three sets such as 15 are recommended also additional sets such as 43 are placed at different heights so that one sail does not block wind to another the sail assembly 15 consists of a rocker arm bearing shaft 16 and a retainer cap 17 the rocker arm bearing shaft 16 protrudes perpendicular from the upper vertical shaft 8 at the appropriate height and degree upon the rocker arm bearing shaft 16 is mounted the rocker arm 44 to the rocker arm 44 are attached the safety springs 18 and 19 hence to the connecting cables 20 and 21 which in turn are connected to the positioning bars 22 and 23 above the rocker arm bearing shaft 16 at an appropriate height are mounted two sail bearing shafts 24 and 25 protruding perpendicular from the upper vertical shaft 8 and set directly opposite of one another mounted on the sail bearing shafts 24 and 25 are two sails 26 and 27 in such a way as to hinge or swing the sails 26 and 27 consist of four hinge arms 28 29 30 and 31 two sail frames 32 and 33 two balance bars 34 and 35 two positioning bars 22 and 23 and two sail sheets 36 and 37 of an appropriate material metal plastic etc the sails 26 and 27 are held in position on the sail bearing shafts 24 and 25 by use of two stops 38 and 39 and two retainer caps 40 and 41 as the wind comes against any side of the windmill 1 it causes a sail or sails such as 26 on.