Note: Descriptions are shown in the official language in which they were submitted.
CA 02508741 2005-08-09
WHEEL ASSEMBLY FOR A TRACKED VEHICLE AND ANTI-
ACCUMULATION SLEEVE THEREFOR
FIELD
The present disclosure relates to all-terrain tracked vehicles, and more
particularly, to an improved wheel assembly for such tracked vehicles.
BACKGROUND
Endless track-driven vehicles are commonly used off-road in difficult
terrain and under difficult terrain conditions, such as in mud, snow, sand,
and
tundra. For example, tracked vehicles are used in snow country for grooming
ski slopes and snow mobile trails, for transporting skiers to back-country
slopes,
for ski resort maintenance work, and for snow and mountain rescue. They are
also used in various types of terrain for utility company maintenance work,
and
for oil exploration and oil pipeline maintenance in arctic tundra.
Tracked vehicles are generally of two types. Many are two-tracked in
which a pair of endless drive track units, one on each of the opposite sides
of
the vehicle, support and drive the vehicle. Others are four-tracked, in which
four separately driven and independently suspended drive track units, two in
front and two in the rear, support and drive the vehicle.
Four-tracked vehicles have certain advantages over two-tracked vehicles
under extreme conditions such as on steep slopes and in very rough terrain
because of the flexible independent suspensions of the track drive units and
the
constant power available to all of the track drive units, even while turning.
Unlike a two-tracked vehicle which relies on the differential speed of the two
tracks for turning, a four-tracked vehicle steers much like a wheeled vehicle.
Its
endless drive track units can be physically turned for steering.
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In many tracked vehicles, such as the four tracked vehicles shown in
U.S. Patent No. 6,007,166, the lower, ground-engaging run of the track has
been supported by a plurality of single-element guide wheels disposed
substantially inline longitudinally of the track and generally engaging only a
centralized region of the track. Although this system, with a single line or
row of
guide wheels, functioned adequately, it was found that substantial deflection
of
the track on opposite sides of the guide wheels was occurring. This deflection
was caused generally by the high-point loading of the track by the guide
wheels
at the center of the lateral dimensions of the track. This could lead to
premature failure of elements in the track due to high cyclical stresses. This
same high-point loading of the track and its consequential deflection could
also
lead to premature failure of the track and reduce its effective traction. The
high-
point loading of the track can also be transmitted through the track to the
underlying terrain. In the case of sensitive terrain such as tundra, such
loading
] 5 could cause excessive damage to the terrain, especially with an endless
track
that includes traction bars or cleats on its outer surface for enhancing the
vehicle's traction.
The drive track unit disclosed in U.S. Patent No. 6,129,426, addressed
the foregoing problems by providing guide wheel assemblies along the lower
track run, with each assembly includirig multiple guide wheels mounted on a
common guide wheel hub. This increased the guide wheel surface contact area
across the width of the track, thereby reducing point loading of the track and
consequential track deflection and wear, as well as terrain damage. Although
this was a substantial improvement over the prior art, a problem with such
guide
wheel assemblies is that snow and/or ice can adhere to the outer surface of
the
hub between the guide wheels. Once a snow/ice layer is formed over the hub,
additional snow and/or ice can quickly accumulate between the wheels, which
can cause the track to "derail" or disengage from the guide wheels.
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SUMMARY
The present disclosure concerns embodiments of an improved wheel
assembly for a drive track unit of an all-terrain vehicle that inhibits the
accumulation of snow, ice and/or other matter between the track and the wheel
assembly. The wheel assembly includes a sleeve extending around the
rotatable hub of the wheel assembly and having a deformable and/or flexible
outer surface portion that is capable of deforming under external pressure
applied to the sleeve through contact with snow, ice, or other matter as the
vehicle traverses the ground. The deformation of the sleeve is effective to
inhibit snow, ice, or other matter from adhering to the sleeve outer surface
between the wheels of the wheel assembly. As a result, disengagement of the
track from the wheel assembly caused by accumulated ice, snow, and/or other
matter can be avoided.
