Even with a relatively quick reaction time of five-tenths of a second, the wrapping action has begun. Once wrapping begins, the person instinctively tries to pull away. This action simply results in a tighter, more binding wrap. The 1,000 rpm shaft roughly cuts in half th opportunity for evasive action. PTO powered machinery may be engaged while no one is on the tractor for many reasons.
Examples are elevators, grain augers, and silage blowers.
At other times, adjustments or malfunctions of machine components can only be made or found while the machine is operating. Additionally, many work practices such as clearing crop plugs leads to operator exposure to ope ating PTO shafts. Other unsafe practices include mounting, dismounting, reaching for control levers from the rear of the tractor, and stepping across the shaft instead of walking around the machinery. An extra rider while PTO powered machinery is operating is another exposure situation. The wrapping hazard is not the only hazard associated with IID shafts.