WO1998052776A1

WO1998052776A1 - Tire with improved removable tire tread belt

Info

Publication number: WO1998052776A1
Application number: PCT/US1997/008538
Authority: WO
Inventors: William Earl Rayman
Original assignee: The Goodyear Tire & Rubber Company
Priority date: 1997-05-20
Filing date: 1997-05-20
Publication date: 1998-11-26
Also published as: AU3073197A; JP2001525761A; CA2290472A1; KR20010012738A; ID20313A; ZA983817B; AR012728A1

Abstract

An improved track belt tire is constructed of a removable tread belt assembly mounted to the outer circumferential surface of an inflatable tire carcass. A unique track belt design restrains the track from expanding while simultaneously improving the secure mounting of the track to the carcass and providing improved penetration protection. Also, the improved track belt will maintain a flatter tread profile which in turn will improve tread life and durability.

Description

TIRE WITH IMPROVED REMOVABLE TIRE TREAD BELT TECHNICAL FIELD

This invention relates to pneumatic tires with track belts and more particularly to an improved removable track belt

pneumatic tire constructed of a removable track belt mounted on

an improved radially reinforced beaded tire carcass that is typically for use with earthmoving vehicles.

BACKGROUND OF THE INVENTION

The track belt pneumatic tires of the present invention are

generally designed for use on large earthmover vehicles and are subjected to high stress and loads under harsh environmental conditions such as in rock quarries, mines, foundries, and other areas where tires are subjected to puncture-producing and wear- inducing conditions.

As discussed in U.S. 4,351,380, certain prior art track belt tire assemblies comprise a plurality of ground-engaging shoes spaced about the periphery of the supporting structure.

The heavy loads on the shoes result in great stresses being

developed that sometimes lead to premature tire failure. The 4,351,380 patent is directed to an improved track belt assembly which comprise a plurality of shoes spaced about the periphery

of a load-supporting structure and secured to a reinforcing belt

structure disposed on the side of the shoe opposite the ground- engaging side thereof. The large pneumatic tires, which are typically used for earthmoving vehicles, sometimes fail due to the high stress and

loads caused by the harsh environmental conditions in which they

are operated. These large prior art pneumatic tires had a

greater tendency to fail in one of three tire locations or areas than because of other sources of failure. The first problem

area was that the turnup end of the ply would sometimes break

through the sidewall of the tire. A second problem area was a tire failure in the bead area. The third problem area was a tendency to fail in the crown and/or shoulder area of the tire. In the prior art, conventional solutions to these problems

include increasing the gauge of the sidewall to increase the

bending stiffness, increasing bead area stiffness and robustness, and decreasing tire deformation under load by increasing the sidewall stiffness. To further improve tire durability, the ply turnup portion of tires was typically reinforced.

In U.S. 4,609,023, having a common assignee with the present invention, the sidewall inserts were incorporated in the

tire carcass to allow the ply structure to conform to its

natural shape when the tire is inflated.

With the continual drive to improve earthmover performance, there is a continuing need to provide novel methods and tire

designs for improving earthmover tire durability. The present invention is directed to an improved pneumatic tire and

removable track belt assembly with which the frequency of

premature tire failure is thought to be substantially reduced. The present invention is also directed to providing an improved pneumatic tire and track belt assembly which is designed to allow large tires to be transported in several sections and then

assembled at the construction site to ease the otherwise

difficult problem of transporting the large tires, i.e. sometimes over 13 feet in height and approximately 8,000 to 15,000 pounds. Moreover, the present invention relates to an

improved pneumatic tire and removable track belt assembly with which the driving characteristics of the tire can be more economically changed and the inventory of the number of tire spares that are typically needed can be reduced.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide a pneumatic tire for an earthmover vehicle, the pneumatic tire being as defined in one or more of the appended claims and, as such, having the capability of being constructed to accomplish

one or more of the following subsidiary objects.