The deformable outer surface portion of the sleeve preferably is an
uneven surface portion, for example, a plurality of projections and/or pockets
formed on the sleeve. In certain embodiments, the sleeve comprises a plurality
of deformable, circumferentially spaced projections formed on the outer
surface
of the sleeve. The projections desirably are elongated axially of the sleeve
and
are equally spaced around the circumference of the sleeve so as to define a
plurality of axially extending pockets, or channels, between adjacent
projections. The resulting pressure angles on the projections and flexure of
the
projections assists in releasing snow and/or ice that comes in contact with
the
sleeve outer surface.
The portion of the hub outer surface covered by the sleeve can be
formed with one or more recesses. The sleeve therefore can flex radially
inwardly into the recesses of the hub under external pressure applied to the
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sleeve. The additional flexure of the sleeve further inhibits the adherence of
snow and/or ice on the outer surface of the sleeve.
In one implementation, the wheel assembly comprises a guide wheel
assembly for a track unit and the sleeve is mounted on the hub between the
guide wheels of the guide wheel assembly. In another implementation, the
wheel assembly comprises a drive wheel assembly for a track unit and the
sleeve is mounted on the hub between the drive sprocket wheels of the drive
wheel assembly.
In one representative embodirr,ent, a wheel assembly for an endless
drive track of a drive track unit of an all-terrain vehicle comprises a
rotatable
hub having an outer surface and at least first and second wheels mounted to
opposite sides of the hub for engaging the track. A sleeve extends around the
outer surface of the hub and has an outer surface spaced from the track. The
outer surface of the sleeve defines a plurality of circumferentially spaced-
apart,
deformable projections. External pressure on the sleeve during use causes the
sleeve to deform, thereby inhibiting the accumulation of snow or ice on the
outer surface of the sleeve.
In another representative embodiment, a guide wheel assembly for an
endless drive track of a drive track unit of an all-terrain vehicle comprises
a
rotatable hub having an outer surface and at least first and second axially
spaced apart guide wheels coupled to the hub for engaging the track. An
elastomeric sleeve extends around the outer surface of the hub and has an
outer surface spaced from the track. The sleeve outer surface defines a
plurality of circumferentially spaced pockets elongated in a direction
extending
between opposite end portions of the sleeve. Flexure of the sleeve through
contact with snow or ice is effective to irihibit the accumulation of snow or
ice on
the outer suiface of the sleeve.
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In another representative embodiment, a wheel assembly for an endless
drive track of a drive track unit of an all-terrain vehicle comprises a
rotatable
hub having an outer surface and at least first and second wheels coupled to
opposite sides of the hub for engaging the track. A sleeve extends around the
outer surface of the hub and has an outer surface spaced from the track. The
outer surface comprises a deformable surface portion, wherein external
pressure on the sleeve during use causes the deformable surface portion to
deform, thereby inhibiting the accumulation of snow or ice on the outer
surface
of the sleeve.
In another representative embodiment, a sleeve is provided for use in a
wheel assembly of a drive track unit of an all-terrain vehicle in which the
wheel
assembly has at least two spaced apart wheels. The sleeve comprises a
deformable outer surface portion, wherein deformation of the outer surface
portion through contact with snow or ice is effective to inhibit the
accumulation
of snow or ice on the sleeve.
In another representative embodiment, a sleeve for use in a wheel
assembly of a drive track unit of an all-terrain vehicle comprises a plurality
of
deformable projections, wherein deformation of the projections through contact
with snow or ice is effective to inhibit the accumulation of snow or ice on
the
sleeve.
In another representative embodiment, a track unit for a track-driven all-
terrain vehicle comprises a track frame, a drive wheel assembly that is
rotatably
mounted to the frame, and plural guide wheel assemblies that are rotatably
mounted to the frame. An endless track is trained about the drive wheel
assembly and the guide wheel assemblies and is drivingly engaged by the drive
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wheel assembly. At least one of the guide wheel assemblies comprises a
rotatable hub, at least first and second guide wheels coupled to the hub and
engaging the track, and an elastomeric sleeve covering the hub. The sleeve
has an outer surface formed with a plurality of circumferentially spaced,
axially
extending pockets. Deformation of the sleeve through contact with snow or ice
is effective to inhibit the adherence of snow or ice on the outer surface of
the
sleeve.
