Track assembly for a motorized vehicle (CA)

CA 02728865 2011-01-20

TRACK ASSEMBLY FOR A MOTORIZED VEHICLE
TECHNICAL FIELD OF THE INVENTION
The technical field relates to motorized vehicles and, more particularly to
track
assemblies engageable with a wheel and tire assembly of a motorized vehicle.

BACKGROUND
It is well known that many people drive their vehicles, including trucks, cars
and
other types of vehicles, through all types of terrain and road (or off-road)
conditions.
In difficult driving conditions (collectively referred to as ‘adverse
conditions’) such as
snow, sand, gravel, mud, ice, and the like, wheeled vehicles often have
considerable
propelling difficulties.

Traction (or track) assemblies, or track units, have been developed for
converting
a wheeled driven vehicle, such as trucks, cars, SUV, all-terrain vehicles, and
the like,
into a track-like driven vehicle for improved traction in certain types of
terrain and
driving conditions.

Typically for mounting a track assembly to a wheeled vehicle, the wheels and
tires must be removed on each axle of the vehicle and are replaced by track
assemblies [See for instance U.S. patents nos. 7,131,508; 6,904,986 and
5,607,210]. The installation or removal of the track assemblies must be
carried out in
a specialized facility. Once mounted, the track assemblies cannot be easily
removed.
Furthermore, they are relatively expensive.

There is thus a need for a track assembly for a wheeled vehicle which does not
require removal of the wheels, which is relatively easy and quick to install,
and
effective for improving traction for standard motorized vehicles in adverse
conditions.
BRIEF SUMMARY OF THE INVENTION
It is therefore an aim of the present invention to address the above mentioned
issues.

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According to a general aspect, there is provided a track assembly for a
motorized vehicle having wheels. The track assembly comprises: a longitudinal
endless track belt having an outer surface and an inner surface; a mounting
structure
to mount the longitudinal endless track belt to the vehicle, the mounting
structure
including at least one driving gear disposed externally to the longitudinal
endless
track belt and configured to frictionally engaged an outer surface of one of
the
motorized vehicle wheels, the at least one driving gear being drivingly
connected
with the longitudinal endless track belt for transmitting power thereto, each
one of the
at least one driving gear having a rotation axis, a plurality of elongated
traction bars
extending substantially parallel and circumferentially to the rotation axis,
and
apertured ends, the elongated traction bars being spaced-apart from one
another
and defining therebetween channels allowing granular and liquid materials to
flow
inwardly towards the rotation axis, and outwardly of the at least one driving
gear
through the apertured ends; and inner wheels in contact with the inner surface
of the
longitudinal endless track belt.

In an embodiment, the mounting structure comprises two driving gears located
respectively forwardly and rearwardly of the engageable motorized vehicle
wheel
and the apertured ends extending radially from the rotation axis.

In an embodiment, the at least one driving gear comprises a radial support
connecting an axle of the driving gear and the traction bars and maintaining
the
traction bars in a radially spaced-apart relationship and each one of the
traction bars
having two opposed ends unattached to the axle and thereby defining the
apertured
ends of the at least one driving gear.

In an embodiment, the at least one driving gear is drivingly connected through
meshed linkages with the longitudinal endless track belt for transmitting
power
thereto without slippage.

The longitudinal endless track belt can rotate in the rotational direction of
the
motorized vehicle wheel when actuated.

In an embodiment, the at least one driving gear comprises a plurality of
traction
bar units, each one of the traction bar units including at least two traction
bars, the
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traction bar units being spaced-apart from one another and defining a channel
therebetween, the elongated track belt being in meshing engagement with the
channels defined between two circumferentially consecutive traction bar units.

A track assembly can comprise at least one attachment chain having a first end
secured to the mounting structure and a second end securable to the motorized
vehicle. The second end can be securable to the wheel axle.

In an embodiment, the mounting structure comprises two spaced-apart side
guiding plates including rollers for receiving the vehicle wheel therebetween
and
being mounted externally of the longitudinal endless track belt. The distance
between the side guiding plates can be adjustable.

