Note: Descriptions are shown in the official language in which they were submitted.
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MET~OD OF r~-~IN~ A 8~F-pRopEL~ED P~Y8ICA~ 8~ATEBOARD/RIDER
, AND sRAT~RQp~n FOR REALIZING THg h~-.
Fiel~ of tpe ~nventton
-The present invention relates to the field of sports/games/
re ~ tion, and particularly relates to skateboards which provide
special, integrated measures for physically driving the skateboard.
Backgroun~ of the Invention
In a primary configuration, a skateboard comprises an
elongated, suitably designed footboard from which two pairs of
rollers are suspended. Optionally, a skateboard can further
comprise supplementary equipment, e.g. a brake, a flywheel, a lamp,
a marker, a buffer, etc. Normally, in the course o~ skateboarding,
turning is made possible when the footboard of skateho~rd is
parallel to the skateboard~ g path while riding straight by
slanting the footboard to either side with respect to its
iongit~ nal axis. This action can be realized by means of a
3 specific suspension of the rollers. For performing a curve, the
inclination of the footboard results in a front and a rear roller,
the "inner" rollers with respect to the curve, being mutually drawn
together, whereas the other two rollers, the "outer" ones with
respect to the curve, are mutually drawn apart.
It is obvious that proper propelling of the skat~bo~rd is
performed by the rider pushing off from the ground (and/or by
riding downhill) so that a skateho~rd/rider-system as a physical
phenomenon, i.e. skateboard and rider functionally united into a
combined, independent unit, can be discussed merely within the
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2063916
period of the c~n~l~ption of mass force~ previously accumulated ~or
- in the case of riding downhill, by using gravity force).
Attempts to assign to a skateboard/rider-system the character
of a physica} phenomenon without using gravity force or a special
source of energy, respectively, i.e. solely on the basis of the
physical engagement of the rider, are known.
From U.S. patent specification 4,915,403 to Wild et al. a
l'skateboard with a mechanical drive" is known, having a footboard
which is, in the area of the middle of the longitudinal extension
o~ the footboard, transversely divided into a front, fixed section,
and a rear, pedal section. The footboard sections are
interconnected by a skateboard frame. The pedal section is, by
means of linkages comprising push rod, a crankshaft and a toothed
segment, as well as by means of a gear train bound to the toothed
segment and comprising four pairs of toothed wheels and a
termination toothed wheel, which is bound to a roller shaft of the
rear skateho~rd rollers, motion-transferably interconnected with
respective skatPho~rd rollers, each of which is connected to the
shaft by means of an overrunning clutch.
According to the above reference, the skateh~rd provided
essentially has the same height as skatebo~rds without propelling
gearings, and diverse operational possibilities are retained, such
as ease in negotiating curves and maneuverability.
However, the height of the skat~ho~rd of Wild can only be
diSCllcs^~ in connection with the front, i.e. fixed, footboard
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section of the skateboard, not in connection with the rear, i.e.
pedal section, except at a position when its pedal function is
arrested which, however, is not in conformity with the primary aim
or object of the solution. Analogously, regarding the "diverse
possibilities" the following points are noted. Curves can easily
be negotiated and the skateboard easily handied under the condition
only that the pedal function is arrested, i.e. both footboard
sections straightened to be coplanar. In the state when the
skateboard is physically pushed, only the rider's foot resting on
the front footboard section of the skateboard is left to accomplish
normal riding ("normal" meaning the possibilities offered by the
skateboards without propelling gears). Thus, the maneuverability
is obviously and considerably affected. So, for example, the
possibility of making jumps, when the pedal section i5 lifted, is
totally excluded.
Further, the length of the footboard of the skateho~d is
limited to a length of at least two feet and there is a dànger of
toppling on one side or the other with ~e ~e_~ to the direction of
riding as well as backwards ovcr the rear rollers (as a consequence
that propelling tends to jerk the skat~o~rd from under the rider's
feet).
From the functional point of view the known solution shows a
further disadvantage which cannot be neglected, namely the driving
torsional moment is enforced intermittently: a driving phase is
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followed by an idle one, the latter is followed by a driving
phase, etc.
