Abstract:
A trailer hitch assembly includes a hitch plate and a locking mechanism. The hitch plate includes a throat for receiving a kingpin of a trailer. The locking mechanism locks the kingpin in the throat and includes a pair of lock jaws whose lock jaw contact surface, which contacts the kingpin, is treated with an alloy obviating the need for a lubricant while maintaining the wear life of the pair of lock jaws.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention is generally directed to a fifth wheel hitch and, more specifically, to a fifth wheel hitch that requires reduced or no lubricant.  
         [0002]     Fifth wheel hitches, which are utilized throughout the trucking industry, include a number of moving components, which have required lubricants (e.g., grease) to prevent excessive wear. In general, service technicians have liberally applied lubricants to various components of the fifth wheel hitch to prevent excessive wear. However, applying grease to the fifth wheel requires periodic service and over greasing the fifth wheel can potentially result in harm to the environment (e.g., fire hazard, contamination of storm and/or ground water) as any excess grease may be dispersed into the environment, during operation of an associated tractor trailer unit. In an attempt to reduce lubricant utilization, a number of manufacturers have implemented greaseless fifth wheel top plate pads, as well as grease free plastic and specialty metal front lock and bearing pocket inserts. A number of coupler manufacturers have also utilized protective layers that are painted or electroplated to fifth wheel components to inhibit corrosion. However, in general, these protective layers have not enhanced wear of the components or provided lubricity.  
         [0003]     Further, in general, metal objects that are exposed to various environmental conditions suffer from oxidation, corrosion and rusting. Typically, surfaces of metal objects have been protected by painting, cladding, coating or electroplating the metal surfaces with a protective layer. However, these techniques have proven somewhat undesirable as such protective layers have frequently required partial removal and application of another protective layer to the surface of the metal object when the original protective layer has separated from the surface of the metal object. As a result, researchers have developed various other processes that alloys materials to surfaces of metal objects. For example, one process known as laser induced surface improvements (LISI) is directed to alloying a desired metal to a surface of a metal object with a laser. Apparatuses and techniques for implementing the LISI process are described in U.S. Pat. Nos. 5,961,861; 5,985,056; 6,016,227; and 6,229,118; which are all hereby incorporated herein by reference in their entirety.  
         [0004]     What is needed is a fifth wheel hitch whose components exhibit enhanced wear and corrosion resistance, while minimizing the application of applied lubricants.  
       SUMMARY OF THE INVENTION  
       [0005]     An embodiment of the present invention is directed to a trailer hitch assembly that includes a hitch plate and a locking mechanism. The hitch plate includes a throat for receiving a kingpin of a trailer. The locking mechanism locks the kingpin in the throat and includes a pair of lock jaws whose lock jaw contact surface, which contacts the kingpin, is treated with an alloy obviating the need for a lubricant while maintaining the wear life of the pair of lock jaws.  
         [0006]     According to another embodiment of the present invention, a trailer hitch assembly is provided that includes a hitch plate and a locking mechanism. The hitch plate includes a throat for receiving a kingpin of a trailer and the locking mechanism locks the kingpin in the throat and includes a front lock insert coupled to the hitch plate whose insert contact surface, which contacts the kingpin, is treated with an alloy obviating the need for a lubricant while maintaining the wear life of the insert.  
         [0007]     These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     In the drawings:  
         [0009]      FIG. 1A  is a side view of an exemplary truck tractor including a trailer hitch assembly;  
         [0010]      FIG. 1B  is a bottom view of the trailer hitch assembly of  FIG. 1A ;  
         [0011]      FIG. 1C  is a side view of the trailer hitch assembly of  FIG. 1A ;  
         [0012]      FIG. 1D  is a side view of a partial cross-section of the trailer hitch assembly shown in  FIG. 1B ;  
         [0013]      FIG. 2  is a perspective view of a portion of a hitch plate including lock jaws treated according to an embodiment of the present invention;  
         [0014]      FIG. 3  is a perspective view of a portion of a hitch plate at a front lock area of a trailer hitch assembly including an insert treated according to another embodiment of the present invention; and  
         [0015]      FIG. 4  is a view of a portion of a hitch plate at a front lock area of a trailer hitch assembly including another insert treated according to yet another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0016]     The present invention is directed to a trailer hitch assembly (fifth wheel hitch) that employs the selective application of advanced coatings and surface treatments to specific mechanical components of the trailer hitch assembly to provide enhanced wear, superior corrosion resistance and lubricity, while decreasing the need for applied lubricants (e.g., grease). In various embodiments of the present invention, lock jaws of the trailer hitch assembly and a front lock insert of the trailer hitch assembly are treated using a laser induced surface improvement (LISI) process. It should be appreciated that trailer hitch assemblies utilized in tractor trailers include a plurality of moving components, which have generally required liberal application of lubricants. According to one embodiment of the present invention, the need for lubricants is eliminated in the coupler mechanism through surface treatments of various components associated with the coupler mechanism (i.e., the front lock insert or a front lock area of the hitch plate and the lock jaws).  
