Patent ID: 7954562

Claim:
A gripper assembly for anchoring a tool within a passage defining an axis and for assisting movement of said tool within said passage, said gripper assembly having a first configuration in which said gripper assembly substantially prevents movement between said gripper assembly and an inner surface of said passage, and a second configuration in which said gripper assembly permits substantially free relative movement between said gripper assembly and said inner surface of said passage, said gripper assembly comprising: an actuator; an expandable assembly comprising a plurality of links, said plurality of links including a first link secured by a first pivot and a second pivot, the expandable assembly coupled to the actuator such that the first link is selectively moveable between a retracted position and an expanded position, wherein in said expanded position, one of said first pivot and said second pivot has a position located radially outward from a position of said first pivot and said second pivot in said retracted position; an engagement assembly having a first end, a second end, and a central area, the first and second ends being pivotally coupled to an elongated shaft such that the first and second ends maintain an at least substantially constant radial position with respect to a longitudinal axis of the elongated shaft, and the central area comprising a wellbore wall gripping portion that is configured to apply force against the inner surface of said passage in the first configuration; a roller mechanism rotatably coupled to an inner surface of the central area of the engagement assembly, the roller mechanism configured to interface with an outer surface of one of the plurality of links of the expandable assembly such that the roller mechanism is advanced up the one of the plurality of links when the engagement assembly is expanded.