"Searcher7" wrote in message
...
On Dec 12, 6:17 pm, "Jim Wilkins" wrote:

Or no one actually knows. The question is like "How long will this
bearing last" without giving the load, speed, misalignment,
temperature, contamination, etc.

-How do you figure?

Long experience building prototypes, switching signals from microVolts
to 40KV, from picoAmps to 1000 Amps, both AC (locomotives) and DC (48V
telephone batteries), and a few RF diode switches. Much of it was
custom test equipment that didn't permit sloppy design.

I trained for but never practiced teletype repair. They use a voltage
high enough to blast through minor contact oxidation:
http://ed-thelen.org/Teletype-28/index.html
http://www.navy-radio.com/manuals-ttycorp.htm

Whatever you are thinking of, if you haven't seen it done you either
didn't look hard enough or it had been tried and discarded by 1930, or
disappeared into crypto machines:
http://en.wikipedia.org/wiki/Enigma_rotor_details

These switch hundreds of contacts manually:
http://www.digikey.com/product-highl...dl-series/1174
If your alignment tolerances are good enough they can be used on the
inaccessible rear of plug-in modules.

jsw