The background: My small Iowa town wanted to dispose of its old, iron, enough-momentum-to-crush-bones merry-go-round, so they put it up for auction. A relative of mine put in the only bid. Being the handy ones, my father and I got the job of disassembling it, with an eye towards eventually putting it back together again somewhere new.
Step 1: Remove planking
The wooden planking was in mixed shape. Some had been recently replaced, and some was rotting away. A Sawzall and a crowbar made quick work of it.
Step 2: Remove wood frame
The underlying boards were in remarkably good shape, considering the age of the thing. However, we weren't going to keep them. Two cuts with the Sawzall to separate them, and the square-nutted bolt through the pipe came off easily with a crescent wrench. That allowed the wooden frame to drop off. In the photo you can see the 2 "butterfly" pieces. Like most of the machine, they're good cast iron. There is another L-shaped piece that wraps around the outside of the joint and reinforces the bottom side. It has 2 knobs sticking out which helped it align the mitered wooden parts.
Whoever assembled this used the wrong size of carriage bolts, so the square heads of the bolts just spun around in the square holes in the casting. To get these old bolts off, I had to grab the round end of the carriage bolts with vice grips and use an impact wrench on the nuts.