The shaded pole motor is also called distorted field motor is the simplest, most reliable and economical of single-phase induction motors. There are several types constructively, and one of the most common forms is that of protruding poles where each pole will have a part generally 25% to 35% of the same, embraced by a shorted copper loop.
The current induced in this loop causes the flow which cuts it to suffer a delay in relation to the flow of the part not embraced by it. The result of this is similar to a rotating field that moves in the direction of the uncaged portion to the embraced portion of the pole, producing the torque that will cause the electric motor to break and achieve nominal rotation. The direction of rotation, therefore, will depend on the side where the part of the pole is located. Accordingly, the distorted field motor has a single direction of rotation and can be reversed by changing the position of the rotor shaft tip relative to the stator. There are other methods to get the rotation inversion, but much more expensive.