U.S. patent application number 14/741538 was filed with the patent office on 2015-10-08 for wheel and tire assembly including a collapsible wheel.
The applicant listed for this patent is Lindsay Corporation. Invention is credited to Thomas J. Korus, Jochen Pfrenger.
Application Number | 20150283856 14/741538 |
Document ID | / |
Family ID | 52466128 |
Filed Date | 2015-10-08 |
United States Patent
Application |
20150283856 |
Kind Code |
A1 |
Pfrenger; Jochen ; et
al. |
October 8, 2015 |
WHEEL AND TIRE ASSEMBLY INCLUDING A COLLAPSIBLE WHEEL
Abstract
A wheel assembly includes a collapsible wheel and an airless
flexible tire mounted on the wheel. The wheel includes a central
portion and a plurality of circumferentially spaced mounting
elements attached to the central portion. Each of the mounting
elements is movable between a retracted position and an extended
position, and may be pivotally attached to the central portion of
the wheel and configured to pivot between the retracted position
and the extended position. The tire may be positioned on the wheel
when one or more of the mounting elements is in the retracted
position, and the one or more mounting elements are moved to the
extended position wherein the mounting elements engage and support
the tire.
Inventors: |
Pfrenger; Jochen; (The
Woodlands, TX) ; Korus; Thomas J.; (Lindsay,
NE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lindsay Corporation |
Omaha |
NE |
US |
|
|
Family ID: |
52466128 |
Appl. No.: |
14/741538 |
Filed: |
June 17, 2015 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
13969197 |
Aug 16, 2013 |
|
|
|
14741538 |
|
|
|
|
Current U.S.
Class: |
157/1.1 |
Current CPC
Class: |
B60C 7/22 20130101; B60B
1/14 20130101; B60C 7/00 20130101; A01G 25/092 20130101; B60B 23/10
20130101; B60B 2900/212 20130101; B60C 7/24 20130101; B60B 23/00
20130101; B60C 11/0311 20130101; B60C 25/01 20130101; B60B 25/02
20130101 |
International
Class: |
B60C 7/24 20060101
B60C007/24; B60C 25/01 20060101 B60C025/01 |
Claims
1. A method of mounting an airless tire on a wheel having a
plurality of mounting elements, the method comprising: moving at
least some of the mounting elements on the wheel from an extended
position to a retracted position; positioning the wheel and the
tire such that the wheel is inside the tire; and moving the at
least some of the mounting elements from the retracted position to
the extended position such that the plurality of mounting elements
engage the tire.
2. The method as set forth in claim 1, the steps of moving at least
some of the plurality of mounting elements from the extended
position to the retracted position and moving at least some of the
mounting elements from the retracted position to the extended
position including moving all of the mounting elements.
3. The method as set forth in claim 1, the steps of moving at least
some of the plurality of mounting elements from the extended
position to the retracted position and moving at least some of the
mounting elements from the retracted position to the extended
position including moving only one of the mounting elements.
4. The method as set forth in claim 1, the steps of moving at least
some of the plurality of mounting elements from the extended
position to the retracted position and moving at least some of the
mounting elements from the retracted position to the extended
position including pivoting the at least some of the mounting
elements.
5. The method as set forth in claim 1, wherein each mounting
element to be moved is connected to the wheel via at least one
fastener, the method further comprising the steps of removing the
at least one fastener from each mounting element to be moved so
that the mounting elements can be moved from the extended position
to the retracted position and connecting the moved mounting
elements to the wheel via the fasteners so as to retain the
mounting elements in the extended position.
6. The method as set forth in claim 5, wherein the at least one
fastener includes first and second fasteners and each mounting
element is configured to be pivoted about the second fastener.
7. The method as set forth in claim 6, wherein the first and second
fasteners are nuts and bolts, and the method further comprises the
step of loosening the first fastener so that the mounting element
can pivot about the second fastener.
