Abstract:
A lunette trailer hitch lock prevents theft of trailers and other objects equipped with a lunette-style trailer coupler hitch having a lunette eye. The lock device has a top member and a bottom member which are engageable with each other. A conventional step in lock can be used to lock the top member and the bottom member together while sandwiching and plugging the lunette eye, thereby preventing any attempt to access the lunette trailer hitch.

Description:
BACKGROUND 
     The present invention relates to a lock device. More particularly, the present invention relates to an apparatus for preventing theft of trailers equipped with a lunette-style trailer coupler hitch. 
     Trailers and equipments employing the lunette trailer hitch are susceptible to theft. They are easily stolen because of the rather simple method(s) by which they can be towed. Besides being towed by a vehicle utilizing the appropriate hitch, these objects can also be towed by any vehicle simply using a strong rope or chain. 
     Many devices have been employed in an attempt to prevent the theft of objects equipped with lunette hitch. The simple premise of these items has been to plug the center of the lunette hitch or lunette eye so nothing can pass through it in order to couple the attached trailer, equipment, or any other device to a towing vehicle. 
     The existing devices, however, have numerous shortcomings. The two most common shortcomings are: (1) structural weakness of the device; and (2) exposed arrangement of the locking mechanism. Many of the existing devices are not structurally strong enough to guard against common burglary tools such as pry bars, bolt cutters, sledgehammers, torches, and hacksaws. They also leave the lock or locking mechanism exposed to thieves for easy access in order to defeat the locking device. 
     Some of the existing devices are too costly to manufacture. Some of the devices are too complex, while some are too simple to defeat. 
     Therefore, there is a need to provide a lunette trailer hitch lock having strong structural integrity to prevent the locking mechanism from being defeated. Additionally it is desirable to provide a lunette trailer hitch lock which does not leave the lock or locking mechanism exposed for easy access. It is also very desirable to provide a lunette trailer hitch lock which is extremely durable yet inexpensive to produce. Finally, it is also very desirable to provide a lunette trailer hitch lock which is simple to use yet tough to defeat. 
     SUMMARY 
     In one embodiment of the present invention, the lock device has a top member having a raised wall, an internal circular aperture, and a bottom surface including a slot. The lock device also has a bottom member having an upper portion, a lock engaging tang extending from the upper portion, and a bottom portion. The top and bottom members are engageable with each other, such that the slot allows the lock engaging tang to be inserted therein and to protrude within the internal circular aperture. 
     In another embodiment of the present invention, the bottom member and the top member of the lock device are made of cast iron. 
     In yet another embodiment of the present invention, the bottom member and the top member are made of cast aluminum. 
     In still yet another embodiment of the present invention, the bottom member and the top member are made of cast alloys. 
     In another embodiment of the present invention, the top member engulfs a conventional step in lock, one of which is sold under the trademark, American Lock™ (for example, Model No: 2010), such that upon locking the conventional step in lock, the conventional lock engages the lock engaging hardened tang and access to the conventional lock is hindered, thereby making any attempt to breach the conventional step in lock very difficult. 
     In yet another embodiment of the present invention, the upper and the lower members are made of a material with a predetermined strength, such that cutting through said members is made very difficult. 
     Therefore, the present invention satisfies the long felt need to provide a lunette trailer hitch lock having strong structural integrity to prevent the locking mechanism from being defeated. Additionally the present invention satisfies the long felt need to provide a lunette trailer hitch lock which does not leave the lock or locking mechanism exposed for easy access by unauthorized persons. The present invention also satisfies the long felt need to provide a lunette trailer hitch lock which is extremely durable yet inexpensive to produce. Finally, the present invention satisfies the long felt need to provide a lunette trailer hitch lock which is simple to use yet tough to damage. 
    
    
     DRAWINGS 
     These and other features, aspects, and advantages of the present invention will be better understood from the following drawings, description and appended claims, where: 
     FIG. 1 illustrates a preferred embodiment of the entire device of the present invention that is engaged in a lunette trailer hitch. 
     FIG. 2A illustrates a back view of a step in lock that is used in conjunction with the present invention, in its locked state. 
     FIG. 2B illustrates a back view of a step-in lock that is used in conjunction with the present invention, in its unlocked state. 
     FIG. 3 illustrates a top view of a preferred embodiment of the top of the present invention having a protective ring that encompasses the step-in lock as shown in FIG. 2, and a step-in device. 
     FIG. 4 illustrates a side view of a preferred embodiment of the bottom of the present invention having a hardened tang and a base. 
     FIG. 5 illustrates an engaging sequence of a preferred embodiment of the entire device of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following discussion describes in detail one embodiment of the invention and several variations of that embodiment. This discussion should not be construed, however, as limiting the invention to those particular embodiments. Practitioners skilled in the art will recognize numerous other embodiments as well. For a definition of the complete scope of the invention, the reader is directed to the appended claims. 
     The present invention addresses all of the concerns mentioned above. While the present invention plugs the lunette eye or the hole in the center of the lunette hitch to prevent coupling with a towing vehicle as with any other existing lock devices, this invention is novel and different from other devices in that it is structurally far stronger. A preferred embodiment of the present lunette lock device is made of solid cast iron with substantial thickness that it would take an enormous amount of time to cut through with a hacksaw or chainsaw. The present invention can also be made of other metals such as aluminum, stainless steel, titanium, or any of the alloys thereof. 
