When parts of a machine continue to move after the power to the machine has been turned off, they are called freewheeling parts. To avoid injury from freewheeling parts, stop the tractor engine, disengage the PTO, and wait for the machine to stop completely before doing repairs or adjustments.
This video is used for the National Safe Tractor and Machinery Operation Program (NSTMOP), www.NSTMOP.psu.edu, and in the AgSafety4U program.
More Agricultural safety videos can be found on eXtension's AgSafety4u Youtube channel: https://www.youtube.com/user/AgSafety4u/videos