The Swab Cup Assembly is installed in the run-in string below the liner running tools, typically beneath the RPOB. The assembly’s seat provides a temporary seal for the liner running string, allowing hydraulic pressure to be applied for setting hydraulic liner hangers and releasing HRRT running tools.

A setting ball is circulated to the ball seat within the assembly, creating a tubing seal that enables pressure application to actuate the hydraulic liner hanger and release the HRRT running tool, if used. After the hanger is set and the running tool released, increased pressure shears the ball seat, allowing the ball to pass through and drop to the bottom. Full circulation is then restored.