Abstract:
There is provided an apparatus for storing a ladder on the outer rear wall of a cab of a semi tractor. It comprises an outer stationary frame that is bolted to the rear surface of the tractor cab proximate one side of the cab and contained within the outer frame are first and second panels that are pivotally joined to one another where one of the first and second panels is also pivotally joined to the stationary frame. The second inner panel carries a ladder support bracket. When stowed, a latch mechanism prevents the inner articulated frame panels from extending relative to the stationary outer frame. Upon unlatching, the two inner articulated panels can be rotated such that the ladder will be positioned to the side of the tractor cab and accessible to an individual standing on the ground.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    I. Field of the Invention 
         [0002]    This invention relates generally to apparatus for storing a step ladder or extension ladder on the cab of a semi tractor, and more particularly to a ladder holder that when actuated, it delivers a stored ladder to a location accessible to a person standing on the ground alongside of the semi tractor. 
         [0003]    II. Discussion of the Prior Art 
         [0004]    Semi tractor and trailers carry lighting that periodically needs servicing. When it is considered that the overall height of a semi tractor and trailer is approximately 13 ft. 6 in. so as to comply with interstate highway bridge standards, it becomes necessary for the operator to have a ladder available in order to be able to reach lights atop the cab or trailer. 
         [0005]    The fuel efficiency of semi-trucks is influenced tremendously by aerodynamics. Most of the power generated by a semi tractor is utilized to overcome drag forces while operating at highway speeds. Aerodynamic fairings have therefore become standard equipment on modern tractors. 
         [0006]    The gap between the tractor cab and its trailer is a high drag region that is typically streamlined by providing tractor side panels as fairings that attach at the rear end of the cab along the sides thereof. Such side panels help prevent the air from entering the area between the cab and semi-trailer, thus substantially reducing the drag coefficient. It has been found that providing tractor side panels can yield a fuel saving of 0.7% for an articulated vehicle. 
         [0007]    These tractor side panels must not interfere with the semi-trailer turning. To minimize the gap, rubber strips can be fitted onto the trailing edges of the tractor side panels, thus extending them and reducing the gap to the maximum extent while still not interfering with the turning ratio of the trailer. 
         [0008]      FIG. 1  is a rear view of a semi tractor cab showing side panels  1  and  2  on the rear driver&#39;s side and rear passenger&#39;s side of the cab  3 . Also shown is a prior art ladder holder being used to support an extension ladder  4  against the rear surface of the cab  3 . 
         [0009]    It should be apparent from this view that in order for a person to access the ladder, that person must climb up upon the tractor&#39;s platform  5  ( FIG. 2 ) to which the vehicle&#39;s two rear drive axles are journaled at a location just forward of its fifth wheel coupler  6 . This area is often slippery due to accumulated grease and road dust, creating a hazard for the person seeking to remove or replace a ladder onto the rack on which it is normally stowed. 
         [0010]    It would therefore be advantageous to have a ladder holder attachable to the rear surface of a semi tractor cab and that will make the ladder readily accessible to a person standing on the ground alongside the cab, thereby obviating the need to climb up onto the tractor platform  5  in order to gain access to the ladder. The present invention provides such a ladder holder. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention provides a ladder mount for a semi truck that comprises an outer rectangular frame adapted for attachment to a rear surface of a tractor cab and having an articulated inner frame comprising a first frame panel pivotally hinged to the outer rectangular frame along a first vertical axis and a second frame panel pivotally hinged to the first frame panel along a second vertical axis where the second frame panel incorporates a support bracket adapted to engage a rung of an extension ladder or a step ladder. The outer rectangular frame is fastened to the rear surface of the tractor cab at a location such that when the inner articulated frame is unlatched with respect to the outer rectangular frame and the panels comprising the inner frame are pivoted about the first and second vertical axes, the second frame panel carrying the ladder will extend laterally out beyond the rear edge of the truck&#39;s side fairings. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0012]    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 in the several views refer to corresponding parts. 
