THE EE WAS USING A HYDRAULIC JACK TO OPEN THE SIDE BOARD OF THE VIBRATING SCREEN, TO INSTALL A DECK FRAME; WHILE UNDER HYDRAULIC PRESSURE THEY ""BANGED"" THE SIDE OF THE FRAME WITH A SLEDGE HAM MER. THE IMPACT CAUSED THE HYDRAULIC JACK TO JUMP HITTING THE PIPE HANDLE, CUTTING THE FINGER OF THE EE.