FIELD OF THE INVENTION

[0001] The present invention relates to an improved truck for a rideable vehicle, such as a skateboard. More particularly, the present invention relates to a truck having a supported axle that pivots independently around two axes where one axis can be releasably locked to provide dual modalities of use as either a conventional skateboard truck or a more

manoeuvrable caster truck all while utilising conventional skateboard bushings and pivot cups to reduce manufacturing cost and improve mechanical reliability.

BACKGROUND OF THE INVENTION

[0002] Conventional skateboards utilise steering mechanisms known as trucks. Trucks illustrative of those used in skateboards are shown in U.S. Pat. No. 2,763,490 entitled "Roller Skate" issued to Crone on Sep. 18, 1956, and U.S. Pat. No. 3,945,655 entitled "Brake for Skateboard and the Like" issued to Banks, et al. on Mar. 23, 1976. Typically trucks are mounted at the front and rear ends of an elongated skateboard deck where each truck includes a pair of wheels mounted at opposite ends of a supported axle. Trucks provide the steering mechanism for skateboards whereby lateral tilting of the skateboard deck opposably twists the axles causing the skateboard to turn. The trucks also resist lateral tilting of the deck by means of spring-loaded resilient linkages, commonly urethane bushings that stabilise the skateboard, returning the skateboard deck to its normal horizontal position when a turn is completed. This lateral stability is crucial to the useful operation of a skateboard.

[0003] Conventional skateboard trucks sacrifice their ability to turn for greater lateral stability, becoming stiff and unresponsive when tightened sufficiently to be stable at higher speeds. Conversely, loosening the trucks so the board can turn easily makes it dangerously wobbly. Furthermore, even in optimal conditions, the rate of turn provided by conventional skateboard trucks is limited. [0004] A popular and beneficial use of skateboards is to practice surfing and snowboarding manoeuvres. However, the turning circle of conventional skateboard trucks is too limited for this purpose. Previous attempts have been made to design a skateboard truck with increased manoeuvrability. One method utilising a trailing caster which provides the truck with a second axis of rotation that improves its turning radius is described in U.S. Pat. No. 5,522,620 entitled "Truck for a rideable vehicle, such as a skateboard" issued to Pracas on June 4, 1996. Another method which betters this 'caster truck' method by improving the steering geometry of the rotational axes is described in U.S. Pat. No. 6,793,224 entitled "Truck for skateboards" issued to Stratton on Sep. 21, 2004. However, both of these caster truck methods place substantial canter-leaver mechanical stress on the pivot bolts that connect the caster arm to the baseplate which is prone to failure. Additionally the caster truck embodiments described in these methods use specialised components including thrust bearings and adjustable springs which are costly to manufacture and susceptible to water and dirt ingress, which damages the mechanism causing premature failure. Skateboards with caster trucks have the disadvantages of being less stable at high speeds and being generally more difficult than conventional trucks for beginners to ride.

[0005] Another method for a skateboard truck with increased manoeuvrability featuring two stacked axes which incorporates the bushings and pivot cups used in conventional skateboard trucks is described in U.S. Pat. No. 7,150,460 entitled "Skateboard truck" issued to Williams on Dec. 19, 2006. However, while incorporating conventional skateboard bushings and pivot cups improves mechanical reliability, the near parallel rotational axes described in this method has the shortcoming of reduced lateral stability compared to a conventional skateboard truck.

[0006] It is an object of the present invention to provide an improved skateboard truck which ameliorates the disadvantages and shortcomings described above, or which at least provides the public with a useful choice. SUMMARY OF THE INVENTION

[0007] According to the present invention, there is provided an improved skateboard truck which pivots about two axes where a sliding lock is used to disable movement about the first axes so the truck functions in one of two modes, as either a conventional skateboard truck with adjustable lateral stability or as a caster truck with enhanced turning ability, all while utilising conventional skateboard bushings and pivot cups to reduce manufacturing cost and improve mechanical reliability.

