Patent Abstract:
A hitch assembly for coupling a trailer to a tow vehicle includes a number of assemblies, including converging links and a slide assembly, that effectively places the pivot point for the trailer ahead of the actual hitch assembly, which in turn enhances the stability of the combination tow vehicle and trailer, rendering it less susceptible to swaying or fishtailing. This is done without placing tongue weight on converging links or the slide assembly so that the hitch assembly can accommodate a larger gross trailer load.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is related to U.S. Provisional Patent Application No. 60/447,369 filed Feb. 14, 2003, from which priority is claimed. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
   Not Applicable. 
   BACKGROUND OF THE INVENTION 
   The first trailer hitches only consisted of a clevis and a pin, and later a ball mounted on the framework of a tow vehicle or a ball mount inserted into a receiver type hitch. These types of trailer hitches allowed for movement in all directions between the tow vehicle and the trailer. However, all that movement can negatively affect steering, braking, control, and overall vehicle performance. In addition, the increase in gross trailer weights over the years created the need for trailers that can handle different size weights, both large and small. 
   To accommodate different gross trailer weights, trailer hitches for light vehicles and trailers, such as autos, vans, SUV&#39;s, and pickup trucks, are generally one of four ratings, divided into Classes I-IV. For the purposes of this patent application, gross trailer weight is defined as the weight of the trailer when it is fully loaded. Ordinarily, hitches are rated for 10% of gross trailer weight to be on the tongue, referred to as the tongue weight. For the purposes of this patent application, tongue weight is defined as the weight put on a hitch ball by a trailer coupler. 
   A Class I hitch comprises a framework attached to a tow vehicle including a ball mount and ball for attaching a trailer coupler. This Class is generally rated at 2,000 lb. gross trailer weight. In addition, the ball mount can be either fixed or removable. 
   A Class II hitch is similar to Class I, except that the rating is generally 3,500 lb. Like Class I, Class II can have either a fixed or removable ball mount. 
   A Class III hitch only uses a removable ball mount. This style of hitch is known as a “hitch receiver”. In addition to ball mounts, a hitch receiver can be used with other more complicated types of mounts. 
   A Class IV hitch is similar to Class III, except it is heavier duty. This Class may be rated as high as 14,000 lbs. gross trailer weight. 
   To handle heavy trailer loads, a weight distribution hitch was invented. As trailer loads increase, tongue weight also increases. When tongue weight increases too much, it pushes down the rear of the tow vehicle causing numerous problems. To counteract this problem, the weight distribution hitch uses spring bars attached to a ball mount and a trailer frame to distribute the tongue weight among all the tow vehicle wheels and all the trailer wheels. As a result, the tow vehicle remains nearer to level from front to back while the trailer is attached. While this type of hitch is a big improvement over previous systems, it does very little to solve the problem of side-to-side movement of the trailer or sway, commonly called fishtail sway. 
   Fishtail sway is caused by the large distance between the rear axle of the tow vehicle and the hitch assembly and is aggravated by lateral forces against the vehicle caused by winds or passing vehicles. Previous attempts to solve fishtail sway involve stiffening the connection between tow vehicle and trailer by using various methods of friction. While these methods help some, none completely correct the problem. 
   Fortunately, in U.S. Pat. No. 4,722,542, hereafter referred to as the “Hensley hitch”, the sway problem is effectively corrected by forcing the hitch to turn through converging links that effectively move the pivot point between the tow vehicle and trailer to a point near the rear axle of the tow vehicle. Therefore, this design provides better steering and control of the trailer by eliminating trailer sway. While the converging links do this very well, the gross trailer weight is limited by the size and design of the converging links in &#39;542 because so much of the tongue weight is supported by the converging links. As a result, increasingly heavier tongue weights require larger links, larger bearings, larger spindles, and larger related support systems. Increasing the size of these parts also increases both the hitch weight and the cost of manufacturing. In addition, the Hensley hitch needs workable brakes on the trailer controlled from the tow vehicle. Without trailer brakes or even with surge brakes the converging links tend to move to one side or the other due to the trailer pushing on the hitch assembly when the tow vehicle brakes are applied. 
   U.S. Pat. No. 5,660,409, hereafter referred to as the “Hensley mini-hitch”, does not need workable brakes on the trailer controlled from the tow vehicle. However, the Hensley mini-hitch is still limited to use on lighter trailers with relatively light tongue weight, because the tongue weight is supported by the on a sliding ball mount. In this design, a strut holds the trailer at a constant distance from the tow vehicle while stopping. In addition, a ball mounted on a sliding mount holds the trailer at a constant distance from the tow vehicle during turns. Still, this design requires maintaining this sliding mechanism as near a zero clearance as possible. To maintain this narrow clearance, fine-tuning and maintenance is required on the sliding mount. Nonetheless, this design is not practical for use with extremely heavy tongue weight. 
