SDS hammer drills feature a slotted drive system, meaning that the chuck is designed to fit specialist SDS drill bits. These have slots or indentations at the end of their shanks, ensuring a seamless fit into the chuck.
When in operation, the hammer action thrusts the bit forwards. Crucially, the bit’s slots also feature a pair of sprung ball bearings. These bearings are housed in the slots on the bit and act as a sort of safety mechanism, ensuring the bit stays fitted in the chuck. The indentations also help to permit the back and forth hammer action.
The hammer motion is driven by a piston, which fires the bit forward before pulling it back again in a concentrated motion. SDS hammer drills need to have a high level of strength to perform heavy-duty drilling applications, and the smooth action of the ball bearings in the bit help to boost the drill’s strength while also working to reduce friction levels.