8. The method as set forth in claim 1, the step of moving at least
some of the mounting elements on the wheel from the extended
position to the retracted position including pivoting the at least
some of the mounting elements in a first direction and the step of
moving the at least some of the mounting elements on the wheel from
the retracted position to the extended position including pivoting
the at least some of the mounting elements in a second direction
opposite the first direction.
9. The method as set forth in claim 1, the step of moving the at
least some of the mounting elements from the refracted position to
the extended position including urging distal ends of the mounting
elements into drive lugs positioned on an inner side of the
tire.
10. The method as set forth in claim 9, wherein the drive lugs of
the tire each include an annularly extending cross member and the
distal ends of the mounting elements each include a recess
configured to receive the cross member therein for preventing the
tire from shifting laterally relative to the wheel.
11. A method of mounting an airless tire on a wheel of a mobile
tower of an irrigation system, the wheel having a plurality of
mounting elements, the method comprising: moving at least some of
the mounting elements on the wheel from an extended position to a
retracted position; positioning the wheel and the tire such that
the wheel is inside the tire; and moving the at least some of the
mounting elements from the retracted position to the extended
position such that the plurality of mounting elements engage the
tire.
12. The method as set forth in claim 11, the steps of moving at
least some of the plurality of mounting elements from the extended
position to the retracted position and moving at least some of the
mounting elements from the retracted position to the extended
position including moving all of the mounting elements.
13. The method as set forth in claim 11, the steps of moving at
least some of the plurality of mounting elements from the extended
position to the retracted position and moving at least some of the
mounting elements from the retracted position to the extended
position including moving only one of the mounting elements.
14. The method as set forth in claim 11, the steps of moving at
least some of the plurality of mounting elements from the extended
position to the retracted position and moving at least some of the
mounting elements from the retracted position to the extended
position including pivoting the at least some of the mounting
elements.
15. The method as set forth in claim 11, wherein each mounting
element to be moved is connected to the wheel via at least one
fastener, the method further comprising the steps of removing the
at least one fastener from each mounting element to be moved so
that the mounting elements can be moved from the extended position
to the retracted position and connecting the moved mounting
elements to the wheel via the fasteners so as to retain the
mounting elements in the extended position.
16. The method as set forth in claim 15, wherein the at least one
fastener includes first and second fasteners and each mounting
element is configured to be pivoted about the second fastener.
17. The method as set forth in claim 11, the step of moving at
least some of the mounting elements on the wheel from the extended
position to the retracted position including pivoting the at least
some of the mounting elements in a first direction and the step of
moving the at least some of the mounting elements on the wheel from
the retracted position to the extended position including pivoting
the at least some of the mounting elements in a second direction
opposite the first direction.
18. The method as set forth in claim 11, the step of moving the at
least some of the mounting elements from the refracted position to
the extended position including urging distal ends of the mounting
elements into drive lugs positioned on an inner side of the
tire.
19. The method as set forth in claim 18, wherein the drive lugs of
the tire each include an annularly extending cross member and the
distal ends of the mounting elements each include a recess
configured to receive the cross member therein for preventing the
tire from shifting laterally relative to the wheel.
20. A method of mounting an airless tire on a wheel of a mobile
tower of an irrigation system, the wheel having a plurality of
mounting elements, the method comprising: removing a first fastener
connecting each mounting element to the wheel; loosening a second
fastener connecting each mounting element to the wheel; pivoting at
least some of the mounting elements on the wheel about the second
fastener in a first direction from an extended position to a
retracted position; positioning the wheel and the tire such that
the wheel is inside the tire; pivoting the at least some of the
mounting elements about the second fastener in a second direction
from the retracted position to the extended position; inserting
distal ends of the at least some of the mounting elements into
engagement with drive lugs of the tire; inserting annularly
extending cross members of the drive lugs into recesses positioned
on distal ends of the mounting elements for preventing the tire
from shifting laterally relative to the wheel; tightening the
second fastener connecting each mounting element to the wheel;
engaging the first fastener between each mounting element and the
wheel; and tightening the first fastener so that the mounting
elements are coupled to the wheel and firmly engage the tire such
that the tire is secured on the wheel.
