Abstract:
Jaws of a fifth wheel hitch have front arms that overlap each other. The jaws are linked for simultaneous movement at the same speed and corresponding positions when closing around the kingpin, and a pawl holds the jaws closed. A handle moves a pawl to unlock the hitch to allow ejection of the kingpin, and once the jaws are open the pawl holds them open. A position indicator is linked both to the handle and to one of the jaws. The position indicator moves between three indications: locked, unlocked and open.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    None. 
       BACKGROUND OF THE INVENTION 
       [0002]    Fifth wheel hitches are well-known in the hitch industry and are designed for carrying much heavier loads than the typical ball hitch can handle. The fifth-wheel trailer includes a downwardly-facing pin, called a kingpin, which extends generally vertically on the leading tongue of the trailer. The fifth wheel hitch includes a large, flat skid plate shaped similar to a horseshoe. The kingpin is secured within the opening of the horseshoe by one or two jaws. The jaw(s) hold the position of the kingpin while allowing allow pivoting to accommodate turns, hills, etc. Various control lever structures have been used for moving the jaws to release the kingpin. Examples of such a fifth-wheel hitch are disclosed in U.S. Pat. Nos. 6,846,000 and 6,935,650, 7,475,899, 7,543,837 and 7,584,982, each incorporated by reference. 
         [0003]    The fifth wheel hitch must be strong to securely engage the trailer, minimizing the possibility of breakage or of any way the trailer could inadvertently come loose. At the same time, the fifth wheel hitch should be simple to operate, so the operator has no difficulty in intentionally engaging and disengaging the trailer. Operation of the controls of the fifth wheel hitch to lock and release the jaw(s) should not require the application of excessive force or torque. The average operator of a fifth-wheel or gooseneck hitch is not young, such as over 55 years old, who is perhaps not as strong and nimble as he or she once was. The controls of the hitch should be readily accessible by the operator, without requiring too much climbing or bending to access. The fifth wheel hitch should preferably be mechanically operated, so there is no possibility of a loss of power preventing operation of the hitch. 
         [0004]    Towing conditions are such that hitches are normally subjected to considerable amounts of dirt and grime, and treated very roughly. The hitch should readily withstand such conditions. The hitch must be robust and reliable, to last for carefree operation over the life of at least one vehicle, and possibly over the life of several vehicles, despite the fact that the hitch will likely be openly exposed to weather over its years or decades of use. As much as possible, the hitch should also have minimal cost and expense in manufacturing and assembly. In keeping with these objectives, further improvements to fifth wheel hitch designs are possible. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    The present invention is in part directed at fifth wheel hitches having at least two jaws, and involves the realization that such jaws should be constructed and linked to jointly close more convincingly around the kingpin. In one aspect, the jaws of the fifth wheel hitch overlap each other and move without changing elevation, so there is no vertical gap that the kingpin is trying to work its way through and no perception that roadway vibration could unseat the jaws relative to each other. In another aspect the jaws are linked for simultaneous movement at the same speed and corresponding positions when closing around the kingpin. In a separate aspect, a position indicator is linked both to a handle for the fifth wheel hitch and separately linked to at least one jaw. The position indicator moves between three indications (locked, unlocked and open), even if the handle and/or the jaw does not move between two of those three indications. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a perspective view of a preferred embodiment of the fifth wheel hitch of the present invention. 
           [0007]      FIG. 2  is a top view of the fifth wheel hitch of  FIG. 1 , with the front of the fifth wheel hitch at the top of the page. The terms “front”, “rear” or “behind”, “passenger&#39;s side” (for U.S.) or “right”, and “driver&#39;s side” (for U.S.) or “left”, for all uses herein, all refer to the designed forward direction of travel to the towing vehicle. 
           [0008]      FIGS. 3 and 4  are rear elevation and passenger side views of the fifth wheel hitch of  FIGS. 1 and 2 . 
           [0009]      FIG. 5  is an exploded top front perspective view of the fifth wheel hitch of  FIGS. 1-4 . 
           [0010]      FIG. 6  is an exploded rear bottom perspective view of the head assembly of the fifth wheel hitch of  FIGS. 1-5 . 
           [0011]      FIG. 7  is a bottom view (looking up), in partial cross-section, of the assembled head assembly of  FIGS. 1-6 , with the front of the hitch at the bottom of the page. 