It is another object of the present invention to provide an

improved tire and removable track belt assembly for an earthmover vehicle wherein the frequency of premature tire

failure has been substantially reduced. Another object of the present ^"invention is directed to

providing an improved tire and removable track belt assembly

which is designed to allow large tires to be transported in several sections and then assembled at the delivery site. Still another object of the present invention is to provide

an improved tire and removable track belt assembly with which

the driving characteristics of the tire can be quickly and economically changed.

Yet another object of the present invention is to provide

an improved tire and removable track belt assembly with which

the number of tire spares that are stored in inventory can be reduced.

Still another object of the present invention is to provide an improved tire and removable track belt assembly with a unique

track belt that is restrained from expanding radially outwardly. A further object of the present invention is to provide an improved tire and removable track belt assembly wherein the tire

treads will maintain a more flat tread profile which will

improve tread life and durability. A still further object of the present invention is to provide an improved tire and removable track belt assembly wherein the belt is constructed to provide penetration

protection.

In accordance with an embodiment of the invention, an improved track belt tire is constructed of a tire carcass having a plurality of annular lands and grooves formed around the outer circumference of the carcass. A removable track belt assembly is mounted to the outer circumferential surface of tire

carcass to form the track belt tire. The track belt has a plurality of annular lands and grooves formed about the inner

circumference thereof. A plurality of zero degree wires encircle the tire track belt within the annular lands of the

tire tread. The removable tread belt assembly includes a ground contacting tread portion on the outer surface thereof. The tire carcass has a plurality of circumferentially extending lands and grooves oriented to engage complementary ones of the circumferentially extending lands and grooves on the inner

surface of the removable tread belt assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a cross-sectional view illustrating the improved tire with a removable tire tread belt mounted on an inflatable tire carcass and made in accordance with the present invention;

Fig. 2 is an enlarged, cross-sectional view illustrating one side or half of the symmetrical tire shown in Fig. 1 and made in accordance with the present invention;

Fig. 2A is an enlarged, cross-sectional view illustrating

the bead area of the tire shown in Fig. 2; Fig. 3 is a cross-sectional view illustrating an alternative embodiment where the carcass ply turns up axially

inward about a bead wire;

Fig. 4 is an enlarged, cross-sectional view illustrating

one side or half of the symmetrical tire shown in Fig. 3 and made in accordance with the present invention; and

Fig. 4A is an enlarged, cross-sectional view illustrating the turnup portion of the tire carcass shown in Fig. 4.

DEFINITIONS

"Apex" means a non-reinforced elastomer positioned radially about a bead core .

"Aspect ratio" of the tire means the ratio of its section height (SH) to its section width (SW) multiplied by 100% for expression as a percentage.

"Axial" and "axially" means lines or directions that are parallel to the axis of rotation of the tire.

"Bead" means that part of the tire comprising an annular

tensile member wrapped by the ply cords and shaped, with or

without other reinforcement elements such as flippers, chippers, apexes, toe guards and chafers, to fit the design rim.

"Belt or breaker reinforcing structure" means at least two

layers of 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 degrees to 33 degrees with respect to the equatorial plane of the tire.

"Bias ply tire" means a tire having a carcass with

reinforcing cords in the carcass ply extending diagonally across

the tire from bead core to bead core at about 25°-50° angle with respect to the equatorial plane of the tire. Cords run at opposite angles in alternate layers.

"Circumferential" means lines or directions extending along the perimeter of the surface of the annular tread perpendicular

to the axial direction.

"Chafers" refers to narrow strips of material placed around the outside of the bead to protect cord plies from chaffing caused by movement of the rim against the tire.

"Chippers" means a reinforcement structure located in the bead portion of the tire.

"Cord" means one of the reinforcement strands of which the

plies in the tire are comprised.

"Equatorial plane (EP) " means the plane perpendicular to the tire's axis of rotation and passing through the center of its tread.

"Flipper" means a reinforced fabric wrapped about the bead

core and apex.

