Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Title of the Invention
Traction chain assembly for an endless traction band and method for installing
same.
Field on the Invention
This invention relates to traction chains for a vehicle. More particularly,
the present
invention relates to a traction chain assembly to be used on endless track and
to a method
to install the assembly on an endless track.
Background of the Invention
Numerous types of vehicles are frequently used in terrain in which it is
difficult for
pneumatic tires to operate. Both military vehicles, such as tanks and
amphibious vehicles,
and civilian vehicles, such as tractors and recreational vehicles, are
sometime utilized on
terrains which are very soft, for example sand surfaces. Pneumatic tires are
not capable of
efficient operation on such soft surfaces, as they tend to burrow into the
surface, rather
than riding across the surface.
Endless track vehicles have been developed for use on terrains in which
pneumatic-tired
vehicles are impractical. See for example U.S. Patents 3,361,488 (Ohrn et al),
3,688,858
(Jespersen), 3,734,577 (Snellman) and 3,955,855 (Massieon et al). In many
types of
terrain these vehicles provide improved performance relative to the
performance of
pneumatic-tired vehicles; still, difficulties are encountered with existing
endless track
vehicles.
Originally, such tracks were made of a plurality of metal links or shoes
pivotally attached
to each other to form an endless track which are very heavy, cause serious
damage to
roads and other surfaces on which they run and result in an uncomfortable ride
for the
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passengers. See for example U.S. Patents 2,823,082 (Bauer) and 4,530,546
(Meisel, Jr.).
Heavier vehicles still use metal tracks.
The above-referenced conventional tracks have the disadvantages of being noisy
and
vibration prone, not sufficiently durable and/or not usable on road surfaces.
This is
because of the conventional configurations and use of metal parts.
Accordingly,
substantial efforts have been made to construct quieter, smoother operating
and more
durable tracks for tracked vehicles.
A need has developed for a form of vehicle appropriate for both normal highway
use and
off road use over snow-covered, very uneven, or muddy terrain. There is
significant need
for such a vehicle not only during armed conflicts but also following natural
emergencies
(snow and wind storms, floods, etc.), and such vehicles are at present
particularly needed
in developing countries. Unfortunately, almost all available automotive
vehicles require
infrastructure (paved highways, bridges, etc.) for practical operation, and
the developing
countries are decades away from having the necessary infrastructure for such
conventional vehicles. Further, most load-carrying off-road vehicles presently
in use have
either very large wheels or very cumbersome tracks which are heavy, stow
moving, and
inappropriate for use on paved roads at normal highway speeds.
Rubber endless tracks have become popular due to an increase in construction
in urban
areas where vehicles having tracks must drive on the pavement and because
there is a
demand for tow soil compaction farming. With the combination of rubber
technology and
a tremendous amount of trial and error, various types of rubber tracks are now
available
in the industry. They are used on excavators, dump carriers, boring machines,
combines,
tractors, and the like See for example U.S. Patents 5,279,378 (Graiwey & al)
and
6,267,458 (Hansen et al). Most of them operate on the job site only and are
transported
between sites by trucks or trailers. To eliminate the inconvenience of
transporting the
vehicle between job sites, a vehicle which can operate both on public roads at
normal
speeds and in off-road construction environments is required. However, such a
vehicle
will have to be constructed so as to provide little damage to the pavement,
include less
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vibration and noise, and operate with less maintenance and lubrication.
Furthermore,
vibrations to be transmitted to occupants are mitigated and paved roads are
not
significantly damaged.
A number of hybrid tracks have been proposed where the links or shoes are made
of
metal which is provided with a rubber cover or insert. See for example U.S.
Patents
2,359,586 (Sayler), 2,369,130 (Benson), 2,409,502 (Leguillon et al), 3,148,921
(Batur et
al), 4,109,971 (Black et al), 4,359,248 (Kortering) and 4,588,233 (DenBesten).
[NOTE: As used herein, the term "rubber" relates to any elastic and primarily
non-
metallic materials such as rubber, elastomers, or combinations thereof used in
the
manufacture of endless tracks].
Most rubber tracks are formed around a basic carcass or belt. The carcass
includes an
endless belt-shaped rubber-like elastic member, a number of core bars (usually
of metal)
embedded therein and aligned in the longitudinal direction thereof and
extending in
traverse directions thereof, and steel cords (tension-resistant members)
embedded in the
endless elastic member to surround the core bars circumferentially outwardly.
See for
example U.S. Patents 4,904,030 (Ono), 5,295,741 (Togashi et al), 5,511,869
(Edwards et
al) and 6,241,327 (Gleasman).
