| 摘要 |
PROBLEM TO BE SOLVED: To improve the strength of a long lower rail, ensure a bolting space at the bottom of the long lower rail, and bolt the long lower rail to a floor through an opening in the long lower rail. SOLUTION: A long lower rail 12 has a roller receiving step portion 12f formed on each side of the bottom of a body portion 12a. An upper rail 13 includes a body portion 13a and a vertical wall 13e projecting from the middle of an upper wall 13d upward beyond an opening 12e. A roller 27 is inserted between the bottom step portions 12f of the body portion 12a of the long lower rail 12, and the upper wall 13d of the body portion 13a of the upper rail 13. The roller 27 has opposite side portions 27a having a larger diameter than a middle portion 27b. Both side portions 27a of the roller 27 are placed on the bottom step portions 12f of the body portion 12a.
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