| 摘要 |
PROBLEM TO BE SOLVED: To provide a gear capable of improving rotary torque strength and preventing destruction of a wheel gear. SOLUTION: In the gear 10, a disc part 16 formed with a recessed and projecting part 18 is provided on a rotary shaft 12 and the wheel gear 20 molds the whole of the disc part 16. In this case, the wheel gear 20 is bitten and fixed to a portion (the recessed and projecting part 18) having a larger diameter than an outer diameter of a shaft material of the rotary shaft 12. Therefore, total biting area of the rotary shaft 12 and the wheel gear 20 can be increased, even if the diameter of the shaft material of the rotary shaft 12 is not increased, rotary torque strength between the rotary shaft 12 and the wheel gear 20 can be improved, and destruction of the wheel gear 20 due to thinness of a boss part 26 can be prevented. Even if the wheel gear 20 molds the disc part 16 in a gear part 22, the gear part 22 is capable of sufficiently securing radial thickness and thereby, destruction of the wheel gear 20 due to thinness can be prevented.
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