Patent Abstract:
A skateboard or longboard truck comprises a hanger and a baseplate assembly. A redesigned hanger, a large ball pivot, a load-redirecting pivot cup, a tapered kingpin and other improvements give the hanger a high kingpin ratio and a high angle of mechanical advantage, thereby improving the performance and turning characteristics of the truck.

Full Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of our U.S. Provisional Application No. 61/903,790, filed Nov. 13, 2013, and entitled “Skateboard/Longboard Truck With Active Massive Ball Pivot Mechanism,” which is herein incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The field of the invention is skateboards and longboards, and more particularly, trucks for skateboards and longboards. 
       BACKGROUND 
       [0003]    Traditional skateboard truck assemblies accomplish the action of turning when the rider shifts his weight on the skateboard deck from neutral to either side of the skateboard&#39;s longitudinal axis. 
         [0004]    Consistent with  FIG. 1  a complete skateboard assembly consists of two skateboard trucks with four attached wheels that are attached to a skateboard deck. Each skateboard truck comprises a baseplate assembly, which is attached to the deck, and a hanger assembly on which the wheels are hung. 
         [0005]    As a rider leans the skateboard deck from side to side, the axle integral to the skateboard truck hanger assembly is forced to stay parallel to the ground as long as the weight of the rider forces the wheels to remain in contact with ground. Rotation of the skateboard deck around an axis parallel to the longitudinal centerline of the skateboard deck causes the skateboard truck hanger assemblies to rotate—while staying parallel to the ground—about other axes, resulting in a turning action transmitted through the skateboard truck assemblies. 
         [0006]    Furthermore, when the deck of a typical skateboard is rotated, it causes the hanger assembly to rotate about an axis between the center of the extreme end of the pivot and a point in the center of the hanger aperture coincident with the longitudinal centerline of the kingpin. This causes fore and aft movement of the hanger and the wheels attached to it relative to the neutral position of the trucks when the deck is evenly weighted and parallel to the ground. As the rider angles the deck, the wheels proximate to the weighted side that is angled toward the ground move toward the middle of the skateboard deck, and the wheels on the opposite side from the weighted edge of the deck move away from the middle of the skateboard deck toward the ends of the skateboard deck. The result is that the trucks allow the rider to turn the skateboard by converting the force created by the leaning of the skateboard deck into a controlled turning action. The turning action is accomplished by the fore and aft movement of the wheels attached to the skateboard trucks as they rotate on the kingpin which is oriented at an angle less than 90 degrees to the ground plane ( FIG. 8 ). 
       SUMMARY 
       [0007]    A skateboard or longboard truck is provided that comprises a hanger and a baseplate assembly. The hanger includes a structural axle-bearing member and a pivot extending out perpendicularly from the structural member, a bushing seat and kingpin aperture located between the structural member and the pivot. The hanger is oriented along a lateral axis and configured to support two wheels. The baseplate assembly has a base that mounts underneath a skateboard or longboard deck. The baseplate assembly also has a mounting flange configured to receive a kingpin to secure the hanger assembly to the baseplate assembly. 
         [0008]    In one aspect of the invention, the hanger is configured with an angle of mechanical advantage of at least twenty degrees, wherein the angle is defined by two lines: the first line runs between a center of the kingpin aperture coincident with a longitudinal center of the kingpin and the pivot&#39;s center of rotation, and a second line runs between an outermost contact point of the ball pivot with the pivot cup and an opposing outermost bearing surface of the bushing seat. 
         [0009]    In another aspect of the invention, a kingpin ratio, defined by a distance between a lateral axle centerline perpendicular to the kingpin and a kingpin longitudinal centerline, divided by a distance between a pivot center and the kingpin longitudinal center line, expressed as a percentage, is more than fifty-two percent. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The benefits, features, and advantages of the present invention will become better understood with regard to the following description, and accompanying drawings where: 
           [0011]      FIG. 1  is a perspective view of a complete skateboard or longboard assembly 
           [0012]      FIG. 2  is a perspective view of one embodiment of a skateboard or longboard truck according to the present invention. 
           [0013]      FIG. 3  is an exploded perspective view of one embodiment of a skateboard or longboard truck according to the present invention. 
           [0014]      FIG. 4  is a perspective view of a hanger assembly of the truck of  FIG. 2 . 