           [0012]      FIGS. 8-10  are views similar to  FIG. 7 , also showing the kingpin in cross-section, showing operation of the fifth wheel hitch of  FIGS. 1-7 . 
           [0013]      FIGS. 11 and 12  are perspective view of the driven (driver&#39;s side) jaw of the fifth wheel hitch of  FIGS. 1-7 . 
           [0014]      FIGS. 13-16  are top (plan, with the front of the jaw at the top of the page), front, rear (elevation) and side views of the driven (driver&#39;s side) jaw of  FIGS. 11 and 12 . 
           [0015]      FIGS. 17 and 18  are perspective view of the driving (passenger&#39;s side) jaw of the fifth wheel hitch of  FIGS. 1-7 . 
           [0016]      FIGS. 19-22  are top (plan, with the front of the jaw at the top of the page), front, rear (elevation) and side views of the driving (passenger&#39;s side) jaw of  FIGS. 17 and 18 . 
       
    
    
       [0017]    While the above-identified drawing figures set forth a preferred embodiment, other embodiments of the present invention are also contemplated, some of which are noted in the discussion. In all cases, this disclosure presents the illustrated embodiments of the present invention by way of representation and not limitation. Numerous other minor modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of this invention. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    The present invention can be provided as part of a fifth wheel hitch  20  as shown in  FIGS. 1-5 , which can be mounted in the bed of a pick-up truck (not shown) to support the weight of a kingpin type trailer (not shown) over the rear axle of the pickup truck. The fifth wheel hitch  20  includes a head assembly  22  mounted to a base support structure  24 , with the base support structure  24  shown in an exploded view in  FIG. 5 . The base support structure  24  could have widely varying constructions, but in the preferred embodiment includes two mounting channel weldments  26  that include tabs  28  on their feet  30  for mounting into rails (not shown) secured on the bed of the pickup truck (not shown). A crossmember weldment  32  is secured by bolts  34  between the two mounting channel weldments  26 , enabling a user to select the elevation of the crossmember weldment  32  relative to the pickup bed. 
         [0019]    The head assembly  22  can pivot in several different degrees of freedom relative to the crossmember weldment  32 , such that the head assembly  22  when towing a kingpin trailer can pivot as the trailer accommodates turns, hills, etc. In the preferred embodiment, the pivoting is provided with a head support yoke  36 , best seen in  FIG. 5 . The head support yoke  36  has a central opening  38 , and is retained in the crossmember weldment  32  by a torsion pin weldment  40  extending through the central opening  38  in the yoke  36  as well as through an opening  42  in the crossmember weldment  32 . The torsion pin weldment  40  is secured to the opening  42  in the crossmember weldment  32  using a bolt  44 , enabling assembly and disassembly of the yoke  36  to the crossmember weldment  32  as needed. The shape of the torsion pin weldment  40  mates with the shape of the corresponding central opening  38  in the yoke  36  as well as the shape of the opening  42  in the crossmember weldment  32 . In the preferred embodiment, these shapes are square, but the central opening  38  in the yoke  36  is larger than the size of the torsion pin weldment  40 . A torsion insert  46  is placed around the torsion pin weldment  40  within the central opening  38  in the yoke  36 , compression/twisting of which enables the yoke  36  to pivot about and move somewhat relative to the axis  48  of the torsion pin weldment  40 . Two wear plates  50  are positioned on either side of the yoke  36 , between the yoke  36  and the crossmember weldment  32 , so the pivoting of the yoke  36  about the axis  48  creates minimum friction and wear. 
