Abstract:
A truck for use with skateboards and skate devices that includes a novel kingpin assembly that includes a novel axle assembly that is stronger, more durable and lighter than prior art axle assemblies. The truck also has an improved truck hanger that includes a specially designed pocket seat that encourages the tilt-crush bushing of the truck to deform into a plurality of recessed cavities formed in the pocket seat (or plurality of recessed cavities in a novel tilt-crush bushing), thereby more readily absorbing shock and improving the ride quality of the truck. The improved truck hanger also includes uniquely positioned stop pins that function to limit the rotational movement of the truck hanger on the tilt axis during turning maneuvers so as to prevent the wheels from contacting the bottom of the deck and possibly ejecting the rider.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This is a Non-Provisional Application claiming the benefit of co-pending Provisional Application No. 61/959,725 filed Aug. 29, 2013. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC  
       [0003]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    The present invention relates generally to skateboards and skate devices, including wheeled scooters. More particularly, the invention concerns a truck having a novel axle assembly that is stronger, more durable and lighter than prior art kingpin assemblies. The invention also concerns a truck having an improved truck hanger that includes a specially designed pocket seat that encourages the tilt-crush bushing of the truck to deform into a plurality of recessed cavities formed in the pocket seat thereby more readily absorbing shock and improving the ride quality of the truck. The improved truck hanger also includes uniquely positioned stop pins that function to limit the rotational movement of the truck hanger on the tilt axis during turning maneuvers so as to prevent the wheels from contacting the bottom of the deck and possibly ejecting the rider. 
       DESCRIPTION OF RELATED ART INCLUDING INFORMATION DISCLOSED UNDER 37 CFR 1.97 AND 1.98 
       [0006]    Skateboards of various designs having a pair of trucks in opposing orientation disposed under a structural member are well known in the art. The prior art trucks are typically fitted with a pair of wheels with steering being accomplished by the rider tilting the rider surface, thus pivoting the hangers on a tilt axis between 30 and 55 degrees, rotating axles and wheels in opposite directions, thus causing the board to turn. The conventional kingpin truck consists of a hanger that tilts on a kingpin assembly mounted approximately perpendicular to the tilt axis and extending through a central aperture of the hanger with the steel connecting rod forming the kingpin. The hanger has a central alignment leg projecting in a transverse direction from the axle that maintains the tilt axis and is received by a pivot cup in the mounting base plate. 
         [0007]    The thrust of the present invention is to solve the problems discussed in the preceding paragraphs by providing a uniquely designed truck that includes a novel axle assembly that is stronger, more durable, and lighter than prior art axle assemblies. The invention also embodies an improved truck hanger that includes a specially designed pocket seat that encourages the tilt-crush bushing of the truck to deform into a plurality of recessed cavities formed in the pocket seat, thereby more readily absorbing shock and improving the ride quality of the truck. The improved truck hanger also includes uniquely positioned stop pins that function to limit the rotational movement of the truck hanger on the tilt axis during turning maneuvers so as to prevent the wheels from contacting the bottom of the deck and possibly ejecting the rider. 
         [0008]    It is to be observed that the lighter a truck, the easier it is to transport and the more it becomes useful for accomplishing various types of tricks. Unfortunately however, with respect to prior art trucks, a lighter truck is a weaker truck. To reduce weight, some manufacturers have introduced axles with hollow center cavities. Though there is a weight savings, the hollow axle does not have the durability of a solid axle, since a tube of a given diameter and material has at best only about 80%-90% the sheer stress resistance of a solid bar of the same given diameter and material. When the skateboard drops off a ledge or lands hard during the performance of a trick, a very high sheer stress is applied through the wheels, then to the inner and outer wheel bearing and finally to the axle. These forces can yield the tubing wall causing it to buckle. Skateboard axles are in reality cantilever structures having a portion embedded into the hanger casting and end portions that are threaded to receive a nut that functions to retain the wheel bearings and wheel. The end portions project from the hanger casting so that most of the sheer stress is concentrated in the first ⅓ of the cantilever where the inside wheel bearing resides, while the distal end of the axle where the outer wheel bearing resides, bears significantly less stress. Yet, in prior art truck axles, the diameter and the thickness of the axle is the same at the proximal and distal ends of the cantilever. 
