Abstract:
An improved trailer theft-thwarting coupling dock to prevent unauthorized coupling and hauling of the trailer coupling dock includes a coupling dock body, a upper mechanism, a lower mechanism and a lock assembly. The upper mechanism has a upper handle fastening to the lock assembly. Through locking and unlocking of the lock assembly, unauthorized opening of the upper mechanism can be prevented. Thereby the trailer coupling dock cannot be coupled and hauled unless authorized, and an improved theft-thwarting effect can be achieved for the trailer.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates to an improved trailer theft-thwarting coupling dock and particularly to a trailer theft-thwarting coupling dock to prevent unauthorized coupling and hauling thereof.  
         [0003]     2. Description of the Prior Art  
         [0004]     The conventional trailer coupling dock such the one disclosed in U.S. Pat. No. 6,505,849 has a coupling dock mating a spherical seat to couple with a trailer. The coupling dock has a lever mechanism to actuate a lower latch member beneath the coupling dock to enable the coupling dock and the spherical seat to be separated or latched so that the trailer can be disconnected or connected as desired.  
         [0005]     The conventional trailer coupling dock mentioned above confines the spherical seat in a spherical cap of the coupling dock through the lever mechanism to actuate the lower latch member. The lever mechanism presses the lower latch member at a desired location, but does not have any theft-thwarting structure. Any person can easily disengage the coupling relationship. As a result, the trailer could be stolen and towed away easily.  
       SUMMARY OF THE INVENTION  
       [0006]     In view of the aforesaid disadvantages occurred to the conventional techniques, the present invention aims to provide a trailer coupling dock that cannot be coupled and hauled easily to prevent the trailer from being stolen. The invention includes a coupling dock body, a upper mechanism, a lower mechanism and a lock assembly. The upper mechanism has a handle coupling with the lock assembly. Through locking and unlocking of the lock assembly, unauthorized opening of the upper mechanism can be prevented. Thereby an improved theft-thwarting effect can be achieved.  
         [0007]     The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is an exploded view of the invention.  
         [0009]      FIG. 2  is a sectional view of the invention in an operating condition.  
         [0010]      FIG. 3  is a cross section taken on line I-I in  FIG. 2 .  
         [0011]      FIG. 4  is a cross section taken on line II-II in  FIG. 3 .  
         [0012]      FIG. 5  is a sectional view of the invention showing a unlocking condition.  
         [0013]      FIG. 6  is a cross section taken on line III-III in  FIG. 5 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0014]     Referring to  FIGS. 1 and 2 , the invention includes a coupling dock body  1 , a upper mechanism  2 , a lower mechanism  3  and a lock assembly  4 .  
         [0015]     The coupling dock body  1  has a spherical cap  11  on one side which is extended rearwards to form a coupling portion  12 . The coupling portion  12  has a third axle hole  121  running through thereof transversely close to the spherical cap  11  to receive a third axle A 3 , and a draw bar aperture  122  on a upper side.  
         [0016]     The upper mechanism  2  includes: 
        a upper handle  21  which is hollow and has a housing space  211  inside, a first axle hole  212  and a second axle hole  213  formed respectively on two corresponding sides of the housing space to be run through respectively by a first axle A 1  and a second axle A 2 , and a first fastening hole  214  below the second axle hole  213 ;     a lower handle  22  which has a notch  221  on a upper edge to engage with a first end B 11  of a first spring B 1 , a round hole  222  on a front end corresponding to the first axle hole  212  of the upper handle  21  to be run through by the first axle A 1  and to be latched by a second end B 12  of the first spring B 1 . The first spring B 1  has a third end B 13  to push the upper handle  21 . The lower handle  22  further has a latch hook  223  on a lower side;     a upper latch blade  23  which has a first opening  231  on one side and a second opening  232  on another side. The second opening  232  is latchable by the latch hook  223  of the lower handle  22 ; and     a draw bar  24  which runs through the draw bar aperture  122  of the coupling dock body  1  and is movable therein up and down. The draw bar  23  has a first aperture  241  and a second aperture  242  on a upper portion, and a screw thread portion  243  on a lower portion. The upper portion of the draw bar  24  runs through the first opening  231  of the upper latch blade  23 , and then the first aperture  241  is run through by the second axle A 2 .        
