Abstract:
A locking apparatus for locking the doors of a cargo container, such as the rear doors of a trailer, is disclosed. The locking assembly may include a second tubular member that telescopes and slides within a first tubular member and an L-shaped assembly mounted on or near the ends of the respective first and second tubular members. The locking apparatus may be placed in a perpendicular fashion between the securing rods of the doors of a cargo container, and the tubular members may be slidably telescoped until the L-shaped assemblies substantially fill the spaces between the cam pins of the securing rods and the walls of the cam pin housings containing the cam pins when the securing rods are in a locked position. In this manner, the cam pins will be prevented from being removed from the cam pin housings, thereby preventing the securing rods from rotating, which in turn keeps the doors of the cargo container securely and tightly locked.

Description:
FIELD OF THE INVENTION 
     The present invention relates to locking devices, and more particularly relates to an apparatus for locking the doors of a trailer. 
     BACKGROUND INFORMATION 
     Large enclosed containers for trailers are often used with tractor trucks, railroad flat cars, barges, ships, and the like as a common mode of cargo movement. Large portions of commercial goods are transported in such containers. These goods may range from inexpensive perishables, such as vegetables, to expensive, fragile electronic devices, such as computers. The container itself may be handled by several intermediate transport companies and may be borne by several different vehicles before the goods themselves reach their final destination. For instance, the container may be first borne aboard a tractor trailer, then stacked on an inland waterway barge, then stacked in the hold of an ocean-going ship, later loaded on a railroad flat car, and finally loaded again on a tractor trailer for transport to a local warehouse or store. 
     The containers themselves often have rear or side doors for access, which are built in accordance with a relatively common standard. These doors normally open outward, and contain large rotating vertical securing rods that are affixed to the doors and can be used to latch and secure the doors in a substantially closed position. One or more of these vertical rods are normally affixed to each door in aligned sockets to permit rod rotation. These vertical rods are normally mounted parallel to one another, and near the edges of the doors where the doors abut together and overlap when in the closed position. 
     When the rods are rotated to a “closed” position, cam pins near the upper and/or lower ends of the vertical rods latch within and against open box-like receptacles or housings mounted to the top and/or bottom frame edges of the container so that the doors may be tightly closed. Handles on the rods may be pulled upward from their normal positions and then used to rotate the rods. Therefore, when the doors are closed, an operator may rotate the rods to clasp the doors down tightly, lifting the handles when the rods are almost in their locked position and dropping the handles into latches in the face of the trailer door. This latching feature is meant to prevent the vertical rods from rotating once the doors are tightly closed. Padlocks or other similar locking devices are often used to lock these vertical rods into closed position. 
     Unfortunately, theft has become a major problem with such containers because of the manner in which they are used. Such containers are frequently left unattended for varying periods of time in storage facilities, or on railroad flat cars during transportation from one site to another. Thieves can easily break open the container doors and gain access to the goods inside by using pry bars, hammers, saws and other similar tools to break the locks on the vertical rods, thereby enabling the vertical rods to be pivoted to their open position, and consequently allowing the doors to be opened. 
     Various devices have been developed in an attempt to make it more difficult to break into such containers. Many of these devices consist of bars or rods that stretch across the doors of the container and lock into place, thereby blocking the doors and keeping them from opening. Some devices actually wrap around at least two of the vertical securing rods, thereby preventing the doors and their respective securing rods from separating. Most of these devices are expensive, cumbersome and difficult to manufacture and use. Furthermore, many of these devices still allow opportunities for thieves to circumvent them and break into the containers. 
     There is identified, therefore, a need for an improved locking device for the doors of trailers and other storage containers that overcomes disadvantages, shortcomings, or limitations of known locking devices for the doors of trailers and other storage containers. 