[0008] Generally speaking, a skateboard is comprised of an elongated deck with a pair of trucks attached underneath. The improved skateboard truck is preferably attached to the front of the skateboard deck, while a conventional skateboard truck is fastened to the rear. The improved skateboard truck according to this invention comprises an assemblage of a baseplate, caster arm, a hanger supporting a transverse axle and a releasable locking mechanism. The baseplate includes a pivot pin receiving hole, a supporting bracket with a kingpin bolt receiving hole, a sliding lock cradle receiving aperture, and a longitudinal slot with a small spring loaded bolt receiving hole.

[0009] The caster arm with a pivot pin sheathed within a pivot cup mates with the pivot pin receiving hole in the baseplate. The caster arm includes a mounting portion with an oval shaped through-hole. First and second bushings are positioned on either side of the caster arm mounting portion. First and second washers are positioned against respective outer ends of the bushings. A kingpin bolt passes through the washers, bushings, and the oval shaped hole for mating with the kingpin bolt receiving hole on the support bracket of the baseplate. The caster arm carried by the baseplate by means of the pivot pin and bushings is rotatable relative to the baseplate about a first axis. The resilient linkage of the bushings pressed by the kingpin bolt against the mounting portion of the caster arm restricts rotational motion of the caster arm and biases the caster arm towards a centre position aligned with the skateboard's direction of movement. The caster arm includes a first horizontal bracket with a pivot pin receiving hole and a second horizontal bracket with a kingpin bolt receiving hole. [0010] The hanger supporting an axle having a pair of wheels mounted at opposite ends thereof has a pivot pin sheathed within a pivot cup that mates with the pivot pin receiving hole on the first horizontal bracket of the caster arm. The hanger includes a body portion with an oversized through-hole. Third and fourth bushings are positioned on either side of the hanger body portion. Third and fourth washers are positioned against respective outer ends of the bushings. A kingpin bolt passes through the washers, bushings, and the oversized hole for mating with the kingpin bolt receiving hole on the second horizontal bracket of the caster arm. The hanger carried by the caster arm via the pivot pin and bushings is rotatable relative to the caster arm about a second axis. The resilient linkage of the bushings pressed by the kingpin bolt against the body portion of the hanger restricts rotational motion of the hanger relative to the caster arm and biases the hanger towards a centre position such that the supported axle is horizontal to the skateboard's direction of movement.

[0011] A sliding lock comprised of a cradle and an elongated slide member are intercoupled with the baseplate such that the cradle is positioned inside the baseplate cradle receiving aperture and the elongated slide member is positioned inside baseplate longitudinal slot for relative longitudinal sliding between retracted and extended positions. In said retracted position the cradle sits clear of the caster arm and the caster arm is rotatable. In said extended position the sides of the cradle are adjacent to the sides of the caster arm such that the side portions of the cradle are in substantial contact with the sides of the first horizontal bracket of the caster arm and the cradle is laterally supported by the sides of the cradle receiving aperture of the baseplate preventing the caster arm from rotating. The elongated slide member of the slide lock includes a first and second aperture with a narrow open slot running between them.

In said retracted position the first aperture of the elongated slide member centre aligns with the spring loaded bolt receiving hole of the baseplate. In said extended position the second aperture of the elongated slide member centre aligns with the spring loaded bolt receiving hole of the baseplate. A small spring loaded bolt with a round head affixed to the bolt receiving hole of the baseplate operatively latches the sliding lock in either the retracted or extended position when the round head of the bolt mates with the respective first and second apertures of the elongated slide member. When the sliding lock is moved between the retracted and extended positions the spring loaded bolt is depressed so the round head of the bolt clears the first and second apertures while the shank of the bolt passes through the narrow slot between the apertures. When the sliding lock reaches the retracted or extended positions the spring snaps the round head of the bolt back into the respective aperture latching the sliding lock.

