Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
1999-06-24
2001-07-24
Maki, Steven D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S209130, C152S209220, C152S209260, C152S902000, C152S903000
Reexamination Certificate
active
06263933
ABSTRACT:
TECHNICAL FIELD
This invention relates to a pneumatic agricultural tire for an industrial type tractor or like vehicle.
BACKGROUND ACT
Farm tire designs for industrial service are classified as R-4 service. Overall R-4 service is quite severe and typically involves high loads at a large degree of reading. The vehicles to which the tires are mounted typically are exposed to large amounts of debris, hard packed soil conditions and high load service conditions.
Often times the vehicle has a back hoe bucket or a front skid loader attached to the vehicle. The tires must traverse gravel and broken concrete and hard packed dirt normally. Occasionally the work site can get rain soaked requiring good traction in wet soil conditions.
These tires are generally relatively small and typically have a nominal rim diameter of 28″ (71 cm) or less. They generally have a nonskid depth at the centerline of the tire at approximately 1″ (2.54 cm). A typical tire may be a 400/70R24 tire. This tire when produced in a radial construction will have a carcass with 3 to 4 plies of synthetic cord reinforcement. The cords generally are nylon or polyester. The carcass will further include four belts of high flex polyester, nylon or aramid. Historically, these tires have been all fabric reinforced in order to provide better ride and handling.
There has been a continual tradeoff in attempting to increase the aggressive offroad and tractor performance of these tires while maintaining the treadwear durability and ride requirements. The invention disclosed in this patent application teaches a novel tread that is both comfortable riding, long wearing while also achieving superior offroad traction in both the forward and reverse direction of vehicle travel.
DISCLOSURE OF THE INVENTION
Summary
A radial ply pneumatic tire
20
for industrial service applications is disclosed. The tire has a casing
21
, the casing
21
having at least one ply
22
reinforced by rubber coated cords, a pair of annular extending bead cores
24
, the at least one ply
22
being wrapped about each bead core
24
and extending therebetween, a belt reinforcing structure
28
reinforced with rubber coated cords, and a tread
32
disposed radially outward of the casing
21
. The tread
32
has an inner tread base
34
, two lateral edges
33
A,
33
B the distance halfway between the lateral edges
33
A,
33
B define the tread equatorial plane EP and a plurality of lugs
40
,
50
,
60
extending radially outwardly from the inner tread base
34
.
The tread
32
features three rows of lugs
40
,
50
,
60
. A first row
40
extends axially inwardly from an opposite or a first shoulder region of the tread
32
. A second row
50
extends, axially inwardly from a second shoulder region of the tread
32
. A central row
60
is positioned between the first and second rows
40
,
50
. The lugs
40
of the first row are similar in shape but opposite in orientation relative to the lugs
50
of the second row. Each lug
40
of the first row lies within a first tread half
32
A. Each lug
50
of the second row lies within a second tread half
32
B. The lugs
60
of the central row lie in both the first tread half
32
A and second tread half
32
B. All lugs
40
,
50
,
60
have a leading edge
41
,
51
,
61
and a trailing
42
,
52
,
62
edge. The leading edge
41
of a lug
40
of the first row and a majority of the leading edge
61
of the central lug
60
are defined by a single constant radius of curvature R
1
. The trailing edge
52
of a second row lug
50
and a majority of the trailing edge
62
of the central lug
60
are defined by a, single constant radius curvature R
2
, wherein the origin of the radii of curvature R
1
, R
2
are circumferentially oppositely located in one tread half
32
A or
32
B relative to the other tread half.
Preferably the central lug
60
has enlarged lug head portions
64
,
66
extending from both the leading edge
61
and the trailing edge
62
, both enlarged lug head portions
64
,
66
intersecting the equatorial centerplane EP of the tire
20
.
More preferably, the trailing enlarged lug head
66
of a central lug
60
is connected to a leading enlarged lug head
64
of a circumferentially adjacent central lug head
60
by a reduced height tie bar
70
. The central lug
60
has a radial height h as measured from the inner tread base
34
and the tie bar
70
connecting the lug heads
64
,
66
has a radial height h
T1
of at least 30% h. The lugs
40
of the first row and the axially adjacent central lugs
60
are spaced a distance S less than the minimum width of the lug
40
, within the distance S a tie bar
80
extends between the axially adjacent lugs
40
of the first row and the lugs
60
of the central row, the tie bar
80
having a radial height h
T2
of at least one half the lug height h.
Similarly, the lugs
50
of the second row and the axially adjacent central lugs
60
are spaced a distance S less than the minimum width of the lug
50
, within the distance S a tie bar
80
extends between the axially adjacent lugs
50
of the second row and the lugs
60
of the central row, the tie bar
80
having a radial height h
T2
of less than one half the lug height h.
The radial ply pneumatic tire
20
according to the invention has the net-to-gross ratio as measured around the circumference of the tire less than 50%.
The curvatures R
1
and R
2
when extended to intersect the equatorial plane EP of the tire
20
have tangent lines
90
at the point of intersection which are inclined at an angle &thgr;, &thgr; being less than 60° relative to the equatorial plane. Preferably &thgr; equals less than 45° relative to the equatorial plane.
The leading and trailing edges
41
,
42
,
51
,
52
of the first and second rows of lugs
40
,
50
have tangency lines
92
relative to the curvature R
1
or R
2
at an axially outermost point
45
,
55
along the respective edge, the tangency being inclined at an angle &agr;
o
of about 90° relative to the equatorial plane EP.
DEFINITIONS
“Aspect Ratio” means the ratio of a tire's section height to its section width.
“Axial” and “axially” means the lines or directions that are parallel to the axis of rotation of the tire.
“Bead” or “Bead Core” means generally that part of the tire comprising an annular tensile member, the radially inner beads are associated with holding the tire to the rim being wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes or fillers, toe guards and chafers.
“Belt Structure” or “Reinforcing Belts” means at least two annular layers or plies of parallel cords, woven or unwoven, underlying the tread, unanchored to the bead, and having both left and right cord angles in the range from 17° to 27° with respect to the equatorial plane of the tire.
“Bias Ply Tire” means that the reinforcing cords in the carcass ply extend diagonally across the tire from bead-to-bead at about a 25-65° angle with respect to the equatorial plane of the tire, the ply cords running at opposite angles in alternate layers.
“Carcass” means a laminate of tire ply material and other tire components cut to length suitable for splicing, or already spliced, into a cylindrical or toroidal shape. Additional components may be added to the carcass prior to its being vulcanized to create the molded tire.
“Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction.
“Design Rim” means a rim having a specified configuration and width. For the proposes of this specification, the design rim and design rim width are as specified by the industry standards in effect in the location in which the tire is made. For example, in the United States, the design rims are as specified by the Tire and Rim Association. In Europe, the rims are as specified in the European Tyre and Rim Technical Organization—Standards Manual and the term design rim means the same as the standard measurement rims. In Japan, the standard organization is The Japan Automobile Tire Manufactur
King David L
Maki Steven D.
The Goodyear Tire & Rubber Company
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