           [0015]      FIG. 5  is a perspective view of a baseplate assembly of the truck of  FIG. 2 , 
           [0016]      FIG. 6  is a top view of the hanger assembly of the skateboard truck assembly of  FIG. 2 , illustrating dimensions that factor into the kingpin ratio, the angle of mechanical advantage, and center of pressure. 
           [0017]      FIG. 7  is a side section view of the truck assembly of  FIG. 2 , which illustrates the kingpin and baseplate angles of the truck, dual axes of rotation, and pivot load transfer. 
           [0018]      FIG. 8  is a bottom view of the skateboard assembly of  FIG. 1 , illustrating the relation between deck angle and truck turning angle. 
           [0019]      FIG. 9  is a perspective view of the pivot cup of  FIG. 3 , 
           [0020]      FIG. 10  is top view of the pivot cup of  FIG. 3 , illustration the airgap. 
           [0021]      FIG. 11  is a perspective cut-away view of the pivot cup of  FIGS. 3 and 10 , illustrating the threaded airgap and cleaning grooves 
           [0022]      FIG. 12  is a side view of the pivot cup of  FIGS. 3 ,  10 , and  11 , showing the tolerance fin. 
           [0023]      FIG. 13  is a perspective view of the kingpin of  FIG. 3 . 
           [0024]      FIG. 14  is a top view of the kingpin of  FIG. 3 , illustrating the tapered section of the shaft. 
           [0025]      FIG. 15A  is a view of the hanger assembly of  FIG. 3  while articulated, as it would characteristically be if the skateboard or longboard deck were bearing a statically unbalanced load. 
           [0026]      FIG. 15B  is a detail view of the ball pivot and pivot cup of  FIG. 16A , showing the non-interference zone of the ball pivot and pivot cup. 
           [0027]      FIG. 16A  is a top view of a prior art hanger while articulated, as it would characteristically be if a skateboard or longboard deck to which it were coupled were bearing a statically unbalanced load. 
           [0028]      FIG. 16B  is a top detail view of the prior art pin pivot and pivot cup of  FIG. 16A , illustrating the interference zone of the pin pivot and pivot cup. 
           [0029]      FIG. 17  is a side view of the baseplate of  FIG. 3 , showing the tapered walls and kingpin support section. 
           [0030]      FIG. 18  is a sectional view of the hanger assembly along the line  1 - 1  of  FIG. 3  in the direction of the arrows, illustrating the bushing seat. 
           [0031]      FIG. 19A  is a top view of a prior art skateboard truck assembly with wheels mounted. 
           [0032]      FIG. 19B  is a detailed top view of a prior art skateboard truck assembly with wheels mounted showing the need for two axle washers to create the necessary separation between the outer bearing race and face of the structural member. 
           [0033]      FIG. 20A  is a top view of the skateboard truck assembly with wheels mounted. 
           [0034]      FIG. 20B  is a detailed top view of the skateboard truck assembly with wheels mounted showing that the integral bearing standoffs create the necessary separation between the outer bearing race and face of the structural member. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    The following description is presented to enable one of ordinary skill in the art to make and use the present invention as provided within the context of a particular application and its requirements. Various modifications to the preferred embodiment will, however, be apparent to one skilled in the art, and the general principles defined herein may be applied to other embodiments. Therefore, the present invention is not intended to be limited to the particular embodiments shown and described herein, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed. 
         [0036]    The invention relates to a mechanism known in general terms as a skateboard truck. A skateboard truck connects wheels to a skateboard or longboard deck allowing articulation of the wheels attached to the skateboard truck by application of the rider&#39;s weight to one side of the deck ( FIG. 8 ). Application of weight to the edge of the skateboard deck allows the skateboard to be turned as the articulation of the deck converts deck angle changes into fore and aft movement of wheels attached to the skateboard truck. The invention improves on prior art in multiple ways, including an improved functional geometry, improved structural design, improved constructability, improved maintainability, and improved durability resulting in smoother and more responsive or immediate turning performance. 
         [0037]    The skateboard truck is comprised of two major assemblies, the ball pivot hanger assembly and the baseplate assembly. The assemblies are mechanically joined together and retained by a kingpin washer, elastomeric bushings, and kingpin nut ( FIG. 1 ). 
