Abstract:
A stake, bunk and bunk pocket are used to constrain logs on the bed of a truck or trailer. The stakes can be inserted or removed from the bunk pocket which is attached to the end of the bunk. All elements are composed of lightweight hardened aluminum. The bunk and the stake are formed using an extrusion process and have internal members or webs that add additional strength and are also formed during the extrusion process. Stakes and bunks come in various lengths to accommodate the various sizes of vehicles, the load capacity of the vehicles, and the density and corresponding weight of the logs. This invention makes stakes easier to work with as their weight is significantly reduced. These stakes, due to their reduced weight, may be repositioned from the ground  16 . Bunks, bunk pockets and stakes are all resistant to corrosion, exceed federal requirements for load carrying capacity and allow for a reduction in gross vehicle weight thereby offering greater load capacity before the vehicle reaches its maximum legal weight.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a stake, bunk and bunk pocket used to constrain logs on the bed of a truck or trailer. 
     2. Description of the Background Art 
     Most logging trucks or trailers have for many years used different materials for supporting the logs on top of the bed of the vehicles during the transportation of freight. In the beginning, wood was used for the stake materials which are vertically extending posts which fit into lateral fixtures. These lateral fixtures are referred to as bunks. Each bunk has an opening in both ends referred to as a bunk pocket. The bunks are spaced along the length of the vehicle, and the bunk pockets are sized to match the stakes which fit vertically into the bunk. Federal regulations specify that stakes must have a specific yield strength, making wood stakes obsolete. 
     The prior art has focused on methods of extending the stakes as in U.S. Pat. Nos. 3,811,724, 4,668,000, 3,712,639 and 5,611,286. These patents focused on extending the height of the stakes using mechanical or hydraulics methods, and did not focus on the unique properties of the materials used to create the stake. Stakes are normally used to constrain high or low density logs on logging trucks or trailers. The density of the logs determine the length of the stake. The type of stake today is typically steel, with some stakes being telescoping. Depending on the density of the logs and the quantity of logs, stakes may need to be changed to longer or shorter ones on a given load so they conform to federal safety standards and still offer the maximum load carrying capacity. 
     Logging companies prefer to place the maximum load on each truck or trailer to maximize the cost effectiveness of each load. Typically trucks or trailers have had to replace the existing stakes with new stakes of greater height or strength depending on whether they are carrying high or low density logs. Working and moving steel stakes is difficult because of their weight and operators must get up on the bed of the vehicle to reposition the stakes. When the truck or trailer has not met the maximum weight limit based on load restrictions, some steel stakes can be extended either manually or automatically to increase or decrease the load capacity. 
     Typically steel and wood have had to be extremely heavy to provide the necessary strength to constrain the load. This cuts down on actual deliverable cargo since the weight of the stakes displaces some of the deliverable cargo. Heavy, bulky stakes are difficult to manage or control and create a more hazardous condition for workers adding to the total cost of hauling logs due to injuries and lost time. Normally, aluminum or other lightweight metals do not have the strength to support the heavy loads inherent in the logging industry. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a stake, bunk, and bunk pocket used to constrain logs on the bed of a truck or trailer. The stakes can be inserted or removed from the bunk pocket which is attached to the end of the bunk. All elements are composed of lightweight hardened aluminum. The bunk and the stake are formed using an extrusion process and have internal web members that add additional strength and are also formed during the extrusion process. The stakes and bunks come in various lengths to accommodate the various sizes of vehicles, the load capacity of the vehicles, the density and corresponding weight of the logs. 
