Abstract:
A hitch for coupling a trailer to a towing vehicle includes a first coupling means for coupling with the trailer at a pivot point and a second coupling means for coupling with the trailer at a towing point. A displacing means is responsive to pivoting of the trailer with respect to the towing vehicle to move the hitch and the pivot point on the towing vehicle toward the rear of the vehicle when turning is effected and to move the hitch and the pivot point on the towing vehicle just forward of the vehicle&#39;s rear axle during normal longitudinal movement of the towing vehicle and trailer. The second coupling means is capable of transferring at least the majority of the towing force between the towing vehicle and the trailer.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a regular application of U.S. Provisional Patent Application Ser. No. 60/605,509 filed Aug. 31, 2004 and entitled, “SELF-ADJUSTING FIFTH WHEEL TRAILER HITCH”, the entirety of which is incorporated wherein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to a fifth wheel hitch assembly for use on pickup trucks and similar vehicles used to tow fifth wheel trailers and, more particularly, to a self-adjusting hitch which allows fifth wheel trailers to be towed using short bed pickup trucks and other trucks having a relatively short distance between the rear portion of the passenger compartment and the rear axle.  
       BACKGROUND OF THE INVENTION  
       [0003]     The substantial weight of the fifth-wheel travel trailer requires proper mounting of the hitch assembly relative to the axles of the towing vehicle. Where the typical pick-up truck is employed as the towing vehicle, the fifth-wheel hitch is secured in the bed of the truck above and slightly in front of the rear axle. It is desirable that the mounting not be located too far forward of the rear axle so as to avoid unnecessary bending moments about the axle. It is also desirable not to mount the hitch rearward of the axle, otherwise the towing vehicle will tend to rear off its front wheels resulting in loss of steering control.  
         [0004]     Where a long-bed truck is employed as the towing vehicle, relatively few difficulties are encountered in the proper mounting of a fifth wheel hitch. Recently, though, the popularity of the short-bed pick-up truck has grown. With such short-bed trucks there is a decreased distance between the rear axle of the truck and the cab. In such cases, and so as to provide adequate clearance between the forward portion of the trailer and the cab during turning operations, the hitch may be mounted rearward in the bed, behind the rear axle. However, as noted above, this creates an undesirable and potentially dangerous towing configuration.  
         [0005]     U.S. Pat. No. 6,308,977 to Pulliam et al. teaches a self-adjusting fifth wheel hitch assembly which allows fifth wheel trailers to be towed using short bed pickup trucks, which prevents contact between the trailer and the truck during turning operations and which provides for the proper weight distribution, relative to the rear axle, during normal longitudinal movement of the truck and trailer.  
         [0006]     The apparatus of Pulliam et al. includes a first hitch member on the trailer and a second hitch member on the towing vehicle. The hitch member on the towing vehicle is mounted on a sliding mount extending across the rear axle of the vehicle. A linkage is responsive to pivoting between the trailer and towing vehicle to move the hitch on the towing vehicle toward the rear of the vehicle when turning is effected and to move the hitch on the towing vehicle just forward of the rear axle during normal longitudinal movement of the truck and trailer.  
         [0007]     However, design of Pulliam et al, is complex, has numerous moving and linked mechanical parts and has multiple hitch members. Many of these mechanical parts responsible for the self-adjustment and pivoting aspects are also subject to the towing force exerted by the truck onto the trailer. This places additional stress on these mechanical components.  
         [0008]     What is needed is a self-adjusting fifth wheel hitch which is simple in design and does not have the above-mentioned disadvantages.  
       SUMMARY OF THE INVENTION  
       [0009]     The sliding hitch assembly according to the present invention allows fifth wheel trailers to be towed safely and conveniently using short bed towing vehicles. The present sliding hitch assembly automatically pivots at a pivot point and moves rearward away from the vehicle&#39;s cab in response to the pivotal movement between the trailer and the vehicle that typically occurs during normal driving situations such as cornering, parking, etc. The hitch assembly responds almost instantaneously to any turns, thus substantially eliminating any lag or delay. In normal operating conditions the hitch assembly and the pivot point slide rearward far enough so that the trailer will not contact the vehicle&#39;s cab. The hitch also imparts or transmits most or all of the towing force, between the towing vehicle and the trailer, via a point that is different from the pivot point.  
