Patent ID: 7798213

Claim:
An extension/retraction apparatus for subterranean use on a tubular string comprising: a housing forming a part of the tubular string; a first member including a first connector disposed at a proximal end portion of the first member and having a rigidly mounted cantilevered detent engaging element disposed radially on an outer surface of the first connector near the proximal end of the first member; and a second member including a second connector disposed at a distal end portion of the second member and having a plurality of detents disposed on an inner surface thereof, said second member in fluid communication with said housing and relative movement between said members occurs in response to internal force or pressure provided through said housing where the element of the first connector is designed to engage the plurality of detents of the second connector in a step-wise fashion with application of pressure or force from said housing applied to at least one of said members.