         [0038]    The hanger assembly is comprised of the hanger body, axle, axle washers and axle nuts. The body of the hanger incorporates a structural member oriented along a lateral axis perpendicular to and distal from the ball pivot. An axle made of a dissimilar material passes through the beam section of the body parallel to the beam. Alternatively, the axle may be made of two segments that pass into but not through the beam. On each end of the axle or axles there is an axle nut and axle nut washer. The ball pivot may be an integral part of the hanger body or may be a separate attached component. The ball pivot is formed so that it may rotate in a similar sized pivot cup by at least about twenty degrees in any direction without making contact with the pivot cup wall ( FIG. 15 ). The ball pivot has a diameter that is preferably at least 13 mm in diameter. There is an aperture in the hanger assembly body through which a kingpin passes that is located between the axle or axles and the ball pivot. The aperture has two elastomeric bushing seats that are concentric with the aperture and centerline of the kingpin. The bushing seats are located above and below the aperture ( FIG. 3 ). 
         [0039]    The baseplate assembly is comprised of a baseplate body, pivot cup and a tapered kingpin ( FIG. 36 ). The baseplate body has a pivot cup cavity in its forward section into which a removable friction fit pivot cup is installed. There are holes drilled into both sides of the baseplate body that are used to provide a means of attachment for the baseplate to the skateboard deck using fasteners. 
         [0040]    The pivot cup that is installed in the baseplate cavity bore provides a load bearing surface for the hanger assembly ball pivot. The pivot cup is designed to transmit loads from the ball pivot to the side-walls of the baseplate pivot cup cavity. The outside surface of cylindrical section of the pivot cup includes retention fins or rings that provide for a friction fit allowing friction based retention of the pivot cup in the pivot cup cavity. The exterior bottom surface of the pivot cup is angled so that no surface is more than fifty degrees off a line running through the center of the pivot cup hole in the bottom of the pivot cup and the center of the hanger-body bushing aperture. The bottom of the pivot cup is more steeply angled than prior art to allow the cup to compress down and toward the center of the pivot cup cavity in the baseplate. The inside contours of the pivot cup include self-cleaning groves that are designed to remove dirt or debris from the ball pivot when the ball pivot rotates. In the center bottom of the pivot cup there is a hole that provides a void for the pivot cup to compress down and into the bottom of the baseplate pivot cup cavity. The hole in the bottom of the pivot cup is also is designed to collect debris as part of the pivot cup&#39;s self-cleaning function and if threaded to provide for a means of threaded mechanical extraction using a threaded shaft or the axle of the hanger assembly. 
         [0041]    There is a kingpin support structure on the rear of the baseplate body that contains a tapered bore-hole into which the tapered kingpin is installed. The kingpin is a separate component that is inserted into the baseplate&#39;s tapered kingpin bore hole as part of the overall baseplate assembly. The kingpin has a tapered section proximate to the end of the kingpin where the head is designed to prevent rotation. The section in the middle of the kingpin where elastomeric bushings are later installed is of constant diameter that is smaller than the maximum diameter of the kingpin proximate to the head. The end of the kingpin distal from the head of the kingpin has threads that engage a kingpin nut. The kingpin relies on an enlarging taper proximate to the head of the kingpin that matches the angle of taper found in the kingpin bore hole for its mechanical connection to the baseplate. The taper provides for kingpin retention and load transfer to the baseplate through the sidewalls of the tapered kingpin bore hole. Rotation of the tapered kingpin is prevented by trapping the head of the kingpin on the side of the kingpin bore hole that is distal from the side of the kingpin bore hole that is adjacent to the lower elastomeric bushing bearing surface. 
         [0042]    The ball pivot hanger assembly is installed in the baseplate assembly by first placing the lower elastomeric bushing on the kingpin in contact with the adjoining baseplate bearing surface. The second step is to concurrently insert the ball pivot on the hanger assembly into the baseplate pivot cup while lowering the hanger assembly over the kingpin until the lower bushing seat on the hanger assembly has fully engaged the lower elastomeric bushing. Next, the upper elastomeric bushing is placed over the kingpin and seated into the upper bushing seat of the ball pivot hanger assembly. A bushing washer is placed on top of the upper elastomeric bushing. Finally a kingpin nut is threaded onto the kingpin resulting in compression of the bushing washer and the elastomeric bushings. ( FIG. 1 ). 
         [0043]    When fully assembled, the hanger assembly is sandwiched on both sides of the kingpin aperture by two elastomeric bushings, a kingpin washer and kingpin nut in a manner that allows the rider to adjust the level of pressure on the elastomeric bushings to increase or decrease the level of force required to angle the skateboard deck. The functional assembly traps the ball pivot on the hanger assembly in intimate contact with the pivot cup in the baseplate so that the ball pivot hanger assembly can rotate without interference and transfer loads effectively into the side wall of the baseplate as the mechanism is rotated from side to side ( FIGS. 3 ,  38 ). 
