Patent Abstract:
A drop deck trailer frame includes a front section having a first upper surface, a rear section having a second upper surface lower than the first upper surface, and an improved connection between the front and rear sections which tends to reduce cracking which commonly occurs in drop deck trailer frames due to the stresses in the region of the connection. The connection preferably includes a semicircular weld. In addition, heat treated bent flanges are typically used to provide additional strength. Fasteners such as bolts are also typically used to connect various flanges.

Full Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/571,448, filed Aug. 10, 2012, which is a continuation of U.S. patent application Ser. No. 13/298,434, filed Nov. 17, 2011 (now U.S. Pat. No. 8,256,799), which is a continuation of U.S. patent application Ser. No. 12/902,432, filed Oct. 12, 2010 (now U.S. Pat. No. 8,096,583), which is a continuation of U.S. patent application Ser. No. 12/006,649, filed Jan. 4, 2008 (now U.S. Pat. No. 7,832,767); the disclosures of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The present invention relates generally to flatbed trailers. More particularly, the present invention relates to a drop deck trailer. Specifically, the invention relates to the front connection between the upper and lower decks of the drop deck trailer. 
         [0004]    2. Background Information 
         [0005]    Drop deck trailers are well known in the art and include an upper deck at the front of the trailer and a lower deck which is connected to and extends rearwardly from the upper deck. This configuration allows for the upper to be connected to an elevated hitch such as a fifth wheel while the lower deck may be position at a lower height to provide for additional storage within the height perimeters required by various regulations for roadways and highways. 
         [0006]    One problem which is commonly seen in drop deck trailers is the formation of cracks or other deterioration within the structure connecting the upper and lower decks of the trailer frame due to the inherent forces acting along this region of the frame especially when the trailer is fully loaded. The present invention addresses this and other problems in the art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    In one aspect, the present invention may provide a drop deck trailer frame comprising: a front section having a first upper surface; a rear section having a second upper surface lower than the first upper surface; an S-shaped flange on the front section; an I-beam of the rear section defining the second upper surface and comprising a vertical plate having a top and a bottom, an upper flange secured to the top of the vertical plate and having a front end, and a lower flange secured to the bottom of the vertical plate and having a front end; a first upwardly extending flange which extends from adjacent the front end of the upper flange to adjacent the front end of the lower flange; and a second upwardly extending flange which extends from adjacent the front end of the upper flange to adjacent the front end of the lower flange. 
         [0008]    In another aspect, the invention may also provide a drop deck trailer frame comprising: a front section having a first upper surface; a rear section having a second upper surface lower than the first upper surface; an S-shaped flange on the front section; an I-beam of the rear section defining the second upper surface and comprising a vertical plate having a top and a bottom, an upper flange secured to the top of the vertical plate and having a front end, and a lower flange secured to the bottom of the vertical plate and having a front end; an upwardly extending flange which extends from adjacent the front end of the upper flange to adjacent the front end of the lower flange; and an L-shaped flange adjacent the upwardly extending flange. 
         [0009]    In another aspect, the invention may further provide a drop deck trailer frame comprising: a front section having a first upper surface; a rear section having a second upper surface lower than the first upper surface; a longitudinally extending I-beam of the rear section defining the second upper surface and comprising a vertical plate having a top and a bottom, an upper flange secured to the top of the vertical plate and having a front end, and a lower flange secured to the bottom of the vertical plate and having a front end; a first upwardly extending flange of the rear section which extends from adjacent the front end of the upper flange to adjacent the front end of the lower flange and which has a lower end; a second upwardly extending flange of the front section which extends from adjacent the front end of the upper flange to adjacent the front end of the lower flange, which extends upwardly beyond the upper flange and which has a lower end; a longitudinally extending third flange of the front section which extends below the lower ends of the first and second upwardly extending flanges and includes a generally horizontal tongue which extends rearwardly beyond the lower ends of the first and second upwardly extending flanges and below the lower flange; a plurality of first bolts extending from the first upwardly extending flange to the second upwardly extending flange; and a plurality of second bolts extending from the tongue to the lower flange of the I-beam. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0010]      FIG. 1  is a side elevational view of the drop deck trailer of the present invention hitched to a tractor via a fifth wheel. 
