Rear suspension system for a land vehicle (CA)

2191 ~u8
the downward movement of the front portion of the lateral
slides by means of coil springs and a shock absorber unit.
Furthermore, the shock absorber unit exerts a downward force
on both the front and rear portions of the slides.
Another example of a rear suspension system for a
snowmobile vehicle is U.S. Patent No. 4,407,386 to Yasui et al.
This patent discloses a suspension unit comprising a first
shock absorber in a front portion of the rear suspension
system, and a second shock absorber in a rear portion of the
rear suspension system. The first shock absorber is connected
to a proximal end of a guiderail by means of a cross tube,
which is pivotally supported to the vehicle by means of bolts.
The second shock absorber is connected to a distal end of the
guiderail by means of bellcranks and arms. The bellcranks are
pivotally supported on an axle which is journaled in the body
of the snowmobile vehicle. Furthermore, the rear portion of
the rear suspension system comprises a strap for limiting the
maximum vertical travel of the guiderails with respect to the
body of the vehicle at such time as the vehicle is vertically
lifted off the ground. Accordingly, this patent limits the
vertical lift of the guiderails by means of a two sets of shock
absorber units, inc combination with springs, a strap,
bellcranks and arms.
Other examples of patented rear suspension systems
for land vehicles and snowmobiles include: U.S. Patent No.

2191008
5,033,572 to Zulawski, U.S. Patent No. 4,787,470 to Badsey,
U.S. Patent No. 4,546,842 to Yasui, U.S. Patent No. 3,913,692
to Lohr et al, Japanese document 62-214065, and Japanese
document 3-157283.
While each of the above described and cited rear
suspension systems for land vehicles function adequately, they
each have certain drawbacks. The major drawback is that the
rear suspension systems are mounted to the underside of the
chassis at both a front and rear portions thereof. The dual
attachment of the prior art suspension systems in some
circumstances add increased weight to the vehicle, reduce
travel of the suspension, and increase the drag on a returning
section of an endless track thereby decreasing the maximum
speed achievable.
Therefore, what is desirable in a rear suspension
system for a land vehicle is a generally centrally mounted
rear suspension system capable of providing improved
acceleration and cornering, an increase in the maximum speed
achievable, a reduction in the weight of the vehicle by
reducing the number of components in the suspension system, and
an improved shock system for decreasing the workload of the
components of the suspension system.

2~ 91008
OBJECTB AND SOMMARY OF THE INVENTION
It is therefore the general object of the present
invention to provide a single generally centrally mounted
structure in a rear suspension unit of a land vehicle, such as
snowmobiles and other recreational vehicles.
Another object of the invention is to provide a rear
suspension system for a land vehicle which can provide for an
adjustment between alternative riding conditions during weight
transfer of the vehicle, especially during acceleration and
cornering.
Additionally, it is a further object of the invention
is to reduce the weight of the rear suspension system by
reducing the number of components therein.
Furthermore, it is a further object of the invention
is to transfer the energy impact on the land vehicle toward the
center of gravity of the land vehicle, thereby reducing the
kick back effect, and transferring the energy impact away from
the driver of the vehicle.
In accordance with the invention, these and other
objectives are achieved by providing a suspension system for
the rear portion of a land vehicle comprising a single mounting
structure in a central portion of the suspension system, and

CA 02191008 2001-04-20
further providing a caeight dynamic compensator for a_Llowing
adjustment between alternative riding condition.
Thus, as embodied and broadly described herein, the
invention seeks to provide a suspension assembly for a
snowmobile vehicle comprising:
– two substantially parallel and spaced apart elongated
slide members defining a longitudinal axis, connected
together with transversally mounted bridge members, each said
slide member having a first curved ending portion and a
second ending portion f~~r connection of ending wheels;
– two substantially parallel elongated pivoting arms,
each having a first end pivotally connected to a respective
one of said glide members at a first connection point spaced
apart from said first ending portion and a second end adapted
for connection to a vehi~~le chassis;
– a first transversal. rod, adapted for connection to the
vehicle chassis, resi=l_i_ently connected to said slide members
and pivotally connected t.c~ said pivoting arms through another
transversal r_od disposed between the pivoting arms between
said second end and said first end; said another transversal
rod being pivotally connected to the curved portion of the
slide members. through a horizontal rod disposed between said
curved portions of said slide members.
_ , _

