| 摘要 |
PURPOSE:To prevent foreign matter from being caught, prolong the life of bearing, prevent seizure during initial period and prevent noise form being produced by forming at least the rolling members of a rolling bearing for supporting a gear shaft out of ceramic. CONSTITUTION:Lubricating oil passes through the gear mechanism 8a and the bearing 2 on an upper gear shaft 5, flows on the inner circumferential surface of a case 1, passes through the lower side gear mechanism 8b and bearings 3, 4, and flows down to the lower part of the case 1. The bearings 2, 3, and 4 comprise an inner race 10, an outer race 11, a rolling member 12, and a holder 13 for holding the rolling member 12 respectively. The rolling members 12 are made of ceramic. Because the rolling contact surfaces are of different materials from each other, seizure is restricted even if the amount of lubricating oil is insufficient and roughening of the rolling contact surfaces due to adhesion is lessened. Even if foreign matter enters the bearing, the foreign matter is not caught with the rolling members 12. Therefore, an exfoliation phenomenon due to impression is restricted.
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