| 摘要 |
A device for setting the time of actuation of a buzzer or other signal generator in an alarm clock comprises a flexible stem of a manually operable knob, rotatably journaled in two mounting plates, which carries a pinion normally engaging gear teeth of a disk freely rotatable about the hour shaft of the clockwork, the disk being under axial spring pressure urging it against an adjacent hour wheel which has one or more cutouts adapted to receive respective sawtooth-shaped cams on a confronting disk face when the wheel reaches the selected angular position. The user may turn the knob in either direction to advance or delay the selected time setting, except that any delay of 12 hours or more from the time of resetting is prevented by the interengagement of a steep cam flank with an edge of the associated cutout. If the user neverless turns the knob beyond that limit, the stem yields laterally and disengages its pinion from the disk teeth to obviate any damage to the mechanism.
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