| 摘要 |
PROBLEM TO BE SOLVED: To enhance rigidity of a connection part between a rear boom constituent body and a front boom constituent body, and to enable inexpensive manufacturing of the boom saving constituent materials of the boom. SOLUTION: The boom formed to be a chevron shape which is bent at the longitudinal directional center part in a manner of protruding upward comprises the front boom constituent body which is on a front side of the longitudinal directional center part, the rear boom constituent body which is on a rear side of the longitudinal directional center part, and a center connecting plate connecting a rear end side of the front boom constituent body to a front end side of the rear boom constituent body. The rear end side of the front boom constituent body and the front end side of the rear boom constituent body are connected to each other with vertical deviation. COPYRIGHT: (C)2008,JPO&INPIT
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