| 摘要 |
PURPOSE:To facilitate regulation of the level of a cover plate depending upon the level of a road surface, by a method wherein lock bolts are located upright on a spacer ring placed on the manhole oblique wall of a manhole, and nuts tightened against the ring are located between the spacer and a mouth ring to install the mounth ring device. CONSTITUTION:A spacer 1 having a proper thickness is placed on the upper part of a manhole oblique wall 8 of a manhole, and lock bolts 2 are located upright in places along the peripheral edge of the spacer ring 1. A short taper nut 3 and a tall long nut 4 are tightened on the lock bolt 2, and a mouth ring device 6 and a cover plate 7 are placed on the upper surface of the long nuts 4 through the medium of a bolt 5 with a washer. This enables facilitation of the level of the cover plate depending upon the level of a road surface only through selection of combination and the height of the taper nut 3 and the long nut 4. |