     This invention makes stakes easier to work with as their weight is significantly reduced. These stakes, due to their reduced weight, may be repositioned from the ground. The stakes, bunks, and bunk pockets are all resistant to corrosion, exceed federal requirements for load carrying capacity and allow for a reduction in gross vehicle weight thereby offering greater load capacity before the vehicle reaches its maximum legal weight. 
     The instant invention has a unique structural and material combination allowing for reduced weight, repositioning from the ground, corrosion resistance, safety, ease in handling, reduces work time lost due to injuries, and strength capacity that exceeds the federal regulations governing vehicles hauling logs. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein: 
     FIG. 1A is a side view of a trailer showing a plurality of stakes positioned along the side thereof; 
     FIG. 1B is a rear view of the trailer showing a plurality of stakes positioned along the end thereof; 
     FIG. 2 is an end view of a truck or trailer frame including vertical stakes, bunk pockets, and bunks of the present invention; 
     FIG. 3 is a perspective view showing a vertical stake, a bunk pocket, and a bunk of the present invention in an assembled condition; 
     FIG. 4 is an end view of a stake of the present invention; 
     FIG. 5 is an end view of a second embodiment of a stake of the present invention; 
     FIG. 6A is an exploded perspective view of a first embodiment of a stake extension of the present invention; 
     FIG. 6B is a perspective view of the first embodiment of the stake extension of the present invention in an assembled condition; 
     FIG. 6C is an exploded perspective view of a second embodiment of a stake extension of the present invention; 
     FIG. 6D is a perspective view of the second embodiment of the stake extension of the present invention in an assembled condition; 
     FIG. 7 is an end view of the bunk of the present invention; 
     FIG. 8 is an end view of a second embodiment of a bunk of the present invention; 
     FIG. 9A is an exploded perspective view of a first embodiment of a bunk extension of the present invention; 
     FIG. 9B is a perspective view of the first embodiment of the bunk extension of the present invention in an assembled condition; 
     FIG. 9C is an exploded perspective view of a second embodiment of a bunk extension of the present invention; 
     FIG. 9D is a perspective view of the second embodiment of the bunk extension of the present invention in an assembled condition; 
     FIG. 10 is an exploded view of the bunk pocket of the present invention; 
     FIG. 11 is an exploded view of a second embodiment of a bunk pocket of the present invention; 
     FIG. 12 is an exploded view of a third embodiment of a bunk pocket of the present invention; 
     FIG. 13 is a perspective view of a fourth embodiment of a bunk pocket of the present invention; 
     FIG. 14A is a perspective view showing the stake secured to the bunk of the present invention; 
     FIGS. 14B and 14C are detail views showing the stake securing pin and bunk of FIG. 14A; 
     FIG. 15A is a rear view of a trailer showing a stake being repositioned; and 
     FIG. 15B is a side view of a trailer showing a stake being repositioned. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This is a description of the preferred stake  20 , bunk  40 , and bunk pocket  60 . However, it is to be understood that the present invention is not limited to the preferred materials, structural configurations or dimensions as described herein, and that the invention can be changed or modified without departing from the scope of this invention. 
     As shown in FIG. 1, a plurality of stakes  20  are positioned along the sides of a trailer  10  and along the end of the trailer  10  for constraining the logs  12 . 
     Referring now to FIG. 2, an end view of the trailer  10  reveals that a bunk  40  extends across the width of the frame  14  of the trailer  10 . The stakes  20  are attached to the ends of the bunk  40  by inserting an end of the stake  20  into a bunk pocket  60  fixed to the end of the bunk  40 . The bunk  40  can be seen positioned flush with the top of the frame  14  of the truck or trailer  10 , yet underneath the truck bed. A plurality of bunks  40  are typically attached under, or on top of a frame  14  of the truck or trailer  10  in multiples and extend perpendicular to the length of the truck or trailer  10 . 
