Tunnel boring machine with dual support members

Claim 1

A tunnel boring machine for progressively boring a tunnel while disposed therein, said machine comprising: a rotary cutterhead assembly having cutting means mounted on a forward face thereof for engaging the end wall of said tunnel; a cutterhead support assembly located generally rearwardly of said cutterhead assembly and on which said cutterhead assembly is mounted for rotation about an axis generally coincident with a longitudinal centerline of said tunnel; a pair of elongate torque transmitting support members on opposite sides of and spaced from a plane through said axis, said support members precluding a longitudinally extending main beam on said plane through said axis which main beam would transmit a substantial amount of torque, each of said support members being connected to and extending rearwardly from said cutterhead support assembly, said support members each having a torque reaction end and each having a longitudinal centerline which remains substantially straight during operation of said machine; a gripper assembly connected to said support members rearwardly of said cutterhead support assembly so that torque is transmitted from said cutterhead support assembly to said gripper assembly by said support members, said gripper assembly having radially extensible and retractable gripper elements for selectively gripping the walls of said tunnel; means associated with each of said torque reaction ends to prevent pivotal movement of its respective support member about said torque reaction end, relative to the connected assembly of said machine, in a plane substantially perpendicular to a plane generally defined by said support members; means associated with said support members permitting limited relative longitudinal movement between said cutterhead support assembly and said gripper assembly; and drive means associated with said cutterhead support assembly and said gripper assembly and operative to cause relative longitudinal movement between said cutterhead support assembly and said gripper assembly.