[GreenKeys] Teletype 50HZ and 60Hz motors

[E. Groenenberg]

On Wed, June 26, 2019 08:30, Jerry Murphy wrote:
>
>
>
> The motor which is most often found in M28 and M35 machines is the LMU3.
> The LMU3 runs on 120VAC and 60HZ current.  It turns at 3600RPM and puts
> out 1/20th HP.  Its 50HZ cousin is the LMU38.  It runs on 120VAC and
> turns at 3000RPM and puts out 1/20th HP.  The ONLY difference between
> the LMU3 and the LMU38 is the thermostatic protection switch.  The LMU3
> consumes 1.85 amps when running while the LMU38 consumes 2.4 amps.  If
> you wanted to run an LMU3 on 50HZ current, you might want to short out
> the thermostatic protection switch and put a time-delay fuse in the motor
> power leads.  The capacitor, starting relay, rotor and stator are the same
> on both motors.  Find more information on M28 and M35 motors here:
>
> http://navy-radio.com/manuals/tty/jh/bsps/bsp/570series/570-220-100TC-Iss4.pdf
>
> The 1/12th HP motor that is found on M28 ASR sets is the LMU12.  It turns
> at 3600RPM when fed with 120VAC of 60Hz current.  It should NOT be used
> on 50Hz current.  Teletype made a special motor for powering M28 ASR sets
> on 50Hz current.  The motor is the LMU50.  A quick look will reveal that
> the LMU50 is about 1.25 inches longer than the LMU12.  The rotor and
> stator
> are bigger and contain more iron.  The capacitor and starting relay are
> also different from the LMU12.  There is an ebay seller who has an LMU50
> for sale at this time.  Here is the link:
>
>     www.ebay.com/itm/254172915159
>
> The seller does not refer to it as an LMU50 but that is what it is.
>
> Go to the M28 motor parts manual and look at the 304538 motor mounting
> cradle to get an ideal of how much longer the LMU50 motor is.  Here is
> the link:
>
>     http://navy-radio.com/manuals/tty/570-220-800TC-6701.pdf
>
> Teletype did make a 1/20th HP motor for use on 50Hz current and 230VAC.
> that motor was the LMU55.  Of course, it would also work on 60Hz current
> at 230VAC.
>
> Regarding the unusual device that is attached to the motor fan on Ed
> Groenenberg's M35 KSR, it appears to be a centrifugal device that
> operates a switch to let some device know that the Teletype machine is
> running.  There are several of these switches shown in the Teletype
> motor parts list.  Look on pages 24 and 26 of the motor parts manual.
> Here is the link:
>
>   http://navy-radio.com/manuals/tty/570-220-800TC-6701.pdf
>
> Jerry Murphy
>


Jerry & others, thank you for the excellent description, it was very useful
for me.

I did test my latest M35 and it just needs a little bit of lubrication here
and there, but is otherwise in fairly good shape.
It's is also a tractorfeed version and I taught that some of the tractor
pins were broken off. But the are actually getting pulled inwards as the
platen moves, a very clever solution.

As both my KSR35's are originally 115V/60Hz based usnits, and that I am
receiving a 115V/60Hz based ASR32 very soon, my next step is to acquire a
12V/60Hz inverter (1KW version and pure sine) so I could setup a few wall
sockets for 115/60Hz equipment.

Ed
--
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