| 摘要 |
PROBLEM TO BE SOLVED: To block the rotation of a plug to an unlocking position and to surely prevent fraudulent unlocking by providing a pickproof pinhole in the radial direction from the inner peripheral face of a case at an offset position from the driver pinhole of the case in the rotating direction of the plug, and providing a pickproof pin intrudably excited by a tumbler pinhole in the pickproof pinhole. SOLUTION: When the outside ends of an outer pin 13 and an inner pin 14 coincide with a shear line to succeed in picking, a plug 9 is rotated in the unlocking direction by the additional torque. However, a pickproof pin 18 is dropped into a tumbler pinhole 11 by the spring force of a spring 20 when the tumbler pinhole 11 reaches the position of a pickproof pinhole 17. When the plug 9 is further rotated and the axes of a tumbler pin 12 and the pickproof pin 18 coincide with each other, the pickproof pin 18 enters the outer pin 13 into a pickproof state to block any more rotation of the plug 9 in the unlocking direction.
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