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Adam Richard Cooper built this hand-cranked model of a classic mechanical governor–which, as MachinistBlog succinctly put it “regulates the speed of steam engines by acting as a negative feedback system”–and made the dimensional drawings and build notes freely available for download at his site. I like the idea of a hand-cranked governor model, particularly, because it provides tactile feedback of the device’s purpose: You crank it faster, it gets harder to crank.

Sean Michael Ragan

I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I write for MAKE, serve as Technical Editor for MAKE magazine, and develop original DIY content for Make: Projects.



  1. Rick says:

    Actually, on a steam engine the fact that as the balls swing out it takes more energy isn’t how it governs the speed of the engine.

    When the balls fly out the lower flange lifts up. The lifting of the lower flange would control a steam valve via a set of mechanical linkages.

    1. kakungulu says:

      The steam valve control is how the governor works in steam engines. I saw a governor built for a music box that has a plastic ring limiting the weights to a certain height/speed. I guess when the rotation reaches a specific speed corresponding to the music rhythm, the friction with the ring slows it down.
      In this case, if you dare cranking up the governor to more than the max speed, the weights lift up to your face level and slap you. That’s sort of speed control…

  2. Upgrade says:

    And that, ladies and gentleman, is the origin of the expression “balls out”.

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