CA 02191008 2001-04-20
As embodied and brc:~adly described herein, the invention
also seeks to provide a suspension assembly for a snowmobile
vehicle comprising:
– two substantial=Ly parallel. and spaced apart elongated
~ slide members defir7.inc~ a longitudinal axis, connected
together with transversally mounted bridge members, each said
slide member having a f=first curved ending portion and a
second ending portion for. connection of ending wheels;
– two ,substanti<~lly parallel elongated pivoting arms,
each having a first end. pivotally connected to a respective
one of said slide membe._s at a first connection point spaced
apart from said first ending portion and a second end
adapted for connection tc~ a vehicle chassis;
– a fir:~t transversal rod, adapted for connection to the
vehicle chassis, resiliently connected to said slide members
and pivotally connected to said pivoting arms through another
transversal rod dispose=_d between the pivoting arms between
said second end and sa.i_d first en.d; said another transversal
rod being pivotally c:o:nnected to the curved portion of the
slide member: through a horizontal rod disposed between said
curved portions of s<.~:i.d slide members, said pivoting arms
being resiliently connected to said curved portion of said
slide members.
– 6 –

CA 02191008 2001-04-20
As embodied and broadly described herein, the invention
further seeks to ~>rovide a suspension assembly for a
snowmobile of=hide comprising:
– two substantial~_y parallel and spaced apart elongated
slide members defining a longitudinal axis, connected
together with transve:r_sa:L=Ly mounted bridge members, each said
slide member having a first curved ending portion and a
second ending portion for connecti_Or1 Of ending wheels;
– two subst=antially parallel elongated pivoting arms,
each having a first end pivotally connected to a respective
one of said slide members at a first connection point spaced
apart said first ending portion and a second end adapted for
connection to a vehicle ~~hassis;
– a fir:>t transversal. rod, adapted for connection to the
vehicle chassis, resi:l..ieni=ly connected to said slide members
and pivotally connectE:d t:o said pivoting arms through another
transversal rod disposed between the pivoting arms between
said second end and said first end; said another transversal
rod being pivotally connected to the curved portion of the
slide member~> through a horizontal rod disposed between said
curved portions of said slide members, said first transversal
rod being connected t:o at least one of said second ending
portion of said s.Lide members.

CA 02191008 2001-04-20
BRIEF DESCRIPTION OF THE DRAWINGS
These and other ob=jects, features and advantages of the
invention, a.s well a~; the invention itself, will become
better understood by reference to the following detailed
description when considered in connection with the
accompanying drawings w;zerein:
FIG. 1 is a side view of a snowmobile, including the
rear suspension system a::cording to the present invention;
FIG. 2 is a perspective view of the rear suspension
system;
FIG. 3 is a side view of a snowmobile vehicle, including
a rear suspension sy;~tem and a longitudinal slide bar,
according to the presen~ invention;
FIG. 3a is a side view of a snowmobile vehicle,
including a .rear suspen.ts ion system and a cable, according to
the present invention;
FIG. 4 is a. sidf, view of a snowmobile, displaying the
displacement of the pi~~~~ting arms, according to the present
invention.
_ g _

CA 02191008 2001-04-20
FIG. 5 is ,~ si.c)e view of a second embodiment of the
travel means;
FIG. 6a is a side view of the bracket;
FIG. 6b is a front: elevational view of a support holding
the bracket;
FIG. 7a is a sic.e elevatic>nal view of the secondary
pivoting arm;
FIG. 7b is a front e7_evational view of a support and the
secondary pivoting arrn attachment;
FIG. 8a is a front elevational view of the pulling belt;
FIG. 8b is a right aide view of the pulling belt;
FIG. 9 i.s a side view of the slide bar;
FIG. 10 i:a a side elevational view of the rear
suspension system in accordance with the present invention
showing possible adjustrnf=nts to the bracket;
_ a