         [0010]     In one aspect of the invention there is provided a hitch for coupling a trailer to a towing vehicle which includes a first coupling means for coupling with the trailer at a pivot point and a second coupling means for coupling with the trailer at a towing point. A displacing means is responsive to pivoting of the trailer with respect to the towing vehicle to move the hitch on the towing vehicle toward the rear of the vehicle when turning is effected and to move the hitch on the towing vehicle just forward of the vehicle&#39;s rear axle during normal longitudinal movement of the towing vehicle and trailer. The second coupling means transfers at least the majority of the towing force between the towing vehicle and the trailer.  
         [0011]     In another aspect of the invention there is provided a hitch for coupling a trailer to a towing vehicle which includes a hitch member on the trailer for securing said trailer to the towing vehicle. A sliding mount slidably mounts said hitch member for sliding movement longitudinally with respect to the towing vehicle. A linkage is capable of transferring at least the majority of the towing force exerted between the towing vehicle and the trailer and is responsive to pivoting of the trailer with respect to the towing vehicle to move said hitch member on said sliding mount as the trailer pivots with respect to the towing vehicle. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a side view of one embodiment of the sliding fifth wheel hitch assembly according to the present invention, shown mounted on the bed of a pickup truck;  
         [0013]      FIG. 2  is a top view of the sliding fifth wheel hitch of the embodiment of  FIG. 1 ;  
         [0014]      FIGS. 3   a - 3   d  are top, side, rear and front views respectively of the guide of the embodiment of  FIG. 1 ;  
         [0015]      FIGS. 4   a - 4   c  are top, side and front views respectively of the receiver assembly of the embodiment of  FIG. 1 ;  
         [0016]      FIGS. 5   a - 5   b  are side and top views respectively of the linkage arm of the embodiment of  FIG. 1 ;  
         [0017]      FIGS. 6   a - 6   c  are side, rear and top views respectively of the linkage arm receiver of the embodiment of  FIG. 1 ;  
         [0018]      FIGS. 7   a - 7   c  are top, bottom and side views respectively of the carriage of the embodiment of  FIG. 1 ;  
         [0019]      FIGS. 7   d - 7   e  are various cross sectional views of the carriage of the embodiment of  FIG. 1 ;  
         [0020]      FIGS. 8   a - 8   c  are top, side and cross sectional views of another embodiment of a carriage having a handle;  
         [0021]      FIGS. 9   a - 9   c  are side, front and top views of a linkage arm bracket of the embodiment of  FIG. 1 ;  
         [0022]      FIGS. 10   a - 10   c  are top plan views taken from above illustrating how a fifth wheel trailer turns and moves the pivot point relative to the rear of a pickup truck&#39;s cab when mounted to the pickup truck using the sliding fifth wheel hitch assembly of the present invention (hitch assembly not shown);  
         [0023]      FIGS. 11-13  are top views of the sliding fifth wheel hitch assembly of the embodiment of  FIG. 1  as it would be situated with the trailer in the positions of  FIGS. 10   a - 10   c  respectively; and  
         [0024]      FIGS. 14-21  are various perspective views of another embodiment of the sliding fifth wheel hitch assembly according to the present invention, shown with components mounted on the bed of a pickup truck and to a fifth-wheel trailer. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]     Reference is to be had to the Figures in which identical reference numbers identify similar components.  
         [0026]     Referring to the Figures, a sliding fifth wheel hitch assembly  10  is mounted on a towing vehicle  14 , such as a pickup truck, according to common industry practice. Preferably, hitch assembly  10  is secured to the frame of the towing vehicle  14  using conventional fasteners (not shown) and wherein  14   a  is towards the front end of the vehicle  14  and  14   b  is towards the rear end of the vehicle  14 . The hitch assembly  10  is adapted to secure a fifth wheel trailer  16  to the towing vehicle  14  so that the trailer  16  can pivot relative to the towing vehicle  14  about a pivot point  18  (see  FIGS. 10   a - 10   c ).  
