Note: Descriptions are shown in the official language in which they were submitted.
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FIELD DF THE INDENTION
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This invention relates to skateboards.
BACKGROUND TO THE INDENTION
Conventional skateboards consist of a substantially rigid
board which carries two spaced wheel-sets or trucks which
are fixed to its underside with the wheels of the
wheel-sets lined on a common track. The wheels of each
wheel-set, on the more elaborate boards, are very slightly
steerable through an offset suspension system with the
skater steering the board by shifting his feet on and his
body position above the board so that the centre of
gravity of his weight may be used to vary the adhesion of
the wheels on a common wheel-set with the road surface.
U:S. Patent Nos. 3,771,811 and 4,202,559 disclose boards
in which one of the wheel-sets is fixed to the underside
of the board while the other is attached to the underside
of a rotatable platform at the other end of the board so
that the platform and its wheel-set are steerable as a
unit by a foot of the skater. The purpose of the steering
platforms on both boards is, according to the
specifications, to provide a board for children or novices
which may easily be foot steered without positional
shifting of the skaters body on the hoard.
OBJECT OF THE INDENTION
It is the object of this invention to provide a skateboard
which is steerable and is highly manoeuverable relatively
to conventional boards.
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SUf~f~RRY OF THE INVENTION
R skateboard according to the invention includes two
footboards with each footboard consisting of a foot
platform and a wheel-set which carries two wheels in axial
alignment fixed to the underside of the platform, a spacer
element for holding the footboards in a spaced
relationship and a pivot arrangement having a vertical
pivot axis connecting each footboard to the spacer element
to enable both footboards to pivot relatively to the
spacer element.
Further according to the invention each wheel-set includes
a resilient suspension member which is located in the
wheel-set to enable limited resilient pivotal movement of
the platform in a direction transverse to the direction of
the axis of rotation of the wheels of 'the wheel-set.
In one form of the invention each wheel-set includes a
wheel body, wheel axles which are fixed to and project
from opposite sides of the body with the wheels being
journalled for rotation on the axles, a first pivot pin
which is attached to the wheel body with its axis in a
vertical direction, a support member on the pivot pin, a
second pivot pin pivotally connecting the foot platform to
the support member with its pivot axis normal to the wheel
axis, resilient suspension means between the support
member and the underside of the foot platform for holding
the plaform horizontal and a pivot arrangement on the
spacer element which is pivotally engaged with the first
pivot pin between the wheel body and the support member.
Conveniently the wheel body and the support member of each
wheel-set are integral to provide a wheel-set body with
the support member pivot arrangements being engaged with
the first pivot pins of each wheel-set through slots in
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the wheel-set bodies. The slots in the wheel-set bodies
may have radially displaced vertical edges to stop
rotation of the spacer element pivot arrangements on the
first pivot pins to prevent the wheels from coming into
contact with the spacer element.
Still further according to the invention the pivot
arrangements on the spacer element each carry a rotatable
bearing which rides on horizontal faces of the wheel-set
body slots to prevent the pivot arrangements from binding
with the wheel-set bodies during pivotal rotation of the
footboards relatively to the support element.
The skateboard may include foot straps which are attached
to the foot platforms.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is now described by may of example only with
reference to the drawings in which:
FIGURE 1 is a partially sectioned plan view of one
embodiment of the skateboard of the invention,
FTGURE 2 is a side elevation of the Figure 1 board,
FIGURE 3 is an exploded perspective view as seen from
below of one of the footboards of the skateboard of
Figures 1 and 2,
FIGURE 4 is a sectioned side elevation of the assembled
footboard of Figure 3,
FIGURE 5 is a plan view of the Figure 4 footboard shown
sectioned on the line 5 - 5 in Figure 4, and
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FIGURE 6 is a side elevation of a second embodirnent of the
board of the invention.
