Abstract:
An automatic locking trailer hitch comprising a housing having a first portion adapted to be connected to the tongue of a draft vehicle and a second portion forming a socket for receipt of a ball member, a trigger assembly responsive to a ball entering a socket to move a keeper assembly and a locking assembly to maintain said keeper assembly in a locked position relative to the ball.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the priority of U.S. Provisional Application No. 60/994,287 filed on Sep. 19, 2007, the disclosure of which is incorporated herein by reference for all purposes. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a trailer hitch and, more specifically, to an automatic locking trailer hitch. 
         [0004]    2. Description of the Prior Art 
         [0005]    The prior art abounds with numerous types of trailer coupling for detachably connecting a trailer or the like to a draft vehicle such as an automobile. Most commonly used trailer couplings comprise a ball member attached to the rear structure of the draft vehicle and a socket forming structure attached to the tongue of a pulled vehicle e.g. a trailer. In order to permit the trailer to be readily detached from the drive vehicle, it is common practice to provide a latch on the socket forming structure which is manually movable to engage the ball member and to latch the ball member in place in the socket but is likewise releasable whenever disconnection of the trailer from the draft vehicle is desired. 
         [0006]    While the prior art ball and socket couplings are satisfactory in actual use when the ball locking latch has been properly manipulated, it frequently happens that the users forget to activate the latch into a final locking position. When this occurs, the latch may merely loosely connect the ball member and the socket. While this will usually prevent separation of the ball from the socket while the trailer is advancing over a relatively smooth pavement, when travelling over rough terrain or with sufficient relative vertical movement between the trailer and the draft vehicle, the looseness can result in the ball leaving the socket with the result that the draft vehicle and the trailer are disconnected, often with disastrous results. 
         [0007]    Numerous automatic locking trailer hitches have been proposed as, for example, in U.S. Pat. No. 2,855,222. 
       SUMMARY OF THE INVENTION 
       [0008]    In one aspect the present invention provides an automatic trailer hitch comprising a housing having a portion attachable to the tongue or other structure of a draft vehicle, the housing forming a socket for receipt of the ball member mounted on the tongue of a trailer to be pulled; a keeper for maintaining the ball in the socket, i.e., in an engaged position; a trigger for setting the keeper in the engaged position and; a selectively releasable lock for holding the keeper in the engaged position. 
         [0009]    The foregoing objects, features and advantages of the present invention, as well as others, will be more fully understood and better appreciated by reference to the following drawings, specification and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a side, elevational view, partly in sections, showing one embodiment of the locking trailer hitch of the present invention. 
           [0011]      FIG. 2  is a view taken along the lines  2 - 2  of  FIG. 1 . 
           [0012]      FIG. 3  is a view taken along the lines  3 - 3  of  FIG. 1 . 
           [0013]      FIG. 4  is a bottom plan view of the trailer hitch shown in  FIG. 1 . 
           [0014]      FIG. 5  is a view similar to  FIG. 1  showing the trailer hitch of the present invention in the open position. 
           [0015]      FIG. 6  is a partial, top view of the trailer hitch of the present invention. 
           [0016]      FIG. 7  is a partial, side view, partly in section, showing an alternative embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0017]    Reference is made to  FIG. 1  which shows the automatic trailer hitch of the present invention in the locked or engaged position, the trailer hitch, shown generally as  10 , comprises a housing  12  having a first portion  12 A forming an elongate channel for engaging the tongue  40  of a draft vehicle, housing portion  12 A being connected to tongue  40  by means of a bolt  42  extending through registering holes in tongue  40  and housing portion  12 A. Housing  12  also includes a socket forming portion  12 B forming a socket  14  for receipt of a ball  32  attached in the well known manner to the tongue  13  of a trailer. Housing portion  12 A has a slot  11 B in the top surface, the bottom of housing  12  being open. Extending through slot  11  B out of housing  12  is the lever  44  of a lock assembly shown generally as  20 . Lever  44  is secured to a sleeve  44 A which is rotatable around a pivot pin  26  thereby pivotally mounting lever  44  in housing  12 . Locking mechanism  20  further includes a stop  38  by a bar like structure which also is secured to sleeve  44 A. Thus, stop  38 , like lever  44 , are pivotally mounted around pivot pin  26  for simultaneous movement. 
         [0018]    A keeper mechanism shown generally as  18  comprises an arm  48  which is secured at its lower end to a frame  28  having a pair of spaced apart legs  34 , legs  34  forming a pair of stop shoulders  36 . Frame  28  further has a concave ball engaging surface  30 . Arm  48  is pivotally mounted in housing  12  by means of a pivot pin  24  and extends through a slot  25  in housing portion  12 A. A compression spring  22  has one end connected to lever  44  and the other end to arm  48  of keeper mechanism  18 . 
         [0019]    A triggering device shown generally as  16  comprises a piston housing  66  which is secured to housing portion  12 B, housing  66  defining a chamber in open communication with socket  14 . Disposed in piston housing  66  is a piston  56  which is connected to a piston rod  57 , a compression spring  60  being in surrounding relation to piston rod  57 , spring  60  being trapped between piston  56  and the upper wall of housing  66 . Piston rod  57  extends through an opening  59  in the upper wall of piston housing  66  and is connected to a piston head  58 . 