         [0009]    The prior art U.S. Publication issued to Shih, No. 2003/0137116, discloses a hanger having a hollow axle, of a constant size, that is cast into a hanger that is lighter than a solid axle of the same diameter. This is a trade-off, as both the hanger and the cantilevered axle have been weakened for a very modest weight savings. 
         [0010]    A conventional skateboard truck hanger is located by the kingpin between an upper and lower bushing having sockets recessed in the hanger to receive the bushings. The lower bushing bears the weight of the rider and is primarily responsible for shock absorption generated from rough roads through elastic deformation. The construction of bushing sockets of prior art hangers has been solid and the lower bushing is received in a pocket located proximate the bottom of the hanger. Since polyurethane distorts and does not compress, as a load is applied to the bushing, the only possible area for the bushing to flex is along the outer walls. Because prior art hanger seats are solid, distortion primarily occurs in the outside wall of the bushing, substantially limiting the shock absorption potential of the bushing. 
         [0011]    Unfortunately, the polyurethane as currently configured does not absorb shock adequately. Urethane does not compress in the same way the rubber bushing used decades-ago did, urethane reacts to applied load by distorting or bulging. With prior art truck hangers, since the seat pockets are solid, this distortion can only occur in the outside wall of the bushing, limiting the shock absorption potential. 
         [0012]    Understanding that the ride of previous art was not satisfactory, U.S. Pat. Nos. 6,367,819 and 6,474,666 issued to Anderson teach the use of additional lower bushings to help soften the ride. However, in doing so, additional undesirable height and weight is added to the truck assembly. Additionally, additional length is added to the kingpin, thereby increasing stress on the kingpin assembly. In sharp contradistinction, the skateboard truck of the present invention provides a novel construction that allows the skateboard to ride better while using the existing single lower bushing found in prior art. Accordingly, the skateboard truck of the present invention does not add any additional cost to the truck. 
         [0013]    U.S. Pat. No. 7,093,842 to Chemlar, discloses a means for limiting the rotation of the hanger when turning. However, in Chemlar, this means is positioned so close to the pivot axis that a severe leverage disadvantage results which is readily apparent during a hard turning maneuver or when landing a jump. 
       SUMMARY OF THE INVENTION 
       [0014]    It is an object of the present invention to provide a truck for use with skateboards and skate devices that includes a novel axle construction which comprises an axle that has greater wall thickness in areas of high stress and lesser wall thickness in areas of lower stress. 
         [0015]    Another object of the invention is to provide a kingpin assembly of the character described in the preceding paragraph in which the diameter of the axle at the inner bearing area is larger than the axle diameter at the outer bearing area. 
         [0016]    Another object of the invention is to provide an improved truck hanger that includes a specially designed pocket seat that encourages the tilt-crush bushing of the truck to deform into a plurality of recessed cavities formed in the pocket seat, thereby more readily absorbing shock and improving the ride quality of the truck. 
         [0017]    Another object of the invention is to provide a kingpin assembly of the character described that includes a novel tilt-crush bushing having a plurality of recessed cavities into which the bushing can deform when placed under load. 
         [0018]    Another object of the invention is to provide an improved truck hanger that includes stop means for limiting rotational movement of the truck hanger on the tilt axis during turning maneuvers so as to prevent the wheels from contacting the bottom of the deck and possibly ejecting the rider. 
         [0019]    Another object of the invention is to provide a truck that is durable, safe, and highly reliable in operation. 
     
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         [0020]      FIG. 1  is a front view of one form of the skateboard truck of the invention. 
           [0021]      FIG. 1A  is a generally perspective view, partly in cross-section, of the form of the skateboard truck shown in  FIG. 1  as it appears when mounted on a structural member. 
           [0022]      FIG. 1B  is an enlarged, cross-sectional view of one form of the axle of the skateboard truck of the invention. 
           [0023]      FIG. 1C  is an enlarged, cross-sectional view of an alternate form of axle of the skateboard truck of the invention. 
           [0024]      FIG. 1D  is an enlarged cross-sectional view taken along lines  1 D- 1 D of  FIG. 1 . 
           [0025]      FIG. 2A  is a cross-sectional view of still another form of axle of the skateboard truck of the invention. 
