JP4162160B2 - Heavy duty radial tires for track running - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heavy duty radial tire for track running used as a main wheel of a subway, a monorail, and a new transportation system vehicle.
[0002]
[Prior art]
In recent years, radial heavy-duty tires for track running have come to be used as main wheels of subways, monorails, and new transportation systems from the standpoint of vibration ride comfort. Such tires have a low floor by flattening to reduce the outer diameter of the tire in order to realize an increased load capacity, and a flat so-called smooth pattern is adopted for the tread pattern to travel on a flat track. ing. The measurement of the wear amount of the smooth pattern has heretofore been performed using a wear amount measurement hole provided in the tread. For example, a plurality of hole groups opened in the tread surface are arranged in the circumferential direction of the tire, the depth is reached to the wear limit, and the wear amount is measured by such holes. Moreover, a hole described in Japanese Utility Model Publication No. 56-26971 is known as a technique for preventing the occurrence of cracks due to these holes.
[0003]
[Problems to be solved by the invention]
However, the conventional hole for measuring the wear amount of the smooth pattern has a problem of causing uneven wear.
[0004]
Accordingly, an object of the present invention is to provide a heavy duty radial tire for track running with a tread wear amount measuring means capable of preventing the occurrence of uneven wear without impairing various performances of the tire.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, a heavy duty radial tire for track running according to the present invention includes a pair of bead portions, a carcass connected to the bead portion in a toroid shape, and a tread disposed on a crown portion of the carcass. In a radial heavy duty tire for track running with an aspect ratio of 80% or less,
A pair of left and right regions extending from both ends of the tread to 25% to 15% of the tread width are arranged in the circumferential direction, one straight groove, and no other groove is present in the tread. The groove width of the groove is 4 to 8 mm, and the curvature radius R of the groove bottom is 2 to 4 mm.
[0006]
In the radial heavy duty tire for track running, it is preferable that the linear groove is formed perpendicular to the tread surface.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the heavy duty radial tire for track running according to the present invention, as shown in FIG. 1, one linear groove 2 is formed in each of a pair of left and right regions extending from both ends of the tread 1 to 25% to 15% of the tread width. It arrange | positions in the circumferential direction and the abrasion loss of the tread of a smooth pattern is measured by this groove | channel.
[0008]
If such a straight groove is disposed in a region exceeding 25% from the tread end (region closer to the center of the tread), the effect of suppressing uneven wear from the shoulder end is reduced, while a region less than 15% (region closer to the shoulder). If it arrange | positions to, the distortion of a groove bottom will increase and it will become easy to generate | occur | produce a crack. These relationships are shown in FIG.
[0009]
Moreover, in this invention, it is preferable that the groove width of the said linear groove | channel is 4-8 mm, and the curvature radius R of a groove bottom is 2-4 mm. If the groove width is less than 4 mm, the groove bottom R is also reduced, and the groove bottom distortion tends to increase during load rolling. On the other hand, if it exceeds 8 mm, the wear volume of the tread is reduced and the wear life is reduced. .
[0010]
Furthermore, in the present invention, by forming the linear groove perpendicular to the tread surface, it is possible to correct the imbalance of groove bottom distortion during loading.
[0011]
The radial heavy-duty tire for track running according to the present invention relates to improvement of the means for measuring the amount of wear of the smooth pattern, and the tire structure other than the arrangement of the linear grooves is a track running with a conventional flatness ratio of 80% or less. It is not necessary to change from a heavy duty radial tire for heavy duty use, and can be manufactured in accordance with conventional practice.
[0012]
【Example】
Hereinafter, the present invention will be specifically described based on examples.
A prototype of a heavy duty radial tire for track running that satisfies the following conditions was tested. As a result, it was found that there was little distortion at the groove bottom and uneven wear near the shoulder was suppressed to a satisfactory level.
(1) Tire size: E275 / 75R17.5
(2) rim size (internal ^{pressure): 8.25-17.5 (10.4Kg / cm 2} )
(3) Tread width: 210mm
(4) Position of linear groove: Position of 20% of the tread width from both ends of the tread (5) Curvature radius R / groove width / groove depth of linear groove: R3 mm, 6 mm, and 8 mm
[0013]
【The invention's effect】
As described above, in the groove for measuring the amount of tread wear provided in the radial tire for heavy duty use for track running according to the present invention, cracks are caused by increasing the groove bottom distortion without impairing various performances of the tire. Therefore, the occurrence of uneven wear can be suppressed.
[Brief description of the drawings]
FIG. 1 is an enlarged partial cross-sectional view showing a tread portion of an example tire of the present invention.
FIG. 2 is a graph showing a relationship between a linear groove position, a partial wear suppression effect, and a groove bottom strain suppression effect.
[Explanation of symbols]
1 Tread 2 Straight groove

Claims (3)

In a heavy duty radial tire for track running having a flat rate of 80% or less, comprising a pair of bead portions, a carcass continuous in a toroidal shape with the bead portions, and a tread disposed on a crown portion of the carcass,
A pair of left and right regions extending from both ends of the tread to 25% to 15% of the tread width are arranged in the circumferential direction, one straight groove, and no other groove is present in the tread. A radial heavy duty tire for track running, wherein the groove width of the groove is 4 to 8 mm and the curvature radius R of the groove bottom is 2 to 4 mm. The linear groove track traveling for heavy duty radial tire according to claim 1 Symbol placement are formed perpendicularly to the tread surface.   The radial tire for heavy loads for track running according to claim 1 or 2, wherein the linear groove is a groove as a tread wear amount measuring means.

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