Patent ID: 6427786
Filing Date: 2002-08-06
Classification: E21B

Abstract:
A tractor for moving within a borehole, comprising:an elongated body having a thrust-receiving portion, said thrust-receiving portion having a first surface configured to receive hydraulic thrust to propel said body in a first longitudinal direction, and a second surface configured to receive hydraulic thrust to propel said body in a second longitudinal direction generally opposite said first direction; a gripper longitudinally movably engaged with said body, said gripper having an actuated position in which said gripper limits relative movement between said gripper and an inner surface of said borehole, and a retracted position in which said gripper permits substantially free relative movement between said gripper and said inner surface; a fluid distribution system configured to provide hydraulic thrust to said first and second surfaces; a reverser valve having a first position in which said distribution system provides hydraulic thrust to said first surface, and a second position in which said distribution system provides hydraulic thrust to said second surface; and a motor configured to control the position of said reverser valve.