Setting Pendulum and Radio-Controlled Clocks: Step-by-Step

01. September 2026

A pendulum clock losing two minutes a day, or a chime striking the wrong hour: these problems can be solved in most cases without tools or a professional repair shop. The decisive adjustment is almost always the regulating screw on the pendulum lens; for radio-controlled clocks, antenna alignment is also a factor. This article describes both methods, explains the time change, and lists the most common mistakes when adjusting.

The following sections cover mechanical pendulum movements and radio-controlled pendulum movements equally. If you have a pure quartz wall clock without a pendulum, you can find the basics on movement types in the Clock Movement Lexicon: Quartz, Automatic, Manual Wind, and Solar.

How a pendulum movement works and why accuracy depends on the pendulum

In a mechanical pendulum movement, the pendulum acts as the timekeeper. It swings with a period that depends solely on its length: the longer the pendulum, the slower it swings, and the slower the clock runs. This relationship dates back to Galileo Galilei's observation and remains valid today.

Inside the movement, a so-called escape wheel ensures that the gear train advances in the exact rhythm dictated by the pendulum. With every swing to the left and right, the anchor (the fork-shaped component between the escapement and the pendulum) releases the wheel by one tooth. If the pendulum is too short, the gear train turns faster, and the hands run ahead. If it is too long, the clock lags behind.

In a radio-controlled pendulum movement, the mechanical pendulum is merely decorative: it is driven by a quartz movement or directly by the receiver module. The accuracy is provided by the radio signal; the pendulum itself has no effect on the displayed time. You should know this difference before spending hours turning the regulating screw.

Adjusting pendulum length: the regulating screw on the lens weight

On almost all mechanical pendulum clocks, there is a disc at the lower end of the pendulum, the so-called lens weight. Below or behind it is a knurled nut or adjustment screw. This screw changes the position of the lens and thus the effective oscillation length of the pendulum.

Screw direction and its effect

Direction of rotation of the adjustment screw	Lens moves	Pendulum becomes	Clock runs
Clockwise (right)	upwards	shorter	faster
Counter-clockwise (left)	downwards	longer	slower

The rule of thumb: For most standard wall clocks, half a turn of the adjustment screw corresponds to a deviation of about one minute per day. If you want to measure precisely, set the clock exactly to the correct time one day, wait 24 hours, and check the deviation before making corrections. More on the procedure for regulation is explained in detail in this guide.

Starting the pendulum and checking balance

For the pendulum to swing evenly, the clock must hang perfectly vertically. If you hear two different ticking sounds ("tick-tock" sounds uneven), the clock is slightly tilted. In this case, tilt the clock slightly to the left or right until the ticking sounds even. Then readjust the suspension accordingly.

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Large radio-controlled clock: check reception, align antenna, trigger manual sync

Radio-controlled wall clocks receive the time signal from the long-wave transmitter DCF77, which is operated in Mainflingen near Frankfurt. The signal has a range of about 2,000 kilometers and reliably reaches almost all of Central Europe under normal conditions. Problems almost always arise from local sources of interference or an unfavorable position of the clock.

Common reception interferers

Source of interference	Typical symptoms	Remedy
Reinforced concrete walls	No sync, incorrect display	Hang the clock near a window
Switching power supplies, LED drivers	Sporadic errors, wrong minutes	Increase distance from routers, power supplies
Metal frames, radiators	Weak signal, long search	Place the clock away from metal parts
Incorrect antenna alignment	Signal not found	Rotate the clock by 90 degrees

The internal ferrite antenna of most radio-controlled wall clocks is optimized for a specific orientation. Since the antenna is most sensitive perpendicular to the transmitter direction, rotating the clock by 90 degrees can significantly improve reception quality. The DCF77 transmitter is located northwest of most German locations; a clock on a south wall often receives better than on an east wall.

Triggering manual sync

Most large radio-controlled clocks search for the signal automatically once a day, often at night between 12:00 AM and 4:00 AM. If you don't want to wait, many models allow you to start an immediate reception attempt by briefly pressing the reset or sync button. The clock will then show a search indicator for a few minutes; if reception is successful, it will automatically set the hands to the correct time.

More on the topic of radio-controlled wall clocks in everyday life is explained in our article Radio-controlled wall clocks for the office: accurate to the second without manual setting.

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Time change in autumn and spring: what runs automatically, what remains manual

Radio-controlled pendulum clocks that receive the DCF77 signal adjust themselves completely automatically during the time change. The signal carries an announcement bit that informs the movement one hour before the change. The hands move automatically. The only requirement: the clock must have reception on the night of the change.

Adjusting mechanical pendulum clocks manually

For mechanical pendulum movements without radio reception, the time change must be done by hand. The recommended procedure differs depending on the direction:

Spring (one hour forward): Slowly turn the minute hand one full turn clockwise. For clocks with a chime, wait until the chime has finished striking after every half and full hour before continuing to turn. Otherwise, the chime and hands may get out of sync.
Autumn (one hour back): Never turn the minute hand counter-clockwise. This damages the switching mechanism. Instead, turn the hand eleven turns clockwise, which corresponds to eleven hours, and wait for the chime every hour.

