Abstract:
A hitch for coupling a trailer to a towing vehicle includes a hitch assembly and a base assembly. The hitch assembly pivots between an aligned position and a turning position as the towing vehicle turns. A bearing assembly rides between the hitch assembly and the base assembly. The bearing assembly guides the hitch assembly between the turning and aligned positions. The base assembly has an anchor assembly which prevents the hitch assembly from sliding fore or aft when in the aligned position.

Description:
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 is carried over the rear axle of the tow vehicle. In order to accommodate the weight of the trailer, a special hitch assembly is required. The vehicle most commonly used to tow fifth wheel trailers is a pickup truck having an 8 foot bed length. 
     But, recently, there has been a consumer trend toward extended cab pickup trucks, which have longer, roomier cabs. These trucks have greatly expanded interior cargo volume and also have a second row of seats for accommodating additional passengers. Unfortunately, most of these extended cab pickups are built on a standard wheelbase chassis because consumers prefer the driving characteristics of a shorter truck and, accordingly, the bed of these trucks is typically 6 feet long rather than 8 feet long. Although these shorter bed pickups have the towing capacity to handle fifth wheel trailers, they do not have enough clearance between the axle and the rear of the cab to allow the trailer to pivot to a 90 degree angle without contacting the cab which could damage the truck and severely injure any occupants. In most circumstances, a fifth wheel trailer will contact the cab of a short bed pickup at angles much less than 90 degrees. 
     One method for allowing a short bed pickup truck to pull a fifth wheel trailer is to use a sliding towing 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 box of a trailer; the base assembly is mounted in the bed of a vehicle. The sliding towing assembly operates by mechanically sliding the hitch pin rearward from the cab as the trailer pivots. 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. 
     This aforedescribed hitch assembly can be improved upon. First, the contact between the slide plate and the guide rails causes friction and noise as the hitch assembly slides. Friction can lead to stress or strain on the components of the hitch assembly, and noise from the hitch assembly can cause discomfort or annoyance to the driver and passengers, as well as a perception of low quality construction. Second, when the truck and the trailer are aligned and the truck accelerates or decelerates the slide plate has a tendency to rock or slide. 
     Accordingly, there exists a need for an improved sliding towing assembly that allows fifth wheel trailers to be towed using short bed pickup trucks, but minimizes noise and friction during turning. There also exists a need to minimize hitch movement during acceleration and deceleration when the trailer and vehicle are aligned. 
     SUMMARY OF THE INVENTION 
     The sliding towing assembly, according to the present invention, allows fifth wheel trailers to be towed using short bed pickup trucks. The present sliding towing assembly allows the hitch pin to slide away from the cab, when the truck turns, with minimal friction or noise. The present sliding towing assembly holds the hitch pin in place—preventing the hitch from moving longitudinally, when the truck and trailer are aligned. 
     The sliding towing assembly is composed of two sub-assemblies: a hitch assembly and a base assembly. The base assembly attaches to the bed of a pickup truck. The hitch assembly latches to a king pin box, thereby connecting the hitch assembly to a trailer. The hitch assembly is carried by the base assembly. The base assembly includes two guide rails. The hitch assembly includes a bushing. The bushing is mounted on a lever arm. A bearing box is carried by the lever arm, about the bushing and contacting the guide rails, thereby guiding the bushing between the guide rails and reducing friction between the base assembly and hitch assembly. A bearing plate rests on top of the guide rails. The bearing plate is sandwiched between the hitch assembly and the guide rails to reduce friction therebetween. The bearing boxes and plates are preferably constructed from a durable plastic with a low coefficient of friction such that they can withstand the forces placed upon them during towing, and reduce friction and dampen noise. Further, the use of plastic bearings reduces the need to use grease or other lubricants on the components of the sliding towing assembly. 
     When the truck and trailer are aligned—that is, when the truck is not turning—the hitch assembly resides in an aligned position. The base assembly includes a stop member which contacts the bearing boxes when the hitch assembly is in the aligned position. The stop member inhibits forward motion of the hitch assembly during deceleration when the hitch assembly is in the aligned position. The base assembly also has a second stop member which prevents rearward motion of the hitch assembly during deceleration when the hitch assembly is in the aligned position. 
     Accordingly, it is an object of this invention to provide an improved sliding towing assembly that reduces friction in the sliding mechanism. 
     It is an object of this invention to provide a sliding towing assembly that dampens noise from the hitch assembly. 
     It is an object of this invention to provide a bearing assembly that is low in cost and high in durability and reliability. 
     It is an object of this invention to provide a sliding towing assembly which remains anchored during acceleration and deceleration. 
     These and other objects of the invention will become readily apparent to those skilled in the art upon a reading of the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the sliding towing assembly shown on truck bed mounting brackets; 
         FIG. 2  is an exploded view of the sliding towing assembly showing the base assembly, bearing boxes, bearing plates, hitch assembly, capture plate and king pin; 
         FIG. 3  is a perspective view showing the base assembly with bearing boxes and bearing plates; 
         FIG. 4  is a fragmentary perspective view showing the base assembly providing a view of the stop for securing the towing assembly against fore and aft movement during straight-line movement; 
         FIG. 5  is a perspective view from below showing the hitch assembly and bearing plates; 
         FIG. 6  is a perspective view of the base assembly showing the towing, assembly in a turned position; 
         FIG. 7  shows the view from  FIG. 6  without the bearing plates; 
         FIG. 8  is a bottom view of the base assembly, as seen in  FIG. 6 ; 
         FIG. 9  is a perspective view of the hitch assembly mounted on the base assembly with the lever arm rotated and pivoted along the base assembly; 
         FIG. 10  is a fragmentary perspective view showing a vehicle and trailer attached together by the sliding hitch assembly; and 
         FIG. 11  is a perspective view showing the hitch assembly as mounted on the bushing and lever arm. 
     
    
    
     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. 
     Referring now to  FIG. 1 , a sliding towing assembly  10  includes two main parts: a hitch assembly  12  and a base assembly  14 . Hitch assembly  12  is carried by base assembly  14 . Hitch assembly  12  attaches to a trailer  20 . Base assembly  14  is mounted in the bed of a truck or similar towing vehicle  22 .  FIG. 10  shows vehicle  22 , sliding towing assembly  10  and trailer  20  in the preferred embodiment. 
     Base assembly  14  includes a frame  60 , a left guide rail  28 , a right guide rail  30 , and a channel  52 . Guide rails  28  and  30  and channel  52  are carried by frame  60 . Frame  60  is supported by a mounting bracket  24  and mounting bracket  26  which, in turn, are fixed to vehicle  22 , preferably secured to the vehicle&#39;s frame. 
       FIG. 2  shows an exploded view of sliding towing assembly  10 . Hitch assembly  12  has a latch system  16  which serves to lock onto a king pin  18  thereby securing trailer  20  to hitch assembly  12 . King pin  18  is attached to trailer  20 . A capture plate  64  may be attached to trailer  20 , and serves to hold hitch assembly  12  in fixed angular rotation with trailer  20  at the pin box. 
       FIG. 11  shows hitch assembly  12 . Hitch assembly  12  is connected to a bushing  34 . Bushing  34  is connected to and supported on a lever arm  32 . A lever arm  32  has a cam  36 . Lever arm  32  is carried by cam  36 . Bushing  34  is preferably fixed to lever arm  32  at seam  66  and to hitch assembly  12  at seam  64 , such as by welding so that hitch assembly  12  remains in rotational alignment with lever arm  32 . 
     Hitch assembly  12  is carried by base assembly  14 , as shown in  FIG. 1 , by cam  36  being carried within channel  52  which serves as a cam follower, as shown in  FIG. 4 . 
     Left guide rail  28  and right guide rail  30  flank bushing  34 , as is shown in  FIG. 7 . Guide rails  28  and  30  are preferably elongated tubes, with a generally square cross section, which attach to base assembly  14 . Guide rails  28  and  30  are positioned parallel to one another with a gap therebetween. 
     Base assembly  14  accepts a bearing block formed for ease of assembly by a left bearing box  38  and a right bearing box  40 . Bearing boxes  38  and  40  are supported on lever arm  32  and surround bushing  34  making contact therewith. Left bearing box  38  contacts left guide rail  28 . Right bearing box  40  contacts right guide rail  30 . A bearing pad formed for ease of assembly by a front bearing plate  42  and a rear bearing plate  44  rest on top of guide rails  28  and  30 . Together, bearing plates  42  and  44  form an opening  46  through which bushing  34  extends. 
       FIG. 3  shows bearing boxes  38  and  40  and bearing plates  42  and  44  positioned on base assembly  14  in the preferred embodiment with bushing  34  extending therethrough. Bearing boxes  38  and  40  and bearing plates  42  and  44  are preferably not attached to each other. Bearing boxes  38  and  40  and bearing plates  42  and  44  are preferably constructed of a durable plastic which has a low coefficient of friction. 
     Bearing plates  42  and  44  have a number of bosses  48 , best seen in  FIG. 3 , positioned around opening  46 . Hitch assembly  12  has a number of apertures  50 , as shown in  FIG. 5 . Bearing plates  42  and  44  are sandwiched between guide rails  28  and  30  and hitch assembly  12  such that bosses  48  fit into apertures  50 , thereby preventing rotation between bearing plates  42  and  44  and hitch assembly  12 . Bearing plates  42  and  44  are held between hitch assembly  12  and base assembly  14 , such that they slide with hitch assembly  12  as the hitch assembly slides along guide rails  28  and  30 , thereby reducing friction therebetween.  FIG. 1  shows hitch assembly  12  mounted on base assembly  14 . 
     Bearing plates  42  and  44  and bearing boxes  38  and  40  are designed to be removable from sliding towing assembly  10 , such as when they are worn and need to be replaced. Removal is accomplished by detaching guide rails  28  and  30  from frame  60 . With the guide rails removed, the bearing boxes can be pulled away from bushing  34 , and the bearing plates will drop away from hitch assembly  12 . New bearing plates and bearing boxes can be installed by following the removal steps in reverse. 
