| 摘要 |
PROBLEM TO BE SOLVED: To permit the expanding and contracting action of a gripper shoe and that of a shield jack, without damaging the shield jack placed within the gripper shoe, by preventing muck from entering the gripper shoe. SOLUTION: A shield jack 9 stored in a gripper shoe 7a can expand and contract, together with a spread 9a at its end, in the direction to bore a tunnel, and the rear end of the shield jack 9 is attached to the front plate of the gripper shoe 7a. An opening 7b having almost the same shape as the spreader 9a is provided in the rear plate of the gripper shoe 7a, and the spreader 9a fits into the opening 7b when a gripper is used. |
