TECHNICAL FIELD 
     The present invention relates to latching mechanisms for a fifth wheel hitch, and more specifically to an automatically locking biased counterweight-handle latch mechanism. 
     BACKGROUND OF THE INVENTION 
     Fifth wheel hitches for towing a trailer behind a towing vehicle are well known in the art. Typically, fifth wheel hitches include a support frame for mounting the hitch to the towing vehicle. Usually, fifth wheel hitches are mounted within the bed of a pick-up truck, but can be mounted in any traction vehicle. The support frame includes a pair of transverse rails that are bolted to the bed and/or frame of the truck, rail assemblies that are releasably mounted to the transverse rails and upright assemblies mounted to the rail assemblies. A transverse cross bar typically interconnects the upright assemblies, thereby forming a head support for mounting a head assembly by means of a trunnion arrangement allowing for pivotal fore and aft movement. The head assembly includes a jaw assembly operable by means of a control handle and is specifically adapted to releasably engage and hold a kingpin of a towed vehicle. 
     One disadvantage of prior art fifth wheel hitches is that an operator must exit the vehicle to manually actuate the control handle in order to close and/or lock the hitch on the kingpin. Many hitches do not provide an indication to the operator within the vehicle when the hitch is closed and locked on the kingpin. 
     What is needed, therefore, is a fifth wheel hitch that can automatically close and lock on a kingpin. A hitch that provides an indication to an operator when the hitch is locked would assist the operator in properly using the hitch. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a latching mechanism for a fifth wheel hitch that uses a spring to bias a jaw toward a closed position and a counterweight handle that facilitates automatic closure of the hitch and provides indication thereof when a kingpin of a traction vehicle is positioned within the hitch. An embodiment of the fifth wheel hitch includes a hitch mechanism having a jaw that can be closed around a kingpin. The fifth wheel hitch also includes a latching mechanism coupled to the jaw for locking the jaw within the hitch mechanism. The latching mechanism includes a collar having a longitudinal groove formed therein, a shaft interposed within the collar, where the shaft couples the fifth wheel hitch to a handle, and a latching pin coupled to the shaft and selectively guided within the groove. The latching pin and the groove cooperate to restrict rotation of the shaft. 
     Another embodiment of the present invention provides an automatic latching mechanism for a fifth wheel hitch. The latching mechanism includes a collar having a longitudinal groove formed therein and a shaft interposed within the collar. The shaft couples the fifth wheel hitch to a handle. A latching pin coupled to the shaft is guided within the groove. The latching pin and the groove cooperate to restrict rotation of the shaft. 
     A further embodiment provides a latching mechanism for a fifth wheel hitch that includes a first member and a second member. The second member is defined by a guiding surface, and the second member is in selective engagement with the first member. One of the members is moveable between a closed position and an open position, and one of the members is coupled to a jaw of the fifth wheel hitch. The latching mechanism also includes a latching member coupled to the first member and selectively guided along the guiding surface, where the latching member and the guiding surface cooperate to restrict movement between the closed position and the open position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a fifth wheel hitch. 
         FIG. 2  is a bottom view of the fifth wheel hitch of  FIG. 1 , illustrating a jaw in a hitch closed position with many phantom components in solid lines. 
         FIG. 3  is a perspective view of a latching mechanism removed from the fifth wheel hitch of  FIG. 1 . 
         FIG. 4  is a perspective view of the latching mechanism of  FIG. 3 , taken from a different perspective as  FIG. 3 , and illustrating the mechanism in a set position. 
         FIG. 5  is a perspective view similar to  FIG. 4 , with the latching mechanism illustrated in an open, tripped position. 