   Therefore, it would be advantageous to have a trailer hitch with a converging links design which does not support tongue weight with the converging links. A trailer hitch of this type could accommodate light and heavy trailer loads without the extra weight and cost associated with larger parts. 
   SUMMARY OF THE INVENTION 
   Briefly stated, the invention is a hitch assembly comprising a hitch bar assembly coupled with a hitch receiver of a tow vehicle for transferring pulling and stopping forces to and from the tow vehicle. A hitch box assembly couples with the hitch bar assembly for transferring pulling and stopping forces to and from the hitch bar assembly, the hitch box assembly having a first pivot point. An overcenter latch assembly secures the hitch box assembly to the hitch bar assembly. A front support member pivotally connects to the hitch box assembly at the first pivot point for transferring pulling and stopping forces to and from the hitch box assembly and for pivoting during turns. A strut assembly pivotally connects to the front support member for transferring pulling and stopping forces to and from the front support member wherein the strut assembly can pivot vertically for accommodating uneven roads during driving. Also, the strut assembly includes a second pivot point. A ball mount assembly pivotally connects to the strut assembly at the second pivot point for transferring pulling and stopping forces to and from the strut assembly. The ball mount assembly laterally pivots about the second pivot point within the strut assembly during turns. The ball mount assembly includes a tail tube extending rearwardly. A ball plate assembly attaches to the ball mount assembly for transferring pulling and stopping forces to and from the ball mount assembly. The ball plate assembly includes a hitch ball for removable attachment of the trailer for transferring pulling and stopping forces to and from the trailer. A tail support assembly attaches to a trailer frame and couples with the tail tube whereby the tail support assembly restricts lateral movement of the tail tube and the ball mount assembly so the trailer remains relative to the ball mount assembly at all times. A slide assembly resides within the ball mount assembly such that forces inherent in towing the trailer are not transferred through the slide assembly. The slide assembly slides forwards and backwards to accommodate the change in radial movement of the converging links during turns. Converging links pivotally connect between the hitch box assembly at the first pivot point and the slide assembly whereby the angular position between the first pivot point and slide assembly can be varied. The converging links effectively move the pivot point between the tow vehicle and trailer forward of the hitch assembly. In addition, forces inherent in towing the trailer are not transferred through the converging links. A hanging support assembly attaches to the strut assembly including vertical links pivotally attached to the ball mount assembly for transferring tongue weight from the ball mount assembly through the strut assembly and front support member to the hitch box assembly and hitch bar assembly so tongue weight is not exerted on the converging links or the slide assembly. A jack assembly attaches between the trailer frame and the front support member for distributing tongue weight among tow vehicle wheels and trailer wheels. 
   The foregoing and other features, and advantages of the invention as well as embodiments thereof will become more apparent from the reading of the following description in connection with the accompanying drawings. 

   
     DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings which form part of the specification: 
       FIG. 1  is a perspective view of a trailer connected to a tow vehicle with a hitch assembly constructed in accordance with and embodying the present invention. 
       FIG. 2  is a top view of a hitch bar and a hitch box assembly. 
       FIG. 3  is a side view of the hitch bar and the hitch box assembly. 
       FIG. 4A  is a top view of the hitch box assembly. 
       FIG. 4B  is a side view of the hitch box assembly. 
       FIG. 5A  is a partial side view of the hitch assembly of the present invention. 
       FIG. 58  is a partial top view of the hitch assembly of the present invention. 
       FIG. 6A  is a front view of a ball plate assembly. 
       FIG. 6B  is a side view of a ball mount assembly. 
       FIG. 7A  is a partial top view of a sliding assembly. 
       FIG. 7B  is a partial side view of the sliding assembly. 
       FIG. 7C  is a partial end view of the sliding assembly. 
       FIG. 8A  is a partial top view of the hitch assembly of the present invention during straight travel. 
       FIG. 8B  is a partial top view of the hitch assembly of the present invention during a slight turn. 
       FIG. 8C  is a partial top view of the hitch assembly of the present invention during a sharp turn. 
       FIG. 9  is a partial perspective view of a tube support assembly. 
       FIG. 10  is a partial perspective view of a jack assembly. 
       FIG. 11  is a partial end view of a hanging support assembly. 
       FIG. 12  is a side view of an alternate embodiment of the invention using a roller assembly. 
       FIG. 13  is a top view of an alternate embodiment of a front support member and spring bar. 
       FIG. 14  is a side view of an alternate embodiment of the front support member and spring bar. 
       FIG. 15  is a side view of an alternate embodiment of the invention using an air bellows. 
   

   Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings. 
   DETAILED DESCRIPTION 
   The following detailed description illustrates the invention by way of example and not by way of limitation. The description clearly enables one skilled in the art to make and use the invention, describes several embodiments, adaptations, variations, alternatives, and uses of the invention, including what is presently believed to be the best mode of carrying out the invention. 
