Abstract: Apparatus including a rotary drilling cutter and a spoil removal conduit for the digging of a deep trench, characterized in that the spoil removal conduit is gradually adjustable in length during excavation and comprises: (a) a first conduit section, arranged proximate to said rotary cutter, and comprised of associated slidingly adjustable rigid male and female telescopic tube elements; (b) a second conduit section comprising a flexible tube having two ends, said flexible tube being connected to said first conduit section by one of its ends, its other end being disposed in the vicinity of the ground at a predetermined spoil discharge point, (c) a pulley supporting said flexible tube between said two ends; (d) lifting gear for suspending said pulley; and (e) a first cable associated with said lifting gear for supporting said pulley at selected adjustable heights.

Abstract: A drilling machine for digging trenches in the ground of the type comprising at least one substantially vertical support plate (3) on which are mounted two drilling drums (2) one one each side of it for rotation about an axis (4) substantially perpendicular to the plate.The downwardly facing edge surfaces of said plate have portions (13) inclined relative to the direction perpendicular to said plate.

Abstract: The invention relates to an apparatus for cleaning, during its extraction without rotation, of a drill formed from a helical surface wound around an axial stem. It comprises a scraper blade capable of being inserted at will between two turns of the helical drill, and that it comprises a motor for causing the scraper blade to revolve around the stem substantially in synchronism with the speed of extraction of the drill.