Patent ID: 7757787

Claim:
An expandable drilling apparatus, comprising: a main body comprising a central bore and at least one axial recess configured to receive an arm assembly operable between a retracted position and an extended position; a biasing member to urge the arm assembly into the retracted position; a drive piston configured to thrust the arm assembly into the extended position when in communication with drilling fluids in the central bore; a flow switch integral to the main body and disposed between a distal end of the drilling apparatus and the arm assembly; a selector piston translatable between an open position and a closed position, wherein the selector piston is thrust into the open position when a pressure of the drilling fluids exceeds an activation value; wherein the drilling fluids are in communication with the drive piston when the selector piston is in the open position; a selector spring configured to thrust the selector piston into the closed position when the pressure of the drilling fluids falls below a reset value.