The foregoing and other objects, features, and advantages of the
invention will become more apparent from the following detailed description,
which proceeds with reference to the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a four-tracked all terrain vehicle having
endless track units supported on guide wheel assemblies, according to one
embodiment.
FIG. 2 is an enlarged side elevation view of an endless track unit of the
vehicle showr- in FIG. 1.
FIG. 3 is an enlarged, fragmentary cross sectional view of the track and
drive wheel assembly of FIG. 2 taken generally along line 3-3 in FIG. 2.
FIG. 4 is an enlarged perspective view of one of the guide wheel
assemblies of the track unit shown in FIG. 2.
FIG. 5 is an enlarged side elevation view of the guide wheel assembly
shown in FIG. 4.
FIG. 6 is an enlarged cross sectional view of the guide wheel assembly
taken generally along line 6-6 of FIG. 5.
FIG. 7 is an enlarged perspective view of the flexible sleeve of FIG. 4
shown removed from the guide wheel assembly for clarity.
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FIG. 8 is an enlarged side elevation view of the flexible sleeve shown in
FIG. 7.
FIG. 9 is an enlarged cross sectional view of the flexible sleeve taken
generally along line 9-9 of FIG. 8.
FIG. 10 is an enlarged side elevation view of a flexible sleeve that can be
used in the guide wheel assembly shown in FIG. 4, according to another
embodiment.
FIGS. 11A and 116 are enlarged side elevation and perspective views,
respectively, of a flexible sleeve that can be used in the guide wheel
assembly
shown in FIG. 4, according to another embodiment.
FIG. 12 is an enlarged side elevation view of a flexible sleeve that can be
used in the guide wheel assembly shown in FIG. 4, according to another
embodiment.
FIG. 13 is an enlarged side elevation view of a flexible sleeve that can be
used in the guide wheel assembly shown in FIG. 4, according to another
embodiment.
FIGS. 14A-14G show various embodiments of sleeves having
deformable projections that can be used in the guide wheel assembly shown in
FIG. 4.
DETAILED DESCRIPTION
As used herein, the singular forms "a," "an," and "the" refer to one or
more than one, unless the context clearly dictates otherwise.
As used herein, the term "includes" means "comprises."
The present disclosure concerris embodiments of an improved wheel
assembly for a track unit of an all-terrain vehicle, such as disclosed in U.S.
Patent Nos. 6,129,426, 6,007,166, 3,787,099, and 3,857,616, that inhibits the
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accumulation of snow and/or ice between the track and the wheel assembly.
Referring first to FIG. 1, a four-tracked all-terrain vehicle 10 is shown
having a vehicle body 12 supported by four identical endless track units 14,
16,
18, and 20, respectively. The track assemblies 14 and 20 are mounted at
opposite sides of the rear of the vehicle, while the track assemblies 16, 18
are
mounted at opposite sides of the front of the vehicle. Each endless track
assembly is independently mounted, driven and steerable in a well-known
manner. At the forward end of the vehicle a snow plow, or grader blade, 22 is
illustrated. It should be recognized that a vehicle as shown is adapted to
have
a variety of attachments mounted at its front or rear ends for multiple
operations
over a variety of terrain, as well as a variety of body types for various
purposes.
Referring to FIGS. 2 and 3, one of the track units 16 is illustrated in
greater detail. The track unit 16 is mounted to the vehicle body through a
frame
structure 26. The frame structure 26 includes an elongate and substantially
horizontal beam 28 extending longitudinally of the track unit 16 and a set of
diverging outer legs 30a and 30b and a set of diverging inner legs 32a, 32b.
The upper ends of legs 30a, 30b, 32a, 32b are secured to a journal tube 36
(FIG. 3) which is mounted to the chassis of the vehicle body 12. The divergent
lower ends of the inner and outer legs are secured to beam 28.