         [0017]     According to the present invention, the direction of the rasters (i.e., vertical or horizontal laser lines) and the spacing of the rasters are selected to provide optimum performance. In one application, a metalized slurry is produced and the metalized slurry is placed on a wear surface of the component to be treated. From that point, a laser is utilized to basically micro-weld (i.e., alloy) the slurry to the surface of the component. The slurry may include a variety of materials, such as titanium boride with molybdenum, chrome boride or chromium with boron. In general, it is desirable to raster the material onto the metal surface of the component in a direction that is parallel to the direction of greatest wear. In this manner, when two surfaces move in relationship to each other, they move parallel or with the rasters as opposed to running perpendicular to the rasters. It should also be appreciated that the dimensions of a component may need to be reduced (e.g., 0.004 of an inch may be removed) to accommodate for the alloy and maintain proper tolerances.  
         [0018]     In general, it should be appreciated that wear treatment of all metal surfaces of components associated with tractor trailer unit mechanisms that move with respect to one another may be beneficial. For example, a horn on a pintle hook may be treated or other high wear surfaces, such as bushing contacts and/or a slider edge that runs between a suspension slide frame of a trailer, may benefit from a similar treatment as disclosed herein.  
         [0019]      FIG. 1A  shows an exemplary truck tractor  10 , which includes a trailer hitch assembly  20  having a base  24  securely mounted to a chassis  80 , a trailer hitch plate  26  pivotally mounted on the base  24  on a transverse axis and a locking mechanism  28  for locking a conventional trailer kingpin in place. As shown, the truck tractor  10  includes an electronic system that includes three proximity sensors mounted to the hitch assembly  20  and an output device  50  mounted in the cab of the tractor  10 . It should be understood that the electronic system is not a part of the present invention. The sensors, which may include a tilt sensor  32 , a kingpin sensor  34  and a lock sensor  36 , are coupled to the output device  50  by a multi-conductor cable  45  and are mounted at appropriate locations to the trailer hitch assembly  20 .  
         [0020]      FIGS. 1B-1D  provide more detailed views of the trailer hitch assembly  20  of  FIG. 1A . The tilt sensor  32  may be mounted on a flange  23  of the hitch plate  26  such that a sensing end faces outward in a direction perpendicular to pivot pins  21 .  FIG. 1C  shows the hitch plate  26  from the side in combination with the base  24  in a coupled horizontal position  25  and in an uncoupled at rest position  27  (dashed lines). By mounting a metal plate  85  on the chassis  80  in a position near where the sensing end of the tilt sensor  32  is positioned when the trailer hitch plate  26  is in the resting position, the tilt sensor  32  detects the presence of the plate  85  as a basis for determining that the hitch plate  26  is tilted or at a rest position. When the tractor  10  is backed under a trailer, contact is made between the tilted hitch plate  26  and a portion of the trailer. This contact causes the hitch plate  26  to rotate into a coupled (horizontal) position. When the tilt sensor  32  subsequently detects the absence of the plate  85 , it can be concluded that the hitch plate  26  has been moved from its rest position and the trailer is in proximity to the hitch assembly  20 . Alternatively, the sensor  32  may be mounted so as to detect metal when the hitch plate  26  is in the horizontal coupled position.  