Some have suggested the construction of endless rubber tracks using a
plurality of
interconnected polymeric modules. See for example U.S. Patents 4,861,120
(Edwards et
al) 5,005,922 (Edwards et al).
Terrain-contacting lugs are formed integral with the exterior surface of this
basic belt
element. Known rubber tracks include large lugs having a variety of well-known
orientations, e.g., formed generally perpendicular to the track axis, or at an
angle to the
track axis, or in a chevron or modified-chevron design. These latter special
tracks also
include interior lugs or horns for maintaining the track in alignment as it
travels over the
circumferences of the rubber-tired wheels, such lugs being located either in
the centre of
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the interior surface of the track (for designs appropriate for fitting between
the tires of
dual-wheels) or in two aligned rows near the outside edges of the track (for
receiving a
single tire there between). See for example U.S. Patent 5,447,365 (Muramatsu &
al) and
5,540,489 (Muramatsu & al).
The tracks are carried by a plurality of rotating elements (wheels, sprockets,
etc...)
mounted on the track-laying vehicle, the tracks being maintained in
circumferential
contact with these rotating elements and being driven thereby (or, in the case
of trailer-
like non-driven vehicles, being supported for rotation thereon).
However, the advent of rubber track in the field of military and other heavy
vehicles has
created another problem. Metallic tracks of the prior art had many
disadvantages that
rubber tracks have solved such as damage to paved roads and noise. Metallic
tracks had
however the advantage to have a better grip on icy and other flat and slippery
surfaces.
Indeed, the metallic cleats of these metallic tracks could "eat" into the ice
in order to
move. Rubber tracks don't have cleats and their ground-engaging lugs cannot
"eat" into
ice and thus, present some difficulties when driven on icy surfaces.
Hence, there is a need for a device that can improve the traction of endless
rubber tracks
especially when the vehicle is traveling on icy surfaces. Such a device should
be easily
and rapidly installed and removed from the rubber track.
Obiect of the Invention
There is therefore a need for a traction chain that can be installed on an
endless rubber
track to improve its traction capability.
Other and further objects and advantages of the present invention will be
obvious upon an
understanding of the illustrative embodiments about to be described or will be
indicated
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in the appended claims, and various advantages not referred to herein will
occur to one
skilled in the art upon employment of the invention in practice.
Summary of the Invention
To attain these and other objects which will become more apparent as the
description
proceeds according to one aspect of the present invention, there is provided a
traction
chain assembly for an endless traction band.
The traction chain assembly of the present invention is designed to be
installed on the
outer ground-engaging surface of an endless rubber traction band having an
outer surface
and an inner surface. The traction chain assembly is used to improved the
traction of a
tracked vehicle when the driving conditions are such that the friction between
the track
and the ground is too low.
The traction chain assembly preferably comprises at least two laterally
extending parallel
chains, cables or the like. These chains are removably attached on both sides
of the track
using attaching brackets and screws, bolts and nuts or the like.
The two chains are also linked together via different types of traction
enhancing chain
devices.
A first type of traction enhancing chain device is a traction enhancing chain,
extending
between both parallel chains. The particularity of these chains is that their
links
comprises outwardly projecting grousers. These grousers help improve the
traction of the
endless track.
A second type of traction enhancing chain comprises a large, preferably
central, traction
ring, preferably in the form of a circle. Other shapes could also be used. The
traction
ring also comprises a plurality of outwardly projecting grousers. 'The
traction ring
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preferably sits on the top of a ground engaging lug of the outer surface of
the traction
band. The traction ring is connected to both parallel chains via at least two,
but
preferably four, chain segments. The links of these chain segments may also
comprise
grousers.
Preferably, a plurality of these traction chain assemblies are installed on
the traction band
to improve its traction capability.
Other aspects and many of the attendant advantages will be more readily
appreciated as
the same becomes better understood by reference to the following detailed
description
and considered in connection with the accompanying drawings in which like
reference
symbols designate like elements throughout the figures.
Descriution of the Drawings
For a fuller understanding of the nature and object of the invention,
reference should be
had to the following detailed description taken in connection with the
accompanying
drawings in which:
Figure 1 is an isometric view of the traction chain assembly as installed on
an endless
track.
Figure 2 is a side view of the traction chain assembly as installed on an
endless track.
Figure 3 is an close-up isometric view of the traction ring of the traction
chain assembly.
Description of a Preferred Embodiment
'30
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Refernng to Figs. 1-3, the traction chain assembly 20 of the present invention
is to be
installed on an endless traction band 10. The traction band 10 comprises an
inner surface
11 and an outer surface 12. The inner surface 11 comprises a plurality of
guide lugs 13 to
drivingly engage a sprocket wheel (not shown). The outer surface 12 comprises
a
plurality of ground-engaging traction lugs 14 made of rubber. The pattern of
the ground-
engaging lugs 14 may be chosen to fit any particular terrain or use of the
tracked vehicle.
