Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED ENDLESS TRACK BELT
Field of the Invention
This invention relates to endless rubber track belts.
Background of the Invention
Rubber endless tracks such as for use on agricultural or industrial vehicles
typically have
an internal center ribbon of individual lugs which engage drive bars on a
drive wheel. The
continued use and contact between the drive bar and drive lugs cause internal
lug stresses, and
surface wear at the points of contact. Additionally, the internal center
ribbon of lugs are typically
functioning not only to transmit power from the drive wheel to the track, but
also to retain the
track onto the vehicle. Contact between the vehicle undercarriage wheels and
the longitudinal or
guide surfaces of the inner lugs frequently occurs as the vehicle maneuvers
during normal
service. This contact can cause wearing of the inner lugs which can be severe
depending upon
various vehicle design features and usage applications. Driving and/or guiding
forces on the
inner lugs, henceforth referred to as guide-drive lugs, can lead to eventual
chunking of the rubber
surface and possibly to complete removal of the drive lugs, making the track
unserviceable. Thus
a track belt having guide-drive lugs which are stronger and more resistant to
wear is desired.
Summary of the Invention
The invention provides in a first aspect an endless rubber track belt
coniprising a rubber
carcass having an inner surface having one or more guide-drive lugs and an
outer surface having
tread lugs, the guide-drive lugs having a reinforcement layer which extends
substantially along
the width of the drive lug.
Brief Description of the Drawings
Figure 1 is a perspective view of an endless rubber track assembly.
Figure 2 is a perspective view of a section of the endless rubber track shown
in Figure 1;
Figure 3 is a perspective view of a drive lug.
Figure 4 is a cross-sectional view of the endless rubber track of Figure 2 in
the direction
4-4; Figure 5 is a cross-sectional view of the endless rubber track of Figure
2 in the direction
5-5;
Detailed Description of the Invention
Figure 1 illustrates a track assembly 10 which may be used on an industrial or
agricultural
vehicle (not shown). The track assembly 10 includes a drive wheel 12
comprising a plurality of
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teeth or drive bars 14 which are positioned for mating engagement with guide-
drive lugs 16. The
drive lugs 16 are mounted on a rubber track 20 having an endless elongate
carcass. The endless
track carcass has an outer surface 22 comprising a plurality of ground
engaging tread lugs 24 and
an inner surface 26 with a plurality of guide-drive lugs 16, typically located
on the center portion
of the carcass.
The guide-drive lugs 16 as shown in Figure 3 comprise an elongate shaped bar
with
inclined drive faces 17, 19 and an upper flat face 21. The corners of the
joined faces are rounded
to reduce stress concentrations. Guide faces 23, 25 are also flat. The guide-
drive lugs may also
have various other shapes.
As shown in Figure 2, the belt carcass 20 typically comprises one or more
layers of gum
rubber or elastomeric material 30. Embedded within the gum rubber are one or
more
reinforcement layers 32 which extend transversely along the track width. The
reinforcement
layers may comprise longitudinal cable reinforcement layers, fabric
reinforcement layers or any
other reinforcement layer known to those slcilled in the art.
The guide-drive lugs as shown in Figures 2-4, are comprised of rubber or
elastomeric
material, and have one or more layers of reinforcement material 40 therein.
The reinforcement
material 40 as shown in Figure 3, may completely cover the drive lug and
extend down the sides
of the lug onto the carcass. The reinforcement layer may also optionally
extend continuously all
the way around the track, wherein the width may be slightly greater than the
drive lug width or
be equal to the carcass width, thus providing a protective effect to the drive
lugs and the track
inner surface.
The reinforcement layer, or layers, may comprise the following materials:
nylon, polyester,
polyethylene, polyurethane, rayon, Kevlar, araniid, metal, natural fibers such
as cotton, glass
fibers, carbon fibers, ceramic fibers or plastic fibers. The reinforcement
material may also be a
fiber loaded rubber layer, with fibers oriented in a transverse direction or
in a random direction.
For example, the reinforcement material may comprise tire ply (rubber coated
cords), with the
fibers oriented in any desired orientation. The fibers may be natural fibers
such as cotton, nylon,
polyester, polyethylene, polyurethane, rayon, glass fibers, steel, or plastic.
The invention is not
limited to the reinforcement materials stated above, and may also comprise any
low friction
niaterial considered suitably effective for the specific type of track belt
usage. It is preferable that
the reinforcement material having a low coefficient of friction in the range
of about .10 to about
.80.
If the reinforcement material is tire ply, then two or more layers may be
used. If two or
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more layers are used, the layers may have cords oriented at opposite angular
orientation, e.g.,
layer one has parallel cords oriented at 45 degrees, while layer two has
parallel cords oriented at
- 45 degrees (although any desired angular orientation may be used).
Preferably, light nylon tire
cord is used, which is used in airsprings.
The reinforcement material may comprise the track inner surface or be embedded
under
the track inner surface at a distance d, d typically being in the range of
about .020" to about .13".
Preferably, the reinforcement layer is covered on both sides with a skim coat
layer of rubber.
The reinforcement layer is preferably incorporated into the track belt during
the track belt
manufacturing process. In this case, the reinforcement material is prepared
independently, and
prior to, the track manufacturing process. The track belt can be formed and
vulcanized in a
pressurized molding process. Molds used in said process have shaped lug
cavities which form
guide-drive lugs into their intended final shape. The guide-drive lugs can be
presented to the final
molding process as non premolded extruded pieces, which are cut to length,
approximately the
shape of the lug cross sectional contour. At the ends they may be cut on a
bias to more
approximate the ends of the mold cavities. Otherwise, the lugs may be pre-
molded similar to
what is illustrated in U. S. Patent No. 5,536,464. Said slugs can be covered
individually with
separate pieces of reinforcing materials prior to lugs being presented to the
track belt build and
vulcanization process. Alternatively, the guide-drive lug reinforcing material
can be applied to
the particular surfaces as a continuous piece. In this method, the prepared
inner lug slugs are
positioned onto the inside surface of the uncured carcass at their intended
final molded relative
locations. Then, prior to molding, the single piece of reinforcement is placed
over the green
inner lug slugs. Additional fitting of the reinforcement to the green inner
slugs may be done at
this time; however, the process of compressing the mold may also be relied on
to form fit the
reinforcement over the intended surfaces. After the reinforcement has been
fitted to the inner lug
slugs final vulcanization occurs via imparting appropriate pressure and
temperature onto the
uncured track belt. This is the final step in incorporating the guide-drive
reinforcement to the
track belt.
While certain representative embodiments and details have been shown for the
purpose of
illustrating the invention, it will be apparent to those skilled in this art
that various changes and
modifications may be made therein without departing from the spirit or scope
of the invention.