     SUMMARY OF THE INVENTION 
     An aspect of the invention is to provide an apparatus for locking the doors of a trailer, the doors having at least two securing rods for securing the door to the frame of the trailer, and the securing rods each including at least one cam pin attached near an end of the securing rod and the frame including one cam pin housing for cooperation with at least one of the cam pins. The apparatus includes a first tubular member, and a second tubular member structured and arranged to be received within the first tubular member, wherein the first and second tubular members each include means for engaging the cam pins to substantially prevent movement of the securing rods. 
     Another aspect of the present invention is to provide a trailer door assembly including at least two securing rods for securing the door assembly to a frame of a trailer, at least one cam pin attached near an end of at least one of the securing rods, at least one cam pin housing for cooperation with at least one of the cam pins, a first tubular member, and a second tubular member structured and arranged to be received within the first tubular member, wherein the first and second tubular members each include means for engaging the cam pins to substantially prevent movement of the securing rods. 
     A further aspect of the present invention is to provide a method of locking the doors of a trailer, the doors including at least two securing rods for securing the doors to a frame of the trailer, the securing rods each including at least one cam pin attached near an end of a securing rod, and the frame including at least one cam pin housing for cooperation with at least one of the cam pins. The method includes providing a locking apparatus, wherein the locking apparatus includes a first tubular member, a second tubular member structured and arranged to be received within the first tubular member, and wherein the first and second tubular members each include an L-shaped assembly comprising a base plate and a retaining plate extending generally outward from the base plate for engaging the cam pins to substantially prevent movement of the securing rods, placing the first and second tubular members between at least two of the securing rods in a substantially perpendicular position with respect to the securing rods, slidably positioning the first tubular member within the second tubular member so that each retaining plate substantially fills a gap between the cam pin and the wall of the cam pin housing, thereby preventing the cam pin from being removed from the cam pin housing, and securing the second tubular member within the first tubular member in a substantially locked position. 
     These and other aspects of the present invention will be more apparent from the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a  is an isometric view of a portion of a locking apparatus in accordance with an embodiment of the present invention. 
     FIG. 1 b  is an isometric view of a portion of a locking apparatus in accordance with an embodiment of the present invention. 
     FIG. 2 is an isometric view of a locking apparatus in a substantially unlocked position in accordance with an embodiment of the present invention. 
     FIG. 3 is an isometric view of a locking apparatus in a substantially locked position in accordance with an embodiment of the present invention. 
     FIG. 4 is a partially schematic view of the rear doors of a tractor-trailer in accordance with an embodiment of the present invention. 
     FIG. 5 is a partially schematic view of a portion of the rear door of a tractor-trailer of FIG. 4, showing a portion of a securing rod, a cam pin, and a cam pin housing in accordance with an embodiment of the present invention. 
     FIG. 6 is a partially schematic view of the rear doors of a tractor-trailer, showing the locking apparatus being placed in position in accordance with an embodiment of the present invention. 
     FIG. 7 is a partially schematic view of the rear doors of a tractor-trailer, showing the locking apparatus of FIG. 6 placed in a substantially locked position in accordance with an embodiment of the present invention. 
     FIG. 8 is a partially schematic close-up view of a rear door of a tractor-trailer, showing a portion of a locking apparatus engaged with a cam pin of a securing rod in accordance with an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 a - 3  illustrate an apparatus for locking the doors of a trailer in accordance with an embodiment of the present invention. Although the apparatus of the present invention is primarily described as being used to lock the doors of a trailer, the apparatus may be used for locking the doors of other cargo containers, such as storage containers transported by boats, trains and other suitable vehicles, and such uses are within the scope of the present invention. As will be described in more detail herein, the locking apparatus may be used to lock the doors of a trailer wherein the doors include at least two securing rods for securing the doors to a frame of the trailer. The securing rods may each include at least one cam pin attached near an end of the rod, and the frame may include at least one cam pin housing for receiving and cooperating with a cam pin. The securing rods may contain handles for causing the rods to rotate, and the rods may be rotated so as to cause a cam pin to be received within a cam pin housing. As the cam pin is received within the cam pin housing, the door will be pulled tightly against the frame of the trailer or other cargo container. The locking apparatus of the present invention may be used to prevent the cam pins from being removed from the cam pin housings, thereby preventing the securing rods from rotating out of the locked position. 
