Device and method for removing irregularities in or enlarging an underground duct

Apparatus for travelling through an underground duct and for enlarging the duct or removing irregularities in the wall of the duct, wherein the apparatus comprises an elongate segmented shell arranged around a longitudinal axis of the apparatus and having outwardly facing surface portions for engaging the wall of the duct, means for expanding the shell laterally with respect to the axis from a contracted configuration to an expanded configuration for forcing the wall of the duct away from the axis to enlarge a portion of the duct and for creating a void in the duct when the shell is returned to its contracted configuration, and wherein the shell further comprises a forwardly extending nose portion having an outer surface for engaging the wall of the duct ahead of the area to be driven away from the axis.

Apparatus for travelling through an underground duct and for enlarging the duct or removing irregularities in the wall of the duct, wherein the apparatus comprises an expandable segmented shell arranged around a longitudinal axis of the apparatus and having an outwardly facing surface portion for engaging the wall of the duct over a transversely and longitudinally extending area, and drive means coupled to the shell for driving said surface portion radially away from the axis thereby to move said duct wall area outwardly into the surrounding material, and wherein, in the contracted configuration of the shell, at least part of said surface portion lies within a duct penetration diameter, and in the expanded configuration of the shell, the surface portion forms part of a forwardly tapering cone.

A device for removing irregularities in or enlarging an underground duct comprising an expandable segmented shell having two sets of shell parts arranged around a longitudinal axis of the device, the two sets comprising a front set in which the shell parts are each pivotally attached by front end portions thereof to a forward pivot assembly, and a rear set in which the shell parts are each pivotally attached by front end portions thereof to rear end portions of respective shell parts of the front set, and by rear end portions thereof to a base member.

Apparatus for travelling through an underground duct and for enlarging the duct, wherein the apparatus comprises an elongate segmented shell having a central longitudinal axis and including a shell portion which is movable radially outwardly away from the axis toward the duct wall, drive means coupled to the shell portion to drive the shell portion radially outwardly from a contracted state in which the shell portion lies within a duct penetration diameter to an expanded state thereby to engage a portion of the duct wall over a circumferentially and longitudinally extending area and to drive said duct wall portion radially away from the axis to create a space into which a rear portion of the apparatus may move when moved forward in the duct.

Apparatus for travelling through an underground duct and for enlarging the duct, wherein the apparatus comprises an elongate segmented shell of generally circular cross section having a central longitudinal axis and including a shell portion which is movable radially outwardly away from the axis and which has a circumferentially and longitudinally extending surface portion for engaging a surface area of the duct wall, and an internal fluid-driven ram means coupled to the shell portion for driving the shell portion radially outwardly from a retracted state to force said duct wall portion radially outwardly into material around the duct, the shell portion being arranged such that, in its retracted state, at least a forward end of said surface portion lies within a duct penetration diameter and, in its extended state, the surface portion in a longitudinal cross-section is inclined towards the axis in the direction of travel, whereby movement of the shell portion from its retracted state to its expanded state and back to its retracted state creates a void to allow forward movement of the apparatus in the duct.