Adjustable apparatus and kit for a coupled snowmobile suspension (CA)

CA 02358154 2001-10-03
the angle of incidence, the slide rails will act as a ramp forcing the rear of
the snowmobile upward.
That is, with the slide rails angled in an upward incline due to the
independent deflection of the
front suspension arm, but not the rear suspension arm, the snowmobile will hop
over the bump,
imparting a secondary jolt which increases in intensity with the speed of the
snowmobile. This
secondary jolt also results in a loss of control and a reduction of the speed
of the snowmobile.
On the other hand, a coupled suspension system is one in which, for example,
the rear
portion of the suspension system reacts (i.e., is coupled) to the compression
experienced by the front
portion of the suspension system as the snowmobile passes over a bump in the
terrain. In effect, the
bump is « communicated » to the rear portion of the suspension, causing the rear
portion to be pulled
upward toward the chassis before the rear portion actually reaches the bump.
This reduces the angle
of incidence between the slide rail and the bump, which thereby reduces the
secondary jolt
experienced by the rider. As a result, a coupled suspension system provides
for an improved ride
because the coupled suspension is better suited to adjust to varying terrain
conditions.
Manufacturers have developed a variety of ways to provide coupled suspension
systems,
which typically involve restricting the amount of longitudinal movement of the
rear suspension arm.
Such systems are shown in U.S. Patents Nos. 5,881,834, 5,692,579, 5,667,031,
and 5,944,134.
The suspension system disclosed in Polaris’ 5,692,579 (« ‘579 ») patent is shown
in Figs. 1-4,
where Fig. 1 shows the overall suspension system removed from the snowmobile,
and Figs. 2-4
show the design approach used to couple the suspension system. As disclosed in
the ‘579 patent and
depicted in Figs. 2 and 4, the linkage of the rear suspension arm 20 with the
lower pivot arm 26
permits the front of the slide rails 10 to rise substantially independently of
the rear portion of slide
rails. During this independent movement of the front portion of the
suspension, the lower pivot arm
26 pivots from the rearward position shown in solid lines in FIG. 2 to the
forward position depicted

CA 02358154 2001-10-03
in broken lines. At the point which the front surface 27 of the lower pivot
arm 26 engages the front
adjuster block 30, further independent upward movement of the front end of the
suspension is
prevented. That is; further upward movement of the front of the slide rails 10
is mechanically linked
through the adjuster block 30 to the rear suspension arm 20, causing upward
movement of the rear
of the suspension (the rate of upward movement of the rear of the suspension
may or may not be
equal to the rate of movement of the front of the suspension, depending on the
specific geometric
configuration of the system).
The degree of independent movement afforded to the front of the suspension
rails 10 is
dependent on the distance between the rear stop 32 and the front adjuster
block 30 in comparison to
the width of the lower pivot arm 26. The rear surface 31 of the front adjuster
block 30 thus provides
a limit on the relative forward movement of the lower end of the suspension
arm 20 with respect to
the slide rail 10.
The Polaris~ system of the ‘579 patent further provides variability to the
position of this
limit, thereby giving the rider some control over the performance
characteristics of the suspension.
This variability is provided by using rectangular adjuster block 30, which has
four surfaces that are
each positioned at varying distances from the block’s central mounting point,
as indicated by
distances « dl » through « d4 » in Fig. 4. By rotating the block to select one of
the surfaces, the
position of the limit with respect to the lower end of the suspension arm 20
can be controlled.
However, with the above Polaris~ system, it is difficult for the rider to make
a desired
adjustment to the adjuster block 30, especially when the rider is in the
field. To make an
adjustment, the rider must first loosen the central mounting point (a bolt).
Then, the rider must
manage to rotate adjuster block 30, either with his fingers or with the aid of
another tool, to the

