Note: Descriptions are shown in the official language in which they were submitted.
YR, YMH-7806
1 - 201 ~85X
ENDLESS TRACK BELT FOR SNOW MOBILE
BACKGROUND OF THE INVENTION
l. Eield of the Invention
The present invention relates to an endless
track belt for snow mobiles. More particularly, the
present invention relates to an endless track belt
provided with a plurality of tractive projections
effectively reinforced by a plurality of transversal
rigid members, and having an enhanced durability for
practical use.
2. Description of the Related Arts
It is known that a conventional snow mobile is
provided with an endless track belt traveling along an
endless track defined by at least one driving wheel and
at least one guide roller.
The endless track belt comprises an endless
substrate belt to be traveled along the endless track, a
plurality of tractive projections protruding from the
outside periphery of the substrate belt at predetermined
intervals, and transversal rigid members embedded in the
track belt.
When a portion of the endless track belt is
located in a lower half portion of the endless track,
the tractive projections on this portion of the track
belt come into contact with a snow stratum and move the
snow mobile forward or backward. The tractive
projections and the endless substrate belt are
reinforced by the transversal rigid members.
In the conventional endless track belt, each
transversed rigid member is usually arranged in a center
portion of a region lying over both the corresponding
tractive projection and a portion of the substrate belt,
from which portion the tractive projection protrudes
outward. In this type of conventional endless track
belt, when the tractive projections come into contact
with a snow stratum, the transversal rigid member does
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not satisfactorily absorb a stress created in the
tractive projection, and thus does not sufficiently
prevent deformation of the tractive projection. The
deformation of the tractive projection results in
difficulty in obtaining an effective and sufficient
insertion of the tractive projection into the snow
stratum, to a satisfactory depth. Therefore, it is
difficult for the conventional endless track belt to
produce a sufficient traction force for the snow mobile.
Also, the deformation of the tractive projection causes
an increased friction between the endless track belt and
a suspension rail, and thus the suspension rail is
locally loaded, and accordingly, locally abraded.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an
endless track belt for a snow mobile, in which belt a
plurality of tractive projections to be inserted into
snow stratum are effectively reinforced by a plurality
of transversal rigid members.
Another object of the present invention is to
provide an endless track belt for a snow mobile, which
belt is capable of creating an enhanced force of
traction for the snow mobile.
Still another object of the present invention is to
provide an endless track belt for snow mobile, and
having a reduced frictional resistance of portions of
the snow mobile with which the track belt comes into
contact while the track belt is traveled, and thus an
enhanced durability.
The above-mentioned objects can be attained by the
endless track belt of the present invention for a snow
mobile, which comprises the following members:
(l) an endless substrate belt to be traveled along
a closed track, a lower half portion of which an endless
track belt comes into contact with a snow stratum to
thereby move a snow mobile forward;
(2) a plurality of tractive projections protruding
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from an outside periphery of the substrate belt at
predetermined intervals, extended at right angles to the
traveling direction of the substrate belt, and each
havinq a pointed end portion thereof; and
(3) transversal rigid members for reinforcing the
substrate belt and the tractive projections, in the same
number as that of the tractive projection, embedded
within the substrate belt, and extending along the
tractive projections, said individual tractive
projection and the corresponding transversal rigid
member satisfying a relationship such that, when a
portion of the substrate belt located in the lower half
portion of the closed track is in parallel to the
horizontal line, the pointed end portion of the
individual tractive projection arranged on the
above-mentioned portion of the substrate belt positions
within a shadow region of the corresponding transversal
rigid member cast in the direction in parallel to the
perpendicular line, and when a portion of the substrate
belt located in the lower half portion of the closed
track is inclined at an angle 0 to the horizontal line,
the pointed end portion of the individual tractive
projection arranged on the above-mentioned position of
the substrate belt is positioned within a shadow region
of the corresponding transverse rigid member cast in the
direction of an angle of l/2 0 to the perpendicular
line.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure l shows a front view of a snow mobile having
a pair of endless track belts;
Fig. 2 shows an explanator~ view of a portion of an
assembly of an endless track belt;
Fig. 3 shows a locus of a tractive projection of an
endless track belt of the present invention, where the
tractive projection has sunk into a snow stratum;
Fig. 4 shows a geometric locus of a pointed end of
the tractive projection shown in Fig. 3;
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Fig. 5 is a cross-sectional profile of a portion of
a conventional endless track belt, inclined from the
horizontal plane;
Fig. 6 is a cross-sectional profile of a portion of
a conventional endless track belt located in a portion
of a closed track thereof in parallel to the horizontal
plane;
Fig. 7 shows a cross-sectional profile of a portion
of an endless track belt of the present invention,
inclined from the horizontal plane; and
Fig. 8 shows a cross-sectional profile of a portion
of an endless track belt of the present invention,
located in a portion of a closed track thereof in
parallel to the horizontal plane.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The endless belt of the present invention for a
snow mobile comprises the elements of (l) an endless
substrate belt, (2) a plurality of tractive projections
protruding from the outside periphery of the substrate
belt at predetermined intervals, and ~3) a plurality of
transverse rigid members for reinforcing the substrate
belt and the tractive projections, in the same number as
that of the tractive projections.
