PURPOSE: To convert a linear motion to a rotating motion without using a cylinder by pushing a piston by a drive means in the direction of a fixed shaft so as to insert a wedge projected part into a through hole until its cross section matches the hole and pushing the through hole edge of a partition of a rotating tube by the ridge line of a wedge projected part so as to rotate the rotating tube.

CONSTITUTION: The end part of a fixed shaft 9 with a regular polygon through hole 12 and a partition 17 which is provided with a regular polygon through hole 16 similar to the through hole 12 of the fixed shaft 9 at the inner wall middle part of a rotating tube 10 are provided at the opening of the rotating tube 10. Also a piston 11 on which a regular polygon wedge projected part 20 similar to the through holes 12 and 16 of the fixed shaft 9 and partition 17 is installed erectedly are formed on a disk 18. Then the top end and middle part of the projected part 20 of the piston 11 are inserted slidably into the through hole 12 and the through hole 16 of the partition 17 of the rotating tube 10, respectively, so that a ridge line is made in contact with the open edge of these through holes 12, connected to an air or solenoid driving means so as to push the piston 11 to rotate the rotating tube 10. Thus a linear motion can be converted into a rotating motion.