Patent ID: 8196679

Claim:
An expandable reamer apparatus for subterranean drilling, comprising: a tubular body having a longitudinal axis and a drilling fluid flow path therethrough; at least one blade carried by the tubular body and movable between a first position relative to the tubular body and a second position relative to the tubular body different from the first position, the at least one blade being configured to repeatably move between the first position and the second position responsive to fluctuations in drilling fluid flow through the tubular body when the expandable reamer apparatus is in a first operational state, the at least one blade configured to be retained in one of the first position and the second position during fluctuations in drilling fluid flow through the tubular body when the expandable reamer apparatus is in a second operational state; an actuation device; and a retaining and releasing device within the tubular body sized and configured to selectively retain and release the actuation device, the expandable reamer apparatus being in one of the first operational state and the second operational state when the actuation device is retained within the retaining and releasing device and being in the other of the first operational state and the second operational state when the actuation device is released from the retaining and releasing device.