Abstract:
An ergonomically improved vehicle ladder rack has the top of its side rail(s) flush with the top surface of the rear cross-bar so that a foot portion of a ladder being transported may be made to slide off from the rack without a need for lifting it. To prevent lateral shifting of the ladder during transport on the vehicle, an abutment finger is added to the rotatable rung clamping assembly. The abutment finger blocks lateral shifting of a ladder when the rung hook is engaging a ladder rung and is non-blocking when the rung is disengaged.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     None 
     STATEMENT OF GOVERNMENT SPONSORSHIP 
     None 
     BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     This invention relates generally to roof or ladder racks mountable on the roof of motor vehicles for transporting one or more extension ladders and/or step ladders to a work site, and more particularly to the ergonomic construction that alleviates the need for a worker to lift the ladder vertically when removing a ladder from the roof rack upon reaching a work site. 
     II. Discussion of the Prior Art 
     Work vehicles, such as commercial vans, often incorporate a roof rack adapted to support cargo of one type or another to be used at a work site. Such cargo often includes extension ladders and/or step ladders. To avoid loss of the cargo during transport and possible serious injuries to other motorists who may be traveling behind the work vehicle, various means have been devised for securing cargo and especially ladders, to the ladder rack. For example, some have used bungee cords and ropes to tie ladders in place on the vehicle-mounted roof rack, but this is generally a considerable effort, especially given the height and placement of the ladder rack on the van roof. In applicant&#39;s printed application US 2011/0214944 A1, which is hereby incorporated by reference herein, there is described a ladder rack and especially an improved clamping structure for releasably securing ladders to a roof mounted ladder rack. It comprises a pair of side rails  12  and  14  that are held in parallel spaced-apart relation by front and rear cross-bars  16  and  18 . In that design, the side rails  12  and  14  are mounted so as to be upwardly offset from the top surface of the cross-bars  16  and  18 . 
     A clamp member  60  is affixed to a shaft  42  that is journaled for rotation about an axis parallel to the rear cross-bar  18 . The clamp member in the form of an L-shaped hook can be raised and lowered by manipulating a crank  82 . When the clamp member  60  is in its raised position, such as shown in  FIG. 1  of the aforereferenced published application, it is made to engage a ladder rung capturing the ladder between a fixed, front clamp member  22  and the rotatable clamp member  60 . Because the side rails  12  and  14  are elevated with respect to the ladder-supporting cross-bars  16  and  18 , a worker, standing on the ground, must reach up and lift the foot portion of the ladder over the adjacent side rail which has proven to be an arduous task for some workers, especially persons of smaller stature. The present invention obviates this problem by requiring less effort in order to transfer a ladder from its transport position atop the cross bars of the roof rack on the vehicle to a removed position. In the removed position the foot of the ladder is brought down to rest on the ground while the upper portion of the ladder remains in contact with the side rail  12  or  14  and its horn  37  or  39 . 
     While, after-the-fact, the present invention may appear simple, it solves a practical problem of allowing a worker to more readily remove or replace ladders from and onto a van mounted roof rack without strain. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention there is provided a pair of side rails that are held in parallel, spaced-apart relation by front and rear cross-bars. In the present invention, however, rather than having the side rails at a higher elevation than the front and rear cross-bars, the top surface of the cross-bars are made even or flush with the top surface of the side rails so that a ladder can readily be slid off the roof rack without a need to elevate the ladder to clear the side rail. 
     To prevent lateral shifting of a ladder during transport, there is added to the shaft of the rotatable clamping member an abutment finger that also rotates with the clamping members shaft so as to block lateral movement of a ladder when the clamping member is engaging a ladder rung but which moves to a non-obstructing position when the ladder clamping member is moved to its release position. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of a preferred embodiment, especially when considered in conjunction of the accompanying drawings in which like numerals in the several views refer to corresponding parts. 
         FIG. 1  is a partial perspective view of the preferred embodiment of the present invention; 
         FIG. 2  is a detailed, close-up view showing the rotatable clamping structure and the junction between the rear cross-bar and a rear-end of a side rail when the clamping member is in its non-rung engaging position; 
         FIG. 3  is a view like that of  FIG. 1  but with the ladder rung engaging clamp member in its elevated position; and 
         FIG. 4  is a view like that of  FIG. 2  but with the clamping member in its elevated, rung-engaging disposition. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     This description of the preferred embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. In the description, relative terms such as “lower”, “upper”, “horizontal”, “vertical”, “above”, “below”, “up”, “down”, “top” and “bottom” as well as derivatives thereof (e.g., “horizontally”, “downwardly”, “upwardly”, etc.) should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms such as “connected”, “connecting”, “attached”, “attaching”, “join” and “joining” are used interchangeably and refer to one structure or surface being secured to another structure or surface or integrally fabricated in one piece, unless expressively described otherwise. 
