MACHINE SAFETY: How to Comply with OSHA Power Transmission Belts Standard

Date First Published on SafetySmart Compliance: April 5th, 2012
Topics: Machine Guarding |

transmission belt articleThe OSHA standard on Power Transmission Belts, Sec. 1910.219, covers all power transmission belts, e.g., flat belts, round belts, V-belts, etc. Here’s a look at the requirements.

Belts Not Covered by the Standard

The standard does not cover the following belts when they’re operating at 250 feet per minute or less:

  • Flat belts 1 inch or less in width;
  • Flat belts 2 inches or less in width that don’t have metal lacings or fasteners;
  • Round belts 1/2 inch or less in diameter;
  • Single strand V-belts with a width of 13/32 inch or less; and

Guarding the Prime Mover Power Source

The standard requires proper guarding of prime movers, i.e., steam, gas, oil and air engines, motors, steam and hydraulic turbines and other equipment used as source of power.

Flywheels located so that any part is 7 feet or less above the floor or platform must be guarded:

  • With an enclosure of sheet, perforated, or expanded metal, or woven wire;
  • With guard rails no less than 15 inches or more than 20 inches from the rim—there must also be a standard toeboard when the flywheel extends into pit or is within 12 inches of the floor; or
  • When the upper rim of a flywheel protrudes through a working floor, it must be entirely enclosed or surrounded by a guardrail and toeboard.

For flywheels with smooth rims 5 feet or less in diameter that can’t be guarded using the above methods, can instead be guarded by attaching a disk attached to the flywheel so as to cover the spokes of the wheel on the exposed side and present a smooth surface and edge, at the same time providing means for periodic inspection. An open space, not exceeding four 4 inches in width, may be left between the outside edge of the disk and the rim of the wheel to facilitate turning the wheel over. Where a disk is used, the keys or other dangerous projections not covered by disk shall be cut off or covered.

Adjustable guards used for starting the engine or for running the adjustment may be provided at the flywheel of gas or oil engines but a slot opening for jack bar isn’t allowed.

Flywheels located above working areas must be guarded by installing guards of sufficient strength to hold the weight of the flywheel in the event of a shaft or wheel mounting failure.

Cranks and connecting rods exposed to contact, must be properly guarded with machine guards or a guardrail. Tail rods or extension piston rods must be properly guarded with machine guards  or a guardrail on sides and end, with a clearance of no less than 15 nor more than 20 inches when the rod is fully extended.

Guarding of Shafting

Each continuous line of shafting must be secured in position against excessive endwise movement.

All exposed parts of horizontal shafting 7 feet or less from floor or working platform, except runways used exclusively for oiling, or running adjustments, must be protected by a stationary casing enclosing shafting completely or by a trough enclosing sides and top or sides and bottom of shafting as location requires.

Shafting under bench machines must be enclosed by a stationary casing, or a trough at sides and top or sides and bottom, as location requires. The sides of the trough must come within at least 6 inches of the underside of the table (or floor), and extend at least 2 inches beyond the shafting or protuberance.

Vertical and inclined shafting 7 feet or less from floor or working platform, except maintenance runways, must be enclosed with a stationary casing made of appropriate materials or a proper guardrail.

Guarding of Pulleys

Pulleys with any part 7 feet or less from the floor or working platform must be properly guarded. Pulleys serving as balance wheels (e.g., punch presses) on which the point of contact between belt and pulley is more than 6 ft. 6 in. from the floor or platform may be guarded with a disk covering the spokes.

Unless the distance to the nearest fixed pulley, clutch or hanger exceeds the width of the belt used, a guide must be provided to prevent the belt from leaving the pulley on the side where insufficient clearance exists.

Pulleys can’t be used if they have cracks, or pieces broken out of rims.

Guarding of Belts, Ropes and Chain Drives

Where both runs of horizontal belts are 7 feet or less from the floor level, the guard must extend to at least 15  inches above the belt or to a standard height. Exceptions: Where both runs of a horizontal belt are 42 inches or less from the floor, the belt must be fully enclosed; and  in powerplants or power-development rooms, a guardrail may be used in lieu of the guard.

Overhead horizontal belts (and overhead chain and link belt drives) with lower parts 7 feet or less from the floor or platform, must be guarded on the sides and bottom.

Horizontal overhead belts more than 7 feet above the floor or platform must be guarded for their entire length if:

  • The belts are located over passageways or work places and traveling 1,800 feet or more per minute;
  • The center to center distance between pulleys is 10 feet or more; and
  • The belt is 8 inches or more wide.