"Footprint" means the contact patch or area of contact of the tire tread with a flat surface and under load and pressure. "Inner liner" means the layer^" or layers of elastomer or other material that form, the inside surface of a tubeless tire and that contain the inflating gas or fluid within the tire.

"Net-to-gross ratio" means the ratio of the tire tread

rubber that makes contact with the road surface while in the

footprint, divided by the area of the tread in the footprint, including non-contacting portions such as grooves.

"Nominal rim diameter" means the diameter of the rim base

at the location where the bead wire of the tire seals.

"Normal inflation pressure" refers to the specific design inflation pressure at a specific load assigned by the appropriate standards organization for the service condition for the tire.

"Normal load" refers to the specific load at a specific design inflation pressure assigned by the appropriate standards organization for the service condition for the tire.

"Ply" means a continuous layer of rubber-coated parallel cords .

"Radial and "radially" means directions extending radially toward or away from the axis of rotation of the tire.

"Radial-ply tire" means a belted or circumferentially-

restricted pneumatic tire in which the ply cords which extend

from bead to bead are laid at cord angles between 65° and 90° with respect to the equatorial plane of the tire. "Section height (SH) " means the radial distance from the nominal rim diameter to the outer diameter of the tire at its equatorial plane .

DETAILED DESCRIPTION OF THE INVENTION With reference to Fig. 1, there is illustrated a cross- section of improved track belt pneumatic tire 10 which in the specific embodiment illustrated is a size 60/80R63 and/or a

70/68R63 earthmover tire. The size 60/80R63 tire has a 162 inch (411.48 cm) maximum inflated outside diameter, a 60.00 inch

(152.40 cm) maximum inflated width tire in the axial directions, and a nominal bead diameter of 63 inches (160.02 cm) . The size 70/68R63 tire has a 162 inch (411.45 cm) maximum inflated

outside diameter, a 70.0 inch (177.80 cm) maximum inflated width tire in the axial directions, and a nominal bead diameter of 63 inches (160.02 cm). The tires are typically inflated to a pressure of about 100 pounds per square inch (psi) with air and

sometimes with an air/nitrogen mixture.

The improved track belt pneumatic tire 10 includes a ground engaging, circumferentially extending track belt 12 mounted on a radially reinforced, beaded tire carcass 14. The beaded tire

carcass 14 generally includes a pair of tire sidewalls 16,18

extending radially inwardly from the outer circumferential surface 20 of the tire carcass and terminating at their radial extremities in a pair of bead wires 22,24, respectively. The sidewalls 16, 18 each have an upper portion 16a, 18a, respectively, in the shoulder region of tire carcass 14 and

radially inward of the maximum section width of the tire

carcass, and a lower portion 16b, 18b, respectively, adjacent

the bead wires 22, 24, respectively, and radially inward of the maximum section width of the tire carcass 14. The details of the construction of tire carcass 14 are described in detail hereinaf er.

TIRE CARCASS Referring Figs. 1 and 2, the details of tire carcass 14 are illustrated. The axially inward surface 28 is a inner ply liner

26 which forms an innerliner that holds the air pressure for

inflating tire 10. The inner ply liner 26 covers the entire interior facing surface 28 of the tire carcass 14 and serves to hold the air within the carcass that is used to inflate tire 10. Fabric barrier plies 30 and 32 are provided within the tire

carcass 12 in the area of the curved portion of interior surface 28 to provide support for the upper portion of the barrier rubber layer 36 and prevent the barrier rubber from being

squeezed through the ply wires in the ply layer 34. While two

barrier plies 30 and 32 are illustrated, it is within the terms

of the invention to use between one and four barrier plies, as needed for a specific design. The carcass 14 also includes in its construction at least

one rubberized laminated ply layer 34 of tire cord fabric which

extends radially inwardly from the outer circumferential surface

20 of the tire carcass, also called the crown area of the tire carcass, and has turnup ends 34a and 34b which wrap or loop around bead wires 22 and 24, respectively. Although the carcass ply 34 is shown as being of single ply construction, a multi-ply

