Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
SB~
SUSPENSION AND STEERING ASSE:MBLY FOR SNOWI~OBILE
This invention relates to a suspension and steering
assembly for a snowmobile having at least one ski for supporting a
fron-t half of i-ts body and also for s-teering the snowmobile.
Generally, a snowmobile includes full tractor treads
supporting a rear portion of its body and also for clriving the
snowmobile, and one or two skis for supporting a front portion of
its body and also for steering the snowmobile. When a leaf spring
is used as an element of a suspension and steering assembly con~
necting the ski to the body of the snowmobile, it is impossible to
obtain vertical displacements of a large value. Thus a coil spring
and a shock absorber are mounted coaxally to provide a hollow strut
member that can be expanded and compressed considerably in an axial
direction relative to the ski in most of the snowmobiles now in use.
The aforesaid suspension and steering assembly is substan-
tially similar in construction to that of motorcycles. However,
unlike a motorcycle which is in contact with the ~round at one point
on the periphery of a tire of each wheel, a snowmobile is in contact
at the undersurface of each ski with the surface of snow. The under
surface of each ski is in contact with the surface of snow in a
wide area ~xtending from front to rear, so that a high torque is
required to turn the ski on the snow. When the suspension and
steering assembly includes a single strut member, a torsional moment
of a high magnitude would be exerted on the strut member and a high
force would be exerted on the connection between the assembly and
the ski. This would result in an increase in cost or provide a
potential source of trouble.
: '' ', ~ .
~s~
~ lso when the ski is pivotally connected to the lower end
of the strut memher, the ski may move freely about the lower end
of the strut member and may not be fixed. In moving on ~he sura~
of snow which is irregular, the ski may tend to move in violen~
pitching motion in a vertical plane and impair the riding comort
of riders of the snowmobile. An added disadvantage is that in
transporting the snowmobile it is necessary to fix the skis by
using additional means which is troublesome.
The aforesaid disadvantages of the prior art are obviated
by the present invention. Accordingly, the invention has as its
object the provision of a suspension and steering assembly for a
snowmobile which is novel and enables a torque to be transmitted
smoothly to its ski when the snowmobile is steered and permits the
ski to be suitably fixed during operation, so that the assembly can
suitably absorb shock with respect to the pitching movement, the
vertical movement and the turning movement pf the ski during
operation.
According to the invention, there is provided a suspension
and steering assembly for a snowmobile including at least one ski
for supporting a front portion of its body and also for steering
the sno~nobile, comprising strut means including a first or inner
strut member and a second or outer strut member telescopically slid-
ing one into the other, spring means operative to urge the two strut
members to slide out of each other, shock absorber means pivotally
connected at one end to the ski and at the other end to the second
or outer strut member, means for supporting the second or outer
strut member for rotational movement while preventing its axial
movement and its lateral movement, and steering arm means fixedly
~s~
secured to the second or outer strut member for rotating the strut
means about its own axis when a steering gear is actuated,wherein
the first or inner strut member i5 pivotally connected at its lower
end to the surface of the ski.
Addltional and other objec~s, Eeatures and advan-tages of
the invention will become evident from the descr.ip-tion se~ ~orth
hereinafter when considered in conjunction with the accomp~nying
drawing, wherein:
The single drawing is side view, with certain parts being
shown in section, of the suspension and steering assembly comprising
one embodiment o~ the invention.
A preferred embodiment of the invention will now be de-
scribed by referring to the drawing wherein a body 10 and a ski 7
are connected to each other by strut means 4 including a first
strut member (inner member) 1 and a second strut member (outer
member) 2,one telescopically slida~le into the other, and a housing
3 connected to the upper end of the second strut member (outer
member) 2. A shock absorber S is connected at one end to the second
strut member (outer member) 2 and at the other end to the ski 7 to
extend obliquely.
The first strut member ~inner member) 1 is connected at
its lower end to the ski 7 through a ski mounting member 6 for
pivotal movement about a horizontal shaft extending through the
mounting member 6. A coil spring 8 is mounted in the strut means 4
coaxially therewith and maintained in pressing engagement with the
lower end of the first strut member (inner member) 1 at its lower
end and with the upper end of the housing 3 at its upper end for
urging the strut means 4 to move to a telescopically expanded
-3-
'~'' ~ -
.