           [0011]      FIG. 2  is a top plan view taken on line  2 - 2  of  FIG. 1  shown the front connection region of the trailer with the upper and lower decks shown in phantom. 
           [0012]      FIG. 3  is a side elevational view of the front connection. 
           [0013]      FIG. 4  is an exploded perspective view of the front connection. 
           [0014]      FIG. 5  is a perspective view of the front connection when assembled. 
           [0015]      FIG. 6  is an end elevational view looking forward on the L-shaped structure of the connection. 
           [0016]      FIG. 7  is a sectional view taken on line  7 - 7  of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    The front connection of the present invention as shown generally at  10  in 
         [0018]      FIGS. 3 and 5 .  FIG. 1  shows front connection  10  as part of a drop deck trailer  12  which is hitched to a towing vehicle in the form of a tractor  14  via a fifth wheel hitch  16 . Trailer  12  includes front and rear sections  18  and  20  which respectively include upper and lower decks  22  and  24 . A vertical decking member  38  ( FIGS. 1 ,  3 ) is connected to and extends between the rear end of upper deck  22  and the front end of lower deck  24  to define the boundary therebetween. Member  38  and decks  22  and  24  may be formed of metal, wood or other suitable materials. As shown in  FIG. 2 , trailer  12  includes a frame comprising first and second longitudinally extending parallel rails  26  and  28  connected adjacent the front ends by a cross member  30  which extends axially therebetween and serves as a hitch support on which a hitch member  32  is mounted for connection to fifth wheel  16 . Adjacent the rear ends of rails  26  and  28 , a wheel mounting structure  34  is connected to and extends axially between rails  26  and  28  to support wheels  36 , as shown in  FIG. 1 . Rails  26  and  28  are substantially identical or are mirror images of one another and thus each include a front connection  10 . Each of rails  26  and  28  is formed of metal and typically the primary components are formed of an aluminum alloy. The use of an aluminum alloy provides for a relatively low cost and light weight structure for supporting decks  22  and  24  and loads carried thereon. 
         [0019]    Referring to  FIGS. 3-5 , connection  10  is described in greater detail. Rail  26  includes an L-shaped structure comprising an L-shaped plate  40 , an L-shaped flange  42  connected to plate  40  and an S-shaped flange  44  connected to plate  40 . Plate  40  is substantially flat and substantially vertically oriented along a vertical longitudinally extending plane. Plate  40  includes a generally horizontal first leg  46  which extends laterally in the longitudinal direction and a generally vertical second leg  48  which is connected to the rear end of first leg  46  and extends downwardly therefrom. Plate  40  has an L-shaped edge  50  including a generally horizontal edge segment  52  which extends laterally in a longitudinal direction and faces upwardly. Edge  50  further includes a convex arcuate edge segment  54  which is connected to the rear end of segment  52 , faces upwardly and rearwardly, and curves downwardly to a downwardly extending generally vertical edge segment  56 . Opposite L-shaped edge  50 , plate  40  has an S-shaped edge  58  which includes a downwardly facing generally horizontal edge segment  60  which extends laterally in the longitudinal direction. A concave arcuate edge segment  62  curves downwardly from the rear of segment  60  and faces forward and downward. A short vertical edge segment  64  extends downwardly from arcuate segment  62  and serves as a brief transition to another arcuate segment  66  which is convex and curves in the opposite direction from segment  62  and thus downwardly and rearwardly. Vertical segment  64  faces forward while arcuate segment  66  faces forward and downward. A generally horizontal edge segment  68  extends rearwardly from arcuate segment  66  and faces downwardly. Segment  68  intersects edge segment  56  of L-shaped edge  50  at the lower rear corner of plate  40  and is substantially perpendicular to segment  56 . 