     Referring first to  FIG. 1 , a vehicle roof rack constructed in accordance with the present invention is indicated generally by numeral  10 . It is seen to comprise at least one, and preferably two, tubular side rails, as at  12  and  14 , of extruded aluminum that are held in parallel, spaced-apart relationship to one another by a front cross-bar  16  and a rear cross-bar  18 . Brackets, as at  20  and  22 , are attached to T-shaped clamping ridges (not shown) formed on the undersurface of the side rails  12  and  14 . The cross-bars  16  and  18  connect to the brackets  20  and  22  such that the top-surface  24  of the cross-bar  18  is even or flush with the arcuate top surface of the side rails  12  and  14 . 
     As in applicant&#39;s earlier invention of the afore-referenced published application 2011/0214944 A1, affixed to the rear cross-bar  18  is a rear rising clamp assembly indicated generally by numeral  26 . First and second bearing brackets  28  and  30  are used to journal a cylindrical rod  32  for rotation. The bearing brackets  28  and  30  are shown clamped to the rear cross-bar  18  such that the shaft  32  is rotatable about an axis that extends parallel to the rear cross bar  18 . 
     Affixed to the shaft  32  is a clamp member in the form of an L-shaped hook  34  that is adapted to engage a rung of a ladder when rotated to a generally vertical position as shown in  FIGS. 3 and 4 . When the clamp  34  is in its lower disposition as shown in  FIGS. 1 and 2 , it does not engage a ladder rung, allowing the foot of the ladder to be shifted laterally along the top surface  24  of the rear cross-bar and to pass over the junction between the rear cross-bar member  18  and the side rail  12  without the need to lift the ladder as was the case with the embodiment described in the afore-referenced published application 2011/0214944. 
     To prevent lateral shifting of a ladder during transport when the rotatable clamp  26  has the hook  34  in its raised disposition, there is provided an abutment finger  36  that is affixed to the shaft  32  by a ring  38  that is riveted or otherwise affixed to the shaft  32 . As can be seen in  FIGS. 3 and 4 , when the hook  34  is in its raised disposition so as to engage the rung of a ladder, the abutment finger  36  is also elevated so as to engage a ladders side rail to prevent lateral shifting of the ladder. However, when the clamping assembly is in its lowered disposition, out of engagement with a ladder rung, the abutment finger  36  is recessed with respect to the upper surfaces of the side rail  12  and the cross-bar  18  thereby allowing a worker to slide the ladder&#39;s foot portion from the rear cross-bar  18  without needing to lift it. 
     As in applicant&#39;s earlier invention of the &#39;494 application, a crank arm  40  is provided to facilitate rotation of the shaft  32 . It has been found convenient to install a generally flat shield plate  42  that extends over the rear-end of the side rail  12  so as to be in covering relation with respect to the joint or connection between the handle  40  and its coupling to the end of the shaft  32 . A spring latch  44  is affixed to the side rail  12  to capture the crank arm  40  when the rung clamping hook  34  is in its elevated disposition, such as when ladders on the roof rack are being transported to a work location. 
     When a worker arrives at a work site and wishes to remove an extension ladder from the vehicle&#39;s roof rack, he or she will depress the trigger on the spring latch  44  to open its jaws and release the crank arm  40 , By rotating the crank arm counterclockwise as viewed in  FIG. 1 , the clamp hook  34  will be moved from its vertical disposition, such as in  FIG. 4 , to the more horizontal disposition shown in  FIG. 1 . At the same time, the abutment finger  36  also rotates to a lowered disposition so that it does not interfere with the ability to slide the foot of the ladder so that its previously innermost ladder side rail no longer rests on the rear cross-bar&#39;s top surface  24 . The worker then lowers the ladder&#39;s foot onto the ground, keeping the upper portion of the ladder still engaged by the horn affixed to the front end of the side rail  12 . When the ladder is so positioned, the worker can readily move to the ladder&#39;s balance point and lift the upper end of the ladder free of the curved horn and walk with the ladder to its point of use. In that the upper surface  24  of the rear cross-bar  18  is flush with the upper surface of the side rail  12 , the worker is not required to lift or elevate the ladder, but only need slide the ladder off from the rear cross-bar&#39;s top surface  24 . 
     This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices, and that various modifications, both as to the equipment and operating procedures, can be accomplished without departing from the scope of the invention itself.