Patent Abstract:
A removable locking device for attaching a base ladder to one or more flys of an extension ladder is disclosed herein. The removable locking device is slightly greater in width than the extension ladder. This allows the locking device to simultaneously grasp both the left and right sides of both the base extension ladder and the additional fly extension ladders. The side rails comprise cavities for a plurality of rungs of the extension ladder. The locking device contains insertion pins for engaging the rung cavities along the side rails of the ladders. The locking device contains a further clamping mechanism to engage the base ladder with the fly extension ladder and to secure the insertion pins within the rung cavities of both ladders. With the clamping mechanism engaged, the base extension ladder and the fly extension ladders become locked together, temporarily creating a single securely engaged ladder.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61/865,561, filed Aug. 13, 2013. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to locking devices for securely attaching sections of an extension ladder together and, more particularly, to a locking device for providing a safer solution for securely attaching an additional extension ladder or section of it, to an existing extension ladder to increase the existing ladder&#39;s reach. 
       BACKGROUND OF THE INVENTION 
       [0003]    In the past, construction workers and some general users discovered that sometimes extension ladders available in the market are not long enough to accomplish certain tasks. With the increasing trend of building larger houses, taller buildings, and the like, the use of forty foot extension ladders has become a common activity. Unfortunately, ladders taller than this size are frequently needed and are rarely available in the work place. To overcome this impediment a common practice among professionals is the use of ropes to attach a single section or to fasten two extension ladders together to reach the desired length. This practice is forbidden by regulating authorities, but in most cases these regulations only apply to companies and not to individual users. This unconventional practice, however, sometimes creates an uncomfortable feeling in users, who might fear that an accident might occur. Despite this, and because of circumventable regulations, people still engage in this risky practice because they know that they cannot be cited for this practice unless they have employees. 
         [0004]    Painters and other construction professionals and tradespeople learned that on many occasions the extension ladders available in the market or in the workplace are not tall enough to perform certain tasks. Even for professionals,  36 ′ and  40 ′ extension ladders are difficult to maneuver and transport. The use of two smaller ones instead, enhances the portability, storage and cost aspects. Furthermore, smaller size ladders are unlikely to bend when they fall, and generally the combination of two of them will suffice to accomplish most of the jobs. In unconventional but ingenious ways, construction professionals have figured out that attaching two extension ladders together with ropes, or nailing boards on the roofs to secure the extension ladders, could help them to reach places at greater heights. These methods, in addition to being dangerous, often scare clients, who do not want accidents happening on their properties. However, despite the regulations to avoid misuse of ladders, and the inconvenience caused to property owners, these risky actions are performed on a daily basis. On other occasions, construction professionals sometimes decline jobs involving work in areas unreachable with conventional extension ladders, even if the amount of work in these areas will be minimal compared with the complete project, to avoid such risks. The present invention not only solves these problems, but eliminates others. For example, the embodiments of the present invention may eliminate the necessity to buy the heavy long extension ladders, which are difficult to store and transport. The present invention eliminates all these problems and creates many more advantages. 
         [0005]    The present invention meets one or more of the above-referenced needs as described herein in greater detail. 
       SUMMARY OF THE INVENTION 
       [0006]    Embodiments disclosed herein relate to a Removable Lock For Attaching Additional Extension Ladder Sections. More particularly, the embodiments herein disclose a locking device to provide a safer solution for attaching an additional extension ladder, or a section of it, to another extension ladder to increase its reach. Briefly described, aspects of the present embodiments include the following. 
         [0007]    A removable locking device for attaching a base ladder to one or more flys of an extension ladder is disclosed herein. The removable locking device is slightly greater in width than the extension ladder. This allows the locking device to simultaneously grasp both the left and right sides of both the base extension ladder and the additional fly extension ladders. The side rails comprise cavities for a plurality of rungs of the extension ladder. The locking device contains insertion pins for engaging the rung cavities along the side rails of the ladders. The locking device contains a further clamping mechanism to engage the base ladder with the fly extension ladder and to secure the insertion pins within the rung cavities of both ladders. With the clamping mechanism engaged, the base extension ladder and the fly extension ladders become locked together, temporarily creating a single securely engaged ladder. 
