Abstract:
An improved fifth wheel hitch for attaching a trailer to a towing vehicle. The hitch includes an outer box support frame having two rails for mounting the trailer hitch to the towing vehicle, a spherical bearing mounted in the frame having a ball joint, and a latch assembly affixed to the spherical bearing to allow the assembly to have two degrees of movement, and a head body. The latch assembly comprises a base plate, a jaw fixed at a first elevation, and a vertically displaceable jaw. A means are provided to raise the vertically displaceable jaw above the level of the fixed jaw to allow release of the king pin latch. When the jaws are coplanar they capture the kingpin of a trailer, and safely lock the trailer to the hitch.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    I. Field of the Invention  
           [0002]    The present invention relates generally to the trailer hitch and, more particularly, to an improved fifth wheel hitch designed to better accommodate pulling forces and secure the kingpin on the tongue of a trailer to be towed by a vehicle.  
           [0003]    II. Description of the Prior Art  
           [0004]    People who live and work in urban and suburban areas often find themselves with the desire to “want to get away from it all.” They drive to secluded areas, where they can just relax. Others, desiring a more mobile lifestyle, have turned a trailer into their home. The question is, how to get their boats, campers, trailers, and the like from their busy lives to different locations.  
           [0005]    Pick-up trucks are often used to tow trailers. This creates a need for a towing hitch which can be affixed to the bed of a pick-up truck and both accommodate the pulling forces to which the trailer is exposed when traversing uneven terrains, and provide a latching mechanism which is both easy to operate as well as safe and reliable. Further, the hitch should be removable so that the truck bed can be freed of obstruction.  
           [0006]    To deal with the problem of traveling over uneven terrain with a trailer attached to a-towing vehicle, it is recognized that the hitch head should be allowed to tilt fore and aft, as well as side-to-side pivoting. The prior art has numerous examples of mechanisms to allow such tilting, most by a gimble arrangement. Allowing this movement reduces the strain placed on the latching mechanism of the hitch. Such movement however can create its own wear-and-tear on the tilting mechanism itself, creating additional repair and replacement costs. A need is therefore identified for a fifth wheel hitch assembly for coupling a trailer to a towing pick-up truck which allows for two degrees of movement of the head assembly, while at the same time reducing the friction caused by such movement.  
           [0007]    In addition to allowing the head assembly to tilt, the hitch assembly must effectively hold the kingpin of the trailer. When the towing vehicle comes to a stop, the trailer will continue to move forward, until it is interfered with by the trailer hitch. When the kingpin moves forward and is not completely surrounded by the latching mechanism, it will create a jolt along with a loud and disturbing sound. Moreover, the kingpin will wear on the unsupported area of the latching mechanism.  
           [0008]    Finally, the entire hitch assembly must not only be easily removable from the towing vehicle, but also must be easily adjustable on the truck bed of the towing vehicle. Fifth wheel hitches are typically bolted to the bed of the towing vehicle above its rear axle. However, when the trailer must be maneuvered in tight spaces, it is useful to be able to adjust fore/aft the location of the hitch assembly to a position nearer to the pickup&#39;s tailgate.  
         OBJECTS  
         [0009]    It would be advantageous to provide a fifth wheel hitch which overcomes the known problems of the prior art hitches. It is an object of the present invention to provide a fifth wheel hitch, mountable on the bed of a towing vehicle, such as a pick-up truck.  
           [0010]    It is a further object of the present invention to provide a trailer hitch which, while bolted to the bed of the towing vehicle, can be adjusted and positioned in a longitudinal direction along a pair of rails.  
           [0011]    It is another object of the present invention to provide a trailer hitch which securely holds the trailer&#39;s kingpin within the hitch assembly.  
           [0012]    It is still another object of the present invention to provide a trailer hitch which can permit the vehicle being towed to adjust to the terrain on which the towing vehicle travels.  
