| 摘要 |
The invention provides a metal cover frame for an open shaft, adapted to be installed flush with a road surface and connected in a vertically adjustable manner to a concrete frame which is adapted to rest on the upper end of the shaft, the metal frame comprising through holes provided in an inwardly projecting lip of the metal frame, and collects corresponding to the through holes in the metal frame being provided in the concrete frame, the collets being adapted to receive tightening screws penetrating the through holes.
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