Nelson & Associates :: Machine Guarding :: Power Transmission

Machine Guarding Definitions:
Power Transmission

Power Transmission.

All mechanical components including gears, cams, shafts, pulleys, belts, and rods that transmit energy and motion from the source of power to the point of operation;1 to equipment or a machine.2

Other Machine Guarding Definitions

  • Guarding / Safeguarding.

    Any means of effectively preventing personnel from coming in contact with the moving parts of machinery or equipment that could cause physical harm to the personnel.1,2

  • Guard.

    The word guard often refers exclusively to barriers designed for safeguarding at the point-of-operation. Guards include…enclosure guards, fixed-barrier guards, interlocked-barrier guards, and adjustable-barrier guards.2

  • Device.

    A device is a mechanism or control designed for safeguarding at the point-of-operation. Devices include presence-sensing devices, movable-barrier devices…two-hand-trip devices, and two-hand-control devices.2

  • Enclosures.

    Guarding by fixed physical barriers that are mounted on a machine to prevent access to the moving parts.1,2 Enclosures are most effective when designed as part of the machine, but they can be bolted or welded to the frame or the floor.2

  • Fencing.

    Guarding by means of a fence or rail enclosure that restricts access to a machine except by authorized personnel.1 Such fence or rail should be locked to positively restrict access.2

  • Point of Operation.

    That area on a machine where material is positioned for processing or change by the machine,1 where work is actually being performed on the material.

  • Functional Components.

    Functional components in agricultural equipment, such snapping and husking rolls, straw spreaders and choppers, cutter-bars, rotary beaters, mixing augers, feed rolls, conveying augers, rotary tillers, and similar units [in agriculture and general industry], which must be exposed for proper function.3 Such components shall be guarded to the fullest extent that will not substantially interfere with functioning of the component.3

  • Ingoing Nip Points.

    A hazard area created by two or more mechanical components rotating in opposite directions in the same plane and in close conjunction or interaction.1

  • Pinch Point.

    A pinch point is any place where a body part can be caught between two or more moving mechanical parts.2

  • Shear Points.

    A hazard area created by a reciprocal (sliding) movement of a mechanical component past a stationary point on a machine.1,2

  • Guarding by Location.

    Guarding that is the result of the physical inaccessibility of a particular hazard under normal operating conditions or use.1 Both fencing and location are very limited as safeguarding techniques and are permitted only if caution restrictions can be met.2

  1. National Safety Council, Accident Prevention Manual for
    Industrial Operations
    , 7th Edition, 1974.
  2. National Safety Council, Accident Prevention Manual for Business &
    Industrial Operations
    , 12th Edition, 2001.
  3. 29 CFR 1928, 1928.57 – Guarding of Farm Field Equipment,
    Farmstead Equipment, and Cotton Gins.

See the following Nelson & Associates Fact Sheets:

Also search "machine guarding" at to include

© Nelson & Associates, 2021