The hammering action in a hammer drill occurs when the two opposing clutch faces—one fixed and one rotating—are pressed together as the operator pushes the drill against a surface while pulling the trigger to rotate the bit and the chuck. Two factors affect the speed of a hammer drill: the pulling of the trigger, which affects the rpm; and the amount of pressure applied with the drill against the accepting surface. The greater the pressure, the greater the hammering action, which comes from the chuck faces sliding up and down against each other. The simultaneous hammering and rotating allows users to drill into masonry or concrete at the rate of 20,000 to 50,000 blows per minute, about three to four times faster than with an ordinary electric drill. This rapid pounding could yield terrific short-term productivity, but will surely take its toll on an operator’s arm and whole body over the workday.
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