According to another general aspect, there is provided a motorized vehicle
including four detachable track assemblies to support the vehicle onto a
ground
surface and having four wheels, each one of the track assemblies comprising: a
frame; a longitudinal endless track belt movably mounted to the frame; inner
wheels
rotatably mounted to the frame and in contact with an inner surface of the
longitudinal endless track belt; at least two driving gears disposed
externally to the
longitudinal endless track belt and being in frictional driving engagement
with one of
the four motorized vehicle wheels for rotation therewith, located above the
longitudinal endless track belt and drivingly connected to the endless track
belt for
transmitting motion thereto, each one of the driving gears having a central
rotation
axis with a plurality of elongated traction bars extending substantially
parallel and
circumferentially to the central rotation axis, the elongated traction bars
being radially
spaced-apart from the rotation axis and from one another.

In an embodiment, the driving gears have open ends and/or are drivingly meshed
with the longitudinal endless track belt.

In an embodiment, the driving gears comprise a radial support connecting an
axle
of the driving gears and the traction bars and maintaining the traction bars
in a
radially spaced-apart relationship and each one of the traction bars having
two
opposed ends unattached to the axle and thereby defining the open ends of the
driving gears.

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In an embodiment, the driving gears comprise a plurality of traction bar
units,
each one of the traction bar units including at least two traction bars, the
traction bar
units being spaced-apart from one another and defining a channel therebetween,
the
elongated track belt being in meshing engagement with the channels defined
between two circumferentially consecutive traction bar units.

Each one of the track assemblies can comprise at least one attachment chain
having a first end secured to the mounting structure and a second end
securable to
the motorized vehicle.

In an embodiment, the mounting structure comprises two spaced-apart side
guiding plates including rollers for receiving the vehicle wheel therebetween
and
being mounted externally of the longitudinal endless track belt.

According to still another general aspect, there is provided a driving gear
for
transferring power from a vehicle wheel to a track of a vehicle track
assembly, the
driving gear comprising a body in the shape of a hollow cylinder having two
spaced-
apart open ends, a central axle and a plurality of longitudinally oriented,
and
regularly circumferentially interspaced traction bars defining the cylindrical
shape
and being adapted for receiving traction from the vehicle wheel, and a
plurality of
channels interspersed between corresponding ones of the traction bars, the
channels being shaped for evacuating snow from the track inside the hollow
cylinder
and out the two open ends.

In an embodiment, the driving gear comprises a radial support connecting the
axle and the traction bars and maintaining the traction bars in a radially
spaced-apart
relationship and each one of the traction bars having two opposed ends
unattached
to the axle and thereby defining the open ends of the driving gears.

In an embodiment, the driving gear comprises a plurality of traction bar
units,
each one of the traction bar units including at least two traction bars, the
traction bar
units being spaced-apart from one another and defining the interspersed
channels
therebetween.

According to a further general aspect, there is provided a method of mounting
at
least one vehicle track assembly to a vehicle, the method comprising laying
the at
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least one vehicle track assembly on the ground, attaching at least one ramp to
one
end of each one of the at least one vehicle track assembly, displacing the
vehicle for
a wheel thereof to mount the at least one ramp and drop into an operative
position in
the at least one vehicle track assembly, and removing the at least one ramp.

In an embodiment, the at least one ramp comprises an attachment bar mating
and engageable with a channel defined in a driving gear of the at least one
track
assembly for preventing rotation of the driving gear.

In an embodiment, attaching the at least one ramp comprises inserting a first
attachment male member of the at least one ramp in a mating slot of the at
least one
track assembly and inserting an attachment bar of the at least one ramp in a
mating
channel defined in a driving gear of the at least one track assembly and
between two
circumferentially consecutive traction bars of the at least one track assembly
for
preventing rotation of the driving gear.

