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BACKGROUND OF THE INVENTION  
       [0001]     1. Technical Field  
         [0002]     The present invention relates to ladder securement devices for vehicles and, more particularly, to a ladder securement device for use with ladder racks which includes at least one pivot mount adapted to be mounted on a ladder rack and a generally horizontal pivot bar pivotably mounted on the pivot mount which is rotatable about an axis generally defined by the center longitudinal axis of the pivot bar, at least two generally inverted L-shaped ladder-engaging hooks mounted on the pivot bar adjacent opposite ends thereof, the ladder-engaging hooks pivotable between a ladder engaging position and a ladder release position, a handle operatively connected to the pivot bar for rotating the pivot bar about the center longitudinal axis thereof, and the ladder-engaging hooks adapted to extend over and engage a side rail of at least one ladder mounted on the ladder rack when the ladder-engaging hooks are in the ladder engaging position.  
         [0003]     2. Description of the Prior Art  
         [0004]     There are many different types of ladder racks which are used on trucks, cars, and the like, for carrying of ladders to and from various job sites. In general, a ladder rack includes a generally rectangular frame structure mounted above the bed of a pickup truck with ladders being secured to the upper part of the ladder rack so that they may extend forwards and rearwards from the bed of the pickup truck. In most cases, the ladder is secured to the ladder rack by straps, tie-downs or the like, although there are other devices which can be used for securement of a ladder on a ladder rack. For example, one may use a clamping device to secure the ladder on the ladder rack or any other type of appropriate securement device. A clear disadvantage of the use of such tie-downs, clamps and the like is that one must climb the side of the ladder rack to the elevated position where the ladder is mounted in order to properly secure the ladder on the ladder rack. Accessing the top of the ladder rack to secure the ladder can be a dangerous and risky proposition and therefore there is a need for a ladder securement device for use with ladder racks which will not require the user to access the top of the ladder rack structure to secure the ladder thereon.  
         [0005]     There are several different types of ladder securement devices found in the prior art, including such devices as shown in Sexton, U.S. Pat. No. 5,398,778, and Bradley, et al., U.S. Pat. No. 6,315,181. The vast majority of these devices, however, have one thing in common and that is that they secure ladders by engaging the rungs of the ladder which provides an inherently unstable mounting location on a ladder. For example, as the majority of ladder rungs on extendable ladders are at least semi-cylindrical in shape, it is far easier for the ladder securement element of those devices found in the prior art to slide off of the ladder rung, thus releasing the ladder to cause damage as it falls from the ladder rack. Another problem with those devices found in the prior art is that they often require multiple steps to secure the ladder on the ladder rack, such as fastening separate fastening elements to the ladder instead of being able to secure the ladder on the ladder rack in one convenient step. There is therefore a need for an improved ladder securement device for a ladder rack which will address and correct each of the problems not solved by the prior art and do so in a safe and efficient manner.  
         [0006]     Therefore, an object of the present invention is to provide an improved ladder securement device for a ladder rack.  
         [0007]     Another object of the present invention is to provide an improved ladder securement device for a ladder rack which includes a single pivot bar on which two or more ladder-engaging hooks are mounted, the ladder-engaging hooks operative to rotate with the pivot bar to engage a side rail of a ladder mounted on the ladder rack when the ladder-engaging hooks are in the ladder engaging position.  
         [0008]     Another object of the present invention is to provide an improved ladder securement device for a ladder rack which may be used with virtually any type of ladder so long as the ladder includes at least one side rail for the ladder-engaging hooks to engage.  
         [0009]     Another object of the present invention is to provide an improved ladder securement device for a ladder rack which includes a handle operatively connected to the pivot bar to rotate the pivot bar between the ladder engaging position and ladder release position such that the device may be operated by a person standing on the ground adjacent the ladder rack instead of requiring the person to climb the ladder rack to secure the ladder to the top of ladder rack.  
