Skateboard Truck With Improved Axle Assembly

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

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

Not Applicable

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

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

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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

FIG. 1 is a front view of one form of the skateboard truck of the invention.

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.

FIG. 1B is an enlarged, cross-sectional view of one form of the axle of the skateboard truck of the invention.

FIG. 1C is an enlarged, cross-sectional view of an alternate form of axle of the skateboard truck of the invention.

FIG. 1D is an enlarged cross-sectional view taken along lines 1D-1D of FIG. 1.

FIG. 2A is a cross-sectional view of still another form of axle of the skateboard truck of the invention.

FIG. 2B is a cross-sectional view of yet another form of axle of the skateboard truck of the invention.

FIG. 2C is a cross-sectional view of still another form of axle of the skateboard truck of the invention.

FIG. 3 is a fragmentary, illustrative cross-sectional view illustrating the appearance of the device when no load force is applied to the device.

FIG. 3A is a greatly enlarged cross-sectional view of the area designated in FIG. 3 as 3A.

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.

FIG. 4A is a greatly enlarged cross-sectional view of the area designated in FIG. 4 as 4A.

FIG. 5 is a greatly enlarged, generally perspective, exploded view of one form of the hangar assembly of the invention.

FIG. 6 is an enlarged, generally perspective view of a typical prior art bushing.

FIG. 7 is an enlarged, generally perspective view of one form of the novel bushing of the present invention.

FIG. 7A is a side view of the tilt bushing shown in FIG. 7 as it appears under no load.

FIG. 7B is a greatly enlarged view of the area designated in FIG. 7A as 7B.

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.

FIG. 8A is a greatly enlarged view of the area designated in FIG. 8 as 8A.

FIG. 9 is a generally perspective view of yet another form of the skateboard truck as it appears when mounted on a structural member.

FIG. 9A is a greatly enlarged view of the area designated in FIG. 9 as 9A.

FIG. 10 is a generally perspective view of an alternate form of the base assembly of the skateboard truck.

FIG. 11 is a generally perspective view of still another form of the base assembly of the skateboard truck.

FIG. 12 is a generally perspective view of yet another form of the base assembly of the skateboard truck.

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

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).

Axle 21 is of the unique construction shown in FIG. 1B and includes a central portion 21a, a pair of end portions 21b, and a pair of intermediate portions 21c. Intermediate portions 21c 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 21a of a first diameter, a pair of end portions 21b of a second lesser diameter, and a pair of intermediate portions 21c 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 21a includes an inwardly curved recess 24.

As shown in FIGS. 1 and 1B, intermediate portions 21c of the axle 21 carry inside wheel bearings 32, while the threaded end portions 21b 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.

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 35a and 35b that are welded together at the parting line 35c. Axle 35 is of the unique construction shown in FIG. 1C and includes a central portion 36a, a pair of end portions 36b and a pair of intermediate portions 36c. Intermediate portions 36c here define the inner bearings of the axle, while end portions 36b 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 35a and 35b to form hollow segments 40 and by boring out the end portions of each of the first and second portions 35a and 35b to form hollow segments 41. Following the boring step, the first and second axle portions 35a and 35b 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 35d of a first diameter, a pair of end portions 35e of a second lesser diameter, and a pair of intermediate portions 35f of a third diameter that is greater than the second diameter but less than the first diameter. As before, intermediate portions 35f of the axle 35 carry inside wheel bearings 32, while the threaded end portions 35e 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 35f 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 35e, where less sheer forces are less, are of a second wall thickness, less than the first wall thickness.

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.

Referring now to FIGS. 2A, 2B and 2C, 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.

In forming the hanger assembly 20 of the invention, a selected one of axle 21, or axle 35, is cast into the hanger barrel 46a to form the construction illustrated in FIG. 1. As best seen in FIG. 1A, connected to the hanger barrel 46a and extending therefrom is a generally triangular shaped kingpin connector 46b to which the highly important kingpin assembly 18 is connected. The kingpin assembly 18 here comprises a connecting rod 39 having a trunk portion 39a and a head portion 39b. Connected to the trunk portion 39a of connecting rod 39 are first and second tilt-crush elastic bushings 48a and 48b. The function of these tilt-crush elastic bushings will be described in the paragraphs which follow.

As seen in FIG. 3, hanger assembly 20 also includes a central alignment leg 46c that projects in a transverse direction from barrel 46a. Alignment leg 46c, 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.

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.

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.

Considering now the function of the tilt-crush elastic bushings 48a and 48b 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 49a and 49b that receive bushings 48a and 48b 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 48b 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.

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 52ALT that define a plurality of circumferentially spaced cavities 54ALT (see also FIGS. 7A and 7B). With this novel construction, as load is applied to the bushing in the direction of the arrow 56ALT of FIG. 8, the upper tilt bushing will be encouraged to bulge into recessed cavities 54ALT and between the ribs 52ALT as indicated by the lines 58ALT, thereby encouraging movement, more readily absorbing shock, and significantly improving the ride quality of the truck (see also FIG. 8A).

