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How a flyball governor works

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  • wierdscience
    replied
    Originally posted by brian Rupnow View Post
    Okay---I take it back. Mayhap I disremembered. I thought I had seen pictures of them on steam locomotives, but perhaps I didn't.
    Blame it on the movies maybe,that Locomotive in Back to the Future III or whatever it was had a flyball governor of sorts on it.
    http://youtu.be/1AtE54HpXBM

    Locomotives didn't have governors until the diesel era.No need to automatically regulate the engine speed on a steam Loco,that was what the engineer was for.

    Very nice job on your governor BTW!

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  • Evan
    replied
    What size of file do you need hosted Brian? It should be renamed to something other than .zip. Many viri are contained in zip files. Windows Mail Live will by default not allow them to be opened. Name it XYZ.zif and it will get through the scanners with a note to rename afterword.

    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.
    That is the effect of having too much gain in the system. For instance, if the engine can rev up very quickly that is an example of high gain and will cause oscillation. In most systems the best way to prevent hunting or seeking behavior is to provide a small deadband around the control value. That is a simple matter of providing a little "slop" or "lash" in a mechanical system. Also some friction is equivalent to electronic resistance which reduces gain in a closed loop system.

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  • ckelloug
    replied
    The high ball was a railroad signaling device from the 1800's. It's also the source of the high ball glass. It was a big ball that could be slid up and down a pole. If it was high the track ahead was clear. If it wasn't high then somebody dropped the ball.
    Last edited by ckelloug; 06-05-2013, 09:39 PM. Reason: spelling

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  • brian Rupnow
    replied
    Okay---I take it back. Mayhap I disremembered. I thought I had seen pictures of them on steam locomotives, but perhaps I didn't.

    Leave a comment:


  • mklotz
    replied
    Originally posted by jdunmyer View Post
    I'm not sure I've ever seen a steam locomotive with a flyball governor. Traction engines, yes, but not RR locos.
    I was wondering the same thing. Certainly most modern locomotives didn't have ball governors. I'm no expert but I can't think of any antiques with such a device either.

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  • jdunmyer
    replied
    From what I have picked up over the years, "balls out" came from the governors
    as stated particularly from steam locomotives;
    I'm not sure I've ever seen a steam locomotive with a flyball governor. Traction engines, yes, but not RR locos.

    Brian,
    You mention in your video about FB governors being used in older petrol engines: They're used to this day in both petrol and diesel engines. Some of the very newest engines use electronic speed controls, but I'd bet that your lawnmower has a flyball governor. Unless it's a real old and/or cheapy; those use a little vane in the cooling air stream.

    Also, there's quite a bit of complexity in the spring rate vs. lever ratio, etc. Many flyball governors have 2 or 3 adjustments to make the thing more or less sensitive, in order to control speed better or prevent "hunting", which happens if you try to make them TOO sensitive.
    Last edited by jdunmyer; 06-05-2013, 08:15 PM.

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  • dp
    replied
    Originally posted by brian Rupnow View Post
    Is there any way I can post a .zip file of drawings on here without having to post a link to a web hosting sight? The free web hosting sights include so much spam and crap that a lot of peoples computer flag them as "virus' and won't allow a download.---Brian

    I think Evan has done some hosting of things like that. I do too, but for a small fee which allows me (barely) to avoid hosting adverts.

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  • dp
    replied
    A fuller description of the flyball governor (which would put one to sleep quickly) would include the phase of the response to the change of input (rpm), gain of the mechanism (springs, ball weight, ball speed relative to the driver), dynamic range, over-rides (cold start lockout), hysteresis (dead zones, backlash), and load capacity. This is typical of feedback systems in electronics such as radio automatic gain control, auto-pilots, and vehicle speed controllers. To a degree too, it applies to the vane and impeller of windmills. Even the little vane on lawn mower speed controllers behaves this way. Taken to extremes it explains how we maintain speed of our cars while driving, how we can brake to a stop without hitting the car ahead, and turn corners using real-time turn-rate feedback and muscle control to avoid going off the road. It probably also explains indirectly how we misjudge everything if texting while driving

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  • brian Rupnow
    replied
    Is there any way I can post a .zip file of drawings on here without having to post a link to a web hosting sight? The free web hosting sights include so much spam and crap that a lot of peoples computer flag them as "virus' and won't allow a download.---Brian

    Leave a comment:


  • willmac
    replied
    Governors became very sophisticated with the use of steam engines to drive textile machinery. Small variations in engine speed caused poor quality spinning and weaving or in more extreme cases breakage of threads. Owners of mills became very interested in accurate control of steam engines. Have a look at museums (e.g. www.nmes.org) for working examples of governors on large engines. Most governors on later steam engines did not control engine speed via throttle valves; they were connected to the valve gear so that the point of cut-off was controlled instead. Corliss valve gear generally works this way.

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  • dp
    replied
    Originally posted by mikeamick View Post
    Brian .. that was really neat to see that working .. thanks

    And see'in how there seem's to be some "ball" verbiage/history mixed in .. here's a little quickie ..

    In passenger train operation .. when the conductor was telling the engr to leave a station ..
    he would say .. Hi-Ball !!! Anyone want to gather a guess ?
    Balls were used in signalling in the railroading world. http://en.wikipedia.org/wiki/North_A...ilroad_signals

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  • rohart
    replied
    You start by saying the spring will govern the speed, and you end up by saying a soft spring may be too sensitive and the engine would dither. I agree with your second analysis. The speed the engine will settle at is set by whatever adjustment there is in the lever from the governor to the throttle. The negative feedback involved accomplishes the whole task with no need for any further detail other than the adjustment, and some kind of spring to produce hysteresis - or delay - in the feedback.

    On the OT side of this thread, I liked this analysis of the origins of the monkey's fate.

    http://www.phrases.org.uk/meanings/c...%20monkey.html

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  • brian Rupnow
    replied
    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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  • Mike Amick
    replied
    Brian .. that was really neat to see that working .. thanks

    And see'in how there seem's to be some "ball" verbiage/history mixed in .. here's a little quickie ..

    In passenger train operation .. when the conductor was telling the engr to leave a station ..
    he would say .. Hi-Ball !!! Anyone want to gather a guess ?

    Leave a comment:


  • lynnl
    replied
    Originally posted by brian Rupnow View Post
    Lynnl---I have no idea what you are talking about!!!---Brian
    Well, it was a pretty clever gadget anyway. ...I assumed it was one of your creations.

    Leave a comment:

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