growler/ armature check

I remember seeing them used but never knew how they worked. I just know that the armature layed in the cradle, and it growled! Is the growling sound good or bad? What determines if the armature is good or bad?

Thanks for your help.

Not all the old units were that way, but some were, and, yes, I've had a nasty shock or two from the 2 old units I have. It's not just a matter of touching the tip of the probe. When you use it for one of it's intended purposes, to check for shorts from the windings to the armature (or frame), the whole unit becomes electrified, and easy to accidently touch. (OUCH!)

Hope my memory serves me on this one, as I haven't used one since the 60's.

Lay the armature in the growlier and rotate it periodically while the growlier is running. At the same time, take a used hacksaw blade and run it lengthwise across the top of the armature.

If the sawblade "sticks" (magnetically) to the armature, the armature is shorted.

That's how I recall the procedure, anyway; if I’m wrong, hope someone corrects me.

Allan

No, you are correct. I use a large diameter light washer to feel for shorts. Most are pretty obvious, but I have had some armatures come back after rebuild where a short showed up.I wonder whether a slight short goes undetected? Also on my tester there are continuity leads to check for shorts between the commutator(copper) and the steel. You memory serves you well. I had to teach myself how to use this when I first started rebuilding a few years ago.

• Armature testing