Patent ID: 6672410
Filing Date: 2004-01-06
Classification: E21B

Abstract:
A drilling machine for use with a drill string, the drilling machine comprisinga frame supported for movement over the ground, a tower mounted on the frame, a rotary head movable along the tower, the rotary head being engageable with the drill string for rotating the drill string, a pull down cable connected to the rotary head for pulling the rotary head downward relative to the tower for pushing the drill string into the ground, a pull back cable connected to the rotary head for pulling the rotary head upward relative to the tower for pulling the drill string out of the ground, the pull back cable being subject to a slack condition in response to elastic stretch of the pull down cable, and a slack take-up device connected to the pull back cable to automatically remove the slack created in the pull back cable by the elastic stretch of the pull down cable.