Patent ID: 6202758
Filing Date: 2001-03-20
Classification: E21B

Abstract:
An earth boring mechanism with a frame (18) and a slide (22) linearly movable on the frame, the slide having an apparatus for holding (52,54,56) and for rotatably driving (58) a boring rod (24), and with a forward feed drive (60,62,64,66,68,70) for moving the slide (22) parallel to a boring direction, the forward drive (60,62,64,66,68,70) having a rotationally drivable forward feed spindle (20) arranged on the frame (18), which spindle is received in a spindle nut (82) non-rotatably connected with the slide (22), the slide (22) being movable relative to the spindle nut (82) along an axial stretch of the spindle which stretch of movement is limited by stops (98,104) fixed to the slide, the slide (22) being biased by a biasing element axially toward one of said stops, and said biasing element being a helical spring (84) designed as a compression spring which surrounds the forward feed spindle (22) and works between said spindle nut (82) and one of the axial stops (98,104).