construction can be employed if desired. Preferably, the carcass ply 34 is made of a rubberized ply of steel cord, but it

can be made of a non-steel carcass reinforcing material. The location of the turnup ends 34a and 34b with respect to the flange 35 of the tire mounting rim 42 and the bead wires 22 and 24, respectively, is a significant aspect of the invention and will be discussed in more detail below. Between the innerliner 26 and the ply layer 34 is a barrier

rubber layer 36 which backs up the entire length of ply layer 34

and is formed of a soft compound of rubber which squeezes against the ply layer 34. Annular stiffeners, known as apexes or apex elements 38,39 herein, each having a generally

triangular shape are provided radially outward of the bead wires

22,24, respectively, and between the barrier rubber 36 and the

innerliner 26. The apexes 38,39 extend from approximately the mid-sidewall and the area of innerliner 26 radially outward from

the bead wires 22, 24, respectively, for stiffening the bead area to help prevent the tire from^" bending over the flange 35.

Axially outward from apexes 38,39 and between the ply layer 34

where it turns up about bead wires 22,24 are located lower gum

chafers 40, 41, respectively, that support the bead wires 22, 24, respectively, in the area of the wheel mounting rim 42 and

to prevent chafing of the tire by an adjacent wheel mounting

rim. Upper gum chafers 44, 45 are disposed against the lower

gum chafers 40, 41, respectively, and the lower tire sidewalls 16b, 18b, respectively, to provide support for the bead wires 22, 24 in the area of the flange 35 and to prevent chafing of the tire by an adjacent wheel mounting rim.

Between the lower chafers 40, 41 and the rubber barrier 36 in the area partially surrounding bead wires 22, 24 are located wire chafer plies 46, 47 that support the bead wires 22, 24,

respectively. As best seen in Figs. 2 and 2A, the wire chafer plies 46 are primarily disposed against the inner facing surfaces of lower chafers 40, 41. Between the inner surface of ply layer 34 and the bead wires 22 and 24 are located flippers

48, 49, respectively, which are reinforced fabric materials that

are wrapped about the bead core and at least a portion of one of

the apexes. On either side of the ends 34a, 34b of ply layer 34

are two wire coat, gum layers 50 and 52 which cover the ends 34a, 34b, respectively, of ply 34 and enable the movement of ply

34 between the gun layers 50 and 52 without exposing the wire within ply 34 during tire construction or severe bending of the tire .

APEX CONFIGURATION

Two annular stiffeners, referred to as apexes 54, 55 herein, each having a generally four sided shape, are provide

radially outward of the bead wires 22,24, respectively, between

flippers 48,49, and out to apexes 58, 59, for stiffening the

area about the bead wires 22, 24, respectively, to help prevent the tire from bending over the flange 35. The apexes 54, 55 are further disposed between the lower inner end of rubberized ply layer 34 and the turn up ends 34a and 34b. Abutted against and extending radially outward from the apexes 54 and 55 are two annular stiffeners, referred to herein as apexes 58 and 59, respectively, which helps support the ends 34a and 34b of

rubberized ply layer 34. The apexes 54, 55, are constructed of

a relatively hard compound having a modulus of about 12.2 - 14.9 megapascals/cm² at 200% elongation. Axially outward from the apexes 58 and 59 are the outer apexes 62 and 64, respectively.

The apexes 38, 39, 58, 59, and 62, 64 are generally constructed of the same relatively soft rubber compound having a modulus of

about 7.2 - 8.8 megapascals/cm² at 200% elongation and act to

provide a soft cushion that absorbs the stresses around the turn

up ends 34a and 34b of the ply layer 34 which is caused by

stress forces generated by the flexing of the tire. While the apexes 38, 39, 58, 59, and 62, 64 are typically constructed of

the same rubber compound,, it is within the terms of the

invention to construct one or more of the apexes with a different modulus within the range of about 7.2 - 8.8

megapascals/cm² at 200 %. In the preferred embodiment, the apexes

38, 39, 58, 60, 62 and 64 are softer than the apexes 54 and 55

which are located directly adjacent and radially outward from the bead wires 22 and 24, respectively. Preferably the rubber compound used to form the apexes 54 and 55 are about 20% to

about 50%, and preferably about 20% to about 50% stiffer than

the rubber compound used to form apexes 38, 39, 58, 59, 62 and 64.