         [0020]    With continued reference to  FIGS. 3-5 , an L-shaped T-bar  70  extends along and is connected to the mating L-shaped edge  50  of plate  40 . As best shown in  FIGS. 4 and 5 , T-bar  70  includes an L-shaped web  72  which serves as the upright of the T-shaped cross section and an L-shaped crossbar  74  which serves as the top of the T-shaped cross section and extends outwardly from web  72  in opposite directions. Crossbar  74  serves as L-shaped flange  42  in the exemplary embodiment. Crossbar  74  includes a generally horizontal segment  76  and arcuate segment  78  curving downward therefrom and a generally vertical segment  80  extending downwardly from arcuate segment  78  so that segments  76 ,  78  and  80  extend in an analogous manner respectively to edge segments  52 ,  54  and  56  of the L-shaped edge  50 . Thus, web  72  has an L-shaped edge  82  which mates with 
         [0021]    L-shaped edge  50  of plate  40 . Edge  82  thus includes a generally horizontal segment  84 , a concave arcuate segment  86  and a vertical segment  88  which respectively mate with edge segments  52 ,  54  and  56  of L-shaped edge  50  of plate  40 . Horizontal segment  84  faces downwardly, arcuate segment  86  faces downwardly and forward and vertical segment  88  faces forward. L-shaped edge  82  is connected to L-shaped edge  50  via an L-shaped continuous weld  90  which thus has analogous horizontal, arcuate and vertical segments. Segment  76  has a substantially horizontal upper surface which serves as the upper surface of front section  18  of the frame upon which upper deck  22  is seated and secured. 
         [0022]    An S-shaped T-bar  92  extends along and has a mating configuration with S-shaped edge  58  and is connected to plate  40  along edge  58 . T-bar  92  has an S-shaped web  93  and an S-shaped crossbar  95  connected to and extending outwardly in opposite directions from web  93 . Crossbar  95  thus forms an S-shaped flange  44  in the exemplary embodiment. T-bar  92  includes a generally horizontal segment  94 , an arcuate segment  96  curving downwardly and rearwardly therefrom, a short vertical segment  98  at the bottom of arcuate segment  96 , an arcuate segment  100  curving downwardly and rearwardly from vertical segment  98  in the opposite direction of segment  96 , and a generally horizontal segment  102  extending rearwardly from arcuate segment  100 . Web  93  thus includes an S-shaped edge  104  including a generally horizontal longitudinally extending edge segment  106 , a convex arcuate edge segment  108  curving downwardly and rearwardly therefrom, a short vertical edge segment  110  extending down from segment  108 , a concave arcuate edge segment  112  curving downwardly and rearwardly from segment  110 , and a generally horizontal edge segment  114  extending rearwardly from arcuate segment  112 . Edge segment  106  faces upwardly, arcuate edge segment  108  faces upwardly and rearwardly, vertical edge segment  110  faces rearwardly, arcuate edge segment  112  faces upwardly and rearwardly, and horizontal segment  114  faces upwardly. Thus, edge segments  106 ,  108 ,  110 ,  112  and  114  respectively matingly fit with segments  60 ,  62 ,  64 ,  66 , and  68  of S-shaped edge  58  of plate  40 . S-shaped edges  58  and  104  are welded to one another via a continuous S-shaped weld  115 . 
         [0023]    A flat and generally horizontal tongue  116  extends rearwardly from a lower end  118  of vertical segment  80  of L-shaped T-bar  70  and is formed from a portion of crossbar  95  from which web  93  has been removed. More particularly, web  93  has a rearmost terminal end  120  which abuts web  72  of L-shaped T-bar  70  adjacent lower end  118  thereof. Web  93  has been removed rearwardly of terminal end  120  so that only crossbar  95  continues to project rearwardly in the form of tongue  116 . Lower end  118  of segment  80  abuts the upper surface of segment  102  at the front of tongue  116 , and thus L-shaped flange  42  at its lowest and rearmost portion intersects S-shaped flange  44  along horizontal segment  102  to form an inverted T-shaped intersection. A first row of longitudinally spaced through holes  122  is formed in tongue  116  generally along one side thereof. Likewise, a second row of longitudinally spaced through holes  124  formed in tongue  116  along the opposite side thereof so that the row of holes  124  is axially spaced from the row of holes  122  and holes  124  are also longitudinally offset from holes  122 . Holes  122  and  124  extend from the top surface of tongue of  116  to the bottom surface thereof. Another row of vertically spaced through holes  126  ( FIGS. 4 ,  6 ) is formed in vertical segment  80  of crossbar  74  extending from the front to the rear surface thereof and positioned on the one side of web  72  and plate  40 . Likewise, another row of vertically spaced through holes  128  ( FIG. 6 ) is formed in vertical segment  80  of crossbar  74  on the other side of web  72  and plate  40 . 
