Backreamer for a tunneling apparatus

Abstract

A backreamer includes a distal end configured for connection to product and a proximal end configured for attachment to a distal end of a drill string. The backreamer includes a backreaming cutter having a cutting side that faces toward the proximal end of the backreamer. The backreamer also includes a proximal assembly that extends between the proximal end of the backreamer and the backreaming cutter. The proximal assembly defines a vacuum passage for removing material cut by the backreaming cutter. The backreamer further includes a drive stem for transferring torque to the backreaming cutter for rotating the backreaming cutter. The drive stem is rotatably supported within the proximal assembly such that the drive stem and the backreaming cutter are rotatable relative to the proximal assembly. The backreamer additionally includes a distal assembly that extends between the backreaming cutter and the distal end of the backreamer. The distal assembly includes a vacuum blocking plate positioned distally with respect to the backreaming cutter. The backreaming cutter and the drive stem are rotatable relative to the vacuum blocking plate.