         [0008]    In a further embodiment, the locking device uses spring-loaded insertion pins to engage the rung cavities along the side rails of the extension ladder. The locking device uses dual sets of spring-loaded insertion pins on the left and right sides of the locking device to simultaneously engage the rung cavities along the side rails of both the base extension ladder as well as the joined fly extension ladder. The locking device can further utilize brackets to align the rungs of the fly extension ladder with the base extension ladder for additional stability and engagement with the locking mechanism. 
         [0009]    In still another embodiment, the locking device uses a clamping jaw to firmly engage the rungs while the inserting pins are inside cavities of the extension ladder rungs such that the base ladder and the fly extension ladder are firmly locked together. Alternatively, the locking device can use a threaded screw clamp to engage the rungs of the ladder such that the base ladder and the fly extension ladder are firmly locked together. In still another embodiment, the locking device uses a “U” shaped brace to simultaneously engage aligned rungs of the base ladder and the fly extension ladder along with the clamping mechanisms to temporarily create a stable and secured elongated extension ladder. 
         [0010]    The above features as well as additional features and aspects of the present invention are disclosed herein and will become apparent from the following description of preferred embodiments of the present invention. 
         [0011]    This summary is provided to introduce a selection of aspects and concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The foregoing summary, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the embodiments, there is shown in the drawings example constructions of the embodiments; however, the embodiments are not limited to the specific methods and instrumentalities disclosed. In the drawings: 
           [0013]      FIG. 1   a  is a perspective view of a removable ladder extension lock securely attaching multiple extension ladders together according to an embodiment; 
           [0014]      FIG. 1   b  is a close-up perspective view of the removable ladder extension lock securely attaching multiple extension ladders together according to an embodiment; 
           [0015]      FIG. 2  is an internal view of the removable ladder extension lock according to an embodiment; 
           [0016]      FIG. 3  illustrates a removable ladder extension lock incorporating “U” brackets in accordance with a second embodiment of the invention; 
           [0017]      FIG. 4  illustrates a cross-sectional view of a removable ladder extension lock incorporating a second pair of inserting pins in accordance with a third embodiment of the invention; 
           [0018]      FIG. 5  illustrates a cross-section view of the removable ladder extension lock illustrated in  FIG. 4  in accordance with a third embodiment of the invention; 
           [0019]      FIG. 6  illustrates a cross-sectional view of the removable ladder extension lock incorporating a locking bolt and jaw mechanism in accordance with a fourth embodiment of the invention; 
           [0020]      FIG. 7  is a later lateral cross-sectional view of the removable ladder extension lock illustrated in  FIG. 6  in accordance with a fourth embodiment of the invention; and 
           [0021]      FIG. 8  is a cross-sectional view of the removable ladder extension lock that incorporates a latch for securely clamping the inner portion of a ladder&#39;s side rail in accordance with a fifth embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Before the present methods and systems are disclosed and described in greater detail hereinafter, it is to be understood that the methods and systems are not limited to specific methods, specific components, or particular implementations. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects and embodiments only and is not intended to be limiting. 
         [0023]    As used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Similarly, “optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and the description includes instances where the event or circumstance occurs and instances where it does not. 
         [0024]    Throughout the description and claims of this specification, the word “comprise” and variations of the word, such as “comprising” and “comprises,” mean “including but not limited to,” and is not intended to exclude, for example, other components, integers or steps. “Exemplary” means “an example of” and is not intended to convey an indication of preferred or ideal embodiment. “Such as” is not used in a restrictive sense, but for explanatory purposes. 
         [0025]    Disclosed herein are components that can be used to perform the disclosed methods and systems. It is understood that when combinations, subsets, interactions, groups, etc. of these components are disclosed that although specific reference to each various individual and collective combinations and permutations cannot be explicitly disclosed, each is specifically contemplated and incorporated herein, for all methods and systems. This applies to all aspects of this specification including, but not limited to, steps in disclosed methods. Thus, if there are a variety of additional steps that can be performed it is understood that each of the additional steps can be performed with any specific embodiment or combination of embodiments of the disclosed methods. 
