Several years ago working in a power sub station was a brush cutter to clean along the right a way for the power lines. Lookes simular to this picture. The flywheel was a 48" square piece of metal about 4" thick and in each corner was a spring loaded knife that would extend when the rpm was high enough. The tractor was over a 100HP with skid plates and expanded metal covered the tractor. Never saw it being used but the area it had worked was mulch where had been trees.
Next trip it was gone so never saw in operation. often wondered about the noise.
Rhino makes one about like the picture the side skirts are lighter weight metal.
ken