         [0010]     Finally, an object of the present invention is to provide an improved ladder securement device for a ladder rack which is relatively simple and durable in construction and is safe, efficient, and effective in use.  
       SUMMARY OF THE INVENTION  
       [0011]     The present invention provides an improved ladder securement device for a ladder rack including at least one pivot mount adapted for mounting on a ladder rack and a generally horizontal pivot bar pivotably mounted on the at least one pivot mount rotatable about an axis generally defined by a center longitudinal axis of the pivot bar. At least two generally inverted L-shaped ladder-engaging hooks are mounted on the pivot bar adjacent opposite ends thereof, the ladder-engaging hooks pivotable between a ladder engaging position and a ladder release position and a handle is connected to the pivot bar for rotating the pivot bar about the center longitudinal axis thereof. Finally, the ladder-engaging hooks are adapted to extend over and engage a side rail of at least one ladder mounted on the ladder rack when the ladder-engaging hooks are in the ladder engaging position.  
         [0012]     The present invention as thus described provides a substantial improvement over those devices found in the prior art operative for securing ladders on ladder racks. For example, because the ladder-engaging hooks of the present invention engage the side rails of the ladder to enclose the side rail generally on four sides thereof in combination with the ladder rack, the chances of the ladder slipping from the ladder rack and falling to the ground accidentally are virtually eliminated, barring catastrophic failure of the ladder rack structure and/or ladder securement device of the present invention. Also, because the ladder is secured on the ladder rack merely by rotating the hooks into the ladder securement position via the handle which is located below the ladder supporting frame of the ladder rack, it is unnecessary for the user of the present invention to climb up onto the ladder rack to secure the ladder thereon, thus greatly reducing the possibility of injury of the person securing the ladder on the ladder rack. Finally, because the ladder securement device of the present invention includes at least two spaced apart ladder-engaging hooks which are simultaneously pivoted to engage or disengage from the ladder, it is a far simpler procedure to secure a ladder on the ladder rack equipped with the present invention than in using those devices found in the prior art. It is thus seen that the ladder securement device of the present invention provides a substantial improvement over those devices found in the prior art.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a perspective view of the improved ladder securement device for a ladder rack of the present invention mounted on a vehicle;  
         [0014]      FIG. 2  is a detailed perspective view of the present invention; and  
         [0015]      FIG. 3  is a detailed end elevational view of the improved ladder securement device for a ladder rack of the present invention securing a ladder on a ladder rack.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]     The improved ladder securement device  10  of the present invention is shown best in  FIGS. 1-3  as being mounted on a ladder rack  70  which is mounted on a vehicle  90 , the ladder rack  70  including a plurality of upwardly-extending support struts  72   a ,  72   b ,  72   c  and  72   d  which support the ladder support frame  74  above the cab  92  and bed of the vehicle  90 . The ladder support frame  74  would preferably be generally rectangular in shape and would include a pair of longitudinally extending main frame beams  76   a  and  76   b  and at least two transversely extending ladder support beams  78   a  and  78   b  which extend between and connect the main frame beams  76   a  and  76   b , as shown best in  FIG. 1 . Finally, extending upwards from the main frame beams  76   a  and  76   b  are a plurality of ladder retention struts  80   a - d  which generally prevent the ladder  100  being supported on the ladder rack  70  from sliding off the side of the ladder rack  70 . Of course, there are numerous different types of ladder racks  70  which are adapted for mounting on vehicles  90 , but the above description of a standard ladder rack should be understood to apply generally to those other ladder racks found in current use, and some variation from the above description is expected and will not affect the functionality of the improved ladder securement device  10  of the present invention when used in connection with many different types of ladder racks  70 .  