According to another general aspect, there is provided a track unit kit for a
motorized vehicle having a plurality of wheels, the track unit kit comprising:
a track
assembly including a frame, a longitudinal endless track belt movably mounted
to the
frame, inner wheels rotatably mounted to the frame and in contact with an
inner
surface of the longitudinal endless track belt, and at least two driving gears
disposed
externally to the longitudinal endless track belt, located above the
longitudinal
endless track belt and drivingly connected to the endless track belt for
transmitting
motion thereto, each one of the driving gears having a central rotation axis
with a
plurality of elongated traction bars extending substantially parallel and
circumferentially to the central rotation axis, the elongated traction bars
being radially
spaced-apart from the rotation axis and from one another for defining channels
therebetween; and a ramp for mounting and dismounting the vehicle wheels from
the
track assembly above the endless track belt and between the driving gears, the
ramp
having an attachment bar mating and engageable with one of the channels
defined
in the driving gears and preventing rotation of the driving gears during
mounting and
dismounting the vehicle wheels from the track assembly .

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In an embodiment, the frame of the track assembly comprises a slot defined
therein and the ramp comprises an attachment male member removably insertable
in the slot for attaching the ramp to the track assembly .

In this specification, the term « vehicle wheel » is intended to mean the wheel
of the
vehicle including or not the tire surrounding the wheel.

BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side elevation view of a motorized vehicle including track
assemblies in
accordance with an embodiment;

Fig. 2 is a perspective view of one of the track assemblies shown in Fig. 1
including an endless track belt;

Fig. 3 is a perspective view of the track assembly shown in Fig. 2 wherein the
endless track belt is removed;

Fig. 4 is a side elevation view of the track assembly shown in Fig. 2
including the
endless track belt and wherein an inside mounting plate is removed; and

Fig. 5 is a perspective view of a track driving wheel of the track assembly
shown
in Fig. 2 in accordance with an embodiment; and

Fig. 6 is top plan view of the track driving wheel shown in Fig. 5.

It will be noted that throughout the appended drawings, like features are
identified
by like reference numerals.

DETAILED DESCRIPTION
A track assembly 20 adapted to be retrofitted to a motorized vehicle 22 in
accordance with an embodiment will now be described in details with reference
to
the appended drawings.

Fig. 1 shows a motorized vehicle 22 and, more particularly a pick-up truck,
including a body and four track assemblies 20 (only two are shown) arranged in
a
plane adjacent to each side of the vehicle 22. The four track assemblies 20 of
the
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motorized vehicle 22 are identical and are mounted to the conventional wheel
and
tire assemblies 26 of the motorized vehicle 22. Only one track assembly 20,
visible in
Fig. 1, will be described hereinbelow.

As mentioned above, the terminology « vehicle wheel 26 » will be used herein to
designate the vehicle wheel including or not its surrounding tire.

Referring to Fig. 2, it will be seen that the track assembly 20 includes a
longitudinal endless track belt 30 and a mounting structure 32 to mount the
endless
track belt 30 to the vehicle 22. The mounting structure 32 includes, amongst
others,
a pair of track driving gears 34 disposed on opposite sides of the rotation
axis of the
vehicle wheel 26, a plurality of inner idler wheels 36 disposed inside the
longitudinal
endless track belt 30, and supports to interconnect the wheels 34, 36, as it
will be
described hereinbelow. As it can be seen from Figs. 1, 2, and 4, the vehicle
wheel 26
and the driving gears 34 are external to endless track belt 30. The endless
track belt
30 is wounded around the inner idler wheels 36 while the vehicle wheel 26 and
the
driving gears 34 are located outside the loop defined by endless track belt
30.

Referring to Figs. 2 and 4, the endless track belt 30 is made of an
elastomeric
material and has an outer surface 38 for contact with the ground and an inner
surface 40. The outer surface 38 is provided with transversal lugs 42 and is
adapted
to engage with the driving gears 34. More particularly, in the embodiment
shown, the
driving gears 34 meshingly engage with the equidistant transversal lugs 42.
However, it is appreciated that in an alternative embodiment (not shown), the
endless track belt 30 can be provided with equidistant longitudinally spaced-
apart
openings separated by bridging webs for engagement with the driving gears 34.

The mounting structure 32 further includes an inside mounting plate 44 and
an outside mounting plate 46, spaced-apart from the inside mounting plate 44.
The
driving gears 34 and the inner wheels are interconnected with the inside and
outside
mounting plates 44, 46, with the driving gears 34 being disposed externally to
track
belt 30. As it will be described in further details below, the inside and
outside
mounting plates 44, 46 support the axle 48 of the driving gears 34 and the
inner idler
wheels 36 through a plurality of supports 50, 52 extending parallel to one
another
and extending between the inside and outside mounting plates 44, 46. More
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particularly, each of the driving gears 34 is rotatably mounted to support 52
which
connect the inside and outside mounting plates 44, 46. The support 52 is
concentric
with the axle 48. The driving gears 34 are rotatable about the support 52.

