| 摘要 |
PROBLEM TO BE SOLVED: To suppress abrasion of both the inner surface of a recessed portion 19a and a cylindrical projecting surface 14 by ensuring the contact area of the inner surface of the recessed portion 19a formed in the outer surface of an outer ring 18a composing a thrust ball bearing 17a with the cylindrical projecting surface 14 formed on a support beam 15 composing a trunnion 9a, and to ensure durability of the thrust ball bearing 17a by suppressing elastic deformation of the outer ring 18a. SOLUTION: The recessed portion 19a is formed to have a Gothic arched cross section with a pair of side recessed curved surface portions 29, 29 smoothly continued to each other through a center recessed curved surface 30. The radii of curvature r<SB>29</SB>of the cross-sectional shapes of both the side recessed curved surface portions 29, 29 are set larger than the radius of curvature r<SB>14</SB>of the cylindrical projecting surface 14, and the radius of curvature r<SB>30</SB>of the cross-sectional shape of the center recessed curved surface 30 is set smaller than the radius of curvature r<SB>14</SB>of the cylindrical projecting surface 14. The recessed portion 19a and cylindrical projecting surface 14 are allowed to abut in both the side recessed curved surface portions 29, 29. COPYRIGHT: (C)2011,JPO&INPIT
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