The drilling-type underreamer (DTU) is designed to run in conjunction with a drill bit or a bullnose, depending on pilot hole condition or project objectives.
Reliable deployment and retraction
The DTU's three retractable cutting arms are opened and held in position by continuous hydraulic pressure. Cutters are retracted by disengaging the pump, enabling the tool to be repositioned for selective underreaming operations or retrieval from the well. A piston spring assists with arm retraction following interruption of hydraulic pressure.