Patent Publication Number: US-2006012145-A1

Title: Wheel assembly for a trailer

Description:
This invention relates to a wheel assemblies for use in pull behind trailers and various other types of trailers and vehicles.  
     BACKGROUND OF THE INVENTION  
      Pull behind trailers have been adapted for a variety of uses and application. The basic pull behind trailer design employs a trailer frame built atop a solid axle wheel assembly. While simple and sturdy, the cross axle wheel assembly used in conventional trailers has several disadvantages.  
      Building the trailer frames atop the wheel assembly raises the center of gravity of the trailer. The higher the center of gravity, the more prone to road sway and yaw the trailer becomes. Excessive sway and yaw can cause a trailer to overturn even at low speeds on straight and level roads. Lowering the center of gravity makes the trailer ride smoother and more safely. While lowering the center of gravity is desirable, ground clearance is also a concern for pull behind trailers. Cross axles and trailer frames can be damaged from road debris. With solid cross axle wheel assemblies, ground clearance can only be improved by increasing the size of the trailer wheels. Furthermore, it is desirable in many applications to lower the trailer floor to facilitate loading of the trailer. Since the trailer frame is built atop a solid cross axle wheel assembly, the trailer floor can not be lowered without compromising ground clearance. Consequently, it is desirable to develop a pull behind trailer and wheel assembly that eliminates the cross axles for improved center of gravity, ground clearance and floor height.  
     SUMMARY OF THE INVENTION  
      The wheel assembly of this invention eliminates the problems associated with solid cross axles in pull behind trailers. The wheel assembly of this invention includes a sturdy fender and a wheel mount pivotally connected to the fender within the wheel well. The wheel mount is suspended by a leaf spring also mounted to the fender within the wheel well. The fender provides the structural support of each wheel assembly and is simply mounted to the trailer frame. The wheel assemblies are mounted directly to the side of the trailer frame, instead of under the trailer frame, which lowers the trailer floor without compromising ground clearance. Since each wheel mount is independently suspended within the wheel well, the trailer rides smoother over rough ground and with less road sway and yaw.  
      Accordingly, an advantage of this invention is that the wheel assembly eliminates the need for a solid cross axle on a pull behind trailer.  
      Another advantage is that each wheel assembly has independent suspension for an improved trailer ride.  
      Another advantage of this invention is that the wheel assembly reduces the center of gravity of the trailer to improve the ride and reduce road sway and yaw.  
      Another advantage is that the wheel assembly improves the ground clearance of the trailer.  
      Another advantage is that the wheel assembly lowers the trailer floor for more convenient loading.  
      Other advantages will become apparent upon a reading of the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      A preferred embodiment of the invention has been depicted for illustrative purposes only wherein:  
       FIG. 1  is a perspective view of the typical pull behind trailer using the wheel assembles of this invention;  
       FIG. 2  is a perspective view of the wheel assembly with the trailer deck outlined in shadow;  
       FIG. 3  is an exploded view of the wheel assembly of this invention;  
       FIG. 4  is a partial sectional side view of the wheel assembly of this invention;  
       FIG. 5  is a partial side sectional view of the wheel assembly of this invention illustrating the pivotal suspension of the wheel mount;  
       FIG. 6  is back sectional view of a conventional trailer using a traditional solid axle wheel assembly;  
       FIG. 7  is a back sectional view of the trailer of  FIG. 1 ;  
       FIG. 8  is side view of a wheel assembly with a tall fender for normal ground clearance;  
       FIG. 9  is a side view of a wheel assembly with a shorter fender for greater ground clearance; and  
       FIG. 10  is a partial side view of a trailer using a wheel assembly of this invention with tandem wheel mounts. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
      The preferred embodiments herein described are not intended to be exhaustive or to limit the invention to the precise form disclosed. They are chosen and described to best explain the invention so that others skilled in the art might utilize its teachings.  
       FIGS. 1-5  illustrate a typical pull behind trailer  2  using the wheel assemblies  10  of this invention. Trailer  2  includes a frame  4  and a floor  6 . As shown in  FIG. 2 , two separate wheel assemblies  10  are mounted to each side of trailer frame  4 . The wheel assembly of this invention is designed for use with all types of light duty pull behind trailers, but may be modified within the scope of this invention for uses with other trailer applications. The trailer depicted in the figures is selected solely for illustrative purposes and is not intended to limit the application of wheel assembly  10  to any particular type or style of trailer.  
