PERCUSSION PISTON

摘要

A percussion piston (1) for a rock drill (2) comprises: a pilot cylinder (3); a distributor (4); a pressure medium; and a control edge (5) which changes the position of the percussion piston (1) in the position of the distributor (4) in a direction parallel with the shaft direction of the percussion piston (1) when the percussion piston moves in an impact direction (A) in regard to the pilot cylinder, wherein the control edge (5) comprises: one or more notches (6) which are formed in the outer surroundings (7) of the control edge, and are arranged to cause the starting of the state change of the distributor (4) before the control edge of the percussion piston passes through the corresponding control edge (8) provided in either the distributor or the pilot cylinder.