CA 02191008 2001-04-20
FIG. 11 is a side elevational view partially showing the
Weight Transf=er Ciynamz.c C:c>mpensator (WT DC) ;
FIG. 12 is a side ~?l.evational view of the slide bar; and
FIG. 13 is a side v.:LE?W Of a .snowmobile showing different
comfort zones, according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Although the c~isc:l_osed invention may have broad
applicability, it re1_ates primarily to a rear suspension
system for a land vehicle, and more spec ifically to a land
vehicle with a track, ouch as a snowmobile. The following
description will indicav~~ certain items as occurring in pairs
when only one of thf~ pairs is shown in the accompanying
drawings. It is to be understood that the portion of each
pair which is not shown is identical to the illustrated part
and performs the same function as the illustrated item.
Accordingly, it should be noted that like reference numerals
are used throughout t:h~~ attached drawings to designate the
same or similar eLementt> or components.
Referring now to 1=he drawings, Fig. 1 illustrates a
novel rear suspension sy:>t:em 20 for a snowmobile vehicle 10.
– 10 –

CA 02191008 2001-04-20
The vehicle 10 has a front portion 2, with a forwardly
mounted engine therein (not shown), forwardly mounted travel
means 8, and a rear poi=tion 30, comprising seat area 12,
a

steering means 14, a chassis 16, rearwardly mounted travel

means 18 (also krvown as :;=Lidemembers) , and rear suspension
a

20 (see Figure 3) . 7:’he center of the vehicle
of gravity
22

is in the from:. of the vehicle 10 at 22 as
portion 2

indicated.
The rear su~~pens:ion. system 20 of the vehicle is located
adjacent the rear portion of the land vehicle 10, on an
underside of the chas:~is 16 and is attached to the chassis 16
by means of t:wo bori.zonta7_ bars. A first horizontal bar 40 is
attached to an under:;ide of the chassis directly below the
seat area, a:nd a second horizontal bar 50 is attached to an
underside of the chart>is directly below the steering means
14.
In the following description, the terms « proximal » and
« distal » are with re:Ference to t:he front portion 2 of the
vehicle. The rear suspension system 20, as shown in Fig. 2,
comprises rearwardly mo~.ni~ed travel means 18 having proximal
and distal port=ions. The suspension system 20 further
comprises a pair of s_ruclined primary pivoting arms 60, having
proximal endt> 62 and c~ist:al ends 64. The proximal ends to the
– 11 –

CA 02191008 2001-04-20
primary pivoting arm: 62 a.re attached to the second
horizontal bar ‘~0, an~~ the distal portion of the primary
pivoting arms 64 are cormected to a third horizontal bar 70
at distal portion of the rearwardly mounted travel means 18.
Accordingly, the primary pivoting arms are mounted between
the second horizontal har and the third horizontal bar such
that the primary pivoting arms are inclined at an acute angle
with respect to t:.he r_earwardly mounted travel means, when the
vehicle is in a rest position.
The rear suspension system 20 further comprises a
primary suspension me:~n:~ 80, having a proximal end 82 and a
distal end 84. The pro~;i_mal end of the primary suspension
means 82 is attached to t:he first horizontal bar 40 at a rear
portion of_ the undersio.e of the chassis 16, and a distal end
of the primary suspension means f34 is attached to the third
horizontal bar ’70 at: a distal portion of the rearwardly
mounted travel means 1_8. In a preferred embodiment, the
primary suspension mean,, which is mounted between the first
and third horizontal bar:, is inclined at an acute angle with
respect to the rearwa.rdly mounted travel means when the
vehicle is in a rest position. ‘fhe third horizontal bar 70
also holds together th~~ rearward=Ly mounted travel means. In
sum, the third horizc>ntal. bar 70 acts as a support for the
primary pivoting arms 60 and the primary suspension means
– 12 –