Description
RELATED APPLICATIONS
[0001] The present application is a divisional application of
co-pending U.S. Patent Application titled WHEEL AND TIRE ASSEMBLY
INCLUDING A COLLAPSIBLE WHEEL, Ser. No. 13/969,197, filed Aug. 16,
2013. The identified earlier-filed application is hereby
incorporated by reference in its entirety into the present
application.
FIELD
[0002] Embodiments of the present invention relate to wheel and
tire assemblies. More particularly, embodiments of the present
invention relate to wheel and tire assemblies including collapsible
wheels and airless tires presenting certain performance
characteristics of pneumatic tires.
BACKGROUND
[0003] One type of irrigation system includes elevated water
conduits supported by mobile towers. Such mobile towers are mounted
on wheels that propel the towers along the ground to be irrigated.
The wheels typically include pneumatic tires that require periodic
maintenance, including adjusting air pressure, repairing tires that
develop holes or other damage, and replacing old or damaged tires
that are beyond repair.
[0004] Because irrigation systems are typically used in fields or
other remote locations, monitoring the tires for problems and
reaching the tires to perform maintenance and repairs can be
inconvenient or difficult. If a tire loses air pressure and is not
repaired in a timely manner, damage to the tire, to the equipment
mounted on the tire, or both may result.
[0005] One solution to the challenges presented by the use of
pneumatic tires involves using wheels without tires. While this
approach addresses most of the problems of tire maintenance, repair
and replacement, it presents other challenges. Tireless wheels, for
example, are rigid and experience greater ground penetration than a
flexible tire, thereby creating ruts or otherwise disturbing the
land more than a pneumatic tire. Similar problems exist for
tractors, automobiles, and other vehicles that typically use
pneumatic tires.
[0006] The above section provides background information related to
the present disclosure which is not necessarily prior art.
SUMMARY
[0007] A wheel assembly constructed in accordance with an
embodiment of the present invention comprises a wheel and an
airless flexible tire mounted on the wheel. The wheel includes a
central portion and a plurality of circumferentially spaced
mounting elements attached to the central portion. Each of the
mounting elements is movable between a retracted position and an
extended position and support the tire when in the extended
position.
[0008] An irrigation system constructed in accordance with another
embodiment of the invention comprises a conduit for carrying and
dispensing water, at least one mobile tower for supporting and
moving the conduit, and a plurality of wheel assemblies for
supporting the at least one mobile tower. Each of the wheel
assemblies includes a wheel with a central portion and a plurality
of circumferentially spaced mounting elements attached to the
central portion, and each of the mounting elements is movable
between a retracted position and an extended position. An airless
flexible tire is mounted on the wheel and is supported by the
mounting elements when the mounting elements are in the extended
position.
[0009] A method of mounting an airless tire on a wheel in
accordance with yet another embodiment of the invention comprises
moving a plurality of mounting elements on the wheel from an
extended position to a retracted position, positioning the wheel
and the tire such that the wheel is inside the tire, and moving the
plurality of mounting elements from the retracted position to the
extended position such that the mounting elements engage the
tire.
[0010] This summary is provided to introduce a selection of
concepts in a simplified form that are further described in the
detailed description below. This summary is not intended to
identify key features or essential features of the claimed subject
matter, nor is it intended to be used to limit the scope of the
claimed subject matter. Other aspects and advantages of the present
invention will be apparent from the following detailed description
of the embodiments and the accompanying drawing figures.
DRAWINGS
[0011] Embodiments of the present invention are described in detail
below with reference to the attached drawing figures, wherein:
[0012] FIG. 1 is a perspective view of an exemplary irrigation
system including wheel assemblies constructed in accordance with
embodiments of the invention.
[0013] FIG. 2 is a front side perspective view of one of the wheel
assemblies of FIG. 1, the wheel assembly including a collapsible
wheel and a flexible airless tire mounted on the wheel.
