Patent Application
20170232904
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I. Field of the Invention
This invention relates generally to an apparatus to facilitate the loading and unloading of ladders onto and from the roof of road vehicles and, more particularly, to an improvement over the prior art that reduces the height profile of such apparatus to thereby decreases wind resistance and allows entrance to certain work sights having height restrictions.
II. Discussion of the Prior Art
The closest prior art to the present invention are U.S. Pat. Nos. 5,297,912; 6,427,889 and 6,764,268 to Avraham Y. Levi. Each comprise front and rear 4-bar linkages. In each, a first stationary bar is adapted for attachment to the vehicle's roof and a second movable bar is pivotally joined to the stationary bar by a pair of linkages. An elongated shaft is journaled for rotation in the stationary bars of the front and rear 4-bar linkages and one of the pair of linkages is clamped to the shaft whereby rotation of the shaft results in the rotation of the movable bar on which the ladder(s) being transported are disposed from their position atop the vehicle to a position straddling the side of the vehicle where it is within reach of a workman on the ground.
In each of these prior art designs, the movable bar rests atop the stationary bar when the load is located on the vehicle's roof. This stacked relation of the stationary and movable bars necessarily adds to the overall height of the ladder load while being transported. The height above the vehicle's roof not only results in greater wind resistance and noise at higher speeds of the vehicle, but there are also job sites, like parking garages, that have height restrictions that may be violated.
It is therefore a principle object of the present invention to modify the ladder racks of the prior art so as to reduce the overall height of the ladder rack mechanism by over 50%.
The instant invention comprises a ladder rack for a motor vehicle. It comprises a front and a rear 4-bar linkage assembly. Each includes a stationary bar member adapted to be attached to the roof of a motor vehicle so as to extend transverse to the longitudinal axis of the motor vehicle. A movable bar member comprising a ladder support is pivotally coupled and offset from the stationary bar member by a pair of rigid links arranged such that rotation of one of the pair of rigid links on each of the front and rear 4-bar linkage assemblies results in the movable bar members of the front and rear 4-bar linkage assemblies moving between a first disposition in which a top surface of the movable bar member is in coplanar relation with a top surface of the stationary bar member to a second disposition aligned and spaced from one side of the vehicle. A connecting rod extends longitudinally between the two 4-bar linkage assemblies, the connecting rod being journaled for rotation in the stationary member of each. One of the pair of rigid links in each of the 4-bar linkage assemblies is coupled to the connecting rod whereby rotation of the connecting rod results in the movable bar members rotating between a position on the roof of the vehicle to a position along and parallel to one side of the vehicle.
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 with the accompanying drawings in which like numerals and the several views refer to corresponding parts.
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.
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The present invention achieves its advantage over the prior art in the way that the linkage members 24 and 26 are positioned relative to the stationary bar members 16, 18 and the manner in which the linkage 26 joins the movable bar member to the connecting rod 28. Referring to
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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.