         [0020]    A slide plate  50  is pivotally connected as at  52  to arm  48  and has a keyhole opening  54  comprised, as shown in  FIG. 6 , of an enlarged area portion  54 A and a reduced area portion  54 B. As best seen by comparison of  FIGS. 1 and 5 , slide plate  50  is movable between a first position ( FIG. 1 ) wherein piston head  58  is in register with the reduced area portion  54 B of keyhole  54  to a second position ( FIG. 5 ) wherein piston head  58  is in register with the enlarged area portion  54 A of keyhole  54 . As seen in  FIG. 1 , when ball  32  is received in socket  14 , piston  56  is engaged by ball  32  compressing spring  60  in piston housing  66  and piston head  58  is in register with the reduced area portion  54 B of keyhole  54 . As piston head  58  has a larger diameter or size than reduced area portion  54 B, in the position shown in  FIG. 1 , piston head  58  cannot move downwardly through keyhole  54 . Further, in the position shown in  FIG. 1 , concave surface  30  has engaged ball  32  preventing any movement of ball  32  out of socket  14 . 
         [0021]    In the latched or locked position shown in  FIG. 1 , ball  32  cannot dislodge from socket  14  because stop surfaces  36  on frame  28  have engaged stop  38  precluding any movement of concave surface  30  away from ball  32 . In the event that extra safety is desired, lever  44  can be locked in position by means of a safety pin  70  received in a hole  74  in lever  44  and registering holes  72  in housing  12 . 
         [0022]    It will be appreciated that if due to uneven terrain conditions during travel, relative vertical movement occurs between tongues  40  and  13 , ball  32  will exert force against concave surface  30  attempting to force arm  48  to move in a counterclockwise direction around pivot pin  24 . However, as noted such movement is precluded by engagement between stop surface  36  and stop  38 . 
         [0023]    With reference now to  FIG. 5  which shows the trailer hitch of the present invention in the ready or open position, i.e., before ball  32  has been fully received in socket  14 , it can be seen that slide plate  50  has been moved to the position where enlarged portion  54 A of keyhole  54  is in register with piston head  58 . Since piston head  58  is of a smaller diameter or area than the area of enlarged portion  54 A, it has been pulled downwardly, i.e., in the direction of socket  14 , by the action of spring  60  forcing piston  56  into socket  14 . As can also be seen, the manual movement of lever  44  in the direction of arrow  46  to permit release of ball  32  from socket  14  tilts stop bar  38  downwardly out of engagement with stop shoulders  36  such that frame  28  can now move to a disengaged position relative to ball  32  allowing ball  32  to exit or enter socket  14 . The tilting of stop  38  results in disengagement of shoulders  36  with stop  38  thereby permitting frame  28  to move away from socket  14 . It will be noted that arm  48  has also been pivoted around pin  24  towards lever  44  further compressing spring  22 . 
         [0024]    When ball  32  is completely out of socket  14 , spring  22  is unable to rotate lever  44  back into the latched or closed position of  FIG. 1  because piston head  58  is now in enlarged portion  54 A of keyhole  54  meaning that slide plate  50  is substantially precluded from horizontal movement e.g. to the right as best seen with reference to  FIG. 6 . 
         [0025]    When it is desired to connect ball  32  to the trailer hitch of the present invention, ball  32  enters cavity  14  where it engages piston  56  compressing piston  16  and moving head  58  out of the enlarged portion  54 A of keyhole  54 . Thus plate  50  can now slide to the right putting head  58  in register with the reduced area portion  54 B of keyhole  54 . In response, spring  22  rotates arm  48  of keeper  18  in a clockwise direction thereby moving concave face  30  of frame  28  toward socket  14 . As ball  32  completely enters socket  14 , spring  22  can now fully expand allowing arm  48  to rotate clockwise to the point where block  38  is once again engaged by stop shoulders  36 . At such time that piston  56  moves upwards and piston head  58  exits keyhole  54 , slide plate  50  will be kept down by keepers or dogs  64  attached to the side of piston housing  66 . 
         [0026]    As noted above, to ensure that when the draft vehicle and the trailer are attached, and as an additional safety measure, pin  70  can be inserted through holes  72  and  74  to ensure that the mechanism remains locked under all circumstances. 
         [0027]    Instead of a simple pin, a special locking pin as shown in  FIG. 3  can be employed. In this regard, pin  80 , shown in phantom, can be provided with a key operated lock  82  which is slid over a serrated portion of pin  80  in racket-like fashion until enlarged portion  72  of pin  80  is pulled against housing  12  around hole  72  at which point lock  82  can be locked by locking lock  82 . 
         [0028]    Pin  80  can also be provided with a signal emitting mechanism or alarm  84  which will only stop when the pin is installed indicating a secure hitch. In this regard to prevent installation of pin  80  into an open, unsecured hitch, holes  72  of housing  12  can be blocked by a protrusion  86  (see  FIG. 5 ) on lever  44  when the hitch is in the open position. 
         [0029]      FIG. 7  shows an alternate locking device, indicated as  100 , that can be used to ensure that lever  44  remains in its locked position. A hook  102  is pivotally attached to lever  44  by means of a pivot pin  104  which is urged into clockwise rotation by a torque spring  106 , hook  102  engaging stop pin  108  on lever  44 . During the hitching process, it will be seen that the distal end  110  of hook  102  slides up on a ramp  112  of an upward facing protrusion  114  of housing  12  and drops into engagement under the edge  116  of protrusion  114  thereby preventing accidental counterclockwise rotation of lever  44 . During the disengagement process, thumb pressure against extension  120  of hook  102  in the direction of arrow  122  results in counterclockwise rotation of hook  102  moving end  110  out from under edge  116  which permits counterclockwise rotation of lever  44 . 
         [0030]    The foregoing description and examples illustrate selected embodiments of the present invention. In light thereof, variations and modifications will be suggested to one skilled in the art, all of which are in the spirit and purview of this invention.