Abstract:
A ladder rack for work vehicles comprises a pair of side rails held in parallel, spaced relation by a pair of crossbars. Extending between the crossbars is at least one hook bar. The side rails, crossbars and hook bars comprise aluminum extrusions incorporating clamping ridges adapted to be engaged by clamps for rendering the structure rigid. No welding is required. A latch mechanism is affixed to a rearmost crossbar for releasably securing ladders on the rack. It comprises a crank on a rotatable shaft held by brackets affixed to the rear crossbar for rotation about an axis parallel to the crossbars. A rear hook is keyed to the shaft and aligned with a front hook affixed to the hook bar. The front and rear hooks can be made to engage spaced ladder rungs. An air spring connected between the rack frame and the rotatable shaft resists rotation of the rear hook member.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    I. Field of the Invention 
         [0002]    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 worksite, and more particularly to a roof rack with an improved clamp arrangement for securing such ladder loads onto the roof rack to prevent the loss of the ladder load during transport thereof. 
         [0003]    II. Discussion of the Prior Art 
         [0004]    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 worksite. Such cargo often includes extension ladders and/or stepladders. 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. 
         [0005]    Various other mechanisms have been devised for latching ladders onto a ladder rack and the below-listed patents represent illustrative efforts of other inventors to secure ladders in place. 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Falastich 
                 4,170,331 
               
               
                   
                 Nutt 
                 4,262,834 
               
               
                   
                 Weger, Jr. 
                 4,618,083 
               
               
                   
                 Nutt 
                 4,813,585 
               
               
                   
                 Sutton et al. 
                 5,186,588 
               
               
                   
                 Finley 
                 5,242,094 
               
               
                   
                 McLellan 
                 5,603,591 
               
               
                   
                 Pyler 
                 6,290,113 
               
               
                   
                   
               
             
          
         
       