[0014] FIG. 3 is a rear side perspective view of the wheel assembly
of FIG. 2.
[0015] FIG. 4 is an exploded view of the wheel assembly of FIG.
2.
[0016] FIG. 5 is a side elevation view of the wheel assembly of
FIG. 2, illustrating a plurality of mounting elements in a
retracted position.
[0017] FIG. 6 is a side elevation view of the wheel assembly of
FIG. 2, illustrating the plurality of mounting elements in an
extended position and engaging the tire.
[0018] FIG. 7 is a fragmentary view of the wheel assembly of FIG.
2, illustrating the mounting elements in the retracted
position.
[0019] FIG. 8 is a fragmentary view of the wheel assembly of FIG.
2, illustrating the mounting elements in the extended position.
[0020] FIG. 9 is a fragmentary, cross-sectional view of the wheel
assembly of FIG. 2.
[0021] FIG. 10 is an environmental side elevation view of the wheel
assembly of FIG. 2 illustrating the wheel assembly mounted on the
irrigation system of FIG. 1 and engaging the ground.
[0022] The drawing figures do not limit the present invention to
the specific embodiments disclosed and described herein. The
drawings are not necessarily to scale, emphasis instead being
placed upon clearly illustrating the principles of the
invention.
DETAILED DESCRIPTION
[0023] The following detailed description of embodiments of the
invention references the accompanying drawings. The embodiments are
intended to describe aspects of the invention in sufficient detail
to enable those skilled in the art to practice the invention. Other
embodiments can be utilized and changes can be made without
departing from the scope of the claims. The following detailed
description is, therefore, not to be taken in a limiting sense. The
scope of the present invention is defined only by the appended
claims, along with the full scope of equivalents to which such
claims are entitled.
[0024] In this description, references to "one embodiment", "an
embodiment", or "embodiments" mean that the feature or features
being referred to are included in at least one embodiment of the
technology. Separate references to "one embodiment", "an
embodiment", or "embodiments" in this description do not
necessarily refer to the same embodiment and are also not mutually
exclusive unless so stated and/or except as will be readily
apparent to those skilled in the art from the description. For
example, a feature, structure, act, etc. described in one
embodiment may also be included in other embodiments, but is not
necessarily included. Thus, the present technology can include a
variety of combinations and/or integrations of the embodiments
described herein.
[0025] Turning now to the drawing figures, and initially FIG. 1, an
irrigation system 10 constructed in accordance with embodiments of
the invention is illustrated and includes a plurality of wheel
assemblies. The illustrated irrigation system 10 is a central pivot
irrigation system that broadly comprises a fixed central pivot 12
and a main section 14 pivotally connected to the central pivot 12.
The irrigation system 10 may also comprise an extension arm (also
commonly referred to as a "swing arm" or "corner arm") pivotally
connected to the free end of the main section 14.
[0026] The fixed central pivot 12 may be a tower or any other
support structure about which the main section 14 may pivot. The
central pivot 12 has access to a well, water tank, or other source
of water and may also be coupled with a tank or other source of
agricultural products to inject fertilizers, pesticides and/or
other chemicals into the water for application during
irrigation.
[0027] The main section 14 may comprise a number of mobile support
towers 16A-D, the outermost 16D of which is referred to herein as
an "end tower". The support towers are connected to the fixed
central pivot 12 and to one another by truss sections 18A-D or
other supports to form a number of interconnected spans. The
irrigation system 10 illustrated in FIG. 1 includes four mobile
support towers 16A-D; however, it may comprise any number of mobile
support towers without departing from the scope of the present
invention.
[0028] Each mobile tower may include a drive tube 20A-D on which a
pair of wheel assemblies 22A-D is mounted. Embodiments of the wheel
assemblies 22A-D are described in more detail below. A drive motor
24A-D is mounted to each drive tube 20A-D for driving the wheel
assemblies 22A-D. The motors 24A-D may include integral or external
relays so they may be turned on, off, and reversed. The motors may
also have several speeds or be equipped with variable speed
drives.