The track unit 16 has a drive wheel assembly 38 at the apex of a
generally triangularly-shaped path for an endless track 58. The drive wheel
assembly 38 is rotatably driven by a powered axle 40 extending through journal
tube 36. The drive wheel assembly 38 includes a drum, or hub, 42 with
sprocket discs 44a, 44b (also referred to herein as sprocket wheels) mounted
at
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opposite ends of the drum (FIG. 3). Opposed sprocket discs 44a, 44b are
axially spaced apart to form a gap 46 therebetween.
Each sprocket disc 44a, 44b has a plurality of track engaging members
in the form of cogs 50 equally-spaced about the circumference of the disc,
with
each cog 50 rigidly secured thereto and extending perpendicularly outwardly
therefrom. Each cog 50 forms a tooth for the sprocket disc.
As shown in FIG. 2, five lower, freely rotatable guide wheel assemblies
54 are spaced in a line extending longitudinally of the track assembly and
alongside beam 28. The guide wheel assemblies 54 can be equally spaced
along the beam 28, or alternatively, the spacing between the guide wheel
assemblies can vary, depending on the particular track unit configuration. The
rearmost wheel assembly 54 is mounted on a telescoping wheel support 56.
The telescoping wheel support includes a threaded adjustment assembly which
when rotated either extends or retracts the rearmost guide wheel assembly 54
longitudinally of the track assembly. While the illustrated track unit 16 has
five
guide wheel assemblies, a greater or fewer number of guide wheel assemblies
can be used.
The endless track 58 is trained about the outside of drive wheel
assembly 38 and guide wheel assemblies 54 to form a generally triangularly-
shaped track run. In alternative embodiments, the track unit can a drive wheel
assembly that is positioned substantially in-line with the guide wheel
assemblies, for example in front of the forwardmost guide wheel assembly or in
back of the rearmost guide wheel assembly.
As best shown in FIG. 2, the track 58 in the illustrated configuration
generally is a one piece, endless molded rubber belt with internally cast
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composite stiffener rods (not shown) preferably of fiberglass composite,
rubber,
and/or aluminum, and positioned, for example, every 4.166 inches, extending
perpendicular to the track run. Internally cast flexible, stretched-resistant
cords
(not shown) preferably constructed of a combination of kevlar, nylon, and
steel
cable extend parallel to the track run. One known manufacturer of endless
tracks containing such materials is Carrioplast, Inc., located in Plattsburgh,
N.Y.
Molded drive lugs 60a, 60b, 60c, 60d molded in place and preferably
constructed of hard rubber are positioned on the inside of track 58 to engage
and mesh with cogs 50 for driving the track 58. As is seen the illustrated
drive
lugs are generally truncated pyramid-shaped, although they can have other
suitable shapes. The drive cogs 50 are positioned and shaped to enter the
spaces between longitudinally aligned drive lugs 60a, 60b, 60c, 60d to drive
the
track.
As shown in FIGS. 2 and 3, the molded track, or tread, has traction bars
62, preferably of rubber, extending laterally across the outside of the track
58.
These are substantially equally spaced around the track periphery.
Transversely extending grooves 64 in the tread further improve traction for
the
vehicle.
A pair of scrapers 66a, 66b (FIG. 3) constructed of hard rubber, molded
in place as part of the track and having a generally triangular cross-section,
are
positioned on the inside of the track. The scrapers are positioned to travel
along the path of the track and to aid in clearing debris, such as snow, ice,
sand, etc., should it build up in the area about journal assembly 36.
FIGS. 4-6 show one of the guide wheel assemblies 54 in greater detail.
The illustrate:.i guide wheel assembly 54 includes a spindle, or axle, 70
having
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an end portion 72 that extends through a corresponding opening in beam 28
(FIG. 2). The spindle 70 is secured to beam 28, such as by a removable pin 74
that extends through the end portion 72. A hub 76 is rotatably mounted on the
opposite end portion 78 of the spindle 70 through bearings 80 and is locked
thereon by a nut 82 (as best shown in FIG. 6).
First and second, axially spaced apart guide wheels 84a and 84b are
mounted on opposite sides of the hub 76 by bolts 86 and nuts 88. The wheels
84a, 84b can have elastomeric outer coverings 90a and 90b, respectively, that
contact the inner surface of the track 58. The outer coverings 90a, 90b can be
made of rubber or polyester material to provide cushioning between the track
58 and the guide wheel assembly 54.
