Patent Publication Number: US-6983950-B2

Title: Quick change hitch ball assembly

Description:
This application is a continuation of U.S. application Ser. No. 10/113,443 filed Mar. 29, 2002 entitled “Interchangeable Hitch Ball having Plunger with J-Shaped Channel” now U.S. Pat. No 6,783,144, which claims the benefit of Provisional Application No. 60/281,140, filed Apr. 3, 2001, which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to the towing field and, more particularly, to a spring-loaded interchangeable hitch ball assembly which allows an operator to quickly and conveniently change from one size towing ball to another in order to meet the needs of any particular application. 
     BACKGROUND OF THE INVENTION 
     The use of a ball joint coupling comprising a towing ball and cooperating socket assembly in order to tow a trailer behind a towing vehicle is well known in the art. Such an arrangement provides the necessary freedom of movement to allow a trailer to track smoothly behind the towing vehicle while also providing a dependable connection. 
     Over the years, towing balls of various diameters have been used for this purpose and several industry standard sizes (e.g. 1⅞ inch, 2 inch, 2¼ inch and 2 5/16 inch in diameter) are now in frequent use. As a result, it is not uncommon for a single towing vehicle to be used to tow various trailers where those trailers are equipped with socket assemblies adapted for operative connection with towing balls of different diameters. Thus, a need is identified for a hitch ball assembly allowing easy and convenient interchange of towing balls of different diameters so that the hitch of the towing vehicle may be tailored to fit the socket assembly of the trailer to be towed and thereby meet application needs. 
     Toward this end, a number of approaches have been proposed in the past. Representative of the interchangeable hitch ball art are U.S. Pat. No. 4,433,854 to Smith, U.S. Pat. No. 5,419,576 to Van Vleet, U.S. Pat. No. 5,116,072 to Swenson and U.S. Pat. No. 4,522,421 to Vance. 
     The Smith &#39;854 patent discloses a post for a towing ball incorporating a spring-biased latch pin for releasably attaching the towing ball to the base. The Van Vleet &#39;576 patent discloses a post and towing ball secured together by means of a fastening pin. While the approaches disclosed in these patents provide secure connection of the towing ball to the post, the latch pins prevent rotation of the towing ball relative to the post. Such rotation is desirable as it minimizes binding forces and promotes articulation and smooth trailer tracking at both highway speeds and when maneuvering slowly in confined areas. 
     The Swenson &#39;072 patent discloses an interchangeable hitch ball assembly including a post having an annular groove. The towing ball is secured to the post by means of an offset pin which extends tangentially through the annular groove so as to allow relative rotation of the towing ball on the post. There, however, is some difficulty in effectively securing the pin in position and the structure proposed in the Swenson patent for this purpose is relatively expensive to produce. 
     The Vance &#39;421 patent discloses an interchangeable trailer ball assembly incorporating a mounting post including a threaded stem, a base, an axial bore and a pair of laterally extending bores. A tapered plunger is received in the axial bore. The plunger is biased by means of a spring into a position wherein ball bearings are forced outwardly into engagement with an annular groove or race in the towing ball thereby locking the towing ball in position on the post. An actuator rod may be extended into the axial bore to engage and lift the plunger so as to release the ball bearings from the groove or race and allow removal of the towing ball. While effective, significant user inconvenience may result as the user may need to stoop or lay on the ground in order to fish the actuator rod up through the axial bore which opens toward the ground. This can be a particularly disturbing problem if the ground is wet and/or muddy. 
     A need is therefore identified for an improved interchangeable hitch ball assembly. 
     SUMMARY OF THE INVENTION 
     The advantages and novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. The advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
     In accordance with the purpose of the present invention as described herein, an improved hitch ball assembly is provided. The hitch ball assembly may be broadly defined as including a post and a towing ball carried on the post. At least one displaceable locking element is also carried on the post in either (a) a first position free of securing engagement with the towing ball or (b) a second position in securing engagement with the towing ball. Further, the assembly includes a plunger carried on the post. The plunger includes at least one channel for engaging and receiving the at least one displaceable element. 
     Still more specifically defining the invention, the hitch ball assembly may include a towing ball having a mounting aperture and an annular race in communication with the mounting aperture. The assembly also includes a post having a base, an axial bore and at least one opening in communication with the axial bore. In a typical arrangement, two opposed openings are provided. 
     The hitch ball assembly further includes a ball bearing received in each of the openings. Further, a plunger is provided including at least one J-shaped channel. The plunger is carried in the axial bore of the post. Additionally, the hitch ball assembly includes a spring received in the axial bore and engaging an end of the plunger. The spring functions to bias the plunger into a first position. 