     
         [0006]    For the most part, these prior art ladder rack assemblies are of a welded configuration having longitudinally extending side rails attached to transversely extending crossbar members by a welded connection, which limits the ability for a given design to be used on different van vehicle models because of the inability to adjust the welded configuration. In most prior art ladder racks, a pair of longitudinally extending side rails are held in parallel, spaced-apart relation by crossbar members extending therebetween and welded to the side rails. 
         [0007]    In contrast to what is described in the above-cited prior art, the roof rack and associated ladder clamping device of the present invention is fabricated from lightweight aluminum extrusions without the need for any welds. As such, racks can be packaged and shipped in a relatively small carton and assembled by the user using a single tool, namely, a socket wrench with a one-half inch socket. Because of the design of the extrusions employed for the side rails and crossbar members of the roof rack, even though the assembled rack is light in weight, it remains very rigid and able to support heavy loads without bending. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention is directed to a ladder clamping assembly for a vehicle roof rack where the roof rack includes a pair of spaced-apart, longitudinally extending side rails held in parallel relationship by a plurality of transversely extending crossbars that are clamped to the pair of side rails at opposed ends of the crossbars. Both the side rails and the crossbars comprise metal extrusions having clamping ridges extending along the length dimension thereof. 
         [0009]    The ladder rack may include one or more ladder clamping assemblies. The ladder clamping assembly itself comprises an elongated hook bar that extends between and is clamped to the clamping ridges of adjacent ones of the plurality of crossbars. The hook bar supports a front hook member that is longitudinally positionable along the length dimension of the hook bar and is adapted to engage an upper ladder rung of a ladder when being carried on the vehicle roof rack to prevent forward movement of a ladder. 
         [0010]    The ladder clamping assembly further comprises first and second bearing brackets that support a cylindrical rod and where the first and second bearing brackets are clamped to the clamping ridges of a common one of the plurality of crossbar members for journaling the cylindrical rod for rotation about an axis that is parallel to the crossbar members. A rear hook member is keyed to and clamped on the cylindrical rod at a location that is aligned with the hook bar and a crank arm is clamped to the cylindrical rod whereby manual rotation of the crank arm is adapted to bring the rear hook member into engagement with a lower ladder rung to prevent rearward movement of a ladder when being carried by the roof rack. 
         [0011]    Further 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. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a perspective view of a roof rack incorporating a ladder clamping assembly in accordance with the present invention; 
           [0013]      FIG. 2  is an enlarged detailed drawing showing the manner in which a crossbar of the roof rack attaches to its side rail; 
           [0014]      FIG. 3  is an end view of the extrusion comprising the hook bar; 
           [0015]      FIG. 4  is an exploded detailed view illustrating the assembly of the hook bar to a crossbar of the roof rack and the attachment of a front horn tube to a side rail; 
           [0016]      FIG. 5  is a perspective view of a rear clamp assembly; 
           [0017]      FIG. 6  is an exploded view illustrating how the rear clamp assembly attaches to a rear crossbar; and 
           [0018]      FIG. 7  is a detailed view showing the rear clamp assembly assembled to the rear crossbar of the roof rack. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0019]    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. 
         [0020]    Referring first to  FIG. 1 , a vehicle roof rack with ladder clamping devices of the present invention incorporated is indicated generally by numeral  10 . It is seen to comprise a pair of tubular side rails  12  and  14  of extruded aluminum that are held in parallel, spaced-apart relationship to one another by a plurality of crossbars  16  and  18 . The manner in which the crossbars attach to the side rails will be discussed later with the aid of  FIG. 2 , but for now, it is suffice to say that these parts are clamped to one another rather than being welded as in most prior art roof racks. Extending along the length dimension of the tubular side rails  12  and  14  is a clamping ridge  23  ( FIG. 2 ) formed by the extrusion die to resemble an inverted T. 
         [0021]      FIG. 2  shows the manner in which the rear crossbar  18  is clamped and held to the right side rail member  12 , taking advantage of clamping ridges formed on both the crossbar  18  and the side rail  12 . As a first step, an L-shaped support bracket  25  is clamped to a clamping ridge  23  of the extruded side rail  12  using a clamping plate  21  where the clamping plate  21  and support bracket  25  are held together by a screw and bolts  27  and  27 ′. The left end of the crossbar  18  is then made to rest on the L-bracket  25  and then bearing bracket  40  and wedge plate  31  are made to engage the clamping ridges  47  and  49  of the crossbar  18  shown best in  FIG. 6 . A shoulder bolt  33  is then inserted through the bearing bracket  40  and wedge plate  31  and a washer and ½″ aircraft nut  35  are screwed onto the bolt  33  and tightened to move the wedge plate to the right and thereby rigidly clamp the left end of the crossbar  18  to the side rail  12 . 
         [0022]    Attached to the front end of the side rails  12  and  14  are tubular horn members  37  and  39  comprising tubing that has been formed into an arcuate curve so as to extend upwardly and outwardly relative to the side rails to which they are attached. Without limitation, the horn members may lie in a plane that is about 30° to the vertical. Details of the attachment method can be seen in  FIG. 4  where a proximal end of the tubular horn  37  fits into a tubular clamp  41  that is designed to slip over the forward end of the side rail  12  and secured to the clamping ridge thereof upon tightening of the nuts  43 . 
         [0023]    With reference to  FIGS. 1 and 4 , extending between and clamped onto the crossbars  16  and  18  are hook bar extrusions  20  that supports front hook members  22  thereon. The front hook members each comprise a right angled bracket  24  having its base  26  affixed to the hook bar  20  so as to be adjustable therealong and when at a desired position is firmly held in place by snuggling down a pair of bolts  28  that fit into T-nuts  32  ( FIG. 4 ). 
         [0024]      FIG. 3  is an end view of the hook bar extrusions  20  and it can be seen that they incorporate a T-slot  30  in a top portion thereof into which T-nuts  32  are fitted, as shown in  FIG. 4 . It will be appreciated that when the bolts  28  are loose, the front hook member  22  can be slid longitudinally with the T-nuts riding in the T-slot  30 . When in a desired location that will engage a rung of a ladder to be transported, the bolts  28  are tightened to lock the front hook member  22  in place. The hook bar extrusions  20  also include clamping ridges  46  and  48  running the length thereof. 
