On Fri, 18 Jun 2010 12:21:55 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

Dave__67 fired this volley in news:ba0b6aec-e956-
:


Ideally, aren't there constant-torque AC motors that can be stalled
indefinitely?

yep... So called "impedance protected" motors. I've been looking for one
that would produce about 20ft-lb torque at around 5 rpm.


Bodine calls them "torque motors," but they suffer the same size
shortcoming as mag particle brakes. A 20 ft-lb torque motor would be
enormous. When I was a kid I had a pair of torque motors I scavenged
from a Univac 2 tape drive. They were about the size of a cast iron
1/3 HP induction motor and could be stalled by grabbing the shaft.

http://www.bodine-electric.com/Asp/P....asp?Context=7

--
Ned Simmons