| 摘要 |
Hardened surface layers (12) and (14) of a nitride or other compound, which is higher in hardness than dirt or soil, are formed on the inner peripheral surface (11B) of each metal bush (11) and on the outer peripheral surface (13A) of each connecting pin (13) which constitute a crawler belt (7), respectively. In addition, resinous sliding bearings (15) which are each formed of an ultra-high molecular weight polyethylene-base resin are fitted in transversely spaced positions on the inner periphery of each metal bush (11) of the crawler belt. The resinous sliding bearing (15) is provided with a plural number of recessed grooves (16) on and around its inner periphery as axially extended grooves. Accordingly, part of soil or dirt which intrudes into a gap space between an outer link portion (9) of a track link and a metal bush (11) through an annular seal member (17) is trapped on an inner peripheral surface (15A) of the resinous sliding bearing (15) in an embedded state, while remainder of the intruding soil is trapped in the recessed grooves (16).
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