         [0024]    In the exemplary embodiment, each of T-bars  70  and  92  is formed in an extrusion process. The extruded T-bars are bent to form their respective arcuate segments and L-shaped and S-shaped configurations typically at room temperature. A portion of web  93  is cut off or otherwise removed from the corresponding section of crossbar  95  to form tongue  116  as previously noted. Once the extruded T-bars are in their appropriate L-shaped and S-shaped configurations, they are heat treated in order to provide additional strength and eliminate internal stresses caused by the bending process. The heat treated T-bars are subsequently welded to the L-shaped and S-shaped edges  50  and  58  of plate  40  at welds  90  and  115  to form the rigid L-shaped structure of front section  18 . 
         [0025]    Referring to  FIG. 4 , rail  26  further includes a rigid connection member  130  used in forming front connection  10 . Connection member  130  is formed from a T-bar and includes a semicircular flat plate or web  132  and a straight vertically extending crossbar  134  connected to and extending perpendicularly outwardly in opposite axial directions from web  132 . Web  132  lies in a substantially vertical longitudinally extending plane parallel to L-shaped plate  40  and is typically coplanar therewith. Crossbar  134  has upper and lower generally horizontal ends  136  and  138 , first and second vertically extending lateral edges  140  and  142  and vertically extending front and rear surfaces  144  and  146 . A first row of vertically spaced through holes  148  is formed in crossbar  134  on one side of web  132  extending from front surface  144  to rear surface  146  and respectively alignable with holes  126  in vertical segment  80 . Likewise, a second row of holes  150  is formed in crossbar  134  on the other side of web  130  and respectively alignable with holes  128  ( FIG. 6 ) in vertical segment  80 . Web  130  has a straight vertically extending base  152  ( FIG. 3 ) which is connected to rear surface  146  of crossbar  134  and extends from upper end  136  to lower end of  138 . Web  130  extends rearwardly from base  152  and terminates at a semicircular edge  154  which curves rearwardly and downwardly from upper end  136  to a rearmost point  156  and then downwardly and forward to lower end  138 . 
         [0026]    With reference to  FIGS. 3-5 , rail  26  includes a generally horizontal beam  158  in the form of an I-beam which is connected to the L-shaped structure and connection member  130  and extends rearwardly therefrom. I-beam  58  includes a flat vertical plate or web  160 , an upper flange  162  connected to and extending outwardly in opposite directions from the top of web  160 , and a lower flange  164  connected to the bottom of web  160  and extending outwardly in opposite directions therefrom. Web  160  lies in a substantially vertical longitudinally extending plane parallel to plate  40  and web  132  and is typically coplanar therewith. Upper flange  162  has a front end  166 , an upper surface  168  and a lower surface  170  from which web  160  extends downwardly. Upper surface  168  is substantially horizontal and serves as the upper surface of rear section  20  of the frame on which rear lower deck  24  is seated and secured. Lower flange  164  has a front end  172 , an upper surface  174  from which web  160  extends upwardly, and a lower surface  176 . A first row of through holes  178  is formed in lower flange  164  adjacent front end  172  thereof and extends from upper surface  174  to lower surface  176  on one side of web  160 . A second row of longitudinally spaced holes  180  is likewise formed in lower flange  164  on the other side of web  160 . Holes  178  are respectively alignable with holes  122  while holes  180  are respectively alignable with holes  124 . 
