Abstract: A tunneling shield for shielding the area of a tunnel between first and second tunnel machine assemblies which are longitudinally, relative to the axis of the tunnel, movable relative to each other comprising a plurality of extendable and retractable support beams, the longitudinal axes of which are substantially parallel with the axis of the tunnel. The support beams may be disposed near the wall of the tunnel at circumferentially spaced intervals from each other an connected at each end to a first and second tunnel machine assembly by flexible joints. Each of the support beams may comprise first and second telescopically engagable members to effect extension and retraction of the support beams in response to relative movement between the first and second machine assemblies.

Abstract: A tunnel boring machine comprising a rotary cutterhead assembly, a cutterhead support assembly on which the cutterhead assembly is mounted, a gripper assembly for gripping the wall of the tunnel, and a pair of elongate support members connecting the cutterhead support assembly and the gripper assembly. The support members each have a torque reaction end connected either to the gripper assembly or to the cutterhead support assembly. Apparatus associated with the torque reaction ends prevents pivotal movement thereabout of the support members in the plane perpendicular to the plane in which the support members lie.