   Referring now to the drawings, particularly  FIG. 1 , a tow vehicle  1  is coupled to a trailer  4  with a hitch assembly  10  of the present invention. It will be appreciated by those skilled in the art that the tow vehicle  1  can be any conventional automobile, a van, or truck such as the pickup shown in FIG.  1 . Further, as used in the specification and the claims, the term trailer is intended to include any type of towable device or vehicle that can be pulled behind or trails a tow vehicle. The tow vehicle  1  includes rear wheels  3  which revolve about an axis X. The tow vehicle  1  includes a conventional hitch receiver  2 , which is appropriately secured to the tow vehicle  1  in any conventional or accepted manner. 
   The trailer  4  has a frame  5  which is supported on wheels  6  that revolve about a common axis Y, and the frame  5  in turn supports a trailer body  7 . The front of the frame  5  forms a so-called tongue or A-frame, in that it has side members  8  which converge forwardly and are connected at their forward ends to a coupler  9  used to secure the trailer  4  to a hitch ball  108  of the hitch assembly  10 . The coupler  9  is a generally spherical socket that opens downwardly and is sized to receive a conventional trailer hitch ball. The coupler  9  also has a conventional locking device which will close upon the hitch ball and retain it in the socket. The coupler  9  may also contain a conventional surge brake. Generally, a surge brake contains a master cylinder that is hydraulically connected through lines to brakes at the wheels of the trailer  4 . A conventional surge brake is actuated when the tow vehicle slows or stops and the forward movement of the trailer  4  urges the master cylinder against the hitch ball, which in turn, causes hydraulic actuation of the brakes at the trailer wheels. The hitch assembly  10  of the present invention can accommodate trailers employing conventional surge brakes as well as trailers employing more exotic braking mechanisms. A typical trailer also includes safety chains and an electric plug. 
   The present invention has three separate functions: 1) pulling and stopping, 2) sway controlling, and 3) load bearing. In order to better illustrate the three separate functions of the invention, the remaining description is divided into three separate sections with each section concentrating on one of the three functions of the invention. 
   Pulling and Stopping 
   As shown in  FIGS. 1-6 , for pulling and stopping the trailer  4  the hitch assembly  10  comprises a hitch bar assembly  20 , a hitch box assembly  30 , an over-center latch assembly  50 , a front support member  70 , a strut assembly  90 , and a ball mount assembly  100 . Together, these assemblies connect the tow vehicle  1  to the trailer  4  for transferring the pulling and stopping forces of the tow vehicle  1  to the trailer  4 . More importantly, none of the pulling and stopping forces are transferred through converging links  140 , which will be described below in greater detail. 
   As shown in  FIGS. 2 and 3 , the hitch bar assembly  20  is a square bar  21  that inserts into the hitch receiver  2  and projects rearwardly in a generally horizontal orientation with its longitudinal axis along the centerline of the tow vehicle  1 . The hitch bar assembly  20  fits snugly into the hitch receiver  2  with very little clearance and is secured by inserting a standard hitch pin  22  and clip  23  into corresponding through holes  24 . The hitch bar assembly  20  includes over-center latch tabs  25  welded to each side of the bar  21  at the mid-section. The tabs  25  project laterally from the bar  21  and define through holes  24 , concave recesses  26 , and roll pins  27  for coupling with the over-center latch assembly  50  to be described below. The hitch bar assembly  20  also includes stops  28  welded to the rear of the tabs  25  on all four sides of the bar  21  for mating with the hitch box assembly  30  to be described below. The stops  28  are wedges with beveled faces facing rearwardly with an angle of about 20°. 
   The hitch box assembly  30  is similar to the one disclosed in U.S. Pat. No. 4,811,967, hereby incorporated by reference, which mates with the hitch bar assembly  20 . As shown in  FIGS. 4A and 4B , the hitch box assembly  30  comprises an outer hitch box  31  and an inner hitch box  38 . The outer hitch box  31  comprises four sidewalls  32  which are joined together to form a square box-like enclosure defining an opening  33  for receiving the inner box  38 . To insure a tight fit, the inner dimensions of the outer hitch box  31  are sized to fit closely over the outer dimensions of the inner hitch box  38 . The inner hitch box  38  comprises four angular walls  39  joined to form a funnel-shaped enclosure that narrows from a front end  40  to a back end  41  for receiving the hitch bar assembly  20 . The interior dimensions of the angular walls  39  should provide enough clearance so the bar  21  of the hitch bar assembly  20  can extend to the rear of the hitch box  30  when inserted. In addition, the walls  39  are angled to match the beveled faces of the stops  28  of the hitch bar assembly  20  for proper seating. 
   The inner hitch box  38  is secured to the outer hitch box  31  by welding the front end  40  to the sidewalls  32  and welding two fillers  42  horizontally between the back end  41  and the sidewalls  32 . The inner hitch box  38  is secured inside the outer hitch box  31  so the back end  41  is raised slightly higher than the front end  40  at approximately a five-degree angle. The back end  41  is raised higher to compensate for looseness and weakness in the hitch receiver  2  when spring bars  84  are tensioned. When the spring bars  84  are tensioned, the hitch receiver  2  may angle slightly downward. Therefore, the five-degree angle serves to keep the hitch box assembly  30  nearer to horizontally level. 
