[time-nuts] Odd request

[Normand Martel]

Hi Tom...

Not only Telechron were very popular electric clock
movements, they were BY FAR  the very best mechanical
movements ever made.

When young, i've opened A LOT of used
electro-mechanical clock movements, and most of them
showed evident traces of wear. Worn-out gear pinions,
dried-out and seized brass/steel bushings, dried-out
and cracked nylon pinions (Nylon tends to harden and
shrink with time and heat, so Nylon parts shall NEVER
be put on a traction stress when manufactured) were
frequent on old clock movements, but NEVER on
Telechrons, except very
rare cases of pinion wear on the output shaft (3.6
RPM)

Telechron movements were very unique. The motors were
two-pole shaded pole synchronous motors with an
external solenoid and a completly sealed rotor
stuck within the poles pieces. The self-starting
rotor, composed of three spring steel disks forced in
place on a smooth shaft and spinning at 3600 RPM (60
Hz) was inside a sealed cylindrical aluminum gearbox
(older gearboxes were in a copper sealed box)
containing not only the rotor shaft, but also a 1000:1
reduction geartrain. Pinions were made of stacked thin
steel pinion disks forced on the shaft to form single
solid pinions. The faster rotating gears plates were
made of some kind of red-orange colored fiber material
and the slower rotating (higher torque) plates, of
soft brass. The gear holding plates were made of thick
alunimum with a thinner aluminum subplate that
prevented the gears from sliding longitudinally, but
far more important, the thin space between the plates
and subplates had a capital role: Keeping a fine
capillary oil film between the plate and subplate,
that film kept the gear shafts permanently lubricated,
thus eliminating all trace of wear. Even the gears
themselves (the rotor was spinning at 3600 RPM and the
second gear, at 864 RPM) didn't show any trace of
wear, even under a magnifying glass.

I even remember the gear ratios of a Telechron:

Rotor: 12 toothed pinion (3600 RPM)
Second gear: 50 tooth fiber plate coupled to a 12
tooth pinion R:r: 4.1666667:1
 Third gear: 54 tooth fiber plate coupled to a 18
tooth pinion R:r: 4.5:1
Fourth gear: 60 tooth fiber plate coupled to a 12
tooth pinion R:r: 3.3333333:1
 Fifth gear: 60 tooth brass plate coupled to a 12
tooth pinion R:r: 4:1
Output gear: 60 tooth brass plate coupled to an
external 10 tooth pinion R:r: 4:1

4.16667*4.5*3.333333*4*4=1000

Definitely a fine movement! I still use an oooold
Telechron at my shop.

73 de Normand VE2UM

--- "Tom Van Baak (mobile)" <tvb at LeapSecond.com>
wrote:

> 
> See Mitchell's SWCC page at:
> http://www.telechron.com/
> 
> /tvb
> 
> 
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