Found it."The shaded pole motor is an induction motor that utilizes a short circuited coil or copper ring called a shading coil to produce the starting torque.The shading pole is wound around one end of the stator pole face.
Current flowing in the primary stator windings will produce a magnetic field which induces a voltage into the shading coil and causes a high current to flow in the shaded pole coil.The magnetic field that is developed by the shaded pole current now opposes the magnetic field that initially created it.This shaded coil field is nearly 90 electrical degrees behinde the the main magnetic field and the interaction results in rotational torque.
The direction of rotation is determined by the shading coils with the motor turning toward the shaded pole.Reversing a shaded pole motor is very difficult.It involves either disassembling the motor and reversing the the stator end to end or moving the the shading coils".Page 350 of IPTs ELECTRICAL TRAINING MANUAL by Herb Puttz
Well not exactly what is thought but close enough i guess.A compensating winding is used i universal motors to reduce armature reaction,page 351.
[This message has been edited by frank (edited 09-12-2003).]