         [0044]    The drawings, with the exception of those labeled “prior art,” illustrate an embodiment of a skateboard truck  10  comprising a ball pivot hanger  15 , a baseplate assembly  115 , a pivot cup  155 , a kingpin  210 , bushings  242  and  245 , and various fastening members, including washers  250 ,  36  and nuts  255 ,  37 . 
         [0045]    Geometry 
         [0046]    The skateboard truck  10  improves upon previous skateboard truck designs by changing the geometry and design of one or more key elements of the skateboard truck  10 . Several of these improvements contribute to a high level of mechanical advantage  295  and improved turning function. These improvements include a larger diameter ball pivot  65 , effective transfer of ball pivot loads  142  into the side of the pivot cup cavity  140 , precision bushing seats  40 , the physical form of the baseplate  115  and the hanger  15 , and a tapered kingpin  210 . The improvements, whether considered singly or more preferably in combination, improve riding performance, mechanical function, durability, constructability and maintainability. It should be understood that the invention encompasses not only the synergistic combination of these various improvements, but also sub-combinations and single ones of these improvements. 
         [0047]    Ball Pivot Hanger 
         [0048]      FIGS. 2-4 ,  6  and  20  illustrate one embodiment of a ball pivot hanger  15 . The ball pivot hanger  15  comprises a structural member  20 , an integral axle  30  (or a pair of axles  30  mounted in the ends of the beam  20 ), bushing seats  40 , and a ball pivot  65 . The structural member  20  has a form determined by the principles of a wide flange I-beam. Reliefs  28  strategically reduce the mass and weight of the hanger  15  with minimum impact on the hanger&#39;s  15  strength. The structural member  20  is oriented to span the widest direction of the hanger  15 . The integral axle  30 , or axles  30  if separate axles are utilized, optionally made of a dissimilar material, runs from one end of the beam  20  to the other protruding so as to provide a mounting location for skateboard wheels  325 . 
         [0049]    The ball pivot hanger  15  includes two axle bearing spacing steps or bosses  35  (e.g., machined features at opposite distal ends of the structural member  20 ). Each boss  35  creates a separation  31  between the axle bearing surface  32  and the face  33  of the structural member  20  within which the axle  30  is contained so as to provide a bearing standoff that eliminates the need for an axle washer  36  known as a speedring. The boss  35  supports the central race  34  of the bearing and prevents the outer race  39  from making contact with the adjoining structural member  20 . Alternatively, the structural member  20  that embraces the axle  30  (or pair of axles  30 ) includes two bearing standoffs  35  that separate a bearing surface  32  of the structural member  20  from a non-bearing surface of the face  33  of the structural member  20  that embraces the axle  30 . The standoff may also be an additional component that is attached to the structural member  20  or axle  30 . 
         [0050]    Concentric top and bottom bushing seats  40  extend outwardly from a midsection of the structural member  20  and provide a zero tolerance fit for elastomeric bushings  242 ,  245 . An aperture  45  formed through the centers of the bushing seats  40  receives a kingpin  210  to mount the hanger  15 , sandwiched between the two elastomeric bushings  242 ,  245  to the baseplate  115 . An aperture  45  in the hanger  15  between the ball pivot  65  and the axle  30  allows a kingpin  210  to pass through the hanger  15  to assemble the hanger  15  to the baseplate  115 . 
         [0051]    Ball pivot 
         [0052]      FIG. 15  illustrates one embodiment of a ball pivot  65  incorporated into a hanger  15 . The ball pivot  65  extends perpendicularly out from the midsection of the structural member  20  and axle  30  and is, in one embodiment, preferably cast, forged, or machined as an integral part of the hanger  15  ( FIG. 6 ). The ball pivot  65  located on the hanger  15  differs from other traditional pin pivot or ball designs due to its much larger diameter  75 , preferably at least 13 mm, and resulting larger bearing surface. The ball pivot&#39;s  65  larger surface area combined with the pivot cup  155  and baseplate  115  design allow for pivot loads  142  to be transferred into the side wall  147  and tapered cavity walls  145  of the baseplate pivot cup cavity  140  instead of the bottom of the pivot cavity  140  as is typical with prior art ( FIG. 16 ). The design of the ball pivot  65  transfers turning load from the ball pivot  65  to the side wall  160  of the pivot cup  155  at a point much closer to the kingpin  210  compared to the small diameter ball or pin pivots  85  of many other designs, that transfer load from the pivot  85  to or near the bottom  102  of the pivot cup  103  through the end  95  of the pivot  85  distal to the axle. The large diameter ball pivot hanger  15 , pivot cup design  155 , tapered kingpin  210  and baseplate  115  design act synergistically to achieve improved turning performance. 
