| 摘要 |
The present invention relates to a percussion hammer for enlarging drilled holes. The hammer comprises an external outer wear sleeve (5), an inner cylinder (7) mounted co- axially within the outer wear sleeve (5) , a tubular torque shaft (3) disposed axially and centrally of the hammer assembly, and extending longitudinally through the assembly. The hammer further comprises a sliding piston (6) mounted for reciprocating movement within the inner cylinder (7) and outer wear sleeve (10) and about the tubular torque shaft (3) to strike a hammer bit (1) for reciprocal movement in a chuck (4) adjacent a forward end of the hammer assembly. The hammer bit (1) has a central bore (46) through which the torque shaft (3) extends, such that the torque shaft (3) protrudes forwardly of the hammer. |