         SUMMARY OF THE INVENTION  
         [0013]    These objects are accomplished by the present invention which comprises a support frame having two horizontal support legs for mounting the trailer hitch to the towing vehicle, a spherical bearing mounted in the frame creating a ball joint, and a latch assembly affixed to the spherical bearing to allow the latch assembly to have two degrees of movement, and a head body to aid in guiding a kingpin into the latch assembly. The latch assembly comprises a base plate with two pivot pins extending upwardly, two pivotable jaws attached to the pivot pins, and a stationary release cam. One of the jaws is fixed at one elevation. The second jaw, can be vertically displaced so that it is either above the fixed jaw, or coplanar with the fixed jaw. A lever with a cam follower is used to elevate the vertically displaceable jaw. When a kingpin of a trailer is inserted into the head body, it is captured by the two jaws, and then locked into place. When the towing vehicle turns, or travels on uneven roads, the trailer adjusts accordingly as the base plate is attached to the spherical bearing.  
           [0014]    It is an advantage of the present invention that the latching assembly is movable along two degrees of movement namely, fore and aft and side-to-side or in pitch and yaw. These and other advantages, objects and features of the present invention will become apparent from the drawings, detailed description and claims which follow. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a side perspective view from above of a preferred embodiment of the present invention;  
         [0016]    [0016]FIG. 2 is an exploded view of the base plate, the latching assembly and the head body of the trailer hitch of the present invention;  
         [0017]    [0017]FIG. 3 is a side perspective view of an alternative embodiment of the invention having a fixed mount;  
         [0018]    [0018]FIG. 4 is a perspective view of the head body removed to more clearly show the base plate assembly and the latching assembly;  
         [0019]    [0019]FIG. 5 is a side view of the base plate and latch assembly in its released position;  
         [0020]    [0020]FIG. 6 is a cross-sectional view of the preferred embodiment showing the base plate having a center pin passing thought a spherical bearing having a vertically disposed race; and  
         [0021]    [0021]FIG. 7 is a cross-sectional view of an alternative embodiment showing the base plate having a center pin passing through a spherical bearing having a horizontally disposed race. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]    The present invention provides a fifth wheel trailer hitch. The invention is useable in a variety of towing vehicle. The invention is described in the context of a towing hitch for a 5 th  wheel trailer as a specific example for illustrative purposes only. The appended claims are not intended to be limited to any specific example or embodiment in the following description. It will be understood by those skilled in the art that the present invention may be used in conjunction with a variety of towing devices, including, but not limited to, fifth wheel hitches. Further, in the drawings described below, the reference numerals are generally repeated where identical elements appear in more than one figure.  
         [0023]    Referring to the drawings, FIG. 1 shows the preferred embodiment of a trailer hitch  10  for use in flat bed and pick-up trucks when towing a 5 th  wheel trailer. The trailer hitch has two side frame assemblies  12  and  14 , a top frame assembly  16  which joins the two side frame assemblies  12  and  14  in a parallel spaced relationship, a head body  18 , and a base assembly  20  (FIG. 2). Within the head body  18  there is a latching assembly  22  which is show in detail in the exploded view of FIG. 2.  
         [0024]    In FIG. 1, the side frame assemblies  12  and  14  each have a horizontal support leg  24  which supports two braces  26 . A mounting bracket  28  of a predetermined width having a pair of side members  30  is supported by a support leg  32  extending between the pair of braces  26  for the-mounting bracket  28  and the end portions of the horizontal support leg  24 . The mounting brackets  28  each have a pattern of apertures  34  formed therethrough. The apertures  34  are adapted to receive a fastener for connecting the side frame assemblies  12  and  14  to the top frame assembly  16 .  
         [0025]    The top frame assembly  16  has a front horizontal bar  36  and a rear horizontal bar  38  held in spaced relation by two spaced-apart cross bars  40  and  42 . Fasteners, as at  44 , are inserted into the apertures  34  of the U-shaped mounting bracket  28  and are received by the front and rear horizontal bars  36  and  38 . The pattern of apertures  34  in the mounting bracket  28  is adapted to allow selection of an elevation of the top frame assembly  16  above the horizontal support legs  24 . The head body  18  is mounted on the top frame assembly  16 .  
