Power take-off

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Image:TractorPTOplugInMay04.jpg A power take-off (PTO) is a splined driveshaft, usually on a tractor or truck that can be used to provide power to an attachment or separate machine. It is designed to be easily connected and disconnected. The power take-off allows implements to draw energy from the tractor's engine.

Safety

Image:TractorPTOshaftMay04.jpg The PTO and its associated shafts and universal joints are a common cause of accidents and injury in farming and industry. When a piece of clothing, which can be as small as a single thread, touches a spinning part it can be pulled around the part. The clothing and the person wearing it are instantaneously pulled into the shaft resulting in loss of a limb or death. Some implements do use plastic guards to try to keep a person from becoming entangled in a PTO shaft, but even with guards people need to exercise caution around PTO shafts when they are plugged into a tractor. In some countries it is illegal to operate a PTO without the shaft guard correctly fastened.

Technical

Agricultural PTOs are standardized in dimensions and speed. The original specification calls for operation at 540 revolutions per minute (RPM). A shaft that rotates at 540 rpm has 6 splines on it, and a diameter of 1 3/8". Two newer specifications, supporting higher power applications, operate at 1000 RPM and differ in shaft size. The larger shaft has 20 splines (1 3/4" diameter), while the smaller has 21 (1 3/8" diameter). All three types rotate counterclockwise when viewed from the tractor.da:Kraftudtag de:Nebenabtrieb nl:Aftakas ja:パワーテイクオフ