   The outer hitch box  31  also comprises four front tabs  34  for attaching the over-center latch assembly  50  and four back tabs  36  for attaching converging steering links  140 , which are described below in the steering section. The front tabs  34  and back tabs  36  define respective through holes  35  and  37 . The front tabs  34  are welded at the frontward sides of the outer hitch box  31  at the top and bottom projecting laterally so the through holes  35  align. The back tabs  36  are welded to the bottom rearward sides of the outer hitch box  31  projecting laterally so the through holes  37  align. The back tabs  36  should define a gap between themselves large enough to provide a narrow clearance for inserting the converging steering links  140 . 
   As shown in  FIGS. 2 and 3 , the over-center latch assembly  50  is similar to the one disclosed in U.S. Pat. No. 4,811,967, which is used to secure the hitch box  30  to the hitch bar assembly  20 . The over-center latch assembly  50  includes a left latch  51  and right latch  52  each comprising a pair of connecting links  53 , a vertical tube  56 , a pivot pin  57 , a thrust link  59 , a latch pin  61 , and a safety pin  62 . Each connecting link  53  is a straight bar defining front through holes and back through holes. The pair of connecting links  53  are connected in parallel by hingedly attaching the pivot pin  57  between the front holes and by fixedly attaching the hollow vertical tube  56  between the back holes. The pivot pin  57  defines a transversely directed threaded bore for receiving the thrust link  59  located midway between the two connecting links  53 . The thrust link  59  is a threaded rod with a cross head  60  which inserts into the threaded bore of the pivot pin  57  so the surface of the cross head  60  is presented away from the pivot pin  57  for engaging the latch tabs  25  of the hitch bar assembly  20 . The thrust link  59  can be screwed either in or out of the threaded bore to allow for any adjustment needed to ensure a tight fit with the latch tabs  25 . To rotate the pivot pin  57  and thrust link  59  about a vertical axis, hexagonal heads  58  are attached to each end of the pivot pin  57 . The hexagonal heads  58  can be engaged by a conventional end, socket or box wrench to rotate the pivot pin  57  and thrust link  59  to engage and disengage the hitch bar assembly  20 . The left latch  51  and right latch  52  are attached to respective front tabs  34  of the hitch box  30  by inserting each latch  51  and  52  in between the top and bottom front tabs  34  so the vertical tubes  56  align with the through holes  35 . To secure both latches  51  and  52 , latch pins  61  are inserted through the front tabs  34  into the vertical tubes  56  so the latches  51  and  52  can rotate about a vertical axis. For additional security, the latch pins  61  are secured with cotter pins  63 . 
   To secure the hitch bar assembly  20  to the hitch box assembly  30  the bar  21  of the hitch bar assembly  20  inserts into the hitch box assembly  30  until the stops  28  seat against the walls  39  of the inner hitch box  38 . The latches  51  and  52  pivot from a slightly outward direction to a slightly inward position, referred to as the over-center position so the connecting links  53  rest against the roll pins  27  of the latch tabs  25 . A conventional end, socket or box wrench engages the hexagonal heads  58  of the pivot pins  57  and rotates the pivot pins  57  and thrust links  59  so the cross heads  60  engage the recesses  26  of the latch tabs  25 , also referred to as the over-center position. In this position, the hitch box assembly  30  is prevented from moving laterally or vertically with respect to the hitch bar assembly  20 . Of course, the over-center latch assembly  50  prevents the hitch box assembly  30  from pulling away from the hitch bar assembly  20 . For extra safety, the safety pins  62  are inserted into the through holes  24  of the latch tabs  25 . The safety pins  62  prevent the latches  51  and  52  from moving outwardly away from the over-center position. Of course, before anyone attempts to swing either latch  51  or  52  outwardly in order to disconnect the hitch box assembly  30 , the safety pins  62  must be removed. 
   The hitch box assembly  30  also includes an upper king pin  43  and a lower king pin  44  for pivotally connecting to the front support member  70  at a first pivot point  11 . The upper king pin  43  inserts into a through hole at the top rear of the outer hitch box  31  and fixedly attaches to the inner hitch box  38  so the upper king pin  43  protrudes upwardly out of the hitch box assembly  30 . The lower king pin  44  inserts into a through hole at the bottom rear of the outer hitch box  31  and fixedly attaches to the inner hitch box  38  so the lower king pin  44  protrudes downwardly out of the hitch box assembly  30  and is vertically aligned with the upper king pin  43 . 