         [0020]    At a top end of the yoke  36  extending above the crossmember weldment  32 , the yoke  36  includes two shaped ears  52  defining a second pivot axis  54  for the head assembly  22 . Like the torsion pin weldment  40 , the ears  52  in the preferred embodiment are square and surrounded by torsion inserts  56 . These torsion inserts  56  are received in mating recesses  58  (best seen in  FIG. 6 ) in the head assembly  22 . Rather than fully encircling the ears  52 /torsion inserts  56 , the recesses  58  only contact three of the four sides of the torsion inserts  56 , so the head assembly  22  can be easily attached to and removed from the yoke  36 . If desired to reduce the number of different parts, the ears  52  may be the same size and shape as the torsion pin weldment  40 , and the recesses  58  may be the same size and shape as the opening  38 , so the torsion inserts  56  can be identical parts to torsion insert  46 . Attachment pins  60  extend through mating holes in the yoke  36  and holes  62  in the head assembly  22  to secure the head assembly  22  to the yoke  36  in the vertical direction. In the preferred embodiment, each attachment pin  60  includes a slanted end which resides in a slot  64  in the yoke  36 . Each attachment pin  60  is held in place by a cotter pin clip  66 . While the extension of the attachment pins  60  through the ears  52  and the holes  62  in the head assembly  22  largely prevents vertical or horizontal movement of the head assembly  22  relative to the yoke  36 , compression/twisting of the two torsion inserts  56  enables the head assembly  22  to pivot somewhat about the axis  54  of the ears  52 . The attachment pins  60  and cotter pin clips  66  allow for quick attachment and detachment of the head assembly  22  relative to the base support structure  24 . 
         [0021]    Other than the wear plates  50  and the torsion inserts  46 , all the components of the base support structure  24  can be formed of a suitably strong metal such as steel (ASTM A36 with a powder coat finish, or standard plated alloy steel nuts and bolts) or equivalent materials. The wear plates  50  should be formed of a material with better bearing/wear properties, such as a strong polymer providing a low friction surface, in the preferred embodiment formed of AR Glass-filled ultra-high-molecular-weight polyethylene. The torsion inserts  46 ,  56  should be formed of a resilient, compressible material, such as rubber or more preferably polyurethane. 
         [0022]    An exploded view of the various component parts of the head assembly  22  is shown in  FIG. 6 . The head assembly  22  primarily includes a full head weldment  68 , two jaws  70 ,  72 , a handle  74 , a pawl  76 , and a hitch position indicator  78 . The full head weldment  68  provides the horseshoe shaped skid plate  80  as generally known in the art. The opening between the sides of the skid plate  80  defines a midplane  82  (shown in  FIG. 7 ) of the hitch  20  and defines the direction that the kingpin  84  travels during hitching and unhitching, which is open to the rear of the towing vehicle. (The terms “rear” and “front” for all uses herein all refer to the designed forward direction of travel to the towing vehicle). The full head weldment  68  also provides structure underneath the skid plate  80  that allows for attaching and supporting the other components relative to the skid plate  80  and above the base support structure  24 . In the preferred embodiment, the structure under the skid plate  80  for attaching the skid plate  80  above the base support structure  24  includes two legs  86  which define recesses  58  for receiving the torsion inserts  56 , as well as two pin openings  62  for receiving the attachment pins  60 . The structure under the skid plate  80  for attaching and supporting the other head components relative to the skid plate  80  includes a lower mounting plate  88  (shown in  FIG. 6 ) spaced relative to the underneath surface of the skid plate  80 , a handle lock plate  90 , and an indicator axle  92  (shown in  FIG. 7 ). 
         [0023]    Each jaw  70 , 72  is pivotally attached to the full head weldment  68  by a flat socket head cap screw  94  and nut  96 , extending through corresponding holes in the full head weldment  68  and corresponding holes  98  (best seen in  FIGS. 11-13  and  16 - 18 ) in each jaw  70 ,  72 . Thus, as shown in  FIGS. 1 ,  5  and  6 , the right (passenger side) jaw  70  pivots about a right jaw pivot axis  100 , and left (driver side) jaw  72  pivots about a left jaw pivot axis  102 . In the preferred embodiment, each jaw  70 ,  72  is about 30 mm thick. 
         [0024]    The jaws  70 ,  72  provide several features which are beneficial over the prior art. A first such feature involves the portion of the jaws  70 ,  72  which hold the kingpin  84  in the towing position. As best shown in  FIGS. 6-22 , each jaw  70 ,  72  includes a locking arm  104  which wraps around past the midplane  82  of the skid plate  80 , i.e., the left jaw  72  extends around to the right of the midplane  82  and the right jaw  70  extends around to the left of the midplane  82 . Each of these locking arms  104  is substantial and strong, preferably strong enough to unilaterally support the towing load of the kingpin  84 . In the preferred embodiment with the jaws  70 ,  72  formed of ASTM A36 steel, the locking arms  104  are about 15 mm thick at the midplane  82 . 