[0012] In a sense the present invention contemplates the provision of a skateboard truck comprising a caster arm adapted to be pivotally attached with resilient bushings operatively connected to a raised bracket, raised relative to the underside of a skateboard deck having a first skateboard truck pivot axis; an axle with provision for wheels to be attached at opposite ends thereof supported by a cross member adapted to be pivotally attached with resilient bushings operatively connected to the caster arm having a second skateboard truck pivot axis; said caster arm and cross member being ganged together to provide independently adjustable pivoting of the skateboard truck about two axes of freedom; and a releasable locking means to prevent said caster arm from pivoting about the first pivot axis by said locking means to optionally provide conventional pivoting of the skateboard truck about a single axis.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an exploded perspective view of the improved skateboard truck of the present invention;

FIG. 2 is a perspective view of the baseplate of the truck in FIG. 1;

FIG. 3 is a perspective view of the sliding lock of the truck in FIG. 1;

FIG. 4 is a perspective view of the caster arm of the truck in FIG. 1;

FIG. 5 is a perspective view of the hanger of the truck in FIG. 1;

FIG. 6 is a cross section view of the truck in FIG. 1;

FIG. 7A is a bottom on view of the truck in FIG. 1 mounted on then underside of a skateboard deck with the sliding lock in the retracted position and showing pivoting of the caster arm and hanger; FIG. 7B is a bottom on view of the truck in FIG. 1 mounted on then underside of a skateboard deck with the sliding lock in the extended position and showing pivoting of the hanger only;

DESCRIPTION OF EMBODIMENTS

[0013] In a preferred embodiment of the invention, there is provided an improved skateboard truck 10 having first 90 and second 92 axes of rotation. As shown in FIG. 1, the truck 10 comprises a baseplate 12, a caster arm 14, a hanger 16 and a sliding lock 18. The baseplate 12, caster arm 14, hanger 16 and sliding lock 18 can be of any suitable construction and made of any suitable material. In a preferred embodiment, the baseplate 12, caster arm 14, and hanger 16 are cast in A356 aircraft grade aluminium and heat treated to T6 and the sliding lock 18 is injection moulded in glass reinforced nylon plastic. In alternative embodiments the baseplate 12, caster arm 14, hanger 16 and sliding lock 18 may be cast or forged of any formable high strength metal or plastic.

[0014] Referring to FIG. 2, the baseplate 12 comprises a casting forming a base 20, a pivot platform 22, a support bracket 24, a cradle receiving aperture 26 and a longitudinal slot 28. The base 20 is a substantially rectangular plate having a finite thickness, for example 6 mm, and a plurality of apertures 40 suitably configured for mounting the baseplate 12 onto the underside of a skateboard deck. The support bracket 24 braced by side walls 30 projects outwards from one end of the base 20. The support bracket 24 includes a bushing mating surface 32 preferably angled at seventy-five degrees relative to the base 20 and includes a kingpin bolt receiving hole 34 therein. The pivot platform 22 is positioned between the side walls 30 and adjacent to the support bracket 24. The pivot platform 22 is integral with the support bracket 24 and projects outwards from the base 20 at a preferable relative angle of fifteen degrees and includes a pivot pin receiving hole 36 therein. The cradle receiving aperture 26 is a substantially rectangular opening in the base 20 positioned adjacent to the pivot platform 22. At opposite ends of the base 20 to the support bracket 24 a longitudinal slot 28 extends from the cradle receiving aperture 26 to the outside edge of the base 20. The longitudinal slot 28 includes a circular opening 38 for receiving a spring-loaded bolt. [0015] Referring to FIG. 3, the sliding lock 18 comprises a substantially U shaped cradle

44 including side portions 45 with transversely projecting shoulders 46 and includes a curved notch 47 on one side. An elongated slide member 48 extends laterally from the opposite side of the cradle 44 to the curved notch 47. The elongated slide member 48 includes a first 50 and second 52 circular aperture with a narrow open slot 54 running between the respective apertures 50, 52.