         [0053]    The ball pivot  65  provides unrestricted movement when compared to prior art pin pivots  85  that are not designed to accommodate significant unrestricted rotation on two planes as the skateboard truck  320  is articulated. The ball pivot  65  provides unrestricted turning action within at least about ten degrees from a neutral center line  300  that passes through the center of rotation  70  and a point  60  coincident with the center of the kingpin aperture  45  and the longitudinal center  212  of the kingpin  210  ( FIGS. 7 ,  13 - 14 ). Unrestricted turning action within the non-interference area  80  ( FIG. 15 ) is achieved due to an absence of mechanical interference with the pivot cup side wall  160  or progressive resistance from the compression of an elastomeric pivot cup  100  as is common with prior art designs ( FIG. 16 ). This improvement also eliminates the stress and mechanical wear that takes place with many conventional pin pivot  85  designs when they make physical contact with the wall of the pivot cup or pivot cup cavity. The ball pivot  65  on the hanger  15  in conjunction with the pivot cup  155  is configured to provide constant low-friction intimate contact between the pivot cup  155  and the ball pivot  65  allowing the ball pivot  65  to pass its loads through the sidewalls  160  of the pivot cup  155  and then directly into the side wall  160  of the baseplate pivot cup cavity  140 . 
         [0054]    Pivot Cup 
         [0055]      FIGS. 9-12  illustrate one embodiment of a pivot cup  155 . The pivot cup  155  is installed in the baseplate pivot cup cavity  140 . The pivot cup  155  comprises an internal pivot-bearing surface area  165  defined by curved cylindrical interior sidewalls  160 , a cylindrical outer top surface  162 , a ramped outer bottom surface  170 , cleaning grooves or channels  180 , retention fins or rings  195 ,  200 , and a ramping tolerance fin  205 . The pivot cup  155  is formed with a bottom center hole or pocket  185  that is configured to avoid contact with a bottom surface area portion  165  of the ball pivot  65  of at least approximately 0.6 steradians. This causes pivot loads  177  to be transferred into the side wall  147  of the baseplate pivot cup cavity  140  instead of the bottom of the pivot cavity as is typical with prior art ( FIG. 16 ). 
         [0056]    The pivot cup  155  provides a load bearing low friction constant contact transfer surface between the ball pivot  65  and the baseplate pivot cup cavity side wall  147 . The pivot cup  115  may be composed of nylon, POM (acetyl), PU (Polyurethane) or other suitable low friction, bearing surface materials. The cylindrical outer top surface  162  of the pivot cup  155  contains fins or rings  195 ,  200 ,  205  designed to compensate for dimensional tolerance variations between the pivot cup  155  and the pivot cup cavity  140 . The fins  195  retain the pivot cup  155  in the pivot cup cavity  140  and prevent pivot cup  140  rotation. The pivot cup&#39;s outer bottom surface  170  is angled to match the bottom portion  145  of the baseplate pivot cup cavity  140  ( FIG. 7 ). This angle provides a ramping force toward the center of the pivot cup cavity  140  when the pivot cup  155  is pressed into the cavity  140 . The ramping force is present when the truck  10  is in use and loads are applied via the rider&#39;s weight through the ball pivot  65  on the hanger  15 . The ramping action is designed to center and compress the pivot cup  155  in the baseplate pivot cup cavity  140 . 
