Topband: Yikes! Heavy snow, freezing fog and 23 degrees F in Raleigh, NC

[Charlie Cunningham]

Thanks, Tom!  That all makes sense! Come to think of it, the Briggs &
Stratton engine on my 5500 watt generator maintains its speed well. I don't
know what sort of feedback it uses, but it's effective! If I make a big load
change, like bringing on a water heater, I can hear a "pitch" change but the
speed remains constant. In the old days I've seen trucks and tractors used
to run saws for cutting timber. I guess that sort of give awa y  how old I
am and what a "hillbilly" I am!  :-)

Take care down there!

73,
Charlie, K4OTV

-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Tom W8JI
Sent: Wednesday, February 12, 2014 8:29 PM
To: Charlie Cunningham; 'topband List'
Subject: Re: Topband: Yikes! Heavy snow, freezing fog and 23 degrees F in
Raleigh, NC

> Gee, that should work great, Tom! How is the shaft rotatoion speed
> controlled to maintain 60 Hz?
>

Tractors are like almost any other thing that has an engine and a manual 
throttle control, including lawn mowers. They have engine speed feedback 
that works like "mechanical ALC".  It isn't like car or something that has 
an open loop system with a human stuck there pushing a pedal to regulate 
power with varying loads. If it didn't have that feedback system, a person 
would have to constantly adjust the throttle when mowing or plowing. I guess

you could think of it like a cruise control, except unlike cruise it is the 
primary throttle and has wide dynamic range. Lawnmowers regulate the 
carburetor throttle plate with a connection to a flapper plate. Air from a 
finned wheel hits that plate. The plate works against a spring, and the 
throttle just changes spring tension. The tractors around here are a little 
more sophisticated, but same basic concept. They stay put pretty good. 
Within a Hz or so at the most. 

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