   As shown in  FIGS. 5A ,  5 B,  6 A, and  6 B, the front support member  70  comprises an upper crossbar  71 , a lower crossbar  72 , side caps  73 , spring bar tubes  74 , and side support plates  75 . Both the upper crossbar  71  and lower crossbar  72  are straight rectangular tubes defining respective vertical through holes  77  and  78  and at the midsection of each tube for pivotally connecting to respective upper king pin  43  and lower king pin  44  at the first pivot point  11 . The spring bar tubes  74  are straight square tubes that weld to each end of the lower crossbar  72  so they extend rearwardly and horizontally for receiving the spring bars  84 . In addition, the spring bar tubes  74  should extend at an outward angle. When the spring bars  84  are inserted into the spring bar tubes  74 , the outward angle allows the spring bars  84  to pivotally attach to the trailer frame  5  via the jack assembly  80  to be described below. The side support plates  75  are rectangular plates defining through holes at a top end for bolting to the side caps  73 . The side support plates  75  are welded to the top edges of the spring bar tubes  74  so the plates  75  extend rearwardly and vertically, thus joining the side support plates  75  to the lower crossbar  72 . The side caps  73  are flat plates welded to each end of the upper crossbar  71  extending rearwardly and horizontally and define through holes for connecting to the side support plates  75 . The side support plates  75  also include strut pins  76  which protrude outwardly and horizontally for connecting to the strut assembly  90  to be described below. The strut pins  76  are located so they are near alignment with the center of converging steering links  140  when the hitch assembly  10  is completely assembled. 
   To attach the front support member  70  to the hitch box assembly  30 , the lower crossbar  72  is pivotally attached to the lower king pin  44  by inserting the lower kingpin  44  into the through hole  78 . The upper crossbar  71  is pivotally attached to the upper king pin  43  by inserting the upper king pin into the through hole  77 . Using bolts  79 , the side support plates  75  are fixedly attached to the side caps  73 . When assembled, the front support member  70  provides a stable pivoting connection between the hitch box assembly  30  and the strut assembly  90  at the first pivot point  11 . 
   The strut assembly  90  is an arch-shaped frame that connects the front support member  70  to the ball mount assembly  100  at a second pivot point  12  for transferring pulling and stopping forces. The strut assembly  90  also supports the hanging support assembly  150  to be described below in greater detail. The strut assembly  90  comprises two side tubes  91  and two rear caps  92 . The side tubes  91  are arched tubes with front ends that pivotally connect to the strut pins  76  of the front support member  70  so the tubes  91  can pivot vertically but are rigid laterally. Vertical pivoting of the strut assembly  90  through the tubes  91  accommodates uneven roads or drives in which the front of the tow vehicle  1  would be higher or lower than the rear of the tow vehicle  1 . The side tubes  91  extend rearwardly and horizontally so both tubes  91  arch inwardly. The rear caps  92  are rectangular plates welded laterally between the tops and bottoms at the rear ends of the side tubes  91  to complete the arch-shaped frame. The rear caps  92  include a ball mount pin  93  vertically connecting the midsections of each cap  92  for pivotally connecting to the ball mount assembly  100 . When assembled, the strut assembly  90  extends rearwardly beneath the trailer frame  5  and pivotally attaches to the rear of the ball mount assembly  100  at the second pivot point  12 . 
   The ball mount assembly  100  is a frame with a rectangular front end and a V-shaped rear end that connects the strut assembly  90  to the trailer  4  for transferring pulling and stopping forces. The ball mount assembly  100  comprises side channels  101 , vertical supports  102 , a ball plate assembly  104 , and a tail tube  109 . The two side channels  101  are C-shaped channels that extend rearwardly and horizontally parallel with each open-channel side facing inward. The rear ends of the channels  101  angle inward and are welded together forming a V-shape that mirrors the arch-shape of the strut assembly  90 . The vertical supports  102  are rectangular plates defining a plurality of through holes  103  for attaching the ball plate assembly  104  at multiple heights. The vertical supports  102  are welded vertically to the top front ends of the channels  101 . 
   As shown in  FIGS. 6A and 6B , the ball plate assembly  104  is a horizontal crossbar  105  with side supports  106  welded to each end of the crossbar  105  extending downward and a hitch ball  108  mounted to the top center of the crossbar  105 . The side supports  106  define through holes  107  for attaching to the vertical supports  102 . The tail tube  109  is a straight tube welded to the rear end of the channels  101  so the tail tube  109  extends rearwardly and horizontally for engaging a tail support assembly to be described below in greater detail. 