[0016] Referring to FIG. 4, the caster arm 14 comprises a casting forming a mounting portion 56 with an oval shaped through hole 58 centrally located between first 60 and second 62 bushing mounting surfaces. A pivot pin 64 projects laterally from one end of the mounting portion 56. Adjacent to the pivot pin 64, a first horizontal bracket 66 projects outwards from the mounting portion 56 and includes a pivot platform 68. The pivot platform 68 is preferably angled at sixty-five degrees relative to the mounting portion 56 and includes a pivot pin receiving hole 70 therein. A second horizontal bracket 72 projects outwards from the opposite end of the mounting portion 56 and includes a bushing mating surface 74. The bushing mating surface 74 is preferably angled at twenty-five degrees relative to the mounting portion 56 and includes a kingpin receiving hole 76 therein.

[0017] Referring to FIG. 5, the hanger 16 comprises a casting forming a body portion 78 with an oversized through hole 80 centrally located between first 82 and second 84 bushing mounting surfaces. A transverse cross member 85 extends outward in opposite directions from one end of the body portion 78. An axle rod 88 extends from end portions 87 of the cross member 85 suitable for mounting skateboard wheels 94 (See FIG. 6) on the axle threaded ends 89. A pivot pin 86 projects laterally from a central region of the body portion 78 opposite to the cross member 85. The preceding description of the hanger 16, which is a conventional skateboard part is provided by way of information as it does not, in itself, form part of the present invention. As would be recognised by one skilled in the art, the construction of the hanger can be modified as desired.

[0018] Referring to FIGS. 1 and 6, now consider the interconnection of the baseplate

12, caster arm 14, hanger 16 and sliding lock 18 described above. The caster arm 14 with pivot pin 64 sheathed within a pivot cup 108 mates with the pivot pin receiving hole 36 of the baseplate 12. A first resilient bushing 100 is circumferentially mounted on the first bushing mounting surface 60 and a second resilient bushing 102 is circumferentially mounted on the second bushing mounting surface 62 of the caster arm 14. First 104 and second 106 washers are positioned against respective outer ends of the bushings 100, 102. A first kingpin bolt 96 passes through the receiving hole 34 of the support bracket 24, the first washer 104 and bushing 100, the oval shaped through hole 58 of the caster arm 14, the second bushing 102 and washer 106, against which it is retained and adjustably tensioned by a first kingpin lock nut 98. The caster 14 arm carried by the baseplate 12 by means of the pivot pin 64 and bushings 100, 102 is rotatable relative to the baseplate 12 about a first axis 90.

[0019] The hanger 16 with pivot pin 86 sheathed within a pivot cup 118 mates with the pivot pin receiving hole 70 of the caster arm 14. A third resilient bushing 110 is

circumferentially mounted on the first bushing mounting surface 82 and a fourth resilient bushing 112 is circumferentially mounted on the second bushing mounting surface 84 of the hanger 16. Third 114 and fourth 116 washers are positioned against respective outer ends of the bushings 110, 112. A second kingpin bolt 120 passes through the receiving hole 76 of the second horizontal bracket 72 of the caster arm 14, the third washer 114 and bushing 110, the oversized through hole 80 of the hanger 16, the forth bushing 112 and washer 116, against which it is retained and adjustably tensioned by a second kingpin lock nut 98. The hanger 16 carried by the caster arm 14 by means of the pivot pin 86 and bushings 110, 112 is rotatable relative to the caster arm 14 about a second axis 92.