LOCATION OF CARCASS PLY TURNUP ENDS

The location of the ply turnup ends 34a and 34b are an

important aspect of the present invention. As best illustrated in Fig. 2A, preferably the turnup ends 34a, 34b are located

radially outward a distance of between about 2 and 3 bead diameters from the intersection of a centerline 66 which extends

through the center of bead wires 22, 24 and a line 67 which is

tangent to the most radially inward surface of the carcass ply 34 where the carcass ply portions 34a, 34b loop around the wire beads 22, 24 to a line 68 which is perpendicular to centerline

66 and is tangent to the outer end of the ply layer 34. This

location of the outer ends of the turnup ends 34a, 34b of ply layer 34 is important in that it can withstand the pressure exerted against the ply end, which was sometimes sufficient to

cause the ply end to break through the sidewall in prior art

constructions where the turnup ends extend closer to the center of the tire sidewalls. The advantage of having the outer ends of the turnup ends 34a, 34b of carcass ply 34 at a lower

position closer to the radial outward portion of the flange 35

is so that when operating conditions cause the tire to deflect outwards, the ends of turnup ends 34a, 34b of the ply layer 34 will be supported by flange 35. This arrangement will greatly reduce the possibility that the outer ends of turnup ends 34a,

34b will be the cause of a crack in or penetrate axially outward through the sidewall of the tire carcass 14.

NATURAL PLY LINE The ply line of ply layer 34 follows the natural ply line, which means it is already at its natural shape upon inflation.

The carcass ply 34 retains its natural shape when inflated to

reduce the inflation strain on the tire. The portion of the ply cord extending down to the bead 22 is equally supported along

its length by the axially interior surface 37 of the rim flange

35 which is substantially parallel to the centerline 66 passing

though beads 22, 24. Track Bel t

The ground engaging, circumferentially extending track belt 12 is removably mounted onto the tire carcass 14. As best shown in Fig. 2, the underside or inner circumference surface 70 of

track belt 12 comprises a plurality of annular lands 72 and

grooves 74 that mate with lands 76 and grooves 78 of tire carcass 14 to restrain belt 12 from lateral or axial movement with respect to the carcass 14. The tire track belt 12 includes

a tread portion 80 and a plurality of tread belts 82, 84, 86, and 88 (82-88) . While four tread belts 82-88 are illustrated, is it within the scope of the invention to use other numbers of tread plies as needed. The combination of a removable tire track belt with a tire carcass for use with large earthmoving

vehicles is important in that it enables a portion of a tire to be replaced instead of the entire tire in the event that one portion of the tire, i.e., the tire belt or the tire carcass, wears out before the other part. Also, it may be desirable to

have different types of tread designs such as for example

driving or steering tread designs. This feature allows for a less expensive means of changing the tire tread to construct the appropriate style of desired tire. This feature would greatly

reduce the cost of storing spare tires and could even extend the

operating time of the tires. A unique aspect of the present invention is the provision of zero degree wires 90. The zero degree wires 90 encircle the tire tread belt 12 and are provided to restrict the radially

outward growth of the tread belt due to a serious deflection in

the tire carcass. By keeping the tire tread belt from expanding radially outward, the tire treads will maintain a more flat tread profile which will improve tread life and durability. The

zero degree wires 90 will also provide many layers of wire that

will provide cut and penetration protection. The positioning of the zero degree wires 90 within the annular lands 72 of the tire tread 12 has two additional advantages. First, when the tire tread belt 12 is being installed on the tire carcass 14, the tire carcass is inflated and forced outward so that its lands 76

are pressed into the annular grooves 74 disposed about the inner surface of the tire tread belt 12. In the same way, the lands 72 of the tread belt 12 which contain the zero degree wires 90

are pressed into the grooves 78 of the tire carcass 14.