         [0017]     The improved ladder securement device  10  of the present invention is shown best in  FIGS. 1-3  as including forward and rearward pivot brackets  12   a  and  12   b  each of which include a generally flat horizontal mounting plate  14 , a downwardly depending pivot support strut  16  and a pivot bar mounting cylinder bearing  18  adapted to rotatably support the pivot bar  20  therein. As shown best in  FIGS. 1 and 3 , the pivot mount brackets  12   a  and  12   b  would each be mounted to the underside of one of the main frame beams  76   a  with the pivot mount brackets  12   a  and  12   b  being spaced from one another approximately four to seven feet, depending on the size of the ladder rack  70  and the length of pivot bar  20 . It is expected that the pivot mount brackets  12   a  and  12   b  would be secured to the ladder rack  70  by bolt and nut combinations, screws or the like, although the exact means by which the pivot mount brackets  12   a  and  12   b  are secured to the main frame beam  76   a  is not critical to the present invention.  
         [0018]     As shown best in  FIGS. 2 and 3 , the pivot bar  20  is preferably a longitudinally extended generally cylindrical metal bar which may be either solid or may be constructed as a hollow pipe, depending on the construction materials used and weight considerations taken into account in connection with the use of the present invention. It is further preferred that the pivot bar  20  have a length of approximately four to eight feet and have an outer diameter of approximately one inch, with the pivot bar  20  being rotatably mounted within the pivot bar mounting cylinder bearings  18  of pivot mount brackets  12   a  and  12   b . Due to the length of pivot bar  20 , it may be preferable to include a joint  22  which permits the pivot bar  20  to be separated into two sections, which also provides for simpler installation and replacement of the pivot bar  20  should such become necessary during use of the improved ladder securement device  10  of the present invention. In the preferred embodiment, this joint  22  would be of any standard kind of bar joint, such as the retractable pin and pin-receiving hole type of joint shown best in  FIG. 2  in which the smaller diameter section of one-half of the pivot bar  20  is slid into the other half of pivot bar  20  and secured therein as the pin pops out of and extends through the hole shown in the second half of pivot bar  20 . Of course, many different types of joints  22  may be used in connection with the pivot bar  20  of the present invention, and such substitution would be understood by those skilled in the art of metal fabrication.  
         [0019]     Mounted on and extending upwards and inwards from opposite ends of pivot bar  20  are a pair of ladder-engaging hooks  24   a  and  24   b , as shown best in  FIGS. 2 and 3 . As each of the ladder-engaging hooks  24   a  and  24   b  are generally identical, the following description of ladder-engaging hook  24   a  should be understood to apply equally to ladder-engaging hook  24   b . Mounted on and extending upwards and inwards from pivot bar  20  is lower hook strut  26  which, in the preferred embodiment, would be a generally flat metal bar having a first section  28  which connects to the pivot bar  20  at the base thereof and an upper section  30  which extends at approximately a forty-five degree angle from the lower section  28  of lower hook strut  26  such that, when lower section  28  of lower hook strut  26  extends upwards and inwards from pivot bar  20 , upper section  30  of lower hook strut  26  is generally upright, as shown in  FIG. 3 . Mounted on and extending upwards from upper section  30  of lower hook strut  26  is a generally inverted L-shaped upper ladder-engaging bar  32  which includes a first leg which extends upwards from upper section  30  of lower hook strut  26  and a second leg  36  which extends generally perpendicular to first leg  34  outwards therefrom. In the preferred embodiment, the upper ladder-engaging bar  32  would be a generally flat metal bar having a height of approximately four to eight inches on first leg  34  and having a width along second leg  36  of approximately two to six inches, depending on the ladder  100  to be retained on the ladder rack  70  and other functional features which will be determined through experimentation with the present invention.  
