Abstract:
A system is described for detachably securing a housing to a ball hitch (e.g. of the type used in trucks for towing). The system includes a tubular housing for fitting over the ball, and attachment means for detachably securing the housing to the ball. A workpiece can then be secured to the housing, as desired. A preferred attachment means is a pair of opposing lock pins which are movable between retracted and extended positions. When the pins are in the extended position, they secure the housing to the ball hitch. The type of workpieces may vary. For example, the workpiece may be a work table, a vise, a fifth-wheel hitch system, a winch, or an arm for a lift bucket.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon, and claims priority from, my Provisional Application No. 61/853,269, filed Apr. 1, 2013. 
     FIELD OF THE INVENTION 
     This invention relates to ball hitch systems of the type used in trucks for pulling or towing gooseneck trailers. More particularly, this invention relates to use of a ball hitch for supporting different types of hitches or a variety of workpieces. 
     BACKGROUND OF THE PRIOR ART 
     Conventional ball hitch systems used in trucks (e.g. pickup trucks) include a ball which is secured to the frame of the truck in the bed area. A trailer can be connected to the ball for towing purposes. Normally the trailer includes a vertical stem or shank with an opening in its lower end to receive the ball. The vertical stem further includes a locking mechanism to secure the stem to the ball for towing. 
     Sometimes it would be of great benefit if the existing ball hitch system could be used for supporting various types of workpieces, such as a vise, or a work table, or lift bucket, for example. 
     U.S. Pat. No. 7,740,266 (Marcy) describes a system for attenuating intermittent forces at the interconnection between a towing vehicle and a trailer. In one embodiment the system includes an air spring or cushion which acts as a shock absorber between the trailer and the towing vehicle. The system can be connected to a ball hitch which may also include a fifth-wheel hitch for a camper trailer, for example. 
     There has not heretofore been provided a ball hitch conversion system having the advantages and features of the present invention. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention there is provided a system for converting a ball hitch to a support for a variety of workpieces. The workpieces may be, for example, a work table, a winch, a vise, an arm for a lift bucket (e.g. a cherry picker), a fifth-wheel hitch system, etc. In one embodiment, the support system preferably comprises: 
     (a) a tubular housing; 
     (b) attachment means for detachably securing the housing to a ball hitch in a truck bed; wherein the attachment means comprises at least one lock pin carried by the housing which is movable between retracted and extended positions; wherein when the pin is in the extended position it secures the housing to the ball hitch. A workpiece can then be secured to the tubular housing in a number of manners. 
     Other advantages and features of the system of this invention will be apparent from the following detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is described in more detail hereinafter with reference to the accompanying drawings wherein: 
         FIG. 1  is an elevational view (partially cut-away) of one embodiment of a ball hitch conversion system of the invention. 
         FIG. 2  is a side elevational view (partially cut-away) of one embodiment of ball hitch conversion system of the invention. 
         FIG. 3  is a side elevational view of another embodiment of ball hitch conversion system of the invention. 
         FIG. 4  is a top view of the ball hitch conversion embodiment of  FIG. 3 . 
         FIG. 5  is an exploded view of one embodiment of the invention in conjunction with an air cushion. 
         FIGS. 6 ,  7 ,  8 ,  9 ,  10  and  11  illustrate other uses of the ball hitch conversion system of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a front elevational view, partially cut-away, of one embodiment of a ball hitch conversion system  10  of the invention. This embodiment includes housing  12  (preferably ¼ inch wall 4×4 tube) which will fit over the ball  80  of a conventional ball hitch (which is secured to a truck bed). In  FIG. 1  there are shown two locking pins  13  and  14  which are adapted to move in separate guideways  13 A and  14 A between retracted and extended positions to lock the housing onto the ball. The locking pins preferably each comprise a cylinder which has internal threads in each end. A bolt  15  is threaded into each such end of each cylinder. The depth of the thread is matched to the length of the bolt so that when the bolts are tightened they do not clamp against the outside of the housing. Thus, each bolt and cylinder assembly is retained in the housing but can move freely in the guide slots  13 A and  14 A. 
     The means for moving the locking pins from their retracted position to their extended position may vary.  FIG. 1  shows two different ways for moving the locking pins. On the left side of  FIG. 1  there is shown a set screw  16  which is threadably secured in a bracket  18  welded onto the outside of the wall of the housing  12 . The leading end of this screw contacts the side of lock pin  13  and causes it to move upwardly toward the neck portion of the ball. The dotted lines show the extended position of the lock pin  13  where it makes contact with the ball. On the opposite side of the ball there is shown locking pin  14  which also moves in a guideway to contact the neck portion of the ball. This pin  14  is caused to move by means of a cam member  20  which pivots about an axle or pin  21  when associated set screw  17  is turned. Brackets  19 A and  19 B support the cam and associated set screw  17 . Bracket  19 B is welded to housing  12  and also to bracket  19 A and supports axle or pin  21  about which the cam can pivot. 
     Thus,  FIG. 1  shows alternative means for moving the locking pins  13  and  14  from their retracted position to their extended positions in the housing to lock the housing to the ball.  FIG. 1  also shows one type of centering or guide ring  22  welded within the housing to help center the ball within the housing. The guide ring should be positioned near the large diameter of the ball and can be a plate or a ring. 
       FIG. 2  is a side elevational view (partially cut-away) of the ball hitch conversion system of  FIG. 1 . This shows locking pin  14  positioned against the neck portion of the ball  80 . It also shows the manner in which the centering ring  22  maintains the ball  80  in the center of the housing  12 . 