However, since the wires 90 prevent the annular lands 76 from

expanding radially outward from the crown of the tire carcass 14, the lands 76 are pressed into the grooves 70 formed in the

tire belt 12. Since the tire belt 12 can expand slightly more

in the grooves 74 without the zero degree wires 90, the annular

lands 76 have a tendency to press deeper into annular grooves 74 to better support the tire belt 12 on the tire carcass 14. While the zero degree wires 90 are 'illustrated as being in the annular lands 72, it is also within the scope of the invention to include an additional layer of zero degree wire cable

embedded in the belt between the lands 71 and the tread belts

72.

ALTERNATIVE EMBODIMENTS OF TURNUP PLY

An alternative of a tire carcass, such as tire carcass 114,

as illustrated in Figs. 3, 4 and 4A, includes in its construction at least one rubberized laminated ply layer 134 of tire cord fabric which extends radially inwardly from the outer circumferential surface 110 of the tire carcass, also called the crown area of the tire carcass, and has turnup ends 134a and 134b which wrap or loop around bead wires 122 and 124, respectively. Although the carcass ply 134 is shown as being of single ply construction, a multi-ply construction can be

employed if desired. Preferably, the carcass ply 134 is made of

a rubberized ply of steel cord, but it can be made of a non- steel carcass reinforcing material. The location of the turnup ends 134a and 134b with respect to the flange 135 of the tire

mounting rim 142 and the bead wires 122 and 124, respectively,

is a significant aspect of the invention and will be discussed

in more detail below.

Between the innerliner 126 and the ply layer 134 is a barrier rubber layer 136 which backs up the entire length of ply layer 134 and is formed of a soft compound of

rubber which squeezes against the ply layer 134. Annular

stiffeners, known as apex elements or just apexes 138,139 herein, each having a generally triangular shape are provided radially outward of the bead wires 122,124, respectively, and between the barrier rubber 136, the innerliner 126 and the

turnup ply 134. The apexes 138, 139 extend from approximately

the mid-sidewall and the area of innerliner 126 radially outward from the bead wires 122, 124, respectively, for stiffening the bead areas to restrain the tire from bending over the flange 135. Axially inward from apexes 138,139 and between the ply layer 134 where it turns up about bead wires 122,124 are located lower gum chafers 140, 141, respectively, that support the bead wires 122, 124, respectively, in the area of the wheel mounting

rim 142 and to prevent chafing of the tire by an adjacent wheel

mounting rim. Upper gum chafers 144, 145 are disposed against

the lower gum chafers 140, 141, respectively, and the lower tire sidewalls 116b, 118b, respectively, to provide support for the

bead wires 122, 124 in the area of the flange 135 and to prevent

chafing of the tire by an adjacent wheel mounting rim.

Between the lower chafers 140, 141 and the rubber barrier

136 in the area partially surrounding bead wires 122, 124 are

located wire chafer plies 146, 147 that support the bead wires 122, 124, respectively. As best seen in Figs. 3, 4 and 4A, the wire chafer plies 146 are primarily disposed against the inner

facing surfaces of lower chafers 140, 141. Between the inner

surface of ply layer 134 and the bead wires 122 and 124 are located flippers 148, 149, respectively, which are reinforced

fabric materials that are wrapped about the bead core and at least a portion of one of the apexes. On either side of the

ends 134a, 134b of ply layer 134 are two wire coat, gum layers 150 and 152 which cover the ends 134a, 134b, respectively, of ply 134 and enable the movement of ply 134 between the wire

plies 150 and 152 without exposing the wire within ply 134 during tire construction or severe bending of the tire.