[0020] The sliding lock 18 and baseplate 12 are slidably intercoupled by means of the cradle 44 being positioned inside the receiving aperture 26 of the baseplate 12 with the shoulders 46 of the sliding lock 18 supported by the sides 42 of the baseplate 12 aperture 26 and the elongated slide member 48 of the sliding lock 18 positioned inside the longitudinal slot 28 of the baseplate 12. A round headed bolt 124 passes through the receiving hole 38 of the baseplate 12 and a compression spring 126 is held in place by a suitably tensioned lock nut 128. Relative longitudinal movement of the sliding lock 18 cradle 44 inside the baseplate 12 receiving aperture 26 is latched by means of the round head 130 of the bolt 124 mating with the circular first 50 and second 52 apertures of the slide member 48. Depressing the nut 128 end of the bolt 124 compresses the spring 126 forcing the round head 130 to clear the circular apertures 50, 52 allowing the bolt shank 132 to pass through the interconnecting slot 54 allowing the sliding lock 18 to move between retracted and extended positions. In said extended position the side portions 45 of the cradle 44 are in substantial contact with the sides of the first horizontal bracket 66 of the caster arm 14 and the cradle 44 is laterally supported by the sides 42 of the baseplate 12 aperture 26 preventing the caster arm 14 from rotating about the first axis 90. In said retracted position the cradle 44 with curved notch 47 sits clear of the caster arm 14 and the caster arm 14 is free to rotate about the first axis 90. As would be recognised by one skilled in the art, the construction of the sliding lock and latching mechanism can be modified as desired.

[0021] Considering now the operation of the improved skateboard truck 10 described above, the resilient linkage of the first 100 and second 102 bushings pressed by the first kingpin bolt 96 and nut 98 against the mounting surfaces 60, 62 of the caster arm 14 and the mating surface 32 of the baseplate 12 support bracket 24 restricts rotational motion of the caster arm 14 about the first axis 90 and biases the caster arm 14 towards a centre position. The resilient linkage of the third 110 and fourth 112 bushings pressed by the second kingpin bolt 120 and nut 122 against the mounting surfaces 82, 84 of the hanger 16 and the mating surface 74 of the caster arm 14 second horizontal bracket 72 restricts rotational motion of the hanger 16 about the second axis 92 and biases the hanger 16 towards a centre position.

[0022] A user may adjust the compression of the bushings 100, 102, 110, 112 against the mounting surfaces 60, 62, 82, 84, by tightening or loosening the kingpin nuts 98, 122, which in turn, limits the rotational movement of the caster arm 14 and hanger 16. Thus, a beginner can tighten the kingpin nuts 98, 122, so the skateboard becomes pivotally restricted and more stable, whereas an advanced rider, can loosen the kingpin nuts 98, 122, so the skateboard becomes pivotally looser and more manoeuvrable.

[0023] Referring to FIG. 7A, in use the improved skateboard truck 10 is preferably attached to the front underside of the skateboard deck 93 such that the horizontal brackets 66 (See Fig. 1), 72 of the caster arm 14 extend rearward, with a conventional skateboard truck 138 fastened to the rear of said deck 93. With the sliding lock 18 in the retracted position 134 described above, the caster arm 14 is free to rotate. In this configuration, the truck 10 converts lateral tilting of the skateboard deck 93 into substantially more than conventional 138 turning of the hanger 16 and wheels 94. The resilient bushings 100, 102, 110, 112 (See FIG. 1) resist the lateral tilting of the deck 93, causing the truck 10 to restore the wheels 94 to their centre position. Analogous to the caster described in U.S. Pat. No. 1,809,609 entitled "Caster" issued to Turner on Sep. 6, 1931, where the wheel trails behind the pivot axis, the forward movement of the skateboard also tends to align the caster arm 14 with the direction of movement. Thus, the caster arm 14 acts to automatically centre, or self correct itself, providing additional stability to the tuck 10 which counteracts its tendency for increased turning sensitivity.

[0024] Referring to FIG. 7B, with the sliding lock 18 in the extended position 136 described above, the caster arm 14 is prevented from rotational movement. In this

configuration, the truck 10 converts lateral tilting of the skateboard deck 93 into conventional 138 turning of the hanger 16 and wheels 94 providing increased lateral stability to the deck 93 allowing the skateboard to be less sensitive to turning and able to be ridden at higher speeds with increased control and steadiness.

[0025] Although the foregoing description is specific, it should not be considered as a limitation of scope, but only as an example of the present invention. Obvious modifications to the preferred embodiment, set forth above, could be readily made by those skilled in the art without meaningfully departing from the principal, spirit and scope of this invention.