Patent ID: 7185716
Filing Date: 2007-03-06
Classification: E21B

Abstract:
1. A tractor for moving within a passage, comprising: an elongate tractor body; one or more gripper assemblies, comprising a first gripper assembly having an actuated position in which the first gripper assembly is in contact with an inner surface of the passage and a retracted position, the first gripper assembly comprising: at least one gripper defining a gripping surface, said gripper having a first end and a second end, said at least one gripper supported by the tractor body, wherein the at least one gripper defines an elongate beam having a length extending between the first end of the gripper and the second end of the gripper and said at least one gripper bows outward in said actuated position; and an actuator operatively coupled to the gripper, the actuator movable between a first position in which the first gripper assembly is in the actuated position and a second position in which the first gripper assembly is in the retracted position, where in normal operation said one or more gripper assemblies exert sufficient force on the inner surface of the passage to permit the tractor to move itself longitudinally relative the inner surface of the passage.