         [0025]    Rather than have a horizontal or vertical interface between the two locking arms  104  behind the kingpin  84 , the interface between the two locking arms  104  behind the kingpin  84  extends at an angle  106 , called out in  FIGS. 14 ,  15 ,  20  and  21 . In the preferred embodiment, this angle  106  is about 15°, such that the locking arms  104  vary in height/thickness from about 20 mm to 10 mm in the active area of the jaw  70 ,  72  in the region behind the kingpin  84  and within the opening in the skid plate  80 . By having the interface at an angle  106 , even if one or both jaws  70 ,  72  are slightly out of alignment when coming together from the open position to the locked position, there is no possibility of a collision between the jaws  70 ,  72  prior to the jaws  70 ,  72  being fully closed. The locking arms  104  are about 30 mm deep at the midplane  82  behind the kingpin  84 , i.e., each have an area of about 450 mm 2  when taken at the midplane  82  behind the kingpin  84 . The preferred jaws  70 ,  72  have a curved plan view outer profile (best shown in  FIGS. 13 and 19 ), and the depth of the locking arms  104  varies from about 30 mm to 20 mm in the active area of the jaw  70 ,  72  in the region behind the kingpin  84  and within the opening in the skid plate  80 . 
         [0026]    As best seen in  FIGS. 11 ,  12 ,  17  and  18 , each jaw  70 ,  72  has a generally semi-circular contact surface  108  with the kingpin  84  in the locked position. In the preferred embodiment, the contact surface  108  of each jaw  70 ,  72  has a height of 15 mm in front of the kingpin  84 , and has the full 30 mm height throughout the contact surface  108  behind the kingpin  84 , with each contact surface  108  terminating just before the midplane  82 . The locking arms  104  extend away from this contact surface  108 , such that the locking arms  104  do not contact the kingpin  84  at all while the hitch  20  is locked around the kingpin  84  during ordinary use. Should the closed position of the jaws  70 ,  72  become at all “sloppy” during years of use, the locking arms  104  may contact the kingpin  84  and the kingpin  84  has no possibility of wedging between contact surfaces  108  of the two jaws  70 ,  72  to further force the jaws  70 ,  72  open. Regardless of the presence or absence of contact between the locking arms  104  and the kingpin  84  when the hitch  20  is in the locked position, the locking arms  104  play an important role in providing a real and consumer-perceived level of safety. The locking arms  104  fully wrap around the kingpin  84  (looking from the rear like two fingers enclenched around the kingpin  84 ) with two different locking arms  104  preventing any possibility that the kingpin  84  could escape from the skid plate opening. In a plan view, each jaw  70 ,  72  in the closed position takes the shape of a letter “C” in sign language, such that jaws  70 ,  72  resemble two hands gripping around the kingpin  84 . Even if one jaw should catastrophically fail or open, the other jaw could single-handedly lock the kingpin  84  in towing position. This double layer of safety is both real (due to redundancy in the case of part failure) and readily perceived by the user as providing a stronger hitch product (even though, in ordinary operation, the locking arms  104  never contact or bear any of the stress from the kingpin  84 ). 
         [0027]    As an alternative arrangement for the jaws  70 ,  72 , the locking arms  104  can extend tighter to the kingpin  84  and make up part of the contact surface with the kingpin  84 . In such an arrangement, a portion of the contact surface of one closed jaw would be directly underneath a portion of the contact surface of the other closed jaw, and each contact surface would extend behind the kingpin  84  past the midplane  82  in the closed position. In the preferred arrangement, however, the jaws  70 ,  72  do not have to rotate quite as far to release the kingpin  84 . Moreover, in the preferred arrangement, the contact surfaces  108  (which cannot extend more than 180° around the kingpin  84  for each jaw  70 ,  72 ) can collectively contact about 360° around the kingpin, rather than having a portion in front of the kingpin  84  without contact. 
         [0028]    A second beneficial feature over prior art jaws is provided on the other end of the jaws  70 ,  72 . One of the jaws  72  is a driven jaw, and includes a projection  110 . The other jaw  70  is a driving jaw and includes a slot  112  which receives this projection  110 . Both the projection  110  and the slot  112  are at the elevation where the jaw contacts the kingpin  84 . The coupling of the projection  110  into the slot  112  causes the driving jaw  70  to push/pull the driven jaw  72  with it, such that neither jaw  70 ,  72  can pivot about its pivot point  100 ,  102  without the other jaw  70 ,  72  simultaneously pivoting. 