     FIG. 3 illustrates the vertical stake  20  inserted into the bunk pocket  60  which is attached at the end of the bunk  40 . The stake  20  is vertically positionable in the horizontal bunk pocket  60 . Note that the bunk  40  would continue under the bed of the truck or trailer  10 , and have a bunk pocket  60  and stake  20  inserted in the opposite end as shown in FIG.  2 . The bunk  40  shown has a 4000 Lb. uniformly distributed weight limit. 
     FIG. 4 is an end view of the extruded stake  20 , which shows an internal wall or web  24  extending centrally across the stake  20 . The web  24  transverses the interior of the stake  20  from front to back. The stake  20  is manufactured using an extrusion method, from aluminum or other lightweight metals or materials. 
     In this example, the overall width of the stake  20  is 3.00″, and the overall depth of the stake  20  is 4.00″. The thickness of the wails is 0.29″, and the web  24  has a thickness of 0.29″. The web  24  is formed during the extrusion process, and extends the complete length of the interior of the extruded stake  20 . The extruded stake  20  has radiused corners  30 , 32 . The radius of the inside corners  30  is 0.29″, and the radius of the outside corners  32  is 0.50″. The web  24 , along with the radiused corners, adds significant strength to the stake  20 . It should be noted that the present invention is not limited to these particular dimensions. 
     FIG. 5 shows an end view of an alternate embodiment of the stake  20  of the present invention The stake  20  of FIG. 5 is a lightweight, extruded webbed stake  20  with not only a first web  26  extending perpendicular to the force of the load, but also a second web  28  extending parallel to the force of the load to further increase the dimensional stability and strength of the stake  20 . 
     As shown in FIGS. 6A-6D, the stakes  20  may be extended through the use of extensions devices. FIG. 6A illustrates a stake  20  with a permanent extension block  88  welded to the stake  20 . An extension  90  to the stake  20  is located immediately above the extension block  88 . FIG. 6B illustrates a stake  20  with the extension block  88  welded to the top of the stake  20 , and the extension  90  secured to the extension block  88  by a pin  84  in position with a lynch pin  86  which will secure the pin  84 . FIG. 6C illustrates a stake  20  in a vertical position with an extension block  92  located above the stake  20 . An extension  90  to the stake  20  is located immediately above the extension block  92 . FIG. 6D shows a stake  20  with the extension block  92  and the corresponding extension  90 . The extension block  92  and extension  90  are secured using pins  84  and corresponding lynch pins  86  to secure the pins  84 . 
     FIG. 7 is an end view of the extruded bunk  40 , which shows an internal wall or web  44  extending centrally across the bunk  40 . The web  44  transverses the interior of the bunk  40  from top to bottom. The web  44  extends the complete length of the interior of the bunk  40 . The lightweight bunk  40  is mounted in or on the bed of a truck or trailer  10 . The bunk  40  is manufactured using an extrusion method, from aluminum or other lightweight metals or materials. The bunk  40  may be molded of steel or other ferrous metals. The bunk  40  may have a solid interior resulting from the original extrusion or as a result of the addition of other lightweight strengthening materials added thereto. 
     In this example, the overall width of the bunk  40  is 3.00″, and the overall depth of the bunk  40  is 6.00″. The thickness of the walls is 0.29″, and the web  44  has a thickness of 0.29″. The web  44  is formed during the extrusion process, and extends the complete length of the interior of the extruded bunk  40 . The extruded bunk  40  has radiused corners  45 ,  47 . The radius of the inside corners  45  is 0.29″, and the radius of the outside corners  47  is 0.50″. The web  44 , along with the radiused corners  45 ,  47 , adds significant strength to the bunk  40 . It should be noted that the present invention is not limited to these particular dimensions. The extruded bunk  40  has a pocket on each end into which the aforementioned stake  20  is vertically inserted. 
     FIG. 8 shows an end view of an alternate embodiment of the bunk  40  of the present invention. The bunk  40  of FIG. 8 is a lightweight, extruded webbed bunk  40  with not only a first web  46  extending vertically, but also a second web  48  extending horizontally to further increase the dimensional stability and strength of the bunk  40 . 
