| 摘要 |
There is provided a resin gear 1 capable of improving the strength of a key receiving portion, which is engageable with a key of a driving shaft, to prevent the key receiving portion from being broken by external force applied during rotation. In the resin gear 1 , an outside rim 6 is connected to an inside hub 4 by a web 7 in radial directions. On the side of one end of the hub 4 , a key receiving portion 10 for engaging a key of a driving shaft 2 is formed. The key receiving portion 10 has a side wall 1 for preventing relative rotation of the key 8 to the hub 4 , and a bottom wall 12 for allowing the key 8 and hub 4 from being positioned in directions parallel to the driving shaft 2 . An inside web 7 a, which is a portion of the web 7 surrounding the hub 4 and key receiving portion 10 , is arranged so that a contact point P at which the wide wall 11 of the key receiving portion 10 contacts the key 8 is substantially arranged on a plane which includes the center of the inside web 7 a in thickness directions and which is parallel to the inside web 7 a.
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