The track assembly 20 further includes two spaced-apart cover plates 53,
extending above the track belt 30, on the front and the rear end of the track
assembly 20 and between the inside and outside mounting plates 44, 46. It also
includes a central cover plate 55 extending between both driving gears 34. The
cover plates 53, 55 prevent access to the track belt 30 and reduce the amount
of
granular material in contact with the track belt 30 and the driving gears 34
during
operation.

Referring now to Figs. 3 and 4, the configuration of the inner idler wheels 36
will be described in further details. The endless track belt 30 is supported
by a
plurality of idler wheel rows, connected together through the inside and
outside
mounting plates 44, 46. Each one of the inner idler wheels 36 has a peripheral
portion in contact with the inner surface of the track belt 30 and rotates
therewith.
The idler wheels 36 close to the track belt ends have a larger diameter than
the
internal idler wheels 36 as shown in Fig. 4. More particularly, the last and
the next-to-
last front and rear idler wheel rows 54 include idler wheels 36 of larger
diameter than
the idler wheel rows extending therebetween.

The inner idler wheels 36 are also rotatably mounted on supports 50 which
connect the inside and outside mounting plates 44, 46 and are secured thereto.
In
the embodiment shown, each support 50 has four spaced-apart idler wheels 36
rotatably mounted thereto. It is appreciated that in alternative embodiments,
any
number of inner idler wheels 36 can be rotatably mounted to each support 50.
Furthermore, the idler wheels 36 of two consecutive rows are disposed in a
staggered relationship. However, it is appreciated that the idler wheels 36 of
consecutive rows can be the same planes, i.e. aligned with one another.

Referring now simultaneously to Figs. 5 and 6, it will be seen that driving
gears 34 have a body 56 in the shape of a hollow cylinder with two spaced-
apart
open ends 58, a central axle 48, and a plurality of elongated and
substantially
regularly circumferentially interspaced traction bars 60. In other words, the
traction
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bars 60 are arranged in a circle around the driving gear axle 48. The traction
bars 60
define the cylindrical shape of the driving gears 34 and extend substantially
parallel
to the axle 48. The traction bars 60 are divided in equidistant traction bar
units 62
wherein each unit 62 includes three traction bars 60, spaced-apart from one
another.
Each traction bar 60 of one unit 62 are connected at their ends. Channels or
slots
64, 65 are defined between adjacent (or circumferentially consecutive)
traction bars
60 in the traction bar unit 62 and between adjacent (or circumferentially
consecutive)
traction bar units 62. The channels 65 between two consecutive traction bar
units 62
are larger than the channels 64 between two consecutive traction bars 65
within one
traction bar unit 62. The channels 62 are shaped for evacuating granular and
liquid
materials such as snow, sand, gravel, mud, ice, and the like from the vehicle
tire and
the track belt 30 inside the hollow cylinder of the driving gears 34 and then
out the
two open ends 58 of the driving gears 34. The granular and liquid materials
are
extruded inside and then outwardly of the driving gears 34 to reduce slippage
and
congestion of driving gears 34. In the embodiment shown, the ends of the
traction
bars 60 are unattached to the axle 48.

The traction bars 60 are connected to the axle 48 through a radial support 66
which extends substantially centrally of the traction bars 60. The radial
support 66
maintains the elongated traction bars 60 in a radially spaced-apart
relationship with
the axle 48.

As mentioned above, the driving gears 34 are located respectively forwardly
and
rearwardly of the motorized vehicle wheels 26, and the traction bars 60 are
adapted
for receiving traction from the vehicle wheels 26. In the operative
configuration, the
vehicle wheel 26 is seated between the two driving gears 34.