           [0026]      FIG. 2B  is a cross-sectional view of yet another form of axle of the skateboard truck of the invention. 
           [0027]      FIG. 2C  is a cross-sectional view of still another form of axle of the skateboard truck of the invention. 
           [0028]      FIG. 3  is a fragmentary, illustrative cross-sectional view illustrating the appearance of the device when no load force is applied to the device. 
           [0029]      FIG. 3A  is a greatly enlarged cross-sectional view of the area designated in  FIG. 3  as  3 A. 
           [0030]      FIG. 4  is a fragmentary, illustrative cross-sectional view similar to  FIG. 3  illustrating the direction of load force applied to the device and illustrating the manner of deformation of the tilt bushings. 
           [0031]      FIG. 4A  is a greatly enlarged cross-sectional view of the area designated in  FIG. 4  as  4 A. 
           [0032]      FIG. 5  is a greatly enlarged, generally perspective, exploded view of one form of the hangar assembly of the invention. 
           [0033]      FIG. 6  is an enlarged, generally perspective view of a typical prior art bushing. 
           [0034]      FIG. 7  is an enlarged, generally perspective view of one form of the novel bushing of the present invention. 
           [0035]      FIG. 7A  is a side view of the tilt bushing shown in  FIG. 7  as it appears under no load. 
           [0036]      FIG. 7B  is a greatly enlarged view of the area designated in  FIG. 7A  as  7 B. 
           [0037]      FIG. 8  is a side view of the tilt bushing shown in  FIG. 7  as it appears under load and illustrating the manner of deformation of the tilt bushing. 
           [0038]      FIG. 8A  is a greatly enlarged view of the area designated in  FIG. 8  as  8 A. 
           [0039]      FIG. 9  is a generally perspective view of yet another form of the skateboard truck as it appears when mounted on a structural member. 
           [0040]      FIG. 9A  is a greatly enlarged view of the area designated in  FIG. 9  as  9 A. 
           [0041]      FIG. 10  is a generally perspective view of an alternate form of the base assembly of the skateboard truck. 
           [0042]      FIG. 11  is a generally perspective view of still another form of the base assembly of the skateboard truck. 
           [0043]      FIG. 12  is a generally perspective view of yet another form of the base assembly of the skateboard truck. 
           [0044]      FIG. 12A  is a greatly enlarged, exploded view of the stop pin holding bracket of the assembly shown in  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0045]    Referring to the drawings and particularly to  FIGS. 1 and 1A , one form of the truck of the invention is there shown and generally designated by the numeral  12 . As will become clear from the description that follows, the truck of the invention is usable with a skateboard, a scooter, and like vehicles of the character having a structural member  15 , such as a deck upon which the truck can be mounted. Truck  12  here comprises a base assembly  17  that is connected to the structural member  15  and a kingpin assembly  18  that is connected to base assembly  17 . Truck  12  also includes a novel hanger assembly  20  that is interconnected with the kingpin assembly. Hanger assembly  20  here includes a transversely extending axle  21  to which a pair of wheels “W” is rotatably mounted in a conventional manner well known to those skilled in the art (only one wheel is shown in  FIGS. 1 and 1A  of the drawings). 
         [0046]    Axle  21  is of the unique construction shown in  FIG. 1B  and includes a central portion  21   a,  a pair of end portions  21   b,  and a pair of intermediate portions  21   c.  Intermediate portions  21   c  here define the inner bearings  22  of the axle. While the axle can be formed in various ways, it is preferably constructed by swaging a length of metal tubing to form an axle of the character shown in  FIG. 1B  having central portion  21   a  of a first diameter, a pair of end portions  21   b  of a second lesser diameter, and a pair of intermediate portions  21   c  of a third diameter that is greater than the second diameter but less than the first diameter. For a reason presently to be described, central portion  21   a  includes an inwardly curved recess  24 . 
         [0047]    As shown in  FIGS. 1 and 1B , intermediate portions  21   c  of the axle  21  carry inside wheel bearings  32 , while the threaded end portions  21   b  carry outside wheel bearings  33 . Bearings  32  and  33  support wheels “W” and conventional axle nuts  30  function to hold the bearings and wheels in place. 