[0029] Each of the truss sections 18A-D carries or otherwise
supports a conduit section 26A-D or other fluid distribution
mechanism that is connected in fluid communication with all other
conduit sections. A plurality of sprinkler heads, spray guns, drop
nozzles, or other fluid-emitting devices are spaced along the
conduit sections 26A-D to apply water and/or other fluids to land
underneath the irrigation system.
[0030] The irrigation system 10 may also include an optional
extension arm (not shown) pivotally connected to the end tower 16D
and supported by a swing tower with steerable wheels driven by a
motor. The extension arm may be joined to the end tower by an
articulating pivot joint. The extension arm is folded inward
relative to the end tower when it is not irrigating a corner of a
field and may be pivoted outwardly away from the end tower while
irrigating the corners of a field.
[0031] The irrigation system 10 may also include one or more high
pressure sprayers or end guns 28 mounted to the end tower 16D or to
the end of the extension arm. The end guns 28 may be activated at
the corners of a field or other designated areas to increase the
amount of land that can be irrigated.
[0032] It will be appreciated that the irrigation system 10 is
illustrated and described herein as one exemplary implementation of
the wheel assemblies 22 described in detail below. Other, equally
preferred implementations of the wheel assemblies 22 not shown or
discussed in detail herein may include, without limitation, other
types of irrigation systems, such as lateral irrigation systems,
other types of agricultural equipment, such as wagons, carts,
implements, and so forth, or other types of vehicles such as buses,
trucks, and automobiles. However, embodiments of the invention are
especially suited for irrigation systems and other vehicles or
systems that travel over unpaved or unfinished ground.
[0033] Referring now to FIGS. 2-10, a wheel assembly 22 constructed
in accordance with embodiments of the invention is illustrated. The
wheel assembly 22 broadly includes a wheel 30 and a flexible
airless tire 32 mounted on the wheel 30 in a generally
circumscribing relationship to the wheel 30. The wheel 30 is
collapsible to facilitate mounting the tire on and removing the
tire from the wheel 30, as explained below. As used herein, a wheel
is "collapsible" if one or more of the portions of the wheel that
engage the tire may be moved radially inwardly to thereby relieve
tension on and/or disengage the tire.
[0034] The wheel 30 and the tire 32 are also configured such that
the tire 32, while being airless, has some characteristics of a
pneumatic tire that improve the performance of the tire. For
example, the wheel 30 and tire 32 are configured such that portions
of the tire 32 flex radially inwardly toward the wheel 30 in
response to ground engaging pressure, as illustrated in FIG. 10. It
will be appreciated that this flexing action increases the total
ground engaging footprint of the wheel assembly 22, thus
distributing the weight of the wheel assembly 22 and the weight of
any machinery supported by the wheel assembly 22 over a larger area
and limiting the total amount of ground penetration of the wheel
assembly 22. Additionally, ground penetration of traction lugs or
other ground-gripping elements of the tire 32 is limited, as
explained below in greater detail.
[0035] As used herein, "ground engaging pressure" refers to
pressure exerted on the wheel assembly 22 by the ground when the
wheel assembly 22 is at rest on the ground or rolling on the
ground. Ground engaging pressure may include pressure exerted on
the wheel assembly 22 from different directions or from multiple
directions simultaneously, such as where the wheel assembly 22 is
on inclined terrain or rolling over an obstacle. Ground engaging
pressure is related to the weight of the wheel assembly 22 and to
the weight of any machinery supported by the wheel assembly 22, and
thus will vary from one embodiment of the invention to another and
from one implementation to another.
[0036] The wheel 30 is configured to engage the tire 32 at
circumferentially spaced locations such that portions of the tire
32 between the points of engagement flex radially inwardly in
response to ground engaging pressure. In the illustrated
embodiment, the wheel 30 includes a disc shaped inner portion 34
and a plurality of circumferentially spaced mounting elements 36
movably attached to a radially outer margin 38 of the inner portion
34. The inner portion 34 of the wheel 30 includes an innermost hub
40 with a plurality of apertures for attaching to, for example, lug
nuts or similar attachment components.
