Slow-speed synchronous timing motors

Representative are low-torque synchronous motors with a multi-pole hollow cylindrical magnet (internal poles) surrounding the stator structure. An aluminum cup supports the magnet. The stator has one coil, coaxial with the shaft. At ????? so they are parallel with the shaft. They are the stator poles. One of the pair of dirtyryrty a common shading coil. The poles are rather narrow, and between the poles leading from one end of the coil are an identical set leading from the ???? end. In all, this creates a repeating sequence of four poles, unshaded alternating with shaded, that creates a circumferential traveling field to which the rotor's magnetic poles rapidly synchronize. Some stepping motors have a similar structure.