Mechanical clocks typically require some manual input to maintain their accurate timekeeping processes. Generally speaking, a clock that requires winding will have either a one-day, eight-day or 31-day movement. Although clocks may run a few days longer than specified, they should be wound daily, weekly or monthly, depending on the type of clock, to assure the most accurate time.

Old clocks  on brick wall
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How To Wind A Clock

Parts of the Mechanical Clock

Mechanical clocks (as opposed to digital ones, for example) have four component parts in common:

  1. The escapement: This is a repetitive action of some kind that lets power escape, literally, but only in small portions as opposed to a steady "all at once" flow.
  2. The power: Generally supplied initially by a falling weight and later on occasion by a coiled spring.
  3. Indicators: Dials, hands and bells or chimes.
  4. The going train: Gear wheels that help set the rotational speed of the wheels that connect between the power and the indicators.

Winding the clock resets the power and the escapement then controls the release of that power in a steady, prescribed pattern. The result is accurate timekeeping.

Windup Clocks and Keys

Clocks that require actual winding will have anywhere from one to three winding holes on the body of the clock, often in the back facing. Generally speaking, if the clock has a single hole, that hole controls the main time spring. If there are two holes, one is for the time spring and one is for the hourly chime. Some clocks also have a third hole, which governs the quarter-hour chime tones.

Movement length should be specified by the manufacturer in the original packaging when you buy the clock. If the clock is a gift or a bequest, you can probably find out quickly what its movement length is with a little internet research or by asking a horologist (a clockmaker or repairer).

Typical movement lengths are 24 hours, eight days and 31 days. Smaller mantle clocks have predominantly eight-day movements, while larger pendulum clocks typically have 31-day movements.

Winding Up Your Wall and Mantel Clocks

To wind up your wall or mantel clock, first locate the time spring hole. If you have more than one keyhole in your clock, this is usually the one located farthest to the right as you're looking at the clock's surface. However, models can vary, so you may need to experiment a bit with this.

Insert your winding key into the appropriate hole. You'll want to test with the key to find out whether to turn clockwise or counterclockwise. Whichever direction the key turns freely is the right one. If the key won't move easily in either direction, this indicates the clock doesn't need to be wound. Otherwise, turn the key until you meet resistance. Don't force the key further.

In clocks with more than one keyhole, the left-most hole usually controls the hourly chime, and in clocks with three keyholes, the center keyhole is typically for the quarter-hour chime, although again this can vary from model to model.

Clocks With Hanging Weights

If your clock has functional hanging weights and a pendulum, you won't need a key for winding your clock. Instead, you'll need to raise the weights using the special crank that comes with the clock.

While you're cranking the weights up to wind the clock, take care not to lift the weights by hand while doing so. You'll want to do this about once a week if the weights were properly raised beforehand. Each thorough wind should result in a week of accurate timekeeping.