For reduced slippage during rotational frictional engagement with the vehicle
wheels 26 and, more particularly with the surrounding tire (if any), an outer
edge of
the traction bar 60 includes a plurality of lugs 68 integrally formed and
separated by
indentations, i.e. a plurality of projections that help to provide traction.
In a traction
bar unit 62, two successive rows of lugs 68 are arranged in a staggered
relationship
to promote traction. The lugs 68 define the wheel (or tire) contacting surface
of the
driving gears 34.

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In an alternative embodiment, the open ends 58 could be apertured ends, i.e.
ends having apertures defined therein allowing the granular and liquid
materials to
flow outwardly of the driving gears 34. For instance and without being
limitative, the
driving gears 34 can include at least two spaced-apart radial supports having
apertures defined therein and secured to the traction bars 60 close to their
ends and
to the support 52. In another alternative embodiment, spaced-apart rods can
attach
the ends of the traction bars 60 to the axle 48.

In an alternative embodiment, the hollow body of the driving gears 34 can
include one or several protruding stem(s) which act as extrusion members for
breaking agglomeration of granular material and pushing the granular material
outside the driving gears 34 through the open or apertured ends.

It is appreciated that the number and configuration of traction bars 60 and
traction bar units 62 can vary.

As mentioned above, the hollow shape of the driving gears 34 and more
particularly channels 64, 65 allow the evacuation of granular and liquid
materials
such as snow, sand, gravel, mud, ice, and the like from the vehicle tire and
the track
belt 30 inside the hollow cylinder of the driving gears 34 and then out the
two open
ends 58 of the driving gears 34. The granular and liquid materials are
extruded
inside and then outwardly of the driving gears 34 to reduce slippage and
congestion
of driving gears 34.

The traction bar units 62 cooperate with transversal lugs 42 of the endless
track belt 30 for propelling the vehicle 22. More particularly, the traction
bar units 62
are in driving engagement with the lugs 42, i.e. the traction bar units 62 are
inserted
between two consecutive transversal lugs 42 and apply pressure to the latter
to
rotate the track belt 30. The traction bar units 62 are spaced out so that the
distance
between two consecutive traction bar units 62 spans the distance separating
consecutive transversal lugs 42, in a meshing engagement, in such a way as to
drive
the endless track belt 30.

As stated hereinabove, the track assembly 20 is provided with an external
gearing, i.e. the track driving gears 34 are located externally of endless
track belt 30.
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The endless track belt 30 has a plurality of equidistant transversal lugs 42,
which
ensure a positive engagement with the traction bars 60 provided on the outer
circumference of track driving gears 34. In operation, the wheels and tires 26
of the
vehicle 22 are in rotational frictional engagement with the track driving
gears 34 and
the rotational movement of the wheels and tires 26 is transmitted to the track
driving
gears 34. The track driving gears 34 are in meshing or gearing engagement with
the
track belt 30 for transmitting rotational motion.

As it will be easily understood by one skilled in the art, the driving gear 34
can
cooperate with either transversal lugs 42 of the endless track belt 30 or with
bridging
webs, whichever the endless track belt 30 includes.

Thus, the engine of the motorized vehicle 22 drives the vehicle wheel 26 in
rotation. The vehicle wheel 26 thus drives both track driving gears 34 in
rotation by
frictional engagement between an outer surface of the vehicle wheel 26 (or
tire, if
any) and the elongated traction bars 60 of the driving gears 34. The track
driving
gears 34 drive the endless track belt 30 in rotation by the meshing engagement
of
the elongated traction bars 60 with the transversal lugs 42 of the endless
track belt
30. It is further to be understood that the transversal lugs 42 on the
external
circumference surface 38 of the endless track belt 30 also exert a positive
mechanical connection with the underlying ground surface that contributes to
propel
the motorized vehicle 22.

