Hitachi Construction Machinery Co., Ltd.

Wataru Idetsu

Genroku Sugiyama

Yuji Yoshitomi

Akihiko Yamamoto

Osamu Gokita

Kazuyoshi Hatano

Ryohei Suzuki

Akiomi Kono

Yoshiaki Sekiguchi

Prior to forming a thermal spray coating layer ( ) on an end face ( B&prime;) of a structural base material ( &prime;) to be shaped into a boss, firstly an inner masking member ( ) is fitted in an original hole ( A&prime;) of the structural base material ( &prime;) and then an outer masking member ( ) is fitted on outer peripheral side of the structural base material ( &prime;). In the next place, by the use of a hard material, a thermal spray coating layer ( ) is formed on an annular coating area ( B &prime;) which is exposed between the inner and outer masking members ( ) and ( ). Surface areas on the end face ( B&prime;) of the structural base material ( &prime;), corresponding to an allowance range of a machining operation by which the original hole ( A&prime;) is ultimately shaped into a joint pin hole of a specified diameter, are left as a non-coating area ( B &prime;) free of the thermal spray coating layer ( ). Therefore, the original hole ( A&prime;) in the structural base material ( &prime;) can be machined into a final joint pin hole by means of a cutting tool, without experiencing cracking troubles which would otherwise occur to the thermal spray coating layer ( ) during the machining operation.

Method of producing spray deposit on bearing boss

Hardened surface layers ( ) and ( ) of a nitride or other compound, which is higher in hardness than dirt or soil, are formed on the inner peripheral surface ( B) of each metal bush ( ) and on the outer peripheral surface ( A) of each connecting pin ( ) which constitute a crawler belt ( ), respectively. In addition, resinous sliding bearings ( ) are fitted in transversely spaced positions on the inner periphery of each metal bush ( ) of the crawler belt. Bearing ( ) is provided with recessed grooves ( ). Accordingly, part of soil or dirt which intrudes into a gap space between an outer link portion ( ) of a track link and a metal bush ( ) through an annular seal member ( ) is trapped on an inner peripheral surface ( A) of the bearing ( ).

Crawler

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

Crawler belt

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Chiyoda-machi, Japan

Wataru Idetsu