Wheel substitutes for land vehicles – With means to remove or exclude foreign matter – With seal between connector pin and track link
Reexamination Certificate
2002-04-19
2003-09-02
Morano, S. Joseph (Department: 3619)
Wheel substitutes for land vehicles
With means to remove or exclude foreign matter
With seal between connector pin and track link
C305S204000
Reexamination Certificate
active
06612663
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a fastening structure between a link and a pin of a crawler belt in a vehicle such as a construction machine.
BACKGROUND ART
A crawler belt utilized in a construction machine, such as a bulldozer and a hydraulic shoveling machine, comprises an endless annular link chain provided with shoes (crawler shoes) for contact with ground. The link chain has such a structure that a plurality of links are interconnected by pins. A structure of the link interconnection is shown in FIG.
8
. As shown in this figure, the link chain includes a predetermined number of link pairs of a left-hand and a right-hand links
31
,
32
disposed in a longitudinal direction. In each of the link pairs
31
,
32
, a pin
33
and a bushing
34
fasten an end portion of a longitudinally preceding link pair to a front portion of the following link pair. More specifically, the pin
33
is inserted into the bushing
34
, and the bushing
34
is press-fitted into rear holes
41
a
,
42
a
of the preceding links
31
a
,
32
a
, whereas the pin
33
is press-fitted into front holes
41
b
,
42
b
of the following links
31
b
,
32
b
. Since the bushing
34
and the pin
33
are pivotable, the preceding and the following links
31
a
,
31
b
are connected with each other in a bendable manner like a joint. It should be noted here that, in
FIG. 8
, a portion indicated by numeral
35
is a lubricating oil supplying hole. Lubricating oil supplied here provides lubrication between the pin
33
and the bushing
34
.
According to the crawler belt described as above, the pin
33
is subjected to a large force in a direction of thrust during use. Therefore, according to the link chain described as above, a retaining mechanism for preventing the pin
33
from coming out of the links
31
,
32
is provided (for example, U.S. Pat. No. 4,618,190). According to this fastening structure between link and pin, an annular recess is formed around an opening of the pin insertion hole in the link. Further, close to an end portion of the pin, a circumferential groove smoothly recessing in an axially inward direction is formed. The recess in the link and the groove in the pin form a cavity having an annular opening, between the circumferential edge of the opening of the pin insertion hole and the outer end portion of the pin. Into this cavity, there is driven an annular retainer made of a metal for preventing the pin from coming out. The retainer is plastically deformed to conform to the shape of the cavity, so as to fill the cavity with the retainer, thereby preventing the pin from relative, disengaging movement out of the link toward the side away from the opening.
Now, with the above described fastening structure between link and pin, in order to prevent development of an excessive play between the link and the pin, the plastic deformation of the retainer must be carried out sufficiently so that the retainer is tightly fitted to conform to the shape of the annular cavity. However, in order to achieve this, there is a need for complex machining operation, and a high dimensional accuracy in the product. In addition, the recess of the link and the groove of the pin must be aligned with each other accurately, which leads a problem of increased cost of facility and equipment as well as cost of manufacture.
In an attempt to solve the above described problem, the Japanese Patent Application No. Hei 11-182264, for example, proposes a fastening structure of link and pin, in which a retaining ring
36
is employed. Specifically, as shown in
FIG. 9
, an annular space
45
is formed between a circumferential edge of an opening of pin insertion holes
41
b
,
42
b
of the links
31
,
32
and a corresponding end portion of a pin
33
. The retaining ring
36
is disposed in this space
45
, thereby preventing the relative, disengaging movement of the pin
33
toward the side away from the opening. In this case, there is formed a tapered inner surface
43
having a diameter gradually increasing from the pin insertion hole
41
b
toward outside, surrounding the opening of the pin insertion hole
41
b
. On the other hand, the pin
33
is formed with a tapered outer surface
44
facing the tapered inner surface
43
. A slanting angle of the tapered outer surface
44
, with respect to the axis, is slightly smaller than a slanting angle of the tapered inner surface
7
. With this arrangement, the tapered surfaces
43
,
44
are farther away from each other in the outward direction. The retaining ring
36
is made of an annular elastic metal having a circular section, with a part of the ring cut out so that the ring can elastically spread and shrink in diameter.
However, the above described fastening structure between link and pin of a crawler belt has the following problems resulting from that the opening portion of the pin insertion hole
41
b
of the link
31
and the outer end portion of the pin
33
are tapered surfaces
43
,
44
respectively, and that the retaining ring
36
has a circular section. Specifically, first, assembling operation is costly. More specifically, since the section of the retaining ring
36
is circular, the ring circumferential surface cannot have a sufficient area of contact with each of the tapered surfaces
43
,
44
, being unable to obtain sufficient initial friction from the elastic restoring force of the retaining ring
36
alone. For this reason, in an assembling step, an operation of driving the retaining ring
36
inwardly is necessary. For this particular operation of driving the retaining ring
36
, a special jig dedicated to the pressing operation must be prepared. Further, a pressing apparatus capable of providing a necessary level of driving force is necessary. As a result of these, a high cost is required for the assembling operation.
Secondly, in order to achieve a desired friction as after the assembling, the tapered inner surface
43
and the tapered outer surface
44
have to be machined to a high accuracy. Specifically, if the angle made by the two tapered surfaces
43
,
44
is too large, the retaining ring
36
cannot be held by the friction and moves away, becoming unable to provide the expected function. For example, in the state shown in
FIG. 9
, it has been confirmed that the angle &thgr; between the tapered surfaces
43
,
44
must be smaller than 20° approximately. As a result of such a high machining accuracy required of each part, manufacturing cost of these has to increase.
The present invention is made to solve the above described problems, with an object to provide a fastening structure between link and pin of a crawler belt which can be assembled by simple operation at a low cost, without requiring a high machining accuracy, and thus can be manufactured at a low cost.
DISCLOSURE OF THE INVENTION
Now, a fastening structure of link and pin of a crawler belt according to a first invention is a fastening structure of a link and a pin in a crawler belt of a vehicle. An annular space
15
is formed between a circumferential edge of an opening of a pin insertion hole
5
of a link
2
and an outer end portion of a pin
1
to be inserted in the pin insertion hole
5
, and a retaining ring
3
is disposed in the space
15
whereby preventing relative, disengaging movement of the pin
1
toward a side away from the opening. The structure is characterized in that one of the circumferential edge of the opening of the pin insertion hole
5
of the link
2
and the outer end portion of the pin
1
is formed with a tapered pressure receiving surface
8
having a diameter gradually decreasing in an axially inward direction, the other is formed with a pressing portion
7
, and the retaining ring
3
is formed with a friction surface
9
to be press-contacted to the pressure receiving surface
8
by a force from the pressing portion
7
upon development of the relative movement in the disengaging direction. It should be noted here that the pressing portion
7
may be an edge portion as in the first embodiment through the third embodiment, or may be a tapere
Hashimoto Akira
Nakaishi Hiroyuki
Yamamoto Teiji
Armstrong Westerman & Hattori, LLP.
Komatsu Ltd.
Morano S. Joseph
Nguyen Long Bao
LandOfFree
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