| 摘要 |
PROBLEM TO BE SOLVED: To provide a second boom with a cylinder mounting part while maintaining rigidity even if the base end side of the second boom cannot be inserted between a pair of side plates of a first boom. SOLUTION: A main front boom 8 (the second boom) is provided with a pair of side plates 20 for holding the tip of a main boom 6 (the first boom) from both horizontal sides at the base end side, and the pair of side plates 20 are connected in a horizontal direction by a rigid member 23 to form a closed cross section 25 by the rigid member 23 and the side plates 20. The side plate 20 is extended to the opposite side with respect to a boom connecting pin 10 (a horizontal shaft) from a connecting pin insertion part 20b to form a side plate extension part 21, and the cylinder mounting part 26 through which a cylinder support pin 27 for supporting one end of a boom cylinder 11 so as to be turnable is inserted is connected to the side plate extension part 21. At least a part of the cylinder support pin 27 is disposed at the main boom 6 side rather than the closed cross section 25 in a linear direction that connects a boom foot pin 5a (a first boom base end pin) to a horizontal shaft insertion part 20a. COPYRIGHT: (C)2010,JPO&INPIT |
