[ausev] GE 11.5 inch motor

[Chris Robison]

loopcat wrote:
> Hey All,
>  I took Chris R's advise and posted the motor pictures
> to Flickr.com  
> Here is the link..
> 
> http://flickr.com/photos/22369075@N07/

Awesome. As I've recently discovered while trying to take post-mortem 
photos of Farver's dearly departed (hopefully repairable?) 10.7" Kostov, 
taking color-accurate pictures of a commutator is *really* hard. I'm 
going to guess that yours is still in good shape, from what little 
texture I can see in the photos.

One thing I'm noticing -- the motor may be rated for its intended 
service at 70 volts, but by looking at the comm bars, it appears to be 
capable of handling much higher voltage without damage (of course, 
you'll need a battery pack sized to match it). Each of those comm bar 
separators gives you about 35 volts of dielectric separation, assuming 
typical construction. So from brush edge to adjacent brush edge, count 
them up and do the math. Any higher voltage than your result, and you 
risk fireballing the commutator, but below that is reliable territory. 
You may get much more horsepower out of this motor than we've been 
thinking. The only limitation will be heating, and that will be 
determined by how the motor is wound.

> 
> One thing that concerns me, looks like the armature is
> touching the winding a little. I hear a light "woosh"
> sound as I hand turn the shaft. Is this normal? Any
> advice would be welcome.
> Thanks again, John in SA..

The *whoosh* is completely normal. It's the sound of the brushes 
dragging on the commutator, which they will always do. It's one of the 
characteristics of a brushed DC motor, and the difference between DC and 
AC induction motors. On the other hand, the Siemens AC drive systems 
from MetricMind produce an intense very high-pitch whine due to their 
choice of PWM frequency for the inverter, so I guess the whoosh is nice 
in comparison.  :o)

My Warp 13 actually makes a whoosh with a squeak in the background, 
which might go away once its broken in and the brown patina has formed 
on the comm bars. Either way, I'm going to guess that my differential 
will be significantly louder.  :o)

   --chris