Abstract: An apparatus for converting centrifugal energy into percussive energy is operated by a motor continuously rotating a driven shaft whereby a rocking shaft is caused to oscillate about a pivot axis under the influence of the centrifugal force produced by a weight body during rotation of the driven shaft. The rocking shaft has a slot at its pivot axis and a bar extends through the slot and radially beyond opposite sides of the rocking shaft. Upon the rocking shaft oscillating in opposite directions, the opposite ends of the bar are deflected in opposite directions, so that one end of the bar urges a spring biased striker away from an anvil when the shaft rocks clockwise while the other end of the bar acts on the striker in a similar manner when the shaft rocks counter-clockwise.