If it is anything like the Stovepipe then there is a a bush that slips onto the crankshaft with a slotted hole in it, attached to this bush is an arm with the governor weight on it. The governor rod is bent into a circle to fit around the bush and the amount of movement of this rod alters as the bush is pulled by the weight a bit like a variable throw eccentric.
Far end of rod is threaded for nuts to adjust it's position on the "L" shaped latch
You can see the two lock nuts on the rod at the top of this photo, as the weight moves the eccentric bush out further the rod will move further towards the head end of teh engine and that moves the long arm of the "L" shaped latch to the left and engages on the keep to hold the exhaust rocker open.