The present application discloses a grate bar for a thrust grate of a furnace. The grate bar comprises an elongated recess (43) at a first side of the grate bar. The elongated recess comprises two parallel sliding surfaces which are oriented in longitudinal direction of the grate bar. An engaging element (38) is provided at a second side of the grate bar, which is opposite to the first side. The engaging element comprises two parallel sliding surfaces which are oriented in longitudinal direction of the grate bar. The elongated recess is shaped such that a corresponding neighboring engaging element of a neighboring part is movable within the elongated recess in the longitudinal direction relative to the grate bar. The grate bar further comprises two actuating surfaces (34,35) at a bottom side of the grate bar for taking up a protrusion of a grate.