Exteriding axially between the guide wheels 84a, 84b and around the
outer surface of the hub 76 is a defonrnable sleeve, or outer covering, 92
that
functions to inhibit the accumulation of ice, snow, mud or other matter on the
outer surface of the hub. The sleeve 92 preferably is made of an elastomeric
material, such as rubber or urethane, that can deform or flex under external
pressure applied to the sleeve through contact with snow and/or ice (or other
matter) as the vehicle traverses the ground. As shown, the sleeve 92 desirably
covers the entire outer surface of the hub 76 between the guide wheels 84a,
84b to prevent ice and/or snow from contacting the outer surface of the hub.
In
other embodiments, the sleeve 92 can be sized to cover less than the entire
outer surface of the hub. For example, the sleeve 92 can be sized to cover
only
a center portion of the hub outer surface.
Referring also to FIGS. 7-9, the sleeve 92 has an outer surface 93
formed with a plurality of circumferentially spaced and axially extending
raised
rib portions, or projections, 96 that are equally spaced around the hub. A
plurality of axially extending pockets, or cavities, 94 are defined between
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adjacent projections 96. The projections 96 and the pockets 94 desirably
extend at least the majority of the length of the sleeve 92 (as measured in
the
axial direction, or along the longitudinal axis, of the sleeve) (i.e., the
projections
and the pockets extend at least half the length of the sleeve) and can extend
substantially the entire length of the sleeve 92 as shown. In other
embodiments, the pockets can extend less than the majority of the length of
the
sleeve.
The sleeve 92 can include end walls 98, 100 at opposite ends of the
sleeve forming respective end walis of the pockets 94. As best shown in FIG.
9, each projection 96 has sloped side surfaces 102 and 104 extending axially
between end portions 98, 100 and converging toward each other in a radial
outward direction. Each pocket 94 has a curved bottom surface 106 extending
between surfaces 102, 104 of an adjacent pair of projections 96. In other
embodiments, the projections and/or pockets can have other cross-sectional
profiles. For example, projections can have a generally square or rectangular
cross-sectional profile with non-sloped side surfaces and the pockets can have
flat bottom surfaces.
As shown in FIG. 9, each pocket 94 is defined by surfaces 102, 104 of
adjacent projections that define an angle a. The surfaces 102, 104 of each
projection define an angle w. In particular embodiments, the angle a is about
90 degrees and the angle w is about 20 to 75 degrees, with 71 degrees being a
specific example. However, these angles can be varied as needed in different
situations or applications.
In certain embodiments, the sleeve 92 is molded from a suitable
elastomeric material and has a one-piece, monolithic construction as shown.
As used herein, the term "monolithic construction" refers to a construction
that
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does not include any welds, fasteners, adhesives, or other means for securing
separately formed pieces of material to each other. In alternative
embodiments,
however, the sleeve can comprise multiple pieces secured to each other and/or
to the hub outer surface. In one implementation, for example, the sleeve 92
can have a base layer, which can be made of an elastomeric or non-
elastomeric material, and a plurality of deformable projections made of an
elastomeric material and secured to the base layer.
As the vehicle traverses the ground, pressure is applied to the outer
surface of the sleeve 92 through contact with snow and/or ice (or other
matter),
causing the projections 96 to flex. The sloped side surfaces 102, 104 of the
projections 96 provide a varying contact surface (that is, the sleeve outer
surface contacting the snow and/or ice does not have a constant outer
diameter) that effectively varies the resulting pressure angles on the sleeve
outer surface as the sleeve rotates over the ground. The flexure of the
projections 96 and the resulting pressure angles against the sleeve outer
surface inhibits the adherence and subsequent built up of snow and/or ice (or
other matter) on the outer surface of the sleeve 92. The curved bottom
surfaces 106 between the projections 96 also facilitates the release of snow
and/or ice from the sleeve. Hence, disengagement of the track 58 from the
guide wheels 90a, 90b caused by accumulated snow and ice can be avoided.
