Large size tires for trucks and other heavy vehicles

Abstract

Abstract A large size tire particularly adapted for trucks and other heavy vehicles, the tire being one that is reinforced by a radial or standard casing of cords turned in the bead in open plies around a single wire, the tire being one in which the turned-back portion of the cords follows a direction substantially parallel to that of the traction cords opposite thereto, the bead being stiffened above the wire to the level of the rim by a core of rubber having a shore hardness greater than 80, said core being covered with a further rubber core having a shore hardness in the order of 55 to 60. Generally, the length of the turned-back portion of the cords forming the open ply is as slight as possible, the end of the turned-back cords being turned slightly outward. The present invention is directed to an improvement in large size tires for trucks and other heavy vehicles, and more particularly to an improvement in such large size tires for trucks and other heavy vehicles wherein such tires are reinforced by a radial or crossed casing of cords, such cords being turned back in ''''open'''' plies around a single wire surmounted by a hard rubber core. In the past years there have been many improvements made in the construction of tires. Thus, for example, improvements progressively made in the characteristics of the textile materials used in the manufacturing of tires have made it possible to reduce the thickness of the walls of the tires while attaining equal service characteristics. This improvement has itself been supplemented, for example, by the use of larger and larger cords for reinforcements, thereby making it possible to considerably reduce the number of plies necessary in the manufacture of the tires. Such improvements which have been developed in the past are both of considerable value for tires of standard structure (i.e., those having side layers making an angle between them) and for tires with a radial casing since they offer the manufacturers great possibilities in reducing the cost of tires by allowing the use of less raw materials in tire production. However, although such improvements previously developed are of considerable value in such standard tires as described, the same are not satisfactory with respect to truck tires and similar tires subjected to very heavy loads. In this regard, the use of truck tires having thin walls and a single wire shows anomalies in the zone of the bead resulting in a severe limitation of the life of the tire. Thus, since such tires with thin walls are very flexible in the zone of the beads, it is as though a shock wave were destroying the construction of the beads slightly above the level of the edge of the rim where the tire is subjected to heavy loads such as truck tires are subjected to. This effect is even more pronounced at the point at which the turned back plies end. This effect is particularly noticeable in the case of tires for heavy loads reinforced with synthetic textiles, i.e., polyamides, polyesters, etc., rayon with a high tensile strength, or cords of glass. Generally, in tires with textile or glass reinforcement, the plies are turned around a wire, imprisoning a core of rubber locAted above the wire. Such plies come almost in contact with the traction layers by forming ''''closed'''' plies. When used, the destruction of tires used in this manner occurs generally in a zone close to the end of the turned layers in a manner which makes it often visible on the inside traction plies. While various attempts have been made to improve such generally employed structure, such attempts have for the most part been unsuccessful especially with respect to truck tires and tires employed for other high-load uses. Thus, for example, various attempts have been made to increase the size and length of the core located above the wire about which the plies are turned, the folded layers of plies still being brought very close to the traction layers. While in some respects better results have been obtained as the filling cores located above the wire have been progressively increased, in the case of large radial tires with one or two plies on the side the results are insufficient for industrial use contemplated. Accordingly, with respect to truck tires and similar tires subject to heavy loads, any improvements resulting from the increase in the size and length of the core located above the wire have not been satisfactory for the purposes to which the tire is subjected. Accordingly, it has long been the desire of the art of tire production to provide a structure for large size tires, e.g., truck tires and other tires subjected to heavy loads, which would eliminate the inherent deficiencies and disadvantages associated with previously employed structures. This has now been accomplished in accordance with the present invention, whereby a tire can be produced having wearing characteristics and strength characteristics far in excess of those possessed by conventional tires. This is accomplished in accordance with the present invention by providing a tire for trucks and other heavy vehicles wherein such tire is reinforced by a radial or standard casing of cords turned in the bead, in open plies, around a single wire, so that the turned back portion of the cords follows a direction substantially parallel to that of the traction cords opposite thereto, the bead being stiffened above the wire to the level of the rim edge by a core of rubber with a shore hardness greater than 80. By such a structure a tire is produced which has an unexpectedly high-wearing ability and unexpectedly high ability to withstand the stresses associated with heavy loads. It is accordingly a principle object of the present invention to provide a novel large size tire for trucks and similar heavy vehicles, which tire eliminates the inherent deficiencies and disadvantages of prior art structures. It is a further object of the present invention to provide a large size tire for trucks and similar heavy vehicles wherein such tire is reinforced by a radial or crossed casing of cords, the cords being turned back in ''''open'''' plies around a single wire surmounted by a hard rubber core. It is still a further object of the present invention to provide a novel large size tire for trucks and other heavy vehicles, such tire being reinforced by radial or standard casing of cords turned in the bead, in open plies, around a single wire, so that the turned back portion of the cords follows a direction substantially parallel to that of the traction cords opposite thereto. It is still a further object of the present invention to provide such tire wherein the bead is stiffened above the wire to the level of the rim edge by a core of hard rubber with a shore hardness greater than 80, and then, above this level a second rubber core with a shore hardness greater than 80, and a third rubber core with a shore hardness of about 55 to 60.

Inventors

• 👤 Raymond J Guyot

Bibliographic Details