" Ball to the Walls"
Another origin: In aviation, the throttles (or power levers) are usually sticks with ball shaped ends. When a pilot wants full power, he moves the throttle forward towards the front wall of the cockpit. Thus, "balls to the walls" meant "full power". And in automobiles....its "pedal to the Metal".
Look at this example from a Sawmill....
http://farm3.static.flickr.com/2428/3664610901_b3fb2a0f5e.jpg
Also it should be noted that with a "Fly Ball Governor" of which you speak, there are linkage arms connected to the Ball pivot points. The idea isn't to get the balls slung as high as possible...but as the balls do rise higher with increase in RPM the linkage controls a valve that regulates the "power source" and reduces the power back to the desired RPM....thus "governing the RPM". Todays vehicles usually have an electronic speed limiter that governs the top speed to about 95-98 mph.(thank God for 60's muscle cars). The Fly Ball design has been used to control steam, fuel, and or ignition on stationary engines of all sorts.
DFX is correct in that Constant Speed Propellers us a similar technology except there are no "balls"...but are counter weighted (as he shows) to shove the prop into High Pitch if the engine looses power and a pressure over ride to feather them if necessary. Good comparison.
I have better than a dozen stationary engines that have fly ball governor weights and some are as small as a pecan...in mass. I was also noticing from your pictures that the arm extending out from the ball appears to have a purposeful offset to allow the balls to hang or maybe float. I wonder of you lubed it up it might come free and actually pivot.....just thinkin'
Also....if a governor or control valve sticks...and an engine runs away in rpm,
it can reach a point were things start to self destruct...and if those balls came loose...they could indeed become deadly projectiles. So your original comment of "small bomb"....might be more correct than you think. Its happened.
Mojjax..... Very cool illustration website. I'll save that one, thanks.
I think its Tony for the Win.
TiredIron