         [0029]    As best shown in  FIGS. 17 and 19 , the slot  112  is not linear, but rather is arcuate. By having an arcuate slot  112  with an appropriately shaped arc, the angular location of each jaw  70 ,  72  is maintained at a generally equivalent and opposite position to the other jaw  70 ,  72 , i.e., if driving jaw  70  is at a 5° open position, then driven jaw  72  is at a 5° open position; if driving jaw  70  is at a 10° open position, then driven jaw  72  is at a 10° open position, etc. The simultaneous and equal movement of the jaws  70 ,  72  achieved by the present invention reinforces the understanding of the consumer that both jaws  70 ,  72  work equally to strongly hold the kingpin  84  in the closed position. 
         [0030]    A third beneficial feature over the prior art jaws relates to the pawl locking arrangement of the present invention. The pawl  76  is pivotally attached to the full head weldment  68  by a flat socket head cap screw  114  and nut  116  (shown in  FIG. 6 ), extending through a corresponding hole in the full head weldment  68  and a corresponding hole  118  in the pawl  76  as well as through a pawl spacer  120 . Thus, the pawl  76  pivots about a pawl pivot axis  122 . A torsion spring  124  gently biases the pawl  76  toward an open position. 
         [0031]    As best shown in  FIGS. 7-10 , movement of the jaws  70 ,  72  is controlled by a jaw tension spring  126  and the pawl  76 . The tension spring  126  biases the driving jaw  70  (and, through the projection/slot coupling, the driven jaw  72 ) toward the open position. While the pawl  76  is in the locked position of  FIGS. 7 and 8 , however, pawl  76  bears and interferes against a pawl stop surface  128  (called out in  FIGS. 9 ,  11 - 13  and  15 ) of the driven jaw  72  to prevent both jaws  70 ,  72  from opening. In the closed position of  FIGS. 7 and 8 , the pawl stop surface  128  is in the shape of an arc of a circle centered on the pawl pivot axis  122 , i.e., centered on the bolt  114 . When the pawl  76  is fully removed from contacting the pawl stop surface  128  as shown in  FIG. 9 , the jaw tension spring  126  biases both jaws  70 ,  72  open. The ability of the jaws  70 ,  72  to open then depends upon the kingpin  84 , i.e., the weight of the trailer and force of the kingpin  84  may prevent the jaw spring  126  from ejecting the kingpin  84  from the hitch  20  until the towing vehicle drives away from the trailer, but as soon as the kingpin  84  is out the spring  126  causes the jaws  70 ,  72  to open. 
         [0032]    Movement of the pawl  76  is controlled by the handle  74 , which interacts with the pawl  76  through a link  130 . For ease of manufacture and assembly, the handle  74  is provided in two parts, including an angular linkage portion  132  received in a tubular portion  134 . The angular linkage portion  132  is rigidly joined to the tubular portion  134  with two bolts  136  and nuts  138 , with one of the bolts  136  (best shown in  FIG. 6 ) doubling as a tension spring anchor. The handle  74  (including both the angular linkage portion  132  and the tubular portion  134 ) is pivotally attached to the full head weldment  68  by a flat socket head cap screw  140  and nut  142 , extending through a corresponding hole in the full head weldment  68  and a corresponding hole  144  in the handle  74  as well as through a handle spacer  146 . When the handle  74  is pushed to pivot the handle  74  counterclockwise (all “clockwise” and “counterclockwise” orientations discussed herein will be taken from below the head assembly  22 , as shown in  FIGS. 7-10 ), the link  130  pulls the pawl  76  clockwise. 