       FIG. 3  is a side elevational view of a ball hitch conversion system in which the means for moving the locking pins involves the use of two set screws  24  and  25  which contact the pins directly to cause the pins to move upwardly in the guideways on opposite sides of the ball. The set screws are threaded through brackets  26 .  FIG. 4  is a top view of the ball hitch conversion of  FIG. 3 . 
     Thus, the ball hitch conversion system comprises a housing which can be positioned over a conventional hitch ball and is centered around a vertical axis of the ball. Preferably two cylindrical wedges or locking pins are included shown which have a diameter such that they can be wedged between the inside walls of the housing and the underside of the hitch ball. The system also includes means for retaining the wedges and moving them between retracted and extended positions. When the pins or wedges are forced upwardly to their extended position, the force pushes upwardly against the ball and equally forces the housing downwardly against the base of the ball, thereby locking the housing rigidly to the ball base support. Thus, anything that is fastened to the housing is also rigidly locked to the ball and its base support. 
       FIG. 5  is an exploded view illustrating another embodiment of a conversion hitch system of the invention. The ball capture system  10  of the invention is secured to the lower end of an elongated shank  70  which is intended to slide into the lower end of gooseneck receiver  90  on a gooseneck trailer. Set screws  92  are tightened to hold shank  70  in place. 
       FIG. 5  also shows an air cushion  60  which includes a ball  62  secured on its upper side which can be captured in the system  10  in accordance with this invention. The air cushion system  60  includes an inflatable air cushion  64  held between upper and lower plates  65  and  66 . One end of plate  66  is hinged on bar  67  to enable plate  66  to move up and down to absorb shocks during towing. The underside of cushion system  60  includes a coupler  68  enabling it to fit over, and couple to, existing ball  100  on truck bed  101 . Using the system of the invention, the air cushion can be adapted to a variety of different towing connections without modifying the cushion. This avoids the need to maintain a large inventory of special cushions. Thus, the system shown in  FIG. 5  enables the cushion to stay with the trailer as opposed to staying with the truck or removing it for storage elsewhere. 
       FIGS. 6-11  illustrate other uses of the ball hitch conversion system of the invention. In  FIG. 6  there is shown a winch  110  on a shank  111  which is slidably received in and pinned to mounting post  112 . The winch includes a cable and hook  113  and electrical leads  114 . The lower end of post  112  can include the ball capture system  10  of  FIG. 1 , for example, so that the post can be mounted or coupled onto a conventional ball hitch in the bed of a truck. 
     In  FIG. 7  a work table  116  (e.g. for supporting a welding project) is pinned to the upper end of post  112 . The lower end of post  112  can include the ball capture system of the invention. 
     In  FIG. 8  there is shown a vise  118  pinned to the upper end of post  112 . In  FIG. 9  there is shown a lift bucket (e.g. a cherry picker) mounted on an arm pinned to the upper end of post  112 . A hydraulic cylinder  121  is used to raise and lower the bucket, as needed. 
       FIG. 10  is a front elevational view (partially cut-away) showing another use of the conversion system of the invention, i.e. to convert a conventional ball hitch  100  in a truck bed  101  to a fifth-wheel hitch system. The lower end of the tubular upright support member or post  112  is detachably secured to the ball  100  by means of lock pins  140  which are urged upwardly against the neck portion of the ball by pivoting cam members  142 . A screw  143 , threaded through bracket  144 , is adapted to pivot about point  145  on each side of the ball to urge the associated cam member against a respective locking pin into the neck portion of the ball beneath the enlarged head portion of the ball. 
     The upper end of support member  112  preferably includes a curved support plate  122 . Attached to the top of plate  122  is the yoke  130  of a conventional fifth-wheel hitch system. The fifth-wheel hitch system includes a receiver portion  132  for receiving and capturing a conventional king pin which is secured to the trailer to be towed. Preferably, the yoke member  130  is attached to the central portion of plate  122  by bolt  124 . Surrounding bolt  124  is spring member  123  for biasing the yoke member back to its center position. Because of the gap  126  between the outer portions of the plate  122  and the yoke, the curved plate enables the yoke member to become tilted relative to the support member  112  (for example, when the towing vehicle and the trailer are traveling over uneven ground). This feature avoids damaging twisting of the trailer relative to the towing vehicle. 
       FIG. 11  illustrates one type of bracing which may be used in conjunction with use of the hitch system of  FIG. 10  in a truck bed  101 . In this situation, brace members  152  (located forwardly and rearwardly of the support post  112  in the truck bed) are attached at their lower ends (by means of bolts  153 ) to the legs of an elongated support base  160  lying on the floor of the truck bed  101 , as shown. Leg extension members  150  can be bolted to the base  160  with bolts  163 . The base  160  includes a centrally located opening  161  which fits around the ball  100  in the bed  101 . The bolts  153  extend through the lower end of each brace  152  and through elongated slots  162  in base member  160 . The upper ends  152 A of the braces  152  lean against opposite sides of the support post  112  beneath stop members  115  (which may be, for example, metal bars welded or otherwise secured to the support post  112  on the forward and rearward surfaces, as shown). Turnbuckles  154  are attached at opposite ends thereof to the two braces  152 . When the turnbuckles are tightened, the upper ends of braces  152  are drawn upwardly against the stop members  115 , and the lower ends of braces  152  are pulled toward the support post (sliding the bolts in the slots  162 ) to complete triangular bracing of the support post. In this manner, the support post  112  is very rigidly held in a straight upright position during use. 
     The use of the ball hitch conversion system in conjunction with a fifth-wheel hitch is also described in my copending application Ser. No. 13/999,677, filed of even date. Other variants are possible without departing from the scope of this invention.