[GreenKeys] Model 15 Motor Speed

[Ken Kinderman]

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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