DETAILED DESCRIPTION OF THE ILLUSTRATED Em80DImENTS
The skateboard of Figures 1 and 2 is shown in the drawings
to consist of two footboards 10 and 12 and a spacer
element 14 which is pivotally connected at each of its
ends to a footboard to hold the footboards in the spaced
relationship shown in the drawings.
Each of the footboards consists, as is more clearly seen
in Figures 3 and 4, of a wheel-set body 16 and a foot
platform 18.
The wheel-set bodies each include two stub axles 20 which
are threadedly located in bosses 22 which project from
opposite sides of the body, wheels 24 which are made from
a fairly hard resilient material and rotatably located on
the stub axles 20, an upper support arrangement indicated
generally at 26, a sector shaped slot 28 which is more
clearly seen in Figures 4 and 5, a first pivot pin 30, a
resilient suspension pad 32 and a second pivot pin 34 for
pivotally holding the fnot platform 18 to the support
arrangement 26.
The suspension pad 32 is made from a hard rubber or
suitable plastic and, as shown in Figure 3, includes a
rectangular base portion and two upwardly and outwardly
directed wings 35. The upper surface of the pad is grooved
between the wings to locate the pad on the pivot pin 34 in
use.
The support arrangement 26 includes two upwardly directed
gabled lugs 36 which are holed to receive the pivot pin 34
and a rectangular recess, not shown, in which the base of
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the suspension pad 32 is located in use.
The spacer element 14, consists of an elongated frame
member 37 which carries a pivot arm 38 on each of its
ends. The frame member is made from any suitably rigid
and robust material such as reinforced plastic, alluminium
or the like. The pivot arms 38 each consist of a pivot lug
40 which carries a suitable bush 42, a roller bearing 44
and a spigot 46 which is a press fit in a bore in the end
of the frame member 37. A locking pin 48 passes through
the spigot 46 and the frame member to hold the pivot arm
against rotation and withdrawal from the bore in which it
is located)
The slots 28 in the wheel-set body 16 are each outwardly
stepped at 50 to a dimension at which the roller bearing
44 on the pivot arm is a nice fit as shown in Figure 4.
To assemble the skateboard the pivot arm lugs 40 are
located in the slots 28 in the wheel-set bodies, the pivot
pins 30 are passed from the underside of the bodies
through the bush in the lugs 40 and are locked to the
bodies by lock nuts 52 which are located in recesses in
the bases of the suspension pad recesses in the support
arrangement 26.
The suspension pad 32 is now located in the recess in the
upper surface of the support arrangement 26 and the foot
platforms are pressed heavily down on to the wings 35 of
the suspension pad resiliently to deform the wings
downwardly against the bias of the pad material until
holes in lugs 54 on the undersides of the foot platforms
are in register with the holes in the support arrangement
gable lugs 36) The pivot pin 34 is now pressed through the
registering holes in the gable lugs 36 and lugs 54 on the
foot platform and locked in position by means of circlips
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as shown in Figure 4. The pivot pin is now firmly located
in the central groove on the upper surface of the
suspension pad firmly to locate the suspension pad in the
wheel-set. The upward bias of the suspension pad wings 35
on the underside of the foot platform holds the platform
horizontal while allowing a limited resilient pivotal
movement of the platform about the pivot axis of the pin
34.
From the above it will be appreciated that the foot
platforms 10 and 12 are rotatable about the axes A of the
pivot pins 30 within angular limits imposed on them by
vertical edges 51 of the slots 28 in the wheel-set bodies
16. This is illustrated in Figures 1 and 5 in which the
chain lines B illustrate the limit positions of the angle
of rotation of the support element relatively to the
footboards at which the vertical side edges of the slots
28 come into contact with the sides of the pivot arm lugs
40. At the Limit positions of rotation of the footboards
the wheels 24 are just out of breaking contact with the
spacer element 3? as illustrated on the left hand side of
Figure 1.
