Tunnel driving apparatus

Abstract

Tunnel driving apparatus incorporates a cutter shield with a plurality of drive members or cutters arranged side-by-side in a cylindrical array. The drive members are supported and guided for individual longitudinal displacement on a cylindrical continuous cowl or casing forming at least part of a support frame. Rams which serve to shift the drive members and the frame are coupled therebetween and extend through sealed openings in an end wall of a recess formed on the exterior of the cowl and open towards the drive members. To facilitate the creation of a concrete lining for the tunnel behind the cutter shield, a rear shield is formed by reduced rearwardly extending tails of the drive members. A further cylindrical casing locates within the rear shield and supports a pair of annular rings. One of these rings combines with a sheathing extending inside the further casing and the rear shield to form a concrete reception space. The other ring is fixed to the further casing and locates with piston and cylinder units operable to move the further casing and the rings relative to the frame of the cutter shield. To enable the interior of the cutter shield to be maintained at excess pressure, the rings engage with slidable seals on the rear shield and on the sheathing while a further slidable seal is provided between the further cowl and the casing of the cutter shield frame.

Dependencies are inferred from the claim text.