       FIG. 4  shows a perspective view of frame  60  and the components mounted thereon. Right guide rail  30 , right bearing box  40  and rear bearing plate  44  have been removed for illustrative purposes. Cam  36  is affixed to the underside of lever arm  32 . Cam  36  slides within a follower channel  52 . Channel  52  is of a general V-shape with a flattened portion  54  at the base of the V. When a rotational force is exerted on lever arm  32  about bushing  34 , cam  36  slides along channel  52  causing lever arm  32  and bushing  34  to slide linearly between left guide rail  28  and right guide rail  30 . Left bearing box  38  and right bearing box  40  serve as a guide as bushing  34  slides between guide rails  28  and  30 . In this way hitch assembly  12  moves along guide rails  28  and  30 , when vehicle  22  turns, thereby increasing the turning radius of trailer  20  to prevent contact between trailer  20  and vehicle  22 . Bearing boxes  38  and  40  further serve to reduce friction, dampen noise, and reduce the need for lubrication. 
     A plate  56  is mounted to frame  60  behind bushing  34  and opposite channel  52 , as shown in  FIG. 4 . Plate  56  carries a set screw  58  which in turn carries a stop  62 . When vehicle  22  and trailer  20  are aligned, with cam  36  within channel  52  at flattened portion  54 , bearing boxes  38  and  40  contact stop  62 . Bearing boxes  38  and  40  contact bushing  34 , bushing  34  is connected to lever arm  32 , lever arm  32  carries cam  36 . Stop  62  holds the lever arm assembly flush against flattened portion  54 , whereby the channel portion and stop together serve to hold lever arm  32  against longitudinal movement when vehicle  22  is axially aligned with the connected trailer, preventing hitch assembly  12  from rocking or sliding fore or aft during operation of vehicle  22 . 
     Set screw  58  allows for adjustment of stop  62  to allow for variabilities in the manufacturing process of the various components of the sliding towing assembly  10  while still ensuring flush contact between bearing boxes  38  and  40  and stop  62  when vehicle  22  and trailer  20  are aligned. Adjustment is accomplished by adjusting set screw  58  until stop  62  is brought flush with bearing boxes  38  and  40  when hitch assembly  12  is in the aligned position. 
       FIG. 6  shows lever arm  32  pivoted into the turning position. As cam  36  travels along channel  52 , lever arm  32  is guided between guide rails  28  and  30  by bearing boxes  38  and  40 , thereby lengthening the radius of rotation of the trailer to avoid contact between trailer  20  and vehicle  22 . Bearing plates  42  and  44  rotate with hitch assembly  12 , as bearing boxes  38  and  40  travel with bushing  34  longitudinally, reducing friction between hitch assembly  12  and guide rails  28  and  30  bearing boxes  38  and  40 . 
       FIG. 7  shows lever arm  32  in the turning position, with bearing plates  42  and  44  removed. As a rotational force is exerted on bushing  34  by hitch assembly  12  which is connected to trailer  20 , cam  36  travels along channel  52  which in turn causes lever arm  32  to carry bushing  34  along guide rails  28  and  30 , causing bearing boxes  38  and  40  to slide away from stop  62 . 
       FIG. 8  is a view of base assembly  14  as viewed from below. Lever arm  32  is in the turning position with cam  36  traveling along channel  52 . This view shows that as cam  36  travels along channel  52 , lever arm  32  moves away from stop  62 . By sliding lever arm  32  away from stop  62 , the turning radius of trailer  20  is elongated so as to avoid contacting vehicle  22 . Flattened portion  54  is slightly concave, forming an arcuate trough, and thus provides some resistance against cam  36  moving away from portion  54 . This concave shape helps prevent unwanted lateral sliding of the cam when the vehicle and trailer are aligned, as the concave shape will cause the cam to remain at the bottom of the trough when bumps or jolts from driving may otherwise cause the cam to rock laterally. Stop  62  braces cam  36  against portion  54  when in the aligned position to prevent longitudinal motion. 
     Hitch assembly  12  is mounted in fixed rotational contact with trailer  20 . When vehicle  22  makes a turn, trailer  20  pivots relative to vehicle  22 . Hitch assembly  12  is in fixed rotational contact with bushing  34 , bushing  34  is in fixed rotational contact with lever arm  32 . When trailer  20  pivots, rotational motion causes lever arm  32  to move cam  36  along channel  52 . Channel  52  is shaped such that as cam  36  moves laterally, it also pulls lever arm  32  longitudinally, which in turn moves hitch assembly  12  relative to base assembly  14  and away from the cab of vehicle  22 , thus allowing for a large enough turn radius to prevent trailer  20  from contacting trailer  22 . 
       FIG. 9  shows sliding towing assembly  10  in the turning position. This view shows hitch assembly  12  rotated relative to base assembly  14 , which causes cam  36  to travel along channel  52  which in turn slides hitch assembly  12  along guide rails  28  and  30 .