         [0057]    The interior sidewalls  160  of the pivot cup  155  contain grooves or channels  180  designed to provide a self-cleaning action relative to the surface of the ball pivot  65  as it rotates in the pivot cup  155  ( FIG. 10 ,  11 ). The pivot cup  155  contains a hole  185  in its center so that as the pivot cup  155  is driven into the pivot cup cavity  140  by the ramping action it can compress without interference inward toward the center of the pivot cup cavity  140 , ensuring intimate contact between the internal pivot-bearing surface area  165  of the pivot cup  155  and the ball pivot  65 . The center hole  185  in the bottom of the pivot cup  155  also serves to provide self-cleaning, debris retention and threaded mechanical extraction functions. The pivot cup&#39;s center hole  185  may be threaded, allowing mechanical extraction of the pivot cup  165  from the pivot cup cavity  140  using a threaded rod or hanger axle  30  ( FIG. 4 ). Prior art pivot cups are made of soft elastomeric material and do not incorporate self-cleaning, self-centering, tolerance absorbing components, a provision for mechanical removal using threaded tools, or steep ramping surfaces 
         [0058]    Baseplate 
         [0059]      FIGS. 5 ,  7  and  17  illustrate one embodiment of a baseplate  115 . The baseplate  115  comprises a flanged base  116 , a kingpin support structure  224 , and a pivot cup cavity bore  140 . The pivot cup cavity bore  140 , located at a forward section of the baseplate  115 , is drilled at angle parallel to the primary or first axis  300  of rotation of the hanger  15 . The top portion  147  of the pivot cup bore  140  is defined by cylindrically shaped walls. The bottom portion  145  of the pivot cup bore  140  is defined by conically shaped tapered cavity walls angled no more than fifty degrees off of the primary rotational axis  300 . Accordingly, the opening angle  149  formed by the tapered cavity walls is no greater than one hundred degrees. The steep tapering of the cavity walls use the force from the rider&#39;s weight that is applied via the ball pivot  65  to drive the pivot cup  155  into the angled bottom portion  145  of the pivot cup cavity bore  140 . The ramped outer bottom surface  170  of the pivot cup  140  is configured with angles that match the angle of the bottom portion  145  of the pivot cavity bore  140  and allows for pivot cup compression into the pivot cup cavity bore  140 . Compression of the pivot cup  155  aids in preserving the constant center of rotation  70  allowed for by the ball pivot  65 . 
         [0060]    Also unlike prior art, on the rear section of the baseplate  115  there is a section of the body through which a tapered borehole  211  provides a support structure for the tapered kingpin  210 . The diameter  214  of the kingpin bore  211  hole proximate to the bolt head  215  is larger than the bore diameter  213  distal to the bolt head  215  ( FIG. 17 ). The lower section  222  of the kingpin support structure  224  includes a channel  218  that is used to prevent rotation of the kingpin&#39;s head  215  when the kingpin nut  255  is tightened to adjust bushing  242 ,  245  tension. The upper section  223  of the kingpin bore hole  211  is designed to function as a seat for the lower elastomeric bushing  242 . The flanges  116  of the base extend along both sides of the baseplate  115 . The flanges  116  contain holes  117  that provide a means to use fasteners to attach the baseplate  115  to the skateboard deck  330  ( FIG. 5 ,  7 ,  17 ). 
         [0061]    Kingpin 
         [0062]      FIGS. 3 ,  7 , and  13 - 14  illustrate one embodiment of a tapered kingpin assembly  207 . The tapered kingpin assembly  207  comprises a tapered kingpin  210 , a kingpin bushing washer  250 , two elastic bushings  242 ,  245 , and a nut  255 . The tapered kingpin  210 , which comprises a head  215  connected to a shaft  220 , is used to connect the hanger  15  to the baseplate  115 . The tapered kingpin  210  is removable with no damage to the baseplate assembly  115  and achieves a zero clearance fit when tightened into a matching tapered baseplate kingpin borehole  211 . When tightened by the compression of the kingpin nut  255  against the kingpin bushing washer  250  and two elastomeric bushings  242 ,  245 , the kingpin  210  acts as a rigid and integral component of the baseplate  115 . This increased rigidity of the baseplate  115  and kingpin assembly  207  results in improved turning performance by eliminating rocking or working of the kingpin  210  back and forth in a traditional kingpin borehole. 
         [0063]    Prior art includes two primary styles of kingpins. Kingpins that were intended to be removable were based on a simple bolt design with dimensional tolerances that resulted in movement of the kingpin from side to side in the kingpin baseplate bore hole as the truck was subjected to turning actions. Alternatively kingpins used in some prior art skateboard trucks incorporated barbed or splined driven bolts that were driven into the kingpin borehole. The splined or barbed bolt design was not easily removable and the process of removal and reinstallation would frequently result in damage to the kingpin bore hole that would further allow the kingpin to work back and forth as the deck angle was changed. Both the traditional bolt and barbed or splined prior art kingpin designs resulted in degraded truck performance, constructability and or maintainability. 
