Bearing device

Abstract

A dust seal (20) has a fitting tube section (20A), a bush end surface contacting section (20B), a lip section (20D), and a seal protrusion (20E) which are integrally formed together. The seal protrusion (20E) is formed so as to protrude from a radially inner portion of the bush end surface contacting section (20B) in a direction axially opposite to the lip section (20D) and makes contact with andcovers a chamfered section (14E) of a bush (14). When a lubricating agent such as grease is supplied between the bush (14) and a connecting pin (17), the seal protrusion (20E) prevents a part of the lubricating agent from entering between an end surface (14D) of the bush (14) and the bush end surface contacting section (20B) of the dust seal (20), and this maintains a gap between the end surface (14D) and the bush end surface contacting surface (20B) in a sealed state. The construction enables the dust seal (20) to be stably held on the inner peripheral side of a boss member (12) to prevent extrusion of the dust seal (20) caused by lubricating agent supplying pressure.

Description

technical field [0001] The present invention relates to a bearing device suitable for use in a pin coupling portion of a working device such as a hydraulic excavator, and more particularly to a bearing device provided with a dust seal for suppressing entry of foreign matter from the outside. Background technique [0002] Generally, a construction machine such as a hydraulic excavator is provided with, for example, a work device that is located on the front side of the vehicle body and is composed of a boom, an arm, and a bucket for excavation work such as sand and soil. The boom of the work device Bearing devices are provided between the arm and the arm, between the arm and the bucket, etc., so that the two can be rotatably connected to each other. [0003] This prior art bearing device includes: a cylindrical hub member provided on any one of the above-mentioned boom, arm, and bucket, the inner peripheral side of which serves as a sleeve fitting hole; A sleeve in the sleev...

AI Technical Summary

Problems solved by technology

However, if the protrusion-shaped anti-dropping part is formed on the outer peripheral side of the fitting cylinder part, it takes extra man-hours to form the dust seal using a metal mold or the like, and it takes extra man-hours when the mold is ejected, which reduces the anti-dropping effect. The problem of the forming and processing workability of the dust ring

In addition, there is a possibility of uneven sealing force due to uneven fitting force due to the protrusion-shaped anti-removal part.

[0009] In addition, even if such a drop-off prevention part is added to the fitting cylinder part of the dust seal, due to the pressing force of the lubricant entering the side of the sleeve end face abutting part, there is a possibility that the dust seal will move from the sleeve to the sleeve. The direction in which the end face of the seal is separated, that is, the case where it is pushed toward the opposite part, so there is a problem that the anti-slip effect of the dust seal cannot be fully expected.

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