CA 02358154 2001-10-03
desired location, and then retighten the central mounting point. The rider
must then repeat these
steps for the adjuster block on the opposite side of the slide rail.
Considering that the rider may
wish to make such adjustments while in the field, where he/she would encounter
other obstacles,
such as deep snow, cold weather, and generally unfavorable conditions for
handling tools and
equipment, it is apparent that making such adjustments to the adjustable block
30 in order to
compensate for differing terrain conditions is difficult with the above
Polaris~ system.
It is therefore the object of this invention to provide an apparatus, in the
form of an after-
market upgrade kit, for installation onto a coupled snowmobile suspension
system of the kind
described in Patent No. 5,692,579 that, when installed, allows for a quick and
easy adjustment of the
front to rear coupling.
It is further an object of the present invention to provide an apparatus, in
the form of an
after-market upgrade kit, specifically configured to be installed onto the
Polaris~ line of
snowmobiles.
Summary of the Invention
It is the object of the present invention, therefore, to provide an apparatus
and an after-
market upgrade kit constructed and arranged to be installed onto a coupled
snowmobile suspension.
The upgrade kit includes a shaft having an axis of rotation, a pair of
coupling blocks, and an indexer
plate. The coupling blocks are adapted to be fixedly connected relative to the
axis of rotation at
each end of the shaft so that a torque in the shaft will be transmitted to the
coupling blocks. The
coupling blocks have a plurality of sides corresponding to a plurality of
positions of the coupling

CA 02358154 2001-10-03
blocks, each of the sides being located at a different distance from the axis
of the shaft when the
coupling blocks are connected to the shaft. The indexer plate is adapted to
engage one of the
coupling blocks at a selected positions of the coupling blocks. The shaft is
constructed and
arranged to be mounted between a longitudinal pair of slide rails of the
snowmobile suspension, and
the coupling blocks are adapted to be rotated about the axis to thereby adjust
the coupling of the
snowmobile.
Other obj ects and advantages of the present invention will be realized in
accordance with the
following detailed description, appended drawings, and claims.
Brief Description of the Drawings
The various embodiments of the present invention are shown throughout the
drawings, in
which:
Fig. 1 is a perspective view of a coupled snowmobile suspension of the prior
art;
Fig. 2 is a plan view of Fig. 1, and also shows the coupling apparatus;
Fig. 3 is an enlarged view of the coupling apparatus of Fig. 2;
Fig. 4 is an enlarged view of the coupling block of Figs. 2 and 3 of the prior
art;
Fig. 5 is a perspective view of the preferred embodiment of the apparatus of
the present
invention showing the assembly thereof before attachment to the snowmobile
suspension;
Fig. 6 is a plan view of the shaft of the upgrade kit of the preferred
embodiment;
Fig. 6B is a section view of the rectangular portions of the main shaft of
Fig. 6;
Fig. 6C is a plan view of a second embodiment of the main shaft, where the
coupling blocks
are integrally formed with the main shaft;
Fig. 7 is a plan view of a coupler block of the upgrade kit of the preferred
embodiment;

