To provide a thumb-turn device preventing unfair unlocking wherein the thumb-turn shaft of the thumb-turn device can not be turned in the unlocking direction by an unfair unlocking means.
The thumb-turn device 10 is provided with a thumb-turn shaft 12 for protruding and retracting a dead bolt 3 through a hub 4, a lock pin 20 urged so as to project to the base end and provided at the base end of the thumb-turn axis 12, a thumb-turn body 30 rotatably holding the thumb-turn shaft 12 without allowing the shaft to move in the axial direction and having a recess 35 restricting the rotation of the thumb-turn shaft 12 by intrusion of the base end of the lock pin 20, and a knob 40 provided at the base end part of the thumb-turn shaft 12 to be movable in the axial direction in the condition urged to the tip side in the axial direction, containing the base end side head of the lock pin 20 and having a head containing groove 44 transferring the lock pin 20 to the tip side in the axial direction according to the peripheral directional rotation against the urging force.
Koyama
Masayuki Mukai
Kazunori Omotani