| 摘要 |
The manhole covering comprises a casing, a base frame and an adjusting device. A two-part base frame has a plurality of bores, which are aligned with pockets located in the base part of the casing. In each pocket is inserted a screw nut, into which is screwed and secured the lower end of a threaded bolt extended through the assigned bore of the base frame. The base frame is adjusted in height and slope by a pair of nuts. The adjustment of a particular slope is made possible due to the shape of the bores, which widen to either end and by convexly curved washers cooperating with the bores at their ends. The screw connection of the base frame constitutes a positive connection, which prevents breaking out of the base frame even in the case of a high, eccentric force application to the manhole covering. |
