Patent ID: 7351011

Claim:
An apparatus for defining a passageway through a composition between first and second locations, the apparatus comprising: a cable pulling assembly; and a support for the cable pulling assembly, the cable pulling assembly comprising a capstan assembly, with a part of the capstan assembly guided in movement around a first axis and engagable with a cable connected to a mole so as to cause a cable engaged by the part of the capstan assembly to be pulled as the part of the capstan assembly is driven around the first axis, the part of the capstan assembly comprising a circumferential groove, bounded by a surface and extending around the first axis, for reception of a cable to be pulled, the groove configured so that a circumferentially localized force is applied by the groove surface to a cable operatively positioned in the groove tending to avoid circumferential slippage between the part of the capstan assembly and a cable operatively positioned in the groove.