Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02349735 2001-06-06
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MOTORCYCLE TRACTION ACCESSORY DEVICE
Field of the Invention
The invention relates to motorcycles and more particularly to a traction
device for winter driving of motorcycles.
Background of the Invention
U.S. Patent 5,474,146 granted December 12, 1995 to Yoshioka et al relates
to a snow vehicle and more particularly to a vehicle of the saddle-riding type
having
a rear traction device of the endless belt variety.
U.S. Patent 4,534,437 granted August 13, 1985 to Howerton relates to a
snow track belt for a motorcycle wherein the track belt device is associated
with
a rear wheel of the motorcycle without significant modification to the
motorcycle.
Canadian Patent 458,162 to Cote relates to a bicycle modified for winter
driving including a traction device to which the bike chain is connected.
Canadian Patent Application File Nos. 2,1 14,150 and 2,154,729 are also
directed to modifying bicycles for winter driving, both traction devices being
associated with the rim of the rear wheel, the tire being removed.
None of the prior art noted above provides a simple, but expedient means
for providing a traction device which is mounted in association with the rear
wheel
of a motorcycle wherein the rear tire remains on its rim and the traction belt
is
associated with it in a simple but effective manner, to enable ease of
conversion
to winter driving.
Summary of the Invention
Accordingly, there is a need for a simple traction device for conversion to
winter driving which can be assembled with a motorcycle without removing the
rear tire from its rim and yet provide good traction and allows flexibility to
the
driver to lean into corners when steering.
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The invention in one broad aspect provides a traction device for detachable
association with a motor bike for winter driving, the bike having a rear wheel
assembly including an axle and a rubber tire supported by laterally spaced
bike
struts. The traction device comprises laterally spaced opposed side strut
assemblies each having a forward end and rearward end, a traction wheel
assembly
and an endless track. The side strut assemblies each include means adapted to
pivotally connect the forward end of each of the strut assemblies to the bike
adjacent the rear axle of the bike wheel assembly with the strut assemblies
extending rearwardly of the bike. The traction wheel assembly is rotatably
supported by the. rear ends of the strut assemblies. The endless track has
means
for cooperating with the rubber tire of the bike and the traction wheel
assembly to
maintain the endless track centered on the rubber tire and the traction wheel
assembly.
The motorcycle can be further modified by attaching a ski to the front wheel,
allowing for even more off-road riding in looser snow conditions.
Brief Description of the Drawings
Fig. 1 is a side view of a motor-cross type of motorcycle showing the
inventive traction device or accessory for winter riding attached thereto.
Fig. 2 is a rear perspective view of the traction device but omitting the
front
portion of the cycle for the purposes of clarity.
Fig. 3 is a sectional view along line 3-3 of Figure 2.
Fig. 4 is a sectional view along line 4-4 of Figure 2.
Fig. 5 is a side view of the rear traction wheel and support strut.
FIG. 6 is a perspective view of the connection of the weight to the strut.
Fig. 7 is an exploded view of the rear axle of the cycle according to the
prior
art.
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Fig. 8 is an exploded view of the rear axle of the bike with the additional
traction support arm bracket in accordance with the invention.
Fig. 9 is a side view of a modified embodiment of the invention.
Fig. 10 is a further side view showing the embodiment of Fig. 8.
Fig. 11 is a perspective view of part of the rear axle assembly and struts.
Fig. 12 is an enlarged perspective view of the traction assembly strut and
the spring biased feature.
Fig. 13 is a top view of a modification of the configuration of the traction
assembly strut.
Description of the Preferred Embodiment
Turning to Figures 1 and 2, a motocross type of motorcycle 20 of standard
construction has rear wheel assembly 22 including axle 24, rim 26 and tire 28
and
support struts 30, 32, front wheel 36, handlebars 38 and seat 40. The traction
device 50 includes rearwardly extending struts 52, 54, extending rearwardly
from
the rear axle assembly 22 of the bike 20. Traction device 50 also includes
rear
traction wheel assembly 56, weights 58, and track 60.
Turning to Figure 3, a sectional view of track or belt 60, belt 60 is
constructed of rubber like material, similar to that used in snowmobile tracks
and
has upper or outer surface 70, lower or inner surface 72 and laterally opposed
side
edges 74, 76. Imbedded in track 60 and spaced at longitudinal intervals along
the
belt are laterally extending reinforcing plastic bars or rods 78 which provide
rigidity
to the track 60 and prevent the track from flexing too much into a curved form
about tire 28. Laterally spaced protrusions or nubs 80 extend downwardly from
inner surface 72 of belt 60 and prevent the track from running off tire 28 and
provide a centering means for maintaining track 60 in appropriate alignment
with
the tire 28 and with the rear traction wheel assembly 56. Spikes 82 in track
60
extend outwardly to enhance traction on ice or hard snow. Any number of spikes
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may be used and they are fastened to track 60. Track 60 also has laterally
extending longitudinally spaced convex shaped ribs 86 extending outwardly of
the
outer surface 70.
Turning to Figure 4, being a partial sectional view of the rear traction wheel
assembly 56, the assembly includes a shaft 90 supported for rotation on
bearings
92, 94 which are carried by the rear end 96, 98 of struts 52, 54. Wheel discs
100, 102, 104, 106 are secured to shaft 90 at laterally spaced intervals so
that
nubs or protrusions 80 run within the spaces between the outer adjacent discs
100, 102 and 104, 106. It will be appreciated that outer ends of shaft 90
could
be secured to blocks supported by the struts 52, 54 and the wheel discs
individually journalled on the shaft. In this alternative embodiment, spacers
between the wheel discs to keep them in appropriate laterally spaced
relationship
are preferred.