Referring to Figs. l and 2, a snow mobile l is
provided with a pair of skis 2 arranged in the front
lower portion of the snow mobile l, and a pair of
endless track belts 3 each traveling along a closed
circling track defined by a drive wheel 4, an idle
roller 5, a suspension rail 6, and optionally, one or
more guide rollers 7.
~ hen the snow mobile l is placed on a horizontal
plane, the bottom face of the ski 2 and the bottom face
of the suspension rail 6 are substantially in parallel
to the horizontal plane. The endless tractive belt 3 is
provided with an endless substrate belt 8, a plurality
of tractive projections 9, and a plurality of
transversed rigid member l0. The tractive projactions 9
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are formed on the outside periphery of the endless
substrate belt 8 at predetermined intervals, extend at
right angle to the traveling direction, or the
longitudinal axis, of the substrate belt, and has
pointed end portions thereof.
The endless track belt 3 is further provided with a
plurality of driving projections 11 protruding from the
inside periphery of the substrate belt 8. The driving
projections 11 are geared to mesh with a plurality of
pins 10 formed on the side surfaces of the drive wheel 4
to travel the endless track belt 3. Also, the endless
track belt 3 is traveled along the closed circling
track, on a lower half portion of which the endless
track belt 3 comes into contAct with the snow stratum
and moves the snow mobile 1 forward. The lower half
portion of the closed track has a substantially
horizontal portion defined by the suspension rail 6 and
a ~ownwardly inclined portion defined by the drive
wheel 4 and the suspension rail 6. In this horizontal
portion of the lower half portion of the closed track,
the endless track belt 1 slides on the suspension
rail 6.
Referring to Fig. 2, the endless substrate belt 8
in the endless track belt 3 is composed of a core
layer 8a, an upper reinforcing fabric layer 8b,
laminated on the upper surface of the core layer 8a, a
lower reinforcing fabric layer 8c laminated on the lower
surface of the core layer 8a, an upper covering rubber
layer 8d laminated on the upper reinforcing fabric
layer 8b and a lower covering rubber layer 8e laminated
on the lower reinforcing fabric layer 8c. The tractive
projections 9 are formed on the upper covering rubber
layer 8d of the substrate belt 8 at predetermined
intervals and extend at right angles to the traveling
direction of the substrate belt 8. The driving
projections 11 are formed on the lower covering rubber
layer 8e of the substrate belt 8 at predetermined
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intervals.
In Fig. 2, the endless track belt 3 is provided
with a plurality of transversed rigid members 12 in the
same member as that of the tractive projections 9. The
transversal rigid members 12 are arranged, for example,
between the core layer 8a and the upper reinforcing
fabric layer 8b of the substrate belt 8, protruded into
the corresponding tractive projections 9 so that they
are embedded within the portions of the track belt 1
lying over both the substrate belt 8 and the
corresponding tractive projections 9, and extend in
parallel to the tractive projections.
In Fig. 2, three endless track belts 3 are
connected to each other through connecting members 13.
