Abstract:
A slide rail assembly for providing adjustable positions for fifth wheel hitches including a slide rail having feet extending downward from the underside of the slide rail, adjacent feet being separated by a detent for receiving a slide locking mechanism, each of the feet having a recesses located at the bottom inside corner of each foot, respecting the assembly. The slide rail also comprises teeth with gaps therebetween, where the gaps are vertically aligned with the recesses.

Description:
BACKGROUND 
     1. Field 
     The present invention relates generally to fifth wheel hitches for coupling trailers to tractor trucks, and, in particular, fifth wheel hitches having adjustable positions, and further, to slide rail assemblies for fifth wheel hitches. 
     2. Description of the Related Art 
     Fifth wheel hitches for towing a trailer behind a towing vehicle have long been known in the art. Examples of fifth wheel hitches include those disclosed in U.S. Pat. Nos. 4,721,323, 5,449,191, and 5,707,070. 
     Large over-the-road freight trailers are usually coupled to trucks by means of a fifth wheel assembly whereby the truck rear drive axles directly support a portion of the trailer load burden. Usually, the fifth wheel couple and support point is located along the length of the tractor between the rear drive wheels and the front steering wheels thereby distributing the front trailer load. It is desirable for the fifth wheel coupling to be adjustable in the longitudinal position with respect to the truck to aid in control over distribution of the load. 
     Typically, a fifth wheel hitch includes a support frame for mounting the hitch to the towing vehicle, such as, for example, to a tractor truck. This support frame includes a pair of base rails that are bolted to the bed and/or frame of the truck, side brackets that are releasably mounted to the base rails and a head support mounted to the side brackets. A head assembly is mounted to the head support by means of a trunnion arrangement allowing for pivotal fore-and-aft movement. The head assembly includes a jaw assembly specifically adapted to releasably engage and hold a kingpin of a trailer desired to be towed by the towing vehicle. 
     Fifth wheel hitches tend to be adjustable axially with respect to the tractor frame. One way of achieving this feature is attach slide rails to the support frame of the hitch and configure a pedestal, upon which the head assembly is pivotally mounted, to slidably engage the slide rails. The conventional design of these slide rails is nothing more than a flange extending inward of the slide assembly which may be angled metal. The rail is mounted to the support frame by fillet welding and by bolts. 
     However, the flange-type slide rail, since it is a single layer of material, provides only limited support to resist any upward loads. Further, the welding done to attach the rail to the support frame is time consuming, in addition to providing only a relatively weak attachment. Therefore, a need is identified for a slide to provide increased resistance to upward tending loads. A further need exists for such a slide rail to be manufactured in a reduced amount of time, but with greater strength of attachment to its support frame. 
     SUMMARY 
     The present disclosure is directed to a slide rail and a slide rail assembly that satisfies this need. 
     For purposes of summarizing the invention, certain aspects, advantages, and novel features of the invention have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any one particular embodiment of the invention. Thus, the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. 
     A slide rail according to the present invention comprises a plurality of feet extending downward from the slide rail&#39;s underside. Each of the feet define a recess located on the inside bottom corner such that the recess is open to both the inside surface and the bottom surface of foot. The slide rail also comprises teeth extending to the inside of the slide rail assembly. Between the teeth are gaps that are vertically aligned with the recesses. Each of the gaps have ridges disposed about rims of the gaps on the upper side of the slide rail. The slide rail is attached to a mounting plate by welding within the recesses where the slide rail feet meet the mounting plate. 
     A further embodiment includes an assembly comprising one or more slide rails as described above and mounted as described above. 
     These and other embodiments of the present invention will also become readily apparent to those skilled in the art from the following detailed description of the embodiments having reference to the attached figures, the invention not being limited to any particular embodiment(s) disclosed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears. 