As shown in FIG. 6, the outer surface of the hub 76 can be formed with
one or more continuous annular recesses 108, 110 extending around the hub.
A continuous annular flange 112 located generally at the middle of the hub
separates the recesses 108, 110 and supports the sleeve 92 between the
recesses. The recesses 108, 110 allow the sleeve 92 to flex radially inwardly
under external pressure applied to the sleeve. The additional flexure of the
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sleeve 92 further assists in releasing snow and/or ice that comes in contact
with
the outer surface 93 of the sleeve 92.
As shown in FIG. 3, a deformable sleeve 120 having a construction
similar to that of the sleeve 92 can be used to cover the outer surface of the
drive wheel hub 42 between the sprocket discs 44a, 44b to inhibit the
accumulation of snow and/or ice on the drive wheel assembly 38. The hub 42
can be formed with one or more annular recesses (not shown) to allow the
sleeve 120 to flex radially inwardly under external pressure applied to the
sleeve.
The sleeves 92, 120 (or any of the other sleeves disclosed herein) are
not restricted in use to the specific guide wheel assembly, drive wheel
assembly, track, or track unit shown in the illustrated embodiment.
Accordingly,
the sleeves 92, 120 (or any of the other sleeves disclosed herein) can be
implemented in various types of wheel assembly, track, or track unit
configuratioris.
For example, the sleeve 92 can be implemented in a guide wheel
assembly haaing three or more spaced-apart guide wheels or in a drive wheel
assembly having three or more spaced-apart sprocket drive wheels. In one
embodiment, for example, a guide wheel assembly comprises a hub and three
guide wheels mounted to the hub in an axially spaced relationship, such as
disclosed in U.S. Patent No. 6,129,426. Multiple sleeves 92 cover the outer
surface of ttie hub between adjacent guide wheels.
FIG. 10 shows a deformable sleeve 92', according to another
embodiment, that can be used in the guide wheel assembly 54 and/or the drive
wheel assembly 38. The sleeve 92' is similar in construction to the sleeve 92
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except that the sleeve 92' is formed with a circumferentially extending rib
portion 150 so as to define rows of axially spaced-apart pockets 94. The
sleeve
92' can be formed with additional circumferentially extending rib portions 150
so
as to form rows of three or more axially spaced-apart pockets. In an
alternative
embodiment, the sleeve 92' can be formed with one or more circumferentially
extending grooves (not shown) where the rib portions 150 are located so as to
form rows of axially spaced-apart, discrete projections.
FIGS. 11A and 11B show a deformable sleeve 200, according to another
embodiment, that can be used in the guide wheel assembly 54 and/or the drive
wheel assembly 38. The sleeve 200 includes a plurality of axially spaced-apart
ribs or projections 202 that extend continuously around the circumference of
the
sleeve. A plurality of annular grooves, or pockets, 204 are defined between
adjacent projections 202.
FIG. 12 shows a deformable sleeve 250, according to another
embodiment, that can be used in the guide wheel assembly 54 and/or the drive
wheel assembly 38. The sleeve 250 is formed with a series of non-continuous,
circumferentially extending, axially spaced-apart ribs, or projections, 252,
alternating with circumferentially extending, axially spaced-apart grooves, or
pockets, 254. A series of axially extending, circumferentially space-apart rib
portions 256 separate the grooves 254 into discrete rows of grooves 254
extending axially of the sleeve 250. In an alternative embodiment, a series of
grooves (not shown) can be formed where the rib portions 256 are located so
as to separate the projections 252 into discrete axially extending rows of
projections 252, with the rows being circumferentially spaced-apart from each
other.
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FIG. 13 shows a deformable sleeve 300, according to another
embodiment, that can be used in the guide wheel assembly 54 and/or the drive
wheel assembly 38. The sleeve 300 has an outer surface 302 and a plurality of
recesses, or pockets, 304 formed in the outer surface. The pockets 304 in the
illustrated configuration are generally circular in shape. However, the
pockets
304 can have various other shapes, such as a square, rectangle, triangle,
diamond, or various combinations thereof. The pockets 304 can be arranged in
rows of pockets, for example axially extending rows of three pockets each
alternating with axially extending rows of two pockets each as shown.
