PNEU RENFORCE

HIGH LOAD BEARING CAPACITY PNEUMATIC TIRE

Abrégé anglais

HIGH LOAD BEARING CAPACITY PNEUMATIC TIRE
ABSTRACT
The heavy duty, high load capacity tire has
a reinforcement belt that includes two to four unfolded
plies made of steel and/or Aramide cord and a fettering
ply, made of 5° to 15° steel cord, arranged in the central
portion of the reinforcement belt radially outward of the
two to four unfolded plies. The fettering ply clamps
the unfolded plies in the area of the tread center firmly
onto the crown area of the carcass to maintain a low radius
of curvature in the crown area of the carcass in a non-
inflated condition, or under normal inflation pressures.

Revendications

-5-
What is claimed is:
1. A heavy duty, high load bearing capacity pneumatic
tire comprising, in cross-section, a tread, a radial carcass
having at least one ply formed of steel cords, and a multi-
ply belt-like reinforcement disposed between the tread and
the carcass, said reinforcement including a plurality of un-
folded radially internal plies on the crown area of the car-
cass, and an unfolded radially external fettering ply formed
with steel cords and being of lesser cross-wise extent than
the radially internal plies for firmly clamping the radially
internal plies to the crown area of the carcass, the radially
internal plies having cords making a bias angle in the range
of 16° to 32°, with respect to a circumferential center-line
of tread and being arranged to intersect at each sequen-
tial ply and wherein the bias angle of the fettering ply with
respect to the circumferential center line of the tread is
in the range of 5° to 15°, to maintain the crown area of the
carcass in a substantially flat shape in an uninflated condi-
tion and when the tire is inflated to normal operating pres-
sures, and wherein the cords in the radially outermost ply
of said radially internal plies, and the cords in said fet-
tering ply are inclined such that their respective inter-
sections with the origin of a pair of coordinate axes,
wherein one of said axes correspond to the circumferential
center line of the tread, are capable of forming respective
angles lying in one quadrant of said coordinate axes.
-5-

-6-
2. A tire as claimed in claim 1 wherein the
radially internal plies comprise steel cords.
3. A tire as claimed in claim 1 wherein the radially
internal plies comprise Aramide cords.
4. A tire as claimed in claim 1 wherein there are
three radially internal plies.
5. A tire as claimed in claim 4 wherein the radially
internal plies are of different cross-wise extent.
6. A tire as claimed in claim 5 wherein the
middle ply of the three radially internal plies is of
greater cross-wise extent than the other radially internal
plies.
7. A tire as claimed in claim 6 wherein the outer-
most ply of the three radially internal plies is of shorter
cross-wise extent than the innermost ply of the three
radially internal plies.
8. A tire as claimed in claim 1 wherein the bias
angle of the radially internal plies is in the range of 18°
to 24°.
9. A tire as claimed in claim 1 wherein the tire has
sidewalls joined to opposite end portions of the tread and a
pair of adhesive rubber cushions are arranged at the end
portions of the tread beneath the marginal areas of the rein-
forcing belt.
-6-

-7-
10. A tire as claimed in claim 6 wherein the middle
ply of the three radially internal plies has a cord angle
such that the cord is inclined in another quadrant upon inter-
secting at the origin of the coordinate axes with the fettering
ply and the radially outermost ply of the radially internal
plies.
-7-

Description

10866~
This invention relates to pneumatic tires and more
particularly to a heavy duty, high-load capacity pneumatic
tire for trucks or other large size vehicles.
O~e known high load capacity tire as shown in U. S.
Patent 3,757,844 (Corresponding to DOS 2,162,847) employs
a reinforcement comprising a folded belt ply having a cord
angle of 15 enclosing an unfolded belt ply having a cord
angle of 22 . Another unfolded belt ply having a cord
angle of 18 is disposed between the folded free ends of the
lo 15 ply, all plies being made of steel cord. This reinforce-
ment is particularly stiff at the belt edges and at the
shoulder areas.
rires such as shown in U. S. Patent 3,757,844 when
mounted to a heavy vehicle, can usually be operated with-
out damage for an extended period of time at a speed of
120-130 kilometers per hour (75 to 81.25 miles per hour).
However, the tire carcass undergoes considerable deflection
between the sidewall areas of maximum width. Consequently
there is a relatively low radial elevation of the tire tread
above the rim, usually lower than that of a standard pneumatic
tire for heavy vehicles which often results in pronounced
wear of the tire in the shoulder area.
In large, heavy duty, high load bearing capacity
pneumatic tires it is desirable to keep the tire cross-
section flat not only during its manufacture but also when
it is inflated to normal operating pressure.
It is known in the art to impart a pre-selected
profile to a radial carcass to enable it to adapt to the
flat profile o~ a reinforcement belt that is incorporated
therein. However the principal ob~ect of this invention is
to obtain a flat cross-section in a standard radial carcass

