| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent a structure disposed at the inside of a boom from being damaged by foreign matters advancing between boom members. SOLUTION: On an upper surface 5bt and a side surface 5bv of a base end part in an intermediate boom 5b fitted into base end booms 5a, an upper surface member 21 and a side surface member 22 which are projected toward internal surfaces of the opposed base end booms 5a and are provided with inclined surfaces 21a and 22a inclined in an elongating and contracting direction of a boom 5 are mounted. Therefore, foreign matters advancing into the boom 5 without being removed by a scraper disposed at a tip part of the boom 5 are led as shown in arrows A, B, C, D in a Figure, discharged to the outside of the boom 5, mixed into a hose sheave 18 and does not damage the hose sheave 18, when the boom 5 performs a raising and laying operation on a pivotal shaft 51.</p> |