     FIG. 1 a  shows that the locking apparatus  10  may include a first substantially hollow tubular member  12 . The first substantially hollow tubular member  12  may include means for engaging a cam pin  40  or  41  (FIG. 4) to substantially prevent movement of a securing rod  34  or  35  (FIG.  4 ), such as an L-shaped assembly  16 . However, it will be appreciated that other means for engaging a cam pin to substantially prevent movement of a securing rod may be used in conjunction with the invention, as claimed and disclosed herein. More specifically, as illustrated in FIG. 1 a , the L-shaped assembly  16  may include a base plate  18  and a retaining plate  20  extending generally outward from the base plate  18 . As shown in FIGS. 1 a - 3 , a longitudinal axis  22  may be defined as an axis that runs substantially parallel to the first substantially hollow tubular member  12  and a second tubular member  14 . In this embodiment, the retaining plate  20  of the L-shaped assembly  16  may extend outward from the apparatus in a direction substantially parallel to the longitudinal axis  22 . The L-shaped assembly  16  may be attached to the tubular member  12  with any suitable fastening means, such as welding or mechanical fasteners. Alternatively, the L-shaped assembly  16  may be formed as an integral part of the tubular member  12  during manufacture. 
     FIG. 1 b  shows that the locking apparatus  10  may include a second tubular member  14 . The second tubular member  14  may include means for engaging a cam pin  40  or  41  to substantially prevent movement of a securing rod  34  or  35 , such as an L-shaped assembly  17 . However, it will be appreciated that other means for engaging a cam pin to substantially prevent movement of a securing rod may be used in conjunction with the invention, as claimed and disclosed herein. More specifically, as illustrated in FIG. 1 b , the L-shaped assembly  17  may include a base plate  19  and a retaining plate  21  extending generally outward from the base plate  19 . The retaining plate  21  may extend outwardly from the apparatus  10  in a direction substantially parallel to the longitudinal axis  22  of the apparatus. The L-shaped assembly  17  may be attached to the tubular member  14  with any suitable fastening means, such as welding or mechanical fasteners. Alternatively, the L-shaped assembly  17  may be formed as an integral part of the tubular member  14  during manufacture. 
     As shown in FIGS. 2 and 3, the second tubular member  14  may be structured and arranged to be received within the first substantially hollow tubular member  12 . As also shown in FIGS. 2 and 3, at least a portion of the second tubular member  14  may be slidably adjustable within the first substantially hollow tubular member  12 . As shown in FIG. 2, the second tubular member  14  may be slidably adjusted within the first tubular member  12  to an unlocked position, and as shown in FIG. 3, the second tubular member  14  may be slidably adjusted within the first tubular member  12  to a locked position. However, the “locked” and “unlocked” positions of the tubular members may be completely variable, depending upon, for example, the size and orientation of the door or doors being locked and the position of the securing rods relative to each other. As used herein, “locked position” means that the second tubular  14  member is slidably adjusted within the first tubular member  12  so that the retaining plates  20  and  21  prevent cam pins, such as the cam pins  40  and  41 , from being removed from their respective cam pin housings, such as cam pin housings  42  and  43 . As used herein, “unlocked position” means that the second tubular member  14  is slidably adjusted within the first tubular member  12  to any position other than a locked position. As shown in FIG. 3, the length L 2  of the apparatus in a locked position is greater than the length L 1  of the apparatus in an unlocked position, as shown in FIG. 2, with respect to longitudinal axis  22 . 