Summary of the Invention
The present invention overcomes the disadvantages set
forth above, and provides a skateboard which can physically be
driven by means of movements proper to a rider used to riding
skateboards without driving gears.
For negotiating curves, the footboard of a skateboard is
tiltable within limits, whose extreme values are defined by
constructional measures, and that reasonably rapid swinging of
the footboard, limited to a correspondingly small angle, with
respect to a given plane which is horizontal for straight
riding and is in negotiating a curve, tilted to the direction
of the geometrical center of the curve, in practice generates
no perceivable meandering of the skateboard. The invention is
based on converting swinging of the footboard to propelling of
the rollers of a skateboard.
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According to the invention, there is provided in a
skateboard having an elongated footboard straddling a central
longitudinal vertical plane for the skateboard, forward and
rearward longitudinally spaced suspensions secured to a bottom
surface of the footboard, a pair of laterally spaced rollers
carried by each suspension, each of said suspensions including
a roller shaft for mounting said pair of rollers, said forward
and rearward suspensions being arranged in a V-relationship to
define a central longitudinal swing axis extending through
said forward and rearward suspensions, each of said
suspensions having a resilient mounting for each roller shaft
so as to permit pivotal movement of the roller shaft and thus
steering of the skateboard in response to a swinging movement
of the footboard by a user about said longitudinal swing axis,
and drive means located on opposite sides of the central
longitudinal vertic~l plane of at least one of said forward
and rearward suspensions, each of said drive means including a
resiliently biased, vertically mounted, reciprocative,
elongated drive member having an upper end in sliding
engagement with the bottom surface of the footboard, said
drive member being operatively connected to said roller shaft
for driving the roller shaft in response to swinging movement
of the footboard about the longitudinal swing axis.
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The preferred exemplary embodiment of the invention will
hereinafter be described in conjunction with the figures,
wherein like designations denote like elements.
Brief Description of the Drawings
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Fig. 1 is a schematic view of a skatPho~rd of the invention,
with the footboard of the skateboard cut away to expose the
substructure of the skateboard.
Fig. 2 is a side elevational view of a skateboard of Fig. 1,
with the front wheel assembly shown in cross section.
Fig. 3 is a front elevational view of a skateboard of Fig. 2
from the left (i.e. the front view), with the section relating to
the front right roller represented as a vertical sectional
elevation which corresponds to line III-III of Fig. 2, and shows
a corresponding toothed rack not covered by the sectional plane
(one of axles and accompanying two gears omitted to improve the
clarity of the drawing).
Fig. 4 is a cross-sectional elevation view taken on line IV-IV
of Fig. 3.
Fig. S i~ a schematic view of a pair of gearings (without
rèspective toothed racks) of an axle (front or rear? of the
skatPho~rd.
~ Fig. 6 is a schematic vièw of a gearing on the right side with
respect to the riding direction, partly taken apart.
Fig. 7 is a schematic front or rear view of the skateboard,
having an extremely tilted footboard, the geometry of swinging
being shown.
Fig. 8 is a view analogous to Fig. 7 showing the opposite
tilting of the footboard.
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2063gl6
~eta~l-d Description of the Preferred ~mbodiments
The ska~eho~rd comprises a footboard 1 which is composed and
designed in accordance with the respective objects and having on
a lower side a front substructure assembly 2 and a rear
substructure assembly 3 suspended at the front and the rear end
sections, respectively. The connection of the footboard 1 and the
substructure assemblies 2, 3 is a direct one, similar to that of
skateboards without incorporated driving gearings.
The substructure assembly 2, 3 has a two-column suspension 4
(front); suspension 5 (r~ar) which, as such, belongs to the prior
art. The two suspensions 4, 5 are structurally egual to each
other, and arranged in kn~wn manner mirror-symmetrically with
respect to a vertical central plane positioned transversely to the
direction of the movement of the skatebo~rd. When observing the
representation of Fig. 1, the structural feature ~ust mentioned
appears such that of the two-column suspension 4 of the front
substructure assembly 2, a rigid, internally rotatable and break-
able column 6, and of the two-column suspension 5 of the rear
substructure assembly 3, respectively, an elastically flexible
column 7, is visible.