[0037] Each of the mounting elements 36 is movable between a
retracted position (FIGS. 5 and 7) and an extended position (FIGS.
6 and 8). Each of the mounting elements 36 presents an elongated,
transversely oriented radially outer edge 42. When the mounting
elements 36 are in the extended position, the outer edges 42 are
distal the inner portion 34 and engage the tire 32 to thereby
support the tire 32 relative to the wheel 30. When the mounting
elements 36 are in the retracted position, the outer edges 42 are
proximate the inner portion 34. As illustrated, the length of the
outer edge 42 is approximately the same as the width of the tire
32. Furthermore, the outer edge 42 defines a gap 44 configured to
engage a portion of the tire 32 to prevent the tire 32 from
shifting laterally relative to the wheel 30, as explained
below.
[0038] In the illustrated embodiment, each of the mounting elements
36 presents a Y-shape with a lower portion 46 configured to attach
to the outer margin 38 of the wheel 30 and a widening upper portion
48 including the outer edge 42 configured to engage the tire 32. A
slot 50 in the lower portion 46 enables the mounting element 36 to
slidingly engage the outer margin 38 of the wheel 30, and a pair of
through-holes 52 in the lower portion 46 of each mounting element
36 align with a corresponding pair of apertures 54 in the outer
margin 38 of the wheel 30. Bolts 56 or similar connectors are
inserted through the through-holes and the apertures 52 to secure
the mounting elements 36 to the inner portion 34 of the wheel 30.
As illustrated in FIGS. 5 and 6, by removing an innermost one of
the bolts 56, the mounting elements 36 are permitted to pivot about
the other one of the bolts 56, wherein the mounting element 36 is
movable between the retracted position (FIG. 5) and the extended
position (FIG. 6).
[0039] Each mounting element 36 may be constructed of a single,
unitary piece of material, such as metal, that is folded, cast or
otherwise formed to the desired shape and configuration.
Furthermore, all of the mounting elements 36 may be identical in
size and shape. By way of example, each of the mounting elements 36
may be constructed by cutting a piece of metal to a particular flat
shape and then forming the piece of metal to the desired shape
through a series of bending and forming steps. Alternatively, each
of the mounting elements may comprise two or more parts assembled
to form a single structure.
[0040] The mounting elements 36 are approximately equally spaced
around the inner portion 34 of the wheel 30 and extend radially
outwardly from the inner portion 34. When the tire 32 is mounted on
the wheel 30 and the mounting elements 36 are in the extended
position, the mounting elements 36 engage portions of the tire 32
such that the tire 32 is separated radially from the inner portion
34 of the wheel 30 by a space. This configuration allows portions
of the tire 32 to flex inwardly toward the central portion 34 in
response to ground engaging pressure, as explained above. As used
herein, the mounting elements 36 extend radially outwardly from the
inner portion 34 if at least a portion of each of the mounting
elements 36 is positioned radially outwardly of the inner portion
34 of the wheel 30.
[0041] In the illustrated embodiment, the wheel assembly 22
includes ten mounting elements 36 approximately equally spaced
around the outer margin 38 of the wheel 30. If the wheel 30
includes ten mounting elements 36 (as illustrated), the angular
separation of the mounting elements 36 is approximately thirty-six
degrees. Thus, if the wheel 30 is about forty-eight inches in
diameter at the edges 42, the outer edges 42 of the mounting
elements 36 are spaced approximately twelve and one-half inches
apart. If the wheel 30 is about fifty inches in diameter at the
outer edges 42, the mounting elements 36 are spaced approximately
thirteen inches apart at the outer edges 42. If the wheel 30 is
about twenty-four inches in diameter at the outer edges 42, the
mounting element 36 pairs are spaced approximately six inches apart
at the outer edges 42.
