Power Take-Offs: Useful, but Potentially Dangerous

To anyone unfamiliar with modern agriculture, it might seem strange to see farms compared to industrial spaces. However, a farm or ranch can be as hazardous for workers as any shop floor. According to the National Institute of Occupational Safety and Health (NIOSH), farmers and farm workers are at increased risk for on-the-job injuries and deaths due to falls, exposure to toxic substances, and heavy machinery accidents.

One common source of machine injury is the power take-off (PTO).

What is a PTO?

A power take-off is a mechanical connection point, usually on a tractor, combine, or truck, that can be used to drive a variety of farming machines or implements such as hay bailers, pumps, woodchippers, or manure spreaders. The connection is generally made by coupling a PTO’s output crankshaft with an implement’s drive shaft.

What makes a PTO dangerous?

When a PTO is connected to an implement’s drive shaft [also referred to as the implement input driveline (IID)], it causes the shaft to rotate at a very high rate, increasing the likelihood of a severe or fatal injury if things go wrong. Most injuries stemming from encounters with a PTO involve entanglement of hair, clothing, shoelaces, or even just thread from a garment in the spinning shaft. Once this entanglement happens, both the clothing and the wearer can quickly get wrapped around the shaft, leading to catastrophic injury including severe contusion, cuts, spinal and neck injuries, dislocations, broken bones, and scalping.

Another source of danger in using a PTO occurs when the implement is attached to the PTO improperly. The implement’s drive shaft is typically housed in a telescoping casing, with one part of the shaft sliding into another, making it easier to hitch the implement to the PTO, and ensuring that the coupling works even when the implement is turning or on uneven ground. If the IID isn’t attached properly, the implement and the drive engine can separate, and the drive shaft can strike anyone standing too close, or even sheer off, becoming a deadly projectile.

Use the Shields

Make sure you and everyone who works around your PTO know the rules of operation. It might be tempting to save time (for instance) by connecting and disconnecting equipment from the PTO by disassembling the fences and other safeguards your unit is equipped with, but these should remain in place during operation.

Master shield: This is essentially a fence that covers the PTO, extending over it on three sides. It prevents direct contact with the PTO stub and drive shaft when the engine is running. Before operating PTO-powered machinery, make sure that the master shield for the PTO stub and front joint is secured properly. Replace damaged master shields.

Driveline shield: A bell-shaped cover for the universal joint on the implement’s shaft. Made of plastic or metal and equipped with bearings, the driveline shield rotates with the shaft but stops spinning when a person touches it. As part of the pre-operation inspection, make sure that the driveline shield rotates freely on its bearings, and if it is equipped with a tether, ensure that the tether is attached and in good condition.

More Safety Tips

In addition to having shields in place, here are some PTO safety guidelines provided by the Agricultural Safety and Health eXtension Community of Practice (CoP), a collaborative effort between universities, industry, and government.

• Never step over a rotating shaft.
• Do not wear loose-fitting clothing around PTO-driven equipment.
• Tie back long hair or secure it under a hat before operating equipment.
• Ensure that safety decals, such as “Rotating Driveline: Contact can cause death,” are readily visible. Replace decals that are obscured or incomplete.
• Always disengage the PTO and shut off the engine before dismounting the vehicle.
• Never work on machinery or equipment while the engine is running or is energized.
• Keep universal joints in phase.
• Do not switch drivelines between machines.
• To reduce driveline stress and separation, position the tractor’s drawbar appropriately for each piece of machinery.
• Reduce PTO shaft abuse by avoiding tight turns, reducing excessive telescoping, engaging power to the shaft gradually, and avoiding over-tightening the slip clutch on PTO-driven machines.
• Examine the driveline for protruding pins or bolts and debris such as mud that has dried onto the driveline shield. Clothing snags easily on such protrusions, resulting in entanglement incidents.

Sources: ag-safety.extension.org; wptpower.com

The information included here was obtained from sources believed to be reliable, however Grinnell Mutual Reinsurance Company, SI, and its employees make no guarantee of results and assume no liability in connection with any training, materials, suggestions, or information provided. It is the user’s responsibility to confirm compliance with any applicable local, state, or federal regulations. Information obtained from or via Grinnell Mutual Reinsurance Company, SI, should not be used as the basis for legal advice and should be confirmed with alternative sources.

1/2026