         [0027]     A hitch assembly  10  according to the present invention allows the pivot point  18  to slide in a rearward direction away from cab  20  and rearward from reference line A-A which is typically directly over, or in some circumstances slightly in front of, the center line of the truck axle (line A-A shown here as slightly in front of the center line of the truck axle), so that during all normal operating conditions the trailer  16  is prevented from contacting cab  20  of pickup truck  14 .  
         [0028]     Hitch assembly  10  comprises a receiver assembly  22  having an aperture  24  therein for accommodating a hitch pin  26  from a pin box or R.V. tongue  16   a  of the trailer  16 . Preferably, hitch pin  26  substantially corresponds with pivot point  18 , as can be seen in  FIG. 1 . The receiver assembly  22  is removably secured to the pin box  16   a  for pivotal movement therewith according to common industry practice. At this point any relative rotation between pin box  16   a  and receiver assembly  22  is prevented. Preferably the receiver assembly  22  is attached to the pin box  16   a  via nut-and-bolt fastener means  25  so as to firmly secure the pin box  16   a  to the receiver assembly  22 .  
         [0029]     The hitch assembly  10  further comprises a sliding mount  27  and a linkage arm  32 . Preferably the sliding mount  27  comprises a moving assembly or carriage  28  and a carriage guide  30 , the carriage  28  being constrained by the guide  30  for movement longitudinally with respect to the towing vehicle  14 . More preferably, the hitch assembly  10  also comprises a guide frame  31 . The receiver assembly  22  pivotally connects or couples to the sliding mount  27 , preferably via the carriage  28  as described in further detail below.  
         [0030]     The linkage arm  32  pivotally and operationally connects or couples between the receiver assembly  22  and the towing vehicle  14  at dual pivotable connections  32   a ,  32   b , preferably one pivotable connection at each of the linkage arm&#39;s ends as shown in  FIG. 1 . More preferably, the dual pivotable connections  32   a ,  32   b  are in the form of a ball-and-socket joint as shown more clearly in  FIG. 5 , thereby providing pivoting capability in more than one plane. The linkage arm  32  connects to the towing vehicle  14  at a linkage point  21  and connects to the receiver assembly  22  at a point other than the pivot point  18 . Preferably, the receiver assembly  22  further comprises an arm or tongue portion  23  that projects rearward from the pivot point  18  along the longitudinal axis of the trailer  16  and the linkage arm  32  connects at a point somewhere near the end of said arm portion  23 , as shown in  FIG. 1 .  
         [0031]     Thus, there are two pivotable connecting points on the receiver assembly  22 , the first point is the pivot point  18  and the second point is a point other than the pivot point  18 . The second point can also be referred to as a towing point  19  since it receives most or all of the towing force or draft during towing operations, as further described below. The towing point  19  is preferably located somewhere rearward of the pivot point  18 .  
         [0032]     In this embodiment, the linkage arm  32  operationally connects to the vehicle  14  via a receiver linkage arm receiver  33 , which in turn is fastened to the guide  30  and guide frame  31  by means of a linkage arm bracket  34 . Advantageously, the linkage arm receiver  33  and bracket  34  may be positioned along the guide  30  at a variety of positions by utilizing holes  30   d  and thereby facilitating adjustment of the linkage arm  32  and hitch assembly  10 .  
         [0033]     In another embodiment (not shown) the linkage arm  32  pivotally connects directly between the receiver assembly  22  and the towing vehicle  14 . In yet another embodiment (not shown) the linkage arm  32  pivotally connects between the receiver assembly  22  and the vehicle  14  via a bracket or other connecting means. In yet another embodiment (not shown) the hitch assembly  10  does not have guide frame  31  and the guide  30  is fastened directly to the vehicle  14  without such a frame.  