CA 02191008 2001-04-20
80, thereby enabling the primary suspension system to control
the displacement of the rearwardly mounted travel means 18.
Furthermore, due to the structure and support of the
suspension system 20 with respect to the vehicle, the stress
and pressure of the primary suspension means 80 is
transferred t:o the chassis 16 at two relatively near points.
Accordingly, in a preferred embodiment, the chassis comprises
a reinforcing plate 400 to reinforce the chassis, as shown in
Fig. 1.
As further illustrated in Figs. 1 and 2,the distal ends
of the primary pivotin~~ arms 64 are attached to the third
horizontal bar 70 by <~n attachment means 66. The distal ends
of the primary pivoti:nc~ arms 64 have an aperture therein of
approximately 0.750 inches for receiving the attachment means
66. Preferably, the attachment means 66 is a bolt for
securing the primary pivoting arm 60 to the third horizontal
bar 70. Each proximal end of the primary pivoting arms 62 has
an aperture of approximately 1.250 inches for receiving the
second horizontal bar 50 at an underside of the chassis, and
for securing the primary pivoting arm thereto. Preferably,
the primary pivoting arms may be comprised of a metallic
material, such as aluminium. However, instead of aluminum, the
primary pivoting arms may be made from another metallic
material having suitable or similar quality. The
– 13 –

CA 02191008 2001-04-20
configuration of the :primary pivoting arms 60 allows the
rearwardly mounted gravel means 18 to remain generally
horizontal when the rE=_arwardly mounted travel means rises
over a bump. The configuration of the primary pivoting arms
also allows the rear suspension to rock backwards during
initial weight transfer caused by hard accelerations.
The distal end of the primary suspension means 80 is
attached to the third horizontal bar at 70, as shown in FIG.
2. More specifically, the distal ends of the primary
suspension means 84 are attached to a bracket 86 which is
further secured to the third horizontal bar 70. The bracket
86 has an aperture therein, for receiving the third
horizontal bar and securing the primary suspension means 80
thereto. In addition, the proximal end of the primary
suspension means 80 has an aperture having a diameter of
approximately 0.875 inches for securing the primary
suspension means 80 to the first horizontal bar 40. Both the
proximal ends 82 and di;~tal ends 84 of the primary suspension
means 80 are attached tc~ the first and third horizontal bars,
40 and 70 respectively, at an interior portion of the
suspension system. Pref:e rably, the primary suspension means
80 are shock absorbers designed to withstand the weight and
suspension of the vehic7_e.
– 14 –

-27-

portion for connection of ending wheels;
– two substantially parallel elongated pivoting arms, each
having a first end pivotally connected to a respective one of
said slide members at a first connection point spaced apart said
first ending portion and a second end adapted for connection
to a vehicle chassis;
– a first transversal rod, adapted for connection to the
vehicle chassis, resiliently connected to said slide members and
pivotally connected to said pivoting arms through another
transversal rod disposed between the pivoting arms between said
second end and said first end; said fourth rod being pivotally
connected to the curved portion of the slide members through a
horizontal rod disposed between said curved portions of said
slide members, said pivoting arms being resiliently connected
to said curved portion of said slide members.

-29-

members at said first connection point.

-30-

with transversally mounted bridge members, each said slide
member having a first curved ending portion and a second ending
portion for connection of ending wheels;
– two substantially parallel elongated pivoting arms, each
having a first end pivotally connected to a respective one of
said slide members at a first connection point spaced apart from
said first ending portion and a second end adapted for
connection to a vehicle chassis;
– a first transversal rod, adapted for connection to the
vehicle chassis, resiliently connected to said slide members and
pivotally connected to said pivoting arms through another
transversal rod disposed between the pivoting arms between said
second end and said first end; said another transversal rod
being pivotally connected to the curved portion of the slide
members through a horizontal rod disposed between said curved
portions of said slide members, said first transversal rod being
connected to at least one of said second ending portion of said
slide members.

connection is provided with an elongated slide bar connected on
a first end to said first rod and on a second end to said slide
member.

connection between said another transversal rod and said horizontal rod is
provided with a
strap.
33