         [0048]    Turning to  FIG. 1C , an alternate form of axle is there shown and generally designated by the numeral  35 . Axle  35 , which is constructed in a different manner than axle  21 , comprises first and second metal portions  35   a  and  35   b  that are welded together at the parting line  35   c.  Axle  35  is of the unique construction shown in  FIG. 1C  and includes a central portion  36   a,  a pair of end portions  36   b  and a pair of intermediate portions  36   c.  Intermediate portions  36   c  here define the inner bearings of the axle, while end portions  36   b  define the outer bearings of the axle. Axle  35  can be formed in various ways, but it is preferably constructed by boring out the central portions of each of the first and second portions  35   a  and  35   b  to form hollow segments  40  and by boring out the end portions of each of the first and second portions  35   a  and  35   b  to form hollow segments  41 . Following the boring step, the first and second axle portions  35   a  and  35   b  are welded together and the central portion is embossed to form inwardly curved recess  42  that accepts the kingpin assembly. As in the earlier described axle  21 , axle  35  has a central portion  35   d  of a first diameter, a pair of end portions  35   e  of a second lesser diameter, and a pair of intermediate portions  35   f  of a third diameter that is greater than the second diameter but less than the first diameter. As before, intermediate portions  35   f  of the axle  35  carry inside wheel bearings  32 , while the threaded end portions  35   e  carry outside wheel bearings  33 . Bearings  32  and  33  support wheels “W” and conventional axle nuts  30  function to hold the bearings and wheels in place. As indicated in  FIG. 1C , the wall thickness of the inside wheel bearings, or intermediate portions  35   f  where the sheer forces of an applied load are the greatest, are of a first wall thickness. On the other hand, the outside wheel bearings or end portions  35   e,  where less sheer forces are less, are of a second wall thickness, less than the first wall thickness. 
         [0049]    In one form of the invention, the axle protruding from the casting to receive a wheel begins as a larger diameter for receiving an inside wheel bearing where the sheer forces of an applied load are greatest, then reducing to a smaller standard diameter for the outside bearing where sheer forces are less.  FIG. 1D  illustrates the cross- sectional appearance of the casting and the axle that protrudes therefrom. 
         [0050]    Referring now to  FIGS. 2A ,  2 B and  2 C, a plurality of alternate forms of axle constructions are there shown. More particularly,  FIG. 2A  shows an axle construction in which the central portion of the axle is generally rectangular in cross-section,  FIG. 2B  shows an axle construction in which the central portion of the axle is generally oval in cross-section, and  FIG. 2C  shows an axle construction in which the central portion of the axle is generally triangular in cross-section. 
         [0051]    In forming the hanger assembly  20  of the invention, a selected one of axle  21 , or axle  35 , is cast into the hanger barrel  46   a  to form the construction illustrated in  FIG. 1 . As best seen in  FIG. 1A , connected to the hanger barrel  46   a  and extending therefrom is a generally triangular shaped kingpin connector  46   b  to which the highly important kingpin assembly  18  is connected. The kingpin assembly  18  here comprises a connecting rod  39  having a trunk portion  39   a  and a head portion  39   b.  Connected to the trunk portion  39   a  of connecting rod  39  are first and second tilt-crush elastic bushings  48   a  and  48   b.  The function of these tilt-crush elastic bushings will be described in the paragraphs which follow. 
         [0052]    As seen in  FIG. 3 , hanger assembly  20  also includes a central alignment leg  46   c  that projects in a transverse direction from barrel  46   a.  Alignment leg  46   c , the distal end of which is received in a pivot cup  47  that is formed in base assembly  17  ( FIG. 1A ), functions to maintain the tilt axis of the skateboard. 
         [0053]    The connecting rod  39  of the kingpin assembly  18  can be described in structural terms as a cantilevered beam with the fixed end being attached to the base plate member and a free end protruding outwardly therefrom. When a force is placed at the free end of the cantilevered beam, sheer stresses are unequally distributed along the length of the beam with the greatest magnitude of stress concentrated at the fixed point and the least amount of stress being located at the free end. 
         [0054]    Additionally, the fixed end of the connecting rod is subjected to substantial tensile stresses. For example, as the hanger tilts for steering, stress is applied to the fixed end of the connecting rod as the hanger pries the two tilt-crush bushings apart using the connecting rod as a fulcrum. The energy stored during this compression of the tilt-crush bushings returns the hanger back to a neutral steering position. 
