[GreenKeys] Model 15 Motor Speed

[John, W9DDD]

Shooting in the dark here.  Is is possible that the gear being driven by 
the 7 tooth pinion has a different number of teeth in the two different 
15x.  Sounds crazy.  I never had the (dis)pleasure of a governed motor 15.

John, W9DDD

On 1/31/2020 4:22 PM, Ken Kinderman wrote:
> Hello all,
> 
> I am returning to the world of TTY after 60 years and boy has the world 
> changed! Learning new things every day thanks to all of you.
> 
> Having a tough time with this situation:
> 
> I have two Model 15's (TG-7's). One with a sync motor and one with a 
> governed motor.
> 
> The data plate on the sync motor says 1800 RPM... consistent with all 
> the documentation I can find. The pinion: 7 tooth.
> 
> The data plate on the governed motor says 2100 RPM, also with a 7 tooth 
> pinion. Now that's 1.1666 times faster than the 1800 RPM sync motor. One 
> might conclude that translates to a nominal 70 WPM using the same gears????
> 
> I have never had the machine with the 2100 RPM motor running.The one 
> with the sync motor at 1800 RPM worked on a local loop years ago, but 
> that doesn't prove much because it was copying its own keyboard.
> 
> To add to the confusion, the pinion on both my motors carries Part 
> Number 74912. Teletype Bulletin 144, dated February 1931 says that the 7 
> tooth pinion is Part Number 74505, which agrees with the Army's 
> TM11-352.  All have 7 teeth.
> 
> I have never ever found a tuning fork, so my only speed check method is 
> with a strobe, which I have yet to apply to both motors.
> 
> Before I go crazy and put these machines in action, is there something I 
> am missing?
> 
> Would appreciated your comments/thoughts. Free advice always welcome.
> 
> Many thanks,
> 
> Ken Kinderman
> W2EWL
> 
> 
> 
> 
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