Abstract:
A tractor trailer having an adjustable wheel assembly, the trailer comprising at least two laterally spaced frame members. A plurality of openings are located in the frame members, with each opening having a flange section structured to receive a wheel assembly locking-pin. The flange section increases the load-bearing area of each frame member opening.

Description:
FIELD OF THE INVENTION 
     The field of the present invention relates to trailers used for overland transport of goods. More particularly, the present invention relates to adjustable wheelbase trailers. 
     BACKGROUND OF THE INVENTION 
     Commercial tractors and other types of trucks transport freight or goods using trailers such as flatbeds, platform trailers, enclosed vans, container transport chassis or other suitable types of trailers. Many of these transport vehicles have adjustable wheel assemblies that allow the operator to change the trailer or vehicle wheelbase. The wheelbase must be adjusted for a variety of reasons including decreasing the turning radius and improving weight distribution to meet Federal axle-weight requirements. 
     As illustrated in FIGS. 1 and 2, a tractor trailer used  10  includes a front support strut assembly  20  and an adjustable wheel assembly or “bogie”  25  joined by at least two frame rails  15 . The front support  20  and rails  15  form a main trailer or chassis structure to which the bogie  25 , is slidably attached. The bogie  25  comprises at least one, and usually two axles with four wheels rotatably mounted to each axle. When the operator wants to change the trailer  10  wheelbase, the operator changes the location of the bogie  25  relative to the main trailer structure. 
     The bogie  25  has bogie lock pins  35  receivable into bogie lock pin holes  30 , which extend through the rails  15 . Accordingly, when the bogie lock pins  35  are inserted and locked into the boogie lock pin holes  30 , the bogie  25  is securely positioned and held. 
     The bogie  25  location is usually moved by locking the wheels, retracting the bogie lock pins  35  from the bogie lock pin holes  30  and using the tractor to slide the trailer frame rails  15  on the bogie rails  60 . Once the bogie  25  has been positioned in the desired location, the bogie lock pins  35  are re-inserted into the bogie lock pin holes  30 . Typically, at least two bogie lock pins  35  are used, one for each rail  15 . 
     Referring to FIGS. 2-4, a bolster strip  45  is welded around the bogie lock pin holes  30  to reinforce the frame rail  15  and bogie lock pin holes  30  against the loads imparted through the bogie lock pins  35  and into the frame rail  15  by the bogie  25 . When inserted into the bogie lock pin holes  30 , the bogie lock pins  35  only engage a thin ring of frame rail  15  material that comprises the perimeter of the bogie lock pin hole  30 . Substantially all of the loads encountered by the bogie  25  are transferred to the trailer  10  through this thin ring of frame rail  15  material. 
     The bolster strip  45  is generally welded to the outside of the frame rail  15  with the frame rail aperture  31  having a larger diameter than the bogie lock pin hole  30 . This creates a bolster lip  50 , illustrated in FIGS. 3-4. As a result, when the bogie  25  is repositioned to change the trailer wheelbase, the bogie lock pin  35  oftentimes contacts the bolster lip  50  and fails to properly engage the bogie lock pin hole  30 . When the bogie lock pin  35  fails to properly engage the bogie lock pin hole  30 , an extremely unsafe situation is created because the bogie  25  is no longer positively attached to the frame rails  15 . 
     In addition, moisture accumulates between the bolster strip  45  and the frame rail  15 , causing corrosion around the bogie lock pin holes  30  and decreasing the structural strength and integrity of the frame rails  15  and the bolster strip  45 . Also, because substantially all the bogie  25  loads are carried by the thin ring of bolster strip  45  material, the bogie lock pin hole  30  perimeters become oval, which introduces play or slack in the bogie  25 , increasing the possibility of disengagement of the bogie  25  from the trailer  10 . Also, corroded frame rails  15  can fail when the trailer  10  is loaded with cargo, and this failure can occur while the trailer  10  is operating in highway traffic, possibly resulting in a serious accident. 
     Therefore, there exists a need for an adjustable wheelbase trailer that can withstand the loads imparted by a bogie, without deformation of the bogie lock pin holes, and can also consistently ensure positive engagement of the bogie to the trailer. 
     SUMMARY OF THE INVENTION 
     In order to overcome the deficiencies with known, conventional bogie location systems, an adjustable wheelbase trailer is provided. Briefly, the present invention solves the problem of a bogie lock pin failing to properly engage a bogie lock pin hole. In addition, the present invention solves the problem of bolster strip corrosion and the subsequent structural deformation of the bolster strip, bogie lock pin holes and the underlying frame rail. 
