Abstract: A tunneling machine is disclosed for boring a side drift extending from a main tunnel. The earth boring machine includes a main beam assembly for longitudinal disposition within said tunnel. A cutterhead support assembly is connected to said main beam. A cutterhead assembly including a cutterhead is mounted on said cutterhead support assembly for rotation generally about the longitudinal axis of said tunneling machine. Power means are coupled to said cutterhead assembly for rotation of the cutterhead. A first vertical gripper assembly is slidably connected to said main beam assembly and engageable with the back and the invert of said tunnel for facilitating the advance and guidance of said main beam, cutterhead support, cutterhead assembly, and cutterhead. Guiding thrust means are provided between said first vertical gripper assembly and said main beam assembly for providing a horizontal guiding force to said main beam assembly.