 
         [0021]     The lower mechanism  3  includes a fourth spring B 4 , a lower latch blade  31 , a washer  32 , a fifth spring B 5  and a nut  33  that are coupled on the lower portion of the draw bar  24  in this order. The lower latch blade  31  has an aperture  311  to be run through by the draw bare  24  to fasten to the nut  33 . The lower latch blade  31  has an arched notch  312  on a front edge and a notch  313  on a rear edge to be coupled with the third axle A 3 ;  
         [0022]     The lock assembly  4  includes: 
        a housing  41  which has one end fastened to the handle  21  on the periphery of the first fastening hole  214 , a housing chamber  415 , a second fastening hole  411  corresponding to the first fastening hole  214 , a first pin hole  412  and a second pin hole  413  on a upper side to be coupled respectively with a first pin C 1  and a second pin C 2 , and a third spring B 3  and a detent member  414 ;     a second spring B 2  held in the housing chamber  415  of the housing  41 ;     a lock cylinder  42  which is held in the housing  41  and has one side pressing the second spring B 2 , a third fastening hole  421  on a front side, and a flute  422  on a upper side to be coupled with the first pin C 1  of the housing  41  so that the lock cylinder  42  can slide forwards and rearwards within a confined limit. The lock cylinder  42  further has at least one fastening pin hole  423  to hold a lower fastening pin  4231 , a upper fastening pin  4232 , a spring  4233  and an a fastening pin  4324 ; and     a core  43  which has a locking bolt  431  on a front portion and a key way  433  on a rear end to receive a key. The locking bolt  431  has a detent trough  432  on a upper side. The core  43  further has one or more second fastening pin hole  434  corresponding to the first fastening pin hole  423  of the lock cylinder  42 .        
 
         [0027]     By means of the construction set forth above, the upper handle  21  can be moved upwards and downwards to drive the draw bar  24  up and down. Then the lower latch blade  32  of the lower mechanism  3  can clip a spherical dock  5  in the spherical cap  11  of the coupling dock body  1 , or allows the spherical dock  5  to be separated from the spherical cap  11 . The operation is same as the conventional techniques, details are omitted.  
         [0028]     Referring to  FIGS. 3 and 4 , to lock the upper mechanism  2  through the lock assembly  4 , push the core  43  inwards; the locking bolt  431  runs through, in this order, the third fastening hole  421 , second fastening hole  411 , first fastening hole  214  and second aperture  242  of the draw bar  24 , the detent member  414  in the second pin hole  413  is pushed by the third spring B 1  to wedge in the detent trough  432  of the locking bolt  431  to form a latched condition; then turn the core  43  and remove the key  6  to finish the locking operation. In such a condition, the upper handle  21  and the draw bar  24  are harnessed and cannot be moved upwards. The spherical dock  5  also cannot be separated from the spherical cap  11 . On the other hand, to unlock the lock assembly  4 , referring to  FIGS. 5 and 6 , insert a key  6  into the core  43  and turn the core  43 ; the detent trough  432  of the locking bolt  431  is turned away from the latched condition with the detent member  414 , and the harness condition of the locking bolt  431  is released; the lock cylinder  42  is retracted due to the returning elastic force of the second spring B 2 ; with the first pin C 1  of the housing  41  confined by the flute  422  of the lock cylinder  42 , and the locking bolt  431  is separated from the second aperture  242  of the draw bar  24 , the first fastening hole  214  and second fastening hole  411  of the upper handle  21 , the upper handle  21  of the upper mechanism  2  can be moved upwards as desired. And the spherical dock  5  also can be separated from the spherical cap  11  in the unlocking condition.