APEX CONFIGURATION OF ALTERNATIVE EMBODIMENTS

Two annular stiffeners, referred to as apexes or apex

elements 154, 155 herein, each having a generally four sided shape, are provide radially outward of the bead wires 122, 124, respectively, between flippers 148,149, and out to apexes 158, 159, for stiffening the area about the bead wires 122, 124,

respectively, to help prevent the tire from bending over the

flange 135 of the wheel rim 142. The apexes 154, 155 are

further disposed between the lower inner end of rubberized ply

layer 134 and the turn up ends 134a and 134b. Abutted against

and extending radially outward from the apexes 154 and 155 are

two annular stiffeners, referred to herein as apexes 158 and 159, respectively, which help support the ends 134a and 134b of

rubberized ply layer 134. The apexes 154, 155, are constructed of a relatively hard compound having a modulus of about 12.2 - 14.9 megapascals/cm² at 200% elongation. Axially inward from the apexes 154 and 155 are the inner apexes 138 and 139,

respectively. Axially outward from the apexes 154 and 155 are

the outer apexes 162 and 164, respectively. The apexes 138,

139, 158, 159, and 162, 164 are generally constructed of the same relatively soft rubber compound having a modulus of about 7.2 - 8.8 megapascals/cm² at 200% elongation and act to provide a

soft cushion that absorbs the stresses around the turn up ends 134a and 134b of the ply layer 134 which is caused by stress forces generated by the flexing of the tire. While the apexes 138, 139, 158, 159, and 162, 164 are typically constructed of

the same rubber compound, it is within the terms of the

megapascals/cm² at 200%. In the preferred embodiment, the apexes

138, 139, 158, 159, 162 and 164 are softer than the apexes 154 and 156 which are located directly adjacent and radially outward

from the bead wires 122 and 124, respectively. Preferably the rubber compound used to form the apexes 154 and 156 are about

20% to about 50%, and preferably about 20% to about 50% stiffer than the rubber compound used to form apexes 138, 139, 158, 159,

162 and 164.

LOCATION OF PLY TURNUP ENDS OF ALTERNATIVE EMBODIMENTS

The location of the carcass ply turnup ends 134a and 134b

are an important aspect of the present invention. Preferably,

the turnup ends 24a, 34b are located radially outward. They are looped axially inward of the bead wires 122, 124. This is an improvement of great importance because the pressure of the tire pressing the bead area of the tire carcass 114 against the

flange 135 actually causes the ply ends 134a, 134b to press against the portion of the carcass ply leading axially downward from the crown of the carcass to the bead wires 122, 124. This pressing causes a force which tends to prevent radial movement

of the ply ends 134a, 134b. This in turn tends to added extra support to the sidewalls which helps prevent them from moving in the axially outward directions. Also the bead area around the bead wires 122, 124 is strengthen and the tendency for

rotational movement of the bead wires is reduced because of the effect from pressing the ply ends 134a, 134b against the portion of the carcass ply 134 leading axially downward from the crown

of the carcass to the bead wires 122, 124.

Another innovation with the design illustrated in Figs. 3,

4 and 4A is that the turnup ends 134a, 134b are located a distance of between about 2 and 3 bead diameters from the intersection of a centerline 166 which extends through the center of bead wire 122,. 124 and a line 167 which is tangent to the most radially inward surface of the carcass ply 134 where the carcass ply turn up end portions 134a, 134b loop around the

wire beads 122, 124 to a line 168 which is perpendicular to centerline 166 and is tangent to the outer ends of the carcass ply layer 134. This location of the outer ends of the turnup

ends 134a, 134b of ply layer 134 is important because the

pressure exerted against the ply end was sometimes sufficient to cause the ply end to break through the sidewall in prior art constructions where the turnup end extends closer to the center of the tire sidewall. The advantage of having the turnup ends 134a, 134b of carcass ply 134 at a lower position closer to the radial outward edge of the flange 135 is so that when operating conditions cause the tire to deflect outwards, the ends 134a, 134b of the ply layer 134 will be supported by the ply 134 and

the flange 135. The overall beneficial effect of the looped

axially inward ply layer ends 134a, 134b is a greatly reduced possibility that the turnup ends 134a, 134b will penetrate axially outwards through the sidewall of the tire carcass 114.