     As shown in FIGS. 1-3, the locking apparatus  10  may include means for locking the apparatus in a locked position, such as a push-button lock assembly  24 . However, it will be appreciated that other means for locking the apparatus in a locked position may be used in conjunction with the invention, as claimed and disclosed herein. In one embodiment, the first tubular member  12  may include a lock housing  26  and the push-button lock assembly  24  may be mounted in a lock-mounting hole  28  formed in the first tubular member  12 . As most clearly shown in FIG. 1 b , the second tubular member  14  may include one or more lock receiving holes  30  for receiving at least a portion of the push-button lock assembly  24 . 
     As illustrated in FIG. 4, the locking apparatus  10  of the present invention may be used to lock the doors of a storage container, such as the rear doors  32  and  33  of a trailer. The rear door  32  may include a securing rod  34 , including at least one cam pin  40  attached near an end  36  of the securing rod  34 , and the frame may include cam pin housing  42  for receiving and cooperating with the cam pin  40  of the securing rod  34 . FIG. 4 also illustrates that rear trailer door  33  may include a securing rod  35  having at least one cam pin  41  attached near an end  37  of the securing rod  35 . A cam pin housing  43  may be attached to the frame  38  of the trailer for receiving and cooperating with the cam pin  41 . Although not shown, securing rods  34  and  35  may include additional cam pins for cooperating with additional cam pin housings attached to other locations on the frame  38 . As most clearly shown in FIG. 5, in order to open a door, such as the rear trailer door  33 , a securing rod, such as the securing rod  35 , may be rotated in a clockwise direction by grasping and pulling the handle  48 , thereby causing the cam pin  41  to be released from the opening  45  of the cam pin housing  43 , and allowing the trailer door  33  to move freely. To tightly close a trailer door, such as the trailer door  33 , the securing rod  35  may be rotated in a counter-clockwise direction by grasping and pushing the handle  48 , thereby causing the cam pin  41  to be cooperatively received within the opening  45  of the cam pin housing  43 , thereby tightly pulling the trailer door  33  against the frame  38 . 
     As shown in FIGS. 6-8, the locking apparatus  10  may be used to prevent rear trailer doors  32  and  33  from opening. As shown in FIG. 6, the first tubular member  12  and the second tubular member  14  may be placed between the securing rods  34  and  35  in a substantially perpendicular position with respect to securing rods  34  and  35 , and the second tubular member  14  may be slidably positioned within the first tubular member  12  in a locked position so that the retaining plate  21  substantially fills a first gap  46  between the cam pin  40  and a wall  44  of the cam pin housing  42 , thereby preventing the cam pin  40  from being removed from the cam pin housing  42 , and retaining plate  20  substantially fills a second gap (not shown) between the cam pin  41  and a wall (not shown) of the cam pin housing  43 , thereby preventing the cam pin  41  from being removed from the cam pin housing  43 , as most clearly illustrated in FIGS. 7 and 8. By preventing cam pins  40  and  41  from being removed from cam pin housings  42  and  43 , securing rods  34  and  35  will not be able to rotate, and trailer doors  32  and  33  will be securely and tightly locked. 
     Once the second tubular member  14  is slidably positioned within the first tubular member  12  so that the cam pin  40  is securely retained within the cam pin housing  42 , as shown in FIG. 8, and the cam pin  41  is securely retained within the cam pin housing  43 , the locking apparatus  10  will be in a locked position, and the second tubular member  14  may be secured within the first tubular member  12  in this locked position, for example, with the push-button lock assembly  24 . In order to remove the locking apparatus  10  from the rear trailer doors  32  and  33 , the second tubular member  14  may be slidably positioned within the first tubular member  12  until retaining plates  20  and  21  are substantially removed from cam pin housings  42  and  43 . The locking apparatus  10  may then be easily removed, and securing rods  34  and  35  will be free to rotate, thus allowing the rear trailer doors  32  and  33  to open. 
     In one embodiment, first tubular member  12 , second tubular member  14 , L-shaped assemblies  16  and  17 , and lock housing  26  may be made of metal or metal alloys, such as steel or iron. However, these portions of the locking apparatus  10  may be made out of other suitable materials having the requisite strength and stability, and such materials are within the scope of the present invention. 
     Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.