The track assembly 20 further includes two spaced-apart side guiding plates
70 including rollers 72 for receiving the vehicle wheel 26 therebetween in an
operative configuration. The side guiding plates 70 are mounted externally of
the
longitudinal endless track belt 30. The distance between the two side guiding
plates
70 substantially corresponds to the width of the vehicle wheel 26 (including
its tire, if
any). In the embodiment shown, the side guiding plates 70 have a substantially
annular shape. However, it is appreciated that the shape can vary in
alternative
embodiments (not shown). The side guiding plates 70 ensure that the vehicle
wheel
26 remains on the track assembly 20 when mounted thereto and prevents side
slippage from the track assembly 20. The rollers 72 are rotatably mounted in
apertures defined in the side guiding plates 70 and are oriented in a
substantially
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radial configuration with the vehicle wheel 26. They are positioned to abut
the lateral
faces of the vehicle wheel 26 when the latter is mounted to the track assembly
20,
which lower friction and simultaneously guide the vehicle wheel 26 and prevent
side
slippage. In the embodiment shown, each one of the side guiding plates 70
include
five rollers 72; however, it is appreciated that in alternative embodiments
(not
shown), the side guiding plates 70 can include more or less rollers. In
another
alternative embodiment, the side guiding plates 70 can be roller free. In a
further
alternative embodiment, the track assembly 20 can be side guiding plate free.

The track assembly 20 can be mounted to vehicle wheel 26 of various
diameters. To adapt the track assembly 20 to the size of the wheel 26, the
distance
between the two side guiding plates 70 can be adjusted. In the embodiment
shown
in Fig. 2, the side guiding plates 70 are connected together through
transversal bars
74 having a plurality of apertures 76 defined therein and slidable relatively
to one
another. Therefore, the distance between the two side guiding plates 70 can be
adjusted in accordance with the width of the vehicle wheel 26 and secured in
the
selected configuration by inserting fasteners in the apertures 76 in registry.
It is
appreciated that the mechanism for adjusting and securing the side guiding
plate
configuration can differ from the one shown. Furthermore, in an alternative
embodiment, the entire track assembly width can be adjustable instead of
solely the
distance between the two side guiding plates 70.

The track assembly 20 can be secured to the vehicle 22 and/or the vehicle
wheel
26. Referring back to Fig. 1, there is shown that the track assembly 20
includes an
attachment chain 78 having a first end secured to the mounting structure 32,
substantially centrally thereof and on the outer side of the track assembly
20, and a
second opposed end secured to the motorized vehicle 22. In the embodiment
shown
and in the operative configuration of the track assembly 20, the second end is
secured to the wheel axle 80. When attached to the vehicle 22, the chain 78 is
substantially taut. When removing the vehicle wheel 26 from the track assembly
20,
the second end of the attachment chain 78 can be unsecured.

Other embodiments can be foreseen for securing the track assembly 20 to the
vehicle 22. In another non-limitative embodiment, the attachment chain 78 can
be
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located on the inner side of the track assembly 20 and the second end can be
secured to the vehicle frame. In a further non-limitative embodiment, two
attachment
chains can be used to secure the track assembly 20 to the vehicle frame. A
first
attachment chain can be secured forwardly of the vehicle wheel 26 and a second
attachment chain can be secured rearwardly of the vehicle wheel 26.

In another embodiment (not shown), the track assembly 20 can include a belt
(not shown) which surrounds the vehicle wheel 26 when mounted to the track
assembly 20 in the operative configuration. The belt can have a plurality of
rollers for
reducing friction between the belt and the wheel 26 during operation. As the
attachment chain 78 and the side guiding plates 70, the belt secures the
vehicle
wheel 26 to the track assembly 20 in the operative configuration and prevents
side
slippage from the track assembly 20.

In another embodiment (not shown), the track assembly 20 can include
attachment bars (not shown) which extend from the mounting structure 32 and
abut
an upper surface of the vehicle wheel 26 when mounted to the track assembly 20
in
the operative configuration. For instance and without being limitative, the
attachment
bars can have an inverted Y shape with two arms abutting the upper surface of
the
vehicle wheel 26. The attachment bars can have rollers for reducing friction
between
the latter and the wheel 26 during operation. The attachment bars secure the
vehicle
wheel 26 to the track assembly 20 in the operative configuration and prevent
side
slippage from the track assembly 20. In an embodiment, the length of the
attachment
bars can be adjustable through a slidable structure. Therefore, the length of
the
attachment bars can be adjusted in accordance with the diameter of the vehicle
wheel 26.

As it will be easily understood by one skilled in the art upon inspection of
Figs.