         [0055]    Considering now the function of the tilt-crush elastic bushings  48   a  and  48   b  of the present invention, in a conventional prior art skateboard, the lower polyurethane bushing bears the weight of the rider and is primarily responsible for shock absorption generated from rough roads through elastic deformation. The construction of the bushing sockets of the prior art hangers is typically solid and the lower bushing seats in a pocket formed proximate the bottom of the hanger. Because polyurethane and urethane does not compress, but only distorts, as load is applied to the bushing, the only area possible for the bushing to flex is along the outer walls of the bushing, thereby limiting the shock absorption potential of the bushing. As best seen in  FIG. 5  of the drawings, the truck hanger of the present invention includes cup washers  49   a  and  49   b  that receive bushings  48   a  and  48   b  respectively. The truck hanger also includes the specially designed pocket seat  47  that comprises a plurality of circumferentially spaced ribs  52  that define a plurality of circumferentially spaced cavities  54 . With this novel construction, as load is applied to the lower tilt bushing  48   b  in the direction of the arrow  56  of  FIG. 4 , the lower tilt bushing will be encouraged to bulge into recessed cavities  54  and between the seat pocket ribs  52  as indicated by the lines  58 , thereby encouraging movement, more readily absorbing shock and significantly improving the ride quality of the truck. 
         [0056]    Referring to  FIG. 7 , this figure drawing illustrates an alternate form of lower bushing of the present invention, which is identified as 48ALT. Unlike the upper surface “U” of the prior art bearing shown in  FIG. 6  of the drawings, the upper surface of this bearing is provided with a plurality of circumferentially spaced ribs  52 ALT that define a plurality of circumferentially spaced cavities  54 ALT (see also  FIGS. 7A and 7B ). With this novel construction, as load is applied to the bushing in the direction of the arrow  56 ALT of  FIG. 8 , the upper tilt bushing will be encouraged to bulge into recessed cavities  54 ALT and between the ribs  52 ALT as indicated by the lines  58 ALT, thereby encouraging movement, more readily absorbing shock, and significantly improving the ride quality of the truck (see also  FIG. 8A ). 
         [0057]    Another novel feature of the hanger of the present invention is the provision of stop means for limiting the rotational movement of the hanger on the tilt axis during turning maneuvers so as to prevent the wheels “W” from contacting or biting into the bottom of the deck  15  and possibly ejecting the rider. This important stop means here comprises a plurality of stop pins  60  that are threadably connected to and extend from the kingpin connector  46   b  ( FIGS. 5 and 9 ). As illustrated in  FIGS. 6 and 9A , with this construction, as the hanger tilts on the tilt axis in the manner indicated by the arrow  61 , the distal ends  60   a  of the stop pins  60  will engage the base assembly  17  and prevent the wheels “W” from contacting the bottom of the deck  15 . The extent to which the stop pins  60  extend from kingpin connector  46   b  can be adjusted by tightening and loosening the pair of lock nuts  60   b.    
         [0058]    Turning to  FIG. 10 , an alternate form of the base assembly  63  of the skateboard truck is there shown. In this form of the invention, the stop pins  60  are mounted on a pair of generally angularly extending faces  64  so that the pins extend angularly outwardly from the base assembly. 
         [0059]    In  FIG. 11 , there shown is a generally perspective view of still another form of the base assembly of the skateboard truck  66  in which the stop pins  60  are mounted on a pair of outwardly-extending ears  67  formed on the base assembly. 
         [0060]    Turning to  FIG. 12 , yet another form of the base assembly of the skateboard truck  70  is shown in which the stop pins are mounted on a holding bracket  72  which, in turn, is mounted proximate the upper portion of the base assembly.  FIG. 12A  is an enlarged, exploded view of the stop pin holding bracket  72  of the assembly shown in  FIG. 9 , showing the manner in which the stop pins are threadably interconnected with a holding bracket. 
         [0061]    Having now described the invention in detail in accordance with the requirements of the patent statutes, those skilled in this art will have no difficulty in making changes and modifications in the individual parts or their relative assembly in order to meet specific requirements or conditions. Such changes and modifications may be made without departing from the scope and spirit of the invention, as set forth in the following claims.