Mechanical Hazards: Stored Energy

Hydraulic Line Check

(Source: Pennsylvania State University. Agricultural Safety and Health)


Use the following format to cite this article:

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


Stored-energy hazards occur when confined energy is unintentionally released. A spring is a classic example of the release of stored energy: A compressed spring expands with great force when released, and a stretched spring quickly contracts. Springs, hydraulics, and pneumatics move and control machines and implements that are part of agricultural equipment. The sudden pressurization or depressurization of such stored-energy systems can result in incidents that cause serious injury or death.

There are many examples of stored energy in agricultural equipment:

  • Compressed air 
  • Pressure washers
  • Springs
  • Winches
  • Hydraulic, pneumatic, and electrical systems

Compressed air and fluids are used for tire inflation and power washing and in hydraulic cylinders. Springs are used as shock absorbers and as a means of keeping belts tight. Winches and hydraulic systems are used to lift or change the position of implements. 

Potential Injuries

Injuries that can result from the unintentional release of stored energy include burns, contusions, abrasions, lacerations, injection injuries (as from hydraulic fluid), and crushing injuries. Amputation of a limb may be required if an injection injury is not immediately treated at a hospital.

Safety Precautions

The list below outlines ways of reducing the risk of a stored-energy incident.

  • Identify machines that may have stored energy.
  • Before operating a machine that uses hydraulic or water pressure, examine the hoses and fittings for wear.
    • Pass a piece of cardboard (shown above) or flat board along the hydraulic hoses to check for leaks. Do not use a hand to check for leaks. Gloves do not provide protection from hydraulic leaks under pressure.
  • Turn off the engine and relieve hydraulic pressure before disconnecting hydraulic hoses or completing repairs.
  • Lower hydraulic components to the ground before shutting off the engine and dismounting the equipment.
  • Never walk under an implement or component supported by hydraulics or winches.
  • Regularly check winch cables for wear.
  • Before executing maintenance on hydraulic implements, put in place supports, jacks, stands, or blocks to prevent unintentional movement of the implements.
  • Know what direction a spring will move when released and how it might affect other machine parts, and stay out of the spring’s path.
  • Wait for free-wheeling parts such as flywheels, cutter heads, hammer mills, rotary mower blades, and fans to come to a complete stop before touching them.
    • This may take up to two and a half minutes.
  • Never try to stop a free-wheeling winch handle by catching it.
  • Never point a compressed-air nozzle or pressure-washer nozzle toward a person, including yourself.
    • Make sure others are well out of range of flying debris when using such equipment.


Click HERE to view a video about stored energy from Pennsylvania State University’s Agricultural Safety and Health Program.

Click HERE to purchase a video from the Fluid Power Safety Institute on managing hydraulic oil injection injuries.


Use the following format to cite this article:

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



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

Cyr, D. & Johnson, S. (2002) Dangers of agricultural machinery. Maine Farm Safety Program. Retrieved from

Harshman, W., Yoder, A., Hilton, J., & Murphy, D. (2011) Mechanical hazards. HOSTA Task Sheet 3.1. Pennsylvania State University Agricultural and Biological Engineering Department. Retrieved from….

Safety note #16: Hydraulic safety. (2004) University of California, Agricultural and National Resources, Environmental Health and Safety. Retrieved from


Reviewed and Summarized by:
Linda M. Fetzer, Pennsylvania State University –
Willard Downs, University of Missouri
Dennis J. Murphy, Pennsylvania State University (Has since retired)
Robert A. Schultheis, University of Missouri
Aaron M. Yoder, University of Nebraska Medical Center –