[GreenKeys] Model 15 Motor Speed

[Ralph Mowery]

The other gear is different.  

 

35 teeth on the 2100 rpm motor 

30 teeth on the 1800 rpm motor.

 

I am going to send a chart with the gears for most common old machines. 

 

Ralph ku4pt

 

 

From: greenkeys-bounces at mailman.qth.net [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of Ken Kinderman
Sent: Friday, January 31, 2020 5:23 PM
To: GreenKeys at mailman.qth.net
Subject: [GreenKeys] Model 15 Motor Speed

 

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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