Abstract:
A stop block for preventing over travel of an adjustable fifth wheel hitch assemblies comprising a generally rectangular solid member having a double curve disposed in said member such that a long portion of said member is higher in elevation than a short portion of said member.

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 having stop blocks. 
     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. 
     Referring to  FIGS. 1A through 1D , a fifth wheel hitch assembly  101  includes a support frame  150  for mounting hitch assembly  101  to towing vehicle  109 , such as, for example, to a truck. Support frame includes a pair of base rails  102   a, b  that are bolted to the bed and/or frame of the truck  109 . Hitch plate  130  is mounted to a pedestal  155  by means of a trunnion arrangement, or journal bearing, allowing for pivotal fore-and-aft movement of hitch plate  130 . Hitch plate  130  includes a latch assembly (not shown) which further includes a jaw assembly specifically adapted to releasably engage and hold a kingpin  115  of a trailer  119  desired to be towed by the towing vehicle  120 . 
     Some fifth wheel hitch assemblies  101  are adjustable axially with respect to the towing vehicle  109  frame. One way of achieving this feature is attach slide rails to the support frame of the hitch and configure the pedestal  155 , upon which the hitch plate and latch assembly is mounted, to slidably engage the slide rails  151   a, b . The conventional design of these slide rails is often a simple flange extending inward of the slide assembly which may be angled metal. Slide rails  151   a, b  are attached to the support frame by fillet welding and by bolts. Stop blocks are used to prevent over-travel of pedestal  155  in slide assembly and are affixed to the ends of slide rails  151   a, b.    
     Prior art stop blocks  105   a - d  are generally rectangular members that are affixed to the end of a slide plate usually with lap welding. A short-coming of this technique is that with such a small block there is a relatively small point of failure. Under large trailer loads, there can be excessive longitudinal forces pulling the hitch aft which may result in disassembly of the stop block from the fifth wheel slide assembly. Further, the attachment helping to support the stop block is limited to the slide plate area. Thus, a stop block is needed which will better withstand such longitudinal forces through distribution of the load. 
     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 stop block for an adjustable fifth wheel hitch comprises a generally rectangular member having a double curve disposed in the member resulting in a long portion of the member and a short portion of the member and such that the long portion of the member is at a higher elevation than the short portion of said member. 
     This 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 stop blocks according to the present invention; 
         FIG. 3A  is a detailed top view of an exemplary stop block according to the present invention; 
         FIG. 3B  is a side view of the stop block shown in  FIG. 3  A; 
         FIG. 3C  is a top view of an exemplary stop block according to another embodiment of the present invention; 
         FIG. 3D  is a cross-section view along line A-A of the exemplary stop block depicted in  FIG. 3C . 
     
    
    
     DETAILED DESCRIPTION 
     The various embodiments of the present invention and their advantages are best understood by referring to  FIGS. 1 through 3D  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. 
     Looking first to  FIGS. 1A-1D , 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  comprising two tines  132   a, b  defining 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 with left and right slide assembles  120   a, b  which is mounted to towing vehicle  109  frame. Slide assemblies  120   a, b  permit longitudinal positioning of fifth wheel hitch assembly  110  with respect to tractor frame, as shown in  FIGS. 1A and 1B . 
     Exemplary slide rail assemblies  120   a, b  are 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  120   a  is attached to the upper surface of left slide rail plate  102   a  and right slide rail  120   b  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  120   a, b . Slide rail plates  102   a, b  and slide rails  120   a, b  each have longitudinal axes which parallel the longitudinal axis of towing vehicle  109 . 
     Referring now to  FIG. 2 , the slide stops of the present invention will be described in detail. Slide stops  205   a - d  are located toward each end of each slide rail plate  102   a, b  and are affixed to both the tie bars and the ends of slide rail plates  102   a, b . Slide stop blocks  205   a - d  prevent over-travel of pedestal  155 . Slide stop blocks  205   a - d  are oriented with respect to slide rail assembly  120  parallel to tie bars  104   a - b , each of the stop blocks having an outward oriented end affixed to the ends of slide rail plates  102   a,b  and an inward oriented end affixed to tie bar  104   a,b . Stop block  205   a - d  is affixed to frame such that a majority of stop block  205   a - d  rests upon slide rail plate  102   a, b  and the remainder rests upon tie bars. 
       FIGS. 3A , B show an exemplary stop block  205  in greater detail where stop block  205  is a plate member comprising a double curve  302  located toward one end of stop block  205  resulting in a short segment  305  and a long segment  307 . When stop block  205  is installed in slide rail assembly, bottom surface of long segment  307  rests upon the top surface of slide rail plate  102  and bottom surface of short segment  305  rests upon the top surface of tie bar  104 , the double curve  302  allowing a step-down in elevation. Thus, double curve  302  permits substantially all, if not all, of the bottom surface of long segment  307  to be seated upon the top surface of tie bar  104 . Likewise, double curve  302  allows substantially all, if not all, of the bottom surface of short segment  305  to be seated upon the top surface of slide rail plate  102 . Long segment and short segment of stop block may be affixed to slide rail plate and tie bar, respectively, by various methods known in the relevant arts, or which may be later developed. One non-limiting example is lap welding, a technique well-known in the art. 
       FIGS. 3C , D depict an alternative stop block  310  where the top surface of stop block  310  departs from the top plane of stop block  310 , as defined by the top edge thereof, forming hollow  315 . Hollow  315  reduces the amount of material out of which stop block is comprised and therefore, results in a reduction of mass. Ridge  317  circumscribing hollow  415  provides lateral and longitudinal support. 
     As described above and shown in the associated drawings, the present invention comprises a stop block for a fifth wheel slide 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.