         [0033]    A handle tension spring  148  biases the handle  74  to the closed position. To move the handle  74  from the closed, locked position, the operator must overcome the force of the handle tension spring  148  as well as the friction force between the driven jaw  72  and the pawl  76 . A rubber handle grip  150  may be included on the tubular portion  134 , making it easier for the operator to push on and move the handle  74  to overcome the tension and friction forces. While the torsion spring  124  tends to bias the handle  74  away from the closed position, the spring constant of the handle tension spring  148  is much higher than the spring constant of the torsion spring  124 , such that the handle tension spring  148  dominates over the torsion spring  124  for the majority of the handle throw. As the handle  74  pivots, the link  130  takes more and more of the stress of the handle tension spring  148  and provides a mechanical advantage such that the handle throw gets easier and easier even though the tension in the spring  148  is increasing. When the handle  74  gets near the fully opened position, however, the link  130  is nearly inline with the pawl pivot axis  122 , such that the link  130  supports essentially all of the force of the handle tension spring  148 . At this point, the torsion spring  124  overcomes the handle tension spring  148  to hold the pawl  76  and the handle  74  fully opened. (Because the link  130  is not fully inline with the pawl pivot axis  122 , and as long as the jaws  70 ,  72  remain fully closed, the operator can still pull the handle  74  back to its original closed position shown in  FIG. 8  if desired). In the preferred embodiment, the torsion spring  124  overcomes the handle tension spring  148  after a handle throw of about 18°, biasing the handle  74  to a fully opened position where the handle  74  is 20° from its fully closed position. During this opening throw, the link  130  has caused the pawl  76  to rotate about 78° from its locked position shown in  FIGS. 7 and 8  to its fully opened, unlocked position shown in  FIG. 9 . 
         [0034]    Once the corner  152  of the pawl  76  clears the corner  154  of the driven jaw  72  during the opening handle throw (i.e., in the preferred embodiment, when the handle  74  is about 15° from its locked position and the pawl  76  is about 60° from its locked position), the jaws  70 ,  72  are free to release open under the force of the jaw tension spring  126 . Generally speaking, the jaw opening force of the jaw tension spring  126  is not enough to move the kingpin  84 , and the kingpin  84  will maintain the jaws  70 ,  72  in a closed position until the towing vehicle is driven away from the kingpin  84 . The jaws  70 ,  72  open as far as the kingpin  84  will let them while the towing vehicle is driven away from the kingpin  84 , until the kingpin  84  is fully cleared. In the preferred embodiment, a minimum of about 40° of jaw rotation (of each jaw  70 ,  72 ) is required before the kingpin  84  can escape from the jaws  70 ,  72 . As the jaws  70 ,  72  approach a fully opened position toward the position of  FIG. 10  (i.e., once the kingpin  84  permits the jaws  70 ,  72  to rotate about 50° from their closed position in the preferred embodiment), the arm  104  of the driven jaw  72  contacts the reset corner  156  of the pawl  76 . The opening force of the jaw tension spring  126  is greater than the force of the torsion spring  124 . The opening of the jaws  70 ,  72  overcomes the force of the torsion spring  124  and moves the pawl  76 . As the jaws  70 ,  72  complete their opening rotation (i.e., in the preferred embodiment, rotating the jaws  70 ,  72  from about 50° to a fully opened position of about 58° from the closed position), the arm  104  of the driven jaw  72  riding on the reset corner  156  of the pawl  76  causes the pawl  76  to rotate counterclockwise (i.e., in the preferred embodiment, rotating the pawl  76  from about 78° to about 60° from its locked position). This rotation of the pawl  76  in turn causes rotation of the handle  74  from about 20° to about 16° from its locked position, with the handle spring  148  now overcoming the torsion spring  124  to bias the handle  74  clockwise back toward its locked position and to bias the pawl  76  counterclockwise. The open stop surface  158  (called out in  FIGS. 7 and 9 ) of the pawl  76  now contacts against the pawl stop surface  128  (called out in  FIG. 9 ) of the driven jaw  72  in the opened position shown in  FIG. 10 . The opened driven jaw  72  (due to the jaw tension spring  126 ) now prevents the pawl  76  and handle  74  from pivoting further under the force of the handle tension spring  148 . 
         [0035]    The hitch  20  will remain in this open position shown in  FIG. 10  until a force on the jaws  70 ,  72  overcomes the jaw tension spring  126  and causes the jaws  70 ,  72  to close, such as when the towing vehicle is again backed into towing position against the kingpin  84 . As the kingpin  84  pushes forward in the skid plate  80 , the kingpin  84  closes the jaws  70 ,  72  around it. Once the jaws  70 ,  72  sufficiently close around the kingpin  84 , the pawl  76  rotates back to the locked position shown in  FIGS. 7 and 8 , with the nose  152  of the pawl  76  past the pawl stop surface  128  of the driven jaw  72 . Interference between the driven jaw  72  and the pawl  76  now prevents any opening of the jaws  70 ,  72  until the handle  74  is once again pushed to move the pawl  76  out of the way. 