CA 02358154 2001-10-03
Fig. 8 is a side view of a coupler block of the upgrade kit of the preferred
embodiment;
Fig. 9 is the plan view of Fig. 7 showing dimensional attributes;
Fig. 10 is a perspective view of a coupling block having mounted thereto a
ball spring
plunger, which is the preferred embodiment of a protrusion of the upgrade kit;
Fig. 11 is a side view of Fig. 10;
Fig. 12 is a side view of a coupling block having mounted thereto a second
embodiment of a
protrusion mounted to a coupling block;
Fig. 13 is a side view of a coupling block having mounted thereto a third
embodiment of a
protrusion mounted to a coupling block;
Fig. 13B is a perspective view of a second embodiment of the indexer plate and
coupling
blocks, where the indexer plate has mounted thereto the protrusions of Figs.
11, 12, 13, and the
coupling block includes a plurality of depressions;
Fig. 14 is a plan view of the indexer plate of the upgrade kit of the
preferred embodiment;
Fig. 15 is a plan view of a support plate of the upgrade kit of the preferred
embodiment;
Fig. 16 is a plan view of a Polaris~ XTR.A-10 snowmobile suspension system
without the
upgrade kit installed;
Fig. 17 is an enlarged view of the coupling portion of Fig. 16;
Fig. 18 is a plan view of a portion of the suspension system of Fig. 16 with
the upgrade kit
installed;
Fig. 19 is a top view of the upgrade kit installed onto the Polaris~ XTRA -10
snowmobile
suspension system of Fig. 16; and
Fig. 20 is a depiction of the position of the lower arm engaged with a coupler
block in two
different positions of the coupler block.
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CA 02358154 2001-10-03
Fig. 21 is a snowmobile comprising the upgrade kit of the present invention.
Detailed Description
Referring now more particularly to the Figures, wherein like reference numbers
are used for
like components where applicable, the apparatus of the present invention,
which is also referred to
as an upgrade kit, is generally indicated at 40 and is illustrated in Fig. 5.
Generally, the upgrade kit
40 is constructed and arranged to be installed onto an adjustably coupled,
snowmobile suspension
system, so that when installed, the adjustment of the coupling is made quicker
and easier. More
specifically, the upgrade kit 40 is configured to be assembled onto the
Polaris~ line of snowmobiles
that are originally manufactured with an adjustable, coupled suspension
systems, as described above
with reference to Figs. 1-4.
Refernng to the Fig. 5, the upgrade kit 40 comprises, among other components,
a shaft 42,
two adjustable coupling blocks 46, 48, an indexer plate 50, two bolts 54, 58,
and two plate brackets
62 & 66. Figure 5 shows the upgrade kit 40 as an assembly, but not installed
onto the suspension
system, and Figs. 6-1 S show each component separately. The adjustable
coupling blocks 46, 48 are
hereinafter referred to as the coupling blocks 46, 48, and shaft 42 is also
referred to as the main
shaft 42.
As seen in Figs. 5 and 6, the main shaft 42 comprises a cylindrical portion 68
and two
rectangular portions 70, 72 mounted at each end of the main shaft 42. The axis
of the main shaft 42
is designated as reference numeral 74. The corners of the rectangular portions
70, 72 preferably
include longitudinal chamfers 76 that extend a length L3 from the end of the
main shaft 42, which
are configured to accommodate the coupling blocks 46, 48, described below.
Each end of the main
7

CA 02358154 2001-10-03
shaft 42 has a threaded bore 78 formed to a depth of length L3 therein. The
threaded bores 78
accommodate bolts 54 and 58 in order to mount the upgrade kit 40 to the
snowmobile suspension.
The rectangular portions 70, 72 and cylindrical portion 68 of the main shaft
are preferably
integrally formed with the cylindrical portion 68 of the main shaft 42, and is
preferably machined
from a single piece of machine stock. Of course, the main shaft 42 may be
formed from other
manufacturing techniques, such as by a casting, or the rectangular portions
70, 72 can be separately
formed and welded or otherwise connected to the cylindrical portion 68 to form
main shaft 42.
Also, the entire main shaft 42 may be rectangular, and the cylindrical portion
68 need not be
present. In the preferred embodiment, the main shaft 42 is made of aluminum.
However, it is
contemplated that any other suitable material can be used, as long as the
material selected is
sufficiently strong and rigid.
Each coupling block 46, 48, shown separately in Fig. 7, is a generally
rectangularly-shaped,
rigid structure and includes a generally rectangular bore 80. The dimensions
of the rectangular bore
80 are substantially the same as the dimensions of the rectangular portions
70, 72 of the main shaft
42, such that the rectangular portions 70, 72 therein can be matingly
inserted. The rectangular
portions 70, 72, therefore, transmit torque from the main shaft 42 to the two
adjuster coupling
blocks 46, 48 during rotation of the main shaft. The axis 74 of main shaft 42,
when inserted into
coupling blocks 46, 48, is coincident with the centers of the rectangular
bores 80. The corners of
the rectangular bore 80 are, preferably, fillet radiused in a size to prevent
interference with the
chamfers 76 of the rectangular portions 70, 72. Also, the outside corners of
each coupling block 46,
48 are preferably rounded with radii Rl, R2, R3, and R4 to facilitate rotation
of the blocks.
Although in the preferred embodiment the adjuster coupling blocks 46, 48 are
separate
structures from the main shaft 42, it is also contemplated that the adjuster
coupling blocks 46, 48
8

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wherein the shaft is mounted between said slide rails,
wherein the coupling blocks are adapted to be rotated about said axis to
thereby
adjust the coupling of the snowmobile.

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