A power take-off (PTO) shaft transfers mechanical power from a tractor to an implement. While some PTO-driven equipment is operated from the tractor seat, other types of farm equipment, such as elevators, grain augers, silage blowers, and so on, are operated in a stationary position, letting the operator leave the tractor and move around in the vicinity of the implement.
A PTO shaft rotates at a speed of either 540 rpm (9 rotations per second) or 1,000 rpm (16.6 rotations per second). At these high rates of speed, a person's limb can be pulled into and wrapped around a PTO stub or driveline shaft several times before the person can react. The fast rotational speed, operator error, and lack of proper guarding make PTOs a persistent hazard on farms and ranches.
Injuries that can be sustained from PTO incidents include severe contusion, cuts, spinal and neck injuries, dislocations, broken bones, amputations and scalping. Some incidents can result in fatalities.
Basic safety recommendations include the following:
- Never step over a rotating shaft.
- Make sure that your tractor and machinery have the proper shields including
PTO master shields and driveline shields.
- Do not wear loose fitting clothing and keep long hair tied back and secured under a hat when working around equipment.
Learning Objectives for the Demonstration
- To learn about the hazards of the turning parts on the PTO.
- Describe the basic structure and components of a PTO
- Describe the types of shields and guards available for the PTO
- Understand prevention steps to take to reduce the risk of a PTO-related injury.
- GKN Walterscheid Demonstration PTO Shaft
- Cordless electric drill (with 500 rpm, adjustable clutch and reverse)
- A long-sleeve shirt.
Demonstration Steps and Key Discussion Points
- Set up the demonstration by placing the Walterscheid PTO shaft on a hard level surface (Figure 1). Check the equipment to be sure it is functioning properly; the PTO shield should rotate and telescope easily and the bell should be easily removable.
Key discussion points: Discuss the function of the PTO and its structure and components.
- Have the battery for the cordless drill at full power. Be sure the clutch is set at its lightest setting so it will slip easily if anything goes wrong, and the reversing switch should be set so the drill rotates in the appropriate direction. (If the unit will be left unattended for a moment, the switch should be locked in the off position, if possible.)
- Check the shirt sleeve to be sure it is buttoned or that the catching hole is open and not ripped beyond use.
- To perform the demonstration - Mention that the drill spins at about the same speed of an actual tractor PTO. Spin the PTO shaft with the drill (Figure 2) and point out that when it is functioning properly, the guard does not rotate (a chain may also hold it in place) and there is nothing protruding to catch clothing.
Key discussion points: Discuss with the audience the information above regarding PTO entanglements. (Be sensitive to the age and sensitivity of individuals in the audience when describing injuries common in a PTO entanglement. Get their attention but don't cause them to tune you out because of your graphic description.
- Stop the drill and remove it from the shaft so you can twist the bell on the opposite end of the shaft and pull it back revealing the universal joint and attaching bolt. Point out that if and when the shield is broken or removed and not replaced, these parts are exposed to catch anything that comes near them.
Key discussion points: Discuss proper PTO shielding.
- Spin the shaft with the drill again (being sure no one is near the unit) and hold the shirtsleeve where the long attaching bolt can catch either the hole you have made or the placket of the sleeve. Hold the sleeve loosely and let the spinning PTO shaft pull it easily from your fingers. Mention that in an average reaction time the sleeve will be wrapped seven times around the shaft before the victim even knows it.
Key discussion points: Discuss proper clothing to wear when working around PTO. Discuss the dangers of long hair and how it should be tied back and secured under a hat.
- Reverse the drill and slowly unwind the sleeve and repeat the demonstration if you feel it would be beneficial. When you are done, put the sleeve inside the U- joint bell and replace the bell to its original position and twist it slightly to lock it in place.
Figure 1. Walterscheid PTO demonstration and drill.
Figure 2. Cordless drill attached to the demonstration.
Take-home Points for the Demonstration
- Understand the function and parts of the PTO.
- Understand the hazards related to PTO entanglements.
- Understand prevention strategies
We have provided a one page evaluation which has been designed to be used with participants after each lesson. The answer key is offered below.
Evaluation Questions Answer Key
- Wear snug fitting clothing with no dangling strings or shoelaces
- Entanglements usually occur when repairs or adjustments are being made to machine and PTO is left engaged.
- A rotating drive shaft that transfers tractor engine power to implements.
- (student response)
- (student response)
For more information about PTO safety and recommendations, visit the resources below.
Murphy, D. (2014) Power Take-Off (PTO) Safety. Penn State Extension. Power take-off safety. (2012) Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice.