| 摘要 |
A digital clock construction, a pinion gear therefor and methods of making the same are provided, the clock construction comprising a frame, first and second time indicating drums each being rotatably carried by the frame, and a pinion gear rotatably carried by the frame and having driving gear teeth disposed in meshing relation with an annular internal gear of the second drum whereby rotation of the pinion gear causes rotation of the second drum, the pinion gear having locking teeth extending from certain of the driving teeth thereof, the first drum having an annular internal locking surface that is adapted to slide against a pair of locking teeth to hold the pinion gear from rotation thereof while the first drum is being rotated through certain timed increments of movement thereof, the first drum having a pair of kicker teeth for meshing with the driving teeth of the pinion gear to rotate the pinion gear when the first drum is being rotated through a particular one of the timed increments of movement thereof, the first drum having a relief in the locking surface thereof that is located adjacent the kicker teeth thereof for receiving one of the locking teeth therein as the pinion gear is being rotated by the kicker teeth, the locking teeth each having a part thereof that is adapted to cooperate with the relief to prevent any substantial rotation of the pinion gear in one direction thereof after the first drum has completed the particular timed increment of movement thereof and that respective locking tooth is in alignment with the relief so as to be out of engagement with the locking surface.
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