   To assemble, the ball plate assembly  104  is bolted to the vertical supports  102  at an appropriate height by aligning holes  107  of the ball plate assembly  104  with the appropriate holes  103  of the vertical support  102  and inserting bolts  110 . The entire ball mount assembly  100  is pivotally attached to the ball mount pin  93  of the strut assembly  90  by inserting the ball mount pin  93  through a hole at the intersection of the side channels  101 . This pivoting connection allows the ball mount assembly  100  to pivot laterally within the strut assembly  90 . In addition, the tail tube  109  couples with the tail support assembly  130  to be described below in greater detail in the steering section. To complete the assembly, the trailer  4  attaches to the ball mount assembly  100  by coupling the hitch ball  108  with the coupler  9 . Ordinarily, the typical ball-and-socket trailer hitch accommodates universal movement, but in the present invention, the trailer  4  is prevented from turning relative to the hitch ball  108  by the ball mount assembly  100  and the tail support assembly  130 . Instead, this movement is accommodated by the converging links  140  and the slide assembly  120  described below in the steering section. However, the trailer  4  is free to rock from side-to-side on the hitch ball  108  in reference to the tow vehicle  1  and the rear of the ball mount assembly  100  where the tail tube  109  slides into the tail support assembly  130 . 
   In operation, the pulling and stopping forces are transferred from the tow vehicle  1  through the hitch receiver  2  to the hitch bar assembly  20 , from the hitch bar assembly  20  to the hitch box assembly  30 , from the hitch box assembly  30  to the front support member  70 , from the front support member  70  to the strut assembly  90 , from the strut assembly  90  to the ball mount assembly  100 , and finally, from the ball mount assembly  100  to the trailer  4 . As mentioned above, none of the pulling and stopping forces are transferred through the converging links  140 . 
   Steering 
   As shown in  FIGS. 7-9 , the steering function of the hitch assembly  10  of the present invention is accomplished through a slide assembly  120 , a tail support assembly  130 , and converging links  140 . The converging links  140  are similar to the ones disclosed in U.S. Pat. No. 4,722,542 and U.S. Pat. No. 5,660,409, hereby incorporated by reference. The slide assembly  120 , tail support assembly  130 , and converging links  140  effectively move the pivot axis for the hitch assembly  10  to near the rear axle of the tow vehicle  1 . This projection of the pivot axis provides the hitch assembly  10  with good lateral stability with little or no tendency to sway or fishtail when buffeted by cross winds or when otherwise subjected to lateral forces. However, in the present design the converging links  140  do not carry any tongue weight and they do not transfer pulling or stopping forces, as described above. 
   The slide assembly  120  comprises guides  121 , slide plates  122 , crosslinks  126 , and crosslink brackets  127 . The guides  121  are plastic rectangular bars attached along the inside of the side channels  101  of the ball mount assembly  100  to act as bearing surfaces for supporting and guiding the slide plates  122 . The slide plates  122  are rectangular plates with a cutout in a front end defining two link tabs  123  and corresponding holes  124  for attaching the converging links  140 . The two slide plates  122  are welded together one on top of the other with evenly spaced spacers  125  so there is a gap between the plates  122  for receiving the guides  121 . When assembled, the slide plates  122  reside within the side channels  101  of the ball mount assembly  100  so the slide plates  122  slide forward and backward along the guides  121 . Located between the slide plates  122  is a pair of horizontal crosslinks  126  which are parallel to one another. One end of the crosslinks  126  is pivotally attached to one side of the slide plates  122  and runs crossways between the slide plates  122 . The other end of the crosslinks  126  protrudes through corresponding openings cut out of one of the side channels  101 . The protruding crosslink  126  ends are pivotally attached to a pair of crosslink brackets  127  which are welded to the outside face of the side channels  101 . 
   As described above, the rear of the ball mount assembly  100  has an extended tail tube  109  that engages the tail support assembly  130 . The tail support assembly comprises a U-bolt plate  131 , a channel  133 , and a tail bracket  135 . The U-bolt plate  131  is a rectangular plate with an angled channel tab  132  extending laterally for supporting the channel  133 . Each U-bolt plate  131  is clamped to the bottom of each trailer side member  8  using U-bolts  134  so the channel tabs  132  face inwardly and align parallel with each other. The channel  133  attaches between the channel tabs  132  so the channel  133  can be adjusted laterally for centering the tube support assembly  130  relative to the trailer  4 . The tail bracket  135  attaches to the underside of the channel  133  and extends downward so a roller  136  is parallel with the channel  133 . 
   When assembled, the tail tube  109  rests snuggly inside the tail bracket  135 . Although the roller  136  allows the tail tube  109  to move forward and backward along the longitudinal axis of the ball mount assembly  100 , the tail bracket  135  restricts any other lateral movement of the tail tube  109 . The ability to move forward and backward accommodates any such motion created by the use of surge brakes. Since the trailer  4  is rigidly attached to the tail support assembly  130 , the longitudinal axis of the trailer  4  remains parallel with the longitudinal axis of the tail support assembly  130  at all times. 
   The converging links  140  are straight links of equal length having spherical bearings  141  on each end for pivotally connecting the hitch box assembly  30  to the slide assembly  120 . The front ends of the converging links  140  are pivotally attached to the back tabs  36  of the hitch box assembly  30  with link pins  142 . The rear ends of the converging links  140  pivotally attach to the link tabs  123  of the slide assembly  120  with link pins  142 . The spherical bearings  141  allow the converging links  140  to pivot in any direction to prevent any misalignment during turns, inclines, or declines. 