Alternatively, for clocks with a winding key, you can stop the pendulum until the time is correct by itself: in autumn, simply stop the pendulum and restart it after an hour. This method is gentler on the movement.

Muting or adjusting the chime and strike

Many pendulum clocks strike on the hour (number of hours) and on the half-hour (once). Models with a Westminster chime also play a four-tone melody on the hour and half-hour, based on the famous chimes of the London Parliament building.

Synchronizing chime and hands

If the number of strikes does not match the displayed hour, there is an offset in the switching mechanism. Remedy: Carefully turn the hour hand to the hour indicated by the chime without moving the minute hand. Then set the time regularly using the minute hand.

Activating night shut-off

Most modern pendulum clocks and large radio-controlled clocks have a night shut-off that automatically mutes the chime between a set time (often 10:00 PM and 7:00 AM). This function is activated via a small slide switch on the back or side of the case. If such a switch is missing, you can permanently dampen the chime by carefully placing a small piece of felt on the strike hammer. This is reversible and does not damage the movement.

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Common errors and what they mean

Symptom	Probable cause	Solution
Clock stops after a few minutes	Pendulum swung too far, clock is hanging crooked, movement needs winding	Align the clock, start the pendulum in the center, wind the mainspring
Clock runs several minutes fast daily	Pendulum set too short	Turn the regulating screw to the left (counter-clockwise)
Clock runs several minutes slow daily	Pendulum set too long	Turn the regulating screw to the right (clockwise)
Radio-controlled clock shows wrong time after restart	No signal received, time zone set incorrectly	Change position, trigger manual sync, check time zone setting
Chime strikes wrong number of hours	Hour hand and striking mechanism not synchronized	Set the hour hand to the struck hour, then reset
Pendulum stops even though the clock is wound	Escapement blocked, lubricant dried out	Professional repair or cleaning of the movement due

If you own an AMS large clock and would like to learn more about the model range and its movement characteristics, you can find an overview in our article AMS Wall Clocks: German Large Clock Tradition at a Glance.

Frequently Asked Questions

How often do I have to wind a mechanical pendulum clock?

That depends on the spring mechanism. Most living room pendulum clocks with a spring drive have a power reserve of 8 days. Clocks with a weight drive run for a similar length of time but must be wound using a cord. It is recommended to choose a fixed day of the week to wind the clock so that the movement always runs in the upper third of the power reserve and runs more evenly.

My radio-controlled pendulum clock does not synchronize. Why is that?

The most common cause is a disturbed reception situation: reinforced concrete, metal radiators in the immediate vicinity, or electronic devices such as routers and LED power supplies emit interference signals. Try hanging the clock by the window as a test and triggering a manual sync there. If reception is successful there, the previous location is the problem. Furthermore, experience shows that DCF77 receives most reliably in the early morning hours, as the noise level in the household is lowest then.

Can I turn the minute hand of a mechanical pendulum clock counter-clockwise?

Generally, no. Most mechanical striking mechanisms are not designed to be moved counter-clockwise. This can damage the switching mechanism for the strike count. In autumn, when the clock is to be set back one hour, the correct way is: either stop the pendulum for one hour or turn the minute hand eleven hours clockwise.

Why does my Westminster chime strike incorrectly after the time change?

The Westminster striking mechanism counts the hours internally. If the chime for each hour has not finished playing when the hands are moved forward, the internal strike-counting wheel gets into an incorrect position. This can be corrected by running through the time completely again and waiting at each full hour until the chime has finished ringing. After that, the hands and chime will be in sync again.

How do I know if my pendulum clock has a mechanical or a radio-controlled pendulum movement?

A mechanical pendulum movement requires regular winding via a key or chain and does not show a battery compartment on the back. A radio-controlled pendulum movement runs on batteries (usually 1.5-volt AA cells) and has no winding lock. In radio-controlled pendulum clocks, the pendulum moves electrically and has no influence on the displayed time. The product description or the imprint on the movement usually states the drive type.

Is it normal for a mechanical pendulum clock to deviate by one to two minutes daily?

A deviation of one to two minutes per day is quite common for older or cheaper mechanical pendulum movements and is not a defect. Through careful adjustment of the regulating screw, it can be reduced to less than half a minute per day. If you expect higher accuracy, you are better served with a radio-controlled pendulum movement: the DCF77 signal is accurate to the second.

How do I maintain a mechanical pendulum movement in the long term?

A mechanical pendulum movement should be cleaned and re-lubricated by a professional every 5 to 10 years. Dried-out oil in the escapement area is the most common cause for a movement suddenly stopping or running irregularly. In everyday life, it is recommended to protect the clock from direct sunlight and strong temperature fluctuations, as both change the viscosity of the lubricants.

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Setting Pendulum and Radio-Controlled Clocks: Step-by-Step

How a pendulum movement works and why accuracy depends on the pendulum