         [0036]    The lock plate  90  and a latch pin  160  interact with the handle  74  in the closed position to prevent inadvertent movement of the handle  74  from the closed position of  FIGS. 7 and 8 . The handle  74  and the lock plate  90  both include mating openings  162  for the latch pin  160 . The user must remove the latch pin  160  from these openings  162  in order to open the handle  74 . 
         [0037]    The preferred embodiment of the present invention also includes a rotary position indicator  78 . A portion of the position indicator  78  is viewable through an opening  164  in the full head weldment  68 , and thus can be seen from someone in front of the hitch  20  such as by the driver of the towing vehicle. The preferred position indicator  78  is hexagonal and mounted on an axle  92 . Three adjacent sides of the position indicator  78  are marked, such as with green, red and yellow coloring, with only one of the three sides showing through the opening  164 . 
         [0038]    Linkage mechanisms to both the handle  74  and the driving jaw  70  are used to control rotation of the position indicator  78  between the three indications. The angular linkage portion  132  of the handle  74  extends past the handle pivot point  166  to an attachment point  168  for a handle indicator link  170 . The driving jaw  70  includes an attachment point  172  for a jaw indicator link  174 . The jaw indicator link  174  includes a tension spring  176 . When the handle  74  is in the closed position as shown in  FIGS. 7 and 8 , the handle indicator link  170  pulls the position indicator  78  so a green side of the position indicator  78  is visible through the opening  164 , with the tension spring  176  at least partially extended. The green indication signals to the operator that the fifth wheel hitch  20  is locked and ready for towing. 
         [0039]    As the handle  74  is rotated to the position shown in  FIG. 9 , contraction of the tension spring  176  in the jaw indicator link  174  pulls on the position indicator  78  to rotate the position indicator  78  counterclockwise, until the red side of the position indicator  78  is visible through the opening  164 . The handle indicator link  170  includes a slot  178 , and the handle attachment  168  translates within the slot  178  to the proximal end of the slot  178  without further rotation of the position indicator  78 . The red indication signals to the operator that the fifth wheel hitch  20  is unlocked but closed. The operator can drive away from the kingpin  84  in this position, but should be prepared for the towed load to disengage. If the kingpin  84  is not in the hitch  20 , the red indication signals that the hitch  20  is not ready for kingpin engagement. 
         [0040]    When the jaws  70 ,  72  open to the position shown in  FIG. 10 , the jaw end of the jaw indicator link  174  moves with driving jaw  70 , further pulling the position indicator  78  about another 60° around the axle  92 , so the yellow side of the position indicator  78  is visible through the opening  164 . The handle attachment  168  translates back within the slot  178  to the distal end of the slot  178 , so the fact that the handle  74  moves very little from the unlocked position of  FIG. 9  to the opened position of  FIG. 10  has no effect on rotation of the position indicator  78 . The yellow indication signals to the operator that the fifth wheel hitch  20  is open and ready for hitching. 
         [0041]    When the jaws  70 ,  72  close around the kingpin  84  and the handle  74  moves back to the closed position of  FIGS. 7 and 8 , the handle indicator link  170  pulls the position indicator 120° so the green side of the position indicator  78  is again showing through the opening  164 . A shield  180  (best shown in  FIGS. 5 and 6 ) can be positioned to hold the position indicator  78  in place on the axle  92  and to partially hide the position indicator  78  so only a single side of the position indicator is visible. The position indicator  78  thus signals to the operator very clearly and unambiguously, in a location visible to the driver of the towing vehicle that does not move, what position (locked, unlocked, or open) the hitch  20  is in. 
         [0042]    For the most part, the components of the head assembly  22  can be formed of a strong metal, such as out of ASTM A36 steel, powder coated for aesthetic appearance and corrosion resistance. Various pins, bolts and nuts can be those readily commercially available, such as formed of stainless steel, and the linkages can also be formed of ASTM 304 stainless steel. In the preferred embodiment, the jaw tension spring  126  has a spring rate of 20 lb/in, the handle tension spring  148  has a spring rate of 18 lb/in, and the extension spring  176  of the jaw linkage has a spring rate of 3 lb/in. The position indicator  78  can be formed of nylon 6/6 or similar non-corroding or corrosion-resistant material which will maintain the colors (or other indication) over years of use. 
         [0043]    Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.