Patent Publication Number: US-2007102898-A1

Title: Pintle hook and ball hitch assemby shock absorber

Description:
FIELD OF THE INVENTION  
      The invention relates to the shock absorbing of a pintle hook and hitch ball assembly used to tow trailers, typically having a gross trailer weight (GWT) of about 10,000 pounds and higher.  
     BACKGROUND OF THE INVENTION  
      Current pintle hook assemblies allow for relatively extreme jarring and shock to drivers and passengers in tow vehicles, especially when the brakes are applied or when the vehicle is placed in motion. Typically, the tow ring gap around the ball is the problem. When a tow vehicle has to brake suddenly, the tow ring connected to the trailer slides forward and slams against one side of the ball of the ball and pintle hook assembly. When the tow vehicle accelerates, the tow ring then slides away from the ball and pintle hook assembly and slams against the opposite side of the ball. The result is a whip lash effect to the individuals inside the tow vehicle cab.  
      The purpose of the present invention is to provide a shock absorbing device and method to prevent or substantially reduce the whip lashing caused by the sliding of the tow ring back and forth against the ball whenever braking or accelerating occurs.  
     SUMMARY OF THE INVENTION  
      As a general application, the present invention is anticipated to be applied to trailing devices using tow rings and pintle hooks. These systems are usually found where the trailer GTW may be 10,000 pounds and higher.  
      The present invention involves the use of a shock absorber bushing around the ball and between the ball and tow ring. The shock absorber bushing can be cylindrically-shaped and adapted to have an interior hollow dimension to easily slide over the ball. Its length is configured to extend at least to a height above the centerline of the ball and preferably so its top surface is aligned relatively close to the height of the ball. In a preferred embodiment, the shock absorber bushing has a flanged portion at its bottom side that is dimensioned in thickness and width to provide some vertical movement shock absorbing effect due to the action of the tow ring bouncing up and down when hitting bumps in the road surface.  
      The shock absorbing system can be made from materials suitable to withstand the significant lateral compressive forces exerted by the tow ring on the ball within the pintle hook or the downward vertical forces on the pintle hook lower half, without permanently deforming and cracking the bushing. For example, one type of suitable material is a vulcanized rubber and/or plastic based material. The material used to make hockey pucks provides for a vulcanized rubber material that can withstand significant impact compressive forces. Material having similar characteristics would be suitable for use as a shock absorber. That is, the bushing effectively has to have characteristics where its elastic deformation, its pliancy, and its overall elasticity, strength and stability are suitable for be subjected to such harsh forces. In addition, fiber reinforced or meshed composites made of plastic or polymer based materials, rubber materials and combinations thereof similar to the materials used in the automotive industry and aircraft industry are other examples of anticipated suitable materials. The material must also have bearing characteristics that would allow for the easy rotation of the ball within the interior of the shock absorber when the tow vehicle is turning. Given these characteristics, one skilled in the art can produce a variety of composite materials from polymer/plastic material, vulcanized rubber materials or combinations thereof to form the shock absorber bushing with well known materials. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      In the accompanying drawings:  
       FIG. 1  is a perspective conceptual view of a pintle hook trailering assembly with one embodiment of the present invention installed;  
       FIG. 2  is a perspective partial cross-section view depicting the embodiment being used in  FIG. 1 ; and  
       FIG. 3A  is a perspective view of the present invention bushing used in  FIG. 1 ; and  
       FIG. 3B  is a perspective view of an alternative embodiment of the present invention bushing.  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Referring now to the drawings,  FIGS. 1-2  and  3 A- 3 B disclose the present invention, which is a pintle hook and ball assembly shock absorber and is depicted generally as  10 .  
      In  FIGS. 1-2 , the pintle hook  20   a  is shown connected to pintle hook mounting plate  20   b , which is connected to the tow vehicle (not shown). The trailer ball hitch or ball  20   d  is attached to the bottom portion of the pintle hook  20   a . When attaching a trailer for towing, the upper half of the pintle hook  20   a  has a portion that pivots away to all for the tow ring  20   c  to be installed over and around the ball  20   d , then the upper half is re-positioned to lock the tow ring  20   c  in place for towing.  
      As can be viewed in the drawing, the present invention  10  (bushing  12   a  or bushing  12   b ) is first placed around the ball. If the bushing has a flanged portion  12   a ′ such as that depicted in  FIGS. 1-2  and  3 A, the flanged portion  12   a ′ is preferably placed against the bottom half of the pintle hook  20   a.    
      The overall diameter of the cylindrical portion of the bushing  12   a , 12   b  should be sized so as to minimize the back and forth movement of the tow ring  20   c , yet have sufficient tolerance to allow for easy turning of the ball  20   d  relative to the inside of the bushing  12   a , 12   b  when turns are being made by the tow vehicle.  
      It should be understood that the preceding is merely a detailed description of one or more embodiments of this invention and that numerous changes to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the spirit and scope of the invention. The preceding description, therefore, is not meant to limit the scope of the invention. Rather, the scope of the invention is to be determined only by the appended claims and their equivalents.