Machine Safety Basics


Thousands of operators have lost limbs — and lives — at the hands of dangerous machines. Anyone who is operating or working around machinery should be able to identify potential hazards and/or compliance issues. Understanding the mechanical components of machinery and the motions that occur at or near these components will help prevent countless injuries.

Key Components

The mechanical components that may exist on your equipment generally fall into these categories:

  • The point of operation is the area where the machine performs work. Mechanical actions that occur at the point of operation include cutting, shaping, boring and forming.
  • The power-transmission apparatus includes all components of the machine’s mechanical system that transmit energy.
  • Other moving parts include the areas of the machine that move while the machine is operating, such as reciprocating, rotating and transverse moving parts, as well as lead mechanisms and auxiliary parts of the machine.

Mechanical Motion

A machine’s components are hazardous largely because of the mechanical motions they make. Basic types of mechanical motion are:

  • Rotating motion, such as action generated by rotating collars, couplings, cams, clutches, flywheels, shaft ends and spindles, that may grip clothing or otherwise force a body part into a dangerous location. Projections, such as screws, on the rotating part increase the hazard potential.
  • Reciprocating motion is back-and-forth or up-and-down movement that may strike or entrap a worker between a moving part and a fixed object.
  • Transversing motion is movement in a straight, continuous line that could strike or catch a worker in a pinch or shear point created by the moving part and a fixed object.
  • Cutting action occurs by sawing, boring, drilling, milling, slicing or slitting machinery.
  • Punching action begins when power causes the machine to hit a slide (ram) to stamp or blank metal or some other material.
  • Shearing action is powered slide or knife movement used to trim or shear metal or other materials.
  • Bending action is power applied to a slide to draw or stamp metal or other materials.
  • In-running nip points, also known as “pinch points,” are created when two parts move together and at least one moves in rotary or circular motion.

When evaluating activities for potential hazards, consider the entire operation, the activities associated with the operation, and the potential for worker injury. Once you have identified the hazards, it is time to ensure you have appropriate guards in place. Work practices, employee training and administrative controls can play a role in preventing and controlling machine hazards.

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