[0042] The tire 32 is configured to be mounted on the wheel 30 such
that at least a portion of the tire 32 engages the mounting
elements 36 and the tire 32 presents a generally circular or nearly
circular outer profile. Advantageously, the wheel 30 is configured
for use with an airless tire. As used herein, a "tire" is a
flexible component positioned and configured to engage the ground
during use of the wheel assembly 22. An "airless tire" is a tire
that does not require trapped or compressed air for normal and
proper use. An airless tire may be constructed of a single, unitary
piece of material or multiple pieces of material. As explained
above and illustrated in FIG. 10, the tire 32 is configured to flex
inwardly in response to ground engaging pressure. As used herein,
the tire 32 can "flex" if it can deflect or bend repeatedly and
return to its original shape.
[0043] The illustrated tire 32 includes a body 58 that is generally
cylindrical in shape with a plurality of traction lugs 60 extending
radially outwardly from an outer side of the body 58 and a
plurality of drive lugs 62 extending radially inwardly from an
inner side of the body 58. In the illustrated embodiment, the outer
side 64 of the tire body 58 is generally transversely flat, that
is, the outer side of the body presents little or no curvature from
a first edge to a second edge of the tire. Similarly, the inner
side 66 of the tire body 58 is also generally transversely
flat.
[0044] The traction lugs 60 engage the ground and help prevent the
wheel assembly 22 from slipping relative to the ground. The
illustrated fraction lugs 60 are generally rectangular or
trapezoidal in shape and transversely oriented on the tire 32, are
integrally formed with the tire 32 and may be approximately equally
spaced circumferentially around the outer side 64 of the tire body
58. As illustrated in FIG. 6, the tire 32 may be configured such
that the traction lugs 60 are positioned intermediate the mounting
elements 36. This configuration allows the portion of the tire 32
bearing the traction lug 60 to flex inwardly in response to ground
engaging pressure. This performance characteristic allows each
traction lug 60 to engage the ground, yet limits the amount of
ground penetration and soil disturbance. It may be desirable in
some implementations to position the traction lugs 60 proximate or
in direct radial alignment with the mounting elements 36. Such
alternative configurations of the tire 32 are within the ambit of
the present invention.
[0045] As illustrated in FIG. 6, certain traction lugs 60b may be
larger (i.e., have a greater radial reach) than other traction lugs
60a. In the illustrated embodiment, one of every three traction
lugs has a greater radial reach, corresponding to a position that
is approximately half the distance between consecutive mounting
elements 36. Thus, there are three traction lugs between
consecutive mounting elements 36, with the middle traction lug
being the largest.
[0046] The drive lugs 62 engage the wheel 30 and prevent the tire
32 from shifting longitudinally or laterally on the wheel 30. In
the illustrated embodiment, the drive lugs 62 are arranged in pairs
corresponding to the mounting elements 36 such that the drive lugs
62 are adjacent the mounting elements 36 on opposite sides of the
mounting elements 36. Each of the drive lugs 62 is integrally
formed in the tire 32 and presents a generally elongated body with
a cross member 68 connecting each drive lug 62 pair. Each of the
cross members 68 is located at a center of the tire 32 and
corresponds to the gap 44 defined by the outer edge 42 of the
mounting elements 36.
[0047] The tire 32 is constructed of a flexible material, such as
rubber, PVC or plastic. The tire 32 may be configured such that as
the tire flexes inwardly toward the wheel 30, the flexed portion of
the tire 32 remains transversely flat or substantially transversely
flat. This may be desirable, for example, to preserve a wide
footprint or otherwise limit the amount of ground penetration. With
particular reference to FIGS. 7-9, one or more tension elements 70
may be secured to the tire 32 to give the tire 32 added structural
strength and resilience. As used herein, a tension element 70 is
"secured to" the tire 32 if it is partially or completely embedded
in the tire 32 or otherwise attached or connected to the tire 32. A
first tension element 70a may be placed in a first axial side of
the tire body 58 and a second tension element 70b may be placed in
a second axial side of the tire body 58. Alternatively, a single
tension element may be located in a central portion of the tire 32.
