Reversing a shaded pole motor

This article and videos contributed by Ron Walters

Shaded pole motors come in a variety of shapes and sizes and are convenient for powering displays, models and marble machines. Sometimes these motors are running in the opposite direction to what we would prefer. Most of them are constructed so we can reverse the rotation by reversing the field. It is fairly easy to take these apart to turn over the stator which reverses the field so the motor will run in the opposite direction.

It's easy to determine the direction of rotation of a shaded pole motor. The rotor will always turn from the middle of the pole towards the "shaded" portion of the pole. The shaded part of the pole is with the small exposed copper windings.

This motor will run clockwise, seen from this side.

To reverse the motor, start by removing the bearing holder...

...and then the rotor.

taking note of the location of any spacers and shim washers so you can reassemble the parts in exactly the same positions.

The stator contains the shading poles. The position of shading poles determines the direction of rotation of the rotor. We want to flip over the stator so the shading poles end up on the opposite side.

Sometimes the laminated plates of the stator may be slightly misaligned.

Supporting the stator in a vise and gently tapping the plates into position with a pin punch can easily correct this.

Reassemble the motor so the shaded poles end up in the desired position.

The shading poles get very hot. The rotors of some shaded pole motors have a long shaft intended for a small fan blade to cool the shading poles.

The rotor of the shaded pole motors has very little torque (especially when first started) and these motors generally contain a gearbox.

The gearbox contains grease. The rotor in this particular motor turns 3500 RPM.

The gearbox provides a 183:1 reduction for an output speed of 19 RPM with a considerable amount of torque.

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