         [0064]    The kingpin shaft  220  includes a middle tapered section  225 . The remaining one or more sections of the shaft including the threaded end  240  and the constant diameter, are untapered. The tapered portion  225  of the kingpin  210  is located along a portion of the shaft that, when assembled, makes contact with the tapered baseplate borehole  211 . The tapered portion  225  of the kingpin  210  is distal from the threaded end  240  of the kingpin  210  and proximate to the polygonal head  215 . The diameter  230  of the kingpin  210  gets progressively smaller as one travels the length of the tapered section  225  of the shaft  220  from the top end of the tapered section  225 , proximate to the polygonal head  215 , toward the bottom end of the tapered section  225 , relatively more proximate to the bolt threads  240 . The diameter  227  of the kingpin  210  is constant in the un-tapered sections  227  of the shaft  220  which are not designed to engage the baseplate tapered borehole  211 , including locations where the kingpin  210  passes through the elastomeric bushings  242 ,  245  ( FIG. 7 ,  13 ,  14 ). 
         [0065]    The tapered kingpin  210  can be inserted into the tapered baseplate bore hole  211  until the increasing diameter of tapered kingpin  210  exceeds the matching maximum tapered borehole diameter  213 ,  214 . The kingpin  210  seats in the tapered borehole  211  with an intimate, zero clearance fit because the kingpin  210  always tapers to a diameter  230  larger than the largest tapered kingpin bore diameter  213  in the baseplate  115 . The tapered shaft  225  of the kingpin  210  is designed retain the kingpin  210  with the head  215  of the kingpin  210  slightly out of contact with the side of the tapered baseplate borehole  130  that is opposite from the side  241  where the elastomeric bushings  242 ,  245  seat ( FIG. 7 ,  17 ,  13 ,  14 ). 
         [0066]    The tapered kingpin  210  and tapered kingpin bore hole  211  provide a precision zero clearance kingpin fit in the baseplate kingpin tapered bore hole  211  while allowing for easy removal without damage to the kingpin  210  or kingpin borehole  211 . Because the kingpin  210  is in intimate contact with the tapered sidewalls  226  of the baseplate  115 , the baseplate  115  and kingpin  210  act as one unit transmitting forces precisely and immediately from the changing deck angle  318  into the truck assembly  10  ( FIG. 7 ,  17 ,  13 ,  14 ). 
         [0067]    Center of Rotation 
         [0068]    The location of the center of rotation  70  of the ball pivot  65  ( FIG. 6 ) is different from prior art. The center of rotation  70  of the ball pivot  65  ( FIG. 6 ), and the center of rotation  95  of a conventional prior art pin pivot  85 , are both herein defined as a point within or upon the surface of the pivot  65 ,  80  that translates the least, with respect to the baseplate, as the pivot  65 ,  80  rotates within a similarly sized pivot cup  155 . The larger diameter ball pivot  65  combined with the pivot cup  155  and baseplate  115  designs move the center of rotation  70  closer to the center of the kingpin aperture than is found in prior art designs. The center of rotation  70  is in the geometric center of the ball pivot  65 . Prior art designs have pin or ball pivots that are typically less than 13 mm in diameter. The center of rotation  95  for prior art pin or ball pivots is the center of the pivot radius proximate to the end of the pivot. Due to the small pivot diameter and the use flexible low-durometer pivot cups (e.g., below  95   a  durometer), these prior art designs transfer load thru the end of the pivot by bearing on the bottom of pivot cup. In most cases the use of a small diameter pivot and an elastomeric pivot cup does not provide for a constant center rotation ( FIG. 6 ,  15 ,  16 ). 
         [0069]    Center of Pressure 
         [0070]    The center of pressure  83  ( FIG. 6 ) for the ball pivot  65  is the location on the ball pivot&#39;s face central to where the greatest load is transmitted through the walls of the pivot cup  155 . As a result of moving the center of rotation  70  of the ball pivot  65  back to a point equidistant from all sides of the ball pivot&#39;s  65  rotating sphere, the center of pressure  83  also moves back and to the side of the ball pivot  65  relative to traditional pin pivot or ball pivot designs  65 . When turning the truck  10 , the center of pressure  83  is applied against the side  147  of the pivot cup cavity  140  at a point that is significantly distal from the bottom of the pivot cup cavity  140 . The center of pressure for prior art pin or ball pivots, by contrast, is concentrated proximate to the bottom of the pivot cup cavity. 
