Note: Descriptions are shown in the official language in which they were submitted.
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The invention relates to a winter sports device
with two tiltable skids mounted parallel about a longitu-
dinal axis in a frame. The skids are each connected by a
drive train to a foot plate for a user. The foot plate is
tiltably mounted in the frame in such a way, that the tilt-
ing movement of the footplate is transferred to the two
skids.
A winter sport device of this kind is known from
(German Patent Specification 2,707,364). The drive train
acting between the foot plate and the two skids is e.g. a
gear drive or a chain drive. The skids are formed like
ordinary skis. Steering is essentially effected by a
resolute and measured transverse force caused by body rota-
tion. In order to make this steering effect possible, the
forces for straight tracking should not be too strong; on
the other hand sufficient stability for straight running
is desirable.
As these two values counteract each other, a
certain practice period is necessary for the proper hand-
ling of the winter sport device even for the skilled sports-
man. It is desirable to shorten this practice period
considerably, so that the device can be handled from the
very beginning with sufficient safety also by less skilled
users without considerable practice and without special
energy. A winter sport device should not only be useable
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in alpine terrain with mechanical lifts, but especially
in terrain with slopes of lesser gradient, because such
terrain is within easier reach for many users than alpine
skiing terrain.
It is also desirable to improve the winter sport
device for running in deep snow and generally for running
in soft snow. In these conditions the skier has to exert
considerable energy because of the increased surface resis-
tance so that deep snow running remained reserved to a
relatively small group of skilled skiers. At the same
time the winter sport device must remain useable on hard
runs, because on many occasions the user has at least
partially also to use or traverse hard runs, e.g. when
running downhill to the ski lift. For safety reasons alone
therefore, the winter sport device must be safely steerable
on hard, icy runs.
The invention seeks to provide a winter sport
device of the above type in which, without diminishing
the track holding ability during straight running, a stronger
influence of the tilting movement of the skids on the turning
forces is achieved, so that safe turns are achieved without
the transverse forces caused by body rotation. This does
not diminish the possibilities of running with body
rotation. Simultaneously the usefulness of the device
on hard runs remains or is even improved and the usefulness
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in deep or soft snow is considerably improved.
The invention is characterized in that
(a) the skids each comprise upwardly curved
ends and an interposed centre region
curved in the opposite direction;
(b) each skid comprises a straight track-
ing edge;
(c) each outer edge of the skids comprises
a concavely curved tracking edge.
The turn achieved by the inclination of the two
skids. In soft or deep snow respectively the turns are
essentially effected by the curved, shovel-like ends of the
skids, the curved area of which effect a turn by inclination,
similar to a water ski.
On hard, icy runs essentially the tracking forces
of the edges are effective. When the two skids are inclined,
the straight tracking edge of one skid remains engaged
with the ground. However, the outer edge of the other
skid increasingly engages the ground, i.e. with increasing
transverse inclination of the skid the forward and rearward
regions of the concavely curved tracking edge increasingly
engage the ground. Thus, the straight tracking force of
one of the skids is superimposed by an increasing arc
tracking force of the other skid, resulting in a turn, the
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arc of which depends on the inclination of the skids. In
other words, the engaging regions between the curved outer
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edge of the skid and the ground are shifted with increas-
ing transverse inclination of the skid further to the
front and the rear, and thus to those parts, where the
tracking edge and the longitudinal direction of the skid
form an increasingly steeper angle.
Preferably, the straight tracking edge is formed
on the inner edge of the skid in the centre region of the
skid. Furthermore, it is especially advantageous to make
the curved tracking edges, towards both ends of the skids,
longer than the straight tracking edge. Although the
engaging pressure of one of the inner edges of the skids
is increased by inclination of the skids, the straight
tracking force caused thereby is superimposed by a consider-
ably greater torque, which is exerted by the front and
rear sections of the curved outer edge of the skid engaging
the ground with a longer lever arm relative to the centre
of gravity of the device. This increasing superimposition
of the turning forces is continuous, so that a continuous
changeover from straight running to turning is possible.