         [0026]    Turning now to  FIG. 1 , an exemplary embodiment  100  of the present invention is illustrated.  FIG. 1  illustrates a base extension ladder  110  having a plurality of rungs  140  placed between the ladder&#39;s side rails  160  for reaching the height of the ladder. Connected to the base extension ladder  110  are a plurality of extension ladder flys  120  and  130  that allow the height of the base extension ladder to be extended. Each rung  140  of the base extension ladder  110  and the extension ladder flys  120  and  130  has a hollow rung cavity  150  opening which helps to reduce the weight of the ladders. In the exemplary embodiment, the removable locking device  170  takes advantage of these rung cavities  150  by inserting locking pins within these cavities, which allow two or more extension ladders to be joined together as explained below. 
         [0027]    The removable locking device  170  is illustrated in greater detail in  FIG. 2 . The removable locking device  170  features a number of components that connect to a connection rod  12  that forms the foundation of the device. The connection rod  12  is slightly greater in width than the base extension ladder  110  and the extension ladder flys  120 - 130 . In an exemplary embodiment, this connection rod  12  has a shape that is substantially similar to the rungs  140  of the extension ladders  110 - 130 . When the removable locking device is attached, the connection rod  12  rests against and effectively creates an extension to one of the rungs on the ladders  110 - 130 . On both the left and right sides of the connection rod  12  are end caps  13  that protect the interior mechanism of the removable locking device  170 . The interior mechanism includes a flange  14  for compressing a spring  15  between the flange  14  and the end caps  13  of the removable locking device  170 . The flange  14  is further connected to a shaft  16  that connects to an insertion pin  17  connected to a handle bar  18  for directing the movement of the insertion pin  17  in the direction of movement of the shaft  16  and spring  15 . The springs  15  extend longitudinally around the pair of shafts  16  respectively. Each of the shafts  16  connects independently to the flange  14  on one end, while the other end extends outside the connecting rod  12 , passing through the ends caps to abut with the handle bar  18 . In an exemplary embodiment, the shaft  16  is of sufficient length to allow the insertion pin  17  to clear the sides of the extension ladders  110 - 130  while the handle bars  18  are pulled away from side rails  160  of the ladders  110 - 130 , compressing the spring  15 , and allowing the removable locking device  170  to be attached to two or more ladders  110 - 130 . Although only one insertion pin is illustrated in  FIG. 2 , in an exemplary embodiment, there at least two insertion pins  17  connected to the handle bar  18  as shown in  FIG. 4 . In a further exemplary embodiment, the insertion pins  17  are placed along the handle bar  18  at such a distance that they align with the rung cavities  150  along the side rails of the extension ladders  110 - 130 . The removable locking device  170  is aligned with rungs of the extension ladders  110 - 130  using brackets  19 . In an exemplary embodiment, the brackets  19  are “U” shaped for embracing at least two parallel rungs  140  of the extension ladders  110 - 130 , while the removable locking device  170  is engaged. The combination of the flange  14  and spring  15  forces one or more insertion pins  17  to move in a horizontal direction towards the interior of the rung cavities  150  of the extension ladders  110 - 130 . Furthermore, the insertion pins  17  and brackets  19  can be coated with a non-slip material such as rubber, soft polymers, wood or cork. 
         [0028]    Further in  FIG. 2 , the removable locking device&#39;s  170  insertion pins  17  are operable using a handle bar  18 . The spring loaded mechanism created by the combination of the flange  14 , spring  15 , shaft  16  and handle bar  18  allow the removable locking devices  170  to be clamped onto the extension ladders  110 - 130 . A user operates the device by aligning parallel rungs  140  of at least two extension ladders  110 - 130  together using the brackets  19  while pulling the handle bars  18  away from the extension ladders  110 - 130 , compressing the spring  15 . The user then aligns the insertion pins  17  with the rung cavities  150 , and releases the handle bar  18  such that the insertion pins slide into the rung cavities  150 , joining both the locking device  170  and two or more extension ladders  110 - 130  together. 