If it’s possible for persons to pass between the upper and lower runs of horizontal belts, the passage must be completely barred by a guardrail or other barrier. But where passage is considered necessary, there must be a platform over the lower run guarded on either side by a railing completely filled in with wire mesh or other filler, or by a solid barrier.

The upper run must be guarded to prevent it from coming into contact with either the worker or the objects he/she carries. (In powerplants only the lower run of the belt need be guarded.)

Guards for horizontal overhead belts must run the entire length of the belt and follow the line of the pulley to the ceiling or be carried to the nearest wall, thus enclosing the belt effectively.

Vertical and inclined belts must be enclosed by a proper guard. All guards for inclined belts must be arranged so that a minimum clearance of 7 feet is maintained between belt and floor at any point outside of the guard.

Vertical belts running over a lower pulley more than 7 feet above floor or platform must be guarded at the bottom in the same manner as horizontal overhead belts, if:

  • The belts are located over passageways or work places and traveling 1,800 feet or more per minute; and
  • The belt is 8 inches or more wide.

Guarding of Gears, Sprockets and Chains

Gears must be guarded by a complete enclosure, a standard guard at least 7 feet high extending 6 inches above the mesh point of the gears or a band guard covering the face of gear and having flanges extended inward beyond the root of the teeth on the exposed side or sides.

Sprocket wheels  (other than manually-operated sprockets) and chains must be enclosed unless they’re more than 7 feet above the floor or platform. Where the drive extends over other machine or working areas, protection against falling must be provided. This subparagraph does not apply to manually operated sprockets.

The driving point of all friction drives when exposed to contact must be guarded. All arm or spoke friction drives and all web friction drives with holes in the web must be entirely enclosed. All projecting belts on friction drives where exposed to contact must be guarded.

Construction, Design and Position of Guards

Standard conditions must be secured by the use of expanded metal, perforated or solid sheet metal, wire mesh on a frame of angle iron or iron pipe securely fastened to floor or to frame of machine. All metal must be free from burrs and sharp edges. Expanded metal, sheet or perforated metal and wire mesh must be securely fastened to the frame.

Wood guards aren’t allowed except in:

  • The woodworking and chemical industries;
  • Industries where the presence of fumes or manufacturing conditions would cause the rapid deterioration of metal guards; and/or
  • Construction work and work in outdoor locations where extreme cold or heat make metal guards and railings undesirable.

Except for horizontal overhead belts, rope, cable or chain guards more than 7 feet above the floor, or platform. All guards must be rigidly braced every 3 feet or fractional part of their height to some fixed part of machinery or building structure. Where the guard is exposed to contact with moving equipment additional strength may be necessary.

Guards for horizontal overhead belts must run the entire length of the belt and follow the line of the pulley to the ceiling or be carried to the nearest wall, thus enclosing the belt effectively. But where belts are so located as to make it “impracticable” to carry the guard to wall or ceiling, construction of guard must be such as to enclose completely the top and bottom runs of belt and the face of pulleys.

Suitable reinforcement must be provided for the ceiling rafters or overhead floor beams, where necessary, to sustain safely the weight and stress likely to be imposed by the guard.

The interior surface of all guards, i.e., the surface of the guard with which a belt comes in contact, must be smooth and free from all projections, except where construction demands it.

Overhead belt guards must be at least 1/4 wider than the belt they protect, except that this clearance need not in any case exceed 6 inches on each side.

Guardrails must be 42 high, with mid-rail between top rail and floor. Posts can’t be more than 8 feet apart and must be permanent and substantial, smooth, and free from protruding nails, bolts and splinters. The upper rail must be 2 by 4 inches, or made of two 1 by 4 strips, one at the top and one at the side of posts. The mid-rail may be 1 by 4 inches or more.

Toeboards must be 4 inches or more in height and made of wood, metal or metal grill not exceeding 1 inch mesh.

Maintenance of Guarding Equipment

All power-transmission equipment must be inspected at intervals at least every 60 days and kept in good working condition at all times.

Shafting must be kept in alignment, free from rust and excess oil or grease.

Bearings must be kept in alignment and properly adjusted.

Hangers must be inspected to ensure that all supporting bolts and screws are tight and that supports of hanger boxes are adjusted properly.

Pulleys must be kept in proper alignment to prevent belts from running off.

Belts, lacings and fasteners must be inspected and kept in good repair.

Machinery must be oiled when it’s not in motion, wherever possible. The regular oilers must wear tight-fitting clothing to avoid ensnarement.