Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FIELD OF THE INVENTION
The presen-t invention pertains to a
conversion unit for converting a wheel-driven tractor
to a track-propelled vehicle.
BACKGROUND OF THE INVENTION
It is very useful on farms to be able -to
convert a land tractor to a snow track-propelled
vehicle so that it can be used in all seasons for
various agricultural operations. Many attempts have
been made to achieve such conversion; however, most
systems require technical knowledge, cannot be effected
at the farm and be easily and quickly attached and
detached to the tractor.
OBJECTS AND STATEMENT OF THE INVENTION
It is an object of the present invention to
provide a conversion unit allowing a land tractor to be
converted quickly to a snow track-propelled vehicle
whenever required. This is achieved by replacing the
front axle and steering wheels of the tractor by an
assembly which may be readily mounted to the tractor by
the farmer himself without difficulty.
The present invention therefore relates to a
conversion unit for converting a wheel-driven -tractor,
having a pair of front steering wheels mounted on a
front axle and a pair of rear driving wheels mounted on
a rear axle, to a track-propelled vehicle, which
comprises:
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A) a front assembly adapted to be mounted to the
front of the tractor i.n replacement of the front axle
and of the steering wheels of the tractor, assembly
including:
i) a transverse beami
ii) at-tachment means for securing the
element to the -tractor;
iii) a tandem-wheel arrangement pivotally
mounted at each end of the transverse beam, each
arrangement including:
a) a pair of telescopically-engaged
wheel supports extending perpendicularly to the
transverse beam;
b) a wheel mounted at opposite ends of
the pair of supports, the width of the wheels being
identical to one another and to -that of an associated
rear driving wheel;
c) tensioning means having one end
mounted to one of the telescopically-engaged supports
and an opposite end mounted to the other of -the
supports; and
B) a pair of endless tracks, each track mounted
over the fron-tmos-t wheel of the tandem-wheel
arrangement and the rear driving wheel associated
therewith; each track displaying inner and outer faces
and two parallel rows of longitudinally spaced guide
means fixed to the inner face, the space be-tween the
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rows corresponding substantially to the width of the
wheels of the tandem~wheel arrangement and that of the
driving wheels.
In a preferred form of the inventlon, the
rear drive wheels of the tractor have projecting tread
portions which are engaged by the guide means to drive
the tracks.
In a further embodiment of the invention,
reinforcing brace means are provided to solidify the
frame of the tractor; these brace means are connected
between the transverse beam and -the rear axle of -the
tractor.
Other objects and further scope of
applicability of the present i.nvention will become
apparent from the detailed description given
hereinafter. It should be understood, however, that
this detailed description, while indicating preferred
embodiments of the inven-tion, is given by way of
illustration only, since various changes and
modifications within the spirit and scope of the
invention will become apparent to those skilled in the
art.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective vlew of a vehicle
equipped with a conversion unit made in accordance with
the present invention;
Fig. 2 is a side elevational view thereof;
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Fig. 3 is a plan view of -the wheel
arrangement over the inner face of the ]ower run of the
track;
Fig. 4 is a perspective view of a guide used
on the inner face of each track; and
Fig. 5 is a perspective view showing a
portion of the conversion unit.
DESCRIPTION OF PREFERRED EMBODIMEN~S
Referring to Figs. 1 and 2, there is shown a
tractor 10 which is equipped with a conversion unit
made in accordance with the present invention so that
it may be used as a snow track-propelled vehicle.
When used for road transportation and farm
work, the tractor is equipped with fron-t s-teering
wheels which are mounted on a front axle in a known
manner (not shown) and which can be steered by means of
a steering wheel 12. The tractor includes rear driving
wheels 14 driven by an engine provided in the front of
the vehicle from a transmission 16 arranged in the
region of the rear axle 18 (see Fig. 3).
The conversion unit for converting this land
tractor to a snow track-propelled vehicle comprises a
front assembly, generally deno-ted 20 in Fig. 5, which,
in turns, comprises a transverse beam 22 to which is
secured a pair of side plates 24 and 26 adapted to be
fixedly attached to the chassis of the tractor by means
of bolts (not shown) engaging appropriate holes 30, 32
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in the plates. A front plate 34 connects the front
ends of the two sides plates 24 and 26 and usually
extends transversely at -the front of the tractor
chassis.
At opposite ends of the transverse beam 22,
tandem-wheel arrangements 36 and 38 pivotally mounted
at 40 and 42, respectively, each comprises, with
reference to tandem arrangement 38, a support struc-ture
which is formed of telescopically engaged beams 44 and
46. The extremity of the support beam 44 comprises a
shaft 48 to which is rotatably connected the frontmost
wheel 50 of the tandem while the opposite extremity of
the other support beam 46 comprises a shaft 52 to which
is rotatably connected the innermost wheel 54 of the
tandem.
Relative movement between the telescopically
engaged elements 44, 46 is accomplished by the
actuation of a hydraulic arrangement of a cylinder 58
and piston 60 which are respectively connected to the
support beams 46 and 44.
The conversion unit also comprises a pair of
endless tracks 62 and 64, each formed of two laterally
spaced rubber bands 62a, 62b and 64a and 64b. The
bands are interconnected by means of L-shaped cleats,
generally designated 68, which are fas-tened to the
outer face of the bands. To the inner face of the
band, and preferably in back-to-back arrangement with
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the cleats 68 are metallic guides 70, each being formed
(see fig. 4) of a base plate 72 and an inverted
V-shaped member 74 tha-t includes a substantially
vertical portion 74a and an inclined reinforcing
portion 74b. Each guide includes a series of holes in
its base plate 72 allowing bolts 76 to fasten both the
cleats 68 and the guides 70 to the bands. The guides
are disposed in two rows which are laterally spaced on
the inner face of the tracks. The rows are separated
from one another by a space which is substantially
equal to the width of the wheels 50 and 54 of the
tandem arrangement and to that of the driving wheels
14.
The wheels of the tandem as well as the
driving wheels all have the same width, preferably 16
inches. Satisfactory results have been obtained with a
conversion unit where the diameter of the tandem wheels
is 16 inches while that of the rear driving wheels is
inches and where the height of the guides is 5
inches.
The hydraulic system 58-60 serves to maintain
the track over the frontmost wheel 50 and the rear
driving wheel 14. On the other hand, the -track is
driven by the guides 70 which engage the lateral
projections 80 of the treads 82 of the drive wheels 14.
To reinforce the structural frame of the
tractor as a result of the installation of the
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conversion unit, a pair of braces ~4 and ~6 is used;
their opposite ends are connected to the transverse
beam 22 of the conversion uni-t and to the rear axle 1
of the tractor.
The steering of the tractor, once converted
into a track-propelled vehicle, does not form part of
the present invention. However, in one preferred
system, the steering is accomplished by the implement
being pulled by the tractor; in this case, an hydraulic
svstem is directly connected between the steering
assembly of the tractor and the implement and it is the
latter which causes the trac-tor to move right or left
as the implement is shifted to left or right. This
allows both endless tracks to be driven while the
vehicle turns. In another known system, the steering
of the vehicle is accomplished by blocking, through the
braking system, operation of the tracks.
Although the invention has been described in
relation to a specific form, it will be evident to a
person skilled in the art that it may be refined and
modified in various ways. For example, the guides can
be made of molded urethane, rubber, or a zinc-aluminum
alloy. It is therefore wished to have it understood
that the present invention should not be limited in
interpretation except by the terms of the following
claims.