Because the centre region of the skids is curved
in the opposite direction to the general longitudinal curva-
ture, the highest loaded and ground engaging regions during
straight running are not located in the longitudinal centre
of the skids, but in two regions spaced therefrom and shifted
to the front and rear, so that stable running properties are
achieved without a tendenc~ to rotate.
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The curving of the centre region of the skids
oppositely upwards ensures that with an inclined position
of the skids the centre section of the concavely curved
outer edge of the skids is not loaded on hard ground, so
that two outer engaging points are created, which has a
positive effect on the turning stability in wavy terrain.
Also on terrain with moguls and bumps the outer edge of the
skids does not momentarily engage the ground with the centre
section, i.e. with the section essentially in the longitu-
dinal direction of the skids. Such an engagement wouldinterrupt the turn by momentary straight running, thus
leading to unstable turning.
A possible negative effect of this opposite
curving of the centre region of the skids in deep snow
is compensated for very easily by over-dimensioning the
shovel-like ends of the skids.
In order to achieve an out of proportion increase
of the tracking force in a turn with extremely inclined
skids, the curvature of the curved tracking edge may
increase towards both ends, e.g. like an elliptic section,
the main axis of the ellipse being parallel to the longi-
tudinal axis of the skids.
In order to increase the directional stability,
preferably a rear straight tracking edge along the longi-
tudinal direction of the skids is arranged in the rear
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`I l 63661
section of the skids, which e.g. is formed by a longitudinal
groove in the bottom surface of the skids or by a longi-
tudinal keel. This rear straight tracking edge enables a
stable return into the straight position after each turn
or after side slipping, i.e. during slipping over the
edges like in skiing.
An oversteering is prevented and, after the end
of a turn, when setting the edges, a return to the fall line
is effected. The angle of the foot plate does not have to
be overly inclined with respect to the body axis of the user,
which would be necessary when turning back over the downhill
edge. This would not be possible anatomically on steeper
slopes as; the user could slide from the foot plate when
attempting it. With the device according to the invention
this back-turning effect still lies in the range of the up-
hill edge loading, i.e. in a medium angle between the slope
and the horizontal. In this way a traversing turn is
possible, so that the speed can always be safely controlled
in steeper terrain, and one is not forced into an overly
steep downhill direction in order to perform parallel turns.
Only the device according to the invention makes
a way of running possible in which the turn is essentially
effected by the foot joint, so that unskilled users can
run downhill after a short period in a way resembling
~25 skiing or skate boarding. More skilled users add the
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sliding principle, so that the downhill running adventure
is further increased.
The invention is further described below in
connection with the accompanying drawings which, however,
do not limit the scope of the invention. In the drawings:
Figure 1 is a simplified perspective view of
a winter sport device with two skids during a turn on
hard ground,
Figure 2 is a side elevation of the device accor-
ding to Figure 1,
Figure 3 is a simplified plan view of the skids
of the device according to Figures 1 and 2,
Figure 4 is a front elevation of the device,
Figure 5 is a bottom view of one of the skids,
Figure 6 is a cross section of a skid, and
Figures 7 through 9 are simplified cross sections
of modified embodiments of the skids.
The winter sport device shown in Figures 1, 2,
and 4 comprises a foot plate 1, on which the user stands
freely, i.e. without bindings. The foot plate 1 is tiltably
mounted in a frame 2. Two parallel skids 3 are also tiltably
mounted in the frame 2. The skids 3 and the foot plate 1
are connected by a drive train (not shown), e.g. by a gear
drive or a chain drive. In this way a tilting movement of
the foot plate 1 in the frame 2 is translated into a
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corresponding tilting movement of each of the skids 3 as
indicated in Figure l.
The skids 3 each have upwardly curved, shovel-like
ends 3a and 3b with an interposed centre region 3c, which is
oppositely curved relative to the curve direction of the ends
3a and 3b of the skids, so that an overall curvature results
as distinctly shown in Figure 2.
