| 摘要 |
A cutter or reamer device 20 has two relatively movable parts 22, 24, the latter of which has means by which it can be drawn by traction from a leading end 26 or thrust by a push rod 12, and the former of which has arms 33 which, upon relative thrust between the two relative movable parts 22, 24 can be moved from a collapsed position to a laterally extended position in which they apply a force to a pipe through which the device is being forced in order to fracture it or enlarge its diameter (if collapsed). The arms 33 are located in positions spaced circumferentially around one of the parts 22, and are pivotally connected to the device 21. Adjacent arms 33L, 33S in the circumferential array are of different length to allow parts of enlarged surface area 34L, 41S at or adjacent their free ends to lie alongside one another. In a preferred embodiment, a method of reinstating drainage pipes is also described, in which a new liner is introduced into an existing pipe behind the cutter or reamer device, which can be collapsed and withdrawn rearwardly through the newly-installed liner when reaching the end of its run. |