Alternatively, the sleeve 300 can have an irregular pattern of pockets 304
randomly positioned in the outer surface 302.
FIG. 14A shows a deformable sleeve 350, according to another
embodiment, that can be used in the guide wheel assembly 54 and/or the drive
wheel assembly 38. The sleeve 350 has an outer surface 352 and a plurality of
projections 354 extending outwardly from the outer surface 352. Each of the
projections 354 in the illustrated configuration has an enlarged base that
tapers
into a cylindrically shaped upper portion. However, the projections 354 can
have various other shapes, such as a square, rectangle, triangle, cone,
pyramid, diamond, or various combinations thereof. The projections 354 can be
arranged in rows of projections, for example axially extending rows of three
projections each alternating with axially extending rows of two projections
each
as shown. Alternatively, the sleeve 350 can have an irregular pattern of
projections 354 randomly positioned on the outer surface 352. The sleeve 350
can be made entirely of an elastomeric material (e.g., urethane or rubber)
using
suitable techniques. Alternatively, the sleeve 350 can have a non-deformable
and non-elastomeric base layer and deformable projections made of an
elastomeric rnaterial and secured to the base layer. In another embodiment, a
sleeve can have a plurality of projections 354 (FIG. 14) and pockets 304 (FIG.
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13), arranged in organized rows or randomly positioned on the outer surface of
the sleeve.
FIGS. 14B-14G show various other embodiments of sleeves having
deformable projections for use in the guide wheel assembly 54 and/or the drive
wheel assembly 38. FIG. 14B shows a sleeve having projections 360 that are
generally frusto-pyramidal in shape. The projections 360 are aligned in
axially
and circumferentially extending rows with the base of each projection
contacting
the base of an adjacent projection on all four of its sides (except for the
projections at the end of each axially extending row, which contact adjacent
projections on only three sides thereof)
FIG. 14C shows a sleeve having generally frusto-pyramidal projections
370 elongated in the circumferential direction. The projections 370 are
aligned
in axially extending rows with the base of each projection 370 contacting the
bases of adjacent projections in the same row (except for the projections 370
at
the ends of each axially extending row, which contact an adjacent projection
on
only one side thereof). The projections 370 are also aligned in
circumferentially
extending rows with curved surfaces extending between the bases of adjacent
projections in the same circumferentially extending row.
FIG. 14D shows a sleeve having generally frusto-pyramidal projections
380 and having a construction similar to the sleeve shown in FIG. 14B, except
that the projections 380 are elongated in the circumferential direction. Also,
the
rows of projections extending between the ends of the sleeve are skewed
slightly with respect to the longitudinal axis of the sleeve.
FIG. 14E shows a sleeve having generally frusto-pyramidal projections
390 that are elongated in the axial direction. The projections 390 are aligned
in
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axially extending rows with the base of each projection 390 contacting the
bases of adjacent projections in the same row (except for the projections 390
at
the ends of each axially extending row, which contact an adjacent projection
on
only one side thereof). The projections 390 are also staggered or offset from
projections in adjacent rows.
FIG. 14F show a sleeve having generally frusto-pyramidal projections
400 elongated in the axial direction and aligned in axially extending rows.
The
bases of the projections 400 in each axially extending row contact the bases
of
adjacent projections in the same row (except for the projections 400 at the
ends
of each axially extending row, which contact an adjacent projection on only
one
side thereof). The projections 400 are also aligned in circumferentially
extending rows with curved surfaces extending between the bases of adjacent
projections in the same circumferentially extending row.
FIG. 14G shows a sleeve having generally frusto-pyramidal projections
410. The sleeve of FIG. 14G is similar to the sleeve shown in FIG. 14D except
that the projections 410 are longer in the circumferential direction than the
projections 380 shown in FIG. 14D.
In view of the many possible embodiments to which the principles of the
disclosed invention may be applied, it should be recognized that the
illustrated
embodiments are only preferred examples of the invention and should not be
taken as limiting the scope of the invention. Rather, the scope of the
invention
is defined by the following claims. I therefore claim as my invention all that
comes within the scope and spirit of these claims.
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