| 摘要 |
A device for removing irregularities in or enlarging a buried duct comprises a cylindrical housing (10) corresponding approximately in diameter to the required diameter of the duct, a plurality of tapered leaf members (14) pivotally attached at their rear ends to the front of the housing, and a conical wedge (18) driven by an axial hydraulic ram (12) mounted inside the housing (10). In operation, the apparatus is drawn through the duct with the leaf members (14) in a retracted position in which they form a tapered nose portion, until an irregularity in the duct causes resistance to forward movement. The ram (12) is operated to force the leaf members outwardly against the wall of the duct to remove the irregularity. The leaf members (14) are then retracted as the apparatus is drawn forward to the next obstruction. The apparatus is particularly intended for preparing damaged sewers prior to fitting an inner, lining pipe.
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