     More specifically describing the invention, the plunger includes a J-shaped channel for receiving each ball bearing. Each J-shaped channel includes a cavity at a first end. When the plunger is biased by the spring into the first position, the ball bearings are aligned with and received in the cavities. In this position the ball bearings are received more fully within the post and therefore are free of securing engagement with the towing ball. Thus, the towing ball may be removed from or installed on the post in this position of the plunger. 
     In accordance with additional and more specific aspects of the present invention, the post further includes a threaded mounting stem depending from the base. It is this mounting stem that allows the post to be secured to a hitch bar, tow bar, ball mount head or the like. Additionally, the post is tapered to aid in the securing and removing of the hitch ball on the post. 
     Still further, the towing ball includes a circular opening in communication with the mounting aperture and the plunger includes a slotted head. With the hitch ball mounted on the post, the slotted head extends through the circular opening so as to be engageable by a tool which may be manipulated to rotate and thereby displace the plunger between the first position, allowing installation or removal of the towing ball, and a second position wherein the plunger forces the ball bearings to project further from the post and engage the annular race in the towing ball. This functions to secure the towing ball to the post while allowing the towing ball to rotate freely on the post. It should also be appreciated that the edges of the post defining the openings around the ball bearings are staked so as to prevent the ball bearings from falling out of the post when the towing ball is removed. 
     Still other features of the present invention will become apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of this invention, simply by way of illustration of one of the modes best suited to carry out the invention. As it will be realized, the invention is capable of other different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the present invention and together with the description serve to explain the principles of the invention. In the drawings: 
         FIG. 1  is a partially exploded, perspective view of the present invention; 
         FIG. 2  is a detailed cross sectional partially exploded view showing the present invention in the first operative position with the towing ball removed from the post and the ball bearings received in the cavities of the plunger; 
         FIG. 3  is a detailed cross sectional view showing the present invention in the second operative position with the towing ball securely held on the post by engagement of the ball bearings held in the post projecting into the annular race in the towing ball; and 
         FIG. 4  is a detailed perspective view of the plunger, clearly illustrating one of the J-shaped channels. 
     
    
    
     Reference will now be made in detail to the present preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference is now made to  FIGS. 1–4  showing the hitch ball assembly  10  of the present invention. The assembly  10  includes a post generally designated by reference numeral  12  and a towing ball  14 . As shown, the post  12  includes a base  16 . A threaded stem  18  depends from the base. The post  12  is mounted to a hitch bar or draw bar by extending the threaded stem  18  through an aperture in the hitch bar so that the base  16  rests flat on the hitch bar. A cooperating nut  20  and lock washer  22  are then engaged over the threaded stem  18 . The nut  20  is tightened to provide a secure connection. Of course, a locknut could be utilized in place of the cooperating nut  20  and lock washer  22 . 
     As best shown in  FIGS. 2 and 3 , the post  12  includes a tapered upper portion  24  which has an axial bore  26 . A plurality of openings  28  extend through the wall of the tapered upper portion  24  and communicate with the axial bore  26 . While two opposed openings  28  are illustrated in  FIGS. 2 and 3 , it should be appreciated that less or more could be provided in the same plane radially around the circumference of the tapered upper portion  24 . A displaceable locking element such as a ball bearing  30  is provided in each of the openings  28 . Preferably, the edges  32  of the outer wall of the tapered upper portion  24  defining the openings  28  are staked so as to retain the ball bearings  30  in the openings. 
     The towing ball  14  includes (a) a mounting aperture  34  tapered to match the upper post portion  24 ; (b) a circular opening  35  extending through the top of the ball in communication with the mounting aperture; and (c) an internal, annular race  36  extending continuously around and in communication with the mounting aperture  34 . The annular race  36  is sized and shaped to receive the ball bearings in the manner shown in  FIG. 3 . 
     A plunger  38  is held in the axial bore  26 . As best shown in  FIG. 4 , the plunger  38  includes one or more J-shaped channels  40  with one J-shaped channel being provided for each one of the ball bearings  30 . As shown, each J-shaped channel  40  includes a ball bearing receiving cavity  42  at a first end thereof. The plunger  38  also includes a slotted head  48 . As illustrated, the ball bearing receiving cavity  42  is at the end of the plunger  38  opposite the slotted head  48 . 