The columns 6, 7 of either suspension 4, 5 are arranged in a
V-relation in the central longitudinal vertical plane of the
skateboard, which feature, in combination with other features of
the suspensions 4, 5, makes it possible that on tilting of the
footboard 1 to the left or to the right, respectively, with regard
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to the direction of riding the skateho~rd, the front substructure
assembly 2 and the rear substructure assembly 3 are definitely
swung in opposite directionS - each assembly around its own
vertical axis, which coincides with the axis of the rigid column
6. These shiftings in functional meaning result in turning of the
skateboard.
Except in view of the mentioned feature that the suspensions
4, 5 are arranged as mirror images, the front substructure assembly
2 and the rear substructure assembly 3 are structurally equal to
each other. In order to simplify the description of the
skateboard, only the front substructure assembly 2 and the front
suspension 4 will hereinafter be referred to, but will include the
rear substructure assembly 3 and the rear suspension 5.
According to the invention there is to each side (- end) of-
a shaft housing 8, the latter arranged crosswisely to the columns
6, 7 at the root section of the V-arrangement of said coIumns of
the suspension 4, attached a gearing 9, 10, said gearings being
preferably designed so as to create mutual miL.o, ~ymmetry with
respect to the intermediate vertical Iongit~l~inAl plane of the
skàtehoArd .
A roller shaft 11, bearing at its free end sections skatehoArd
rollers 12, is inserted through the shaft housing 8 and the
.gearings 9,10.
For the solution of the problem of the invention it is really
indispensable to provide a pair of gearings 9, 10 for each shaft
2~0'~'9'1 6
11. In principle, the installation of gearings at both shafts,
i.e. at the front and at the rear roller shaft, is optional but the
tests performed, as well as diverse practical aspécts tWhich will
be discussed in more detail later), lead to the conclusion that it
is convenient to use two pairs of gearings as shown in Fig. 1.
Possible initial doubts as to the effect that the gearings in the
arrangement mentioned might result in an aimless constructional
jamming of the skateboard, disappear on becoming aware that
according to the invention the suspensions which, as generally
known, are "critical" (and therefore expensive) components of
skateboards, need not be divided to front/rear and left/right ones,
respectively, as is the case in the prior art analyzed.
The gearing 9 according to the invention is composed of a
box~ r~ mounting casing 13 which is attached to the free end of
the shaft housing 8 and in which, beside the roller shaft 11, a
shaft 14 for carrying gears, conveniently di~oscd above the roller
shaft 11, and an intermediate shaft 15 also for carrying gears,
dis~Gscd by height between the shafts 11 and 14, but shifted
rearwards with respect to the direction of riding the skatehoArd,
are mounted. On the side oriented to the roller 12 of the
skateho~rd, the mounting casing 13 is closed by a vertical wall 16
(please also compare Fig. 6). Finally, attached to the latter is
a mounting cover 17, which provides another series of bearings for
pivoting the shafts 11, 14, 15. In the ceiling part of the wall
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of the mounting cover l? there is, directly at the wall 16, a
recesS 18 for conveying a toothed rack 19 as explained below.
The shaft 14 supports a pinion 20 which is directly bound to
the shaft and cooperates with the toothed rack 19, as well as a
further gear 21, which is by means of an overrunning clutch 22
(e.g. a grip roller and expanding friction clutch) connected to the
shaft 14. The pinion 20 resides inside the mounting cover 17 and
projects into an appropriate circular recess 26 of the wall 16,
whereas the gear 21 accompanied by its overrunning clutch 22
resides inside the mounting casing 13 and is arranged at an axial
distance from the journal of the shaft 14.
The intermediate shaft 15 supports a gear 23 designed to mate
with the gear 21. Gear 21 has a diameter greater than that of gear
23, and on the side oriented to the vertical wall part of the
mounting casing 13 supports a further, larger gear 24. The two
gears 23, 24 are directly connected to the intermediate shaft 15.