The plan vie~ (Figure 3) shows, that each inner
edge 4 of the skids comprises a straight tracking edge 4a.
The outer edge 5 of the skids is concavely curved. Figure 3
indicates that the curved outer edge 5 of the skids is formed
by a section of an ellipse ~, the main axis of the ellipse
being parallel to the longitudinal axis of the skids. This
results in a curvature of the outer edge 5 of the skids,
which increases towards both ends of the skids.
Figure 3 also shows that the straight tracking
edge 4a is shorter than the curved outer edge 5 of the skids,
which overlaps towards both ends of the skids. The tracking
forces of the straight tracking edge 4a indicated in Figure
3 by arrows 4b therefore have a shorter lever arm relative
to a centre or centre of gravity of the winter sport device
than the tracking forces indicated by arrows 5a in Figure
3, which have a greater distance from this centre when the
skids are tilted, which results in a turn.
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Figure 1 indicates by shading the distance
betw~een the outer edge 5 of a skid and a plane, icy ground
area. It can be seen that - as indicated by arrows 5b -
the regions of the outer edge 5 of the skid engaging with
the surface have shifted in the direction towards the two
ends 3a and 3b of the skids. A still further shift towards
the ends of the skids results from a greater inclination
of the skids 3.
Figure 5 shows in a bottom view of a skid 3, that
apart from a central longitudinal groove 7 positioned
over the whole length of the skid, a longitudinal groove 8
is provided adjacent the inner edge 4 of the skid, the edges
or the rear section respectively of the inner edge 4 of the
skid separated by the longitudinal groove 8 forming a rear
straight tracking edge. Instead of the longitudinal groove
8 or in addition to it, the straight tracking edge can also
be formed by a longitudinal keel 9 (Figure 7) protruding
from the bottom surface of the skid.
In order to engage the straight tracking edges
4a with the ground during straight runs, i.e. with a level
position of the foot platel and the skids 3, the bottom
surface of the skids is slopingly inclined in transverse
direction towards each inner edge 4 as shown in the
embodiments according to Figures 4, 6, 8, and 9. Figure
9 shows that this transverse inclination of the bottom sur-
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face of the skids can be greater in one of the skids thanin the other. This asymmetric arrangement of the skids 3
takes into account the normally asymmetric position of the
user relative to the longitudinal direction of the skids.
Normally right-handed persons stand on the foot plate in
such a manner, that the left foot is positioned in the front,
and the right foot in the rear of the foot plate. This
results in an anatomically caused variation of the turning
procedure. In a right hand turn the pressure on the rear
foot can be varied continuously by angling the leg in order
to achieve a good turn control. In a left hand turn the
rear leg has to be stretched when tilting the foot plate 1,
which can lead to oversteering with unskilled users,
especially on soft ground. If the inner edge 4 or the
straight tracking edge 4a respectively of the right skid
(as viewed in the direction of travel) is formed stronger,
e.g. by a greater transverse inclination of the bottom
surface of the skid, as indicated in Figure 9, the described,
anatomically caused variation between right handed and
left handed turns is eliminated. This effect can be
compensated for by curving the outex edge 5 of the left
skid more sharply than the outer edge 5 of the right skid.
In the modified embodiment according to Figure 8
the transverse inclination of the bottom surface of the skids
3 increases from the front (indicated in full lines) towards
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the rear (indicated in broken lines). This results in a
stronger tracking effect on the inner edge 4 of the skids
in the rear region, whereby a stabilizing effect is achieved
similar to that by the rear longitudinal groove 8 (Figure
5) or the rear longitudinal keel 9 (Figure 7).
There is a correlation between the curvature in
the vertical longitudinal plane of the ends 3a, 3b of the
skids and the curvature in the horizontal plane of the outer
edges 5 of the skids, in that the increase of the curvature
of the outer edges 5 of the skids towards their ends is made
sharper with a sharper curvature of the ends 3a, 3b of the
skids in the vertical plane.
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