         [0026]    In the preferred embodiment illustrated in FIG. 1, the side frame assemblies  12  and  14  are mounted to the truck bed by a rail-latch assembly indicated generally by numeral  46 . Two guide rails  48  are adapted to be bolted to the upwardly facing surface of the bed of a towing vehicle and extend longitudinally in parallel spaced relation. The guide rails  48  each have two vertical sidewalls  50  (FIG. 1) extending perpendicularly from a base to form a guide channel  52 . The horizontal support leg  24  of the side frame assembly  12  and  14  ride on the base of the guide rails  48  and are straddled by the two sidewalls  50 . The horizontal support legs  24  of the side frame assemblies  12  and  14  are capable of sliding within the channels  52 , allowing the hitch assembly to be placed over the towing vehicles rear axles when traveling over-the-road or at a position nearer to the tailgate when backing and maneuvering in tight quarters.  
         [0027]    U-shaped clamps  54  bolted to the truck bed hold the horizontal support legs  24  of the side frame assemblies  12  and  14  down and function as a travel limiter. To fix the side frame assemblies  12  and  14  at a particular position along the rails  48  a locking structure shown in FIGS.  1  is used. The locking structure comprises a lever  56 , a latch pin  58 , and bracket  60 .  
         [0028]    The lever  56  is attached to the latching pin  58  by a link  62 . The lever  56  passes through an aperture in the bracket  60 . A coil spring  64  runs along the lever between the backside of the bracket  60  and a bolt (not shown) attached to the end of the lever  56  to urge the latch pin  58  to the right when viewed in FIG. 1. To disengage the locking structure and allow the hitch assembly to be longitudinally positioned, the user pulls the lever  56  to the left which, in turn, removes the latching pin  58  attached to the lever  56  from aligned holes in bracket  60 , U-shaped bracket  54  and rails  50 . The user then rotates the lever and the latching pin  58 . The coil spring  64  pulls the lever  56  and latching pin  58  against the bracket  54 . The rail latch assembly  46  is now able to slide to a particular maneuvering position. When the outer support frame is located at a particular position, the lock can be re-engaged. The user turns the lever  56  so that the latching pins  58  line up with a receiving hole on the bracket  54  and with a hole that is aligned with a like opening in the U-Shaped clamp bracket  54 , the sidewall  50 , and the horizontal support leg  24  of the side frame assemblies  12  and  14 . A tube runs transversely through the center of the horizontal support leg  24  and surrounds the latch pin  58  when the locking structure is engaged.  
         [0029]    In an alternative embodiment shown in FIG. 3, the side frame assemblies  12  and  14  are mounted at a fixed location on the towing truck bed. A flange plate  68  with side gussets  69  is welded to the outside surface of the horizontal support leg  24 . The flange plates  68  on each side have bolt receiving apertures for securing the side frame assembly to the bed of the towing vehicle by means of bolts, as at  70 .  
         [0030]    Once the entire hitch unit is attached to the towing-vehicle it is ready to receive the kingpin of a trailer. The kingpin latching assembly  22  of the present invention is shown in the exploded view of FIG. 2 and in a perspective subassembly view of FIG. 4 and comprises a pair of cooperating jaws  72  and  74  that must be placed in the open position shown in FIG. 4 to receive and capture the kingpin. Here, one somewhat U-shaped jaw  72  is mounted to pivot at a fixed elevation on the base plate  20 . A second, vertically displaceable U-shaped jaw  74  rests on the top surface of the fixed jaw  72 . Since both jaws are U-shaped, when the latch is open, due to a semicircular recess formed inwardly of mated edges  76  and  78 , the back leg  80  of the vertically displaceable jaw  27  is resting at an angle so that there is a gap between the front legs  82  of the two jaws. The towing vehicle can now be backed toward the trailer until the kingpin on the trailer passes into the U-shaped cut-out  84  in the top plate  85  of the head body  18 . As the trailer&#39;s kingpin then passes through the gap between the front edges  76  and  78  of the jaws and presses against the back legs of both jaws, the jaws pivot on the axis of the pivot pins  86  and  88 . When the edges of the vertically displaceable jaw  74  and the jaw  72  that is fixed in elevation becomes aligned, a return spring  90  forces the vertically displaceable jaw  74  downward so that the front edge surfaces  76  and  78  of the jaws  72  and  74  are both collinear and coplanar. The kingpin is then trapped in the circular aperture created by the two semicircular recesses formed in the front edge  76  and  78  of the jaws  72  and  74 . The cooperation between the front edges  76  and  78  of the two jaws prevent the jaws from opening up and releasing the kingpin.  