The roller shaft 11 supports a gear 25, driven and designed
to mate with the gear 24, whose diameter i5 larger than that of
gear 25. Gear 25 and shaft 11 are directly connected.
Reces~ec to convey shafts 11, 15 analogous to recess 26, are
provided in the wall 16. Wall 16 also provides an upright
trough-shaped guide 27 (Fig. 6) for accommodation and guiding of
upright toothed rack l9, the inner cross-section of the guide 27
~oinciding with the recess 18.
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On shaft 14, in the axial interspace between the gear 2~ and
its over~lnn~n~ clutch 22, respectivelY, and the bearing of the
shaft 14, a suitably pre-stressed helical torsion-spring 28 is
located, whose one end is formed like a hinge and is, by means of
tangential approaching to the surface mantle of the shaft 14,
connected to the latter, and whose other end is designed like a
hook and i5 thereby connected to the mounting casing 13. The
windings of the spring 28 are tightened when the toothed rack 19
is moved down, i.e. they accumulate potential energy necessary for
returning (lifting) the toothed rack 19 to its original position.
It is clearly evident from Fig. 5 that, in the case of existence
of two gearings 9, 10 bound to a respective roller shaft 11, one
of the two springs 28 is coiled right-handedly and the other one
is coiled left-~n~e~ly. An embodiment of a left-hand coiled
helical torsion spring 28 is pictorially represented in Fig. 6.
The gearing is designed on the principle that one stroke of
the toothed rack 19 results in one revolution of the shaft 14.
P Naturally, at a complete revolution of the shaft 14 the windings
of the spring 28 do not thoroughly clamp the mantle surface of the
shaft, and the ability of springness-accumulation of the spring is
thereby not thoroughly exhausted.
The inte~G~.-.e~ion of the shaft 11 and the roller 12 is taken
from the prior art and designed by providing a roller bearing 29
~Fig. 3) and an overrunning clutch 30.
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In a pre~erred embodiment of the invention there i8 with
respect to the overrunning clutch 30 belonging to the roller 12,
as well as with respect to the overrunning clutch 22 which belongs
to the gear 21, among known overrunning clutches chosen the one
designed on two mutually movable rings inserted one into another
and each carrying an appropriate series of roller needles, whereby
the inclination sections are in the outer ring. The
two overrunning clutches 22 of rollers 12 boun~ to a common
.
shat 11 thus work in the same direction of rotation.
Figs. 1 through 6 represent a skateboard which is neutral with
respect to the footboard l and is balanced with respect to the
spring 28. The four toothed racks l9 are forced upwards to the
footboard 1 under the influence of the ~e~uk..ing forces of the
springs 28.
CorL~ary to the above mentioned state, Fig. 7 schematically
~e~Lesents a skateboard having a footboard l tilted to one of two
`limiting positions by force, Fig. 8 representing a state
co~ on~ng to tilting the footboard into the opposite limiting
position. The two springs 28 referring to the toothed racks 19,
which are pushed down by the footboard 1, are then tightened
(stressed), the other ones are then slack (loose). When riding,
the positions shown in Figs. 7-8 represent negotiation of uu~ves
by the skatehoArd in one or the other direction.
206391B
Fig. 7 comprises three plane coordinate system~ co~e~onding
to the swinging axis o of the footboard 1. The x-y system denptes
the position of the footboard l when riding straight, t~é x'-y'
system denotes the position thereof at extreme turning to one
direction (an analogous position as to extreme turning to the other
direction being represented in Fig. 8), and the x"-y" system
denotes an optional intermediate position of turning the
skateboard, i.e. sliqht turning. Arched arrows A added to the
ordinate planes y, y', y" in Fig. 7 indicate the possibility of
performing the swinging of the footboard with respect to the
respective ordinate planes in the course of riding on a skateboard,
with the amplitude of swinging each reasonably measured off. In
principle or advantageously, respectively, there is foreseen that
in the case of all arrows A, essentially the same angle of swinging
is in question although the choice of the extent o~ swinging as
such is within the individual discretion or the user's mastering
of the rolling technique, and the extent both depends on the
embodiment and riding features, respectively, and is structurally
limited to one or the other side merely by the extreme possible
tilting position here indicated by the x'-y' system.