      As shown in  FIGS. 3-5 , wheel assembly  10  includes a fender  20 , pivoting wheel mount  30  and a leaf spring  50 . Wheel mount  30  and leaf spring  50  are built into the wheel well  21  of fender  20 , which provides the support structure for the wheel assembly. Fender  20  is stamped or formed of a sturdy sheet metal to have a top  22 , leading wall  24 , a trailing wall  25 , a back wall  26  and a side flaring  28 . The fender  20  is shaped to form a wheel well  21 . Fender  20  also includes mounting flanges  29  that allow the fender to be bolted to the sides of trailer frame  4 .  
      Wheel mount  30  includes a rear swing arm  32 , a bearing hub  40 , an axle shaft  40  and a removable brace plate  44 . As shown, swing arm  32  is pivotally connected to fender  20  between back wall  26  and side flaring  28  adjacent leading wall  24 . Bolts  33  are turned into a bushing  35  that is journalled within a collar  34  extending from the swing arm. Swing arm  32  also has a stop bar  36 , which terminates in a protruding threaded end  37 . A bearing hub  40  turns on an axle shaft  42 , which extends from swing arm  32 . The trailer wheel  12  is mounted to bearing hub  40  and secured by nuts  13  turned onto the lugs  41  of bearing hub  40 . One end of brace plate  44  is bolted to swing arm  32  by a bolt  45 , which is turned in to a threaded bore in swing arm  32  and a nut  47 , which is turned onto threaded stop end  37 . The other end of brace plate  44  is secured to the axle shaft  42  by nut  49 . Removable brace plates  44  provide structural rigidity to wheel mount  30 , and allow wheels  12  to be readily removed for tire repair.  
      Leaf spring  50  insulates wheel mount  30  from shocks transmitted through wheel  12 . While wheel assembles  10  is illustrated using a conventional leaf spring, other suspension mechanisms may be incorporated into the design of the wheel assembly, such as, but not limited to air shocks, elastomers, and coil springs. Leaf spring  50  is seated inside a channel  52  and secured to fender  20  by bolts  53 . Leaf spring  50  is positioned within wheel well  21  so that stop bar  36  of swing arm  32  rests against the leaf spring to provide a suspension ride for trailer  10 . Channel  52  has two end plates  54 , which protect the fender body from wear as leaf spring  50  flexes with the movement of wheel mount  30 . Channel  52  reenforces fender top  22  and skid plates  54  prevent wearing on the fender body.  
       FIGS. 6-10  illustrate several advantages of wheel assembly  10  of this invention over traditional solid axle assemblies used on pull behind trailers.  FIG. 6  shows a conventional solid cross ale wheel assembly of a pull behind trailer where the trailer floor is supported above the cross axle. As such, the height of the trailer floor is above the axle. The height of the axle also dictates the ground clearance of the trailer.  FIG. 7  shows a pull behind trailer using the wheel assembly  10  of this invention. With no solid cross axle, the height of the trailer floor is limited only by the desired ground clearance.  
      As shown in  FIGS. 8 and 9 , wheel assembly  10  can be modified to vary the ground clearance of the trailer by changing the height of the fender or the location where the fenders are mounted to the trailer frames. Shorter fenders provide greater ground clearance, while taller fenders lower the trailer deck for more convenient loading. Mounting the fenders higher on the trailer frames lower the height of the trailer floors and reduce ground clearance. Mounting the fenders lower on the trailer frames raises the floor height and increases the ground clearance. Since the wheel assembly is mounted to the side of the trailer frame, instead of under the frame, the trailer has a lower center of gravity. In addition, each wheel assembly has its own suspension mechanism via the leaf spring, which provide independent suspension from the other wheel assembly. The independent suspension and the lower center of gravity provided by the wheel assembly of this invention improves the ride of the trailer and reduces road sway and yaw.  
       FIG. 10  illustrates a wheel assembly with tandem independent wheel mounts for use with heavy load pull behind trailers, Each of the pivotal wheel mount in the wheel assembly has its own leaf spring suspension built into the fender. The tandem wheel mounts provide more load bearing capacity, while not affecting the independent suspension of the wheel assemblies.  
      It is understood that the above description does not limit the invention to the details given, but may be modified within the scope of the following claims.