Foremost Dual Rotary drills feature two rotary drives, including a unique lower rotary drive that is used to advance steel casing through unconsolidated overburden such as sand, gravel, glacial till and boulders. The lower drive feeds and rotates the casing independently of the top drive.
The casing is held securely in the lower drive by a set of power-operated jaws. A carbide-studded casing shoe, welded to the casing bottom, cuts through the overburden. Once the desired casing depth is reached, the DR continues drilling open-hole like a conventional top drive drill. There is no need to trip out or change tools when transitioning to open-hole drilling.