Tunnel driving apparatus

摘要

Apparatus for use in driving tunnels or the like comprises a front drive shield composed, for example, of elongate cutter knives supported for longitudinal displacement on a frame. In order to control turning motion of the shield the shield is connected via hydraulic control rams to a rear abutment such as a follow-up ring structure. The rams are all inclined relative to the longitudinal axis of the apparatus. The rams are divided into two groups inclined in opposite directions and the rams of each group can be subjected collectively to pressure fluid to impart a corrective torque to the frame.