Patent ID: 7607497

Claim:
An expandable assembly for anchoring a tool in a passage, said expandable assembly comprising a first tractor for moving a tool through a passage, said first tractor comprising: an elongate body defining a first longitudinal axis; and an expandable gripper assembly comprising: a first actuation assembly longitudinally slidable with respect to the elongate body, said first actuation assembly including a roller mechanism; a second actuation assembly longitudinally slidable with respect to the elongate body; a roller link having first and second ends, said first end being coupled to said elongate body, said roller link having an inner surface facing said elongate body and configured for engagement with said roller mechanism; a toe link having an outer surface for engaging an inner wall of the passage, said toe link having first and second ends, said first end of said toe link being pivotally coupled to said second end of said roller link at a first pivot location; and a toggle link having first and second ends, said first end of said toggle link being pivotally coupled to said second end of said toe link at a second pivot location spaced apart from said first pivot location, said second end of said toggle link being coupled to said second actuation assembly; wherein movement of said first actuation assembly causes said roller mechanism to move away from the second end of said roller link and toward said first end of said roller link so that said roller mechanism pushes said inner surface of said roller link thereby causing said roller link to pivot away from said elongate body about said first end of the roller link and wherein movement of said second actuation assembly pushes said second end of said toggle link toward said first end of said roller link; and at least one propulsion assembly configured to advance said elongate body through the passage relative to said expandable gripper assembly.