           [0013]      FIG. 1  is a rear view of a semi tractor cab showing a prior art ladder mounting arrangement thereon; 
           [0014]      FIG. 2  is a side elevation view of a typical semi tractor incorporating side fairings; 
           [0015]      FIG. 3  is a rear view of a ladder holder constructed in accordance with the present invention; 
           [0016]      FIG. 4  is a perspective view of the ladder holder of  FIG. 3  on which an extension ladder is mounted; 
           [0017]      FIG. 5  is a perspective view illustrating the ladder holder of the present invention in a partially deployed configuration; 
           [0018]      FIG. 6  is a perspective view showing the ladder holder of the present invention in its fully deployed configuration; and 
           [0019]      FIG. 7  is a detailed drawing showing the latch mechanism used with the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0020]    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. 
         [0021]    Referring first to  FIG. 3 , there is shown a rear view of the ladder holder of the present invention. It is indicated generally by numeral  10  and is seen to comprise an outer rectangular frame  12  having a welded construction of a bottom frame member  14 , a top frame member  16  and left and right side members  18 ,  20 , defining a generally rectangular opening. The frame members  14 ,  16  and  18  may comprise rectangular metal tubes, preferably made of aluminum while the right frame member  20  comprises a tube of circular cross-section. 
         [0022]    Without limitation, the top and bottom frame members  14 ,  16  may be approximately 24-30 in. in length while the side frame members  18 ,  20  may be approximately 30-36 in. in length. 
         [0023]    Fitted within the rectangular opening of the outer rectangular frame member  12  and pivotally hinged thereto is an articulated inner frame assembly  21  having a first frame panel  22  which, in  FIG. 3 , is shown as being nested within a second frame panel  24 . 
         [0024]    The first frame panel  22  is seen to comprise a welded configuration having parallel, spaced-apart upper and lower horizontal frame members  26 ,  28  with perpendicular extending side frame members  30  and  32 . Again, the first frame panel  22  may incorporate extruded aluminum tubes of rectangular cross-section and a length of the frame members  26 ,  28  may typically be about 18-24 in. The numbers  30 ,  32  may have a length of about 27-30 in. 
         [0025]    As can be seen in  FIG. 3 , the upper frame member  26  of the first articulated inner panel  22  is pivotally hinged by bolts  34 ,  36  to the outer rectangular frame  12  and more particularly to the bottom frame member  14  thereby and the top frame member  16  thereof. 
         [0026]    In the view of  FIG. 3 , the first frame panel  22  is shown as being nested within the confines of the second frame panel  24 . The second inner articulated frame panel  24  comprises a welded assembly of upper and lower angle bars  38 ,  40  and left and right side panel  42  and  44 , respectively. The angle bars comprising the second articulated frame member  24  are sized such that the frame members  26 ,  28 ,  30  and  32  of the first articulated frame panel  22  fit within the confines of the second frame panel  24 . 
         [0027]    Also seen in  FIG. 3  and identified by reference numerals  46  and  48  are hinge pins that join the second frame panel  24  to the first frame panel  22 . 
         [0028]    Welded or otherwise attached to the second frame panel  24  are U-shaped brackets  50  and  52  that are adapted to straddle the right side frame member  20  of circular cross-section of the outer rectangular frame  12  when the first and second inner articulated frame panels are nested with respect to one another and releasably latched by a latch device  54  that is operatively disposed between the left side frame member  18  of the outer rectangular frame  12  and the left angle bar of frame member  42  of the second inner articulated frame panel  24 . 
         [0029]    Not visible in the view of  FIG. 3 , but seen in the view of  FIG. 5 , are a pair of generally L-shaped ladder support brackets  56  that are bolted or otherwise affixed to the upper angle bar frame member  38  of the second frame panel  24 . A ladder  58  is shown having its rung  60  supported by the L-shaped brackets  56 . 
         [0030]    Turning next to  FIG. 4 , it should be imagined that the bottom and top frame members  14  and  16  of the outer rectangular frame  12  are bolted to the back surface of the cab  3  just laterally inward from the side fairing  2  in the view of  FIG. 1 . 