         [0025]    While not visible in  FIG. 1 , the vertical leg of the right-angled bracket  24  has a longitudinal slot formed therein. Bolts (not shown) passing through the apertures  34  can ride up or down in that slot to allow adjustment the height of the hook  22  relative to the hook bar  20  and by tightening those bolts the selected height setting is maintained. 
         [0026]    Clamped to the rearmost crossbar  18  is a rear clamp assembly indicated generally by numeral  36 . Since they are identical in construction, only one assembly needs to be described. A perspective view of a rear clamp assembly detached from the roof rack is illustrated in  FIG. 5 . Shown in  FIG. 5  is the first bearing bracket  38  and a second bearing bracket  40  used to support a cylindrical rod  42 . The bearing bracket  38  is adapted to be clamped to the crossbar  18  as previously explained with the inwardly turned end portion  54  thereof engaging a clamping ridge  49  formed on the crossbar extrusion  18  as seen in  FIG. 6 . A further clamping ridge  47  becomes engaged by wedge plate  58  and when the nut  56  is tightened, the wedge plate is camed to the right, causing the bracket  38  to become rigidly secured to the crossbar  18 . The bearing bracket  40  is likewise secured to the crossbar  18  when the barb-like protuberance  44  engages the clamping ridge  49  and the nut  52  is tightened to move the wedge plate  50  into engagement with the clamping ridge  47  of the crossbar  18 . 
         [0027]    The cylindrical shaft  42  supports a rear hook member  60  thereon. More particularly, as seen in  FIG. 5 , the rear hook member  60  is secured to a leg  62  that is bolted to a cylindrical hub  63  through which the cylindrical shaft  42  is made to pass. While not visible in  FIG. 5 , projecting radially inward from the I.D. of the hub  63  is a key that is adapted to fit within a keyway  66  milled or otherwise formed in the surface of the cylindrical shaft  42 . Thus, the hub  63  and the attached rear hook member  60  can be positioned axially along the length of the shaft  42  allowing the rear hook member to be aligned with the front hook member along the length of the hook bar  20 . 
         [0028]    As further seen in  FIG. 5 , a gas spring  68  is operatively coupled between a rod clamping bracket  64  keyed to the shaft  42  and the bearing bracket  40 . More particularly, the gas spring  68  has its cylinder segment bolted by a bolt  70  to the free end of leg  29  of bearing bracket  38  and its piston rod is secured by a bolt  72  to an extension  74  of the rod clamping bracket  38 . The gas-filled spring consists of a precision rod attached to a piston moving within a sealed cylinder containing nitrogen at high pressure. Output forces are the result of the differential between the pressure in the cylinder and atmospheric pressure outside the cylinder acting on the cross section of the rod. As the piston rod is introduced into the cylinder (compression stroke), the internal pressure increases according to the volume of gas displaced by the rod. This increase in force is typically between 5% and 50%. In comparison to mechanical springs, gas springs are almost constant force. All gas springs contain a small amount of oil to lubricate the main seal and rod and provide end of stroke damping. Hence, the gas spring is preferably mounted with its rod inclined downward off horizontal. This allows the oil to reach the main seal, lubricating it and extending the life of the gas spring. 
         [0029]    In the present application, the gas spring functions to urge the rear hook member  60  into engagement with a ladder rung thereby capturing the ladder between the front hook member  22  and the rear hook member  60 . Manual rotation of the crank arm  80  in the clockwise direction when viewed in  FIG. 1  is required to overcome the force exerted by the gas spring when it is desired to release and remove a ladder from the roof rack. The amount of torque applied to the cylindrical rod  42  by manual actuation of the handle  82  must far exceed any force against the rear stop member  60  by the ladder load upon rapid acceleration of the work vehicle. 
         [0030]    The crank arm  80  is clamped to the left end of the cylindrical rod  42  ( FIG. 5 ). Formed through the crank arm is an aperture  84 . Clamped onto a clamping ridge  23  formed along the length dimension of the side rail  12  is a lock bracket  86  ( FIG. 6 ) that also has an aperture extending through its thickness dimension. When the rear hook member  60  is in its raised, ladder rung-engaging disposition, the aperture  84  in the handle  80  becomes aligned with the aperture in the lock plate  86 . This allows the shackle of a padlock (not shown) to be passed through the aligned apertures and thereby lock the assembly, preventing removal of a stowed ladder. 
         [0031]    From what has been described, those skilled in the art will appreciate that the present invention provides an improved mechanism for releasably securing ladders to a roof rack of a work vehicle that will safely hold such ladders in place during transit, but allowing the ladders to be quickly disengaged for removal and reloading from and to a roof rack when at the worksite. Turning of the crank in a counterclockwise direction functions to overcome the force of the gas spring and rotation of the rear hook member from its ladder rung-engaging state to a position where the rear hook member is generally horizontal and out of the way of the ladder rungs, allowing the operator, while standing on the ground, to lift the ladder over the horizontal portion of the adjacent side rail and have the lower end of the ladder reach the ground while the upper end of the ladder remains resting against the curved horn member. The operator may then reposition himself or herself and grasp the ladder at its balance point and carry it to the location where it is to be used. 
         [0032]    In reloading a ladder onto the rack, it is carried in a generally vertical orientation alongside the vehicle and one side of the ladder is brought to rest against the curved and outwardly angled horn. The operator then lifts the rear end of the ladder and swings it over the adjacent side rail such that the ladder is now lying flat on the roof rack and is pushed forward until a leading rung proximate the top end of the ladder is brought into contact with the front hook member  22 . Next, the crank handle  82  is rotated in a counterclockwise direction when viewed as in the accompanying drawings to thereby elevate the rear hook member and bring it into engagement with a different ladder rung such that the ladder is effectively trapped between the front and rear hook members. It can be locked for security purposes by using a padlock securing the handle  84  to the lock bracket  86  as previously described. Even without such a padlock arrangement, the gas spring  68  affords sufficient resistance against clockwise rotation of the rear hook member due to sudden acceleration of the vehicle, thereby preventing shifting of the ladder load. 
         [0033]    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.