A timing apparatus for sickle knives having adjacent knife ends, respectively, having an endless elongate element encircling and movable about spaced apart support elements such that first and second portions of the elongate element span a space between the support elements, and connector elements connecting the knife ends to the first and second portions of the elongate element, respectively, such that movement of the elongate element in a first direction about the support elements will move the knives in timed relation in first opposite cutting directions, and movement of the elongate element in a second direction opposite the first direction will move the knives in timed relation in second opposite cutting directions. The apparatus can be connected between separately drive knives for timing their motions, or for using one of the knives for timingly driving another of the knives.