The traction chain assembly 20 comprises two, parallel and laterally extending
chains 21.
Each chain 21 is composed of a plurality of chain links 22. These chain links
22 are
ordinary links known in the art. Chains 21 are removably attached to the
traction band 10
via attachment brackets 23 and screws 24. The brackets 23 are screwed or
otherwise
attached to the side of guide lugs 13 as to not hinder to good functioning of
the traction
band 10. The brackets 23 comprise a pair of hooks 25 to attach the chains 21
to the
brackets 23.
The two parallel chains 21 are linked together by traction enhancing chain
devices 30 and
40.
Traction enhancing chain device 30 is made of a chain segment 31. The chain
segment
31 comprises a plurality of chain links 32. The number of chain links 32 is
chosen
depending on the size of the traction chain assembly 20, the size of the
endless track 10
and the size of each link 32. The number of chain links 32 is a design choice.
Each link
32 is an oval-shaped link which further comprises at least one outwardly
projecting
grouser 33. Grouser 33 improves the traction of the endless track 10.
Traction enhancing chain device 40 is more complex than traction enhancing
chain
device 30. Referring particularly to Figs. 1 and 3, traction enhancing chain
device 40
comprises a central traction ring 41. Traction ring 41 comprises a plurality
of outwardly
projecting grousers 42. Grousers 42 act like grousers 33 and improve the
traction of the
traction band 10. The size and shape of grousers 42 (and 33) are chosen to
best fit the
surface onto which the grousers 42 and 33 will be used. Thus, other sizes and
shapes are
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possible without departing from the scope of the invention. Also, even if in
the preferred
embodiment, the traction ring 41 has the shape of a ring, other shapes like
polygonal and
oval shapes are possible. Traction ring 41 is attached to both chains 21 via
at least two
chain segments 43. Chain segments 43 comprises a plurality of chain links 44.
Even
though they are not shown in Figs. 1-3, chain links 44 can comprise outwardly
projecting
grousers.
As shown in Figs. 1 and 3, traction enhancing chain devices 30 and 40 are
preferably
mounted over ground-engaging lugs 14 as to further improve the traction of the
endless
track 10.
Furthermore, even though the embodiment of Fig. 1 comprises only two traction
enhancing chain devices 30 and two traction enhancing chain devices 40, it is
to be
understood that the embodiment of Fig. 1 is by no means limitative in nature
and that the
number, placement and design of the traction enhancing chain devices 30 and 40
may
vary according to the size and design of the endless track 10 and also
according to the
intended surface of use of the endless track 10. Thus, other designs, shapes
and
configurations are possible without departing from the scope of the invention.
Since traction chain assembly 20 is to sustain repeated impacts, traction
chain assembly
20 is preferably made of high-strength metal such as stainless steel, heat
treated steel,
forged steel or other shock-resistant alloys.
To install the traction chain assembly 20 on the endless track 10, the user
must first align
the first attachment bracket 23 with a first guide lug 13 and then screw the
bracket into
the first guide lug 23 with a first screw 24. Then, the user aligns the second
attachment
bracket 23 with a second guide lug 13, located on the opposite side of the
endless track
10 and then screws the second bracket 23 in the second lug with a second screw
24. The
traction chain assembly 20 must preferably be fully assembled prior to being
installed on
an endless track 10.
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Upon installation, the traction chain 20 should be tightly pressed against
endless track 10
outer surface I 2.
In another preferred embodiment of the present invention, the laterally
extending chains
21 are replaced by laterally extending cables. The chain segments 43 can also
be
replaced by cables.
In another embodiment, the guide lug 13 onto which the bracket 23 is installed
further
comprises a laterally extending hole, going through the entire width of the
lug 13. In this
embodiment, the bracket 23 is fixedly attached to the guide lug 13 with a bolt
and nut
assembly. The bolt is inserted in the laterally extending hole. The nut is
then screwed
onto the bolt to fixedly attach bracket 23. In a variant of this embodiment,
the nut is
directly embedded into the guide lug during the manufacture of the endless
track 10.
In yet another embodiment, the brackets 23 of the traction chain assembly 20
are fixedly
attached in the outer ground engaging lugs 14 of the endless track 10 using
screws.
Although the present traction chain for an endless track has been described
with a certain
degree of particularity, it is to be understood that the disclosure has been
made by way of
example only and that the present invention is not limited to the features of
the
embodiments) described and illustrated herein, but includes all variations and
modifications within the scope and spirit of the invention as hereinafter
claimed.
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