mounted on pin box  12 , top side  38 , lip  26  and any shims  42  contact pin box  12 . Lip  26  may terminate in a flared end  44 , as shown in  FIG. 8 . 
     Shims  42  are defined as one or more spacers which may be mounted to lip  26  in order to custom fit capture plate  22  to pin box  12 . Shims  42  can be secured to lip  26  by a fastening means known in the art. Here, a bolt  50  passes through a hole in each shim  42  and through a corresponding hole in lip  26  and then secures into a nut  51 . The number of shims  42  shown in  FIG. 11  is merely illustrative; the number of shims used in practice will depend on the dimensions of the pin box to which the capture plate is attached to allow for connection between the pin box and the capture plate. 
     Lip  26  is attached to capture plate  22  with a fail-safe bond such that the lip may preferentially fail before the rotational force between trailer  10  and vehicle  20  becomes great enough to damage any of the attached components such as pin box  12 , trailer  10 , sliding hitch assembly  18  or vehicle  20 . Lip  26  is designed to fail by bending outwardly or separating from capture plate  22  when subjected to a sufficient rotational force, thus allowing pin box  12  to rotate relative to capture plate  22 . 
     Wedge  28  is an extension of capture plate  22  adapted for mating with pin slot  30 . As discussed above, wedge  28  mates with pin slot  30  of hitch assembly  18  to prevent rotation between capture plate  22  and the hitch assembly. Wedge  28  may be fixed to capture plate  22  by any method known in the art, including, but not limited to, welding, riveting, bolting, or any other fastener as is known in the art. Alternatively, wedge  28  and capture plate  22  may be formed as a single piece. Wedge  28  is shaped to contact pin slot  30  to prevent rotation of the capture plate relative to the hitch assembly. A fastener, such as a set screw  46 , is carried on the underside of capture plate  22 , and serves to anchor capture plate  22  to pin box  12 , preferably to king pin  14 . With set screw  46  tightened against king pin  14 , capture plate  22  is held in anchored contact with pin box  12 . Fastener  46  is designed as a quick-release fastener for readily attaching and detaching capture plate  22  to pin box  12  without damaging or modifying the pin box. Fastener  46  is an improvement over the prior art as it allows attachment of a capture plate to a pin box without modifying the pin box, and does so with a single quick-release fastener. In the preferred embodiment, fastener  46  is carried by wedge  28 . In the preferred embodiment, wedge  28  is fixed to the bottom side  40  of capture plate  22  between pin hole  24  and back edge  36  as shown in  FIG. 9 . Wedge  28  may take many shapes; in one embodiment wedge  28  is a hollow D-shaped extension of capture plate  22 , with a tapered leading edge  29  to allow for smooth mating with pin slot  30 . In a further embodiment, wedge  28  is a solid polygonal extension of capture plate  22 . The description herein contemplates other embodiments of wedge  28  which mate with a pin slot to prevent rotation between a capture plate and a hitch assembly, and which carry a quick-release fastener for readily attaching and detaching the capture plate to the pin box without modifying the pin box. 
     In one embodiment, the front edge  34  of capture plate  22  terminates in an angled portion  48 . With capture plate  22  mounted on pin box  12 , angled portion  48  serves as a ramped leading edge for engagement with pin slot  30 . In an alternative embodiment, lip  50  extends the length of the front edge of the capture plate with arms  52  and  54  extending perpendicular therefrom, as shown in  FIG. 12 . One or more shims  56  may be secured to arms  52  and  54 . In this embodiment, arms  52  and  54  are shorter in length than the embodiment shown in  FIG. 8 , being just long enough to accommodate shims  56 . Another embodiment of the invention has arms  58  and  60  extending from near the front edge to near the back edge of the capture plate with shims  62  sized to fit the length of arms  58  and  60 , as shown in  FIG. 13 .

Technology Category: 7