   When assembled, the converging links  140  are equidistant from the centerline M and converge forwardly. The convergence is such that the links  140 , if extended forwardly, will intersect along a centerline M perhaps ahead of the rear of the tow vehicle  1 , perhaps ahead of the rear wheels  6 . When the trailer  4  is directly behind the tow vehicle  1 , the links  140  are symmetrically positioned. When the trailer  4  shifts to one side or the other during turns, the convergence intersection transfers to points which are closer to the hitch box assembly  30  and offset from the centerline M. Together, the converging links  140  and slide assembly  120  effectively move the pivot axis for the hitch assembly  10  to near the rear axle of the tow vehicle  1 . 
   The relative relationship of the elements of the hitch assembly  10  when the tow vehicle  1  and trailer  4  are negotiating turns are shown in  FIGS. 8A ,  8 B, and  8 C. As the tow vehicle  1  turns relative to the trailer  4 , the hitch bar assembly  20  and hitch box assembly  30  necessarily move in the direction of hitch receiver  2  on the tow vehicle  1 . The front support member  70  and strut assembly  90  pivot at the first pivot point  11 . Simultaneously, the converging links  140  pivot to allow turning while maintaining the effective hitch pivot axis near the rear of the tow vehicle  1 . As the individual links  140  pivot, the relative radius of the links  140  shorten drawing the slide assembly  120  forward towards the hitch box assembly  30  and the ball mount assembly  100  pivots at the second pivot point  12 . As the tow vehicle  1  turns sharper, the ball mount assembly  100  will pivot at the second pivot point  12  until it rests nearly against the strut assembly  90 . As mentioned above, the trailer  4  remains parallel with the longitudinal axis of the ball mount assembly  100  because the trailer  4  is rigidly attached to the ball mount assembly  100  and the tail support assembly  130 . Since ball mount assembly  100  with the hitch ball  108  and trailer  4  attached thereto, are held in place at the second pivot point  12  by strut assembly  90 , the trailer  4  remains a predetermined distance away from the tow vehicle  1  (e.g. the length of the strut assembly minus the length of the ball mount assembly plus a small change in the radius of ball mount assembly as it moves side-to-side). Therefore, braking of the tow vehicle even without the use of good trailer brakes doesn&#39;t allow pressure to be exerted on the converging links. 
   In this way the converging links  140  steer the trailer  4  and the sliding movement of the slide assembly  120  accommodates the change in radial movement of the converging links  140  during turns. However, neither the slide assembly  120  nor the converging links  140  carry any of the tongue weight as in previous designs. Instead, the tongue weight is carried on a hanging support assembly  150  to be described below in the weight carrying section. As a result, the present invention allows for more tongue weight without adding to the cost and weight by increasing the size of the converging links and all associated components as in previous designs. In addition, adjustable blocks are not needed to keep the side movement of the ball mount assembly  100  to near zero clearance. Instead, the present invention uses two parallel crosslinks  126  which eliminate the need for fine-tune or maintenance as in previous designs. 
   Weight Carrying 
   Generally, the present invention can handle greater gross trailer loads than previous designs. In the present invention, this is accomplished by not carrying any tongue weight with the converging links  140 , as mentioned above. Instead, the hanging support assembly  150  carries the tongue weight, which keeps the converging links  140  approximately level with the hitch assembly  10  at all times. In addition, spring bars  84  and the jack assembly  80  distribute the tongue weight among all the tow vehicle wheels  3  and all the trailer wheels  6 . As a result, the present invention relates to Class III or heavier rated hitch systems. 
   The hanging support assembly  150  comprises a support frame  151  and a pair of vertical links  154 . The support frame  151  is an arch-shaped frame including legs  152  that rigidly attach vertically to the front end of the strut assembly  90  and a crossbar  153  connecting the legs  152 . The support frame  151  should be attached directly over the side supports  106  of the ball plate assembly  104  with the crossbar  153  parallel with the front support member  70 . The vertical links  154  are straight links with spherical bearings  155  attached at each end for connecting the support frame  151  to the side channels  101  of the ball mount assembly  100 . Top ends of the vertical links  154  pivotally connect to the crossbar  153  so the vertical links  154  hang parallel to each other. Bottom ends of the vertical links  154  pivotally connect to respective side channels  101 . The spherical bearings  155  allow the ball mount assembly  100  to pivot during turning as described above. When assembled, the tongue weight placed on the ball mount assembly  100  by the trailer  4  is transferred to the hanging support assembly  150  via the vertical links  154 . The hanging support assembly  150  transfers the weight through the strut assembly  90  and front support member  70  to the hitch box assembly  30  and hitch bar assembly  20 , which are supported by the hitch receiver  2 . As will be described below, the springs bars  84  and jack assembly  80  distribute the weight among all the tow vehicle wheels  3  and all the trailer wheels  6 . As a result, the tongue weight is transferred to the tow vehicle  1  and the trailer  4  without placing any tongue weight on the converging links  140 . 
