Power Take-Offs
Tailgate Safety Talk
We typically associate power take-offs (PTOs) with tractors, but they can also be part of other power units. Regardless, PTOs are fast-revolving shafts used to transfer mechanical power to auxiliary equipment or attachments (e.g., rotary cutter/bush hog, tiller, post hole digger, flail mower, boom ax, wood chipper, log splitter, etc.).
Historically, PTO shafts were the source of many serious injuries and deaths in the agricultural and public works fields. Today’s shields and other safety features have helped reduce those incidents, but they still pose a dangerous entanglement hazard, which can be mitigated with a properly-installed shield or guard. These safety features minimize the potential for the revolving shaft and operator to come into contact. Some tips for working around PTOs and drivelines:
- Before approaching the PTO shaft to perform maintenance, clear debris, connect, or disconnect it, always disengage the PTO, turn off the tractor, and remove the keys before leaving the power unit.
- Don’t perform maintenance or make adjustments until the driveline and attached machinery have stopped moving completely.
- Never step over or reach under a moving power take-off shaft or driveline, even one that is guarded.
- Make sure PTOs are shielded with an enclosing type guard.
- Do not operate any PTO attachment without a properly connected guard that prevents entry into the point of operation by hands or fingers reaching through, over, under, or around the guard. The master shield (which covers the PTO stub on the tractor on three sides) should be in the down position. The telescoping driveline guard must operate independently of the steel driveline itself and should be secured from spinning with safety chains attached to the implement.
- Before engaging the PTO and with the tractor shut off, ensure that the guard spins independently of the PTO shaft itself.
- Do not wear loose fitting clothing or dangling jewelry when working around PTOs. Shirts should be tucked in, jackets zipped, and sleeves buttoned. Boot laces, pant legs, overalls and coveralls can similarly
become wrapped up in the PTO shaft or universal joints. Tie back long hair to prevent entanglement and scalping. Keep your head and other body parts away from an operating PTO. Even short and secured hair can become entangled in a driveline. - Do not attach equipment to the PTO unless it is rated for the revolutions per minute (RPMs) of the PTO. The most common PTOs are 540 rpms, but you may also encounter 1,000 rpm machines.
- Ground personnel or observers should be required to remain a safe distance away from the equipment while in operation. No one should be allowed to ride on such attachments, regardless of whether the PTO is engaged.
- While less common, driveline separation can be another source of injury, because once a PTO shaft is no longer connected at each end and a continuous shaft, it can fly in unpredictable directions at high rates of speed.
- PTO stub connection at the power unit and the attachment gear box must be secure.
- Universal joints must be kept in phase. This is generally addressed by the one-way only connection of modern shafts, but be mindful of this whenever modifying PTO shafts or replacing universal joints.
- Ensure that the telescoping PTO shaft does not compress completely at any point of the operating range and ensure that it has several inches of overlap at its greatest operating extension.
A lesser concern, but a risk of occupational injury nonetheless, is the stress and strain of connecting and removing PTO shafts from the power units. Most connection types require pulling back on a ball bearing retaining ring while simultaneously moving the telescoping shaft forward onto the PTO stub of the power unit. Even with a well lubricated shaft and ball bearing connection, considerable friction must be overcome while the operator is typically in an offset position because of the three-point connection. At a minimum, substantial adult language may result, but strains or pulls can occur as well. Some operators have found relief with alternative mechanical connections, such as John Deere’s Quik-Knect™ or the more generic PTO Connect and PTO Link™. These are relatively new on the market, so experience with them is still limited.
The Lake Area Technical College in South Dakota demonstrated how quickly a person can be wrapped up by a spinning PTO shaft.
The Alabama Extension office is just one source of safety videos available for free and here they cover how to install and maintain the safety shield over the PTO shaft.
The Agricultural Driveline Manufacturer’s Association has a free PTO Safety Training video and other resources to help with PTO safety.
No matter your strength or reflexes, you are no match for the power of a PTO shaft spinning nine times per second or more and limbs have literally been pulled from peoples’ bodies. You can take no chances around connected PTO shafts.
Users of this tailgate talk are advised to determine the suitability of the information as it applies to local situations and work practices and its conformance with applicable laws and regulations.
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