[GreenKeys] Model 15 Motor Speed

[John, W9DDD]

The most complete gear chart I've seen for 15 printer is at:
http://www.navy-radio.com/manuals/tty/1037b-5601.pdf
Page I-41 (pdf #51).  I wish it showed motor rpm.

You may notice there are a whole bunch of 7 tooth pinions with many 
different part number.

John, W9DDD

On 1/31/2020 4:54 PM, Ken Kinderman wrote:
> Thanks John. Worth checking... I have the "good" (1800 RPM) machine 
> apart for cleaning. The driven gear (fiber) has only 30 teeth, not 35 as 
> specified in the manuals as */_ Part Number 74151 with 35 teeth_/*. So 
> there's something going on there.  As to the other (2100 RPM) unit,  I 
> need to get it out of storage and pull off the monster wooden case, the 
> CH-50-A.. A real project.
> 
> Now I am really confused.. 7 teeth on the pinion, but only 30 teeth on 
> the main gear. And yet they seem to mesh OK as far as I can see. Could 
> it be that someone has messed with the motors, thinking they can 
> easily be swapped?
> 
> Ken W2EWL
> 
> On Fri, Jan 31, 2020 at 5:29 PM John, W9DDD <w9ddd at tapr.org 
> <mailto:w9ddd at tapr.org>> wrote:
> 
>     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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