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726 Introduction to Machine Guarding
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Hazardous Mechanical Motions and Actions

A wide variety of mechanical motions and actions may present hazards to the worker.

Image showing saw cutting large piece of metal
This is an example of a saw using cutting actions and transverse motions to cut a large piece of metal.

These can include the movement of rotating members, reciprocating arms, moving belts, meshing gears, cutting teeth, and any parts that impact or shear. These different types of hazardous mechanical motions and actions are basic in varying combinations to nearly all machines, and recognizing them is the first step toward protecting workers from the danger they present.

The basic types of hazardous mechanical motions and actions are:

  • Motions
    • rotating (including in-running nip points)
    • reciprocating
    • transversing
  • Actions
    • cutting
    • punching
    • shearing
    • bending

Knowledge Check Choose the best answer for the question.

1-2. Which of the following is a hazardous mechanical motion?