Why Reach for Gasoline Brush Cutter? At the heart of a gasoline brush cutter sits a two-stroke or four-stroke engine mounted on a sturdy shaft. Fuel mixes with air inside the engine and combusts, turning a crankshaft. That rotation travels through a drive shaft to the cutting head at the far end. Depending on the chosen attachment, the head may spin a metal blade or a nylon cord that strikes plants and severs them cleanly....