     As shown in FIGS. 9A-9D, the bunks  40  may be extended through the use of extensions devices. FIG. 9A illustrates a bunk  40  with the extension block  52  welded into the end of the bunk  40  with the extension  50  to the bunk  40  immediately to the right. FIG. 9B illustrates the bunk  40  with the extension  50  located on the extension block  52 , and a pin  84  in position with a lynch pin  86  which will secure the pin  84 . FIG. 9C shows a bunk  40  in a horizontal position with an extension block  54  and a corresponding extension  50  immediately to the right. FIG. 9D illustrates the bunk  40  with the extension  50  added using the extension block  54 , and pins  84  in position and lynch pins  86  which secure the pins  84 . 
     FIG. 10 illustrates the bunk pocket  60  including a cutaway section allowing the viewer to see the lip molded into the bottom of the pocket which restrains the stake  20  from passing through the pocket. 
     The bunk pocket  60  is manufactured from aluminum or other lightweight metals or materials using a casting or injection molding method.  17 . The bunk pocket  60  may also be molded of steel or other ferrous metals. The bunk pocket  60  may also be molded of titanium or other non-ferrous metals or materials. The overall dimensions of the bunk pocket  60  are 5.25″×4.26″×8.0″. The bunk pocket  60  is welded to each end of the bunk  40 . Each bunk pocket  60  has an opening  62  on the top which measures approximately 3″×4″ into which an extruded stake  20  can be inserted. Depending on the height of the stake  20 , the total volumetric area of the vehicle or trailer  10  can be increased or decreased. 
     A thickened shoulder  64  is molded around the top of the bunk pocket  60  and is approximately 0.63″ thick. The shoulder  64  extends downwardly from the top of the bunk pocket  60  by about 1″ to assure the bunk pocket  60  can withstand the stress transferred to it as a result of the outward pressure placed on the stakes  20  by the load of logs  12  or other cargo. Also molded into the bunk pocket  60  is a lip at the bottom of the bunk pocket  60  that keeps the stake  20  from sliding through the bunk pocket  60 . The wall thickness in the area between the shoulder  64  and the lip  66  is about 0.31″, while the wall thickness including the lip  66  is about 0.69″ and extends up from the bottom of the bunk pocket  60  by about 0.38″. 
     FIG. 11 illustrates an alternate embodiment of the bunk pocket  60  including a cut-away section allowing the viewer to see the lip  66  molded into the bottom of the bunk pocket  60 . The lip  66  restrains the stake  20  from passing through the bunk pocket  60 . Also illustrated are a series of buttresses  68  and an increase in the wall thickness added to the bunk pocket  60  to further increase the dimensional stability and strength of the bunk pocket  60 . Although buttresses  68  are shown running vertically, they may also be positioned in a horizontal fashion running around the exterior of the bunk pocket  60 . 
     FIG. 12 illustrates a further embodiment of the bunk pocket  60  including a cut-away section allowing the viewer to see the lip  66  molded into the bottom of the bunk pocket  60 . The lip  66  restrains the stake  20  from passing through the bunk pocket  60 . The walls  70  of the entire bunk pocket  60  have an increased thickness over the entire bunk pocket  60 , thereby increasing the dimensional stability and strength of the bunk pocket  60 . 
     FIG. 13 illustrates a further embodiment of the bunk pocket  60  which includes a solid bottom  72  which restrains the stake  20  from passing through the bunk pocket  60 . A drain hole  74  is provided in the bottom  72  which allows water and debris to fall out the bottom of the bunk pocket  60 . The drain hole  74  is approximately 1.5″ in diameter. The solid bottom  72  increases the dimensional stability and strength of the bunk pocket  60  for supporting the stake  20  which is inserted in the bunk pocket  60 . 
     FIGS. 14A-14C illustrate the method of securing the stake  20  to the bunk pocket  60  of the bunk  40  through the use of a pin  84 . The pin  84  is secured after passing through the bund pocket  60  and the stake  20  with a lynch pin  86 . Once the stake  20  has been inserted into the bunk  40  and is resting in the bunk pocket  60 , the stake  20  is secured in the bunk pocket  60  by inserting a pin  84  having a diameter of ⅝″ through both the bunk pocket  60  and the stake  20  via a centered {fraction (13/16)}″ hole bored through the bunk pocket  60  and the hole in the stake  20  that is ¾″. The pin  84  is then secured in place by inserting a {fraction (3/16)}″ lynch pin  86  through a ¼″ hole, located approximately 5″ from the head of the pin  84 , and bored through the diameter of the pin  84 . The stakes  20  may also be permanently secured into bunk pockets  60  via welding or other permanent securing methods. 
