You should never go near a piece of machinery that has a PTO running. A frayed shirt, loose clothing, or long hair can be caught or wrapped up in the PTO shaft. The rapid turning of the PTO will not give you any time for reaction. Image how twisted clothes look after being spun in the washing machine. Your clothes and body would look the same way after being caught in a PTO shaft.
Cut points are the third type of machinery hazards to be aware of.
Cut points can be found where two moving edges slide across one another, or a single edge slides across a stationary edge. Mowers, combine heads, and forage choppers are just a few kinds of machinery that have cut points. Most machinery does not have to be moving for you to be injured. The edges are very sharp so they can cut grain, grass or hay. You can be injured by falling onto the combine header, hay mower or rotary mower.