| 摘要 |
<p>The present invention relates to a boom assembly for a crane. The boom assembly for a crane includes: a main boom; and multiple inserting booms which are coupled to the inside of the main boom in order to be inserted or withdrawn. The boom assembly for a crane comprises: a front-end operating unit including a first cylinder which inserts or withdraws a first inserting boom from the main boom when the first inserting boom through the N inserting boom (N: natural number >= 3) are inserted into the main boom consecutively, a second cylinder which inserts or withdraws a second inserting boom from the first inserting boom, a first valve block which controls the flow of a fluid that operates the first cylinder; and a back-end operating unit including a third cylinder which inserts or withdraws a third inserting boom from the second inserting boom, and a second valve block which controls the flow of a fluid that operates the third cylinder. In addition, the first valve block and the second valve block operate independently from each other.</p> |