         FIG. 6  is a perspective view similar to  FIG. 4 , with the latching mechanism illustrated in a closed, locked position. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 1 and 2  illustrate a fifth wheel hitch  20 . Hitch  20  includes a frame  22  that supports a pivoting jaw  24  having a kingpin engaging surface  26 , a support surface  28 , and a latching mechanism  30 . Latching mechanism  30  is attached to a handle  32  having an offset weight  34  for imparting a torque on latching mechanism  30 , as discussed below. Frame  22  is illustrated with a slot  36  formed therein. Two springs  38   a  and  38   b  ( FIG. 2  only) bias jaw  24  toward a hitch closed position illustrated in  FIGS. 1 and 2 . A moveable actuation attachment  40  is coupled to latching mechanism  30  and jaw  24  to permit pivoting of jaw  24  about a jaw pin  42 , and thus opening and closing of hitch  20 , as discussed in greater detail below. At least a portion of latching mechanism  30  is moveable in a first direction D 1 , and a second direction D 2 , as also discussed below.  FIGS. 1 and 2  also illustrate a kingpin K in proximity to fifth wheel hitch  20 . 
       FIG. 3  illustrates the latching mechanism  30  to include a first member, or shaft,  44 , a latching attachment  46 , and a collar assembly  48 . Shaft  44  includes a latching member, or latching pin,  50  extending therefrom, a locking pin  52  extending therefrom, and a handle attachment  56 . Handle  32  is coupled to shaft  44  for rotation and translation therewith by handle attachment  56 . Shaft  44  is moveable in the first direction D 1 , the second direction D 2 , a first angular direction W 1 , and a second angular direction W 2 , within the limits of collar assembly  48 , as described herein. Latching attachment  46  is rotatably coupled to shaft  44  in such a manner as to limit relative axial movement therebetween. Latching attachment  46  includes an arm  60  coupled to actuation attachment  40 . Thus, pivoting of jaw  24  between a hitch open position and a hitch closed position corresponds to movement of shaft  44  in the first and second directions D 1 , D 2 . 
     Collar assembly  48  includes a second member, or collar,  64 , having a guiding surface, or groove,  66  formed therein, and a collar bracket  68  for securement of collar  64  to frame  22 . Groove  66  includes a longitudinal portion P defined by a upper surface  70 , a lower surface  72 , an end surface  74  which intersects upper surface  70 , a notch portion  76  (shown as generally triangular in the illustrated embodiment) defining an arcuate surface  78  which intersects lower surface  72 , and an angled surface  80  which connects arcuate surface  78  with upper surface  70 . The arcuate surface  78  is generally normal to the first direction D 1 . 
     As best seen in  FIGS. 4–6 , the groove  66  further includes a latching surface  82 , which intersects upper surface  70 , and a stop surface  84  which intersects latching surface  82 . Latching surface  82  is generally normal to first direction D 1 , and stop surface  84  is generally parallel to first direction D 1 . Collectively, surfaces  70 ,  72 ,  74 ,  78 ,  80 ,  82 , and  84  act as guide surfaces for directing and limiting movement of latching pin  50 . As springs  38   a ,  38   b  ( FIG. 2  only) bias jaw  24  toward a closed position, shaft  44  is positively biased in the first direction D 1  through the connection of arm  60  and actuation attachment  40 . Thus, springs  38   a ,  38   b  exert a continuous force on shaft  44  in the first direction. 
     The operation of latching mechanism  30  will now be described. With specific reference to  FIGS. 4–6 , latching pin  50  is guidable within groove  66  between a latch open position ( FIG. 5 ), where latching pin  50  contacts end surface  74 , and a latch closed, locked position ( FIG. 6 ), where latching pin  50  contacts stop surface  84 .  FIG. 4  illustrates a set position for latching mechanism  30  where latching pin  50  bindingly contacts arcuate surface  78 . This binding contact is a result of the biasing force of springs  38   a ,  38   b  acting on shaft  44  in the first direction D 1 . With latching pin  50  in contact with arcuate surface  78 , movement of shaft  44  in the first direction is restricted, and the force exerted by springs  38   a ,  38   b  on shaft  44  is arrested. The set position of  FIG. 4  corresponds to a set position of hitch  20  where jaw  24  is between the hitch closed position and the hitch open position. In the set position, the kingpin K of a towed vehicle (not shown) is received into hitch  20  and will interfere with jaw  24  and urge jaw  24  toward the hitch open position as the kingpin engaging surface  26  of jaw  24  follows a surface portion of the kingpin K. 