The core layer 8a of the endless substrate belt 8
comprises a flexible material, for example, reinforced
by aramide, polyester or nylon fibers or a rubber
material steel cords. ~he tractive projections 9
comprise an elastic material, for example, a soft rubber
material which is resistant to frictional contact with
snow and serves as a cushion material when the endless
track belt 1 comes into hard contact with a solid body
while the snow mobile is running.
Each individual tractive projection 9 has a
substantially triangular cross-sectional profile and is
provided with a pointed end portion 9a.
Where a portion of the substrate belt located in
tne lower half portion of the closed track is inclined
at an angle g to a horizontal line, and a tractive
projection formed on the above-mentioned portion of the
substrate belt comes into contact with an upper surface
of a horizontal snow stratum, the pointed end of the
tractive projection sinks into the horizontal snow
stratum in the locus as indicated in Fig. 3.
Referring to Fig. 3, where a portion 8f of the
substrate belt comes into contact at an angle 0 with an
upper surface 15 of a horizontal snow stratum, while the
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portion 8f of the substrate ~elt moves in the direction
shown b~ the arrow A, the pointed end 9b of a tractive
projection 9 sinks into the snow stratum along a
locus 14. The locus 14 is inclined at an angle 1~2 ~ to
a pexpendicular line X-X.
Referring to Fig. 4, the portion 8f of the
substrate belt is represented by a line A-O which is
inclined at an angle o to a horizontal line Z-O. When a
pointed end 9b of the tractive projection 9 moves from a
position A to a position O in the closed track, and no
slippage occurs between the tractive projection and the
snow stratum, the snow mobile is moved horizontally
forward for a distance L represented by a line OZ in
Fig. 2.
The triangle AOZ is an isosceles, and thus the
angle AZO is equal to (90 - o/2) degrees. Accordingly,
the angle ZAQ of the locus AZ to the perpendicular
line Q-Q drawn through a point A is l/2 0 [180 - 90
_ (90 - 1/2 0)]-
Therefore, when a pointed end of a tractive
projection moves in a snow stratum in the direction of
from A to Z, inclined at an angle 1/2 ~ to the
perpendicular line Q-Q, the tractive projection is
stressed by a force in the opposite direction of from Z
to A.
Figure 5 shows a cross-sectional profile of a
portion 3a of a conventional endless track belt. In
this portion 3a, a portion of a substrate belt 8 is
inclined at an angle ~ to a horizontal plane, and a
tractive projection 9 comes into contact with a
horizontal upper surface 15 of a snow stratum.
Accordingly, a stress P is applied to the tractive
projection 9 in the direction inclined at an angle 1/2
to the perpendicular line Q-Q. This stress must be
borne by a transversal rigid member 12, to reinforce the
tractive projection 9 and the substrate belt 8.
The transversal rigid member 12 can bear the
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stress P in a shadow region S thereof casted in the
opposite direction to that of the stress P. This
opposite direction is inclined at an angle l/2 ~ to the
perpendicular line.
Referring to Fig. 5, a pointed end portion 9a of
the tractive projection 9 is not contained in the shadow
region S of the transversal rigid member 12, and
therefore, the pointed end portion 9a is not
satisfactorily reinforced by the transversal rigid
member 12.
Referring to Fig. 6, when a portion of a
conventional endless track belt 3 comes into contact
with a horizontal upper surface 15 of a snow stratum and
is moved horizontally in the direction, as shown by an
arrow, along a suspension rail 6, a horizontal stress F
and a perpendicular stress P are applied to a tractive
projection 9 in the directions as shown in Fig. 6,
respectively.
Accordingly, a sliding metal member 16 fixed to the
endless track belt 3 comes into contact with and slides
on a sliding face 6a of a suspension rail 6. If the
perpendicular stress P applied to the sliding metal
member 16 is unevenly distributed on the sliding face
thereof, the sliding resistance produced between the
sliding face 6a of the suspension rail 6 and the sliding
metal member 16 becomes uneven.
This uneven perpendicular stress P results in a
decreased durability of the sliding metal member 16 and
the suspension rail 6.
In Fig. 6, the pointed end portion 9a is outside of
the shadow region X of the transversal rigid member 12
cast in the perpendicular direction, and thus the
transversal rigid member 12 cannot satisfactorily bear
the perpendicular stress P applied to the pointed end
portion 9a of the tractive projection 9. Therefore, the
perpendicular stress P is unevenly applied to the
sliding metal member 16.