Figure 5 is a schematic view of the rear wheel assembly from the side
showing the rear end 98 of strut 54 bifurcated with a square bearing block 1
10
mounting bearing 94 is slidable within the bifurcation. Tension on the belt 60
can
be adjusted by a block and screw mechanism 1 12 cooperating with the ends of
the
bifurcation and the bearing block 110 in known manner.
Returning to Figures 1 , 2 and 6, disc weights 114, 1 1 6 are held by rod 1 18
which is mounted between blocks 120, 122, which blocks are secured to struts
52, 54 intermediate the ends thereof so that the weights do not interfere with
travel of the track 60. The weights may be selected as circumstances dictate,
but
are sufficient to maintain and bias the track 60 in contact with the ground,
yet will
permit pivotal or rotational movement of the struts 52, 54 about the axle 24
of the
motorcycle. Weights are secured to rod 1 1 8 and rod 1 18 to blocks 120, 122
by
collar 126/Allen screw 128 mechanisms, one of which are shown in Figure 6
wherein the rod 1 18 and weights 114, 116 can be axially removed from the
block.
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Any means of detachably mounting the weights to the struts 52, 54 is
appropriate,
provided the weights do not slip from side to side on rod 118.
Figure 7 provides a sectional view through a typical rear axle assembly 24
of a motorcycle (prior art). Assembly 24 has hub 130 from which spokes 132
extend outwardly to support the rim 24 (Figures 1 and 2). Secured to hub 130
is
rear chain sprocket 134 and disc brake plate 136. Hub 130 is tubular with a
central bore 138 and is supported by bearings 140, 142 which are housed in
recesses 144, 146 of hubs 130. The rear ends 148, 150 of struts 30, 32 support
the hub 130 on shoulders 152, 154 and bolt 156 with head 158 and nut 160
extends through ends 148, 150 and hub bore 130 to secure ends 148, 150 in
proper spaced relationship to support the hub for rotation. Various washers
have
been omitted for clarity.
Turning to Figure 8, a view similar to that of Figure 7, Figure 8 illustrates
the
rear axle assembly 24' modified to enable securement of the rear ends 96, 98
of
traction assembly struts 52, 54. However, depending on the bike to which the
device is to be used, axle assembly 24' may be modified by lengthening bolt
156
or preferably, as herein shown, using two threaded bolts 164, 166 and
internally
threading bore 138' at 168, 170 respectively. Traction device strut ends 96,
98
are located outwardly of rear axle supporting strut ends 148', 150'. Suitably
washers and bearings associated with strut ends 96 and 98 and its connection
to
the rear axle assembly through bolts 164, 166 have not been shown.
Turning to Figures 9 and 10, a second embodiment of the traction device is
shown with respect to maintaining a downward bias to the traction device. In
place of the weights 114, 1 16 to keep the track assembly biased and in
contact
with the ground, there are provided spring loaded struts 52a and 54a. As shown
in Figures 9 - 12, block 182, only one side is shown, the other side being a
mirror
image thereof is splined to or otherwise secured to shank 186 of bolt 1 66a
for non-
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rotation therewith. Pivotally located between block 182 and end 150 of strut
34a
and pivotal on shanks 164, 166 are struts 52a, 54a. The strut 54a has an
internal
bore 200, angled as shown in Figures 10, 11 and 12. Within bore 200 is rod 202
having an end 204 extending within offset recess 206 of block 182 and the
opposite end 210 within bore 200 in contact with spring 214, placing spring
214
within bore 200 under compression. The angle of bores 200, and the offset of
recess 206 from the axis of hub 130a and the placement of spring 214 under
compression, bias or tending to force rotation of and strut 54a in the
direction of
the ground which will maintain the traction assembly in contact with the
ground.
However, there is still limited rotational or pivotal movement of the traction
assembly provided about bolt 166a with this modified embodiment. Limit blocks
220, 222 which prevent over-rotation of strut 54a either upwardly or
downwardly,
engage blocks 182 to limit rotation. It will be appreciated that limit blocks
could
be placed on the inside of strut 54a to cooperate with upper and lower
portions of
the bifurcated end 1 50a of strut 34a. Further, the spring loaded mechanism of
strut 54a including rod 202 and spring 214 could be modified so that it is
associated with end 1 50a of strut 34a, a block like 182 being secured to end
strut
1 50a.
With the embodiment having spring loaded or biased struts 52a, 54a, the
weights 114, 116 are no longer required. Preferably with this modified spring
biased embodiment a traction idler assembly 230 as shown in Figures 9 and 10,
is provided. Each assembly 230 has two right angled support arms 232, 234
pivoted at 236 to the struts 52a, 54a at the right angle of the arms, with
idler
rollers 240, 242 rotatably supported at the ends of the support arms 232, 234,
respectively. The idler assembly 230 assists in maintaining track 60a in
contact
with the ground.
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Figure 13 shows a top view of the traction assembly 50a illustrating a
preferred form of the struts 52a, 54a wherein they are configured so the rear
portions thereof 250, 252 are substantially within the lateral area of the
track 60a
whereby the struts 52a, 54a will interfere less with movement of the assembly
50a
downwardly in soft snow for contact with more solid ground for traction.
Various modifications to the invention over that illustrated herein will be
appreciated by those skilled in the art and which fall within the scope of the
invention.