         FIG. 1A  is an exemplary towing vehicle and trailer to depict general operation of an adjustable fifth wheel hitch assembly; 
         FIG. 1B  is a side view of an exemplary fifth wheel hitch assembly showing fore and aft adjustment of such assembly; 
         FIG. 1C  illustrates an exemplary hitch plate; 
         FIG. 1D  (PRIOR ART) is an exemplary support for a fifth wheel hitch assembly depicting, inter alia, stop blocks according to the prior art; 
         FIG. 2  is the top plan view of an exemplary fifth wheel assembly showing slide rail assemblies according to the present invention; 
         FIG. 3  is an isolated perspective view of a slide rail assembly according to an embodiment of the present invention; 
         FIG. 4  is an isolated perspective view of a prior art slide rail assembly depicting the prior art welding method used to form the weldments. 
     
    
    
     DETAILED DESCRIPTION 
     The various embodiments of the present invention and their advantages are best understood by referring to  FIGS. 1  through X of the drawings. The elements of the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention. Throughout the drawings, like numerals are used for like and corresponding parts of the various drawings. 
     An adjustable fifth wheel assembly  101  includes a fifth wheel hitch assembly  110  pivotally mounted on moveable pedestal  155 . Fifth wheel hitch assembly  110  comprises hitch plate  130  with slot  135  opening toward the aft end of fifth wheel assembly  101  for receiving a king pin  115  from trailer  119 . Fifth wheel hitch includes locking mechanism (not shown) to secure king pin within slot  135  for towing. Moveable pedestal  155  is configured with left and right slide flanges  111 ,  114  and slidably engaged thereby with slide assembly  120  which is mounted to tractor frame. Left and right slide assemblies  120   a, b  permit longitudinal positioning of fifth wheel hitch assembly  110  with respect to tractor frame. 
       FIG. 1D  depicts an example of the prior art slide rail where slide rail assembly  120   a  is comprised of left and right slide rail plates  102   a, b  tied in parallel by two or more tie bars  104   a, b  which form slide frame  121 . Left slide rail  102   a  is attached to the upper surface of left slide rail plate  102   a  and right slide rail  151   a  is attached to upper surface of right slide rail plate  102   b  such that fifth wheel hitch assembly  110  and pedestal  155  are located therebetween, inboard of the left and right slide rails  102   a, b . Slide rail plates  102   a, b  and slide rails  151   a, b  each have longitudinal axes which parallel the longitudinal axis of tractor  109 . Slide stop blocks  105   a–d  are located at each end of each slide rail plate  102   a, b . Slide stop blocks  105   a–d  prevent over travel of pedestal  155 . As is shown in the illustration, slide rails  151   a, b  of the prior art are typically a flange extending inboard of the assembly, slidably receiving flanges  111 ,  114  of pedestal  155 . 
     Referring now to  FIG. 2 , exemplary slide rail assemblies of the present invention are described where left and right slide rail assemblies  201   a, b  are shown installed on left and right slide plates  102   a, b . In this top view, slide rail  201   a, b  are shown to comprise a plurality of guide teeth  213  extending inboard of the slide frame  121 . Slide rails  201   a, b  may be cast as a single member, or may be comprised of a plurality of segments, each of said segments being cast steel. 
       FIG. 3  is a detailed view of a left or right slide rail or a slide rail segment  201  according to the present invention. Slide rail  201  comprises plurality of feet  310  disposed along a line parallel to slide rail&#39;s  201  longitudinal axis and extending downward from the underside of the slide rail  201 . The slide rail feet  310  are seated upon left slide rail plate  210  when the assembly is complete. Each of the feet  310  possess a cavity  312  located in a bottom corner of each of the feet  310  such that cavity  312  opens to both the inboard and bottom surfaces of each of the feet  310 . Between each of the feet  310  is detent space  309  for receiving a slide lock mechanism (not shown) mounted on the pedestal  155  which locks the fifth wheel assembly  130  at the desired longitudinal position relative to tractor. 
     Guide teeth  213  comprise the upper portion of left slide rail  201  and are disposed longitudinally along slide rail  201  and extend inboard relative to slide frame  121 . Guide teeth  213  are separated by gaps and are aligned vertically with detents  309  so that gaps are aligned vertically with feet  310  and cavities  312 . Guide teeth  213  provide downward retention of pedestal  155  on slide frame  121  via pedestal flanges  111 ,  114  and guide the pedestal  155  longitudinally throughout pedestal adjusting movement. Thus, guide teeth  213  take the place of a solid, linear guide lip. Each gap may also comprise a ridge  330  disposed along the rim of gap, preferably being at its highest point along the outward portion of gap, with respect to slide frame  121 , and tapering toward the inboard of the slide frame  121 . The added material disposed about the rim of gap provides support for guide tooth  313  to resist upward force that may be imparted by movement of pedestal  155 . 