         [0020]     Mounted on the forward end of pivot bar  20  and extending downwards therefrom is a handle  40  which, in the preferred embodiment, would have a length of approximately two to three feet and is operative to rotate the pivot bar  20  within the pivot bar mounting cylinder bearings  18  of pivot mount brackets  12   a  and  12   b , as shown best in  FIG. 3 . The handle  40  would preferably also include a pivot stop  42  mounted on the upper end of the handle  40  which prevents overrotation of the pivot bar  20 , and it is further preferred that the handle  40  be detachable from the pivot bar  20  by including a handle joint  44  which would operate in a manner similar to the pivot bar joint  22  of pivot bar  20  to permit the handle  40  to be separated and removed from the remainder of the improved ladder securement device  10  of the present invention. Finally, a latch assembly  50  is preferably mounted on one of the upwardly extending struts  72   a  of ladder rack  70  to releasably secure the handle  40  in the position adjacent the upwardly extending strut  72   a , as shown best in  FIGS. 2 and 3 . Although the latch assembly  50  may be of any appropriate type which secures the handle  40  to the upwardly extending strut  72   a , it is preferred that the latch assembly  50  include a spring-biased pin  52  which releasably extends to secure the handle  40  within the latch assembly  50 , the latch assembly further including an outwardly extending tab section  54  which aligns with the pin-receiving tab  46  mounted on the lower end of handle  40  when the handle  40  is housed within latch assembly  50  to permit a lock  60  to extend through the pin-receiving tab  46  and forwardly extending tab  54  to lock the handle  40  in the position adjacent the upwardly extending strut  72   a , as shown in  FIG. 3 .  
         [0021]     The improved ladder securement device  10  of the present invention functions to secure a ladder  100  on a ladder rack  70  in the following manner. Initially, the handle  40  would be operated to rotate the pivot bar  20  and thus ladder-engaging hooks  24   a  and  24   b  to the ladder release position shown as a dotted line positioning of  FIG. 3 . Overrotation of the pivot bar  20  is prevented from happening by the pivot stop  42  mounted on handle  40  and, further, because of the weight balance of ladder-engaging hooks  24   a  and  24   b  versus handle  40 , the pivot bar  20  preferably will remain rotated in its ladder release position until the handle  40  is physically pivoted downwards by an operator of the present invention. The ladder  100  would then be placed on top of the ladder rack  70  with the ladder extending over the ladder support beams  78   a  and  78   b  generally adjacent main frame beam  76   a  and hence generally adjacent ladder retention struts  80   a  and  80   b . Specifically, it is the side rails  102   a  and  102   b  of the ladder  100  which are generally adjacent the ladder retention struts  80   a  and  80   b , as shown best in  FIGS. 1 and 3 , which is a critical feature for the proper operation of the present invention.  
         [0022]     Once the ladder  100  is positioned on ladder rack  70 , the handle  40  is pivoted downwards, thus pivoting the ladder-engaging hooks  24   a  and  24   b  mounted on pivot bar  20  upwards and outwards into their ladder-engaging position shown by the solid line position of  FIG. 3 . The upper ladder-engaging bar  32  of each of the ladder-engaging hooks  24   a  and  24   b  engages the side rails  102   a  and  102   b  of the ladder  100  and the second leg  36  of upper ladder-engaging bar  32  extends over the side rails  102   a  and  102   b , as shown in  FIG. 3 . The side rails  102   a  and  102   b  of ladder  100  are thus surrounded on all four sides of the side rails  102   a  and  102   b , specifically by the ladder support beam  78   a , ladder retention strut  80   a , and the first and second legs  34  and  36  of upper ladder-engaging bar  32  of ladder-engaging hook  24   a . It is thus virtually impossible for the ladder  100  to disengage and fall from the ladder rack  70 , and therefore transportation of the ladder  100  on ladder rack  70  is made far safer and easier than transport of ladders by those devices found in the prior art.  