--2--
solely as a result of the reinforcement belt design,
thereby simplifying tire manufacture and also providing
improved wear characteristics particularly in the shoulder
area of the tire. Other ob~ects and features will be in
part apparent and in part pointed out hereinafter.
In accordance with the invention a radial tire is
provided with a belt like reinforcement that includes two
to four unfolded plies made of steel cord and/or Aramide
cord and a "fettering" ply externally spanning parts of
at least one of the other plies and having 5 to 15 steel
cords. Preferably the steel cord fettering ply is arranged
in the central portion of the reinforcing belt and, pre-
ferably all other plies are situated radially within the steel
cord fettering ply. Under this arrangement the fettering
ply clamps the unfolded plies in the area of the tread
center firmly onto the crown area of the carcass.
The accompanying drawing shows a fragmentary cross-
section of a pneumatic tire incorporating one embodiment o~
my invention.
Referring now to the drawing the pneumatic tire is
generally indicated by reference number 1 and a central
circumferential plane of the tire 1 is indicated by the
reference letter A. The intersection between the central
circumferential plane A and the tire tread defines a central
circumferential line of the tread.
The tire 1 includes a radial carcass 2 preferably
made of steel cords. Although the carcass 2 is shown to be
of single ply construction it is also feasible to use a
carcass having more than one ply. The carcass 2, in its
sidewall areas, is covered by sidewall rubber plies 3 extend-

16)~66~9
--3--
ing bilaterally into the shoulder areas 6 and 7 of a
tread 5. The inner area of the tire is designated by
the reference number 4.
A belt like reinforcement 8 is disposed between the
tread 5 and the crown area of the carcass 2 and bears
upon the carcass 2 along both sides of the central cir-
cumferential plane A.
A pair of adhesive rubber cushions 11 and 12 are
-- arranged beneath the marginal areas of the belt like rein-
forcement 8.
The belt like reinforcement 8 comprises two to four
unfolded plies of steel or Aramide cord layered one upon the
other such as the plies 13, 14 and 15. The cord elements
in the plies 13, 14 and 15 make an angle between 16 and
32, preferably between 18 and 24 with the circumferential
center line of the tread. However the cord elements in
sequential plies intersect with one another.
It should be noted that the plies 13, 14 and 15 can
all be formed with either steel cord or Aramide cord, or
sequential plies can be formed of alternate stated materials.
A fettering ply 16 made of steel cord is layered
directly onto the ply 15 and covers the central area of the
plies 13, 14 and 15. The ply 16 thus clamps the central
area of the plies 13, 14 and 15 to the carcass 2, the
fettering effect being achieved by arranging the cord elements
in the ply 16 at a bias angle of approximately 5 to 15
with the circumferential center line of the tread.
A clamping in of the central area of all the
plies 13, 14 and 15 is preferred and it is not necessary that
the fettering ply extend the full width of the plies 13,
14 and 15. As shown in the drawing, the plies 13, 14 and
15 can be of different axial width and the ply width in a
--3--

1086619
--4--
radlal direction need not be equivalent. If desired,
more than three of the plies such as 13, 14 and 15
can be used.
It has been found that upon vulcanization of
the disclosed tire construction and also upon inflating
the tire to normal operating pressure the crown area
of the carcass has a low radius of curvature and retains
a generally flat cross-sectional shape. The flatness
extends to a larger area of the unfolded belt plies and
carcass cro~Jn than is encompassed by the fettering ply.
me fettering ply thus permits a firm and durable application
of the unfolded belt plies to the crown area of the carcass.
Thus the provision of the steel cord fettering ply
enables large size and high load bearing capacity pneumatic
tires to be maintained cross-sectionally flat in a simple
efficient manner. Since the shoulder cross-section is
substantially smaller than corresponding shoulder areas
of conventional pneumatic tires for trucks it generates
less interior heat during operation resulting in reduced
wear of the shoulder.
In view of the above, it will be seen that the
several objects of the invention are achieved and other
advantageous results obtained.
As various changes could be made in the above con-
struction without departing from the scope of the invention,
it is intended that all matter contained in the above
description or shown in the accompanying drawing shall be
interpreted as illustrative and not in a limiting sense.