Flagpole mechanics – how the halyard, pulley and hinged base work

A flagpole is a simple machine that needs to work every time. A halyard that jams on a flag day, or a flag that gets stuck at half-mast, is noticed. Here is an overview of how the mechanics work and which signs can point to wear.

The halyard and the pulley

The most common arrangement is a closed halyard loop that runs over a pulley, or sheave, at the top of the pole.

1. The flag is attached to the line with flag clips, one at the flag’s upper corner and one at the lower.
2. When one side of the line is pulled, the flag goes up, and when the other side is pulled, it comes down.
3. When the flag is at the top, or at the height for half-mast, the line is made fast on the cleat, often with a few figure-of-eight turns and a finishing half hitch.

According to Riksarkivet’s recommendations, the flag is raised properly to the top, up to the finial, with the halyard taut.

External and internal halyard

• With an external halyard, the whole loop runs outside the pole. It is easy to see and fix, but the line can slap against the pole and can be reached by anyone.
• With an internal halyard, the line runs down inside the pole, and the cleat or a winch sits behind a lockable hatch. It gives protection against theft and vandalism and a quieter pole. It is worth bearing in mind that threading a new line takes more work if it breaks inside the pole.

Rotating top

An ordinary top stands still, and when the wind changes direction, the pennant or flag can wrap itself around the pole. A rotating top or pennant rotator is mounted on bearings so that it turns with the wind. This reduces wrapping and wear, especially for a pennant that stays up around the clock.

The hinged base

A hinged pole sits in a base with two fixing points. One acts as a hinge, and when the other is released, the pole can be lowered around the hinge.

It is worth bearing in mind that

• the pole needs clear space equal to its height in the direction it is lowered
• taller poles are often handled by at least two people, one at the top end and one at the base
• aluminium and steel poles conduct electricity, which makes the distance to power lines important
• the manufacturer’s instructions describe the order of the bolts.

The effect of the wind

It is the flag, not the pole, that catches most of the wind. A flapping flag pulls on the top with a force that rises sharply with wind speed and flag size. That is why

• many poles are designed for a maximum flag size, see flag sizes
• a glass-fibre pole bends visibly in strong wind, which is normal
• Riksarkivet mentions that a smaller storm flag can be raised in very strong wind
• the load is greatest on the foundation at ground level, where the whole lever arm of the pole acts.

More about strength and wind load in the guide to flagpole safety.

Signs of wear

• The halyard has turned pale, frayed or stiff.
• The flag runs stiffly or jerks when being raised.
• The pulley squeaks or does not turn.
• The cleat is loose.
• The pole leans or moves at the base.

More about common faults and solutions in the guides to flagpole maintenance and flagpole repair.