The swinging of the footboard 1, as explained above, is in
accordance with the fundamental conception of the invention, as
defined in the introduction, exploited in the range of angles
indicated by the arcuate arrows A for generating the propelling of
the skat~ho~rd. Experiments have shown that swinging generated by
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a re~sonAhly high frequenCY and reasonably small amplitude with
respect to an optionally chosen plane y, y", naturally without
e~cee~i~g the limit plane y', does not result in risky, uneven
riding of the skateho~rd (in fact, swinging essentially means
creating miniature curves, i.e. meandering). However, it can be
exploited as an appropriate basis for generating an appropriate
propelling moment of rotation. The circumstance that the gearing
g is unavoidably embodied as a "light" one, is an obvious
accompanying feature of the concept as set forth above. Having
provided both roller shafts 11 with gearings 9, which means that
the driving load is every time divided between two gearings 9, the
skateboard as a whole meets the requirements regarding solidity,
typical for articles of this type.
A ska~eho~rd according to the invention provides possibilities
for starting riding either by pllC~;ng off the yLOul~d tsimilarly to
skateho~rds without a driving mer~n;sm) or by tre~ng on the
footboard and starting swinging of the footboard of the skateho~rd.
When pllch;ng the toothed rack 19 of the gearing 9 downwards,
the shaft 14 obtains levorotation; the overrunning clutch 22 is
thrown in gear and hence the gear 21 rotates as well. The rotation
of the shaft 14 is followed by tightening of the spring 28. From
the gear 21 the rotational moment is conveyed to the gear 23, by
means of the latter it is conveyed to the gear 15 and hence to the
gear 24, which gears are thus turned dex~lo~o~atorily. From the
gear 24 the rotational moment is conveyed to the gear 25 now
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driven, an~ by means of the latter conveyed to the roller shaft 11.
Evidently, the gear 25 and the shaft 11 obtain levorotation; the
overrunning clutch 30 of the roller 12 is put into gear. It is a
result of the transmission disclosed that a stroke of the toothed
rack 19 is converted into propelling rotation of the roller 12.
At realization of the above disclosed working stroke of the
toothed rack 19 of the gearing 9, the tbothed rack of the gearing
10 belonging to the same roller shaft 11 follows the lifting of the
footboard of the skateboard under the influence of the force of
unwinding the respective spring. Hereby, the connection of the
shaft 14 and the gear 21 of the gearing 10 is broken by means of
the overrunning clutch.
At turning, particularly at sharp turning, the difference
between the number of revolutions of the outer rollers and the
inner rollers 12 cannot be neglected, in principle. The
possibility is not excluded that in the case of realizing the above
disclosed swinging, also in the course of turning of the
skateho~rd, the drive actively influences merely the inner roller
12, which rotates slower, i.e. the number of revolutions of the
outer roller might exceed the one really attained by the gearing.
In this casQ the overrunning clutch 30 of the outer roller enables
free rotation of the latter.
Naturally, the overrunning clutches 30 are also necessary for
riding a skateboard backwards, in that case without putting the
driving gearings into gear.
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From the above discusSion~ it follows that with respect to
the lower ~ide of the footboard 1 the tip portion of each toothed
rack 19 performs a motion (Fig- 8) composed of a straight, radial
component R created by tilting the footboard 1 i.e. by swinging the
footboard 1 around the longitudinal axis 0, and also composed of
a circular component C created by swinging the substructure
assembly 2, 3 to perform turning, i.e. by swinging around the
vertical main axis of the suspension 4, 5. In order to avoid the
risk of possible non-reversibility of the footboard 1 and the
toothed rack 19, there is at the top of each toothed rack 19
foreseen a ball bearing 31, known per se, not represented in the
drawing.
A
