| 摘要 |
A height adjustable manhole cover has a lower frame (1) which sits on the support flange and with an inner frame (3) movable inside the outer frame. Threaded adjusters (2) control the position of the cover (4) fitted to the inner frame. The adjusted settings are secured by lock nuts (6,7) to prevent loosening e.g. through traffic vibrations. The lower frame can be provided with holes (10) lock the cover onto the fitting.
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