     An adjustable wheelbase trailer constructed according to the present invention provides a way to consistently engage the bogie lock pins into the bogie lock pin holes. Moreover, the present invention removes the bolster strip thereby eliminating corrosion of the trailer frame rails and bogie lock pin hole perimeters, and in such manner trailer life is increased and manufacturing costs are reduced. 
     Broadly, the present invention provides a method to remove the bolster strip while maintaining sufficient bogie lock pin hole strength to prevent deformation. In addition, the invention improves engagement of the bogie lock pins in the bogie lock pin holes. 
     More specifically, one embodiment of the invention forms a flanged bogie lock pin hole in a trailer frame member by punching an hole in the trailer frame member, deforming a perimeter area of the hole, and extruding the deformed perimeter area so that the perimeter of the extruded hole is larger than the punched hole. The extruded material thus forms a flange which the bogie lock pin engages. 
     Another embodiment of the invention comprises a trailer having an adjustable wheel assembly, the trailer comprising at least two laterally spaced frame members. A plurality of openings are located in the frame members, with each opening having a flange section structured to receive an adjustable wheel assembly bogie lock pin. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The nature, goals, and advantages of the invention will become more apparent to those skilled in the art after considering the following detailed description when read in connection with the accompanying drawing in which like reference numerals identify like elements throughout and wherein: 
     FIG. 1 is a side elevation view of a conventional tractor trailer employing an adjustable wheel assembly; 
     FIG. 2 is a perspective view of the conventional wheel assembly illustrated in FIG. 1; 
     FIG. 3 is a side elevation view of the conventional trailer frame rail of FIG. 2, illustrating a reinforcement plate and a misaligned lock pin; 
     FIG. 4 is a cross-section taken along cutting plane  4 — 4  of FIG. 3; 
     FIG. 5 is a side elevation view of a tractor trailer constructed according to one embodiment of the present invention; 
     FIG. 6 is a cross-sectional view of a tractor trailer frame rail of FIG. 5, illustrating a locating hole constructed according to one embodiment of the present invention; 
     FIG. 7 is a cross-sectional view of an alternative embodiment tractor trailer frame rail, illustrating a locating hole constructed according to a second embodiment of the present invention; 
     FIG. 8 is a cross-sectional view of a method of making a start hole according to the present invention; 
     FIG. 9 is a cross-sectional view of a method of deforming a perimeter area of the start hole illustrated in FIG. 8; 
     FIG. 10 is a cross-sectional view of a method of forming a flanged aperture from the deformed perimeter area illustrated in FIG. 9; and 
     FIG. 11 is a flow chart illustrating a method of making a flanged trailer frame rail locating hole according to the present invention. 
    
    
     It will be recognized that some or all of the Figures are schematic representations for purposes of illustration and do not necessarily depict the actual relative sizes or locations of the elements shown. 
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following paragraphs, the present invention will be described in detail by way of example with reference to the attached drawings. Throughout this description, the preferred embodiment and examples shown should be considered as exemplars, rather than as limitations on the present invention. 
     An adjustable wheelbase trailer  70  in accordance with one embodiment of the invention is illustrated in FIG.  5 . The adjustable trailer  70  includes frame rails  115 , a slideable wheel assembly or bogie  25  and flanged bogie lock pin holes  75  located in the frame rails  115 . The distance  40  between bogie lock pin hole centers can range from about 4 to 6 inches depending upon the trailer requirements, and the number of bogie lock pin holes or openings  75  can vary from about 6 to about 27. 
     As used herein, a trailer is defined to include adjustable wheelbase trailers, platform trailers, container transport chassis, bare chassis, enclosed van trailers and other types of trailers. 
     The bogie  25  can be adjustably positioned on the frame rails  115  by locking the wheels, retracting the bogie lock pins  35 , and moving the frame rails  115  to change the position of the bogie  25  relative to the frame rails  115 . When the desired wheelbase is reached, the bogie lock pins  35  are inserted into the flanged bogie lock pin holes  75 . 
     The bogie lock pin holes  75  include a flange or lip or radiused projection  85 , illustrated in FIGS. 6 and 7. In one embodiment, the flange height or depth is about 1.5 times greater than the thickness  90  of the S-shaped frame rail  117  (FIG.  7 ). The 1.5 ratio is also employed on the I-beam frame rail  115  (FIG.  6 ). However, it will be appreciated that this ratio could vary from about 1 to 1 (flange height equivalent to frame thickness  90 ) to about 3 to 1 (flange height about three times greater than frame thickness  90 ), depending upon the thickness of the frame rail  115  and the desired flange size. Accordingly, the adjustable wheelbase trailer  70  of one embodiment of the present invention does not need the undesirable welded bolster strip of the conventional bogie. 
