[GreenKeys] Model 19 Gear Set

[w9ddd at tapr.org]

Apparently they didn't do that for 28 gear motors which run at 3,600.  

 I tried to forget everything they taught in the motors course.  (Friend and I were grumbling about the text book for the course on 6m.  Turned out that one of the authors monitored the same frequency.  Beware of EE professors with tickets.)

Anyhow I'd guess it has something to do with torque vs rpm curve.  Or perhaps the speed was chosen back before 60 Hz power was commonly available.  Therefore easy gear ratios favored 2,100.  

Wouldn't it be fun to have access to engineer's notebooks of the era?

John, W9DDD


> On Apr 18, 2020, at 6:00 PM, Jim Haynes <jhhaynes at earthlink.net> wrote:
> 
>> On Sat, 18 Apr 2020, John, W9DDD wrote:
>> 
>> TM11-352 on page 22 lists these as a 7 tooth pinion and a 35 tooth gear.  If we do the math using an 1,800 rpm motor, we get 360, a little slow for a receive or transmit shaft.  If we assume a 2100 rpm governed motor, then we get 420 RPM for the receive shaft.  Which is the normal receive shaft speed for 45.45 baud.
> 
> Yes, it certainly is a mystery why they chose to run the synchronous and
> governed motors at different speeds.