   Those skilled in the art will recognize that alternative embodiments may be used in place of the hanging support assembly  150  to carry the tongue weight. For example,  FIG. 12  illustrates a roller assembly  160  for supporting the tongue weight on the hitch assembly  10 . The roller assembly  160  comprises a pair of roller supports  161 , a pair of rollers  163 , a C-channel  166 , and a channel support  169 . Each roller support  161  is a flat plate that welds to the bottom of a respective side channel  101  of the ball mount assembly  100  so that roller tabs  162  extend forwardly. The rollers  163  pivotally attach to each roller tab  162  so they can engage the C-channel  166 . The C-channel  166  is welded between the side tubes  91  of the strut assembly  90  with the opening of the C-channel  166  facing the rollers  163  for engagement. The C-channel  166  includes a spacer  167  and a wear plate  168  along an inner bottom surface. When assembled the rollers  163  fit inside the C-channel  166  so the rollers  163  can roll back and forth along either the wear plate  168  or the top inner surface of the C-channel  166 . The channel support  169  attaches to the midsection of the C-channel  166  to provide additional support to the C-channel  166 . The channel support  169  includes two tabs  170  that respectively attach to the top and bottom of the C-channel  166 . A bolt  171  and spacer  172  connect the two tabs. During operation, tongue weight is transferred from the hitch ball  108  and ball mount assembly  100  through the roller assembly  160  to the front support member  70 . As described above, the tongue weight then transfers from the front support member  70  to the hitch box assembly  30  and hitch bar assembly  20 , which are supported by the hitch receiver  2 . Finally, the springs bars  84  and jack assembly  80  distribute the weight among all the tow vehicle wheels  3  and all the trailer wheels  6 . As a result, the tongue weight is transferred to the tow vehicle  1  and the trailer  4  without placing any tongue weight on the converging links  140 . 
   As mentioned above, the spring bars  84  are inserted into the spring bar tubes  74  located on the front support member  70  extending rearwardly and horizontally at an outward angle so they can attach to the trailer frame  5  via the jack assembly  80 . The outward angle positions the rear ends of the spring bars  84  into near alignment with the side members  8  of the trailer&#39;s A-frame. The spring bars  84  also slope downward toward the rear to allow for tensioning. 
   The jack assembly  80  comprises a pair of jacks  81 , jack brackets  82 , spring bar links  83 , and the spring bars  84 . The jack brackets  82  are L-shaped brackets secured to the top of the side members  8  of the trailer  4  by the same U-bolts  134  used to secure the U-bolt plates  131 . However, the jack brackets can be secured by any other conventional means, such as welding or independent U-bolts. The jacks  81  are vertically welded to the jack brackets  82  so each jack  81  resides in a recess of the U-bolt plate  131 . The spring bars  84  are attached to the jacks  81  with the spring bar links  83 . The upper end of each spring bar link  83  is pivotally attached to each jack  81  and the lower end of the each link  83  is pivotally attached to each spring bar  84 . Consequently, the jacks  81  can tension the spring bars  84  while still allowing pivotal movement during turns. The jacks  81  should be cranked until appropriate tension is applied to the spring bars  84 . Spring bars have long been used in conjunction with trailer hitches to achieve better weight distribution among all the tow vehicle wheels and all the trailer wheels, and the principle will therefore not be described in more detail here. 
   Changes can be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. For example, the spring bars  84  and front support member  70  can be modified to accommodate different shapes and sizes of trailer frames. In one alternate embodiment shown in  FIGS. 13 and 14 , the front support member  70  includes inner plates  180  parallel to the side support plates  75 . The plates  180  and  75  should be spaced appropriately for receiving the spring bars  84 . In this alternate embodiment, the spring bars  84  are round L-shaped bars. The spring bars  84  are pivotally attached to bushings  181  located between the plates  180  and  75 . Using an adjustable T and washers  182  attached to the plates  180  and  75 , the spring bars  84  can pivot to accommodate different shape and sizes of trailer frames. It should be noted that in this alternate embodiment, the spring bar tubes  74  of the front support member  70  described above are not included. 
   In another alternate embodiment shown in  FIG. 15 , the jack assembly  80  is replaced with an air bellows assembly  190  for distributing the tongue weight among all the tow vehicle wheels  3  and all the trailer wheels  6 . In this embodiment, the spring bars  84  attach to a bellows bracket  191 . The bellows bracket  191  pivotally attaches between the front support member  70  and a shock absorber  192 . The shock absorber pivotally attaches to the trailer frame  6 . The bellows bracket  191  rests on an adjustable air bellows  193 . In operation, the air bellows  193  adjusts similar to the jacks  81  of the first embodiment to equalize the tongue weight.

Technology Classification (CPC): 1