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_ 9
Referring to Fig. 7, when a portion of an endless
track belt 3 of the present invention comes into con~act
with a horizontal snow stratum in a manner such that a
portion of a substrate belt 8 is inclined at an angle 0
to the horizontal face 15 of the snow stratum, and a
pointed end portion 9a of a tractive projection 9 comes
into contact with the snow stratum and moves in the
direction as shown by an arrow in Fig. 7, a stress P is
applied to the pointed end portion 9a in the direction
inclined at an angle 1/2 0 to the perpendicular
line Q-Q.
As Fig. 7 clearly shows, the pointed end portion 9a
of the tractive projection 9 is located within the
shadow region S of the transversal rigid member 12 cast
in the direction inclined at an angle 1/2 ~ to the
perpendicular line Q-Q. Therefore, the stress P can be
sufficiently borne by the transversal rigid member 12.
Therefore, in the endless track belt of the present
invention, the pointed end portion 9a is reinforced by
the transversal rigid member 12, and thus the
deformation of the tractive projection 9 when the
tractive projection 9 penetrates the snow stratum is
minimized, and thus the endless track belt can provide a
maximum traction force.
Also, referring to Fig. 8, a portion of an endless
track belt 3 of the present invention comes into contact
with a horizontal snow stratum and moves in the
direction as shown by an arrow.
The pointed end portion 9a of the tractive
projection 9 is located within a shadow region K of the
transversal rigid member 12, and thus the perpendicular
stress P created in the direction as shown in Fig. 8 on
the pointed end portion 9a of the tractive projection 9
is sufficiently borne by the transversal rigid
member 12, and is evenly applied to the sliding metal
member 16. Therefore, the sliding resistance between
the sliding metal member 16 and the sliding face 6a of
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the suspension rail 6 is lowered. This lower sliding
resistance results in an increased durability of the
sliding metal member 16 and the suspension rail 6.
In the endless track belt of the present invention
the cross-sectional profile of ths individual tractive
projection along the longitudinal axis o~ the track belt
is preferably asymmetrical with respect to a line Y-Y
drawn throuqh a pointed end 9b of the tractive
projection 9 and a transversal axis 12a of the
transversal rigid member 12, as shown in Fig. 7.
This asymmetric cross-sectional profile of the
individual tractive projection is effective for reducing
the resistance thereof to penetration of the snow
stratum and for producing a floatation force when the
tractive projection comes into contact with the
horizontal snow stratum.
Also, in the endless track belt of the present
invention, the individual tractive projection is
preferably provided with at least one linear protrusion
formed on the outside periphery of the tractive
projection and extending in parallel to the tractive
projection, as shown in Fig. 2.
The linear protrusion i5 effective for increasing
the friction between the outside face of the individual
tractive projection and the snow stratum, and thus for
enhancing the tractive effect of the tractive
projection.
The endless track belt of the present invention has
the following advantages:
(1) The transversal rigid member can sufficiently
bear the stress created on the pointed end portion of
the corresponding individual tractive projection due to
the resistance of the snow stratum against the movement
of the corresponding individual tractive projection.
Therefore, the transversal rigid member arranged in
accordance with the present invention effectively
reinforces the corresponding tractive projection and the
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corresponding portion of the substrate belt. Namely,
when the tractive projection is stressed by the snow
stratum, the deformation of the tractive projection is
prevented by the corresponding transversal rigid member.
Therefore, the endless track belt of the present
invention can produce a high tractive force for the snow
mobile.
(2) The perpendicular stress applied to the
sliding faces of the sliding metal member of the endless
track belt and the suspension rail is even, and thus the
sliding resistance between the sliding faces of the
sliding metal member and the suspension rail is even and
small. This even and small sliding resistance results
in enhanced durability of the sliding metal member and
the suspension rail.
(3) The transferred rigid member is effective for
decreasing a moment created on the individual tractive
projection, and thus the undesirable deformation of the
corresponding position of the substrate belt is
prevented.
Therefore, the flexural fatigue of the
substrate belt is decreased or prevented.
(4) The production of the endless track belt of
the present invention can be easily carried out without
changing the design and the elements of the belt.