     FIGS. 15 a  and  15   b  illustrate the stakes  20  being repositioned by an operator  18  standing on the ground  16 . Also illustrated is the repositioning of stakes  20  from the sides of the trailer  10  to the back of the trailer  10 , once again while the operator  18  remains on the ground  16 . 
     Typically with steel stakes  20 , the operator  18  must get up onto the bed of the truck or trailer  10  to move the stakes  20  due to their weight. This repositioning of the stakes  20  is necessary to accommodate logs  12  of a different length than the ones that comprised the previous load. Repositioning of the stakes  20  is necessary to accommodate logs  12  that will be loaded perpendicular to the length of the trailer  10  or truck as opposed to parallel to the length of the trailer  10  or truck, or visa-versa. Thus, stakes  20  must be moved from the side of the trailer  10  to the front and rear of the trailer  10 . Because of the extreme weight of steel stakes  20 , the operator  18  must get up on the bed of the trailer  10  to control the stake  20  by grasping it close to its center point. The aluminum stakes  20  afford the operator  18  the ability to change the position of the stakes  20  from the ground  16  without getting up on the bed of the truck or trailer  10  because, due to the reduced weight, control of the stake  20  may be maintained without grasping it near its center point. The reduced weight of the aluminum stakes  20  makes repositioning stakes  20  faster, safer and easier as the repositioning may be done from the ground  16 . 
     An analysis was performed by comparing the relative strength of current steel bunks and stakes to that of aluminum counterparts formed according to the present invention. A test load was developed using the known maximum payload of a trailer  10 , approximately 70,000 pounds. The current steel stakes, bunks and bunk pockets are made from a 50,000 psi yield strength material. The design is stable and very few failures were seen. Thus, if an aluminum bunk  40 , bunk pocket  60  and stake  20  could be made to be as strong as steel, they too should show similar stability under the 70,000 pound load. 
     The stake  20  modeled was made of 6061 T6 aluminum and had a cross section as shown in FIG.  4 . The stake  20  was tested individually verses its steel counterpart. The bunk  40  modeled in the test was made of 6061 T6 aluminum and had a cross-section as shown in FIG.  7 . The bunk  40  measured 3 inches by 6 inches, and had a ⅜ inch wall thickness. The bunk pocket  60  in the test was made of ⅜ inch thick 6061 T6 aluminum and had a shape as shown in FIG.  10 . 
     A first test was performed to determining the tensile strength. The stakes  20  and bunks  40  were modeled together for a realistic stress test. A load of 4,000 pounds was applied to the top side of the bunk  40 . The load was derived by using 70,000 pound payload divided by the 8 bunks  40  that would be on the trailer  10 . This number was then divided into uniform loads that would sit above the frame rails and on each side of the frame rails. The model is only of the bunk  40  from the inside of the frame rail to the outside of the trailer  10 . A 1,500 pound load was applied to the inside face of the stake  20 . This load simulates the force of the logs  12  wanting to roll off the pile and exerting force against the stake  20 . This load also simulates the force of the loader pushing the logs  12  down to situate them. 
     A second test was performed to determine the endurance The stakes  20  and bunks  40  were put through a test consisting of 500 million high stress loading cycles. This exceeds the normal number of stress cycles in the usual life of a stake  20  and a bunk  40 . The normal number of stress cycles in the life of a bunk  40  and stake  20  is 3,120,000 cycles. The following chart illustrates the calculations used to determine the number of stress cycles in the life of a stake  20  and bunk  40 : 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Operation 
                 No. of Stress Cycles 
                 Times Per Day 
               