         [0029]    Turning now to  FIG. 3 , a top level view of the removable locking device  170  engaging two parallel rungs  140  of two ladders  110 - 130  is illustrated. As discussed above, removable locking mechanism  170  comprises a connecting rod  12 , end caps  13 , shaft  16 , handle bar  18 , insertion rods  17  and “U” shaped brackets  19 . The “U” shaped brackets engage parallel rungs  140  of the ladders  110 - 130  while the insertion pins  17  engage rung cavities  150 , disposed along the side rails  160  of the ladders  110 - 130 , thereby locking the two ladders  110 - 130  together. 
         [0030]    Further to  FIG. 3 , in  FIG. 4 , a top level view of the removable locking device  170  engaging two parallel rungs  140  of two ladders  110 - 130  is also illustrated. As discussed above, removable locking mechanism  170  comprises a connecting rod  12 , end caps  13 , shaft  16 , handle bar  18 , insertion rods  17  and “U” shaped brackets  19 . The “U” shaped brackets engage parallel rungs  140  of the ladders  110 - 130  while the insertion pins  17  engage rung cavities  150 , disposed along the side rails  160  of the ladders  110 - 130 , thereby locking the two ladders  110 - 130  together. However, as illustrated in this embodiment, the handle bar  18  comprises multiple insertion pins  17  for engaging the rung cavities of both the attached ladders  110 - 130 . In an exemplary embodiment, the removable locking device  170  comprises the two insertion pins  17  along its handle bars  18 . However, there could be one, two, three or more insertion pins along each handle bar depending on the need or application. 
         [0031]    Turning now to  FIG. 5 , the side rails  160  of two ladders  110 ,  120  are illustrated. Disposed along the side rails  160  of the two ladders  110 ,  120  are the rung cavities  150 . These cavities are hollowed out openings, similar to metal or fiberglass pipes that make up the rungs  140  of the ladders  110 ,  120 .  FIG. 5  illustrates the engagement of the insertion pins  17  into the cavities  150  and described in the discussion of  FIGS. 3 and 4  above. These insertion pins  17  are connected to the handle bar  18  and shaft  16  such that they align with the rung cavities  150 . These insertion pins  17  may be similar in girth to the rung cavities  150  such that there is a snug fit. In a further embodiment, the insertion pins  17  may comprise a metal rod coated with rubber, plastic, cork or other materials to ensure a snug fit with a variety of openings of the rung cavities  150 . 
         [0032]      FIGS. 6 and 7  illustrate another embodiment of a removable locking device  600  wherein the insertion pins  17  are not spring loaded, but fixed to a handle bar  22 . In this embodiment there are separate removable locking devices  600  for both the right and left sides of the ladders  110 - 130 .  FIG. 6  illustrates the removable locking device  600  engaging one side of the adjoined ladders, by placing the insertion pins into the rung cavities  150  and then using a screw clamp  20  to frictionally engage its jaw  21  with a corresponding rung of the ladders  110 - 130 .  FIG. 7  illustrates a further perspective view of the removable locking device  600 . Illustrated in  FIG. 7 , the jaw  21  of the screw clamp  20  frictionally engages to a rung  140  of ladder  110 , while the insertion pin  17  is inserted into the rung cavity  150  of ladder  120 . This allows both ladders  110  and  120  to be locked together. 
         [0033]      FIG. 8  illustrates still another embodiment of the removable locking device  700 . Here, the insertion pins  17  are also not spring loaded, but fixed to a handle bar  22 . In this embodiment there are separate removable locking devices  700  for both the right and left side of the combined ladders  110 - 130 . The removable locking device  700  engages one side of the adjoined ladders, by placing the insertion pins  17  into the rung cavities  150  and then using a spring latch  25  to frictionally clamp its jaw to the side caps  26  of the ladders  110 - 130 . A second removable locking device  700  engages the other side of the adjoined ladders, by placing the insertion pins into the rung cavities  150  and then using a spring latch  25  to frictionally clamp its jaw to the side caps  26  of the ladders  110 - 130 . 
         [0034]    Although the discussion has generally focused on just one removable locking device  170 ,  600 ,  700  being used in each application, in an embodiment multiple locking devices may be used to engage two or more ladders  110 - 130  along a multiple points to ensure the stability of the adjoined ladders. 
         [0035]    Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Technology Classification (CPC): 4