         [0031]    Referring again to  FIG. 5 , here it is shown that the ladder  58  is supported by L-shaped brackets  56  secured to the second frame panel  24  which are now shown as being unlatched from the outer rectangular frame  12  such that the U-shaped brackets  50  and  52  are no longer engaging the right side frame member  20  of circular cross-section of the outer rectangular frame. The ladder is being swung away from its fixed mounting position as the first frame panel  22  is made to pivot about hinge pins  34  and  36  ( FIG. 3 ) while the second frame panel  24  pivots about its hinge pins  46  and  48 . 
         [0032]      FIG. 6  illustrates the ladder  58  in its fully deployed position ready to be lifted free of the brackets  56  by a person standing on the ground. Again, it is to be recognized that the outer frame  12  remains bolted to the rear surface of the vehicle cab and that the first frame panel  22  spans the width dimension of the vehicle&#39;s side fairing  2  and with the second frame panel  24  extending laterally and generally perpendicularly from the side fairing and therefore fully accessible by a person standing on the ground who now need only lift the ladder from the brackets  56  and move it to a desired work location. 
         [0033]    It will be appreciated that returning the ladder to its stowed disposition merely involves again placing a rung of the ladder on the brackets  56  while the articulated mount is in the disposition shown in  FIG. 6  and then swinging the first and second panels  22  and  24  in a clockwise direction when view in  FIG. 6  until the first frame panel  22  becomes nested within the second frame panel  24  and the two articulated panels are disposed within the opening defined by the members  14 ,  16 ,  18 ,  20  comprising the outer frame  12 . As the assembly is being closed, the user will insure that the U-shaped brackets  50  and  52  again engage the right circular frame member  20  and when the panels are fully nested, the latch  54  will operate to hold the ladder mount in its closed disposition with the ladder  58  closely abutting the rear panel of the truck cab. A bungee cord may be used to strap a lower ladder ring to the bottom frame member  14 . 
         [0034]    Those skilled in the art will appreciate that various latch mechanisms can be employed. The one illustrated in  FIG. 7  is especially designed as a low-cost latch mechanism fabricated entirely from extruded aluminum so that the members thereof may simply be cut from a length of an extrusion. It is seen to comprise a stationary latch plate  59  that in use becomes affixed to the second frame panel  24  proximate a lower end of a vertical one of the four angle bars  38 ,  40 ,  42  and  44 . The stationary plate  59  includes a shoulder  61 . The latch assembly further includes an extruded latch mounting plate  62  having a flat surface  64  that in use is affixed to a side frame member of the outer rectangular frame  12 . It also includes a horizontally extending, integrally formed arm  66  and a downwardly extending block  68  having a bore  70  formed therein for containing a spring  72 . 
         [0035]    Formed horizontally in the latch mounting plate  62  is an arcuate slot  74  for receiving therein a rounded hub  76  of the spring-loaded latch member  78 . The spring-loaded latch member  78  is also seen to include a shoulder  80  which is adapted to engage the shoulder  61  of the stationary latch plate  59 . Only when the spring-loaded latch member  78  is pushed downward when viewed in  FIG. 7  against the force of the spring  72  can the shoulder  80  clear the shoulder  61  to release the latch and allow the articulated inner panels to swing out in the manner previously described. 
         [0036]    When returning the inner articulated first and second panels to their nested position within the outer frame member  12 , the spring-loaded latch member&#39;s extension  82  will ride along the sloped cam surface  84  of the stationary plate  59  until the shoulder  80  snaps against the shoulder  61  under the influence of the coil spring  72 . This latch mechanism can readily be reached by a person standing on the ground and reaching his/her arm around the aerodynamic side fairing  2  seen in  FIG. 1 . 
         [0037]    It can be seen that the present invention provides a safe and effective mechanism for transporting and deploying a ladder carried on a rear surface of the cab of a semi tractor. 
         [0038]    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.