               
                   
                   
               
             
             
               
                   
                 Loading 
                 40 
                 4 
               
               
                   
                 Hauling 
                 20 
                 4 
               
               
                   
                 Unloading 
                 40 
                 4 
               
               
                   
                   
               
             
          
         
       
     
     Total per day=400 
     Total per week (6-day work week)=2400 
     Total per year (52 weeks per year)=124,800 
     Total per life (25 years)=3,120,000 
     The number of high stress cycles is less than 500 million in the lifetime of this invention, and the minimum yield strength is higher than 20,000 psi. “The force applied to an element divided by the area to which the force is applied is known as stress. For example, if a 10″ by 10″ square column carries a 120,000 pound load, it&#39;s stress is calculated by dividing 120,000 by 100, which equals 1,200 pounds per square inch, abbreviated 1,200 psi. 
     The results of the load carrying tests reveal that the aluminum design is 25 percent stronger than the steel design. The 6061-T6 aluminum used in the second test has a yield strength of approximately 40,000 psi compared to steels rated 50,000 psi, which makes the aluminum 20 percent weaker than the steel counterpart. Although weaker than the steel in psi, the aluminum well exceeds the federal regulations on stakes. Stress plots generated revealed that the aluminum extrusion stakes  20  of this invention show stress levels lower than that of steel stakes. The steel has the initial advantage in terms of ultimate tensile strength (psi), but this invention has a fifty-four percent lower stress level, and it is twice as strong as a steel stake. 
     Radiused corners must carry their own weight plus the pressure of a load placed within the confines of the trailer  10  or truck. Because of the arch action of horizontal curvatures, the pressure of loads against the face of the stakes  20  is channeled to the sides of the stake  20  that are perpendicular to the load (see FIG. 4) and ultimately to the bunk  40  and bunk pocket  60 , into which the stake  20  is secured. Loads accumulate along vertical medians, and they become more and more compressed as they approach the radiused corners (see FIG.  4 ). As in the construction of arches, radiuses corners provide additional strength. This invention complies with the configuration of a monolithic structure, allowing for the reduction in the wall thickness of the extruded stake  20 , as loads, and the force of the load is distributed more evenly to the sides of the stake  20 . 
     The continuity of radiused corners allows such reduction of thickness by introducing actions along horizontal sections or parallels that prevent the sides of the stake  20  from being distorted. The parallels or walls of the stake  20  behave like the curvatures of an arch. Further, the additional member or centrally located web  24  allows the stake  20  to twist as a result of load stress to a greater extent, without failure of the stakes  20  structural integrity. The centrally located web  24  member adds additional strength and rigidity to the stake  20 . 
     The aluminum from which the stake  20 , bunk  40  and bunk pocket  60  is extruded affords greater corrosion resistance than similar ferrous or ferrous alloy materials, The aluminum and the corresponding resistance to corrosion affords the stakes  20 , bunks  40  and bunk pockets  60  a greater life span, particularly in locations where salt is used on road surfaces. 
     The aluminum composition and structural configuration of the stakes  20  affords persons who must insert and remove the stakes  20  greater ease and safety in handling the stakes  20  as a result of the decreased weight of the stake  20 . The aluminum stakes  20  afford the operator  18  the ability to change the position of the stakes  20  without getting up on the bed of the truck or trailer  10 . 
     The bunk pockets  60  are attached to the bunk  40  which is correspondingly integrated into a frame  14  of the trailer  10  or truck. The stakes  20  may be used alone without the aluminum bunk  40  or bunk pocket  60 , or along with either the bunk pocket  60  or the bunk  40 . 
     It is to be understood that the invention is not limited to the numerical, material, or structural configurations in the descriptions in the above embodiment. Further, the elements, stake  20 , bunk  40 , and bunk pockets  60  can be used individually or in combination with one another. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.