         [0027]    In the exemplary embodiment, I-beam  158  includes an inverted T-bar including lower flange  164  and a lower half  182  of web  160 . I-beam  158  further includes another T-bar which includes upper flange  162  and an upper half  184  of web  160 . Lower and upper halves  182  and  184  are connected to one another along a substantially horizontal longitudinally elongated weld  186 . A front semicircular opening  188  is formed at the front of web  160  and extends rearwardly therefrom and is bounded by a semicircular concavely curving front edge  190  having a lower front end  192  spaced a short distance rearwardly from front end  172  of crossbar  164  and an upper front end  194  ( FIG. 3 ) which is likewise spaced rearwardly a short distance from front end  166  of upper flange  162 . Weld  186  intersects front edge  190  at its midpoint so that a quarter circle of edge  190  is form in lower half  182  and a quarter circle is formed in upper half  184 . In the exemplary embodiment, web  160  has a height D 1  ( FIG. 3 ) defined between lower surface  170  of upper flange  162  and upper surface  174  of lower flange  164 . Weld  186  is at the midway point between surfaces  170  and  174  so that lower half  182  and upper half  184  of plate  160  each have a height D 2  which is one half of height D 1 . In the exemplary embodiment, point  156  of web  132  and rear surface of  152  of crossbar  134  define therebetween a normal distance D 3  which is equal to distance D 1 . Thus, connection member  130  may be formed of a T-bar having the same cross sectional configuration as that of the T-bars which are used to form I-beam  158 . 
         [0028]    When the various components are assembled as shown in  FIGS. 3 and 5 , web  132  of connection member  130  is received within semicircular opening  188  and crossbar  134  is received between upper and lower crossbars  162  and  164  adjacent their respective front ends  166  and  172  and respectively forward of front ends  194  and  192  of edge  190 . Thus, upper and lower ends  136  and  138  of crossbar  134  define a distance which is nearly the same as distance D 1  although typically slightly less so that crossbar  134  can easily be received in between and welded to flanges  162  and  164 . The convexly curving semicircular edge  154  of web  132  is of a mating configuration with concave semicircular edge  190  of web  160 . Edge  154  and edge  190  lie along a circular path having substantially the same diameter although the diameter along which edge  154  lies may be slightly less to easily accommodate web  132  within opening  188 . Once connection member  130  is positioned within space  188 , edge  154  is welded to edge  190  along a semicircular weld  196  while upper and lower ends  136  and  138  of crossbar  132  are welded respectively to lower surface  170  of upper crossbar  162  and upper surface  174  of crossbar  164 . Fasteners in the form of bolts  198  and nuts  200  are typically used to form part of front connection  10 . More particularly, bolts  198  are received through aligned holes  126  and  148  and threadedly engaged by respective nuts  200 . Likewise, bolts  198  extend through aligned holes  128  and  150 . Bolts  198  also extend through aligned holes  122  and  178  as well as through aligned holes  124  and  180 . 
         [0029]    When assembled, flange  134  of connection member  130  and vertical segment  80  of flange  42  are secured to one another by the respective bolts and nuts to form a vertical parallel pair of abutting flanges. Likewise, tongue  116  and the front portion of lower flange  164  of I-beam  158  are secured by respective bolts and nuts to form a second pair of parallel abutting flanges which extend transversely to and most typically perpendicularly to flanges  134  and  80 . Semicircular weld  196  extends within the right angle formed between these two pairs of parallel flanges with its lower quarter circle portion disposed directly between the two pairs of flanges. 
         [0030]    Thus, front connection  10  provides a substantially improved connection between the front and rear sections  18  and  20  of the frame of drop deck trailer  12 . The semicircular weld  196  helps to reduce cracking in the connection by minimizing stress points found in linear welds. In addition, the L-shaped and S-shaped structures of flanges  42  and  44  help provide structural integrity to the connection. The heat treatment of the T-bars forming flanges  42  and  44  likewise provide additional strength and reduce or eliminate built in stresses which would otherwise remain from the bending of these two bars. The L-shaped and S-shaped welds along flanges  42  and  44  provide further structural integrity to the connection. The use of tongue  116  which is formed integrally during extrusion with the lower T-bar forming flange  44  provides additional strength to the connection between S-shaped flange  44  and I-beam  158 . These and other aspects of front connection  10  provide a substantially improved connection. 
         [0031]    In the foregoing description, certain terms have been used for brevity, clearness, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. 
         [0032]    Moreover, the description and illustration of the invention is an example and the invention is not limited to the exact details shown or described.

Technology Classification (CPC): 1