         [0023]     Once the handle  40  has been pivoted downwards, it may be slid into latch assembly  50  by opening and then closing spring-biased pin  52 , thus releasably retaining the handle  40  within the latch assembly  50 . This, in turn, secures the ladder-engaging hooks  24   a  and  24   b  in their ladder-engaging position, as shown in  FIGS. 1 and 3 , thus securing the ladder  100  on the ladder rack  70 . By adding the lock  60 , accidental release of the handle  40  from latch assembly  50  is prevented, and the vehicle  90  may be safely driven without worrying if the ladder  100  will accidentally disengage from the ladder rack  70 . Once the vehicle  90  has reached the location at which the ladder  100  is to be removed from the ladder rack  70 , the lock  60  would be disengaged and the handle  40  would be swung outwards from latch assembly  50  to pivot the pivot bar  20  within pivot bar mounting cylinder bearings  18  of pivot mount brackets  12   a  and  12   b  to shift the ladder-engaging hooks  24   a  and  24   b  from their ladder-engaging position to the ladder release position. The ladder  100  may then be quickly and easily removed from the ladder rack  70  for use at the job site.  
         [0024]     One of the benefits of the improved ladder securement device  10  of the present invention is that it is quite easy to install a pair of the ladder-securement devices  10  on opposite sides of a single ladder rack  70  to secure ladders on each side of the ladder rack  70 , should such installation and use be desirable. Furthermore, one of the benefits of the present invention is that the ladder  100  need not be positioned precisely in a specific location on ladder rack  70  to permit the present invention to function correctly, as the ladder-engaging hooks  24   a  and  24   b , when being moved from the ladder-release position to the ladder-engaging position, will engage the ladder  100 , specifically side rails  102   a  and  102   b  of ladder  100 , and shift the ladder to a position generally adjacent the ladder retention struts  80   a  and  80   b , thus shifting the ladder  100  into the proper securement position on ladder rack  70  merely through operation of the improved ladder securement device  10  of the present invention. Also, because the improved ladder securement device  10  of the present invention engages the side rails  102   a  and  102   b  of ladder  100  to secure the ladder  100  on the ladder rack  70 , it is relatively unimportant as to which type of ladder is to be secured on the ladder rack  70  as each and every ladder will include side rails, but may not include the particular type of ladder rung necessary for connection and securement as dictated by many of the inventions found in the prior art. Finally, because the pivot bar  20  and handle  40  may be separated and removed from the improved ladder securement device  10  of the present invention, the entire unit may be quickly and easily removed from the ladder rack  70  leaving only the pivot mount brackets  12   a  and  12   b  mounted thereon should a user of the present invention wish to remove the device from the ladder rack  70 , a feature not generally found in those devices found in the prior art.  
         [0025]     It is to be understood that numerous additions, modifications, and substitutions may be made to the improved ladder securement device  10  of the present invention which fall within the intended broad scope of the appended claims. For example, the size, shape, and construction materials used in connection with the improved ladder securement device  10  are not critical to the present invention so long as the functional characteristics of the device are neither degraded nor destroyed. Furthermore, the specific size and shape of the ladder-engaging hooks  24   a  and  24   b  may be modified or changed to accommodate various types of ladders  100  which will be used in connection with the present invention, and such modifications of size and shape are understood to be a part of this disclosure. Finally, it should be clear that through minor modification of the pivot mount brackets  12   a  and  12   b  and other elements of the improved ladder securement device  10  of the present invention, the present invention may be used in connection with virtually any type of ladder rack  70  currently being used on vehicles, and such modifications would be understood by one skilled in the art of metal fabrication and equipment modification.  
         [0026]     There has therefore been shown and described an improved ladder securement device  10  which accomplishes at least all of its intended objectives.

Summary:
An improved ladder securement device for a ladder rack includes at least one pivot mount adapted for mounting on a ladder rack and a generally horizontal pivot bar pivotably mounted on the at least one pivot mount rotatable about an axis generally defined by a center longitudinal axis of the pivot bar. At least two generally inverted L-shaped ladder-engaging hooks are mounted on the pivot bar adjacent opposite ends thereof, the ladder-engaging hooks pivotable between a ladder engaging position and a ladder release position and a handle is connected to the pivot bar for rotating the pivot bar about the center longitudinal axis thereof. Finally, the ladder-engaging hooks are adapted to extend over and engage a side rail of at least one ladder mounted on the ladder rack when the ladder-engaging hooks are in the ladder engaging position.