(ET) More lift motor observations

[Christopher Zach <czach computer org>]

Got another pair of broken lift motors here at the house. Sat down and 
took them apart for a look-see.

The first one was... well, cremated is a good way to describe it. One of 
the brush wires had burned through, but before that happened the wire 
from the field coils to the bottom brush incinerated *all* of it's 
insulation.

The circuit breaker likewise was toast. Think "destroyed" here. As in 
burned away to nothing. The wire going to the back of the motor (the 
common return wire) was also burned out to the point of being a crumbly 
burned up mess.

Apparently this motor had a "hard" life.

The second one was in better shape, however it wasn't going to work. 
Apparently the brushes were "replaced" and the new ones are so long the 
springs can't keep them against the commutator. That would explain a lot.

I think this one had a more "gentle" life.

Summary: These motors are burning up due to overload. I'm not sure if 
running them at 12 volts is a better idea, or if they just need to be 
treated a bit better. They also have no grease in them, have high 
friction, and are filthy as hell. Maybe running them at 18 volts just 
causes the current to jump too high, and the wires can't take the extra 
watts being dropped. Maybe the interconnect wires are old, and as a 
result they increase in resistance and cause problems. Maybe 12 or 10 
gauge wire will hold better than the 14 gauge stuff in there now.

I'll work on them over the next few weeks.

Chris