Flyball governor

Interactions

click the loom, the grindstone or the hoist: its belt is shifted onto the fast pulley (or off); the engine sags, the balls drop, the throttle opens and the speed recovers to a little below the mark
drag the brass pin along the slotted lever: more or less gain in the loop; past the stability boundary the engine hunts, and the engine man later slides the pin back
click the dashpot: its drain cock empties the oil and the governor hunts; click again (or wait) and the engine man refills it from his oil can
drag a governor ball outward and let go: the collar lifts, the throttle shuts, the engine slows, then recovers
click the fire door: it swings open and the engine man shovels coal in; the boiler pressure climbs, sometimes enough to lift the safety valve