Patent ID: 8720566

Claim:
An apparatus comprising: a body movably arranged about a mandrel and comprising a tool connector at a bottom of the body that is adapted to connect to a bottomhole assembly, the body being movable between a retracted position, where the lower end of the mandrel is disposed within the body at or near the bottom of the body, and an expanded position, where the body has moved downwardly with respect to the mandrel such that the lower end of the mandrel is disposed within the body at an intermediate location along the body; the mandrel slidingly disposed within the body and comprising an upper end, a lower end, a passage extending between the upper and lower ends, and a tubing string connector at the upper end for connecting the mandrel to a tubing string; a first seal and a second seal each attached to the body and in sealing contact with the mandrel, thereby forming a chamber defined by the body, the mandrel, and the first and second seals; a middle seal arranged within the chamber and being attached to the mandrel and in sealing contact with the body, the middle seal dividing the chamber into an upper cell and a lower cell and defining a fluid passage that controls the flow of fluid between the upper and lower cells; and a spring disposed within the chamber and configured to maintain the body in the retracted position until a predetermined pump rate is applied to the apparatus.