         [0031]    As a safety measure, to prevent the vertically displaceable jaw  74  from lifting clear of the fixed jaw  72  during travel, a safety pin  92  shown in FIGS.  1 - 3  is inserted into an aperture  94  on the side wall of the head body  18  and is threaded through a second aperture (not shown) which is aligned with the first aperture  94 . The safety pin  92 , when inserted into the aperture formed in the head body  18 , rests on the top of the two jaws  72  and  74 , and interferes with upward displacement of the vertically displaceable jaws  74 . The safety pin  92  is bent at a right angle at one end, and the bent tip portion  96  can be inserted into a notch  98  in an ear  99  extending from the sidewall of the head body  18  to prevent it from vibrating loose during travel.  
         [0032]    The entire latching assembly is mounted on a base plate  100  (FIG. 4). To detach the kingpin from the latching assembly, one merely needs to first remove the safety pin  92  from the head body  18 , and then turn a release handle  102 . The release handle  102  is attached to a hand lever  84  of a cam follower  106 . The cam follower  106  has a bore formed through it for receiving the pivot pin  88  therethrough. Formed into the base plate  100  is a cam surface  108 . As the cam follower  106  is rotated, the cam follower raises and falls as defined by the profile of the cam. The bottom of the vertically displaceable jaw  74  rests on the top of the cam follower  106 . When the cam follower  106  is raised, it pushes up on the vertically displaceable jaw  74  against the force of the return spring  90 , and the bottom surface of the vertically displaceable jaw  74  then slides onto the top surface of the fixed jaw  72 . The force of the kingpin acting on the front edges of the jaws  72  and  74  causes a gap there between to open, allowing the kingpin to move free of latching mechanism of the hitch unit.  
         [0033]    While the preferred embodiment discloses a cam and a cam follower arrangement for elevating the jaw  74  above the jaw  72 , those skilled in the art will appreciate that equivalent mechanical devices, such as sliding wedge or a lever mechanism can also be used.  
         [0034]    As seen in FIG. 2, in the preferred embodiment, a spherical bearing housing  110  allows the base plate  100  to accommodate towing forces to which it is exposed when traversing uneven terrain. A spherical bearing race  112  is secured in the bottom of the base plate  100 . A spherical bearing  114  is captive in the race  112  and held in place by a snap ring  113 . In this embodiment, the spherical race  112  is vertically disposed. A cylindrical center pin  116  (FIGS. 5 and 7) passes through a diametric bore formed through the spherical bearing  114 . The cylindrical center pin  116  is attached at opposed ends thereof to opposed, parallel assembly walls  118  of the head body by a pair of fasteners  120 . The base assembly with its spherical bearings  114  allows two degrees of freedom of movement, and provides a limit to the extent that the base plate  100  can tilt from side to side.  
         [0035]    A nub  111  is integrally attached to the bottom of the bearing housing  110 . A urethane filled cartridge  113  is affixed to the top of the nub  111 . The nub  111  has a threaded hole  115  which receives a bolt  115  for affixing the urethane filled cartridge  113  to the nub  111 . The urethane is of a compliance to absorb the shock created when the kingpin is received by the latch jaws  72  and  74 .  
         [0036]    In an alternative embodiment shown in FIG. 7 a vertical center pin  121  extends downward from the midpoint of the underside of the base plate  100 . The spherical race  122  is horizontally disposed. The vertical center pin  121  passes through a diametric bore formed through the spherical bearing  123 .  
         [0037]    The use of the spherical bearing assembly allows the base plate  100  to accommodate towing forces to which it is exposed when traversing uneven terrain or when, for example, one wheel of the trailer is made to ride over a speed bump, or curb, or the like. Two restraint devices  124  extend vertically downward from the underside of the base plate  100 . The restraint devices  124  are disposed proximate the front and rear edges of the base plate  100 . When the head body  18  is attached to a trailer kingpin and the trailer is turned, a rotating moment is developed about vertical pin  120 . Restraint device  124  limits the extent of rotation to the size of the apertures through which they protrude.  
         [0038]    Various alterations and modifications to the present invention will, no doubt, occur to those skilled in the towing art. It is the following claims, including all equivalents, which define the scope of the present invention.