Wheel substitutes for land vehicles – Tracks or treads – Separate transverse connector pin between treads
Reexamination Certificate
2000-12-22
2002-07-23
Stormer, Russell D. (Department: 3617)
Wheel substitutes for land vehicles
Tracks or treads
Separate transverse connector pin between treads
C403S317000
Reexamination Certificate
active
06422667
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a structure for fixing links and pins of a traveling crawler chain to be used in a crawler-type vehicle. More particularly, it relates to a link-and-pin fixing structure for a crawler chain, which enables the links and the pins to be fixed to each other easily and firmly and in which the links and pins can be assembled securely at a low cost.
2. Description of the Related Art
Plural ground-contact track shoes are mounted to an endless link chain with mounting bolts in a traveling crawler chain of a crawler-type vehicle of construction machine such as a bulldozer or a hydraulic shovel. For assembling this link chain, pins for connecting links, which are press-fitted into cylindrical bushes respectively, are press-fitted into the respective end portions of right and left links successively. The cylindrical bushes have their respective both ends exposed outside. The end portions of the respective links are coupled with each other with pins in an articulated manner such that they are part from each other. The end portion of each link is provided with a lubricant-sealing member and its crush-preventing spacer for preventing internal abrasion between the pin and the bush. Lubricant reserved within the pin is supplied to between the pin and the bush.
Generally, the aforementioned link chain is used for travelling on hard, soft ground composed of soil, sand, gravel or the like or hard, soft slope ground of such. Therefore, the link chain interferes with outside obstacles, rocks or the like. Thus, the respective links tend to receive an external force in their axial direction through a flange or the like of a lower roller of the vehicle. Additionally, end faces of the pins also tend to receive an external force or the like in their axial direction through a roller guard or the like of the vehicle body, so that the pin becomes loose easily. If the pin is held with a small force, it may start or come out. Thus, the lubricant-sealing member and the crush-preventing spacer of the sealing member disposed at the end portions of the links are easily deformed, starts to be displaced or damaged.
If the sealing member or the crush-preventing spacer of the sealing member is damaged, consumption speed of the lubricant is accelerated so that an internal abrasion occurs between the pins and the bushes to damage the pins or bushes. As a result, the function of the link chain is lost in a short period. Thus, the links and the pins are fixed to each other by a strong press-fit in order to prevent the link and the pin from being moved in their axial direction by an external force. Furthermore, there has been employed a mechanism for preventing the pins from coming out of the link.
As this pin-coming-out preventing mechanism, for example, Japanese Patent Application Publication No. 5-79548 discloses a link-and-pin fixing structure.
In this conventional fixing structure, each link is provided with an annular socket having a diameter-expanding slope surface directed outward in the axial direction, at an outside end face of a pin-press-fit hole. An exposed end portion of the pin has an annular groove dented smoothly inward in the axial direction of the link from its end face. Thus, when the pin is pressed into the pin-press-fit hole of each link, there is formed an annular hollow portion having an opening inclined outward between the groove in the pin and the socket of the link.
Then, an annular pressing-in retainer for preventing come-out of the pin, which is made of metallic material, is pressed into the annular hollow portion through its opening between the pin-press-fit hole in the link and the exposed end portion of the pin. The pressing-in retainer is plastically deformed along an inner wall of the hollow portion so that the hollow portion is filled with the retainer. By employing this slip-out preventing mechanism, there is an advantage that a moving of the pin in its axial direction can be suppressed.
Meanwhile, when a joint composed of the link and the pin is repaired, the pin is pushed out from the end portion of each link and the pressing-in retainer is cut out. Then, the cut-out pressing-in retainer is taken out of the hollow portion. Next, an end portion of the pin is press-fitted into the pin-press-fit hole of the link and a new pressing-in retainer is brought into the opening of the hollow portion. Consequently, the hollow portion is filled with the new pressing-in retainer similarly to above.
However, according to the above described Japanese Patent Application Publication No. 5-79548, the annular pressing-in retainer is pressed into the annular hollow portion as being plastically deformed so that the hollow portion is filled with the deformed pressing-in retainer. Thus, the pressing-in retainer needs to be filled securely between a surface of the groove in the pin and an inner face of the socket of the link. That is, if the filled annular pressing-in retainer is not fitted locally between the groove surface of the pin and the inner face of the socket of the link, it is easily peeled off. Consequently, a holding force of the pin in the axial direction is decreased to make the pin loose easily. Thus, durability cannot be expected.
Therefore, a complicated machining, a high dimensional precision and the like are required. Further, it is necessary to adjust positions of the socket of the link and the groove in the pin accurately, which requires more equipment cost, production cost and the like, as well as strict quality control. However, it is impossible to visually check an internal shape of the deformed and filled pressing-in retainer in the hollow portion. Therefore, not only in assembling of the link and the pin, but also in an inspection after the assembling work, it is not possible to see whether or not the deformed pressing-in retainer is fitted securely to the wall of the hollow portion. Thus, quality of products can not be uniform, and defective products are often produced.
SUMMARY OF THE INVENTION
The present invention has been accomplished to solve the above-described conventional problems. An object of the present invention is to provide a link-and-pin fixing structure of a crawler chain that makes it possible to fix the link and the pin to each other securely and firmly and secure a holding force for holding the pin sufficiently in its axial direction. Further, the present invention has an object to produce a link-and-pin fixing structure of a crawler chain that allows assembling of the link and the pin to be carried out easily at a low cost.
The above-described object is achieved effectively by following features of the present invention.
Firstly, according to the present invention, there is provided a link-and-pin fixing structure of a crawler chain, wherein a fitting space having an annular opening, in which an elastic ring whose diameter of a section is D is to be fitted, is formed between an opening end portion of a pin-press-fit hole of a link and a press-fit end portion of a pin exposed in the opening end portion; a link inner wall of the fitting space is formed with an tapered inner-diameter face whose diameter gradually decreases as it goes toward an inmost of said fitting space such that the tapered inner-diameter face intersects an axial line of the pin at a predetermined angle &agr;; an outer peripheral face of the exposed end portion of the pin exposed in the fitting space is formed with an tapered outer-diameter face whose diameter gradually decreases as it goes toward the inmost of said fitting space such that the tapered outer-diameter face intersects the axial line of the pin at a predetermined angle &bgr;; said tapered inner-diameter face intersects an inner-diameter surface of said pin-press-fit hole at said angle &agr; via an inner annular face continuous to said tapered inner-diameter face, and said tapered outer-diameter face intersects said inner-diameter surface of said pin-press-fit hole at said angle &bgr; via an outer annular face continuous to said tapered outer-diame
Bell Boyd & Lloyd LLC
Komatsu Limited
Stormer Russell D.
LandOfFree
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