     Additionally, the present lock device is extremely resistant to high heat such as torch flames. The metal composition that makes up the lunette lock device tends to bubble when subjected to a torch flame. Application of a torch to defeat this lock device could very well make it more difficult to remove this lock device from the attached object. 
     In addition, sledgehammers and similar impact tools will not break the instant invention. It is estimated that a healthy, 200-pound adult male could repeatedly strike the present device with an 8-pound sledgehammer for a substantial amount of time without compromising the integrity of the device, based on the experiment conducted by the inventors. More importantly, there are no exposed areas that could be susceptible to bolt cutters to disengage the locking mechanism. Prying devices have no significant area of opportunity in which to apply pressure to the present invention. 
     The instant lock device is highly unique because it protects the locking mechanism itself. The round, raised wall protects the lock in the center of the device. The lock itself is encompassed by the device and the locking shaft is hidden from view. The lock is not exposed to any threats of prying or cutting. 
     In FIG. 1, a lock device  10  is shown in its entirety and engaged with a lunette trailer hitch drawn in broken lines. The lock device  10  engages with the lunette trailer hitch in a manner such that the opening of the lunette trailer hitch, or the lunette eye, is completely plugged with the lock is device  10  and any attempt to engage the lunette trailer hitch is thereby prevented. 
     FIG. 2A shows a bottom view of a step in lock in locked state  20 , while FIG. 2B shows a bottom view of a step in lock in unlocked state  30 . The step in lock engages with the lock device  10  of the present invention at a lock insert  24 . The lock device  10  is shaped such that it accommodates a step in bottom  25  of the step in lock to form a secure juncture. The step in lock secures the lock device  10  when a key  23  is used to engage an extending lock mechanism  22 , such that a bolt  21  protrudes through the lock insert  24  and irremovably engages the lock device  10  that is inserted in the lock insert  24 . 
     FIG. 3 shows a top view of a top member  100  of the present invention. The top member  100  has a raised wall  110 , an internal circular aperture  120 , a raised bottom surface  130 , and a slot  135 . The internal circular aperture  120  is of a sufficient size to accommodate the step in lock of FIG. 2A or  2 B. The raised bottom surface  130  is shaped in a corresponding manner to the step in bottom  25  of the step in lock such that a secure juncture between the step in lock and the top member  100  is made possible. The raised wall  110  encompasses the step in lock when the step in lock is inserted in the internal circular aperture  120  of the top member  100 , such that the raised wall  110  protects the step in lock that is placed inside the top member  100  of the lock device  10  and the extending lock mechanism  22  is hidden from view when the step in lock is locked as in step in lock in locked state  20 . The step in lock is not exposed to any threats of prying or cutting. 
     FIG. 4 shows a perspective view of a bottom member  200  of the present invention, which comprises a lower portion  230 , a cylindrical upper portion  210 , and a lock engaging hardened tang  220  having a central aperture  225 . The cylindrical upper portion  210  of the bottom member  200  is shaped such that it can be inserted through the lunette eye. The lower portion  230  is of a sufficient size larger than a diameter of the lunette eye, thereby stopping the lunette trailer hitch from completely passing through the bottom member  200 . 
     As shown in FIG. 5, the lock engaging hardened tang  220  is capable of being inserted through the slot  135  of the top member  100  and protrudes upward, where the lock engaging hardened tang  220  is further inserted to the lock insert  24  of the step in lock. At this point, when the step in lock is locked, the bolt  21  protrudes into the lock insert  24  and through the central aperture  225  of the bottom member  200 , thereby securely locking the top member  100  and the bottom member  200  together while sandwiching the lunette trailer hitch. 
     A preferred embodiment of the top member  100 , the bottom member  200 , and all of their parts are made of solid cast iron with substantial thickness that it is structurally extremely strong and it would take an enormous amount of time to cut through with a hacksaw or chainsaw. They can also be made of other metals such as aluminum, stainless steel, titanium, or any alloy thereof. Sledgehammers and similar impact tools will not break the top member  100  or the bottom member  200 . It is estimated that a healthy, 200-pound adult male could repeatedly strike the top member  100  of the present device with an 8-pound sledgehammer for at least about eight hours without compromising the integrity of the top member  100  or the bottom member  200  of the present device, based on the experiment conducted by the inventors. 
     Additionally, the top member  100  and the bottom member  200  of the present lock device are extremely resistant to high heat such as torch flames. The metal composition that makes up the lunette lock device tends to bubble when subjected to a torch flame. Application of a torch to defeat this lock device could very well make it more difficult to remove this lock device from attached object. 
     Sledgehammers and similar impact tools will not break the top member  100  or the bottom member  200  of the instant invention, either. It is estimated that a healthy, 200-pound adult male could repeatedly strike the present device with an 8-pound sledgehammer for at least about eight hours without compromising the integrity of the device, based on the experiment conducted by the inventors. There are no exposed areas which expose the step in lock that could be susceptible to bolt cutters. 
     Prying devices have no significant area of opportunity in which to apply pressure to the present invention in order to disengage or remove the step in lock from the present invention.