     FIG. 6 depicts a bogie lock pin hole in a web of an I-beam frame rail  115  and FIG. 7 illustrates a bogie lock pin hole in an S-shaped frame rail  117 . It will be appreciated that the flanged bogie lock pin holes  75  of the present invention can also be employed in other suitable types of frame rails, depending on the trailer  70  requirements. In addition, the thickness  90  of the I-beam frame rails  115  can vary from about 0.15 inches to about 0.3 inches, depending upon the desired load carrying capacity of the trailer  70 . 
     The flanged bogie lock pin hole  75  of the present invention supports the bogie lock pin  35  and increases the structural strength of the bogie lock pin hole  75  by increasing the load bearing area of the bogie lock pin hole  75 . In contrast to a conventional bogie lock pin hole which typically only has a thin ring of material, the flanged bogie lock pin hole  75  constructed according to the present invention comprises a flange height that distributes the bogie lock pin  35  load over the entire flange, thereby greatly increasing the load distribution area, and thus decreasing the stress encountered by the flanged bogie lock pin hole  75 . This substantially eliminates the generation of oval holes and therefore eliminates bogie lock pin  35  play. Moreover, because the bolster strip  45  is eliminated, corrosion is eliminated as moisture pockets cannot form between the bolster strip  45  and the frame rail  15 . 
     Referring to FIGS. 6-7, in contrast to conventional bogie lock pin holes  30 , one embodiment of the flanged bogie lock pin hole  75  constructed according to the present invention has a hole perimeter radius  80  that facilitates insertion of the bogie lock pin  35  into the bogie lock pin hole  75 . Because the bolster bar  45 , and thus the bolster lip  50  is eliminated from the present invention, the bogie lock pins  35  do not catch on the bolster lip  50 . A preferred embodiment flanged bogie lock pin hole  75  has a diameter of about 1⅞ of an inch. However, it will be appreciated that the bogie lock pin hole diameter can vary depending upon the diameter of the bogie lock pin  35 . For example, the diameter of the bogie lock pin hole  75  may range between about 1.5 to about 2.5 inches. 
     Referring to FIGS. 8-10 a flanged bogie lock pin hole  75  according to the present invention is manufactured by punching a start hole  95  in frame rail  115 . In one embodiment of the flanged bogie lock pin hole  75 , the start hole  95  is about 1.5 inches in diameter. It will be appreciated that the start hole can vary in diameter depending upon the requirements for the flanged bogie lock pin hole diameter. In a preferred embodiment the start hole  95  is formed by a start hole punch  100  that punches the start hole  95  from the frame rail  115  when the start hole punch  100  is positioned over a start hole punch support plate  105 . 
     Illustrated in FIG. 9, after the start hole  95  is formed, an intermediate punch  110  is used to form an intermediate flange  121  around the start hole  95 . The diameter of the intermediate flange  121  is determined by the desired flange height. As discussed above, the flange height can vary from about 1 to about 3 times the frame thickness  90 . Frame rail  115  is placed over the support plate  113  and the intermediate punch  110  contacts the frame  115 , forming the intermediate flange  121 . An intermediate flange angle  120  of about 45 degrees is formed relative to the frame rail surface  125 . It will be appreciated that the intermediate flange angle  120  can vary, depending upon the punch, and the desired intermediate flange deformation. 
     In FIG. 10 the final punching process is completed with the final flange punch  160 . The final flange punch  160  can either use the intermediate punch support plate  113  or a final flange punch support plate  130 . A final flange angle  135  of about 90 degrees is formed in the frame rail  115  after the final punch  160  deforms the frame rail  115 . In this embodiment, the height of the flange  85  is now about 1.5 times the frame rail thickness  90 . 
     FIG. 11 illustrates a preferred method of forming a flanged bogie lock pin hole  75  according to the present invention. In step 140 a start hole  95  is punched in the frame rail  115 . It will be appreciated that the frame rail  115  can be an I-beam, an S-beam  117  or any other suitable trailer beam or frame rail. In step 145 an intermediate punch  110  is used to form an intermediate flange  121 . In step 150 a final punch  160  is used to form a final flange  85 . In step 155 flange cracks (not shown) which can form at the outer periphery of the flange are removed by a grinding or other suitable abrading process. In an alternative method of forming a flanged bogie lock pin hole  75  according to the present invention, a progressive die or punch is employed wherein the frame rail  115  passes over the progressive die stations and the start hole  95  is punched, the intermediate flange  121  is formed, the final flange  85  is formed and any flange cracks are removed in a series of steps. It will be appreciated that other types of hole forming operations could also be employed to form the flanged hole  75 . 
     One skilled in the art will appreciate that the present invention can be practiced by other than the preferred embodiments which are presented in this description for purposes of illustration and not of limitation, and the present invention is limited only by the claims that follow. It is noted that equivalents for the particular embodiments discussed in this description may practice the invention as well.