Mantel Clock Speed Adjustment

Mechanical clocks are very reliable but will always need a mechanism to regulate the speed of the clock.  Most notably and visually, that is accomplished with the use of a pendulum.  Most people will recognize the familiar long wood or lyre pendulum on grandfather and wall clocks.  Contemporary mechanical mantel clocks, however, use a different mechanism to regulate the speed of the clock.  Most commonly, the regulation is accomplished with the use of a balance wheel.  More sophisticated models might use a platform escapement instead of a balance wheel, but they are similar.  Indeed, a balance wheel functions the same as the familiar pendulum.

 There are two notable times when adjusting the speed of the balance wheel is helpful.  The first is when the clock is brand new and has not been run before.  We recommend letting the mantel clock run for a couple of days to see how accurate the time is.  It may be helpful to slightly adjust the speed at that time.  There are other times when you may notice the speed needs adjusting, such as seasonal changes.  Humidity changes can affect the speed of the clock. 

 Adjusting the speed of a balance wheel in a new mantel clock is accomplished by slightly turning the rating screw.  The rating screw is located on the balance wheel assembly, as pictured in our reference.  A small, thin regular screwdriver is useful here.  Alternatively, an eyeglass screwdriver can also be used.  Turn this screw clockwise to slow the balance wheel down and turn the screw counterclockwise to speed the balance wheel up.  Small increments are all that is needed.  It will then be necessary to reset the minute hand to the exact, correct time by moving the minute hand clockwise.  It will also be necessary to let 24 hours pass before further adjustments are made so that the balance wheel can work the adjustment out.