         [0021]      FIG. 1B  shows the kingpin sensor  34  mounted to the hitch plate  26  with a sensing end near the throat  60  formed in the hitch plate  26 , into which a trailer kingpin  70  is positioned and locked.  FIG. 1D  provides an upside-down side view of a partial cross-section illustrating the location of the trailer kingpin  70  when properly disposed in the throat  60 . As constructed, the kingpin sensor  34  outputs a detection signal when the lower flange of the metal trailer kingpin  70  is disposed in the throat  60 , below a lock plane  61 . That is, the kingpin sensor  34  is in a plane below the locking mechanism  28  and only detects the kingpin  70  when a kingpin rib  62  of the kingpin  70  extends below the lock plane  61 . The location of the kingpin sensor  34  prevents it from indicating that the kingpin  70  is present when a high coupling occurs, which prevents the locking mechanism  28  from securing the kingpin  70  (i.e., the trailer) to the hitch assembly  20 . The locking mechanism  28 , of the hitch assembly  20 , is biased by a compression spring to automatically lock-in and secure the trailer kingpin  70 , as soon as it enters the hitch throat  60 .  
         [0022]      FIG. 1B  also depicts the lock sensor  36  mounted to the hitch plate  26  such that a sensing end is in a position proximate to a position of that of a metal cam plate  29  (of the locking mechanism  28 ) when in a locked position. In this manner, the lock sensor  36  detects the presence of the cam plate  29  as a basis for detecting if the locking mechanism  28  is in a locked and secured position. Those of ordinary skill in the art will appreciate that the present invention may be used in connection with any type of locking mechanism. It should also be noted that the present invention may be applied to trailer hitch assemblies having other constructions and is not limited to the particular mounting locations shown for the sensors  32 ,  34  and  36 . Further, the various embodiments of the present invention are equally applicable to trailer hitch assemblies that do not include an electronic system, which is utilized to monitor the status of the assembly.  
         [0023]      FIG. 2  depicts various components typically associated with the trailer hitch assembly  20  of  FIG. 1A . More specifically, a partial view of a hitch plate  26   a  with an attached pair of lock jaws  201   a  and  201   b , which have been alloyed using the LISI process, are depicted. As shown in  FIG. 2 , raster lines of the lock jaws  201   a  and  201   b  run in a horizontal direction. As previously mentioned, depending upon the application, it may be preferable for the direction of the raster lines to be directed parallel to the direction of greatest wear. It should be appreciated that other processes which alloy a wear resistant material (i.e., a metal) that provides lubricity may be utilized and that the LISI process is not the only process that can be utilized to alloy appropriate metals to steel components associated with a trailer hitch assembly. It may also be beneficial to treat other components (e.g., a yoke, a cam plate, lock pins, yoke shaft, etc.) that experience less wear with commercially available baked on coatings, such as a dry film lubricant containing molybdenum disulfide. Components, such as a cam roller, may be through-hardened and cam washers may be made of Nylatron™ or stainless steel.  
         [0024]      FIG. 3  illustrates a portion of a hitch plate  26   b  at a front lock area  303  of a trailer hitch assembly, according to one embodiment of the present invention. As is shown in  FIG. 3 , a front lock insert  301  is shaped to be received in the hitch plate  26   b  in the front lock area  303 . It should be appreciated that a hitch plate may be configured such that an insert is not utilized and, in this case, it is desirable to treat the hitch plate in the front lock area with an alloy that resists wear and provides lubricity.  
         [0025]      FIG. 4  is a view of a portion of a hitch plate  26   c  at a front lock area  403  of a trailer hitch assembly, according to another embodiment of the present invention. As is shown in  FIG. 4 , a front lock insert  401  is shaped to be received by the hitch plate  26   c  in the front lock area  403  and is fixed to the hitch plate  26   c  with a pair of fasteners (e.g., set screws)  405 .  
         [0026]     Accordingly, a trailer hitch assembly has been described herein that employs the selective application of advanced coatings and surface treatments to specific mechanical components of the fifth wheel hitch to provide enhanced wear, corrosion resistance and lubricity, which obviates the need for applied lubricants to components so treated.  
         [0027]     The above description is considered that of the preferred embodiments only. Modification of the invention will occur to those skilled in the art and to those who make or use the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and not intended to limit the scope of the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the Doctrine of Equivalents.