The tension elements 70 are preferably completely embedded in the
tire 32, as illustrated.
[0048] The tension elements 70 are preferably more resilient than
the material used to construct the tire 32 such that the one or
more tension elements 70 increase the overall resilience of the
tire 32, strengthening the structure of the tire 32 and enabling
the tire 32 to return to its original shape after being subject to
deflection during use. The one or more tension elements 70 may be
constructed of metal, such as spring steal, or other resilient and
durable material. More particularly, each of the tension elements
70 may be a metal band constructed of a solid piece of metal or of
multiple bonded or braided metal elements. The tension elements 70
may present a width that is between 0.05 and 0.5 times a total
width of the tire, such as 0.1, 0.2 or 0.3 times the total width of
the tire. If the tire 32 is twelve inches wide, for example, each
of the tension elements 70 may be about two or two and one-half
inches wide and between one-eighth and one-half of an inch
thick.
[0049] The wheel 30 is constructed of a rigid material such as, for
example, metal, plastic or a composite material. The size of the
wheel assembly 22 may vary substantially from one embodiment of the
invention to another without departing from the scope of the
invention. It will be understood that the dimensions and ranges set
forth herein are exemplary, and not limiting, in nature. The
diameter of the wheel 30 is preferably within the range of from
about twenty-four inches to about sixty inches and more preferably
within the range of from about thirty-six inches to about
forty-eight inches. The width of the wheel 30 (i.e., the total
width of each of the mounting elements 36) is preferably within the
range of from about six inches to about eighteen inches and more
preferably within the range of from about eight inches to about
sixteen inches. The diameter of the inner portion 34 of the wheel
30 is preferably between about 0.6 and 0.9 times the total diameter
and may particularly be about 0.8 times the total diameter.
[0050] The thickness of the tire body 58 is preferably within the
range of from about one-half inch to about three inches, more
preferably within the range of from about one inch to about two
inches. The height of the traction lugs 60 is preferably within the
range of from about one-quarter inch to about four inches, more
preferably within the range of from about one-half inch to about
three inches. In one exemplary embodiment, the wheel assembly 22 is
about eleven inches wide and about fifty-two inches in diameter.
The tire body preferably presents a width to thickness ratio of
between five and twenty.
[0051] The collapsible configuration of the wheel facilitates
mounting the tire 32 on the wheel 30 an removing the tire 32 from
the wheel 30. To mount the tire 32 on the wheel 30, for example,
one or more of the mounting elements 36 are placed in the retracted
position to facilitate placement of the tire 32 on the wheel 30. In
the illustrated embodiment, the mounting elements 36 are placed in
the retracted position by removing one of the bolts 56 and allowing
the mounting elements 36 to pivot about the remaining bolt 56. It
may be desirable to place all or most of the mounting elements 36
in the retracted position, but it will be appreciated that in some
circumstances placing as few as one of the mounting elements 36 in
the retracted position is sufficient to accommodate placement of
the tire 32 on the wheel 30.
[0052] When the tire 32 is placed on the wheel 30, the mounting
elements 36 are moved from the retracted position (FIGS. 5 and 7)
to the extended position (FIGS. 6 and 8), thereby causing the
mounting elements 36 to firmly engage the tire 32 and secure the
tire 32 on the wheel 30.
[0053] Although the invention has been described with reference to
the preferred embodiment illustrated in the attached drawing
figures, it is noted that equivalents may be employed and
substitutions made herein without departing from the scope of the
invention as recited in the claims. By way of example, the
particular configuration of the mounting elements 36 that enables
movement between the retracted and the extended positions may vary
from one embodiment of the invention to another without departing
from the spirit or scope of the invention. In addition to the
pivoting configuration illustrated and described herein, the
mounting elements 36 may be configured to slide or otherwise move
between the extended and retracted positions.
* * * * *