A Dayton 3M029 Motor

I have an old Dayton fan-duty motor on hand that I can't think of a use for. Also, I'm going half out of my mind for want of any engaging work to do. So, I'll dismantle the Dayton motor to see what I can learn of its construction. Maybe a use for it will occur to me.

Here's a view of the motor.

The motor is not very big; frame diameter is five inches. The shaft diameter is 1/2". Effective shaft length is 2 3/8", with a 1 1/2" long setscrew flat. Rotation is CCW as viewed shaft-end-on. Stator winding DC resistance is 4.3 ohms.

Here's a view of the motor's ID label.

Measured no-load speed is about 1,175 rpm. Measured no-load current is about 1.75 A. And with that data out of the way, let's get on with dismantling the unit.

Motor Out Of Mounting Cradle

Two pry-off clips come away to release the motor from its cradle.

Note the ground continuity braid that bonds^[1] the motor's frame to the cradle.

Shock-Mounts Off

The mounts' rubber portions protrude on one side. The protrusion sides of the mounts go inboard to the motor.

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Motor Dismantled -- WEDNESDAY, JANUARY 2, 2019

Three 10-32 x 4" roundhead screws with 3/8" A/F hex nuts hold the assembly together. There are no washers. The screws' head ends go at the wiring end of the motor.

At each end of the rotor, there are two axial spacers, and a thrust washer arrangement consisting of steel/felt wick/steel.

A large oil wick surrounds each sleeve bearing.

Shaded Pole Nature-Of-The-Beast Revealed

This is a 'shaded pole' motor. This Wikipedia entry gives a brief introduction to the subject of shaded pole motors. This reference item from the Wikipedia entry is more detailed and quite good.

Here's a close-up of the stator's construction that reveals the shading coils.

They're not easy to make out, but each segment of the stator^[2] has a single, heavy gauge shading winding that serves to create a phase shifted magnetic field to start the motor.

Direction of rotation is determined by the physical position of the shading coils in their segments. This motor could be reversed, but not electrically as split-phase induction motors can be. To reverse this motor, the stator would have to be flipped around 180 degrees. (And a new hole for the input wires would have to be drilled in the front end-bell.)

So there we have the architecture of the motor. And last but not least, there's a presumably self-resetting thermal protection device tucked away in the bottom of the stator.

Reversing The Motor

Just for the sheer heck of it, I may try reversing the motor.

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Reversal Works

I drilled a 3/8" hole in the front bell-end for the wiring, and assembled the motor with the stator flipped around. I've now got CW rotation, like so.

So there we have the Dayton 3M029. I still haven't thought of a use for it.

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Notes:

[1] 'Bonds' here means 'assures electrical continuity between parts that are meant to be grounded (earthed)'. For possibly more than you ever wanted to know about bonding, grounding and earthing, see this.

[2] The stator has six segments; the rotor has thirty-three segments. How that works out to give the motor its characteristic speed is beyond me.

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