         [0071]    Angle of Mechanical Advantage 
         [0072]    Various aspects of the invention contribute to the truck&#39;s high and consistent mechanical advantage  295  in translating and amplifying the force a rider exerts on the deck into a force that turns the truck ( FIG. 6 ). One influential contribution to the truck&#39;s mechanical advantage is the angle  295  between two lines, referred to herein as the “angle of mechanical advantage.” The first line is the primary rotational axis  300  that runs between the center  60  of the kingpin aperture  45  and the ball pivot&#39;s constant center of rotation  70  ( FIG. 7 ). The second line  297  runs between an outermost contact point  298  of the ball pivot  65  with the pivot cup  155  and the opposing outermost bearing surface  299  of the bushing seat  40  that retains the elastomeric bushing  242 ,  245  laterally in the hanger  15 . Stated another way, the angle of mechanical advantage  295  is approximately equal to an inverse tangent of the sum of the ball pivot radius and the kingpin bushing radius divided by the ball-pivot-center-to-kingpin-center distance. A higher angle of mechanical advantage  295 , one that is, for example, at least twenty and preferably at least twenty-five degrees, significantly improves the rider&#39;s ability to compress the elastomeric bushings  242 ,  245  and magnifies the turning action of the truck  10  when compared with prior art designs. Additionally, the higher level of mechanical advantage  295  allows the truck  10  to rotate on two planes concurrently. 
         [0073]    The proximity between the center of rotation  70  of the ball pivot  65  and the center  60  of the kingpin aperture  45 , the diameter  75  of the ball pivot  65 , the diameter  41  of the bushing seat  40 , and the lack of movement achieved by the tapered kingpin  210  all combine to influence the angle of mechanical advantage  295  and the overall effective leverage the rider achieves against the elastomeric bushings  242 ,  245 . A high mechanical advantage  295  without pivot cup  155  restriction also facilitates a more dynamic turning response characteristic. 
         [0074]    King Pin Ratio 
         [0075]    Another contribution to the truck&#39;s mechanical advantage is the kingpin ratio ( FIG. 6 ). The kingpin ratio  290  is defined by the distance  291  between the kingpin aperture center  60  and longitudinal axle centerline  270  divided by the distance  292  between the ball pivot center  70 , or the constant center of rotation  70  and the kingpin aperture center  60 . The hanger  15  has a kingpin ratio  291 , expressed as a percentage, of fifty-two percent or more. 
         [0076]    A higher percentage kingpin ratio, in addition to a high angle of mechanical advantage, contributes to the truck&#39;s greater mechanical advantage relative to prior art designs. 
         [0077]    Concurrent Rotation on Two Axis 
         [0078]    The ball pivot hanger  15  rotates concurrently around two axes  300 ,  305  ( FIG. 7 ). The first axis  300  is between the constant center of rotation  70  of the ball pivot  65  and the kingpin aperture center  60 . The second axis  305  is parallel to the longitudinal centerline  212  of the kingpin  210  and runs thru the constant center of rotation  70  of the ball pivot  65 . This second axis  305  allows the hanger  15  to shift from side to side relative to the kingpin  210  while concurrently rotating relative to the first axis  300  with no pivot cup  155  or pivot cup cavity interference  140 . To rotate around the second axis  305 , the bushings  242 ,  245  must be compressed parallel to the kingpin bore hole  211  and the hanger bushing seat retention wall  43 . Any change in deck angle results in both a vertical compression and horizontal compression of the bushings relative to the kingpin ( FIG. 7 ). 
         [0079]    Riding benefit of Design 
         [0080]    All of the forces that compress the bushings  242 ,  245  and result in the articulation of the hanger  15  are from the rider&#39;s weight. All of the rider&#39;s weight is supported by the four wheels  325  mounted on the two axles  30 . A larger distance  291  between the axle  30  and kingpin aperture center  210  in relation to the distance  292  from the kingpin aperture center  210  to the constant center of rotation  70  results in greater mechanical advantage. A greater mechanical advantage results in more leverage acting on the bushings  242 ,  245 . With more leverage on the bushings  242 ,  245 , the rider is able to more effectively rotate the hanger  15  around the first  300  and the second axes  305 . Because of this increased mechanical advantage  295 , the lack of pivot interference with the pivot cup  155  or baseplate pivot cup cavity  140 , and the ability to rotate the hanger  15  concurrently around two axes  300 ,  305 , immediate articulation is achieved resulting in improved turning performance. 
         [0081]    Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions and variations are possible and contemplated. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiments as a basis for designing or modifying other structures for carrying out the same purposes of the present invention without departing from the spirit and scope of the invention as defined by the appended claims.

Technology Classification (CPC): 0