Wheel substitutes for land vehicles – Endless belt having nonmetallic track or tread – Track formed of endless flexible belt
Reexamination Certificate
2000-03-03
2003-05-27
Stormer, Russell D. (Department: 3617)
Wheel substitutes for land vehicles
Endless belt having nonmetallic track or tread
Track formed of endless flexible belt
C305S165000, C305S167000
Reexamination Certificate
active
06568769
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an elastic flat tread for an endless crawler belt, which is used for a hydraulic shovel, bulldozer, and other construction equipment, and particularly, to an elastic flat tread with improvements in the shapes and the materials of a core and an elastic solid covering the core.
BACKGROUND ART
Conventional construction equipment such as hydraulic shovels and bulldozers with steel crawler belts being, attached has the disadvantage of damaging asphalt road surfaces when traveling on a public road on the move between work sites, and therefore increasing number of vehicles are equipped with rubber crawler belts recently.
The rubber crawler belts are formed by a number of core wires and cores embedded in rubber in an endless shape, but if problems such as a crack and peeling, of rubber occurs, it is difficult to repair them, which necessitates the replacement of the crawler belt to a new one, thereby causing the disadvantage of increasing user cost.
In order to overcome the foregoing disadvantage, elastic flat treads formed by iron crawler plates with elastic solids such as rubber being bonded thereto are used. Recently, an art is developed, in which a core is embedded into an elastic solid to construct an elastic flat tread, a plurality of which are disposed in a longitudinal direction of a crawler to thereby form an endless crawler belt.
As a prior art of an elastic flat tread, for example, Japanese Patent Application Laid-open No. 7-152305 is known, which will be explained with reference to FIG.
53
and FIG.
54
. In an elastic flat tread
140
, a planar core
120
is covered with an elastic solid
130
from the entire ground-contacting side toward core end portions
121
and
121
in a longitudinal direction of the core
120
on the side not in contact with the ground, and bonded thereto by vulcanization. The core
120
is fastened to a link
150
by bolts not illustrated. Numeral
132
is a bolt hole for insertion of the bolt.
However, in the above elastic flat tread
140
, as shown in
FIG. 55
, elastic solid end portions
131
are locally bent to thereby cause the concentration of stress, when the elastic flat tread
140
runs on a protruding object such as a rock or stone A and a curb stone of a sidewalk not illustrated. As a result, the disadvantage of a crack P occurring in the elastic solid end portion
131
is caused. This is because the core
120
is designed to have high rigidity so as not to be deformed even if the vehicle weight W of construction equipment is exerted on the elastic flat tread
140
via a lower roller
145
and a link
150
.
Meanwhile, even the elastic solid
130
with higher rigidity in nature has lower rigidity than that of the core
120
. Consequently, when running on a protruding object such as a rock or stone A and a curb stone of a side walk, so long as the protruding object does not escape therefrom, distortion concentrates on the elastic solid
130
due to the difference in rigidity between the core
120
and the elastic solid
130
, thereby causing the crack P in the elastic solid end portion
131
shown in FIG.
55
.
Further, the head portions of bolts fastening the core
120
and the link
150
contact the elastic solid
130
, thus causing the disadvantage that a crack and peeling occur at the bolt insertion holes
132
.
DISCLOSURE OF THE INVENTION
The present invention is made in view of the disadvantages of the prior art, and its object is to provide an elastic flat tread capable of preventing an elastic solid from cracking when a vehicle runs on or collides with a rock or a stone, or a curb stone of a sidewalk during traveling.
In order to attain the above object, a first aspect of an elastic flat tread according to the present invention is an elastic flat tread having links of which end portions are connected to the adjacent end portions in a traveling direction of a crawler with a pin, and a core covered with an elastic solid at least on the ground-contacting side, and characterized in that
the aforesaid core is any core of a core attached to the aforesaid link and a core attached to a metal plate which is attached to the aforesaid link, and in that
end portions in a longitudinal direction of the aforesaid any core are bent toward the side not in contact with the ground.
According to the above structure, even if the vehicle runs on or collides with a protruding object such as a rock or stone, or a curb stone of a sidewalk, since the end portions in a longitudinal direction of the core are bent toward the side not in contact with the ground, the rock or stone escapes from the elastic solid end portion formed along the bent portion of the core, thus making it possible to avoid local concentration of stress on the elastic solid. When the angle of bend of the core end portion is made larger, even if the elastic solid end portion formed along the bent portion collides with a curb stone of a sidewalk, local concentration of stress on the elastic solid can be avoided. The angle of bend of core end portion is appropriately set in the range of 10 degrees to 90 degrees, and the angle of bend of the core end portion is set in consideration of the weights of various kinds of models small to large in size, the sizes of the elastic flat treads, the lengths in the longitudinal direction of the cores, and the like. For example, in a small-sized model which frequently operates in a working site with many small rocks and stones, the angle of bend of the core end portion may be made smaller, and in a large-sized model which frequently operates in a working site with many large rocks and stones, the angle of bent of the core end portion may be larger. Consequently, even if the vehicle runs on a protruding object such as a rock or stone, or a curb stone of a sidewalk during traveling, a crack does not occur in the elastic solid end portion, thus increasing durability of the elastic flat tread.
A second aspect of the invention is characterized in that at least one layer of cable layers is provided inside the aforesaid elastic solid, under the aforesaid any core, near an end portion in a longitudinal direction of the aforesaid any core, in the structure of the first aspect of the invention.
According to the above structure, in addition to the operational effects of the first aspect of the invention, the cable layer is embedded near the end portion in a longitudinal direction of the core, thereby increasing the rigidity at this portion, which eliminates the occurrence of a crack in the elastic solid even if the elastic solid end portion runs on or collides with an protruding object such as a rock or stone, or a curb stone of a sidewalk. Consequently, durability of the elastic flat tread is improved, which makes the elastic flat tread useful to construction equipment operating in various working sites.
A third aspect of the invention is characterized in that a direction in which cable wires of the aforesaid cable layers are placed is either one of the parallel and diagonal directions relative to the longitudinal direction of the aforesaid any core, or the combination of two directions or more selected from the parallel and diagonal directions, in the structure of the second aspect of the invention.
According to the above structure, the elastic solid is strengthened by the cable layer with the direction of the cable wires being either one of or two or more of the parallel and diagonal directions relative to the longitudinal direction of the core, and therefore a crack does not occur in the elastic solid even if the elastic solid end portion runs on or collides with a protruding object such as a rock or stone, or a curb stone of a sidewalk. Consequently, durability of the elastic flat tread is improved, which makes the elastic flat tread useful to construction equipment operating in various working sites.
A fourth aspect of the invention is characterized by including a synthetic resin member which is placed near the end portion in the longitudinal direction of the aforesaid any core, and which is fixed to the afor
Hori Kazutoshi
Tagawa Tomihiro
Taira Kenji
Watanabe Hiroaki
Yamamoto Teiji
Armstrong Westerman & Hattori, LLP
Komatsu Ltd.
Stormer Russell D.
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