To obtain a thumb-turn extremely effective as a measure against an illegal unlocking act without deteriorating operability for general users.
This thumb-turn comprises a rotating working body 12 connected to a dead bolt drive mechanism and supported on a rotating shaft rotatably about the axis thereof, a shaft 3 for transmitting a rotational force to the rotating working body 12, a handle 5 fixed connected to the end of the shaft 3, a support body 2 supporting the shaft rotatably and slidably along the axis thereof, and a return spring 6 generating a pressing force in a direction apart from the rotatingly working body to the shaft. When the pressing force in an opposite direction exceeding the pressing force of the return spring does not act on the handle, the handle and the shaft 3 are simply rotated idle. On the other hand, when the pressing force in the opposite direction exceeding the pressing force of the return spring 6 acts on the handle 5, the shaft is mechanically connected to the rotating working body 12, and a rotational force acting on the handle is transmitted to a hub to lock or unlock the dead bolt.
YANAGAWA YOSHIAKI
MIURA TADAYOSHI
SATO YUKIO
HOKUSHIN CORP