|국가/구분||United States(US) Patent 등록|
|미국특허분류(USC)||404/26 ; 52/20 ; 210/165|
|발명자 / 주소|
|인용정보||피인용 횟수 : 29 인용 특허 : 1|
This disclosure is concerned with apparatus for enabling extension or other leveling adjustment of manhole cover supporting structures and the like comprising extension spacer rings resiliently compressed in self-storing fashion adjacent a support sleeve portion of the supporting structure, and adapted to be forced downward from storage to expand into position below the sleeve to extend or adjust the level of the same.
Apparatus for providing adjustable leveling of manhole covers, grates and the like within ground and similar structures, having, in combination, a tubular slip ring for supporting a cover, grate and the like near its upper edge, a base ring having a bottom flange mounting a tubular vertical sleeve positioned to receive the slip ring in coaxial telescopic relationship, and resilient spacer ring means fitted under tension coaxially against a wall of the slip ring near its lower edge and adapted, upon lifting of the slip ring along the base ring sleeve, to ...