[GreenKeys] Western Union

[Bruce Gentry]

Starting torque would probably have been the main problem. Synchronous 
motors can develope excellent torque once up to speed. The motors used 
in Teletype equipment have a hard steel rim on the rotor instead of a 
squirrel cage winding. That reduces starting torque but is crucial to 
synchronous operation because it becomes strongly magnetized to lock in 
to line frequency. Regarding power, decades ago not all power stations 
were connected to the grid and produced power at a nominal frequency. 
The main concern was to give the same number of cycles each hour or day 
so clocks would be accurate. The coming of television changed all of 
that. Poorly designed or maintained receivers could be affected by line 
frequency and would have unstable vertical sync or dark bars rolling 
through the picture. Customer complaints caused utilities to govern 
their frequency closely.

     Bruce Gentry, KA2IVY


On 4/25/19 10:44 AM, Jim Haynes wrote:
> On Thu, 25 Apr 2019, Peter Gottlieb wrote:
>
>> Interesting, I assume they couldn?t count on line frequency and 
>> synchronous motors for speed control.
>>
>>
> Certainly not in an airplane.  And I guess not in other places either.
>
> I found a document where Teletype R&D had been asked about putting in
> a sync motor.  On the first attempt they couldn't find a sync motor
> small enough to fit into the space that had enough torque to run the
> machine.  I don't know if there ever was a sync motor worked out for it.
>
>
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