~ ..
' , ' ~ ' '
$8~8
position by its biasing force.
The second strut member (outer member) 2 is supported by
the body 10 through a support member 9 for rotation about its o~n
axis while being prevented from movlny axially and lakerall~ wi~h
respect to the body 10. The second strut member (outer member) ~
has fitted over its outer periphery and secured thereto an annular
steering arm 11 which i9 adapted to be rotated about the axis o~
the strut means 4 by a steering gear, not shown. The steering arm
11 is formed with openings 11a and 11b in two projections which
respectively receive therein a steering rod connected to the steering
gear and one end of a tie rod connected to a steering arm of the
other suspension and steering assen~ly for the snowmobile.
Secured to the lower end of the second strut member (outer
member) 2 is a connector 12 for pivotally supporting the upper end
of the shock absorber 5 which is formed at its side with a bearing
portion 12a having a substantlal length in the horizontal direction.
The shock absorber 5 is formed ~at its upper end with a fork to
provide brackets 5a having a connectlng bolt connected thereto at
opposite ends and extending through the bearing portion 12a, so that
the shock absorber 5 can move freely in pivotal movement while being
prevented from being twisted by an external force.
The shock absorber 5 is connected at its lower end to
the surface of the ski 7 at a point 13 disposed forwardly of the
ski mounting member 6 at which the strut means 4 is pivotally con-
nected to the ski 7. The lower end of the shock absorber 5 is
also pivotally supported by a horizontal shaft on the ski 7.
From the foregoingjit will be appreciated that the body 10 is
stably supported by the ski 7 through the strut means 4 having the
. ~...........
.-:
~2~
spring 8 mounted therein and capable of telescopically expanding
and contracting, and the shock absorber 5 pivotally connected ko
the ski 7 and the strut means 4 and extending obliquely rom ~he
strut means 4. By khis arrangement, the ski 7 can also be inclined
to conform to the slope of the surface of snow to perrnit -the under-
surface of the ski to be maintained in contact with the snow at all
times, and the dist~nce between the body of the snowmobile and the
ski can be adjusted by the telescopic sliding movement of the
members 1 and 2 of the strut means 4. The provision of the shock
absorber 5 has the effects of absorbing shock which might otherwise
be applied to the body of the snowmobile by the sudden pitching
movement or vertical movement of the ski.
In steering the snowmobile, the steering gear is manipulat-
ed to rotate the steering arm 11. This turns the strut means 4 and
at the same time rotates the shock absorber 5 about the^axis of
the strut means 4, so that a turning torque is transmitted to the
ski 7 with leverage or high magnitude. This avoids application of
a force of high magnitude to the connections between the lower end
of the strut means 4 and the lower end of the shock absorber 5 and
the surface of the ski 7.
The strut means 4 is normally somewhat inclined with respect
to the ski 7 as shown, and the shock absorber 5 has its length
varied when the ski 7 turns in a horizontal plane. Thus the shock
absorber 5 has the effect of braking the turning movement of the
ski in addition to the pitching movement and vertical movement there-
of,thereby enabling stable and smooth travel of the snowmobile. In
the embodiment shown and described hereinabove, the shock absorber
is connected at its lower end to the surface of the ski at a point
.. .. .
.
8~
forwardly of the mounting member for supporting the strut means on
the surface of the ski. However, the invention is not limited to
this specific position of the shock absorber and that the shock
absorber may be disposed rearwardly of the strut means wi~h the
same effects.
According to the invention, the stability of the ski
travelling on the snow can be enhanced and the pi.tching movement,
vertical movement and turning movement of the ski can be suitably
braked and shock applied to the ski during these movements can be
absorbed, to thereby increase riding comfort of the riders by
enabling the snowmobile to travel smoothly and stably. No great
stresses are produced in the component parts of the snowmobile, so
that the safety of travel is ensured.
