Actually I've had this question asked of me before and I was hoping to never see it again. But here it is once again staring me in the face. A power take-off (PTO) is a spined driveshaft, usually on a tractor or truck which 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.
Those above are made in China and don't have the ribbed shaft. They are still dangerous and don't meet safety standards. Clothing will wrap around and become entangled on a smooth shaft.
Semi-permanently mounted power take-offs can also be found on industrial and marine engines. These applications typically use a Cardan shaft and bolted joint to transmit power to a secondary implement or accessory. In the case of a marine application, such shafts may be used to power fire pumps.
In the 80's I saw several cases where farmers were injured by this turning PTO shaft but the industry got smart and developed safety shields to protect farm workers from the spinning shaft. The same was true for grain augers; and the solution there was as simple as putting a piece of pvc pipe around the shaft. That way if you grabbed the PVC it would protect your hand and arm; or clothes as the power shaft continued to spin inside of the PVC cover. The injuries caused by a turning PTO shaft were severe. Just brushing up against one with a jacket would result in entanglement. The clothing would become wrapped in the shaft and that would pull the farmer into the shaft as more clothing wrapped around the shaft. Arms and legs were torn off. Several farmers died from the injuries when no one was within shouting distance to hear their screams for help. The injuries were gruesome and mostly permanent.
The PTO shaft was used for power.
Anyone that takes the cover off of a tractor PTO is asking for trouble. I believe there is a case in Iowa finding such an act one of gross negligence. See Dairy Farm Owner Dies during Manure Pump PTO Entanglement (Case Report: 04NY010).
On February 20th, 2004 a 53-year-old dairy farm owner was fatally injured while transferring manure from an underground storage pit to a manure lagoon. At the time of the incident, the farmer was utilizing a manure pump that was connected to a John Deere 4230 tractor via a power take-off (PTO) shaft. The farmer reached across the unshielded PTO shaft in order to operate a hand crank that would turn the manure pump chute. As he did this, his clothing became entangled in the PTO shaft, wrapping the farmer's body around the shaft. A co-worker who discovered the victim immediately called 911. Emergency rescuers responded promptly. The victim was subsequently pronounced dead at the scene.
New York State Fatality Assessment and Control Evaluation (NY FACE) investigators concluded that to help prevent similar incidents from occurring in the future:
- PTO-powered equipment should not be operated unless the PTO shield is in place and in good condition;
- Power to equipment should be turned off prior to making mechanical adjustments and;
- Entire manure handling systems should be designed to facilitate operator safety.
See also, FARM MACHINERY INCIDENTS PRESENT UNIQUE PROBLEMS by Joe Macos and company.