Mechanical Hazards: Thrown Objects

Ag Safety and Health April 13, 2018 Print Friendly and PDF


Bush Hog Mower
Bush Hog Mower. Photo Source: Penn State University



Use the following format to cite this article:

Mechanical hazards: Thrown objects. (2013). Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from


A thrown-object hazard is typically associated with equipment that mows, chops, or cuts crops in an open field, barnyard, or yard. Thrown-object hazards typically exist with pieces of equipment, such as rotary mowers, cutters, and shredders, that have rotating fans or knife blades. Machines that chop or grind feed can pose a hazard as well. Thrown-object incidents have also occurred with manure spreaders.

When equipment passes over pieces of metal or wire, sticks, rocks, and so on, the objects can become projectiles that fly a great distance with extreme force. An object can be thrown from the discharge chute of a rotary mower, for example, at speeds of up to 200 mph. 

Thrown objects can cause property damage and serious injury to people or animals in the vicinity. Potential injuries from thrown objects include contusions, abrasions, lacerations, bruises, and eye and head injuries.

Safety Precautions

Listed below are ways that you can reduce the risk of a thrown-object incident:

  • Identify those types of machines that may throw objects.
  • Make sure machine guards or shields are securely in place and properly maintained.
  • Make sure a machine and all its moving parts are completely stopped before nearing the discharge area.
  • Never point a mower discharge chute toward people, pets, homes, structures, streets, or vehicles.
  • Always wear eye protection when working with machinery that cuts, grinds, or chops material.
  • Be aware of the distance and direction of potential thrown objects.
  • When you are working with machinery that can throw objects, do not allow others in the area.


Click here to view a video about thrown objects from the Pennsylvania State University’s Agricultural Safety and Health Program.


Use the following format to cite this article:

Mechanical hazards: Thrown objects. (2013). Farm and Ranch eXtension in Safety and Health (FReSH) Community of Practice. Retrieved from



Agricultural equipment and machine hazards. (2016) The Ohio State University. Retrieved from

American Society of Agricultural and Biological Engineers, 2008. ANSI/ASAE S493.1. Guarding for agricultural equipment. St. Joseph, MI. Retrieved from

Reviewed and Summarized by:
Linda M. Fetzer, Pennsylvania State University –
Liz Kenton, University of Vermont
Dennis J. Murphy, Pennsylvania State University (Has since retired)
Michael Pate, Pennsylvania State University
Aaron M. Yoder, University of Nebraska Medical Center -

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.