| 摘要 |
<p>The present invention provides a mole for use in replacing or preparing for replacement an existing underground pipe. The mole is adapted for insertion into and movement along the existing pipe, and has a front portion (2, 3) provided with a cutting face for engaging the internal wall of the existing pipe and arranged to cause the wall to fracture, and a rear portion (1) provided with means for clamping to the mole a new pipe or a liner for the existing pipe, so that the mole can tow the new pipe or the liner through the fractured pipe as the mole moves therethrough. A head portion (3) of the mole is tapered towards the front and has flat or scalloped sides (4, 5, 6, 7) defining therebetween integral cutting edges (8, 9, 10, 11), the angle of taper being from 2° to 10° and the number of cutting edges being from 3 to 8.</p> |