         [0034]     Advantageously, during operation all, or at least the majority, of the pulling or pushing force exerted by the towing vehicle  14  on the trailer  16  is transferred through the linkage arm  32 . More advantageously, the sliding mount  27  and its carriage  28  only bear the gravitational weight of the trailer  16  that is normally carried by the towing vehicle  14 . Even more advantageously, the carriage  28 , and any mechanical components it may have, are not subjected to all, or at least the majority, of the pulling or pushing forces between the towing vehicle  14  and the trailer  16 .  
         [0035]     These pulling or pushing forces, sometimes referred to as towing forces or draft, are instead conveyed to the trailer  16  via the towing point  19 . The pivot point  18  and the carriage  28  move along the longitudinal axis of the sliding mount  27  during operation, thereby preventing contact between the trailer and the towing vehicle&#39;s cab during turning operations and also providing proper weight distribution, relative to the rear axle, during normal longitudinal movement of the towing vehicle and trailer.  
         [0036]     The carriage  28  of the preferred embodiment comprises a trolley  28   a  having wheels  29  and bearings  29   b . Preferably the wheels  29  are made from steel. The trolley  28   a  is mounted within, and is constrained by, a longitudinal channel  30   a  within the guide  30 . Rotation of the wheels  29  and bearings  29   b , during operation of the hitch  10 , allow the carriage  28  to move longitudinally with respect to the towing vehicle  14  inside the channel  30   a . In an alternate embodiment (not shown) the carriage  28  could be slidably mounted for longitudinal movement along the guide  30 , for example by being slidably mounted on one or more rods (not shown).  
         [0037]     In this embodiment the pivotable connection between the receiver assembly  22  and the carriage  28 , at the pivot point  18 , is accomplished by a ball-and-socket joint, wherein the ball  22   a  projects from the receiver assembly  22  and the socket  28   b  is on the carriage  28 , thereby providing pivoting capability in more than one plane. Preferably, and as shown in this embodiment, the ball  22   a  mounts to the receiver assembly  22  via a neck portion  22   b  which is narrower than the diameter of the ball  22   a . More preferably, the guide  30  further comprises a longitudinal slot  30   b  which allows for movement of the neck portion  22   b  along its length, but prevents passage of the ball  22   a  through the slot. Advantageously, during normal operation the ball  22   a  is captured inside the channel  30   a  by the slot  30   b  thereby preventing the receiver assembly  22  from disengaging from the carriage  28 . Even more preferably, a widened end  30   c  of the slot  30   b  allows for insertion and removal of the receiver assembly&#39;s ball  22   a  into and out of the longitudinal channel  30   a  and the carriage&#39;s socket  28   b.    
         [0038]     Referring now to  FIGS. 8   a - 8   c  an alternate embodiment of the carriage  28  is shown. This embodiment of the carriage  28  features a handle  28   e  to facilitate alignment of the carriage&#39;s socket  28   b  with the receiver assembly&#39;s ball  22   a  during insertion of the ball  22   a  into the longitudinal channel  30   a  or to facilitate alignment of the carriage  28  and receiver assembly  22  combination underneath the pin box or R.V. tongue  16   a  during connection of the pin box  16   a  to the receiver assembly  22 .  
       Operation  
       [0039]     Referring to Figures, and during operation when the towing vehicle  14  and trailer  16  encounter a turn in the road, the trailer  16  and receiver assembly  22  pivot relative to the vehicle  14 , guide  30  and carriage  28 , which is about a vertical axis which coincides with pivot point  18 . The linkage arm  32  pivots relative to the trailer  16  and receiver assembly  22  at the towing point  19  and also pivots relative to the vehicle  14  and linkage arm receiver  33  at the linkage point  21 .  
         [0040]     Rotation of the trailer  16  and receiver assembly  22  combination, at the pivot point  18  and relative to the guide  30  and the vehicle  14 , along with the pivotal connection of the receiver assembly  22  to the to the vehicle  14  via the linkage arm  32  and its dual pivotable connections  32   a ,  32   b , at the towing point  19  and linkage point  21  respectively, activates the sliding mount  27  and causes the carriage  28  to move in a rearward direction D and away from the cab  20  of the vehicle  14 , thereby providing enough room for trailer  16  to pivot without contacting cab  20  of the vehicle  14 . Likewise, when the vehicle/trailer combination straightens out and returns from the turned position, the carriage  28  is caused to move in a forward direction, towards the cab  20  and above or in front of the rear axle center line of the vehicle  14 .  