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 46b (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 60a 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 46b can be adjusted by tightening and loosening the pair of lock nuts 60b.

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.

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.

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.

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.

Claims

1. A truck for a skateboard, scooter and the like, having a structural member, said truck comprising:

(a) a base assembly connected to the structural member;

(b) a kingpin assembly connected to said base assembly;

(c) a hanger assembly connected to said kingpin assembly, said hanger assembly including an axle having a central portion of a first diameter, a pair of end portions of a second lesser diameter and a pair of intermediate portions of a third diameter greater than said second diameter and less than said first diameter; and

(d) a pair of wheels rotatably mounted on said axle.

2. The truck as defined in claim 1 in which said axle has intermediate portions of a first wall thickness and end portions of a second, lesser wall thickness.

3. The truck as defined in claim 1 further including inside wheel bearings mounted on said intermediate portions of said axle.

4. The truck as defined in claim 1 further including outside wheel bearings mounted on said end portions of said axle.

5. The truck as defined in claim 1 in which said axle is formed by swaging a length of metal tubing.

6. The truck as defined in claim 1 in which said central portion of said axle is generally rectangular in cross-section.

7. The truck as defined in claim 1 in which said central portion of said axle is generally oval in cross-section.

8. The truck as defined in claim 1 in which said central portion of said axle is generally triangular in cross-section.

9. The truck as defined in claim 1 in which said kingpin assembly comprises a connecting rod having a trunk portion and a head portion and a tilt-crush elastic bushing connected to said trunk portion of said connecting rod.

10. The truck as defined in claim 9 in which said hanger assembly comprises a hanger barrel and a kingpin connector connected to said hanger barrel, said kingpin connector being provided with a pocket seat having a plurality of circumferentially spaced ribs that define a plurality of circumferentially spaced cavities, said pocket seat being so constructed and arranged to receive said tilt-crush elastic bushing.

11. A truck for a skateboard, scooter and the like, having a structural member, said truck comprising:

(a) a base assembly connected to the structural member;

(b) a kingpin assembly connected to said base assembly, said kingpin assembly comprising a connecting rod having a trunk portion and a head portion and a tilt-crush elastic bushing connected to said trunk portion of said connecting rod;

(c) a hanger assembly connected to said kingpin assembly, said hanger assembly comprising: (i) a hanger barrel; (ii) an axle carried by said hanger barrel; (iii) a kingpin connector connected to said hanger barrel, said kingpin connector being provided with a plurality of stop pins connected to and extending from said kingpin connector; and

(d) at least one wheel rotatably mounted on said axle.

12. The truck as defined in claim 11 in which said axle has a central portion of a first diameter, a pair of end portions of a second lesser diameter and a pair of intermediate portions of a third diameter greater than said second diameter and less than said first diameter.

13. The truck as defined in claim 11 in which said base assembly includes a base having a pivot cup and in which said hanger assembly further includes a central alignment leg receivable within said pivot cup.

14. The truck as defined in claim 11 further including a pocket seat having a plurality of circumferentially spaced ribs that define a plurality of circumferentially spaced cavities, said pocket seat being so constructed and arranged to receive said tilt-crush elastic bushing.

15. The truck as defined in claim 11 in which said kingpin assembly further includes a second tilt-crush elastic bushing connected to said trunk portion of said connecting rod.

16. A truck for a skateboard, scooter and the like, having a structural member, said truck comprising:

(a) a base assembly connected to the structural member, said base assembly including a base having a pivot cup;

(b) a kingpin assembly connected to said base assembly, said kingpin assembly comprising a connecting rod having a trunk portion and a head portion and first and second tilt-crush elastic bushings connected to said trunk portion of said connecting rod;

(c) a hanger assembly connected to said kingpin assembly, said hanger assembly comprising: (i) a hanger barrel; (ii) an axle carried by said hanger barrel, said axle having intermediate portions of a first wall thickness and end portions of a second, lesser wall thickness; (iii) a kingpin connector connected to said hanger barrel, said kingpin connector being provided with a pocket seat having a plurality of circumferentially spaced ribs that define a plurality of circumferentially spaced cavities, said pocket seat being so constructed and arranged to receive a selected one of said tilt-crush elastic bushing; and

(d) a pair of wheels rotatably mounted on said axle.

17. The truck as defined in claim 16 in which said hanger assembly further includes a central alignment leg receivable within said pivot cup of said base assembly.

18. The truck as defined in claim 15 further including a plurality of stop pins connected to and extending from said kingpin connector.

19. The truck as defined in claim 15 in which said hanger assembly further comprises a pair of cup washers carried by said connecting rod of said kingpin assembly, said pair of cup washers being so constructed and arranged to receive said first and second tilt-crush elastic bushings.

20. The truck as defined in claim 15 in which said central portion of said axle includes an inwardly curved recess.