weird DC motor

Date: Fri, 09 Nov 2001 19:34:17 -0000
From: stevesng@...
Subject: Re: weird DC motor

--- In CAD_CAM_EDM_DRO@y..., "Dale Smith" <mediasmith@m...> wrote:
> OK guys!
>
> Photos are at http://home.mmcable.com/mediasmith/
>
> Many servo setups have a motor and tach on a common shaft
> with two separate sets of everything including brushes, but
> the tach brushes and wiring are typically much smaller.
>
> +++Everything appears to be equal and the exit points of the wires
>indicate the brushes may be 45 or 90 degrees offset from each other.
>

OK, looks like a servo motor to me. The current rating could
be explained by the "continious duty". Servos will have a
much higher "peak" power and current drain, and that may
not have been put on the name plate. This also would be
consistent with the fan port on the motors. Servos often
have to put out a lot of power while not actually turning
very fast, making a conventional shaft mounted fan useless.

<snip>
>
> +++ Grab a tight hold! The resistance is about the same.
>One set of brushes reads from 0.4 to 0.7 ohms. the other set
>reads from 0.6 to 1.0 ohms
This mystery seems mostly solved. We are left with wondering
why they used two commutators instead of the more usual
arrangement of multiple brush pairs on one commutator.


xxxxWell, we do have part of the mystery left. What does a fat boy do with DC servo motors that weigh almost as much as he does? The original plan was to drive lathe, mill, and drill press with them. I only learned Washington and DC motor weren't related a few weeks ago and through this list, learned that a stepper had nothing to do with dancing. I can't even spell SirVooh yet. :o)

And now, today's guesses:

1. Could the 2 commutators allow higher power/higher voltaage? 110-G-110 or 220@ .4A + 220@ .4A = 220@.8A?

2. Since they appear to run on plain old DC, what about just using them as DC motors as intended (with forced air and current limits) ??

I would get one of those Gecko drives but I'm afraid it would run up the wall with me.

Thanks guys!

wdsmith



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