Patent ID: 8047304

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 retracted position and an extended position; an actuation device positioned within the tubular body; and a retaining and releasing device within the tubular body sized and configured to selectively retain and release the actuation device, wherein the actuation device is retained in a first position proximate to the retaining and releasing device when a first drilling fluid flow is directed through the tubular body and wherein the actuation device is released to be displaced to a second position when a second drilling fluid flow is directed through the tubular body; and wherein the expandable reamer is configured to operate in a first operating condition when the actuation device is retained within the first position by the retaining and releasing device and to operate in a second operating condition when the actuation device is released to the second position by the retaining and releasing device, and wherein the at least one blade is in the retracted position when the reamer is operating in the first operating condition and the at least one blade is in the extended position when the reamer is operating in the second operating condition.