Abstract: The connection between a residential junction pipe or the like and a sewer pipe is repaired by a cutter head that is led into the junction pipe and operates essentially with its front face. Thereby, it is unnecessary to locate junction pipes in a replaced sewer pipe as is the case with known methods. The cutter head is fastened at the front end of a flexible shaft. A feeding device feeds the cutter head during cutting. A fastening mechanism centers the device in the pipe to be worked. The cutter head includes an eccentric head rotatable about the center axis of the pipe and a cutter wheel that is rotatably supported in the eccentric head that moves in a circular orbit in the pipe. The fastening mechanism includes three radially adjustable supporting elements and a hydraulic piston-cylinder unit pressing the supporting elements against an inner wall of the pipe. After fastening of the supporting elements, the cutter head is moved by the feeding device in the pipe to achieve cutting.

Abstract: A sewer pipe to be replaced is worked, starting from a manhole, by a cutter head which is braced at a front end of a new pipe to be force in from the manhole. The cutter head is guided in the pipe to be worked during the cutting operation. Such guidance is accomplished by a guide mechanism, which is mounted on the front on the new pipe and which is pressed with adjustable pressure against the inner wall of the old pipe and is slid therein. The cutter head is prevented from shifting sideways and enables that even reinforced pipes can be worked. The new pipe can be laid on the same level owing to an eccentric adjustability of the cutter head relative to the old pipe, despite any eventual change in diameter.