| 摘要 |
PROBLEM TO BE SOLVED: To provide a joining device of a main body block to a cover block for a side-ditch capable of holding clearance between a main body side cover step part and a cover side under surface, being excellent in workability of hooking and removing a cover, causing no getting out of shape in use, capable of strengthening contact point holding power to external pressure impact by causing a beam effect in the diagonal direction and capable of bringing about a noise preventive effect by eliminating the occurrence of looseness. SOLUTION: Spherical head recessed parts 3 of a diagonal directional interval of a cover block 4 are arranged in both inside cover step parts 2 of a main body block 1 for a side-ditch, and small diameter spherical head projection parts 5 having a major arc slightly more than the spherical head recessed parts 3 and having the circle center in the diagonal line inside direction to the circle center of the spherical head recessed parts 3, are arranged in an under surface part of the cover block 4 corresponding to these spherical head recessed parts 3. Clearance S can be held between a main body side cover step part and a cover side under surface by eccentric contact floating joining in the diagonal line inside direction of the spherical head projection parts 5 and the spherical head recessed parts 3.
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