# How a flyball governor works



## Brian Rupnow (Jun 5, 2013)




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## chucketn (Jun 5, 2013)

Nice video and explanation, Brian. Thanks for taking the time and effort to show that. Now, the 64 million dollar question. Are you going to show us how to make one? I'd love to add one to my Team Build 8 Gerry's Beam engine.

Chuck


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## Brian Rupnow (Jun 5, 2013)

That's an old governor that I built and fully documented with drawings about 5 years ago. I will try to hunt up the thread for you.---Brian


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## chucketn (Jun 5, 2013)

Thanks, Brian. I'm looking forward to reviewing the thread.

Chuck


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## Brian Rupnow (Jun 5, 2013)

Here is a link to the original 3 ball governor being installed on my Webster, but no drawings.
http://www.homemodelenginemachinist.com/f16/webster-i-c-redesigned-hit-miss-9461/


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## Brian Rupnow (Jun 5, 2013)

Here is the drawings of the original 2 ball governor design. 

View attachment FLYBALL GOVERNOR--2 BALLS.zip


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## Brian Rupnow (Jun 5, 2013)

and here is a link with drawings to show how I converted the 2 ball governor to a 3 ball governor.
http://www.homemodelenginemachinist.com/f31/3-ball-governor-9474/


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## vascon2196 (Jun 5, 2013)

Great video...I'm going to share this with my Kinematics students.


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## Brian Rupnow (Jun 5, 2013)

In general, what I found was that the engine controlled by this governor would be set so that the throttle (be it gasoline or steam) was set to "wide open" by default. As soon as the engine was started, it would attempt to rev up to its peak rpm range immediately. The faster the engine rotated, the faster the stempost of the flyball governor rotated, until the balls flew out from centrifugal force and caused the spring on the stempost to compress and the lever to begin to move. This lever immediately closed the throttle or steam valve and slowed the engine down to whatever constant rpm range was desired. The trick of course, was to find a spring which had the required compression characteristics to compress to a length compatible with the rpm range which you wanted the engine to constantly run at. This required some trial and error I am sure. Once the engine rpm and spring compression reached a stable point, the engine would remain at that rpm, neither rising above it nor falling below it. If a load was applied to the engine, the engine would begin to slow down, and consequently, so would the revolving balls. The spring would sense this movement in the collar and begin to decompress (lengthen) and cause the lever to pivot---Thus opening the throttle until the engine was back up to the desired rpm range. As soon as the load on the engine was removed, the engine would begin to over rev, and the flyballs would fly out under centrifugal force, thus moving the collar and tipping the lever to close the throttle or steam valve, and slow the engine back down to the desired "nominal" rpm. This all happened very smoothly. I would have thought that the action would be very "choppy", but it wasn't--- it was a very smooth and constant operation. I know that if the spring on the stempost was too sensitive, then the engine would "dither", continually trying to rev up and down trying to reach a point of equilibrium where everything remained stable.


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## jwcnc1911 (Jun 5, 2013)

Brian, you must have read my mind!

Thank you very much for this post!


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## Victorymike18 (Jun 6, 2013)

Would it be possible to fully eliminate the need for a spring on the shaft, by using heavier weights on longer arms?


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## Brian Rupnow (Jun 7, 2013)

Victorymike18 said:


> Would it be possible to fully eliminate the need for a spring on the shaft, by using heavier weights on longer arms?


The spring on the stempost is what PREVENTS the balls from flying out freely. It is the compressive characteristics of the spring that establish what the "point of balance" is where the compressive strength of the spring equals the centrifugal force making the springs fly out. This is the "setting" at which you tie the lever to the control rod on the throttle for the desired engine speed. If the engine slows down, the balls slow down, and the centrifugal force becomes less. Consequently the spring expands and forces the lever to tilt and open the throttle to speed the engine up. Conversely, if the engine speeds up beyond its "set point", the centrifugal force becomes greater and the balls fly out farther from the center, compressing the spring. This makes the lever tilt the other way and slow the engine down.


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