| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent a boom from being damaged due to the collision of a boring hammer lifted by a mobile crane therewith. Ž<P>SOLUTION: A guide sheave 8 and a top sheave 9 are provided at the front end of a lattice boom 5 which is supported on an upper structure 4 and derrickable. A sling 11 for supporting the boring hammer 12 is suspended from the hoist rope 10 wrapped around the guide sheave 8 and the top sheave 9. An elastic damping body 22 is attached to the front surface side of the lattice boom 5 which faces the hammer 12. The direct collision of the hammer 12 with the lattice boom 5 is avoided by colliding the hammer 12 with the damping body 22 when the hammer 12 moved upward is swung, and an impact force is absorbed by elastically deforming the damping body 22 when the hammer 12 is collided with the damping body 22 to prevent the lattice boom 5 from being damaged. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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