         [0041]     In particular, when the trailer  16  turns relative to the towing vehicle  14  as shown in  FIGS. 12-13 , the receiver assembly  22  turns relative to the vehicle  14 . This rotation of the receiver assembly  22  causes the linkage arm  32  to pivot at the linkage point  21  and angle away from the longitudinal axis of the vehicle&#39;s center line, thereby causing a moment which draws the receiver assembly  22  supported by the carriage  28  away from front end  14   a  along the guide  30 . In the process, the hitch pin  26  carried by the receiver assembly  22  moves in a rearward direction away from the cab  20  of the towing vehicle  14 , thereby providing enough room for trailer  16  to pivot without contacting the cab  20  of the towing vehicle  14 . When the vehicle/trailer combination straightens out and returns from the turned position shown in  FIGS. 12-13  to the straight position of  FIG. 11 , the linkage arm  32  pivots at the linkage point  21 , angling closer towards being parallel with the longitudinal axis of the vehicle&#39;s center line, thereby causing a moment which urges the receiver assembly  22  supported by the carriage  28  towards the front end  14   a  along the guide  30 .  
         [0042]     Advantageously, the mechanical interaction of the receiver assembly  22  with the sliding mount  27  and the linkage arm  32 , and the dual pivotable connections  32   a ,  32   b  of the linkage arm  32  at the towing point  19  and at the linkage point  21 , provides the hitch assembly  10  with a significant amount of travel distance D when the trailer  16  pivots relative to the towing vehicle  14 .  
         [0043]     More advantageously, the distance along the arm portion  23  (i.e. the distance between the pivot point  18  and towing point  19 ) and the distance between the dual pivotable connections  32   a ,  32   b  of the linkage arm  32  (i.e. the distance between the towing point  19  and the linkage point  21 ) can both be varied thereby providing a greater or lesser amount of longitudinal travel D of the pivot point  18  along the sliding mount as may be desired. This can be accomplished by providing a receiver assembly  22  with a longer or shorter arm portion  23 , as may be desired, or by providing a linkage arm  32  that is longer or shorter, as may be desired. Even more preferably, the linkage arm  32  further comprises adjustable ends  32 s that are screwably adjustable (as more clearly shown in  FIGS. 5   a  and  5   b ) so as to easily vary the length of the linkage arm  32 .  
       Trailer Detachment  
       [0044]     The trailer  16  can be detached or decoupled from the hitch  10  by removing the receiver assembly  22  from the pin box  16   a . Alternatively, and in the preferred embodiment, the linkage arm  32  may be disconnected from either the receiver assembly  22  or the hitch  10 , thereby allowing the receiver assembly  22  to uncouple from the hitch and the ball  22   a  to be removed from the socket  28   b  of the carriage  28  through the widened end  30   c  of the guide  30 .  
       Other Embodiment  
       [0045]     In yet another embodiment (not shown), the hitch assembly  10  comprises a sliding mount  27  and a linkage arm  32 , as described above. However, in this embodiment, the hitch assembly  10  lacks a receiver assembly and, instead, the sliding mount  27  couples directly to the hitch pin  26  of the trailer  16 . Preferably the hitch pin  26  is in the form of a ball  22   a  having a neck portion  22   b  and socket  28   b  on the carriage  28  is suitable for engaging said hitch pin  26 .  
         [0046]     Additionally, in this embodiment, the linkage arm  32  pivotally and operationally connects between the trailer  16  and the towing vehicle  14  at the dual pivotable connections  32   a ,  32   b , similar to the connection of the linkage arm  32  between the receiver assembly  22  and the towing vehicle  14  as discussed above. However, instead of connecting to a receiver assembly, the linkage arm  32  pivotally connects to the trailer  16  at the towing point  19  via a linkage mounting means, such as a bracket, a shaft or bolt means. Preferably, this linkage mounting means is at a point some distance to the rear of the hitch pin  26 .