     As best illustrated in  FIGS. 2 and 3 , a compression spring  50  is positioned in the axial bore  26  of the post  12 . One end of the compression spring  50  engages the bottom wall  51  of the axial bore  26  while the other end engages the bottom wall  47  of the plunger  38 . As a consequence, the compression spring  50  functions to bias the plunger  38  into a first position shown in  FIG. 2 . In that first position, the ball bearing receiving cavities  42  at the ends of the J-shaped channels  40  in the plunger  38  are aligned with and receive the ball bearings  30 . The ball bearing receiving cavities  42  are of sufficient depth to receive the greater portion of the ball bearings  30 . As a consequence, the ball bearings  30  have sufficient clearance to retract fully within the outer sidewall margin of the tapered upper portion  24  of the post  12 . In this retracted position the ball bearings  30  do not interfere with the installation or removal of a towing ball  14  on the post  12 . Of course, the tapering of the upper post portion  24  aids in the free removal and seating of the towing ball  14  on the post  12  when changing towing balls. 
     When the towing ball  14  is fully seated on the post  12  as shown in  FIG. 3 , the plunger  38  extends through the opening  35  and an annular shoulder  44  at the end of the mounting aperture  34  engages the upper edge  46  of the post  12 . In the seated position, the annular race  36  in the towing ball  14  is aligned in the same plane with the openings  28  and ball bearings  30 . In this position, the plunger  38  may be manipulated to secure the towing ball  14  in position. More specifically, a screwdriver or other tool may be used to engage the slotted head  48  of the plunger  38 . The plunger  38  is then depressed downwardly into the axial bore  26  of the post  12  against the biasing force of the compression spring  50 . As the plunger  38  is depressed, the ball bearings  30  are forced from the ball bearing receiving cavities  42  into the first leg  52  of each J-shaped channel  40  in the plunger  38 . Each of the first legs  52  is of shallower depth than the ball bearing receiving cavities  42  and, accordingly, the plunger  38  effectively forces the ball bearings  30  to project outwardly through the openings  28  beyond the sidewall of the tapered upper post portion  24 . As a result, a portion of the ball bearings  30  are received in the annular race  36  which extends continuously around the inner wall of the towing ball  14 . 
     Once the plunger  38  has been depressed sufficiently to bring the ball bearings into the bend  54  of each of the J-shaped channels  40 , the plunger is rotated slightly in a clockwise direction. In this manner the ball bearings  30  move through the bend  54  into the second leg  56  of the J-shaped channels  40 . The plunger  38  is then released and the compression spring  50  biases the plunger so that the ball bearings  30  each rest at the bottom  57  of the second leg  56  as best shown in detail in  FIG. 3 . The intermediate wall  60  between the first and second legs  52 , 56  around which the bend  54  is formed functions to hold the ball bearings  30  in the second leg  56  and prevents their free movement into the first leg  52  leading to the ball bearing receiving cavities  42 . Thus, in this second position shown in  FIG. 3 , it should be appreciated that the towing ball  14  is securely held on the post  12  by the engagement of the projecting ball bearings  30  in the annular race  36  of the towing ball. 
     Simultaneously, the ball bearings  30  are able to move freely through the annular race  36  and as a result, this structure allows relative rotation of the towing ball  14  on the post  12 . This rotation helps ensure binding free towing and smooth trailer tracking under substantially any foreseeable operating conditions. This relative rotation prevents the ball  14  from freezing in place and reduces the wear on the ball and the trailer socket assembly. 
     If the operator needs to change the towing ball  14  for any reason, this maybe conveniently and easily accomplished in a quick and efficient manner. First, the plunger  38  is depressed slightly so that the ball bearings  30  are brought into the upper portion of the second leg  56  of the J-shaped channel  40  which communicates with the bend  54 . The plunger  38  is then rotated slightly counterclockwise by engagement of an appropriate tool in the slotted head  48 . This causes the ball bearings  30  to move through the bend  54  over the intermediate wall  60 , bringing them into alignment with the upper portion of the first leg  52  of the J-shaped channel  40 . It should be appreciated that the V-shape of the wall  61  of the channel  40  opposite the wall  60  prevents the ball from hanging up in any way along the top of the wall  60 . The plunger  38  is then released and the compression spring  50  biases the plunger upwardly giving a clear visual indication of the unlocked condition of the plunger. 
     As the plunger  38  rises upwardly from the post  12  out of the axial bore  26 , the ball bearings  30  pass along the first leg  52  and are then received in the ball bearing receiving cavities  42 . As noted above, these ball bearing receiving cavities  42  are of sufficient depth to receive the greater portion of the ball bearings  30 . In this position, as the towing ball  14  is lifted from the post  12 , the ball bearings  30  retract within the openings  28  in the upper post portion  24  until the ball bearings are free of the annular race  36 . The towing ball  14  may then be easily removed from the post  12 . The operator then selects a new towing ball  14  for installation on the post  12  and that installation is completed in the manner already described. 
     The foregoing description of a preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiment was chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.