| 摘要 |
PROBLEM TO BE SOLVED: To provide an elastic boom for previously preventing damage to an actuation control valve at an inexpensive cost. SOLUTION: An elastic boom 30 has a boom bracket 31 journaled to the tip of an elastic boom 11, a linking member 40 journaled to the bracket 31, and a tip bracket 33 journaled to the tip part of the member 40. The member 40 has a pair of lower arms 43 arranged at given gaps in a horizontal direction in the bracket 1, an upper arm 41 arranged between a pair of arms 43 in plan view, an elastic cylinder 49 pivotally connected between the bracket 31 and the arm 41, and an actuation control valve 55 fitted to the side wall of the cylinder 49. The valve 55 can not be protruded outside from the boom 30 even the cylinder 49 is elastically actuated to oscillate the boom 30 in a vertical direction to the bracket 31.
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