The skateboard of Figure 6, as with the skateboard of the
previous embodiment, includes two footboards 10' and 12'
and a spacer element 14. In this embodiment of the
invention, however, the foot platforms 18 are supported on
substantially conventional skateboard wheel-sets 52.
The spacer element 14 of this embodiment of the invention
consists of two metal straps 56 and a spacer 58 which is
sandwiched between and fixed to the straps to keep them
spaced apart vertically.
The wheel-sets 52 each consist of separate upper and lower
portions 60 and 62 and an annular rubber or like resilient
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torsion member 64. The lower portion 62 of each wheel set
includes a ring portion which tightly surrounds the
torsion member 64 with a ball and socket arrangement 66
connecting the outer ends of the wheel set components. A
pivot bolt 68 passes through the spacer straps 56 and the
bore of the torsion member 64 to be threadedly anchored in
the wheel set portion 60. The footboards, in this
embodiment of the invention, are therefore pivotable
relatively to the spacer element on the axes A.
The lower portion 62 of the wheel-sets enable the foot
platforms 18 resiliently to pivot in a direction
transverse to the spacer element 14 by the torsion members
64 being able resiliently to deform and so tilt within the
rings of the lower portion 62 of the wheel-sets while the
tilting motion of the platforms is supported by the ball
and socket joints 66 on the outer ends of the wheel-sets.
The footboards 18 of the skateboards of the invention may
conveniently include footstraps which are fixed to the
platforms to pass over the upper surfaces of the boards in
a direction transversed to the wheel axes. The upper
surfaces of each of the footboards preferably carries a
non-skid surface material 90.
The skateboard of the invention is primarily intended for
use as a dynamically operational vehicle for competitive
use. The board is steered or turned by the rider of the
board standing astride the board with his feet on the foot
platforms with his foot direction lying in the direction
of the wheel axes of the wheel-sets while the board is in
motion and splaying his feet to rotate the boards 10 and
12 about their pivot axes A so that each of the wheel sets
follows a common curved track with the centre of the curve
being the crossing point of lines in register with the
axes of the wheels on each footboard. The radius of the
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curve is determined by the degree of splay of the
footboards. The high performance skateboards of the
invention which include a resilient suspension member may,
however, also be turned by the rider halding his feet
parallel on the boards 10 and 12 and shifting his weight
above the board to tilt the board as is the case with a
conventional skateboard with non-steerable wheel-sets.
The optimum turning method of the board of the invention
is, however, a combination of both the turning of the
footboards about their vertical pivot axes A and by
simultaneous weight shift of the rider over the board to
tilt the footbaards against the bias of the pads 32. In
practice in very sharp turns at speed, with the board of
the invention the rider leans forwardly or backwardly by
as much as 45° towards the inside of the turn with the
boards tilted to their maximum extent to resist the
centrifical force generated in the turn. His feet and so
the footboards are either inwardly or outwardly splayed in
dependence on whether he is leaning forwardly or
backwardly so that the wheel axes point to the centre of
the turning radius. The manoeuvreability of the board is
obviously much greater than is the case with a
conventional skateboard with non-steerable wheel-sets with
which the wheel track of the board may only slightly be
varied or a board in which only one of the wheel-sets is
steerable. LJith boards with one steerable wheel-set, if
wheel skid is ignored, the turning radius will be the
meeting point of lines which lie on the axes of the two
wheel-sets. This meeting point will be brought
significantly closer to the board if the fixed wheel-set,
if it were capable of rotation, was now rotated in the
opposite direction to that of the first steerable
wheel-set to bring the meeting point on the wheel axle
lines far closer to the board significantly to decrease
the turning radius of the board as is the case with the
board of the invention.
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Nnother significant advantage which the board of the
invention has over conventional boards with non-steerable
wheel-sets or boards which have a single steerable
Wheel-set is that by pivotal movement of both the
footboards and suitable weight distribution the board can
be caused to follow a sharp sinusoidal track enabling the
board to be propelled at fairly high speed over a flat or
even an upwardly inclined surface.
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