Single-tooth gear 1 rotates about fixed axis A-A. Gear 2 has eight teeth and rotates about axis B of toothed casing 3. After being rotated seven revolutions, winding shaft A-A is stopped when the tooth of gear 1, rigidly mounted on the shaft, runs against the concentric surface of tooth a on gear 2. As the main spring mounted on axis A-A runs down, casing 3 rotates in the direction opposite to the one required in winding the spring. At this, gear 2 rolls around single-tooth gear 1. For each revolution of casing 3, gear 2 turns one tooth with respect to its axis B.
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