While Figs. 3, 4 and 4A illustrate a specific configuration

of apexes 156, 157, 158, 159, 162, 164, flippers 148, 149, as

well as other generally common carcass elements as shown, the looped axially inward ply layer ends 134a, 134b can be incorporated in a radial ply tire with any configuration of apexes, flippers, and other common carcass elements, as required

for the specific type of radial tire. While a track belt

pneumatic tire 100 with a tire track belt 120 mounted onto the

tire carcass 114 can be constructed with looped axially inward ply layer turnup ends 134a, 134b, it is also within the terms of the invention to incorporate the looped axially inward ply layer

turnup ends into a pneumatic tire, such as for example the pneumatic tire shown in the 4,609,023 patent, which is hereby incorporated in its entirety herein. Moreover, while the present invention of incorporating the looped axially inward ply layer turnup ends into a pneumatic tire, such as for example

large pneumatic tires suitable for mounting on earthmoving vehicles, it is also within the terms of the invention to incorporate the inward turnup ply ends for a pneumatic tire suitable for any type of vehicle including but not exclusive

truck, automotive, commercial and residential vehicles.

NATURAL PLY LINE OF ALTERNATIVE EMBODIMENTS

The natural ply line of ply layer 134 follows the natural ply line, which means it is already at its natural shape upon

inflation. The carcass ply 134 retains its natural shape when

inflated, thereby reducing the inflation strain on the tire.

The portion of the ply layer 134 extending down to the beads 122, 124 is equally supported along its length by the axially interior surface 137 of rim flange^" 135 which is substantially parallel to the centerline 166 passing through the center of

beads 122 lnd 124.

Throughout the specification the term rubber compound means any elastomeric compound.

It is apparent that there has been provided in accordance

with this invention apparatus and methods for constructing an improved tire and removable track belt assembly wherein the tire

durability has been substantially increased by the inclusion of an improved apex construction. The improved tire and removable track belt assembly allows large tires to be transported in several sections and then assembled at the delivery site.

Further, the removable track belt assembly allows a different belt to be applied to a tire carcass so as to alter the driving characteristics of the tire quickly and economically. Moreover,

the removable track belt assembly provides a unique track belt that is restrained from expanding radially outwardly whereby the tire treads will maintain a more flat tread profile which in turn will improve tread life and durability. The construction

of the track belt provide improved penetration protection.

While the invention has been described in combination with

embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled

in the art in light of the foregoing teachings. Accordingly, the invention is intended to embrace all such alternatives, modifications and variations as fall within the spirit and scope

of the appended claims .

Claims

What is claimed:

1. A track belt tire, comprising: a tire carcass having a plurality of annular lands and

grooves formed around the outer circumference of the carcass;

a removable track belt assembly mounted to the outer

circumferential surface of tire carcass to form the track belt tire, the track belt having a plurality of annular lands and

grooves formed about the inner circumference thereof; and a plurality of zero degree wires that encircle the tire track belt

within the annular lands of the tire tread.

2. The track belt tire of claim 2 wherein the tire carcass has a plurality of circumferentially extending lands and grooves

oriented to engage complementary ones of the circumferentially

extending lands and grooves on the inner surface of the removable tread belt assembly.

3. The track belt tire of claim 2 wherein the tire carcass is an inflatable, multi-layered carcass.

4. The track belt tire of claim 1 wherein the removable

tread belt assembly includes a ground contacting tread portion on the outer surface thereof.

5. A track belt for mounting to a tire carcass,

comprising:

a removable track belt assembly for mounting to the tire

carcass, the track belt having a plurality of annular lands and grooves formed about the inner circumference thereof; and a

plurality of zero degree. wires that encircle the tire track belt within the annular lands of the tire tread.

7. The track belt tire of claim 5 wherein the removable tread belt assembly includes a ground contacting tread portion on the outer surface thereof .