Abstract: Prior to forming a thermal spray coating layer (28) on an end face (23B′) of a structural base material (23′) to be shaped into a boss, firstly an inner masking member (32) is fitted in an original hole (23A′) of the structural base material (23′) and then an outer masking member (33) is fitted on outer peripheral side of the structural base material (23′). In the next place, by the use of a hard material, a thermal spray coating layer (28) is formed on an annular coating area (23B1′) which is exposed between the inner and outer masking members (32) and (33). Surface areas on the end face (23B′) of the structural base material (23′), corresponding to an allowance range of a machining operation by which the original hole (23A′) is ultimately shaped into a joint pin hole of a specified diameter, are left as a non-coating area (23B2′) free of the thermal spray coating layer (28).

Abstract: 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) are fitted in transversely spaced positions on the inner periphery of each metal bush (11) of the crawler belt. Bearing (15) is provided with recessed grooves (16). 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 bearing (15).

Abstract: 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.

Abstract: Prior to forming a thermal spray coating layer (28) on an end face (23B′) of a structural base material (23′) to be shaped into a boss, firstly an inner masking member (32) is fitted in an original hole (23A′) of the structural base material (23′) and then an outer masking member (33) is fitted on outer peripheral side of the structural base material (23′). In the next place, by the use of a hard material, a thermal spray coating layer (28) is formed on an annular coating area (23B1′) which is exposed between the inner and outer masking members (32) and (33). Surface areas on the end face (23B′) of the structural base material (23′), corresponding to an allowance range of a machining operation by which the original hole (23A′) is ultimately shaped into a joint pin hole of a specified diameter, are left as a non-coating area (23B2′) free of the thermal spray coating layer (28).

Abstract: The present invention concerns a crawler belt (7) incorporating a sealing devices (21), which are each constituted by a coned disc spring (23) and a seal ring (22), to seal up gap spaces between track links (8) and bushes (13). A seal anchor hole (12) is provided in each one of outer link portions (9) of track links (8) of the crawler belt (7), and the sealing device (21) is fitted in the seal anchor hole (12) between an outer link portion (9) and an opposing end face (13A) of a bush (13). The sealing device (21) includes the seal ring (22) in the shape of an O-ring, and the coned disc spring (23) which is arranged to press the seal ring (22) resiliently against peripheral wall surface (12B) of the seal anchor hole (12) and the end face (13A) of the bush (13).