Improvised Armature Growler

[BCjohnny]

I occasionally have a use for an armature growler, but not sufficient to actually purchase one. Assuming that they pretty much worked on the same principle (the armature sitting in the vee of an alternating current electo-magnet) I recently employed a portable Magnaflux yoke, mounted upside down in a vice, to test a suspected faulty armature, but even when I created a deliberate short (soldered two comm. bars together) I couldn't get more than an almost imperceptible vibration on the testing blade. Certainly a lot less of a reaction than a previously used bespoke growler.

Is the Mag yoke not up to it? Any suggestions? Am I wasting my time? I did change the included angle of the adjustable yoke ends several times, but to no real avail.

Thanks in advance.



"It's not always a case of learning more, but often of forgetting less"

 

[waross]

Leave the armature in the stator. Energize the stator with AC. On integral HP DC generators and motors 120 VAC is usually good. If you are doing automotive work, a lower voltage may be better.
Connect a voltmeter to the brushes and turn the armature. Armature faults will show up as a fluctuating AC voltage at the brushes.
A good armature should show zero Volts or close to zero volts as it is either sitting still or being turned.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[BCjohnny]

Thanks, but the bulk of the armatures I test are from starter motors, and the low resistance of the field would not make this feasible.

"It's not always a case of learning more, but often of forgetting less"