     As the kingpin K is further received into hitch  20 , jaw  24  will move toward the hitch open position, as described above, thus moving latching mechanism  30  from the set position ( FIG. 4 ) to the latch open position ( FIG. 5 ), which results in shaft  44  moving in the second direction D 2 . This movement of shaft  44  in the second direction D 2  urges shaft  44  to rotate in the second angular direction W 2  as latching pin  50  is guided by angled surface  80 . Additionally, the offset weight  34  of handle  32  creates a torque that urges shaft  44  in the second angular direction W 2 , thereby urging latching pin  50  toward upper surface  70 . As the kingpin K is received further within hitch  20 , the jaw  24 , being biased by springs  38   a ,  38   b , will move toward the hitch closed position, thus moving shaft  44  in the first direction D 1 . As shaft  44  moves in the first direction D 1 , latching pin  50 , which is continually urged toward upper surface  70  by the weight of handle  32 , is guided by upper surface  70  as latching mechanism  30  moves from a latch open position ( FIG. 5 ) to a latch closed position. 
     As latching pin  50  is guided beyond upper surface  70  to latching surface  82 , shaft  44  is rotated in angular direction W 2  by the torque provided by offset weight  34  of handle  32  until latching pin  50  contacts stop surface  84  ( FIGS. 1 ,  2  and  6 ). In this latch locked, closed position, shaft  44  is arrested, or restrained, from moving in the second direction D 2  by the binding engagement between latching pin  50  and latching surface  82 . As best seen in  FIG. 1 , locking pin  52  engages the slot  36  to further inhibit shaft  44  from moving in the second direction D 2 , and handle  32  is desirably in a downward position. Thus provided, hitch  20  is in the hitch locked, closed position, as jaw  24  is restrained about the kingpin K. In this manner, an operator may view the position of handle  32  to confirm whether the hitch  20  is in the hitch locked closed position, thereby confirming that the towed vehicle is properly attached to the traction vehicle. 
     To unlock hitch  20 , an operator must rotate handle  32  in the first angular direction W 1  until latching pin  50  passes beyond latching surface  82 , thus disengaging locking pin  52  from the slot  36  and placing hitch  20  in a hitch closed, unlocked position. Handle  32  may then be pulled in the second direction D 2 , against the biasing force of spring  38 , to move jaw  24 , thus moving hitch  20  from the hitch closed, unlocked position to the hitch open position. After latching pin  50  passes beyond lower surface  72 , handle  32  is further rotated in the first angular direction W 1 , counteracting the torque provided by offset weight  34  of handle  32  that is offset from the axis of shaft  44 . Handle  32  is permitted to translate in the first direction D 1  as latching pin  50  contacts arcuate surface  78  and angled surface  80 , thereby returning latching mechanism  30  to the set position of  FIG. 4 . When the operator releases the handle  32 , the biasing force of spring  38  acting to force latching pin  50  into binding contact with arcuate surface  78  creates sufficient friction that is not overcome by the counteracting torque exerted by offset weight  34  of handle  32  that acts to urge shaft  44  to rotate in the second angular direction W 2 . 
     While the invention has been described with respect to specific examples including preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described system and techniques that fall within the spirit and scope of the invention as set fourth in the appended claims.
A latch mechanism for a fifth wheel hitch that automatically closes a jaw and locks the hitch when the hitch engages a kingpin. The latch mechanism includes a handle that is used set the latch for receiving the kingpin. The latch mechanism also includes a latching member that is biased toward a closed position and tripped in response to engagement of the kingpin with a jaw.