| 摘要 |
PROBLEM TO BE SOLVED: To solve various problems of the conventional method such as noise, damping of an impact force, the strength of a drill rod, and the adaptability to a construction site all at once, while highly efficiently excavating by applying a striking force to a bit. SOLUTION: This excavator is provided with an outer tube 1 and an inner bit assembly 2 stored in the outer tube 1. The inner bit assembly 2 is provided with a down-the-hole hammer 6, front part and rear part clamp devices 7 and 8 connected to the front/rear portions of the down-the-hole hammer 6, and having engagement members 62 and 36 operating in the radial direction respectively and detachably engaged with the internal circumference of the outer tube 1, and an inner bit 9 to be engaged with the axial front portion of the front part clamp device 7.
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