| 摘要 |
PROBLEM TO BE SOLVED: To relax an impulsive contract surface pressure load when starting a turn table-type rotary drive transmission device.SOLUTION: The center of rotation of a turn table 1 and the center of a kelly rod 4 agree with each other, a gap between a torque transmission surface 11 of the turn table 1 and a protrusion 41 for transmission of a rotary drive force, which is brought into contact with the torque transmission surface 11 of the turn table 1 when the turn table is rotated in the direction of an arrow, is substantially eliminated, and a gap (α) is formed between the side of an opposite surface and the torque transmission surface of the turn table 1. Since the gap is substantially eliminated, an impulsive contract surface pressure load at the rotational starting of the turn table 1 is relaxed, the protrusion 41 for the transmission of the rotary drive force of the kelly rod 4 is hardly damaged, and a use period of the kelly rod can be prolonged to increase economical efficiency. |
