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NTIS 바로가기국가/구분 | United States(US) Patent 등록 |
---|---|
국제특허분류(IPC7판) |
|
출원번호 | US-0286133 (1994-08-04) |
발명자 / 주소 |
|
인용정보 | 피인용 횟수 : 22 인용 특허 : 0 |
A cover assembly for manholes and the like has a hinged cover which is urged closed by gravity and open by an opposing bias force acting between the cover and cover base in such manner as to reduce the force required to open a relatively heavy cover whose weight exceeds the maximum single person lif
A cover assembly comprising: a base having opposite ends and an access opening extending through said ends, a cover, means mounting said cover on said base for movement of said cover in opposite directions between a closed position in which said cover closes said opening and an open position and in
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