     Left and right slide rails  201   a, b  are attached to left and right slide plates  102   a, b  by welding and by fasteners. Advantageously, slide rails  201   a, b  are welded to slide plates  102   a, b  at each cavity  312  such that material from cavity  312  is fused with material from slide plate  102 . A welding device (not shown) may include a robotic welder, well-known in the relevant arts, that is programmed to apply welds at pre-determined locations, for a pre-determined time and at a pre-determined angle. Thus, gap is vertically aligned with cavity  312  to provide access to a welding device to complete the weld procedure. Preferably, a welding device is allowed to “dwell” within cavity  312  for a period of about 3–5 seconds to allow more weld material to co-mingle and fuse. 
     This welding technique provides a number of advantages over earlier methods of welding slide rail  201   a, b  to slide plate  210 ,  212 . Because the welding device is allowed to dwell within the cavity, greater weld penetration is achieved, i.e. more material from the two pieces is fused, which yields a stronger weld. The size of the cavity allows for a larger weld which attaches a greater area of each piece. 
     At the same time, weld material does not form on the top surface of slide plate  102   a, b  in the area where left and right flanges  111 ,  114  of pedestal  155  would travel (the slide area). With the former well-known fillet weld technique an example of which is shown in  FIG. 4  (Prior art), weld material  401  forms in the slide area of slide plate  102 . This results in rough or inhibited travel of flanges  111 ,  114  through the slide area and prevents smooth adjustment of pedestal  155 . To mitigate against this requires the extra production step of manually grinding away such excess material to maintain a clear slide area, increasing production time and costs. 
     A further advantage of attaching slide rails with this welding method is that welding within cavity  312  is more accurate than fillet welding, especially when using a robotic welder. Cavity  312  provides a stable target for the welder and the welder is not required to move during application of the weld. As would be appreciated by those skilled in the art with the benefit of reading this disclosure, the use of cavity welding as herein described also results in a faster welding time and thus, further decreasing production time and cost. In addition, gaps allow welder to attack weld at a greater angle with respect to the slide plate  102  thus improving weld penetration. 
     It should be noted that slide rails  201  could be configured with a solid linear guide lip, see in  FIG. 1D , instead of guide teeth  313  and the weld method described above could still be employed. However, those skilled in the relevant arts will recognize that a linear guide lip configuration would required a welder to attack the weld at a shallower angle, therefore reducing the strength of the weld. Further, because of the added material about the rim of gap in slide rail  201  configured with guide teeth  313 , the downward support is greater than that exhibited by the linear lip configuration. 
     Slide rail  201  is also secured to slide plate  210 ,  212  by fasteners inserted through mounting apertures  305   a, b  &amp;  c  which align with corresponding apertures (not shown) through slide plate  102 . Mounting apertures  305  are preferably defined within slide rail  201  where mounting aperture  305  is bored into top of slide rail and through foot  310 . 
     Slide rail  201  can be a–d,  202   a–d  single cast piece or can be comprised of a plurality of slide rail segments. The number of slide rail segments that comprise slide rail  201  may vary depending upon design requirements. Similarly, slide rail segments may be of various lengths depending upon design requirements. During production, slide rail segments are not only affixed to slide plates  102  as described above, but also butt-welded to together where the respective abutting ends meet to form a stronger bond. For towing applications involving large tractor-trailer rigs, slide rail segment should be between about twelve (12) inches and about sixteen (16) inches. 
     As described above and shown in the associated drawings, the present invention comprises an apparatus for a fifth wheel slide rail and relate method of assembly. While particular embodiments of the invention have been described, it will be understood, however, that the invention is not limited thereto, since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. It is, therefore, contemplated by the appended claims to cover any such modifications that incorporate those features or those improvements that embody the spirit and scope of the present invention.