Patent ID: 7516782

Claim:
A downhole tool comprising a grip assembly for contacting a well formation, the grip assembly comprising: a gripper body; a centralizer that is attached to and radially expandable with respect to the gripper body and that has a geometry which is lockable by a locking device; a force amplifier in force transmitting relation with the centralizer, wherein the force amplifier transfers a force in a first direction to a much larger force in a second direction when the centralizer is locked by the locking device; wherein the force amplifier comprises a saddle having a surface for contacting the well formation in area contact; wherein the grip assembly has a power stroke and a return stroke, and wherein the saddle remains in contact with the well formation during both the power stroke and the return stroke; and wherein the saddle has a first coefficient of friction with the well formation during the power stroke and a second coefficient of friction with the well formation during the return stroke, and wherein the first coefficient of friction is higher than the second coefficient of friction.