| 摘要 |
PURPOSE:To make a min. display relationship between short and long hands constant, by rotating the short hand by 30 deg. per hour while the long hand is rotated by 390 deg. so that the short and long hands overlap precisely at 0min. and 0sec. each hour. CONSTITUTION:A small drive gear 2 and a large drive gear 3 are fixed on a drive shaft 1. A large gear 4 is for driving a short hand A. For example, the number of teeth is set at 48, and the large gear 4 is meshed with the gear 2. The short hand A is mounted on a gear 4 through a hollow support shaft A1 so that the short hand A will turn together with the gear 4. A small gear 5 is for driving a large hand B. For example, the number of teeth is set at 12 and the gear 5 is meshed with the gear 3. The long hand B is mounted on the gear 5 through a support B1 so that is will turn together with the gear 5. The rotating ratio is set at 1:13 between the short hand A and the long hand B and the ratio of gears is so set that the short hand A turns by 30 deg. per hour while the long hand B turns by 390 deg. per hour. Thus, the long hand B starts rotation with the short hand A overlapping the long hand B at 0min. and 0sec. each hour and at any time, the min. display relationship can be constant between the short hand A and the long hand B.
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