SDS drills mostly operate in 3 modes:
DRILL ONLY
In this mode, the SDS drill works just like any ordinary drill; without any hammer action. The maximum speed in Drill Only Mode tends to be slower (under 1500 RPM) but with higher torque.
DRILL AND HAMMER
In this mode the drill has enhanced hammer drill action and, despite the extra performance of using Drill and Hammer Mode, an SDS drill is often quieter than using a conventional hammer drill.
HAMMER ONLY, NO ROTATION
Not all SDS drills have this mode, which is also referred to as “roto stop” but by fitting special bits to the drill, such as chisel bits, the range of tasks manageable is greatly expanded. This mode is particularly useful for light demolition and when attempting tasks such as chasing out cable runs, creating socket cuts and removing tiles and bricks.
