Rotary cylinder -- a cylinder of cylindrical metal in which the piston is guided to reciprocate in a straight line, in which the intake and exhaust pipes and air guides are fixed while the cylinder body can rotate relative to each other and act on the jigs and coiled wire devices. The rotary cylinder is mainly composed of air head, cylinder block, piston and piston rod.When the rotary cylinder works, the external force drives the cylinder block, cylinder head and the air guide to turn, while the piston and piston rod can only make reciprocating straight movement, and the air guide pipe external connection, fixed.